JP2000044639A - Production of aqueous resin emulsion - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce an aqueous resin emulsion capable of forming a film excellent in water and fouling resistances, etc., and suitable as a coating material or an adhesive, etc. SOLUTION: This method for producing an aqueous resin emulsion comprises copolymerizing a macromonomer which is a copolymer prepared by copolymerizing (a) a macromonomer having a radical-polymerizable group at one terminal of a silicone or a hydrophobic vinyl polymer with (b) a polyalkylene glycol (mono)methacrylate or a polyalkylene glycol monomalkyl ether mono(meth)acrylate and, as desired, (c) other radical-polymerizable monomers and having the macromonomer unit (a) in an amount of 40-1 wt.% based on the total amount of all the constituent units, the monomer unit (b) in an amount of 60-99 wt.% based on the total amount of all the constituent units and the monomer unit (c) in an amount of 0-15 wt.% based on the total amount of all the constituent units and further having the radical-polymerizable group at one terminal of the copolymer with other radical-polymerizable monomers in the presence or absence of an emulsifying agent in an aqueous medium.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing an aqueous resin emulsion, and a film formed from the aqueous resin emulsion obtained by the present invention is excellent in water resistance, stain resistance, etc. The emulsion is suitably used as an aqueous type paint and adhesive.

[0002]

2. Description of the Related Art Water-based resin emulsions are made of paints, adhesives, paper processing agents, fiber processing agents, mortar modification, taking advantage of their pollution-free properties, good workability, and resource saving. It is used for a wide range of applications such as agents. Conventionally,
Aqueous resin emulsions are most commonly produced by emulsion polymerization of monomers using low molecular weight compounds such as sodium alkyl benzene sulfonate, polyoxyethylene alkyl allyl ether sulfate or polyoxyethylene nonyl phenyl ether as emulsifiers. It had been. However, the aqueous resin emulsion produced by the above method has a problem that the water resistance of a dried and formed film is inferior due to a low molecular weight emulsifier.

As a method for solving the above problems, there is a method in which a monomer is emulsion-polymerized in the presence of a polymer emulsifier, or a method having a radically polymerizable unsaturated group and being incorporated into a part of the polymer during polymerization. There is an emulsion polymerization method using a reactive emulsifier (for example, JP-A-5-154369 and JP-A-9-3144). However,
The water resistance of the film formed from the resin emulsion obtained by the above method was just one step away. Examples of reactive emulsifiers include polyethylene glycol mono (meth)
Acrylate was also known, but it was inferior in copolymerizability with other monomers used as a main component of the emulsion polymerization and easily remained unreacted, so that the water resistance of the obtained resin emulsion was After all it was not enough.

[0004]

Means for Solving the Problems The present inventors have conducted intensive studies to solve the above problems, and as a result, by using a radical polymerizable macromonomer having a specific structure,
Even without the use of conventionally used emulsifiers, or even with the use amount thereof being considerably reduced, it has been found that monomers can be emulsion-polymerized stably in an aqueous medium, and according to the emulsion polymerization, They have found that an aqueous resin emulsion that forms a film having excellent water resistance can be obtained, and have completed the present invention. That is, the present invention is a method for producing an aqueous resin emulsion, comprising copolymerizing the following macromonomer and other radically polymerizable monomers in an aqueous medium in the presence or absence of an emulsifier. Macromonomer: (a) a macromonomer having a radical polymerizable group at one end of silicone or a hydrophobic vinyl polymer, (b) polyalkylene glycol mono (meth) acrylate or polyalkylene glycol monoalkyl ether mono (meth) acrylate; If desired, a copolymer obtained by copolymerizing (c) other radically polymerizable monomers, wherein the ratio of the (a) macromonomer unit is 40 to 40% based on the total amount of all structural units. 1% by weight, and the proportion of the monomer unit (b) is 60 to 99% by weight.
And (c) a macromonomer having a specific configuration as described above, wherein the macromonomer having a radical polymerizable group at one end of a copolymer having a monomer unit ratio of 0 to 15% by weight is defined as the macromolecule of the present invention. It is called a monomer. Hereinafter, the present invention will be described in more detail.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION The macromonomer of the present invention can be synthesized by a method employed for producing a conventionally known radically polymerizable macromonomer. That is, by radical polymerization using a mercapto compound having a carboxyl group such as mercaptopropionic acid as a chain transfer agent, (a)
Macromonomer having a radical polymerizable group at one end of silicone or hydrophobic vinyl polymer, (b) polyalkylene glycol mono (meth) acrylate or polyalkylene glycol monoalkyl ether mono (meth)
A copolymer having a carboxyl group derived from the mercapto compound at one end of a molecular chain (hereinafter, sometimes referred to as a base polymer) by copolymerizing acrylate and (c) other radically polymerizable monomers as desired. )
Get. Then, by reacting the copolymer with glycidyl methacrylate or the like, a macromonomer of the present invention having a methacryloyl group as a radical polymerizable group at one end can be obtained.

The above-mentioned (a) in the macromonomer of the present invention
As described above, the proportion of the macromonomer unit, the proportion of the (b) monomer unit, and the proportion of the (c) monomer unit are, as described above, based on the total amount of (a) macromonomer unit;
0 to 1% by weight, (b) a monomer unit; 60 to 99% by weight, and (c) a monomer unit; 0 to 15% by weight. (A) If the proportion of the macromonomer unit is out of the range of 40 to 1% by weight, the balance between the hydrophobic component and the hydrophilic component is lost, and the surface activity of the obtained macromonomer is impaired. The preferred number average molecular weight of the macromonomer of the present invention is from 1,000 to 20,000. If the number average molecular weight of the macromonomer is less than 1,000, the property of repelling oil ink or the like is likely to be insufficient, while if it exceeds 20,000, unreacted macromonomer remains in the aqueous resin emulsion, and When the macromonomer flows out of the formed film by rainwater or the like, the stain resistance of the film is easily reduced.

The component (a) in the present invention is a macromonomer having a radical polymerizable group at one terminal of silicone or a hydrophobic vinyl polymer, that is, a silicone macromonomer or a hydrophobic vinyl polymer macromonomer. Examples of the silicone macromonomer include a radical polymerizable group such as a (meth) acryloyl group at one end of a molecule of a polyorganosiloxane represented by polydimethylsiloxane, polydiethylsiloxane, polymethylphenylsiloxane, and polydiphenylsiloxane. Bound macromonomers are included. Commercially available silicone macromonomers such as AK-5, AK-30, AK-32 manufactured by Toagosei Co., Ltd. and X-22-174DX manufactured by Shin-Etsu Chemical Co., Ltd. can also be used. The preferred number average molecular weight of the silicone macromonomer is from 500 to 10,000. The number average molecular weight of the silicone macromonomer is 50
If it is less than 0, the stain resistance of the coating film tends to be insufficient, while 1
If it exceeds 000, it is difficult to obtain a transparent multi-branched polymer solution.

Examples of the hydrophobic vinyl polymer-based macromonomer include macromonomers having a radical polymerizable group at one end of a hydrophobic vinyl polymer such as polymethyl methacrylate or polybutyl methacrylate. Examples of the hydrophobic vinyl polymer serving as the skeleton of such a macromonomer include homopolymers or copolymers of alkyl (meth) acrylate, styrene, acrylonitrile, perfluoroalkylethyl (meth) acrylate, and hydroxyalkyl (meth) acrylate. And the number average molecular weight is 1,
000 to 10,000 are preferred. As the radical polymerizable group, a (meth) acryloyl group, a styryl group and the like are preferable.

The component (b) is a polyalkylene glycol mono (meth) acrylate or a polyalkylene glycol monoalkyl ether mono (meth) acrylate (hereinafter sometimes referred to as a polyalkylene glycol monomer). Preferred polyalkylene glycol mono (meth) acrylates include polyethylene glycol mono (meth) acrylate and polypropylene glycol mono (meth) acrylate. Examples of the polyalkylene glycol monoalkyl ether mono (meth) acrylate) acrylate include methoxypolyethylene glycol mono (meth) acrylate, ethoxypolyethylene glycol mono (meth) acrylate, butoxypolypropylene glycol mono (meth) acrylate, and methoxypolyethylene glycol polypropylene glycol. Mono (meth) acrylate and the like can be mentioned. In addition to the above compounds, methoxypolytetramethylene glycol polyethylene glycol mono (meth) acrylate and benzyloxy polyethylene glycol (meth) acrylate can also be used.

The preferred degree of condensation of the alkylene oxide repeating unit in the polyalkylene glycol monomer is 2 to 50, more preferably 3 to 30. When the condensation degree of the alkylene oxide repeating unit is 50
If it exceeds 300, the water resistance of the film formed from the obtained hyperbranched polymer tends to decrease. The preferred number of carbon atoms of the alkylene in the alkylene oxide unit forming the polyalkylene glycol-based monomer is 2 or 3, and particularly preferably 2.

In order to form a base polymer in the macromonomer of the present invention, in addition to the above components (a) and (b), other radical polymerizable monomers such as alkyl (meth) acrylate, vinyl carboxylate, (Meth) acrylonitrile, styrene and perfluoroalkylethyl (meth) acrylate and perfluoroalkyl (meth) acrylate may be used. The amount of the other radical polymerizable monomer to be used is 0 to 15% by weight based on the total amount of all the constituent units in the base polymer.

As described above, the base polymer of the macromonomer of the present invention is produced by radically polymerizing the above components (a) to (c) in the presence of a mercapto compound having a carboxyl group. Examples of the mercapto compound used as a chain transfer agent include mercaptoacetic acid, mercaptopropionic acid, mercaptobutyric acid, and thiomalic acid. The preferred amount of the mercapto compound used is an amount equimolar to the obtained base polymer, and specifically, base polymer: mercaptorcarboxylic acid = 1: 1
(0.8 to 1.3) (molar ratio).

The polymerization temperature is preferably from 50 to 140 ° C., and the polymerization solvent is ethyl acetate, butyl acetate,
Methyl isobutyl ketone, toluene or xylene can be preferably used. As the polymerization initiator, azobisisobutyronitrile, azobisdimethylvaleronitrile,
Examples thereof include azobiscyclohexanecarbonitrile, benzoyl peroxide, toluoyl peroxide, butyl peroxypivalate, and butyl peroxyoctanoate. The preferred amount is 0.1 to 3 per 100 parts by weight of the monomer. Parts by weight.

A base polymer obtained by the above method,
The macromonomer of the present invention can be obtained by reacting a functional group having reactivity with the carboxyl group, for example, a monomer having an epoxy group. As the monomer having an epoxy group (hereinafter referred to as an epoxy group-containing monomer),
Glycidyl (meth) acrylate or 3,4-epoxycyclohexylmethyl methacrylate is exemplified. The base polymer and the epoxy group-containing monomer can be reacted by heating both to 50 to 140 ° C. in the presence of a catalyst in an organic solvent such as a base polymer solution obtained by solution polymerization. The amount of the epoxy group-containing monomer used is equal to or more than the carboxyl group bonded to one end of the base polymer, specifically, 1.0 to 1.5 times the carboxyl group. Molar is preferred.

In order to accelerate the addition reaction between the carboxyl group and the epoxy group of the base polymer, tertiary amines such as triethylamine and tripropylamine, and tetraethylammonium bromide, tetrabutylammonium bromide, triethylbenzylammonium chloride and the like can be used.
It is preferable to add an appropriate amount of a quaternary phosphonium salt such as a quaternary ammonium salt or a tetraphosphonium salt as a catalyst.

In the present invention, the macromonomer of the present invention and other radically polymerizable monomers are copolymerized in an aqueous medium in the presence or absence of an emulsifier. The monomer to be copolymerized with the macromonomer naturally depends on the intended use of the obtained aqueous resin emulsion. For example, (meth) acrylate, vinyl carboxylate, (meth) acrylonitrile, styrene, perfluoroalkyl ( (Meth) acrylate, dimethylaminoethyl (meth) acrylate, N-alkyl (meth) acrylamide, (meth) acrylic acid, maleic acid, itaconic acid, maleic anhydride, styrenesulfonic acid, 2-acrylamido-2-methylpropanesulfonic acid , Acid phosphoxyethyl methacrylate and 3-chloro-2
Acid phosphoxypropyl methacrylate; Further, alkali metal salts, ammonium salts and amine salts of monomers having an acidic group such as a carboxyl group, a sulfo group or a phospho group can be used in combination with the unsaturated monomer. Preferred copolymerization ratios of the macromonomer and the copolymerizable monomer are 1 to 30% by weight of the macromonomer and 99 to 70% by weight of the copolymerizable monomer based on the total amount thereof.

In order to obtain an aqueous resin emulsion suitable as an adhesive, a monomer mixture comprising, for example, butyl acrylate, methyl methacrylate, and acid phosphoxyethyl methacrylate as the copolymerized monomer of the macromonomer of the present invention. No. In order to obtain a preferred aqueous resin emulsion for the pressure-sensitive adhesive, 2-ethylhexyl acrylate as a comonomer of the macromonomer,
A monomer mixture composed of acrylonitrile and itaconic acid, etc. may be mentioned.In order to obtain an aqueous resin emulsion suitable for a paint or a coating agent, styrene, butyl methacrylate, methyl methacrylate and methacrylic acid are used as such copolymerizable monomers. And the like.

When the above components are copolymerized in an aqueous medium, a nonionic emulsifier, an anionic emulsifier or a nonionic anionic emulsifier may be used. And sorbitan polyethylene oxide and polyethylene oxide propylene oxide. Examples of the anionic emulsifier include alkali metal salts of sulfosuccinic acid, alkali metal salts of alkylbenzenesulfonic acid and alkali metal salts of alkylnaphthalenesulfonic acid.
Examples of the nonionic anionic emulsifier include sodium polyoxyethylene lauryl ether sulfate and sodium polyoxyethylene octyl phenyl ether sulfate. The preferred amount of the emulsifier used is
It is 0.3 to 3% by weight based on the total amount of the macromonomer of the present invention and the comonomer. In the present invention,
Since a macromonomer having surface activity is used as a polymerization component, the amount of the emulsifier used in combination differs depending on the amount of the macromonomer used, but the amount of the emulsifier used can be considerably reduced as compared with the case of ordinary emulsion polymerization.

Examples of the polymerization initiator include potassium persulfate, ammonium persulfate, hydrogen peroxide, cumene hydroperoxide, butylcumyl peroxide, benzoyl peroxide, toluoyl peroxide, and azobisisobutyronitrile. Further, in order to adjust the molecular weight of the obtained polymer, mercaptoethanol, 2
-A chain transfer agent such as propanethiol, 1-butanethiol, thiophenol or dodecylmercaptan may be used. Applications of the aqueous resin emulsion obtained by the above method include paints, coating agents, adhesives, pressure-sensitive adhesives, impregnating reinforcing agents, and the like. As a base material on which this is applied, there are metal, paper, wood, glass, concrete and the like.

Hereinafter, the present invention will be described more specifically with reference to Examples and Comparative Examples. Note that “parts” in each example means “parts by weight”. Production Example 1 A mixture of 100 parts of toluene and 1.8 parts of 3-mercaptopropionic acid was heated to 90 ° C. under a nitrogen stream and stirred, and methoxypolyethylene glycol monomethacrylate (average degree of polymerization of ethylene oxide) was added to the liquid. 9) 8
0 parts, 20 parts of polydimethylsiloxane-terminated methacryloyl-type macromonomer (X-22-174DX; number average molecular weight: about 5,000, manufactured by Shin-Etsu Chemical Co., Ltd.) and 1 part of azobisisobutyronitrile are dropped over 4 hours. did. By further heating for 2 hours, a toluene solution of a base polymer having a carboxyl group at one terminal and having a number average molecular weight of 7,300 was obtained. A solution prepared by dissolving 2.65 parts of glycidyl methacrylate, 0.9 part of tetrabutylammonium bromide and 0.05 part of hydroquinone monomethyl ether in 10 parts of toluene was added dropwise to the above toluene solution. Allowed to react for hours. After that, remove the solvent with a spray dryer,
The macromonomer (1) of the present invention was obtained. Its number average molecular weight was 7,500 and weight average molecular weight was 17,100.

Production Example 2 In place of the polymethysiloxane-terminated methacryloyl-type macromonomer in Production Example 1, polymethyl methacrylate-terminated methacryloyl-type macromonomer (AA-
6, a toluene solution of a base polymer having a number average molecular weight of 7,500 and having a carboxyl group at one end, in the same manner as in Production Example 1, except that a number average molecular weight of about 6,000, manufactured by Toagosei Co., Ltd. was used. I got Hereinafter, the macromonomer (2) of the present invention was obtained in the same manner as in Production Example 1. Its number average molecular weight is 7,700 and weight average molecular weight is 17,600.
Met.

[0022]

EXAMPLE 1 20 parts of the macromonomer (1) of the present invention, 20 parts of butyl methacrylate, 30 parts of styrene, 20 parts of ethyl acrylate, 1 part of methacrylic acid, 9 parts of hydroxyethyl methacrylate and 30 parts of ion-exchanged water were mixed by a homomixer. The pre-emulsion was adjusted. In a glass flask equipped with a stirrer, a dropping funnel, a nitrogen gas inlet tube and a thermometer, put 70 parts of ion-exchanged water, 0.4 parts of potassium persulfate and 0.7 parts of ammonium carbonate, and replace the gas phase with nitrogen. After that, the solution was kept at 80 ° C., and the pre-emulsion was added dropwise over 2 hours. After the addition, the temperature was maintained at 80 ° C. for another hour to complete the polymerization. Thereafter, the mixture was neutralized with triethylamine until the pH became 8, thereby obtaining an intended aqueous resin emulsion. The following physical properties were measured for the obtained resin emulsion. As a result, both the results of the storage stability test and the water resistance test were good, and the grid amount was as small as 0.05 part. a) Storage stability test: After the emulsion was stored at 25 ° C for one week, the appearance was visually evaluated. b) Water resistance test of coating film; applying emulsion to steel sheet,
After drying at 25 ° C. for 2 weeks, the test piece was immersed in water for 2 days, and the whitening state was visually observed. c) Grid; Filtration through a 200 mesh net, drying of aggregates on the net and weighing.

[0023]

Example 2 20 parts of the macromonomer (2) of the present invention, 20 parts of butyl methacrylate, 30 parts of styrene, 20 parts of ethyl acrylate, 1 part of methacrylic acid, 9 parts of hydroxyethyl methacrylate and 30 parts of ion-exchanged water were mixed with a homomixer. The pre-emulsion was adjusted. In a glass flask equipped with a stirrer, a dropping funnel, a nitrogen gas inlet tube and a thermometer, put 70 parts of ion-exchanged water, 0.4 parts of potassium persulfate and 0.7 parts of ammonium carbonate, and replace the gas phase with nitrogen. After that, the solution was kept at 80 ° C., and the pre-emulsion was added dropwise over 2 hours. After the addition, the temperature was maintained at 80 ° C. for another hour to complete the polymerization. Thereafter, the mixture was neutralized with triethylamine until the pH became 8, thereby obtaining an intended aqueous resin emulsion. The obtained resin emulsion showed good results in both the storage stability test and the water resistance test, and the grid amount was 0.03.
And few.

[0024]

According to the present invention, a film having excellent water resistance is formed by copolymerizing the macromonomer of the present invention having a specific chemical structure with another copolymerizable monomer in an aqueous medium. An aqueous resin emulsion can be produced, and the emulsion is suitable as a paint, a coating material, an adhesive, a pressure-sensitive adhesive, and the like.

Claims (1)

[Claims] 1. A method for producing an aqueous resin emulsion, comprising copolymerizing the following macromonomer and other radically polymerizable monomers in an aqueous medium in the presence or absence of an emulsifier. Macromonomer: (a) a macromonomer having a radical polymerizable group at one end of silicone or a hydrophobic vinyl polymer, (b) polyalkylene glycol mono (meth) acrylate or polyalkylene glycol monoalkyl ether mono (meth) acrylate; If desired, a copolymer obtained by copolymerizing (c) other radically polymerizable monomers, wherein the ratio of the (a) macromonomer unit is 40 to 40% based on the total amount of all structural units. 1% by weight, and the proportion of the monomer unit (b) is 60 to 99% by weight.
And (c) a macromonomer having a radical polymerizable group at one end of a copolymer having a monomer unit ratio of 0 to 15% by weight