JPH04323203A - Production of polymer having thiol group - Google Patents

Abstract

PURPOSE:To obtain the subject polymer in high efficiency without causing side-reaction and corrosion of apparatus by radical-polymerizing a radical- polymerizable monomer in the presence of a compound having thiol group and thiolcarboxylic acid ester group in the molecule and treating the polymerized product with an alkali or an acid. CONSTITUTION:The objective polymer having thiol group in the molecule (e.g. polyvinyl alcohol containing thiol group) can be produced in high efficiently by radical-polymerizing a radical-polymerizable monomer (e.g. vinyl acetate) in the presence of a compound having thiol group and thiolcarboxylic acid ester group in the molecule (e.g. ethanedithiol monoacetate) using a radical polymerization initiator (e.g. 2,2,-azobisisobutyronitrile) in a solvent (e.g. methanol) at 60 deg.C, cooling the reaction mixture and hydrolyzing the produced polymer by treating with an alkali or an acid.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing polymers containing thiol groups.

BACKGROUND OF THE INVENTION Techniques for controlling the terminal groups of polymers are extremely important from the viewpoint of the environmental stability of polymers and the synthesis of polymers with controlled structures. As is well known, the thiol group
It is a highly active functional group that has oxidation-reduction ability, forms mercaptides with heavy metals, and has extremely high reactivity toward radicals. Various attempts have been made to introduce it into the end and one end. Regarding introduction into the ends of polymer pieces, see Japanese Patent Application Laid-open No. 59-187003 and Japanese Patent Application Laid-open No. 59-1870.
04 and JP-A-59-187005 disclose a method of obtaining a polymer having a thiol group at one end by treating a polymer obtained by radical polymerization in the presence of thiol acid with an alkali or acid. . However, although this method is effective as a production method, due to the high reactivity of the thiol acids used, especially thioacetic acid, which is advantageously used in this method, side reactions may occur during polymerization and the polymerization conditions are It has problems such as limitations and corrosion of the reactor depending on the conditions.

[Problems to be Solved by the Invention] An object of the present invention is to solve the above-mentioned problems when using thiol acid and to provide a method for producing a polymer having a thiol group in the molecule. .

0002

[Means for Solving the Problems] As a result of intensive studies aimed at solving the above problems, the present inventors have developed a monomer capable of radical polymerization in the presence of a compound having a thiol group and a thiol carboxylic acid ester group in the molecule. discovered that by radical polymerizing and treating the resulting polymer with an alkali or acid, a polymer having thiol groups could be obtained without causing side reactions or corrosion of equipment, and the present invention was completed. This is what I did. A feature of the method for producing a polymer of the present invention is that radical polymerization is carried out in the presence of a compound having a thiol group and a thiol carboxylic acid ester group. The compounds used here that have a thiol group and a thiol carboxylic acid ester group in one molecule include a thiol group (SH group) and a thiol carboxylic acid ester group (SCOR group, where R is a hydrocarbon group). It is a compound having the following. In other words, compounds typified by carboxylic acid monoesters of dithiol, carboxylic acid monoesters or carboxylic acid diesters of trithiol, etc. There are no particular restrictions on the type of carboxylic acid ester, and there are no particular restrictions on the type of carboxylic acid ester, such as acetate ester, propionate ester, valerate ester, etc. ,
Benzoic acid esters, etc. Specific examples of the compounds include ethanedithiol monoacetate, ethanedithiol monopropionate, ethanedithiol monobenzoate, 1,4-butanedithiol monoacetate, 1,4-butanedithiol monopropionate, 1,4-butanedithiol benzoate, 1,6-hexanedithiol monoacetate, 1,
6-hexanedithiol monopropionic acid ester, 1
, 6-hexanedithiol monobenzoic acid ester, 1,
10-decanedithiol monoacetate, 1,10-
Decanedithiol monopropionate, 1,10
-decanedithiol benzoate, 1,2-benzenedithiol monoacetate, 1,2-benzenedithiol monopropionate 1,2-benzenedithiol benzoate, 1,3-benzenedithiol monoacetate, 1,3 -benzenedithiol monopropionic acid ester, 1,3-benzenedithiol monobenzoic acid ester, etc., and acetic acid ester is preferably used because of its ease of decomposition with an alkali or acid as described below. A polymer containing a thiol group can be obtained by polymerizing the compound and then treating it with an alkali or acid. It is selected appropriately depending on gender, etc.

The production method of the present invention can be applied without any particular restriction as long as it is a monomer that can be radically polymerized, and a polymer having a thiol group can be obtained. Examples of such monomers include the following monomers. That is, olefins such as ethylene, propylene, 1-butene, and isobutene, vinyl esters such as vinyl acetate, propionic acid, vinyl pivalate, and vinyl versatate, acrylic acid, methyl acrylate, ethyl acrylate, and n-acrylate. Acrylic esters such as butyl, 2-ethylhexyl acrylate, dodecyl acrylate, methacrylic acid and its salts, methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, i-propyl methacrylate, n-butyl methacrylate, i-Butyl methacrylate, t-butyl methacrylate, 2-ethylhexyl methacrylate, dodecyl methacrylate, octadecyl methacrylate, 2-hydroxyethyl methacrylate, 2-dimethylaminoethyl methacrylate and its salts and quaternary salts, methacrylic acid 2-diethylaminoethyl and its salts and quaternary salts, methacrylic acid esters such as (2-hydroxy)dimethylaminopropyl methacrylate and 3-trimethoxysilylpropyl methacrylate, styrene, p-methylstyrene, α-methylstyrene, Chloromethylstyrene, p-styrenesulfonic acid and its salts,
Styrenes such as p-hydroxystyrene and its derivatives, acrylamide, N-methylacrylamide, N-
Acrylamide derivatives such as ethyl acrylamide, N,N-dimethylacrylamide, diacetone acrylamide, acrylamide propanesulfonic acid and its salts, acrylamide propyl dimethylamine and its salts and quaternary salts, N-methylolacrylamide and its derivatives, methacrylamide, N - methylmethacrylamide,
Methacrylamide derivatives such as N-ethylmethacrylamide, methacrylamidepropanesulfonic acid and its salts, methacrylamidepropyldimethylamine and its salts and quaternary salts, N-methylolmethacrylamide and its derivatives, N-vinylpyrrolidone, methyl vinyl ether, Vinyl ethers such as ethyl vinyl ether, n-propyl vinyl ether, i-propyl vinyl ether, n-butyl vinyl ether, i-butyl vinyl ether, t-butyl vinyl ether, dodecyl vinyl ether, stearyl vinyl ether, nitriles such as acrylonitrile and methacrylonitrile, vinyl chloride , vinyl halides such as vinylidene chloride, vinyl fluoride, vinylidene fluoride, allyl compounds such as allyl acetate, allyl chloride, and allyl alcohol, maleic anhydride, maleic acid and its salts and esters, fumaric acid and its salts, its esters, itaconic acid and its salts and its esters;
In addition to isopropenyl acetate, N-vinylimidazole, etc., macromonomers such as polyoxyalkylene, polyoxyalkylene phosphate, polystyrene, polymethyl methacrylate, and polysiloxane are included, and these are used in homopolymerization or copolymerization. Ru.

[0004] The synthesis of the polymer having a thiol group of the present invention involves, as a first step, radical polymerization of a radically polymerizable monomer in the presence of a compound having a thiol group and a thiol carboxylic acid ester group in the molecule. According to
A precursor of the polymer is obtained. Here, the addition of a compound having a thiol group and a thiol carboxylic acid ester group in the molecule to the polymerization system is based on the ease with which a chain transfer reaction of the monomer to be polymerized to the compound occurs. The most efficient method is selected, and usually a method is adopted in which both the monomer and the compound are added at once, or the monomer and/or the compound are added continuously or in portions during the polymerization reaction. . Polymerization is carried out by a conventional radical polymerization method, and is carried out by bulk polymerization, solution polymerization, suspension polymerization, or emulsion polymerization in a known manner such as a batch, semi-batch, or continuous method. As the radical polymerization initiator, azo compounds, peroxides, hydroperoxides, etc. are used, and 2,2'-azobisisobutyronitrile, 2,2'-azobis(4-methoxy-2,4
'-dimethylvaleronitrile), 1,1'-azobis(
cyclohexane-1-carbonitrile), 2,2'-azobis(2,4-dimethylvaleronitrile), 2,2'
-Azobis(2-amidinopropane) hydrochloride, 2,2'
-Azobis[2-(2-imidazolin-2-yl)propane], dimethyl 2,2'-azobis(2-methylpropionate), benzoyl peroxide, lauroyl peroxide,
Specific examples include n-propyl peroxycarbonate, i-propyl peroxycarbonate, potassium persulfate, ammonium persulfate, hydrogen peroxide, t-butyl hydroperoxide, and cumene hydroperoxide. Polymerization by light, radiation, or electron beam irradiation can also be used. There are no particular restrictions on the polymerization temperature, but it is usually -20°C.
to 150°C. Subsequently, the precursor is hydrolyzed to obtain a polymer having thiol groups. There are no particular limitations on the method of hydrolysis, and hydrolysis or solvolysis using a base or acid in a solvent that can dissolve or disperse the precursor is applicable. The solvent to be used is appropriately determined depending on the type of precursor, taking into account its solubility, but usually includes alcohols such as methanol, ethanol, n-propanol, and i-propanol, tetrahydrofuran, dioxane, ethylene glycol dimethyl ether, Ethers such as ethylene glycol diethyl ether, diethylene glycol dimethyl ether, and diethylene glycol diethyl ether, aromatic systems such as benzene, toluene, and xylene, aliphatic hydrocarbon systems such as hexane and heptane, and water are used alone or in combination. In addition, bases and acids include hydroxides of alkali metals and alkaline earth metals such as sodium hydroxide, potassium hydroxide, lithium hydroxide, and calcium hydroxide, sodium methylate, sodium ethylate, potassium methylate, and potassium ethylate. , alkali metal alcoholates such as potassium t-butyrate, lithium methylate, and lithium ethylate, mineral acids such as hydrochloric acid and sulfuric acid, and sulfonic acids such as benzenesulfonic acid and p-toluenesulfonic acid. Ion exchange resins, ion exchange membranes, etc. can also be used. Among these, a method of transesterification using an alkali metal hydroxide or alcoholate and methanol is often used. The hydrolysis reaction is carried out in a substantially oxygen-free environment, usually in a system purged with an inert gas such as nitrogen gas or argon gas, to prevent oxidation of the thiol groups produced, and immediately after the reaction is completed. Preferably, neutralization is carried out with an acid. There are no particular restrictions on the reaction temperature and reaction time, and the reaction is usually carried out at a temperature from room temperature to 100°C for a period of 5 minutes to 10 hours. Furthermore, in order to promote the reaction, the reaction is often carried out while removing the produced methyl acetate and the like from the reaction system.

[0005]

[Examples] The present invention will be explained in more detail below with reference to Examples, but the present invention is not limited thereto in any way. Note that "%" and "parts" in the examples represent "% by weight" and "parts by weight" unless otherwise specified. Example 1 2400 g of vinyl acetate monomer and 600 g of methanol were charged into a reactor equipped with a stirrer, a reflux condenser, a nitrogen inlet tube, and a thermometer, and degassed by bubbling nitrogen gas for 15 minutes. Separately, ethanedithiol monoacetate 0.3
An initial addition solution of thiol in which 7 g of thiol was dissolved in 50 g of methanol, a continuous addition solution of thiol in which methanol was added to 30 g of ethanedithiol monoacetate to make a total volume of 100 ml, and 1. Initiator solutions in which 81 g of each initiator were dissolved were prepared and replaced with nitrogen by bubbling nitrogen gas. The temperature of the reactor was started to rise, and when the internal temperature reached 60° C., the thiol initial addition solution and initiator solution prepared above were added in this order to start polymerization. Immediately, continuous addition of the thiol solution was started, and the polymerization was continued while uniformly adding the thiol over a period of 3 hours. After 3 hours, the mixture was cooled to stop polymerization. The solid content concentration at this time was 53.0%. Subsequently, unreacted vinyl acetate monomer was removed under reduced pressure at 30° C. while occasionally adding methanol, to obtain a methanol solution of polyvinyl acetate (concentration 60.2%). Take a part of this methanol solution and add polyvinyl acetate concentration 4.
5%, [NaOH]/[VAc] = 0.05 (molar ratio)
Saponification was carried out at 40° C. for 2 hours under nitrogen atmosphere under the following conditions. A polyvinyl alcohol polymer (hereinafter abbreviated as PVA) was obtained by neutralizing with acetic acid and purifying it by Soxhlet washing with methanol. The degree of saponification of the PVA was 99.3 mol%, and the amount of thiol groups determined by iodometric titration was 2.25 x 10↑-↑4 equivalents/P.
It was VA-g.

Example 2 30 g of methanol solution of polyvinyl acetate obtained in Example 1
and degassed by bubbling nitrogen gas, then 5 m of 25% ammonia water degassed by bubbling nitrogen gas.
1 was added thereto, and the mixture was stirred at 25° C. for 30 minutes under a nitrogen atmosphere. Thereafter, the polyvinyl acetate solution was poured into water to recover the polymer, which was purified by repeating reprecipitation twice in an acetone-water system. The polyvinyl acetate was mixed with methanol/water (80/
As a result of iodometric titration using a 20 weight ratio) system, the amount of thiol groups was 1.35 x 10↑-↑4 equivalents/PVA-g.

Example 3 1651 g of vinyl acetate, 369 g of methanol and 0.512 g of 2,2-azobisisobutyronitrile were charged into a pressure-resistant polymerization vessel equipped with a stirrer, and degassed by nitrogen gas bubbling. Separately, ethanedithiol monoacetate 1
A solution of 2.5 g dissolved in 100 ml of methanol was prepared and degassed by nitrogen bubbling. Ethylene was pressurized to a gauge pressure of 38 kg/cm↑2, and when the internal temperature of the pressure polymerization vessel reached 55° C., continuous addition of the methanol solution of thiol prepared above was started. internal temperature 6
Polymerization was carried out while maintaining the temperature at 0° C. and uniformly adding the thiol solution over a period of 4 hours. The polymerization was stopped by cooling, and the solid content was measured and found to be 23.3%. After purging the polymerization solution of ethylene, it was poured into a large amount of n-hexane to recover the vinyl acetate-ethylene copolymer, and the acetone-n-hexane copolymer was recovered.
It was purified by reprecipitation twice using a hexane system. Stirrer, reflux condenser,
50 g of the copolymer and 100 g of methanol were weighed into a reactor equipped with a nitrogen inlet tube and a thermometer, degassed under reduced pressure, and replaced with nitrogen. A solution of 0.05 g of NaOH dissolved in 10 g of methanol and replaced with nitrogen was added thereto. Under nitrogen flow, 30℃
After continued stirring for 6 hours, 0.16 g of acetic acid was added to neutralize. Pour the reaction solution into a large amount of water and collect the polymer.
It was purified by reprecipitation twice using an acetone-n-hexane system. When the polymer was subjected to iodometric titration with a methanol/water (80/20 weight ratio) system, the amount of thiol groups was 1.28x10↑-↑4
equivalent weight/copolymer-g.

Comparative Example 1 A pressure-resistant polymerization vessel equipped with a stirrer was charged with 1651 g of vinyl acetate, 369 g of methanol, and 0.512 g of 2,2-azobisisobutyronitrile, and degassed by nitrogen gas bubbling. Separately, ethanedithiol monoacetate 1
A solution of 4.0 g dissolved in 200 ml of methanol was prepared and degassed by nitrogen bubbling. Ethylene was pressurized to a gauge pressure of 38 kg/cm↑2, and when the internal temperature of the pressure polymerization vessel reached 55° C., continuous addition of the methanol solution of thiol prepared above was started. internal temperature 6
Polymerization was carried out while maintaining the temperature at 0° C. and uniformly adding a thiol solution over a period of 8 hours, but the solid content concentration was as low as 5% and only a small amount of polymer was obtained.

Example 4 60 g of the copolymer of vinyl acetate and ethylene obtained in Example 3 and 250 g of methanol were weighed into a reactor equipped with a stirrer, a distiller, a nitrogen inlet pipe, and a thermometer, and degassed under reduced pressure. After replacing the atmosphere with nitrogen, it was heated to 60°C. 50g nitrogen flow
of NaOH was added, and stirring was continued while the generated methyl acetate was flowed out together with methanol. After 30 minutes, another 50 g of NaOH was added and stirring continued for 2.5 hours. After the reaction was completed, the mixture was cooled to room temperature, neutralized by adding 180 g of acetic acid, and the contents were poured into a large amount of distilled water to recover the polymer. The copolymer was purified by repeated washing with distilled water. The copolymer was mixed with n-propanol/water (70
/30 weight ratio) system, the amount of thiol groups was 2.20 x 10↑-↑4 equivalents/g of copolymer. Further, when H-NMR was measured in d↓6-DMSO, the ethylene content was 31 mol% and the degree of saponification of vinyl acetate units was 99.2 mol%.

Example 5 1000 g of vinyl pivalate monomer and t-
850 g of butanol was charged and degassed by bubbling nitrogen gas for 15 minutes. Separately, a thiol initial addition solution in which 0.013 g of hexamethylene dithiol monoacetate was dissolved in 20 g of t-butanol, a continuous thiol addition solution in which t-butanol was added to 0.60 g of hexamethylene dithiol monoacetate to make a total volume of 100 ml, and Each initiator solution was prepared by dissolving 0.43 g of 2,2'-azobisisobutyronitrile in 40 g of methanol,
Nitrogen replacement was performed by bubbling nitrogen gas. The temperature of the reactor was started to rise, and when the internal temperature reached 60° C., the thiol initial addition solution and initiator solution prepared above were added in this order to start polymerization. Immediately, continuous addition of the thiol solution was started, and the polymerization was continued while uniformly adding the thiol over a period of 3 hours. After 3 hours, the mixture was cooled to stop polymerization. The solid content concentration at this time was 29.0%. Subsequently, the polymerization solution was poured into a large amount of methanol to recover the polymer, and the reprecipitation operation was repeated twice in an acetone-methanol system for purification. 50 g of the copolymer and 50 g of methanol were placed in a reactor equipped with a stirrer, a reflux condenser, a nitrogen inlet tube, and a thermometer.
Weighed out 100g of tetrahydrofuran, degassed it under reduced pressure and replaced it with nitrogen, then added 0.05g of NaOH to 11g of methanol.
A solution dissolved in 0 g and replaced with nitrogen was added. under nitrogen flow,
After continuing stirring at 30° C. for 6 hours, 0.16 g of acetic acid was added to neutralize. The reaction solution was poured into a large amount of water to recover the polymer, which was purified by reprecipitation twice using an acetone-n-hexane system. When the polymer was subjected to iodometric titration using an acetone/water (90/10 weight ratio) system, the amount of thiol groups was 8.40x10↑
-↑6 equivalents/g of polymer.

Example 6 10 g of vinyl pivalate and 90 g of methyl ethyl ketone obtained in Example 5 were weighed into a reactor equipped with a stirrer, a distiller, a nitrogen inlet tube, and a thermometer, degassed under reduced pressure, and replaced with nitrogen. Warmed to ℃. Under nitrogen flow, an alkaline solution prepared by separately dissolving 5.3 g of potassium hydroxide in 16 g of methanol and replacing the mixture with nitrogen was added, and the mixture was reacted at 60° C. for 2 hours. After the reaction was completed, 6.8 g of acetic acid was added to neutralize, and the contents were pulverized in a large amount of methanol containing a small amount of acetic acid, and purified by Soxhlet washing with methanol to obtain PVA. The degree of saponification of the PVA is 99.
The amount of thiol groups was determined by iodometric titration and was 2.31×10↑−↑5 equivalents/PVA-g.

Example 7 A reactor equipped with a stirrer, a reflux condenser, a nitrogen inlet tube and a thermometer was charged with 1200 g of styrene monomer, and degassed by bubbling nitrogen gas for 15 minutes. Separately, prepare the initial thiol addition solution by dissolving 0.10 g of ethanedithiol monoacetate in 50 g of toluene, add toluene to 24.6 g of ethanedithiol monoacetate, and bring the total amount to 100 g.
ml continuous addition of thiol and 10 g of toluene
An initiator solution was prepared by dissolving 3.0 g of 2,2'-azobisisobutyronitrile in each solution, and the mixture was replaced with nitrogen by bubbling nitrogen gas. The temperature of the reactor was started to rise, and when the internal temperature reached 70° C., the thiol initial addition solution and initiator solution prepared above were added in this order to start polymerization. Immediately start adding thiol continuously and add 12
Polymerization was continued with uniform addition over time. After 12 hours, the mixture was cooled to stop polymerization. The solid content concentration at this time was 47.0%. Subsequently, the polymerization solution was poured into a large amount of methanol to recover the polymer, and reprecipitation purification was repeated three times using an acetone-methanol system. 50 g of the polymer, 20 g of methanol, and 130 g of tetrahydrofuran were weighed into a reactor equipped with a stirrer, a reflux condenser, a nitrogen introduction tube, and a thermometer, degassed under reduced pressure, and replaced with nitrogen.
A solution in which 0.05 g of H was dissolved in 10 g of methanol and replaced with nitrogen was added. After continuing stirring at 30° C. for 6 hours under a nitrogen flow, 0.16 g of acetic acid was added to neutralize. The reaction solution was poured into a large amount of water to recover the polymer, which was purified by reprecipitation twice in an acetone-methanol system. The polymer was dissolved in acetone/water (9
When iodine titration was performed using a 0/10 weight ratio) system, the amount of thiol groups was 1.03 x 10↑-↑4 equivalents/g of polymer.

Example 8 2900 g of methyl methacrylate monomer was charged into a reactor equipped with a stirrer, a reflux condenser, a nitrogen inlet tube and a thermometer, and degassed by bubbling nitrogen gas for 15 minutes. Separately, prepare a thiol initial addition solution prepared by dissolving 1.71 g of m-dithiolbenzene monoacetate in 50 g of toluene, m-
A continuous addition solution of thiol prepared by adding toluene to 40.0 g of dithiolbenzene monoacetate to make a total volume of 100 ml and an initiator solution prepared by dissolving 1.80 g of 2,2'-azobis(cyclohexane-1-carbonitrile) in 10 g of toluene were added. Each was prepared and replaced with nitrogen by bubbling nitrogen gas. Start raising the temperature of the reactor, and the internal temperature reaches 90
When the temperature reached .degree. C., the thiol initial addition solution and initiator solution prepared above were added in this order to initiate polymerization. Immediately, continuous addition of thiol was started, and polymerization was continued while uniformly adding over 4 hours. After 4 hours, the mixture was cooled to stop polymerization. The solid content concentration at this time is 6
It was 3.0%. Subsequently, the polymer solution was poured into a large amount of n-hexane to recover the polymer, and reprecipitation purification was repeated three times using an acetone-n-hexane system. Stirrer, reflux condenser,
The polymer 5 was placed in a reactor equipped with a nitrogen inlet tube and a thermometer.
0 g and methanol 50 g and tetrahydrofuran 10
After weighing out 0 g, degassing it under reduced pressure and replacing it with nitrogen, NaOH0
．． A solution in which 05 g of 0.05 g was dissolved in 10 g of methanol and replaced with nitrogen was added. After continuing stirring at 30° C. for 6 hours under a nitrogen flow, 0.16 g of acetic acid was added to neutralize. The reaction solution was poured into a large amount of water to recover the polymer, which was purified by reprecipitation twice using an acetone-n-hexane system. The polymer was mixed with acetone/water (90%
/10 weight ratio) system, the amount of thiol groups was 1.15 x 10↑-↑4 equivalents/g of polymer.

Example 9 2900 g of ethyl acrylate monomer was charged into a reactor equipped with a stirrer, a reflux condenser, a nitrogen inlet tube and a thermometer, and degassed by bubbling nitrogen gas for 15 minutes. Separately,
An initial addition solution of thiol in which 0.61 g of m-dithiolbenzene monoacetate was dissolved in 50 g of toluene, a continuous addition solution of thiol in which toluene was added to 14.0 g of m-dithiolbenzene monoacetate to make a total volume of 100 ml, and a solution of 2 to 10 g of toluene were added. , 0.40 g of 2'-azobis(cyclohexane-1-carbonitrile) were prepared, and the solution was replaced with nitrogen by bubbling nitrogen gas. Start raising the temperature of the reactor and the internal temperature is 90℃
At this point, the thiol initial addition solution prepared above and the initiator solution were added in this order to initiate polymerization. Immediately, continuous addition of the thiol solution was started, and the polymerization was continued while uniformly adding the thiol over a period of 5 hours. After 5 hours, the mixture was cooled to stop polymerization. The solid content concentration at this time was 74.
It was 0%. Subsequently, the polymer solution was poured into a large amount of n-hexane to recover the polymer, and reprecipitation purification was repeated three times using an acetone-n-hexane system. 50 g of the polymer was placed in a reactor equipped with a stirrer, a reflux condenser, a nitrogen inlet tube, and a thermometer.
and 20 g of methanol and 100 g of tetrahydrofuran
After measuring and degassing under reduced pressure and replacing with nitrogen, NaOH0.0
A solution of 5 g dissolved in 10 g methanol and replaced with nitrogen was added. After continuing stirring at 30° C. for 6 hours under a nitrogen flow, 0.16 g of acetic acid was added to neutralize. The reaction solution was poured into a large amount of water to recover the polymer, which was purified by reprecipitation twice using an acetone-n-hexane system. The polymer was mixed with acetone/water (90/1
0 weight ratio) system, the amount of thiol groups was 3.45 x 10↑-↑5 equivalents/g of polymer.

Example 10 290 g of acrylic acid monomer and 10.8 g of ethanedithiol monoacetate were charged into a reactor equipped with a stirrer, a reflux condenser, a nitrogen inlet tube, and a thermometer, and 1 g of nitrogen gas was charged.
It was degassed by bubbling for 5 minutes. Separately, 10g of acrylic acid
An initiator solution was prepared by dissolving 0.30 g of 2,2'-azobisisobutyronitrile in each solution, and the mixture was replaced with nitrogen by bubbling nitrogen gas. Raising the temperature of the reactor was started, and when the internal temperature reached 60° C., the initiator solution prepared above was added to start polymerization. After 2 hours, the polymerization was stopped by cooling, and the solid content concentration at this time was 37.0%. Subsequently, the polymerization solution was poured into ether to recover the polymer, and reprecipitation purification was repeated three times in a methanol-ether system. 50 g of the polymer and 100 g of methanol were weighed into a reactor equipped with a stirrer, a reflux condenser, a nitrogen inlet tube, and a thermometer, degassed under reduced pressure, and replaced with nitrogen.
1 was added. After continuing to stir at 30° C. for 6 hours under a nitrogen stream, the reaction solution was poured into a large amount of ether to recover the polymer, which was purified by reprecipitation twice in a methanol-ether system. When the polymer was subjected to iodometric titration, the amount of thiol groups was 9.7.
It was 6x10↑-↑5 equivalents/g of polymer.

[0016]

According to the present invention, a radically polymerizable monomer is radically polymerized in the presence of a compound having a thiol group and a thiolcarboxylic acid ester group in the molecule, and the resulting polymer is treated with an alkali or acid. By the treatment, a polymer containing a thiol group can be efficiently obtained. It is also clear from the above Examples and Comparative Examples that the production method of the present invention using the compound is superior to the method using thiol carboxylic acid. The polymer having a thiol group in the molecule obtained in the present invention is a highly reactive polymer material reflecting the high reactivity of the thiol group. For example, in the presence of the polymer, a monomer capable of radical polymerization is Through polymerization, block copolymers or graft copolymers consisting of combinations of various polymers can be synthesized, and are extremely useful as dispersion stabilizers during heterogeneous polymerization.

Claims (2)

[Claims] [Claim 1] A monomer capable of radical polymerization is subjected to radical polymerization in the presence of a compound having a thiol group and a thiol carboxylic acid ester group in the molecule, and the resulting polymer is treated with an alkali or an acid. A method for producing a polymer having a thiol group. 2. The method for producing a polymer according to claim 1, wherein the compound having a thiol group and a thiolcarboxylic acid ester group in the molecule is a dithiol monocarboxylic acid ester.