USRE18363E - Morgan k - Google Patents

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Reissued Feb..23, 1932 UNITED STATES PATENT OFFICE MORGAN K. ARMSTRONG, OF WASHINGTON, DISTRICT OF COLUMBIA, ASSIGNOR, BY MESNE ASSIGNMENTS, TO UNITED STATES GYPSUM COMPANY Monomer COMPOSITION No Drawing. Original application filed April 29, 1920, Serial No. 377,421. Renewed JMarch 4, 1927. OriginalNo. 1,641,611, dated September 6, 1927; Application for reissue filed October 26, 1929. Serial This invention relates to an improved plastic mixture and relates more particularly to a molding composition suitable for the cores of plaster boards or for use in making molded forms and the like.

The object of the invention is to produce a novel and useful plastic mixture, more particularly adapted for use as a body, core or filler for plaster Wall boards, for molded forms and the like.

The plastic mixture is of the kind described in Letters Patent No. 1,331,554 granted to m e February 2 1, 1920, and includes as its main ingredient a full clay, or soil containing a comparatively large proportion of clay.

T e clay or soil is deflocculated as in my earlier patent, first mixing it with Water in a suitable receptacle and then subjecting it to the action of an electrolyte, as sodium phosphate. The electrolyte is added in an amount suflicient to precipitate the greater part of the soluble constituents of the clay, the amount varying with different clays and being determined by experiment.

After or during the process of deflocculation, a very small percentage (one-half to three-fourths of one percent) of some organic colloid such as starch or dextrine, is added and thoroughly dissolved in the mixture.

To the processed clay, I then add, in a liquid state and either cold or hot, bitumen,

asphalt, coal tar or other water-proofing material. The amount of water-proofing material addedto the processed clay should preferably approximate the volume of Water added to the clay in the process of deflocculation. The water-proofing material is thoroughly incorporated by agitation with the treated clay to form an emulsion.

The emulsion thus made may be produced in large quantities and may be placed in suitable receptacles to be kept on hand, ready for use when needed, to make the improved plastic mix.

When desired for use in a plastic mix for making plaster board, molded products, or

the like, finely ground calcined gypsum is added to the clay mix or slurry contamlng the bituminous substance, and the two are thoroughly mixed together. The plastic mix is then ready for immediate use, as for exmix is to be used. I In the case of the use of the plastic mix in making plaster board, the proportions of the clay mix and of the calcined gypsum are 40% of gypsum and 60% of the clay mix emulsion.

The combined Water of the hydrates of the clay mix, as Well as the water added in the process of deflocculation, provide the water for hydrating the gypsum when the plastic mix is being used for any of its intended purposes.

The bitumen, asphalt, coal tar or like Wat-- ter-proofing content of the plastic mix not only acts to make it Waterproof, but in addition it adds greatly to the tensile and compressive strength of the mixture when dry. Thus when the mixture is used for making board for example, the increased strength of the mixture greatly increases the resistance of the board to bending, shearing or other breaking strains.

Again, the particles of plaster possess greatly increased adherence, so thata nail driven through the plaster, as when nailing a board made of the plaster to studding, Will not break the plaster. The new plaster is thus an efficient nailing mixture. The excess of clay, over and above that necessary for emulsification of the asphalt, acts as a filling agent in the final composition, and this filling agent is firmly held together by the binding agent which is composed of bothethe asphalt and the gypsum or. other cementitious mater al. aphalt by combining with the Water and setting up as a binding agent for the filling agent and the composition as a whole.

I would state in conclusion that While the above disclosure represents a practical embodiment of my inventionfI do not wish to .limit myself precisely to these details, since The gypsum serves to de-emulsify the varied, without departing from the spirit of the invention as defined in the appended claims.

Having thus described my invention, I 5 claim as neW,-and. desire to secure by Letters Patent 1. A rigid, waterproof, nail penetrable Wallboard comprising a plastic mix of defiocculated clay, a bituminous material, and

calcined gypsum in such proportions that the product has the properties specified.

2. A rigid, nail penetrablewallboard comprising a plastic mixture of a large percentage of calcined gypsum, Water and bitumen,

said bitumen having been emulsified to render it miscible with water by an emulsifying agent such as defiocculated clay.

3. A rigid, nail penetrable wallboard comprising a plastic mixture of about 40% calcined gypsum, and about 60% of a mixture containing asphalt, water and a filling agent.

MORGAN K. ARMSTRONG.