WO2016047746A1

WO2016047746A1 - Coating liquid, method for manufacturing led device using same, and led device

Info

Publication number: WO2016047746A1
Application number: PCT/JP2015/077077
Authority: WO
Inventors: 中林　亮
Original assignee: コニカミノルタ株式会社
Priority date: 2014-09-26
Filing date: 2015-09-25
Publication date: 2016-03-31

Abstract

The present invention addresses the problem of providing a coating liquid which is able to be applied to a desired region of an LED device with high accuracy, while being less susceptible to deterioration due to light or heat, and which is capable of efficiently forming a cured film for a long period of time, said cured film being able to reflect light. In order to solve the above-described problem, a coating liquid containing a white pigment, an alkoxysilane compound and an organic solvent is configured such that if R2 (mol%) is the ratio of a bifunctional alkoxysilane compound relative to the total amount of the alkoxysilane compound, R3 (mol%) is the ratio of a trifunctional alkoxysilane compound relative to the total amount of the alkoxysilane compound and R4 (mol%) is the ratio of a tetrafunctional alkoxysilane compound relative to the total amount of the alkoxysilane compound (with the total of R2, R3 and R4 being 100 mol%), R2, R3 and R4 satisfy a specific condition. This coating liquid is also configured such that the organic solvent contains a high-surface-tension organic solvent having a surface tension at 25°C of 30 mN/m or more in an amount of 45-90% by mass relative to the total amount of the organic solvent.

Description

Coating liquid, LED device manufacturing method using the same, and LED device

The present invention relates to a coating solution, a method for manufacturing an LED device using the same, and an LED device.

In recent years, phosphors such as YAG phosphors have been placed in the vicinity of gallium nitride (GaN) -based blue LED (Light Emitting Diode) chips to receive blue light and blue light emitted from the blue LED elements. An LED device that obtains white light by mixing yellow light emitted from a phosphor has been developed. There is also an LED device that obtains white light by arranging various phosphors in the vicinity of a blue LED element and mixing blue light emitted from the blue LED element with red light and green light emitted from the phosphor upon receiving blue light. Has been developed.

White LED devices have a variety of uses, for example, there is a demand as an alternative to fluorescent lamps and incandescent lamps. Such an illuminating device has a structure in which a plurality of white LED devices are combined. And how to raise the light extraction efficiency of each white LED device is important in realizing cost reduction and long life of the lighting device.

On the other hand, the conventional LED device has a problem that the substrate on which the LED element is arranged easily absorbs the emitted light of the LED element and the fluorescence emitted by the phosphor, and the light extraction property is difficult to increase. Therefore, it has been proposed to arrange a reflector having a high light reflectance around the LED element. Such a reflector is generally formed of metal plating or the like. However, a reflector made of metal plating cannot be formed on the entire surface of the substrate from the viewpoint of preventing electrical conduction. Therefore, there is a problem that light is absorbed by the substrate in the region where the reflector is not formed.

Therefore, a reflector in which the metal plating is protected with a transparent resin layer (Patent Document 1) and a reflector in which the metal plating is covered with a white resin layer have been proposed (Patent Document 2). A dispersed reflector (reflective layer) has also been proposed (Patent Document 3).

JP 2005-136379 A JP 2011-23621 A International Publication No. 2014/017108

When the reflector surface made of metal plating is covered with a transparent resin as in the technique of Patent Document 1 described above, the resin deteriorates due to heat or light. And there was a problem that metal plating corrodes with time and the light reflectivity is lowered or electricity is conducted. In particular, in applications where a large amount of light is required, such as in-vehicle headlights, the resin is likely to deteriorate.

Also, when a reflector made of metal plating is coated with a relatively high heat resistant silicone resin, the silicone resin is unlikely to deteriorate. On the other hand, the silicone resin has a property that gas easily permeates. Therefore, when the reflector contains silver or is made of silver plating or the like, silver is discolored due to a small amount of hydrogen sulfide existing in the air, so that the reflectance is easily lowered, and the light extraction efficiency is easily lowered.

In addition, as in the technique of Patent Document 2, when a reflective layer is formed by coating a substrate or metal plating with a thermosetting resin in which a white pigment is dispersed, thermosetting such as epoxy having an organic substance as a main skeleton. The resin was easily colored at a high temperature, and the reflectance of the reflective layer was likely to decrease.

On the other hand, a ceramic binder having high heat resistance is used for forming the reflective layer described in Patent Document 3. However, the coating liquid for forming a reflective layer described in Patent Document 3 tends to wet and spread on the substrate during coating. And when it was going to form a reflection layer in the vicinity of a LED element, the coating liquid might adhere to the side surface of a LED element. When the coating liquid adheres to the side surface of the LED element, there is a problem that light cannot be extracted from the LED element side surface, and the light extraction efficiency from the LED element decreases.

The present invention has been made in view of such a situation. That is, the present invention provides a coating liquid that can be applied to a desired region of an LED device with high accuracy, can be formed with a cured film that is less susceptible to light and heat, and can efficiently reflect light over a long period of time. The purpose is to provide.

The first of the present invention relates to the coating solution shown below.
[1] A coating liquid containing a white pigment, an alkoxysilane compound, and an organic solvent, wherein the ratio of the bifunctional alkoxysilane compound to the total amount of the alkoxysilane compound is R2 (mol%), the trifunctional alkoxysilane compound When the ratio is R3 (mol%) and the ratio of the tetrafunctional alkoxysilane compound is R4 (mol%) (however, the total of R2, R3, and R4 is 100 mol%), both of the following

formulas

1 and 2 Meet the requirements,
0 ≦ R2 <40 (Formula 1)
0 ≦ R4 / R3 ≦ 3 (Formula 2)
The coating solution, wherein the organic solvent contains 45 to 90% by mass of a high surface tension organic solvent having a surface tension of 30 mN / m or more at 25 ° C. with respect to the total amount of the organic solvent.

[2] The high surface tension organic solvent is selected from the group consisting of monohydric alcohols, polyhydric alcohols, ketone solvents, ester solvents, amine solvents, amide solvents, and sulfur-containing solvents. The coating liquid as described.
[3] The coating liquid according to [1] or [2], wherein at least a part of the alkoxysilane compound is a polymer of a bifunctional alkoxysilane compound, a trifunctional alkoxysilane compound, or a tetrafunctional alkoxysilane compound.
[4] The coating solution according to any one of [1] to [3], further comprising inorganic particles or clay mineral particles.

[5] The coating solution according to any one of [1] to [4], further containing a silane coupling agent.
[6] The coating solution according to any one of [1] to [5], wherein the viscosity measured at 25 ° C. with a vibration viscometer is more than 5 mPa · s and not more than 2000 mPa · s.
[7] The coating solution according to any one of [1] to [6], containing a white pigment in an amount of 50 to 95% by mass with respect to the total mass of the solid content after heat curing.

2nd of this invention is related with the manufacturing method of an LED device shown below, and an LED device.
[8] A method for manufacturing an LED device, comprising: a substrate; an LED element disposed on the substrate; and a reflective layer formed around the LED element, wherein the LED element is disposed on the substrate. A method for manufacturing an LED device, comprising a step of applying and curing the coating liquid according to any one of [1] to [7] around the periphery.
[9] The method for manufacturing an LED device according to [8], wherein the coating liquid is applied by a non-contact type discharge device.
[10] The method for manufacturing an LED device according to [9], wherein the discharge device is a jet dispenser.

[11] An LED device comprising a substrate, an LED element disposed on the substrate, and a reflective layer formed on the substrate around the LED element, wherein the reflective layer is [1] An LED device, which is a cured film of the coating liquid according to any one of [7] to [7].
[12] The LED device according to [11], wherein the reflective layer is further formed between the substrate and the LED element.

The coating liquid of the present invention can be accurately applied to a desired region of the LED device. In addition, the reflective layer obtained by curing the coating solution is less deteriorated by heat and light, and can efficiently reflect light over a long period of time.

It is a schematic sectional drawing which shows an example of the LED apparatus of this invention. It is a top view which shows an example of the LED device of this invention. 2 is a graph showing an example of a solid-state Si-NMR spectrum.

Hereinafter, the present invention will be described in detail, but the present invention is not limited to the following embodiments, and various modifications can be made within the scope of the gist.

1. Coating liquid The coating liquid of the present invention is a composition for forming a reflective layer of an LED device, and the coating liquid contains a white pigment, an alkoxysilane compound, and an organic solvent. In addition to the white pigment, the coating liquid may contain inorganic particles, clay mineral particles, a silane coupling agent, and the like.

An example of an LED device having a reflective layer obtained by applying the coating liquid of the present invention is shown in FIG. As shown in the schematic cross-sectional view of FIG. 1, the LED device 100 has a structure in which an LED element 2 is electrically connected to a substrate 1. Furthermore, the wavelength conversion layer 11 which converts the light of the specific wavelength which LED element 2 radiate | emits into the light of another specific wavelength may be arrange | positioned so that the said LED element 2 may be covered. And in order to take out efficiently the light which LED element 2 emits, and the light which the fluorescent substance contained in wavelength conversion layer 11 emits from light extraction surface 10A of LED device 100, substrate 1 other than the field where LED element 2 is arranged A reflective layer 21 for reflecting these lights is formed on the surface.

Here, a resin is often used for the binder of the reflection layer of the conventional LED device. However, the resin may be colored or deteriorated by heat or light, and there has been a problem that the light extraction efficiency tends to decrease. Therefore, it has also been proposed to form a reflective layer by applying a coating liquid in which a polysiloxane precursor and a white pigment are mixed. However, the conventional coating liquid containing a polysiloxane precursor and a white pigment has a problem that it easily spreads on the substrate surface and it is difficult to form a reflective layer only in a desired region. In particular, when the coating solution is too wet and spreads, it adheres to the side surface of the LED element, making it difficult to extract light from the side surface of the LED element. As a result, the light extraction efficiency of the LED device may decrease.

In contrast, the coating solution of the present invention contains a certain amount of a high surface tension organic solvent having a surface tension of 30 mN / m or more at 25 ° C., so that the coating solution does not spread excessively. That is, the coating liquid can be applied only to a desired region, and for example, the reflective layer can be formed near the outer periphery of the LED element without covering the side surface of the LED element. As a result, the light extraction efficiency from the LED device is increased. Further, since the binder of the reflective layer obtained from the coating solution is polysiloxane, the reflective layer is hardly deteriorated by light or heat. Therefore, in an LED device having a reflective layer made of a cured film of the coating solution, high light extraction efficiency is maintained over a long period.

1-1. Alkoxysilane Compound The coating liquid of the present invention contains an alkoxysilane compound. The alkoxysilane compound is a compound that is hydrolyzed and polycondensed into a polysiloxane when the coating solution is cured. And polysiloxane becomes a binder of the above-mentioned reflective layer.

The alkoxysilane compound includes at least one of a bifunctional alkoxysilane compound, a trifunctional alkoxysilane compound, and a tetrafunctional alkoxysilane compound. The ratio of the bifunctional alkoxysilane compound to the total amount of the alkoxysilane compound is R2 (mol%), the ratio of the trifunctional alkoxysilane compound is R3 (mol%), and the ratio of the tetrafunctional alkoxysilane compound is R4 (mol%). , Both conditions of the following formula 1 and formula 2 are satisfied.
0 ≦ R2 <40 (Formula 1)
0 ≦ R4 / R3 ≦ 3 (Formula 2)
In addition, the sum total of R2, R3, and R4 is 100 mol%.

In Formula 1, when R2 is 40 or more, the polysiloxane contains a relatively large amount of organic groups derived from bifunctional alkoxysilane. As a result, it is difficult to form a sufficient siloxane bond between the reflective layer obtained by curing the coating solution and the OH group or the like on the substrate surface, and the adhesion between the reflective layer and the substrate is lowered. In addition, the gas barrier property of the reflective layer may be reduced, and the resistance to sulfurization may be reduced. Therefore, R2 is preferably in the above range, more preferably 0 ≦ R2 <30, and further preferably 0 ≦ R2 <25.

On the other hand, if the value of R4 / R3 exceeds 3 in Formula 2, that is, if the amount of the tetrafunctional alkoxysilane compound is excessive, the crosslink density in the polysiloxane is excessively increased. Therefore, distortion is likely to occur when the alkoxysilane compound is cured, and cracks may occur. Therefore, the value of R4 / R3 is preferably 3 or less, more preferably 0 ≦ R4 / R3 <2, and further preferably 0 ≦ R4 / R3 <1.

The ratio of the bifunctional alkoxysilane compound, the trifunctional alkoxysilane compound, and the tetrafunctional alkoxysilane compound with respect to the total amount of the alkoxysilane compound in the coating solution is determined by the solid Si of the sample obtained by drying and solidifying the coating solution at 150 ° C. Each can be determined from the NMR spectrum.

The spectrum of solid-state Si-NMR (Nuclear Magnetic Resonance) will be described.
The tetrafunctional alkoxysilane compound polymer (polysiloxane) is represented by the SiO ₂ · nH ₂ O characteristic formula, but structurally, oxygen atoms O are bonded to the apexes of the silicon atom Si tetrahedron. These silicon atoms have a structure in which silicon atoms Si are further bonded to these oxygen atoms O and spread in a net shape.

The schematic diagrams (A) and (B) below show the Si—O net structure, ignoring the tetrahedral structure. The schematic diagram (A) shows a case where all of the oxygen atoms O are bonded to other Si atoms in the Si—O net structure. On the other hand, the schematic diagram (B) shows a case where part of the oxygen atom O is replaced with another member (here, —H) in the Si—O net structure. As shown in the schematic diagram (A), the Si atoms derived from the tetrafunctional alkoxysilane compound include four atoms (Q ⁴ ) bonded to —OSi, and three Si atoms as shown in the schematic diagram (B). Atom (Q ³ ) or the like bonded to —OSi. In the solid-state Si-NMR spectrum, these are observed as different peaks. Then, a peak based on the silicon atoms derived from the tetrafunctional alkoxysilane compound, are collectively referred to as Q sites, the peak derived from each atom, Q ⁴ peak, Q ³ peak, called .... In this specification, Q ⁰ to Q ⁴ peaks derived from the Q site are referred to as a Q ⁿ peak group. The Q ⁿ peak group of the silica film containing no organic substituent is usually observed as a multimodal peak continuous in the region of −80 to −130 ppm chemical shift.

On the other hand, a silicon atom (that is, silicon derived from a trifunctional alkoxysilane compound) in which three oxygen atoms are bonded and one non-oxygen atom (usually carbon) is bonded is generally referred to as a T site. Is done. The peak derived from the T site is observed as each peak of T ⁰ to T ³ as in the case of the Q site. In this specification, each peak derived from the T site is referred to as a ^Tn peak group. The T ⁿ peak group is generally observed as a multimodal peak continuous in a region on the higher magnetic field side (usually chemical shift of −80 to −40 ppm) than the Q ⁿ peak group.

Furthermore, a silicon atom (that is, silicon derived from a bifunctional alkoxysilane compound) in which two oxygen atoms are bonded and two atoms other than oxygen (usually carbon) are bonded is generally referred to as a D site. Is done. Similarly to the peak group derived from the Q site and the T site, the peak derived from the D site is also observed as each peak of D ⁰ to D ⁿ (D ⁿ peak group), which is further than the peak group of Q ⁿ and T ^n. It is observed as a multimodal peak in the region on the high magnetic field side (usually the region with a chemical shift of −3 to −40 ppm).

Here, when a solid Si-NMR measurement is performed, a spectrum as shown in FIG. 3 is obtained. However, FIG. 3 is an example of the spectrum of solid-state Si-NMR, and the spectrum of the cured product of the alkoxysilane compound contained in the coating solution of the present invention is not limited to this. In FIG. 3, the horizontal axis indicates the chemical shift, and the vertical axis indicates “relative strength” depending on the abundance of the compound having each structure.

In FIG. 3, D11 indicates actual measurement data. D12 indicates data modeled by a Gaussian function. D13 shows a difference spectrum. The peak P11 represents the ^{D n} peak group, the peak top of the ^{D n} peak group is present in the vicinity of chemical shift -20.0Ppm. The peak P12 represents the ^{T n} peak group, the peak top of the ^{T n} peak group is present in the vicinity of chemical shift -60.0Ppm. Further, the peak P13 represents a ^{Q n} peak group, the peak top of the ^{Q n} peak group is present in the vicinity of a chemical shift -100.0 ~ -110 ppm. That is, the spectrum of FIG. 3 shows that silicon derived from a bifunctional alkoxysilane compound, silicon derived from a trifunctional alkoxysilane compound, and silicon derived from a tetrafunctional alkoxysilane compound are included.

The area ratio of the respective peak groups of D ⁿ , T ⁿ , and Q ⁿ is equal to the molar ratio of silicon atoms placed in the environment corresponding to each peak group. Therefore, Q ⁿ peak group, T ⁿ peak group, and to the total area of the D ⁿ peak group, the ratio of the area of each peak group, the total amount of the alkoxysilane compound contained in the coating liquid (the total molar amount of silicon atoms) And the molar ratio of each alkoxysilane compound (tetrafunctional alkoxysilane compound, trifunctional alkoxysilane compound, and bifunctional alkoxysilane compound).

Here, the alkoxysilane compound may be in a monomer state; however, at least a part is preferably a polymer (oligomer) of bifunctional alkoxysilane, trifunctional alkoxysilane, or tetrafunctional alkoxysilane. If the alkoxysilane compound is an oligomer in which several to several tens of monomers are polymerized in advance, shrinkage when the coating solution is cured is reduced, and cracks are less likely to occur when the reflective layer is formed.

-Tetrafunctional alkoxysilane compound Examples of the tetrafunctional alkoxysilane compound include compounds represented by the following general formula (IV).
Si (OR ¹ ) ₄ (IV)
In the general formula (IV), each R ¹ independently represents an alkyl group or a phenyl group, preferably an alkyl group having 1 to 5 carbon atoms, or a phenyl group.

Specific examples of tetrafunctional alkoxysilane compounds include tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane, tetrabutoxysilane, tetrapentyloxysilane, tetraphenyloxysilane, trimethoxymonoethoxysilane, dimethoxydiethoxysilane, and triethoxymono. Methoxysilane, trimethoxymonopropoxysilane, monomethoxytributoxysilane, monomethoxytripentyloxysilane, monomethoxytriphenyloxysilane, dimethoxydipropoxysilane, tripropoxymonomethoxysilane, trimethoxymonobutoxysilane, dimethoxydibutoxysilane , Triethoxymonopropoxysilane, diethoxydipropoxysilane, tributoxymonopropoxysilane, dimethoxymonoethoxy Nobutoxysilane, diethoxymonomethoxymonobutoxysilane, diethoxymonopropoxymonobutoxysilane, dipropoxymonomethoxymonoethoxysilane, dipropoxymonomethoxymonobutoxysilane, dipropoxymonoethoxymonobutoxysilane, dibutoxymonomethoxymonoethoxy Examples thereof include alkoxysilanes such as silane, dibutoxymonoethoxymonopropoxysilane, monomethoxymonoethoxymonopropoxymonobutoxysilane, and aryloxysilane. Among these, tetramethoxysilane and tetraethoxysilane are preferable.

Trifunctional alkoxysilane compound Examples of the trifunctional alkoxysilane compound include compounds represented by the following general formula (III).
R ² Si (OR ³ ) ₃ (III)
In the general formula (III), each R ³ independently represents an alkyl group or a phenyl group, preferably an alkyl group having 1 to 5 carbon atoms, or a phenyl group. R ² represents a hydrogen atom or an alkyl group.

Specific examples of the trifunctional alkoxysilane compound include trimethoxysilane, triethoxysilane, tripropoxysilane, tripentyloxysilane, triphenyloxysilane, dimethoxymonoethoxysilane, diethoxymonomethoxysilane, dipropoxymonomethoxysilane, Dipropoxymonoethoxysilane, dipentyloxylmonomethoxysilane, dipentyloxymonoethoxysilane, dipentyloxymonopropoxysilane, diphenyloxylmonomethoxysilane, diphenyloxymonoethoxysilane, diphenyloxymonopropoxysilane, methoxyethoxypropoxysilane, monopropoxydimethoxy Silane, monopropoxydiethoxysilane, monobutoxydimethoxysilane, monopentyloxydiethoxysila Monohydrosilane compounds such as monophenyloxydiethoxysilane; methyltrimethoxysilane, methyltriethoxysilane, methyltripropoxysilane, methyltripentyloxysilane, methylmonomethoxydiethoxysilane, methylmonomethoxydipropoxysilane, methylmono Monomethylsilane compounds such as methoxydipentyloxysilane, methylmonomethoxydiphenyloxysilane, methylmethoxyethoxypropoxysilane, methylmonomethoxymonoethoxymonobutoxysilane; ethyltrimethoxysilane, ethyltripropoxysilane, ethyltripentyloxysilane, ethyltri Phenyloxysilane, ethylmonomethoxydiethoxysilane, ethylmonomethoxydipropoxysilane, ethylmonomethoxydipe Monoethylsilane compounds such as tiloxysilane, ethylmonomethoxydiphenyloxysilane, ethylmonomethoxymonoethoxymonobutoxysilane; propyltrimethoxysilane, propyltriethoxysilane, propyltripentyloxysilane, propyltriphenyloxysilane, propylmono Monopropylsilane compounds such as methoxydiethoxysilane, propylmonomethoxydipropoxysilane, propylmonomethoxydipentyloxysilane, propylmonomethoxydiphenyloxysilane, propylmethoxyethoxypropoxysilane, propylmonomethoxymonoethoxymonobutoxysilane; butyltrimethoxy Silane, butyltriethoxysilane, butyltripropoxysilane, butyltripentyloxysilane, butyl Mono, such as triphenyloxysilane, butylmonomethoxydiethoxysilane, butylmonomethoxydipropoxysilane, butylmonomethoxydipentyloxysilane, butylmonomethoxydiphenyloxysilane, butylmethoxyethoxypropoxysilane, butylmonomethoxymonoethoxymonobutoxysilane A butylsilane compound is included.

When R ² represented by the general formula (III) of these trifunctional alkoxysilane compounds is a methyl group, the hydrophobicity of the resulting reflective layer surface becomes low. Thereby, when forming a wavelength conversion layer on a reflective layer, the composition for forming a wavelength conversion layer becomes easy to spread. As a result, the adhesion between the reflective layer and the wavelength conversion layer is enhanced. Examples of the trifunctional alkoxysilane compound in which R ² represented by the general formula (III) is a methyl group include methyltrimethoxysilane and methyltriethoxysilane, and is particularly preferably methyltrimethoxysilane. .

-Bifunctional alkoxysilane compound Examples of the bifunctional alkoxysilane compound include compounds represented by the following general formula (II).
R ⁴ ₂ Si (OR ⁵ ) ₂ (II)
In the general formula (II), each R ⁵ independently represents an alkyl group or a phenyl group, preferably an alkyl group having 1 to 5 carbon atoms, or a phenyl group. R ⁴ represents a hydrogen atom or an alkyl group.

Specific examples of the bifunctional alkoxysilane compound include dimethoxysilane, diethoxysilane, dipropoxysilane, dipentyloxysilane, diphenyloxysilane, methoxyethoxysilane, methoxypropoxysilane, methoxypentyloxysilane, methoxyphenyloxysilane, ethoxy Propoxysilane, ethoxypentyloxysilane, ethoxyphenyloxysilane, methyldimethoxysilane, methylmethoxyethoxysilane, methyldiethoxysilane, methylmethoxypropoxysilane, methylmethoxypentyloxysilane, methylmethoxyphenyloxysilane, ethyldipropoxysilane, ethyl Methoxypropoxysilane, ethyldipentyloxysilane, ethyldiphenyloxysilane, propyldimethoxysilane , Propylmethoxyethoxysilane, propylethoxypropoxysilane, propyldiethoxysilane, propyldipentyloxysilane, propyldiphenyloxysilane, butyldimethoxysilane, butylmethoxyethoxysilane, butyldiethoxysilane, butylethoxypropoxysilane, butyldipropoxy Silane, butylmethyldipentyloxysilane, butylmethyldiphenyloxysilane, dimethyldimethoxysilane, dimethylmethoxyethoxysilane, dimethyldiethoxysilane, dimethyldipentyloxysilane, dimethyldiphenyloxysilane, dimethylethoxypropoxysilane, dimethyldipropoxysilane, diethyldimethoxy Silane, diethylmethoxypropoxysilane, diethyldiethoxysilane Diethylethoxypropoxysilane, dipropyldimethoxysilane, dipropyldiethoxysilane, dipropyldipentyloxysilane, dipropyldiphenyloxysilane, dibutyldimethoxysilane, dibutyldiethoxysilane, dibutyldipropoxysilane, dibutylmethoxypentyloxysilane, dibutylmethoxy Phenyloxysilane, methylethyldimethoxysilane, methylethyldiethoxysilane, methylethyldipropoxysilane, methylethyldipentyloxysilane, methylethyldiphenyloxysilane, methylpropyldimethoxysilane, methylpropyldiethoxysilane, methylbutyldimethoxysilane, methyl Butyldiethoxysilane, methylbutyldipropoxysilane, methylethylethoxypropoxy Run, ethylpropyldimethoxysilane, ethylpropylmethoxyethoxysilane, dipropyldimethoxysilane, dipropylmethoxyethoxysilane, propylbutyldimethoxysilane, propylbutyldiethoxysilane, dibutylmethoxyethoxysilane, dibutylmethoxypropoxysilane, dibutylethoxypropoxysilane, etc. Is included. Of these, dimethoxysilane, diethoxysilane, methyldimethoxysilane, and methyldiethoxysilane are preferable.

-Oligomer An oligomer that can be an alkoxysilane compound is obtained by mixing a bifunctional alkoxysilane compound, a trifunctional alkoxysilane compound, and a tetrafunctional alkoxysilane compound in a desired ratio and reacting them in the presence of a catalyst, water, and a solvent. It is done. The molecular weight of the oligomer is adjusted by the reaction time, temperature, catalyst, water concentration, and the like.

The oligomer preferably has a weight average molecular weight of 500 to 20000 as measured by GPC (gel permeation chromatograph), more preferably 1000 to 10,000, and even more preferably 1500 to 6000. If the degree of polymerization of the oligomer is too high, the viscosity of the coating solution may become excessively high, or the alkoxysilane compound may precipitate in the coating solution.

Examples of the catalyst for preparing the oligomer include acids, metal alkoxides, metal chelates and the like. Specific examples of the acid include carboxylic acids such as hydrochloric acid, nitric acid, phosphoric acid, and acetic acid.

The metal alkoxide or metal chelate is preferably a metal alkoxide or metal chelate containing a group 4 or group 13 metal element other than Si, and a compound represented by the following general formula (V) is preferable.
M ^{m +} X _n Y _mn (V)
In the general formula (V), M represents a group 4 or group 13 metal element (excluding Si), and m represents the valence of M (3 or 4). X represents a hydrolyzable group, and n represents the number of X groups (an integer of 2 or more and 4 or less). However, m ≧ n. Y represents a monovalent organic group.

In the general formula (V), the group 4 or group 13 metal element represented by M is preferably aluminum, zirconium, or titanium, and particularly preferably zirconium.

In the general formula (V), the hydrolyzable group represented by X may be a group that is hydrolyzed with water to form a hydroxyl group. Preferable examples of the hydrolyzable group include a lower alkoxy group having 1 to 5 carbon atoms, an acetoxy group, a butanoxime group, a chloro group and the like. In general formula (V), all the groups represented by X may be the same group or different groups.

The hydrolyzable group represented by X is hydrolyzed and released. Therefore, the compound produced after hydrolysis from the group represented by X is preferably neutral and light boiling. Therefore, the group represented by X is preferably a lower alkoxy group having 1 to 5 carbon atoms, more preferably a methoxy group or an ethoxy group.

In the general formula (V), the monovalent organic group represented by Y may be a monovalent organic group contained in a general silane coupling agent. Specifically, the aliphatic group, alicyclic group, aromatic group, fatty acid having 1 to 1000 carbon atoms, preferably 500 or less, more preferably 100 or less, further preferably 40 or less, and particularly preferably 6 or less. It may be a ring aromatic group. The organic group represented by Y may be an aliphatic group, an alicyclic group, an aromatic group, or a group in which an alicyclic aromatic group is bonded via a linking group. The linking group may be an atom such as O, N, or S, or an atomic group containing these.

The organic group represented by Y may have a substituent. Examples of the substituent include halogen atoms such as F, Cl, Br, and I; vinyl group, methacryloxy group, acryloxy group, styryl group, mercapto group, epoxy group, epoxycyclohexyl group, glycidoxy group, amino group, cyano group, Organic groups such as nitro group, sulfonic acid group, carboxy group, hydroxy group, acyl group, alkoxy group, imino group and phenyl group are included.

Specific examples of the metal alkoxide or metal chelate represented by the general formula (V) include aluminum triisopropoxide, aluminum tri-n-butoxide, aluminum tri-t-butoxide, aluminum triethoxide and the like.

Specific examples of the metal alkoxide or metal chelate of zirconium represented by the general formula (V) include zirconium tetramethoxide, zirconium tetraethoxide, zirconium tetra n-propoxide, zirconium tetra i-propoxide, zirconium tetra n- Examples include butoxide, zirconium tetra-i-butoxide, zirconium tetra-t-butoxide, zirconium dimethacrylate dibutoxide, zirconium tetraacetylacetonate, dibutoxyzirconium bis (ethylacetoacetate) and the like.

Specific examples of the metal alkoxide or metal chelate of the titanium element represented by the general formula (V) include titanium tetraisopropoxide, titanium tetra n-butoxide, titanium tetra i-butoxide, titanium methacrylate triisopropoxide, titanium tetra Includes methoxypropoxide, titanium tetra n-propoxide, titanium tetraethoxide, titanium lactate, titanium bis (ethylhexoxy) bis (2-ethyl-3-hydroxyhexoxide), titanium acetylacetonate, titanium ethylacetoacetate, etc. It is.

However, the metal alkoxides or metal chelates exemplified above are a part of commercially available organometallic alkoxides or metal chelates. Metal alkoxides or metal chelates shown in the list of coupling agents and related products in Chapter 9 “Optimum Utilization Technology of Coupling Agents” published by the National Institute of Science and Technology are also applicable to the present invention.

Examples of solvents for preparing oligomers include monohydric alcohols such as methanol, ethanol, propanol and n-butanol; alkyl carboxylic acid esters such as methyl-3-methoxypropionate and ethyl-3-ethoxypropionate; ethylene Polyhydric alcohols such as glycol, diethylene glycol, propylene glycol, glycerin, trimethylolpropane, hexanetriol; ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monopropyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl Ether, diethylene glycol monopropyl ether, diethylene glycol monobutyl ether, pro Monoethers of polyhydric alcohols such as lenglycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monopropyl ether, propylene glycol monobutyl ether, or their monoacetates; esters such as methyl acetate, ethyl acetate, butyl acetate Ketones such as acetone, methyl ethyl ketone, methyl isoamyl ketone; ethylene glycol dimethyl ether, ethylene glycol diethyl ether, ethylene glycol dipropyl ether, ethylene glycol dibutyl ether, propylene glycol dimethyl ether, propylene glycol diethyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol Methyl Polyhydric alcohols ethers and polyvalent all alkyl etherifying hydroxyl groups of alcohols such Chirueteru; and the like. These may be added alone or in combination of two or more.

-Content of alkoxysilane compound The total amount of alkoxysilane compound contained in the coating solution is 5 to 40% by mass relative to the total mass of components other than the solvent (organic solvent and water) contained in the coating solution. Preferably, it is 10 to 30% by mass. When the total amount of the alkoxysilane compound is less than 5% by mass, the white pigment is not sufficiently bound in the resulting reflective layer. As a result, pigment powder is easily generated on the surface of the reflective layer. On the other hand, when the total amount of the alkoxysilane compound exceeds 40% by mass, the amount of the white pigment is relatively reduced, and the light reflectivity of the reflective layer tends to be low.

1-2. Organic Solvent The organic solvent contained in the coating solution is an organic solvent that is compatible with the aforementioned alkoxysilane compound and can uniformly disperse the white pigment and the like. Here, the organic solvent contains 45 to 90% by mass of a high surface tension organic solvent having a surface tension of 30 mN / m or more at 25 ° C. with respect to the total amount of the organic solvent. The surface tension is a value measured by the Wilhelmy method (plate method). When the organic solvent having a surface tension of 30 mN / m or more is contained in an amount of 40% by mass or more, it is difficult for the coating liquid of the present invention to spread when the coating liquid adheres to the substrate. That is, it becomes possible to apply the coating liquid only to a desired region. However, many high surface tension organic solvents have a high boiling point, and if the concentration of the high surface tension organic solvent is too high, the organic solvent will not easily evaporate during the formation of the reflective layer, or there will be no solvent in the reflective layer. It tends to remain. Therefore, when the concentration is 90% by mass or less, the organic solvent can be efficiently volatilized. The amount of the high surface tension organic solvent is more preferably 50 to 80% by mass, and further preferably 60 to 80% by mass.

Examples of the high surface tension organic solvent include monohydric alcohol, polyhydric alcohol, ketone solvent, ester solvent, amine solvent, amide solvent, sulfur-containing solvent and the like.

Examples of monohydric alcohols having a surface tension of 30 mN / m or more include ethylene glycol monomethyl ether, benzyl alcohol, diacetone alcohol, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, triethylene glycol monobutyl ether, tetraethylene glycol monobutyl ether, Tripropylene glycol monomethyl ether, 2-phenoxyethanol and the like are included.

Examples of polyhydric alcohols having a surface tension of 30 mN / m or more include diethylene glycol, dipropylene glycol, 1,2-butanediol, 1,4-butanediol, 2,3-butanediol, 1,5-pentanediol , Glycols and the like.

Examples of ketone solvents include cyclohexanone and the like, and examples of ester solvents include ethylene glycol diacetate, diethylene glycol monoethyl ether acetate, γ-butyrolactone, ethyl acetoacetate and the like. Examples of amine solvents include monoethanolamine; examples of amide solvents include 2-pyrrolidone, N-methylpyrrolidone, ε-caprolactam, etc .; examples of sulfur-containing solvents include dimethyl Examples include sulfoxide, tetrahydrothiophene-1,1-dioxide and the like.

Among these, monohydric alcohols or dihydric alcohols are preferable from the viewpoints of handleability and availability, and ethylene glycol monomethyl ether (surface tension: 31.8), benzyl alcohol (surface tension: 39), diacetone alcohol (surface tension: 31), ethylene glycol (surface tension: 48.4), propylene glycol (surface tension: 35.3), 1,3-butanediol (surface tension: 45.3), Triethylene glycol (surface tension: 45.2).

On the other hand, the solvent (low surface tension solvent) having a surface tension of less than 30 mN / m contained in the organic solvent is not particularly limited, and may be a monohydric alcohol, an ether solvent, a ketone solvent, an ester solvent, or the like. Specifically, methanol, ethanol, 2-propanol (isopropanol), n-butanol, 1-propanol, 2-butanol, pentanol, hexanol, heptanol, octanol, ethylene glycol monoethyl ether, ethylene glycol monopropyl ether, ethylene Monohydric alcohols such as glycol monobutyl ether, diethylene glycol monobutyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monobutyl ether; ether solvents such as diethylene glycol dimethyl ether and diethylene glycol diethyl ether; ketone solvents such as acetone and methyl ethyl ketone; Methyl-3-methoxypropionate, methyl acetate, acetic acid Chill, propyl acetate, it may be ester solvents such as butyl acetate.

The total amount of the organic solvent contained in the coating solution is preferably 20 to 90% by mass, more preferably 30 to 70% by mass with respect to the total amount of the coating solution. When the total amount of the organic solvent is too small, the viscosity of the coating solution increases and the coating stability decreases. On the other hand, when the total amount of the organic solvent is excessive, the viscosity of the coating solution is lowered, and the white pigment may settle in the coating solution.

1-3. White pigment The white pigment contained in the coating liquid plays a role of reflecting light emitted from the LED element in the reflective layer. In the present invention, the white pigment is a particle having an average primary particle size of more than 100 nm and 20 μm or less, and a refractive index of light of d-line (wavelength: 587.96 nm) of 1.6 or more. The average primary particle size of the white pigment is preferably larger than 100 nm and not larger than 10 μm, more preferably 200 nm to 2.5 μm. The “average primary particle size” refers to the value of D50 measured with a laser diffraction particle size distribution meter. Examples of the laser diffraction particle size distribution measuring device include a laser diffraction particle size distribution measuring device manufactured by Shimadzu Corporation.

Examples of white pigments include barium carbonate, barium sulfate, zinc oxide, magnesium oxide, calcium oxide, titanium oxide, aluminum oxide, zirconium oxide, zinc sulfide, aluminum hydroxide, boron nitride, aluminum nitride, potassium titanate, titanate Barium, aluminum titanate, strontium titanate, calcium titanate, magnesium titanate, hydroxyapatite, and the like are included. The white pigment is particularly preferably titanium oxide, aluminum oxide, barium sulfate, zinc oxide, and boron nitride.

When boron nitride is contained in the white pigment, the resulting reflective layer has high thermal conductivity. As a result, the heat generated from the LED element can be quickly released from the substrate. Therefore, the temperature of the LED device can be kept low, and the device life can be extended.

The amount of the white pigment contained in the coating solution is preferably 50 to 95% by mass, more preferably 60 to 95% by mass, and still more preferably based on the mass of the solid content after heat curing of the coating solution. Is 70 to 90% by mass. When the amount of the white pigment is 50% by mass or more, the light reflectivity of the resulting reflective layer is likely to be sufficiently increased. On the other hand, when the content of the white pigment is 95% by mass or less, the amount of the binder is relatively increased and the white pigment is easily bound. The mass of the solid content after heat curing of the coating solution is the mass of a cured product obtained by curing the coating solution at 150 ° C. for 1 hour. On the other hand, the amount of the white pigment is specified by the blending amount at the time of preparing the coating liquid, and EDX and XRD analysis. EDX and XRD analyzes are performed as follows. Specifically, (1) component analysis of the film | membrane after baking a coating liquid at 150 degreeC for 1 hour is carried out by EDX, and the ratio according to element is computed from the contrast etc. of a SEM photograph. (2) The structure is analyzed by XRD analysis, and the type of white pigment is specified. Thereby, the kind of white pigment and its content are specified.

1-4. Inorganic particles The coating solution may further contain inorganic particles. The inorganic particles are particles made of an inorganic material other than the white pigment described above. The inorganic particles can be, for example, metal oxide fine particles having an average particle size of 5 nm or more and less than 100 nm. When the metal oxide fine particles are contained in the coating solution, fine irregularities are generated on the surface of the resulting reflective layer, and an anchor effect is easily exhibited between the reflective layer and other layers. Moreover, when metal oxide fine particles are contained in the coating solution, the stress generated in the film during the polycondensation of the alkoxysilane compound is relaxed, and cracks are less likely to occur in the resulting reflective layer.

The type of metal oxide fine particles is not particularly limited, but is relatively easy to obtain from the group of aluminum oxide, zirconium oxide, zinc oxide, tin oxide, yttrium oxide, cerium oxide, titanium oxide, copper oxide, and bismuth oxide. One or more selected metal oxide fine particles are preferable.

The surface of the metal oxide fine particles may be treated with a silane coupling agent or a titanium coupling agent. By the surface treatment, the compatibility between the metal oxide fine particles and the alkoxysilane compound or the organic solvent is increased.

The average particle diameter of the metal oxide fine particles is preferably 5 to 100 nm, more preferably 5 to 80 nm, still more preferably 5 to 50 nm in consideration of the respective effects described above. By setting the average particle diameter in such a range, fine irregularities can be formed on the surface of the reflective layer, and the anchor effect described above can be obtained. The average particle diameter of the metal oxide fine particles is measured, for example, by a Coulter counter method.

The metal oxide fine particles may be porous, and the specific surface area is preferably 200 m ² / g or more. If the metal oxide fine particles are porous, impurities are easily adsorbed in the porous voids.

The amount of the metal oxide fine particles contained in the coating solution is preferably 0.1 to 20% by mass with respect to the total mass of components other than the solvent (organic solvent and water) contained in the coating solution. More preferably, it is mass%. If the amount of the metal oxide fine particles is too small, the above-described anchor effect is not sufficient. On the other hand, if the amount is too large, the amount of the alkoxysilane compound is relatively reduced, and the strength of the resulting reflective layer may be reduced.

Meanwhile, the inorganic particles may include other inorganic particles having an average primary particle size of 100 nm or more and 100 μm or less. When such other inorganic particles are contained, the gaps between the white pigments are filled with the inorganic particles, and the viscosity of the coating liquid is increased.

Examples of other inorganic particles include oxide particles such as silicon oxide, fluoride particles such as magnesium fluoride, and mixtures thereof. The other inorganic particles are preferably oxide particles, and particularly preferably silicon oxide.
The surface of other inorganic particles may be treated with a silane coupling agent or a titanium coupling agent. By the surface treatment, compatibility between the other inorganic particles and the alkoxysilane compound or the organic solvent is increased.

The content of other inorganic particles contained in the coating solution is preferably 0.1 to 10% by mass, more preferably 0.2 to 5% by mass, based on the total mass of the coating solution. . This is because if the other inorganic particles exceed 10% by mass, cracks are likely to occur during the formation of the reflective layer, and if it is less than 0.1%, the thickening effect of the coating solution is reduced.

The average particle diameter of the other inorganic particles is preferably 100 nm or more and 50 μm or less, and more preferably 1 μm or more and 30 μm or less from the viewpoint of filling a gap generated at the interface between the white pigments. The average particle diameter of other inorganic particles can be measured by, for example, a Coulter counter method.

1-5. Clay mineral particles The coating liquid may contain clay mineral particles. When clay mineral particles are contained in the coating solution, the viscosity of the coating solution increases, and sedimentation of the white pigment is suppressed. Examples of clay mineral particles include layered silicate minerals, imogolite, allophane and the like. These particles have a very large surface area and can increase the viscosity of the coating solution in a small amount.

Here, the layered silicate mineral is preferably a clay mineral having a mica structure, a kaolinite structure, or a smectite structure. The layered silicate mineral particles tend to form a card house structure when the coating solution is left standing. When the layered silicate mineral particles form a card house structure, the viscosity of the coating solution is greatly increased. On the other hand, the card house structure is apt to collapse by applying a certain pressure, thereby reducing the viscosity of the coating solution. That is, when the layered silicate mineral particles are contained in the coating solution, the viscosity of the coating solution increases in a stationary state, and the viscosity of the coating solution decreases when a certain pressure is applied.

Examples of such layered silicate minerals include natural or synthetic hectrite, saponite, stevensite, hydelite, montmorillonite, nontrinite, bentonite, laponite and other smectite clay minerals, and Na-type tetralithic fluoric mica. Non-swelling mica such as swellable mica genus clay minerals such as Li-type tetralithic fluorine mica, Na-type fluorine teniolite, Li-type fluorine teniolite, muscovite, phlogopite, fluorine phlogopite, sericite, potassium tetrasilicon mica Genus clay minerals, vermiculite and kaolinite, or mixtures thereof.

Examples of commercial products of clay mineral particles include Laponite XLG (synthetic hectorite analogue manufactured by LaPorte, UK), Laponite RD (Synthetic hectorite analogue produced by LaPorte, UK), Thermabis (Synthetic product, Henkel, Germany) Hectorite-like substance), smecton SA-1 (saponite-like substance manufactured by Kunimine Industry Co., Ltd.), Bengel (natural bentonite sold by Hojun Co., Ltd.), Kunivia F (natural montmorillonite sold by Kunimine Industry Co., Ltd.), bee gum ( Natural hectorite manufactured by Vanderbilt, USA, Daimonite (synthetic swellable mica manufactured by Topy Industries, Ltd.), Micromica (synthetic non-swellable mica, manufactured by Coop Chemical Co., Ltd.), Somasifu (Coop Chemical Co., Ltd.) ) Synthetic swelling mica), SWN (Synthetic smectite manufactured by Coop Chemical Co., Ltd.), SWF Synthetic smectite manufactured by Co-op Chemical Co., Ltd., M-XF (white mica manufactured by Repco Co., Ltd.), S-XF (metal mica manufactured by Repco Co., Ltd.), PDM-800 (manufactured by Topy Industries, Ltd.) Fluorine phlogopite mica), sericite OC-100R (sericite produced by Oakem Tsusho Co., Ltd.), PDM-K (G) 325 (potassium tetrasilicon mica produced by Topy Industries, Ltd.), and the like.

The content of clay mineral particles is preferably from 0.1 to 5% by mass, more preferably from 0.2 to 2% by mass, based on the total mass of the coating solution. When the content of clay mineral particles is small, the viscosity of the coating solution is difficult to increase, and the white pigment tends to settle. On the other hand, if the content of the clay mineral particles is excessive, the viscosity of the coating solution becomes too high, and the coating solution may not be discharged uniformly from the coating device.

The surface of the clay mineral particles may be modified (surface treatment) with an ammonium salt or the like in consideration of compatibility with the solvent in the coating solution.

1-6. Silane coupling agent The coating solution may further contain a silane coupling agent. When the silane coupling agent is contained in the coating solution, the adhesion between the resulting reflective layer and the substrate is increased, and the durability of the LED device is improved.

Examples of silane coupling agents include vinyltrimethoxysilane, vinyltriethoxysilane, 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyl Methyldiethoxysilane, 3-glycidoxypropyltriethoxysilane, p-styryltrimethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropyltriethoxysilane, 3 -Acryloxypropyltrimethoxysilane, N-2- (aminoethyl) -3-aminopropylmethyldimethoxysilane, N-2- (aminoethyl) -3-aminopropyltrimethoxysilane, N-2- (aminoethyl) -3-A Nopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, 3-triethoxysilyl-N- (1,3-dimethyl-butylidene) propylamine, N-phenyl-3-aminopropyltriethoxysilane, N- (vinyl) Benzyl) -2-aminoethyl-3-aminopropyltrimethoxysilane hydrochloride, 3-ureidopropyltrimethoxysilane, 3-chloropropyltrimethoxysilane, 3-mercaptopropylmethyldimethoxysilane, 3-mercaptopropyltrimethoxysilane Bis (triethoxysilylpropyl) tetrasulfide, 3-isocyanatopropyltriethoxysilane and the like. These coating solutions may contain only one kind or two or more kinds.

The amount of the silane coupling agent contained in the coating solution is preferably 0.5 to 10% by mass relative to the total mass of components other than the solvent (organic solvent and water) contained in the coating solution. More preferably, it is mass%. If the amount of the silane coupling agent is too small, the adhesion between the resulting reflective layer and the substrate is not sufficiently increased, and if it is too large, the heat resistance may be lowered.

1-7. Other components The coating solution may contain components other than the white pigment, alkoxysilane compound, organic solvent, inorganic particles, clay mineral particles, silane coupling agent, metal alkoxide, or metal chelate as necessary. Good. For example, the coating liquid may contain water. However, the amount of water is preferably 20% by mass or less, more preferably 10% by mass or less, with respect to the total mass of the coating solution, from the viewpoint of storage stability and the like.

1-8. Preparation method of coating solution The preparation method of the coating solution may be a method of mixing raw materials such as white pigments, alkoxysilane compounds, organic solvents, inorganic particles, clay mineral particles, silane coupling agents, A method of mixing a plurality of raw materials in advance and mixing the mixed liquids later may be used. In order to enhance the thickening effect of inorganic particles and clay mineral particles, it is preferable to disperse one or both of inorganic particles and clay mineral particles in a solvent and then mix with the remaining components. The following method is mentioned as an example of the preparation method of a coating liquid.

A composition containing an alkoxysilane compound (oligomer) by mixing a bifunctional alkoxysilane compound, a trifunctional alkoxysilane compound, and a tetrafunctional alkoxysilane compound in an arbitrary ratio and polymerizing them in the presence of water, an organic solvent, and a catalyst. To prepare. On the other hand, a composition containing an organic solvent, inorganic particles, clay mineral particles, silane coupling agent and the like is prepared. And the composition containing an alkoxysilane compound, the composition containing an inorganic particle etc., and a white pigment are fully mixed, and a coating liquid is obtained.

Here, in order to improve the uniformity in the coating liquid, it is preferable to disperse all or part of the raw material of the coating liquid with the following apparatus. Moreover, in order to improve the dispersibility of a white pigment, it is preferable to disperse | distribute a white pigment at least once with the following apparatuses. When the white pigment is dispersed with the following apparatus, aggregation of the white pigment is reduced, and a denser and highly reflective coating film is obtained.

・ Mixing / dispersing device Mixing / dispersing of the mixed solution is, for example, a magnetic stirrer, an ultrasonic dispersing device, a homogenizer, a stirring mill, a blade kneading stirring device, a thin-film swirling type dispersing device, a high-pressure impact dispersing device, a rotation / revolution mixer, etc. Can be done.

All known devices can be used as the stirring device used for stirring the mixed solution. For example, Ultra Turrax (manufactured by IKA Japan), TK homomixer (manufactured by Primix), TK pipeline homomixer (manufactured by Primics), TK Philmix (manufactured by Primix), Claremix (manufactured by M Technique), Medialess stirrers such as Claire SS5 (manufactured by M Technique), Cavitron (manufactured by Eurotech), Fine Flow Mill (manufactured by Taiheiyo Kiko), Viscomill (manufactured by IMEX), Apex Mill (manufactured by Kotobuki Industries), Star mill (Ashizawa, manufactured by Finetech), DMPA / S Superflow (manufactured by Nihon Eirich), MP Mill (manufactured by Inoue Seisakusho), spike mill (manufactured by Inoue Seisakusho), Mighty mill (manufactured by Inoue Seisakusho), SC mill Media stirrers such as (Mitsui Mining Co., Ltd.) and Ultimate Chromatography (Sugino Machine Ltd.), Nanomizer (manufactured by Yoshida Kikai), and a high-pressure impact type dispersing device such as NANO 3000 (manufactured by Bitsubusha). In addition, a rotating / revolving mixer such as Awatori Nertaro (manufactured by Shinky Corp.) or an ultrasonic dispersing device can be suitably used.

-Viscosity of coating liquid The viscosity of the coating liquid measured at 25 ° C with a vibration viscometer is preferably more than 5 mPa · s and not more than 2000 mPa · s. An example of a vibration viscometer is VISCOMATE MODEL VM-10A (manufactured by Seconic). The above value is a value one minute after the vibrator is immersed in the liquid. If the viscosity of the coating solution exceeds 5 mPa · s, the white pigment will not easily settle. On the other hand, if it is 2000 mPa · s or less, the coating stability from various coating devices tends to increase.

1-9. Application Method and Curing Method The application method of the application liquid is not particularly limited, and may be an application method using a general application device such as a dispenser, a jet dispenser, an ink jet device, or a spray device. As described above, the coating liquid of the present invention is difficult to spread when wet on the substrate. Furthermore, since high surface tension is included in the organic solvent, it is difficult to scoop up the nozzle tip side surface of various coating apparatuses. Therefore, it is possible to stably discharge from a non-contact type discharge device (for example, a jet dispenser or an ink jet device).

Here, the coating liquid of the present invention is used after being applied to a desired region and then cured. The heating temperature for curing the coating solution is preferably 20 to 300 ° C., more preferably 25 to 200 ° C. If the heating temperature is less than 20 ° C, the solvent in the coating film may not be sufficiently evaporated. On the other hand, if the temperature exceeds 300 ° C., the LED element may be adversely affected. The drying / curing time is preferably from 0.1 to 120 minutes, more preferably from 5 to 60 minutes from the viewpoint of production efficiency.

2. LED Device FIG. 1 is a schematic cross-sectional view of an LED device 100 having a reflective layer made of a cured film of the aforementioned coating solution, and FIG. As described above, the LED device 100 includes the substrate 1, the LED element 2 disposed on the substrate 1, and the reflective layer 21 disposed at least around the LED element 2 on the substrate 1. Moreover, it further has the wavelength conversion layer 11 which covers the LED element 2 and the reflection layer 21 as needed.

The LED device 100 of the present invention has a reflective layer 21 that reflects the light emitted from the LED element 2 to the light extraction surface side. Therefore, the light extraction efficiency from the LED device 100 of the present invention is very high. Further, since the binder of the reflective layer 21 is polysiloxane, it is resistant to light and heat, and the reflective layer 21 is unlikely to deteriorate. Therefore, according to the LED device 100 of the present invention, high light extraction efficiency is maintained over a long period of time.

2-1. Substrate The substrate 1 preferably has insulating properties and heat resistance, and is preferably made of a ceramic resin or a heat resistant resin. Examples of the heat resistant resin include liquid crystal polymer, polyphenylene sulfide, aromatic nylon, epoxy resin, hard silicone resin, polyphthalic acid amide and the like.

The substrate 1 may contain an inorganic filler. The inorganic filler can be titanium oxide, zinc oxide, alumina, silica, barium titanate, calcium phosphate, calcium carbonate, white carbon, talc, magnesium carbonate, boron nitride, glass fiber, and the like.

The substrate 1 may have a cavity as shown in FIG. 1, but may have a flat plate shape.

In addition, an electrode 3 made of metal is formed on the substrate 1, and the electrode 3 has a function of supplying electricity to the LED element 2 from a power source (not shown) arranged outside the substrate 1. . The shape of the electrode 3 is not particularly limited, and is appropriately selected according to the type and application of the light emitting device 100. The method for producing the substrate 1 having the electrodes 3 is not particularly limited, and is generally obtained by integrally molding a lead frame having a desired shape and a resin.

2-2. LED Element The LED element 2 is an element that is electrically connected to the electrode 3 formed on the substrate 1 and emits light of a specific wavelength. In the LED device 100 shown in FIG. 1, the LED element 2 is disposed on the bottom surface 1 a of the truncated cone-shaped cavity (concave portion) of the substrate 1.

The wavelength of light emitted from the LED element 2 is not particularly limited. The LED element 2 may be, for example, an element that emits blue light (light of about 420 nm to 485 nm) or an element that emits ultraviolet light. Furthermore, an element that emits green light, red light, or the like may be used.

The configuration of the LED element 2 is not particularly limited. When the LED element 2 is an element that emits blue light, the LED element 2 includes an n-GaN compound semiconductor layer (cladding layer), an InGaN compound semiconductor layer (light emitting layer), and a p-GaN compound semiconductor layer. It may be a laminate of (clad layer) and a transparent electrode layer.

Further, the shape of the LED element 2 is not particularly limited, and may have, for example, a light emitting surface of 200 to 300 μm × 200 to 300 μm. The height of the LED element 2 is usually about 50 to 200 μm. The LED element 2 may be one in which light is extracted not only from the top surface but also from the side surface and the bottom surface. In the light emitting device 100 illustrated in FIG. 1, only one LED element 2 is disposed on the substrate 1, but a plurality of LED elements 2 may be disposed on the substrate 1.

The connection method between the LED element 2 and the electrode 3 is not particularly limited. For example, the LED element 2 and the electrode 3 may be connected via a metal wire 4 as shown in FIG. Moreover, the LED element 2 and the electrode 3 may be connected via a protruding electrode (not shown). A mode in which the LED element 2 and the electrode 3 are connected via the metal wire 4 is referred to as a wire bonding type. On the other hand, a mode in which the LED element 2 and the electrode 3 are connected via a protruding electrode is called a flip chip bonding type.

2-3. About the Reflective Layer The reflective layer 21 is a layer that reflects the emitted light from the LED element 2 and the fluorescence emitted by the phosphor contained in the wavelength conversion layer 11 to the light extraction surface side of the LED device 100. By providing the reflective layer 21, the amount of light extracted from the light extraction surface of the LED device 100 increases. The reflective layer 21 is obtained by applying and curing the above-described coating solution.

In the LED device 100 shown in FIG. 1, the reflective layer 21 is disposed on the substrate 1 excluding the region where the LED elements 2 are disposed. The reflective layer 21 is arranged in a mortar shape continuously from the bottom surface 1 a to the side surface 1 b of the truncated cone-shaped cavity (concave portion) of the substrate 1. The reflection layer 21 is formed in a ring shape concentric with the wavelength conversion layer 11 on the outer periphery of the wavelength conversion layer 11 in a top view.

The reflective layer 21 is formed on the surface of the substrate 1 at least outside the region where the LED elements 2 are arranged. The arrangement region of the LED element 2 refers to a light emitting surface of the LED element 2 and a connection portion between the LED element 2 and the electrode 3. That is, the reflective layer 21 is formed in a region that does not hinder the emission of light from the LED element 2 and the connection between the LED element 2 and the electrode 3.

As shown in FIGS. 1 and 2, when the substrate 1 has a cavity, it is preferable that the reflective layer 21 is also formed on the inner wall surface 1b of the cavity. This is because when the reflective layer 21 is formed on the cavity inner wall surface 1b, the light traveling in the horizontal direction on the surface of the wavelength conversion layer 11 can be reflected by the reflective layer 21 and extracted.

In the flip chip bonding type light emitting device 100, the reflective layer 21 may be formed in the gap between the LED element 2 and the substrate 1.

The thickness of the reflective layer 21 is preferably 5 to 30 μm, more preferably 5 to 20 μm. If the thickness of the reflective layer 21 exceeds 30 μm, cracks are likely to occur in the reflective layer 21. On the other hand, when the thickness of the reflective layer 21 is less than 5 μm, the light reflectivity of the reflective layer 21 is not sufficient, and the light extraction efficiency may not be increased. The thickness of the reflective layer 21 means the maximum thickness of the reflective layer 21 formed on the light emitting surface of the LED element 2. The thickness of the reflective layer 21 can be measured with a laser holo gauge.

2-4. Wavelength Conversion Layer The wavelength conversion layer 11 includes phosphor particles and a binder. The phosphor particles receive light (excitation light) emitted from the LED element 2 and emit fluorescence. By mixing the excitation light and the fluorescence, the color of the light from the LED device 100 becomes a desired color. For example, when the light from the LED element 2 is blue and the fluorescence emitted from the phosphor included in the wavelength conversion layer 11 is yellow, the light from the LED device 100 is white.

The wavelength conversion layer 11 may cover the LED element 2. For example, as shown in FIG. 1, the wavelength conversion layer 11 may cover the reflective layer 21 together with the LED element 2.

The phosphor particles contained in the wavelength conversion layer 11 may be anything that is excited by the light emitted from the LED element 2 and emits fluorescence having a wavelength different from that of the emitted light from the LED element 2. For example, examples of phosphor particles that emit yellow fluorescence include YAG (yttrium, aluminum, garnet) phosphors. The YAG phosphor receives blue light (wavelength 420 nm to 485 nm) emitted from the blue LED element, and emits yellow fluorescence (wavelength 550 nm to 650 nm).

The phosphor particles are, for example, 1) An appropriate amount of flux (fluoride such as ammonium fluoride) is mixed with a mixed raw material having a predetermined composition, and pressed to form a molded body. 2) The obtained molded body is packed in a crucible and fired in air at a temperature range of 1350 to 1450 ° C. for 2 to 5 hours to obtain a sintered body.

A mixed raw material having a predetermined composition is obtained by sufficiently mixing oxides such as Y, Gd, Ce, Sm, Al, La, and Ga, or compounds that easily become oxides at high temperatures in a stoichiometric ratio. . Moreover, the mixed raw material which has a predetermined composition mixes the solution which dissolved 1) the rare earth elements of Y, Gd, Ce, and Sm in the acid in stoichiometric ratio, and oxalic acid, and obtains a coprecipitation oxide. 2) It can also be obtained by mixing this coprecipitated oxide with aluminum oxide or gallium oxide.

The kind of the phosphor is not limited to the YAG phosphor, and may be another phosphor such as a non-garnet phosphor that does not contain Ce.

The average particle diameter of the phosphor particles is preferably 1 μm to 50 μm, and more preferably 10 μm or less. The larger the particle size of the phosphor particles, the higher the light emission efficiency (wavelength conversion efficiency). On the other hand, when the particle diameter of the phosphor particles is too large, a gap generated at the interface between the phosphor particles and the binder becomes large. Thereby, the intensity | strength of the cured film of a wavelength conversion layer tends to fall. The average particle diameter of the phosphor particles refers to the value of D50 measured with a laser diffraction particle size distribution meter. Examples of the laser diffraction particle size distribution measuring device include a laser diffraction particle size distribution measuring device manufactured by Shimadzu Corporation.

The binder contained in the wavelength conversion layer 11 can be a transparent resin or a translucent ceramic. The transparent resin can be, for example, a silicone resin and an epoxy resin. When the binder is a transparent resin, the thickness of the wavelength conversion layer 11 is preferably about 25 μm to 5 mm. If the wavelength conversion layer 11 is too thick, the concentration of the phosphor particles becomes excessively low, and the phosphor particles may not be uniformly dispersed. The thickness of the wavelength conversion layer 11 means the maximum thickness of the wavelength conversion layer 11 formed on the light emitting surface of the LED element 2. The thickness of the wavelength conversion layer 11 can be measured with a laser holo gauge. When the binder is a transparent resin, the amount of phosphor particles contained in the wavelength conversion layer 11 is generally 5 to 15% by mass.

On the other hand, the translucent ceramic may be the same as the polysiloxane contained in the reflective layer. When the binder is polysiloxane, the thickness of the wavelength conversion layer 11 is preferably 5 to 200 μm. When the binder is polysiloxane and the wavelength conversion layer 11 is excessively thick, cracks or the like are likely to occur in the wavelength change layer 11. Even when the binder is polysiloxane, the thickness of the wavelength conversion layer 11 means the maximum thickness of the wavelength conversion layer 11 formed on the light emitting surface of the LED element 2. The thickness of the wavelength conversion layer 11 can be measured with a laser holo gauge.

Further, when the binder is polysiloxane, the amount of phosphor particles contained in the wavelength conversion layer 11 is preferably 60 to 95% by mass. The higher the concentration of the phosphor particles contained in the wavelength conversion layer 11, the better. If the concentration of the phosphor particles is high, the strength of the wavelength conversion layer 11 tends to increase. However, if the content ratio of the translucent ceramic is too small, the phosphor particles may not be sufficiently retained.

3. Method for Manufacturing Light-Emitting Device The above-described light-emitting device can be manufactured through the following three steps.
(1) The process of preparing the board | substrate with which the LED element was mounted (2) The process of apply | coating the above-mentioned coating liquid around the board | substrate with which the LED element was arrange | positioned (3) The process of hardening a coating liquid

The manufacturing method of the light emitting device may include (4) a step of forming a wavelength conversion layer containing phosphor particles on the reflective layer as necessary.

(1) LED element preparation process In an LED element preparation process, the board | substrate with which the LED element and the electrode were connected is prepared. For example, it may be a step of preparing a substrate having the above-described electrodes, fixing the LED element to the substrate, and connecting the electrode of the substrate to the cathode electrode and the anode electrode of the LED element. The method for connecting the LED element and the electrode and the method for fixing the LED element to the substrate are not particularly limited, and may be the same as a conventionally known method.

(2) Coating liquid application process A coating liquid application process is a process of apply | coating a coating liquid to the area | region which forms the above-mentioned coating liquid on the board | substrate of the area | region around an LED element, ie, a reflection layer. The aforementioned coating solution is difficult to spread when wet on the substrate. Therefore, even if the coating liquid is applied to the vicinity of the outer periphery of the LED element, the coating liquid is difficult to adhere to the side surface of the LED element.

The method for applying the coating solution is not particularly limited as long as it is a method capable of applying the coating solution to a desired region, and known coating methods such as blade coating, spin coating coating, dispenser coating, spray coating, and inkjet method coating. It can be.

Here, since the above-mentioned coating liquid contains high surface tension, it is difficult to scoop up the nozzle tip side surface of various coating apparatuses. Therefore, it is possible to stably discharge from a non-contact type discharge device (for example, a jet dispenser or an ink jet device). In particular, it is preferable to discharge the coating liquid with a jet dispenser from the viewpoint that the coating liquid can be applied to a desired region.

(3) Coating liquid curing process The coating liquid curing process may be a process of heat curing the coating liquid. In the coating solution curing step, the solvent in the coating solution is removed and the alkoxysilane compound is hydrolyzed and polycondensed.

The temperature at which the coating solution is cured is preferably 20 to 300 ° C., more preferably 25 to 200 ° C. If the heating temperature is less than 20 ° C, the solvent in the coating film may not be sufficiently evaporated. On the other hand, if the temperature exceeds 300 ° C., the LED element may be adversely affected. The drying / curing time is preferably from 0.1 to 120 minutes, more preferably from 5 to 60 minutes from the viewpoint of production efficiency.

(4) Wavelength conversion layer formation process A wavelength conversion layer formation process may be a process of apply | coating and hardening the composition for wavelength conversion layers containing fluorescent substance particle so that an LED element may be covered. The composition for wavelength conversion layer contains phosphor particles and a binder component.

The binder component can be a transparent resin contained in the wavelength conversion layer or a precursor thereof, or a polysiloxane precursor (alkoxysilane compound). Moreover, a solvent is contained in the composition for wavelength conversion layers as needed. When the binder component is the aforementioned transparent resin or a precursor thereof, the solvent is a hydrocarbon such as toluene or xylene; a ketone such as acetone or methyl ethyl ketone; an ether such as diethyl ether or tetrahydrofuran; propylene glycol monomethyl ether acetate, ethyl It may be an ester such as acetate. On the other hand, when the binder component is an alkoxysilane compound, the solvent can be the same as the organic solvent contained in the coating solution.

The mixing of the composition for wavelength conversion layer can be performed, for example, with a stirring mill, a blade kneading stirring device, a thin-film swirling disperser, or the like. By adjusting the stirring conditions, the precipitation of the phosphor particles in the wavelength conversion layer composition is suppressed.

The method for applying the composition for wavelength conversion layer is appropriately selected depending on the type of binder, and can be, for example, dispenser application or spray application. Moreover, this is hardened after application | coating of the composition for wavelength conversion layers. The curing method and curing conditions of the wavelength conversion layer composition are appropriately selected depending on the type of resin. An example of the curing method is heat curing.

Hereinafter, the present invention will be described in more detail with reference to examples. However, the scope of the present invention is not limited by this.

<Preparation of alkoxysilane compound solution>
The catalyst used for the preparation of the alkoxysilane compound solution is as follows.
(Acid catalyst)
Hydrochloric acid Nitric acid Acetic acid ZC-150: Zirconium chelate (Orgatics ZC-150, manufactured by Matsumoto Fine Chemical)
TC-750: Titanium chelate (Orgatechs TC-750, manufactured by Matsumoto Fine Chemical)
D-25: Titanium alkoxide (D-25, manufactured by Shin-Etsu Chemical Co., Ltd.)
DX-9740: Aluminum chelate (DX-9740, manufactured by Shin-Etsu Chemical Co., Ltd.)

The organic solvents used for the preparation of the alkoxysilane compound solution are as follows.
(High surface tension organic solvent)
Ethylene glycol (EG), surface tension 48.4
Propylene glycol (PG), surface tension 35.3
1,3-butanediol (BD), surface tension 45.3
Ethylene glycol monomethyl ether (EGME), surface tension 31.8
Benzyl alcohol, surface tension 39
Triethylene glycol, surface tension 45.2
Diacetone alcohol, surface tension 31

(Low surface tension organic solvent)
Isopropyl alcohol (IPA), surface tension 21.7
n-butanol (n-BuOH), surface tension 24.6
Methanol, surface tension 22.6
Ethanol, surface tension 22.55
Methyl-3-methoxypropionate (MMP)

(Preparation of alkoxysilane compound solution 1)
Tetramethoxysilane 7.8% by mass, methyltrimethoxysilane 2.2% by mass, propylene glycol 35% by mass, methanol 35% by mass, water 9.99% by mass, and nitric acid 0.01% by mass. Mix and stir at 23 ° C. for 3 hours. Then, it was made to react, stirring at 26 degreeC for 3 days, and the alkoxysilane compound solution 1 containing a polysiloxane oligomer was obtained.

(Preparation of

alkoxysilane compound solutions

2, 3, 5 to 20)
Except for changing the types and amounts of the tetrafunctional alkoxysilane compound, trifunctional alkoxysilane compound, bifunctional alkoxysilane compound, solvent, water, and catalyst during preparation of the alkoxysilane compound to those shown in Table 1, alkoxysilane Prepared in the same manner as for Compound Solution 1.

(Preparation of alkoxysilane compound solution 4)
An alkoxysilane compound solution 4 was prepared by mixing 20% by mass of triethoxysilane, 35% by mass of 1,3-butanediol, 35% by mass of methanol, 9.99% by mass of water, and 0.01% by mass of hydrochloric acid. Obtained.

(Preparation of alkoxysilane compound solution 21)
Water and dilute nitric acid were added to 0.1 mol of ethyltrimethoxysilane, and the molar ratio of alkoxide: water: dilute nitric acid was adjusted to 1: 3: 0.002. This solution was stirred in a sealed container at 20 ° C. for 3 hours, and further aged at 60 ° C. for 48 hours to proceed with a hydrolysis reaction and a polycondensation reaction. The upper phase containing methanol produced | generated by reaction was removed, and the alkoxysilane compound was obtained by making it dry at 60 degreeC for 3 hours. The alkoxysilane compound was diluted with 1,3-butanediol and n-butanol (1/1) to 20% by mass to obtain an alkoxysilane compound solution 21.

(Evaluation)
The molecular weight of the polysiloxane oligomer in each alkoxysilane compound solution was measured by GPC. Further, when solid Si-NMR was measured using a solid obtained by curing this solution at 150 ° C. for 1 hour as a sample, peaks derived from the Q component and the T component were observed. And the ratio of T component (R4 / R3) and the amount of D component (R2) were calculated.

(Preparation of adjustment liquids 1 to 26)
Each component was blended in the component ratio shown in Table 2, and when two or more components were contained, the mixture was stirred with a stirrer. Each component used for preparation of the adjustment liquid is as follows.

(High surface tension organic solvent)
BD: 1,3-butanediol, surface tension 45.3
PG: Propylene glycol, surface tension 35.3

(Low surface tension organic solvent)
n-BuOH: n-butanol, surface tension 24.6
IPA: isopropyl alcohol, surface tension 21.7
EtOH: ethanol, surface tension 22.55

(Inorganic particles)
Silicia 470: Silica (Silicia 470, manufactured by Fuji Silysia Chemical) average particle size of 14 μm
VM2270: Silica (VM-2270, manufactured by Dow Corning) average particle size of 5 to 15 μm
SP-1: Silica (Microbead SP-1, manufactured by JGC Catalysts & Chemicals) Average particle diameter of 5 μm
SS-50F: Silica (Nip seal SS-50F, manufactured by Tosoh Silica) Average particle size 1.2 μm
Alu-C: Alumina (AEROXIDE Alu-C, Nippon Aerosil) average primary particle size 13 nm
A300: Silica (Nippon Aerosil Co., Ltd.) average primary particle size: 7 nm
RX300: Silica (manufactured by Nippon Aerosil Co., Ltd.) Average primary particle size: 7 nm
F3: Silica (high silica F3, manufactured by Nichetsu) average particle diameter of 3 μm
ZR-210: ZrO ₂ particles (TECNADIS-Zr-210, manufactured by TECNAN) average particle diameter of 10 to 15 nm
Ti-210: TiO ₂ particles (TECNADIS-TI-210, manufactured by TECNAN) average particle diameter of 10 to 15 nm

(Clay mineral particles)
MK-100: Synthetic mica (Micromica MK-100, manufactured by Corp Chemical)
ME-100: Synthetic mica (Somasif ME-100, manufactured by Corp Chemical)
SWN: Smectite (Lucentite SWN, manufactured by Corp Chemical)
SPN: Smectite (Lucentite SPN, manufactured by Corp Chemical)
Kunipia F: Montmorillonite (Kunipia F, manufactured by Kunimine Industries)
FSE: Sericite (Sericite FSE, manufactured by Sanshin Mining Co., Ltd.)
SA-1: Saponite-like substance (Smecton SA-1, manufactured by Kunimine Industries)
HVP: Natural bentonite (Esven NE, manufactured by Hojun Co.)
NE: Bentonite (Bengel HVP, manufactured by Hojun Co.)
Imogolite: The one prepared by the method described below was used

(Silane coupling agent)
KBM-403: 3-glycidoxypropyltrimethoxysilane (KBM-403, manufactured by Shin-Etsu Silicone)
KBM-903: 3-aminopropyltrimethoxysilane (KBM-903, manufactured by Shin-Etsu Silicone)
KBM-802: 3-mercaptopropylmethyldimethoxysilane (KBM-802, manufactured by Shin-Etsu Silicone)
KBE-846: Bis (triethoxysilylpropyl) tetrasulfide (KBE-846, manufactured by Shin-Etsu Silicone)

-Preparation method of imogolite Sodium orthosilicate was dissolved in ion-exchanged water to prepare 10 L of a 3.0 mM sodium orthosilicate aqueous solution. The obtained sodium orthosilicate aqueous solution was ion-exchanged by flowing into a cation exchange resin packed in a column to obtain a 3.0 mM orthosilicate aqueous solution. The flow rate of the column was set so that the electrical conductivity of the resulting orthosilicate aqueous solution was 500 μS / cm or less. The electrical conductivity of the orthosilicate aqueous solution was measured at 25 ° C. using an electrical conductivity meter ES-51 (manufactured by Horiba, Ltd.).
As the cation exchange resin, Amberlite IR120B (manufactured by Organo), which is a strongly acidic cation exchange resin, was used so that the pH of the orthosilicate aqueous solution was 5.0. The pH of the aqueous orthosilicate solution was measured by the above method using MODEL (F-71S) (Horiba, Ltd.).

2 L of 3.0 mM orthosilicate aqueous solution obtained by the above method, 1 L of 30 mM aluminum nitrate aqueous solution, 1 L of 28 mM urea aqueous solution, 1 L of 3.8 mM NaOH aqueous solution, 2 L of ion-exchanged water, The mixed solution was prepared so that the molar concentration of Si and Al was 1: 2. Further, 4M NaOH aqueous solution was added dropwise so that the pH of the mixed solution was 3.5. The pH of the prepared mixed solution was measured by the same method as described above. After sufficiently stirring the prepared mixed solution, the mixed solution was heated at 100 ° C. for 80 hours in an autoclave.
After returning the mixture to room temperature, 1/10 volume of a 5M NaCl aqueous solution was added to the mixture to cause gelation, followed by centrifugation to obtain a transparent tubular aluminum silicate gel. The salt (NaCl) contained in the obtained gel was removed using a dialysis membrane to obtain an aqueous dispersion of tubular aluminum silicate. Further, the aqueous dispersion was heated at 100 ° C. to evaporate the water, and further heated at 200 ° C. for 1 hour to obtain a powder of tubular aluminum silicate (imogolite).

[Examples 1 to 54 and Comparative Examples 1 to 4]
The white pigment, the silane compound solution, and the adjustment liquid were mixed at the mixing ratios shown in Tables 3 to 6. And the said mixture was stirred with the stirring apparatus, and the coating liquid was prepared. The following white pigments were used. Tables 3 and 4 show the concentration of each component in the coating solution, and show the evaluation results of the viscosity of the coating solution, the coating amount stability, and the fine line reproducibility. Each measuring method is shown below. On the other hand, Tables 5 and 6 show the concentration of each component in the reflective layer obtained by curing the coating liquid, the presence or absence of cracks in the reflective layer obtained by curing the coating liquid, the reflectance of the reflective layer, And the result of a tape peeling test is shown. Each measuring method is shown below. In Tables 3 to 6, the amount of the high surface tension solvent is the amount of the high surface tension solvent relative to the total amount of the organic solvent contained in the coating solution.

(White pigment)
CR-93: Titanium oxide, manufactured by Ishihara Sangyo CR-95: Titanium oxide, manufactured by Ishihara Sangyo SX-3103: Titanium oxide, manufactured by Sakai Chemical Industry D-918: Titanium oxide, manufactured by Sakai Chemical Industry JR: Titanium oxide, manufactured by Teika JR-405: Titanium oxide, manufactured by Teika HD-11: Aluminum oxide, manufactured by Nikkato NFJ-3: Barium sulfate (NFJ-3-1999), manufactured by Sansai Bussan AP-100S: Boron nitride, manufactured by MARUKA

<Viscosity evaluation>
The viscosity of the coating solution was measured using a vibration viscometer VISCOMATE MODEL VM-10A (manufactured by Seconic). The measurement temperature was 25 ° C., and the measured value after 1 minute was used after the vibrator was immersed in the liquid.

<Evaluation of coating amount stability>
For the coating amount stability, a jet dispenser AeroJet (manufactured by Musashi Engineering Co., Ltd.) was used to fill the syringe with the coating liquid, and line drawing was performed 10 times continuously under certain conditions. And the total mass of the dripped liquid was calculated | required. Subsequently, the same operation was performed every 10 minutes while holding the syringe as it was, and after 4 hours, 10 lines were continuously drawn under the same conditions to obtain the total mass of the dropped liquid.
The mass change rate was calculated by the following formula.
Mass change rate = ((BA) / A) × 100%
In the above formula, A is the total mass of the liquid dropped in the first 10 times, and B is the total mass of the liquid dropped in 10 times after 4 hours.
Based on the mass change rate, the coating amount stability was evaluated as follows.
○: Mass change rate was less than 3% Δ: Mass change rate was 3% or more and less than 6%

<Evaluation of fine line reproducibility>
The fine line reproducibility of the coating liquid was such that a jet dispenser AeroJet (manufactured by Musashi Engineering Co., Ltd.) was used to fill the syringe with the coating liquid, and the coating liquid was applied linearly on a silver plate. The drawn line width was measured and evaluated as follows.
A: Line width was less than 300 μm B: Line width was 300 μm or more and less than 400 μm Δ: Line width was 400 μm or more and less than 500 μm ×: Line width was 500 μm or more

<Evaluation of film formability (cracks during film formation)>
A coating solution was applied on a silver plate and cured by heat treatment at 150 ° C. for 1 hour to prepare a measurement sample having a reflective layer having a thickness of 20 μm. The state of the reflective layer at this time was visually observed and judged as follows.
○: No crack was observed in the reflective layer. Δ: A slight crack occurred in the reflective layer, but the reflective layer was not missing. ×: A crack occurred in the reflective layer, and a part of the reflective layer was a substrate. Missing from

<Reflectance measurement>
The coating solution was applied to a transparent 1 mm glass plate and cured by heat treatment at 150 ° C. for 1 hour to prepare a measurement sample having a reflective layer having a thickness of 20 μm. Then, the reflectance of each sample was measured with a spectrophotometer V-670 (manufactured by JASCO Corporation). The evaluation results were judged as follows.
○: Reflectance at a wavelength of 500 nm was 95% or more Δ: Reflectance at a wavelength of 500 nm was 90% or more and less than 95% ×: Reflectance at a wavelength of 500 nm was less than 90%

<Tape peeling experiment>
A coating solution was applied on a silver plate and cured by heat treatment at 150 ° C. for 1 hour to prepare a measurement sample having a reflective layer having a thickness of 20 μm. The work of attaching Nichiban cello tape (registered trademark) (24 mm) to the formed reflective layer and immediately peeling it off was repeated 20 times. And the state of the reflective layer was observed with the microscope for every operation | work, and it judged as follows.
A: No peeling of reflective layer was observed after 20 times of operation, and nothing adhered to the surface of the tape. ○: No separation was observed after 10 times of operation, but after 20 times of operation, it was slightly peeled off. △: No peeling occurred, but after the first work, a small amount of white pigment powder adhered to the surface of the tape. X: The reflective layer was peeled off at the 10th working time.

As shown in Tables 3 and 4, when the amount of the high surface tension solvent relative to the total amount of the organic solvent was 45% by mass or more, the fine line reproducibility evaluation of the coating solution was good (Example 1). To 54 and Comparative Examples 1, 2, 4). It is inferred that the coating liquid was difficult to wet and spread on the substrate (silver plate) due to the high surface tension solvent. However, as shown in Table 6, when the amount of the high surface tension solvent exceeded 90% by mass, fine line reproducibility was good, but cracks occurred in the cured film (Comparative Example 4). Since the amount of the high surface tension solvent was large and the organic solvent was difficult to volatilize, the solvent was volatilized from the inside of the coating film after polymerization of the alkoxysilane on the coating film surface, and it was assumed that cracks occurred in the cured film.

Further, as shown in Table 6, even when the amount of the high surface tension solvent was 45 to 90% by mass, when R4 / R3 exceeded 3, cracks occurred in the cured film (Comparative Example). 1). Since the amount of tetrafunctional alkoxysilane is large and the crosslink density of polysiloxane is excessively increased, it is presumed that distortion occurred during curing. On the other hand, when R2 exceeded 40, the adhesion between the cured film and the substrate was low (Comparative Example 2). It is presumed that the amount of the bifunctional alkoxysilane was large, and it was difficult to sufficiently bond the siloxane to the polysiloxane in the cured film and the OH group or the like on the substrate surface.

Furthermore, as shown in Tables 3 and 4, when the viscosity of the coating solution was more than 5 mPa · s, the stability evaluation of the coating amount increased (Examples 2 to 54 and Comparative Examples 1 to 4). It is inferred that the white pigment was difficult to settle in the coating solution. On the other hand, when the viscosity of the coating solution was 2000 mPa · s or less, the evaluation of fine line reproducibility was likely to increase (Examples 1 to 10 and Examples 12 to 54).

Further, as shown in Tables 5 and 6, when an oligomer was included in the alkoxysilane compound (alkoxysilane compound solution 1 to 3, or 5 to 21), the resulting reflective layer was hardly cracked (Examples) 1-14 and Examples 16-54). It is presumed that the alkoxysilane compound is polymerized in advance, so that the volume shrinkage during the hydrolysis / polycondensation reaction is small and the film is hardly distorted. On the other hand, when the silane compound was used without being polymerized in advance, a slight crack was generated due to volume shrinkage during the hydrolysis / polycondensation reaction (Example 15).

Further, when the white pigment content was low (less than 50% by mass), the reflectance was slightly lower than when the white pigment was 50% by mass or more (the reflectance of Example 10). ). On the other hand, when the white pigment content was too high (over 95% by mass), the binder was relatively insufficient, and a slight amount of powder was seen from the surface (tape peeling in Example 13).

Furthermore, when the inorganic particles contained in the coating liquid are metal oxide fine particles having an average particle size of 5 nm or more and less than 100 nm, the adhesion of the resulting reflective layer and the adhesion between the substrate and the substrate due to the anchor effect of the metal oxide fine particles The property (evaluation of the tape test) was likely to increase (Examples 3, 5, 9, 10, 11).
In addition, when the coating solution contained a silane coupling agent, adhesion to the substrate (evaluation of the tape test) was likely to increase (Examples 7 to 9, 14, 15, 21, 23, 24).

This application claims priority based on Japanese Patent Application No. 2014-197074 filed on September 26, 2014. The contents described in this application specification and the drawings are all incorporated herein by reference.

The coating liquid of the present invention can be applied to a desired region with high definition. In addition, the reflective layer obtained by curing the coating solution is less deteriorated and can efficiently reflect light over a long period of time. Therefore, it is very useful as a composition for forming a reflective layer of an LED device.

DESCRIPTION OF SYMBOLS 1 Substrate 2 LED element 3 Electrode 11 Wavelength conversion layer 21 Reflective layer 100 LED device

Claims

A coating liquid containing a white pigment, an alkoxysilane compound, and an organic solvent,
The ratio of the bifunctional alkoxysilane compound to the total amount of the alkoxysilane compound is R2 (mol%), the ratio of the trifunctional alkoxysilane compound is R3 (mol%), the ratio of the tetrafunctional alkoxysilane compound is R4 (mol%), (However, the total of R2, R3, and R4 is 100 mol%), satisfying both conditions of the following formula 1 and formula 2,
0 ≦ R2 <40 (Formula 1)
0 ≦ R4 / R3 ≦ 3 (Formula 2)
The coating solution, wherein the organic solvent contains 45 to 90% by mass of a high surface tension organic solvent having a surface tension of 30 mN / m or more at 25 ° C. with respect to the total amount of the organic solvent.
The coating according to claim 1, wherein the high surface tension organic solvent is selected from the group consisting of monohydric alcohols, polyhydric alcohols, ketone solvents, ester solvents, amine solvents, amide solvents, and sulfur-containing solvents. liquid.
The coating liquid according to claim 1 or 2, wherein at least a part of the alkoxysilane compound is a polymer of a bifunctional alkoxysilane compound, a trifunctional alkoxysilane compound, or a tetrafunctional alkoxysilane compound.
The coating solution according to any one of claims 1 to 3, further comprising inorganic particles or clay mineral particles.
The coating solution according to any one of claims 1 to 4, further comprising a silane coupling agent.
6. The coating liquid according to claim 1, wherein the viscosity measured at 25 ° C. with a vibration viscometer is more than 5 mPa · s and not more than 2000 mPa · s.
The coating solution according to any one of claims 1 to 6, comprising a white pigment in an amount of 50 to 95% by mass based on the total mass of the solid content after heat curing.
A method for manufacturing an LED device, comprising: a substrate; an LED element disposed on the substrate; and a reflective layer formed around the LED element,
A method for manufacturing an LED device, comprising: applying and curing the coating solution according to any one of claims 1 to 7 around the substrate on which the LED elements are arranged.
The method for manufacturing an LED device according to claim 8, wherein the coating liquid is applied by a non-contact type discharge device.
The method for manufacturing an LED device according to claim 9, wherein the discharge device is a jet dispenser.
An LED device comprising: a substrate; an LED element disposed on the substrate; and a reflective layer formed on the substrate around the LED element,
An LED device, wherein the reflective layer is a cured film of the coating liquid according to any one of claims 1 to 7.
The LED device according to claim 11, wherein the reflective layer is further formed between the substrate and the LED element.