JP2008163265A - Thermoplastic resin composition and extruded film or sheet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a UV absorbable thermoplastic resin composition having desired properties such as transparency, mechanical strength and moldability and particularly excellent in hue and capable of forming a molded article without foaming during the molding thereof and excellent in appearance, and an extruded film or sheet. <P>SOLUTION: This thermoplastic resin composition and an extruded film or sheet are a UV absorbable acrylic thermoplastic resin composition containing an acrylic resin as a main component and a UV absorber in an amount of 0.5 to 20% by weight based on the weight of the acrylic resin and satisfying the conditions: (A) having a glass transition temperature of 110°C or more; (B) when it is retained in an airtight container at 280°C for 20 minutes and discharged through an opening at one side of the container, foaming is not caused; and (C) having b-value of 3.0 or less as a film having 100 μm thereof; and an extruded film or sheet obtained from the acrylic thermoplastic resin composition. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a thermoplastic resin composition and an extruded film or sheet. More specifically, the present invention relates to a thermoplastic acrylic resin composition having an ultraviolet absorbing ability, which contains an acrylic resin and an ultraviolet absorber, and an extruded film or sheet comprising the resin composition.

  Acrylic resins represented by PMMA (polymethylmethacrylate) are excellent in optical properties such as high light transmittance, and are well balanced in mechanical strength, molding processability, and surface hardness. Widely used for transparent materials and optical related applications in various industrial parts. However, when exposed to light containing ultraviolet rays, there was a problem that transparency was lowered due to yellowing. For this reason, an ultraviolet absorber is generally added to an acrylic resin, but these ultraviolet absorbers have a low molecular weight and thus have problems such as foaming and bleeding out during molding. In addition, the amount of addition decreased due to transpiration during the molding process, and the ultraviolet absorption ability decreased, and the production process was contaminated.

  In order to solve these problems, benzotriazole-based UV absorbers, triazine-based UV absorbers, and benzophenone-based UV absorbers, which are highly effective when added in small amounts as UV absorbers, are widely used in combination with acrylic resins. (For example, see Patent Documents 1, 2, and 3).

  However, these ultraviolet absorbers have a problem in terms of hue, and are not satisfactory in terms of transpiration during molding.

  On the other hand, benzoxazinone-based UV absorbers are relatively excellent in hue and have a high melting point, so there is no problem of transpiration during molding, and they are widely used in combination with polyester resins. (For example, Patent Document 4). However, benzoxazine-based UV absorbers need to be added in a relatively large amount in order to obtain the necessary UV-absorbing ability in combination with acrylic resins, and are easily precipitated due to their high melting point. There has been a problem that the appearance of the molded product is impaired, and it has not been used.

  As an attempt to solve such a problem, a method of homo- or copolymerizing an ultraviolet-absorbing monomer is known. However, since general acrylic resins have insufficient heat resistance, the resin itself has poor shape stability at high temperatures, and there has been only a method of kneading, laminating or coating with other resins. Further, the ultraviolet absorbing monomer is generally bulky, and when it is copolymerized, the heat resistance of the resin is lowered. In particular, when the copolymerization amount of the ultraviolet absorbing monomer is increased in order to improve the ultraviolet absorbing ability, there is a problem that the heat resistance is remarkably reduced, and deterioration and coloring are likely to occur during molding.

  On the other hand, as a thermoplastic resin having both transparency and heat resistance, a lactone ring-containing polymer obtained by subjecting a polymer having a hydroxyl group and an ester group in a molecular chain to a lactone cyclocondensation reaction is known. (For example, refer to Patent Documents 5 to 6.) However, since these polymers have high heat resistance, it is known that the molding temperature is higher than that of general acrylic resins, and foam and silver streaks are likely to enter the molded product. In particular, when a bulky UV-absorbing monomer is copolymerized, the thermal stability during molding tends to deteriorate. Moreover, when a low molecular weight ultraviolet absorber was added, the transpiration of the additive at the time of molding and the contamination of the manufacturing process due to it were more likely to occur.

JP 2000-109766 A JP 2001-195914 A JP 2004-227843 A JP 2006-126315 A JP 2001-151814 A JP 2002-138106 A

The present invention has been made in view of the above situation, and has desired characteristics such as transparency, mechanical strength, molding processability, and is particularly excellent in thermal stability during molding, and less colored. An object is to provide a thermoplastic resin composition having ultraviolet absorbing ability.

  As a result of intensive studies, the inventors of the present invention have less coloring in a thermoplastic resin composition that satisfies a specific condition in which an ultraviolet absorber is blended with an acrylic resin having a high glass transition temperature. The present inventors have found that the above problems can be solved without the problems of moldability such as foaming, which is a concern with the formulation of No. 1, and have completed the present invention.

  In addition, the above problem can be solved by combining a benzoxazinone-based UV absorber, which has been conventionally unsuitable in combination with an acrylic resin, with a heat-resistant acrylic resin having a high glass transition temperature at a specific blending amount. I found it.

That is, this invention is a thermoplastic acrylic resin composition which has acrylic resin as a main component and contains 0.5-20 weight% of ultraviolet absorber with respect to this acrylic resin, Comprising:
(A) The glass transition temperature is 110 ° C. or higher;
(B) After being held at 280 ° C. for 20 minutes in an airtight container, no foaming occurs when discharged from one opening as a molten resin;
(C) The b value in a film having a thickness of 100 μm is 3.0 or less;
Is a thermoplastic acrylic resin composition having an ultraviolet absorbing ability.

  The ultraviolet absorber is preferably a benzoxazinone-based ultraviolet absorber.

  Furthermore, the present invention is an extruded film or sheet comprising the thermoplastic acrylic resin composition having the ultraviolet absorbing ability.

  According to the thermoplastic acrylic resin composition having ultraviolet absorbing ability of the present invention, since it contains a thermoplastic acrylic resin and an ultraviolet absorbent, it has high ultraviolet absorbing ability, transparency and mechanical strength. In addition to providing desired properties such as moldability, a molded product having excellent hue, no foaming during molding, and excellent appearance can be provided.

  Hereinafter, the present invention will be described in detail. In the present specification, the “main component” is intended to contain 50% by weight or more. In addition, “A to B” indicating a range indicates that the range is A or more and B or less.

  The thermoplastic resin composition according to the present invention contains an acrylic resin and an ultraviolet absorber.

≪Thermoplastic acrylic resin≫
The acrylic thermoplastic resin in the present invention is mainly a resin obtained by polymerizing acrylic acid, methacrylic acid and derivatives thereof, and is not particularly limited as long as the effects of the present invention are not impaired. Known acrylic thermoplastics Resin can be used. Preferable specific examples of the derivatives of acrylic acid and methacrylic acid include methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, n-butyl (meth) acrylate, and (meth) acrylic. T-butyl acid, n-hexyl (meth) acrylate, cyclohexyl (meth) acrylate, chloromethyl (meth) acrylate, 2-chloroethyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, (meth ) 3-hydroxypropyl acrylate, 2,3,4,5,6-pentahydroxyhexyl (meth) acrylate and 2,3,4,5-tetrahydroxypentyl (meth) acrylate, 2- (hydroxymethyl) Examples include methyl acrylate and methyl 2- (hydroxyethyl) acrylate, and one of these is included alone. May be present, or two or more of them may coexist. Of these, methyl (meth) acrylate is most preferred because of its excellent thermal stability.

  Moreover, it is preferable that the glass transition temperature of the acrylic thermoplastic resin in this invention is 110 degreeC or more. More preferably, it is 120 degreeC or more, More preferably, it is 130 degreeC or more. In terms of heat resistance, N-substituted maleimides such as phenylmaleimide, cyclohexylmaleimide, and methylmaleimide may be copolymerized, or in the molecular chain (also referred to as the main skeleton or main chain of the polymer). A lactone ring structure, a glutaric anhydride structure, a glutarimide structure, or the like may be introduced. Among them, a structure containing no nitrogen atom is preferable from the viewpoint of difficulty in coloring (yellowing) the film, and a film having a lactone ring structure in the main chain is preferable from the viewpoint of heat resistance and optical characteristics. Regarding the lactone ring structure in the main chain, a 4- to 8-membered ring may be used, but a 5- to 6-membered ring is more preferable, and a 6-membered ring is more preferable in view of the stability of the structure. Moreover, when the lactone ring structure in the main chain is a 6-membered ring, examples include the structure represented by the general formula (1) and Japanese Patent Application Laid-Open No. 2004-168882, and the lactone ring structure is introduced into the main chain. In synthesizing the previous polymer, it has a high polymerization yield, a polymer having a high content of lactone ring structure, and a copolymer with (meth) acrylate such as methyl methacrylate. In terms of good points, the structure represented by the general formula (1) is preferable.

(Wherein R ¹ , R ² and R ³ each independently represents a hydrogen atom or an organic residue having 1 to 20 carbon atoms. The organic residue may contain an oxygen atom.)
The thermoplastic acrylic resin in the present invention may have a polymer structural unit (repeating structural unit) constructed by polymerizing an ultraviolet absorbing monomer. Any UV-absorbing monomer may be used as long as it exhibits UV-absorbing properties, but a benzotriazole derivative, a triazine derivative, or a benzophenone derivative having a polymerizable group introduced therein is preferred.

  Specific examples of the ultraviolet absorbing monomer include 2- [2′-hydroxy-5′-methacryloyloxy] ethylphenyl] -2H-benzotriazole (trade name: RUVA-93, manufactured by Otsuka Chemical), 2- [2′-hydroxy-5′-methacryloyloxy] phenyl] -2H-benzotriazole, 2- [2′-hydroxy-3′-t-butyl-5′-methacryloyloxy] phenyl] -2H-benzotriazole, Examples include benzotriazole-based UV-absorbing monomers such as UVA-5 represented by the chemical formula; triazine derivatives such as UVA-2, UVA-3, and UVA-4 represented by the following chemical formula. These ultraviolet absorbing monomers may be used alone or in combination of two or more. Among these, a benzotriazole-based UV absorbing monomer and a triazine derivative are preferable, and a benzotriazole-based UV absorbing monomer is more preferable. 2- [2'-hydroxy-5'-methacryloyloxy] ethylphenyl] -2H-benzotriazole is particularly preferable from the viewpoint of ultraviolet absorption ability and coloring after molding. Since these monomers have a high UV-absorbing ability even in a small amount, they exhibit a sufficiently high effect in a thermoplastic methacrylic resin with a small amount of repeating units derived from the monomer. Accordingly, since the amount of structural units other than the UV-absorbing monomer unit in the thermoplastic methacrylic resin can be relatively increased, thermoplastic methacryl having sufficient thermoplasticity suitable for various uses such as films. System resin. Moreover, since there are few structural units derived from an ultraviolet-absorbing monomer, coloring of products such as thermoplastic methacrylic resins and films obtained from the resins can be sufficiently suppressed, and it can be suitably used for various applications. it can.

  UVA-2:

UVA-3:

UVA-4:

  UVA-5:

  The content of the ultraviolet-absorbing monomer unit contained in the thermoplastic methacrylic resin in the present invention is preferably 20% by weight or less. A form in which the content of the ultraviolet absorbing monomer is 15% by mass or less is also a preferred form of the present invention. More preferably, it is 1 to 15% by weight, still more preferably 2 to 10% by weight, and particularly preferably 3 to 10% by weight. If the content of the UV-absorbing monomer unit is less than 1% by weight, the resulting polymer will have insufficient UV-absorbing ability, and the compatibility with the added UV absorber will be reduced. Problems may occur during molding, which is not preferable. On the other hand, if the content of the UV-absorbing monomer unit exceeds 20% by weight, the resulting polymer has low heat resistance and is not economically preferable.

The thermoplastic methacrylic resin in the present invention is not particularly limited as long as it is a thermoplastic methacrylic resin having a polymer structural unit (repeating structural unit) constructed by polymerizing an ultraviolet absorbing monomer. . Among them, those having a glass transition temperature of 120 ° C. or higher are preferable, and examples thereof include lactone ring-containing polymers, maleimide polymers, glutaric anhydride polymers, glutarimide polymers, and the like. Among them, a lactone ring-containing polymer is preferable in terms of transparency, hue, and other optical properties.
The thermoplastic acrylic resin in the present invention has a weight average molecular weight of preferably 1,000 to 300,000, more preferably 5,000 to 250,000, still more preferably 10,000 to 200,000, particularly preferably, 50,000 to 200,000.

≪Ultraviolet absorber≫
The ultraviolet absorber in the present invention is preferably a benzoxazinone-based ultraviolet absorber. Since the benzoxazinone ultraviolet absorber has good compatibility with heat-resistant acrylic resins, particularly acrylic resins having a lactone ring structure, problems such as foaming and bleed-out during film molding hardly occur. Specifically, 2-p-methoxyphenyl (3,1-benzoxazin-4-one), 2-α-naphthyl (3,1-benzoxazin-4-one), 2-β-naphthyl (3,3) 1-benzoxazin-4-one), 2-p-phthalimidophenyl (3,1-benzoxazin-4-one), 2,2′-bis (3,1-benzoxazin-4-one), 2, 2 ′-(1,4-phenylene) bis [4H-3,1-benzoxazinone 4-one], 2,2 ′-(4,4′-diphenylene) bis (3,1-benzoxazine-4- ON), 2,2 ′-(2,6- or 1,5-naphthalene) bis (3,1-benzoxazin-4-one), 1,3,5-tri (3,1-benzoxazine-4) -On-2-yl), among which the melting point is particularly high and the absorption characteristics In particular, 2,2 ′-(1,4-phenylene) bis [4H-3,1-benzoxazinone 4-one] (manufactured by Nippon Cytec Industries, Inc., trade name: Siasorb UV-3638) is particularly used. preferable.

  As for melting | fusing point of the ultraviolet absorber in this invention, 250-350 degreeC is preferable. When the melting point is less than 250 ° C., foaming or bleeding out may occur during molding. On the other hand, if the melting point exceeds 350 ° C., the resin may not be uniformly mixed during molding and may aggregate and become cloudy.

  The compounding quantity of the ultraviolet absorber in this invention is 0.5 to 20 weight% with respect to acrylic resin. When the amount is preferably 1 to 15% by weight, more preferably 2 to 10% by weight, and the blending amount of the ultraviolet absorber is less than 0.5% by weight, the ultraviolet absorbing ability may be insufficient. On the contrary, if the blending amount of the ultraviolet absorber exceeds 20% by weight, foaming or smoke generation may occur during molding.

  The timing of adding the ultraviolet absorber is not particularly limited as long as the physical properties of the resin composition are not impaired. For example, an ultraviolet absorber is added at a predetermined stage during the production of an acrylic resin, or after an acrylic resin is produced, the acrylic resin, the ultraviolet absorber, and other components are simultaneously heated and melted and kneaded. Method of heating; Acrylic resin and other components are heated and melted, and a UV absorber is added thereto and kneaded; Acrylic resin is heated and melted, and there is a UV absorber and other components And the like.

≪Thermoplastic resin composition≫
The glass transition temperature (Tg) of the thermoplastic resin composition according to the present invention is 110 ° C. or higher. Preferably it is 115 degreeC or more, More preferably, it is 120 degreeC or more. Here, the glass transition temperature is a temperature at which a polymer molecule starts micro-Brownian motion, and there are various measurement methods. In the present invention, a differential scanning calorimeter (DSC) conforms to JIS-K7121. This is defined as the temperature obtained by the starting point method.

  When molding an acrylic thermoplastic resin composition having a high glass transition temperature, particularly, a resin having a high glass transition temperature having a ring structure such as a lactone ring structure, a glutaric anhydride structure, or a glutarimide structure in the molecular chain is included. In this case, foaming during high temperature molding becomes a problem. Therefore, in the present invention, it is defined that there is no foaming when the molten resin is discharged from one opening after being held at 280 ° C. for 20 minutes in a sealed container. Specifically, resin pellets were dried at 80 ° C. for 5 hours with a circulating hot air dryer, and 6 g of the dried pellets were charged into a melt indexer defined in JIS-K7210 adjusted to 280 ° C. for 20 minutes. Hold at 280 ° C. Thereafter, the resin is extruded in a strand shape with a load of 4.85 kg, and the foaming state of 10 cm of the strand from the lower marked line of the piston is visually observed to evaluate the foamability. Foaming occurs when there are 20 or more bubbles having a diameter of 0.5 mm or more in 10 cm of the strand. The case where there are less than 20 bubbles is defined as not foaming.

  The thermoplastic resin composition according to the present invention is less colored after molding and has a b value of 3.0 or less in a film having a thickness of 100 μm. More preferably, it is 2.0 or less. By setting the b value in such a range, it can be suitably used for various applications, particularly for engineering applications of optical materials. The thermoplastic acrylic resin composition having ultraviolet absorbing ability is often colored yellow, but as an optical material, it is preferably more colorless, and if the resin composition is colored, the value as an optical material is obtained. It will be lowered significantly.

  The thermoplastic resin composition according to the present invention preferably has a 5% weight loss temperature in thermogravimetric analysis (TG) of 280 ° C or higher, more preferably 290 ° C or higher, and further preferably 300 ° C or higher. The 5% weight loss temperature in thermogravimetric analysis (TG) is an index of thermal stability, and if it is less than 280 ° C., sufficient thermal stability may not be exhibited.

  The total amount of residual volatile components contained in the thermoplastic resin composition according to the present invention is preferably 5000 ppm or less, more preferably 3000 ppm or less. If the total amount of residual volatile components is more than 5000 ppm, coloring, volatilization, or formation defects such as silver streaks may occur due to alteration during formation.

  The thermoplastic resin composition according to the present invention may contain a thermoplastic resin other than the thermoplastic acrylic resin. These thermoplastic resins are not particularly limited in kind, but thermoplastic acrylic resins that are thermodynamically compatible are preferred in terms of improving transparency and mechanical strength.

  The content ratio of the thermoplastic acrylic resin and the other thermoplastic resin in the thermoplastic resin composition according to the present invention is preferably 60 to 99: 1 to 40% by weight, more preferably 70 to 97: 3 to 30. % By weight, more preferably 80 to 95: 5 to 20% by weight. When the content ratio of the thermoplastic acrylic resin in the thermoplastic resin composition is less than 60% by weight, the effects of the present invention may not be sufficiently exhibited.

  Other thermoplastic resins according to the present invention include, for example, olefin polymers such as polyethylene, polypropylene, ethylene-propylene copolymer, poly (4-methyl-1-pentene); vinyl chloride, chlorinated vinyl resin, and the like. Halogen-containing polymer; acrylic polymer such as polymethyl methacrylate; styrene polymer such as polystyrene, styrene-methyl methacrylate copolymer, styrene-acrylonitrile copolymer, acrylonitrile-butadiene-styrene block copolymer; polyethylene terephthalate , Polyesters such as polybutylene terephthalate and polyethylene naphthalate; polyamides such as nylon 6, nylon 66 and nylon 610; polyacetal: polycarbonate; polyphenylene oxide; I de polyether ether ketone; polysulfone; polyether sulfone: polyoxyethylene Penji alkylene; polyamideimide; polybutadiene rubber, rubber-like polymer such as acrylic rubber ABS resin or ASA resin blended with; and the like. The rubbery polymer preferably has a graft portion having a composition compatible with the lactone ring polymer of the present invention on the surface, and the average particle size of the rubbery polymer is transparent when formed into an extruded film. From the viewpoint of improving the property, the thickness is preferably 300 nm or less, and more preferably 150 nm or less.

  Thermoplastic acrylic resins, especially thermoplastic resins that are easily thermodynamically compatible with lactone ring-containing polymers, include co-polymers containing vinyl cyanide monomer units and aromatic vinyl monomer units. A polymer containing 50% by weight or more of a polymer, specifically, an acrylonitrile-styrene copolymer, a polyvinyl chloride resin, or a methacrylic acid ester may be used. Among them, acrylonitrile-styrene copolymer has good compatibility with a wide range of copolymer composition, and phase difference is obtained by combining positive phase difference of lactone ring and negative phase difference of acrylonitrile-styrene copolymer. It is particularly preferable because it can be controlled. In addition, it is confirmed by measuring the glass transition point of the thermoplastic resin composition obtained by mixing the thermoplastic acrylic resin and other thermoplastic resins in a thermodynamic manner by mixing them. Can do. Specifically, the glass transition point measured by the differential scanning calorimeter is observed only one point for the mixture of the thermoplastic acrylic resin and the other thermoplastic resin, so that the thermodynamic compatibility is achieved. I can say that.

  When an acrylonitrile-styrene copolymer is used as the other thermoplastic resin, an emulsion polymerization method, a suspension polymerization method, a solution polymerization method, a bulk polymerization method, or the like can be used as the production method. From the viewpoint of the transparency and optical performance of the optical film, it is preferably obtained by a solution polymerization method or a bulk polymerization method.

  The thermoplastic resin composition according to the present invention preferably contains an antioxidant. Although it does not specifically limit as antioxidant, Well-known antioxidants, such as a hindered phenol type, phosphorus type, and a sulfur type, may be used independently, or may use 2 or more types together. Among them, in particular, 2,4-di-t-amyl-6- [1- (3,5-di-t-amyl-2-hydroxyphenyl) ethyl] phenyl acrylate (manufactured by Sumitomo Chemical Co., Ltd., product) Name: Sumilizer GS) and 2-t-butyl-6- (3-t-butyl-2-hydroxy-5-methylbenzyl) -4-methylphenyl acrylate (manufactured by Sumitomo Chemical Co., Ltd., trade name: Sumilizer GM) ) Is preferred.

  The addition amount of the antioxidant is preferably 0 to 10% by weight, more preferably 0 to 5% by weight, and still more preferably 0.1 to 2% by weight.

  The thermoplastic resin composition according to the present invention may contain other additives. Other additives include, for example, light stabilizers, weather stabilizers, heat stabilizers and the like: 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 such as anionic, cationic and nonionic surfactants; colorants such as inorganic pigments, organic pigments and dyes; organic fillers and inorganic fillers: resin modifiers; organic Fillers and inorganic fillers; plasticizers; lubricants; antistatic agents; flame retardants; The content of other additives in the thermoplastic acrylic resin molded body is preferably 0 to 5% by weight, more preferably 0 to 2% by weight, and still more preferably 0 to 0.5% by weight.

  In the thermoplastic resin composition according to the present invention, the light transmittance at 500 nm at a thickness of 100 μm is preferably 80% or more and the light transmittance at 380 nm is less than 30%. By setting the light transmittance within such a range, it can be suitably used for various applications, particularly optical applications such as optical materials. It is preferable that the optical material is more colorless, and if the thermoplastic resin composition is colored, the product value as the optical material is significantly reduced. Since 500 nm is a wavelength in the visible light region, the light transmittance of this wavelength is 80% or more, that is, the absorption is less than 20%, the absorption of visible light is small, and the thermoplastic resin composition is It means that it becomes almost colorless. When the light transmittance at 500 nm is less than 80%, visible light is absorbed, coloring of the thermoplastic resin composition becomes remarkable, transparency is lowered, and there is a possibility that it cannot be suitably used as an optical material. The thermoplastic resin composition of the present invention is also suitably used as an optical material having an ultraviolet cut function. Ultraviolet rays are high in energy and cause deterioration of various materials. In order to protect the material from ultraviolet rays, there is a demand for a material that cuts ultraviolet rays. In order to obtain an ultraviolet-cutting material, it is preferable that the transmittance of at least 380 nm is less than 30%. If the transmittance at 380 nm is 30% or more, it cannot be said that the ultraviolet ray-cutting function is sufficient, the material cannot be sufficiently protected from ultraviolet rays, and the material may be deteriorated such as yellowing. The thermoplastic resin composition has a light transmittance at 380 nm of less than 30%, thereby suppressing transmission of light at 380 nm, which is a wavelength in the ultraviolet region, to less than 30%, and suppressing transmission of ultraviolet light. it can. Thus, it is preferable that the light transmittance of the thermoplastic resin composition is in the above range, and it can be suitably used as a film or sheet having a transparent appearance and having an ultraviolet cut function.

  That is, the thermoplastic resin composition according to the present invention has a light transmittance at 500 nm at a thickness of 100 μm, preferably 80% or more, more preferably 85% or more, and still more preferably 95% or more. If the light transmittance at 500 nm is less than 80%, the transparency is lowered and there is a possibility that it cannot be used for the intended purpose. Further, the light transmittance at 380 nm at a thickness of 100 μm is preferably less than 30%, more preferably less than 20%, and still more preferably less than 10%. If the light transmittance at 380 nm is 30% or more, ultraviolet rays cannot be sufficiently cut, and there is a risk of yellowing.

[Use and molding of thermoplastic resin composition]
The thermoplastic resin composition of the present invention is not only excellent in transparency and heat resistance, but also has properties such as low colorability, mechanical strength and molding processability, and has ultraviolet absorbing ability, so it is an extruded film or sheet. It is also useful. That is, a preferred embodiment of the thermoplastic resin composition of the present invention is an extruded film or sheet made of the above thermoplastic resin composition.

  As an example of a preferred application, a method for producing an extruded film from the thermoplastic resin composition of the present invention will be described in detail below.

[Extruded film]
A method for producing an extruded film from the thermoplastic resin composition of the present invention is not particularly limited. For example, a thermoplastic resin composition and other thermoplastic resins and other additives are mixed into a conventionally known mixing method. The extruded film can be produced from the thermoplastic resin composition in advance. As a method for producing this thermoplastic resin composition, for example, a method of pre-blending with a mixer such as an omni mixer and then extruding and kneading the obtained mixture can be employed. In this case, the kneader used for extrusion kneading is not particularly limited. For example, a conventionally known kneader such as an extruder such as a single screw extruder or a twin screw extruder or a pressure kneader is used. Can do.

  Examples of the melt extrusion method include a T-die method and an inflation method. In this case, the molding temperature of the extruded film is preferably 150 to 350 ° C., more preferably 200 to 300 ° C.

  When extrusion film forming is performed by the T-die method, a T-die is attached to the tip of a known single-screw extruder or twin-screw extruder, and the film extruded into a film shape can be obtained as a take-up roll film. . At this time, it is possible to adjust the temperature of the winding roll as appropriate and apply stretching in the extruding direction so that a uniaxial stretching process can be performed. Moreover, it is also possible to add processes, such as sequential biaxial stretching and simultaneous biaxial stretching, by adding the process of extending | stretching a film in the direction perpendicular | vertical to an extrusion direction.

  The extruded film of the present invention may be an unstretched film or a stretched film. When stretching, a uniaxially stretched film or a biaxially stretched film may be used. In the case of a biaxially stretched film, it may be a film that has been simultaneously biaxially stretched or a film that has been successively biaxially stretched. In the case of biaxial stretching, the mechanical strength is improved and the film performance is improved. The film of the present invention can suppress an increase in retardation even when stretched by mixing other thermoplastic resin compositions, and can maintain optical isotropy.

  The stretching temperature is preferably near the glass transition temperature of the thermoplastic resin composition of the extruded film raw material, and specifically, it is performed at (glass transition temperature-30) ° C. to (glass transition temperature + 100) ° C. It is preferably (glass transition temperature−20) ° C. to (glass transition temperature + 80) ° C. When it is lower than (glass transition temperature-30) ° C., a sufficient draw ratio cannot be obtained, which is not preferable. When the temperature is higher than (glass transition temperature + 100) ° C., the resin flows and stable stretching cannot be performed, which is not preferable.

  The court stretch ratio defined by the area ratio is preferably in the range of 1.1 to 25 times, more preferably in the range of 1.3 to 10 times. When it is less than 1.1 times, it is not preferable because it does not lead to improvement of toughness accompanying stretching. If it is larger than 25 times, the effect of increasing the draw ratio is not recognized.

  The stretching speed (one direction) is preferably in the range of 10 to 20000% / min, more preferably in the range of 100 to 10000% / min. If it is slower than 10% / min, it takes time to obtain a sufficient draw ratio, and the production cost is increased, which is not preferable. If it is faster than 20000% / min, the stretched extruded film may be broken, which is not preferable.

  In order to stabilize the optical isotropy and mechanical properties of the extruded film, heat treatment (annealing) or the like can be performed after the stretching treatment.

  Hereinafter, the present invention will be described more specifically with reference to Examples and Comparative Examples, but the present invention is not limited to these. Hereinafter, for convenience, “part by weight” may be simply referred to as “part”, and “liter” may be simply referred to as “L”.

(Glass-transition temperature)
The glass transition temperature was measured using a differential scanning calorimeter (DSC-8230, manufactured by Rigaku Corporation) under a nitrogen gas atmosphere, with α-alumina as a reference, in accordance with JIS-K7121, about 10 mg of a sample from room temperature to 200 ° C. It calculated by the starting point method from the DSC curve obtained by heating up at a heating rate of 20 ° C./min.

(Foaming)
The resin pellets were dried at 80 ° C. for 5 hours with a circulating hot air dryer. 6 g of dried pellets were put into a melt indexer defined in JIS-K7210 adjusted to 280 ° C., and kept at 280 ° C. for 20 minutes. Thereafter, the resin was extruded in a strand shape with a load of 4.85 kg, and the foaming state for 10 cm of the strand from the lower marked line of the piston was visually observed to evaluate the foamability according to the following criteria.

Foaming; 20 or more bubbles with a diameter of 0.5 mm or more do not foam in 10 cm of the strand; Less than 20 bubbles with a diameter of 0.5 mm or more in 10 cm of the strand (transmittance)
A film having a thickness of 100 μm was prepared by melt extrusion molding, and transmittances at 380 nm and 500 nm were measured using a spectrophotometer (manufactured by Shimadzu Corporation, apparatus name: UV-3100).

(B value)
The b value of the transmitted color was measured according to JIS-K7105 using a color difference meter (manufactured by Nippon Denshoku Industries Co., Ltd., product name: SE2000) prepared by melt extrusion molding of a film having a thickness of 100 μm.

<Weight average molecular weight>
The weight average molecular weight of the polymer was determined by polystyrene conversion of GPC (GPC system manufactured by Tosoh Corporation).

(Synthesis Example 1)
In a 30 L reaction kettle equipped with a stirrer, temperature sensor, condenser, and nitrogen inlet, 40 parts methyl methacrylate (MMA), 10 parts methyl 2- (hydroxymethyl) methyl acrylate (MHMA), 50 parts toluene , 0.025 part of ADK STAB 2112 (manufactured by Asahi Denka Kogyo Co., Ltd.) was charged, and the temperature was raised to 105 ° C. while passing nitrogen through this. When refluxed, 0.05 part of t-amylperoxy was used as an initiator. While adding isononanoate (trade name: Lupazole 570, manufactured by Atofina Yoshitomi Corp.), 0.10 parts of t-amylperoxyisonononanoate was added dropwise over 3 hours while refluxing (about 105- Solution polymerization at 110 ° C.), followed by further aging for 4 hours.

  To the obtained polymer solution, 0.05 part of 2-ethylhexyl phosphate (manufactured by Sakai Chemical Industry Co., Ltd., trade name: Phoslex A-8) was added and refluxed (about 90 to 110 ° C.) for 2 hours. A cyclization condensation reaction was performed. Subsequently, a heat treatment was carried out at 240 ° C. for 30 minutes by an autoclave to complete the cyclization condensation reaction.

  Subsequently, the polymer solution obtained by the cyclization condensation reaction was prepared by adding 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 (upstream). From the side, referred to as the first, second, third and fourth vents) vent type screw twin screw extruder (φ = 29.75 mm, L / D = 30) It was introduced at a treatment rate and devolatilized. At that time, separately prepared antioxidant / deactivator mixed solution was injected at a charging rate of 0.03 kg / hour using a high-pressure pump after the first vent. Further, after the third vent, ion exchange water was injected at a charging rate of 0.01 kg / hour using a high pressure pump.

  The antioxidant / deactivator mixed solution is 50 parts of Sumilizer GS (manufactured by Sumitomo Chemical Co., Ltd.) and 35 parts of zinc octylate (3.6% Nikka octix zinc manufactured by Nippon Chemical Industry Co., Ltd.) in 200 parts of toluene. It is dissolved.

  By the devolatilization operation, a transparent thermoplastic methacrylic resin (A) pellet having a lactone ring structure was obtained. The weight average molecular weight in terms of standard polystyrene by GPC was 148,000.

(Synthesis Example 2)
1. In a 30 L reaction kettle equipped with a stirrer, temperature sensor, cooling pipe and nitrogen introduction pipe, 41.5 parts of methyl methacrylate (MMA), 6 parts of methyl 2- (hydroxymethyl) acrylate (MHMA), 5 parts 2- [2′-hydroxy-5′-methacryloyloxy] ethylphenyl] -2H-benzotriazole (Otsuka Chemical Co., Ltd., trade name: RUVA-93), 50 parts toluene, 0.025 parts Adeka Stub 2112 (manufactured by Asahi Denka Kogyo Co., Ltd.), 0.025 part of n-dodecyl mercaptan was charged, and the temperature was raised to 105 ° C. while refluxing nitrogen. At the same time as t-amyl peroxy isononanoate (manufactured by Atofina Yoshitomi Corp., trade name: Lupazole 570) was added, 0.10 parts of t-amyl peroxyisononate Dropwise over 3 hours Nanoeto perform solution polymerization under reflux (about devices 105 through 110 ° C.), the mixture was aged over an additional 4 hours.

  To the obtained polymer solution, 0.05 part of 2-ethylhexyl phosphate (manufactured by Sakai Chemical Industry Co., Ltd., trade name: Phoslex A-8) was added and refluxed (about 90 to 110 ° C.) for 2 hours. A cyclization condensation reaction was performed. Subsequently, a heat treatment was carried out at 240 ° C. for 30 minutes by an autoclave to complete the cyclization condensation reaction.

  Subsequently, the polymer solution obtained by the cyclization condensation reaction was prepared by adding 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 (upstream). From the side, referred to as the first, second, third and fourth vents) vent type screw twin screw extruder (φ = 29.75 mm, L / D = 30) It was introduced at a treatment rate and devolatilized. At that time, separately prepared antioxidant / deactivator mixed solution was injected at a charging rate of 0.03 kg / hour using a high-pressure pump after the first vent. Further, after the third vent, ion exchange water was injected at a charging rate of 0.01 kg / hour using a high pressure pump.

  The antioxidant / deactivator mixed solution is 50 parts of Sumilizer GS (manufactured by Sumitomo Chemical Co., Ltd.) and 35 parts of zinc octylate (3.6% Nikka octix zinc manufactured by Nippon Chemical Industry Co., Ltd.) in 200 parts of toluene. It is dissolved.

  By the devolatilization operation, a transparent methacrylic resin (B) pellet having a transparent and ultraviolet-absorbing monomer unit was obtained. The weight average molecular weight in terms of standard polystyrene by GPC was 145000.

[Example 1]
7 parts of benzoxazinone-based ultraviolet absorber Siasorb UV-3638 (manufactured by Nippon Cytec Industries Co., Ltd.) is dry blended with 100 parts of the pellet of resin (A) obtained in Synthesis Example 1, and a 20 mmφ screw is used. The mixture was melt kneaded at a barrel temperature of 250 ° C. using a twin screw extruder. The physical properties of the pellets of the obtained resin composition were evaluated. result

Are summarized in Table 1.
Furthermore, the obtained resin composition pellets were extruded under the following conditions using a single screw extruder having a cylinder diameter of 20 mm at an extrusion temperature of 270 ° C. to produce a film having a thickness of 100 μm.

  (T-die: temperature 270 ° C., width 120 mm, film formation: two rolls with gloss, roll temperature 110 ° C., take-off speed: 2.5 m / min).

The physical properties of the obtained film were evaluated and the results are summarized in Table 1.
[Example 2]
To 100 parts of the resin (B) pellets obtained in Synthesis Example 2, 3 parts of benzoxazinone UV absorber Siasorb UV-3638 (manufactured by Nippon Cytec Industries, Ltd.) was dry blended, and a 20 mmφ screw was used. The mixture was melt kneaded at a barrel temperature of 250 ° C. using a twin screw extruder.

The physical properties of the pellets of the obtained resin composition were evaluated. The results are summarized in Table 1.
Furthermore, the obtained resin composition pellets were extruded under the following conditions using a single screw extruder having a cylinder diameter of 20 mm at an extrusion temperature of 260 ° C. to produce a film having a thickness of 100 μm.

  (T-die: temperature 260 ° C., width 120 mm, film formation: two rolls with gloss, roll temperature 110 ° C., take-off speed: 2.5 m / min).

The physical properties of the obtained film were evaluated and the results are summarized in Table 1.
[Comparative Example 1]
For the resin (A) obtained in Synthesis Example 1, a benzotriazole-based ultraviolet absorber ADK STAB LA-31 (manufactured by Asahi Denka Kogyo Co., Ltd.) was dry blended, and using a twin screw extruder having a 20 mmφ screw, Melt kneading was performed at a barrel temperature of 250 ° C.

The physical properties of the pellets of the obtained resin composition were evaluated. The results are summarized in Table 1.
Furthermore, the obtained resin composition pellets were extruded under the following conditions using a single screw extruder having a cylinder diameter of 20 mm at an extrusion temperature of 270 ° C. to produce a film having a thickness of 100 μm.

  (T-die: temperature 270 ° C., width 120 mm, film formation: two rolls with gloss, roll temperature 110 ° C., take-off speed: 2.5 m / min).

  The physical properties of the obtained film were evaluated and the results are summarized in Table 1.

The thermoplastic resin composition of the present invention has ultraviolet absorbing ability, has desired properties such as heat resistance, transparency, mechanical strength, and moldability, and is particularly excellent in hue and has no foaming during molding. Because it can give molded products with excellent appearance, it can be widely used for transparent materials and optical related applications that require light resistance, and in fields related to optical materials, especially applications that require UV absorbing ability Makes a great contribution.

Claims (3)

A thermoplastic acrylic resin composition comprising an acrylic resin as a main component and containing 0.5 to 20% by weight of an ultraviolet absorber relative to the acrylic resin, under the following conditions:
(A) The glass transition temperature is 110 ° C. or higher;
(B) After being held at 280 ° C. for 20 minutes in an airtight container, no foaming occurs when discharged from one opening as a molten resin;
(C) The b value in a film having a thickness of 100 μm is 3.0 or less;
A thermoplastic acrylic resin composition having ultraviolet absorbing ability, characterized by satisfying   2. The thermoplastic acrylic resin composition according to claim 1, wherein the ultraviolet absorber is a benzoxazinone ultraviolet absorber. An extruded film or sheet comprising the thermoplastic acrylic resin composition having ultraviolet absorbing ability according to claim 1.