Film composed of polycarbonate resin composition, and surface protective film

Abstract

To provide a film which is excellent in transparency, heat resistance, and surface lubricity and suppresses coloration, and to provide a surface protective film comprising the film.SOLUTION: The film is composed of a polycarbonate resin composition, and the surface protective film comprises the film. The polycarbonate resin composition contains a polycarbonate resin and a crosslinked acrylic resin. The polycarbonate resin contains a structural unit (A) represented by the following formula (1) and a structural unit (B) derived from one or more dihydroxy compounds selected from the group consisting of a dihydroxy compound of an aliphatic hydrocarbon, a dihydroxy compound of an alicyclic hydrocarbon, and an ether-containing dihydroxy compound. The crosslinked acrylic resin has a 10% weight loss temperature in air of 325°C or higher.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a film made of a polycarbonate resin composition and a surface protection film.

Background Art

[0002] As display devices such as personal computers, smartphones, and tablet terminals, liquid crystal displays and organic EL displays are widely used. Conventionally, for optical films such as polarizing plates provided in displays, films based on resins such as triacetyl cellulose (hereinafter sometimes referred to as "TAC"), polyester, acrylic, cycloolefin polymer (hereinafter sometimes referred to as "COP"), etc. have been exclusively used. With the recent technological developments such as thinning, enlargement, and flexibility of displays, optical films are required to have characteristics such as dimensional stability at higher temperatures, thin film processability, and low optical distortion. There has been a situation where conventional films cannot satisfy the physical properties required for optical films.

[0003] In addition, due to concerns about the depletion of petroleum resources, the development of plastics made from carbon-neutral plant-derived monomers is required. Under such circumstances, in recent years, polycarbonate resins produced using isosorbide (hereinafter sometimes referred to as "ISB"), a plant-derived raw material, have been developed and applied to automotive parts and optical applications (see, for example, Patent Documents 1 and 2). Furthermore, films have been developed in which acrylic particles are added to polycarbonate resins to improve surface lubricity (see, for example, Patent Document 3).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Patent Document 3

SUMMARY OF THE INVENTION

PROBLEMS TO BE SOLVED BY THE INVENTION

[0005] When acrylic particles used for improving the surface slipperiness of a film are blended with a polycarbonate resin, there has been a concern that the film may be colored during extrusion film formation. In addition, there has been a possibility that the transparency of the film may be reduced by the addition of acrylic-based particles.

[0006] The present invention has been made in view of such a background, and aims to provide a film having excellent transparency, heat resistance, and surface slipperiness and suppressed coloring, and a surface protection film made of the film.

MEANS FOR SOLVING THE PROBLEMS

[0007] That is, the present invention has the following aspects. [1] A polycarbonate resin containing a structural unit (A) represented by the following formula (1) and a structural unit (B) derived from one or more dihydroxy compounds selected from the group consisting of dihydroxy compounds of aliphatic hydrocarbons, dihydroxy compounds of alicyclic hydrocarbons, and dihydroxy compounds containing an ether, and A film composed of a polycarbonate resin composition containing a crosslinked acrylic resin having a 10% weight loss temperature in air of 325 °C or higher.

[0008]

CHEM.

[0009] [2] The film according to [1], wherein the structural unit (B) is a structural unit derived from a dihydroxy compound of an alicyclic hydrocarbon. [3] The film according to [2], wherein the structural unit derived from the dihydroxy compound of the alicyclic hydrocarbon is a structural unit represented by the following formula (2).

[0010] [Chemical formula]

[0011] [4] The crosslinked acrylic resin is in particulate form, and the average particle diameter of the crosslinked acrylic resin is 0.5 μm or more and less than 2.0 μm. The film according to any one of [1] to [3]. [5] The content of the crosslinked acrylic resin is 0.05% by mass or more and less than 3.0% by mass with respect to 100% by mass of the polycarbonate resin composition. The film according to any one of [1] to [4]. [6] The glass transition temperature of the polycarbonate resin composition is 110°C or more and 150°C or less. The film according to any one of [1] to [5].

[0012] [7] A surface protection film comprising the film according to any one of [1] to [6]. [Advantages of the Invention]

[0013] According to the present invention, it is possible to provide a film excellent in transparency, heat resistance, surface smoothness, and suppressed coloring, and a surface protection film comprising the film. [Embodiments for Carrying Out the Invention]

[0014] Embodiments of the present invention will be described in detail below. However, the description of the configurations described below is an example (i.e., a representative example) of an embodiment of the present invention, and the present invention is not limited to the following content as long as it does not exceed the gist thereof. In this specification, the "repeating structural unit" means a structural unit in which the same structure repeatedly appears in a resin, and each of them is a structural unit that constitutes the resin by being connected. For example, in the case of a polycarbonate resin, it is called a repeating structural unit including a carbonyl group. Further, the "structural unit" means a partial structure constituting a resin, and specifically means a specific partial structure included in the repeating structural unit. For example, it refers to a partial structure sandwiched between adjacent linking groups in a resin, or a polymerization reactive group present at the terminal portion of a polymer and a partial structure sandwiched between the linking group adjacent to the polymerizable reactive group. More specifically, in the case of a polycarbonate resin, a carbonyl group is a linking group, and the partial structure sandwiched between adjacent carbonyl groups is called a structural unit. In this specification, when the expression "~" is used, it is used in the sense of including the numerical values or physical values described before and after it. Further, the numerical values or physical values described as upper and lower limits are used in the sense of including those values. Also, "parts by weight" and "parts by mass", and "weight%" and "mass%" are substantially synonymous, respectively.

[0015] The film is made of a polycarbonate resin composition containing a predetermined polycarbonate resin and a predetermined crosslinked acrylic resin.

[0016] <Polycarbonate resin> The polycarbonate resin contains a structural unit (A) represented by the following formula (1).

[0017]

Chemical formula

[0018] Examples of the dihydroxy compound (hereinafter sometimes referred to as "the first compound") that forms the structural unit (A) include isosorbide, isomannide, and isoidide, which are in a stereoisomeric relationship. These may be used alone or in combination of two or more. Among these, isosorbide is most preferred in terms of availability, ease of production, optical properties, and moldability. Isosorbide is obtained by dehydrative condensation of sorbitol, and sorbitol is abundantly present as a plant-derived resource and is produced from various starches that are easily available.

[0019] The content ratio of the structural unit (A) in the polycarbonate resin is preferably 10% by mass or more and 90% by mass or less, more preferably 20% by mass or more and 80% by mass or less, based on 100% by mass of all the structural units constituting the polycarbonate resin. Depending on the properties required for the film, the mass ratio of the structural unit (A) is more preferably 25% by mass or more and 70% by mass or less. When the content ratio of the structural unit (A) is too small, the glass transition temperature of the polycarbonate resin may become low, and the heat resistance of the film may be insufficient. Also, in this case, there may be a risk of cutting defects when cutting the strand-like resin into pellets in the latter stage of the polymerization process of the polycarbonate resin, and manufacturing problems are likely to occur. On the other hand, when the content ratio of the structural unit (A) is too large, it becomes difficult to advance the polymerization reaction to the desired degree of polymerization, and there is a risk of becoming a so-called hard and brittle resin. Also, in this case, the dimensional stability may be impaired due to an increase in the water absorption of the resin.

[0020] The polycarbonate resin contains a structural unit (B) derived from one or more dihydroxy compounds selected from the group consisting of aliphatic hydrocarbon dihydroxy compounds (i.e., aliphatic hydrocarbons having two hydroxy groups), alicyclic hydrocarbon dihydroxy compounds (i.e., alicyclic hydrocarbons having two hydroxy groups), and ether group-containing hydrocarbon dihydroxy compounds (i.e., ether group-containing hydrocarbons having two hydroxy groups).

[0021] Examples of the dihydroxy compounds of aliphatic hydrocarbons include linear aliphatic dihydroxy compounds such as ethylene glycol, 1,3-propanediol, 1,2-propanediol, 1,4-butanediol, 1,5-heptanediol, 1,6-hexanediol, 1,9-nonanediol, 1,10-decanediol, 1,12-dodecanediol, etc.; and branched-chain aliphatic dihydroxy compounds such as 1,3-butanediol, 1,2-butanediol, neopentyl glycol, hexylene glycol, etc.

[0022] Examples of the dihydroxy compounds of alicyclic hydrocarbons include primary alcohol dihydroxy compounds of alicyclic hydrocarbons exemplified by 1,2-cyclohexanedimethanol, 1,3-cyclohexanedimethanol, 1,4-cyclohexanedimethanol, tricyclodecane dimethanol, pentacyclopentadecane dimethanol, 2,6-decalin dimethanol, 1,5-decalin dimethanol, 2,3-decalin dimethanol, 2,3-norbornane dimethanol, 2,5-norbornane dimethanol, 1,3-adamantane dimethanol, dihydroxy compounds derived from terpene compounds such as limonene, etc.; and secondary or tertiary alcohol dihydroxy compounds of alicyclic hydrocarbons exemplified by 1,2-cyclohexanediol, 1,4-cyclohexanediol, 1,3-adamantane diol, hydrogenated bisphenol A, 2,2,4,4-tetramethyl-1,3-cyclobutanediol, etc.

[0023] Examples of the ether-containing dihydroxy compounds include oxyalkylene glycols. As the oxyalkylene glycols, for example, diethylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycol, polypropylene glycol, etc. can be used.

[0024] As the dihydroxy compound (hereinafter sometimes referred to as "the second compound") that forms the structural unit (B), it preferably includes a dihydroxy compound of an aliphatic hydrocarbon or a dihydroxy compound of an alicyclic hydrocarbon, and more preferably includes a dihydroxy compound of an alicyclic hydrocarbon. As the dihydroxy compound of an alicyclic hydrocarbon, it preferably includes tricyclodecane dimethanol. Further, as the structural unit (B), it preferably includes a structural unit represented by the following formula (2).

[0025] [Chemical formula]

[0026] The content ratio of the structural unit (B) in the polycarbonate resin is preferably 5% by mass or more, more preferably 10% by mass or more, and further preferably 20% by mass or more with respect to 100% by mass of all the structural units constituting the polycarbonate resin. Also, it is preferably 70% by mass or less, more preferably 60% by mass or less, and further preferably 55% by mass or less. In these cases, the optical properties of the film can be improved while maintaining excellent heat resistance.

[0027] Within a range not impairing the effects of the present invention, the polycarbonate resin may contain a structural unit derived from a dihydroxy compound other than the first compound and the second compound (hereinafter referred to as "the third compound") and a structural unit derived from a compound other than the dihydroxy compound. Examples of the third compound include a dihydroxy compound containing an acetal ring (that is, a cyclic acetal structure) and a dihydroxy compound containing an aromatic group such as a bisphenol compound. Further, the polycarbonate resin can contain a structural unit derived from a diester compound containing an aromatic group such as a bisphenol compound. A polycarbonate resin in which a structural unit derived from a diester compound is partially incorporated is called a polyester carbonate resin. That is, the polycarbonate resin in the present specification is a concept including a polyester carbonate resin.

[0028] Examples of the dihydroxy compound containing an acetal ring include spiroglycol (also known as 3,9-bis(1,1-dimethyl-2-hydroxyethyl)-2,4,8,10-tetraoxaspiro[5,5]undecane) and dioxane glycol (also known as 2-(1,1-dimethyl-2-hydroxyethyl)-5-ethyl-5-hydroxymethyl-1,3-dioxane).

[0029] By using a dihydroxy compound or a diester compound containing an aromatic group such as a bisphenol compound as a copolymer component, the heat resistance of the surface protective film may be improved. On the other hand, when the polycarbonate resin contains many structural units derived from a dihydroxy compound containing an aromatic group, the weather resistance tends to decrease. In addition, there is a large difference in polymerization reactivity between the dihydroxy compound or diester compound containing an aromatic group and the first compound and the second compound. Therefore, the dihydroxy compound or diester compound containing an aromatic group remains as a terminal group, making it difficult to obtain a high molecular weight polycarbonate resin and tending to reduce the impact resistance. When the reaction temperature is increased to accelerate the reaction, the structural unit (A) tends to thermally decompose and the polycarbonate resin tends to be colored. For these reasons, the content ratio of the structural unit derived from the dihydroxy compound or diester compound containing an aromatic group in the polycarbonate resin is preferably 10% by mass or less, and more preferably 5% by mass or less.

[0030] Examples of the dihydroxy compound containing an aromatic group include aromatic bisphenol compounds such as 2,2-bis(4-hydroxyphenyl)propane, 2,2-bis(3-methyl-4-hydroxyphenyl)propane, 2,2-bis(4-hydroxy-3,5-dimethylphenyl)propane, 2,2-bis(4-hydroxy-3,5-diethylphenyl)propane, 2,2-bis(4-hydroxy-(3-phenyl)phenyl)propane, 2,2-bis(4-hydroxy-(3,5-diphenyl)phenyl)propane, 2,2-bis(4-hydroxy-3,5-dibromophenyl)propane, bis(4-hydroxyphenyl)methane, 1,1-bis(4-hydroxyphenyl)ethane, 2,2-bis(4-hydroxyphenyl)butane, 2,2-bis(4-hydroxyphenyl)pentane, 1,1-bis(4-hydroxyphenyl)-1-phenylethane, bis(4-hydroxyphenyl)diphenylmethane, 1,1-bis(4-hydroxyphenyl)-2-ethylhexane, 1,1-bis(4-hydroxyphenyl)decane, bis(4-hydroxy-3-nitrophenyl)methane, 3,3-bis(4-hydroxyphenyl)pentane, 1,3-bis(2-(4-hydroxyphenyl)-2-propyl)benzene, 1,3-bis(2-(4-hydroxyphenyl)-2-propyl)benzene, 2,2-bis(4-hydroxyphenyl)hexafluoropropane, 1,1-bis(4-hydroxyphenyl)cyclohexane, bis(4-hydroxyphenyl)sulfone, 2,4'-dihydroxydiphenylsulfone, bis(4-hydroxyphenyl)sulfide, bis(4-hydroxy-3-methylphenyl)sulfide, bis(4-hydroxyphenyl)disulfide, 4,4'-dihydroxydiphenyl ether, 4,4'-dihydroxy-3,3'-dichlorodiphenyl ether; dihydroxy compounds having an ether group bonded to an aromatic group such as 2,2-bis(4-(2-hydroxyethoxy)phenyl)propane, 2,2-bis(4-(2-hydroxypropoxy)phenyl)propane, 1,3-bis(2-hydroxyethoxy)benzene, 4,4'-bis(2-hydroxyethoxy)biphenyl, bis(4-(2-hydroxyethoxy)phenyl)sulfone;Dihydroxy compounds having a fluorene ring such as 9,9-bis(4-(2-hydroxyethoxy)phenyl)fluorene, 9,9-bis(4-hydroxyphenyl)fluorene, 9,9-bis(4-hydroxy-3-methylphenyl)fluorene, 9,9-bis(4-(2-hydroxypropoxy)phenyl)fluorene, 9,9-bis(4-(2-hydroxyethoxy)-3-methylphenyl)fluorene, 9,9-bis(4-(2-hydroxypropoxy)-3-methylphenyl)fluorene, 9,9-bis(4-(2-hydroxyethoxy)-3-isopropylphenyl)fluorene, 9,9-bis(4-(2-hydroxyethoxy)-3-isobutylphenyl)fluorene, 9,9-bis(4-(2-hydroxyethoxy)-3-tert-butylphenyl)fluorene, 9,9-bis(4-(2-hydroxyethoxy)-3-cyclohexylphenyl)fluorene, 9,9-bis(4-(2-hydroxyethoxy)-3-phenylphenyl)fluorene, 9,9-bis(4-(2-hydroxyethoxy)-3,5-dimethylphenyl)fluorene, 9,9-bis(4-(2-hydroxyethoxy)-3-tert-butyl-6-methylphenyl)fluorene, 9,9-bis(4-(3-hydroxy-2,2-dimethylpropoxy)phenyl)fluorene, etc.;

[0031] Examples of the diester compound include, for example, the dicarboxylic acids shown below. Specifically, aromatic dicarboxylic acids such as terephthalic acid, phthalic acid, isophthalic acid, 4,4'-diphenyldicarboxylic acid, 4,4'-diphenyletherdicarboxylic acid, 4,4'-benzophenonedicarboxylic acid, 4,4'-diphenoxyethanedicarboxylic acid, 4,4'-diphenylsulfonedicarboxylic acid, 2,6-naphthalenedicarboxylic acid; alicyclic dicarboxylic acids such as 1,2-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid; aliphatic dicarboxylic acids such as malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid. These dicarboxylic acid components can be used as raw materials for polyester carbonate resins as the dicarboxylic acids themselves, but depending on the production method of the polyester carbonate resin, dicarboxylic acid esters such as methyl ester forms and phenyl ester forms, and dicarboxylic acid derivatives such as dicarboxylic acid halides can also be used as raw materials as appropriate.

[0032] The dihydroxy compound used as a raw material for the polycarbonate resin may contain various stabilizers such as reducing agents, antioxidants, deoxidizers, light stabilizers, antacids, pH stabilizers, and heat stabilizers. In particular, since the first compound has a property of being easily deteriorated in an acidic state, the deterioration of the first compound can be suppressed by using a basic stabilizer in the production process of the polycarbonate resin. Thereby, the quality of the obtained polycarbonate resin can be further improved.

[0033] Examples of the carbonic acid diester used as a raw material for the polycarbonate resin usually include compounds represented by the following formula (3). These carbonic acid diesters may be used alone or in combination of two or more.

[0034]

Chemical formula

[0035] In the above formula (3), A 1and A 2 is each independently a substituted or unsubstituted aliphatic hydrocarbon group having 1 to 18 carbon atoms or a substituted or unsubstituted aromatic hydrocarbon group. A 1 and A 2 may be the same as or different from A 1 and A 2 is preferably a substituted or unsubstituted aromatic hydrocarbon group, more preferably an unsubstituted aromatic hydrocarbon group. Examples of the carbonic acid diester represented by the formula (3) include substituted diphenyl carbonates such as diphenyl carbonate and ditolyl carbonate; dimethyl carbonate, diethyl carbonate, di-t-butyl carbonate and the like. The carbonic acid diester represented by the formula (3) is preferably diphenyl carbonate or substituted diphenyl carbonate, more preferably diphenyl carbonate.

[0036] The carbonic acid diester may contain impurities such as chloride ions, and the impurities may inhibit the polycondensation reaction or deteriorate the color tone of the resulting polycarbonate resin. Therefore, it is preferable to use a carbonic acid diester purified by distillation or the like as necessary.

[0037] <Method for producing polycarbonate resin> The polycarbonate resin is synthesized, for example, by polycondensing the aforementioned dihydroxy compound and carbonic acid diester by a transesterification reaction. More specifically, the polycarbonate resin can be obtained by removing, outside the system, monohydroxy compounds and the like by-produced in the transesterification reaction together with the polycondensation.

[0038] The transesterification reaction proceeds in the presence of a transesterification catalyst (hereinafter, the transesterification catalyst is referred to as a "polymerization catalyst"). The type of the polymerization catalyst can have a very great influence on the reaction rate of the transesterification reaction and the quality of the resulting polycarbonate resin.

[0039] The polymerization catalyst is not particularly limited as long as it can satisfy the transparency, color tone, heat resistance, weather resistance, and mechanical strength of the desired polycarbonate resin. Examples of the polymerization catalyst include metal compounds of Group I or Group II in the long-period periodic table (hereinafter referred to as "Group 1" and "Group 2", respectively), and basic compounds such as basic boron compounds, basic phosphorus compounds, basic ammonium compounds, and amine compounds. Among them, Group 1 metal compounds and / or Group 2 metal compounds are preferred.

[0040] Examples of the Group 1 metal compounds include sodium hydroxide, potassium hydroxide, lithium hydroxide, cesium hydroxide, sodium hydrogen carbonate, potassium hydrogen carbonate, lithium hydrogen carbonate, cesium hydrogen carbonate, sodium carbonate, potassium carbonate, lithium carbonate, cesium carbonate, sodium acetate, potassium acetate, lithium acetate, cesium acetate, sodium stearate, potassium stearate, lithium stearate, cesium stearate, sodium borohydride, potassium borohydride, lithium borohydride, cesium borohydride, sodium phenylborate, potassium phenylborate, lithium phenylborate, cesium phenylborate, sodium benzoate, potassium benzoate, lithium benzoate, cesium benzoate, disodium hydrogen phosphate, dipotassium hydrogen phosphate, dilithium hydrogen phosphate, disodium hydrogen phosphate, dipotassium phenylphosphate, dilithium phenylphosphate, and disodium phenylphosphate. Examples of the Group 1 metal compounds also include alcoholates or phenolates of sodium, potassium, lithium, or cesium; and the disodium salt, dipotassium salt, dilithium salt, or dicesium salt of bisphenol A. From the viewpoints of polymerization activity and the color tone of the obtained polycarbonate resin, lithium compounds are preferred as the Group 1 metal compounds.

[0041] Examples of Group 2 metal compounds include calcium hydroxide, barium hydroxide, magnesium hydroxide, strontium hydroxide, calcium hydrogen carbonate, barium hydrogen carbonate, magnesium hydrogen carbonate, strontium hydrogen carbonate, calcium carbonate, barium carbonate, magnesium carbonate, strontium carbonate, calcium acetate, barium acetate, magnesium acetate, strontium acetate, calcium stearate, barium stearate, magnesium stearate, and strontium stearate. From the viewpoints of polymerization activity and the color tone of the resulting polycarbonate resin, as the Group 2 metal compound, magnesium compounds, calcium compounds, and barium compounds are preferred, magnesium compounds and / or calcium compounds are more preferred, and calcium compounds are most preferred.

[0042] In addition, it is also possible to use basic compounds such as basic boron compounds, basic phosphorus compounds, basic ammonium compounds, and amine compounds in combination with the above-mentioned Group 1 metal compound and / or Group 2 metal compound as an auxiliary, but it is more preferable to use only the Group 1 metal compound and / or Group 2 metal compound. From the viewpoint of the color tone of the resulting polycarbonate resin, it is most preferred to use only the Group 2 metal compound.

[0043] Examples of basic boron compounds include metal salts such as tetramethyl boron, tetraethyl boron, tetrapropyl boron, tetrabutyl boron, trimethylethyl boron, trimethylbenzyl boron, trimethylphenyl boron, triethylmethyl boron, triethylbenzyl boron, triethylphenyl boron, tributylbenzyl boron, tributylphenyl boron, tetraphenyl boron, benzyltriphenyl boron, methyltriphenyl boron, and butyltriphenyl boron. Examples of the metal salts include sodium salts, potassium salts, lithium salts, calcium salts, barium salts, magnesium salts, and strontium salts.

[0044] Examples of the basic phosphorus compound include triethylphosphine, tri-n-propylphosphine, triisopropylphosphine, tri-n-butylphosphine, triphenylphosphine, tributylphosphine, and quaternary phosphonium salts.

[0045] Examples of the basic ammonium compound include tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, trimethylethylammonium hydroxide, trimethylbenzylammonium hydroxide, trimethylphenylammonium hydroxide, triethylmethylammonium hydroxide, triethylbenzylammonium hydroxide, triethylphenylammonium hydroxide, tributylbenzylammonium hydroxide, tributylphenylammonium hydroxide, tetraphenylammonium hydroxide, benzyltriphenylammonium hydroxide, methyltriphenylammonium hydroxide, and butyltriphenylammonium hydroxide.

[0046] Examples of the amine compound include 4-aminopyridine, 2-aminopyridine, N,N-dimethyl-4-aminopyridine, 4-diethylaminopyridine, 2-hydroxypyridine, 2-methoxypyridine, 4-methoxypyridine, 2-dimethylaminoimidazole, 2-methoxyimidazole, imidazole, 2-mercaptoimidazole, 2-methylimidazole, aminoquinoline, and guanidine.

[0047] The amount of the polymerization catalyst used is preferably 0.1 μmol or more, more preferably 0.3 μmol or more, and still more preferably 0.5 μmol or more per 1 mol of the total dihydroxy compound used in the reaction. Also, the amount of the polymerization catalyst used is preferably 300 μmol or less, more preferably 100 μmol or less, and still more preferably 50 μmol or less per 1 mol of the total dihydroxy compound used in the reaction.

[0048] By adjusting the amount of the polymerization catalyst used within the aforementioned range, the polymerization rate can be increased, so that it becomes possible to obtain a polycarbonate resin having a desired molecular weight without necessarily increasing the polymerization temperature. Therefore, it is possible to suppress the deterioration of the color tone of the polycarbonate resin. Further, since it is possible to prevent unreacted raw materials from volatilizing during the polymerization and the molar ratio of the dihydroxy compound and the carbonic acid diester from being disrupted, it is possible to more surely obtain a resin having a desired molecular weight and copolymerization ratio. Furthermore, since the concurrent occurrence of side reactions can be suppressed, it is possible to further prevent the deterioration of the color tone of the polycarbonate resin or the coloring during the molding process.

[0049] Considering the adverse effects of sodium, potassium, cesium, and iron on the color tone of the polycarbonate resin, the total content of sodium, potassium, cesium, and iron in the polycarbonate resin is preferably 1 weight ppm or less. In this case, it is possible to further prevent the deterioration of the color tone of the polycarbonate resin and make the color tone of the polycarbonate resin better. From the same viewpoint, the total content of sodium, potassium, cesium, and iron in the polycarbonate resin is more preferably 0.5 weight ppm or less. Incidentally, these metals may be mixed not only from the catalyst used but also from the raw materials and the reaction apparatus. Regardless of the source, it is preferable that the total amount of these metals and compounds containing these metals in the polycarbonate resin be within the aforementioned range as the total content of sodium, potassium, cesium, and iron.

[0050] The dihydroxy compound and the diester carbonate are preferably melted separately or mixed uniformly before the transesterification reaction. The melting or mixing temperature is usually 80°C or higher, preferably 90°C or higher, and usually 200°C or lower, preferably 150°C or lower, more preferably 120°C or lower. In this case, the dissolution rate can be increased, the solubility can be sufficiently improved, and problems such as solidification can be sufficiently avoided. Furthermore, in this case, the thermal degradation of the dihydroxy compound can be sufficiently suppressed, and the quality represented by the color tone of the obtained polycarbonate resin can be made even better.

[0051] The melting or mixing of the dihydroxy compound and the diester carbonate is carried out in an oxygen concentration atmosphere within a predetermined range. This oxygen concentration is preferably 10 vol% or less. More preferably, it is 0.0001 vol% or more and 10 vol% or less, still more preferably 0.0001 vol% or more and 5 vol% or less, and even more preferably 0.0001 vol% or more and 1 vol% or less. In this case, the color tone can be made better and the reactivity can be increased.

[0052] The method of polycondensing the dihydroxy compound and the diester carbonate is carried out in multiple stages using a plurality of reactors in the presence of the aforementioned catalyst. The reaction mode includes a batch method, a continuous method, or a combination of a batch method and a continuous method. From the viewpoint of obtaining a polycarbonate resin with a smaller heat history and excellent productivity, it is preferable to adopt the continuous method.

[0053] From the viewpoints of controlling the polymerization rate and the quality of the polycarbonate resin, it is preferable to appropriately select the jacket temperature, the internal temperature, and the pressure in the reaction system according to the reaction stage. Specifically, in the initial stage of the polycondensation reaction, it is preferable to obtain a prepolymer at a relatively low temperature and low vacuum, and in the later stage of the reaction, it is preferable to increase the molecular weight to a predetermined value at a relatively high temperature and high vacuum. In this case, the distillation of unreacted monomers is suppressed, and it becomes easier to adjust the molar ratio of the dihydroxy compound and the carbonic acid diester to a desired ratio. As a result, a decrease in the polymerization rate can be suppressed. Further, it becomes possible to more surely obtain a polymer having a desired molecular weight and end groups.

[0054] The polymerization catalyst can be added to the raw material preparation tank or the raw material storage tank, or can be directly added to the polymerization reactor. From the viewpoints of supply stability and control of the polycondensation reaction, it is preferable to install a catalyst supply line in the middle of the raw material line before being supplied to the polymerization reactor and supply the polymerization catalyst in an aqueous solution.

[0055] By adjusting the temperature of the polycondensation reaction, it becomes possible to improve productivity and avoid an increase in the thermal history of the product. Further, it becomes possible to further prevent the volatilization of monomers, the decomposition and coloring of the polycarbonate resin. Specifically, as the reaction conditions in the first stage of the reaction, the following conditions can be adopted. That is, the maximum temperature of the internal temperature of the polymerization reactor is usually set in the range of 160 to 230 ° C, preferably 170 to 220 ° C, more preferably 180 to 210 ° C. Further, the pressure of the polymerization reactor (hereinafter, the pressure represents the absolute pressure) is usually set in the range of 1 to 110 kPa, preferably 5 to 50 kPa, more preferably 7 to 30 kPa. Further, the reaction time is usually set in the range of 0.1 to 10 hours, preferably 1 to 5 hours. The first stage of the reaction is preferably carried out while distilling off the generated monohydroxy compound out of the reaction system.

[0056] From the second stage onwards, it is preferable to gradually lower the pressure of the reaction system from the pressure of the first stage, and while continuously removing the monohydroxy compound generated from the reaction system, finally set the pressure (absolute pressure) of the reaction system to 1 kPa or less. Further, the maximum temperature of the internal temperature of the polymerization reactor is usually set in the range of 200 to 260 °C, preferably 210 to 240 °C, more preferably 215 to 230 °C. Also, the reaction time is usually set in the range of 0.1 to 10 hours, preferably 0.5 to 5 hours, more preferably 1 to 3 hours.

[0057] After polymerization as described above, the polycarbonate resin can usually be cooled and solidified and pelletized with a rotary cutter or the like. The method of pelletization is not limited, but methods such as extracting the polycarbonate resin from the final-stage polymerization reactor in a molten state, cooling and solidifying it in the form of strands and pelletizing it, supplying the molten polycarbonate resin from the final-stage polymerization reactor to a single-screw or twin-screw extruder, extruding it, and then cooling and solidifying it to pelletize it, or extracting the polycarbonate resin from the final-stage polymerization reactor in a molten state, cooling and solidifying it in the form of strands to pelletize it once, and then supplying the polycarbonate resin to a single-screw or twin-screw extruder again, melt-extruding it, and then cooling and solidifying it to pelletize it can be mentioned.

[0058] <Polycarbonate Resin Composition> The polycarbonate resin composition contains a polycarbonate resin and a crosslinked acrylic resin.

[0059] · Crosslinked Acrylic Resin In order to impart an uneven shape to the surface of the film and exhibit surface lubricity, the polycarbonate resin composition contains a crosslinked acrylic resin. From the viewpoint of improving surface lubricity, the crosslinked acrylic resin is preferably in the form of particles. From the viewpoint that the desired effect of improving surface lubricity can be maintained by the crosslinked acrylic resin maintaining its particle shape in the heating process when compounded with other resins such as polycarbonate resin or when forming a film, the 5% weight loss temperature of the crosslinked acrylic resin in air is preferably 300°C or higher, more preferably 320°C or higher, still more preferably 330°C or higher, even more preferably 340°C or higher, and particularly preferably 350°C or higher. Also, from the same viewpoint, the 10% weight loss temperature of the crosslinked acrylic resin in air is 325°C or higher, preferably 330°C or higher, more preferably 340°C or higher, still more preferably 350°C or higher, even more preferably 360°C or higher, and particularly preferably 365°C or higher. On the other hand, since there is substantially an upper limit even if the crosslinking density is increased in an attempt to excessively increase the heat resistance, the 5% weight loss temperature of the acrylic resin in air is usually 400°C or lower, preferably 390°C or lower, and the 10% weight loss temperature is usually 450°C or lower, preferably 440°C or lower.

[0060] From the viewpoint of easily lowering haze, the crosslinked acrylic resin preferably contains a crosslinked poly(meth)acrylate polymer. Here, (meth)acrylic acid means acrylic acid and / or methacrylic acid.

[0061] The crosslinked acrylic resin may be a homopolymer or a copolymer. In the case of a copolymer, examples include polymers containing two or more (meth)acrylate units, and copolymers of (meth)acrylate and polymerizable monomers other than (meth)acrylate can also be used. Examples of polymerizable monomers other than (meth)acrylate include styrene, α-methylstyrene, maleic anhydride, (meth)acrylonitrile, vinyl acetate, vinyl chloride, vinyl pyrrolidone, vinyl pyridine, and the like.

[0062] Specific examples of the crosslinked acrylic resin include crosslinked poly(methyl methacrylate), crosslinked poly(ethyl methacrylate), crosslinked poly(propyl methacrylate), crosslinked poly(butyl methacrylate), and the like. Among these, from the viewpoints of high particle hardness, excellent antiblocking property, and easy adjustment of the refractive index, crosslinked poly(methyl methacrylate) and crosslinked poly(ethyl methacrylate) are preferred, and crosslinked poly(methyl methacrylate) is more preferred.

[0063] When the average particle diameter of the crosslinked acrylic resin is excessively small, the resin composition becomes significantly thickened and film formation becomes difficult, and there is a risk that the lubricity imparted to the film surface by the crosslinked acrylic resin becomes insufficient. From such a viewpoint, the average particle diameter of the crosslinked acrylic resin is preferably 0.5 μm or more. Further, when the average particle diameter of the crosslinked acrylic resin is excessively large, the film is likely to tear when it is a thin film, or the unevenness of the film becomes large and the appearance becomes an unfavorable form. Further, in this case, when a filter is used in the extrusion process during film formation, there is a risk of filter clogging due to particles. From such a viewpoint, the average particle diameter of the crosslinked acrylic resin is preferably less than 2.0 μm, more preferably 1.0 μm or less. In addition, as the average particle diameter, when it is described in a catalog or the like, that value is adopted, and when there is no description, for example, it can be measured using a laser particle measuring instrument MICROTRAC MT-3000 manufactured by Nikkiso Co., Ltd. Note that the "average particle diameter" means the particle diameter at 50% of the integrated value in the particle size distribution obtained by the laser diffraction / scattering method.

[0064] The content of the crosslinked acrylic resin with respect to 100% by mass of the polycarbonate resin composition is preferably 0.05% by mass or more and less than 3.0% by mass. In this case, the effect of maintaining transparency and imparting lubricity is improved. From the same viewpoint, the content of the crosslinked acrylic resin with respect to 100% by mass of the polycarbonate resin composition is more preferably 0.05% by mass or more and 2.0% by mass or less, and even more preferably 0.1% by mass or more and 1.0% by mass or less.

[0065] In addition, various additives can be added to the polycarbonate resin composition as long as the effects of the present invention are not impaired. As the additives, additives commonly used in polycarbonate resins are used. Specifically, catalyst deactivators, dyes and pigments, ultraviolet absorbers, light stabilizers, flame retardants, flame retardant aids, inorganic fillers, impact modifiers, hydrolysis inhibitors, foaming agents, nucleating agents, antioxidants, heat stabilizers, neutralizing agents, lubricants, anti-fogging agents, anti-blocking agents, slip agents, dispersants, colorants, antistatic agents, conductivity imparting agents, crosslinking agents, crosslinking aids, metal deactivators, molecular weight regulators, antibacterial agents, antifungal agents, fluorescent brighteners, light diffusing agents (specifically, organic light diffusing agents, inorganic light diffusing agents, etc.) can be used.

[0066] The polycarbonate resin may contain a catalyst deactivator as described above as an additive. The catalyst deactivator is not particularly limited as long as it is an acidic substance and has a deactivating function for the polymerization catalyst. From the viewpoint of excellent effects of catalyst deactivation and coloring suppression, a phosphorus-based acidic compound is preferable as the catalyst deactivator, phosphonic acid (phosphorous acid) and phosphonic acid ester are more preferable, and phosphonic acid (phosphorous acid) is even more preferable.

[0067] By adjusting the addition amount of the phosphorus-based acidic compound according to the amount of the polymerization catalyst, the effects of catalyst deactivation and coloring suppression can be more reliably obtained, and the optical properties of the film can be further improved. The addition amount of the phosphorus-based acidic compound is preferably 0.5 times mol or more, more preferably 0.7 times mol or more, and even more preferably 0.8 times or more with respect to 1 mol of the metal atom of the polymerization catalyst. Further, it is preferably 5 times mol or less, more preferably 3 times mol or less, and even more preferably 1.5 times mol or less. The addition amount of the phosphorus-based acidic compound described above is the converted amount based on the amount of phosphorus atoms in the phosphorus-based acidic compound.

[0068] In addition, within a range that does not impair the effects of the present disclosure, the polycarbonate resin composition can contain one or more selected from, for example, synthetic resins such as aromatic polyesters, aliphatic polyesters, polyamides, polystyrenes, polyolefins, amorphous polyolefins, acrylonitrile-butadiene-styrene copolymers (ABS resins), acrylonitrile-styrene copolymers (AS resins); elastomers such as acrylic rubbers and butadiene rubbers; biodegradable resins such as polylactic acid and polybutylene succinate. These are added by kneading with polycarbonate resins, acrylic resins, etc. That is, the polycarbonate resin composition may be a polymer alloy.

[0069] <Method for producing resin composition> The polycarbonate resin composition can be obtained by mixing an additive containing a crosslinked acrylic resin, etc. with the polycarbonate resin as described above. More specifically, for example, the polycarbonate resin obtained by a polycondensation reaction in a polymerization reaction tank is introduced into an extruder, and additives, etc. are kneaded while being continuously supplied to the polycarbonate resin. Then, by-produced gases and low molecular weight volatile components are devolatilized and removed through a decompression facility, and the melt-kneaded product is extruded in a strand shape from the tip of the extruder and cut into pellets while being cooled and solidified. In this way, a pellet-shaped polycarbonate resin composition is obtained. As the extruder, a twin-screw extruder equipped with a decompression device at the vent port is preferable in order to obtain sufficient devolatilization ability and uniform dispersion of additives.

[0070] In order to improve the devolatilization efficiency in the extruder, by dropping a volatile liquid such as water into the system, the devolatilization of the volatile components in the molten resin can also be promoted. The number and position of the vent ports can be appropriately selected from the viewpoints of the length of the extruder and the devolatilization efficiency. Preferably, about 2 to 4 vent ports are provided.

[0071] In order to be suitably used for a film, it is preferable that the polycarbonate resin composition contains few foreign matters. Therefore, in order to remove foreign matters such as charred parts and gels in the polycarbonate resin obtained by melt polycondensation as described above, it is preferable to perform filtration using a filter. More specifically, after melt-extruding the polycarbonate resin composition with the above-mentioned vented twin-screw extruder to remove residual monomers, by-produced phenols, etc. by devolatilization under reduced pressure and mixing additives such as heat stabilizers, it is preferable to filter with a filter.

[0072] As the form of the filter, known ones such as a candle type, a pleated type, and a leaf disk type can be used. From the viewpoint of obtaining a filtration accuracy of 99%, the aperture of the filter is preferably 50 μm or less, more preferably 40 μm or less, and still more preferably 20 μm or less. When it is particularly desired to reduce foreign matters, the aperture of the filter is particularly preferably 10 μm or less. However, when the aperture becomes small, the pressure loss across the filter increases, which may cause damage to the filter or deterioration of the polycarbonate resin composition due to shear heating. Therefore, even when the filtration accuracy is 99%, the aperture of the filter is preferably 1 μm or more. The aperture of the filter is determined in accordance with ISO 16889:1999.

[0073] The polycarbonate resin composition filtered by the filter is discharged in the form of strands from a die head, cooled and solidified, and pelletized with a rotary cutter or the like. From the viewpoint of preventing contamination by foreign matters from the outside air, strand formation and pelletization are preferably carried out in a clean room with a higher cleanliness than class 7, more preferably class 6. The class of the clean room mentioned above is defined in JIS B 9920-1:2019.

[0074] When pelletizing, it is preferable to use a cooling method such as air cooling or water cooling. When performing air cooling, from the viewpoint of preventing reattachment of foreign substances in the air, it is preferable to use air from which foreign substances in the air have been previously removed with a HEPA filter or the like as the air used for air cooling. When performing water cooling, as the water used for water cooling, it is preferable to use water from which metal components in the water have been removed with an ion exchange resin or the like and further foreign substances in the water have been removed with a water filter. In order to obtain a filtration accuracy of 99% removal, the mesh size of the water filter is preferably 0.45 to 10 μm.

[0075] From the viewpoint of increasing the effect of improving surface lubricity, it is preferable to disperse particulate crosslinked acrylic resin in at least the vicinity of the surface of the film. Specific methods thereof include a method (Method 1) in which the crosslinked acrylic resin is mixed and dispersed in the base material when forming the film in a single layer, a method (Method 2) in which the crosslinked acrylic resin is mixed and dispersed in the base material for forming the surface layer when forming a multi-layer film, and a method (Method 3) in which the crosslinked acrylic resin is mixed and dispersed in the base material for forming the surface layer when forming the surface layer by coating, foil transfer, or the like after forming the film.

[0076] In Method 1, during the production of the above resin composition, the crosslinked acrylic resin may be supplied to an extruder and kneaded with the polycarbonate resin composition in the same manner as other additives, or after producing the resin composition, the resin composition and the crosslinked acrylic resin may be kneaded using an extruder. Further, in the film forming step, the crosslinked acrylic resin may be added alone or as a masterbatch containing the crosslinked acrylic resin.

[0077] In Method 2, it may be added to the surface layer in the production process of the resin composition, the kneading process of the resin composition and the crosslinked acrylic resin using an extruder, and the film forming process in the same manner as Method 1. Method 2 is more preferable from the viewpoints of maintaining transparency and thin film processability because the amount of crosslinked acrylic resin in the entire film can be reduced compared to Method 1. In Method 3, a method generally used for the surface treatment of a film, specifically, the application of a polycarbonate resin composition is used. More specifically, after dispersing a crosslinked acrylic resin in a coating agent for forming a hard coat layer or a coating agent for imparting effects such as antireflection, antifogging property, and fingerprint adhesion prevention, this is applied. The application is preferably performed so as not to impair effects such as transparency and surface slipperiness.

[0078] <Method for manufacturing a film> As a method for forming a film using a polycarbonate resin composition, a casting method in which the polycarbonate resin composition is dissolved in a solvent and cast and then the solvent is removed, or a melt forming method in which the polycarbonate resin composition is melted without using a solvent can be adopted. Specific examples of the melt forming method include a melt extrusion method using a T-die, a calender molding method, a hot press method, a coextrusion method, a co-melting method, a multilayer extrusion, and an inflation molding method. The film forming method is not particularly limited, but preferably a melt forming method, and more preferably a melt extrusion method using a T-die.

[0079] When forming a film by the melt forming method, the forming temperature is preferably 280°C or lower, more preferably 270°C or lower, and even more preferably 265°C or lower. If the forming temperature is too high, foreign matters and bubbles may be generated in the film, defects in the film may increase, or the film may be colored. On the other hand, if the forming temperature is too low, the melt viscosity of the polycarbonate resin composition becomes too high, making it difficult to form a film and potentially making it difficult to produce a film with uniform thickness. From the perspective of avoiding this, the lower limit of the forming temperature is usually 200°C or higher, preferably 210°C or higher, and more preferably 220°C or higher. Here, the forming temperature of the film is the temperature during forming in the melt forming method, and usually, it is the value measured for the temperature of the polycarbonate resin at the die outlet where the molten polycarbonate resin is extruded.

[0080] In addition, if foreign matter is present in the film, when used as an optical film such as a surface protection film, it will be recognized as a defect such as light leakage, and the visibility may decrease. In order to remove foreign matter in the polycarbonate resin, it is preferable to attach a polymer filter after the extruder, filter the polycarbonate resin, and then extrude it from the die to form a film. At this time, it is necessary to connect the extruder, polymer filter, and die with pipes to transfer the molten polycarbonate resin. However, in order to suppress thermal degradation in the pipes as much as possible, it is preferable to arrange each facility so that the residence time is minimized. In addition, the processes of transporting and winding the film after extrusion are carried out in a clean room, and great care is required to prevent foreign matter from adhering to the film.

[0081] <Physical Properties of Polycarbonate Resin Composition> (Glass Transition Temperature) The glass transition temperature of the polycarbonate resin composition is preferably 110°C or higher and 150°C or lower, more preferably 127°C or higher and 145°C or lower. In this case, the film exhibits sufficient heat resistance. The glass transition temperature of the polycarbonate resin composition is controlled, for example, by the monomer composition (that is, the composition of structural units) constituting the polycarbonate resin, the type and addition amount of the crosslinked acrylic resin. For example, as the content ratio of structural unit A in the polycarbonate resin increases, the glass transition temperature tends to increase. Also, as the addition amount of the crosslinked acrylic resin increases, the glass transition temperature tends to decrease.

[0082] (Yellow Index (i.e., YI value)) The initial YI value of the polycarbonate resin composition is preferably 10 or less, more preferably 9.8 or less, and even more preferably 9.4 or less. In this case, the transparency of the film can be improved, and high visibility can be exhibited. The initial YI value means the YI value at the time of manufacturing the polycarbonate resin composition, and is the YI value of the polycarbonate resin composition in a state where the following heat retention (100 ° C, 200 hours) is not performed. Further, the difference ΔYI between the YI value of the resin composition after being held at 100 ° C for 200 hours and the initial YI value is preferably less than 7.0, and more preferably less than 6.5. The YI value of the resin composition is, for example, the measured value of the pellet-shaped resin composition.

[0083] <Physical properties of the film> The thickness of the film is preferably 10 μm or more. When the thickness is less than 10 μm, the film is likely to be wrinkled in the film manufacturing process, or the strength may be insufficient. Also, from the viewpoint of strength, the thickness is preferably 20 μm or more, and more preferably 40 μm or more. Further, from the viewpoint of the ease of occurrence of flatness defects due to winding marks when stored in a rolled state, the thickness of the film is preferably 300 μm or less, more preferably 250 μm or less, and even more preferably 200 μm or less.

[0084] The length of the film in the longitudinal direction is preferably 500 m or more, more preferably 1000 m or more, and even more preferably 1500 m or more. From the viewpoints of productivity and quality, it is preferable that the film is manufactured continuously. In the present specification, "long-sized" means that the dimension in the longitudinal direction is sufficiently larger than the dimension in the width direction of the film, and substantially means that it can be wound in the longitudinal direction into a coil shape. More specifically, it means that the dimension in the longitudinal direction of the film is 10 times or more larger than the dimension in the width direction. Further, the film obtained within a range not impairing the object of the present invention may be stretched. As the stretching method, a known method is used. For example, uniaxial stretching in the longitudinal direction, uniaxial stretching in the transverse direction using a tenter or the like, and uniaxial stretching with a fixed end are used. Further, simultaneous biaxial stretching, sequential biaxial stretching, etc. in which these stretchings are combined are used. The stretching may be performed batchwise, but continuous stretching is preferable in terms of productivity.

[0085] The total light transmittance of the film is preferably 90% or more, more preferably 91% or more, and even more preferably 91.5% or more. In these cases, it is possible to lower the light source of the liquid crystal display and the light emission amount of the organic EL display, reduce power consumption, suppress heat generation of the display device, and improve durability. Therefore, the film becomes suitable as a surface protection film for the display. The upper limit of the total light transmittance of the film is not particularly limited, but is usually 99% or less.

[0086] The haze of the film is preferably 5.0% or less, more preferably 4.0% or less, and even more preferably 3.0% or less. In this case, the film has sufficiently excellent transparency.

[0087] The coefficient of kinetic friction between the same films is preferably 0.2 or more and 0.7 or less. In this case, the surface lubricity becomes better, and the film is excellent in, for example, winding property. Further, in this case, it is possible to reduce surface conveyance scratches that may occur during film production.

Examples

[0088] (Example 1) Hereinafter, the present invention will be specifically illustrated by examples, but the present invention is not limited to the following examples beyond its gist.

[0089] [Measurement method] (5% weight loss temperature and 10% weight loss temperature) For the measurement of the 5% weight loss temperature and 10% weight loss temperature of the crosslinked acrylic resin, a differential thermal - thermogravimetric simultaneous measurement device "DTG - 60" manufactured by Shimadzu Corporation was used. Specifically, under a nitrogen flow (flow rate 300 ml / min), about 10 mg of the crosslinked acrylic resin sample was subjected to TG - DTA measurement while heating from room temperature to 500 °C at a rate of 10 °C / min, and the 5% weight loss temperature and 10% weight loss temperature were determined. The results are shown in Table 1.

[0090]

Table 1

[0091] (Glass transition temperature: Tg) The glass transition temperature of the polycarbonate resin composition was measured using a differential scanning calorimeter DSC6220 manufactured by SII NanoTechnology Inc. Specifically, about 10 mg of the polycarbonate resin composition sample was put into an aluminum sample pan manufactured by SII NanoTechnology Inc. and sealed, and the sample was heated from 30 °C to 250 °C at a heating rate of 20 °C / min under a nitrogen stream of 50 mL / min. After holding at this temperature for 3 minutes, it was cooled to 30 °C at a rate of 20 °C / min. Then, it was held at 30 °C for 3 minutes and heated again to 200 °C at a rate of 20 °C / min. The differential scanning calorimetry measurement curve (DSC data) obtained in the second heating (i.e., heating) was analyzed as the measurement curve. In the measurement curve, the temperature of the intersection point between the straight line obtained by extending the low - temperature side baseline to the high - temperature side and the tangent line drawn at the point where the gradient of the stepped change part of the glass transition is maximum (i.e., the extrapolated onset glass transition temperature) was determined, and this was taken as the glass transition temperature.

[0092] (Measurement of total light transmittance, haze) Using a turbidimeter COH400 manufactured by Nippon Denshoku Industries Co., Ltd., the total light transmittance and haze of films with a thickness of 40 μm and 60 μm prepared by the method described below were measured.

[0093] (YI value, ΔYI value) Using a spectrophotometer CM-5 manufactured by Konica Minolta, Inc., the initial YI value (i.e., pellet YI) of the pellet-shaped polycarbonate resin composition was measured in accordance with ASTM D1925. Also, the YI value of the pellet after a high-temperature durability test of holding at 100 °C for 200 hours was measured, and the value (ΔYI) obtained by subtracting the YI value of the pellet before the high-temperature durability test (initial pellet YI) from the YI value after this high-temperature durability test was determined.

[0094] (Coefficient of kinetic friction between film surfaces) For the measurement of the coefficient of kinetic friction between two film surfaces, COF-2-2N manufactured by IMADA Co., Ltd. and ZTS-5N of a digital force gauge were used. Specifically, the coefficient of kinetic friction between film surfaces was measured under the conditions of a load of 200 g, a sliding speed of 100 mm / min, and a sliding area of 63 × 63 mm.

[0095] (Appearance of film) The transparency and surface unevenness of the film were visually examined. If the film had transparency, a smooth surface, was not brittle and was flexible during handling, it was evaluated as "○". If the transparency was poor, particles (e.g., crosslinked acrylic resin) were non-uniformly dispersed and there were surface unevenness and poor smoothness, or it was brittle and easily cracked, it was evaluated as "×".

[0096] [Raw materials used] The abbreviations of the compounds used in the production examples and examples, and the manufacturers are as follows.

[0097] <Dihydroxy compound> ·ISB: Isosorbide (manufactured by Rocket Fluore Co., Ltd.) ·TCDDM: Tricyclodecane dimethanol (manufactured by OQ Chemicals Co., Ltd.)

[0098] <Carbonic acid diester> ·DPC: Diphenyl carbonate (manufactured by Mitsubishi Chemical Corporation)

[0099] <Catalyst deactivator> ·Phosphonic acid (manufactured by Tokyo Chemical Industry Co., Ltd.)

[0100] <Heat stabilizer (antioxidant)> ·Irganox 1010: Pentaerythritol - tetrakis(3-(3,5 - di - tert - butyl - 4 - hydroxyphenyl)propionate) (manufactured by BASF) <Additive> ·BMSA18 - GN (manufactured by Sekisui Chemical Co., Ltd.): Average particle diameter 0.8 μm ·Epstar MV1002: Average particle diameter 2.0 μm

[0101] <Example 1> (Production of polycarbonate resin) Using a continuous polymerization facility composed of three vertical stirring reactors, one horizontal stirring reactor, and a twin - screw extruder, the polymerization of polycarbonate resin was carried out. The three vertical stirring reactors were respectively referred to as the first vertical stirring reactor, the second vertical stirring reactor, and the third vertical stirring reactor, and the horizontal stirring reactor was referred to as the fourth horizontal stirring reactor. Specifically, first, ISB, TCDDM, and DPC were each melted in a tank, and ISB was continuously supplied to the first vertical stirring reactor at a flow rate of 27.3 kg / hr, TCDDM at 15.7 kg / hr, and DPC at 57.6 kg / hr (molar ratio of ISB / TCDDM / DPC = 0.700 / 0.300 / 1.010). At the same time, an aqueous solution of calcium acetate monohydrate, which is a polymerization catalyst, was supplied to the first vertical stirring reactor at an addition amount such that calcium acetate monohydrate was 1.5 μmol per 1 mol of all dihydroxy compounds. The internal temperature, internal pressure, and residence time of each reactor were respectively: the first vertical stirring reactor: 190 °C, 25 kPa, 120 minutes; the second vertical stirring reactor: 195 °C, 10 kPa, 90 minutes; the third vertical stirring reactor: 205 °C, 4 kPa, 45 minutes; the fourth horizontal stirring reactor: 220 °C, 0.1 - 1.0 kPa, 120 minutes. The operation was carried out while finely adjusting the internal pressure of the fourth horizontal stirring reactor so that the reduced viscosity of the obtained polycarbonate resin was 0.38 dL / g - 0.40 dL / g.

[0102] The polycarbonate resin withdrawn from the 4th horizontal stirred reactor was fed, while in a molten state, into a vented twin-screw extruder TEX30α manufactured by Nippon Steel Works, Ltd. The extruder has three vacuum vent ports (i.e., the 1st vent, the 2nd vent, and the 3rd vent), where residual low molecular weight components in the resin were removed by devolatilization. At the same time, phosphonic acid was added at 1.3 weight ppm to the polycarbonate resin as a catalyst deactivator in front of the 1st vent, and Irganox 1010 was added at 1000 weight ppm to the polycarbonate resin in front of the 3rd vent. The polycarbonate resin that passed through the extruder was then continuously passed, while in a molten state, through an Ultipleat® Candle Filter [manufactured by PALL Corporation] with a pore size of 10 μm to filter out foreign substances. Thereafter, the polycarbonate resin was extruded in a strand form from a die, cooled with water, solidified, and then pelletized by cutting with a rotary cutter to obtain the polycarbonate resin.

[0103] (Addition of Particles (Specifically, Crosslinked Acrylic Resin Particles) to the Polycarbonate Resin) Using a twin-screw extruder with a vacuum vent, the polycarbonate resin and various particles were melt-kneaded. BMSA18-GN was continuously supplied at 0.05 mass% to the resin composition to an extruder set at 240 °C, and melt-kneading was performed while removing volatile components and the like by vacuum from the vacuum vent port, and the mixture was discharged in a strand form from the die at the tip of the extruder to obtain pellets of the polycarbonate resin composition to which particles were added.

[0104] (Production of Film) The pellets of the polycarbonate resin composition obtained by the above-described method were vacuum-dried at 90 °C for 5 hours or more. Next, using a single-screw extruder (screw diameter: 30 mm, cylinder set temperature: 220 °C to 270 °C) manufactured by Technovel Corporation, the polycarbonate resin was extruded in film form from a T-die (width: 400 mm, set temperature: 200 to 270 °C) by a melt extrusion method. The extruded film was wound up in a roll shape while being cooled by a chill roll (set temperature: 100 to 170 °C) using a winder. In this way, unstretched films (surface protection films) with a film thickness of 60 μm and a film thickness of 40 μm were produced. Using each of these films, the various measurements and evaluations described above were performed. The results are shown in Table 2.

[0105] <Example 2> It was carried out in the same manner as in Example 1 except that the amount of the added particles was 0.1% by mass. The results are shown in Table 2.

[0106] <Example 3> It was carried out in the same manner as in Example 1 except that the amount of the added particles was 0.2% by mass. The results are shown in Table 2.

[0107] <Example 4> It was carried out in the same manner as in Example 1 except that the amount of the added particles was 0.4% by mass. The results are shown in Table 2.

[0108] <Example 5> It was carried out in the same manner as in Example 1 except that the amount of the added particles was 1.0% by mass. The results are shown in Table 2.

[0109] <Comparative Example 1> It was carried out in the same manner as in Example 1 except that no particles were added. The results are shown in Table 3. Note that the obtained film had poor surface lubricity and the coefficient of kinetic friction could not be measured by the method described above, so it was marked as "unmeasurable".

[0110] <Comparative Example 2> It was carried out in the same manner as in Example 1 except that the type of the added particles was changed to Epistar MV1002. The results are shown in Table 3.

[0111] <Comparative Example 3> It was carried out in the same manner as in Example 1 except that the type of the added particles was changed to Epistar MV1002 and the addition amount was 0.1% by mass. The results are shown in Table 3.

[0112] <Comparative Example 4> It was carried out in the same manner as in Example 1 except that the type of the added particles was changed to Epistar MV1002 and the addition amount was 0.2% by mass. The results are shown in Table 3.

[0113] <Comparative Example 5> It was carried out in the same manner as in Example 1 except that the type of the added particles was changed to Epistar MV1002 and the addition amount was 0.4% by mass. The results are shown in Table 3.

[0114] <Comparative Example 6> It was carried out in the same manner as in Example 1 except that the type of the added particles was changed to Epistar MV1002 and the addition amount was 1.0% by mass. The results are shown in Table 3.

[0115]

Table 2

[0116]

Table 3

[0117] As understood from Table 2, it can be seen that the film composed of the polycarbonate resin composition containing the specific polycarbonate resin and the specific crosslinked acrylic resin is excellent in transparency, heat resistance, and surface smoothness, and coloring is suppressed.

[0118] In contrast, Comparative Example 1 did not contain a crosslinked acrylic resin, so its surface lubricity was poor. Further, in Comparative Examples 2 to 6, the 10% weight loss temperature of the crosslinked acrylic resin was too low and the average particle diameter was too large. Therefore, as the amount of the crosslinked acrylic resin increased, haze tended to increase, resulting in insufficient transparency, or the YI value increased and the color tone of the resin composition deteriorated.

[0119] From the above results, it can be seen that a film composed of a polycarbonate resin containing a structural unit (A) represented by the above formula (1) and a structural unit (B) derived from one or more dihydroxy compounds selected from the group consisting of dihydroxy compounds of aliphatic hydrocarbons, dihydroxy compounds of alicyclic hydrocarbons, and ether-containing dihydroxy compounds, and a polycarbonate resin composition containing a crosslinked acrylic resin having a 10% weight loss temperature of 325°C or higher in air realizes a film excellent in transparency, heat resistance, surface lubricity, and suppressed coloring.

Claims

1. A polycarbonate resin comprising a structural unit (A) represented by the following formula (1) and a structural unit (B) derived from one or more dihydroxy compounds selected from the group consisting of dihydroxy compounds of aliphatic hydrocarbons, dihydroxy compounds of alicyclic hydrocarbons, and ether-containing dihydroxy compounds, and A film composed of a polycarbonate resin composition containing a crosslinked acrylic resin having a 10% weight loss temperature in air of 325°C or higher. 【Chemical 1】

2. The film according to Claim 1, wherein the structural unit (B) is a structural unit derived from a dihydroxy compound of an alicyclic hydrocarbon.

3. The film according to Claim 2, wherein the structural unit derived from the dihydroxy compound of the alicyclic hydrocarbon is a structural unit represented by the following formula (2). [Chemical 2]

4. The film according to Claim 1, wherein the crosslinked acrylic resin is in the form of particles and the average particle diameter of the crosslinked acrylic resin is 0.5 μm or more and less than 2.0 μm.

5. The film according to Claim 1, wherein the content of the crosslinked acrylic resin is 0.05% by mass or more and less than 3.0% by mass based on 100% by mass of the polycarbonate resin composition.

6. The film according to Claim 1, wherein the glass transition temperature of the polycarbonate resin composition is 110°C or higher and 150°C or lower.

7. A surface protection film comprising the film according to any one of Claims 1 to 6.

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