Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – At least one aryl ring which is part of a fused or bridged...
Reexamination Certificate
1999-06-10
2001-06-19
Sanders, Kriellion (Department: 1714)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
At least one aryl ring which is part of a fused or bridged...
C524S434000, C524S436000, C428S704000
Reexamination Certificate
active
06248821
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a halogen-free flameproof mesh sheet suitable for being used outdoors such as in a construction work site or engineering work site for a long time.
2. Description of Related Art
A tendency toward an increase in the number of buildings having a large number of stories has been seen recently in the construction industry. Meanwhile, there is also an increase in the number of houses having a small number of stories. It is generally obligatory to lay flameproof mesh sheets in the construction of houses having a small number of stories, as well as scattering prevention flameproof mesh sheets may also be required in these buildings for safety. Regulations regarding such flameproofing are becoming more and more strict.
Currently used flameproof mesh sheets and scattering prevention flameproof mesh sheets can be produced for example, by weaving gray yarn prepared by coating polyester, nylon or polypropylene multi-filament fibers with a vinyl chloride-based paste resin composition and heating. The obtained gray cloth is then subjected to further heating. Alternatively, such yarn can be prepared by coating gray cloth prepared by weaving multi-filament fibers with a vinyl chloride-based paste resin composition and heating, and processing the obtained gray cloth to a desired shape.
The resin composition for coating fibers and cloth comprises for example, a chlorine-containing vinyl chloride resin as the resin and a chlorine-based flame retardant such as chlorinated paraffin, a bromide-based flame retardant such as decabromodiphenyl oxide, or an inorganic flame retardant such as antimony trioxide as a flame retardant (see, for example, Examined Japanese Patent Publication Nos. 52-41786, 53-18065 and 61-9430, as well as Plastics, February, 1991 which are all incorporated herein by reference in their entireties).
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 environmental preservation.
Japanese Laid-Open Patent Publication No. 61-223045 proposes kneading red phosphorus and ammonium phosphate into a polyolefin to prevent corrosion by halogen contained in a halogen-containing compound flame retardant. However, a flame retardant prepared by dispersing ammonium polyphosphate or a metal hydroxide into an aqueous dispersion of an ethylene-vinyl acetate copolymer, an ethylene-vinyl acetate-vinyl versatate copolymer or an ethylene-vinyl acetate-acrylic ester copolymer, or a dispersion consisting of the above dispersion and a polyurethane aqueous dispersion is not known.
The inventors of the present invention previously proposed a halogen-free flame retardant comprising an aqueous dispersion of a polyolefin resin in Japanese Patent Application No. 9-225464 (incorporated herein by reference in its entirety). Although this flame retardant provides an excellent effect, it has a tendency to increase in viscosity during storage over time.
The present inventors also previously proposed a halogen-free flame retardant containing an aqueous dispersion of an ethylene-vinyl acetate copolymer of 10 to 95 parts by weight of vinyl acetate and the balance consisting of ethylene in Japanese Patent Application No. 9-312550 (incorporated herein by reference in its entirety). Although this flame retardant provides excellent function and effect, a product thereof has a red tint because red phosphorus is used and it is difficult to color it opaque white or a light vivid color, even by adding titanium oxide or the like. The present invention improves the color and flame retardancy of the flame retardant of JP 9-312550. An opaque white or light vivid color flameproof mesh sheet has been desired in the application field of flameproof mesh sheets.
SUMMARY OF THE INVENTION
It is an object of the present invention, which has been made in view of the above situation, to provide a flame retardant for halogen-free flameproof mesh sheets which does not substantially experience an increase in viscosity during storage, can generally be colored any color, is generally lustrous and flexible, and does not generate harmful halogen gas at the time of combustion, as well as flameproof mesh sheet comprising the same.
In accordance with these and other objects, there is provided a flame retardant suitable for use in sheets comprising a polyolefin resin aqueous dispersion having a resin solid content of 25-75 wt %, 40 to 130 parts by weight of an ammonium polyphosphate compound based on 100 parts by weight of said polyolefin resin aqueous dispersion, and 60 to 150 parts by weight of a metal hydroxide based on 100 parts by weight of the solid content of said polyolefin resin aqueous dispersion.
Additional objects, features and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects, features and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out in the appended claims.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
The present invention relates to: a flame retardant for mesh sheets which comprises 40 to 130 parts by weight of an ammonium polyphosphate compound and 60 to 150 parts by weight of a metal hydroxide based on 100 parts by weight of the solid content of a polyolefin resin aqueous dispersion having a resin solid content of 25 to 75 wt %. Particularly, the polyolefin resin aqueous dispersion can be at least one selected from (i) an aqueous dispersion of an ethylene-vinyl acetate copolymer of 10 to 95 wt %, preferably 15 to 95 wt %, of vinyl acetate and the balance consisting of ethylene, having a resin solid content of 25 to 75 wt %, or preferably 30 to 75 wt %, (ii) an aqueous dispersion of an ethylene-vinyl acetate-vinyl versatate copolymer of 5 to 30 wt % of ethylene, 15 to 70 wt %, or preferably 30 to 70 wt %, of vinyl acetate and 25 to 75 wt %, or preferably 25 to 65 wt %, of vinyl versatate, having a resin solid content of 30 to 70 wt %, and (iii) an aqueous dispersion of an ethylene-vinyl acetate-acrylic ester copolymer of 5 to 30 wt % of ethylene, 10 to 75 wt %, or preferably 30 to 70 wt %, of vinyl acetate and 20 to 85 wt % of acrylic ester, having a resin solid content of 25 to 75 wt %, or preferably 40 to 70 wt %.
Any polyolefin resin aqueous dispersion can be used. An aqueous dispersion of an ethylene-vinyl acetate copolymer which is an olefin resin, an aqueous dispersion of an ethylene-vinyl acetate-vinyl versatate copolymer or an aqueous dispersion of an ethylene-vinyl acetate-acrylic ester copolymer are advantageous as a base material in the present invention. This is because such dispersions tend to fully impregnate multi-filament fibers and cloth with the flame retardant and uniformly coat them therewith. Aqueous dispersions that provide easy coating by impregnation are desirable for use in the present invention.
Suitable ethylene-vinyl acetate copolymers used in the present invention include, for example, a copolymer of 10 to 95 wt % of vinyl acetate and the balance consisting of ethylene. Suitable aqueous dispersions of the ethylene-vinyl acetate copolymer preferably have a solid content of 25 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, as exemplified for example, by V-200 and V-100 (of Mitsui Petrochemical Industries, Ltd.), and S-200, S-467, S-500, S-706, S-455, S-752 and S-753 (of Sumitomo Chemical Company, Ltd.).
Since an ethylene-vinyl acetate copolymer has a —OCO—CH
3
group and contains a substantial amount of oxygen, the flame retarding effect thereof is generally large when it is used in combination of ammonium polyphosphate. Suitable ethylene-vinylacetate-vinyl versatate copolymers useful in the present invention include, for example, a copolymer of 5 to 30 wt % of ethylene, 15 to 70 wt %, or prefer
Kamiya Kuniaki
Nozaki Saiji
Kyowa Kabushiki Kaisha
Rader Fishman & Grauer
Sanders Kriellion
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