Stock material or miscellaneous articles – Composite – Of polycarbonate
Reexamination Certificate
2000-03-16
2003-01-21
Mullis, Jeffrey (Department: 1711)
Stock material or miscellaneous articles
Composite
Of polycarbonate
C428S483000, C428S500000, C428S515000, C428S517000, C428S523000, C525S085000
Reexamination Certificate
active
06509097
ABSTRACT:
TECHNICAL FIELD
The present invention relates to an acrylic film having a good processability and to an acrylic laminate obtained by laminating and bonding the film.
BACKGROUND ART
Acrylic resins, particularly methyl methacrylate-based resins, are known as resins excellent in both a transparency and a weather resistance and are in wide use for cast moldings, extrusion moldings and the like. However, these methyl methacrylate-based resins are generally brittle and have not been suited for use as film or sheet materials. Accordingly, a number of attempts have been made to obtain a composition for film which is improved in a flexibility and can be used as film or sheet materials. Such attempts include, for example, the use of a multilayer structure polymer as described in U.S. Pat. No. 4,508,875, A and a development of a blend with an acrylic rubber as described in JP-B-6-45737. The above-mentioned compositions for film had problems in that though a Tg of a polymer which forms a matrix (hereinafter referred to as matrix Tg) is relatively high and the resulting film shows elongation at break of about 100% and thereby the film can be satisfactorily used for conventional protective films, the film cannot bend and gets broken when the film is subjected to a bending work with a small radius of curvature or a bending work at a high speed. Thus, the compositions have been restricted in their use. Further, when the matrix Tg is simply lowered, a resistance to solvents and a resistance to hot-water whitening become poor and moreover a film-forming property becomes poor to make a satisfactory film preparation difficult, as described in JP-B-62-19309.
DISCLOSURE OF THE INVENTION
The present inventors have made extensive study to solve the above-mentioned problems. In result, it has been found that by selecting the matrix Tg at 65° C. or less, increasing a weight average molecular weight thereof to 100,000-300,000 more than that of a previous one and increasing a gel content of a film composition to 50-70% by weight, elongation at break can be increased to as high as 180% or more without a deterioration of a solvent resistance and a film-forming property, further that a resistance to hot-water whitening can be improved by adding 0.5-5 parts by weight of a polyalkylene glycol, and that when elongation at break of the film is 180% or more, the film can bend with a small radius of curvature and at a high speed and resultantly the film has a tendency not to break at the work.
Thus, the points of the present invention are an acrylic film comprising 70 to 95 parts by weight of (A) an acrylic rubber-containing polymer and 5 to 30 parts by weight of (B) an acrylic-based thermoplastic polymer and having a total amount of (A) the acrylic rubber-containing polymer and (B) the acrylic-based thermoplastic polymer of 100 parts by weight, a gel content of 50 to 70% by weight, and elongation at break in one direction of 180% or more,
wherein (A) the acrylic rubber-containing polymer comprises an elastic copolymer comprising 50 to 99.9% by weight of an alkyl ester of an acrylic acid monomer unit, 0 to 49.9% by weight of other copolymerizable vinyl monomer unit, and 0.1 to 10% by weight of a copolymerizable crosslinkable monomer unit, and a monomer or a mixture thereof comprising 40 to 100% by weight of an ester of a methacrylic acid and 0 to 60% by weight of a vinyl monomer copolymerizable therewith, wherein a glass transition temperature of a polymer of the monomer or the mixture exceeds 65° C.; (A) the acrylic rubber-containing polymer has a gel content of at least 60% by weight, a graft rubber particle diameter of 0.08 to 0.16 &mgr;m, and a calcium content of 50 to 500 ppm; and at least 10% of 10 to 400 parts by weight of the monomer or the mixture is bonded to and is graft-polymerized onto 100 parts by weight of the elastic copolymer, and
wherein (B) the acrylic-based thermoplastic polymer comprises 50 to 100% by weight of an ester of a methacrylic acid monomer unit having an alkyl group of 1 to 4 carbon atoms, 0 to 50% by weight of an ester of an acrylic acid monomer unit, and 0 to 50% by weight of at least one other copolymerizable vinyl monomer unit; and (B) the acrylic-based thermoplastic polymer has a glass transition temperature of 65° C. or less and a weight average molecular weight of 100,000 to 300,000, and
an article obtained by laminating the acrylic film.
BEST MODE FOR CARRYING OUT THE INVENTION
The acrylic rubber-containing polymer (A) used in the present invention is a graft copolymer having a multilayer structure of two or more layers which contains an acrylic acid alkyl ester monomer unit as a main component of the rubber and has a function of imparting an excellent impact resistance and elongation to a resin composition.
The acrylic rubber-containing polymer (A) used in the present invention may be obtained by copolymerizing a monomer mixture comprising 50-99.9% by weight of an acrylic acid alkyl ester monomer unit, 0-49.9% by weight of a copolymerizable other vinyl monomer unit and 0.1-10% by weight of a copolymerizable crosslinkable monomer unit in one or more stages to obtain an elastic copolymer, and then, in the presence of 100 parts by weight of the elastic copolymer obtained above, polymerizing 10-400 parts by weight of a monomer or a mixture thereof comprising 40-100% by weight of a methacrylic acid ester and 0-60% by weight of a vinyl monomer copolymeriable therewith, a polymer of the monomer or the mixture thereof having a glass transition temperature more than 65° C., in one or more stages. When a content of the acrylic acid alkyl ester monomer unit in the elastic copolymer is less than 50% by weight, a sufficient flexibility cannot be imparted to the film. The presence of a layer whose acrylic acid alkyl ester monomer unit content is less than 50% by weight as a core inside the elastic copolymer is allowable so long as the acrylic acid alkyl ester monomer unit content in the elastic copolymer as a whole, including the core layer, is 50% by weight or more. When a content of the crosslinkable monomer unit is less than 0.1% by weight, a sufficient crosslinking effect cannot be obtained; when the content exceeds 10% by weight, the resulting elastic property is deteriorated.
The acrylic acid ester which may be used herein is an acrylic acid alkyl ester having an alkyl group of 1-8 carbon atoms, for example, methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, 2-ethylhexyl acrylate and n-octyl acrylate etc., used each alone or as a mixture thereof. One having a low Tg is preferable, butyl acrylate being most preferred. The copolymerizable vinyl monomer may be conventional ones, which include, for example, acrylic or methacrylic acid higher alkyl esters, acrylic or methacrylic acid lower alkoxy esters, acrylic or methacrylic acid cyanoethyl ester, acryl- or methacrylamide, acrylic or methacrylic acid, styrene, alkyl-substituted styrenes, acrylonitrile, methacrylonitrile, maleic acid, fumaric acid and vinyltoluene etc., but they are not limited thereto. The methacrylic acid esters used are preferably methacrylic acid alkyl esters having an alkyl group of 1-4 carbon atoms, e.g., methyl methacrylate, ethyl methacrylate, propyl methacrylate and butyl methacrylate etc., used each alone or as a mixture thereof.
The crosslinkable monomers are not particularly resistricted but are preferably ethylene glycol dimethacrylate, butanediol dimethacrylate, allyl acrylate, allyl methacrylate, diallyl phthalate, triallyl cyanurate, triallyl isocyanurate, divinylbenzene, diallyl maleate, trimethylol triacrylate and allyl cinnamate; they may be used each alone or in a combination of two or more thereof.
Of the acrylic rubber-containing polymer (A), a multilayer structure polymer (AA) described below is particularly preferable because it gives a better resistance to bending whitening.
Monomer compositions used in the multilayer structure polymer (AA) used in the present invention are as follows. The acrylic acid alkyl esters having an alkyl group of 1-8 carbon atoms and the methacrylic ac
Hatakeyama Hiroki
Hayashida Kazuaki
Kitaike Yukio
Mitsubishi Rayon Co. Ltd.
Mullis Jeffrey
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