JP2003073520A - Acrylic film and its laminate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a film causing little stress-whitening, having high surface hardness and rigidity and excellent in transparency when laminated on a plastic molding or the like. SOLUTION: This film is obtained by molding a resin composition comprising an acrylic graft copolymer and a methacrylic graft copolymer, wherein the content of acrylic ester-based rubber-like polymer is 5-20 wt.%, the average particle diameter of the acrylic ester-based rubber-like polymer is 500-2,000 Åand the relation between the average particle diameter d (Å) and the amount w (wt.%) of crosslinking agent used in the acrylic ester-based rubber-like polymer satisfies the formula 0.002d<=w<=0.005d, the graft rate of the acrylic graft copolymer is 30-200% and the reduced viscosity of the methyl ethyl ketone- soluble of the resin composition is 0.2-0.8 dl/g.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to specific acrylic films and acrylic film laminates, especially injection molded articles.

[0002]

2. Description of the Related Art As a method of decorating the surface of plastics, metal products, etc., there are a direct printing method and a transfer method. But,
The direct printing method is not suitable for molded products with complicated shapes,
The transfer method has a problem of high cost. As a method of giving decoration at low cost, in-mold molding in which a film such as acrylic resin is formed by vacuum molding in the previous step, or it is inserted into the injection molding die without molding and the base resin is injection molded. There is a law. Various acrylic films suitable for this use have been proposed. For example, JP-A-8-323934 describes the reduced viscosity of a plastic polymer, the particle size of a rubber-containing polymer, the rubber content, and the like. Further, JP-A-10-279766 and JP-A-10-306192 describe the reduced viscosity of the acrylic polymer and the content of the multi-layered acrylic polymer. It is described that these films have excellent surface hardness, transparency and film moldability. However, nothing is mentioned about stress whitening of the film. That is, in these applications, when a film is laminated on a molded product having a complicated shape in this application, stress concentrates on corners and the like, so that the film is liable to whiten and the commercial value is remarkably reduced.

[0003]

Therefore, the present inventors have found that
As a result of intensive studies to develop a film that does not cause stress whitening, a resin composition composed of a multi-layered acrylic polymer using a specific acrylic ester rubber elastic body and a methacrylic polymer shows that stress whitening does not occur. Low surface hardness, high transparency, excellent weather resistance, large elongation at break,
Furthermore, they have found that they are also excellent in film formability and surface properties, and have reached the present invention.

[0004]

Means for Solving the Problems The present invention comprises an acrylic graft copolymer (A) containing an acrylate rubber polymer and a methacrylic polymer (B) containing 80% by weight or more of methyl methacrylate. A resin composition comprising (1) an acrylic acid ester-based rubber-like polymer content of 5 to 20% by weight, and (2) an acrylic acid ester-based rubbery polymer having a particle size of 500 to 2000Å, ( 3) The relationship between the particle diameter d of the acrylic ester rubber-like polymer and the amount w of the crosslinking agent used in the acrylic ester rubber-like polymer satisfies the following equation: 0.002d ≦ w ≦ 0. 005d d: Å w: wt% (4) Graft ratio of the acrylic graft copolymer (A) is 30 to 200%, and (5) methyl ethyl ketone soluble component has a reversion viscosity of 0.2 to 0.8 dl / g. A resin composition It is an acrylic film formed by molding a product.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION The resin composition (C) used in the present invention contains 80% by weight or more of an acrylic graft copolymer (A) containing an acrylate rubber polymer and methyl methacrylate. It is composed of a methacrylic polymer (B) and an acrylic graft copolymer (A)
And the methacrylic polymer (B) are respectively polymerized to obtain a mixture thereof. In the production, the acrylic graft copolymer (A) is produced in the same reactor, and then the methacrylic polymer is produced. It is also possible to continuously produce (B). As a method for mixing, mixing in the form of latex, powder, beads, pellets or the like is possible. The acrylic graft copolymer (A) used in the present invention is obtained by polymerizing a (meth) acrylic acid ester monomer in the presence of a crosslinked rubbery polymer containing an acrylic acid ester as a main component. The acrylic acid ester-based rubbery polymer is preferably a monomer comprising 60 to 99% by weight of an acrylic acid ester, 0 to 30% by weight of another copolymerizable vinyl monomer, and a specific amount of a copolymerizable crosslinking agent. It is obtained by polymerizing a mixture. The monomers may be mixed and used, or the monomers may be used in two or more stages by changing the composition. As the acrylic acid ester used here, an alkyl group having 1 to 12 carbon atoms can be used from the viewpoint of polymerizability and cost. Specific examples thereof include methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, n-octyl acrylate, and the like, and these monomers are used in combination of two or more kinds. Good.

As the other copolymerizable vinyl monomer, methacrylic acid esters are particularly preferable from the viewpoints of weather resistance and transparency, and specific examples thereof include, for example, methyl methacrylate, ethyl methacrylate, propyl methacrylate. , Butyl methacrylate and the like. Further, aromatic vinyls, specific examples thereof include styrene and methylstyrene, and vinyl cyanides, specific examples thereof include acrylonitrile, methacrylonitrile and the like. The amount of the copolymerizable cross-linking agent has a great influence on the stress whitening, elongation at break, or transparency together with the average particle size of the acrylic ester polymer. That is, it is important that the average particle diameter (dÅ) and the amount of crosslinking agent (w% by weight) of the acrylic ester-based elastic material satisfy the following equation. 0.002d ≦ w ≦ 0.005d.

The rubbery polymer has an average particle size of 500Å to
It is 2000Å. Preferably 500Å ~ 1600Å,
It is more preferably 500Å to 1200Å, most preferably 600Å to 1000Å. If it is less than 500 Å, elongation at break, impact resistance, etc. are unfavorably lowered, and if it is 2,000 Å or more, stress whitening is likely to occur and transparency is unfavorable.

The amount of the cross-linking agent is preferably in the range represented by the above formula. Outside this range, stress whitening occurs, elongation at break decreases, transparency decreases, and film formability deteriorates. Is not preferable. The cross-linking agent used for this purpose may be a commonly used one, for example, allyl methacrylate, allyl acrylate, triallyl cyanurate, triallyl isocyanurate, diallyl phthalate, diallyl malate, divinyl adipate, divinylbenzene, ethylene glycol diethylene. Methacrylate, diethylene glycol dimethacrylate, triethylene glycol dimethacrylate, trimethylol propane trimethacrylate, tetromethylol methane tetramethacrylate, dipropylene glycol dimethacrylate and acrylates thereof can be used. You may use 2 or more types of these crosslinking agents.

The acrylic graft copolymer (A) is obtained by polymerizing a monomer containing methacrylic acid ester as a main component in the presence of the rubbery polymer. Preferably, it is obtained by polymerizing 95 to 25 parts by weight of a methacrylic acid ester in at least one stage in the presence of 5 to 75 parts by weight of the acrylic acid ester rubber polymer. At this time, a component which becomes an ungrafted polymer without grafting to the acrylic ester rubber elastic body is generated. This component constitutes part or all of the methacrylic polymer (B). The graft copolymer becomes insoluble in methyl ethyl ketone. Graft ratio of acrylic acid ester rubber is 30
˜200%, preferably 80 to 200%. If the graft ratio is 30% or less, the transparency may decrease,
The elongation is unfavorably reduced, and when it is 200% or more, the melt viscosity at the time of film formation becomes high and the film formability is deteriorated, which is not preferable. Examples of the monomer used in the graft reaction include methacrylic acid ester and acrylic acid ester, and specific examples thereof include those used for the acrylic acid ester-based rubber elastic body. The use ratio of the methacrylic acid ester is preferably 50% by weight or more. When the content is 50% by weight or less, the hardness and rigidity of the obtained film decrease, which is not preferable. The methacrylic polymer (B) used in the present invention contains 80% by weight or more of methyl methacrylate as a polymerization component. When the amount of methyl methacrylate is 80% by weight or less, the hardness and rigidity of the obtained film are reduced, which is not preferable.

The content of the acrylic rubber elastic body of the resin composition (C) of the present invention is preferably 5 to 20% by weight, and 10 to 10% by weight.
20% by weight is more preferred. If it is 5% by weight or less, the elongation of the obtained film is lowered and stress whitening is likely to occur, which is not preferable. When it is 20% by weight or more, the hardness and rigidity of the obtained film are lowered, which is not preferable. The reduced viscosity of the methyl ethyl ketone soluble component of the resin composition (C) of the present invention is 0.2 to 0.8 dl / g. When it is 0.2 dl / g or less, the elongation of the obtained film is lowered and the solvent resistance is lowered, which is not preferable, and when it is 0.8 dl / g or more, the film formability is lowered, which is not preferable. The method for producing the acrylic graft copolymer (A) and the methacrylic polymer (B) of the resin composition (C) of the present invention is not particularly limited, and it may be an emulsion polymerization method, a suspension polymerization method, a bulk polymerization method. The legality etc. can be applied.

In the emulsion polymerization method, a usual polymerization initiator is used. Specific examples include inorganic peroxides such as potassium persulfate and sodium persulfate, organic peroxides such as cumene hydroperoxide and benzoyl peroxide, and oil-soluble initiators such as azobisisobutyronitrile. used. These may be used alone or in combination of two or more. These initiators may be used as a usual redox type polymerization initiator in combination with a reducing agent such as sodium sulfite, sodium thiosulfate, sodium formaldehyde, sulfoxylate, ascorbic acid and ferrous sulfate. The surfactant used in the emulsion polymerization is not particularly limited, and any ordinary surfactant for emulsion polymerization can be used. For example, sodium alkyl sulfate, alkylbenzene sodium sulfonate,
Anionic surfactants such as dioctyl sodium sulfosuccinate and sodium laurate, and nonionic surfactants such as reaction products of alkylphenols and ethylene oxide are shown. These surfactants may be used alone or in combination of two or more. From the polymer latex obtained from such a copolymer, the resin composition is separated and recovered by usual coagulation and washing, or by treatment such as spraying and freezing.

The acrylic ester resin composition of the present invention is particularly effective as a film. For example, it is possible to use an ordinary melt extrusion method such as an inflation method, a T-type die extrusion method, a calendar method, or a solvent casting method. Processed well. The thickness of the film is 30 to 50
About 0 μm is suitable, and 50 to 300 μm is more preferable.

If necessary, the resin composition (C) can be fused at the temperature of the glass transition temperature or more at the same time on both sides of the film with a roll or a metal belt to obtain a film having a better surface property. is there.

The resin composition (C) of the present invention contains an inorganic or organic pigment for coloring, a dye, an antioxidant for further improving the stability to heat and light, a heat stabilizer, and an ultraviolet absorber. The agent, the ultraviolet stabilizer and the like may be added alone or in combination of two or more kinds.

[0015]

EXAMPLES The present invention will be described below with reference to examples. In addition, "part" in an Example and a reference example represents a weight part, and "%" represents a weight%. The abbreviations are as follows.

OSA: Sodium dioctyl sulfosuccinate BA: Butyl acrylate MMA: Methyl methacrylate CHP: Cumene hydroperoxide tDM: Tertiary dedyl mercaptan EA: Ethyl acrylate.

The characteristics and evaluations were according to the following methods and conditions.

An average particle size film of an acrylic ester rubber elastic body was dyed with ruthenium and observed with a transmission electron microscope to measure 500 particle sizes.

Graft ratio (G) The powder produced in Reference Example was dissolved in methyl ethyl ketone and separated into an insoluble component and a soluble component, and the insoluble component was determined as a graft component by the following formula.

G = (weight of insoluble matter-weight of rubber elastic body /
Weight of rubber elastic body) × 100.

The reduced viscosity film was dissolved in methyl ethyl ketone, and the soluble content was measured with 0.3% N, N-dimethylformamide at 30 ° C. Unit: dl / g.

Tensile strength and elongation at break The film was punched out into a JIS No. dumbbell and measured at 23 ° C. with an autograph at a tensile speed of 50 mm / min. Unit: Tensile strength is MP and elongation at break is%.

The cloud value was measured according to JIS K6714 using a transparent film. unit:%.

Pencil hardness It measured according to JISK5400 using the film.

Film Formability Film formation was carried out for 3 hours, the condition was observed, and the following evaluation was made. ◯: The film has a uniform thickness and can be molded without being cut. ×: The film has a non-uniform thickness or film breakage occurs.

Film surface property The surface of a film having a width of 1 m ² was observed and evaluated as follows. ◯: Almost no fish eye, dylan or scorch was observed. Δ: Any of fish eye, dylan or scorch was observed. X: Any of fish eye, dylan or scorch was remarkable.

Stress whitening The film was bent 180 ° at 23 ° C., and the whitening state was observed to make the following evaluations. ◯: No whitening is observed Δ: Whitening is slightly observed ×: Whitening is remarkable

Reference Example 1 The following substances were charged in an 8 L polymerization machine equipped with a stirrer.

Water 200 parts OSA 0.2 parts Ethylenediaminetetraacetic acid-2-sodium 0.001 part Ferrous sulfate 0.00025 parts Sodium formaldehyde sulfoxylate 0.15 parts After deoxidation, the internal temperature is 60 ° C. After that, the mixture (a) shown in Table 1 was continuously added dropwise at a rate of 10 parts / hour, and then post-polymerization was performed for 30 minutes to obtain an acrylic acid ester-based elastic body. The polymerization conversion rate was 99.5%. Then, after charging 0.2 part of sodium octyl sulfosuccinate, the mixture (b) shown in Table 1 was continuously added dropwise at a rate of 12 parts / hour, followed by 1 hour of post-polymerization to obtain an acrylic system. Graft copolymer (A) and methacrylic polymer (B)
Got Polymerization conversion rate is 99.0%, graft rate is 135
%, The reduced viscosity of the methyl ethyl ketone soluble component is 0.35d
It was 1 / g. The obtained latex was salted out with calcium acetate, coagulated, washed with water and dried to obtain a resin powder. The reduced viscosity and the graft ratio were measured and shown in Table 1.

Reference Examples 2 to 9 Reference Examples 2, 3, 4, 5,
6, 7, 8 and 9 were also produced according to the formulations shown in Table 1 in the same manner as in Reference Example 1. The reduced viscosity and the graft ratio were measured and shown in Table 1.

[0031]

[Table 1] (Reference Example 10) Similarly, by emulsion polymerization, MMA 92%, BA8
Copolymers were prepared with% monomer. The reduced viscosity of the obtained methacrylic acid ester-based copolymer is 0.36 dl.
/ G.

Reference Example 11 MMA produced by suspension polymerization
-EA copolymer (Sumipex E manufactured by Sumitomo Chemical Co., Ltd.
X: a polymer composed of MMA about 95% and EA about 5%, reduced viscosity 0.30 dl / g) was used.

(Examples 1 to 7 and Comparative Examples 1 to 5) Using 100 parts of the resin composition shown in Table 2 using the obtained polymers,
As a UV absorber, 1.5 parts of Tymbin 1577 (manufactured by Ciba Special Chemical Co., Ltd.) and 0.3 part of Sumilizer GM (manufactured by Sumitomo Chemical Co., Ltd.) as antioxidants are mixed and extruded at 220 ° C. with a vent type extruder. Got The obtained pellets were molded with a T-die extruder at a die temperature of 240 ° C. to obtain a film having a thickness of 100 μm. Various physical properties were evaluated using this film. The results are shown in Table 2.

[0034]

[Table 2]

[0035]

It can be seen that the film of the present invention has a good balance of tensile strength, elongation at break, stress whitening, transparency, surface height and surface property.

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 4F071 AA33 AA77 AA88 AE02 AF14                       AF25 AF30 BA01 BB06 BB09                       BC01                 4F100 AB01 AK01 AK25A AL01A                       AL05A AN02A AT00B BA02                       CA02A EH362 HB00 JK02                       JN01                 4J002 BG051 BN122 GF00

Claims (3)

[Claims] 1. A resin composition comprising (A) an acrylic graft copolymer containing an acrylate rubber polymer and (B) a methacrylic polymer containing 80% by weight or more of methyl methacrylate. And (1) the content of the acrylic ester rubber polymer is 5 to 20% by weight,
(2) The average particle size of the acrylic acid ester-based rubbery polymer is 500 to 2000Å, (3) the average particle size d (Å) of the acrylic acid ester-based rubbery polymer and the acrylic acid ester-based rubbery polymer The relationship with the amount w (% by weight) of the cross-linking agent used satisfies the following formula: 0.002d ≦ w ≦ 0.005d d: Å w:% by weight (4) Graft of acrylic graft copolymer (A) A film formed by molding a resin composition having a ratio of 30 to 200% and a reduced viscosity of (5) the methyl ethyl ketone soluble component of the resin composition of 0.2 to 0.8 dl / g. 2. A laminated product obtained by laminating the film according to claim 1. 3. An acrylic laminated product, wherein the laminated product according to claim 2 is manufactured by injection molding.