Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Polymers from only ethylenic monomers or processes of...
Reexamination Certificate
2001-08-24
2002-11-26
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...
C526S223000, C526S230000, C525S328600, C525S383000
Reexamination Certificate
active
06486281
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a process for preparing a vinylpyrrolidone polymer, in particular, a process for preparing a high purity vinylpyrrolidone polymer which is soluble in an organic solvent such as isopropanol.
BACKGROUND ART
Concerning a process for preparing vinylpyrrolidone polymer, an initiator such as hydrogen peroxide, an azo compound or a redox initiator consisting of a peroxide and Rongalit is used conventionally. If one of these initiators is used, however, the resulting vinylpyrrolidone polymer is not useful for a cosmetic use because a by-product like 2-pyrrolidone or a by-product derived from the initiator is produced in a large amount.
Therefore, Applicant proposes a process for preparing a vinylpyrrolidone polymer by using a redox initiator consisting of an organic peroxide and a sulfite. Though a by-product like 2-pyrrolidone can be decreased in the process, the resulting vinylpyrrolidone polymer is insoluble in an organic solvent because sulfate ion and unreacted sulfite ion which are by-products remain in it.
DISCLOSURE OF THE INVENTION
It is an object of the present invention to provide a high purity vinylpyrrolidone polymer which has a decreased amount of a by-product derived from an initiator and is soluble in an organic solvent to be transparent.
Therefore, the present invention relates to a process for preparing a high purity vinylpyrrolidone polymer, which is characterized in polymerizing vinylpyrrolidone by using a redox initiator comprising an organic peroxide and a sulfite, and thereafter contacting the product with an anion exchange resin.
The present invention relates to the above-mentioned process for preparing a high purity vinylpyrrolidone polymer, wherein the sulfite is ammonium sulfite.
The present invention relates to the above-mentioned process for preparing a high purity vinylpyrrolidone polymer, wherein the organic peroxide is hydroperoxide.
The present invention relates to each of the above-mentioned processes for preparing a high purity vinylpyrrolidone polymer, wherein the organic peroxide is tert-butyl hydroperoxide.
The present invention relates to a high purity vinylpyrrolidone polymer containing a small amount of sulfate ion and sulfite ion, which is obtained by polymerizing vinylpyrrolidone using a redox initiator which contains an organic peroxide and a sulfite, and thereafter contacting the product with an anion exchange resin.
The present invention relates to the above-mentioned high purity vinylpyrrolidone polymer which contains at most 10 ppm of sulfate ion and at most 20 ppm of sulfite ion, based on the vinylpyrrolidone polymer.
BEST MODE FOR CARRYING OUT THE INVENTION
The process for preparing a high purity vinylpyrrolidone polymer of the present invention comprises polymerizing vinylpyrrolidone (hereinafter referred to as “VP”) by using a redox initiator which contains an organic peroxide and a sulfite, and purifying by adding an anion (basic ion) exchange resin to the resulting vinylpyrrolidone polymer aqueous solution and contacting the product with the anion (basic ion) exchange resin to remove sulfate ion and sulfite ion. 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-vinylcarbazol, acrylamide, methacrylamide, N-alkylacrylamide, N-methylolacrylamide, N, N-methylenebisacrylamide, a glycol diacrylate, a glycol dimethacrylate, divinylbenzene, a glycol diallylether, or 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 or in a mixed solvent consisting of an aqueous solvent and an organic solvent. For example, VP can be polymerized by adding an organic peroxide aqueous solution and a sulfite aqueous solution to a VP aqueous solution.
As the VP aqueous solution, for example, an aqueous solution having a VP concentration of 10 to 60% by weight, 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 concentration of the VP aqueous solution is low, a low productivity and high cost tend to be caused. When the concentration of the VP solution is high, a trouble in the reaction tends to be caused because viscosity becomes high with passage of time during polymerization and stirring becomes difficult.
As the organic peroxide, for example, any hydroperoxide such as tert-hexyl hydroperoxide, p-menthane hydroperoxide, cumene hydroperoxide and tert-butyl hydroperoxide, and any peroxide such as benzoylperoxide, laurylperoxide and stearylperoxide can be used. Hydroperoxide is preferable among them from the fact that a by-product derived from the initiator is decreased. tert-Butyl hydroperoxide is preferable in particular because in case of employing tert-butyl hydroperoxide as an initiator by-products such as tert-butanol can be removed easily by heating, or by decompressing.
An organic peroxide is added in an amount of preferably 0.005 to 5% by weight, more preferably 0.02 to 3% by weight based on VP. When an organic peroxide is added in a small amount, the polymerization rate tends to decrease causing a low productivity. And when added in a large amount, the peroxide remains as impurities after polymerization, which is not preferable in a product quality, and tends to cause trouble in preparation of a polymer having a relatively high molecular weight.
The organic peroxide may be added in a form of solid or liquid or in a form of an aqueous solution.
A sulfite is used as a reductant. The sulfite produces sulfate ion in a redox reaction, but the sulfate ion can be adsorbed and removed easily by using an anion exchange resin. Therefore, the sulfite is suitable in the present invention as compared with other reductants. As the sulfite, for example, an ammonium salt of a sulfurous acid comprising sulfurous acid, thiosulfurous acid, hyposulfurous acid and metasulfurous acid, an alkaline metal salt thereof (for example, a sodium salt or a potassium salt thereof, an alkaline earth metal salt thereof (for example, a magnesium salt or a calcium salt thereof can be employed. Among those mentioned above, ammonium sulfite is more preferable because does not turn into an ash content and can be removed easily for the reason of its high volatility.
The sulfite is added in an amount of preferably 0.005 to 10% by weight, more preferably 0.02 to 7% by weight based on VP. When the sulfite is added in a small amount, a high polymerization ratio is difficult to be obtained and non-reacting monomers tend to
Fujise Keiichi
Hamaguchi Itsuko
Kitada Akira
Dai-Ichi Kogyo Seiyaku Co. Ltd.
Pezzuto Helen L.
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