Stock material or miscellaneous articles – Composite
Reexamination Certificate
1998-12-04
2001-11-06
Hess, Bruce H. (Department: 1774)
Stock material or miscellaneous articles
Composite
C428S365000, C428S368000, C442S003000, C442S027000, C442S043000, C442S050000, C442S054000, C442S058000
Reexamination Certificate
active
06312810
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a halogen-free flameproof mesh sheet used outdoors, for example, at a construction site, for a long time.
In recent years, the height or number of stories of buildings is being increased in the construction industry. Meanwhile, the number of houses having a small number of stories is being increased. There buildings or houses must be covered with flameproof mesh sheets for safety and protection, flameproof mesh sheets for few-storied houses, and scattering prevention flameproof mesh sheets, and such regulations are becoming more and more strict.
Currently used flameproof mesh sheets and scattering prevention flameproof mesh sheets are produced by coating multifilament fibers of, for example, polyester, nylon or polypropylene, with a vinyl chloride-based paste resin composition, to prepare original yarn, which is then heated, and, after weaving the yarn into a cloth, heating the cloth to provide a mesh sheet. In another method, a mesh sheet is produced by coating a fabric prepared by weaving multifilament fibers with a vinyl chloride-based paste resin composition, heating the coated fabric, and then forming it into a desired shape.
In the resin composition with which the fibers and fabric are coated, a vinyl chloride resin containing chlorine is used as a resin, and a chlorine-based flame retardant such as chlorinated paraffin, bromine-based flame retardant such as decabromodiphenyl oxide or inorganic flame retardant such as antimony trioxide is used as a flame retardant (as disclosed in Examined Japanese Patent Publication Nos. 52-41786, 53-18065 and 61-9430, Plastics, February, 1991).
In recent years, it has been globally demanded to avoid the use of resins and flame retardants containing elemental halogen which generates harmful gas at the time of combustion, from the viewpoint of the environmental preservation of the earth.
It is proposed in Japanese Laid-open Patent Publicationn No. 61-223045 that red phosphorus and ammonium polyphosphate are kneaded into polyolefin to prevent corrosion caused by halogen contained in a flame retardant made of a halogen-containing compound. However, there has not been known a flame retardant prepared by dispersing red phosphorus and ammonium phosphate in an aqueous dispersion of an ethylene-vinyl acetate copolymer, or an aqueous dispersion comprising the above aqueous dispersion and an aqueous dispersion of an &agr;-olefin copolymer and/or an aqueous dispersion of polyurethane.
The inventor of the present invention has proposed in Japanese Patent Application No. 9-225464 a halogen-free flame retardant comprising an aqueous dispersion of a polyolefin resin as a flame retardant. This flame retardant yields an excellent effect, but its viscosity tends to increase due to chronological changes during storage thereof.
The inventor of the present invention has also proposed in Japanese Patent Application No. 9-312550 a halogen-free flame retardant comprising an aqueous dispersion of an ethylene-vinyl acetate copolymer containing 10 to 90 parts by weight of vinyl acetate. While this flame retardant has excellent effect and function, the present invention provides further improvements in the gloss, flexibility and flame retardancy over the proposed flame retardant. Flameproof mesh sheets having significantly improved gloss and flexibility have been strongly desired depending upon the field in which the sheets are used.
SUMMARY OF THE INVENTION
The present invention has been developed in view of the above situations. It is therefore an object of the present invention to provide a flame retardant for halogen-free flameproof mesh sheets, which does not suffer from an increase in its viscosity during storage, has excellent gloss and flexibility, and does not generate harmful halogen gas at the time of combustion, and to provide a flameproof mesh sheet using the flame retardant.
The present invention relates to a flame retardant for mesh sheets, which is prepared by mixing 1.5 to 15 parts by weight of red phosphorus, 10 to 50 parts by weight of an ammonium polyphosphate compound, and 3 to 30 parts by weight of an organic phosphate, with 100 parts by weight of the solid content of an aqueous dispersion of an ethylene-vinyl acetate copolymer having a vinyl acetate content of 10 to 95 wt % and a resin solid content of 25 to 75 wt %.
The present invention also relates to a flame retardant for mesh sheets, which is prepared by mixing an aqueous dispersion of an &agr;-olefin copolymer having a solid content of 20 to 45 wt %, with an aqueous dispersion of an ethylene-vinyl acetate copolymer having a vinyl acetate content of 10 to 95 wt % and a resin solid content of 25 to 75 wt %, in a solid content weight ratio of 10:90 to 70:30, and adding 1.5 to 15 parts by weight of red phosphorus, 10 to 50 parts by weight of an ammonium polyphosphate compound, and 3 to 30 parts by weight of an organic phosphate, with respect to 100 parts by weight of the total resin solid content. Furthermore, the present invention relates to a flame retardant for mesh sheets, which is prepared by mixing an aqueous dispersion of polyurethane having a solid content of 25 to 70 wt %, with an aqueous dispersion of an ethylene-vinyl acetate copolymer having a vinyl acetate content of 10 to 95 wt % and a resin solid content of 25 to 75 wt %, in a solid content weight ratio of 10:90 to 90:10, and adding 1.5 to 15 parts by weight of red phosphorus, 10 to 50 parts by weight of an ammonium polyphosphate compound, and 3 to 30 parts by weight of an organic phosphate, with respect to 100 parts by weight of the total resin solid content.
Also, the present invention relates to a flame retardant for mesh sheets prepared by mixing an aqueous dispersion of an &agr;-olefin copolymer having a solid content of 20 to 45 wt % and an aqueous dispersion of polyurethane having a solid content of 25 to 70 wt %, with an aqueous dispersion of an ethylene-vinyl acetate copolymer having a vinyl acetate content of 10 to 95 wt % and a resin solid content of 25 to 75 wt %, in a solid content weight ratio of 10:10:80 to 50:80:10, and adding 1.5 to 15 parts by weight of red phosphorus, 10 to 50 parts by weight of an ammonium polyphosphate compound, and 3 to 30 parts by weight of an organic phosphate, with respect to 100 parts by weight of the total resin solid content.
The red phosphorus and ammonium polyphosphate compound as indicated above may be micro-capsulated.
The present invention also relates to a flameproof mesh sheet produced by weaving yarn comprising, for example, multifilament fibers, which yarn is impregnated and coated with the flame retardant for mesh sheets of the present invention.
PREFERRED EMBODIMENTS OF THE INVENTION
According to the present invention, an aqueous dispersion of an ethylene-vinyl acetate copolymer is used as a base material because multifilament fibers and fabric are fully impregnated with a flame retardant and uniformly coated with the flame retardant. The aqueous dispersion makes impregnation and coating easy.
The ethylene-vinyl acetate copolymer used in the present invention desirably contains 10 to 95 wt % of vinyl acetate, and the aqueous dispersion of the ethylene-vinyl acetate copolymer preferably has a solid content of 27 to 75 wt %, a particle diameter of 0.1 to 15 &mgr;m, a viscosity of 50 to 9,000 cp and a pH of 4 to 9. For instance, V-200 and V-100 (manufactured by Mitsui Petrochemical Industries, Ltd.), S-301, S-500, S-706, S-751 and S-752 (of Sumitomo Chemical Company, Ltd.), and others are suitably used.
Since the ethylene-vinyl acetate copolymer has a group represented by —OCO—CH
3
and a large amount of oxygen, the copolymer, when used in combination with red phosphorus and ammonium polyphosphate, provides a great flame retarding effect.
In the present invention, an &agr;-olefin copolymer can be used along with the aqueous dispersion of the ethylene-vinyl acetate copolymer. A dispersion of the &agr;-olefin copolymer preferably has a solid content of 20 to 45 wt %, a particle diameter of 1 to 10 &mgr;m, a pH of
Kamiya Kuniaki
Nozaki Saiji
Hess Bruce H.
Rader Fishman & Grauer
Saiji Nozaki
Shewareged B.
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