JPH05140255A - Preparation of aqueous resin dispersion - Google Patents

Abstract

PURPOSE:To prepare an aq. resin dispersion of a graft polymer obtd. by the emulsion polymn. in an aq. medium of a radical polymerizable silicone macromonomer and other radical polymerizable monomer. CONSTITUTION:A silicone macromonomer having a radical polymerizable group is dissolved in other monomer copolymerizable with the macromonomer to obtain a mixture of the monomers, which is dispersed in an aq. medium in the presence of an anionic surfactant by emulsification and copolymerized in the presence of a water-soluble radical polymn. initiator to prepare the objective aq. resin dispersion.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an aqueous emulsion polymerization method of a radical-polymerizable silicone macromonomer and another radical-polymerizable monomer. According to the present invention, an aqueous resin suitable as a paint or an adhesive is used. A dispersion is easily obtained.

[0002]

2. Description of the Related Art In recent years, a high molecular weight monomer having a polymerizable group at the end of a molecule, that is, a macromonomer, which is called a graft polymer by a macromonomer method, is copolymerized with another copolymerizable monomer. The structurally controlled graft polymer obtained in this manner has attracted attention as a highly functional polymer material and is used as a coating material, an adhesive, a polymer additive, or the like.

Conventionally, the production of a graft polymer by the macromonomer method has been generally carried out by solution polymerization in which a macromonomer and another copolymerizable monomer are polymerized in an organic solvent, or suspension polymerization in an aqueous medium. It was However, solution-type graft polymers cannot meet the demands of the era of pollution-free and resource saving. On the other hand, the graft polymer obtained by suspension polymerization undergoes phase separation into a liquid phase and a solid phase, so that it is liquid as an aqueous dispersion. There is a problem that it is difficult to handle, and there is a strong demand for an aqueous emulsion that replaces them, and various studies have been made on the method for producing such an aqueous emulsion.

For example, an aqueous emulsion of a graft polymer using a macromonomer having a skeleton of poly (meth) acrylic acid alkyl ester, polystyrene or poly (styrene / acrylonitrile) is conventionally used for low molecular weight monomers. In such a general aqueous emulsion polymerization method, since the polymerization system is extremely unstable and a large amount of grids are generated, the following emulsion polymerization method or microsuspension polymerization method has been proposed. That is, in Japanese Patent Application Laid-Open No. 1-318027, a pre-emulsion to be subjected to polymerization, that is, an unpolymerized emulsified dispersion composed of a polymerizable component, is provided with a specific surfactant such as sodium sulfosuccinate as an emulsifier for preparing the same. An emulsion polymerization method has been proposed in which the emulsion dispersion is used, and the particle size of the emulsion dispersion is refined to about 1 μm, followed by polymerization with a water-soluble polymerization initiator, and JP-A-3-1631.
JP-A No. 1-318027 discloses an oil-soluble radical polymerization initiator, which is dissolved in a liquid comonomer together with a macromonomer in JP-A No. 03-18027. A microsuspension polymerization method has been proposed in which a surfactant is emulsified and dispersed in a fine particle size to perform polymerization.

On the other hand, a silicone-based graft polymer obtained by polymerizing a silicone-based macromonomer such as polydimethylsiloxane (hereinafter referred to as a silicone-based macromonomer) with another copolymerizable monomer is used as a branch component. Since the silicone unit has unique properties such as water / oil repellency, stain resistance and low friction, it is extremely useful as a coating agent or coating material component for various base materials (for example, JP-A-63). No. 227670, etc.), an aqueous emulsion type has been earnestly desired for the graft polymer as well, but almost no prior art relating to an aqueous emulsion of a silicone-based graft polymer is found.

[0006]

The present inventors have adopted the microsuspension polymerization method disclosed in JP-A-3-163103 when aqueous polymerization of silicone macromonomers and other monomers. It has been found that an emulsion having excellent physical properties can be obtained, and a patent application has been filed for the invention (Japanese Patent Application No. 3-184145).
No.), after that, even if the operationally complicated microsuspension polymerization method is not intentionally adopted, a particular problem occurs in the emulsion polymerization method adopted in the general emulsion polymerization of low molecular weight monomers. The inventors have found that an aqueous emulsion can be obtained without any problems, and completed the present invention.

That is, according to the present invention, a silicone-based macromonomer having a radical-polymerizable group is dissolved in another vinyl monomer copolymerizable with the macromonomer, and the resulting monomer mixture is treated with an anionic surfactant. A method for producing an aqueous resin dispersion, which comprises emulsifying and dispersing it in an aqueous medium in the presence of an agent, and copolymerizing it with a water-soluble radical polymerization initiator. As described above, the main part of the technical means adopted in the present invention is the technique conventionally used in the emulsion polymerization of general low molecular weight monomers. When this technique is used in the case of using a macromonomer having a vinyl polymer such as poly (meth) acrylic acid alkyl ester, polystyrene or poly (styrene / acrylonitrile) as a skeleton, a large amount of grid is generated as described above. Since it is generated, it was difficult to apply to emulsion polymerization of such a macromonomer, but in the present invention using a silicone-based macromonomer as a macromonomer, an aqueous emulsion having practically satisfactory physical properties can be obtained. .. The reason for this is not clear, but it is speculated that the remarkable hydrophobicity of the silicone-based macromonomer or the silicone-based graft polymer may be due to the increased stability of micelles in emulsion polymerization.

The present invention will be described in more detail below. Silicone Macromonomer The silicone macromonomer in the present invention is a high molecular weight monomer having a silicone skeleton and having a radical polymerizable group at one end, and its preferable number average molecular weight is
1,000 to 1 in terms of polystyrene equivalent number average molecular weight measured by gel permeation chromatography
0,000, more preferably a number average molecular weight of 2,0
It is 00-50,000. If the number average molecular weight of the macromonomer is less than 1,000, the branch polymer in the obtained graft polymer is too short, and the properties derived from silicone such as lubricity, releasability, and weather resistance are hard to be expressed. When the number average molecular weight of exceeds 10,000,
The copolymerizability with the vinyl monomer to be copolymerized is poor, and the yield of the graft polymer is low. Examples of the radically polymerizable group include an acryloyl group, a methacryloyl group, a styryl group, an allyl group, a vinylbenzyl group, a vinyl ether group, a vinylalkylsilyl group, a vinylketone group and an isopropenyl group.

As a method for producing the silicone-based macromonomer, a known method can be adopted. For example, a living polymer is obtained by anionic polymerization of a cyclic siloxane using lithium trialkylsilanolate as an initiator, and γ-methacryloxypropyl. A method of reacting dimethylmonochlorosilane (JP-A-59-78236) or a method of obtaining a silicone macromonomer as a condensate of a silicone containing a terminal silanol group and an organic silicon compound (JP-A-58-167606). And JP-A-60-123518).

In the present invention, the silicone-based macromonomer must be emulsified and dispersed in an aqueous medium in a state of being dissolved in the vinyl monomer to be copolymerized with the macromonomer. By adopting such means, micelles containing both silicone macromonomer and copolymerization monomer can be formed in one emulsified fine particle, that is, micelle, and the copolymerization thereof easily occurs, so that the grafting ratio is high. A polymer is obtained.

Copolymerization monomer The monomer to be copolymerized with the silicone macromonomer is
Any vinyl monomer or vinyl monomer mixture that can be emulsified in an aqueous medium may be used, and a vinyl monomer or monomer mixture that is liquid at room temperature is more preferable. Specifically, methyl methacrylate, ethyl (meth) acrylate, butyl (meth) acrylate, isobutyl (meth)
(Meth) acrylic acid esters such as acrylate, tert-butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, lauryl (meth) acrylate and isobornyl (meth) acrylate, fluorine such as polyfluoroacrylate and perfluoroalkyl acrylate Acrylates, silicone-containing acrylates such as acryloyloxypropyltrimethoxysilane, styrene compounds such as styrene, α-methylstyrene, p-methylstyrene, and vinyl esters such as (meth) acrylonitrile, vinyl acetate, vinyl propionate, etc. Is mentioned.

Further, the following monomers can also be used in combination with the above monomers. Other vinyl monomers that can be used in combination with the vinyl monomer include methyl acrylate, 2-hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate,
Hydrophilic vinyl monomers such as (meth) acrylamide, N-methylol (meth) acrylamide, polyethylene glycol mono (meth) acrylate, polypropylene glycol mono (meth) acrylate, (meth) acrylic acid, vinylpyrrolidone and vinylpyridine, divinyl Examples thereof include multifunctional vinyl monomers such as benzene, diallyl phthalate and diethylene glycol diacrylate, stearyl (meth) acrylate, behenyl (meth) acrylate, maleic anhydride, butadiene, isoprene and vinylidene chloride. In the present invention,
From the viewpoint of emulsion stability, it is preferable to use a carboxyl group-containing monomer such as (meth) acrylic acid in combination. A preferable copolymerization ratio of the silicone-based macromonomer and the copolymerization monomer is 1 to 50% by weight of the macromonomer and 50 to 99% by weight of the copolymerization monomer. The amount of macromonomer used is 5
If it exceeds 0% by weight, the emulsion stability is poor and a large amount of grids are generated. When a polyfunctional vinyl monomer is used as the copolymerizable monomer, its preferable amount used is preferably 5% by weight or less based on the total amount of all the monomers.

Emulsifier The emulsifier used in the present invention is an anionic surfactant, and specifically, an alkali metal salt of alkylbenzenesulfonic acid such as sodium dodecylbenzenesulfonate; sodium alkylnaphthalenesulfonate and alkyldiphenyletherdisulfonic acid. Alkali metal salts of sodium and naphthalene sulfonic acid formalin condensates; sodium di-2-ethylhexyl sulfosuccinate, sodium polycyclic phenyl polyethoxysulfosuccinate, sodium polyoxyethylene alkyl allyl ether sulfosuccinate and polyoxyethylene lauryl ether sulfosuccinate. Alkali metal sulfosuccinates such as sodium; Alkali sulfates such as sodium lauryl sulfate and sodium stearyl sulfate Metal salts; sodium polyoxyethylene alkylene ether sulfate such as sodium polyoxyethylene lauryl ether sulfate and sodium polyoxyethylene octylphenyl ether sulfate.

Further, a nonionic surfactant can be used in combination with the above anionic surfactant. Examples of the nonionic surfactant include Emulgen 910, Emulgen 930, Emulgen 938 (all manufactured by Kao Corporation),
Newcol 563, Newcol 566 [Nippon Emulsifier Co., Ltd.
Manufactured by Toho Kagaku Co., Ltd .; polyoxyethylene nonylphenyl ether; Emulgen 81
0, Emulgen 840S [above Kao Corporation], Newcol
860, Newcol 804 [all manufactured by Nippon Emulsifier Co., Ltd.] and other polyoxyethylene octyl phenyl ethers; Leodol TW-L20, Leodol TW-S120 [all manufactured by Kao Corporation], Newcol 25, Newcol 65 [all manufactured by Nippon Emulsifier Co., Ltd.] ], Zorbon T-20, Zorbon T-60
Polyoxyethylene sorbitan monoalkylate such as those manufactured by Toho Kagaku Co., Ltd .; polyethylene glycol distearate and polyoxyethylene cetyl ether. Use of a nonionic surfactant having an HLB value of 10 or more further improves the stability of the aqueous emulsion dispersion during polymerization. A preferable ratio of the anionic surfactant and the nonionic surfactant is 10 to 90% by weight to 90 to 10% by weight, more preferably 10 to 40% by weight.
% To 90-60% by weight.

The preferred amount of the above surfactant is 100, which is the total amount of the silicone macromonomer and the copolymerized monomer.
The amount is 0.1 to 10 parts by weight, and in that case, the amount of water as the polymerization medium may be about 30 to 100 parts by weight. The smaller the amount of the surfactant used, the better the physical properties such as water resistance of the resulting aqueous resin dispersion. A liquid monomer mixture prepared by dissolving a silicone macromonomer in a copolymerized monomer was added to an aqueous medium containing the above surfactant, and the mixture was stirred to prepare an emulsified dispersion liquid. By polymerizing with a radical polymerization initiator, an aqueous resin dispersion comprising the silicone-based graft polymer, which is the object of the present invention, can be obtained. A suitable polymerization temperature is 40 to 90 ° C. After adding the following polymerization initiator to the emulsified dispersion,
The temperature may be raised as it is and the polymerization may be carried out under stirring, or the emulsion dispersion and the aqueous solution of the polymerization initiator may be stored in separate dropping funnels, respectively, and they may be put in a polymerization container in which a heated aqueous medium is charged in an appropriate amount. Polymerization may be carried out with stirring while dropping.

Polymerization initiator The polymerization initiator used in the present invention is a water-soluble radical polymerization initiator, and examples thereof include the following inorganic peroxides, organic peroxides and azo compounds. .. That is, as the inorganic peroxide, hydrogen peroxide,
Examples thereof include potassium persulfate, sodium persulfate and ammonium persulfate, and examples of the organic peroxides include tertiary butyl peroxymaleic acid, succinic acid peroxide and tertiary butyl hydroperoxide, and azo compounds. 2,2'-azobis (2- (N-benzylamidino) propane) hydrochloride, 2,2'-azobis (2- (N-allylamidino))
Propane) hydrochloride, 2,2'-azobis (2-amidinopropane) hydrochloride, 2,2'-azobis (2- (N-
(2-Hydroxyethyl) amidino) propane) hydrochloride and 2,2′-azobis (2-methyl-N- (1,1
-Bis (hydroxymethyl) -2-hydroxyethyl)) propionamide, 2,2'-azobis (2-methyl-N- (hydroxyethyl))-propionamide and the like. The preferred amount of the polymerization initiator used is 0.5 to 5% by weight based on the total amount of the silicone macromonomer and the copolymerization monomer.

[0017]

EXAMPLES The present invention will be described more specifically with reference to examples. In addition, "part" in each example means a "weight part." Example 1 10 parts of one-end-end methacryloyl group-type silicone macromonomer (AK-5 manufactured by Toagosei Chemical Industry Co., Ltd., number average molecular weight of 5,000) was dissolved in a mixed solution of 89 parts of butyl methacrylate and 1 part of methacrylic acid. Then, the obtained solution was emulsified and dispersed in 43 parts of deionized water using 2 parts of sodium lauryl sulfate as an emulsifier. The average particle size of the obtained emulsified dispersion was 2.11 μm. 70 parts of deionized water was added to a 1 L flask equipped with a stirrer, thermometer, and condenser, and the internal temperature was adjusted to 80 while blowing nitrogen gas.
The temperature was maintained at ± 1 ° C., and then 10 parts of a 10% by weight aqueous solution of ammonium persulfate and 145 parts of an emulsion dispersion of the above-mentioned monomer mixture were added dropwise from a dropping funnel over 5 hours while stirring. After the dropping was completed, the reaction was continued for 2 hours to complete the polymerization. During the polymerization, apart from a small amount of agglomerate attached to the wall of the flask, separation and blocking did not occur, and it was stable. As a result of filtering the obtained resin dispersion through a 200-mesh net, the grid amount was 0.1 part or less. Measured by gel permeation chromatography,
The polystyrene-reduced number average molecular weight of the obtained resin was 18.
The average particle diameter of the dispersion resin was 0,000, the weight average molecular weight was 107,100, and the average particle diameter was 0.38 μm. The distribution was narrow [laser diffraction particle size manufactured by Hikiba Seisakusho Co., Ltd.]. It was measured with a distribution measuring device LA-500]. In addition, the conversion rate of the macromonomer (the ratio of the macromonomer actually polymerized to the macromonomers used for the polymerization) was 72%.

Example 2 30 parts butyl methacrylate, 4 methyl methacrylate
In a mixed solution of 7 parts and 3 parts of methacrylic acid, 20 parts of a methacryloyl group-type silicone macromonomer (FM0725 manufactured by Chisso Corporation, number average molecular weight 10,000) was dissolved, and polyoxyethylene octylphenyl ether sodium sulfate 2 The above mixture was emulsified and dispersed in 50 parts of deionized water in the same manner as in Example 1 using 0.5 part as an emulsifier. The average particle size of the obtained emulsified dispersion was 2.05 μm. The obtained emulsified dispersion was polymerized in the same manner as in Example 1. During the polymerization, apart from a small amount of agglomerate adhering to the wall of the flask, separation and blocking did not occur, and it was stable. The obtained emulsion polymer is 200
When filtered with a mesh net, the grid amount is 0.1
It was less than a part. The number average molecular weight of the resin was 145,000, the weight average molecular weight was 104,200, and the average particle diameter of the dispersed resin was 0.35 μm.

[0019]

EFFECTS OF THE INVENTION According to the present invention, a silicone-based aqueous resin dispersion having excellent physical properties made of a resin having a fine particle size can be obtained without the complicated operation of refining the particle size of the pre-emulsion to about 1 μm. Easily obtained. Furthermore, the resin dispersion has a high graft polymer content and a small amount of unreacted silicone macromonomer, and is excellent in various physical properties. That is, the aqueous resin dispersion obtained by the method of the present invention is excellent in various properties such as water repellency, lubrication, mold release, antifouling, weather resistance, gas permeation, etc. Prevention, paper sticking prevention, ice accretion prevention, snow accretion prevention, weather resistance, etc.) and coating agents (magnetic tape, thermal recording film, photosensitive recording film, etc.), adhesives, adhesives, pigments and fillers, etc. It is suitable for use as a dispersion improver, an antistatic agent and a resin modifier.

Claims (1)

[Claims] 1. A silicone macromonomer having a radical polymerizable group is dissolved in another vinyl monomer copolymerizable with the macromonomer, and the resulting monomer mixture is added in the presence of an anionic surfactant. A method for producing an aqueous resin dispersion, which comprises emulsifying and dispersing in an aqueous medium and copolymerizing with a water-soluble radical polymerization initiator.