WO2016185722A1

WO2016185722A1 - Resin composition and film

Info

Publication number: WO2016185722A1
Application number: PCT/JP2016/002447
Authority: WO
Inventors: 隆司大西; 進平間; 洋平今泉; 進悟 ▲徳▼原; 大祐松井
Original assignee: 株式会社日本触媒
Priority date: 2015-05-21
Filing date: 2016-05-19
Publication date: 2016-11-24
Also published as: JP6731913B2; JPWO2016185722A1

Abstract

A resin composition according to the present invention contains an acrylic resin (A) that has a positive intrinsic birefringence and a resin (B) that has a negative intrinsic birefringence and that has a constituent unit derived from N-substituted maleimide monomers. The constituent unit derived from N-substituted maleimide monomers is contained in this resin composition at between 1% and 10% by weight. The glass-transition temperature (Tg) of this resin composition is equal to or greater than 130 ºC. While the resin composition according to the present invention exhibits excellent optical transparency, which the acrylic resin possesses, and also achieves high heat resistance, to be more specific, a high Tg, deterioration of the mechanical characteristics thereof is suppressed, which makes it possible to more reliably ensure the characteristics expected of a resin composition in which multiple types of resins are mixed, and thus, the present invention provides a resin composition that can be used for various usages including optical films.

Description

Resin composition and film

The present invention relates to a resin composition and a film composed of the resin composition. More specifically, the present invention is for an optical film that can constitute an optical film such as a protective film, an antireflection film, a conductive film, and a polarizing film used in an image display device such as a liquid crystal display device and an organic electroluminescence display device. The present invention relates to a resin composition and the optical film.

An acrylic polymer typified by polymethyl methacrylate (PMMA) is widely used for optical applications because it is highly polymerizable and relatively easy to produce and has excellent optical transparency. For example, in addition to use as a bulk body such as an acrylic resin lens and substrate containing an acrylic polymer, use as a film (optical film) is also common. In recent years, optical films have been increasingly used in various image display devices such as liquid crystal display devices (LCD) and organic electroluminescence display devices (OLED).

As the application expands, acrylic resins are required to have heat resistance. For example, when an optical film is used for an image display device, the design of the device has heat resistance because it is necessary to dispose the optical film close to a heating element such as a power supply unit, a light emitting unit, and a circuit board. An optical film is required. Other examples of applications that require heat resistance include use in devices that are expected to be used in high-temperature environments such as devices mounted on vehicles, and substrates of transparent conductive films such as indium tin oxide (ITO) films For example, it is used for members that require processing at high temperatures.

One of the indices of heat resistance of polymers and resins is the glass transition temperature (Tg), and the higher the Tg, the higher the heat resistance. However, Tg of general acrylic polymers including PMMA and acrylic resins including the same is about 100 ° C. at the maximum. From a general acrylic resin, for example, it is not possible to obtain an optical film having heat resistance enough to withstand use in an image display device.

An optical film made of a heat-resistant acrylic polymer whose Tg is improved by arranging a ring structure in the main chain and an acrylic resin containing such a polymer is known. Further, it has been proposed to further improve the optical properties exhibited by the optical film, for example, to reduce birefringence, by blending with other resins to obtain a resin composition (see Patent Document 1). Patent Document 1 discloses an optical film composed of a resin composition including an acrylic polymer having a ring structure in the main chain and having positive intrinsic birefringence, and a styrene polymer having negative intrinsic birefringence. Is disclosed.

JP 2012-18315 A

In the heat-resistant acrylic polymer, the ring structure of the main chain improves its Tg. However, while the Tg increases as the content of the ring structure in the polymer increases, the mechanical properties of the polymer decrease, typically changing to a hard and brittle polymer. In addition, acrylic polymers are inherently harder and more brittle than other thermoplastic polymers. These points can be obtained by simply increasing the content of the ring structure of the main chain when it is required to further increase the Tg of the acrylic polymer, taking into account sufficient securing of its mechanical properties. That doesn't mean that. For example, the use of an acrylic polymer with a simple increase in the content of the ring structure of the main chain in an optical film may further increase the Tg of the film and improve the heat resistance. , Causing deterioration of mechanical properties such as flexibility and handling (handling property). Although the deterioration of the mechanical properties can be alleviated by stretching the film, it is of course necessary to secure the mechanical properties in the unstretched film state for the production of the stretched film. In addition, the decrease in mechanical properties reduces the stretchability of the unstretched film itself.

Next, when a resin containing an acrylic polymer having a cyclic structure in the main chain is blended with another resin to obtain a resin composition, the simple increase in the content of the cyclic structure in the acrylic polymer is the resin composition. Therefore, it may be difficult to obtain characteristics that are expected to be achieved originally. An example of specific characteristics is low birefringence. By reducing the birefringence of the resin composition, it is possible to reduce the retardation development property due to stretching. For example, a stretched optical film having a small in-plane retardation Re and a thickness direction retardation Rth can be obtained. However, the ring structure of the main chain in the acrylic polymer positively increases the intrinsic birefringence of the polymer and the resin containing the polymer. In order to lower the birefringence of such a resin composition containing an acrylic polymer, it is necessary to add a large amount of polymer and / or additive having negative intrinsic birefringence to the resin composition. Depending on the type of polymer and additive to be added, there are many that lower the Tg of the resin composition and lower the heat resistance, and by increasing the content of the ring structure, the high heat resistance that could be achieved once is more than one. By adding such a polymer and / or additive for suppressing the refractive property, the resin composition cannot be maintained. In other words, in a resin composition including an acrylic polymer having a ring structure in the main chain, it is difficult to achieve both high heat resistance and low birefringence.

Next, another problem may occur depending on the type of ring structure. Among the ring structures that an acrylic polymer can have in the main chain, such as a glutarimide structure, a glutaric anhydride structure, and a lactone ring structure, the polymer main chain is formed by polymerization of monomers that already have a ring structure. There is a ring structure that is not introduced, but is introduced into the main chain by the progress of an intramolecular cyclization reaction on the precursor polymer. In order to increase the content of such a ring structure, the content of the structural unit contributing to the cyclization reaction in the precursor polymer must be increased. However, in that case, not only an ideal intramolecular cyclization reaction but also a reaction tends to proceed between the main chains of the precursor polymer, or the above structural units remain unreacted in the polymer. . The reaction between the main chains and the remaining of the structural unit cause problems such as gelation and coloring of the acrylic polymer. That is, there is a limit to simply increasing the content of the main chain ring structure in the acrylic polymer.

These points are not considered at all in the conventional technology.

One of the objects of the present invention is to enjoy the excellent optical transparency of the acrylic resin and to suppress the deterioration of the mechanical properties while achieving high heat resistance, more specifically, high Tg. The present invention provides a resin composition that can be used for various applications including an optical film, which can ensure the expected characteristics more reliably because it is a resin composition in which a plurality of resins are blended.

The resin composition of the present invention comprises an acrylic resin (A) having a positive intrinsic birefringence, a resin (B) having a negative intrinsic birefringence and having a structural unit derived from an N-substituted maleimide monomer. ,including. The content of the structural unit derived from the N-substituted maleimide monomer in the resin composition of the present invention is 1% by weight or more and 10% by weight or less. The glass transition temperature (Tg) of the resin composition of the present invention is 130 ° C. or higher.

The film of the present invention consists of the resin composition of the present invention.

According to the present invention, while enjoying the excellent optical transparency of the acrylic resin and achieving high heat resistance, more specifically, high Tg, a decrease in mechanical properties is suppressed, and a plurality of Since it is a resin composition in which a resin is blended, it is possible to obtain a resin composition that can be used for various applications including an optical film, which can ensure the expected characteristics more reliably.

The first aspect of the present disclosure includes an acrylic resin (A) having positive intrinsic birefringence, and a resin (B) having a negative intrinsic birefringence and having a structural unit derived from an N-substituted maleimide monomer And a resin composition having a content of structural units derived from the N-substituted maleimide monomer of 1% by weight to 10% by weight and a glass transition temperature (Tg) of 130 ° C. or higher. To do.

The second aspect of the present disclosure provides a resin composition in which a difference in Tg between the acrylic resin (A) and the resin (B) is 20 ° C. or less in addition to the first aspect.

The third aspect of the present disclosure provides a resin composition in which the absolute value of the stress optical coefficient Cr is 1.0 × 10 ⁻¹⁰ Pa ⁻¹ or less in addition to the first or second aspect.

The fourth aspect of the present disclosure provides a resin composition in which the acrylic resin (A) has a ring structure in the main chain in addition to any of the first to third aspects.

According to a fifth aspect of the present disclosure, in addition to the fourth aspect, the ring structure is at least one selected from a lactone ring structure, a glutarimide structure, a glutaric anhydride structure, a maleic anhydride structure, and an N-substituted maleimide structure. A resin composition that is a seed is provided.

According to a sixth aspect of the present disclosure, in addition to the fourth aspect, the ring structure is a ring structure formed by an intramolecular cyclization reaction between two adjacent structural units in the precursor polymer, and the resin composition Provided is a resin composition having a ring structure content of 30% by weight or less.

According to a seventh aspect of the present disclosure, in addition to any one of the first to sixth aspects, a resin in which the content of a structural unit derived from an N-substituted maleimide monomer in the resin composition is 5% by weight or less A composition is provided.

The eighth aspect of the present disclosure provides a resin composition in which, in addition to any one of the first to seventh aspects, the resin (B) further includes a structural unit derived from an aromatic vinyl monomer.

According to a ninth aspect of the present disclosure, in addition to any one of the first to eighth aspects, a resin composition having an absolute value of a photoelastic coefficient of 1.0 × 10 ⁻¹² Pa ⁻¹ or less is provided.

The tenth aspect of the present disclosure provides a film comprising the resin composition according to any one of the first to ninth aspects.

The eleventh aspect of the present disclosure is a stretched film in addition to the tenth aspect, and has an in-plane retardation Re for light having a wavelength of 590 nm of 5 nm or less, and an absolute value of the thickness direction retardation Rth for the light A film having a thickness of 5 nm or less is provided.

A twelfth aspect of the present disclosure is a stretched film in addition to the tenth or eleventh aspect, and exhibits a folding endurance of 200 times or more in a folding endurance (MIT) test performed based on the provisions of JIS P8115. Provide film.

In this specification, “resin” is a broader concept than “polymer”. The resin may be composed of, for example, one or two or more polymers, and if necessary, materials other than the polymer, for example, additives such as ultraviolet absorbers, antioxidants, fillers, compatibilizing agents, A stabilizer and the like may be included.

[Resin composition (C)]
Resin composition (C) of the present invention is a resin having a positive intrinsic birefringence (A) and a negative intrinsic birefringence and a structural unit S derived from an N-substituted maleimide monomer (B). The content rate of the structural unit S in a resin composition (C) is 1 to 10 weight%, and Tg of a resin composition is 130 degreeC or more.

The structural unit S contained in the resin (B) corresponds to an N-substituted maleimide structure which is a kind of ring structure located in the main chain of the polymer contained in the resin. That is, the presence of the structural unit S improves the heat resistance of the resin composition (C) containing the resin (B) and the resin (B), and more specifically increases Tg. The structural unit S (N-substituted maleimide structure) is particularly effective in increasing the Tg of the polymer among the ring structures located in the main chain of the polymer. For this reason, as one feature, the resin composition (C) achieves a high heat resistance of Tg ≧ 130 ° C. due to a smaller content of the ring structure than in the past. And as another characteristic, the fall of the characteristic of a resin composition (C), for example, a mechanical characteristic, is suppressed by inclusion of a ring structure less than before in order to achieve high heat resistance.

Another feature different from this is that the resin (B) itself has a function of giving positive intrinsic birefringence to the polymer having the unit S, but the resin (B) itself has an intrinsic birefringence. It is that it is negative. That is, although it has negative intrinsic birefringence, the absolute value of the stress optical coefficient Cr indicated by the resin (B) itself is reduced by the presence of the structural unit S. In other words, the structural unit S improves the Tg of the resin composition (C) containing the resin (B) and the resin (B), and the stress optical coefficient Cr of the resin (B) having negative intrinsic birefringence. Has the effect of reducing the absolute value. This is because, for example, a resin composition in which a plurality of resins are blended is expected, and more specifically, the characteristics expected based on the combination with the resin (A) can be ensured more reliably. Means. In other words, the degree of freedom in controlling the characteristics of the resin composition (C) is improved. The properties are, for example, mechanical properties and optical properties, and more specific examples are low birefringence, low photoelastic coefficient, low haze, high mechanical properties when made into a film (eg flexibility), Low dimensional change rate and low wavelength dispersion of birefringence. The absolute value of the stress optical coefficient Cr is a numerical value corresponding to the magnitude of birefringence exhibited by the resin or resin composition when stress is applied in one direction to the resin or resin composition. The larger the absolute value, the higher the birefringence expression of the resin and the resin composition.

The low birefringence of the resin composition is achieved by canceling out intrinsic birefringence between a resin having positive intrinsic birefringence and a resin having negative intrinsic birefringence. If the absolute value of Cr in the resin (B) can be reduced, low birefringence as the resin composition (C) can be achieved while adopting a resin having a small Cr absolute value as the resin (A) combined therewith. This means that the low birefringence in the resin composition (C) is more reliably achieved, and the stability of the low birefringence when, for example, a resin molded body, typically a stretched film, is used. Improve. When the absolute value of Cr of the resin contained in the resin composition is high, the stretching condition of the resin composition (C) for expressing low birefringence becomes severe. Also, when the absolute value of Cr of the resin contained in the resin composition is high, there is an effect of canceling out the intrinsic birefringence between the resins due to long-term use of the resin molded body and application of heat to the resin molded body. This is because there is a possibility that the birefringence corresponding to the height of the absolute value is restored. In addition, when the resin (A) includes a ring structure as will be described later, as a more specific example, when the resin (A) includes a polymer having a ring structure in the main chain, a resin having a low ring structure content ( A) can be adopted. This contributes to the low photoelastic coefficient, low haze, high flexibility, small dimensional change rate, etc., as the resin composition (C). In addition, the positive and negative intrinsic birefringence cancel each other between the constituent units of the resin (B) and between the resins of the resin composition (C). It means that sex is achieved. And as a premise of these advantageous characteristics, high Tg of 130 degreeC or more is achieved in the resin composition (C).

Conventional effects obtained by mixing a resin having an improved Tg due to the inclusion of a ring structure with another resin to form a resin composition containing two or more resins are the optical properties and / or mechanical properties of the resin composition. On the other hand, the Tg was lowered by using a resin composition, while being limited to the adjustment of the target characteristics. On the other hand, in the resin composition (C), while ensuring a high Tg of 130 ° C. or higher, the deterioration of the mechanical properties is further suppressed, and the degree of freedom in controlling the optical properties and / or mechanical properties is improved. Can also be put into view. Acrylic resin originally has characteristics that are harder and more brittle than other thermoplastic resins, and even if it is judged from the fact that the ring structure located in the main chain of the polymer makes this characteristic stronger, the resin composition These effects achieved by the product (C) are very advantageous and significant.

Specific examples of resin (A) and resin (B) will be described.

[Acrylic resin having positive intrinsic birefringence (A)]
The resin (A) is, for example, a thermoplastic resin. Resin (A) may be an amorphous resin.

Resin (A) is an acrylic resin containing an acrylic polymer (D). The content of the acrylic polymer (D) in the resin (A) is, for example, 50% by weight or more, 80% by weight or more, 90% by weight or more, and further 95% by weight or more. Resin (A) may contain only an acrylic polymer (D) as a polymer, and may consist of an acrylic polymer (D).

The acrylic polymer (D) has, for example, positive intrinsic birefringence.

The resin (A) is derived from the acrylic polymer (D) contained in the resin, and has an effect of imparting excellent optical transparency to the resin composition (C) and a molded body (resin molded body) of the composition. Have.

The acrylic polymer has a constitutional unit derived from (meth) acrylic acid ester (hereinafter referred to as (meth) acrylic acid ester unit) as a proportion of all structural units of the polymer ((meth) acrylic acid ester in the polymer). A polymer having a unit content of 40 mol% or more, preferably 50 mol% or more, more preferably 60 mol% or more. However, when the polymer has a ring structure that is a derivative of a (meth) acrylate unit in the main chain, as a more specific example, a monomer having a ring structure that is a derivative of a (meth) acrylate unit When the ring structure is introduced into the main chain of the polymer by copolymerization with, or in the precursor polymer, by an intramolecular cyclization reaction between two adjacent structural units containing a (meth) acrylate unit When the polymer has the formed ring structure in the main chain, if the total of the content of (meth) acrylic acid ester units and the content of the ring structure is 50 mol% or more, the polymer is an acrylic polymer. It is a coalescence.

Examples of (meth) acrylic acid esters include methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, n-butyl (meth) acrylate, and t-butyl (meth) acrylate. , N-hexyl (meth) acrylate, cyclohexyl (meth) acrylate, benzyl (meth) acrylate, chloromethyl (meth) acrylate, 2-chloroethyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate , (Meth) acrylic acid 3-hydroxypropyl, (meth) acrylic acid 2,3,4,5,6-pentahydroxyhexyl, (meth) acrylic acid 2,3,4,5-tetrahydroxypentyl A structural unit derived from the body. The acrylic polymer (D) preferably has a methyl (meth) acrylate unit, and more preferably has a methyl methacrylate (MMA) unit. In these cases, the optical properties and thermal stability of the resin molding obtained by molding the resin composition (C) are further improved. The acrylic polymer (D) may have two or more (meth) acrylic acid ester units.

The acrylic polymer (D) can have a ring structure in the main chain. In this case, the above-described effect achieved by the resin composition (C) becomes more reliable. When the acrylic polymer (D) has a ring structure in the main chain, that is, when the resin (A) has the ring structure, the resin composition (C) is a resin having a ring structure together with the resin (B). Will contain at least two or more. The Tg of the resin composition (C) becomes a high value of 130 ° C. or more due to the presence of the ring structure. In this case, not only the resin (B) but also the resin (A) increases the Tg of the resin composition (C). Has an effect. For this reason, it is possible to further control the type of the ring structure in the resin (A) and the content of the ring structure in both resins (A) and (B) while maintaining Tg at 130 ° C. or higher. The degree of freedom in controlling other characteristics other than Tg and Tg is further increased. In addition, since both the resins (A) and (B) have a ring structure, the difference in Tg between the resin (A) and the resin (B) can be reduced. This means that the low birefringence in the resin composition (C) is more reliably achieved, and the stability of the low birefringence when, for example, a resin molded body, typically a stretched film, is used. Improve. When the difference in Tg between the resins contained in the resin composition is large, the state of both resins (for example, the stretched state) is unsatisfactory due to long-term use of the resin molded body or application of heat to the resin molded body. This is because it may change evenly. When the resin composition (C) is stretched to obtain a resin molded body, the smaller the difference in Tg between the two resins (A) and (B), the lower the degree of freedom in adjusting the stretching conditions, particularly the stretching temperature. Increase. This is because the stretched state of the resin changes greatly depending on the temperature difference between the stretching temperature and the Tg of the resin.

The ring structure that the acrylic polymer (D) may have in the main chain is, for example, at least one selected from a lactone ring structure, a glutarimide structure, a glutaric anhydride structure, a maleic anhydride structure, and an N-substituted maleimide structure. is there. These ring structures have a function of imparting positive intrinsic birefringence to the acrylic polymer (D) and the resin (A) containing the polymer (D).

The following formula (1) shows an N-substituted maleimide structure and a maleic anhydride structure. The structure shown in Formula (1) can also be a structural unit of the acrylic polymer (D) having the structure in the main chain.

In the formula (1), R ¹ and R ² are each independently a hydrogen atom or a methyl group, and X ¹ is an oxygen atom or a nitrogen atom. When X ¹ is an oxygen atom, R ³ does not exist, and when X ¹ is a nitrogen atom, R ³ is a hydrogen atom, a linear or branched alkyl group having 1 to 6 carbon atoms, a cyclopentyl group, a cyclohexyl group, a phenyl group Or a benzyl group. In the phenyl group and benzyl group, one or more hydrogen atoms of the benzene ring may be substituted. When X ¹ is a nitrogen atom, R ³ is preferably a methyl group, a cyclohexyl group, a phenyl group, or a benzyl group, and more preferably a methyl group, a cyclohexyl group, or a phenyl group.

When X ¹ is a nitrogen atom, the ring structure represented by the formula (1) is an N-substituted maleimide structure. The acrylic polymer having an N-substituted maleimide structure in the main chain can be formed, for example, by copolymerizing a monomer group containing N-substituted maleimide and (meth) acrylic acid ester as monomers.

N-substituted maleimide structures are, for example, cyclohexylmaleimide, methylmaleimide, phenylmaleimide, and benzylmaleimide.

When X ¹ is an oxygen atom, the ring structure represented by the formula (1) is a maleic anhydride structure. The acrylic polymer having a maleic anhydride structure in the main chain can be formed, for example, by copolymerizing a monomer group containing maleic anhydride and (meth) acrylic acid ester as monomers.

The following formula (2) shows a glutarimide structure and a glutaric anhydride structure. The structure shown in Formula (2) is a ring structure formed by an intramolecular cyclization reaction of the precursor polymer. The structure in which the methylene group is bonded to any one of the main chain carbon atoms (the carbon atom to which R ⁴ or R ⁵ is bonded) in the structure represented by the formula (2) is an acrylic polymer (D). It becomes a structural unit.

R ⁴ and R ⁵ in formula (2) are each independently a hydrogen atom or a methyl group, and X ² is an oxygen atom or a nitrogen atom. When X ² is an oxygen atom, R ⁶ is not present, and when X ² is a nitrogen atom, R ⁶ is a hydrogen atom, a linear or branched alkyl group having 1 to 6 carbon atoms, a cyclopentyl group, a cyclohexyl group, a phenyl group Or a benzyl group. When X ² is a nitrogen atom, R ⁶ is preferably a methyl group, a cyclohexyl group, a phenyl group, or a benzyl group, and more preferably a methyl group, a cyclohexyl group, or a phenyl group.

When X ² is a nitrogen atom, the ring structure represented by the formula (2) is a glutarimide structure. An acrylic polymer having a glutarimide structure in the main chain is formed, for example, by intramolecular cyclization (imidation) of a precursor polymer that is an uncyclized acrylic polymer such as PMMA with an imidizing agent such as methylamine. it can. At this time, a glutarimide structure is formed by a cyclization reaction between two adjacent structural units in the precursor polymer, more specifically, between two adjacent (meth) acrylate units.

When X ² is an oxygen atom, the ring structure represented by the formula (2) is a glutaric anhydride structure. The acrylic polymer having a glutaric anhydride structure in the main chain is obtained by, for example, subjecting a precursor polymer, which is a copolymer of (meth) acrylic acid ester and (meth) acrylic acid, to dealcoholization cyclocondensation in the molecule. Can be formed. At this time, a glutaric anhydride structure is formed by cyclization reaction between two adjacent structural units in the precursor polymer, more specifically, between adjacent (meth) acrylic acid ester units and (meth) acrylic acid units. Is formed.

An example of a lactone ring structure is shown in the following formula (3). The structure shown in Formula (3) is a ring structure formed by an intramolecular cyclization reaction of the precursor polymer. Of the carbon atoms in the main chain in the structure represented by the formula (3), a structure in which a methylene group is bonded to a carbon atom to which R ⁹ is bonded is a constituent unit of the acrylic polymer (D).

In the formula (3), R ⁷ , R ⁸ and R ⁹ are each independently a hydrogen atom or an organic residue having 1 to 20 carbon atoms. The organic residue may contain an oxygen atom.

The organic residue is, for example, an alkyl group having 1 to 20 carbon atoms, such as a methyl group, an ethyl group, or a propyl group; an unsaturated aliphatic carbonization having 1 to 20 carbon atoms, such as an ethenyl group or a propenyl group. A hydrogen group; an aromatic hydrocarbon group having 1 to 20 carbon atoms, such as a phenyl group or a naphthyl group; one of hydrogen atoms in the alkyl group, the unsaturated aliphatic hydrocarbon group and the aromatic hydrocarbon group; One or more groups are substituted with at least one group selected from a hydroxyl group, a carboxyl group, an ether group and an ester group.

The acrylic polymer having a lactone ring structure represented by the formula (3) in the main chain includes, for example, a (meth) acrylic acid ester and a (meth) acrylic acid ester having a hydroxyl group and / or a carboxyl group in the molecule. After copolymerization of the monomer group, it can be formed by proceeding an intramolecular dealcoholization cyclocondensation reaction between constituent units derived from the respective monomers with respect to the obtained precursor polymer as a copolymer. . The (meth) acrylic acid ester is, for example, methyl methacrylate (MMA), and the (meth) acrylic acid ester having a hydroxyl group and / or a carboxyl group in the molecule is, for example, methyl 2- (hydroxymethyl) acrylate (MHMA). ). In this case, the adjacent MMA unit and MHMA unit in the obtained copolymer are subjected to dealcoholization cyclocondensation so that R ⁷ is H and R ⁸ and R ⁹ are CH _3. An acryl polymer having the lactone ring structure shown in FIG.

The lactone ring structure is not limited to the structure shown in Formula (3), and may be, for example, a 5-membered lactone ring structure instead of the 6-membered ring shown in Formula (3).

Among the ring structures described above, a glutarimide structure, a glutaric anhydride structure, and a lactone ring structure are ring structures formed by an intramolecular cyclization reaction between two adjacent structural units in the precursor polymer. Such a ring structure becomes a structural unit of the acrylic polymer (D) in a state where a methylene group is bonded to a carbon atom of the main chain of the ring structure. Therefore, when the acrylic polymer (D) has such a ring structure in the main chain, the steric hindrance due to the ring structure is alleviated by the methylene group, and the mechanical properties of the resin (A) and the resin composition (C) are reduced. The decrease can be further suppressed. In this case, the direction of the main chain of the polymer and the polarization direction of the conjugated electrons of the ring structure are almost parallel, and the action of the ring structure that gives positive intrinsic birefringence to the polymer becomes stronger. From the viewpoint of securing optical properties, the content of the ring structure in the polymer (D) and the resin (A) can be reduced. This also contributes to the reduction in mechanical properties of the resin (A) and the resin composition (C).

Further, when the acrylic polymer (D) has such a ring structure, the polymer (D) may have a structural unit remaining from the precursor polymer without participating in the intramolecular cyclization reaction. For example, the polymer (D) can have a (meth) acrylic acid ester unit having an unreacted hydroxyl group and / or carboxyl group.

From the viewpoint of further improving the compatibility of the resin composition (C) with the resin (B), and compared with the ring structure formed by the intramolecular cyclization reaction of the precursor polymer, the resin composition (C) From the viewpoint of further improving heat resistance, typically Tg, the ring structure of the acrylic polymer (D) in the main chain may be an N-substituted maleimide structure.

When the acrylic polymer (D) has a ring structure in the main chain, the content of the ring structure in the polymer (D) is, for example, 2% by weight or more and 50% by weight or less. Within this range, while making the intrinsic birefringence of the resin (A) positive, the heat resistance of the resin composition (C) can be improved in a well-balanced manner, and the deterioration of the mechanical properties of the resin composition (C) can be further suppressed. The lower limit of the content of the ring structure in the acrylic polymer (D) is more preferable in the order of 3% by weight, 4% by weight or more, 5% by weight or more, and 6% by weight or more. The upper limit of the content of the ring structure in the acrylic polymer (D) is more preferable in the order of 45% by weight or less, 40% by weight or less, and 35% by weight or less. The same applies to the content of the ring structure in the resin (A).

The weight average molecular weight Mw of the acrylic polymer (D) is, for example, 10,000 to 500,000, preferably 50,000 to 300,000.

The acrylic polymer (D) may further have a structural unit other than the (meth) acrylic acid ester unit and the ring structure described above. The structural unit includes, for example, structural units derived from aromatic vinyl monomers such as styrene, vinyltoluene, α-methylstyrene, α-hydroxymethylstyrene, and α-hydroxyethylstyrene; and acrylonitrile, methacrylonitrile, For each monomer such as ril alcohol, allyl alcohol, ethylene, propylene, 4-methyl-1-pentene, vinyl acetate, 2-hydroxymethyl-1-butene, methyl vinyl ketone, N-vinyl pyrrolidone, N-vinyl carbazole It is a derived structural unit. The acrylic polymer (D) can have two or more of these structural units.

When the acrylic polymer (D) further has a structural unit derived from an aromatic vinyl monomer, the content of the structural unit in the acrylic polymer (D) is preferably 5% by weight or less, more preferably 4 % By weight or less.

The formation method of the acrylic polymer (D) is not limited, and can be formed by a general polymerization method such as cast polymerization, bulk polymerization, suspension polymerization, solution polymerization, emulsion polymerization, living radical polymerization, and anionic polymerization. When the resin composition (C) is used for optical applications, cast polymerization that does not use a suspending agent and an emulsifier in order to avoid as much as possible the entry of minute foreign matters into the acrylic polymer (D) and the resin composition (C). Or formation of the acrylic polymer (D) by solution polymerization is preferable.

The upper limit of the stress optical coefficient Cr of the resin (A) is, for example, 6.0 × 10 ⁻¹⁰ Pa ⁻¹ or less, 5.0 × 10 ⁻¹⁰ Pa ⁻¹ or less, 4.5 × 10 ⁻¹⁰ Pa ⁻¹ or less. It is more preferable in this order. The lower limit of the stress optical coefficient Cr of the resin (A) is, for example, 0.1 × 10 ⁻¹⁰ Pa ⁻¹ or more, 0.5 × 10 ⁻¹⁰ Pa ⁻¹ or more, 1.0 × 10 ⁻¹⁰ Pa ⁻¹ or more. It is more preferable in this order.

The method for forming the resin (A) is not limited, and the acrylic polymer (D) may be used as it is, and if necessary, the acrylic polymer (D), other polymers, other resins and / or Or it can form by mixing an additive with a well-known method. For mixing, for example, an extruder can be used. The resin (A) discharged from the extruder may be pelletized with a pelletizer as it is. Other resins and additives will be described later in the description of the resin composition (C).

[Resin (B) having a negative intrinsic birefringence and having a structural unit derived from an N-substituted maleimide monomer]
Resin (B) is, for example, a thermoplastic resin. Resin (B) may be an amorphous resin.

Resin (B) has negative intrinsic birefringence and an N-substituted maleimide structure that is a structural unit derived from an N-substituted maleimide monomer. The resin (B) includes, for example, a polymer (E) having an N-substituted maleimide structure in the main chain. The polymer (E) has a negative intrinsic birefringence.

The specific N-substituted maleimide structure is the same as the above-described N-substituted maleimide structure that the acrylic polymer (D) may have in the main chain.

As described above, the N-substituted maleimide structure is more polymerized than the main chain ring structure introduced by the intramolecular cyclization reaction to the precursor polymer, such as glutarimide structure, glutaric anhydride structure, and lactone structure. On the other hand, the effect of making the intrinsic birefringence positive is low. For this reason, even if the introduction amount of the N-substituted maleimide structure into the polymer (E) and the resin (B) is increased, the resin (B) tends to maintain negative intrinsic birefringence. In a polymer having an N-substituted maleimide structure in the main chain, a methylene group does not necessarily exist adjacent to the N-substituted maleimide structure. Therefore, due to the steric hindrance of the ring structure, the N-substituted maleimide structure has a high effect of improving the heat resistance of the polymer, typically Tg.

The content of the N-substituted maleimide structure in the polymer (E) which is a maleimide polymer is, for example, 5% by weight or more and 50% by weight or less. When the content of the N-substituted maleimide structure in the polymer (E) is excessively small, the effect of improving the heat resistance of the resin (B) and the resin composition (C) cannot be sufficiently obtained. On the other hand, if the content of the N-substituted maleimide structure in the polymer (E) becomes excessively large, the resin (B) becomes hard and brittle, and the effect of suppressing the deterioration of the mechanical properties of the resin composition (C) is obtained. It becomes difficult. The lower limit of the content of the N-substituted maleimide structure in the polymer (E) is more preferably in the order of 10% by weight or more, 15% by weight or more, 20% by weight or more, and 25% by weight or more. The upper limit of the content of the N-substituted maleimide structure in the polymer (E) is more preferably 45% by weight or less, 40% by weight or less, and 35% by weight or less.

The polymer (E) is a structural unit derived from an aromatic vinyl monomer (hereinafter referred to as an aromatic vinyl monomer) in order to cause the polymer (E) and the resin (B) to exhibit negative intrinsic birefringence. Unit) as a constituent unit. The aromatic vinyl monomer is not particularly limited, and examples thereof include styrene, vinyl toluene, α-methyl styrene, α-hydroxymethyl styrene, α-hydroxyethyl styrene, and chlorostyrene.

The lower limit of the content of the aromatic vinyl monomer unit in the polymer (E) is, for example, 10% by weight or more, preferably 30% by weight or more, more preferably 50% by weight or more. On the other hand, the upper limit of the content is, for example, 95% by weight or less, preferably 90% by weight or less, and more preferably 85% by weight or less. From the viewpoint of minimizing the stress optical coefficient Cr of the polymer (E) and the resin (B), the upper limit of the content of the aromatic vinyl monomer unit in the polymer (E) is 80% by weight or less, 70% by weight. % Or less and 60% by weight or less are more preferable in this order.

The weight average molecular weight Mw of the polymer (E) is, for example, 10,000 to 500,000, preferably 50,000 to 300,000.

The polymer (E) may further have a structural unit other than the N-substituted maleimide structure and the aromatic vinyl monomer unit. The structural unit includes, for example, methyl (meth) acrylate, ethyl (meth) acrylate, acrylonitrile, methacrylonitrile, methallyl alcohol, allyl alcohol, ethylene, propylene, 4-methyl-1-pentene, vinyl acetate, A structural unit derived from each monomer of -hydroxymethyl-1-butene, methyl vinyl ketone, N-vinyl pyrrolidone and N-vinyl carbazole. The polymer (E) can have two or more of these structural units.

When the polymer (E) has a structural unit derived from an acrylonitrile monomer, the lower limit of the content of the structural unit in the polymer (E) is, for example, 3% by weight or more, preferably 5% by weight or more. Preferably it is 10 weight% or more. On the other hand, the upper limit of the content is, for example, 40% by weight or less, preferably 30% by weight or less, more preferably 20% by weight or less.

The upper limit of the stress optical coefficient Cr of the resin (B) is, for example, −10.0 × 10 ⁻¹⁰ Pa ⁻¹ or less, −15.0 × 10 ⁻¹⁰ Pa ⁻¹ or less, or −20.0 × 10 ⁻¹⁰ Pa. ^-1 or less is more preferable. The lower limit of the stress optical coefficient Cr of the resin (B) is, for example, −45.0 × 10 ⁻¹⁰ Pa ⁻¹ or more, −40.0 × 10 ⁻¹⁰ Pa ⁻¹ or more, −35.0 × 10 ⁻¹⁰ Pa. ^-1 or more is more preferable.

The formation method of the polymer (E) is not limited, and can be formed by a general polymerization method such as cast polymerization, bulk polymerization, suspension polymerization, solution polymerization, emulsion polymerization, living radical polymerization, and anionic polymerization. When the resin composition (C) is used for optical applications, in order to avoid contamination of the polymer (E) and the resin composition (C) with fine foreign substances as much as possible, cast polymerization without using a suspending agent and an emulsifier or Formation of polymer (E) by solution polymerization is preferred.

The method for forming the resin (B) is not limited, and the polymer (E) may be used as it is, and if necessary, the polymer (E), another polymer, another resin and / or addition It can be formed by mixing the agent with a known method. For mixing, for example, an extruder can be used. The resin (B) discharged from the extruder may be pelletized with a pelletizer as it is. Other resins and additives will be described later in the description of the resin composition (C).

[Resin composition (C)]
The resin composition (C) will be further described.

Resin composition (C) has a Tg of 130 ° C. or higher. Although the upper limit of Tg of a resin composition (C) is not specifically limited, For example, it is 200 degreeC and the moldability of a resin composition (C) becomes high in the range of 130 to 200 degreeC. The heat resistance of the resin composition (C) having a Tg of 130 ° C. or higher is high. For example, a film composed of the resin composition (C) can be easily arranged in the vicinity of a heat generating part such as a light source in an image display device. The molded article of the resin composition (C) can be used for a device that is assumed to be used in a high temperature environment such as a device mounted on a vehicle; or a substrate of a transparent conductive film or the like needs to be processed at a high temperature. Advantageous effects such as being able to use the resin composition (C) for the member are achieved.

In the resin composition (C), the resin (A) and the resin (B) are in a mutually compatible state. For this reason, a resin composition (C) can be used for an optical use. It can be judged that the resins contained in the resin composition are compatible with each other because the Tg of the resin composition measured in a temperature range of room temperature or higher is only one point. In other words, when the resins are not compatible with each other, a plurality of Tg values corresponding to the respective resins are measured in a temperature range of normal temperature or higher.

The content of the N-substituted maleimide structure in the resin composition (C) is 1% by weight or more and 10% by weight or less. When the said content rate is less than 1 weight%, the high heat resistance of a resin composition is not achieved. On the other hand, if the content exceeds 10% by weight, the mechanical properties of the resin composition are greatly reduced, or it is difficult to ensure the expected properties because the resin composition is a blend of a plurality of resins. The content of the N-substituted maleimide structure in the resin composition (C) is preferably 2% by weight to 8% by weight, more preferably 3% by weight to 6% by weight. The upper limit of the content of the N-substituted maleimide structure in the resin composition (C) can be 5% by weight or less. When the resin (A) contains an N-substituted maleimide structure, as a more specific example, when the acrylic polymer (D) contained in the resin (A) has an N-substituted maleimide structure in the main chain, the resin The N-substituted maleimide structure of the composition (C) is derived from both the resin (A) and the resin (B).

When the resin (A) contains a ring structure other than the N-substituted maleimide structure, as a more specific example, the acrylic polymer (D) contained in the resin (A) mainly has a ring structure other than the N-substituted maleimide structure. When it is present in the chain, the resin composition (C) contains the ring structure in addition to the N-substituted maleimide structure. In this case, the ring structure contained in the resin composition (C) is not collected in either one of the resin (A) and the resin (B), but the resin (A) and the resin (B) Moreover, it is also in a state of being sorted according to the type. In this case, the effect of the present invention described above becomes more remarkable. More specifically, while achieving high heat resistance, the deterioration of mechanical properties is further suppressed, and the expected properties can be ensured more reliably because of the resin composition.

When the resin composition (C) includes a ring structure other than the N-substituted maleimide structure, the lower limit of the content of all ring structures including the N-substituted maleimide structure in the resin composition (C) is, for example, 10% by weight. Yes, 15% by weight or more, 20% by weight or more, and 25% by weight or more in order. On the other hand, the upper limit of the content is more preferably, for example, in the order of 40% by weight or less, 35% by weight or less, and 30% by weight or less in order to more reliably suppress the deterioration of the mechanical properties of the resin composition.

In the case where the resin (A) includes a ring structure other than the N-substituted maleimide structure, the ring structure is a ring structure formed by an intramolecular cyclization reaction between two adjacent structural units in the precursor polymer. In some cases, the content of the ring structure in the resin composition (C) may be 30% by weight or less. For example, when the Tg of the resin composition is made to be 130 ° C. or higher only with such a ring structure, the content of the ring structure in the resin composition needs to be larger, for example, 35% by weight or more. However, although such a resin composition can achieve a high Tg, the mechanical properties are strongly reduced. On the other hand, in the resin composition (C) in which the resin (A) contains a ring structure other than the N-substituted maleimide structure, the resin composition (A) contains an N-substituted maleimide structure that has a strong effect of improving the heat resistance of the resin composition. ) And (B), the content can be reduced to 30% by weight or less, and the deterioration of the mechanical properties of the resin composition can be further suppressed while achieving high heat resistance.

When the resin composition (C) further contains a ring structure other than the N-substituted maleimide structure, the content of the ring structure other than the N-substituted maleimide structure with respect to the content T1 of the N-substituted maleimide structure in the resin composition (C) The lower limit of the ratio T2 / T1 of T2 is, for example, 1 or more, preferably 3 or more, more preferably 5 or more, and the upper limit of the ratio is, for example, 20 or less, preferably 15 or less, more preferably 10 or less. The ring structure other than the N-substituted maleimide structure is, for example, a ring structure formed by an intramolecular cyclization reaction between two adjacent structural units in the precursor polymer. Specific examples include a glutarimide structure, an anhydrous structure, and the like. It is at least one selected from a glutaric acid structure and a lactone ring structure, and a more specific example is a lactone ring structure.

The content of the (meth) acrylic acid ester unit in the resin composition (C) is preferably 50% by weight or more and 70% by weight or less. In this range, when the content of the ring structure in the resin composition (C) and the resin (B) have an aromatic vinyl monomer unit, the content of the unit is further set to a more appropriate range. Therefore, the effect of the present invention can be obtained more reliably.

When the resin (B) has an aromatic vinyl monomer unit, the upper limit of the content of the unit in the resin composition (C) is preferably 15% by weight or less. When the content of the unit in the resin composition (C) becomes excessively large, for example, the birefringence of the resin composition (C) becomes negatively large and a small birefringence cannot be achieved, that is, the resin composition ( The degree of freedom in controlling the characteristics in C) decreases.

The mixing ratio (weight ratio) of the resin (A) and the resin (B) in the resin composition (C) is such that the content of the N-substituted maleimide structure in the resin composition (C) is 1 wt% or more and 10 wt% or less. There is no particular limitation as long as compatibility between the resin (A) and the resin (B) is ensured and the effect of the present invention is obtained. The mixing ratio varies depending on the specific structures of the resins (A) and (B), but as an example, the resin (A): resin (B) = 99: 1 to 1:99, preferably 95: 5. To 5:95, more preferably 90:10 to 10:90. In order to obtain the effect of the present invention more reliably, the mixing ratio is preferably resin (A): resin (B) = 99: 1 to 50:50, more preferably 96: 4 to 60:40, and still more preferably. Is 93: 7 to 70:30.

Resin composition (C) may be an acrylic resin composition.

The difference in Tg between the resin (A) and the resin (B) is preferably 0 to 20 ° C, more preferably 0 to 18 ° C, and further preferably 0 to 17 ° C. In this case, while achieving low birefringence in the resin composition (C) is more reliable, for example, the low birefringence of the resin molded body composed of the resin composition, typically a stretched film, is more preferable. Improve stability. Although the resin (A) and the resin (B) are compatible in the resin composition (C), if the difference in Tg between the two increases, depending on the stretching temperature and / or the use temperature of the resin molding, This is because the orientation of the molecular chains is likely to be affected differently by changes in the stretching temperature and / or the use temperature.

Resin composition (C) may contain a polymer and / or a resin other than the above-described polymer and resin. These polymers and / or resins may be derived from the resin (A) (included in the resin (A)) or from the resin (B), or the resins (A) and (B). And may be contained in the resin composition (C) independently. That is, the origin of these polymers and / or resins in the resin composition (C) does not matter. However, the compatibility of the resin composition (C) as a whole needs to be satisfied. Specific examples of the resin and polymer include polyolefins such as polyethylene, polypropylene, ethylene-propylene copolymer, poly (4-methyl-1-pentene), and halogen-containing heavy resins such as polyvinyl chloride and polychlorinated vinyl. Polymer; Acrylic polymer such as polymethyl methacrylate; Polyester such as polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate; Polyamide such as nylon 6, nylon 66, nylon 610; Polyacetal; Polycarbonate; Polyphenylene oxide; Polyphenylene sulfide; Polyethersulfone; Polyethersulfone; Polyoxypentylene; Polyamideimide; and resins containing these polymers. The resin composition can contain two or more of these polymers and / or resins. The total content of these polymers and resins in the resin composition (C) is, for example, 15% by weight or less, and more preferably in the order of 12% by weight or less and 10% by weight or less.

Unless the optical transparency of the resin composition is significantly affected, for example, as long as 2% or less is achieved in terms of haze per 100 μm thickness, the resin composition (C) is a resin (A) and / or A polymer and / or resin that is incompatible with the resin (B) can be included. An example of these polymers and resins is an elastomer (G) such as a rubbery polymer. The resin composition can contain 2 or more types of elastomers (G).

When the resin composition (C) contains the elastomer (G), the mechanical properties of the resin composition (C) and the resin molded body composed of the composition, for example, flexibility, and more specific bending resistance Improve.

The configuration and shape of the elastomer (G) are not limited, and examples thereof include organic fine particles having a crosslinked structure, and a block copolymer having a hard part (g1) and a soft part (g2).

Organic fine particles having a crosslinked structure can be formed, for example, by polymerization of a monomer group containing a polyfunctional compound having two or more nonconjugated double bonds per molecule. The organic fine particles exhibit crosslinking elasticity based on a core portion having a crosslinked structure. The organic fine particles preferably have a core-shell structure. In this case, the dispersibility of the organic fine particles in the resin composition (C) is improved. In a preferable embodiment of the organic fine particles having a core / shell structure, a structure derived from a polyfunctional compound is constructed only in the central portion (core), and a resin (in the shell) surrounding the central portion (core) is formed. A structure having high compatibility with the acrylic resin (A) contained in the composition (C) is constructed. By the construction of this structure, the dispersibility of the organic fine particles in the resin composition (C) is further improved. The improvement in dispersibility makes the dispersed state of the organic fine particles in the resin composition (C) more uniform. Thereby, the flexibility (for example, bending resistance) of the film comprised from the resin composition (C) can be further improved, for example. Moreover, since aggregation of the organic fine particles in the resin composition (C) can be suppressed, the composition can be filtered while preventing the filter from being clogged when forming the resin composition (C), and foreign matter contained therein The resin composition (C) with a small amount of can be provided. Commercially available organic fine particles include, for example, Kane Ace M210, an acrylic modifier manufactured by Kaneka (rubber particles having a multilayer structure; a core is a multilayer acrylic rubber; a shell is an acrylic polymer mainly composed of methyl methacrylate; About 220 nm).

The configuration of the block copolymer is not limited. For example, the molecular chain may be linear, branched, or radial. A preferred form of the block copolymer is at least a polymer block mainly composed of methacrylic acid ester units as the hard portion (g1), and a polymer block mainly composed of acrylate ester units as the soft portion (g2). Have one. Another preferred embodiment is a binary triblock copolymer represented by (g1)-(g2)-(g1) or (g2)-(g1)-(g2). In a more preferred form of the block copolymer, the hard part (g1) has a composition that achieves high compatibility with the resin (A) and / or the resin (B), and in a more preferred form, the hard part ( g1) has the same composition as resin (A) or resin (B). Thereby, the flexibility (for example, bending resistance) of the film comprised from the resin composition (C) can be further improved, for example. Moreover, since the aggregation of the block copolymer in the resin composition (C) can be suppressed, the composition can be filtered while preventing clogging of the filter when the resin composition (C) is formed. A resin composition (C) with a reduced amount of foreign matter can be provided. Commercially available block copolymers are, for example, Kuraray, Clarity LA4285 and LA2250.

When the resin composition (C) contains the elastomer (G), the content of the elastomer (G) in the resin composition (C) is limited unless it greatly affects the optical transparency of the resin composition (C). For example, it is 1% by weight or more and 15% by weight or less. In this range, the effect of improving the mechanical properties of the film, such as flexibility, is ensured, and the decrease in Tg of the resin composition (C) is suppressed. The lower limit of the content is more preferably in the order of 2% by weight or more, 3% by weight or more, 4% by weight or more, and 5% by weight or more. The upper limit of the content is preferably 10% by weight or less. In addition, since Tg of elastomer (G) is normally less than normal temperature, Tg of elastomer is not measured in the measurement of Tg of the resin composition in the temperature range above normal temperature. This means that the compatibility between the resins (A) and (B) can be determined by the measurement. However, the resin composition in the temperature region where the Tg of the hard part (g1) when the elastomer (G) is a block copolymer and the Tg of the shell when the elastomer (G) has a core-shell structure is a room temperature or higher. It may be measured in the measurement of the Tg of an object. At this time, since the Tg can be easily distinguished from the Tg of the resins (A) and (B), the compatibility between the resins (A) and (B) can be determined by the measurement.

As long as the effect of the present invention is obtained, the resin composition (C) can contain materials other than the polymer and the resin, for example, additives. Additives include, for example, antioxidants, light stabilizers, weather stabilizers, heat stabilizers and other stabilizers; phase difference adjusting agents such as phase difference increasing agents, phase difference reducing agents, phase difference stabilizers; glass fibers, Reinforcing materials such as carbon fibers; ultraviolet absorbers; near infrared absorbers; flame retardants such as tris (dibromopropyl) phosphate, triallyl phosphate, antimony oxide; antistatic agents including anionic, cationic or nonionic surfactants Agents; colorants such as inorganic pigments, organic pigments, dyes; organic fillers, inorganic fillers, resin modifiers, plasticizers, lubricants. The total content of additives in the resin composition (C) is preferably less than 7% by weight, more preferably 5% by weight or less, still more preferably 2% by weight or less, and particularly preferably 0.5% by weight or less. is there.

The total content of the resin (A) and the resin (B) in the resin composition (C) is preferably 80% by weight or more, and more preferably 90% by weight or more. Resin composition (C) may consist of resin (A) and resin (B).

The composition of the resin composition (C), for example, the content of the resin (A) and the resin (B) in the resin composition (C), the composition of the resin (A) and the resin (B), and the resin (A) and the resin ( In addition to B), the composition and content of the polymer and resin contained in the resin composition (C) can be determined by known methods such as ¹ H-nuclear magnetic resonance (NMR) measurement, infrared spectroscopy (IR), etc. It can be evaluated by various methods. When the resin composition (C) contains a material that is incompatible with the resin (A) and the resin (B), for example, the elastomer (G), the evaluation is performed on the resin composition from which these materials have been removed. It is preferable to do.

In the resin composition (C), since it is a resin composition in which a plurality of resins are blended, the expected characteristics can be more reliably ensured. An example of a property is low birefringence. The absolute value of the stress optical coefficient Cr of the resin composition (C) can be, for example, 1.0 × 10 ⁻¹⁰ Pa ⁻¹ or less. Depending on the composition of the resin composition (C), 0.9 × 10 ^{− 10} Pa ⁻¹ or less, 0.8 × 10 ⁻¹⁰ Pa ⁻¹ or less, 0.7 × 10 ⁻¹⁰ Pa ⁻¹ or less, 0.6 × 10 ⁻¹⁰ Pa ⁻¹ or less, 0.5 × 10 ⁻¹⁰ Pa ⁻¹ or less, 0.4 × 10 ⁻¹⁰ Pa ⁻¹ or less, and further 0.3 × 10 ⁻¹⁰ Pa ⁻¹ or less. According to the resin composition (C) that exhibits low birefringence, for example, a film that exhibits low birefringence, that is, a small retardation value is obtained. Such a film can be used for an image display device as a polarizer protective film, for example.

In the resin composition (C), not only the resin composition (C) but also each of the resin (A) and the resin (B) may take an absolute value range of these stress optical coefficients Cr.

Another example of a characteristic is a low photoelastic coefficient, more precisely the absolute value of the low photoelastic coefficient. A resin composition having a small absolute value of the photoelastic coefficient and a resin molded body composed of such a resin composition have a small change in birefringence due to the application of external force. According to the resin composition (C) showing a low photoelastic coefficient, for example, a film showing a low photoelastic coefficient can be obtained. Such a film can be used for an image display device, for example, as a film capable of suppressing light leakage, particularly light leakage in a high temperature and high humidity environment. The absolute value of the photoelastic coefficient of the resin composition can be, for example, 1.0 × 10 ⁻¹² Pa ⁻¹ or less, and depending on the composition of the resin composition (C), 0.9 × 10 ⁻¹² Pa ^−1. Hereinafter, 0.8 × 10 ⁻¹² Pa ⁻¹ or less, 0.7 × 10 ⁻¹² Pa ⁻¹ or less, 0.6 × 10 ⁻¹² Pa ⁻¹ or less, and further 0.5 × 10 ⁻¹² Pa ^−1. It can be:

Another example of characteristics is low haze. The resin composition (C) having a small haze has high optical transparency when used as a film, for example, and such a film can be suitably used for optical applications. The haze of the resin composition (C) can be, for example, 2% or less as a value in the thickness direction when a film having a thickness of 100 μm is formed. Depending on the composition of the resin composition (C), 1. It can be 5% or less, 1% or less, and even 0.5% or less.

Another example of characteristics is suppression of deterioration of mechanical characteristics, in other words, retention of high mechanical characteristics. The resin composition (C) can have, for example, high flexibility and low dimensional change rate when formed into a film. The flexibility can be evaluated by, for example, a film folding resistance test (MIT test). Details will be described later in the description of the film composed of the resin composition (C).

The formation method of the resin composition (C) is not particularly limited. The resin composition (C) is, for example, a resin (A) and (B) and, if necessary, a polymer and / or resin other than the resins (A) and (B), or additives, It can be formed by mixing by the method. Materials other than the resins (A) and (B) may be mixed together with the resins (A) and (B), or may be mixed in advance separately from the resins (A) and (B). You may mix further in addition to the mixture of A) and (B). Mixing can be carried out, for example, by pre-blending with a mixer such as an omni mixer and then kneading the resulting mixture with a kneader. A kneading machine is not limited, For example, they are extruders, such as a single screw extruder and a twin screw extruder, and a pressure kneader. The obtained resin composition (C) may be pelletized with a pelletizer or the like, if necessary.

Resin composition (C) can be used, for example, as a resin molded body. A known method can be used for molding the resin molded body (C). For example, melt molding and solution molding can be used. When the resin molding is a film, for example, a known film molding method such as a solution casting method (solution casting method), a melt extrusion method, a calendar method, or a compression molding method can be employed. Of these, the solution casting method and the melt extrusion method are preferable.

Hereinafter, film forming by the melt extrusion method will be described. The same applies to the molding of resin molded bodies having other shapes.

The kneader used for melt extrusion of the resin composition (C) is not limited, and various types of extruders such as a single screw extruder and a twin screw extruder and known kneaders such as a pressure kneader can be used. The formation of the resin composition (C) and the molding of the resin composition (C) may be performed continuously. In one example, the resins (A) and (B), and the resin (A ) And (B) and other polymers and / or resins or additives are mixed by a known method, and this is melt-extruded. Specific examples of the melt extrusion method are a T-die method and an inflation method. The molding temperature at the time of melt extrusion molding is preferably 200 to 350 ° C., more preferably 250 to 300 ° C., further preferably 255 to 300 ° C., and particularly preferably 260 to 300 ° C. In the T-die method, a film (resin film) wound in a roll shape is obtained by extruding the resin composition (C) from an extruder having a T-die attached to the tip and winding the film extruded from the T-die. can get. The obtained film (unstretched film) may be further stretched, whereby a stretched film (uniaxially stretched film, biaxially stretched film) is obtained. A typical embodiment of the stretched film composed of the resin composition (C) is a biaxially stretched film. A known stretching machine can be used for stretching. For example, the film may be uniaxially stretched in the feeding direction (MD direction) by an oven longitudinal stretching machine or a roll longitudinal stretching machine, or the film may be stretched by a tenter transverse stretching machine. You may uniaxially stretch in the width direction (TD direction). Biaxial stretching can also be performed by combining stretching in the MD direction and stretching in the TD direction. The biaxial stretching may be not only sequential biaxial stretching but also simultaneous biaxial stretching by a simultaneous biaxial stretching machine.

More specifically, the type of the extruder is not limited, and any of short-shaft, twin-screw and multi-screw extruders can be employed. The L / D value of the extruder (L is the cylinder length of the extruder and D is the cylinder inner diameter) is preferably in order to sufficiently plasticize the resin composition and achieve a good kneading state. It is 10 or more and 100 or less, more preferably 15 or more and 80 or less, and further preferably 20 or more and 60 or less. Moreover, when the L / D value of an extruder exists in such a range, the excessive shear heat_generation | fever with respect to a resin composition will be suppressed, and the thermal decomposition of the resin contained in the said composition and the said composition will be suppressed.

The set temperature of the cylinder of the extruder is preferably 200 to 350 ° C., more preferably 250 to 300 ° C., similarly to the molding temperature in melt molding. When the set temperature is within these ranges, the melt viscosity of the resin composition in the extruder can be controlled to a range suitable for efficient melt molding, and the composition and the resin contained in the composition can be thermally decomposed. It is suppressed.

Although the specific configuration of the extruder is not limited, it is preferable that the extruder has one or more open vent portions. In this case, the decomposition gas generated by melting the resin composition in the extruder can be sucked from the open vent portion, and the amount of volatile components remaining in the formed film can be reduced. In order to suck the decomposition gas from the open vent portion, for example, the open vent portion may be in a reduced pressure atmosphere, and the degree of pressure reduction at that time is set to the pressure (absolute pressure) of the open vent portion, for example, 931 to 1. 3 hPa, preferably 798 to 13.3 hPa. Within these ranges, volatile components including monomer components generated by the decomposition of the resin can be removed more efficiently. Moreover, it is industrially difficult to keep the pressure of the open vent part of the extruder lower than 1.3 hPa.

When the resin composition is melt-extruded, it is preferable to perform filtration of the molten resin composition with a polymer filter. Thereby, since the quantity of the foreign material contained in a resin composition can be reduced, the fault on the external appearance by the said foreign material of the film obtained by melt molding can be reduced, for example. Since such a defect also becomes an optical defect of the resin molded body, the above filtration is particularly preferable when obtaining a resin molded body for optical use.

When performing filtration through a polymer filter, the molding temperature in melt molding is preferably 255 to 350 ° C., more preferably 260 to 320 ° C. Thereby, the viscosity (melt viscosity) of the resin composition in a molten state can be kept lower, and the residence time (passage time) of the resin composition in the polymer filter can be shortened. When the residence time is shortened, the deterioration of the resin composition in a high-temperature molten state that can occur when passing through the polymer filter is suppressed. For example, the gas component generated by the deterioration and / or the colored deterioration product resin composition Can be prevented. Incorporation of gas components and colored deterioration products can cause defects such as perforations, flow patterns, and flow lines in the obtained film. These drawbacks tend to occur when the film is continuously formed.

The filtration accuracy of the polymer filter is not limited and is usually 15 μm or less, preferably 10 μm or less, more preferably 5 μm or less. An excessively small filtration accuracy, for example, a filtration accuracy of 1 μm or less increases the residence time of the resin composition in the polymer filter, so that the degree of thermal deterioration of the resin composition during filtration increases, and the productivity of the resin molded body May decrease. On the other hand, excessively high filtration accuracy, for example, filtration accuracy exceeding 15 μm, reduces the removal rate of foreign substances contained in the resin composition.

The filtration area of the polymer filter is not limited and can be selected according to the treatment amount of the resin composition in the filter. The filtration area is, for example, 0.001 to 0.15 m ² / (kg / hour) as an area relative to the throughput per hour.

The shape of the polymer filter is not limited, for example, an internal flow type having a plurality of resin flow ports and a resin flow path in the center pole; the cross section is on the inner peripheral surface of the leaf disk filter at a plurality of vertices or faces And an external flow type having a resin flow path on the outer surface of the center pole. Outflow type is preferred because there are few resin stays.

The residence time of the resin composition in the polymer filter is not limited, but is preferably 20 minutes or less, more preferably 10 minutes or less, and even more preferably 5 minutes or less.

The filter inlet pressure and the filter outlet pressure during filtration are, for example, 3 to 15 MPa and 0.3 to 10 MPa, respectively. It is preferable to control the pressure loss during filtration (pressure difference between the filter inlet pressure and the outlet pressure) to 1 to 15 MPa. When the pressure loss is 1 MPa or less, the resin composition tends to be biased in the flow path through the filter, and the quality of the obtained film tends to decrease. On the other hand, when the pressure loss exceeds 15 MPa, the polymer filter is easily damaged during filtration. The temperature of the resin composition introduced into the polymer filter is, for example, 250 to 300 ° C., preferably 255 to 300 ° C., more preferably 260 to 300 ° C.

The specific process of forming a film with few defects such as foreign matters and colored substances by melt molding combined with filtration using a polymer filter is not limited. For example, (1) a process of forming and filtering a resin composition in a clean environment, and subsequently molding the resin composition in a clean environment; (2) cleaning a resin composition containing foreign matter and / or coloring matter; A process of molding a resin composition in a clean environment after filtration in an environment; (3) a process of molding and molding a resin composition containing foreign matter and / or color in a clean environment; Can be adopted. You may implement filtration of the resin composition by a polymer filter in multiple times for every process.

When filtering the resin composition with the polymer filter, it is preferable to arrange a gear pump between the extruder and the polymer filter to stabilize the pressure of the resin composition in the filter.

The resin composition that has passed through the polymer filter is preferably extruded as it is to form a film. In this case, since the thermal history of the resin composition can be reduced as compared with the case where the resin composition is pelletized and the obtained pellet is remelted to form a film, the thermal deterioration of the resin composition can be suppressed. Moreover, in this case, contamination of foreign matters from the environment can be further suppressed, and contamination and / or coloring of foreign matters in the obtained film can be further suppressed. When employing the T-die method, it is preferable to dispose a gear pump and a polymer filter between the extruder and the T-die.

The use of the resin composition (C) is not limited. A use can be selected according to the characteristic which a resin composition (C) can show. The characteristic is, for example, high heat resistance (Tg of 130 ° C. or higher); suppression of deterioration of mechanical characteristics, that is, retention of high mechanical characteristics. More specific examples are high flexibility, low dimensional change rate. Excellent optical properties, more specific examples are low birefringence, low photoelastic coefficient.

The specific use of the resin composition (C) is, for example, a resin molded body, and examples of the resin molded body include a film, a sheet, a plate, a substrate, a disk, a block, a ball, a lens, a rod, a strand, a cord, It is a fiber. Examples of more specific applications are various products such as mobile phones, keyboards, notebook computers, computer cases, game machines, cosmetics, stationery, sporting goods, and various industries such as the decoration industry and the information industry. , Decoration films used for surface decoration and functional panels in the telecommunications industry, automobile and motorcycle industry; optical members used in image display devices such as LCDs and OLEDs; A member of an apparatus (including an optical member) assumed to be used in a high-temperature environment such as a device that performs processing at a high temperature, such as a substrate of a transparent conductive film such as an ITO film.

Resin composition (C) may be an optical resin composition or an optical film resin composition.

[the film]
As an example of the application, a film (resin film); (F) composed of the resin composition (C) will be described.

The film (F) has characteristics derived from the resin composition (C). The film (F), for example, enjoys the excellent optical transparency possessed by the acrylic resin, and achieves high heat resistance, more specifically, high Tg of 130 ° C. or higher, while reducing mechanical properties. It is a film that is suppressed and is configured from a resin composition, and thus ensures the expected properties more reliably. The characteristics expected specifically are as described above.

Based on such characteristics, the film (F) is, for example, an optical member such as an optical film; a film included in a device expected to be used in a high temperature environment such as a device mounted on a vehicle; a transparent conductive film such as an ITO film; It can be used for a member that needs to be processed at a high temperature, such as a substrate film.

The thickness of the film (F) is, for example, 1 to 400 μm. When the film (F) is a protective film, an antireflection film, a polarizing film or the like used for an image display device such as an LCD or OLED, the thickness of the film (F) is preferably 1 to 250 μm, more preferably 10 to The thickness is 100 μm, more preferably 20 to 80 μm. When the film (F) is a substrate film of a transparent conductive film such as an ITO vapor-deposited film, a silver nanowire film, or a metal mesh film, the thickness of the film (F) is preferably 20 to 400 μm, more preferably 30 It is ˜350 μm, more preferably 40 to 300 μm.

The film (F) can have high optical transparency. The total light transmittance of the film (F) (total light transmittance evaluated in accordance with the provisions of JIS K7361) is, for example, 85% or more, depending on the composition of the resin composition (C) and the configuration of the film (F). Can be 90% or more, and further 91% or more. The total light transmittance of the film is an index of the optical transparency of the film. A film having a total light transmittance of less than 85% is not suitable for optical applications.

Film (F) may have a low haze. The haze of the film (F) (haze evaluated according to the provisions of JIS K7136) is, for example, 1.0% or less as a value in the thickness direction of the film per 100 μm of film thickness. The haze includes a total haze considering an effect derived from the shape of the film surface and an internal haze excluding the effect. The total haze and / or internal haze of the film (F) is set to the above value, for example, 1.0% or less. The internal haze can be 0.7% or less depending on the composition of the resin composition (C) and the structure of the film (F).

The film (F) is a stretched film and can be an optically isotropic film (low retardation film) whose birefringence is almost zero, more specifically, a retardation value is almost zero. . An optically isotropic film can be used as, for example, a polarizer protective film provided in an image display device, and a polarizing plate can be formed by combining the film with a polarizer. In this specification, when the phase difference (absolute value of the in-plane phase difference Re and the thickness direction phase difference Rth) with respect to light having a wavelength of 590 nm is 10 nm or less, there is no occurrence of orientation birefringence. Isotropic film (low retardation film). The absolute values of Re and Rth of the optically isotropic film are preferably 5 nm or less, more preferably 3 nm or less, and even more preferably 1 nm or less. That is, the film (F) is a stretched film, an in-plane retardation Re for light having a wavelength of 590 nm is 5 nm or less, and an absolute value of a thickness direction retardation Rth for the light may be 5 nm or less. .

Depending on the composition of the resin composition (C), for example, the composition of the resins (A) and (B) and the mixing ratio thereof, the film (F) is a stretched film and is not optically isotropic (optical Film having a certain anisotropy). Such a film showing a retardation can be used as, for example, a retardation film or an antireflection film combined with a polarizing plate. The low birefringence that the resin composition (C) and the film (F) composed of the composition may have is based solely on the high degree of freedom of birefringence control in the resin composition (C). The resin composition (C) and the film (F) are not limited to those exhibiting low birefringence. However, low birefringence combined with high Tg is one of the particularly advantageous effects of the present invention.

Film (F) can be a stretched film. More specifically, the film (F) can be a uniaxially stretched film or a biaxially stretched film. When the film (F) is a biaxially stretched film, the stretching direction is preferably an arbitrary direction in the film plane and a direction perpendicular to the direction in the film plane. When the film (F) has a strip shape, the arbitrary direction is, for example, its longitudinal direction (flow direction; MD), and the perpendicular direction is, for example, its width direction (TD). When the film (F) is a biaxially stretched film, the mechanical properties of the film in both the arbitrary direction and the perpendicular direction, such as flexibility, are improved.

The film (F) which is a stretched film can be formed by stretching an unstretched film of the resin composition (C). The minimum of extending | stretching temperature is Tg or more, for example, and it is more preferable in order of Tg + 5 degreeC or more, Tg + 10 degreeC or more, and Tg + 15 degreeC or more. The upper limit of the stretching temperature is, for example, Tg + 40 ° C. or lower, and more preferable in the order of Tg + 35 ° C. or lower, Tg + 30 ° C. or lower, and Tg + 25 ° C. or lower. When the stretching temperature increases, the effect of improving the strength based on the orientation of the molecular chain of the polymer contained in the resin composition decreases, but the dimensional change rate of the film at a high temperature tends to be suppressed to a low level. On the other hand, when the stretching temperature is lowered, the effect of improving the strength is enhanced, but the dimensional change rate at a high temperature tends to be increased.

The stretching ratio in the above-mentioned arbitrary direction in biaxial stretching, for example, the MD direction is, for example, 1.3 to 1.9 times, preferably 1.4 to 1.9 times. When the draw ratio is excessively small, the orientation of the molecular chain in the stretched film cannot be sufficiently ensured. For example, the flexibility of the film, more specifically, the flexibility in the MD direction is expected to be expected by stretching. Will not be achieved. A film with low flexibility may be whitened by bending, for example.

In the biaxial stretching, the stretching ratio in the perpendicular direction, for example, the TD direction, is, for example, 1.8 to 4.0 times, preferably 2.0 to 3.8 times. If the draw ratio is excessively small, the orientation of the molecular chain in the stretched film cannot be sufficiently secured, and for example, the flexibility of the film, more specifically, the flexibility in the TD direction is expected to be expected by stretching. Will not be achieved. A film with low flexibility may be whitened by bending, for example.

The stretching speed is preferably 10 to 20,000% / min, more preferably 100 to 10,000% / min per one direction of stretching. In these cases, a stretched film can be formed more efficiently while preventing breakage during film stretching.

The film (F) is a stretched film, more specifically a biaxially stretched film, which has a folding resistance of 200 times or more in a folding resistance test (MIT test) performed based on the provisions of JIS P8115. It can be the film shown. When the number of folding times varies depending on the film direction, for example, when the number of folding times in the MD direction is different from the number of folding times in the TD direction, the smaller number of times can be 200 or more. Depending on the configuration of the resin composition (C) and the configuration of the film (F), for example, the stretched state of the film (F), the film (F) may be 250 times or more, 300 times or more, or 350 times in the folding resistance test. It may be a film showing the number of folding times more than the number of times. Such a film (F) has high flexibility, prevents breakage during production, and is excellent in handling and durability when used, particularly as an optical member.

The film (F) is a stretched film, more specifically, a biaxially stretched film, and the dimensional change rate before and after the test is -1. The film may be 5% or more and 0.5% or less. Depending on the composition of the resin composition (C) and the composition of the film (F), for example, the stretched state of the film (F), the film (F) has a lower limit of the dimensional change rate of −1.2% or more, and −1. The film may be 0% or more, more preferably −0.8% or more, and the upper limit of the dimensional change rate may be 0.3% or less, further 0.1% or less. Such a film has heat resistance that can withstand processing at high temperatures, and is excellent in durability at high temperatures. A negative dimensional change value indicates that the film has shrunk by the test.

The film (F) is a stretched film, more specifically a biaxially stretched film, and a dimensional change before and after the test in a 120-hour wet heat durability test in a high-temperature wet state at 85 ° C. and a relative humidity of 95% RH. The film may have a rate of −1.5% to 0.5%. Depending on the composition of the resin composition (C) and the composition of the film (F), for example, the stretched state of the film (F), the film (F) has a lower limit of the dimensional change rate of −1.2% or more, and −1. The film may be 0% or more, further −0.8% or more, and the upper limit of the dimensional change rate may be 0.3% or less, further 0.1% or less. Such a film has heat resistance capable of withstanding processing at high temperature and high humidity, and is excellent in durability when used at high temperature and high humidity.

Film (F) is an antistatic layer, an adhesive layer, an adhesive layer, an easy-adhesion layer, an antiglare (non-glare) layer, an antifouling layer such as a photocatalyst layer, an antireflection layer, or a hard coat layer as necessary. Further, various functional layers such as an ultraviolet shielding layer, a heat ray shielding layer, an electromagnetic wave shielding layer, a light diffusion layer, a gas barrier layer, and a transparent conductive layer may be further included. These functional layers may be a coating layer of the film (F) applied on the surface of the film (F), or an independent layer laminated on the film (F) via an adhesive or an adhesive. It may be. The film (F) may have two or more functional layers, and for the laminate of the film (F) and the functional layer, the laminate has two or more films (F). Also good. The order of laminating the functional layers on the film (F) and the laminating method are not limited.

The use of the film (F) is not limited, and is, for example, use as an optical member (optical use). Optical members include, for example, a polarizer protective film, a retardation film, a viewing angle compensation film, a light diffusion film, a reflection film, an antireflection film, an antiglare film, a brightness enhancement film, a conductive film for touch panels, and various optical disks used for polarizing plates. (VD, CD, DVD, MD, LD, etc.) A substrate protective film, a diffusion plate, a light guide, a retardation plate, and a prism sheet. The film (F) which shows small birefringence can be used suitably for a polarizer protective film, for example. Moreover, the film (F) which shows a small photoelastic coefficient with small birefringence can satisfy | fill the performance of the low phase difference and low photoelasticity which are requested | required on the market. The high heat resistance that can be exhibited by the film (F) makes the effect of the use of the film (F) for in-vehicle devices more remarkable.

Film (F) can be a strip-shaped film. The band-shaped film (F) can be efficiently manufactured and processed by, for example, roll-to-roll. More specific examples of the production and processing are production of a polarizing plate by bonding with a polarizing film, formation of a transparent conductive film by sputtering or vapor deposition on the film (F), and formation of a functional layer by coating. is there.

Hereinafter, the present invention will be described in more detail with reference to examples. The present invention is not limited to the examples shown below. Hereinafter, “%” represents “% by weight”, and “part” represents “part by weight”.

In the examples, the following abbreviations are used for compounds.

MMA: Methyl methacrylate MHMA: Methyl 2- (hydroxymethyl) acrylate PMI: N-phenylmaleimide AN: Acrylonitrile St: Styrene MEK: Methyl ethyl ketone MIBK: Methyl isobutyl ketone

In this example, since the resin contains only one specific polymer, the polymer and the resin are the same.

First, the evaluation method of the characteristics of the resin, resin composition and film produced in the examples will be shown.

[Weight average molecular weight]
The weight average molecular weight Mw of the resin was determined by gel permeation chromatography (GPC) according to the following measurement conditions.
Measurement system: “GPC system HLC-8220” manufactured by Tosoh Corporation
Developing solvent: Chloroform (Wako Pure Chemical Industries, special grade)
Solvent flow rate: 0.6 mL / min Standard sample: TSK standard polystyrene (“PS-oligomer kit” manufactured by Tosoh Corporation)
Measurement side column configuration: guard column (“TSK guardcolumn Super HZ-L” manufactured by Tosoh), separation column (“TSK Gel Super HZM-M” manufactured by Tosoh), two in-line connection Reference side column configuration: reference column (“TSK manufactured by Tosoh” gel SuperH-RC ")

[Glass-transition temperature]
The glass transition temperature Tg of the resin and the resin composition was measured in accordance with JIS K7121 regulations. Specifically, using a differential scanning calorimeter (“Thermo plus EVO DSC-8230” manufactured by Rigaku), a sample of about 10 mg was heated from normal temperature to 200 ° C. (temperature increase rate: 20 ° C./min) in a nitrogen gas atmosphere. From the DSC curve obtained in this way, it was determined by the starting point method. Α-alumina was used as a reference.

[Stress optical coefficient]
The stress optical coefficient Cr of the resin composition was evaluated as follows. The resin composition to be evaluated was formed into a film by a melt press to produce an unstretched film (thickness: 100 μm). Next, the produced unstretched film was cut into a 60 mm × 20 mm rectangle to be an evaluation sample, and a weight selected so that a stress of 1 N / mm ² or less was applied to the sample was attached to one of the short sides of the sample. Next, the sample was set in a constant temperature dryer (DOV-450A, manufactured by AS ONE) with a chuck distance of 40 mm so that the attached weight became the lower end. The set temperature of the constant temperature dryer was set to Tg + 3 ° C. of the resin composition to be evaluated, and the constant temperature dryer was preheated to the temperature before setting the sample. After setting the sample, the sample was held for about 30 minutes without changing the set temperature of the constant temperature dryer, thereby uniaxially stretching the sample based on the load of the attached weight. Next, the constant temperature dryer was cooled at a cooling rate of about 1 ° C./min until the temperature inside the device reached Tg−40 ° C. of the resin composition. After cooling, the film was taken out from the dryer, and the length and thickness of the stretched film, the weight of the weight, and the in-plane retardation Re of the stretched film with respect to light having a wavelength of 590 nm were measured. The same measurement was performed four times on one resin composition while changing the weight of the weight, and the stress optical coefficient Cr of the resin composition was calculated from the result. The calculation method of Cr is described in “Forefront of Transparent Plastics (Edited by Society of Polymer Science)” pp. The method described in 37-44 was followed. Specifically, from the in-plane retardation Re and thickness of the stretched film, the Δn (= nx−ny) of the film is calculated from the weight and the length and thickness of the stretched film. The stretching stress σ (unit: N / m ² ) applied to is obtained, and Δn and σ obtained by four measurements are set as coordinates with Δn as a value on the vertical axis and σ as a value on the horizontal axis, This was plotted. Next, the slope of the approximate straight line connecting the four plotted points was determined by the method of least squares, and this was used as Cr of the resin composition. nx is the refractive index in the slow axis direction in the plane of the film (the direction showing the maximum refractive index in the film plane), and ny is the fast axis direction in the plane of the film (perpendicular to nx in the film plane). Direction). The in-plane phase difference Re is given by the equation (nx−ny) × d. d is the thickness of the film (unit: μm). A method for measuring the in-plane retardation Re will be described later.

[Photoelastic coefficient]
The photoelastic coefficient of the resin composition with respect to light having a wavelength of 590 nm was evaluated using an ellipsometer (manufactured by JASCO, M-150) as follows. First, the resin composition to be evaluated was formed into a film by a melt press to produce an unstretched film (thickness: 100 μm). Next, the produced unstretched film was cut into a size of 20 mm × 50 mm to obtain a measurement sample. Next, the cut-out measurement sample is mounted in an ellipsometer photoelasticity measurement unit, and three-point birefringence is measured while applying a stress load of 5 to 25 N parallel to the long side direction of the sample, and light having a wavelength of 590 nm is measured. The slope of birefringence with respect to the stress when using was used as the photoelastic coefficient of the resin composition.

[Film thickness]
The thickness of the film was measured using a Digimatic Micrometer (Mitutoyo).

[Haze]
The haze of the film was measured using a turbidimeter (manufactured by Nippon Denshoku Industries Co., Ltd., NDH 5000) in accordance with JIS K7136: 2000. Table 1 shows values converted per film thickness of 100 μm. In addition, haze was measured in the state which immersed the film which is a measuring object in the tetralin in a quartz cell. That is, the measured haze was internal haze.

[optical properties]
In-plane retardation Re and thickness direction retardation Rth for light with a wavelength of 590 nm of the film were measured using a retardation film / optical material inspection apparatus RETS-100 (manufactured by Otsuka Electronics Co., Ltd.) at an incident angle of 40 °. did. The in-plane retardation Re and the thickness direction retardation Rth are the refractive index in the slow axis direction in the plane of the film nx, the refractive index in the fast axis direction in the film plane ny, and the thickness direction of the film Where nz is the refractive index and d is the thickness of the film.
In-plane retardation Re = (nx−ny) × d
Thickness direction retardation Rth = {(nx + ny) / 2−nz} × d

[Intrinsic birefringence]
The positive / negative of the intrinsic birefringence of the resin was evaluated as follows. The phase difference of a uniaxially stretched film composed of the resin to be measured is measured by the above method, and the resin is used when the slow axis direction of the film determined by the measurement is parallel to the stretch direction of the film (including the case of being substantially parallel). The intrinsic birefringence of the resin was negative, and the intrinsic birefringence of the resin was negative when the slow axis direction of the film was perpendicular to the stretching direction of the film (including the case of being substantially perpendicular). A uniaxially stretched resin film was prepared as follows. First, the resin composition to be evaluated was formed into a film by a melt press to produce an unstretched film (thickness: 100 μm). Next, the produced unstretched film was cut into a size of 80 mm × 50 mm. Next, using the autograph (manufactured by Shimadzu Corp., AG-1kNX), the cut film was stretched from the initial state where the distance between chucks was 40 mm under the stretching temperature (Tg + 10) ° C. and the stretching speed of 40 mm / min. A uniaxially stretched film was obtained by uniaxial stretching at a free end of 2 times.

[Fold resistance (MIT)]
The number of folding resistances of the film was evaluated in accordance with JIS P8115. Specifically, a measurement sample having a length of 90 mm and a width of 15 mm was cut out from the film and allowed to stand in an atmosphere of 23 ° C. and 50% relative humidity (RH) for 1 hour or longer. The sample was subjected to a bending test under the conditions of a bending angle of 135 °, a bending speed of 175 cpm, and a load of 200 g. Five samples were prepared for one film, and the average of the measured values of each sample was defined as the number of folding times of the film. Evaluation of the folding endurance number was performed for each of the case where the MD direction of the film was the length direction of the sample and the case where the TD direction was the length direction of the sample.

[Durability test (dimensional change rate)]
The durability (dimensional change rate) of the film was evaluated as follows. First, the film was cut out to produce three 80 mm × 80 mm square measurement samples. Next, the length (La1, La2, La3, La4) of the four sides of the cut out sample was measured with a digital caliper. Next, the sample was stored for 120 hours in a constant temperature bath set to 110 ° C. or a constant temperature bath set to 85 ° C. and relative humidity (RH) 95%, and the length of the four pieces of the sample (Lb1, Lb2 after storage) , Lb3, Lb4) were measured again.

Next, the dimensional change rate of each side of the sample before and after storage is obtained by the formula: dimensional change rate = | (Lb−La) / La | × 100 (%), and the total average of the three samples and the four sides is calculated as a film. The rate of dimensional change was In the above formula, La is the length of one side of the film before storage, and Lb is the length of one piece of the film after storage.

[Content of constituent unit derived from N-substituted maleimide monomer in resin composition]
The content of the structural unit derived from the N-substituted maleimide monomer in the resin composition was determined as follows. The content of the structural unit in a resin having a structural unit derived from an N-substituted maleimide monomer (in this example, a resin having a negative intrinsic birefringence) is measured using an NMR measuring apparatus (Varian, Unity Plus 400). And determined by measuring the ¹ H-NMR spectrum of the resin. More specifically, the resin to be evaluated (weight a) and 1,1,2,2-tetrachloroethane (molecular weight 167.85, weight b) as an internal standard were dissolved in deuterated chloroform, and the internal standard in the measured spectrum was measured. From the area ratio (X / Y) between the peak area X of (chemical shift 5.9 ppm, 4 protons) and the peak area Y derived from the protons of the groups R ¹ and R ² of the structural unit, The content rate of the said structural unit in resin was calculated | required. For example, when the groups R ¹ and R ^{2 of the} structural unit are both hydrogen atoms and R ³ is a phenyl group, the content of the structural unit in the resin is 2/4 × 173.17 / 167.85. Xb / a * (Y / X) * 100 (% by weight). Next, from the weight ratio of the obtained content and the resin in the resin composition and other resin (in this example, a resin having positive intrinsic birefringence), the content of the structural unit in the resin composition The rate was calculated.

[Dealcoholization reaction rate (lactone cyclization rate)]
The content of the ring structure in the resin having a lactone ring structure in the main chain was evaluated as follows.

In this example, a lactone ring structure was formed by intramolecular cyclocondensation reaction (dealcoholization cyclocondensation reaction between MMA unit and MHMA unit) in the precursor polymer. Based on the weight reduction rate of the polymer when it is assumed that all hydroxyl groups (hydroxyl groups derived from MHMA units) contained in the precursor polymer have been dealcoholated as methanol, the actually produced resin is heated to the resin. The weight loss rate due to dealcoholization of the remaining hydroxyl group as methanol was measured and compared with the above criteria to determine the lactone ring content.

Specifically, dynamic TG measurement was performed on the prepared resin (here, a polymer having a lactone ring structure in the main chain), and the weight reduction rate (measured weight) of the resin between 150 ° C. and 300 ° C. The reduction rate P) was measured. 150 ° C. corresponds to a temperature at which a hydroxyl group remaining in the resin starts a dealcoholization reaction, and 300 ° C. corresponds to a temperature at which the resin starts to decompose. Separately from this, the theoretical weight loss rate Q was calculated from the composition of the precursor polymer, assuming that all the hydroxyl groups contained in the precursor polymer were involved in the formation of the lactone ring, that is, dealcoholized. More specifically, the theoretical weight reduction rate Q was calculated from the content of constituent units (constituent units having a hydroxyl group) involved in the dealcoholization reaction in the precursor polymer. Next, from the measured weight reduction rate P and the theoretical weight reduction rate Q, the dealcohol content of the resin to be evaluated is determined according to the formula: {1- (actual weight reduction rate P / theoretical weight reduction rate Q)} × 100 The reaction rate (%) was determined. The dealcoholized reaction rate corresponds to the amount of structural units that have undergone a cyclization reaction during the production of a polymer having a lactone ring structure in the main chain to be evaluated from the precursor polymer. Then, the content of the lactone ring structure in the resin was determined according to the formula: B × A × MR / Mm, assuming that the lactone cyclization reaction proceeded during the resin preparation by the determined dealcoholization reaction rate. B is the content of the constituent unit (constituent unit having a hydroxyl group) involved in the lactone cyclization reaction in the precursor polymer (the polymer before the lactone cyclization reaction proceeds), and MR is determined by the cyclization reaction. The formula weight of the lactone ring structure to be formed, Mm is the molecular weight of the structural unit, and A is the dealcoholization reaction rate.

(Example 1: Production of resin composition P1)
(Preparation of acrylic resin A1 having positive intrinsic birefringence)
Into a reaction vessel having an internal volume of 30 L equipped with a stirrer, a temperature sensor, a cooling pipe, and a nitrogen introduction pipe, 8000 g of MMA, 2000 g of MHMA, and 10,000 g of toluene as a polymerization solvent were charged, and nitrogen was passed through to 105 ° C. The temperature rose. When refluxing with increasing temperature started, 10.0 g of t-amyl peroxyisononanoate (manufactured by Arkema Yoshitomi, Luperox 570, hereinafter the same) was added as a polymerization initiator. Subsequently, while a solution consisting of 20.0 g of t-amylperoxyisononanoate and 100 g of toluene was added dropwise over 2 hours, solution polymerization was allowed to proceed under reflux at about 105 to 110 ° C. Aged over time.

Next, 10 g of stearyl phosphate / distearyl phosphate mixture (Phoslex A-18, manufactured by Sakai Chemical Co., Ltd.) as a cyclization catalyst was added to the polymerization solution thus obtained, and 5 ° C. under reflux at about 90 to 120 ° C. The cyclization condensation reaction in which a lactone ring structure was formed was allowed to proceed over time. Subsequently, the polymerization solution was heated and pressurized by an autoclave using a heating medium at 240 ° C., and the cyclization condensation reaction was allowed to proceed for an additional 1.5 hours. The pressure of the autoclave was set to a maximum of about 2 MPa as a gauge pressure.

Next, the polymerization solution thus obtained was set to a barrel temperature of 260 ° C., a rotation speed of 100 rpm, and a degree of vacuum of 13.3 to 400 hPa (10 to 300 mmHg), and a vent having one rear vent and four forevents. By introducing into a type screw twin screw extruder (φ = 30 mm, L / D = 40) at a processing rate of 2.0 kg / hour in terms of resin amount, further progress of cyclization condensation reaction and devolatilization in the extruder And further extruding from the tip thereof to obtain a transparent pellet of acrylic resin A1 having a lactone ring structure in the main chain. The weight average molecular weight Mw of the resin A1 is 1480,000, the glass transition temperature Tg is 130 ° C., the intrinsic birefringence is positive, the lactone ring content is 29.2%, and the stress optical coefficient Cr is 4.2 × 10 ⁻¹⁰ Pa. ^-1 .

(Production of resin B1 having negative intrinsic birefringence)
Into a reaction vessel having an internal volume of 30 L equipped with a stirrer, a temperature sensor, a cooling pipe and a nitrogen introduction pipe, 3200 g of PMI, 1400 g of AN, 5400 g of St, and 10000 g of toluene as a polymerization solvent were charged, and nitrogen was passed through this. The temperature was raised to 105 ° C. When refluxing with increasing temperature started, 6.0 g of t-amylperoxyisononanoate was added as a polymerization initiator, and solution polymerization was allowed to proceed under reflux at about 105 to 110 ° C.

Next, the polymerization solution thus obtained was set to a barrel temperature of 260 ° C., a rotation speed of 100 rpm, and a degree of vacuum of 13.3 to 400 hPa (10 to 300 mmHg), and a vent having one rear vent and four forevents. Volatilization was carried out by introducing it into a type screw twin screw extruder (φ = 30 mm, L / D = 40) at a processing rate of 2.0 kg / hour in terms of the amount of resin. A transparent pellet of resin B1 having an N-substituted maleimide structure (PMI structure) in the chain was obtained. The weight average molecular weight Mw of the resin B1 was 153,000, the glass transition temperature Tg was 146 ° C., the intrinsic birefringence was negative, and the stress optical coefficient Cr was −24.8 × 10 ⁻¹⁰ Pa ⁻¹ . In addition, the content of the N-substituted maleimide structure in resin B1 (the content of the structural unit derived from the N-substituted maleimide monomer) was 31.6%.

(Preparation of resin composition P1)
The resin A1 and the resin B1 produced as described above were kneaded at 260 ° C. using a twin screw extruder (φ = 30 mm, L / D = 40) so that the weight ratio of A1 / B1 = 89/11. Thus, a pellet-shaped resin composition P1 was obtained. The content of the N-substituted maleimide structure in the resin composition P1 was 3.5%, and the content of the lactone ring structure was 26.0% by weight. The Tg, stress optical coefficient Cr, photoelastic coefficient, and haze of the resin composition P1 are summarized in Table 1 below. Only one point was measured for the Tg of the resin composition P1, that is, it was confirmed that the resin A1 and the resin B1 were compatible in the resin composition P1.

(Example 2)
(Preparation of resin composition P2)
Using a twin screw extruder (φ = 30 mm, L / D = 40), the resin A1 and the resin B1 produced as described above were mixed at a weight ratio of A1 / B1 = 87.4 / 12.6. The mixture was kneaded at 0 ° C. to obtain a pellet-shaped resin composition P2. In resin composition P2, the content of the N-substituted maleimide structure was 4.0%, and the content of the lactone ring structure was 25.5% by weight. Table 1 below summarizes the Tg, stress optical coefficient Cr, photoelastic coefficient, and haze of the resin composition P2. Only one point was measured for the Tg of the resin composition P2, that is, it was confirmed that the resin A1 and the resin B1 were compatible in the resin composition P2.

(Example 3)
(Preparation of resin composition P3)
The resin A1 and the resin B1 produced as described above were kneaded at 260 ° C. using a twin-screw extruder (φ = 30 mm, L / D = 40) so as to have a weight ratio of A1 / B1 = 86/14. Thus, a pellet-shaped resin composition P3 was obtained. In resin composition P3, the content of the N-substituted maleimide structure was 4.4%, and the content of the lactone ring structure was 25.1% by weight. Table 1 below summarizes the Tg, stress optical coefficient Cr, photoelastic coefficient, and haze of the resin composition P2. Only one point of Tg of the resin composition P3 was measured, that is, it was confirmed that the resin A1 and the resin B1 were compatible in the resin composition P3.

(Comparative Example 1)
(Preparation of resin composition P4)
Resin A1 prepared as described above and styrene-acrylonitrile copolymer B2 having negative intrinsic birefringence (weight ratio of styrene / acrylonitrile is 73/27, weight average molecular weight 220,000, stress optical coefficient Cr is −28. 9 × 10 ⁻¹⁰ Pa ⁻¹ ) pellets at 240 ° C. using a twin screw extruder (φ = 30 mm, L / D = 40) so as to have a weight ratio of A1 / B2 = 90/10 As a result, a pellet-shaped resin composition P4 was obtained. The resin composition P4 did not have an N-substituted maleimide structure, and the content of the lactone ring structure in the resin composition P4 was 26.3%. Table 1 below summarizes Tg, stress optical coefficient Cr, photoelastic coefficient, and haze of resin composition P4. Only one point of Tg of the resin composition P4 was measured, that is, it was confirmed that the resin A1 and the resin B2 were compatible in the resin composition P4.

(Comparative Example 2: Production of resin composition P5)
(Preparation of acrylic resin A2 having positive intrinsic birefringence)
Into a reaction vessel having an internal volume of 30 L equipped with a stirrer, a temperature sensor, a cooling pipe and a nitrogen introducing pipe, 7000 g of MMA, 3000 g of MHMA, and 6667 g of a mixed solvent of MIBK and MEK (weight ratio 9: 1) as a polymerization solvent. The temperature was raised to 105 ° C. while introducing nitrogen into the mixture. When refluxing with increasing temperature started, 6.0 g of t-amylperoxyisononanoate was added as a polymerization initiator. Subsequently, while a solution consisting of 12.0 g of t-amylperoxyisononanoate and 3315 g of the above mixed solvent was dropped over 3 hours, solution polymerization was allowed to proceed under reflux at about 95 to 110 ° C., The aging was further performed for 4 hours.

Next, 20 g of an octyl phosphate / dioctyl phosphate mixture is added to the polymerization solution thus obtained as a cyclization catalyst, and cyclization in which a lactone ring structure is formed at reflux of about 85 to 100 ° C. for 2 hours. The condensation reaction was allowed to proceed. Subsequently, the polymerization solution was heated and pressurized by an autoclave using a heating medium at 240 ° C., and the cyclization condensation reaction was allowed to proceed for an additional 1.5 hours. The pressure of the autoclave was set to a maximum of about 2 MPa as a gauge pressure.

Next, the polymerization solution thus obtained was introduced into a twin-screw extruder in the same manner as in Example 1 and further cyclization condensation reaction proceeded and devolatilized in the extruder, and further extruded from its tip. Thus, a transparent pellet of acrylic resin A2 having a lactone ring structure in the main chain was obtained. The weight average molecular weight Mw of the resin A2 is 1270, glass transition temperature Tg is 140 ° C., intrinsic birefringence is positive, lactone ring content is 43.9%, and the stress optical coefficient Cr is 6.5 × 10 ⁻¹⁰ Pa. ^-1 .

(Preparation of resin composition P5)
A resin A2 produced as described above and a styrene-acrylonitrile copolymer B2 having negative intrinsic birefringence are mixed into a twin-screw extruder (φ = 30 mm, φ / mm) so that the weight ratio is A1 / B2 = 82/18. L / D = 40) and kneading at 260 ° C. to obtain a pellet-shaped resin composition P5. The resin composition P5 did not have an N-substituted maleimide structure, and the content of the lactone ring structure in the resin composition P5 was 36.0%. Table 1 below summarizes Tg, stress optical coefficient Cr, photoelastic coefficient, and haze of resin composition P5. Only one point of Tg of the resin composition P5 was measured, that is, it was confirmed that the resin A2 and the resin B2 were compatible in the resin composition P5.

Example 4
The resin composition P2 produced in Example 2 was melt-extruded from a coat hanger type T die (width 150 mm, T die temperature 260 ° C.) using a single screw extruder (φ = 20 mm, L / D = 25). This was discharged onto a cooling roll having a roll temperature of 130 ° C. to produce an unstretched film having a thickness of 160 μm.

Next, after cutting the obtained unstretched film into 96 mm × 96 mm, using a sequential biaxial stretching machine (manufactured by Toyo Seiki Seisakusho, X-6S), a stretching temperature of 147 ° C. (= Tg + 15 ° C.), 240 mm / min. Biaxial stretching was performed sequentially at a stretching ratio of 2 in the longitudinal direction and the transverse direction (MD direction and TD direction) at the stretching speed of. After stretching, the film was quickly taken out from the test apparatus and cooled to obtain a biaxially stretched film F1 having a thickness of 40 μm. The evaluation results of the obtained film F1 are summarized in Table 2 below.

(Example 5)
A biaxially stretched film F2 having a thickness of 40 μm was obtained in the same manner as in Example 4 except that the stretching temperature was changed to 152 ° C. (= Tg + 20 ° C.). The evaluation results of the obtained film F2 are summarized in Table 2 below.

(Comparative Example 3)
The resin composition P4 produced in Comparative Example 1 was melt extruded from a coat hanger type T die (width 150 mm, T die temperature 250 ° C.) using a single screw extruder (φ = 20 mm, L / D = 25). This was discharged onto a cooling roll having a roll temperature of 120 ° C. to produce an unstretched film having a thickness of 160 μm.

Next, after cutting the obtained unstretched film to 96 mm × 96 mm, using a sequential biaxial stretching machine (X-6S, manufactured by Toyo Seiki Seisakusho), a stretching temperature of 145 ° C. (= Tg + 20 ° C.), 240 mm / min. The film was sequentially biaxially stretched at a stretching ratio of 2 in the order of the longitudinal direction and the transverse direction (MD direction and TD direction) at a stretching speed of. After stretching, the film was quickly taken out from the test apparatus and cooled to obtain a biaxially stretched film F3 having a thickness of 40 μm. The evaluation results of the obtained film F3 are summarized in Table 2 below.

(Comparative Example 4)
Similar to Comparative Example 3, except that the resin composition P5 prepared in Comparative Example 2 was used instead of the resin composition P4 and the stretching temperature was changed to 151 ° C. (= Tg + 20 ° C.). An axially stretched film F4 was obtained. The evaluation results of the obtained film F4 are summarized in Table 2 below.

(Example 6)
(Preparation of rubber polymer G1)
In a polymerization vessel equipped with a cooler and a stirrer, 710 parts of deionized water and 1.5 parts of sodium lauryl sulfate were added and dissolved, and the internal temperature was raised to 70 ° C. Next, a mixed solution of 0.93 part of sodium formaldehyde sulfoxylate (SFS), 0.001 part of ferrous sulfate, 0.003 part of disodium ethylenediaminetetraacetate (EDTA), and 20 parts of deionized water is polymerized. After further charging into the vessel all at once, the inside of the polymerization vessel was sufficiently replaced with nitrogen gas. Next, a monomer mixed solution of 7.1 parts of butyl acrylate (BA), 2.9 parts of St, 0.02 part of 1,4-butanediol dimethacrylate (BDMA) and 0.02 part of allyl methacrylate (AMA) M-1 and a polymerization initiator solution of 0.13 part of t-butyl hydroperoxide (PBH) and 10.0 parts of deionized water are further added to the polymerization vessel all at once, and the polymerization reaction is performed for 60 minutes. Made progress. Next, a monomer mixture M2 of 63.9 parts of BA, 25.2 parts of St and 0.9 part of AMA, and a polymerization initiator solution of 0.246 parts of PBH and 20.0 parts of deionized water were separately added over 90 minutes. While continuously dropping into the polymerization vessel, further polymerization reaction was allowed to proceed, and the polymerization reaction was continued for another 60 minutes after the completion of these droppings. Through this series of reactions, a rubber polymer core-shell part was obtained.

Next, a monomer mixture M3 of 73.0 parts of St and acrylonitrile (AN) 27.0 parts, and a polymerization initiator solution of 0.27 parts of PBH and 20.0 parts of deionized water were continuously separated over 100 minutes. Further polymerization reaction was allowed to proceed while dropping, and the polymerization reaction was continued for 120 minutes by raising the internal temperature of the polymerization vessel to 80 ° C. even after completion of these droppings. Next, after the polymerization container was cooled to an internal temperature of 40 ° C., the contents were passed through a 300-mesh wire mesh to obtain an emulsion polymerization solution of a rubber polymer having a core / shell structure. Next, the obtained emulsion polymerization solution was salted out and coagulated with calcium chloride, and then the solid was washed with water and dried to obtain a powdery rubber polymer G1 (average particle size 0.105 μm).

(Preparation of resin composition P6)
The resin A1 and the resin B1 produced as described above, and the rubber polymer G1 were mixed with a twin-screw extruder (φ = 30 mm, L / L) so that the weight ratio A1 / B1 / G1 = 85/10/5. D = 40) and kneaded at 260 ° C. to obtain a pellet-shaped resin composition P6. In resin composition P6, the content of the N-substituted maleimide structure was 3.2%, and the content of the lactone ring structure was 23.4%. The Tg, stress optical coefficient Cr, photoelastic coefficient, and haze of the resin composition P6 are summarized in Table 1 below. Only one point of Tg of the resin composition P6 was measured, that is, it was confirmed that the resin A1 and the resin B1 were compatible in the resin composition P6.

(Example 7)
(Preparation of resin composition P7)
The resin A1 and the resin B1 produced as described above, and the rubbery polymer G1 were mixed with a twin-screw extruder (φ = 1 / B1 / G1 = 80.5 / 12 / 7.5). 30 mm, L / D = 40) and kneading at 260 ° C. to obtain a pellet-shaped resin composition P7. In resin composition P7, the content of the N-substituted maleimide structure was 3.8%, and the content of the lactone ring structure was 23.5%. Table 1 below summarizes the Tg, stress optical coefficient Cr, photoelastic coefficient, and haze of the resin composition P7. Only one point of Tg of the resin composition P7 was measured, that is, it was confirmed that the resin A1 and the resin B1 were compatible in the resin composition P7.

(Example 8)
In the same manner as in Example 4, except that the resin composition P6 prepared in Example 6 was used instead of the resin composition P2, and the stretching temperature was changed to 149 ° C. (= Tg + 18 ° C.). An axially stretched film F5 was obtained. The evaluation results of the obtained film F5 are summarized in Table 2 below.

Example 9
In the same manner as in Example 4, except that the resin composition P7 prepared in Example 7 was used instead of the resin composition P2, and the stretching temperature was changed to 149 ° C. (= Tg + 18 ° C.). An axially stretched film F6 was obtained. The evaluation results of the obtained film F6 are summarized in Table 2 below.

As shown in Table 1, in the resin compositions of the examples, high Tg of 130 ° C. or higher and small Cr were realized even though the ring structure content in the resin composition was 30% by weight or less. On the other hand, in the resin composition of Comparative Example 1 which does not contain an N-substituted maleimide structure and the content of the ring structure in the resin composition is the same as that of the example, a small Cr can be achieved while Tg reaches 130 ° C. I did not. Similarly, in the resin composition of Comparative Example 2 that does not contain an N-substituted maleimide structure, in order to realize a high Tg of 130 ° C. or higher and a small Cr, the content ratio in the resin composition is 36% by weight. It was necessary to contain a ring structure, which forced an increase in the photoelastic coefficient and an extreme decrease in the folding resistance of the film of Comparative Example 4 in Table 2. In addition, the photoelastic coefficient became high also in the resin composition of the comparative example 1. Further, as shown in the stretched film of Comparative Example 3 prepared from the resin composition P4 of Comparative Example 1 and Comparative Example 1, the resin composition having no N-substituted maleimide structure has the same folding resistance. In this case, the dimensional change rate was larger than that of the resin composition of the example. As shown in Examples 1 and 2, when the content of the N-substituted maleimide structure in the resin composition increases, the folding resistance of the film decreases, that is, the resin composition tends to become hard and brittle. However, the folding resistance of the examples relative to the comparative example increased despite the inclusion of the N-substituted maleimide structure. That is, the resin compositions of the examples contained N-substituted maleimide structures and were flexible despite achieving high Tg.

The present invention can be applied to other embodiments without departing from the intent and essential features thereof. The embodiments disclosed in this specification are illustrative in all respects and are not limited thereto. The scope of the present invention is shown not by the above description but by the appended claims, and all modifications that fall within the meaning and scope equivalent to the claims are embraced therein.

The resin composition of the present invention can be used after being formed into various shapes such as a film and a substrate. The resin composition of the present invention can be used, for example, as an optical member, and more specifically as an optical film or an optical substrate. Focusing on the high Tg, it can be used in applications that are expected to be used in high-temperature environments, such as being incorporated into equipment mounted on vehicles, or in applications that are exposed to high-temperature processing such as transparent conductive film substrates. Is possible.

Claims

An acrylic resin (A) having positive intrinsic birefringence;
A resin (B) having a negative intrinsic birefringence and having a structural unit derived from an N-substituted maleimide monomer,
The content of the structural unit derived from the N-substituted maleimide monomer is 1% by weight or more and 10% by weight or less,
A resin composition having a glass transition temperature (Tg) of 130 ° C. or higher.
The resin composition according to claim 1, wherein a difference in Tg between the acrylic resin (A) and the resin (B) is 20 ° C or less.
2. The resin composition according to claim 1, wherein the absolute value of the stress optical coefficient Cr is 1.0 × 10 −10 Pa −1 or less.
The resin composition according to claim 1, wherein the acrylic resin (A) has a ring structure in the main chain.
The resin composition according to claim 4, wherein the ring structure is at least one selected from a lactone ring structure, a glutarimide structure, a glutaric anhydride structure, a maleic anhydride structure, and an N-substituted maleimide structure.
The ring structure is a ring structure formed by an intramolecular cyclization reaction between two adjacent structural units in the precursor polymer;
The resin composition according to claim 4, wherein a content of the ring structure in the resin composition is 30% by weight or less.
The resin composition according to claim 1, wherein the content of the structural unit derived from the N-substituted maleimide monomer in the resin composition is 5% by weight or less.
The resin composition according to claim 1, wherein the resin (B) further comprises a structural unit derived from an aromatic vinyl monomer.
2. The resin composition according to claim 1, wherein the absolute value of the photoelastic coefficient is 1.0 × 10 −12 Pa −1 or less.
A film comprising the resin composition according to any one of claims 1 to 9.
Stretched film,
The film according to claim 10, wherein an in-plane retardation Re for light having a wavelength of 590 nm is 5 nm or less, and an absolute value of a thickness direction retardation Rth for the light is 5 nm or less.
Stretched film,
The film according to claim 10, which exhibits a folding endurance of 200 times or more in a folding endurance (MIT) test carried out based on JIS P8115.