CZ278507B6 - Process for preparing vinyl chloride homopolymers and/or copolymers - Google Patents

Abstract

Method of production is realized by suspensing homopolymerization or copolymerization of vinylchloride, in which a protecting colloid in mass 0,02 to 0,3 per cent of weight related on monomers is created from 9 to 90 per cent of weight with minimum one partial ketal and/or with acetal of polyvinylalcohol or of partial saponifyied polyvinylacetate with polymerizating degree 650 to 1800. In cause of acetalisated or ketalizated partial saponifyied polyvinylacetate is degree of hydrolysis 68 to 94 per cent mol. Their degree of acetalisation or ketalisation is 0,5 to 30 per cent surplus of protecting koloids to 100 per cent weight is created with minimum one cellulose ether.

Description

The invention relates to a process for the production of homopolymers and copolymers of vinyl chloride (VC) by suspension homopolymerization or copolymerization of VC in the presence of suitable combined protective colloids, depending on the quality requirements, in particular bulk density, morphology and grain size distribution of the polyvinyl chloride suspension. copolymer.

In the suspension copolymerization of vinyl chloride polymerizations and as the protective colloids or dispersants used mainly derivatives of cellulose, especially cellulose ethers alkylhydroxypropylétery cellulose, especially methylhydroxypropylcellulose, but also of polyvinyl alcohol and partially saponified polyvinyl acetate / Hayashi, S. et al .: Kobunshi Kagaku 20, 1963, with _C 303-311; CA 61 5802 (1964); Zilberman EN (ed.): Polivenie i svosti polivinilchlorida, pp. 66-77. Izdatelstvo Khimija Moscow (1968) /. However, these protective colloids are no longer sufficient to produce polyvinyl chloride and vinyl chloride copolymers of targeted properties, in particular grain morphology and distribution, which are associated with flowability, bulk density, and other product quality parameters. Therefore, other types of protective colloid dispersants are sought. Thus, a mixture of partially saponified polyvinyl acetate, sorbitol fatty acid ester and hydroxypropylcellulose is used. Then the product prepared by saponification of vinyl acetate copolymer with 0.5-5 mol%. acrylic acid, crotonic acid, optionally by hydroxyethylation of polyvinyl alcohol or by etherification of epichlorohydrin / jap. U.S. Pat. 5—5029879 (1.3.1980); 5-7014608 (Jan. 25, 1982) and 5-3144989 (Dec. 16, 1978) /. Furthermore, a combination of polyvinyl alcohol having a degree of hydrolysis of 30 to 50 mol% is used for suspension polymerization (European Pat. 2612). with hydroxypropylcellulose and the like, the copolymerization of VC with propylene (European Pat. 96 363) and other comonomers (German Pat. No. 2,610,021) is also carried out. However, there are problems with the reproducibility of the produced suspension polymers and VC copolymers. In this respect, technical progress is represented by the methods according to MS. 267 333 and 267 378, in which thermally and thermally-oxidatively modified types of polyvinyl alcohol and partially saponified polyvinyl acetate are used as dispersants. Separately, however, they do not allow greater flexibility in the morphological and other properties of the suspension of vinyl chloride homopolymers and copolymers, similar to polyvinyl alcohol-modified acetalization or ketalization alone (cf. author's certificate 266 976). Similarly, the dispersion system based on modified cellulose ether and polyvinyl alcohol, respectively, has a similar limited use. partially saponified polyvinyl acetate / GDR pat. 143 080; Kurraray Co. Ltd.: Jap. U.S. Pat. 62,530 (1974)].

SUMMARY OF THE INVENTION

However, according to the present invention, a process for the production of homopolymers and / or copolymers of vinyl chloride by suspension homopolymerization and / or copolymerization of vinyl chloride under the initiating effect, radical initiators and other excipients, protective colloids mainly based on partially acetalized and / or ketalized polyvinyl alcohol and its derivatives, 02 to 0.3% by weight, based on the monomer or monomers to be used, such that the protective colloid constitutes, from 9 to 90%, at least one polyvinyl alcohol ketal and / or acetal and / or partially saponified polyvinyl acetate, having a polymerization degree of 650 to 1800

And, in the case of acetalized and / or ketalized partially saponified polyvinyl acetate having a degree of hydrolysis of 68 to 94 mol. % with a degree of acetalization and / or ketalization of 0.5 to 30%. The remainder of the protective colloids to 100% is at least one cellulose ether.

An advantage of the method according to the invention is the possibility to utilize a more technically available assortment of protective colloid mixtures. The possibility of achieving a high porosity of the powder, depending on the morphology, bulk density, grain distribution distribution of the homopolymer or copolymer suspension, without seriously interfering with technology and process control, by simply changing the composition of the protective colloid or protective colloids to produce a reproducible suspension of desired technical parameters.

The method allows considerable flexibility in the production of different PVC suspension types and VC copolymers.

Suitable vinyl chloride comonomers are vinyl acetate, vinylidene chloride, alkyl acrylates, methyl methacrylate and alkyl methacrylates, trichlorethylene, maleic anhydride and alkyl esters of maleic acid, itaconic acid and alkenes.

The excipients are secondary dispersants or secondary suspension stabilizers, such as partially saponified fats, partially esterified polyols, partially or fully esterified sorbitol with saturated and unsaturated fatty acids, polyethoxylated sorbitol esters, polyethylene glycol esters, urea-formaldehyde condensates, polyether-trichloro-ester condensers, polyetheroxyalcohol condensates, ethylene oxide with propylene oxide and the like.

Other excipients may be molecular weight regulators such as trichlorethylene, chloroform, carbon tetrachloride, 2-mercaptoethanol, less suitable, but aliphatic aldehydes are useful. Then antifoams, reducing agents and antioxidants such as phenols, alkylphenols, in particular 2,6-di-tert. butyl-4-methylphenol, organic phosphites, sulfur dioxide, hydrosulfites, nitrites, formaldehyde sulfoxylates, ascorbic acid and polyethylene polyamines. They are also higher aliphatic unsaturated and saturated alcohols, but also cyclohexanol and alkylcyclohexanols, mixtures of monovalent and divalent alcohols. The excipients also include pH regulators of the polymerization or copolymerization environment, such as alkali metal hydrophosphates, organic acid salts and the like.

Protective colloids for carrying out the process according to the invention consist mainly of partially acetalized and / or partially ketalized polyvinyl alcohol, but most often partially ketalized or partially acetalized types of partially saponified polyvinyl acetate, the starting partially saponified or hydrolyzed polyvinyl acetate having a degree of hydrolysis of polyvinyl acetate of 68 to 100. % has a polymerization degree of 650 to 1800. such types are either ketalized with an aliphatic ketone C 8 to C 8, most preferably methyl ethyl ketone, methyl isobutyl ketone or cycloaliphatic ketones C 8 to C ₁₀ , most preferably cyclohexanone or methylcyclohexanone.

2GB 278507 B6

In the case of acetalization of polyvinyl alcohol or of different types (a defined range), partially saponified polyvinyl acetate suitable are aldehydes Ci to 'C _12, most preferably, however, aldehydes, C ^ _ to _Cg. Acetals of aldehydes higher than C ₁₂ are less soluble in the environment of a suspension polymerization or copolymerization like and, if wanted be used: the type partially saponified or zhydrolyzovaného polyvinyl acetate having a degree of hydrolysis below 68 mol. %. A similar situation would also apply in the case of acetalization or ketalization of polyvinyl alcohol or partially saponified polyvinyl acetate to a degree of ketalization or acetalization above 30%.

Protective colloids based on cellulose derivatives include, in particular, cellulose ethers such as methylhydroxypropylcellulose, methylcellulose and other alkylcelluloses, hydroxyethylcellulose, hydroxypropylmethylcellulose, carboxymethylcellulose, and the like.

The method of production is mainly discontinuous, but can exceptionally be carried out: semi-continuously or continuously.

Further data on carrying out the production method according to the invention as well as other advantages are evident from the examples.

Example

An autoclave of a volume of 50 dm ^3, and opatrencm duplikátorom propeller stirrer (300 in FIG. Min ^"1) was charged in 23 kg demineralized water in order to hold, 25 g of a partially saponified fat (emulsifier C), 30 g of a mixed initiator (EEA-80) consisting of 50% by weight, a mixture of peroxides (70% rel. bis-2-ethylhexylperoxydicarbonate, 28% rel. benzoylperoxy-2-ethylhexyl carbonate and 2% rel. dibenzoyl peroxide) in xylene, 17 g protective colloid (i.e. 0.1. % (w / v vinyl chloride) and 17 kg vinyl chloride (VC). The autoclave is heated to a temperature of 55 t 0.5 ° C, and homopolymerization at this temperature is carried out for 5.5 hours. Then the contents of the autoclave are cooled, the unreacted vinyl chloride is released and the suspension is drained, centrifuged with demineralized water and then dried, the vinyl chloride (PVC) is weighed, calculated

K value, bulk density, absorption of wetting agent and sieve analysis.

and washing the suspension polyconversion obtained on the centrifuge, determining its

Methyl hydroxypropylcellulose (Methocel F 50) and partially saponified polyvinyl acetate (Sloviol-R) in the form of an aqueous solution (sol) at a concentration of 16.5% by weight, with a saponification degree of 86.0 mol, are investigated as protective colloids. %, a polymerization stage of 1,140 and a dynamic viscosity of a 4 wt.% aqueous solution, at a temperature of 20 DEG C. = 11.56 mPa.s. and a surface tension of the 4 wt. = 45.5 mNm ^-1 . Furthermore, this partially saponified PVAL acetalized with formaldehyde (PVAF) for an acetalization degree of 5.6% rel., On the other hand with cyclohexanone (PVAZ) for a ketalization degree of 8.1% and n-butyraldehyde acetalized to 18.47% (PVAB).

-3GB 278507 B6

Then a partially saponified polyvinyl acetate (Alcotex 72.5) having a degree of saponification (hydrolysis) of 71 mol. %; a polymerization step of 700; by surface tension of an aqueous solution (sol) of 4 wt. ~ 42.0 mN.m ^-1 and the dynamic viscosity of this aqueous solution at 20 ° C = 6.7 mPa · s.

Additional reaction conditions and experimental results are shown in Table 1.

Table 1

Protective colloid VC Conversion (*) Bulk weight (kg.m ^) Moisture absorption (min) Sieve analysis of PVC powder (in $) species quantity (1 w / vC) mesh size trap (mm) 1.0 0.250 0.200 0.160 0.100 0,063 overflow Methocel F-50 Alcotex 72.5 Sloviol-R PVAE PVAB PVAZ 0.1 0.1 0.1 0.1 0.1 0.1 82 82 82 82 82 569 472 block 670 586 636 > 30 9 not rated > 30 > 30 > 30 0.1 0,1> a) 0.3 0.1 0.1 2.8 8.5 20.8 3.3 7.2 10.0 33.6 19.8 7.6 20.8 13.6 36.7 23.0 12.5 23.2 37.2 12.5 23.0 54.5 36.4 24.0 8.5 5.5 15.1 12.0 12.4 1.6 7.9 7.0 1,2 PVAF Methocel F-50 0.04 0,06 ' 82 82 492 10 0.1 5.6 1.6 32.4 35.2 8.0 7.2 PVAZ. Methocel F-50 0.04 0.06 82 527 19 Dec 0.1 5.2 6.4 24.8 23.6 12.0 28.0 PVAZ Methocel F-50 0.03 0.07 82 526 > 30 0.5 2,0 2.4 3.2 42.0 34.0 16.4 PVAZ Methocel F-50 0.07 0.03 82 540 19 Dec 0.1 0.4 1,2 28.4 58.4 8.0 3.2 PVAZ Methocel F-50 0.01 0.09 82 499 10 0.1 1,2 3.2 18.0 43,2- 15.2 19.2 PVAZ Alcotex 72.5 Methocel F-50 0.02 0.06 0.02 82 498 11 0.4 2.8 5.2 16.0 63.2 8.8 4.0 FVAF Alcotex 72.5 Methocel F-50 0.02 0.06 0.02 82 607 > 30 0.2 5.2 7.6 16.0 60.8 4.8 5.6 PVAB Methocel-50 0.04 0.06 82 498 12 0.2 2.8 5.2 16.0 63.2 8.8 4.0

-4GB 278507 B6

Example 2.

The procedure is similar to that of Example 1, except that instead of homopolymerization of VC, suspension copolymerization of VC is carried out with vinyl acetate and without partially saponified fat. The autoclave feed consisted of 30 kg of demineralized water, 9 kg of vinyl chloride, 2 kg of vinyl acetate, 30 g of initiator xylene solution and 20 g of protective colloid, which in the first experiment was methylhydroxypropylcellulose alone and 12 g of methylhydroxypropylcellulose and 8 g of partially acetilized polyvinyl alcohol. The copolymerization temperature is 66 + 0.5 ° C and the copolymerization is brought to a pressure drop of 0.4 MPa. This results in a monomer conversion of 84 ± 2% to the copolymer.

The copolymer obtained from the first experiment has a bulk density; 705 kg.m ^-3 and in the second experiment 720 kg.rn ' ³ , flowability 26.5 s, resp. 19.0 s; viscosity in both cases = 50 cm ³ / g; by sieve analysis, the 0.250 mm mesh retention is 1.5%, resp. 1.45%; for sieves 0.20 mm is 0.5, respectively. 7.5; for mesh 0,160 mm 0,9 resp.

16.2%; on site 0.100 is 9.7, respectively. 53.5%; for mesh 0.063 mm is 50.7, respectively. 14.5% and overflow 36.7%, respectively. 6.9%.

Example 3

The procedure is similar to that of Example 1 except that a mixture of 3.4 g (i.e. 0.02% w / v) of PVAZ and 30.6 g (i.e. 0.18% w / v) Methocel F-50. The VC conversion is 82%. The bulk density of the PVC slurry is 532 kg / m ³ ; absorption of plasticizer by PVC powder is 21 min .; powder retention on a 1.0 mm mesh screen is 0.1%, on a 0.063 mm mesh screen 13.1. % and the overflow through a 0.063 mm screen is 4.8.

Claims (4)

P A T E N T E C O R T E R T C A T Method for producing homopolymers and / or copolymers of vinyl chloride by suspension homopolymerization and / or copolymerization of vinyl chloride under the initiating effect of radical initiators and other auxiliaries, protective colloids mainly based on partially acetalized and / or ketalized polyvinyl alcohol and its derivatives, at a concentration of 0.2 to 0 3% by weight, based on the monomer or monomers employed, characterized in that the protective colloid constitutes 9 to 90% of at least one polyvinyl alcohol ketal and / or acetal and / or partially saponified polyvinyl acetate, with a polymerization degree of 650 to 1800, and in the case of acetalized and / or ketalized partially saponified polyvinyl acetate having a degree of hydrolysis of 68 to 94 mol. %, with a degree of acetalization and / or ketalization of 0.5 to 30%, the remainder of the protective colloids up to 100% being at least one cellulose ether. 2. The method of claim 1, wherein the ketal with polyvinyl acetate and / or partially saponified polyvinyl acetate forms a ketal formed with an aliphatic and / or cycloaliphatic ketone, preferably cyclohexanone. 3. The process according to claim 1, wherein the acetal, preferably the polyvinyl alcohol form and / or the partially saponified polyvinyl acetate, is formed by acetalizing with at least one aliphatic aldehyde C1- _C12 , preferably formaldehyde. 4. A method according to claim 1, wherein the cellulose ethers comprise methylhydroxypropylcellulose, ethylhydroxypropylcellulose, methylcellulose, propylcellulose, hydroxyacetylcellulose, carboxymethylcellulose.