JP2000160496A - Complex hollow polymer particle, its production, complex loading material for paper composed of the complex hollow polymer particle and paper containing the internally added loading material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a complex loading material having excellent optical characteristics such as intensity characteristics in internal addition to paper, whiteness and opacity by preparing an aqueous dispersion of complex hollow polymer particle to which a polymer electrolyte is connected and which has a positive zeta potential. SOLUTION: A polymer electrolyte such as an amphoteric polyacrylamide in an amount of >=0.1 pt.wt., preferably 0.5-50 pts.wt., more preferably 1-20 pts.wt. is connected to 100 pts.wt. of a hollow polymer particle composed of a polystyrene-based polymer and/or a poly(meth)acrylate-based polymer to give a complex hollow polymer particle. An aqueous dispersion of the complex hollow polymer particle having a positive zeta potential is prepared to give a complex loading material for paper. The complex loading material for paper is internally added to a pulp slurry to make a paper.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a composite hollow polymer particle, an aqueous dispersion thereof, a method for producing the composite hollow polymer particle, a composite filler for paper comprising the composite hollow polymer particle, and a composite hollow polymer. The present invention relates to an internally added paper containing polymer particles. More specifically, a composite hollow polymer particle obtained by binding a polymer electrolyte to a hollow polymer particle and having a positive zeta potential, an aqueous dispersion thereof, a method for producing the composite hollow polymer particle, and the composite The present invention relates to a composite filler for paper comprising hollow polymer particles and an internally added paper containing the composite hollow polymer particles.

[0002]

2. Description of the Related Art Printing papers such as newspapers, magazines, and books are required to be excellent in various optical characteristics such as strength, smoothness, printability, whiteness, blank paper opacity, and opacity after printing. Required. In recent years, saving or effective use of resources and energy has been called for. From this viewpoint, it is necessary to reduce the thickness of the paper and increase the blending ratio of the waste paper pulp in the pulp. However, there is a problem that the thinning of the paper and the increase in the used paper mixing ratio cause a decrease in optical characteristics such as opacity and whiteness and a decrease in paper strength (particularly tear strength).

[0003] In order to improve the optical properties such as whiteness and opacity of paper, fillers generally used in the papermaking process, ie, talc, kaolin clay, heavy calcium carbonate, light calcium carbonate, carbon dioxide, and the like. It is conceivable to increase the amount of inorganic fillers such as titanium and white carbon and organic fillers such as urea-formaldehyde resin and polystyrene particles. However, increasing the amount of these fillers improves opacity, whiteness, smoothness, printability, etc., but also decreases the tensile strength and surface strength of the paper,
This causes problems such as generation of paper dust during high-speed printing. For this reason, there is a limit in improving these optical characteristics by increasing the amount of filler added.

Further, a method is known in which aqueous emulsions of various polymers having cationic charges obtained by polymerizing monomers in the presence of cationic polyvinyl alcohol are added to pulp slurries (Japanese Patent Application Laid-Open No. Sho 63-163). 235597
JP-A-8-170296, JP-A-8-170296
59701, JP-A-8-269889).
JP-A-62-191598 proposes a combination of a polymer obtained by polymerizing a cationic monomer, a cationic or amphoteric polyacrylamide, and bentonite. These are devised because aqueous emulsions of various polymers having a cationic charge have excellent adsorptivity to pulp and fiber. However, these methods do not sufficiently improve opacity.

Japanese Patent Application Laid-Open No. 61-245399 discloses that a polyacrylamide-based resin-adsorbing filler obtained by adsorbing a polyacrylamide-based resin to a urea-formaldehyde-based polymer association and / or a silica-based particle association is added to pulp. And a method for producing a filler-containing paper. However, in order to obtain desired whiteness and opacity using the urea-formaldehyde-based polymer association in this method, it is necessary to use a large amount of the urea-formaldehyde-based polymer association, and the strength characteristics are reduced. Problem. When the silica-based particle association is used, the effect of improving whiteness and opacity is not sufficient. Therefore, in order to obtain a desired strength, it is necessary to increase the amount of adsorption of the polyacrylamide resin,
As a result, the purpose of reducing the weight of the paper cannot be achieved.

JP-A-8-41798 discloses that a filler having a glass transition temperature of 30 ° C. or less adhered to the surface of a filler and a composite filler for paper having a positive surface potential is used. , Whiteness, opacity and the like can be improved. However, the fillers whose effects have actually been confirmed here are only inorganic pigments such as titanium dioxide and calcium carbonate. Further, in this papermaking method, since the polymer to be attached to the filler has a glass transition temperature of 30 ° C. or lower, white pitch in which this copolymer, fine pulp and filler are coaggregated is generated, Problems occur in the process of collecting and disintegrating waste paper.

[0007] In recent years, as a measure for improving the opacity of printed matter, the inclusion of hollow polymer particles in a paper coating composition has been actively performed. Focusing on this fact, attempts have been made to make paper after adding cationic polymerized hollow polymer particles to a pulp slurry. For example, JP-A-3-74440 discloses cationic hollow polymer particles 1 to 1 obtained by subjecting core / shell type polymer particles having a core swollen by an inert liquid containing a cationic emulsifier to foaming treatment. Filled papers containing 50% by weight and water-dispersible fibers are disclosed. However, this method also has a low yield rate of hollow polymer particles, and does not provide a sufficient effect for improving opacity and paper strength. As described above, a method for simultaneously satisfying optical characteristics such as opacity of paper and strength characteristics is as follows.
Not yet established.

[0008]

DISCLOSURE OF THE INVENTION The present invention solves the above-mentioned conventional problems and improves the paper's optical properties such as whiteness and opacity, as well as the strength properties thereof. The purpose of the present invention is to provide a composite filler. Another object of the present invention is to provide a composite hollow polymer particle used as the composite filler for paper, an aqueous dispersion thereof, and a method for producing the composite hollow polymer particle. Still another object of the present invention is to provide an internal paper containing the composite hollow polymer particles.

[0009]

Means for Solving the Problems As a result of diligent studies to achieve the above object, the present inventors have found that a composite obtained by adsorbing an amphoteric polymer electrolyte on the surface of a hollow polymer particle having a negative zeta potential is obtained. It has been found that the use of a filler can significantly improve not only optical properties such as opacity and whiteness of paper, but also strength properties, and further research based on this finding has led to the completion of the present invention. Was.

Thus, according to the present invention, there is provided a composite hollow polymer particle comprising a hollow polymer particle having a polyelectrolyte bonded thereto and having a positive zeta potential, and the hollow polymer particle having a polymer electrolyte. And a method for producing the composite hollow polymer particles. Further, according to the present invention, there is provided an aqueous dispersion of the composite hollow polymer particles. Further, according to the present invention, there is provided a composite filler for paper comprising the composite hollow polymer particles. Furthermore,
According to the present invention, there is provided an internal paper containing the composite hollow polymer particles.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION The composite hollow polymer particles of the present invention
The polymer electrolyte is bonded to the hollow polymer particles, and the zeta potential is positive. The hollow polymer particles for constituting the composite hollow polymer particles are polymer particles having one or more hollow portions inside the particles. The hollow polymer particles that can be used in the present invention are not particularly limited as long as they are organic hollow polymer particles, and typical examples thereof include particles having a thermoplastic resin as a shell.

Examples of the thermoplastic resin include styrene resins such as polystyrene, poly-α-methylstyrene and poly-β-methylstyrene, polymethyl methacrylate, polyethyl methacrylate, polyisopropyl methacrylate, polybutyl isobutyl methacrylate, and the like. In addition to acrylic resins such as polyacrylonitrile and polymethacrylonitrile, polyvinyl chloride, polytetrafluoroethylene, polyvinyl alcohol, poly-o-vinylbenzyl alcohol, poly-m-vinylbenzyl alcohol, poly-p-vinylbenzyl alcohol , Polyvinyl formal, polyvinyl acetal, polyvinyl propional, polyvinyl butyral, polyvinyl isobutyral, polyvinyl tertiary butyl ether, polyvinyl pyrrolidone, polyvinyl carbazole , Cellulose acetate, cellulose triacetate, polycarbonate and the like. Further, those having a shell made of a copolymer or the like obtained by variously combining the monomers used for each of the above polymers can be used. Further, these resins may be hollow polymer particles forming a shell of a multilayer structure.

The hollow polymer particles having these thermoplastic resins as shells can be prepared by any known method (for example, see JP-A-56-3).
No. 2513, JP-A-61-185505, JP-A-62-127336, JP-A-63-1235
09, JP-A-63-135409, JP-A-64-1704, JP-A-2-173101, JP-A-5-279409, JP-A-6-248
No. 012, Japanese Patent Application Laid-Open No. 10-11018, and the like, and the method is not limited by the manufacturing method.

Among these hollow polymer particles, hollow polymer particles in which a polystyrene-based polymer and / or a poly (meth) acrylate-based polymer form a shell of a multilayer structure have a high porosity. Is preferred.

The hollow polymer particles which can be suitably used in the present invention are prepared by using an acidic group-containing monomer and a monomer copolymerizable therewith, for example, as described in JP-A-64-1704. JP-A-5-279409, JP-A-6-248
No. 012, JP-A-10-11018 and the like.

The porosity (the ratio of internal voids to the total particle volume) of the hollow polymer particles that can be used in the present invention is not particularly limited, but is preferably 10% or more. More preferably, it is 30% or more. If the porosity is too low, the effect of improving whiteness and opacity will be insufficient. It is considered that the higher the porosity, the greater the effect of improving whiteness and opacity. However, in practice, it is difficult to produce hollow polymer particles having a porosity of 90% or more.

The size of the hollow polymer particles is not particularly limited, either.
Is preferably 0.2 μm or more and 20 μm or less.
The following are more preferred. Particularly preferably, 0.3μ
m or more and 5 μm or less. When the particle diameter is less than 0.1 μm, the effect of improving whiteness and opacity is small.

The hollow polymer particles for constituting the composite hollow polymer particles of the present invention may be those having a positive charge or those having a negative charge. It preferably has a charge of -0.9 meq / g. The amount of charge is more preferably -0.02 to -0.1 meq / g. The method for imparting such a charge amount is not particularly limited. For example, an α, β-ethylenically unsaturated acid containing a carboxyl group, a sulfonic acid group, or the like as a monomer for forming the copolymer is used. A method using a system monomer can be shown.

As long as the effects of the present invention are not impaired, a part of the hollow polymer particles used in the present invention are bowl-shaped polymer particles as disclosed in JP-A-10-218950, It can be replaced by porous resin particles or the like as disclosed in Japanese Patent Application Laid-Open No. 5-222108.

In the present invention, the polymer electrolyte to be bonded to the hollow polymer particles needs to contain at least a cationic functional group in the molecule. It may have a group or a nonionic functional group in the molecule. When it also has an anionic functional group, it becomes an amphoteric polymer electrolyte. The charge of these polymer electrolytes is not particularly limited as long as the zeta potential of the composite hollow polymer particles obtained by binding them to the hollow polymer particles is positive. For example,
When combined with a hollow polymer particle having a negative charge of about -0.01 to -0.9 meq / g, usually +0.0
1 to 2.0 meq / g, preferably +0.02 to 1.0
What has electric charge of meq / g may be used.

Molecular weight of the polymer electrolyte used in the present invention (average when two or more kinds are used in combination)
Has a number average molecular weight of 5,000 to 10,000,000, preferably 10,000 to 8,000,000, more preferably 30,000 to 5,000,000. When the number average molecular weight is less than 5,000, the yield of the composite hollow polymer particles is low, and the effect of improving the paper strength is small. On the other hand,
If it exceeds 10 million, the cohesive force becomes too large and the floc becomes too large, so that the operability is lowered and the texture of the obtained internal paper is deteriorated.

The polymer electrolyte used in the present invention is:
Any of a natural polymer or a modified product thereof or a synthetic polymer may be used. Specific examples of the polymer electrolyte of the natural polymer and its modified product include starches, guar gums, celluloses, chitin chitosans, and milk proteins.

The synthetic polymer electrolyte which can be used in the present invention can be easily produced by any known method such as homo- or copolymerization of a monomer having various functional groups or introduction of a functional group into various polymers. be able to.

Examples of cationic vinyl monomers for introducing a cationic functional group, which is an essential component of the polymer electrolyte, include N-methylaminoethyl acrylate and N-methylaminoethyl acrylate.
-Methylaminoethyl methacrylate, Nt-butylaminoethyl acrylate, Nt-butylaminoethyl methacrylate, N, N-dimethylaminoethyl acrylate, N, N-dimethylaminoethyl methacrylate, N, N-diethylaminoethyl acrylate, N,
N-diethylaminoethyl methacrylate, N- (2-
N-alkylaminoalkyl esters of ethylenically unsaturated carboxylic acids such as (hydroxypropyl) acrylate and N- (2-hydroxypropyl) methacrylate;
2-hydroxy-3-methacryloxypropyltrimethylammonium chloride, 2-hydroxy-3-acryloxypropyltrimethylammonium chloride, 2-hydroxy-3-methacryloxypropyltriethylammonium chloride, 2-hydroxy-3
-Acryloxypropyltriethylammonium bromide, 2-hydroxy-3-methacryloxypropyltributylammonium chloride, 2-hydroxy-3-methacryloxypropylmethylethylbutylammonium chloride, 2-hydroxy-3-methacryloxypropyldimethylphenylammonium chloride, Quaternary ammonium salts of ethylenically unsaturated carboxylic acid-N-alkylaminoalkyl esters such as 2-hydroxy-3-methacryloxypropyldimethylcyclohexylammonium chloride;

N-aminoethyl vinyl ether, N-methylaminoethyl vinyl ether, N, N-dimethylaminoethyl vinyl ether, N- (3-allyloxy-
2-hydroxypropyl) dimethylamine, N- (4-
N-aminoalkylalkenyl ethers such as allyloxy-3-hydroxybutyl) diethylamine and their quaternary ammonium salts; 2-methylpyridine,
Vinylpyridine, 2-methyl-5-vinylpyridine,
2,4-divinyl-vinylpyridine, 1-methyl-2-
Heterocyclic nitrogen-containing ethylenically unsaturated monomers such as vinylquinoline and N-vinyl-N'-methylimidazole and quaternary ammonium salts thereof; trimethyl- (3-acrylamido-3-dimethylpropyl) -ammonium chloride; And quaternary ammonium salts of acrylamide or methacrylamide such as 3-acrylamidopropyltrimethylammonium chloride and 3-methacrylamidopropyltrimethylammonium chloride.

Nonionic vinyl monomers which are optional components of the polymer electrolyte include styrene, α-methylstyrene, monochlorostyrene, dichlorostyrene, trichlorostyrene, monomethylstyrene, dimethylstyrene,
And styrene monomers such as trimethylstyrene; α, β-unsaturated carboxylic acids such as acrylic acid or methacrylic acid; α, β-unsaturated carboxylic acids such as acrylic acid or methacrylic acid; and methanol, ethanol, propanol, butanol Esters with ethylene glycol, ethylene glycol, 2-ethylhexyl alcohol, glycidyl alcohol and other alcohols; α, β-unsaturated carboxylic acid amide monomers; α, β-unsaturated nitriles such as acrylonitrile and methacrylonitrile Monomers; vinyl carboxylate monomers such as vinyl acetate and vinyl butyrate; vinyl halide monomers such as vinyl chloride, vinyl bromide and vinylidene chloride; diene monomers such as butadiene, chloroprene and isoprene Olefinic monomers such as ethylene and propylene. Among the above, vinyl carboxylate-based monomers, styrene-based monomers, esters of α, β-unsaturated carboxylic acids, α, β-unsaturated nitrile-based monomers and the like are preferred, and among them, vinyl acetate is preferred. , Acrylate, styrene, acrylonitrile and the like are more preferable.

Examples of the anionic vinyl monomer which is an optional component of the polymer electrolyte include α, β-unsaturated carboxylic acids such as acrylic acid, methacrylic acid and itaconic acid, and salts thereof; Rate, methyl maleate,
Partial esters of unsaturated polycarboxylic acids such as ethyl itaconate and salts thereof; α, β-unsaturated sulfonic acids such as vinyl sulfonic acid, styrene sulfonic acid, acrylamide-2-methylpropane sulfonic acid and salts thereof; And the like. These monomers may be used alone or in a combination of two or more.

As a specific method for synthesizing the amphoteric polymer electrolyte, for example, a nonionic vinyl monomer containing an α, β-unsaturated carboxylic acid amide monomer as one component and an anionic vinyl monomer are used. A method of introducing a cationic functional group by a Mannich reaction after copolymerization, a nonionic vinyl monomer containing an α, β-unsaturated carboxylic acid amide monomer as one component (and an anionic vinyl monomer) A) a method of introducing an anionic functional group and a cationic functional group by a Hoffman reaction after polymerization of
A method of polymerizing a nonionic vinyl monomer such as an unsaturated carboxylic acid amide monomer, a cationic vinyl monomer, and an anionic vinyl monomer (for example, see Japanese Patent Application Laid-Open No. 9-19519).
No. 7 publication).

Examples of α, β-unsaturated carboxylic acid amide monomers include acrylamide, methacrylamide;
N-alkyl (meth) such as -methylacrylamide, N-methylmethacrylamide, N-ethylacrylamide, N-ethylmethacrylamide, Nn-propylacrylamide, Nn-propylmethacrylamide
Acrylamide monomer; N, N-dimethylacrylamide, N, N-dimethylmethacrylamide, N, N-diethylacrylamide, N, N-diethylmethacrylamide, N-methyl-N-ethylacrylamide, N-methyl-N- Ethyl methacrylamide, N-methylaminoethyl acrylamide, N-methylaminoethyl methacrylamide, N, N-dimethylaminoethyl acrylamide, N, N-dimethylaminoethyl methacrylamide,
N, N-dimethylaminopropylacrylamide, N,
N, N-dialkyl (meth) acrylamide monomers such as N-dimethylaminopropyl methacrylamide;
N-alkoxy (meth) acrylamide monomers such as -methylolacrylamide, N-methylolmethacrylamide, N-butoxymethylacrylamide, N-butoxymethylmethacrylamide; and the like.

In the present invention, as the amphoteric synthetic polymer electrolyte, those containing an α, β-unsaturated carboxylic acid amide monomer unit are preferably used. The amount of the body unit is preferably 50% by weight or more, more preferably 70% by weight or more, and particularly preferably 90% or more.

The polymer electrolyte used in the present invention is:
Although not necessarily limiting the invention, water-soluble ones are preferred. In the present invention, two or more polymer electrolytes having different compositions or molecular weights can be used in combination.

In the present invention, the polymer electrolyte is used in an amount of 0.1 part by weight or more, preferably 0.5 part by weight or more and 50 parts by weight or less based on 100 parts by weight of the hollow polymer particles.
More preferably, the amount is 1 part by weight or more and 20 parts by weight or less.

The composite hollow polymer particles of the present invention are obtained by binding a polymer electrolyte to the hollow polymer particles.
It requires that the zeta potential be positive. A preferred range of the zeta potential is +0.01 to 100 mV, more preferably +0.1 to 70 mV, and particularly preferably +1.
５０50 mV. If the potential is negative, the object of the present invention cannot be achieved. In order to set the zeta potential of the composite hollow polymer particles in the above range, the charge amount and the amount of the hollow polymer particles and the polymer electrolyte used for the synthesis may be appropriately adjusted.

The composite hollow polymer particles of the present invention can be prepared by binding a polymer electrolyte to the hollow polymer particles. Here, “bond” means a chemical bond in a narrow sense of a covalent bond, an ionic bond, a metal bond, and a coordination bond, as well as electrostatic attraction, dispersive force, hydrogen bond, charge transfer force, and other intermolecular and intermolecular molecules. This is a concept that includes all of the weak bonds in (for example, "Chemical Dictionary" published by Tokyo Chemical Dojinsha
First edition, p. 403, "Chemical bonding"). Specifically, for example, a method of covalently bonding a polymer electrolyte directly or via a bonding group to a polymer or the like constituting the outer shell of the hollow polymer particles, directly or via a metal ion or the like to the hollow polymer particles A method of ion-adsorbing a polymer electrolyte can be exemplified.

As a method of covalently bonding a polymer electrolyte directly or via a bonding group to a polymer constituting the outer shell of the hollow polymer particles, a method of copolymerizing the hollow polymer particles at the time of forming the outer shell polymer is used. And a method of grafting to the shell polymer after formation. Specific examples of the covalent bond include a functional group (for example, a carboxyl group and an epoxy group) present on the surface of the hollow polymer particle and a functional group (for example, an epoxy group, a hydroxyl group, and an amino group) of the polymer electrolyte. ), A method in which, for example, carbodiimide is bonded to a functional group on the surface of the hollow polymer particles, and a polymer electrolyte is further bonded thereto.
Known functional groups can be used in any combination as the functional groups used for forming these bonds. In such a method of producing composite hollow polymer particles by a covalent bond, a combination of a hollow polymer particle having a cationic or anionic charge or having no charge and a cationic polymer electrolyte or an amphoteric polymer electrolyte is employed. Is done.

When the polymer electrolyte is adsorbed on the hollow polymer particles directly or via a metal ion or the like, a method of producing the polymer electrolyte by adsorbing the polymer electrolyte on the hollow polymer particles having a cationic charge is also possible. However, it is preferable to use (2) a method in which a polymer electrolyte is adsorbed on hollow polymer particles having an anionic charge. In the method (2), as the polymer electrolyte, a cationic polymer electrolyte and an amphoteric polymer electrolyte can be used. In order to adsorb these to the hollow polymer particles, they may be directly adsorbed, but preferably, the polyvalent metal cation is adsorbed to the hollow polymer particles, and then the amphoteric polymer electrolyte is adsorbed thereto. . In this case, the anionic portion of the amphoteric polyelectrolyte is strongly adsorbed on the surface of the hollow polymer particles by interposing a polyvalent metal cation, and the cationic portion of the amphoteric polyelectrolyte has a structure extending from the particle surface. Seems to have. In the method (2), it is preferable that the surface charge of the hollow polymer particles or the surface charge in a state in which metal ions are adsorbed be close to zero. When the surface charge is large and negative, the system tends to aggregate when a polymer electrolyte is added thereto. In addition, when the polymer electrolyte is largely positive, the polymer electrolyte is less likely to be adsorbed on the hollow polymer particles due to repulsion with the cationic portion of the polymer electrolyte. The method of adsorption is not particularly limited, for example, adding an aqueous solution of a polymer electrolyte to an aqueous dispersion of hollow polymer particles, mixing both the hollow polymer particles and the polymer electrolyte in an aqueous medium, and the like. Can be shown. Here, the aqueous medium used for the aqueous dispersion or the aqueous solution may be either water or a mixture of water and an organic solvent miscible with water.

The polyvalent metal cation that can be used in the present invention is
Any divalent or higher polyvalent metal cation may be used. Specific examples of the polyvalent metal include alkaline earth metals such as magnesium and calcium; aluminum; zinc, zirconium, and vanadium. Among them, aluminum is preferable. The method for adsorbing the polyvalent metal cation is not particularly limited, but a salt of the polyvalent metal (for example, a hydrochloride, a sulfate, a nitrate, an acetate and the like can be mentioned), a hydroxide and the like. May be added to and mixed with the aqueous dispersion of the hollow polymer particles.

The aqueous dispersion of the composite hollow polymer particles of the present invention can be obtained by conducting the binding reaction of the polymer electrolyte to the hollow polymer particles in an aqueous medium. Further, the composite hollow polymer particles obtained in the non-aqueous medium can be converted into an aqueous dispersion by a conventionally known method.

The composite hollow polymer particles of the present invention can be separated from the aqueous dispersion of the composite hollow polymer particles of the present invention by a known method such as spray drying.

The composite hollow polymer particles of the present invention are useful as fillers for paper. That is, the composite hollow polymer particles of the present invention were added to pulp dispersed in water to obtain a slurry,
By subsequently making paper, an internally-added paper containing the composite hollow polymer particles can be obtained. In preparing the slurry, the composite hollow polymer particles can be added in the form of an aqueous dispersion.

The pulp that can be used in the present invention is not particularly limited as long as it is a pulp that can be dispersed in water, and specific examples thereof include chemical pulp such as unbleached kraft pulp and bleached kraft pulp; mechanical pulp; semi-chemical pulp. Pulp; synthetic wood pulp, pulp obtained from recovered waste paper;
Non-wood pulp and the like can be mentioned. In the present invention, if desired, together with these pulp, glass fiber,
Inorganic fibers such as rock wool; polyester, nylon,
Synthetic fibers such as polyacrylonitrile; ceramic fibers; straw, cotton litter, and the like can be used in combination.

In the internal paper of the present invention, the content of the composite hollow polymer particles varies depending on the desired paper quality, the properties of the composite hollow polymer particles, and the like, but is usually based on 100 parts by weight (dry weight) of pulp. 0.1 to 100 parts by weight, preferably 0.3 to 50 parts by weight. If the amount is less than 0.1 part by weight, the intended effect of improving whiteness and opacity cannot be obtained, and if it exceeds 100 parts by weight, it is economically disadvantageous.

The slurry comprising pulp and composite hollow polymer particles preferably has a pH of 10 or less,
Especially preferably, it is 9 or less. At a pH higher than 10, the yield tends to decrease. The concentration of the slurry is usually 10% by weight or less, preferably 0.4 to 4% by weight. In the present invention, the order of addition of each component when preparing the pulp slurry is not particularly limited.

The internal paper of the present invention may optionally contain a filler, a paper strength improver, a retention aid, other than pulp and composite hollow polymer particles, as long as the effects of the present invention are not impaired.
Other additives can be contained in desired amounts. The method for adding these various additives is not particularly limited.

Examples of the filler include inorganic fillers such as titanium oxide, silica, zinc oxide, barium sulfate, calcium carbonate, calcium oxide, aluminum silicate, diatomaceous earth, clay, magnesium hydroxide, and talc; hollow polymer particles; Organic fillers such as polymer particles and plastic pigments are exemplified.

Examples of paper strength improvers include starch, oxidized starch, cationized starch, esterified starch, guar gum, modified guar gum, anionic polyacrylamide, cationic polyacrylamide, amphoteric polyacrylamide, polyamide epichlorohydrin, and polyamide epoxy resin. And melamine resins.

Specific examples of the retention aid include aluminum sulfate, alum, sodium aluminate, cationized starch, cationic polyacrylamide, amphoteric polyacrylamide and the like. The amount of the retention aid is not particularly limited, but usually, based on the pulp,
It is at most 3% by weight, preferably at most 2% by weight.

Examples of the internal sizing agent include a solution rosin sizing agent, a strengthened rosin sizing agent, a rosin emulsion sizing agent, an alkyl ketene dimer, and an alkenyl succinic anhydride.

Examples of various additives include surfactants,
Antioxidants, fungicides, preservatives, bactericides, pH adjusters,
Examples include water-soluble organic dyes, water-dispersible coloring pigments, melamine-formaldehyde resins, urea-formalin resins, wax emulsions, flame retardants, plasticizers, and the like.

In the present invention, the papermaking method of the pulp slurry containing the composite hollow polymer particles is not particularly limited, but as an example, the following method can be shown. The pulp is appropriately beaten if desired, then dispersed in a predetermined amount of water, and the composite hollow polymer particles are added thereto and stirred. Next, a desired component such as a retention aid is added and the mixture is further stirred, and then the concentration of the slurry is adjusted to obtain a stock slurry. This is applied to a paper machine and then dried to produce a desired internal paper. After the paper making, it is also possible to carry out a calendaring process, if necessary.

The basis weight of the internally added paper obtained by the present invention is not particularly limited, but is usually 20 to 500 g / m 2.
It is chosen in the range of ² . Also, regarding the thickness of the internal paper,
There are no special restrictions.

The internal paper obtained by the present invention has excellent paper strength, smoothness, printability, whiteness, white paper opacity,
Excellent in various optical characteristics such as opacity after printing.
Further, the amount of paper dust generated during drying in the papermaking process is reduced.

The reason that the above effects can be obtained by the present invention is that, in the pulp slurry in which the composite hollow polymer particles of the present invention are dispersed, the cationic portion of the polymer electrolyte adsorbed on the surface of the hollow polymer particles has a space. The ionic bond is formed between the pulp fiber and the pulp fiber having an anionic property, whereby the yield of the hollow polymer particles is improved, and the non-ionic portion of the polymer electrolyte and the pulp fiber are further dried in the drying step. It is presumed that hydrogen bonds are generated and the pulp fibers are strongly bonded to each other via the polymer electrolyte.

The internally added paper of the present invention may be used as it is, or may be used as a base paper for coating or processing.

[0055]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, but it should not be construed that the present invention is limited thereto. In addition,% or part in a reference example, an example, and a comparative example,
Unless otherwise specified, it is based on weight. Further, the weight of the latex is expressed in terms of solid content unless otherwise specified.
In addition, various measured values in the examples were obtained by the following methods.

(Diameter of hollow polymer particles) The diameters of particles measured for 100 particles by a transmission electron microscope are number averaged.

(Charge Amount of Hollow Polymer Particles or Polymer Electrolyte) "New Experimental Chemistry Course 9 Analytical Chemistry II" (edited by The Chemical Society of Japan,
According to the method described on page 557 of Maruzen Co., Ltd., a certain amount of a 1 / 200N glycol chitosan solution (manufactured by Wako Pure Chemical Industries, Ltd.) and 2-3 drops of toluidine blue indicator (Wako Pure Chemical Industries, Ltd.) were added to the diluted sample. (Manufactured by Kogyo Co., Ltd.), and titrated with a 1/400 N polyvinyl potassium sulfate solution (manufactured by Wako Pure Chemical Industries, Ltd.). The end point is when the blue color of the sample disappears and the sample becomes pink or pale purple. The pH at the end of the titration is defined as the measured pH. The amount of each reagent required for titration differs depending on the molecular weight and the amount of charge of the sample. Therefore, in practice, the dilution concentration and the amount of the reagent are appropriately determined by trial and error. The charge amount of the sample is calculated by the following equation. Electric charge (meq / g) = [0.0025 × (1/400)
N polyvinyl potassium sulfate solution titer (ml))-0.
005 x (1 / 200N glycol chitosan solution added amount (ml))] / sample solid content (g)

(Number average molecular weight of polyacrylamide) High performance liquid chromatography HLC-8
020 (manufactured by Tosoh Corporation) as TSK
gel GMPWXL × 2, TSKguardcolu
mn PWXL, 0.1 M Na as eluent
This was measured using NO ₃ and polyethylene glycol as a standard substance.

(Zeta potential) 0.01 N KCl, pH
5.5 Fully automatic electrokinetic phenomenon analyzer PenKe
m This is a measured value with System 3000 (manufactured by PenKem). Under these measurement conditions, the movement of the (composite) hollow polymer particles by the electric field is detected (the polymer electrolyte is not detected). Thus, for example, if a positive zeta potential is observed, the (composite) hollow polymer particles have a positive charge.

(Tear length) JIS P8113-1976
Is obtained by the following equation. Breaking length (km) = Tensile strength / (width of test piece × basis weight of test piece) × 1000

(Whiteness) JIS P8148-1993
Is measured using a spectral color whiteness meter PF10 (manufactured by Nippon Denshoku Industries Co., Ltd.) according to the method described in (1).
%). The higher the value, the better the whiteness.

(Opacity) JIS P8138-197
According to the method of No. 6, it is measured using a spectral color whiteness meter PF10 (manufactured by Nippon Denshoku Industries Co., Ltd.) (unit:%). The higher the value, the better the opacity.

(Content of Hollow Polymer Particles in Internally Added Paper) Using a hollow polymer particle having a known styrene content, a calibration curve of styrene peak area versus hollow polymer particle weight was obtained by pyrolysis gas chromatography. Create using Next, about 1 g of the internally-added paper containing the composite hollow polymer particles was pulverized into paper with a freezer-pulverizer, and the amount of the hollow polymer particles in the paper powder was measured by pyrolysis gas chromatography. (Unit:% by weight) is calculated.

(Content of Inorganic Filler in Internally Added Paper) JIS
The ash content in the internal paper is measured by the method of P8128-1976, and the content (unit:% by weight) is calculated from this.

(Filler Retention Rate) It is calculated from the ratio of the filler added to the slurry to the filler in the internal paper by the following formula. Yield rate (%) = (filler content in internal paper / filler amount added in slurry) × 100

Reference Example 1 A four-necked flask equipped with a stirrer, a thermometer, a reflux condenser, and a nitrogen gas inlet was charged with 50%
Acrylamide aqueous solution 151.6 parts, powder itaconic acid 0.6 part, 80% acrylic acid 2.4 parts, N, N-dimethylaminoethyl acrylate 30% aqueous solution 44.0 parts,
2.8 parts of powdered sodium methacrylsulfonate and 420 parts of ion-exchanged water are charged, and the pH of the reaction system is adjusted to 3.
After removing oxygen in the system through nitrogen gas, the temperature in the system was adjusted to 60 ° C., 1.5 parts of a 10% ammonium persulfate aqueous solution was added with stirring, and the temperature was raised to 90 ° C. Keep at this temperature for a time, number average molecular weight 50,000, +
An amphoteric polyacrylamide (a) having a charge equivalent of 0.5 meq / g was obtained.

Reference Example 2 In the same manner as in Reference Example 1, 50
% Acrylamide aqueous solution 155.5 parts, powdered itaconic acid 1.3 parts, 80% acrylic acid 0.4 parts, N, N-dimethylaminoethyl acrylate 30% aqueous solution 42.8
Parts, 1.5 parts of powdered sodium methacrylsulfonate and 420 parts of ion-exchanged water, the pH of the reaction system was adjusted to 3.5 with dilute sulfuric acid, and oxygen in the system was removed through nitrogen gas. To 60 ° C., add 1.0 part of a 10% aqueous solution of ammonium persulfate with stirring, raise the temperature to 90 ° C., and maintain at this temperature for 2 hours to obtain a number average molecular weight of 10
An amphoteric polyacrylamide (I) having a charge equivalent of +0.6 meq / g was obtained.

Reference Example 3 In the same manner as in Reference Example 1, 50
% Acrylamide solution 74.0 parts, 80% acrylic acid 2.3 parts, N, N-dimethylaminoethyl acrylate 30% aqueous solution 31.4 parts, powdered sodium methacrylsulfonate 0.5 part, 0.1% methylene bis 0.56 parts of acrylamide and 1490 parts of ion-exchanged water were charged, the pH of the reaction system was adjusted to 3.5 with dilute sulfuric acid, and oxygen in the system was removed through nitrogen gas. While adding 1.5 parts of a 10% aqueous ammonium persulfate solution, the temperature was raised to 80 ° C., the temperature was maintained at this temperature for 4 hours, and amphoteric polyacrylamide having a number average molecular weight of 2,000,000 and a charge equivalent of +0.7 meq / g (c) I got

REFERENCE EXAMPLE 4 Using the same apparatus as in Reference Example 1, 9.5 parts of 90% N-vinylformamide, 118.5 parts of vinyl acetate, 0.25 part of powdered sodium methacrylsulfonate, ion exchange After adding 1470 parts of water and removing oxygen in the system through nitrogen gas, the temperature in the system is reduced to 5%.
The temperature was adjusted to 5 ° C, 2.8 parts of a 10% aqueous solution of 2,2'-azobis- (2-amidinopropane dihydrochloride) was added with stirring, and polymerization was performed at 60 ° C for 12 hours. Then, to remove unreacted monomers, ion-exchanged water 7
10 parts were added and distilled for 1 hour. After cooling, 234 parts of 5% concentrated hydrochloric acid was added, and the mixture was heated to 75 ° C. and hydrolyzed for 3 hours to obtain a cationic vinyl alcohol / vinylamine copolymer having a number average molecular weight of 260,000 and a charge equivalent of +0.8 meq / g. (D) was obtained.

Comparative Example 1 Hollow polymer particles were produced according to Example 7 of JP-A-6-248012. The obtained hollow polymer particles [A] have a particle diameter of 0.7 μm and a porosity of 73%.
Met. The hollow polymer particles [A] have a pH of 5.
The zeta potential at 5 was -52 mV.

(Comparative Example 2) A 2000 ml flask equipped with a condenser and a stirrer was charged with 1000 parts of an emulsion of the hollow polymer particles [A] (solid content: 15%).
Was adjusted to 3.7 and heated to 50 ° C. To this, 45 parts of a 15% aqueous solution of aluminum sulfate 14 to 18 hydrate was added and stirred for 20 minutes to obtain an emulsion of cation-adsorbed hollow polymer particles [B] having aluminum ions adsorbed on the surface. . P of cation-adsorbed hollow polymer particles [B]
The zeta potential at H5.5 was -0.5 mV.

Example 1 An emulsion of the cation-adsorbed hollow polymer particles [B] obtained in the same manner as in Comparative Example 2 was charged with an amphoteric polyacrylamide (A) having a number average molecular weight of 50,000 and a charge of +0.5 meq / g. ) Was gradually added, followed by stirring for about 1 hour to allow the amphoteric polyacrylamide to be adsorbed via aluminum ions.
An emulsion of the composite hollow polymer particles [C] of the present invention was obtained. The zeta potential of the composite hollow polymer particles [C] at pH 5.5 was +12 mV.

Example 2 A 5% aqueous solution of amphoteric polyacrylamide (a) having a number average molecular weight of 100,000 and having a charge of +0.6 meq / g 180 was used as the amphoteric polyacrylamide.
An emulsion of composite hollow polymer particles [D] of the present invention having amphoteric polyacrylamide adsorbed via aluminum ions was obtained in the same manner as in Example 1 except for using parts. The zeta potential of the composite hollow polymer particles [D] at pH 5.5 was +15 mV.

Example 3 An emulsion of hollow polymer particles [C] having amphoteric polyacrylamide adsorbed via aluminum ions obtained in the same manner as in Example 1,
Further, 150 parts of a 0.01% aqueous solution of amphoteric polyacrylamide (c) having a number average molecular weight of 2,000,000 and a charge of +0.7 meq / g is gradually added, and then stirred for about 1 hour, and amphoteric via aluminum ions. An emulsion of the composite hollow polymer particles [E] of the present invention to which polyacrylamide was adsorbed was obtained. P of the composite hollow polymer particles [E]
The zeta potential at H5.5 was +14 mV.

Example 4 The hollow polymer particles obtained according to Example 7 of JP-A-6-248012 were further adjusted to pH 9.5 with sodium hydroxide, and then 33 parts of styrene and 20 parts of glycidyl methacrylate were added. After the temperature was raised to 70 ° C., 12 parts of a 10% aqueous solution of 2,2′-azobis- (2-amidinopropane dihydrochloride) was added, the temperature was maintained at 70 ° C., and after 2 hours, 7 parts of glycidyl methacrylate was additionally added. The mixture was further reacted at 70 ° C. for 8 hours to obtain hollow polymer particles having an epoxy group on the surface. The hollow polymer particles adjusted to pH 8 and solid content 5% 10
00 parts, aqueous solution of cationic vinyl alcohol / vinylamine copolymer adjusted to pH 8 and 5% concentration (d) 3
0 parts, 2000 m with condenser and stirrer
, and reacted at 60 ° C. for 24 hours.
An emulsion of the composite hollow particles [N] of the present invention was obtained. The zeta potential of the composite hollow particles [N] at pH 5.5 was +13 mV.

Comparative Example 3 Aluminum Sulfate 14-18
An emulsion of hollow polymer particles [F] having aluminum ions adsorbed on the surface was obtained in the same manner as in Comparative Example 2 except that the amount of the 15% aqueous solution of the hydrate was changed to 100 parts. The zeta potential of the cation-adsorbed hollow polymer particles [F] at pH 5.5 was +25 mV.

Comparative Example 4 Aluminum Sulfate 14-18
Instead of hydrate, number average molecular weight 2,000,000, + 0.7me
Composite hollow polymer particles [G] having adsorbed amphoteric polyacrylamide on the surface in the same manner as in Comparative Example 2 except that 150 parts of a 0.01% aqueous solution of amphoteric polyacrylamide (c) having a charge of q / g was used. ] Was obtained. The zeta potential of the composite hollow polymer particle [G] at pH 5.5 was -50 mV.

Example 5 Bleached hardwood bleached kraft pulp and softwood bleached kraft pulp, which were individually beaten with a Niagara beater, were mixed at a ratio of 80:20.
Canadian Freeness (CSF JIS P8121
1976) 450 ml of pulp slurry was prepared.
The concentration of this pulp slurry was adjusted to 2.4%. While stirring this pulp slurry, an emulsion of the composite hollow polymer particles [C] of the present invention obtained in Example 1 was added to the pulp slurry in an amount of 5% (in terms of solid content) based on the absolute dry weight of the pulp. The mixture was further stirred for 5 minutes to sufficiently disperse the composite hollow polymer particles. Subsequently, 0.5% (in terms of solid content) of aluminum sulfate was added as a 1% aqueous solution to the absolute dry weight of the pulp,
After further stirring for 2 minutes, the pulp slurry concentration was reduced to 0.02.
%, And the mixture was further stirred for 2 minutes to obtain a stock slurry. This paper stock slurry is transferred to a paper box of a square sheet paper machine which has been pre-watered so that the pulp slurry concentration in the paper box becomes about 0.004%, and
A wet sheet was prepared by making a mesh wire mesh. The wet sheet is dehydrated with a squeezing roll having a linear pressure of 5 to 8 kg / cm, dried for 1 minute with a rotary drum dryer at 95 to 110 ° C., and further passed through a super calender with a linear pressure of 35 to 40 kg / cm. P8121- 19
The humidity was adjusted in an atmosphere of 20 ° C. and a humidity of 65% for 24 hours in accordance with No. 76 to prepare paper having a basis weight of 65 g / m ² . About the obtained internal paper [c], the content rate of the composite hollow polymer particles was measured, and the yield rate was calculated. Further, the grammage, whiteness, opacity of white paper and tear length of the internal paper [c] were measured. Table 1 also shows these results.

(Examples 6 to 7, Comparative Examples 5 to 8) Instead of the composite hollow polymer particles [C], the composite hollow polymer particles [D] (Example 6) and [E] (Example) were used, respectively. 7) and cation-adsorbing hollow polymer particles [B] (Comparative Example 5),
[F] (Comparative Example 6), [G] (Comparative Example 7) and [A]
Except for using (Comparative Example 8), the internal papers [d], [e], [b], [f],
[G] and [a] were obtained. The same evaluation as in Example 5 was performed on these internal papers. Table 1 also shows the results.

Comparative Example 9 An internal paper [h] was prepared in the same manner as in Example 5 except that the composite hollow polymer particles [C] were not used.
I got The same evaluation as in Example 5 was performed for this internal paper. Table 1 also shows the results.

[0081]

[Table 1]

From the results shown in Table 1, the internal additive papers ([b] and [f]) obtained using cation-adsorbed particles (Comparative Examples [B] and [F]) in which aluminum ions are adsorbed on hollow polymer particles. ) Or internal hollow paper [g] obtained using composite hollow polymer particles ([G]) in which amphoteric acrylamide is directly adsorbed on hollow polymer particles, the whiteness, opacity and breaking length are simply hollow weights. There is almost no difference from the internal paper [a] obtained by adding the coalesced particles. On the other hand, the internal papers ([c] to (c)) obtained by using the composite hollow polymer particles of the present invention.
It can be seen that [e]) is superior in all of whiteness, opacity, and breaking length as compared with the internal papers of these comparative examples.

(Example 8) Chemothermo-mechanical pulp (CTMP), deinked pulp (DIP) and unbleached softwood kraft pulp (UNKP) were separately beaten with a Niagara beater, and then CTMP: DIP: UNK.
P = 25: 65: 10 mixed at a ratio of Canadian Freeness (CSF JIS P8121-1976) 2
A 90 ml pulp slurry was prepared. The emulsion of the composite hollow polymer particles [C] of the present invention obtained in Example 1 was added thereto in an amount of 1% (in terms of solid content) based on the absolute dry weight of the pulp.
The mixture was further stirred for 5 minutes to sufficiently disperse the composite hollow polymer particles. Subsequently, 1% (in terms of solid content) of aluminum sulfate relative to the absolute dry weight of the pulp was added as a 1% aqueous solution,
After further stirring for 2 minutes, the pulp slurry concentration was reduced to 0.02.
%, And the mixture was further stirred for 2 minutes to obtain a stock slurry. Example 5 was performed using this stock slurry.
In the same manner as above, an internal paper [i] having a basis weight of 43 g / m ² was prepared. The same evaluation as in Example 5 was performed for this internal paper. Table 2 shows the results.

Example 9 Instead of the composite hollow polymer particles [C], the emulsion of the composite hollow polymer particles [N] of the present invention obtained in Example 4 was used in an amount of 2 to the absolute dry weight of the pulp.
% (In terms of solid content), and an internal paper [n] was prepared in the same manner as in Example 8. The same evaluation as in Example 5 was performed for this internal paper. Table 2 shows the results.

(Comparative Examples 10 to 13) Hollow polymer particles [A] (Comparative Example 1) were used instead of the composite hollow polymer particles [C].
0), titanium dioxide (Taipec R-850, manufactured by Ishihara Sangyo Co., Ltd.) (Comparative Example 11) and white carbon (Zeoseal 1100V, manufactured by Taki Kagaku Co., Ltd.) in the same manner as in Example 8 except for using an internal paper. [J] to [l] were obtained. Further, an internal paper [m] was obtained in the same manner as in Example 8, except that the composite hollow polymer particles [C] were not used. The same evaluation as in Example 5 was performed on these internal papers.
Table 2 shows the results.

[0086]

[Table 2]

From the results in Table 2, it can be seen that the internal paper obtained using the composite hollow polymer particles of the present invention is titanium dioxide (internal paper [k]) or white carbon (internal paper [ 1]) that the opacity and the breaking length are excellent as compared with the case where an inorganic pigment such as l)) is used. Further, it can be seen that although the whiteness is not different from titanium dioxide, it is superior to white carbon.

[0088]

By using the composite hollow polymer particles of the present invention as a filler, the internal paper obtained is excellent in strength and further excellent in optical properties such as whiteness and opacity.

Claims (5)

[Claims] 1. A composite hollow polymer particle comprising a hollow polymer particle and a polymer electrolyte bound thereto, and having a positive zeta potential. 2. An aqueous dispersion of the composite hollow polymer particles according to claim 1. 3. The method for producing composite hollow polymer particles according to claim 1, wherein a polymer electrolyte is bonded to the hollow polymer particles. 4. A composite filler for paper comprising the composite hollow polymer particles of claim 1. 5. An internally added paper containing the composite hollow polymer particles according to claim 1.