FI61706B - FOERFARANDE FOER POLYMERISERING AV VINYLKLORID I MIKROSUSPENSION I VILKEN INGAOR YMPMEDEL SAMT SAO FRAMSTAELLD LATEX - Google Patents

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France-France (FR) 75135Ö2 (71) Chloe Chimie, Tour Gänerale, 5, Place de la Pyramide, Quartier Villon,, F-928OO Puteaux, France-France (FR) (72) Thomas Kemp, Levallois-Perret, France- Frankrike (FR) (74) Berggren Oy Ah (54) Method for polymerisation of vinyl chloride in a microsuspension containing a grafting agent and a latex thus prepared - Förfarande för polymerisering av vinylklorid i microsuspusp,

The invention relates to a process for the preparation of polyvinyl chloride and copolymers of vinyl chloride by polymerization in a microsuspension containing a grafting agent. The invention also relates to a polyvinyl chloride and copolymer latex thus obtained.

By polymerization in a micro-suspension, i.e. a very fine suspension, is meant the polymerization, using substances which initiate organic reactions, of at least one monomer dispersed by very strong mechanical means in an aqueous solution containing an emulsifier to stabilize the mixture, so that the result is a particle dispersion with an average diameter of less than 5 μm.

Finnish Patent No. 46,074 discloses a process for the preparation of vinyl chloride polymers in a microsuspension using a grafting agent which contains all the reaction initiators required for the polymerization. However, when the polymerization is carried out so that the polymer concentration of the resulting latex is more than 45%, the high viscosity of the mixture forces mixing very slowly, 2 617 0 6 because the latex formed by it is mechanically unstable. This slow mixing causes a decrease in the reaction rate, which is why the polymerization time must be increased.

In addition, when the obtained polymers are used for the preparation of plastisols, the latter are difficult to use due to their expansion, i. because their viscosity increases as the rate gradient increases, and because the upper limit of the plasticizer used is 50 parts per 100 parts of polymer.

It is also known from Finnish patent 57 959 to prepare vinyl chloride polymers in microsuspension in the presence of a grafting agent in the form of a particle dispersion of a vinyl chloride homopolymer or copolymer prepared in advance in a microsuspension. with a tallow complex prepared in advance or in situ by reacting a water-soluble metal salt with a gradually added complexing agent. This method makes it possible to reduce the amount of initiator used and to increase the polymerization rate. However, plastisols made from polymers obtained by this method are difficult to use due to their swelling.

It is also known that in the case where vinyl chloride polymers are prepared by polymerizing in an emulsion, i.e. in the presence of a solution of a water-soluble initiator in an aqueous medium, the performance of the plastisol is improved if the polymer is composed of elementary particles of at least two populations. This plurality of populations is achieved by mixing several latexes with different particle granulometry, but this mixing cannot be accomplished at high concentrations. Another solution described in GB Patent 928,556 is to simultaneously prepare different particle populations by polymerizing at least one monomer in an emulsion and using multiple grafting agents prepared by polymerizing in an emulsion; however, this method is very difficult because the amount of emulsifier used must be well defined and limited and its addition requires precautions, i. each time a certain amount of addition to avoid nucleation of new particles, which limits the polymer concentration of the latex obtained. In addition, it is difficult to produce grafting agents with very small, calibrated, and homogeneous particle sizes, and even the slightest variation in their granulometry causes a change in key dimensional ratios and proportions of different populations obtained after polymerization.

The process according to the invention avoids these inconveniences and can be prepared without limitations, precautions and difficulties by polymerizing in the micro-suspension latexes with a polymer concentration well above 45% by weight, with low viscosity and completely similar granulometry. In addition, the polymers thus obtained can be easily handled and are particularly suitable for plastisols which contain very little plasticizer but are still easy to use.

The invention therefore relates to a process for the preparation of copolymers comprising polyvinyl chloride or at least 50 parts by weight of vinyl chloride and at least one copolymerizable monomer, in which process the corresponding monomers are polymerized in a microsuspension in the presence of a grafting agent , consisting of vinyl chloride homopolymers, vinyl chloride copolymers having one copolymerizable monomer, and homopolymers and copolymers of copolymerizable monomers prepared by pre-polymerizing and the process according to the invention is characterized in that the polymerization is carried out in the presence of one or more other grafting agents which are vinyl polymers. in the form of dispersions of particles in which the particle sizes are different from each other and from the first grafting agent, the total amount of grafting agents used being such that the amount of polymers contained is 1-50% by weight of the sum of polymerizable vinyl chloride and grafting polymers. - 'r. · /.

“61706 for graft polymers is 95/5 to 5/95 and the concentration of graft polymers and vinyl chloride or a mixture of vinyl chloride and copolymerizable monomer, taking into account the water content of the grafting agents, is 20 to 80% by weight of the reaction mixture.

The monomers copolymerizable with vinyl chloride are the same as those commonly used in classical vinyl chloride copolymerization methods. Mention may be made of vinyl esters of mono- and polycarboxylic acids such as vinyl acetate, propionate, benzoate; unsaturated mono- and polycarboxylic acids such as acrylic, methacrylic, maleic, fumaric, itaconic acid, as well as their aliphatic, cycloaliphatic, aromatic esters, their amides, their nitriles; vinyl halides, vinylidene halides; alkyl vinyl ethers; olefins.

The vinyl polymers of which the grafting agents are composed are represented by the vinyl chloride polymers as defined above, as well as homopolymers of the above-mentioned copolymerizable monomers or copolymers formed from said monomers.

The different polymers of grafting agents used in the same work may be identical or different.

The use of a vinyl polymer other than vinyl chloride as a grafting agent can improve certain mechanical properties or the suitability of the resulting polymers for use, for example, in extrusion or mangling.

The primary grafting agent required for polymerization is prepared in a micro-suspension according to the classical polymerization technique.

It is in the form of a dispersion of polymer particles in which the average diameter of the particles is between 0.05 and 1.5 μm, preferably between 0.2 and 1 μm.

One way to prepare the first grafting product is to use water, a vinyl monomer or a mixture of vinyl monomers, an organo-soluble initiator and an anionic emulsifier, optionally with the addition of a non-ionizable emulsifier. The monomer or monomers are dispersed into very fine particles in water by means of a powerful mechanical means such as using a colloid mill, a high-speed pump, a vibration mixer, an ultrasonic device. The resulting microsuspension is then heated under autogenous pressure and with moderate agitation at a temperature usually between 30-65 ° C. When the pressure has dropped, the reaction is stopped and gas is released from the unchanged monomer or monomers.

Organic peroxides such as diacyl peroxides, which may be mentioned as lauryl, decanyl, caprylic peroxides, tert-butyl diethyl peracetate, diethyl hexyl percarbonate, diacetyl peroxide, are representative of the initiators used in the preparation of the grafting agent.

The choice of organic soluble initiator depends on its rate of decomposition at the reaction temperature used. Said initiator must be sufficiently reactive so that normal doses, about 0.1 to 3% by weight of the monomer or mixture of monomers, are sufficient to prepare the grafting agent within about 4 to 20 hours. However, the rate of decomposition of the initiator must not be too high so that the amount of initiator decomposed in the preparation of the grafting agent exceeds half the amount of initiator used. Therefore, it is necessary to select a substance having a half-life such that the amount of decomposed initiator during the preparation of the grafting agent is 5 to 50% by weight of the total initiator used.

In the case of the use of several initiators for initiating organic soluble reactions, it is preferable to select them from those having a different reactivity; the most reactive of them react primarily during the preparation of the grafting agent, while the least reactive react specifically during the graft polymerization of vinyl chloride or a mixture of vinyl chloride copolymerizable vinyl monomer.

The other or other grafting agents are in the form of polymer particle dispersions, which may or may not contain a reaction initiator, and whose average diameters, which differ from each other and from the average diameters of the first grafting agent, are between 0.02 and 1.5 μm and preferably between ^ 0.02 to 0.8 microns. For example, in the case where there are only two grafting agents, the particles of the second grafting agent have an average diameter of between 0.05 and 15 and preferably between 0.05 and 0.8; and in the case where there are three grafting agents, the average diameter of the particles of the second grafting agent is between 0.05 and 1.5 μm and preferably between 0.05 and 0.8 μm, and the average diameter of the particles of the third grafting agent is between 0.02-0 , 8 μm and preferably between 0.02-0.5 μm.

These particle dispersions can be prepared in microsuspension and emulsion according to classical methods used in polymerization.

The preparation of a grafting agent other than the first grafting agent, when carried out by polymerization in a microsuspension, is carried out as described above, but the homogenization takes place even more thoroughly if the particles obtained are very small in size. In the process of the invention, it is usually more advantageous to use, in addition to the first grafting agent, one or more grafting agents which do not contain a reaction initiator. Their polymerization is then carried out using an amount of the initiator such that at least 80% by weight of said initiator decomposes during the reaction.

The preparation of a grafting agent other than the first grafting agent, when carried out in an emulsion by polymerization, comprises the use of water, vinyl monomer either alone or in combination with a copolymerizable monomer, a water-soluble initiator and an anionic emulsifier optionally with a non-ionizable emulsifier. .

•,

The size of the particles is controlled by conventional methods suitable for emulsion polymerization, such as carefully selecting the nature and amount of emulsifier used, using a grafting agent, and controlling the mixing rate.

The reaction mixture is heated under autogenous pressure and stirred moderately at a temperature in the range of 30-65 ° C. When the pressure has dropped, the reaction is stopped and gas is released from the unchanged or unchanged monomers.

The water-soluble reaction initiators required for the preparation of grafting agents are usually hydrogen peroxide, alkali metal or ammonium persulfates, with or without the addition of water-soluble reducing agents such as alkali metal sulfites or bisulfites. The amounts used, very different, depend on the system initiating the chosen reaction and are just large enough to ensure that the polymerization takes place within 4-10 hours.

The total amount of different grafting agents used in the polymeric composition according to the invention must be such that the amount of polymer they contain represents from 1 to 50% by weight of vinyl chloride with or without the comonomer to be polymerized + grafting polymers. An amount of grafting polymers of more than 50% by weight can be used, but this is of little use, since the amount is very considerable relative to the vinyl chloride or mixture of vinyl chloride copolymerizable monomer, and the advantages of the process according to the invention are thus reduced. The amount of grafting polymers of less than 1 # is also of little use, since the amount of initiator contained in the first, two or more grafting polymers is then very small and no longer provides virtually no vinyl chloride or mixture of vinyl chloride copolymerizable monomer. polymerization. In fact, the excessly used organololuble initiator in the first, two or more grafting polymers very effectively initiates the polymerization of the vinyl chloride or mixture of vinyl chloride copolymerizable monomer and gives the reaction a regular rate, as shown in Finnish Patent No. 46,074.

The ratio of the amount of the first graft polymer to the second or other graft polymers, which is a function of the structure of the resulting polymer, is between 95/5 and 5/95.

8 61 706 Thus, in the implementation of graft polymerization, several different possibilities are allowed. For example: A first grafting agent prepared in a microsuspension by polymerization, the polymer particles of which contain an organolysing initiator, and a second grafting agent prepared by polymerizing in an emulsion or microsuspension, the polymer particles of which are smaller than the first grafting agent, are used. or a second grafting agent prepared by polymerizing in a microsuspension having polymer particles smaller than the first grafting agent and containing an organoluble reaction initiator.

A first grafting agent is prepared by polymerizing in a microsuspension, the polymer particles of which contain a initiator, and a second grafting agent prepared by polymerizing in an emulsion or a microsuspension, the polymer particles of which are larger than the first grafting agent, do not contain a reaction. a grafting agent prepared by polymerizing in an emulsion or microsuspension and having polymer particles smaller than that of the second grafting agent and not containing a reactant, or a third grafting agent prepared by polymerizing the agent in a microsuspension and having polymer particles smaller than another grafting agent .

A first grafting agent prepared by polymerizing in a microsuspension, the polymer particles of which contain an organoluble initiator, and a second grafting agent prepared by polymerizing in a microsuspension, the polymer particles of which are smaller than the first grafting agent and containing an organoluble reaction, are used. is prepared by polymerization in an emulsion or microsuspension, and the polymer particles of which are smaller than the second grafting agent and do not contain a reaction initiator, or a third grafting agent prepared by polymerizing in a microsuspension and the polymer particles of which are smaller than the second grafting agent.

9 617 O 6 A first grafting agent prepared in a microsuspension by polymerization, the polymer particles of which contain a reaction initiator, and a second grafting agent prepared by polymerization in an emulsion or microsuspension, the polymer particles of which are larger than the first grafting agent, are used. .

A first grafting agent prepared by polymerization in a microsuspension, the polymer particles of which contain an organoluble solubilizer initiator, and a second grafting agent prepared in an emulsion or microsuspension, the polymer particles of which are larger than the first grafting agent, and do not contain a reaction initiator, are used. is prepared by polymerization in a microsuspension and has polymer particles larger than the first grafting agent and containing an organolysing reaction initiator, and a third grafting agent prepared by polymerizing in an emulsion or microsuspension and having polymer particles larger than the second grafting agent and not containing the grafting agent.

A first grafting agent is prepared by polymerizing in a microsuspension, the polymer particles of which contain an organolysing initiator, and a second grafting agent prepared by polymerizing in an emulsion or microsuspension, the polymer particles of which are smaller than the first grafting agent and do not contain is prepared by polymerization in an emulsion or microsuspension and has polymer particles larger than the first grafting agent and does not contain a reaction initiator.

In a preferred form, a grafting agent prepared by polymerization in a microsuspension, the polymer particles of which contain a reaction initiator, and a grafting agent prepared by polymerization in an emulsion, the polymer particles of which are smaller than the first grafting agent and do not contain a reaction initiator, are used.

The proportions of grafting agents relative to each other and the total amount of grafting agents · are selected such that the amount of organic soluble initiator contained in the polymer particles would be sufficient to effect polymerization or copolymerization without the addition of additional initiating agent.

The amount of water required for the polymerization according to the invention must be such that the initial concentration of grafting polymers + vinyl chloride with or without copolymerizable monomer, taking into account the water contained in the grafting agents, is between 20-80% and preferably between 45-75% by weight of the reaction mixture.

To improve the stability of the microsuspension, it may be advantageous to add at least one anionic emulsifier before and / or during the polymerization, optionally to which at least one non-ionizable emulsifier has been added. The anionic emulsifiers are preferably fatty acid soaps, alkyl sulphates, alkyl sulphonates, alkyl aryl sulphonates, vinyl sulphonates, allyl sulphonates, alkyl sulphonoxides, polysiloxides, ethylene oxide oxides, non-ionisated alkyl phosphates, and non-ionised substances. This emulsifier may be the same or the same as those used in the manufacture of grafting agents.

The amounts of emulsifier can be up to 5% by weight based on the weight of the vinyl chloride or vinyl chloride copolymerizable monomer of the mixture. These amounts are usually used to make the effect effective on the reaction. However, even if amounts exceeding the limits defined above are used, the scope of the invention remains, since the emulsifiers are only intended to stabilize the microsuspension and do not affect the particle granulometry.

The reaction mixture is heated under autogenous pressure at a polymerization temperature determined by the molecular weight dependent properties of the desired vinyl chloride polymer. This temperature is usually between 10-85 ° C and preferably between 30-70 ° C.

In order to accelerate the polymerization rate, it is advisable to activate the reaction initiator contained in the first and / or second grafting agents with an organoluble metal complex formed during polymerization in a reaction between a water-soluble metal salt and a gradually added complexing agent, as described in that the molar ratio of metal salt / reactant is between 0.1 and 10, and the metal may be iron, copper, cobalt, nickel, zinc, tin, titanium, 11 61706 vanadium, magnesium, chromium, silver. The complexing agent may be mono- or polycarboxylic acids, alkylphosphoric acids; lactones; ketones; carbazones and can even be used in a stoichiometric molar ratio to a metal salt.

It is clear that the polymerization in the microsuspension, as the method described above, can also take place as a continuous process.

The process according to the invention has considerable advantages, such as: the use of the initiator is minimal, the reaction is more regular and possibly shorter than in classical processes, practically no deposits form in the reaction zone, which facilitates heat exchange, so that the polymerization is homogeneous. In addition, the process has the special advantage that high polymer concentrations, namely up to 75% by weight and good flowability, can be achieved in the microsuspension, so that the concentration is between 20 and 75% by weight, and as a result the polymerization and separation equipment can be better utilized. and reproduces the granulometry of the particles contained in the resulting latexes with exceptionally accurate accuracy.

The latices prepared by the process of the invention contain at least two populations of particles with different average diameters. Thus, when two grafting agents are used, the average diameters of the two populations obtained are 0.4 to 2.5 μm for the largest particles, 0.08 to 1 μm for the smallest, and the diameter ratio is 1 to 20 and the weight ratio is 0, 1-10.

When three grafting agents are used, three populations are obtained with average diameters of 0.4-2.5 μm for the largest particles, 0.15-1 / μm for medium-sized particles and 0.05-0.4 μm for the smallest particles, and large dimer ratio ratios. the particles / medium-sized particles and the medium-sized particles / small particles are either the same or different being 1-20, and the weight ratios of the large particles / medium-sized particles and the medium-sized particles / small particles are either the same or different being 0.1-20.

The diameters and weight ratios, within the limits described above, are selected depending on the conditions of use of the polymers formed, such as the rheological properties of the plastisols or their suitability for extrusion.

61706

The particles, which differ in their average diameter, are due to the increase in the particles of the grafting agents. To the best of our knowledge, the particles of grafting agents containing the initiator should grow as described in Finnish Patent No. A6 07 ^; in contrast, the particle growth of grafting agents that do not contain the initiator should be equal to zero. However, the applicant has stated that the growth of the initiator-containing particles is lower than expected, while the growth of the non-reactant-containing particles is not negligible, although it is relatively lower than that of the initiator-containing particles; this growth does not correspond to the laws of polymerization in microsuspension or emulsion.

The vinyl chloride polymers prepared according to the invention are separated from the polymerization mixture by known methods such as filtration, precipitation-centrifugation, cleavage, decantation by centrifugation, decomposition.

The polymers thus obtained, in the form of powders, are particularly well suited for the preparation of plastisols which are Newtonian in nature or pseudoplastic and in which the amount of plasticizer is very small, up to only 25 parts by weight of plasticizer per 100 parts by weight of polymer, and viscosity weak, so brushing can be done very quickly.

The polymers and copolymers of the invention can be used to make sheets, films, yarns, hollow bodies, cellular materials, matrix extruded articles, extruded, extruded-blown, injection molded, molded articles; as well as brushed coatings, cellular materials, for the manufacture of articles molded according to known methods in the use of all plastisols, such as brushing, rotational molding, tempering.

The following are some examples of embodiments to illustrate the invention.

61 706 13

Example 1

Preparation of graft latex 1 in microsuspension Mix: 40 kg of vinyl chloride, 0.6 kg of lauryl peroxide, 4 kg of an aqueous solution containing 10% by weight of sodium dodecylbenzene sulfonate, water in an amount such that the concentration of vinyl chloride is 43% by weight.

This mixture is homogenized to obtain a microsuspension, after which said microsuspension is placed in a 120 l autoclave. It is then heated to 52 ° C under autogenous pressure.

When the pressure has dropped, i.e. After 9 h, the unreacted vinyl chloride is vented. A latex with a polyvinyl chloride concentration of 40% by weight and an average particle diameter of 0.4 .mu.m and containing 1.5% by weight of the polymer of lauryl peroxide is obtained.

Preparation of graft latex 2 in emulsion A 120 l autoclave is charged with: 60.6 kg of water, 2.60 kg of an aqueous solution containing 10% by weight of sodium tetradecyl sulfonate, 0.053 kg of ammonia, 22 ° Beaum®, 52 kg of vinyl chloride.

The mixture is then heated to 52 ° C under autogenous pressure and this temperature is maintained throughout the work. As soon as the temperature of the mixture is 52 [deg.] C., 0.035 kg of potassium persulphate are added to the mixture, after 15 minutes 4.75 l of an aqueous solution containing 10% of sodium tetradecyl sulfonate 0.5 l / h are added continuously.

After 9 1/2 h at 52 ° C, the unreacted vinyl chloride is evacuated. A latex having a polymer concentration of 40.2% by weight and a particle diameter of 0.12 μm is obtained. There is no initiator in these particles.

14 61706

Polymerization The following are placed in a 120 l autoclave: - 33,2 kg of water, 5,7 kg of latex 1, ie 2,3 kg of polyvinyl chloride containing 34,5 g of lauryl peroxide, 3,5 kg of latex 2, ie 1,4 kg of polyvinyl chloride, 1.5 kg of an aqueous solution containing 10% by weight of sodium dodecylbenzenesulfonate, 55 kg of vinyl chloride.

The reaction mixture is stirred and the stirrer speed is then 50 rpm and at the same time heated to 52 ° C. After 3 h, 2.5 kg of an aqueous solution containing 10% by weight of sodium dodecylbenzenesulfonate are added.

After 18 h of reaction, a drop in pressure is observed. When the pressure has dropped by 2 bar, gas is released from the unreacted vinyl chloride. A latex is obtained with a polymer concentration of 54% by weight and a viscosity of 38 cP.

The weight of the deposits formed in the autoclave is not more than 300 g.

Granulometric analysis of the resulting latex shows that the polymer is composed of two populations with corresponding average particle diameters of 0.20 and 0.98. It is noted that the size of the latex 2 particles has increased, although they do not contain the initiator of the reaction. The small particles represent 29% of the weight of the polymer.

The resulting latex is decomposed, the resulting powder is triturated and a plastisol is prepared by mixing 100 parts by weight of polymer and 40 parts by weight of dioctyl phthalate. The rheological properties of plastisol are measured: on the one hand, using a rotary rheometer of type Brookfield RTV (needle No. 6, 20 rpm, measurement and conditioning at 25 ° 0), the results are shown in Table 1; on the other hand, using a rheometer of the Severs extruder type (conditioning for 2 h at 25 ° C), the results are shown in Table 2.

, ** f • \ f '15 61 706 TABLE 1

Brookfield viscosity

Conditioning at 25 ° C Viscosity _hours_______out j_ 0.5 210 440

The table shows that although plastisol contains only a small amount of plasticizer, its viscosity is low and that it develops slowly over time.

TABLE 2

Severs viscosity

Rate Gradient Viscosity _sec 1 _____'_ off___ 235 308 480 280 820 260 Examining this table, it is surprisingly found that the viscosity of plastisol decreases ^ as the rate gradient increases; which is characteristic of the low pseudoplasticity of plastisol and facilitates its use.

A plastisol consisting of 50 parts by weight of dioctyl phthalate per 100 parts by weight of polyvinyl chloride also behaves pseudoplastically, i. the viscosity decreases with increasing velocity gradient.

For comparison, 3 experiments are performed using a single grafting latex according to the procedure described above.

Experiment A is worked on as above, but using ratios of reactants such that a latex with an analogous concentration is obtained.

The reactor is charged with: 32.4 kg of latex, 6.9 kg of latex 1, i.e. 2.75 kg of polyvinyl chloride, 16 61 706 1.5 kg of 10% aqueous sodium dodecylbenzenesulfonate solution, 55 kg of vinyl chloride.

The reaction is carried out under the same conditions. The pressure drop is noted after 18 h. Once the gas has been discharged, there is a precipitated polymer in the reactor which cannot be recovered by conventional separation methods.

Experiment B is carried out as in Experiment A, but the speed of the stirrer is 30 rpm. The pressure drop is noted after 22 h. A latex is obtained having a polymer concentration of 5.5% by weight and a viscosity of 500 cP. The weight of the deposits in the reactor is 2 kg.

Granulometric analysis of the latex shows that it has only one population with an average particle diameter of 1.05 μm.

Latex degradation is difficult. The resulting product is triturated and two plastisols are prepared. The results are reported in Table 3.

TABLE 3 _PLASTISOLI__ PVC DOP Rheology parts by weight parts by weight 100 40 Mass conversion impossible. A highly swellable, heterogeneous resin is obtained.

100 50 Severs viscosity gradient viscosity sec ^ off 138 520 187 770 255 860

Comparison of Experiments A and B with Example 1 shows the improvement obtained by the process according to the invention, so that latices with a high polymer concentration and a low viscosity are obtained. It also shows that the products obtained by the process give plastisols with a higher flowability towards a smaller amount of plasticizer, which allows the coating to take place more quickly.

17 61 706

Experiment C If the amount of initiator in the graft polymer is increased or the reaction activating system is added to accelerate the reaction in Experiment B at high concentration, thermal unevenness in the reaction mixture results from poor reactor heat transfer coefficient when stirring the viscous reaction mixture; as a result, the reactor temperature can no longer be controlled, the reaction is uneven, so the latex is unusable and the molecular weight of the polymer is not as desired.

Example 2

The grafting latices 1 and 2 of Example 1 are used in the polymerization.

Polymerization ✓ - "The 120 l autoclave is charged with: 28.6 kg of water, 5.7 kg of latex 1 or 2.3 kg of polyvinyl chloride, 3.5 kg of latex 2 or 1.4 kg of polyvinyl chloride, 1.5 kg of an aqueous solution containing 10% by weight of sodium dodecyl -benzenesulfonate, 2.7 g of copper sulfate, 55 kg of vinyl chloride.

The reaction mixture is stirred at 50 rpm while heating at 52 ° C.

As soon as the temperature has risen to 52 ° C, a 0.4 l / h aqueous solution containing 0.68 g / l of ascorbic acid is added continuously.

- After keeping the reaction mixture at 52 ° C for 3 h, 2.5 kg of an aqueous solution of 10% by weight are added. sodium dodecylbenzenesulfonate.

After the reaction has continued for 9 h, a pressure drop is observed. When this is 2 bar, the addition of ascorbic acid is stopped and the unreacted vinyl chloride is vented. The result is a latex with a polymer concentration of 55% by weight. and a viscosity of 40 cP.

The weight of the deposits formed in the reactor is not more than 120 g.

Granulometric analysis of the resulting latex shows that the polymer ie 6170 6 consists of two populations. The other comprises 30% by weight of polymer and the average diameter of the particles is 0.20. The second has a weight of 70 and has an average particle diameter of 1 μm. It is observed that the latex 2 particles are enlarged, even if they do not contain the initiator of the reaction.

The latex is decomposed and the resulting polymer is converted into two plastisols containing 40 and 50 parts by weight of dioctyl phthalate, respectively, per 1 part by weight of polymer.

The rheological properties of the first plastisol are shown in Tables 4 and 5 and the properties of the second plastisol in Table 6.

TABLE 4

Brookfield viscosity

Conditioning at 25 ° C Viscosity one hour away! 0.5 180 24 300 TABLE 5

Severs viscosity

Velocity gradient Viscosity sec * off 215 360 400 350 670 340 This plastisol behaves very slightly pseudoplastically, as indicated by a decrease in viscosity with increasing velocity gradient.

Comparing Tables 2 and 5> i.e., Examples 1 and 2, it is found that the activation of the initiating agent has virtually no rheological properties; it does not affect anything other than the rate of the reaction.

19 Table 6 61 706

Severs viscosity

Speed gradient,

Viscosity sec _______ Off! ___ 90 112 220 100 5 ^ 0 80

Comparative experiment D. Polymerization in emulsion.

Preparation of plexus latex 1 in emulsion.

The 120 l autoclave is charged with: 6 l of water, 0.053 kg of ammonia 22 ° Beaume - 2.6 kg of the grafting latex 2 of Example 1, i.e. 1.150 kg of polyvinyl chloride, 50 kg of vinyl chloride.

The mixture is then heated to 52 ° C under autogenous pressure and this temperature is maintained throughout the work. As soon as the temperature of the mixture is 52 [deg.] C., 0.035 kg of potassium persulphate are added to the mixture, then, after 15 minutes, 0.55 l / h of sodium tetradecyl sulphonate are added continuously. After 9 1/2 hours, the unreacted vinyl chloride is evacuated. The result is a latex with a polymer content of 40.5% by weight and a particle diameter of 0.40 .mu.m.

Polymerization A 120 l autoclave is charged with: 45 kg of water, 0.053 kg of ammonia, 22 ° Eeaume, - 4.10 kg of emulsion latex 1, i.e. 1.67 kg of polyvinyl chloride, - 2.55 kg of latex 2 of Example 1, i.e. 1.02 kg polyvinyl chloride, - 40 kg of vinyl chloride.

The mixture is then heated to 52 ° C under autogenous pressure, and this temperature is maintained throughout the work. As soon as the mixture has reached a temperature of 52 [deg.] C., 0.025 kg of potassium persulphate are added, followed 15 minutes later by a continuous addition of 5 l of 10% by weight of sodium dodecylbenzenesulfonate 0.5 l / h.

After a reaction of 10 h, the unreacted vinyl chloride is vented. A latex with a polymer content of 42% by weight is obtained. The weight of the shells formed in the reactor is 500 g. Granulometric analysis of the resulting latex shows that the polymer consists of two populations. Repeat is 39 weight ?? the polymer and has an average particle diameter of 0.83 μm; another population is 61 weight ?? and its particles have an average diameter of 0.34 μm.

The latex is decomposed and converted to plastisol as in Example 1.

The rheological properties are as follows: TABLE 7

Brookfield viscosity

Conditioning at 25 ° C Viscosity __ hours ___ | __off_ 0.5 1800 24> 2000 TABLE 8

Severs viscosity

Velocity gradient Viscosity _sec ^ ____ off__ 105 2050 160 3100 190 4200

A comparison of Example 2 and Experiment D shows a large particle size difference in the latexes obtained by polymerization in microsuspension and emulsion and consequently a difference in rheological properties in plastisols prepared using polymers of these latexes as starting materials.

Examples 3 ~ 9 Polymerization

All of these examples use a 120 I autoclave charged with: varying amounts of water, 5.7 kg of the latex 1 of Example 1, i.e. 2.3 kg of polyvinyl chloride, varying amounts of latex 2, in each example the average diameters of the particles 21 61706 are different; this difference in the average diameters of the particles is obtained by varying the amount of emulsifier used in the initial preparation of the latex of Example 1 2, 0.55 kg of a 10% by weight aqueous solution of sodium tetradecyl sulfonate, 4 g of copper sulphate, 55 kg of vinyl chloride.

The procedure is the same as in Example 2, except that 3.5 kg of the same sodium tetradecylsulfonate solution is added during the polymerization instead of the sodium dodecylbenzenesulfonate solution.

The varying magnitudes of the reaction and the results obtained are shown in Table 9 ·

Examination of the table shows the importance of the total amount of grafting latices, the relative proportions of the two grafting latices and the diameter of the particles of said latexes in the amount of deposits formed during polymerization, as well as the granulometry of the latexes obtained.

Example 10

Example 2 is repeated, but the amount of water used in the polymerization is 11.7 kg instead of 28.6 kg.

Upon completion of the reaction, the amount of polymer contained in the latex is 67% by weight and its viscosity is 60 cP. The weight of the deposits formed in the autoclave is 240 g.

Of the particles contained in the latex, 29% by weight have an average diameter of 0.19 μm and 71% by weight have an average diameter of 1 μm.

The latex thus obtained is divided into two parts.

The first part is decomposed under normal conditions at low temperature. The obtained powder is triturated and converted into a p-astisol by mixing 40 parts of dioctyl phthalate per 100 parts of powder.

The rheological properties of plastisol, measured as in Example 1, are summarized in Tables 10 and 11.

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Conditioning at 25 ° C Viscosity hours off 0.5 220 24 460 TABLE 11 Severs viscosity

Rate Gradient Viscosity _sec · * · ___ off_ 243 313 500 302 "830 272 This example surprisingly shows that with the process according to the invention it is possible to obtain latices with a very high concentration, a low viscosity and no formation of deposits.

The other half of the latex is decomposed at a higher temperature. The obtained powder has polyvinyl chloride particles with an average diameter of 113 μm and an apparent molecular weight of 0.6 μm. g / ml and a viscosity index of 117 · 100 parts by weight of the polymer thus obtained are mixed with 0.5 parts by weight of calcium stearate, 4 parts by weight of a lead-containing stabilizer and 4 parts by weight of titanium oxide. The mixture thus obtained is then examined with the aid of Brabender extrusion chromatography and Brabender plastography in comparison with the same mixture prepared using polyvinyl chloride obtained by polymerizing the pulp, viscosity index 101.

The results are shown in Table 12.

2 “61706 TABLE 12 BRABBNDER-PLASTOGRAFT BRABENDER-EXTRUSION GRAPHIC mass 600 2,350 1.62 233 2.53 expands

It is found that the polyvinyl chloride obtained by the process of the invention turns into a gel faster, extrudes slightly faster and swells less after coming out of the mouthpiece than polyvinyl chloride prepared by bulk polymerization.

Example 11

The graft latex 1 in the microsuspension is the same as that prepared in Example 1.

Preparation of graft latex 2 in microsuspension.

Work as in Example 1; grafting latex 1 is prepared using 8 kg of 10 wt.% aqueous solution of sodium dodecylbenzenesulfonate instead of 4 kg and 0.04 kg of lauryl peroxide instead of 0.6 kg. Homogenize very finely.

The particles of the obtained latex have an average diameter of 0.12 μm and contain only 0.07% by weight of the reaction initiator.

Polymerization The following is introduced into a 120 l autoclave: 28.6 kg of water, - 5.7 kg of latex 1, i.e. 2.3 kg of polyvinyl chloride, 3.5 kg of latex 2, i.e. 1.4 kg of polyvinyl chloride, which contains only very little initiator a substance corresponding to 0.002% by weight of the monomer in the mixture, 2.7 g of copper sulphate, 1.5 kg of 10% by weight of an aqueous solution of sodium dodecylbenzenesulphinate, -5 .mu.g of vinyl chloride.

The reaction is carried out as in Example 2. The polymer of the obtained latex has a concentration of 54% by weight and a viscosity of 60 cP. The weight of the pellets is about 100 g.

The polymer consists of two populations of particles with corresponding average particle sizes of 0.19 μm and 1 μm, respectively, and in which the proportion of small particles is 29% by weight.

It is noted that the particles of latex 2 are enlarged, although the amount of initiator contained therein is practically equal to zero.

Example 12

Preparation of graft latex 1 in microsuspension

The preparation of the grafting latex 1 of Example 1 is repeated, but the homogenization is performed so that the particle size of the latex is 0.48 μm. The concentration of the polymer is 39.5% by weight and the particles contain 1.5% by weight of lauryl peroxide based on the polymer.

Preparation of graft latex 2 in microsuspension

The preparation of the grafting latex 1 of Example 1 is repeated, but the homogenization is carried out so that the particle size of the latex is 0.1 .mu.m. The concentration of the polymer is 40 # and the particles contain 1.5% by weight of lauryl peroxide based on the polymer.

Polymerization The 120 L reactor is charged with: 31.2 kg of water, 1.5 kg of 10 # aqueous sodium dodecylbenzenesulfonate, 9.9 kg of latex 1, i.e. 3.9 kg of polyvinyl chloride, 6.35 kg of grafting latex 2, i.e. 2 , 5 kg polyvinyl chloride, 55 kg vinyl chloride.

The reaction mixture is stirred and heated to 52 ° C under autogenous pressure and this temperature is maintained throughout the reaction.

After the reaction has continued for 3 h, 2.5 kg of an aqueous solution of 10% by weight of sodium dodecylbenzenesulfonate are added to the mixture. The pressure drop occurs 12 h after the start of the reaction. At 2 bar, the unreacted vinyl chloride is degassed.

26 61 706

The resulting latex has a polymer concentration of 54% by weight. The layers weigh 500 g.

The average diameters of the two particle populations contained in the polymer are 0.18 μm and 0.99 μm and correspond to 29 and 71 wt.

Example 13

Example 8 is repeated, but the polymerization uses: 16.4 kg of water, 52.25 kg of vinyl chloride and 2.75 kg of vinyl acetate.

The resulting latex has a concentration of 58.1% by weight and a viscosity of 40 cP. The layers weigh only 150 g. The polymer consists of 22 weight # particles with an average diameter of 0.22 μm and 78 weight # particles with an average diameter of 1.05 μm.

The latex is broken down; the product obtained is a copolymer containing 3 * 6% by weight of vinyl acetate. The rheological properties of plastisols containing different amounts of dioctyl phthalate are shown in Table 13 · TABLE 13 DOP Brookfield___Severs___ _n Viscosity-Off Rate Viscosity ^ ^ ittl_ 40 280 660 100 700 50 100 220 («O (390 60 30 35 (¾ ° (7 °

It is found that when plastisol contains 40 parts by weight of dioctyl phthalate per 100 parts by weight of vinyl chloride-vinyl acetate copolymer, its viscosity is low; with previous methods, this is impossible.

Example 14 The grafting latex 1 used is the same as in Example 1.

Prepare grafting latex 2 in emulsion 27 6 1 7 0 6

The work is carried out in exactly the same manner as in Example 1. The diameter of the particles obtained is 0.115 μm.

Polymerization Example 2 is repeated.

Upon completion of the reaction, the latex has a concentration of 54.9% by weight and a viscosity of 40 cP. The weight of the deposits in the autoclave is J 50 g.

The latex polymer consists of 69 parts by weight with an average diameter of 0.98 μm and 31 parts by weight of particles with an average diameter of 0.19 μm.

Comparative experiments E and F in emulsion using two emulsion-type grafting latexes.

Preparation of graft latex 1 in emulsion

Work as for the preparation of graft latex in Comparative Experiment D of Example 2.

Preparation of grafting latex 2 in emulsion e) The preparation of grafting latex 2 of Example 1 is repeated, but using 1.04 kg of an aqueous solution containing 10% by weight of sodium tetradecylsulfonate instead of 2.6 kg and without the addition of sodium tetradecylsulfonate during the polymerization. The resulting latex has a particle diameter of 0.031 μm.

f) Work in exactly the same way as in e). The resulting latex has a particle diameter of 0.025 μm.

The next 2 polymerizations are performed, one using latex 2e, the other using latex 2f, in such proportions that the weight ratio of both populations and the diameter of the largest particles of the resulting latex are approximately the same as the latex of Example 14.

The 25-liter autoclave is charged with: 8000 g of deionized water, ok sv:.

28 61 706

Heat with stirring at 52 ° C. As soon as the mixture has reached this temperature, 4 g of ammonium persulphate are added. After 1 h, 2 l of an aqueous solution containing 1.75% by weight of sodium dodecylbenzenesulfonate 0.23 l / h are added continuously.

At a pressure of 5 bar, the unreacted monomer is cooled and vented.

The amounts used in the work and the results of Experiments E and F are summarized in Table 14 compared to Examples 2 and 14.

Examining this table, it can be seen that the small difference in particle diameters in the microsuspension polymerized grafting layers 2 does not cause virtually any differences in the granulometry and theological properties of the products obtained. In contrast, a similar difference in emulsion-polymerized grafting latices 2 leads to considerable differences in the granulometry of the products obtained and thus in the theological properties. In this case, the method cannot be repeated exactly the same.

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30 61 706

Example 15

Preparation of graft latex 1 in microsuspension

The preparation of grafting latex 1 is repeated as in Example 1 and homogenized so that the average diameter of the latex particles is 0.25. The concentration of polymer in the obtained latex is 40% by weight and the particles contain 1.5% by weight of polymeric lauryl peroxide.

Preparation of graft latex 2 in emulsion

Work as in Comparative Experiment D of Example 2 using 0.43 kg instead of 2.6 kg of the grafting latex 2 of Example 1, i.e. 0.190 kg of polyvinyl chloride.

The resulting latex has a polymer concentration of 40% by weight and a particle diameter of 0.7 .mu.m.

Polymerization The following is introduced into a 120 l autoclave: 52 kg of water, 4.95 kg of latex 1, i.e. 2 kg of polyvinyl chloride, 3 * 15 kg of latex 2, i.e. 1.25 kg of polyvinyl chloride, 1.5 kg of an aqueous solution containing 10% by weight. sodium dodecyl benzenesulfonate, 2.7 g of copper sulfate, 50 kg of vinyl chloride.

The polymerization is carried out in the same manner as in Example 2.

A latex with a polymer concentration of 43% by weight is obtained. Granulometric analysis shows that it contains two populations of elementary particles with corresponding average diameters of 0.88 μm and 0.52 μm and representing 10 and 90% by weight of polymer. This confirms the growth of particles in both branches of the graft.

Example 16

Preparation of grafting latex 1 in a micro-suspension The preparation is the same as that of the latex 1 of Example 1.

Preparation of grafting latex 2 in emulsion The preparation of grafting latex 2 of Example 1 is repeated.

31 61706

Prepare grafting latex 3 in emulsion.

The following are placed in a 120 l autoclave: 65 kg of water, 2 kg of an aqueous solution containing 5% by weight of potassium laurate, 0.053 kg of ammonia 22 ° Beaume, 52 kg of vinyl chloride.

The mixture is heated to 52 ° C under autogenous pressure and this temperature is maintained throughout the work. As soon as the temperature of the mixture is 52 ° C, 0.035 kg of potassium persulfate is added. After 9.30 h at 52 ° C, the gas is released from the unreacted vinyl chloride. A latex having a polymer concentration of 0.2% by weight and a particle diameter of 0.2% is obtained. The particles do not contain a reaction initiator.

Polymerization The following is placed in a 120 l autoclave: 33.2 kg of water, 5.7 kg of latex 1, i.e. 2.3 kg of polyvinyl chloride containing 3.5 g of lauryl peroxide, 1.75 kg of latex 2, i.e. 0.7 kg of polyvinyl chloride, 1.75 kg of latex 3, i.e. 0.7 kg of polyvinyl chloride, 1.5 kg of an aqueous solution containing 10% by weight of sodium dodecylbenzene sulfonate, -5.5 kg of vinyl chloride.

The reaction mixture is stirred with a stirrer at 50 rpm and heated at 52 ° C. After 3 h, 2.5 kg of an aqueous solution of 10% by weight of sodium dodecylbenzenesulfonate are added.

After the reaction has continued for 18 h, a drop in pressure is observed. When the pressure has dropped by 2 bar, gas is released from the unreacted vinyl chloride. A latex with a polymer concentration of 5% by weight and a viscosity of 25 cP is obtained.

The layers formed in the autoclave weigh only 300 g.

Granulometric analysis of the resulting latex shows that the polymer is composed of three populations with mean diameters of 0.16 μm, 0.40 μm and 0.97 μm, respectively, and represent 16 61, 20 #, respectively. and 64 # by weight of polymer.

If the latex obtained according to this example is compared, it is found that the viscosities are different at the same concentration.

Example 17 The grafting latex 1 used is the same as in Example 1.

Prepare grafting latex 2 in emulsion

The preparation of the grafting latex 3 of Example 16 is repeated.

Prepare graft latex 3 in emulsion

Work is carried out in the same way as for the preparation of the grafting latex of Comparative Experiment D of Example 2.

Polymerization A 120 l autoclave is charged with: - 33.2 kg of water, 5.7 kg of latex 1, i.e. 2.3 kg of polyvinyl chloride containing 34.5 g of lauryl peroxide, 10.5 kg of latex 2, i.e. 4.2 kg of polyvinyl chloride, 10.5 kg of latex 3, i.e. 4.2 kg of polyvinyl chloride, 1.5 kg of an aqueous solution containing 10% by weight of sodium dodecyl benzenesulfonate, 55 kg of vinyl chloride.

Polymerization as in Example 16 gives a latex having a polymer concentration of 53% by weight and a viscosity of 45 cP.

The weight of the deposits formed in the autoclave is not more than 720 g.

Granulometric analysis shows that the latex contains three populations of elementary particles with average diameters of 0.26 μm, 0.54 μm and 0.92 μm, respectively, and represent 22, 32 and 46% by weight of polymer.

Example 18

The oxactus latexes J and 2 of Example 16 are used for polymerization.

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33 61 706

Prepare graft latex 3 in emulsion

The preparation of the grafting latex 2 of Example 1 is repeated, but using 1.04 kg of an aqueous solution containing 10% by weight of sodium tetradecyl sulfonate instead of 2.6 kg, and no sodium tetradecyl sulfonate is added during the polymerization. The resulting latex has a particle diameter of 0.0 to 31.

Polymerization

Work under the same conditions as in Example 16. A latex having a viscosity of 22 cP and containing three populations representing 13, 22 and 65% by weight of polymer and having average particle diameters of 0.067 μm, 0.19 μm and 0, respectively, is obtained. 97 / m.

Example 19

Preparation of grafting latex 1 in microsuspension The preparation of grafting latex 1 of Example 1 is repeated.

To prepare grafting latex 2 in emulsion, 25 kg of water, 0.75 kg of grafting latex 3 of Example 18, i.e. 0.3 kg of polyvinyl chloride, are placed in a 25 l autoclave.

Heat with stirring at 75 ° C and maintain this temperature throughout the work. As soon as the temperature of the mixture is 75 ° C, 12 g of potassium persulfate dissolved in 100 g of water are added, then 6 kg of butyl acrylate and 1 liter of an aqueous solution containing 30 g of sodium pyrophosphate and 60 g of sodium dodecylbenzenesulfonate are added continuously for 3 h. The reaction is stopped after 8 h; a latex having a polymer concentration of 33% by weight and an average particle diameter of 0.09 μm is obtained.

Polymerization

The procedure is as in Example 1, but using 4.25 kg of the above latex 2, i.e. 1.4 kg of polymer.

The resulting latex has a concentration of 52% by weight and a viscosity of 40 cP.

Claims (10)

A process for preparing copolymers comprising polyvinyl chloride or at least 50% by weight of vinyl chloride and at least one monomer copolymerizable with vinyl chloride, which process comprises polymerizing the corresponding monomers in a microsuspension in the presence of a grafting agent in the form of a vinyl polymer , consisting of vinyl chloride homopolymers, vinyl chloride copolymers having one copolymerizable monomer and homopolymers and copolymers of copolymerizable monomers, a grafting agent that the polymerization is carried out in the presence of one or more other grafting agents in the form of dispersions of vinyl polymer particles in which the particle sizes are e both to each other and to the first grafting agent, the total amount of grafting agents used being such that the amount of polymers they contain is from 1 to 50% by weight of the sum of polymerizable vinyl chloride and grafting polymers, the ratio of first grafting polymer to other grafting polymers is 95 / 5-5 / 95 and grafting polymers. and the concentration of vinyl chloride or a mixture of vinyl chloride and copolymerizable monomer, taking into account the water content of the grafting agents, is 20 to 80% by weight of the reaction mixture. A method according to claim 1, characterized in that the particles of the other or other grafting agents contain at least one initiator. Process according to Claim 1, characterized in that the average particle diameter of the polymer of the other or other grafting agents is 0.02 to 1.5 μm. . Process according to Claim 1, characterized in that the other or other grafting agents are prepared by polymerizing in a microsuspension in the presence of an organololuble initiator. Process according to Claim 1, characterized in that the other or other grafting agents are prepared by polymerizing in an emulsion in the presence of a water-soluble initiator. Process according to Claim 1, characterized in that an anionic emulsifier is added before and / or during the polymerization, optionally together with a nonionic emulsifier. Process according to Claim 1, characterized in that the polymerization rate is accelerated by activating the reaction initiator contained in the grafting particles with an organoluble metal complex formed in situ. 8. A latex containing polyvinyl chloride or at least 50% by weight of vinyl chloride and at least one monomer copolymerizable with vinyl chloride, prepared by polymerizing in a microsuspension in the presence of at least two grafting agents in the form of dispersions of vinyl polymer particles of different particle sizes, contains at least two populations of particles with different mean diameters. Latex according to Claim 8, characterized in that it contains two populations of particles with average diameters of 0.4 to 2.5 μm and 0.08 to 1 μm, respectively, and a diameter ratio of 1 to 20 and a weight ratio of 0, 1-10. Latex according to Claim 8, characterized in that it contains three populations of particles with average diameters of 0.4 to 2.5 μm, 0.15 to 1 μm and 0.05 to 0 μm, respectively. um, and 36 61 706 larger proportions of larger particles / medium particles and medium particles / very small particles are either the same or different from 1 to 20, and weight ratios of larger particles / medium particles and medium particles / very small particles are either the same or different , 1-20. Latex according to Claim 8, characterized in that it has a polymer concentration of 20 to 75% by weight.