US2747229A

US2747229A - Method and composition for making lined dipped goods from latex

Info

Publication number: US2747229A
Application number: US307627A
Authority: US
Inventors: Merwyn C Teague
Original assignee: United States Rubber Co
Current assignee: Uniroyal Inc
Priority date: 1952-09-03
Filing date: 1952-09-03
Publication date: 1956-05-29
Anticipated expiration: 1973-05-29

Description

R. m m 7, Wm A 2 w W m f B M. C. TEAGUE METHOD AND COMPOSITION FOR MAKING LINED DIPPED GOODS FROM LATEX Filed Sept. 3, 1952 May 29, 1956 liningfor the glove'adhering thereto;

United States Patent METHOD AND COMPOSITION FOR MAKING LINED DIPPED GQODS FROM LATEX Merwyn C. Teague, Sparta, N. J., assignor to United States Rubber Company, New York, N. Y., a corporation of New Jersey Application September 3, 1952, Serial No. 307,627

8 Claims. (Cl. 18-585) This invention relates to a new method of making fabric-lined dipped goods from rubber latex, as well as to a new composition for coating a dipping form on which the latex is deposited.

In preparing fabric-lined dipped goods from latex, such as. rubber gloves, it is customary to prepare the desired fabric lining by sewing the requisite number of parts together, just as if one were making a fabric glove. This fabric lining is then slipped over the usual form, and the form is dipped into a rubber latex preparation, and removed with a coating of latex adhering to the 'fabric covered form. The latex is then coagulated in place, and the clipping and coagulation are repeated as fabric lining is frequently not necessary in dipped articles.

Thus, in a glove, the lining is used primarily to facilitate donning and doffing, and to absorb perspiration so that the wearer will not experience the clammy feeling that The fabric also serves to strengthen the rubber. These advantages could be obtained by using a lining that is only For example, 7

partial, with consequent saving of fabric. a lining'for a glove might be cut out of two pieces,

one that will cover the palm and the inside of the fingers,

and the other to cover the back of the hand and fingers. In such a construction, only the sides of the fingers would remain uncovered. However, the prior art has not .aflforded any'convenientand economical method of making such partially-lined dipped goods.

. The'principal' object of the present invention is therefore to provide a more satisfactory method of associating a fabric lining with a dip'pedrubber article.

Another object is the provision of a composition that can be applied to 'adipping form'to maintain a full or partial fabric lining adhesively in place on the form while a coating of latex is deposited thereover, but which will at the same time strip'free of the form without appreciable residual tack,- after the dipped article is vulcanized;

a "The manner in which the invention accomplishes the foregoing objects, aswell as additional objects and advantages; will be'made manifest in the following detailed descriptiom-which is intended to be read with reference to the accompanying drawings,wherein:

Fig. 1 shows a dipping form for making a rubber glove,

.the form being provided with a'pre-coating of the adhesive and' stripping composition of the invention;

Fig. -2 shows the pre-coated'form with a partial fabric Fig; 3 shows the form after clipping in rubber latex;

2,747,229 Patented May 29, 1956 ICC According to the invention, the form for the dipped article is first coated with a special adhesive composition comprising a resinous styrene-isobutylene copolymer, polybutene, and a silicone fluid. The resinous styreneisobutylene copolymer itself forms a non-tacky film, but the polybutene serves to make the film tacky, while the silicone serves as a parting agent. The ingredients of this pre-coating composition are conveniently applied to the form as a solution in a mutual volatile organic solvent, such solution being applied in any convenient manner, as by painting, spraying or dipping, followed by drying to remove the solvent. It has been surprisingly found that such a pre-coating composition gives a smooth, continuous, and tacky surface on the form, and a textile material, which is to form the lining, especially a partial lining, of the clipped article, may be pressed onto the thus-coated form, to which it will remain adhesively secured throughout the subsequent dipping, drying and vulcanizing operations. However, it is most unexpectedly found that after the dipped article has been vulcanized by heat on the form, the initially adhesive coating loses its tack, and the vulcanized fabric-lined article can be readily stripped from the form with a perfectly smooth and clean finish that is essentially free from stickiness, both on the fabric surfaces, and on the rubber surfaces that were in contact with the form. During the vulcanization the initially adhesive pre-coating transfers from the form to the rubber surface, leaving the form with a non-tacky, clean surface where it has in contact with the rubber. The polybutene, which was responsible for the tack of the coating, actually goes into the rubber. The areas of the form beneath the fabric, however, are left with a slightly tacky surface, but the fabric nevertheless strips free without stickiness.

The fabric is preferably treated in such a manner, before it is adhered to the form, that the rubber latex will not penetrate through the fabric during the dipping operation. Most advantageously, this is done by previously skim-coating the fabric with a thin layer or veneer of gum rubber on the side of the fabric that faces away from the form. This may also be accomplished by treating the fabric with a water-repellent material, such as 2 to 3% solution of stearic acid in alcohol, which, upon drying, renders the fabric substantially impermeable to latex. For this purpose the fabric may initially be impregnated with such a water-repellent. The preliminary skim-coating of rubber on one side of the fabric is particularly desirable because it provides for good adhesion between the fabric and the deposited latex.

The resins suitable for use in the pre-coating composition of the invention are the copolymers of styrene and isobutylene, such as are shown in detail in U. S. Patent 2,274,749 to Smyers. These copolymers are film-forming and are normally hard, inelastic, thermoplastic materials, and typically contain from about 40 to 60% by weight of combined styrene and correspondingly from 60 to 40% of combined isobutylene. The polybutene employed in the pre-coating composition is a known commercially available material. This material is thick, like honey, and the commercial grades having a melting point of from about 30 to 130 C. are most suitable. Usually from about 20 to parts of the polybutene is employed in parts of the mixture of polybutene and styreneisobutylene resin. 7

The silicone component of the coating may be any nonresinous, non-volatile, polymeric fluid silicone having a consistency, when by itself, ranging from an oily liquid to a grease. There is usually employed a commercial polymeric dimethyl silicone fluid having the formula CH3[(CH3)2SlO]zSi(CH3)3 where x is from 2 to 11. Such silicone fluids are generally mixtures of a predominating amount of one polymer of dimethylsiloxane with minor amounts of other polymers of dimethylsiloxanes within the range of the above formula. The viscosities of the methyl silicone oils typically range between 0.5 and 1,000 centistokes at 25 C., and the specific gravities typically range from 0.760 to 0.975 at 25 C. Other fluid polymeric silicones than the methyl silicones which may be used in the present invention are the ethyl silicone fluids or polymeric diethylsiloxanes, and the alkyl-aryl silicone fluids, e. g., polymeric methyl phenol siloxanes and polymeric ethyl phenyl siloxanes. The silicone should be soluble in and compatible with the polybutene and the styrene-isobutylene components of the pre-coating. For a further description of silicone fluids reference is made to Chemistry of Silicones by E. G. Rochow, published byJohn Wiley, N. Y., 2d edition, 1951, particularly chapter 6 entitled Properties of the Specific Silicone Polymers and to two articles by D. C. R. Miller in Canadian Chemistry and Process Industries, vol. 33, pages 764-767, 858-866 and 870.

A suitable polymeric ethyl silicone fluid for use in the present invention can be made in accordance with U. S. Patents 2,258,218 to E. G. Rochow; 2,377,689 to Hyde; 2,384,384 to McGregor et al.; 2,469,888 to Patnode; and 2,491,843 to Wilcock.

The silicones which are suitable for use in this invention may vary from light oil-like liquids to heavy jellies or greases. Examples are products which are sold by the Dow-Corning Corporation under the designation of Dow-Corning Stop Cock Grease, Dow-Corning Plug Cock Grease, Dow-Corning Type 200 Fluid, Dow- Corning Type 500 Fluid, Dow-Corning Ignition Sealing Grease, and Dow-Corning Anti-Foam A.

The silicones employed usually contain from 1.98 to less than 3.0 hydrocarbon radicals per silicone atom, and the hydrocarbon radicals are attached to the silicone atoms by carbon-silicon linkages. The hydrocarbon radicals may be alkyl, aryl, aralkyl or alkaryl radicals, preference being given to the lower alkyl radicals, especially methyl. Usually from about to 50 parts of the silicone is employed in 100 parts of the mixture of polybutene and styrene-isobutylene copolymer. I prefer however to employ from about 10 to 25 parts of the silicone per 100 parts of combined styrene-isobutylene copolymer and polybutene.

In preparing the form pre-coating composition any suitable volatile organic solvent capable of dissolving the styrene-isobutylene resin, the polybutene and the silicone can be used. The solvent can comprise a single material or a mixture of materials. Paratfinic hydrocarbon solvents, such as gasoline, are suitable, as well as aromatic hydrocarbon solvents, such as benzene, toluene and xylene. Other solvents such as carbon tetrachloride are also usefill. The proportion of total solids in the coating composition can vary within wide limits, depending mainly upon the method of coating. I generally make the coating composition quite thin, with a non-volatile material content of less than However, compositions having a nonvolatile content of from 3 to are also useful under proper conditions.

Application of a single coating of the mixture in any conventional manner, as by spraying or dipping, will generally give a film of sufiicient thickness to accomplish the objectives of the invention.

The following example will serve to illustrate the invention in more detail.

Example The following pre-coating composition was made up:

Parts by weight The polybutene employed was a commercial grade known as Oronite 32. The dimethyl silicone was commercial material sold under the trade designation DC-ZOO.

The form, such as the glove form 1 shown in the accompanying drawing, is dipped into this solution and dried for two minutes at room temperature. Evaporation of the solvent leaves a smooth, continuous, very tacky film 2 on the surface of the form 1. There is then provided a fabric part 3, previously cut to the desired shape of a partial lining for the glove. The fabric is previously skimcoated on its outer surface with a thin layer 4 of gum rubber to prevent the latex from penetrating the fabric, and to improve the adhesion of the latex to the fabric. The rubber layer 4 may be of contrasting color, that is, it may be of a different color than the latex, or it may have any desired design or ornamentation impressed thereon, especially if substantially transparent latex is used. A similar fabric piece is provided at each side of the form, and the bare or inner surface of the fabric is pressed firmly against the form. Care is taken to apply firm pressure to the edges of the fabric piece, which are the most likely portions to pop up. The fabric may be of any type suitable for lining, ranging from light sheeting to a heavy knitted fabric.

The form with the fabric panels in place is then dipped in the usual compounded latex bath, which may be composed of any of the usual conventional dipping solutions based either on natural rubber or one of the synthetic rubbers, followed by a dip in an acid bath, or other coagulant, to coagulate the latex in the form of an overlying film 5. This procedure is repeated if a thicker deposit of latex is desired, followed by a dip in a water bath to leach the deposit, if desired. The latex film is then cured for 40 minutes at 240 F. During the cure the polybutene and the other ingredients of the pre-coat transfers to the deposited rubber and becomes an intimate part thereof, with the result that the pre-coating composition loses its tack. It is then possible to strip the partially lined glove 6 from the form cleanly with ease. There is no tackiness either on the inner rubber surface 7 or on the inner surface 8 of the fabric. The pre-coating composition transfers with the rubber and the surface 9 of the form that was in contact with the rubber is nontacky, While the surface 10 of the form that was in contact with the fabric is somewhat tacky, but not sufliciently so to result in any difliculty in stripping the fabric cleanly. There is substantially no tendency for the coating to come off with the fabric and produce objectionable tack on the glove lining.

From the foregoing, it will be apparent that the invention provides a convenient and economical method of making fabric-lined dipped goods, especially partiallylined articles. Time-consuming and laborious preparation of the fabric parts of the lining is eliminated since they do not have to be sewed or otherwise fixed in proper relationship before they are associated with the form. By relying upon a special adhesive pre-coating composition to affix the fabric to the form, the method of the invention makes it possible, for the first time, insofar as the inventor is aware, to prepare partially lined dipped articles by a good, practical process. The use of only a partial fabric lining not only represents an economy of fabric, but also results in an article that has more stretch than a fully-lined article. The areas of rubber that are not supported with fabric provide this additional stretch.

The pre-coating composition described solves the difficult problem of holding the lining pieces securely to the form during dipping, and yet the coating also provides for easy and clean stripping of both the fabric lining and the rubber from the form after vulcanization. The precoating composition therefore possesses the essentially contradictory qualities of being a tacky adhesive when it is initially applied to the form, and an anti-adhesive stripping or parting medium after vulcanization. The fabric stays firmly in place in precisely the desired position without curling or peeling during the dipping operations, and up to the point where it becomes vulcanized. After vulcanization, however, the fabric strips free of the form and retains none of the tack of the adhesive.

It is sometimes found desirable to include in the precoating composition some milled raw rubber to supply additional tack, particularly where the fabric must be adhered to sharply curved surfaces.

It is also possible to practice the method of the invention by employing a hard, inelastic, styrene-butadiene thermoplastic copolymer resin as the film-forming ingredient in place of the styrene-isobutylene resin in the composition described above. However, the styrenebutadiene resin is less preferred, and, if it is used, it is desirable to include also about 50 or 100 parts, per 100 parts of resin, of milled raw rubber to supply additional tack.

The polybutene functions as a tack-producing agent in the composition in the initial part of the process, but, under the influence of the heat of vulcanization, it migrates to the rubber latex film, in which it is apparently preferentially soluble, particularly under the influence of the heat of vulcanization, compared to its solubility in the deposit of styrene-isobutylene resin. Thereafter the rubber surface is substantially non-tacky.

Although the polybutene is the preferred tackifying agent for use in the invention, it is also possible to use polyterpene for this purpose. Polyterpene is available commercially under the trade name of Piccolyte. However, this material is less preferred.

The silicone is a highly desirable constituent of the preferred composition used in practicing the invention, but it is not absolutely essential under all circumstances.

The method of the invention lends itself to the production of a variety of interesting effects. Thus, I have made gloves of attractive design by using a transparent latex, and a patterned fabric beneath. The fabric can be dyed in a different or contrasting color to the latex film, or it can have any desired design impressed upon it in any suitable manner. The fabric is advantageously colored by applying a colored rubber skim coat thereto.

Having thus described my invention, what I claim and desire to protect by Letters Patent is:

1. A method of making fabric-lined vulcanized rubber latex dipped articles which comprises providing a dipping form having the desired shape, coating the form with a composition comprising a film-forming thermoplastic resin selected from the group consisting of styrene-isobutylene resin and styrene-butadiene resin, and a tackifying agent, applying the desired fabric lining against the thus-coated form in adhesive relation therewith, dipping the form in rubber latex, coagulating the latex on the form, heating the thus-deposited rubber to vulcanize the same, and thereafter stripping the resulting fabric-lined rubber article from the form.

2. A method of making fabric-lined vulcanized rubber latex dipped articles which comprises providing a dipping form having the desired shape, coating the form with a composition comprising styrene-isobutylene resin and polybutene, applying a desired fabric lining against the thus-coated form in adhesive relation therewith, dipping the form in rubber latex, coagulating the latex on the form, heating the thus-deposited rubber film to vulcanize the same, and thereafter stripping the resulting fabriclined rubber article from the form.

3. A method of making fabric-lined vulcanized rubber latex dipped articles which comprises providing a dipping form having the desired shape, coating the form with a composition comprising styrenedsobutylene resin and polyterpene, applying a desired fabric lining against the thus-coated form in adhesive relation therewith, dipping the form in rubber latex, coagulating the latex on the form, heating the thus-deposited rubber film to vulcanize the same, and thereafter stripping the resulting fabriclined rubber article from the form.

4. A method of making vulcanized rubber latex dipped articles having a partial fabric lining which comprises providing a dipping form of the desired shape, coating the form with a composition comprising film-forming thermoplastic resin selected from the group consisting of styrene-isobutylene resin and styrene-butadiene resin, polybutene, and a silicone fluid, pressing individual pieces of fabric against the resulting tacky surface on the form to adhere the fabric to the form, dipping the form in rubber latex, coagulating the resulting film of latex on the form, heating the thus-formed film to vulcanize the same, whereby the said coating composition on the form in contact with the surfaces of the deposited rubber is transferred to the rubber, leaving a substantially nontacky and non-adhesive surface on the form at said surfaces, and thereafter stripping the resulting partially fabric-lined rubber article from the form.

5. A method of making vulcanized rubber latex dipped articles having a partial fabric lining which comprises providing a dipping form of the desired shape, coating the form with a composition comprising a styrene-isobutylene resin, polybutene, and a silicone fluid, pressing individual pieces of fabric against the resulting tacky surface on the form to adhere the fabric to the form, dipping the form in rubber latex, coagulating the resulting film of latex on the form, heating the thus-formed film to vulcanize the same, whereby the said coating composition on the form in contact with the surfaces of the deposited rubber is transferred to the rubber, leaving a substantially non-tacky and non-adhesive surface on the form at said surfaces, and thereafter stripping the resulting partially fabric-lined rubber article from the form.

6. A method of making vulcanized rubber latex dipped articles having a partial fabric lining which comprises providing a dipping form of the desired shape, coating the form with a composition comprising styrene-butadiene resin, polybutene, and a silicone fluid, pressing individual pieces of fabric against the resulting tacky surface on the form to adhere the fabric to the form, dipping the form in rubber latex, coagulating the resulting film of latex on the form, heating the thus-formed film to vulcanize the same, whereby the said coating composition on the form in contact with the surfaces of the deposited rubber is transferred to the rubber, leaving a substantially non-tacky and non-adhesive surface on the form at said surfaces, and thereafter stripping the resulting partially fabric-lined rubber article from the form.

7. A method of making vulcanized rubber latex dipped articles having a partial fabric lining which comprises providing a dipping form of the desired shape, coating the form with a composition comprising styrene-isobutylene resin, polybutene, and a silicone fluid, to provide a tacky surface on the form, providing individual pieces of fabric to constitute the said lining, the said fabric having a skim-coating of rubber on one surface, and being exposed on the other surface, pressing the said individual pieces of fabric against said tacky surface, with the rubbercoated surface of the fabric facing away from the form, and the exposed surface of the fabric in contact with said tacky surface, to adhere the lining to the form, dipping the form in rubber latex, coagulating the latex on the form, and heating the resulting rubber film on the form to vulcanize the same.

8. A method of making vulcanized rubber transparent latex dipped articles having a partial fabric lining of contrasting color which comprises providing a dipping form of the desired shape, coating the form with a temporarily adhesive composition comprising styrene-isobutylene resin and polybutene, to provide a tacky surface on the form, providing individual pieces of fabric to constitute the said lining, the said fabric having a skim-coating of rubber of contrasting color on one surface, and being exposed on the other surface, pressing the said individual pieces of fabric against said'tacky surface of the form, with the rubber-coated surfacetof the fabric facing away from the form, and the exposed surface of the fabric in contact with said tacky surface, to adhere the lining to the form temporarily, dipping the form in rubber latex, coagulating the resulting film of latex on the form, heating the thusdeposited film to vulcanize the same, whereby the said coating composition on the form in contact with the surfaces of the deposited rubber is transferred to the rubber, leaving a substantially non-tacky and non-adhesive surface on the form at said surfaces, and thereafter stripping the resulting partially fabric-lined rubber article from the form.

1 UNITED STATES PATENTS Miller Dec. 21, 1915 Pope ,May 16, 1933 Foley May 29,1934 Diller Feb. 4,1936 Rogerson Feb. 24,1942 Winder Sept. 28, 1943 Gammeter et a1. Mar. 20, 1945 Rumbold Jan. 14, 1947 FOREIGN PATENTS Australia Mar. 21, 1946

Claims

3. A METHOD OF MAKING FABRIC-LINED VULCANIZED RUBBER LATEX DIPPED ARTICLES WHICH COMPRISES PROVIDING A DIPPING FORM HAVING THE DESIRED SHAPE, COATING THE FORM WITH A COMPOSITION COMPRISING STYRENE-ISOBUTYLENE RESIN AND POLYTERPENE, APPLYING A DESIRED FABRIC LINING AGAINST THE THUS-COATED FORM IN ADHESIVE RELATIVE THEREWITH, DIPPING THE FORM IN RUBBER LATEX, COAGULATING THE LATEX ON THE FORM, HEATING THE THUS-DEPOSITED RUBBER FILM TO VULCANIZE THE SAME, AND THEREAFTER STRIPPING THE RESULTING FABRICLINED RUBBER ARTICLE FROM THE FORM.