JP2668909B2 - Alkali-swellable polymer particles, polymer particles having pores inside, and paper coating compositions using these - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention has a pore inside which is useful as a light scattering agent or a light scattering auxiliary which can be used for a coating agent or a paint for paper, fiber, leather or the like. The present invention relates to polymer particles, alkali-swellable polymer particles applicable to the production of the polymer particles, and a paper coating composition using the polymer particles.

[Prior Art] Polymer particles having pores inside the particles are used as microcapsule particles by incorporating various substances into the inner hole, or used as, for example, a light scattering agent by making the inner hole hollow. It is used as an organic material such as hollow polymer particles.

Conventionally, as a method for producing polymer particles having inner pores, (I) a method in which a foaming agent is contained in the polymer particles and the foaming agent is subsequently foamed, (II) volatilization of butane or the like in the polymer (III) dissolving the polymer and spraying a gas jet such as air on this to enclose air bubbles; (IV) polymer particles A method of permeating an alkali-swellable substance into the interior thereof to swell the alkali-swellable substance, (V) a method of preparing a water-oil-water (W / O / W) type monomer emulsion, and performing polymerization, (VI) ) A method in which fine particles of polymethylmethacrylate are used as seed particles and styrene is emulsion-polymerized in the presence of the seed particles. (VII) A suspension of a pigment in an unsaturated polyester solution Process for polymerizing mer, is used, a method for crosslinking polymerization of polymers having different compatibility on the seed particles, and knowing (VIII) crosslinked polymer particles as seed particles.

However, in any of these methods, it is difficult to control the conditions, and it is difficult to reliably produce polymer particles having desired inner pores in good yield. Further, it is difficult to provide a well-balanced physical property required when these particles are added as a light scattering agent to a coating film-forming substance, that is, hiding power, gloss, coating film strength, water resistance, alkali resistance, weather resistance and the like. Is problematic.

[Problems to be Solved by the Invention] The present invention solves the above-mentioned problems of the prior art, has excellent coating properties, and has properties of a coating film, for example, concealing properties,
Polymer particles having an inner pore useful as a film-forming substance having an excellent balance of gloss, coating strength, water resistance, alkali resistance, weather resistance, and the like. It is an object of the present invention to provide an alkali-swellable polymer particle which can be produced, and a paper coating composition using these polymers.

[Means for Solving the Problems] The first invention of the present invention is directed to polymer particles containing 0.5% by weight or more of an unsaturated carboxylic acid monomer as a monomer component.
To 90% by weight of alkali-swellable polymer particles obtained by emulsion polymerization of 10 to 99.5% by weight of a monomer composition satisfying the following conditions (a) and (b).

Conditions: (a) The unsaturated carboxylic acid monomer is contained in a proportion of 1 to 80% by weight based on the monomer composition.

(B) at least one of unsaturated carboxylic acid monomers
The type must have a molecular weight of 100 or more per one carboxyl group.

According to a second aspect of the present invention, the following condition (a) is provided in the presence of 0.5 to 90% by weight of polymer particles containing 5% by weight or more of an unsaturated carboxylic acid monomer as a monomer component.
And 9 to 99.5% by weight of the monomer composition satisfying the condition (b), and then polymerizing the resulting emulsion by neutralizing the resulting emulsion with a base to swell the polymer particles.

Conditions; (a) The unsaturated carboxylic acid monomer is contained in a proportion of 1 to 80% by weight based on the monomer composition.

(B) at least one of unsaturated carboxylic acid monomers
The type must have a molecular weight of 100 or more per carboxyl group.

A third invention of the present invention is the polymer particles 1 to 1 in the first invention or the second invention, preferably the second invention.
Pigment 10 consisting of 50% by weight and 50-99% by weight of a mineral pigment
It relates to a paper coating composition containing 0 parts by weight and 3 to 30 parts by weight of a pigment binder.

That is, in the present invention, polymer particles obtained by polymerizing a monomer composition containing 5% by weight or more of an unsaturated carboxylic acid monomer are used as core particles,
In the presence of ˜90% by weight, a monomer composition for forming a shell 99.5 to 10 satisfying the above conditions (a) and (b).
Emulsion polymerization of wt% forms core-shell type alkali-swellable polymer particles. Then, the polymer particles having internal pores can be produced by swelling the polymer particles by neutralizing with a base.
Further, the polymer particles having the inner pores can be made into a powder state by performing a drying treatment as needed.

All of these polymer particles are useful as film-forming substances such as various coating agents and binders or as an intermediate raw material in the production of toners, but polymer particles having inner pores are particularly excellent as film-forming substances for paper. It is a thing.

In the present invention, the polymer particles constituting the core particles are usually composed of an unsaturated carboxylic acid monomer (A), a nonionic unsaturated monomer (B), and a crosslinkable monomer (C) added as necessary. It is obtained by emulsion polymerization of the monomer composition.

Examples of the unsaturated carboxylic acid monomer (A) include mono- or dicarboxylic acids such as acrylic acid, methacrylic acid, crotonic acid, maleic acid, fumaric acid and itaconic acid, and further, an acid anhydride or monocarboxylic acid of dicarboxylic acid. There are alkyl esters, monoamides and the like, and these can be used alone or in combination of two or more.

The unsaturated carboxylic acid monomer (A) is at least 5% by weight, preferably 8 to 90% by weight, more preferably 10 to 10% by weight, based on the whole monomer composition for constituting the core polymer particles.
Used at a rate of 60% by weight. When the amount of the unsaturated carboxylic acid monomer (A) used is less than 5% by weight, the swelling effect of the alkali is low, and the formation of the inner hole becomes insufficient. It will be inferior. When the amount of the unsaturated carboxylic acid monomer (A) exceeds 90% by weight, the polymer particles are inferior in form such as an irregular shape, and when used as a film-forming substance, have poor water resistance. It is not preferable because the alkali resistance tends to be insufficient.

The nonionic unsaturated monomer includes hydrophilic ones and hydrophobic ones.

As the nonionic hydrophilic unsaturated monomer, methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, methyl methacrylate, 2-
Alkyl esters of acrylic acid or methacrylic acid such as hydroxyethyl acrylate and 2-hydroxyethyl methacrylate; vinyl cyanide compounds such as acrylonitrile and methacrylonitrile; organic acid vinyls such as vinyl acetate, vinyl propionate and vinyl stearate; and vinyl methyl ether , Vinyl ethers such as vinyl ethyl ether, vinyl isobutyl ether and vinyl phenyl ether, acrylamide, methacrylamide, n-methylol methacrylamide, diacetone acrylamide, ethacrylamide, crotonamide, itaconamide, methylitaconamide, maleic monoamide, ethylenediacrylamide Amide monomers such as, β-hydroxyethyl acrylate, β methacrylate
-Hydroxy group-containing monomers such as -hydroxyethyl, n-hydroxyethyl acrylamide, 1-hydroxypropyl acrylate, 1-hydroxypropyl methacrylate, hydroxyethyl acrylate, and hydroxyethyl methacrylate; glycidyl group-containing monomers such as glycidyl acrylate and glycidyl methacrylate; Is mentioned.

As the nonionic hydrophobic unsaturated monomer, aromatic vinyl compounds such as styrene, α-methylstyrene, vinyltoluene and paramethylstyrene, butadiene, isoprene, 2-chloro-1,3-butadiene, 1-chloro-
Examples thereof include aliphatic conjugated diene compounds such as 1,3-butadiene, α-olefins such as ethylene, propylene, butylene, and 4-methylpentene-1, and vinyl halides such as vinyl fluoride and vinyl bromide. These monomers can be used alone or in combination of two or more kinds.

The amount of the nonionic unsaturated monomer used is determined by the balance between the alkali swelling property and the hydrophilicity required for the core polymer particles. The nonionic hydrophilic unsaturated monomer is preferably 10 to 95% by weight, more preferably 20 to 95% by weight, based on the total monomers for forming the core polymer particles.
90% by weight, particularly preferably 40 to 90% by weight, are used. Further, the nonionic hydrophobic unsaturated monomer is preferably, relative to all monomers for forming the core polymer particles,
It is used up to 40% by weight, more preferably up to 20% by weight.

Examples of the crosslinkable monomer (C) include divinyl monomers such as divinylbenzene, ethylene glycol dimethacrylate, 1,3-butylene glycol dimethacrylate, trimethylolpropane trimethacrylate, and allyl methacrylate, or trivinyl monomers. Particularly preferred are divinylbenzene, ethylene glycol dimethacrylate and trimethylolpropane trimethacrylate. The amount of the crosslinkable monomer (C) used is preferably 0.1 to 40 parts by weight based on 100 parts by weight of the monomer composition for forming the core polymer particles.
Parts by weight, more preferably 0.1 to 20 parts by weight. The amount of the crosslinkable monomer (C) used here is calculated as a pure product excluding the inert solvent and the monofunctional non-crosslinkable monomer component normally contained in the crosslinkable monomer material.

The particle size of the polymer particles constituting the core used in the present invention is preferably 0.01 to 1.5 μm, more preferably 0.04 to 1.0 μm, and in the production of the core polymer particles, the solid concentration is preferably 5 to 60 μm. weight%,
It is more preferably 15 to 50% by weight.

The core polymer particles can be produced by usual emulsion polymerization or suspension polymerization. When the target particle size of the polymer particles having alkali swellability or having pores therein is relatively large, it is preferable to use a relatively large particle size of the core polymer particles used for the polymerization. In such a case, the polymer particles obtained by the ordinary one-step polymerization are not used as they are for the core, but the polymer particles obtained by the first-step polymerization are used as seed polymer particles.
It is preferable to use, as the core, one having a larger particle diameter than that of the first stage by performing the second stage polymerization. As the core polymer particles, those produced by repeating one or two stages, or further three or more stages of polymerization as necessary can be used.

The amount of the polymer particles constituting the core is 0.5 to 90% by weight, preferably 0.7 to 60% by weight, more preferably 1.0 to 40% by weight based on the whole polymer. If the amount of the polymer particles constituting the core is less than 0.5% by weight, the formation of inner pores in the finally obtained particles becomes insufficient,
When this is used as a coating film-forming substance, its hiding property becomes poor. If the amount of the polymer particles constituting the core exceeds 90% by weight, not only does the polymerization stability of the system decrease, but also the shape of the particles finally obtained becomes distorted, When used as such, the compounding stability, hiding property, water resistance and alkali resistance of the coating film are inferior.

In the present invention, a monomer composition described below is polymerized in the presence of the polymer particles constituting the core to form core-shell type polymer particles.

As the monomer for forming the shell used in the present invention, an unsaturated carboxylic acid monomer (A ⁻ ), a higher unsaturated carboxylic acid monomer having a molecular weight of 100 or more per carboxyl group (D), a nonionic The unsaturated monomer (B ⁻ ) and the crosslinking monomer (C ⁻ ) used as needed are used.

And the monomer composition for forming the shell is
The following conditions (a) and (b) must be satisfied.

(A) The unsaturated carboxylic acid (A ⁻ ) and the higher unsaturated carboxylic acid (D) are combined together and are 1 to 80% by weight, preferably 2 to 70% by weight based on the monomer composition for forming the shell. , More preferably 10 to 60% by weight. The monomer (A ^-) and the amount of (D) is less than 1 wt%, the concealing property and film strength in the case of using polymerization stability is poor, also the polymer particles obtained as a film-forming substance The balance will be poor. When the amount of the above-mentioned monomers (A ⁻ ) and (D) exceeds 80% by weight, the composition stability, coating property, hiding property and coating property of the obtained polymer particles when used as a film-forming substance. The film has poor water resistance and alkali resistance.

(B) At least one of the unsaturated carboxylic acid monomers uses a higher unsaturated carboxylic acid (D). This higher unsaturated carboxylic acid (D) can be used alone,
Further, it can be used in combination with the unsaturated carboxylic acid (A ⁻ ).
When only the unsaturated carboxylic acid (A ⁻ ) is used without using the higher unsaturated carboxylic acid (D), when the obtained polymer particles are used as a film-forming substance, their gloss, hiding property and coating property are reduced. The film strength is inferior.

The ratio of the unsaturated carboxylic acid (A ⁻ ) to the higher unsaturated carboxylic acid (D) may be any value as long as the above conditions (a) and (b) are satisfied, but it is used as a coating film forming substance. In view of the physical properties such as hiding properties, water resistance, and alkali resistance, the monomer (A ⁻ ) / monomer (D) = 9 /
1 to 0/10, more preferably (A ⁻ ) / (D) = 5/1 to 0/10,
Particularly preferably, (A ⁻ ) / (D) = 4/1 to 0/10.

Examples of the higher unsaturated carboxylic acid (D) include the following.

(R ₁ , R ₂ , R ₃ ; hydrogen atom or alkyl group having 1 to 20 carbon atoms) (R ₄ , R ₅ , R ₆ ; hydrogen atom or an alkyl group having 1 to 12 carbon atoms, EO; ethylene oxide, PO; propylene oxide) (R ₇ , R ₈ ; hydrogen atom or alkyl group having 1 to 20 carbon atoms) The higher unsaturated carboxylic acid (D) is not limited to these, and the molecular weight per carboxyl group is about 100 or more, preferably Is from 150 to 500.

As the unsaturated carboxylic acid (A ⁻ ), the same monomers as the unsaturated carboxylic acid (A) exemplified as the monomer of the polymer particles constituting the core described above can be used. In particular, acrylic acid and methacrylic acid can be used. It can be preferably used.

As the nonionic unsaturated monomer (B ⁻ ), the same one as the nonionic unsaturated monomer (B) exemplified as the monomer of the polymer particles constituting the core described above can be used. Nonionic unsaturated monomer (B ^-) amount of the monomer composition for forming the shell
It is 20 to 99% by weight, preferably 30 to 98% by weight, more preferably 40 to 90% by weight.

As the crosslinkable monomer (C ⁻ ), those similar to the crosslinkable monomer (C) exemplified as the monomer of the polymer particles constituting the core described above can be used.
Including a crosslinkable monomer (C ⁻ ) is preferable in terms of mechanical strength and solvent resistance of the formed polymer particles, and is preferable for a monomer composition for forming a shell.
It is used in a proportion of 0.1 to 20% by weight, more preferably 0.1 to 10% by weight. Crosslinking monomer (C ^-) amount of 30 wt%
When it exceeds, the polymerization stability of the system is lowered and it becomes difficult to produce polymer particles.

The amount of the monomer composition used to form the shell is
10-99.5% by weight, based on the total polymer, preferably 40-9
It is 9.5% by weight, more preferably 60 to 99.5% by weight. If the amount of the monomer composition forming the shell is less than 10% by weight, the formation of the shell is incomplete, while if it exceeds 99.5% by weight, the amount of the polymer constituting the core becomes relatively insufficient. It is difficult to form holes.

An emulsifier and a catalyst are usually used in the polymerization of the alkali-swellable polymer particles of the present invention.

As emulsifiers, anionic surfactants, nonionic surfactants, cationic surfactants, amphoteric surfactants,
Substances having a surface activity such as an organic suspension protective agent can be exemplified, and particularly, an anionic surfactant and a nonionic surfactant can be preferably used. These emulsifiers can be used alone or in combination of two or more.

As the anionic surfactant, potassium rosinate,
Rosinates such as sodium rosinate, sodium or potassium salts of fatty acids such as potassium oleate, potassium laurate, sodium laurate, sodium stearate, potassium stearate, and sulfates of aliphatic alcohols such as sodium lauryl sulfate Examples thereof include salts and alkylallyl sulfonic acids such as sodium dodecylbenzene sulfonate.

Examples of the nonionic surfactant include polyethylene glycol alkyl esters, alkyl ethers, and alkyl phenyl ethers.

Organic suspending agents include polyacrylic acid, polymethacrylic acid, polyvinyl sulfonic acid, polyvinyl alcohol, polyvinyl pyrrolidone, hydrophilic synthetic high molecular substances such as polyethylene glycol, gelatin, and natural hydrophilic high molecular substances such as water-soluble starch And hydrophilic semi-synthetic polymer substances such as carboxymethyl cellulose.

Examples of the polymerization initiator include cumene hydroperoxide, diisopropylbenzene hydroperoxide, organic hydroperoxides represented by paramenthane hydroperoxide and the like, sugar-containing pyrophosphate formulation, sulfoxylate formulation, sugar-containing pyrophosphate formulation. / Redox initiators in combination with reducing agents represented by mixed formulations of sulfoxylate formulations, etc., further, persulfates such as potassium persulfate and ammonium persulfate, azobisisobutyronitrile, benzoyl peroxide, Lauroyl peroxide or the like can be used arbitrarily, particularly preferably potassium persulfate, a sulfite such as ammonium sulfite, azobisisobutyronitrile, a combination of benzoyl peroxide and a reducing agent as necessary. is there.

The polymerization temperature is usually 5 to 95 ° C, preferably 50 to 90 ° C.

Further, the various monomers described above can be added to the system all at once or in divided portions, or continuously by dropping.

The alkali-swellable polymer particles thus obtained are core-shell resin particles and have few inner pores before being neutralized with a base, but the polymer particles are neutralized with a base. The polymer particles having inner pores are obtained by swelling with.

These alkali-swellable polymer particles and polymer particles having internal pores are obtained in the form of a dispersion (emulsion). If necessary, the polymer particles are separated and dried to obtain powdery polymer particles. Can be.

Before drying, the polymer particles having the inner pores are usually in a state in which water is present in the inner pores, and the water in the inner pores is removed by drying to form voids and become hollow polymer particles.

As a method of drying the polymer particles to obtain powdery polymer particles, a commonly used method of pulverizing an emulsion can be used, for example, a spray drying method (135 to 1).
55 ℃), tray drying method using hot air dryer (50-70 ℃)
And a fluidized bed drying method (normal temperature to 70 ° C.) can be used.

The particle size of the alkali-swellable polymer particles is preferably 0.08 to 4 μm, more preferably 0.1 to 3 μm, and the particle size of the polymer particles after neutralization and swelling with a base is preferably 0.09 to 5.7 μm. More preferably 0.1
2 to 4.3 μm. The diameter of the inner hole in the polymer particle having the inner hole is preferably 0.1 to 0.9 times, more preferably 0.2 to 0.8 times, particularly preferably 0.4 to 0.75 times the outer diameter.

The polymer particles of the present invention can be suitably used as a pigment in a paper coating composition. In particular, when the polymer particles having inner pores are used together with the mineral pigment as a part of the pigment of the paper coating composition, the resulting coated paper has concealing properties, gloss,
The balance of physical properties such as surface strength is excellent.

The composition ratio of the mineral pigment and the polymer particles is such that the ratio of the former to the latter is 50 to 99/1 to 50, preferably 60 to 97/3 to 40 by weight. If the content of the latter is less than 1% by weight, sufficient concealing properties, gloss and surface strength cannot be obtained, while if it exceeds 50% by weight, printability is inferior.

As mineral pigments, for example, kaolin clay, talc,
Examples thereof include barium sulfate, titanium oxide (rutile, anatase), calcium carbonate, aluminum hydroxide, zinc oxide, satin white and the like.

As the pigment binder, any binder can be used without particular limitation as long as it is a binder used in a usual paper coating composition. As the binder, for example, starch, modified starch, natural binders such as casein, styrene-butadiene-based copolymer latex, carboxy-modified styrene-butadiene-based copolymer latex, polyvinyl acetate emulsion, acrylic polymer emulsion, Examples thereof include synthetic binders such as polychloroprene latex and polyvinyl alcohol.

The above-mentioned binders can be used alone or in combination of two or more. Of these pigment binders, styrene-
It is preferable to use a butadiene-based copolymer latex, particularly a carboxy-modified styrene-butadiene copolymer latex, alone or in combination with a natural binder such as starch or casein.

The binder is used in an amount of 3 to 30 parts by weight, preferably 5 to 25 parts by weight, based on 100 parts by weight of the pigment. If the amount of the binder used is less than 3 parts by weight, the effect as a binder cannot be obtained, while if it exceeds 30 parts by weight, the viscosity of the paper coating composition increases and the coating workability deteriorates. As an auxiliary agent to be added to the paper coating composition, sodium pyrophosphate, sodium hexametaphosphate, a pigment dispersant such as sodium polycarboxylate,
An antifoaming agent such as polyglycol fatty acid ester, phosphoric acid ester, and silicone oil can be added as appropriate.

Examples of the method for applying the paper coating composition onto the base paper include methods such as an air knife coater, a blade coater, and a roll coater.

[Examples] Hereinafter, the present invention will be described more specifically with reference to Examples. In the following description, "parts" and "%" represent parts by weight and% by weight. The polymerization in Examples and Comparative Examples was all performed in a nitrogen gas atmosphere. Also,
The number average particle diameter of the polymer particles and the number average value of the diameter of the inner pores were randomly extracted in observation with an electron microscope.
Based on the measurement results of 100 particles.

(Production of Core Emulsion B-1 to B-7) Core Emulsion B-1, B-3, B-4, B-7 324.4 parts of water and an emulsifier "f-65" in a reaction vessel having a volume of 2 liters (Kao (stock) )) And 0.34 parts of ammonium persulfate. On the other hand, 46.5 parts of n-butyl acrylate, 36.8 parts of methyl methacrylate, 5 parts of 2-hydroxyethyl methacrylate, 11.7 parts of methacrylic acid, 0.045 part of emulsifier f-65 and 29.8 parts of water are mixed and stirred to prepare a monomer emulsion. . Twenty-one parts of this monomer emulsion was added to the reaction vessel, and the temperature was raised to 85 ° C while stirring in the reaction vessel. While maintaining the reaction vessel at 85 ° C., the remainder of the monomer emulsion was continuously added to the reaction vessel over 2 hours, and aging was performed for 1 hour.

The resulting polymer emulsion is referred to as a seed emulsion A-1.

Next, 300.6 parts of water and 0.6 parts of ammonium persulfate were placed in a reaction vessel.
Part, seed emulsion A-1 obtained by the above method 1.
7 parts were added, and the temperature was raised to 75 ° C. while stirring.

On the other hand, methyl methacrylate 69.6 parts, methacrylic acid 29.9
Parts, ethylene glycol dimethacrylate 0.5 part, emulsifier F-65 0.11 part and water 33.4 parts were mixed and stirred to obtain a monomer emulsion. The temperature of the polymerization system was raised to 85 ° C. while continuously adding this monomer emulsion to the reaction vessel, and the monomer emulsion was added over a total of 2 hours while maintaining the system temperature at 85 ° C. After that, aging was further performed for 1 hour while maintaining the system temperature at 85 ° C. to obtain an emulsion. The emulsion thus obtained is referred to as a core emulsion B-1.

Next, polymerization was carried out in the same manner as in the core emulsion B-1 except that the monomer composition, the polymerization initiator, and the amount (solid content) of the seed emulsion used were as shown in Table 1 to obtain three core emulsions. Obtained.

Add these core emulsions B-3 and B-4, respectively.
And B-7. The core emulsion B-7 does not fall within the scope of the present invention.

Core Emulsion B-2 In the production of the seed emulsion A-1, the amount of the emulsifier F-65 directly added to the reaction vessel at the start of the reaction was adjusted.
Seed emulsion A-1 except changed from 0.6 part to 0.8 part
Polymerization was carried out in the same manner as in the above case.

The obtained polymer emulsion is referred to as a seed emulsion A-2.

Then, the above A-2 was used as a seed emulsion for 3.4
Polymerization was carried out in the same manner as in the case of the core emulsion B-1 except that a part thereof was used to obtain a polymer emulsion.

This polymer emulsion is used as core emulsion B-2.
And

Core emulsion B-5, B-6 To a reaction vessel having a volume of 2 liters, 250 parts of water, 0.2 part of emulsifier F-65, 0.7 part of benzoyl peroxide and 0.1 part of sodium pyrobisulfite were added. Meanwhile, methyl acrylate 15
Parts, n-butyl acrylate 23.5 parts, methyl methacrylate
25.6 parts, acrylonitrile 10 parts, diethylene glycol dimethacrylate 0.5 parts, methacrylic acid 25.4 parts, emulsifier F
-65 0.11 parts and 33.4 parts of water were mixed and stirred to prepare a monomer emulsion.

10 parts of this monomer emulsion was charged into the reaction vessel, the system was heated to 50 ° C. with stirring, and reacted at 50 ° C. for 30 minutes. After that, the rest of the monomer emulsion was continuously added over a period of 2 hours while maintaining the system at 50 ° C. Further, aging was carried out for 1 hour while maintaining the temperature at 50 ° C. to obtain a polymer emulsion.

This polymer emulsion is used as a core emulsion B-5.
And

Except that the monomer composition and the polymerization initiator in the production of the core emulsion B-5 were changed as shown in Table 1, and the polymerization temperature was changed to 65 ° C., the core emulsion B-5 was used.
Polymerization was carried out in the same manner as in the above to obtain a polymer emulsion.

This polymer emulsion is used as a core emulsion B-6.
And

Example 1 (1) Synthesis of Alkali-Swellable Polymer Particles 150 parts of water and a core emulsion B-1 were placed in a reaction vessel having a volume of 5 l.
5.6 parts (solid content) and 0.39 parts of ammonium persulfate were charged, and the temperature was raised to 85 ° C. while stirring. Meanwhile, styrene
89 parts, higher unsaturated carboxylic acid "V-2000" (manufactured by Osaka Organic Co., Ltd.) 11 parts, water 30 parts and emulsifier "HITENOL N"
o.8 ”(manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) was mixed and stirred to prepare a monomer emulsion. This monomer emulsion was continuously added into the reaction vessel whose internal temperature was kept at 85 ° C. over 3 hours. After addition of the monomer emulsion, aging was carried out at a temperature of 85 ° C. for 1 hour. The average particle size of the alkali-swellable polymer particles in the emulsion thus obtained was 0.52 μm.

(2) Production of polymer particles having inner pores The emulsion of the alkali-swellable polymer particles obtained in (1) was neutralized with 25% aqueous ammonia to adjust the pH to 9.0. The emulsion was then heated at 70 ° C for 2 hours. The number average particle diameter of the polymer particles in the obtained emulsion is 0.55 μm, and the internal number average value is 0.27 μm
It was confirmed to have a hole having a diameter of.

Examples 2-5, Comparative Examples 1-6, 17 Examples except that the amounts of styrene and higher unsaturated carboxylic acid V-2000 used in Example 1 were changed as shown in Table 2 (I) and (II). Polymerization was carried out in the same manner as in Example 1 to produce polymer particles having 4 types of inner pores in Examples and 1 type in Comparative Examples.

 These are Examples 2 to 5 and Comparative Example 17.

In addition, the higher unsaturated carboxylic acid V-2000 in Example 1
In the same manner as in Example 1 except that the polymerization was carried out using methacrylic acid in place of the ratio shown in Table 2 (I), and the heating temperature in the subsequent neutralization / heating treatment was changed to 70 ° C to 90 ° C. Polymer particles having inner pores were obtained.

 These are referred to as Comparative Examples 1 to 6.

Example 6 (1) Production of Alkali-Swellable Polymer Particles 150 parts of water and a core emulsion B-1 were placed in a reaction vessel having a volume of 3 liters.
5 parts (solid content), 0.5 parts of potassium persulfate, and 0.05 parts of sodium hydrogen sulfite were charged, and the temperature was raised to 70 ° C. with stirring. On the other hand, methyl methacrylate 15 parts, styrene 50 parts, methacrylic acid 5 parts, higher unsaturated carboxylic acid V-2000 30 parts,
28 parts of water and 0.1 part of emulsifier Hytenol No. 8 were mixed and stirred to prepare a monomer emulsion.

Then, the monomer emulsion was continuously added over 3 hours while maintaining the internal temperature of the reaction vessel at 70 ° C. Further, while aging the system at 70 ° C. for 45 minutes, an emulsion of alkali-swellable polymer particles was obtained.

(2) Production of polymer particles having inner pores 25% aqueous ammonia was added to the emulsion obtained in (1) to adjust the pH to 9.2.
Heated for hours. The polymer particles of the obtained emulsion had a number-average particle diameter of 0.53 μm and an inner hole diameter of 0.
It was 30 μm.

Examples 7 to 9, Comparative Examples 15, 16 Alkali-swellable polymer particles were prepared in the same manner as in Example 6 (1), except that the type and amount of the core emulsion were changed as shown in Tables (I) and (II). The resulting emulsion was subjected to neutralization and heat treatment in the same manner as in Example 6 (2) to obtain polymer particles having three kinds of inner pores in Examples and two kinds in Comparative Examples. These were named Examples 7 to 9 and Comparative Examples 15 and 16.

Example 10 (1) Production of Alkali Swellable Polymer Particles 20 parts (solid content) of core emulsion B-3 previously obtained, 0.7 part of benzoyl peroxide, 0.1 part of sodium pyrobisulfite, emulsifier Emal 10N (Kao Corporation )
0.2 parts and 100 parts of water were charged into a reaction vessel having a volume of 5 l, and the temperature was raised to 80 ° C while stirring. Then, 5 parts of acrylonitrile, 26.5 parts of styrene, 38 parts of 1,3-butadiene, 0.5 part of divinylbenzene, 3 parts of itaconic acid, 25 parts of higher unsaturated carboxylic acid "V-2100" (manufactured by Osaka Organic Co., Ltd.), 25 parts of higher grade A monomer composition consisting of 2 parts of unsaturated carboxylic acid “PA-HAMA” (manufactured by Mitsubishi Rayon Co., Ltd.) was continuously added to the reaction vessel for 10 hours while maintaining the temperature of the polymerization system at 65 ° C. to swell with alkali. An emulsion of conductive polymer particles was obtained.

(2) Production of Polymer Particles Having Inner Porosity The emulsion obtained in (1) was adjusted to pH 9.5 by adding 25% aqueous ammonia, and then heat-treated at 60 ° C. for 2 hours. The polymer particles of the obtained emulsion have a number average particle diameter of 0.5 μm and an inner pore diameter of a number average value.
It was 0.35 μm.

Example 11 Polymerization was carried out in the same manner as in Example 10 (1) except that the types and amounts of the monomer and core emulsion in Example 10 (1) were changed as shown in Table 2 (I). Example
Neutralization and heat treatment were performed in the same manner as in 10 (2) to obtain polymer particles having inner pores. The obtained polymer particles have a number average particle diameter of 0.75 μm and a number average value of the diameter of the inner pores of 0.41 μm.
m.

Example 12 (1) Production of Alkali-Swellable Polymer Particles 4.5 parts (solid content) of the core emulsion B-5 obtained earlier, 0.5 parts of ammonium persulfate and 150 parts of water were charged into a reaction vessel, and the mixture was heated to 80 ° C. with stirring. The temperature was raised. On the other hand, n-butyl acrylate 12 parts, methyl methacrylate 15 parts, 2-hydroxyethyl methacrylate 5 parts, N-methylol methacrylamide 4.5 parts, ethylene 27 parts, diethylene glycol dimethacrylate 1.5 parts, acrylic acid 5 parts, higher 30 parts of saturated carboxylic acid "Acryester HH" (manufactured by Mitsubishi Rayon Co., Ltd.), 29.9 parts of water and emulsifier Hitenol
No. 8 0.1 part was mixed and stirred to obtain a monomer emulsion. Then, the monomer emulsion was continuously added to the reaction vessel whose internal temperature was kept at 80 ° C. for 2 hours and 30 minutes,
Polymerization was performed. Further, the temperature of the system was raised to 85 ° C. and aged for 45 minutes.

(2) Production of Polymer Particles with Inner Porosity The emulsion obtained in (1) was adjusted to pH 9.0 by adding 25% aqueous ammonia, and then heat-treated at 80 ° C. for 2 hours. The polymer particles of the emulsion thus obtained had a number-average particle diameter of 0.54 μm and an inner hole diameter of 0.28 μm in number-average value.

Example 13 B was changed from the core emulsion B-5 in Example 12 to B
Polymerization was carried out in the same manner as in Example 12 except that -6 was used, and the obtained emulsion was subjected to neutralization and heat treatment in the same manner as in Example 12 (2) to obtain polymer particles having inner pores. . The polymer particles have a number average particle size of 0.52 μm,
The number average value of the diameters of the inner holes was 0.15 μm.

Comparative Example 7 (1) Production of Alkali-Swellable Polymer Particles 5 parts (solid content) of the core emulsion B-7 obtained previously, 0.4 part of ammonium persulfate and 150 parts of water were added to a volume of 5 liters.
And heated to 85 ° C. while stirring.
On the other hand, methyl methacrylate 15 parts, styrene 53 parts, methacrylic acid 2 parts, higher unsaturated carboxylic acid V-2000 30 parts, water 30
And 0.1 part of emulsifier Hitenol No. 8 were mixed and stirred to prepare a monomer emulsion.

Then, the monomer emulsion was continuously added to a reaction vessel whose internal temperature was kept at 85 ° C. for 3 hours to carry out polymerization. Further, it was aged at 85 ° C. for 45 minutes to obtain an emulsion of alkali-swellable polymer particles.

(2) Production of polymer particles having inner pores The emulsion obtained in (1) was adjusted to pH 9.2 by adding 25% aqueous ammonia, and then heated at 70 ° C. for 2 hours.

The polymer particles of the obtained emulsion had an average particle diameter of 0.59 μm and an inner hole diameter of 0.13 μm as a number average value.

Comparative Examples 8 to 10 Polymerization was carried out in the same manner as in Comparative Example 7 (1) except that the amount of the monomer used in Comparative Example 7 was changed to that shown in Table 2 (II), and the same as in Comparative Example 7 (2). Perform sum and heat treatment, 3
Seed polymer particles were obtained. These are Comparative Examples 8-10. Table 2 (II) shows the number average particle diameter of the polymer particles and the number average value of the inner hole diameter of the polymer particles obtained in Comparative Examples 8 to 10.
Shown in

Example 14 (1) Production of Alkali-Swellable Polymer Particles 5 parts (solid content) of the core emulsion B-2 obtained above, 0.35 part of ammonium persulfate and 125 parts of water were charged into a reaction vessel, and the mixture was heated to 80 ° C. with stirring. The temperature was raised. On the other hand, 15 parts of n-butyl acrylate, 5 parts of 2-ethylhexyl acrylate, 25 parts of methacrylic acid, 15 parts of styrene, 10 parts of methacrylic acid, 30 parts of higher unsaturated carboxylic acid PA-HEMA, 30 parts of water and emulsifier Hitenol No. .8 0.3 part was mixed and stirred to prepare a monomer emulsion. Then, the monomer emulsion was continuously added to the reaction vessel whose internal temperature was kept at 80 ° C. for 3 hours to carry out polymerization. 85 ° C
And ripened for 2 hours to obtain an emulsion of alkali-swellable polymer particles.

(2) Production of Polymer Particles Having Inner Porosity The emulsion obtained in (1) was adjusted to pH 9.5 by adding 25% aqueous ammonia, and then heat-treated at 65 ° C. for 2 hours. The polymer particles of the obtained emulsion have a number average particle diameter of 0.33 μm and an inner pore diameter of a number average value.
0.2 μm.

Examples 15 to 18, Comparative Examples 11 to 14 Polymerization was carried out in the same manner as in Example 14 (1) except that the amount of the monomer used in Example 14 was changed as shown in Table 2 (II), and then Examples Neutralization and heat treatment were carried out in the same manner as in 14 (2) to obtain four types of polymer particles for the examples and four types of polymer particles for the comparative examples. These are Examples 15-18 and Comparative Examples 11-14. Table 2 (II) shows the number average particle diameter and the inner diameter of these polymer particles. In addition, the comparative example
In Nos. 11 to 14, polymerization stability was poor and polymer particles could not be obtained.

Example 19 150 parts of water in a reaction vessel having a volume of 5 liters, core emulsion B-1
5.6 parts (solid content) and 0.39 parts of ammonium persulfate were charged and heated to 85 ° C. with stirring. On the other hand, higher unsaturated carboxylic acid acrylate HH 15 parts, styrene 85 parts, water 30
And 0.1 part of Hitenol No. 8 were mixed and stirred to prepare a monomer emulsion. This monomer emulsion was continuously added over 3 hours into the reaction vessel maintained at an internal temperature of 85 ° C. After addition of the monomer emulsion, aging was carried out at a temperature of 85 ° C. for 1 hour. The pH of the emulsion thus obtained is 2.0, and the average particle size of the alkali-swellable polymer particles is
It was 0.5 μm. This is Example 19.

Example 20 The emulsion of the alkali-swellable polymer particles obtained in Example 19 was neutralized with 25% aqueous ammonia to adjust the pH to 9.0. The emulsion was then heated at 70 ° C for 2 hours. The number average particle diameter of the polymer particles in the obtained emulsion is 0.55 μm, and the number average value is 0.29 μm inside.
It was confirmed to have holes with a diameter of m.

Then, the obtained emulsion of polymer particles having inner pores was placed in a tray and dried at a temperature of 55 ° C. for 5 hours using a hot air drier to obtain white powdery polymer particles.
It was confirmed that the obtained powder had an inner hole.

Example 21 The emulsion of the alkali-swellable polymer particles obtained in Example 19 was dried in the same manner as in Example 20, to obtain white powdery polymer particles.

The structures of the higher unsaturated carboxylic acids used in Examples and Comparative Examples are shown below.

(Application example) Examples 3,6,8,10,15,19-21 and comparative examples 8,15,16,3,1
Using the polymer particles obtained in Nos. 7 and 6, a paper coating composition was prepared according to the formulation shown in (1) below, and a coated paper was prepared under the coating conditions shown in (2). Then, a coating test was performed on the obtained coated paper under the conditions shown in (3). The properties of the polymer particles in each paper coating composition and the results of the coating test are shown in Table 3.

(1) Formulation of composition for paper coating-Pigment (part by weight of solid content) Kaolin clay 60 (Mineral Chemical Phillips) Heavy calcium carbonate 30 Polymer particles 10-Binder latex 0619 (Nippon Synthetic Rubber Co., Ltd.) 13 Starch MS4600 2 (Nippon Shokuhin Kako Co., Ltd.) ・ Dispersant Aron T-40 (Toa Gosei Chemical Co., Ltd.) 0.12 Sodium hexametaphosphate 0.03 ・ Base NH ₄ OH 0.1 ・ Waterproofing agent Sumirez-633 1.3 (Sumitomo) chemical Co., Ltd.) lubricant NOPCOAT C-104 0.1 (San'nopuyu Co.) total solids concentration of 62% (2) coating conditions sheet; commercially available high quality paper (53.7 g / m ²⁾ coating; rod hand Coating Drying: Drying at 120 ° C for 10 minutes with an electric dryer Calendar: Using a super calender method, 50 ° C, 100
Repeat twice under the condition of kg / cm.

(3) Test conditions Dry pick; using an IR printer, perform multiple overprints with ink No. 9 tack, and visually judge the picking state of the printing surface (larger value out of 5 is better) .

Wet pig: Using an IR printing machine, water is supplied on the test piece with a molton roll, and the picking state is judged with the naked eye (the larger the value out of 5 is, the better).

Ink set; Use an IR printer to compare the ink drying properties (out of 5 points, the larger the value, the faster the drying).

White paper gloss; unprinted coated paper using Murayama gloss meter, incident angle
Measure at 75 ° and reflection angle of 75 °.

Printing gloss: The ink for web offset is solid printed using an IR printer, and measured at an incident angle of 75 degrees and a reflection angle of 75 degrees using a Murayama gloss meter.

Whiteness: Measured by a blue filter using a Hunter colorimeter and whiteness meter.

Opacity: Measured with a green filter using a Hunter colorimetric and whiteness meter.

 From the above test results, the following was found.

Comparative Example 8 is an example in which the amount of the unsaturated carboxylic acid monomer in the core polymer particles is less than 5% by weight, and in this example, the swelling property of the core is low, the formation of inner pores is insufficient, and Whiteness when used as a coating composition,
Inferior in opacity.

Comparative Example 15 is a case where the amount of the core polymer particles used is less than 0.5 parts by weight relative to 100 parts by weight of the monomer composition forming the shell, and in this example, there is no swelling ability of the core and it is difficult to form the inner pores. And inferior in gloss, whiteness and opacity when used as a paper coating composition.

Comparative Example 16 is an example in which the amount of core polymer particles used in the monomer composition forming the shell is excessive. In this example, the stability at the time of neutralization and swelling treatment with a base was poor, and gelation occurred at the time of preparation of the paper coating composition, and coating was not possible.

Comparative Example 17 is an example in which the amount of the unsaturated carboxylic acid monomer used in the shell-forming monomer composition exceeds 80% by weight. In this example, the viscosity of the paper coating composition is very high, the coatability is insufficient, and the coating strength, gloss, whiteness and opacity are remarkably inferior.

Comparative Examples 3 and 6 are examples in which the higher unsaturated carboxylic acid monomer was not contained in the shell-forming monomer. In this example, the coating strength, gloss, whiteness, opacity and the like of the paper coating composition are inferior.

Reference Example As described above, titanium oxide “A-220” (manufactured by Ishihara Sangyo Co., Ltd.) was used as a pigment in place of the polymer particles of the present invention for comparison with the paper coating composition of the present invention. Prepare a paper coating composition under the same conditions as in the application example,
Further, a coating test was conducted on the obtained coated paper.

 The results are shown in Table 3 as Reference Example 1.

Further, the case where only kaolin clay was used without using polymer particles as the pigment is referred to as Reference Example 2.

The results of Table 3 revealed the following. That is, the paper coating composition of the present invention is superior in terms of wet pick (coating strength), gloss, hiding power and the like to the case where only kaolin clay is used as a pigment. Further, the paper coating composition of the present invention has physical properties comparable to those in the case of using titanium oxide as a part of the pigment in terms of hiding power (whiteness, opacity), and further has coating strength. In terms of gloss, lightness and lightness, it has properties that surpass these.

EFFECT OF THE INVENTION According to the present invention, a coating film-forming substance having excellent coatability and excellent coating film properties such as hiding power, gloss, coating film strength, water resistance, alkali resistance, and light resistance, Particularly, it is possible to provide polymer particles having inner pores which can be usefully used as a paper coating composition, and further, it is possible to produce the polymer particles by a simple process at a high yield, and to obtain alkali-swellable polymer particles. Can be provided.

The polymer particles of the present invention, particularly the polymer particles having inner pores, can be used in various applications, for example, paints, inks, textile / leather treatment agents, water-absorbent fillers for inkjet paper, internal fillers for papermaking processes, It can be used as a correction ink, a highly opaque pigment for a correction ribbon, a microcapsule material, or an intermediate material of a toner used in electrophotography.

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Claims (4)

(57) [Claims] 1. A monomer composition satisfying the following conditions (a) and (b) in the presence of 0.5 to 90% by weight of polymer particles containing 5% by weight or more of an unsaturated carboxylic acid monomer as a monomer component: 10 to 99.5% by weight. % Of the alkali-swellable polymer particles obtained by emulsion polymerization. Conditions: (a) The unsaturated carboxylic acid monomer is contained in a proportion of 1 to 80% by weight based on the monomer composition. (B) at least one of the unsaturated carboxylic acid monomers
The type must have a molecular weight of 100 or more per one carboxyl group. 2. In the presence of 0.5 to 90% by weight of polymer particles containing 5% by weight or more of an unsaturated carboxylic acid monomer as a monomer component, 10 to 99.5% by weight of a monomer composition satisfying the following conditions (a) and (b): % Of the polymer particles obtained by subjecting the resulting emulsion to emulsion polymerization and then neutralizing the resulting emulsion with a base to swell the polymer particles. Conditions: (a) The unsaturated carboxylic acid monomer is contained in a proportion of 1 to 80% by weight based on the monomer composition. (B) at least one of the unsaturated carboxylic acid monomers
The type must have a molecular weight of 100 or more per one carboxyl group. 3. Powdery polymer particles obtained by drying the polymer particles according to claim 1 or 2. 4. The first, second or third aspect of the present invention.
Item 1 to 50% by weight of polymer particles and mineral pigment 50
100 parts by weight of a pigment comprising 99 to 99% by weight, and 3 to 3 pigment binders.
A paper coating composition containing 0 part by weight.