MXPA00004879A

MXPA00004879A - Process for preparing polymers

Info

Publication number: MXPA00004879A
Application number: MXPA/A/2000/004879A
Authority: MX
Inventors: Shuhua Wu Richard; Lewis Brown Jeffrey; Patrick Stack Dennis
Original assignee: Rohm And Haas Company
Priority date: 1999-05-21
Filing date: 2000-05-18
Publication date: 2002-05-09

Abstract

This invention relates to a process for preparing polymers which contain as polymerized units hydrophobic monomers wherein a stable emulsion is formed and the formation of suspension particles is minimized. The process includes making a concentrated monomer emulsion, diluting the concentrated monomer emulsion with water, feeding the diluted monomer emulsion to a reactor, and polymerizing the monomer.

Description

F PROCESS FOR PREPARING POLYMERS This invention relates to a process for preparing polymers. In particular, the invention relates to a process for preparing polymers containing, as polymerized units, hydrophobic monomers. As used herein, a hydrophobic monomer is understood to mean a monomer containing an ester of (meth) acrylic acid C 8 to C 4 or a monomer with low solubility in water, such as styrene. By (meth) acrylic is meant both acrylic and methacrylic. The polymers can be obtained by various processes, which include polymerization in solution and in emulsion. Many polymerization processes in solution use organic solvents, while emulsion polymerization processes use water and surfactants. Due to environmental problems with respect to volatile organic compounds, emulsion polymerization processes are preferred. Until recently, polymers containing hydrophobic monomers as polymerized units were only known through the processes of solution polymerization. This was due to the difficulties with the emulsion polymerization processes. There are three problems associated with the emulsion polymerization of hydrophobic monomers. The first problem is that it is difficult to disperse the hydrophobic monomer in water and transport the monomer to the forming polymer. The second problem is in the formation of monomer droplets small enough to obtain a stable emulsion of monomers. The third problem is that some polymers in suspension, which have a larger particle size than the emulsion polymer form. The suspension polymer may cause problems, such as the formation of a "cream" layer on the top of the latex or a sedimentation layer on storage. The suspension polymer can also cause problems in the properties of the downstream application. Therefore, there is a need for a process for preparing polymers, which contain, as a polymerized unit, hydrophobic monomers, in which a stable emulsion is obtained, the formation of the polymer in suspension is minimized. An approach of the emulsion polymerization to disperse the hydrophobic monomer and transport it to polymer formation is taught in U.S. Patent No. 5,521,266. The process disclosed in that patent generates a latex, and uses the cyclodextrin to transport the monomer through the water phase to the polymer phase. The monomer and cyclodextrin are combined in an emulsion with a monomer concentration ranging from 69 to 77 weight percent. The monomer emulsion was not pre-diluted before being fed to the reactor. A problem associated with the approach of U.S. Patent No. 5,521,266 is that some particles are formed in suspension. Another problem associated with this approach is that the dilution of concentrated emulsion of monomers with water, a highly viscous dispersion is formed. The high viscosity requires more energy to disperse the emulsion of monomers in the reactor and, therefore, there is a greater cost in stirring the dispersion during the polymerization. If higher rates of agitation are used in the reactor, there will be a potential for late coagulation of the latex. U.S. Patent No. 3,637,563 discloses a process for preparing polymers which may contain, as polymerized units, hydrophobic monomers. Process is designed to obtain polymer emulsions that contain a higher solids content. The process includes previously mixing the monomers, surfactants and water in a tank, to form a concentrated emulsion of monomers, then feeding the concentrated emulsion of monomers, containing from 75 to 94 per cent by weight of monomers, to a reactor. which contains water and polymerize the monomers. The process does not include a step of pre-diluting the concentrated emulsion of monomers with water through a mixer, before feeding the monomer emulsion to the reactor. Therefore, the process has the problem of forming a highly viscous dispersion in the dilution of the concentrated emulsion of monomers with water. U.S. Patent No. 3,296,168 discloses a continuous process for preparing polymers. The process uses an in-line mixer to continuously create an emulsion of monomers from a charge of monomers and a second charge of the surfactant and water. A process for preparing polymers from concentrated emulsions of monomers containing hydrophobic monomers of (meth) acrylic acid esters is not described. U.S. Patent No. 4,355,142 discloses a process for preparing monomer emulsions to obtain polyvinyl chloride latex. The process uses online cutting elements to prepare the monomer emulsion. The reference reveals a drastic reduction in the accumulation of the polymer on the inside of the reactor and the clot in the latex. This reference does not describe the applicability of this process to hydrobonic monomers. Despite the descriptions of the references, there is a continuing need for a process of preparing polymers containing, as hydrophobic monomer polymerized units, in which the stable emulsion is formed and the formation of the suspended polymer is minimized. The present invention provides a process that includes the preparation of a concentrated emulsion of monomers, which includes at least one dimer; dilute the concentrated emulsion of monomers with water; feeding the diluted emulsion of monomers to a reactor; and polymerizes the monomers. As indicated above, the first step in the process of the invention involves preparing a "concentrated emulsion of monomers." Concentrated means an emulsion of monomers containing from 76 to 95 weight percent, preferably from 80 to 90 percent by weight. The monomer is combined with water and with emulsifying or dispersing agents to form the concentrated emulsion of monomers.This concentrated emulsion of monomers can be prepared by mixing the monomers, water and emulsifying or dispersing agents in the monomer. Alternatively, the concentrated emulsion of monomers can be prepared through the use of in-line mixers.The on-line mixer process is characterized by the separate feed of monomers and a solution of water and emulsion or dispersion agents continuously fed to through an in-line mixer, contained in this line, and then to the reactor.The preferred mixers are mixers of lt cut, such as, but not limited to, a high-cut IKA d mixer with multiple teeth (ULTRA-TURRAX in similar line), or X Series Mixer Emulsifiers, 400 Series, IN-LINE, by Charles Ross & They are Company. This class of mixers can produce high cut and densified energy in a small space, to emulsify the monomer in water. The concentrated emulsion of monomers can also be prepared using a high pressure homogenizer. The homogenizer is a device that pumps monomers, water and a surfactant agent through a valve at alt pressure. The pressure typically varies - from 70 to 2100 kg / cm2. Suitable homogenizers include, but are not limited to, those of EmulsiFLex, such as EmulsiFlex C-160 or EmulsiFlex C-50. The emulsifying or dispersing agents used for the preparation of the concentrated emulsions of monomers can be of the anionic, cationic or non-ionic type. Likewise, a mixture of either of two types d may be used. Suitable non-ionic emulsifiers include, but are not limited to, ethoxylated octylphenols, ethoxylated nonylphenols, similar ethoxylated fatty alcohols. Suitable anionic emulsifiers include, but are not limited to, sodium lauryl sulfate, sodium dodecylbenzene sulphonate, sulphated ethoxylated derivatives of nonylphenols, octylphenols and fatty alcohols, esterified sulfosuccinates and the like. Suitable cationic emulsifiers include, but are not limited to, laurylpyridinium chlorides, cetyldimethyl amine acetate, (C 8 -C 18) alkyldimethylbenzylammonium chlorides, and the like. The level of the emulsifier can be from about 0.1 to 10% by weight, based on the total charged monomers. Among the monomers which may be useful in the concentrated emulsion of the enamel are the erillenically unsaturated monomers, including, but not limited to, the monomers of (meth) acrylic esters, such as methyl acrylate, ethyl acrylate, butyl, 2-ethylhexyl acrylate, decyl acrylate, methyl methacrylate, butyl methacrylate, hydroxyethyl acrylate hydroxypropyl methacrylate; substituted acrylamide or acrylamide; styrene or substituted styrenes; vinyl acetate or other vinyl esters; vinyl monomers, such as vinyl chloride, yinylidene chloride, N-vinyl pyrrolidone; and acrylonitrile or methacrylonitrile. Butyl acrylate, methyl methacrylate and styrene are preferred. Monomers containing ethylenically unsaturated acids, or their salts, may also be useful. These suitable monomers containing ethylenically unsaturated acids include, but are not limited to, acrylic acid, methacrylic acid, crotonic acid, methacrylate d-phospholethyl, 2-acrylamido-2-methyl-1-propansulphonic acid, sodium vinyl sulfonate, acid itaconic, fumaric acid, maleic acid, moncmethyl aconate, monomethyl fumarate, monobutyl fumarate and. maleic anhydride. S prefer acrylic acid and methacrylic acid. Especially preferred is methacrylic acid. The ethylenically unsaturated monomers of fluorinated (meth) acrylate, such as Zonyl ™ products, (trademark of DuPont Chemical Company) may also be useful. This at least one monomer can also be an ethylenically unsaturated, silicone-containing monomer, such as vinytri-trimethoxy-silane and methacryloxy-propyl trimethoxy-silane. Selected monomers of (C6-C20) alkyl and alkyl-alpha-methyl-styrene, (C3-C20) alkyl dialkyl itaconate, vinyl esters (C10-C20) of carboxylic acids, N-alkyl (Ca-C20) -acylamide and methacrylamide, alkyl alpha hydroxymethylacrylate (C10-C20), 2,2 ' dialkyl (oxydimethylene) diacrylate (C8-C20), 2,2 ' dialkyl (C 8 -C 20) alkyl (alkyliminodimethylene), N (C 8 -C 20) alkyl-acrylamide and (C 10 -C 20) alkyl vinyl ether may also be useful. Hydrophobic monomers, such as (C12-C40) alkyl esters of (meth) acrylic acid, may also be useful as is this at least one monomer, used in the process of this invention. Suitable alkyl esters of (meth) acrylic acid include, but are not limited to, lauryl C (meth) acrylate, cetyl (meth) acrylate, stearyl (meth) acrylate, behenyl (meth) acrylate. (meth) icosyl acrylate. In a preferred embodiment, the amount of the hydrophobic monomer ranges from 10 to 99 percent by weight, preferably from 20 to 90 percent by weight, more preferably from 30 to 80 percent by weight. When hydrophobic monomers are included in the monomer emulsion, it is preferred to use 0.1 to 20 weight percent, preferably 0.2 to 10 weight percent, more preferably 0.5 to 2 weight percent, of a compound selected from cyclodextrin and cyclodextrin derivatives; cyclic oligosaccharides having a hydrophobic cavity, such as cycloinulohexose, cycloinuloheptose and cycloinuloctose; calixarenos; cavitands, as the phase transport catalysts, to transfer the droplets of monomers to the polymer of formation. The phase transport catalysts, useful in the method of the invention, are limited only by the solubility of the cyclodextrin and the cyclodextrin derivative, selected under particular polymerization conditions. Suitable cyclodextrins, useful in the method of the present invention, include, but are not limited to, α-cyclodextrin, β-cyclodextrin and α-cyclodextrin. cyclodextrin. Suitable cyclodextrin derivatives, useful in the method of the present invention include, but are not limited to, the hydroxypropionium and hydroxyethyltriacetyl and methyl derivatives of the α-cyclodextrin, β-cyclodextrin α-cyclodextrin. The preferred derivative of cyclodextrin is methyl β-cyclodextrin. • Cyclic oligosaccharides, having a hydrophobic cavity, such as cycloinulohexose, cycloinulheptose, useful in the method of the invention, are described by Takai et al., In Journal of Organic Chemistry, 1994, volume 59, number 11, pages 2967-2975. The calixarenes useful in the method of the invention are described in U.S. Patent No. 4,699,996, International Patent Publication W 89/08092 and Japanese Patent Publications 1988/197544 and 1989/007837. Cavitands useful in the method of the invention are described in Italian application 22522 A / 89 and Moran et al., Journal of the Chemical Chemical Society, volume 184 1982, pages 5826-5828. Non-cyclic polysaccharides, their derivatives and their degradation products, which are capable of forming inclusion compounds, can also be useful as phase transport catalysts. Such materials can be useful from 1 to 20 weight percent. The phase transport catalysts can be mixed with water and emulsifiers or dispersants in the reactor, before feeding the diluted emulsion of monomer to the reactor. Alternatively, the phase transport catalysts can be mixed with the monomer or concentrated emulsion of monomers. The phase transport catalysts can also be co-fed with water and the emulsifiers or dispersants into the reactor while the diluted emulsion of monomers is fed to the reactor. An interleaver, selected from an encrelator agent and an interlacing monomer, may also be incorporated into the polymers obtained by the process of this invention. By "interleaver" is meant a compound which has at least 2 reactive groups, which will react with the acid groups found in the monomers of the compositions of this invention. The interlacing agents useful in the polymers obtained by the process of this invention, include a polyaziridine, polyisocyanate, polycarbodiimide, polyamine and a polyvalent ün-meta. This interlacing agent is optional and can be added after the polymerization has been completed. . The crosslinking monomers are crosslinkers which are incorporated with other monomers. These crosslinking monomers which may be useful with the polymers obtained by the process of this invention include the functional monomers of acetoacetate, such as acetoacetoxyethyl acrylate, steel methoxylate acetoxypropyl, acetoacetoxyethyl methacrylate, allyl acetoacetate, acetoacetoxybutyl methacrylate methacrylate 2, 3-di (acetoacetoxy) propyl; divinyl benzenes, (meth) acryloyl polyesters of polyhydroxy compounds, divinyl esters of polycarboxylic acids, diallyl esters of polyacryboxylic acids, diallyl dimethyl ammonium chloride, triallyl terephthalate, methylene bis acrylamide, d-diallyl maleate, diallyl fumarate, hexamethylene-bis-maleamide, triallyl phosphate, trivinyl trimellitate, divinyl adipate, glyceryl trimethacrylate, diallyl succinate, divinyl ether, divinyl ethers of ethylene glycol diacrylate of diethylene glycol, diacrylates or polyethylene glycol methacrylates, 1,6-hexanediol diacrylate, triacrylate or pentaerythritol tetraacrylate, neopentyl glycol diacrylate, cyclopentadiene diacrylate, butylene glycol diacrylates or dimethacrylates, trimethylolpropane di- or tri-acrylates, (met ) acrylamide, (meth) acrylamide of n-ethylol, their mixtures and the like. The (meth) acrylamide, n-methylol, (meth) acrylamide and their mixtures are preferred. The amount of the interleaver used is selected so that this interlacing does not interfere with the formation of the film. There are many advantages in using an inline mixer, to create an emulsion of monomers. An advantage of using in-line mixers is that a better mix of additives can be achieved.

For example, chain transfer agents, such as n-DDM are normally emulsified with water monomers / surfactant in the emulsion tank of monomers. However, n-DDM can initiate undesirable dangerous polymerization in the monomer emulsion tank, when impurities are present. Process additives, such as chain transfer agents, polymerization inhibitors and others, can be fed continuously into the in-line mixer, to ensure a good mix, before entering the reactor. Normally, low levels of process additives are used in emulsion polymerizations. Achieving a good mix of small amounts of additives directly in the large reactor can be difficult. If high stirring rates are used in the large reactor to mix the additives, it is not only expensive, but also has the potential to induce latex cutting coagulation. In-line mixers have small mixing volumes and, therefore, mix well. A second advantage of online mixing is that in-line mixers provide the ability to change monomers or other charge compositions continuously. With online mixing, the order of water addition, agent emulsifier or dispersant, and monomer can change , as required by the process. The compositions of monomer and emulsifying or dispersing agent can be changed by means of overlapping or pulsed charges. The overlap feed is understood as two monomer emulsions with different types of monomers (concentrations) and different surfactants (streams A and B) simultaneously fed into the reactor. The charge ratio of the current A to the current B (Rf) can start at 0.5 and be changed to 20 or more, during the last stage of the charge. By pulse feeding, it is understood that the concentrations of monomers rise to a higher level in the emulsion of monomers for a short period of time, during charging, then the concentration of this monomer returns to its normal concentration. It would be difficult to achieve this by having a monomer emulsion tank because, although the concentration of monomers can easily be increased by adding monomers to the tank, the monomer concentration is difficult to reduce, because it would require a dilution. This process would be very expensive with multiple monomer emulsion tanks. The process can be easily done with the in-line mixture alone, which is equipped with multiple loading lines of monomers or with the combination of the in-line mixture and an emulsion tank of monomers. During the emulsion polymerization, the monomer composition fed to the reactor can be changed continuously by feeding different amounts of monomer A and monomer B into the in-line mixer at a given time. In this case, monomer A and monomer B, water and emulsion or dispersion agent are fed directly from their individual storage tanks into the in-line mixer. Therefore, it is possible to have the concentration of monomers in such an emulsion of monomers in 100% of the monomer A at the start of the charge, 50% of the monomer A and 50% of the monomer B in the average point of the charge, and 100% of monomer B at the end d load.

The ratio of monomer A to monomer B can be changed linearly or in any desired profile, to achieve any combination of desired compositions. This kind of flexibility can only be achieved easily by mixing online. The second step of the process of the invention is to dilute the concentrated emulsion of monomers with water. The dilution must take place before feeding the concentrated emulsion of monomers to the reactor. In general, the amount of water - added to the concentrated monomer emulsion is sufficient to dilute the amount of monomers in the emulsion from 10 weight percent to 80 weight percent, preferably from 40 to 80 weight percent, more preferably from 60 to 80 weight percent. We have found that the way in which dilution is performed is important. The concentrated emulsion of monomers can be diluted with water in a tank equipped with stirring means, feeding the concentrated monomer and water through a "T", or feeding the concentrated emulsion of monomers and water to a static mixer. The diluted emulsion of monomers can be fed to a storage tank and then fed to the reactor, it can be fed directly to the reactor. Generally, on-line mixing of the water and the concentrated emulsion of monomers is preferred. By mixing online means that the materials are mixed in the line that feeds the reactor. The inline mixer can be a "dynamic mixer or a static mixer." Dynamic mixer means a mixer with moving parts, such as a small tank, cop a stirrer Other suitable dynamic mixers include, but are not limited to, those designed by Ross or IKA, described above Static mixers are preferred for this process Static mixer means a mixer if moving parts Suitable static mixers include, but are not limited to, those of Sulzer Chemtech AG, as the type - SMV, SMX type and SMXL type; and those of Chemimeer, which include the Kenics HEC mixer and the Kenics KMS mixer. After dilution of the concentrated emulsion of monomers, this diluted emulsion of monomers is fed into the reactor and reacts to form a polymer. The reactor may be a stirred tank reactor, a tubular reactor, a spiral heat exchanger, a plate and frame heat exchanger, or a plate and fin heat exchanger. The monomer emulsions are typically fed with a pump. It is known in the art that the monomer emulsion can be fed to the reactor through a positive displacement pump, such as a Waukesha bomb. It is also known that a centrifugal bomb can be used for these purposes. The process of the invention can be used for polymerizations in solution, suspension or emulsion. The process is particularly useful for polymerizations and emulsion. Emulsion polymerizations are well known in the art and are described in U.S. Patent No. 5,436,954, which is incorporated herein by reference. Suitable initiators and process conditions can be found in that patent. This at least one monomer can be fed as a single monomer from the above list, or it can be any combination thereof.

The chain transfer agents can be used to control the molecular weight of the polymer obtained by the process of this invention. Suitable chain transfer agents include mercaptans, such as, for example, dodecyl mercaptan ("n-DDM"). The chain transfer agent can be used at a rate of up to 10% based on the total weight of the polymeric composition .. Through this specification and the claims, unless otherwise indicated, the references to percentages are by weight and all temperatures are given in degrees centigrade.It will also be understood that, for the purposes of this specification and the claims, the limits of the ranges and relationships, indicated herein, are combinable, for example, - if intervals of 1-20 and 5-15 are mentioned for a particular parameter, it will be understood that the intervals of 1-15 or of 5-20 are also considered.The following abbreviations and trademarks are used through this specification: RPM = revolutions per minute, g = grams, Na22C03 sodium carbonate, Na2S203 = sodium persulfate, FeS04 ferrous sulfate, t-BHP = tertiary butyl hydroperoxide, cm2 = square centimeters. The following examples attempt to illustrate the process of the invention. The axes should not be construed as limiting the scope of the invention.

Example 1. - Minor Concentration of the Monomer in the Emulsion • A seed loading of the monomer emulsion was prepared as follows: a 500 ml jar was equipped with a magnetic stirrer. To the jar were added 1.10 g of the sodium salt of the fatty alkyl ether sulfate, 139.0 g of water, 46.0 g of lauryl methacrylate, 45.0 g of methyl methacrylate, 10.0 g of butyl acrylate and 1.0 of methacrylic acid. This charge was vigorously stirred during the addition time. An emulsion of monomers was prepared as follows: a 4-liter laboratory cuvette was equipped for vigorous mechanical mixing, using a top agitation motor. A solution of surfactant was obtained in the cuvette, using 495 g of water, 30.6 g of the sodium salt of alkyl ether sulfate grade and 133.0 g of polyethoxylated dodecyl alcohol. An amount of 1900 g of stearyl methacrylate was heated to 35 ° C and then slowly added to the surfactant solution under vigorous mechanical mixing (350 RPM). Stearyl methacrylate was added slowly enough so that the emulsion did not break, in about 5 minutes. Once the addition of stearyl methacrylate was complete, 102 g of methyl methacrylate and 41.0 g of methacrylic acid were added. Stirring was continued through the addition. The polymer was prepared as follows: a 5-liter neck flask was equipped with a mechanical stirrer, condenser and three load lines. The flask was charged with 525 g of water and heated to 87 ° C. When the temperature was stabilized, the following was added: 31_2 g of the sodium salt of the fatty alkyl ether sulfate, 41.00 g of a 51% solution of methyl-β-cyclodextrin, a buffer solution (7.20 g, Na2CO3 / 40.00 g of water) and an initiator solution (7.20 g of Na2S208 / 35.00 g of water). After the addition of these fillers, the seeding of the monomer emulsion was fed through a line emulsifier (adjusted to 3500 RPM) to the reaction over 20 minutes. When the seeding addition was complete, a copper additive consisting of 41.00 g of a 51% solution of methyl-β-cyclodextrin and 30.00 g of water was added to the flask. The monomer emulsion was then fed through a high-cut in-line mixer (adjusted at 3500 RPM) to the flask over a period of three hours, while maintaining the temperature at 79-81 ° C. Separate charges of the catalyst (1.10 g- of Na2S208 in 110.00 g of water) and water (500 g) were added to the flask in 3 hours. When the addition of the monomer emulsion was complete, the residual monomer was reacted by adding, in succession, solutions of 0.02 g of FeSO4 / 5.00 g of water, 4.00 g of 70% t-BHP / 35.00 g of water, and 2.07 g of isoascorbic acid / 50.0 g of water. The emulsion was then neutralized by adding a solution of 9.5 g of aqueous ammonia in 10.0 g of water.

Example 2 - Greater Concentration of the Monomer in the Emulsion A seed charge of the rimeric emulsion was prepared as follows: a 500 ml jar was equipped with a magnetic stirrer. To the jar were added 1.10 g of the sodium salt of the fatty alkyl ether sulfate, 139.0 g of water, 46.0 g of lauryl methacrylate, 45.0 g of methyl methacrylate, 10.0 g of butyl acrylate and 1.0 g of methacrylic acid. This charge was vigorously stirred during the addition time. An emulsion of monomers was prepared as follows a 4 liter laboratory cuvette was equipped for vigorous mechanical mixing, using a top agitation motor. A surfactant solution was obtained in the cuvette, using 180 g of water, 30. & g of the sodium salt of alkyl ether sulfate grade and 133.0 g of polyethoxylated dodecyl alcohol. An amount of 1900 g of stearyl methacrylate was heated to 35 ° C and then slowly added to the surfactant solution under vigorous mechanical mixing (350 RPM). Stearyl methacrylate was added slowly enough so that the emulsion did not break, in about 5 minutes. Once the addition of stearyl methacrylate was complete, 102 g of methyl methacrylate and 41.0 g of methacrylic acid were added. Stirring was continued through the addition.

The polymer was prepared as follows: a 5-liter neck flask was equipped with a mechanical stirrer, condenser and three load lines. The flask was charged with 840 g of water and heated to 87 ° C. When the temperature was stabilized, the following was added: 31.2 g of the ether salt of fatty alkyl ether sulfate, 41.00 g of a 51% solution. % of methyl-β-cyclodextrin, a buffer solution (7.20 g, Na2CO, / 35.00 g of water) and an initiator solution (7.20 g of Na2S208 / 35.00 g of water) After the addition of these fillers, sowing of the monomer emulsion was fed through an online emulsifier (adjusted to 3500 RPM) to the reaction over 20 minutes. When the seeding addition was complete, a copper additive, consisting of 41.00 g of a 51% solution of methyl-β-cyclodextrin and 30.00 g of water was added to the flask. The monomer emulsion was then fed through a high cut in-line mixer (adjusted at 3500 RPM) to the flask over a period of three hours, while maintaining the temperature at 79-81 ° C. Separate charges of the catalyst (1.10 g of Na2S2Oa in 110.00 g of water) and water (500 g) were added to the flask in 3 hours. When the addition of the monomer emulsion was complete, the residual monomer was reacted by adding, in succession, solutions of 0.02 FeSO4 / 5.00 g of water, 4.00 g of 70% t-BHP / 35.00 gd water, and 2.07 g. of isoascorbic acid / 50.0 g of water. The emulsion was then neutralized by adding a solution of 9.5 aqueous ammonia in 10.0 g of water.

Example 3 - High Concentration of the Monomer in the Emulsion, Which is Then Previously Diluted With Water A seed charge of the monomer emulsion was prepared as follows: a 500 ml jar was equipped with a magnetic stirrer. To the jar were added 0.10 g of the sodium salt of the fatty alkyl ether sulfate, 139.0 g of water, 46.0 g of lauryl methacrylate, 45.0 g of methyl aethacrylate, 10.0 g of butyl acrylate and 1.0 g of methacrylic acid. . This charge was vigorously agitated during the addition time. An emulsion of monomers was prepared as follows: an aqueous solution of surfactant was obtained using 180 g of water, 30.6 g of the sodium salt of the alkyl ether sulfate grade and 133.0 g of polyethoxylated dodecyl alcohol. A separate solution was obtained in a 4 liter cubet, taking 1900 g of stearyl methacrylate, which had been heated to 35 ° C and adding 102.0 g of methyl methacrylate and 41.0 g of methacrylic acid. When the polymerization began, these two solutions were simultaneously fed through the in-line emulsifier in a 3-hour period. The polymer was prepared as follows: a necked flask, of 5 liters, was equipped with a mechanical agitator, or condenser and two load lines. The flask was charged with 525 g of water and heated to 87 ° C. When the temperature was stabilized, the following was added: 31.2 g of the sodium salt of the fatty alkyl ether sulfate, 41.00 g of a 51% solution of methyl-β-cyclodextrin, a buffer solution (7.20 g, Na2CO3 / 40.00 g of water) and an initiator solution (7.20 g of Na2S208 / 35.00 g_of water)? After the addition of these fillers, the seeding of the monomer emulsion was fed through an in-line emulsifier (set at 3500 RPM) to the reaction over 20 minutes. When the seeding addition was complete, a copper additive, consisting of 41.00 g of a 51% solution of methyl-β-cyclodextrin and 30.00 g of water was added to the flask. L Concentrated monomer emulsion was prepared by passing the previous aqueous load and the previous monomer charge through the online emulsifier (set at 3500 RPM). L concentrated emulsion of monomers then was passed through d a static mixer, where it was mixed continuously- in a 3-hour period with a water load (465 g), pair form the diluted emulsion of monomers, which is fed to the flask. Additions were made while maintaining temperature at 79-81 ° C. A separate charge of catalyzed (1.10 g of Na2S208 in 465 g of water) was added simultaneously to the flask in 3 hours. When the addition of the monomer emulsion was complete, the monomer was reacted by adding, in succession, 0.02 solutions g of FeSO4 / 5.00 g of water, 4.00 g of 70% t-BHP / 35.00 g d water, and 2.07 g of isoascorbic acid / 50.0 g of water. L emulsion was then neutralized by adding a solution of 9.5"V .. of aqueous ammonia in 10.0 g of water. twenty Results The polymers prepared above were analyzed in the formation of particles in suspension. Using micrographs taken from the latex, a count was taken of the number of large suspended particles (defined as particles having a diameter greater than 2.0 microns). The results are shown in Table 1.

Table 1 Example Suspended Particles Large Particles / cm2 i 10 0.10 2 14 0.14 3 2 0.02 The visual inspection of the photographs also showed a significant reduction in the number of particles in suspension of intermediate size (defined here as particles with diameters ranging from 0.5 to 2.0 micas)

Claims

CLAIMS 1. A process, which comprises: preparing a concentrated emulsion of monomers, comprising at least one monomer; dilute the concentrated emulsion of monomers with water, feed the diluted solution of monomers to the reactor; and, polymerize the monomers.
2. The process according to claim 1, wherein the concentrated emulsion of monomers comprises at least one hydrophobic monomer and the concentrated emulsion of monomers is diluted with water in an in-line mixer.
3. The process, according to claim 2, wherein the hydrophobic monomer is selected from (meth) lauryl acrylate, cetyl (meth) acrylate, stearyl (meth) acrylate, behenyl (meth) acrylate, (meth) icosyl acrylate, styrene and α-methyl styrene; the in-line mixer is selected from a dynamic mixer and a static mixer; and a compound selected from the group consisting of the cyclodextrin and derivatives thereof; cyclic oligosaccharides having a hydrophobic cavity, such as cycloinulohexose, cycloinuloheptose, cycloinuloctose; calixarenos; and cavitands, are used as a phase transport catalyst.
4. The process, according to claim 3, wherein the in-line mixer is a static mixer.
The process, according to claim 4, wherein the reactor is selected from a stirred tank reactor, a tubular reactor, a heat exchanger and C 10 spiral, - a plate and frame heat exchanger and a plate and fin heat exchanger.
6. The process, according to claim 5, wherein the reactor is a stirred tank reactor.
7. The process according to claim 1, wherein the emulsion of concentrated monomers comprises from 76 to 95 weight percent of this monomers a monomer.
8. The process, according to claim 1, t¿. wherein the emulsion of concentrated monomers comprises from 80 to 90 weight percent of this at least one monomer.
9. The process according to claim 8, wherein the emulsion of concentrated monomers is diluted with water, so that the amount of the monomer in the diluted emulsion is between 40 and 80 weight percent.
10. The process, according to claim 9, in which the emulsion of concentrated monomers is diluted 5 with water, so that the amount of the monomer in the diluted emulsion is between 60 and 80 per cent by weight. F \ I: