DE2342511A1 - PROCESS FOR POLYMERIZING AETHYLENIC UNSATABLED COMPOUNDS - Google Patents

Description

Patent attorney

6500 Giessen / Lahn August 22; 1973

Ludwigstrasse 67 H / He (584)

PPG Industries, Inc., Pittsburgh. Pa., U.S.A.

Process for the polymerisation of ethylenically unsaturated compounds

Priority: August 28, 1972 USA Serial No. 284 025

This invention relates to a process for polymerizing ethylenically unsaturated compounds which generate free radicals Initiators.

The polymerization of ethylenically unsaturated compounds, their polymerization by free radical initiators can be stimulated, is described in numerous literature sources and is used widely in technology. Examples of such ethylenically unsaturated compounds are vinyl monomers, such as vinyl chloride; Typical free radical initiators are the organic peroxides. Among the organic peroxides used as initiators have already been proposed for the polymerization of such monomeric compounds include diacyl peroxides, such as dilauroyl peroxide, dibenzoyl peroxide, diisobutyryl peroxide; Dialkyl peroxydicarbonates, such as diisopropyl peroxydicarbonate, di-n-propyl peroxydicarbonate, di-sec-butyl peroxydicarbonate, Dicyclohexyl peroxydicarbonate, di-4-6 ~ butylcyclohexyl peroxydicarbonate and di-2-ethylhexyl peroxydicarbonate; and t-butyiperoxy ester, vxe t-butyl peroxypivalate and t-butyl peroxyneodecancate.

Although the commercially available organic peroxides are widely used as polymerization initiators, however, they have only a limited effectiveness because their rate of decomposition is at a certain temperature has a certain value and the temperature at which the

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Polymerization of the monomer is carried out, adversely affecting the properties of the resulting polymeric product. Therefore, for best results, the rate of decomposition of the initiator should be at the polymerization temperature be such that the polymerization can be carried out at the desired rate. For this In the industry, initiators are often preferred, which have a remarkable reactivity at relative reason low temperatures, e.g. below 50 C, so that high polymerization rates at such temperatures can be achieved. It is of course clear from the outset that organic peroxides are volatile Are compounds and that their volatility increases with their reactivity. Very reactive organic However, peroxides have the disadvantage of decomposing, often very quickly, at room temperature. When using such The risk of accidents is therefore great for peroxides.

Organic peroxides are often explosive at temperatures above room temperature. In addition, numerous organic peroxides have the disadvantage that they are very sensitive to impact are. For example, diacetyl peroxide, dipropionyl peroxide and diisobutyryl peroxide are known to explode when heated decompose. These compounds are also sensitive to impact, which is due to the fact that they are stabilized Form to be placed on the market. Dipivaloyl peroxide is likely despite its high reactivity therefore not commercially available because it is very volatile.

The reactivity of the diacyl peroxides depends in part on the nature of the hydrocarbon radicals attached to the Carbpnyl carbon atoms are bonded. This is how it works, for example Lauroyl peroxide, which contains a long hydrocarbon residue, relatively slow at low temperatures. In order to obtain a short polymerization time, therefore, must be long Quantities of this initiator are used or the polymer

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rization must be carried out at higher temperatures. Both alternatives are often undesirable because of the use a higher concentration of the initiator often adversely affects the thermal stability of the polymer obtained, as a result, when heated to higher temperatures, the polymer is more likely to be discolored. The usage of higher polymerization temperatures leads to a lowering of the molecular weight of the polymer, thereby creating a series caused by undesirable changes in the physical properties of the polymer.

The reactive diacyl peroxides, such as diisobutyryl peroxide, act faster at relatively low temperatures, but can only be manufactured, transported and used with considerable risks. Cooling devices are often required for their transport and storage. In addition, the reactive diacyl peroxides tend to exhaust themselves very quickly X) Qi the usual temperature of polymerization, that is to say that they decompose completely before the polymerization reaction has progressed to a high degree of conversion of the monomer to the polymer. By using larger amounts of the reactive initiator it is possible to partially compensate for premature consumption, but this solution is undesirable because the polymerization reaction proceeds too quickly and the heat released in the reactor cannot be dissipated to the desired extent. As a result, continuous polymerization, combined with higher temperatures, can occur, as a result of which the physical properties of the polymer change in an undesirable manner because of the aforementioned lowering of the molecular weight.

Dialkyl peroxydicarbonates, such as diisopropyl peroxydicarbonate, have proven themselves as initiators for the polymerization of ethylenically unsaturated monomers, such as vinyl chloride, in common Polymerization temperatures, i.e. 45 to 80 ° C, proved suitable. Although the peroxydicarbonates in general

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Generally useful polymerization rates give, there is a desire to further shorten the Polymerization time.

Most of the diacyl peroxides used in engineering today have a satisfactory rate of decomposition at temperatures of 50 to 100 ° C. In contrast, there is a Lack of economically viable and safe initiators for free radical polymerization at temperatures below 50 ° C. This deficiency is very pronounced because the polymers produced at these temperatures have different properties than the polymers produced at temperatures above 50 ° C. In addition, the combination of such Initiators used with the usual initiators to increase the performance of existing polymerization systems can be.

It has now been found that the accident hazards and problems associated with the use of more reactive radical-forming initiators, ie initiators that are able to have a sufficient concentration of free radicals to initiate and propagate the polymerization at relatively low temperatures, ie below 50 ° C, can be avoided if an acid anhydride in combination with an organic peroxy acid (peracid) is used as the initiator.

To carry out the polymerization, the acid anhydride and the organic peracid are introduced separately into the polymerization vessel and into the polymerization medium. The presence of the peracid in combination with the acid anhydride leads to the polymerization of the ethylenically unsaturated compound which is located in the polymerization vessel.

It has also been found that the peracid and the acid anhydride advantageously also in combination with one another organic initiator that forms free radicals, such as lauroyl

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peroxide, a dialkyl peroxydicarbonate or azobisisobutyro nitrile can be used. It will be a smooth one and continuous polymerization with shorter polymerization times compared to the sole use of such organic initiators achieved.

The process according to the invention can be carried out with any ethylenically unsaturated compounds, i.e. compounds which is an ethylene radical H H or a vinyl radical

p = CC), as far as these compounds of the polymerization accessible by free radicals. Examples of such compounds are: aryl-substituted olefins, such as styrene, alpha-chlorostyrene and the like; Acrylic acids and alpha-substituted acrylic acids and their derivatives, such as methacrylic acid, C-, - C ^ alkyl esters, nitriles and amides of such acids as acrylonitrile, alpha-methacrylonitrile, Methyl acrylate, ethyl acrylate, methyl methacrylate, methacrylamide, Acrylamide and the like; Vinyl esters, vinyl ethers, vinyl ketones and heterocyclic halogen-containing vinyl and vinylidene compounds, such as vinyl chloride, vinylidene chloride, vinyl acetate, vinyl propionate, vinyl butyrate, vinyl fluoride, vinylidene fluoride, chlorofluoroethylene, tetrafluoroethylene, 1,1-difluoro-2,2-dichloroethylene, Perfluoropropylene, 3,3,3-trifluoropropylene, 3,3,3-trichloropropylene, 2-chloropropylene and the like; and unsaturated Polyester.

Unsaturated polyesters are known and typically are produced by reacting dibasic acids or their anhydrides and polyhydric alcohols, whereby one of these components is unsaturated. In general, the dicarboxylic acid or its anhydride is unsaturated. As a dicarboxylic acid usually maleic acid, maleic anhydride, fumaric acid or itaconic acid is used. Often used alongside the unsaturated acids also used saturated acids or their anhydrides. Examples of such acids are chlorenedic acid and its anhydride, succinic acid and its anhydride,

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Sebacic acid, phthalic acid and their anhydride, isophthalic acid, terephthalic acid and adipic acid.

The polyhydric alcohols used for the production of the unsaturated polyester are usually dihydric, however, they can also contain three or more hydroxyl groups. Examples of such alcohols are saturated alcohols, such as ethylene glycol, propylene glycol, diethylene glycol, Triethylene glycol, neopentyl glycol, tetraethylene glycol, Butylene glycol, dipropylene glycol, glycerine, trimethylol ethane, Trimethylolpropane, pentaerythritol and the like. The most commonly used unsaturated alcohol is allyl alcohol.

The preparation of the unsaturated polyesters is described, for example, in US Pat. No. 3,390,135. Further reaction of the unsaturated polyester with a vinyl monomer such as vinyl acetate, styrene or methyl methacrylate gives crosslinked, three-dimensional resins. The copolymerization of the unsaturated polyester with the vinyl monomer to produce the crosslinked polyester resin is a free radical polymerization. . Initiators triggered reaction which is essentially vinyl type polymerization. The catalyst combinations according to the present invention can consequently be used for the interpolymerization of unsaturated polyesters with vinyl compounds.

The method of the invention thus provides an effective and safe source for the generation of free Free radicals are available for polymerization. Other applications of this process are its use as a vulcanization or hardeners for elastomers, e.g. natural and synthetic rubbers, polyurethanes and adhesives, and as crosslinking agents for polyolefins such as polyethylene and ethylene-containing copolymers.

The method according to the invention is very special for Homo- and copolymerization of vinyl chloride suitable. as

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-T-

Comonomers can include, for example, vinyl bromide, vinylidene chloride, vinyl acetate, methyl acrylate; Methyl methacrylate and mixtures of two or more of these monomers can be used. If vinyl chloride is copolymerized with one or more other monomers, vinyl chloride is generally used in amounts of more than 50 mol / 6, for example in amounts of 75 to 95% vinyl chloride and from 25 to 5% of the comonomer or comonomers. With regard to their structure, the copolymers can be any copolymers, such as graft copolymers, random copolymers, alternating copolymers and block copolymers. The exact structure of the polymeric product is more a function of the particular polymerization process used and less of the initiator used.

The type of polymerization product obtained from said polymerizable materials, e.g. vinyl chloride, depends to a large extent on the temperature at which the polymerization is carried out. For example, polyvinyl chloride, which was produced at polymerization temperatures in the range of 40-65 ° C, the most desired Properties for most of its commercial uses.

As already stated, dialkyl peroxydicarbonates, such as diisopropyl peroxydicarbonate, are initiators that operate at temperatures from 45 to 80 ° C, e.g. 45 to 55 ° C, are effective. Although the peroxydicarbonates are generally sufficient Polymerization rates result, there is a desire to further reduce the polymerization time. this can be achieved by shortening the warm-up period in the polymerization cycle. With a typical Vinyl chloride polymerization is a batch process the contents of the polymerization vessel will normally be at room temperature or lower at the start of the cycle Temperature. The contents of the reactor are heated or allowed to be heated to temperatures close to the

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desired polymerization temperature. As soon as the polymerization has started, heat is released from the vessel removed by indirect heat exchange means to bring the polymerization temperature to the desired level keep. Most polymerization vessels use tap water as a coolant to remove the excess Heat of polymerization used. As a result, however, the cooling speed - i.e. the speed with which Heat can be removed from the reactor, considerably limited. This limitation, in turn, has a limiting effect on the type of initiator that can be used in such vessels because only those initiators can be used that produce free radicals fairly evenly in the desired Generate temperature range.

The use of low temperature initiators, i.e. Initiators that are effective below 50 ° C, e.g. at 20-30 ° C, encounter difficulties. Because such Initiators are supposed to be unstable at room temperature, it is difficult to manufacture, transport and store them and to be used in large-scale polymerization. If such initiators are actually transported are to be, this is done in dilute solution, with the addition of the initiators at the point of manufacture, during be refrigerated during transport and storage. In addition, those can be effective at low temperatures Initiators, such as diisobutyryl peroxide, cause difficulties in the polymerization reaction because they move too quickly decompose and thereby accelerate the reaction too much and generate too much heat. It can lead to an overshoot the cooling capacity of the reactor, as a result of which the polymerization temperature exceeds the desired level, so that polymers with unsatisfactory properties arise. It can also be used at low temperatures effective initiators are exhausted early when higher polymerization temperatures are reached, whereby a significantly lower conversion of the monomer is achieved

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which is usually 80 - 92% in batch operation.

It is therefore surprising that the combined use of one or more organic peroxy acids (peracids) with one or more acid anhydrides to a smooth and controlled polymerization of ethylenic leads to unsaturated compounds. By regulating the amount of the, peracid and the anhydride, the polymerization can take place at a relatively low temperature, i.e. at 20 to 30 ° C, initiated and up to a high conversion of the monomer, i.e. 80 to 92% conversion. For this process is particularly useful to the polymerization in Temperature range of 25 - 50 ° C, preferably 30 - 40 ° C, to be carried out.

The acid anhydrides suitable for the invention are anhydrides of organic acids, in particular aliphatic or aromatic carboxylic acids, preferably saturated monocarboxylic acids. Preferred acid anhydrides can be expressed by the formula _Q q

I! It

R ₁ -COCR ₂

represent in which R, and R _{2 are} independently alkyl, aryl or cycloalkyl radicals. The alkyl radicals generally contain 1 to 20 carbon atoms, preferably 1 to 12 carbon atoms. The aryl and cycloalkyl radicals usually contain 6 to 10 carbon atoms. R ₁ and R ₂ can be the same or different. In most cases, R- and Rp are the same. The alkyl radicals can be straight-chain or branched and the alkyl, aryl and cycloalkyl radicals can also contain substituents which do not negatively affect the polymerization reaction or the product formed, for example alkoxy, halogen, such as chlorine, bromine and fluorine, hydroxyl, amido, cyano, nitroso , Nitro and the like. Remnants. Examples of such acid anhydrides are: isetic anhydride, propionic anhydride, butyric anhydride, isobutyric anhydride, pivalic

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acid anhydride, valeric anihydride, isovaleric anihydride, 2-methylbutyric anhydride, 2-ethylbutyric anhydride, Caproic anhydride, capric anhydride, isocaproic anhydride, n-heptanoic anhydride, nonanoic anhydride, Decanoic anhydride, neodecanoic anhydride, undecanoic anhydride, Ne ohept anhydride, lauric anhydride, Tridecanoic anhydride, 2-ethylhexanoic anhydride, Acetic acid propionic anhydride, acetic acid isobutyric anhydride, myristic anhydride, palmitic anhydride, Stearic anhydride, phenylacetic anhydride, cyclohexanecarboxylic anhydride, 3-methylcyclopentanecarboxylic anhydride, beta-methoxypropionic anhydride, alpha-ethoxybutyric anhydride, Benzoic anhydride, o-, m- and p-toluic anhydride, Trimethylbenzoic anhydride, o-, m- and p-chlorobenzoic anhydride, o-, m- and p-bromobenzoic anhydride, o-, m- and p-nitrobenzoic anhydride, o- and p-hydroxybenzoic anhydride, o-, m- and p-aminobenzoic anhydride and o-, m- and p-methoxybenzoic anhydride.

In combination with such acid anhydrides, organic peroxyacids (peracids) are used in the invention. The preferred peracids are saturated aliphatic or aromatic percarboxylic acids. Such peracids can be expressed by the formula _Q

Il

R 1 -C-O-O-H

represent, in the FU an aliphatic radical with in particular 1 to 20 carbon atoms or an aromatic radical with in particular 6 to 10 carbon atoms is * preferred the alkyl radical contains 1 to 12 carbon atoms. The aliphatic The remainder can be straight-chain or branched. Both the aliphatic and the aromatic radical can have substituents which do not adversely affect the polymerization reaction and the polymeric product. Such remnants are alkoxy, halogen such as chlorine, bromine or fluorine, hydroxyl, amido, cyano, nitroso, nitro and the like.

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Examples of suitable peracids are: peracetic acid, permonochloroacetic acid, Trifluoroperacetic acid, perdichloroacetic acid, pertrichloroacetic acid, perpropionic acid, permonochloropropionic acid, Perdichloropropionic acid, "perbromoacetic acid, perbromopropionic acid, per-alpha-chloro-lauric acid, per-alpha, alpha-dichloro-lauric acid, per-12-hydroxystearic acid, per-alpha-bromocapric acid, Per-alpha-bromostearic acid, perglycolic acid, Peroxy lactic acid, perpyruvic acid, 3-chloroperbenzoic acid, m-bromobenzoic acid, pentafluoroperbenzoic acid, p-tert-butyl perbonzoic acid, perisopropionic acid, per-n-butyric acid, Perisobutyric acid, pervaleric acid, perpivalic acid, Perisovaleric acid, percaproic acid, percaprylic acid, Pernonanoic acid, perdecanoic acid, perneodecanoic acid, perheptanoic acid, Perundecanoic acid, perlauric acid, pertridecanoic acid, permyristic acid, perpentadecanoic acid, perpalmitic acid, Perheptadecanoic acid, perstearic acid, pernonadecanoic acid, pereicosanoic acid, per (alpha-ethyldecanoic) acid, per- (alpha-ethyldodecanoic) acid, Per (alpha-phenyldodecanoic) acid, Phenyl peracetic acid, peroxyfuranic acid, cyclohexane percarboxylic acid, Perbenzoic acid, 2-, 3- and 4-nitroperbenzoic acid, 2-chloroperbenzoic acid, 4-chloroperbenzoic acid, 2,4- and 3,4-dichloroperbenzoic acid, p-fluoroperbenzoic acid, 2-methylperbenzoic acid, p-isopropyl perbenzoic acid, 4-methoxy perbenzoic acid, 4-cyanobenzoic acid, o- and m-aminoperbenzoic acid, o- and p-hydroxyperbenzoic acid, o-bromobenzoic acid, 2-methylperbutyric acid, 2-ethyl perbutyric acid and perphthalic acid. ·

Acid anhydrides are generally produced in industry by heating the corresponding carboxylic acids with acetic anhydride and distilling off the acetic acid. This procedure is particularly useful when the radicals R- and R _{2 are the} same. Another method of making acid anhydrides is by condensing an acid chloride with the sodium salt of an acid. This process can be used to prepare anhydrides in which Rj ^ and Rg are the same or different.

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Numerous processes are known for the production of peroxyacids. The lower peroxycarboxylic acids (up to C ^) are generally produced by the acid-catalyzed reaction of the starting carboxylic acid with 30 to 989% hydrogen peroxide. Sulfuric acid or ion exchange sulfonic acids with a good effect are generally used as catalysts. For water-insoluble aliphatic carboxylic acids with up to 16 or 18 carbon atoms, concentrated sulfuric acid is both a solvent and a reaction medium. For peroxyacids containing 6 to 16 carbon atoms, the yields are usually high and sometimes even quantitative when an appropriate excess of 50 to 65% hydrogen peroxide is used. The C- ^ g and longer-chain aliphatic carboxylic acids are too insoluble in sulfuric acid, but methanesulfonic acid can be used instead of sulfuric acid. With methanesulfonic acid as solvent, substituted aliphatic or aromatic peroxy acids can also be produced. In addition, peroxycarboxylic acids have also been produced by reacting carboxylic acid chlorides or anhydrides with hydrogen peroxide or sodium peroxide. Another process for the production of peroxycarboxylic acids consists in the controlled autoxidation of aldehydes initiated by free radicals in the liquid phase. Details of these processes can be found in the work ^M Organic Peroxides ", Volume I, pages 313-433 by Daniel Swern, Wiley-Interscience, New York, USA (1970).

The amount used in the method of the invention of acid anhydride can vary within wide limits and depends on the particular monomer used and the Polymerization temperature from. As a rule, however, about 0.001 to about 3% by weight of acid anhydride, based on the total amount of the monomer to be polymerized. When polymerizing vinyl chloride, the amount is of the acid anhydride preferably at about 0.01 to about 1% by weight.

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The amount of peracid used depends on the amount of anhydride away. As a rule, it is preferred to use the peracid and the anhydride in equimolar amounts. However, it can also less or more than the molar equivalent amount on peracid, e.g. a molar ratio of anhydride to peracid of about 0.1: 1 to about 5: 1 can be used will. However, the molar ratio of these openings is preferably 1: 1.

The special mechanism by which the acid anhydride and the peracid cause the polymerization of the monomeric compounds is not known with certainty, but it is believed that at least a portion of the anhydride will react with the Peracid combined to form the corresponding diacyl peroxide. The diacyl peroxide in turn decomposes Formation of free radicals which initiate the polymerization of the monomer. From the available Experimental material shows that the formation of the diacyl peroxide occurs simultaneously with the polymerization reaction he follows. By properly selecting the acid anhydride and peracid it is possible to have a variety of one or more To generate diacyl peroxides in the polymerization medium, these diacyl peroxides symmetrically or asymmetrically could be. Since the reactivity of the diacyl peroxides depends in part on the nature of the alkyl substituents, the surrounding the peroxy group, it is therefore possible to initiate the polymerization with a wide variety of diacyl peroxides to be carried out without the dangers associated with the use of the diacyl peroxides itself are.

By using more than one anhydride and / or more than one peracid, several different ones can be used at the same time Generate diacyl peroxides in the same polymerization medium and thereby the polymerization in the presence of diacyl peroxides with different reactivities. For example, you can use a mixture of vinegar

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acid * and isobutyric anhydrides in combination with peracetic acid and / or perisobutyric acid to theoretically form diacetyl peroxide, acetylisobutyryl peroxide and diisobutyric acid peroxide. The method according to the invention therefore enables the use of initiators which are very reactive at low temperatures without the dangers arising with the use of such preformed peroxides, since the anhydrides and peracids used as starting materials are relatively safe to manufacture, transport, and store and are to be handled.

It has also been found that the addition of an alkaline buffering agent to the polymerization medium increases the effectiveness of the acid anhydride and peracid. Suitable alkaline agents that can be used for this purpose are alkali metal carbonates and bicarbonates, such as sodium and potassium carbonate and bicarbonate, furthermore calcium carbonate and bicarbonate, as well as sodium hydroxide, sodium acetate, borax, potassium tartrate, sodium citrate, trisodium phosphate, sodium pyrophosphate, ammonium hydroxide and alkaline-reacting surfactants (Triton). The amount of such buffering agent is not critical and is generally from 100 to 1000% by weight, based on the weight of the acid used. The amount of the buffering agent can also be based on the monomeric starting materials and is then generally about 0.01 to about 10 % by weight, preferably 0.5 to about 1.5% by weight, based on the weight of the or of the monomers. The addition of the buffering agent serves to keep the pH of the reaction mixture at 6 to 12, preferably 8 to 9.

The diacyl peroxides believed to be formed "in situ" in the polymerization medium can be by the general formula

0 0

Il Il

RC-OO-CR ₃
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in which R, R-, or Rp comes from the acid anhydride and R from the peroxycarboxylic acid. R- ,, R ₂ and R, sizid have already been defined. Typical examples are: diacetyl, dipropiohyl, diisobutyryl, dibutyryl, acetylisobutyryl, acetylbutyryl, acetylvaleryl, acetylpropionyl, acetylpivalyl, acetylbenzoyl and acetyl-2-methylbutyryl peroxide.

The method according to the invention is particularly suitable for the polymerization of the monomeric materials in aqueous Medium. In a typical suspension polymerization, the polymerization vessel is filled with water, the suspending agent, Chain terminators, the acid anhydride, the peroxycarboxylic acid and the buffering agent are added. That polymerizable monomers are then added and the reaction vessel will be closed.

Demineralized water is mostly used as water the amount of water depends on the amount of monomeric material introduced. Usually are dilution ratios from 2: 1 to 40: 1 is customary, with dilution ratios of 3: 1 to about 20: 1 being preferred. It is It is surprising that at such dilution ratios the acid anhydride and the peracid are usually used Quantities of initiator appear to react "in situ" with one another to form a diacyl peroxide. This is therefore particularly unexpected as the acid anhydride and peracid also hydrolyze in water. It was therefore to be assumed that with these dilutions the competing hydrolysis reactions of the acid anhydride and the peracid with would proceed at such a rate that little or no diacyl peroxide is produced and by no means so much that the polymerization reaction can thereby be stimulated and maintained. For example, if you look at similar Try using acid chlorides instead of acid anhydrides no polymerization occurs.

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The temperature at which the polymerization is carried out, can vary within a wide range. The temperature used in the individual case depends on the specific monomers and the desired properties of the polymer. In general, such polymerizations are carried out at temperatures from about 0 to about 95 ° C. For the gay or copolymerization of vinyl chloride, e.g., vinyl acetate or vinylidene chloride, are the preferred polymerization temperatures at about 20 to about 70 ° C.

When selecting the amounts of acid anhydride and peracid, the procedure is based on the assumption that it is theoretical a certain amount of diacyl peroxide is formed in the polymerization vessel. It is also assumed that the entire Acid anhydride reacts with an equimolar amount of peracid. With regard to the competing hydrolysis reactions it is believed that not all of the acid anhydride and all of the pergic acid form the corresponding dialyl peroxide form. For this reason, the theoretically formed diacyl peroxide varies between about 0.01 to about 1.0% by weight, based on the total weight of the monomers. In general, that amount of diacyl peroxide, that is required to start and maintain the polymerization is referred to as the initiating amount.

When carrying out the process according to the invention, the acid anhydride and the peracid are separated and in any Sequence in the polymerization vessel, i.e. in the medium in which the reaction takes place, introduced. As a result, the acid anhydride and the peracid can be used separately, but at the same time or first the acid anhydride and then introduce the peracid or vice versa. Furthermore, you can first a component of the initiator system in bring in the polymerization vessel, then charge the vessel with the monomer (s) and then the other Add components of the initiator system. The most recently added component of the initiator system can also be

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be introduced early with the monomer. The manner in which the acid anhydride and the peracid are added to the polymerization medium is therefore not critical. The initiator components can consequently also in one portion or in individual portions continuously or intermittently, diluted with a suitable solvent or diluent or introduced into the reaction medium in undiluted form! «. Under a suitable solvent or Diluent is to be understood as a material that does not impair the stability of the acid anhydride and the peracid and also has no adverse effect on the polymerization and the polymeric product. If here the When speaking of a polymerization vessel, it is not intended to be restricted to specific polymerization vessels. The initiator system can be used except for the typical polymerization vessels also use for closed or open forms and the like.

As already stated, polymerizations in an aqueous polymerization medium, were added to the emulsifier or suspending agent. Such means serve to make the polymer particles to disperse or suspend in the aqueous medium. The suspension product usually obtained is one Latex or a suspension that is about 35% or more contains dispersed solids. The initiator system according to the invention can be used both in the emulsion and apply the suspension polymerization and also at solution and bulk polymerization. For the sake of brevity, both types of polymerization are discussed here referred to as suspension polymerization in an aqueous medium.

The suspending agent used in the suspension polymerization is not essential to the invention. The suspending agent can be nonionic, cationic or anionic, or a mixture of such suspending agents. Examples of anionic Suspending agents are sodium salts of sulfated ones

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- IS -

or sulfonated hydrocarbons and fatty acids, such as Dioctyl sodium sulfosuccinate, sodium dodecylbenzenesulfonate, Sodium decylbenzenesulfonate, ammonium laurylbenzenesulfonate, Potassium stearylbenzenesulfate, potassium myristylnaphthalene sulfonate, Potassium oleate, ammonium laurate, sodium laurate; sulfonated Diesel oil and sodium lauryl sulfate, sodium alkyl naphthalene sulfonate, Sodium salt of sulfated alkylphenoxypolyoxyethylene, ammonium dodecylphenoxypolyoxyethylene ethyl sulfate, Nonylphenoxyacetic acid, sulfated cresylic acid, disodium N-octadecyl sulfosuccinamate, Tetrasodium N- (1,2-dicarboxyethyl) -N-octadecylsulfosuccinamate, Diamyl ester of sodium sulfosuccinic acid, dihexyl ester of sodium sulf whether seriously monoic acid, bis (tridecyl) ester of sodium sulfosuccinic acid, Dioctyl sodium sulfosuccinate, sodium dodecyl diphenyl oxide disulfonate, Benzene potassium sulfonate, sodium salt of sulfonated naphthalene-formaldehyde condensate, sodium salt of polyethoxyalkylphenolsulfonate, sodium oleylmethyl tartrate and triethanolamine salt of polyethoxyalkylphenol sulfonate and complex organic phosphates. Examples of Cationic suspending agents are quaternary ammonium compounds, such as stearamidopropyl-dimethyl-beta-hydroxyethylammonium nitrate, Cetylpyridinium chloride and cetyltrimethylammonium bromide.

Examples of nonionic suspending agents are high molecular weight Polymers of propylene oxide and / or ethylene oxide, nonylphenoxypoly (ethyleneoxy) ethanols, polyoxyethylated Fatty alcohols, alkylaryl polyether alcohols, such as laurylphenyl polyether ethanol, Alkanol, fatty amine condensates such as triethanolamine, Coconut fatty acid ethanolamide, lauric acid propanolamide, Fatty alcohol polyglycol ether, myristylphenol polyglycol ether, Polyoxyethylene monooleate, polyoxyethylene sorbitol septaoleate, Polyoxyethylene sorbitoleate or laurate, polyoxyethylene acetyl alcohol, polyoxyethylene stearate, glycol amido stearate and other polyoxyethylene alkanols and alkylphenols containing 2 to 40 moles of ethylene oxide per mole of alkanol or Contain alkylphenol.

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Anionic suspending agents are preferred because they are more effective in stabilizing the resulting polymer latex are. The most suitable one can be found for the individual case Suspending agent depending on the process conditions and the starting materials by simple experiments easy to determine. Other suspending agents that can be used in the invention are protective colloids such as Gelatin * methyl cellulose, tragacanth and whole or partially hydrolyzed polyvinyl acetates. Furthermore, as Suspending agents, hydroxylated phosphatides or complex soybean oils (hydroxyl lecithins) are also suitable.

The amount of suspending agent used usually varies between 0.3 and 5%, based on the weight of the polymerizable Monomers. However, larger or smaller quantities can also be used. The suspension of the monomer in the aqueous medium can be done by any suitable means, such as by stirring or agitating the starting materials in the reaction vessel.

In a further embodiment of the invention, at least another organic initiator which forms free radicals and which is free under the polymerization conditions Free radicals are introduced into the polymerization medium in addition to the acid anhydride and peracid. Preferred a free radical initiator is used, which is involved in the formation of free radicals in the desired Polymerization temperature has good efficiency. Such a temperature is typically higher than that in which the diacyl peroxide, which is theoretically formed from the acid anhydride and the peracid, has a high efficiency Has. For example, the use of isobutyric anhydride and acetic acid theoretically leads to the formation of acetylisobutyryl peroxide, which has a high efficiency in the formation of free radicals at a temperature of 30 to 40 ° C. In combination with this, an organic peroxy compound which has high efficiency in the

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-. 20 -

Formation of free radicals at around 45 to 55 ° C, e.g. a dialkyl peroxydicarbonate such as diisopropyl peroxydicarbonate. As a result, the polymerization is initially essentially initiated by the anhydride peracid components and maintained until the temperature is reached at which the additional organic initiator for the formation of free radicals becomes effective. In this way the polymerization takes place Initiate at the beginning of a polymerization cycle and proceed smoothly to completion.

By correct selection of the initiator components, i.e. by Balancing the reactivity of the theoretically formed diacyl peroxide and the additional organic initiator, can maintain substantially uniform free radical formation throughout the polymerization cycle can be obtained. Such initiator combinations can reduce the rate at which the free radicals are formed from the additional initiator to the extent to which the rate of formation of the free radicals from the theoretically formed diacyl peroxide decreases. The end result is a smooth and continuous one Polymerization with generally shorter polymerization cycles than when using single free radicals Initiators. The reactivity of the organic peroxides can easily be determined by looking at the decomposition rates in a suitable solvent such as white spirit. Also are the responsiveness of most of the commercially available organic peroxides in the literature in terms of half-lives at various Temperatures published.

The amount of the additionally used peroxy compound, for example a peroxydicarbonate, can vary and depends on the amount of the theoretically formed diacyl peroxide, ie ultimately on the amount of acid anhydride and peracid used. As a rule, about 0.001 to about 0.50 Qev.% the additional initiator that forms free radicals,

40981 4/1095

based on the total weight of the monomer. Of the additional free radical-forming organic initiator can be added to the aqueous polymerization medium at any one time Date to be introduced. As a result, it can be used separately or together with the acid anhydride, the peracid, the monomer or the water or the optionally used solvent. Besides, he can separately in the polymerization vessel during the polymerization, e.g. after the polymerization has started and the theoretically formed diacyl peroxide is almost exhausted, to be introduced. The additional initiator is preferred as a mixture with the acid anhydride or the peracid brought in.

Examples of additional initiators which form free radicals are: dialkyl peroxydicarbonates, tertiary Butyl peroxy esters, such as tertiary butyl perpivalate, tertiary butyl perbenzoate, di-tertiary butyl diperphthalate, tertiary Butyl perneodecanoate; other diacyl peroxides such as lauroyl peroxide, benzoyl peroxide, 2,4-dichlorobenzoyl peroxide and Acetylbenzoyl peroxide; Ketone peroxides such as methyl ethyl ketone peroxide, cyclohexanone peroxide and methyl amyl ketone peroxide; organic hydroperoxides, such as cyclohexy! hydroperoxide, Cumene hydroperoxide and tertiary butyl hydroperoxide; and non-peroxidic Initiators such as azobisisobutyronitrile. These initiators are preferably preformed.

The dialkyl peroxydicarbonates can be represented by the formula

0 0

I! Il

R ₄ -OCOOCOR ^

are represented in which R ^ is an aliphatic radical with 1 to 20, preferably 2 to 12 carbon atoms, or an aromatic radical having 6 to 8 carbon atoms. Examples of suitable aliphatic and aromatic radicals are: methyl, ethyl, n-propyl, isopropyl, η-butyl, isobutyl, secondary butyl, tertiary butyl, capryl, 2-ethylhexyl, benzyl,

A098U / 1Q9S

Undecyl, cyclohexyl and 4-tertiary butyl-cyclohexyl. Peroxydicarbonate ester are well known in the art and are commercially available. As a rule, the peroxydicarbonates are produced with careful implementation of the corresponding alkyl chloroformates with aqueous sodium peroxide at low temperatures, e.g. at 0 to 10 ° C, compare e.g. "Journal of American Chemical Society ", Vol. 72, page 1254 (1950) and U.S. Pat. No. 2,370,588.

In a further embodiment of the invention, the additional organic initiator in the polymerization medium mixed with the acid anhydride or the peracid, but are preferably introduced with the acid anhydride. Such new mixtures enable the present process to be used in conjunction with known procedures for the additional initiator in a safe and effective manner, since only the further addition of one or more multiple reagents to the polymerization vessel is required. For example, a mixture of diisopropyl peroxydicarbonate and isobutyric anhydride can be introduced into the polymerization vessel, and the peracetic acid can be separated are fed. These starting materials produce acetylisobutyryl peroxide and diisopropyl peroxydicarbonate as a double initiator system. The amount of each component in this Mixture, i.e. acetic anhydride - organic free radical initiator or peracid - organic free Free radical initiator, of course, will vary depending on the requirements of the particular polymerization reaction. In general, the molar ratio of the acid anhydride or peracid to the organic free one will vary Free radical initiator in the range from 0.05: 1 to 50: 1, with a molar ratio of 0.1: 1 to 20: 1 being preferred.

The invention is explained in more detail in the following examples.

4098U / 1095

Example X

0.8 liter polymerization bottles were charged with 300 g of demineralized and distilled water, 0.3 g of methyl cellulose (Methocel 65 HG-50) as a suspending agent and 0.05 g of sodium bicarbonate. The contents of the bottles were frozen, and then 100 g of liquid vinyl chloride and 0.02 part per 100 parts of vinyl chloride di-n-propyl peroxydicarbonate (NPP) were added to each of the bottles. The bottles were closed and placed in a constant temperature bath of UR) ⁰ C, where they were subjected to a tumbling motion to mix the contents. At various points in time, a bottle was removed from the polymerization bath, the polymerization was quickly interrupted and the contents of the bottle were examined for the degree of conversion of the monomeric vinyl chloride to polyvinyl chloride. The results of these analyzes are given in Table I as a percentage. The polyvinyl chloride obtained was filtered off, washed first with water and then with methanol and then dried in a vacuum oven at 50 ° C.

Example 2

The procedure of Example 1 was repeated with the exception that 0.02 parts of diisopropyl peroxydicarbonate per 100 parts of vinyl chloride were used in place of di-npropyl peroxydicarbonate. In addition, 150 g of vinyl chloride was used in place of 100 g of vinyl chloride. The results the study of the degree of conversion have also been included in Table I.

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3 I. : Conversion Tabel 15th 6.7 Di-n-propyl peroxydicarbonate - 34 Diisopropyl peroxydicarbonate 20.7 Time, h: conversion 73 Time, h 57.3 2 87 2 78.0 4, 2 explain 4th 86.7 6th 8.5 typical polymerizations 9 12th Polymerization bottles with dialkyl 16 17+ Examples 1 and of vinyl chloride in peroxydicarbonates. Example 3

The procedure of Example 1 was repeated with the exception

-4 -4

assume that 8.15 x 10 moles of isobutyric anhydride, 8.15 x

Moles of peracetic acid and 6 χ 10 ~ · ^ moles of sodium bicarbonate in the Polymerization bottles were placed to initiate the polymerization of the vinyl chloride. Such amounts of Theoretically, anhydride and peracid form 0.12 parts of acetylisobutyryl peroxide per 100 parts of monomeric vinyl chloride (phm). The results of this polymerization are shown in Table II and also illustrated graphically in the accompanying figure by the curve representing the small circle markings for 0.12 phm AIP connects.

Table II

Isobutyric anhydride and peracetic acid time, h; % conversion

2 23

4 47

6 54

9 62

16.5 74

4Q98U / 1Q95

From the results of Example 3 it can be seen that vinyl chloride by the combined use of an acid anhydride, i.e., isobutyric anhydride, and a peracid, i.e. peracetic acid, can be polymerized. The results show also that the conversion of vinyl chloride to polyvinyl chloride is higher than that of dialkyl peroxydicarbonates of Example 1 during the first stages of the polymerization cycle. But then the speed of the transformation falls for the anhydride peracid system after about 4 hours away.

Example 4

Attempt a.

The procedure of Example 1 was repeated with the exception that 0.97 x 10 "mol of di-n-propyl peroxydicarbonate (NPP), 4.08 χ 10" ⁴ mol isobutyric anhydride, 4.08 χ ΙΟ " ⁴ mol peracetic acid and 3 x 10 sodium bicarbonate was added to the polymerization bottles to initiate polymerization of vinyl chloride These amounts of anhydride and peracid theoretically make 0.06 parts acetyl isobutyryl peroxide per 100 parts vinyl chloride (phm).

Attempt B

The procedure of Experiment A was repeated with the exception that 0.485 x 10 "moles of di-n-propyl peroxydicarbonate, 8.15 x 10 moles isobutyric anhydride, 8.15 x 10 "^ moles of peracetic acid and 6-10 moles of sodium bicarbonate were used.

Attempt C

The procedure of Experiment A was repeated except that the di-n-propyl peroxydicarbonate was used in an amount of 0.485 x 10 ~ moles was used.

4098U / 1095

The results of Experiments A, B and C are summarized in Table III and also graphically in the attached Figure explained by the curves that follow the marking points with triangles, rectangles and hexagons.

Table III
Attempt a

Initiator system Mol χ 1 (T. 4.08 % Conversion NPP 0.97 30: 18th Isobutyric anhydride 4.08 42 Peracetic acid : Time, h 74 Sodium bicarbonate 2 90 : 4 92 6th 9 16

Attempt B

Initiator system Mole χ 10 ^ 8.15 % Conversion NPP 0.485 60 y 35 Isobutyric anhydride 8.15 54 Peracetic acid : Time, h 87 Sodium bicarbonate : 2 92 ! 4th 92 : 6 9 16

Attempt C

Initiator system Mole 10 4.08: % Conversion NPP 0.485 30! 16 Isobutyric anhydride 4.08: 40 Peracetic acid : Time, h 52 Sodium bicarbonate : 2 85 4th 89 6th 9 16

4098U / 1095

The results of Example 4 show that vinyl chloride is smooth and continuous using a combined initiator system can be polymerized, i.e. an initiator system that has a dialkyl peroxydicarbonate on one side (NPP) and on the other hand an acid anhydride (isobutyric anhydride) and contains a peracid (peracetic acid). The results also show that the rate of polymerization regulated at least in the first half of the polymerization cycle by controlling the amount of each initiator system can be. It follows that this system is sufficiently flexible to accommodate the various cooling capacities of the individual polymerization kettles in the industry.

Example 5

The procedure of Example 1 was repeated. After a Polymerization time of A-, 6 and. 16 hours are each 16, 38 and 9096 of the vinyl chloride batch.

The results of Examples 3 to 5 are shown graphically in FIG attached figure. These results show that the combined use of dialkyl peroxydicarbonate, isobutyric anhydride and peracetic acid monoauric conversions of up to 9O # in just 7 hours, compared to one 50% conversion in 7 hours when using the dialkyl peroxydicarbonate alone. The graph also demonstrates that by using the double Initiator system the polymerization time can be shortened significantly and that the polymerization is smooth at the same time runs.

Example 6

The procedure of Example 1 was repeated with the exception that 150 g of vinyl chloride and 17 x 10 moles of acetic anhydride, 23 x 10 moles of peracetic acid and 6 χ 10 "* ^ moles of Na

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trium bicarbonate to initiate the polymerization of the vinyl monomer were used. After 16 hours of polymerization, 33% of the vinyl chloride was in polyvinyl chloride converted.

Example 7

The procedure of Example 1 was repeated with the exception that 8.15 x 10 moles of n-butyric anhydride, 8.15 x IG

-3
Mol per acetic acid and 6.0 χ 10 mol sodium bicarbonate were used to initiate the polymerization. After a polymerization time of 16 hours, 57% of the monomer had polymerized.

Example 8

The procedure of Example 1 was repeated with the exception that 8.15 x 1 (T ⁴ mol of pivaling anhydride, 8.15 χ ΙΟ " ⁴ mol of peracetic acid and 6 10 mol of sodium bicarbonate were used to initiate the polymerization and the temperature was 20 ° C. After a polymerization time of 16 hours, 1.3% of the monomer had polymerized.

Example 9

The procedure of Example 1 was repeated with the exception

_A _A

assume that 8.15 x 10 moles of acetic anhydride, 8.15 x 10 Moles of perisobutyric acid and 6 10 moles of sodium bicarbonate were used to initiate the polymerization. After a With a polymerization time of 16 hours, 92% of the monomer was converted to the polymer.

Example 10

The procedure of Example 1 was repeated with the exception that 8.15 x 10 moles of isobutyric anhydride, 8.15 x

-4 r- -3

10 moles of perisobutyric acid and 6x10 ^v moles of sodium bicarbonate

A098 U / 1 095

were used to initiate the polymerization. After a polymerization time of 16 hours, 91% of the monomer was

example

The procedure of Example 1 was repeated with the exception that that 0.485 x 10 mol of di-2-ethylbexyl peroxydicarbonate, 4.08 10 mol isobutyric anhydride »4.08 χ 10 mol peracetic acid and 6-10 moles of sodium bicarbonate for initiation the polymerization were used. There were similar conversions obtained as in example 4.

Example 12

The procedure of Example 1 was repeated with the exception that 0.485 x 10 "" moles of di-2-ethylhexyl peroxydicarbonate, 4.08 χ 10 moles of acetic anhydride, 4.08 χ 10 moles of perisobutyric acid and 6-10 moles of sodium bicarbonate were used to initiate the polymerization. There were similar conversions obtained as in example 4.

Example 13

The procedure of Example 1 was repeated with the exception

-U -U

would assume that 8.77 x 10 moles of lauric peroxide, 4.08 χ 10 moles Isobutyric anhydride, 4.08 10 moles of peracetic acid and 6 χ 10 "moles of sodium bicarbonate to initiate the polymerization were used. Conversions of the monomer were satisfactory in polymerization times of 12 to 16 hours obtain.

Example 14

The procedure of Example 1 was repeated with the exception that 2.16 χ 10 mol of tertiary butyl peroxypivalate, 4.08

-4-4

χ 10 mol isobutyric anhydride, 4.08 χ 10 mol peracetic

AQ98U / 1Q95

acidic and 6-10 moles of sodium bicarbonate to initiate the Polymerization were used. Satisfactory conversions were obtained after polymerization times of 12 to 16 hours.

Example 15

The procedure of Example 1 was repeated with the exception that 8.15 x 10 "moles of isobutyric anhydride, 8.15 x 10" moles of peracetic acid, and 6 χ 10 "^ moles of sodium bicarbonate were used to initiate the polymerization of vinyl chloride and the polymerization was carried out at 30 ° C became. After polymerization times of 4, 6, 9 and 17.5 hours, conversions of the monomer of 6, 24, 62 and 88% obtain.

Example 16

The procedure of Example 1 was repeated except that 8.15 x 10 "moles of isobutyric anhydride, 8.15

-4 / - -3

χ 10 moles of peracetic acid and 6 χ 10 moles of sodium bicarbonate were used to initiate the polymerization and the polymerization was carried out at 40 ° C. After 2, 4, 6, At 9 and 16 hours, conversions of the monomer of 12, 41, 65, 92 and 93% were obtained.

4098U / 1095

Claims (1)

Patent claims : 1. Process for polymerizing ethylenically unsaturated compounds by forming free radicals Initiator, characterized in that the initiator used is a combination of an acid anhydride and an organic Peroxyacid used. 2. The method according to claim 1, characterized in that the acid anhydride of the formula 0 O II II R ₁ -COCR ₂ corresponds, in which R-, and R _{2 are} a substituted or unsubstituted C ₁ - Cp ₀ alkyl., Cg - C- ^ ₀ cycloalkyl and Cg '- C, Q aryl radical. 3. The method according to claim 1 or 2, characterized in that the organic peroxy acid of the formula • 0 Jl R ₃ -COOH _{corresponds, in which R 1 is} an unsubstituted or substituted C-, - Cp 0 alkyl or C ^ - - C-, _Q aryl radical. 4. The method according to any one of claims 1 to 3, characterized in that that about 0.001 to about 3% by weight of acid anhydride, based on the ethylenically unsaturated compound, can be used and that the molar ratio of the acid anhydride to the peroxyacid is about 0.1: 1 to about 5: 1 amounts to. 5. The method according to claim 1, characterized in that an additional organic free radical forming Initiator is used. A098U / 1095 6. The method according to claim 5, characterized in that the additional initiator in the temperature range from 45 to about 80 ° C forms radicals with good effect. 7. The method according to claim 6, characterized in that the free radical initiator is a tertiary butyl peroxyester, Diacyl peroxide, peroxydicarbonate ester or • is azobisisobutyronitrile. 8. The method according to claim 7, characterized in that the peroxydicarbonate of the formula 0 0 If Il R ₄ -OCOOCOR ₄ corresponds, in which R _{4 is} an aliphatic radical having 2 to carbon atoms or an aromatic radical having 6 to carbon atoms. 9. The method according to claim 5, characterized in that the additional initiator in amounts of 0.001 to about 0.50% by weight, based on the weight of the ethylenically unsaturated compound, is used. 10. Process for polymerizing ethylenically unsaturated monomers by initiators which form free radicals in an aqueous medium at about 0 to about 90 ° C, characterized in that for initiation and up ' right maintenance of the polymerization an acid anhydride, a organic peroxy acid and an alkaline buffering agent introduced into this medium in an amount sufficient to "in. situ" an initiating amount of a diacyl · to form peroxides. " 11. The method according to claim 10, characterized in that the acid anhydride of the formula "', 4 0 9 8 U /. 1: Q 9 S * ■■; -r BATH ORIGINAL corresponds, in which R ₁ and Rp are unsubstituted or substituted C ₁ - Cp ₀ alkyl, Cg - C ₁₀ cycloalkyl or Cg - C aryl radicals. 12. The method according to any one of claims 10 or 11, characterized in that that the organic peroxyacid of the formula corresponds, in which R ^ is an unsubstituted or substituted C-, - CpQ alkyl or Cr - C ₁₀ aryl radical. 13. The method according to any one of claims 10 to 12, characterized in that that about 0.001 to about 3% by weight of acid anhydride, based on the ethylenically unsaturated monomer, are used and that the molar ratio of the acid anhydride to the peroxyacid is from about 0.1: 1 to about 5: 1, 14. The method according to any one of claims 10 to 13, characterized in that that 0.001 to about 0.50% by weight, based on the monomer, of an additional free radical forming Initiator from the group of tertiary butyl peroxyesters, diacyl peroxides, peroxydicarbonate esters and azobisisobutyronitrile be used, 15. Process for polymerizing vinyl chloride in one aqueous medium with an initiator which forms free radicals, characterized in that the polymerization stimulated and maintained by an initiator system becomes »aas (&} about 0.001 to about 3 % by weight, based on vinyl chloride »of an acid anhydride of the formula Q 0
ti η Κ- »« · C «· O ·· ■ C- ■ * Rp, in which R ^ mka Rg are each a C ₁ - G ₂ Q alkyl · »* Cg each C ^ - C _iQ aryl radical» 4Q98UVT09S (b) an organic peroxy acid of the formula Il R ₃ -COOH in the R ^ a C, - C ₉₀ alkyl or Cg - C _1Q aryl group, wherein the ratio of acid anhydride and Mo peroxyacid 0.1: 1 to about 5: 1 and corresponds! (c) 0.01 to about 10% by weight based on vinyl chloride, of one contains alkaline buffering agents. 16. The method according to claim 15, characterized in that the acid anhydride isobutyric anhydride and the peroxy acid Is peracetic acid. 17. The method according to claim 15, characterized in that 0.001 to about 0.50% by weight, based on vinyl chloride, of a peroxydicarbonate ester of the formula 0 0 ft ti R ₄ -OCOOCOR ₄ in which R _{4 is} an aliphatic radical having 1 to 20 carbon atoms is used. 18. Composition for initiating the polymerization of ethylenically unsaturated compounds, characterized in that that it is an acid anhydride of the formula 0 0
1: ti R ₁ -COCR ₂ in which R- and Rp are each an unsubstituted or substituted C ₁ -C ^ q alkyl, Cg _{-C 10} cycloalkyl or C- aryl radical, and a peroxydicarbonate ester of the formula 0 0 Il ti R ₄ -OCOOCGR ₄ in which R _{4 is} an aliphatic radical with 1 to 20 carbon atoms or. aromatic radical with 6 to 8 carbon atoms, is »contains * where the molar ratio of the acid anhydride xmä the peroxydlcarbonate ester is 0.1: 1 to 20: 1. Ä0S8U / TO95 19. Composition according to claim 1, characterized in that that it is an organic peroxyacid of the formula 0
R ₃ -COO-II in which R ^ is an unsubstituted or substituted C-, -C-alkyl- or Cg-C ₁₀ aryl radical, and a peroxydicarbonate ester of the formula 0 0 H H R ₄ -OCOOCOR ₄ in "where R _{4 is} an aliphatic radical having 1 to 20 carbon atoms or an aromatic radical having 6 to 8 carbon atoms, the ratio of the acid anhydride to the peroxydicarbonate ester being 0.1: 1 to 20: 1. 34. Blank page