Stock material or miscellaneous articles – Web or sheet containing structurally defined element or... – Including a second component containing structurally defined...
Reexamination Certificate
1996-08-05
2004-06-15
Juska, Cheryl A. (Department: 1771)
Stock material or miscellaneous articles
Web or sheet containing structurally defined element or...
Including a second component containing structurally defined...
C428S323000, C428S297400, C428S300400, C264S241000, C264S246000, C264S445000
Reexamination Certificate
active
06749932
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATIONS
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
Not applicable
BACKGROUND OF THE INVENTION
This invention relates to colourants, including colourants for incorporation in plastics materials, to coloured articles made from plastics materials which incorporate such colourants, and to methods of making such colourants and articles.
Plastics articles made by moulding, casting, extrusion, calendering and suchlike processes are well-known. Such articles may be thermoplastic or thermoset. It is often desirable that the surface of such plastics articles should have a decorative visual effect. Plastics materials which contain colourants such as dyes (i.e. coloured substances dispersed at the molecular level) and/or pigments (i.e. coloured particles up to about 1 micron in size) are well-known. Commonly, such colourants are uniformly dispersed throughout the plastics material, and the plastics material and articles made therefrom are uniformly coloured. Pigment particles scatter light as a consequence of their small size, and as a result pigmented plastics materials are generally opaque. Pure plastics materials are often transparent and remain transparent when dyed. Inert fillers can be included in such dyed materials to provide translucency or opacity. The visual appearance of the surface of such dyed or pigmented plastics materials is generally flat and lacking in depth and texture.
Plastics materials which incorporate particles of visual size (for example, having a minimum dimension of about 5 micron) dispersed therein, for example fibres, flakes or grits (spherical, roughly spherical, or more or less irregular particles), are known. Fibres may be incorporated in a plastics matrix to provide mechanical reinforcement. Grits may be incorporated in a plastics matrix to provide abrasion resistance. If the colour of such particles differs from that of the plastics matrix in which they are incorporated, such plastics materials may have a speckled or mottled appearance, and such particles have on occasion been incorporated for the purpose of providing a decorative surface effect.
BRIEF SUMMARY OF THE INVENTION
The invention provides an article having a decorative visual surface appearance provided by a plastics composition which comprises a transparent or translucent plastics material having a colourant dispersed therein, characterised in that the colourant comprises a blend of discrete polymer particles substantially all of which have a minimum dimension in the range 5 to 100 micron and a maximum dimension of no more than 10 mm, said particles being of a natural or synthetic organic polymer or a glass, the blend comprising particles of at least two distinct colours and/or shapes, and the plastics composition containing 0.1 to 8 per cent by weight of the blend of polymer particles based on the weight of the plastics composition.
It will readily be understood that the term “substantially all” is synonymous with “largely or wholly” or “a substantial majority”. For example at least 90 or at least 95 or 100 percent of the particles may be of the specified dimensions.
It will be appreciated that the decorative appearance of the articles of the invention is provided by the colourant within the plastics composition and is independent of any feature of shape or form of the article. The surface of such articles may be smooth, patterned or shaped, but is solid and continuous. It will further be appreciated that the portion of the article which incorporates the colourant may be overlaid by a transparent or translucent layer through which the coloured plastics composition can be seen.
The invention further provides a method of making a plastics article including the steps of:
(a) mixing together (i) a colourant which comprises a blend of discrete polymer particles substantially all of which have a minimum dimension in the range 5 to 100 micron and a maximum dimension of no more than 10 mm, said blend comprising particles of at least two distinct colours and/or shapes, and (ii) a transparent or translucent plastics material or a precursor thereof, and
(b) forming said article under conditions whereby said polymer particles are not permanently deformed to any substantial extent.
The invention further provides a colourant in the form of a colour concentrate which comprises discrete coloured particles homogeneously mixed with a polymer or precursor thereof or a wax, characterised in that substantially all of the particles are polymer particles which have a minimum dimension in the range 5 to 100 micron and a maximum dimension of no more than 10 mm, which polymer particles are of at least two distinct colours and/or shapes. The colourant-of the invention may take the form of a masterbatch material wherein the coloured particles are homogeneously mixed with a thermoplastic resin binder.
The decorate surface layer of a plastics article according to the invention has an unusual and attractive dappled appearance with remarkable visual depth and texture. The article surprisingly has this appearance even when, as is desirable, the colourant is well mixed with the plastics material so that it is uniformly dispersed therein. Such a decorative surface layer may if desired be designed to mimic natural materials, for example various types of stone or rock, including sedimentary, igneous and in particular metamorphic rock such as slate. Other examples of such natural materials include leather and wood.
The polymer particles in the colourant may take the form of fibres, flakes, spheroids or grits or mixtures thereof. It may be preferred that substantially all the polymer particles have a maximum dimension in the range 0.5 to 10 mm. Preferred fibres may have a titre in the range 1 to 30 decitex, often 1 to 6 decitex, and a length in the range 0.5 to 10 mm or 0.1 or 0.25 to 10 mm. Such fibres are commonly referred to as staple fibres and may also be referred to as flock, particularly when they have a length below about 5 mm. Fibre flock may be prepared by cutting longer fibres to lengths of about 0.25 mm or above. Shorter flock may be prepared by grinding, for example cryogenic grinding. Preferred flakes may have a basis weight in the range 10 to 50 grams per square meter in the plane of the flake and maximum dimensions in the range 0.5 to 5 mm or 0.1 or 0.25 to 5 mm. Suitable flakes may be prepared for example by chopping or grinding shredding (including cryogenically grinding) a polymer film. Preferred spheroids include polymer beads and glass beads. It will be appreciated that the particles should desirably be of a shape and composition such that they do not damage the processing equipment, for example by abrasion. Accordingly, the use of glass powder or flake may generally be less favoured, as compared with glass fibre and beads, in extrusion and suchlike techniques.
The particles may consist essentially of a natural organic polymer, a synthetic organic polymer or glass. They may consist essentially of a natural polymer which has been processed, for example they may consist essentially of cellulose in the form of regenerated viscose. Use of synthetic organic polymers or processed natural organic polymers may be preferred. Use of glass particles may alternatively be preferred in some applications. Examples of suitable types of glass include A-, C-, E- and S-glass. Each polymer particle usually contains a single type of polymer but may contain a mixture of more than one type of polymer. The particles within the blend may consist of the same or different types of polymer or polymer mixture. The material of the polymer particles should be chosen having regard to compatibility between this material and the plastics material in which the particles are to be incorporated. A specific type of polymer particle is unplasticised cellulose film, optionally pigmented, for example regenerated cellulose film such as that made by the viscose process, which has been reduced to the specified size and optionally dyed.
The polymer particles are preferably both mechanically and therm
Juska Cheryl A.
Quarles & Brady LLP
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