JP2850432B2 - Copolymer and method for producing the same - Google Patents

Description

The present invention relates to a novel chloroprene block copolymer, which is useful as a thermoplastic elastomer or a pressure-sensitive adhesive.

[Prior Art] Various studies have been made on the synthesis of block copolymers, but anionic polymerization is industrially used. However, in the anionic polymerization of a chlorine-containing monomer, there is a problem in that the interaction between the monomeric chlorine and the metal atom constituting the catalyst is generally large, and the catalyst is deactivated due to the elimination of chlorine ( For example, BLYersali-mskii, Vysokomol. Soyed., 6-7.
Vol., 1294, 1964).

Further, even when polymerization is performed, the yield is low, and an increase in molecular weight cannot be expected. Furthermore, the produced polymer has no living property, and it is difficult to synthesize a copolymer and to control the molecular weight of the copolymer. Therefore, it is difficult to obtain a high molecular weight copolymer by ionic polymerization of a chlorine-containing monomer, and synthesis of a copolymer using a chlorine-containing diene-based monomer by an anion polymerization method has not been successful.

On the other hand, a living polymer such as polystyryllithium obtained by polymerizing an anionic polymerizable monomer using an initiator such as alkyllithium is coupled with azoisobutyronitrile, and an azo group is formed in one molecular chain. Investigations have been conducted to obtain a polymer having one. (For example, European Polymer Journal)
Journal, Vol. 12, p. 317, 1976). In this case, an azo group-containing polymer having an extremely small molecular weight distribution can be obtained, but there is a disadvantage that a quantitative coupling reaction between the polymers does not easily occur. Therefore, it is difficult to quantitatively synthesize the block copolymer.

As described above, in the prior art, in the production of an ABA type block copolymer using a polymer having an azo group in the main chain, the molecular weight of the segment (A) in the block copolymer Is difficult to control. The molecular weight of the segment (A) and its molecular weight distribution are important factors that greatly affect the physical crosslinkability of the elastomer, particularly in a block copolymer intended for a thermoplastic elastomer.

[Problems to be Solved by the Invention] The present invention has been conventionally difficult (1) to produce an ABA type triblock copolymer using a base monomer,
And (2) the molecular weight of the segment (A) of the copolymer,
Another object of the present invention is to provide a production method capable of controlling the molecular weight distribution.

[Means for Solving the Problems] As described above, it is difficult to obtain a block copolymer using a base-containing monomer using conventional techniques. As a result of intensive studies to synthesize such a block copolymer, the following general formula [II] (Where R ¹ represents an alkyl group or an aryl group,
R ² represents an alkylene group having 1 to 18 carbon atoms, an aryl group and / or
Or at least one selected from an alkylene group having 1 to 18 carbon atoms substituted with a cyano group, an alkylene group having 1 to 18 carbon atoms substituted with an arylene group and / or a cyano group, m represents a degree of polymerization, and Represents an integer. Using a polymer having one azo group in the molecular chain represented by the following formula as a polymerization initiator, and polymerizing a chloroprene monomer, the following general formula [I] (Where R ¹ is an alkyl group or an aryl group, R ² is an alkylene group having 1 to 18 carbon atoms, an alkylene group having 1 to 18 carbon atoms substituted with an aryl group and / or a cyano group, an arylene group, And / or 1 to 1 carbon atoms substituted with a cyano group
Represents at least one selected from 18 alkylene groups,
M represents a chloroprene residue, m and n each represent a degree of polymerization, and represent a positive integer. The present inventors have found that a block copolymer represented by the formula (1) can be obtained, and have reached the present invention.

 Hereinafter, the present invention will be described in detail.

The present invention relates to a novel polymer obtained by polymerizing chloroprene using an azo group-containing polystyrene as an initiator and a method for producing the same. More specifically, the above general formula [II] (Where R ¹ is an alkyl group or an aryl group, R ² is an alkylene group having 1 to 18 carbon atoms, an alkylene group having 1 to 18 carbon atoms substituted with an aryl group and / or a cyano group, an arylene group, And / or 1 to 1 carbon atoms substituted with a cyano group
Represents at least one selected from 18 alkylene groups,
m represents a degree of polymerization and represents a positive integer. The above general formula [I] obtained by polymerizing chloroprene using a polymer having one azo group per molecular chain represented by the following formula as a polymerization initiator: (Where R ¹ is an alkyl group or an aryl group, R ² is an alkylene group having 1 to 18 carbon atoms, an alkylene group having 1 to 18 carbon atoms substituted with an aryl group and / or a cyano group, an arylene group, And / or 1 to 1 carbon atoms substituted with a cyano group
Represents at least one selected from 18 alkylene groups,
M represents a chloroprene residue, m and n each represent a degree of polymerization, and represent a positive integer. ) With a number average molecular weight of 10,0
00-500,000, the number average molecular weight of the styrene segment is 2,500-50,000, and the degree of dispersion (Mw / Mn) is 1.01-1.
50 relating to the novel copolymer.

Examples of the azo group-containing polystyrene used in the present invention include the following.

(Where R is an alkyl group or an aryl group, n
Represents the degree of polymerization of styrene and represents an integer of 500 to 1,000,
m represents the number of methylene units and represents an integer of 1 to 18. These polymers are obtained by coupling living polystyrene obtained by anionic polymerization of styrene by a usual method using an alkyl lithium catalyst with an azo compound. These azo compounds include 2,2′-
Azobis-2-cyanodipropionic acid chloride, 3,3'-azobis-3-cyanodibutylic acid chloride, 4,4'-azobisvaleric acid chloride, 5,5'-azobis-5-cyanodicapro Ic acid chloride, 3,3'-azobis-3,3'-dimethyldipropionic acid chloride, 4,4'-azobis-4;4'-dimethyldibutylic acid chloride, 5,
5'-azobis-5,5'-dimethyldivaleric acid chloride, 4,4'-azobis-dibenzoic acid chloride, 5,5'-azobis-diphenylacetic acid chloride, and 6,6'-azobis- Compounds such as diphenylpropionic acid chloride are exemplified. When the above azo compound is added to a living polymer solution, it is necessary to sufficiently purify the living polymer so that the terminal of the living polymer is not deactivated by impurities in the azo compound. Although the azo compound is relatively stable to moisture, it needs to be performed in an atmosphere without moisture in a purification process such as recrystallization. The dried azo compound is dried under reduced pressure.
It is preferable to use a dehydrating agent such as phosphorus pentoxide. The azo compound is added to the polymer solution in a solution state. Therefore, the solvent must be sufficiently dehydrated as the polymerization solvent. In the dehydration purification of the solvent, it is preferable to use a substance which is usually dehydrated with calcium hydride, distilled, then dehydrated again with an alkali metal such as metallic sodium and distilled. When the solution of the azo compound is added to the living polymer solution, the temperature of the reaction solution is not particularly limited as long as the decomposition of the azo compound does not occur. The solvent of the azo compound is limited in terms of solubility in the solvent used, but it is preferable to use the same solvent as used in the production of the living polymer as much as possible. The reaction temperature is preferably as low as possible, and is preferably from -70 ° C to 0 ° C. The addition of the azo compound solution may be performed gradually or all at once. After the addition, the time until the reaction is completely completed varies depending on the polymerization system and needs to be appropriately set. However, it can be considered that the reaction is usually completed in 3 to 4 hours. After completion of the reaction, the polymer solution is poured into a large amount of a benzene / methanol mixed system to isolate the polymer. If the azo compound remains in the isolated polymer, it induces the formation of a homopolymer at the time of subsequent polymerization, so that reprecipitation purification is preferably performed several times. The purified polymer is dried and isolated by freeze-drying. The anionic polymerization method of styrene itself is known, and a quantitative reaction can be performed according to the known literature.

The chloroprene used in the present invention is preferably obtained by dehydrating using a dehydrating agent such as calcium hydride and then removing the inhibitor by distillation and purifying the product. As the polymerization solvent, aliphatic cyclic hydrocarbon solvents such as cyclohexane and cyclopentane and aromatic hydrocarbons such as benzene, toluene, and xylene, which are used in ordinary radical polymerization, are preferable.

The polymerization temperature is not particularly limited as long as the azo group is thermally decomposed, but is generally preferably from 40 ° C to 60 ° C. Polymerization is 10 hours ~
The polymerization is preferably performed for 20 hours, and the polymerization temperature and the polymerization time are preferably set based on the half-life in the thermal decomposition of the azo compound so that undecomposed azo groups do not remain in the resulting polymer.

According to the present invention, a novel polymer having a narrow styrene segment molecular weight distribution can be obtained.

[Examples] Hereinafter, the present invention will be described in detail with reference to Examples, but this does not limit the present invention in any way.

In addition, the analysis of the polymer of this invention was performed by the following models and measurement conditions.

(1) GPC Tosoh Corp. TSK CP-8000 Column: G4000HX-G2000HXL Solvent: THF Flow rate: 1.0 ml / min. Pressure: 62 kg / cm ² Temperature: 25 ° C. Detector: UV-8000 (2) NMR Varian EM-360 NMR-Spectrometer Measurement conditions: CDC13 solvent, room temperature Standard substance: Tetramethylsilane (3) TEM (transmission electron microscope) Model: JEOL JEM-200FX Polymer film preparation method: Cast from benzene solution Polymer film Dyeing: Osmic acid staining method Reference Example 1 Synthesis of 4,4'-azobis-4-cyanovaleryl chloride 25.0 g of 4,4'-azobis-4-cyanovaleric acid was added to 250
After dissolving in ml of dehydrated benzene and cooling with ice, 50.0 g of phosphorus pentachloride was added. After reacting at 0 ° C. for 5 minutes under stirring, the reaction temperature was raised to room temperature. The reaction was performed for 1 hour in this state. After filtering the reaction solution under nitrogen to remove unreacted substances, benzene was removed from the filtrate by distillation under reduced pressure. The obtained solid was dried under nitrogen in anhydrous ether / hexane (volume ratio).
1/3) The plate was washed three times with 100 ml, and then filtered. The filtrate was dissolved in dehydrated methylene chloride, the solution was poured into anhydrous hexane, and the precipitate was filtered again. The obtained filtrate was dissolved in anhydrous methylene chloride, recrystallized, dried over phosphorus pentoxide under reduced pressure, and 4,4-azobis-4-cyanovaleryl chloride (UV: 242.0, 349.2, mp: 93.0) Synthesis of macroazopolystyrene A stirrer was placed in a 500 ml round-bottom flask equipped with a three-way cock, followed by degassing and heating and drying. Next, 300 ml of anhydrous tetrahydrofuran and 21.42 g of styrene monomer were charged into the flask using a vacuum line. The reaction solution was cooled to -78 ° C with dry ice methanol and stirred for 30 minutes. After performing nitrogen replacement and deaeration three times, 1.6 mol
0.64 ml of an e / 1 concentration n-butyllithium hexane solution was added to initiate polymerization. Ten minutes later, 1 ml of the reaction solution was withdrawn, and immediately thereafter, 10 ml of a solution of azobiscyanovaleryl chloride in tetrahydrofuran was added all at once. Immediately after the addition, the red-orange color of the polystilllithium disappeared, and the color changed to pale yellow. After 10 minutes from the addition, the cooling of the reactor was stopped, the reaction temperature was gradually raised to room temperature, and the coupling reaction was performed for 20 hours.
After the completion of the reaction, the content was poured into a large amount of methanol to isolate the polymer. The obtained polymer was purified twice by reprecipitation with a benzene / methanol system, then lyophilized again with a benzene solution to obtain 21.0 g (yield 98%) of a polystyrene macroazo initiator. The average molecular weight (Mn) of the obtained polymer was 40,000. On the other hand, the number average molecular weight (Mn) of the sampled polymer before coupling was 21,000, and the molecular weight was approximately doubled by the coupling reaction, indicating that the coupling reaction had occurred.

The polymer obtained from the above results is presumed to be a polymer having one azo group per molecule and having the following structure.

Example 1 100 ml fully dried under reduced pressure and equipped with a three-way cock
5.0 g of azo group-containing polystyrene synthesized in Reference Example 1, 80 ml of cyclohexane, and 25.0 g of chloroprene
Was charged. After fully degassing the ampoule and replacing with nitrogen,
The tube was sealed and polymerized at 60 ° C. for 22 hours. After the polymerization, the content of the ampoule was poured into a large amount of methanol to isolate the polymer. Thereafter, the polymer was dried by a conventional method to obtain 15.0 g of a polymer. After dissolving the obtained polymer in cyclohexane, chloroprene homopolymer and polystyrene were removed using acetone. The separated polymer was freeze-dried using benzene and analyzed. ^From a comparison of the peak intensities of the protons of the benzene ring of the styrene segment and the protons of the double bond in the chloroprene segment from ¹ H-NMR, the obtained polymer was found to have a number average molecular weight (Mn) of the styrene segment of 21,000 and chloroprene. It was found that the segment had a number average molecular weight (Mn) of 435,000 (dispersion degree of molecular weight by GPC = 1.48). Fig. 1 shows GP
FIG. 2 shows the ¹ H-NMR measurement results of the C measurement results. When the obtained polymer was cast using benzene, a transparent film having elasticity was obtained. The film was stained by a ruthenic acid staining method and observed with a transmission electron microscope. As a result, it was found that the polymer had a phase separation structure in which a polystyrene phase was uniformly dispersed in a polychloroprene phase. The polymer obtained from the above is presumed to be a styrene / chloroprene block copolymer having the following structure.

Example 2 100 ml fully dried under reduced pressure and equipped with a three-way cock
Was charged with 5.0 g of the azo group-containing polystyrene synthesized in Reference Example 1, 80 ml of cyclohexane, and 2.0 g of chloroprene. After the ampoule was sufficiently degassed and replaced with nitrogen, it was sealed and polymerized at 60 ° C. for 22 hours. After the polymerization, the content of the ampoule was poured into a large amount of methanol to isolate the polymer. Thereafter, the polymer was dried by a conventional method to obtain 12.2 g of a polymer.
After dissolving the obtained polymer in cyclohexane, chloroprene homopolymer and polystyrene were removed using acetone. The separated polymer was freeze-dried using benzene and analyzed. ^From the comparison of the peak intensities of the protons of the benzene ring of the styrene segment and the protons of the double bond portion in the chloroprene segment from ¹ H-NMR, the obtained polymer was found to have a number average molecular weight (Mn) of the styrene segment of 22,000 and chloroprene. The number average molecular weight (Mn) of the segment is 296,000 (dispersion degree of molecular weight by GPC = 1.
39) was found to be a copolymer. FIG. 1 shows the results of GPC measurement, and FIG. 2 shows the results of ¹ H-NMR measurement. Also,
When the obtained polymer was cast using benzene, a transparent film having elasticity was obtained. The film was stained by a ruthenic acid staining method and observed with a transmission electron microscope. As a result, it was found that the polymer had a phase separation structure in which a polystyrene phase was uniformly dispersed in a polychloroprene phase. The polymer obtained from the above is presumed to be a styrene / chloroprene block copolymer having the following structure.

Example 3 Fully dried under reduced pressure, 100 ml equipped with a three-way cock
5.0 g of azo group-containing polystyrene synthesized in Reference Example 1, 80 ml of cyclohexane, and 15.0 g of chloroprene
Was charged. After fully degassing the ampoule and replacing with nitrogen,
The tube was sealed and polymerized at 60 ° C. for 22 hours. After the polymerization, the content of the ampoule was poured into a large amount of methanol to isolate the polymer. Thereafter, the polymer was dried by a conventional method to obtain 10.0 g of a polymer. After dissolving the obtained polymer in cyclohexane, chloroprene homopolymer and polystyrene were removed using acetone. The separated polymer was freeze-dried using benzene and analyzed. ^From the comparison of the peak intensities of the protons of the benzene ring of the styrene segment and the protons of the double bond portion in the chloroprene segment from ¹ H-NMR, the obtained polymer was found to have a number average molecular weight (Mn) of the styrene segment of 22,000 and chloroprene. The segment was found to be a copolymer having a number average molecular weight (Mn) of 149,000 (dispersion degree of molecular weight by GPC = 1.43). In FIG.
¹ H-NMR measurement results are shown. When the obtained polymer was cast using benzene, a transparent film having elasticity was obtained. The film was stained by a ruthenic acid staining method and observed with a transmission electron microscope. As a result, it was found that the polymer had a phase separation structure in which a polystyrene phase was uniformly dispersed in a polychloroprene phase. The polymer obtained from the above is presumed to be a styrene / chloroprene block copolymer having the following structure.

[Brief description of the drawings]

FIG. 1 shows the GPC of the polymers obtained in Examples 1 and 2.
FIG. 2 shows the results of ¹ H-NMR analysis of the polymers obtained in Examples 1 and 2.

Claims (2)

(57) [Claims] 1. The following general formula [I] (Wherein, R ¹ represents an alkyl group or an aryl group, R ²
Is an alkylene group having 1 to 18 carbon atoms, an alkylene group having 1 to 18 carbon atoms substituted with an aryl group and / or a cyano group, 1 to 1 carbon atoms substituted with an arylene group and / or a cyano group.
Represents at least one selected from 18 alkylene groups,
M represents a chloroprene residue, m and n each represent a degree of polymerization, and represent a positive integer. ) With a number average molecular weight of 10,0
00-500,000, the number average molecular weight of the styrene segment is 2,500-50,000, and the degree of dispersion (Mw / Mn) is 1.01-1.
A copolymer that is 50. 2. The following general formula [II] (Wherein, R ¹ represents an alkyl group or an aryl group, R ²
Is an alkylene group having 1 to 18 carbon atoms, an alkylene group having 1 to 18 carbon atoms substituted with an aryl group and / or a cyano group, 1 to 1 carbon atoms substituted with an arylene group and / or a cyano group.
Represents at least one selected from 18 alkylene groups,
m represents a degree of polymerization and represents a positive integer. The copolymer according to claim (1), which is obtained by polymerizing a chloroprene monomer using a polymer having one azo group in one molecular chain represented by the formula (1) as a polymerization initiator. Manufacturing method.