Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Processes of preparing a desired or intentional composition...
Reexamination Certificate
2000-06-12
2002-01-08
Moore, Margaret G. (Department: 1712)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Processes of preparing a desired or intentional composition...
C106S419000, C523S454000, C523S455000, C523S461000, C524S091000, C524S101000, C524S291000, C524S359000, C524S432000
Reexamination Certificate
active
06337362
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to ultraviolet (UV) resistant products such as paints, coatings, finishes, plastic articles and the like as well as to methods for the production thereof. Specially, the invention relates to compositions for use as premixes in the production of a variety of such UV resistant products particularly paints and coatings. More particularly, the present invention relates to products containing inorganic UV resistant agents in the form of micronized zinc oxide materials in combination with one or more ultraviolet-absorbing or protective organic compounds; hereinafter organic UV protective compounds and to compositions designed to serve as premixed additives for use in the manufacture of diverse products requiring protection from UV degradation wherein the premix compositions contain micronized particulate inorganic zinc oxide materials in combination with one or more organic UV protective compounds.
BACKGROUND OF THE INVENTION
A. Historical
Small particle size (i.e., micronized) non pigmentary zinc oxide have been used heretofore as UV blocking/scattering additives. For example, such micronized zinc oxide particles have been dispersed in polymer substrates for the purpose of minimizing ultraviolet radiation degradation of the substrates. The zinc oxide particles either scatter or absorb harmful ultraviolet radiation thereby reducing damage to the polymer substrate. The polymer substrates into which such particles have been dispersed include paints and other coatings and plastic articles and the like which are used outdoors and hence are exposed to solar radiation. An example of a plastic article which has included zinc oxide particles for UV weatherability is polyvinyl chloride siding used in the construction or renovation of buildings and homes.
While the ability of zinc oxide to absorb and scatter ultra-violet radiation is well known, conventional zinc oxide is typically a white, opaque powder and as such is unacceptable in appearance for use in applications (for examples clear coatings and plastics) where transparency is essential. Recently it has been discovered that reducing the particle size of zinc oxide to below the wavelength of visible light will result in visible light being transmitted through the zinc oxide thereby causing it to appear virtually transparent when in a dispersed form, e.g. a dispersion in oil or in a polymeric substrate. Moreover, such small particle size metal oxides have the added advantage of more effectively scattering and absorbing ultra-violet light.
Palmer et al. U.S. Pat. No. 5,504,134 describes attenuation of polymer substrate degradation due to ultraviolet radiation through the use of metal oxide particles (i.e., zinc oxide) in a size range of about 0.001 micrometer to about 0.20 micrometer in diameter, and more preferably from about 0.01 to about 0.15 micrometers in diameter.
Laundon U.S. Pat. No. 5,876,688, the disclosure of which is incorporated by reference, issued to assignee hereto, teaches a method for producing micronized zinc oxide particles that are small enough to be transparent when incorporated as UV blocking/scatterring agents in paints, coatings, finishes, plastic articles, cosmetics and the like which are well suited for use in the present invention.
The ability to manufacture small size transparent zinc oxide particles such as those described in U.S. Pat. No. 5,876,688 has greatly enhanced the desirability of incorporating zinc oxide as a physical sunblock agent in products such as cosmetic sunscreen compositions. For example, U.S. Pat. No. 5,587,148, discloses sunscreen formulations comprising micronized particles of pure, zinc oxide sunblock suspended in a dermatalogically suitable liquid carrier, preferably in the form of an emulsion. The patentee states that micronized zinc oxide particles measuring up to about 0.2 microns in diameter can form a visibly transparent sunscreen when applied to human skin. These particles are said to be capable of absorbing a substantial quantity, if not all, of the UV radiation to which the user is exposed.
In contradistinction with zinc oxide i.e. inorganic particulate materials discussed above, i.e., the micronized zinc oxides which act as physical agents to scatter or block UV radiation, there are numerous well-known organic compounds which protect against solar damage by virtue of chemical structures which absorb UV radiation or generate free radicals as scavengers to inhibit the harm caused by UV light. Such organic UV-protective compounds have been disclosed in the art for dermatalogical use, for example, see Siddiqui et al U.S. Pat. No. 6,015,548 and Liu et al U.S. Pat. No. 5,916,544; but also for use in non-dermatological thermoplastic polymeric compositions. Examples of organic UV absorbers are disclosed in U.S. Pat. No. 6,015,548 include ethylhexyl methoxycinnamate, padimate O, oxybenzone, octyl salicylate, TEA salicylate, octocrylene, homosalate, menthyl anthranilite and the like. Examples of UV absorbing compounds typically used in plastics fabrication are the benzophenones, the benzotriazoles,the triazines and the hindered amine light stabilizers as disclosed, for example, in Lau et al U.S. Pat. No. 6,051,637 and Samuels U.S. Pat. No. 6,051,637. U.S. Pat. No. 5,916,544 describes concentrates for sunscreens for skin in the form of dispersions which include ultrafine titanium dioxide, zinc oxide and mixtures thereof with an organic sunscreen agent and a polyvinylpyrroliidone alkylated with a C
4
-C
36
alpha-olefin dispersing aid. Zinc oxide synergist systems are known which used zinc dimethyl and diethyl dithiocarbonates with pigmentary zinc oxide in polyolefin. Commercially, CIBA sells combination products of metal oxides, hindered amines and stearates (trade name Tinuvin 492 and 494) as light stabilizers.
However, pre-mix compositions suitable for UV protection of paints, coatings, finishes, plastic articles and the like have not been known or described heretofore which employ both inorganic micronized metal oxide particles and organic UV protective compounds. Premix compositions containing micronized metal oxides such as zinc oxide and at least one organic UV protective composition which are adapted for use in formulating paints, coatings, finishes, plastic articles, and the like have not been known or disclosed previously.
B. Object of the Invention
It is an object of the present invention to provide a UV stabilized paints, coatings, finishes, and the like in which UV protection is afforded by introducing therein a mixture of a micronized UV blocking inorganic zinc oxide and at least one UV organic protective compound.
Another object of this invention is to provide UV stabilized plastic articles in which UV protection is afforded by introducing therein a mixture of a micronized UV blocking inorganic zinc oxide, and at least one organic UV protective compound.
A further most important object of this invention is to provide premix compositions containing micronized zinc oxide, and one or more organic UV protective compound in predetermined proportions adapted for admixture with substrates in the manufacture of paints, coatings, finishes, and plastic articles.
Yet another object of the invention is to provide a composition containing a predetermined amount of a micronized zinc oxide thereof and a predetermined amount of one or more organic UV protective compounds in the form of a premix composition, wherein the proportion of predetermined amounts of the ingredients of the premix are selected to satisfy the requirements for the specific end product into which the premix composition is to be incorporated.
These and other objects will become apparent hereinafter to a person skilled in the art.
SUMMARY OF THE INVENTION
In a preferred embodiment of the present invention, it has been found that one or more of the above-identified objects, and others, can be accomplished utilizing an ultraviolet protective premix composition optionally comprising a binder/substrate material and/or a polymeric resin substrate; a micronized part
Reynolds William
Van Doren Robert
Aylward D.
Cronin Michael J.
Elementis Specialties, Inc.
Moore Margaret G.
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