Removal of protein from natural rubber latex articles

Details Removal of protein from natural rubber latex articles Removal of protein from natural rubber latex articles

1997-12-08

2000-08-22

Merriam, Andrew E. C.

Synthetic resins or natural rubbers -- part of the class 520 ser

Synthetic resins

Treating polymer containing material or treating a solid...

528490, 528932, 523332, 524925, 435209, 435269, C08C 104

Patent

active

061074551

DESCRIPTION:

BRIEF SUMMARY
TECHNICAL FIELD

This invention relates to the production of natural rubber latex articles having a low protein content.


BACKGROUND ART

Articles made from natural rubber latex generally contain protein, and this may give rise to a variety of undesirable effects in the finished article, including allergic reactions in articles intended for use in contact with human skin, e.g. surgical gloves, medical catheters, household gloves and condoms.
The protein content in rubber latex articles is commonly expressed in two different ways: as total extractable protein (EP) and as protein antigen. The total extractable protein (EP) can be measured, e.g., by the Lowry protein assay. The protein antigen expresses the allergenicity of the protein in the article; it may be measured, e.g., by the ELISA assay method.
A number of methods have been proposed to reduce the protein content or to alleviate the allergic reactions in articles made of natural rubber latex. Thus, Novo Nordisk A/S in Research Disclosure, Mar. 10, 1992, No. 335102 discloses that treatment of latex or latex goods with a protease is effective for changing the proteins to non-antigens and also for reducing the amount total protein in latex goods such as gloves. AU-A-44456/93 (Sumitomo Rubber Ind. & Kao Corp.) discloses a treatment of natural rubber latex with a protease, an anionic surfactant and/or a non-ionic surfactant. AU-A-63069/94 and AU-A-63070/94 (both to Sumitomo Rubber Ind. & Kao Corp.) disclose a treatment of a natural rubber latex with a protease and a surfactant, followed by the addition of, an anionic, amphoteric or non-ionic surfactant, oligomer or polymer, to improve the mechanical stability.


SUMMARY OF THE INVENTION

Surprisingly, we have found that the extractable protein content of a rubber latex article can be reduced by washing the article with a solution containing a soluble silicate. In a highly preferred embodiment, the solution also comprises a protease which serves to further reduce the extractable protein content and particularly to make the remaining protein less antigenic. With a combination of silicate and protease it is possible to reduce the protein antigen content to below the detection limit of the commonly used ELISA method.
Accordingly, the invention provides a method for producing a natural rubber latex articles, comprising washing the article with a solution comprising a soluble silicate and optionally a protease.
Another aspect of the invention provides a composition comprising a protease and a soluble silicate, in amounts which make the composition effective for use in lowering the extractable protein content of an article made of natural rubber latex.


DETAILED DESCRIPTION OF THE INVENTION

The process of the invention is applicable to reducing the content of extractable protein in any article made of natural rubber article, particularly latex-dipped products. Some specific examples are surgical gloves, medical catheters, household gloves and condoms.
The soluble silicate may be a crystalline alkaline silicate or a colloidal neutral silicate. It is preferably an alkali metal silicate, particularly a sodium silicate, preferably having a ratio of Na.sub.2 O/SiO.sub.2 in the range from 2:1 to 1:3.75. Some specific examples are:


______________________________________ Chemical name Empirical formula Na.sub.2 O/SiO.sub.2 ratio ______________________________________ Sodium orthosilicate Na.sub.4 SiO.sub.4 2:1 Sodium sesquisilicate Na.sub.6 Si.sub.2 O.sub.7 1.5:1 Sodium metasilicate Na.sub.2 SiO.sub.3 1:1 Colloidal neutral silicate -- 1:1.6 to 1:3.75 ______________________________________
A suitable concentration of the soluble silicate is 0.2-10 g/l, preferably 1-5 g/l, in the solution used in the process of the invention or 10-90% by weight of the composition of the invention.
Any type of protease known to be effective on latex extractable protein or effective as a detergent additive can be used in the invention. An alkaline protease is preferred, e.g. an alkaline prote

REFERENCES:
patent: 2116089 (1938-05-01), Wallerstein
patent: 4526698 (1985-07-01), Kuroda et al.
patent: 4620936 (1986-11-01), Kielman et al.
patent: 5622646 (1997-04-01), Scialla et al.

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