Process for preparing vinylpyrrolidone polymer

Details Process for preparing vinylpyrrolidone polymer Process for preparing vinylpyrrolidone polymer

2001-08-03

2002-10-15

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...

C526S258000, C526S260000, C526S222000, C526S227000, C526S230000, C526S236000

Reexamination Certificate

active

06465592

ABSTRACT:

TECHNICAL FIELD
The present invention relates to a process for preparing a vinylpyrrolidone polymer, wherein a specific redox initiator is employed. Particularly, the present invention relates to a process for preparing a vinylpyrrolidone polymer which is not colored, does not give off a bad smell, and contains extremely little impurities (for example, remaining monomers or by-products).
BACKGROUND ART
One of the conventional processes for polymerization of vinylpyrrolidone is a process using aqueous hydrogen peroxide as an initiator (DE-B922378). However, when the process is employed, pH control is required during the polymerization. The process also has problems that 2-pyrrolidone is produced as a by-product in proportion to the amount of hydrogen peroxide (Polymer Journal, vol. 17, No. 1, pp143-152 (1985)), or that products are colored. The above process is effective for preparing a vinylpyrrolidone polymer having a low molecular weight, but because products are colored, another process has been expected especially for a cosmetic use.
The process using azo compounds as an initiator is disclosed (Japanese Unexamined Patent Publication No. 38403/1989). Even by the process, impurities derived from the initiator remain in products, and therefore the process is not useful for a cosmetic use.
The process using a redox initiator consisting of a peroxide and Rongalit is disclosed (Japanese Unexamined Patent Publication No. 215302/1984). It is predicted in the process that a bad smell will be caused because aldehyde remains as an impurity in products. Therefore, the process seems inappropriate for a cosmetic use.
The process using di-tert-butyl peroxide singly as an initiator is also disclosed (Japanese Examined Patent Publication No. 19174/1996). However, polymerization requires to be carried out at 100° C. or more under a pressurized condition because the decomposition temperature of di-tert-butyl peroxidede is high.
DISCLOSURE OF THE INVENTION
It is an object of the present invention to provide a vinylpyrrolidone polymer which is little colored, gives off a bad smell little, and contains extremely little impurities.
The present invention relates to a process for preparing a vinylpyrrolidone polymer, wherein a water-soluble organic peroxide and a sulfite are added to a vinylpyrrolidone aqueous solution to polymerize vinylpyrrolidone, and to obtain a vinylpyrrolide polymer.
The present invention relates to the above-mentioned process for preparing a vinylpyrrolidone polymer, wherein a K value of the resulting vinylpyrrolidone polymer evaluated according to Fikentscher method is 10 to 120.
The present invention relates to each of the above-mentioned processes for preparing a vinylpyrrolidone polymer, wherein the water-soluble organic peroxide is added in an amount of 0.005 to 5% by weight and the sulfite is added in an amount of 0.005 to 10% by weight based on the vinylpyrrolidone.
The present invention relates to each of the above-mentioned processes for preparing a vinylpyrrolidone polymer, wherein the mole ratio of the water-soluble organic peroxide and the sulfite is 1:0.5 to 1:20.
The present invention relates to each of the above-mentioned processes for preparing a vinylpyrrolidone polymer, wherein the water-soluble organic peroxide and the sulfite are added to the reaction solution in installments for the polymerization.
The present invention relates to each of the above-mentioned processes for preparing a vinylpyrrolidone polymer, wherein the amount of the sulfite added initially is determined so that the mole ratio of the vinylpyrrolidone and the amount of the sulfite added initially is 1:0.0004 to 1:0.1.
The present invention relates to each of the above-mentioned processes for preparing a vinylpyrrolidone polymer, wherein the polymerization temperature of vinylpyrrolidone is 10 to 90° C.
The present invention relates to each of the above-mentioned processes for preparing a vinylpyrrolidone polymer, wherein the sulfite is ammonium sulfite.
The present invention relates to each of the above-mentioned processes for preparing a vinylpyrrolidone polymer, wherein the water-soluble organic peroxide is a hydroperoxide.
The present invention relates to each of the above-mentioned processes for preparing a vinylpyrrolidone polymer, wherein the water-soluble organic peroxide is tert-butyl hydroperoxide.
The present invention relates to each of the above-mentioned processes for preparing a vinylpyrrolidone polymer, wherein at most 10 ppm of vinylpyrrolidone is contained in the resulting vinylpyrrolidone polymer.
The present invention relates to a vinylpyrrolidone polymer containing a little amounts of vinylpyrrolidone, which is obtained by adding a water-soluble organic peroxide and a sulfite to a vinylpyrrolidone aqueous solution to polymerize vinylpyrrolidone.
The present invention relates to the above-mentioned vinylpyrrolidone polymer which contains at most 10 ppm of vinylpyrrolidone based on the vinylpyrrolidone polymer.
The present invention relates to a vinylpyrrolidone polymer, which has a K value evaluated according to Fikentscher method of 10 to 40, and Hazen No. (APHA) value in a 10% aqueous solution according to JIS K3331 of at most 10, and which contains at most 10 ppm of remaining vinylpyrrolidone based on the vinylpyrrolidone polymer.
BEST MODE FOR CARRYING OUT THE INVENTION
In the process for preparing a vinylpyrrolidone polymer of the present invention, a vinylpyrrolidone polymer is prepared by adding a water-soluble organic peroxide and a sulfite as a redox initiator to a vinylpyrrolidone (hereinafter referred to as “VP”) aqueous solution to initiate the polymerization.
Vinylpyrrolidone (VP) ordinarily means N-vinyl-2-pyrrolidone. A vinylpyrrolidone polymer implies a VP homopolymer and a copolymer consisting of VP and other monomers (the copolymer contains preferably at least 20% by weight, more preferably at least 30% by weight of VP units).
As other monomers, for example, acrylic acid, methacrylic acid, an alkylester of acrylic acid (for example, methyl acrylate and ethyl acrylate), an alkylester of methacrylic acid (for example, methyl methacrylate and ethyl methacrylate), an aminoalkylester of acrylic acid (for example, diethylaminoethyl acrylate), an aminoalkylester of methacrylic acid, a monoester of acrylic acid and a glycol, a monoester of methacrylic acid and a glycol (for example, hydroxyethyl methacrylate), an alkaline metal salt of acrylic acid, an alkaline metal salt of methacrylic acid, ammonium salt of acrylic acid, ammonium salt of methacrylic acid, a quaternary ammonium derivative of an aminoalkylester of acrylic acid, a quaternary ammonium derivative of an aminoalkylester of methacrylic acid, a quaternary ammonium compound of diethylaminoethylacrylate and methyl sulfate, vinyl methyl ether, vinyl ethyl ether, an alkaline metal salt of vinyl sulfonic acid, ammonium salt of vinyl sulfonic acid, styrene sulfonic acid, a styrene sulfonate, an allylsulfonic acid, an allyl sulfonate, methallylsulfonic acid, methallyl sulfonate, vinyl acetate, vinyl stearate, N-vinylimidazol, N-vinylacetamide, N-vinylformamide, N-vinylcaprolactam, N-vinylcarbazole, acrylamide, methacrylamide, N-alkylacrylamide, N-methylolacrylamide, N,N-methylenebisacrylamide, a glycol diacrylate, a glycol dimethacrylate, divinylbenzene, a glycol diallylether, and the like are employed.
Polymerization of VP or copolymerization of VP and other monomers can be carried out according to a solution polymerization in an aqueous solvent. For example, the polymerization can be carried out by adding an aqueous solution of a water-soluble organic peroxide and an aqueous solution of a sulfite to a VP aqueous solution.
As the VP aqueous solution, for example, an aqueous solution having a VP concentration of 10 to 60%, preferably 20 to 50% by weight can be used. When an aqueous solution containing VP and other monomers is employed as the VP aqueous solution, the aqueous solution is 10 to 60% by weight, preferably 20 to 50% by weight in total concentration of VP and other monomers. When the concentrat

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