US2393437A - Plastic product and method of forming same - Google Patents

Description

' following materials in Patented Jan. 22, 1946 OFFICE PLASTIC PRODUCT AND METHOD OF FORMING SAMEJ Zachary Taylor Walter, Los Angeles, Calif.

No Drawing. Application June 16, 1941,

Serial No. 398,300,

2 Claims.

great strength and durability, which are of rela-' tively light weight, which do notrequire critical atmospheric conditions for manufacture, and

which require a minimum of time for curing.

Another object is the provision of a process and product in which a woven fabric material is impregnated with a solution containing a base mafor various purposes are known, but heretofore those compounds have been of a character requiring for their curing atmospheric conditions not available in any but critically air-conditioned plants, and the length of time required for their curing has rendered them unadaptable for the purposes of my invention. Furthermore, hereto-.

fore such compounds have not been utilized or suitable for the production of articles of manufacture requiring greatstrength and durability.

- My invention overcomes those sho tcomings. For

instance, with theuse'of my invention, it is easily possible'to manufacture a boat of considerable size within a relatively few hours under ordinary. atmospheric conditions and at relatively small cost, and such a boat has great strength. My invention also may be utilized to advantage in constructing other products such as airplane wings, vehicle bodies, furniture, cabinets and the like.

In carrying out my invention, I first prepare a volatile solvent solution containing ethyl acetate, isopropyl alcohol, toluene and benzene, tc

which I add a cellulose ester or other cellulose derivative, preferably ethylcellulose. In a preferred example, I use a solvent containing the by volume:

r -Per cent Ethyl acetate 40 Isopropyl alcohol 20 Toluene 5 .Benzene 35 the following proportions,

' anol or otheralcohol having the general formula to which I add 13%, by weight, of ethylcellulose of relatively low viscosity and having 45%47% ethoxy content.

Next, I impregnate asuitable woven fabric with this solution and stretch it upon a smoothsurfaced matrix, after which I immediately apply a an additional coat of the solution and allow it to cure for about ten minutes at the end of which period the'impregnating and coating materials are cured from the wet or liquid stage to a mass which, while not fully hardened and may still re-. tain a relatively small proportion of volatiles, is not tacky. Then I superpose thereon a second lamina consisting of a like sheet of fabric impregnated and coated in like manner. Successive laminae may be added in the same manner until a product of desired thickness is obtained, each lamina being preferably pressed onto the preceding lamina by some suitable means such as a flexible spatula, to obtain a smooth product. Assuming, for instance, that the product being fabricated is a boat, the matrix would be shaped to conform to the inner surface of the boat. After the last lamina' is applied, I preferably allow the f product to remain on the matrix for a curing time of approximately 2 to 6 hours, after which it is removed from the matrix and allowed to cure finally for approximately 72 hours before being placed in use. The product thus formed is substantially monolithic, impervious to water and will not burn as readily as wood.

While I have named a preferred composition having particular advantages, I may vary the relative proportions of the ethyl acetate and the toluene and benzene to control and alter the evaporation rate, and other non-polar hydrocarbons may be substituted for the toluene and benzene. Also the proportion of isopropyl alcohol may be varied within the range of 20%-30%, and it is possible tosubstitute anhydrous ethanol, meth- CnHZn-HOH for the isopropyl alcohol. The proportion of ethylcellulose may be varied but slightly, the optimum range being 12%-14% by weight.

1 While I have said that any suitable woven fabric may be used, I find a Jute fabric, such as burlap, peculiarly well adapted for use in con- Junction with my particular compound, because the degraded cellulose products or gum which form the greater part of the jute mass are somewhat mutually soluble in the solvents I have selected for the ethylcellulose contained in my compound, so that when the solution is applied, the sum of the jute fabric and the ethylcellulose become an integral mass, greatly enhancing the of the composition, forms a part 01' my invention.

and individually curing each superposed sheet until the impregnating and coating material car- Plasticizers'may be used in my composition to confer special properties, if desired.

In the foregoing description, I have resorted to considerable detail for the purpose or making my invention understood, but I wish it understood that in its broader aspects as defined by the annexed claims, my invention is susceptible of various adaptations and modifications.

I claim:

l. The process of producing a substantially monolithic, laminated, molded plastic product which consists of impregnating sheets of porous fabric with a volatile solution containing a cellulose derivative and a solvent therefor, stretching one of said sheets over a matrix formed to shape ,9. surface of the product, and successively superposing thereon additional of said impregnated sheets until the desired number of laminae is obtained, applying a coating of said solution to ried thereby passes from the wet stage to a mass beiore superposing thereon the next successive sheet.

2; The process of producing a substantially monolithic, laminated, molded plastic product which consists of impregating sheets of woven fabric with a volatile solution containing ethyl cellulose and an aromatic non-polar hydrocarbon solvent therefor, stretching one of said sheets over a matrix iormed to shape a surface of the product, and successively superposing thereon additional 01 said impregnated sheets until the desired number of laminae is obtained, applying a coating of said solution to and individually curing each superposed sheet until the impregnating and coating material carried thereby passes irom the wet stage to a mass before superposing therego on the next successive sheet.

ZACHARYTAfilOR WAL'I'ER.