JPH0345610A - Production of polychloroprene - Google Patents

Abstract

PURPOSE:To produce polychloroprene having a high mol.wt. and a low degree of dechlorination in high yields by using a specified transition metal halide as a polymerization catalyst. CONSTITUTION:Polychloroprene is obtained by polymerizing chloroprene by using a metal halide of the formula: MXn (wherein M is a transition metal selected from among group IV-b, Vb and VIb metals, desirably Ti, Zr, V, Nb, Ta, Cr, W or the like, X is a halogen atom, and n is the number of the halogen atoms), e.g. VCl3, as a catalyst in optionally a fully dehydrated chlorinated aliphatic hydrocarbon solvent in an inert atmosphere desirably at 0 deg.C or below, more desirably at -30 to -80 deg.C for usually 4-20hr. The amount of the catalyst used is 10<-6>-10<-2>, desirably 10<-5>-10<-4> in terms of a molar ratio to the chloroprene.

Description

[Detailed Description of the Invention] [Industrial Field of Application] Chloroprene, which is industrially produced by emulsion polymerization, is used in the machinery and automobile industries, etc., for belts, hoses, various molded bodies, coating materials for wires and cables, and construction materials. Used in a wide range of applications including sealants, gaskets, and adhesives. Therefore, it is thought that polychloroprene produced by the novel polymerization method of the present invention can also be used in the various fields mentioned above.

[Prior Art and Problems to be Solved by the Invention] Polychloroprene is currently produced by an emulsion polymerization method.

However, the emulsion polymerization method has a problem in that the molecular structure of the polymer cannot be sufficiently controlled. Therefore, in order to control the microstructure, studies have been conducted on ionic polymerization of chloroprene.

For example, anionic polymerization of chloroprene has been investigated using the catalyst system described below.

investigated polymerization using alkyllithium systems (for example, Vysokollol, 5oyed, Vol. 6-7, p. 1294, 1964). However, in this catalyst system, polymerization stops at a monomer conversion rate of 7 to 9%.

Krasnoselskaya et al.
9(4), p. 851, 1967), alkyllithium-lithium iodide-alkylmagnesium systems (e.g.
Sokoaol, 5oyed,), Volumes 6-9, 1
637 pages, 1964). With these catalyst systems, the polymer yield increased to 30-80%, but
The resulting polymer is insoluble.

This catalyst system has also been studied by Yerushalimsky (for example, Dokrady Academy Nauk,
dy Akade*ii Nauk), 5SSR Magazine),
169-1, p. 114, 1961).

In addition, the alkylmagnesium-alkylmagnesium iodide system was investigated by Guzman (for example, Vysok
oa+ol, 5oyed, ) magazine, No. A-19(12)
Vol. 2793, 1977). However, this catalyst system had a problem in that the catalyst was deactivated due to elimination of chlorine from chloroprene.

Bosniakov studied polymerization using modified Ziegler-type catalysts (for example, Alyumyansky Kimicheskia Jurnal (A "1Khim, Zh"),
26-8, p. 696, 1973). However, the product is a gel-like poly→- which is insoluble in the solvent.

In addition, a cobalt alkyl aluminum naphthenate system is being investigated by Kalyzhnaia (Azervezhanskii Kimicheskii Jurnal).
b, Khim, Zh,), Vol. 3, p. 89, 1967
Year). The yield of the polymer was as small as 14% at most, and no change in the yield was observed as the polymerization time was extended, resulting in the problem of deactivation of the catalyst.

In cationic polymerization, there are studies using Lewis acids by Klebansky et al., but the product is a low molecular weight liquid (lzv, Akad, Nauk, Ara+, SSR,
Khlm,.

(Nauk Magazine, Vol. 13, p. 147, 1960) [Means for Solving the Problems] As mentioned above, the ionic polymerization catalysts that have been conventionally studied are:
Deactivation of the catalyst by elimination of chlorine in the chloroprene monomer,
It has various problems, such as low catalytic activity and difficulty in increasing the molecular weight, easy formation of gel-like polymers that are insoluble in solvents, and low yields.

As a result of intensive studies to solve the above-mentioned problems, we found that chloroprene has the following general formula (1)% formula (1) (Kokote, M is selected from groups IVb, Vb and VIb of the periodic table) X represents a transition metal such as F, Cl, Br
and l represents a halogen atom, and n represents the total number of halogen atoms). By polymerizing the metal halide as a polymerization catalyst, the polymer has a high molecular weight and a small tendency to eliminate chlorine as a monomer. A new method for polymerizing roloprene was invented.

The metal halide catalyst used in the present invention is listed in Periodic Table 1.
Halides of metals of group Vb, group Vb, and group VIb can be used, but preferably Ti of group IVb is used.
(titanium), Zr (zirconium), V (vanadium) of the VB group, Nb (obium), Ta (tantalum), and ■
It is preferable to use halides of metals belonging to Group B, Cr (chromium) and W (tungsten), such as titanium tetrachloride, titanium tetrabromide, titanium tetraiodide, titanium tetrafluoride, zirconium tetrachloride, and tetrabromide. Zirconium, zirconium tetraiodide, zirconium tetrafluoride, vanadium trichloride,
Vanadium tribromide, vanadium triiodide, vanadium trifluoride, vanadium pentachloride, vanadium pentabromide, vanadium pentaiodide, vanadium pentafluoride, niobium pentachloride, niobium pentabromide, niobium pentaiodide, pentafluoride Niobium oxide, tantalum pentachloride, tantalum pentabromide, tantalum pentaiodide, tantalum pentafluoride, chromium trichloride, chromium tribromide, chromium triiodide, chromium trifluoride, tungsten hexachloride, tungsten hexabromide, Examples include tungsten hexaiodide and tungsten hexafluoride, and more preferred are vanadium halides, tantalum halides, and tungsten hexafluorides, and it is preferable to use those with as high purity as possible.

It is preferable to use the monomer chlorobrene that has been sufficiently dehydrated, and it is also preferable to use one that has reduced impurities as much as possible. Therefore, after the monomer used in the present invention is distilled, it is necessary to dehydrate it using a general dehydration method using calcium hydride or the like. More preferably, the dehydrated monomer is dehydrated again using a catalyst.

During the polymerization of chlorobrene, the amount of metal halide to be charged to chlorobrene is in a molar ratio of 10-8 to 10''-2.
(Number of moles of catalyst/Number of moles of monomer), and more preferably 10 to 10-' (Number of moles of catalyst/Number of moles of monomer), but this does not limit the present invention in any way. The charging ratio can be arbitrarily set in relation to the molecular weight of the chloroprene polymer to be obtained.

A solvent is not necessarily required in the polymerization method according to the invention. However, solution polymerization can likewise be carried out without any problems. As the solvent to be removed, any solvent can be used as long as it does not react with the catalyst. Considering the solubility of polychloroprene, a halogenated aliphatic hydrocarbon solvent is preferably used, and furthermore, a solvent generally used in ionic polymerization is preferably used. Solvents that can be used in the present invention include dichloromethane, 1.1-dichloroethane, 1,2-dichloroethane, 1chloroethane, 1chloropropane, chloroform, 1.1.2.2-
Examples include chlorinated aliphatic hydrocarbons such as tetrachloroethane, but this does not limit usable solvents. In addition to the chlorinated solvent, iodinated aliphatic hydrocarbons, brominated aliphatic hydrocarbons, etc. can be used. It is necessary to use a solvent that has been sufficiently dehydrated by a conventional method, preferably one that has been dehydrated again using the metal halide catalyst used before polymerization. Additionally, some metal halides are soluble in chlorinated aliphatic hydrocarbons, so it is best to check the solubility of the metal catalyst in the solvent in advance and set the polymerization system to be as homogeneous as possible. preferable.

The amount of solvent is usually 0 per mole of chloroprene monomer.
It is preferable to use m1 to 100 m1, but it can be varied.

The polymerization temperature is preferably 0° C. or lower in order to prevent radical polymerization of the chloroprene monomer. There is no problem as long as the polymerization temperature is 0°C or lower, but it is more preferably between -30°C and
Perform at -80°C.

The polymerization time varies depending on the activity of the catalyst, but is usually 4 to 20 hours.

[Effects of the Invention] According to the present invention, it is possible to provide a novel method for polymerizing polychloroprene with high yield, high molecular weight, and a small amount of dechlorination and chlorine.

[Examples] Hereinafter, the present invention will be explained in more detail with reference to Examples, but these are not intended to limit the present invention in any way.

Example 1 A 100m1 tank equipped with a three-way cock and a stirrer
The flask was connected to a vacuum line, thoroughly degassed and dried, and then replaced with nitrogen. removing the reactor from the vacuum line;
0.699 mmol of vanadium trichloride was charged under a nitrogen atmosphere. The reactor was again connected to the nitrogen line and degassed. 1,2- Dehydrated with calcium hydride and degassed
32.8 grams of dichloroethane was charged to the reactor via the vacuum line. Next, under stirring, 72.0 g of chlorobrene monomer, which had been dehydrated with calcium hydride and degassed, was added to a 100 ml solution containing 3 g of vanadium trichloride.
0 flask via a vacuum line, and dehydrated while stirring.

This chloroprene monomer was charged into the reactor via a vacuum line to initiate polymerization. Thereafter, polymerization was carried out at −28° C. for 10 hours, the contents were poured into methanol, and the polymer was separated by precipitation. Dissolve the polymer in tetrahydrofuran,
It was poured into a mixed solution of methanol/water (volume ratio 1/1) and reprecipitated. Furthermore, the tetrahydrofuran solution of the polymer was poured into water again to cause reprecipitation. After performing this operation twice, finally, a tetrahydrofuran solution of the polymer was poured into methanol and reprecipitated to isolate the polymer. The isolated polymer was dissolved in benzene, freeze-dried, and then analyzed.

Gel permeation chromatography analysis revealed that the produced polymer was a rubbery material with a molecular weight (LogMw) distribution of 3 to 5. Further, the chlorine content of the produced polymer was 39%, which was close to the theoretical value and the tendency for chlorine to be eliminated was very small. As a result of DSC measurement, the glass transition temperature is -44,
At 3°C, it showed a higher value than polychloroprene usually obtained by radical polymerization. Further, the catalytic activity expressed as the amount of polymer produced per unit catalyst mole was 13,000 (gram 1 mole).

Example 2 A 100m1 tank equipped with a three-way cock and a stirrer
The flask was connected to a vacuum line, thoroughly degassed and dried, and then replaced with nitrogen. removing the reactor from the vacuum line;
0.419 mmol of tantalum pentachloride was charged under a nitrogen atmosphere. The reactor was again connected to the nitrogen line and degassed. 29.5 grams of 1,2-dichloroethane, dehydrated with calcium hydride and degassed, was charged to the reactor via a vacuum line. Next, under stirring, 37.3 grams of chloroprene monomer that had been dehydrated with calcium hydride and degassed was charged into a 100 ml flask containing 1 gram of tantalum pentachloride via a vacuum line, and dehydrated under stirring. did. This chloroprene monomer was charged into the reactor via a vacuum line to initiate polymerization. Thereafter, polymerization was carried out at -28°C for 20 hours,
The contents were poured into methanol and the polymer was separated by precipitation. The polymer was dissolved in tetrahydrofuran, poured into a mixed solution of methanol/water (volume ratio 1/1), and reprecipitated. Furthermore, the tetrahydrofuran solution of the polymer was poured into water again to cause reprecipitation. After performing this operation twice, finally, a tetrahydrofuran solution of the polymer was poured into methanol and reprecipitated to isolate the polymer. The isolated polymer was dissolved in benzene, freeze-dried, and then analyzed. Gel permeation chromatography analysis revealed that the produced polymer was a semi-solid with a molecular weight (L-ogMw) distribution of 3 to 4. Furthermore, the chlorine content of the produced polymer was 38%, which was close to the theoretical value and the tendency for chlorine to be eliminated was very small. As a result of DSC measurement, the glass transition temperature is -46,
At 0°C, it showed a higher value than polychloroprene (glass transition point -49°C), which is usually obtained by radical polymerization.

Further, the catalytic activity expressed as the amount of polymer produced per unit catalyst mole was 15,000 (gram 1 mole).

Example 3 10. A three-way cock was attached and a stirrer was inserted. An Oml 1-day flask was connected to a vacuum line, thoroughly degassed and dried, and then replaced with nitrogen. The reactor was removed from the vacuum line and charged with 0.630 mmol of tungsten hexachloride under a nitrogen atmosphere. The reactor was again connected to the nitrogen line and degassed. Dehydrated with calcium hydride and degassed 1,
26.7 grams of 2-dichloroethane was charged to the reactor via the vacuum line. Next, under stirring, 43.4 g of chloroprene monomer, which had been dehydrated with calcium hydride and degassed, was placed in a 100 m
The mixture was charged into 10 flasks using a vacuum line, and dehydrated with stirring. This chloroprene monomer was charged into the reactor via a vacuum line to initiate polymerization. Thereafter, polymerization was carried out at −28° C. for 20 hours, the contents were poured into methanol, and the polymer was separated by precipitation. The polymer was dissolved in tetrahydrofuran, poured into a mixed solution of methanol/water (volume ratio 1/1), and reprecipitated. Furthermore, the tetrahydrofuran solution of the polymer was poured into water again to cause reprecipitation. After performing this operation twice,
Finally, a tetrahydrofuran solution of the polymer was poured into methanol and reprecipitated to isolate the polymer. The isolated polymer was dissolved in benzene, freeze-dried, and then analyzed.

Gel permeation chromatography analysis revealed that the produced polymer was an elastic body with a molecular ffi (LogMw) distribution of 4 to 6. In addition, the amount of chlorine in the generated polymer was 3
It was 9%, which was close to the theoretical value, and the tendency for chlorine desorption was very small. The glass transition temperature was -36℃ as a result of DSC measurement, compared to polychloroprene usually obtained by radical polymerization.
It showed a high value. In addition, the catalytic activity expressed as a polymer generator per unit catalyst mole is 46000 (gram 1 mole)
Met.

[Brief explanation of drawings]

1 and 2 show GPC elution curves of the polymers obtained in Example 1 and Example 3.

Claims (1)

[Claims] (1) Chloroprene is expressed by the following general formula (1) MX_n(
1) (Here, M represents a transition metal selected from groups IVb, Vb, and VIb of the periodic table, and X represents F, Cl, Br, and I
1. A method for producing polychloroprene, which comprises polymerizing a metal halide represented by a halogen atom selected from the following, where n represents the total number of halogen atoms, as a polymerization catalyst.