Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – From phenol – phenol ether – or inorganic phenolate
Reexamination Certificate
2001-03-22
2002-10-01
Boykin, Terressa M. (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
From phenol, phenol ether, or inorganic phenolate
C428S412000, C264S176100, C528S193000, C528S194000, C528S198000, C528S271000, C528S272000
Reexamination Certificate
active
06458913
ABSTRACT:
FIELD OF INVENTION
This invention relates to insert molded articles in which a substrate or film is back molded with an injection molded material.
BACKGROUND OF THE INVENTION
In a typical in-mold decorating process, a printed substrate is formed into a three-dimensional shape and placed into a mold. Molten resin is then injected into the mold cavity space behind the formed substrate, forming a single molded part.
IMD may involve two types of film processes. According to one process, the film is a permanent fixture of the finished good. In this case, the film can act as the aesthetic effect carrier, and/or as a protective layer for the substrate resin, the ink, or both. Good adhesion is required between the film, such as a polycarbonate type film, and the substrate resin.
According to another process, the film may be a temporary carrier for the aesthetic effect. In this case the substrate resin is back-molded on the IMD film and the film is subsequently peeled off of the substrate resin, leaving the aesthetic material/design behind on the substrate resin. Good adhesion is not desired between the film, which may be a poly(ethylene terephthalate) type film and the substrate resin.
For both in-mold decorating (IMD) applications, ink washout of the IMD film is an inherent problem. In IMD applications, an ink (or other aesthetic enhancement) bearing or containing film is back-molded by a substrate resin for structural support. During the back-molding of the substrate material, the aesthetic ink or effect material is often sandwiched between the IMD film and the substrate resin. The resulting shear from the back-molding injection of the substrate resin material against the IMD film, coupled with the heat of the molten substrate resin can often cause the ink (or aesthetic bearing material) to detach itself from the IMD film. This results in an area of decreased ink concentration, or “washout.” This washout is caused by several processing factors of the substrate resin, including processing temperature and injection shear.
Other challenges during the IMD process are foil breakage/wrinkling, again as a result of the high pressures and temperatures needed to back mold.
A resin used as an IMD substrate is a blend of polycarbonate (PC) with ABS (acrylonitrile-butadiene-styrene), such as Cycoloy produced by GE Plastics. One of the reasons is the superior shear thinning behavior of PC/ABS blends, which enables the molder to fill the mold at lower injection rates and temperatures.
U.S. Pat. No. 3,654,062 to Loew describes a molded decorative plaque having a laminated facing sheet which has the configuration of the mold. Heated plastic is injection molded behind the sheet to form the plaque. U.S. Pat. No. 6,117,384 to Laurin et al. describes a process where colors are decorated into a single film which is then incorporated with a molten resin injected behind the film to produce a permanently bonded three-dimensional piece. U.S. Pat. No. 4,391,954 to Scott describes a thermoplastic molding composition comprising an aromatic carbonate polymer and a polyester derived from a cyclohexanedimethanol. U.S. Pat. No. 4,125,572 to Scott describes a thermoplastic molding composition comprising an aromatic carbonate polymer and a polyester derived from an aliphatic or cycloaliphatic diol. U.S. Pat. No. 4,662,966 to Nissha Printing Co. Ltd. describes a transfer printing machine where designs of a diffusible dye on a transfer sheet is transferred to heated articles.
It is desired to have a material which has improved chemical resistance and can obtain low temperature impact with special effects and high clarity. The chemical resistance of many transparent, amorphous materials is not sufficient towards chemicals like oleic acid and/or coppertone, which are considered to be important chemicals in qualifying new materials in the telecom/electronics business. In some cases it is preferred to have a translucent material, since some light scattering can contribute to the desired effect.
SUMMARY OF INVENTION
A molded structure that comprises a decorative film or substrate, and an adjacent injection molded polymeric base comprising a substantially transparent cycloaliphatic polyester resin. In one embodiment, the substrate has at least one opening which exposes the transparent polymeric base resin to the exterior of the molded article.
According to a molding method, a printed substrate is formed into a three-dimensional shape and placed into a mold. Molten resin is then injected into the mold cavity space behind the formed substrate, forming a single molded part.
The use of a transparent cycloaliphatic polyester resin as the injection molded base material obviates disadvantages encountered with non-transparent PC/ABS type blends. Lack of transparency may be a significant drawback in certain applications. For instance, for some cell phones, a film (PET) with ink patterns is back molded with a transparent resin to mold the complete front cover. This is done so that information can be visually accessed by the product's user through a transparent window which is integrated into the structural resin of the product's design. During the back molding, ink may be transferred from the film to the transparent resin and then removed, resulting in a decorated front cover. An example of transfer printing the Nissha process. See U.S. Pat. No. 4,662,966 to Sumi et al.
For some applications, the film of substrate material may be a permanent aesthetic part of the finished product. For some wireless personal electronic applications which may use a film such as a polycarbonate (PC) film with ink patterns which is back molded with a transparent resin to mold the complete product housing. The transparent base material is molded to create a transparent window. Data may be transferred to/from the electronic product to its server by IR through the transparent window which is integrated into the structural resin of the product. Holes in the film expose the transparent injected molded base resin for either data transfer or aesthetic purposes.
One possibility for a transparent material is polycarbonate (PC). Typically, the processing temperature and injection shear (viscosity) of PC results in washout of ink on the IMD film at the injection gate. Other higher flow transparent materials (like LEXAN SP, a super high flow PC grade produced by GE Plastics) give an improvement in terms of viscosity, but have a very small processing window and as such are not very robust. Even these higher flow materials are not suitable for thinner-walled IMD parts where their fast injection speeds will still result in IMD washout and other issues as described above (e.g. foil breakage). In addition, physical properties (especially impact) of LEXAN SP and other such high-flow products are also not sufficient for use in many IMD applications.
Cycloaliphatic polyester/Polycarbonate blends and/or cycloaliphatic polyester/Polycarbonate/impact modified blends are utilized as a back-molded resin for in-mold decorated (IMD) film applications. Transparent blends of Polycarbonate (PC) and poly(cyclohexane dimethanol cyclohexane dicarboxylate) (PCCD) possess lower processing temperatures and improved flow characteristics over standard PC materials. This results in slower injection speeds and lower injection shear in an injection molded IMD part when compared to other transparent back-molding substrate resins (such as LEXAN SP) for in-mold decorating (IMD) applications. This in turn results in a decrease of the washout effect in IMD applications. These blends also offer superior chemical resistance and ductility to that of most transparent resin materials. The complete miscibility of this system allows the properties of the resulting blend to be dialed in, via blend ratio, while still maintaining transparency.
Two types of cycloaliphatic polyesters may desirable can be used with BPA-based polycarbonate to give the compositions and articles of this invention. The most preferred polyester molecules are derived from cycloaliphatic diol and cycloaliphatic diacid compou
Groothuis Adelbert Hermannus Leonardus
Honigfort Paul
Hoogland Gabrie
Laurin Michael M.
Boykin Terressa M.
General Electric Company
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