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
2001-02-22
2003-06-10
Zalukaeva, Tatyana (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...
C526S240000, C526S317100, C528S232000, C528S250000
Reexamination Certificate
active
06576714
ABSTRACT:
BACKGROUND OF THE INVENTION
A. Technical Field
The present invention relates to a production process for a glyoxylic acid (salt)-based polymer. More specifically, the present invention relates to a production process for a terminal-end-stabilized glyoxylic acid (salt)-based polymer.
B. Background Art
A glyoxylic acid (salt)-based polymer has many carboxyl groups in its molecule and therefore displays an excellent function of binding (chelating) the calcium ion or magnesium ion present in water and then dispersing clay and dirt, and further, the glyoxylic acid (salt)-based polymer contains no phosphorus causing environmental pollution such as eutrophication of rivers etc. and is therefore hitherto favorably used as a detergent builder.
As to production processes for the glyoxylic acid (salt)-based polymer, for example, JP-A-052196/1979 and JP-A-050316/1987 (corresponding to U.S. Pat. No. 4,600,750) disclose: a process which comprises the step of polymerizing a glyoxylic acid ester by using a solvent such as an alkanenitrile, a halogenated hydrocarbon, dimethyl sulfoxide, or acetone in order to obtain a glyoxylic acid-based polymer; and a process which comprises the step of further saponifying (hydrolyzing) the glyoxylic acid-based polymer in order to obtain a glyoxylic acid salt-based polymer.
In addition, the glyoxylic acid (salt)-based polymer has unstable terminal end portions because the main chain of this polymer has an acetal structure. Accordingly, in the case where, in order to isolate the glyoxylic acid (salt)-based polymer, a reaction liquid containing the polymer is for example heated to remove a solvent etc. therefrom, the main chain is cut off from the terminal end portions of the polymer, so that the polymer decomposes (depolymerizes). In other words, it is difficult to isolate or purify the glyoxylic acid (salt)-based polymer stably in a high yield. Therefore, a process is disclosed which process comprises the step of stabilizing the terminal end portions of the glyoxylic acid (salt)-based polymer by treating it with a terminal end stabilizer. For example, U.S. Pat. No. 4,144,226, U.S. Pat. No. 4,204,052, U.S. Pat. No. 4,225,685, and U.S. Pat. No. 4,226,960 disclose a process which comprises the step of polymerizing a glyoxylic acid ester by using a solvent such as an alkanenitrile, a halogenated hydrocarbon, dimethyl sulfoxide, or acetone, in which process a terminal end stabilizer is added during or after the polymerization.
However, the above conventional production processes have problems in respect to production efficiency and cost because the polymerization solvent must be recovered or removed after the end of the polymerization (before the start of the hydrolysis) or after the end of the hydrolysis. In addition, in the case where the amount of the polymerization solvent as used is decreased in order to reduce the recovery or removal amount of the polymerization solvent, there are problems in that the viscosity of the polymerization liquid rises to deteriorate the agitation efficiency. Furthermore, an organic solvent such as an alkanenitrile, a halogenated hydrocarbon, dimethyl sulfoxide, or acetone is hitherto used as the polymerization solvent, therefore there might occur problems in respect to safety and environmental pollution resistance if a part of the above solvent remains after the step of recovering or removing it.
SUMMARY OF THE INVENTION
A. Object of the Invention
An object of the present invention is to provide a production process for a terminal-end-stabilized glyoxylic acid (salt)-based polymer, which process enables to reduce the amount of the polymerization solvent, as recovered or removed after the end of the polymerization (before the start of the hydrolysis) or after the end of the hydrolysis, without lowering the production efficiency.
B. Disclosure of the Invention
The present inventors diligently studied to solve the above problems. As a result, they have hit on ideas that: (1) the terminal end stabilizer, which is conventionally added during or after the polymerization in order to stabilize the terminal ends of the glyoxylic acid (salt)-based polymer, can be utilized as a reaction medium of the polymerization; and (2) if the polymerization reaction of a monomer component including a glyoxylic acid ester and the terminal-end-stabilizing reaction can be run by their respective catalysts having different functions, then the terminal end stabilizer serves as a reaction medium without reacting during the polymerization reaction, and can be made to react by adding a terminal-end-stabilizing catalyst into the system after the polymerization. Then, the inventors have completed the present invention by finding that the above problems can be solved by the above ideas.
That is to say, a production process for a terminal-end-stabilized glyoxylic acid (salt)-based polymer, according to the present invention, comprises the step of polymerizing a monomer component including a glyoxylic acid ester in order to produce the terminal-end-stabilized glyoxylic acid (salt)-based polymer, wherein a terminal end stabilizer is used as a reaction medium of the polymerization. Preferably, if the polymerization of the monomer component including the glyoxylic acid ester is carried out as an anionic polymerization, and if a cationically polymerizable one is used as the terminal end stabilizer, then the terminal end stabilizer serves as a reaction medium without reacting until adding an acid catalyst into the polymerization system, and the addition of the acid catalyst then causes the terminal end stabilizer to react with the terminal ends of the glyoxylic acid (salt)-based polymer (as obtained by the anionic polymerization of the monomer component including the glyoxylic acid ester) in order to stabilize the terminal ends of this polymer.
The adoption of this constitution enables to simplify the polymerization solvent recovery or removal step without lowering the production efficiency and to more easily produce the glyoxylic acid (salt)-based polymer.
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
Hereinafter, the production process for the terminal-end-stabilized glyoxylic acid (salt)-based polymer, according to the present invention, is explained in detail.
Monomer Component Including Glyoxylic Acid Ester
The monomer component including the glyoxylic acid ester, as used in the present invention production process, is explained at first.
The glyoxylic acid ester, as included in the above monomer component, is represented by general formula (1) below:
OHC—CO—OR
1
(1)
where R
1
represents an alkyl group having 1 to 18 carbon atoms, an alkenyl group having 2 to 18 carbon atoms, or an aromatic hydrocarbon group.
For decreasing the steric hindrance during the polymerization, it is more favorable that the above glyoxylic acid ester has an alkyl group having 1 to 4 carbon atom as the substituent which is represented by R
1
in the above formula. Specific examples of the glyoxylic acid ester include methyl glyoxylate, ethyl glyoxylate, n-propyl glyoxylate, iso-propyl glyoxylate, n-butyl glyoxylate, isobutyl glyoxylate, sec-butyl glyoxylate, and t-butyl glyoxylate. These glyoxylic acid esters can be used either alone respectively or in combinations with each other. Of the above glyoxylic acid esters, methyl glyoxylate and ethyl glyoxylate are more favorable, and methyl glyoxylate is still more favorable.
The production process for the glyoxylic acid ester is not especially limited. The glyoxylic acid ester can easily be produced, for example, by dehydration of a hemiacetal ester of glyoxylic acid by use of phosphorus pentoxide or sulfuric acid, wherein the hemiacetal ester is obtained by a reaction of glyoxylic acid hydrate and an alcohol.
Incidentally, the glyoxylic acid ester might gradually polymerize even during its storage (preservation) according to storage conditions. Therefore, it is desirable to purify the glyoxylic acid es
Fujii Yoshikazu
Kanzaki Akihiko
Nakamura Jun-ichi
Saeki Takuya
Yamaguchi Shigeru
Haugen Law Firm PLLP
Nippon Shokubai Co. , Ltd.
Zalukaeva Tatyana
LandOfFree
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