JP2010229308A - Methacrylic resin composition for film production and impact modifier for film - Google Patents

Abstract

To provide a methacrylic resin composition for producing a film having excellent stress whitening resistance while maintaining good impact resistance, tensile strength and surface hardness.
A methacrylic resin composition for film production comprising 1 to 99 parts by weight of the following copolymer particles A and 99 to 1 part by weight of methacrylic resin B. Copolymer particles A: alkyl acrylate 1-98.9 wt%, alkyl methacrylate 1-98.9 wt%, monofunctional monomer having one radical polymerizable double bond 0-49.9 wt% % And a copolymer particle formed by polymerizing 0.1 to 20% by weight of a polyfunctional monomer having two or more double bonds capable of radical polymerization, wherein the weight ratio of alkyl acrylate to alkyl methacrylate Copolymer particles containing sites that are polymerized while continuously changing [selection figure] None

Description

  The present invention relates to a methacrylic resin composition for film production containing copolymer particles as an impact resistance improver and a methacrylic resin. Moreover, it is related with the impact resistance improving agent for films which consists of copolymer particle | grains. Such films are used, for example, as interior materials for automobiles, exterior materials for household electrical appliances, construction materials (exterior), and the like.

  As a methacrylic resin composition for film production containing copolymer particles and a methacrylic resin as impact resistance improver, a plurality of polymers obtained by polymerizing by changing the weight ratio of alkyl acrylate and alkyl methacrylate stepwise A methacrylic resin composition containing layer-structured copolymer particles and a methacrylic resin is known (see, for example, Patent Documents 1 to 4).

JP 51-129449 A JP-A-53-58554 Japanese Patent Laid-Open No. 11-80487 JP 2002-361712 A

  However, although the film made of the above conventional methacrylic resin composition has sufficient performance in terms of impact resistance, tensile strength and surface hardness, it is not always satisfactory in terms of stress whitening resistance. Accordingly, an object of the present invention is to provide a methacrylic resin composition for producing a film having excellent stress whitening resistance while maintaining good impact resistance, tensile strength and surface hardness.

  As a result of intensive studies, the present inventor has found that a methacrylic resin containing copolymer particles containing a portion formed by polymerization while the weight ratio of alkyl acrylate and alkyl methacrylate is continuously changed, and a methacrylic resin. The inventors have found that the above object can be achieved by a composition, and have completed the present invention.

That is, the present invention has the following configuration.
[1] A methacrylic resin composition for film production containing 1 to 99 parts by weight of the following copolymer particles A and 99 to 1 part by weight of methacrylic resin B.
Copolymer particles A: alkyl acrylate 1-98.9 wt%, alkyl methacrylate 1-98.9 wt%, monofunctional monomer having one radical polymerizable double bond 0-49.9 wt% % And a copolymer particle formed by polymerizing 0.1 to 20% by weight of a polyfunctional monomer having two or more double bonds capable of radical polymerization, wherein the weight ratio of alkyl acrylate to alkyl methacrylate Copolymer particles containing a portion formed by polymerization while continuously changing

[2] The methacrylic resin for film production according to [1], wherein the methacrylic resin B is obtained by polymerizing 70 to 100 parts by weight of an alkyl methacrylate and 0 to 30 parts by weight of a monomer copolymerizable therewith. Composition.

[3] A film comprising the methacrylic resin composition according to [1] or [2].

[4] An impact resistance improver for a film comprising the following copolymer particles A.
Copolymer particles A: alkyl acrylate 1-98.9 wt%, alkyl methacrylate 1-98.9 wt%, monofunctional monomer having one radical polymerizable double bond 0-49.9 wt% % And a copolymer particle formed by polymerizing 0.1 to 20% by weight of a polyfunctional monomer having two or more double bonds capable of radical polymerization, wherein the weight ratio of alkyl acrylate to alkyl methacrylate Copolymer particles containing sites obtained by polymerizing while continuously changing

  According to the methacrylic resin composition of the present invention, a film produced from the resin composition can exhibit excellent stress whitening resistance while maintaining good impact resistance, tensile strength, and surface hardness. . Further, by applying the copolymer particle A to the film as an impact resistance improver, in addition to good impact resistance, tensile strength and surface hardness, it is possible to impart excellent stress whitening resistance to the film. . Since such a film has the above-described performance, it can be suitably used for, for example, automobile interior materials, home appliance exterior materials, building materials (exterior), and the like.

It is a schematic diagram showing an example of the aspect of the power feed method which supplies each monomer component to a polymerization reactor.

  The methacrylic resin composition of the present invention contains copolymer particles A and methacrylic resin B. The copolymer particle A here is an alkyl acrylate of 1 to 98.9% by weight, an alkyl methacrylate of 1 to 98.9% by weight, and a monofunctional monomer 0 to 1 having one radical-polymerizable double bond. Copolymer particles obtained by polymerizing 49.9% by weight and 0.1 to 20% by weight of a polyfunctional monomer having two or more double bonds capable of radical polymerization, comprising alkyl acrylate and alkyl methacrylate Copolymer particles containing a portion formed by polymerization while continuously changing the weight ratio. By applying the copolymer particles A containing the specific site to the film, it is possible to impart excellent stress whitening resistance to the film in addition to good impact resistance, tensile strength, and surface hardness.

  In copolymer particle A, the weight percent of alkyl acrylate is preferably 30 to 90 weight percent. Moreover, as a weight% of alkyl methacrylate, it is preferable that it is 10 to 70 weight%. The weight percent of the monofunctional monomer is preferably 2 to 20 weight percent. The weight% of the polyfunctional monomer is preferably 0.5 to 10% by weight, and more preferably 1 to 5% by weight. When the polyfunctional monomer is less than 0.1% by weight, sufficient stress whitening resistance may not be obtained in a film-like methacrylic resin composition containing copolymer particles. When the polyfunctional monomer is more than 20% by weight, sufficient tensile strength may not be obtained in a film-like methacrylic resin composition containing copolymer particles.

  The alkyl acrylate can usually have an alkyl group having 1 to 8 carbon atoms. Among these, those having an alkyl group having 4 to 8 carbon atoms such as butyl acrylate and 2-ethylhexyl acrylate are preferable.

  The alkyl methacrylate can usually have an alkyl group having about 1 to 8 carbon atoms, such as methyl methacrylate, ethyl methacrylate, butyl methacrylate, 2-ethylhexyl methacrylate, methacrylic acid. Examples include cyclohexyl.

  Examples of the monofunctional monomer having one radical-polymerizable double bond include aromatic vinyl compounds such as styrene; vinylcyan compounds such as acrylonitrile.

  A polyfunctional monomer having two or more double bonds capable of radical polymerization can exhibit a function as a so-called crosslinking agent or grafting agent. Specific examples thereof include ethylene glycol dimethacrylate, butanediol diene. Unsaturated carboxylic acid diesters of glycols such as methacrylate; alkenyl esters of unsaturated carboxylic acids such as allyl acrylate, allyl methacrylate, allyl cinnamate; diallyl phthalate, diallyl maleate, triallyl cyanurate, And polyalkenyl esters of polybasic acids such as allyl isocyanurate; unsaturated carboxylic acid esters of polyhydric alcohols such as trimethylolpropane triacrylate; divinylbenzene and the like. In addition, these polyfunctional monomers may be used alone or in combination of two or more thereof. Among these polyfunctional monomers, alkenyl esters of unsaturated carboxylic acids and polyalkenyl esters of polybasic acids are preferred.

  Copolymer particle A has a site formed by polymerization while the weight ratio of alkyl acrylate and alkyl methacrylate is continuously changed. This is a site formed by polymerization while their weight ratio continuously changes from the center of the particle toward the outside. As specific examples, from the center of the particle toward the outside, (1) a continuous polymerization composition having a high alkyl acrylate ratio and a low alkyl methacrylate ratio to a polymerization composition having a low alkyl acrylate ratio and a high alkyl methacrylate ratio (2) A polymer composition continuously changing from a polymer composition having a low alkyl acrylate ratio and a high alkyl methacrylate ratio to a polymer composition having a high alkyl acrylate ratio and a low alkyl methacrylate ratio. Copolymer sites and the like. In (1), an alkyl acrylate unit: an alkyl methacrylate unit = 100: 0 (weight ratio) is continuously changed from an alkyl acrylate unit: alkyl methacrylate unit = 0: 100 (weight ratio). However, the present invention is not limited to this. In (2), an alkyl acrylate unit: an alkyl methacrylate unit = 0: 100 (weight ratio) is continuously changed from an alkyl acrylate unit: an alkyl methacrylate unit = 100: 0 (weight ratio). However, the present invention is not limited to this. In addition, the site | part which changes continuously from a soft copolymer part to a hard copolymer part toward the outer side from the center of the copolymer particle A by selecting suitably the kind of each said monomer, etc. Or a portion that continuously changes from a hard copolymer portion to a soft copolymer portion.

  The polymerization ratio of the monofunctional monomer or the polyfunctional monomer can be selected as appropriate, but the polyfunctional monomer can be continuously changed in its weight ratio in the same manner as the alkyl acrylate. It is preferable to perform polymerization.

  As described above, the copolymer particles A are continuously changed from a soft copolymer part to a hard copolymer part, or from a hard copolymer part to a soft copolymer part. Although what changed continuously is mentioned, Especially, what has a copolymer part whose glass transition temperature (Tg) is 25 degrees C or less and a copolymer part whose glass transition temperature (Tg) exceeds 25 degreeC. preferable.

  The copolymer particle A may be composed of a portion obtained by polymerization while continuously changing the weight ratio of alkyl acrylate and alkyl methacrylate, and further on the inside or outside of the portion. It may have a hard polymer layer. As such a hard polymer layer, a conventionally known polymer layer can be adopted as a hard layer of so-called acrylic rubber particles, preferably 70 to 100 parts by weight of alkyl methacrylate and other copolymerizable with this. It can be a copolymer obtained by polymerizing 0 to 30 parts by weight of monomers. Examples of the alkyl methacrylate here are the same as those described above. Examples of the monomer include acrylic acid esters such as methyl acrylate, ethyl acrylate, butyl acrylate, and cyclohexyl acrylate; aromatic vinyl compounds such as styrene; vinylcyan compounds such as acrylonitrile, and the like. Is mentioned.

  Next, the manufacturing method of the copolymer particle A is demonstrated. The copolymer particles A can be produced as a latex containing the particles by an emulsion polymerization method, and further, the particles can be obtained as a powder through a subsequent purification operation. Here, copolymer particles composed of portions that are continuously changing from a polymer composition having a high alkyl acrylate ratio and a low alkyl methacrylate ratio to a polymer composition having a low alkyl acrylate ratio and a high alkyl methacrylate ratio However, the present invention is not limited to this.

  Alkyl acrylate, alkyl methacrylate, monofunctional monomer having one radical-polymerizable double bond, and radical polymerization in an aqueous medium containing an emulsifier, a polymerization initiator, etc. under an inert gas atmosphere such as nitrogen They are polymerized by supplying a polyfunctional monomer having two or more possible double bonds. Here, the alkyl acrylate and the alkyl methacrylate are supplied while their weight ratio is continuously changed. Examples of such a supply method include a method referred to as a so-called power feed method, in addition to a method of supplying alkyl acrylate and alkyl methacrylate from different supply paths while changing the supply rate. As shown in FIG. 1, the power feed method here refers to a container 2A containing an alkyl acrylate first, a container 2B containing an alkyl methacrylate, and a monomer from the container 2A to the polymerization reactor 1. A line 3A and a pump 4A for transferring the components, and a line 3B and a pump 4B for transferring the monomer components from the container 2B to the container 2A are prepared. Next, the alkyl acrylate contained in the container 2A is transferred to the polymerization reactor 1 by the pump 4A through the line 3A, and the alkyl methacrylate contained in the container 2B is transferred to the container 2A by the pump 4B through the line 3B. Here, the alkyl acrylate contained in the container 2A and the alkyl methacrylate transferred from the container 2B are mixed in the container 2A. In addition, it can be made to mix uniformly by stirring the container 2A in this case. Subsequently, the mixed solution of alkyl acrylate and alkyl methacrylate contained in the container 2A is transferred to the polymerization reactor 1 by the pump 4A through the line 3A, and the alkyl methacrylate in the container 2B is pumped through the line 3B. 4B is transferred to the container 2A. By repeating this operation, the alkyl methacrylate ratio in the mixed liquid in the container 2A gradually increases (the alkyl acrylate ratio gradually decreases), and the alkyl methacrylate ratio transferred to the polymerization reactor 1 accordingly. Gradually increases (the ratio of alkyl acrylate gradually decreases), so that it is possible to polymerize them while continuously changing the weight ratio of alkyl acrylate and alkyl methacrylate (see FIG. 1). .

  The method for supplying a monofunctional monomer having one radical-polymerizable double bond or a polyfunctional monomer having two or more radical-polymerizable double bonds can be appropriately selected. The functional monomer and the polyfunctional monomer may be supplied to the polymerization reactor, respectively, and supplied to the polymerization reactor together with the alkyl acrylate or alkyl methacrylate in the containers 2A and 2B described above. May be. Among them, the polyfunctional monomer is preferably mixed with alkyl acrylate and supplied together into the polymerization reactor.

  In the case where the hard polymer layer is formed outside the site formed by polymerization while the weight ratio of the alkyl acrylate and the alkyl methacrylate is continuously changed, the hard polymer layer is continued following the polymerization reaction described above. What is necessary is just to add and polymerize the monomer used as the raw material which comprises.

  Examples of the aqueous medium include water and a mixed solvent of water and a water-miscible solvent. The aqueous medium is preferably added in a lump, divided or continuously so as to have a ratio of about 50 to 300 parts by weight with respect to 100 parts by weight of the total amount of each monomer as a raw material for the copolymer particles A. .

  The emulsifier is not particularly limited, and examples thereof include an anionic emulsifier. Examples of the anionic emulsifier include linear or branched sodium alkylbenzene sulfonate such as sodium dodecylbenzene sulfonate. The emulsifier is added all at once, in a divided manner or continuously so as to be a ratio of about 0.01 to 5 parts by weight with respect to 100 parts by weight of the total amount of each monomer as a raw material for the copolymer particles A. preferable.

  Examples of the polymerization initiator include persulfuric acid compounds such as potassium persulfate and ammonium persulfate. The polymerization initiator is added all at once, in a divided manner or continuously so as to be a ratio of about 0.01 to 1 part by weight with respect to 100 parts by weight of the total amount of monomers as raw materials for the copolymer particles A. Is preferred. Moreover, you may use pH adjusters, such as sodium carbonate, as needed. The polymerization temperature is usually about 60 to 90 ° C.

  In addition, in order to control the molecular weight of the copolymer particle A, a well-known chain transfer agent can be used. Examples of such chain transfer agents include primary, secondary and tertiary mercaptans having an alkyl group or substituted alkyl group such as methyl mercaptan, ethyl mercaptan, n-butyl mercaptan, sec-dodecyl mercaptan, t-butyl mercaptan, and phenyl. Aromatic mercaptans such as mercaptans, thioglycolic acid and its esters, ethylene glycol and the like can be mentioned.

  Moreover, the particle diameter of the copolymer particle A can be adjusted by adjusting the addition amount of an emulsifier, the usage-amount of each said monomer, etc. The particle size is 30 to 200 nm, preferably 50 to 150 nm, more preferably 60 to 120 nm. If it is 30 nm or less, sufficient tensile strength may not be obtained in a film-like methacrylic resin composition containing the particles. On the other hand, at 200 nm or more, sufficient stress whitening resistance and transparency may not be obtained in a film-like methacrylic resin composition containing the particles.

  Thus, a latex containing the copolymer particles A can be obtained. As a method for recovering the copolymer particles A from this latex, a conventionally known method can be adopted, for example, a method of coagulating by salting out, aciding out, freezing, etc., followed by filtration and then washing. And a method of recovering by spray drying. By applying the copolymer particle A to the film as an impact resistance improver, it is possible to impart excellent stress whitening resistance to the film in addition to sufficient impact resistance, tensile strength, and surface hardness.

  Copolymer particle A can be mixed with methacrylic resin B to make a methacrylic resin composition. Such a methacrylic resin composition is useful as a raw material for producing a film. In the methacrylic resin composition containing the copolymer particle A and the methacrylic resin B, the content of the copolymer particle A is preferably 1 to 99 parts by weight, and the content of the methacrylic resin B is 99 to 1. Part by weight is preferred. In addition, although this invention is a methacrylic resin composition containing the copolymer particle A and the methacrylic resin B, it is also possible to shape | mold the copolymer particle A in a film form independently.

  The methacrylic resin B is preferably a copolymer obtained by polymerizing 70 to 100 parts by weight of alkyl methacrylate and 0 to 30 parts by weight of another monomer copolymerizable therewith. As used herein, the alkyl methacrylate can usually have an alkyl group having about 1 to 8 carbon atoms, such as methyl methacrylate, ethyl methacrylate, butyl methacrylate, 2-ethylhexyl methacrylate. And cyclohexyl methacrylate. Examples of the monomer used herein include acrylic acid esters such as methyl acrylate, ethyl acrylate, butyl acrylate, and cyclohexyl acrylate; aromatic vinyl compounds such as styrene; vinylcyan such as acrylonitrile. Compounds and the like. When transparency is required in the methacrylic resin composition containing the copolymer particles A and the methacrylic resin B, the copolymer particles A and the methacrylic resin B are made to have substantially the same refractive index. It is preferable to select the type of each monomer constituting the polymer particle A and use them. As a method for producing the methacrylic resin B, for example, conventionally known methods such as bulk polymerization, suspension polymerization, emulsion polymerization, and solution polymerization can be employed.

  As a method of mixing the copolymer particles A with the methacrylic resin B, a conventionally known method such as a method of melt kneading with a single screw extruder or a twin screw extruder can be employed.

  The methacrylic resin composition may contain additives such as an anti-sticking agent, an ultraviolet absorber, a lubricant, an antioxidant, a plasticizer, an antistatic agent, and a dye as necessary. Among these, an ultraviolet absorber is preferably used for improving weather resistance. Examples of the UV absorber include commonly used benzotriazole UV absorbers, 2-hydroxybenzophenone UV absorbers, and salicylic acid phenyl ester UV absorbers. Specifically, as a benzotriazole ultraviolet absorber, 2,2′-methylenebis [4- (1,1,3,3-tetramethylbutyl) -6- (2H-benzotriazol-2-yl) phenol], 2- (5-methyl-2-hydroxyphenyl) -2H-benzotriazole, 2- [2-hydroxy-3,5-bis (α, α-dimethylbenzyl) phenyl] -2H-benzotriazole, 2- (3 , 5-Di-tert-butyl-2-hydroxyphenyl) -2H-benzotriazole, 2- (3-tert-butyl-5-methyl-2-hydroxyphenyl) -5-chloro-2H-benzotriazole, 2- (3,5-di-tert-butyl-2-hydroxyphenyl) -5-chloro-2H-benzotriazole, 2- (3,5-di-tert-amino Examples include 2- (2-hydroxyphenyl) -2H-benzotriazole and 2- (2'-hydroxy-5'-tert-octylphenyl) -2H-benzotriazole. Specific examples of the 2-hydroxybenzophenone ultraviolet absorber include 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-octyloxybenzophenone, 2,4-dihydroxybenzophenone, 2-hydroxy-4-methoxy-4 ′. -Chlorobenzophenone, 2,2'-dihydroxy-4-methoxybenzophenone, 2,2'-dihydroxy-4,4'-dimethoxybenzophenone and the like are exemplified. Specific examples of salicylic acid phenyl ester ultraviolet absorbers include p-tert-butylphenyl salicylic acid ester and p-octylphenyl salicylic acid ester.

  These ultraviolet absorbers can be used alone or in admixture of two or more. When the ultraviolet absorber is blended, the amount is usually 0.1% by weight or more, preferably 0.3% by weight or more, and preferably 2% by weight or less based on the total amount of the methacrylic resin composition.

  These additives can be added when the copolymer particles A are polymerized, or can be added when processed with a kneader, an extruder, a molding machine or the like.

  The methacrylic resin composition can be further formed into a film and can be suitably used, for example, for automobile interior materials, home appliance exterior materials, building materials (exterior), and the like. The thickness of the film is usually 0.03 to 0.5 mm, preferably 0.05 to 0.15 mm. In addition, as a method for producing the film, for example, a melt casting method, a melt extrusion method such as a T-die method or an inflation method, a calendar method, or the like can be employed. Among these, the method of forming a film by bringing at least one surface of a film-like product obtained by melt-extruding the methacrylic resin composition from a T die, for example, into contact with a roll or a belt is preferable in that a film having good surface properties can be obtained. . In particular, from the viewpoint of improving the surface smoothness and surface gloss of the film, a method of forming a film by bringing both surfaces of a film-like product obtained by melt extrusion molding the methacrylic resin composition into contact with the roll surface or belt surface. Is preferred.

  Moreover, the film which consists of this methacryl resin composition may be colored. As a coloring method, a pigment or a dye is contained in the methacrylic resin composition itself, and the resin composition itself before being formed into a film is colored. A film made of the methacrylic resin composition is immersed in a liquid in which the dye is dispersed. Although the dyeing | staining method etc. to color are mentioned, it is not specifically limited. A film made of this methacrylic resin composition can also be formed with a design layer by printing a pattern or the like on at least one surface thereof or providing a colored layer. These design layers are preferably applied to the side in contact with the base material constituting the interior wall material in order to give a deep appearance.

  The film made of this methacrylic resin composition may have at least one layer made of another thermoplastic resin laminated on one side. When a design layer such as printing or coloring is provided on one surface of the film, another resin is laminated on the surface. For example, the methacrylic resin composition and the thermoplastic resin are separately molded in advance into a film shape and laminated continuously between heating rolls, for example, as a laminated integral molding method with another thermoplastic resin. , Method of thermocompression bonding with a press, method of laminating simultaneously with pressure air or vacuum forming, method of laminating with an adhesive layer (wet lamination), one pre-molded resin film melt-extruded from a T-die And a method of laminating with the above resin. When these methods are used, a film made of a methacrylic resin composition formed into a film shape may be subjected to, for example, corona treatment on the surface to be bonded to the other thermoplastic resin substrate. Alternatively, an adhesive layer may be provided. Further, another thermoplastic resin film on which printing has been performed can be laminated. A resin film having a high compatibility with the methacrylic resin composition such as a polyvinyl chloride resin may be directly laminated with a film made of the methacrylic resin composition. In addition, a resin that is incompatible with the methacrylic resin composition, such as a polyolefin resin, requires an adhesive with a film made of the methacrylic resin composition. In addition, the other thermoplastic resin laminated | stacked on one side is colored, and the film which consists of a methacrylic resin composition remains colorless and transparent, and the base material of an interior wall material is stuck on the colored resin side, and a synthetic | combination form is carried out. If it does, it can be set as the outstanding decorating member which exhibits the coloring state with a deep feeling.

  Examples of the thermoplastic resin suitable for lamination with the film comprising the methacrylic resin composition include, for example, polycarbonate resin, polyethylene terephthalate resin, polyethylene resin, polypropylene resin, polystyrene resin, polyvinyl chloride resin, and other (meth) acrylic resins. And ABS (acrylonitrile-butadiene-styrene copolymer) resin. Among these, ABS (acrylonitrile-butadiene-styrene copolymer) resin is particularly preferable.

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated in detail, this invention is not limited only to a following example. “Parts” used in the following examples and comparative examples are all “parts by weight”, and “%” is “% by weight”. In addition, evaluation of Examples and Comparative Examples was performed by the following methods.

(Measurement of average particle diameter of polymer)
The weight average particle diameter was measured by a dynamic light scattering method using “DLS-7000” manufactured by Otsuka Electronics Co., Ltd.

(Evaluation of stress whitening)
A film having a thickness of 80 μm was used as a sample, and the test was performed at 23 ° C.
The film is sandwiched between two stainless steel plates with 15mmφ holes in a sample holder of a push-up tester (LLOYD INSTRUMENTS LTD .: LF-Plus Universal Test Machine). A 10 mmΦ dart with a hemispherical tip was pushed down 5 mm downward from the film surface at a speed of 1200 mm / min.
The stress-whitened state of the film deformed into a hemisphere at this time was visually observed and judged at the following level. In addition, the test was repeated 5 times and the average value of the judgment level was calculated | required. In addition, the one where the level is a low value means that the stress whitening resistance is excellent.
Level 0: No whitening is observed.
Level 1: extremely thin and whitening is observed. (Almost no whitening.)
Level 2: light whitening is observed. (Slightly whitened.)
Level 3: whitening is observed.
Level 4: Remarkably whitening is observed.

(surface hardness)
Based on JIS K5600-5-4, the pencil hardness of the film surface which consists of a methacrylic resin composition was measured.

(Tensile strength)
A film with a width of 10 mm is cut out from a film having a thickness of 80 μm, set at a chuck interval of 90 mm using a universal material testing machine (“1122RF55 type” manufactured by INSTRON) at 23 ° C., and a pulling speed of 50 mm / min. Measured at the speed of

(Measurement of notched Izod impact strength)
A test piece was prepared from the methacrylic resin composition pellets by injection molding, and a notched Izod impact strength was measured in accordance with JIS K7110.

Example 1
(A) Emulsion polymerization First, a 5 L glass polymerization reactor 1 is charged with a container 2A containing the monomer raw material (a), a container 2B containing the monomer raw material (I), and a polymerization reaction from the container 2A. A line 3A and a pump 4A for transferring the monomer component to the container 1 and a line 3B and a pump 4B for transferring the monomer component from the container 2B to the container 2A were prepared. Next, the entire amount of the aqueous medium raw material (c) was put into the polymerization reactor 1, and the temperature was raised to 80 ° C. with stirring in a nitrogen atmosphere.
Thereafter, the monomer component is transferred from the container 2A to the polymerization reactor 1 by the pump 4A through the line 3A at a rate of 0.29 parts / minute, and the monomer component is transferred from the container 2B to the container 2A by 0.2 parts / It was transferred by a pump 4B through a line 3B at a rate of minutes, and each monomer component was supplied in a total of 120 minutes.
Subsequently, the mixture is aged at the same temperature for 60 minutes with stirring, and from the center of the particle toward the outside, the polymerization composition having a high alkyl acrylate ratio and a low alkyl methacrylate ratio to a low alkyl acrylate ratio and a high alkyl methacrylate ratio. Copolymer particles A continuously changing to the composition [glass transition temperature (Tg) at the center calculated from the composition of the monomer = −53 ° C., glass transition temperature (Tg) at the outer surface = 103 A latex containing [° C.] was obtained. When this latex was measured by DLS, the weight average particle diameter of the copolymer particles A was 86 nm. Moreover, the solid content concentration in the obtained latex was 35%.

<Monomer raw material (A)>
Butyl acrylate 10.5 parts Allyl methacrylate 0.35 parts

<Monomer raw material (I)>
Methyl methacrylate 20.29 parts Styrene 2.20 parts Methyl acrylate 1.75 parts

<Aqueous medium raw material (U)>
Ion-exchanged water 65.0 parts Sodium carbonate 0.04 parts Sodium dodecylbenzenesulfonate 0.16 parts Potassium persulfate 0.013 parts

(B) Recovery of copolymer particles A 1.5 times by weight of ion-exchanged water was added to the latex and stirred, heated to 80 ° C., and then strongly stirred, 2% of the solid content in the latex. % Of magnesium sulfate was added to coagulate the copolymer particles A. Subsequently, the copolymer particles A were isolated by filtration. This copolymer particle A was put into ion-exchanged water heated to 80 ° C., which was 20 times by weight, and washed by filtering after stirring. This washing operation was repeated 5 times in total, and then dried with a vacuum dryer set at 80 ° C. to obtain powdery copolymer particles A.

(C) Methacrylic resin B used
As the methacrylic resin B, a pellet-shaped methacrylic resin obtained by bulk polymerization of 95% methyl methacrylate and 5% methyl acrylate was used.

(D) Production of film made of methacrylic resin composition and evaluation of the film 35 parts of copolymer particles A obtained in Example 1 (b) and 65 parts of methacrylic resin B were mixed with a supermixer, and biaxial extrusion It was melt-kneaded with a machine to make pellets. Next, this pellet was extruded through a T-die having a set temperature of 260 ° C. using a 20 mmφ single-screw extruder manufactured by Toyo Seiki Co., Ltd., and cooled so that both sides were completely in contact with two polishing rolls. A film made of a methacrylic resin composition having a thickness of 80 μm was obtained. The methacrylic resin composition was evaluated for notched Izod impact strength, and the film was evaluated for stress whitening property, pencil hardness, and tensile strength. The results are shown in Table 1.

Example 2
Except for changing the copolymer particles A obtained in Example 1 (b) to 50 parts and the methacrylic resin B to 50 parts, the same operation as in Example 1 was performed to obtain a film made of the methacrylic resin composition. It was. The methacrylic resin composition was evaluated for notched Izod impact strength, and the film was evaluated for stress whitening property, pencil hardness, and tensile strength. The results are shown in Table 1.

Example 3
Except for changing the copolymer particles A obtained in Example 1 (b) to 65 parts and the methacrylic resin B to 35 parts, the same operation as in Example 1 was performed to obtain a film made of the methacrylic resin composition. It was. The methacrylic resin composition was evaluated for notched Izod impact strength, and the film was evaluated for stress whitening property, pencil hardness, and tensile strength. The results are shown in Table 1.

Comparative Example 1
(A) Emulsion polymerization First, the entire amount of the aqueous medium raw material (a) shown below was charged into a 5 L glass reaction vessel, and the temperature was raised to 80 ° C. with stirring in a nitrogen atmosphere. The raw material (a) was continuously added over 30 minutes, and then aged for 45 minutes at the same temperature with continuous stirring to obtain innermost elastic polymer particles. Thereafter, the additional initiator raw material (c) was added and stirred, and the intermediate layer polymer raw material (d) was continuously added at the same temperature for 30 minutes, and further aged at the same temperature for 45 minutes with stirring, A two-stage polymer latex having an intermediate layer polymer formed outside the innermost layer elastic polymer was obtained. To this two-stage polymer latex, the following additional initiator raw material (e) is added and stirred, and then the hard polymer raw material (f) shown below is continuously added at 80 ° C. over 60 minutes, Subsequently, the mixture was aged at the same temperature for 45 minutes with stirring to obtain a three-stage polymer latex.

<Aqueous medium raw material (A)>
Ion-exchanged water 65.0 parts Sodium carbonate 0.04 parts Sodium dodecylbenzene sulfonate 0.10 parts Potassium persulfate 0.009 parts

<Innermost layer elastic polymer raw material (I)>
Butyl acrylate 7.1 parts Styrene 1.50 parts Allyl methacrylate 0.18 parts

<Additional initiator raw material (U)>
Sodium dodecylbenzenesulfonate 0.08 parts Potassium persulfate 0.009 parts

<Interlayer polymer raw material (D)>
Butyl acrylate 3.4 parts Methyl methacrylate 4.54 parts Styrene 0.62 parts Allyl methacrylate 0.175 parts

<Additional initiator raw material (e)>
Sodium dodecylbenzenesulfonate 0.16 parts Potassium persulfate 0.018 parts

<Rigid polymer raw material (f)>
Methyl methacrylate 15.75 parts Methyl acrylate 1.75 parts

  Thus, the innermost layer is an elastic polymer [Tg = −37 ° C.] of butyl acrylate / styrene / allyl methacrylate = 81/17/2 (weight ratio), and the intermediate layer is butyl acrylate / methyl methacrylate / Styrene / allyl methacrylate = 39/52/7/2 (weight ratio) elastic polymer [Tg = 20 ° C.], outermost layer is methyl methacrylate / methyl acrylate = 90/10 (weight ratio) hard polymer A latex containing a multistage polymer (three-stage polymer c1) having a spherical three-layer structure consisting of [Tg = 92 ° C.] and having a weight ratio of each layer of 25/25/50 was obtained. When the latex at each stage was measured by DLS, the weight average particle diameter was 55 nm, 70 nm, and 88 nm for the innermost layer elastic polymer, the intermediate layer polymer, and the third-stage polymer c1, respectively.

(B) Recovery of the three-stage polymer 2% by weight of the solid content in the latex was added to the latex after adding 1.5 times by weight of ion-exchanged water and stirring, heating to 80 ° C. and then stirring vigorously. An amount of magnesium sulfate corresponding to was added to coagulate the three-stage polymer c1. Subsequently, the three-stage polymer c1 was isolated by filtration. The three-stage polymer was put into ion-exchanged water heated to 80 ° C., which was 20 times by weight, washed and filtered after stirring. This washing operation was repeated 5 times in total and then dried with a vacuum dryer set at 80 ° C. to obtain a powdery three-stage polymer c1.

(C) Methacrylic resin B used
As the methacrylic resin B, a pellet-shaped methacrylic resin obtained by bulk polymerization of 95% methyl methacrylate and 5% methyl acrylate was used.

(D) Manufacture of a film comprising a methacrylic resin composition and evaluation of the film 50 parts of the three-stage polymer obtained in Comparative Example 1 (b) and 50 parts of the methacrylic resin B were mixed with a supermixer and biaxial extrusion It was melt-kneaded with a machine to make pellets. Next, this pellet was extruded through a T-die having a set temperature of 260 ° C. using a 20 mmφ single-screw extruder manufactured by Toyo Seiki Co., Ltd., and cooled so that both sides were completely in contact with two polishing rolls. A film made of a methacrylic resin composition having a thickness of 80 μm was obtained. The methacrylic resin composition was evaluated for notched Izod impact strength, and the film was evaluated for stress whitening property, pencil hardness, and tensile strength. The results are shown in Table 1.

Comparative Example 2
A methacrylic resin was prepared in the same manner as in Comparative Example 1 except that the composition and amount of the innermost layer elastic polymer raw material (A) and the composition and amount of the intermediate layer polymer raw material (D) were changed as follows. A film made of the composition was obtained. The methacrylic resin composition was evaluated for notched Izod impact strength, and the film was evaluated for stress whitening property, pencil hardness, and tensile strength. The results are shown in Table 1.

<Innermost layer elastic polymer raw material (I)>
Butyl acrylate 8.6 parts Allyl methacrylate 0.18 parts

<Interlayer polymer raw material (D)>
Butyl acrylate 1.75 parts Methyl methacrylate 6.6 parts Styrene 0.22 parts Allyl methacrylate 0.175 parts

  The three-stage polymer c2 in Comparative Example 2 has an innermost layer of butyl acrylate / allyl methacrylate = 98/2 (weight ratio) elastic polymer [Tg = −54 ° C.], and an intermediate layer of butyl acrylate / Methyl methacrylate / styrene / allyl methacrylate = 20 / 75.5 / 2.5 / 2 (weight ratio) hard polymer [Tg = 56 ° C.], outermost layer is methyl methacrylate / methyl acrylate = 90/10 It was a three-stage polymer having a spherical three-layer structure consisting of (weight ratio) of a hard polymer [Tg = 92 ° C.] and the weight ratio of each layer being 25/25/50. Further, when the latex at each stage was measured by DLS, the weight average particle diameters were 55 nm, 69 nm, and 87 nm for the innermost layer polymer, the intermediate layer elastic polymer, and the third-stage polymer c2, respectively.

1 Polymerization reactor 2A, 2B Container 3A, 3B Line 4A, 4B Pump

Claims (4)

A methacrylic resin composition for film production containing 1 to 99 parts by weight of the following copolymer particles A and 99 to 1 part by weight of methacrylic resin B.
Copolymer particles A: alkyl acrylate 1-98.9 wt%, alkyl methacrylate 1-98.9 wt%, monofunctional monomer having one radical polymerizable double bond 0-49.9 wt% % And a copolymer particle formed by polymerizing 0.1 to 20% by weight of a polyfunctional monomer having two or more double bonds capable of radical polymerization, wherein the weight ratio of alkyl acrylate to alkyl methacrylate Copolymer particles containing a portion formed by polymerization while continuously changing   The methacrylic resin composition for film production according to claim 1, wherein the methacrylic resin B is obtained by polymerizing 70 to 100 parts by weight of an alkyl methacrylate and 0 to 30 parts by weight of a monomer copolymerizable therewith.   A film comprising the methacrylic resin composition according to claim 1. An impact resistance improver for a film comprising the following copolymer particles A.
Copolymer particles A: alkyl acrylate 1-98.9 wt%, alkyl methacrylate 1-98.9 wt%, monofunctional monomer having one radical polymerizable double bond 0-49.9 wt% % And a copolymer particle formed by polymerizing 0.1 to 20% by weight of a polyfunctional monomer having two or more double bonds capable of radical polymerization, wherein the weight ratio of alkyl acrylate to alkyl methacrylate Copolymer particles containing a portion formed by polymerization while continuously changing

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