CS196344B2 - Process for homopolymerisation and copolymerisation of vinyl compounds especially vinylchloride in suspension - Google Patents

Description

The invention relates to a process for the homopolymerization and copolymerization of vinyl compounds, in particular vinyl chloride, in the suspension phase.

It is known that in suspension copolymerization of vinyl chloride, suspension suspensions of, for example, cellulose ethers, polyvinyl alcohol and also polymers of alkali salts of maleic acid with styrene or vinyl acetate in a molar ratio of 1: 1 are used, for example as described in Houben-Weyl: Methoden der organischen Chemie , Volume 14, p. 881.

In general, using these stabilizers, it is not possible to obtain powdered products having a porous structure under normal suspension polymerization conditions. The production of powdered products with a porous morphology is only possible under polymerization under special conditions, for example using some cellulose ethers and intensive mixing at 58 ° C, but the particle morphology of the powdered products obtained in this way cannot be regarded as optimal.

Furthermore, it is known that the porosity of powdered polymerization products can also be increased by adding salts of two or more polyvalent metals with alkyl sulfonates and / or sulfates to commonly used colloidal stabilizers, as disclosed, for example, in U.S. Patent No. 3,706,705; British Patent Specification No. 10-22812. Polyhydroxybenzenes partially esterified with fatty acids are also added, for example according to U.S. Pat. However, the use of these porosity-enhancing additives has the disadvantage that these additives impair the electrical properties and thermal stability of the powdered product and prevent it. further processing into final transparent products.

The object of the invention is therefore to produce powdered polymer products based on vinyl compounds, in particular vinyl chloride, with improved dry-blend properties which can be advantageously used in plasticizer processing or in processing technologies for plasticized or hard mixtures without plasticizer 1.

The problem has been solved and the above-mentioned drawbacks of the known processes have been overcome by the process of homopolymerization and copolymerization of vinyl compounds, in particular vinyl chloride, according to the invention in suspension, which consists in using them as stabilizing and / or pore-forming additives. 0.05 to 0.3% by weight, preferably 0.08 to 0.15% by weight,

6 34 4 calculated on the amount of monomer used, partially hydrolyzed polyvinyl acetate having a hydrolysis stage of - 30 to 92 mol%, the polyvinyl acetate hydrolyzed to 65 to 92 mol%. it is water soluble, has a viscosity of 5 to 65 mPa. and precipitates in the temperature range, while polyvinyl acetate hydrolyzed to 30 to 65 mol%. it is water insoluble and forms a gel with bifunctional aldehydes.

Preferably, the partially hydrolyzed polyvinyl acetate of the hydrolysis step of 65 to 92 θ / ο mol is used.

It has been found that pulverulent polymers having the desired properties can be prepared by using conventional slurry polymerization technology instead of the stabilizers and pore-forming agents used hitherto as stabilizers and / or pore-forming additives which bind the known dispersing agents, in particular prepared polyvinyl acetate with a special structure of molecules.

The particular structure of the molecule is understood to mean that the partially hydrolyzed polyvinyl acetate according to the invention has a structure of strongly block nature, that is, free hydroxyl groups and hydroxyl groups esterified with acetate groups are arranged in block form. This is due to the manufacturing process, i.e. the course of the hydrolysis in the gel phase. This structure clearly distinguishes the partially hydrolyzed polyvinyl acetates of the invention from the known and commercially used partially hydrolyzed polyvinyl acetates.

Due to this structure, the water-soluble, partially hydrolyzed polyvinyl acetate according to the invention exhibits the specific property of a haze hysteresis. The water-insoluble polyvinyl acetate according to the invention forms a gel with the bifunctional aldehydes.

As to the blotting nature of the partially hydrolyzed polyvinyl acetates of the invention, the water-soluble, partially hydrolysable polyvinyl acetates are usable as stabilizers and pore-forming agents, and - the second, water-insoluble, partially hydrolyzed polyvinyl acetates are only usable in combination with a dispersant . These second polyvinyl acetates are also useful in combination with the water-soluble, partially hydrolyzed polyvinyl acetates of the invention.

In the process according to the invention, it is used to stabilize the suspension and / or to form pores, optionally together with known protective colloids of partially hydrolyzed polyvinyl acetate, which in the monomer phase is at least partially colloidly soluble and from which the water-soluble part due to the temperature of the aqueous solution separates and shows turbidity hysteresis. In contrast, the water-insoluble partially hydrolyzed - vinyl acetate forms a gel - with bifunctional aldehydes.

Partially-hydrolysed polyvinyl acetate usable according to the invention with the stated parameters can be produced by subjecting the polyvinyl acetate to lye-catalyzed hydrolysis. The hydrolysis is carried out in a mixture of solvents composed of at least 50% by volume and at most 98% by volume of a non-polar organic solvent and a polar solvent which is needed to replenish - up to 100% - by volume in which it is dissolved. - not less than 5% and not more than 60% of mixed polyvinyl acetate and not less than 0,1% and not more than 10% of mixed alkaline and / or alkaline-earth hydroxides. Mixed percentages mean weight / volume in grams per 100 cm ³ . By the action of the catalyst, polyvinyl acetate is hydrolyzed in the gel phase at a temperature of 10 to 80 ° C.

The partially hydrolyzed polyvinyl acetates produced in this way, whose hydrolysis degree lies between 65 and 92 mol%, are soluble in water and separated from their aqueous solutions by the action of a temperature at 30 to 95 ° C, exhibiting haze hysteresis. That is, the separation is irreversible and the partially hydrolyzed β-olyvinyl acetate dissolves in the water upon cooling - only after a prolonged period of time. In the prior art, hysteresis has not been observed with partially hydrolyzed polyvinyl acetate.

The partially hydrolyzed polyvinyl acetates produced by the process, whose degree of hydrolysis is less than 65 mol%, are not water-soluble. When exposed to acid in a mixture of propanol and water - along with bifunctional aldehydes such as glutaraldehyde, they form a gel in a short time. The gel is usually formed - sooner than in one hour. In the prior art with similarly partially hydrolyzed polyvinyl acetate, for example an Italian product, -Polivic. S-202 from Sigma was not observed - gel formation of this kind. Only after two hours .. there is a gel, for other reasons.

The suspension - polymerization - is carried out by known methods.

The advantages of the process according to the invention can be summarized as follows. In comparison with the types of polyvinyl alcohols currently used, the partially hydrolyzed polyvinyl acetates used according to the invention show their effect even at substantially lower concentrations, and as a result the thermal stability of the vinyl polymer produced according to the invention increases. By using the partially hydrolyzed polyvinyl acetate according to the invention, vinyl polymers having an optimal particle structure, a high plasticizer uptake ability, a narrow particle distribution and a high bulk density can be produced without the use of porosity enhancers. Partially hydrolyzed polyvinyl acetates can also be used in conjunction with stabilizers of other types as well as pore-enhancing additives.

The invention is further illustrated by the following examples.

He did

The polymerization was carried out in an acid-resistant autoclave with a usable volume of 5 liters and equipped with an impeller stirrer. 2850 g of deionized water, 1.5 g of partially hydrolyzed polyvinyl acetate having a hydrolysis degree of 65.7%, a viscosity of 4% solution at a temperature were metered into the autoclave. 20 ° C 10 mPa. with a cloud point of a 1% aqueous solution at 63 ° C and 1.5 ml of a 30% solution of 1-isopropyl peroxydicarbonate in xylene.

Then, 1500 g of vinyl chloride was pressurized through a valve under vacuum with a nitrogen pad. Upon completion of the addition, the stirrer speed was set to 700 mm ¹ , heating water was connected through the autoclave belonging to the test apparatus and the polymerization temperature was maintained at 53 ± 0.2 ° C. It was polymerized until the pressure dropped by 0.196 MPa compared to the highest measured autoclave pressure.

P 14 to 1 and d 2

The procedure described in Example 1 was followed except that 1.5 g of partially hydrolyzed polyvinyl acetate was used in place of the dispersing agent, whose hydrolysis degree was 66.6% and whose viscosity measured in a 4% solution at 20 ° C was 12%. mPa. s and its 1% aqueous solution showed a cloud point at 42 ° C.

Example 3

The procedure was as in Example 1 except that 1.5 g of partially hydrolyzed polyvinyl acetate was used instead of the dispersant therein, which was hydrolyzed to 85.5% and whose 4% solution at 20 ° C had a viscosity of 12 mPa. . and a 1% aqueous solution showed a cloud point at 74 ° C.

Example 4

The procedure described in Example 1 was followed except that only one half of the dispersant therein was used and the other half (0.75 g) was replaced with hydroxymethylcellulose.

Example 5

Comparative example. The procedure was as described in Example 1 except that partially hydrolyzed polyvinyl acetate in an amount of 1.8 g was used instead of the dispersing agent therein, which did not precipitate out of its aqueous solution when the temperature was raised, had a hydrolysis stage

78.8% and its 4% aqueous solution had a viscosity of 33.4 mPa. s (Cohsenol KH-17, manufactured by Japanese company Ni.p-pon).

Example 6

Comparative example. The procedure described in Example 1 was followed except that 1.8 g of partially hydrolyzed polyvinyl acetate, which showed no turbidity point, was used instead of the dispersant therein, the hydrolysis stage had

79.2% and a 4% aqueous solution at 20 ° C showed a viscosity of 52 mPa. s (IL-250, manufactured by the Japanese company UNITIKA).

Example 7

Comparative example. The procedure described in Example 1 was followed except that 1.8 g of partially hydrolyzed polyvinyl acetate, which showed no turbidity point, had a hydrolysis degree of 88% and a 4% aqueous solution thereof at 20 ° C, was used instead of the dispersant therein. viscosity 21 mPa. s (GM-14, manufactured by Japanese company NIPPON).

Example 8

Comparative example. The procedure described in Example 1 was followed except that 1.8 g of partially hydrolyzed polyvinyl acetate, which showed no cloud point, had a hydrolysis degree instead of the dispersant used therein.

86.4% and 4% aqueous solution at 20 ° C had a viscosity of 49 mPa. s (UP-240, manufacturer Japanese company UNITIKA).

Example 9

The procedure described in Example 5 was followed except that only 1.5 hydrolyzed polyvinyl acetate was used instead of 1.8 g and at the same time polyvinyl acetate hydrolyzed to 53.3 mol% was added to the autoclave as pore-forming component according to the invention. in an amount of 1.5 g.

Example 10

The procedure described in Example 9 was followed and the pore-forming additive used was 46.8 mol% according to the invention. hydrolyzed polyvinyl acetate.

Example 1 ^{0 0}

The procedure was similar to that described in Example 6 except that only 1.5 g was used instead of 1.8 g of partially hydrolyzed polyvinyl acetate, and the partially hydrolyzed polyvinyl acetate was added as a pore former in Example 9 in an amount such as there.

Example 12

The procedure of Example 9 was followed, except that the partially hydrolyzed polyvinyl acetate used therein, having a hydrolyzing band, was used instead.

78.8 mol%, hydroxymethylcellulose was used.

Example 13

The procedure described in Example 1 was followed except that hydroxymethylcellulose was used instead of partially hydrolyzed polyvinyl acetate.

ilňOlňCOOO I ιη Ю I, _п

I ГЧ <4 Гч г Г »Г> Гч | ITJ ¹ о no ω s cos I г-1 I -г

О CD (Э 1П (D О О CD) of ι <in in r r r r r of of of of of of Γ Γ Γ Γ Γ Γ Γ Γ Γ о о ιη оо 'Ф со юсО ^ смсмсососо ^' фсою о ιη ~ ιη ιη ιη ~ (ι ιη ιη cD ~ in ~ ιη CD ιη co 04 * of r * T xjT t <of tA oo 00 * rH 04 CO 04 H 04 CO 04 04 04 rH

CD CD CD i IDIO | ^ O ^ in CD СЭ1П of of-I 03 * CO I o oo * oo * co of

O ^ CD СО _л СО _л CM CD OD r ^ rH OJ t> f rf rH 00 in co * tx * 00 * of rH 00 * СМСОСОСМгНгНгНтНСМСМСМСОСМ

OOOOCDCOinOJOCDOOOinOO in0JC0in00t> 0) 00rHQ> 00OCD ^ Xf ^^ COCOCOCO ^ COOOinx »

199344

The table shows that using polyvinyl acetate hydrolyzed to 65-92 mol% without additives yields polyvinyl chloride powder of higher bulk density and higher plasticizer absorption than using partially hydrolyzed polyvinyl acetate known in the art. It will further be appreciated that polyvinyl acetates hydrolyzed to 30-65 mol% when added as pore-forming additives increase the bulk density and absorption of the polyvinyl chloride powders. Lower values were measured using a single stabilizer.

Claims (2)

SUBJECT OF THE INVENTION Process for the homopolymerization and copolymerization of vinyl compounds, in particular vinyl chloride, in suspension, characterized in that 0.05 to 0.3% by weight, preferably with further dispersing additives, is used as stabilizing and / or pore-forming additives in the polymerization, preferably 0.08 to 0.15% by weight, based on the amount of monomer used, of partially hydrolyzed polyvinyl acetate having a hydrolysis stage of 30 to 92 mol%, the polyvinyl acetate being hydrolyzed to 65 to 92 mol%. it is water soluble, has a viscosity of 5 to 65 mPa. s and in the temperature range of 30-90 ° C precipitates while polyvinyl acetate hydrolyzed to 30-65 mol%. it is water insoluble and forms a gel with bifunctional aldehydes. 2. Process according to claim 1, characterized in that partially hydrolyzed polyvinyl acetate having a hydrolysis degree of 65 to 92 mol% is used.