Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Treating polymer containing material or treating a solid...
Reexamination Certificate
2001-09-26
2003-03-18
Boykin, Terressa M. (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Treating polymer containing material or treating a solid...
Reexamination Certificate
active
06534625
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Technical Field
The present invention relates to a process for producing a hydroxyalkyl (meth)acrylate, which comprises the step of carrying out a reaction between (meth)acrylic acid and an alkylene oxide.
2. Background Art
As to processes for producing a hydroxyalkyl (meth)acrylate which comprise the step of carrying out a reaction between (meth)acrylic acid and an alkylene oxide, it is known that the alkylene oxide is supplied to a reactor in a molar quantity excessive to (meth)acrylic acid so that the formation of by-products, such as alkylene glycol di(meth)acrylate (which might hereinafter be referred to as diester) and dialkylene glycol mono(meth)acrylate, can be inhibited, and so that the conversion of (meth)acrylic acid can be enhanced as much as possible (e.g. JP-B-013019/1966, JP-B-018890/1968). In this case, the unreacted residue of the alkylene oxide is present in the resultant reaction liquid at the end of the reaction, Therefore, after being separated from the reaction liquid, this residue needs to be disposed of, or recovered and recycled.
However, in the case where the alkylene oxide, as separated from the reaction liquid by such as stripping, is condensed by cooling for the above recovery and recycling, the cooling needs so great a deal of energy as to be economically disadvantageous.
In addition, JP-A-330320/1998 discloses that the unreacted residue of the alkylene oxide can be effectively utilized by causing it to be absorbed into raw (meth)acrylic acid and then recycling the resultant alkylene-oxide-containing (meth)acrylic acid to the reaction. However, the amount of (meth)acrylic acid as the absorbing solvent is limited by the molar ratio of the reaction, therefore this prior art cannot be said to be on a sufficiently satisfactory level in respect to the recovery efficiency.
SUMMARY OF THE INVENTION
A. Object of the Invention
An object of the present invention is to provide a process for producing a hydroxyalkyl (meth)acrylate which comprises the step of carrying out a reaction between (meth)acrylic acid and an alkylene oxide, wherein the process provides enablement for economically and efficiently recovering and recycling the unreacted residue of the alkylene oxide.
B. Disclosure of the Invention
The present inventors diligently studied to solve the above problems. As a result, the inventors directed their attention to stripping the unreacted residue of the alkylene oxide from the reaction liquid to separate therefrom the unreacted residue of the alkylene oxide, and then using water as an absorbing solvent to cause it to absorb the separated unreacted residue of the alkylene oxide. Water has advantages in that: it has a lower solidifying point than (meth)acrylic acid, therefore its absorption temperature can be set to be so low as to enhance the absorption efficiency of the unreacted residue of the alkylene oxide. In addition, water can further exhibit the economical advantage of being inexpensive. And the inventors have completed the present invention by further leading to an idea that the absorbing liquid resultant from the above absorption of the unreacted residue of the alkylene oxide is an aqueous alkylene oxide solution and therefore can be recycled as a raw material for production of an alkylene glycol.
That is to say, a process for producing a hydroxyalkyl (meth)acrylate, according to the present invention, comprises the steps of: carrying out a reaction between (meth)acrylic acid and an alkylene oxide; stripping the unreacted residue of the alkylene oxide from the resultant reaction liquid, and causing a solvent to absorb the stripped alkylene oxide; wherein:
water is used as the absorbing solvent; and an absorbing liquid resultant from the absorption of the unreacted residue of the alkylene oxide is used for production of an alkylene glycol.
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
The present invention is explained in detail below.
First, the process for producing a hydroxyalkyl (meth)acrylate to which the characteristic production process according to the present invention is favorably applicable is roughly explained as follows.
First, an addition reaction between (meth)acrylic acid and the alkylene oxide is carried out in the presence of a catalyst. The conversion in this addition reaction is often less than 100%, therefore generally such as the unreacted residue of the (meth)acrylic acid or alkylene oxide is present in the resultant reaction liquid at the end of the reaction. Thus, the above reaction liquid is led to the step to remove such as these unreacted residues of raw materials from the reaction liquid, and then purified by such as distillation as the subsequent final step, with the result that the aimed hydroxyalkyl (meth)acrylate is obtained.
When the present invention is carried out, the amount of raw materials as charged for the above reaction between (meth)acrylic acid and the alkylene oxide is such that the alkylene oxide is favorably in the range of 1.0 to 5.0 mols, more favorably in the range of 1.0 to 3.0 mols, still more favorably in the range of 1.0 to 2.0 mols, per 1 mol of (meth)acrylic acid. In the case where the amount of the alkylene oxide as charged is smaller than 1.0 mol, there are disadvantages in that the conversion of (meth)acrylic acid is lowered to increase the by-products. In addition as the amount of the alkylene oxide as charged is increased from 1 mol, the formation of the by-products can be inhibited more and more. However, in the case where the amount of the alkylene oxide as charged is larger than 5 mols, there are economical disadvantages.
When carrying out the present invention, the catalyst used for the above reaction between (meth)acrylic acid and the alkylene oxide is not especially limited, but, for example, conventional homogeneous or heterogeneous catalysts for addition reactions can be used.
In addition, conventional polymerization inhibitors are usable as stabilizers for the reaction liquid. Examples thereof include: phenol compounds such as hydroquinone, methylhydroquinone, tert-butylhydroquinone, 2,6-di-tert-butylhydroquinone, 2,5-di-tert-butylhydroquinone, 2,4-dimethyl-6-tert-butylphenol, hydroquinone monomethyl ether, cresol, and tert-butylcatechol; paraphenylenediamines such as N-isopropyl-N′-phenyl-para-phenylenediamine, N-(1,3-dimethylbutyl)-N′-phenyl-para-phenylenediamine, N-(1-methylheptyl)-N′-phenyl-para-phenylenediamine, N,N′-diphenyl-para-phenylenediamine, and N,N′-di-2-naphthyl-para-phenylenediamine; amine compounds such as thiodiphenylamine and phenothiazine; copper dialkyldithiocarbamates such as copper dibutyldithiocarbamate, copper dipropyldithiocarbamate, copper diethyldithiocarbamate, and copper dimethyldithiocarbamate; copper diaryldithiocarbamates such as copper diphenyldithiocarbamate; nitroso compounds such as nitrosophenol, N-nitrosodiphenylamine, isoamyl nitrite, N-nitroso-cyclohexylhydroxylamine, N-nitroso-N-phenyl-N-hydroxylamine, and their salts; N-oxyl compounds such as 2,2,4,4-tetramethylazetidine-1-oxyl, 2,2-dimethyl-4,4-dipropylazetidine-1-oxyl, 2,2,5,5-tetramethylpyrrolidine-1-oxyl, 2,2,5,5-tetramethyl-3-oxopyrrolidine-1-oxyl, 2,2,6,6-tetramethylpiperidine-1-oxyl, 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl, 6-aza-7,7-dimethyl-spiro(4,5)decane-6-oxyl, 2,2,6,6-tetramethyl-4-acetoxypiperidine-1-oxyl, 2,2,6,6-tetramethyl-4-benzoyloxypiperidine-1-oxyl, and 4,4′,4″-tris(2,2,6,6-tetramethylpiperidine-1-oxyl) phosphite; tetraalkylthiuram disulfides such as tetrabutylthiuram disulfide, tetrapropylthiuram disulfide, tetraethylthiuram disulfide, and tetramethylthiuram disulfide; and Methylene Blue. These polymerization inhibitors may be used either alone respectively or in combinations with each other. The amount of the polymerization inhibitor as added is in the range of favorably 0.0001 to 1 weight %, more favorably 0.001 to 0.5 weight %, of (meth)acrylic acid.
I
Ishida Tokumasa
Matsumoto Hajime
Yoneda Yukihiro
Boykin Terressa M.
Haugen Law Firm PLLP
Nippon Shokubai Co. Ltd
LandOfFree
Process for producing hydroxyalkyl (meth)acrylate does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Process for producing hydroxyalkyl (meth)acrylate, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Process for producing hydroxyalkyl (meth)acrylate will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3034003