JPH0374441A - Amphoteric hollow polymer particle, production thereof and paper coating composition using the same particle - Google Patents

Abstract

PURPOSE:To obtain the subject lightweight hollow polymer particles which are polymer particles having hollow pores and a specific outside diameter at a specific pH providing a precipitation point with good opacity and gloss and useful as a pigment component for coating paper or various coatings. CONSTITUTION:The objective hollow polymer particles, obtained by swelling 100 pts.wt. polymer particles with 0.1-5 pts.wt. cationic emulsifying agent (e.g. laurylamine) according to two-stage emulsion polymerization, forming core/shell type polymer particles having a core, subjecting the resultant particles to expansion treatment and, as necessary, removing treatment of an inert liquid and having 0.05-100mum outside diameter and hollow pores with a diameter of 1-99% based on the aforementioned outside diameter at pH3-9 providing a precipitation point. The above-mentioned hollow polymer particles in an amount of 0.1-50wt.% are contained in an inorganic filler to afford a paper coating composition.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to novel amphoteric hollow polymer particles, a method for producing them, and a paper coating composition using the particles.

More specifically, the present invention is useful as, for example, a pigment component for paper coating or a pigment component for various paints, is lightweight, scatters visible light well, has good opacity, water absorption,
Amphoteric hollow polymer particles having ink transfer properties, a method for efficiently producing the particles, and a paper coating composition that provides coated paper with excellent optical properties such as whiteness, printing gloss, and rigidity. It is something.

Conventional technology Conventionally, organic pigments have been widely used as pigment components for paper coatings and various paints because they are lighter than inorganic pigments and have thermoplastic characteristics. ing. In such applications, the interior of the retarded particles is hollowed out for the purpose of further improving lightness, opacity, and the like. This hollowing occurs for particles whose diameter is on the order of the wavelength of visible light.
It is known that if the inside is made hollow, the scattering effect of visible light can be further enhanced and the opacity can be improved.

Conventionally, methods for producing such hollow polymer particles include:
For example, a method of swelling core/shell type particles having an alkali-swellable core with an alkali, water-oil-one-water (W10/
A method of preparing a W) type monomer emulsion and performing polymerization is used.

On the other hand, as printing speeds have increased in recent years, it has been desired to improve water absorption and ink transfer properties, but when amphoteric polymer particles are used as a binder for paper coating, water absorption is improved and ink transfer properties are improved. It is known that the transferability of the coating is improved and a coating layer with high water resistance can be obtained. Examples of methods for producing such amphoteric polymer particles include (1) a method of copolymerizing a cationic monomer and an anionic heptamer, and (2) a method of polymerizing an ionic monomer to give an ion of the opposite sign to that of the monomer. A method of copolymerization using an initiator, and (3) a method of post-treating polymer particles to change the charge state on the surface of the particles are known.

However, although conventional hollow polymer particles have excellent opacity and light weight, when used as a binder for paper coating, etc., they are inferior to amphoteric polymer particles in terms of water absorption and ink transfer properties. It has its drawbacks. In addition, amphoteric polymer particles are used as binders for paper coating, etc., but at present, amphoteric hollow polymer particles with hollow pores and excellent lightness, opacity, and gloss have not yet been found. It is.

Problems to be Solved by the Invention Under these circumstances, the present invention aims to provide a paper coating material that is lightweight, scatters visible light well, and has good opacity, water absorption, and ink transferability. Amphoteric hollow polymer particles useful as a pigment component or a pigment component for various paints, a method for efficiently producing the same, and optical properties such as whiteness, printing gloss, etc. containing the amphoteric hollow polymer particles. physical properties,
The purpose of this invention is to provide a paper coating composition that provides coated paper with excellent rigidity.

Means for Solving the Problems As a result of extensive research into amphoteric hollow polymer particles that are lightweight, scatter visible light well, and have good opacity, water absorption, and ink transferability, the inventors have discovered two Obtained by step polymerization to form core/shell type polymer particles having a core swollen with an inert liquid containing an amphoteric emulsifier, followed by foaming treatment and, if necessary, removal treatment of the inert liquid. It was discovered that the above object could be achieved by hollow polymer particles having amphoteric properties and having an outer diameter and a hollow pore diameter within a specific range, and based on this knowledge, the present invention was completed.

That is, the present invention provides polymer particles having an outer diameter of 0.05 to 100 μm and having hollow pores with a diameter of 1 to 99% of the outer diameter, and a pH that gives a precipitation point of 3 to 99%. 9 and an inorganic pigment, and 0.1 to 50% by weight of the amphoteric hollow polymer particles based on the inorganic pigment. It is something that provides something.

According to the invention, the amphoteric hollow polymer particles are subjected to two-stage emulsion polymerization to form core/shell type polymer particles with a core swollen by an inert liquid containing an amphoteric emulsifier, followed by foaming treatment and It can be manufactured by performing an inert liquid removal process if necessary.

The present invention will be explained in detail below.

The amphoteric hollow polymer particles of the present invention are substantially spherical, and
Its outer diameter is O,OS~100μ, preferably 0.07
It is preferable to have a richness of 0.1 to 1 μm, more preferably 10 μm. If the outer diameter deviates from the above range, the object of the present invention cannot be fully achieved.

The hollow polymer particles of the present invention are polymer particles containing one or more, preferably one, hollow pore inside, and this hollow pore is also substantially spherical, with a diameter of 1 to 1 of the outer diameter. 99%
, preferably 10-80%, more preferably 20-70%
% range. If the diameter of the hollow pores is smaller than this range, the light weight and opacity may be insufficient, and if the diameter is larger, the physical strength of the particles themselves tends to decrease.

The polymer constituting the hollow polymer particles is usually obtained by polymerizing a dical polymerizable monomer, and examples of the monomer include styrene, 0-methylstyrene, m-
Methylstyrene, p-methylstyrene, ethylstyrene, ar-vinylxylene, ar-') lorostyrene, a
Styrene derivatives such as r-bromostyrene, vinylbenzyl chloride, p-tert-butylstyrene, methyl-, propyl-1n-butyl-, imbutyl-1-tert-butyl-
1n-amyl-, in-amylhexyl-, octyl-,
Nonyl-, decyl-dodecyl-, octadecyl-cyclohexyl-, phenyl-, benzyl-acrylates or methacrylates, vinyl acetate, vinyl butyrate, vinyl stearate, vinyl laurate, vinyl myristate, vinyl propionate , vinyl esters such as vinyl persate, methyl, ethyl,
Examples include vinyl ethers having alkyl groups such as propyl, butyl, amyl, and hexyl.

Furthermore, other unsaturated monomers include vinyl cyanides such as acrylonitrile and methacrylaterile, vinyl chloride, vinyl bromide, vinyl heptadide, vinylidene fluoride, vinylidene chloride, etc. (7)/%C7'y' dienes such as butadiene, chloroprene, isoprene, unsaturated dibasic acid alkyl esters such as mono- or dialkyl esters such as maleic acid, heptamalic acid, itaconic acid, olefins such as ethylene, glycidyl (meth) Acrylates and methylglycidyl (meth)
Glycidyl compounds such as acrylates, amides such as acrylamide and methacrylamide, their N-methylol compounds and alkoxy compounds, silicon-containing σ such as vinyltrichlorosilane and vinyltriethoxysilane
, β-ethylenically unsaturated monomers, hydroxyl group-containing σ, β-unsaturated monomers such as β-hydroxyacrylate and β-hydroxymethacrylate, acrylic acid, methacrylic acid,
a, β-ethylenically unsaturated carboxylic acids such as itaconic acid, citraconic acid, maleic acid, hexamaric acid, vinylbenzoic acid, cinnamic acid, unsaturated acids such as vinylsulfonic acid and styrenesulfonic acid, vinylpyridine, dimethyl Examples include basic monomers such as aminoethyl acrylate, dimethylaminoethyl acrylate, diethylaminoethyl acrylate, and diethylaminoethyl methacrylate.

These monomers may be used alone or in combination of two or more, and a crosslinkable monomer that provides a crosslinked polymer may be used in combination as appropriate. Examples of the crosslinkable monomer include ethylene glycol methacrylate, 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, l,5-bentanediol diacrylate, neopentyl glycol diacrylate, 1,6-hexanediol diacrylate, diethylene glycol diacrylate, triethylene glycol diacrylate, tetraethylene glycol diacrylate Examples include acrylate, polyethylene glycol diacrylate, polypropylene glycol diacrylate, pentaerythritol acrylate, trimethylolpropane triacrylate, tetramethylolmethanetetraacrylate, and allyl methacrylate. 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 are of course used as crosslinking monomers. Can be used. One type of these crosslinkable monomers may be used, or two or more types may be used in combination.

It is necessary that the hollow polymer particles of the present invention be amphoteric. In the present invention, this amphoteric means p which provides the precipitation point.
It means that a has a value of 3 to 9.

This precipitation can be easily measured by experiment. That is, the hollow polymer particles 35119 of the present invention were dropped into buffer solution 20aQ adjusted to each pu, stirred, and then allowed to stand for 24 hours. The light transmittance of the supernatant at 470 nm was measured, and the value was 80. It is the highest value of I)H showing % or more.

The amphoteric hollow polymer particles of the present invention may be dispersed in a dispersion medium such as water, or may be processed into powder.

To produce such amphoteric hollow polymer particles, according to the invention, a two-stage polymerization is first performed to form core/shell type polymer particles having a core swollen by an inert liquid containing an amphoteric emulsifier. let

The amphoteric emulsifier is not particularly limited, and generally available amphoteric emulsifiers can be used.

This amphoteric emulsifier is an emulsifier that has parent groups of a cation part and an anion part in the same molecule, and the cation part contains amine salts and quaternary ammonium salts, and the anion part contains carboxylic acid salts and sulfuric acid ester salts. , sulfonate, and phosphate ester salts can be used. Examples of such substances include lauryl betaine, stearyl betaine, cocoamidopropyl betaine,
Salts of alkyl betaines such as 2-undecyl-hydroxyethylimidazolinium betaine, carboxymethyl-N-hydroxyethylimidazolinium betaine, lauryl-β-alanine, lauryl (aminoethyl)glycine, stearyl-β-alanine, octyl ( Mention may be made of amino acid type salts such as aminoethyl)glycine, dioctyl(aminoethyl)glycine, etc. These amphoteric emulsifiers may be used alone or in combination of two or more, and the amount used is not particularly limited, but is usually 0.0 parts by weight per 100 parts by weight of polymer particles.
It is selected in the range of 1-10 parts by weight, preferably 0.1-5 parts by weight.

Further, the inert liquid is not particularly limited as long as it has an affinity for the polymer forming the core of the core/shell type polymer particles. For example, if the core polymer is water-soluble, water can be used as the inert liquid, and if it has an affinity for common organic solvents, that organic solvent can be used. Examples of the organic solvent include aliphatic hydrocarbons such as ethane, ethylene, propylene, propane, butane, butadiene, pentane, hexane, heptane, cyclohexane, imbutylene, and neopentane, methyl chloride, methylene chloride, ethyl chloride, chloroform, and Chlorinated hydrocarbons such as carbon chloride, trichloroethane, fluorinated chlorinated hydrocarbons such as trichlorofluoromethane, dichlorodifluoromethane, dichlorofluoromethane, chlorodifluoromethane, trichlorotrifluoroethane, dichlorotetrafluoroethane, acetone, diethyl ketone, Ketones such as dibutyl ketone, alcohols such as methanol, ethanol, furopanol, butanol, ethers such as dimethyl ether, diethyl ether, dibutyl ether, tetrahydrofuran, aromatic hydrocarbons such as benzene, toluene, xylene, methyl methacrylate, styrene, etc. Examples include volatile monomers such as These inert liquids may be used alone or in combination of two or more, and the amount used is usually 1 to 1000% by weight, preferably 1 to 200% by weight based on the monomer particles. Selected within a range of %.

Next, a method for forming core/shell type polymer particles having a core swollen with an inert liquid containing the amphoteric emulsifier will be described. There are two main methods for this method: one is to form core/shell polymer particles in the presence of an inert liquid, and the other is to form core/shell polymer particles in the presence of an inert liquid. This is a method in which after producing combined particles, an inert liquid is absorbed into the particles.

There are no particular restrictions on the method for producing core/shell type polymer particles, and conventionally known methods can be employed. In the first method, for example, core particles are first formed by emulsion polymerization, and then, in the presence of the core particles, a polymer constituting the shell (hereinafter referred to as shell polymer)
can be obtained by emulsion polymerization in the presence of an inert liquid. There are two ways to use the inert liquid in this story: first, the core particles are swollen with the liquid, and then the shell polymer is polymerized; and the other is to mix the monomers forming the shell polymer with the inert liquid. There is a method of subjecting it to a polymerization system, and either method may be used. In addition, as a method for manufacturing these core/shell polymer particles, a method called so-called phase-in purging can also be adopted. In this case, the polymer constituting the core (hereinafter referred to as core Desired core/shell type polymer particles can be obtained by emulsion polymerization of monomers forming the polymer in the presence of an inert liquid. When producing hollow polymer particles by this method, it is necessary to design so that the inert liquid mainly exists in the core part, and the affinity of the polymer
It is important to make a decision taking into consideration molecular weight, etc.

In the second method, core/shell polymer particles are first formed by two-stage emulsion polymerization as described above, and then an inert liquid is absorbed into the particles. When such methods are used in combination, it is necessary that the core polymer has an affinity for the inert liquid, and that the shell polymer also has an affinity for penetrating and passing the inert liquid.

As the emulsion polymerization method, a conventionally known method is used, such as a method in which a desired monomer is polymerized using a polymerization initiator in the presence of an emulsifier and a chain transfer agent or seed particles used as necessary. be able to. In the present invention, it is necessary to use the above-mentioned amphoteric emulsifier as the amphoteric emulsifier, but if desired, an anionic or nonionic emulsifier may be used in combination with the amphoteric emulsifier as long as the purpose of the present invention is not impaired. I can do it.

As the anionic emulsifier, for example, alkyl benzene sulfonic acid alkali metal salts, alkyl sulfate alkali metal salts, polyoxyethylene alkylphenol sulfate alkali metal salts, alkyl sifphenyl ether disulfonic acid alkali metal salts, dialkyl sulfosuccinic acid alkali metal salts, etc. may be used. I can do it. on the other hand,
As the nonionic emulsifier, for example, polyoxyethylene alkylphenol ether, polyoxyethylene alkyl ether, polyoxyethylene higher fatty acid ester, ethylene oxide-propylene oxide block copolymer, etc. can be used.

Furthermore, an acrylic water-soluble oligomer may be used in combination with the anionic emulsifier. Furthermore, polyvinyl alcohol, hydroxyethyl cellulose, etc. can be used as required. As the amount of these emulsifiers and water-soluble polymer compounds increases, the water resistance of the resulting polymer may decrease. mechanical stability,
It is preferable to use the minimum amount necessary to maintain chemical stability. The amount used is usually selected within the range of 0.1 to 7 parts by weight per 100 parts by weight of the monomer.

The chain transfer agent is not particularly limited and can be appropriately selected from those commonly used for controlling the molecular weight in ordinary polymerization reactions. Examples of such chain transfer agents include mercaptans having an alkyl group having 1 to 30 carbon atoms, such as propyl mercaptan, butyl mercaptan, and dodecyl mercaptan, and mercaptans having 1 to 30 carbon atoms, such as octyl thioglyflate, thioglycolic acid, and diphenyl sulfide.
30 organic sulfur compounds, carbon tetrachloride, carbon tetrabromide,
Included are halogenated hydrocarbons having 1 to 20 carbon atoms, such as bromotrichloromethane. These chain transfer agents may be used alone or in combination of two or more.

As a polymerization initiator, at a temperature of about o-1so°C,
Compounds that generate radicals are used.

As this polymerization initiator, mainly water-soluble ones are used, but oil-soluble ones may also be used.

Typical polymerization initiators include water-soluble persulfates such as ammonium persulfate, sodium persulfate, and potassium persulfate, inorganic peroxides such as hydrogen peroxide, benzoyl peroxide, cumene hydroperoxide, lauroyl peroxide, Examples include organic peroxides such as tert-butyl peroxide and -tert-butyl peroxy-2-ethylhexanoate, and azo compounds such as azobisin butyronitrile. Alternatively, the above peroxide and reducing agent are combined to generate radicals in the presence of a trace amount of metal ions.
So-called redox-based initiators are also used. Examples of this redox system include hydrogen peroxide-ferrous chloride system and cumene hydroperoxide-sodium ascorbate system. Furthermore, initiators having amine groups such as azobisisobutylamine can also be used. The amount of these polymerization initiators to be used is usually selected within the range of 0.1 to 2.5 parts by weight based on 100 parts by weight of the total amount of monomers. Further, one type of the above peroxide may be used,
Two or more types may be used in combination.

The polymerization reaction is usually carried out at 0-130°C, preferably 30-10
It is carried out at a temperature in the range of 0°C. The polymerization time is not particularly limited, and is usually 1 to 24 hours, preferably 1 to 6 hours.

In the present invention, conventionally known methods can be used to control the outer diameter of the hollow polymer particles. For example, the outer diameter can be arbitrarily changed by changing the amount of emulsifier, the amount of seed particles, etc. can. In addition, several methods are known for designing the size of the inner diameter, such as a method of appropriately changing the core/shell ratio,
A method of changing the amount of inert liquid relative to the polymer particles, a method of appropriately changing the physical foaming conditions, etc. can be adopted. Moreover, when producing polymer particles having a particle size of 10° C. or more, a so-called suspension polymerization method can also be employed.

Next, the thus obtained core/shell type polymer particles having a core swollen with an inert liquid containing an amphoteric emulsifier are subjected to a foaming treatment and, if necessary, an inert liquid removal treatment. Ru. When performing foaming treatment, an operation is performed in which an emulsion containing particles encapsulating an inert liquid is set at an appropriate temperature and pressure, and then transferred to a low pressure region. The temperature and pressure at this time have a great effect on the degree of foaming, and this temperature needs to be higher than the boiling point of the inert liquid. At temperatures below the boiling point, hardly any foamed particles can be obtained.

In addition, at this temperature, the particles, especially the shell polymer, must have sufficient deformation fluidity, but it is also necessary that the gas permeability is low enough to cause the particles to expand under the foaming pressure. It is important that the material has tensile strength to resist. Therefore, the emulsion temperature is not necessarily better as it is higher, but is preferably in the range from the boiling point of the inert liquid to a temperature 50° C. higher than this boiling point.

There are no particular restrictions on the pressure of the emulsion, but since it is heated above the boiling point of the inert liquid, the natural pressure is usually higher than atmospheric pressure, and this natural pressure may be used, but it may be kept at a pressure higher than this. It is preferable to do so because it is easier to obtain particles with high foamability.

Furthermore, since the pressure is closely related to the speed of transition to the low pressure side, this point must also be taken into consideration.

The polymer emulsion heated and pressurized in this manner is transferred to a low pressure region to expand the polymer particles. The atmosphere in this low pressure region may be gas or liquid.

If the gas is an inert gas such as nitrogen, if the liquid is water it is preferred. The temperature in the low pressure region is appropriately selected depending on the composition of the polymer particles, the type and amount of inert liquid contained in the particles, and is usually below the temperature of the polymer emulsion. Once most of the inert liquid 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. The transfer of the polymer emulsion from the high pressure area to the low pressure area may be carried out by directly reducing the pressure of the emulsion system, but it is usually done using a single hole, multiple holes, or slit type, or by controlling the flow rate and pressure change during the transition. A method using a hollow-shaped moving opening is used. In the present invention, it is preferable to carry out such physical foaming because larger hollow pores can be formed.

Next, in the present invention, an operation for removing the inert liquid is performed as necessary. There are no particular restrictions on this method, and any conventional method can be used as is. Specifically, a method of heating and distilling under reduced pressure, a spray drying method, a freeze drying method, etc. may be used if necessary. If the hollow polymer particles of the present invention are desired in the form of an aqueous emulsion, a heating distillation method is employed, in which case the inert liquid preferably has a boiling point lower than that of water.

Moreover, when desired in the form of powder, spray drying, freeze drying, etc. are employed.

The object of the present invention is to provide the above-mentioned amphoteric hollow polymer particles and a method for producing the same, as well as a paper coating comprising an inorganic pigment and 0.1 to 50% by weight of the amphoteric hollow polymer particles based on the inorganic pigment. The purpose of the present invention is to provide an industrial composition.

In addition to the inorganic pigment and the amphoteric hollow polymer, the paper coating composition of the present invention usually contains a dispersion medium, a binder, various additives, etc. Examples of the inorganic pigment include clay, calcium carbonate, etc. , aluminum hydroxide, talc, titanium oxide, lithopone, satin white, zinc oxide, etc., and each may be used alone or in combination of two or more.

Examples of the binder include a polymer emulsion, a water-soluble binder, etc. The polymer emulsion is an emulsion using water as a dispersion medium, and examples of such binders include styrene-butadiene, styrene- Examples include acrylic, acrylic, ethylene-vinyl acetate, vinyl acetate-acrylic, vinyl acetate, vinylidene chloride, and natural rubber latex. These polymer emulsions may contain functional groups such as carboxyl groups, hydroxyl groups, N-methylol groups, amide groups, glycidyl groups, and sulfonic acid groups. This polymer emulsion is not limited to one type of polymer, but may be a mixture of two or more types, or may have alkaline thickening properties,
Further, the particle size of the polymer particles is usually 0.05 to 1 μm, and the solid content concentration is 40 to 65% by weight. On the other hand, examples of water-soluble binders include starch, modified starch, polyvinyl alcohol, carboxymethyl cellulose, casein, and soybean protein. These binders may be used alone or in combination of two or more, and the amount is usually 5 to 40 parts per 100 parts by weight of the pigment.
Parts by weight are selected, preferably in the range of 5 to 30 parts by weight.

In the paper coating composition of the present invention, the hollow polymer particles are contained in an amount of 0.1 to 50% by weight, preferably 0.5 to 50% by weight based on the pigment.
It is necessary to mix it in a proportion of 20% by weight. If the content of the hollow polymer particles is less than 0.1% by weight, the effect of improving opacity etc. will not be sufficiently exhibited;
If the amount exceeds 1, no improvement in opacity is observed considering the amount, and other physical properties such as fluidity of the composition tend to deteriorate.

The paper coating composition of the present invention may contain various commonly used additives, such as dispersants, lubricants, antifoaming agents,
Preservatives, waterproofing agents, anti-aging agents, etc. can be included. Further, the solid content concentration of this paper coating composition is usually selected in the range of 30 to 75% by weight, preferably 40 to 75% by weight. As the pH adjuster, potassium hydroxide, sodium hydroxide, ammonia, etc. are usually used.

The paper coating composition of the present invention is prepared by appropriately mixing inorganic pigments such as clay and calcium carbonate, binders, dispersants, hollow polymer particles, and other additives added as necessary. It will be done.

At this time, there are no particular restrictions on the method of adding the hollow polymer particles, and they may be added as appropriate during the preparation of the paper coating composition, or they may be mixed in advance with a binder such as a polymer emulsion. . The dispersion medium for paper coating fluids usually contains
water is used.

The paper coating composition of the present invention is usually prepared as a paper coating liquid and used for coating paperboard, general wood-free paper, medium-quality paper, gravure paper, and the like. When applying this paper coating liquid to the above-mentioned paper, use a size plate 1/scater, a roll coater, etc.
Any known method using an air knife coater, blade coater, etc. may be employed. The amount of coating varies depending on the purpose of use and is not particularly limited, but in terms of solid content,
Usually 0. 1 to 309/II''.

Effects of the Invention The amphoteric hollow polymer particles of the present invention are light in weight, scatter visible light well, and have good opacity, water absorption, and ink transferability, and are useful, for example, as pigment components for paper coating and various paints. It is useful as a pigment component for industrial applications.

In addition, the paper coating composition of the present invention containing the amphoteric hollow polymer particles has excellent optical properties such as whiteness and printing gloss, and rigidity, as well as wet strength, which has been difficult to achieve at the same time. It is also possible to provide coated paper with extremely good printability such as water absorption, ink transferability, etc.

Examples Next, the present invention will be explained in more detail with reference to examples.
The present invention is not limited in any way by these examples.

In addition, each physical property and other physical properties in coated paper production were determined as follows.

(1) Color viscosity: 60 by Brookf 1eld type (B type) viscometer
rp+.

Measured at Also, using a Vercules viscometer, 44
Measured at 00 rpm-.

(2) Blank paper gloss It was measured at 75@-75@ using a gloss meter.

(3) After printing on an ink gloss coated paper sample using a printing tester using a 0.3-ink ink (manufactured by Toyo Ink Co., Ltd., New Bright G Indigo), the humidity was adjusted day and night and then a gloss meter was used. Measured at 60'-60'.

(4) Printability Dry strength, wet strength, ink receptivity, water absorption, and ink set were measured using an ink having an appropriate tack using a printing tester, and evaluated in the following four stages.

@: *Always good ○: Good Δ: Slightly poor ×: Very poor (5) Blister resistance Double-sided coated and calendar-finished coated paper was printed with yellow ink using Mei Seisakusho Co., Ltd. R1 printing machine. (0-3cc)
Make a solid print of the screen and use it as a sample. This sample was immersed in a heated oil bath, and the temperature at which blistering occurred was read and evaluated as follows.

O Ni blisters do not occur at all. 0 Ni blisters occur slightly. Δ Ni blisters occur considerably. x Ni blisters occur all over the surface.
It was expressed as

(7) Polymer emulsion particle diameter (μm) Polymer emulsion was treated with osmic acid, magnified 30,000 times with a scanning electron microscope, and the diameter of 500 particles was measured in the obtained micrograph. It was calculated by averaging these numbers.

(8) Stiffness (!I) Paper was made into a strip of 2C width, and its stiffness was measured using a Clark stiffness tester.

Example 1 Nucor 506 (Nippon Nyukazai Co., Ltd.) was added to a LA separable flask equipped with a stirrer, thermometer, and reflux tube.
100 parts by weight of deionized water in which 0.2 parts by weight (manufactured by Manufacturer, Inc.) was dissolved and 1.0 parts by weight of styrene/acrylic acid copolymer latex (weight ratio 96/4) with a particle size of 430 people as seed particles (calculated as solid content). 80 parts by weight of styrene, 15 parts by weight of butyl acrylate, and 3.0 parts of dodecyl mercaptan were added to the flask.
0.15 parts by weight of Nucol 5060 and 0.1 parts by weight of sodium hydroxide.
20 parts by weight of deionized water in which 6 parts by weight and 0.8 parts by weight of sodium persulfate were dissolved were fed over 5.0 hours. Thereafter, the temperature was raised to 90°C to complete the polymerization. The particle size of the obtained polymer was 0.2 μm, and the solid content concentration of the emulsion was 44% by weight.

Next, 65 parts by weight of deionized water in which 0.2 parts by weight of lauryl di(aminoethyl)glycine and 0.2 parts by weight of Nucor 506 were dissolved in 112 separable flasks equipped with a stirrer, thermometer, and reflux tube, and 12.5 parts by weight of the emulsion obtained above was added in terms of solid content, the air was purged with nitrogen, and the mixture was heated to 85°C.

A liquid mixture consisting of 53.4 parts by weight of styrene, 21.9 parts by weight of methyl methacrylate, 6.1 parts by weight of acrylonitrile and 2.6 parts by weight of ethylene glycol dimethacrylate was added to this flask over 4.5 hours. However, ethylene glycol dimethacrylate was subjected to the polymerization reaction by adding it to the monomer mixture 2 hours after the start of polymerization.

In parallel with the addition of these monomers, 5 parts by weight of deionized water in which 0.15 parts by weight of Nucol 506, 0.16 parts by weight of sodium hydroxide and 0.8 parts by weight of sodium persulfate were dissolved were added. .Feeded in 0 hours. after that,
The temperature was raised to 90°C to complete the polymerization. The particle size of the obtained polymer was 0.35 μm, and the solid content concentration was 46% by weight.

Next, 46.7 parts by weight of the emulsion (solid content concentration 4
2% by weight) was added to 10.0 parts by weight of cyclohexane, and the mixture was dispersed with ultrasonic dispersion wA (Model 450 manufactured by Branson) at 30% by weight.
Processed for seconds. This 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 increased to 4.
kg/cm". Next, the contents were jetted from a jet nozzle into a container that was purged with nitrogen and maintained at atmospheric pressure.

When the particle size of the obtained emulsion was measured by a light scattering method, it was found to be 0.40 μm. The volume increase rate (ΔV) due to this operation was 49%.

When the cross-section of the particles was observed using a scanning electron micrograph, results consistent with the particle size described above were obtained, and the diameter was approximately 0.
．． It was observed that hollow pores with a shoulder size of 28μ were formed. The pH that gives the precipitation point of this substance was measured and was found to be 5.
It was 1.

Example 2 II2 separable flask equipped with a stirrer, thermometer, reflux tube, and inlet tube, 100 parts by weight of deionized water in which 0.3 parts by weight of Newcoal 506 (Nippon Nyukazai Co., Ltd. II) was dissolved. Then, 0.24 parts by weight of styrene/acrylic acid copolymer latex having a grain size of 1400 A was added as seed particles, and the mixture was purged with nitrogen and then heated to 80°C. A mixed solution consisting of 80.0 parts by weight of styrene, 15.0 parts by weight of butyl acrylate, and 3.0 parts by weight of dodecyl mercaptan was added to this flask over 4.5 hours, and 0.15 parts by weight of Nucol 506, hydroxylated 20 parts by weight of deionized water in which 0.16 parts by weight of sodium and 0.8 parts by weight of sodium persulfate were dissolved was fed over 5.0 hours. Thereafter, the temperature was raised to 90°C to complete the polymerization. The particle size of the obtained polymer was 0.30 μm, and the solid content concentration of the emulsion was 46% by weight.

Next, a l
105 parts by weight of deionized water in which 0.2 parts by weight of stearyl betaine and 0.2 parts by weight of Nucor 506 were dissolved and 12.5 parts by weight of the emulsion obtained above were placed in a Q autoclave, and the atmosphere was replaced with nitrogen. After that, 8
Heated to 5°C. In this autoclave, styrene 56
．． 9 parts by weight, 21.9 parts by weight of methyl methacrylate, 6.1 parts by weight of acrylonitrile, 20.0 parts by weight of cyclohexane
Parts by weight and ethylene glycol dimethacrylate 2.6
The weight mixture was added over a period of 4.5 hours. However, ethylene glycol dimethacrylate was subjected to the polymerization reaction by adding it to the monomer mixture 2 hours after the start of polymerization. In parallel during the addition of these monomers, 0.15 parts by weight of Nucor 506, o, i of sodium hydroxide
20 parts by weight of deionized water in which 0.8 parts by weight of sodium persulfate and 0.8 parts by weight of sodium persulfate were dissolved were fed for 5.0 hours. Thereafter, the temperature was raised to 90°C to complete the polymerization. The particle size of the obtained polymer was 0.60μ, and the polymerization rate was 100%. The polymer emulsion thus obtained was freeze-dried to form a powder. When this powder was embedded in a resin and its cut surface was observed, it was confirmed that the polymer particles had hollow pores with a shoulder of 0.35 μm. The pH that gives the precipitation point of this product was measured and found to be 5.8.

Example 3 A polymer emulsion (with a number average particle diameter of 0.5 parts by weight) prepared by emulsion polymerization of a mixture of 60 parts by weight of styrene, 28 parts by weight of butadiene, 10 parts by weight of methyl methacrylate, 2 parts by weight of fumaric acid, and 5 parts by weight of carbon tetrachloride. 18 μm) and the hollow polymer particles prepared in Example 1, a composition (solid content concentration 61% by weight) with the color combination shown in Table 1 was prepared, and this was coated by adjusting the pH to 9 with an ammonia aqueous solution. Industrial II! I got something.

The viscosity of this coating composition was measured, and then coated on a commercially available high-quality paper using a blade-type continuous winding coating machine.
It was coated on both sides (one side).

Furthermore, using a super calender device, 50℃, 15he
Each side was passed twice under the condition of "/cm". The print quality of the coated paper thus produced was evaluated and the results are shown in Table 3.

Example 4 Styrene 50 was used instead of the polymer emulsion of Example 3.
parts by weight, 38 parts by weight of butadiene, 5 parts by weight of ethyl acrylate
Coated paper was prepared in the same manner as in Example 3, except that a polymer emulsion (number average particle diameter 0.15 μm) prepared using 5 parts by weight of acrylonitrile and 2 parts by weight of itaconic acid was used. . The evaluation results are shown in Table 3.

Example 5 The same procedure as Example 3 was used except that an alkali-thickened latex (Latex L-1295, manufactured by Asahi Kasei Corporation, pH 5,7) and hollow polymer particles of Example 2 were used, and the formulation shown in Table 2 was used. Coated paper was produced using a similar method. The evaluation results are shown in Table 3.

Comparative Example 1 Anionic non-hollow polymer obtained by conventional emulsion polymerization of 90 parts by weight of styrene, 6 parts by weight of methyl methacrylate, and 4 parts by weight of methacrylic acid instead of hollow polymer particles (solid content concentration 40% by weight) A coated paper was produced in exactly the same manner as in Example 3, except that a coated paper (with an outer diameter of 0.5 μm) was used. The evaluation results are shown in Table 3.

Comparative Example 2 Instead of hollow polymer particles, 65 parts by weight of styrene, 25 parts by weight of methyl methacrylate, 7 parts by weight of acrylonitrile,
Anionic hollow polymer obtained by physically foaming polymer particles consisting of 3 parts by weight of itaconic acid (solid content concentration 40% by weight, outer diameter 0.5μ shoulder, inner diameter 0.3μ resistance) A coated paper was produced in exactly the same manner as in Example 4. The evaluation results are shown in Table 3.

Comparative Example 3 Example 5 except that no hollow polymer particles were used.
Coated paper was produced in exactly the same manner.

The evaluation results are shown in Table 3.

Claims (1)

[Scope of Claims] 1. Polymer particles having an outer diameter of 0.05 to 100 μm and having hollow pores with a diameter of 1 to 99% of the outer diameter,
Amphoteric hollow polymer particles characterized by having a pH of 3 to 9 that provides a precipitation point. 2. By two-stage emulsion polymerization, core/shell type polymer particles having a core swollen by an inert liquid containing an amphoteric emulsifier are formed, followed by a foaming treatment and, if necessary, a treatment for removing the inert liquid. Claim 1 characterized by
A method for producing the amphoteric hollow polymer particles described above. 3. A paper coating composition comprising an inorganic pigment and the amphoteric hollow polymer particles according to claim 1 in an amount of 0.1 to 50% by weight based on the inorganic pigment.