MXPA98009447A

MXPA98009447A - Procedure for preparing emulsions of polymers, and the polymers formed of mi

Info

Publication number: MXPA98009447A
Application number: MXPA/A/1998/009447A
Authority: MX
Inventors: Mitchell Blankenship Robert; Keith Bardman James
Original assignee: Rohm And Haas Company
Priority date: 1997-11-20
Filing date: 1998-11-12
Publication date: 1999-06-01

Abstract

A process for preparing multi-step emulsion polymers is disclosed. This process is capable of producing multistage, multi-stage emulsion polymers, which have low bulk density. These polymers are useful in coating compositions, such as

Description

PROCEDURE FOR PREPARING EMULSIONS OF POLYMERS. AND THE POLYMERS FORMED THEREOF The present invention relates to processes for preparing emulsions of polymers and to polymers formed thereof. In particular, the present invention relates to aqueous emulsion polymerization processes for preparing emulsions of polymers and to polymers formed thereof. "Polymer in-emulsion", as used herein, refers to a water-insoluble polymer, which is prepared by emulsion polymerization techniques. "Polymer emulsion", as used herein, refers to an aqueous composition having discrete, water-insoluble, dispersed polymer particles. As used herein, acrylate and methacrylate are named as "(meth) acrylate", and acrylic and methacrylic acid are referred to as "(meth) acrylic acid". Emulsion polymers, such as hollow or evacuated emulsion polymers, are known in their use in various industrial applications. The literature uses the terms "hollow" and "evacuated" interchangeably. These polymers are often used in paints, coatings, inks, sunscreens and papermaking. The hollow emulsion polymers are generally prepared by swelling a core / shell emulsion polymer, such that one or more voids are formed within the emulsion polymer particles. These voids contribute, among other things, to the opacity of coatings and films prepared with the hollow emulsion polymer. For some applications, it is particularly convenient to minimize the weight of the applied coating. For example, it is desirable that certain applications of paper coatings have a high performance coating without considerably adding paper weight. Therefore, it is convenient to provide lightweight, low density additives for coatings, such as the latex particles evacuated. The evacuated latex particles can be prepared by any of several known processes, including those described in the patents of US Pat. Nos. 4,427,836, 4,468,498, 4,594,363, 4,880,842, 5,492,971, 5,521,253, 5,157,084, 5,360,827, among others. The evacuated latex particles, as described in the aforementioned references, are prepared by swelling the core of a core-shell emulsion polymer. Some of the processes, such as that described in U.S. Patent No. 5,360,827, describe processes by which, in later stages of the polymerization of the shell, the monomer is added to facilitate diffusion of the base in the core of the shell. polymer, in order to achieve the swelling. Then, the pH of the emulsion is adjusted with a monomer containing a carboxyl group, which is subsequently polymerized. However, this process consumes time and does not result in suitable, lightweight emulsion polymers. The present invention seeks to overcome the deficiencies in previously known processes by supplying evacuated emulsion polymers, low density, and a process for their preparation. In a first aspect of the present invention, a process for preparing emulsion polymer particles is provided, this process comprises: a) supplying an aqueous emulsion of i) a multistage emulsion polymer, comprising a polymer from the step of core and a polymer of the shell stage, wherein the polymer of the core stage comprises, as polymerized units, from 5 to 100 weight percent, based on the weight of the polymer of the core stage, of a monomer monoethylenically unsaturated hydrophilic, and from 0 to 95 parts by weight, based on the weight of the polymer of the core stage, of at least one non-ionic, monoethylenically unsaturated monomer; and wherein the polymer of the shell stage comprises, as polymerized units, at least 50 weight percent of the non-ionic, monoethylenically unsaturated monomer.; ii) a monomer, at a level of at least 0.5 percent by weight, based on the weight of the multi-stage emulsion polymer; and iii) a swelling agent under conditions in which there are no substantial polymerizations of the monomer; and b) reducing the monomer level by at least fifty percent. In a second aspect of the present invention, an aqueous emulsion of polymers is provided, comprising water and swollen, multi-stage emulsion polymers, in which the dry bulk density of the multi-stage swollen emulsion is: less than 0.77 grams per cubic centimeter ("g / cc"), when the swollen, multistage emulsion polymer has a particle size below 275 nanometers ("nm"), - less than 0.74 g / cc when the swollen emulsion polymer , multi-stage, has a particle size of 275 to 500 nm; less than 0.59 g / cc when the swollen, multi-stage emulsion polymer has a particle size of 501 to 750 nm; less than 0.46 g / cc, when the swollen, multi-stage emulsion polymer has a particle size of 751 to 1300 nm. The stages of the multi-stage polymers of the present invention include the polymer of the core stage (the "core") and the polymer of the shell stage. (the cover"). The core and the cover can, by themselves, be comprised of more than one stage. There are also one or more intermediate stages. Preferably, the multi-stage polymer comprises a core, an intermediate layer and a cover. The nuclei of the multistage polymers of the present invention are emulsion polymers compris as polymerized units, from 5 to 100 weight percent, based on the weight of the core, of at least one hydrophilic, monoethylenically unsaturated monomer , and from 0 to 95 weight percent, based on the weight of the polymer of the core stage, of at least one non-ionic, monoethylenically unsaturated monomer. The cores, which contain at least five percent by weight, based on the total weight of the core polymer, of at least one hydrophilic, monoethylenically unsaturated monomer, will generally result in an adequate degree of swell There may be cases in which, due to the hydrophobicity of certain comonomers or their combinations, in conjunction with the hydrophobic / hydrophilic balance of a particular hydrophilic monomer, the copolymer can be suitably prepared with less than five weight percent, based on in the total weight of the core polymer, of a monoethylenically unsaturated hydrophilic monomer. It is preferred that the core comprises, as polymerized units, a monoethylenically unsaturated hydrophilic monomer, at a level of from 5 to 100, more preferably from 20 to 60 and especially preferred from 30 to 50 weight percent, based on the total weight of the core. The hydrophilic core polymer can be obtained in a se step or step of the sequential polymerization or can be obtained by a plurality of steps in sequence. The multistage emulsion polymer of the present invention considers a core polymer in which at least one hydrophilic, monoethylenically unsaturated monomer polymerizes alone or with at least one monoethylenically unsaturated, nonionic monomer. This process also considers and includes in the term "monoethylenically unsaturated hydrophilic monomer", the use of a non-polymeric compound, which contains at least one carboxylic acid group, which is absorbed in the core polymer, before, duror after the polymerization of the hydrophobic shell polymer, as a replacement for the monoethylenically unsaturated hydrophilic monomer in the hydrophilic core polymer, as described in U.S. Patent No. 4,880,842. In addition, this invention considers and includes within the term "monoethylenically unsaturated hydrophilic monomer", the use of a latent hydrophilic core polymer, which does not contain a monoethylenically unsaturated hydrophilic monomer, but which can be swollen in hydrolysis to a polymer of hydrophilic core, as described in the patent of US Pat. No. 5,157,084 Suitable monoethylenically unsaturated hydrophilic monomers, useful for obtainthe core polymer, include the monoethylenically unsaturated monomers containacid functionality, as monomers containat least one carboxylic acid group, includacrylic acid, methacrylic acid, acryloxypropionic acid, (meth) acryloxypropionic acid, itaconic acid, aconitic acid, maleic acid or anhydride, fumaric acid, crotonic acid, maleate monomethyl, monomethyl fumarate, monomethyl itaconate, and the like. Acrylic acid and methacrylic acid are preferred. Suitable non-polymeric compounds containat least one carboxylic acid group include aliphatic or aromatic monocarboxylic (C6-C12) acids and dxcarboxylic acids, such as benzoic acid, m-toluic acid, p-chlorobenzoic acid, or acetoxybenzoic acid, azelaic acid, sebacic acid, octanoic acid, cyclohexanecarboxylic acid, lauric acid and monobutyl phthalate and the like. Nonionic, monoethylenically unsaturated monomerssuitable, to obtain the hydrophilic core polymer include styrene, a-methyl-styrene, p-methyl-premiere, t-butyl-styrene, vinyltoluene, ethylene, vinyl acetate, vinyl chloride, vinylidene chloride, (meth ) acrylonitrile, (meth) acrylamide, esters of alkyl (Cl-C20) or (C3-C20) alkenyl of (meth) acrylic acid, such as methyl (meth) acrylate, ethyl (meth) acrylate, (met ) butyl acrylate, 2-ethylhexyl (meth) acrylate, hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, benzyl (meth) acrylate, lauryl (meth) acrylate, oleyl (meth) acrylate, ( methy) palmityl acrylate, stearyl (meth) acrylate, and the like. The core, when obtained by a one-stage process or a process involving several stages, has an average particle size of 50 nm to 1.0 miera, preferably 100 to 300 nm in diameter in the non-inflated condition. If the core is obtained from a seed polymer, this seed polymer preferably has an average particle size of 30 to 200 nm. The core may also optionally contain less than 20 weight percent, preferably 0.1 to 3 weight percent, based on the total weight of the core, of a polyethylenically unsaturated monomer, wherein the amount used is, in general, approximately proportional to the amount of the hydrophilic, unsaturated monoethylenically unsaturated monomer used; in other words, as the relative amount of the hydrophilic monomer increases, it is acceptable to increase the level of the polyethylenically unsaturated monomer. Alternatively, the core polymer may contain 0.1 to 60 weight percent, based on the total weight of the core polymer, of the butadiene. Suitable monomers, polyethylenically unsaturated, include the comonomers which contain at least two addition polymerizable vinylidene groups and which are ethylenically unsaturated monocarboxylic, alpha, beta-unsaturated esters of polyhydric alcohols containing 2-6 ester groups. Such comonomers include alkylene glycol diacrylates and dimethacrylates, such as, for example, ethylene glycol diacrylate, ethylene glycol dimethacrylate, 1,3-butylene glycol diacrylate, 1,4-butylene glycol diacrylate, diacrylates. of propylene glycol and triethylene glycol dimethacrylate; 1,3-dimethacrylate glycerol, 1,1-trimethylol propane dimethacrylate, 1,1,1-trimethylol ethane diacrylate; pentaerythritol trimethacrylate; 1, 2, 6-hexane triacrylate; sorbitol pentamethacrylate; methylene bis-acrylamide, methylene bis-methacrylamide, divinyl benzene, vinyl methacrylate, vinyl crotonate, vinyl acrylate, viol acetylene, trivinyl benzene, triallyl cyanurate, divinyl acetylene, divinyl ethane, sulfur divinyl, divinyl ether, divinyl sulfone, diallyl cyanamide, ethylene glycol divinyl ether, diallyl phthalate, divinyl dimethyl silane, glycerol trivinyl ether, divinyl adipate; dicyclopentenyl (meth) acrylates; dicyclopentenyloxy (meth) acrylates; unsaturated esters of glycol monodicyclopentenyl ethers; allyl esters of α, β-unsaturated mono- and dicarboxylic acids, having a terminal ethylenic unsaturation, including allyl methacrylate, allyl acrylate, diallyl maleate, diallyl fumarate, diallyl itaconate, and the like. The multistage polymer of the present invention preferably contains an intermediate step. The polymer of the intermediate stage, when present, encapsulates, partially or completely, the core and by itself is partially or fully encapsulated by the shell. The intermediate stage is prepared by conducting an emulsion polymerization in the presence of the core. The intermediate stage preferably contains, as polymerized units, from 0.3 to 20, more preferably from 0.5 to 10 weight percent, based on the weight of the core, of at least one hydrophilic, monoethylenically unsaturated monomer. The intermediate step preferably contains, as polymerized units, from 80 to 99.7, more preferably from 90 to 99.5 weight percent, based on the weight of the intermediate step, of at least one non-ionic, monoethylenically unsaturated monomer. The hydrophilic, monoethylenically unsaturated monomers, and the monoethylenically unsaturated nonionic monomers, useful in obtaining the core, are also useful in obtaining the intermediate layer. The multistage polymer shell of this invention is the product of the emulsion polymerization of 80 to 100, preferably 90 to 100, percent by weight, based on the total weight of the shell, of at least one nonionic monomer , monoethylenically unsaturated. Non-ionic, monoethylenically unsaturated monomers suitable for the core are also suitable for the shell. Styrene is preferred. The cover may also contain, as polymerized units, from 0 to 20, preferably from 0 to 10, percent by weight, based on the weight of the shell, of one or more monoethylenically unsaturated monomers, containing acid functionality, for get the cover of the hydrophobic polymer, which includes acrylic acid, methacrylic acid, acryloxypropionic acid, acid (meth) acryloxypropionic, itaconic acid, aconitic acid, maleic acid, maleic anhydride, fumaric acid, crotonic acid, monomethyl maleate, monomethyl fumarate, monomethyl itaconate, and the like. Acrylic acid and methacrylic acid are preferred. The monomers used and their relative proportions in the shell should be such that they are permeable to a basic swelling agent, volatile or fixed, aqueous or gaseous, capable of inflating the core. Monomeric mixtures to obtain the shell, preferably contain from 0.1 to 10% by weight, based on the total weight of the shell polymer, of a monoethylenically unsaturated, functional acid monomer. Preferably, the proportion of the monoethylenically functional unsaturated monomer of acid in the shell polymer will not exceed one third of its proportion in the core polymer. The presence of the monoethylenically unsaturated acid functional monomer in the shell polymer can serve several functions: (1) stabilize the polymer in a multi-stage final emulsion; (2) ensuring the permeability of the cover to a swelling agent; and (3) compatibilizing the cover with the previously formed stage of the multi-stage emulsion polymer. As used herein, the term "sequentially emulsion polymerization" or "sequentially produced emulsion" refers to polymers (including homopolymers and copolymers) that are prepared in the aqueous medium by a polymerization process in the emulsion, in the presence of dispersed polymer particles of an emulsion polymer, previously formed, so that the emulsion polymers, previously formed, increase in size by depositing there of the emulsion polymerized product of one or more successive monomer charges , introduced into the medium containing the dispersed particles of the preformed emulsion polymer. In sequential emulsion polymerization, to which the present invention is related, the term "seed" polymer is used to name an aqueous dispersion of the emulsion polymer, which may be the initially formed dispersion, which is the product of a one-step emulsion polymerization, or it may be the dispersion of the emulsion polymer obtained at the end of any subsequent step, except the final stage of the sequence polymerization. Thus, a hydrophilic core polymer, which here is intended to be encapsulated by one or more subsequent steps of the emulsion polymerization, can itself be named a seed polymer for the next step. The method of this invention considers that the core, the intermediate stage, the cover or any combination thereof, can be obtained in a single step or step of the polymerization in sequence, or can be obtained by a plurality of steps in sequence, immediately after polymerization. The first step of the emulsion polymerization in the process of the present invention can be the preparation of a seed polymer containing small, dispersed polymer particles, insoluble in the aqueous emulsion polymerization medium. This seed polymer may or may not contain any hydrophilic monomer component but supplies particles of minute size, which form the nuclei in which the hydrophilic core polymer is formed, with or without the nonionic comonomer. An initiator of a free radical, soluble in water, is used in the aqueous emulsion polymerization. Suitable initiators of free radial, soluble in water, include hydrogen peroxide; tertiary butyl peroxide; alkali metal persulfates, such as sodium, potassium and lithium persulfate, ammonium persulfate; and mixtures of these initiators with a reducing agent. Reducing agents include: sulfites, such as meta-bisulfite, hydrosulfite and alkali metal hyposulfite; sodium formaldehyde sulfoxylate; and reducing sugars, such as ascorbic acid and isoascorbic acid. The amount of the initiator is preferably 0.01 to 3 weight percent, based on the total amount of the monomer and in a redox system, the amount of the reducing agent is preferably 0.01 to 3 weight percent, based on the amount Total monomer. The temperature can be in the approximate range of 10 to 100 ° C. In the case of the persulfate systems, the temperature is preferably in the range of 60 to 90 ° C. In the redox system, the temperature is preferably in the range of 30 to 70 ° C, preferably below about 60 ° C, more preferably in the range of 30 to 45 ° C. The type and amount of the initiator may be the same or different in the various stages of the multistage polymerization. One or more nonionic or anionic emulsifiers, or surfactants, may be used, either alone or in combination. Examples of suitable nonionic emulsifiers include tere. -octylphenoxyethyl poly (39) -ethoxyethanol, dodecyl oxypoly (10) ethoxyethanol, nonylphenoxyethyl-poly (40) ethoxyethanol, polyethylene glycol monooleate 2000, ethoxylated castor oil, fluorinated alkyl esters and alkoxylates, polyoxyethylene (20) -sorbitan monolaurate, sucrose monococoate, di (2-butyl) phenoxypoly (20) ethoxyethanol, hydroxyethylcellulose polybutyl acrylate graft copolymer, dimethyl silicone-poly-alkylene oxide graft copolymer, poly (ethylene oxide) poly (ethylene oxide) block copolymer butyl acrylate, block copolymers of propylene oxide and ethylene oxide, 2, 4, 7, 9-tetramethyl-5-decin-4,7-diol ethoxylated with 30 moles of ethylene oxide, N-polyoxyethylene (20) lauramide, N-lauryl-N-polyoxyethylene (3) amine and poly (10) ethylene glycol dodecyl thioether Examples of suitable anionic emulsifiers include sodium lauryl sulfate, sodium dodecylbenzenesulfonate, potassium stearate, dioctyl sulfosuccinate sodium, disulf sodium dodecyl diphenyloxide sodium, nonylphenoxyethyl poly (1) ethoxyethyl sulphonate ammonium salt, sodium styrene sulfonate, sodium dodecyl allyl sulfosuccinate, flaxseed oil fatty acid, sodium or ammonium salts of nonylphenyl phosphate esters ethoxylate, octoxynol-3-sodium sulfate, sodium cocoyl sarcocinate, sodium 1-alkoxy-2-hydroxy-p-phenyl sulphonate, alpha-olefin (C14-C16) -sulfonate sodium, sulfates of hydroxyalkanols, N- (1, 2-dicarboxy-ethyl) -N-octadecylsulfosuccinamate, N-octadecylsulfosuccinate disodium, alkylamido-polyethoxy-sulfosuccinate disodium, nonylphenol ethoxylated disodium half-ester of sulfosuccinic acid and sodium salt of tere. -octylphenoxyethoxy-poly (39) ethoxyethyl sulfate, The one or more surfactants are generally used at a level of 0 to 3 percent, based on the weight of the multi-stage polymer. The one or more surfactants can be added before the addition of any monomer charge, during the addition of a monomer charge or a combination thereof. In certain monomer / emulsifier systems to form the shell, the tendency to produce gum or clot in the reaction medium can be reduced or impeded by the addition of about 0.05 to 2.0% by weight, based on the total weight of the polymer of cover, of the emulsifier without impairing the deposition of the polymer formed in the previously formed core particles. The amount of the emulsifier can be zero, in the situation where a persulfate initiator is used, up to 3 weight percent, based on the total weight of the core polymer. By carrying out the emulsion polymerization while maintaining low levels of the emulsifier, subsequent steps of polymer formation deposit the more recently formed polymer in the existing dispersed polymer particles resulting from the preceding step or step. As a general rule, the amount of the emulsifier must be kept below that which corresponds to the critical concentration of micelles for a particular monomer system, but while this limitation is preferable and produces a unimodal product, it has been found that in some systems, the critical concentration of micelles of the emulsifier can be somewhat exceeded without the formation of an objectionable or excessive number of micelles or dispersed particles. It is in order to control the number of micelles during the various stages of polymerization, so that the deposit of the polymer formed subsequently in each stage occurs in the micelles or dispersed particles, formed in the previous stages, that the concentration of the emulsifier is maintained. low. The viscosity - average molecular weight of the polymer formed in a given step can vary from 100,000, or less if a chain transfer agent is used, to several million molecular weight. When 0.1 to 20% by weight, based on the weight of the monomer, of n polyethylenically unsaturated monomer, mentioned above, is used to obtain the core, the molecular weight is increased whether or not interleaving occurs. The use of polyethylenically unsaturated monomers reduces the tendency of the core polymer to dissolve when treating the multi-stage polymer with a swelling agent for the core. If it is desired to produce a core with a molecular weight in the lower part of the range, such as from 500,000 to as low as about 20,000, it is often more practical to do so by avoiding the polyethylenically unsaturated monomers and instead using a heat transfer agent. chain, such as 0.05 to 2% or more, examples being alkyl mercaptans, such as secondary butyl mercaptan. The weight ratio of the core to the intermediate stage, if present, is generally in the range of 1:05 to 1:10, preferably in the range of 1: 1 to 1: 7. The weight ratio of the core to the shell is generally in the range of 1: 5 to 1:20, preferably in the range of 1: 8 to 1:15. When it comes to decreasing the dry density of the final product, it is preferred to have as little cover as possible and still encapsulate the core. The amount of the polymer deposited to form the cover polymer is generally such as to provide a general particle size of the multistage polymer, from 70 nm to 4.5 microns, preferably from 100 nm to 3.5 microns, more preferably from 200 nm to 2.0. microns, in the non-swollen condition (ie, before any neutralization, to raise the pH to about 6 or greater) if the shell polymer is formed in a single step or in a plurality of stages. In order to minimize the dry density of the final product, it is preferable to deposit only as much cover polymer as necessary to completely encapsulate the core. When the hydrophilic core polymer is completely encapsulated, it is not titrated with metal bases. alkaline under normal analytical conditions of about 1 hour and at room temperature. The extent of the encapsulation can be determined by removing the samples during the course of the polymerization of the shell and titrating with sodium hydroxide.

The multistage emulsion polymer is prepared by the emulsion polymerization in sequence, which, as discussed above, includes charging the monomers forming the shell. At or near the conclusion of charging the monomers forming the shell, the contents of the reactor include the multi-stage polymer, water and the unreacted monomer. Under the conditions of an emulsion polymerization, there is also an appreciable free radical content, or radical flow, which keeps the polymerization process active. Even if no additional monomer or initiator is added, there is an appreciable free radical content in the system. When there is no appreciable free radial content, in other words, when the radical flow is very low or close to zero, then a substantial amount of polymerization will not occur. We have discovered that this free radical content interferes with the extent of swelling that can be achieved. Previously known processes achieve the swelling in a typical manner, by adding a suitable swelling agent in the last stages of loading the monomers, which form the cover or upon completion of loading the monomers, which form the cover. It is believed that the presence of the unreacted monomer facilitates the transport of the swelling agent to the core. However, in previously known processes, the swelling agent is added to the system while there is an appreciable free radical content in the system. Thus, under those conditions, a substantial amount of polymerization will still occur. We have discovered that by supplying an aqueous emulsion of the multistage emulsion polymer, monomer and swelling agent, under conditions in which there is no substantial polymerization of the monomer, we can intensify the swelling extent of the multistage emulsion polymer. There are many resources so that substantial polymerization of the monomer does not occur, including the addition of one or more polymerization inhibitors, the addition of one or more reducing agents, waiting for a sufficient period of time until there is no longer an appreciable number of monomers. free radicals by virtue of which they end up by cooling the contents of the reactor to limit the reactivity of free radicals, and their combinations. A preferred recourse includes the addition of one or more polymerization inhibitors, such as, for example, N, N-diethyl-hydroxylamine, N-nitrosodiphenylamine, 2,4-dinitrophenylhydrazine, p-phenylenediamine, phenathiazine, alloocmene, phosphite triethyl, 4-nitrosophenol, 2-nitosophenyl, p-aminopheol, 4-hydroxy-TEMPO (also known as free radical of 4-hydroxy-2, 2,6,6,6-tetramethylpiperidinyloxy), hydroquinone, p-methoxyhydroquinone, tere. -butyl-p-hydroquinone, 2,5-di-tert. -butyl-p-hydroquinone, 1,4-naphthalenediol, 4-tert. -butyl catechol, copper sulfate, copper nitrate, resol and phenol. When used, the polymerization inhibitors or reducing agents are added in an effective amount to substantially stop any polymerization, generally from 25 to 5,000 parts per million ("ppm"), preferably from 50 to 3,500 ppm based on the solids of the polymer. Preferably, the polymerization inhibitors or reducing agents are added while the multi-stage polymer is at or below the temperature at which the cover was poreized, more preferably within ten degrees Celsius below the temperature at which the cover was polymerized. . The monomer that is present in, or after ensuring that no substantial polymerization of the monomer occurs, can be (i) one or more of the monomers used to prepare any of the multi-stage polymer steps, (ii) one or more monomers , in addition to those used to prepare any of the multi-stage polymer steps or (iii) their combinations. Preferably, the monomer present at such time is one or more of the monomers used to prepare the shell. Such a monomer may be an unreacted monomer of the multistage emulsion polymer preparation, it may be added separately, or a combination thereof.

Preferably, the monomer is of the non-ionic type. This nonionic monomer is preferred because the functional acid monomers will be neutralized by a swelling agent and those neutralized monomers are difficult to remove by polymerization. Preferably, the level of the monomer present in, or after being certain that no substantial polymerization of the monomer occurs, is 1 to 20 times as much as the monomer level established during the polymerization. It is also necessary to use one or more swelling agents. Suitable swelling agents include those which, in the presence of the multistage emulsion polymer and monomer, are capable of permeating the shell and swelling of the core. The swelling agents may be volatile or fixed, aqueous or gaseous bases, or combinations thereof. Suitable swelling agents include volatile bases, such as ammonia, ammonium hydroxide and volatile lower aliphatic amines, such as morpholine, trimethylamine and triethylamine, and the like; fixed or permanent bases, such as potassium hydroxide, lithium hydroxide, zinc and ammonium complex, copper ammonium complex, silver and ammonium complex, strontium hydroxide, barium hydroxide, and the like. Solvents, such as, for example, ethanol, hexanol, octanol, Texanol® solvent and those described in U.A. Patent No. 4,594,363 can be added to aid in setting or penetration of the permanent base. Ammonia and ammonium hydroxide are preferred. When attempting to maximize the extent of swelling, it is preferred that one or more swelling agents be added after ensuring that substantial polymerization of the monomer does not occur. The amount of the swelling agent may be less, equal to or greater than the amount necessary to provide complete neutralization of the core. Preferably, the amount of the swelling agent is in the range of 75 to 300 percent, more preferably in the range of 90 to 250 percent, based on equivalents of functionality in the core, capable of being neutralized. It is also preferred to add one or more swelling agents to the multistage emulsion polymer, while this multistage emulsion polymer is at an elevated temperature, preferably at a temperature within 10 ° C of the polymerization temperature of the shell. The swelling is generally very efficient under high temperature conditions, in the presence of monomers and without substantial polymerization occurring. Under these conditions, the swelling is generally complete within 30 minutes, preferably within 20 minutes, more preferably within 10 minutes of addition of one or more swelling agents. The core polymer of the multistage emulsion polymer swells when this core is subjected to a basic swelling agent, which permeates the shell, to neutralize, at least partially, the hydrophilic functionality of the core, preferably at a pH of at least about 6 to 10, and thus results in hydration swelling by the hydrophilic core polymer. The swelling, or expansion, of the core may involve partial melting of the outer periphery of the core in the pores of the inner periphery of the shell and also the partial buckling or enlargement of the shell and the whole particles in general. When the swollen, multi-stage emulsion polymer is dried, the water and swelling agent are removed from the central region of the swollen, multi-stage emulsion polymer, the core tends to shrink and evacuation develops, whose extension depends on the resistance of the roof to the restoration to its previous size. This resistance of the cover to self-restoration to its previous size is critical to minimize the dry volumetric density of the multi-stage swollen emulsion polymer. The expansion of the core results in the expansion of the roof equally.

As the size of the cover is restored to its previous size, it increases the volumetric density in dry. Therefore, it is desirable to minimize the extent to which the size of the cover is restored, thus maximizing the dry bulk density of the swollen, multi-stage emulsion polymer. This can be achieved by reducing the monomer level. It is believed that the presence of monomers is useful in facilitating swelling of the multi-stage polymer, by plasticizing the cover, aiding in transport through the cover, or a combination thereof. However, the presence of the monomer is detrimental when it comes to maximizing swelling and minimizing the dry bulk density of the multi-stage swollen emulsion polymer. Therefore, after swelling of the emulsion polymer, multi-stage, in the presence of both the monomer and the swelling agent, it is convenient to reduce the monomer level to less than 10,000 ppm, preferably less than 5,000 ppm, based on in the polymer solids. This can be accomplished by any suitable means. Preferably, the monomer level is reduced by the polymerization of the monomer. This can be accomplished by any suitable resource, such as by adding one or more initiators, such as those mentioned above. It is preferred to begin reducing the monomer level within 20 minutes, more preferably within 10 minutes, of adding the one or more swelling agents. The process of the present invention is capable of producing swollen, multi-stage emulsion polymers, which have very low bulk density. Swollen, multi-stage emulsion polymers having a particle size below 175 nm can be prepared with a dry bulk density of 0.30 to 0.77 g / cc, preferably 0.35 to 0.76 g / cc, more preferably 0.40. at 0.75 g / cc. The swollen, multi-stage emulsion polymers, having a particle size in the range of 275 to 500 nm, can be prepared with a dry bulk density of 0.30 to 0.74 g / cc, preferably 0.35 to 0.73 g. / cc, more preferably from 0.40 to 0.72 g / cc. The swollen, multi-stage emulsion polymers, having a particle size in the range of 501 to 750 nm, can be prepared with a dry bulk density of 0.30 to 0.59 g / cc, preferably 0.35 to 0.58 g / cc , more preferably from 0.40 to 0.57 g / cc. The swollen, multi-stage emulsion polymers having a particle size in the range of 751 to 1,300 nm can be prepared with a dry bulk density of 0.30 to 0.46 g / cc, preferably 0.35 to 0.45 g / cc, more preferably from 0.40 to 0.44 g / cc.

When the swollen, multi-stage emulsion polymers are dried, at least partially, to produce evacuated polymer particles, these evacuated polymer particles impart favorable properties, such as brightness, lightness and opacity to paper coating formulations at which are added. The evacuated latex particles, produced by the method of the present invention, are useful in coating compositions, such as water based paints and paper coatings. The evacuated polymer particles, produced by the method of this invention, impart improved gloss, lightness and opacity to the paper coating formulations to which they are added. Likewise, the evacuated polymer particles, produced by the method of this invention, impart opacity to aqueous coating compositions, such as paints, to which they are added.

Example 1: A core was prepared as follows: a round-bottom, four-necked, 5-liter capacity flask was equipped with a paddle stirrer, thermometer, nitrogen inlet and reflux condenser. Deionized water was added, 1760 grams, to the kettle and heated to 86 ° C under a nitrogen atmosphere. An emulsion of monomers (EM) was prepared by mixing 720 grams of deionized water, 6.5 grams of sodium dodecylbenzenesulfonate (SDS, 23%), 10.0 grams of methacrylic acid and 780.0 grams of methyl methacrylate. From this MS, 164 grams were removed and placed separately. To the remaining MS were added 71.2 grams of SDS (23%) and 510 grams of methacrylic acid. With the copper water at 86 ° C - a mixture of 160 grams of deionized water, 10.4 grams of SDS (23%) and 20.5 grams of Plurafac® B-25-5 (Plurafac is a trademark of BASF), followed by the MS removed from the initial ME, and then followed by a mixture of 5.5 grams of sodium persulfate in 40 grams of deionized water, were added to the copper. The contents of the copper were stirred for 15 minutes. The remaining MS was then fed to the pan over a period of two hours, at 85 ° C. After completing the loading of monomers, the dispersion was maintained at 85 ° C for 15 minutes, cooled to 25 ° C and filtered to remove any clot. The filtered dispersion had a pH of 3.0, a content of 30.3% solids and an average particle size of 145 nm.

Example 2; A core was prepared as follows: a round-bottom, four-neck, 5-liter capacity flask was equipped with a paddle stirrer, thermometer, nitrogen inlet and reflux condenser. Deionized water, 1760 grams, was added to the kettle and heated to 86 ° C under a nitrogen atmosphere. An emulsion of monomers (EM) was prepared by mixing 720 grams of deionized water, 2.7 grams of the surfactant Abex® CO-436 (Abex is a trademark of Rhone Poulenc), 10.0 grams of methacrylic acid and 780.0 grams of methyl methacrylate. From this MS, 164 grams were removed and placed separately. To the remaining MS were added 14.5 grams of Abex CO-436 and 510 grams of methacrylic acid. With the copper water at 86 ° C, a mixture of 160 grams of deionized water and 1.40 grams of Abex® CO-436, followed by the EM removed from the initial EM, and then followed by a mixture of 5.5 grams of persulphate sodium in 40 grams of deionized water, were added to the copper. The contents of the copper were stirred for 15 minutes. The remaining MS was then fed to the pan over a period of two hours, at 85 ° C. After completing the loading of molymers, the dispersion was maintained at 85 ° C for 15 minutes, cooled to 25 ° C and filtered to remove any clot. The filtered dispersion had a pH of 2.8, a content of 31.4% solids and an average particle size of 146 nm.

Example 3; A core was prepared as follows: a round-bottom, four-neck, 5-liter capacity flask was equipped with a paddle stirrer, thermometer, nitrogen inlet and reflux condenser. Deionized water, 1760 grams, was added to the kettle and heated to 86 ° C under a nitrogen atmosphere. An emulsion of monomers (EM) was prepared by mixing 720 grams of deionized water, 2.7 grams of the surfactant Abex® CO-436, 10.0 grams of methacrylic acid and 780.0 grams of methyl methacrylate. From this MS, 164 grams were removed and placed separately. To the remaining MS were added 27.0 grams of Abex CO-436 and 510 grams of methacrylic acid. With the copper water at 86 ° C, a mixture of 160 grams of deionized water, 4.0 grams of Abex® CO-436 and 20.0 grams of Plurafac® B-25-5, followed by the EM removed from the initial EM, and then followed by a mixture of 5.5 grams of sodium persulfate in 40 grams of deionized water, were added to the copper. The contents of the copper were stirred for 15 minutes. The remaining MS was then fed to the pan over a period of two hours, at 85 ° C. After completing the loading of monomers, the dispersion was maintained at 85 ° C for 15 minutes, cooled to 25 ° C and filtered to remove any clot. The filtered dispersion had a pH of 2.7, a content of 31.9% solids and an average particle size of 153 nm.

Example 4; A core was prepared as follows: a round-bottom, four-neck, 5-liter capacity flask was equipped with a paddle stirrer, thermometer, nitrogen inlet and reflux condenser. Deionized water, 1700 grams, was added to the kettle and heated to 80 ° C under a nitrogen atmosphere. An emulsion of monomers (EM) was prepared by mixing 335 grams of deionized water, 14.0 grams of sodium dodecylbenzenesulfonate (SDS, 23%), 4.5 grams of methacrylic acid and 364.5 grams of methyl methacrylate. From this MS, 82 grams were removed and placed separately. To the remaining MS were added 7.0 grams of SDS (23%) and 241 grams of methacrylic acid. With the copper water at 80 ° C, the MS removed from the initial EM was added to the kettle, followed by the addition of a mixture of 2.75 grams of sodium persulfate in 15 grams of deionized water. The contents of the copper were stirred for 15 minutes. The remaining MS was then fed to the pan over a period of two hours, at 85 ° C. After completing the loading of monomers, the dispersion was maintained at 80 ° C for 15 minutes, cooled to 25 ° C and filtered to remove any clot. The filtered dispersion had a pH of 3.1, a content of 22.1% solids and an average particle size of 184 nm.

Example 5: A core was prepared as follows: a 5-liter, four-necked round bottom flask was equipped with a paddle stirrer, thermometer, nitrogen inlet and reflux condenser. Deionized water, 1760 grams, was added to the kettle and heated to 86 ° C under a nitrogen atmosphere. An emulsion of monomers (EM) was prepared by mixing 720 grams of deionized water, 2.7 grams of the surfactant Abex® CO-436, 10.0 grams of methacrylic acid and 780.0 grams of methyl methacrylate. From this MS, 164 grams were removed and placed separately. To the remaining MS were added 9.0 grams of Abex CO-436 and 510 grams of methacrylic acid. With the copper water at 86 ° C, a mixture of 160 grams of deionized water, 4.0 grams of Abex® CO-436 and 20.0 grams of Plurafac® B-25-5, followed by the EM removed from the initial EM, and then followed by a mixture of 5.5 grams of sodium persulfate in 40 grams of deionized water, were added to the copper. The contents of the copper were stirred for 15 minutes. The remaining MS was then fed to the pan over a period of two hours, at 85 ° C. After completing the loading of monomers, the dispersion was maintained at 85 ° C for 15 minutes, cooled to 25 ° C and filtered to remove any clot. The filtered dispersion had a pH of 2.8, a content of 31.6% solids and an average particle size of 171 nm.

Example 6: A core was prepared as follows: a round-bottom, four-necked, 5-liter capacity flask was equipped with a paddle stirrer, thermometer, nitrogen inlet and reflux condenser. Deionized water, 1700 grams, was added to the kettle and heated to 80 ° C under a nitrogen atmosphere. An emulsion of monomers (EM) was prepared by mixing 335 grams of deionized water, 10.7 grams of the surfactant Disponil® Fes-993 (Disponil is a trademark of Henkel), 4.5 grams of methacrylic acid and 364.5 grams of methyl methacrylate. From this MS, 82 grams were removed and placed separately. To the remaining MS were added 5.40 grams of Disponil® Fes-993 and 241.0 grams of methacrylic acid. With the copper water at 80 ° C, a mixture of 50 grams of deionized water and 10.0 grams of Plurafac®B-25.5, followed by the EM removed from the initial EM, and then followed by a mixture of 2.75 grams of persulfate sodium in 15 grams of deionized water, were added to the copper. The contents of the copper were stirred for 15 minutes. The remaining MS was then fed to the kettle over a period of two hours, at 80 ° C. After completing the loading of monomers, the dispersion was maintained at 80 ° C for 15 minutes, cooled to 25 ° C and filtered to remove any clot. The filtered dispersion had a pH of 3.1, a content of 31.9% solids and an average particle size of 161 nm.

Example 7: A core was prepared as follows: a round-bottom, four-neck, 5-liter capacity flask was equipped with a paddle stirrer, thermometer, nitrogen inlet and reflux condenser. Deionized water, 1700 grams, was added to the kettle and heated to 80 ° C under a nitrogen atmosphere. An emulsion of monomers (EM) was prepared by mixing 335 grams of deionized water, 14.0 grams of sodium dodecylbenzenesulfonate (SDS, 23%), 4.5 grams of methacrylic acid and 364.5 grams of methyl methacrylate. From this MS, 82 grams were removed and placed separately. To the remaining MS were added 7.0 grams of SDS (23%) and 241 grams of methacrylic acid. With the copper water at 80 ° C, a mixture of 50 grams of deionized water and 9.8 grams of Plurafac® B-25-5, followed by the MS removed from the initial ME was added to the copper, and then followed by the addition of a mixture of 2.75 grams of sodium persulfate in 15 grams of deionized water. The contents of the copper were stirred for 15 minutes. The remaining MS was then fed to the kettle over a period of two hours, at 80 ° C. After completing the loading of monomers, the dispersion was maintained at 80 ° C for 15 minutes, cooled to 25 ° C and filtered to remove any clot. The filtered dispersion had a pH of 3.0, a content of 21.9% solids and an average particle size of 220 nm.

Example 8: A core was prepared as follows: a round-bottom, four-necked flask, with a capacity of 5 liters, was equipped with a paddle stirrer, thermometer, nitrogen inlet and reflux condenser. Deionized water, 1760 grams, was added to the kettle and heated to 86 ° C under a nitrogen atmosphere. An emulsion of monomers (EM) was prepared by mixing 720 grams of deionized water, 6.85 grams of sodium dodecylbenzenesulfonate (SDS, 23%), 10.0 grams of methacrylic acid and 780.0 grams of methyl methacrylate. From this MS, 164 grams were removed and placed separately. To the remaining MS were added 15.0 grams of SDS (23%) and 510 grams of methacrylic acid. With the copper water at 86 ° C, a mixture of 160 grams of deionized water and 1.75 grams of SDS (23%) and 10.0 grams of Plurafac® B-25-5, followed by the EM removed from the initial EM and then followed by the addition of a mixture of 5.5 grams of sodium persulfate in 40 grams of deionized water, were added to the copper. The contents of the copper were stirred for 15 minutes. The remaining MS was then fed to the pan over a period of two hours, at 85 ° C. After completing the loading of monomers, the dispersion was maintained at 85 ° C for 15 minutes, cooled to 25 ° C and filtered to remove any clot. The filtered dispersion had a pH of 2.9, a content of 31.9% solids and an average particle size of 349 nm.

Example 9; A core was prepared as follows: a round-bottom, four-neck, 5-liter capacity flask was equipped with a paddle stirrer, thermometer, nitrogen inlet and reflux condenser. Deionized water, 1760 grams, was added to the kettle and heated to 80 ° C under a nitrogen atmosphere. An emulsion of monomers (EM) was prepared by mixing 720 grams of deionized water, 5.25 grams of the surfactant Disponil® Fes-993, 10.0 grams of methacrylic acid and 780 grams of methyl methacrylate. From this MS, 164 grams were removed and placed separately. To the remaining MS were added 11.5 grams of Disponil® Fes-993 and 510 grams of methacrylic acid. With the copper water at 86 ° C, a mixture of 160 grams of deionized water, 0.4 grams of Disponil® Fes-993 and 20.5 grams of Silwet® L-7001 (Silwet is a trademark of Witco), followed by MS Removed from the initial ME, and then followed by a mixture of 5.5 grams of sodium persulfate in 40 grams of deionized water, were added to the copper. The contents of the copper were stirred for 15 minutes. The remaining MS was then fed to the pan over a period of two hours, at 85 ° C. After completing the loading of monomers, the dispersion was maintained at 85 ° C for 15 minutes, cooled to 25 ° C and filtered to remove any clot. The filtered dispersion had a pH of 2.8, a content of 31.6% solids and an average particle size of 401 nm.

Example 10: A core was prepared as follows: a 5-liter, four-necked round bottom flask was equipped with a paddle stirrer, thermometer, nitrogen inlet and reflux condenser. Deionized water, 1700 grams, was added to the kettle and heated to 80 ° C under a nitrogen atmosphere. An emulsion of monomers (EM) was prepared by mixing 335 grams of deionized water, 1.0 gram of Abex® CO-436, 4.5 grams of methacrylic acid and 364.5 grams of methyl methacrylate. From this MS, 82 grams were removed and placed separately. To the remaining MS were added 2.80 grams of Abex CO-436 and 241 grams of methacrylic acid. With the copper water at 80 ° C, the MS removed from the initial EM, followed by a mixture of 2.75 grams of ammonium persulfate in 15 grams of deionized water, was added to the copper. The contents of the copper were stirred for 15 minutes. The remaining MS was then fed to the kettle over a period of two hours, at 80 ° C. After completing the loading of monomers, the dispersion was maintained at 80 ° C for 15 minutes, cooled to 25 ° C and filtered to remove any clot. The filtered dispersion had a pH of 3.0, a content of 22.2% solids and an average particle size of 328 nm.

Example 11; A core was prepared as follows: a round-bottom, four-neck, 5-liter capacity flask was equipped with a paddle stirrer, thermometer, nitrogen inlet and reflux condenser. Deionized water, 1760 grams, was added to the kettle and heated to 86 ° C under a nitrogen atmosphere. An emulsion of monomers (EM) was prepared by mixing 720 grams of deionized water, 6.8 grams of sodium dodecylbenzenesulfonate (SDS, 23%), 10.0 grams of methacrylic acid and 780.0 grams of methyl methacrylate. From this MS, 164 grams were removed and placed separately. To the remaining MS were added 51.50 grams of SDS (23%) and 510 grams of methacrylic acid. With the copper water at 86 ° C, a mixture of 160 grams of deionized water, 25.0 grams of SDS and 20.5 grams of Plurafac® B-25-5, followed by the EM removed from the initial EM and then followed by the addition of a mixture of 5.5 grams of sodium persulfate in 40 grams of deionized water were added to the copper. The contents of the copper were stirred for 15 minutes. The remaining MS was then fed to the pan over a period of two hours, at 85 ° C. After completing the loading of monomers, the dispersion was maintained at 85 ° C for 15 minutes, cooled to 25 ° C and filtered to remove any clot. The filtered dispersion had a pH of 3.0, a content of 31.6% solids and an average particle size of 94 nm.

Example 12; A core was prepared as follows: a round-bottom, four-neck, 5-liter capacity flask was equipped with a paddle stirrer, thermometer, nitrogen inlet and reflux condenser. Deionized water, 1760 grams, was added to the kettle and heated to 86 ° C under a nitrogen atmosphere. An emulsion of monomers (EM) was prepared by mixing 720 grams of deionized water, 6.8 grams of sodium dodecylbenzenesulfonate (SDS, 23%), 10.0 grams of methacrylic acid and 780.0 grams of methyl methacrylate. From this MS, 164 grams were removed and placed separately. To the remaining MS were added 51.5 grams of SDS and 510 grams of methacrylic acid. With the copper water at 86 ° C, a mixture of 160 grams of deionized water and 25.0 grams of SDS (23%) and 20.5 grams of Silwet® L-7210, followed by the EM removed from the initial EM and then followed by the addition of a mixture of 5.5 grams of sodium persulfate in 40 grams of deionized water was added to the copper. The contents of the copper were stirred for 15 minutes. The remaining MS was then fed to the pan over a period of two hours, at 85 ° C. After completing the loading of monomers, the dispersion was maintained at 85 ° C for 15 minutes, cooled to 25 ° C and filtered to remove any clot. The filtered dispersion had a pH of 2.9, a content of 31.5% solids and an average particle size of 81 nm.

Example 13; A core was prepared as follows: a round-bottom, four-neck, 5-liter capacity flask was equipped with a paddle stirrer, thermometer, nitrogen inlet and reflux condenser. Deionized water, 1760 grams, was added to the kettle and heated to 86 ° C under a nitrogen atmosphere. An emulsion of monomers (EM) was prepared by mixing 720 grams of deionized water, 6.65 grams of sodium dodecyl-sulfonate (SDS, 23%), 10.0 grams of methacrylic acid and 780.0 grams of methyl methacrylate. From this MS, 164 grams were removed and placed separately. To the remaining MS were added 62.6 grams of SDS / 23%) and 510 grams of methacrylic acid. With the copper water at 86 ° C, a mixture of 160 grams of deionized water and 20.2 grams of SDS (23%), followed by the EM removed from the initial EM and then followed by the addition of a mixture of 5.5 grams of Sodium persulfate in 40 grams of de-ionized water, were added to the copper. The reaction mixture was stirred for 15 minutes. The remaining MS was then fed to the pan over a period of two hours, at 85 ° C. After completing the loading of monomers, the dispersion was maintained at 85 ° C for 15 minutes, cooled to 25 ° C and filtered to remove any clot. The filtered dispersion had a pH of 3.0, a content of 30.6% solids and an average particle size of 91 nm.

Example 14: A core was prepared as follows: a 5-liter, four-necked round bottom flask was equipped with a paddle stirrer, thermometer, nitrogen inlet and reflux condenser. Deionized water, 2260 grams, was added to the kettle and heated to 86 ° C under a nitrogen atmosphere. An emulsion of monomers (EM) was prepared by mixing 720 grams of deionized water, 2.70 grams of Abex® CO-436, 10.0 grams of methacrylic acid and 780.0 grams of methyl methacrylate. From this MS, 164 grams were removed and placed separately. To the remaining MS were added 23.0 grams of Abex CO-436 and 510 grams of methacrylic acid. With the copper water at 86 ° C, a mixture of 160 grams of deionized water and 8.0 grams of Abex® CO-436, followed by the EM removed from the initial EM, and then followed by a mixture of 2.76 grams of persulfate Ammonium in 40 grams of deionized water was added to the copper. The contents of the copper were stirred for 15 minutes. The remaining MS was then fed to the pan over a period of two hours, at 85 ° C. After completing the loading of monomers, the dispersion was maintained at 85 ° C for 15 minutes, cooled to 25 ° C and filtered to remove any clot. The filtered dispersion had a pH of 2.8, a content of 28.7% solids and an average particle size of 808 nm.

Example 15: A core was prepared as follows: a 5-liter, four-necked round bottom flask was equipped with a paddle stirrer, thermometer, nitrogen inlet and reflux condenser. Deionized water, 1760 grams, was added to the kettle and heated to 86 ° C under a nitrogen atmosphere. An emulsion of monomers (EM) was prepared by mixing 720 grams of deionized water, 17.2 grams of Abex® CO-436, 520.0 grams of methacrylic acid and 780.0 grams of methyl methacrylate. With the copper water at 86 ° C, a mixture of 160 grams of deionized water and 3.0 grams of Abex® CO-436, followed by a mixture of 5.5 grams of sodium persulfate in 40 grams of deionized water, were added to the copper. . The MS is then fed to the kettle for a period of two hours at 85 ° C. After completing the loading of monomers, the dispersion was maintained at 85 ° C for 15 minutes, cooled to 25 ° C and filtered to remove any clot. The filtered dispersion had a pH of 2.8, a content of 30.7.2% solids and an average particle size of 87 nm.

Example 16: A core was prepared as follows: a 5-liter, four-necked round bottom flask was equipped with a paddle stirrer, thermometer, nitrogen inlet and reflux condenser. Deionized water, 1760 grams, was added to the kettle and heated to 86 ° C under a nitrogen atmosphere. An emulsion of monomers (EM) was prepared by mixing 720 grams of deionized water, 2.7 grams of Abex® CO-436, 10.0 grams of methacrylic acid and 780 grams of methyl methacrylate. From this MS, 164 grams were removed and placed separately. To the remaining MS were added 14.5 grams of Abex CO-436 and 510 grams of methacrylic acid. With the copper water at 86 ° C, a mixture of 160 grams of deionized water and 3.0 grams of Abex® CO-436, followed by the EM removed from the initial EM, and then followed by a mixture of 5.5 grams of persulfate sodium in 40 grams of deionized water, were added to the copper. The contents of the copper were stirred for 15 minutes. The remaining MS was then fed to the pan over a period of two hours, at 85 ° C. After completing the loading of monomers, the dispersion was maintained at 85 ° C for 15 minutes, cooled to 25 ° C and filtered to remove any clot. The filtered dispersion had a pH of 2.8, a content of 31.3% solids and an average particle size of 118 nm.

The dry bulk density, as used herein and in the appended claims, was determined in accordance with the following procedure. To a 50 milliliter ("ml") centrifuge tube, 6.3 grams of polymer solids were added. Deionized water was added to the centrifuge tube to supply a total of 35 grams ("g") of material in the centrifuge tube, corresponding to 28 weight percent of the polymer solids. The tube was placed in a centrifuge that rotated at 18,000 revolutions per minute for 120 minutes. The supernatant was decanted and weighed. The dry density was then determined by the following equations:c.

Dry Density =% POLY x d % POLI = 1 -% H20 V H20 (VT - S H20) x FR - VP% H20 = V H20 + VP (VT - S H20) x FR VH20 = (VT -SH20) X FR - VP VP + VH20 = (VT "SH20) x FR VP + VH20 VP + VH20 FR Vp + VH2 = + IH20 HARD PACKAGE VP + VH20 HARD PACKAGE = Vt - SH20 = FR where: ^ = total weight in the tube = 35 grams VH20 = volume of water inside the particles I jj20 = interstitial volume of the water d = polymer density = 1.084 g / cc measured Vp = volume of the polymer (6.3 g / l. 084 g / cc = 5.81 cc) V ^ = total volume in the tube = 35 g - 6.3 g of solids = 28.7 g or cc of water + 5.81 cc of polymer = 34.51 cc Sjj20 = volume of the supernatant = weight of supernatant% H20 = percent of particles in water% PO I = Percent of the polymer in the particles FR = packing constant, which is a correction that corresponds to the fraction of solids in volume in the hard package. The following constant values of the package are used, based on the particle size of the polymer sample: Particle Size Interval (nm) FR < 275 0.611 275-500 0.624 501-750 0.638 751-1300 0.645 The values of the packing constants used are based on the density determinations (as described above) for uninflated polymer particles, such that the VJJ Q is zero. The packing constant, FR, is defined as: VP + VH20 VP + VH20 Vp FR VP + VH20 + IH20 HARD PACKAGE HARD PACKAGE Vp = polymer volume (6.3 g / 1.084 / cc = 5.81 cc) IH20 = water interstitial volume 0 (Wt - Sy2o - 6.3 g) / l.O g / cc Wrp = total weight in the tube = 35.0 grams. SH20 = Weight of the supernatant.

Using the above expression, the packing constants were determined for several samples of the polymer, having average particle sizes in the approximate range of 200 nm to 1275 nm.

Sample # P.S. (nm) SH20 Vp -H20 P + IH20 FR 1 213 25.0 5.81 3.70 9.51 0.611 2 440 25.2 5.81 3.50 9.31 0.624 3 650 25.4 5.81 3.30 9.11 0.638 4 1275 25.5 5.81 3.20 9.01 0.645 All particle sizes presented here were measured using a Brookhaven BI-90 Particle Meter, and presented as an average particle size.

Example 17: A round-bottom, four-necked flask, with a capacity of 5 liters, was equipped with a paddle stirrer, thermometer, nitrogen inlet and reflux condenser. Deionized water, 1700 grams, was added to the kettle and heated to 86 ° C under a nitrogen atmosphere. To the water of a heated pellet, 3.8 grams of sodium persulfate, dissolved in 30 grams of deionized water, were added. This was followed immediately by 190.5 grams of the core prepared in Example 1. A monomer emulsion (MS I) was prepared by mixing 50 grams of deionized water, 3.0 grams of SDS (23%), 10.8 grams of butyl methacrylate, 106.8 grams of methyl methacrylate and 2.4 grams of methacrylic acid and added to the copper at a rate of _4.5 grams / minute, at a temperature of 80 ° C. Upon completion of MS I, a second emulsion of monomers (ME II) was prepared by mixing 190 grams of deionized water, 3.8 grams of SDS (23%) and 720 grams of styrene. From this ME II, 137 grams were removed and placed separately. The initial portion of EM II was added to the kettle at a rate of 25 grams / minute and a mixture of 1.9 grams of sodium persulfate, dissolved in 75 grams of deionized water, was co-fed to the reactor at a rate of 2.5 grams. /minute. The temperature of the reaction mixture was allowed to increase to 92 ° C. Upon completion of EM II and co-charges, a mixture of 8 grams of 4-hydroxy TEMPO and 8 grams of deionized water were added to the kettle and the batch was cooled to 85 ° C. When the reaction mixture reached 85 ° C, the portion held back from the EM II (137 grams) was added to the reactor, followed by the addition of 42 grams of ammonium hydroxide. The reaction mixture was maintained for 5 minutes at 85 ° C. After holding for 5 minutes, a mixture of 0.95 grams of sodium persulfate dissolved in 20 grams of deionized water was added to the kettle. The reaction mixture was maintained for 30 minutes at 85 ° C and then cooled to room temperature and filtered to remove any formed coagulum. The final latex had a solids content of 27.5%, a pH of 10.0 and a particle size of 404 nm. An acid titration showed good encapsulation of the core with only 4.0% of the titratable core acid. The dry density of this polymer was determined to be 0.6189 g / cc.

Example 18; A round-bottom, four-necked, 5-liter flask was equipped with a paddle stirrer, thermometer, nitrogen inlet and reflux condenser. Deionized water, 1700 grams, was added to the kettle and heated to 86 ° C under a nitrogen atmosphere. To the water of a heated pellet, 3.8 grams of sodium persulfate, dissolved in 30 grams of deionized water, were added. This was immediately followed by 191 grams of the core prepared in Example 2. An emulsion of monomers (EM I) was prepared by mixing 50 grams of deionized water, 3.0 grams of SDS (23%), 10.8 grams of butyl methacrylate, 106.8 grams of methyl methacrylate and 2.4 grams of methacrylic acid and added to the kettle at a rate of 4.5 grams / minute, at a temperature of 80 ° C. Upon completion of MS I, a second emulsion of monomers (ME II) was prepared by mixing 190 grams of deionized water, 3.8 grams of SDS (23%) and 720 grams of styrene. Of this ME II, 91.4 grams were removed and placed separately. The initial portion of EM II was added to the kettle at a rate of 25 grams / minute and a mixture of 1.9 grams of sodium persulfate, dissolved in 75 grams of deionized water, was co-fed to the reactor at a rate of 2.5 grams. /minute. The temperature of the reaction mixture was allowed to increase to 92 ° C. Upon completion of the EM II and co-fillers, a mixture of 8 grams of 4-hydroxy TEMPO and 8 grams of deionized water were added to the kettle and the batch was cooled to 85 ° C. When the reaction mixture reached 85 ° C, the portion held back from the EM II (91.4 grams) was added to the reactor, followed by the addition of 42 grams of ammonium hydroxide. The reaction mixture was maintained for 5 minutes at 85 ° C. After holding for 5 minutes, a mixture of 0.95 grams of sodium persulfate dissolved in 20 grams of deionized water was added to the kettle. The reaction mixture was maintained for 30 minutes at 85 ° C and then cooled to room temperature and filtered to remove any formed coagulum. The final latex had a solids content of 27.4%, a pH of 9.9 and a particle size of 440 nm. An acid titration showed good core encapsulation with only 2.0% titratable core acid. The dry density of this polymer was determined to be 0.6077 g / cc.

Example 19; A round-bottom, four-necked, 5-liter flask was equipped with a paddle stirrer, thermometer, nitrogen inlet and reflux condenser. Deionized water, 1700 grams, was added to the kettle and heated to 86 ° C under a nitrogen atmosphere. To the water of a heated pellet, 3.8 grams of sodium persulfate, dissolved in 30 grams of deionized water, were added. This was immediately followed by 188.5 grams of the core prepared in Example 3. An emulsion of monomers (EM I) was prepared by mixing 50 grams of deionized water, 3.0 grams of SDS, 10.8 grams of butyl methacrylate, 106.8 grams of methyl methacrylate. and 2.4 grams of methacrylic acid and added to the kettle at a rate of 4.5 grams / minute, at a temperature of 80 ° C. Upon completion of the EM I, a second monomer emulsion (ME II) was prepared by mixing 190 grams of deionized water, 3.8 grams of SDS and 720 grams of styrene. Of this ME II, 91.4 grams were removed and placed separately. The initial portion of EM II was added to the kettle at a rate of 25 grams / minute and a mixture of 1.9 grams of sodium persulfate, dissolved in 75 grams of deionized water, was co-fed to the reactor at a rate of 2.5 grams. / minute The temperature of the reaction mixture was allowed to increase to 92 ° C. Upon completion of the EM II and co-loads a mixture of 8 grams of 4-hydroxy TEMPO 8 grams of deionized water were added to the kettle and the batch was cooled to 85 ° C.

When the contents of the reactor reached 85 ° C, the portion held behind the MS II (91.4 grams) was added to the reactor, followed by the addition of 42 grams of ammonium hydroxide. The reaction mixture was maintained for 5 minutes at 85 ° C. After holding for 5 minutes, a mixture of 0.95 grams of sodium persulfate dissolved in 20 grams of deionized water was added to the pan. The reaction mixture was maintained for 30 minutes at 85 ° C and then cooled to room temperature and filtered to remove any formed coagulum. The final latex had a solids content of 27.3%, a pH of 10.2 and a particle size of 370 nm. An acid titration showed good encapsulation of the core with only 2.5% of the titratable core acid. The dry density of this polymer was determined to be 0.6466 g / cc.

Example 20: A 5-liter, four-necked round bottom flask was equipped with a paddle stirrer, thermometer, nitrogen inlet and reflux condenser. Deionized water, 1400 grams, was added to the kettle and heated to 86 ° C under a nitrogen atmosphere. To the water of a heated pellet, 3.8 grams of sodium persulfate, dissolved in 30 grams of deionized water, were added. This was immediately followed by 271.5 grams of the core prepared in Example 4. An emulsion of monomers (EM I) was prepared by mixing 50 grams of deionized water, 3.0 grams of SDS (23%), 10.8 grams of butyl methacrylate, 106.8 grams of methyl methacrylate and 2.4 grams of methacrylic acid and added to the kettle at a rate of 4.5 grams / minute, at a temperature of 80 ° C. Upon completion of MS I, a second emulsion of monomers (ME II) was prepared by mixing 190 grams of deionized water, 3.8 grams of SDS (23%) and 720 grams of styrene. From this ME II, 137 grams were removed and placed separately. The initial portion of EM II was added to the kettle at a rate of 25 grams / minute and a mixture of 1.9 grams of sodium persulfate, dissolved in 75 grams of deionized water, was co-fed to the reactor at a rate of 2.5 grams. /minute. The temperature of the reaction mixture was allowed to increase to 92 ° C. Upon completion of the EM II and co-loads, a mixture of 8 grams of TEMPO-hydroxy-8 grams of deionized water was added to the kettle and the batch was cooled to 85 ° C. When the reaction mixture reached 85 ° C, the portion held back from the EM II (137 grams) was added to the reactor, followed by the addition of 42 grams of ammonium hydroxide. The reaction mixture was maintained for 5 minutes at 85 ° C. After holding for 5 minutes, a mixture of 0.95 grams of sodium persulfate dissolved in 20 grams of deionized water was added to the kettle. The reaction mixture was maintained for 30 minutes at 85 ° C and then cooled to room temperature and filtered to remove any formed coagulum. The final latex had a solids content of 29.5%, a pH of 10.2 and a particle size of 525 nm. An acid titration showed good encapsulation of the core with only 5.0% of the titratable core acid. The dry density of this polymer was determined to be 0.5735 g / cc.

Example 21: A 5-liter, four-necked round bottom flask was equipped with a paddle stirrer, thermometer, nitrogen inlet and reflux condenser. Deionized water, 1700 grams, was added to the kettle and heated to 86 ° C under a nitrogen atmosphere. To the water of a heated pellet, 3.8 grams of sodium persulfate, dissolved in 30 grams of deionized water, were added. This was followed immediately by 189.9 grams of the core prepared in Example 5. An emulsion of monomers (EM I) was prepared by mixing 50 grams of deionized water, 3.0 grams of SDS, 10.8 grams of butyl methacrylate, 106.8 grams of methyl methacrylate. and 2.4 grams of methacrylic acid and added to the kettle at a rate of 4.5 grams / minute, at a temperature of 80 ° C. Upon completion of the EM I, a second monomer emulsion (ME II) was prepared by mixing 190 grams of deionized water, 3.8 grams of SDS and 720 grams of styrene. From this ME II, 137 grams were removed and placed separately. The initial portion of the EM II was added to the kettle at a rate of 25 grams / minute and a mixture of 1.9 grams of sodium persulfate, dissolved in 75 grams of deionized water, was co-fed to the reactor at a rate of 2.5 grams / minute. The temperature of the reaction mixture was allowed to increase to 92 ° C. Upon completion of the EM II and co-fillers, a mixture of 8 grams of 4-hydroxy TEMPO and 8 grams of deionized water were added to the kettle and the batch was cooled to 85 ° C. When the temperature of the copper reached 85 ° C, the portion held back from the EM II (137 grams) was added to the reactor, followed by the addition of 42 grams of ammonium hydroxide. The reaction mixture was maintained for 5 minutes at 85 ° C. After holding for 5 minutes, a mixture of 0.95 grams of sodium persulfate dissolved in 20 grams of deionized water was added to the pan. The reaction mixture was maintained for 30 minutes at 85 ° C and then cooled to room temperature and filtered to remove any formed coagulum. The final latex had a solids content of 27.3%, a pH of 10.2 and a particle size of 577 nm. An acid titration showed good encapsulation of the core with only 5.0% of the titratable core acid. The dry density of this polymer was determined to be 0.5605 g / cc.

Example 22: A 5-liter four-necked round bottom flask was equipped with a paddle stirrer, thermometer, nitrogen inlet and reflux condenser. Deionized water, 1700 grams, was added to the kettle and heated to 86 ° C under a nitrogen atmosphere. To the water of a heated pellet, 3.8 grams of sodium persulfate, dissolved in 30 grams of deionized water, were added. This was immediately followed by 279.9 grams of the core prepared in Example 6. A monomer emulsion (MS I) was prepared by mixing 50 grams of deionized water, 3.0 grams of SDS, 10.8 grams of butyl methacrylate, 106.8 grams of methyl methacrylate. and 2.4 grams of methacrylic acid and added to the kettle at a rate of 4.5 grams / minute, at a temperature of 80 ° C. Upon completion of the EM I, a second monomer emulsion (ME II) was prepared by mixing 190 grams of deionized water, 3.8 grams of SDS and 720 grams of styrene. Of this ME II, 91.4 grams were removed and placed separately. The initial portion of the EM II was added to the kettle at a rate of 25 grams / minute and a mixture of 1.9 grams of sodium persulfate, dissolved in 75 grams of de-ionized water, was co-fed to the reactor at a rate of 2.5 grams / minute. The temperature of the reaction mixture was allowed to increase to 92 ° C. Upon completion of the EM II and co-loads a mixture of 8 grams of 4-hydroxy TEMPO and 8 grams of deionized water were added to the kettle and the batch was cooled to 85 ° C. When the reaction mixture reached 85 ° C, the portion held back from the EM II (91.4 grams) was added to the reactor, followed by the addition of 42 grams of ammonium hydroxide. The reaction mixture was maintained for 5 minutes at 85 ° C. After holding for 5 minutes, a mixture of 0.95 grams of sodium persulfate dissolved in 20 grams of deionized water was added to the kettle. The reaction mixture was maintained for 30 minutes at 85 ° C and then cooled to room temperature and filtered to remove any formed coagulum. The final latex had a solids content of 26.6%, a pH of 10.1 and a particle size of 515 nm. An acid titration showed good encapsulation of the core with only 2.5% of the titratable core acid. The dry density of this polymer was determined to be 0.5979 g / cc.

Example 23: A 5-liter, four-necked round bottom flask was equipped with a paddle stirrer, thermometer, nitrogen inlet and reflux condenser. Deionized water, 1700 grams, was added to the kettle and heated to 86 ° C under a nitrogen atmosphere. To the water of a heated pellet, 3.8 grams of sodium persulfate, dissolved in 30 grams of deionized water, were added. This was followed immediately by 274.0 grams of the core prepared in Example 7. An emulsion of monomers (EM I) was prepared by mixing 50 grams of deionized water, 3.0 grams of SDS (23%), 10.8 grams of butyl methacrylate, 106.8 grams of methyl methacrylate and 2.4 grams of methacrylic acid and added to the kettle at a rate of 4.5 grams / minute, at a temperature of 80 ° C. Upon completion of the EM I, a second monomer emulsion (ME II) was prepared by mixing 190 grams of deionized water, 3.8 grams of SDS and 720 grams of styrene. Of this ME II, 91.4 grams were removed and placed separately. The initial portion of EM II was added to the kettle at a rate of 25 grams / minute and a mixture of 1.9 grams of sodium persulfate, dissolved in 75 grams of deionized water, was co-fed to the reactor at a rate of 2.5 grams. /minute. The temperature of the reaction mixture was allowed to increase to 92 ° C. Upon completion of EM II and co-charges, a mixture of 8 grams of 4-hydroxy TEMPO and 8 grams of deionized water were added to the kettle and the batch was cooled to 85 ° C. When the temperature of the copper reached 85 ° C, the portion held back from the EM II (91.4 grams) was added to the reactor, followed by the addition of 42 grams of ammonium hydroxide. The reaction mixture was maintained for 5 minutes at 85 ° C. After holding for 5 minutes, a mixture of 0.95 grams of sodium persulfate dissolved in 20 grams of deionized water was added to the pan. The reaction mixture was maintained for 30 minutes at 85 ° C and then cooled to room temperature and filtered to remove any formed coagulum. The final latex had a solids content of 26.6%, a pH of 10.3 and a particle size of 650 nm. An acid titration showed good core encapsulation with only 5.4% titratable core acid. The dry density of this polymer was determined to be 0.5804 g / cc.

Example 24: A 5-liter, four-necked round bottom flask was equipped with a paddle stirrer, thermometer, nitrogen inlet and reflux condenser. Deionized water, 2000 grams, was added to the kettle and heated to 86 ° C under a nitrogen atmosphere. To the water of a heated pellet, 3.8 grams of sodium persulfate, dissolved in 30 grams of deionized water, were added. This was immediately followed by 188.0 grams of the core prepared in Example 8. A monomer emulsion (EM I) was prepared by mixing 50 grams of deionized water, 3.0 grams of SDS, 12.0 grams of butyl methacrylate, 105.6 grams of methyl methacrylate. and 2.4 grams of methacrylic acid and added to the copper at a rate of 3.0 grams / minute, at a temperature of 80 ° C. Upon completion of EM I, a second monomer emulsion (ME II) was prepared by mixing 160 grams of deionized water, 3.2 grams of SDS and 600 grams of styrene and 1.5 grams of allyl methacrylate. From this ME II, 114 grams were removed and placed separately. The initial portion of EM II was added to the kettle at a rate of 12.5 grams / minute and a mixture of 1.9 grams of sodium persulfate, dissolved in 75 grams of deionized water, was co-fed to the reactor at a rate of 2.5 grams / minute. . After 10 minutes, the EM II regimen was increased to 25 grams / minute. The temperature of the reaction mixture was allowed to increase to 92 ° C. Upon completion of the EM II and co-charges, a mixture of 8 grams of 4-hydroxy TEMPO and 8 grams of deionized water were added to the kettle and the batch was cooled to 85 ° C. When the reaction mixture reached 85 ° C, the portion held back from the EM II (114 grams) was added to the reactor, followed by the addition of 38 grams of ammonium hydroxide. The reaction mixture was maintained for 5 minutes at 85 ° C. After holding for 5 minutes, a mixture of 0.95 grams of sodium persulfate dissolved in 20 grams of deionized water was added to the kettle. The copper was kept for 30 minutes at 85 ° C and then cooled to room temperature and filtered to remove any formed coagulum. The final latex had a solids content of 22.6%, a pH of 10.4 and a particle size of 1235 nm. An acid titration showed good core encapsulation with only 2.0% titratable core acid. The dry density of this polymer was determined to be 0.4670 g / cc.

Example 25: A 5-liter, four-necked round bottom flask was equipped with a paddle stirrer, thermometer, nitrogen inlet and reflux condenser. Deionized water, 2000 grams, was added to the kettle and heated to 86 ° C under a nitrogen atmosphere. To the water of a heated pellet, 3.8 grams of sodium persulfate, dissolved in 30 grams of deionized water, were added. This was immediately followed by 188.9 grams of the core prepared in Example 9. An emulsion of monomers (EM I) was prepared by mixing 50 grams of deionized water, 3.0 grams of SDS, 12.0 grams of butyl methacrylate, 105.6 grams of methyl methacrylate. and 2.4 grams of methacrylic acid and added to the copper at a rate of 3.0 grams / minute, at a temperature of 80 CC. Upon completion of MS I, a second emulsion of monomers (ME II) was prepared by mixing 160 grams of deionized water, 3.2 grams of SDS and 600 grams of styrene, 3.0 grams of flaxseed oil fatty acid and 1.5 grams of allyl methacrylate. . From this ME II, 114 grams were removed and placed separately. The initial portion of the EM II was added to the kettle at a rate of 12.5 grams / minute and a mixture of 1.9 grams of sodium persulfate, dissolved in 75 grams of deionized water, was co-fed to the reactor at a rate of 2.5 grams. /minute. After 10 minutes, the EM II regimen was increased to 25 grams / minute. The temperature of the reaction mixture was allowed to increase to 92 ° C. Upon completion of EM II and co-charges, a mixture of 8 grams of 4-hydroxy TEMPO and 8 grams of deionized water were added to the kettle and the batch was cooled to 85 ° C. When the reaction mixture reached 85 ° C, the portion held behind the EM II (114 grams) was added to the reactor, followed by the addition of 38 grams of ammonium hydroxide. The reaction mixture was maintained for 5 minutes at 85 ° C. After holding for 5 minutes, a mixture of 0.95 grams of sodium persulfate dissolved in 20 grams of deionized water was added to the kettle. The batch was kept for 30 minutes at 85 ° C and then cooled to room temperature and filtered to remove any clot formed. The final latex had a solids content of 22.4%, a pH of 10.3 and a particle size of 1275 nm. An acid titration showed good encapsulation of the core with only 4.5% of the titratable core acid. The dry density of this polymer was determined to be 0.4357 g / cc.

Example 26: A 5-liter, four-necked round bottom flask was equipped with a paddle stirrer, thermometer, nitrogen inlet and reflux condenser. Deionized water, 2000 grams, was added to the kettle and heated to 86 ° C under a nitrogen atmosphere. To the water of a heated pellet, 3.8 grams of sodium persulfate, dissolved in 30 grams of deionized water, were added. This was immediately followed by 270.3 grams of the core prepared in Example 10. An emulsion of monomers (EM I) was prepared by mixing 50 grams of deionized water, 3.0 grams of SDS, 12.0 grams of butyl methacrylate, 105.6 grams of methyl methacrylate. and 2.4 grams of methacrylic acid and added to the copper at a rate of 3.0 grams / minute, at a temperature of 80 ° C. Upon completion of EM I, a second monomer emulsion (ME II) was prepared by mixing 160 grams of deionized water, 3.2 grams of SDS and 600 grams of styrene and 3.0 grams of divinyl-benzene. From this ME II, 114 grams were removed and placed separately. The initial portion of the EM II was added to the kettle at a rate of 12.5 grams / minute and a mixture of 1.9 grams of sodium persulfate, dissolved in 75 grams of deionized water, was co-fed to the reactor at a rate of 2.5 grams. /minute. After 10 minutes, the EM II regimen was increased to 25 grams / minute. The temperature of the reaction mixture was allowed to increase to 92 ° C. Upon completion of EM II and co-charges, a mixture of 8 grams of 4-hydroxy TEMPO and 8 grams of deionized water were added to the kettle and the batch was cooled to 85 ° C. When the temperature of the copper reached 85 ° C, the portion held behind the EM II (114 grams) was added to the reactor, followed by the addition of 38 grams of ammonium hydroxide. The reaction mixture was maintained for 5 minutes at 85 ° C. After holding for 5 minutes, a mixture of 0.95 grams of sodium persulfate dissolved in 20 grams of deionized water was added to the kettle. The reaction mixture was maintained for 30 minutes at 85 ° C and then cooled to room temperature and filtered to remove any formed coagulum. The final latex had a solids content of 22.1%, a pH of 10.0 and a particle size of 907 nm. An acid titration showed good core encapsulation with only 2.0% titratable core acid. The dry density of this polymer was determined to be 0.4648 g / cc.

Example 27: A 5-liter, four-necked round bottom flask was equipped with a paddle stirrer, thermometer, nitrogen inlet and reflux condenser. Deionized water, 2200 grams, was added to the kettle and heated to 86 ° C under a nitrogen atmosphere. To the water of a heated pellet, 3.8 grams of sodium persulfate, dissolved in 30 grams of deionized water, were added. This was immediately followed by 189.9 grams of the core prepared in Example 11. A monomer emulsion (MS I) was prepared by mixing 100 grams of deionized water, 6.0 grams of SDS, 21.6 grams of butyl methacrylate, 213.6 grams of methyl methacrylate. and 4.8 grams of methacrylic acid and added to the copper at a rate of 6.0 grams / minute, at a temperature of 80 ° C. Upon completion of MS I, a second emulsion of monomers (ME II) was prepared by mixing 190 grams of deionized water, 3.8 grams of SDS (23%) and 720 grams of styrene. From this EM II, 137 grams were removed and placed apart. The initial portion of EM II was added to the kettle at a rate of 12.5 grams / minute and a mixture of 1.9 grams of sodium persulfate, dissolved in 75 grams of deionized water, was co-fed to the reactor at a rate of 2.0 grams. /minute. After 10 minutes, the EM II regimen was increased to 25 grams / minute. The temperature of the reaction mixture was allowed to increase to 92 ° C. Upon completion of the EM II and co-loads a mixture of 8 grams of 4-hydroxy TEMPO and 8 grams of deionized water were added to the kettle and the batch was cooled to 85 ° C. When the reaction mixture reached 85 ° C, the portion held behind the MS II (137 grams) was added to the reactor, followed by the addition of 42 grams of ammonium hydroxide. The reaction mixture was maintained for 5 minutes at 85 ° C. After holding for 5 minutes, a mixture of 0.95 grams of sodium persulfate dissolved in 20 grams of deionized water was added to the kettle. The reaction mixture was maintained for 30 minutes at 85 ° C and then cooled to room temperature and filtered to remove any formed coagulum. The final latex had a solids content of 25.0%, a pH of 10.2 and a particle size of 176 nm. An acid titration showed good encapsulation of the core with only 4.5% of the titratable core acid. The dry density of this polymer was determined to be 0.6985 g / cc.

Example 28: A 5-liter, four-necked round bottom flask was equipped with a paddle stirrer, thermometer, nitrogen inlet and reflux condenser. Deionized water, 2200 grams, was added to the kettle and heated to 86 ° C under a nitrogen atmosphere. To the water of a heated pellet, 3.8 grams of sodium persulfate, dissolved in 30 grams of deionized water, were added. This was followed immediately by 190.5 grams of the core prepared in Example 12. An emulsion of monomers (MS I) was prepared by mixing 100 grams of deionized water, 6.0 grams of SDS, 21.6 grams of butyl methacrylate, 213.6 grams of methyl methacrylate. and 4.8 grams of methacrylic acid and added to the copper at a rate of 6.0 grams / minute, at a temperature of 80 ° C. Upon completion of the EM I, a second emulsion of monomers (ME II) was prepared by mixing 190 grams of deionized water, 3.8 grams of SDS and 720 grams of styrene. From this EM II, 91.4 grams were removed and placed separately. The initial portion of EM II was added to the kettle at a rate of 12.5 grams / minute and a mixture of 1.9 grams of sodium persulfate, dissolved in 75 grams of deionized water, was co-fed to the reactor at a rate of 2.0 grams. /minute. After 10 minutes, the EM II regimen was increased to 25 grams / minute. The temperature of the reaction mixture was allowed to increase to 92 ° C. Upon completion of the EM II and co-fillers, a mixture of 8 grams of 4-hydroxy TEMPO and 8 grams of deionized water were added to the kettle and the batch was cooled to 85 ° C. When the reaction mixture reached 85 ° C, the portion maintained behind the MS II (91.5 grams) was added to the reactor, followed by the addition of 42 grams of ammonium hydroxide. The reaction mixture was maintained for 5 minutes at 85 ° C. After holding for 5 minutes, a mixture of 0.95 grams of sodium persulfate dissolved in 20 grams of deionized water was added to the kettle. The reaction mixture was maintained for 30 minutes at 85 ° C and then cooled to room temperature and filtered to remove any formed coagulum. The final latex had a solids content of 26.0%, a pH of 10.2 and a particle size of 213 nm. An acid titration showed good encapsulation of the core with only 4.0% of the titratable core acid. The dry density of this polymer was determined to be 0.7631 g / cc.

Example 29: A 5-liter, four-necked round bottom flask was equipped with a paddle stirrer, thermometer, nitrogen inlet and reflux condenser. Deionized water, 2200 grams, was added to the kettle and heated to 86 ° C under a nitrogen atmosphere. To the water of a heated pellet, 3.8 grams of sodium persulfate, dissolved in 30 grams of deionized water, were added. This was immediately followed by 196.1 grams of the core prepared in Example 13. A monomer emulsion (MS I) was prepared by mixing 100 grams of deionized water, 6.0 grams of SDS, 21.6 grams of butyl methacrylate, 213.6 grams of methyl methacrylate. and 4.8 grams of methacrylic acid and added to the copper at a rate of 6.0 grams / minute, at a temperature of 80 ° C. Upon completion of the EM I, a second emulsion of monomers (ME II) was prepared by mixing 190 grams of deionized water, 3.8 grams of SDS, 720 grams of styrene and 3.6 grams of fatty acid of flaxseed oil. Of this ME II, 91.4 grams were removed and placed separately. The initial portion of EM II was added to the kettle at a rate of 12.5 grams / minute and a mixture of 1.9 grams of sodium persulfate, dissolved in 75 grams of deionized water, was co-fed to the reactor at a rate of 2.0 grams. /minute. After 10 minutes, the EM II regimen was increased to 25 grams / minute. The temperature of the reaction mixture was allowed to increase to 92 ° C. Upon completion of the EM II and co-loads a mixture of 8 grams of 4-hydroxy TEMPO and 8 grams of deionized water were added to the kettle and the batch was cooled to 85 ° C. When the reaction mixture reached 85 ° C, the portion held behind the MS II (91.4 grams) was added to the reactor, followed by the addition of 42 grams of ammonium hydroxide. The reaction mixture was maintained for 5 minutes at 85 ° C. After holding for 5 minutes, a mixture of 0.95 grams of sodium persulfate dissolved in 20 grams of deionized water was added to the kettle. The reaction mixture was maintained for 30 minutes at 85 ° C and then cooled to room temperature and filtered to remove any formed clot. The final latex had a solids content of 24.9%, a pH of 10.2 and a particle size of 284 nm. An acid titration showed good encapsulation of the core with only 5.0% of the titratable core acid. The dry density of this polymer was determined to be 0.6500 g / cc.

Example 30: A 5-liter, four-necked round bottom flask was equipped with a paddle stirrer, thermometer, nitrogen inlet and reflux condenser. Deionized water, 1620 grams, was added to the kettle and heated to 86 ° C under a nitrogen atmosphere. To the water of a heated pellet, 2.66 grams of sodium persulfate, dissolved in 21.0 grams of deionized water, were added. This was followed immediately by 146.3 grams of the core prepared in Example 14. A monomer emulsion (MS I) was prepared by mixing 70 grams of deionized water, 4.2 grams of SDS, 15.1 grams of butyl methacrylate, 149.2 grams of methyl methacrylate. and 3.36 grams of methacrylic acid and added to the copper at a rate of 4.0 grams / minute, at a temperature of 80 ° C. Upon completion of MS I, a second emulsion of monomers (ME II) was prepared by mixing 133 grams of deionized water, 2.7 grams of SDS and 504 grams of styrene. From this MS II, 64 grams were removed and placed separately. The initial portion of EM II was added to the copper at a rate of 8.8 grams / minute and a mixture of 1.3 grams of sodium persulfate, dissolved in 60 grams of deionized water, was co-fed to the reactor at a rate of 1.50 grams. /minute. After 10 minutes, the EM II regimen was increased to 17.5 grams / minute. The temperature of the reaction mixture was allowed to increase to 92 ° C. Upon completion of the EM II and co-loads a mixture of 5.6 grams of 4-hydroxy TEMPO and 5.6 grams of deionized water, it was added to the reaction mixture and the batch was cooled to 85 ° C. When the reaction mixture reached 85 ° C, the portion held behind the MS II (64.0 grams) was added to the reactor, followed by the addition of 26.6 grams of ammonium hydroxide. The reaction mixture was maintained for 5 minutes at 85 ° C. After holding for 5 minutes, a mixture of 0.67 grams of sodium persulfate dissolved in 14 grams of deionized water was added to the pan. The reaction mixture was maintained for 30 minutes at 85 ° C and then cooled to room temperature and filtered to remove any formed coagulum. The final latex had a solids content of 24.5%, a pH of 10.2 and a particle size of 196 nm. An acid titration showed good core encapsulation with only 2.0% titratable core acid. The dry density of this polymer was determined to be 0.7955 g / cc.

Example 31: A 5-liter, four-necked round bottom flask was equipped with a paddle stirrer, thermometer, nitrogen inlet and reflux condenser. Deionized water, 2000 grams, was added to the kettle and heated to 86 ° C under a nitrogen atmosphere. To the water of a heated pellet, 3.8 grams of sodium persulfate, dissolved in 30 grams of deionized water, were added. This was immediately followed by 195.4 grams of the core prepared in Example 15. An emulsion of monomers (EM I) was prepared by mixing 50 grams of deionized water, 3.0 grams of SDS, 10.8 grams of butyl methacrylate, 106.8 grams of methyl methacrylate. and 2.4 grams of methacrylic acid and added to the copper at a rate of 3.0 grams / minute, at a temperature of 80"C. At the completion of the EM I, a second emulsion of monomers (ME II) was prepared by mixing 190 grams of water deionized, 3.8 grams of SDS (23%) and 720 grams of styrene, from this EM II, 137 grams were removed and placed separately.The initial portion of the EM II was added to the kettle at a rate of 12.5 grams / minute and a mixture of 1.9 grams of sodium persulfate, dissolved in 75 grams of deionized water, was co-fed to the reactor at a rate of 2.0 grams / minute.After 10 minutes, the EM II regimen was increased to 25 grams / The temperature of the reaction mixture is p Hermitage increased to 92 ° C. Upon completion of the EM II and co-loads a mixture of 8 grams of 4-hydroxy TEMPO, and 8 grams of deionized water was added to the reaction mixture and the batch and cooled to 85 ° C. When the reaction mixture reached 85 ° C, the portion held behind the MS II (137 grams) was added to the reactor, followed by the addition of 42 grams of ammonium hydroxide. The reaction mixture was maintained for 5 minutes at 85 ° C. After holding for 5 minutes, a mixture of 0.95 grams of sodium persulfate dissolved in 20 grams of deionized water was added to the kettle. The reaction mixture was maintained for 30 minutes at 85 ° C and then cooled to room temperature and filtered to remove any formed coagulum. The final latex had a solids content of 25.2%, a pH of 10.0 and a particle size of 305 nm. An acid titration showed good encapsulation of the core with only 4.0% of the titratable core acid. The dry density of this polymer was determined to be 0.6690 g / cc.

Example 32: A 5-liter, four-necked round bottom flask was equipped with a paddle stirrer, thermometer, nitrogen inlet and reflux condenser. Deionized water, 1700 grams, was added to the kettle and heated to 86 ° C under a nitrogen atmosphere. To the water of a heated pellet, 3.8 grams of sodium persulfate, dissolved in 30 grams of deionized water, were added. This was immediately followed by 191.5 grams of the kernel prepared in the Example 16. A monomer emulsion (EM I) was prepared by mixing 50 grams of deionized water, 3.0 grams of SDS (23%), 10.8 grams of butyl methacrylate, 106.8 grams of methyl methacrylate and 2.4 grams of methacrylic acid and added to the copper at a rate of 3.0 grams / minute, at a temperature of 80 ° C. Upon completion of MS I, a second emulsion of monomers (ME II) was prepared by mixing 190 grams of deionized water, 3.8 grams of SDS (23%) and 720 grams of styrene. From this EM II, 137 grams were removed and placed apart. The initial portion of the EM II was added to the kettle at a rate of 12.5 grams / minute and a mixture of 1.9 grams of sodium persulfate, dissolved in 75 grams of deionized water, was co-fed to the reactor at a rate of 2.5 grams. /minute. After 10 minutes, the EM II regimen was increased to 25 grams / minute. The temperature of the reaction mixture was allowed to increase to 92 ° C. Upon completion of the EM II and co-charges, a mixture of 8 grams of 4-hydroxy TEMPO and 8 grams of deionized water were added to the copper and the batch was cooled to 85 ° C. When the reaction mixture reached 85 ° C, the portion held back from the EM II (137 grams) was added to the reactor, followed by the addition of 42 grams of ammonium hydroxide. The reaction mixture was maintained for 5 minutes at 85 ° C. After holding for 5 minutes, a mixture of 0.95 grams of sodium persulfate dissolved in 20 grams of deionized water was added to the kettle. The contents of the pellet were maintained for 30 minutes at 85 ° C and then cooled to room temperature and filtered to remove any formed clot. The final latex had a solids content of 27.4%, a pH of 10.2 and a particle size of 334 nm. An acid titration showed good encapsulation of the core with only 2.5% of the titratable core acid. The dry density of this polymer was determined to be 0.6445 g / cc. Example 33: (Comparative) A 5-liter, four-necked round bottom flask was equipped with a paddle stirrer, thermometer, nitrogen inlet and reflux condenser. Deionized water, 1700 grams, was added to the kettle and heated to 86 ° C under a nitrogen atmosphere. To the water of a heated pellet, 3.8 grams of sodium persulfate, dissolved in 30 grams of deionized water, were added. This was followed immediately by 199.8 grams of the core prepared in Example 1. An emulsion of monomers (MS I) was prepared by mixing 50 grams of deionized water, 3.0 grams of SDS (23%), 10.8 grams of butyl methacrylate, 106.8 grams of methyl methacrylate and 2.4 grams of methacrylic acid and added to the kettle at a rate of 4.5 grams / minute, at a temperature of 80 ° C. Upon completion of MS I, a second emulsion of monomers (ME II) was prepared by mixing 190 grams of deionized water, 3.8 grams of SDS (23%) and 720 grams of styrene. From this EM II, 137 grams were removed and placed apart. The initial portion of EM II was added to the kettle at a rate of 25.0 grams / minute and a mixture of 1.9 grams of sodium persulfate, dissolved in 75 grams of deionized water, was co-fed to the reactor at a rate of 2.5 grams. / minute The temperature of the batch was allowed to increase to 92 ° C. Upon completion of the EM II and co-charges, the batch was cooled to 85 ° C (no inhibitor added). When the temperature of the copper reached 85 ° C, the portion held back from the EM II (137 grams) was added to the reactor, followed by the addition of 42 grams of ammonium hydroxide. The temperature of the copper was maintained for 5 minutes at 85 ° C. After holding for 5 minutes, a mixture of 0.95 grams of sodium persulfate dissolved in 20 grams of deionized water was added to the pan. The contents of the pellet were maintained for 30 minutes at 85 ° C and then cooled to room temperature and filtered to remove any formed clot. The final latex had a solids content of 27.5%, a pH of 10.1 and a particle size of 320 nm. An acid titration showed good encapsulation of the core with only 4.0% of the titratable core acid. The dry density of this polymer was determined to be 0.7818 g / cc.

Example 34; (Comparative) A 5-liter, four-necked round bottom flask was equipped with a paddle stirrer, thermometer, nitrogen inlet and reflux condenser. Deionized water, 1700 grams, was added to the kettle and heated to 86 ° C under a nitrogen atmosphere. To the water of a heated pellet, 3.8 grams of sodium persulfate, dissolved in 30 grams of deionized water, were added. This was immediately followed by 1998.0 grams of the core prepared in Example 1. A monomer emulsion (MS I) was prepared by mixing 50 grams of deionized water, 3.0 grams of SDS (23%), 10.8 grams of butyl methacrylate, 106.8 grams of methyl methacrylate and 2.4 grams of methacrylic acid and added to the kettle at a rate of 4.5 grams / minute, at a temperature of 80 ° C. Upon completion of MS I, a second emulsion of monomers (ME II) was prepared by mixing 190 grams of deionized water, 3.8 grams of SDS (23%) and 720 grams of styrene. MS II was added to the kettle at a rate of 25.0. grams / minutes and a mixture of 1.9 grams of sodium persulfate, dissolved in 75 grams of deionized water was co-fed to the reactor at a rate of 2.5 grams / minute. The temperature of the batch was allowed to increase to 92 ° C. When 777 grams of EM II were added to the pan, 42 grams of ammonium hydroxide were added to the pan and EM II was continued. Upon completion of EM II and co-loads, the batch was maintained for 5 minutes at 92 ° C. After 5 minutes of retention, the batch was cooled to 85 ° C and a mixture of 0.95 grams of sodium persulfate, dissolved in 20 grams of deionized water, was added to the copper. The contents of the pellet were maintained for 30 minutes at 85 ° C and then cooled to room temperature and filtered to remove any formed clot. The final latex had a solids content of 27.7%, a pH of 10.1 and a particle size of 406 nm. An acid titration showed more titratable core acid (8.7%) compared to Example # 17. The dry density of this polymer was determined to be 0.6906 g / cc.

Example 35: (Comparative) A 5-liter, four-necked round bottom flask was equipped with a paddle stirrer, thermometer, nitrogen inlet and reflux condenser. Deionized water, 1700 grams, was added to the kettle and heated to 86 ° C under a nitrogen atmosphere. To the water of a heated pellet, 3.8 grams of sodium persulfate, dissolved in 30 grams of deionized water, were added. This was immediately followed by 1998.0 grams of the core prepared in Example 1. A monomer emulsion (MS I) was prepared by mixing 50 grams of deionized water, 3.0 grams of SDS (23%), 10.8 grams of butyl methacrylate, 106.8 grams of methyl methacrylate and 2.4 grams of methacrylic acid and added to the kettle at a rate of 4.5 grams / minute, at a temperature of 80 ° C. Upon completion of MS I, a second emulsion of monomers (ME II) was prepared by mixing 190 grams of deionized water, 3.8 grams of SDS (23%) and 720 grams of styrene. MS II was added to the kettle at a rate of 25.0 grams / minute and a mixture of 1.9 grams of sodium persulfate, dissolved in 75 grams of deionized water was co-fed to the reactor at a rate of 2.5 grams / minute. The temperature of the batch was allowed to increase to 92 ° C. When 457 grams of EM II were added to the pan, 42 grams of ammonium hydroxide were added to the pan and the EM II was continued. Upon completion of EM II and co-loads, the batch was maintained for 5 minutes at 92 ° C. After 5 minutes of retention, the batch was cooled to 85 ° C and a mixture of 0.95 grams of sodium persulfate, dissolved in 20 grams of deionized water, was added to the copper. The contents of the pellet were maintained for 30 minutes at 85 ° C and then cooled to room temperature and filtered to remove any formed clot. The final latex had a solids content of 24.0%, a pH of 10.0 and a particle size of 573 nm, which was an increase in particle size over Example 17 (404 nm); some aggregate of particles was observed, which can count for the increased particle size measured. This increased particle size is an indication of the particle aggregate caused by an increase in the amount of the acid in the nucleus in the aqueous phase and indeed an acid titration showed a higher titratable core acid (14.4%) compared to Example # 17 The dry density of this polymer was determined to be 0.6367 g / cc.

Example 36: (Comparative) A 5-liter, four-necked round bottom flask was equipped with a paddle stirrer, thermometer, nitrogen inlet and reflux condenser. Deionized water, 1700 grams, was added to the kettle and heated to 86 ° C under a nitrogen atmosphere. To the water of a heated pellet, 3.8 grams of sodium persulfate, dissolved in 30 grams of deionized water, were added. This was immediately followed by 189.9 grams of the core prepared in Example 5. An emulsion of monomers (EM I) was prepared by mixing 50 grams of deionized water, 3.0 grams of SDS (23%), 10.8 grams of butyl methacrylate, 106.8 grams of methyl methacrylate and 2.4 grams of methacrylic acid and added to the copper at a rate of 4.5 grams / minute, at a temperature of 80 ° C. Upon completion of the EM I, a second monomer emulsion (ME II) was prepared by mixing 190 grams of deionized water, 3.8 grams of SDS and 720 grams of styrene. MS II was added to the kettle at a rate of 12.5 grams / minute and a mixture of 1.9 grams of sodium persulfate, dissolved in 75 grams of deionized water was co-fed to the reactor at a rate of 2.5 grams / minute. After 10 minutes, the loading regimen of the EM II was increased to 25 grams / minutes. The temperature of the copper was allowed to increase to 92 ° C. When 777 grams of EM II have been added to the copper, 42 grams of ammonium hydroxide were added to the copper. Upon completion of EM II and co-loads, the batch was maintained for 5 minutes at 92 ° C. After 5 minutes of retention, the batch was cooled to 85 ° C and a mixture of 0.95 grams of sodium persulfate, dissolved in 20 grams of deionized water, was added to the copper. The contents of the pellet were maintained for 30 minutes at 85 ° C and then cooled to room temperature and filtered to remove any formed clot. The final latex had a solids content of 27.8%, a pH of 10.2 and a particle size of 570 nm. An acid titration showed good core encapsulation, with only 5.0% of titratable core acid. The dry density of this polymer was determined to be 0.6364 g.

Example 37: (Comparative) A 5-liter, four-necked round bottom flask was equipped with a paddle stirrer, thermometer, nitrogen inlet and reflux condenser. Deionized water, 1700 grams, was added to the kettle and heated to 86 ° C under a nitrogen atmosphere. To the water of a heated pellet, 3.8 grams of sodium persulfate, dissolved in 30 grams of deionized water, were added. This was followed immediately by 189.9 grams of the core prepared in Example 5. An emulsion of monomers (EM I) was prepared by mixing 50 grams of deionized water, 3.0 grams of SDS, 10.8 grams of butyl methacrylate, 106.8 grams of methyl methacrylate. and 2.4 grams of methacrylic acid and added to the kettle at a rate of 4.5 grams / minute, at a temperature of 80 ° C. Upon completion of the EM I, a second monomer emulsion (ME II) was prepared by mixing 190 grams of deionized water, 3.8 grams of SDS and 720 grams of styrene. MS II was added to the kettle at a rate of 25.0 grams / minute and a mixture of 1.9 grams of sodium persulfate, dissolved in 75 grams of deionized water was co-fed to the reactor at a rate of 2.5 grams / minute. After 10 minutes, the loading regimen of EM II was increased to 25 grams / minute. The temperature of the batch was allowed to increase to 92 ° C. When 457 grams of EM II were added to the pan, 42 grams of ammonium hydroxide was added to the pan. Upon completion of EM II and co-loads, the batch was maintained for 5 minutes at 92 ° C. After 5 minutes of retention, the batch was cooled to 85 ° C and a mixture of 0.95 grams of sodium persulfate, dissolved in 20 grams of deionized water, was added to the copper. The contents of the pellet were maintained for 30 minutes at 85 ° C and then cooled to room temperature and filtered to remove any formed clot. The final latex had a solids content of 26.5%, a pH of 10.2 and a particle size of 725 nm, which was an increase in particle size over Example 21 (577 nm). This increased particle size is an indication of particle aggregation caused by an increase in the amount of the core acid in the aqueous phase and indeed an acid titration showed a higher titratable core acid (18.5%) compared to Example # twenty-one. The dry density of this polymer was determined to be 0.6284 g / cc.

Example 38: (Comparative) A 5-liter, four-necked round bottom flask was equipped with a paddle stirrer, thermometer, nitrogen inlet and reflux condenser. Deionized water, 1700 grams, was added to the kettle and heated to 86 ° C under a nitrogen atmosphere. To the water of a heated pellet, 3.8 grams of sodium persulfate, dissolved in 30 grams of deionized water, were added. This was followed immediately by 189.9 grams of the core prepared in Example 5. An emulsion of monomers (EM I) was prepared by mixing 50 grams of deionized water, 3.0 grams of SDS, 10.8 grams of butyl methacrylate, 106.8 grams of methyl methacrylate. and 2.4 grams of methacrylic acid and added to the kettle at a rate of 4.5 grams / minute, at a temperature of 80 ° C. Upon completion of the EM I, a second monomer emulsion (ME II) was prepared by mixing 190 grams of deionized water, 3.8 grams of SDS and 720 grams of styrene. The EM II was added to the kettle at a rate of 12.5 grams / minute and a mixture of 1.9 grams of sodium persulfate, dissolved in 75 grams of deionized water was co-fed to the reactor at a rate of 2.5 grams / minute. After 10 minutes, the loading regimen of EM II was increased to 25 grams / minute. The temperature of the batch was allowed to increase to 92 ° C. When the EM II and co-charges were completed, 42 grams of ammonium hydroxide was added to the copper. The batch was kept for 5 minutes at 92 ° C. After 5 minutes of retention, the batch was cooled to 85 ° C and a mixture of 0.95 grams of sodium persulfate, dissolved in 20 grams of deionized water, was added to the copper. The contents of the pellet were maintained for 30 minutes at 85 ° C and then cooled to room temperature and filtered to remove any formed clot. The final latex had a solids content of 27.3%, a pH of 10.3 and a particle size of 530 nm. An acid titration showed good core encapsulation, with only 2.0% titratable core acid. The dry density of this polymer was determined to be 0.8220 g / cc.

EXAMPLE 39 A 5-Liter, four-necked round bottom flask was equipped with a paddle stirrer, thermometer, nitrogen inlet and reflux condenser. Deionized water, 1700 grams, was added to the kettle and heated to 86 ° C under a nitrogen atmosphere. To the water of a heated pellet, 3.8 grams of sodium persulfate, dissolved in 30 grams of deionized water, were added. This was followed immediately by 189.9 grams of the core prepared in Example 5. An emulsion of monomers (EM I) was prepared by mixing 50 grams of deionized water, 3.0 grams of SDS, 10.8 grams of butyl methacrylate, 106.8 grams of methyl methacrylate. and 2.4 grams of methacrylic acid and added to the kettle at a rate of 4.5 grams / minute, at a temperature of 80 ° C. Upon completion of the EM I, a second monomer emulsion (ME II) was prepared by mixing 190 grams of deionized water, 3.8 grams of SDS and 720 grams of styrene. From MS II, 137 grams were removed and placed separately. The initial portion of EM II was added to the kettle at a rate of 12.5 grams / minute and a mixture of 1.9 grams of sodium persulfate, dissolved in 75 grams of de-ionized water, was co-fed to the reactor at a rate of 2.5 grams / minute. After 10 minutes, the loading regimen of EM II was increased to 25 grams / minute. The temperature of the copper was allowed to increase to 92 ° C. Upon completion of the EM II and co-charges, a mixture of 1 gram of the N, N-diethylhydroxylamine and 16 grams of deionized water were added to the reaction mixture and the batch was cooled to 85 ° C. When the temperature of the copper reached 85 ° C, the portion retained before ME II (137 grams) was added to the reactor, followed by the addition of 42 grams of ammonium hydroxide. The reaction mixture was maintained for 5 minutes at 85 ° C. After 5 minutes of retention, a mixture of 0.95 grams of sodium persulfate, dissolved in 20 grams of deionized water, was added to the copper. The reaction mixture was maintained for 30 minutes at 85 ° C and then cooled to room temperature and filtered to remove any formed coagulum. The final latex had a solids content of 26.0, a pH of 10.2 and a particle size of 580 nm. An acid titration showed good encapsulation of the core with only 5.0% of the titratable core acid. The dry density of this polymer was determined to be 0.5574 g / cc.

Example 40 A 5-liter, four-necked round bottom flask was equipped with a paddle stirrer, thermometer, nitrogen inlet and reflux condenser. Deionized water, 1700 grams, was added to the kettle and heated to 86 ° C under a nitrogen atmosphere. To the water of a heated pellet, 3.8 grams of sodium persulfate, dissolved in 30 grams of deionized water, were added. This was followed immediately by 189.9 grams of the core prepared in Example 5. An emulsion of monomers (EM I) was prepared by mixing 50 grams of deionized water, 3.0 grams of SDS, 10.8 grams of butyl methacrylate, 106.8 grams of methyl methacrylate. and 2.4 grams of methacrylic acid and added to the kettle at a rate of 4.5 grams / minute, at a temperature of 80 ° C. Upon completion of the EM I, a second monomer emulsion (ME II) was prepared by mixing 190 grams of deionized water, 3.8 grams of SDS and 720 grams of styrene. From MS II, 137 grams were removed and placed separately. The initial portion of EM II was added to the kettle at a rate of 12.5 grams / minute and a mixture of 1.9 grams of sodium persulfate, dissolved in 75 grams of deionized water, was co-fed to the reactor at a rate of 2.5 grams / minute. After 10 minutes, the loading regimen of EM II was increased to 25 grams / minute. The temperature of the copper was allowed to increase to 92 ° C. Upon completion of the EM II and co-charges, 42 grams of a 1% solution of the 4-nitrosophenol-magnesium salt in water were added to the contents of the kettle and the bath was cooled to 85 ° C. When the temperature of the copper reached 85 ° C, the portion retained before ME II (137 grams) was added to the reactor, followed by the addition of 42 grams of ammonium hydroxide. The reaction mixture was maintained for 5 minutes at 85 ° C. After 5 minutes of retention, a mixture of 0.95 grams of sodium persulfate, dissolved in 20 grams of deionized water, was added to the copper. The reaction mixture was maintained for 30 minutes at 85 ° C and then cooled to room temperature and filtered to remove any formed coagulum. The final latex had a solids content of 26.8%, a pH of 10.2 and a particle size of 585 nm. An acid titration showed good encapsulation of the core with only 5.4% of the titratable core acid. The dry density of this polymer was determined to be 0.5481 g / cc.

Example 41: (Comparative) A 5-liter, four-necked round bottom flask was equipped with a paddle stirrer, thermometer, nitrogen inlet and reflux condenser. Deionized water, 2000 grams, was added to the kettle and heated to 86 ° C under a nitrogen atmosphere. To the water of a heated pellet, 3.8 grams of sodium persulfate, dissolved in 30 grams of deionized water, were added. This was immediately followed by 188.0 grams of the core prepared in Example 8. A monomer emulsion (EM I) was prepared by mixing 50 grams of deionized water, 3.0 grams of SDS, 12.0 grams of butyl methacrylate, 105.6 grams of methyl methacrylate. and 2.4 grams of methacrylic acid and added to the copper at a rate of 3.0 grams / minute, at a temperature of 80 ° C. Upon completion of EM I, a second monomer emulsion (ME II) was prepared by mixing 160 grams of deionized water, 3.2 grams of SDS and 600 grams of styrene and 1.5 grams of allyl methacrylate. The EM II was added to the kettle at a rate of 12.5 grams / minute and a mixture of 1.9 grams of sodium persulfate, dissolved in 75 grams of deionized water, was co-fed to the reactor at a rate of 2.5 grams / minute. After 10 minutes, the loading regimen of EM II was increased to 25 grams / minute. The temperature of the copper was allowed to increase to 92 ° C. When 650 grams of EM II were fed to the copper, 38 grams of ammonium hydroxide were added to this copper. Upon completion of the EM II and co-loads, the batch was maintained for 5 minutes at 92 ° C. After 5 minutes of retention, the batch was cooled to 85 ° C and a mixture of 0.95 grams of sodium persulfate dissolved in 20 grams of deionized water was added to the pan. The copper was kept for 30 minutes at 85 ° C and then cooled to room temperature and filtered to remove any formed coagulum. The final latex had a solids content of 22.9%, a pH of 10.3 and a particle size of 976 nm. An acid titration showed good encapsulation of the core with only 4.4% of the titratable core acid. The dry density of this polymer was determined to be 0.5247 g / cc.

Example 42: (Comparative) A 5-liter, four-necked round bottom flask was equipped with a paddle stirrer, thermometer, nitrogen inlet and reflux condenser. Deionized water, 2000 grams, was added to the kettle and heated to 86 ° C under a nitrogen atmosphere. To the water of a heated pellet, 3.8 grams of sodium persulfate, dissolved in 30 grams of deionized water, were added. This was immediately followed by 188.0 grams of the core prepared in Example 8. A monomer emulsion (EM I) was prepared by mixing 50 grams of deionized water, 3.0 grams of SDS, 12.0 grams of butyl methacrylate, 105.6 grams of methyl methacrylate. and 2.4 grams of methacrylic acid and added to the copper at a rate of 3.0 grams / minute, at a temperature of 80 ° C. Upon completion of EM I, a second monomer emulsion (ME II) was prepared by mixing 160 grams of deionized water, 3.2 grams of SDS and 600 grams of styrene and 1.5 grams of allyl methacrylate. The EM II was added to the kettle at a rate of 12.5 grams / minute and a mixture of 1.9 grams of sodium persulfate, dissolved in 75 grams of deionized water, was co-fed to the reactor at a rate of 2.5 grams / minute. After 10 minutes, the loading regimen of EM II was increased to 25 grams / minute. When the EM II and co-charges were completed, 38 grams of ammonium hydroxide were added to the copper and the batch was kept for 5 minutes. The temperature of the copper was allowed to increase to 92 ° C. When 650 grams of EM II were fed to the copper, 38 grams of ammonium hydroxide were added to this copper. Upon completion of the EM II and co-loads, the batch was maintained for 5 minutes at 92 ° C. After 5 minutes of retention, the batch was cooled to 85 ° C and a mixture of 0.95 grams of sodium persulfate dissolved in 20 grams of deionized water was added to the pan. The copper was kept for 30 minutes at 85 ° C and then cooled to room temperature and the 0.95 gram mixture of sodium persulfate, dissolved in 20 grams of water, was added to the kettle. This copper was maintained for 30 minutes at 85 ° C and then at room temperature and filtered to remove any formed coagulum. The final latex had a solids content of 22.9%, a pH of 10.2 and a particle size of 1023 nm. An acid titration showed good encapsulation of the core with only 2.7% of the titratable core acid. The dry density of this polymer was determined to be 0.6945 g / cc.

Example 43: (Comparative) A 5-liter, four-necked round bottom flask was equipped with a paddle stirrer, thermometer, nitrogen inlet and reflux condenser. Deionized water, 2000 grams, was added to the kettle and heated to 86 ° C under a nitrogen atmosphere. To the water of a heated pellet, 3.8 grams of sodium persulfate, dissolved in 30 grams of deionized water, were added. This was immediately followed by 195.4 grams of the core prepared in Example 15. An emulsion of monomers (EM I) was prepared by mixing 50 grams of deionized water, 3.0 grams of SDS, 10.8 grams of butyl methacrylate, 106.8 grams of methyl methacrylate. and 2.4 grams of methacrylic acid and added to the copper at a rate of 3.0 grams / minute, at a temperature of 80 ° C. Upon completion of the EM I, a second monomer emulsion (ME II) was prepared by mixing 190 grams of deionized water, 3.8 grams of SDS and 720 grams of styrene. The EM II was added to the kettle at a rate of 12.5 grams / minute and a mixture of 1.9 grams of sodium persulfate, dissolved in 75 grams of deionized water was co-fed to the reactor at a rate of 2.5 grams / minute. After 10 minutes, the loading regimen of EM II was increased to 25 grams / minute. The temperature of the reaction mixture was allowed to increase to 92 ° C. When 650 grams of EM II were fed to the kettle, 42 grams of ammonium hydroxide were added to this pan and the batch was kept at 92 ° C for 5 minutes. After a 5 minute hold, a mixture of 0.95 grams of sodium persulfate, dissolved in 20 grams of deionized water, was added to the pan. The reaction mixture was maintained for 30 minutes at 85 ° C and then cooled to room temperature and filtered to remove any formed coagulum. The final latex had a solids content of 25.5%, a pH of 10.2 and a particle size of 232 nm. An acid titration showed good encapsulation of the core with only 6.4% of the titratable core acid. The dry density of this polymer was determined to be 0.9115 g / cc.

Example 44: (Comparative) A 5-liter, four-necked round bottom flask was equipped with a paddle stirrer, thermometer, nitrogen inlet and reflux condenser. Deionized water, 2000 grams, was added to the kettle and heated to 86 ° C under a nitrogen atmosphere. To the water of a heated pellet, 3.8 grams of sodium persulfate, dissolved in 30 grams of deionized water, were added. This was immediately followed by 195.4 grams of the core prepared in Example 15. An emulsion of monomers (MS I) was prepared by mixing 50 grams of deionized water, 3.0 grams of SDS, 10.8 grams of butyl methacrylate, 106.8 grams of methyl methacrylate. and 2.4 grams of methacrylic acid and added to the copper at a rate of 3.0 grams / minute, at a temperature of 80 ° C. Upon completion of the EM I, a second monomer emulsion (ME II) was prepared by mixing 190 grams of deionized water, 3.8 grams of SDS and 720 grams of styrene. The EM II was added to the kettle at a rate of 12.5 grams / minute and a mixture of 1.9 grams of sodium persulfate, dissolved in 75 grams of deionized water was co-fed to the reactor at a rate of 2.5 grams / minute. After 10 minutes, the loading regimen of EM II was increased to 25 grams / minute. The temperature of the copper was allowed to increase to 92 ° C. When 777 grams of EM II were fed to the copper, 42 grams of ammonium hydroxide were added to this copper. Upon completion of the EM II and co-loads, the batch was maintained for 5 minutes at 92 ° C. After 5 minutes of retention, the batch was cooled to 85 ° C and a mixture of 0.95 grams of sodium persulfate dissolved in 20 grams of deionized water was added to the pan. The copper was kept for 30 minutes at 85 ° C and then cooled to room temperature and filtered to remove any formed coagulum. The final latex had a solids content of 25.2%, a pH of 10.2 and a particle size of 268 nm. An acid titration showed sufficient core encapsulation with only 7.2% of the titratable core acid. The dry density of this polymer was determined to be 0.7688 g / cc.

Example 45: A 5-liter, four-necked round bottom flask was equipped with a paddle stirrer, thermometer, nitrogen inlet and reflux condenser. Deionized water, 22000 grams, was added to the kettle and heated to 86 ° C under a nitrogen atmosphere. To the water of a heated pellet, 3.8 grams of sodium persulfate, dissolved in 30 grams of deionized water, were added. This was followed immediately by 191.1 grams of the core prepared in Example 13. A monomer emulsion (MS I) was prepared by mixing 100 grams of deionized water, 6.0 grams of SDS, 21.6 grams of butyl methacrylate, 213.6 grams of methyl methacrylate. and 4.8 grams of methacrylic acid and added to the copper at a rate of 6.0 grams / minute, at a temperature of 80 ° C. Upon completion of MS I, a second emulsion of monomers (ME II) was prepared by mixing 190 grams of deionized water, 3.8 grams of SDS, 720 grams of styrene and 1.8 grams of allyl methacrylate. From MS II, 137 grams were removed and placed separately. The initial portion of the ME II was added to the kettle at a rate of 12.5 grams / minute and a mixture of 1.9 grams of sodium persulfate, dissolved in 75 grams of deionized water was co-fed to the reactor at a rate of 2.0 grams / minute. After 10 minutes, the EM II regimen was increased to 25 grams / minute. The temperature of the reaction mixture was allowed to increase to 92 ° C. Upon completion of the EM II and co-charges, a mixture of 8 grams of 4-hydroxy TEMPO and 8 grams of deionized water was added to the reaction mixture, and the batch was cooled to 85 ° C. When the reaction mixture reached 85 ° C, the portion left behind ME II (91.4 grams) was added to the reactor, followed by the addition of 42 grams of ammonium hydroxide. The reaction mixture was maintained for 5 minutes at 85 ° C. After holding for 5 5 minutes, a mixture of 0.95 grams of sodium persulfate, dissolved in 20 grams of deionized water, was added and then added to the copper. The reaction mixture was maintained for 30 minutes at 85 ° C and then cooled to room temperature and filtered to remove any formed coagulum. The final latex had a solids content of 25.8%, a pH of 10.1 and a particle size of 237 nm. An acid titration showed good core encapsulation with only 2.9% of the titratable core acid. The dry density of this polymer was determined to be 0.6868 g / cc.

Example 46: (Comparative) A 5-liter, four-necked round bottom flask was equipped with a paddle stirrer, thermometer, nitrogen inlet and reflux condenser. Deionized water, 2200 grams, was added to the kettle and heated to 86 ° C under a nitrogen atmosphere. To the water of a heated pellet, 3.8 grams of sodium persulfate, dissolved in 30 grams of deionized water, were added. This was followed immediately by 189.9 grams of the core prepared in Example 11. A monomer emulsion (MS I) was prepared by mixing 00 grams of deionized water, 6.0 grams of SDS, 21.6 grams of butyl methacrylate, 213.6 grams of methyl methacrylate. and 4.8 grams of methacrylic acid and added to the copper at a rate of 6.0 grams / minute, at a temperature of 80 ° C. By completing MS I, a second emulsion of monomers (ME II) was prepared by mixing 190 grams of deionized water, 3.8 grams of SDS (23%) and 720 grams of styrene. The EM II was added to the kettle at a rate of 12.5 grams / minute and a mixture of 1.9 grams of sodium persulfate, dissolved in 75 grams of deionized water was co-fed to the reactor at a rate of 2.0 grams / minute. After 10 minutes, the loading regimen of EM II was increased to 25 grams / minute. The temperature of the copper was allowed to increase to 92 ° C. When 822 grams of EM II were fed to the copper, 42 grams of ammonium hydroxide were added to this copper. Upon completion of the EM II and co-loads, the batch was maintained for 5 minutes at 92 ° C. After 5 minutes of retention, a mixture of 0.95 grams of sodium persulfate dissolved in 20 grams of deionized water was added to the kettle. The reaction mixture was maintained for 30 minutes at 85 ° C and then cooled to room temperature and filtered to remove any formed coagulum. The final latex had a solids content of 26.1%, a pH of 10.2 and a particle size of 270 nm. An acid titration showed sufficient core encapsulation with only 3.0% titratable core acid. The dry density of this polymer was determined to be 0.7746 g / cc.

Example 47: A 5-liter, four-necked round bottom flask was equipped with a paddle stirrer, thermometer, nitrogen inlet and reflux condenser. Deionized water, 1700 grams, was added to the kettle and heated to 86 ° C under a nitrogen atmosphere. To the water of a heated pellet, 3.8 grams of sodium persulfate, dissolved in 30 grams of deionized water, were added. This was immediately followed by 191.5 grams of the core prepared in Example 15. An emulsion of monomers (EM I) was prepared by mixing 50 grams of deionized water, 3.Q grams of SDS (23%), 10.8 grams of butyl methacrylate, 106.8 grams of methyl methacrylate and 2.4 grams of methacrylic acid were added to the copper at a rate of 3.0 grams / minute at a temperature of 80 ° C. Upon completion of MS I, a second emulsion of monomers (ME II) was prepared by mixing 190 grams of deionized water, 3.8 grams of SDS (23%) and 720 grams of styrene. From MS II, 137 grams were removed and placed separately. The initial portion of the EM II was added to the kettle at a rate of 12.5 grams / minute and a mixture of 1.9 grams of sodium persulfate, dissolved in 75 grams of deionized water was co-fed to the reactor at a rate of 2.5 grams / minute. After 10 minutes, the loading regimen of EM II was increased to 25 grams / minute. The temperature of the copper was allowed to increase to 92 ° C. Upon completion of the EM II and the co-charges, a mixture of 8 grams of the 4-hydroxy TEMPO and 8 grams of deionized water was added to the kettle and the batch cooled to 85 ° C. When the temperature of the copper reached 85 ° C, the portion retained behind the ME II (137.0 grams) was added to the copper, followed by the addition of 42 grams of ammonium hydroxide. The temperature of the copper was maintained at 85 ° C for 5 minutes. After holding for 5 minutes, a mixture of 0.95 grams of sodium persulfate, dissolved in 20 grams of deionized water, was added to the copper. The contents of the pellet were maintained for 30 minutes at 85 ° C and then cooled to room temperature and filtered to remove any formed clot. The final latex had a solids content of 27.5%, a pH of 10.2 and a particle size of 385 nm. An acid titration showed a good encapsulation of the core with only 4.0% of the titratable core acid. The dry density of this polymer was determined to be 0.6226 g / cc.

Example 48: A 5-liter, four-necked round bottom flask was equipped with a paddle stirrer, thermometer, nitrogen inlet and reflux condenser. Deionized water, 1700 grams, was added to the kettle and heated to 86 ° C under a nitrogen atmosphere. To the water of a heated pellet, 3.8 grams of sodium persulfate, dissolved in 30 grams of deionized water, were added. This was immediately followed by 271.5 grams of the core prepared in Example 4. An emulsion of monomers (EM I) was prepared by mixing 50 grams of deionized water, 3.0 grams of SDS (23%), 10.8 grams of butyl methacrylate, 106.8 grams of methyl methacrylate and 2.4 grams of methacrylic acid and added to the kettle at a rate of 4.5 grams / minute, at a temperature of 80 ° C. Upon completion of MS I, a second emulsion of monomers (ME II) was prepared by mixing 190 grams of deionized water, 3.8 grams of SDS (23%) and 720 grams of styrene. From ME II, 91.4 grams were removed and placed separately. The initial portion of EM II was added to the kettle at a rate of 25 grams / minute and a mixture of 1.9 grams of sodium persulfate, dissolved in 75 grams of deionized water was co-fed to the reactor at a rate of 2.5 grams / minute. The temperature of the copper was allowed to increase to 92 ° C. Upon completion of the ME II and the co-charges, a mixture of 8 grams of the 4-hydroxy TEMPO and 8 grams of deionized water were added to the kettle and the batch cooled to 85 ° C. When the temperature of the copper reached 85 ° C, the portion retained behind the ME II (91.4 grams) was added to the copper, followed by the addition of 42 grams of ammonium hydroxide. The contents of the reactor were maintained at 85 ° C for 5 minutes. After holding for 5 minutes, a mixture of 0.95 grams of sodium persulfate, dissolved in 20 grams of deionized water, was added to the copper. The reaction mixture was maintained for 30 minutes at 85 ° C and then cooled to room temperature and filtered to remove any formed coagulum. The final latex had a solids content of 27.6%, a pH of 10.0 and a particle size of 525 nm. An acid titration showed good core encapsulation with only 4.4% of the titratable core acid. The dry density of this polymer was determined to be 0.5979 g / cc.

Example 49: A 5-liter, four-necked round bottom flask was equipped with a paddle stirrer, thermometer, nitrogen inlet and reflux condenser. Deionized water, 2000 grams, was added to the kettle and heated to 86 ° C under a nitrogen atmosphere. To the water of a heated pellet, 3.8 grams of sodium persulfate, dissolved in 30 grams of deionized water, were added. This was immediately followed by 188.5 grams of the core prepared in Example 8. A monomer emulsion (EM I) was prepared by mixing 50 grams of deionized water, 3.0 grams of SDS, 12.0 grams of butyl methacrylate, 105.6 grams of methyl methacrylate. and 2.4 grams of methacrylic acid and added to the copper at a rate of 3.0 grams / minute, at a temperature of 80 ° C. Upon completion of MS I, a second emulsion of monomers (ME II) was prepared by mixing 136 grams of deionized water, 2.7 grams of SDS and 406 grams of styrene, 102 grams of acrylonitrile and 1.5 grams of allyl methacrylate. A third emulsion of monomers (EM III) was prepared by mixing 24 grams of deionized water, 0.5 grams of SDS, 0.2 grams of allyl methacrylate and 90 grams of styrene. The initial portion of the EM II was added to the copper at a rate of 12.5 grams / minute and a mixture of 1.9 grams of sodium persulfate, dissolved in 75 grams of de-ionized water was co-fed to the reactor at a rate of 2.5 grams / minute. After 10 minutes, the EM II regimen was increased to 25 grams / minute. The temperature of the copper was allowed to increase to 92 ° C. Upon completion of the ME II and the co-charges, a mixture of 8 grams of the 4-hydroxy TEMPO and 8 grams of deionized water were added to the kettle and the batch cooled to 85 ° C. When the temperature of the copper reached 85 ° C, MS III was added to the reactor, followed by the addition of 38 grams of ammonium hydroxide. The reaction mixture was maintained for 5 minutes at 85 ° C. After holding for 5 minutes, a mixture of 0.95 grams of sodium persulfate, dissolved in 20 grams of deionized water, was added to the copper. This copper was kept for 30 minutes at 85 ° C and then cooled to room temperature and the contents were filtered to remove any formed coagulum. The final latex had a solids content of 22.5%, a pH of 10.1 and a particle size of 906 nm. An acid titration showed good core encapsulation with only 2.0% of the titratable core acid. The dry density of this polymer was determined to be 0.4539 g / cc.

Claims

CLAIMS 1. A process for preparing emulsion polymer particles, this method comprises: a) supplying an aqueous emulsion of i) a multistage emulsion polymer, comprising a polymer of the core stage and a polymer of the stage of cover, wherein the polymer of the core stage comprises, as polymerized units, from 5 to 100 weight percent, based on the weight of the polymer of the core stage, of a monoethylenically unsaturated hydrophilic monomer, and from 0 to 95 parts by weight, based on the weight of the polymer of the core stage, of at least one non-ionic, monoethylenically unsaturated monomer; and wherein the polymer of the shell stage comprises, as polymerized units, at least 50 weight percent of the non-ionic, monoethylenically unsaturated monomer; ii) a monomer, at a level of at least 0.5 percent by weight, based on the weight of the multi-stage emulsion polymer; and iii) a swelling agent under conditions in which there are no substantial polymerizations of the monomer; and b) reducing the monomer level by at least fifty percent.
2. A process for preparing emulsion polymer particles, this method comprises: a) supplying an aqueous emulsion of i) a multistage emulsion polymer, comprising a polymer of the core stage and a polymer of the shell stage, in The polymer of the core stage comprises, as polymerized units, from 5 to 100 weight percent, based on the weight of the polymer of the core stage, of a monoethylenically unsaturated hydrophilic monomer, and from 0 to 95 parts by weight. weight, based on the weight of the polymer of the core stage, of at least one non-ionic, monoethylenically unsaturated monomer; and wherein the polymer of the shell stage comprises, as polymerized units, at least 50 weight percent of the non-ionic, monoethylenically unsaturated monomer; b) adding an effective amount of one or more polymerization inhibitors or reducing agents, to substantially stop any polymerization; c) supplying a novel at least 0.5 weight percent monomer, based on the weight of the multi-stage emulsion polymer; d) add a swelling agent; and e) reducing the monomer level by at least fifty percent.
3. The method of claim 2, wherein the one or more polymerization inhibitors or reducing agents are added in an amount of 25 to 5,000 ppm, based on the polymer solids.
4. The method of claim 2 or claim 3, wherein one or more polymerization inhibitors are selected from the group consisting of N, N-diethyl-hydroxylamine, N-nitrosodiphenylamine, 2-dinitrophenyl-hydrazine, p-phenylenediamine, phenothiazine, alloocmene, triethyl phosphite, 4-nitrosophenol, 2-nitrophenol, p-aminophenol, 4-hydroxy TEMPO, hydroquinone, p-methoxyhydroquinone, tert-butyl-p-hydroquinone, 2,5-di-tert. -butyl-p-hydroquinone, 1,4-naphthalenediol, 4-tert. -butyl catechol, copper sulfate, copper nitrate, cresol and phenol.
5. The method of claims 1 or 2, wherein the monomer, at a level of 0.5 percent by weight, based on the weight of the multi-stage emulsion polymer, is one or more of the monomers used to prepare the polymer in multi-stage emulsion.
6. The method of claims 1 or 2, wherein the monomer at a level of at least 0.5 percent by weight, based on the weight of the multi-stage emulsion polymer, is a non-ionic monomer.
7. The method of claims 1 or 2, wherein the swelling agent is selected from a volatile base, fixed base, and combinations thereof.
8. The method of claim 1 or 2, wherein the monomer level is reduced to less than 10,000 ppm, based on the polymer solids, by polymerizing the monomer.
9. An aqueous polymer emulsion, comprising water and a swollen, multi-stage emulsion polymer, in which the dry bulk density of the multi-stage swollen emulsion is: less than 0.77 g / cc, when the swollen emulsion polymer, multi-stage, has a particle size below 275 nm; less than 0.74 g / cc, when the swollen, multi-stage emulsion polymer has a particle size of 275 to 500 nm; less than 0.59 g / cc, when the swollen, multi-stage emulsion polymer has a particle size of 501 to 750 nm; less than 0.46 g / cc, when the swollen, multi-stage emulsion polymer has a particle size of 751 to 1300 nm.