KR20170003181A - Curved Type Transparent Plastic Sheet And Method For Manufacturing The Same - Google Patents

Abstract

The present invention relates to a method for manufacturing a curved transparent plastic sheet, which comprises the following steps: (S1) carrying out co-extrusion of polycarbonate (PC) and polymethyl methacrylate (PMMA) to obtain a substrate sheet; (S2) applying a hard coating composition to the substrate sheet obtained from step (S1) with the poly(methyl methacrylate) as the top surface thereof; (S3) drying and curing the hard coating composition applied in step (S2) to form a sheet having a hard coating layer thereon; and (S4) mounting the sheet obtained from step (S3) to the lower mold of a compression molding device provided with a mold having a curved surface portion, preheating the sheet, and pressurizing the preheated sheet with the upper mold to carry out molding of a sheet. According to the present invention, it is possible to obtain a curved transparent plastic sheet having excellent surface hardness and impact resistance while comprising a curved surface portion. The present invention also relates to a liquid crystal display device comprising the curved transparent plastic sheet.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a curved transparent plastic sheet,

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transparent plastic sheet and a method of manufacturing the same. More specifically, the present invention relates to a curved transparent plastic sheet that can be applied to a cover sheet for protecting a front surface or a rear surface of a display including a curved surface portion.

According to recent trends, various display devices such as LCDs, PDPs, mobile phones, and projection televisions have greatly developed, and these display devices are becoming increasingly sophisticated and diversified in design to attract consumers' attention. Particularly, in terms of design, manufacturers of competing schemes are making slimmer, large-sized, and lightweight devices and devices, and they are launching displays that include a curved portion in order to escape the flat display.

According to this trend, the glass material used as the display material is also required to be appropriately processed according to the display form. Japanese Unexamined Patent Publication No. 2003-160346 discloses a curved surface forming apparatus for a glass substrate, a Korean Patent Registration No. 1121449, a window glass banding forming method for a mobile terminal having a curved surface, a window glass banding forming apparatus therefor, and a Korean Patent Registration No. 1319409 A method and apparatus for manufacturing a curvature type touch screen glass and the like disclose bending processing of glass for application of a front protective sheet of a curved display.

However, conventional glass materials tend to be damaged in processing, leading to a low yield. On the other hand, there is a limit to pursue thinness and lightness due to their large specific gravity. Especially, when sophisticated processing is applied, it's difficult. Plastics have been actively studied as a substitute for glass in order to overcome the limitations of such glass materials. Particularly, a cover sheet for front protection, that is, a window sheet (window sheet) Is a rapidly growing market.

Polycarbonate (PC) resin is the most widely used plastics material to replace glass. PC is excellent in transparency, impact resistance, heat resistance, freedom of processing, and light weight, and can be used for automobile applications such as window cover, liquid crystal display cover for electric and electronic devices, window glass, sunroof, instrument cover, It is also applied to construction materials such as window glass. However, the surface hardness of the PC is low and the surface characteristics such as low reflectivity are limited, so that there are many restrictions to expand to the spreading stage.

Accordingly, research on plastic materials that can secure transparency, impact resistance, surface hardness, durability, and heat resistance has been continuously carried out. Until now, the laminated structure of PC and PMMA is the most stable plastic sheet It is being reported. However, in the case of the plastic material of the laminated structure, it can be said that the achievement of the physical properties has been attained to some extent, but when it is applied to the curved surface processing, the surface cracks and the cracks of the edge portions frequently occur. Particularly, in the case where hard coating treatment is applied to the surface, the yield of the curved surface treatment is remarkably reduced.

Prior art related to a curved plastic sheet has been disclosed in Korean Patent Registration No. 0723268, a curved surface forming apparatus and method of a flexible liquid crystal display, Korean Patent Laid-Open Publication No. 2015-0042123, a window member of a curved display device, A curved display device having the same, and a cover window of Korean Patent Laid-Open Publication No. 2014-0103547 and a display device having the same. However, these conventional techniques have a limitation in the form of a shape in which the entire sheet is curved at a specific curvature, or it is difficult to increase the hardness and scratch resistance due to the production of a sheet by an injection method, and a process for hard coating is separately performed There is a limitation that it should be done.

Accordingly, it is an object of the present invention to provide a method of manufacturing a curved transparent plastic sheet using a compression molding method other than an injection molding method, and to provide a curved transparent plastic sheet having excellent surface hardness and impact resistance, To provide a plastic sheet.

According to a first embodiment of the present invention, there is provided a method for manufacturing a semiconductor device, comprising the steps of: (S1) co-extruding polycarbonate (PC) and polymethylmethacrylate (PMMA) (S2) applying a hard coating composition to the base sheet obtained in the step (S1) with polymethylmethacrylate as an upper surface; (S3) drying and curing the hard coating composition applied in the step (S2) to produce a sheet having the hard coating layer formed thereon; (S4) a step of mounting the sheet obtained in the step (S3) to a lower mold of a compression molding machine provided with a mold having a curved surface portion and then preheating, and pressing the preheated sheet with an upper mold to form a sheet Wherein the transparent plastic sheet is a curved transparent plastic sheet.

The present invention also relates to a recording medium comprising a base sheet on which polycarbonate (PC) and polymethylmethacrylate (PMMA) are laminated, and a hard coat layer formed on the top surface of the substrate sheet of polymethylmethacrylate, A curved surface transparent plastic sheet having a surface hardness of 4H to 7H with a pencil hardness and a curved surface portion having a curvature radius of 8 to 50 mm is a second embodiment of the present invention, And can be produced by a production method.

Further, the present invention is a liquid crystal display device including a curved transparent plastic sheet according to the second embodiment as a cover sheet for front or rear protection.

The transparent plastic sheet of the present invention shows excellent surface hardness due to the hard coat layer formed with a thickness of 10 占 퐉 or more, but also the flexibility of the sheet is ensured, so that the impact strength and curved surface cracks may not occur. Further, by applying the compression molding method other than the conventional injection method, there is no fear that the hardness and scratch resistance of the sheet will be lowered.

1 is a process diagram showing an example of a manufacturing method of the present invention.
Fig. 2 is a photograph of a sample of a curved transparent plastic sheet having different curvature radii according to the present invention taken together with a curved display. Fig.

(S1) co-extruding polycarbonate (PC) and polymethylmethacrylate (PMMA) to produce a base sheet; (S2) applying a hard coating composition to the base sheet obtained in the step (S1) with polymethylmethacrylate as an upper surface; (S3) drying and curing the hard coating composition applied in the step (S2) to produce a sheet having the hard coating layer formed thereon; (S4) a step of mounting the sheet obtained in the step (S3) to a lower mold of a compression molding machine provided with a mold having a curved surface portion and then preheating, and pressing the preheated sheet with an upper mold to form a sheet The present invention provides a method of manufacturing a curved transparent plastic sheet.

The present invention also relates to a substrate sheet comprising a polycarbonate (PC) and polymethylmethacrylate (PMMA) laminated thereon; And a hard coating layer formed on the top surface of the substrate sheet of polymethylmethacrylate, wherein the surface hardness measured on the surface of the coating layer is 4H to 7H in terms of pencil hardness and the curved surface has a curved surface radius of 5 to 200 mm A plastic sheet is provided. The plastic sheet of the present invention may be 'transparent' having a light transmittance of 89% or more as measured according to ASTM D1003, and preferably has a transmittance of 89 to 94%. Accordingly, the present invention can provide a liquid crystal display device including the curved transparent plastic sheet as a cover sheet.

Hereinafter, the present invention will be described more specifically.

( S1 ) Step: Substrate sheet production step

The step (S1) of the present invention is a step of producing a base sheet having a structure in which polycarbonate (hereinafter referred to as PC) and polymethyl methacrylate (hereinafter referred to as PMMA) are laminated, and the base sheet is produced by co- . The extruder for co-extrusion is constituted by a main extruder for extruding PC and a sub-extruder for extruding PMMA. However, since the thermal characteristics of PC and PMMA are different, it is preferable to control the temperature condition of the main extruder at 270 to 290 ° C And the temperature condition of the sub-extruder is controlled to 230 to 250 ° C. The extruder may preferably be provided with a polymer filter to remove foreign substances in the resin, but is not limited thereto.

Examples of the method of extruding the injected resin include a multi-manifold method in which different resins are formed into a sheet in the die, or a multi-manifold method in which resin is introduced into a sheet molding die such as a T- A known method such as a method can be used. At this time, the temperature of the die is 250 to 320 占 폚, preferably 270 to 300 占 폚, and the temperature of the forming roll is usually 100 to 140 占 폚, preferably 110 to 130 占 폚, .

In this case, the thickness of each layer can be controlled by controlling the speeds of the main extruder and the sub-extruder. According to a preferred embodiment of the present invention, pneumatic shipment is performed so that the thickness ratio of the PC layer and the PMMA layer is 95 to 60: . When the thickness of the PMMA is less than 5%, the effect of improving the surface hardness is insignificant, and when the thickness exceeds 40%, the dimensional change of the plastic sheet may occur.

In the present invention, the PC layer serves to secure the impact strength of the sheet. In this case, the polycarbonate resin may be, for example, an aromatic dihydroxy compound alone or an aromatic dihydroxy compound and a small amount of a polyhydroxy compound and a phosgene Or may be a linear or branched polycarbonate resin produced by an ester exchange reaction between an aromatic dihydroxy compound and a diester of carbonic acid.

The molecular weight of the polycarbonate resin is not particularly limited as long as the sheet can be produced by ordinary extrusion molding, but it is preferably 10,000 to 200,000, more preferably 40,000 to 80,000. The polycarbonate resin may have a glass transition temperature of 140 to 150 ° C and a refractive index of 1.55 to 1.60. The polycarbonate resin may contain various commonly used additives. Examples of possible additives include antioxidants, antistatic agents, ultraviolet absorbers, light diffusing agents, flame retardants, release agents, lubricants, antistatic agents and the like, but are not limited thereto .

In the present invention, the PMMA layer plays a role of securing the surface hardness. Particularly, in the present invention, the PMMA layer preferably contains PMMA having a glass transition temperature of 120 to 135 ° C in an amount of 50 wt% It is preferable that the content ratio is included. In the present invention, 'PMMA' having a glass transition temperature of 120 to 135 ° C. in the present invention may mean heat-resistant PMMA, and more specifically, styrene methyl methacrylate maleic anhydride copolymer containing 15 to 70% of styrene, 25 to 80% of methyl methacrylate, And 5 to 50% of Maleic anhydride.

The heat-resistant PMMA is distinguished from a conventional PMMA resin (hereinafter referred to as general PMMA) having a glass transition temperature of 100 to 110 占 폚, and has a water absorption rate of 0.15 to 0.2% based on a temperature of 35 占 폚 and a relative humidity of 97% And the dimensional strain may be 0.2 to 0.25% based on a temperature of 65 캜 and a relative humidity condition of 90%. When the heat resistant PMMA having a glass transition temperature of 120 to 135 DEG C as described in the present invention is used, the deformation of the sheet can be minimized as compared with the case of using general PMMA which is highly affected by moisture, and consequently the reliability of the final sheet can be remarkably increased .

The heat-resistant PMMA having a glass transition temperature of 120 to 135 占 폚 has a surface energy as high as 29 nN / m and thus exhibits excellent adhesion with the hard coating liquid as compared with general PMMA, and can exhibit excellent adhesion penetration. That is, the adhesion with the coating layer can be further improved, and the compatibility with the coating layer is excellent, so that surface cracking and edge cracking can be remarkably reduced during processing. However, in order to secure the reliability and adhesion as described above, it is preferable that modified PMMA having a glass transition temperature of 120 to 135 ° C is contained at a content ratio of 50% by weight or more based on the total weight of the resin of the PMMA layer.

( S2 ) ~ ( S3 ) step: hard  Coating layer formation step

The step (S2) of the present invention is a step of applying a hard coating composition using the PMMA of the base sheet prepared in the step (S1) as an upper surface, wherein the hard coating composition of the present invention comprises an acrylic coating composition, A urethane-based coating composition, a siloxane-based coating composition, and a mixture thereof.

Generally, since the hardness of the plastic sheet by PC is very weak, the PMMA is laminated to secure the surface hardness to 2H. However, when a hard coating layer is further formed on the plastic sheet, the measurement standard of ASTM D3363, The surface hardness (pencil hardness) of the curved transparent plastic sheet can be further improved to 4H to 7H. Also, according to ASTM D256, the impact strength is 20 J / cm ² and the impact resistance is excellent due to the PC and PMMA laminated structure.

In the present invention, the hard coating composition may be an acrylic coating composition obtained by polymerizing a monofunctional or polyfunctional acrylate alone or in combination, or an acrylic coating composition containing an alicyclic epoxy group in a molecular structure and having a weight average molecular weight of 1000 to 15000 and a polydispersity index It is more preferable to apply a siloxane-based coating composition containing a siloxane resin having a PDI of 5.0 to 1.2.

Particularly, when a hard coating layer is formed of a siloxane resin-based resin composition containing a siloxane resin, the siloxane chain has a strong inorganic property and at the same time has an alicyclic structure at the end, securing excellent hardness and ensuring flexibility Accordingly, the processability can be particularly excellent, and therefore, it may be most preferable in the present invention. Here, the weight average molecular weight may be a value measured by a conventional method using GPC (Gel Permeation Chromatography), and PDI is a value obtained by dividing the measured weight average molecular weight by a number average molecular weight (which can also be measured by GPC) Can be calculated separately .

More specifically, the siloxane resin may be an alkoxysilane containing an alicyclic epoxy group and an alkoxy group represented by the following general formula (1); Or an alkoxysilane containing an alicyclic epoxy group and an alkoxy group represented by the following formula (1) and an alkoxysilane compound represented by the following formula (2). The epoxy equivalent is 0.35 to 0.6 mol / 100 g, which is a relatively high epoxy equivalent To increase the degree of crosslinking so that the cured film is formed densely.

???????? R ¹ _n -Si- (OR ² ) _4-n ?????

???????? R ³ _m -Si- (OR ⁴ ) _4-m ?????

Wherein R ¹ is a linear or branched C1 to C6 alkyl group containing an alicyclic epoxy group and the cycloaliphatic epoxy group has a structure having an epoxy group as a C3 to C6 cycloalkyl group and R ₂ is linear or branched And R ³ is a C1 to C20 alkyl group, a C3 to C8 cycloalkyl group, a C2 to C20 alkenyl group, a C2 to C20 alkynyl group, a C6 to C20 aryl group, an acrylic group, a methacrylic group, a halogen group R ⁴ is a linear or branched C 1 to C 7 alkyl group, n is an integer of 1 to 3, n is an integer of 1 to 5, n is an integer of 1 to 5, Is an integer of 1 to 3, and m is an integer of 0 to 3.

In the present invention, the hard coating composition may further include at least one additive selected from the group consisting of reactive monomers, crosslinking agents, organic solvents, photoinitiators, thermal initiators, antioxidants, leveling agents and coating aids, However, the reactive monomers may be monomers having an alicyclic epoxy group or oxetane groups, and the crosslinking agent may be an acid anhydride monomer.

According to a preferred embodiment of the present invention, the hard coating composition may be applied through a slot die coater for uniformity of thickness, and may be formed not only on the top of the PMMA layer, In order to minimize warpage, it may be additionally formed at the bottom of the PC layer, but is not necessarily limited thereto. However, it is preferable that the thickness of the coating layer is controlled to 10 to 100 mu m so that the surface hardness can be improved without increasing the thickness of the entire sheet. Thus, the thickness of the entire sheet can be maintained at 0.5 to 1.0 mm .

After the hard coating composition is applied to the base sheet through the step (S2) of the present invention, the hard coating composition is dried at a temperature of 50 to 85 캜 and dried at a temperature of 600 to 4000 mJ / cm ² A step of irradiating a light amount of UV to cure the dried hard coating composition may be performed.

When the thermal drying temperature of the coating film is less than 50 캜, organic solvent remains in the coating film, and when it is more than 85 캜, thermal damage to the substrate may occur. In addition, the radiation-curing is at 200 ~ 380nm wavelength ranges from 5 to be performed 30 seconds, and because hardening is not sufficiently achieved when the amount of light is 600 mJ / cm ² below is not easy, the hardness obtained, 4000 mJ / cm ² greater than one The adhesive force between the base material and the coating layer may be lowered to cause cracking during curved surface molding or curling due to shrinkage of the coating layer.

( S4 ) Step: forming step of sheet

Following the step (S3), the present invention may include a step (S4) of molding a sheet on which the coating layer is formed through a compression molding machine provided with a mold having a curved surface portion having a radius of curvature of 5 to 200 mm. When the radius of curvature is less than 5 mm, the PMMA layer can easily break, and when the radius of curvature exceeds 200 mm, there is a problem that it is too gentle to show features as a molded product.

In the present invention, when the sheet is formed through the compression molding machine, it is preferable that the sheet is first attached to the lower part of the mold of the compression molding machine and it is preferable to preheat the sheet at a temperature of 90 to 130 ° C. If the sheet is not sufficiently preheated, cracking of the surface coating layer may occur when bent, and if it is excessively preheated, surface characteristics are not uniform due to softening of the coating layer and the PMMA layer. However, since the sheet of the present invention has excellent bending workability toward the coating layer and bending workability in the direction opposite to the coating layer direction, there is an advantage that the sheet is not limited in the mounting direction when the sheet is mounted on the lower mold.

After the sheet is sufficiently preheated, the sheet is molded by applying a pressure of 5 to 20 kg / cm ² to the sheet with the upper mold. In this case, the molding may preferably be performed at a temperature of 100 to 120 DEG C for 30 seconds to 5 minutes. If the pressure during molding is less than 5 kg / cm ² , the desired shape can not be sufficiently formed. If the pressure exceeds 20 kg / cm ² , the PMMA layer on the surface of the base layer may be cracked. If the time and temperature do not fall within the above range, it is preferable to take care that the surface layer and the coating layer of the base layer may be broken when the time exceeds the above range.

Further, the present invention may further include a step of cooling the sheet formed at the step (S4) at 40 to 70 캜 as a subsequent step of the step (S4), and if necessary, a printing patterning method A certain pattern may be formed on the sheet surface. Generally, when a molded sheet is cooled, a stress is generated in the sheet due to the viscoelasticity of the polymer, thereby causing a springback phenomenon in which the formed sheet tends to return to the original shape by a certain amount. However, the curved transparent plastic sheet of the present invention hardly exhibits post-warpage even by the above-mentioned cooling, so that the shape stability can be very excellent.

As a result, the transparent plastic sheet of the present invention can provide excellent impact resistance, surface hardness and workability in spite of forming a coating layer of a thick film, and can be easily applied as a front cover sheet of a liquid crystal display device.

Example

Hereinafter, the present invention will be described in more detail with reference to Examples. These examples are for the purpose of illustrating the present invention more specifically, and the present invention is not limited thereto.

Example

A polycarbonate (LG Chem) resin having a glass transition temperature of 147 캜 and Heat resistant PMMA resin (15 to 70% of styrene, 25 to 80% of methyl methacrylate, and maleic (meth) acrylate having a glass transition temperature of 129 占 폚, a water absorption rate of 35 占 폚 / 97% and a dimensional change rate of 0.21% at 60 占 폚 / anhydride 5 to 50% copolymerization) were prepared. The prepared PC resin and heat-resistant PMMA resin were mixed with a main extruder having a barrel diameter of 150 mm, a screw L / D of 35 and a cylinder temperature of 270 캜, and a barrel having a diameter of 45 mm, a screw L / D of 35 and a cylinder temperature of 245 캜 Extruded into a set sub-extruder to simultaneously melt-extrude the two resins.

The temperature in the die pads was then set to 270 and 245 DEG C respectively and the laminated and integrated resin in the die was passed through three polishing rolls of mirror-finished horizontal arrangement. At this time, the temperature of the first roll was set to 100 ° C, the temperature of the second roll was set to 130 ° C and the temperature of the third roll was set to 120 ° C. The number of revolutions of the main extruder (support layer forming extruder) and the sub- A plastic sheet (thickness: 1 mm) was prepared so that the discharge amount ratio was set to be Main / Sub = 85/15, so that the PC layer was 0.85 mm and the PMMA layer was 0.15 mm thick.

On the other hand, 10 parts by weight of a monomer having an oxetane group and 1 part by weight of a photoinitiator were mixed with 100 parts by weight of a siloxane resin (weight average molecular weight: 1000 to 15000, PDI: 5.0 to 1.2) % To prepare a coating solution (siloxane resin composition). The thus prepared coating solution is slit-die-coated on the PMMA layer of the plastic sheet to a thickness of 10 to 100 탆, dried in a drying oven at 70 to 80 캜 for 5 to 15 minutes and then dried at 600 to 4000 mJ / cm ² And then cured with a UV-B lamp at a light quantity condition to finally produce a transparent plastic sheet.

Subsequently, the sheet thus prepared was mounted on a compression molding machine equipped with a mold having a curved surface portion having a radius of curvature of 8R (8 mm) on a radial basis, preheated at 120 DEG C for 30 seconds at 5 minutes, cm < ² > to form a sheet. The temperature during molding was controlled at 110 ° C and compressed for 1 minute. After molding was completed, it was cooled at 80 ° C.

Comparative Example  One

Comparative Example 1 was prepared in the same manner as in the above Example except that the sheet was preheated to less than 30 seconds and then molded.

Comparative Example  2

Comparative Example 2 was prepared in the same manner as in the above example, except that the temperature of the compression molding machine was controlled to be less than 80 캜 during molding.

Comparative Example  3

Comparative Example 3 was produced in the same manner as in the above example, except that the compression molding time during molding was controlled to be less than 30 seconds.

Then, the physical properties of the above Examples and Comparative Examples 1 to 3 were evaluated as follows, and the results are shown in Table 1 below.

Measurement example

1) Haze and transmittance measurement: Measured haze and transmittance were respectively measured according to ASTM D1003 standard.

2) Measurement of YI value: After the UV-B lamp was mounted on the QUV instrument, the sample was dropped by 60 cm from the lamp, and the YI value was measured based on the ASTM E-313 calculation method.

3) Measurement of ball drop characteristics: According to ASTM D5628-10, 130g of ball is vertically dropped from 10cm to 100cm distance to check the point at which scratches occur, (Typically, the set maker specifies a specification that will not break at a height of 20 cm or more).

4) Measurement of surface hardness (pencil hardness): The surface hardness was measured on the basis of an electric type 1 kg load using a pencil (Mitsubishi 6B to 9H) manufactured by Mitsubishi in accordance with ASTM D3363 standard.

5) Measurement of Flexural Modulus: A 3-point bending test was performed according to ASTM D790 standard.

6) Notched Impact Strength Measurement: Notch was made in each sample and measured according to ASTM D256 at 23 ° C.

Metrics Example Comparative Example 1 Comparative Example 2 Comparative Example 3 Haze (%) 0.1 0.1 0.1 0.1 Transmittance (%) 92 92 92 92 YI 0.56 0.56 0.25 0.42 Ball drop characteristic (20cm) No scratches No scratches No scratches No scratches Surface hardness (pencil hardness) 4 ~ 9H 4 ~ 9H 4 ~ 9H 4 ~ 9H Flexural modulus (GPa) 2.1 2.2 2.2 2.2 Impact strength (J / cm ² ) 40 42 41 40 Curve after cooling to target 10R (10mm) 9 11 20 16 After forming the coating layer
Broken Not broken fracture fracture Not broken

As can be seen from Table 1, when the time and temperature conditions were appropriate for preheating and molding as in the examples, the coating layer was not cracked and the workability was excellent. However, as in Comparative Example 1, In the case of preheating, only the surface is preheated and it is difficult to process because it is not bent as a whole when it is bent. In addition, when molding at a temperature lower than 80 캜 as in Comparative Example 2, the surface coating layer was cracked due to unreasonable bending due to insufficient deformation, and the compression time was less than 30 seconds It has been found that it is difficult to maintain the desired bending while the formed sheet is cooled and restored again.

Claims (17)

(S1) co-extruding polycarbonate (PC) and polymethylmethacrylate (PMMA) to produce a base sheet;
(S2) applying a hard coating composition to the base sheet obtained in the step (S1) with polymethylmethacrylate as an upper surface;
(S3) drying and curing the hard coating composition applied in the step (S2) to produce a sheet having the hard coating layer formed thereon;
(S4) a step of attaching the sheet obtained in the step (S3) to a lower mold of a compression molding machine provided with a mold having a curved portion and then preheating, and pressing the preheated sheet with an upper mold to form a sheet Method of manufacturing a curved transparent plastic sheet.
The method according to claim 1, wherein the co-extrusion ratio of polycarbonate to polymethyl methacrylate is 95 to 60: 5 to 40 in step (S1).
The method according to claim 1, wherein the polymethylmethacrylate (PMMA) in step (S1) comprises polymethylmethacrylate having a glass temperature of 120 to 135 DEG C in an amount of 50 wt% or more based on the total weight of the resin Method of manufacturing a curved transparent plastic sheet.
The method according to claim 1, wherein the hard coating composition is selected from the group consisting of an acrylic coating composition, an epoxy coating composition, a urethane coating composition, and a siloxane coating composition.
The method according to claim 4, wherein the hard coating composition is coated through a slot die coater at a thickness of 10 to 100 탆.
The method according to claim 1, wherein the drying in step (S3) is performed at a temperature of 50 to 85 ° C.
The method according to claim 1, wherein the curing in step (S3) is performed by irradiating UV with a light quantity of 600 to 4000 mJ / cm ² .
The method according to claim 1, wherein the compression molding machine in step (S4) comprises a mold having a curved surface portion having a radius of curvature of 5 to 200 mm.
The method of claim 1, wherein the (S4) in step the sheet 90 to be preheated at a temperature of 130 ℃, 5 to 20 are compressed by the upper surface of the mold controlled at a pressure of kg / cm ^2, characterized in that the molded curved A method of manufacturing a transparent plastic sheet.
The method according to claim 1, wherein the molding in step (S4) is performed at a temperature of 100 to 120 ° C for 30 seconds to 5 minutes.
The method according to claim 1, further comprising, as a subsequent step of the step (S4), cooling the sheet formed at the step (S4) at 40 to 70 占 폚.
(PC) and polymethylmethacrylate (PMMA), and a hard coating layer formed on the top surface of the substrate sheet of polymethylmethacrylate
Wherein the surface hardness of the hard coating layer measured in terms of pencil hardness is 4H to 7H and the curvature radius is 5 to 200 mm.
[12] The method of claim 12, wherein the polymethylmethacrylate comprises 50% or more by weight of heat resistant polymethylmethacrylate (PMMA) having a glass transition temperature of 120 to 135 [deg.] C,
Wherein the hard coating layer is a cured product selected from the group consisting of an acrylic hard coating composition, a urethane hard coating composition and a siloxane hard coating composition.
The transparent plastic sheet according to claim 12, wherein the transparent plastic sheet has an impact strength of 20 to 50 J / cm ² as measured at the top of the hard coating layer according to ASTM D256.
The transparent plastic sheet according to claim 12, wherein the transparent plastic sheet has a transmittance of 89 to 94% as measured by ASTM D1003 as a whole.
The transparent plastic sheet according to claim 12, wherein the transparent plastic sheet is manufactured by the method according to any one of claims 1 to 11.
A liquid crystal display device comprising the transparent plastic sheet according to any one of claims 12 to 15.

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