Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Polymers from only ethylenic monomers or processes of...
Reexamination Certificate
1999-06-08
2001-10-02
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...
C524S556000, C524S832000
Reexamination Certificate
active
06297336
ABSTRACT:
BACKGROUND OF THE INVENTION
A. Technical Field
The present invention relates to a detergent builder, a production process therefor, and a poly(meth)acrylic acid (or salt) polymer and a use thereof.
B. Background Art
The poly(meth)acrylic acid (or salt) polymer is a useful polymer and, for example, used for detergent builders, scale inhibitors, and inorganic pigment dispersants. A typical production process therefor comprises the step of polymerizing a monomer component including a major proportion of (meth)acrylic acid (or salt) in the presence of a chain transfer agent and a polymerization initiator in an aqueous medium.
U.S. Pat. No. 2,789,099 discloses a production process for a polyacrylic acid polymer comprising the step of carrying out a polymerization reaction of an aqueous solution containing acrylic acid, a peroxide (as a polymerization initiator), and a specific copper compound and a specific alkaline-metal hypophosphite (as chain transfer agents), and sets forth an example of preferred embodiments (working example) in which raw materials are charged all at once and then heated to carry out polymerization, and further, another example in which raw materials other than the peroxide are initially charged and heated, and thereafter, the peroxide is added, while the polymerization is carried out. This prior USP exemplifies fiber-sizing agents, soil stabilizers, adhesives, and emulsifiers as uses of the polyacrylic acid polymer.
JP-A-011092/1980 discloses the use of a specific poly(meth)acrylic acid polymer (telomer compound) as an aqueous treating agent, and sets forth an example of preferred embodiments (working example) in which the telomer compound is produced by a process comprising the step of dropping an aqueous sodium persulfate solution and acrylic acid to an aqueous sodium hypophosphite solution and heating the resultant mixture.
JP-A-293599/1986 relates to a heat-resistant scale inhibitor comprising a poly(meth)acrylic acid polymer, and sets forth an example of preferred embodiments (working example) in which water is charged into a reactor and then heated, and thereafter, an aqueous acrylic acid solution, an aqueous hypophosphorous acid (or salt) solution, and an aqueous polymerization initiator solution are dropped thereto, while the polymerization is carried out, and further, another example in which a hypophosphorous acid solution is charged into a reactor and then heated, and thereafter, acrylic acid (aqueous solution) and a polymerization initiator (aqueous solution) are dropped thereto, while the polymerization is carried out.
The gelation resistance and the chelating ability are exemplified as main properties as demanded when the poly(meth)acrylic acid (or salt) polymer is, for example, used for detergent builders, inorganic pigment dispersants, and scale inhibitors. The gelation resistance is an index showing the unlikeliness of the occurrence of a phenomenon in which polycharged metal ions, such as calcium ion, present in the system, precipitates and gels due to contact with the poly(meth)acrylic acid (or salt) polymer, and it is generally assumed that the higher the molecular weight is, the lower the gelation resistance is. On the other hand, the chelating ability is an index showing the ability to chelate the polycharged metal ions, such as calcium ion, present in the system, and it is generally assumed that the higher the molecular weight is, the better the chelating ability is. Thus, there is a trade-off relation between the gelation resistance and the chelating ability with regard to the molecular weight, so it is difficult to obtain good results with regard to both the gelation resistance and the chelating ability.
Furthermore, any of the poly(meth)acrylic acids (or salts), as obtained by the processes as disclosed in the above prior art documents, has so broad a molecular weight distribution that high-molecular and low-molecular components, greatly deviating from the average molecular weight, are present, and these components are the causes to lower the gelation resistance and the chelating ability respectively.
SUMMARY OF THE INVENTION
A. Objects of the Invention
An object of the present invention is to provide a detergent builder and a production process therefor, which detergent builder comprises a poly(meth)acrylic acid (or salt) polymer that has a narrow molecular weight distribution and is excellent both in the gelation resistance and the chelating ability. In addition, another object of the present invention is to provide a poly(meth)acrylic acid (or salt) polymer which has a narrow molecular weight distribution, and is excellent both in the gelation resistance and the chelating ability, and is favorably used not only for detergent builders, but also for inorganic pigment dispersants and scale inhibitors.
B. Disclosure of the Invention
To solve the above problems, the present invention provides the following:
(1) A detergent builder, comprising a poly(meth)acrylic acid (or salt) polymer which gives a product (A×B) of 18,000 or more from the gelation resistance (A) and the chelating ability (B).
(2) A production process for a detergent builder, comprising the step of polymerizing a monomer component including a major proportion of (meth)acrylic acid (or salt) in the presence of a chain transfer agent and a polymerization initiator in an aqueous medium, thus obtaining a detergent builder including the resultant poly(meth)acrylic acid (or salt) polymer;
with the process being characterized in that:
the ratio by weight of (total amount of monomer component, chain transfer agent, and polymerization initiator) to (total amount of aqueous medium) is in the range of 46:54~66:34;
10 weight % or more of the total amount of the aqueous medium and 0~50 weight % of the total amount of the chain transfer agent are beforehand charged into a reactor; and
the polymerization is carried out within the reaction temperature range of 50-120° C. while 70 weight % or more of the total amount of the monomer component, 50 weight % or more of the total amount of the chain transfer agent, and 80 weight % or more of the total amount of the polymerization initiator are gradually supplied to the reaction system having a temperature of 50~120° C.
(3) A poly(meth)acrylic acid (or salt) polymer, obtained by a process including the step of polymerizing a monomer component including a major proportion of (meth)acrylic acid (or salt) in the presence of a chain transfer agent and a polymerization initiator in an aqueous medium;
with the polymer being characterized in that:
the ratio by weight of (total amount of monomer component, chain transfer agent, and polymerization initiator) to (total amount of aqueous medium) is in the range of 46:54~66:34;
10 weight % or more of the total amount of the aqueous medium and 1~50 weight % of the total amount of the chain transfer agent are beforehand charged into a reactor; and
the polymerization is carried out within the reaction temperature range of 50~120° C. while 70 weight % or more of the total amount of the monomer component, 50 weight % or more of the total amount of the chain transfer agent, and 80 weight % or more of the total amount of the polymerization initiator are gradually supplied to the reaction system having a temperature of 50~120° C.
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 inventors studied every production condition for the purpose of obtaining a poly(meth)acrylic acid (or salt) polymer that has a narrower molecular weight distribution than conventional ones. As a result, they found that: at first, the way to add the raw materials (monomer component, chain transfer agent, polymerization initiator, and aqueous medium), as used for the polymerization, is exemplified by a way in which the raw materials are beforehand charged into the reactor, and by a way in which the raw materials are gradually supplied after the reaction system has been heated, and among the raw mat
Maeda Yoshihiro
Shioji Shorbu
Yamaguchi Shigeru
Nippon Shokubai Co. , Ltd.
Pezzuto Helen L.
Roylance Abrams Berdo & Goodman L.L.P.
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