JPH0673138A - Emulsion particle having space - Google Patents

Abstract

PURPOSE:To obtain the subject particle excellent in stability and viscosity and useful as an organic pigment for coating paper, etc., by forming shells on a core particle having an acidic functional property under a specific condi tion, and subsequently subjecting the particle to neutralizing and swelling treatments. CONSTITUTION:(B) A vinylic monomer mixture containing 0-10wt.% of an acidic functional vinylic monomer is added and polymerized in a weight of 2-10 times that of a component A in the presence of (A) core particles comprising a polymer produced by the emulsion polymerization of a vinylic monomer mixture containing 5-80wt.% of an acidic functional vinylic monomer to form the primary shell on the outer layers of the core particles. (C) A vinylic monomer mixture not containing the acidic functional vinylic monomer is added in an amount of 1-7 times that of the component B together with 0.1-10wt.% of a nonionic surfactant having an HLB of 10-18 and polymerized to form the secondary shell. The particles are mixed with a nonvolatile base for their neutralization, swollen and subsequently dried to provide the objective particles having particle diameters of 0.1-5.0mum.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to general coated paper, paperboard,
Useful as an organic pigment added to coating agents used for light-weight coated paper, ultra-light-weight coated paper, art paper, cast coated paper, etc.
The present invention relates to novel emulsion particles having voids inside when dried, a coating composition for paper coating and a coating composition containing the same.

[0002]

2. Description of the Related Art In recent years, as organic pigments added to various coating agents, emulsion particles having voids inside the particles when dried have received much attention. Particles having these voids are said to exhibit superior performance to conventional solid-type particles in terms of hiding power, whiteness and luster, as well as their heat insulating properties and weight reduction effects, and their preparation methods are also various. It is disclosed. Japanese Examined Patent Publication No. 3-9124 discloses
At least one monoethylenically unsaturated sheath monomer forming a sheath polymer is added to a polymer dispersion obtained by copolymerizing at least 5% of an unsaturated carboxylic acid as a core substance,
A core polymer in emulsion particles obtained by emulsion polymerization, by neutralizing and swelling with a volatile base such as ammonia, a method for producing an aqueous dispersion that forms fine voids in the particles when dried is disclosed. There is. The particles prepared by this method have improved the hiding power as organic pigments to some extent, but have the following problems. That is, since a volatile base such as ammonia or amine is used as the neutralizing agent, the viscosity of the coating solution becomes poor in line coating such as in the field of paper coating. In particular, the viscosity under a high shearing force becomes remarkably high, and it cannot be used for high-speed coating using a blade coater in recent years. Also,
The stability as an emulsion is also poor, and it has been pointed out that when it is used as a mixture with an inorganic pigment or a water-soluble binder, it shows an aggregation tendency over time, and the viscosity of the coating solution remarkably increases. . Also, during actual handling,
And the ammonia odor or amine odor of the paint containing it is extremely strong, which is a very big problem. Furthermore, if the swelling ratio of the core is increased to obtain a large porosity, the thinned sheath polymer part is easily deformed due to the plasticizing action of ammonia or amine, and it is difficult for the particles themselves to maintain a spherical shape. There is also a problem that the porosity is reduced as a result. Japanese Patent Publication No. 1-37401 discloses a method for reducing the above-mentioned odor, in which a basic substance is changed to a non-volatile base such as sodium hydroxide so that the non-volatile base can easily permeate the outer layer part of the particle. It is disclosed that substantially 5% by weight or more of an unsaturated carboxylic acid is added to the polymerization of the outer layer portion, or a certain organic solvent is added during the swelling treatment with a basic substance. Although the hollow particles prepared by this method certainly show a great improvement in odor, they cause a new problem. That is, in order to increase the permeability of the non-volatile base, since a very large amount of carboxyl groups are introduced into the outer layer part as compared with normal emulsion particles, the outer layer part is formed during the treatment of the non-volatile base. Some of the existing polymer dissolves in the aqueous phase, causing problems with foaming and stability. Further, if the method of adding the organic solvent is adopted, not only the application range is narrowed but also another odor is given to the obtained emulsion. Japanese Patent Laid-Open No. 64-48
No. 805 discloses a method for producing hollow particles that do not contain the above unsaturated carboxylic acid or organic solvent during polymerization of the outer layer portion. However, in the method described in that application,
It is very difficult to coat a highly hydrophilic core with a highly hydrophobic polymer, so when treated with a non-volatile basic substance, the inside of the particles with small pores during drying is Practical hollow particles cannot be obtained because swelling rather than swelling occurs in the core portion exposed on the particle surface. Even if the hydrophobic polymer is coated, the practically practical hollow particles cannot be obtained because the permeability of the basic substance is extremely low.

[0003]

DISCLOSURE OF THE INVENTION An object of the present invention is to provide a drying agent which is useful as an organic pigment to be added to a coating agent used for paper coating agents, paints, etc., which has reduced odor and is excellent in viscosity and stability. Another object is to provide novel emulsion particles having voids inside the particles.

[0004]

Means for Solving the Problems As a result of intensive studies to solve the above problems, a new emulsion particle having voids inside the particles during drying, which can solve the above problems, was found, and the present invention was completed. Came to. That is, the present invention is
A core layer made of a polymer (A) prepared by polymerizing a vinyl monomer mixture (a) containing 5 to 80% by weight of an acid functional vinyl monomer, and 0 to 1 of an acid functional vinyl monomer.
Primary shell layer composed of polymer (B) prepared by polymerization of vinyl monomer mixture (b) containing 0% by weight, vinyl monomer mixture (c) containing no acid functional vinyl monomer Prepared by polymerizing HLB10 to 18 in the presence of a nonionic surfactant, and composed of a non-volatile base-permeable secondary shell layer made of a polymer (C) having a glass transition temperature of 50 ° C. or higher. Emulsion particles having a particle size of 0.1 to 5.0 μm, which has voids inside the particle when dried as a result of the addition of a non-volatile base to neutralize the core and swell by hydration. Regarding

The acid functional vinyl monomer contained in the vinyl monomer mixture (a) in an amount of 5 to 80% by weight includes acrylic acid, methacrylic acid, crotonic acid, fumaric acid, itaconic acid, maleic anhydride, Examples of the unsaturated carboxylic acid include maleic acid monoalkyl ester and fumaric acid monoalkyl ester. Here, if the content of the acid-functional vinyl monomer exceeds 80% by weight, it becomes difficult to stably prepare the core particles made of the polymer (A), and if it is less than 5% by weight, The porosity decreases,
Practical particles cannot be obtained. Other vinyl monomers to be combined with the acid-functional vinyl monomer include methacrylic acid esters such as methyl methacrylate, ethyl methacrylate, and butyl methacrylate, methyl acrylate, butyl acrylate, and 2-ethylhexyl acrylate. Acrylic esters, vinyl ester-based monomers such as vinyl acetate, aromatic vinyl monomers such as styrene, α-methylstyrene and vinyltoluene, vinyl cyan-based monomers such as (meth) acrylonitrile, vinyl chloride , Vinylidene chloride and other halogenated vinyl monomers and butadiene and other diene-based monomers and divinylbenzene, ethylene glycol di (meth) acrylate, trimethylolpropane trimethacrylate and other crosslinkable vinyl monomers, and further (meth) 2-hydroxyethyl acrylate ,
Functional vinyl monomers such as (meth) acrylamide and N-methylol (meth) acrylamide can be exemplified, and one kind or a combination of two or more kinds is used. The vinyl monomer mixture (b) is polymerized in the presence of particles of the polymer (A) prepared by polymerizing the vinyl monomer mixture (a) containing the acid-functional vinyl monomer. As a result, the polymer (B) is formed as a primary shell on the outer layer portion of the polymer (A). here,
The vinyl monomer mixture (b) contains 0 to 10% by weight of the acid functional vinyl monomer exemplified above, preferably 0 to 5% by weight, more preferably 0 to 2% by weight. Is. When the acid-functional vinyl monomer is contained in an amount of more than 10% by weight, it becomes difficult to form a secondary shell composed of the polymer (C) described below on the outer layer portion of the primary shell, and further, During the treatment with the non-volatile base, a part of the polymer (B) is eluted into the aqueous phase, making it difficult to obtain emulsion particles, which is the object of the present invention.

Other vinyl monomers to be combined with the above acid-functional vinyl monomer include methacrylic acid esters such as methyl methacrylate, ethyl methacrylate and butyl methacrylate, methyl acrylate, butyl acrylate,
Acrylic esters such as 2-ethylhexyl acrylate, vinyl ester monomers such as vinyl acetate, aromatic vinyl monomers such as styrene, α-methylstyrene and vinyltoluene, vinyl cyan monomer such as (meth) acrylonitrile Monomers, vinyl halides such as vinyl chloride and vinylidene chloride, diene-based monomers such as butadiene, and crosslinkable vinyl monomers such as divinylbenzene, ethylene glycol di (meth) acrylate, and trimethylolpropane trimethacrylate. Furthermore, functional vinyl monomers such as 2-hydroxyethyl (meth) acrylate, (meth) acrylamide, and N-methylol (meth) acrylamide can be exemplified, and one kind or a combination of two or more kinds is used. To be done. The vinyl monomer that constitutes the above vinyl monomer mixture (b) is not particularly limited, but since it is formed as a primary shell in the outer layer portion of the particles composed of the polymer (A), it has a hydrophilic property. It is preferable to contain high methyl methacrylate in an amount of 50% by weight or more. The amount of the vinyl monomer mixture (b) added is preferably 2 to 10 times the weight of the polymer (A), but the addition amount of the polymer (A) and the polymer (B) is not limited. It may be slightly changed before and after due to the relationship of hydrophilicity / hydrophobicity. By polymerizing the vinyl monomer mixture (c) in the presence of emulsion particles having a core / primary shell structure composed of the above polymer (A) / polymer (B),
The polymer (C) is formed as a secondary shell on the outer layer portion of the polymer (B). Here, as the vinyl monomer mixture (c), vinyl monomers other than acid-functional vinyl monomers can be exemplified, and methacrylic acid esters such as methyl methacrylate, ethyl methacrylate, and butyl methacrylate can be used. , Acrylic acid esters such as methyl acrylate, butyl acrylate and 2-ethylhexyl acrylate, vinyl ester monomers such as vinyl acetate, aromatic vinyl compounds such as styrene, α-methylstyrene and vinyltoluene, (meth ) Vinyl cyanide monomers such as acrylonitrile, vinyl halide compounds such as vinyl chloride and vinylidene chloride and diene compounds such as butadiene, and cross-linking properties such as divinylbenzene, ethylene glycol di (meth) acrylate, and trimethylolpropane trimethacrylate. Monomer, (meta) Acrylic acid 2-hydroxyethyl, (meth) acrylamide, N- methylol (meth) that a combination of one or more among functional vinyl monomers such as acrylamide are used.

The glass transition point of the polymer (C) thus formed is 50 ° C. or higher, preferably 70 ° C. or higher. If the temperature is lower than 50 ° C., fusion between particles and deformation of the particles themselves easily occur, making it difficult to use as an organic pigment, and if the temperature is further lowered, the desired particles themselves cannot be obtained. From the above glass transition point and the high refractive index of the organic pigment, the vinyl monomer mixture (c) preferably contains styrene in an amount of 50% by weight or more, more preferably 80% by weight. % Or more. Further, in order to form the polymer (C) on the outer layer portion of the polymer (B) forming the primary shell, acrylamides are preferably used, and methacrylamide is particularly preferably used. The addition amount of the vinyl monomer mixture (c) selected as described above is 1 to 7 times, and more preferably 2 to 7 times, the weight of the polymer (B). The above-mentioned vinyl monomer mixture (c) is polymerized in the coexistence of HLB10 to 18 nonionic surfactants. Here, when the HLB of the surfactant is less than 10, the stability at the time of polymerization is lowered and aggregates are easily generated. On the other hand, when the HLB is 18 or more, the polymerization stability is improved, but the voids of the obtained emulsion particles are small, and the performance as an organic pigment is deteriorated. Here, examples of the nonionic surfactant added during the polymerization of the vinyl monomer mixture (c) include polyoxyethylene alkyl ether, polyoxyethylene alkyl allyl ether, ethylene oxide-propylene oxide block copolymer, and sorbitan. Fatty acid esters, polyoxyethylene fatty acid esters, glycerin fatty acid esters, alkylalkanolamides and the like are used alone or in combination. Here, it can be used other than those exemplified as long as it is within the above HLB range, and is not particularly limited. In addition, the concept of the nonionic surfactant,
It also contains a nonionic reactive surfactant having a polymerizable vinyl group in its molecule.

The amount of the nonionic surfactant added is 0.1 to 10% by weight, preferably 1 to 7% by weight, based on the vinyl monomer (c). If the amount added is less than 0.1% by weight, the effect of addition is not recognized and large voids cannot be obtained. On the other hand, if it is added in an amount of more than 10% by weight, foaming of the prepared emulsion becomes remarkable, which is not practical. By adding a non-volatile base to the core / primary shell / secondary shell type emulsion particles having the above constitution, the secondary shell layer permeates the non-volatile base, and the base neutralizes and hydrates the core. As a result of swelling, emulsion particles having voids inside the particles can be obtained during drying. still,
The emulsion particles of the present invention have a particle size of 0.1 to 5.0 μm.
And is preferably 0.1 to 3.0 μ. here,
It is difficult to prepare particles having internal voids when dried, which have a particle size of less than 0.1 μ and more than 5.0 μ. The above emulsion particles are usually prepared by an emulsion polymerization method. Usually, when emulsion polymerization is performed, a surfactant is added, but the vinyl monomer mixture (a) of the present invention,
Examples of the surfactant used in the polymerization of (b) and (c) include anionic surfactants such as sodium alkylbenzenesulfonate, sodium alkylsulfate, sodium dialkylsulfosuccinate, and formalin condensate naphthalenesulfonate. Can be used alone or in combination. The amount of the surfactant used is not particularly limited, but is usually about 0.05 to 1% by weight with respect to the amount of the monomers used between the layers. In addition, also in the polymerization of the vinyl monomer (c) to which the above-mentioned nonionic surfactant is added, there is no problem in using the above surfactant together.

The polymerization initiator may be any of those commonly used in emulsion polymerization, and examples thereof include persulfates such as potassium persulfate, sodium persulfate and ammonium persulfate; organic compounds such as benzoyl hydroperoxide. Peroxides: azo compounds such as azobisisobutyronitrile. If necessary, it can be used as a redox initiator in combination with a reducing agent.
In order to prepare core emulsion particles composed of the polymer (A), various monomers are collectively, divided, or in the presence of the above-mentioned surfactant and polymerization initiator, and optionally a buffer, or Polymerization is carried out by continuously dropping. At that time, the polymerization is carried out at a polymerization temperature of 20 to 90 ° C. under a nitrogen purge. Next, in the presence of the above-mentioned particles composed of the polymer (A), the vinyl monomer (b) and then the vinyl monomer (c) are polymerized by a method of batchwise, divided, or continuous dropping. Done. In addition, as a separate step, core emulsion particles composed of the polymer (A) are produced in advance, and the core emulsion is newly charged into a polymerization tank as seed particles to obtain a vinyl monomer (b) and a vinyl monomer ( Polymerization and treatment may be performed by adding c) as described above. Further, at the time of polymerizing the polymer (A), a conventionally known seed emulsion polymerization method may be used for the purpose of accurately adjusting the particle size, and the composition of the seed at this time is not particularly limited. The preparation of such a polymer (A), polymer (B), and polymer (C) may be carried out subsequently in one step, or in separate steps or in a combined step, There is no particular limitation. After the above-mentioned polymerization process, a non-volatile basic substance is added, and the polymer (A) is neutralized and swelled. The non-volatile base used is not particularly limited as long as it is a general inorganic basic substance such as sodium hydroxide or potassium hydroxide.
The pH at the start of treatment with a basic substance is usually 8 to 12,
It is preferably carried out in the range of 9 to 11. Here, if the pH at the start of the treatment is less than 8, sufficient neutralization swelling does not occur,
If it exceeds 12, the stability of the emulsion tends to be impaired. The temperature during the treatment is usually 50 ° C or higher, preferably 70 to 100 ° C, more preferably 80 to 95 ° C.
Is. If it is less than 50 ° C, the neutralization and swelling treatment cannot be effectively performed because the outer layer is insufficiently plasticized. Through the above steps, during the intended drying, an emulsion particle having a core particle inside the particle and further having a void layer in the core particle outer layer part is obtained, but the structure is the particle itself, and further the cross section of the particle. By observing with an electron microscope,
Easy to check. Emulsion particles having voids inside during the above drying exhibit excellent performance as a pigment, and when used in a paper coating composition, a coating composition, gloss,
It becomes possible to obtain the composition having not only the whiteness and the opacity but also the odor and the stability which are remarkably improved.

The coating composition for paper coating and the coating composition will be described below. The coating composition for paper coating of the present invention comprises a binder, an inorganic pigment and / or a filler, emulsion particles having voids inside when dried according to the present invention as an organic pigment, and further dispersed as an auxiliary agent if necessary. Agents, dyes such as bluing agents, viscosity modifiers, defoamers, and release agents can be added. As the binder, styrene-
Water-based binders such as butadiene-based, styrene-methyl methacrylate-butadiene-based synthetic resin latex, acrylic-based, acrylic-styrene-based, vinyl acetate-based synthetic resin emulsions; starch, modified starch, casein, polyvinyl alcohol Examples of the binder include a binder. These binders may be used alone or in combination of two or more kinds, but synthetic resin latex may be used alone in view of hiding property, whiteness, gloss, viscosity, etc., or may be used in combination with starch or casein. It is preferable. The amount of binder used here is from 4 to 30% by weight, preferably from 6 to 20% by weight, based on all pigments including organic pigments. If the amount of the binder used is less than 4% by weight, a coating layer having practical strength cannot be obtained. If it exceeds 30% by weight, problems such as blocking occur. Examples of the inorganic pigment include kaolin clay, calcium carbonate, talc, satin white, titanium dioxide and the like. The amount of the emulsion particles having voids inside when used as an organic pigment in the present invention is not particularly limited as long as it is 1% by weight or more in the total pigment, but preferably 2 to 70% by weight, more preferably 3%. ~ 30% by weight. Here, if the amount of the particles used is less than 1% by weight, the effect of addition is not recognized. still,
When blending the binder and pigment as described above, the pH is adjusted to 7 or more with a basic substance to stabilize the system, but the basic substance used is sodium hydroxide, potassium hydroxide, or the like. The non-volatile base of is preferable in terms of viscosity. The coating composition for paper coating of the present invention is a paper or paperboard,
Furthermore, it is coated on a plastic sheet etc.,
Coating is a size press coater, gate roll coater,
It is carried out by a usual method such as an air knife coater and a blade coater. Obtained as above,
The coating composition for paper coating of the present invention is excellent in odor, viscosity, suitability for high-speed coating, and stability, and the coating layer obtained from the composition is excellent in gloss, hiding power and whiteness.

The coating composition of the present invention comprises a binder, an inorganic pigment and / or a filler, and emulsion particles having voids inside when dried according to the present invention as an organic pigment,
Further, if necessary, various additives such as a film-forming aid, a plasticizer, a thickener, a pigment dispersant, an antifreezing agent, a pH adjusting agent, a defoaming agent, an antiseptic and a wetting agent can be added. The binder is not particularly limited as long as it can bond the pigment and the filler, but in comparison with the above-mentioned coating composition for paper coating,
Since more water resistance is required, it is preferable to use a water-dispersed binder such as an acrylic, acrylic-styrene, or vinyl acetate-based synthetic resin emulsion, or a styrene-butadiene-based synthetic resin latex. On the other hand, as the inorganic filler and pigment,
Kaolin clay, calcium carbonate, titanium dioxide and the like can be exemplified. The amount of the emulsion particles having voids inside when used as an organic pigment when dried according to the present invention is:
There is no particular limitation as long as it is 1% by weight or more in all pigments, but preferably 2 to 90% by weight, more preferably 3 to 8%.
It is 0% by weight. Here, if the amount of the particles used is less than 1% by weight, the effect of addition is not recognized. The additives that can be added to the coating composition of the present invention include cellosolve, butyl cellosolve, carbitol, butyl carbitol, solosolve acetate, carbitol acetate, texanol and other film-forming aids; dioctyl phthalate, dioctyl. Examples thereof include plasticizers such as adipate; pigment dispersants such as polycarboxylic acid salts; thickeners such as hydroxyethyl cellulose and carboxymethyl cellulose; antifreezing agents such as ethylene glycol and propylene glycol. Here, the pH is adjusted to 7 or higher for the purpose of stabilizing the paint, and the basic substance used is ammonia, trimethylamine, 2-amino-
Examples thereof include volatile bases such as 2-methylpropanol, and non-volatile bases such as sodium hydroxide and potassium hydroxide. However, when water resistance of the coating composition is important, the volatile base also gives off odor. In case of importance, it is preferable to use the latter non-volatile base. The coating composition of the present invention can be appropriately diluted with water, if necessary, and applied by a conventional method such as brush coating, roller coating, or spray coating.

[0012]

EXAMPLES Specific examples of the present invention will be described below, but the present invention is not limited thereto. All parts and percentages below are parts by weight and percentages by weight. Here, the refractive index n and the glass transition point Tg of the polymer are as follows (POLYMERHANDBOOK 2nd Ed., E
d. by J. BRANDRUP and EH IMMERGUT, JOHN WILLEY
& SONS, 1975) and the glass transition point Tgi of each homopolymer and the weight fraction xi of each homopolymer added during the polymerization were calculated according to the following formula. It should be noted that, when the reactive surfactant was used in the present invention, the glass transition point was considered to have no great influence and was ignored in the calculation. (1 / Tg) = Σ (xi / Tgi) Polymerization Example 1 A separable flask equipped with a stirrer, a thermometer, and a reflux condenser is charged with 2200 parts of water, and the temperature is raised to 80 ° C while substituting with nitrogen. Maintaining the internal temperature at 80 ° C., adding 0.5 parts of ammonium persulfate as a polymerization initiator, and after dissolution,
An emulsion equivalent to 0.5% of the emulsion prepared by previously adding 50 parts of water, 0.2 part of sodium lauryl sulfate to 50 parts of methyl methacrylate, 10 parts of butyl acrylate, and 40 parts of methacrylic acid was prepared. After adding and reacting for 30 minutes,
The remaining emulsion is continuously added over 3 hours for reaction, and aging is carried out for 2 hours after the addition is completed. Subsequently, 9 parts of ammonium persulfate dissolved in 70 parts of water was added, and then, an emulsion prepared by adding 630 parts of methyl methacrylate and 70 parts of styrene to 350 parts of water and 0.6 part of sodium lauryl sulfate in advance with stirring. The product is continuously added and reacted for 3 hours, and aging is carried out for 1 hour after the completion of the addition. Subsequently, 2.8 parts of ammonium persulfate dissolved in 28 parts of water was added again, and then 600 parts of water, 5.6 parts of sodium lauryl sulfate, 1330 parts of styrene, and 4 parts of methacrylamide 4 were previously added.
An emulsion prepared by adding 2 parts, 28 parts of 2-hydroxyethyl methacrylate, 28 parts of Emulgen 913 (manufactured by Kao; polyoxyethylene nonylphenyl ether (HLB: 14.5)) under stirring for 3 hours continuously. Then, the reaction is carried out, and aging is carried out for 2 hours after the completion of the addition. Here, the glass transition point of the polymer (C) prepared is 101 ° C.
Subsequently, 80 parts of a 20% aqueous sodium hydroxide solution is added to the above emulsion, and the mixture is held for 3 hours for swelling. The obtained emulsion had a non-volatile content of 40% and a particle diameter D of 0.51 μm, and a void having a diameter of 0.28 μm was confirmed by observation with a transmission electron microscope.

Polymerization Examples 2 to 5 Polymerization Examples 2 to 5 were prepared by changing the amount and type of the nonionic surfactant added during the polymerization of the vinyl monomer (c) in Polymerization Example 1. Is shown in Table-1. Polymerization Comparative Example 1 Polymerization Comparative Example 1 was a case in which the nonionic surfactant was not added during the polymerization of the vinyl monomer (c) in Polymerization Example 1. Polymerization Comparative Example 2 The results of Polymerization Example 1 prepared by changing the basic substance to ammonia are shown in Table 1. The electrolyte stability of the emulsion particles prepared as described above was evaluated. The measurement was performed by dropping 0.1 cc of the emulsion into 10 cc of an aqueous calcium chloride solution whose concentration was continuously changed, and reading the concentration at which generation of aggregates was visually confirmed. The results are also shown in Table-1.

[0014]

[Table 1]

[Paper Coating Composition Example] The emulsion particles shown in the above-mentioned polymerization examples and polymerization comparative examples were evaluated as the organic pigments of the paper coating with the following formulation. [Compound] ───────────────────────────── UW-90 [EMC] 90 parts Emulsion particles 10 parts Aron T-40 [Toagosei Kagaku Kogyo] 0.09 parts MS-4600 [Nippon Shokuhin Kogyo] 3 parts Polylac 755 [Mitsui Toatsu Chemicals] 12 parts ───────────────── ──────────── Coating liquid solid content 62% The coating liquid is prepared by adding Alon T-40, which has a solid content of 40% as a dispersant, to water and kaolin with a Cowles mixer. Clay UW-90 was sufficiently dispersed, and as a binder, phosphoric esterified starch MS-4600, solid content 50
% Styrene-butadiene latex polylac 75
5 was added, and the above emulsion particles were added as an organic pigment. The above coating solution is applied to a high-quality paper with an applicator so that the dry coating amount is about 14 to 15 g / m ² , dried at 120 ° C for 20 seconds, and then a calender roll at a roll temperature of 60 ° C. Linear pressure 70kg
/ Cm and the speed was 10 m / min. The coated paper was obtained by passing the paper twice. The evaluation method is shown below. Color viscosity: Measured with BM type viscometer (60 rpm, No.4
Rotor) High shear viscosity: Measured by Hercules rheometer (8800 rpm) White paper gloss: 75 ° according to JIS P-8142
Measure reflectance at. Printing gloss: Toyo Ink New Bright Indigo 0.4
Printed by RI printing tester using cc. JIS after drying
Measure 75 ° reflectance according to P-8142. Whiteness: Measured with a Hunter whiteness meter according to JIS P-8123. White paper opacity: Measured according to JIS P-8138. The evaluation results are shown in Table-2.

[0016]

[Table 2]

[Example of coating composition] The emulsion particles prepared in the above-mentioned polymerization examples and polymerization comparative examples were used as organic pigments, and a part of rutile type titanium dioxide was replaced to formulate a coating composition. At that time, Almatex E-208, an acrylic emulsion having a resin solid content of 45%, was used as a vehicle for coating material. The paint formulation is shown below. [Compound] ──────────────────────────────────── Water 45.0 parts 25% Tamol 731 aqueous solution ( Rohm & Haas) 12.2 parts Ethylene glycol 40.0 parts 2-Amino-2-methylpropanol 3.0 parts Nopco DF-122NS (manufactured by San Nopco) 0.8 parts Rutile titanium dioxide 164.5 parts Emulsion particles ( 40%) 102.8 parts Almatex E-208 (manufactured by Mitsui Toatsu Kagaku) 676.0 parts Butyl cellosolve / texanol (1/2) mixed solvent 40.0 parts Hydroxyethyl cellulose / propylene glycol (1/10) mixed solution 12 .4 parts ──────────────────────────────────── Paint solids 46.9% PWC (solids) Pigment weight% in) 40 Preparation 0% paint viscosity 70~80KU paint, water, Tamol 731, ethylene glycol, 2-amino-2-methylpropanol, Nopco DF
-122NS, rutile type titanium dioxide was sufficiently dispersed with a pigment disperser, and then emulsion particles prepared in Polymerization Examples or Polymerization Comparative Examples, and ALMATEX E-208,
Butyl cellosolve / texanol and hydroxyethyl cellulose / propylene glycol were added with stirring to prepare a coating composition such that the total Stormer year was 70 to 80 KU. The resulting paint is applied to a slate plate and the dry film thickness is 40μ.
It was applied with an applicator so that it would become, and after one week of drying at room temperature, evaluation was performed. Each evaluation method is shown below. Gloss: Measured at an angle of 75 ° with a Suga Test Instruments gloss meter. Concealment rate: Measured according to JIS K-5663. It was coated using a hiding power test paper manufactured by Japan Test Panel Industry with an applicator so that the dry film thickness was 75 μ, and after one week of drying at room temperature, it was calculated from the reflectance ratio of 45 ° / 0 °. Ammonia odor: The odor of the paint formulation was judged as ◯: Weak, X: Yes. The evaluation results are shown in Table-3.

[0018]

[Table 3]

[0019]

INDUSTRIAL APPLICABILITY The novel emulsion particles having voids inside when dried according to the present invention are excellent in odor, stability, viscosity and the like, and are useful organic pigments to be added to coating agents used for paper coatings and coatings. Can be used in a wide range.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Ms. Yanagihara Mitsui Toatsu Chemical Co., Ltd. 1190 Kasama-cho, Sakae-ku, Yokohama-shi, Kanagawa

Claims (9)

[Claims] 1. 5 to 80% by weight of acid functional vinyl monomer
Core layer made of polymer (A) prepared by polymerization of vinyl monomer mixture (a) containing, vinyl monomer mixture (b) containing 0 to 10% by weight of acid functional vinyl monomer
The primary shell layer made of the polymer (B) prepared by the polymerization of 1., the vinyl monomer mixture (c) containing no acid functional vinyl monomer, and the presence of the nonionic surfactant of HLB 10-18. A non-volatile base made of a polymer (C) having a glass transition temperature of 50 ° C. or higher prepared by polymerization below is formed of a secondary shell layer which is permeable, and by adding the non-volatile base, As a result of the base neutralizing the core and swelling by hydration, emulsion particles having a particle size of 0.1 to 5.0 μm having voids inside the particle when dried. 2. The nonionic surfactant is added in an amount of 0.1 to 10 parts by weight based on the vinyl monomer (c).
The emulsion particles described. 3. The emulsion particles according to claim 1, wherein the nonionic surfactant is a reactive surfactant having a polymerizable vinyl group. 4. The emulsion particles according to claim 1, wherein the vinyl monomer mixture (b) contains 50% by weight or more of methyl methacrylate. 5. Emulsion particles according to claim 1, wherein styrene is contained in the vinyl monomer mixture (c) in an amount of 50% by weight or more. 6. The (meth) in the vinyl monomer mixture (c).
The emulsion particles according to claim 1, which contain 1 to 10% by weight of acrylamide. 7. An acid functional vinyl monomer in an amount of 5 to 80% by weight.
Monomer of vinyl containing 0 to 10% by weight of an acid functional vinyl monomer in the presence of core particles composed of the polymer (A) prepared by emulsion-polymerizing the vinyl monomer mixture (a). The body mixture (b) is added to the polymer (A) in a weight ratio of 2 to 10 and polymerized to form a primary shell composed of the polymer (B) on the outer layer portion of the core particle. Then
Subsequently, the vinyl monomer mixture (c) containing no acid-functional vinyl monomer is added to the vinyl monomer mixture (c) in an amount of 0.1 to 10% by weight of HLB of 10 to 18 and a nonionic property. It is added together with a surfactant in an amount of 1 to 7 times that of the polymer (B) and polymerized to form a secondary shell portion composed of the polymer (C). Subsequently, a nonvolatile base is added to the emulsion. The method for producing emulsion particles having voids inside the particles at the time of drying according to claim 1, which is obtained by performing neutralization and swelling treatment by adding to the particles. 8. A coating composition for paper coating, which comprises the emulsion particle according to claim 1. 9. A coating composition comprising the emulsion particles according to any one of claims 1 to 7.