JP2002105107A - Method for producing aqueous resin dispersion - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a new industrially simple method for producing an aqueous resin dispersion forming a film excellent in water resistance. SOLUTION: This method for producing the aqueous resin dispersion is characterized by comprising an initial polymerizing step of charging a part of a polymerizable monomer component comprising a polymerizable monomer having an acidic group and other polymerizable monomers copolymerizable therewith together with an aqueous medium and an emulsifying agent and polymerizing >=80 wt.% of the charged polymerizable monomer component and a regular polymerizing step of adding the residual polymerizable monomer component and polymerizing the residual polymerizable monomer component, regulating the total amount of the polymerizable monomer having the acidic group used in the whole polymerizing step to 0.1-3 wt.% based on the total amount of the polymerizable monomer component used in the whole polymerizing step, using 3-30 wt.% of the polymerizable monomer component and using 35-100 wt.% of the polymerizable monomer having the acidic group in the initial polymerizing step.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a novel method for producing an aqueous resin dispersion, and the aqueous resin dispersion obtained by the present invention is particularly useful for building materials, wood, paper, fiber, leather and the like. It is useful to use it as a paint or coating agent for a substrate having low water resistance.

[0002]

2. Description of the Related Art In recent years, paints using an aqueous resin dispersion have been widely used, particularly in the field of civil engineering and construction, because of their advantages such as no pollution and low risk of fire. Conventionally, in order to obtain an aqueous resin dispersion, usually, emulsion polymerization is performed,
In order to ensure polymerization stability, mechanical stability, chemical stability, and storage stability of the particles of the obtained aqueous resin dispersion, a large amount of an emulsifier is used or a polymerizable monomer having an acidic group is used. Methods such as copolymerization have been generally known.
However, hydrophilic components such as an emulsifier and a monomer having an acidic group have a drawback that the water resistance of the coating film, specifically, the water resistance, the water resistance, the water absorption resistance, and the water whitening resistance are reduced. Was.

[0003] Thus, various studies have been made on aqueous resin dispersions in order to improve the water resistance of the coating film. However, they are concerned with the particle morphology and particle composition of the aqueous resin dispersion. is there. Regarding the particle morphology, it has been reported that a core / shell structure and a small particle size are obtained by multistage polymerization. The core / shell structure was expected to improve the water resistance because the film-forming effect by the low Tg polymer and the effect of suppressing the water absorption and swelling by the high Tg polymer were expected. Was not sufficient (JP-A-7-70215). In addition, the composite of a high Tg polymer and a low Tg polymer may not be applicable depending on the application because the stain resistance and the scratch resistance are reduced.

[0004] Smaller particle diameters were expected to improve water resistance by accelerating the fusion of particles, but smaller particle diameters could be achieved by increasing the amount of emulsifiers or polymerizable monomers having acidic groups. Need to be stabilized, and as a result, there is a problem that the effect of improving the water resistance is reduced. Also, if the viscosity increases due to the reduction of the particle size, it becomes difficult to handle as a coating agent, so that it is necessary to reduce the solid content, but this leads to an increase in drying time and a decrease in economic efficiency. Although the reduction of the particle size is specifically realized, the amount of the polymerizable monomer having an emulsifier or an acidic group is large, so that it is not sufficient to obtain hot water whitening resistance in a long-term test.
There is a problem that the solid content is low (Japanese Unexamined Patent Publication No.
237115).

[0005] As regards the particle composition, there have been reports of those focusing on the content of hydrophilic components such as polymerizable monomers having an acidic group and emulsifiers. Among them, there is a specific example that focuses on a polymerizable monomer having an acidic group, and the method proposed there is insufficient to obtain hot water whitening resistance of a clear coating film (Japanese Unexamined Patent Publication No. 279688, JP-A-9
-316389). In general, because the content of the hydrophilic component is reduced, the component that promotes water intrusion is reduced.
An improvement in water resistance is expected. However, simply reducing the hydrophilic component lowers the stability of the particles of the aqueous resin dispersion and leaves a problem that the particle size increases. Skin-drying due to over-drying occurs, causing poor drying and whitening of the coating film.

[0006]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an industrially simple and novel method for producing an aqueous resin dispersion which forms a film or the like having extremely excellent water resistance. .

[0007]

Means for Solving the Problems The present inventor has made intensive studies to solve the above-mentioned problems. As a result, in obtaining an aqueous resin dispersion, although a polymerizable monomer having an acidic group is necessary to prevent the polymer particles from increasing in particle size, the polymerizable monomer has a lower water resistance. In order to solve these problems at once, various emulsion polymerization methods were studied. With this, the total amount of the polymerizable monomer having an acidic group in all the polymerization steps is set to a specific range, and then the emulsion polymerization is divided into the initial polymerization step and the main polymerization step. In the polymerization step, the polymerizable monomer component (including a polymerizable monomer having an acidic group and another polymerizable monomer copolymerizable with the same) is used in a total amount used in all the polymerization steps. Using the proportions in the specific range, the reaction was carried out by batch charging with the aqueous medium and the emulsifier, and the polymerization was almost completed once. Thereafter, in the main polymerization step, the remaining polymerizable monomer components were added and reacted. Further, the amount of the polymerizable monomer having an acidic group used in the initial polymerization step is also shown as a ratio in a specific range with respect to the total amount of the polymerizable monomer having an acidic group used in all the polymerization steps. If an aqueous resin dispersion is obtained by a production method characterized by the steps as described above, it has been found that a coating film or the like formed with the aqueous resin dispersion can be improved to one having extremely excellent water resistance and the like, and the present invention It was completed in this way.

[0008] That is, the method for producing an aqueous resin dispersion according to the present invention is a method for preparing a polymerizable monomer having an acidic group and a polymerizable monomer component containing another polymerizable monomer copolymerizable therewith. A part is charged together with an aqueous medium and an emulsifier,
A method for producing an aqueous resin dispersion, comprising: an initial polymerization step of polymerizing 80% by weight or more of the charged polymerizable monomer component, and a main polymerization step of adding and polymerizing the remaining polymerizable monomer component, The total amount of the polymerizable monomer having an acidic group in the total polymerization step is set to 0.1 to 3% by weight of the total amount of the polymerizable monomer component in the entire polymerization step, and the initial polymerization step is performed. In the above, 3 to 30% by weight of the polymerizable monomer component is used, and 35 to 100% of the polymerizable monomer having an acidic group is used.
% By weight.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The process for producing an aqueous resin dispersion of the present invention is characterized by comprising an initial polymerization step and a subsequent main polymerization step. The initial polymerization step is a step which is started by charging an aqueous medium and an emulsifier and a part of a polymerizable monomer component (the use range ratio will be described later) into a reactor and adding a polymerization initiator. It is preferred that In this initial polymerization step, polymerization may be started after adding a polymerizable monomer component to be used as a pre-emulsion partially emulsified by mechanical stirring in advance, or an aqueous medium, an emulsifier, a polymerizable The polymerization may be started from a simple mixed state of the monomer components, but is not particularly limited.

In the above-mentioned initial polymerization step, it is preferable that 80% by weight or more, more preferably 90% by weight or more of the charged polymerizable monomer component is polymerized, and when the above value is reached, the initial polymerization step is completed. The main polymerization step, after the end of the initial polymerization step, the polymerizable monomer component remaining in the initial polymerization step and the remaining polymerizable monomer component that can be newly added, the polymer obtained in the initial polymerization step Refers to the step of further polymerizing. In the main polymerization step, only the polymerizable monomer component may be added, or the polymerizable monomer component and the like may be added as a pre-emulsion partially emulsified by mechanical stirring in advance. It is not limited to. The addition method is preferably batch addition, divided addition, continuous dropping and the like, and may be appropriately selected as necessary, but is not particularly limited thereto.

The present polymerization step may be performed in one stage, but is not particularly limited, and may be performed in multiple stages. The number of stages in the main polymerization step is preferably one to three in order to simplify the production process, but is not particularly limited. In the multi-stage main polymerization step, the polymerizable monomer component
After polymerizing 0% by weight or more, more preferably 90% by weight or more, it is preferable to add a new polymerizable monomer component. When the main polymerization step is performed in multiple stages, the method of adding the polymerizable monomer in each stage is not particularly limited, and may be the same or partially or entirely different. .

In particular, when importance is placed on the water resistance of the coating film (paint surface), the main polymerization step is preferably performed in multiple stages, and the calculation of the polymerizable monomer component used in the first stage of the main polymerization step is performed. The absolute value of the difference between Tg (° C.) and the calculated Tg (° C.) of the polymerizable monomer component used in the final stage is 30 or more, preferably 5
It is preferably 0 or more, more preferably 70 or more. At this time, the calculated Tg (° C.) of the first stage is the calculated Tg of the final stage.
g (° C.) or the calculated Tg (° C.) of the final stage.
May be higher than the calculated Tg (° C.) of the first stage. In the production method of the present invention, the polymerizable monomer component used when synthesizing the aqueous resin dispersion includes a polymerizable monomer having an acidic group and another polymerizable monomer copolymerizable therewith. It is preferable to include

In the production method of the present invention, the total amount of the polymerizable monomer having an acidic group in the total polymerization step is 0.1% of the total amount of the polymerizable monomer component in the total polymerization step. 1
To 3% by weight, more preferably 0.1 to 3% by weight.
5 to 2.5% by weight, even more preferably 1 to 2% by weight
It is. However, when the total amount of the polymerizable monomer having an acidic group in the whole polymerization step is less than 0.1% by weight of the total amount of the polymerizable monomer component in the whole polymerization step, The stability of the physical properties of the aqueous resin dispersion is lowered, and when the aqueous resin dispersion is used for applications such as paints for heating and drying, poor drying of the paint due to skinning caused by over-drying of the coating film. Is not preferred. On the other hand, when the content exceeds 3% by weight, a coating film formed with the aqueous resin dispersion greatly reduces its water resistance and neutralizes particles in the aqueous resin dispersion. At the time of use, it is not preferable because the viscosity becomes high and handling as a paint or a coating agent becomes difficult.

In the initial polymerization step in the production method of the present invention, the total amount of the polymerizable monomer component used is 3 to 30 of the total amount of the polymerizable monomer component used in all the polymerization steps.
%, More preferably from 5 to 20% by weight.
%, Still more preferably 7 to 15% by weight.
However, when the amount of the polymerizable monomer component used in the initial polymerization step is less than 3% by weight of the total amount used in all the polymerization steps, the particles of the resulting aqueous resin dispersion have a large particle size. It is not preferable because the film formability of a coating film formed using this aqueous resin dispersion is reduced. On the other hand, when the content exceeds 30% by weight, heat generation in the initial polymerization step is increased, which causes a problem in safety of the aqueous resin dispersion at the time of production, which is not preferable.

In the initial polymerization step in the production method of the present invention, the total amount of the polymerizable monomer having an acidic group is determined by the total amount of the polymerizable monomer having an acidic group in all the polymerization steps. It is preferably 35 to 100% by weight, more preferably 45 to 100% by weight, and even more preferably 55 to 100% by weight. However, when the total amount of the polymerizable monomer having an acidic group in the initial polymerization step is less than 35% by weight of the total amount of the polymerizable monomer having an acidic group in the entire polymerization step. Is not preferred in a coating film formed with the obtained aqueous resin dispersion, since the effect of improving the water resistance is reduced.

The type of the polymerizable monomer having an acidic group is not particularly limited, but may be a polymerizable monomer having a carboxyl group, a polymerizable monomer having a sulfone group, and an acidic phosphate ester polymerizable monomer. Monomers and the like can be used, and specifically, the following can be preferably mentioned.
Incidentally, the polymerizable monomer having an acidic group exemplified below,
One type may be used alone, or two or more types may be used in combination. As a polymerizable monomer having a carboxyl group,
Ethylenically unsaturated monocarboxylic acids such as (meth) acrylic acid and crotonic acid; ethylenically unsaturated polycarboxylic acids such as fumaric acid and itaconic acid; ethylenically unsaturated polycarboxylic acids such as monoethyl maleate and monoethyl itaconate A partial ester of an acid can be preferably exemplified, but is not particularly limited.

Preferred examples of the polymerizable monomer having a sulfone group include vinyl sulfonic acid, styrene sulfonic acid, and sulfo (meth) acrylate, but are not particularly limited. Examples of the acidic phosphoric acid ester-based polymerizable monomers include 2- (meth) acryloyloxyethyl acid phosphate, 2- (meth) acryloyloxypropyl acid phosphate, 2- (meth) acryloyloxy-3-chloropropyl acid phosphate, and 2- (meth) acryloyloxy-3-chloropropyl acid phosphate. Preferable examples include-(meth) acryloyloxyethyl phenyl acid phosphate, but are not particularly limited.

Among the polymerizable monomers having an acidic group used in the production method of the present invention, water resistance, in particular, water resistance of a coating film formed from the obtained aqueous resin dispersion is particularly important. In this case, it is preferable to use a polymerizable monomer having a carboxyl group among the above-mentioned polymerizable monomers having an acidic group, and an ethylenically unsaturated monocarboxylic acid such as (meth) acrylic acid. More preferably, an acid is used. Examples of other polymerizable monomers copolymerizable with the polymerizable monomer having an acidic group include, but are not particularly limited to, a (meth) acrylate having an alkyl group having 1 to 18 carbon atoms, Examples thereof include aromatic vinyl monomers, vinyl esters and vinyl ethers, and specific examples are shown below. The other polymerizable monomer copolymerizable with the polymerizable monomer having an acidic group exemplified below may be used alone or in combination of two or more.

Examples of the (meth) acrylate having an alkyl group having 1 to 18 carbon atoms include methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, and (meth) acrylic acid. 2-ethylhexyl, n-octyl (meth) acrylate, t-butyl (meth) acrylate, neopentyl (meth) acrylate,
Preferable examples include cyclohexyl (meth) acrylate, 4-methylcyclohexyl (meth) acrylate, cyclododecyl (meth) acrylate, and isobornyl (meth) acrylate, but are not particularly limited. Preferred examples of the aromatic vinyl monomer include styrene, vinyltoluene, and α-methylstyrene, but are not particularly limited.

Preferred examples of the vinyl ester include vinyl acetate and vinyl propionate.
There is no particular limitation. Preferred examples of the vinyl ether include methyl vinyl ether and ethyl vinyl ether, but are not particularly limited. Other examples of the copolymerizable other polymerizable monomer include, but are not particularly limited to, a polyfunctional polymerizable monomer, a polymerizable monomer having a hydroxyl group, and an epoxy group. A polymerizable monomer having a nitrile group, a polymerizable monomer having an amide group, a polymerizable monomer having an amino group, a polymerizable monomer having a heterocycle,
A polymerizable monomer having a silicon component, a polymerizable monomer having a halogen component, a polymerizable monomer having a light stabilizing ability, a polymerizable monomer having an ultraviolet absorbing ability, and the like can be preferably used. A specific example will be described.

The polyfunctional polymerizable monomer includes (meth)
Esters of acrylic acid with polyhydric alcohols such as ethylene glycol, propylene glycol, 1,3-butylene glycol, diethylene glycol, polyethylene glycol, polypropylene glycol, trimethylolpropane, pentaerythritol and dipentaerythritol; polyfunctional vinyls such as divinylbenzene Monomer;
Allyl (meth) acrylate such as allyl (meth) acrylate can be preferably mentioned, but is not particularly limited. Preferred examples of the polymerizable monomer having a hydroxyl group include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, and monoesters of (meth) acrylic acid with polyethylene glycol and polypropylene glycol. It is possible, but not particularly limited.

Preferred examples of the polymerizable monomer having an epoxy group include glycidyl (meth) acrylate and the like, but are not particularly limited. Preferred examples of the polymerizable monomer having a nitrile group include (meth) acrylonitrile and the like, but are not particularly limited. Examples of the polymerizable monomer having an amide group include N-monomethyl (meth) acrylamide, N-
Monoethyl (meth) acrylamide, N, N-dimethyl (meth) acrylamide, diacetone (meth) acrylamide, N-methylol (meth) acrylamide and the like can be preferably mentioned, but are not particularly limited.

Examples of the polymerizable monomer having an amino group include:
Preferable examples include dimethylaminoethyl (meth) acrylate and aminostyrene, but are not particularly limited. As the polymerizable monomer having a hetero ring, isopropenyl oxazoline, vinylpyrrolidone and the like can be preferably mentioned, but it is not particularly limited. Preferred examples of the polymerizable monomer having a silicon component include silane coupling agents such as vinyltrimethoxysilane, γ- (meth) acryloxypropyltrimethoxysilane, allyltriethoxysilane, and trimethoxysilylallylamine. However, there is no particular limitation.

Examples of the polymerizable monomer having a halogen component include halogenated ethylenes such as vinyl chloride, vinylidene chloride, chlorostyrene, vinyl fluoride, and vinylidene fluoride;
Preference is given to (meth) acrylates having a perhaloalkyl group such as perfluorooctylethyl (meth) acrylate, but there is no particular limitation. As a polymerizable monomer having a light stabilizing ability,
4- (meth) acryloyloxy-2,2,6,6-tetramethylpiperidine, 4- (meth) acryloylamino-2,2,6,6-tetramethylpiperidine, 4-
(Meth) acryloyloxy-1,2,2,6,6-pentamethylpiperidine, 4- (meth) acryloyloxy-1-methoxy-2,2,6,6-tetramethylpiperidine, 4-cyano-4- (Meth) acryloyloxy-2,2,6,6-tetramethylpiperidine, 1- (meth) acryloyl-4- (meth) acryloylamino-
2,2,6,6-tetramethylpiperidine, 4-crotoylamino-2,2,6,6-tetramethylpiperidine, 1-crotoyl-4-crotoyloxy-2,2
Preferred are piperidine-based polymerizable monomers such as 6,6-tetramethylpiperidine, but they are not particularly limited.

Examples of the polymerizable monomer having an ultraviolet absorbing ability include benzophenone-based polymerizable monomers such as 2-hydroxy-4- [3- (meth) acryloyloxy-2-hydroxypropoxy] benzophenone; 2'-hydroxy-5 '-(methacryloyloxymethyl) phenyl] -2H-benzotriazole, 2- [2-hydroxy-5- (methacryloyloxyethyl) phenyl]-
2H-1,2,3-benzotriazole, 2- [2′-
Hydroxy-5 '-(methacryloyloxypropyl)
Phenyl] -2H-benzotriazole, 2- [2′-
Hydroxy-5 '-(methacryloyloxyhexyl)
Phenyl] -2H-benzotriazole, 2- [2′-
Hydroxy-3′-t-butyl-5 ′-(methacryloyloxyethyl) phenyl] -2H-benzotriazole, 2- [2′-hydroxy-5? '-T-butyl-
3 '-(methacryloyloxyethyl) phenyl] -2
H-benzotriazole, 2- [2′-hydroxy-
5 '-(methacryloyloxymethyl) phenyl] -5
-Chloro-2H-benzotriazole, 2- [2'-hydroxy-5 '-(methacryloyloxymethyl) phenyl] -5-methoxy-2H-benzotriazole,
-[2'-hydroxy-5 '-(methacryloyloxymethyl) phenyl] -5-cyano-2H-benzotriazole and 2- [2'-hydroxy-5'-(methacryloyloxymethyl) phenyl] -5-t- Butyl-
Benzotriazole-based polymerizable monomers such as 2H-benzotriazole are preferably exemplified, but are not particularly limited.

Among the other polymerizable monomers used in the production method of the present invention, water resistance, in particular, water resistance of a coating film formed from the obtained aqueous resin dispersion is emphasized. In the case, among the other polymerizable monomers exemplified above, an acrylic acid ester having an alkyl group having 6 or more carbon atoms, a methacrylic acid ester having an alkyl group having 4 or more carbon atoms, and an aromatic vinyl monomer It is preferable to include at least one polymerizable monomer classified into any of the above. In particular, when importance is attached to the weather resistance, specifically, the weather resistance of the composition containing the aqueous resin dispersion, among the other polymerizable monomers exemplified above, t-butyl methacrylate and the like may be used. An esterified product of a tertiary alcohol and (meth) acrylic acid, a polymerizable monomer having a silicon component such as a (meth) acrylic ester having a cycloalkyl group such as cyclohexyl methacrylate, or an alkoxysilyl group,
Any of a polymerizable monomer containing a halogen component such as a fluoroolefin, a polymerizable monomer having a light stabilizing ability such as a piperidine type, and a polymerizable monomer having a UV absorbing ability such as a benzotriazole type or a benzophenone type. It is preferable to include at least one polymerizable monomer classified into the following.

The amount of the emulsifier used in the production method of the present invention is not particularly limited, but when emphasis is particularly placed on the water resistance of a coating film formed with the obtained aqueous resin dispersion, The total amount of the emulsifier used in all the polymerization steps is preferably from 1 to 3.5% by weight based on the total amount of the polymerizable monomer components used in all of the polymerization steps.
More preferably, it is set to 〜3% by weight. However, when the total amount of the emulsifier used in the entire polymerization step is less than 1% by weight, it is not preferable because the stability of the particles of the aqueous resin dispersion decreases and the particle diameter increases. On the other hand, when the total amount of the emulsifier used in all the polymerization steps is 3.5% by weight or more, the water resistance decreases, which is not preferable. Also, the method of adding the emulsifier,
Although not particularly limited, it may be put in a reaction vessel in advance during the initial polymerization step, or may be added as a pre-emulsion in the main polymerization step.

The method for adding the emulsifier is not particularly limited, but it may be charged in a reaction vessel in advance during the initial polymerization step, or may be added as a pre-emulsion in the main polymerization step. The type of the emulsifier is not particularly limited, but preferably includes an anionic emulsifier, a nonionic emulsifier, a cationic emulsifier, an amphoteric emulsifier, a polymer emulsifier, and the like, and specific examples are shown below. The emulsifier may be used alone or in combination of two or more. Also, the emulsifiers used in the initial polymerization step and the main polymerization step are all the same,
All or some may be different.

Examples of the anionic emulsifier include alkyl sulfate salts such as ammonium dodecyl sulfate and sodium dodecyl sulfate; alkyl sulfonate salts such as ammonium dodecyl sulfonate and sodium dodecyl sulfonate; ammonium dodecyl benzene sulfonate and sodium dodecyl Alkyl aryl sulfonate salts such as naphthalene sulfonate; polyoxyethylene alkyl sulfate salts such as Hytenol 18E manufactured by Daiichi Kogyo Seiyaku Co., Ltd .; polyoxyethylenes such as Hytenol N-08 manufactured by Daiichi Kogyo Seiyaku Co., Ltd. Alkylaryl sulfate salts; dialkyl sulfosuccinate salts; arylsulfonic acid formalin condensates; fatty acid salts such as ammonium laurate and sodium stearylate; It may be mentioned properly, but is not particularly limited.

Examples of nonionic emulsifiers include polyoxyethylene alkyl ethers such as NAROACTY N-200 manufactured by Sanyo Chemical Industries; Nonipol 20 manufactured by Sanyo Chemical Industries, Ltd.
A polyoxyethylene alkylaryl ether such as 0;
Polycondensates of polyethylene glycol and polypropylene glycol; sorbitan fatty acid esters; polyoxyethylene sorbitan fatty acid esters; fatty acid monoglycerides; polyamides; condensation products of ethylene oxide and aliphatic amines; is not. As the cationic emulsifier,
Alkyl ammonium salts such as dodecyl ammonium chloride and the like can be preferably mentioned, but are not particularly limited.

Preferred examples of the amphoteric emulsifier include betaine ester type emulsifiers, but are not particularly limited. Examples of the polymer emulsifier include poly (meth) acrylates such as sodium polyacrylate; polyvinyl alcohol; polyvinyl pyrrolidone; polyhydroxyalkyl (meth) acrylates such as polyhydroxyethyl acrylate; And copolymers of two or more types of hydrophilic monomers or copolymers with other polymerizable monomers, but are not particularly limited thereto.

Among them, examples of the emulsifier used in the production method of the present invention include the above examples when importance is placed on water resistance, and more specifically, when importance is placed on the water resistance of a coating film formed with the obtained aqueous resin dispersion. It is preferable to use an emulsifier having a polymerizable group (polymerizable emulsifier). When a polymerizable emulsifier is used, it is preferable to fix and disperse the polymerizable emulsifier in a coating film, because concentration and elution of the emulsifier at an interface or a space between particles can be prevented. Hereinafter, this polymerizable emulsifier will be exemplified. As the anionic emulsifier having a polymerizable group, Japanese emulsifier
Bis (polyoxyethylene polycyclic phenyl ether) methacrylated sulfate such as Antox MS-60 manufactured by Sanyo Kasei Kogyo Co., Ltd .;
Propenyl-alkyl sulfosuccinate salts such as;
(Meth) acrylic acid polyoxyethylene sulfate salts such as Eleminor RS-30 manufactured by Sanyo Chemical Industries;
(Meth) acrylic acid polyoxyethylene phosphonate salt; polyoxyethylene alkylpropenyl phenyl ether sulfate salt such as Aqualon BC-10 manufactured by Daiichi Kogyo Seiyaku Co., Ltd .; Aqualon K manufactured by Daiichi Kogyo Seiyaku Co., Ltd.
Ammonium-α-sulfonato-ω-1- such as H-10
(Allyloxymethyl) alkyloxypolyoxyethylene; Adekaria Soap SE-10 manufactured by Asahi Denka Kogyo Co., Ltd.
Ammonium-α-sulfonato-ω-1- (allyloxymethyl) alkylphenyloxypolyoxyethylene; a sulfate ester having an allyl group such as latemul S-180 manufactured by Kao; It is not something to be done.

Examples of the nonionic emulsifier having a polymerizable group include polyoxyethylene alkylpropenyl phenyl ether such as Aqualon RN-20 manufactured by Daiichi Kogyo Seiyaku Co., Ltd .;
1 such as Adekaria Soap NE-10 manufactured by Asahi Denka Kogyo Co., Ltd.
Preferable examples include-(allyloxymethyl) alkylphenyloxypolyoxyethylene and the like, but are not particularly limited. The amount of the aqueous medium used in the present invention is not particularly limited, and is preferably determined in consideration of the solid content of the finally obtained aqueous resin dispersion. The solid content of the aqueous resin dispersion is not particularly limited, but is preferably 35 to 60% by weight, and more preferably 40 to 60% by weight.
55% by weight.

However, when the solid content of the aqueous resin dispersion is less than 35% by weight, economical efficiency is poor, and when it is 60% by weight or more, handling becomes difficult due to a decrease in stability of the aqueous resin dispersion and an increase in viscosity. Is not preferred. The aqueous medium may be charged in a reaction vessel in advance during the initial polymerization step, or may be charged as a pre-emulsion in the main polymerization step. In addition, the aqueous medium can be preferably added as required for cooling, washing, adjusting the solid content, adjusting the viscosity, and the like. Usually, water is preferably used as the aqueous medium, but if necessary, a hydrophilic solvent such as a lower alcohol such as methanol can be preferably used in combination, but is not particularly limited.

The amount of the polymerization initiator used in the present invention is not particularly limited, but is preferably from 0.05 to 0.05 with respect to the total amount of the polymerizable monomer component used in all the polymerization steps. The content is preferably 1% by weight, more preferably 0.1 to 0.5% by weight. However, when the amount of the polymerization initiator used is less than 0.05% by weight based on the total amount of the polymerizable monomer components used in all the polymerization steps, the polymerization rate becomes slow and unreacted polymerizable It is not preferable because the monomer easily remains. On the other hand, if it exceeds 1% by weight, the water resistance decreases. The method of adding the polymerization initiator is not particularly limited, but it is preferable that batch addition, divided addition, continuous dropping, and the like are appropriately selected as needed.

The type of the polymerization initiator used in the present invention is not particularly limited, but an azo compound such as 2,2-azobis (2-diaminopropane) hydrochloride and a peroxide such as potassium persulfate can be used. Preferable examples include peroxides such as sulfates and hydrogen peroxide. In addition,
The polymerization initiator may be used alone or in combination of two or more. In order to accelerate the decomposition of the polymerization initiator, a reducing agent such as sodium bisulfite or a transition metal salt such as ferrous sulfate may be preferably added. In the present invention, after all polymerization steps have been completed, some or all of the acidic groups of the particles of the obtained aqueous resin dispersion can be neutralized with an alkaline substance, and if necessary, the intermediate group can be neutralized. You may leave it as a sum. Generally, the required pH of the aqueous resin dispersion varies depending on its use, but the pH can be preferably adjusted to 5 to 10 depending on the amount of the neutralizing agent to be added.

The type of the neutralizing agent is not particularly limited either, but includes alkali metals such as sodium hydroxide, hydroxides of alkaline earth metals, alkali metals such as calcium carbonate, and carbonates of alkaline earth metals. And organic amines such as ammonia and monomethylamine. The neutralizer may be used alone or in combination of two or more. In particular, when importance is placed on water resistance, in particular, water resistance of a coating film formed using the obtained aqueous resin dispersion, it is preferable to use a volatile alkaline substance such as ammonia.

In the present invention, the additives are not particularly limited, but known additives such as a pH buffer, a chelating agent, a chain transfer agent, and a film-forming auxiliary are preferably used as necessary. Can be used. The aqueous resin dispersion obtained by the production method of the present invention, if necessary, known additives, for example, a crosslinking agent, a crosslinking accelerator, a film-forming auxiliary,
Pigments, dispersants, wetting agents, antifoaming agents, thickeners, preservatives, antifungal agents, antistatic agents, matting agents, fillers, waxes and nonflammable agents may be preferably compounded and used. However, it is not limited to these.

Particularly, in the present invention, as the other polymerizable monomer copolymerizable with the polymerizable monomer having an acidic group, a polyfunctional polymerizable monomer or a polymerizable monomer having a hydroxyl group may be used. ,
A polymerizable monomer having an epoxy group, a polymerizable monomer having a nitrile group, a polymerizable monomer having an amide group, a polymerizable monomer having an amino group and a polymerizable monomer having a heterocyclic ring, When a polymerizable monomer having a silicon component is used, a crosslinking agent having an isocyanate group, an epoxy group, an alkoxysilyl group, a hydrazino group, an oxazoline group or a crosslinking agent such as an acidic compound, an alkaline compound, and a transition metal salt is used. Although it is not particularly limited, such as an accelerator, the use of these in a blended state may be caused by physical properties such as a film formed with the obtained aqueous resin dispersion (water resistance,
It is also effective and preferable from the viewpoint of weather resistance).

In the present invention, as described above, weather resistance can be preferably imparted, but a light-stable substance or a substance having an ultraviolet absorbing ability is added to the obtained aqueous resin dispersion. Also when added, weather resistance can be preferably imparted. Specifically, although not particularly limited, low-molecular-weight light stabilizers and ultraviolet absorbers having no polymerizable group can be preferably mentioned, and these can be obtained by the production method of the present invention. It is preferable to use a method of adding to the aqueous resin dispersion or adding it together with the polymerizable monomer component during the polymerization step. In addition, although not particularly limited, when a light stabilizer having a polymerizable group and an ultraviolet absorber having a polymerizable group are used, first, a polymer is obtained in a step different from the polymerization step of the present invention. Then, it may be added to the aqueous resin dispersion obtained by the production method of the present invention.

In the present invention, the polymerization temperature, the polymerization time,
The conditions such as the stirring speed and the atmosphere are not particularly limited, but are preferably appropriately selected according to the type and scale of the reactor. Specifically, the polymerization temperature is preferably from 40 to 95 ° C., but is more preferably determined in consideration of the type of the polymerization initiator and the type of the polymerizable monomer to be used. In general, the shorter the polymerization time, the easier it is industrially simpler, but the polymerization time is preferably in the range of 2 to 8 hours in consideration of the polymerization speed and safety. The atmosphere is generally and preferably performed in an atmosphere of an inert gas such as nitrogen in order to increase the efficiency of the polymerization initiator.

The aqueous resin dispersion obtained by the production method of the present invention requires extremely excellent water resistance by thoroughly examining the amount of the polymerizable monomer having an acidic group and the polymerization step to be employed. It can be an important component of a composition such as a coating film. Further, an emulsifier having a polymerizable group, an ethylenically unsaturated carboxylic acid, an acrylate having an alkyl group having 6 or more carbon atoms, a methacrylate having an alkyl group having 4 or more carbon atoms, and an aromatic vinyl monomer are used. When the main polymerization step is performed in multiple stages and the effective Tg (° C.) difference is provided between the first stage and the final stage, it can be said to be more preferable and effective. Further, when the emulsifier used amount, the initiator used amount, the solid content of the aqueous resin dispersion, and the type of the neutralizing agent are appropriately selected, the water resistance can be more preferably increased, and furthermore, during the production process, , Stability of physical properties of the aqueous resin dispersion, economical efficiency that can be practically used, and the like.

The aqueous resin dispersion obtained by the production method of the present invention can be used for protection of structures exposed to the weather and weather, inorganic building materials for ceramics, and low water-resistant base materials such as wood, paper, fiber, and leather. It is preferably used for various applications as a paint or a coating agent for protecting, but is not particularly limited. In the present invention, as another polymerizable monomer copolymerizable with the polymerizable monomer having an acidic group, an esterified product of a tertiary alcohol and (meth) acrylic acid, and a (meth) acryl having a cycloalkyl group At least one of an acid ester, a polymerizable monomer having a silicon component, a polymerizable monomer having a halogen component, a polymerizable monomer having a light stabilizing ability, and a polymerizable monomer having an ultraviolet absorbing ability In the case of using, since a coating film formed with the obtained aqueous resin dispersion exhibits high weather resistance, long-term protection of the substrate exposed to weather, heat, and light and maintenance of a beautiful appearance are required. It is preferably and optimally used for the application. For drying conditions, from room temperature drying to heating drying,
It is not particularly limited and can be preferably selected according to various uses.

When used alone, the aqueous resin dispersion obtained by the production method of the present invention may be preferably used as a binder for paints and coating agents,
As a water resistance improver, it is also preferable to blend with another aqueous resin dispersion or an aqueous resin such as a water-soluble resin, but it is not particularly limited thereto. In particular, it is effective to use in combination with another weather-resistant resin such as an acrylic resin, a urethane-based resin, a silicon-based resin, a fluorine-based resin, or a corrosion-resistant resin such as an epoxy resin or an alkyd resin.

[0045]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, but it should not be construed that the invention is limited thereto. In addition, "wt%" in the following tables represents "wt%". [Calculated Tg] The calculated Tg of the copolymer of the polymerizable monomer component was calculated from the following Fox equation. 1 / Tg = Σ (Wn / Tgn) / 100 Here, Wn represents the weight% of the monomer n, and Tgn represents the Tg (absolute temperature) of the homopolymer composed of the monomer n. After the calculation, Tg (absolute temperature) is converted to Tg (° C.) and handled.

[Measurement of solid content]
The sample was dried in a hot air drier at 60 ° C. for 60 minutes, and the weight of the dried sample was precisely weighed. The ratio of the weight after drying to the weight before drying was defined as a solid content, and was represented by% by weight. [Initial reaction rate] After the initial polymerization step, sampling was performed to determine the solid content. The ratio of the measured solid content to the theoretical solid content calculated from the charged amounts of the raw materials used in the initial polymerization step was defined as the reaction rate, and was shown in terms of% by weight. The initial reaction rate was classified as follows and indicated by ○, Δ, and ×. △ and △ were accepted. ：: 90% by weight or more Δ: 80% by weight or more to less than 90% by weight ×: Less than 80% by weight [Particle size measurement] Particle size measuring apparatus for dynamic light scattering (NIC
OMP Model 370). The particle diameter was indicated by a volume average particle diameter.

[Polymerization Stability] After the completion of the polymerization, the aqueous resin dispersion was filtered through a 100-mesh wire net. The aggregate remaining on the wire net was dried for one day with a hot air dryer at 110 ° C., and the weight after drying was measured. The ratio of the amount of agglomerates after drying to the total amount of polymerizable monomers used in all the polymerization steps was defined as the agglomeration rate, and was shown by weight%. The polymerization stability was evaluated based on the agglomeration rate, and was classified as follows, and indicated by で, Δ, and ×. △ and △ were accepted. ：: Less than 0.02% by weight Δ: 0.02% by weight or more to less than 0.1% by weight X: 0.1% by weight or more [Water resistance whitening test] A 75% aqueous butyl cellosolve solution was added to 100 parts of the aqueous resin dispersion. 3 parts were added to obtain a test sample. Test samples were painted on aluminum plates using a 10 mil applicator. Painted board at 100 ℃
Was dried in a hot air drier for 10 minutes to obtain a test plate. After measuring the L value (L1) of the test plate with a color difference meter, the test plate was immersed in deionized water at room temperature for 7 days. After immersion, the test plate was lifted up, and after gently wiping off the water, the L value (L2) was measured with a color difference meter. The degree of whitening is dL (L2-L1)
And evaluated as, ○, □, Δ, ×. ◎, ○, □, △ were accepted. ：: less than 10 〇: 10 or more to less than 20 □: 20 or more to less than 30 Δ: 30 or more to less than 40 ×: 40 or more [Hot water bleaching test] 100% of aqueous resin dispersion was provided with 75% butyl cellosolve aqueous solution. Three parts were added to prepare a test sample. Test samples were painted on aluminum plates using a 10 mil applicator. 100 painted boards
The sample was dried for 10 minutes in a hot-air dryer at a temperature of 10 ° C. to obtain a test plate. After measuring the L value (L1) of the test plate with a color difference meter, the test plate was
Dipped in deionized water at 0 ° C. for 1 day. Immediately after immersion, pull up the test plate and gently wipe off the moisture.
The value (L2) was measured. The degree of whitening is dL (L2-L
Evaluate in 1) and classify as follows, ◎, ○, □, △,
Indicated by x. ◎, ○, □, △ were accepted. ：: less than 10 〇: 10 or more to less than 20 □: 20 or more to less than 30 -Example 1- 826.9 g of deionized water in a flask equipped with a dropping funnel, a stirrer, a nitrogen inlet tube, a thermometer, and a reflux condenser. , 25% aqueous solution 2 of Aqualon HS-10 (Daiichi Kogyo Seiyaku)
8.8 g, 14.4 g of 25% aqueous solution of Aqualon RN-20 (manufactured by Daiichi Kogyo Seiyaku), 54.9 methyl methacrylate
g, butyl acrylate 29.7 g, acrylic acid 5.4 g
And heated to 75 ° C. with stirring while gently blowing nitrogen gas. After the temperature was raised, 54.0 g of a 5% aqueous solution of potassium persulfate was added to initiate polymerization. At this time, the temperature inside the reaction system was raised to 80 ° C. and maintained for 10 minutes. This was the initial reaction.

After the completion of the initial reaction, a 25% aqueous solution of AQUALON HS-10 was maintained at 80 ° C. while maintaining the inside of the reaction system.
4 g, 6.7 g of a 25% aqueous solution of Aqualon RN-20,
Deionized water g, 536.4 g of methyl methacrylate, 270.0 g of butyl acrylate, 3.6 g of acrylic acid, and a pre-emulsion were uniformly dropped over 180 minutes. After the addition, the dropping funnel was washed with 20 g of deionized water, and the washing solution was added to the flask. Thereafter, the temperature was maintained at the same temperature for 60 minutes to complete the polymerization. Next, the inside of the reaction system was cooled to 50 ° C., and 14.1 g of 25% aqueous ammonia was added.
Stirred for 0 minutes. After stirring, the mixture was cooled to room temperature and filtered through a 100-mesh wire net to obtain a polymer dispersion.

Examples 2 to 9 and Comparative Examples 1 to 3 Except that the types of the polymerizable monomer and the emulsifier and / or the amounts used thereof were as shown in Tables 1, 2, 3 and 4, As in Example 1, the main polymerization step was performed by a one-stage polymerization method,
Aqueous aqueous dispersions having different compositions were obtained. Evaluation result is Example 1.
The results are shown in Tables 1, 2, 3 and 4. The amount of each polymerizable monomer used in the table is a percentage of the total amount of the polymerizable monomer component used in all the polymerization steps, and is shown in% by weight. The amount of each emulsifier used was expressed as a percentage by weight relative to the total amount of the polymerizable monomer component used in all the polymerization steps.

Each polymerizable monomer is represented by the following abbreviations. MMA: methyl methacrylate CHMA: cyclohexyl methacrylate BA: butyl acrylate 2EHA: 2-ethylhexyl acrylate St: styrene AA: acrylic acid (*) MAA: methacrylic acid (*) (*) Polymerizable monomer having an acidic group body

[0051]

[Table 1]

[0052]

[Table 2]

[0053]

[Table 3]

[0054]

[Table 4]

Example 10 826.9 g of deionized water and 25% of Aqualon HS-10 (Daiichi Kogyo Seiyaku) were placed in a flask equipped with a dropping funnel, a stirrer, a nitrogen inlet tube, a thermometer and a reflux condenser. Aqueous solution 2
8.8 g, 14.4 g of a 25% aqueous solution of RN-20 (Daiichi Kogyo Seiyaku), 9.0 g of styrene, 62.1 g of methyl methacrylate, 13.5 g of 2-ethylhexyl acrylate
g and acrylic acid 5.4 g, and the temperature was raised to 75 ° C. with stirring while gently blowing nitrogen gas. After heating, 54.0 g of a 5% aqueous potassium persulfate solution was added,
The polymerization was started. At this time, the temperature inside the reaction system was raised to 80 ° C. and maintained for 10 minutes. This was the initial reaction.

After completion of the initial reaction, a 25% aqueous solution of AQUALON HS-10 was maintained at 80 ° C.
4 g, 6.7 g of a 25% aqueous solution of RN-20, 99.8 g of deionized water, 36.0 g of styrene, 264.6 g of methyl methacrylate, 55.8 of 2-ethylhexyl acrylate
g and 3.6 g of acrylic acid were dropped uniformly over 80 minutes. After the addition, the dropping funnel was washed with 20 g of deionized water, and the washing solution was added to the flask. Thereafter, the temperature was maintained at the same temperature for 30 minutes to complete the first-stage polymerization. Next, while maintaining the inside of the reaction system at 80 ° C., 5.8 g of a 25% aqueous solution of Aqualon HS-10,
2.9 g of a 25% aqueous solution of Aqualon RN-20, 139.2 g of deionized water, 45.0 g of styrene, 172.8 g of methyl methacrylate, 2-ethylhexyl acrylate 2
100 g of the second stage pre-emulsion consisting of 32.2 g
The solution was dropped uniformly over a period of minutes. After dripping, deionized water 20
g, the dropping funnel was washed, and the washing liquid was added to the flask. Thereafter, the temperature was maintained at the same temperature for 60 minutes to complete the second-stage polymerization.

Next, the inside of the reaction system was cooled to 50 ° C.
% Ammonia water and stirred at the same temperature for 10 minutes. After stirring, the mixture was cooled to room temperature and filtered through a 100-mesh wire net to obtain a polymer dispersion. -Examples 11 to 15 and Comparative Examples 4 and 5-Example 10 except that the types of the polymerizable monomer and the emulsifier and / or the amount of the emulsifier were changed as shown in Table 5, Table 6, Table 7 and Table 8. Similarly to the above, the main polymerization step was carried out by a two-stage polymerization method to obtain aqueous aqueous dispersions having different compositions. The evaluation results are shown in Table 5, Table 6, Table 7, and Table 8 together with Example 10.

The amount of each polymerizable monomer used in the table is a percentage of the total amount of the polymerizable monomer components used in all the polymerization steps, and is shown by weight%. The amount of each emulsifier used is a ratio to the total amount of the polymerizable monomer component used in all the polymerization steps,
Indicated by weight%. Each polymerizable monomer is represented by the same abbreviation as described above.

[0059]

[Table 5]

[0060]

[Table 6]

[0061]

[Table 7]

[0062]

[Table 8]

[0063]

According to the present invention, it is possible to provide a novel method for producing an aqueous resin dispersion which forms a film and the like having extremely excellent water resistance.
Protection of structures exposed to the weather, inorganic building materials for ceramics, wood,
It can be widely used as a paint, a coating agent, and the like for protecting a low water-resistant substrate such as paper, fiber, and leather.

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Akio Ito 5-8 Nishiburi-cho, Suita-shi, Osaka Nippon Shokubai Co., Ltd. F-term (reference) 4J011 KA02 KA04 KA05 KA06 KA08 KA09 KA14 KA15 KA16 KB09 KB13 KB14 KB29 4J100 AB02P AB03P AB04P AB07Q AE03P AE04P AG04P AJ01Q AJ02Q AJ08Q AJ09Q AL03P AL04P AL05P AL08P AL08Q AP01Q BA56Q BA65Q BC02P BC04P CA04 FA34

Claims (4)

[Claims] 1. A part of a polymerizable monomer component containing a polymerizable monomer having an acidic group and another polymerizable monomer copolymerizable therewith is charged together with an aqueous medium and an emulsifier. A method for producing an aqueous resin dispersion, comprising: an initial polymerization step of polymerizing 80% by weight or more of the polymerizable monomer component, and a main polymerization step of adding and polymerizing the remaining polymerizable monomer component. The total use amount of the polymerizable monomer having a group in all the polymerization steps is set to 0.1 to 3% by weight of the total use amount of the polymerizable monomer component in all the polymerization steps. Is 3 to 30 of the polymerizable monomer component.
% Of the polymerizable monomer having an acidic group by weight.
A method for producing an aqueous resin dispersion, comprising using 5 to 100% by weight. 2. The method for producing an aqueous resin dispersion according to claim 1, wherein the emulsifier is an emulsifier having a polymerizable group. 3. An acrylic acid ester having an alkyl group having 6 or more carbon atoms, wherein the other polymerizable monomer is
The method for producing an aqueous resin dispersion according to claim 1, wherein the aqueous resin dispersion comprises at least one polymerizable monomer classified into any of the above-mentioned methacrylate having an alkyl group and an aromatic vinyl monomer. . 4. The method according to claim 1, wherein the main polymerization step comprises multiple stages, and the calculated Tg of the polymerizable monomer component used in the first stage of the main polymerization step is calculated.
(° C) and calculation T of the polymerizable monomer component used in the final stage
The method for producing an aqueous resin dispersion according to any one of claims 1 to 3, wherein the absolute value of the difference from g (° C) is 30 or more.