JP2012162675A - Methacrylic resin film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an acrylic resin film excellent in thermal shrinkability.SOLUTION: A methacrylic resin composition is made from acrylic ester crosslinked elastic body particles and a methacrylate ester polymer. Using the composition, the acrylic resin film excellent in thermal shrinkability, formability and workability can be obtained by specifying the amount of copolymerization of polyfunctional monomers in the acrylic ester crosslinked elastic body particles, the weight average molecular weight of methyl ethyl ketone soluble contents of the methacrylic resin composition, and the content of the crosslinked elastic body particles and by specifying the die slip aperture and the die temperature in extrusion molding.

Description

The present invention relates to a film formed by molding a methacrylic resin excellent in heat shrinkability.

A methacrylic resin film containing acrylic ester-based crosslinked elastic particles is excellent in transparency, weather resistance, hardness, and impact resistance. Therefore, it is laminated (laminated) on various materials such as plastic, wood, metal, etc. Widely used for preventing deterioration and maintaining aesthetics (for example, Patent Documents 1 and 2).

  In order to improve the transparency, weather resistance, hardness, impact resistance, etc. of the methacrylic resin film, for example, the layer structure and particle diameter of the crosslinked elastic particles are controlled, and the ultraviolet absorber has a specific chemical structure. A film made of a methacrylic resin composition for copolymerizing a polymer is disclosed (Patent Document 3). However, for example, regarding heat shrinkability when laminated on a thermoplastic resin sheet by a thermal lamination method, chemical resistance to a plasticizer blended with a vinyl chloride sheet, and moldability when laminated on a vinyl chloride sheet, Improvement was desired.

  Further, although a methacrylic resin composition for improving the characteristics of a methacrylic resin film has been disclosed (Patent Document 4), it is particularly necessary to further improve the heat shrinkage rate from the recent trend of high added value. It is coming.

  The acrylic resin film has the effect of improving the weather resistance of the laminated sheet by overlaying the acrylic resin film on the surface of the resin having poor weather resistance such as PVC, ABS, polycarbonate, etc. There are problems such as curling of the sheet, a decrease in the length after lamination, a decrease in yield, and an increase in total film thickness, and there is a demand for smaller heat shrinkage.

  On the other hand, a specific methacrylic resin composition capable of improving the heat shrinkage rate of the film has been disclosed (Patent Document 5), but the heat shrinkage rate has not been improved in terms of extrusion conditions. Further, from the market, a film having a heat shrinkage rate of 21% or less at 150 ° C., which is close to the temperature condition at the time of laminating, has been desired, but it has not been achieved with an acrylic resin film containing a rubber component.

Japanese Patent Laid-Open No. 11-60876 JP-A-6-73199 International Publication WO2005 / 095478 JP 2003-25412 A JP 2009-24112 A

A methacrylic resin film having excellent heat shrinkability is provided.

As a result of intensive studies, the present inventors have found that in a methacrylic resin composition containing acrylic ester-based crosslinked elastic particles and methacrylic ester-based polymer, a polyfunctional monomer in the acrylic ester-based crosslinked elastic particles. By specifying the copolymerization amount, the weight-average molecular weight of the methyl ethyl ketone-soluble component of the methacrylic resin, the content of the crosslinked elastic particles, and the die slip opening degree and die temperature at the time of extrusion molding The present inventors have found that a film having excellent heat shrinkage and excellent moldability and workability can be obtained, and the present invention has been achieved.

That is, the present invention is as follows.
Two or more non-conjugated double bonds per molecule are added to a monomer mixture (total 100% by weight) (b-1) containing 50 to 100% by weight of acrylic acid alkyl ester and 0 to 50% by weight of methacrylic acid alkyl ester. In the presence of the acrylic ester-based crosslinked elastic particles (B) obtained by copolymerizing the polyfunctional monomer (b-2) having, a methacrylic acid alkyl ester 50 to 100% by weight and an acrylic acid alkyl ester 0 It consists of a resin composition containing a methacrylic resin (C) obtained by polymerizing a monomer mixture containing -50 wt% (total 100 wt%) and having the following characteristics (1) to (6): A methacrylic resin film having a film thickness of 40 to 75 μm and a heat shrinkage in the flow direction of the film after heating at 150 ° C. of 21% or less.
(1) The methacrylic resin (C) is a acrylate ester-based crosslinked elastic particle (B) and then a two-layer structure polymer that is a methacrylic ester polymer (A).
(2) In the acrylic ester-based crosslinked elastic particles (B), the polyfunctional monomer (b-2) is 0.1 to 5 with respect to 100% by weight of the monomer mixture (b-1). % Copolymerized,
(3) The weight average molecular weight (Mw) of the methyl ethyl ketone-soluble component of the methacrylic resin (C) is 50,000 to 120,000 (polystyrene conversion),
(4) The average particle diameter of the acrylic ester-based crosslinked elastic particles (B) is 0.04 μm to 0.3 μm,
(5) The content of the acrylic ester-based crosslinked elastic particles (B) is 18 to 40% by weight,
(6) The copolymerization amount bm and the weight average molecular weight Mw of the polyfunctional monomer (b-2) in the acrylate ester-based crosslinked elastic particles (B) satisfy the following formula (i).
3 ≦ (Mw / 10000) / bm ≦ 8 (i)

  In the melt extrusion T-die method, the methacrylic resin film formed under the conditions that the die opening degree of the T die is 0.2 to 0.5 mm and the die temperature is 210 to 270 ° C.

  Moreover, the methacrylic resin laminated sheet which laminated | stacked the said methacrylic resin film or the methacrylic resin film shape | molded by the shaping | molding method of the said description on the thermoplastic resin sheet.

The methacrylic resin film obtained by the present invention is excellent in heat shrinkability.

The methacrylic acid ester polymer (A) in the present invention is a monomer mixture containing 50 to 100% by weight of a methacrylic acid alkyl ester and 0 to 50% by weight of an acrylic acid alkyl ester (a total of 100% by weight of the monomer mixture). Is polymerized in at least one stage. The monomer composition of the methacrylic acid ester polymer (A) more preferably contains 60 to 100% by weight of methacrylic acid alkyl ester and 0 to 40% by weight of acrylic acid alkyl ester. When the alkyl ester of acrylic acid exceeds 50% by weight, the heat resistance and hardness of the film that can be formed from the resulting methacrylic resin composition tend to decrease.

  In the present invention, the methacrylic acid alkyl ester constituting the methacrylic acid ester polymer (A) is preferably one having 1 to 12 carbon atoms in the alkyl group from the viewpoint of polymerization reactivity and cost. But you can. Specific examples thereof include, for example, methyl methacrylate, ethyl methacrylate, propyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, t-butyl methacrylate, and the like. These monomers are used as one kind. Alternatively, two or more kinds may be used in combination.

  The acrylic acid alkyl ester constituting the methacrylic acid ester polymer (A) in the present invention preferably has 1 to 12 carbon atoms in the alkyl group from the viewpoint of polymerization reactivity and cost, and is linear or branched. But you can. Specific examples thereof include, for example, methyl acrylate, ethyl acrylate, propyl acrylate, n-butyl acrylate, isobutyl acrylate, t-butyl acrylate, 2-ethylhexyl acrylate, and n-octyl acrylate. These monomers may be used alone or in combination of two or more.

In the methacrylic acid ester polymer (A) of the present invention, if necessary, an ethylenically unsaturated monomer copolymerizable with a methacrylic acid alkyl ester and an acrylic acid alkyl ester may be copolymerized. Absent. Examples of these copolymerizable ethylenically unsaturated monomers include vinyl halides such as vinyl chloride and vinyl bromide, vinyl cyanides such as acrylonitrile and methacrylonitrile, vinyl formate, vinyl acetate, and vinyl propionate. Vinyl esters such as styrene, vinyl toluene, aromatic vinyl derivatives such as α-methylstyrene, vinylidene halides such as vinylidene chloride and vinylidene fluoride, acrylic acid such as acrylic acid, sodium acrylate, calcium acrylate, and salts thereof , Β-hydroxyethyl acrylate, dimethylaminoethyl acrylate, glycidyl acrylate, acrylamide, acrylic acid alkyl ester derivatives such as N-methylol acrylamide, and methacrylates such as methacrylic acid, sodium methacrylate, calcium methacrylate Examples include sulfonic acid and its salts, methacrylamide, β-hydroxyethyl methacrylate, dimethylaminoethyl methacrylate, methacrylic acid alkyl ester derivatives such as glycidyl methacrylate, and the like. These monomers may be used alone. Two or more kinds may be used in combination.

  The acrylic ester-based crosslinked elastic particles (B) used in the present invention include a monomer mixture (b-1) containing 50 to 100% by weight of an acrylic acid alkyl ester and 0 to 50% by weight of a methacrylic acid alkyl ester, and A mixture composed of a polyfunctional monomer (b-2) having two or more non-conjugated double bonds per molecule is copolymerized in at least one stage. The monomer mixture (b-1) is more preferably 60 to 100% by weight of an acrylic acid alkyl ester and 0 to 40% by weight of a methacrylic acid alkyl ester. When the methacrylic acid alkyl ester exceeds 50% by weight, the hardness and impact resistance of the film that can be formed from the resulting methacrylic resin composition tend to be lowered.

  In the acrylic ester-based crosslinked elastic particle (B) of the present invention, an ethylenically unsaturated monomer copolymerizable with an alkyl methacrylate and an alkyl alkyl ester may be copolymerized as necessary. Absent.

  Specific examples of the acrylic acid alkyl ester, the methacrylic acid alkyl ester, and the ethylenically unsaturated monomer copolymerizable therewith used in the acrylic acid ester-based crosslinked elastic particle (B) of the present invention are the methacrylic acid esters. Examples thereof include those used for the polymer (A).

  As the polyfunctional monomer (b-2) used in the present invention, allyl methacrylate, allyl acrylate, triallyl cyanurate, triallyl isocyanurate, diallyl phthalate, diallyl maleate , Divinyl adipate, divinylbenzene ethylene glycol dimethacrylate, divinylbenzene ethylene glycol diacrylate, diethylene glycol dimethacrylate, diethylene glycol diacrylate, triethylene glycol dimethacrylate, triethylene glycol diacrylate , Trimethylolpropane trimethacrylate, trimethylolpropane triacrylate, tetramethylolmethane tetramethacrylate, tetramethylolmethane tetraacrylate, dipropylene glycol dimethacrylate Preparative and dipropylene glyco - diacrylate - DOO and the like, these may be used alone, or two or more kinds may be used in combination.

  The copolymerization amount bm of the polyfunctional monomer (b-2) in the acrylate-based crosslinked elastic particle (B) of the present invention is 100% by weight based on the monomer mixture (b-1). 0.1 to 5 weight% is preferable, 0.5 to 4 weight% is more preferable, and 0.8 to 3 weight% is still more preferable. When the copolymerization amount bm of the polyfunctional monomer is less than 0.1% by weight, the impact resistance and chemical resistance of the film that can be formed from the methacrylic resin composition tend to be lowered, and it exceeds 5% by weight. And there exists a tendency for impact resistance and the moldability of a film to fall.

  The methacrylic resin (C) used in the present invention is a two-layered polymer obtained by polymerizing a methacrylic ester polymer (A) in the presence of acrylate ester cross-linked elastic particles (B). is there. The acrylic ester-based crosslinked elastic particles (B) are obtained by copolymerizing two or more non-functional reactive double bonds (b-2) per molecule. The resulting polymer exhibits crosslinking elasticity. In addition, one reactive functional group (double bond) left unreacted during polymerization of the acrylic ester-based crosslinked elastic particles (B) becomes a graft crossover point, and a certain proportion of the methacrylate ester-based copolymer The coalescence (A) is grafted to the acrylate-based crosslinked elastic particles (B). Thereby, a resin composition in which the acrylic ester-based crosslinked elastic particles (B) are discontinuously and uniformly dispersed in the methacrylate ester-based copolymer (A) is obtained. On the other hand, for example, a methacrylic ester polymer (A), an acrylate ester cross-linked elastic particle (B), and a three-layer structure that polymerizes stepwise with a methacrylic ester polymer (A). In the polymer, the impact resistance of a film that can be formed from the resulting methacrylic resin composition is lowered.

In the methacrylic resin (C) of the present invention, a copolymerization amount bm of the polyfunctional monomer (b-2) in the acrylate-based crosslinked elastic particle (B) and a methacrylic resin (C described later) It is preferable that the following formula (i) is satisfied between the methyl ethyl ketone-soluble matter weight average molecular weight (Mw).
3 ≦ (Mw / 10000) / bm ≦ 8 (i)
When the value of (Mw / 10000) / bm is less than 3, the moldability of the film that can be formed from the methacrylic resin composition tends to decrease, and when it exceeds 8, the chemical resistance of the film tends to decrease. There is.

  The content of the acrylic ester-based crosslinked elastic particles (B) in the present invention is preferably 18 to 40% by weight, more preferably 18 to 38% by weight, when the entire methacrylic resin (C) is 100% by weight. Preferably, 18 to 35% by weight is more preferable. When the content of the acrylate ester-based crosslinked elastic particles (B) is less than 18% by weight, the impact resistance and moldability of the film that can be formed from the resulting methacrylic resin composition tend to be lowered. When slits are inserted to adjust the width, cracks tend to occur. When the content of the acrylate-based crosslinked elastic particles (B) exceeds 40% by weight, the hardness of the film, the moldability (the molding of the film itself) ) And processability (heat shrinkability) tend to decrease.

  The method for producing the methacrylic resin (C) in the present invention is not particularly limited, and a known emulsion polymerization method, emulsion-suspension polymerization method, suspension polymerization method, bulk polymerization method or solution polymerization method can be applied. An emulsion polymerization method is particularly preferred.

  As an initiator in the polymerization of the acrylic ester-based crosslinked elastic particles (B) of the present invention, known initiators such as organic peroxides, inorganic peroxides, and azo compounds can be used. Specifically, for example, t-butyl hydroperoxide, 1,1,3,3-tetramethylbutyl hydroperoxide, succinic acid peroxide, peroxymaleic acid t-butyl ester, cumene hydroper Organic peroxides such as oxide and benzoyl peroxide, inorganic peroxides such as potassium persulfate and sodium persulfate, and oil-soluble initiators such as azobisisobutyronitrile are also used. These may be used alone or in combination of two or more. These initiators include reducing agents such as sodium sulfite, sodium thiosulfate, sodium formaldehyde sulfoxylate, ascorbic acid, hydroxyacetone acid, ferrous sulfate, ferrous sulfate and disodium ethylenediaminetetraacetate It may be used as a combined ordinary redox initiator.

  The organic peroxide can be added by a known addition method such as a method of adding to a polymerization system as it is, a method of adding a mixture to a monomer, a method of adding a dispersion in an aqueous emulsifier solution, and the like. From the viewpoint of transparency, a method of adding a mixture to a monomer or a method of adding it by dispersing in an aqueous emulsifier solution is preferable.

  The organic peroxide is an organic reducing agent such as a divalent iron salt and / or formaldehyde sulfoxylate soda, reducing sugar, ascorbic acid or the like from the viewpoint of polymerization stability and particle size control. It is preferably used as a redox initiator in combination with a reducing agent. The surfactant used for the emulsion polymerization is not particularly limited, and any surfactant for normal emulsion polymerization can be used. Specifically, for example, anionic surfactants such as sodium alkyl sulfonate, sodium alkyl benzene sulfonate, sodium dioctyl sulfosuccinate, sodium lauryl sulfate, sodium fatty acid, alkylphenols, aliphatic alcohols, etc. And nonionic surfactants such as reaction products of olefins with propylene oxide and ethylene oxide. These surfactants may be used alone or in combination of two or more. Furthermore, if necessary, a cationic surfactant such as an alkylamine salt may be used.

  The average particle size of the obtained acrylic ester-based crosslinked elastic particle (B) latex in the present invention is preferably 0.04 μm to 0.3 μm, more preferably 0.04 μm to 0.25 μm, and 0.04 μm to 0 μm. More preferably, it is 2 μm. If the average particle diameter of the acrylate ester-based crosslinked elastic particle (B) latex is less than 0.04 μm, the impact resistance of the film that can be formed from the resulting methacrylic resin composition tends to decrease, and 0.3 μm If it exceeds, the transparency of the film tends to decrease.

  The weight average molecular weight (Mw) of the methyl ethyl ketone soluble part of the obtained methacrylic resin (C) in the present invention is preferably 50,000 to 120,000 (polystyrene conversion), more preferably 60,000 to 110,000, and more preferably 70,000 to 10 Ten thousand is more preferable. If the weight-average molecular weight (Mw) of the methacrylic resin (C) soluble in methyl ethyl ketone is less than 50,000, the chemical resistance of the film that can be formed from the resulting methacrylic resin composition tends to decrease. When it exceeds, there exists a tendency for the moldability of a film and a heat shrink rate to fall.

  Here, the weight average molecular weight (Mw) of the methyl ethyl ketone-soluble component of the methacrylic resin (C) is a value obtained by measuring a powder sample obtained by the following operation using a gel permeation chromatograph. That is, methacrylic resin (C) powder was added to 40 ml of methyl ethyl ketone, allowed to stand at room temperature for 12 hours, and then stirred for 30 minutes using a magnetic stirrer. This was centrifuged at 30000 rpm for 1 hour using a centrifuge (manufactured by Hitachi Koki Co., Ltd., classification centrifuge CP60E), and separated into a methyl ethyl ketone insoluble component and a soluble component (solution) by decantation. Further, 20 ml of methyl ethyl ketone was added to the methyl ethyl ketone insoluble matter, and centrifugation and decantation were repeated twice to separate the methyl ethyl ketone insoluble matter and the soluble matter. The methyl ethyl ketone soluble matter is precipitated with methanol with respect to the solution and dried at 60 ° C. for 10 hours using a vacuum dryer to obtain a powder soluble matter sample.

  The weight average molecular weight (Mw) of the methyl ethyl ketone soluble part of the obtained methacrylic resin (C) in the present invention can be controlled using a chain transfer agent during polymerization of the methacrylic ester polymer (A).

  The amount of the chain transfer agent used is preferably 0.3 to 2% by weight, more preferably 0.3 to 1.5% by weight, based on 100% by weight of the monomer mixture of the methacrylic ester polymer (A). Preferably, 0.3 to 1% by weight is more preferable. When the amount of the chain transfer agent used is less than 0.1% by weight, the moldability tends to decrease, and when it exceeds 5% by weight, the chemical resistance tends to decrease.

  The chain transfer agent is preferably selected from those usually used for radical polymerization, and specific examples include alkyl mercaptan having 2 to 20 carbon atoms, mercapto acids, thiophenol, carbon tetrachloride and the like. It is done. These may be used alone or in combination of two or more.

  From the obtained methacrylic resin (C) latex, the resin (C) is separated and recovered by ordinary coagulation, washing and drying operations, or by treatment such as spray drying or freeze drying.

  In the resin composition containing the methacrylic resin (C) of the present invention, polyglutarimide, glutaric anhydride polymer, lactone cyclized methacrylic resin, methacrylic resin, polyethylene terephthalate resin, polybutylene terephthalate resin are optionally included. Etc. can also be blended. The blending method is not particularly limited, and a known method can be used.

  In the resin composition containing the methacrylic resin (C) of the present invention, an inorganic pigment or an organic dye for coloring, an antioxidant, a heat stabilizer for further improving the stability to heat or light, You may add a ultraviolet absorber, a ultraviolet stabilizer, etc. or antibacterial, a deodorizing agent, a lubricant, etc. individually or in combination of 2 or more types. As the antioxidant, phenol-based, hindered phenol-based, hindered amine-based, phosphorus-based and sulfur-based antioxidants, heat stabilizers, and radical scavengers are preferably used. As the ultraviolet absorber, benzotriazole, benzophenone, salicylate, and triazine are preferably used, and benzotriazole and triazine are particularly preferable. Since the benzotriazole type has a large absorption at a long wavelength and the triazine type has a high absorption at a short wavelength, a synergistic effect can be expected by combining two or more kinds.

  The resin composition containing the methacrylic resin (C) of the present invention is satisfactorily processed by the T-die extrusion method.

  In the present invention, when forming a film, if necessary, by bringing both sides of the film into contact with a roll or a metal belt at the same time, in particular, simultaneously bringing into contact with a roll or metal belt heated to a temperature equal to or higher than the glass transition temperature. It is also possible to obtain a film having a superior surface property. In addition, depending on the purpose, film lamination and biaxial stretching can be used to modify the film.

  The film obtained from the resin composition of the present invention can reduce the gloss of the film surface by a known method, if necessary. For example, it can be carried out by a method of kneading an inorganic filler or crosslinkable polymer particles in a resin composition. Further, the gloss of the film surface can be reduced by embossing the obtained film.

  The thickness of the film obtained from the resin composition of the present invention is preferably 40 to 75 μm, more preferably 45 to 65 μm, and still more preferably 50 to 60 μm. If the thickness of the film is less than 40 μm, the moldability of the film is lowered and the long-term weather resistance tends to be lowered. If it exceeds 75 μm, the cost of the obtained film is increased, the productivity is lowered, and the transparency is lowered. There is.

  The film obtained from the resin composition of the present invention has a shrinkage rate of 21% or less when heat-treated in an atmosphere at 150 ° C. for 10 minutes. It is more preferably 20% or less, and further preferably 19% or less. When the shrinkage rate exceeds 21%, when a film obtained from a resin composition is laminated on a thermoplastic resin sheet by a thermal lamination method, the sheet curls on the film side or the film shrinks by heating and becomes shorter than the sheet. Productivity tends to decrease.

  In addition, in the resin composition of this invention, as mentioned above, the heat shrinkage rate of a film is controlled by making the weight molecular weight Mw of the methyl ethyl ketone soluble part in a methacrylic resin composition (C) into a specific range. can do.

  The film obtained from the resin composition of the present invention preferably has a weight change of 0.5% or less when immersed in DOP (di-2-ethylhexyl phthalate) for 7 days in an atmosphere at 23 ° C. % Or less is more preferable, and 0.3% or less is further preferable. When the weight change before and after DOP immersion exceeds 0.5%, when a film obtained from the resin composition is laminated on the vinyl chloride sheet, the methacrylic resin film becomes clouded by the plasticizer (DOP) blended in the vinyl chloride sheet. That is, the chemical resistance of the film tends to decrease.

  In the resin composition of the present invention, as described above, by controlling the copolymerization amount bm of the polyfunctional monomer (b-2) in the acrylate-based crosslinked elastic particle (B). The chemical resistance of the film can be improved.

  The resin composition of the present invention is pelletized by a single screw or twin screw extruder. The prepared pellets are formed into a film by a melt extrusion method using a T die. The lip opening degree (lip clearance) of the T die is preferably 0.2 to 0.5 mm, more preferably 0.3 to 0.5 mm. If it is 0.2 mm or less, the tip end of the die may come into contact with the scratch and it is not preferable. If it is 0.5 mm or more, the heat shrinkage rate is increased, which is not preferable.

  The mold temperature of the T die is preferably 210 to 270 ° C. If it is 210 ° C. or higher, the film thickness in the flow direction of the film is stable, and the heat shrinkage rate is preferably small. It is preferable because the die line can be suppressed.

  When the resin composition specified in the present invention is formed into a film having a specific thickness by the melt extrusion method, the heat shrinkability is excellent by setting the lip opening degree of the T die and the mold temperature within the above specific ranges. Film can be obtained.

  The amount of discharge when forming a film by the T-die melt extrusion method is preferably 100 to 400 kg, and particularly preferably 400 kg. If it is 400 kg or less, it is preferable because decomposition due to shear heat generation of the resin can be suppressed.

  The obtained film can be used by being laminated on a metal, plastic or the like. As a method of laminating the film, laminating such as multi-layer extrusion, laminating using a heating roll, wet laminating in which an adhesive is applied to a metal plate such as a steel plate, and then the film is placed on the metal plate and dried and bonded. And dry lamination, extrusion lamination, hot melt lamination, and the like.

  As a method of laminating a film on a plastic part, the film is placed in a mold and then placed in a mold after insert molding or laminate injection press molding in which resin is filled by injection molding, or after the film is preformed. In-mold molding in which resin is filled by injection molding can be used.

Film laminates obtained from the methacrylic resin composition of the present invention are used for coating substitutes such as automobile interior materials and automobile exterior materials, metal plating substitute films, solar cell backsheet films, solar cell surface protective films, mobile phones, personal computers. Used for housing surfaces, window frames, bathroom equipment, wallpaper, flooring and other building materials, household goods, furniture and electrical equipment housings, OA equipment housings such as facsimiles, and parts of electrical or electronic equipment be able to. In addition, as molded products, lighting lenses, automobile headlights, optical lenses, optical fibers, optical disks, liquid crystal light guide plates, liquid crystal films, medical supplies that require sterilization, microwave oven cooking containers, household appliance housings, It can be used for toys or recreational items.

  On the film obtained from the methacrylic resin composition of the present invention, a printing layer can be formed by a known printing method such as gravure printing method, flexographic printing method, silk screen printing method, etc. A pattern can be formed. In addition, a metal layer is formed on the film by using a metal such as aluminum, chromium, gold, silver, copper, nickel, cobalt, zinc, brass, and stainless steel by vacuum deposition, sputtering, or wet plating. can do. Alternatively, a metallic tone can be formed by laminating a metal foil-like material on a film via an adhesive layer or by heat fusion.

EXAMPLES Next, although this invention is demonstrated further in detail based on an Example, this invention is not limited only to these Examples.
In addition, each measuring method of the physical property measured in the following Examples and Comparative Examples is as follows.

(Evaluation of polymerization conversion)
The obtained methacrylic resin (C) latex was dried in a hot air dryer at 120 ° C. for 1 hour to determine the amount of solid components, and the polymerization conversion rate (%) was calculated by 100 × solid component amount / charged monomer (%). ) Was calculated.

(Evaluation of average particle diameter of latex)
The obtained methacrylic resin (C) latex was measured for volume average particle diameter (μm) by a light scattering method using MICROTRAC UPA manufactured by LEED & NORTHRUP INSTRUMENTS.

(Evaluation of weight average molecular weight)
The obtained methacrylic resin (C) powder was added to 40 ml of methyl ethyl ketone and allowed to stand at room temperature for 12 hours, and then stirred for 30 minutes using a magnetic stirrer. This was centrifuged at 30000 rpm for 1 hour using a centrifuge (manufactured by Hitachi Koki Co., Ltd., classification centrifuge CP60E), and separated into a methyl ethyl ketone insoluble component and a soluble component by decantation. Further, 20 ml of methyl ethyl ketone was added to the methyl ethyl ketone insoluble matter, and centrifugation and decantation were repeated twice to separate the methyl ethyl ketone insoluble matter and the soluble matter.
Methyl ethyl ketone soluble matter was precipitated with methanol and dried at 60 ° C. for 10 hours using a vacuum dryer to obtain a soluble matter sample. After 5 mg of the obtained soluble sample was dissolved in 2 ml of chloroform, the solution was filtered with a filter (DISMIC13JP050AN, manufactured by Advantech Toyo Co., Ltd.) attached to the tip of the disposable syringe. The polystyrene equivalent weight average molecular weight of this solution was measured using a gel permeation chromatograph (LC-6AD manufactured by Shimadzu Corporation, column: two K-806M manufactured by Shodex + guard column).

(Evaluation of transparency)
For the transparency of the obtained film, haze was measured in accordance with JIS K6714 under conditions of a temperature of 23 ° C. ± 2 ° C. and a humidity of 50% ± 5%.

(Evaluation of pencil hardness)
The pencil hardness of the obtained film was measured according to JIS S-1005.

(Evaluation of chemical resistance)
The obtained films were laminated and pressed at 200 ° C. × 50 kgf / cm 2 for 5 minutes to obtain a sheet having a thickness of 0.3 mm. The obtained sheet was cut into a 20 × 20 mm test piece. The obtained test piece was immersed in DOP (di-2-ethylhexyl phthalate), and allowed to stand in a 23 ° C. atmosphere for 7 days, and then the weight change was measured.
Weight change rate (%) = (weight after immersion−weight before immersion) / weight before immersion × 100

(Evaluation of formability)
Film formation with a thickness of 55 μm was carried out continuously for 3 hours, and the operating conditions were observed and evaluated according to the following criteria.
○: The film has a uniform thickness and can be formed without breakage. No cracks occur when slits are formed during film formation.
(Triangle | delta): Although the thickness of a film is uniform and it can shape | mold without cut | disconnecting, when a slit was put, the crack produced for a short time.
X: The film thickness was uneven or the film was cut, and cracks occurred when slits were inserted.

(Evaluation of film shrinkage)
The obtained film was cut into a disk shape having a diameter of 100 mm, and the dimension in the flow direction (MD direction) of the film after heating at 150 ° C. for 10 minutes was measured to determine the shrinkage rate.
Heat shrinkage rate (%) = (size in MD direction before heating (mm) −size in MD direction after heating (mm)) / size before heating × 100
For example, the heating shrinkage when the dimension in the MD direction after heating becomes 70 mm is calculated as (100 mm−70 mm) ÷ 100 × 100 = 30%.

In the production examples, examples and comparative examples, “parts” represents parts by weight and “%” represents% by weight. Abbreviations represent the following substances.
BA: butyl acrylate MMA: methyl methacrylate CHP: cumene hydroperoxide tDM: tertiary decyl mercaptan AlMA: allyl methacrylate (Production Example 1) Production of methacrylic resin composition Prepared.
Deionized water 200 parts Sodium dioctylsulfosuccinate 0.35 parts Sodium formaldehyde sulfoxylate 0.15 parts Ethylenediaminetetraacetic acid-2-sodium 0.004 parts Ferrous sulfate 0.001 parts Nitrogen in the polymerization machine After sufficiently substituting with gas and substantially free of oxygen, the internal temperature was set to 60 ° C., and the monomer mixture (B) shown in (1) in Table 1 [that is, BA 90 wt% and MMA 10 wt% 30 parts of a monomer mixture consisting of 2.0% by weight of AlMA and 0.2% by weight of CHP] is continuously added at a rate of 10 parts / hour to 100% by weight of the monomer mixture consisting of The polymerization was further continued for 0.5 hours to obtain acrylic ester-based crosslinked elastic particles (B). The polymerization conversion rate was 99.5%. Thereafter, 0.3 part of sodium dioctylsulfosuccinate was charged, the internal temperature was adjusted to 60 ° C., and the monomer mixture (A) shown in (1) in Table 1 [that is, BA 10 wt% and MMA 90 wt% 70 parts of a monomer mixture consisting of 0.6% by weight of tDM and 0.5% by weight of CHP] was continuously added at a rate of 10 parts / hour to 100% by weight of the monomer mixture comprising The methacrylic resin (C) was obtained. The polymerization conversion rate was 98.5%. The obtained latex was salted out with calcium chloride, coagulated, washed with water and dried to obtain a resin powder (1) of a methacrylic acid resin (C).

  To 100 parts of resin powder (1), 1.5 parts of benzotriazole-based UV absorber LA31 (manufactured by ADEKA), 0.5 part of triazine-based UV absorber Tinuvin 1577 (manufactured by Ciba Specialty Chemicals) and Tominox as an antioxidant TT (manufactured by API Corporation) 0.2 part was mixed, and the cylinder temperature was set to 120 ° C. using a vented 58 mmφ twin-screw single-screw extruder TEM58SS (Toshiba Machine). Except for the above, melt kneading was performed at 220 ° C., and extrusion was performed to obtain resin composition pellets 1.

(Production Examples 2-14)
Except for changing the monomer composition as shown in Table 1, polymerization is performed in the same manner as in Production Example 1, coagulation, washing with water and drying to obtain resin powders (2) to (14), followed by melt kneading, Pellets 2-14 were obtained. The characteristics of the methacrylic acid resin (C) are shown in Table 1.

(Examples 1-40, Comparative Examples 1-62)
The pellet obtained in the production example was set to 220 ° C. using a 40 mmφ extruder with a T-die, and the screen temperature was set to 220 ° C., and the screen mesh was 100 mesh, 400 mesh, 100 mesh, They were attached in the order of 40 mesh. The lip opening degree, the die temperature, and the discharge amount were set to the conditions shown in Tables 2 to 10, and the film was molded under the condition of the cooling roll temperature of 80 ° C. to obtain a film having a thickness of 55 μm.

  Tables 2 to 10 show the evaluation results of various properties using the used pellets and the obtained film.

Monomer composition ratio of methacrylic resin composition (C), layer structure, weight average molecular weight, average particle diameter and content of acrylate-based crosslinked elastic particles (B), and polyfunctionality in (B) When the copolymerization amount of the monomer, the opening degree of the lip at the time of molding, and the die temperature were outside the scope of the present invention, a film excellent in moldability and heat shrinkability could not be obtained. (Comparative Examples 22-62)
In addition, when the lip opening degree and the die temperature at the time of molding were out of the range of the present invention, a film excellent in heat shrinkability could not be obtained. (Comparative Examples 1-21)

Claims (3)

Two or more non-conjugated double bonds per molecule are added to a monomer mixture (total 100% by weight) (b-1) containing 50 to 100% by weight of acrylic acid alkyl ester and 0 to 50% by weight of methacrylic acid alkyl ester. In the presence of the acrylic ester-based crosslinked elastic particles (B) obtained by copolymerizing the polyfunctional monomer (b-2) having, a methacrylic acid alkyl ester 50 to 100% by weight and an acrylic acid alkyl ester 0 It consists of a resin composition containing a methacrylic resin (C) obtained by polymerizing a monomer mixture containing -50 wt% (total 100 wt%) and having the following characteristics (1) to (6): A methacrylic resin film having a film thickness of 40 to 75 μm and a heat shrinkage in the flow direction of the film after heating at 150 ° C. of 21% or less.
(1) The methacrylic resin (C) is a acrylate ester-based crosslinked elastic particle (B) and then a two-layer structure polymer that is a methacrylic ester polymer (A).
(2) In the acrylic ester-based crosslinked elastic particles (B), the polyfunctional monomer (b-2) is 0.1 to 5 with respect to 100% by weight of the monomer mixture (b-1). % Copolymerized,
(3) The weight average molecular weight (Mw) of the methyl ethyl ketone-soluble component of the methacrylic resin (C) is 50,000 to 120,000 (polystyrene conversion),
(4) The average particle diameter of the acrylic ester-based crosslinked elastic particles (B) is 0.04 μm to 0.3 μm,
(5) The content of the acrylic ester-based crosslinked elastic particles (B) is 18 to 40% by weight,
(6) The copolymerization amount bm and the weight average molecular weight Mw of the polyfunctional monomer (b-2) in the acrylate ester-based crosslinked elastic particles (B) satisfy the following formula (i).
3 ≦ (Mw / 10000) / bm ≦ 8 (i) 2. The methacrylic resin film according to claim 1, wherein, in the melt extrusion T-die method, the T die has a die opening degree of 0.2 to 0.5 mm and a die temperature of 210 to 270 [deg.] C. A methacrylic resin laminated sheet obtained by laminating a methacrylic resin film according to claim 1 or a methacrylic resin film molded by the molding method according to claim 2 on a thermoplastic resin sheet.