DD145539A2 - PROCESS FOR PREPARING POLYMERS OF VINYL CHLORIDE - Google Patents

Abstract

The invention relates to a process for the preparation of polymers of vinyl chloride, which are suitable for both hard and for soft processing, by suspension polymerization. The aim is to increase the plasticizer capacity of the PVC without impairing other properties important for processing, such as bulk density and flowability. By using certain dispersants or dispersant combinations and adding suitable substances to the polymerizing system, this object is to be achieved. The method consists in that instead of the vzeiteren cellulose ether described in WP 138 776 in admixture with a MethyIehydöxypropylcellulose a partially saponified Polyvinylazetat is used.

Description

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Process for the preparation of polymers of vinyl chloride

Field of application of the invention ';

The invention relates to a process for the preparation of polymers of vinyl chloride, which are suitable for both hard and soft processing, by suspension polymerization, wherein as suspension stabilizer a hydroxypropyl cellulose, the 19-24 wt.% Methoxy- and 4 - .1.2 wt.% Hy & roxypropoxygruppen (degree of substitution 1.2 --1,7) and the viscosity of a 2 followed by aqueous solution of more than 100 mPa.s at 20 ⁰ C, or a mixture of the above methylhydroxypropylcellulose having a y / Eiteren cellulose ether with a degree of substitution of 1.6 - 2.5 and a viscosity of a 2% aqueous solution at 20 ⁰ C of more than 10 mPa 's in the ratio 25: 1 to 3 in a total concentration of 0.005 to 0.15 wt,%, preferably of 0.01 to 0.1% by weight (based on the aqueous phase of the polymerization mixture) in combination with an unsaturated sorbitan ester in a concentration of 0.001 to 0.3% by weight, preferably from 0.01 to 0.15 g % by weight (based on the monomer phase) and / or with 0.005 to 1.5 % by weight (based on monomer phase) of a phenylglycerol ester and / or with 0.01 to 0.5% by weight (based on monomer phase) of an alcohol with 8 Carbon atoms, optionally with the addition of inorganic salts, in such a way that the interfacial tension between aqueous and organic phase (measured with trichlorethylene as comparative

Substance) is not less than 9.8 · 10 H / cm, according to the patent application WP 43 $

C characteristic of the known technical solutions

The preparation of homo-, co- and graft polymers of vinyl chloride by suspension polymerization is known. The polymerization is controlled so that polymers are obtained with certain properties corresponding to the intended use. For the polyvinyl chloride processors, the bulk density and plasticizer capacity of the polymer are of particular importance. However, both properties are related in such a way that, as a rule, the improvement of one size leads to a deterioration of the other.

Thus, methods for improving plasticizer receptivity are known that are based on the addition of certain substances to the polymerizing system. Thus, it is known to use aliphatic or aromatic hydrocarbons or alcohols for the abovementioned purpose (US Pat. No. 2,875,186, 3,488,328). The disadvantage of these methods is that relatively large amounts of additives have to be used to achieve improved plasticizer capacity. This has the consequence that the polymerization rate is reduced, the molecular weight of the resulting PVC is lowered and the thermal stability deteriorates. Furthermore, problems arise in cleaning the PVC and in recovering such relatively low volatiles from the PVC powder.

It is also known to increase the plasticizer capacity of the PVC by adding long-chain fatty acids or their esters or by adding ionogenic or non-ionic surface-active substances, often combined with further additives such as reducing agents, sum of polymerization mixture (DB-OS 2 365 134, 2 151 703, DE - PS 1 545 179, DE - OS 2 244 905, 2 143 604).

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Also described is the combination of suspension stabilizers for influencing the plasticizer receptivity (US Pat. No. 3,879,365, DE - AS 1 720 328, DE - OS 2 209 592). Furthermore, the addition of esters of sucrose or of sorbitol with long-chain fatty acids is known as a softening agent improving component (DE-OS 2 310 431, 2 509 998).

Although the said processes lead to a more or less strong improvement of the plasticizer absorption of the corresponding PVC, this improvement is associated with a deterioration of other important PVC properties, in particular with lowering the bulk density and the flowability.

Object of the invention

The aim of the invention is the preparation of homo-, co- and graft polymers of vinyl chloride, which in addition to a high bulk density have a high Weichraacheraufnahmefähigkeit.

Explanation of the invention of the invention

- The technical problem which is solved by the invention. The invention has for its object to develop a suspension polymerization, which makes it possible to produce by combining suspension stabilizers and by adding suitable substances polymers of vinyl chloride, which have a high bulk density and a very good plasticizer receptivity.

Features of the invention

The object was inventively achieved in that instead of the other cellulose ether having a degree of substitution of 1.6 - 2.5 and a viscosity of a 2% aqueous solution at 20 ⁰ C of more than 10 mPa · s a partially saponified polyvinyl

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Acetate is used with a Restazetatgehalt of 65-95 mol% and a molecular weight of 50,000 - 125,000 g / mol.

The suspension polymerization is carried out in a known manner in the temperature range from 30 ^° C. to 85 ^° C. with oil-soluble initiators which have a half-life of from 0.2 to 70 hours at 55 ^° C.

The process of the present invention is applicable to vinyl chloride polymerizations as well as grafting and copolymerizing vinyl chloride with one or more copolymerizable monomers,

The added unsaturated sorbitan esters are mono-, di- and triesters of rapeseed oil fatty acid and sorbitan hydride and mixtures of this ester.

The fatty acid glycerol esters used are mono-, di- and triglycerides of stearic or oleic acid or mixtures of such esters and / or esterification products of rapeseed oil fatty acid with sorbitan hydride and glycerol.

The inorganic salts used are preferably sodium bicarbonate, sodium hydrogen phosphate, sodium dihydrogen phosphate and sodium phosphate in a concentration of 0.005-0.25% by weight (based on the aqueous phase).

The interfacial tension is measured by the drop volume method at 25 ⁰ C.

embodiments

The invention will be explained in more detail with reference to the following examples ^:

example 1

In a pressure autoclave made of stainless steel, equipped with stirrer, baffles and temperature and pressure measuring devices, 100 parts by weight (GT) of deionized water, 0.02 part by weight of methyl hydroxypropyl cellulose (19-24 wt.% Methoxy, 4-12 wt. (% hydroxypropoxy groups, viscosity of a 2% aqueous solution at 20 ⁰ C 105 mPa · s), 0.02 GT partially saponified polyvinyl acetate Restazetatgehalt 72.5%, molecular weight 58 000 g / mol), 0.22 pbw of a Fettsäureglycerinesters (molecular weight 355 g / mol, saponification number 16O mg KOH / g, iodine value 33), 0.037 part by weight of sodium bicarbonate and 60 parts by weight of vinyl chloride. The interfacial tension between aqueous and organic phase (measured with trichlorethylene as reference substance) is 10.8 · 10 N / cm «

The polymerization is started after addition of 0.0075 part by weight of diisopropyl peroxydicarbonate and 0.015 part by weight of azodiisobutyronitrile and carried out at 64.degree. The PVC obtained has a plasticizer absorption of 22.8 % (dioctyl phthalate) at a bulk density of 56O g / l and a narrow particle size distribution. The processing products within the soft sector are characterized by an extremely small number of specks (fish eyes).

Example 2

The polymerization mixture is prepared in the same way as in Example 1, except that 0.025 part by weight of a partially hydrolyzed polyvinyl acetate having a residual acetate content of 93.8% and a molecular weight of 82,000 g / mol is used instead of the partially hydrolyzed polyvinyl acetate mentioned in Example 1. The interfacial tension between aqueous and organic phase (measured with trichlorethylene as the comparative substance) is 11.0 x 10 N / cm.

The polymerization is carried out at 64 ° C. This gives a PVC having a bulk density of 570 g / l and a Weichmacherauf amount of 22.1 % (dioctyl phthalate).

Example 3

In a pressure autoclave are added 100 GT of deionized water, 0.02 part each of methylhydroxypropylcellulose and partially saponified polyvinyl acetate according to Example 1, 0.055 part by weight of a sorbitan oil fatty acid ester (molecular weight 440 g / mol, saponification 135 mg KOH / g, iodine value 83), 0.037 part by weight of sodium bicarbonate and 60 GT vinyl chloride. The interfacial tension between aqueous and organic phase (measured with trichlorethylene as comparative substance) is 10.0 · 10 N / cm ·

The polymerization is initiated by addition of 0.03 and 0.02 Dicetylperoxidikarbonat GT GT dilauroyl peroxide and carried out at 64 ⁰ C. This gives a PVC having a bulk density of 550 g / l and a plasticizer absorption of 25.4% (dioctyl phthalate) and a low residual monomer content. The processing products are almost free of specks.

Example 4

In a pressure autoclave are added 100 parts of demineralized water, 0.015 part by weight of a methylhydroxypropylcellulose and 0.015 part by weight of polyvinyl acetate according to Example 1, 0.1 part by weight of a mixed ester of sorbitan anhydride / glycerol and rapeseed fatty acid (molecular weight 645 g / mol, saponification value 170 mg KOH / g, iodine number 105, a weight ratio of fatty acid: sorbitan: glycerin as 10: I: 1), 0.056 GT sodium hydrogen carbonate and 60 parts of vinyl chloride · The interfacial tension between the aqueous and organic phases (amounts measured with trichlorethylene as comparison substance) 11.0 x 10 ~ ⁵ N / cm.

The polymerization is started after addition of 0.02 part by weight of diisopropyl peroxydicarbonate and carried out at 52.degree. The PVC has a bulk density of 56O g / l and a plasticizer uptake of 23.8 % (dioctyl phthalate).

Claims (1)

Inventor's pruch A process for the preparation of polymers of vinyl chloride which are suitable for both hard and soft processing by suspension polymerization, wherein the suspension stabilizer used is a hydroxypropylcellulose containing 19-24% by weight of methoxy and 4-12% by weight of hydroxypropoxy groups (degree of substitution 1, 2-7.7) and whose "viscosity of a 2% aqueous solution is more than 100 mPa.s at 20 ° C, or a mixture of the above methylhydroxypropylcellulose with another cellulose ether having a degree of substitution of 1.6-2.5 and a viscosity of a 2% aqueous solution at 20 C of more than 10 mPa · s in a ratio of 25: 1 to 1: 3 in a total concentration of 0.005 bpw to 0.15 wt%, preferably from 0.01 to 0.1 % By weight (based on the aqueous phase of the polymerization mixture) in combination with an unsaturated sorbitan ester in a concentration of 0.001 to 0.3% by weight, preferably from 0.01 to 0.15 % by weight (based on the monomer phase). and / or with 0.005 to 1.5 Gew.?o (relative to the monomer phase) of a Fettsäureglycerinesters and / or with 0.01 to 0.5 wt.% (Based on the monomer phase) of an alcohol having 8-20 carbon atoms, optionally with the addition of inorganic salts, used in such a way that the interfacial tension between aqueous and organic phase (measured with trichlorethylene as reference substance) is not less than 9, S · 10 ^-3 U / cm, according to patent WP 42> 2 ^ PKp , characterized in that instead of the other cellulose ether with a degree of substitution from 1.6 to 2.5 and a viscosity of a 2% aqueous solution at 20 ⁰ C of more than 10 mPa · s, a partially saponified polyvinyl acetate with a Restazetatgehalt 65-95 Mol% and a molecular weight of 50,000 - 125,000 g / mole is used.