JP2009162850A - Resin composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a new resin composition for lessening birefringence by shortening wavelength of light and achieving a birefringence member having reverse wavelength dispersion without performing lamination of two kinds of the birefringence members different in a phase difference or wavelength dispersion or addition of particulates having specific optical characteristics. <P>SOLUTION: The resin composition contains a polymer (A) having positive inherent birefringence and having a ring structure in a main ring, and a polymer (B) having negative birefringence regarding α,β-unsaturated monomer unit having a complex aromatic group as a composition unit. The ring structure is, for example, a lactone ring structure, glutarimide structure and anhydrous glutaric acid structure. The unsaturated monomer unit is at least one selected from vinylcarbazole unit, vinylpridine unit, vinylimid azole unit and vinylthiophene unit, for example. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a resin composition used in the production of an optical member, specifically, an optical member having birefringence such as a retardation plate.

  Optical members having birefringence utilizing birefringence caused by polymer orientation are widely used in the field of image display. For example, a phase difference plate using a phase difference caused by birefringence is widely used for color tone compensation and viewing angle compensation of an image display device. As a specific example, in a reflective liquid crystal display device (LCD), a retardation plate (λ / 4 plate) whose optical path length difference (retardation) based on the phase difference caused by birefringence is 1/4 of the wavelength. Is used. For example, in an organic EL display (OLED), an antireflection plate in which a polarizing plate and a λ / 4 plate are combined at a predetermined angle may be used for the purpose of preventing reflection of external light. These optical members having birefringence (hereinafter, also simply referred to as “birefringent members”) are expected to further expand applications in the future.

  Up to now, polycarbonate and cyclic olefin have been mainly used for the birefringent member, but these general polymers have larger birefringence (that is, the phase difference increases) as the wavelength of light becomes shorter. Has characteristics. In order to obtain an image display device having excellent display characteristics, on the contrary, at least in the visible light region, the birefringence becomes smaller (that is, the phase difference is reduced) as the wavelength of light becomes shorter. A birefringent member is desired. In this specification, a wavelength dispersion having a general polymer (and a birefringent member formed of the polymer) has a wavelength dispersibility in which birefringence decreases as the wavelength of light becomes shorter at least in the visible light region. It is called “reverse wavelength dispersibility” based on the opposite of the property.

  Until now, in order to obtain a birefringent member having reverse wavelength dispersion, two types of birefringent members having different phase differences or wavelength dispersion are laminated, or fine particles having specific optical characteristics are added to the member. (For example, see Patent Document 1 for the addition of fine particles). However, in order to realize the reverse wavelength dispersion by laminating two kinds of birefringent members, it is required to cut both members precisely at a predetermined angle and to laminate them precisely at a predetermined angle. As a result, the manufacturing process becomes complicated, resulting in significant problems in cost and productivity of the birefringent member. In addition, image display devices used in mobile devices are highly demanded for miniaturization and weight reduction. However, in a method of realizing reverse wavelength dispersion by laminating two kinds of members, the resulting birefringent member becomes thick. It is difficult to respond to this request. On the other hand, in the method of adding fine particles, the manufacturing process becomes complicated, and significant problems remain in the cost and productivity of the birefringent member.

Apart from these technologies, Patent Document 2 discloses a retardation plate having reverse wavelength dispersion obtained by blending a polymer having positive intrinsic birefringence and a polymer having negative intrinsic birefringence. Has been. In this document, a norbornene resin is exemplified as a polymer having positive intrinsic birefringence, and a styrene polymer is exemplified as a polymer having negative intrinsic birefringence.
JP 2005-156864 A JP 2001-337222 A

  The present invention can realize a birefringent member having reverse wavelength dispersion without laminating two types of birefringent members having different phase differences or wavelength dispersion or adding fine particles having specific optical characteristics. An object is to provide a novel resin composition.

  The resin composition of the present invention comprises a polymer (A) having a positive intrinsic birefringence and a ring structure in the main chain, and an α, β-unsaturation having a negative intrinsic birefringence and a heteroaromatic group. And a polymer (B) having a monomer unit as a constituent unit.

  The intrinsic birefringence is a refractive index n1 of light in a direction parallel to the direction in which the molecular chains are oriented (light distribution axis) in a layer (for example, a sheet or film) in which the molecular chains of the polymer are uniaxially oriented. A value obtained by subtracting the refractive index n2 of light in the direction perpendicular to the light distribution axis (that is, "n1-n2").

  The resin composition of the present invention includes a polymer having a positive intrinsic birefringence (A) and a polymer having a negative intrinsic birefringence (B). For example, by stretching after molding the resin composition, If orientation is applied to both polymers in the same direction, the slow axes (or fast axes) of the respective polymers are orthogonal to each other, so that the birefringence of each other cancels. At this time, since the degree to which birefringence cancels differs depending on the wavelength, a birefringent member having reverse wavelength dispersion can be formed. That is, according to the resin composition of the present invention, the reverse wavelength dispersibility can be achieved without laminating two kinds of birefringent members having different phase differences or wavelength dispersibility or adding fine particles having specific optical characteristics. The birefringent member which has is realizable.

  In the resin composition of the present invention, the polymer (B) having a negative intrinsic birefringence has an α, β-unsaturated monomer unit having a heteroaromatic group in the main chain. The birefringence wavelength dispersion of such a polymer (B) is considerably larger than that of the polymer (A) having a positive intrinsic birefringence and having a ring structure in the main chain. In the resin composition of the present invention, as described above, the polymers (A) and (B) having greatly different birefringence wavelength dispersibility are combined, and the control of the reverse wavelength dispersibility when the birefringent member is obtained. The degree of freedom can be improved.

[Polymer (A)]
The polymer (A) is not particularly limited as long as it has a positive intrinsic birefringence and a polymer having a ring structure in the main chain.

  Examples of the ring structure of the polymer (A) include a ring structure having an ester group, an imide group, or an acid anhydride group.

  More specific examples of the ring structure include a lactone ring structure, a glutarimide structure, or a glutaric anhydride structure. Since the polymer (A) having such a ring structure in the main chain exhibits a large positive intrinsic birefringence depending on the orientation, when a birefringent member is formed by using a resin composition combined with the polymer (B). The degree of freedom in controlling the reverse wavelength dispersion can be further improved, and a birefringent member having good reverse wavelength dispersion according to the application can be realized.

  The ring structure of the polymer (A) is preferably a lactone ring structure or a glutarimide structure, and more preferably a lactone ring structure. The polymer (A) having such a ring structure in the main chain exhibits a large positive intrinsic birefringence depending on the orientation as described above, and further has a feature that the wavelength dispersion is very small. Therefore, a birefringent member can be obtained by combining a polymer (A) having a lactone ring structure or a glutarimide structure, preferably a lactone ring structure, and the polymer (B) in the main chain. In this case, the degree of freedom in controlling the reverse wavelength dispersion can be further improved.

  Although the specific lactone ring structure which the polymer (A) may have is not specifically limited, For example, the structure shown by the following formula | equation (1) may be sufficient.

In the above formula (1), R ¹ , R ² and R ³ 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; in the alkyl group, the unsaturated aliphatic hydrocarbon group, and the aromatic hydrocarbon group, One or more is a group substituted by at least one group selected from a hydroxyl group, a carboxyl group, an ether group and an ester group.

The lactone ring structure represented by the formula (1) is obtained by copolymerizing a monomer group including, for example, methyl methacrylate (MMA) and 2- (hydroxymethyl) methyl acrylate (MHMA), Adjacent MMA units and MHMA units in the coalescence can be formed by dealcoholization cyclocondensation. At this time, R ¹ is H, R ² is CH ₃ , and R ³ is CH ₃ .

  The glutarimide structure that the polymer (A) may have is a ring structure represented by the following formula (2). The glutarimide structure can be formed, for example, by polymerizing a monomer group containing (meth) acrylic acid ester and imidizing the obtained polymer with an imidizing agent such as methylamine.

In the above formula (2), R ⁴ , R ⁵ and R ⁶ are each independently a hydrogen atom or a group exemplified as the organic residue in the formula (1).

  The glutaric anhydride structure that the polymer (A) may have is a ring structure represented by the following formula (3). The glutaric anhydride structure is obtained by, for example, copolymerizing a monomer group containing (meth) acrylic acid ester and (meth) acrylic acid, and then subjecting the obtained copolymer to dealcoholization cyclocondensation in the molecule. Can be formed.

In the above formula (3), R ⁷ and R ⁸ are each independently a group exemplified as a hydrogen atom or an organic residue in formula (1).

  The polymer (A) is preferably a (meth) acrylic resin containing the above-mentioned ring structure which is a (meth) acrylic acid ester unit and a derivative thereof as a structural unit. By setting it as the resin composition containing such a polymer (A), the birefringent member excellent in various characteristics, such as transparency, mechanical strength, and moldability, is realizable. The total of the proportion of the (meth) acrylic acid ester unit and the proportion of the ring structure which is a derivative thereof in all the structural units of the (meth) acrylic resin is usually 50% or more, preferably 60% or more, More preferably, it is 70% or more.

  In each method for forming a lactone ring structure, a glutarimide structure, and a glutaric anhydride structure exemplified in the description of formulas (1) to (3), all the polymers used for forming each ring structure are (meta ) Since it contains an acrylic ester unit, a polymer (A) of a (meth) acrylic resin can be obtained.

  The polymer (A) may contain any structural unit as long as it has positive intrinsic birefringence and a ring structure in the main chain. For example, the polymer (A) which is a (meth) acrylic resin includes a (meth) acrylic acid ester unit (for example, the above-described MMA unit or MHMA unit). For example, since compatibility with the polymer (B) can be improved, the polymer (A) may contain an α, β-unsaturated monomer unit having a heteroaromatic group. Specific examples of the α, β-unsaturated monomer unit will be described later in the description of the polymer (B), and are, for example, a vinylcarbazole unit.

  The polymer (A) can be produced by a known method.

  The polymer (A) having a lactone ring structure as a ring structure is prepared by, for example, heating a polymer (a) having a hydroxyl group and an ester group in the molecular chain in the presence of an arbitrary catalyst, and lactone cyclization accompanied by dealcoholization. It can be obtained by advancing the condensation reaction. Specifically, the polymer (A) can be produced by the method described in JP-A No. 2001-151814.

  The polymer (a) can be formed, for example, by polymerization of a monomer group including a monomer represented by the following formula (4).

In the above formula (4), R ⁹ and R ¹⁰ are each independently a hydrogen atom or a group similar to the organic residue in the formula (1).

  Specific examples of the monomer represented by the formula (4) include methyl 2- (hydroxymethyl) acrylate, ethyl 2- (hydroxymethyl) acrylate, isopropyl 2- (hydroxymethyl) acrylate, 2- (Hydroxymethyl) normal butyl acrylate, 2- (hydroxymethyl) acrylate t-butyl and the like. Among these, 2- (hydroxymethyl) methyl acrylate and 2- (hydroxymethyl) ethyl acrylate are preferable, and since a birefringent member having high transparency and heat resistance can be realized, 2- (hydroxymethyl) methyl acrylate (MHMA) is particularly preferred.

  The monomer group used for forming the polymer (a) may contain two or more monomers represented by the above formula (4).

  The monomer group used for forming the polymer (a) may contain a monomer other than the monomer represented by the above formula (4). Such a monomer is not particularly limited as long as it is a monomer that can be copolymerized with the monomer represented by the formula (4), and may be, for example, a (meth) acrylic acid ester.

  Here, the (meth) acrylic acid ester is a monomer other than the monomer represented by the formula (4), for example, methyl acrylate, ethyl acrylate, n-butyl acrylate, isobutyl acrylate. Acrylates such as t-butyl acrylate, cyclohexyl acrylate, benzyl acrylate; methyl methacrylate, ethyl methacrylate, propyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, t-butyl methacrylate, methacrylic acid And methacrylic acid esters such as cyclohexyl and benzyl methacrylate; Among these, methyl methacrylate (MMA) is particularly preferable because a birefringent member having high transparency and heat resistance can be realized.

  The monomer group used for forming the polymer (a) may contain two or more of these (meth) acrylic acid esters.

  As long as the polymer (A) obtained by subjecting the polymer (a) to a cyclization condensation reaction has a positive intrinsic birefringence, the monomer group used for forming the polymer (a) has a heteroaromatic group. An α, β-unsaturated monomer having, for example, vinyl carbazole represented by the following formula (5) may be included. In this case, a polymer (A) containing an α, β-unsaturated monomer unit having a heteroaromatic group (for example, a vinyl carbazole unit) as a constituent unit can be obtained, and compatibility with the polymer (B). Can be improved.

  In addition, a part of hydrogen atoms on the ring shown in Formula (5) may be substituted with the group exemplified as the organic residue in Formula (1).

  The monomer group used for forming the polymer (a) is one or two other monomers such as styrene, vinyl toluene, α-methyl styrene, acrylonitrile, methyl vinyl ketone, ethylene, propylene, and vinyl acetate. More than one species may be included.

  Since the polymer (A) has a ring structure in the main chain, the resin composition of the present invention can form a birefringent member having excellent heat resistance.

[Polymer (B)]
The polymer (B) is not particularly limited as long as it has an α, β-unsaturated monomer unit having a negative intrinsic birefringence and a heteroaromatic group as a constituent unit. The unsaturated monomer unit having a heteroaromatic group has an effect of greatly increasing the wavelength dispersibility of the polymer (B) containing the unit in the main chain. Therefore, the polymer (A), particularly a polymer (A) having a lactone ring structure or a glutarimide structure as a ring structure (as described above, a polymer (A) having a lactone ring structure or a glutarimide structure, In combination with the polymer (A) having a lactone ring structure, the wavelength dispersion is very small), the degree of freedom in controlling the reverse wavelength dispersion when a birefringent member is formed can be further improved.

  In the combination of resins disclosed in Patent Document 2 (Japanese Patent Laid-Open No. 2001-337222), the difference in wavelength dispersion between the two is not so large, so the polymers (A) and (B) were combined. You can't get the same effect.

  In addition, since the unsaturated monomer unit has a function of greatly increasing the wavelength dispersibility of the polymer (B), the proportion of the unsaturated monomer unit in all the structural units of the polymer (B) is Even when the polymer is low, the polymer (B) exhibits a large wavelength dispersion (see the results of Comparative Example 3 of the present application [Table 6]. Incidentally, resins used for conventional optical members such as polycarbonate and polystyrene are Even in the case of a homopolymer, only the wavelength dispersion within the range of about 0.95 to 1.15 is shown as the R / R0 value in the visible light region shown in the examples of the present application). On the other hand, since an aromatic ring usually has an action of increasing the photoelastic coefficient of a polymer containing the ring, when the resin composition for an optical member is used, the content of the aromatic ring in the composition is suppressed. Is desired. In the resin composition of the present invention, since the polymer (B) showing a large wavelength dispersibility even when the ratio of the unsaturated monomer unit is low, the aromatic ring content in the resin composition is reduced. It is possible to reduce the increase of the photoelastic coefficient when the birefringent member is used.

  The kind of the unsaturated monomer unit is not particularly limited. The hetero atom in the heteroaromatic group is, for example, an oxygen atom, a sulfur atom, or a nitrogen atom, and a nitrogen atom is preferable because of excellent action of increasing the wavelength dispersibility of the polymer (B).

  A specific type of the unsaturated monomer unit is, for example, at least one selected from a vinyl carbazole unit, a vinyl pyridine unit, a vinyl imidazole unit, and a vinyl thiophene unit.

  The unsaturated monomer unit is preferably at least one selected from a vinyl carbazole unit and a vinyl pyridine unit, since it is particularly excellent in the action of increasing the wavelength dispersibility of the polymer (B). Is more preferable.

  The vinyl carbazole unit is a structural unit represented by the following formula (6). In addition, a part of hydrogen atom on the ring shown in Formula (6) may be substituted by the group exemplified as the organic residue in Formula (1).

  The specific configuration of the polymer (B) is not particularly limited as long as it has an intrinsic α, β-unsaturated monomer unit having a negative intrinsic birefringence and a heteroaromatic group. The copolymer of a monomer and another monomer may be sufficient.

  More specifically, the polymer (B) is a copolymer of the unsaturated monomer and the (meth) acrylate ester, that is, a resin containing a (meth) acrylate ester unit as a constituent unit. Also good. In this case, when the polymer (A) is a (meth) acrylic resin, the compatibility between the polymer (A) and the polymer (B) can be improved. Examples of such a polymer (B) include a copolymer of vinyl carbazole and (meth) acrylic acid ester.

  For example, the polymer (B) may have a ring structure similar to the ring structure of the polymer (A) in the main chain. In this case, a birefringent member having better heat resistance can be formed.

  The polymer (B) can be produced by a known method.

[Resin composition]
The mixing ratio of the polymer (A) and the polymer (B) in the resin composition of the present invention is the absolute value of the intrinsic birefringence of each polymer or the reverse wavelength dispersion required when a birefringent member is used. It can be adjusted according to the degree of sex. For example, when a resin composition having positive intrinsic birefringence is used, the polymers (A) and (B) may be mixed within a range in which the intrinsic birefringence of the resin composition is positive.

  When attention is paid to the content X1 (% by weight) of the ring structure contained in the entire resin composition and the content X2 (% by weight) of the α, β-unsaturated monomer unit having a heteroaromatic group, X1 and The ratio to X2 is, for example, in the range of X1: X2 = 99.5: 0.5 to 70:30, preferably in the range of X1: X2 = 95: 5 to 75:25, and X1: X2 = 95: A range of 5 to 80:20 is more preferable. Within this range, the degree of freedom in controlling the reverse wavelength dispersion when used as a birefringent member can be further improved, and a birefringent member having good reverse wavelength dispersion according to the application can be formed.

The ring structure content X1 can be evaluated by the method described in JP-A No. 2001-151814. The content X2 of the unsaturated monomer units including the vinylcarbazole unit can be determined by a known method, for example, ¹ H nuclear magnetic resonance ( ¹ H-NMR) or infrared spectroscopic analysis (IR).

  The resin composition of the present invention can be obtained, for example, by dissolving the polymers (A) and (B) in a solvent that dissolves both polymers. The solution in which the polymers (A) and (B) are dissolved may be circulated as it is, or may be circulated as a solid resin composition by volatilizing the solvent.

  The resin composition of the present invention may contain a polymer other than the polymers (A) and (B), or other various materials, as long as the effect of the present invention is obtained. As such a material, for example, when the compatibilizing agent for improving the compatibility of the polymers (A) and (B) or the polymers (A) and (B) is used as a solution, the stability of the solution is increased. And stabilizers that improve the properties.

[Birefringent member]
For example, a birefringent member can be formed from the resin composition of the present invention. In this case, it can be said that the resin composition of the present invention is a resin composition for a birefringent member.

  The birefringent member (birefringent member of the present invention) formed from the resin composition of the present invention has reverse wavelength dispersion. That is, the birefringent member has a birefringence characteristic that birefringence (or phase difference or retardation) decreases as the wavelength becomes shorter, at least in the visible light region. Such a birefringent member is a broadband birefringent member. For example, by using this birefringent member, an image display device having excellent display characteristics can be constructed.

  In addition, the birefringent member of the present invention exhibits, for example, reverse wavelength dispersion while being a single layer. Therefore, the birefringent member is excellent in productivity and cost, and the image display device incorporating the birefringent member can be reduced in size, weight, and cost.

  The specific shape of the birefringent member of the present invention is not particularly limited. What is necessary is just to select suitably according to the use as a birefringent member, for example, it is good also as a sheet | seat or a film.

  The birefringent member of the present invention may be used in combination with another optical member (the optical member includes a birefringent member) depending on the application.

  The specific type of the birefringent member of the present invention is not particularly limited, and may be, for example, a retardation plate, or a retardation plate based on the retardation based on the obtained retardation, which is 1/4 of the wavelength of light. A λ / 4 plate may be used. Moreover, it can also be set as an antireflection plate combining with other optical members, such as a polarizing plate.

  The use of the birefringent member of the present invention is not particularly limited, and the birefringent member of the present invention can be used for the same use as a conventional birefringent member (for example, an image display device such as an LCD or an OLED).

  The polymer (A) contained in the resin composition of the present invention has a ring structure in its main chain. For this reason, the birefringent member of the present invention has high heat resistance, and can be disposed close to a heat generating part such as a light source in an image display device, for example.

  The method for forming the birefringent member from the resin composition of the present invention is not particularly limited, and a known technique may be followed. When the resin composition of the present invention is in the form of a solution, for example, the solution is molded into a sheet by a technique such as casting, and the obtained sheet is stretched in a predetermined direction, typically uniaxially stretched or sequentially biaxially. A sheet-like birefringent member can be formed by stretching and orienting the molecular chains of both polymers contained in the sheet. If it is a solid resin composition, for example, the resin composition is formed into a sheet or film by a molding technique such as melt extrusion or press molding, and the obtained sheet (film) is stretched in a predetermined direction as described above, A sheet-like (film-like) birefringent member can be formed.

  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.

(Production Example 1)
In a reactor equipped with a stirrer, temperature sensor, condenser, and nitrogen inlet, 15 parts by weight of methyl 2- (hydroxymethyl) acrylate (MHMA), 35 parts by weight of methyl methacrylate (MMA), and polymerization 50 parts by weight of toluene was charged as a solvent, and the temperature was raised to 105 ° C. while passing nitrogen through the solvent. At the start of reflux accompanying the temperature rise, 0.03 parts by weight of t-amyl peroxyisononanoate (manufactured by Arkema Yoshitomi Co., Ltd., trade name: Luperox 570) was added as a polymerization initiator and 3.34 parts by weight. While a solution of 0.06 part by weight of the above t-amylperoxyisononanoate dissolved in toluene was added dropwise over 2 hours, solution polymerization was allowed to proceed under reflux at about 105 to 110 ° C., and further aged for 4 hours. Went.

  Next, 0.1 parts by weight of an octyl phosphate / dioctyl mixture is added to the resulting polymerization solution as a catalyst for the cyclization condensation reaction (cyclization catalyst), and the mixture is refluxed at about 80 to 105 ° C. for 2 hours. The cyclization condensation reaction proceeded.

  Next, the polymerization solution thus obtained was dried at 240 ° C. under reduced pressure for 1 hour to form a transparent polymer (A-1) having a lactone ring structure in the main chain.

(Production Example 2)
A reactor equipped with a stirrer, a temperature sensor, a cooling pipe, and a nitrogen introduction pipe was charged with 15 parts by weight of MHMA, 25 parts by weight of MMA, 10 parts by weight of benzyl methacrylate, and 50 parts by weight of toluene as a polymerization solvent. The mixture was charged and heated to 105 ° C. while passing nitrogen through it. At the start of reflux accompanying the temperature rise, 0.03 parts by weight of t-amyl peroxyisononanoate (manufactured by Arkema Yoshitomi Co., Ltd., trade name: Luperox 570) was added as a polymerization initiator and 3.34 parts by weight. While the solution of 0.06 part by weight of t-amylperoxyisononanoate dissolved in toluene was added dropwise over 6 hours, solution polymerization was allowed to proceed under reflux at about 105 to 111 ° C., and the aging was continued for 2 hours. Went.

  Next, 0.1 part by weight of an octyl phosphate / dioctyl mixture was added to the resulting polymerization solution as a cyclization catalyst, and the cyclization condensation reaction was allowed to proceed for 2 hours under reflux at about 80 to 105 ° C. .

  Next, the polymerization solution thus obtained was dried at 240 ° C. under reduced pressure for 1 hour to form a transparent polymer (A-2) having a lactone ring structure in the main chain.

  The intrinsic birefringence of the formed polymer (A-2), the orientation angle of the polymer (A-2) formed into a stretched film by the method described in Example 1, is determined by a fully automatic birefringence meter (manufactured by Oji Scientific Instruments, It was positive when evaluated by measuring using KOBRA-21ADH).

(Production Example 3)
A reactor equipped with a stirrer, a temperature sensor, a cooling tube, and a nitrogen introduction tube was charged with 10 parts by weight of vinylcarbazole, 18 parts by weight of MHMA, 72 parts by weight of MMA, and 80 parts by weight of toluene as a polymerization solvent. The temperature was raised to 105 ° C. while nitrogen was passed through. When the reflux with the temperature increase started, 0.1 parts by weight of t-amyl peroxyisononanoate (manufactured by Arkema Yoshitomi, trade name: Luperox 570) was added as a polymerization initiator and 10 parts by weight of toluene. While a solution in which 0.2 parts by weight of t-amylperoxyisononanoate was dissolved in 2 hours was added dropwise over 2 hours, solution polymerization was allowed to proceed under reflux at about 105 to 110 ° C., followed by aging for 4 hours. It was.

  Next, 0.9 parts by weight of an octyl phosphate / dioctyl mixture dissolved in 10 parts by weight of toluene was added to the obtained polymerization solution, and MHMA units in the polymer formed by the above polymerization for 2 hours under reflux. A cyclocondensation reaction was allowed to proceed between the MMA unit and the MMA unit.

  Next, the polymerization solution thus obtained was dried at 240 ° C. under reduced pressure for 1 hour to form a transparent polymer (B-1) having vinylcarbazole units in the main chain. In addition, although the obtained polymer (B-1) has a lactone ring structure in the main chain, this ring structure is composed of the polymer (B-1) and the polymer (A-1) or (A- It was formed for the purpose of improving the compatibility with 2).

Example 1
10 parts by weight of the polymer (A-1) produced in Production Example 1 as the polymer (A) and 20 parts by weight of the polymer (B-1) produced in Production Example 3 as the polymer (B) The polymer (A-1) and (B-1) were uniformly mixed by dissolving in isobutyl ketone and stirring the resulting solution. Next, the obtained mixed solution was dried at 240 ° C. under reduced pressure for 1 hour to obtain 30 parts by weight of a solid resin composition.

  Next, the obtained resin composition was press-molded at 250 ° C. with a press molding machine to obtain a film having a thickness of 100 μm. Next, the produced film was uniaxially stretched at a stretching temperature of 138 ° C. by a biaxial stretching device (TYPE EX4, manufactured by Toyo Seiki Seisakusho Co., Ltd.) so that the stretching ratio in the MD direction was doubled, and the thickness was 40 μm. A stretched film was obtained.

  The wavelength dispersibility and the orientation angle of retardation (in-plane retardation) of the obtained stretched film were evaluated using a fully automatic birefringence meter (manufactured by Oji Scientific Instruments, KOBRA-21ADH). The evaluation results of wavelength dispersion are shown in Table 1 below. The phase difference when the measurement wavelength is 589 nm is used as a reference (R0), and the ratio (R / R0) to the phase difference R at other wavelengths is also shown.

  As shown in Table 1, the stretched film obtained in Example 1 exhibited reverse wavelength dispersibility in which the phase difference decreased as the wavelength of light decreased.

  The orientation angle (φ) of the stretched film obtained in Example 1 was −0.8 °, that is, its intrinsic birefringence was positive.

(Example 2)
As the polymer (A), a stretched film was produced in the same manner as in Example 1 except that the polymer (A-2) produced in Production Example 2 was used instead of the polymer (A-1). The wavelength dispersion of the retardation and the orientation angle of the produced stretched film were evaluated in the same manner as in Example 1. The evaluation results of wavelength dispersion are shown in Table 2 below.

  As shown in Table 2, the stretched film obtained in Example 2 exhibited reverse wavelength dispersibility in which the phase difference decreased as the wavelength of light decreased.

  The orientation angle (φ) of the stretched film obtained in Example 2 was 0.6 °, that is, its intrinsic birefringence was positive.

(Example 3)
10 parts by weight of an acrylic imide resin (Rohm and Haas, KAMAX T-240) as the polymer (A) and 25 parts by weight of the polymer (B-1) formed in Production Example 3 as the polymer (B) Except that it was used, 35 parts by weight of a solid resin composition was obtained in the same manner as in Example 1. The acrylic imide resin used as the polymer (A) has an N-methyl-dimethylglutarimide unit and a methyl methacrylate unit as its constituent units, as shown in the following formula (7).

  Next, the obtained resin composition was press-molded at 250 ° C. with a press molding machine to obtain a film having a thickness of 100 μm. Next, the produced film was uniaxially stretched at a stretching temperature of 143 ° C. by a biaxial stretching apparatus (TYPE EX4, manufactured by Toyo Seiki Seisakusho Co., Ltd.) so that the stretching ratio in the MD direction was doubled, and the thickness was 50 μm. A stretched film was obtained.

  Next, the wavelength dispersion of the retardation and the orientation angle of the obtained stretched film were evaluated in the same manner as in Example 1. The evaluation results of wavelength dispersion are shown in Table 3 below.

  As shown in Table 3, the stretched film obtained in Example 3 exhibited reverse wavelength dispersibility in which the phase difference decreased as the wavelength of light decreased.

  The orientation angle (φ) of the stretched film obtained in Example 3 was −2.1 °, that is, its intrinsic birefringence was positive.

(Comparative Example 1)
By using only the polymer (A-1) formed in Production Example 1 and performing press molding and uniaxial stretching in the same manner as in Example 1, a stretched film (thickness 40 μm) of the polymer (A-1) is obtained. Obtained. The wavelength dispersion of the retardation and the orientation angle of the obtained stretched film were evaluated in the same manner as in Example 1. The evaluation results of wavelength dispersion are shown in Table 4 below.

  As shown in Table 4, the stretched film obtained in Comparative Example 1 has a larger retardation as the wavelength of light is shorter, that is, similar to a birefringent member using a general polymer such as polycarbonate, It showed wavelength dispersion.

  The orientation angle (φ) of the stretched film obtained in Comparative Example 1 was −0.7 °, that is, its intrinsic birefringence was positive.

(Comparative Example 2)
A stretched film having a thickness of 50 μm was obtained by performing press molding and uniaxial stretching in the same manner as in Example 1 using only the acrylic imide resin used in Example 3. The wavelength dispersion of the retardation and the orientation angle of the obtained stretched film were evaluated in the same manner as in Example 1. The evaluation results of wavelength dispersion are shown in Table 5 below.

  As shown in Table 5, the stretched film obtained in Comparative Example 2 has a larger retardation as the wavelength of light becomes shorter, that is, similar to a birefringent member using a general polymer such as polycarbonate, It showed wavelength dispersion.

  The orientation angle (φ) of the stretched film obtained in Comparative Example 2 was −0.8 °, that is, its intrinsic birefringence was positive.

(Comparative Example 3)
By using only the polymer (B-1) formed in Production Example 3, press forming and uniaxial stretching were performed in the same manner as in Example 1 to obtain a stretched film of the polymer (B-1). The wavelength dispersion of the retardation and the orientation angle of the obtained stretched film were evaluated in the same manner as in Example 1. The evaluation results of wavelength dispersion are shown in Table 6 below.

  As shown in Table 6, the stretched film obtained in Comparative Example 3 has a larger retardation as the wavelength of light is shorter, that is, similar to a birefringent member using a general polymer such as polycarbonate, It showed wavelength dispersion.

  The orientation angle (φ) of the stretched film obtained in Comparative Example 3 was 89.4 °, that is, its intrinsic birefringence was negative.

  According to the resin composition of the present invention, a compound having reverse wavelength dispersion can be obtained without laminating two kinds of birefringent members having different phase differences or wavelength dispersion or adding fine particles having specific optical characteristics. A refractive member can be realized. Moreover, according to the resin composition of this invention, the freedom degree of control of reverse wavelength dispersion when it is set as a birefringent member can be improved.

  The birefringent member formed from the resin composition of the present invention can be widely used in image display devices such as liquid crystal display devices (LCD) and organic EL displays (OLEDs), as with conventional birefringent members. By using the refractive member, the image display device can be reduced in size and weight.

Claims (10)

A polymer (A) having a positive intrinsic birefringence and a ring structure in the main chain;
A resin composition comprising: a polymer (B) having a negative intrinsic birefringence and having an α, β-unsaturated monomer unit having a heteroaromatic group as a constituent unit.   The resin composition according to claim 1, wherein the α, β-unsaturated monomer unit is at least one selected from a vinylcarbazole unit, a vinylpyridine unit, a vinylimidazole unit, and a vinylthiophene unit.   The resin composition according to claim 1, wherein the α, β-unsaturated monomer unit is a vinyl carbazole unit.   The resin composition according to claim 1, wherein the ring structure has an ester group, an imide group, or an acid anhydride group.   The resin composition according to claim 1, wherein the ring structure is a lactone ring structure, a glutarimide structure, or a glutaric anhydride structure.   The resin composition according to claim 1, wherein the ring structure is a lactone ring structure or a glutarimide structure.   The resin composition according to claim 1, wherein the ring structure is a lactone ring structure. The resin composition according to claim 7, wherein the ring structure is a lactone ring structure represented by the following formula (1).

In the above formula (1), R ¹ , R ² and R ³ are each independently a hydrogen atom or an organic residue having 1 to 20 carbon atoms, and the organic residue contains an oxygen atom. Also good.   The resin composition according to any one of claims 1 to 8, wherein the polymer (A) is a (meth) acrylic resin.   The resin composition according to claim 9, wherein the polymer (B) has a (meth) acrylic acid ester unit as a structural unit.