KR20220055451A - Photocurable composition and its cured product, sealing material, protective material, waterproof structure and manufacturing method of the cured product - Google Patents

Abstract

[상기 식(1) 중, a^* ₀ 및 b^* ₀는, 경화 전의 L^*a^*b^* 색공간에서의 색도 a^*값 및 b^*값을 나타내고, a^* ₅₀ 및 b^* ₅₀은, 경화율 50%에서의 L^*a^*b^* 색공간에서의 색도 a^*값 및 b^*값을 나타내고, a^* ₁₀₀ 및 b^* ₁₀₀은, 경화 후에서의 L^*a^*b^* 색공간에서의 색도 a^*값 및 b^*값을 나타낸다.]Provided is a photocurable composition in which a color change distinguishable from that before curing after completion of curing is obtained. At least one acrylic compound selected from an acrylic monomer, an acrylic oligomer and an acrylic polymer, a photoradical generator, and a leuco dye, as defined in CIE1976 (L ^* , a ^* , b ^* ) color space described in JISZ8781-4 The chromaticity difference ΔE between the uncured color values (L ^* ₀ , a ^* ₀ , b ^* ₀ ) and the cured color values (L ^* ₁₀₀ , a ^* ₁₀₀ , b ^* ₁₀₀ ) is 10 or more, The displayed chromaticity change parameter was set as the photocurable composition in the range of 0-2.0.

[In the formula (1), a ^* ₀ and b ^* ₀ represent the chromaticity a ^* value and b ^* value in the L ^* a ^* b ^* color space before curing, and a ^* ₅₀ and b ^* ₅₀ are L * a * b * chromaticity in L ^* a ^* b ^* color space at a rate of 50% represents a ^* value and b ^* value, where a ^* ₁₀₀ and b ^* ₁₀₀ are chromaticity in L ^* a ^* b ^* color space after curing a ^* values and b ^* values.]

Description

Photocurable composition and its cured product, sealing material, protective material, waterproof structure and manufacturing method of the cured product

The present invention relates to a photocurable composition, a cured product thereof, and the like, and a method for producing the same.

The photocurable composition which is liquid before application and can use the cured body photocured after application|coating as a gasket etc. is used after application|coating to a desired site|part, and hardening enough. However, for example, in the case of non-curing due to a process error or insufficient curing due to deterioration of the UV lamp, the uncured photo-curable composition is contaminated by contact with the contact body, or the curing is insufficient. It was commercialized, and there was a fear that the product could be defective due to a decrease in compression permanent non-uniformity.

The problem is that the change in the external size before and after curing of the photocurable composition is small and it is difficult to immediately detect whether curing has been completed. The technology has been developed and is described, for example, in International Publication No. 2016/129568 (Patent Document 1).

International Publication No. 2016/129568

However, in the technique described in International Publication No. 2016/129568 (Patent Document 1), the cured state of the photocurable composition and color change do not necessarily correspond, and it cannot be said that the color change indicates the end of curing. Moreover, when the dye concentration was high, it became difficult for light rays, such as an ultraviolet-ray, to reach the inside, and there existed a possibility that sclerosis|hardenability was impaired.

The present invention has been made in order to solve such a problem. That is, while coloring with a low concentration of leuco dye, there is provided a photocurable composition in which a color change distinguishable from that before curing after completion of curing is obtained.

The photocurable composition of this invention which achieves the said objective, and its hardening body are as follows. That is, the present invention includes at least one acrylic compound selected from an acrylic monomer, an acrylic oligomer and an acrylic polymer, a photoradical generator, and a leuco dye, and CIE1976 (L ^* , a ^* , b ^* described in JISZ8781-4) ) The chromaticity difference ΔE between the uncured color value (L ^* ₀ , a ^* ₀ , b ^* ₀ ) and the cured color value (L ^* ₁₀₀ , a ^* ₁₀₀ , b ^* ₁₀₀ ) defined in the color space is 10 or more, A photocurable composition having a chromaticity change parameter represented by formula (1) in the range of 0 to 2.0 is provided.

[Formula 1]

[In the formula (1), a ^* ₀ and b ^* ₀ represent the chromaticity a ^* value and b ^* value in the L ^* a ^* b ^* color space before curing, and a ^* ₅₀ and b ^* ₅₀ are L * a * b * chromaticity in L ^* a ^* b ^* color space at a rate of 50% represents a ^* value and b ^* value, where a ^* ₁₀₀ and b ^* ₁₀₀ are chromaticity in L ^* a ^* b ^* color space after curing a ^* values and b ^* values.]

The present invention includes at least one acrylic compound selected from an acrylic monomer, an acrylic oligomer, and an acrylic polymer, a photo radical generator, and a leuco dye, so that at least one selected from an acrylic monomer, an acrylic oligomer and an acrylic polymer by irradiation with light of acrylic compound can be cured, and also can change the chromaticity before and after curing. In addition, the uncured color values (L ^* ₀ , a ^* ₀ , b ^* ₀ ) and the color values after curing (L ^* ₁₀₀ , a) defined in CIE1976 (L ^* , a ^* , b ^* ) color space described in JISZ8781-4 ^* ₁₀₀ , b ^* ₁₀₀ ) has a chromaticity difference ΔE of 10 or more, so the change in chromaticity before and after curing is large, and the difference is easy to understand.

[Equation 2]

[In the formula (1), a ^* ₀ and b ^* ₀ represent the chromaticity a ^* value and b ^* value in the L ^* a ^* b ^* color space before curing, and a ^* ₅₀ and b ^* ₅₀ are L * a * b * chromaticity in L ^* a ^* b ^* color space at a rate of 50% represents a ^* value and b ^* value, where a ^* ₁₀₀ and b ^* ₁₀₀ are chromaticity in L ^* a ^* b ^* color space after curing a ^* values and b ^* values.]

In addition, since the chromaticity change parameter expressed by the above formula (1) is in the range of 0 to 2.0, the distance (color change) in the latter half of the reaction becomes at least half of the first half of the reaction. can be prevented Incidentally, the chromaticity difference and chromaticity change parameters in the present invention are values measured and calculated by the methods described in Examples.

This invention can be set as the photocurable composition which does not contain an acid generator. The photocurable composition which does not contain an acid generator does not cause an early color change to the leuco dye, and it is easy to respond|correspond to the hardening of an acrylic monomer, an acrylic oligomer, and an acrylic polymer, and the reaction by a leuco dye.

In this invention, the said acrylic compound can be set as the photocurable composition which is at least any one of a monofunctional acrylic monomer, a bifunctional or more than bifunctional acrylic oligomer, and a bifunctional or more than functional acrylic polymer. The photocurable composition in which the acrylic compound is at least one of a monofunctional acrylic monomer, a bifunctional or higher functional acrylic oligomer, and a bifunctional or higher functional acrylic polymer, the cured product obtained by curing it, adheres to an electronic device or a substrate, and is waterproof Since it expresses etc., it can use as a preferable sealing material, a protective material, etc.

The present invention can provide a photocurable composition in which the acrylic compound contains at least a monofunctional acrylic monomer and further contains a styrenic elastomer. The photocurable composition in which the said acrylic compound contains at least a monofunctional acrylic monomer, and also contains a styrenic elastomer can provide rubber elasticity while reducing transparency of a hardening body and increasing its mechanical strength.

In the present invention, the styrenic elastomer is at least one of a high molecular weight styrenic elastomer, an epoxy-modified styrenic elastomer, and a styrenic elastomer having an unsaturated bond in the soft segment in terms of a weight average molecular weight of 200,000 or more It can be a photocurable composition there is. The photocurable composition, wherein the styrenic elastomer is at least any one of a high molecular weight styrene-based elastomer, an epoxy-modified styrene-based elastomer, and a styrenic elastomer having an unsaturated bond in the soft segment with a weight average molecular weight of 200,000 or more Compression permanent distortion can be made small, and it can be used suitably as a sealing material, a protective material, etc.

The present invention can be a photocurable composition in which the styrene-based elastomer is a styrene-isobutylene-styrene block polymer. The photocurable composition in which the styrenic elastomer is a styrene-isobutylene-styrene block polymer reduces the transparency of the cured product and can impart rubber elasticity while increasing its mechanical strength, so that it can be used as a protective material such as a sealing material. It can be used preferably.

This invention can be set as the photocurable composition which further contains inorganic powder. The photocurable composition further containing inorganic powder imparts thixotropy to the photocurable composition and has shape stability after application, so it can be preferably used as a sealing material, a protective material such as a sealing material, and a masking material.

According to the present invention, a cured product obtained by curing any one of the above photocurable compositions in which ΔE changes by 20 or more when immersed in 1N hydrochloric acid at 70°C for 120 hours. A cured product obtained by curing any of the above photocurable compositions in which ΔE changes by 20 or more when immersed in 1N hydrochloric acid at 70°C for 120 hours does not contain an acid generating material. Such a hardening body is preferable at the point with little possibility of corroding to-be-adhered bodies, such as a board|substrate, wiring, an electronic element, and a housing, by residual acid.

The present invention can be a cured body having a Martens hardness of 0.005 to 50 N/mm ² measured by a nanoindentation test. A cured body having a Martens hardness of 0.005 to 50 N/mm ² measured by a nanoindentation test has excellent balance of flexibility, extensibility, and compressibility, and is preferable as a sealing material, a protective material such as a sealing material, and a masking material can be used readily.

In the present invention, the cured product or the cured product of any one of the above photocurable compositions can be a sealing material having a compression set of 50% or less. The cured product or the cured product of any of the above photocurable compositions has a compression set of 50% or less, so that it can be used as a sealing material such as a gasket having excellent sealing properties.

In the present invention, the cured product of any one of the above photocurable compositions or the cured product of any of the above can be used as a protective material for covering an electronic element or wiring on a substrate. As the cured product of any one of the above photocurable compositions or the cured product of any of the above, the protective material covering the electronic device or wiring on the substrate is an excellent protective material having predetermined flexibility and flexibility.

The present invention includes a case having an opening, a cover body for closing the opening, and the sealing material provided on at least one of the case and the cover body, wherein by fitting the case and the cover body It can be set as the waterproof structure in which the said sealing material compresses and seals the said opening liquid-tightly. The present invention comprises a case having an opening, a cover body for closing the opening, and the sealing material provided on at least one of the case and the cover body, wherein the case and the cover body are fitted by fitting. Since the said sealing material was set as the waterproof structure which compressively deforms and seals the said opening liquid-tightly, it is a waterproof structure excellent in sealing property.

The present invention provides at least one cured product selected from a sealing material, a protective material, a masking material, an adhesive, and a vibration-proof material, comprising at least a step of applying any one of the photocurable compositions and a step of irradiating an activation energy ray. It can be done by the manufacturing method of The present invention provides a method for manufacturing at least one cured body selected from a sealing material, a protective material, a masking material, an adhesive, and a vibration-proof material, comprising at least a step of applying the photocurable composition of any one of the above and a step of irradiating an activation energy ray Therefore, it is easy to manufacture these hardened bodies.

In the photocurable composition of the present invention, after the end of photocuring, a color change distinguishable from that before curing is obtained. Moreover, the hardening body of the photocurable composition of this invention can be utilized for various uses, such as an adhesive agent, a masking material, a gasket, a sealing material, and a sealing material.

BRIEF DESCRIPTION OF THE DRAWINGS It is explanatory drawing explaining the measurement procedure of chromaticity.

[Photocurable composition]

EMBODIMENT OF THE INVENTION This invention is demonstrated in detail based on embodiment. The photocurable composition of the present invention is composed of a composition comprising at least one acrylic compound selected from an acrylic monomer, an acrylic oligomer and an acrylic polymer, a photoradical generator, and a leuco dye, CIE1976 described in JISZ8781-4 ( Chromaticity of uncured color values (L ^* ₀ , a ^* ₀ , b ^* ₀ ) and cured color values (L ^* ₁₀₀ , a ^* ₁₀₀ , b ^* ₁₀₀ ) defined in the L ^* , a ^* , b ^* ) color space The difference ΔE is 10 or more, and the chromaticity change parameter expressed by the following formula (1) is in the range of 0 to 2.0.

[Equation 3]

[In the formula (1), a ^* ₀ and b ^* ₀ represent the chromaticity a ^* value and b ^* value in the L ^* a ^* b ^* color space before curing, and a ^* ₅₀ and b ^* ₅₀ are L * a * b * chromaticity in L ^* a ^* b ^* color space at a rate of 50% represents a ^* value and b ^* value, where a ^* ₁₀₀ and b ^* ₁₀₀ are chromaticity in L ^* a ^* b ^* color space after curing a ^* values and b ^* values.]

"Before curing" of the photocurable composition refers to a state before a photocuring reaction such as ultraviolet irradiation in a state in which the components forming the photocurable cured body are mixed, and "after curing" means that the photocurable composition is photocured It refers to a state that has been cured under conditions that can sufficiently complete the reaction. However, in consideration of the occurrence of cases in which curing is not recognized sufficiently, in the examples to be described later, “after curing” is a state that is cured by irradiating light for curing under the condition of an accumulated light amount of 15000 mJ/cm ² , The change in the peak height when the infrared absorption spectrum is measured by the FT-IR method is shown in a substantially saturated state.

The photocurable composition has an uncured color value (L ^* ₀ , a ^* ₀ , b ^* ₀ ) defined in CIE1976 (L ^* , a ^* , b ^* ) color space described in JISZ8781-4 and a color value after curing (L ^* ₁₀₀ , a ^* ₁₀₀ , b ^* ₁₀₀ ) has a chromaticity difference ΔE of 10 or more, so the color change between the uncured state and the cured state is clear and the difference can be recognized. When ΔE is 20 or more, the color change is larger, which is preferable, and when ΔE is 30 or more, the color change in the latter half of the reaction becomes large even when the chromaticity change parameter is large, so it is particularly preferable. On the other hand, when ?E is less than 10, the color change before and after curing is small, and there is a fear that it may be difficult to determine whether or not curing has been completed.

The numerator of the formula (1) is a ^* , b ^* coordinates of the chromaticity of the cured state with a curing rate of 50% from the coordinates of the uncured chromaticity on the plane (a ^* ₀ , b ^* ₀ ) (a ^* ₅₀ , b ^* ₅₀ ) represents the distance, and the denominator of formula (1 ⁾ is a ^* , b ^* _{After curing} ⁽ The distance to the coordinates (a ^* ₁₀₀ , b ^* ₁₀₀ ) of the chromaticity of the cured state of the curing rate of 100%) is shown. Therefore, Equation (1) is, with respect to the distance (color change) when the curing rate of the photocurable composition is from 0% to 50% (in the first half of the reaction), when the curing rate is from 50% to 100% (the latter half of the reaction) ) is the ratio of the distance (color change). Let this be a chromaticity change parameter. And, since the value of Equation (1), that is, the chromaticity change parameter is in the range of 0 to 2.0, the color change in the second half of the reaction is the smallest when the value is 2.0, and the color change in the second half of the reaction is larger as it approaches 0 ( or the color change in the first half of the reaction is small), and the distance (color change) in the second half of the reaction is at least half greater than the first half of the reaction. From the viewpoint of a large color change in the latter half of the reaction, the chromaticity change parameter is preferably 0 to 1.0, particularly preferably 0 to 0.5.

Although the phenomenon of different chromaticity due to curing of an object has been known before, the degree of curing of the photocurable composition and the degree of color change do not necessarily coincide. There were many. For this reason, although hardening was not complete|finished, the color change occurred, and there was also a case where it was mistakenly considered that hardening was performed on the contrary. However, in the present invention, since the state of color change is divided into two in a state where the curing rate of the photocurable composition is 50%, in addition to being able to emphasize the size of the color change during the remaining 50% curing in the latter half of the reaction, the formula Since the case where the value of (1) is in the range of 0 to 2.0 is set, it becomes possible to exclude the case where most of the color change is completed throughout the reaction. Thereby, the photocurable composition which can prevent erroneous view of the cured state by color change is obtained. Next, the components constituting the photocurable composition will be described.

The photocurable composition of the present invention has a composition comprising at least one acrylic compound of at least one of an acrylic monomer, an acrylic oligomer, and an acrylic polymer, a photoradical generator, and a leuco dye, but an acrylic monomer, an acrylic oligomer and an acrylic polymer With respect to, in this specification and claims, "acrylic monomer" has the same meaning as a (meth)acrylic monomer, and is used in the meaning including not only an acrylic acid ester monomer but a methacrylic acid ester monomer. Similarly, "acrylic oligomer" has the same meaning as (meth)acrylic oligomer, includes methacrylic acid ester oligomer in addition to acrylic acid ester oligomer, "acrylic polymer" has the same meaning as (meth)acrylic polymer, and acrylic acid ester polymer In addition to the above, it is used in a sense including methacrylic acid ester polymers. In addition, about any of an acryl monomer, an acryl oligomer, and an acryl polymer, it is a compound provided with a radically polymerizable group, and the thing after radical polymerization reaction is distinguished by describing it as "hardening body". This photocurable composition can be made into a hardening body by photocuring an acryl monomer, an acryl oligomer, and an acryl polymer.

Monofunctional acrylic monomers:

A monofunctional acrylic monomer is a component hardened|cured with a radical photopolymerization initiator, and is a low-viscosity liquid before hardening. When a styrenic thermoplastic elastomer is included in the photocurable composition, the monofunctional acrylic monomer dissolves the styrenic thermoplastic elastomer. The hardening body of a monofunctional acrylic monomer adheres to an electronic element or a board|substrate, and expresses waterproofness etc.

Monofunctional acrylic monomers include monofunctional high-polarity monomers such as monofunctional (meth)acrylamide-based monomers in addition to monofunctional (meth)acrylic acid ester monomers. In addition, more specifically, an aliphatic (meth)acrylic acid ester monomer, an alicyclic (meth)acrylic acid ester monomer, an ether-based (meth)acrylic acid ester monomer, a cyclic ether-based (meth)acrylic acid ester acrylic monomer, an aromatic (meth)acrylic acid ester monomers, heterocyclic (meth)acrylic acid ester monomers, etc., and further, hydroxyl group-containing (meth)acrylic acid ester monomer, carboxyl group-containing (meth)acrylic acid ester monomer, acrylamide-based monomer, tertiary amino group-containing (meth)acrylic acid (meth)acrylic acid ester monomers having a polar group such as an ester monomer, an imide-based (meth)acrylic acid ester monomer, a glycidyl group-containing (meth)acrylic acid ester monomer, and a phosphoric acid group-containing (meth)acrylic acid ester monomer.

Specifically, as a monofunctional aliphatic (meth)acrylic acid ester monomer, butyl acrylate, lauryl acrylate, stearyl acrylate, isostearyl acrylate, decyl acrylate, isodecyl acrylate, isononyl acrylate, n- and aliphatic hydrocarbon-based (meth)acrylic acid ester monomers such as octyl acrylate. Since lauryl acrylate is very excellent in the solubility of a styrenic elastomer and it is excellent also in flexibility, when using it together with a styrenic elastomer, it is preferable.

By blending the monofunctional aliphatic (meth)acrylic acid ester monomer, it is dissolved when blending the styrenic thermoplastic elastomer, and the flexibility of the cured product obtained after curing of the photocurable composition is increased, the Martens hardness and Young's modulus are lowered, and the elongation at cut is can be greatly improved.

Specific examples of the monofunctional alicyclic (meth)acrylic acid ester monomer include isobornyl acrylate, cyclohexyl acrylate, dicyclopentanyl acrylate, dicyclopentenyloxyethyl acrylate, and 3,3,5-trimethylcyclohexyl. acrylate, 4-tert-butylcyclohexyl acrylate, and the like.

By mix|blending a monofunctional alicyclic (meth)acrylic acid ester monomer, when a styrenic thermoplastic elastomer is contained, this can be melt|dissolved. The monofunctional alicyclic (meth)acrylic acid ester monomer enhances the adhesive force of the cured product (eg, sealing material) after curing of the photocurable composition, and the adhesive remains when the cured product is peeled from the adherend. can do less In addition, there is an effect of increasing the Young's modulus by making the hardening body tough. In addition, when the ratio of this component is increased, moisture resistance and transparency can be improved.

For the monofunctional aliphatic (meth)acrylic acid ester monomer and the alicyclic (meth)acrylic acid ester monomer, it is preferable to use an acrylic acid ester monomer, respectively. It is because an acrylic acid ester monomer is excellent in photocurability in many cases compared with a methacrylic acid ester monomer, and not only can harden|cure with a comparatively low integrated light quantity, but it is because there exists a tendency for a hardening body to become flexible.

When a monofunctional aliphatic (meth)acrylic acid ester monomer and a monofunctional alicyclic (meth)acrylic acid ester monomer are used, since the adhesive force derived from these components is provided, it can be used as an adhesive agent. Moreover, since it can closely_contact|adhere to a to-be-adhered object and can prevent the penetration|invasion of a foreign material or moisture, it is preferable also as a sealing material.

Moreover, it is preferable to use together an alicyclic (meth)acrylic acid ester monomer and an aliphatic (meth)acrylic acid ester monomer. The aliphatic (meth)acrylic acid ester monomer can increase the flexibility of the cured product and greatly improve the elongation when cutting, while the alicyclic (meth)acrylic acid ester monomer makes the cured product tough to increase the tensile strength. Thereby, by using both of these together, suitable softness|flexibility and hardness can be compatible.

Examples of the ether-based (meth)acrylic acid ester monomer include 2-butoxyethyl acrylate, ethoxydiethylene glycol acrylate, phenoxyethyl acrylate, phenoxydiethylene glycol acrylate, and nonylphenol ethylene oxide-modified acrylate. there is.

As the cyclic ether-based acrylic acid ester monomer, tetrahydrofurfuryl acrylate, (2-methyl-2-ethyl-1,3-dioxolan-4-yl)methyl acrylate, (3-ethyl-3-oxetanyl) methyl acrylate and the like.

Examples of the aromatic acrylic acid ester monomer include phenoxyethyl acrylate, phenoxydiethylene glycol acrylate, 2-hydroxy-3-phenoxypropyl acrylate, nonylphenol ethylene oxide-modified acrylate, and benzyl acrylate. .

Examples of the hydroxyl group-containing acrylic acid ester monomer include 1,4-cyclohexanedimethanol monoacrylate, 2-hydroxybutyl acrylate, 2-hydroxypropyl acrylate, and 2-hydroxyethyl acrylate.

Examples of the carboxyl group-containing acrylic acid ester monomer include ω-carboxy-polycaprolactone monoacrylate, monohydroxyethyl phthalate, 2-acryloyloxyethyl succinic acid, and 2-acryloyloxyethylhexahydrophthalic acid. there is.

Examples of the acrylamide-based monomer include acrylamide, N,N-dimethylacrylamide, N,N-diethylacrylamide, hydroxyethylacrylamide, and acryloylmorpholine.

Examples of the tertiary amino group-containing (meth)acrylic acid ester monomer include 2-(dimethylamino)ethyl methacrylate (DMAEMA).

As an imide type (meth)acrylic acid ester monomer, N-acryloyloxyethyl hexahydrophthalimide, N-acryloyloxyethyl tetrahydrophthalimide, etc. are mentioned.

Examples of the glycidyl group-containing (meth)acrylic acid ester monomer include glycidyl acrylate, glycidyl methacrylate, and 4-hydroxybutyl acrylate glycidyl ether.

Examples of the phosphoric acid group-containing (meth)acrylic acid ester monomer include 2-methcroyloxyethyl acid phosphate.

Among them, from the viewpoint of obtaining a photocurable composition having little adverse effect on color tone change and excellent discrimination of color change due to curing, aliphatic acrylic acid ester monomers, alicyclic acrylic acid ester monomers, aromatic acrylic acid ester monomers, and acrylamide type Monomers are preferred.

In addition, from the viewpoint of improving the storage stability of the photocurable composition and adhesion to the resin, it is preferable to use a monofunctional high-polarity monomer, and among monofunctional high-polarity monomers, an acrylamide-based monomer and a tertiary amino group-containing (meth)acrylic acid Nitrogen-containing monomers, such as an ester monomer and an imide type (meth)acrylic acid ester monomer, are preferable. From a viewpoint of especially improving the adhesiveness to a polyimide film, an imide type (meth)acrylic acid ester monomer is preferable. Moreover, from a viewpoint of improving the adhesiveness to a metal, a phosphoric acid group containing (meth)acrylic acid ester monomer, a hydroxyl group containing acrylic acid ester monomer, and a carboxyl group containing acrylic acid ester monomer are preferable.

When both an alicyclic (meth)acrylic acid ester monomer and an aliphatic (meth)acrylic acid ester monomer are included, the mass ratio of the alicyclic (meth)acrylic acid ester monomer to the aliphatic (meth)acrylic acid ester monomer is 4:1 to It is preferably 1:4. By using both an alicyclic (meth)acrylic acid ester monomer and an aliphatic (meth)acrylic acid ester monomer, the adverse effect to the color tone change of a composition can be decreased, and metal adhesiveness can be improved.

When the monofunctional aliphatic (meth) acrylic acid ester monomer exceeds 4 times by mass of the alicyclic (meth) acrylic acid ester monomer, there is a risk that glue may occur when peeling the cured product of the photocurable composition, adhesive strength, moisture resistance There is a fear that this becomes insufficient. Conversely, in the case of less than 1/4, the cured body tends to solidify, and adhesiveness increases more than necessary due to changes over time, and there is a fear that peeling becomes difficult. And, when the mass ratio of the alicyclic (meth)acrylic acid ester monomer to the aliphatic (meth)acrylic acid ester monomer is in the range of 3:2 to 1:4, a cured product with appropriate adhesion, high elongation when cut, and easy to peel ( For example, a sealing material) can be obtained.

Polyfunctional Acrylic Monomers:

A polyfunctional acrylic monomer is also a component hardened|cured by a radical photopolymerization initiator. When the cured product of the photocurable composition is used as a gasket, sealing material, or sealing material, it can be blended in a small amount for the purpose of adjusting hardness or reducing surface viscosity, but it is difficult to use only this as an essential component, It can be added as an auxiliary component of the functional acrylic monomer. As such a polyfunctional acrylic monomer, a polyfunctional aliphatic (meth)acrylic acid ester monomer, a polyfunctional highly polar monomer, a cyclization polymerizable (meth)acrylic monomer, etc. are mentioned.

As said polyfunctional aliphatic (meth)acrylic acid ester monomer, a bifunctional aliphatic (meth)acrylic acid ester monomer is mentioned, As a specific example of a bifunctional aliphatic (meth)acrylic acid ester monomer, ethylene glycol di(meth)acrylate, diethylene Glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, polypropylene glycol di (meth) acrylate, glycerin di (meth) acrylate, tricyclodecane dimethanol Di (meth) acrylate, neopentyl glycol di (meth) acrylate, 3-methyl-1,5-pentanediol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, 1,9 - Nonanediol di(meth)acrylate, 1, 10-decanediol di(meth)acrylate, etc. are mentioned. When adding a styrenic thermoplastic elastomer, it is preferable to use a difunctional aliphatic hydrocarbon-based di(meth)acrylic acid ester monomer having reactive groups at both terminals because the compatibility with the soft segment is relatively high. Do.

The polyfunctional and highly polar monomers include (meth)acrylic acid ester monomers and bismaleimides having a polar group. Specific examples of the (meth)acrylic acid ester monomer having a polar group include ethoxylated isocyanuric acid di/tri(meth)acrylate, ε-caprolactone-modified tris-(2-acryloxyethyl)isocyanurate, 2- Methacryloyloxyethyl acid phosphate, 2-hydroxy-3-acryloyloxypropyl methacrylate, pentaerythritol diacrylate, pentaerythritol triacrylate, bisphenol A diglycidyl ether acrylic acid adduct, etc. can be exemplified. From a viewpoint of an adhesive improvement, a tris (2-hydroxyethyl) isocyanurate type (meth)acrylic acid ester monomer is preferable.

Further, specific examples of the bismaleimide include 4,4'-diphenylmethanebismaleimide, 4-methyl-1,3-phenylenebismaleimide, and 2,2-bis[4-(4-maleimidephenoxy). Cy)phenyl]propane, bis(3-ethyl-5-methyl-4-maleimidephenyl)methane, 1,6-bis(maleimide)hexane, 1,6'-bismaleimide-(2,2,4 -trimethyl)hexane is exemplified. Among these, since compatibility and photocurability of the photocurable composition are hardly inhibited, 1,6-bis(maleimide)hexane, 1,6'-bismaleimide-(2,2,4-trimethyl)hexane, etc. Aliphatic bismaleimides are preferred.

Alternatively, examples of the cyclization polymerizable (meth)acryl monomer include α-allyloxymethyl acrylate (AOMA) and a dimer of α-hydroxymethyl acrylate (RHMA-D). Since these are low-viscosity, they can be used for adjusting the viscosity of the photocurable composition, and since the three-dimensional crosslinking density is not increased excessively by curing, hardness, heat resistance, and toughness can be improved while maintaining appropriate flexibility. Among the above, α-allyloxymethyl acrylate is preferable from the viewpoint of improving coating properties, improving heat resistance, and improving adhesion to glass.

When the cured product of the photocurable composition is used as a gasket, sealing material or sealing material and the like and a bifunctional or higher functional acrylic monomer is blended, it is preferably contained so as to be 5% by mass or less in the photocurable composition or the cured product thereof, and 1 mass % or less is more preferable. This is because, when it is added in a large amount, there is a concern for an increase in hardness and a decrease in the adhesion to an adherend.

Acrylic oligomers:

An acryl oligomer is a compound which has a (meth)acryl group mainly in the range of 1000-50,000 weight average molecular weights. The acrylic oligomer includes an oligomer obtained by polymerizing the acrylic monomer until it reaches a predetermined molecular weight, and an oligomer having a (meth)acryl group at the terminal or side chain of a main chain other than acryl. For example, polybutadiene acrylic oligomer, acrylamide oligomer, polyisoprene acrylic oligomer, polyurethane acrylic oligomer, polyester acrylic oligomer, polyether acrylic oligomer, epoxy ester acrylic oligomer, bisphenol acrylic oligomer, or and novolac-type acrylic oligomers.

Acrylic Polymer:

The acrylic polymer is a compound having a (meth)acrylic group having a weight average molecular weight of 50,000 to 5,000,000. The acrylic polymer includes a polymer obtained by polymerizing the acrylic monomer or acrylic oligomer to a predetermined molecular weight, and a polymer obtained by adding a (meth)acrylic group to a compound other than the acrylic compound. For example, as the former, there is a homopolymer obtained by polymerizing butyl acrylate. Examples of the latter include compounds in which a (meth)acrylic group is added to a compound having a polybutadiene, acrylamide, polyisoprene, polyurethane, polyester, polyether, epoxy skeleton, etc., and specifically, a polybutadiene-based acrylic polymer , acrylamide-based acrylic polymer, polyisoprene-based acrylic polymer, polyurethane-based acrylic polymer, polyester-based acrylic polymer, polyether-based acrylic polymer, epoxy ester-based acrylic polymer, bisphenol-based acrylic polymer, or novolac-type acrylic polymer can be heard

It is preferable that the compounding quantity of the total of an acryl monomer, an acryl oligomer, and an acrylic polymer is 50 mass % - 99 mass % with respect to the mass of a photocurable composition. Moreover, it is preferable that the compounding quantity of the said monofunctional acrylic monomer is 10 mass % - 94 mass % with respect to the total mass of an acryl monomer, an acryl oligomer, an acrylic polymer, and the thermoplastic elastomer mentioned later.

Styrenic Thermoplastic Elastomers:

A styrenic thermoplastic elastomer (also referred to as a styrenic elastomer) is not an essential component. However, the styrenic elastomer can be dissolved in an acrylic monomer or an acrylic oligomer in the photocurable composition, and transparency may be reduced due to the hard segment thereof. For this reason, the change of color can be visually recognized more easily than when a photocurable composition is transparent. In addition, the styrene-based elastomer can provide rubber elasticity (flexibility) while increasing the mechanical strength of the cured product after curing of the acrylic monomer or acrylic oligomer. And compression permanent distortion can be made small, and a water vapor transmission rate can be made low.

Specific examples of the styrene-based elastomer include styrene-butadiene-styrene block copolymer (SBS), styrene-isoprene-styrene block copolymer (SIS), styrene-ethylene-butylene-styrene block copolymer (SEBS), styrene-ethylene- propylene-styrene block copolymer (SEPS), styrene-isobutylene-styrene block copolymer (SIBS), styrene-ethylene-ethylene-propylene-styrene block copolymer (SEEPS), and epoxy-modified styrene-based elastomers and modified substances.

Among the styrene-based elastomers, unsaturated bonds are formed in soft segments such as styrene-butadiene-styrene block copolymer (SBS), styrene-isoprene-styrene block copolymer (SIS), and styrene-butadiene/isoprene copolymer-styrene block copolymer. Compared with the case where the styrenic elastomer which does not have an unsaturated bond is used for a soft segment, the styrene-type elastomer can make small the compression set distortion of the hardened|cured material. Thereby, when using a hardening body as a gasket, a sealing material, a sealing material, etc., sealing property can be maintained for a long period of time. Moreover, the viscosity of the surface of a hardening body can be reduced and when an inorganic powder is added, it can make it difficult to worsen compression set distortion.

Further, among the styrene-based elastomers, when an epoxy-modified styrene-based elastomer or a styrenic elastomer having an unsaturated bond in the soft segment is used, the epoxy-modified styrene-based elastomer or a styrenic elastomer having an unsaturated bond in the soft segment is not included Compared with , the compression set of the cured product obtained after curing can be reduced, and the sealability in long-term use is improved. In addition, by including the epoxy-modified styrenic elastomer or the styrenic elastomer having an unsaturated bond in the soft segment, the surface viscosity of the cured body can be reduced, and even if inorganic powder is added, permanent compression distortion can be made difficult to deteriorate.

Moreover, it is preferable that the said styrene-type elastomer contains a high molecular weight styrene-type elastomer. Here, the high molecular weight styrene-based elastomer refers to 200,000 or more in terms of weight average molecular weight. It is preferable that it is 250,000 or more, and, as for the weight average molecular weight of this high molecular weight styrene-type elastomer, it is more preferable that it is 400,000 or more. Although there is no upper limit in particular, it can be set as 1 million or less, for example. The weight average molecular weight can be measured using a GPC method (Gel Permeation Chromatography; gel permeation chromatography) and based on a calibration curve (calibration curve) measured with standard polystyrene.

By including the high molecular weight styrenic elastomer, as compared with the case of using a low molecular weight styrenic elastomer having a weight average molecular weight of less than 200,000, permanent compression distortion can be reduced, and when the cured product is used as a gasket, sealing material or sealing material The sealing property can be maintained for a long time. In addition, since the plasticizer can be suppressed from bleeding out by including the high molecular weight styrene-based elastomer, it is possible to obtain a cured product having high flexibility by adding a large amount of the plasticizer.

It is preferable that it is 1-60 mass % in the photocurable composition, and, as for the addition amount in the case of mix|blending a styrenic elastomer, it is more preferable that it is 2-45 mass %. When the mixing|blending of a styrenic elastomer is less than 1 mass %, there exists a possibility that mechanical strength may become low when using the hardening body as a gasket, a sealing material, a sealing material, etc. On the other hand, when it exceeds 60 mass %, there exists a tendency for the viscosity of a photocurable composition to become high easily. If it is 35 mass % or less, fluidity|liquidity is preferable and it is easy to apply|coat.

However, it is preferable that it is 1-7 mass % in the photocurable composition, and, as for the addition amount in the case of a high molecular weight styrene-type elastomer, it is more preferable that it is 2-5 mass %. When the mixing|blending of a high molecular weight styrene-type elastomer is less than 1 mass %, there exists a possibility that mechanical strength may become low. On the other hand, when it exceeds 10 mass %, there exists a tendency for the viscosity of a photocurable composition to become high easily.

Among the high molecular weight styrenic elastomers, it is preferable to use a high molecular weight styrenic elastomer having a predetermined branched chain (typically a branched chain extending radially from a core) called a star polymer. Compared with a straight-chain high molecular weight styrenic elastomer, the high molecular weight styrenic elastomer having such a predetermined branched chain can suppress entanglement of main chains, and the viscosity of the photocurable composition is increased even when blended at a relatively high concentration. can be suppressed. Specifically, this high molecular weight styrenic elastomer can be blended in the photocurable composition at a concentration of about 5 to 20 mass%.

Photoradical Generators:

An optical radical generating agent produces a radical and hardens an acryl monomer, an acryl oligomer, and an acryl polymer by a radical photopolymerization reaction. The photo-radical generator includes a photo-radical polymerization initiator.

Examples of the radical photopolymerization initiator include photopolymerization initiators such as benzophenone-based, thioxanthone-based, acetophenone-based, acylphosphine-based, oxime ester-based, alkylphenone-based and intramolecular hydrogen extraction initiators. Among these, it is preferable to use an alkylphenone-type initiator or an oxime ester-type initiator from a viewpoint especially easy to raise a chromaticity difference.

Examples of the alkylphenone type include 2,2-dimethoxy-2-phenylacetophenone, 1-hydroxycyclohexylphenyl ketone, 2-hydroxy-2-methyl-methylpropanone, 1-[4-(2-hydroxyl) Ethoxy)-phenyl]-2-hydroxy-methylpropanone, 2-hydroxy-1-(4-(4-(2-hydroxy-2-methylpropionyl)benzyl)phenyl)-2-methylpropane -1-one, 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropan-1-one, 2-benzyl-2-(dimethylamino)-4′-morpholinobutyl phenone, 2-dimethylamino-2-(4-methyl-benzyl)-1-(4-morpholin-4-yl-phenyl)-butan-1-one and the like.

Examples of the acylphosphine type (acyl phosphine oxide type) include 2,4,6-trimethylbenzoyl-diphenylphosphine oxide and bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide.

Examples of the intramolecular hydrogen extraction type include methyl benzoylformate, a mixture of oxyphenylacetic acid-2-2-oxo-2-phenylacetoxyethoxyethyl ester and oxyphenylacetic acid-2-2-hydroxyethoxyethyl ester. can be heard

As an oxime ester type (oxyphenylacetic acid ester type), 1-[4-(phenylthio)phenyl]octane-1,2-dione =2-(O-benzoyloxymu), 1-[9-ethyl-6- (2-methylbenzoyl)-9H-carbazol-3-yl]ethanone-1-(O-acetoxime) and the like.

0.1-10 mass parts is preferable with respect to 100 mass parts of total amounts of all the acryl monomers and acryl oligomer including monofunctional and bifunctional or more, and, as for the addition amount of a radical photopolymerization initiator, 1-8 mass parts is more preferable. This is because, when the amount is less than 0.1 parts by mass, polymerization is insufficient and curing may not be completed.

leuco dyes:

The leuco dye is a compound that generally develops color upon contact with an acid, and in the present invention, it functions to confirm the completion of curing of the photocurable composition by developing color after curing of the photocurable composition. Specific examples of the leuco dye include indolyl phthalides, diphenylmethane phthalides, monovinyl phthalides, divinyl phthalides, diphenyl methane aza phthalides, and phthalides including phenyl indolyl aza phthalides. Drews, fluorans, thiazines, styrinoquinolines, lactones, lactams, triphenylmethanes and the like can be mentioned.

Examples of the phthalides include 3,3bis[4-(dimethylamino)phenyl]phthalide, 3,3-bis(p-dimethylaminophenyl)-6-dimethylaminophthalide, and 3-(4-diethylamino). Phenyl)-3-(1-ethyl-2-methylindol-3-yl)phthalide, 3-(4-diethylamino-2-ethoxyphenyl)-4-azaphthalide, 3,3-bis( 1-butyl-2-methyl-1H-indol-3-yl)phthalide and the like.

As fluoranes, 2'-methyl-6'-(N-p-tolyl-Nethylamino)spiro[isobenzofuran-1(3H),9'-[9H]xanthene]-3-one, 1,3 -Dimethyl-6-diethylaminofluoran, 2-chloro-3-methyl-6-dimethylaminofluoran, 3-dibutylamino-6-methyl-7-anilinofluoran, 3-diethylamino-6 -Methyl-7-anilinofluoran, 3-diethylamino-6-methyl-7-xylidinofluoran, 2-(2-chloroanilino)-6-dibutylaminofluoran, 3,6- Dimethoxyfluoran, 3,6-di-n-butoxyfluoran, 1,2-Benz-6-diethylaminofluoran, 1,2-Benz-6-dibutylaminofluoran, 1,2- Benz-6-ethylisoamylaminofluoran, 2-methyl-6-(N-p-tolyl-N-ethylamino)fluoran, 2-(N-phenyl-N-methylamino)-6-(N-p-tolyl) -N-ethylamino)fluoran, 2-(3'-trifluoromethylanilino)-6-diethylaminofluoran, 3-chloro-6-cyclohexylaminofluoran, 2-methyl-6-cyclo Hexylaminofluoran, 3-di(n-butyl)amino-6-methoxy-7-anilinofluoran, 3,6-bis(diphenylamino)fluoran, methyl-3',6'-bisdi phenylaminofluoran, chloro-3',6'-bisdiphenylaminofluoran, and the like can be exemplified.

As thiazines, benzoylo comethylene blue etc. are mentioned.

Examples of the lactams include rhodamine-B-anilinolactam, rhodamine-(p-nitroanilino)lactam, rhodamine-(o-chloroanilino)lactam, rhodamine-(o-nitroanilino)lactam, and the like. can be exemplified.

Examples of triphenylmethanes include leucocrystal violet (LCV).

Further, examples of the lactones include crystal violet lactone (CVL), which is a lactone derivative of crystal violet, and a diazarodamine lactone derivative.

Among these, various lactones, phthalides, and fluoranes having a lactone ring structure are preferable from the viewpoint of being less likely to change color tone after curing and excellent in distinguishing the presence or absence of curing even after a predetermined period of time has elapsed.

The addition amount of leuco dye can be 0.001-2 mass parts with respect to 100 mass parts of an acryl monomer, an acryl oligomer, and an acrylic polymer, and it is preferable that it is 0.005-1 mass part. When it is set as 0.001-0.1 mass part, when hardening|curing to a thickness of 0.5 mm or more, the discrimination of the presence or absence of hardening can be improved. Moreover, when it sets it as 0.1-2 mass parts, the mechanical property of the hardening body of a photocurable composition can be improved. It is considered that the effect of increasing the mechanical properties is observed in a slightly high concentration region as the amount of the leuco dye to be added because the leuco dye promotes a radical reaction.

Plasticizer:

It is preferable to add a plasticizer to the photocurable composition as needed. By adding a plasticizer, high flexibility can be provided to a hardening body, and when used as a gasket or a sealing material, it is preferable. As a plasticizer, when adding a styrenic elastomer, it is preferable to be compatible with the soft segment. Specific examples of the plasticizer include paraffinic oil, olefinic oil, naphthenic oil, and ester plasticizer. Specific examples of the ester plasticizer include phthalic acid ester, adipic acid ester, trimellitic acid ester, polyester, and phosphoric acid ester. , citric acid esters, epoxidized vegetable oils, sebacic acid esters, azelaic acid esters, maleic acid esters, benzoic acid esters, and the like. In addition, in the case of adding the styrenic elastomer, paraffinic oil is preferable among them, and when paraffinic oil is used, the effect of improving the extensibility by physical crosslinking of the hard segment of the styrenic elastomer is small, and the reduction of the effect of the cured product is small. It contributes to the improvement of flexibility and improvement of compression set.

It is preferable that a plasticizer is 30 mass parts or less with respect to 100 mass parts of an acryl monomer and an acryl oligomer. When it exceeds 30 mass parts, the possibility that a plasticizer bleeds out from a hardening body will increase.

Thixotropic agents:

It is preferable to add a thixotropic agent to the photocurable composition. By improving thixotropy, the shape retentivity of the apply|coated photocurable composition improves. Therefore, liquid sagging at the time of application|coating of a photocurable composition can be suppressed, and shape retentivity of the apply|coated photocurable composition can be improved. For example, when the photocurable composition is formed in a three-dimensional object using a dispenser, the photocurable composition can be cured in a coated shape, which is preferable when the cured product is used as a gasket material or an encapsulant.

Specific examples of the thixotropic agent include inorganic thixotropic agents made of inorganic powders such as silica, aluminum oxide and titanium oxide; Although organic thixotropic agents, such as hydrogenated castor oil, amide wax, and carboxymethyl cellulose, etc. are mentioned, Inorganic powder is preferable, Especially, silica is preferable. The reason is that the hydrogen ion index (pH) of the photocurable composition can be easily controlled by subjecting the inorganic powder to a predetermined surface treatment, and among the inorganic powders, silica is easily obtained with such a surface treatment. As for the addition amount in the case of using silica, 2-10 mass parts is preferable with respect to 100 mass parts of an acryl monomer, an acryl oligomer, and an acrylic polymer (including a plasticizer when a plasticizer is included). When it is less than 2 parts by mass, the effect of the addition is difficult to be obtained, and when it exceeds 10 parts by mass, there is a fear that the viscosity of the photocurable composition increases too much or the hardness of the cured body becomes too hard.

As the inorganic powder subjected to the surface treatment, it is preferable to use the inorganic powder having a hydrogen ion index of 3.0 to 11.0. If it is within the above range, since the leuco dye undergoes a predetermined color change by curing, it is excellent in distinguishing the presence or absence of curing. Moreover, as for a hydrogen ion index, it is more preferable that it is 3.6-5.5. This is because the discrimination of the presence or absence of hardening increases. In addition, the said hydrogen ion index is a hydrogen ion index measured with respect to the dispersion liquid which disperse|distributed the inorganic powder used as the density|concentration of 4 mass % in pure water.

coloring agent:

In order to make the color change more vivid, a white inorganic filler may be added to the photocurable composition. By using a white inorganic filler, a small color change can be made more vivid and the discrimination by visual observation is improved. Moreover, when the photocurable composition is apply|coated to the application|coating object with small brightness, the discrimination of the presence or absence of hardening improves.

Specific examples of the colorant include inorganic compounds such as aluminum oxide, titanium oxide, magnesium oxide, calcium carbonate, talc, bentonite, and montmorillonite. Among these, aluminum oxide not only improves the discrimination of the presence or absence of hardening, but since it also has the effect of improving applicability|paintability by providing thixotropy suitably, it is especially preferable.

Moreover, it is preferable that it is 3.0-11.0, and, as for the hydrogen ion index of a colorant, it is more preferable that it is 3.6-5.5. This is because the effect of imparting thixotropy similar to that of adding the thixotropy imparting agent is obtained within this range, and a synergistic effect of imparting thixotropy can be expected.

Other Ingredients:

The photocurable composition can mix|blend various additives suitably in the range which does not deviate from the meaning of this invention. In addition to the plasticizer and thixotropy imparting agent, for example, a silane coupling agent, a polymerization inhibitor, an antifoaming agent, a light stabilizer, an antioxidant, an antistatic agent, a thermally conductive filler, other functional fillers, etc. there is.

It is preferable to set it as 10-1000 Pa.s at 25 degreeC, and, as for the viscosity of a photocurable composition, it is more preferable to set it as 20-300 Pa.s. If it is less than 10 Pa·s, liquid sagging tends to occur when applying with a dispenser to an electronic device or the like. On the other hand, when it exceeds 1000 Pa·s, application with a dispenser becomes difficult. Moreover, when it is set to 20 Pa·s or more, the shape retentivity between application and curing is improved, and when it is set to 200 Pa·s or less, high-precision dispensing using a thinner needle becomes possible. In addition, the said viscosity can be made into the value measured using a B-type rotational viscometer at a rotation speed of 10 rpm and a measurement temperature of 25 degreeC.

Moreover, it is preferable to set it as 2 or more at 25 degreeC, and, as for the thix ratio of a photocurable composition, it is more preferable to set it as 4 or more. When the thixotropic ratio is 2 or more, it is possible to suppress spreading of the photocurable composition before curing when the photocurable composition is applied. In addition, by setting the thix ratio to be 4 or more, the spread can be reduced even with a photocurable composition having a particularly low viscosity, and a highly precise shape using a thinner needle can be formed. The thix ratio is a value calculated as a ratio (viscosity (1 rpm)/viscosity (10 rpm)) by measuring the viscosity at a rotation speed of 1 rpm and 10 rpm at a measurement temperature of 25° C. using a B-type rotational viscometer. In addition, although the upper limit of thix ratio is not limited, It is preferable to set it as about 20 or less.

Cured body of photocurable composition:

A photocurable composition can be hardened by photocuring reaction, and can be used for various uses, such as an adhesive agent, a masking material, a gasket, a sealing material, and a sealing material. For example, after applying a photocurable composition to an electronic device installed on an electronic substrate or a metal exposed portion to cover an adherend, the photocurable composition is photocured by ultraviolet irradiation and used to obtain a sealing material. In addition to ultraviolet light, as an active energy ray, an energy ray that activates a (meth)acryloyl group, such as a visible ray or an electron beam, and an energy ray that generates radicals in a radical photopolymerization initiator can be used. The light source for irradiating ultraviolet rays includes, for example, a high-pressure mercury lamp, a metal halide lamp, or an ultraviolet LED.

As the sealing material, from the viewpoint of imparting rubber elasticity, the hardness is preferably 60 degrees or less, more preferably 40 degrees or less, still more preferably 20 degrees or less, as A hardness according to JIS K6253-3:2012. 5 degrees or less is more preferable. If it is 5 degrees or less, it can use as a sealing material by which an extremely low load is calculated|required. Moreover, it is preferable that the compression set of a hardening body is 50 % or less. This is because long-term sealing properties can be secured.

In addition, the cured product of the photocurable composition of the present invention preferably has a Martens hardness measured by a nanoindentation test in the range of 0.005 to 30 N/mm ² . When the Martens hardness is within this range, it has predetermined flexibility and flexibility, and is suitable for use in sealing materials such as gaskets, masking materials and protective materials such as sealing materials, adhesives, and vibration-proof materials. The measuring method of Martens hardness can be made into the method specifically described in an Example.

As a sealing material, it is preferable to provide the intensity|strength which has the flexibility which can be applied also to a flexible board|substrate, and the repairability which can be removed after using it for the use for sealing an electronic component. In view of such properties as the storage modulus E', it is preferably in the range of 0.4 to 4.1 MPa. By making the storage elastic modulus E' of 0.4 MPa or more, the cured body of the photocurable composition is less likely to break apart and easy to repair. do. Moreover, when giving priority to long-term adhesiveness and protective effect over repairability as a sealing material, it is preferable that the said storage elastic modulus E' becomes the range of 4.1-250 MPa. If it is this range, the hardening body of a photocurable composition becomes difficult to peel from a to-be-adhered body by toughness increasing, and by providing appropriate rigidity, it can suppress that wiring disconnects by bending|flexion.

In addition, as an adhesive or reinforcing member applied to a boundary portion between a rigid substrate and a flexible substrate, the mechanical strength such as Young's modulus and Martens hardness of the cured body of the photocurable composition should be appropriately required for the application. desirable.

The above embodiment is an illustration of the present invention, and changes in the embodiment or addition or combination of known techniques can be made without departing from the spirit of the present invention, and these techniques are also included in the scope of the present invention. .

Example

Next, the present invention will be described in more detail based on Examples (Comparative Examples). The photocurable composition which consists of the composition shown in each following table|surface, and the hardening body which hardened these photocurable compositions were produced, and it was set as Samples 1-Sample 29. And various tests were done about these samples.

[Table 1]

[Table 2]

[Table 3]

[Table 4]

<Production of sample>

Sample 1 to Sample 29:

Acryl monomer, acrylic oligomer, acrylic polymer, leuco dye, and styrenic elastomer required according to the sample are mixed, and after they are sufficiently mixed, an additive and a photo-radical polymerization initiator are mixed to prepare the photocurable compositions of Samples 1 to 29 did. These photocurable compositions were irradiated with ultraviolet rays (LED light source with a wavelength of 365 nm) under the conditions of an illuminance of 250 mW/cm ² and an accumulated light amount of 15000 mJ/cm ² , and cured products of Samples 1 to 29 were obtained.

In the above tables, as the acrylic monomer, lauryl acrylate as the aliphatic acrylate, isobornyl acrylate as the alicyclic acrylate, phenoxyethyl acrylate as the aromatic acrylate, and 2-hydride as the hydroxyl group-containing acrylate oxyethyl acrylate, ω-carboxy-polycaprolactone monoacrylate as the carboxyl group-containing acrylate, 2-methacryloyloxyethyl acid phosphate as the phosphoric acid-containing acrylate, and acryloylmorph as the amide group-containing acrylate For Pauline, 2-(dimethylamino)ethyl methacrylate was used as the amino group-containing acrylate, and 1,9-nonanediol diacrylate was used as the bifunctional aliphatic acrylate, respectively.

In addition, as an acrylic polymer, the acrylic polymer ("RC500 (XX067C)" (brand name), the Kaneka Corporation make) of an acrylic skeleton was used.

As the radical photopolymerization initiator, 2-hydroxy-2-methyl-methylpropanone as an alkylphenone-based initiator, and bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide as an acylphosphine oxide-based initiator, intramolecularly A mixture of oxyphenylacetic acid-2-2-oxo-2-phenylacetoxyethoxyethyl ester and oxyphenylacetic acid-2-2-hydroxyethoxyethyl ester as a hydrogen extraction type, and 1 as an oxyphenylacetic acid ester type -[9-ethyl-6-(2-methylbenzoyl)-9H-carbazol-3-yl]ethanone-1-(O-acetoxime) was used, respectively.

As leuco dyes, as fluoranes, 2'-methyl-6'-(N-p-tolyl-Nethylamino)spiro[isobenzofuran-1(3H), 9'-[9H]xanthene]-3-one ( “RED520” (trade name), manufactured by Fukui Yamada Chemical Industry Co., Ltd., and 3-bis(p-dimethylaminophenyl)-6-dimethylaminophthalide (“Crystal Violet Lactone (Crystal Violet Lactone) CVL)", manufactured by Fukuyamada Chemical Industry Co., Ltd.), and "Leuco Crystal Violet" ((trade name), manufactured by Tokyo Oka Industrial Co., Ltd.) as triphenylmethanes, respectively.

As the styrene-based thermoplastic elastomer, a styrene-isobutylene-styrene triblock copolymer (“SIBSTAR 102T” (trade name), manufactured by Kaneka Corporation) was used.

As an additive, a photo-acid generator ("CPI-210S" (trade name), manufactured by San Apro Co., Ltd.), as a viscosity modifier and thixotropic imparting agent, silica ("Aerosil 200" (trade name), manufactured by Nippon Aerosil Co., Ltd., specific surface area) For this hydrophilic fumed silica of about 200 m ² /g), aluminum oxide (“Alu C” (trade name), manufactured by Nippon Aerosil Co., Ltd., fumed aluminum oxide) was used as a coloring agent, respectively.

<Various tests and evaluations>

Various tests demonstrated below were performed about each said sample, and the characteristic of the photocurable composition and its hardening body was evaluated.

Calculation of curing rate when transitioning from a photocurable composition to a cured body:

When the photocurable composition is in an intermediate state from an uncured state, that is, a state in which the curing rate is 0%, to a fully cured state, that is, a state in which the curing rate is 100%, the curing rate to some extent is It was measured by the FT-IR method whether it is advancing, ie, what % of hardening rate is. The FT-IR method records infrared absorption spectra with absorbance on the vertical axis for the uncured material and the cured product, and the fluctuation peak attributed to the chemical bond that decreases with the curing reaction (820 cm ^-1 to 780 cm ^{-1 )} and the internal standard The area of the peak (1730 cm ^-1 ) was read from each spectrum, and the curing rate of the sample whose curing rate was not determined was calculated based on the values of the uncured product and the cured product.

More specifically, let A be the area of the fluctuation peak of the measured sample, let the area of the internal standard peak be B, and the ratio R=A/B of the area is calculated|required. Here, if the R value of the uncured material is Ru, and the R value of the cured product (cured product produced by irradiating ultraviolet rays under the condition of accumulated light amount of 15000 mJ/cm ² ) is Rc, the reduction ratio Dc (%) of the Rc value to the Ru value ), that is, the reduction rate of the R value of the cured product can be obtained by the following formula (2).

Dc=(1-Rc/Ru)×100… Equation (2)

Next, when the R value is obtained from the infrared absorption spectrum of the sample for which the curing rate is to be determined, the reduction rate D (%) of the R value with respect to the Ru value can be obtained by the following formula (3).

D=(1-R/Ru)×100… Equation (3)

The curing rate C (%) of the sample for which the curing rate is to be determined can be obtained by comparing the D value of the sample with the Dc value. That is, it can be calculated|required by following formula (4).

C=D/Dc×100… Equation (4)

Regarding the determination of the curing rate by FT-IR, “Measurement of curing rate of chemically reactive resins (UV curing, thermosetting, moisture curing) and its practice – practical application of adhesives, encapsulants, paints, etc. (B) by Mikiyoichi)” (Information Agency, Inc.).

Measurement of chromaticity:

Chromaticity was measured as follows. When explaining with reference to the schematic diagram shown in FIG. 1, first, as shown in FIG. 1A, two 1 mm thick transparent glass plates 11 are prepared, and on one side of the one sheet, PET (HSPX) subjected to 0.1 mm peeling treatment is applied. Keep it attached (not shown). A shim ring (spacer) 12 with a thickness of 1 mm having a circular penetration hole 13 with a diameter of 10 mm is disposed on the glass plate 11 on the side to which the PET is not attached, and the other side of the shim ring is placed so that the PET faces the shim ring. A glass plate is placed and the shim ring is sandwiched by two glass plates.

Next, the chromaticity of the white plate for calibration as a reference is measured (measurement of a blank, Fig. 1B). Then, the photocurable composition of each sample is apply|coated in the penetration hole 13 of the shim ring 12, and the chromaticity of the photocurable composition before hardening which entered into the penetration hole is measured as shown in FIG. 1C. At this time, a white plate for correction (not shown) is disposed under the glass plate 11 serving as the lower side. And it is in order not to be influenced by oxygen in the air to enclose a photocurable composition with two glass plates. And, as shown in Fig. 1D, UV lamp (manufactured by Panasonic Co., Ltd., "Aicure UJ30", wavelength 365nm, illuminance 250mW/cm ² ) 16 The photocurable composition 15 is irradiated with ultraviolet rays for a predetermined time. Finally, as shown in Fig. 1E, the chromaticity of the cured product of the photocurable composition was measured with a spectrophotometer (manufactured by Color Techno Systems, Inc., "Handy Spectrophotometer JX777") (14). And the actual measurement of chromaticity calculated|required beforehand the ultraviolet-ray irradiation time at which the curing rate would be 50% for each sample, and calculated|required the chromaticity with the sample after irradiating ultraviolet-ray for that time. The value of Equation (1), which is a chromaticity change parameter, was calculated from the chromaticity of each sample uncured, cured 50%, and cured (cured 100%), and the results are shown in the above tables.

Measurement of chromaticity difference:

First, the same sample as the sample used for the measurement of chromaticity is prepared. Next, the sample is placed on a white plate for calibration, the color tone of each sample is compared with the color of the color chip of the color sample "PANTONE uncoated chips" (manufactured by PANTONE) by visual observation, and the closest color number is recorded. did. Then, the chromaticity of each color chip is measured with the spectrophotometer. The chromaticity difference ΔE was calculated from the chromaticity corresponding to the color of each sample obtained in this way, uncured and after curing (curing rate of 100%), and the results are shown in the above tables.

Separately, the sample used in the measurement of the chromaticity was placed on a white plate for calibration, and the second chromaticity difference ΔE ₂ was obtained from the chromaticity measured with a spectrophotometer for the chromaticity of each sample.

Further, in the present invention, in the case of simply "chromaticity difference ΔE", the chromaticity difference based on the color of the color chip is indicated, and in the latter case, it is expressed as "second chromaticity difference ΔE ₂ ". Here, the above-mentioned chromaticity difference ?E is a value that faithfully reflects the color change seen by visual observation. Therefore, when this chromaticity difference ?E is large and the chromaticity change parameter described above is within a predetermined range, it means that it is easy to distinguish between before curing and after the end of photocuring by visual observation.

On the other hand, for example, in a production process, in a special case of inspecting the cured state using a spectrophotometer or a colorimeter, the second chromaticity difference ΔE ₂ is preferably 10 or more, and more preferably 20 or more. In this case, the chromaticity difference ΔE is changed to the second chromaticity difference ΔE ₂ , and only the second chromaticity difference ΔE ₂ may be 10 or more. Moreover, it is preferable that both of chromaticity difference (DELTA)E and _2nd chromaticity difference (DELTA)E2 are 10 or more, and it is more preferable that it is 20 or more. In this case, in addition to being able to cope with both the inspection by the spectrophotometer and the inspection by visual observation, inadvertent contact with the uncured photocurable composition can be prevented, and the work safety of the workers can be improved. . In addition, although the chromaticity difference ΔE using the color chip selected by visual observation and the chromaticity difference ΔE ₂ by the spectrophotometer had a correlation in most cases, in some samples, the values deviated from the correlation. Although the reason is not clear, it is believed that a difference has occurred between the chromaticity measured on the spectral color side and the chromaticity perceived by visual observation due to a sample in which the reflected color and the transmitted color are opposite to each other, the degree of light diffusivity, or the like.

Calculation of ΔE/chromaticity change parameters:

Each table shows the value obtained by dividing the chromaticity difference ΔE by the chromaticity change parameter. This value becomes a larger value when the chromaticity difference is large and the chromaticity change parameter is small (that is, the chromaticity change in the latter half of the reaction is large). Therefore, it can be expected that this value has a correlation with the discrimination of the state of the coin.

Adequacy of hardening judgment test:

For each of the above samples, each test body before curing (0% curing rate), 25% curing rate, 50% curing rate, 75% curing rate, and after curing (100% curing rate) was prepared for the main test. To the tester, the test body before curing and the test body after curing are first shown for 30 seconds, then these specimens are hidden, and after 3 minutes, the five specimens with different curing states are randomly shown one by one, and the specimen has a curing rate of 100 % or something else. This test was performed with respect to one sample (that is, five test bodies) with respect to 5 people, and the number of people with an incorrect answer was counted. The result is shown in each said table|surface.

Martens hardness (N/mm ² ):

Using a nanoindenter (manufactured by ELIONIX, ENT-2100), the nanoindentation test of the cured body of each sample was performed. The test piece is a glass plate having a thickness of 1 mm, a photocurable composition is applied to a thickness of 200 μm, and using an LED having a wavelength of 365 nm, an illuminance of 250 mW/cm ² , and a cumulative light amount of 15000 mJ/cm ² By irradiating ultraviolet rays under the conditions of 2 . The produced hardening body was used. And with the said nanoindenter, the Martens hardness of the hardening body was measured under the conditions of 0.1 mN of press-in maximum load, and 0.01 mN/sec of press-in speed.

1 Immersion test with hydrochloric acid:

A cured body of each sample was obtained by irradiating ultraviolet rays with an accumulated light amount of 15000 mJ/cm ² to each of the samples and curing them to a thickness of 1 mm. Then, a 0.2 g test piece was cut out from this hardening body, 1N hydrochloric acid was immersed in 10 g, and it left still in 70 degreeC environment for 120 hours. Then, after 120 hours, the test piece was taken out and the surface moisture was lightly wiped off. The test piece obtained in this way was compared with the color chip of the color sample "PANTONE uncoated chips" (manufactured by PANTONE) by visual observation, and the closest color number was recorded. Subsequently, the chromaticity of each color chip is measured with the spectrophotometer, and the chromaticity difference is calculated from the chromaticity of the test piece after the test of each sample and the chromaticity of the test piece before the test, and the chromaticity difference _ΔE3 after the immersion test in each table The results are shown in the items of

<Analysis of test results>

Looking at the results of the test to confirm the adequacy of the curing judgment, for the sample 28 with ΔE of less than 10, the tester incorrectly answers that the curing rate is other than 100 even for the specimen after curing (curing rate 100%), or the curing rate There were some testers who made the mistake of saying that the curing rate was 100% even if it was 75%, so there were many people who gave incorrect answers. This was considered to be due to the fact that the difference between the chromaticity at a curing rate of 100% and the chromaticity before curing was small. In addition, in Sample 29 with a chromaticity change parameter exceeding 2.0, an incorrect answer was found, such as a tester who erroneously stated that the curing rate was 100% even though the curing rate was 25%. This was considered to be due to the fact that a significant chromaticity change occurred throughout the reaction and was difficult to distinguish from the case of the latter half of the reaction and the case of the end of the reaction.

On the other hand, in samples 9, 10, and 18, there was one wrong answer in the adequacy confirmation test of hardening judgment. In Sample 9, although the value of the chromaticity change parameter was small, 0.5 or less, the chromaticity difference ΔE exceeded 10 but was less than 20, so it is considered that the color distinction was somewhat difficult to understand. In Sample 10, the chromaticity difference ΔE was improved compared to Sample 9 and exceeded 20 but less than 30, and the chromaticity change parameter was 2.0 or less but slightly larger than 1.0. It is considered difficult to understand. Sample 18 had a sufficiently large value of chromaticity difference ΔE exceeding 30, but a chromaticity change parameter of 2.0 or less but a large value exceeding 1.0, so it is considered that the color change in the latter half of the reaction was somewhat difficult to understand.

On the other hand, for samples other than Sample 9, Sample 10, Sample 18, Sample 28, and Sample 29, that is, samples 1 to 8, 11 to 17, and 19 to 27, the number of people giving incorrect answers was zero. About these samples, ΔE was 30 or more in any of the samples, and the chromaticity change parameter was in the range of 0 to 1.0.

From these results, if the chromaticity difference ΔE is 10 or more and the chromaticity change parameter is in the range of 0 to 2.0, there is a possibility that there is a possibility that there is a slight error in the suitability confirmation of the curing judgment, but in many cases, the suitability confirmation can be performed accurately, and the chromaticity difference It was found that if ΔE was 30 or more and the chromaticity change parameter was 1.0 or less, it was possible to reliably confirm the suitability of curing judgment without being distorted.

When looking at the value of "ΔE/chromaticity change parameter", it was found that the samples 9, 10, and 18 were in the range of 20 to 40. In addition, for all the samples in which no one gave an incorrect answer, the value of "ΔE/chromaticity change parameter" was a value exceeding 40. Therefore, it turns out that the value of "ΔE/chromaticity change parameter" is preferably 20 or more, and particularly preferably 40 or more.

Comparing Samples 1 to 8, except for Sample 6, since the chromaticity difference ΔE was 30 or more, it was found that the change in chromaticity was particularly large. In addition, since the initial chromaticity value of sample 6 is (31.9, 48.4), it turns out that it is colored red. Since Sample 6 was a phosphoric acid-containing monomer, it is considered that the reason that the photocurable composition became acidic was the reason for the change in the initial chromaticity. Therefore, it turned out that it is preferable to use the acryl monomer which does not have an acidic group from a viewpoint that the color tone of an initial stage is colorless.

Samples 1 to 3 and 7 all had a second chromaticity difference of 20 or more. Accordingly, it was found that when each monomer of aliphatic, alicyclic, aromatic, and acrylamide was used, not only visual identification but also spectrophotometric identification improved.

Sample 7 had somewhat larger Martens hardness compared to Samples 1 to 6. It is presumed that the acrylamide-based monomer promotes the curing reaction. Therefore, it has been found that it is preferable to use an acryl monomer excluding an acrylamide-based monomer when flexibility is required, and to add an acrylamide-based monomer when rigidity is required by increasing hardness.

Comparing Samples 2 and 9 to 11, the acylphosphine-based initiator and Samples 9 and 10, which are the intramolecular hydrogen extraction initiators, had slightly smaller values of ΔE. This is considered to be because these samples had a slightly yellowish chromaticity in the initial stage, and were somewhat closer to the color after curing. Therefore, it turned out that it is preferable to use an alkylphenone type initiator or an oxime ester type initiator as a radical polymerization initiator.

Comparing the magnitude of the addition amount of the leuco dye in Samples 13 to 15, the chromaticity difference tends to decrease as the amount of the leuco dye added decreases. The reason the chromaticity difference became small is considered to be because the density|concentration of dye became low. By the way, in Sample 12 in which the addition amount of leuco dye exceeded 1 mass part, although the chromaticity difference (DELTA)E exceeded 30, it became a value smaller than Sample 15 which is 0.001 mass part. The reason is considered to be that, when the addition amount of the leuco dye is larger than the predetermined amount, the initial chromaticity becomes somewhat yellowish and approaches the color after curing. Therefore, it turned out that the addition amount of leuco dye is preferable in it being the range of 0.005-1 mass part. In addition, sample 12 has the largest second chromaticity difference ΔE ₂ among them. Therefore, it turned out that the direction of the addition amount exceeding 1 mass part is preferable when hardening is judged by a spectrophotometer.

Comparing Sample 2 and Samples 19 to 23, as compared to Sample 2 without the coloring agent, Samples 19 to 23 containing the colorant had a chromaticity change parameter of more than 0.1, whereas the chromaticity change parameter of Sample 2 was greater than 0.1. is 0.1 or less. Therefore, it turned out that the visibility of color tone becomes high by including the aluminum oxide which is white powder as a coloring agent.

In addition, since the second chromaticity difference ΔE ₂ was particularly large in samples 19, 20, 21, and 22, in order to improve the discrimination by spectrophotometry, the amount of the colorant added relative to the total amount of the resin component (100 parts by mass), It turned out that it is preferable that it is 0.1-1.5 mass parts.

In addition, in Sample 22 and Sample 23, the initial color tone was red. This is considered to be because the pH of the silica used in the present invention is 4.0-4.5 and the pH of aluminum oxide is 4.5-5.5, and the acidity of the photocurable composition is increased by adding a large amount. Therefore, it turned out that it is preferable that the addition amount of such an additive is about 5 mass parts or less with respect to 100 mass parts of total amounts of a resin component.

As a result of the immersion test with 1N hydrochloric acid, the chromaticity difference between Sample 28 and Sample 29 was less than 20 and a small value, but Samples 1 to 27 all had a chromaticity difference of 20 or more. Therefore, it turned out that it can discriminate|determine that it is a hardening body which can identify a chromaticity change by performing such an immersion test.

11: glass plate
12: shim ring (spacer)
13: through hole
14: spectrophotometer
15: photocurable composition
16: UV lamp

Claims (13)

At least one acrylic compound selected from an acrylic monomer, an acrylic oligomer and an acrylic polymer, a photo radical generator, and a leuco dye,
Uncured color values (L ^* ₀ , a ^* ₀ , b ^* ₀ ) and cured color values (L ^* ₁₀₀ , a ^* ₁₀₀ ) defined in CIE1976 (L ^* , a ^* , b ^* ) color space described in JISZ8781-4 , b ^* ₁₀₀ ) has a chromaticity difference ΔE of 10 or more, and a chromaticity change parameter represented by the following formula (1) is in the range of 0 to 2.0:
[Formula 1]

[In the formula (1), a ^* ₀ and b ^* ₀ represent the chromaticity a ^* value and b ^* value in the L ^* a ^* b ^* color space before curing, and a ^* ₅₀ and b ^* ₅₀ are L * a * b * chromaticity in L ^* a ^* b ^* color space at a rate of 50% represents a ^* value and b ^* value, where a ^* ₁₀₀ and b ^* ₁₀₀ are chromaticity in L ^* a ^* b ^* color space after curing denotes a ^* value and b ^* value]. According to claim 1,
A photocurable composition that does not contain an acid generator. 3. The method of claim 1 or 2,
The photocurable composition, wherein the acrylic compound is at least one of a monofunctional acrylic monomer, a bifunctional or higher functional acrylic oligomer, and a bifunctional or higher functional acrylic polymer. 4. The method according to any one of claims 1 to 3,
The photocurable composition, wherein the acrylic compound contains at least a monofunctional acrylic monomer and further contains a styrenic elastomer. 5. The method of claim 4,
The photocurable composition, wherein the styrenic elastomer is at least one of a high molecular weight styrenic elastomer having a weight average molecular weight of 200,000 or more, an epoxy-modified styrenic elastomer, and a styrenic elastomer having an unsaturated bond in the soft segment. 5. The method of claim 4,
The photocurable composition wherein the styrene-based elastomer is a styrene-isobutylene-styrene block polymer. 7. The method according to any one of claims 1 to 6,
The photocurable composition further comprising an inorganic powder. A cured product obtained by curing the photocurable composition according to any one of claims 1 to 7, wherein ΔE changes by 20 or more when immersed in 1N hydrochloric acid at 70°C for 120 hours. 9. The method of claim 8,
A cured body having a Martens hardness of 0.005 to 50 N/mm ² as measured by a nanoindentation test. The cured product of the photocurable composition according to any one of claims 1 to 7, or the cured product according to any one of claims 8 to 9, wherein the sealing material has a compression set of 50% or less. A protective material comprising the cured product of the photocurable composition according to any one of claims 1 to 7, or the cured product according to any one of claims 8 or 9, which covers an electronic element or wiring on a substrate. case having an opening,
a cover body that closes the opening; and
The sealing material according to claim 9 provided in at least one of the case and the cover body,
A waterproof structure in which the sealing material is compressed and deformed by the fitting of the case and the cover body to seal the opening in a liquid-tight manner. A sealing material comprising at least a step of applying the photocurable composition according to any one of claims 1 to 7 and a step of irradiating an activation energy ray, selected from a sealing material, a protective material, a masking material, an adhesive, and a vibration-proof material A method for producing at least one cured body.

Images