CS202936B1 - Process for the starting polymerization of vinylic monomers - Google Patents

Description

The invention relates to a process for initiating polymerization of vinyl monomers, in particular styrene, methyl methacrylate, acrylonitrile and vinyl acetate at temperatures of 0 ° C to 100 ° C in the presence of an initiator system under an inert atmosphere.

A number of useful oxidation reduction initiation systems are described in the literature as well as in the patents, in which the oxidizing component is peroxides and hydroperoxides such as tert-butyl hydroperoxide, cumyl hydroperoxide and a thiourea reducing agent, or symmetrical diethyl and diphenylthioureas. In British patent no. No. 715,382 discloses the polymerization of acrylonitrile in an inert atmosphere at room temperature, wherein the initiation system consists of tert-butyl hydroperoxide and thiourea. British Patent No. 797 953 discloses an initiation system consisting of hydrogen peroxide and 1,3 diphenylthiourea, respectively. thiooxalic acid derivatives. However, the described systems have the disadvantage that they are only slightly more effective than the initiation system consisting of a single tert-butyl hydroperoxide alone. It is an object of the present invention to provide polymerization of vinyl monomers in an inert atmosphere in the presence of a more efficient oxidation-reduction initiation system,

20233b

These disadvantages are eliminated by the method of initiating the polymerization of vinyl monomers, in particular styrene, methyl methacrylate, acrylonitrile and vinyl acetate, in an inert atmosphere at temperatures of 0 ° C to 100 ° C, preferably at 20 ° C to 70 ° C according to the invention. the polymerization is carried out in the presence of oxidačnoredukčného initiator system, wherein the oxidizing component is t-butyl hydroperoxide in a concentration of 1.10 ^'2 to 32. 10 ^-2 mol. ^11, based on the monomer and the reducing component, is a substituted thiourea of the general formula

OS

II II

R — C — NH — C — R 'where R is —CsH5, —CeHa — OCHs, —CeHu — OC2H5, —Csl-U-Halogen, CsHa — NH2, —Csl-Lt — COOH, - (CH2) n CH3 where π = 0 to 17

R 1 is —NH2, —NHCH3, —N (CH3) of —NHC2H5, —N (C2H5) 2, —NHC3H7, —NHC4H11, —NHCeHs, —NHCsHi-Halogen,

CIT2CH2 / \ —N O \ /

CH 2 CH 2 at a concentration of 0.5.10 ^-2 to 3.10 ² mol. ^11, based on the monomer, wherein the molar ratio of oxidizing component to reducing component is 1 to 1 to 16 to 1, preferably 2 to 1 to 6 to 1.

In particular, the advantages of the method of initiation according to the invention lie in several times higher efficiency than in the prior art oxidation-reduction initiation systems. A further advantage is that for the different polar monomers, the desired solubility of the plungers in the monomer can be achieved by the appropriate choice of substituents R and R '. Another advantage is a small influence on the rate of polymerization and hence on product properties, by changing the thermal regime, as well as the antioxidant action of thiourea residues in the prepared polymer. The present method of initiation can be used in addition to block also in solution, emulsion and suspension polymerization of vinyl monomers. The advantages of the present method of polymerization initiation are also evident from the following examples.

Example 1

A solution of tert-butyl hydroperoxide in styrene at 4.7 was prepared. IO ^-2 mol. I ^-1 vial is charged with a quantity of thiourea, following the addition of 5 ml of tert-butyl hydroperoxide in styrene, the concentration of thiourea 2,69.10 ^-2 mol. I “ ¹ . The molar ratio of thiourea to tert-butyl hydroperoxide was 1: 1.75. 5 ml of a solution of tert-butyl hydroperoxide in styrene was added to the weighed thioureas in vials, the vials were bubbled through with purified N2 and sealed. The polymerization was carried out for 1 hour. at 70 ° C. After 1 hour the samples were cooled, polystyrene precipitated quantitatively with methanol, filtered and after drying to constants, the conversion was calculated -% K. Polymerization without thioureas, conversion -% Ko was also performed. The ratio of% K to ° / o Ko = α indicates an increase in hourly conversion due to thioureas. % conversion per hour and values and are shown in Table 1.

Example 2

The polymerization of styrene with selected substituted thioureas was carried out under the same conditions as in Example 1, but at different temperatures. At 20 ° C for 2 hours, at 40 ° C, 60 ° C and 70 ° C for 1 hour. and at 80 ° C for 0.5 hour.

Conversions and a values are shown in Table 2.

Example 3

At the same concentrations of tert-butyl hydroperoxide and thioureas as described in Example 1, methyl acrylate was polymerized. The polymer isolation and the conversion determination were carried out as in Example 1. The conversions and values and are shown in Table 1. 3. Polymerization was carried out for 1 hour. at 40 and 70 ° C.

Example 4

Using the same concentrations of tert-butyl hydroperoxide and thioureas as in Example 1, polymerization of acrylonitrile was performed at 22 ° C in block. During the polymerization, polyacrylonitrile precipitated as a white powder, which was isolated by filtration and dried to constant weight after washing with methanol. At a given temperature in the presence of thioureas, polymerization was not observed within 6 hours.

As in the previous cases, acrylonitrile was not polymerized in the presence of air. After the introduction of the inert atmosphere, polymerization begins immediately.

In the case of 1-benzoyl-3-p-chlorophenylthiourea and 1-benzoyl-3-phenylthiourea, the polymerization had a turbulent, uncontrollable course.

Using 1-benzoylthiourea after% hour, the conversion was 32%; with 1-benzyl-3-n-propylthiourea after% hr. the conversion was 11.26% and with 1-benzoyl-3,3-diethyloxythiourea after% hr. 2.5 ° / o conversions. Example 5

At the same concentrations of tert-butyl hydroperoxide and thioureas as in Example 1, vinyl acetate polymerizations were carried out at 44 ° C for 2 hours. The conversion was determined by evaporating the monomer under vacuum to constant weight. The conversion of vinyl acetate with tert-butyl hydroperoxide alone under the stated conditions was less than 0.1% after 2 hours. The vinyl acetate conversions using different thioureas are shown in Table 4.

Example 6

Styrene was polymerized at 40 ° C for 1 hour, in sealed vials in an N 2 atmosphere. The tert-butyl hydroperoxide concentration was 4.70. IO ^-2 mol. Γ ¹ . Four substituted thioureas were used as reducing agents. Their concentrations, together with other results, are shown in Table 5.

Example 7

Block polymerization of acrylonitrile was performed under conditions as in Example 4 but at 2 ° C. The same thioureas were used as the reducing agent at 22 ° C. The following conversions were achieved: At 48 ° C, acrylic vinyl polymerization was not observed after 48 hours. using tert-butyl hydroperoxide alone.

The present method of initiating polymerization of vinyl monomers can be utilized in all plants producing polymer from monomer in an inert atmosphere. It is especially suitable for cases where it is necessary to work at low temperature.

Table 1

No. Thiourea Conversion (% / h) a

1 l-acetyl-3-étoxyfenyltio- urea 19.69 '11, 3 2 l-Stearyl-3-etoxyfenyltio- urea 18.35 10.5 3 l-benzoyl-3,3-dietylC'Xytio- urea 15.18 8.7 4 l-benzoyl-3-fenyltiomioeo'vina 14.90 8.5 5 l-acetylthiourea 14.38 8.2 6 (tert-butylhydro- 1.75 1

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202938. Table 3 /

C. Thiourea 40 ° C 70 ° C

% K and % K and First l-benzoyl-3-n-propyl thiourea - - 100 37.0 Second l-benzoyl-3-phenyl thiourea 23.6 71.5 82.7 30.6 Third l-benzoyl-3-parachlórfenyl- tiomiočovina 20.5 58.6 72.2 26.8 4th 1-benzoyltiioanočovina 10.5 29.9 39.6 14.7 5th l-ethoxybenzoyl-3,3-diethyl- oxytiomočivna - -. 19.2 7.2 6th l-benzoyl-3,3-dietyloxy- tiomločovina - - ' 10.7 3.9 7th l-benzoyl-3,3-dietyltio- míočovina - - 15.3 5.6 8 (tert-butylhydro- 0.35 1 2.71 1

peroxide)

Table 4.

No. Thiourea Conversion (i% / 2 hours)

First l-benzoyl-3-n-propyítio- urea 31.6 Second 1-benzoylfiomočovina 22.6 Third l-benzioyl-3-phenyl thiourea 4.2 4th l-benzoyl-3-p-chlorophenyl thiourea 3.4 5th l-benzoyl-3,3-dietyloxytio- urea 3.3 6th 1-Benzoyl-1,3,3-diethylthio- 0.8

urea

Table 5

Conc. (Mol. Conversion% a .1 ¹ ) - 10 ²

C.

thiourea

First 1-benzoyl thiourea 2.69 3.90 26.3 1.34 3.55 23.7 0.67 3.53 23.5 Second l-benzoyl-3-n-propylthio 2.69 10,30 68.9 urea 1.34 8.73 58.2 0.67 6.96 46.5 Third l-benzoyl-3-p-chlorophenyl 2.69 8.08 53.9 thiourea 1.34 7.80 52.0 0.67 4.60 31.0 4. l-benzoyl-3-fenyltiomoičovina 2.69 - - 1.34 7.55 50.30 0.67 5.77 38.47 T a b u 1 'to a 6 c. thiourea Polymerization time Conversion% First 1-benzoyltlomiočovina 3 hours 2.19 Second 1-Benzoyl-3-n-propylthio- 3 hours 1.80 urea Third l-benzloyl-3-p-chlorophenyl 2 hrs 2.11 thiourea 4th l-benzoyl-3-fenyltiomoičovina 2 hlod. 2.76

OBJECT OF THE INVENTION

Claims (2)

Method for initiating polymerization of vinyl monomers, in particular styrene, methyl methacrylate, acrylonitrile and vinyl acetate in an inert atmosphere at temperatures of 0 ° C to 100 ° C, preferably at 20 ° C to 70 ° C, characterized in that the polymerization is carried out in the presence of an oxidation reduction initiator system. wherein the oxidizing component is tert-butylhydro202936 peroxide at a concentration of 1.10 ² to 32.10 ^-2 mol. ^11, based on the monomer and the reducing component, is a substituted thiourea of the formula II in II « R-C-NH-C-R wherein R is - Ph - C & HE-OCH 3, -CsHi-OC2H5, -CeHá-halo, EHD-NH 2, -CeHé- COOH, - (CH) _n CH 3, wherein n = 0 to 17 R 1 is —NHz, —NHCH3, —N, (CH5) 2 —NHC2H5, —N (C2H5) 2, -NHC3H7, —NHCeH11, —NHCsHs, - NHCeHu-Halogen ·, CH2CH2 Z \ —N O \ Z CH 2 CH 2 at a concentration of 0.5.10 ^-2 and 3. 10 “ ² mol. 1 to ¹ based on the monomer, wherein the molar ratio of oxidizing component to reducing component is 1 to 1 to 16 to 1, preferably 2 to 1 to 6 to 1.