Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Mixing of two or more solid polymers; mixing of solid...
Reexamination Certificate
2000-11-22
2003-03-25
Nutter, Nathan M. (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Mixing of two or more solid polymers; mixing of solid...
C525S222000, C525S240000, C525S241000
Reexamination Certificate
active
06538068
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to polyethylene-based films and to gloves made of these films.
BACKGROUND OF THE INVENTION
In surgery, in medicine, in the veterinary field, in hairdressing, for applying shampoos and dyes for example, in clean rooms in the electronics industry, and in many applications, disposable gloves are used. The gloves of the present invention are of this type.
Patent EP 643 743 describes gloves made of SBS (styrene-butadiene-styrene) or SIS (styrene-isoprene-styrene) block copolymers. An emulsion of these copolymers is prepared and then a glove-shaped mould is immersed therein. The combination is then left to dry and the glove is obtained.
Patent EP 244 982 describes films consisting (by weight) of 30 to 80% of an ethylene-methyl acrylate copolymer and of 70 to 20% by VLDPE (very low density polyethylene). The proportion of methyl acrylate in the copolymer is between 17 and 22% by weight, the relative density of the VLDPE is between 0.902 and 0.910 and the MFI (melt flow index) is between 0.1 and 10 g/10 min. Preferably, the proportions of the ethylene-methyl acrylate copolymer and of the VLDPE are 50 to 70 and 50 to 30% by weight, respectively. The gloves are produced by welding the film.
It is much simpler to make gloves by welding a film than by immersion of a mould and drying. The films described in EP 244 982 are tacky and must be filled with antiblocking agents and slick agents. In addition, their elongation at break is not high enough.
SUMMARY OF THE INVENTION
The object of the invention is to make films having a high puncture strength, that is to say it must be virtually impossible to puncture them with the fingers and the films must have an elongation at break of at least 100%. These conditions are in fact a minimum in order to prevent the gloves manufactured from these films from tearing when they are slipped onto one's hand.
Another object of the invention is to make films having a silky appearance.
Another object of the invention is to make films exhibiting good elasticity necessary from the point of view of comfort for the purpose of obtaining a much more precise fit on the hand and consequently to make movements more precise. The term “elasticity” is understood to mean within the context of the invention the possibility of stretching the film by 80% of its length at a temperature between 15 and 25° C. for 1 minute, the film returning to within at least 25% of its initial length after stretching. The permanent set is therefore at most 25%.
REFERENCES:
patent: 3639521 (1972-02-01), Hsieh et al.
patent: 3709957 (1973-01-01), Brebner
patent: 4547413 (1985-10-01), Lustig
patent: 6107454 (2000-08-01), Schmieg et al.
patent: 1 321 437 (1993-08-01), None
patent: 0 244 982 (1987-11-01), None
patent: 0 849 323 (1998-06-01), None
patent: WO 94/20574 (1994-09-01), None
Ullman's Encyclopedia of Industrial Chemistry, 5thEd. (1995), vol. A26, pp. 655-659.
Atofina
Nutter Nathan M.
Smith , Gambrell & Russell, LLP
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