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
2000-11-28
2003-04-15
Wu, David W. (Department: 1713)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Mixing of two or more solid polymers; mixing of solid...
C524S557000, C524S812000, C524S503000, C524S501000, C525S330600, C526S304000
Reexamination Certificate
active
06548605
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an aqueous emulsion composition and an adherent composition and, more particularly, to an aqueous emulsion composition and an adherent composition suitably used as a primer or adhesive.
2. Description of the Prior Art
Organic solvent adhesives are generally in wide use as an adherent composition used for adhesive bonding of a variety of molded products such as plastic films, plastic sheets, plastic foams, fibers, synthetic leathers, and metals.
The organic solvent adhesives have high adhesion strength for relatively rigid molded products, so that they are used for a variety of applications, while on the other hand, they have disadvantages of being at risk of catching fire and being not so desirable in environmental sanitation. In view of these disadvantages, in recent years, aqueous adhesives have been increasingly developed as a substitute for the organic solvent adhesives.
Known as the aqueous adhesives are adherent compositions comprising ethylene-vinyl acetate copolymer containing an aqueous emulsion, for example.
However, the conventional aqueous adhesives that have been developed so far, including the adherent composition comprising ethylene-vinyl acetate copolymer containing an aqueous emulsion, are still insufficient in adhesion strength for adhesive bonding the molded products and thus are practically unusable.
It is the object of the present invention to provide an aqueous emulsion composition that has high adhesion strength for a variety of materials so that it can be used for the adhesive bonding of even molded products and to provide an adherent composition comprising the aqueous emulsion composition.
SUMMARY OF THE INVENTION
An aqueous emulsion composition of the present invention comprises a carboxyl modified resin of a saponified ethylene-vinyl acetate copolymer and a surface active agent.
The aqueous emulsion composition of the present invention can be suitably used as an adherent composition, such as a primer and an adhesive.
It is preferable that in the aqueous emulsion composition of the present invention, the carboxyl modified resin of the saponified ethylene-vinyl acetate copolymer contains the vinyl acetate in the range of 20 to 50 weight % based on the weight of raw materials used to produce the ethylene-vinyl acetate copolymer.
It is preferable that the carboxyl modified resin of the saponified ethylene-vinyl acetate copolymer has a hydroxyl value of 0-250 KOHmg/g and an acid value of 2-150 KOHmg/g.
The aqueous emulsion composition of the present invention may further comprise an unsaturated ethylene monomer or a photo polymerization initiator. The aqueous emulsion composition of the present invention may further comprise chlorinated polyolefin contained resin.
It is preferable that in the aqueous emulsion composition of the present invention, the surface active agent contains an oxyethylene group. Further, it is preferable that the surface active agent contains an anionic group. Also, it is preferable that the aqueous emulsion composition contains the surface active agent in the range of 2 to 24 parts by weight per 100 parts by weight of the carboxyl modified resin of the saponified ethylene-vinyl acetate copolymer.
An adherent composition of the present invention comprises the above-mentioned aqueous emulsion composition.
The adherent composition of the present invention comprising the aqueous emulsion composition has high adhesive strength for a variety of materials, for adhesive bonding a variety of molded products, such as plastic films, plastic sheets, plastic foams, fibers, synthetic leathers and metals. Due to the aqueous composition, the composition has little risk to catch fire and can provide good sanitation in the environment.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
The aqueous emulsion composition of the present invention comprises carboxyl modified resin of saponified ethylene-vinyl acetate copolymer and surface active agent.
The carboxyl modified resin of saponified ethylene-vinyl acetate copolymer used in the present invention (hereinafter it is sometimes referred to as “C-HEVA”) can be produced by partly saponifying an ethylene-vinyl acetate copolymer (hereinafter it is sometimes referred to as “EVA”) and then modifying it by use of acid, as described, for example, by Japanese Patent Publication No. Hei 5(1993)-26,802 disclosing the production process.
The ethylene-vinyl acetate copolymer can be manufactured by a known method such as a high-pressure method and an emulsification method and is available as raw material. According to the present invention, the content of the vinyl acetate used is preferably in the range of 20 to 50 weight %, or further preferably in the range of 25 to 45 weight %, as the ratio of vinyl acetate to the raw material composition. The vinyl acetate copolymer used preferably has the melt index (g/10 min (190° C., 2,160 g) based on ASTM D-1238 (the melt indexes occurring in the following are all the same as this)) of 0.1-500, or further preferably 1-300. The content of vinyl acetate less than that may cause reduction of flexibility and thus reduction of adhesion at low temperature. On the other hand, the content of vinyl acetate more than that may cause reduction of heat resistance.
The ethylene-vinyl acetate copolymer is saponified in the following processes. First, the ethylene-vinyl acetate copolymer is dissolved in organic solvent having a boiling point of not less than 50° C. The organic solvents that may be used include, for example, aromatic hydrocarbons such as benzene, toluene, o-xylene, m-xylene, ethyl benzene, and propyl benzene, and aliphatic or alicyclic hydrocarbons such as n-hexane and cyclohexane. Of these organic solvents, aromatic hydrocarbon, such as xylene and toluene, being capable of causing the azeotropic boiling of water or organic solvent having a boiling point of 100-200° C. are preferably used. While only a required amount of organic solvent to dissolve the ethylene-vinyl acetate copolymer may be used, 150-500 parts by weight of organic solvent per 100 parts by weight of ethylene-vinyl acetate copolymer should preferably be used to allow smooth progress of the next reaction.
Then, after a lower alcohol is added to the solution of ethylene-vinyl acetate copolymer thus prepared, alkali alcoholate is added thereto as catalyst in the presence of a specified amount of water, for saponification reaction.
The lower alcohols that may be used include, for example, methyl alcohol, ethyl alcohol, propyl alcohol, isopropyl alcohol, butyl alcohol, isobutyl alcohol, sec-butyl alcohol and tert-butyl alcohol. Methanol can preferably be cited as the lower alcohol. Preferably, the lower alcohol has the number of moles 0.1-10 times, or further preferably 1-8 times, that of the vinyl acetate contained in the ethylene-vinyl acetate copolymer, though it varies depending on the desired saponification of the ethylene-vinyl acetate copolymer.
The alkali alcoholates that may be used as the catalyst include, for example, alcoholate of alkali metal such as sodium methoxide, sodium ethoxide, potassium methoxide, potassium ethoxide, lithium methoxide and potassium-t-butoxide. Preferably, the alkali alcoholate has the number of moles 0.01-1 times, or further preferably 0.01-0.2 times, that of the vinyl acetate contained in the ethylene-vinyl acetate copolymer, though it varies depending on the desired saponification of the ethylene-vinyl acetate copolymer.
For example, 0.1-3 moles of water per mole of alkali alcoholate is preferably used with alkali alcoholate.
The saponification may be performed by using the known condition that after a specified time (e.g. 0.5-3 hours) passing at a specified temperature (e.g. 40-60° C.), water is added to reactive system to terminate the reaction. The degree of saponification is in the order of 10-90%, though no particular limitation is imposed thereon.
Then, the partly saponified ethylene-vinyl acetate copolymer thus produced (hereinafter it is sometimes referred to as “HEVA”) is mod
Morita Hirofumi
Okatani Susumu
Hu Henry
Mitsui Takeda Chemicals Inc.
Wenderoth , Lind & Ponack, L.L.P.
Wu David W.
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