CA2184837A1 - Preparation of low-pyrrolidone, low molecular weight homopolymers of n-vinylpyrrolidone - Google Patents
Preparation of low-pyrrolidone, low molecular weight homopolymers of n-vinylpyrrolidoneInfo
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- CA2184837A1 CA2184837A1 CA 2184837 CA2184837A CA2184837A1 CA 2184837 A1 CA2184837 A1 CA 2184837A1 CA 2184837 CA2184837 CA 2184837 CA 2184837 A CA2184837 A CA 2184837A CA 2184837 A1 CA2184837 A1 CA 2184837A1
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- Prior art keywords
- weight
- polymerization
- vinylpyrrolidone
- water
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
- C08F126/00—Homopolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a single or double bond to nitrogen or by a heterocyclic ring containing nitrogen
- C08F126/06—Homopolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a single or double bond to nitrogen or by a heterocyclic ring containing nitrogen by a heterocyclic ring containing nitrogen
- C08F126/10—N-Vinyl-pyrrolidone
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- Health & Medical Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Medicinal Chemistry (AREA)
- Polymers & Plastics (AREA)
- Organic Chemistry (AREA)
- Addition Polymer Or Copolymer, Post-Treatments, Or Chemical Modifications (AREA)
- Detergent Compositions (AREA)
- Polymerisation Methods In General (AREA)
Abstract
A process for the preparation of low-pyrrolidone, low, molecular weight homopolymers of N-vinylpyrrolidone by solution polymeriza-tion in aqueous medium in the presence of a compound which forms free radicals, wherein the polymerization is carried out in the presence of a polymerization regulator which has a transfer constant Cx greater than 0.01.
Description
~ - 21 84~37 The preparation of 1 ~ ~yLlulidone, low molecular weight homo-polymers of N-vinylpyrrolidone The present invention relates to a process for the preparation of low molecular weight homopolymers of N-vinylpyrrolidone by solu-tion polymerization in aqueous medLum in the presence of a com-pound which forms free radical~.
10 The preparation of low molecular weight polyvinylpyrrolidone by polymerization in ~ ()hol ir solution i8 disclosed, for example, in US-A 4 053 696. In thL~ oal-e, the regulating action of the solvent isu~Luua:.ol is used to control the molecular weight.
Although this process gives products with a relatively small con-tent of impurities, c~clre~lly of 2-pyrrolidone, it has the dis-~dvantage that relatively large amounts of isu~u~l~ol result and must be either disposed of or purified by distillation.
~ow molecular weight polyvinylpyrrolidone has to date been pre-20 pared in aqueous solution in the presence of hydrogen peroxide as initiator as rle~- rihe~l, for example, in US-A 2 335 454.
In this process, H2û2 is both initiator and regulator. The molecu-lar weight of the polyvinylpyrrolidone polymers prepared in this way is thus adjusted by the H2û2 uu-lu~ Lion, with low molecular weights being produced by high H22 c:o..~ LlilLions and vice versa.
The polymerization n~ ~-^ in this process is described in Polymers of N-vinylpyrrolidone, Synthesi~, Characterization and Uses, F. Haaf, A. Sanner, F. Straub, Polymer Journal 17 (1985) 30 143-152 . According to this '~ni -1~ one mole of 2-pyrrolidone is produced per mole of H202 employed, ie. polyvinylpyrrolidone polymers with low molecular weights in particular contain high concentrations of 2-pyrrolidone as impurity.
DE-A 1 021 121 describes the preparation of low molecular weight polyvinylpyrrolidones using azo initiators, with the polymeriza-tion being carried out in alcohol/water mixtures.
W0 94/26796 disclosea the preparation of low molecular weight 40 copolymers of N-vinylimidazole and N-vinylpyrrolidone using an azo initiator in aqueous solution in the presence of a sulfur compound as regulator.
It is an object o the present invention to find an improved pro-cess ~or the preparation of low molecular weight homopolymers of N-vinylpyrrolidone by solution polymerization in aqueous medium.
-. 2 21 84837 We have found that thi~ object i5 achieved by a process for the preparation of low 1 ec~l Ar weight homopolymers of N-vinylpyr-rolidone in aqueous medium using a compound which forms free radicals, wherein the polymerization is carried out in the pres-ence of polymerization regulators which have a transfer constantCx greater than 0.01.
Preferably chosen as, which form free radicals are water-soluble azo initiators such as the following which are com-10 mercially available: 2, 2 ' -azobis [ 2- ~ 2-imidazolin-2-yl ) propane ]
dihydrochloride, 2, 2 ' -azobis ~ 2-amidinopropane ) dihydrochloride, disodium 4, 4 ' -azobis ( 4 yill.vp~r.Lanoate ) or 2, 2 ' -azobis ( i80-butyramide ) dihydrate .
Also ~uitable are azo - which are insoluble or have only limited ~olubility in water, such as 2,2'-azobisiso~.,LyLv.litrile, 2, 2 ' -azobis ( 2-methylbutyronitrile ), dimethyl 2, 2 ' -azobisiso-butyrate, 2, 2 ' -azobis ( 4-methoxy-2, 4-dimethylvaleronitrile ), 2, 2 ' -azobis ( 2, 4-dimethylvaleronitrile ) or 1,1 ' -azobis ( 1-cyclo-20 h~YAn~`Arh~n~ trile) .
Also equally suitable as formers of free radicals are sy-mmetric peroxides, for example di-tert-butyl peroxide, di-bert-amyl per-oxide or diacyl peroxides such as dilauroyl, didecanoyl, diben-zoyl and dioctanoyl peroxides, and perester~ such as tert-butyl peroxypivalate, tert-amyl peroxypivalate, LeLL buLyl peroxy-benzoate or tert-butyl ~-v,.y. ~ n~uA~te.
The poly-merization ~ ~-LuL.s should be chosen 80 that the 30 half-lives for ~ J i tion of the initiator are from 0 . 5 to 5 hours, which is normally the case in the range from 60 to 130-C.
The polymerization can, where appropriate, also be carried out under elevated pressure.
The azo . ullds can be employed in amounts of from 0.1 to 10~
by weight (based on the amount of N-vinylpyrrolidone), preferably 0 . 5 to 5~ by weight . It is advisable to employ the azo as solution, in which case the water-soluble azo ~ '- are preferably employed in purely aqueous solution. It is also pos-40 sible to use Cl-C4-alkanols, preferably methanol, ethanol or iso-propanol, where appropriate as mixture with water, as solvents, it being possible to employ the organic solvents preferably for the azo _ ~c which are insoluble or have only low solubility in water.
10 The preparation of low molecular weight polyvinylpyrrolidone by polymerization in ~ ()hol ir solution i8 disclosed, for example, in US-A 4 053 696. In thL~ oal-e, the regulating action of the solvent isu~Luua:.ol is used to control the molecular weight.
Although this process gives products with a relatively small con-tent of impurities, c~clre~lly of 2-pyrrolidone, it has the dis-~dvantage that relatively large amounts of isu~u~l~ol result and must be either disposed of or purified by distillation.
~ow molecular weight polyvinylpyrrolidone has to date been pre-20 pared in aqueous solution in the presence of hydrogen peroxide as initiator as rle~- rihe~l, for example, in US-A 2 335 454.
In this process, H2û2 is both initiator and regulator. The molecu-lar weight of the polyvinylpyrrolidone polymers prepared in this way is thus adjusted by the H2û2 uu-lu~ Lion, with low molecular weights being produced by high H22 c:o..~ LlilLions and vice versa.
The polymerization n~ ~-^ in this process is described in Polymers of N-vinylpyrrolidone, Synthesi~, Characterization and Uses, F. Haaf, A. Sanner, F. Straub, Polymer Journal 17 (1985) 30 143-152 . According to this '~ni -1~ one mole of 2-pyrrolidone is produced per mole of H202 employed, ie. polyvinylpyrrolidone polymers with low molecular weights in particular contain high concentrations of 2-pyrrolidone as impurity.
DE-A 1 021 121 describes the preparation of low molecular weight polyvinylpyrrolidones using azo initiators, with the polymeriza-tion being carried out in alcohol/water mixtures.
W0 94/26796 disclosea the preparation of low molecular weight 40 copolymers of N-vinylimidazole and N-vinylpyrrolidone using an azo initiator in aqueous solution in the presence of a sulfur compound as regulator.
It is an object o the present invention to find an improved pro-cess ~or the preparation of low molecular weight homopolymers of N-vinylpyrrolidone by solution polymerization in aqueous medium.
-. 2 21 84837 We have found that thi~ object i5 achieved by a process for the preparation of low 1 ec~l Ar weight homopolymers of N-vinylpyr-rolidone in aqueous medium using a compound which forms free radicals, wherein the polymerization is carried out in the pres-ence of polymerization regulators which have a transfer constantCx greater than 0.01.
Preferably chosen as, which form free radicals are water-soluble azo initiators such as the following which are com-10 mercially available: 2, 2 ' -azobis [ 2- ~ 2-imidazolin-2-yl ) propane ]
dihydrochloride, 2, 2 ' -azobis ~ 2-amidinopropane ) dihydrochloride, disodium 4, 4 ' -azobis ( 4 yill.vp~r.Lanoate ) or 2, 2 ' -azobis ( i80-butyramide ) dihydrate .
Also ~uitable are azo - which are insoluble or have only limited ~olubility in water, such as 2,2'-azobisiso~.,LyLv.litrile, 2, 2 ' -azobis ( 2-methylbutyronitrile ), dimethyl 2, 2 ' -azobisiso-butyrate, 2, 2 ' -azobis ( 4-methoxy-2, 4-dimethylvaleronitrile ), 2, 2 ' -azobis ( 2, 4-dimethylvaleronitrile ) or 1,1 ' -azobis ( 1-cyclo-20 h~YAn~`Arh~n~ trile) .
Also equally suitable as formers of free radicals are sy-mmetric peroxides, for example di-tert-butyl peroxide, di-bert-amyl per-oxide or diacyl peroxides such as dilauroyl, didecanoyl, diben-zoyl and dioctanoyl peroxides, and perester~ such as tert-butyl peroxypivalate, tert-amyl peroxypivalate, LeLL buLyl peroxy-benzoate or tert-butyl ~-v,.y. ~ n~uA~te.
The poly-merization ~ ~-LuL.s should be chosen 80 that the 30 half-lives for ~ J i tion of the initiator are from 0 . 5 to 5 hours, which is normally the case in the range from 60 to 130-C.
The polymerization can, where appropriate, also be carried out under elevated pressure.
The azo . ullds can be employed in amounts of from 0.1 to 10~
by weight (based on the amount of N-vinylpyrrolidone), preferably 0 . 5 to 5~ by weight . It is advisable to employ the azo as solution, in which case the water-soluble azo ~ '- are preferably employed in purely aqueous solution. It is also pos-40 sible to use Cl-C4-alkanols, preferably methanol, ethanol or iso-propanol, where appropriate as mixture with water, as solvents, it being possible to employ the organic solvents preferably for the azo _ ~c which are insoluble or have only low solubility in water.
3 21 8~837 Water i5 used as polymerization medium and can contain up to 10%
by weight, preferably leas than 5% by weight, of the above-mentioned alkanols. The polymerization medium should contain only as much alcohol as is necessary for dissolving and adding the which form free radicals and are insoluble or have only limited solubility in water. Polymerization in purely aqueous medium using water-soluble azo ~ ' is particularly pre-f erred .
10 The polymerization is preferably carried out at a pH in the range from 6 to 9 in order to avoid hydrolysis of the N-vinylpyr-rolidone. It is therefore advisable to adjust the solutions of the starting materials, before the polymerization starts, to the suitable pH range with a suitable base, for example agueous sodium hydroxide solution.
Suitable polymerization regulators accordlng to the invention are those regulators which have a transfer constant Cx greater than 0.01, preferably from 0.2 to 50. For definition of the transfer 20 constant, see Polymer handbook, Ed. J. 3randrup and E.H. Immergut, 3rd Ed., Chapter II, page 81 et seq.
Examples of suitable regulators are allyl ~ ~ ' such as allyl alcohol or allyl chloride, aliphatic or araliphatic halohydro-carbons such as, for example, chloroform, carbon tetrachloride or benzyl bromide, or aldehydes such as acetaldehyde or croton-aldehyde, and saccharin.
The polymerization is preferably carried out in the presence of 30 polymeri2ation regulators which contain sulfur in bound form.
Examples of _.lds of this type are inorganic bisulfites, disulfites and dithionites or organic sulfides, disulfides, poly-sulfides, sulfoxides,sulfones and mercapto _.lds. The follow-ing polymerization regulators are mentioned by way of example:
di-n-butyl sulfide, di-n-octyl sulfide, diphenyl sulfide, thio-diglycol, ethylthioethanol, diisopropyl rli~llf;~ di-n-butyl disulfide, di-n-hexyl disulfide, diacetyl disulfide, 2,2'-thio-diethanol, di-t-butyl trisulfide and dimethyl sulfoxide. Com-pounds which are preferably used as polymerization regulators are 40 mercapto , dialkyl sulfides, dialkyl disulfidea and/or diaryl sulfides. Examples of these ' are ethyl thioglyco-late, cysteine, 2-mercaptoethanol, 3-mercapL-,~Luyanol, 3 - ~ o-1,2 ~Lc.panediol, ~ a~,L~,l,u~anol, mercaptoacetic acid, 3 ~dpL-~L~ionic ~cid, ~ oD~,cc;n;~ acid, thio-glycerol, thioacetic acid, thiourea and alkyl mercaptans such as n-butyl mercaptan, n-hexyl mercaptan or n-dodecyl mercaptan.
~ :. 21 84837 Polymerization regulators which are particularly preferably employed ~re mercapto alcohols and mercapto carboxylic acids.
The polymerization regulators are used in amounts of from 0.1 to 15, preferably 0.5 to 10, ~ by weight, based on the monomers used in the polymerization. It is, of course, also possible to use mixtures of the polymerization regulator to be employed according to the invention in the polymerization.
10 The monomers can be polymerized by conventional techniques, eg.
by batch polymerization in which l-vinylpyrrolidone, regulator and initiator are illLludu~ ed into a solvent and heated to the polymerization t - clLuLt~. The reaction mixture is stirred at the polymerization temperature until conversion i9 more than 99.9~. In this process it is also possible where appropriate to add the initiator only after the polymerization t~, dLULe: i8 reached .
Further variants of the polymeri2ation process comprise the feed 20 methods, which are preferably used. In these variants of the pro-cess, a solution of the polymerization regulator which contains sulfur in bound form, and a solution of initiator are added, con-tinuously or in portions, over a certain time to a mixture of vinylpyrrolidone and a solvent at the polymerization temperature.
However, it is also possible to meter a mixture of regulator and initiator into the initial mixture which has been heated to the polymerization temperature. Another method comprises adding the initiator to the initial mixture which is below or at the poly-merization ~ ~ elLULæ and adding only the regulator or a solu-30 tion of the regulator within a preset time to the reaction mix-ture after the polymerization t ~e.L~Ire is reached. Another variant of the feed technique comprises heating the initial mix-ture to a I ~lLULt~ at which the polymerization takes place and then adding regulator, initiator and monomer in separate feeds or together. With this techni~;ue, the initial mixture preferably consists of water, monomer and/or initiator and/or regulator or water alone. A particularly preferred feature according to the invention is one in which the polymerization regulators contain-ing sulur in bound form are metered in continuously or in por-40 tions during the polymerization of the monomers.
The weight average molecular weight M~, of the polyvinylpyrrolidonepolymers prepared in this way is in the range from 2000 to 50,000, preferably 5000 to gO,000. These polymers have K values of from 10 to 50 (determined as described in H. Fihel.LsulleL "Sys-tematik der CP1 llllos~n aufgrund ihrer Viskositat in Losung, Cellulose-Chemie 13 ~1932) 58-64 and 71-74). The solutions . . . . _ . . _ __ _ . . . . . . . _ _ ` ~: 2184837 resulting from the polymerization can be subjected to a physical or chemical deodorization after the polymerization process. 3y this is meant, inter alia, subsequent treatment of the polymer solution with steam to remove impurities from the solution. Sub-sequent chemical treatment entails the addition of polymerization initiators or mixtures of several polymerization initiators and heating of the polymer solutions where appropriate to tempera-tures above the polymerization ~ uLe.
10 The aqueous polymer 501utions are normally prepared in such a way that they have solids contents of from 20 to 60% by weight.
The aqueous polyvinylpyrrolidone solutions can, where approp-riate, be ~ul-v~L~ed into solid powders by a prior art drying pro-cess. Drying processes which are suitable for producing powdered polymers are all those suitable for drying from aqueous solution.
Preferred pLuces3~J are spray drying, fluidized bed drying, drum drying and belt drying, while ~Luc~ a which are less preferred but can also be used are freeze drying and freeze cu..cer -L~Ling.
The N-vinylpyrrolidone homopolymers obtainable by the process according to the invention have low contents of impurities such as 2-pyrrolidone or N-vinylpyrrolidone. Their contents of 2-pyrrolidone are preferably below 0.596 by weight, based on the polymer .
Pre~erred areas of application of the low le~-llAr weight and, at the same time, lc tJyLLUlidOne polyvinylpyrrolidone obtained according to the invention are cosmetic and rh~r~ utical com-30 positions, in particular 3i,0LelU~_ stable disinfectants complexedwith iodine, and detergent additives.
The residual monomer contents mentioned in the following examples were determined by gas ~hL~ D~L~.~hy.
Example 1 The following solutions were first prepared:
40 1. Monomer feed consisting of 500 g of N-vinylpyrrolidone and 120 g of water.
2. Initiator feed 1 consisting o 7.5 9 of 2,2'-azobis(2-methyl-butyronitrile) dissolved in 80 g of isuyLu~dllol.
6 ~ ~ 8~837 3. Regulator feed 1 consisting of 50 g of water and 5 g of 2 . a~Loe~hanol.
by weight, preferably leas than 5% by weight, of the above-mentioned alkanols. The polymerization medium should contain only as much alcohol as is necessary for dissolving and adding the which form free radicals and are insoluble or have only limited solubility in water. Polymerization in purely aqueous medium using water-soluble azo ~ ' is particularly pre-f erred .
10 The polymerization is preferably carried out at a pH in the range from 6 to 9 in order to avoid hydrolysis of the N-vinylpyr-rolidone. It is therefore advisable to adjust the solutions of the starting materials, before the polymerization starts, to the suitable pH range with a suitable base, for example agueous sodium hydroxide solution.
Suitable polymerization regulators accordlng to the invention are those regulators which have a transfer constant Cx greater than 0.01, preferably from 0.2 to 50. For definition of the transfer 20 constant, see Polymer handbook, Ed. J. 3randrup and E.H. Immergut, 3rd Ed., Chapter II, page 81 et seq.
Examples of suitable regulators are allyl ~ ~ ' such as allyl alcohol or allyl chloride, aliphatic or araliphatic halohydro-carbons such as, for example, chloroform, carbon tetrachloride or benzyl bromide, or aldehydes such as acetaldehyde or croton-aldehyde, and saccharin.
The polymerization is preferably carried out in the presence of 30 polymeri2ation regulators which contain sulfur in bound form.
Examples of _.lds of this type are inorganic bisulfites, disulfites and dithionites or organic sulfides, disulfides, poly-sulfides, sulfoxides,sulfones and mercapto _.lds. The follow-ing polymerization regulators are mentioned by way of example:
di-n-butyl sulfide, di-n-octyl sulfide, diphenyl sulfide, thio-diglycol, ethylthioethanol, diisopropyl rli~llf;~ di-n-butyl disulfide, di-n-hexyl disulfide, diacetyl disulfide, 2,2'-thio-diethanol, di-t-butyl trisulfide and dimethyl sulfoxide. Com-pounds which are preferably used as polymerization regulators are 40 mercapto , dialkyl sulfides, dialkyl disulfidea and/or diaryl sulfides. Examples of these ' are ethyl thioglyco-late, cysteine, 2-mercaptoethanol, 3-mercapL-,~Luyanol, 3 - ~ o-1,2 ~Lc.panediol, ~ a~,L~,l,u~anol, mercaptoacetic acid, 3 ~dpL-~L~ionic ~cid, ~ oD~,cc;n;~ acid, thio-glycerol, thioacetic acid, thiourea and alkyl mercaptans such as n-butyl mercaptan, n-hexyl mercaptan or n-dodecyl mercaptan.
~ :. 21 84837 Polymerization regulators which are particularly preferably employed ~re mercapto alcohols and mercapto carboxylic acids.
The polymerization regulators are used in amounts of from 0.1 to 15, preferably 0.5 to 10, ~ by weight, based on the monomers used in the polymerization. It is, of course, also possible to use mixtures of the polymerization regulator to be employed according to the invention in the polymerization.
10 The monomers can be polymerized by conventional techniques, eg.
by batch polymerization in which l-vinylpyrrolidone, regulator and initiator are illLludu~ ed into a solvent and heated to the polymerization t - clLuLt~. The reaction mixture is stirred at the polymerization temperature until conversion i9 more than 99.9~. In this process it is also possible where appropriate to add the initiator only after the polymerization t~, dLULe: i8 reached .
Further variants of the polymeri2ation process comprise the feed 20 methods, which are preferably used. In these variants of the pro-cess, a solution of the polymerization regulator which contains sulfur in bound form, and a solution of initiator are added, con-tinuously or in portions, over a certain time to a mixture of vinylpyrrolidone and a solvent at the polymerization temperature.
However, it is also possible to meter a mixture of regulator and initiator into the initial mixture which has been heated to the polymerization temperature. Another method comprises adding the initiator to the initial mixture which is below or at the poly-merization ~ ~ elLULæ and adding only the regulator or a solu-30 tion of the regulator within a preset time to the reaction mix-ture after the polymerization t ~e.L~Ire is reached. Another variant of the feed technique comprises heating the initial mix-ture to a I ~lLULt~ at which the polymerization takes place and then adding regulator, initiator and monomer in separate feeds or together. With this techni~;ue, the initial mixture preferably consists of water, monomer and/or initiator and/or regulator or water alone. A particularly preferred feature according to the invention is one in which the polymerization regulators contain-ing sulur in bound form are metered in continuously or in por-40 tions during the polymerization of the monomers.
The weight average molecular weight M~, of the polyvinylpyrrolidonepolymers prepared in this way is in the range from 2000 to 50,000, preferably 5000 to gO,000. These polymers have K values of from 10 to 50 (determined as described in H. Fihel.LsulleL "Sys-tematik der CP1 llllos~n aufgrund ihrer Viskositat in Losung, Cellulose-Chemie 13 ~1932) 58-64 and 71-74). The solutions . . . . _ . . _ __ _ . . . . . . . _ _ ` ~: 2184837 resulting from the polymerization can be subjected to a physical or chemical deodorization after the polymerization process. 3y this is meant, inter alia, subsequent treatment of the polymer solution with steam to remove impurities from the solution. Sub-sequent chemical treatment entails the addition of polymerization initiators or mixtures of several polymerization initiators and heating of the polymer solutions where appropriate to tempera-tures above the polymerization ~ uLe.
10 The aqueous polymer 501utions are normally prepared in such a way that they have solids contents of from 20 to 60% by weight.
The aqueous polyvinylpyrrolidone solutions can, where approp-riate, be ~ul-v~L~ed into solid powders by a prior art drying pro-cess. Drying processes which are suitable for producing powdered polymers are all those suitable for drying from aqueous solution.
Preferred pLuces3~J are spray drying, fluidized bed drying, drum drying and belt drying, while ~Luc~ a which are less preferred but can also be used are freeze drying and freeze cu..cer -L~Ling.
The N-vinylpyrrolidone homopolymers obtainable by the process according to the invention have low contents of impurities such as 2-pyrrolidone or N-vinylpyrrolidone. Their contents of 2-pyrrolidone are preferably below 0.596 by weight, based on the polymer .
Pre~erred areas of application of the low le~-llAr weight and, at the same time, lc tJyLLUlidOne polyvinylpyrrolidone obtained according to the invention are cosmetic and rh~r~ utical com-30 positions, in particular 3i,0LelU~_ stable disinfectants complexedwith iodine, and detergent additives.
The residual monomer contents mentioned in the following examples were determined by gas ~hL~ D~L~.~hy.
Example 1 The following solutions were first prepared:
40 1. Monomer feed consisting of 500 g of N-vinylpyrrolidone and 120 g of water.
2. Initiator feed 1 consisting o 7.5 9 of 2,2'-azobis(2-methyl-butyronitrile) dissolved in 80 g of isuyLu~dllol.
6 ~ ~ 8~837 3. Regulator feed 1 consisting of 50 g of water and 5 g of 2 . a~Loe~hanol.
4 . Initiator feed 2 consisting of 2 . 5 g of 2, 2 ' -azobis ( 2-methyl-butyronLtrile) dissolved in 20 g of isQpropanol.
5 . Regulator feed 2 consisting of 80 g of water and 1. 7 g o 2 -mercaptoethanol .
10 The pH of solutions 1, 3 and 5 was ad~usted to the range from 6 to 8 with dilute sodium hydroxide solution.
800 g of water were placed in a stirred laboratory vessel, flushed with nitrogen and heated to an internal ~ aL-lre of 85C. Then the monomer feed, regulator feed 1 and initiator feed 1 were started simultaneously and added at a constant rate simul-taneously over the course of 3 hours. To complete the polymeriza-tion, subsequently initiator eed 2 was added and regulator feed 2 was added over the course of half an hour. The polymerization 20 temperature of 85 C was maintained for a further 2 hours. Volatile impurities were removed by steam distillation, distilling out 500 g of water.
The resulting colorless and low-viscosity solution had ~ solids content of 35% by weight (26% by weight), and the E~ value of the product (measured at a vvnoe--Lr~Lion of 1% by weight in water was 20.0 (20.0). The impurities found were 0.04% by weight (0.024% by weight) of N-vinylpyrrolidone and 0.087% by weight (0.056% by weight) of pyrrolidone.
The f iyures in parentheses relate to a repeat test .
Example 2 The following solutions were first prepared:
1. Monomer feed consisting of 500 g of N-vinylpyrrolidone and 120 g of water.
2. Initiator feed 1 consisting of 7.5 g of 2,2~-azobis(2-amidi-nopropane) dihydrochloride dissolved in 170 g of water.
3. Regulator feed consisting of 50 g of water and 5 g of 2-mercaptoethanol .
4 . Initiator feed 2 consLsting of 2 . 5 g of 2, 2 ' -azobis ( 2-amidi-nopropane) dihydrochloride dissolved in 50 g of water.
The pH of all the 501ution5 was adjusted to the range from 6 to 8 with dilute sodium hydroxide solution.
The procedure wa8 as in Example 1 but without regulator feed 2.
The resulting colorless and low-viscosity solution had a soiids 10 content of 24.0% by weight, and the R value of the product (measured at a cu~ tion of 1% by weight in water) was 21.7.
The impurities found were 0.014% by weight of N-vinylpyrrolidone nnd 0.09% by weight of pyrrolidone.
Example 3 The solutions were the same as used in Example 2 but 10 g of 2-mercaptoethanol were employed in the regulator feed.
20 The ùLv-eduLe was as in Example 1 but without regulator feed 2.
The resulting colorless and low-viscogity solution had a solids content of 25.4% by weight, and the K value of the product (mea~ured at ~ uu..~e~.~L~ion of 1% by weight in water) was 17 . 6 .
The impurities found were 0.015% by weight of N-vinylpyrrolidone and 0 . 095% by weight of pyrrolidone .
Example 4 30 The solutions were the same as used in Example 2 but 20 g of 2-mercaptoethanol were employed in the regulator feed.
The uLuc eduL~ was as in Example 1 but without regulator feed 2 .
The resulting colorless and low-viscosity solution had a solids content of 31% by weight (22% by weight)~ and the R value of thê
product (measured at a concentration of 1% by weight in water) was 13.7 (14.6). The impurities found were 0.024% by weight (0.033% by weight) of N-vinylpyrrolidone and 0.072% by weight 40 (o.11% by weight) of pyrrolidone.
The figures in parentheses relate to a repeat test.
Example 5 The following solutions were first prepared:
,. . .
8 2 ~ ~4837 1. InitLal mixture consi5ting of 500 g of N-vinylpyrrolidone, 1100 9 of water, 7.5 g of 2,2~-azobis(2-am1~1~nnrropane) di-hydrochloride and 10 g of 2 ~ a~Lo~thanol .
2. Initiator feed consisting of 2.5 g of 2,2'-azobis(2-amidino-propane) dihydrochloride dissolved in 50 g of water.
3 . Regulator feed consisting of 80 g of water and 1. ? g of 2-mercaptoethanol .
The pH of all the solutions was adjusted to the range from 6 to 8 with dilute sodium hydroxide solution.
The initial mixture was placed in a stirred laboratory vessel, flushed with nitrogen and heated to an internal f~ LUlu of 85 C. The temperature was maintained for half an hour and then, to complete the polymerization, the initiator feed and the regulator feed were added simultaneously over the course of half an hour.
Volatile impurities were removed by steam distillation, during 20 which 500 g of water distilled out.
The resulting colorless and low-viscosity solution had a solids content of 24.7% by weight, and the K value of the product (measured at a .wn~e~,~L.,Lion of 1% by weight in water) was 49 . 4 .
The impurities found were 0.045% by weight of N-vinylpyrrolidone and 0 . 005% by weight of pyrrolidone .
Example 6 30 The following solutions were first prepared:
1. Initial mixture consisting of 500 g of N-vinylpyrrolidone and 1200 g of water.
2 . Initiator feed consisting of 5 g of 2, 2 '-azobis ( 2-methylbuty-ronitrile ) dissolved in 80 g o~ water .
3. Regulator feed consisting of 100 g of water and 15 g of 2 -mercaptoethanol .
The pH of solutions 1 and 3 was adjusted to the range from 6 to 8 with dilute sodium hydroxide solution.
Ihe initial mixture was placed in a stirred laboratory vessel, flushed with nitrogen and heated to an internal ~l aLULtS of 85 C. The initiator feed and the regulator feed were then started simultaneously and added at a constant rate ~imultaneously over _ . .. . _ . _ . , ... . _ _ _ _ _ _ . .
2 ~ 84837 the course of 3 hours. To complet- the polymerization, the poLy-merization t - aLule of 85 C was maintained for a further 2 hours. Volatile impurities were removed by ql~hs~q~nt steam distillation, during which approximately 500 g of water distilled out .
The resulting colorless and low-viscosity solution had a solids content of 25% by weight, and the ~ value of the product (measured at a cu..~e-~Ll~lLion of 1% by weight in water) was 20Ø
10 The impurities found were 0 . 05& by weight of N-vinylpyrrolidone and 0.095% by weight of pyrrolidone Example 7 The solutions were the same a~ used in Example 3 but 7 . 5 g and 2 . 5 g of disodium 4, 4 ~ -azohis ( 4-cyanopentanoate ) were used in initiator feeds 1 and 2.
The procedure was A8 in Example 1.
The resulting colorless and low-viscosity solution had a solids content of 23 . 5~ by weight, and the }t value of the product (measured at a concentration of 1% by weight in water) was 17.8.
The impurities found were 0 . 007% by weight of N-vinylpyrrolidone and 0 05~ by weight of pyrrolidone.
Example 8 The following solutions were first prepared:
1. Initial mixture consisting of 500 g of N-vinylpyrrolidone and 1200 g of water.
2. Initiator feed consisting of 6.5 g of tertiary-butyl peroxy-pivalate dissolved in 80 g of isuuLu~anc,l.
3. Regulator feed consisting of 100 g of water and 30 g of 2 c~l LoeLhanol.
40 The pH of the solution was ad~usted to the range from 6 to 8 with dilute sodium hydroxide solution.
The initial mixture was placed in a stirred laboratory vessel, flushed with nitrogen and heated to an internal I a-LIre of 80 C. The initiator feed and the regulator feed were then started simultaneously and added at a constant rate simultaneously over the course of 3 hours. To complete the polymerization, the _ _ _ _ _ _ _ _ ~184~37 polymerization, aLuL~: of 80 C was maintained for a further 2 hours. volatile impurities were removed by subsequent steam distillation, during which 500 g of water distilled out.
The resulting colorlesa and low-viscosity solution had a solids content of 28% by weight, and the }~ value of the product ~measured at a ~u~ LLation of 1~ by weight in water) was 49.4.
The impurities found were 0 . 0696 by weight of N-vinylpyrrolidone and 0.066% by weight of pyrrolidone.
Example 9 The following solutions were first prepared:
1. Initial mixture consisting of S00 g of N-vinylpyrrolidone and 1200 g of water.
2. Initiator feed consisting of 6.5 g of tertiary-butyl peroxy-pivalate dissolved in 80 g of isopropanol.
3. Regulator feed consisting of 100 g of water and 30 g of sodium sulfite.
The p~ of the solutions wa i adjusted to the range from 6 to 8 with dilute sodium hydroxide solution.
The initial mixture was placed in a stirred laboratory vessel, f lushed with nitrogen and heated to an internal temperature of 85 C. The ~ aLuLe was maintained for half an hour and then, to 30 complete the polymerization, the initiator feed and the regulator feed were added simultaneously over the course of half an hour.
Volatile impurities were removed by steam distillation, during which 500 g of water distilled out.
The resulting colorless and low-viscosity solution had a solids content of 2596 by weight, and the K value of the product (mea-sured at a ~ u.lcenLLaLion of 1% by weight in water) was 29.4. The impurities found were 0.05% by weight of N-vinylpyrrolidone and 0.06~ by weight of pyrrolidone.
Comparative Example The following solutions were first prepared:
1. Initial mixture consisting of 500 g of N-vinylpyrrolidone and 1000 g of water.
2. Initiator feed 1 consisting of 65 9 of H22 (306 by weight) and 0.6 g of CuC12 aolution (0.01% by weight).
3. Base feed consi5ting of 16 g of sodium hydroxide dissolved in 144 g of water.
4. Initiator feed 2 consi5ting of 13 g of H202 (30% by weight) and 0.3 g of CuC12 solution (0.019~ by weight).
5. Initiator feed 3 consisting of 3.3 g of H22 (3096 by weight).
The initial mixture was placed in a stirred laboratory vessel, flushed with nitrogen and heated to an internal t~, aLure of 80 C. Then the initiator feed and the regulator feed were started simultaneously and added at a constant rate simultaneously over the course of 3 hours. To complete the polymerization, the poly-meri2~ation 1 , aLuLe of 80 C waa maintained for a further 2 hours. Volatile impurities were removed by ~ L steam distillation, during which 500 g of water distilled out.
The resulting colorless and low-viscosity solution had a solids content of 2096, and the R value of the product (measured at a ~vl-.ellL~ aLion of 1% by weight in water) was 16.4 . The impurities found were 0.0396 of N-vinylpyrrolidone and 2.259~ of pyrrolidone.
10 The pH of solutions 1, 3 and 5 was ad~usted to the range from 6 to 8 with dilute sodium hydroxide solution.
800 g of water were placed in a stirred laboratory vessel, flushed with nitrogen and heated to an internal ~ aL-lre of 85C. Then the monomer feed, regulator feed 1 and initiator feed 1 were started simultaneously and added at a constant rate simul-taneously over the course of 3 hours. To complete the polymeriza-tion, subsequently initiator eed 2 was added and regulator feed 2 was added over the course of half an hour. The polymerization 20 temperature of 85 C was maintained for a further 2 hours. Volatile impurities were removed by steam distillation, distilling out 500 g of water.
The resulting colorless and low-viscosity solution had ~ solids content of 35% by weight (26% by weight), and the E~ value of the product (measured at a vvnoe--Lr~Lion of 1% by weight in water was 20.0 (20.0). The impurities found were 0.04% by weight (0.024% by weight) of N-vinylpyrrolidone and 0.087% by weight (0.056% by weight) of pyrrolidone.
The f iyures in parentheses relate to a repeat test .
Example 2 The following solutions were first prepared:
1. Monomer feed consisting of 500 g of N-vinylpyrrolidone and 120 g of water.
2. Initiator feed 1 consisting of 7.5 g of 2,2~-azobis(2-amidi-nopropane) dihydrochloride dissolved in 170 g of water.
3. Regulator feed consisting of 50 g of water and 5 g of 2-mercaptoethanol .
4 . Initiator feed 2 consLsting of 2 . 5 g of 2, 2 ' -azobis ( 2-amidi-nopropane) dihydrochloride dissolved in 50 g of water.
The pH of all the 501ution5 was adjusted to the range from 6 to 8 with dilute sodium hydroxide solution.
The procedure wa8 as in Example 1 but without regulator feed 2.
The resulting colorless and low-viscosity solution had a soiids 10 content of 24.0% by weight, and the R value of the product (measured at a cu~ tion of 1% by weight in water) was 21.7.
The impurities found were 0.014% by weight of N-vinylpyrrolidone nnd 0.09% by weight of pyrrolidone.
Example 3 The solutions were the same as used in Example 2 but 10 g of 2-mercaptoethanol were employed in the regulator feed.
20 The ùLv-eduLe was as in Example 1 but without regulator feed 2.
The resulting colorless and low-viscogity solution had a solids content of 25.4% by weight, and the K value of the product (mea~ured at ~ uu..~e~.~L~ion of 1% by weight in water) was 17 . 6 .
The impurities found were 0.015% by weight of N-vinylpyrrolidone and 0 . 095% by weight of pyrrolidone .
Example 4 30 The solutions were the same as used in Example 2 but 20 g of 2-mercaptoethanol were employed in the regulator feed.
The uLuc eduL~ was as in Example 1 but without regulator feed 2 .
The resulting colorless and low-viscosity solution had a solids content of 31% by weight (22% by weight)~ and the R value of thê
product (measured at a concentration of 1% by weight in water) was 13.7 (14.6). The impurities found were 0.024% by weight (0.033% by weight) of N-vinylpyrrolidone and 0.072% by weight 40 (o.11% by weight) of pyrrolidone.
The figures in parentheses relate to a repeat test.
Example 5 The following solutions were first prepared:
,. . .
8 2 ~ ~4837 1. InitLal mixture consi5ting of 500 g of N-vinylpyrrolidone, 1100 9 of water, 7.5 g of 2,2~-azobis(2-am1~1~nnrropane) di-hydrochloride and 10 g of 2 ~ a~Lo~thanol .
2. Initiator feed consisting of 2.5 g of 2,2'-azobis(2-amidino-propane) dihydrochloride dissolved in 50 g of water.
3 . Regulator feed consisting of 80 g of water and 1. ? g of 2-mercaptoethanol .
The pH of all the solutions was adjusted to the range from 6 to 8 with dilute sodium hydroxide solution.
The initial mixture was placed in a stirred laboratory vessel, flushed with nitrogen and heated to an internal f~ LUlu of 85 C. The temperature was maintained for half an hour and then, to complete the polymerization, the initiator feed and the regulator feed were added simultaneously over the course of half an hour.
Volatile impurities were removed by steam distillation, during 20 which 500 g of water distilled out.
The resulting colorless and low-viscosity solution had a solids content of 24.7% by weight, and the K value of the product (measured at a .wn~e~,~L.,Lion of 1% by weight in water) was 49 . 4 .
The impurities found were 0.045% by weight of N-vinylpyrrolidone and 0 . 005% by weight of pyrrolidone .
Example 6 30 The following solutions were first prepared:
1. Initial mixture consisting of 500 g of N-vinylpyrrolidone and 1200 g of water.
2 . Initiator feed consisting of 5 g of 2, 2 '-azobis ( 2-methylbuty-ronitrile ) dissolved in 80 g o~ water .
3. Regulator feed consisting of 100 g of water and 15 g of 2 -mercaptoethanol .
The pH of solutions 1 and 3 was adjusted to the range from 6 to 8 with dilute sodium hydroxide solution.
Ihe initial mixture was placed in a stirred laboratory vessel, flushed with nitrogen and heated to an internal ~l aLULtS of 85 C. The initiator feed and the regulator feed were then started simultaneously and added at a constant rate ~imultaneously over _ . .. . _ . _ . , ... . _ _ _ _ _ _ . .
2 ~ 84837 the course of 3 hours. To complet- the polymerization, the poLy-merization t - aLule of 85 C was maintained for a further 2 hours. Volatile impurities were removed by ql~hs~q~nt steam distillation, during which approximately 500 g of water distilled out .
The resulting colorless and low-viscosity solution had a solids content of 25% by weight, and the ~ value of the product (measured at a cu..~e-~Ll~lLion of 1% by weight in water) was 20Ø
10 The impurities found were 0 . 05& by weight of N-vinylpyrrolidone and 0.095% by weight of pyrrolidone Example 7 The solutions were the same a~ used in Example 3 but 7 . 5 g and 2 . 5 g of disodium 4, 4 ~ -azohis ( 4-cyanopentanoate ) were used in initiator feeds 1 and 2.
The procedure was A8 in Example 1.
The resulting colorless and low-viscosity solution had a solids content of 23 . 5~ by weight, and the }t value of the product (measured at a concentration of 1% by weight in water) was 17.8.
The impurities found were 0 . 007% by weight of N-vinylpyrrolidone and 0 05~ by weight of pyrrolidone.
Example 8 The following solutions were first prepared:
1. Initial mixture consisting of 500 g of N-vinylpyrrolidone and 1200 g of water.
2. Initiator feed consisting of 6.5 g of tertiary-butyl peroxy-pivalate dissolved in 80 g of isuuLu~anc,l.
3. Regulator feed consisting of 100 g of water and 30 g of 2 c~l LoeLhanol.
40 The pH of the solution was ad~usted to the range from 6 to 8 with dilute sodium hydroxide solution.
The initial mixture was placed in a stirred laboratory vessel, flushed with nitrogen and heated to an internal I a-LIre of 80 C. The initiator feed and the regulator feed were then started simultaneously and added at a constant rate simultaneously over the course of 3 hours. To complete the polymerization, the _ _ _ _ _ _ _ _ ~184~37 polymerization, aLuL~: of 80 C was maintained for a further 2 hours. volatile impurities were removed by subsequent steam distillation, during which 500 g of water distilled out.
The resulting colorlesa and low-viscosity solution had a solids content of 28% by weight, and the }~ value of the product ~measured at a ~u~ LLation of 1~ by weight in water) was 49.4.
The impurities found were 0 . 0696 by weight of N-vinylpyrrolidone and 0.066% by weight of pyrrolidone.
Example 9 The following solutions were first prepared:
1. Initial mixture consisting of S00 g of N-vinylpyrrolidone and 1200 g of water.
2. Initiator feed consisting of 6.5 g of tertiary-butyl peroxy-pivalate dissolved in 80 g of isopropanol.
3. Regulator feed consisting of 100 g of water and 30 g of sodium sulfite.
The p~ of the solutions wa i adjusted to the range from 6 to 8 with dilute sodium hydroxide solution.
The initial mixture was placed in a stirred laboratory vessel, f lushed with nitrogen and heated to an internal temperature of 85 C. The ~ aLuLe was maintained for half an hour and then, to 30 complete the polymerization, the initiator feed and the regulator feed were added simultaneously over the course of half an hour.
Volatile impurities were removed by steam distillation, during which 500 g of water distilled out.
The resulting colorless and low-viscosity solution had a solids content of 2596 by weight, and the K value of the product (mea-sured at a ~ u.lcenLLaLion of 1% by weight in water) was 29.4. The impurities found were 0.05% by weight of N-vinylpyrrolidone and 0.06~ by weight of pyrrolidone.
Comparative Example The following solutions were first prepared:
1. Initial mixture consisting of 500 g of N-vinylpyrrolidone and 1000 g of water.
2. Initiator feed 1 consisting of 65 9 of H22 (306 by weight) and 0.6 g of CuC12 aolution (0.01% by weight).
3. Base feed consi5ting of 16 g of sodium hydroxide dissolved in 144 g of water.
4. Initiator feed 2 consi5ting of 13 g of H202 (30% by weight) and 0.3 g of CuC12 solution (0.019~ by weight).
5. Initiator feed 3 consisting of 3.3 g of H22 (3096 by weight).
The initial mixture was placed in a stirred laboratory vessel, flushed with nitrogen and heated to an internal t~, aLure of 80 C. Then the initiator feed and the regulator feed were started simultaneously and added at a constant rate simultaneously over the course of 3 hours. To complete the polymerization, the poly-meri2~ation 1 , aLuLe of 80 C waa maintained for a further 2 hours. Volatile impurities were removed by ~ L steam distillation, during which 500 g of water distilled out.
The resulting colorless and low-viscosity solution had a solids content of 2096, and the R value of the product (measured at a ~vl-.ellL~ aLion of 1% by weight in water) was 16.4 . The impurities found were 0.0396 of N-vinylpyrrolidone and 2.259~ of pyrrolidone.
Claims (3)
1. A process for the preparation of low molecular weight homo-polymers of N-vinylpyrrolidone by solution polymerization in aqueous medium in the presence of a compound which forms free radicals, wherein the polymerization is carried out in the presence of a polymerization regulator which has a transfer constant Cx greater than 0.01.
2. A process as claimed in claim 1, wherein the polymerization regulator is used in amounts of from 0.1 to 15% by weight based on the amount of monomer.
3. A process as claimed in claim 1, wherein mercapto compounds, dialkyl sulfides and/or diaryl sulfides are added as polymer-ization regulators.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE19533264.4 | 1995-09-08 | ||
| DE1995133264 DE19533264A1 (en) | 1995-09-08 | 1995-09-08 | Process for the preparation of low-pyrrolidone, low molecular weight homopolymers of N-vinylpyrrolidone |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2184837A1 true CA2184837A1 (en) | 1997-03-09 |
Family
ID=7771639
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2184837 Abandoned CA2184837A1 (en) | 1995-09-08 | 1996-09-04 | Preparation of low-pyrrolidone, low molecular weight homopolymers of n-vinylpyrrolidone |
Country Status (4)
| Country | Link |
|---|---|
| EP (1) | EP0761699A2 (en) |
| JP (1) | JPH09110933A (en) |
| CA (1) | CA2184837A1 (en) |
| DE (1) | DE19533264A1 (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US7786233B2 (en) | 2007-01-26 | 2010-08-31 | Nippon Shokubai Co., Ltd. | Polyvinylpyrrolidone powder compositions |
| CN102603949A (en) * | 2011-12-22 | 2012-07-25 | 张家口市珂玛精细化工有限公司 | Method for preparing polyvinylpyrrolidone K30 by using low-purity vinylpyrrolidone |
Families Citing this family (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE19727476A1 (en) * | 1997-06-27 | 1999-01-07 | Basf Ag | Process for the preparation of low molecular weight homopolymers of N-vinylpyrrolidone |
| US6465592B1 (en) | 2000-06-15 | 2002-10-15 | Dai-Ichi Kogyo Seiyaku Co., Ltd. | Process for preparing vinylpyrrolidone polymer |
| JP3773408B2 (en) * | 2000-06-15 | 2006-05-10 | 第一工業製薬株式会社 | Method for producing vinylpyrrolidone polymer |
| JP2001354723A (en) * | 2000-06-15 | 2001-12-25 | Dai Ichi Kogyo Seiyaku Co Ltd | Method for producing highly pure vinyl pyrrolidone polymer |
| JP4578714B2 (en) * | 2001-04-26 | 2010-11-10 | 大阪有機化学工業株式会社 | N-vinyl-2-pyrrolidone-containing resin composition, process for producing the same, and cosmetic comprising the same |
| JP4881518B2 (en) * | 2001-08-01 | 2012-02-22 | 第一工業製薬株式会社 | Method for producing vinyl lactam polymer |
| JP5483793B2 (en) * | 2006-02-09 | 2014-05-07 | 株式会社日本触媒 | Vinylpyrrolidone polymer solution and method for producing the same |
| WO2023099232A1 (en) * | 2021-11-30 | 2023-06-08 | Basf Se | Preparation of n-vinylpyrrolidone polymers, containing less than 0.5 wt% of 2-pyrrolidone |
-
1995
- 1995-09-08 DE DE1995133264 patent/DE19533264A1/en not_active Withdrawn
-
1996
- 1996-08-28 EP EP96113726A patent/EP0761699A2/en not_active Withdrawn
- 1996-09-04 JP JP23444596A patent/JPH09110933A/en not_active Withdrawn
- 1996-09-04 CA CA 2184837 patent/CA2184837A1/en not_active Abandoned
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US7786233B2 (en) | 2007-01-26 | 2010-08-31 | Nippon Shokubai Co., Ltd. | Polyvinylpyrrolidone powder compositions |
| CN102603949A (en) * | 2011-12-22 | 2012-07-25 | 张家口市珂玛精细化工有限公司 | Method for preparing polyvinylpyrrolidone K30 by using low-purity vinylpyrrolidone |
| CN102603949B (en) * | 2011-12-22 | 2014-03-19 | 张家口市珂玛精细化工有限公司 | Method for preparing polyvinylpyrrolidone K30 by using low-purity vinylpyrrolidone |
Also Published As
| Publication number | Publication date |
|---|---|
| EP0761699A2 (en) | 1997-03-12 |
| DE19533264A1 (en) | 1997-03-13 |
| JPH09110933A (en) | 1997-04-28 |
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