JP3033915B2 - Method for producing polymer having thiol group - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing a polymer having a thiol group.

2. Description of the Related Art A technique for controlling a terminal group of a polymer is extremely important from the viewpoint of environmental stability of the polymer and synthesis of a polymer having a controlled structure. Thiol groups are, as is well known,
It has an oxidation-reduction ability, forms a mercaptide with heavy metals, and has a very high reactivity to radicals, so it is introduced into a polymer, that is, both side chains of the polymer, Various attempts have been made at terminal and single terminal introduction. Regarding introduction into one end of the polymer, see JP-A-59-187003 and JP-A-59-187.
004 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 thiolic acid with an alkali or an acid. . However, although this method is effective as a production method, since the reactivity of the thiolic acid used, particularly thioacetic acid, which is advantageously used in the method, is high, a side reaction may be accompanied during the polymerization, and the polymerization conditions may be reduced. There are problems such as limitations and, depending on conditions, corrosion of the reactor becomes a problem.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems when using thiolic acid and to provide a process for producing a polymer having a thiol group in the molecule. .

[0002]

Means for Solving the Problems The present inventors have made intensive studies to solve the above-mentioned problems, and as a result, have found that carboxyl groups of dithiol
Radical polymerization of a radically polymerizable monomer in the presence of an acid monoester , and treatment of the resulting polymer with an alkali or an acid allows a thiol group-containing polymer to be produced without causing side reactions or equipment corrosion. and Heading that coalescence is obtained, and completed the present invention. 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 carboxylate group. Examples of the compound having a thiol group and a thiol carboxylate group in the molecule used herein include a thiol group (SH group) and a thiol carboxylate group (SCOR group, where R is a hydrocarbon group). ). That is, a carboxylic acid monoester of dithiol, a carboxylic acid monoester of trithiol or a carboxylic acid diester is selected.
A compound, no particular restriction on the type of carboxylic acid esters, acetic esters, propionic acid esters,
Valerate, benzoate and the like. Specific examples of the compound include ethanedithiol monoacetate, ethanedithiol monopropionate, ethanedithiol monobenzoate, 1,4-butanedithiol monoacetate, 1,4-butanedithiol monopropionate, 1,4-butanedithiol
Mono benzoate, 1,6-hexanedithiol monoacetate, 1,6-hexanedithiol mono acid esters, 1,6-dithiol mono benzoates, 1,10 decanedithiol monoacetate, 1,10 - decanedithiol mono propionate, 1,10 decanedithiol mono benzoate, 1,2-benzene dithiol monoacetate, 1,2-benzene dithiol mono acid esters, 1,2-benzene dithiol mono benzoate 1,3-benzenedithiol monoacetic acid ester,
Examples thereof include 1,3-benzenedithiol monopropionate, 1,3-benzenedithiol monobenzoate, and the like, and acetate is preferably used because of the ease of decomposition with an alkali or an acid described below. A polymer containing a thiol group is polymerized using the compound,
Although it is obtained by alkali or acid treatment, the compound to be used is appropriately selected depending on the properties of the intended polymer, the purpose of use, the radical polymerizability of the monomer to be polymerized and the like.

The production method of the present invention can be applied without particular limitation as long as it is a monomer capable of radical polymerization, and a polymer having a thiol group can be obtained. Examples of such a monomer include the following monomers. That is, olefins such as ethylene, propylene, 1-butene, and isobutene; vinyl acetates such as vinyl acetate, propionic acid, vinyl pivalate, and vinyl versatate; acrylic acid; methyl acrylate; ethyl acrylate; Acrylates 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, 2-diethylaminoethyl methacrylate and its salts and quaternary salts, methacrylic acid (2-hydroxy )
Methacrylic esters such as dimethylaminopropyl and 3-trimethoxysilylpropyl methacrylate, styrene, p-methylstyrene, α-methylstyrene, chloromethylstyrene, p-styrenesulfonic acid and salts thereof, p-hydroxystyrene and Styrenes such as derivatives, acrylamide, N-methylacrylamide,
Acrylamide derivatives such as N-ethylacrylamide, N, N-dimethylacrylamide, diacetone acrylamide, acrylamidepropanesulfonic acid and its salts, acrylamidopropyldimethylamine and its salts and quaternary salts, N-methylolacrylamide and its derivatives, methacrylamide Methacrylamide derivatives such as N-methylmethacrylamide, N-ethylmethacrylamide, methacrylamidopropanesulfonic acid and its salts, methacrylamidopropyldimethylamine and its salts and quaternary salts, N-methylol methacrylamide and its derivatives, -Vinylpyrrolidone, methyl vinyl ether, ethyl vinyl ether, n-propyl vinyl ether, i-propyl vinyl ether, n-butyl vinyl ether, i- Chill ether, t- butyl ether, dodecyl vinyl ether and stearyl vinyl ether, acrylonitrile, nitriles such as methacrylonitrile, vinyl chloride,
Vinylidene chloride, vinyl fluoride, vinyl halides such as vinylidene fluoride, allyl acetate, allyl chloride, allyl compounds such as allyl alcohol, maleic anhydride, maleic acid and its salts and esters, fumaric acid and its salts and its In addition to esters, itaconic acid and salts and esters thereof, isopropenyl acetate, N-vinylimidazole, etc., macromonomers such as polyoxyalkylene, polyoxyalkylene phosphate, polystyrene, polymethyl methacrylate, polysiloxane and the like. ,
These are used in homopolymerization or copolymerization.

In the synthesis of the polymer having a thiol group according to the present invention, as a first step, a radically polymerizable monomer is radically polymerized in the presence of a compound having a thiol group and a thiol carboxylate group in the molecule. By
A precursor of the polymer is obtained. Here, the addition of the compound having a thiol group and a thiol carboxylate group in the molecule to the polymerization system is performed by introducing the compound into the polymer due to the ease of a chain transfer reaction of the monomer to be polymerized to the compound. The most efficient method is selected. Usually, a method in which both the monomer and the compound are added at once or a method in which the monomer and / or the compound are added continuously or dividedly during the polymerization reaction is employed. . The polymerization is carried out by a usual radical polymerization method, and is carried out by a known system such as a batch system, a semi-batch system, and a continuous system by bulk polymerization, solution polymerization, suspension polymerization or emulsion polymerization. As the radical polymerization initiator, azo compounds, peroxides, hydroperoxides and the like 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, n-propylperoxycarbonate, i-propylperoxycarbonate, potassium persulfate, ammonium persulfate, peroxide Specific examples include hydrogen, t-butyl hydroperoxide, cumene hydroperoxide and the like. Polymerization by light, radiation, or electron beam irradiation can also be used. The polymerization temperature is not particularly limited, but is usually -2.
It is selected in the range of 0 ° C to 150 ° C. Subsequently, the precursor is hydrolyzed to obtain a polymer having a thiol group. The method of hydrolysis is not particularly limited, and hydrolysis or solvolysis using a base or acid in a solvent capable of dissolving or dispersing the precursor is applied. The solvent used is appropriately determined in consideration of the solubility depending on the type of the precursor,
Usually methanol, ethanol, n-propanol, i-
Alcohols such as propanol, tetrahydrofuran,
Dioxane, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, diethylene glycol dimethyl ether, ethers such as diethylene glycol diethyl ether, aromatics such as benzene, toluene, xylene, aliphatic hydrocarbons such as hexane and heptane, water alone or mixed Used as Examples of 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-butylate, lithium methylate and lithium ethylate; mineral acids such as hydrochloric acid and sulfuric acid; benzenesulfonic acid;
Examples include sulfonic acids such as toluenesulfonic acid, and cation and anion exchange resins, ion exchange membranes and the like can also be used. Among them, a method of transesterification using an alkali metal hydroxide or an alcoholate and methanol is often used. The hydrolysis reaction is carried out in a substantially oxygen-free state to prevent oxidation of the generated thiol group, usually in a system replaced with an inert gas such as nitrogen gas or argon gas, and immediately after the reaction is completed. It is preferred to carry out neutralization with an acid. The reaction temperature and the reaction time are not particularly limited, and the reaction is usually carried out at a temperature of from room temperature to 100 ° C for a period of 5 minutes to 10 hours. In order to promote the reaction, the reaction is often carried out while removing generated methyl acetate and the like outside the reaction system.

[0005]

The present invention will be described below in more detail with reference to examples, but the present invention is not limited thereto. In the examples, “%” and “parts” represent “% by weight” and “parts by weight” unless otherwise specified. Example 1 A reactor equipped with a stirrer, a reflux condenser, a nitrogen inlet tube and a thermometer was charged with 2400 g of vinyl acetate monomer and 600 g of methanol, and degassed by bubbling nitrogen gas for 15 minutes. Separately, ethanedithiol monoacetate 0.3
Initial addition liquid of thiol obtained by dissolving 7 g in 50 g of methanol, continuous addition liquid of thiol having a total amount of 100 ml by adding methanol to 30 g of ethanedithiol monoacetate, and 2,2′-azobisisobutyronitrile to 50 g of methanol 1. 81 g of an initiator solution in which 81 g was dissolved was prepared, and the atmosphere was replaced with nitrogen by bubbling nitrogen gas.
The temperature of the reactor was started, and when the internal temperature reached 60 ° C., the initial thiol addition solution and the initiator solution prepared above were added in this order to start polymerization. Immediately, the addition of the continuous addition solution of thiol was started, and polymerization was continued while uniformly adding over 3 hours. After 3 hours, the mixture was cooled to stop the polymerization. At this time, the solid content concentration was 53.0%.
Subsequently, unreacted vinyl acetate monomer was removed while occasionally adding methanol at 30 ° C. under reduced pressure to obtain a methanol solution of polyvinyl acetate (concentration: 60.2%). A part of this methanol solution is taken and the polyvinyl acetate concentration is 4
5%, [NaOH] / [VAc] = 0.05 (molar ratio)
Under a nitrogen atmosphere at 40 ° C. for 2 hours.
After neutralization with acetic acid and Soxhlet washing with methanol for purification, a polyvinyl alcohol-based polymer (hereinafter abbreviated as PVA) was obtained. The degree of saponification of the PVA was 99.3 mol%, and the amount of thiol group was determined by iodine titration, and was 2.25 × 10 ↑-↑ 4 equivalent / P.
VA-g.

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

Example 3 A pressure-resistant polymerization reactor 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 bubbling with nitrogen gas. Separately, ethanedithiol monoacetate 1
A solution prepared by dissolving 2.5 g in 100 ml of methanol was prepared and degassed by bubbling with nitrogen. Ethylene was pressurized to a gauge pressure of 38 kg / cm ↑ 2, and when the internal temperature of the pressure-resistant polymerization reactor reached 55 ° C, continuous addition of the methanol solution of thiol prepared above was started. Internal temperature 6
While maintaining the temperature at 0 ° C., the polymerization was carried out while uniformly adding the thiol solution over 4 hours. The polymerization was stopped by cooling, and the solid content was measured to be 23.3%. After purging ethylene, the polymerization liquid was poured into a large amount of n-hexane to recover a vinyl acetate-ethylene copolymer, and acetone-n-
Reprecipitation purification was performed twice using a hexane system. Stirrer, reflux condenser,
In a reactor equipped with a nitrogen inlet tube and a thermometer, 50 g of the copolymer and 100 g of methanol were weighed, degassed under reduced pressure, and purged with nitrogen. Then, a solution of 0.05 g of NaOH dissolved in 10 g of methanol and purged with nitrogen was added. 30 ° C under nitrogen flow
After stirring for 6 hours, 0.16 g of acetic acid was added to neutralize. The reaction solution is poured into a large amount of water to recover the polymer,
The precipitate was purified twice with acetone-n-hexane. The polymer was subjected to iodine titration with a methanol / water (80/20 weight ratio) system, and the amount of thiol groups was 1.28 × 10 ↑-↑ 4.
Equivalent / 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 bubbling with nitrogen gas. Separately, 14.0 g of thioacetic acid was added to methanol 2
A solution dissolved in 00 ml was prepared and degassed by nitrogen bubbling. 38 kg / cm @ 2 of ethylene at gauge pressure
When the internal temperature of the pressure-resistant polymerization reactor reached 55 ° C., continuous addition of the methanol solution of thiol prepared above was started. While maintaining the internal temperature at 60 ° C., the polymerization was carried out while uniformly adding the thiol solution over 8 hours. However, the solid content concentration was as low as 5%, and only a small amount of the polymer was obtained.

Example 4 In a reactor equipped with a stirrer, a still, a nitrogen inlet tube and a thermometer, 60 g of the copolymer of vinyl acetate and ethylene obtained in Example 3 and 250 g of methanol were weighed and degassed under reduced pressure. After purging with nitrogen, the mixture was heated to 60 ° C. Nitrogen flow 50
g of NaOH was added and stirring was continued while the resulting methyl acetate was flushed out with methanol. After 30 minutes, another 50 g of NaOH was added and stirring continued for 2.5 hours. After completion of the reaction, the mixture was cooled to room temperature, neutralized by adding 180 g of acetic acid, and the content was poured into a large amount of distilled water to recover a polymer. The copolymer was purified by repeating washing with distilled water. The copolymer was treated with n-propanol / water (7
(0/30 weight ratio), the iodine titration revealed that the amount of thiol groups was 2.20 × 10 ↑-↑ 4 equivalents / copolymer-g. H-NMR measurement in d ↓ 6-DMSO showed that the ethylene content was 31 mol% and the degree of saponification of vinyl acetate units was 99.2 mol%.

Example 5 In a reactor equipped with a stirrer, a reflux condenser, a nitrogen inlet and a thermometer, 1000 g of vinyl pivalate monomer and t-
850 g of butanol was charged, and nitrogen gas was bubbled for 15 minutes to degas. Separately, an initial addition solution of thiol in which 0.013 g of hexamethylenedithiol monoacetate was dissolved in 20 g of t-butanol, a continuous addition solution of thiol in which t-butanol was added to 0.60 g of hexamethylenedithiol monoacetate to make the total amount 100 ml, and Initiator solutions were prepared by dissolving 0.43 g of 2,2′-azobisisobutyronitrile in 40 g of methanol, respectively.
Nitrogen was replaced by bubbling of nitrogen gas. The temperature of the reactor was started, and when the internal temperature reached 60 ° C., the initial thiol addition solution and the initiator solution prepared above were added in this order to start polymerization. Immediately, the addition of the continuous addition solution of thiol was started, and polymerization was continued while uniformly adding over 3 hours. After 3 hours, the mixture was cooled to stop the polymerization. At this time, the solid content concentration 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 with an acetone-methanol system for purification. In a reactor equipped with a stirrer, a reflux condenser, a nitrogen inlet tube and a thermometer, 50 g of the copolymer and 50 g of methanol were placed.
After 100 g of tetrahydrofuran was weighed, degassed under reduced pressure and purged with nitrogen, a solution of 0.05 g of NaOH dissolved in 10 g of methanol and purged with nitrogen was added. After stirring was continued at 30 ° C. for 6 hours under a nitrogen flow, 0.16 g of acetic acid was added to neutralize the mixture. The reaction solution was poured into a large amount of water to recover a polymer, which was then reprecipitated and purified twice with an acetone-n-hexane system. The polymer was subjected to iodine titration with an acetone / water (90/10 weight ratio) system, and the amount of thiol groups was 8.40 × 1.
0 ↑-↑ 6 equivalents / polymer-g.

Example 6 In a reactor equipped with a stirrer, a still, a nitrogen inlet tube and a thermometer, 10 g of the polyvinyl pivalate obtained in Example 5 and 90 g of methyl ethyl ketone were weighed, degassed under reduced pressure, and purged with nitrogen. Warmed to ° C. Under a nitrogen flow, an alkali solution prepared by separately dissolving 5.3 g of potassium hydroxide in 16 g of methanol and replacing with nitrogen was added, and the mixture was reacted at 60 ° C. for 2 hours. After completion of the reaction, 6.8 g of acetic acid was added for neutralization, and the content was 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 saponification degree of the PVA is 9
9.2 mol%, and the amount of thiol groups was determined by iodine titration. As a result, 2.31 × 10 ↑-↑ 5 equivalent / PVA-
g.

Example 7 1200 g of a styrene 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, 0.10 g of ethanedithiol monoacetate was dissolved in 50 g of toluene, and an initial addition solution of thiol. Toluene was added to 24.6 g of ethanedithiol monoacetate, and the total amount was 100 parts.
ml of thiol and 10 g of toluene
Were prepared by dissolving 3.0 g of 2,2'-azobisisobutyronitrile in each of the above, and nitrogen was replaced by bubbling with nitrogen gas. When the temperature of the reactor was raised and the internal temperature reached 70 ° C., the initial thiol addition solution and the initiator solution prepared above were added in this order to start polymerization. Immediately after the addition of the continuous addition solution of thiol, 12
The polymerization was continued with uniform addition over time. After 12 hours, the system was cooled to stop the polymerization. At this time, the solid content concentration was 47.0%. Subsequently, the polymerization solution was poured into a large amount of methanol to recover the polymer, and the reprecipitation purification was repeated three times with an acetone-methanol system. 50 g of the polymer, 20 g of methanol and 130 g of tetrahydrofuran were weighed and placed in a reactor equipped with a stirrer, a reflux condenser, a nitrogen inlet tube, and a thermometer, degassed under reduced pressure, and purged with nitrogen.
A solution obtained by dissolving 0.05 g of OH in 10 g of methanol and purging with nitrogen was added. After stirring was continued at 30 ° C. for 6 hours under a nitrogen flow, 0.16 g of acetic acid was added to neutralize the mixture. The reaction solution was poured into a large amount of water to recover a polymer, which was then reprecipitated twice with an acetone-methanol system. The polymer was subjected to iodine titration with an acetone / water (90/10 weight ratio) system, and the amount of thiol group was found to be 1.03 × 10 ↑-↑ 4 equivalent / polymer-g.
Met.

Example 8 A reactor equipped with a stirrer, a reflux condenser, a nitrogen inlet tube and a thermometer was charged with 2900 g of methyl methacrylate monomer, and degassed by bubbling nitrogen gas for 15 minutes. Separately, 1.71 g of m-dithiolbenzene monoacetate
Was added to 50 g of toluene, and an initial addition solution of thiol, m
-A continuous addition solution of thiol having a total volume of 100 ml by adding toluene to 40.0 g of dithiolbenzene monoacetate, and an initiator solution obtained by dissolving 1.80 g of 2,2'-azobis (cyclohexane-1-carbonitrile) in 10 g of toluene Were respectively prepared, and nitrogen was replaced by bubbling of nitrogen gas. The temperature of the reactor was raised and the internal temperature was 9
When the temperature reached 0 ° C., the above-prepared initial solution of thiol and the initiator solution were added in this order, and polymerization was started.
Immediately, the addition of the continuous addition solution of thiol was started, and polymerization was continued while uniformly adding over 4 hours. After 4 hours, the mixture was cooled to stop the polymerization. The solid concentration at this time is 6
3.0%. Subsequently, the polymerization liquid was poured into a large amount of n-hexane to recover the polymer, and reprecipitation purification was repeated three times with 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, methanol 50 g and tetrahydrofuran 10
0 g was weighed, degassed under reduced pressure, and purged with nitrogen.
A solution obtained by dissolving 0.05 g in 10 g of methanol and purging with nitrogen was added. After stirring was continued at 30 ° C. for 6 hours under a nitrogen flow, 0.16 g of acetic acid was added to neutralize the mixture. The reaction solution was poured into a large amount of water to recover a polymer, which was then reprecipitated and purified twice with an acetone-n-hexane system. The polymer was dissolved in acetone / water (9
As a result of iodine titration using a (0/10 weight ratio) system, the amount of thiol groups was 1.15 × 10 ↑-↑ 4 equivalent / polymer-g.

Example 9 A reactor equipped with a stirrer, a reflux condenser, a nitrogen inlet tube and a thermometer was charged with 2900 g of ethyl acrylate monomer, 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 having a total volume of 100 ml by adding toluene to 14.0 g of m-dithiolbenzene monoacetate, and 2 additions to 10 g of toluene. , 2'-Azobis (cyclohexane-1-carbonitrile) was prepared in each of which an initiator solution was dissolved, and nitrogen was replaced by bubbling with nitrogen gas. Start raising the temperature of the reactor.
Then, the above-prepared initial solution of thiol and the initiator solution were added in this order to start polymerization. Immediately, the addition of the thiol continuous addition liquid was started, and polymerization was continued while uniformly adding over 5 hours. After 5 hours, the mixture was cooled to stop the polymerization. The solid content at this time is 74.
It was 0%. Subsequently, the polymerization liquid was poured into a large amount of n-hexane to recover the polymer, and reprecipitation purification was repeated three times with 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 and a thermometer.
And methanol 20g and tetrahydrofuran 100g
After degassing under reduced pressure and replacing with nitrogen, NaOH 0.0
A solution obtained by dissolving 5 g in 10 g of methanol and purging with nitrogen was added. After stirring was continued at 30 ° C. for 6 hours under a nitrogen flow, 0.16 g of acetic acid was added to neutralize the mixture. The reaction solution was poured into a large amount of water to recover a polymer, which was then reprecipitated and purified twice with an acetone-n-hexane system. The polymer was dissolved in acetone / water (90/1
(0 weight ratio) system, the thiol group content was 3.45 × 10 ↑-↑ 5 equivalents / polymer-g.

Example 10 A reactor equipped with a stirrer, a reflux condenser, a nitrogen inlet tube and a thermometer was charged with 290 g of acrylic acid monomer and 10.8 g of ethanedithiol monoacetate, and nitrogen gas was added to the reactor.
Degas by bubbling for 5 minutes. Separately, acrylic acid 10g
Was prepared by dissolving 0.30 g of 2,2'-azobisisobutyronitrile in each of the above, and nitrogen was replaced by bubbling with nitrogen gas. The temperature of the reactor was increased, and when the internal temperature reached 60 ° C., the above-prepared initiator solution was added to initiate polymerization. After 2 hours, the system was cooled to stop the polymerization, and the solid content at this time was 37.0%. Subsequently, the polymerization liquid was put into ether to recover the polymer, and reprecipitation purification was repeated three times with a methanol-ether system. In a reactor equipped with a stirrer, a reflux condenser, a nitrogen inlet tube and a thermometer, 50 g of the polymer and 100 g of methanol were weighed, degassed under reduced pressure, and purged with nitrogen.
ml was added. After stirring was continued at 30 ° C. for 6 hours under a nitrogen flow, the reaction solution was poured into a large amount of ether to recover a polymer, which was then reprecipitated twice with a methanol-ether system. When the polymer was subjected to iodine titration, the amount of thiol groups was 9.
76 × 10 ↑-↑ 5 equivalents / polymer-g.

[0016]

According to the present invention, the carboxyl group of dithiol is
Acid monoester, trithiol carboxylic acid monoester
Selected from carboxylic diesters of thiol and trithiol
The radically polymerizable monomers and radical polymerization the presence of a compound having a thiol group and a thiol carboxylic acid ester group in the molecule, the resulting polymer containing a thiol group by treatment with alkali or acid A polymer can be obtained efficiently. It is 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 thiolcarboxylic 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, a radical polymerizable monomer in the presence of the polymer is radically polymerized. By polymerizing, a block copolymer or a graft copolymer composed of a combination of various polymers can be synthesized, and is extremely useful as a dispersion stabilizer during heterogeneous polymerization.

Claims (2)

(57) [Claims] 1. A carboxylic acid monoester of dithiol,
Carboxylic acid monoesters and trithiols of trithiols
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 a molecule selected from carboxylic acid diesters of cellulose, and treating the obtained polymer with an alkali or an acid A method for producing a polymer having a thiol group. 2. A compound having a thiol group and a thiol carboxylic acid ester groups in the molecule, preparation of the polymer of claim 1 wherein the monocarboxylic acid esters of dithiols.