This invention relates to simulated colored 5 granite and its production, using filler of alumina trihydrate (ATH) in syrup and pre-ground particles of ATH-filled polymer.

This is an improvement for making simulated granite articles with colors other than black and 10 white over U.S. Patents 4,085,246 (1978) and 4,159,301 (1979), both to Buser, Roedel and Vasilliou. U.S. Patent 3,7,75,,364 ^"* :(-19 3) - Duggins, describes casting -- ^~ ~ andTpolymerization systems useful in the present invention. All three of these patents are hereby 15 incorporated herein by reference.

U.S. Patent 4,544,584 - Ross (1985) describes technology for making simulated stone products including colorants. Summary of the Invention provides a preparative article comprising

A. 60 to 99% by weight (based on weight of the article) of a matrix comprising

(1) 30 to 45% by weight (based on weight 25 of the article) of methyl methacrylate polymer selected from the group consisting of methyl methacrylate homopolymers and copolymers of methyl methacrylate with alpha-beta-ethylenically unsaturated compounds, and 30 (2) 30 to 60% by weight (based on weight of the article) of alumina trihydrate particles having a maximum particle size less than about 100 microns in the longest dimension;

B. 0.8 to 20% by weight (based on weight of 35 the article) particles in the size range of 100 to

5000 (preferably less than 2000 or less than 800) microns comprising a particle matrix of methyl methacrylate polymer selected from the group consisting of methyl methacrylate homopolymers and copolymers of methyl methacrylate with alpha-beta- ethylenically unsaturated compounds, filled with (based on the weight of the particles) 50 to 70% by weight alumina trihydrate and up to 2.5% by weight pigment, having a clear to white color; c. 0.1-10% by weight (based on weight of

selected from-the group consisting of methyl methacrylate homopolymers and copolymers of methyl methacrylate with alpha-beta-ethylenically unsaturated compounds, filled with (based on the weight of the particles) 0.1-2.5% pigment having a black color;

D. 0.1-10.0% by weight (based on weight of

i i l h selected from the group consisting of methyl methacrylate homopolymers and copolymers of methyl methacrylate with alpha-beta-ethylenically unsaturated compounds, filled with (based on the weight of the particles) 0.1-2.5% pigment of selected color other than black and white; and

E. 0-1% by weight (based On the welght of the article) of pigments of selected colors in at least the matrix of A.

F. 0-5% by weight (based on the weight of the article) of rheological additive such ^' as core-shell particles of butadiene-styrene core grafted with polymethyl methacrylate to form the shell.

In some situations, the preferred particle size for B, C and D is between 2000 and 5000 microns. Detailed Description

In order to provide simulated granite articles with colors other than black and white and desirable aesthetics more economically, it has been discovered that the ATH content of the matrix should be increased above that normally used and to a particular narrow range within the general teachings of related art, while the content of ATH-filled particles should be decreased and appropriate pigments added to the particles. Optionally, the matrix can be pigmented at low levels. Since the particles can be more costly than the matrix resin, this permits cost savings.

Desirable sand-colored simulated granite can be made using brown and yellow pigmented particles, and pink to rose colored simulated granite can be made using red pigments in the particles. Similar pigments cajT _^ be used in the matrix.

range of 30 to 60%, preferably 45 to 55%. All parts, percentages and proportions are by weight, based on the weight of the article, except where indicated otherwise. Percentages of filler in pre-ground particles are by weight based on the weight of the particles themselves.'

The content of pre-ground particles in the article preferably is down from a normally used 33% to 5-20%, more preferably at least about 10%. These changes, surprisingly, permit significant improvement in aesthetics with sustained physical, chemical and mechanical properties.

The problem of particle segregation as a result of the wide range of particles size preferably is prevented by the use of a thixotrope, using rheological additives, especially for the use of larger ground up particles above 2000 microns. The thixotrope can be organic or inorganic in nature. Without the thixotrope, the large particles tend to settle to the bottom and the smaller particles tend to float on the top during the polymerization process. As a result, the appearance of the surface is undesirable and uncontrollable due to the

to eliminate the segregation by building the mix viscosity were unsuccessful. It is only when a thixotrope is used that the settling is eliminated. As a result of such additive, the appearance is greatly improved, a three-dimensional appearance is

contains PMMA-butadiene styrene shell-core particles of about preferably in the range of 0.1-2 micron particle size, such as 0.2 microns manufactured by Kaneka Texas Corporation.

In the following examples and comparative test, formulations are presented which are processed as in the above-cited Buser et al patents and others known in the art to produce useful end product in the form of flat sheet and shape such as kitchen sinks and bowls. The sieve size series used are in the American Standard Sieve Series in which 25-50 mesh is 700-300 microns and 50-100 mesh is 300 to 150 microns.

The particles are preformed methyl methacrylate polymer (PMMA) filled with about 62 to 65% by weight ATH particles and -comminuted by techniques known in the art to the indicated mesh sizes, which are all in the range of 100 to 5000 microns. The total filler level is also indicated, showing how much ATH plus pre-ground particles are in the matrix syrup. Suitable pigments known in the art including metallic particles for a glittering appearance can be used.

The comparative test gave acceptable results but in different color families, black and white rather than sand or rose. For obtaining the colors other than black and white, the present invention is particularly useful.

Exam le 1

Thixotrope -

Kane ACE-B22 (Kaneka Texas Corporation) 1.0