Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Compositions to be polymerized by wave energy wherein said...
Reexamination Certificate
2000-09-11
2002-07-16
Berman, Susan W. (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Compositions to be polymerized by wave energy wherein said...
C522S071000, C522S081000, C522S083000, C522S111000, C522S112000, C522S110000, C522S109000, C523S172000, C106S031010, C106S031350
Reexamination Certificate
active
06420449
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a resin composition for white marking which can form a white marking by irradiating laser beams, particularly, a resin composition which has not only excellent white-marking properties, but also a remarkable molding processability and impact resistance, and is available at an inexpensive price as well as recyclable. To be more specific, the present invention relates to a resin composition for white marking which is useful for a production of a molded article whose surface can be marked with recognizable or legible white letters or figures (e.g. key caps of a keyboard, button parts of a motorcar) by irradiating laser beams with a wavelength of, for instance, 1064 nm thereon.
BACKGROUND ART
It is a common practice to print letters, designs, figures and the like on the surface of a molded resin article. The printing is performed by a variety of known techniques, from those using paints such as pad printing and impregnation printing, to a printing technique by means of laser beam irradiation (hereinafter, mentioned as laser marking). Although the methods using a paint are most widely employed for such printing, the processes have disadvantages: high processing cost, fears of environmental pollution by solvents, less possibility of recycling, etc. On the other hand, laser marking is a cheaper and more efficient method than the painting techniques owing to its simple marking process. Laser marking ensures excellent durability of the printed materials, thus being highly valuable in industrial applications. As a result, many techniques have been suggested for laser marking. For instance, Japanese Patent Application Laid-Open No. 45926/1981 (JP-A-56-45926) teaches a technology for marking the surface of a molded resin article made of a resin blended with a filler discolourisable by laser beam irradiation.
An example of the molded articles to be printed with letters and figures by laser marking includes a keyboard of a personal computer. Main printing methods for the surface of a keyboard used to be pad printing onto an acrylonitrile-butadiene-styrene copolymer (an ABS resin) and impregnation printing onto polybutylene terephthalate (a PBT resin). However, in consideration of environmental problems inclusive of recycling as well as the factor of the cost, the marking method comprising irradiation of laser beams by using an Nd:YAG laser or other lasers on an ABS resin has been replacing the above processes.
On the one hand, a black or dark-coloured marking is generally effective on a molded article coloured in light gray, cream or other colours having a high brightness or lightness. On the other hand, the black-marking does not stand out on a black or dark-coloured article. In the case of the latter, letters and figures should be printed in white or a whitish colour (hereinafter, referred to as a white marking). However, it is usually impossible to develop a white marking on an ABS resin by irradiation of laser beams.
Japanese Patent Publication No. 47314/1990 (JP-B-2-47314) discloses a marking technique for resins. The technique comprises irradiating laser beams on the surface of a thermoplastic resin such as an acrylic resin, whereby the irradiated part foams and lifts up to form a white-marked section. As methods of making a white marking on the surface of resins, there are other known methods which comprise incorporating, into a resin, titanium black [Japanese Patent Application Laid-Open No. 81117/1988 (JP-A-63-81117), and Japanese Patent Application Laid-Open No. 25806/1996 (JP-A-8-25806)], cordierite and/or mica [Japanese Patent Application Laid-Open No. 267191/1992 (JP-A-4-26719/l)], aluminium hydroxide [Japanese Patent Application Laid-Open No. 25317/1993 (JP-A-5-25317)], and other inorganic compounds.
Moreover, Japanese Patent Application Laid-Open No. 120133/1996 (JP-A-8-120133) discloses a resin composition for white laser marking obtained by allowing an aromatic vinyl compound, a vinyl cyanide compound, a (meth)acrylate, maleic anhydride, maleimide and the like to polymerize in the presence of a rubber. This literature also describes the use of Titan Black, black iron oxide, yellow iron oxide or the like as a dye or pigment. Further, Japanese Patent Application Laid-Open No. 333503/1996 (JP-A-8-333503) discloses a resin composition for laser marking composed of the resin described in the above patent application [Japanese Patent Application Laid-Open No. 120133/1996 (JP-A-8-120133)], a flame retarder and a colouring agent such as Titan Black, carbon black and titanium white. In the Examples of these literatures, a rosined soap is used when producing resins.
However, the use of such resin compositions is still impractical in terms of the whiteness and quality of the marked letters and figures, and it is difficult to highly improve whiteness.
It is therefore an object of the present invention to provide a resin composition for white marking which can develop a clear white marking by irradiating laser beams and a molded article which is laser-markable in white formed with the resin composition.
It is another object of the present invention to provide a resin composition for white marking which can improve the whiteness of a mark without deteriorating the impact resistance of the molded article and a molded article which is laser-markable in white formed with the resin composition.
It is a further object of the present invention to provide a resin composition for white marking on which a marking can be made with high whiteness even when the irradiation energy intensity of laser beams is low and a molded article which is laser-markable in white formed with the resin composition, and a method for forming a white marking on the molded article.
A still further object of the present invention is to provide a resin composition for white marking which has good molding processability.
DISCLOSURE OF INVENTION
The inventors of the present invention have worked hard on the subject in order to achieve the above objects, and finally discovered that a molded article which is made of a resin composition containing a specific higher fatty acid or a derivative thereof can develop a remarkably distinct white marking in response to irradiation of laser beams. The present invention is based on the above findings.
In other words, the present invention provides a resin composition for white marking which comprises a thermoplastic resin, a non-terpene-series higher fatty acid or a derivative thereof and a black dye or pigment, and which can be marked in white by irradiation of laser beams.
The higher fatty acid or a derivative thereof may be a higher fatty acid having 12 to 30 carbon atoms or a metal salt of a saturated higher fatty acid. Moreover, the above resin composition may comprises an acrylic resin and a styrenic resin. The amount of the higher fatty acid or a derivative thereof is about 0.01 to 2 parts by weight relative to 100 parts by weight of the thermoplastic resin. The above resin composition may further comprise a non-black dye or pigment (e.g., a white dye or pigment such as titanium oxide).
As the acrylic resin, use can be made of, for example, a homopolymer or copolymer of a (meth)acrylic acid C
1-10
alkyl ester such as poly(methyl methacrylate). As the styrenic resin, use can be made of, for example, a rubber-modified styrenic resin such as an acrylonitrile-butadiene-styrene copolymer or a mixture of an acrylonitrile-butadiene-styrene copolymer and an acrylonitrile-styrene copolymer. As the black dye or pigment, use can be made of, for example, carbon black having a mean particle size of about 10 to 90 nm.
The present invention also includes a molded article formed with the above resin composition and a method for forming a white marking on the molded article.
Throughout the present specification, acrylic resins and methacrylic resins are generalized by the term “acrylic resin”. It should also be understood that acrylic acid and methacrylic acid may be generically called “(meth)acrylic acid”,
Imanishi Shinichiro
Sagane Hiroshi
Sumida Katsuhiko
Berman Susan W.
Birch & Stewart Kolasch & Birch, LLP
Daicel Chemical Industries Ltd.
LandOfFree
Resin composition for white marking does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Resin composition for white marking, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Resin composition for white marking will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2877615