US3371135A - Method of making reconstituted marble - Google Patents

Description

1968 w. D. GOODWIN ,37

METHOD OF MAKING RECONSTITUTED MARBLE Filed D80. 7, 1964 Stone pigwent B-STAGE Caialyat I Stone Vibrator B d t Shine 111 mg Agen Pigment M Oven Recotnshtutad Catalyst ASTAGE 5 one INVENTGR.

William D. Goodwih BY J YW AT TORNE YS United States Patent Office 3,371,135 METHOD MAKING RECGNSTETUIED h iARELE William D. Goodwin, 445 Bishop St. NW., Atlanta, Ga. 30313 Filed Dec. 7, 1964, et. No. 416,43ll 6 Claims. (Cl. N h-63) ABSTRAQT 0F THE DESCLUSURE A method of making an article or body of reconstituted marble, wherein sotnes of selected size are combined with a resin matrix, vibrating the mixture to stratify the stones, curing the resin, heating the material, and cooling.

Cross reference to related applications The present invention is an improvement over the invention disclosed in the co-pending application of William D. Goodwin, Serial No. 377,631, filed June 24, 1964, for Reconstituted Marble and Method of Making Same, and includes many of the features and advantages disclosed therein.

Background of the invention Though previous methods of making reconstituted marble and other reconstituted stones have provided a product that has many uses and is quite acceptable for many purposes, it has been found that certain qualities are somewhat less than are desired. Some of the primary problems with reconstituted marble have been solved in the method disclosed in the above identified co-pending application; however, there is still the problem that the properties of reconstituted stones are due in large part to the binding agent that is used to put together the small particles of stone or other granular material.

At present, some of the more desirable binding agents available are the various synthetic resins. Resins have the desirable qualities of resistance to a relatively high degree of temperature, resistance to various acids, alkalis and other chemicals, and ease of handling to make the re constituted stone. However, the wearing quality and heat resisting qualities hardly rival the properties of genuine stone; also, the granular stone, when adhered with a resin, provides a surface sheen or glossiness without providing the visual sensation of'depth of the material. In natural stone, light passes into the stone and is reflected from the innerfaces of crystals as well as from the surface of the stone, thus providing a sensation of depth along with a surface glossiness.

Previous reconstituted stones have not caused a visual sensation of depth because they have been made up of very fine particulate stone held together by some binding agent; and, the small particles reflect substantially all of the light that strikes the surface, either at the surface of the material or at a very short distance below the surface, any distance below the surface being very slight. Further, since substantially all of the light is reflected, the material has a white appearance regardless of the color of stone comprising the material.

Summary of the invention The present invention overcomes the above mentioned objections by providing a method of preparing a material which includes relatively large particles of stone at the surface, with only the interstices filled with the very small particles of stone. With this structure, it will be seen that light can penetrate into the particles of stone and be reflected from within the particles of stone so that a person is literally looking into the material. Further, the light that penetrates into the material will be partially absorbed (more so than that which is reflected from the outer surface) to make the interior of the material appear somewhat darker; and, it is well known that, when the eye perceives a darker area, the darker area is interpreted as being farther away than the lighter areas; hence, the material will provide a visual sensation of depth.

Since the surface fabricated by the material of the present invention has relatively large particles of stone, the interstices between the large particles can be filled with very small particles to provide a surface that is predominately stone rather than binding agent, which will give to the reconstituted stone many qualities of stone rather than qualities of the binding agent.

These and other features and advantages of the present invention will become apparent from consideration of the following specification when taken in conjunction with the accompanying drawing.

Brief description of the drawing FIG. 1 is a schematic presentation of a process to make reconstituted stone according to the present invention; and,

FIG. 2 is a schematic presentation of an alternate process.

Description of the embodiments It will be understood that many basic techniques can be used in conjunction with the present invention to provide a reconstituted stone; however, it is preferable to use a process such as the one disclosed in the above identified co-pending application.

Referring to FIG. 1, it will be seen that the stone and binding agent, as well as a catalyst, and perhaps a pigmenting material, are mixed together, and the binding agent is allowed to reach its B-stage of curing. The entire mass of material is then placed into a mixer, and a pigment is added to produce the desired streaks or the like; then, the material is placed into a mold.

It will be understood that the process thus far is the same as that disclosed in the above mentioned co-pending application; however, the original mixture is somewhat different because stone including larger particles is used, whereas stone having a very small particle size is normally used for such processes. The reconstituted stone of the present invention includes particles that will just pass through a number 6 screen, in U.S. screens, although it also includes smaller particles which would be retained on a number 200 screen. This will be discussed in more detail hereinafter.

This crushed stone including the larger particles of the stone is mixed with the binding agent, catalyst, and perhaps pigment, and placed into a mold. While the mass is in the mold, the while the binding agent is still in the B-stage, the mold is vibrated. The purpose of the vibration is to cause the larger particles of stone to move toward the bottom of the mold. The length of time that the mold is vibrated can be varied widely depending partially on the density desired in the bottom surface of the material; however, it has been found that the mold needs to be vibrated at least twenty (20) seconds in order to give any noticeable result; and, vibration for a time of sixty to ninety seconds has been found to give desirable results. It will of course be understood that the mold can be vibrated throughout the time that the material is in the mold if desired.

During the vibrating of the mold, the larger particles of the stone move toward the bottom of the mold displacing the smaller particles, so that the bottom surface of the material in the mold becomes quite dense due to the preponderance of larger particles with their interstices filled with the smaller particles. It will of course be understood that the surface of the material that is against the bottom of the mold is the surface to be used, i.e., the finished side of the material.

In order to provide the high density of the material, and have some relatively large particles of stone, three basic sizes of particles are used. The largest size particle is such that one percent (1%) of the stone will be retained on a number 6 screen, and fifteen percent of the stone will be retained on a number 14 screen; the medium size particles are of such size that substantially all of the stone will pass through a number 16 screen and substantially all of the stone will be retained on a number 60 screen; and, the smallest particles are of such size that substantially all of the stone will pass through a number 4-0 screen and substantially all the stone will be retained on a number 200 screen. These three sizes of particles of stone have been mixed to provide twenty-five percent of the largest particles, twenty-five percent (25%) of the medium size particles, and forty percent of the smallest particles, the remaining ten percent (10%) being the binding agent and pigments; and, all percentages are percentages of the total weight. This mixture gives a very good quality of reconstituted marble, but the exact percentages are not intended to be slavishly followed. The percentages can be varied by plus or minus three percent (i3%) without appreciably affecting the quality of the finished product.

With the above mixture, it will be now seen that, when the stone is mixed with the resin or other binding agent, placed into a mold, and the mold vibrated, the largest particles will move toward the bottom of the mold; however, the bottom surface of the mass will not be composed entirely of the largest particles; rather, the largest particles will simply displace enough of the smaller particles for them to take their own position. This will yield a surface having a high percentage of the largest particles with the medium size and smallest particles being used to fill the interstices between the largest particles.

While one of the primary purposes of the arrangement of particles is to provide relatively large particles at the surface of the finished material in order to give the material the characteristics of stone, another advantage of the internal structure of the material is that the largest particles are sufficiently large to be well set into the material so that they are less likely to come out when subjected to abrasion or vibration; further, the smaller particles will completely surround the largest particles to give greater mechanical support for the largest particles. It will thus be seen that the entire structure is very well bonded together to provide a very durable material.

An alternative method of making reconstituted stone is shown in FIG. 2 of the drawings. The principal difference in the procedure of the method shown in FIG. 2 is the placing of the resin into the mold while the resin is in its A-stage, and adding the stone to the resin in the mold.

In more detail, the resin or other binding agent is mixed with a pigment and, while the resin is in its A-stage, placed into a mold. The crushed stone is poured into the resin and spread evenly throughout the mold. Though it may be desirable to vibrate the mold to move the large particles toward the bottom of the mold as described above, it is contemplated that sufiicient large particles will be used to make a homogeneous material, the large particles being uniformly distributed in the material.

The principal advantages of this alternate method are that there is no one finished surface; rather, any surface can be polished, and even a cut edge can be polished to have an attractive appearance. Also, with this method, there is less danger of having air bubbles. Since the resin is in its A-stage, and has a very low viscosity at the time the stone is added, any air bubbles will readily rise to the surface and the air will escape.

It will thus be seen that this method of making reconstituted stone is very simple and will provide a stone of homogeneous characteristics.

It will be realized that naturally formed marble sometimes has pieces of mica therein which give an extra shininess to the marble, and sometimes provide a spot of almost mirror-like brilliance. This feature can be duplicated in the present reconstituted marble by adding about three to five percent (3 to 5%) by volume of mica to the material, for example, to the crushed stone. This percentage can of course be varied widely depending upon the appearance desired.

When the binding agent is completely cured, or cured to the extent that the material has sufficient rigidity to support its own weight, the material is removed from the mold and placed into an oven or the like to be heated. The purpose of the heating is to drive off a substantial portion of the binding agent that is on the surface of the material, and this is discussed in more detail in the above identified co-pending application. After the binding agent has been driven off, the material can be removed from the oven and polished to be ready for use. It will be understood that the side of the material that was at the bottom of the mold is the finished side of the material, and is the only side that requires polishing; but, in the second embodiment discussed, all sides may be regarded as finished sides, and may be polished.

It will be now seen that the present invention provides a reconstituted stone that is very similar to naturally formed stone, both as to visual characteristics and physical characteristics. The large percentage of stone in the finished surface of the material provides a denseness, resistance to heat, and resistance to wear or abrasion rivaling naturally formed marble; and, the larger particles provide a visual sensation of depth as discussed above. The material can be made quite inexpensively, and the characteristics can be changed somewhat to suit any particular application.

It will be understood by those skilled in the art that the particular embodiment of the invention herein presented is by way of illustration only, and is meant to be in no way restrictive; therefore, numerous changes and modifications may 'be made, and the full use of equivalents resorted to, without departing from the spirit or scope of the invention as defined by the appended claims.

What is claimed as invention is:

1. A process of making a reconstituted stone including the steps of:

( 1) preparing a mixture comprising:

(a) stone, constituting approximately 25 percent large stone particles of 6 to 14 screen size, approximately 25 percent medium stone particles of 16-60 screen size, approximately 40 percent small stone particles of 40-200 screen size;

(b) a binding agent, and

(c) a catalyst;

(2) placing the mixture in a mixer and mixing the mixture;

(3) placing the mixture in a mold and vibrating the mold to cause the larger particles of stone to migrate toward the bottom of the mold;

(4) curing the binding agent to render the mixture a self sustaining material;

(5) removing the self sustaining material from the mold:

(6) placing the self sustaining material in an oven and heating the material to drive off the binding agent from the surface of the material; and

(7) removing the material from the oven, and cooling the material.

2. The invention of claim 1 wherein the step of remov ing the material from the oven and cooling the material is followed by the step of polishing the exterior surface of the material to the desired finish.

5 6 3. The invention of claim 1 wherein the step of prematerial to drive ofi" the binding agent from the sur paring a mixture includes adding a pigment to the mixface of the material; and ture. (6) removing the material from the oven and cooling 4. The invention of claim 1 wherein the step of placthe material. ing the mixture in a mixer and mixing the mixture in- 5 6. The invention of claim 5 wherein the step of addeludes addin a pigment to th mi t e, ing stone to the mixture comprises adding marble stone 5. A process of making a reconstituted stone including to the mixture, and further includes adding 3 t Patent th steps f; mica to the mixture.

(1) Preparing a mixture comprising:

(a) a binding agent; References Cited ('b) a catalyst, and UNITED STATES PATENTS c e 2,951,001 8/1960 Rubenstein 161-91 X (2) placing the mixture in a mold and adding stone 23 4 1/1966 Iva-Son et a1 X constituting approximately percent large stone 1,841,215 1/1932 Schneider 264 44 particles of 6 to 14 screen size, approximately 25 1 3,247,294 3/1966 Sabouni 264 44 percent medium stone particles of 16-60 screen size, 2,517,100 8/1950 Erdle X approximately percent small stone particles of 3,012,287 12/1961 Tucker 264 139 40-200 screen size, and dispersing the stone through- (3) curing the binding agent to render the mixture a 20 147,506 10/ 1962 Poland.

self sustaining material;

(4) removing the material from the mold; ROBERT WHITE Primary Examiner (5) placing the material in an oven and heating the R. B. MOFFITT, Assistant Examiner.

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