JP2007056120A - Method for producing aqueous dispersion of resin composition and aqueous dispersion of resin composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a composite resin emulsion scarcely causing phase separation of a resin (C) other than a polyamide resin from a polymer of a radically polymerizable unsaturated monomer (A), having various characteristics possessed by the resin (C) other than the polyamide resin and characteristics such as weather and hydrolytic resistances, high gloss or low cost possessed by especially (meth)acrylic acid derivative polymers in combination. <P>SOLUTION: The method for producing the aqueous dispersion of a resin composition is characterized as follows. The radically polymerizable unsaturated monomer (A) is polymerized in the presence of a basic aqueous dispersion of the resin (C) other than the polyamide resin in an aqueous medium using a cationic radical polymerization initiator (b1) and an amphoteric ionic radical polymerization initiator (b2). <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

The present invention relates to a method for producing an aqueous dispersion of a resin composition. Specifically, the resin composition is in a state where the resin (C) other than the polyamide resin and the acrylic copolymer are in a unified state, and can be called a composite resin.

Conventionally, an attempt has been made to obtain an emulsion in which a polymer composed of an ethylenically unsaturated monomer, in particular, an acrylic copolymer having a (meth) acrylic acid derivative as a main constituent monomer and a resin other than an acrylic resin is combined. It is coming.
Among them, composites that combine the properties of (meth) acrylic acid derivative polymers such as weather resistance, hydrolysis resistance, and low cost with polyurethane resins such as strength, abrasion resistance, and solvent resistance. For the purpose of obtaining a resin, it has been proposed to produce a composite resin emulsion by emulsion polymerization of an ethylenically unsaturated monomer in the presence of a polyurethane emulsion (Patent Documents 1 to 4).
However, in the case of the above production method in which an ethylenically unsaturated monomer is emulsion-polymerized in the presence of polyurethane emulsion, the polymerization stability at the time of emulsion polymerization may be lacking, and the obtained composite resin emulsion has polyurethane and ethylenic properties. The composite with the unsaturated monomer polymer is not closely formed, and the film obtained by drying the composite resin emulsion is inferior in solvent resistance and cold resistance.

In addition, a method for emulsion polymerization of an ethylenically unsaturated monomer in the presence of polyester has been proposed (Patent Document 5), but in this method, a relatively large amount of polyester resin will be combined with the ethylenically unsaturated monomer. In such a case, the polymerization stability is lacking.

In general, aqueous dispersions of various resins are given affinity for water by neutralizing acid groups such as carboxylic acid present in the resin structure with a base such as ammonia or amine. And in order to ensure the stability of those dispersions, the pH of the aqueous dispersion is often made basic exceeding 7. As a result, it is difficult to perform complex radical polymerization with a copolymer composed of radical polymerizable monomers, that is, stable radical polymerization of monomers in the presence of an aqueous dispersion of various resins.
Japanese Patent Application Laid-Open No. 62-241902 JP-A-5-320299 Japanese Patent Laid-Open No. 10-30057 JP 2000-281705 A JP-A-2005-060460

  The object of the present invention is to prevent phase separation between the resin (C) other than the polyamide resin and the polymer of the radical polymerizable unsaturated monomer (A), and a resin other than the polyamide resin such as a polyester resin, a polyurethane resin or a polyolefin resin. To provide an aqueous dispersion of a kind of composite resin having both the characteristics of (C) and particularly the weather resistance, hydrolysis resistance, high gloss and low cost of a (meth) acrylic acid derivative polymer. It is.

  As a result of repeated researches by the present inventors on the above problems, a composite resin emulsion having good polymerization stability and characteristics of each resin can be obtained by using a specific radical polymerizable initiator as an essential component. The present invention has been completed.

That is, in the first invention, the cationic radical polymerization initiator (b1) and the zwitterionic radical polymerization initiator (b2) are added in the presence of the basic aqueous dispersion of the resin (C) other than the polyamide resin. The present invention relates to a method for producing an aqueous dispersion of a resin composition, wherein the radical polymerizable unsaturated monomer (A) is polymerized in an aqueous medium.

In the second invention, the resin (C) other than the polyamide resin is at least one selected from the group consisting of a polyester resin, a polyurethane resin, and a polyolefin resin. The present invention relates to a method for producing an aqueous dispersion of a product.

In the third invention, the ratio of the radical polymerizable unsaturated monomer (A) and the resin (C) other than the polyamide resin is (A) / (C) = 95-5 / 5-95 (weight ratio). It is related with the manufacturing method of the aqueous dispersion of the resin composition of 1st or 2nd invention characterized by these.

Moreover, 4th invention is the total amount of cationic radical polymerization initiator (b1) and zwitterionic radical polymerization initiator (b2) with respect to 100 weight part of radically polymerizable unsaturated monomers (A). The present invention relates to a method for producing an aqueous dispersion of a resin composition according to any one of the first to third inventions, wherein the content is 0.01 to 1 part by weight.

In the fifth invention, the ratio of the cationic radical polymerization initiator (b1) to the zwitterionic radical polymerization initiator (b2) is (b1) / (b2) = 95 to 5/5 to 95. It is related with the manufacturing method of the aqueous dispersion of the resin composition of any one of the 1st thru | or 4th invention characterized by being (weight ratio).

Furthermore, the sixth invention provides a cationic radical polymerization initiator (b1) and a zwitterionic radical polymerization initiator (b2) in the presence of a basic aqueous dispersion of a resin (C) other than a polyamide resin. And an aqueous dispersion of a resin composition obtained by polymerizing the radical polymerizable unsaturated monomer (A) in an aqueous medium.

  According to the present invention, phase separation between the resin (C) other than the polyamide resin such as polyester resin, polyurethane resin, polyolefin resin and the polymer of the radical polymerizable unsaturated monomer (A) hardly occurs, and the polyester resin, polyurethane resin, polyolefin Providing composite resin emulsions that combine the properties of resins (C) other than polyamide resins, such as resins, and especially the weather resistance, hydrolysis resistance, high gloss, and low cost of (meth) acrylic acid derivative polymers. I can do it now.

The present invention is described in detail below.
Examples of the resin (C) other than the polyamide resin used in the present invention include polyester resin, polyurethane resin, polyolefin resin, epoxy resin, rosin ester resin, phenol resin, silicone resin, polyvinyl acetate, and ethylene-vinyl acetate copolymer. , Polyvinyl chloride, polyvinylidene chloride, ethylene- (meth) acrylic acid copolymer, ethylene- (meth) acrylic acid ester-maleic anhydride copolymer, styrene-maleic acid resin, styrene-butadiene resin, butadiene resin, Examples include acrylonitrile-butadiene resin, poly (meth) acrylonitrile resin, (meth) acrylamide resin, chlorinated polyethylene resin, and chlorinated polypropylene resin. Among these, polyester resin, polyurethane resin, and polyolefin resin are preferred. Arbitrariness.
The basic aqueous dispersion of the resin (C) other than the polyamide resin used in the present invention can be obtained by the method exemplified below.

The polyester resin used in the present invention is various known ones and is not particularly limited, but is preferably a copolymer having a melting point of 70 to 200 ° C. obtained by polycondensation reaction of dicarboxylic acid and glycol. Polyester resin.

Examples of the dicarboxylic acid used for producing such a preferable copolyester resin include terephthalic acid, isophthalic acid, orthophthalic acid, 1,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, and diphenic acid. Aromatic dicarboxylic acids, succinic acid, adipic acid, azelaic acid, sebacic acid and dodecanedicarboxylic acid, and other aliphatic dicarboxylic acids, and cyclohexanedicarboxylic acid and other alicyclic dicarboxylic acids. Of these, aromatic dicarboxylic acids, particularly terephthalic acid, isophthalic acid, and orthophthalic acid are preferred from the viewpoint of obtaining a polyester resin having good heat resistance and high tensile strength. Two or more kinds of such dicarboxylic acids may be used in combination.

On the other hand, examples of glycols used for producing the above preferred copolyester resins include ethylene glycol, propylene glycol, 1,3-propanediol, 2,3-butanediol, 1,4-butanediol, , 5-pentanediol, 1,6-hexanediol, neopentyl glycol, aliphatic glycols such as diethylene glycol and dipropylene glycol, 1,4-cyclohexanediol, spiroglycol and alicyclic glycols such as hydrogenated bisphenol A, and Examples include ether bond-containing glycols such as polyethylene glycol and polypropylene glycol. Among these, the adjustment of the melting point of the target polyester resin is easy, and aliphatic glycols, in particular, ethylene glycol, diethylene glycol, polyethylene glycol, 1,3-propanediol, from the viewpoint of obtaining a polyester resin with high tensile strength, 1,4-butanediol and 1,6-hexanediol are preferred. Two or more kinds of such glycols may be used in combination.

Specific examples of the above preferred copolyester resin include terephthalic acid-isophthalic acid-ethylene glycol copolymer polyester resin, terephthalic acid-isophthalic acid-ethylene glycol-1,4-butanediol copolyester resin, terephthalic acid-isophthalate. Acid-1,4-butanediol copolymerized polyester resin, terephthalic acid-isophthalic acid-ethylene glycol-1,3-propanediol-1,4-butanediol copolymerized polyester resin, terephthalic acid-isophthalic acid-1,3- Propanediol-1,4-butanediol copolymerized polyester resin, terephthalic acid-isophthalic acid-ethylene glycol-1,3-propanediol copolymerized polyester resin, and terephthalic acid-isophthalic acid-1,3-propanediol copolymer If polyester resins. Among these, terephthalic acid-isophthalic acid-ethylene glycol-1,4-butanediol copolymer polyester resin, terephthalic acid-isophthalic acid-ethylene glycol copolymer polyester resin, and terephthalic acid-isophthalic acid-1,4-butanediol copolymer Polyester resins are preferred. These polyester resins may be used alone or in a mixture of two or more.

  By dispersing the above polyester resin in an aqueous medium, an aqueous dispersion used in the present invention can be obtained. In order to improve the dispersibility of the resin, the aqueous medium has a weight average molecular weight of 4000 to 30000. It is preferable that an ethylene oxide-propylene oxide copolymer is contained.

Furthermore, it is preferable that a nonionic surfactant is contained for the purpose of further reducing the particle system of the dispersed particles and improving the static stability.
The nonionic surfactant is not particularly limited,
Polyoxyethylene alkyl ethers such as polyoxyethylene decyl ether, polyoxyethylene lauryl ether, polyoxyethylene cetyl ether, polyoxyethylene oleyl ether, polyoxyethylene stearyl ether,
Polyoxyethylene alkyl phenyl ethers such as polyoxyethylene octyl phenyl ether, polyoxyethylene nonyl phenyl ether, polyoxyethylene dodecyl phenyl ether,
Polyoxyethylene sorbitan fatty acid monoesters such as polyoxyethylene sorbitan lauric acid monoester, polyoxyethylene sorbitan stearic acid monoester, polyoxyethylene sorbitan oleic acid monoester, etc. are preferred, and these may be used in combination of two or more. .

As a method of dispersing the polyester resin in the aqueous medium, for example, the following method can be used.
(1) Charge water, a polyester resin and, if necessary, an ethylene oxide-propylene oxide copolymer and a nonionic surfactant into a dispersion tank, raise the temperature to a temperature above which the polyester resin softens, and then mix the polyester by means such as stirring. A method of forcibly dispersing resin.
(2) The dispersion tank is heated and pressurized in advance above the temperature at which the polyester resin softens in the aqueous medium, and while stirring, the molten polyester resin and, if necessary, the molten ethylene oxide-propylene oxide copolymer A method of forcibly dispersing a polyester resin while maintaining the temperature by press-fitting a polymer and water containing a nonionic surfactant as necessary.
(3) The dispersion tank is heated and pressurized in advance above the temperature at which the polyester resin softens in an aqueous medium, and the water containing the melted polyester resin and, if necessary, the ethylene oxide-propylene oxide copolymer is stirred. And a method of forcibly dispersing the polyester resin while maintaining the temperature by injecting water containing a nonionic surfactant as necessary.

In any of the above steps, a basic aqueous dispersion can be obtained by adding a basic compound at an arbitrary point in the dispersion step.

  The weight average particle size of the aqueous polyester resin dispersion is preferably 0.1 to 5 μm, and more preferably 0.5 to 3 μm.

  Examples of the basic aqueous dispersion of the polyester resin that can be used in the present invention include Sephojon ES-900 (pH 9.0) manufactured by Sumitomo Seika Co., Ltd.

Next, an aqueous dispersion of polyurethane resin will be described.
The aqueous dispersion of the polyurethane resin may be any polyurethane-based aqueous dispersion in which the polyurethane-based polymer is stably emulsified and dispersed in the aqueous liquid, and the type of polyurethane in the aqueous dispersion and the production method thereof, The production method of the aqueous dispersion is not particularly limited. The polyurethane-based aqueous dispersion may be, for example, an aqueous dispersion of a self-emulsifying polyurethane having a large number of hydrophilic groups for promoting emulsification in the polyurethane skeleton, or an emulsifier such as a surfactant with a low emulsifying polyurethane. May be a polyurethane-based aqueous dispersion that is forcibly emulsified in an aqueous liquid.

  Among them, in the present invention, an isocyanate-terminated urethane prepolymer (hereinafter simply referred to as “urethane”) obtained by reacting an organic polyisocyanate with a polyol-based compound (polyol-based mixture) mainly composed of a polymer polyol as a polyurethane-based aqueous dispersion. A polyurethane-based aqueous dispersion in which a polyurethane obtained by reacting a chain extender with a prepolymer is sometimes emulsified and dispersed in an aqueous liquid is preferably used. The polyol-based compound used for the production of the urethane prepolymer may be composed of only a high-molecular polyol or a mixture of a high-molecular polyol and a low-molecular compound having two or more isocyanate-reactive groups (polyol mixture). Also good. In the production of a polyurethane-based aqueous dispersion, the urethane prepolymer is emulsified and dispersed in an aqueous liquid in the presence or absence of a surfactant, or after being emulsified and dispersed, and then reacted with a chain extender. it can. At that time, in order to make it easy to emulsify and disperse the urethane prepolymer in the aqueous liquid, the urethane prepolymer is diluted with an organic solvent such as acetone, methyl ethyl ketone, toluene, ethyl acetate, tetrahydrofuran, dimethylformamide and emulsified and dispersed in the aqueous liquid. You may let them. In some cases, part or all of the chain extender may be reacted with a urethane prepolymer to produce a polyurethane, and then the polyurethane may be emulsified and dispersed in an aqueous liquid.

  Examples of the polymer polyol used in the production of the urethane prepolymer for producing the polyurethane-based aqueous dispersion include polyester polyol, polycarbonate polyol, polyester polycarbonate polyol, polyether polyol, and the like. 1 type (s) or 2 or more types can be used. Among these, one or more of polyester polyol, polycarbonate polyol, and polyether polyol are preferably used.

  According to a conventional method, the above-mentioned polyester polyol may be subjected to a direct esterification reaction or a transesterification reaction between a polycarboxylic acid component such as an ester-forming derivative such as polycarboxylic acid, its ester, and an anhydride and a polyol component. Or by ring-opening polymerization of a lactone using a polyol as an initiator.

  As a polycarboxylic acid component that can be used in the production of a polyester polyol for producing a urethane prepolymer, a polycarboxylic acid component generally used in the production of a polyester polyol can be used. For example, succinic acid, glutaric acid, adipic acid , Pimelic acid, suberic acid, azelaic acid, sebacic acid, dodecanedioic acid, 2-methylsuccinic acid, 2-methyladipic acid, 3-methylpentanedioic acid, 2-methyloctanedioic acid, 3,8-dimethyldecanedioic acid Aliphatic dicarboxylic acids such as 3,7-dimethyldecanedioic acid; aromatic dicarboxylic acids such as isophthalic acid, terephthalic acid, phthalic acid and naphthalenedicarboxylic acid; alicyclic dicarboxylic acids such as 1,4-cyclohexanedicarboxylic acid; Tricarboxylic acids such as trimellitic acid and trimesic acid; Etc. can be mentioned Le forming derivatives can be used alone or in combination of two or more thereof. Among them, the polyester polyol is mainly composed of an aliphatic dicarboxylic acid or an ester-forming derivative thereof as a polycarboxylic acid component, and optionally contains a small amount of a tri- or higher functional polycarboxylic acid or an ester-forming derivative thereof. It is preferable that it is manufactured.

As a polyol component that can be used in the production of a polyester polyol for producing a urethane prepolymer, those generally used in the production of a polyester polyol can be used. For example, ethylene glycol, propylene glycol, 2-methyl-1 , 3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, neopentyl glycol, 1,7-heptanediol, 1 , 8-octanediol, 1,9-nonanediol, 2-methyl-1,8-octanediol, 1,10-decanediol and the like; Alicyclic diols such as cyclohexanedimethanol and cyclohexanediol; Glycerin , Trimethylolpropane, Phytantriol, hexane triol, trimethylol butane, trimethylol pentane, may be mentioned tri- or more functional polyols, such as pentaerythritol, may be used alone or two or more of them. Among them, the polyester polyol is preferably made of an aliphatic diol as a polyol component, and optionally produced using a polyol component containing a small amount of a tri- or higher functional polyol.

  As said lactone which can be used for manufacture of the polyester polyol for urethane prepolymer manufacture, (epsilon) -caprolactone, (beta) -methyl-delta-valerolactone, etc. can be mentioned.

  Examples of the polycarbonate polyol that can be used in the production of the urethane prepolymer include those obtained by a reaction between a polyol and a carbonate compound such as dialkyl carbonate, alkylene carbonate, and diaryl carbonate. As a polyol which comprises a polycarbonate polyol, the polyol illustrated previously as a structural component of a polyester polyol can be used. Examples of the dialkyl carbonate include dimethyl carbonate and diethyl carbonate, examples of the alkylene carbonate include ethylene carbonate, and examples of the diaryl carbonate include diphenyl carbonate.

  Examples of the polyester polycarbonate polyol that can be used for the production of the urethane prepolymer include those obtained by reacting polyol, polycarboxylic acid and carbonate compound simultaneously, and those obtained by reacting polyester polyol and carbonate compound prepared in advance. And a product obtained by reacting a previously produced polycarbonate polyol with a polyol and a polycarboxylic acid, a product obtained by reacting a previously produced polyester polyol and polycarbonate polyol, etc. be able to.

  Examples of the polyether polyol that can be used in the production of the urethane prepolymer include polyethylene glycol, polypropylene glycol, polytetramethylene glycol, and the like, and one or more of these can be used.

  The polymer polyol used for the production of the urethane prepolymer preferably has a number average molecular weight of 500 to 10,000, more preferably 700 to 5,000, from the viewpoint of ease of production, and 750. More preferably, it is ˜4,000. The polymer polyol used for the production of the urethane prepolymer preferably has a hydroxyl group number f per molecule in the range of 1.0 ≦ f ≦ 4.0, and 2.0 ≦ f ≦ 3.0. It is more preferable to be within the range.

  As the organic polyisocyanate used for the production of the urethane prepolymer, any of the organic polyisocyanates conventionally used for the production of polyurethane-based aqueous dispersions can be used, but alicyclic diisocyanates having a molecular weight of 500 or less, aliphatics One or more of diisocyanates and aromatic diisocyanates are preferably used. Examples of such organic diisocyanates include hexamethylene diisocyanate, isophorone diisocyanate, 4,4′-dicyclohexylmethane diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 4,4′-diphenylmethane diisocyanate, Examples include p-phenylene diisocyanate, xylylene diisocyanate, 1,5-naphthylene diisocyanate, and one or more of them can be used.

  As the chain extender to be reacted with the urethane prepolymer, any of chain extenders conventionally used in the production of polyurethane-based aqueous dispersions can be used, but an isocyanate group and a reactive active hydrogen atom in the molecule can be used. A low molecular weight compound having a molecular weight of 300 or less and having two or more is preferably used. Specific examples of the chain extender preferably used include hydrazine, ethylenediamine, propylenediamine, hexamethylenediamine, nonamethylenediamine, xylylenediamine, isophoronediamine, piperazine and derivatives thereof, phenylenediamine, tolylenediamine, xylenediamine, and adipine. Diamines such as acid dihydrazide and isophthalic acid dihydrazide; Triamines such as diethylenetriamine; ethylene glycol, propylene glycol, 1,4-butanediol, 1,6-hexanediol, 1,4-bis (β-hydroxyethoxy) benzene, Diols such as 1,4-cyclohexanediol, bis (β-hydroxyethyl) terephthalate, xylylene glycol; Triols such as trimethylolpropane; Examples include pentaols such as antaerythritol; amino alcohols such as aminoethyl alcohol and aminopropyl alcohol, and one or more of these can be used.

  The amount of the chain extender used is such that the molar ratio of [isocyanate group in the prepolymer]: [isocyanate group in the chain extender and reactive active hydrogen atom] is in the range of 1: 0.5-2. The amount is preferably in the range of 1: 0.7 to 1.5. Further, when the chain extender is reacted with the urethane prepolymer, the chain extender may be reacted with the urethane prepolymer as it is, but the chain extender is dissolved in water or water and a hydrophilic organic solvent. Is preferably used by dissolving in a solvent mixture with the aqueous dispersion of urethane prepolymer, in which case the reaction between the urethane prepolymer and the chain extender proceeds favorably and the polyurethane-based aqueous dispersion Can be manufactured smoothly.

  In the present invention, the polyurethane-based aqueous dispersion has a neutralized carboxyl group and / or neutralized sulfonic acid group in a ratio of 3 to 30 mmol per 100 g of polyurethane in the polyurethane skeleton, and the pH exceeds 7. A polyurethane-based aqueous dispersion made basic is preferably used because it is excellent in stability during emulsion polymerization of the radically polymerizable unsaturated monomer (A). The polyurethane-based aqueous dispersion having a neutralized carboxyl group and / or sulfonic acid group in the polyurethane skeleton in the above-described proportion is, for example, (i) (a) mainly composed of a polymer polyol, and containing a carboxyl group and / or Whether to produce a urethane prepolymer having a carboxyl group and / or a sulfonic acid group in the skeleton by reacting an organic polyisocyanate with a polyol mixture containing a compound having a sulfonic acid group and having at least one isocyanate-reactive group Or (b) after producing a urethane prepolymer having a carboxyl group and / or a sulfonic acid group in the skeleton by reacting an organic polyisocyanate with a polymer polyol having a carboxyl group and / or a sulfonic acid group in the molecular skeleton. (Ii) the urethane pre-form obtained thereby The carboxyl group and / or sulfonic acid group in the limer is neutralized with a basic compound such as a tertiary amine such as triethylamine or trimethylamine, an alkali metal hydroxide such as sodium hydroxide or potassium hydroxide, and then ( iii) The neutralized urethane prepolymer can be produced by emulsifying it in an aqueous liquid and then reacting with a chain extender.

  Examples of the compound having a carboxyl group and / or sulfonic acid group in the skeleton used in the step (i) (a) and having at least one isocyanate-reactive group include 2,2-bis (hydroxymethyl). ) Carboxyl group-containing compounds such as propionic acid, 2,2-bis (hydroxymethyl) butyric acid, 2,2-bis (hydroxymethyl) valeric acid and their derivatives; 1,3-phenylenediamine-4,6-disulfonic acid And sulfonic acid group-containing compounds such as 2,4-diaminotoluene-5-sulfonic acid, and the like, and one or more of these can be used. Examples of the polymer polyol having a carboxyl group and / or a sulfonic acid group in the molecular skeleton used in (b) of the above step (i) include, for example, a polyol component that is reacted with a polycarboxylic acid component during the production of a polyester polyol. As a part, using a carboxyl group-containing polyol such as 2,2-bis (hydroxymethyl) propionic acid, 2,2-bis (hydroxymethyl) butyric acid, 2,2-bis (hydroxymethyl) valeric acid or a derivative thereof The manufactured polyester polyol etc. can be mentioned.

  In addition, the polyurethane-based aqueous dispersion used in the present invention has the above-described properties (that is, a point having 3 to 30 mmol of neutralized carboxyl groups and / or sulfonic acid groups per 100 g of polyurethane in the polyurethane skeleton), It is preferable that the surfactant is contained at a ratio of 0.5 to 10 g per 100 g of polyurethane in the aqueous dispersion. In that case, the radically polymerizable unsaturated monomer (A) can be stably emulsion-polymerized in the presence of the polyurethane-based aqueous dispersion, and the performance of the resulting composite resin is improved. Examples of the surfactant used in the polyurethane-based aqueous dispersion include sodium lauryl sulfate, ammonium lauryl sulfate, polyoxyethylene tridecyl ether sodium acetate, sodium dodecylbenzene sulfonate, sodium alkyldiphenyl ether disulfonate, di (2-ethylhexyl). Anionic surfactants such as sodium sulfosuccinate; such as polyoxyethylene nonylphenyl ether, polyoxyethylene octylphenyl ether, polyoxyethylene lauryl ether, polyoxyethylene stearyl ether, polyoxyethylene-polyoxypropylene block copolymer Nonionic surfactant etc. can be mentioned, These 1 type (s) or 2 or more types can be used. Among them, it is preferable from the viewpoint of polymerization stability when the radical polymerizable unsaturated monomer (A) is emulsion-polymerized that at least a part of the surfactant is an anionic surfactant. More preferably, it is an anionic surfactant. In particular, one or more of sodium lauryl sulfate, ammonium lauryl sulfate, and sodium polyoxyethylene tridecyl ether acetate are more preferable.

In the polyurethane-based aqueous dispersion, the average particle size of the particles contained in the emulsion is 500 nm or less when measured by the dynamic light scattering method and analyzed by the cumulant method. From the viewpoint of production stability, etc., it is preferably 400 nm or less, more preferably 300 nm or less. When the average particle size of the particles in the polyurethane-based aqueous dispersion exceeds 500 nm, gelation of the system occurs during the emulsion polymerization of the radically polymerizable unsaturated monomer (A) in the presence of the polyurethane-based aqueous dispersion. It becomes easy.

  Basic aqueous dispersions of polyester resin used in the present invention include Dispacol U-53 (pH 7.5) manufactured by Sumika Bayer Urethane Co., Ltd., HD-8208 (pH 8.0) manufactured by Hauthaway, and HD-8209. (PH 8.0), HD-8217 (pH 8.0), HD-8261 (pH 9.0), HD-8284 (pH 8.0), HD-8308 (pH 7.5), HD-8507 (pH 8.0) , HD-8509 (pH 8.0), HD-8510 (pH 8.0), HD-8518 (pH 9.0), HD-8533 (pH 8.0), HD-8588 (pH 9.0), HD-8615 ( pH 8.0), HD-8635 (pH 8.0), HD-8690 (pH 8.0), and the like.

Next, the aqueous dispersion of polyolefin resin will be described.
The polyolefin resin contains 50 to 98 mass%, preferably 60 to 98 mass%, more preferably 70 to 98 mass%, particularly preferably 75 to 95 mass% of unsaturated hydrocarbons having 3 to 6 carbon atoms as monomer units. It is a polyolefin resin of mass%. When the content of unsaturated hydrocarbons having 3 to 6 carbon atoms is less than 50% by mass, the adhesiveness to polyolefin materials such as polypropylene is lowered, and when it exceeds 98% by mass, the content of unsaturated carboxylic acid units described later is relatively included. Since the amount decreases, it becomes difficult to make the resin water-based. Examples of unsaturated hydrocarbons having 3 to 6 carbon atoms include alkenes such as propylene, 1-butene, isobutene, 1-pentene, 4-methyl-1-pentene, 3-methyl-1-pentene, 1-hexene, and butadiene And dienes such as isoprene, propylene component or butene component (1-butene, isobutene, etc.) from the viewpoint of ease of resin production, ease of aqueous formation, adhesion to various materials, blocking properties, etc. ) Is preferable, and both may be used in combination. The polyolefin resin used in the present invention preferably further contains 2 to 50% by mass of an ethylene component in addition to the above-mentioned unsaturated hydrocarbon having 3 to 6 carbon atoms. By containing an ethylene component, water-based resin and film performance are improved.

  A particularly preferred configuration for the polyolefin resin used in the present invention is one containing three components of a propylene component, a butene component, and an ethylene component as monomer units, and the composition ratio is such that the sum of these three components is 100 parts by mass. 8 to 90 parts by mass of a propylene component, 8 to 90 parts by mass of a butene component, and 2 to 50 parts by mass of an ethylene component.

  In the above-mentioned polyolefin resin, the copolymerization form of each component is not limited, and examples thereof include random copolymerization and block copolymerization. From the viewpoint of ease of polymerization, random copolymerization is preferable. Moreover, you may mix 2 or more types of polyolefin resin so that it may become the structural component ratio of this invention.

  The acid value of the polyolefin resin can be imparted by introducing an unsaturated carboxylic acid unit. The unsaturated carboxylic acid unit is introduced by an unsaturated carboxylic acid or its anhydride. Specific examples include acrylic acid, methacrylic acid, maleic acid, maleic anhydride, itaconic acid, itaconic anhydride, aconitic acid, and aconitic anhydride. In addition to acids, fumaric acid, crotonic acid, citraconic acid, mesaconic acid, allyl succinic acid, etc., at least one carboxyl group in the molecule (in the monomer unit) such as unsaturated dicarboxylic acid half ester, half amide, etc. A compound having an acid anhydride group can be used. Of these, maleic anhydride, acrylic acid, and methacrylic acid are preferred, and maleic anhydride is more preferred from the viewpoint of ease of introduction into the polyolefin resin. The unsaturated carboxylic acid unit may be copolymerized in the polyolefin resin, and the form thereof is not limited, and examples thereof include random copolymerization, block copolymerization, and graft copolymerization. Incidentally, the acid anhydride unit introduced into the polyolefin resin tends to take an acid anhydride structure in a dry state, and in the aqueous medium containing the basic compound, part or all of the acid anhydride units are opened to form a carboxylic acid or It tends to be the salt structure.

  The unsaturated carboxylic acid only needs to be copolymerized in the polyolefin resin, and the form thereof is not limited, and examples thereof include random copolymerization, block copolymerization, and graft copolymerization. For example, in the case of graft copolymerization, for example, a method in which a polyolefin resin and an unsaturated carboxylic acid are heated and melted to a temperature equal to or higher than the melting point of the polyolefin resin in the presence of a radical generator, or after the polyolefin resin is dissolved in an organic solvent. Examples thereof include a method of graft copolymerizing an unsaturated carboxylic acid unit on a polyolefin resin by a method of heating and stirring in the presence of a radical generator. Examples of the radical generator used for graft copolymerization include di-tert-butyl peroxide, dicumyl peroxide, tert-butyl hydroperoxide, tert-butyl cumyl peroxide, benzoyl peroxide, dilauryl peroxide, Examples thereof include organic peroxides such as cumene hydroperoxide, tert-butyl peroxybenzoate, ethyl ethyl ketone peroxide, and di-tert-butyl diperphthalate, and azonitriles such as azobisisobutyronitrile. These may be appropriately selected and used depending on the reaction temperature.

  The weight average molecular weight of the polyolefin resin is preferably 5,000 to 150,000, more preferably 20,000 to 120,000, still more preferably 30,000 to 100,000, It is particularly preferably from 000 to 90,000, most preferably from 40,000 to 80,000. When the weight average molecular weight is less than 5,000, there is a tendency that the adhesion to the substrate is lowered or the resulting coating film is hard and brittle. When the weight average molecular weight exceeds 150,000, it tends to be difficult to make the resin water-based. In addition, the weight average molecular weight of resin can be calculated | required on the basis of polystyrene resin using a gel permeation chromatography (GPC).

  In the aqueous dispersion of the present invention, the polyolefin resin is dispersed or dissolved in an aqueous medium. The number average particle diameter of the polyolefin resin particles dispersed in the aqueous dispersion is 1 μm or less. Further, from the viewpoint of low-temperature film-forming properties, it is preferably 0.5 μm or less, more preferably 0.3 μm or less, and further preferably 0.2 μm or less. When the number average particle diameter exceeds 1 μm, the low-temperature film-forming property is remarkably deteriorated, and the storage stability of the aqueous dispersion is lowered. The volume average particle diameter is also preferably 2 μm or less, more preferably 1 μm or less, further preferably 0.5 μm or less, and particularly preferably 0.3 μm or less from the viewpoint of low-temperature film-forming properties and storage stability. A preferable lower limit of the number average particle size and the volume average particle size is 0.01 μm. When the particle diameter is less than 0.01 μm, the viscosity may increase when the solid content concentration of the aqueous dispersion is increased.

  The aqueous dispersion of the present invention needs to contain a basic compound. The basic compound neutralizes the carboxyl group in the polyolefin resin, and the carboxyl anion generated by the neutralization prevents aggregation between the resin fine particles by its electric repulsive force, and the pH of the aqueous dispersion exceeds 7 This imparts stability to the aqueous dispersion. The basic compound contained in the aqueous dispersion may be any compound that can neutralize the carboxyl group. In order not to impair the effects of the present invention, it is preferable to use a basic compound that is volatile (for example, a boiling point of 300 ° C. or lower).

  As the basic compound, ammonia that volatilizes during film formation or an organic amine compound having a boiling point of 30 to 250 ° C. is preferable from the viewpoint of water resistance of the film, and an organic amine compound of 50 to 200 ° C. is more preferable.

  Specific examples of the organic amine compound include triethylamine, N, N-dimethylethanolamine, isopropylamine, aminoethanol, dimethylaminoethanol, diethylaminoethanol, ethylamine, diethylamine, isobutylamine, dipropylamine, 3-ethoxypropylamine, 3 -Diethylaminopropylamine, sec-butylamine, propylamine, n-butylamine, 2-methoxyethylamine, 3-methoxypropylamine, 2,2-dimethoxyethylamine, monoethanolamine, morpholine, N-methylmorpholine, N-ethylmorpholine, Examples include pyrrole and pyridine.

In the production of the aqueous dispersion of the present invention, as described later, it is necessary to use a non-volatile aqueous additive or an organic solvent in order to promote the aqueous formation of the polyolefin resin and reduce the dispersed particle size. As such, the resulting aqueous dispersion may contain these. The non-volatile aqueous auxiliary agent and the organic solvent may be used in combination.
“Aqueous aid” refers to a drug or compound added for the purpose of promoting aqueousization or stabilizing the aqueous dispersion in the production of an aqueous dispersion. It means that it does not have a boiling point at pressure, or has a high boiling point (eg, 300 ° C. or higher) at normal pressure.

  On the other hand, when an organic solvent is used during the production of the aqueous dispersion, it is not always necessary to use a non-volatile aqueous solubilizing aid, so that an aqueous dispersion substantially free of non-volatile aqueous solubilizing aid is produced. be able to. Further, if the organic solvent used is volatile (for example, boiling point less than 300 ° C.), even if it is contained in the aqueous dispersion, it does not remain in the film at the time of use. Further, as described later, by performing a stripping operation in a part of the production process, substantially all of the organic solvent used can be removed to obtain an aqueous dispersion containing no organic solvent.

  Examples of the non-volatile aqueous additive used in the present invention include surfactants described later, compounds having a protective colloid effect, modified waxes, acid-modified compounds having a high acid value, and water-soluble polymers.

  Examples of the surfactant include a cationic surfactant, an anionic surfactant, a nonionic (nonionic) surfactant, an amphoteric surfactant, a fluorosurfactant, and a reactive surfactant.

  Compounds having protective colloid action, modified waxes, high acid value acid-modified compounds, water-soluble polymers include polyvinyl alcohol, carboxyl group-modified polyvinyl alcohol, carboxymethyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, modified starch, polyvinyl Pyrrolidone, polyacrylic acid and salts thereof, carboxyl group-containing polyethylene wax, carboxyl group-containing polypropylene wax, carboxyl group-containing polyethylene-propylene wax, and other acid-modified polyolefin waxes having a weight average molecular weight of usually 5,000 or less and salts thereof, Acrylic acid-maleic anhydride copolymer and salts thereof, styrene- (meth) acrylic acid copolymer, ethylene- (meth) acrylic acid copolymer, isobutylene-anhydrous A carboxyl group-containing polymer having an unsaturated carboxylic acid content of 17% by mass or more, such as an alternating carboxylic acid copolymer, (meth) acrylic acid- (meth) acrylic acid ester copolymer, polyitaconic acid and its salt, Examples thereof include water-soluble acrylic copolymers having amino groups, gelatin, gum arabic, and casein, which are generally used as fine particle dispersion stabilizers.

  The organic solvent preferably has a boiling point of 250 ° C. or less, more preferably 50 to 200 ° C., and particularly preferably 50 to 185 ° C. in view of easy removal from the coating film. An organic solvent having a boiling point exceeding 250 ° C. is difficult to be scattered from the resin coating film by drying, and the water resistance of the coating film at low temperature drying, adhesion to the substrate, etc. may be deteriorated. Specific examples of the organic solvent used include, for example, methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, sec-butanol, tert-butanol, n-amyl alcohol, isoamyl alcohol, sec-amyl alcohol. , Alcohols such as tert-amyl alcohol, 1-ethyl-1-propanol, 2-methyl-1-butanol, n-hexanol, cyclohexanol, ketones such as methyl ethyl ketone, methyl isobutyl ketone, ethyl butyl ketone, cyclohexanone, tetrahydrofuran , Ethers such as dioxane, ethyl acetate, n-propyl acetate, isopropyl acetate, n-butyl acetate, isobutyl acetate, sec-butyl acetate, 3-methoxybutyl acetate, propylene Esters such as methyl acetate, ethyl propionate, diethyl carbonate, dimethyl carbonate, glycol derivatives such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monopropyl ether, ethylene glycol monobutyl ether, ethylene glycol ethyl ether acetate, Diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, diethylene glycol ethyl ether acetate, 1-methoxy-2-propanol, 1-ethoxy-2-propanol, 3-methoxy-3-methyl-1-butanol, methoxybutanol, acetonitrile , Dimethylformamide, dimethylacetamide, diacetone alcohol Ethyl acetoacetate, 1,2-dimethyl glycerin, 1,3-dimethyl glycerin, trimethyl glycerin. These organic solvents may be used in combination of two or more.

  Among the above organic solvents, ethanol, n-propanol, isopropanol, n-butanol, methyl ethyl ketone, cyclohexanone, tetrahydrofuran, dioxane, ethylene glycol monoethyl ether, ethylene glycol monopropyl are effective because they are highly effective in promoting aqueous formation of resins. Ether, ethylene glycol monobutyl ether, and diethylene glycol monomethyl ether are preferable, and among these, an organic solvent having one hydroxyl group in the molecule is more preferable. Among these, ethylene glycol alkyl ethers are more preferable from the viewpoint that the resin can be made aqueous with a small amount of addition, and n-propanol and isopropanol are more preferable from the viewpoint of easy stripping described later.

  When the above organic solvent is used in the production of the aqueous dispersion, after the resin is made aqueous, a part thereof is distilled out of the system by a solvent removal process generally called “stripping”, and the amount of the organic solvent Can be reduced. By stripping, the content of the organic solvent in the aqueous dispersion can be made 10% by mass or less, and if it is 5% by mass or less, it is environmentally preferable.

  Examples of the stripping method include a method in which the aqueous dispersion is heated with stirring at normal pressure or reduced pressure to distill off the organic solvent. Further, since the solid content concentration is increased by distilling off the aqueous medium, for example, when the viscosity increases and the workability deteriorates, water is added to the aqueous dispersion in advance. Also good.

  Next, the manufacturing method of the polyolefin resin aqueous dispersion is demonstrated.

In order to obtain the aqueous polyolefin resin dispersion, it is necessary to use a nonvolatile aqueous auxiliary agent and / or an organic solvent in addition to the components described above, that is, the polyolefin resin, the basic compound, and the aqueous medium. The aqueous dispersion of the present invention can be obtained by heating and stirring these in a sealable container.

  As the container, an apparatus widely known to those skilled in the art as a solid / liquid stirring apparatus or an emulsifier can be used, and an apparatus capable of pressurization of 0.1 MPa or more is preferably used. The stirring method and the rotation speed of the stirring are not particularly limited, but may be stirring at a low speed such that the resin is in a floating state in the aqueous medium. Therefore, high-speed stirring (for example, 1,000 rpm or more) is not essential, and an aqueous dispersion can be produced with a simple apparatus.

  The raw materials are charged into the above apparatus, and are preferably stirred and mixed at a temperature of 40 ° C. or lower. Next, while maintaining the temperature in the tank at 60 to 220 ° C., preferably 80 to 200 ° C., more preferably 100 to 190 ° C., particularly preferably 100 to 180 ° C., preferably until coarse particles disappear (for example, The aqueous dispersion can be obtained by making the polyolefin resin sufficiently aqueous by continuing stirring for 5 to 120 minutes, and then preferably cooling to 40 ° C. or lower with stirring. When the temperature in the tank is lower than 60 ° C., it becomes difficult to make the polyolefin resin aqueous. When the temperature in a tank exceeds 220 degreeC, there exists a possibility that the molecular weight of polyolefin resin may fall.

  Examples of the method for adjusting the solid content concentration of the aqueous dispersion thus obtained include a method in which the aqueous medium is distilled off or diluted with water so as to obtain a desired solid content concentration.

Examples of the aqueous dispersion of polyolefin resin used in the present invention include Chuo Rika Kogyo Co., Ltd. Aquatex HA-1100, Mitsui Chemicals Chemipearl M-200 (pH 9.0) V-100 (pH 8.0), V- 200 (pH 8.0), V-300 (pH 8.0), W-100 (pH 9.0), W-200 (pH 9.0), W-300 (pH 9.0), W-400 (pH 9.0) ), W-500 (pH 9.0), manufactured by Sumitomo Seika Co., Ltd., Zyxen-A (pH 8.0), Zyxen-AC (pH 8.0), and the like.

  The basic aqueous dispersion of the resin (C) other than the polyamide resin used in the present invention can maintain good dispersion stability when the pH exceeds 7.0, and the dispersion stability is poor at pH 7.0 or less. The resin tends to settle and agglomerate. Accordingly, the pH of the basic aqueous dispersion of the resin (C) other than the polyamide resin is preferably higher than 7.0, and more preferably 7.5 to 11.0.

  The ratio of the radically polymerizable unsaturated monomer (A) used in the present invention and the resin (C) other than the polyamide resin is preferably (A) / (C) = 95-5 / 5-95 (weight ratio). More preferably, it is 90-10 / 10-90, More preferably, it is 80-20 / 20-80. When the proportion of the radically polymerizable unsaturated monomer (A) or the resin (C) other than the polyamide resin is 5% or less, the characteristics as a composite resin utilizing each of them cannot be obtained.

Next, the polymerization initiator used when the polymer of the radical polymerizable monomer (A) and the resin (C) other than the polyamide resin are combined, that is, when the radical polymerizable monomer (A) is polymerized in an aqueous medium. explain.
Examples of the polymerization initiator include water-soluble polymerization initiators, and those having the ability to initiate radical polymerization include azo-based initiators and peroxide-based initiators.
Peroxide-based polymerization initiators such as ammonium persulfate and potassium persulfate are generally used in emulsion polymerization. However, if these peroxide polymerization initiators are used, the pH during emulsion polymerization becomes 2.0 to 3.0, so that the dispersion stability of the resin (C) other than the polyamide resin is impaired during the polymerization. Aggregates during the polymerization and a stable aqueous dispersion cannot be obtained.
Therefore, in the present invention, it is necessary to use an azo initiator. In the present invention, among the azo initiators, the cationic radical polymerization initiator (b1) and the zwitterionic radical polymerization start. It is further necessary from the viewpoint of polymerization stability to use the agent (b2) in combination.

Here, “cationic” refers to the property that only a cationic moiety can be formed in the molecular structure in water (for example, having an amino group in the molecule).
In addition, “zwitterionic” refers to a property in which both a cation moiety and an anion moiety can be formed in the molecular structure in water (for example, both carboxylic acid groups and amino groups are represented by amino acids. Etc.).

  In the present invention, examples of the cationic radical polymerization initiator (b1) include 2,2′-azobis (2-amidinopropane) dihydrochloride (V-50, manufactured by Wako Pure Chemical Industries), 2,2′-azobis. [2- (2-imidazolin-2-yl) propane] dihydrochloride (VA-044, manufactured by Wako Pure Chemical Industries), 2,2′-azobis [2- (2-imidazolin-2-yl) propane] disulfate dihydrate ( VA-046B, manufactured by Wako Pure Chemical Industries, Ltd.), 2,2′-azobis [2- [1- (2-hydroxyethyl) -2-imidazolin-2-yl] propane] dihydrochloride (VA-060, manufactured by Wako Pure Chemical Industries, Ltd.) ), 2,2′-azobis [2- (2-imidazolin-2-yl) propane] (VA-061, Wako Pure Chemical Industries, Ltd.), 2,2′-azobis (1-imino-1-pyrrolodilino-2- Ethyl propa ) Dihydrochloride (VA-067, can be preferably used a water-soluble polymerization initiator such as manufactured by Wako Pure Chemical).

In the present invention, examples of the zwitterionic radical polymerization initiator (b2) include 2,2′-azobis [N- (2-carboxyethyl) -2-methylpropionamidine] hydrate (VA-057, sum) Water-soluble polymerization initiators such as those manufactured by Kojunpaku) can be suitably used.
It is not preferable to use these water-soluble polymerization initiators alone as thermal decomposition polymerization initiators because a stable aqueous dispersion cannot be obtained, and it is necessary to use cationic and zwitterionic radical polymerization initiators in combination. There is.

The ratio of the cationic radical polymerization initiator (b1) to the zwitterionic radical polymerization initiator (b2) is preferably (b1) / (b2) = 95-5 / 5-95 (weight ratio), more preferably Is 80-20 / 20-80, more preferably 60-40 / 40-60.
The total amount of the cationic radical polymerization initiator (b1) and the zwitterionic radical polymerization initiator (b2) is 1 part by weight with respect to 100 parts by weight of the total radical polymerizable unsaturated monomer (A). It is preferable to use below, and it is more preferable to use an amount of about 0.01 to 1 part by weight. When the total amount of both initiators is more than 1 part by weight, the hot water resistance of the film formed from the aqueous dispersion of the resulting resin composition tends to decrease, and the film tends to whiten, which is not preferable. On the other hand, if the total amount of both initiators is less than 0.01 parts by weight, the reaction may not be completed and unreacted monomers may remain.

In the present invention, when performing emulsion polymerization, the azo-based both polymerization initiators can be used as an oxidizing agent, and a reducing agent can be used in combination with them as a redox-based polymerization. Thereby, it becomes easy to accelerate the emulsion polymerization rate or to carry out emulsion polymerization at a low temperature.
Examples of the reducing agent used in the redox polymerization include reducing organic compounds such as metal salts such as ascorbic acid, tartaric acid, citric acid, glucose, formaldehyde sulfoxylate, sodium thiosulfate, sodium sulfite, and bisulfite. Examples thereof include reducing inorganic compounds such as sodium and sodium metabisulfite, ferrous chloride, Rongalite, and thiourea dioxide.
The oxidizing agent and reducing agent are preferably used in amounts of about 0.01 to 1 part by weight and about 0.01 to 2 parts by weight, respectively, with respect to 100 parts by weight of the total radical polymerizable unsaturated monomer (A). In the case of redox polymerization, since a higher molecular weight composite resin is formed as compared with the case where only the azo initiator is used, it is preferable in terms of heat resistance and water resistance.

The polymerization temperature varies depending on the polymerization initiator to be used. For example, in 2,2′-azobis (2-amidinopropane) dihydrochloride (V-50, manufactured by Wako Pure Chemical Industries), it may be usually about 60 ° C. The polymerization time is not particularly limited, but is usually 2 to 24 hours.
Moreover, it is preferable that pH is 8.0 or more during superposition | polymerization and after superposition | polymerization from a viewpoint of stability at the time of superposition | polymerization and dispersion stability, and it is more preferable that it is 8.5-12.0.

  The radical polymerizable unsaturated monomer (A) used in the present invention is selected from one or more of acrylic acid, methacrylic acid or their alkyl esters or derivatives and vinyl monomers known in the art. can do. More specifically, it can be exemplified as follows.

  Examples of the ethylenically unsaturated carboxylic acid include (meth) acrylic acid, itaconic acid, fumaric acid, maleic acid, crotonic acid and the like.

  Examples of the aromatic vinyl compound include styrene, α-methylstyrene, vinyltoluene and the like.

Examples of the ethylenically unsaturated carboxylic acid alkylamide include aminoethylacrylamide, dimethylaminomethylmethacrylamide, methylaminopropylmethacrylamide, aminoalkylamide, (meth) acrylamide, N-methylolacrylamide and the like.
Examples of the ethylenically unsaturated carboxylic acid aminoalkyl ester include aminoethyl acrylate, dimethylaminoethyl (meth) acrylate, diethylaminoethyl (meth) acrylate, butylaminoethyl acrylate, and the like.

  Examples of unsaturated aliphatic glycidyl esters and ethers include glycidyl (meth) acrylate, 3,4-epoxycyclohexylmethyl (meth) acrylate, glycidyl vinyl ether, 3,4-epoxycyclohexyl vinyl ether, glycidyl (meth) allyl ether, 3,4 -Epoxycyclohexyl (meth) allyl ether and the like can be mentioned as examples.

  Examples of the hydroxyl group-containing carboxylic acid ester include hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, hydroxybutyl (meth) acrylate, and the like.

  (Meth) acrylic acid esters include methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, (meth ) Tert-butyl acrylate, octyl (meth) acrylate, isooctyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, lauryl (meth) acrylate, stearyl (meth) acrylate, isodecyl (meth) acrylate , Tridecyl (meth) acrylate, alkylene glycol (meth) alkylate, tetrahydrofurfuryl (meth) acrylate, phenoxyethyl (meth) acrylate, isobornyl (meth) acrylate, tert-amyl (meth) acrylate, ( Meth-acrylic acid tert-butylaminoethyl, (meth) ) Tert-butylethyl acrylate, tert-butylacetyl (meth) acrylate, tert-butyldimethylsilyl (meth) acrylate, tert-amylcyclohexyl (meth) acrylate, tert-butylphenyl (meth) acrylate, (meth An example is tert-butylbenzyl acrylate.

  Further, vinyl cyanide monomers such as (meth) acrylonitrile and α-chloroacrylonitrile can also be used.

In the present invention, a radically polymerizable unsaturated monomer having an alkoxysilyl group can also be used in the polymerization in order to improve the solvent resistance by introducing a crosslinked structure into the dispersion particles.
Specific examples of the polymerizable monomer having an alkoxysilyl group include vinyltrimethoxysilane, γ- (meth) acryloxypropyltrimethoxysilane, allyltriethoxysilane, trimethoxysilylpropylallylamine, vinyltriethoxysilane, vinyltris (β -Methoxyethoxy) silane, γ- (meth) acryloxypropyltriethoxysilane, and the like. These may use only 1 type and may use 2 or more types together suitably.

  The content of the polymerizable monomer having an alkoxysilyl group is 0.05 to 5% by weight, preferably 0, in 100% by weight of the total of monomers to be polymerized, that is, the total of the radical polymerizable unsaturated monomer (A). 0.1 to 3% by weight. If the content of the polymerizable monomer having an alkoxysilyl group is less than 0.05% by weight, the effect of crosslinking hardly appears. On the other hand, if the content exceeds 5% by weight, the coating tends to become brittle, and physical properties during storage Is not preferable because it is likely to change.

  Multifunctional such as divinylbenzene, diallyl phthalate, ethylene dimethacrylate, neopentyl glycol dimethacrylate, triallyl isocyanurate in order to improve the solvent resistance by introducing a crosslinked structure in the same manner as the polymerizable monomer having an alkoxysilyl group. Vinyl monomers and polyfunctional allyl monomers can be used.

  The content of the polyfunctional vinyl monomer and the polyfunctional allyl monomer is 0.05 to 5% by weight, preferably 100% by weight of the total of the monomers to be polymerized, that is, the total of the radical polymerizable unsaturated monomer (A), preferably It is good that it is 0.1 to 3% by weight. When the content of the polyfunctional vinyl monomer and the polyfunctional allyl monomer is less than 0.05% by weight, the effect of crosslinking hardly appears, whereas when the content exceeds 5% by weight, the coating film tends to become brittle and during storage. This is not preferable because the physical properties easily change.

  One or more kinds of these radically polymerizable unsaturated monomers (A) may be arbitrarily used as long as the physical properties are not impaired.

In the present invention, a chain transfer agent can be used in the polymerization reaction for molecular weight adjustment for the purpose of improving adhesion.
As the chain transfer agent, stearyl mercaptan, t-dodecyl mercaptan, mercaptopropionic acid derivative, thioglycolic acid derivative and the like can be used.
These chain transfer agents are preferably about 0.01 to 1 part by weight, more preferably 0.05 to 0.5 parts by weight, based on 100 parts by weight of the total radical polymerizable unsaturated monomer (A). preferable.

  As an emulsifier used when polymerizing the radically polymerizable unsaturated monomer (A) in an aqueous medium, a reactive emulsifier having at least one radical polymerizable group in the structure, and / or a non-reactive emulsifier, A conventionally well-known thing can be used arbitrarily.

  Reactive emulsifiers having one or more radically polymerizable groups in the structure can be further roughly classified into anionic and nonionic nonionic ones. The anionic reactive emulsifier having one or more radically polymerizable unsaturated groups may be used singly or in combination.

  Specific examples of the anionic reactive emulsifier are shown below, but the emulsifiers that can be used in the present invention are not limited to those described below.

  Alkyl ether type (as commercial products, for example, Aqualon KH-05, KH-10, KH-20 manufactured by Daiichi Kogyo Seiyaku Co., Ltd., Adeka Soap SR-10N, SR-20N manufactured by Asahi Denka Kogyo Co., Ltd., Kao Corporation Latemul PD-104, etc.) or sulfosuccinic acid ester-based (commercially available products include Latemul S-120, S-120A, S-180P, S-180A manufactured by Kao Corporation, Elemiol JS-2 manufactured by Sanyo Chemical Co., Ltd., etc.) )

  Furthermore, alkylphenyl ether type or alkylphenyl ester type (commercially available products include, for example, Aqualon H-2855A, H-3855B, H-3855C, H-3856, HS-05, HS-10, manufactured by Daiichi Kogyo Seiyaku Co., Ltd. HS-20, HS-30, Adeka Soap SDX-222, SDX-223, SDX-232, SDX-233, SDX-259, SE-10N, SE-20N, etc. manufactured by Asahi Denka Kogyo Co., Ltd.).

  Furthermore, (meth) acrylate sulfuric acid ester type (commercially available products include, for example, Nippon Emulsifier Co., Ltd. Antox MS-60, MS-2N, Sanyo Chemical Industries Co., Ltd., Eleminol RS-30, etc.) and phosphate ester type ( Examples of commercially available products include H-3330PL manufactured by Daiichi Kogyo Seiyaku Co., Ltd. and Adeka Soap PP-70 manufactured by Asahi Denka Kogyo Co., Ltd.).

In the present invention, if necessary, a nonionic reactive emulsifier can be used together with the above-mentioned anionic reactive emulsifier or alone.
Examples of nonionic reactive emulsifiers that can be used in the present invention include alkyl ethers, alkylphenyl ethers or alkylphenyl esters, and (meth) acrylate sulfates.
As a commercially available product of alkyl ether, Adeka Soap ER-10, ER-20, ER-30, ER-40 manufactured by Asahi Denka Kogyo Co., Ltd., Latemul PD-420, PD-430, PD-450 manufactured by Kao Corporation Etc.).
Examples of commercially available alkyl phenyl ether or alkyl phenyl ester products include, for example, Aqualon RN-10, RN-20, RN-30, RN-50, manufactured by Daiichi Kogyo Seiyaku Co., Ltd., Adeka Soap NE manufactured by Asahi Denka Kogyo Co., Ltd. -10, NE-20, NE-30, NE-40, etc.).
Examples of commercially available (meth) acrylate sulfate esters include RMA-564, RMA-568, and RMA-1114 manufactured by Nippon Emulsifier Co., Ltd.).

  When obtaining the aqueous dispersion of the present invention, as long as it does not adversely affect the performance of the resin composition obtained, it is non-reactive as necessary with a reactive emulsifier having one or more radically polymerizable groups. An emulsifier can be used in combination.

Non-reactive emulsifiers can be broadly classified into nonionic and anionic types.
Examples of non-reactive nonionic emulsifiers include polyoxyethylene alkyl ethers such as polyoxyethylene lauryl ether and polyoxyethylene stearyl ether, polyoxyethylene alkyl such as polyoxyethylene octyl phenyl ether and polyoxyethylene nonyl phenyl ether Sorbitan higher fatty acid esters such as phenyl ethers, sorbitan monolaurate, sorbitan monostearate, sorbitan trioleate, polyoxyethylene sorbitan higher fatty acid esters such as polyoxyethylene sorbitan monolaurate, polyoxyethylene monolaurate, Polyoxyethylene higher fatty acid esters such as polyoxyethylene monostearate, oleic acid monoglyceride, stearic acid monoglyceride, etc. Glycerine higher fatty acid esters can be exemplified polyoxyethylene-polyoxypropylene block copolymers and the like. Or polyoxyethylene distyrenated phenyl ether etc. are mentioned.

  Examples of non-reactive anionic emulsifiers include higher fatty acid salts such as sodium oleate, alkyl aryl sulfonates such as sodium dodecylbenzene sulfonate, alkyl sulfate esters such as sodium lauryl sulfate, and polyoxyethylene lauryl ether sulfate. Polyoxyethylene alkyl ether sulfates such as sodium, polyoxyethylene alkylaryl ether sulfates such as sodium polyoxyethylene nonylphenyl ether sulfate, sodium monooctyl sulfosuccinate, sodium dioctyl sulfosuccinate, sodium polyoxyethylene lauryl sulfosuccinate And alkylsulfosuccinic acid ester salts and derivatives thereof. Alternatively, polyoxyethylene distyrenated phenyl ether sulfate ester salts may be mentioned.

  The usage-amount of the emulsifier used in this invention is not necessarily limited, According to the physical property calculated | required when the aqueous dispersion obtained is finally used, it can select suitably. For example, the emulsifier is preferably 0.1 to 30 parts by weight, more preferably 0.3 to 20 parts by weight, based on 100 parts by weight of the total amount of the monomers (A) to be subjected to polymerization. More preferably, it is in the range of 5 to 10 parts by weight.

  When obtaining an aqueous dispersion in the present invention, in order to increase the affinity for an aqueous medium within a range that does not adversely affect the performance of a coating film or an adhesive mainly composed of the aqueous dispersion, A colloid can also be used in combination.

Examples of the water-soluble protective colloid include polyvinyl alcohols such as partially saponified polyvinyl alcohol, fully saponified polyvinyl alcohol, and modified polyvinyl alcohol; for example, cellulose derivatives such as hydroxyethyl cellulose, hydroxypropyl cellulose, carboxymethyl cellulose salt, and guar gum Natural polysaccharides such as these can be used, and these can be used singly or in combination.
The amount of the water-soluble protective colloid used is about 0.1 to 5 parts by weight, more preferably 0.5 to 2 parts by weight per 100 parts by weight of the total radical polymerizable unsaturated monomer (A).

Moreover, in this invention, various crosslinking agents can be added in order to improve the intensity | strength and adhesiveness of the film | membrane formed from the resin composition obtained.
Examples of the crosslinking agent include an epoxy compound, an isocyanate compound, an oxazoline compound, a hydrazide compound, a titanium compound, a zirconium compound, a carbodiimide compound, an aziridine compound, an aluminum compound, and the silane compound, and at least one of these can be used.

  Examples of the epoxy compound used in the present invention include glycerol diglycidyl ether, (poly) glycerol diglycidyl ether, (poly) ethylene glycol diglycidyl ether, (poly) propylene glycol diglycidyl ether, glycidol, epichlorohydrin, Examples include epibromohydrin and α-methylepichlorohydrin. In the present specification, “(poly)” represents a polymer including oligomers such as dimers and trimers.

  Examples of the isocyanate compound used in the present invention include aromatic, aliphatic and cycloaliphatic organic polyisocyanates such as 2,4-tolylene diisocyanate, diphenylmethane diisocyanate, and hexamethylene diisocyanate, or mixtures thereof and these organic polyisocyanates. Examples include blocked isocyanate obtained by blocking an isocyanate compound with a blocking agent.

  Examples of the oxazoline compound used in the present invention include 1,2-ethylenebisoxazoline, 2-cyclohexyl-2-oxazoline, 2- (2′-cyclohexenyl) -2-oxazoline, 2-oxazoline, 2-methyl- 2-oxazoline, 2-ethyl-2-oxazoline, 2-isopropyl-2-oxazoline, 2-n-propyl-2-oxazoline, etc., or a mixture thereof and a polymer thereof can be mentioned.

  Examples of the hydrazide compound used in the present invention include 1,3-bis (hydrazinocarboethyl) -5-isopropylhydantoin and 7,11-octadecadien-1,18-dicarbohydrazide dipic acid dihydrazide. It is done.

  Examples of the titanium compound used in the present invention include dihydroxytitanium bislactate, diisopropoxytitanium bis (triethanolamate), tetramethoxytitanate, polyhydroxytitanium stearate, titanium acetylacetonate, titanium tetraacetylacetonate, and tetraisopropyl. Examples include titanate.

  Examples of the zirconium compound used in the present invention include zirconium acetate, zirconium tributoxy monostearate, zirconium tetraacetyl acetonate, zirconium monoacetyl acetonate, tetra n-propoxydil zirconium, tetra n-butoxydil zirconium, zirconium carbonate. Examples include ammonium, zirconium oxychloride, and zirconium sulfate.

  Examples of the carbodiimide compound used in the present invention include p-phenylene (poly) carbodiimide, dicyclohexyl (poly) carbodiimide, diisopropyl (poly) carbodiimide, dimethyl (poly) carbodiimide and diisobutyl (poly) carbodiimide.

  Examples of the aziridine compound used in the present invention include diphenylmethane-bis-4,4′-N, N′-diethyleneurea and 2,2-bishydroxymethyl-butanol-tris [3- (1-aziridinyl) propionate. ] Etc. are mentioned.

  Examples of the aluminum compound used in the present invention include aluminum chloride and aluminum nitrate.

  In the present invention, the epoxy compound, isocyanate compound, oxazoline compound, hydrazide compound, titanium compound, zirconium compound, silane compound, carbodiimide compound, aziridine compound and aluminum compound may be used alone or in combination of two or more. May be used.

  In the resin composition of the present invention, the content of the crosslinking agent is preferably 0.01 to 40 parts by weight, more preferably 100 parts by weight of the polyamide resin, from the viewpoint of film hardness and adhesiveness. Is preferably 0.1 to 30 parts by weight.

  In the resin composition of the present invention, an adhesion aid may be used in combination in order to increase the adhesiveness within a range that does not adversely affect the performance of the coating film or adhesive obtained from the resin composition.

Examples of the above-mentioned adhesion assistant include tackifier, vinyl chloride vinyl acetate resin, SBR, NBR and the like, and these can be used singly or in a combination of plural kinds.
The amount of the adhesion assistant is about 1 to 30 parts by weight, more preferably 5 to 20 parts by weight, per 100 parts by weight of the total radical polymerizable unsaturated monomer (A).

Furthermore, various organic particles and inorganic particles may be added mainly for the purpose of improving adhesiveness.
Organic particles include epoxy resin, melamine resin, urea resin, acrylic resin, polyimide resin, Teflon (registered trademark) resin, polyethylene resin, polyester resin, polyurethane resin, polyamide resin, etc. Can be mentioned.
Examples of the inorganic particles include silica, talc, magnesium carbonate, calcium carbonate, natural mica, synthetic mica, aluminum hydroxide, precipitated barium sulfate, precipitated barium carbonate, barium titanate, and barium sulfate.
You may use the said particle | grain 1 type or in mixture of 2 or more types. The particles preferably have an average particle size of 10 μm or less, and more preferably 5 μm or less.

  Hereinafter, the effects of the present invention will be described in more detail by way of examples, but the present invention is not limited thereto. In addition, in an example, a part shows a weight part and% shows weight%.

[Example 1]
In a reaction vessel equipped with a stirrer, a thermometer, a dropping funnel and a refluxer, 1.9 parts by weight of Aqualon KH-10 (Daiichi Kogyo Seiyaku Co., Ltd.) as ion-exchanged water 87.5 and an anionic reactive emulsifier, polyester An aqueous dispersion of pH 9.5 was charged with 622.6 parts by weight of Sepoljon ES-900 (non-volatile content: 40%) manufactured by Sumitomo Seika Co., Ltd. and 2.5 parts by weight of 25% aqueous ammonia as an aqueous dispersion of resin. Got.

  Next, 7.8 parts by weight of acrylonitrile, 33.1 parts by weight of tert-butyl methacrylate, 0.5 parts by weight of glycidyl methacrylate, 5.7 parts by weight of styrene, methyl methacrylate as the radical polymerizable unsaturated monomer (A) 26.9 parts by weight, 0.5 part by weight of acrylic acid, 30.5 parts by weight of 2-ethylhexyl acrylate, 0.5 part by weight of divinylbenzene and 1.0 part by weight of 2-hydroxyethyl methacrylate, 58. 3 parts by weight and 3.3 parts by weight of Aqualon KH-10 as an anionic reactive emulsifier were mixed in advance to obtain a pre-emulsion.

  After raising the internal temperature of the reaction vessel to 60 ° C. and sufficiently purging with nitrogen, 5% of 2,2′-azobis (2-amidinopropane) dihydrochloride (V-50) as the cationic radical initiator (b1) 3.7 parts by weight of aqueous solution and 5% aqueous solution of 2,2′-azobis [N- (2-carboxyethyl) -2-methylpropionamidine] hydrate (VA-057) as zwitterionic radical initiator (b2) 1.9 parts by weight were added.

After completion of the initiator addition, the inside of the reaction system was maintained at 60 ° C. for 5 minutes, and then the pre-emulsion was dropped into the reaction vessel over 3 hours while maintaining the internal temperature at 60 ° C. One hour after the completion of dropping, 0.3 part by weight of a 5% aqueous solution of V-50 was added four times every 30 minutes, and stirring was continued for another hour. During the emulsion polymerization, the pH of the polymerization reaction solution was maintained at 9.0. After completion of the reaction, the temperature was cooled to 30 ° C. to obtain an aqueous emulsion of a composite resin having a nonvolatile content concentration of 40.3%.
The glass transition temperature (calculated value) of the acrylic copolymer part in the aqueous emulsion of the obtained composite resin is 41 ° C., and the minimum film-forming temperature (hereinafter abbreviated as MFT) of the aqueous emulsion of the composite resin is 40. ° C.

  Next, the obtained aqueous emulsion was coated on the surface of a 3 mm thick glass plate with a 10 mil applicator and dried at 100 ° C. for 5 minutes to obtain a coating film.

[Example 2]
Nonvolatile content in the same manner as in Example 1 except that Dispacol U-53 (nonvolatile content: 40%) manufactured by Sumika Bayer Urethane Co., Ltd. was used as an aqueous dispersion of polyurethane resin instead of Sephojon ES-900. An aqueous emulsion of a composite resin having a concentration of 40.4% was obtained.
The glass transition temperature (calculated value) of the acrylic copolymer part in the aqueous emulsion of the obtained composite resin was 41 ° C., and the MFT of the aqueous emulsion was 40 ° C.
Next, the same operation as in Example 1 was performed using the obtained aqueous emulsion to obtain a coating film.

[Example 3]
Instead of Sepouljon ES-900, 553.4 parts by weight of Aquatex HA-1100 (non-volatile content: 45%) manufactured by Chuo Science Industrial Co., Ltd. was used as an aqueous dispersion of polyolefin resin, and ion-exchanged water in the reaction vessel was used. An aqueous emulsion of a composite resin having a nonvolatile content concentration of 40.0% was obtained in the same manner as in Example 1 except that the amount was changed to 156.7 parts by weight.
The glass transition temperature (calculated value) of the acrylic copolymer part in the obtained composite resin aqueous emulsion was 41 ° C., and the MFT of the composite resin aqueous emulsion was 60 ° C.
Next, the same operation as in Example 1 was performed using the obtained aqueous emulsion to obtain a coating film.

[Example 4]
Except that 622.6 parts by weight of Chemipearl W-300 (nonvolatile content: 40%) manufactured by Mitsui Chemicals, Inc. was used as an aqueous dispersion of polyolefin resin instead of Sephojon ES-900, the same procedure as in Example 1 was performed. An aqueous emulsion of a composite resin having a nonvolatile content concentration of 40.1% was obtained.
The glass transition temperature (calculated value) of the acrylic copolymer part in the aqueous emulsion of the obtained composite resin was 41 ° C., and the MFT of the aqueous emulsion was 70 ° C.
Next, the same operation as in Example 1 was performed using the obtained aqueous emulsion to obtain a coating film.

[Comparative Example 1]
As the cationic radical initiator (b1), 5.6 parts by weight of a 5% aqueous solution of 2,2′-azobis (2-amidinopropane) dihydrochloride (V-50) was used, and no zwitterionic radical initiator was used. Except for this, the same operation as in Example 1 was performed, but the entire reaction system was thickened, and a stable aqueous emulsion could not be obtained.

[Comparative Example 2]
As a zwitterionic radical initiator (b2), 5.6 parts by weight of a 5% aqueous solution of 2,2′-azobis [N- (2-carboxyethyl) -2-methylpropionamidine] hydrate (VA-057) was used. The same operation as in Example 1 was performed except that the cationic radical initiator was not used, but the entire reaction system was thickened and a stable aqueous emulsion could not be obtained.

[Comparative Example 3]
The same operation as in Example 1 was performed except that 5.6 parts by weight of a 5% aqueous solution of potassium persulfate was used as a radical initiator, but the entire reaction system gelled and a stable aqueous emulsion could not be obtained. It was.

The aqueous emulsion and coating film obtained in each example and comparative example were evaluated by the following methods. The results are shown in Tables 1 and 2.
<1>: The amount of resin adhering to the reaction vessel after completion of the polymerization stability reaction and the amount of aggregate after filtration with a filter cloth were visually evaluated. The evaluation criteria are as follows.
A: Good.
○: A level with no practical problem.
Δ: Slightly problematic level.
X: It is bad.

<2>: Uniformity of film The uniformity of the film when the coating film obtained in each example was observed visually was evaluated.
5: There is no unevenness.
4: Very slight unevenness can be confirmed.
3: Unevenness can be confirmed partially.
2: There is unevenness throughout.
1: The area | region of an acrylic copolymer and other resin is completely separated.

<3>: Stability over time The change in viscosity was evaluated when the aqueous emulsion obtained in each Example was placed in a sealed glass container and left in a thermostatic bath at 50 ° C. for 30 days. Furthermore, the aggregate on the bottom of the glass container was visually evaluated. The evaluation criteria are as follows.
5: The absolute value of the viscosity change rate is less than 10%, and no aggregates are observed.
4: The absolute value of the viscosity change rate is less than 10%, and agglomerates are slightly observed.
3: Absolute value of viscosity change rate is 10% or more and less than 30%, or many aggregates are observed.
2: Absolute value of viscosity change rate is 30% or more, or very many aggregates are observed.
1: Aqueous emulsion gels.
The viscosity change rate was calculated by the following formula [I].
Viscosity change rate (%) = (viscosity after storage−viscosity before storage) / viscosity before storage × 100 [I]

The aqueous dispersion of the resin composition obtained by the production method of the present invention includes water-based ink, fiber treatment agent, fiber sealant, glass fiber sizing agent, paper treatment agent, various paints, lubricants, steel sheet surface treatment agent, surface It can be preferably used for a wide range of applications such as a hot melt adhesive such as a modifier and interlining adhesive.

Claims (6)

Radical polymerizable unsaturated monomer using cationic radical polymerization initiator (b1) and zwitterionic radical polymerization initiator (b2) in the presence of a basic aqueous dispersion of resin (C) other than polyamide resin A method for producing an aqueous dispersion of a resin composition, wherein (A) is polymerized in an aqueous medium. The method for producing an aqueous dispersion of a resin composition according to claim 1, wherein the resin (C) other than the polyamide resin is at least one selected from the group consisting of a polyester resin, a polyurethane resin, and a polyolefin resin. The ratio of the radically polymerizable unsaturated monomer (A) and the resin (C) other than the polyamide resin is (A) / (C) = 95-5 / 5-95 (weight ratio). Item 3. A method for producing an aqueous dispersion of the resin composition according to Item 1 or 2. The total amount of the cationic radical polymerization initiator (b1) and the zwitterionic radical polymerization initiator (b2) is 0.01 to 1 part by weight with respect to 100 parts by weight of the radically polymerizable unsaturated monomer (A). A method for producing an aqueous dispersion of a resin composition according to any one of claims 1 to 3. The ratio of the cationic radical polymerization initiator (b1) to the zwitterionic radical polymerization initiator (b2) is (b1) / (b2) = 95-5 / 5-95 (weight ratio). A method for producing an aqueous dispersion of a resin composition according to any one of claims 1 to 4. Radical polymerizable unsaturated monomer using cationic radical polymerization initiator (b1) and zwitterionic radical polymerization initiator (b2) in the presence of a basic aqueous dispersion of resin (C) other than polyamide resin An aqueous dispersion of a resin composition obtained by polymerizing (A) in an aqueous medium.