KR100468600B1 - Impact-resistant core-shell emulsion polymer containing pores in the particles and method for preparing the same - Google Patents

Abstract

The present invention relates to a method for preparing an impact-resistant core-shell emulsion polymer containing pores in a particle, wherein the acid monomer, ethylene is added to a seed particle prepared by polymerizing an ethylenically unsaturated monomer, an emulsifier and a radical initiator, and optionally an acid equivalent. Adding an unsaturated monomer and a crosslinking agent to prepare alkali swellable particles by an emulsion polymerization method; Preparing an elastomeric rubbery polymer by reacting the swellable particles with 0.1-20% by weight of an acid monomer, 99.85-75% by weight of a relatively low Tg, and 0.05-5% by weight of a crosslinking agent; Neutralizing the elastomeric rubbery polymer to a pH in the range of 7 to 12; And adding to the neutralized elastomeric rubber polymer a mixture of a hard skin polymer made of an acrylic monomer having a relatively high Tg and a rubber phase forming monomer, and a mixture made of a hard skin forming monomer including a crosslinking agent and a chain regulator. A step of preparing an interlayer copolymer by emulsion polymerization, wherein the final emulsion polymer has a particle size of 0.15 to 0.4 micron, a single pore diameter of 0.05 to 0.2 micron, and an acid monomer contained in the alkaline swellable particles. It is 15 to 40% by weight, the glass transition temperature of the elastomeric rubber-like polymer is -20 ℃ or less, the glass transition temperature of the interlayer copolymer is 0 to 40 ℃ relates to a core-shell emulsion polymer and a method for producing the same.

Description

Impact-resistant core-shell emulsion polymer containing pores in particles and method for preparing same

The present invention improves weather resistance and impact resistance in the composition of hard thermoplastics, polyvinylchloride (hereinafter referred to as "PVC"), polystyrene, styrene-acrylonitrile (SAN) copolymers and polymethylmethacrylate (PMMA). The present invention relates to a core-shell emulsion polymer for acrylic impact modifiers and a method of manufacturing the same, and more particularly, to an elastomeric impact modifier emulsion comprising a rubber-like particle and a hard shell polymer grafted to the rubber-like particle. In the manufacture of rubber, it is designed to contain a single spherical or non-spherical pores inside the rubbery particles to replace some expensive titanium dioxide used as a white opaque agent to reduce the cost of the PVC molded product, the rubber phase in the hard shell forming step Continuous composition change emulsion polymerization method of a mixture of polymer forming monomer, crosslinking agent and hard shell forming monomer Including the interlayer copolymer prepared in the present invention, the concentration gradient and crosslinking density of the monomers were continuously changed between the copolymerization layers, thereby reducing the reduction of rubber components due to the pores inside the particles. It is designed to include most of the outer shell and hard shell-forming monomers in the majority of the surface of the rubber particles to modify the hard tendency to form a hard shell forming monomer containing pores inside the particles that can completely encapsulate the rubber particles. It relates to an impact core-shell emulsion polymer and a method for preparing the same.

Rigid PVC resin has good physical properties and is widely used in building interiors, exteriors, and pipes.Because of resin alone, thermal stability is poor, so it is thermally decomposed during extrusion processing, and its impact strength is weak.The melt is blown to the inner wall of the mold during extrusion processing. Because of the disadvantage of poor appearance, additives such as stabilizers, lubricants, plasticizers and impact modifiers are used to compensate for the properties of these compositions. In particular, impact modifiers used to improve the impact resistance and extrusion / injection workability of rigid PVC resins include halogenated polyethylene (CPE), ethylene-vinylacetate (EVA), acrylonitrile-butadiene-styrene (ABS), and methyl methacrylate. There are acrylate-butadiene-styrene (MBS) and acryl-based, and there are differences in its use and advantages / disadvantages depending on the resin type. Among them, the acrylic impact modifier has a completely saturated structure after manufacture, so that the impact strength does not decrease even when exposed to the outdoors for a long time, and the discoloration degree is small, and it provides excellent impact resistance even under a wide range of processing conditions and a small amount during PVC molding. Most used.

Methods of preparing coreshell-emulsion polymers for acrylic impact modifiers used to improve the impact resistance of hard PVC resins are described in US Pat. Nos. 3,678,133, 3,655,825 and 4,096,202 and the like. U. S. Patent No. 3,678, 133 discloses a rubbery core emulsion comprising an alkyl acrylate monomer having at least 50 parts by weight of a C ₂ -C ₈ alkyl group, in particular butyl acrylate (Tg = 55 ° C.) and a crosslinking agent. In the second step, the core-grafted with an alkyl methacrylate monomer having at least 50 parts by weight of a C ₁ -C ₄ alkyl group, especially methyl methacrylate (Tg = 105 ° C.), in the presence of the core prepared in step ₁ Mention is made of methods for making shell emulsions.

In general, the impact modifier emulsion is separated into a powder having an average particle diameter of about 150 microns through a flocculation and drying process, and the PVC matrix (MATRIX) is applied by the high temperature applied to the extruder, the shear force and the frictional force applied to the extruder during the PVC extrusion. Are dispersed together with other additives. In other words, the impact modifier dispersed by dispersing the emulsion primary particles (rubber phase has a particle size of about 0.15-0.25 microns) in the PVC matrix, and the molded article is formed because the elastic rubber phase is present in the heterogeneous phase by the plasticity mechanism. Even after cooling, the impact from the outside is alleviated and the impact resistance of the hard PVC resin is improved by blocking the progress of cracks. However, the rubbery polymer particles of the polymer prepared by the prior art do not give opacity due to the small refractive index difference from the PVC matrix.

Generally, titanium dioxide, which is a white pigment used in aqueous coatings, paper coatings and molding compositions, is used as an additive to give the white opacity of PVC resin. In fact, for PVC windows and window frames, about 5-10 parts by weight of titanium dioxide is used based on 100 parts by weight of PVC resin. However, titanium dioxide is expensive and acts as a factor to increase the cost of PVC molded articles when used alone, and causes environmental pollution by titanium during aging.

On the other hand, Korean Patent No. 79058 refers to a method for producing a plastic pigment having a hollow inside the particles used as an opaque agent in a white or light aqueous coating, paper coating and molding composition. Its contents form a core from a vinyl monomer having a carboxylic acid group and a general vinyl monomer mixture and polymerize the coating-forming vinyl monomer mixture in the presence of the core particles. And, by swelling the core inside the particle by a process of neutralizing the carboxylic acid group of the core with a base to form pores by volatilizing the water inside the particle during drying, it can withstand the shrinkage generated during the drying process at room temperature The selection criteria of the epidermal forming polymer was set to a glass transition temperature (Tg) and toughness index of 40 ° C or higher.

However, during the PVC molding, the temperature of the melt (melt) transferred by the screw in the extruder rises to almost 200 ° C. Therefore, when the hollow-containing polymer prepared by the above method is applied, it is generated during drying at room temperature. Pore loss is caused by the softening of the polymer instead of the shrinking force, which cannot give any opacity. In addition, it is known that the impact resistance of the PVC molded article depends on the rubber content and the crosslinking density of the rubber phase, if the fine pores are formed in the core-shell emulsion polymer for impact reinforcement prepared by the above-described method, the rubber content is reduced The impact resistance of PVC moldings is reduced.

Accordingly, an object of the present invention is to provide a method for producing a core-shell emulsion polymer for impact reinforcement containing a single spherical or non-spherical pores that can solve the above problems.

Another object of the present invention is to provide a core-shell emulsion polymer for impact reinforcement containing a single spherical or non-spherical pores prepared by the above method.

The method of the present invention for achieving the above object;

In the method for producing an impact resistant core-shell emulsion polymer containing pores in the particles,

(a) adding alkali monomers, ethylenically unsaturated monomers and crosslinking agents to seed particles prepared by polymerizing ethylenically unsaturated monomers, emulsifiers and radical initiators, and optionally acid equivalents, to prepare alkali swellable particles by emulsion polymerization;

(b) reacting the swellable particles with 0.1-20 wt% of an acid monomer, 99.85-75 wt% of a relatively low Tg alkyl (meth) acrylate monomer, and 0.05-5 wt% of a crosslinking agent to prepare an elastomeric rubbery polymer step;

(c) neutralizing the elastomeric rubbery polymer to a pH in the range of 7 to 12;

(d) In the neutralized elastomeric rubber polymer, a first supply tank is charged with a relatively low Tg, an alkyl (meth) acrylate and a crosslinking agent, which is a rubber-forming monomer, and a second supply connected in parallel with the first supply tank. Preparing an interlayer copolymer by adding a chain regulator and an alkyl methacrylate having a relatively high Tg, which is a hard shell forming monomer, to emulsion polymerization by a continuous composition change addition method; And

(e) forming a hard skin polymer composed of an acrylic monomer having a relatively high Tg in the interlayer copolymer,

The particle size of the final emulsion polymer is 0.15 to 0.4 microns, the diameter of a single pore after drying is 0.05 to 0.2 microns, the acid monomer contained in the alkali swellable particles is 15 to 40% by weight, the glass transition temperature of the elastomeric rubber polymer Is less than -20 ° C, the glass transition temperature of the interlayer copolymer is from 0 to 40 ° C, 40-75% by weight of alkyl methacrylate having a relatively low Tg relative to the interpolymer forming monomer mixture, and Tg is relatively It consists of a process for producing a core-shell emulsion polymer, characterized in that the high alkyl methacrylate is 20 to 60% by weight and the crosslinking agent is 0 to 5% by weight.

Looking at the present invention in more detail as follows.

The present invention synthesizes alkali swellable particles by a conventional emulsion polymerization method, and then an elastomeric rubber polymer composed of an acrylic monomer having a relatively low Tg, a crosslinking agent and an acid equivalent and an acrylic having a relatively high Tg grafted to the rubber particles. In preparing an impact modifier emulsion polymer made of a hard shell polymer made of monomers, first, a neutralization process of swelling the resulting polymer particles with a base at an elevated temperature to volatilize water from the inside of the particles during drying to form pores. To reduce the cost of PVC molded parts by replacing some expensive titanium dioxide used as a white opaque agent, and secondly, continuously changing the mixture of the rubbery polymer forming monomer, the crosslinking agent and the hard shell forming monomer in the hard shell forming step. Including interlayer copolymer prepared by emulsion polymerization method Designed to continuously change the concentration gradient and crosslinking density of monomers between copolymerization layers to improve the reduction of rubber components due to the pores inside the particles. Third, the inner layer of the interlayer copolymer contains most of the rubbery polymer-forming monomer and crosslinking agent. The outer skin of the interlaminar copolymer is designed to include most of the hard shell forming monomers, thereby modifying the surface of the rubber particles to a hard tendency so that the hard shell forming monomers completely encapsulate the rubber particles, thus having a high rubber content. It is characterized by the improvement of over-agglomeration during drying and caking during storage due to incomplete encapsulation. In addition, the present invention also includes a manufacturing method of forming a non-spherical pores such as peanut-like inside the particles by fine-aggregating the emulsion-polymerized alkali swellable polymer and then proceeding to the above-described manufacturing process.

The continuous composition change addition method used in the present invention is mentioned in Korean Patent No. 79058, and the method of preparing the interlayer copolymer of the present invention using the continuous composition change addition method is described below using a single step polymerization of A and B monomers as an example. same. Here, A is a mixture of a rubbery forming monomer and a crosslinking agent, or a mixture comprising the same, and B is an enveloped monomer or a mixture comprising the same.

In general, in the emulsion polymerization, a mixture of a certain composition is introduced into a reaction system at a predetermined time by a predetermined addition rate from a monomer supply tank, whereas a monomer mixture of the same composition is always introduced into the reaction system. , The first supply of uniformly mixed by agitation while simultaneously supplying the composition of the second supply tank to the first supply tank in order to put B into the second supply tank and connect the two supply tanks in series and simultaneously supply to the reaction tank By supplying the monomer mixture of the tank to the reaction tank, a method of continuously changing the composition of the inflow monomer according to the conversion rate was used. By controlling the addition rate of the two feed tanks, the A-rich copolymer is present inside the particles of the interlayer copolymer, and the B-rich copolymer is present in the particle surface layer. do.

In addition, one of the features of the present invention is that at any point in time by maintaining monomer starved conditions that properly control the absolute feed rate and limit reaction conditions of the monomers to maximize the monomer content present in the reaction system at some point. The polymerization rate (Rp) and the feed rate (Ra) should be adjusted to maintain the instaneous conversion of 70% or more, preferably 85% or more.

At this time, the only monomer composition (C ₂ ) at a given conversion rate or time is represented by the following formula (1).

[Equation 1]

C ₂ = C ₁ ·-(C ₁ ·-C ₂ ·) (1- α ) ^x

Here, C ₁ · and C ₂ · denote initial monomer compositions of the first supply tank and the second supply tank, respectively, α is the conversion ratio, and x is the ratio of the amount of the second supply monomer to the amount of the first supply monomer.

Hereinafter, the present invention will be described in detail for each step.

The method for preparing an impact-resistant core-shell emulsion polymer containing a single spherical or non-spherical inner pore simultaneously functioning as an impact strengthening agent and an opaque agent of a rigid PVC molding according to the present invention is first prepared by the conventional emulsion polymerization method. Manufacture. Then, using the alkali swellable particles to prepare an elastomeric rubber-like polymer made of a relatively low Tg acrylic monomer, a crosslinking agent and an acid monomer, it is swollen with a base at an elevated temperature to form internal pores upon drying. Neutralize Next, after preparing the interlayer copolymer obtained by emulsion-polymerizing the soft rubber forming monomer, the crosslinking agent, and the hard shell forming monomer by a continuous composition change addition method, a hard shell polymer made of an acryl monomer having a relatively high Tg is prepared. On the other hand, finely aggregate the emulsion-polymerized alkali swellable polymer particles, and may include a manufacturing step of forming a non-spherical pores such as peanut-like inside the particles by the above-described manufacturing process.

Alkali swellable particles can be prepared in a single step, but are prepared in multiple steps including the preparation of the seed polymer to facilitate control of the final particle size and its distribution, and seeding with a portion of the core forming monomer to simplify the process. The process to make is preferable. Seed particles are prepared by polymerizing ethylenically unsaturated monomers, optionally acid equivalents, emulsifiers and radical initiators.

The seed particle preparation step is intended to provide a nucleus particle in which the acid monomer mixture is polymerized and grown thereon in a subsequent step, and may include or may not contain a small amount of acid equivalent, and the particle size may be 0.02 to 0.1 micron. Is preferably 0.03 to 0.1 micron. The acid monomers used are selected from acrylic acid, methacrylic acid, itaconic acid, and maleic acid or anhydrides thereof, preferably from 0 to 10% by weight, preferably from 0 to 5% by weight, based on the monomer mixture, and ethylene copolymerized. The unsaturated monomer is selected from at least one of styrene, vinyltoluene, ethylene, butadiene, vinyl acetate, vinyl chloride, vinylidene chloride, alkyl acrylates having 1 to 8 carbon atoms and alkyl methacrylates having 1 to 4 carbon atoms.

Emulsifiers are used in the range of 0.1 to 3.0% by weight, based on monomer weight, alone or in combination with anionic or nonionic emulsifiers. Representative nonionic emulsifiers are octylphenoxy polyethoxyethanol and nonylphenoxy polyethoxyethanol, among which Preference is given to those having a hydrophilic-hydrophobic ratio (HLB) of 5 to 15. Representative anionic emulsifiers include alkyl or alkyl-aryl sulfate metal or ammonium salts, and alkylphenoxy ethylpolyethoxysulfate sodium or ammonium salts, especially those having 3 to 6 ethoxy groups in the preemulsification of the core monomer mixture. Suitable.

The water-soluble radical initiator added to the reaction mixture may be used alone by thermal dissociation initiators such as ammonium persulfate, sodium persulfate and potassium persulfate, or with the initiator and a reducing agent such as alkali metal sulfate, hyposulfate and sodium formaldehyde sulfoxylate. Oxidation-reduction initiators in the form of a mixture may be used, the amount of use of which is based on monomers in the range of 0.1 to 2% by weight and the reaction temperature is set so that the radical production half-life is in the range of 30 to 150 minutes. These emulsifiers, initiators, and the criteria for setting the reaction temperature are common to the emulsification polymerizations and are also applied to subsequent steps.

When the seed is formed through the seed forming step as described above, the secondary synthesis step using the hydrophilic monomer, that is, the synthesis step of the alkali swellable particles is performed. In this step, it contains 15 to 40% by weight of acid monomer, 39 to 85% by weight of general ethylenically unsaturated monomer, and 0 to 2% by weight of crosslinking agent. Representative types of each monomer are as described above. Is aryl (meth) acrylate, di (meth) acrylate, such as ethylene glycol dimethacrylate, 1,3-butanediol dimethacrylate, 1,4-butanediol di (meth) acrylate and 1,6- Hexanediol diacrylate and the like.

The amount of the alkali-swellable polymerizable monomer mixture is suitable in the range of 5 to 30% by weight based on the monomer mixture used in the whole process, regardless of the presence of the seed step, and the particle diameter of the polymer is 0.05 to 0.2 in the non-swelled state below pH = 5. It should be designed to be micron.

Plastic pigments, which are typically used as opaque agents in aqueous paints and paper coating compositions, are designed to have an alkali swellable polymer particle size larger than the scope of the invention, but the polymers produced in the present invention not only impart opacity but also act as impact modifiers. As described above, the above-described particle diameter range is suitable.

Typically, preparing the elastomeric rubbery polymer provides internally crosslinked soft polymer particles containing only alkyl (meth) acrylate and a crosslinking agent having a relatively low Tg, but in the present invention, swelling alkyl swellable particles with a base. And acid monomers to provide a passage for the base to pass through the particles to have internal pores upon drying. This step contains from 0.1 to 20% by weight of acid monomer, 99.85 to 75% by weight of relatively low Tg alkyl (meth) acrylate monomer and from 0.05 to 5% by weight of crosslinking agent. The alkyl (meth) acrylate monomer preferably uses butyl acrylate, 2-ethylbutyl acrylate or 2-ethylhexyl acrylate having a relatively low Tg. The monomer mixture used is suitable for 40 to 70% by weight based on the monomer used in the whole process, Tg is less than -20 ℃, the particle size is suitable for 0.1 to 0.3 microns.

The neutralization process, which is an essential step in the manufacture of hollow particles, is preferably performed after the elastic rubber polymer is prepared in the case of the present invention. As a method, the neutralization process may be carried out in a single process, and in the subsequent process, a method of mixing and supplying to the emulsion mixture of the first supply tank may be supplied. The base used as the neutralizing agent is selected from volatile bases of ammonia and organic amines or from fixed bases of alkali metal hydroxides such as sodium hydroxide and sodium peroxide. The amount of the base used is such that the pH of the emulsion polymer dispersion after neutralization is within the range of 7 to 12. It is good. The emulsion particle size prepared in the above processes is suitable for 0.15 to 0.4 micron and the diameter of the internal pores after drying is suitable for 0.05 to 0.3 micron, preferably 0.05 to 0.2 micron.

The hard shell forming step encapsulates the elastic rubbery particles to facilitate the separation of emulsion particles from the water phase during the drying process and to maximize the compatibility of the PVC matrix with the impact modifier. Encapsulation monomers may be used in the rubber phase formation step alone, using alkyl methacrylate monomers such as methyl methacrylate and ethyl methacrylate, which are relatively high Tg among those exemplified in explaining the rubber phase preparation step. Although may be used in combination with relatively low monomers, it is important to select the outer polymer Tg is 50 ℃ or more, preferably 65 to 120 ℃. The monomer content used is suitably 15 to 30% by weight of the monomer mixture included in the overall process. In addition, chain regulators are used to control the molecular weight of the hard shell polymer, examples of which include mercapto acetic acid, 2-mercapto propionic acid, 3-mercapto propionic acid, n-dodecyl mercaptan, t-dodecyl mercaptan, Carbon tetrachloride, bromo trichloromethane and the like, and an amount of 0.1 to 0.5% by weight based on the shell-forming monomer is suitable.

In the hard skin forming step, the alkyl (meth) acrylate having a relatively low Tg of the elastomeric rubber phase forming monomer, in particular butyl acrylate and a crosslinking agent and the alkyl methacrylate having a relatively high Tg of the shell forming monomer, in particular methyl methacrylate It includes interlayer copolymer composed of a mixture, characterized in that the emulsion mixture by continuously changing the mixture of these mixtures. The interlayer copolymer prepared by the continuous composition change addition method of the present invention includes a rubber-forming monomer and a crosslinking agent in the first supply tank, and an envelope-forming monomer in the second supply tank, so that the first supply tank is connected to the reaction tank. The second feed tank is connected in parallel to the first feed tank, and then the constant feed rate of the two feed tanks is constant or different so that the inner shell is made of a soft copolymer composed mostly of rubbery-forming monomers and crosslinking agents. The copolymer is made of a hard copolymer composed mostly of hard monomers, so that the concentration gradient and crosslinking density of the monomers are continuously changed. The interlayer copolymer thus prepared has a hard tendency to modify the surface of the rubbery particles so that the hard encapsulation monomers completely encapsulate the rubbery particles so that the rubbery particles which are not completely encapsulated are reaggregated during the coagulation / drying process. It can reduce the productivity and improve the caking problems and the impact resistance and gloss degradation of the molding during storage, as well as compensate for the reduction of the rubbery content by the internal pores.

The weight ratio of the monomer mixtures used in the interlayer copolymer of the present invention is 10 to 20% by weight based on the monomer mixture used in the overall process, and the alkyl acrylate having a relatively low Tg uses butyl acrylate, the amount of which is used. 40-75 wt% of the silver interpolymer forming monomer mixture, the relatively high Tg alkyl methacrylate is methyl methacrylate, the amount of the use is 20 to 60 wt%, the crosslinking agent is 0 to 5 wt% Use%. On the other hand, the copolymer Tg is preferably designed from 0 to 40 ℃, the ratio of the first supply tank and the second supply tank is preferably 1: 1 to 3: 1.

In addition, the present invention includes a step of forming a non-spherical pores such as peanut-like to widen the blocking area for light to emulsify the alkali swellable polymer to further maximize the hiding effect, and then fine agglomeration.

In the coagulation method of the present invention, a coagulation process using an inorganic salt is preferable in consideration of the neutralization process. The inorganic salt used is selected from sodium chloride, calcium chloride and ammonium chloride, and the content thereof is 0.01 to 5% by weight based on the alkali swellable polymer. Is suitable. And in order to prevent partial over-aggregation, it is preferable to prepare the inorganic salt in 5% or less aqueous solution.

Emulsified polymer for internal pore-containing impact reinforcement prepared by the present invention is made of a resin of a powder state having an average particle diameter of about 100 to 300 microns through agglomeration and drying process, mixed with a plasticizer, lubricant, stabilizer, filler during PVC molding It is used.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the scope of the present invention is not limited to the following Examples.

Example 1

Preparation of Seed Polymer

400 parts by weight of ion-exchanged water, 0.5 parts by weight of sodium bicarbonate and 0.5 parts by weight of sodium dodecylbenzenesulfonate were added to a 1 L four-necked flask equipped with a thermometer, a dropping tank, a cooler, and a stirrer, and then heated to 80 ° C. An aqueous solution of 0.45 parts by weight of persulfate was dissolved in 30 parts by weight of ion-exchanged water. Emulsion state mixture consisting of 40 parts by weight of ion-exchanged water, 0.05 parts by weight of sodium dodecylbenzenesulfonate, 52 parts by weight of butyl acrylate, 66 parts by weight of methyl methacrylate and 1.4 parts by weight of methacrylic acid while maintaining the reaction temperature at 80 ° C. Was slowly added dropwise over 1 hour, then aged for 1 hour and cooled to prepare a seed polymer. At this time, the particle size was 38 nm and the solid content was 19.7% as measured by the light scattering measuring device.

Preparation of Alkaline Swellable Particles

414.8 parts by weight of ion-exchanged water and 30 parts by weight of the seed polymer were added to a 2 L four-neck flask, and heated to 80 ° C., followed by adding an aqueous solution of 2.0 parts by weight of sodium percellate dissolved in 50 parts by weight of ion-exchanged water. 115 parts by weight of ion-exchanged water, 0.5 parts by weight of sodium dodecylbenzenesulfonate, 55 parts by weight of butyl acrylate, 190 parts by weight of methyl methacrylate, 105 parts by weight of methacrylic acid and aryl methacrylate while maintaining the reaction temperature at 80 ° C. The emulsion mixture consisting of 1.5 parts by weight was slowly added dropwise over 2 hours, then aged for 1 hour and cooled to prepare an alkali swellable dispersion. The particle diameter measured by the light scattering apparatus was 103 nanometers and solid content was 34.8%.

Preparation of Elastomeric Rubber Polymer

Into a 2 L four-necked flask, 25.5.4 parts of ion-exchanged water was charged with 335.5 parts by weight of the alkaline swellable dispersion and 1.28 parts by weight of sodium persulfate, and the temperature was raised to 80 ° C. Emulsified state consisting of 164.1 parts by weight of ion-exchanged water, 1.28 parts by weight of sodium dodecylbenzenesulfonate, 254.4 parts by weight of butyl acrylate, 7.6 parts by weight of methacrylic acid, and 1.28 parts by weight of 1,4-butanediol diacrylate. The mixture is slowly added for 1.5 hours and then aged for 1 hour to prepare an elastomeric rubbery polymer. The particle diameter measured by the light scattering apparatus was 180 nm.

Neutralization stage

At the same temperature, ammonia water was slowly added dropwise to maintain the dispersion pH near 9 for 1 hour. The average particle diameter was 189 nm.

Preparation of Interlayer Copolymer

The first supply tank was connected to the reaction flask containing the polymer passed through the neutralization step, and the second supply tank was installed in the first supply tank, followed by 37.7 parts by weight of ion-exchanged water and 0.64 parts by weight of sodium dodecylbenzenesulfonate. , An emulsion mixture consisting of 31.8 parts by weight of butyl acrylate, 31.8 parts by weight of 2-ethylhexyl acrylate and 0.67 parts by weight of 1,4-butanediol diacrylate was prepared in the first feed tank, and 37.7 parts by weight of ion-exchanged water and sodium An emulsified mixture consisting of 0.38 parts by weight of dodecylbenzenesulfonate, 57.6 parts by weight of methyl methacrylate and 6 parts by weight of butyl acrylate is prepared in a second feed tank.

An aqueous solution in which 0.64 parts of sodium persulfate was dissolved in 9.8 parts of ion-exchanged water was introduced into the reaction flask, and supplied from the second supply tank to the first supply tank having a stirring device at a rate of 1.7 parts by weight / min. The polymerization was carried out while feeding the reaction flask from the first feed tank at a rate of 1.7 parts by weight / min. After the feeding of the monomer mixture is completed, the mixture is aged for 1 hour to prepare an interlayer copolymer.

Preparation of Hard Sheath Copolymer

Continuously 1.5 hours of an emulsified mixture consisting of 88.6 parts by weight of ion-exchanged water, 0.64 parts by weight of sodium persulfate, 0.67 parts by weight of sodium dodecylbenzenesulfonate, 115.1 parts by weight of methyl methacrylate and 12.8 parts by weight of butyl acrylate, After ripening for time, the resultant is cooled to room temperature to prepare a final emulsion polymer.

The average particle diameter of the final emulsion polymer was 225 nm, the pore diameter was 93 nm, the solid content was 42%, the viscosity was 57 centipoise.

Example 2

Emulsified and polymerized in the same manner as in Example 1, but in preparing the interlayer copolymer, 31.8 parts by weight of butyl acrylate and 85.1 parts by weight of butyl acrylate instead of 31.89 parts of 2-ethylhexyl acrylate in the first feed tank. A mixture was prepared, and an emulsified mixture was prepared with 38.2 parts by weight of methyl methacrylate and 4.3 parts by weight of butyl acrylate instead of 57.6 parts by weight of methyl methacrylate and 6 parts by weight of butyl acrylate in a second feed tank, followed by preparing a first feed The emulsified mixture of the tank is fed into the reaction flask at a rate of 2.1 parts by weight / min to feed the emulsified mixture of the second feed tank at a rate of 1.3 parts by weight / min to the first feed tank to prepare an interlayer copolymer. Subsequent reaction processes were carried out in the same manner as in Example 1, and the average particle diameter of the final emulsion polymer was 230 nm, the average pore size was 92 nm, and the solid content was 42%.

Example 3

An alkali swellable dispersion was prepared in the same manner as in Example 1, and then 450 parts by weight instead of 335.5 parts by weight of the alkali swellable dispersion was prepared in the following process. The average particle diameter of the final emulsion polymer observed with an electron microscope was 215 nm, and the average pore diameter was 90 nm.

Example 4

After preparing an alkaline swellable dispersion in the same manner as in Example 1, 250 parts by weight of ion-exchanged water and 335.5 parts by weight of the alkali swellable dispersion were added to a 2 L four-neck flask, and 230 parts by weight of an aqueous solution of 0.5% aqueous ammonium chloride was slowly added at room temperature. The solution was kept in that state for 30 minutes, heated to 80 ° C., and an aqueous solution of 1.28 parts by weight of sodium persulfate was added to 36.4 parts by weight of ion-exchanged water, and proceeded in the same manner as in Example 1 below. It was confirmed that the pores of the particles observed under an electron microscope were non-spherical.

Comparative Example 1

For the purpose of comparison with Example 1 above, a dispersion was prepared which did not contain an alkali swellable polymer, ie an elastomeric rubbery polymer-interlayer copolymer-hard shell polymer.

Into a 5-liter four-necked flask equipped with a thermometer, a dropping tank, a cooler, and a stirrer, 825.5 parts by weight of ion-exchanged water and 2.73 parts by weight of sodium persulfate were heated, and the temperature was raised to 80 ° C. 39.7 in an emulsified mixture consisting of 500 parts by weight of ion-exchanged water, 9.4 parts by weight of Rhodapex CO-436 (manufactured by Long Franca), 775.1 parts by weight of butyl acrylate and 3.89 parts by weight of 1,4-butanediol diacrylate. Add parts by weight and hold for 10 minutes. Since the heat is generated, the temperature is maintained at 86 ° C. and the remainder of the emulsion mixture is slowly added dropwise at a rate of 10.4 parts by weight, and at the same time, 0.43 parts by weight of an aqueous solution in which 1.17 parts by weight of sodium persulfate is dissolved in 50 parts by weight of ion-exchanged water. Drop at speed. After dropping is completed, the mixture is aged for 90 minutes to prepare an elastomeric rubbery core polymer. It was 160 nm when the particle diameter at this time was measured with the light scattering measuring apparatus.

Continuously an emulsified mixture consisting of 115 parts by weight of ion-exchanged water, 3.36 parts by weight of Rhodapex CO-436, 96.9 parts by weight of butyl acrylate, 96.9 parts by weight of 2-ethylhexyl acrylate and 0.97 parts by weight of 1,4-butanediol diacrylate. Prepared in a first feed tank, an emulsified mixture consisting of 115 parts by weight of ion-exchanged water, 1.15 parts by weight of Rhodapex CO-436, 175.3 parts by weight of methyl methacrylate and 18.4 parts by weight of butyl acrylate is prepared in a second supply tank.

An aqueous solution in which 1.95 parts by weight of sodium persulfate was dissolved in 30 parts by weight of ion-exchanged water was injected into the reaction flask, and fed from a second supply tank to a first supply tank having a stirring device at a speed of 5.1 parts by weight / min. The polymerization was carried out while feeding the reaction flask from the first feed tank at a rate of 5.1 parts by weight / min. After supply of the monomer mixture was completed for 1 hour to prepare an interlayer copolymer. This particle size was 186 nm.

An emulsified mixture consisting of 270 parts by weight of ion-exchanged water, 1.95 parts by weight of sodium persulfate, 2.06 parts by weight of Rhodapex CO-436, 350.5 parts by weight of methyl methacrylate and 39 parts by weight of butyl acrylate was added dropwise at a rate of 9.5 parts by weight / min. After aging for 90 minutes, ammonia was added 21 parts by weight while cooling to room temperature to terminate the reaction. The emulsion polymer having the structure of the elastomeric rubber-like core-layer copolymer-shell thus prepared had an average particle diameter of 210 nm, a solid content of 44.7%, a viscosity of 32 centipoise, and a pH of 9.8.

Test Example 1

Example 1, 2, 3 and 4, Comparative Example 1 and OP-62 (Rom and Haas), a plastic pigment applied as an opaque agent in the water-based coating composition is dried in a spray dryer (niro dryer, Denmark) to powder Was prepared.

The compound was prepared by compounding according to the following Table 1 and then extruded under the same conditions to prepare a sheet. In Table 1, the unit is parts by weight.

TABLE 1

* 1) KM 334 melting (Rom and Haas)

The physical properties of impact modifiers containing pores therein prepared by the present invention were compared with conventional impact modifiers. In Table 1, the formulations 1 and 2 were tested.

TABLE 2

1.Caking property (Compaction No .:%): Fill the powder into the box, put the weight of 1400g and leave it at 50 ℃ for 7 days and filter it with 500Mesh.

                         Remaining powder agglomerate weight at 500mesh

∴ Compaction No .:%) = ━━━━━━━━━━━━━━━━ × 100

                          Initially charged powder weight in box

2. Izod notch impact strength (Kgcm / cm): KS M 3055

3. Whiteness: L value specified by the colorimeter

The impact modifier powder prepared in Example 1 was applied based on compounding formulation 3 to find out how much impact modifier containing pores therein could be replaced by titanium dioxide prepared by the present invention.

TABLE 3

As described above, the impact-resistant core-shell emulsion polymer containing pores in the particles according to the present invention can minimize the problems caused by using titanium dioxide alone, while reducing the cost of PVC molded articles, while also reducing the impact resistance and extrusion. It has the effect of maintaining injection workability and whiteness (color) more than the existing physical properties.

Claims (5)

In the method for producing an impact resistant core-shell emulsion polymer containing pores in the particles, (a) adding alkali monomers, ethylenically unsaturated monomers and crosslinking agents to seed particles prepared by polymerizing ethylenically unsaturated monomers, emulsifiers and radical initiators, and optionally acid equivalents, to prepare alkali swellable particles by emulsion polymerization; (b) reacting the swellable particles with an acid monomer of 0.1-20% by weight, 99.85-75% by weight of relatively low Tg, and 0.05-5% by weight of a crosslinking agent to prepare an elastomeric rubbery polymer ; (c) neutralizing the elastomeric rubbery polymer to a pH in the range of 7 to 12; (d) In the neutralized elastomeric rubber-like polymer, a first supply tank is filled with an alkyl (meth) acrylate having a relatively low Tg as a rubber-forming monomer, and a crosslinking agent, and is connected in parallel with the first supply tank. Preparing an interlayer copolymer by supplying a chain regulator and an alkyl methacrylate having a relatively high Tg, which is a hard shell forming monomer, to emulsion polymerization by a continuous composition change addition method; And (e) forming a hard skin polymer composed of an acrylic monomer having a relatively high Tg in the interlayer copolymer, The particle size of the final emulsion polymer is 0.15 to 0.4 microns, the diameter of a single pore after drying is 0.05 to 0.2 microns, the acid monomer contained in the alkali swellable particles is 15 to 40% by weight, the glass transition temperature of the elastomeric rubber polymer Is less than -20 ° C, the glass transition temperature of the interlayer copolymer is 0 to 40 ° C, and 40 to 75% by weight of alkyl acrylate having a relatively low Tg relative to the interpolymer forming monomer mixture, and a relatively high Tg. A method for producing a core-shell emulsion polymer, characterized in that the alkyl methacrylate is 20 to 60% by weight and the crosslinking agent is 0 to 5% by weight. The method of claim 1, wherein the crosslinking agent is aryl methacrylate, ethylene glycol dimethacrylate, 1,3-butanediol dimethacrylate, 1,4-butanediol dimethacrylate, 1,6-hexanediol dimethacrylate At least one selected from the group consisting of relate, 1,4-butanediol diacrylate, and 1,6-hexanediol diacrylate. The acid monomer of claim 1, wherein the acid monomer is selected from acrylic acid, methacrylic acid, itaconic acid, maleic acid or anhydride thereof, and the amount used is 15 to 40% by weight of the alkali-swellable polymer-forming monomer mixture including a seed. Process for preparing core-shell emulsion polymers. The method according to claim 1, wherein the alkali swellable polymer polymer is 5 to 30% by weight, 40 to 70% by weight of the elastomeric rubber polymer, 10 to 20% by weight of the interlayer copolymer and 15 to 30% of the hard shell polymer, based on the total mixture. Method for producing a core-shell emulsion polymer, characterized in that the weight%. The method of claim 1, wherein the alkali swellable polymer particles are finely flocculated with a flocculant.