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
2001-02-27
2003-02-04
Sanders, Kriellion (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...
C524S434000, C524S437000, C524S449000
Reexamination Certificate
active
06515060
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to solid surface sheet material having improved physical and aesthetic properties. More particularly, the invention relates to providing solid surface sheet material comprised of highly filled acrylic resin containing a controlled amount of a selected synthetic mica.
U.S. Pat. No. 4,480,060 discloses composite pressed boards containing at least 50% mica mixed with an organic resin such as epoxy, polyimide, melamine or phenolic resin. The boards are useful in electrical applications and have an opaque, lusterless appearance.
International Publication WO98/38244, published Sep. 3, 1998 discloses products said to contain oriented pearlescent flakes of mica.
The inclusion of natural occurring mica with resins and fillers in preparing composite materials is disclosed in general terms in a number of publications.
SUMMARY OF THE INVENTION
The subject invention provides a solid surface sheet material having excellent physical properties and a lustrous, sparkling appearance which comprises an acrylic resin, from about 20 to about 75% by weight of a filler, based on the total weight of the material, and from about 0.1 to about 5% by weight of a selected synthetic mica based on total weight of the material.
DETAILED DESCRIPTION OF THE INVENTION
The resins useful in the present invention are not specially limited as long as they can be formed into a solid surface material by curing. Examples of useful acrylic resins include various kinds of conventional acrylic group monomers, acrylic group partial polymers, vinyl monomers for copolymerization other than acrylic group monomers, or oligomers. As the arylic group monomer, (meth)acrylic ester is preferable.
A particularly good and especially preferred polymer which meets all of the above properties is poly(methyl methacrylate). In a castable composition, it is often introduced as a sirup of polymer in methyl methacrylate monomer. Methods of preparing such a sirup are described in the prior art. Another method of preparing a sirup is to simply dissolve polymer in the monomer. This latter method is quite useful for adjusting viscosity of the castable composition since molecular weight of polymer as well as concentration can be varied in such a way as to control the rheology.
The amount of fluid polymerizable constituent required in the castable composition is at least 30% by volume. Methyl methacrylate monomer is preferred as a major constituent.
Other monomers useful as fluid polymerizable constituents are alkyl acrylates and methacrylates in which the alkyl groups can be from 1-18 carbon atoms, but preferably 1-4 carbon atoms. Suitable acrylic monomers are methyl acrylate; ethyl acrylate and methacrylate; n-propyl and i-propyl acrylates and methacrylates; n-butyl, 2-butyl, i-butyl and t-butyl acrylates and methacrylates; 2-ethylhexyl acrylate and methacrylate; cyclohexyl acrylate and methacrylate; omega-hydroxyalkyl acrylates and methacrylates; N,N-dialkylaminoalkyl acrylates and methacrylates; N-[t-butyl]aminoethyl acrylate and methacrylate.
Other unsaturated monomers include such compounds as bis-[beta-chloroethyl]vinylphosphonate; styrene; vinyl acetate; acrylonitrile; methacrylonitrile; acrylic and methacrylic acids; 2-vinyl- and 4-vinylpyridines; maleic acid, maleic anhydride and esters of maleic acid; acryl amide and methacrylamide; itaconic acid, itaconic anhydride and esters of itaconic acid and multifunctional monomers for crosslinking purposes such as unsaturated polyesters; alkylene diacrylates and dimethacrylates; allyl acrylate and methacrylate; N-hydroxymethylacrylamide and N-hydroxymethylmethacrylamide; N,N′-methylene diacrylamide and dimethacrylamide; glycidyl acrylate and methacrylate; diallyl phthalate; divinylbenzene; divinyltoluene; trimethylolpropane triacrylate and trimethacrylate; pentaerythritol tetraacrylate and tetramethacrylate; triallyl citrate and triallyl cyanurate.
The synthetic mica useful in providing the products of this invention are fluoro-phlogopites such as KMg
3
(AlSi
3
O
10
)F
2
. They are described in detail and a process for their preparation is disclosed in U.S. Pat. No. 5,094,852 which is incorporated herein by reference. Other useful forms of synthetic include fluoro-tetrasilicicmica (KMg
2.5
Si
4
O
10
)F
2
, sodium-fluoro-tetrasilicicmica (NaMg
2.5
Li(Si
4
O
10
)F
2
, sodium-taeniolite (NaMg
2
2Li(Si
4
O
10
)F
2
, and fluoro-hectorite Na
1/3
Mg
8/3
Li
1/3
(Si
4
O
10
)F
2
.
Fillers useful in the present invention include, for example, aluminum trihydrate, calcium carbonate, barium sulfate, Bayer hydrate, magnesium hydroxide, talc, wolastonite, as a list that is not exhaustive and not intended to limit the invention. Fillers can be present in effective amounts from as low as about 20% by weight to about 75% by weight. Preferably, amounts from 30 to 67% by weight are used.
It is known to include in solid surface materials other additives such as pigments, dyes, flame retardant agents, parting agents, fluidizing agents, viscosity control agents, curing agents (chemical and thermal), antioxidants, toughening agents and the like as known to those of ordinary skill in the art.
Solid surface materials of this invention can be prepared by cell cast, continuous casting or by reactive extrusion using a multi-feeder twin-screw extruder equipped with vacuum and a sheet die of proper dimensions. The sheets produced can be transferred either onto a double belt press or into an oven for curing. The preferred method is continuous casting. The production of filled poly(methyl methacrylate) compositions is well known in the art, see for instance U.S. Pat. Nos. 3,847,865; 4,413,089; and 4,406,662, which are hereby incorporated by reference. Light pressure may be needed for maintaining sheet gauge or profile during curing. The resulting solid surface material is thermoformable.
The invention can be further understood by reference to the following examples in which parts and percentages are by weight unless otherwise indicated.
REFERENCES:
patent: 3570056 (1971-03-01), Hall et al.
patent: 3600490 (1971-08-01), Billingsley et al.
patent: 3847865 (1974-11-01), Duggins et al.
patent: 4406662 (1983-09-01), Beram et al.
patent: 4413089 (1983-11-01), Gavin et al.
patent: 4480060 (1984-10-01), Hoda et al.
patent: 5094852 (1992-03-01), Ohno et al.
patent: 5741355 (1998-04-01), Yamamoto et al.
patent: 5947804 (1999-09-01), Fukinuki et al.
patent: WO 98/38244 (1998-09-01), None
McCumber Laura A.
Miller, III Richard C.
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