Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – At least one aryl ring which is part of a fused or bridged...
Reexamination Certificate
2001-10-25
2003-11-11
Cain, Edward J. (Department: 1714)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
At least one aryl ring which is part of a fused or bridged...
C524S437000, C524S489000
Reexamination Certificate
active
06646038
ABSTRACT:
FIELD OF INVENTION
The present invention concerns a color concentrate for use in coloring plastics. More particularly, the present invention concerns a metal containing thermoplastic color concentrate for use in imparting a metallic effect or appearance to the thermoplastic polymer that is being colored.
BACKGROUND
Thermoplastic polymers are often colored in the molten state by the addition of color concentrates. Color concentrates are concentrated dispersions of a colorant in a carrier polymer. The carrier polymer being either the same as or compatible with the polymer to be colored. Color concentrates are generally used to ensure good dispersibility and incorporation of pigments and other additives. Use of color concentrates can also create a much cleaner environment for an end user, for an end user does not have to involve oneself with dusty pigments and other hard to handle materials.
There are several methods for adding a color concentrate to a thermoplastic polymer that is to be colored. However, the most common method utilized today involves the controlled metering of the color concentrate into the throat of a polymer extruder using pellet feeders. In this application, the concentrate is supplied in a pellet form.
Color concentrates containing metal particles are known in the prior art. Such concentrates are utilized to impart a metallic look or effect to polymers. However, to date, the use of such concentrates has presented a variety of problems including poor incorporation or distribution of the metal within the polymer, low metal loading levels that fail to produce a meaningful metallic effect in the polymer being colored and the formation of knit lines, flow lines, diration lines and other molding marks upon use of the colored polymer. Moreover, such concentrates have commonly been made using a wax carrier, and waxes at higher concentrations are undesirable in many applications. The present invention affords a metal filled color concentrate that overcomes these deficiencies.
SUMMARY OF INVENTION
The present invention provides a new and improved metal containing color concentrate that affords a variety of advantages including a high metal content, good metal and pigment dispersibility and distribution, minimal adverse influence on the physical properties of the polymer being colored and good molding characteristics.
The color concentrate of the present invention comprises from about 5% to about 20% by weight metal particles component, from about 1% to about 15% by weight colorant material (pigment), and from about 60% to about 90% by weight thermoplastic polymer. The metal particles component comprises particles that exhibit an undefined configuration and an average particle size of from about 75 to about 150 &mgr;m. The color concentrates of the present invention include less than about 5% by weight wax.
These and other aspects of the present invention will become clear to those skilled in the art upon the reading and understanding of the specification and the claims below.
DETAILED DESCRIPTION
Color concentrates made in accordance with the present invention yield various advantages. These advantages include: (i) the production of a concentrate that provides good dispersion and distribution when added to the thermoplastic polymer being colored; (ii) the production of colored thermoplastic polymer that displays a significant metallic look or effect that is noticeable in even low light conditions (e.g., in an office or within a house); and (iii) the absence of knit lines, flow lines and diration lines upon molding of the colored thermoplastic polymer. The formation of knit lines is avoided because the metal particles do not pile up into a vertical orientation during molding. Additionally, knit lines are avoided because there is no agglomeration of metal particles within the thermoplastic polymer.
Color concentrates made in accordance with the present invention may utilize a variety of different thermoplastic carrier polymers or mixtures of such polymers. Waxes are not used as the carrier in concentrates of the present invention. Thus, the color concentrates of the present invention comprise less than 5% by weight wax. The thermoplastic carrier polymer may comprise an amorphous or crystalline material selected from the group consisting of a styrenic polymer, a vinyl halide polymer, polyamides and an olefinic polymer. The styrenic polymers include, for example, polystyrene, high impact polystyrene (HIPS), styrene/acrylonitrile copolymers (SAN), copolymers of acrylonitrile/butadiene/styrene (ABS) and substituted styrenes such as ∝-methyl styrene, methyl methacrylate, polysulphones and copolysulphones, polyphenylene oxides (PPO), polycarbonates, polymers and copolymers of acetals, and thermoplastic polyurethanes. Polyamide polymers include, for example, Nylon 6, Nylon 6,6 and Nylon 6,12. Vinyl halide polymers include, for example, poly(vinyl chloride) (PVC).
The olefinic polymers include, for example, polymers and copolymers of ∝-olefins such as polyethylene, polypropylene, polybutene, poly-4-methyl pentene- 1, propylene/ethylene copolymers and copolymers of 4-methyl pentene-1 with linear ∝-olefins containing 4 to 18 carbon atoms.
Preferably, whatever polymer system is utilized, it is best if a significant portion of the polymer is supplied in powder form to ensure proper mixing. Use of a blend of powder and pellets helps to prevent the settling of the metal particles during mixing. Preferably, the powder accounts for from about 30% to about 70% by weight of the thermoplastic carrier.
The metal particles component of the present invention comprises a distribution of aluminum particles in the range of 75 to about 150 &mgr;m having an undefined configuration. The undefined configuration and the particle size distribution have been found to be critical relative to the formation of a product with a significant metal effect. Undefined configuration means aluminum particles that display neither a spherical nor a lenticular configuration. The undefined particles have a very irregular shape. Metal particles suitable for use in the present invention may be purchased from the A Obron Atlantic Corporation of Painesville, Ohio.
The colorant material may comprise any one or more of a number of commercially available colors or pigments so as to provide the described color effect in the concentrate and the thermoplastic polymer that is to be colored. As used in this specification and claims below “colorant material” means any conventional inorganic or organic pigment or organic dyestuff. Such materials are described, for example, in
Kirk-Othmer Encyclopedia of Chemical Technology
, Third Edition, Vol. 6, pp. 597-617, which is incorporated herein by reference. Examples of inorganic pigments include, for example, titanium dioxide, iron oxide, zinc chromate, cadmium sulfides, chromium oxides and sodium aluminum silicate complexes. Examples of organic type pigments include azo and diazo pigments, carbon black, phthalocyanines, quinacridone pigments, perylene pigments, isoindolinone, anthraquinones, thioindigo and solvent dyes.
Various types of additives may also be included in the process. Such additives may include, for example, stabilizers and/or process aids such as alkaline earth metal soaps and carboxylates such as calcium benzoate, calcium octoate and calcium naphthenate, Friedel-Crafts cation progenitor compounds such as zinc oxide, zinc hydroxide, zinc carbonate, zinc acetate, zinc laurate, zinc naphthenate, zinc stearate, zinc oleate, zinc 2-ethyl-hexoate, cadmium oxide, cadmium hydroxide, cadmium carbonate, cadmium acetate, cadmium laurate, cadmium naphtheneate, cadmium stearate, cadmium oleate, cadmium 2-ethyl-hexoate, calcium stearate, aluminum oxide, aluminum hydroxide, aluminum carbonate, aluminum acetate, aluminum chlorolaurate, antimony oxide, antimony hydroxide, antimony carbonate, antimony naphthenate, tin oxide, tin hydroxide, tin carbonate, tin naphthenate, and tin 2-ethyl-hexoate, aliphatic polyhydric compounds such as trimethylolethane, trimethylolprop
Cain Edward J.
Ferro Corporation
Rankin, Hill Porter & Clark LLP
Wyrozebki-Lee Kat.
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