JPH0713141B2 - Process for producing polyether having mercapto group at terminal - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION A. Field of Industrial Application The present invention relates to a novel method for producing a polyether having a mercapto group at both ends or one end.

B. Prior Art The mercapto group is a functional group that has unique reactivity and is useful in synthesis. Further, the polyether is useful as a soft segment as an adhesive, a sealing agent, and a component imparting flexibility to various polymers. Therefore, when the mercapto group is introduced into the polyether, the specific reactivity of the mercapto group can be utilized and the application of the polyether can be expanded.

As a method of introducing a mercapto group into the polyether,
A method of reacting thiourea using a polyether diol as a starting material, a method of coexisting a thiolcarboxylic acid or a thiol alcohol when polycondensing a polyether diol and a dicarboxylic acid, and a polyether diol When the polyisocyanate of diisocyanates is subjected to a polyaddition reaction, a method in which a thiol alcohol is allowed to coexist is considered, but in these methods, an undesired side reaction occurs, or a large amount of ester bonds causes problems in water resistance or alkali resistance. Since urethane bonds are included in the target product, improvement in this respect is strongly demanded.

C. Problems to be Solved by the Invention The present invention provides a novel method for producing a polyether having a mercapto group only at both ends or one end, which can solve the above problems.

D. Means for Solving the Problem The inventors of the present invention have conducted extensive studies as a result of achieving the above-mentioned object, and as a result, a polyether having a double bond at both ends or one end has a general formula: (However, R is an alkyl group having 1 to 10 carbon atoms, a phenyl group,
Represents an alkyl group-substituted phenyl group. It was found that a polyether having a mercapto group at both ends or one end can be efficiently produced by adding a thiocarboxylic acid represented by) and then decomposing the resulting thioester group by hydrolysis, transesterification, etc. The present invention has been completed.

As the polyether used in the present invention, any polyether having a double bond at both ends or one end can be used.

Examples of the group containing a terminal double bond include a vinyl group, an allyl group, a vinyloxy group, an allyloxy group, an acryloxy group, and a methacryl group, and among them, an allyloxy group (CH ₂ ═CH—CH ₂ —O -) Is a desirable functional group in terms of stability and reactivity.

As the structural unit constituting the polyether used in the present invention, as long as it is bonded by an ether bond, it is not limited at all, for example, R ₁ O (where R ₁ has 1 to 20 carbon atoms). Represents a straight-chain or branched alkylene group), or a structural unit represented by
A polyether composed of at least one species is preferably used.

Further, the polyether used in the present invention is mainly composed of an ether bond, but may be in a small amount so as not to impair the object of the present invention, for example, not to impair the water resistance and alkali resistance of the target product. For example, other binding styles may be included. Examples of such a bonding mode include ester bond, urethane bond, thioether bond,
A disulfide bond, a polysulfide bond, an acetal bond, etc. are mentioned.

The molecular weight of the polyether used in the present invention is not particularly limited, but is preferably 200 to 100,000, more preferably 500 to 50,000. If the molecular weight is too low, it becomes difficult to separate the product from the unreacted thiocarboxylic acid after the addition reaction, and conversely, if the molecular weight is too high, the reactivity decreases and the addition reaction takes a long time. This is not desirable.

Thiocarboxylic acid used in the present invention The R group of is an alkyl group having 1 to 10 carbon atoms, a phenyl group, or an alkyl-substituted phenyl group. Among them, R = CH ₃ , that is, thioacetic acid, has the reactivity and the separability after the addition reaction. Are suitable.

The addition reaction of a polyether having a double bond at both ends or one end with a thiocarboxylic acid may be an ion addition reaction or a radical addition reaction, but the radical addition reaction is more preferably used. In the ion addition reaction, the addition reaction becomes faster when the system is made alkaline, but since the thiocarboxylic acid is acidic, a large amount of alkaline substance is required to make the system alkaline. It is more disadvantageous than the reaction.

The addition reaction may or may not use a solvent, but it is preferable to use a solvent when the polyether used is crystalline or has a high viscosity. Such a solvent is not particularly limited as long as it does not inhibit the addition reaction. For example, it is appropriately selected from alcohols, aromatic hydrocarbons, ethers, esters, ketones and the like in consideration of solubility of polyether and thiocarboxylic acid.

The amount of the polyether and thiocarboxylic acid used in the addition reaction is such that the molar ratio of both ends or one terminal double bond of the polyether and the thiocarboxylic acid is 1: 1 to 1:10, and more preferably 1: 1.1 to 1 : 5 is selected. When the addition reaction is fast, the thiocarboxylic acid may be used in a small excess with respect to the terminal double bond of the polyether, and when the addition reaction is slow, it may be used in an excess amount.

The temperature of the addition reaction is appropriately selected from the range of 10 to 200 ° C, but is usually selected in the range of 20 to 70 ° C.

As a catalyst used in the radical addition reaction, a usual radical generator is preferably used. Examples thereof include peroxides such as benzoyl peroxide and azo radical generators such as α, α′-azobisisobutyronitrile. The amount of catalyst used is not particularly limited, but usually 1 p
It is selected from the range of pm to 5%, preferably the range of 10 to 1000 ppm.

The addition reaction is carried out until the reaction is completed, but usually 1
~ 10 hours is enough.

When the thiocarboxylic acid used in the addition reaction is in excess, unreacted thiocarboxylic acid may be recovered and removed. In this case, the thiocarboxylic acid is distilled by distillation depending on the type of polyether or thiocarboxylic acid used. The method of removing, the method of extracting with a suitable solvent, etc. are appropriately selected.

The thioester group-containing polyether produced by the addition reaction is converted to a polyether containing a mercapto group at both ends or one end by hydrolysis with an acid catalyst or an alkali catalyst or transesterification reaction. To be done. Among these, the transesterification reaction using an alcohol as a solvent and an alkali catalyst is simple and preferable. The alcohol used is not particularly limited, but methanol,
Ethanol or the like is preferably used. The alkali catalyst is not particularly limited, but alkali metal hydroxide (eg sodium hydroxide), ammonia or the like is preferably used. The amount of alkali catalyst used depends on the pH of the reaction system being 8-12.
It is selected as appropriate. The reaction is carried out until completion, but usually about 1 to 10 hours is sufficient. Further, the mercapto group formed is apt to be oxidized to disulphide, particularly under alkaline conditions, and therefore the transesterification reaction is preferably carried out in an atmosphere of an inert gas such as nitrogen.

After completion of the transesterification reaction, in some cases, after being neutralized with an acid such as acetic acid or hydrochloric acid, appropriate operations such as concentration, washing, extraction, and drying are performed to obtain a polyether having a mercapto group at both ends or one end. can get. Depending on the purpose, the neutralized solution may be used as it is.

The polyether having mercapto groups at both ends or one end obtained in the present invention is an epoxy resin-curable type adhesive, a one-component type sealing material by air oxidation, and a two-component type sealing agent using peroxide as a curing agent. It is preferably used for materials and the like. In addition, by utilizing the fact that the reactivity of the mercapto group to radicals is large and applying it to the radical polymerization system of vinyl monomers by the chain transfer mechanism, it is possible to synthesize block copolymers of various polymers and polyethers. It can be applied in a wide range of fields.

E. OPERATION AND EFFECTS OF THE INVENTION The present invention relates to a novel method for producing a polyether having a mercapto group at both ends or one end, and a mercapto group having a specific reactivity with a high yield and a simple method. Can be introduced into both ends or one end of the polyether, which makes it possible to further expand the field of application of the polyether.

Hereinafter, the production method of the present invention will be described with reference to examples, but the present invention is not limited thereto.
In addition, "parts" and "%" mean "parts by weight" and "% by weight" unless otherwise specified.

Example 1. To a mixture of 100 parts of polypropylene oxide having an allyloxy group at both ends (molecular weight 3000, manufactured by NOF CORPORATION) and 0.01 part of benzoyl peroxide, while stirring at 30 ° C.,
10.1 parts of thioacetic acid was added dropwise over 1 hour. The reaction mixture
After mixing for 2 hours at 30 ℃, use a vacuum pump to
Unreacted thioacetic acid was removed at 2 ° C and 2 mmHg.

0.27 parts of sodium hydroxide was added to 150 ml of methanol in this reaction product.
Dissolve in 1 part and add in a nitrogen atmosphere for 3 hours at 60 ℃
It was stirred at. After cooling, 0.41 part of acetic acid was added to neutralize, methanol was removed at 2 to 10 mmHg at room temperature using a vacuum pump, a small amount of precipitated sodium acetate was removed by filtration, and a polymer having a mercapto group at the end was removed. 98 parts of ether (96% yield) was obtained.

Part of this polyether was oxidized with iodine, excess iodine was titrated with an aqueous sodium thiosulfate solution to determine iodine consumption, and the content of the mercapto group was calculated.
It was 6.3 × 10 ⁻⁴ eq / g. From this, the conversion rate from the double bond of the mercapto group was determined to be about 96 mol%.

In addition, ¹ H-NM of this terminal mercapto group-containing polyether
When the R spectrum was measured, absorption of olefinic protons observed in the raw material polyether was hardly observed, and absorption newly attributed to the mercapto group was observed, and a polyether containing a mercapto group at the end was produced. It became clear that it was possible.

Example 2. 100 parts of polyether having one end having an allyloxy group and the other end having a butoxy group (molecular weight 1600, ethylene oxide / propylene oxide = 75/25 (molar ratio), manufactured by NOF CORPORATION), While stirring at 30 ° C., 5.7 parts of thioacetic acid was added dropwise to a mixture of 0.01 parts of α, α′-azobisisobutyronitrile over 1 hour. After further mixing at 30 ° C. for 2 hours, unreacted thioacetic acid was removed at 30 ° C. and 2 mmHg using a vacuum pump.

To this reaction product was added 0.5 part of sodium hydroxide dissolved in 150 parts of methanol, and the mixture was placed in a nitrogen atmosphere for 3 hours at 40 ° C.
It was stirred at. After cooling, it was neutralized by adding 0.75 part of acetic acid to obtain a methanol solution of a polyether having a mercapto group at one end and containing a small amount of sodium acetate as an impurity.
The conversion rate of double bond to mercapto group was 99 mol%, and the yield was quantitative.

Examples 3 to 6 Polyethers having a mercapto group at the terminal were produced in the same manner as in Example 1 except that the type of polyether used was changed to that described in Table 1. The results are shown in Table 1 together with Examples 1 and 2.

Example 7. A polyether having mercapto groups at both ends was produced in the same manner as in Example 1 except that thioacetic acid in Example 1 was changed to thiopropionic acid. The results are shown in Table 1.

From Table 1, it is clear that a polyether having a mercapto group at both ends or one end can be produced with extremely high yield by the production method of the present invention.

Claims (5)

[Claims] 1. A polyether having a double bond at both ends or at one end is represented by the general formula (However, R represents an alkyl group having 1 to 10 carbon atoms, a phenyl group, or an alkyl group-substituted phenyl group.) After adding a thiocarboxylic acid, the resulting thioester group is decomposed. A method for producing a polyether having a mercapto group at both ends or one end. 2. The production method according to claim 1, wherein the thiocarboxylic acid is thioacetic acid. 3. The production method according to claim 1, wherein the group containing a double bond of a polyether having a double bond at both ends or one end is an allyloxy group. 4. The production method according to claim 1, wherein the addition reaction of the polyether having a double bond at both ends or one end with a thiocarboxylic acid is a radical addition reaction using a radical generator. 5. The decomposition reaction of a thioester group is carried out with 1 to 1 carbon atoms.
The process according to claim 1, which is carried out by adding a catalytic amount of an alkali metal hydroxide, an alkaline earth metal hydroxide, ammonia or amines in the presence of 10 aliphatic alcohols.