JP2009235140A - Composite resin fine particle and method for producing it - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a composite resin particle having a surface with controlled hydrophilicity-hydrophobicity and good solvent dispersibility and consisting of an amino resin and an acrylic resin, and a method for easily producing the composite resin fine particle. <P>SOLUTION: In the composite resin fine particle, a particle of the amino resin (A) is coated with the acrylic resin (B), and the amino resin (A) is prepared by the addition condensation reaction of a triazine ring-containing compound (a1), which is reactive with an aldehyde compound by addition condensation reaction, and an aldehyde compound (a2), while the acrylic resin (B) is prepared by radial polymerization of ethylenically unsaturated monomers including an ethylenically unsaturated monomer (b1) having a functional group, which is reactive with an aldehyde compound by addition reaction, or a functional group, which is reactive with a methylol group by condensation or addition reaction, an ethylenically unsaturated monomer (b2) having a dialkylamino group, and an ethylenically unsaturated monomer (b3) with ≤5 wt.% solubility in water. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to composite resin fine particles having good solvent dispersibility. More specifically, the present invention relates to composite resin fine particles whose surface of amino resin fine particles is coated with an acrylic resin and capable of controlling hydrophilicity and hydrophobicity. The composite resin fine particles obtained in the present invention have good dispersibility in an organic solvent, and when added to a binder resin or monomer, the composite resin fine particles are uniformly dispersed in the coating film, and paints, inks, antiblocking agents, and light diffusing agents. , Useful as light scattering agent, spacer, matting agent, lubricant.

  Amino resin fine particles containing a melamine resin have been used as an antiblocking agent, a light diffusing agent, a light scattering agent, a spacer, a matting agent, a lubricant, and the like because of their excellent physical properties. Conventionally, amino resin fine particles are known to be produced by various methods. For example, a method in which an initial condensate of benzoguanamine or a mixture of benzoguanamine and melamine and formaldehyde is emulsified with a hydrophilic protective colloid, followed by addition of a curing catalyst such as an acid for condensation curing (Patent Document 1), melamine and , A method in which an initial condensation product of formaldehyde and methanol is condensed and cured by adding a curing catalyst such as an acid in a water-soluble polymer containing a carboxyl group (Patent Document 2), and an initial condensation product of melamine and formaldehyde is colloidal. A method of condensing and curing by adding a curing catalyst such as an acid in the presence of silica has been proposed (Patent Document 3).

  Amino resin fine particles obtained by these methods are known to have positive chargeability and high hydrophilicity. In general, the fine particles are often used by mixing with a binder resin. However, when these amino resin fine particles are used by being added to an organic solvent or a low-polar binder resin, the particles are likely to aggregate due to their high hydrophilicity, and it is difficult to disperse them to the primary particles. In many cases, the effect could not be demonstrated.

In response to this problem, a method is disclosed in which amino resin fine particles are treated with an alkyl group-containing acid (Patent Document 4), or amino resin fine particles are treated with an alkylamine to hydrophobize the surface (see Patent Document 5). . In this method, amino groups and methylol groups remaining on the particle surface are reacted with alkyl group-containing acids or alkylamines, but the low molecular weight solution present in the particle dispersion medium before the surface hydrophobization treatment. In addition, a cleaning process for removing the surfactant or water-soluble polymer adsorbed on the particle surface is necessary, and the manufacturing process becomes complicated. In general, it is difficult to control the residual amount of amino groups or methylol groups on the particle surface, and the degree of hydrophobicity on the surface of the fine particles cannot be adjusted. As described above, the conventional technique has a problem in the reproducibility and productivity of the target fine particles.
JP 2002-293854 A Japanese Patent No. 2539690 JP 2003-306521 A Japanese Patent Laid-Open No. 2003-138023 JP 2005-97575 A

  The object of the present invention is to eliminate the above-mentioned problems of the conventional amino resin fine particle technology, control the hydrophilic / hydrophobic properties of the particle surface, and have good solvent dispersibility, and composite resin fine particles comprising an amino resin and an acrylic resin The purpose is to obtain. Furthermore, it aims at providing the method of manufacturing the said composite resin microparticles | fine-particles easily.

The first invention of the present invention is a composite resin fine particle obtained by coating particles of an amino resin (A) with an acrylic resin (B),
The amino resin (A) is a resin obtained by addition-condensation reaction of a triazine ring-containing compound (a1) and an aldehyde compound (a2) capable of addition-condensation reaction with an aldehyde compound, and
The acrylic resin (B) comprises an ethylenically unsaturated monomer (b1) having a functional group capable of addition reaction with an aldehyde compound or a functional group capable of condensation or addition reaction with a methylol group, and an ethylenically unsaturated monomer having a dialkylamino group. A resin obtained by radical polymerization of an ethylenically unsaturated monomer containing a saturated monomer (b2) and an ethylenically unsaturated monomer (b3) having a solubility in water of 5% by weight or less. The present invention relates to composite resin fine particles.

  The second invention relates to the composite resin fine particles of the first invention obtained by subjecting an acrylic resin (B), a triazine ring-containing compound (a1), and an aldehyde compound (a2) to an addition condensation reaction in an aqueous solvent.

  In the third invention, the ethylenically unsaturated monomer (b1) is at least one selected from acrylamide, 2-vinyl-4,6-diamino-s-triazine, and N-methylolacrylamide. Or it relates to the composite resin fine particles of the second invention.

  The fourth invention is the composite according to any one of the first to third inventions, wherein the ethylenically unsaturated monomer (b2) is at least one selected from N, N-dimethylacrylamide and N, N-diethylacrylamide. It relates to resin fine particles.

  In the fifth invention, the acrylic resin (B) comprises 1 to 30% by weight of ethylenically unsaturated monomer (b1), 10 to 70% by weight of ethylenically unsaturated monomer (b2), And 0.1 to 75% by weight of the ethylenically unsaturated monomer (b3), and the composite resin fine particles according to any one of the first to fourth inventions obtained by radical polymerization of an ethylenically unsaturated monomer.

  The sixth invention relates to the composite resin fine particles according to any one of the first to fifth inventions, wherein the acrylic resin (B) is colloidal in an aqueous solvent.

  The seventh invention relates to the composite resin fine particles of any one of the first to sixth inventions having an average particle diameter of 0.01 to 20 μm and a coefficient of variation of the particle diameter of less than 20%.

Further, the eighth invention relates to an ethylenically unsaturated monomer (b1) having a functional group capable of addition reaction with an aldehyde compound or a functional group capable of condensation or addition reaction with a methylol group in an aqueous solvent, and a dialkylamino. An ethylenically unsaturated monomer comprising a group-containing ethylenically unsaturated monomer (b2) and an ethylenically unsaturated monomer (b3) having a solubility in water of 5% by weight or less. A first step of polymerization to obtain an acrylic resin (B);
A composite resin fine particle comprising: the acrylic resin (B), a triazine ring-containing compound (a1) capable of addition condensation with an aldehyde compound, and a second step of addition condensation reaction of the aldehyde compound (a2). It relates to a manufacturing method.

  According to the present invention, composite resin fine particles composed of an amino resin and an acrylic resin having good solvent dispersibility can be provided. Moreover, the manufacturing method which can control the hydrophilic property and hydrophobicity of the composite resin fine particle which consists of an amino resin and an acrylic resin was able to be provided. The composite resin fine particles obtained by the present invention have good dispersibility even in organic solvents and low-polar binder resins, and can be used as paints, inks, antiblocking agents, light diffusing agents, light scattering agents, spacers, matting agents, and lubricants. Demonstrate sufficient effect.

  The composite resin fine particles of the present invention are fine particles obtained by bonding an acrylic resin (B) having a specific functional group to the surface of amino resin (A) fine particles. By adjusting the composition of the acrylic resin (B), it is possible to control the hydrophilicity / hydrophobicity of the particle surface, introduce functional groups, and further control the average particle size and particle size distribution.

  The composite resin fine particles obtained in the present invention preferably have an average particle size in the range of 0.01 to 20 μm. By adjusting the composition of the acrylic resin (B), it is possible to obtain monodispersed fine particles having no classification step and having a coefficient of variation in particle diameter of less than 20%.

  The average particle diameter referred to in the present invention is the number average of 100 particles measured with an optical microscope, and the variation coefficient of the particle diameter is a numerical value obtained by statistically calculating the 100 particle diameters, and obtained by the following equation. is there.

    Coefficient of variation (%) = (standard deviation / average particle diameter) × 100

  When used for optical applications such as a light diffusing agent, a light scattering agent, and a spacer, it is preferable that the average particle diameter is 0.01 to 20 μm and the coefficient of variation of the particle diameter is less than 20%. Moreover, it is especially preferable that it is an average particle diameter of 0.1-10 micrometers, and the variation coefficient of a particle diameter is less than 10%. In the optical application, the size and uniformity of the fine particles greatly affect the optical characteristics, but the fine particles of the present invention can sufficiently satisfy the optical characteristics in these applications.

  First, the amino resin (A) will be described. The amino resin (A) may be expressed as a triazine ring-containing compound (a1) [hereinafter referred to as “triazine ring-containing compound (a1)” which can undergo an addition condensation reaction with an aldehyde compound. And an aldehyde compound (a2).

  Examples of the triazine ring-containing compound (a1) that can undergo an addition condensation reaction with an aldehyde compound include amino compounds having a triazine ring, and specific examples thereof include guanamines such as melamine, benzoguanamine, and acetoguanamine. It is not limited to these, It can also use 2 or more types together. Usually, melamine which is the cheapest and has many functional groups is used as a main component, and various physical properties are adjusted by co-condensing a triazine ring-containing compound other than melamine.

  Further, examples of compounds that can be co-condensed with the triazine ring-containing compound (a1) include ureas such as urea, thiourea, and ethylene urea, phenols such as phenol, cresol, alkylphenol, resorcin, hydroquinone, pyrogallol, and aniline. It can also be used in combination.

  Examples of the aldehyde compound (a2) include aliphatic, alicyclic, aromatic, and heterocyclic aldehydes, condensates thereof, and compounds capable of generating the aldehyde. Examples include formaldehyde, acetaldehyde, propionaldehyde, butyraldehyde, isobutyraldehyde, paraformaldehyde, paraacetaldehyde, and the like. Formaldehyde and paraformaldehyde are preferable, and an aqueous solution dissolved in water is preferably used as a solvent. A commercially available 37% concentration formalin aqueous solution, which is an aqueous solution of formaldehyde, is the cheapest and can be easily used.

  If the reaction of the triazine ring-containing compound (a1) and the aldehyde compound (a2) is, for example, melamine and formaldehyde, it can be reacted up to 6 mol of formaldehyde with respect to 1 mol of melamine. Usually, a linear polymer is produced when they are reacted in equimolar amounts. In order to obtain fine particles having a cross-linked structure, tens of more aldehyde compounds (a2) are required. Theoretically, the amino resin (A) of the present invention is synthesized from an aldehyde compound (a2) that is more than 1.0-fold mol relative to the triazine ring-containing compound (a1).

  The amino resin (A) of the present invention is formed by insolubilizing the product obtained in the addition reaction step under basicity by three-dimensional crosslinking in the condensation reaction step in the presence of an acid catalyst. Therefore, it is easier to obtain crosslinked fine particles when the aldehyde compound (a2) is excessive to some extent. If the amount of the aldehyde compound (a2) is small, the number of cross-linking points at the initial stage of the reaction is reduced, so that the two-dimensional cross-linking is insolubilized or the particles are fused in the process of forming the fine particles. Primary particles cannot be obtained. However, if the aldehyde compound (a2) is excessively present, it may remain in the system as an unreacted substance, which may cause environmental pollution. For this reason, the aldehyde compound (a2) is preferably 2.0 to 4.0 moles, more preferably 2.5 to 3.5 moles, relative to the triazine ring-containing compound (a1).

  Next, the acrylic resin (B) of the present invention will be described. The acrylic resin (B) can be obtained by polymerizing an ethylenically unsaturated monomer in an aqueous solvent using a radical initiator. The ethylenically unsaturated monomer includes an ethylenically unsaturated monomer (b1) [hereinafter referred to as "ethylenically unsaturated monomer" having a functional group that undergoes an addition reaction with an aldehyde compound or a functional group that undergoes a condensation or addition reaction with a methylol group. May be referred to as “mer (b1)”. ], An ethylenically unsaturated monomer having a dialkylamino group (b2) [hereinafter sometimes referred to as “ethylenically unsaturated monomer (b2)”. And an ethylenically unsaturated monomer (b3) having a solubility in water of 5% by weight or less [hereinafter sometimes referred to as “ethylenically unsaturated monomer (b3)”. ] Is included. In the ethylenically unsaturated monomers (b1) and (b2) specified in the present invention, even if their solubility in water is 5% by weight or less, in the present invention, It is not included in the “saturated monomer (b3)”.

  Each ethylenically unsaturated monomer has the following role. The ethylenically unsaturated monomer (b1) chemically bonds the amino resin (A) and the acrylic resin (B). That is, a functional group capable of addition reaction with an aldehyde compound derived from the ethylenically unsaturated monomer (b1) present in the acrylic resin (B) or a functional group capable of condensation or addition reaction with a methylol group is converted into an amino resin (A In the step of synthesizing the acrylic resin (B) and the amino resin (A) by addition condensation reaction with the triazine ring compound (a1) and the aldehyde compound (a2) constituting the amino resin (A). Can do. The ethylenically unsaturated monomer (b2) has a function of stabilizing the fine particles in an aqueous solvent at the time of synthesizing the composite resin fine particles. The ethylenically unsaturated monomer (b3) contains fine particles in an organic solvent. When dispersed, it has a function of stably dispersing fine particles without agglomeration.

Among the ethylenically unsaturated monomers (b1) having a functional group capable of addition reaction with an aldehyde compound or a functional group capable of condensation or addition reaction with a methylol group, an ethylenic group having a functional group capable of addition reaction with an aldehyde compound Unsaturated monomer (b1-1) [hereinafter referred to as “ethylenically unsaturated monomer (b1-1)”. ] Is a compound having a functional group capable of reacting with the aldehyde compound (a2) to form a methylol group and a radically polymerizable ethylenically unsaturated group. Specific examples of the functional group capable of reacting with the aldehyde compound (a2) to form a methylol group include an amino group, an amide group, an aldehyde group, a phenol group, and a functional group having an active hydrogen such as an aromatic hydrocarbon. Can be mentioned. Specific examples of the radical polymerizable ethylenically unsaturated group include a vinyl group and a (meth) acryloyl group. Examples of the ethylenically unsaturated monomer (b1-1) include amino group-containing ethylenically unsaturated monomers such as 2-vinyl-4,6-diamino-s-triazine, tetramethylpiperidyl (meth) acrylate, and allylamine. Mer;
Amide group-containing ethylenic unsaturation such as (meth) acrylamide, t-butyl (meth) acrylamide, N, N-dimethylaminopropyl (meth) acrylamide, N-isopropyl (meth) acrylamide, diacetone acrylamide and N-vinylacetamide Monomer;
Aldehyde-containing ethylenically unsaturated monomers such as (meth) acrylaldehyde and crotonaldehyde;
Examples include amide groups such as N-vinylformamide and aldehyde group-containing ethylenically unsaturated monomers.

Moreover, in the ethylenically unsaturated monomer (b1) having a functional group capable of addition reaction with an aldehyde compound or a functional group capable of condensation or addition reaction with a methylol group, a functional group capable of condensation or addition reaction with a methylol group The ethylenically unsaturated monomer (b1-2) having the formula [hereinafter sometimes referred to as “ethylenically unsaturated monomer (b1-2)”. ] Is a step in which the adduct of the triazine ring-containing compound (a1) and the aldehyde compound (a2) condenses, a functional group capable of condensation or addition reaction with the methylol group in these adducts, and radical polymerizable ethylene. It is a compound which has an ionic unsaturated group. Specific examples of functional groups that can undergo condensation or addition reactions with methylol groups include methylol groups, hydroxyl groups, epoxy groups, carboxyl groups, acid anhydride groups, chloroformyl groups, mercapto groups, cyano groups, amide groups, amino groups, and the like. Can be mentioned. Specific examples of the radical polymerizable ethylenically unsaturated group include a vinyl group and a (meth) acryloyl group. As the ethylenically unsaturated monomer (b1-2), a methylol group-containing ethylenically unsaturated monomer such as N-methylol (meth) acrylamide;
2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, 2-hydroxy-3-phenoxypropyl (meth) acrylate, 2 -(Meth) acryloyloxyethyl-2-hydroxyethylphthalic acid, 1,4-cyclohexanedimethanol mono (meth) acrylate, dipropylene glycol (meth) acrylate, glycerin mono (meth) acrylate, polyethylene glycol mono (meth) Hydroxyl group-containing ethylenically unsaturated monomers such as acrylate and polypropylene glycol mono (meth) acrylate;
Epoxy group-containing unsaturated monomers such as glycidyl (meth) acrylate, allyl glycidyl ether, 1,2-epoxy-4-vinylcyclohexane, 3,4-epoxycyclohexylmethyl methacrylate;
(Meth) acrylic acid, 2- (meth) acryloyloxyethyl succinic acid, 2- (meth) acryloyloxyethyl hexahydrophthalic acid, 2- (meth) acryloyloxyethyl phthalic acid, 4-vinylbenzoic acid, Carboxyl group or acid anhydride group-containing ethylenically unsaturated monomer such as (anhydrous) itaconic acid, (anhydrous) citraconic acid, (anhydrous) maleic acid;
Chloroformyl group-containing ethylenically unsaturated monomers such as (meth) acrylic acid chloride;
Cyano group-containing ethylenically unsaturated monomers such as (meth) acrylonitrile;
Amide group-containing ethylenically unsaturated monomers such as (meth) acrylamide, t-butyl (meth) acrylamide, N, N-dimethylaminopropyl (meth) acrylamide, N-isopropyl (meth) acrylamide, diacetone acrylamide;
Amino group-containing ethylenically unsaturated monomers such as 2-vinyl-4,6-diamino-s-triazine, tetramethylpiperidyl (meth) acrylate, allylamine;
Is mentioned.

  Among the ethylenically unsaturated monomers (b1), the same reaction as the addition reaction between the triazine ring-containing compound (a1) and the aldehyde compound (a2) or the condensation reaction of the adduct formed by the addition reaction. Preferred are ethylenically unsaturated monomers containing amide groups, amino groups, or methylol groups, which have a speed. If the reaction with the acrylic resin (B) is too slow compared to the addition condensation reaction rate between the triazine ring-containing compound (a1) and the aldehyde compound (a2), the particles may not be stabilized and may aggregate. As the ethylenically unsaturated monomer (b1), (meth) acrylamide, 2-vinyl-4,6-diamino-s-triazine, and N-methylol (meth) acrylamide are preferable.

  The ethylenically unsaturated monomer (b2) having a dialkylamino group is a water-soluble ethylenically unsaturated monomer that does not participate in the addition condensation reaction between the triazine ring-containing compound (a1) and the aldehyde compound (a2). There is a function of forming a stable layer on the fine particles when the fine particles are synthesized in an aqueous solvent. Specific examples include N, N-dimethylacrylamide, N, N-diethylacrylamide, N, N-dimethylaminoethyl (meth) acrylate, and N, N-diethylaminoethyl (meth) acrylate. Among these, N, N-dimethylacrylamide and N, N-diethylacrylamide are preferable in that they are not affected by hydrolysis in an aqueous solvent as compared with ester monomers.

The ethylenically unsaturated monomer (b3) having a solubility in water of 5% by weight or less enhances the affinity of the fine particles obtained in the present invention to an organic solvent and forms a dispersion stable layer on the fine particles in the organic solvent. Has the function of forming. The solubility in water is the solubility at 20 ° C. Specific examples of the ethylenically unsaturated monomer (b3) include alkyl (meth) acrylates having an alkyl group having 1 to 24 carbon atoms such as methyl (meth) acrylate and ethyl (meth) acrylate;
(Meth) acrylates having an aliphatic ring or aromatic ring such as cyclohexyl (meth) acrylate and benzyl (meth) acrylate;
Polyalkylene glycol mono (meth) acrylates having 1 to 24 carbon atoms, such as ethoxydiethylene glycol (meth) acrylate, methoxypolyethylene glycol mono (meth) acrylate, nonylphenoxypolyethylene glycol mono (meth) acrylate;
Examples include styrene.

  A preferable amount of the ethylenically unsaturated monomer is 1 to 30% by weight of ethylenically unsaturated monomer (b1), 10 to 70% by weight in a total of 100% by weight of the ethylenically unsaturated monomer. Ethylenically unsaturated monomer (b2), 0.1 to 75% by weight of ethylenically unsaturated monomer (b3), more preferably 5 to 20% by weight of ethylenically unsaturated monomer (B1) 25 to 60% by weight of ethylenically unsaturated monomer (b2) and 25 to 70% by weight of ethylenically unsaturated monomer (b3). When the ethylenically unsaturated monomer (b1) is less than 1% by weight, there are few binding sites between the amino resin (A) and the acrylic resin (B), and a sufficient stabilizing effect cannot be exhibited during particle synthesis. There is. On the other hand, if it exceeds 30% by weight, gelation tends to occur in the process of producing the acrylic resin (B), and even if the polymer can be polymerized without gelation, there are too many binding sites with amino resin particles, so that the stable layer spreads. The solvent dispersibility may deteriorate. When the ethylenically unsaturated monomer (b2) is less than 10% by weight, particle stability in an aqueous solvent is not sufficient, and problems such as aggregation may occur. Moreover, when it exceeds 70 weight%, it may act as a polymer flocculent. When the ethylenically unsaturated monomer (b3) is less than 0.1% by weight, the stability of the resulting fine particles in an organic solvent may not be ensured. Stability in an aqueous solvent may deteriorate.

  Further, the ethylenically unsaturated monomer (b4) other than the ethylenically unsaturated monomers (b1), (b2), and (b3) may be copolymerized with the acrylic resin (B). A further function can be imparted to the fine particles by copolymerizing the ethylenically unsaturated monomer (b4). For example, when the ethylenically unsaturated monomer (b4) having a polar group is used, the particle size control and particle size distribution control of the obtained particles can be performed depending on the amount of the polar group. Further, when the ethylenically unsaturated monomer (b4) having a cyclic ether group is used, it is possible to impart reactivity to the particle surface or to further modify the surface. Examples of the monomer (b4) include dimethylaminoethyl (meth) acrylate methyl chloride salt, dimethylaminoethyl (meth) acrylate benzyl chloride salt, 2- (meth) acryloyloxyethyl acid phosphate, and 3-ethyl-3. -Oxetanyl) methoxymethyl (meth) acrylate and the like.

  The method for producing composite resin fine particles of the present invention includes a first step of radically polymerizing the ethylenically unsaturated monomer to obtain an acrylic resin (B), the acrylic resin (B), and the triazine in an aqueous solvent. It consists of a second step of addition condensation of the ring-containing compound (a1) and the aldehyde compound (a2).

  First, the first step will be described. In the first step, the acrylic resin (B) is obtained by polymerizing the ethylenically unsaturated monomer in an aqueous solvent using a radical initiator. There is no particular limitation on the polymerization method, and a general radical polymerization method can be applied. For example, a water-soluble radical initiator is added to an aqueous solvent in which the ethylenically unsaturated monomer is uniformly dissolved, and the mixture is heated and stirred. The acrylic resin (B) is obtained in a state of being dissolved in an aqueous solvent or colloidal. Among them, the colloidal acrylic resin (B) has both hydrophilicity and hydrophobicity in a well-balanced manner, so that the characteristics of the present invention are maximized in that it can exhibit stability in both aqueous and organic solvents. You can make use of it. In the present invention, the colloidal form means that the obtained acrylic resin (B) solution is adjusted to 2% by weight with ion-exchanged water, and the turbidity measured with Nippon Denshoku Industries Haze Meter NDH-2000 is 20 0.0-70.0.

  The aqueous solvent in the first step may be any solvent that can be mixed with a solvent that dissolves the adduct of the triazine ring-containing compound (a1) and the aldehyde compound (a2) in the second step. Specifically, water or a mixed solvent of water and alcohol is preferably used. Examples of the alcohol include methanol, ethanol, isopropyl alcohol and the like.

  The radical initiator may be a general water-soluble peroxide or azo compound. Specifically, ammonium persulfate, potassium persulfate, 2,2-azobis (2-amidinopropane) dihydrochloride, 2,2-azobis {2- [N- (2-carboxyethyl) amidino] propane} tetrahydrate Etc.

  The solid content in the polymerization reaction for obtaining the acrylic resin (B) is preferably 2% by weight or more. If it is less than 2% by weight, the solid content during the subsequent synthesis of the composite resin fine particles becomes low, and the productivity may deteriorate. The reaction temperature is preferably in the range of 50 to 100 ° C, more preferably 50 to 70 ° C.

  Next, the second step will be described. In the second step, composite fine particles are obtained by addition condensation reaction of acrylic resin (B), triazine ring-containing compound (a1), and aldehyde compound (a2) in an aqueous solvent. The acrylic resin (B) is preferably used in an amount of 2.5 to 20% by weight based on 100% by weight of the total amount of the triazine ring-containing compound (a1) and the aldehyde compound (a2). If the amount is less than 2.5% by weight, the stability may be insufficient and the particles may aggregate. If the amount is more than 20% by weight, unreacted acrylic resin (B) remains, and in some cases, washing is required, which is not efficient. .

  The solid content concentration during the reaction is preferably 5 to 30% by weight from the start to the end of the reaction. If it is less than 5% by weight, the productivity is poor, and if it exceeds 30% by weight, particles may be aggregated. Solid content here means the total amount of an acrylic resin (B), a triazine ring containing compound (a1), and an aldehyde compound (a2).

  In principle, water is used as the solvent for the addition condensation reaction. Alcohol can be added if desired. When adding alcohol, it is preferable that it is 5 to 50 weight% in 100 weight% of the whole solvent. By adding 5% by weight or more of alcohol, a part of methylol group is etherified with alcohol, the condensation rate is eased, particles can be obtained more stably, and the particle size and the like can be easily controlled by adjusting various compositions. . However, if the amount of alcohol added exceeds 50% by weight, the addition reaction product may not be dissolved, or the whole solution may be gelled without forming fine particles.

  The addition condensation method of the acrylic resin (B), the triazine ring compound (a1), and the aldehyde compound (a2) is not particularly limited, and a general amino resin production method can be applied. The process is performed in the presence of a catalyst.

  First, the basic addition reaction step will be described. In this step, the triazine ring-containing compound (a1) and the aldehyde compound (a2) are subjected to an addition reaction to obtain a water-soluble methylol product. At this time, when the ethylenically unsaturated monomer (b1-1) having a functional group capable of addition reaction with an aldehyde compound is used as the ethylenically unsaturated monomer constituting the acrylic resin (B), the acrylic resin An addition reaction between the functional group derived from the ethylenically unsaturated monomer (b1-1) in (B) and the aldehyde compound (a2) also occurs, and the acrylic resin (B) is also methylolated.

  In this step, no catalyst may be used if the reaction solution is basic, and an alkali catalyst can be used if necessary. For example, sodium hydroxide, potassium hydroxide, ammonia water, triethylamine and the like can be mentioned, but are not limited thereto. Two or more types can be used in combination.

  In addition, methylol melamine, alkylmethylolated melamine, methylol benzoguanamine, alkylmethylolated benzoguanamine and the like are water-soluble condensates of a triazine monomer and formaldehyde, so that the triazine ring-containing compound (a1) and the aldehyde compound (a2) These compounds can also be used instead of or simultaneously.

  The reaction temperature is preferably in the range of 15 to 100 ° C, more preferably 20 to 90 ° C.

  Next, the condensation reaction step in the presence of an acid catalyst will be described. In this step, the adduct obtained by the basic addition reaction is further condensed to obtain the desired composite resin fine particles. In this step, fine particles are formed simultaneously with the condensation of the triazine ring-containing compound (a1) and the triazine ring-containing compound added with the aldehyde compound, and the condensation of the triazine ring-containing compounds added with the aldehyde compound. (B) also has a functional group capable of condensation or addition reaction with the methylol group obtained in the addition reaction step, which is a constituent component thereof, or the methylol group derived from the ethylenically unsaturated monomer (b1-2). A polycondensation reaction with the adduct obtained in one step results in composite resin fine particles in which the amino resin (A) particles of the present invention are coated with an acrylic resin (B).

Examples of the acid catalyst include inorganic acids such as hydrochloric acid;
Organic acids such as acetic acid, alkylbenzenesulfonic acid, naphthalenesulfonic acid, paratoluenesulfonic acid, sulfonated products of polyoxyethylene and derivatives thereof;
Aliphatic saturated dicarboxylic acids such as oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid;
Aliphatic unsaturated dicarboxylic acids such as maleic acid, fumaric acid, itaconic acid;
Aromatic dicarboxylic acids such as phthalic acid, isophthalic acid, terephthalic acid;
And dibasic acids such as sulfuric acid;
Tricarboxylic acids such as tricarballylic acid and benzenetricarboxylic acid;
Tribasic acids such as phosphoric acid, arsenic acid, boric acid;
Tetrabasic acids such as benzenetetracarboxylic acid;
Hexabasic acids such as benzenehexacarboxylic acid; but are not limited thereto.

  The amount of acid catalyst added is preferably such that the polymerization system has a pH of 6 or less, and more preferably the pH is 2-5. If the pH is higher than 6, the particle size distribution may be broadened or aggregation may occur.

  Although it becomes cloudy in 10 seconds to 5 minutes after the addition of the acid catalyst, stirring is continued at the temperature for 1 hour or longer to complete the internal crosslinking. If the crosslinking is insufficient, the fine particles may be fused or destroyed in the post-treatment. When the initial reaction temperature is a low temperature of 40 ° C. or lower, the temperature may be raised halfway in order to promote the progress of internal crosslinking.

  The obtained composite resin fine particles can be directly obtained as an aqueous dispersion or powdered particles by a general filtration / drying operation, but they are replaced with an organic solvent by an operation such as stripping, and non-aqueous fine particles are obtained. It can also be a dispersion.

Examples of the organic solvent include alcohols such as methanol, ethanol, n-propanol, isopropanol, n-butanol, and t-butanol;
Ethers such as diethyl ether, isopropyl ether, butyl ether, methyl cellosolve, tetrahydrofuran;
Examples include, but are not limited to, ketones such as acetone, methyl ethyl ketone, and diethyl ketone.

  The composite resin fine particles obtained in the present invention are characterized in that the amino resin (A) particles are coated with an acrylic resin (B) whose hydrophilicity and hydrophobicity are controlled, and an organic solvent or low polarity Good dispersibility even in binder resin.

The present invention will be described more specifically with reference to the following examples. However, the following examples do not limit the scope of rights of the present invention. In the examples, “part” represents “part by weight” and “%” represents “% by weight”.
Example 1
A reactor equipped with a stirrer, a reflux condenser, and a thermometer was charged with 0.2 part of N-methylolacrylamide, 0.8 part of methyl methacrylate, 1.0 part of N, N-dimethylacrylamide and 97 parts of water, and nitrogen gas was supplied. The flowing dissolved oxygen was removed. After heating the reactor to 60 ° C., 0.005 part of 2,2′-azobis (2-amidinopropane) dihydrochloride (Wako Pure Chemicals, V-50) dissolved in 1.0 part of ion-exchanged water was used. Added and allowed to react for 5 hours. The resulting acrylic resin aqueous solution was charged with 9.8 parts of melamine, 2.5 parts of benzoguanamine, 21.0 parts of 37% formalin aqueous solution, 45.6 parts of methanol, and 20 parts of ion-exchanged water, and the temperature was raised to 80 ° C. while stirring. Reacted for 30 minutes. After confirming that melamine was dissolved, 1.0 part of acetic acid was added and stirred at 80 ° C. for 3 hours to obtain a fine particle dispersion.
(Examples 2 to 5)
In the same manner as in Example 1, acrylic resin (B) and amino resin (A) were reacted with the composition shown in Table 1 to obtain a fine particle dispersion.

(Comparative Example 1)
A reactor equipped with a stirrer, a reflux condenser, and a thermometer was charged with 113 parts of 37% formalin solution, 600 parts of ion-exchanged water, and 63 parts of melamine, and the temperature was raised to 80 ° C. while stirring and reacted for 30 minutes. After confirming that melamine is dissolved, 59 parts of Snowtex OXS (Nissan Chemical Co., Ltd., SiO ₂ min 11.5%, particle size 4 nm, pH 3-4) as a dispersion stabilizer, followed by oxalic acid 20 A part dissolved in 100 parts of water was added and stirred at 80 ° C. for 3 hours to obtain a fine particle dispersion.

(Comparative Example 2)
In a reactor equipped with a stirrer, reflux condenser, and thermometer, 250 parts of melamine / formaldehyde initial condensate [Nihon Carbide Co., Ltd., Nical Resin S-260] and nonionic surfactant Emulgen 930 [manufactured by Kao Corporation] , Polyoxyethylene nonylphenyl ether] was added to 2340 parts of water, and the mixture was heated to 70 ° C. and dissolved while stirring. To this, 90 parts of a 5% dodecylbenzenesulfonic acid aqueous solution was added and stirred at 70 ° C. for 3 hours to obtain a fine particle dispersion.

  With respect to the resin fine particles obtained in Examples and Comparative Examples, physical properties and particle dispersibility in the resin were evaluated by the following methods.

(Evaluation of average particle size and coefficient of variation)
For the average particle size and coefficient of variation of the composite resin fine particles, an image obtained by observing the particles with an optical microscope (BX60 manufactured by OLYMPUS) was measured using image analysis / measurement software (Win Roof Standard Ver. 5.0 manufactured by Mitani Corporation). The particle diameter was actually measured and calculated.

(Evaluation of particle dispersibility in resin)
For evaluation of particle dispersibility in the resin, the resin fine particles obtained in Examples and Comparative Examples were centrifuged, and the precipitate was vacuum dried overnight at 80 ° C. and then pulverized. Further, the following solvent-based acrylic resin solution was used as the base resin.

(Preparation of solvent-based acrylic resin solution)
Put 800 parts of cyclohexanone in the reactor, heat to 100 ° C. while injecting nitrogen gas into the vessel, and drop the mixture of the following ethylenically unsaturated monomer and thermal polymerization initiator at the same temperature over 1 hour. A polymerization reaction was performed.
60.0 parts of styrene
Methacrylic acid 60.0 parts
Methyl methacrylate 65.0 parts
Butyl methacrylate 65.0 parts
Azobisisobutyronitrile 10.0 parts

  After the dropwise addition, the mixture was further reacted at 100 ° C. for 3 hours, then 2.0 parts of azobisisobutyronitrile dissolved in 50 parts of cyclohexanone was added, and the reaction was further continued at 100 ° C. for 1 hour. An acrylic resin solution having a molecular weight of about 40,000 was obtained. After cooling to room temperature, about 2 g of the resin solution was sampled, heated and dried at 180 ° C. for 20 minutes to measure the nonvolatile content, and cyclohexanone was added to the previously synthesized resin solution so that the nonvolatile content was 20 wt%. Thus, a solvent-based acrylic resin solution was prepared.

25 parts of the resulting solvent-based acrylic resin solution, 7 parts of trimethylolpropane triacrylate (NK ester ATMPT, manufactured by Shin-Nakamura Chemical Co., Ltd.), 10 parts of composite resin fine particles, 1.0 part of photoinitiator (Irgacure 907, manufactured by Ciba Geigy) Then, 57 parts of cyclohexanone was mixed, and the resulting resin coating solution was applied to a 100 mm × 100 mm × 1.1 mm glass plate with a spin coater, dried at 70 ° C. for 20 minutes, and integrated using an ultrahigh pressure mercury lamp. After UV exposure with a light amount of 150 mJ, heating was performed at 230 ° C. for 1 hour to prepare a coating film having a film thickness of “average particle diameter of particles + 1 μm”. The obtained coating film was visually evaluated and observed with an optical microscope (BX60 manufactured by OLYMPUS). Further, the surface roughness (Ra) was measured with Dektak 3030 (manufactured by Nippon Vacuum Technology). The obtained results are shown in Table 2. In addition, visual evaluation and microscopic observation were performed according to the following criteria.
○: “There are no visibly visible particles, and the particles are evenly dispersed even under microscopic observation.”
Δ: “There are no sights that can be visually confirmed, but aggregates are observed by microscopic observation.”
X: “There is a part that can be visually confirmed, and an agglomerate is seen even by microscopic observation.”

  As shown in Table 2, the composite resin fine particles of Examples 1 to 5 in which the particles of the amino resin (A) are coated with the acrylic resin (B) have good visual evaluation and observation results with an optical microscope, and have a rough surface. In contrast, the amino resin fine particles of Comparative Examples 1 and 2 were poor in both surface roughness and surface roughness, whereas the fine particle dispersibility in the solvent-based acrylic resin was good. The fine particle dispersibility in the acrylic resin was poor.

Claims (8)

Composite resin fine particles obtained by coating particles of amino resin (A) with acrylic resin (B),
The amino resin (A) is a resin obtained by addition-condensation reaction of a triazine ring-containing compound (a1) and an aldehyde compound (a2) capable of addition-condensation reaction with an aldehyde compound, and
The acrylic resin (B) comprises an ethylenically unsaturated monomer (b1) having a functional group capable of addition reaction with an aldehyde compound or a functional group capable of condensation or addition reaction with a methylol group, and an ethylenically unsaturated monomer having a dialkylamino group. A resin obtained by radical polymerization of an ethylenically unsaturated monomer containing a saturated monomer (b2) and an ethylenically unsaturated monomer (b3) having a solubility in water of 5% by weight or less. Composite resin fine particles characterized by that.   The composite resin fine particles according to claim 1, wherein the composite resin fine particles are obtained by addition condensation reaction of an acrylic resin (B), a triazine ring-containing compound (a1), and an aldehyde compound (a2) in an aqueous solvent.   The composite resin fine particles according to claim 1 or 2, wherein the ethylenically unsaturated monomer (b1) is at least one selected from acrylamide, 2-vinyl-4,6-diamino-s-triazine, and N-methylolacrylamide. .   The composite resin fine particle according to any one of claims 1 to 3, wherein the ethylenically unsaturated monomer (b2) is at least one selected from N, N-dimethylacrylamide and N, N-diethylacrylamide.   The acrylic resin (B) is 1 to 30% by weight of ethylenically unsaturated monomer (b1), 10 to 70% by weight of ethylenically unsaturated monomer (b2), and 0.1 to 75% by weight. The composite resin fine particles according to any one of claims 1 to 4, wherein the ethylenically unsaturated monomer (b3) is radically polymerized.   The composite resin fine particles according to claim 1, wherein the acrylic resin (B) is colloidal in an aqueous solvent.   The composite resin fine particles according to any one of claims 1 to 6, which have an average particle diameter of 0.01 to 20 µm and a coefficient of variation of the particle diameter of less than 20%. In an aqueous solvent, an ethylenically unsaturated monomer (b1) having a functional group capable of addition reaction with an aldehyde compound or a functional group capable of condensation or addition reaction with a methylol group, and an ethylenically unsaturated monomer having a dialkylamino group An acrylic resin (B) obtained by radical polymerization of an ethylenically unsaturated monomer (b2) and an ethylenically unsaturated monomer (b3) having a solubility in water of 5% by weight or less. A first step of obtaining
A composite resin fine particle comprising: the acrylic resin (B), a triazine ring-containing compound (a1) capable of addition condensation with an aldehyde compound, and a second step of addition condensation reaction of the aldehyde compound (a2). Production method.