阅读说明：本技术 挤出树脂板及其制造方法 (Extruded resin sheet and method for producing same ) 是由 船崎一男 于 2018-04-26 设计创作，主要内容包括：本发明提供适合作为液晶显示器等的保护板的挤出树脂板的制造方法。将在聚碳酸酯含有层的至少单面上层叠有甲基丙烯酸类树脂含有层的层叠体以熔融状态从T型模头共挤出,使用彼此相邻的三个以上的冷却辊进行冷却,将所得到的挤出树脂板利用引离辊引离。使被夹入第二个冷却辊与第三个冷却辊之间时的层叠体的整体温度(TX)为相对于聚碳酸酯含有层的玻璃化转变温度(Tg(PC))+10℃以上,使从最后的冷却辊剥离的位置处的层叠体的整体温度(TT)为相对于Tg(PC)-2℃～+19℃的范围。使引离辊的圆周速度(V4)与第二个冷却辊的圆周速度(V2)的圆周速度比(V4/V2)为0.98以上且小于1.0。(the invention provides a method for producing an extruded resin sheet suitable for a protective sheet of a liquid crystal display or the like. The method for producing the polycarbonate resin sheet includes the steps of co-extruding a laminate in which a methacrylic resin-containing layer is laminated on at least one surface of a polycarbonate-containing layer from a T-die in a molten state, cooling the laminate using three or more cooling rolls adjacent to each other, and separating the resulting extruded resin sheet by a separation roll. The Temperature (TX) of the whole laminate when it is sandwiched between the second cooling roll and the third cooling roll is set to a glass transition temperature (Tg (PC)) +10 ℃ or higher with respect to the polycarbonate-containing layer, and The Temperature (TT) of the whole laminate at the position where it is peeled off from the last cooling roll is set to a range of-2 ℃ to +19 ℃ with respect to Tg (PC). The peripheral speed ratio (V4/V2) of the peripheral speed (V4) of the take-off roller to the peripheral speed (V2) of the second cooling roller is 0.98 or more and less than 1.0.)

1. A method for producing an extruded resin sheet, which comprises laminating a layer containing a methacrylic resin on at least one surface of a layer containing a polycarbonate,

Comprising the following steps (X):

Co-extruding a thermoplastic resin laminate in which the methacrylic resin-containing layer is laminated on at least one surface of the polycarbonate-containing layer from a T-die in a molten state,

Cooling the thermoplastic resin laminate in a molten state by repeating the operation of sandwiching the thermoplastic resin laminate in a molten state between an nth (where n.gtoreq.1) cooling roll and an n +1 th cooling roll and winding the thermoplastic resin laminate around the n +1 th cooling roll from n ≧ 1 by using three or more cooling rolls adjacent to each other,

The extruded resin sheet obtained after cooling is separated by a separation roller,

The overall Temperature (TX) of the thermoplastic resin laminate when sandwiched between the second cooling roll and the third cooling roll is set to +10 ℃ or higher relative to the glass transition temperature of the polycarbonate-containing layer,

The Temperature (TT) of the thermoplastic resin laminate at the position of peeling from the last cooling roll is set to a range of-2 ℃ to +19 ℃ relative to the glass transition temperature of the polycarbonate-containing layer,

the peripheral speed ratio (V4/V2) of the peripheral speed (V4) of the leading-off roller to the peripheral speed (V2) of the second cooling roller is 0.98 or more and less than 1.0.

2. The method of manufacturing an extruded resin sheet according to claim 1,

The methacrylic resin-containing layer has a glass transition temperature of 110 ℃ or higher,

The ratio ((S2-S1)/S1) of the difference (S2-S1) between the linear expansion coefficient (S1) of the polycarbonate-containing layer and the linear expansion coefficient (S2) of the methacrylic resin-containing layer and the linear expansion coefficient (S1) of the polycarbonate-containing layer is-10% to + 10%.

3. The method for producing an extruded resin sheet according to claim 1 or 2, wherein the methacrylic resin contains 40 to 80 mass% of a structural unit derived from methyl methacrylate and 60 to 20 mass% of a structural unit derived from alicyclic hydrocarbon methacrylate.

4. The method for producing an extruded resin sheet according to claim 3, wherein the alicyclic hydrocarbon methacrylate is polycyclic aliphatic hydrocarbon methacrylate.

5. The method for producing an extruded resin sheet according to claim 1 or 2, wherein the methacrylic resin-containing layer contains 5 to 80 mass% of a methacrylic resin and 95 to 20 mass% of a copolymer containing a structural unit derived from an aromatic vinyl compound and a structural unit derived from maleic anhydride.

6. The method for producing an extruded resin sheet according to claim 5, wherein the copolymer contains 50 to 84 mass% of the structural unit derived from an aromatic vinyl compound, 15 to 49 mass% of the structural unit derived from maleic anhydride, and 1 to 35 mass% of the structural unit derived from a methacrylic acid ester.

7. the method of producing an extruded resin sheet according to claim 6, wherein the methacrylate is methyl methacrylate.

8. The method of producing an extruded resin sheet according to any one of claims 1 to 7,

further comprising a step (Y) of heating the extruded resin sheet at a temperature of 65 to 110 ℃ for 1 to 30 hours after the step (X),

In the extruded resin sheet before heating, when an axis parallel to the extrusion direction is set to 0 DEG, the absolute value of the angle of a slow axis or a fast axis of retardation in a plane is 5-45 DEG,

The retardation value in the plane of at least a part of the width direction of the extruded resin sheet is 50 to 330nm before and after heating,

The rate of decrease in the retardation value of the extruded resin sheet after heating is less than 30% relative to before heating.

9. An extruded resin sheet comprising a polycarbonate-containing layer and a methacrylic resin-containing layer laminated on at least one surface of the polycarbonate-containing layer,

The absolute value of the angle of the slow axis or the fast axis of retardation in a plane when the axis parallel to the extrusion direction is set to 0 DEG is 5 to 45 DEG,

The methacrylic resin-containing layer has a glass transition temperature of 110 ℃ or higher,

when heated at a constant temperature of 75 to 100 ℃ for 5 hours, the retardation value in a plane of at least a part of the width direction is 50 to 330nm before and after the heating,

The rate of decrease of the retardation value after heating is less than 30% relative to before heating,

the ratio ((S2-S1)/S1) of the difference (S2-S1) between the linear expansion coefficient (S1) of the polycarbonate-containing layer and the linear expansion coefficient (S2) of the methacrylic resin-containing layer and the linear expansion coefficient (S1) of the polycarbonate-containing layer is-10% to + 10%.

10. The extruded resin sheet according to claim 9,

When the extruded resin sheet is heated at 75 ℃ or 100 ℃ for 5 hours, the in-plane retardation value of at least a part of the width direction is 50 to 330nm both before and after heating,

The rate of decrease of the retardation value after heating is less than 30% relative to before heating.

11. The extruded resin sheet according to claim 9 or 10, wherein the in-plane retardation value of at least a part of the width direction is 80 to 250nm both before and after heating.

12. The extruded resin sheet according to any one of claims 9 to 11, wherein the retardation value after heating is decreased by less than 15% with respect to that before heating.

13. The extruded resin sheet according to any one of claims 9 to 12, further comprising a scratch-resistant layer on at least one surface thereof.

Technical Field

The present invention relates to a method for producing an extruded resin sheet and an extruded resin sheet.

background

Flat panel displays such as liquid crystal displays and touch panel displays that are a combination of the flat panel display and a touch panel (also referred to as a touch screen) are used in ATMs of financial institutions such as banks; a vending machine; mobile phones (including smart phones), portable information terminals (PDAs) such as tablet personal computers, digital audio players, portable game machines, copying machines, facsimile machines, and digital information devices such as car navigation systems.

In order to prevent scratches on the surface, a transparent protective plate is provided on the surface of a liquid crystal display, a touch panel, or the like. Conventionally, tempered glass has been mainly used as a protective plate, but development of a transparent resin plate has been advanced from the viewpoint of workability and weight reduction. The protective plate is required to have functions such as gloss, scratch resistance, and impact resistance.

As a protective plate made of a transparent resin, a resin plate including a polycarbonate layer excellent in impact resistance and a methacrylic resin layer excellent in gloss and scratch resistance has been studied. The resin sheet is preferably produced by coextrusion molding. In this case, due to the difference in the characteristics of the two resins, a deformation stress may remain in the resulting resin sheet. The deformation stress remaining in the resin board is referred to as "residual stress", and the resin board having the residual stress may be warped or the like due to thermal change or the like.

As a method for reducing residual stress in a resin sheet and suppressing the occurrence of warpage, patent document 1 discloses a method for adjusting the rotation speed of a cooling roll used for extrusion molding (claim 1). Patent document 2 discloses a method in which a methacrylic resin laminated with a polycarbonate is obtained by copolymerizing a methacrylic acid ester such as Methyl Methacrylate (MMA) with an aromatic vinyl monomer such as styrene and then hydrogenating the aromatic double bonds (claim 2).

in order to solve the above problems, studies have been made on improvement of heat resistance and moisture resistance of methacrylic resins. For example, patent document 3 discloses a method in which a resin having a unit selected from an MMA unit, a Methacrylic Acid (MA) unit, an Acrylic Acid (AA) unit, a maleic anhydride unit, an N-substituted or unsubstituted maleimide unit, a glutaric anhydride structural unit, and a glutarimide structural unit and having a glass transition temperature (Tg) of 110 ℃ or higher is used as a methacrylic resin laminated with a polycarbonate (claim 1).

Further, patent document 4 discloses the following method: in a decorative sheet obtained by laminating two resin sheets with at least one pattern layer interposed therebetween, the difference in linear expansion coefficient (also referred to as a linear expansion coefficient) between the two resin sheets is reduced (claim 1).

A cured coating having low reflectivity for improving scratch resistance (hard coat property) and/or visibility can be formed on at least one surface of the protective plate (claims 1 and 2 of patent document 5, claim 1 of patent document 6, and the like).

A protective plate for a liquid crystal display through which a viewer views a screen of the liquid crystal display is provided on the front surface side (viewer side) of the liquid crystal display. Here, since the protective plate does not substantially change the polarization of light emitted from the liquid crystal display, when the screen is viewed through a polarizing filter such as a polarizing sunglass, the screen may become dark depending on an angle formed by the polarization axis of the emitted light and the transmission axis of the polarizing filter, and the visibility of the image may be reduced. Therefore, studies have been made on a protective plate for a liquid crystal display that can suppress a decrease in image visibility when a screen of the liquid crystal display is viewed through a polarizing filter. For example, patent document 7 discloses a protective plate for a liquid crystal display, which is composed of a scratch-resistant resin plate having a cured coating film formed on at least one surface of a resin substrate, and has an in-plane retardation value (Re) of 85 to 300nm (claim 1).

In general, the extruded resin sheet is subjected to stress during molding, and the molecules are oriented, thereby causing retardation in some cases (see paragraph 0034 of patent document 8). In an extruded resin sheet including a plurality of resin layers, the degree of residual stress may vary among the resin layers. In addition, in the molding of the extruded resin sheet, when the extruded resin sheet is separated from the last cooling roll, a streak-like defect (so-called chatter marks) may be generated on the surface of the extruded resin sheet, and the surface properties may be degraded. By adjusting the manufacturing conditions such as the rotational speed of the cooling roll and the take-off roll used for extrusion molding, stress and chatter marks generated during molding can be reduced.

For example, in order to reduce stress generated during molding of an extruded resin sheet and suppress a decrease in Re value, patent documents 8 and 9 disclose a method for producing an extruded resin sheet in which, when an extruded resin sheet having a methacrylic resin layer laminated on at least one surface of a polycarbonate layer is co-extruded and molded, production conditions such as a relationship between peripheral speeds of a plurality of cooling rolls and a take-off roll and a temperature of the entire resin at a time of peeling from the last cooling roll are optimized (claim 1 of patent document 8, claims 3 and 4 of patent document 9, and the like).

Disclosure of Invention

Problems to be solved by the invention

In the step of forming a cured coating having abrasion resistance (hard coat property) and/or low reflectance on the surface of the resin plate, the resin plate may be heated to a temperature of about 100 ℃. For example, heat is required for curing a thermosetting coating material, and a photocurable coating material is heated when irradiated with light. When the coating material contains a solvent, heating may be performed for drying the solvent.

In addition, a protective plate used for a liquid crystal display mounted in a vehicle-mounted display device such as a car navigation system or a mobile phone (including a smartphone) may be used in a high-temperature environment such as summer sunshine.

When the resin plate is exposed to high temperatures in the production process or in the use environment, the Re value may be lowered by heat and may be out of the desired range. Preferably, the thermal change in Re value is small.

In patent document 7, the visibility is evaluated in a configuration in which the transmission axis of the polarizing plate of the liquid crystal display and the extrusion direction of the resin plate form an angle of 45 ° (paragraph 0072). The direction of the transmission axis of the polarizing plate of the liquid crystal display is a 45 ° oblique or horizontal direction with respect to the viewing screen, and the extrusion direction of the resin sheet is sometimes a horizontal or vertical direction from the viewpoint of productivity and effective utilization of the resin sheet. In this case, the transmission axis of the polarizing plate of the liquid crystal display is parallel or perpendicular to the slow axis or the fast axis of the plane-average retardation of the resin plate. In the case of such a relationship, particularly when a screen is viewed through a polarizing filter such as a polarizing sunglass, visibility may be deteriorated regardless of the Re value. It should be noted that this problem was first discovered by the present inventors and has not been solved so far.

The present invention has been made in view of the above circumstances, and an object thereof is to provide an extruded resin sheet which is less likely to cause warpage due to thermal changes, has an in-plane retardation value (Re) and an in-plane retardation axis direction within a preferable range, and has good surface properties, and a method for producing the same.

Means for solving the problems

The present invention provides the following extruded resin sheets [1] to [13] and a method for producing the same.

[1] A method for producing an extruded resin sheet, which comprises laminating a layer containing a methacrylic resin on at least one surface of a layer containing a polycarbonate,

comprising the following steps (X):

Co-extruding a thermoplastic resin laminate in which the methacrylic resin-containing layer is laminated on at least one surface of the polycarbonate-containing layer from a T-die in a molten state,

Cooling the thermoplastic resin laminate in a molten state by repeating the operation of sandwiching the thermoplastic resin laminate in a molten state between an nth (where n.gtoreq.1) cooling roll and an n +1 th cooling roll and winding the thermoplastic resin laminate around the n +1 th cooling roll from n ≧ 1 by using three or more cooling rolls adjacent to each other,

The extruded resin sheet obtained after cooling is separated by a separating roller,

The Temperature (TX) of the thermoplastic resin laminate as a whole when the laminate is sandwiched between the second cooling roll and the third cooling roll is set to +10 ℃ or higher relative to the glass transition temperature of the polycarbonate-containing layer,

The Temperature (TT) of the thermoplastic resin laminate at the position of peeling from the last cooling roll is set to a range of-2 ℃ to +19 ℃ relative to the glass transition temperature of the polycarbonate-containing layer,

The peripheral speed ratio (V4/V2) of the peripheral speed (V4) of the take-off roller to the peripheral speed (V2) of the second cooling roller is 0.98 or more and less than 1.0.

[2] The method for producing an extruded resin sheet according to [1], wherein,

The glass transition temperature of the methacrylic resin-containing layer is 110 ℃ or higher,

The ratio ((S2-S1)/S1) of the difference (S2-S1) between the linear expansion coefficient (S1) of the polycarbonate-containing layer and the linear expansion coefficient (S2) of the methacrylic resin-containing layer and the linear expansion coefficient (S1) of the polycarbonate-containing layer is-10% to + 10%.

[3] The process for producing an extruded resin sheet according to [1] or [2], wherein the methacrylic resin contains 40 to 80 mass% of a structural unit derived from methyl methacrylate and 60 to 20 mass% of a structural unit derived from an alicyclic hydrocarbon methacrylate.

[4] The method for producing an extruded resin sheet according to [3], wherein the alicyclic hydrocarbon methacrylate is a polycyclic aliphatic hydrocarbon methacrylate.

[5] The method for producing an extruded resin sheet according to [1] or [2], wherein the layer containing a methacrylic resin contains 5 to 80 mass% of the methacrylic resin and 95 to 20 mass% of a copolymer containing a structural unit derived from an aromatic vinyl compound and a structural unit derived from maleic anhydride.

[6] the process for producing an extruded resin sheet according to [5], wherein the copolymer contains 50 to 84 mass% of the structural unit derived from an aromatic vinyl compound, 15 to 49 mass% of the structural unit derived from maleic anhydride, and 1 to 35 mass% of the structural unit derived from a methacrylic acid ester.

[7] The method for producing an extruded resin sheet according to [6], wherein the methacrylate is methyl methacrylate.

[8] The method for producing an extruded resin sheet according to any one of [1] to [7], wherein,

Further comprising a step (Y) of heating the extruded resin sheet at a temperature of 65 to 110 ℃ for 1 to 30 hours after the step (X),

In the extruded resin sheet before heating, when an axis parallel to the extrusion direction is set to 0 DEG, the absolute value of the angle of the slow axis or the fast axis of retardation in a plane is 5-45 DEG,

The retardation value in the plane of at least a part of the width direction of the extruded resin sheet is 50 to 330nm before and after heating,

the rate of decrease in the retardation value of the extruded resin sheet after heating is less than 30% relative to that before heating.

[9] An extruded resin sheet comprising a polycarbonate-containing layer and a methacrylic resin-containing layer laminated on at least one surface of the polycarbonate-containing layer,

The absolute value of the angle of the slow axis or the fast axis of retardation in a plane when the axis parallel to the extrusion direction is set to 0 DEG is 5 to 45 DEG,

the glass transition temperature of the methacrylic resin-containing layer is 110 ℃ or higher,

when heated at a constant temperature of 75 to 100 ℃ for 5 hours, the retardation value in a plane of at least a part of the width direction is 50 to 330nm before and after the heating,

The rate of decrease in the retardation value after heating is less than 30% relative to that before heating,

The ratio ((S2-S1)/S1) of the difference (S2-S1) between the linear expansion coefficient (S1) of the polycarbonate-containing layer and the linear expansion coefficient (S2) of the methacrylic resin-containing layer and the linear expansion coefficient (S1) of the polycarbonate-containing layer is-10% to + 10%.

[10] The extruded resin sheet according to [9], wherein when the extruded resin sheet is heated at 75 ℃ or 100 ℃ for 5 hours, the in-plane retardation value of at least a part in the width direction is 50 to 330nm both before and after heating,

The rate of decrease in the retardation value after heating is less than 30% relative to that before heating.

[11] The extruded resin sheet according to [9] or [10], wherein the in-plane retardation value of at least a part in the width direction is 80 to 250nm both before and after heating.

[12] the extruded resin sheet according to any one of [9] to [11], wherein a decrease rate of the retardation value after heating is less than 15% with respect to that before heating.

[13] The extruded resin sheet according to any one of [9] to [12], further comprising a scratch-resistant layer on at least one surface thereof.

Effects of the invention

According to the present invention, an extruded resin sheet with excellent surface properties and a method for producing the same can be provided, in which the occurrence of warpage due to thermal changes is small, the in-plane retardation value (Re) and the in-plane retardation axis direction are within preferred ranges.

drawings

Fig. 1 is a schematic cross-sectional view of an extruded resin sheet of a first embodiment of the present invention.

Fig. 2 is a schematic sectional view of an extruded resin sheet of a second embodiment of the present invention.

Fig. 3 is a schematic view of an apparatus for manufacturing an extruded resin sheet according to an embodiment of the present invention.

Detailed Description

[ extrusion resin sheet ]

The present invention relates to an extruded resin sheet suitable as a protective sheet for liquid crystal displays, touch panels, and the like. The extruded resin sheet of the present invention is obtained by laminating a layer containing a methacrylic resin (PM) (hereinafter, also referred to simply as a methacrylic resin-containing layer) on at least one surface of a layer containing a Polycarbonate (PC) (hereinafter, also referred to simply as a polycarbonate-containing layer).

Polycarbonate (PC) has excellent impact resistance, and methacrylic resin (PM) has excellent gloss, transparency, and scratch resistance. Therefore, the extruded resin sheet of the present invention obtained by laminating these resins is excellent in gloss, transparency, impact resistance and scratch resistance. Further, the extruded resin sheet of the present invention is produced by an extrusion molding method, and therefore, is excellent in productivity.

(methacrylic resin-containing layer)

The methacrylic resin-containing layer contains one or more methacrylic resins (PM). The methacrylic resin (PM) is preferably a homopolymer or a copolymer containing a structural unit derived from one or more kinds of hydrocarbon methacrylate (hereinafter, also simply referred to as methacrylate) including Methyl Methacrylate (MMA).

The hydrocarbon group in the methacrylate may be an acyclic aliphatic hydrocarbon group such as a methyl group, an ethyl group, or a propyl group, an alicyclic hydrocarbon group, or an aromatic hydrocarbon group such as a phenyl group.

From the viewpoint of transparency, the content of the methacrylate ester monomer unit in the methacrylic resin (PM) is preferably 50% by mass or more, more preferably 80% by mass or more, particularly preferably 90% by mass or more, and may be 100% by mass.

The methacrylic resin (PM) may contain a structural unit from one or more other monomers other than methacrylate. Examples of the other monomers include Methyl Acrylate (MA), ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, tert-butyl acrylate, hexyl acrylate, 2-ethylhexyl acrylate, nonyl acrylate, decyl acrylate, dodecyl acrylate, stearyl acrylate, 2-hydroxyethyl acrylate, acrylic esters such as 2-hydroxypropyl acrylate, 4-hydroxybutyl acrylate, cyclohexyl acrylate, 2-methoxyethyl acrylate, 3-methoxybutyl acrylate, trifluoromethyl acrylate, trifluoroethyl acrylate, pentafluoroethyl acrylate, glycidyl acrylate, allyl acrylate, phenyl acrylate, methylphenyl acrylate, benzyl acrylate, isobornyl acrylate, and 3-dimethylaminoethyl acrylate. Among them, from the viewpoint of availability, MA, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, and tert-butyl acrylate are preferable, MA and ethyl acrylate are more preferable, and MA is particularly preferable. The content of the structural unit derived from another monomer in the methacrylic resin (PM) is preferably 10% by mass or less, more preferably 5% by mass or less, and particularly preferably 2% by mass or less.

The methacrylic resin (PM) is preferably obtained by polymerizing one or more methacrylic acid esters containing MMA and other monomers as necessary. When two or more monomers are used, the polymerization is usually carried out after preparing a monomer mixture by mixing two or more monomers. The polymerization method is not particularly limited, and radical polymerization methods such as bulk polymerization, suspension polymerization, solution polymerization, and emulsion polymerization are preferred from the viewpoint of productivity.

The methacrylic resin (PM) preferably has a weight average molecular weight (Mw) of 40000 to 500000. When Mw is 40000 or more, the methacrylic resin-containing layer has excellent scratch resistance and heat resistance, and when Mw is 500000 or less, the methacrylic resin-containing layer has excellent moldability.

In the present specification, "Mw" is a standard polystyrene conversion value measured by Gel Permeation Chromatography (GPC) unless otherwise specified.

In the present specification, the glass transition temperature of the methacrylic resin containing layer is represented by tg (m). The lower limit of tg (m) is preferably 110 ℃, more preferably 115 ℃, particularly preferably 120 ℃, and most preferably 125 ℃, and the upper limit of tg (m) is preferably 160 ℃, more preferably 155 ℃, and particularly preferably 150 ℃, for the reason that an extruded resin sheet having good surface properties and small warpage due to residual stress can be easily obtained.

< methacrylic resin (B) >

In one embodiment of the present invention, the methacrylic resin-containing layer may contain a methacrylic resin (B) containing a structural unit derived from MMA and an alicyclic hydrocarbon ester.

hereinafter, the alicyclic hydrocarbon ester is referred to as "methacrylate (I)". Examples of the methacrylic acid ester (I) include monocyclic aliphatic hydrocarbon methacrylic acid esters such as cyclohexyl methacrylate, cyclopentyl methacrylate and cycloheptyl methacrylate; 2-norbornyl methacrylate, 2-methyl-2-norbornyl methacrylate, 2-ethyl-2-norbornyl methacrylate, 2-isobornyl methacrylate, 2-methyl-2-isobornyl methacrylate, 2-ethyl-2-isobornyl methacrylate, 8-tricyclo [5.2.1.0 ] methacrylate^2,6]Decyl ester (TCDMA), 8-methyl-8-tricyclo [5.2.1.0 ] methacrylate^2,6]Decyl ester, methacrylic acid 8-ethyl-8-tricyclo [5.2.1.0^2,6]Polycyclic aliphatic hydrocarbon methacrylates such as decyl methacrylate, 2-adamantyl methacrylate, 2-methyl-2-adamantyl methacrylate, 2-ethyl-2-adamantyl methacrylate, 1-adamantyl methacrylate, 2-fenchyl methacrylate, 2-methyl-2-fenchyl methacrylate, and 2-ethyl-2-fenchyl methacrylate; and so on. Among them, polycyclic aliphatic hydrocarbon methacrylate is preferable, and 8-tricyclo [5.2.1.0 ] methacrylate is more preferable^2,6]decyl ester (TCDMA).

As the methacrylic resin (B), a methacrylic resin containing a structural unit derived from MMA and a polycyclic aliphatic hydrocarbon methacrylate is more preferableThe esters (BX), particularly preferably comprising 8-tricyclo [5.2.1.0 ] from MMA and methacrylic acid^{2 ,6}]Methacrylic resin (BX-a) of structural units of decyl ester (TCDMA).

From the viewpoint of hardness, the content of the MMA monomer unit in the methacrylic resin (B) is preferably 40 to 80 mass%, more preferably 50 to 80 mass%, and particularly preferably 50 to 60 mass%.

The content of the methacrylate ester (I) monomer unit in the methacrylic resin (B) is preferably 20 to 60% by mass, more preferably 20 to 50% by mass, and particularly preferably 40 to 50% by mass, from the viewpoint of reducing the linear expansion ratio (SR) described later and from the viewpoint of making the glass transition temperature (tg (m)) 110 ℃ or higher. When the content of the monomer unit of the methacrylic acid ester (I) exceeds 60% by mass, there is a possibility that the impact resistance of the methacrylic resin-containing layer is lowered.

< methacrylic resin composition (MR) >

In another embodiment of the present invention, the methacrylic resin-containing layer may include a methacrylic resin composition (MR) containing the methacrylic resin (IV) and the SMA resin (hereinafter also referred to simply as the resin composition (MR)).

In the present specification, the "SMA resin" refers to a copolymer containing a structural unit derived from one or more aromatic vinyl compounds (II) and a structural unit derived from one or more anhydrides (III) including Maleic Anhydride (MAH), and more preferably containing a structural unit derived from MMA.

The methacrylic resin composition (MR) may preferably contain 5 to 80 mass% of the methacrylic resin (IV) and 95 to 20 mass% of the SMA resin.

The methacrylic resin (IV) is preferably a homopolymer or a copolymer containing a structural unit derived from one or more methacrylic acid esters containing MMA. The methacrylate is not particularly limited, but from the viewpoint of availability, MMA, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, t-butyl methacrylate and the like are preferable, and MMA is particularly preferable. The content of the methacrylate ester monomer unit in the methacrylic resin (IV) is preferably 90% by mass or more, more preferably 95% by mass or more, particularly preferably 98% by mass or more, and may be 100% by mass.

As the methacrylic resin (IV), a methacrylic resin (a) containing an MMA monomer unit is preferable. The content of the MMA monomer unit in the methacrylic resin (a) is preferably 90% by mass or more, more preferably 95% by mass or more, particularly preferably 98% by mass or more, and most preferably 100% by mass.

The methacrylic resin (IV) may contain a structural unit derived from one or more other monomers other than methacrylic acid esters. As the other monomer, the monomer described in the description of the methacrylic resin (PM) can be used. The content of the other monomer unit in the methacrylic resin (IV) is preferably 10% by mass or less, more preferably 5% by mass or less, and particularly preferably 2% by mass or less.

The content of the methacrylic resin (IV) in the resin composition (MR) is preferably 80% by mass or less, more preferably 5 to 55% by mass, and particularly preferably 10 to 50% by mass, from the viewpoint of the glass transition temperature (tg (m)) being 110 ℃ or higher.

The SMA resin is a copolymer containing structural units derived from one or more aromatic vinyl compounds (II) and one or more acid anhydrides (III) containing MAH.

as the aromatic vinyl compound (II), styrene (St); nuclear alkyl-substituted styrenes such as 2-methylstyrene, 3-methylstyrene, 4-ethylstyrene, and 4-tert-butylstyrene; alpha-alkyl substituted styrenes such as alpha-methylstyrene and 4-methyl-alpha-methylstyrene. Among them, styrene (St) is preferable from the viewpoint of availability. The content of the aromatic vinyl compound (II) monomer unit in the SMA resin is preferably 50 to 85 mass%, more preferably 55 to 82 mass%, and particularly preferably 60 to 80 mass%, from the viewpoint of transparency and moisture resistance of the resin composition (MR).

As the acid anhydride (III), at least Maleic Anhydride (MAH) is used from the viewpoint of availability, and other acid anhydrides such as citraconic anhydride and dimethylmaleic anhydride may be used as necessary. The content of the acid anhydride (III) monomer unit in the SMA resin is preferably 15 to 50 mass%, more preferably 18 to 45 mass%, and particularly preferably 20 to 40 mass%, from the viewpoint of transparency and heat resistance of the resin composition (MR).

the SMA resin may contain a structural unit derived from one or more methacrylate monomers other than the aromatic vinyl compound (II) and the acid anhydride (III). As the methacrylic acid esters, there may be mentioned MMA, ethyl methacrylate, propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, t-butyl methacrylate, 2-ethylhexyl methacrylate, cyclohexyl methacrylate, phenyl methacrylate, benzyl methacrylate and 1-phenylethyl methacrylate. Among them, alkyl methacrylate in which the number of carbon atoms of the alkyl group is 1 to 7 is preferable. MMA is particularly preferable from the viewpoint of heat resistance and transparency of the SMA resin. The content of the methacrylate monomer unit in the SMA resin is preferably 1 to 35 mass%, more preferably 3 to 30 mass%, and particularly preferably 5 to 26 mass%, from the viewpoint of the bending workability and transparency of the extruded resin sheet. In this case, the content of the aromatic vinyl compound (II) monomer unit is preferably 50 to 84% by mass, and the content of the acid anhydride (III) monomer unit is preferably 15 to 49% by mass.

The SMA resin may have a structural unit derived from a monomer other than the aromatic vinyl compound (II), the acid anhydride (III), and the methacrylate ester. As the other monomer, the monomer described in the description of the methacrylic resin (PM) can be used. The content of the other monomer unit in the SMA resin is preferably 10% by mass or less, more preferably 5% by mass or less, and particularly preferably 2% by mass or less.

The SMA resin is obtained by polymerizing an aromatic vinyl compound (II), an acid anhydride (III), and a methacrylate ester used as needed, and other monomers used as needed. In this polymerization, generally, a monomer mixture is prepared by mixing two or more kinds of monomers, and then polymerization is performed. The polymerization method is not particularly limited, and radical polymerization methods such as bulk polymerization and solution polymerization are preferred from the viewpoint of productivity.

The Mw of the SMA resin is preferably 40000-300000. When Mw is 40000 or more, the methacrylic resin-containing layer has excellent scratch resistance and impact resistance, and when Mw is 300000 or less, the methacrylic resin-containing layer has excellent moldability.

The content of the SMA resin in the resin composition (MR) is preferably 20% by mass or more, more preferably 45 to 95% by mass, and particularly preferably 50 to 90% by mass, from the viewpoint of reducing the linear expansion ratio (SR) described later and from the viewpoint of setting the glass transition temperature (tg (m)) to 110 ℃.

The resin composition (MR) is obtained by, for example, mixing the methacrylic resin (IV) with the SMA resin. The mixing method includes a melt mixing method and a solution mixing method. In the melt-mixing method, melt-mixing can be carried out in an inert gas atmosphere such as nitrogen, argon, or helium, if necessary, using a single-screw or multi-screw mixer, a roll mill, a banbury mixer, or a kneader. In the solution mixing method, the methacrylic resin (IV) and the SMA resin may be dissolved in an organic solvent such as toluene, tetrahydrofuran, and methyl ethyl ketone and mixed.

The methacrylic resin-containing layer may contain a methacrylic resin (PM) and, if necessary, one or more other polymers.

In one embodiment, the methacrylic resin-containing layer may contain the methacrylic resin (B) and one or more other polymers as needed.

In another embodiment, the methacrylic resin-containing layer is composed of a methacrylic resin composition (MR), and the methacrylic resin composition (MR) may contain the methacrylic resin (IV), the SMA resin, and one or more other polymers as needed.

The other polymer is not particularly limited, and examples thereof include other thermoplastic resins such as polyolefins such as polyethylene and polypropylene, polyamides, polyphenylene sulfides, polyether ether ketones, polyesters, polysulfones, polyphenylene ethers, polyimides, polyetherimides, and polyacetals; thermosetting resins such as phenol resins, melamine resins, silicone resins, and epoxy resins. The content of the other polymer in the methacrylic resin-containing layer is preferably 10% by mass or less, more preferably 5% by mass or less, and particularly preferably 2% by mass or less.

the methacrylic resin-containing layer may contain various additives as required. Examples of the additives include antioxidants, thermal deterioration inhibitors, ultraviolet absorbers, light stabilizers, lubricants, mold release agents, polymer processing aids, antistatic agents, flame retardants, dyes and pigments, light diffusing agents, delustering agents, impact modifiers such as core-shell particles and block copolymers, and phosphors. The content of the additive may be appropriately set within a range not impairing the effects of the present invention. For example, the content of the antioxidant is preferably 0.01 to 1 part by mass, the content of the ultraviolet absorber is preferably 0.01 to 3 parts by mass, the content of the light stabilizer is preferably 0.01 to 3 parts by mass, the content of the lubricant is preferably 0.01 to 3 parts by mass, and the content of the dye/pigment is preferably 0.01 to 3 parts by mass, based on 100 parts by mass of the resin constituting the methacrylic resin-containing layer.

When the methacrylic resin (PM) or the methacrylic resin (B) contains another polymer and/or additive, the timing of addition may be at the time of polymerization of the methacrylic resin (PM) or the methacrylic resin (B) or after polymerization. When the methacrylic resin composition (MR) contains other polymers and/or additives, the addition timing may be the polymerization of the methacrylic resin (IV) and/or the SMA resin, or the mixing of these resins may be performed or followed.

From the viewpoint of stability of the heat melt molding, the Melt Flow Rate (MFR) of the constituent resin of the methacrylic resin-containing layer is preferably 1 to 10g/10 min, more preferably 1.5 to 7g/10 min, and particularly preferably 2 to 4g/10 min. In the present specification, unless otherwise specified, the MFR of the constituent resin of the methacrylic resin-containing layer is a value measured at a temperature of 230 ℃ and under a load of 3.8kg using a melt flow rate meter.

(polycarbonate-containing layer)

The polycarbonate-containing layer contains one or more Polycarbonates (PC). The Polycarbonate (PC) is preferably obtained by copolymerizing one or more dihydric phenols with one or more carbonate precursors. Examples of the production method include an interfacial polymerization method in which an aqueous solution of a dihydric phenol and an organic solvent solution of a carbonate precursor are reacted at an interface, and an ester exchange method in which a dihydric phenol and a carbonate precursor are reacted at high temperature under reduced pressure without a solvent.

Examples of the dihydric phenol include 2, 2-bis (4-hydroxyphenyl) propane (commonly known as bisphenol a), 1-bis (4-hydroxyphenyl) ethane, 1-bis (4-hydroxyphenyl) cyclohexane, 2-bis (3-methyl-4-hydroxyphenyl) propane, 2-bis (3, 5-dimethyl-4-hydroxyphenyl) propane, bis (4-hydroxyphenyl) sulfide, and bis (4-hydroxyphenyl) sulfone, and bisphenol a is preferable. Examples of the carbonate precursor include carbonyl halides such as phosgene; carbonates such as diphenyl carbonate; haloformates such as dihaloformates of dihydric phenols; and so on.

The Mw of the Polycarbonate (PC) is preferably 10000 to 100000, more preferably 20000 to 70000. When Mw is 10000 or more, the polycarbonate-containing layer has excellent impact resistance and heat resistance, and when Mw is 100000 or less, the polycarbonate-containing layer has excellent moldability.

Commercially available Polycarbonate (PC) can be used. Examples thereof include "カ リ バ ー (registered trademark)" and "SD ポ リ カ (registered trademark)" manufactured by Sumika Styron Polycarbonate, and "ユ ー ピ ロ ン/ノ バ レ ッ ク ス (registered trademark)" manufactured by Mitsubishi engineering plastics, and "タ フ ロ ン (registered trademark)" manufactured by Kashin Kaisha and "パ ン ラ イ ト (registered trademark)" manufactured by Kaisha.

The polycarbonate-containing layer may contain one or more other polymers and/or various additives as required. As the other polymer and various additives, the same ones as described in the description of the methacrylic resin-containing layer can be used. The content of the other polymer in the polycarbonate-containing layer is preferably 15% by mass or less, more preferably 10% by mass or less, and particularly preferably 5% by mass or less. The content of the additive may be appropriately set within a range not impairing the effects of the present invention. The amount of the antioxidant is preferably 0.01 to 1 part by mass, the amount of the ultraviolet absorber is preferably 0.01 to 3 parts by mass, the amount of the light stabilizer is preferably 0.01 to 3 parts by mass, the amount of the lubricant is preferably 0.01 to 3 parts by mass, and the amount of the dye/pigment is preferably 0.01 to 3 parts by mass, based on 100 parts by mass of the Polycarbonate (PC).

When another polymer and/or additive is added to the Polycarbonate (PC), the timing of addition may be at the time of polymerization of the Polycarbonate (PC) or after the polymerization.

In the present specification, the glass transition temperature of the polycarbonate-containing layer is represented by tg (pc). Tg (PC) is preferably 120 to 160 ℃, more preferably 135 to 155 ℃, and particularly preferably 140 to 150 ℃.

From the viewpoint of stability of the hot melt molding, the MFR of the resin constituting the polycarbonate-containing layer is preferably 1 to 30g/10 min, more preferably 3 to 20g/10 min, and particularly preferably 5 to 10g/10 min. In the present specification, unless otherwise specified, the MFR of the resin constituting the polycarbonate-containing layer is a value measured by using a melt flow rate meter under conditions of a temperature of 300 ℃ and a load of 1.2 kg.

(Linear expansion ratio (SR))

In the extruded resin sheet of the present invention, the ratio ((S2-S1)/S1) of the difference (S2-S1) between the linear expansion coefficient (S1) of the polycarbonate-containing layer and the linear expansion coefficient (S2) of the methacrylic resin-containing layer and the linear expansion coefficient (S1) of the polycarbonate-containing layer is defined as a linear expansion coefficient ratio (SR).

The linear expansion ratio (SR) is-10% to + 10%, preferably-10% to + 5%, and more preferably-5% to + 2%, from the viewpoint of reducing warpage due to thermal change or the like. The linear expansion ratio (SR) may be-10% to-0.1%, -5% to-0.1%, + 0.1% to + 10%, + 0.1% to + 5% or + 0.1% to + 2%. When the linear expansion ratio (SR) is within this range, an extruded resin sheet having good surface properties and small warpage due to residual stress can be easily obtained.

(thickness of each layer and extruded resin plate)

The thickness of the methacrylic resin-containing layer is preferably 20 to 200. mu.m, more preferably 25 to 150. mu.m, particularly preferably 30 to 100. mu.m, and the thickness of the polycarbonate-containing layer is preferably 0.1 to 3.0mm, more preferably 0.5 to 2.0mm, for the reason that the balance between scratch resistance and impact resistance is excellent.

The thickness of the whole extruded resin sheet of the present invention is not particularly limited, and is preferably 0.1 to 3.0mm, more preferably 0.5 to 2.0mm in the application to a protective sheet such as a liquid crystal display, a touch panel display, or the like. If the thickness is too thin, the rigidity may be insufficient, and if the thickness is too thick, the weight reduction of the liquid crystal display, the touch panel display, and the like may be hindered.

(laminated Structure)

The extruded resin sheet of the present invention may have another resin layer as long as the methacrylic resin-containing layer is laminated on at least one surface of the polycarbonate-containing layer. The laminated structure of the extruded resin sheet of the present invention includes a two-layer structure of a polycarbonate-containing layer and a methacrylic resin-containing layer; a three-layer structure of a methacrylic resin-containing layer-a polycarbonate-containing layer-a methacrylic resin-containing layer; a three-layer structure of a methacrylic resin-containing layer-a polycarbonate-containing layer-another resin layer; other resin layer-methacrylic resin containing layer-polycarbonate containing layer three-layer structure; and so on.

Fig. 1 and 2 are schematic cross-sectional views of extruded resin sheets according to first and second embodiments of the present invention. In the figure, reference numerals 16X and 16Y denote extruded resin sheets, reference numeral 21 denotes a polycarbonate-containing layer, and reference numerals 22, 22A, and 22B denote methacrylic resin-containing layers. The extruded resin sheet 16X of the first embodiment has a two-layer structure of a polycarbonate-containing layer 21-a methacrylic resin-containing layer 22. The extruded resin sheet 16Y of the second embodiment has a three-layer structure of a first methacrylic resin containing layer 22A-a polycarbonate containing layer 21-a second methacrylic resin containing layer 22B. The structure of the extruded resin sheet may be changed in design as appropriate.

(curing coating film)

The extruded resin sheet of the present invention may have a cured coating film on at least one outermost surface as required. The cured coating film can function as a scratch-resistant layer or a low-reflective layer for achieving a visibility-improving effect. The cured coating can be formed by a known method (see patent documents 5 and 6 listed in "background art").

the thickness of the scratch-resistant (hard coat) cured coating (scratch-resistant layer) is preferably 2 to 30 μm, more preferably 5 to 20 μm. If the thickness is too thin, the surface hardness becomes insufficient, and if the thickness is too thick, cracks may occur due to bending in the production process.

The thickness of the low-reflective cured coating (low-reflective layer) is preferably 80 to 200nm, more preferably 100 to 150 nm. If the thickness is too thin or too thick, the low reflection performance may be insufficient.

[ method for producing extruded resin sheet ]

The method for producing the extruded resin sheet of the present invention having the above-described configuration will be described below. The extruded resin sheet of the present invention is produced by a production method including coextrusion molding.

(Process (X))

The constituent resins of the polycarbonate-containing layer and the methacrylic resin-containing layer are respectively heated and melted, and a thermoplastic resin laminate having the methacrylic resin-containing layer laminated on at least one surface of the polycarbonate-containing layer is coextruded in a molten state from a T-die having a wide discharge opening.

The molten resins for the polycarbonate-containing layer and for the methacrylic resin-containing layer are preferably melt-filtered with a filter before lamination. By performing multilayer molding using the respective molten resins after the melt filtration, an extruded resin sheet with few defects due to foreign matters and gels can be obtained. The filter material of the filter is appropriately selected depending on the use temperature, viscosity, filtration accuracy, and the like. Examples thereof include nonwoven fabrics composed of polypropylene, polyester, rayon, cotton, glass fiber, and the like; a sheet-like material made of cellulose impregnated with a phenol resin; sintering the metal fiber non-woven fabric into a sheet; sintering the metal powder into a sheet; a metal mesh; and combinations thereof, and the like. Among them, a filter obtained by laminating a plurality of sintered metal fiber nonwoven fabric sheets is preferable from the viewpoint of heat resistance and durability. The filtration accuracy of the filter is not particularly limited, but is preferably 30 μm or less, more preferably 15 μm or less, and particularly preferably 5 μm or less.

Examples of the lamination method include a feed block (feed block) method in which the layers are laminated before the layers flow into the T-die, and a multi-manifold method in which the layers are laminated inside the T-die. From the viewpoint of improving the interface smoothness between layers of the extruded resin sheet, the multi-manifold system is preferable.

The molten thermoplastic resin laminate coextruded from the T-die was cooled using a plurality of cooling rolls. In the present invention, the molten thermoplastic resin laminate is sandwiched between the nth (where n.gtoreq.1) cooling roll and the (n + 1) th cooling roll using three or more cooling rolls adjacent to each other, wound around the (n + 1) th cooling roll, and cooled by repeating this operation a plurality of times from n to 1. For example, in the case of using three cooling rolls, the number of repetitions is 2.

examples of the cooling roll include a metal roll and an elastic roll having a metal film on the outer peripheral portion thereof (hereinafter also referred to as a metal elastic roll). As the metal roll, a drilling roll, a stretching roll, and the like can be cited. The surface of the metal roller may be a mirror surface, or may have a pattern, an unevenness, or the like. The metal elastic roll includes, for example, a roll made of stainless steel or the like, a metal thin film made of stainless steel or the like covering the outer peripheral surface of the roll, and a fluid sealed between the roll and the metal thin film, and can exhibit elasticity due to the presence of the fluid. The thickness of the metal thin film is preferably about 2mm to about 5 mm. The metal film preferably has flexibility, and the like, and preferably has a seamless structure without a welded portion. The metal elastic roller provided with such a metal film is excellent in durability, and can be used similarly to a normal mirror-surface roller when the metal film is mirror-surface-finished, and can be used as a roller capable of transferring the shape when a pattern, an unevenness, or the like is provided on the metal film, and therefore, is excellent in usability.

The extruded resin sheet obtained after cooling is pulled away by a pull-away roller. The above steps of co-extrusion, cooling and drawing are carried out continuously. In the present specification, the object in a heated and molten state is mainly referred to as a "thermoplastic resin laminate" and the cured product is referred to as an "extruded resin sheet", but there is no clear limit therebetween.

as an embodiment, a schematic view of a manufacturing apparatus including a T-die 11, first to third cooling rolls 12 to 14, and a pair of take-off rolls 15 is shown in FIG. 3. The thermoplastic resin laminate co-extruded from the T-die 11 is cooled by first to third cooling rolls 12 to 14 and separated by a pair of separation rolls 15. In the illustrated example, the third cooling roll 14 is a "cooling roll on which the thermoplastic resin laminate is wound last (hereinafter, simply referred to as a last cooling roll)".

The fourth and subsequent cooling rollers may be provided adjacent to the subsequent stage of the third cooling roller 14. In this case, the cooling roll on which the thermoplastic resin laminate is wound last becomes the "last cooling roll". The conveyance roller may be provided between a plurality of cooling rollers and the pull-off roller adjacent to each other as needed, but the conveyance roller is not included in the "cooling roller".

The structure of the manufacturing apparatus may be appropriately modified in design without departing from the scope of the present invention.

In the production method of the present invention, the overall Temperature (TX) of the thermoplastic resin laminate when sandwiched between the second cooling roll and the third cooling roll is set to be not less than 10 ℃ relative to the glass transition temperature (tg (pc)) + of the polycarbonate-containing layer. The Temperature (TX) is measured by the method described in [ example ] below.

In the production method of the present invention, The Temperature (TT) of the thermoplastic resin laminate at the position of peeling from the last cooling roll (the third cooling roll in FIG. 3) is set to a range of-2 ℃ to +19 ℃ relative to the glass transition temperature (Tg (PC)) of the polycarbonate-containing layer. The Temperature (TT) is preferably from-2 ℃ to-0.1 ℃ or from +0.1 ℃ to +19 ℃ relative to (Tg (PC)), more preferably from-2 ℃ to +15 ℃ relative to (Tg (PC)), and particularly preferably from +0.1 ℃ to +15 ℃ relative to (Tg (PC)).

If the temperature TT is too low relative to tg (pc), the shape of the last cooling roller (the third cooling roller in fig. 3) is transferred to the extruded resin sheet, and the warpage may increase. On the other hand, if the temperature TT is too high relative to the glass transition temperature (Tg) of the resin layer in contact with the last cooling roll (the third cooling roll in fig. 3), the surface properties of the extruded resin sheet may be reduced. The Temperature (TT) was measured by the method described in [ example ] below.

in the present invention, in order to obtain an extruded resin sheet with less warpage, it is preferable that the linear expansion ratio (SR) be from-10% to + 10% and the glass transition temperature (Tg (M)) of the methacrylic resin-containing layer be 110 ℃ or higher.

"retardation" is the phase difference between light in the direction of the main chain of the molecule and light in the direction perpendicular thereto. It is generally known that a polymer can be formed into an arbitrary shape by heating and melting, but the orientation of the molecules is delayed by stress generated during heating and cooling. Therefore, in order to control retardation, the orientation of the molecules needs to be controlled. The molecular orientation is caused by, for example, stress at the time of molding in the vicinity of the glass transition temperature (Tg) of the polymer. In the present specification, "retardation" means in-plane retardation unless otherwise specified.

The present inventors have found that by controlling the molecular orientation by optimizing the production conditions during extrusion molding, the Re value of the extruded resin sheet after molding can be optimized, and further, thermal variation in the Re value can be suppressed.

It is preferable that before and after heating, the Re value of at least a part of the extruded resin sheet in the width direction is 50 to 330nm, and the reduction rate of the Re value of the extruded resin sheet before and after heating is less than 30%.

< relationship between peripheral speed ratio and Re value >

In the present specification, unless otherwise specified, "circumferential speed ratio" is a ratio of the circumferential speed of any cooling roll or take-off roll other than the second cooling roll with respect to the second cooling roll. The peripheral speed of the second cooling roll is indicated as V2, the peripheral speed of the third cooling roll is indicated as V3 and the peripheral speed of the take-off roll is indicated as V4.

The inventors of the present invention variously evaluated the relationship between the peripheral speed ratio (V3/V2) of the third cooling roll to the second cooling roll and the Re value, and as a result, they found that the Re value did not increase significantly even if the peripheral speed ratio (V3/V2) was increased. The reason for this is presumed as follows.

In the production method of the present invention, The Temperature (TT) of the thermoplastic resin laminate at the position of peeling from the last cooling roll (the third cooling roll in fig. 3) is adjusted to the range of-2 ℃ to +19 ℃ relative to the glass transition temperature (tg (pc)) of the polycarbonate-containing layer. Here, attention is paid to the cooling process of the thermoplastic resin laminate by the last cooling roll. Since the thermoplastic resin laminate is cooled while contacting the last cooling roll, the overall temperature of the thermoplastic resin laminate at the position where the thermoplastic resin laminate is most initially in contact with the last cooling roll is higher than the overall temperature (TT) of the thermoplastic resin laminate at the position where the thermoplastic resin laminate is peeled off from the last cooling roll. Therefore, the temperature of the entire thermoplastic resin laminate at the time of the first contact with the last cooling roll is higher than the range of-2 ℃ to +19 ℃ relative to the glass transition temperature (Tg (PC)) of the polycarbonate-containing layer, and is, for example, about +20 ℃ or higher relative to the glass transition temperature (Tg (PC)). Under these conditions, even if a large tensile stress is applied to the extruded resin sheet by increasing the circumferential speed ratio (V3/V2), the Re value is not expected to increase significantly because the molecules of the resin are in a high temperature range in which orientation is difficult to occur.

the inventors of the present invention variously evaluated the relationship between the peripheral speed ratio (V4/V2) of the take-off roll to the second cooling roll and the Re value, and found that the larger the peripheral speed ratio (V4/V2), the larger the Re value. The reason for this is presumed as follows.

When a large tensile stress is applied to the extruded resin sheet by increasing the peripheral speed ratio of the take-off roll under the condition that The Temperature (TT) is adjusted to a range of-2 to +19 ℃ relative to the glass transition temperature (tg (pc)) of the polycarbonate-containing layer, the Re value is estimated to increase because the circumferential speed ratio is in a temperature range in which molecules of the resin are likely to be oriented.

< relationship between peripheral speed ratio and rate of decrease in Re value after heating >

Therefore, the following steps are carried out: when the circumferential speed ratio (V4/V2) is increased under the condition that The Temperature (TT) is lower than the glass transition temperature (tg (pc)) of the polycarbonate-containing layer (tg) of from-2 to +19 ℃), the Re value tends to increase and the rate of decrease in Re value after heating tends to increase (see comparative examples 1 and 2 described later).

Therefore, the following steps are carried out: on the other hand, when the peripheral speed ratio (V4/V2) is increased under the condition that The Temperature (TT) is in the range of-2 ℃ to +19 ℃ relative to the glass transition temperature (Tg (PC)) of the polycarbonate-containing layer, the Re value is increased, but the rate of decrease in the Re value after heating is not significantly changed (see examples 10 and 11 described later).

The reason for this is presumed as follows. When The Temperature (TT) is adjusted to the range of-2 ℃ to +19 ℃ with respect to the glass transition temperature (tg (pc)) of the polycarbonate-containing layer, the molecules are oriented and the Re value is increased by increasing the peripheral speed ratio of the take-off roll and applying a large tensile stress to the extruded resin sheet, but since the heating temperature is lower than the glass transition temperature (tg (pc)) of the polycarbonate-containing layer, the orientation of the molecules is not easily relaxed, and it is estimated that the reduction rate of the Re value does not change greatly.

From the above findings, it was found that the rate of decrease in the Re value and the Re value after heating can be controlled by controlling The Temperature (TT) to a range of-2 ℃ to +19 ℃ relative to the glass transition temperature (Tg) (PC) of the polycarbonate-containing layer and setting the circumferential velocity ratio (V4/V2) within a preferred range.

Specifically, in the production method of the present invention, the peripheral speed ratio (V4/V2) is set to 0.98 or more and less than 1.0. When the circumferential speed ratio (V4/V2) is 1.0 or more, the Re value may be larger than 330nm (see comparative examples 5 to 7 described later). When the peripheral speed ratio (V4/V2) is less than 0.98, Re may be less than 50nm (see comparative example 8 described later). From the viewpoint of optimizing the Re value, the circumferential speed ratio (V4/V2) is more preferably 0.985 to 0.995 (see examples 1 to 10 and 12 to 15 described later).

< variation of axial direction with respect to retardation in plane >

The axial direction of the in-plane retardation depends on the orientation direction of the molecules. When the photoelastic coefficient of the resin is positive, the orthogonal direction is a fast axis and the parallel direction is a slow axis with respect to the molecular orientation direction. On the contrary, when the photoelastic coefficient of the resin is negative, the orthogonal direction is the slow axis and the parallel direction is the fast axis with respect to the orientation direction of the molecules. That is, the fast axis and the slow axis are in a mutually orthogonal relationship. In addition, the orientation direction of the molecules depends on the stretching direction, and in general, the parallel direction is a fast axis or a slow axis with respect to the extrusion direction.

The present inventors evaluated the visibility of a liquid crystal display in which the transmission axis of a polarizing plate is horizontal to the observation screen when viewed through a polarizing filter (polarizing sunglasses or the like) with respect to a sample of an extruded resin sheet cut so as to be orthogonal to the extrusion direction.

the present inventors have found that, under production conditions in which the Temperature (TX) is not less than (10 ℃) and The Temperature (TT) is in the range of (2 ℃) to (19 ℃) relative to Tg, (PC), the axial direction of in-plane retardation is not parallel to (i.e., deviates from) the extrusion direction when the circumferential speed ratio (V4/V2) is less than 1.0. Specifically, it can be seen that: the visibility is good when the angle of the slow axis or the fast axis of retardation in plane deviates from the extrusion direction by 5 ° or more and the liquid crystal display is viewed under the above evaluation conditions. Under these manufacturing conditions, it is estimated that the axial direction of in-plane retardation changes by adding up the stresses in the direction (width direction) orthogonal to the extrusion direction.

Therefore, the following steps are carried out: on the other hand, in the case where the circumferential speed ratio (V4/V2) is 1.0 or more under the manufacturing conditions (manufacturing conditions in which the Temperature (TX) is set to be not less than (pc) +10 ℃ relative to tg and The Temperature (TT) is set to be in the range of-2 ℃ to +19 ℃ relative to tg), the angle of the slow axis or the fast axis of retardation in the plane relative to the extrusion direction is parallel or nearly parallel to less than 5 °, and the visibility is deteriorated when the liquid crystal display is viewed under the above evaluation conditions. It is presumed that the stresses in the width direction are added under the manufacturing conditions, but since the peripheral speed ratio (V4/V2) is made larger than 1.0 or more, the stress in the extrusion direction is significantly increased, and therefore, the influence of the stress in the width direction is reduced.

In addition, it is known that: under manufacturing conditions different from those described above, for example, under conditions where The Temperature (TT) is lower than the range of tg (pc) -2 ℃ to +19 ℃, even if the peripheral speed ratio (V4/V2) is made smaller than 1.0, the angle of the slow axis or the fast axis of retardation in the plane with respect to the extrusion direction is made parallel or nearly parallel to less than 5 °, and when the liquid crystal display is viewed under the above evaluation conditions, the visibility is deteriorated.

< retardation value in plane (Re) >

The Re value of the extruded resin sheet is not particularly limited. In the application of a protective sheet such as a liquid crystal display and a touch panel, when the Re value is greater than 330nm, when the sheet is viewed through a polarizing filter such as a polarizing sunglass, the difference in transmittance at each wavelength in the visible light range becomes large, and various colors are visible, and there is a possibility that the visibility is lowered, and when the Re value is less than 50nm, the transmittance at all wavelengths in the visible light range is lowered, and there is a possibility that the visibility is lowered. From the viewpoint of visibility, Re is preferably 50 to 330 nm. Within this range, the larger the value is, the more the luminance increases, and the smaller the value is, the sharper the color tends to be. From the viewpoint of balance between brightness and color, the Re value is more preferably 80 to 250 nm. At least a part of Re in the width direction is preferably 50 to 330nm, more preferably 80 to 250 nm.

< heating conditions >

The heating conditions for evaluating the reduction rate of the Re value of the extruded resin sheet may be set to a constant temperature within a range of 75 to 100 ℃ and a constant time within a range of 1 to 30 hours. For example, the evaluation may be carried out under the conditions of 5 hours at 75 ℃ or 5 hours at 100 ℃. For example, evaluation can be carried out by heating the test piece in an oven controlled at 100 ℃. + -. 3 ℃ or 75 ℃. + -. 3 ℃ for 5 hours. The heating conditions are temperature and time of heating in a normal process of forming a cured coating film. Therefore, it is preferable that the Re value can be maintained in an appropriate range when heating under the above conditions is performed for evaluation.

According to the manufacturing method of the present invention, the following extruded resin sheet can be manufactured: when the absolute value of the angle of the slow axis or the fast axis of retardation in a plane is 5 to 45 DEG when the axis parallel to the extrusion direction is 0 DEG, the glass transition temperature Tg (M) of the methacrylic resin-containing layer is 110 ℃ or higher, and the layer is heated at a constant temperature in the range of 75 to 100 ℃ for 5 hours, the Re value of at least a part in the width direction is 50 to 330nm, preferably 80 to 250nm, both before and after heating, and the rate of decrease in retardation value after heating is less than 30%, preferably less than 15%, relative to before heating.

(Process (Y))

In the production method of the present invention, in order to more stably impart the above-described characteristics and more stably obtain an extruded resin sheet suitable as a protective sheet for a liquid crystal display, a touch panel, or the like, the step (X) may be followed by the step (Y) of heating the extruded resin sheet at a temperature of 65 to 110 ℃ for 1 to 30 hours.

In this case, it is preferable that: in the extruded resin sheet before the step (Y), the absolute value of the angle of the slow axis or the fast axis of retardation in the plane when the axis parallel to the extrusion direction is 0 DEG is 5 to 45 DEG, the Re value of at least a part of the extruded resin sheet in the width direction before and after the step (Y) is 50 to 330nm, preferably 80 to 250nm, and the reduction rate of the step (Y) of the extruded resin sheet after the step (Y) before the step (Y) is less than 30%, preferably less than 15%.

As described above, according to the present invention, it is possible to provide an extruded resin sheet with less occurrence of warpage due to thermal change, appropriate in-plane retardation value (Re) and in-plane retardation axis direction, and good surface properties, and a method for producing the same.

The extruded resin sheet of the present invention is an extruded resin sheet in which a methacrylic resin-containing layer is laminated on at least one surface of a polycarbonate-containing layer, and therefore is excellent in gloss, scratch resistance and impact resistance.

The extruded resin sheet of the present invention is less likely to warp due to thermal change and has a small thermal change in Re value, and therefore can withstand heating and high-temperature use environments in a step of forming a cured coating film that functions as a scratch-resistant layer or the like, and is excellent in productivity and durability.

The extruded resin sheet of the present invention is suitable as a protective sheet for a liquid crystal display, a touch panel, or the like, and when the extruded resin sheet of the present invention is used as a protective sheet for a liquid crystal display, a touch panel, or the like, the screen visibility is excellent.

[ use ]

The extruded resin sheet of the present invention is suitable as a protective sheet for liquid crystal displays, touch panels, and the like. For example, an ATM suitable as a financial institution such as a bank; a vending machine; protective panels for liquid crystal displays, touch panels, and the like used in portable information terminals (PDAs) such as mobile phones (including smart phones), tablet personal computers, and the like, digital audio players, portable game machines, copying machines, facsimile machines, and digital information devices such as car navigation systems, and the like.