FI57959C - FOERFARANDE FOER POLYMERISATION AV VINYLKLORID I MIKROSUSPENSION - Google Patents

Description

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France-France (FR) 7320882 (71) RhÖne-Progil, 25 »Quai Paul Doumer ·, 92¾08 Courbevoie, France-France (FR) (72) Nicolas Fischer, Paris, Jacques Boissel, L'Isle-Adam, Thomas Kemp, Levallois-Perret, Henri Eyer, Ribecourt, France-France (FR) (7¾) Berggren Oy Ab (5¾) Method for the polymerisation of vinyl chloride in microsuspension -Förfarande för polymerisation av vinylklorid i mikrosuspension

The present invention relates to a process for the polymerization and copolymerization of vinyl chloride in a microsuspension. It also targets the resulting polymers and copolymers.

In microsuspension, polymerization means the polymerization of at least one monomer dispersed by strong mechanical aids in an aqueous solution in the presence of organic soluble polymerization initiators and containing an emulsifier or a large amount of protective colloid as a stabilizing agent to give a dispersion in which the dispersion is obtained. Um.

At normal polymerization temperatures, the classical polymerization initiators used in the vinyl chloride polymerization provide polymerization and copolymerization reactions with kinetics that are self-accelerating in nature, which makes it difficult to use both in order for the poly- 2 57959 immersion rate to be satisfactory on an industrial scale.

To overcome these disadvantages, it has been proposed to use polymerization initiators which degrade more rapidly, but it has been found that these substances do not give good results when polymerizing in a microsuspension. It has also been suggested that the decomposition of polymerization initiators be accelerated by the use of transition metal salts in solution, especially at low temperature polymerization, to obtain vinyl chloride polymers having a very high molecular weight and / or crystalline structure; however, the kinetics of the reaction are self-accelerating.

It is further known that the use of an inoculant in the microsuspension polymerization, which contains the initiator required for the polymerization, can practically completely prevent the formation of shells in the reactor and partially control the self-acceleration of the reaction, especially when the proportion of inoculum is considerable; nevertheless, this improvement is only limited.

The process according to the invention avoids the self-acceleration phenomenon as well as all the disadvantages associated therewith, and enables the polymerization or copolymerization of vinyl chloride in microsuspension at conventional temperatures, with the highest possible reaction rate using certain equipment, the formation of shells is minimal and thus the reactor is used optimally.

The invention therefore relates to a process for the preparation of homopolymers and copolymers of vinyl chloride, in which the polymerization of the monomer or monomers is carried out in a microsuspension at a temperature of 30-70 ° C in the presence of a seed dispersant is from 0.05 to 2 .mu.m, they contain from 0.1 to 5% by weight, based on the polymer, of the organic soluble peroxide initiator required for polymerization, and from 0.5 to 10% by weight, based on the sum of the monomer or monomers and the seed polymer, and is characterized in that the initiator is activated by an organo-soluble metal complex which is either formed during the polymerization by a reaction between a water-soluble metal salt and a progressively added complexing agent during polymerization 3,5959, or is prepared in advance from a water-soluble metal salt and a complexing agent. reaction and is added gradually, keeping the molar ratio of metal salt / initiator between 0.1 and 10.

More specifically, the metals used are iron, copper, cobalt, nickel, zinc, tin, vanadium, manganese, chromium, silver. They are used as water-soluble salts such as sulfates, chlorides, nitrates, acetates.

These salts can be introduced into the reaction zone before or during the polymerization.

The complexing agents used are compounds which convert the metal from its water-soluble form to soluble in vinyl chloride, have no polymerization-inhibiting effect of any kind, and do not prevent the metal from activating the polymerization initiators.

Substances that meet such conditions include monocarboxylic acids that are sparingly soluble in water, such as perfluorobutyric acid, α-bromilauryl acid, sulfosalicylic acid, naphthenic acid, caprylic acid, polycarboxylic acids such as succinic acid, tartaric acid, and dihydric acid; alkyl phosphoric acids such as di (2-ethyl) hexyl phosphoric acid; lactones such as ascorbic acid and its esters, γ-butyric acid lactone; ketones having groups in position a or β which activate the action of carbonyl such as acetylacetone, dihydroxy-1,3-acetone, benzoin; carbazones such as diphenylthiocarbazone.

The proportion of complexing agent depends on the polymerization temperature, the cooling capacity of the reactor and the purity of the reactants. The amount can increase to a stoichiometric molar ratio to the metal salt.

This complexing agent, together with the metal salt in solution, forms an organic soluble complex, whereby the metal enters an organic phase where it activates the polymerization-initiating substance. Thus, the initiators can be activated as desired by varying the amount of complexing agent and the time at which it is added to the reaction zone, and thus the kinetics of the polymerization reaction can be adjusted at any time. The polymerization is slow in its initial stage without the use of an alkylating agent, but in the process it is strongly activated initially, then less ί 57959 and less according to the progress of the reaction. Thanks to the optimal utilization of the cooling capacity of the reactor, polymerization can thus be carried out in a minimum time.

This goal is not achieved if the entire amount of complexing agent is added at the outset. In that case, the activation of the polymerization initiator is too rapid at the beginning of the polymerization. The polymerization initiator then decomposes too quickly, and the reaction cannot proceed to completion in the absence of the initiator.

According to a variant of the process according to the invention, the polymerization initiator is activated by progressively introducing an organol-soluble metal complex prepared in advance by reacting the metal salts and the complexing agents listed above.

These complexes are used in such proportions that the molar ratio of the metal complex to the polymerization initiator is 0.1 to 10.

The activating effect of the complex on the polymerization initiator can be interrupted at any time by stopping the addition of the complexing agent or complex and / or allowing the metal ion to return from its organic soluble form to its water-soluble form; this is easily accomplished by adding to the reaction zone a sequestering agent, such as an alkali metal salt of acids such as ethylenediaminetetraacetic acid, which in addition to ethylenediaminetetraacetic acid are represented by e.g. ethylenediamine-triacetic acid. The sequestering agent is used in a ratio that can even be a stoichiometric molar ratio to the metal salt.

The inoculum required for the polymerization is prepared according to the classical technique used in the microsuspension polymerization. For example, water, vinyl chloride with or without a comonomer, an anionic emulsion-forming agent and an organic-soluble polymerization initiator are used. The monomer or monomers are dispersed in water into very fine particles by means of a powerful mechanical means, such as a colloid mill, a high-speed pump, a vibratory mixer, an ultrasonic device. The resulting microsuspension is then heated under autogenous pressure and with stirring at a quieter rate at a temperature adjusted to the molecular weight of the product to be obtained.

The inoculum is in the form of a dispersion of polymer or copolymer particles and has a particle diameter of between 0.05 and 2 microns.

In order to carry out the process according to the invention, the inoculum particles must contain the entire amount of initiator required for the polymerization according to the invention. This amount is 0.1 to 5% by weight, based on the polymer of the inoculant, and is introduced into the reactor before the polymerization of said substance.

Monomer-soluble polymerization initiators include organic peroxides such as diacyl peroxides, which include lauryl peroxide, decanyl peroxide and caprylic peroxide.

The amount of inoculant used in the polymerization according to the invention must be such that the polymer contained therein is from 0.5 to 10% by weight, based on the sum of the monomer or monomers to be polymerized + the inoculating polymer.

The amount of polymerization initiator present in the solution, relative to the monomer to be polymerized, is thus very small compared to known methods.

Even larger amounts of inoculant can be used, for example those containing more than 10% polymer, but this is of little use, since the amount of polymer is then very considerable relative to the monomer or monomers and the advantages of the process are thus reduced.

The presence of the inoculant in the reaction zone is sufficient to cause the monomer to disperse without the need for a new vigorous dispersion of the zone.

The monomers copolymerizable with vinyl chloride are those commonly used in the classical vinyl chloride copolymerization technique. Mention may be made, for example, of vinyl esters of mono- and polycarboxylic acids, such as vinyl acetate, vinyl propionate, 6 57959 vinyl benzoate; aliphatic, cycloaliphatic and aromatic esters, amides and nitrile allyl, vinyl, vinylidene halides of unsaturated mono- or polycarboxylic acids such as acrylic, methacrylic, maleic, fumaric acid; alkyl vinyl ethers; olefins. The proportion of comonomer can be up to 25% of the copolymer.

In order to improve the stability of the microsuspension, it may be advantageous to add up to 2% by weight of anionic emulsifier relative to the monomer or monomers before and / or during the polymerization. This emulsifying agent may be the same or the same as those used in the preparation of the inoculum. It is selected from classical products such as: fatty acid soaps, alkyl sulfates, alkyl sulfonates, alkyl aryl sulfonates, alkyl sulfosuccinates, alkyl phosphates.

Optionally, a non-ionic surfactant such as condensation products of ethylene or propylene oxides with various organic hydroxyl-containing compounds can be combined with this emulsion-forming agent.

The amount of water used in the polymerization process according to the invention must be such that the weight ratio of monomer (s) + polymer / water of the inoculant (which also includes the water contained in the inoculant) is 0.3-1.5.

The polymerization temperature, which depends on the quality of the polymer to be obtained, is usually 30 to 70 ° C.

The process according to the invention is particularly suitable for the continuous polymerization described in French Patent No. 1 ^ 85 5 ^ 7 in the name of Peehiney-Saint-Gobain. In this case, by adding a complexing agent or complex, the optimal reaction kinetics can be maintained and thus a constant and high degree of change can be ensured.

The present invention also relates to vinyl chloride polymers and copolymers prepared according to the above process, which can be isolated from the polymerization zone by all known methods, such as filtration, coagulation and drying by centrifugation, peeling, centrifugation, spraying.

Polymers and copolymers can be used for the production, extrusion, extrusion blow molding, injection molding, casting of sheets, films, yarns, hollow objects, porous materials, articles compressed in a matrix; as well as for the manufacture of surface-brushed garments, for the manufacture of porous materials and molded articles using all known techniques using plastisols: surface lubrication, rotational molding, dipping.

The following are illustrative examples of the practice of the invention; however, they are in no way restrictive.

Example 1

A 25 m 2 reactor equipped with a stirrer is charged with 1212,000 kg of water, 12001200 kg of grafting product prepared by polymerization in a micro-suspension at a concentration of 33.3%, i.e. 400 kg of polyvinyl chloride containing 6 kg of lauryl peroxide and having an average particle diameter of 0.4 to 60 kg of sodium dodecylbenzene sulphonate, - 0.5 kg of copper sulphate, - 10 000 kg of vinyl chloride.

It is then heated to 52 ° C under autogenous pressure and the temperature is maintained throughout the reaction.

After the temperature in the reaction zone is 52 ° C, an aqueous solution of ascorbic acid containing 4 g / l is added. Its feed rate, expressed as weight of acid, is 65 g / t for 3 hours, then 45 g / t for 3 hours and finally 20 g / t until the end of the reaction.

After 9 hours, a typical pressure drop is observed after the reaction is complete. The addition of ascorbic acid is stopped and the unreacted monomer is removed as a gas.

22,200 kg of polymer dispersion with a concentration of 42.2% by weight are obtained; i. the actual rate of change is 89.7% by weight of the vinyl chloride used.

8 57959

The thin polymer film on the reactor walls represents no more than 0.1% by weight of the vinyl chloride used.

The average diameter of the obtained particles is 1.1 μm. After spraying and grinding, the polymer obtained has a viscosity index of 130, measured according to French standard T 51-013.

The viscosity of plastisol prepared by mixing 100 parts by weight of the obtained polyvinyl chloride and 60 parts by weight of dioctyl phthalate, measured with a Brookfield RTV viscometer (needle No. 7-20 T / mn), is 20 poise.

For comparison, in order to better demonstrate the cost-effectiveness of the process, various experiments according to the former method are performed.

A) Polymerization in microsuspension, without inoculant and without activation.

In the same reactor as in Example 1 are charged: -12,000 kg of water, 8 kg of lauryl peroxide, 100 kg of sodium dodecylbenzene sulfonate, -10,000 kg of vinyl chloride.

The mixture is homogenized to obtain a microsuspension with an average grain size of the organic phase of 1. It is then heated to 52 ° C under autogenous pressure and this temperature is maintained throughout the reaction.

The rate of the reaction is irregular, initially very slow, then accelerates, and for the last two hours the reactor must be cooled to a maximum. After 18 hours, the reaction is complete. The unreacted monomer is removed as a gas to give 20,300 kg of a dispersion with a concentration of ^ 1% by weight, which corresponds to a degree of change of 83% by weight, based on the vinyl chloride used. The shells formed on the reactor walls are 1% by weight of the vinyl chloride used.

The following graph shows the development of the polymerization rate in Example 1 (Curve 1) and Experiment A (Curve 2).

Polymerization rate

It is found that compared to the process according to the invention, and although the amount of polymerization initiator is higher, the reaction time is 2 times longer, the degree of conversion is worse and the number of shells is 10 times higher.

B) Polymerization in the microsuspension, using inoculum, was not activated.

Example 1 is repeated, but neither copper sulfate nor ascorbic acid is introduced into the reactor.

After 15 hours of reaction, 22,000 kg of dispersion with a concentration of 40.5% by weight, i.e. the rate of change is 85.1% by weight based on the vinyl chloride used.

Shells corresponding to 0.6% by weight of the vinyl chloride used are recovered from the reactor walls.

The average diameter of the obtained particles is 1.08 μm.

Compared to Example 1, it is found that the activation of the polymerization initiator according to the invention makes it possible to carry out the reaction in 9 hours instead of 15 hours, improves the rate of change by 4% and reduces the number of shells formed 6-fold.

C) Polymerization in the microsuspension, neither inoculum nor activated, polymerization initiators were used which decompose rapidly.

10 57959 A reactor with a stirred capacity of 120 liters is charged with: - 60 kg of water, - 0.160 kg of lauryl peroxide, - 0.120 kg of isopropyl percarbonate, - 0.4 kg of sodium dodecylbenzene sulphonate, - 40 kg of vinyl chloride.

The mixture is homogenized to obtain a microsuspension with an average grain size of 1 in the organic phase.

It is then heated to 52 ° C under autogenous pressure and this temperature is maintained throughout the reaction.

After 12 hours of reaction, a coarse dispersion containing a lot of coagulates is obtained. In addition, the shells formed on the reactor walls are 30% of the monomer used.

Example 2

Example 1 is repeated using an inoculum having an average particle diameter of 0.25 μm and polymerized at 42 ° C.

After 12 hours, 22,100 kg of polymer dispersion with a concentration of 42.4% by weight, i.e. the actual conversion is 89.7% by weight based on the vinyl chloride used.

The average diameter of the obtained particles is 0.6.

The viscosity index of the polymer is 180.

Plastisol, prepared by mixing 100 parts by weight of the vinyl polychloride obtained and 60 parts by weight of dioctyl phthalate, has a viscosity of 75 poise.

Example 3

Work as in Example 1, but instead of 10,000 kg of vinyl chloride, 9,300 kg of vinyl chloride and 700 kg of vinyl acetate are used.

After the reaction of 11.5 7 9 5 9 9.5 hours, 22,400 kg of copolymer dispersion are obtained, containing 4.9% of vinyl acetate at a concentration of 42.6% by weight, i.e. the actual rate of change is 91.4% by weight based on the monomer used.

The resulting particles have an average diameter of 1.1 μm.

The copolymer has a viscosity index of 130. A plastisol prepared by mixing 100 parts by weight of the co-polymer obtained and 60 parts by weight of dioctyl phthalate has a viscosity of 30 poise and a gel formation temperature of 144 ° C, measured by the Heinrichs method described in in Modern Plastics, April 1964, page 165.

^ Example 4

The same reactor as in Example 1 is charged with: 12,600 kg of water, 1,070 kg of inoculant at a concentration of 39%> i.e. 417.3 kg of polyvinyl chloride containing 6.3 kg of lauryl peroxide and having an average particle diameter of 0.4 μm.

- 84 kg of sodium dodecylbenzene sulphonate, - 8 400 kg of vinyl chloride, - 0,42 kg of copper sulphate.

Heat to 52 ° C and progressively add 840 g of dihydroxymaleic acid over 12 hours, i.e. 105 g / h for 4 hours, then 65 g / h for 4 hours and finally 40 g / h for 4 hours.

20,970 kg of a polymer dispersion with a concentration of 36.9 m.p. the rate of change is 87.1% by weight based on the monomer used. A film of 0.12% by weight of the vinyl chloride used is obtained from the walls of the reactor. The average diameter of the obtained particles is 1.1 μm.

Example 5

Example 4 is repeated, but dihydroxymaleic acid is replaced with succinic acid.

After 14 hours of reaction, 21,070 kg of a polymer dispersion with a concentration of 37% are obtained, i.e. rate of change 87.8%. The weight of the shells 12 57959 is not more than 0.15% by weight, calculated on the polyvinyl chloride used.

The average diameter of the particles is 1.08 μm.

Example 6

Work as in the example but replace the copper sulphate and dihydroxymaleic acid with 840 g of vanadium acetylacetonate.

The latter compound is progressively added to the reaction zone at a temperature of 52 ° C for 12.5 hours, 105 g / h for 4 hours, then 65 g / h for 4 hours and finally 40 g / h for 4.5 hours.

20870 kg of polymer dispersion are obtained with a concentration of 36.5% »i.e. the rate of change is 85.5% - The number of shells is 0.18% by weight of the monomer used.

The average particle diameter is 1.09 μm.

Example 7

Several experiments were performed using different activating agents under the following conditions: after placing in a 200 ml glass bottle after suction emptying and then removal of gaseous vinyl chloride, - non-ionised water 60 ml - polymerization inoculum in a micro-suspension with a concentration of 34 , 9 ί, so. 3 g of polyvinyl chloride containing 0.04 g of lauryl peroxide and having an average particle diameter of 0.4 μm 10.5 g - sodium dodecylbenzene sulphonate 0.18 g - vinyl chloride 30 g

. . . . . . -S

- an activating agent consisting of either 10 x 10 J mol -5 metal salts and 5 x 10 mol mol complexing agent, or 10 x 10 J molar metal complex prepared in advance.

The flask is then sealed, placed in a water bath set at 52 ° C, and the flask is moved back and forth. Continue in this way for 5 hours and then cool the flask, degas it, evaporate the water and give the polymer formed.

The activators used as well as the results obtained are shown in the following table.

Experiment Metal salt Complexing polymer Weight percent by weight based on vinyl chloride A, control experiment 0 Copper sulphate sulfosalicylic acid 16 C "naphthenic acid 3 D octanoic acid (caprylic acid) 3.

_ e menic acid if, 4 F "tartaric acid 16 G u maleic anhydride 4.1 H di (2-ethyl) -hexyl-phosphoric acid 10.2 L" ascorbic acid 23 J "γ-butyric acid lactone 14 K" benzoin 2.8 L "diphenylthiocarbazone 3 M ferrous sulphate ascorbic acid 23 N nickel sulphate "20 0 zinc sulphate" 25 P vanadium sulphate "59 Q manganese sulphate" 12 R chromium sulphate "23 S stannous chloride" 33 T cobalt nitrate "10 U silver nitrate" 6 U silver nitrate " 6.9 This table shows excellently the effect of activators on the onset of polymerization.

Claims (5)

14 5 7 9 5 9 A process for the preparation of homopolymers and copolymers of vinyl chloride, wherein the polymerization of the monomer or monomers is carried out in a microsuspension at a temperature of 30-70 ° C in the presence of a seed dispersion of a dispersion of vinyl chloride homo- or copolymer particles is 0.05-2 / Um, they contain 0.1-5 weight? calculated from the polymer to the organololuble peroxide initiator required for polymerization, and in an amount of 0.5 to 10% by weight? calculated from the sum of the monomer or monomers and the seed polymer, characterized in that the initiator is activated by an organololuble metal complex either formed during the polymerization by a reaction between a water-soluble metal salt and a progressively added complexing agent or pre-prepared with a water-soluble metal salt and a complexing agent , wherein the molar ratio of metal salt / initiator is kept between 0.1 and 10. Process according to Claim 1, characterized in that the metal salt used is an iron, copper, cobalt, nickel, zinc, tin, titanium, vanadium, manganese, chromium or silver salt. Process according to Claim 1, characterized in that the complexing agents are monocarboxylic acids, polycarboxylic acids, alkylphosphoric acids, lactones, ketones or carbazones. Process according to Claim 1, characterized in that the complexing agent is used up to a stoichiometric molar ratio to the metal salt. Process according to Claim 1, characterized in that the activation is stopped by stopping the addition of the complexing agent or complex and / or by adding a sequestering agent, for which alkali salts of acids such as ethylenediaminetetraacetic acid can be selected.