Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Processes of preparing a desired or intentional composition...
Patent
1997-07-08
1998-12-29
Niland, Patrick D.
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Processes of preparing a desired or intentional composition...
101491, 106 20R, 106 23R, 523161, 428147, 524 77, 524474, 524476, 525123, 5253327, 4273722, 4273855, 4273935, C03C 1700, C09D 500, C09D 1100, D06N 704
Patent
active
058543066
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The printing of rubber articles made from rubber latex.
DISCUSSION OF THE PRIOR ART
The printing of rubber articles made from rubber latex, in particular natural rubber latex, is well known in the art. Balloons have been printed using natural rubber solutions in mineral spirits. These solutions yield a print which can be easily removed by common household detergents and chemicals.
Ink systems for latex rubber, in particular natural latex articles and, more specifically, latex rubber gloves require a degree of chemical resistance not found commercially today. Rubber gloves commonly are exposed to a variety of household chemicals including detergents, bleach, ammonia, oils and grease, polishes, disinfectants, etc. Any decorative system for rubber gloves should be resistant to these common materials. It would therefore be desirable to provide a decorative technique which comprises a printing system for the surface of such rubber articles wherein the printed image is resistant to common household chemicals.
SUMMARY OF THE INVENTION
There is provided a method for printing images on a latex rubber surface which comprises applying an ink containing natural or synthetic rubber, pigment dispersion, and a solvent medium, in particular an aromatically unsaturated solvent medium for said rubber.
A critical feature of the invention is the presence of an agent capable upon cure, of forming a chemically and abrasion resistant, tough flexible structure integrating the rubber of said base coat, where it is present, the rubber of the ink, together with the pigment therein, and the rubber of the latex surface, in at least one of the base coat and the ink. The mechanism if this integration is not fully understood, but its creation of a surprising level of resistance thereby is unquestionably novel.
The preferred integrating agent is, suitably an aryl diisocyanate. Where the rubber containing ink is used over a base coat of natural rubber in such a solvent, the aryl diisocyanate may be either in the base coat or the ink.
A base coat of natural rubber in such a suitable solvent is required, where the rubber in the ink is synthetic rubber. The integrating agent, such as an aryl diisocyanate may be either in the base coat or the ink. However, a portion of the solvent may be replaced by a terpene, a terpenoid or a high boiling ketone suitably having a boiling point over 120.degree. C., such as isophorone or the like.
The efficacy of the printing may be improved by certain pre- and post-printing steps. One such additional step, is heating the printing surface. Another, highly desirable, added step, is placing a base coat upon the printing surface that receives the image. In one embodiment of the process, this base coat is allowed to dry to tackiness before the image is printed. As stated above, this base coat comprises natural rubber in an aromatically unsaturated solvent.
The ink as well as the base coat may be applied using a number of common printing techniques including: gravure printing, flexo printing, screen printing, and pad printing. Pad printing however, has been found to be superior for the inventive purposes, such as: printing individual rubber articles like rubber gloves.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
There is provided a method and a formulation for printing images on latex rubber surfaces. It is desirable that the weight amount of the aryl diisocyanate is between 0.5 and 3.0 times that of the total rubber in solution within the ink or within the base coat where used or both. The rubber may be natural rubber or synthetic rubber. Suitably, the diisocyanate is selected from the group consisting of toluene-, methylene diphenyl- and polymeric methylene diphenyl diisocyanates, and mixtures thereof.
The rubber in the ink may be natural rubber or synthetic rubber such as neoprene rubber or blends thereof. For good printing, the ink, at printing time, should have a viscosity at 20.degree. C. of between 800 and 3000 cps. The use of synthetic rubber in the ink is preferred over natural
REFERENCES:
patent: 2289638 (1942-07-01), Erickson et al.
patent: 4606769 (1986-08-01), Tanaka et al.
patent: 5391685 (1995-02-01), Hitomi et al.
Gugger James
Mattesky Henry
Behr Esq. Omri M.
Herbert Glatt
Niland Patrick D.
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