JP5618131B2 - Method for producing emulsion - Google Patents

Description

  The present invention relates to a method for producing an emulsion.

  In recent years, in the paint field, conversion from a solvent-based paint using an organic solvent as a medium to an aqueous paint using a water as a medium has been attempted in consideration of the global environment, the painting work environment, and the like. In particular, emulsion-based water-based paints in which resin components are dispersed in water are excellent in drying properties and can be reduced in viscosity even when the concentration of non-volatile components is increased, so that not only paints but also adhesives, adhesives, and paper treatments Widely used in agents and fiber treatment agents. Along with the rapid expansion of applications of water-based paints, there is a demand for a highly productive production method that not only has performance but also has a short production time and good polymerization stability.

  For example, Patent Document 1 discloses a production method for shortening the production time by producing an emulsion in which a polymer having a multilayer structure is dispersed in water by carrying out the first-stage polymerization by batch polymerization instead of dropping polymerization. Has been. A coating film obtained from an aqueous coating material containing an emulsion obtained by this production method exhibits excellent weather resistance. Furthermore, since it has a multilayer structure, two contradictory properties such as the hardness of the coating film surface and the flexibility of the coating film can be achieved.

JP 2009-269972 A

However, the production method described in Patent Document 1 sometimes causes problems in polymerization stability, for example, a large amount of aggregates are generated during the polymerization and the heat generated by the polymerization is not stable.
Then, the objective of this invention is providing the manufacturing method which can superpose | polymerize stably the emulsion for water-based coating materials which forms the coating film excellent in water resistance and a weather resistance in a short manufacturing time.

In the present invention, a polyorganosiloxane polymer obtained by polymerizing a dimethylsiloxane cyclic oligomer and a graft-crossing agent comprising a hydrolyzable silyl group-containing radical polymerizable monomer and a radical polymerizable monomer mixture (a) are added to a reaction vessel. Further, the present invention relates to a method for producing an emulsion in which after emulsion polymerization at a pH of 9 or more is carried out, emulsion polymerization is carried out while dropping the radical polymerizable monomer mixture (b) to form a polymer .

  By the production method of the present invention, a highly productive emulsion having a short production time and good polymerization stability can be produced. Furthermore, a coating film obtained from an aqueous coating material containing this emulsion can form a coating film excellent in water resistance and weather resistance.

In the present invention, after emulsion polymerization is performed on a part of the radically polymerizable monomer mixture (radical polymerizable monomer mixture (a)) subjected to polymerization and the polyorganosiloxane copolymer ( Polymerization step 1),
Emulsion polymerization is carried out while dropping the remaining radical polymerizable monomer mixture (radical polymerizable monomer mixture (b)) (polymerization step 2).

  By carrying out the polymerization step 1, not only can the polymerization time be shortened but also a high molecular weight can be easily achieved compared to the method in which the total amount of the radical polymerizable monomer mixture to be subjected to polymerization is dropped, the water resistance In addition, an aqueous coating material excellent in weather resistance can be produced.

[Polymerization step 1]
In the polymerization step 1 of the present invention, emulsion polymerization is carried out in the presence of a polyorganosiloxane copolymer. An aqueous coating material excellent in water resistance and weather resistance can be produced by emulsion polymerization of the radical polymerizable monomer mixture (a) in the presence of the polyorganosiloxane copolymer.
Furthermore, it is necessary to carry out under conditions of pH 9 or higher. By conducting emulsion polymerization at a pH of 9 or more, the polymerization can be stably performed particularly in the polymerization step 2.

Polyorganosiloxane Copolymer The polyorganosiloxane polymer of the present invention is, for example, dimethyldialkoxysilanes such as dimethyldimethoxysilane, dimethyldiethoxysilane, hexamethylcyclotrisiloxane, octamethylcyclotetrasiloxane, decamethylcyclohexane. Under acidic or alkaline conditions, dimethylsiloxane cyclic oligomers such as pentasiloxane, dodecamethylcyclohexasiloxane, tetradecamethylcycloheptasiloxane, dimethylcyclics (dimethylsiloxane cyclic oligomer 3-7-mer mixture), dimethyldichlorosilane, etc. Can be synthesized by polymerization. It is preferable to use a dimethylsiloxane cyclic oligomer from the viewpoint of excellent performance such as thermal stability and cost of the obtained resin.

  Further, it is more preferable to use a polyorganosiloxane polymer obtained by polymerizing a dimethylsiloxane cyclic oligomer and a graft-crossing agent comprising a hydrolyzable silyl group-containing radical polymerizable monomer. This is because the polyorganosiloxane polymer and the radically polymerizable monomer mixture (a) can be graft-polymerized to exhibit excellent stain resistance, weather resistance, water resistance and frost damage resistance of the coating film.

  The mass average molecular weight of the polyorganosiloxane polymer is preferably 10,000 or more, and more preferably 50,000 or more. When the mass average molecular weight of the polyorganosiloxane polymer is 10,000 or more, sufficient durability is easily obtained for the formed coating film.

  It is preferable that a polyorganosiloxane polymer is 0.5-25 mass parts with respect to 100 mass parts of radically polymerizable monomers. If it is less than 0.5 parts by mass, the weather resistance, water resistance and flexibility of the coating film tend to be lowered. More preferably, it is 1 part by mass or more. Moreover, when the usage-amount exceeds 25 mass parts, it exists in the tendency for the softness | flexibility of a coating film, a weather resistance, water resistance, and stain resistance to fall. More preferably, it is 20 parts by mass or less. More preferably, it is 2-15 mass parts.

Radical polymerizable monomer mixture (a)
The following are mentioned as a monomer which can be used as a radically polymerizable monomer mixture (a).

Methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, i-butyl (meth) acrylate, sec-butyl (meth) acrylate, t-butyl (meth) acrylate, 2-ethylhexyl (meth) Alkyl (meth) acrylates having an alkyl group having 1 to 18 carbon atoms such as acrylate and stearyl (meth) acrylate; cycloalkyl (meth) acrylates such as cyclohexyl methacrylate; γ- (meth) acryloyloxypropylmethyldimethoxysilane Hydrolyzable silyl group-containing radical polymerizable monomers such as γ- (meth) acryloyloxypropyltrimethoxysilane; radical polymerizable carboxylic acid monomers such as acrylic acid, methacrylic acid and itaconic acid; hydroxypolyethyleneoxy Terminal-hydroxy type polyalkylene oxide group-containing radical polymerizable monomers such as domono (meth) acrylate and hydroxypolypropylene oxide mono (meth) acrylate; alkyl group-terminated polyalkylene oxide groups such as methoxypolyethylene oxide mono (meth) acrylate Photo-stabilizing action of radically polymerizable monomer; 1,2,2,6,6-pentamethyl-4-piperidyl (meth) acrylate, 2,2,6,6-pentamethyl-4-piperidyl (meth) acrylate (Meth) acrylate having a UV-absorbing component such as 2- [2′-hydroxy-5 ′-(meth) acryloyloxyethylphenyl] -2H-benzotriazole; 2-aminoethyl (meta) ) Aminoalkyl (meth) a such as acrylate Acrylates; amide group-containing radical polymerizable monomers such as (meth) acrylamide; metal-containing radical polymerizable monomers such as zinc di (meth) acrylate; (meth) acrylonitrile, benzyl (meth) acrylate, isobornyl ( Other (meth) acrylic monomers such as meth) acrylate and methoxyethyl (meth) acrylate; aromatic vinyl monomers such as styrene and methylstyrene; conjugated diene monomers such as 1,3-butadiene and isoprene A radical polymerizable monomer such as vinyl acetate, vinyl chloride or ethylene.

Moreover, it is preferable to use a monomer having two or more radical polymerizable groups in the radical polymerizable monomer mixture (a) because the weather resistance, water resistance and blocking resistance of the coating film are improved.
Specific examples of the monomer having two or more radically polymerizable groups include the following. Ethylene glycol di (meth) acrylate, tetraethylene glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, propylene glycol di (meth) acrylate, polypropylene glycol di (meth) acrylate, 1,3-butylene glycol di (meth) ) Acrylate, 1,6-hexanediol di (meth) acrylate, neopentylglycol di (meth) acrylate, 2-hydroxy-1,3-di (meth) acryloxypropane, 2,2-bis [4- (acrylic) Loxyethoxy) phenyl] propane, 2,2-bis [4- (methacryloxyethoxy) phenyl] propane, 2,2-bis [4- (acryloxy-polyethoxy) phenyl] propane, 2,2-bis [4- ( Methacryloxy Polyet Si) phenyl] propane, 2-hydroxy-1-acryloxy-3-methacryloxypropane, ethylene oxide modified bisphenol A di (meth) acrylate, propylene oxide modified bisphenol A di (meth) acrylate, ethylene oxide modified hydrogenated bisphenol A di (Meth) acrylate, propylene oxide modified hydrogenated bisphenol A di (meth) acrylate, epoxy (meth) acrylate obtained by adding hydroxyalkyl (meth) acrylate such as hydroxy (meth) acrylate to diglycidyl ether of bisphenol A, polyoxy Diester compound of diol such as alkyleneated bisphenol A di (meth) acrylate and (meth) acrylic acid; trimethylolpropane tri (meth) acrylate, teto Methylolmethane tri (meth) acrylate, tetramethylolmethane tetra (meth) acrylate, pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol penta (meth) acrylate, dipentaerythritol hexa (meth) acrylate A compound having three or more hydroxyl groups per molecule and a polyester compound of (meth) acrylic acid; allyl (meth) acrylate, divinylbenzene, triallyl (iso) cyanurate, diallyl iso (tere) phthalate, diallyl isocyanurate, Maleic acid diallyl tris (2-acryloyloxyethylene) isocyanurate, ε-caprolactone modified tris (acryloxyethyl) isocyanurate. Among them, triallyl cyanurate, triallyl isocyanurate, diallyl iso (tere) phthalate, diallyl isocyanurate, diallyl maleate, etc. are preferable, and triallyl cyanurate having 3 allyl groups, triallyl isocyanurate is more used. preferable.

  Furthermore, it is preferable to use hydroxylalkyl (meth) acrylate because the blending stability in producing an aqueous coating material, the stain resistance, weather resistance, water resistance, and adhesion to various substrates of the coating film are improved. The proportion of hydroxyalkyl (meth) acrylate contained in all monomers (radical polymerizable monomer mixture (a) and radical polymerizable monomer mixture (b)) is preferably 0.1 to 15% by mass. 0.5 to 12% by mass is more preferable. If the amount of hydroxylalkyl (meth) acrylate contained in all the monomers is 0.1% by mass or more, an effect is obtained, and if it is 15% by mass or less, deterioration of water resistance and weather resistance of the coating is suppressed. it can.

  Furthermore, it is preferable to use a radically polymerizable monomer containing a self-crosslinkable functional group because the coating film has improved blocking resistance, stain resistance, weather resistance, water resistance, and adhesion to various substrates. Self-crosslinkable functional group-containing radically polymerizable monomer means that the self-crosslinkable functional group remaining in the obtained polymer is chemically stable while being stored as a dispersion at room temperature. A monomer that reacts with side chain functional groups by drying, heating, or other external factors to form a chemical bond between the side chains.

  Examples of the self-crosslinkable functional group-containing radical polymerizable monomer include oxirane group-containing radical polymerizable monomers such as glycidyl (meth) acrylate, N-methylol (meth) acrylamide, and N-butoxymethyl (meth) acrylamide. And an alkylol or alkoxyalkyl compound of a radically polymerizable amide such as N-methoxymethyl (meth) acrylamide. Two or more of these may be selected and used as necessary.

  The self-crosslinkable functional group-containing radical polymerizable monomer is 0.2 to 10% by mass in all monomers (radical polymerizable monomer mixture (a) and radical polymerizable monomer mixture (b)). It is preferable to contain, and it is more preferable to contain 0.5-8 mass%. An effect is acquired by containing 0.2 mass% or more, and if it is 10 mass% or less, the fall of the water resistance of a coating film and a weather resistance can be suppressed.

Surfactant The surfactant of the radical polymerizable monomer 100 parts by weight, preferably contains 0.1 to 10 parts by weight. By making the surfactant 0.1 mass part or more, the polymerization stability and the storage stability of the emulsion are improved. In addition, by making the surfactant 10 parts by mass or less, blending stability when blending an emulsion into an aqueous coating material without impairing the water resistance of the coating film, temporal stability of the aqueous coating material, etc. Can be maintained. A more preferable content is 0.5 to 8 parts by mass.

Examples of usable surfactants include various anionic, cationic or nonionic surfactants, and polymer emulsifiers. A reactive surfactant having a radical polymerizable bond in the surfactant component can also be used.
From the viewpoint of improving weather resistance, it is preferable to use a phosphate ester type reactive surfactant in combination. A preferable usage amount is 0.05 to 5 parts by mass with respect to 100 parts by mass of all monomers. When the amount used is 5 parts by mass or less, a decrease in water resistance and weather resistance of the coating film can be suppressed. More preferably, it is 0.1 to 3 parts by weight.

  The phosphate ester type reactive surfactant can be obtained as a commercial product. Specific examples thereof include FP-80, FP-100, FP-120, FP-160, FP-200, FP-125, and Asahi Denka Kogyo Co., Ltd., surfmer series manufactured by Toho Chemical Industry Co., Ltd. Adecalia soap series PP-70, PPE-710 and the like manufactured by the company are listed. One or more of these can be selected and used as necessary.

As the radical polymerization initiator , a known one used for radical polymerization can be used. Specific examples include persulfates such as potassium persulfate, sodium persulfate, and ammonium persulfate; azobisisobutyronitrile, 2,2′-azobis (2-methylbutyronitrile), 2,2′-azobis ( 2,4-dimethylvaleronitrile), 2,2′-azobis (4-methoxy-2,4-dimethylvaleronitrile), oil-soluble azo compounds such as 2-phenylazo-4-methoxy-2,4-dimethylvaleronitrile 2,2′-azobis {2-methyl-N- [1,1-bis (hydroxymethyl) -2-hydroxyethyl] propionamide}, 2,2′-azobis {2-methyl-N- [2 -(1-hydroxyethyl)] propionamide}, 2,2′-azobis {2-methyl-N- [2- (1-hydroxybutyl)] propionamide}, 2,2′-azobis [2- (5-Methyl-2-imidazolin-2-yl) propane] and its salts, 2,2′-azobis [2- (2-imidazolin-2-yl) propane] and its salts, 2,2 ′ -Azobis [2- (3,4,5,6-tetrahydropyrimidin-2-yl) propane] and its salts, 2,2'-azobis {2- [1- (2-hydroxyethyl) -2-imidazoline- 2-yl] propane} and salts thereof, 2,2′-azobis (2-methylpropionamidine) and salts thereof, 2,2′-azobis (2-methylpropyneamidine) and salts thereof, 2,2′- Water-soluble azo compounds such as azobis [N- (2-carboxyethyl) -2-methylpropionamidine] and salts thereof; benzoyl peroxide, cumene hydroperoxide, t-butyl high B peroxide, t- butyl peroxy-2-ethylhexanoate, organic peroxides such as t-butyl peroxy isobutyrate and the like. These can be used alone or as a mixture of two or more.

  The addition amount of the radical polymerization initiator is usually 0.01 to 10 parts by mass with respect to 100 parts by mass of the radical polymerizable monomer. 01-0.5 mass part is preferable. More preferably, it is 0.01-0.15 mass part, More preferably, it is 0.01-0.1 mass part.

Polymerization temperature The polymerization temperature in the polymerization step 1 is preferably started at 70 ° C. or less in consideration of heat generated by emulsion polymerization all at once. 60 ° C. or lower is more preferable, and 55 ° C. or lower is more preferable. In addition, when the decomposition temperature of a polymerization initiator is higher than the said polymerization temperature, it is preferable to use reducing agents, such as sodium bisulfite, ferrous sulfate, ascorbate, in combination with a radical polymerization initiator.

In the conditional polymerization step 1 of pH, emulsion polymerization is collectively performed under the condition of pH 9 or higher. In addition, performing emulsion polymerization under the condition of pH 9 or higher means that the pH of the solution containing the radical polymerizable monomer mixture (a) existing in the reaction vessel before introducing the reducing agent or initiator is 9 or higher. Means. Furthermore, it is more preferable to polymerize at pH 10 or higher. By setting the pH to 9 or more, the polymerization stability is improved, aggregates generated during the polymerization are reduced, and the heat generated by the polymerization can be stabilized. Specific examples of the basic compound added to adjust the pH to 9 or more include the following.
Ammonia, trimethylamine, triethylamine, propylamine, dibutylamine, amylamine, 1-aminooctane, 2-dimethylaminoethanol, ethylaminoethanol, 2-diethylaminoethanol, 1-amino-2-propanol, 2-amino-1-propanol, 2-amino-2-methyl-1-propanol, 3-amino-1-propanol, 1-dimethylamino-2-propanol, 3-dimethylamino-1-propanol, 2-propylaminoethanol, ethoxypropylamine, aminobenzyl Alcohol, morpholine, sodium hydroxide, potassium hydroxide. Among these, ammonia is preferable from the viewpoint of volatility.

[Polymerization step 2]
In the polymerization step 2 of the present invention, after the polymerization step 1, emulsion polymerization is performed while dropping the radical polymerizable monomer mixture (b).

Radical polymerizable monomer mixture (b)
The radical polymerizable monomer mixture (b) is not particularly limited, and examples thereof include the monomers exemplified in the radical polymerizable monomer mixture (a). Furthermore, it is preferable to use a carbonyl group and / or aldehyde group-containing radical polymerizable monomer, since more excellent coating properties and coating properties can be expressed. These monomers can use 2 or more types as needed.

  Examples of the carbonyl group and / or aldehyde group-containing radical polymerizable monomer include acrolein, diacetone acrylamide, formyl styrene, and vinyl alkyl ketone. Among them, vinyl methyl ketone having 4 to 7 carbon atoms, vinyl ethyl ketone, vinyl isobutyl ketone, (meth) acryloxyalkylpropanal, (meth) acrylamide, pivalin aldehyde, diacetone (meth) acrylate, acetonyl acrylate Acetolecetoxyethyl (meth) acrylate is preferable, and acrolein, diacetone acrylamide, and vinyl methyl ketone are more preferable.

  The carbonyl group and / or aldehyde group-containing radical polymerizable monomer is 0.2 to 10 in the whole monomer (radical polymerizable monomer mixture (a) and radical polymerizable monomer mixture (b)). It is preferable to contain the mass%, and it is more preferable that it is 0.5-8 mass%.

  Furthermore, an organic hydrazine compound having at least two hydrazino groups in the molecule (hereinafter referred to as “a”) in a dispersion of a polymer obtained by polymerization using a carbonyl group and / or aldehyde group-containing radical polymerizable monomer. It is preferable to add a “hydrazine compound” because the water resistance and weather resistance of the coating film are improved. This effect is considered to be manifested by the progress of the crosslinking reaction between the carbonyl group in the polymer and the hydrazino group of the blended hydrazine compound in the step of drying after coating.

 Examples of the hydrazine compound include ethylene-1,2-dihydrazine, propylene-1,3-dihydrazine, butylene-1,4-dihydrazine, oxalic acid dihydrazide, malonic acid dihydrazide, succinic acid dihydrazide, glutaric acid dihydrazide, Adipic acid dihydrazide, sebacic acid dihydrazide, maleic acid dihydrazide, fumaric acid dihydrazide, isophthalic acid dihydrazide, itaconic acid dihydrazide, etc. 5-isopropylhydantoin, 1,3-bis (hydrazinocarboethyl) -5- (2-methylmercaptoethyl) hydantoin, 1-hydrazinocarboethyl-3-hydrazinocarboisopropyl-5- (2-methylmercaptoeth ) Include compounds having the hydantoin skeleton such as hydantoin.

  The ratio of the carbonyl group and / or aldehyde group-containing radical polymerizable monomer to the hydrazine compound is such that the carbonyl group and / or aldehyde group-containing radical polymerizable monomer contained in the radical polymerizable monomer mixture (b). When the number of moles of the body is (P) and the number of moles of hydrazino groups of the hydrazine compound to be blended in the polymer dispersion is (Q), the ratio (P) / (Q) is 0.1-10. Is preferable, and 0.8 to 2 is more preferable. If (P) / (Q) is 0.1 or more, it is easy to suppress a decrease in water resistance of the coating film due to unreacted hydrazine compound, and if (P) / (Q) is 10 or less, the coating film The degree of cross-linking increases, and the water resistance and weather resistance of the coating film are improved.

The type and amount of surfactant used in detergent polymerization step 2 may be the same as that described in the polymerization step 1.

Polymerization temperature The polymerization temperature in the polymerization step 2 is preferably performed in the range of 50 ° C to 90 ° C, more preferably 60 ° C to 80 ° C.

In the present invention, the radical polymerizable monomer mixture (a) and the radical polymerizable monomer mixture (b)
The mass ratio is preferably 25/75 to 80/20, and more preferably 25/75 to 60/40. When the mass ratio of the radical polymerizable monomer mixture (a) and the radical polymerizable monomer mixture (b) is 25/75 or more, not only the polymerization time can be shortened, but also an aqueous coating excellent in water resistance and weather resistance. The material can be manufactured. Moreover, if it is 80/20 or less, coexistence of two contradictory performances, such as the hardness of the coating-film surface and the softness | flexibility of a coating-film, for example will be attained.

[Emulsion]
In the emulsion obtained by this production method, it is preferable to adjust the pH of the dispersion to neutral to weakly alkaline, that is, about pH 6.5 to 11.0 by adding a basic compound after polymerization. Thereby, the stability of the obtained emulsion improves. The basic compound which can be used can be the same as the basic compound used when the pH is adjusted in the polymerization step 1.

  The particle diameter of the polymer obtained by this production method is preferably 30 to 300 nm in consideration of the balance between particle stability and coating film performance. More preferably, it is 50-200 nm, More preferably, it is 50 nm-130 nm. If the particle diameter is 30 nm or more, aggregates are unlikely to form during polymerization, and even a small amount of surfactant can be stably polymerized, and the water resistance of the coating film can be maintained. Moreover, since film-forming property improves at 300 nm or less, the coating film excellent in water resistance and a weather resistance is obtained.

  The aqueous coating material containing the emulsion obtained by this production method may further contain various pigments, antifoaming agents, pigment dispersants, leveling agents, anti-sagging agents, matting agents, ultraviolet absorbers, antioxidants, if necessary. You may contain a heat resistance improver, a slip agent, a preservative, etc. Moreover, you may mix and use hardening agents, such as another emulsion resin, water-soluble resin, a viscosity control agent, and melamines. The aqueous coating material forms a solid content with a polymer as a main component, the surfactant, an additive and the like, and is usually used in a state of a solid content of 20 to 80% by mass.

  Examples of the method of coating the aqueous coating material on the surface of various substrates include various coating methods such as spray coating, roller coating, bar coating, air knife coating, brush coating, dipping and flow coating. Can be selected. The aqueous coating material can obtain a coating film by drying at room temperature or by drying at 50 to 180 ° C.

  The water-based coating material obtained by this production method includes cement mortar, slate board, gypsum board, extruded board, foam concrete, metal, glass, porcelain tile, asphalt, wood, waterproof rubber material, plastic, and calcium silicate base. It is useful as a surface finish covering material for various materials such as wood, and is particularly useful as a water-based covering material for protecting a frame of a building, a civil engineering structure or the like.

  Hereinafter, the present invention will be described in detail with reference to examples. In the following description, “part” is based on mass. The evaluation of polymerization stability and aqueous coating material was carried out according to the following method.

<Preparation of aqueous coating material for evaluation>
When the MFT of the obtained emulsion exceeded 10 ° C., diethylene glycol monobutyl ether (hereinafter referred to as “BDG”) was added as a film forming aid to make the MFT 10 ° C. or less. Next, 0.5 g of RHEOLATE350 (RHEOX Co., Ltd., thickener) and 0.5 g of Surfynol DF-58 (Air Products Co., Ltd., antifoaming agent) are added to 100 g of the emulsion, The mixture was stirred and adjusted with Ford Cup # 4 by adding deionized water to about 30 seconds. Thereafter, filtration was carried out using a 100 mesh nylon bag to obtain an aqueous coating material for evaluation.

<Evaluation method>

(1) Measurement of pH The pH before the start of polymerization was sampled from a reaction vessel in a small amount, cooled to room temperature, then pH 6.86 standard buffer (Kishida Chemical's neutral phosphate pH standard solution) and pH 4.01. It measured using the pH meter (Horiba Seisakusho D-54) calibrated with the standard buffer solution (Kishida Chemical phthalate pH standard solution).

(2) Polymerization stability The obtained emulsion was passed through 100 mesh nylon, the remaining solid was dried at 105 ° C. for 3 hours, and the dry weight x (g) was measured. The aggregate generation rate (mass%) of the emulsion was calculated by the following formula.
Aggregate generation rate (% by mass) = x (g) / (Emulsion charge weight (g) × Emulsion theoretical solid content (% by mass)) × 100

(3) Polymerization temperature stability When the radically polymerizable monomer mixture (b) is dropped in a 2 L polymerization scale, the transition of the polymerization temperature is measured at intervals of 1 minute, and the fluctuation of the temperature is stabilized at the polymerization temperature. It was evaluated according to the following criteria as an index of sex. The smaller the swing width, the more stable the heat of polymerization, indicating that the polymerization control is easier.
○: Less than 1 ° C.
Δ: 1 ° C or higher and lower than 2 ° C.
X: 2 degreeC or more.

(4) A water-based coating for water resistance evaluation was coated on a zinc phosphate-treated steel plate (bonderite # 100-treated steel plate, thickness 0.8 mm, length 150 mm × width 70 mm) with a bar coater # 48 at 130 ° C. Force-dried for 20 minutes. Subsequently, it was allowed to cool to room temperature to obtain a coating plate for evaluation. This coating plate for evaluation was immersed in warm water at 50 ° C. for 100 hours, and the appearance of the coated film immediately after being pulled up and dried was visually observed and evaluated according to the following criteria.
(Double-circle): The whitening of the coating surface was little and it became a perfect clear coating film after drying.
◯: Some whitening of the painted surface was observed, but after drying, a clear coating film was formed in about 2 to 3 hours.
Δ: Some whitening of the painted surface was observed, and it was slightly cloudy even after 24 hours of drying, and barely after 48 hours, a clear coating film was formed.
X: The painted surface was considerably whitened and remained white after drying, and did not become a clear coating film until the end.

(5) Weather resistance A weather resistance test was conducted with a die plastic metal weather KU-R4-W type (manufactured by Daipura Wintes Co., Ltd.) using the same coating plate for evaluation as that used for the water resistance evaluation. At this time, the test cycle was irradiation 4 hours (spray 5 seconds / 15 minutes) / condensation 4 hours, UV intensity: 85 mW / cm 2, black panel temperature: 63 ° C. during irradiation / 30 ° C. during condensation, humidity: 50% during irradiation Under the conditions of RH / 96% RH during condensation, the 60 ° gloss retention after 1200 hours was used as an indicator of weather resistance, and evaluated according to the following criteria.
A: 90% or more.
○: 80% or more and less than 90%.
Δ: 60% or more and less than 80%.
X: Less than 60%, or with peeling / cracking of the coating film.

<Production Example 1> Preparation of polyorganosiloxane polymer aqueous dispersion The following raw material composition is premixed with a homomixer and forcibly emulsified with a pressure homogenizer at a pressure of 200 kg / cm ² to obtain a raw material pre-emulsion. It was.
Next, water (90 parts) and dodecylbenzenesulfonic acid (10 parts) were charged into a flask equipped with a stirrer, a reflux condenser, a temperature controller and a dropping pump, and the internal temperature of the flask was kept at 85 ° C. with stirring. The raw material pre-emulsion was added dropwise over 4 hours. After completion of the dropwise addition, the polymerization was further allowed to proceed for 1 hour, cooled, and the following sodium hydroxide aqueous solution was added to prepare a polyorganosiloxane copolymer aqueous dispersion (SiEm). The solid content was 18% by mass.
Raw material composition:
3 to 7-mer mixture of cyclic dimethylsiloxane oligomer 98 parts γ-methacryloyloxypropylmethyldimethoxysilane 2 parts deionized water 310 parts sodium dodecylbenzenesulfonate 0.7 part sodium hydroxide aqueous solution:
Sodium hydroxide 1.5 parts Deionized water 30 parts

[Example 1]
The following first raw material mixture was charged into a flask equipped with a stirrer, a reflux condenser, a temperature controller, and a dropping pump. An aqueous reducing agent solution was added. Further, after confirming the peak top temperature due to the polymerization exotherm, the external temperature of the flask was maintained at 75 ° C.

First raw material mixture:
SiEm 5 parts (solid content 0.9 parts)
Radical polymerizable monomer mixture (a)
25 parts of methyl methacrylate
Glycidyl methacrylate 3 parts
2-hydroxyethyl methacrylate 1 part
Triallyl cyanurate 1 part Surfactant Newcor 707SF (trade name, manufactured by Nippon Emulsifier Co., Ltd., solid content 30% by mass) 5 parts (solid content 1.5 parts)
Deionized water 88 parts Initiator Perbutyl H69 (trade name, manufactured by NOF Corporation) 0.02 parts

Basic compounds:
0.01 parts by weight 28% ammonia aqueous solution

Reducing agent aqueous solution:
Ferrous sulfate 0.0002 parts Ethylenediamine (EDTA) 0.0005 parts Sodium ascorbate 0.12 parts Deionized water 6 parts

Then, 0.5 hours after adding the reducing agent aqueous solution, the second raw material mixture (pre-emulsion liquid emulsified and dispersed in advance) and the following aqueous initiator solution were added dropwise over 1.75 hours. During the dropping, the external temperature of the flask was maintained at 75 ° C., and after completion of the dropping, the flask was held at 75 ° C. for 1.5 hours.

Second raw material mixture:
Radical polymerizable monomer mixture (b)
Methyl methacrylate 23.4 parts
Normal butyl methacrylate 23.4 parts
2-ethylhexyl acrylate 17.2 parts
2-hydroxyethyl methacrylate 2 parts
1.5 parts of diacetone acrylamide
Acrylic acid 2.5 parts Surfactant Newcor 707SF 2.5 parts
(Solid content 0.75 part)
Surfmer FP-120 (trade name, Toho Chemical Industry Co., Ltd.,
(Solid content 100% by mass) 0.5 part 28% by mass ammonia aqueous solution 0.17 part deionized water 25 parts

Initiator aqueous solution:
Initiator Perbutyl H69 0.03 parts Deionized water 5 parts

Then, it cooled to room temperature, 28 mass% ammonia water (1.24 parts) was added, the following raw material was added sequentially, and the aqueous coating material was obtained.

Adipic acid dihydrazide aqueous dispersion:
Adipic acid dihydrazide 0.7 parts Deionized water 1.5 parts

[Examples 2 to 4]
An aqueous coating material was obtained in the same manner as in Example 1 except that the amount of the basic compound was changed as shown in Table 1.

[Example 5]
The following first raw material mixture was charged in a flask equipped with a stirrer, a reflux condenser, a temperature controller, and a dropping pump, and after raising the internal temperature of the flask to 52 ° C., the following basic compound was added, and after pH measurement, An aqueous initiator solution and an aqueous reducing agent solution were added. Further, after confirming the peak top temperature due to polymerization exotherm, the internal temperature of the flask was maintained at 70 ° C.

First raw material mixture:
SiEm 4 parts (solid content 0.72 parts)
Radical polymerizable monomer mixture (a)
Methyl methacrylate 40 parts Surfactant ADEKA rear soap SR-1025 (trade name, manufactured by ADEKA Corporation,
(Solid content 25% by mass) 2.12 parts (solid content 0.53 parts)
103 parts deionized water

Basic compounds:
28 parts by mass aqueous ammonia solution 0.1 parts

Initiator aqueous solution:
Ammonium persulfate 0.075 parts Deionized water 1 part

Reducing agent aqueous solution:
Sodium bisulfite 0.025 parts Deionized water 1 part

Then, after 0.75 hours, the second raw material mixture (pre-emulsion liquid emulsified and dispersed in advance) was added dropwise over 1.5 hours. During the dropping, the external temperature of the flask was maintained at 70 ° C., and after completion of the dropping, the flask was held at 70 ° C. for 1.5 hours.

Second raw material mixture:
Radical polymerizable monomer mixture (b)
Methyl methacrylate 28.8 parts
Normal butyl methacrylate 5 parts
2-Ethylhexyl acrylate 25.2 parts
Acrylic acid 1 part Surfactant Adekaria soap SR-1025 1.88 parts (solid content 0.47 parts)
20 parts of deionized water

Then, it cooled to room temperature and added 28 mass% ammonia water (0.74 part), and obtained the aqueous coating material.

表１中の略号は、以下の化合物を示す。また、表１の単位は全て質量部である。
ＭＭＡ ：メチルメタクリレート
ＧＭＡ ：グリシジルメタクリレート
２−ＨＥＭＡ ：２−ヒドロキシエチルメタクリレート
ＴＡＣ ：トリアリルシアヌレート
ｎ−ＢＭＡ ：ノルマルブチルメタクリレート
２−ＥＨＡ ：２―エチルヘキシルアクリレート
ＡＡ ：アクリル酸
ＤＡＡｍ ：ジアセトンアクリルアミド
ニューコール７０７ＳＦ：非反応性アニオン性界面活性剤(商品名、日本乳化剤(株)製)
アデカリアソープＳＲ−１０２５：反応性アニオン性界面活性剤（商品名、ＡＤＥＫＡ（株）製）
サーフマーＦＰ−１２０：リン酸エステル型反応性界面活性剤（商品名、東邦化学工業（株）製）
２８％ＮＨ_３ａｑ：２８質量％アンモニア水溶液

The abbreviations in Table 1 indicate the following compounds. All the units in Table 1 are parts by mass.
MMA: Methyl methacrylate GMA: Glycidyl methacrylate 2-HEMA: 2-Hydroxyethyl methacrylate TAC: Triallyl cyanurate n-BMA: Normal butyl methacrylate 2-EHA: 2-ethylhexyl acrylate AA: Acrylic acid DAAm: Diacetone acrylamide Newcol 707SF : Non-reactive anionic surfactant (trade name, manufactured by Nippon Emulsifier Co., Ltd.)
ADEKA rear soap SR-1025: reactive anionic surfactant (trade name, manufactured by ADEKA Corporation)
Surfmer FP-120: Phosphate ester type reactive surfactant (trade name, manufactured by Toho Chemical Industry Co., Ltd.)
28% NH ₃ aq: 28% by mass ammonia aqueous solution

[Comparative Example 1]
An aqueous coating material was obtained in the same manner as in Example 1 except that the amount of the basic compound was changed as shown in Table 1.

[Comparative Example 2]
An aqueous coating material was obtained in the same manner as in Example 5 except that the amount of the basic compound was changed as shown in Table 1.

Each evaluation result is shown in Table 1.
As shown in Table 1, Examples 1 to 5 of the present invention showed excellent polymerization stability because a basic compound was added before the start of polymerization and emulsion polymerization was started under conditions of pH 9 or higher. . And the coating film obtained using the aqueous coating material of Examples 1-5 showed the outstanding water resistance and weather resistance.

  On the other hand, Comparative Example 1 and Comparative Example 2 did not show an excellent polymerization stability because no basic compound was added before the polymerization was started and emulsion polymerization was started under a pH of less than 9.

  The present invention is a method for producing an emulsion capable of forming a coating film excellent in water resistance and weather resistance with high productivity. Therefore, it can be used for various coating applications such as protection of building bodies, civil engineering structures, and the like, which is extremely useful industrially.

Claims (2)

  A polyorganosiloxane polymer obtained by polymerizing a dimethylsiloxane cyclic oligomer and a grafting agent comprising a hydrolyzable silyl group-containing radical polymerizable monomer and a radical polymerizable monomer mixture (a) are collectively emulsified at a pH of 9 or more. A method for producing an emulsion, wherein after polymerization, a polymer is formed by emulsion polymerization while dropping the radical polymerizable monomer mixture (b).   The method for producing an emulsion according to claim 1, wherein the mass ratio of the radical polymerizable monomer mixture (a) to the radical polymerizable monomer mixture (b) is 25/75 to 80/20.