Resin composition and liquid for film production based on solution casting method
阅读说明：本技术 基于溶液流延法的膜制造用树脂组合物和液体 (Resin composition and liquid for film production based on solution casting method ) 是由 北山史延 上村拓也 于 2019-01-21 设计创作，主要内容包括：本发明提供一种树脂组合物,是基于溶液流延法的树脂膜的制造中使用的树脂组合物,在具有优异的耐热性的同时,利用溶液流延法使溶剂从流延膜蒸发时该溶剂的挥发速度快的、包含甲基丙烯酸系聚合物。在包含甲基丙烯酸系聚合物(a)的、基于溶液流延法的膜制造用树脂组合物中,上述甲基丙烯酸系聚合物(a)是由甲基丙烯酸甲酯单元和1种以上的干燥促进性共聚单体单元构成的共聚物,且玻璃化转变温度为110℃以上。上述干燥促进性共聚单体单元优选为选自N－取代马来酰胺系单体单元、酯部位为碳原子数2～8的伯或仲烃基或芳香族系烃基即甲基丙烯酸酯单元、酯部位具有缩合环结构的碳原子数7～16的饱和烃基即甲基丙烯酸酯单元、酯部位包含醚键的直链状或分支状的基团即甲基丙烯酸酯单元、以及苯乙烯系单体单元。(The present invention provides a resin composition used for producing a resin film by a solution casting method, which has excellent heat resistance and a high solvent volatilization rate when a solvent is evaporated from a casting film by the solution casting method, and which contains a methacrylic polymer. In a resin composition for film production by a solution casting method, which contains a methacrylic polymer (a), the methacrylic polymer (a) is a copolymer composed of a methyl methacrylate unit and 1 or more kinds of drying accelerating comonomer units, and has a glass transition temperature of 110 ℃ or higher. The drying-accelerating comonomer unit is preferably selected from the group consisting of an N-substituted maleimide monomer unit, a methacrylate ester unit having an ester portion of a primary or secondary hydrocarbon group having 2 to 8 carbon atoms or an aromatic hydrocarbon group, a methacrylate ester unit having an ester portion of a saturated hydrocarbon group having 7 to 16 carbon atoms and a condensed ring structure, a methacrylate ester unit having an ester portion of a linear or branched group containing an ether bond, and a styrene monomer unit.)
1. A resin composition for film production by a solution casting method, comprising a methacrylic polymer (a) which is a copolymer comprising a methyl methacrylate unit and 1 or more kinds of drying-accelerating comonomer units and has a glass transition temperature of 110 ℃ or higher.
2. The resin composition for film production according to claim 1, wherein the glass transition temperature is 112 ℃ or higher.
3. The resin composition for film production according to claim 1 or 2, wherein the drying-accelerating comonomer unit is at least 1 selected from the group consisting of an N-substituted maleimide monomer unit, a methacrylate ester unit having an ester moiety of a primary or secondary hydrocarbon group having 2 to 8 carbon atoms or an aromatic hydrocarbon group, a methacrylate ester unit having an ester moiety of a saturated hydrocarbon group having 7 to 16 carbon atoms and having a condensed ring structure, a methacrylate ester unit having an ester moiety of a linear or branched group including an ester bond, and a styrene monomer unit.
4. The resin composition for film production according to any one of claims 1 to 3, wherein the condensed ring structure is a structure in which 2 five-membered rings are condensed by 3 carbon atoms in series.
5. The film-producing resin composition according to any one of claims 1 to 4, wherein the drying-accelerating comonomer unit comprises at least 1 of an N-substituted maleimide monomer unit and a methacrylate ester unit having an ester moiety of a saturated hydrocarbon group having 7 to 16 carbon atoms and having a condensed ring structure.
6. The film-producing resin composition according to claim 5, wherein the methacrylic polymer (a) further comprises a drying-accelerating comonomer unit other than the N-substituted maleimide monomer unit and a methacrylate ester unit having an ester moiety of a saturated hydrocarbon group having 7 to 16 carbon atoms and having a condensed ring structure, and/or a comonomer unit other than the drying-accelerating comonomer unit.
7. The film-producing resin composition according to any one of claims 1 to 6, wherein the proportion of the methyl methacrylate units in all monomer units constituting the methacrylic polymer (a) is 70 to 99% by weight, and the proportion of the drying-accelerating comonomer units is 1 to 30% by weight.
8. The film-producing resin composition according to any one of claims 1 to 7, wherein the methacrylic polymer (a) has a weight-average molecular weight of 40 to 400 ten thousand.
9. The film-producing resin composition according to any one of claims 1 to 8, further comprising a graft copolymer (b) having a core layer and a shell layer.
10. A liquid for film production based on a solution casting method, comprising the resin composition for film production of any one of claims 1 to 9 and a solvent (c).
11. The liquid according to claim 10, wherein the solvent (c) comprises a solvent (c-1) having a Hansen solubility parameter with a hydrogen key value H of 1 to 12 and a solvent (c-2) having a H of 14 to 24, and the weight ratio of the solvent (c-1) to the solvent (c) as a whole is 55 to 95 wt%.
12. A method for producing a resin film by a solution casting method, comprising the step of casting the liquid according to claim 10 or 11 onto a surface of a support, and then evaporating the solvent.
13. A resin film formed from the liquid of claim 10 or 11.
14. The resin film according to claim 13, wherein the resin film has a thickness of 10 to 500 μm.
15. The resin film according to claim 13 or 14, which is a film for lamination protection to the surface of another substrate.
16. The resin film according to claim 13 or 14, wherein the resin film is an optical film.
17. The resin film according to claim 16, wherein the optical film is a polarizer protective film.
18. A polarizing plate comprising a polarizer and the resin film according to claim 17 laminated thereon.
19. A display device comprising the polarizing plate according to claim 18.
Technical Field
The present invention relates to a resin composition containing a methacrylic polymer for use in producing a film by a solution casting method, and a liquid thereof.
Background
Methacrylic polymers are excellent polymers used in a large number of fields in industry because they are excellent in transparency, hue, appearance, weather resistance, gloss and processability. In particular, films formed from methacrylic polymers are used for various applications such as interior and exterior materials for automobiles, exterior materials for electronic products such as cellular phones and smartphones, interior and exterior materials for civil engineering and construction such as beds, windows, interior and exterior walls, lighting sections, and road signs, because they exhibit excellent transparency, appearance, and weather resistance. In recent years, methacrylic polymers have been used for optical members such as liquid crystal display devices and organic EL display devices because of their excellent optical properties.
As a method for producing a high-quality resin film, a melt extrusion method using a T die, a solution casting method in which a liquid in which a resin is dissolved in a solvent is cast on a support surface, and then the solvent is evaporated to form a film, and the like are known. In the melt extrusion method using a T die, there is a disadvantage that a difference in physical properties between the extrusion direction and the direction perpendicular thereto is easily generated in the obtained film, and the residual alignment is easily generated. On the other hand, in the solution casting method, since no physical pressure is applied to the film, alignment of the polymer does not occur, and there is a merit that directionality does not occur in the strength, optical characteristics, and the like of the film. In addition to extremely high thickness accuracy of the film, the heat applied to the resin is low, and the amount of the heat stabilizer or the like added can be reduced.
Patent document 1 describes a technique for forming a film from a laminate having a layer containing an acrylic resin as a main component and a layer containing a cellulose acylate resin as a main component by a solution casting method, as a method for producing an optical film by stretching the laminate.
Patent document 1: japanese patent laid-open No. 2014-24254.
Disclosure of Invention
In the example of patent document 1, as the acrylic resin, polymethyl methacrylate resin is used. However, there is a problem that after a liquid in which a polymethyl methacrylate resin is dissolved in a solvent is cast on a support surface to form a casting film containing the solvent, when the solvent is evaporated from the casting film, time is required for the evaporation of the solvent, and the productivity of the film is lowered.
The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a resin composition used for producing a resin film by a solution casting method, which has excellent heat resistance and in which a solvent is volatilized at a high speed when the solvent is evaporated from a cast film by the solution casting method, and a liquid containing the resin composition.
The present inventors have found that the above problems can be solved by copolymerizing a specific copolymer in a methacrylic polymer mainly composed of methyl methacrylate, and have completed the present invention.
That is, the first invention relates to a resin composition for film production, which is a resin composition for film production by a solution casting method, comprising a methacrylic polymer (a) which is a copolymer composed of a methyl methacrylate unit and 1 or more kinds of drying-accelerating comonomer units and has a glass transition temperature of 110 ℃ or higher. The glass transition temperature is preferably 112 ℃ or higher.
The drying-accelerating comonomer unit is preferably at least 1 selected from the group consisting of an N-substituted maleimide monomer unit, a methacrylate ester unit having an ester portion of a primary or secondary hydrocarbon group having 2 to 8 carbon atoms or an aromatic hydrocarbon group, a methacrylate ester unit having an ester portion of a saturated hydrocarbon group having 7 to 16 carbon atoms and having a condensed ring structure, a methacrylate ester unit having an ester portion of an ether-bonded linear or branched group, and a styrene monomer unit. The condensed ring structure is preferably a structure in which 2 five-membered rings are condensed by 3 carbon atoms in succession. More preferably, the drying-accelerating comonomer unit contains at least 1 of an N-substituted maleimide monomer unit and a methacrylate ester unit having an ester moiety of a saturated hydrocarbon group having 7 to 16 carbon atoms and having a condensed ring structure. In this case, the methacrylic polymer (a) may further contain a drying-accelerating comonomer unit other than the N-substituted maleimide monomer unit and a methacrylate ester unit having an ester moiety of a saturated hydrocarbon group having 7 to 16 carbon atoms and having a condensed ring structure, and/or a comonomer unit other than the drying-accelerating comonomer unit.
Preferably, the proportion of the methyl methacrylate unit in the total monomer units constituting the methacrylic polymer (a) is 70 to 99% by weight, and the proportion of the drying-accelerating comonomer unit is 1 to 30% by weight. The weight average molecular weight of the methacrylic polymer (a) is preferably 40 to 400 ten thousand.
The resin composition for film production of the present invention may further comprise a graft copolymer (b) having a core layer and a shell layer.
The second invention relates to a liquid for film production based on a solution casting method, comprising the first resin composition for film production according to the invention and a solvent (c). Preferably, the solvent (c) contains a solvent (c-1) having a hydrogen bond H of 1 to 12 in a Hansen solubility parameter and a solvent (c-2) having an H of 14 to 24, and the weight ratio of the solvent (c-1) to the entire solvent (c) is 55 to 95 wt%.
The third invention relates to a method for producing a resin film by a solution casting method, comprising a step of casting the liquid of the second invention on a support surface and then evaporating a solvent.
The fourth invention relates to a resin film formed from the liquid according to the second invention. The thickness of the resin film is preferably 10 to 500 μm. The resin film may be a protective film laminated on the surface of another substrate, and may be an optical film. The optical film is preferably a polarizer protective film.
The fifth invention relates to a polarizing plate obtained by laminating a polarizing plate and the resin film, and a display device including the polarizing plate.
According to the present invention, it is possible to provide a resin composition used for producing a resin film by a solution casting method, which has excellent heat resistance and a high solvent evaporation rate when a solvent is evaporated from a cast film by the solution casting method, and which contains a methacrylic polymer, and a liquid containing the resin composition. When a resin film is produced by a solution casting method using the liquid, the solvent is quickly volatilized, and thus the productivity of the film can be improved. The resin film obtained has an advantage of excellent heat resistance.
Detailed Description
Hereinafter, embodiments of the present invention will be described in detail, but the present invention is not limited to these embodiments.
(resin composition)
The resin composition of the present invention is a resin composition mainly composed of a methacrylic polymer (a), and is used as a constituent resin based on a liquid used in the production of a resin film by a solution casting method. First, the methacrylic polymer (a) will be explained.
(methacrylic acid Polymer (a))
The methacrylic polymer (a) contained in the resin composition of the present invention is a copolymer composed of a methyl methacrylate unit and 1 or more kinds of drying accelerating comonomer units. By copolymerizing 1 or more kinds of the drying-accelerating comonomer units with the methyl methacrylate units, the volatilization rate of the solvent can be accelerated when the solvent is evaporated from the casting film by the solution casting method, as compared with polymethyl methacrylate which is a homopolymer composed only of methyl methacrylate units.
Such a drying-accelerating comonomer unit is preferably a comonomer unit which does not significantly reduce the heat resistance of the methacrylic polymer (a). The drying-accelerating comonomer unit capable of forming the methacrylic polymer (a) having good heat resistance is preferably at least 1 selected from the group consisting of an N-substituted maleimide monomer unit, a methacrylate ester unit which is a primary or secondary hydrocarbon group having 2 to 8 carbon atoms in the ester portion or an aromatic hydrocarbon group, a methacrylate ester unit which is a saturated hydrocarbon group having 7 to 16 carbon atoms and a condensed ring structure in the ester portion, a methacrylate ester unit which is a linear or branched group having an ether bond in the ester portion, and a styrene monomer unit. When these drying-accelerating comonomer units are used, the excellent heat resistance of the methacrylic polymer is obtained, and the speed of solvent evaporation from the casting film in the solution casting method can be accelerated.
Examples of the N-substituted maleimide monomer include N-phenyl maleimide, N-benzyl maleimide, N-cyclohexyl maleimide, and N-methyl maleimide. Among these, preferred are maleimide monomer units having a cyclic substituent on the N atom, that is, preferred are N-phenyl maleimide, N-benzyl maleimide and N-cyclohexyl maleimide.
Examples of the methacrylic acid ester having an ester moiety of a primary or secondary hydrocarbon group having 2 to 8 carbon atoms or an aromatic hydrocarbon group include ethyl methacrylate, propyl methacrylate, n-butyl methacrylate, hexyl methacrylate, cyclohexyl methacrylate, 2-ethylhexyl methacrylate, octyl methacrylate, phenyl methacrylate, benzyl methacrylate, and the like. Among them, ethyl methacrylate, n-butyl methacrylate, cyclohexyl methacrylate, 2-ethylhexyl methacrylate and benzyl methacrylate are preferable.
Examples of the methacrylic acid ester which is a saturated hydrocarbon group having 7 to 16 carbon atoms and having a condensed ring structure in the ester portion include dicyclopentanyl methacrylate and isobornyl methacrylate. The number of carbon atoms of the saturated hydrocarbon group is preferably 8 to 14, more preferably 9 to 12. The condensed ring structure is not particularly limited, but is preferably a structure in which 2 five-membered rings are condensed from consecutive 3 carbon atoms.
Examples of the methacrylate ester as a linear or branched group having an ether bond in the ester portion include 2-methoxyethyl methacrylate and the like.
As the styrene monomer, for example, styrene, α -methylstyrene, monochlorostyrene, dichlorostyrene and the like are preferable. Among them, styrene is preferable.
In order to increase the rate of solvent evaporation from the cast film in the solution casting method and to improve the heat resistance of the methacrylic polymer, the drying-accelerating comonomer unit preferably contains at least 1 of an N-substituted maleimide monomer unit and a methacrylate ester unit which is a saturated hydrocarbon group having 7 to 16 carbon atoms and having a condensed ring structure at the ester portion.
In this case, the drying-accelerating comonomer units may be at least 1 selected from the group consisting of N-substituted maleimide monomer units and methacrylate ester units which are saturated hydrocarbon groups having 7 to 16 carbon atoms and having a condensed ring structure in the ester portion, or may be at least 1 selected from the group consisting of N-substituted maleimide monomer units, methacrylate ester units which are saturated hydrocarbon groups having 7 to 16 carbon atoms and having a condensed ring structure in the ester portion, and other drying-accelerating comonomer units. By using these compounds in combination, the heat resistance of the methacrylic polymer and the volatilization rate of the solvent can be adjusted to improve both of them in a well-balanced manner.
The N-substituted maleimide monomer units and the drying-accelerating comonomer units other than the methacrylate ester units, which are saturated hydrocarbon groups having 7 to 16 carbon atoms and having a condensed ring structure at the ester position, may be at least 1 selected from the group consisting of methacrylate ester units, which are primary or secondary hydrocarbon groups having 2 to 8 carbon atoms at the ester position, or aromatic hydrocarbon groups, methacrylate ester units, which are linear or branched groups having an ether bond at the ester position, and styrene monomer units.
The proportion of the methyl methacrylate unit in the total monomer units constituting the methacrylic polymer (a) is preferably 70 to 99% by weight, more preferably 75 to 98% by weight, and still more preferably 80 to 97% by weight. The proportion of the drying-accelerating comonomer unit in the total monomer units constituting the methacrylic polymer (a) is preferably 1 to 30% by weight, more preferably 2 to 25% by weight, and still more preferably 3 to 20% by weight. When the drying-accelerating comonomer unit contains 2 or more species, the proportion of the drying-accelerating comonomer unit means the proportion of the total amount of all the drying-accelerating comonomer units contained in the total monomer units. By setting such a weight ratio, the solvent volatilization rate in the solution casting method can be accelerated while having excellent heat resistance. The weight ratio of each unit can be determined by proton nuclear magnetic resonance spectroscopy.
The methacrylic polymer (a) may be a copolymer containing no other comonomer unit corresponding to the drying-accelerating comonomer unit, or may be a copolymer containing another comonomer unit not corresponding to the drying-accelerating comonomer unit. Examples of such other copolymers include methacrylates such as stearyl methacrylate, glycidyl methacrylate, epoxycyclohexylmethyl methacrylate, dimethylpropylethyl methacrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, 2,2, 2-trifluoroethyl methacrylate, 2,2, 2-trichloroethyl methacrylate, methacrylamide, and N-methylolmethacrylamide; acrylic esters such as methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, octyl acrylate, glycidyl acrylate, epoxycyclohexylmethyl acrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, acrylamide, and N-methylolacrylamide; carboxylic acids such as methacrylic acid and acrylic acid and salts thereof; vinyl amines such as acrylonitrile and methacrylonitrile; maleic acid, fumaric acid, and esters thereof; halogenated vinyls such as chlorinated vinyl, brominated vinyl, and chloroprene; vinyl esters such as vinyl formate, vinyl acetate and vinyl propionate; olefins such as ethylene, propylene, butylene, butadiene and isobutylene. The proportion of such other comonomer units in the total monomer units constituting the methacrylic polymer (a) is preferably 10% by weight or less, more preferably 8% by weight or less, and still more preferably 5% by weight or less.
From the viewpoint of processability and appearance, the methacrylic polymer (a) is preferably not contained, and the polyfunctional monomer such as aryl methacrylate, diaryl phthalate, triarylisocyanate, monoethylene glycol dimethacrylate, tetraethylene glycol dimethacrylate or divinylbenzene is preferably not contained.
The weight average molecular weight of the methacrylic polymer (a) is not particularly limited, and is preferably 40 to 400 ten thousand. When the weight average molecular weight is within this range, not only the viscosity of the liquid is preferable for the solution casting method, but the obtained film is tough and easy to handle when the film is used for various applications. More preferably 80 to 350 ten thousand, and still more preferably 100 to 300 ten thousand. The weight average molecular weight can be calculated by standard polystyrene conversion using permeation chromatography (GPC).
The methacrylic polymer (a) has excellent heat resistance. In the present invention, the glass transition temperature is used as an index indicating the heat resistance. The methacrylic polymer (a) has a glass transition temperature of 110 ℃ or higher. The glass transition temperature of the methacrylic polymer (a) may be adjusted to fall within the above range by adjusting the kind of the drying accelerating comonomer unit to be used, or by adjusting the combination of 2 or more kinds of the units, the ratio of the units in the whole resin, and the like. The glass transition temperature is preferably 112 ℃ or higher, more preferably 114 ℃ or higher, still more preferably 117 ℃ or higher, yet more preferably 119 ℃ or higher, particularly preferably 122 ℃ or higher, and most preferably 125 ℃ or higher.
In the production of the methacrylic polymer (a), a known polymerization method such as suspension polymerization, emulsion polymerization, bulk polymerization, or solution polymerization can be used.
(graft copolymer (b))
The resin composition of the present invention may further comprise a graft copolymer (b) having a core layer and a shell layer. The graft copolymer is excellent in thermal stability, can impart excellent transparency and hue to a resin film made of the resin composition of the present invention, and can improve mechanical strength such as bending resistance and crack resistance.
The graft copolymer (b) of the present invention is referred to as a multistage polymer, a multilayer structure polymer, or a shell-core type polymer. These polymers are polymers having a polymer layer (shell layer) obtained by polymerizing a monomer mixture in the presence of crosslinked polymer particles (core layer). The core layer and the shell layer may be composed of 1 layer or 2 or more layers. The graft copolymer (b) is not particularly limited, and a known copolymer can be suitably used. As an example, there is a graft copolymer obtained by polymerizing a monomer mixture containing an acrylic ester as a main component with a crosslinking agent to form an acrylic ester-based rubbery polymer and polymerizing a monomer mixture containing a methacrylic ester as a main component in the presence of the acrylic ester-based rubbery polymer. The graft copolymer can be produced by ordinary emulsion polymerization using a known emulsifier.
When the resin composition of the present invention contains the graft copolymer (b), the blending ratio of the methacrylic polymer (a) and the graft copolymer (b) varies depending on the use of the film, but the blending amount of the methacrylic polymer (a) is preferably 30 to 98 parts by mass, the blending amount of the graft copolymer (b) is preferably 70 to 2 parts by mass, more preferably 50 to 95 parts by mass, the blending amount of the graft copolymer (b) is 50 to 5 parts by mass, particularly preferably 60 to 90 parts by mass, and the blending amount of the graft copolymer (b) is 40 to 10 parts by mass, based on 100 parts by mass of the total of the blending amounts of the two components. When the amount of the methacrylic polymer (a) is 30 parts by mass or more, the properties of the methacrylic polymer (a) can be sufficiently exhibited, and when the amount is 98 parts by mass or less, the mechanical strength of the methacrylic polymer can be sufficiently improved by the addition of the graft copolymer (b).
(other Components)
The resin composition of the present invention may contain, as appropriate, known additives such as a light stabilizer, an ultraviolet absorber, a heat stabilizer, a decolorizer, a light diffuser, a colorant, a dye, a pigment, an antistatic agent, a heat ray reflective material, a lubricant, a plasticizer, an ultraviolet absorber, a stabilizer, and a filler, and other resins such as a styrene resin such as an acrylonitrile styrene resin and a styrene maleic anhydride resin, a fluorine resin such as a polycarbonate resin, a polyvinyl acetal resin, a cellulose acylate resin, a vinylidene fluoride resin, and a polyfluorinated alkyl (meth) acrylate resin, a silicone resin, a polyolefin resin, a polyethylene terephthalate resin, and a polybutylene terephthalate resin.
The resin composition of the present invention may suitably contain inorganic fine particles having birefringence described in patent nos. 3648201 and 4336586 and a low molecular weight compound having birefringence described in patent No. 3696649 and having a molecular weight of 5000 or less, preferably 1000 or less, for the purpose of adjusting the alignment birefringence of the formed film.
The mode of the resin composition of the present invention is not particularly limited. The powder or granule can be used.
(liquid)
The liquid of the present invention contains at least the resin composition of the present invention and the solvent (c), and is a liquid for producing a resin film by a solution casting method. In the liquid of the present invention, the methacrylic polymer (a) and other components are dissolved or dispersed in the solvent (c). Other components including the graft copolymer may be contained in the resin composition of the present invention, or components different from the resin composition of the present invention may be added to the solvent at the stage of producing the liquid.
(solvent)
The solvent (c) contained in the liquid of the present invention is not particularly limited as long as it can dissolve or disperse the methacrylic polymer (a) and other components, and is preferably a solvent (c-1) containing hydrogen bonds H having a Hansen solubility parameter of 1 to 12. By forming a liquid using such a solvent, good solubility or dispersibility in the solvent for the methacrylic polymer (a) can be achieved. The hydrogen bond H is preferably a solvent having a value of 3 to 10, more preferably a solvent having a value of 5 to 8.
Conventionally, as an index indicating the solubility of a substance, a solubility parameter (SP value) is known, and it is proposed that the coagulation energy item of the SP value is divided by the kind of interaction energy (London dispersion force, dipole force, hydrogen bond force) acting between molecules, and these are respectively used as hansen solubility parameters indicated by a London dispersion force item, an inter-dipole force item, and a hydrogen bond force item. In the present invention, the hydrogen bond term H in the hansen solubility parameter is used as an index of the solubility of the methacrylic polymer (a) and the graft copolymer (b) when they are dissolved in a solvent. Through research, the inventors found that the numerical value of the hydrogen bond is higher in association with the solubility of the methacrylic polymer (a) in the solvent than the London dispersion force project and the inter-dipole force project, and the hydrogen bond can be used as an index representing the solubility. The details of the hydrogen bond item H can be found in, for example, yaobaxiu, entitled "use special set: polymer phase dissolution design 1. solubility evaluation of Hansen solubility parameters (HSP values) ", technique for bonding, vol.34no.3(2014) web 116) pages 1-8.
Examples of the solvent (c-1) having a hydrogen bond item H of 1 to 12 include 1, 4-bis
Among these solvents, methyl ethyl ketone, chloroform, and methylene chloride are preferable, and methylene chloride is more preferable, because methacrylic polymer (a) has excellent solubility and a high volatilization rate.
The solvent contained in the liquid of the present invention may be composed of only the solvent (c-1) having the hydrogen bond item H of 1 to 12. However, in view of improvement in film formability, film releasability, workability, etc. at the time of solution casting, it is preferred that solvent (c-1) having hydrogen bonding in an amount of 1 to 12 and solvent (c-2) having H in an amount of 14 to 24 are contained.
Examples of the solvent (c-2) having an H of 14 to 24 include methanol (22.3), ethanol (19.4), isopropanol (16.4), butanol (15.8), and ethylene glycol monoethyl ether (14.3). These solvents may be used alone in 1 kind, or may be used in combination of 2 or more kinds.
When used in combination with the solvent (c-2) having an H content of 14 to 24, the solvent (c-1) having an H content of 1 to 12 is contained in an amount of preferably 55 to 95% by weight, more preferably 60 to 90% by weight, further preferably 65 to 85% by weight, further preferably 70 to 85% by weight, based on the whole amount of the solvent (c) contained in the liquid.
The proportion of the resin component (the total amount of the methacrylic polymer (a) and the graft copolymer (b)) in the liquid of the present invention is not particularly limited, and may be suitably determined in consideration of solubility or dispersibility of the methacrylic polymer (a) and the graft copolymer (b) in the solvent used, conditions for carrying out the solution casting method, and the like, and is preferably 5 to 50% by weight, more preferably 10 to 45% by weight, and still more preferably 15 to 40% by weight. The liquid of the present invention may contain the graft copolymer (b) and other components.
(solution casting method)
The liquid of the present invention is used for manufacturing a resin film according to a solution casting method. Specifically, the liquid of the present invention is cast on the surface of a support, and then the solvent is evaporated to produce a resin film.
The following describes an embodiment of the solution casting method of the present invention, but the present invention is not limited thereto. First, pellets containing the methacrylic polymer (a), the graft copolymer (b) and optionally the other components are prepared, and then the pellets are mixed with the solvent (c) to prepare a liquid in which the components are dissolved and dispersed in the solvent (c). Alternatively, the methacrylic polymer (a) and the graft copolymer (b) may be mixed with the solvent (c) simultaneously or sequentially to dissolve the components in the solvent (c). Alternatively, 2 or more kinds of liquid preparation solutions are prepared by mixing the methacrylic polymer (a) and the graft copolymer (b) with the solvent (c), and the liquid preparation solutions are mixed to prepare a liquid. These dissolving steps can be carried out by appropriately adjusting the temperature and pressure. Among them, there is a case of a method in which pellets containing the methacrylic polymer (a) and the graft copolymer (b) and, in some cases, the other components are prepared and then dissolved and dispersed in the solvent (c). The resulting liquid may be filtered or deaerated after the above dissolving step.
Then, the liquid is sent to a pressure die by a liquid sending pump, and the liquid is cast on the surface (mirror surface) of a support such as an endless belt or a drum made of metal or synthetic resin from a slit of the pressure die, thereby forming a liquid film.
The formed liquid film is heated on the support to evaporate the solvent to form a film. The conditions for evaporating the solvent may be appropriately determined depending on the boiling point of the solvent used.
The obtained film was peeled from the surface of the support. The obtained film may be subjected to a drying step, a heating step, a stretching step, and the like as appropriate.
(resin film)
The resin film of the present invention is formed by a solution casting method using the above liquid. The thickness of the film is not particularly limited, but is preferably 500 μm or less, more preferably 300 μm or less, and particularly preferably 200 μm or less. Moreover, it is preferably 10 μm or more, more preferably 30 μm or more, further preferably 50 μm or more, and particularly preferably 60 μm or more. When the film thickness is within the above range, the film is not likely to be deformed during vacuum forming, and the deep-drawn portion is not likely to be broken, and a film having uniform optical properties and good transparency can be produced. On the other hand, if the film thickness exceeds the above range, the cooling of the film after molding becomes uneven, and the optical characteristics tend to become uneven. If the film thickness is less than the above range, handling of the film may become difficult.
The resin film of the present invention has a total light transmittance of preferably 85% or more, more preferably 88% or more, and further preferably 90% or more, when measured at a film thickness of 80 μm. When the total light transmittance is in the above range, the transparency is high, and therefore, light-transmitting optical parts, decorative applications, interior decoration applications, and vacuum molding applications are required.
The resin film of the present invention has a glass transition temperature of preferably 90 ℃ or higher, more preferably 100 ℃ or higher, still more preferably 110 ℃ or higher, yet more preferably 115 ℃ or higher, particularly preferably 120 ℃ or higher, and most preferably 124 ℃ or higher. When the glass transition temperature is within the above range, a resin film having excellent heat resistance can be obtained.
The resin film of the present invention has a haze of preferably 2.0% or less, more preferably 1.5% or less, still more preferably 1.3% or less, and particularly preferably 1.0% or less, when measured at a film thickness of 80 μm. The internal haze of the film is preferably 1.5% or less, more preferably 1.0% or less, still more preferably 0.5% or less, and particularly preferably 0.3% or less. When the haze and the internal haze are in the above ranges, the transparency is high, and therefore, the optical member is suitable for optical parts, decoration applications, interior decoration applications, and vacuum molding applications, which require light transmittance. The haze is constituted by the haze in the film and on the film surface (outside), and these are expressed as the internal haze and the external haze.
The resin film of the present invention can also be used as an optical film. In particular, when used as a polarizer protective film, the optical anisotropy is preferably small. In particular, it is preferable that the optical anisotropy in the in-plane direction (longitudinal direction and width direction) of the film is small, and the optical anisotropy in the thickness direction is also small. That is, the absolute values of the in-plane retardation and the thickness direction retardation are preferably small. More specifically, the absolute value of the in-plane retardation is preferably 10nm or less, more preferably 6nm or less, still more preferably 5nm or less, and particularly preferably 3nm or less. The absolute value of the retardation in the thickness direction is preferably 50nm or less, more preferably 20nm or less, further preferably 15nm or less, further preferably 10nm or less, and most preferably 5nm or less. Such a film having a retardation can be suitably used as a polarizer protective film provided in a polarizing plate of a liquid crystal display device. On the other hand, when the absolute value of the in-plane retardation of the film exceeds 10nm or the absolute value of the thickness direction retardation exceeds 50nm, there is a problem that when the film is used as a polarizer protective film provided in a polarizing plate of a liquid crystal display device, a decrease in contrast occurs in the liquid crystal display device.
The retardation is an index value calculated based on the birefringence, and the in-plane retardation (Re) and the thickness direction retardation (RTh) can be calculated by the following equations. In the ideal film which is a perfect optical equivalent for the three-dimensional direction, the in-plane retardation Re and the thickness direction retardation RTh are both 0.
Re＝(nx－ny)×d
RTh＝((nx+ny)/2－nz)×d
In the above formulae, nx, ny, and nz represent refractive indices in respective axial directions, with the stretching direction (the alignment direction of polymer chains) being an X axis, the direction perpendicular to the X axis being a Y axis, and the thickness direction of the film being a Z axis, in the plane. And d represents the thickness of the film and nx-ny represents the alignment birefringence. The MD direction of the film is defined as the X axis, but the stretching direction is defined as the X axis when the film is stretched.
The resin film of the present invention preferably has an alignment birefringence value of-2.6 × 10－4～2.6×10－4More preferably-2.1 × 10－4～2.1×10－4Still more preferably-1.7 × 10－4～1.7×10－4Still more preferably-1.6 × 10－4～1.6×10－4Still more preferably-1.5 × 10－4～1.5×10－4Still more preferably-1.0 × 10－4～1.0×10－4Particularly preferably-0.5 × 10－4～0.5×10－4Most preferably-0.2 × 10－4～0.2×10－4. If the alignment birefringence is in the above range, the molding can be performed without causing the moldingWhen the birefringence is increased during processing, stable optical characteristics are obtained. And is also suitable for use as an optical film for use in liquid crystal displays and the like.
(stretching)
The resin film of the present invention has high toughness and high flexibility as an unstretched film, but can be further stretched to improve the mechanical strength and the film thickness accuracy of the resin film.
When the resin film of the present invention is stretched, the resin composition of the present invention is temporarily formed into a film in an unstretched state, and then uniaxially or biaxially stretched, or in the film formation, a stretching operation is appropriately performed along with the progress of the steps of film formation and solvent degassing, whereby a stretched film (uniaxially or biaxially stretched film) can be produced. It is also possible to appropriately combine stretching in film formation and stretching after film formation.
The stretch ratio of the stretched film is not particularly limited, and may be determined depending on the mechanical strength, surface properties, thickness accuracy, and the like of the produced stretched film. The stretching ratio is generally selected preferably in the range of 1.1 to 5 times, more preferably in the range of 1.3 to 4 times, and still more preferably in the range of 1.5 to 3 times, although it depends on the stretching temperature. When the stretch ratio is within the above range, the mechanical properties such as elongation, tensile strength, and fatigue resistance of the film can be significantly improved.
(use)
The resin film of the present invention can have its surface gloss reduced by a known method as needed. Examples of such a method include a method of adding an inorganic filler or crosslinkable polymer particles. Further, by embossing the obtained film, a surface roughness layer such as a prism shape, a pattern, an appearance, and a knurling can be formed, or gloss of the film surface can be reduced.
The resin film of the present invention can be used by laminating other films by a dry lamination method using an adhesive or an adhesive, a hot press method, or the like, or by forming a functional layer such as a hard coat layer, an antireflection layer, an antifouling layer, an antistatic layer, a printed decorative layer, a metal gloss layer, a surface roughness layer, or an achromatic layer on the surface or the back of the film, as required.
The resin film of the present invention can be used for various applications by utilizing properties such as heat resistance, transparency, and flexibility. For example, the solar cell back panel can be used for automobile internal and external decoration, computer internal and external decoration, portable internal and external decoration, solar cell internal and external decoration and solar cell back panels; influence fields such as camera, VTR, and imaging lens for projector, detector, filter, prism, fresnel lens, and lens cover, lens fields such as pickup lens for optical disk in CD player, DVD player, and MD player, optical recording fields for optical disk such as CD, DVD, and MD, information equipment fields such as film for organic EL, light guide plate for liquid crystal, diffuser plate, back plate, reflector plate, polarizer protective film, polarizing film transparent resin sheet, retardation film, light diffuser film, and prism sheet, and surface protective film, optical communication fields such as optical fiber, optical switch, and optical contactor, automobile head lamp, tail lamp lens, interior lens, instrument cover, and ceiling, medical equipment fields such as glasses, contact lens, lens for interior lens, and medical product required for sterilization treatment, road sign, bathroom equipment, floor material, and medical equipment field such as road sign, Light-transmitting road panels, lenses for wire glass, lighting windows, automobile valves, lighting lenses, lighting covers, building material construction fields such as building material calibration, electronic range cooking containers (tableware), covers for home electric appliances, toys, sun visors, stationery and the like. Further, the transfer foil sheet can be used as an alternative to a molded article using a transfer foil sheet.
The resin film of the present invention can be used by being laminated on a base material such as metal or plastic. Examples of the method of laminating the resin films include a wet lamination method, a dry lamination method, an extrusion lamination apparatus, and a hot melt lamination laminate, in which an adhesive is applied to a metal plate such as a steel plate, and then the metal plate is coated with the film and dried.
Examples of a method of laminating a film on a plastic member include insert molding or laminate injection press molding in which a film is placed in a mold and a resin is filled by injection molding, and molding in which a film is placed in a mold after preliminary molding and a resin is filled by injection molding.
The laminate of the resin film of the present invention can be used for coating substitution applications such as automobile interior materials and automobile exterior materials, window frames, bathroom equipment, wall papers, floor materials, lighting and dimming parts, sound-proof walls, parts for civil engineering and construction such as road markings, housings for household goods, furniture and electronic equipment, housings for OA equipment such as facsimiles, notebook computers and copying machines, front panels for liquid crystal screens at the ends of mobile phones, smart phones, dipoles and the like, optical parts such as lighting lenses, automobile headlights, optical lenses, optical fibers, optical disks, light guide plates for liquid crystals and the like, optical elements, parts for electric or electronic devices, essential medical supplies for sterilization treatment, toys or amusement supplies, fiber-reinforced resin composite materials and the like.
In particular, the resin film of the present invention is suitable as an optical film and can be used for various optical members from the viewpoint of excellent heat resistance and optical characteristics. For example, the present invention can be applied to known optical applications such as the periphery of liquid crystal display devices such as mobile phones, smart phones, and end-point liquid crystal panels of dipoles, lighting lenses, headlights of automobiles, optical lenses, optical fibers, optical disks, light guide plates for liquid crystals, diffusion plates, back plates, reflection sheets, polarizing films, transparent resin sheets, phase difference films, light diffusion films, prism sheets, surface protection films, optical isotropic films, polarizing plate protection films, and transparent conductive films, the periphery of organic EL devices, and the optical communication field.
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