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
2000-02-07
2001-07-03
Yoon, Tae H. (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...
C524S284000, C524S523000, C528S486000
Reexamination Certificate
active
06255381
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a process for manufacturing a highly efficient antislipping agent composed of acrylic copolymers based on small amounts of solid content; wherein two kinds of acrylic latexes composed of small amounts of solid content are prepared by using pertinent acrylic monomers in low or high glass transition point side, being well blended and homogenized by neutralizing with ammonia water.
2. Description of the Related Art
According to the composition of antislipping agents in the first stage, some hot-melt adhesives were coated along several lines on the surfaces of packaging boxes made of craft paper, the adhesives proved to have antislippling effects owing to its initial strong adhesive strength when stacking packaging boxes and some disadvantages were recognized in that a) separation between packaging boxes were difficult, and b) after separation, the packaging surfaces are torn or stained, thus inflicting some damages to the surfaces due to extremely strong adhesive strength [Japanese Patent Unexamined Publication No. 1-183596(1989)].
To be free from weak points, some antislipping agents as a hyblid of inorganic and organic substances were developed:
a) Inorganic substance included silicahydrosol containing 20 to 30 wt % of colloidal silica whose particle size was in the range of 10 to 20 &mgr;m. Silicahydrosol in liquid phase was useful not to be whitened in handling when coated or dried. Now that said the size was too small, however, its homogeneous dispersion was so difficult that desirable antislipping effects could not be gained [Canadian Patent No. 1,156,803(1980), Japanese Patent Unexamined Publication Nos. 2-245086 (1990) and 4-303653 (1992)].
b) Organic substance composed of stylene and acrylic acid as well as some composition with reactive groups proved to have less antislipping effects [Japanese Patent Unexamined Publication No. 57-565989 (1982)].
Further, some antislipping agents containing inorganic and organic substances concurrently included a composition in which synthetic resin binder, using silica powder and poly(acrylamide) treated with nonionic cellulose derivatives as a protective colloid, was dispersed in water. After the agents were coated or dried, they showed good antislipping effects but when used repeatedly, its antislipping effects become deteriorated and in particular, a poor dispersion of antislipping agent itself affected its storage stability badly [Japanese Patent Unexamined Publication No. 59-4460 (1984)].
In view of facts above-mentioned, there were some methods in which a part of resin with adhesive strength was blended to ethylene-vinyl acetate copolymer emulsion, followed by additional blending of silica, fillers and releasing agents. However, the methods proved to have insufficient antislipping effects and when packaging boxes were separated, their surfaces were torn off or contaminated owing to its extremely strong adhesive strength or the lack of reutilization [Japanese Patent Unexamined Publication No. 54-65385(1988), 62-70461(1987), 62-110997(1987) and 4-198373(1992)].
Recently, some latex-typed antislipping agents using nonionic surfactants as a emulsifier were developed. Each particle in the latex consists of both a core as a hard segment and a shell as a soft segment and when drying, it showed good antislipping properties. But since there was no distinction between hard and soft segments with increasing of solid content in the latex, it was still difficult to prepare a latex with storage stability [Japanese Patent Unexamined Publication No. 4-306273(1992)].
SUMMARY OF THE INVENTION
The object of this invention is to provide a process for manufacturing an antislipping agent with high viscosity, latex-typed compounds with storage stability, being characterized by the facts that an antislipping agent with small amounts of solid content mentioned in the above has a good harmony between hard and soft segments as well as its storage stability.
This invention is to provide a process for manufacturing an antislipping agent characterized by comprising steps of;
1) through the emulsion polymerization between acrylic monomers of 20 to 80 wt % with glass transition point(Tg) in the range of −85 to −5° C. and acrylic monomers of 20 to 80 wt % with Tg in the range of 8 to 153° C., an acrylic latex with relatively low scope of Tg is prepared;
2) through another emulsion polymerization in another container between acrylic monomers of 10 to 60 wt % with Tg in the range of 8 to 153° C. and acrylic monomers of 40 to 90 wt % with Tg in the range of −85 to −5° C. an acrylic latex with relatively high scope of Tg is prepared; and
3) the acrylic latex mentioned in the step 2) of 5 to 60 wt parts is chemically blended with that in the step 1) of 100 wt parts, and the blending is completed by neutralizing with ammonia water.
DETAILED DESCRIPTION OF THE INVENTION
This invention relates to a process for manufacturing an antislipping agent composed of small amounts of solid content, wherein an acrylic latex having low Tg is blended in a certain ratio with an acrylic latex having high Tg and after neutralization, and if necessary, an inorganic compound and its blending/dipersing agents may be added to the blend.
More detailed process for manufacturing an acrylic antislipping agents of this invention is as follows:
In an effort to prepare an acrylic latex with flexibility according to this invention, acrylic monomers(viscosity: 10 to 30 cps) having low Tg in the range of −85 to −5° C. are selected and these monomers provide adhesive strength to an antislipping agent of this invention.
More specfically, the monomers include ethylacrylate, n-butylacrylate, isopropylacrylate, 2-ethylhexylacrylate, n-hexylmetacrylate, laurylmetacrylate, 2-hydroxyethyllacrylate and hydroxypropylacrylate, and one or more acrylic monomers may be used. In case of preparing an acrylic latex having low Tg in the range of −85 to −5° C., the content of monomers should be preferably in the range of 20 to 80 wt %. Should the content be less than 20 wt %, an antislipping agent itself, prepared through emulsion polymerization, lacks the antislipping effects due to the hardness and insufficient tacky property but if the content exceed 80 wt %, its insufficient, cohesive force due to the excessive flexibility may lead to decreasing the antislipping effects, while having high tacky property when dried.
Further, in order to prepare an acrylic latex with good storage stability, an aqueous cellulose is used to enhance the viscosity of an dispersed solution. More specifically, the celluloses mentioned here include methycellulose, ethylcellulose, hydroxyethylcellulose and hydroxypropylmethylcellulose. Hence, one or more celluloses may be used with 0.05 to 20 wt parts in proportion to 100 wt parts of water, a polymerization solvent.
In general, when small amounts of monomers are under emulsion polymerization, far less content of celluloses designed for the dispersion may be responsible for a latex without dispersion stability.
However, in the event that celluloses are employed to reaction solvents in the range of scope above-mentioned, the viscosity in reaction solution increased and acrylic monomers dropped as a liquid phase are favorably dispersed, showing the polymerization with dispersion stability. An acrylic latex, so formed, is favorable in terms of its storage stability and despite less solid content of the latex, the antislipping effects prove to be desireable. Hence, if the content of celluloses for dispersion is less than 0.05 wt parts, there are little dispersion effects associated with the viscosity of reaction solvent and the emulsion polymerization is not well progressed. Nevertheless, if the content of celluloses for dispersion exceeds 20 wt parts, the disperse force is on the contrary decreased due to high viscosity of the reaction solution in emulsion polymerization.
In order to provide the hardness to an
Jang Ja-Soon
Park In-Hwan
Seol Sang-Won
Suh Jung-Mok
Finnegan Henderson Farabow Garrett & Dunner LLP
Korea Research Institute of Chemical Technology
Yoon Tae H.
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