JPH027325B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing novel polymers. More specifically, a monomer capable of radical polymerization is radically polymerized in the presence of thiol acid, and the resulting polymer having a thiol acid ester group at the end is treated with an alkali or an acid. The present invention relates to a method for producing a polymer.

In general, thiol acid esters are easily decomposed with bases or acids to provide mercapto groups, and are thus important precursors during the synthesis of mercaptans or the introduction of mercapto groups. Thiolate esters are also important in the synthesis of polymers with mercapto groups, and one way to synthesize polymers with mercapto groups is, for example, by radical polymerization of vinyl monomers having thiolate esters in their side chains, followed by polymerization with bases or acids. Proposed methods include decomposing it to form a mercapto group, and adding thiol acid to the double bond of polyisoprene or polybutadiene to form a thiol acid ester, which is then decomposed with a base or acid to form a mercapto group.

Mercapto groups in polymers play an important role in secondary structure and activity through the formation of disulfide bonds, as seen in cysteine-containing proteins and enzymes, and are an extremely interesting problem in the field of biochemistry. be.

In the field of synthetic polymers, many attempts have been made to synthesize polymers having mercapto groups in their side chains, with the aim of producing polymers with oxidation-reduction ability and polymers with heavy metal trapping ability through mercaptide formation. In addition, attempts have been made to modify polymers through polymer reactions that take advantage of the high reactivity of mercapto groups, and there are many research examples. However, on the other hand, mercapto groups are extremely susceptible to oxidation, and polymers with a certain amount of mercapto groups are oxidized in the air, forming disulfide bonds, crosslinking, and becoming insolubilized, which has prevented industrial use. do not have.

The present inventors investigated a method for producing a polymer having a mercapto group that has a highly reactive mercapto group and does not become insolubilized by oxidation. When monomers are radically polymerized, thiol acid acts as a chain transfer agent and is introduced at the end of the polymer in the form of thiol ester.By treating this polymer with an alkali or acid, the thiol ester is decomposed and the end The present invention was completed based on the discovery that a polymer having a mercapto group can be obtained.

Thiol acids used in the present invention include organic thiol acids having a -COSH group. For example, thiol acetic acid, thiol propionic acid, thiol butyric acid,
Examples include thiolvaleric acid, and among them, thiolacetic acid is the most preferred because it has good decomposition of the thiolate ester at the polymer terminal.

The production method of the present invention can be applied to any monomer that can be radically polymerized, and is not particularly limited. Monomers that can be radically polymerized include olefins such as ethylene, propylene, and isobutylene, acrylic acid, methacrylic acid, and their esters such as methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, dodecyl acrylate, and acrylic. 2-hydroxyethyl acid,
Methyl methacrylate, ethyl methacrylate, butyl methacrylate, 2-ethylhexyl methacrylate, dodecyl methacrylate, 2-hydroxyethyl methacrylate, dimethylaminoethyl acrylate, dimethylaminoethyl methacrylate and their quaternized products, acrylamide, methacryl Amide, N-methylolacrylamide, N,N-
Dimethylacrylamide, acrylamide-2-
Acrylamide monomer of methylpropanesulfonic acid and its sodium salt, styrene, α-
Styrenic monomers such as methylstyrene, P-styrene sulfonic acid and its sodium and potassium salts, other fluorine-containing monomers such as acrylonitrile, methacrylonitrile, N-vinylpyrrolidone, and vinyl fluoride, vinylidene fluoride, and tetrafluoroethylene. Examples include monomers. These monomers can be used alone or in combination, and include vinyl ether, allyl ether,
There is nothing wrong with using monomers such as allyl esters that do not radically polymerize alone or are difficult to radically polymerize as a copolymer. However, when the produced polymer has double bonds, such as dienes, the thiol produced during decomposition of the thiol acid ester may be added to the double bonds of the polymer, and the object of the present invention may not be achieved, so this is not preferable. do not have.

The polymerization of the radically polymerizable monomer in the presence of thiol acid in the present invention can be carried out by any method such as bulk polymerization, solution polymerization, pearl polymerization, or emulsion polymerization in the presence of a radical polymerization initiator. It can be selected depending on the properties of the polymer to be produced and the properties of the polymer to be produced. There are no particular restrictions on the amount of thiol acid added to the polymerization system and the method of addition, and should be appropriately determined depending on the physical properties of the desired polymer. Further, as the polymerization method, known methods such as a batch method, a semi-batch method, and a continuous method can be employed.

As the radical polymerization initiator, known radical polymerization initiators such as 2,2'-azobisisobutyronitrile, benzoyl peroxide, and carbonate peroxide can be used, but 2,2'-azobisisobutyronitrile, etc. An azo initiator is preferred because it is easy to handle.
Also, known initiation systems such as radiation, electron beam, and light can also be used. It is desirable to adopt an appropriate polymerization temperature depending on the type of initiator used, but it is usually 10
Selected from the range of ~90℃.

After the completion of polymerization, the monomer is removed and taken out from the polymer having a thiol acid ester at the end, and then the thiol acid ester is decomposed by treatment with an alkali or acid to produce a polymer having a mercapto group at the end. You can get it. In terms of reaction rate and selectivity, it is more preferable for the decomposition reaction of a polymer having a thiol acid ester at its terminal to be carried out in a solvent that can dissolve or swell the polymer. As alkalis and acids, common amines such as sodium hydroxide, potassium hydroxide, ammonia, dimethylamine and diethylamine, hydrochloric acid, sulfuric acid, and acetic acid are used, but the chemical properties of the polymer must be carefully considered. You need to make a selection. For example, with polyacrylic esters, if a strong alkali such as sodium hydroxide is used, not only the terminal thiol ester but also the ester portion of the polymer will be decomposed, making it impossible to obtain the desired polymer.
In this case, by using a weak alkali such as ammonia and setting the reaction conditions appropriately, the ester moiety of the polymer can be decomposed with almost no decomposition.
For example, the desired polymer can be obtained. It is necessary to appropriately set the conditions for selectively decomposing the terminal thiol acid ester, that is, the selection of reaction solvent, alkali or acid, reaction temperature, and reaction time for each polymer.

The composition, degree of polymerization, distribution of degree of polymerization, etc. of the polymer having a mercapto group at the end of the present invention are not particularly limited, and may be appropriately determined depending on the purpose for which the polymer is used. The polymer obtained in this way is
The reactivity of the mercapto group present at the terminal, such as addition to compounds with double bonds, substitution reactions with halogen compounds, redox decomposition reactions in combination with oxidizing agents, etc., is utilized to make high-density polymers that can be used in an extremely wide range of ways. It is a new reactive material, and a block copolymer can be produced, for example, by radical polymerization in the presence of the polymer obtained in the present invention having a mercapto group at its terminal.

The present invention will be specifically explained below with reference to Examples, but the present invention is not limited by these in any way.

It should be noted that both the middle part of the example and the percentage are based on weight.

Example 1 Methyl methacrylate (hereinafter abbreviated as MMA) 290
1 part and 4.6 parts of thioacetic acid were placed in a reaction vessel, and after the interior was sufficiently replaced with nitrogen, the external temperature was raised to 85°C, and 2.
Contains 0.3 part of 2′-azobisisobutyronitrile
10 parts of MMA was added and polymerized. The polymerization rate after 1.5 hours was 78.8%. After polymerization, dilute with acetone and
- The polymer was precipitated by pouring it into hexane, and the reprecipitation purification was repeated three times in an acetone/water system to remove unreacted MMA.

Next, 200 g of this polymer was dissolved in a mixed solvent of 320 g of acetone and 80 g of methanol, and 10% NaOH
12g of methanol solution was added and reacted at 40°C for 2.5 hours. Subsequently, the polymer was poured into water containing 50 ml of 1N H ₂ SO ₄ in Step 5, and the precipitated polymer was separated, thoroughly washed with water, and dried.
Got PMMA. This PMMA has [η] = 0.06 (dl/g) from [η] measurement at 30°C in acetone,
The amount of mercapto group was 9.99×10 ⁻⁵ eq/g as a result of titration with iodine in an acetone-water system.

Example 2 n-butyl methacrylate (hereinafter abbreviated as BMA)
Put 290 parts of thioacetic acid and 3.2 parts of thioacetic acid into a reaction container, and after thoroughly purging the inside with nitrogen, raise the internal temperature to 85°C.
10 parts of BMA containing 0.3 parts of 2,2'-azobisisobutyronitrile was added and polymerized. The polymerization rate after 2 hours was 75.2%. After polymerization, it is diluted with acetone and poured into methanol to precipitate the polymer.
The reprecipitation purification was repeated three times using an acetone/methanol system to remove unreacted BMA.

Next, 200 g of this polymer was dissolved in a mixed solvent of 320 g of acetone and 80 g of methanol, and 10% NaOH
10 parts of methanol solution was added and reacted at 40°C for 2.5 hours. Subsequently, the polymer was poured into water containing 40 ml of 1N H ₂ SO ₄ in Step 5, and the precipitated polymer was separated, thoroughly washed with water, and dried to obtain PBMA having a mercapto group at one end. This PBMA was prepared in toluene at 30°C.
[η] was measured as [η] = 0.07 (dl/g), and the amount of mercapto group was 6.82×10 ^-5 eq/g as a result of titration with iodine in an acetone-water system.

Example 3 290 parts of styrene and 2.5 parts of thiol acetic acid were placed in a reaction vessel, and the inside was sufficiently replaced with nitrogen.
The internal temperature was raised to 60°C, and 10 parts of styrene containing 0.3 parts of 2,2'-azobisisobutyronitrile was added for polymerization. The polymerization rate after 2 hours was 15.2%. After polymerization, the polymer was poured into methanol to precipitate it, and reprecipitation purification was repeated three times in an acetone/methanol system to remove unreacted ethylene.

Next, 35 g of this polymer was dissolved in a mixed solvent of 100 g of acetone and 10 g of methanol, 12 g of a 10% NaOH methanol solution was added, and the mixture was reacted at 40° C. for 2.5 hours. Subsequently, the polymer was poured into water containing 50 ml of 1N H ₂ SO ₄ in Step 5, and the precipitated polymer was separated, thoroughly washed with water, and dried to obtain polystyrene having a mercapto group at one end. This polystyrene was measured as [η] at 30℃ in toluene, [η] = 0.1 (dl/g).
The amount of mercapto groups was determined to be 7.50×10 ⁻⁵ eq/g by titration with iodine in an acetone-water system.

Example 4 290 parts of acrylic acid and 6.1 parts of thiol acetic acid were placed in a reaction vessel, the interior was sufficiently replaced with nitrogen, the internal temperature was raised to 60°C, and 0.3 parts of 2,2'-azobisisobutyronitrile was added. 10 parts of acrylic acid was added and polymerized. The polymerization rate after 2 hours was 35.2%.
After polymerization, the polymer was poured into acetone to precipitate, and reprecipitation purification was repeated three times in a methanol/acetone system to remove unreacted acrylic acid.

Next, 90 g of this polymer was dissolved in 100 g of methanol, 50 ml of 1N methanol-hydrochloric acid was added, and the mixture was reacted at 40° C. for 5 hours. Subsequently, the mixture was poured into acetone, and the precipitated polymer was separated, dried, and purified by reprecipitation twice in a water/acetone system to obtain polyacrylic acid having a mercapto group at one end. 2 mol/l of this polyacrylic acid as sodium salt
When [η] was measured at 30°C in a NaOH aqueous solution, [η] = 0.2 (dl/g), and the amount of mercapto group was determined to be 9.65 × as a result of titration with iodine in water.
It was 10 ^-5 eq/g.

Example 5 Weighed 20 parts of thiol acetic acid, 100 parts of tetrafluoroethylene and 1.0 part of 2,2'-azobisisobutyronitrile into an autoclave, and heated them at 80°C for 5 parts.
Polymerized for hours. After polymerization, unreacted thiol acetic acid was removed under reduced pressure, 100 parts of methanol was added under a nitrogen stream, and after dissolution, 1.5 g of 28% sodium methylate solution was added, and stirring was continued for 1 hour at room temperature. Next, 10 ml of 1N hydrochloric acid-methanol solution was added, followed by distilled water (1), and the lower oil layer was taken out. Distill this and 40℃～80℃/3mm
20g of Hg fraction was obtained. When titrated with iodine in acetone-water system, 3.0×10 ^-3 eq/g
The presence of a mercapto group was confirmed.

Claims (1)

[Claims] 1. A monomer having only one radically polymerizable double bond in one molecule (excluding vinyl ester monomers) is radically polymerized in the presence of thiol acid, and the resulting polymer is treated with an alkali. Alternatively, a method for producing a polymer having a mercapto group at a terminal, which comprises treating with an acid. 2. The method for producing a polymer having a mercapto group at a terminal according to claim 1, wherein the thiol acid is thiol acetic acid.