JP2973459B2 - Chloroprene polymer - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a chloroprene polymer having a xanthate group at the terminal of a molecular chain, and this polymer is formed into a molded product to form a belt, a hose, a wire, and a cable. It can be used in a wide range of fields such as coating.

[Prior Art] Conventionally, liquid rubbers have been produced in a complex system comprising a radical polymerization initiator such as BPO and AIBN, and a chain transfer agent such as mercaptans, alkyl xanthogen disulfide, and tetraalkylthiuram disulfide. In addition, in butadiene capable of ionic polymerization, molecular weight control by anionic polymerization and functionalization of molecular chain terminals have been carried out.
Chloroprene is a chlorine-containing monomer and anion polymerization is difficult. In the production of telechelic liquid rubber, a polymerization initiator having a functional group such as a hydroxyl group or a carboxyl group has been used. In this case, it is difficult to introduce a functional group into the terminal of all the polymers, and polymer molecules whose number of functional groups is usually 2 or less and 2 or more per molecule were mixed.

For the above reasons, photopolymerization using xylylenebis (dialkyldithiocarbamate) as a photopolymerization initiator has been studied in recent years, and has been found to be an effective polymerization means for functionalization of the terminal.

The above radical polymerization and the production of the terminal functionalized polymer by the photopolymerization method are reviewed by Bootevin (Ad-vances in Polymer Sc
ience), Vol. 94, Springer Verlag, Berlin, 1990
Year).

However, when chloroprene is polymerized by the carbamate-based initiator, the resulting polymer is brown. Furthermore,
The polymer has a drawback that the molecular weight distribution (w / n) of the polymer is large, a high molecular weight component having a molecular weight of tens of thousands exists, and there are various problems that the yield of the polymer is low. Accordingly, there has been no successful example of controlling the molecular weight of a chloroprene polymer by a conventional method using a carbamate-based initiator, and no study has been made on solving the problem of coloring of the polymer.

[Problems to be Solved by the Invention] As described above, it is difficult to produce a chloroprene polymer having only a low molecular weight component by conventional photopolymerization, and there is a problem that the polymer is colored. The present invention solves these problems at the same time, and provides a chloroprene polymer which is not colored and does not contain a high molecular weight component.

[Means for solving the problems] As a result of intensive studies to improve the above problems,
The following general formula [I] (Here, R represents an alkyl group having 1 to 18 carbon atoms.) Photopolymerization of chloroprene using an alkylxanthogen derivative represented by the following formula has almost no coloration, and was calculated from the charged catalyst and monomer. The following general formula [II] having a molecular weight close to the theoretical molecular weight (Where R represents an alkyl group having 1 to 18 carbon atoms;
Represents a chloroprene residue, and n represents a degree of polymerization. The present inventors have found that a polymer represented by the formula (1) is obtained, and have reached the present invention.

 Hereinafter, the present invention will be described in detail.

As the polymerization initiator that can be used in the present invention, the compounds represented by the above general formulas are suitably used, and the following compounds are exemplified, but this does not limit the present invention at all.

In order to eliminate the influence of impurities at the time of polymerization, when the compound is crystalline, it must be sufficiently purified by recrystallization. The polymerization solvent is not essential, and bulk polymerization can be performed. When a solvent is used, a solvent having a small chain transfer constant is suitably used as in the case of ordinary thermal radical polymerization, and examples thereof include benzene and toluene.

It is preferable to use a monomer from which the inhibitor has been completely removed and which has been purified by distillation. The polymerization temperature is not particularly limited, but is preferably 5 to 50 ° C, and more preferably 5 to 30 ° C. As the light irradiation device, any of a low-pressure mercury lamp and a high-pressure mercury lamp can be used without any problem.

The molecular weight can be easily adjusted by changing the charged molar ratio of the monomer / polymerization initiator. The molecular weight of the polymer of the present invention in a liquid state is approximately 15,000 or less,
It is preferable to adjust the molecular weight so that a polymer having a molecular weight of 1,000 to 15,000 is obtained. The polymerization is slightly affected by the charged amounts of the monomer and the initiator, or the monomer concentration. Therefore, it is necessary to determine the termination of the polymerization by monitoring changes in the initiator, the monomer, and the molecular weight during the polymerization.

To stop the polymerization, the light irradiation is stopped, a polymerization inhibitor such as BHT which is usually used is added, and the reaction solution is cooled if necessary. The polymer is isolated by pouring the reaction solution into a large amount of a poor solvent for the polymer such as methanol or hexane and isolating the polymer by a conventional method. Since all of the initiator is basically consumed, only a small amount of the initiator remains in the polymer. When it is desired to completely remove the unreacted initiator, the operation of dissolving the isolated polymer again in a solvent such as tetrahydrofuran, pouring the solution into acetone, and isolating the polymer by reprecipitation purification is repeated. Is preferred.

[Effects of the Invention] According to the present invention, it is possible to provide a low-molecular-weight chloroprene polymer having a photopolymerizable functional group at a terminal, which was conventionally difficult to produce.

[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.

Ushio Electric Co., Ltd., UM452 (450W)
A high-pressure mercury lamp and a lighting device UM-453B-A were used.

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) ¹ H- NMR Varian EM-360 NMR spectrometer Solvent: deuterated chloroform Internal standard: tetramethylsilane Measurement temperature: 25 ° C Determination of polymer end group H in double bond of chloroprene and initiator residue (alkoxy group) The degree of polymerization was calculated from the integral ratio of H in the methylene or methyl group in the sample).

Example 1 0.7196 g of xylylenebis (methylxanthate) and 50.0 m of benzene in a 100 ml Pyrex glass ampoule
l, 9.71 g of chloroprene were charged, and after sufficiently degassing, the ampoule was sealed. The above ampoule was fixed at a distance of 80 mm from a high-pressure mercury lamp while maintaining a constant-temperature water bath at 30 ° C., and irradiated with ultraviolet rays for 17 hours without stirring. After the polymerization, the ampule was opened and the content was poured into a large amount of methanol to isolate the polymer. The resulting polymer is a pale yellow viscous liquid,
GPC measurement results (GPC measurement results are shown in FIG. 1), the number average molecular weight (n) was 2,300, and the molecular weight determined from terminal group quantification by ¹ H-NMR was 2,740, a molecular weight close to the theoretical value (2,560) Had. In addition, HPLC (high performance liquid chromatography) analysis showed that the initiator was completely consumed during the polymerization. From the above results, it is estimated that the obtained polymer has the following structure.

(Wherein, M represents a chloroprene residues.) Analysis ^{1 H-NMR (60MHz, CDCl} 3) δ2.33 (multiplet, -C H 2 -CH = CCl-C H 2 -) δ4.05 (Singlet, −C ₆ H ₄ −p−C H ₂ −) δ 4.15, 4.30 (singlet, singlet, −C (S) O−C H
₃ −) δ 5.45 (broad, −C H = CCl−) δ 7.05 (broad, −C ₆ H ₄ —CH ₂ −) Example 2 0.7828 g of xylylene bis (ethyl xanthate) in a 100 ml Pyrex glass ampule. , Benzene 50.0m
l, 9.07 g of chloroprene were charged, and after sufficiently degassing, the ampoule was sealed. The above ampoule was fixed at a distance of 80 mm from a high-pressure mercury lamp while maintaining a constant-temperature water bath at 30 ° C., and irradiated with ultraviolet rays for 17 hours without stirring. After the polymerization, the ampule was opened and the content was poured into a large amount of methanol to isolate the polymer. The obtained polymer was a pale yellow viscous liquid (yield 67%). As a result of analyzing this polymer by GPC (the GPC measurement result is shown in FIG. 1), the number average molecular weight (n) was
The molecular weight determined from the terminal group quantification by 1,920 and ¹ H-NMR is 3,3.
It was 370 and had a molecular weight close to the theoretical value (2,970). The polymer was analyzed by ¹ H-NMR (FIG. 2 shows ¹ H-N
From the results of the measurement of MR), it is estimated to have the following structure. In addition, HPLC analysis showed that all the initiator was consumed during the polymerization.

From the above results, it is estimated that the obtained polymer has the following structure.

(Wherein, M represents a chloroprene residues.) Analysis ^{1 H-NMR (60MHz, CDCl} 3) δ1.0-1.4 (broad, -CS-O-CH 2 C H 2 C H 3) δ2.30 ( _{multiplet, -C H 2 -CH = CCl} -C H 2 -) δ4.30 (singlet, -C 6 H 4 -p-C H 2 -) δ4.50 (triplet, -O-C H 2 CH 2 CH ₃₋ ) δ 5.45 (broad, −C H = CCl−) δ 7.0−7.2 (broad, −C ₆ H ₄ —CH ₂ −) Example 3 100 ml of Pyrex glass ampule was added to xylylenebis (n-propylxan). 0.8463 g, benzene 5
0.0 ml and chloroprene 10.0.1657 g were charged, and after sufficient degassing, the ampoule was sealed. The above ampoule was fixed at a distance of 80 mm from a high-pressure mercury lamp while maintaining a constant-temperature water bath at 30 ° C., and irradiated with ultraviolet rays for 17 hours without stirring. After the polymerization, the ampule was opened and the content was poured into a large amount of methanol to isolate the polymer. The obtained polymer was a pale yellow viscous liquid (yield 79%). The polymer was analyzed by GPC. As a result, the number average molecular weight (n) was 2,240, and the molecular weight determined from terminal group quantification by ¹ H-NMR was 3,460, which was the theoretical value (3,10
It had a molecular weight close to 0). In addition, HPLC analysis showed that all the initiator was consumed during the polymerization.

From the above results, it is estimated that the obtained polymer has the following structure.

_{* O-n-C 3 H} 7 ( where, M represents a chloroprene residues.) Analysis ^{1 H-NMR (60MHz, CDCl} 3) δ0.8-1.2 (broad, -CS-O-CH 2 C H _{2 C H 3) δ2.33 (multiplet} , -C H 2 -CH = CCl-C H 2 -) δ4.30 (singlet, -C 6 H 4 -p-C H 2 -) δ4.60 (triplet, _{-O-C H 2 CH 2 CH} 3) δ5.45 (broad, -C H = CCl-) δ7.0-7.2 (broad, -C 6 H 4 -CH 2 -) Pyrex glass of example 4 500 ml 1.3039 g of xylene bis (methyl xanthate), 350.0 ml of benzene,
After charging 100.0 g of chloroprene and performing sufficient degassing,
The ampoule was sealed. The above ampoule was fixed at a distance of 100 mm from a high-pressure mercury lamp while maintaining a constant-temperature water bath at 15 ° C., and irradiated with ultraviolet rays for 20 hours without stirring. After the polymerization, the ampule was opened and the content was poured into a large amount of methanol to isolate the polymer. The obtained polymer was a pale yellow viscous liquid (yield 60%). As a result of analyzing the polymer by GPC, the number average molecular weight (n) was 11,000, which was close to the theoretical value (13,500).

From the above results, it is presumed that this polymer has the following structure.

* OCH ₃ (where, M represents a chloroprene residues.) Analysis ^{1 H-NMR (60MHz, CDCl} 3) δ2.33 (multiplet, -C H 2 -CH = CCl-C H 2 -) δ4.15 , 4.30 (doublet, -C (S ) O-C H 3) δ4.05 (singlet, -C 6 H 4 -p-C H 2 -) δ5.43 (broad, -C H = CCl-) δ7. 0-7.2 (broad, -C ₆ H ₄ -CH _2- ) Comparative Example 1 0.9036 g of xylylenebis (diethyldithiocarbamate), 50.0 ml of benzene, and 9.663 g of chloroprene were charged into a 100 ml Pyrex glass ampoule and sufficiently degassed. After performing, the ampoule was sealed. The above ampoule was fixed at a distance of 80 mm from a high-pressure mercury lamp while maintaining a constant-temperature water bath at 30 ° C., and irradiated with ultraviolet rays for 17 hours without stirring. After the polymerization, the ampule was opened and the content was poured into a large amount of methanol to isolate the polymer. The obtained polymer was a pale yellow viscous liquid (yield 59%). As a result of analyzing the polymer by GPC (the GPC measurement result is shown in FIG. 1), the number average molecular weight (n) was 13,300, which was 6 times or more the theoretical value (2,210) calculated from the charge. And it was difficult to control the molecular weight. Further, the obtained polymer was colored dark brown.

Comparative Example 2 A glass ampoule made of Pyrex was charged with 0.2089 g of xylylenebis (diethyldithiocarbamate), 50.0 ml of benzene, and 10.0 g of chloroprene. After sufficient degassing, the ampoule was sealed. The ampoule was fixed at a distance of 80 mm from a high-pressure mercury lamp while maintaining a constant-temperature water bath at 15 ° C., and irradiated with ultraviolet light for 22 hours without stirring. After the polymerization, the ampule was opened and the content was poured into a large amount of methanol to isolate the polymer. The obtained polymer was a pale yellow viscous liquid (yield 54%). As a result of analyzing this polymer by GPC (the GPC measurement result is shown in FIG. 1), the number average molecular weight (n) was 2,460, and the theoretical value (1
0,500), and it was difficult to control the molecular weight. Further, the obtained polymer was colored dark brown.

[Brief description of the drawings]

FIG. 1 shows the GPC elution curves of the polymers obtained in Example 1 (1 in the figure), Example 2 (2 in the figure), Comparative Example 1 (3 in the figure), and Comparative Example 2 (4 in the figure). Express. FIG. 2 shows ¹ H-NMR of the polymer obtained in Example 2.

Claims (1)

(57) [Claims] 1. The following general formula [I] (Where R represents an alkyl group having 1 to 18 carbon atoms;
Represents a chloroprene residue, and n represents a degree of polymerization. ) A chloroprene polymer having a number average molecular weight (n) of 1,000 to 15,000.