Plastic and nonmetallic article shaping or treating: processes – Forming continuous or indefinite length work – Layered – stratified traversely of length – or multiphase...
Reexamination Certificate
2002-05-07
2003-11-18
Thibodeau, Paul (Department: 1773)
Plastic and nonmetallic article shaping or treating: processes
Forming continuous or indefinite length work
Layered, stratified traversely of length, or multiphase...
C264S173100, C156S244110
Reexamination Certificate
active
06649104
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to an acrylic resin film, a laminated film comprising the same and the use thereof.
BACKGROUND OF THE INVENTION
Molded articles produced by injection molding have been used as interior parts of automobiles, exterior parts of electric home appliances, and the like. For the decoration of such molded articles, a resin film having a decoration is laminated at the same time as the molding of the articles by simultaneous injection molding and lamination methods.
Simultaneous injection molding and lamination methods are such that a film inserted into a cavity between the male and female molds is unified with a molten resin injected into the mold cavity at the time of injection molding so as to apply the film on the surface of a molded article (see JP-B-63-6339 (U.S. Pat. No. 4,639,341), JP-B-4-9647 and JP-A-7-9484). Such molding methods may be referred to as lamination or transfer printing methods according to the different types of films used. Acrylic resin films are popular as films to be used in the simultaneous injection molding and lamination methods, and they have printed designs on one or both of their surfaces.
Acrylic resin films are also used for covering the surfaces of polycarbonate resin sheets, etc., since they have good weather resistance (see JP-B-47-19119 and JP-A-55-59929).
However, conventional acrylic resin films are unsatisfactory in thickness accuracy, surface smoothness, surface hardness, and the like.
Thus, the present inventors have made vigorous studies to develop an acrylic resin film having good thickness accuracy, surface smoothness and surface hardness at the same time. As a result, it has been found that a film made from a composition comprising an acrylic resin having a glass transition temperature of 60 to 110° C. and a weight average molecular weight of 70,000 to 600,000, and a multilayer-structured acrylic polymer containing an elastomeric layer has good thickness accuracy, surface smoothness and surface hardness, and further that an acrylic resin film and a laminated film comprising such an acrylic film are useful as lamination films for use in simultaneous injection molding and lamination methods, agricultural films, display films, masking films and paint-substitute films, and the like, and in particular, these films, which are colored or printed with designs, have the good printing properties of designs and can give added depth to the printed designs when the film is laminated on a molded article, in comparison with conventional acrylic resin films.
BRIEF SUMMARY OF THE INVENTION
The present invention provides an acrylic resin film made from a composition comprising 95 to 50 wt. parts of an acrylic resin having a glass transition temperature of 60 to 110° C. and a weight average molecular weight of 70,000 to 600,000, and 5 to 50 wt. parts of a multilayer-structured acrylic polymer containing an elastomeric layer. The present invention provides also a colored film comprising such an acrylic resin film, which can give added depth or a metallic color to a molded article, when the film is laminated on the article.
Furthermore, the present invention provides a laminated film comprising such an acrylic resin film and a film of other material such as a soft vinyl chloride resin.
The present invention provides a laminated molded article comprising a resin molded article of, for example, a polycarbonate resin, and such an acrylic resin film or such a laminated film which is laminated on the molded article.
In addition, the present invention relates to the use of such an acrylic film, a colored film or a laminated film, as an agricultural film, a display film, a masking film or a paint-substitute film.
The acrylic resin of the present invention should have a glass transition temperature of 60 to 110° C., preferably about 75 to 105° C., while acrylic resins generally have a glass transition temperature of about 30 to 110° C.
Herein, a glass transition temperature is measured using a differential scanning calorimeter (DSC) at a heating rate of 10° C./min. under a nitrogen stream, and a temperature at which an endothermic change starts is regarded as a glass transition temperature.
When the glass transition temperature is lower than 60° C., the acrylic resin film may not have sufficient surface hardness. An acrylic resin having a glass temperature of higher than 110° C. has a crosslinked structure, and is difficult to mold.
DETAILED DESCRIPTION OF THE INVENTION
The acrylic resin of the present invention should have a weight average molecular weight of about 70,000 to 600,000, preferably about 120,000 to 300,000. The weight average molecular weight of the acrylic resin is measured by any conventional method such as gel permeation chromatography (GPC), and the like.
When the weight average molecular weight of the acrylic resin is less than about 70,000, the processability of the resin deteriorates when the resin is molded in the form of a film, and sufficient thickness accuracy may not be attained. When the weight average molecular weight exceeds about 600,000, the molding of the resin in the form of a film becomes difficult, and gel-like materials tend to form in the film.
Examples of such acrylic resins include polyalkyl methacrylate resins, copolymers of an alkyl methacrylate and an alkyl acrylate, and the like. The copolymer of an alkyl methacrylate and an alkyl acrylate preferably comprises about 50 to 99 wt. % of the alkyl methacrylate and about 50 to 1 wt. % of the alkyl acrylate.
Examples of the alkyl methacrylate are methyl methacrylate, and the like. Examples of an alkyl group in the alkyl acrylate are alkyl groups having 2 to 10 carbon atoms. Specific examples of the alkyl acrylate are ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, hexyl acrylate, octyl acrylate, etc.
Such acrylic resins can be prepared by any known polymerization methods such as bulk polymerization and suspension polymerization methods.
The glass transition temperature of the acrylic resin can be controlled by the selection of the amounts and kinds of comonomers. The glass transition temperature increases, as the amount of a comonomer decreases, while the glass transition temperature decreases, as the molecular weight of a comonomer increases.
The weight average molecular weight of the acrylic resin can be adjusted by the selection of the kind and amount of a polymerization initiator, the kind and amount of a chain transfer agent, and a polymerization temperature.
The acrylic resin to be used in the present invention may be an as-produced resin containing no other polymer, or may be a mixture of two or more resins having different glass transition temperatures or different average molecular weights.
Acrylic resins having a glass transition temperature outside the range of about 60 to 110° C. or a weight average molecular weight outside the range of about 70,000 to 600,000 may be used, when their mixtures have a glass transition temperature of about 60 to 110° C. or a weight average molecular weight of about 70,000 to 600,000.
In particular, a resin mixture comprising at least one acrylic resin having a weight average molecular weight of about 70,000 to 200,000 is preferable from the viewpoint of the surface hardness of a film. Furthermore, a mixture comprising at least one acrylic resin having a weight average molecular weight of about 70,000 to 200,000 and at least one acrylic resin having a weight average molecular weight of about 150,000 to 700,000 is preferable, since unevenness of the film in the thermoforming of the film can be prevented, and the sufficient surface hardness is attained.
When a molecular weight distribution of such a resin mixture is analyzed on a chart obtained by GPC, a peak has a bottom-spreading shape, or is accompanied with a shoulder in relation to the molecular weight. The glass transition temperature of a resin having a weight average molecular weight of about 70,000 to 200,000 is preferably from about 90 to 110° C., while that of a resin having a weight a
Koyama Kouji
Mutou Kiyoshi
Tadokoro Yoshio
Ahmed Sheeba
Birch & Stewart Kolasch & Birch, LLP
Sumitomo Chemical Company Limited
Thibodeau Paul
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