US 2606325 A
Description (OCR text may contain errors)
Patented Aug. 12, 1952 AGE S-TAIN-RESISTING'ARTIGLE F Y r As rIoIzEp POLYVINYL CHLORIDE z ,CarlgA. Nielson, Takoma. Park, and Fred Leonard, V V "Silver S=pring, Md., and Irving Cort, Washington, D. 0.,assignors to the United States of America as represented by the Secretary or the 2 Claims.
The invention described herein may be manufactured and used by or for the Government for governmental purposes, without payment to us of any royalty thereon.
There has been made in recent times marked progress in the production of gloves'or coverings for prosthetic hands, whichgloves simulate in high fidelity the appearance and texture of a natural hand, thereby renderinginconspicuous to an observer the deformity resulting from' an amputation and use of an artificial or prosthetic hand.
Such gloves essentially duplicating the appearance of a natural hand in color and surface marking's are being obtained by molding, or casting a vinyl chloride polymer and plasticizer therefor in a seamless, one-piece metal (nickel) mold. and heating the cast resin while'in the'mold to an elevated temperature .to f effect solution of the swelled or gelled resin in "the plasticizer and developthe maximumtensile. strength and tear resistance. Theglove then is removed from the mold and pigmented interiorly to match the .color of a natural mating hand;
'In the course of use, the glove comes into contact with many different. varieties of materials which tend to stain or to. discolor "the glove'in a permanent manner, such straining detracting from the appearance and wearing qualities of the No Drawing. Application August 1,1949, Serial No. 108,046 j 1 (om-'1)- v ".jf rantefliunaer the act of March :3, 1883, as Y 'amerl ded April 30, 1928; 370 O. G. 757) glove. It has been foundin practice that a plasticized polyvinyl chloride glove is stained irreversibly by. a wide variety of materials. This staining is due to the high solvent power of the plasticizer in the composition towards various oil-soluble dyes used in shoe polish, ball-point ink, and many other materials. T
Not only in connection with the production of gloves but in connection with many other applications of vinyl resins, continued advances have been made in the technology oi. vinyl resins through modifications, combinations and development of improved plasticizers, pigments and processing. Through these advances, many uses for such resins have been found and exploited, such as shower curtains, raincoats, umbrellas, furniture upholstery, and flooring material. Military, uses for the resins include gun covers; tent windows, coated fabrics, maps, and vinyl coatings on metals. The use. of the. vinyl resins in the aforesaid cosmetic gloves for amputees, both civilian and military, is a very recent use of such resins.
While many advantages may be listed in favor of plasticized polyvinyl chloride-type resins, there are several disadvantages which arise principally from the inability of the stocks to resist soilage. Incorporation of the above-indicated enhanced 2 properties in polyvinyl chloride stocks would undoubtedly result in increased application and utility. U V
In connection with the use of plasticized vinyl chloride polymers in cosmetic gloves the problem of irreversible soilage is of extreme importance. For example, gloves" in by amputees over an extended period of time tend to become somewhat dark and glossy before: thewearing life of the gloves has become exhausted; and rubbing against newsprint, clothing, or the like which is inevitable during wearing of the gloves, is found to have a' tendency to produce stains which cannot be removed readily by soap andwater or the usual solvents without producing undesirable effects.
The present invention provides a process for preventing the deleterious effects of irreversible soilage and. aging on plasticized polyvinyl chloride stocks;and whilemot-limited to cosmetic gloves, the invention is of especialapplicability thereto, as it affords full projtee on without obliterating or obscuring any offthe finesurface details or natural appearance which characterize such glgves produced'from. plasticized polyvinyl chlori e. 1 l I In accordance with; theprcsentinvention, it has been found that coatingthe plastieized polyvinyl chloride stocks with ,the" unplasticized; copolymer of ethyl acrylate iand acrylonitrile parts to 10 parts respectively)" 0t high molecular weight, an excellent adhesion of thecopolymer as acoating film to the plasticized polyvinyl chloride.
stocks can be obtained, and the resulting coated stocks remain free fromthe objectionable disadvantages that are found to be. inherent in the polymerized polyvinyl chloride. ,For depositing a flexible film of the 90-10 copolymer of ethyl acryl: ate and acrylonitrile, the flexible; film being free from plasticizing constituents for: the said poly-' mer, it is merely necessary to spraygallatex dispersion or solution-of the copolymer on the plasticized'polyvinyl chloride'sheet or shape and allow it to dry. -An' oven may bev used-to hasten the drying time; Y j
The unplasticized copolymer of ethyl acrylate and acrylonitrile may be preparedby polymerizing these materials together at from aboutl5 C. to about 20C, in asealed container using potassium persulphate as catalyst, and in the presence of a reducing agent, for example sodium hyposulphite, about 0.5 per cent by weight of resins being the catalyst and sodium hyposulphite. An aqueous dispersion of the resulting copolymer is obtained as an aqueous latex emulsion.
More specifically, the emulsion may be prepared Ingredients: Parts by weight Ethyl acrylate 90 Acrylonitrile 1t); Potassium persulphate (catalyst) 0.5
Sodium hyposulphite (reducing'agenwhp f 0.5 Santomerse D (100'partsof} l%) l 1 Water 9 9 The Santomerse D" employed in the foregoing illustrative composition is one of .the series of santomerses manufactured by the Monsanto Chemical Company. The santomerses are salts of:
a homologous series of substituted. aromatic S111: I
" if withlaticesof polyethyl acrylate and other esters of acrylic acid, such as methyl acrylate, butyl phonic acids, used as wetting, spreadingapenetrating, and emulsifying agents."
Production of the emulsion To a solution of the Santomerse D in water contained in a bottle there were added the ethyl acrylate and acryl0nitrile.- The mixture was placed on a shaking machine and agitated until the emulsion appeared homogeneous, this requiring about five minutes. The persulphate and mmsulphate were added,the"bottle sealed and placed in a polymerization bath and rotatedend over end at C. Approximately eight hours is suflicient to obtain complete polymerization. The emulsion of the polymerized monomers thus formed is applied to the plasticized polyvinyl chloride base. The emulsion may be applied by spraying, brushing, or the plasticized polyvinyl chloride base may also be dip-coated. I
It is found, surprisingly enough, that the emulsion when dried to form the-coating, in no way impairs the desired qualitiesof the'plas'ticized polyvinyl chloride sheet or base, and actually renders the base highly resistant'to irreversible soilage and aging. "For example, an uncoated sheet and a coated sheet weremarked both with a ball point pen and rubbed'with newsprint. The
specimens then were washed with soap and water or water-alcohol mixtures, and the resulting stains were easily removed from the coated sheet, whereas the unco'atedsheet resisted removal. A similar result was obtained with a coated plasticized polyvinyl chloride cosmetic glove, as an uncoated glove.
As applied, the coating is a'transparent, elastic film. tightly adherent to the base. Application of the technique of this invention to a molded cosmetic glove made of plasticized polyvinyl chloride shows that the deposition of the flexible ethyl acrylate-acrylonitrile copolymer film causes no impairment of the convincing detail-inherent in the original unsprayed glove.- i I I i The coating is, as has been pointed out above. an emulsion dispersed or solution dispersed copolymer of ethyl acrylate and acrylonitrile. As prepared, the material has a tensile strength of approximately 800900 pounds per square inch, an elongation of approximately GOO-700% and a 100% modulus of 70 pounds per square inch, and good recovery. The low modulus and high elongation compared to the plasticized polyvinyl chlo-' compared with ride glove makes it possible to flex the glove repeatedly without causing thecoating to crack and peel. H T I The adherent bond between the plasticized polyvinyl chloride base and the coating is due probably to hydrogen bonding between the plasticizer in the polyvinyl chloride resin and the rather "active tertiary hydrogen alpha to the negative cyanide 0r carbonyl group in the copolymer. The
adhesive bondis higher in magnitude than the breaking strength of the copolymer.
While the use of the -10 copolymer of ethyl acrylate and acrylonitrile is preferred as the protective coating in accordance with this invention,
the-invention is not limited to the use of such ,copolyn er, as copolymers of varying compositions .may be used, and similar results may be obtained acrylate and other higher alkyl acrylates and copolymers'thereof.
Having thus described our invention, what we claim as new and wish to secure by Letters Patent 1. As anew article of manufacture, a freely flexible base composed 'of plasticized polyvinyl chloride having bonded thereto a continuous and permanent coating film composed essentially of an unplasticized copolymer of ethyl acrylate and acrylonitrile containing approximately 90 parts by weight of ethyl acrylate and 10 parts by weight of acrylonitrile, the film having a flexibility substantially greater than that of the base and characterized by high resistance to irreversible soilage and aging. g
2. As a new article of manufacture, a cosmetic glove for covering an artificial hand and duplicating in high fidelity all surface characteristics of a natural hand the said glove being composed of a freely flexible plasticized vinyl chloride polymer base and a continuous transparent coating film'covering permanently coating the base and composed of the copolymers of ethyl acrylate and acrylonitrile containing approximately 90 parts by weight 'of ethyl acrylate and approximately 10 parts by weight of acrylonitrile, the said coating being continuously'adherent to the base and having a'flexibility substantially greater than that of the base, and characterized by high resistance to irreversible soilage and aging. thereby protecting the plasticized vinyl chloride polymer base against deterioration by aging and irreversible staining.
j CARLA. NIELSON.
' FRED LEONARD. I, IRVING CORT.
' REFERENCES CITED vThe following references .are of record in the fileof this patent: f
v UNITED STATES PATENTS Number Name Date 2,060,342 Palicki Nov. 10, 1936 2,332,461 v f Muskat et al. 1...... Oct. 19, 1943 2,453,604 Tenenbaum Nov. 9, 1948 1,473,723 I Nelson June 21, 1949 2,491,097- Feagin Dec. 13, 1949 .4 1.192 Frowde Dec. 13, 1949