JPH0113727B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing modified polybutadiene. More particularly, the present invention relates to a process for producing modified polybutadiene in which at least 5% of all double bonds are converted to dihalocyclopropane groups. Modified polybutadiene in which most of the double bonds of cis-1,4-polybutadiene are converted into dihalocyclopropane groups is already known, as disclosed in, for example, US Pat. No. 3,369,012. This US Patent No. 3,369,012 discloses that cis-1,4-polybutadiene is reacted with a carbene prepared from ethyl trichloroacetate and sodium methoxide under anhydrous, nitrogen atmosphere, and low temperature reaction conditions. 90% of all double bonds
It is disclosed that a modified polybutadiene in which up to about 100% of the polybutadiene groups are converted to dihalocyclopropane groups can be obtained, and the description states that the obtained modified polybutadiene is a tough, flame-retardant, rubbery polymer. ing. As a result of various studies on the use of modified polybutadiene in which double bonds are partially converted to dihalocyclopropane groups, the present inventor found that 5 to 75% of the total double bonds in cis-1,4-polybutadiene are dihalocyclopropane groups. We have discovered that vulcanized rubber produced by vulcanizing modified polybutadiene converted to halocyclopropane groups exhibits high resistance to gas and fuel oil permeation. It has also been found that modified cis-1,4-polybutadiene in which the percentage of double bonds converted to dihalocyclopropane groups is within the range of 15% to 95%, exhibits useful properties as a vulcanizable fusible rubber. It was. However, the above method of producing carbene and reacting it with cis-1,4-polybutadiene uses unstable raw materials that easily react with moisture, such as sodium methoxide.
Strict reaction conditions such as a nitrogen atmosphere and low temperature reaction conditions are required. Therefore, although such a method is advantageous as an industrial production method for obtaining modified polybutadiene in which the double bonds of cis-1,4-polybutadiene are partially converted into dihalocyclopropane groups, it is do not have. The present invention provides a method for producing modified polybutadiene having a molecular structure in which all double bonds of cis-1,4-polybutadiene are partially converted to dihalocyclopropane groups, which does not require the severe reaction conditions described above. The purpose is to provide The present invention is characterized in that cis-1,4-polybutadiene is reacted with haloform in the presence of a phase transfer catalyst and an aqueous alkali metal hydroxide solution, wherein at least 5% of all double bonds are dihalocyclopropane groups. It consists of a method for producing modified polybutadiene converted into Next, the present invention will be explained in detail. The cis-1,4-polybutadiene used in the present invention is not particularly limited, but it is generally preferable to use a solid polymer having a cis-1,4 structure content of 90% or more. Haloform, which is a raw material for dihalocyclopropane groups, is a compound also called trihalomethane, and specific examples thereof include chloroform, bromoform, bromodichloromethane, chlorodibromomethane, bromodifluoromethane, and chlorodifluoromethane. . For example, when chloroform is used as a raw material, a dichlorocyclopropane group is introduced into the polybutadiene, and when bromoform is used, a dibromocyclopropane group is introduced into the polybutadiene. Haloform is cis-1,4-polybutadiene
It is preferably used in a proportion of 0.3 to 30 moles per 100 g, and particularly preferably 0.5 to 10 moles per 100 g of cis-1,4-polybutadiene. Examples of phase transfer catalysts used in the present invention include quaternary ammonium salts such as triethylbenzylammonium chloride, tributylbenzylammonium chloride, diethyldodecylbenzylammonium chloride, and tetrabutylammonium chloride; tetraphenylphosphonium chloride, and tetrabutylphosphonium chloride. Quaternary phosphonium salts such as dibenzo-18
Crown ethers such as -crown-6, dicyclohexyl-18-crown-6,18-crown-6; and cryptands such as "2.2.2"-cryptate. For such phase transfer catalysts, for example, M.
Makosza and M. Wawrzyniewicz:
It is described in detail in Tetrahedron Letters, 53 , 4659 (1969), and Japanese Patent Publication No. 4708/1983. The above phase transfer catalyst is preferably used in a proportion of 0.01 to 1.0 g per 100 g of cis-1,4-polybutadiene. In the present invention, a 30 to 65% by weight aqueous solution of sodium hydroxide or potassium hydroxide is generally used as the aqueous alkali metal hydroxide solution.
It is not limited to this type and scope.
In addition, the alkali metal hydroxide aqueous solution has an amount of alkali metal hydroxide contained therein of cis-1,
0.3 to 40 mol per 100 g of 4-polybutadiene,
More preferably, it is added in an amount of 1 to 20 mol. The production method of the present invention usually involves cis-1,4-
It is preferable to prepare a solution in which polybutadiene is dissolved in an organic solvent, add a phase transfer catalyst and an aqueous alkali metal hydroxide solution thereto, and then gradually add haloform to this mixed solution. The organic solvent used to prepare the cis-1,4-polybutadiene solution includes cis-1,4-
There is no particular restriction as long as it dissolves polybutadiene, is sparingly soluble in water, and does not interfere with the reaction.
Examples of such organic solvents include hydrocarbons such as benzene, toluene, xylene, and cyclohexane; halogenated hydrocarbons such as haloforms such as chloroform and bromoform; and carbon tetrachloride.
Examples include halogenated hydrocarbons other than haloform, such as methylene chloride and chlorobenzene. Among these, when a haloform-based halogenated hydrocarbon is used as the organic solvent for preparing the cis-1,4-polybutadiene solution, it is also possible to have it serve as both a reactant and an organic solvent. Further, it is preferable to use the cis-1,4-polybutadiene solution in the reaction as a 2 to 20% (weight/volume) solution. If the concentration of this solution is too high, the solution will have a high viscosity, making stirring difficult and making the reaction operation difficult. on the other hand,
If the concentration of the solution is too low, the reaction efficiency per volume of the reaction system decreases, making it impractical. cis-1 at a concentration in the preferred range as described above,
A 4-polybutadiene solution can be prepared, for example, by adding cis-1,4-polybutadiene to an organic solvent and stirring the mixture at a temperature range of 0 to 80°C, preferably 20 to 60°C, for about 1 minute to 5 hours. -1,4-
How to dissolve polybutadiene or cis-
Cis- obtained by polymerizing 1,4-butadiene
It can be prepared by adding a small amount of a polymerization terminator to a 1,4-polybutadiene-containing reaction solution to terminate polymerization, and using the obtained polymerization reaction solution as it is. The production method of the present invention includes, for example, adding a phase transfer catalyst, an aqueous alkali metal hydroxide solution, and haloform to a cis-1,4-polybutadiene solution, and adding the resulting mixture to 0 to 80°C, preferably 20 to 60°C. This is carried out by stirring at a temperature of 10 minutes or more, preferably about 10 minutes to 10 hours. This reaction proceeds in an emulsified state consisting of an aqueous phase and an organic phase. In order to take out the reaction product after the above reaction is completed, the same method as or a method similar to the method for collecting the product of a normal emulsion polymerization reaction can be used. For example, a method can be used in which the reaction solution is separated into an organic layer and an aqueous layer by using a physical separation means such as a centrifuge, and then the desired reaction product is extracted from the organic layer. The aqueous phase separated by this method can also be reused after adjusting its concentration by adding an alkali metal hydroxide.
Alternatively, after the reaction solution is completed, the reaction solution is thoroughly washed with water to remove the alkali metal hydroxide contained in the aqueous phase, and then an organic solvent (e.g., methanol) that has little solubility for the reaction product is used. ) can be used, for example, a method in which the washed reaction solution is charged into a tank to precipitate and separate the reaction product. The reaction product obtained by the above reaction is a modified polybutadiene in which at least 5% of all double bonds of cis-1,4-polybutadiene used as a raw material are converted into dihalocyclopropane groups. In the above reaction according to the present invention, the starting cis-
The ratio of the number of double bonds converted into dihalocyclopropane groups to the total number of double bonds contained in 1,4-polybutadiene (reaction rate) depends on the type of raw material polymer (cis-1,4-polybutadiene), The type and amount of haloform added, the type and amount of alkali metal hydroxide added, and the concentration of its aqueous solution, the type and amount of catalyst added, the type of reaction solvent, the polymer concentration in the reaction solution, reaction temperature, reaction time, etc. changes depending on the selection of conditions. Therefore, it is possible to obtain modified polybutadiene with various levels of reactivity, from a reaction product with a low reactivity to a reaction product with a reactivity close to 100%. According to the present invention, it is possible to obtain modified polybutadiene with various reaction rate levels as described above, but those with a reaction rate of less than 5% have physical properties and reactivity that differ from the raw material cis-1,4. -Since it is almost the same as polybutadiene, the modification according to the present invention has no particular effect. On the other hand, modified products with a reaction rate of 5% or more are
Since its physical properties and reactivity clearly change compared to the raw material cis-1,4-polybutadiene, it is very useful in practice. For example, if the reaction rate is 5~
Modified cis-1,4-polybutadiene in the range of 75% can be vulcanized to convert it into a rubber that is highly resistant to the permeation of gases, combustible gases, and fuel oils. Also, the reaction rate is 15~
Modified cis-1,4-polybutadiene within the range of 95% exhibits useful properties as a heat-fusible rubber. According to the present invention as described above, cis-1,4
- at least 5% of the total double bonds of the polybutadiene
Modified polybutadiene in which is converted into a dihalocyclopropane group can be obtained under conditions that are easily realized as an industrial production method, such as at room temperature and in the presence of water. Therefore, it is very useful as an industrial method for producing cis-1,4-polybutadiene in which part or most of the cis-1,4 double bonds are converted to halocyclopropane groups. Next, Examples and Comparative Examples of the present invention will be shown. [Example 1] 80 ml of toluene and 5 g of cis-1,4-polybutadiene (cis-1,4 structural content : Approximately 97.5%, [η]:
2.2) was introduced, and the mixture was stirred at 45° C. for about 30 minutes to form a solution. To this solution, a 50% by weight aqueous solution containing 5 g (0.125 mol) of sodium hydroxide and 0.05 g of triethylbenzylammonium chloride (catalyst) were added and mixed with stirring to form an emulsion. Then, 20 ml of chloroform was added while continuing to stir this emulsion and maintaining its temperature at 45°C.
(0.252 mol) was added dropwise over about 10 minutes. After the dropwise addition was completed, stirring was continued for about 1 hour and 50 minutes while maintaining the temperature of the reaction solution at 45°C. Thereafter, approximately the same amount of water as the total amount of the reaction solution was added to the reaction solution and stirred to wash the reaction solution, and then water was removed by liquid separation. After repeating this washing operation of the reaction solution four times, methanol was added to the washed reaction solution. After separating the generated precipitate, this precipitate was dissolved in toluene, and methanol was added to this toluene solution to obtain a precipitate again. This precipitate was taken out and dried at room temperature under reduced pressure for 24 hours to obtain a purified reaction product. This reaction product was confirmed to have a cyclopropane group in its molecular structure by measurement of ¹³ C-NNR spectrum, and was confirmed to contain a chlorine atom by quantitative analysis of halogen. Therefore,
The reaction product was identified as partially dichlorocyclopropanated polybutadiene (ie, dichlorocyclopropanated cis-1,4-polybutadiene). As a result of calculating the reaction rate of the reaction product from the halogen analysis value, it was confirmed that the reaction rate was 23.7%. [Example 2-3] Example 1 except that the amount of chloroform used was changed
Dichlorocyclopropanated cis-1,4-polybutadiene was obtained by carrying out the same operation as above. Table 1 shows the amount of chloroform used and the reaction rate.

[Table] [Example 4-5: Comparative Example 1] Dichlorocyclopropanation cis-1,
4-Polybutadiene was obtained. Table 2 shows the amount of catalyst used and the reaction rate.

[Table] [Example 6-7] Dichlorocyclopropanation of cis-1,4 was carried out in the same manner as in Example 1 except that the amount of catalyst used was changed to 0.1 g and the amount of sodium hydroxide was changed.
- Obtained polybutadiene. The amount of sodium hydroxide used and the reaction rate
Shown in the table.

[Table] [Example 8-12] Sodium hydroxide 10 instead of a 50% aqueous solution containing 5 g (0.125 mol) of sodium hydroxide
Dichlorocyclopropanation cis-1, 4-Polybutadiene was obtained. Table 4 shows the catalysts used and the reaction rates.

[Table] Muchloride

[Table] [Example 13-14] Sodium hydroxide 20% instead of a 50% aqueous solution containing 5g (0.125 mol) of sodium hydroxide
Using a 50% by weight aqueous solution containing g (0.500 mol),
The same procedure as in Example 1 was carried out except that tetrabutylammonium bromide was used as a catalyst and the amount used was changed to 0.01 g, and bromoform was used instead of chloroform and the amount used was changed. A cyclopropanated polybutadiene (ie, dibromocyclopropanated cis-1,4-polybutadiene) was obtained. Table 5 shows the amount of bromoform used and the reaction rate.

[Table] [Example 15] Dibromosic Propanated cis-1,4
- Obtained polybutadiene. The reaction rate was 10.1%. [Example 16] Add 0.1 g of 2,6-di-tert-butyl-para-cresol (stabilizer) to a toluene solution of cis-1,4-polybutadiene, and add 5 ml of sodium hydroxide.
The same procedure as in Example 1 was carried out, except that a 50 wt% aqueous solution containing 10 g (0.250 mol) of sodium hydroxide was used instead of a 50 wt% aqueous solution containing 10 g (0.125 mol) of sodium hydroxide, and the reaction time was changed. Cyclopropanated cis-1,4-polybutadiene was obtained. When the reaction time was 10 minutes, the reaction rate was 24.6%, when the reaction time was 45 minutes, the reaction rate was 49.3%;
The reaction rate was 63.4% in 120 minutes. [Example 17] Dichlorocyclopropanated cis-1,4-polybutadiene was obtained by carrying out the same operation as in Example 1 except that the same weight of potassium hydroxide was used instead of sodium hydroxide. The reaction rate was 15.0%. [Example 18-19] Example 1 except that the concentration of the aqueous solution was changed without changing the amount of sodium hydroxide used (5 g)
Dichlorocyclopropanated cis-1,4-polybutadiene was obtained by carrying out the same operation as above. Table 6 shows the concentration and reaction rate of the sodium hydroxide (NaOH) aqueous solution.

[Table] [Example 20-22] Dichlorocyclopropanation cis-1, 4-Polybutadiene was obtained. The reaction temperature and reaction rate are shown in Table 7.

[Table] [Example 23] Benzene was used instead of toluene as the reaction solvent, the reaction temperature was changed to 50°C, and 20 g of sodium hydroxide was used instead of the 50% by weight aqueous solution containing 5 g (0.125 mol) of sodium hydroxide. (0.500 mol)
Dichlorocyclopropanated cis-1,4-polybutadiene was obtained by carrying out the same operation as in Example 1 except for using a 50% by weight aqueous solution containing . The reaction rate is
It was 85.6%. [Example 24] Dichloromethane was used instead of toluene as the reaction solvent, the reaction temperature was changed to 35°C, and 20 g of sodium hydroxide was used instead of the 50% by weight aqueous solution containing 5 g (0.125 mol) of sodium hydroxide.
Dichlorocyclopropanated cis-1,4-polybutadiene was obtained by carrying out the same operation as in Example 1 except that a 50% by weight aqueous solution containing (0.500 mol) was used. The reaction rate was 55.3%. [Example 25] In a 200 ml four-neck flask equipped with a stirrer, a thermometer, a dropping funnel and a reflux condenser, 100 ml of chloroform, 5 g of cis-1,4-polybutadiene (cis-1,4 structural content : Approx. 97.5, [η]:
2.2) and 50 mg of 2,6-di-tert-butyl-para-cresol (stabilizer) and the mixture
The mixture was stirred at 45°C for about 30 minutes to form a solution. Next, 0.05g of triethylbenzylammonium chloride (catalyst) was added to this solution and mixed with stirring.The stirring of this solution was further continued, and the temperature was raised to 45%.
20 g of sodium hydroxide (0.500
A 50% by weight aqueous solution containing mol) was added dropwise over about 10 minutes. After the dropwise addition was completed, stirring was continued for about 10 minutes while maintaining the temperature of the reaction solution at 45°C. Thereafter, washing and drying were carried out in the same manner as in Example 1 to obtain dichlorocyclopropanated cis-1,4-
Polybutadiene was obtained. The reaction rate was 62.1%. [Example 26] Dichlorocyclopropanated cis-1,4-polybutadiene was obtained by carrying out the same operation as in Example 25 except that stirring of the reaction solution was continued for about 1 hour and 50 minutes after the completion of dropping the aqueous sodium hydroxide solution. Ta. The reaction rate was 98.1%. [Example 27] Cis-1,4-polybutadiene polymerization solution prepared by polymerizing 1,4-butadiene (cis-1,4 structure content in polybutadiene: approximately 97.5%,
[η]: 2.2) was added with a benzene solution of an antiaging agent (BHT), and then 15 parts of water per 1 m ³ of the polymerization solution was added and stirred to stop the polymerization and decompose the catalyst. After water was separated from this mixture by liquid separation, unreacted butadiene was removed under reduced pressure. Benzene was added to the obtained polymer solution to adjust the polymer concentration in the solution to 5 g/80 ml (benzene). Regarding the above polymer solution, the same operation as in Example 1 was carried out except that a 50% by weight aqueous solution containing 10 g (0.250 mol) of sodium hydroxide was used and the amount of catalyst used was changed to 0.01 g. Dichlorocyclopropanation cis- 1,4-polybutadiene was obtained. The reaction rate was 13.3%.

Claims (1)

[Claims] 1. A method characterized in that cis-1,4-polybutadiene is reacted with haloform in the presence of a phase transfer catalyst and an aqueous alkali metal hydroxide solution, wherein at least 5% of all double bonds are dihalocyclo. A method for producing modified polybutadiene converted into a propane group. 2. The modified polybutadiene according to claim 1, wherein the phase transfer catalyst is selected from the group consisting of quaternary ammonium salts, quaternary phosphonium salts, crown ethers, and cryptands. Production method. 3. The method for producing modified polybutadiene according to claim 1, characterized in that 0.3 to 30 moles of haloform are used per 100 g of cis-1,4-polybutadiene.