Compositions – Compositions containing a single chemical reactant or plural... – Organic reactant
Reexamination Certificate
2000-12-01
2004-03-16
Anthony, Joseph D. (Department: 1714)
Compositions
Compositions containing a single chemical reactant or plural...
Organic reactant
C252S182280, C252S182130
Reexamination Certificate
active
06706208
ABSTRACT:
BACKGROUND OF THE INVENTION
A. Technical Field
The present invention relates to a stabilized hydroxyalkyl (meth)acrylate.
B. Background Art
Hydroxyalkyl (meth)acrylate is very high in reactivity and is easily polymerized, and hence it is general to stabilize hydroxyalkyl (meth)acrylate by adding polymerization inhibitor in its manufacturing process, storage or transportation. As the polymerization inhibitor, hitherto, various compounds have been used, including phenol compounds such as hydroquinone, methyl hydroquinone, tert-butyl hydroquinone, 2,6-di-tert-butyl parahydroquinone, 2,5-di-tert-butyl hydroquinone, 2,4-dimethyl-6-tert-butyl phenol, and hydroquinone monomethyl ether, or para-phenylene diamines such as N-isopropyl-N′-phenyl-para-phenylene diamine, N-(1,3-dimethyl butyl)-N′-phenyl-para-phenylene diamine, N-(1-methyl heptyl)-N′-phenyl-para-phenylene diamine, N,N′-diphenyl-para-phenylene diamine, and N,N′-di-2-naphthyl-para-phenylene diamine, or amines such as thiodiphenylamine.
However, as mentioned above, hydroxyalkyl (meth)acrylate is very likely to be polymerized. Usually, products of hydroxyalkyl (meth)acrylate contain impurities, including water, alkylene chlorohydrin, alkylene glycol di(meth)acrylate, dialkylene glycol mono(meth)acrylate, dialkylene glycol di(meth)acrylate, trialkylene glycol mono(meth)acrylate, trialkylene glycol di(meth)acrylate, (meth)acrylic acid dimer, hydroxyalkyl-&bgr;-acryloyloxy propionate, dialkylene glycol-&bgr;-acryloyloxy propionate, reaction materials such as (meth)acrylic acid and alkylene oxide, and others, in a range of several ppm to several percent, and they act to promote polymerization of hydroxyalkyl (meth)acrylate. Owing to these reasons, if the conventional polymerization inhibitors as listed above are used in stabilization of hydroxyalkyl (meth)acrylate, the polymerization inhibitory effects were not sufficient. It causes problems not only in the storage and transportation process, but also in the manufacturing process of hydroxyalkyl (meth)acrylate, in particular, and if polymerization takes place in the course of operation, pipings are clogged and the productivity is lowered, which leads to a tremendous economical loss.
SUMMARY OF THE INVENTION
A. Object of the Invention
Accordingly, an object of the present invention is to sufficiently stabilize the hydroxyalkyl (meth)acrylate in spite of its easily polymerizable property.
B. Disclosure of the Invention
The present inventors diligently studied to solve the above problems. As a result, the inventors have completed the present invention by finding that, by adding a specific ester compound and/or glycol compound to the phenol compound hitherto used as polymerization inhibitor, the stabilizing effect upon the easily polymerizable hydroxyalkyl (meth)acrylate is considerably enhanced as compared with conventional cases.
That is to say, a stabilized hydroxyalkyl (meth)acrylate, according to the present invention, contains a hydroxyalkyl saturated-carboxylate and/or alkylene glycol along with a phenol compound.
These and other objects and the advantages of the present invention will be more fully apparent from the following detailed disclosure.
DETAILED DESCRIPTION OF THE INVENTION
Stabilizing Method
The present invention is characterized by achieving the stabilization of the hydroxyalkyl (meth)acrylate by using the hydroxyalkyl saturated-carboxylate and/or alkylene glycol jointly with the phenol compound.
The phenol compound used in the present invention is a phenol compound conventionally and generally used as polymerization inhibitor, and preferable examples thereof include hydroquinone, methyl hydroquinone, tert-butyl hydroquinone, 2,6-di-tert-butyl parahydroquinone, 2,5-di-tert-butyl hydroquinone, 2,4-dimethyl-6-tert-butyl phenol, and hydroquinone monomethyl ether. These may be used either alone respectively or in combinations with each other.
The hydroxyalkyl saturated-carboxylate and/or alkylene glycol used together with the phenol compound in the present invention is a compound which characterizes the technical concept of the present invention. Examples of the hydroxyalkyl saturated-carboxylate preferably include hydroxyethyl acetate, hydroxyethyl propionate, hydroxyethyl isobutyrate, hydroxypropyl acetate, hydroxypropyl propionate, and hydroxypropyl isobutyrate. These may be used either alone respectively or in combinations with each other. As the alkylene glycol, preferably, ethylene glycol, propylene glycol and others may be used. These may also be used either alone respectively or in combinations with each other.
In the present invention, the amount of the phenol compound as used is preferably in the range of 0.001 to 0.5 wt % of hydroxyalkyl (meth)acrylate, and preferably 0.005 to 0.1 wt %. If less than 0.001 wt %, the polymerization inhibitory effect is not enough, or if more than 0.5 wt %, it is not economical.
In the present invention, the amount of the hydroxyalkyl saturated-carboxylate and/or alkylene glycol as used is preferably in the range of 0.0001 to 2 wt %, more preferably 0.001 to 2 wt %, and still more preferably 0.01 to 1 wt %, of hydroxyalkyl (meth)acrylate. If less than 0.0001 wt %, the polymerization inhibitory effect is not enough, or if more than 2 wt %, it is not economical.
In the present invention, the mixing rate of hydroxyalkyl saturated-carboxylate and/or alkylene glycol to phenol compound is not particularly limited, and each should be contained at the above rate in the hydroxyalkyl (meth)acrylate, and the blending rate by weight of the hydroxyalkyl saturated-carboxylate and/or alkylene glycol to the phenol compound is preferably in the range of 0.1 to 100 times, more preferably 1 to 80 times. If less than 0.1 times or more than 100 times, it is not preferred because the feature of the present invention, that is, the synergistic effect by combined use of hydroxyalkyl saturated-carboxylate and/or alkylene glycol with phenol compound is decreased.
In the present invention, the compound to be combined with the phenol compound is hydroxyalkyl saturated-carboxylate and/or alkylene glycol, and by either compound, the stabilizing effect of the present invention is sufficiently exhibited, and in particular the hydroxyalkyl saturated-carboxylate tends to have a higher stabilizing effect than the alkylene glycol.
In the present invention, the hydroxyalkyl saturated-carboxylate and/or alkylene glycol as well as the phenol compound is allowed to coexist with the hydroxyalkyl (meth)acrylate, but, if aromatic hydrocarbon and/or aliphatic hydrocarbon is also allowed to coexist with the hydroxyalkyl (meth)acrylate, the polymerization inhibitory effect upon hydroxyalkyl (meth)acrylate is enhanced. The aromatic hydrocarbon is not particularly limited, but is preferably at least one member selected from the group consisting of benzene, toluene, and xylene. The aliphatic hydrocarbon is not particularly limited, but is preferably at least one member selected from the group consisting of hexane, heptane, and octane. In the case where the aromatic hydrocarbon and/or aliphatic hydrocarbon is also allowed to coexist with the hydroxyalkyl (meth)acrylate, the amount of the aromatic hydrocarbon and/or aliphatic hydrocarbon as added is preferably in the range of 0.0001 to 1 wt %, more preferably 0.0001 to 0.1 wt %, of hydroxyalkyl (meth)acrylate. If less than 0.0001 wt %, the polymerization inhibitory effect is not enough, or if more than 1 wt %, it is not economical.
In the present invention, the method of adding phenol compound, hydroxyalkyl saturated-carboxylate and/or alkylene glycol, and, if necessary, aromatic hydrocarbon and/or aliphatic hydrocarbon, for stabilization of hydroxyalkyl (meth)acrylate is not particularly limited, but, for example, in the manufacturing process of hydroxyalkyl (meth)acrylate, they may be added together with the raw materials, or may be added in the distillation tower in the refining process. Or, by a method of adding saturated carboxylic acid corresponding to hydroxyalkyl saturated-carboxylate, for e
Ishida Tokumasa
Shingai Yasuhiro
Ueoka Masatoshi
Anthony Joseph D.
Haugen Law Firm PLLP
Nippon Shokubai Co. , Ltd.
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