Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Polymers from only ethylenic monomers or processes of...
Reexamination Certificate
2002-04-22
2004-09-21
Pezzuto, Helen L. (Department: 1713)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Polymers from only ethylenic monomers or processes of...
C526S317100, C526S320000, C526S333000
Reexamination Certificate
active
06794473
ABSTRACT:
BACKGROUND OF THE INVENTION
A. Technical Field
The present invention relates to an acrylic acid (salt) polymer, its production process, and an acrylic acid (salt) polymer composition comprising this acrylic acid (salt) polymer, wherein the acrylic acid (salt) polymer displays excellent performance, for example, as detergent builders, scale inhibitors, pigment dispersants, thickeners, and flocculants.
B. Background Art
Hitherto, it has been known that acrylic acid (salt) polymers are useful for various uses such as detergent builders, scale inhibitors, pigment dispersants, thickeners, and flocculants, and processes for obtaining these acrylic acid (salt) polymers have variously been proposed so far. For example, processes for obtaining low molecular acrylic acid (salt) polymers, which are fitted for uses such as detergent builders, scale inhibitors, and pigment dispersants, are proposed in JP-A-270605/1987, JP-A-086125/1993, and JP-A-268304/1992. On the other hand, processes for obtaining high molecular acrylic acid (salt) polymers, which are fitted for uses such as thickeners and flocculants, are proposed in JP-B-030426/1979, JP-B-031564/1982, and JP-B-036926/1982.
Desired for the uses such as detergent builders, scale inhibitors, and pigment dispersants are acrylic acid (salt) polymers that have low molecular weights and narrow molecular weight distributions and can display excellent dispersibility. On the other hand, desired for the uses such as thickeners and flocculants are acrylic acid (salt) polymers that have high molecular weights and high water solubilities. Also as to the prior arts as described in the above official gazettes, the improvement of the dispersibility and the solubility is attempted. However, there still remain the following problems: for example, effects of the improvement are not sufficient and are limited in respect to production facilities and procedures.
SUMMARY OF THE INVENTION
A. Object of the Invention
Accordingly, an object of the present invention is to provide: an acrylic acid (salt) polymer, which has a low molecular weight and a narrow molecular weight distribution and can display excellent dispersibility, or which has a high molecular weight and a high water solubility; a production process that enables easy production of this polymer; and an acrylic acid (salt) polymer composition comprising this polymer.
B. Disclosure of the Invention
The present inventors diligently studied to solve the above-mentioned problems. As a result, they have found out that the acrylic acid (salt) polymer, which has a low molecular weight and a narrow molecular weight distribution and can display excellent dispersibility, or which has a high molecular weight and a high water solubility, can be obtained by carrying out polymerization using an acrylic acid (salt) containing furfural in not smaller than a definite amount in the polymerization step and thereby making an aldehyde structure, as derived from the furfural, exist in the resultant polymer.
Acrylic acid as a raw material of the acrylic acid (salt) polymers is conventionally, for example, produced by gas phase oxidation of propylene or acrolein. As to such a process, however, it is known that the production step involves formation of by-products as impurities, such as aldehydes (e.g. furfural). Accordingly, the resultant product contains the impurities in a large amount besides the aimed acrylic acid. Therefore, usually, the impurities were removed by carrying out a purification treatment (for example, distillation) of the resultant product, and thereafter the resultant acrylic acid was provided to the polymerization reactions for obtaining the acrylic acid (salt) polymers (JP-B-038601/1982). Because it was thought that the aldehydes such as furfural contained in acrylic acid had a bad influence as impurities on the polymerization reactions for obtaining the acrylic acid (salt) polymers.
On the contrary to this conventional thought, the findings obtained by the present inventors are that better results are obtained by making the furfural exist in the raw acrylic acid (salt) or in the acrylic acid (salt) polymer rather than by removing the furfural.
The present invention has been completed on the basis of these findings.
That is to say, an acrylic acid (salt) polymer, according to the present invention, is an acrylic acid (salt) polymer of which not less than 1 weight % of the entirety is accounted for by an acrylic acid (salt) polymer having a terminal structure of a formula (1) below:
A production process for an acrylic acid (salt) polymer, according to the present invention, comprises the step of carrying out polymerization of a monomer component including an acrylic acid (salt), with the production process being characterized in that an acrylic acid (salt) having a furfural content of 200 to 400 weight ppm is used as at least a portion of the acrylic acid (salt) in an amount of not smaller than 10 weight % of the entire monomer component.
Then, acrylic acid (salt) polymer composition, according to the present invention, comprises an acrylic acid (salt) polymer wherein a structural unit derived from an acrylic acid (salt) accounts for not less than 10 weight % of the acrylic acid (salt) polymer, with the acrylic acid (salt) polymer composition being characterized by further comprising a compound, as derived from furfural, in an amount of 100 to 50,000 weight ppm.
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, modes for carrying out the present invention are explained in detail.
The acrylic acid (salt) polymer, according to the present invention, is an acrylic acid (salt) polymer of which not less than 1 weight % of the entirety is accounted for by an acrylic acid (salt) polymer having a terminal structure of the aforementioned formula (1).
The aldehyde structure of the aforementioned formula (1) is derived from furfural, and the present invention polymer is easily obtained by the below-mentioned production process.
In the case where the acrylic acid (salt) polymer having the terminal structure of the aforementioned formula (1) accounts for less than 1 weight % of the entirety, the polymer cannot display excellent dispersibility. Incidentally, as to the present invention acrylic acid (salt) polymer, it is enough that not less than 1 weight % of its entirety is accounted for by the polymer having the aforementioned specific terminal aldehyde structure, and, if this range is satisfied, the other terminal of this polymer is not especially limited.
The present invention acrylic acid (salt) polymer mainly comprises a structural unit derived from the acrylic acid (salt), but may further comprise structural units derived from other copolymerizable monomers below, if necessary. In this case, the amount of the structural unit derived from the acrylic acid (salt) is favorably at least 10 weight %.
In the present invention, the carboxyl group portion of the acrylic acid (salt) polymer may be in any form of an acid form, a partial salt form, a perfect salt form, and their mixture form. Examples of the salt include: salts of alkaline metals, such as sodium and potassium; salts of alkaline earth metals, such as calcium and magnesium; ammonium salts; and salts of organic amines, such as monoethanolamine and triethanolamine. Among these, the salts of alkaline metals such as sodium and potassium are especially favorable, and the sodium salts are particularly favorable. Incidentally, these salts may be used either alone respectively or in combinations with each other.
In favorable modes of the acrylic acid (salt) polymer according to the present invention, the dispersion degree thereof is not more than 3.0. In the case where the dispersion degree is more than 3.0, the clay dispersibility tends to decrease, for example, when the polymer is used as a detergent builder. Incidentally, the dispersion degree is a value calculated by weight-average molecular weight
umber-average molecular w
Hirata Tsuyoshi
Shioji Shorbu
Yamaguchi Shigeru
Nippon Shokubai Co. , Ltd.
Pezzuto Helen L.
Roylance Abrams Berdo & Goodman L.L.P.
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