WO2014104655A1 - Composite sheet, and display device including same - Google Patents

Abstract

The present invention relates to a composite sheet comprising a matrix and a reinforcing material impregnated with said matrix, wherein the matrix contains a polysiloxane-polycarbonate copolymer and the refractive index difference between the matrix and the reinforcing material is less than 0.01, and the present invention also relates to a display device including same.

Description

Composite sheet and display device including same

The present invention relates to a composite sheet and a display device including the same.

Glass which is excellent in heat resistance and transparency and has a low coefficient of linear expansion is widely used as a liquid crystal display element, an organic EL display element substrate, a color filter substrate, a solar cell substrate, and the like. Recently, miniaturization, thinning, weight reduction, impact resistance, and flexibility are required as substrate materials for display elements, and plastic substrates are in the spotlight as materials for replacing glass substrates.

Recently, materials such as polycarbonate (PC), polysiloxane, polyethylene terephthalate (PET), polyethersulfone (PES), polyethylene naphthalate (PEN), polyarylate (PAR), and polyimide (PI) are used as plastic substrates. It is used.

Plastic substrate using polycarbonate is a representative engineering plastic, and has high mechanical properties, impact resistance, dimensional stability, and heat resistance, and thus has a wide range of applications such as electric and electronic materials, electronic product exterior materials, display materials, and automobile parts. In this regard, Korean Patent Publication No. 2010-0118942 discloses a glass fiber reinforced polycarbonate resin including a polycarbonate resin, a brominated flame retardant, and a glass fiber reinforcement coated with urethane. However, it is not easy to match the refractive indices of polycarbonate and glass fiber. In addition, a plastic substrate using glass fibers and polycarbonate has a problem that yellowness, turbidity, and bending resistance are not good.

In addition, the polysiloxane may be prepared by matching the refractive index with the glass fiber, but the substrate prepared therefrom has a problem in that the transparency and the bending resistance are good, but the surface strength is very low.

An object of the present invention is to provide a composite sheet having excellent surface hardness, flex resistance and light transmittance while ensuring transparency compared to a composite sheet having a polycarbonate or polysiloxane as a matrix.

Another object of the present invention is to provide a composite sheet having low yellowness (YI) and low turbidity (Haze).

Another object of the present invention is to improve the adhesion between the matrix and the reinforcing material, to provide a composite sheet having high bending resistance, low yellowness and turbidity.

Still another object of the present invention is to provide a composite sheet having excellent transparency, surface hardness, flex resistance, and light transmittance by including a copolymer having easy refractive index matching with a reinforcing material in a matrix.

It is another object of the present invention to provide a composite sheet free of bubbles and cracks.

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

A composite sheet according to an aspect of the present invention includes a matrix and a reinforcing material impregnated in the matrix, wherein the matrix includes a cured product of a composition including a polysiloxane-polycarbonate copolymer, and a difference in refractive index between the matrix and the reinforcing material is It may be less than 0.01.

Another aspect of the invention the device may comprise the composite sheet.

The present invention provides a composite sheet having excellent surface hardness, bending resistance and light transmittance while ensuring transparency while including a reinforcing material such as glass fiber and a copolymer having easy refractive index matching in a matrix. In addition, the present invention improves the adhesive force between the matrix and the reinforcing material, to provide a composite sheet having high bending resistance, low yellowness and turbidity. In addition, the present invention provides a composite sheet free of bubbles and cracks.

1 is a cross-sectional view of a composite sheet according to an embodiment of the present invention.

Hereinafter, a composite sheet according to an embodiment of the present invention will be described with reference to FIG. 1. 1 is a cross-sectional view of a composite sheet according to an embodiment of the present invention.

Referring to FIG. 1, the composite sheet 10 according to an exemplary embodiment of the present invention has a structure in which a reinforcing material 2 is included in a matrix 1.

The matrix 1 may be made of a composition comprising a copolymer comprising polysiloxane units. For example, the copolymer including the polysiloxane unit may be a polysiloxane-polycarbonate copolymer. The polysiloxane-polycarbonate copolymer is included in the matrix composition for producing a composite sheet, and the refractive index matching with the reinforcing material including glass fibers and the like relative to other resins is very easy.

The polysiloxane-polycarbonate copolymer can have a refractive index of 1.50 to 1.70, such as 1.56 to 1.57. Within this range, the transparency of the composite sheet may be improved by reducing the difference between the matrix, the reinforcing material, and the refractive index when manufacturing the composite sheet.

In the composite sheet according to the embodiment of the present invention, the refractive index difference between the matrix and the reinforcing material may be less than 0.01, for example, 0.001 or more and less than 0.01, specifically, 0.001 to 0.005. By securing such a difference in refractive index, the composite sheet according to the embodiment of the present invention has good light transmittance and transparency, as demonstrated by transmittance of 88% or more at a wavelength of 550 nm, and both yellowness and turbidity may be reduced.

The polysiloxane-polycarbonate copolymer has a high adhesive strength to a reinforcing material including glass fibers and the like compared to other resins. This improved adhesion can increase the flex resistance and surface hardness of the composite sheet, it can lower the yellowness and turbidity. Regarding the flex resistance, the composite sheet according to the embodiments of the present invention did not generate whitening phenomenon even at 10,000 times when the composite sheet was folded once per second at 10 mm intervals for a 100 μm thick specimen. On the other hand, the composite sheet having the same thickness including polycarbonate in the matrix had a whitening phenomenon at 700 or more times, and the same thickness including the polysiloxane-polycarbonate copolymer not containing the polysiloxane unit of Formula 1 in the matrix. The composite sheet also had whitening phenomenon more than 2000 times. In relation to the surface hardness, the composite sheet according to an embodiment of the present invention may have a pencil hardness of HB or 1B or more. In contrast, the composite sheet including polysiloxane or a polysiloxane-polycarbonate copolymer not containing the polysiloxane unit of Formula 1 in the matrix was so low in surface hardness that pencil hardness could not be measured.

The glass transition temperature of the polysiloxane-polycarbonate copolymer may be 150 ° C. or less, for example, 100 to 150 ° C., specifically 140 to 150 ° C. Within this range, there may be an effect of reducing the coefficient of thermal expansion.

The polysiloxane-polycarbonate copolymer includes the polysiloxane unit, and the polysiloxane unit may be included in the main chain of the copolymer at 0.1 to 20% by weight, for example 5 to 15% by weight. Within this range, the flex resistance may be improved when included in the composite sheet.

The polymerization ratio (based on weight) of the polysiloxane: polycarbonate in the polysiloxane-polycarbonate copolymer may be 1: 0.1 to 1: 5. Within this range, the refractive index matching with the reinforcing material may be easy, thereby increasing the transparency and light transmittance of the composite sheet, it is possible to increase the bending resistance and surface hardness. For example, the polymerization ratio may be 1: 4 to 1: 4.5.

The polysiloxane-polycarbonate copolymer can be linear, branched, or graft, but can have a linear structure, for example.

In the polysiloxane-polycarbonate copolymer, the polysiloxane unit may be represented by the following Chemical Formula 1:

<Formula 1>

Wherein R ₁ and R ₂ are each independently hydrogen, C 1 -C 10 alkyl group, C 6 -C 18 aryl group, C 1 -C 10 alkyl group having halogen or C 1 -C 10 alkoxy group, or halogen or C 1 -C 10 alkoxy A C6-C18 aryl group having a group, A and B are each independently a substituted or unsubstituted C2-C20 hydrocarbon group, or a substituted or unsubstituted C2-C20 hydrocarbon group having -O- or -S- Z is a substituted or unsubstituted C1-C24 hydrocarbon group or a substituted or unsubstituted C1-C24 hydrocarbon group including an ester bond, a urethane bond, or a combination thereof, and Y is each independently a hydrogen atom , A halogen, a C1-C18 halogenated alkyl group, a cyano group, or an ester group of C1-C18, m and n are each independently an integer of 4 to 100, * is a linking group.

In this specification, "substituted" is a hydrogen atom of a halogen group, C1-C30 alkyl group, C1-C30 haloalkyl group, C6-C30 aryl group, C2-C30 heteroaryl group, C1-C20 alkoxy group, combinations thereof It means what was substituted by substituents, such as these. For example, R ₁ and R ₂ may be C ₁ -C 5 alkyl groups. For example, A and B may be C2-C20 alkylene groups, specifically, C2-C10 alkylene groups. For example, Z can be an alkylene group of C 1 -C 20, specifically an alkylene group of C 2 -C 10. For example, m + n can be 40 to 100.

The polysiloxane unit of Formula 1 may be derived from Formula 2:

<Formula 2>

(Wherein R ₁ , R ₂ , A, B, Z, Y, m and n are as defined in Formula 1 above).

For example, the polysiloxane unit of Formula 1 may be derived from Formula 3:

<Formula 3>

(In the above, m and n are each independently an integer of 4 to 100).

The method for preparing the polysiloxane unit may be prepared, for example, by preparing a polysiloxane represented by Chemical Formula 2 by reacting a monohydroxysiloxane represented by Chemical Formula 6 with a diene (second step). . Here, the monohydroxysiloxane represented by Formula 6 may be prepared by reacting a siloxane terminated with a hydride represented by Formula 4 with a phenol derivative represented by Formula 5 below (first step).

<Formula 4>

<Formula 5>

<Formula 6>

In Formulas 4 to 6, R ₁ , R ₂ , A, Y and m are as defined in Formula 1, D is a substituted or unsubstituted C2-C20 hydrocarbon group having a double bond, or -O- Or a substituted or unsubstituted C2-C20 hydrocarbon group wherein the terminal having -S- is a double bond.

For example, D has a substituted or unsubstituted C2-C20 alkylene group having a double bond at the terminal, a substituted or unsubstituted C6-C20 arylene group having a double bond at the terminal, or -O- or -S- Substituted or unsubstituted C2-C20 alkylene group having a double bond or substituted or unsubstituted C6-C20 arylene group having a double bond, for example, C2-C10 alkylene group having a double bond, As the C2-C6 alkylene group having a double bond, more specifically, an allyl group (* -CH ₂ -CH = CH ₂ , wherein * is a linking group to the benzene group of Formula 5). Here, D of the phenol derivative may react with siloxane terminated with hydride to form A of monohydroxysiloxane.

As the compounds represented by Formulas 4 to 6, two or more compounds having different R ₁ , R ₂ , A, D, Y, and m may be used, respectively, and A, m, and the like may be represented by Formula 6 different from each other. The compound may react with diene to represent A, B, m, n, and the like of the compound represented by Chemical Formula 2.

In embodiments, the hydroxyl group (-OH) groups of Formula 5 and 6 may be bonded to the position 2 of the benzene moiety.

Hereinafter, the manufacturing method of the said polysiloxane is demonstrated concretely.

First step

The first step is a step of synthesizing the monohydroxysiloxane represented by Chemical Formula 6 by reacting the siloxane terminated with the hydride represented by Chemical Formula 4 and the phenol derivative represented by Chemical Formula 5 in the presence of a catalyst.

As the catalyst, a catalyst containing platinum may be used. For example, the catalyst may be a platinum element itself or a compound comprising platinum, for example H ₂ PtCl ₆ , Pt ₂ {[(CH ₂ = CH) Me ₂ Si] ₂ O} ₃ , Rh [ (cod) ₂ ] BF ₄ , Rh (PPh ₃ ) ₄ Cl, Pt / C and the like can be used alone or in combination, but is not limited thereto. Specifically, Pt / C, for example 10% Pt / C, may be used.

The amount of the catalyst used may be 10 to 500 ppm, for example, 50 to 150 ppm with respect to the entire reactant.

The reaction may be performed in an organic solvent, and examples of the organic solvent may include, but are not limited to, 1,2-dichloroethane, toluene, xylene, dichlorobenzene, mixed solvents thereof, and the like. For example, it may be performed in toluene.

The reaction may control the reaction temperature and reaction time according to the reactivity of the reactants (Formula 4 and Formula 5). The reaction may be carried out at a reaction temperature of 60 to 140 ℃, for example 110 to 120 ℃, for 2 to 12 hours, for example 3 to 5 hours.

The compound of formula 4 prepared in the first step may be purified and used in the next step or in situ in the next step without further purification.

2nd step

The second step is to prepare a polysiloxane represented by the formula (2) by reacting the monohydroxysiloxane represented by the formula (6) and the diene.

The diene is a substituted or unsubstituted C1-C20 hydrocarbon group, or a substituted or unsubstituted C1-C20 hydrocarbon group including an ester bond, a urethane bond, or a combination thereof, for example, an ester bond, a urethane bond Or a substituted or unsubstituted C1-C20 alkylene group, a substituted or unsubstituted C6-C20 cycloalkylene group, or a substituted or unsubstituted C6-C20 arylene group, with or without combinations thereof. It may be diene.

After completing the first step, the polysiloxane represented by Chemical Formula 2 may be prepared by reacting in situ by adding the diene without purifying the monohydroxysiloxane represented by Chemical Formula 6.

In the reaction of monohydroxyarylsiloxane and diene, the reaction temperature and reaction time can be appropriately controlled. For example, the reaction temperature and reaction time used in the first step may be used as it is, but is not limited thereto.

The polysiloxane prepared can be purified and obtained through conventional methods. For example, after completion of the second step, the reaction product is filtered to remove the catalyst, and the obtained filtrate is concentrated to remove the reaction solvent and the by-product of low molecular weight, thereby obtaining the polysiloxane represented by Chemical Formula 1. Depending on the purity of the polysiloxane, further purification may be carried out.

The polycarbonate-polysiloxane copolymer may be a copolymer of a polysiloxane represented by Chemical Formula 2, an aromatic dihydroxy compound, for example, an aromatic dihydroxy compound and a phosgene-based compound represented by the following Chemical Formula 7.

<Formula 7>

In Formula 7, A ₁ is a single bond, a substituted or unsubstituted C1-C5 alkylene group, a substituted or unsubstituted C1-C5 alkylidene group, a substituted or unsubstituted C3-C6 cycloalkylene group, substituted Or an unsubstituted C5-C6 cycloalkylidene group, CO, S, and SO2, R ₃ and R ₄ are each independently a substituted or unsubstituted C 1 -C 30 alkyl group, and substituted or unsubstituted It is selected from the group consisting of a substituted C6-C30 aryl group, a and b are each independently an integer of 0 to 4.

Specific examples of the aromatic dihydroxy compound include 4,4'-dihydroxydiphenyl, 2,2-bis- (4-hydroxyphenyl) -propane, 2,4-bis- (4-hydroxyphenyl ) -2-methylbutane, 1,1-bis- (4-hydroxyphenyl) -cyclohexane, 2,2-bis- (3-chloro-4-hydroxyphenyl) -propane, 2,2-bis- (3,5-dichloro-4-hydroxyphenyl) -propane etc. can be illustrated. For example, as the aromatic dihydroxy compound, 2,2-bis- (4-hydroxyphenyl) -propane, 2,2-bis- (3,5-dichloro-4-hydroxyphenyl) -propane, or 1,1-bis- (4-hydroxyphenyl) -cyclohexane can be used, and 2,2-bis- (4-hydroxyphenyl) -propane also specifically called bisphenol-A can be used.

The total amount of polysiloxane represented by Formula 2 is 0.1 to 20 parts by weight, for example 5 to 15 parts by weight, based on 100 parts by weight of the total amount of polysiloxane and aromatic dihydroxy compound represented by Formula 2, and the aromatic di The content of hydroxy compound is 80 to 99.9 parts by weight, for example 85 to 95 parts by weight.

Examples of the phosgene-based compound used in the present invention include, but are not limited to, phosgene, triphosgene, diphosgene, and the like.

In a specific embodiment, in the method for preparing the polycarbonate-polysiloxane copolymer, an aromatic dihydroxy compound is added to a basic aqueous solution, an organic solvent, a polysiloxane represented by Formula 2 is added and mixed, and a phosgene-based compound is added. It can be prepared by interfacial polymerization. By applying the interfacial polymerization in this way, it is possible to secure remarkably excellent transparency compared to the melt polymerization.

The polysiloxane-polycarbonate copolymer in the composite sheet may be included in 5 to 40% by weight, for example, 5 to 30% by weight. Within this range, transparency, light transmittance, bending resistance, and surface strength of the composite sheet may be improved. That is, the polysiloxane-polycarbonate copolymer: reinforcing material may be included in a weight ratio of 5: 95 to 40: 60. By controlling the composition ratio of the polysiloxane-polycarbonate copolymer and the reinforcing material in the composite sheet, the refractive index of the copolymer and the reinforcing material is controlled, and the composite sheet prepared therefrom is prepared compared to using a conventional resin (for example, polycarbonate and polysiloxane alone). Light transmittance, surface hardness and flex resistance can be very excellent.

The reinforcement 2 can be included in the matrix 2 in a dispersed, single layer or multiple layer structure.

The reinforcement in the composite sheet may have a refractive index of 1.50 to 1.57, for example, 1.56 to 1.57. Within this range, refractive index matching with the polysiloxane-polycarbonate copolymer can be facilitated.

The thickness of the reinforcement may be 10 μm to 200 μm. The 'thickness' may mean the thickness of the fiber when the reinforcing material in the form of a fiber, the thickness of the woven fabric when the fiber is woven form, but is not limited thereto.

The reinforcing material may be at least one of glass fiber, glass fiber cloth, glass fabric, glass nonwoven fabric, and glass fiber mesh. For example, it may be a glass fiber cloth.

Glass fiber cloth may vary in thickness, refractive index, etc., depending on the raw material component, thickness, shape, weaving and weft shape of the glass fiber, the number of glass fibers per bundle, etc., and may be selected from among them.

The composite sheet thickness may be 15 μm to 200 μm. In the above range, it can be used as a composite sheet for flexible substrate applications.

The composite sheet may have a thermal expansion coefficient of 0 ppm / ° C. to 400 ppm / ° C., for example, 0 ppm / ° C. to 10 ppm / ° C., specifically 3 ppm / ° C. to 7 ppm / ° C., measured by ASTM E 831. Within this range, thermal deformation can be suppressed in manufacturing the flexible substrate.

The composite sheet may have a surface roughness Ra of 100 nm or less, for example, 50 nm or less, specifically 5 nm to 50 nm.

The composite sheet may have a transmittance of 88% or more, for example, 88 to 99% at a wavelength of 550 nm.

Composite sheet according to an embodiment of the present invention is excellent in both surface hardness, bending resistance and light transmittance while ensuring transparency compared to the composite sheet of a polycarbonate resin or a polysiloxane resin matrix. Therefore, the composite sheet can be applied as a substitute for glass, for example, an optical sheet such as a liquid crystal display device substrate, a flexible substrate, an organic EL display device substrate, a color filter substrate, a solar cell substrate, a transparent sheet, an optical lens, an optical device. , OLED encapsulating material, cover glass, display multilayer thin film and the like can be used.

According to another aspect of the present invention, a method for manufacturing a composite sheet may include curing a composition for a matrix including a copolymer including the polysiloxane unit, and a reinforcing material impregnated in the composition for the matrix.

Specifically, (A) preparing a copolymer comprising the polysiloxane unit, (B) impregnating a reinforcing material in the composition comprising the copolymer, and (C) laminating the composition and the reinforcing material.

The method for producing a copolymer including the polysiloxane unit is as described above. In this case, it is important to match the refractive index of the copolymer with the refractive index of the reinforcing material, and the polymerization ratio (based on weight) of the polysiloxane: polycarbonate may be 1: 0.1 to 1: 5. The copolymer is dissolved in a conventional organic solvent (eg methylene chloride, THF) and then impregnated with a reinforcing material. Then, the composition and the reinforcing material is cured through a laminating process to produce a composite sheet. Laminating conditions are not particularly limited.

According to another aspect of the present invention, a display device may include the composite sheet. Examples of the display apparatus include a liquid crystal display device substrate, a flexible substrate, an organic EL display device substrate, a color filter substrate, a solar cell substrate, an optical sheet, a transparent sheet, an optical lens, an optical device, an LED encapsulant, a cover glass, and a display multilayer thin film. It may include one or more, but is not limited thereto.

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

Preparation Example 1 Preparation of Polysiloxane

344.5 g (1.16 mol) of octamethylcyclotetrasilane, 52.0 g (0.375 mol) of tetramethyldisilane, and 500.0 ml of trifluoromethanesulfonic acid were added to the reaction vessel and stirred at 25 ° C for 24 hours. 14 g of MgO was added and stirred for 1 hour. The stirred reaction product was filtered, and then unreacted material was removed under high temperature vacuum to obtain 300 g of oligodimethylsiloxane. Pt / C 0.5g was added to 300g of the oligodimethylsiloxane and 270ml of toluene, followed by stirring and heating to 110 ° C. Next, a mixed solution of 28.2 g (0.21 mol) of 2-allylphenol and 30 ml of toluene was slowly added dropwise. After 2-allylphenol was added dropwise, 9 g (0.11 mol) of 1,5-hexadiene was added dropwise, stirred at 110 ° C for 1 hour, and then cooled to 25 ° C. After the reaction was filtered, the unreacted material was removed under a high temperature vacuum to obtain 320 g of polysiloxane A represented by the following Chemical Formula 2a in an oil state.

<Formula 2a>

(Wherein m + n is 40)

Preparation Example 2 Preparation of Polysiloxane-Polycarbonate Copolymer

7000 ml of H ₂ O, 2000 ml of 50% NaOH aqueous solution, and 1500 g (6570.6 mmol) of 2,2-bis (4-hydroxyphenyl) propane (BPA) were added to the glass stirring reactor, followed by vigorous stirring and the solution temperature of 20 to Stir for 1 hour while maintaining at 25 ° C. To this was added 41.5 g (275.9 mmol) of t-butyl phenol, 3000 ml of methylene chloride, and 112.4 g (34.2 mmol) of the polysiloxane A. Slowly introduced into the reactor for a time, and stirred for 1 hour while maintaining the solution temperature at 20 to 25 ℃. 7.8 g (77.1 mmol) of triethylamine were added thereto, and the mixture was stirred for 2 hours while maintaining the solution temperature at 30 to 35 ° C. After stirring was complete, the organic layer was separated, neutralized by addition of 7000 ml of 10% HCl solution, and then washed several times with water until the pH reached neutral. After washing, the solvent of the organic layer was lowered and dried using a trimixer (manufacturer: Inoue Co., Ltd., TX-15) to obtain a polycarbonate-polysiloxane copolymer in a powder state. As a result of DOSY (Diffusion Ordered Spectroscopy) analysis of the obtained copolymer, it was confirmed that polysiloxane was bound to the main chain of polycarbonate, and Si content was 2.1% by weight based on 1H NMR analysis. As a result of GPC analysis, the weight average molecular weight (Mw) was 20,846 and the refractive index was 1.56.

Preparation Example 3 Preparation of Polysiloxane

In Preparation Example 1, except that 52.0g (0.375mol) of tetramethyldisilane, except that 26.0g (0.129mol) of tetramethyldisilane was used in the same manner as in Preparation Example 1 to the formula 2b of the oil state Obtained 290 g of polysiloxane B.

<Formula 2b>

(In the above, m + n is 60.)

Preparation Example 4 Preparation of Polysiloxane-Polycarbonate Copolymer

In Preparation Example 2, a polycarbonate-polysiloxane copolymer in a powdered state was obtained in the same manner as in Preparation Example 2, except that 109.9 g (26.3 mmol) of Polysiloxane B (Preparation Example 3) was used instead of Polysiloxane A. . DOSY analysis of the obtained copolymer confirmed that the siloxane polymer was present in the main chain of the polycarbonate, and the Si content was 2.1% by weight based on 1H NMR analysis. As a result of GPC analysis, the weight average molecular weight (Mw) is 20,235 and the refractive index is 1.561.

Example 1

The copolymer of Preparation Example 2 was obtained as a powder in powder form, and the powder was dissolved in a solvent (Methylene chloride) and then impregnated in a glass fiber cloth (# 3313, Nittobo, refractive index: 1.56) having a thickness of 80 μm, followed by a laminating process. A composite sheet having a thickness of 100 μm was obtained through the material. At this time, the glass fiber cloth was to be included in 70% by weight based on the composite sheet.

Example 2

Obtaining the powder of the copolymer of Preparation Example 2, the powder is put into an extruder, heated to 400 ℃ to melt and extruded a 105 μm thick film through a T-die mounted on the extruder and at the same time glass fiber cloth (# 3313, Nittobo Co., Refractive Index: 1.56) was impregnated to obtain a composite sheet having a thickness of 105 µm. At this time, the glass fiber cloth was to be included in 70% by weight based on the composite sheet.

Example 3

The copolymer of Preparation Example 4 was obtained as a powder in powder form, and the powder was dissolved in a solvent (Methylene chloride) and then impregnated in a glass fiber cloth (# 3313, Nittobo, refractive index: 1.56) having a thickness of 80 μm, followed by a laminating process. Through this, a 95-micrometer-thick composite sheet was obtained. At this time, the glass fiber cloth was to be included in 70% by weight based on the composite sheet.

Example 4

The powder of the copolymer of Preparation Example 4 was obtained in a powder state, the powder was introduced into an extruder, heated to 400 ° C., melted, and a film having a thickness of 100 μm was extruded through a T-die mounted on the extruder. (# 3313, Nittobo Co., Refractive Index: 1.56) was impregnated to obtain a composite sheet having a thickness of 100 µm. At this time, the glass fiber cloth was included in 70% by weight based on the composite sheet.

Comparative Example 1

Polysiloxane (Shin-Etsu, X-22-1821, which does not include the polysiloxane unit of Formula 1) and polycarbonate were copolymerized to obtain a powder powder having a refractive index of 1.549. After dissolving the polysiloxane-polycarbonate copolymer in a solvent (Methylene chloride) and impregnated in a glass fiber cloth having a thickness of 80㎛, a composite sheet having a thickness of 95㎛ was obtained through a laminating process.

Comparative Example 2

Polysiloxane (Shin-Etsu, X-22-1821, which does not include the polysiloxane unit of Formula 1) and polycarbonate were copolymerized to obtain a powder powder having a refractive index of 1.549. After drying polysiloxane-polycarbonate, it was heated to 400 ° C., melted, and a 105 μm thick film was extruded through a T-die mounted on the extruder, and a glass fiber cloth was impregnated to prepare a composite sheet having a thickness of 105 μm. It was.

Comparative Example 3

After drying the polycarbonate chip, it is put into the extruder, heated to 400 ℃ to melt and extruded 105㎛ thick film through the T-die mounted on the extruder and impregnated glass fiber cloth to prepare a composite sheet having a thickness of 105㎛ It was.

Comparative Example 4

A two-component polyalkylarylsiloxane resin (Dow coating (OE-6630) and polysiloxane (in-house developed), containing no polysiloxane unit of Formula 1) was impregnated in a glass fiber cloth and dried to prepare a composite sheet having a thickness of 100 μm. .

The following physical properties were measured for the composite sheet.

1) Transmittance: A UV-Visible machine (JASCO V-550) was used at a wavelength of 550 nm.

2) Yellowness (YI): A color difference instrument (Konika minota company CM3600D model) was used.

3) Haze: Haze was measured using a haze meter (NDH200 from Nippon denshouku).

4) Bending test: The bending resistance is evaluated by the reciprocating motion of the moving shaft. It was evaluated whether the whitening phenomenon occurred by reciprocating the specimen having a width x length x thickness (2cmx7cmx100µm) in a [1 bending cycle / sec] condition up to 10mm interval.

5) Pencil Hardness: It was measured by an electric pencil hardness tester (Core Tech).

6) Difference in refractive index between the matrix and the reinforcing material: measured by Abbe refractometer (ABE refractometer, ATAGO).

Table 1

	Example 1	Example 2	Example 3	Example 4	Comparative Example 1	Comparative Example 2	Comparative Example 3	Comparative Example 4
matrix	Preparation Example 2 Copolymer	Preparation Example 2 Copolymer	Preparation Example 4 Copolymer	Preparation Example 4 Copolymer	Without Formula 1	Without Formula 1	Polycarbonate	Without Formula 1
Sheet thickness (㎛)	100	105	80	100	80	105	105	100
Transmittance (%)	90.2	89.9	88.5	89	82	81.7	31	90
Yellow road	3.7	3.2	2.9	3.0	9.7	9.8	Not measurable	2.3
Turbidity	1.2	1.5	1.3	1.9	12	11	50	1.9
Flex resistance	10000 times or more	10000 times or more	10000 times or more	10000 times or more	2000 bleaching occurrence	2200 times bleach	700 times bleach	10000 times or more
Pencil hardness	1B	HB	HB	HB	Not measurable	Not measurable	1B	Not measurable
Refractive index difference	0.001	0.002	0.002	0.002	0.01	0.01	-	0.001

As shown in Table 1, in the composite sheet according to the embodiment of the present invention, it is easy to set the difference in refractive index between the matrix, in particular the copolymer and the reinforcing material, to less than 0.01. It increased, yellowness and turbidity decreased, and bending resistance was good.

On the other hand, the composite sheet of Comparative Example 3 including a matrix of polycarbonate was not good bend resistance easily whitening phenomenon occurred in the bending test. The composite sheet of Comparative Example 4 containing a matrix of polysiloxane had excellent flex resistance but very poor surface hardness. In addition, the composite sheets of Comparative Examples 1 to 2 including the matrix of the polysiloxane-polycarbonate copolymer had difficulty in matching the refractive index of the copolymer and the reinforcing material, and yellowness and turbidity were also observed in Comparative Examples 1 to 2 in which the refractive index difference was minimized. It was high, and the flex resistance and the surface hardness were not good.

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 (14)

1. A matrix and a reinforcement impregnated in said matrix,

   The matrix comprises a polysiloxane-polycarbonate copolymer

   The composite sheet of less than 0.01 refractive index difference between the matrix and the reinforcing material.
2. The composite sheet of claim 1, wherein the polysiloxane-polycarbonate copolymer comprises a polysiloxane unit of Formula 1

   <Formula 1>

   

   Wherein R ₁ and R ₂ are each independently a C1-C10 alkyl group, a C6-C18 aryl group, or a C1-C10 alkyl group or a C6-C18 aryl group having a halogen or a C1-C10 alkoxy group, A and B are each independently a substituted or unsubstituted C2-C20 hydrocarbon group, or a substituted or unsubstituted C2-C20 hydrocarbon group having -O- or -S-, and Z is a substituted or unsubstituted C1 -A C24 hydrocarbon group, or a substituted or unsubstituted C1-C24 hydrocarbon group including an ester bond, a urethane bond, or a combination thereof, each independently a hydrogen atom, a halogen, a halogenated alkyl group of C1-C18, A cyano group or an ester group of C1-C18, m and n each independently represent an integer of 4 to 100, and * is a linking group).
3. The composite sheet of claim 2, wherein the polysiloxane unit is included in an amount of 0.1 to 20 wt% in the main chain of the copolymer.
4. The composite sheet of claim 2, wherein a polymerization ratio based on the weight of the polysiloxane: polycarbonate in the copolymer is 1: 0.1 to 1: 5.
5. The composite sheet of claim 1, wherein the copolymer has a refractive index of 1.50 to 1.60 after curing.
6. The composite sheet of claim 1, wherein the copolymer in the composite sheet is included in an amount of 5 to 40 wt%.
7. The composite sheet of claim 1, wherein the copolymer has a glass transition temperature of 100 to 150 ° C.
8. The composite sheet of claim 1, wherein the copolymer is a copolymer of a polysiloxane, an aromatic dihydroxy compound, and a phosgene-based compound represented by Formula 2 below:

   <Formula 2>

   

   (Wherein R ₁ , R ₂ , A, B, Z, Y, m and n are as defined above).
9. The composite sheet of claim 8, wherein the aromatic dihydroxy compound is represented by Formula 7:

   <Formula 7>

   

   (In the above, A ₁ is a single bond, substituted or unsubstituted C1-C5 alkylene group, substituted or unsubstituted C1-C5 alkylidene group, substituted or unsubstituted C3-C6 cycloalkylene group, substituted or An unsubstituted C5-C6 cycloalkylidene group, one or more of CO, S and CO ₂ , R ₃ and R ₄ each independently represent a substituted or unsubstituted C 1 -C 30 alkyl group, or a substituted or unsubstituted C 6 Is selected from an aryl group of -C30, and a and b are each independently an integer of 0 to 4).
10. The composite sheet of claim 1, wherein a refractive index of the reinforcing material is 1.50 to 1.57.
11. The composite sheet of claim 1, wherein the reinforcing material has a thickness of 10 μm to 200 μm.
12. The composite sheet of claim 1, wherein the reinforcing material is at least one of glass fiber, glass s fiber cloth, glass fabric, glass nonwoven fabric, and glass fiber mesh.
13. The composite sheet of claim 1, wherein the composite sheet has a pencil hardness of HB or 1B or more measured by an electric pencil hardness tester.
14. Display device comprising the composite sheet of claim 1.

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