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United States Patent m
Cozens et al.
 FROSTED POLYMERIC ARTICLES AND PROCESS FOR PRODUCING SAME
 Inventors: Ross J. Cozens, Strongsville; William S. Greenlee, Avon Lake; Douglas E. Skillicorn, Elyria, all of Ohio
 Assignee: The B. F. Goodrich Company,
[*] Notice: The portion of the term of this patent subsequent to Jul. 14, 2009 has been disclaimed.
 Appl. No.: 714,119
 Filed: Jun. 11, 1991
Related U.S. Application Data
 Continuation-in-part of Ser. No. 449,487, £>ec. 11, 1989, abandoned, which is a continuation of Ser. No. 99,818, Sep. 27, 1987. abandoned.
[ii] Patent Number: 5,247,019  Date of Patent: * Sep. 21, 1993
 U.S. CI 525/239; 524/515;
 Field of Search 525/239; 524/515, 525,
 References Cited
FOREIGN PATENT DOCUMENTS
0104433 8/1983 European Pat. Off. .
Primary Examiner—Paul R. Michl
Assistant Examiner—Edward Cain
Attorney, Agent, or Firm—Miles B. Dearth
Optically transparent frosted polymeric articles are disclosed which can be produced in smooth molds. Polymeric articles, such as PVC bottles, are molded from a composition having two polymers with different viscoelastic properties. A particularly desirable composition is one containing both PVC and crosslinked PVC.
32 Claims, 2 Drawing Sheets
Polymeric articles because of their inherent properties are replacing glass in many end use applications, such as bottles, packaging, containers, window panes, light covers, shower doors, and the like. Some of these applications are enhanced by a "frosted" look either for practical reasons such as to block sight through the material or for aesthetic reasons. Glass is normally made frosted by etching the surface of the glass to create a light scattering and thus the frosted look is achieved. Because many polymeries cannot withstand a mechanical etching process such as sandblasting, other methods must be used to achieve the frosted appearance. To create the frosted glass look in polymeric articles, those skilled in the art will etch the mold by sandblasting or other means to give a rough surface on the mold. The rough surface on the mold transfers to the moldable polymeric article, thus creating a frosted appearance.
The practice of altering the molds is an expensive process because the mold cannot be used again for nonfrosted articles. Many molding machines for polymeries have multi-cavity molds and thus several cavities must be altered. Injection blow molding is a common process used to produce bottles. The molds for this process cost from about $100,000 to $200,000, thus making the increased inventory of molds uneconomical. Also, some polymeric materials such as polyvinyl chloride (PVC), when injection blow molded into bottles, have a low pressure applied to the PVC during the molding process, such that the PVC would not be forced into the mold at sufficient pressure to transfer a small surface roughness to the PVC bottle. This explains the absence of frosted PVC bottles from the marketplace, even though they are desired by customers.
For the rare polymeric materials which can withstand a post molding treatment of etching, the post 45 molding treatment is an added process which adds greatly to the cost of the article.
It would be desirable to have a process which could produce frosted polymeric articles which did not involve etching the mold or an abrasive aftertreatment, and which could be molded in conventional smooth molds.
It is an object of the invention to provide frosted polymeric articles.
It is a further object of this invention to provide a process for producing these novel frosted polymeric articles.
It is an additional object of this invention to provide compositions which are suitable for the production of frosted polymeric articles.
These and other objects which will become evident from the following disclosure are accomplished by forming a polymeric article from a composition com- 65 prising a first polymeric component and a second polymeric component, wherein said first polymeric component and said second polymeric component have differ
ent viscoelastic properties. Preferably, the first polymeric component and the second polymeric component also have similar optical properties such as refractive index.
In the most preferred embodiment of this invention, the first polymeric component is a PVC polymer and the second polymeric component is a crosslinked PVC.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is an optical microscope photograph showing an extruded strip according to this invention made with the composition of Example 1, run 4. The microfracture or roughness of the surface is visible from the photograph. The scale of the photograph is 1 inch = 100 u.m.
FIG. 2 is an optical microscope photograph showing an extruded strip made with the composition of Example 1, run 1 (control). This sample is the same as FIG. 1 with the exception that FIG. 1 composition contains 20 weight parts of crosslinked PVC. The scale of the photograph is the same as in FIG. 1.
DETAILED DESCRIPTION OF THE
The polymeric materials used to produce the articles of this invention include polymeric materials such as polyvinyl chloride and optically transparent copolymers of polyvinyl chloride, polyester, polycarbonate, polystyrene, polymethyl methacrylate and the like. Any optically transparent polymer or polymer which can be rendered optically transparent by appropriate processing is useful in this invention. The term polymer includes oligomers, copolymers, terpolymers or higher order polymers of materials normally referred to as thermoplastic or elastomeric and blends thereof. The invention will be described in terms of a polyvinyl chloride article.
The frosted articles of this invention include articles such as bottles, packaging sheet, containers, window panes, light covers, shower doors, door panels, imitation glass block and the like. The invention will be described in terms of a frosted bottle but other articles could be made using this invention. The articles may be rigid or flexible depending upon the desired end use application.
The articles of this invention are optically transparent in the interior of the article but demonstrate limited light transmission due to a surface microfracture or roughness resulting from different viscoelastic properties of the article's polymeric components. This contrasts with a consistent haziness throughout an article produced with two polymeric materials, which when blended together, have different refractive indices.
The polymeric compositions used to produce the articles of this invention are optically transparent compositions. That is, the compositions are substantially free of pigments which block the transmission of light. The composition needs to be optically transparent in order to give an aesthetically appealing frosted look. With an optically transparent composition the frosted article has a sparkle appearance much like frosted glass. The compositions may, however, contain a tinting pigment, to give a color effect to the article while still allowing the article to transmit light.
The compositions may be rigid, semi-rigid or flexible. Rigid compositions are those which contain less than about 10 parts by weight of plasticizer per 100 parts by weight of polymer, other than the stabilizers, lubricants and processing aids. Likewise, semi-rigid compositions