JP2774300B2 - Foamable polymer emulsion composition - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to a novel foamable polymer emulsion composition. More specifically, the present invention provides hollow polymer particles that are useful as, for example, a pigment component for paper coating or a pigment component for various coatings, are lightweight and well scatter visible light, and have good opacity. It relates to a foamable polymer emulsion which can be easily provided.

2. Description of the Related Art Conventionally, organic pigments are widely used as pigment components for paper coating and pigment components for various paints, for example, since they have characteristics of being lightweight and thermoplastic compared to inorganic pigments. Have been. And in such applications, for the purpose of further improving the lightness and opacity,
In recent years, hollowing out the inside of particles has been performed. It is also known that, for particles whose diameter is on the order of the wavelength of visible light, hollowing the interior can further enhance the scattering effect of visible light and improve opacity.

As a method for producing such hollow particles, for example, (1) polymer particles comprising an alkali-soluble core portion and a shell portion covering the same are impregnated with a volatile alkali such as ammonia to swell the core portion. A method of obtaining hollow particles by swelling (JP-A-56-32513). (2) A monomer mixture having a solubility parameter different from the polymer by 0.1 or more in the presence of predetermined polymer particles. Method for obtaining hollow particles by polymerization (Japanese Patent Laid-Open No. 61-62)
No. 510) and (3) polymerizing a monomer mixture in the presence of a non-polymerizable solvent to form a polymer particle containing a solvent by utilizing phase separation of the solvent inside the polymer particle. A method of producing hollow particles by distilling off the solvent and then distilling off the solvent (JP-B-47-25862, JP-A-61-66710, JP-A-62-127336, JP-A-63-135409) and the like. Has been proposed.

However, in the method (1), since a relatively large amount of ammonia or the like must be used, there is a problem of environmental pollution due to generation of an irritating odor, as well as permeability of volatile alkali and extensibility of a shell part polymer. However, there is a drawback that a polymer design in consideration of the above is necessary, and the operation for that is inevitably complicated. Several methods (Japanese Patent Application Laid-Open Nos. 60-69103 and 61-185505) have been proposed for the purpose of remedying such disadvantages, but any method can provide satisfactory results. The fact is that is not obtained.

In the method (2), hollow particles are formed, although not necessarily clear, due to a change in density when a monomer is converted into a polymer. Has the fatal drawback of having certain limitations.

On the other hand, in the method (3), although the size of the hollow hole can be controlled by the amount of the solvent with respect to the polymer monomer, if the hollow hole is to be enlarged, a large amount of solvent corresponding to the amount is required. However, there is a disadvantage that the production process is complicated and the production cost is inevitably increased by distilling off the solvent.

On the other hand, utilizing the volume expansion when the liquid is vaporized, to create pores inside the particles, as a technology applying a so-called physical foaming method, 0.05 to 10μ containing a volatile organic compound
Also known is a method for obtaining expandable small resin particles having a particle size of m (JP-A-60-252635). However, this method is for producing particles having a homogeneous cell structure, that is, a multi-cell structure, and does not provide a polymer particle having a single hollow pore as the object of the present invention. There is also known a method for producing thermoplastic polymer particles having a liquid foaming agent of 1 to 50 μm by suspension polymerization (Japanese Patent Publication No. Sho 42-2652).
No. 4), it is difficult to produce polymer particles of 1 μm or less in good yield by this method, and it is difficult to physically foam polymer particles of 1 μm or less only by heating. It is.

Problems to be Solved by the Invention The present invention overcomes the drawbacks of such a conventional method for producing hollow polymer particles, and provides a hollow polymer particle having a particle size in a range that is lightweight and effective for scattering light. To provide a foamable polymer emulsion composition that can be easily provided without troubles caused by evaporation of a large amount of solvent or generation of odor, and without the problem of difficulty in controlling the size of hollow holes. It was made for the purpose.

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to achieve the above object, and as a result, the physical foaming method has set the size of the hollow hole by appropriately setting the amount of the liquid to be vaporized. Focusing on the fact that it can be arbitrarily controlled, a weight-average particle diameter obtained by incorporating a physical blowing agent having a specific boiling point at a predetermined ratio in at least the core portion of the specific core / shell polymer particles is 0.05%. It has been found that the purpose can be achieved by an emulsion composition containing foamable polymer particles of 1 μm, and the present invention has been completed based on this finding.

That is, the present invention relates to a shell portion 99 to 25 composed of a crosslinked polymer containing 1 to 75% by weight of a core portion substantially composed of a non-crosslinked polymer and 0.3% to less than 30% by weight of a crosslinkable monomer unit. Weight-average particle diameter of 0.05 to 1.1 μm comprising core / shell type polymer particles constituted by weight% and a physical blowing agent having a boiling point of 95 ° C. or less impregnated in the core portion or the core portion and the shell portion. The present invention provides an expandable polymer emulsion composition characterized by containing the expandable polymer particles of (1).

 Hereinafter, the present invention will be described in detail.

The core portion of the core / shell type polymer particles used in the composition of the present invention is composed of a substantially non-crosslinked polymer (A). Examples of the polymer (A) include aromatic vinyl compounds and acrylates. Alternatively, those obtained by polymerizing at least one polymerizable monomer selected from methacrylates, vinyl esters, vinyl ethers, and other unsaturated monomers can be used.

Examples of the aromatic vinyl compound include styrene, o
-Methylstilne, m-methylstyrene, p-methylstyrene, ethylstyrene, ar-vinyl xylen, ar-
Styrene derivatives such as chlorostyrene, ar-bromostyrene, vinylbenzyl chloride, p-tert-butylstyrene, and acrylates or methacrylates such as methyl-, ethyl-, propyl-, n-butyl, isobutyl-, Each acrylate or methacrylate such as butyl-, n-amyl-, isoamylhexyl-, octyl-, nonyl-, decyl-, dodecyl-, octadecyl-, cyclohexyl-, phenyl-, and benzyl- is a vinyl ester. Vinyl acetate, vinyl butyrate, vinyl stearate, vinyl laurate, vinyl myristate, vinyl propionate, vinyl versatate, etc., and examples of vinyl ethers include methyl, ethyl, propyl, butyl, amyl, hexyl Vinyl ethers having any alkyl group.

Further, as other unsaturated monomers, for example, vinyl cyanides such as acrylonitrile and methacrylonitrile, vinyl chloride, vinyl bromide, vinyl fluoride, vinylidene fluoride, vinyl halides such as vinylidene chloride, maleic acid, Fumaric acid, unsaturated dibasic acid alkyl esters such as monoalkyl esters such as itaconic acid, olefins such as ethylene, glycidyl compounds such as glycidyl (meth) acrylate and methyl glycidyl (meth) acrylate, acrylamide,
Amides such as methacrylamide and their N-methylol compounds and alkoxy compounds, silicon-containing α, β-ethylenically unsaturated monomers such as vinyltrichlorosilane and vinyltriethoxysilane, β-hydroxyacrylate and β-hydroxy Α, β-unsaturated monomers containing hydrogen groups such as methacrylate, α, β-ethylenically unsaturated monomers such as acrylic acid, methacrylic acid, itaconic acid, citraconic acid, maleic acid, fumaric acid, vinylbenzoic acid, and cinnamic acid Examples include saturated carboxylic acids, unsaturated acids such as vinyl sulfonic acid and styrene sulfonic acid, and basic monomers such as vinyl pyridine, dimethylaminoethyl acrylate, dimethylaminoethyl methacrylate, diethylaminoethyl acrylate, and diethylaminoethyl methacrylate. .

Each of these monomers may be used alone, or 2
A combination of more than one species may be used. Further, since the polymer (A) forming the core portion is a substantially non-crosslinked polymer, it is not preferable to include a crosslinkable monomer unit, but it is controlled in a region where the molecular weight is appropriately low. However, if the polymer is a substantially non-crosslinkable polymer, a crosslinkable monomer unit may be contained as required. For example, for the purpose of imparting flexibility, a diene monomer unit such as butadiene, isoprene and chloroprene can be contained.

When the polymer (A) forming the core portion is substantially crosslinked, the formation of hollow holes is incomplete. The degree of crosslinking of the polymer can be related to the swelling index and the solvent-insoluble content. In general, since the latter value for measuring the weight of the dry gel is more reproducible than the former value for measuring the weight of the wet gel, it is convenient to express the degree of cross-linking with toluene-insoluble matter for convenience. is there. In the present invention, "substantially non-crosslinked" means that the toluene-insoluble matter is less than 15% by weight. Further, it is advantageous that the molecular weight of the polymer (A) forming the core is low, and it is preferably 190,000 or less. This molecular weight can be measured by a viscosity method described later.

On the other hand, the shell portion is made of a polymer (B) containing 0.3% by weight or more and 30% by weight or less of a crosslinkable monomer unit,
Examples of the monomer forming the polymerizable monomer unit of the polymer (B) include those exemplified as the polymer monomer used for the polymer (A) forming the core. . The monomers may be used alone or in combination of two or more.

Further, as a monomer forming a crosslinkable monomer unit,
Compounds having at least two polymerizable unsaturated bonds in the molecule can be mentioned, such as ethylene glycol dimethacrylate, 1,3-butylene glycol dimethacrylate, 1,4-butylene glycol dimethacrylate, Propylene glycol dimethacrylate, divinylbenzene, diallyl phthalate, ethylene glycol diacrylate, 1,3-butylene glycol diacrylate, bis (4-acryloxypolyethoxyphenyl) propane, 1,5-pentanediol diacrylate, neopentyl glycol diacrylate Acrylate, 1,6
-Hexanediol diacrylate, diethylene glycol diacrylate, triethylene glycol diacrylate, tetraethylene glycol diacrylate, other polyethylene glycol diacrylate, polypropylene glycol diacrylate, pentaerythritol triacrylate, trimethylolpropane triacrylate, tetramethylol methane tetraacrylate, Allyl methacrylate and the like can be mentioned. In addition,
Diene monomers such as butadiene, chloroprene and isoprene, and polyene monomers having three or more double bonds such as trivinylbenzene and triallyl isocyanurate can of course be used as crosslinkable monomers. it can. These crosslinkable monomers may be used alone or in combination of two or more.

The content of the crosslinking monomer unit in the polymer (B) forming the shell portion is in the range of 0.3% by weight to less than 30% by weight, preferably 0.3% to 10% by weight, more preferably 0.3% to 6% by weight. It is necessary to be in. If the amount is less than 0.3% by weight, the polymer constituting the outer layer of the particles is not sufficiently crosslinked, so that there is a possibility that a sufficiently large hollow hole is not formed at the time of foaming. It is difficult to make the foaming agent hollow by vaporization. As a standard of the preferable range of the degree of crosslinking, the polymer (B) in the shell portion is conveniently used.
Can be expressed by the toluene-insoluble content of the core / shell type polymer particles, and this value is preferably 15% by weight or more.

In the present invention, the polymer (A) forming the core portion
And the weight ratio of the polymer forming the shell portion (B) to 1:99
To 75:25, preferably 2:98 to 50:50, more preferably 10:90 to 43:57. If the proportion of the polymer (A) is less than this, it is difficult to form hollow pores, and if it is more than this, physical destruction occurs during foaming, and furthermore, the mechanical properties of the finally obtained hollow particles are reduced. It is not preferable because the strength is inferior.

The emulsion composition of the present invention contains expandable polymer particles in which such a core / shell type polymer particle contains a physical blowing agent. Those having a boiling point of 95 ° C. or less at atmospheric pressure are used. Such materials include, for example, aliphatic hydrocarbons such as titanium, ethylene, propene, propane, butane, butadiene, pentane, hexane, cyclohexane, isobutene, neopentane, methyl chloride, methylene chloride, ethyl chloride, chloroform, and carbon tetrachloride. , Chlorinated hydrocarbons such as trichloroethylene, fluorinated chlorinated hydrocarbons such as trichlorofluoromethane, dichlorodifluoromethane, dichlorofluoromethane, chlorodifluoromethane, trichlorotrifluoroethane, aromatic hydrocarbons such as benzene, butadiene, acrylonitrile, etc. And the like. Among them, those having a boiling point of 90 ° C. or less under atmospheric pressure are preferable.
Each of these may be used alone or in combination of two or more.

It may be preferable that the boiling point of the physical blowing agent is lower than the glass transition temperature of the polymer (B). Since the glass transition temperature of the polymer differs depending on its composition, molecular weight, molecular weight distribution, and the like, it should be measured.For example, it can be measured using a viscoelasticity measuring device, a differential thermal analyzer, or the like. An equation for calculating the glass transition temperature of the copolymer is known, and an approximate value can be obtained by calculation using the following equation.

1 / Tg = Σ (Wi / Tgi) where Tg is the glass transition temperature of the copolymer, Tgi is the glass transition temperature of the homopolymer of the i-th component constituting the copolymer, and Wi is the glass transition temperature of the copolymer. It is a weight fraction of the i component.

The amount of the physical blowing agent is generally selected in the range of 1 to 300 parts by weight, preferably 5 to 250 parts by weight, per 100 parts by weight of the core / shell type polymer particles. If this amount is less than 1 part by weight, the polymer particles hardly expand, and if it exceeds 300 parts by weight, the polymer particles expand temporarily and well immediately after foaming, but the temperature at which the polymer particles are placed is low. Depending on the pressure, pressure, or type of physical blowing agent, it is often deformed unevenly and deformed, or conversely shrinks, and it is necessary to increase the hollow pore diameter of the polymer particles for that amount Can not.

Also, the type and amount of this physical foaming agent, for example,
It is appropriately selected depending on the particle size of the polymer particles, the composition and molecular weight of the polymers (A) and (B), the proportion of the toluene-insoluble component, the outer diameter and the size of the desired hollow polymer particles. It is desirable.

In the composition of the present invention, it is necessary that the physical foaming agent is contained at least in the core portion. If the physical foaming agent is not contained in the core portion, a hollow body will not be formed when foamed. In some cases, it may be contained in both the core portion and the shell portion. In this case, it is advantageous that the polymer (A) in the core portion or the vicinity thereof has a higher concentration than the polymer (B) in the shell portion. From this point as well, in the present invention, the polymer (A) needs to be substantially non-crosslinked, and the polymer (B) needs to be crosslinked. Further, it is desirable that (A) has a physical foaming agent and a solubility parameter closer to that of (B).

In the composition of the present invention, the weight average particle diameter of the expandable polymer particles obtained by impregnating the core / shell type polymer particles with the physical blowing agent needs to be in the range of 0.05 to 1.0 μm. It is. If the particle size is less than 0.05 μm, the foaming properties and optical performance are poor, and if it exceeds 1.0 μm, the optical performance is reduced.

The emulsion composition of the present invention is an aqueous emulsion containing such expandable polymer particles. The solid content concentration is not particularly limited, but is usually 5 to 70% by weight, preferably 10 to 55% by weight. It is selected in the range of weight%.

The core / shell particles in the composition of the present invention may be cationic, anionic or amphoteric in terms of colloidal stability, and are appropriately selected depending on the application.

Further, the emulsion composition of the present invention may contain various additives such as an emulsifier, a stabilizer, and a polymerization initiator during the emulsion polymerization described below, and the range not detracting from the object of the present invention. In, if desired, a bactericide,
A preservative, a viscosity modifier and the like can be contained.

As a method for producing the emulsion composition of the present invention, for example, first, core / shell type polymer particles are produced,
Then, a method of impregnating the polymer particles with a physical blowing agent, or when producing the core / shell type polymer particles,
When producing the polymer forming the core or the polymer forming the shell, a method of coexisting a physical foaming agent can be used.

The order of producing the core and the shell is not particularly limited, but a method of producing the polymer forming the core and then producing the polymer forming the shell is generally used. However, in some cases, the polymer forming the shell is first produced, and then the polymer forming the core is produced,
It can also be manufactured by a so-called phase inversion method (phase inversion method). However, in the present invention, since the polymer forming the shell has a crosslinked structure, it is preferable to produce the core and the shell in this order rather than the phase inversion method.

Next, as a specific example, a case where the core and the shell are manufactured in this order will be described. First, a polymer (A) forming the core is selected from the above-mentioned monomers by selecting an appropriate polymer and emulsifying the polymer. Produced by polymerization. That is, in an aqueous medium,
Conventionally, various additives conventionally used in emulsion polymerization, for example, a surfactant, a dispersant, a colloid protective agent, a polymerization initiator, 1 to 75 parts by weight of a polymerizable monomer added to seed particles,
This is done by heating with stirring. In this case, if necessary, the reaction may be carried out in the presence of a physical foaming agent. As a method of coexisting a physical foaming agent, a method of using seed particles which have been swollen in advance with a physical foaming agent, a method of mixing the seed particles with a polymerizable monomer, and subjecting to emulsion polymerization are employed.

When forming the polymer of the core portion, it is recommended to carry out emulsion polymerization in the presence of a conventionally known chain transfer agent in order to reduce the molecular weight of the polymer. These chain transfer agents are not particularly limited, and can be appropriately selected from those commonly used for controlling the molecular weight of ordinary weight reaction. The chain transfer constant of this chain transfer agent depends on the type of monomer used, polymerization conditions, and the like. However, even a commonly used organic solvent having a high chain transfer constant has a high chain transfer constant. It can be used as a transfer agent. This chain transfer constant is determined to be 0.1 based on the polymerization of styrene.
5 × 10 ^-4 or more is appropriate. Some of these chain transfer agents are described in the Polymer Handbook.
k) "(published by John Wheely and Sons, Inc.). Examples of the chain transfer agent include mercaptans having an alkyl group having 1 to 30 carbon atoms, such as propyl mercaptan, butyl mercaptan, and dodecyl mercaptan, and octyl thioglycolate, thioglycolic acid, and diphenyl sulfides having 1 to 30 carbon atoms. Examples thereof include organic sulfur compounds, halogenated hydrocarbons having 1 to 20 carbon atoms such as carbon tetrachloride, carbon tetrabromide, and bromotrichloromethane. These chain transfer agents may be used alone or in combination of two or more.

This emulsion polymerization can be carried out in the presence of a conventionally known surfactant. For example, anionic, cationic, nonionic, amphoteric, reactive surfactants and oligosoaps are used. These surfactants may be used alone or in combination of two or more, but usually, anionic and nonionic surfactants are preferably used from the viewpoint of polymerization stability. As the anionic surfactant, for example, an alkali metal salt of alkyl benzene sulfonic acid, an alkali metal salt of alkyl sulfate, an alkali metal salt of polyoxyethylene alkyl phenol sulfate, an alkali metal salt of alkyl diphenyl ether disulfonate, an alkali metal salt of dialkyl sulfosuccinic acid and the like are used. Can be. As the nonionic surfactant, for example, polyoxyethylene alkylphenol ether, polyoxyethylene alkyl ether, polyoxyethylene higher fatty acid ester, ethylene oxide-propylene oxide block copolymer and the like can be used. Further, an acrylic water-soluble oligomer may be used in combination with the anionic surfactant. Further, a water-soluble polymer compound having an action as a colloid protective agent such as polyvinyl alcohol, hydroxyethylcellulose, hydroxypropylcellulose and the like can be used if necessary. As these surfactants and water-soluble polymer compounds increase in use amount, the water resistance of the obtained polymer may decrease, so that the use amount is preferably small, but at least the polymerization stability is low. It is preferable to use the minimum amount necessary to maintain the mechanical stability and the chemical stability of the product. This amount is usually
It is selected in the range of 0.1 to 7 parts by weight based on 100 parts by weight.

As the polymerization initiator, a compound that generates a radical at a temperature of about 0 to 150 ° C is used. As the polymerization initiator, a water-soluble one is mainly used, but an oil-soluble one may be used. Representative polymerization initiators include ammonium persulfate, sodium persulfate, water-soluble persulfates such as potassium persulfate, inorganic peroxides such as hydrogen peroxide, benzoyl peroxide, cumene hydroperoxide, lauroyl peroxide, Organic peroxides such as tert-butyl peroxide and tert-butylperoxy-2-ethylhexanoate; and azo compounds such as azobisisobutyronitrile are exemplified. In addition, a so-called redox-based initiator that combines the peroxide with a reducing agent to generate a radical in the presence of a trace amount of metal ion can also be used. Examples of this redox type include hydrogen peroxide-ferrous chloride type, cumene hydroperoxide-sodium ascorbate type and the like. The amount of the polymerization initiator to be used is usually selected in the range of 0.1 to 2.5 parts by weight based on 100 parts by weight of the total amount of the monomers. Further, the polymerization initiator may be used alone,
Two or more kinds may be used in combination. In the present invention, the above-mentioned various monomers or a monomer mixture containing a physical foaming agent as necessary may be charged all at once into the polymerization reactor, or may be divided stepwise, or It may be added continuously. Depending on the manner in which such a monomer is added, the polymer may form a layered structure or the composition may change continuously.

The polymerization reaction is usually carried out at a temperature in the range of 0 to 130 ° C., preferably 30 to 100 ° C., under conditions in which a sufficient amount of radicals are supplied from the polymerization initiator system to carry out the polymerization reaction. The polymerization time is not particularly limited, and is usually from 1 to 24.
Hours, preferably 1 to 6 hours.

On the other hand, the formation of the shell part is more than 0.3% by weight and 30% by weight.
A monomer mixture containing less than a crosslinkable monomer, in the presence of the core particles obtained as described above, if necessary, by performing the same emulsion polymerization method as the core in the presence of a physical blowing agent Can be. The polymerizable monomer used at this time can be appropriately selected from those exemplified as the polymerizable monomer for producing the polymer (A) of the core portion, and can be used. The crosslinkable monomer used in combination with the polymerizable monomer can be appropriately selected from the crosslinkable monomers described above.

The amount of these monomers to be used is selected in the range of 25 to 99% by weight based on the total amount of the polymer (A) forming the coexisting core portion. Examples of the method of using a physical foaming agent in this emulsion polymerization include a method of using a swelling core impregnated with a physical foaming agent, a method of mixing a monomer and a physical foaming agent, and subjecting the mixture to a reaction of emulsion polymerization. A method of providing the system can be adopted. Further, if the core contains a desired amount of a physical blowing agent during the production, when forming the shell portion,
No additional physical blowing agent is required. As specific conditions for the emulsion polymerization, the conditions for producing the core can be employed as they are.

The polymer (B) in the shell portion can control the size of the hollow pores and the mechanical properties of the hollow polymer particles by setting the degree of crosslinking in an appropriate range. As a standard of the preferable range of the degree of crosslinking, it can be conveniently represented by the toluene-insoluble content of the core / shell type polymer particles instead of the polymer (B) in the shell portion, and this value is 15% by weight or more. Is preferred. If the toluene-insoluble content is less than 15% by weight, the effect of trapping the physical foaming agent when it is vaporized becomes insufficient, so that the gas escapes and the pore diameter does not grow.

In the production of the polymer (B) of the shell portion, it is necessary to form a substantially cross-linked polymer. Therefore, it is desirable not to use a chain transfer agent that suppresses cross-linking. And a small amount of a chain transfer agent may be used, if desired, for the purpose of adjusting the concentration and improving the rate of volume increase under mild conditions.

The solid content concentration during the emulsion polymerization is not particularly limited, but is usually 5 to 5 from the viewpoints of economy, stability and fluidity.
It is selected in the range of 70% by weight. In particular, the foamable emulsion of the present invention preferably contains 10 to 55% by weight from the viewpoint of containing a physical foaming agent and foaming in the next step.

The core / shell type particles in the present invention may be cationic, anionic or amphoteric in terms of colloidal stability, and are appropriately selected according to the application.
Such a colloidal property can be imparted by using a surfactant or a polymerization initiator having a corresponding substance, but is easily achieved by appropriately selecting a polymerizable monomer. You. That is, when it is desired to impart cationicity, a basic monomer is used.When it is desired to provide anionic property, a monomer having a carboxyl group or a sulfonic acid group is used. It may be used together.

In the present invention, the polymers (A) and (B) generally have different solubility parameters. In general emulsion polymerization, the larger the solubility parameter, that is, the higher the polarity, the higher the probability of phase separation on the particle surface. Therefore, when determining the production order of (A) and (B), in addition to the weight ratio of the polymer, the presence or absence of the crosslinking agent,
It is desirable to determine in consideration of such points.

The foamable polymer and the emulsion composition of the present invention can be obtained by emulsion polymerization in the presence of a physical foaming agent during the production of the core portion and the shell portion. After production, it can also be produced by impregnating it with a physical blowing agent. In such a case, a method is generally employed in which a physical foaming agent is added to the polymer emulsion, and the mixture is impregnated with stirring at a predetermined temperature and pressure.

The specific operation method at this time is not particularly limited, and after mixing a physical foaming agent with the polymer emulsion, heating, pressurizing, or the like may be performed. May be. As a method of mixing the polymer emulsion and the physical foaming agent, the physical foaming agent may be added as it is, or may be added after being dispersed in water.
In this case, in order to impregnate the water dispersion more efficiently, the dispersion diameter of the physical foaming agent in advance using an ultrasonic homogenizer, a homomixer, or the like, a particle diameter of 4 times or less of the polymer particles, Preferably, it is advantageous to set it to 1 or less. At this time, a surfactant may be added to stabilize the particles of the physical blowing agent. In addition, in order to prevent early coalescence of oil droplets of the physical foaming agent dispersed in water and to further stabilize the oil droplets, the solubility in water of 0.
It is advisable to add a small amount of the poorly water-soluble compound of 1% by weight or less to the physical blowing agent in advance. It is also effective to mix the polymer emulsion and the physical blowing agent and then subject the mixture to ultrasonic treatment. In this case, the obstacle of lowering the solid content is eliminated.

The temperature at which the physical foaming agent is impregnated is not particularly limited, but is usually in the range of 30 to 150 ° C, preferably 30 to 130 ° C. However, as long as the absorption rate is not impaired, a lower temperature is advantageous because fusion and aggregation of the polymer particles do not occur. In addition, when foaming is performed immediately after impregnation with a physical foaming agent, a temperature suitable for foaming can be considered. There is no particular limitation on the time for absorption. The time required for a sufficient amount of the physical blowing agent to penetrate into the polymer particles of the polymer emulsion depends on the type of the physical blowing agent, the solubility and the diameter of oil droplets, the composition and the particle size of the polymer particles. It depends on temperature, pressure, etc., and it takes about several minutes for easy absorption and several tens of hours for poor absorption, but it can usually be absorbed in about 20 minutes to 5 hours. It is not preferable to make it longer than necessary. There is no particular limitation on the absorption pressure. The pressure varies depending on the type of the physical foaming agent to be used, depending on the absorption temperature and the like. In consideration of foaming, if desired, the pressure may be increased by an inert gas or the mixture itself may be increased.

As the physical foaming agent, one having a certain degree of compatibility with the polymer particles of the polymer emulsion is used, and the balance between ease of penetration into the polymer particles and swelling of the polymer particles is improved. It is advantageous from the point of view. That is, when the compatibility is extremely small, since the physical blowing agent hardly penetrates into the polymer particles, the power to expand the polymer particles tends to be inferior, while when the compatibility is too high, However, the vaporization power for expanding the particles tends to be low.

As described above, the larger the solubility parameter of the polymer (A) and the polymer (B) is, the more easily the polymer (A) and the polymer (B) appear on the surface.
It is common practice to use a physical foaming agent having a small solubility parameter to increase the swelling property of the core portion.

The foamable polymer emulsion composition of the present invention can easily obtain hollow polymer particles by shifting from a state in which the physical foaming agent is heated to a boiling point or higher to a low pressure region. The temperature and pressure of the foamable polymer emulsion at the time of physical foaming by transferring the foamable polymer emulsion to a low pressure range have an important influence on the degree of foaming. This temperature must be above the boiling point of the physical blowing agent. At temperatures lower than this, almost no foamed particles can be obtained. At this temperature, the particles, especially the polymer in the shell portion, must have sufficient deformation fluidity, but furthermore, the gas permeability is so large that the foaming pressure can be linked to the enlargement of the particles. It is important to have low and tensile strength to resist pressure. Therefore, the higher the temperature of the emulsion is, the better it is not. It is preferable that the temperature is not more than 50 ° C. higher than the boiling point of the physical blowing agent. The pressure of the emulsion is not particularly limited. However, since the emulsion is heated to a temperature equal to or higher than the boiling point of the physical foaming agent, it usually exceeds its atmospheric pressure even by its own pressure. Although this self-pressure may be used, particles having a higher foaming rate are more easily obtained when the pressure is maintained at a higher pressure. In addition, since the pressure is closely related to the transition speed when shifting to the low pressure side, it is necessary to select from this viewpoint. Normally used pressure is 1 to 50 kg / cm ² (gauge pressure).

The heated and pressurized polymer emulsion is transferred to a low pressure region to expand the polymer particles. The atmosphere in the low pressure region may be a gas or a liquid. When it is a gas, it is preferably an inert gas such as nitrogen, and when it is a liquid, it is preferably water.
The temperature in the low pressure range is appropriately selected depending on the composition of the polymer particles, the type and amount of the physical blowing agent contained in the particles, and is usually equal to or lower than the temperature of the polymer emulsion.
However, when the polymer particles absorb a large amount of the physical blowing agent, the physical blowing agent remains considerably in the polymer particles even after the migration, so that the polymer emulsion is further vaporized. Often, the temperature is shifted to a low pressure region or higher.

When most of the physical blowing agent has been removed and the pressure inside the particles can no longer be maintained high, the temperature of the emulsion is preferably below the glass transition temperature of the polymer particles. Further, it is advantageous that the removal of the physical blowing agent is performed under reduced pressure.

The transfer of the polymer emulsion from the high-pressure region to the low-pressure region may be performed by reducing the pressure of the container as it is, but usually, a single hole, a multi-hole, or a slit shape, and other flow rates and pressure changes during the transfer can be controlled. It can be performed from the shape moving port.

The foamed particles obtained in this way have an original volume of 20 to
It expands at a volume increase rate of 1000%, forming an almost single hollow hole.

Although the mechanism by which the hollow pores are formed inside the polymer particles is not necessarily clear, the polymer particles having a substantially non-crosslinked polymer as a core portion and a crosslinked polymer as a shell portion are foamed. It is considered that the minute gas generated concentrates near the core to form a hollow inside the particle.

At this time, if the polymer particles are composed of a homogenous polymer instead of a core / shell type structure, a foam may be formed, and sometimes a vaporized physical foaming agent may escape to the outside as it is, resulting in a hollow hole. Cannot be formed. In the present invention, since the core has a non-crosslinked core and a crosslinked shell structure, the core may contain a physical foaming agent at a higher concentration than the shell. It is considered that the shell of the crosslinked structure temporarily suppresses the escape of gas, and a hollow hole is formed therebetween.

The hollow polymer particles may be used as an emulsion by removing the remaining physical blowing agent, or may be used as a powder through a spray drying step or the like.

Effect of the Invention The expandable polymer emulsion composition of the present invention is a composition of the polymer constituting the expandable polymer particles, the degree of crosslinking of the shell,
By appropriately selecting the type, composition, amount, and the like of the physical foaming agent, or at the time of foaming the foamable polymer particles, the temperature and pressure of the composition, and even the temperature and pressure in the low pressure range, pass through at the time of transition. By appropriately selecting the shape of the nozzle and the slide, the passing speed, the temperature gradient, the pressure gradient, the post-treatment conditions, and the like, hollow polymer particles having a desired hollow pore size can be easily provided, and It has excellent features such as requiring a smaller amount of a physical foaming agent with respect to the volume of the pores than the prior art, and having no odor problem.

The hollow polymer particles obtained from the expandable polymer emulsion composition of the present invention are lightweight and have a high ability to scatter visible light. In the field of paints where
Some of them can be used instead. In the papermaking field, an inorganic pigment such as talc is used as an internal additive. However, the use of the cationic hollow polymer obtained from the composition of the present invention provides excellent performance in such fields as light weight and excellent yield. Is shown. Furthermore, in order to improve printability and smoothness of paper and paperboard, a pigment was applied to the surface,
So-called coated papers are produced, and in order to further improve the performance, the hollow polymer particles can be used, and the coated papers have excellent gloss, whiteness, opacity, rigidity, lightness, etc. It will be. In addition, it can be used as an auxiliary for dyeing leather, or as an additive to adhesives, pressure-sensitive adhesives, primers, inks and the like.

EXAMPLES Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.

 In addition, the measuring method and evaluation of each characteristic are as follows.

(1) Toluene-insoluble content The polymer emulsion is dried at a temperature higher than the glass transition temperature of the polymer, usually at 120 ° C for 90 minutes, and further at 160 ° C for 3 minutes. 50 ml of toluene was added to 1.00 g of the film thus obtained, and the mixture was shaken for 5 hours, followed by filtration with 325 mesh stainless steel. The solid is dried at 120 ° C. for 50 minutes and the weight (b) is measured. The toluene insoluble content is determined by the following equation.

Toluene-insoluble matter (% by weight) = 100b (2) Weight-average particle diameter From a transmission electron micrograph, a 25,000-fold photograph was projected and the diameter of 300 to 1000 particles was measured.

(3) A toluene-soluble solution of the polymer (A) having a number-average molecular weight of 0.1 to 0.8% by weight was prepared, and the intrinsic viscosity at 30 ° C. was measured using an Ubbelohde viscometer.

η = 11 × 10 ⁻³ [Mn] ^0.725 where η represents the intrinsic viscosity and Mn represents the number average molecular weight.

(4) Volume increase rate (ΔV) ΔV = 100 × (V2−V1) / V1 Here, V1 represents the particle volume before foaming.

 V2 represents the particle volume after foaming.

Example 1 Into a separable flask having a capacity of 1, 100 parts by weight of distilled water, 0.2 part by weight of sodium dodecylbenzenesulfonate, 0.5 part by weight of potassium persulfate, and 0.1 part by weight of sodium bicarbonate were added and dissolved. Subsequently, 0.4 part by weight of a 350-g particle size styrene / acrylic acid copolymer latex made from 96 parts by weight of styrene and 4 parts by weight of acrylic acid was added, and the mixture was heated to 70 ° C. while stirring under a stream of nitrogen gas. A monomer mixture consisting of 78.6 parts by weight, 4 parts by weight of t-dodecyl mercaptan, 15 parts by weight of butyl acrylate and 2 parts by weight of methacrylic acid was fed to the separable flask in 5 hours, and polymerization was continued for 1 hour. Next, 0.2 parts by weight of potassium persulfate and 0.05 parts by weight of sodium bicarbonate were dissolved in 20 parts by weight of distilled water, and the resulting mixture was put into a polymerization vessel, and kept at 75 ° C. for 2 hours to obtain polymer particles having a particle size of 0.22 μm. Emulsion (I) was obtained.

The intrinsic viscosity of the emulsion-soluble portion of the polymer particles is 7.
It was 6 ml / g, and the number average molecular weight of the toluene-soluble component calculated by calculation was 8,250.

Next, in a separable flask, 100 parts by weight of distilled water,
0.15 parts by weight of sodium dodecylbenzenesulfonate, 0.5 parts by weight of potassium persulfate, 0.1% by weight of sodium bicarbonate and 12.5 parts by weight of the polymer emulsion (I) in terms of solid content
Weight parts were added. The flask was replaced with nitrogen gas, and the temperature was raised to 70 ° C. while stirring. 3/5 of a monomer mixture consisting of 50.5 parts by weight of styrene, 7.0 parts by weight of acrylonitrile, 25 parts by weight of methyl methacrylate, and 4 parts by weight of methacrylic acid
5 was fed to the flask over 3 hours, at which point 1 part by weight of ethylene glycol dimethacrylate was added to the remaining mixed monomer, and the monomer feed was terminated by continuing to feed for another 2 hours. Thereafter, the temperature was maintained at 70 ° C. for 1 hour. Dissolve 0.2 parts by weight of potassium persulfate and 0.05 parts by weight of sodium bicarbonate in 20 parts by weight of distilled water, place them in a flask, and keep at 75 ° C. for 2 hours to obtain an emulsion of polymer particles having a particle diameter of 0.387 μm ( II). The solids concentration of this emulsion is
It was 40% by weight.

Next, 20 parts by weight of the thus-obtained copolymer emulsion (II) and 20 parts by weight of a mixture of pentane and cyclohexane (weight ratio 1/1) were placed in an autoclave and heated at 95 ° C. for 2 hours. Shake for hours. Next, after the temperature was raised to 130 ° C., the valve was opened, and spouted into warm water at 95 to 100 ° C., and stirring was continued for 30 minutes to remove most of the residual volatile organic compounds. The mixture was concentrated under reduced pressure of 30 mmHg under bubbling to obtain hollow polymer particles. Table 1 shows the results.

Examples 2 to 7 The procedure of Example 1 was repeated except that the composition of the monomer mixture used to produce the polymer emulsion (II) was changed as shown in Table 1. Polymer particles were prepared. Table 1 shows the results.

Comparative Examples 1 and 2 The procedure of Example 1 was repeated except that the composition of the monomer mixture used to produce the polymer emulsion (II) was changed as shown in Table 1. Polymer particles were prepared. Table 1 shows the results.

Example 8 Into a separable flask, 100 parts by weight of distilled water, 0.2 part by weight of sodium dodecylbenzenesulfonate, 0.5 part by weight of potassium persulfate, and 0.1 part by weight of sodium bicarbonate were added and dissolved. Next, a styrene / acrylic acid copolymer latex made from 96 parts by weight of styrene and 4 parts by weight of acrylic acid
Add 0.4 parts by weight and stir while stirring under a stream of nitrogen gas.
After the temperature was raised to 0 ° C., a monomer mixture consisting of 77.6 parts by weight of styrene, 5.0 parts by weight of t-dodecyl mercaptan, 15 parts by weight of butyl acrylate, and 2 parts by weight of methacrylic acid was fed into a separable flask for 5 hours, and further 1 hour. The polymerization was continued. Next, 0.2 parts by weight of potassium persulfate and 0.05 parts by weight of sodium bicarbonate are dissolved in 20 parts by weight of distilled water, and the resulting mixture is placed in a flask and kept at 75 ° C. for 2 hours to obtain polymer particles having a particle size of 0.22 μm. Emulsion (III) was obtained.

The intrinsic viscosity of the toluene soluble component of the polymer particles is 6.9 ml /
g, and the number average molecular weight of the toluene-soluble component calculated by calculation was 7,220.

Polymer emulsion (III) thus obtained
Is used as a solid content of 12.5 parts by weight, and as monomers, styrene 58.5 parts by weight, acrylonitrile 5 parts by weight,
Using 15 parts by weight of methyl methacrylate, 4 parts by weight of methacrylic acid, and 5 parts by weight of ethylene glycol dimethacrylate, a polymer emulsion (IV) was produced in the same manner as in the step of producing the polymer emulsion (II) in Example 1, Further, hollow polymer particles were prepared in the same manner as in Example 1.
Table 2 shows the results.

Examples 9 to 12 Except that the monomer composition shown in Table 2 was used in the preparation of the polymer emulsion (III) in Example 8, and the amount of t-dodecyl mercaptan was changed as shown in Table 2 A polymer emulsion (III) was produced in the same manner as in Example 8, then a polymer emulsion (IV) was produced, and hollow polymer particles were prepared therefrom. Table 2 shows the results.

Examples 13 to 17, Comparative Examples 3 and 4 Seven kinds of polymer emulsions (V) having the same composition but different particle diameters were produced according to the production steps of the polymer emulsion (I) of Example 1. did. That is, first,
7.5 parts by weight, 2 parts by weight, and 0.5 parts by weight of the styrene / acrylic acid copolymer latex used in Example 1 were used as seed latex, respectively, and polymerized to give particle diameters of 0.060 μm, 0.144 μm, and 0.205, respectively. A μm polymer emulsion was prepared. At this time, as the monomer mixture, 79.5% by weight of styrene, 3.5% by weight of t-dodecyl mercaptan, 15% by weight of butyl acrylate,
What consisted of 2% by weight of methacrylic acid was used.

Furthermore, using the emulsion obtained with the particle diameter of 0.144 μm 11 parts by weight, 6.8 parts by weight, 6.2 parts by weight, 4.3 parts by weight as a seed latex, the particle diameter under the same monomer mixture and polymerization conditions as described above. 0.261μm each,
Larger particles of 0.299 μm, 0.310 μm and 0.337 μm were produced.

Using the seven types of polymer emulsions thus obtained, polymerization was carried out in accordance with the production process of the polymer emulsion (II) of Example 1 to produce a polymer emulsion. Incidentally, the composition of the monomer, styrene, acrylonitrile, methyl methacrylate, methacrylic acid, ethylene glycol dimethacrylate, 63/8 by weight, respectively
/ 20/4/5, and the weight ratio (A) / (B) of the polymer (A) and the polymer (B) is 0.00
The monomer mixture was fed in the presence of the polymer emulsion (V) so as to be 5, 0.07, 0.20, 0.40, 0.60, 0.70, 0.93 to produce a polymer emulsion (VI). However, in the polymerization in this step, the amount of the polymerization initiator and the feed time of the monomer mixture were adjusted in proportion to the amount of the monomer.

Using these polymer emulsions, hollow polymer particles were prepared in the same manner as in Example 1. Table 3 shows the results.

Comparative Examples 5 and 6 In the same manner as in Example 1, core / shell particles were produced using the polymer emulsion (I) and the monomer composition shown in Table 4, and the resulting particles were physically expanded. Without subjecting the agent to absorption treatment, the temperature was raised to 130 ° C., and then the valve of the autoclave was opened, spouted into warm water maintained at 95 to 100 ° C., and allowed to cool to room temperature. Thus, the particles shown in Table 4 were obtained, but none of them had a clear hollow hole.

Example 18 A single separable flask equipped with a stirrer, a thermometer and a reflux tube was charged with sodium dodecylbenzenesulfonate.
0.2 parts by weight and Newcol 506 (manufactured by Nippon Emulsifier Co., Ltd.)
100 parts by weight of deionized water in which 2 parts by weight were dissolved, and 1.0 part by weight of a styrene / acrylic acid copolymer latex as seed particles of 400 ° C. were charged as a solid content, and the mixture was purged with nitrogen and heated to 80 ° C. A mixture of 80 parts by weight of styrene, 15 parts by weight of butyl acrylate, 2 parts by weight of methacrylic acid and 3.0 parts by weight of dodecyl mercaptan was added to the flask in 4.5 hours, 0.2 part by weight of sodium dodecylbenzenesulfonate, 0.2 part of Newcol 506 0.15 parts 20 parts by weight of deionized water in which 0.16 parts by weight of caustic soda and 0.8 parts by weight of sodium persulfate were dissolved were fed in 5.0 hours. Thereafter, the temperature was increased to 90 ° C. to complete the polymerization.
The particle size of the obtained polymer was 0.2 μm, and the solid content of the emulsion was 44% by weight.

Next, 65 parts by weight of deionized water obtained by dissolving 0.2 parts by weight of sodium dodecylbenzenesulfonate and 0.2 parts by weight of Newcol 506 in one separable flask equipped with a stirrer, a thermometer, and a reflux tube were obtained. 12.5 parts by weight of the prepared emulsion as a solid content, after nitrogen replacement,
Heated to 85 ° C. Into this flask, a mixed solution consisting of 53.4 parts by weight of styrene, 21.9 parts by weight of methyl methacrylate, 6.1 parts by weight of acrylonitrile, 3.5 parts by weight of methacrylic acid and 2.6 parts by weight of ethylene glycol dimethacrylate was added in an amount of 4.5 parts.
Added over time. However, ethylene glycol dimethacrylate was used for the polymerization reaction by adding it to the monomer mixture 2 hours after the start of the polymerization. In parallel with the addition of these monomers, 20 parts by weight of deionized water in which 0.2 parts by weight of sodium dodecylbenzenesulfonate, 0.15 parts by weight of Newcol 506, 0.16 parts by weight of sodium hydroxide and 0.8 parts by weight of sodium persulfate are dissolved. In 5.0 hours,
Thereafter, the temperature was increased to 90 ° C. to complete the polymerization. The particle size of the obtained polymer was 0.35 μm, and the solid content was 46% by weight.

Next, 46.7 parts by weight of the above emulsion (solid content 42% by weight)
%), And treated with an ultrasonic dispersing machine (Model 450, manufactured by Branson) for 30 seconds. The mixture was placed in a stainless steel autoclave equipped with a stirrer and stirred at 110 ° C. for 2 hours. During this time, the internal pressure of the autoclave was adjusted to 4 kg / cm ² with nitrogen gas. Next, the contents are purged with nitrogen from the jet nozzle,
It was squirted into a container maintained at atmospheric pressure. The particle size of the obtained emulsion was 0.40 μm. The volume increase rate (ΔV) by this operation is 60%. Observation of the cross section of the particle with a scanning electron microscope photograph showed that the particle size was consistent with the above particle size, and that a hollow hole of approximately 0.30 μm was formed.

Example 19 In a single separable flask equipped with a stirrer, a thermometer, a reflux tube, and an inlet tube, 0.2 part by weight of sodium dodecylbenzenesulfonate and 0.2 part by weight of Newcol 506 (manufactured by Nippon Emulsifier Co., Ltd.) were dissolved. 100 parts by weight of the deionized water thus obtained and 400 parts by weight of a styrene / allylic acid copolymer latex of 400 ° C. as seed particles were added in a charged solid content of 1.0 part by weight, purged with nitrogen, and heated to 80 ° C. In this flask, a mixed solution consisting of 80.0 parts by weight of styrene, 15.0 parts by weight of butyl acrylate, 2.0 parts by weight of methacrylic acid and 3.0 parts by weight of dodecyl mercaptan was added for 4.5 hours, 0.2 parts by weight of sodium dodecylbenzenesulfonate, Newcol 506 0.1
5 parts by weight, 0.16 parts by weight of sodium hydroxide and 20 parts by weight of deionized water in which 0.8 parts by weight of sodium persulfate were dissolved were fed in 5.0 hours. Thereafter, the temperature was increased to 90 ° C. to complete the polymerization. The particle size of the obtained polymer was 0.20 μm, and the solid content of the emulsion was 46% by weight.

Next, 105 parts by weight of deionized water obtained by dissolving 0.2 parts by weight of sodium dodecylbenzenesulfonate and 0.2 parts by weight of Newcol 506 in one autoclave equipped with a stirrer, a thermometer, a reflux tube, and an inlet tube, and The obtained emulsion was charged in an amount of 12.5 parts by weight based on the charged solid content, the atmosphere was replaced with nitrogen, and then heated to 85 ° C. To this autoclave, a mixed solution composed of 53.4 parts by weight of styrene, 21.9 parts by weight of methyl methacrylate, 6.1 parts by weight of acrylonitrile, 3.5 parts by weight of methacrylic acid, 10.0 parts by weight of cyclohexane and 2.6 parts by weight of ethylene glycol dimethacrylate was added over 4.5 hours. However, ethylene glycol dimethacrylate was used for the polymerization reaction by adding it to the monomer mixture 2 hours after the start of the polymerization. In parallel with the addition of these monomers, 20 parts by weight of deionized water in which 0.2 parts by weight of sodium dodecylbenzenesulfonate, 0.15 parts by weight of Newcol 506, 0.16 parts by weight of sodium hydroxide and 0.8 parts by weight of sodium persulfate are dissolved. Was fed in 5.0 hours. Thereafter, the temperature was increased to 90 ° C. to complete the polymerization. The particle size of the obtained polymer was 0.35 μm, and the conversion was 100%.

After the polymerization, the autoclave is purged with nitrogen to an internal pressure of 4 kg / cm.
^After adjusting to ² and stirring at 110 ° C. for 2 hours, the mixture was discharged into a low pressure region under a nitrogen atmosphere at 25 ° C. The particle size of the polymer emulsion thus obtained was 0.39 μm. The polymer emulsion was internally added to the resin, and the cut surface was observed. As a result, it was confirmed that the polymer particles had 0.25 μm hollow holes.

Example 20 100 parts by weight of deionized water obtained by dissolving 0.2 parts by weight of sodium dodecyl bezensulfonate and 0.2 parts by weight of Newcol 506 in one autoclave equipped with a stirrer, a thermometer, a reflux pipe, and an inlet pipe, and seed particles Styrene / allylic acid copolymer latex of 400% as charged solid content of 1.0
After putting in parts by weight and purging with nitrogen, the mixture was heated to 80 ° C. In this flask, a mixture of styrene 80.0 parts by weight, butyl acrylate 15.0 parts by weight, methacrylic acid 2.0 parts by weight, cyclohexane 10 parts by weight and dodecyl mercaptan 3.0 parts by weight for 4.5 hours, and sodium dodecylbenzenesulfonate 0.2 parts by weight Parts, Newcol 506 0.2 parts by weight, caustic soda 0.16 parts by weight and sodium persulfate 0.8
20 parts by weight of deionized water in which parts by weight were dissolved were fed in 5.0 hours. Thereafter, the temperature was increased to 90 ° C. to complete the polymerization. The particle size of the obtained polymer is 0.21 μm, and the conversion is 99%.
Met.

Next, 105 parts by weight of deionized water obtained by dissolving 0.2 parts by weight of sodium dodecylbenzenesulfonate and 0.2 parts by weight of Newcol 506 in one autoclave equipped with a stirrer, a thermometer, a reflux tube, and an inlet tube were obtained. 12.5 parts by weight of the obtained emulsion was added as a charged solid content, the atmosphere was replaced with nitrogen, and then heated to 85 ° C. In this autoclave, styrene
A mixture of 53.4 parts by weight, 21.9 parts by weight of methyl methacrylate, 6.1 parts by weight of acrylonitrile, 3.5 parts by weight of methacrylic acid, 8.7 parts by weight of cyclohexane and 2.6 parts by weight of ethylene glycol dimethacrylate was added over 4.5 hours. However, ethylene glycol dimethacrylate is
Two hours after the start of the polymerization, the mixture was added to the monomer mixture to conduct a polymerization reaction. In parallel with the addition of these monomers, 20 parts by weight of deionized water in which 0.2 parts by weight of sodium dodecylbenzenesulfonate, 0.2 parts by weight of Newcol 506, 0.16 parts by weight of sodium hydroxide and 0.8 parts by weight of sodium persulfate are dissolved. Was fed in 5.0 hours. Thereafter, the temperature was increased to 90 ° C. to complete the polymerization. The particle size of the obtained polymer was 0.34 μm, and the conversion was 100%.

After the polymerization, the autoclave is purged with nitrogen to an internal pressure of 4 kg / cm ^2.
After stirring at 110 ° C. for 2 hours, the mixture was discharged into a low pressure region under a nitrogen atmosphere. The particle size of the polymer emulsion thus obtained was 0.38 μm. The polymer emulsion was internally added to the resin, and the cut surface was observed. As a result, it was confirmed that the polymer particles had 0.25 μm hollow holes.

Examples 21 to 30 Hollow polymer particles were produced in the same manner as in Example 19. Table 5 summarizes the results.

Comparative Example 7 Toluene (boiling point: 111 ° C.) instead of cyclohexane
Polymer particles were produced in the same manner as in the case of the weight part 19 except for using, and subjected to a foaming test. However, almost no hollow was observed in the obtained polymer particles.

Claims (2)

(57) [Claims] 1. A core part 1 comprising a substantially non-crosslinked polymer.
Core / shell type polymer particles composed of 99 to 25% by weight of a shell portion composed of a crosslinked polymer containing about 75% by weight and 0.3% by weight or more and less than 30% by weight of a crosslinkable monomer unit; A weight average particle diameter of a physical foaming agent having a boiling point of 95 ° C. or less impregnated into a core portion and a shell portion.
An expandable polymer emulsion composition comprising an expandable polymer particle having a particle size of from 0.05 to 1.0 μm. 2. The foamable polymer emulsion composition according to claim 1, wherein the weight ratio of the core / shell type polymer particles to the physical blowing agent is from 100: 1 to 1: 3.