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
2001-01-19
2004-03-16
Cain, Edward J. (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...
Reexamination Certificate
active
06706800
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a method of backing carpets, and to carpets backed by the method. More particularly, the present invention relates to a method of backing carpets to be laid chiefly on indoor floorboards or various floor coverings, and to carpets backed by the method.
BACKGROUND OF THE INVENTION
Heretofore, the backing of carpets has been conducted in the following manner: after treating the back of carpets, for example, by a method in which sols prepared by mixing vinyl chloride resins and plasticizers are applied, and cured by heating, a method in which latex compounds are applied, and dried by heating, a method in which mixtures of aqueous emulsions and thermoplastic resin powders are applied, and dried by heating, a method in which thermoplastic resin powders are sprinkled, and melted by heating, a method in which melted thermoplastic resins extruded from extruders are applied, or a method in which thermoplastic resin sheets are laid, and melted by heating, fabrics such as non-woven fabrics are laminated to the treated surfaces of the carpets.
However, the above-described conventional methods for treating carpets to be backed have the following drawbacks. Vinyl chloride resins, which are usually used for backing tile carpets (square carpets), emit dioxin and chlorine gas when carpets backed by using these resins are incinerated as wastes after use. In addition, plasticizers for use with vinyl chloride resins include DOP, DBP, etc., which can pollute the environment. Further, in the case where thick fabrics such as non-woven fabrics are laminated to the back of carpets after applying thereto latices or aqueous emulsions, the resulting laminates show poor air permeability, so that the latices or aqueous emulsions applied cannot be dried in a short time. This makes the production rate lower, and the productivity is thus decreased. In the case of hot melt coating, there is a limitation on the width of carpets to be treated; this is one cause of increase in production cost. Moreover, powders tend to scatter during operation, so that the use of powders is unfavorable from the viewpoint of working environment.
An object of the present invention is to provide a practical method of backing a carpet, using a polymeric emulsion compound that is safe and easy to handle, capable of overcoming the drawbacks with the conventional methods using aqueous systems, that is, capable of attaining rapid drying and curing of the emulsion compound even when the emulsion compound is applied to a thickness of as great as 1 mm or more. Another object of the present invention is to provide a carpet backed by this method.
SUMMARY OF THE INVENTION
The present invention provides a method of backing a carpet, comprising the steps of applying an aqueous emulsion composition described below to the back of a carpet, laminating a fabric to the composition-applied surface of the carpet, and thermally curing and then drying the composition applied; and a carpet backed by this method.
Aqueous Emulsion Composition
An aqueous emulsion composition for use in the present invention comprises:
a high-solid-content emulsion compound comprising:
(A) 100 parts by weight (solid basis) of at least one latex or emulsion selected from the group consisting of styrene-butadiene copolymer latices, acrylic resin emulsions, ethylene-vinyl acetate copolymer emulsions, acrylonitrile-butadiene copolymer latices, urethane resin emulsions, and natural rubber latices,
(B) 0.3 to 2 parts by weight of a dispersing agent,
(C) 0.5 to 5 parts by weight of a crosslinking agent,
(D) 0.1 to 4 parts by weight of an anti-foaming agent, and
(E) 100 to 600 parts by weight of at least one powdered filler selected from the group consisting of calcium carbonate, aluminum hydroxide, silica sand, and barium sulfate; and
(F) 0.5 to 30 parts by weight of a polyisocyanate compound having reactive isocyanate group, wherein the polyisocyanate compound is added to the high-solid-content emulsion compound.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
According to the present invention, the aqueous emulsion composition is obtained, preferably just before use, by adding the polyisocyanate compound, which serves as a curing agent, to the high-solid-content emulsion compound, and used for backing a carpet. The polyisocyanate compound reacts with water contained in the emulsion compound to cure the aqueous emulsion composition, so that the aqueous emulsion composition applied is dried quickly. Therefore, even when the aqueous emulsion composition is applied to the back of a carpet to a thickness of as great as 1 mm or more, high productivity can be attained regardless of the thickness of a fabric such as a non-woven fabric laminated to the back of the carpet. A backed carpet can thus be inexpensively obtained. Moreover, even when the aqueous emulsion composition is applied to the back of a carpet to a thickness of as great as 1 mm or more, the obtained carpet shows elasticity without using any plasticizer. In addition, when the obtained carpet is burned, it scarcely fumes and it emits only small amounts of toxic gasses. A backed carpet favorable from the viewpoint of environmental pollution can thus be successfully obtained by the method of the invention.
Aqueous Emulsion Composition
Component (A)
Component (A) for use in the aqueous emulsion composition of the present invention is at least one base rubber emulsion selected from the group consisting of styrene-butadiene copolymer latices, acrylic resin emulsions, ethylene-vinyl acetate copolymer emulsions, acrylonitrile-butadiene copolymer latices, urethane resin emulsions, and natural rubber latices.
Component (A) is used in the aqueous emulsion composition of the invention as a base rubber. This component serves as a binder and as an anchorage for carpet yarn, and imparts anti-folding properties and elasticity to a carpet.
Styrene-butadiene copolymer latices useful for component (A) are, for instance, SBR latices obtainable by copolymerization of 15 to 85% by weight, preferably 25 to 50% by weight of styrene with 85 to 15% by weight, preferably 75 to 50% by weight of butadiene, having glass transition temperatures of −60 to −10° C., preferably −50 to −15° C. The SBR latices may be carboxy-modifed ones obtained by copolymerizing the above two monomers and not more than 8% by weight, preferably about 0.5 to 5% by weight of, for example, acrylic, methacrylic, itaconic, phthalic or maleic acid. The SBR latices may also be amide-modified ones obtained by copolymerizing the above two monomers and (meth)acrylic amide or the like.
Acrylic resin emulsions that are used as component (A) are preferably acrylic ester-methacrylic acid-styrene copolymer emulsions having glass transition temperatures of −60 to −10° C., preferably −50 to −15° C., obtained by emulsion-copolymerizing acrylic esters, methacrylic acid, and styrene. Examples of acrylic esters useful herein include those ones having 1 to 4 carbon atoms, such as methyl acrylate, hydroxyethyl acrylate and butyl acrylate. The acrylic ester/methacrylic acid/styrene ratio for copolymerization is (40 to 90% by weight)/(60 to 10% by weight)/(10 to 60% by weight), preferably (50 to 80% by weight) (50 to 20% by weight) (10 to 30% by weight) The acrylic resin emulsions may be carboxy-modifed ones obtained by copolymerizing the above three monomers and not more than 8% by weight, preferably about 0. 5 to 5% by weight of, for example, acrylic, methacrylic, itaconic, phthalic or maleic acid. The acrylic resin emulsions may also be amide-modified ones obtained by copolymerizing the above three monomers and (meth)acrylic amide or the like.
Ethylene-vinyl acetate emulsions that can be used as component (A) are EVA emulsions obtainable by copolymerization of 10 to 40% by weight, preferably 15 to 30% by weight of ethylene with 90 to 60% by weight, preferably 85 to 70% by weight of vinyl acetate, having glass transition temperatures between −35° C. and +10° C., preferably between −30° a
Seimiya Kenzi
Tanno Teturo
Cain Edward J.
Emulsion Technology Co., LTD
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