JP5350640B2 - Thermoplastic resin composition, resin molded product and polarizer protective film using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a thermoplastic resin composition comprising a heat-resistant acrylic resin and an ultraviolet light absorber (UVA), which is a composition for controlling the occurrence of defects such as bleed-out etc., during and after molding. <P>SOLUTION: The thermoplastic resin composition comprises a thermoplastic resin comprising an acrylic resin as a main component and a benzotriazole-based ultraviolet light absorber liquid at 25&deg;C and has a glass transition temperature of &ge;110&deg;C. The acrylic resin preferably has a ring structure in a main chain and the ring structure is, for example, a lactone ring structure. <P>COPYRIGHT: (C)2009,JPO&amp;INPIT

Description

  The present invention relates to a thermoplastic resin composition suitable as a heat-resistant transparent material, a resin molded product comprising the composition, and a polarizer protective film as a specific example of the resin molded product. Moreover, this invention relates to a polarizing plate provided with the said protective film, and an image display apparatus provided with the said polarizing plate.

  An acrylic resin typified by polymethyl methacrylate (PMMA) has excellent optical properties such as high light transmittance, and is excellent in the balance of mechanical strength, molding processability and surface hardness. Widely used as a transparent material in various industrial products such as home appliances. In recent years, the use of optical members such as optical members used in image display devices has increased.

  When an acrylic resin is exposed to light containing ultraviolet rays, it may turn yellow and the transparency may be lowered. As a method for preventing this, a method of adding an ultraviolet absorber (UVA) is known. However, the molecular weight of UVA is generally small, and foaming may occur or UVA may bleed out when a resin composition containing an acrylic resin and UVA is molded. Further, in this method, UVA evaporates due to heat applied at the time of molding, which may cause problems such as a decrease in ultraviolet absorption ability of the obtained molded product or contamination of the molding apparatus by UVA.

  On the other hand, resins having a ring structure in the main chain are known as acrylic resins having both transparency and heat resistance. A resin having a ring structure in the main chain has a higher glass transition temperature (Tg) than a resin having no ring structure in the main chain. For example, it is easy to dispose a resin near a heat generating part such as a light source in an image display device. It has various practical advantages such as. For example, Patent Documents 1 and 2 disclose acrylic resins having a lactone ring structure in the main chain obtained by cyclization condensation reaction of a polymer having a hydroxyl group and an ester group in the molecular chain. Patent Document 3 discloses an acrylic resin having an N-substituted maleimide structure as a ring structure in the main chain. Patent Document 4 discloses an acrylic resin having a glutarimide structure as a ring structure in the main chain.

  However, these acrylic resins having heat resistance need to have a higher molding temperature than general acrylic resins. For this reason, when UVA is added to heat-resistant acrylic resin, defects such as foaming or bleed-out are likely to occur in the obtained molded product, and UVA absorption ability is increased due to strong transpiration of UVA during molding. Decrease and contamination of the molding apparatus are likely to occur.

  Considering these problems, triazine compounds, benzotriazole compounds, or benzophenone compounds, which are considered to have a high ultraviolet absorption effect with a small amount of addition, have been used in combination with acrylic resins as UVA. Yes. For example, Patent Document 4 described above also discloses the above compound.

However, these compounds have problems in compatibility with acrylic resins having heat resistance. Further, when forming an optical member from a resin composition containing an acrylic resin and UVA, the composition is filtered through a polymer filter or the like in order to reduce defects in appearance of the obtained member. It is desirable to remove foreign substances present in the interior in advance, but for this purpose, it is necessary to further increase the molding temperature of the composition. When the molding temperature is further increased, the occurrence of foaming or the degree of contamination of the molding apparatus is increased. Therefore, further improvement of the above problem is desired. On the other hand, when a resin composition containing an acrylic resin and UVA is used as an optical member, particularly as a film, UVA gradually bleeds out after film formation, and the light reduction rate of the film decreases or turbidity ( It tends to cause quality deterioration such as an increase in haze. When the light beam reduction rate of the film decreases or the turbidity increases, it becomes difficult to use the film as an optical member.
JP 2000-230016 A JP 2006-96960 A JP 2007-31537 A JP 2006-328334 A

  Therefore, the present invention provides a thermoplastic resin composition containing an acrylic resin having heat resistance and UVA, and the resin composition in which the occurrence of defects such as bleed-out during and after molding is suppressed is provided. For the purpose.

  The thermoplastic resin composition of the present invention comprises a thermoplastic resin mainly composed of an acrylic resin (resin (A)) and a benzotriazole ultraviolet absorber (UVA (B)) that is liquid at 25 ° C. The glass transition temperature (Tg) is 110 ° C. or higher.

  The resin molded product of the present invention comprises the resin composition of the present invention. The resin molded product of the present invention is, for example, a film or a sheet.

  The polarizer protective film of this invention is 1 type of the resin molded product of this invention, and consists of the resin composition of the said invention.

  The polarizing plate of the present invention includes a polarizer and the polarizer protective film of the present invention.

  The image display device of the present invention includes the polarizing plate of the present invention.

  In the resin composition of the present invention, a thermoplastic resin mainly composed of an acrylic resin (A) and a benzotriazole-based UVA (B) that is liquid at 25 ° C. are combined, and at the time of molding and after molding. Occurrence of defects such as bleed out can be suppressed. That is, the resin composition of the present invention has a high ultraviolet-absorbing ability, has few defects such as bleed-out, and further suppresses a decrease in light transmittance and an increase in turbidity during actual use. Product can be manufactured. The benzotriazole-based ultraviolet absorber means a compound containing a benzotriazole skeleton as a chromophore for absorbing ultraviolet rays.

  Further, the resin (A) that is the main component of the thermoplastic resin contained in the composition of the present invention is an acrylic resin, the compatibility between the resin (A) and UVA (B) is high, and Since the glass transition temperature as a composition is 110 degreeC or more, the resin molded product which is excellent in heat resistance and transparency can be manufactured with the resin composition of this invention.

[Resin composition]
Hereinafter, the resin composition of the present invention will be described in detail.

[Resin (A)]
The resin (A) is an acrylic resin, and the type thereof is not particularly limited. Here, the acrylic resin is a resin having a (meth) acrylic acid ester unit and / or a (meth) acrylic acid unit as a structural unit. The total ratio of the (meth) acrylic acid ester unit and the (meth) acrylic acid unit in all the structural units of the acrylic resin is usually 50% or more, preferably 60% or more, more preferably 70% or more. is there.

  In addition, Tg in this specification shall be the value calculated | required by the starting point method using the differential scanning calorimeter (DSC) based on prescription | regulation of JISK7121.

  Examples of the (meth) acrylic acid ester unit include methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, n-butyl (meth) acrylate, and (meth) acrylic acid t. -Butyl, n-hexyl (meth) acrylate, cyclohexyl (meth) acrylate, benzyl (meth) acrylate, chloromethyl (meth) acrylate, 2-chloroethyl (meth) acrylate, (meth) acrylic acid 2- Hydroxyethyl, 3-hydroxypropyl (meth) acrylate, 2,3,4,5,6-pentahydroxyhexyl (meth) acrylate, 2,3,4,5-tetrahydroxypentyl (meth) acrylate, 2 Structures derived from monomers such as methyl (hydroxymethyl) acrylate and methyl 2- (hydroxyethyl) acrylate Unit, and the like. Resin (A) may have two or more of these structural units as a (meth) acrylic acid ester unit. The resin (A) preferably has a methyl (meth) acrylate unit. In this case, the thermal stability of the resin (A) (and the resin composition and a resin molded product obtained by molding the composition) is high. improves.

  The resin (A) preferably has a ring structure in the main chain. In this case, Tg of resin (A) improves and it becomes easy to make Tg of a resin composition 110 degreeC or more. Depending on the type of the ring structure and the content of the ring structure in the resin (A), the Tg of the resin composition can be 120 ° C. or higher, and further 130 ° C. or higher. Moreover, when resin (A) has a ring structure in a principal chain, the heat resistance of the molded product obtained by shape | molding the said composition improves.

  The type of the ring structure is not particularly limited. For example, the resin (A) includes at least one ring selected from a glutarimide structure, a glutaric anhydride structure, a maleic anhydride structure, an N-substituted maleimide structure, and a lactone ring structure. You may have a structure in a principal chain.

  Since the effect of improving the Tg of the resin (A) is great, the resin (A) may have at least one ring structure selected from a glutarimide structure, a glutaric anhydride structure, and a lactone ring structure in the main chain. preferable.

  Especially, since the resin composition and resin molded product which are excellent in an optical characteristic are obtained, it is especially preferable that resin (A) has a lactone ring structure in a principal chain.

  The following formula (3) shows a glutarimide structure and a glutaric anhydride structure.

In the above formula (3), R ⁷ and R ⁸ 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 ⁹ does not exist, and when X ¹ is a nitrogen atom, R ⁹ is a hydrogen atom, a linear alkyl group having 1 to 6 carbon atoms, a cyclopentyl group, a cyclohexyl group, or a phenyl group. .

When X ¹ is a nitrogen atom, the ring structure represented by the formula (3) is a glutarimide structure. The glutarimide structure can be formed, for example, by imidizing a (meth) acrylic acid ester polymer with an imidizing agent such as methylamine.

When X ¹ is an oxygen atom, the ring structure represented by the formula (3) is a glutaric anhydride structure. The glutaric anhydride structure can be formed, for example, by subjecting a copolymer of (meth) acrylic acid ester and (meth) acrylic acid to dealcoholization cyclocondensation within the molecule.

  The following formula (4) shows an N-substituted maleimide structure and a maleic anhydride structure.

In the above formula (4), R ¹⁰ and R ¹¹ 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 ¹² does not exist, and when X ² is a nitrogen atom, R ¹² is a hydrogen atom, a linear alkyl group having 1 to 6 carbon atoms, a cyclopentyl group, a cyclohexyl group, or a phenyl group. .

When X ² is a nitrogen atom, the ring structure represented by the formula (4) is an N-substituted maleimide structure. The N-substituted maleimide structure can be formed, for example, by copolymerizing an N-substituted maleimide and a (meth) acrylic acid ester.

When X ² is an oxygen atom, the ring structure represented by the formula (4) is a maleic anhydride structure. The maleic anhydride structure can be formed, for example, by copolymerizing maleic anhydride and (meth) acrylic acid ester.

  In each method for forming a ring structure exemplified in the description of formulas (3) and (4), all polymers used for forming each ring structure have (meth) acrylate units as constituent units. Therefore, the resin obtained by each of the above methods is an acrylic resin.

  The lactone ring structure that the resin (A) may have in the main chain is not particularly limited. For example, it may be a 4- to 8-membered ring, but it is excellent in stability as a ring structure. A ring or a 6-membered ring is preferable, and a 6-membered ring is more preferable. The lactone ring structure which is a 6-membered ring includes, for example, the structure disclosed in JP-A No. 2004-168882, but the precursor (the lactone ring structure is converted into the main chain by subjecting the precursor to a cyclization condensation reaction). The polymerization yield of the resin (A) is high, and the resin (A) having a high lactone ring content can be obtained by the cyclocondensation reaction of the precursor. Since the polymer having as a precursor can be used as a precursor, the structure represented by the following formula (2) is preferable.

In the above formula (2), R ⁴ , R ⁵ and R ⁶ 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 in the formula (2) is, for example, an alkyl group having 1 to 20 carbon atoms such as a methyl group, an ethyl group, or a propyl group; and having 1 to 20 carbon atoms such as an ethenyl group or a propenyl group. An unsaturated aliphatic hydrocarbon group; an aromatic hydrocarbon group having 1 to 20 carbon atoms such as a phenyl group or a naphthyl group; the alkyl group, the unsaturated aliphatic hydrocarbon group, or the aromatic hydrocarbon group. A group in which one or more of hydrogen atoms are substituted with at least one group selected from a hydroxyl group, a carboxyl group, an ether group and an ester group;

The lactone ring structure can be formed by dealcoholization cyclocondensation of a precursor having a hydroxyl group and an ester group in the molecular chain. The lactone ring represented by the formula (2) is formed by, for example, forming a copolymer of methyl methacrylate (MMA) and 2- (hydroxymethyl) methyl acrylate (MHMA) and then adjoining MMA in the copolymer. It can be formed by dealcoholization cyclocondensation of units and MHMA units. At this time, R ⁴ is H, R ⁵ is CH ₃ , and R ⁶ is CH ₃ .

  Although the content rate of the ring structure in resin (A) is not specifically limited, Usually, it is 5-90 weight%, and 20-90 weight% is preferable. The content is more preferably 30 to 90% by weight, 35 to 90% by weight, 40 to 80% by weight, and 45 to 75% by weight. When the content is excessively small, heat resistance as a resin composition (and as a resin molded product obtained by molding the composition) is lowered, and solvent resistance and surface hardness are insufficient. There is. On the other hand, when the said content rate becomes large too much, the moldability and handling property of a resin composition will fall.

  When the resin (A) has a lactone ring structure, the content of the lactone ring structure in the resin (A) can be determined by the dynamic TG method as follows. First, a dynamic TG measurement is performed on the resin (A) having a lactone ring structure, a weight reduction rate between 150 ° C. and 300 ° C. is measured, and the obtained value is an actually measured weight reduction rate (X). And 150 ° C. is a temperature at which the hydroxyl group and ester group remaining in the resin (A) start a cyclization condensation reaction, and 300 ° C. is a temperature at which thermal decomposition of the resin (A) starts. Separately, assuming that all the hydroxyl groups contained in the precursor polymer have undergone a dealcoholization reaction to form a lactone ring, the rate of weight loss due to the reaction (ie, dealcoholization of the precursor) The weight reduction rate (assuming that the condensation reaction rate was 100%) was calculated and used as the theoretical weight reduction rate (Y). Specifically, the theoretical weight reduction rate (Y) can be determined from the content of the structural unit having a hydroxyl group involved in the dealcoholization reaction in the precursor. In addition, the composition of the precursor can be derived from the composition of the resin (A) as necessary. Next, the dealcoholization reaction rate of the resin (A) is determined by the formula [1- (actually measured weight reduction rate (X) / theoretical weight reduction rate (Y))] × 100 (%). In the resin (A), it is considered that a lactone ring structure is formed for the determined dealcoholization reaction rate. Therefore, the lactone ring structure in the resin (A) is obtained by multiplying the content of the structural unit having a hydroxyl group involved in the dealcoholization reaction in the precursor by the determined dealcoholization reaction rate and converting it to the weight of the lactone ring structure. The content of can be determined.

  As an example, the dealcoholization reaction rate of the resin (A) produced in Example 1 described later is obtained. The molecular weight of methanol produced by the dealcoholization reaction is 32, and the content of the MHMA unit, which is a constituent unit having a hydroxyl group involved in the dealcoholization reaction, in the precursor (copolymer of MHMA and MMA) is 20% by weight. Since the molecular weight of the MHMA unit in terms of monomer is 116, the theoretical weight reduction rate (Y) of the resin (A) is (32/116) × 20 = 5.52% by weight. On the other hand, since the actual weight reduction rate (X) of the resin (A) was 0.18% by weight, the dealcoholization reaction rate was 96.7% (= (1−0.18 / 5.52) × 100 (%)).

  Next, the content rate of the lactone ring structure in the resin (A) is determined. Since the MHMA unit content in the precursor is 20% by weight, the MHMA unit monomer molecular weight is 116, the dealcoholization reaction rate is 96.7%, and the formula weight of the lactone ring structure is 170, the above resin The content of the lactone ring structure in (A) is 28.3% (= 20 × 0.967 × 170/116).

  The resin (A) contains various analysis methods such as infrared spectroscopy, near-infrared spectroscopy, Raman spectroscopy, nuclear magnetic resonance, pyrolysis gas chromatography, or mass spectrometry. Depending on the type of ring structure to be used, it may be determined by applying as appropriate.

  The resin (A) may have a structural unit other than the (meth) acrylic acid ester unit and the (meth) acrylic acid unit. Examples of such a structural unit include styrene, vinyltoluene, and α-methyl. Styrene, acrylonitrile, methyl vinyl ketone, ethylene, propylene, vinyl acetate, methallyl alcohol, allyl alcohol, 2-hydroxymethyl-1-butene, α-hydroxymethylstyrene, α-hydroxyethylstyrene, 2- (hydroxyethyl) acrylic Examples include structural units derived from monomers such as 2- (hydroxyalkyl) acrylic acid esters such as methyl acid and 2- (hydroxyalkyl) acrylic acid such as 2- (hydroxyethyl) acrylic acid. The resin (A) may have two or more of these structural units.

  Resin (A) may have a structural unit having an effect of giving negative intrinsic birefringence to the resin. In this case, the degree of freedom in controlling the birefringence of the resin composition (and the resin molded product obtained by molding the composition) is improved, and a resin molded product (for example, resin) formed from the resin composition of the present invention. Use of the film as an optical member is expanded.

  Intrinsic birefringence refers to a refractive index n1 of light in a direction parallel to the direction in which molecular chains are oriented (light distribution axis) in a layer (for example, a sheet or film) in which resin molecular chains are uniaxially oriented. A value obtained by subtracting the refractive index n2 of light in a direction perpendicular to the optical axis (that is, "n1-n2"). The sign of the intrinsic birefringence of the resin (A) itself is determined by the balance between the action of the structural unit with respect to the intrinsic birefringence and the action of the other structural unit of the resin (A).

  An example of a structural unit having an effect of giving negative intrinsic birefringence to the resin (A) is a styrene unit.

  The resin (A) may have a structural unit (UVA unit) having ultraviolet absorbing ability. In this case, the ultraviolet absorbing ability of the resin composition (and the resin molded product obtained by molding the composition) is further improved, and depending on the structure of the UVA unit, the compatibility between the resin (A) and the UVA (B). Improves.

  The monomer (C) that is the source of the UVA unit is not particularly limited, and for example, a benzotriazole derivative, a triazine derivative, or a benzophenone derivative into which a polymerizable group is introduced may be used. The polymerizable group to introduce | transduces can be suitably selected according to the structure of the structural unit which resin (A) has.

  Specific examples of the monomer (C) include 2- [2′-hydroxy-5′-methacryloyloxy] ethylphenyl] -2H-benzotriazole (trade name RUVA-93, manufactured by Otsuka Chemical Co., Ltd.), 2- [ 2′-hydroxy-5′-methacryloyloxy] phenyl] -2H-benzotriazole, 2- [2′-hydroxy-3′-t-butyl-5′-methacryloyloxy] phenyl] -2H-benzotriazole, and the like. It is done.

  Specific examples of the monomer (C) other than the above include triazine derivatives represented by the following formulas (5), (6) and (7), or benzotriazole represented by the following formula (8). Derivatives.

  In addition, all the above-mentioned benzotriazole derivatives as specific examples of the monomer (C) are solid at 25 ° C.

  When the resin (A) contains UVA units, the content of the units in the resin (A) is preferably 20% by weight or less, and more preferably 15% by weight or less. When the content of the UVA unit in the resin (A) exceeds 20% by weight, the heat resistance as the resin composition is lowered, and the production cost of the resin composition becomes very high.

  The weight average molecular weight of the resin (A) is, for example, in the range of 1,000 to 300,000, preferably in the range of 5,000 to 250,000, more preferably in the range of 10,000 to 200,000, and still more preferably in the range of 50,000 to 200,000.

  Resin (A) can be manufactured by a well-known method. The resin (A) having a lactone ring structure in the main chain can be produced, for example, by the methods described in JP-A-2006-96960, JP-A-2006-171464, and JP-A-2007-63541. A resin (A) having an N-substituted maleimide structure in the main chain, a resin (A) having a glutaric anhydride structure in the main chain, and a resin (A) having a glutarimide structure in the main chain are disclosed in JP-A-2007-31537. Can be produced by the methods described in Japanese Patent Publication No. WO 2007/26659 pamphlet and WO 2005/108438 pamphlet. The resin (A) having a maleic anhydride structure in the main chain can be produced by the method described in JP-A-57-153008.

[UVA (B)]
UVA (B) is not particularly limited as long as it is a benzotriazole ultraviolet absorber that is liquid at 25 ° C. “Liquid at 25 ° C.” refers to a state in which fluidity is maintained when the temperature of UVA (B) is 25 ° C. The viscosity of UVA (B) at 25 ° C. is preferably 5000 mPa · s or more, and particularly preferably 15000 mPa · s or more. The viscosity of UVA (B) can be measured based on the JIS K7117-1 standard using a Brookfield viscometer.

In the UVA (B), the molar extinction coefficient of the maximum absorption wavelength with respect to light in the wavelength range of 300 nm to 380 nm is preferably 10,000 (L · mol ⁻¹ · cm ⁻¹ ) or more in a chloroform solution, and 15000 (L · mol ^{− 1} · cm ⁻¹ ) or more is more preferable.

  UVA (B) preferably has a structure represented by the following formula (1).

R ¹ in the above formula (1) is an alkyl group having 4 to 20 carbon atoms, R ² is an alkyl group or alkyl ester group having 8 to 20 carbon atoms, and R ³ is a hydrogen atom or a halogen atom. . The alkyl ester group is preferably a group represented by the formula “—R ¹³ —C (═O) OR ¹⁴ ”. In the above formula, R ¹³ and R ¹⁴ are alkyl groups. R ¹ , R ¹³ and R ¹⁴ may be linear alkyl groups or branched alkyl groups.

In the above formula (1), the sum of the molecular weight of R ¹ and R ² is preferably larger than the molecular weight of the portion excluding the R ¹ and R ^2.

  Specific examples of such UVA (B) are given in the following formulas (9) and (10).

Commercially available UV absorber containing as a main component UVA (B) represented by the above formula (9), for example, a TI N UVIN384-2 (manufactured by Ciba Specialty Chemicals Inc.). Further, the commercial UV absorbers as main components UVA (B) represented by the above formula (10), for example, a TI N UVIN109 (manufactured by Ciba Specialty Chemicals Inc.).

[Resin composition]
The content of UVA (B) in the resin composition of the present invention is not particularly limited. For example, the thermoplastic resin contained in the composition is 100 parts by weight of the thermoplastic resin including the resin (A). When the total weight of the resin is 100 parts by weight, the range is 0.5 to 5 parts by weight. When the content of UVA (B) is excessively small, sufficient ultraviolet absorbing ability cannot be obtained. On the other hand, when the content of UVA (B) becomes excessively large, the demerit that bleed-out occurs at the time of molding or after molding becomes larger than the merit of increasing the ultraviolet absorbing ability.

  The content of UVA (B) in the resin composition of the present invention is preferably 1 to 5 parts by weight, more preferably 1 to 4 parts by weight with respect to 100 parts by weight of the thermoplastic resin. Part by weight is more preferred.

  The main component of the thermoplastic resin contained in the resin composition of the present invention is the resin (A). Specifically, the proportion of the resin (A) in the entire thermoplastic resin contained in the resin composition of the present invention is 60% by weight or more, preferably 70% by weight or more, more preferably 85% by weight or more. . In other words, the resin composition of the present invention has a thermoplastic resin other than the resin (A) in a proportion of less than 40% by weight (preferably 30% by weight) based on the total thermoplastic resin contained in the composition. In the range of less than 15% by weight, and more preferably in the range of less than 15% by weight.

  Examples of such thermoplastic resins include olefin polymers such as polyethylene, polypropylene, ethylene-propylene copolymer, and poly (4-methyl-1-pentene); halogen-containing polymers such as vinyl chloride and chlorinated vinyl resins. Polymers: polystyrene, styrene polymers such as styrene-methyl methacrylate copolymer, styrene-acrylonitrile copolymer, acrylonitrile-butadiene-styrene block copolymer; polyesters such as polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate; nylon 6, polyamides such as nylon 66 and nylon 610; polyacetal: polycarbonate; polyphenylene oxide; polyphenylene sulfide: polyetheretherketone; polysulfone Polyether sulfone; polyoxyethylene Penji alkylene; polyamideimide; polybutadiene rubber ABS resin or blended with acrylic rubber, rubber-like polymer such as ASA resin; and the like. The rubbery polymer preferably has on its surface a graft portion having a composition compatible with the resin (A). When the rubbery polymer is in the form of particles, the average particle size is determined according to the present invention. From the viewpoint of improving transparency when the resin composition is a resin film, 300 nm or less is preferable, and 150 nm or less is more preferable.

  Among the thermoplastic resins exemplified above, a styrene-acrylonitrile copolymer and a vinyl chloride resin are preferable because of excellent compatibility with the resin (A).

  The resin composition of the present invention has a high glass transition temperature (Tg) of 110 ° C. or higher. Depending on the structure of the resin (A) (for example, when the resin (A) has a ring structure in the main chain, the type of the ring structure or the content of the ring structure in the resin (A)), the resin composition of the present invention The Tg of the product is 120 ° C. or higher, and further 130 ° C. or higher.

  The resin composition of the present invention has an ultraviolet absorbing ability based on UVA (B). For example, when the film has a thickness of 100 μm, the transmittance for light with a wavelength of 380 nm is less than 30%, and in some cases 25%. Hereinafter, it can be further set to 20% or less. What is necessary is just to measure this transmittance | permeability based on prescription | regulation of JISK7361: 1997.

  The resin composition of the present invention has a high visible light transmittance based on the compatibility between the resin (A) and the UVA (B). For example, when the film has a thickness of 100 μm, the resin composition has a wavelength of 500 nm. The transmittance can be 80% or more, and in some cases 90% or more. This transmittance can be measured in the same manner as the transmittance for light having a wavelength of 380 nm.

  In the resin composition of this invention, the hue of the said composition (and the resin molded product obtained by shape | molding the said composition) can be improved with the combination of resin (A) and UVA (B) mentioned above.

  The resin composition of the present invention may contain a polymer having negative intrinsic birefringence. In this case, the degree of freedom in controlling the birefringence in the resin composition (and the resin molded product obtained by molding the composition) is improved, and the resin molded product formed from the resin composition of the present invention (for example, resin Use of the film as an optical member is expanded.

  Examples of the polymer having negative intrinsic birefringence include a copolymer of a vinyl cyanide monomer and an aromatic vinyl monomer. A specific example of such a copolymer is a styrene-acrylonitrile copolymer, which is excellent in compatibility with the acrylic resin (A) in a wide range of copolymer compositions. preferable.

  The styrene-acrylonitrile copolymer production method includes various polymerization methods such as an emulsion polymerization method, a suspension polymerization method, a solution polymerization method, and a bulk polymerization method. The optical member is prepared from the resin composition of the present invention. When forming, since the transparency and optical characteristics of the obtained optical member can be improved, it is preferable to use a styrene-acrylonitrile copolymer obtained by a solution polymerization method or a bulk polymerization method.

  The resin composition of the present invention preferably contains an antioxidant. Although it does not specifically limit as antioxidant, For example, well-known antioxidants, such as a hindered phenol type, a phosphorus type, or a sulfur type, can be used by 1 type or in combination of 2 or more types. In particular, 2,4-di-t-amyl-6- [1- (3,5-di-t-amyl-2-hydroxyphenyl) ethyl] phenyl acrylate (e.g., Sumitizer GS manufactured by Sumitomo Chemical), and 2-t-butyl-6- (3-t-butyl-2-hydroxy-5-methylbenzyl) -4-methylphenyl acrylate (for example, Sumilizer GM manufactured by Sumitomo Chemical Co., Ltd.) is a resin composition at the time of high temperature molding. This is preferable because it has a high effect of suppressing deterioration of objects.

  The addition amount of the antioxidant in the resin composition of the present invention is, for example, 0 to 10% by weight, preferably 0 to 5% by weight, and more preferably 0.1 to 2% by weight.

  The resin composition of the present invention may contain other additives. Other additives include, for example, light stabilizers, weather stabilizers, heat stabilizers, etc .; reinforcing materials such as glass fibers and carbon fibers; near infrared absorbers; tris (dibromopropyl) phosphate, triallyl phosphate Flame retardants such as antimony oxide; antistatic agents typified by anionic, cationic and nonionic surfactants; colorants such as inorganic pigments, organic pigments and dyes; organic fillers, inorganic fillers; resin modifiers Plasticizers; lubricants; flame retardants, and the like. The amount of the other additives added in the resin composition of the present invention is, for example, 0 to 5% by weight, preferably 0 to 2% by weight, and more preferably 0 to 0.5% by weight.

  The resin composition of the present invention can be formed into an arbitrary shape such as a film or sheet by a known molding technique such as injection molding, blow molding, extrusion molding or cast molding. The molding temperature may be appropriately set according to the characteristics of the resin composition, and is not particularly limited, but is, for example, in the range of 150 to 350 ° C, and preferably in the range of 200 to 300 ° C.

  The resin molded product obtained by molding the resin composition of the present invention has high ultraviolet absorption ability, heat resistance and transparency, has few defects such as bleed out, and further has light transmittance during actual use. The decrease in turbidity and the increase in turbidity are reduced.

[Method for Producing Resin Composition]
The resin composition of the present invention can be produced by mixing a thermoplastic resin mainly composed of the resin (A) and UVA (B) by a known method. The produced resin composition may be pelletized with a pelletizer or the like, if necessary.

  The timing which mixes a thermoplastic resin and UVA (B) is not specifically limited unless the above-mentioned various characteristics as a resin composition are inhibited. UVA (B) may be added during polymerization of a thermoplastic resin (for example, resin (A)), or after polymerization of the thermoplastic resin, the obtained thermoplastic resin and UVA (B) are mixed (for example, Melt kneading). The specific method for melt-kneading the thermoplastic resin and UVA (B) is not particularly limited. For example, the thermoplastic resin, UVA (B) and other components to be added may be simultaneously heated and melted and kneaded. Alternatively, after the thermoplastic resin and other components to be added are heated and melted, UVA (B) may be further added thereto and kneaded. Further, after the thermoplastic resin is heated and melted, UVA (B) and other components to be added may be further added and kneaded.

[Resin molded product]
The resin molded product of the present invention comprises the resin composition of the present invention. The resin molded product of the present invention has various characteristics based on the characteristics of the above-described resin composition of the present invention. For example, the resin molded product of the present invention has high ultraviolet absorption ability, heat resistance and transparency. For example, the resin molded product of the present invention has few defects such as bleed out. Further, for example, in the resin molded product of the present invention, a decrease in light transmittance and an increase in turbidity during actual use are reduced.

  Due to these characteristics, the resin molded product of the present invention can be suitably used as an optical member. In addition, due to its high heat resistance, it can be placed close to a heat generating part such as a light source.

  The shape of the resin molded product of the present invention is not particularly limited, and may be, for example, a film or a sheet.

  The thickness of the resin molded product of the present invention (the resin film of the present invention) that is a film is, for example, 1 μm or more and less than 350 μm, and preferably 10 μm or more and less than 350 μm. If the thickness is less than 1 μm, the strength as a resin film may be insufficient, and breakage or the like is likely to occur during post-processing such as stretching.

  The thickness of the resin molded product of the present invention which is a sheet (the resin sheet of the present invention) is, for example, from 350 μm to 10 mm, and preferably from 350 μm to 5 mm. When the thickness exceeds 10 mm, it becomes difficult to make the sheet thickness uniform, and it becomes difficult to use the resin sheet particularly as an optical member.

  The resin sheet and the resin film can be formed, for example, by extruding the resin composition of the present invention.

  The resin sheet and resin film of this invention have high Tg, for example, the value is 110 degreeC or more. Depending on the composition of the resin composition constituting the resin sheet and the resin film, the Tg can be 120 ° C. or higher, and further 130 ° C. or higher.

  The resin sheet and the resin film of the present invention have high ultraviolet absorption ability. For example, in the case of a film having a thickness of 100 μm, the transmittance for light having a wavelength of 380 nm can be less than 30%, in some cases 25% or less, and further 20% or less.

  The resin sheet and resin film of the present invention have high visible light transmittance. For example, when the film has a thickness of 100 μm, the transmittance for light having a wavelength of 500 nm can be 80% or more, and in some cases 90% or more. The method for measuring the transmittance of the film (sheet) with respect to light with a wavelength of 380 nm and light with a wavelength of 500 nm may follow the method described above.

  The resin sheet and the resin film of the present invention preferably have a tensile strength measured based on ASTM-D-882-61T of 10 MPa or more and less than 100 MPa, and more preferably 30 MPa or more and less than 100 MPa. When the said tensile strength is less than 10 Mpa, the mechanical strength as a resin sheet (film) may become inadequate. On the other hand, when the tensile strength exceeds 100 MPa, the workability decreases.

  The resin sheet and the resin film of the present invention preferably have an elongation of 1% or more measured based on ASTM-D-882-61T. Although the upper limit of the said elongation rate is not specifically limited, Usually, it is 100% or less. When the said elongation rate is less than 1%, the toughness as a resin sheet (film) may become inadequate.

  In the resin sheet and resin film of the present invention, the tensile modulus measured based on ASTM-D-882-61T is preferably 0.5 GPa or more, more preferably 1 GPa or more, and 2 GPa or more. More preferably. Although the upper limit of the said tensile elasticity modulus is not specifically limited, Usually, it is 20 GPa or less. When the said tensile elasticity modulus is less than 0.5 GPa, the mechanical strength as a resin sheet (film) may become inadequate.

  Various functional coating layers may be formed on the surface of the resin sheet and the resin film of the present invention as necessary. Examples of the functional coating layer include 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, a hard coat layer, and an ultraviolet ray. Examples thereof include a shielding layer, a heat ray shielding layer, an electromagnetic wave shielding layer, and a gas barrier layer. Moreover, the member which has the functional coating layer mentioned above may be laminated | stacked on the resin sheet and resin film of this invention. Lamination | stacking of the said member to a resin sheet (film) can be performed through an adhesive or an adhesive agent, for example.

  Although the use of the resin sheet and the resin film of the present invention is not particularly limited, it can be suitably used as an optical member due to its high transparency and ultraviolet absorbing ability. As the optical member, for example, an optical protective film (sheet), specifically, a protective film for various optical disc (VD, CD, DVD, MD, LD, etc.) substrates, or a liquid crystal display (LCD), etc. The polarizer protective film used for the polarizing plate with which an image display apparatus is provided is mentioned. Also, for example, as an optical film such as 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 a touch panel, or a diffusion plate, a light guide The resin sheet and the resin film of the present invention may be used as an optical sheet such as a retardation plate or a prism sheet.

  A polarizer protective film will be described as an example. In the LCD, a pair of polarizing plates is arranged so as to sandwich the liquid crystal cell based on the image forming method. The polarizing plate generally includes a polarizer made of a resin film such as polyvinyl alcohol, and a polarizer protective film for protecting the polarizer. According to the polarizer protective film of the present invention, deterioration of the polarizer due to ultraviolet rays can be suppressed due to its high ultraviolet absorbing ability. Further, the high heat resistance makes it possible to dispose the polarizing plate close to the light source, and the high transparency makes it possible to form an image display device having excellent image display characteristics.

  Although the structure of a polarizing plate is not specifically limited, Usually, it has the structure where the polarizer was pinched | interposed by a pair of polarizer protective film.

  A polarizing plate provided with the polarizer protective film of the present invention (polarizing plate of the present invention) can be used for image display devices including LCDs.

[Production method of resin molded product]
As described above, the method for producing a resin molded product of the present invention is not particularly limited, but an example of a method for producing a resin film as a resin molded product will be shown below. This manufacturing method can also be applied to a method for manufacturing a resin sheet.

  As a method for producing a resin film from the resin composition of the present invention, there is an extrusion molding method. As a specific example, after each component constituting the resin composition is pre-blended with a mixer such as an omni mixer, the resulting mixture may be extrusion kneaded from a kneader. The kneader used for extrusion kneading is not particularly limited, and for example, a known kneader such as a single screw extruder, a twin screw extruder, or a pressure kneader can be used.

  Further, a separately formed resin composition may be melt-extruded. Examples of the melt extrusion method include a T-die method and an inflation method, and the molding temperature at that time is preferably 200 to 350 ° C., more preferably 250 to 300 ° C., further preferably 255 to 300 ° C., Especially preferably, it is 260 to 300 degreeC.

  When the T-die method is used, a resin film wound into a roll can be obtained by attaching a T-die to the tip of the extruder and winding the film extruded from the T-die. At this time, it is also possible to control the temperature and speed of winding and to stretch (uniaxial stretching) in the extrusion direction of the film. Further, the film may be stretched in a direction perpendicular to the extrusion direction, and sequential biaxial stretching or simultaneous biaxial stretching may be performed.

  When an extruder is used for extrusion molding, the type is not particularly limited and may be uniaxial, biaxial, or multiaxial, but its L / D value is (L is the value of the extruder) 10 to 100, preferably 20 to 50, more preferably 25 to 40, in order to sufficiently plasticize the resin composition and obtain a good kneaded state. preferable. When the L / D value is less than 10, the resin composition cannot be sufficiently plasticized and a good kneaded state may not be obtained. On the other hand, if the L / D value exceeds 100, the resin in the composition may be thermally decomposed due to excessive generation of shear heat to the resin composition.

  In this case, the set temperature of the cylinder is preferably 200 ° C. or higher and 300 ° C. or lower, and more preferably 250 ° C. or higher and 300 ° C. or lower. If setting temperature is less than 200 degreeC, the melt viscosity of a resin composition will become high too much, and the productivity of a resin film will fall. On the other hand, if the set temperature exceeds 300 ° C., the resin in the resin composition may be thermally decomposed.

  When an extruder is used for extrusion molding, the shape is not particularly limited, but the extruder preferably has one or more open vent portions. By using such an extruder, the decomposition gas can be sucked from the open vent portion, and the amount of volatile components remaining in the obtained resin 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 state, and the degree of pressure reduction is 931 to 1.3 hPa (700 to 1 mmHg) as the pressure of the open vent portion. The range is preferable, and the range of 798 to 13.3 hPa (600 to 10 mmHg) is more preferable. When the pressure in the open vent portion is higher than 931 hPa, volatile components or monomer components generated by the decomposition of the resin tend to remain in the resin composition. On the other hand, it is difficult to keep the pressure of an open vent part lower than 1.3 hPa industrially.

  When producing a resin film used as an optical member such as an optical film, a resin composition filtered through a polymer filter may be formed as necessary. Since the foreign matter present in the resin composition can be removed by the polymer filter, defects in the appearance of the obtained film can be reduced. In addition, at the time of filtration by a polymer filter, a resin composition will be in a high temperature molten state. For this reason, the resin composition deteriorates when passing through the polymer filter, gas components and colored deterioration products formed by the deterioration flow into the composition, and the resulting film is perforated, flow pattern, flow Defects such as streaks may be observed. This defect is particularly easily observed during continuous molding of a resin film. For this reason, when molding the resin composition filtered through the polymer filter, the molding temperature decreases the melt viscosity of the resin composition and shortens the residence time of the resin composition in the polymer filter, for example, 255. It is -300 degreeC and 260-320 degreeC is preferable.

  The configuration of the polymer filter is not particularly limited, but a polymer filter in which a large number of leaf disk filters are arranged in a housing can be suitably used. The filter material of the leaf disk type filter may be any of a type in which a metal fiber nonwoven fabric is sintered, a type in which metal powder is sintered, a type in which several metal meshes are laminated, or a hybrid type in which they are combined. The sintered type is most preferred.

  The filtration accuracy by the polymer filter is not particularly limited, but is usually 15 μm or less, preferably 10 μm or less, more preferably 5 μm or less. When the filtration accuracy is 1 μm or less, the residence time of the resin composition becomes longer, so that the thermal degradation of the composition increases and the productivity of the resin film decreases. On the other hand, when the filtration accuracy exceeds 15 μm, it is difficult to remove foreign substances in the resin composition.

The filtration area with respect to the resin processing amount per hour in the polymer filter is not particularly limited, and can be appropriately set according to the processing amount of the resin composition. The filtration area is, for example, 0.001 to 0.15 m ² / (kg / h).

  The shape of the polymer filter is not particularly limited. For example, an inner flow type having a plurality of resin flow ports and a resin flow path in the center pole; an 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. In particular, it is preferable to use an external flow type in which the resin stays are small.

  Although there is no restriction | limiting in particular in the residence time of the resin composition in a polymer filter, 20 minutes or less are preferable, 10 minutes or less are more preferable, and 5 minutes or less are further more preferable. Moreover, the filter inlet pressure and the filter outlet pressure at the time of filtration are, for example, 3 to 15 MPa and 0.3 to 10 MPa, respectively, and the pressure loss (pressure difference between the filter inlet pressure and the outlet pressure) is 1 MPa to 15 MPa. A range is preferred. 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 resin film tends to deteriorate. On the other hand, when the pressure loss exceeds 15 MPa, the polymer filter is easily damaged.

  What is necessary is just to set suitably the temperature of the resin composition introduce | transduced into a polymer filter according to the melt viscosity, for example, it is 250-300 degreeC, 255-300 degreeC is preferable and 260-300 degreeC is more preferable.

  The specific process of obtaining a resin film with few foreign substances and colored substances by filtration using a polymer filter is not particularly limited. For example, (1) a process in which a resin composition is formed and filtered in a clean environment, and then the resin composition is molded in a clean environment; (2) a resin composition having foreign matters or colored substances is cleaned A process in which the resin composition is subsequently molded in a clean environment after being filtered in an environment; (3) a process in which a resin composition having a foreign substance or a colored product is simultaneously filtered and molded in a clean environment; Etc. You may perform the filtration process of the resin composition by a polymer filter in multiple times for each process.

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

  The resin composition of the present invention is preferably extruded as it is after the production to obtain a resin film. Since heat history can be reduced as compared with the case where a resin film is formed by remelting the pellet obtained after pelletizing the resin composition, thermal deterioration of the resin composition can be suppressed. Moreover, in this method, since mixing of the foreign material from an environment can be suppressed, it can suppress that a foreign material exists in the obtained resin film, or coloring of the obtained resin film. A gear pump and a polymer filter are preferably arranged between the extruder and the T die.

  The resin film obtained by extrusion may be stretched as necessary. The type of stretching is not particularly limited, and may be uniaxial stretching or biaxial stretching. The mechanical strength of the resin film can be improved by stretching, and in some cases, birefringence can be imparted to the resin film. In addition, the resin composition of this invention can maintain optical isotropy after extending | stretching depending on the composition. The stretching temperature is not particularly limited, and a temperature in the vicinity of Tg of the resin composition is preferable. The draw ratio and the draw speed are not particularly limited.

  In order to stabilize the optical properties and mechanical properties of the resin film, heat treatment (annealing) may be performed as necessary after stretching.

  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.

  Initially, the evaluation method of the resin composition sample produced in the present Example is shown.

[Glass-transition temperature]
The glass transition temperature (Tg) of each sample was determined in accordance with JIS K7121 regulations. Specifically, a differential scanning calorimeter (manufactured by Rigaku Corporation, DSC-8230) is used to raise a temperature of about 10 mg from room temperature to 200 ° C. (temperature increase rate: 20 ° C./min) in a nitrogen gas atmosphere. From the obtained DSC curve, it evaluated by the starting point method. Α-alumina was used as a reference.

[Light transmittance]
The light transmittance of each sample was obtained by forming the film with a thickness of 100 μm by extrusion molding, and then using the spectrophotometer (manufactured by Shimadzu Corporation, UV-3100) to determine the transmittance of the film with respect to light having a wavelength of 380 nm and 500 nm. It evaluated by measuring. A specific method for forming a 100 μm thick film from each sample will be described later.

[Change in turbidity of film]
The amount of change in turbidity of the film formed from each sample was evaluated as follows. First, each sample was formed into a film having a thickness of 100 μm by extrusion, and 5 cm × 5 cm was cut out. Next, the turbidity of the cut out film was measured using a turbidimeter (Nippon Denshoku Industries Co., Ltd., NDH-1001DP), and the measured value was taken as the initial value. Next, the cut film is left in a hot air dryer (made by Tabai Co., Ltd.) maintained at 100 ° C. for 200 hours, and then the turbidity of the film after being left is measured again to determine the amount of change from the initial value. Asked. As described above, UVA bleed out can be considered as a factor for changing the turbidity of the film after molding.

Example 1
To a reaction vessel having an internal volume of 1000 L equipped with a stirrer, a temperature sensor, a cooling pipe, and a nitrogen introduction pipe, 40 parts by weight of methyl methacrylate (MMA), 10 parts by weight of methyl 2- (hydroxymethyl) acrylate ( MHMA), 50 parts by weight of toluene as a polymerization solvent, and 0.025 parts by weight of ADK STAB 2112 (manufactured by Asahi Denka Kogyo Co., Ltd.) as an antioxidant were charged, and the temperature was raised to 105 ° C. through nitrogen. At the start of reflux accompanying the temperature rise, 0.05 parts by weight of t-amyl peroxyisononanoate (manufactured by Arkema Yoshitomi, trade name: Luperox 570) was added as a polymerization initiator, and 0.10 parts by weight While t-amyl peroxyisononanoate was added dropwise over 3 hours, solution polymerization was allowed to proceed under reflux at about 105 to 110 ° C., followed by further aging for 4 hours.

Next, 0.05 parts by weight of 2-ethylhexyl phosphate (manufactured by Sakai Chemical Industry Co., Ltd., Phoslex A-8) is added to the resulting polymerization solution as a catalyst for the cyclization condensation reaction (cyclization catalyst). The cyclization condensation reaction for forming a lactone ring structure was allowed to proceed for 2 hours under reflux at 90 to 110 ° C. Subsequently, the autoclave by, after cyclocondensation reaction by polymerizing solution is heated at 240 ° C. 30 min, the resulting polymer solution, UVA (B) as a 2 weight parts of TI N UVIN384-2 (effective 95% by weight of components, manufactured by Ciba Specialty Chemicals) were added.

Next, the polymerization solution thus obtained has a barrel temperature of 240 ° C., a rotation speed of 100 rpm, a degree of vacuum of 13.3 to 400 hPa (10 to 300 mmHg), a rear vent number of 1, and a forevent number of 4. 45kg in terms of resin amount in a vent type screw twin screw extruder (Φ = 50.0mm, L / D = 30) with a leaf disk type polymer filter (filtration accuracy 5μ, filtration area 1.5m ² ) The resin composition (D-1) was obtained by carrying out devolatilization and filtration.

  The amount of UVA (B) added to the resin composition (D-1) is 100 parts by weight of the acrylic resin (A) (that is, 100 parts by weight of the thermoplastic resin contained in the composition (D-1)). 3.8 parts by weight).

(Example 2)
As resin (A), 90 parts by weight of glutarimide-containing acrylic resin (Rohm and Haas, KAMAX T-240) and 10 parts by weight of acrylonitrile-styrene copolymer (Asahi Kasei Chemicals, Stylac AS783) The mixture is charged into a hopper, and the mixture is subjected to a barrel temperature of 260 ° C., a rotation speed of 100 rpm, a degree of vacuum of 13 hPa, and a processing speed of 10 kg / hour in a twin-screw extruder having two vents (Φ30 mm, L / D = 42). It was made to melt on condition of this. Then, the formed melt, UVA (B) as 10 parts by weight of TI N UVIN384-2 (active ingredient 95%, manufactured by Ciba Specialty Chemicals) and, 10 parts by weight mixed solution of toluene, the vent The resin composition (D-2) was obtained by pressure injection from the front injection port at a rate of 0.8 kg / hour. When calculated from the processing speed of the resin (A) and the injection speed of the UVA (B), the amount of UVA (B) added to the resin composition (D-2) is the thermoplastic resin contained in the composition (D-2). (Glutarimide-containing acrylic resin and acrylonitrile-styrene copolymer) It is 3.8 parts by weight with respect to 100 parts by weight.

The glutarimide-containing acrylic resin used as the resin (A) has a glutarimide structure in which X ¹ is a nitrogen atom and R ^{7 to} R ⁹ are CH ₃ in the main chain in the above formula (3).

(Comparative Example 1)
To a reaction vessel having an internal volume of 1000 L equipped with a stirrer, a temperature sensor, a cooling pipe, and a nitrogen introduction pipe, 40 parts by weight of methyl methacrylate (MMA), 10 parts by weight of methyl 2- (hydroxymethyl) acrylate ( MHMA), 50 parts by weight of toluene as a polymerization solvent, and 0.025 parts by weight of ADK STAB 2112 (manufactured by Asahi Denka Kogyo Co., Ltd.) as an antioxidant were charged, and the temperature was raised to 105 ° C. through nitrogen. At the start of reflux accompanying the temperature rise, 0.05 parts by weight of t-amyl peroxyisononanoate (manufactured by Arkema Yoshitomi, trade name: Luperox 570) was added as a polymerization initiator, and 0.10 parts by weight While t-amyl peroxyisononanoate was added dropwise over 3 hours, solution polymerization was allowed to proceed under reflux at about 105 to 110 ° C., followed by further aging for 4 hours.

  Next, 0.05 parts by weight of 2-ethylhexyl phosphate (manufactured by Sakai Chemical Industry Co., Ltd., Phoslex A-8) is added to the resulting polymerization solution as a catalyst for the cyclization condensation reaction (cyclization catalyst). The cyclization condensation reaction for forming a lactone ring structure was allowed to proceed for 2 hours under reflux at 90 to 110 ° C. Subsequently, after the cyclization condensation reaction was advanced by heating the polymerization solution at 240 ° C. for 30 minutes by an autoclave, 0.75 parts by weight of SUMISORB300 (manufactured by Sumitomo Chemical Co., Ltd.) as UVA was added to the obtained polymerization solution. added. SUMISORB300 is a benzotriazole ultraviolet absorber that is solid at 25 ° C.

Next, the polymerization solution thus obtained has a barrel temperature of 240 ° C., a rotation speed of 100 rpm, a degree of vacuum of 13.3 to 400 hPa (10 to 300 mmHg), a rear vent number of 1, and a forevent number of 4. 45kg in terms of resin amount in a vent type screw twin screw extruder (Φ = 50.0mm, L / D = 30) with a leaf disk type polymer filter (filtration accuracy 5μ, filtration area 1.5m ² ) The resin composition (D-3) which is a comparative example was obtained by introducing at a processing rate of / hour, performing devolatilization and filtration.

  The addition amount of UVA in the resin composition (D-3) is 100 parts by weight of the acrylic resin (A) (that is, 100 parts by weight of the thermoplastic resin contained in the composition (D-3)). 1.5 parts by weight.

(Comparative Example 2)
A mixture of 100 parts by weight of glutaric anhydride-containing acrylic resin (Sumitomo Chemical Co., Sumipex B-TR) as resin (A) and 1.5 parts by weight of SUMISORB300 (Sumitomo Chemical Co., Ltd.) as UVA is charged into the hopper. In a twin-screw extruder having two vents (Φ30 mm, L / D = 42), the mixture was melted under the conditions of a barrel temperature of 260 ° C., a rotation speed of 100 rpm, a degree of vacuum of 13 hPa, and a processing speed of 10 kg / hour. And the resin composition (D-4) which is a comparative example was obtained. The amount of UVA added in the resin composition (D-4) is 100 parts by weight of the acrylic resin (A) (that is, 100 parts by weight of the thermoplastic resin contained in the composition (D-4)). 1.5 parts by weight.

The glutaric anhydride-containing acrylic resin used as the resin (A) has a glutaric anhydride structure in which X ¹ is an oxygen atom and R ⁷ and R ⁸ are each CH ₃ in the above formula (3). Have.

(Comparative Example 3)
In a 100-liter stainless steel polymerization tank equipped with a submerged tank and a stirrer, 42.5 parts by weight of methyl methacrylate, 5 parts by weight of N-phenylmaleimide, 0.5 parts by weight of styrene, 50 weights as a polymerization solvent Of toluene, 0.2 parts by weight of acetic anhydride as an organic acid, and 0.06 parts by weight of n-dodecyl mercaptan as a chain transfer agent were added, and nitrogen gas was bubbled for 10 minutes while stirring at a rotational speed of 100 rpm. I let you. Next, while maintaining the inside of the tank in a nitrogen atmosphere, the temperature in the polymerization tank was increased, and when the temperature in the tank reached 100 ° C., 0.075 parts by weight of t-butylperoxyisopropyl carbonate was added, At the same time, nitrogen bubbling was started in the submerged tank. Next, while adding a mixed solution of 2 parts by weight of styrene and 0.075 parts by weight of t-butylperoxyisopropyl carbonate to the tank at a rate over 5 hours, a polymerization temperature of 105 to 110 ° C. The polymerization reaction was allowed to proceed for 15 hours under reflux.

  Next, 9,10-dihydro-9-oxa-10-phosphanenanthrene-10-oxide (manufactured by Sanko Co., Ltd., HCA) as a phosphoric acid-based antioxidant and phenol-based polymer solution were obtained. As an antioxidant, 0.1 parts by weight of pentaerythrityl-tetrakis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate] (AO-60 manufactured by Asahi Denka Co., Ltd.) And 0.02 parts by weight were added.

  Next, the polymerization solution to which the antioxidant was added was converted into a vent type screw having a barrel temperature of 240 ° C., a rotation speed of 100 rpm, a degree of vacuum of 13.3 to 400 hPa (10 to 300 mmHg), a rear vent number of 1, and a forevent number of 4. Introduced into a shaft extruder (Φ = 29.75 mm, L / D = 30) at a processing rate of 2.0 kg / hour in terms of resin amount, and further 10 parts by weight of SUMISORB300 (manufactured by Sumitomo Chemical Co., Ltd.) A solution mixed with 10 parts by weight of toluene was pressure-injected at a rate of 0.06 kg / hr from an inlet before the third forvent to obtain a resin composition (D-5) as a comparative example. It was. When calculated from the processing rate of the resin (A) and the injection rate of UVA, the amount of UVA added to the resin composition (D-5) is 100 parts by weight of the acrylic resin (A) (that is, the composition (D -5)) with respect to 100 parts by weight of the thermoplastic resin contained).

  The results of evaluating the above properties for the resin composition samples of Examples 1-2 and Comparative Examples 1-3 are shown in Table 1 below. A resin film having a thickness of 100 μm was produced under the following extrusion molding conditions using a single-screw extruder having a cylinder diameter of 20 mm, a T-die having a width of 120 mm, and a roll for winding the film after molding: Extrusion temperature 270 ° C., T die temperature 270 ° C., winding speed 2.5 m / min, roll temperature 110 ° C.

  As shown in Table 1, in each resin composition of the examples, the turbidity of the resin film formed from the composition while realizing high glass transition temperature, ultraviolet absorption ability and visible light transmittance equivalent to those of the comparative example. The amount of change was greatly reduced. In the resin film formed from each resin composition of an Example, it is thought that the UVA bleed-out after film forming was suppressed compared with the comparative example.

  According to the present invention, a thermoplastic resin composition comprising a heat-resistant acrylic resin and UVA, which suppresses the occurrence of defects such as bleed out during molding and after molding even during molding at high temperatures. Can be provided.

  This resin composition has high ultraviolet absorption ability, heat resistance and transparency, has few defects such as bleed-out, and further suppresses a decrease in light transmittance and an increase in turbidity during actual use. The obtained resin molded product, for example, a resin film, can be suitably used particularly for use as an optical member.

Claims (12)

A thermoplastic resin mainly composed of an acrylic resin, and a benzotriazole ultraviolet absorber that is liquid at 25 ° C.,
The glass transition temperature (Tg) is 110 ° C. or higher,
The acrylic resin has a ring structure in the main chain;
A thermoplastic resin composition in which the ultraviolet absorber has a structure represented by the following formula (1).

R ¹ in the above formula (1) is an alkyl group having 4 to 20 carbon atoms, R ² is an alkyl group or alkyl ester group having 8 to 20 carbon atoms, and R ³ is a hydrogen atom or a halogen atom. Is an atom,
The sum of the molecular weight of R ¹ and R ² is greater than the molecular weight of the portion excluding the R ¹ and R ^2.   2. The acrylic resin according to claim 1, wherein the acrylic resin has at least one ring structure selected from a glutarimide structure, a glutaric anhydride structure, a maleic anhydride structure, an N-substituted maleimide structure, and a lactone ring structure in the main chain. Thermoplastic resin composition.   The thermoplastic resin composition according to claim 1, wherein the acrylic resin has a lactone ring structure in the main chain. The thermoplastic resin composition according to claim 3, wherein the lactone ring structure has a structure represented by the following formula (2).

In the above formula (2), R ⁴ , R ⁵ and R ⁶ are each independently a hydrogen atom or an organic residue having 1 to 20 carbon atoms. The thermoplastic resin composition according to claim 1, wherein R ¹ in the formula (1) is an alkyl group having 4 carbon atoms. The thermoplastic resin composition of Claim 1 whose said ultraviolet absorber is a ultraviolet absorber shown by the following formula | equation (9).

The content of the ultraviolet absorber in the composition is
The thermoplastic resin composition according to claim 1, which is 0.5 to 5 parts by weight with respect to 100 parts by weight of the thermoplastic resin. Claim 1-7 resin molded article comprising a thermoplastic resin composition according to any one of. The resin molded product according to claim 8 , which is a sheet or a film. Polarizer protective film made of a thermoplastic resin composition according to any one of claims 1-7. A polarizer, a polarizing plate and a polarizer protective film according to claim 1 0. An image display device comprising a polarizing plate according to claim 1 1.