KR20140014550A - Composite sheet, method for preparing the same, flexible substrate comprising the same and display apparatus comprising the same - Google Patents

Abstract

The present invention relates to a composite sheet, a production method of the same, a flexible substrate comprising the same, and a display device comprising the same, more specifically to: a composite sheet which contains a matrix composition containing a UV-curable silicon based resin and an initiator, and a cured product of a reinforcing material impregnated to the matrix composition; a production method of the same; a flexible substrate comprising the same; and a display device comprising the same.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a composite sheet, a method of manufacturing the same, a flexible substrate including the same, and a display device including the flexible sheet.

The present invention relates to a composite sheet, a method of manufacturing the same, a flexible substrate including the composite sheet, and a display device including the composite sheet. More specifically, the present invention is a composite sheet capable of low thermal expansion, good flexibility, heat resistance and transparency, is made by UV curing and has excellent surface properties, and can minimize the decrease in surface roughness, its manufacturing method, including the same The present invention relates to a flexible substrate and an apparatus including the same.

Glass substrates having excellent heat resistance and transparency and low coefficient of linear expansion have been widely used as substrates for liquid crystal display devices, organic EL display devices, color filter substrates, and solar cell substrates. BACKGROUND ART [0002] In recent years, as a substrate material for a display device, miniaturization, thinness, weight reduction, impact resistance, and flexibility are required, and plastic materials are attracting attention as a material for replacing glass substrates.

In recent years, materials such as polyethylene terephthalate (PET), polyethersulfone (PES), polyethylene naphthalate (PEN), polyarylate (PAR), polycarbonate (PC) and polyimide . However, these materials have a problem of causing warpage of the product and disconnection of the wiring due to a high thermal expansion coefficient. The polyimide-based resin has a relatively low thermal expansion coefficient, but it has been pointed out that it is not suitable as a substrate material due to its extremely low transparency, high birefringence, hygroscopicity and the like.

In this regard, Japanese Laid-Open Publication No. 2004-51960 discloses a transparent hybrid optical sheet prepared from an alicyclic epoxy resin containing an ester group, a bisphenol A epoxy resin, an acid anhydride curing agent, a catalyst and a glass fiber cloth, Japanese Unexamined Patent Application, First Publication No. 2005-146258 discloses a transparent hybrid optical sheet prepared from an epoxy resin having an alicyclic epoxy resin containing an ester group and a dicyclopentadiene skeleton, an acid anhydride-based curing agent and a glass fiber cloth, Discloses a transparent substrate made of a bisphenol A type epoxy resin, a bisphenol A novolac type epoxy resin, an acid anhydride type curing agent, and a glass fiber cloth. However, the above patents are disadvantageous in that display performance is deteriorated because stress is generated between the fiber and the resin matrix, breakage occurs thereby, and optical anisotropy is large.

In the case of the glass fiber-resin composite, the surface roughness of the composite is determined by factors such as the low surface properties of the glass fiber and the flow of conformal resins, the shrinkage during curing, and the difference in the coefficient of thermal expansion between the resin and the fiber fabric caused by heat. Degradation occurs.

An object of the present invention is to provide a composite sheet having low thermal expansion and good flexibility, heat resistance and transparency.

Another object of the present invention is to provide a composite sheet having excellent surface properties by applying UV curing.

Still another object of the present invention is to provide a composite sheet capable of minimizing a decrease in surface roughness.

Still another object of the present invention is to provide a composite sheet manufacturing method capable of minimizing a decrease in surface roughness that may occur in a compounding process of a reinforcing material and a decrease in surface roughness due to curing shrinkage that occurs during high temperature curing.

Still another object of the present invention is to provide a method for manufacturing a composite sheet having a short process time in terms of processability.

Still another object of the present invention is to provide a flexible substrate and a display device including the composite sheet.

Composite sheet according to an aspect of the present invention may be composed of a composition for a matrix comprising a UV-curable silicone resin and an initiator, and a cured product of the reinforcing material impregnated in the composition for the matrix.

The composite sheet according to another aspect of the present invention may be composed of a composition for a matrix including a silicone-based resin and a UV curable catalyst, and a cured product of the reinforcing material impregnated in the composition for the matrix.

Composite sheet manufacturing method according to another aspect of the present invention comprises the steps of preparing a composition for a matrix comprising a UV-curable silicone-based resin and an initiator; And impregnating a reinforcing material into the composition and UV curing.

Composite sheet manufacturing method according to another aspect of the present invention comprises the steps of preparing a composition for a matrix comprising a silicone-based resin and a UV curing catalyst; And impregnating a reinforcing material into the composition and UV curing.

Another aspect of the present invention, the flexible substrate and the display device may include the composite sheet.

The present invention provides a composite sheet having low thermal expansion properties, good flexibility, heat resistance and transparency, and having excellent surface properties by applying UV curing and minimizing a decrease in surface roughness. The present invention provides a method of manufacturing a composite sheet which can minimize the decrease in surface roughness that may occur in the composite process of the reinforcing material and the decrease in surface roughness due to the curing shrinkage that occurs during high temperature curing and shorten the process time in terms of processability. . The present invention provides a flexible substrate and a display device including the composite sheet.

Figure 1 shows a cross-sectional view of a composite sheet of an embodiment of the present invention.
10: Composite sheet, 1: Matrix, 2: Fiberglass

The composite sheet of one aspect of the present invention may be composed of a composition for a matrix containing a silicone-based resin and a cured product of a reinforcing material impregnated in the composition for the matrix.

The reinforcement material and the silicone resin have a difference in coefficient of thermal expansion. As a result, the conventional composite sheet manufactured by thermal curing not only lowers the surface roughness that may occur in the compounding process of the reinforcing material, but also has a large decrease in the surface roughness due to curing shrinkage at high temperature curing. On the other hand, the composite sheet of the present invention can minimize the decrease in surface roughness as a UV cured product.

The composite sheet may have a surface roughness Ra of 100 nm or less, preferably 50 nm or less, more preferably 5 nm-50 nm, and the young, s modulus may be 1-200 MPa, preferably 1-150 MPa.

The composite sheet may have a coefficient of thermal expansion of 0 ppm / ° C.-400 ppm / ° C., preferably 0 ppm / ° C.-10 ppm / ° C., more preferably 3 ppm / ° C.-7 ppm / ° C. Within this range, thermal deformation can be suppressed in manufacturing the flexible substrate.

The coefficient of thermal expansion, ASTM E 831, is a method of measuring the dimensional change with temperature using a thermo-mechanical analysizer (expansion mode, force 0.05N), and then from the curve of the sample length with temperature (30 ° C-250 ° C). It can be measured.

The thickness of the composite sheet may be 15 탆 to 200 탆. Within this range, it can be used as a composite sheet for a flexible substrate.

The composite sheet is a matrix; And it may be composed of a reinforcing material contained in the matrix. Figure 1 shows an embodiment of a composite sheet of the present invention. The composite sheet 10 has a structure in which the reinforcing material 2 is contained in the matrix 1. The reinforcement may be included in a dispersed, single layer or multiple layer structure.

Matrix: reinforcing material in the composite sheet may be included in a weight ratio of 70:30 to 95: 5. In the above range, it may have physical properties of the composite sheet that can be used as a flexible substrate. Preferably it may be included in a weight ratio of 80:20 to 90:10.

In one embodiment, the composite sheet may be composed of a matrix composition comprising a UV-curable silicone-based resin and an initiator, and a cured product of the reinforcing material impregnated in the matrix composition.

The UV curable silicone-based resin acts as a binder of the matrix as a rubber compound.

The UV curable silicone-based resin may be a polyorganosiloxane having a UV curable functional group.

In the present specification, '*' represents a linking site.

In one embodiment, the UV curable silicone-based resin may include a unit of Formula 1a:

<Formula 1a>

(Wherein Ra and Rb are the same or different and are a hydrogen atom, a C1-C20 alkyl group, a C2-C20 alkenyl group, a C2-C20 alkynyl group, a C1-C20 alkoxy group, a C3-C30 cycloalkyl group, a C3-C30 cycloalkenyl group , A C3-C30 cycloalkynyl group, a C6-C30 aryl group, a C6-C30 aryloxy group or a UV curing functional group, at least one of Ra and Rb is a UV curing functional group, n is an integer of 2-1000).

The UV curable silicone-based resin may be a cyclic or linear silicone-based resin including a unit of Formula 1a or a unit of Formula 1a.

In the case of a linear silicone resin, the terminal may be of Formula 1b or Formula 1c:

&Lt; EMI ID =

R1R2R3SiO-

&Lt; Formula 1c >

R4R5R6Si-

(In the above, R1, R2, R3, R4, R5, R6 are each independently a hydrogen atom, C1-C20 alkyl group, C2-C20 alkenyl group, C2-C20 alkynyl group, C1-C20 alkoxy group, C3-C30 cycloalkyl group, C3-C30 cycloalkenyl group, C3-C30 cycloalkynyl group, C6-C30 aryl group, C6-C30 aryloxy group or UV curing functional group).

In the UV curable silicone-based resin, the UV curing functional group may be located at the end or side chain of the silicone-based resin.

In another embodiment, the UV curable silicone-based resin may include units of Formulas 2a, 2b, and 2c.

&Lt; EMI ID =

(In the above, Rc and Rd are the same or different, hydrogen atom, C1-C20 alkyl group, C2-C20 alkenyl group, C2-C20 alkynyl group, C1-C20 alkoxy group, C3-C30 cycloalkyl group, C3-C30 cycloalkenyl group , C3-C30 cycloalkynyl group, C6-C30 aryl group, C6-C30 aryloxy group, n is an integer of 2-1000).

(2b)

R7R8R9SiO-

(2c)

R10R11R12Si-

(In the above, R7, R8, R9, R10, R11, R12 are each independently a hydrogen atom, C1-C20 alkyl group, C2-C20 alkenyl group, C2-C20 alkynyl group, C1-C20 alkoxy group, C3-C30 cycloalkyl group, C3-C30 cycloalkenyl group, C3-C30 cycloalkynyl group, C6-C30 aryl group, C6-C30 aryloxy group or UV curing functional group, at least one of the R7, R8, R9, R10, R11, R12 is UV It is a curing functional group).

The UV curable silicone-based resin may be a cyclic or linear silicone-based resin including the units of Formulas 2a, 2b and 2c or consisting of units of Formulas 2a, 2b and 2c.

The UV-curing functional group may be a (meth) acrylate group, an epoxyalkoxyalkyl group (e.g., an alkyl group having 1-10 carbon atoms having 1-10 carbon atoms having an epoxy group), an epoxy group, an epoxyalkyl group -10) alkyl group, an allyl group or a vinyl group.

The UV curable silicone resin may be used in one kind or in a mixture of two or more kinds.

The UV curable silicone resin may have a weight average molecular weight of 350g / mol-50,000g / mol, preferably 350g / mol-30,000g / mol. Within this range, flexibility and mechanical properties can be expected after impregnation and curing.

The matrix composition may further include silicone urethane (meth) acrylate. The weight average molecular weight of the silicone urethane (meth) acrylate may be 350 g / mol-50,000 g / mol, preferably 350 g / mol-30,000 g / mol, more preferably 350 g / mol-10,000 g / mol. Within this range, high curing rates and mechanical properties after UV curing can be expected.

The UV curable silicone resin may be included in an amount of 1 to 99 parts by weight and the silicone urethane (meth) acrylate may be included in an amount of 1 to 99 parts by weight based on 100 parts by weight of the UV curable silicone resin and the silicone urethane (meth) acrylate. Preferably, UV-curable silicone-based resin may be included 40-60 parts by weight, silicone urethane (meth) acrylate 40-60 parts by weight. Within this range, it may have excellent heat resistance and high crosslink density.

The initiator may include a photopolymerization initiator, a photo acid generator (PAG), or a mixture thereof.

The initiator may be included in an amount of 0.01 to 10 parts by weight, preferably 0.1 to 3 parts by weight, based on 100 parts by weight of the UV curable silicone resin (or the sum of the UV curable silicone resin and the silicone urethane (meth) acrylate). Within this range, curing can be sufficient and no residual initiator is left.

A photoinitiator and a photo-acid generator can use a conventional kind without limitation.

As an embodiment, the photopolymerization initiator may include a benzophenone series, phosphorus series, triazine series, acetophenone series, thioxanthone series, benzoin series, oxime series, or a mixture thereof. For example, a benzophenone system containing 1-hydroxycyclohexyl phenyl ketone or the like can be used.

The photoacid generator may use onium salts of cations and anions which are onium ions. As a specific example of cation, triaryl sulfonium, such as diaryl iodonium, such as diphenyl iodonium and 4-methoxy diphenyl iodonium, triphenylsulfonium, and 4-phenylthiophenyl diphenyl sulfonium, etc. are mentioned. Specific examples of the anion include tetrafluoroborate (BF _4- ), hexafluorophosphate (PF _6- ), hexafluoroantimonate (SbF _6- ), hexafluoroarsenate (AsF _6- ), hexa Chloro antimonate (SbCl ₆ −) and the like.

In another embodiment, the composite sheet may be composed of a matrix composition comprising a silicone-based resin and a UV curable catalyst, and a cured product of a reinforcing material impregnated in the matrix composition.

The silicone-based resin may include a unit of Formula 3 below.

<Formula 3>

Wherein Re and Rf are the same or different and represent a hydrogen atom, a C1-C20 alkyl group, a C2-C20 alkenyl group, a C2-C20 alkynyl group, a C1-C20 alkoxy group, a C3-C30 cycloalkyl group, a C3-C30 cycloalkenyl group , C3-C30 cycloalkynyl group, C6-C30 aryl group, C6-C30 aryloxy group,

and n is an integer of 2 to 1000).

The silicone resin may be a cyclic or linear silicone resin including the units of Formula 3 or consisting of units of Formula 3.

The terminal of the silicone resin is -OSiR13R14R15 or -SiR16R17R18 (wherein R13, R14, R15, R16, R17, R18 are each independently a hydrogen atom, a C1-C20 alkyl group, a C2-C20 alkenyl group, a C2-C20 alkynyl group, C1 -C20 alkoxy group, C3-C30 cycloalkyl group, C3-C30 cycloalkenyl group, C3-C30 cycloalkynyl group, C6-C30 aryl group or C6-C30 aryloxy group).

The UV curable silicone resin may have a weight average molecular weight of 350g / mol-50,000g / mol, preferably 350g / mol-30,000g / mol. Within this range, flexibility and mechanical properties can be expected after impregnation and curing.

The silicone resin may further include the UV curing functional group.

The UV-curable catalyst is not particularly limited as long as it is a compound that is active by receiving light energy ray irradiation and promotes a hydrosilylation reaction. Examples thereof may be selected from the group consisting of platinum catalyst, ruthenium catalyst and rhodium catalyst.

The UV curable catalyst may be a diene compound.

The catalyst may include 0.001 to 1 parts by weight based on 100 parts by weight of the silicone resin. Preferably it is included in an amount of 0.01 to 0.1 parts by weight, when the amount is less than 0.001 parts by weight, the curing speed is slow, and when it exceeds 1 part by weight, it may affect the long-term storage of the cured product, and yellowing may occur on the final cured film. have.

The matrix composition may further include a crosslinker, a catalyst, and an inhibitor in addition to the above-described components.

The crosslinking agent can use the crosslinking agent normally used in manufacture of the composite sheet for flexible substrates. For example, polyorganosiloxanes having Si—CH ₃ and Si—H can be used. The crosslinking agent may be included such that the molar equivalent ratio of the number of moles of Si—H of the crosslinking agent to the number of moles of C2-C20 alkenyl groups, for example vinyl groups, of the silicone resin is 1.0 or more, preferably 1.0-1.3.

The catalyst may be a catalyst commonly used in the production of a composite sheet for a flexible substrate. For example, as the platinum-based or rhodium-based catalyst, a complex of platinum and an organic compound, a platinum and vinylated organosiloxane complex, a rhodium and an olefin complex, and the like can be used. Specifically, a vinylalkylsilane platinum complex containing Karstedt catalyst, platinum black, chloroplatinic acid, chloroplatinic acid-olefin complex, chloroplatinic acid-alcohol coordination compound, or a mixture thereof can be used.

The catalyst may be included in the weight of the metal, 2ppm-2000ppm, preferably 5ppm-500ppm with respect to the silicone resin.

The inhibitor can cure the matrix at high temperatures by inhibiting the action of the catalyst at 25 ° C. and not inhibiting it at high temperatures.

Inhibitors may be used conventionally used in the manufacture of a composite sheet for a flexible substrate. For example, inhibitors include acetylenic alcohols including dimethyl-1-hexyn-3-ol, pyridine, phosphines, organic phosphites, unsaturatedamides, dialkylcarbonylates, dialkylacetylenedicarboxylates, alkylated Maleate, diallyl maleate, or mixtures thereof. The inhibitor may be included in an amount of 100 ppm to 2500 ppm with respect to the silicone resin.

The matrix in the composite sheet may be included in 70-95% by weight, more preferably 80-90% by weight. Within this range, flexibility can be provided to the composite sheet.

The stiffener is embedded in the matrix. The reinforcement material may have a refractive index difference (absolute value of the refractive index of the reinforcement material-matrix) of the reinforcement material to be 0.01 or less. Within this range, it may have excellent transparency and light transmittance. Preferably, the refractive index difference may be 0.005 or less, more preferably 0.0001-0.005.

The reinforcing material is a group consisting of glass fiber, glass fiber cloth, glass fibric, glass nonwoven fabric, glass mesh, glass beads, glass flakes, silica particles, and colloidal silica. It may include one or more selected from. Preferably, a glass fiber cloth can be used.

Reinforcing material in the composite sheet may be included in 5-30% by weight, preferably 10-20% by weight. Within this range, it is possible to ensure high heat resistance and mechanical properties of the flexible substrate, and to improve transparency, flexibility and light weight.

The composite sheet manufacturing method according to another aspect of the present invention can be prepared by UV curing the composition for the matrix containing the silicone resin and the reinforcing material impregnated in the composition for the mattress.

In one embodiment, preparing a composition for a matrix comprising a UV-curable silicone-based resin and an initiator; And impregnating a reinforcing material into the composition and UV curing.

In another embodiment, to prepare a composition for a matrix comprising a silicone-based resin and a UV curing catalyst; And impregnating a reinforcing material into the composition and UV curing.

Specifically, the composition for a matrix can be impregnated with a reinforcing material, laminated and then UV cured to produce the composition. UV curing may be performed by irradiation of the irradiation dose, 0.01 cho -10 minutes of ^{500mJ / cm 2 -10,000mJ / cm 2} , but is not limited thereto.

The manufacturing method may further comprise the step of heat treatment after UV curing. The heat treatment includes treating at 25 ° C.-150 ° C. for 0.1-5 hours. The heat treatment after UV curing can impart an aging effect.

The manufacturing method may further comprise heat treatment after impregnating the reinforcing material and before UV curing (that is, between impregnation and UV curing). The heat treatment includes treating at 25 ° C.-150 ° C. for 0.1-5 hours. The heat treatment between impregnating the reinforcement and UV curing may impart a heat curing effect.

Details of the composition for the matrix and the reinforcing material are as described above.

The composite sheet prepared by the manufacturing method may have a surface roughness (Ra) of 100 nm or less, preferably 50 nm or less, and more preferably 5 nm-50 nm.

The composite sheet manufactured by the above method may have a young, s modulus of 1 MPa-200 MPa, preferably 1 MPa-150 MPa.

In another aspect of the present invention, the flexible substrate and the display device including the same may include the composite sheet. Flexible substrate is used for display or optical element such as substrate for liquid crystal display (LCD), substrate for color filter, substrate for organic EL display, substrate for solar cell, substrate for touch screen panel It can be used as.

Hereinafter, the present invention will be described in more detail by way of examples, but these examples are for illustrative purposes only and should not be construed as limiting the present invention.

Manufacturing example  One: D4MA Synthesis and manufacturing

D1silane (1,3,5,7-tetramethyl cyclotetrasiloxane) and allyl methacrylate were added in a molar ratio of 1: 1.1 equivalents, 1 wt% Pt catalyst (Karstedt catalyst) and 10 mol% hydroquinone (inhibitor) compared to allyl methacrylate. After reacting by reflux at 70 ° C. under toluene solvent. Thereafter, toluene was removed and filtered to obtain D4MA (methacryl group-containing cyclic organosiloxane).

Manufacturing example  2: silicone ( PDMS Synthesis and Preparation of Resin Matrix

Synthesis was performed using phenylmethyl dimethoxy siloxane (PMDMS), dimethyl dimethoxy siloxane (DMDMS), and vinyl trimethoxy siloxane (VTMS). After PDMDS, DMDMS and VTMS were weighed ((PMDMS + DMDMS): VTMS weight ratio 95: 5) hydrolysis was performed under deionized water and KOH for 1 hour at 70 ℃. After the reaction was conducted at 90 ° C., toluene and water were added to reduce the temperature to 25 degrees and washed with water. After that, Vi-MM (1,1,3,3, -tetramethyl-1,3-divinyl disiloxane) was added to carry out endcapping at 50 ° C. for about 5 hours, washed with water at 25 ° C., and solvent removed. The final PDMS resin (phenyl group, methyl group, vinyl group-containing polyorganosiloxane resin) was synthesized. (PMDMS + DMDMS): Two kinds of PMDMS and DMDMS contents were synthesized by using VTMS as a constant ratio, and two PDMS were mixed and used to match refractive index with D-glass cloth.

Manufacturing example  3: Manufacture of catalyst system A

Karstedt catalyst (PT-CS-1.8CS, Umicore) and inhibitor surfynol were used as a catalyst.

Example  One

D4MA and Miramer SIU1000 (Miwon, Mw 530g / mol, slilicone urethane acrylate) of Preparation Example 1 were mixed in a weight ratio of 40wt% / 60wt%. The composition for a matrix was prepared by adding 1 wt% of initiator Igacure184. After impregnating and laminating the glass fiber cloth (D-glass cloth), a composite sheet was prepared by irradiating UV (mercury lamp, 5000mJ / cm ² ) for 1 minute.

Example  2

PMS-E11 (Gelest, epoxypropoxypropyl terminated polyphenylmethylsiloxane, Mn 500g / mol) and DMS-E09 (Gelest, epoxypropoxypropyl terminated polydimethylsiloxane, Mn 350g / mol) were mixed at a weight ratio of 40wt% / 60wt%. 1 wt% of the photoacid generator CPI-210S was added to impregnate the glass fiber cloth and laminated in the same manner as in Example 1, and then irradiated with UV (mercury lamp, 5000 mJ / cm ² ) for 1 minute to proceed with curing. Thereafter, heat treatment was further performed at 100 ° C. for 1 hour to prepare a composite sheet.

Example  3

After blending HMS-501 (Gelest) with Si-H / vinyl molar ratio 1.2 to the PDMS resin of Preparation Example 2 with a Si-H / vinyl molar ratio of 1.2, UV-curable platinum catalyst was added to 0.05 wt%, impregnated with glass fiber cloth, and laminated, followed by UV for 1 minute. Irradiation (mercury lamp, 5000mJ / cm ² ) to prepare a composite sheet.

Comparative Example  One

0.05 wt% of the catalyst system A was added to the PDMS resin of Preparation Example 2, the glass fiber cloth was impregnated, and a high temperature curing (10 minutes at 80 ° C.) was performed to prepare a composite sheet.

Comparative Example  2

0.05 wt% of the catalyst system A was added to the PDMS resin of Preparation Example 2, the glass fiber cloth was impregnated, and room temperature curing (10 hours at 25 ° C.) was performed to prepare a composite sheet.

The physical properties of the composite sheet prepared above were evaluated and shown in Table 1.

(1) Thermal expansion coefficient (CTE) (ppm / ℃): After measuring the dimensional change with temperature according to the ASTM E 831 method using Thermo-mechanical Aanlysizer (Expansion mode, Force 0.05N), the temperature change (30- The CTE (ppm / ° C) of the sample was obtained from the change curve of the sample length according to 250 ° C).

(2) Young, s modulus (Mpa): Indentation modulus was measured using a micro indentor (Fischer, H100).

(3) Surface roughness (Ra, nm): It was measured by non-contact using an optical profiler. The composite sheet measured 5 points using NT1100 (Veeco) in the area of 1.2 mm x 9 mm, and averaged it.

Thermal Expansion Coefficient (ppm / ° C) Young, s modulus (MPa) Surface roughness (Ra, nm) Curing time Example 1 5 150 40 to 50 1 minute Example 2 5 20 40 to 50 1 minute Example 3 5 3 40 to 50 1 minute Comparative Example 1 5 1.5 150 ~ 200 10 minutes Comparative Example 2 5 1.5 40 to 50 10 hours

As shown in Table 1, even though the composite sheet of the present invention was produced over a short time, the surface roughness was improved. On the other hand, the composite sheet of Comparative Example 1 prepared by curing at high temperature was prepared in a short time, but the surface roughness value was high. In addition, the composite sheet of Comparative Example 2 prepared by curing at room temperature was produced over a long time, although the surface roughness value is low.

Simple modifications or changes of the present invention can be easily carried out by those skilled in the art, and all such modifications or changes can be seen to be included in the scope of the present invention.

Claims (16)

A composite sheet comprising a cured product of a matrix composition comprising a UV curable silicone resin and an initiator, and a reinforcing material impregnated in the matrix composition. A composite sheet comprising a cured product of a matrix composition comprising a silicone-based resin and a UV curable catalyst and a reinforcing material impregnated in the matrix composition. The composite sheet according to claim 1 or 2, wherein the composite sheet has a Young's modulus of 1 MPa to 200 MPa and a surface roughness Ra of 50 nm or less. The composite sheet of claim 1, wherein the UV curable silicone-based resin comprises at least one of a (meth) acrylate group, an epoxy group, an epoxyalkoxyalkyl group, an epoxyalkyl group, an allyl group, and a vinyl group. The composite sheet of claim 1, wherein a weight average molecular weight of the UV curable silicone resin is 350 g / mol-50,000 g / mol. The composite sheet of claim 1, wherein the composition further comprises silicone urethane (meth) acrylate. The composite sheet of claim 6, wherein the weight average molecular weight of the silicone urethane (meth) acrylate is 350 g / mol-50,000 g / mol. The composite sheet of claim 1, wherein the initiator is a photopolymerization initiator, a photoacid generator, or a mixture thereof. The composite sheet of claim 2, wherein the silicone resin comprises a polyorganosiloxane resin including a unit of Formula 3 below:
(3)

(Wherein Re and Rf are the same or different from each other, hydrogen atom, C1-C20 alkyl group, C2-C20 alkenyl group, C2-C20 alkynyl group, C1-C20 alkoxy group, C3-C30 cycloalkyl group, C3-C30 cyclo Alkenyl group, C3-C30 cycloalkynyl group, C6-C30 aryl group, C6-C30 aryloxy group, n is an integer of 2 to 1000). The composite sheet of claim 2, wherein the UV curable catalyst is a platinum-based, rhodium-based, and ruthenium-based diene-based compound. The glass fiber of claim 1 or 2, wherein the reinforcing material is glass fiber, glass fiber cloth, glass fibric, glass nonwoven fabric, glass mesh, glass beads, glass flakes. (glass flake), silica particles and colloidal silica composite sheet comprising one or more selected from the group consisting of. To prepare a composition for a matrix comprising a UV-curable silicone resin and an initiator,
Impregnating a reinforcing material in the composition, and comprising a step of UV curing. Preparing a matrix composition comprising a silicone-based resin and a UV curable catalyst; And impregnating a reinforcing material into the composition, and UV curing. The method according to claim 12 or 13, further comprising heat treating after the UV curing or after impregnating the reinforcing material and before UV curing. A flexible substrate comprising the composite sheet of any one of claims 1 to 11. A display device comprising the flexible substrate of claim 15.

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