CS211935B1 - Method of suspension polymeration of the vinylchloride - Google Patents

Abstract

In PVC prepn. by vinyl chloride suspension polymerisation under pressure in an agitator-reactor, the monomer is dispersed in the aq. phase with the addn. of polymerisation initiators, macromolecular emulsifiers, tensides and further addtives. At least 2 wt.% of the tensides in polymerisation mixt. consist of insoluble salts, (I), of 8-20 C carboxylic acids, contg. at least one unsaturated bond, with di- or polyvalent metal cations. W.r.t. vinyl chloride, the concn. of (I) is pref. 0.002-0.2 wt. %. The polymer particles have good morphology and high porosity, achieved with less than half of previously used tenside concns. Bulk wt. does not decrease appreciably with increasing porosity.

Description

The present invention relates to a process for the production of polyvinyl chloride by slurry polymerization.

In vinyl chloride suspension polymerization under pressure in stirred reactors, the monomer is dispersed in the aqueous phase with the addition of suitable polymerization initiators, emulsifiers, surfactants and other additives.

In addition to the important qualitative features of the resulting polymer for three particle size distributions, the bulk density and in particular the particle morphology characterized by porosity, specific surface area and uniform internal structure. A sufficiently high porosity of the particles allows for rapid interaction with and other ingredients and good processability. In the processing without zinc, the interaction of the porous polymers with the processing additives is facilitated and the plasticization proceeds evenly. The particle porosity also has a significant effect on the demonomo. The polymer morphology is determined primarily by the composition of the system, the mixing and polymerization regimes.

As stabilizers, moleic emulsifiers of lyophilic nature are used, for example, cellulose ethers such as oxycellulose, mosyl] hydroxypropylmethylcellulose, hydroxypropylcellulose, polyvinyl alcohol, polyvinyl alcohol containing 10% by weight of acetic acid, polyvinyl acetate, 10% by weight of acetate, vinyl acetate and the like. Salts of some of the aforementioned emulators are often used to improve performance.

When using mC: colecular emulators alone, the desired porosity and optimum particle morphology are generally not achieved.

It is known that in a given emulsifier system the porosity of the polymer stop at a lower conversion, the sudden release of unreacted monomer from the suspension, the optimization of the mixing mode and the polymerization conditions can be increased somewhat. However, these interventions do not have sufficient effect.

Therefore, other monomer-soluble or dispersible auxiliaries, referred to as secondary emulators, are used to achieve optimal porosity. These include, for example, nonionic surfactants such as mono- to tri-esters of higher methacids with sorbitol or tabita, mono- to diglyoefides of higher fatty acids, condensates of propylene oxide with ethylene oxide, low-ethoxylated higher fatty alcohols or acids and the like. Non-alcoholic polyvinyl alcohol with an acetate content of more than 30%, insoluble in water, is also used. Preferably, water-insoluble types are used from said secondary emulators, since the use of water-soluble types generally results in a polymer having a lower bulk density.

The required porosity depends on the K-value of the polymer and its processing. In the polymerization of plasticizers with plasticizers, the advantage is the advantage. In the preparation of the polymer

With a K-value of 70, a secondary batch of at least 1 g per kg of vinyl chloride _{to the} polymerization mixture is required to achieve a porosity of about 0.29 ml / g. In order to achieve higher porosity, it is necessary to increase the concentration of the secondary emate to up to 1.5 to 2 g per kg.

211-935 ridu. Although surfactants of this type are known, for example sorbitan oleate, oleic acid glycerides, i.e. derived from unsaturated matic acids, which are somewhat more effective, they have the disadvantage of having a retarding effect on polymeeaac. It is therefore necessary to increase the initiator concentration by up to 20% or more to achieve the same conversion and polymerization cycle.

It has now been found that polymers with high porosity can be prepared by using water-insoluble salts of higher matte acids enveloping at least one unsaturated bond.

SUMMARY OF THE INVENTION The present invention provides a process for the slurry polymerization of vityl chloride under printing in a stirred reactor, wherein the monomer is dispersed in the aqueous phase at a rate of about 100%. The addition of polymerization initiators, the polyolefins containing lyophilizers of lyophilic nature, surfactants and other additives, wherein at least 2% of surfactants in the polyoerization mixture are salts of carbon acids with 8 to 30 carbon atoms. atoms and at least one unsaturated bond with cations of two and all-powerful metals.

In the process according to the invention, the insoluble anionic surfactants are considerably more effective than the surfactants used hitherto, so that the same effect is obtained with a concentration of more than half. The polymer obtained is cleaner. Insoluble anionic surfactants derived from acids with one double bond practically teretardine polyoeerai. Conventionally used secondary emitters are prepared as a rule by demanding theories. Insoluble knock-off surfactants can be used as a substance or prepared in situ in a polymer-autoclave without healing or otherwise adversely affecting the polymer. ^{This has a} favorable effect on the processing of ^ ls ^ properties. '

A suitable acid component of the insoluble clone surfactants is a branched or unbranched mono- or dicarboxylic acid having a number of carbon atoms greater than eight containing one or more double bonds or triple bonds, for example oleic, linoleic, linolenic, stearolic and the like. They may contain other functional groups in the chain, for example hydroxyl, epoxy and the like. These acids cannot be used. in pure form, the same or intentionally prepared mixtures or mixtures obtained by the cleavage of fats and oils such as rapeseed, soybean, sunflower oil and the like can be used. Caboic acid can be metered into the aqueous phase or dissolved in vityl chloride or other solvents or as water-soluble salts.

In order to optimize the effect, it is expedient to know the composition used. kreslin. If saturated acids are present in the salt, the effect decreases with their content.

Suitable cations for the preparation of insoluble cross-linking surfactants are two or more monovalent metals such as magnesium, calcium, barium, tin, lead and the like. In the preparation of in situ, they can be used as oxides, hydroxides or water-soluble salts. If the starting materials or hydroxides are used, it is preferable to use them in an amount greater than that specified. To achieve full effect during polymerization and suppress unsaturated bond retardation

It should be ensured that the pH throughout the polymerization is greater than 7. This is achieved by using appropriate pH regulators or hydroxides dosed at the beginning or during the polymerization. Insoluble anionic surfactants may be prepared at the beginning or during polymerization. If desired, it is possible to suppress the effect on increasing porosity and to induce acid retardation by adjusting the pH during polymerization to the acidic region.

F

The use of insoluble anionic surfactants is not limited by the polymerization temperature, polymerization and mixing modes, and conventional polymerization initiators such as organic peroxides with suitable disintegration rates may be used. 10% gelatin, saponified copolymers of vinyl acetate with olefins and the like, or mixtures of macromolecular emulsifiers of lyophilic nature · Insoluble anionic surfactants can be combined with other types of secondary emulsifiers of nonionic nature and soluble or dispersible in vinyl chloride with sorbitans, glycerides, polyvinyl alcohol and · Because water-insoluble anionic surfactants are very effective, a very small proportion is sufficient when mixed with other types of secondary emulsifiers to have an effect · Their effectiveness is not affected if the polymerization is carried out in the presence of small amounts of oxygen, water-soluble peroxides such as dartboard, butyl hydroperoxide, persulphates, hydrogen peroxide or the like, or a defoamer dosed at the beginning or during the polymerization, or with carriers, precipitants, antioxidants, inert gases or other substances.

The examples given show the advantages of using water-insoluble anionic surfactants in vinyl chloride suspension polymer.

Polymerizations were carried out under the same conditions, the type, concentration and method of preparation of insoluble anionic surfactants were changed. · For comparison, results are shown using some nonionic surfactants soluble in vinyl chloride.

The polymerizations were carried out in an 8 liter stainless steel laboratory autoclave equipped with a continuously variable impeller type impeller stirrer, baffles, automatic temperature control duplicator. 4,200 ml of water phase and 2,400 g of vinyl chloride were metered into the autoclave · A mixture of methylhydroxypropylcellulose and methylhydroxypropylcellulose at 1.4 g per kg vinyl chloride, dicetyl peroxide dicarbonate was used as initiator at 2.2 mM per kg vinyl chloride, the pH of the aqueous phase was adjusted to 10-11. After the aqueous phase was metered in and before the vinyl chloride was dosed, the steam space was flushed with nitrogen and reactor evacuated to 20 to 30 kPa · Stirrer speed was 330 rpm, poles—

211 93S measuring temperature 54 - 0.5 ° C. After 220 minutes and 230 minutes of polymerization, a pressure drop occurred

300 minutes, the polymerization was stopped by undermining and discharging the monomer-reacted monomer. The conversion was 86 to 88% · Polyvinyl chloride was analyzed after washing and drying according to ČSN 64 3200. The viscosity number of the polymer was 124 - 4 ml / g, which corresponds to a K-value of 70 - 1. and the time of absorption of the plasticizer.

Example 1

Sorbitan monostearate was used at a concentration of 1.3 g / kg VC, the pH of the aqueous phase was adjusted to 10. The resulting polyvinyl chloride had a mean particle size of 108 µm, a bulk density of 482 g / l, a porosity of 0.32 ml / g and a plasticizer absorption time of 8 minutes. Practically the same results were obtained using sorbitan monopalmitate or sorbitan monolaurate.

Example 2

Calcium oleate was used at a concentration of 0.25 g / kg vinyl chloride, the pH of the aqueous phase was adjusted to 11. The average polymer particle size was 104 µm, bulk density 487 g / l, porosity 0.30 ml / g and plasticizer absorption time 10 minutes. The pH of the suspension after polymerization was 8.5.

Example 3

Linolonic acid at a concentration of 0.08 g per kg of vinyl chloride was used, and the insoluble calcium salt was prepared in situ by the addition of 0.15 g of calcium oxide per kg of vinyl chloride. The resulting polymer had a mean particle size of 112 µm, a bulk density of 502 g / l, a porosity of 0.31 ml / g and an absorption time of 8 minutes.

Example 4

Sorbitanostor fatty acids contained in rapeseed oil were used at a concentration

0.5 g / kg vinyl chloride. The total polymerization time to 86-88% conversion was extended by 70 minutes. The polymer obtained had a mean particle size of 102 µm, a bulk density of 488 g / l, a porosity of 0.32 ml / g and an absorption time of 9 minutes.

Example 5

The same type of nonionic surfactant as in Example 4 was used in a 0.15 g / kg vinyl chloride concentration and oleic acid at a concentration of 0.15 g / kg vinyl chloride. In addition, lead acetate was added in a co-tacitrate of ± 0.5 g / kg of vinyl chloride dissolved in water. After stirring in the aqueous phase containing the emulsifiers, 0.1 g / kg sodium hydroxide was metered in as a one percent aqueous solution. The prepared polymer had an average particle size of 99 µm, a bulk density of 490 g / l porosity of 0.31 m 2 / g and an absorption time of 8 m.nut. The polymerization was not retarded.

Example - 6

The feeds contained in the soybean process, i.e. a mixture of deic acid, lindic acid and lindenoic acid in a concentration of 0.12 g / kg vinyl chloride, were used. After 30 minutes of polymerization at a conversion of about 7%, calcium hytooxide was added to the blend of 0.18 g / kg vinyl chloride in water. The mean polymer particle size was 105 µm, the bulk density was 492 gA, the porosity was 0.32 ml / g, and the absorption time was 7 minutes.

Example 7

Technical oleic acid, about 85 to 87% of dicic acid and 13 to 15% of stearic acid - at a concentration of 0.28 g / kg vinyl chloride, was used. Insoluble salt was prepared in situ by adding 0.1 g magnesium hydroxide and 0.05 g hydroxide Calcium - per kg of vinyl chloride. The polymerization was not retarded. The resulting polymer had a mean particle size of 100 µm, a bulk density of 480 g / l, a porosity of 0.33 ml / g and an absorption time of 8 m.nut. the pH of the aqueous phase after polymerization was 9> 4. If the polymerization was carried out with the same dioic acid at the same concentration but without conversion to the insoluble salt, the polymerization time to 86-88% conversion was extended by 60 minutes. The mean particle size was 106 [mu] d, the bulk density was 535 g / l, the porosity was 0.24 ml / g and the absorption time was 18 minutes. The pH of the aqueous phase after polymerization was 3.4.

Example 8

Dicic acid was used in a concentration of 0.3 gAg vinyl chloride and 211 935 urate at a concentration of 0.2 g / kg vinyl chloride. After 50 minutes of polymerization at a conversion of about%, barium hydroxide was metered in at a concentration of 0.5 g / kg vinyl chloride as an aqueous solution. The mean particle size of the polymer obtained was 99 .mu.m, the bulk density was 490 g / l, the porosity was 0.34 ml / g, and the absorption time was 7 minutes.

Examples 9 to 10.

^S ^ uspenzní polymerization vinylC chloride tulle performed at ^t EPLO ^I 59 ° C, viscosity of the resulting polymer occiput 105-4 ml / g, which is a K-value of 65-1, miromoleikilárních emuugátorů concentration was 1.1 g / kg of vinyl chloride, the concentration of hydrogen peroxide 0.8 m / kg vinyl chloride and a concentration of dimethyl percarbonate of 1.4 m / kg vinyl chloride.

Example 9 stearic and oleic acid mono-diglyceride, iodine number 30, saponification number 180 at a concentration of 1.2 g / kg vinyl chloride. Polymerization time to conversion of 86-88% tulle 340 min. The average polymer particle size was 99 µm, the bulk density was 519 g / l, the porosity was 0.22 ml / g, and the absorption time was 12 minutes. .

Example 10

The oleic acid used was 0.18 g / kg of vinyl chloride, dosed as a solution in vinyl chloride. The aqueous phase contained 0.25 g of oleic acid before dosing the vinyl chloride with oleic acid. The polymerization time to 86-88% conversion was 290 mmin, the polymer had a mean particle size of 97 m, a bulk density of 512 g / l, a porosity of 0.25 ml / g and an absorption time of 8 m.

Example 11

A polymer having a viscosity number of 89-4 ml / g was prepared at 65-66 ° C

The equivalent of the emulsifiers was 0.88 g / kg J of vinyl chloride and the mixture of the initiator dilalroylperoxide - and the di-tert-luУyCckkOokeyyPeckkêcrblcátl was - 2 mu / kg vinyl chloride. 0.05 g / kg of vinyl chloride was used. The insoluble calcium salt was prepared by adding 0.3 g of calcium hydroxide.

211 935 per kg vinyl chloride. The resulting polymer had a bulk density of 560 g / χ and a porosity of 0.16 ml / g. For the preparation of a polymer with the same viscosity number and porosity of 0.16 ml / g, 0.8 g of low-molecular-weight polyvinyl alcohol with an A-oetate group content of over 30%, used as an alcoholic solution, was used instead of calcium ricinoleate.

Claims (1)

Process for the suspension polymerization of vinyl chloride under pressure in a stirred reactor, wherein the monomer is dispersed in the aqueous phase with the addition of polymerization initiators, macromolecular emulsifiers, surfactants and other additives, characterized in that at least 2% by weight surfactants in the polymerization mixture are carboxylic acid salts. 30 carbon atoms and at least one unsaturated bond with cations of two or polyvalent metals ·