JP2003176330A - Amino resin particle and method for producing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide new amino resin particles excellent in affinity for organic media, resins, metals, etc. <P>SOLUTION: The amino resin particles comprise an amino resin consisting essentially of a structural unit derived from a hydroxyalkylmelamine having a ≥2C hydroxyalkyl group and/or a structural unit derived from a condensation product of the hydroxyalkylmelamine with formaldehyde and have an unsmooth particle surface. This method for producing the amino resin particles comprises obtaining amino resin particles in which the particle surface is unsmooth by condensing and curing a raw material compound containing a condensation product of the hydroxyalkylmelamine having the ≥2C hydroxyalkyl group in the presence of an acidic catalyst. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to amino resin particles and a method for producing the same. More specifically, for example, a slipperiness improving agent for plastic films and sheets, an antiblocking agent, a matte finishing agent for paints, a light diffusing agent,
It is useful in various applications such as surface hardness improvers, spacers for liquid crystal display boards, conductive particles, standard particles for measurement and analysis, and acid dyes, basic dyes, fluorescent dyes and fluorescent dyes. The present invention relates to amino resin particles that can be used as a pigment for coloring paints, inks and plastics by coloring with various dyes such as whitening agents.

[0002]

2. Description of the Related Art Conventionally, as amino resin particles, particles made of a resin obtained by condensing and curing melamine or benzoguanamine after methylolation with formaldehyde, and mechanical strength and solvent resistance are well known. ,
It is known to be used for various applications as described above because it has excellent heat resistance, chemical resistance, etc. and is easily charged positively. However, in most conventional amino resin particles, the surface of the particle is almost entirely smooth and almost spherical.For example, when used in applications such as films and paints mixed with an organic medium, the particles fall off after use. In addition, when the particle surface is coated with a resin or a metal, the coating often peels off, and the poor affinity between the organic medium and the resin or metal with the amino resin particles causes a problem. Was becoming. Until now,
In order to solve such a problem, attempts have been made to improve the surface of amino resin particles and to increase the chemical affinity, but they have not been sufficiently resolved, and new amino resin particles and their Development of methods is desired. On the other hand, as a physical method for obtaining the anchor effect on the particle surface, it is possible to obtain particles by crushing, but when crushing, various particles from coarse particles to fine particles are generated, and classification operation is indispensable. It is not preferable from the viewpoint of cost and cost, and there is too much variation in shape.

[0003]

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a novel amino resin particle excellent in affinity with an organic medium, resin, metal and the like, and a method for producing the same. is there.

[0004]

Means for Solving the Problems The inventors of the present invention have made extensive studies to solve the above problems. As a result, as a means for increasing the affinity of the amino resin particles described above, by physically modifying the surface, not by modifying the particle surface from the viewpoint of improving the chemical affinity as has been done conventionally. I thought it would be better to improve the affinity. That is, by increasing the specific surface area of the particles by making the surface of the amino resin particles, which was almost smooth in the past, non-smooth,
I thought that if the so-called anchor effect was enhanced, the affinity could be improved.

As a result of repeated studies and trial and error based on such knowledge, it was obtained by essentially using a hydroxyalkylmelamine having a hydroxyalkyl group having 2 or more carbon atoms as a raw material for synthesizing amino resin particles, In the case of a novel amino resin particle and a method for producing the same, the structural unit derived from the hydroxyalkyl melamine and the structural unit derived from the condensate of the hydroxyalkyl melamine and formaldehyde are wrinkled. The present invention has been completed, and it has been confirmed that the above problems can be solved all at once, and the present invention has been completed. That is, the amino resin particle according to the present invention has a structural unit derived from hydroxyalkylmelamine (where the hydroxyalkyl group has 2 or more carbon atoms), and /
Alternatively, the particles are composed of an amino resin that essentially contains a structural unit derived from the condensate of the hydroxyalkyl melamine and formaldehyde, and the particle surface is non-smooth.

The method for producing amino resin particles according to the present invention is a hydroxyalkyl melamine (provided that the hydroxyalkyl group has 2 or more carbon atoms), and / or
Alternatively, the raw material compound containing the condensate of hydroxyalkylmelamine and formaldehyde is condensation-cured in the presence of an acidic catalyst to obtain amino resin particles having a non-smooth particle surface.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The amino resin particles according to the present invention and the method for producing the same will be specifically described below, but the scope of the present invention is not restricted by these descriptions, and the following examples are given. Other than the above, appropriate implementation is possible within the range that does not impair the gist of the present invention. The amino resin particles according to the present invention (hereinafter sometimes referred to as the amino resin particles of the present invention) are structural units derived from hydroxyalkyl melamine (provided that the hydroxyalkyl group has 2 or more carbon atoms), and / Alternatively, the particles are composed of an amino resin that essentially includes a structural unit derived from the condensate of the hydroxyalkyl melamine and formaldehyde, and the particle surface is non-smooth.

The hydroxyalkylmelamine referred to in the present invention is represented by the following structural formula (1):

[0009]

[Chemical 1]

(Wherein R represents a hydrogen atom or a hydroxyalkyl group having 2 or more carbon atoms, at least one of which is a hydroxyalkyl group having 2 or more carbon atoms). is there. The hydroxyalkyl group is not particularly limited as long as it is a group in which at least one hydrogen atom in an alkyl group having 2 or more carbon atoms is replaced with a hydroxyl group, and specifically, for example, the following formula (2 ): — (CH ₂ ) _n OH (2) (In the formula, n represents an integer of 2 or more). The number of carbon atoms of the hydroxyalkyl group (for example, in the formula (2), n represents the number of carbon atoms of the hydroxyalkyl group) is not particularly limited as long as it is 2 or more, but preferably 2 to 6 carbon atoms. Yes, and most preferably has 4 carbon atoms. When the number of carbon atoms is 2 or more, the particle surface of the resulting amino resin particles can be made non-smooth and the specific surface area can be increased. Therefore, by using the so-called anchor effect, it can be used by mixing with other organic media. Or the affinity of the amino resin particles when a resin or metal coating layer is provided on the surface of the particles can be improved.

In the hydroxyalkylmelamine represented by the above structural formula (1), R is hydrogen or a hydroxyalkyl group having 2 or more carbon atoms as described above, and 3 in the structural formula (1).
R in the existing —NR ₂ group (ie, structural formula (1)
It is necessary that at least one R out of the six R) present in the formula is a hydroxyalkyl group, and above all, the hydroxyalkylmelamine represented by the structural formula (1) is
When all the three —NR ₂ groups in the structural formula (1) are —NHR groups and at least one R out of the three existing R is the hydroxyalkyl group (that is, specifically Is preferably mono (hydroxyalkyl) melamine, bis (hydroxyalkyl) melamine or tris (hydroxyalkyl) melamine). These may be the case where only one type is used,
It may be a case where two or more kinds are used in combination.

The hydroxyalkyl melamine is not particularly limited, but specifically, for example, mono (hydroxyethyl) melamine, mono (hydroxypropyl) melamine, mono (hydroxybutyl) melamine,
Mono (hydroxypentyl) melamine, mono (hydroxyhexyl) melamine, mono (hydroxyheptyl) melamine, mono (hydroxyoctyl) melamine, mono (hydroxynonyl) melamine, mono (hydroxydecyl) melamine, mono (hydroxydodecyl) melamine,
Bis (hydroxyethyl) melamine, bis (hydroxypropyl) melamine, bis (hydroxybutyl) melamine, bis (hydroxypentyl) melamine, bis (hydroxyhexyl) melamine, bis (hydroxyheptyl) melamine, bis (hydroxyoctyl) melamine,
Bis (hydroxynonyl) melamine, bis (hydroxydecyl) melamine, bis (hydroxydodecyl) melamine, tris (hydroxyethyl) melamine, tris (hydroxypropyl) melamine, tris (hydroxybutyl) melamine, tris (hydroxypentyl) melamine, tris Preferable examples include (hydroxyhexyl) melamine, tris (hydroxyheptyl) melamine, tris (hydroxyoctyl) melamine, tris (hydroxynonyl) melamine, tris (hydroxydecyl) melamine, tris (hydroxydodecyl) melamine. It should be noted that the hydroxyalkyl groups in the above-listed groups include those having one hydroxyl group and those having two or more hydroxyl groups. These may be used alone or in combination of two or more. Among them, monohydroxybutyl melamine, bishydroxybutyl melamine and trishydroxybutyl melamine are more preferable.

The condensate of hydroxyalkylmelamine and formaldehyde as used in the present invention is a compound in which the amino group of hydroxyalkylmelamine is methylolated with formaldehyde by reacting hydroxyalkylmelamine with formaldehyde. This methylolated product is generally referred to as a condensate of hydroxyalkylmelamine and formaldehyde (specifically, an initial condensate, preferably a water-affinitive initial condensate), which serves as a precursor of an amino resin. The details of the hydroxyalkylmelamine used for obtaining the condensate are preferably the same as the above-mentioned hydroxyalkylmelamine in the present invention, but more specifically, the hydroxyalkylmelamine represented by the general formula (1) above. In, it is necessary that at least one R is a hydrogen atom. This is because there is no amino group for methylolation with formaldehyde.

The formaldehyde mentioned above is not particularly limited, but specific examples thereof include those generating formaldehyde such as formalin, trioxane and paraformaldehyde.
The amino resin particles of the present invention are particles of an amino resin obtained by subjecting a raw material compound containing the hydroxyalkyl melamine and / or the condensate to a condensation / curing reaction, and particles of a resin having a structural unit derived from the raw material compound. Can be. In the amino resin particles of the present invention, the total content of the structural units derived from the hydroxyalkylmelamine and / or the structural units derived from the condensate in the entire resin particles is preferably 40% by weight or more, more preferably Is 70% by weight or more, and even more preferably 90% by weight or more. When the total content ratio is less than 40% by weight, it may not be non-smooth, which is not preferable.

In the amino resin particles of the present invention, in addition to the structural unit derived from the hydroxyalkyl melamine and / or the structural unit derived from the condensate, other amino resin particles for constituting the amino resin particles may be added, if necessary. It may have a structural unit derived from a raw material compound. Other raw material compounds are not particularly limited, but specifically,
For example, benzoguanamine, cyclohexanecarboguanamine, cyclohexenecarboguanamine, melamine,
Acetoguanamine, norbornene carboguanamine, paratoluene sulfonamide, benzoguanamine (2,4
-Diamino-6-phenyl-sym. -Triazine) and a condensation product of formaldehyde with any one of a group of amino compounds consisting of urea (specifically, an initial condensation product,
Preferred is a water-affinitive initial condensate). The formaldehyde is preferably the same as those detailed above.

The amino resin particles of the present invention have a non-smooth resin particle surface because the amino resin has the above-mentioned structural unit. The non-smooth particle surface is not particularly limited, but specifically,
For example, the particle surface has wrinkles partially or wholly, at least a part of the particle surface has local irregularities, the particle surface has a soccer ball or golf ball shape, the particle surface has a plurality of A preferred form is a polyhedron composed of planes, and among them, a form having wrinkles entirely on the particle surface is more preferred. Also,
The confirmation of these non-smooth particle surface morphologies can be observed with, for example, a scanning electron microscope (SEM),
In the present invention, when it can be confirmed by scanning electron microscope (SEM) that one particle as a whole has wrinkles, irregularities, protrusions or the like on the surface of the particle under a magnification that can be observed in one visual field, It is assumed that particles having wrinkles have a non-smooth particle surface.

The method for producing amino resin particles according to the present invention (hereinafter sometimes referred to as the method for producing amino resin particles of the present invention or the production method of the present invention) is a hydroxyalkyl melamine (provided that the hydroxyalkyl group is And / or a condensate of the hydroxyalkyl melamine and formaldehyde, in the presence of an acidic catalyst for condensation curing, whereby the particle surface is non-smooth. It is a method of obtaining a simple amino resin particle. The hydroxyalkyl melamine that is the raw material compound is not particularly limited,
Specifically, it is preferably the same as the hydroxyalkylmelamine described in the description of the amino resin particles of the present invention. Of these, hydroxybutyl melamine is more preferable.

The condensate of hydroxyalkylmelamine and formaldehyde, which are the above-mentioned raw material compounds, is not particularly limited, but specifically, the condensate of hydroxyalkylmelamine and formaldehyde described in the description of the amino resin particles of the present invention is used. It is preferably the same as the condensate. Of these, a condensate of hydroxybutyl melamine and formaldehyde is more preferable. The raw material compound referred to in the production method of the present invention may have other raw material compounds for obtaining amino resin particles, if necessary, in addition to the above-mentioned hydroxyalkylmelamine and / or the above condensate. .

The other raw material compound is not particularly limited, but specifically, it is preferably the same as the other raw material compound described in the description of the amino resin particles of the present invention. That is, a condensate (specifically, an initial condensate, preferably a water-affinitive initial condensate) of formaldehyde and any one of a group of amino compounds consisting of various amino compounds is preferably exemplified. In obtaining the amino resin particles of the present invention, a reaction process until obtaining the condensate, that is, the condensate referred to in the production method of the present invention (including condensates as other raw material compounds, if necessary),
The condensate obtained from the reaction process and / or the reaction process until finally obtaining the amino resin particles of the present invention using the hydroxyalkylmelamine will be described separately. The condensate is preferably a water-affinity initial condensate (water-affinity initial condensate), and the same applies below, but unless otherwise specified, the condensate, the initial condensate, and It shall be handled in the same manner as the water-affinity initial condensate.

In the reaction process until the condensate is obtained, the amino compound to be reacted with the formaldehyde may include the condensate as another raw material compound as the condensate, and therefore, the hydroxyalkylmelamine. In addition to the above, other amino compounds may be used together, but in that case, it is preferable that 40 to 100% by weight of the entire amino compound used is the hydroxyalkylmelamine. Among the amino compounds other than the hydroxyalkyl melamine, at least one selected from the group consisting of benzoguanamine, cyclohexanecarboguanamine, cyclohexenecarboguanamine and melamine among the above listed compounds,
Spherical particles are more easily obtained, and benzoguanamine and / or melamine are more preferable.

The formaldehyde is not particularly limited, but specifically, it may be one that generates formaldehyde such as formalin, trioxane and paraformaldehyde, like the one described in the description of the amino resin particles of the present invention. Preferred. When reacting an amino compound containing hydroxyalkylmelamine with formaldehyde, water is usually used as a solvent, so the method of adding formaldehyde is not particularly limited, but specifically, for example, formalin (aqueous solution). And the method of adding trioxane or paraformaldehyde to a solvent to generate formaldehyde in the reaction solution.

The molar ratio at the time of reacting the amino compound containing hydroxyalkylmelamine and formaldehyde is not particularly limited, but specifically, the formaldehyde is 2 to 4 mol per mol of the amino compound. It is preferably, and more preferably 2-3 mol. If the proportion of formaldehyde is out of the above range, the amount of amino compounds or unreacted formaldehyde may increase. The concentration of the amino compound and formaldehyde charged to water in the reaction solvent is preferably higher as long as the reaction is not hindered.
When the amino compound containing hydroxyalkylmelamine is reacted with formaldehyde, the pH of the reaction solution is
For example, it is preferable to adjust to neutral or weakly basic with sodium carbonate, sodium hydroxide, potassium hydroxide, aqueous ammonia and the like. The reaction temperature is not particularly limited, but is preferably 70 to 100 ° C., for example. And in this reaction, the viscosity of the reaction solution is
For example, it is preferable to terminate the reaction solution by performing an operation such as cooling the reaction solution at a time point of 2 × 10 ^{−2 to} 5.5 × 10 ⁻² Pa · s. As a result, a reaction liquid containing the condensate is obtained. Therefore, the reaction time is not particularly limited. By setting the viscosity of the reaction solution to the above viscosity, it is possible to obtain resin particles having a narrow particle size distribution. Also, the smaller the viscosity of the reaction solution,
The particle size of the produced amino resin particles tends to be small. Since the viscosity of the reaction liquid at the end of the reaction is significantly higher than the viscosity of the aqueous solution (at the start of the reaction) after charging the amino compound containing hydroxyalkylmelamine and formaldehyde, It is hardly affected by the concentration.

For the water-affinity precondensate which is the preferred form of the above condensate, the degree of water affinity is generally 2
Ratio (% by weight) of the amount of water dropped until water is turbid by adding water to the (initial) condensate at 5 ° C. with respect to the (initial) condensate
(Hereinafter, this value may be referred to as water miscibility.) The water miscibility is preferably 100% by weight.
It is above, more preferably 150% by weight or more, and even more preferably 200% by weight or more. When the water miscibility is less than 100% by weight, no matter how the (initial) condensate is dispersed in an aqueous solution containing a surfactant, only a non-uniform emulsion having a relatively large particle size is formed. This is not possible, and as a result, the variation in the particle diameter of the resin particles becomes large.

Next, in the reaction process until the amino resin particles are obtained by using the raw material compound containing the condensate and / or hydroxyalkylmelamine obtained in the above reaction process, the amino resin particles are, for example, It is preferably obtained by a method of condensation-curing the raw material compound in an aqueous solution containing a surfactant in the presence of an acidic catalyst. In addition, after producing an emulsion of a cured resin by this condensation curing, the cured resin is separated from the emulsion,
More preferably, it is obtained by drying. Specifically, in this reaction process, first, it is preferable to add an acidic catalyst to the above raw material compound to make it emulsify in an aqueous solution, and to add a surfactant and an acidic catalyst to make it emulsify in an aqueous solution. Is more preferable. At that time, it is preferable to maintain the mixture at room temperature to 250 ° C, preferably 40 to 200 ° C with stirring. The method of adding the surfactant and the acidic catalyst is not particularly limited, and may be, for example, a method of previously mixing the surfactant and the acidic catalyst in an aqueous solution and then adding the raw material compound, Alternatively, the raw material compound may be mixed in an aqueous solution and then the surfactant and the acidic catalyst may be added.

The above-mentioned aqueous solution is not particularly limited, but specifically, for example, water or a mixture of water and an organic solvent having a solubility in water of 5 parts by weight or more per 100 parts by weight of water. It is preferably a solution. The organic solvent is not particularly limited, but specifically, for example, acetone, methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, sec-butyl alcohol and tert-butyl alcohol. ,
These may be used alone or in combination of two or more.
The concentration of the raw material compound charged into the aqueous solution (solid content concentration) is preferably 1 to 60% by weight, more preferably 2 to 50% by weight, and even more preferably 3 to 3%.
It is 0% by weight. If the solid content concentration is less than 1% by weight, the productivity of the resin particles will be reduced, and if it exceeds 60% by weight, the obtained resin particles will be enlarged or the particles will aggregate. Since the particle size of the resin particles cannot be controlled, only resin particles having a wide particle size distribution can be obtained.

The above-mentioned acidic catalyst is not particularly limited, but specifically, for example, a sulfonic acid having an alkyl group is preferable, and other acid may be contained. When other acid is contained, it is not particularly limited as long as it is in the range of 1 to 10% by weight with respect to the sulfonic acid having an alkyl group. The amount of the acidic catalyst used is not particularly limited, but specifically, it is preferably 0.1 to 20 parts by weight, more preferably 0.5 to 100 parts by weight of the raw material compound. -10 parts by weight,
It is more preferably 1 to 5 parts by weight. If the amount used is less than 0.1 parts by weight, it takes a long time for the condensation effect,
A stable emulsion of the cured resin cannot be obtained, resulting in coagulated and coarsened particles, and when it exceeds 20 parts by weight, plasticization of the particles occurs and cohesive fusion between the particles easily occurs.

The sulfonic acid having an alkyl group is not particularly limited, but a sulfonic acid having an alkyl group having 5 to 20 carbon atoms, preferably 10 to 18 carbon atoms, etc. are preferably mentioned. Of these, alkylbenzene sulfonic acid is particularly preferable. These sulfonic acids having an alkyl group may be used alone or in combination of two or more. The alkylbenzene sulfonic acid is not particularly limited, but specifically, for example, has 7 to 2 carbon atoms.
0, preferably an alkylbenzene sulfonic acid having 10 to 18 carbon atoms. Such an alkylbenzene sulfonic acid is not particularly limited, but specifically, for example, decylbenzenesulfonic acid, dodecylbenzenesulfonic acid, tetradecylbenzenesulfonic acid, hexadecylbenzenesulfonic acid, octadecylbenzenesulfonic acid, etc. Preferred examples include: These may be used alone or in combination of two or more.

The above-mentioned other acids are not particularly limited, but specifically, for example, mineral acids such as hydrochloric acid, sulfuric acid and phosphoric acid: ammonium salts of these mineral acids; sulfamic acid; benzenesulfonic acid and paratoluene. Examples thereof include sulfonic acids such as sulfonic acid and paratoluenesulfonic acid amide; organic acids such as phthalic acid, benzoic acid, acetic acid, propionic acid, salicylic acid; and the like. These other acids are 1
You may use only 1 type and may use 2 or more types together. Among the above-mentioned other acids, mineral acids and sulfonic acids are more preferable, and hydrochloric acid, sulfuric acid and paratoluenesulfonic acid are even more preferable. The surfactant is not particularly limited, but specifically, for example, anionic surfactant, cationic surfactant, nonionic surfactant, amphoteric surfactant, polymer interface Examples thereof include activators and polymerizable surfactants having one or more polymerizable carbon-carbon unsaturated bonds in the molecule.

The amount of the surfactant used is not particularly limited, but is 0.01 to 100 parts by weight of the above-mentioned raw material compound.
It is preferably 10 parts by weight. If the amount used is 0.
If the amount is less than 01 parts by weight, a stable emulsion cannot be obtained and 1
If it exceeds 0 parts by weight, spherical particles may not be formed.
According to the production method of the present invention, as described above, amino resin particles having a non-smooth particle surface can be obtained. The morphology of the non-smooth particle surface, the degree of non-smoothness, etc. are preferably the same as those described in the description of the amino resin particles of the present invention.

The amino resin particles obtained as described above may be further condensation-cured. The conditions for further condensation curing are not particularly limited, but in general, it is preferable to raise the temperature to 90 ° C. or higher and maintain it for a certain period of time. In addition, when the temperature is higher than the boiling point of the aqueous solution, it is necessary to perform it in a closed container such as an autoclave. In that case, the above-mentioned acidic catalyst such as sulfonic acid having an alkyl group may be used.
Further, the obtained amino resin particles may be used as colored particles. In that case, it is preferable to carry out the condensation curing in a state where a dye is contained in the reaction system (in an aqueous solution).

The above-mentioned dye is not particularly limited, but specifically, an acid dye, a basic dye, a fluorescent dye, a fluorescent whitening agent, etc. are preferable, and among them, the acid dye is easily fixed in the particles. Therefore, it is more preferable. From the emulsion of the amino resin particles after the reaction, in order to separate and dry the amino resin particles, a conventionally known method may be used. Examples of the separation include a natural sedimentation method or a centrifugal sedimentation method and decantation. There are various separation methods such as separation by filtration and separation by filtration, and examples of the drying include various drying methods such as natural drying, reduced pressure drying and hot air drying. Further, prior to the separation, a flocculant such as aluminum sulfate may be added to accelerate the separation. The amino resin obtained by the above separation and drying can be crushed with a very light force such as a ball mill.

The average particle diameter of the obtained amino resin particles is not particularly limited, but it may be adjusted to about 0.5 to 50 μm, and more preferably 1.0 to 40.
μm, and even more preferably 1.5 to 30 μm. In the method for producing amino resin particles of the present invention,
Although not particularly limited, after the amino resin particles are obtained through the above reaction process, the obtained amino resin particles may be further purified and classified, which is preferable. In other words, removing impurities other than the desired amino resin particles,
It is preferable to make the size of the amino resin particles uniform to a desired degree.

Regarding the above-mentioned purification, the method is not particularly limited, but a method of obtaining only the amino resin particles by a usual filtration method using a filter paper, a method of discarding the supernatant other than the amino resin particles by decantation, etc. ,
It is preferable because it is convenient. Regarding the classification, the method is not particularly limited, and may be wet classification performed in a state where the amino resin particles are dispersed in a solvent or dry classification. The device for classification is not particularly limited, but for example, a cyclone, a sedimentation tower, or
A sieve or the like is preferably used. It should be noted that the sieve is one that classifies by passing whether or not it passes through a certain opening. For example, a sieve with a fine wire is used for an opening of 10 μm or more, for example, an opening of 20 μm or less. Is a metal foil or the like with fine holes made by etching, or a screen called rectangular screen with rectangular holes, which is called electro-sieve.
These have much better openings than the fine wire knitted sieve and can improve the classification accuracy. In particular, the electro-sieve is an excellent sieve with a smaller cross-sectional shape than the one with holes formed by etching, and it is possible to make holes smaller than the thickness. It is particularly preferable to carry out classification. Hereinafter, the electro-sieve will be described in detail.

The above electroformed sieve is a screen having a rectangular hole formed by plating. As a method for creating an electro-sieve, a conductive coating is formed on a glass plate that has been highly accurately corroded in a cross-line shape by physical plating such as vacuum deposition or sputtering, or chemical plating such as electrolytic plating or electroless plating. After that, the plating layer other than the groove in the corroded portion is removed, a mesh is formed on the plating layer by a method such as electrolytic plating, and the mesh is peeled from the original glass plate. The thus-prepared mesh may be further subjected to electrolytic plating after peeling from the original glass plate, if necessary. Further, as another production method, vacuum deposition on a glass flat plate, physical plating such as sputtering, or electrolytic plating, a conductive coating is formed by chemical plating such as electroless plating, and after applying a resist on the coating, There is also a method in which a pattern having a predetermined shape is formed, then a portion other than the pattern is removed by etching, and after peeling from the original glass plate, electrolytic plating is performed.

Materials for the electro-sieve include gold, platinum,
Silver, copper, iron, aluminum, nickel and various alloys based on these are used, but the durability of the sieve,
A material containing nickel as a main component is particularly preferably used in view of corrosion resistance and easiness of plating work. Electroforming sieve not only allows easy adjustment of the opening diameter and the number of openings per unit, but also has a very good distribution of opening diameters, so when used as a sieve, it is possible to classify very accurately. Becomes Since the electro-sieve is very thin, it may be easily damaged or torn, and metal-based impurities may be mixed into the classified particles. Especially when the classified adhesive spacer is used for an electronic device such as a liquid crystal display, the inclusion of metal impurities is a serious problem because it causes deterioration of quality and reliability. In order to avoid this problem, it is preferable to provide a grid-shaped or ring-shaped support on one or both sides of the electroformed sieve to increase the strength.

Regarding the attachment of the electro-sieve to the classifier, especially when ultrasonic vibration is applied, the electro-sifter and the classifier are rubbed with each other to damage the electro-sifter and metal particles are added to the classified particles. Since there is a risk of mixing, it is preferable to attach via a member made of an elastomer. In the classification using an electro-sieve, it is preferable to carry out the classification by a wet method by passing the particle dispersion through a classification device equipped with an electro-sieve. Compared to the dry method using an inert gas or air as a medium, the wet method has higher ultrasonic irradiation efficiency and higher dispersion stability,
In addition, particles are less attached to the electro-sieve. In particular, an adhesive spacer for a liquid crystal display device or the like having a small particle size generally has a strong cohesive force, so that the dispersion may be insufficient by the dry method. In the above wet method, as the liquid medium in which the particles are dispersed, the material of the electro-sieve used, the pore size,
It can be appropriately selected depending on the number of lines and the properties of particles or particle size distribution. Also, when classifying,
When the ultrasonic wave irradiation tip is inserted in the classification device, the efficiency of classification can be preferably improved by applying ultrasonic wave to a liquid medium such as water.

In the above classification, the amino resin particles are
The average particle size is preferably adjusted to 0.5 to 50 μm, more preferably 1.0 to 40 μm, and even more preferably 1.5 to 30 μm. Similarly, for the particle size distribution, the coefficient of variation is preferably 1 to 50%, more preferably 2 to 40%, and even more preferably 2 to 30%. When the classification is wet classification, the amino resin particles after classification are isolated. The method for isolation is not particularly limited, but examples thereof include centrifugation, decantation, and the method of evaporating the solvent.

The use of the amino resin particles of the present invention and the amino resin particles obtained by the production method of the present invention are not particularly limited, but specifically, for example, a plastic film Various improvers such as sheet slipperiness improvers, antiblocking agents, matte finishes for paints, light diffusers, surface hardness improvers, etc.,
It is useful for various applications such as spacers for liquid crystal display boards, conductive particles, and standard particles for measurement and analysis.
By coloring with various dyes such as basic dyes, fluorescent dyes and fluorescent whitening agents, they can be used as paints, pigments for coloring inks and plastics, and colored spacers for liquid crystal display panels.

[0039]

EXAMPLES The present invention will be described in more detail below with reference to examples, but the present invention is not limited thereto. In the following, "parts by weight" may be simply referred to as "parts" for convenience. -Example 1-Hydroxybutyl melamine (mono,
Mixture of bis form and tris form) 150 parts, concentration 37%
238 parts of formaldehyde and 1.07 parts of a 10% aqueous sodium carbonate solution were added to prepare a mixture. The mixture was heated to 85 ° C. with stirring to carry out polymerization to obtain an initial condensate. Separately, 5.5 parts of nonionic surfactant Emulgen 430 (manufactured by Kao, polyoxyethylene oleyl ether) was dissolved in 2455 parts of water, and the temperature of this surfactant aqueous solution was raised to 50 ° C. and stirred. did. The above-mentioned initial condensate was added to a surfactant aqueous solution under stirring to obtain an emulsion of the initial condensate. To this, 90 parts of a 5% aqueous solution of dodecylbenzene sulfonic acid was added,
It was kept at a temperature of ° C for 3 hours for condensation curing to obtain an emulsion of a cured resin. This emulsion was poured into 3000 parts of cold water and rapidly cooled. Then, a paste obtained by separating the cured resin from the emulsion by sedimentation was added to an aqueous solution obtained by dissolving 7.5 parts of Emulgen 430 and 4.5 parts of dodecylbenzenesulfonic acid in 2000 parts of water, Dispersion was performed using an ultrasonic disperser. The emulsion obtained by dispersion was gradually heated to 90 ° C., held for 1 hour, and then rapidly cooled. The cured resin was precipitated and separated from this emulsion to obtain cured fine particles of hydroxybutyl melamine / formaldehyde amino resin.

50 g of cured spherical fine particles of the above amino resin,
450 g of water and 0.5 g of CANITAT A (manufactured by Nitto Riken Co., Ltd.), which is a latent curing catalyst for amino resin, were charged into a 2 liter autoclave. After purging with nitrogen, 17
The temperature was raised to 0 ° C. and heat and pressure treatment was performed for 3 hours. After this treatment, the particles were separated by filtration, washed several times with pure water, dried at 160 ° C. for 4 hours and crushed to obtain the amino resin particles of Example 1 (hereinafter referred to as amino resin particles (1)). There is). When the particle size distribution of the obtained amino resin particles (1) was measured with a particle size distribution analyzer (manufactured by Coulter, Coulter Multisizer), the average particle size was 2.5 μm and the coefficient of variation was 8.0%. Further, the amino resin particles (1) were observed with a scanning electron microscope (SEM) (magnification: 100).
However, the whole particle surface was wrinkled.

-Example 2-In the same manner as in Example 1 except that formaldehyde was not used, the amino resin particles of Example 2 (hereinafter referred to as amino resin particles (2)) were used. Sometimes referred to as). Obtained amino resin particles (2)
The particle size distribution was measured by a particle size distribution measuring device (Coulter Multisizer, manufactured by Coulter Co.), and the average particle size was 2.0 μm and the coefficient of variation was 12.0%. When the amino resin particles (2) were observed with a scanning electron microscope (SEM) (magnification: 10,000 times), the entire particle surface was wrinkled.

Comparative Example 1 The same procedure as in Example 1 was carried out except that melamine was used instead of hydroxybutyl melamine in Example 1, and the amino resin particles of Comparative Example 1 (hereinafter, comparative amino resin particles) were used. (1) is sometimes obtained. The particle size distribution of the obtained comparative amino resin particles (1) was measured by a particle size distribution measuring device (Coulter Multisizer, manufactured by Coulter Co.). The average particle size was 2.2 μm, and the coefficient of variation was 10.0.
%Met. Further, the comparative amino resin particles (1) were observed with a scanning electron microscope (SEM) (magnification: 10000).
However, the particle surface was smooth and spherical.

[0043]

According to the present invention, the anchor effect of the particles themselves is improved by making the surface of the particles non-smooth and increasing their specific surface area. As a result,
It is possible to provide a novel amino resin particle which has excellent affinity with an organic medium, a resin, a metal and the like and can sufficiently exhibit excellent performance as an amino resin particle in various applications, and a method for producing the same.

Claims (4)

[Claims] 1. A structural unit derived from a hydroxyalkyl melamine (provided that the hydroxyalkyl group has 2 or more carbon atoms) and / or a structural unit derived from a condensate of the hydroxyalkyl melamine and formaldehyde is essential. Amino resin particles, which are particles composed of an amino resin and have a non-smooth particle surface. 2. The amino resin particle according to claim 1, which is non-smooth due to having wrinkles on the surface of the particle. 3. The amino resin particle according to claim 1, wherein the hydroxyalkyl melamine is hydroxybutyl melamine. 4. A raw material compound containing a hydroxyalkylmelamine (wherein the hydroxyalkyl group has 2 or more carbon atoms) and / or the condensate of the hydroxyalkylmelamine and formaldehyde in the presence of an acidic catalyst. A method for producing amino resin particles, the method comprising obtaining amino resin particles having a non-smooth particle surface by condensation curing.