DE1420756B2 - Process for the homopolymerization or copolymerization of halogen olefins - Google Patents

Description

The invention relates to a process for the homo- or mixed polymerization of halogen olefins general formula

(R ₁ ) (R ₂ ) C = C (R ₃ ) (Hai)

in which R ₁ , R ₂ and R _{3 are} hydrogen atoms, alkyl radicals or halogen atoms, with the aid of boron trialkyls as catalysts. The object of the invention is to enable the polymerization to be carried out effectively at low temperatures under atmospheric pressure.

It is known from the laid-out documents of Belgian patents 560 624, 562 433 and 562 701 that compounds containing the group> C - C < can be polymerized and / or copolymerized at low temperatures and under atmospheric pressure in the presence of boron triolkyls. The polymers and / or copolymers obtained according to these publications have improved mechanical properties and an increased degree of crystallinity.

In U.S. Patent 2,840,551, there is the possibility mentions polymerizing olefins in the presence of a catalytic system which consists of a boron trialkyl compound and a salt of a metal of Groups IVa, Va and VIII of the Periodic System, for example a metal azide.

It has now been found that the activity of the boron trialkyls used as catalysts for the polymerization and / or copolymerization of halogen olefins of the formula given can increase the addition of suitable activators to a noticeable extent.

The inventive method for the polymerization or copolymerization of halogen olefins the general formula given above with the help of boron trialkyls as catalysts is thereby characterized in that the polymerization in the presence of 0.3 to 3%, based on the weight of the monomers, organic peroxides or azodinitriles is carried out at low temperatures.

The organic peroxide used is, for example, benzoyl peroxide, lauroyl peroxide or 2,4-dichlorobenzoyl peroxide and as azodinitrile z. B. the azodiisobutyronitrile.

The amount of boron trialkyl to be used is advantageously 0.1 to 3 percent by weight, based on the amount of monomer used.

The polymerization can be carried out in bulk or in the presence of an inert organic medium will. Since the boron trialkyls are not particularly sensitive to water, the polymerization can be carried out also in an aqueous medium by known polymerization methods, such as the emulsion or Suspension polymerization. Boron triethyl is preferably chosen from among the boron trialkyls or boron tri (n-butyl).

The catalytic system used according to the invention allows the polymerization and / or Interpolymerization at unusually low temperatures and still with considerable yields perform. The polymers and / or copolymers obtained according to the process generally have an increased degree of crystallinity and improved mechanical properties compared to the Polymers and copolymers, such as those produced by the previously customary processes.

In the "Journal of Polymer Science", Vol. 28 (1958), pp. 227 to 229, the activation of organic boron derivatives by oxygen, hydrogen peroxide and metal oxides in catalytic polymerisation of vinyl monomers. But it could not be concluded from this that the activation of boron trialkyls through organic peroxides or azodinitriles in the polymerization of halogen olefins would be favored.

In addition, the following comparative tests were used for this purpose carried out:

After purging the air with a stream of nitrogen, 1400 g of vinyl chloride and 100 g of methanol were introduced into a flask equipped with a stirrer, a heat-insulating jacket and a nitrogen inlet, while maintaining a temperature of -40 ° C. The table is then put 3.67 • 10 ^"3 g-mole Bortriäthyl and 7.34 x 10 ~ ³ g-mol of a peroxide added. The temperature was kept at ⁰ C -4o and determined the yield of produced polyvinyl chloride. Are the yield of polymer with the peroxide used in each case:

". attempt
²⁵ No. Type of peroxide Educated
Polymer
g / hour 1
2
30 3
4th
5 tert-butyl hydroperoxide
tert-butyl peracetate
Cumene hydroperoxide
tert-butyl perlaurate
Hydrogen peroxide 44
43
41
37
0.7 ^v

Experiment no. 5 clearly shows that the boron trialkyl — H ₂ O _{2 system} did not bring about the polymerization of the vinyl chloride at low temperature, in contrast to the catalytic systems of experiments nos. 1 to 4.

Comparative example

In a glass flask of 11 with three tube inserts, provided with stirrer, thermal insulation and a nitrogen line is added after expulsion of the air by means of a nitrogen stream at a temperature of -25 ⁰ C held 500 g vinyl chloride and 50 g of η-hexane. 0.75 g of boron tri (n-butyl) are added. The temperature is kept at -25 ° C. and after 2 hours of polymerization 27 g of polyvinyl chloride are obtained.

·

example 1

The procedure is as in the comparative example, but 1 g of 2,4-dichlorobenzoyl peroxide is added to the reaction medium added. After 2 hours of polymerization at -25 ° C., 36 g of polyvinyl chloride are obtained.

Example 2

The procedure is as in the comparative example, but 1 g of azodiisobutyronitrile is added to the reaction medium added. After 2 hours of polymerization at -25 ° C., 42 g of polyvinyl chloride are obtained.

Claims (1)

Claim: Process for the homopolymerization or copolymerization of halogen olefins of the general formula (R ₁ ) (R ₂ ) C = C (R ₃ ) (Hai)
in which R ₁ , R ₂ and R _{3 are} hydrogen atoms, alkyl mean residues or halogen atoms, with the help of boron trialkyls as catalysts, thereby characterized in that the polymerization in the presence of 0.3 to 3%, based on the Weight of the monomers, organic peroxides or azodinitriles at low temperatures is carried out.