JP2020164680A - (meth)acrylic resin film - Google Patents

Abstract

To provide a (meth)acrylic resin film having high transparency, a low phase difference, a low change in phase difference even when a temperature unevenness occurs in a film plane during stretching and excellent trimming property.SOLUTION: There is provided a (meth)acrylic resin film composed of a (meth)acrylic resin composition which comprises a (meth)acrylic resin (A) comprising a (meth)acrylic resin (A1) having a triad syndiotacticity of 45 to 58% and a (meth)acrylic resin (A2) having a triad syndiotacticity of 65% or more in a weight ratio of the (meth)acrylic resin (A1) to the (meth)acrylic resin (A2) of 1/99 to 30/70 and a thermoplastic resin (B) comprising a polycarbonate (C) and a phenoxy-based resin (D) in a weight ratio of the polycarbonate (C) to the phenoxy-based resin (D) of 1/99 to 99/1 in which the content of the thermoplastic resin (B) is 1 to 5 pts.wt. based on 100 pts.wt. of the (meth)acrylic resin (A), wherein a phase difference in a thickness direction of the (meth)acrylic resin film is -5 to 5 nm and a haze is 0.2% or less.SELECTED DRAWING: None

Description

The present invention relates to a (meth) acrylic resin film.

The (meth) acrylic resin has high transparency and weather resistance, and is suitable as an optical member, a lighting member, a signboard member, a decorative member, and the like. Films made of (meth) acrylic resin compositions are being increasingly used for optical members such as polarizer protective films and for decoration and the like.
Patent Document 1 discloses a resin composition for an optical material in which 2 to 10 parts by weight of a polycarbonate resin is mixed with 100 parts by weight of an acrylic resin as a resin composition having a small phase difference used for an optical member. There is.
When a (meth) acrylic resin is used for a film, brittleness may become an issue, and in order to improve the mechanical properties of the film, for example, a stretching treatment as described in Patent Document 2 is performed. ..

Japanese Unexamined Patent Publication No. 2014-051649 International Publication No. 2015/151466

On the other hand, in display applications, a wide film is required as a constituent member in order to increase the size and yield. However, the wide and stretched (meth) acrylic resin film has a problem that the optical properties, particularly the phase difference, become non-uniform in the plane of the film.

The present invention has been made in view of the above problems, has high transparency, has a low phase difference, and even when there is temperature unevenness in the film surface during stretching, the change in the phase difference is small and An object of the present invention is to provide a (meth) acrylic resin film having excellent trimming property.

As a result of diligent studies, the present inventors have completed the present invention including the following aspects.

That is, the present invention provides the following [1] to [7].
[1] A (meth) acrylic resin (A1) having a triplet-displayed syndiotacticity of 45 to 58% and a (meth) acrylic resin having a triplet-displayed syndiotacticity of 65% or more. (A2) is contained in the (meth) acrylic resin (A1) / (meth) acrylic resin (A2) at a mass ratio of 1/99 to 30/70, and the (meth) acrylic resin (A) and polycarbonate. It is composed of a thermoplastic resin (B) containing (C) and a phenoxy resin (D) at a mass ratio of 1/99 to 99/1 of the polycarbonate (C) / phenoxy resin (D).
A (meth) acrylic resin film comprising a (meth) acrylic resin composition in which the content of the thermoplastic resin (B) is 1 to 5 parts by mass with respect to 100 parts by mass of the (meth) acrylic resin (A). There,
A (meth) acrylic resin film having a thickness direction retardation of the (meth) acrylic resin film of −5 to 5 nm and a haze of 0.2% or less.
[2] The ratio of the tear strength in the longitudinal direction (MD) to the tear strength in the width direction (TD) measured in accordance with JIS K7128-1: 1998 is 0.9 to 1.1, the above [1]. (Meta) acrylic resin film described in.
[3] The photoelastic coefficient of the thermoplastic resin (B) is 67 × 10 ^{-12 to} 90 × 10 ^-12 Pa ^-1 , and the orientation birefringence is 80 × 10 ^{-4 to} 160 × 10 ^-4 . The (meth) acrylic resin film according to the above [1] or [2].
[4] The (meth) acrylic resin film according to any one of the above [1] to [3], which is a non-stretched film.
[5] The (meth) acrylic resin film according to any one of the above [1] to [4], which is an optical film.
[6] The (meth) acrylic resin film according to any one of the above [1] to [4], which is a decorative film.
[7] A (meth) acrylic stretched film comprising the (meth) acrylic resin film according to any one of the above [1] to [3].

According to the present invention, a (meth) acrylic system having high transparency, low phase difference, small change in phase difference and excellent trimming property even when there is temperature unevenness in the film surface during stretching. A resin film can be provided.

Hereinafter, an example of an embodiment to which the present invention is applied will be described. The numerical value specified in the present specification is a value obtained by the method disclosed in the embodiment or the embodiment. Other embodiments are also included in the scope of the present invention as long as they are consistent with the gist of the present invention.

The (meth) acrylic resin film (hereinafter, also simply referred to as a film) of the present invention has a triplet display syndiotacticity of 45 to 58% as a triplet display (meth) acrylic resin (A1). The mass ratio of the (meth) acrylic resin (A2) and the (meth) acrylic resin (A1) / (meth) acrylic resin (A2) having a syndio tacticity of 65% or more is 1/99 to 30. The (meth) acrylic resin (A) contained in / 70, and the polycarbonate (C) and the phenoxy resin (D) are contained in a mass ratio of 1/99 to 99/99 of the polycarbonate (C) / phenoxy resin (D). The (meth) acrylic resin is composed of the thermoplastic resin (B) contained in 1 and the content of the thermoplastic resin (B) is 1 to 5 parts by mass with respect to 100 parts by mass of the (meth) acrylic resin (A). It consists of a resin composition. Further, the (meth) acrylic resin film of the present invention is characterized in that the phase difference in the thickness direction is −5 to 5 nm and the haze is 0.2% or less.

<(Meta) acrylic resin (A)>
The (meth) acrylic resin (A) has a syndiotacticity of 45 to 58% in triplet display, and the (meth) acrylic resin (A1) has a syndiotacticity of 65% in triplet display. It contains the above (meth) acrylic resin (A2).

[(Meta) acrylic resin (A1)]
The (meth) acrylic resin (A1) has a triplet-displayed syndiotacticity (rr) of 45 to 58%, preferably 47 to 56%, and more preferably 49 to 54%. If the syndiotacticity (rr) is less than 45%, the heat resistance may be lowered, and if it exceeds 58%, the workability may be lowered.

In the present invention, the syndiotacticity (rr) of triplet display can be measured by the measurement method shown below.
Using a nuclear magnetic resonance apparatus (for example, manufactured by Bruker, trade name: "ULTRA SHIELD 400 PLUS"), ¹ H-NMR measurement is carried out by the following method.
(1) For 10 mg of a sample, 1 mL of deuterated chloroform was used as a deuterated solvent, the measurement temperature was room temperature (20 to 25 ° C.), and the number of integrations was 64 times, and the reference substance (TMS) was 0 ppm. The area (X) of the region of 0.6 to 0.95 ppm and the area (Y) of the region of 0.6 to 1.35 ppm are measured.
(2) Let the value calculated from the following formula (1) be the syndio tacticity (rr) (%) of the triplet display.
(X / Y) x 100 (%) (1)

The (meth) acrylic resin (A1) is not particularly limited as long as it is a resin having a structural unit derived from the (meth) acrylic acid ester, but from the viewpoint of heat resistance, the structural unit (methacrylic acid) derived from the methacrylic acid ester is used. Acrylic ester monomer unit) is preferable. Examples of the methacrylic acid ester include alkyl methacrylates such as methyl methacrylate (MMA), ethyl methacrylate, and butyl methacrylate; aryl methacrylates such as phenyl methacrylate; cyclohexyl methacrylate, norbornenyl methacrylate and the like. Examples thereof include methacrylic acid cycloalkyl ester. Of these, alkyl methacrylate esters are preferred, and MMA is particularly preferred.

The content of the methacrylic acid ester monomer unit in the (meth) acrylic resin (A1) is preferably 90% by mass or more, more preferably 95% by mass or more, and further preferably 98% by mass or more. Yes, more preferably 99% by mass or more, and particularly preferably 100% by mass.
The content of the MMA monomer unit in the (meth) acrylic resin (A1) is preferably 90% by mass or more, more preferably 95% by mass or more, and further preferably 98% by mass or more. Even more preferably, it is 99% by mass or more, and particularly preferably 100% by mass.

The (meth) acrylic resin (A1) may contain one or more monomer units other than the methacrylic acid ester monomer unit. Other monomeric units include acrylic acid alkyl esters such as methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, and 2-ethylhexyl acrylate; acrylic acid aryl esters such as phenyl acrylate; Acrylic acid cycloalkyl esters such as cyclohexyl acrylate and norbornenyl acrylate; aromatic vinyl compounds such as styrene and α-methylstyrene; acrylamide and metaacrylamide; nitriles such as acrylonitrile and metaacrylonitrile, etc. Examples thereof include structural units derived from vinyl-based monomers having only one polymerizable carbon-carbon double bond in one molecule.

The weight average molecular weight (Mw) of the (meth) acrylic resin (A1) is preferably 40,000 to 200,000, more preferably 60,000 to 150,000, and even more preferably 80,000 to 120,000. When Mw is 40,000 or more, the mechanical strength (impact resistance, toughness, etc.) of the obtained film tends to be improved, and when it is 200,000 or less, the (meth) acrylic resin film of the present invention is formed. There is a tendency that the fluidity of the (meth) acrylic resin composition is improved and the moldability is improved.

The molecular weight distribution (Mw / Mn) of the (meth) acrylic resin (A1) represented by the ratio of the weight average molecular weight (Mw) to the number average molecular weight (Mn) is preferably 1.6 to 5.0. , More preferably 1.7 to 4.0, and even more preferably 1.7 to 3.0. When a (meth) acrylic resin (A1) having a molecular weight distribution (Mw / Mn) within such a range is used, the obtained film has excellent mechanical strength. Mw and Mw / Mn can be controlled by adjusting the polymerization method of the (meth) acrylic resin (A1) and the type and / or amount of the polymerization initiator used at the time of production. In the present specification, Mw and Mn are values obtained by converting chromatograms measured by gel permeation chromatography (GPC) into molecular weights of standard polystyrene. Unless otherwise specified, Mw and Mw / Mn in the present invention are measured by the method described in Examples.

The melt flow rate (MFR) of the (meth) acrylic resin (A1) measured under the conditions of a temperature of 230 ° C. and a load of 3.8 kg is preferably 0.1 g / 10 minutes or more, more preferably 0.2. It is ~ 30 g / 10 minutes, more preferably 0.5 to 20 g / 10 minutes, and particularly preferably 1.0 to 15 g / 10 minutes. When the MFR of the (meth) acrylic resin (A1) is 0.1 g / 10 minutes or more, processability can be ensured.
The MFR can be measured under the above conditions according to JIS K7210-1: 2014.

The glass transition temperature (hereinafter, may be referred to as Tg) of the (meth) acrylic resin (A1) is preferably 100 ° C. or higher, more preferably 105 ° C. or higher, still more preferably 110 ° C. or higher. Is. The upper limit of Tg of the (meth) acrylic resin (A1) is usually 150 ° C.
Unless otherwise specified, the glass transition temperature in the present invention can be measured by the method described in Examples.

The (meth) acrylic resin (A1) can be produced by a known polymerization method such as a radical polymerization method or an anion polymerization method. For the radical polymerization method, a bulk polymerization method, a solution polymerization method, a suspension polymerization method, an emulsion polymerization method, or the like is selected, and for the anion polymerization method, a known polymerization method such as a bulk polymerization method or a solution polymerization method is selected. Can be manufactured.
The radical polymerization method can be carried out without a solvent or in a solvent, and is preferably carried out without a solvent because a (meth) acrylic resin (A1) having a low impurity concentration can be obtained. From the viewpoint of suppressing the silvering or coloring of the film, it is preferable that the polymerization reaction is carried out in an atmosphere of an inert gas such as nitrogen gas with a low dissolved oxygen content.

Examples of the polymerization initiator used in the radical polymerization method include t-hexylperoxyisopropyl monocarbonate, t-hexylperoxy2-ethylhexanoate, and 1,1,3,3-tetramethylbutylperoxy2-ethylhexa. Noate, t-butylperoxypivalate, t-hexylperoxypivalate, t-butylperoxyneodecanoeate, t-hexylperoxyneodecanoeate, 1,1,3,3-tetra Methylbutylperoxyneodecanoate, 1,1-bis (t-hexylperoxy) cyclohexane, benzoylperoxide, 3,5,5-trimethylhexanoyl peroxide, lauroyl peroxide, 2,2'-azobis ( 2-Methylpropionitrile), 2,2'-azobis (2-methylbutyronitrile), dimethyl 2,2'-azobis (2-methylpropionate) and the like. Of these, t-hexylperoxy2-ethylhexanoate, 1,1-bis (t-hexylperoxy) cyclohexane, and dimethyl 2,2'-azobis (2-methylpropionate) are preferred. The polymerization initiator may be used alone or in combination of two or more.

The 1-hour half-life temperature of the polymerization initiator is preferably 60 to 140 ° C, more preferably 80 to 120 ° C. The polymerization initiator has a hydrogen extraction ability of preferably 20% or less, more preferably 10% or less, still more preferably 5% or less. The amount of the polymerization initiator used is preferably 0.0001 to 0.02 parts by mass, more preferably 0.001 to 0, based on 100 parts by mass of the total amount of the monomers subjected to the polymerization reaction. It is 01 parts by mass, more preferably 0.005 to 0.07 parts by mass.

The hydrogen extraction capacity can be known from the technical data of the polymerization initiator manufacturer (for example, the technical data of Nippon Oil & Fats Co., Ltd. "Hydrogen extraction capacity of organic peroxides and initiator efficiency" (created in April 2003)). Can be done. Further, it can be measured by a radical trapping method (α-methylstyrene dimer trapping method) using an α-methylstyrene dimer. This measurement is generally performed as follows. First, the polymerization initiator is cleaved in the coexistence of α-methylstyrene dimer as a radical trapping agent to generate a radical fragment. Among the generated radical fragments, the radical fragment having a low hydrogen abstraction ability is added to the double bond of the α-methylstyrene dimer and captured. On the other hand, a radical fragment having a high hydrogen abstraction ability abstracts hydrogen from cyclohexane to generate a cyclohexyl radical, and this cyclohexyl radical is added to the double bond of α-methylstyrene dimer and trapped to produce a cyclohexane trapping product. Therefore, the ratio (molar fraction) of radical fragments having a high hydrogen abstraction ability to the theoretical radical fragment generation amount obtained by quantifying cyclohexane or cyclohexane capture product is determined as the hydrogen abstraction ability.

Chain transfer agents used in the radical polymerization method include n-octyl mercaptan, n-dodecyl mercaptan, t-dodecyl mercaptan, 1,4-butanedithiol, 1,6-hexanedithiol, ethylene glycol bisthiopropionate, butane. Diolbisthioglycolate, butanediol bisthiopropionate, hexanediol bisthioglycolate, hexanediol bisthiopropionate, trimethylpropanthris- (β-thiopropionate), and pentaerythritol tetraxthiopropio Examples thereof include alkyl mercaptans such as nate. Of these, monofunctional alkyl mercaptans such as n-octyl mercaptan and n-dodecyl mercaptan are preferable. The chain transfer agent may be used alone or in combination of two or more.

From the viewpoint of the moldability of the obtained resin and the mechanical strength of the film, the amount of the chain transfer agent used is preferably 0.01 to 1% by mass with respect to 100 parts by mass of the total amount of the monomers subjected to the polymerization reaction. Parts, more preferably 0.05 to 0.8 parts by mass, still more preferably 0.1 to 0.6 parts by mass, and particularly preferably 0.1 to 0.5 parts by mass. The amount of the chain transfer agent used is preferably 2500 to 10000 parts by mass, more preferably 3000 to 9000 parts by mass, and further preferably 3500 to 6000 parts by mass with respect to 100 parts by mass of the polymerization initiator.

As the solvent used in the radical polymerization method, aromatic hydrocarbons such as benzene, toluene, and ethylbenzene are preferable. As the solvent, one type can be used alone or two or more types can be used in combination. The amount of the solvent used is 100 parts by mass with respect to 100 parts by mass of the polymerization reaction raw material (mixture containing one or more monomers, a polymerization initiator, a chain transfer agent, etc.) from the viewpoint of the viscosity and productivity of the reaction solution. It is preferably 100 parts by mass or less, and more preferably 90 parts by mass or less.

The polymerization temperature is preferably 100 to 200 ° C, more preferably 110 to 180 ° C. When the polymerization temperature is 100 ° C. or higher, the productivity tends to be improved by improving the polymerization rate and lowering the viscosity of the polymerization solution. When the polymerization temperature is 200 ° C. or lower, the polymerization rate can be easily controlled, the formation of by-products can be suppressed, and the coloring of the resin can be suppressed.
From the viewpoint of production efficiency, the polymerization reaction time is preferably 0.5 to 4 hours, more preferably 1.5 to 3.5 hours, and even more preferably 1.5 to 3 hours. The polymerization reaction time in the case of the continuous flow reactor is the average residence time in the reactor.

The polymerization conversion rate in the radical polymerization method is preferably 20 to 80% by mass, more preferably 30 to 70% by mass, and further preferably 35 to 65% by mass. When the polymerization conversion rate is 20% by mass or more, the remaining unreacted monomer can be easily removed, and the appearance of the obtained film tends to be good. When the polymerization conversion rate is 80% by mass or less, the viscosity of the polymerization solution tends to be low and the productivity tends to be improved.
Unless otherwise specified, the polymerization conversion rate in the present invention is measured by the method described in Examples.

The reactor may be either a batch reactor or a continuous flow reactor, and a continuous flow reactor is preferable from the viewpoint of productivity. In the continuous flow reactor, the polymerization reaction raw material is prepared under an inert atmosphere such as nitrogen, the raw material is supplied to the reactor at a constant flow rate, and the liquid in the reactor is withdrawn at a flow rate corresponding to the supplied amount. Examples of the reactor include a tubular reactor that can be brought into a state close to a plug flow and a tank type reactor that can be brought into a state close to complete mixing. The number of reactors may be one or two or more, and it is preferable to employ a continuous flow type tank reactor for at least one reactor. The amount of liquid in the tank reactor at the time of the polymerization reaction is preferably 1/4 to 3/4, more preferably 1/3 to 2/3 with respect to the volume of the tank reactor.
The reactor is usually equipped with a stirrer. Examples of the agitator include a static agitator and a dynamic agitator. Examples of the dynamic agitator include a max blend type agitator, a agitator having a grid-like blade rotating around a vertical rotating shaft arranged in the center, a propeller type agitator, and a screw type agitator. Among them, the Max Blend type agitator is preferable from the viewpoint of uniform mixing.

After completion of the polymerization, if necessary, volatile components such as unreacted monomers are removed. As a removing method, a thermal devolatile method is preferable. Examples of the devolatilization method include a balanced flash method and an adiabatic flash method. The volatilization temperature by the adiabatic flash method is preferably 200 to 280 ° C, more preferably 220 to 260 ° C. The heating time of the resin in the adiabatic flash method is preferably 0.3 to 5 minutes, more preferably 0.4 to 3 minutes, and even more preferably 0.5 to 2 minutes. When devolatile in such a temperature range and heating time, it is easy to obtain a (meth) acrylic resin (A1) with less coloring. The removed unreacted monomer can be recovered and used again in the polymerization reaction. The yellow index of the recovered monomer may be increased by the heat applied during the recovery operation or the like. The recovered monomer is preferably purified by a known method to reduce the yellow index.

Examples of the method for controlling the molecular weight distribution (Mw / Mn) include a controlled polymerization method, and a living radical polymerization method and a living anion polymerization method are preferable. Examples of the living radical polymerization method include atom transfer radical polymerization (ATRP) method, reversible addition fragmentation chain transfer polymerization (RAFT) method, nitroxide-mediated polymerization (NMP) method, boron-mediated polymerization method, and catalytic transfer polymerization (CCT) method. Can be mentioned. As a living anionic polymerization method, an organic alkali metal compound is used as a polymerization initiator and anionic polymerization is carried out in the presence of a mineral salt such as a salt of an alkali metal or an alkaline earth metal (see Japanese Patent Publication No. 7-25859). A method of anionic polymerization using an organoalkali metal compound as a polymerization initiator in the presence of an organoaluminum compound (see JP-A-11-335432) and a method of anionic polymerization using an organic rare earth metal complex as a polymerization initiator (Japanese Patent Laid-Open No. 6). -Refer to Japanese Patent Application Laid-Open No. 93060) and the like.

As the polymerization initiator used in the anion polymerization method, alkyllithium such as n-butyllithium, sec-butyllithium, isobutyllithium, and tert-butyllithium are preferable. From the viewpoint of productivity, it is preferable that the organoaluminum compound coexists. As the organoaluminum compound of the formula: AlR ^A R ^B R ^C A compound represented by (wherein, the R ^A to R ^C are each independently an unsubstituted or alkyl group having a substituent, unsubstituted or substituted Cycloalkyl group with substituents, aryl group with unsubstituted or substituent, aralkyl group with unsubstituted or substituent, alkoxyl group with unsubstituted or substituent, aryloxy group with unsubstituted or substituent or N, N-disubstituted amino group .R ^B and R ^C represents a, these become bonded may be arylenedioxy group having unsubstituted or substituted.) are exemplified.

Organoaluminium compounds include isobutylbis (2,6-di-tert-butyl-4-methylphenoxy) aluminum, isobutylbis (2,6-di-tert-butylphenoxy) aluminum, and isobutyl [2,2'-. Methylenebis (4-methyl-6-tert-butylphenoxy)] aluminum and the like can be mentioned.
In the anionic polymerization method, ether, a nitrogen-containing compound and the like can coexist in order to control the polymerization reaction.

[(Meta) acrylic resin (A2)]
The (meth) acrylic resin (A2) has a syndiotacticity (rr) of 65% or more, preferably 70 to 90%, and more preferably 72 to 85% in triplet display. If the syndiotacticity (rr) is less than 65%, the heat resistance may decrease.

The (meth) acrylic resin (A2) is not particularly limited as long as it is a resin having a structural unit derived from the (meth) acrylic acid ester, but from the viewpoint of heat resistance, it is mainly composed of a methacrylic acid ester monomer unit. Is preferable. Examples of the methacrylic acid ester include alkyl methacrylates such as MMA, ethyl methacrylate, and butyl methacrylate; aryl methacrylates such as phenyl methacrylate; cyclohexyl methacrylate, and cycloalkyl methacrylates such as norbornenyl methacrylate. And so on. Of these, alkyl methacrylate esters are preferred, and MMA is particularly preferred.

The content of the methacrylic acid ester monomer unit in the (meth) acrylic resin (A2) is preferably 90% by mass or more, more preferably 95% by mass or more, and further preferably 98% by mass or more. Yes, more preferably 99% by mass or more, and particularly preferably 100% by mass.
The content of the MMA monomer unit in the (meth) acrylic resin (A2) is preferably 90% by mass or more, more preferably 95% by mass or more, and further preferably 98% by mass or more. Even more preferably, it is 99% by mass or more, and particularly preferably 100% by mass.

The (meth) acrylic resin (A2) may contain one or more monomer units other than the methacrylic acid ester monomer unit. Other monomeric units include acrylic acid alkyl esters such as methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, and 2-ethylhexyl acrylate; acrylic acid aryl esters such as phenyl acrylate; Acrylic acid cycloalkyl esters such as cyclohexyl acrylate and norbornenyl acrylate; aromatic vinyl compounds such as styrene and α-methylstyrene; acrylamide and metaacrylamide; nitriles such as acrylonitrile and metaacrylonitrile, etc. Examples thereof include structural units derived from vinyl-based monomers having only one polymerizable carbon-carbon double bond in one molecule.

The weight average molecular weight (Mw) of the (meth) acrylic resin (A2) is preferably 40,000 to 200,000, more preferably 50,000 to 150,000, and even more preferably 60,000 to 100,000. When Mw is 40,000 or more, the mechanical strength (impact resistance, toughness, etc.) of the obtained film tends to be improved, and when it is 200,000 or less, the (meth) acrylic resin film of the present invention is formed. There is a tendency that the fluidity of the (meth) acrylic resin composition is improved and the moldability is improved.

The molecular weight distribution (Mw / Mn) of the (meth) acrylic resin (A2) represented by the ratio of the weight average molecular weight (Mw) to the number average molecular weight (Mn) is preferably 1.00 to 1.80. , More preferably 1.01 to 1.40, and even more preferably 1.03 to 1.30. When a (meth) acrylic resin (A2) having a molecular weight distribution (Mw / Mn) within such a range is used, the obtained film has excellent mechanical strength. Mw and Mw / Mn can be controlled by adjusting the polymerization method of the (meth) acrylic resin (A2) and the type and / or amount of the polymerization initiator used at the time of production.

The melt flow rate (MFR) of the (meth) acrylic resin (A2) measured under the conditions of a temperature of 230 ° C. and a load of 3.8 kg is preferably 0.1 g / 10 minutes or more, more preferably 0.2. It is ~ 30 g / 10 minutes, more preferably 0.5 to 20 g / 10 minutes, and particularly preferably 1.0 to 15 g / 10 minutes. When the MFR of the (meth) acrylic resin (A2) is 0.1 g / 10 minutes or more, processability can be ensured.

The Tg of the (meth) acrylic resin (A2) is preferably 120 ° C. or higher, more preferably 125 ° C. or higher, and even more preferably 130 ° C. or higher. The upper limit of Tg of the (meth) acrylic resin (A2) is usually 150 ° C.

As a method for producing the (meth) acrylic resin (A2), from the viewpoint of productivity, in the anion polymerization method, the polymerization temperature, the polymerization time, the type and / or amount of the chain transfer agent, the type and / or the polymerization initiator. A method of adjusting the amount or the like is preferable. The details of the anion polymerization method are as described above. For example, by the anion polymerization method at a low temperature, the syndiotacticity (rr) of the triplet display of the (meth) acrylic resin (A2) could be set to 65% or more, and the glass transition temperature was significantly increased. It can be a resin.
The polymerization temperature is preferably -10 to 50 ° C, more preferably 10 to 30 ° C. When the polymerization temperature is within the above range, the syndiotacticity (rr) of the (meth) acrylic resin (A2) in triplet display can be 65% or more.
From the viewpoint of production efficiency, the polymerization reaction time is preferably 0.3 to 5 hours, more preferably 0.5 to 3 hours, and even more preferably 1 to 2 hours.

(Mass ratio)
The mass ratio of the (meth) acrylic resin (A) to the (meth) acrylic resin (A1) / (meth) acrylic resin (A2) is 1/99 to 30/70, preferably 5/95 to It is 27/73, more preferably 10/90 to 25/75, and even more preferably 17/83 to 23/77. If the mass ratio of the (meth) acrylic resin (A1) / (meth) acrylic resin (A2) is less than 1/99, the heat resistance of the obtained film may decrease, and if it is larger than 30/70, it is processed. There is a risk of reduced sex.

<Thermoplastic resin (B)>
The thermoplastic resin (B) contains a polycarbonate (C) and a phenoxy resin (D), and the mass ratio of the polycarbonate (C) / phenoxy resin (D) is preferably 1/99 to 99/1. Is 10/90 to 70/30, more preferably 16/84 to 55/45, and even more preferably 47/53 to 53/47. When the mass ratio of the polycarbonate (C) / phenoxy resin (D) is within the above range, the orientation birefringence of the thermoplastic resin (B) can be within the range described later.

[Polycarbonate (C)]
Examples of the polycarbonate (C) include a polymer obtained by reacting a polyfunctional hydroxy compound with a carbonic acid ester-forming compound. Aromatic polycarbonate is preferable from the viewpoint of compatibility with the (meth) acrylic resin (A) and the transparency of the obtained film.

Polycarbonate (C) has a melt volume measured under the conditions of 300 ° C. and 1.2 kg load from the viewpoint of compatibility with the (meth) acrylic resin (A), transparency of the obtained film, surface smoothness, and the like. flow rate (MVR) is preferably 1 to 100 cm ^3/10 min, more preferably from 5~80cm ^3/10 min, more preferably from 20 to 50 cm ^3/10 min.
The MVR can be measured under the above conditions according to JIS K7210-1: 2014.

Polycarbonate (C) has a polystyrene-equivalent Mw of preferably 1500 to 40,000 from the viewpoint of compatibility with the (meth) acrylic resin (A), transparency of the obtained film, surface smoothness, and the like. It is preferably 18,000 to 38,000, and more preferably 2000 to 36,000.
Further, the molecular weight distribution (Mw / Mn) of the polycarbonate (C) represented by the ratio of the weight average molecular weight (Mw) to the number average molecular weight (Mn) is preferably 1.2 to 4. from the viewpoint of processability. It is 0, more preferably 1.5 to 3.0, and even more preferably 1.7 to 2.5.
The MVR, Mw and (Mw / Mn) of the polycarbonate (C) can be controlled by adjusting the amount of terminal terminator and / or branching agent.

The Tg of the polycarbonate (C) is higher than the Tg of the (meth) acrylic resin (A), preferably 130 ° C. or higher, more preferably 135 ° C. or higher, and further preferably 140 ° C. or higher. The upper limit of Tg of polycarbonate (C) in the present invention is usually 180 ° C.

Examples of the method for producing polycarbonate (C) include a phosgene method (interfacial polymerization method) and a melt polymerization method (transesterification method). Aromatic polycarbonate can be produced by subjecting a polycarbonate raw material produced by a melt polymerization method to a treatment for adjusting the amount of terminal hydroxy groups.

Polycarbonate (C) may contain other structural units such as polyester, polyurethane, polyether, or polysiloxane in addition to the polycarbonate structural unit.

[Phenoxy resin (D)]
The phenoxy resin (D) is a thermoplastic polyhydroxypolyester resin. The phenoxy resin (D) preferably contains 50% by mass or more of one or more structural units represented by the following general formula (1).

In the above general formula (1), X is a divalent group containing at least one benzene ring, and R ¹ is a linear or branched alkylene group having 1 to 6 carbon atoms. The structural units represented by the general formula (1) may be connected in any form of random, alternating, or block.
The phenoxy resin (D) preferably contains 10 to 1000 structural units represented by the general formula (1), more preferably 15 to 500, and even more preferably 30 to 300.
In addition, in this specification, "*" means a combiner.

It is preferable that X in the general formula (1) is a divalent group derived from the compounds represented by the following general formulas (2) to (4). The positions of the two bonds constituting the divalent group are not particularly limited as long as they are chemically possible positions. X in the general formula (1) may be a divalent group having two bonds formed by extracting two hydrogen atoms from the benzene ring in the compounds represented by the general formulas (2) to (4). preferable. In particular, it is preferable that the divalent group has two bonds formed by extracting one hydrogen atom from each of any two benzene rings in the compounds represented by the general formulas (3) and (4).

In the above general formula (2), R ² is a hydrogen atom, a linear or branched alkyl group having 1 to 6 carbon atoms, or a linear or branched alkenyl group having 2 to 6 carbon atoms. If R ² there are a plurality, may be different in each of a plurality of R ² are the same. p is an integer of 1 to 4.

In the above general formula (3), R ³ is a single bond, a linear or branched alkylene group having 1 to 6 carbon atoms, a cycloalkylene group having 3 to 20 carbon atoms, or a cycloalkylidene group having 3 to 20 carbon atoms. Is. In the above general formulas (3) and (4), R ⁴ and R ⁵ are independently hydrogen atoms, linear or branched alkyl groups having 1 to 6 carbon atoms, or linear or branched chain having 2 to 6 carbon atoms, respectively. It is an alkenyl group of a branched chain. If R ⁴ and ^{R 5} there are a plurality, the plurality of ^{R 4} and ^{R 5,} may each be the same or different. n and m are each independently an integer of 1 to 4.

In the above general formula (1), X may be a divalent group derived from a compound formed by condensing a plurality of benzene rings with an alicyclic or a heterocycle. For example, a divalent group derived from a compound having a fluorene structure or a carbazole structure can be mentioned.

The structural unit represented by the general formula (1) is preferably a structural unit represented by the following general formulas (5) and (6), and more preferably a structural unit represented by the following general formula (7). .. The phenoxy resin (D) preferably contains 10 to 1000 such structural units.

In the above general formula (5), R ⁶ is a single bond, a linear or branched alkylene group having 1 to 6 carbon atoms, a cycloalkylene group having 3 to 20 carbon atoms, or a cycloalkylidene group having 3 to 20 carbon atoms. Is. In the general formulas (5) and (6), R ⁷ is a linear or branched alkylene group having 1 to 6 carbon atoms.

The phenoxy resin (D) preferably does not have an epoxy group at the terminal because it is easy to obtain a film having few gel defects.

The polystyrene-equivalent Mw of the phenoxy resin (D) is preferably 3000 to 2000000, more preferably 5000 to 100000, and even more preferably 1000 to 50000. When Mw is in the range, a (meth) acrylic resin composition having high heat resistance and high strength can be obtained.
Further, the molecular weight distribution (Mw / Mn) of the phenoxy resin (D) represented by the ratio of the weight average molecular weight (Mw) and the number average molecular weight (Mn) is preferable from the viewpoint of the balance between heat resistance and processability. Is 1.1 to 4.0, more preferably 1.5 to 3.5, and even more preferably 2.0 to 3.0.

The Tg of the phenoxy resin (D) is lower than that of the (meth) acrylic resin (A), preferably 80 ° C. or higher, more preferably 90 ° C. or higher, and further preferably 95 ° C. or higher. When the Tg of the phenoxy resin (D) is 80 ° C. or higher, the heat resistance of the (meth) acrylic resin composition is improved. The upper limit of Tg of the phenoxy resin (D) in the present invention is preferably 150 ° C. When the Tg of the phenoxy resin (D) is 150 ° C. or lower, the hardness of the obtained film can be increased.

The phenoxy-based resin (D) can be obtained, for example, from a condensation reaction between a divalent phenol compound and epihalohydrin, or a double addition reaction between a divalent phenol compound and a bifunctional epoxy resin. This reaction can be carried out without solvent or in solvent.

Examples of the divalent phenol compound include hydroquinone, resorcin, 4,4-dihydroxybiphenyl, 4,4'-dihydroxydiphenylketone, 2,2-bis (4-hydroxyphenyl) propane, and 1,1-bis (4-hydroxyphenyl). ) Cyclohexane, 1,1-bis (4-hydroxyphenyl) -3,3,5-trimethylcyclohexane, bis (4-hydroxyphenyl) methane, 1,1-bis (4-hydroxyphenyl) ethane, 2,2- Bis (4-hydroxyphenyl) butane, 1,1-bis (4-hydroxyphenyl) -1-phenylethane, bis (4-hydroxyphenyl) diphenylmethane, 2,2-bis (4-hydroxy-3-methylphenyl) Propane, 2,2-bis (3-phenyl-4-hydroxyphenyl) propane, 2,2-bis (4-hydroxy-3-tert-butylphenyl) propane, 1,3-bis (2- (4-hydroxy) Phenyl) propyl) benzene, 1,4-bis (2- (4-hydroxyphenyl) propyl) benzene, 2,2-bis (4-hydroxyphenyl) -1,1,1-3,3,3-hexafluoro Examples thereof include propane and 9,9'-bis (4-hydroxyphenyl) fluorene. Among them, 4,4-dihydroxybiphenyl, 4,4'-dihydroxydiphenylketone, 2,2-bis (4-hydroxyphenyl) propane, and 9,9'-bis (4-hydroxyphenyl) from the viewpoint of physical properties and cost. Fluorene is preferred.

Examples of the bifunctional epoxy resins include epoxy oligomers obtained by a condensation reaction between the above divalent phenol compound and epihalohydrin. Specifically, hydroquinone diglycidyl ether, resorcin diglycidyl ether, bisphenol S type epoxy resin, bisphenol A type epoxy resin, bisphenol F type epoxy resin, methylhydroquinone diglycidyl ether, chlorohydroquinone diglycidyl ether, 4,4'-. Dihydroxydiphenyl oxide diglycidyl ether, 2,6-dihydroxynaphthalenediglycidyl ether, dichlorobisphenol A diglycidyl ether, and tetrabromobisphenol A type epoxy resin, 9,9'-bis (4-hydroxyphenyl) full orange glycidyl ether, etc. Can be mentioned. Among them, bisphenol A type epoxy resin, bisphenol S type epoxy resin, hydroquinone diglycidyl ether, bisphenol F type epoxy resin, tetrabromobisphenol A type epoxy resin, and 9,9'-bis (4-hydroxy) from the viewpoint of physical properties and cost. Phenyl) full orange glycidyl ether is preferred.

Examples of the solvent used for producing the phenoxy resin (D) include aprotic organic solvents such as methyl ethyl ketone, dioxane, tetrahydrofuran, acetophenone, N-methylpyrrolidone, dimethyl sulfoxide, N, N-dimethylacetamide, and sulfolane. ..
Examples of the catalyst used for producing the phenoxy resin (D) include alkali metal hydroxides, tertiary amine compounds, quaternary ammonium compounds, tertiary phosphine compounds, and quaternary phosphonium compounds.

Commercially available phenoxy resins (D) include YP-50 and YP-50S manufactured by Nippon Steel & Sumikin Chemical Co., Ltd., jER (registered trademark) series manufactured by Mitsubishi Chemical Corporation, PKFE and PKHJ manufactured by InChem, etc. Can be mentioned.

The photoelastic modulus of the thermoplastic resin (B) is preferably 67 × 10 ^{-12 to} 90 × ^10-12 Pa ^-1 , and more preferably 67 × 10 ^{-12 to} 85 × 10 ^-12 Pa ^-1 . , More preferably 67 × 10 ^-12 to 80 × 10 ^-12 Pa ^-1 . When the photoelastic coefficient of the thermoplastic resin (B) is 67 × 10 ^-12 Pa ^-1 or more, the amount of resin used for adjusting the phase difference can be suppressed, and at 90 × 10 ^-12 Pa ^-1 or less. This makes it easy to adjust the phase difference.
In the present specification, the photoelastic modulus means that birefringence occurs according to the stress when stress is applied at a temperature lower than the glass transition temperature of the resin and the resin is slightly deformed. The ratio of this stress to birefringence is defined as light. Let it be the elastic modulus. Unless otherwise specified, the photoelastic modulus in the present invention is measured and calculated by the method described in Examples.
Examples of the method for adjusting the photoelastic coefficient of the thermoplastic resin (B) include a method of mixing two or more types of polycarbonate (C) and a phenoxy resin (D) having different glass transition temperatures.

The orientation birefringence of the thermoplastic resin (B) is preferably 80 × 10 ^{-4 to} 160 × 10 ^-4 , more preferably 85 × 10 ^{-4 to} 140 × 10 ^-4 , and even more preferably. It is 85 × 10 ^{-4 to} 135 × 10 ^-4 . When the orientation birefringence of the thermoplastic resin (B) is 80 × 10 ^-4 or more, the amount of resin used for adjusting the phase difference can be suppressed, and when it is 160 × 10 ^-4 or less, the phase difference Adjustment can be facilitated.
In the present specification, the orientation birefringence is a birefringence caused by the orientation of the resin, and unless otherwise specified in the present specification, the birefringence that occurs when 100% stretched at a glass transition temperature of + 10 ° C. Refraction is defined as orientation birefringence. The orientation birefringence in the present invention is measured and calculated by the method described in Examples unless otherwise specified.
As a method for adjusting the orientation birefringence of the thermoplastic resin (B), for example, a method of mixing two or more types of polycarbonate (C) and a phenoxy resin (D) having different glass transition temperatures, or a method of mixing the polycarbonate (C) Examples thereof include a method of adjusting the mixing ratio of the phenoxy resin (D).

The (meth) acrylic resin film of the present invention contains 1 to 5 parts by mass of the thermoplastic resin (B) with respect to 100 parts by mass of the (meth) acrylic resin (A), and is preferable from the viewpoint of low phase difference. Contains 2 to 4 parts by mass, more preferably 2.5 to 4 parts by mass. If the content of the thermoplastic resin (B) is less than 1 part by mass, the absolute value of the phase difference may increase, and if it exceeds 5 parts by mass, the physical properties such as optical characteristics and thermal characteristics may deteriorate. There is.

Further, the content of the polycarbonate (C) in the thermoplastic resin (B) is preferably 10 to 70% by mass, more preferably 30 to 70% by mass, from the viewpoint of molding stability. When the molding stability is good, for example, in the film stretching step, even if temperature unevenness occurs in the width direction, the difference in physical properties due to temperature becomes small, and the physical properties of the obtained film in the width direction become uniform.

It is considered that the relaxation behavior of each resin in the film stretching step is related to the reason why the molding stability is improved when the content of the polycarbonate (C) in the thermoplastic resin (B) is within the above range. Be done. A resin having a low glass transition temperature is easy to relax even when stretched in a temperature range suitable for the stretching temperature of the matrix (meth) acrylic resin (A), so that birefringence due to orientation is unlikely to occur, and the stretching temperature can be changed. However, the effect on the phase difference of the film is small. On the other hand, a resin having a high glass transition temperature is difficult to relax even after stretching, and birefringence due to orientation increases the influence of the stretching temperature on the film phase difference. That is, the polycarbonate (C) has a large temperature dependence in the stretching step with respect to the phase difference of the film, and the phenoxy resin (D) has a small temperature dependence. By containing the polycarbonate (C) within the above range, the phase difference of the film can be reduced, and the temperature dependence of the stretching step on the phase difference of the film, that is, the change in the phase difference of the film due to the stretching temperature can be reduced. it can.

The content of the phenoxy resin (D) in the thermoplastic resin (B) is preferably 30 to 90% by mass, more preferably 30 to 70% by mass, from the viewpoint of adjusting the phase difference.

From the viewpoint of low phase difference, the photoelastic modulus of the (meth) acrylic resin composition constituting the (meth) acrylic resin film of the present invention is preferably 4.0 × 10 ^{-12 to 0} Pa ^-1. , -3.7 × 10 ^{-12 to 0} Pa ^-1 is more preferable. Further, the orientation birefringence of the (meth) acrylic resin composition is preferably -1 × 10 ^{-4 to} 0.5 × 10 ^-4 from the viewpoint of low phase difference, and is preferably −0.4 × 10 ^-4. More preferably, it is ~ 0.5 × 10 ^-4 .

The Tg of the (meth) acrylic resin composition constituting the (meth) acrylic resin film of the present invention is preferably 100 ° C. or higher, more preferably 105 ° C. or higher, and further preferably 110 ° C. or higher.

<Other optional ingredients>
The (meth) acrylic resin composition constituting the (meth) acrylic resin film of the present invention may contain other optional components, if necessary, as long as the effects of the present invention are not impaired. Other optional components include polymers, polymer processing aids, antioxidants, thermal degradation inhibitors, UV absorbers, light stabilizers, lubricants, mold release agents, antistatic agents, flame retardants, dye pigments, and light. Various additives such as diffusers, organic pigments, matting agents, impact resistance modifiers, impact resistance aids, fatty alcohols, heat stabilizers, foaming agents, fillers, softeners, plasticizers and phosphors Can be mentioned. The total amount of these various additives is preferably 7 parts by mass or less, more preferably 5 parts by mass or less, based on 100 parts by mass of the total amount of the (meth) acrylic resin (A) and the thermoplastic resin (B). It is more preferably 4 parts by mass or less.
From the viewpoint of mechanical properties and surface hardness of the (meth) acrylic resin film of the present invention, it is preferable not to add a large amount of foaming agent, filler, matting agent, light diffusing agent, softening agent, and plasticizer.

<Other polymers>
Other polymers include elastomer resins such as polyethylene, polypropylene, polybutene-1, poly-4-methylpentene-1, and polynorbornene; ethylene-based ionomers; polystyrene, high-impact polystyrene, AS resin, ABS resin, AES resin. , AAS resin, ACS resin, and styrene resin such as MBS resin; ester resin such as polyethylene terephthalate and polyvinyl terephthalate; amide resin such as nylon 6, nylon 66, and polyamide elastomer; polyvinyl chloride, polyvinylidene chloride. , Polyfluoride vinylidene, polyvinyl alcohol, polyvinyl butyral, polyvinyl acetal, polyvinyl phenol, and ethylene-vinyl alcohol copolymer; polyacetal; polyurethane; modified polyphenylene ether and polyphenylene sulfide; silicone modified resin; acrylic rubber, acrylic thermoplastic elastomer, And silicone rubbers; styrene-based thermoplastic elastomers such as SEPS, SEBS, and SIS; olefin-based rubbers such as IR, EPR, and EPDM. The amount of other polymers in the (meth) acrylic resin composition constituting the (meth) acrylic resin film of the present invention is the total amount of the (meth) acrylic resin (A) and the thermoplastic resin (B). It is preferably 20 parts by mass or less, more preferably 15 parts by mass or less, and further preferably 10 parts by mass or less with respect to 100 parts by mass.

<Polymer processing aid>
As the polymer processing aid, polymer particles (non-crosslinked rubber particles) having a particle size of 0.05 to 0.5 μm, which can be produced by an emulsion polymerization method, can be used. The polymer particles may be single-layer particles composed of polymers having a single composition and a single ultimate viscosity, or may be two or more layers of multilayer particles composed of two or more kinds of polymers having different compositions or extreme viscosities. You may. Among them, particles having a two-layer structure having a polymer layer having a low ultimate viscosity in the inner layer and a polymer layer having a high ultimate viscosity of 5 dl / g or more in the outer layer are preferable. From the viewpoint of moldability, the polymer processing aid preferably has an ultimate viscosity of 3 to 6 dl / g.
Specific examples of the polymer processing aid include Metabrene (registered trademark) -P series manufactured by Mitsubishi Chemical Corporation and Pararoid (registered trademark) series manufactured by Dow Chemical Corporation.

The content of the polymer processing aid is preferably 0.1 to 5 parts by mass with respect to 100 parts by mass of the total amount of the (meth) acrylic resin (A) and the thermoplastic resin (B). When the content of the polymer processing aid is 0.1 parts by mass or more, good processing characteristics are obtained, and when it is 5 parts by mass or less, the appearance of the obtained film is good.

The content of the (meth) acrylic resin (A) in the (meth) acrylic resin composition constituting the (meth) acrylic resin film of the present invention is preferably 80 to 99.5% by mass, and more. It is preferably 85 to 99.4% by mass, more preferably 87 to 99.3% by mass, and particularly preferably 90 to 99.2% by mass.
Further, the content of the thermoplastic resin (B) in the (meth) acrylic resin composition constituting the (meth) acrylic resin film of the present invention is preferably 0.5 to 5% by mass, more preferably. Is 0.6 to 4.8% by mass, more preferably 0.7 to 4.5% by mass.

(the film)
The (meth) acrylic resin film of the present invention can be obtained by molding (forming) the above-mentioned (meth) acrylic resin composition.
The phase difference in the thickness direction of the (meth) acrylic resin film of the present invention is −5 to 5 nm, preferably -4 to 4 nm, and more preferably −3.5 to 3.5 nm.

The phase difference in the thickness direction of the film can be measured by the measurement method shown below.
(1) A 40 mm × 30 mm × 0.04 mm test piece is set in an automatic birefringence meter (for example, “KOBRA-WR” manufactured by Oji Measurement Co., Ltd.), and the temperature is 23 ± 2 ° C. and the humidity is 50 ± 5%. The phase difference in the 40 ° tilt direction is measured under the condition that the wavelength of the measurement light is 590 nm.
(2) The refractive indexes n _x , n _y , and n _z are calculated from the above values and the average refractive index n, and the phase difference Rth in the thickness direction (= ((n _x + n _y ) / 2- _nz ) × d) Is calculated.
In addition, n _x is the refractive index in the in-plane slow-phase axis direction, n _y is the refractive index in the in-plane slow-phase axis orthogonal direction, n _z is the refractive index in the thickness direction, and d is the thickness [nm] of the test piece. is there.
The thickness d [nm] and the refractive index of the test piece can be measured using a thickness gauge and a refractometer (for example, "Digimatic Indicator" manufactured by Mitutoyo Co., Ltd.), and the average refractive index n is , Digital precision refractometer (for example, "KPR-20" manufactured by Carnew Optical Industry Co., Ltd.) can be used for measurement.

The haze of the (meth) acrylic resin film of the present invention is 0.2% or less, preferably 0.16% or less, and more preferably 0.13% or less.
The haze of the film can be measured according to JIS K7136: 2000.

In the (meth) acrylic resin film of the present invention, the ratio of the tear strength in the longitudinal direction (MD) to the tear strength in the width direction (TD) measured in accordance with JIS K7128-1: 1998 is preferably 0. It is 9 to 1.1, more preferably 0.95 to 1.05. The tear strength ratio can be adjusted according to the type and / or composition ratio of the resin used.

The (meth) acrylic resin film of the present invention preferably does not contain a block copolymer as the (meth) acrylic resin (A).

(Film original)
The method for producing the raw film is not particularly limited, and the film can be formed by melt-forming or solution-forming, but from the viewpoint of productivity, melt-forming is preferable. Examples of the melt film forming include an inflation method, a T-die method, a calendar method, a cutting method, and the like, and the T-die method can be particularly preferably adopted. An extruder type melt extruder equipped with a single-screw or twin-screw extrusion screw can be used for the melt-forming film. The melt extrusion temperature is preferably 150 to 350 ° C, more preferably 200 to 300 ° C. Further, when melt-kneading using a melt extrusion device, it is preferable to perform melt-kneading using a vent under reduced pressure or under a nitrogen stream from the viewpoint of suppressing coloring. Further, from the viewpoint of removing foreign substances, it is preferable to install a polymer filter for manufacturing. Further, in order to improve the thickness accuracy, it is advisable to install and manufacture a gear pump.
The film obtained by the above manufacturing method is used as the original film.

When the physical properties of the present invention are satisfied without stretching the original film, the original film can be the (meth) acrylic resin film of the present invention. It is also possible to obtain the (meth) acrylic resin film of the present invention by means other than stretching such as heat treatment and energy ray irradiation.

The film raw material manufacturing step and the biaxial stretching step may be carried out continuously or discontinuously.

The thickness of the original film is not particularly limited, and is preferably 10 to 500 μm, more preferably 20 to 200 μm, and even more preferably 30 to 100 μm.
The thickness distribution of the film is usually within ± 10%, preferably within ± 5%, and more preferably within ± 3% with respect to the average value. If the thickness distribution exceeds ± 10%, stretching unevenness may easily occur due to stress concentration in a portion having a thin film thickness when the stretching treatment is performed.

(Stretched film)
The stretched film of the present invention can be obtained from the above-mentioned film raw fabric. The heat resistance and mechanical strength of the film can be improved by the stretching treatment. The stretching method in the stretching step is not particularly limited, and examples thereof include a sequential biaxial stretching method, a simultaneous biaxial stretching method, and a tuber stretching method. The stretching treatment is composed of a preheating step, a stretching step, and a heat fixing step, and a relaxation step may be performed after the heat fixing step.

In the case of the sequential biaxial stretching method, the stretching speed may be the same or different in each stretching direction. The stretching speed is preferably 100 to 5000% / min, more preferably 100 to 3000% / min. Further, in the case of the simultaneous biaxial stretching method, if the stretching speed is increased, tearing is likely to occur and the productivity is significantly reduced. Therefore, the stretching speed is preferably 50 to 5000% / min, and 100 to 3000% / min. Is more preferable.

The stretching temperature is preferably Tg to (Tg + 30 ° C.), more preferably (Tg + 5 ° C.) to (Tg + 25 ° C.) in any of the sequential / simultaneous biaxial stretching methods based on Tg of the (meth) acrylic resin composition. ). In such a range, thickness unevenness tends to be suppressed. Film breakage can be suppressed when the stretching temperature is Tg or higher of the (meth) acrylic resin composition, and thermal properties can be improved by Tg + 30 ° C. or lower of the (meth) acrylic resin composition. it can.

The draw ratio in each axial direction (area ratio of the stretched film with respect to the unstretched film) is preferably 1.01 to 12.25 times, more preferably 1.10 to 9 times. When the draw ratio is within the above range, the mechanical strength of the film can be improved.

The (meth) acrylic resin film of the present invention includes the above-mentioned unstretched and stretched ones. The (meth) acrylic resin film of the present invention may have an arbitrary layer such as various functional layers laminated on at least one surface thereof. Examples of the functional layer include a hard coat layer, an anti-glare layer, an anti-reflection layer, an anti-sticking layer, a diffusion layer, an anti-glare layer, an anti-static layer, an anti-fouling layer, an adhesive layer, and an easy-to-slip layer containing fine particles and the like. Be done.

The (meth) acrylic resin film of the present invention includes a polarizer protective film, a retardation film, a liquid crystal protective film, a surface material of a portable information terminal, a display window protective film of a portable information terminal, a light guide film, a silver nanowire or the like. It is suitable for a transparent conductive film on which carbon nanotubes are coated on the surface, a front film of various displays, and the like, and is particularly suitable for a polarizer protective film and the like.
In addition, the (meth) acrylic resin film of the present invention includes IR (infrared) cut film, security film, shatterproof film, decorative film, metal decorative film, back sheet of solar cell, front sheet for flexible solar cell. , Shrink film, in-mold label film, gas barrier film and the like. It is also suitable for optical films for organic electroluminescence (EL) lighting equipment.

One aspect of the polarizing plate according to the (meth) acrylic resin film of the present invention is a polarizing element protective film composed of a polarizing element and the above-mentioned (meth) acrylic resin film of the present invention laminated on at least one surface thereof. And have. In the embodiment in which the (meth) acrylic resin film of the present invention is laminated on one surface of the polarizer, any optical other than the (meth) acrylic resin film of the present invention is required on the other surface of the polarizer. The film can be laminated. Examples of the optional optical film include a polarizer protective film other than the (meth) acrylic resin film of the present invention, a viewing angle adjusting film, a retardation film, a brightness improving film, and the like. Lamination can be done via an adhesive layer, if desired.

The polarizing plate of the above aspect can be used in an image display device. Examples of the image display device include a self-luminous display device such as an (organic) electroluminescence display (ELD), a plasma display (PD), and a field emission display (FED); a liquid crystal display device (LCD) and the like. Be done. The LCD has a liquid crystal cell and a polarizing plate arranged on at least one side thereof.

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples. The present invention is not limited to the following examples. In addition, the present invention includes all aspects in which the above-mentioned matters representing technical features such as characteristic values, forms, manufacturing methods, and uses are arbitrarily combined.

<Evaluation items and evaluation methods>
The evaluation items and evaluation methods are as follows.
<Polymerization conversion rate>
GL Sciences Inc. was used as a column on a gas chromatograph GC-14A manufactured by Shimadzu Corporation. Inert CAP 1 (df = 0.4 μm, ID = 0.25 mm, length = 60 m) manufactured by Inert CAP 1 was connected. The injection temperature was 180 ° C. and the detector temperature was 180 ° C. The column temperature was maintained at 60 ° C. for 5 minutes, then raised from 60 ° C. to 200 ° C. at a heating rate of 10 ° C./min, and held at 200 ° C. for 10 minutes. The measurement was performed under the above conditions, and the polymerization conversion rate (mass%) was calculated by (polymerization conversion rate) = (monomer consumption amount) ÷ (monomer charge amount) × 100 based on the obtained results.

<Weight average molecular weight (Mw), molecular weight distribution (Mw / Mn)>
A sample solution was prepared by dissolving 4 mg of the resin to be measured in 5 ml of tetrahydrofuran (THF) and filtering with a filter having a pore size of 0.1 μm. As the GPC apparatus, "HLC-8320" manufactured by Tosoh Corporation equipped with a differential refractive index detector (RI detector) was used. As the column, two "TSKgel Super Multipore HZM-M" manufactured by Tosoh Corporation and "Super HZ4000" were connected in series. Tetrahydrofuran (THF) was used as the eluent. The temperature of the column oven was set to 40 ° C., the eluent flow rate was 0.35 ml / min, 20 μl of the sample solution was injected into the apparatus, and the chromatogram was measured. The chromatogram is a chart in which the electric signal value (intensity Y) derived from the difference in refractive index between the sample solution and the reference solution is plotted against the retention time X.
GPC measurement was performed using 10 standard polystyrenes having a molecular weight in the range of 400 to 500000, and a calibration curve showing the relationship between the retention time and the molecular weight was prepared. Based on this calibration curve, Mw and Mw / Mn of the resin to be measured were determined. The chromatogram baseline is the point where the slope of the peak on the high molecular weight side of the GPC chart changes from zero to positive when viewed from the side with the earlier retention time, and the slope of the peak on the low molecular weight side is the one with the earlier retention time. It is a line connecting the points that change from minus to zero when viewed from. If the chromatogram shows multiple peaks, the line connecting the point where the slope of the peak on the highest molecular weight side changes from zero to plus and the point where the slope of the peak on the lowest molecular weight side changes from minus to zero It was the baseline.

<Shinji Ikari City (rr) with triplet display>
^{1 1} H-NMR measurement was carried out for the resin to be measured. As a measuring device, a nuclear magnetic resonance device (“ULTRA SHIELD 400 PLUS” manufactured by Bruker) was used. 1 mL of deuterated chloroform was used as the deuterated solvent with respect to 10 mg of the sample. The measurement temperature was room temperature (20 to 25 ° C.), and the number of integrations was 64 times. The area (X) of the region of 0.6 to 0.95 ppm and the area (Y) of the region of 0.6 to 1.35 ppm when the reference substance (TMS) is 0 ppm are measured, and the following formula (1) is used. The value calculated by the above was taken as the syndio tacticity (rr) (%) of the triplet display.
(X / Y) x 100 (%) (1)

<Glass transition temperature>
The glass transition temperature was measured according to JIS K7121: 2012. Using a differential scanning calorimetry device (“DSC-50” manufactured by Shimadzu Corporation), the sample is once heated to 230 ° C. and cooled to 30 ° C. or lower, and then again from 30 ° C. to 230 ° C. at 10 ° C./ The DSC curve was measured under the condition that the temperature was raised at the rate of temperature rise of 1 minute. The intermediate point glass transition temperature obtained from the obtained DSC curve was defined as the glass transition temperature.

<Photoelastic modulus>
The resin composition or thermoplastic resin (B) obtained by the method described later is press-molded to prepare a test piece having a thickness of 20 mm × 40 mm × 1 mm, the sample is pulled with a tensioning jig, and the sample is subjected to stress. Birefringence was measured using a refringence measuring device (WPA-100, manufactured by Photonic Lattice Co., Ltd.), and calculated by photoelastic coefficient (Pa ^-1 ) = (birefringence) / (stress).

<Orientation birefringence>
The resin composition or thermoplastic resin (B) obtained by the method described below is press-molded to prepare a test piece having a thickness of 20 mm × 4 mm × 1 mm, and a tensile tester (manufactured by Shimadzu Corporation, Autograph) is used. A sample for measurement was prepared by pulling the sample at a gripping distance of 20 mm, a tensile speed of 3 mm / min, and a stretching ratio of 100% in an atmosphere of a glass transition temperature of plus 10 ° C. The orientation birefringence of the obtained sample was measured using a birefringence measuring device (WPA-100, manufactured by Photonic Lattice Co., Ltd.).

<Tear strength ratio>
A 150 mm × 50 mm × 0.04 mm test piece was cut out from the film to be measured so that the MD direction was the longitudinal direction, and used as a test piece for measuring the tear strength in the MD direction. Further, a 150 mm × 50 mm × 0.04 mm test piece was cut out so that the TD direction was the longitudinal direction, and used as a test piece for measuring the tear strength in the TD direction. For each test piece, the tear strength was measured under the condition of a test speed of 200 mm / min using a tensile tester (manufactured by Shimadzu Corporation, a desktop tensile tester) in accordance with JIS K7128-1: 1998. The ratio of the tear strength in the MD direction to the tear strength in the TD direction obtained was defined as the tear strength ratio.

<Phase difference>
A test piece having a size of 40 mm × 30 mm × 0.04 mm was cut out from a biaxially stretched film prepared at a stretching temperature of 140 ° C. This test piece was set in an automatic birefringence meter (“KOBRA-WR” manufactured by Oji Measurement Co., Ltd.). The phase difference in the 40 ° tilt direction was measured under the conditions of a temperature of 23 ± 2 ° C., a humidity of 50 ± 5%, and a wavelength of the measurement light of 590 nm. From this value and the average refractive index n, the refractive indexes n _x , n _y , and n _z were calculated, and the phase difference Rth in the thickness direction (= ((n _x + n _y ) /2- _nz ) × d) was calculated. .. In addition, n _x is the refractive index in the in-plane slow-phase axis direction, n _y is the refractive index in the in-plane slow-phase axis orthogonal direction, n _z is the refractive index in the thickness direction, and d is the thickness [nm] of the test piece. is there. The thickness d [nm] of the test piece was measured using a digital indicator (manufactured by Mitutoyo Co., Ltd.). The average refractive index n was measured using a digital precision refractometer (“KPR-20” manufactured by Carnew Optical Industry Co., Ltd.).
Further, the phase difference was calculated for the biaxially stretched film produced at a stretching temperature of 145 ° C. by the same operation as described above.
Further, from the retardation Rth ₁₄₀ of the biaxially stretched film produced at the stretching temperature of 140 ° C. obtained above and the retardation Rth ₁₄₅ of the biaxially stretched film produced at the stretching temperature of 145 ° C., the thickness direction of the biaxially stretched film The absolute value of the difference in phase difference was calculated as ΔRth.

<Total light transmittance>
The total light transmittance of the film was measured using a haze meter (HM-150, manufactured by Murakami Color Research Institute Co., Ltd.) in accordance with JIS K7361-1: 1997.

<Haze>
The haze of the film was measured using a haze meter (HM-150, manufactured by Murakami Color Research Institute Co., Ltd.) in accordance with JIS K7136: 2000.

<Trimming property>
When the film to be measured was cut linearly with scissors, the presence or absence of cracks and cracks was visually confirmed. The case where no crack or crack was confirmed was marked with "○", and the case where crack or crack was confirmed was marked with "x".

<Manufacturing Example 1> (Manufacturing of (meth) acrylic resin (A-1))
The inside of the autoclave equipped with the stirrer and the sampling tube was replaced with nitrogen. To this, 100 parts by mass of purified MMA, 0.0054 parts by mass of 2,2'-azobis (2-methylpropionitrile) (hydrogen extraction capacity: 1%, 1-hour half-life temperature: 83 ° C.), and n-. 0.200 parts by mass of octyl mercaptan was added and stirred to obtain a raw material solution. Nitrogen was sent into this raw material liquid to remove dissolved oxygen.
The above raw material liquid was put into a tank reactor connected to the autoclave by piping up to 2/3 of the capacity. While the temperature was maintained at 140 ° C., the polymerization reaction was first started by a batch method. When the polymerization conversion rate reaches 55% by mass, the raw material liquid is supplied from the autoclave to the tank reactor at a flow rate with an average residence time of 150 minutes while maintaining the temperature at 140 ° C., and at the same time, it corresponds to the supply flow rate of the raw material liquid. The reaction solution was withdrawn from the tank reactor at the desired flow rate, and the polymerization reaction was switched to the continuous flow method. After switching, the polymerization conversion rate in the steady state was 48% by mass.
The reaction solution extracted from the tank reactor in a steady state was supplied to a multi-tube heat exchanger having an internal temperature of 230 ° C. at a flow rate having an average residence time of 2 minutes for heating. Next, the heated reaction solution was introduced into a flash evaporator to remove volatile components containing unreacted monomers as a main component to obtain a molten resin. The molten resin from which the volatile matter has been removed is supplied to a twin-screw extruder having an internal temperature of 260 ° C., discharged in a strand shape, and cut with a pelletizer to obtain a pellet-shaped (meth) acrylic resin (A-1). It was.
The (meth) acrylic resin (A-1) has an Mw of 112000, a Mw / Mn of 1.86, a syndiotacticity (rr) of 52%, a glass transition temperature of 120 ° C., and a single MMA mass. The content of the body unit was 100% by mass (methyl polymethacrylate (PMMA)).

<Manufacturing Example 2> (Manufacturing of (meth) acrylic resin (A-2))
The inside of the autoclave equipped with the stirring blade and the three-way cock was replaced with nitrogen. To this, at room temperature (25 ° C.), a toluene solution of 1600 kg of toluene, 80 kg of 1,2-dimethoxyethane, and 0.45 M concentration of isobutylbis (2,6-di-tert-butyl-4-methylphenoxy) aluminum. A solution of 73.3 kg (42.3 mol) and sec-butyllithium having a concentration of 1.3 mol / L (solvent: 95% by mass of cyclohexane / 5% by mass of n-hexane) was charged at 8.44 kg (14.1 mmol). While stirring, 550 kg of distilled and purified MMA was added dropwise to this at 15 ° C. over 30 minutes. After completion of the dropping, the mixture was stirred at 15 ° C. for 90 minutes. The color of the solution changed from yellow to colorless. The polymerization conversion rate of MMA at this time was 100% by mass. 1500 kg of toluene was added to the obtained solution for dilution. The diluent was then poured into a large amount of methanol to give a precipitate. The obtained precipitate was dried at 80 ° C. and 140 Pa for 24 hours to obtain a (meth) acrylic resin (A-2).
The (meth) acrylic resin (A-2) has a Mw of 70,000, a Mw / Mn of 1.06, a syndiotacticity (rr) of 75%, a glass transition temperature of 132 ° C., and a single MMA mass. The content of the body unit was 100% by mass (PMMA).

<Polycarbonate (C-1)>
The following polycarbonate was prepared.
"Calibre 301-40" manufactured by Sumika Polycarbonate Co., Ltd.
300 ° C. according to MVR (JIS K7210-1: 2014)
Load 1.2 kg, measured at 10 min conditions) = 40 cm ^3/10 min Mw = 35000
Mw / Mn = 2.0
Glass transition temperature 148 ° C

<Phenoxy resin (D-1)>
The following phenoxy resins were prepared.
"YP-50S" manufactured by Nippon Steel & Sumikin Chemical Co., Ltd.
Mw = 22000
Mw / Mn = 2.5
Glass transition temperature 96 ° C

<Manufacturing Example 3> (Manufacturing of thermoplastic resin (B-1))
50 parts by mass of polycarbonate (C-1) and 50 parts by mass of phenoxy resin (D-1) were dry-blended at 25 ° C. to obtain a thermoplastic resin (B-1). The evaluation results of the obtained thermoplastic resin (B-1) are shown in Table 1.

<Manufacturing Examples 4 to 8> (Manufacturing of thermoplastic resins (B-2) to (B-6))
In Production Example 3, the thermoplastic resin (B-2) was dry-blended in the same manner as in Production Example 3 except that the amounts of the polycarbonate (C-1) and the phenoxy resin (D-1) were changed as shown in Table 1. ~ (B-6) was obtained. Table 1 shows the evaluation results of the obtained thermoplastic resins (B-2) to (B-6).

<Polymer processing aid (PA-1)>
The following polymer processing aids were prepared.
"Metabrene (registered trademark) P550A" manufactured by Mitsubishi Chemical Corporation
Average degree of polymerization: 7734
Content of MMA monomer unit: 88% by mass
Content of butyl acrylate monomer unit: 12% by mass

<Example 1>
20 parts by mass of (meth) acrylic resin (A-1), 80 parts by mass of (meth) acrylic resin (A-2), 3.0 parts by mass of thermoplastic resin (B-1), and polymer processing aid (PA-1) 2.0 parts by mass was dry-blended at 25 ° C., and 250 by using a 20 mmφ twin-screw extruder (“KZW20TW-45MG-NH-600” manufactured by Technobel Co., Ltd., L / D = 45). The melt-kneaded product was melt-kneaded at ° C., and the melt-kneaded product was extruded at a discharge rate of 7 kg / h to produce a (meth) acrylic resin composition.
The obtained (meth) acrylic resin composition was dried at 80 ° C. for 12 hours. Using a 20 mmφ single-screw extruder (manufactured by Toyo Seiki Seisakusho Co., Ltd.), a full-flight screw with L / D = 21 and a compression ratio of 1.9, the cylinder temperature is 180 to 255 ° C, the die temperature is 250 ° C, and the discharge rate is 2 kg. The (meth) acrylic resin composition was extruded from a T-die at / h with a lip opening of 0.5 mm, and was taken up with a roll having a surface temperature of 100 ° C. at a take-up speed of 1.2 m / min, having a width of 110 mm and a thickness of 225 μm. A (meth) acrylic resin film was obtained.
The obtained raw film was cut out to a size of 80 mm × 80 mm. This film was biaxially stretched using a bitank batch biaxial stretching tester. Simultaneous biaxial stretching was carried out in the first tank under the conditions of a stretching temperature of 140 ° C., a stretching speed of 1300% / min, and a stretching ratio of 2.37 × 2.37, and then in the second tank, a heat fixing temperature of 115 ° C., 90. After heat-fixing under the condition of seconds, the film was rapidly cooled to obtain a biaxially stretched film having a thickness of 40 μm. Table 2 shows the evaluation results of the obtained biaxially stretched film.
Further, a biaxially stretched film was obtained by performing a stretching treatment under the same conditions as those described above except that the stretching temperature was changed to 145 ° C. With respect to the obtained biaxially stretched film, the phase difference in the thickness direction was measured according to the above-mentioned measuring method. The evaluation results are shown in Table 2.

<Examples 2 to 4, Comparative Examples 1 and 2>
In Example 1, a raw film and a biaxially stretched film were obtained in the same manner as in Example 1 except that the composition of the resin composition was changed as shown in Table 2. The evaluation results are shown in Table 2.

The films of Examples 1 to 4 all have high transparency, low phase difference, small ΔRth, and excellent molding stability. On the other hand, the film of Comparative Example 1 had a large ΔRth, and the film of Comparative Example 2 had a large phase difference.

Claims (7)

(Meta) acrylic resin (A1) with triplet display syndiotacticity of 45 to 58% and (meth) acrylic resin (A2) with triplet display syndiotacticity of 65% or more. (Meta) acrylic resin (A1) / (meth) acrylic resin (A2) at a mass ratio of 1/99 to 30/70 (meth) acrylic resin (A), and polycarbonate (C). And the phenoxy resin (D) are made of a thermoplastic resin (B) containing the polycarbonate (C) / phenoxy resin (D) in a mass ratio of 1/99 to 99/1.
A (meth) acrylic resin film comprising a (meth) acrylic resin composition in which the content of the thermoplastic resin (B) is 1 to 5 parts by mass with respect to 100 parts by mass of the (meth) acrylic resin (A). There,
A (meth) acrylic resin film having a thickness direction retardation of the (meth) acrylic resin film of −5 to 5 nm and a haze of 0.2% or less. The (1) according to claim 1, wherein the ratio of the tear strength in the longitudinal direction (MD) to the tear strength in the width direction (TD) measured according to JIS K7128-1: 1998 is 0.9 to 1.1. Meta) Acrylic resin film. Claim ¹ in which the photoelastic coefficient of the thermoplastic resin (B) is 67 × 10 ^{-12 to} 90 × 10 ^-12 Pa ^-1 , and the orientation birefringence is 80 × 10 ^{-4 to} 160 × 10 ^-4. Alternatively, the (meth) acrylic resin film according to 2. The (meth) acrylic resin film according to any one of claims 1 to 3, which is a non-stretched film. The (meth) acrylic resin film according to any one of claims 1 to 4, which is an optical film. The (meth) acrylic resin film according to any one of claims 1 to 4, which is a decorative film. A (meth) acrylic stretched film comprising the (meth) acrylic resin film according to any one of claims 1 to 3.