JP2004123845A - Method for producing colored amino resin cross-linked particle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing colored amino resin cross-linked particles, comprising adding inorganic particles, when a water-soluble dye is added to an emulsion before the curing reaction to obtain the colored amino acid resin cured particles, by which the excellent disintegration property of the resin can sufficiently be exhibited. <P>SOLUTION: This method for producing the colored amino resin cross-linked particles, comprising reacting an amino compound with formaldehyde, emulsifying the obtained amino resin precursor, adding the water-soluble dye to the obtained emulsion, and then adding a catalyst to color and cure the amino acid precursor, is characterized by adding the inorganic particles to the emulsion after the addition of the catalyst. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for producing crosslinked amino resin particles by reacting an amino compound with formaldehyde. More specifically, the present invention relates to a method for producing crosslinked amino resin particles, in which a water-soluble dye is added to an emulsion before a curing reaction to obtain colored crosslinked particles.
[0002]
[Prior art]
Colored amino resin cross-linked particles, so-called amino resin cross-linked particles, are, for example, thermoplastic resins such as polypropylene, polyethylene, polystyrene and ABS; plastics such as thermosetting resins; printing inks, paints and printing as coloring agents. It is known to be suitably used for pigments such as;
Conventionally, it is known that amino resin colored crosslinked particles can be obtained by using various methods (for example, see Patent Documents 1 and 2). Specifically, for example, an amino compound is reacted with formaldehyde to obtain an amino resin precursor, and the amino resin precursor is emulsified to obtain an emulsion, and then a curing catalyst is added to the emulsion. In a general method for preparing amino resin crosslinked particles, in which an amino resin precursor in an emulsion state is cured, a method of adding an oil-soluble dye in a reaction for obtaining the amino resin precursor is well known. Have been. However, although it is preferable to use an oil-soluble dye because it can be easily and uniformly colored and high-quality colored particles can be obtained, it has an adverse effect on the human body at the time of production and environmental issues in recent years in the industrial world have been emphasized. In view of this tendency, it is naturally better to use a water-soluble dye while minimizing the use of an oil-soluble dye, and it is expected that the dye will be used more frequently in the future. Usually, when coloring with a water-soluble dye, the water-soluble dye is added to an emulsion in which the amino resin precursor is emulsified.
[0003]
On the other hand, in the production of general amino resin crosslinked particles, in order to efficiently prevent the finally obtained crosslinked particles from being firmly aggregated, silica is added to the emulsion before the curing reaction. It has been conventionally known that inorganic particles such as fine particles (specifically, inorganic compound particles) are added to form crosslinked particles having the inorganic particles adhered to the surface. This is because by adding inorganic particles to the amino resin precursor in an emulsion state in which the surface is soft, it is easier to adhere to the particle surface.
However, when obtaining amino resin crosslinked particles colored with a water-soluble dye as described above, the above-mentioned inorganic particles are added to at least the emulsion before the start of curing of the amino resin precursor to which the water-soluble dye has been added. Then, there is a problem that the amino resin precursor in an emulsified state is agglomerated so as not to be expected from the case where the water-soluble dye is not used, and the whole liquid rapidly thickens, and in some cases, In some cases, stirring or the like became impossible at all. Subsequently, even if a normal process such as a crosslinking reaction is performed, amino resin colored crosslinked particles that are strongly aggregated are necessarily obtained, and even if sufficient pulverization is performed by pressure or impact, etc. It was extremely difficult to obtain uniformly crushed colored particles without aggregation or the like.
[0004]
[Patent Document 1]
JP-A-49-57091
[0005]
[Patent Document 2]
JP-A-50-45852
[0006]
[Problems to be solved by the invention]
Therefore, a problem to be solved by the present invention is that when a water-soluble dye is used to produce amino resin colored crosslinked particles, amino resin particles can be prevented from inadvertent aggregation or the like. An object of the present invention is to provide a method for producing resin colored crosslinked particles.
[0007]
[Means for Solving the Problems]
The present inventor has conducted intensive studies in order to solve the above problems. In particular, the timing and order of addition of the water-soluble dye and the inorganic particles (inorganic compound particles) to be added to improve the disintegration properties were examined. As a result, instead of adding the inorganic particles to the emulsion containing the water-soluble dye before adding the catalyst for the curing reaction as in the prior art, after adding the above catalyst, that is, the amino resin Before starting the curing reaction of the particles, at least after starting the curing reaction, if the inorganic particles were added, it was confirmed that the above problem could be solved at once, and the present invention was completed. . As described above, conventionally, adding the inorganic particles to a place where the amino resin precursor before the curing reaction is in an emulsion state improves the crushability of the amino resin crosslinked particles after the curing reaction as much as possible. However, when the inorganic particles are added at this time, the above-described problems of aggregation and thickening of the emulsion become extremely remarkable when a water-soluble dye is used. In order to avoid this problem, the present inventor added a catalyst first and started curing the emulsified amino resin precursor surface, even if the adhesion of the inorganic particles might be slightly inferior. As a result, it is possible to easily solve the above-mentioned remarkable problems and to exert the effect of improving the crushability on the crosslinked particles after curing at a sufficiently satisfactory level. We found that we could do it.
[0008]
That is, the production method of the amino resin colored crosslinked particles according to the present invention,
Coloring the amino resin precursor by adding a water-soluble dye to an emulsion obtained by emulsifying an amino resin precursor obtained by reacting an amino compound with formaldehyde, and then adding a catalyst to the emulsion; A method for producing amino resin colored crosslinked particles by curing, wherein inorganic particles are added to the emulsion after the addition of the catalyst.
[0009]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, a method for producing the amino resin colored crosslinked particles according to the present invention will be described in detail, but the scope of the present invention is not limited to these descriptions, and does not impair the spirit of the present invention, other than the following examples. It can be carried out appropriately within the range.
In the present specification, the particle state in the production process of the amino resin colored crosslinked particles in the present invention is represented by two liquid states, “emulsion” and “suspension”. According to the usual definition, the term "emulsion" refers to a substance in which liquid particles are dispersed in a liquid as colloidal particles or coarser particles to form a milky state. In which solid particles are dispersed as colloidal particles or particles that can be seen with a microscope. Accordingly, in the production process of the amino resin colored crosslinked particles in the present invention, the state during emulsification may be expressed as an emulsion, and the state after curing may be expressed as a suspension. In addition, both forms may coexist during curing, but in this specification, the state during curing may be expressed as a suspension.
[0010]
The method for producing amino resin colored crosslinked particles according to the present invention comprises the steps of adding a water-soluble dye to an emulsion obtained by emulsifying an amino resin precursor obtained by reacting an amino compound with formaldehyde. A method for producing amino resin colored crosslinked particles by coloring and curing the amino resin precursor by adding a catalyst, wherein inorganic particles are added to the emulsion after the addition of the catalyst.
Hereinafter, a general method for producing amino resin colored crosslinked particles for carrying out the present invention will be described in detail, and the addition of inorganic particles, which is a feature of the production method of the present invention, and the timing thereof will also be described. I do.
[0011]
The production method of the present invention generally comprises a resinification step of obtaining an amino resin precursor by reacting an amino compound with formaldehyde, and emulsifying the amino resin precursor obtained in the resinification step. An emulsifying step of obtaining an emulsion of the amino resin precursor, a coloring step of adding a water-soluble dye to the emulsion obtained by the emulsifying step, and adding a catalyst to the emulsion after the coloring step to emulsify the emulsion. And a curing step of performing a curing reaction of the amino resin precursor to obtain crosslinked particles of the amino resin.
More specifically, after performing the above-mentioned curing reaction to obtain a suspension containing amino resin colored crosslinked particles, and further through a step of separating amino resin colored crosslinked particles from the suspension, amino resin colored crosslinked particles This is a production method for obtaining particles. In addition, the suspension containing the amino resin colored crosslinked particles can be used after being extracted from the reaction system and then optionally purified.
[0012]
In the resinification step, an amino-based compound is reacted with formaldehyde to obtain an amino resin precursor as an initial condensation reaction product. In reacting an amino compound with formaldehyde, water is usually used as a solvent. Therefore, as a reaction form, a method in which formaldehyde is converted into an aqueous solution (formalin) and an amino compound is added to cause a reaction, or trioxane or paraformaldehyde is added to water so that formaldehyde can be generated in water. A method in which an amino compound is added to an aqueous solution to cause a reaction, and the like, are preferably mentioned. Among them, the former method is more preferable in terms of economical efficiency, such as that an adjustment tank for a formaldehyde aqueous solution is not required and that it is easily available. .
[0013]
The form of the reaction between the amino compound and formaldehyde may be any form in which the amino compound and formaldehyde react in a mixed state.For example, in addition to the form in which the amino compound is added to an aqueous solution of formaldehyde, A form in which an aqueous solution of formaldehyde is added to the system compound may be used.
In general, it is preferable that the resinification step for performing the above reaction is performed under stirring by a generally known stirring device or the like.
The amino-based compound that can be used as a raw material in the resinification step is not particularly limited, but, for example, benzoguanamine (2,4-diamino-6-phenyl-sym.-triazine), cyclohexanecarboguanamine, cyclohexenecarboguanamine And melamine. Among them, amino compounds having a triazine ring are generally more preferable, but benzoguanamine has excellent dyeing properties in an initial condensation state because it has a benzene ring and two reactive groups, and can be used after crosslinking. It is particularly preferable because it has excellent flexibility (hardness), stain resistance, heat resistance, solvent resistance, and chemical resistance. These amino compounds may be used alone or in combination of two or more.
[0014]
In addition, the total of the amino compounds (benzoguanamine, cyclohexanecarboguanamine, cyclohexenecarboguanamine and melamine) exemplified above is preferably 40% by weight or more, more preferably 60% by weight or more, of all the amino compounds used. , More preferably 80% by weight or more, and most preferably 100% by weight. When the total of the amino compounds exemplified above is 40% by weight or more, an effect such that amino resin colored crosslinked particles excellent in heat resistance and solvent resistance can be obtained.
The molar ratio between the amino compound and formaldehyde (amino compound (mol) / formaldehyde (mol)) to be reacted in the resinification step is preferably 1 / 3.5 to 1 / 1.5, and 1/3. The ratio is more preferably 0.5 to 1 / 1.8, and even more preferably 1 / 3.2 to 1/2. If the molar ratio is less than 1 / 3.5, unreacted formaldehyde may increase, and if it exceeds 1 / 1.5, unreacted amino compound may increase.
[0015]
When water is used as a solvent, the amount of the amino compound and formaldehyde added to water, that is, the concentration of the amino compound and formaldehyde at the time of preparation should be higher as long as the reaction is not hindered. Is desirable. More specifically, the viscosity of the reaction solution containing the amino resin precursor as a reactant in a temperature range of 95 to 98 ° C. is set to 2 × 10 ^-2 ~ 5.5 × 10 ^-2 The concentration is preferably a concentration that can be adjusted and controlled within the range of Pa · s (20 to 55 cP), and more preferably, in the emulsification step described below, the concentration of the amino resin precursor in the emulsion is 30 to The concentration may be such that the reaction solution is added to the aqueous solution of the emulsifier or the concentration is such that the emulsifier or the aqueous solution of the emulsifier can be added to the reaction solution so as to be within the range of 60% by weight.
[0016]
Therefore, when a reaction solution containing an amino resin precursor is obtained in the resinification step, the viscosity of the reaction solution within the temperature range of 95 to 98 ° C. is 2 × 10 ^-2 ~ 5.5 × 10 ^-2 Pa · s (20-55 cP), more preferably 2.5 × 10 ^-2 ~ 5.5 × 10 ^-2 Pa · s (25 to 55 cP), more preferably 3.0 × 10 ^-2 ~ 5.5 × 10 ^-2 Pa · s (30 to 55 cP).
As the method for measuring the viscosity, a method using a viscometer is most suitable so that the progress of the reaction can be grasped immediately (in real time) and the end point of the reaction can be accurately determined. . As the viscometer, a vibrating viscometer (product name: MIVI 6001 manufactured by MIVI ITS Japan) can be used. This viscometer is provided with a vibrating part that constantly vibrates, and when the vibrating part is immersed in the reaction liquid, the viscosity of the reaction liquid increases and a load is applied to the vibrating part. Is immediately converted and displayed.
[0017]
By reacting an amino compound with formaldehyde in water, an amino resin precursor that is a so-called initial condensate can be obtained. The reaction temperature is preferably in the range of 95 to 98 ° C. so that the progress of the reaction can be immediately grasped and the end point of the reaction can be accurately determined. The reaction between the amino compound and formaldehyde has a viscosity of 2 × 10 ^-2 ~ 5.5 × 10 ^-2 At the point when the pressure falls within the range of Pa · s, the reaction may be terminated by performing an operation such as cooling the reaction solution. Thereby, a reaction solution containing the amino resin precursor is obtained. The reaction time is not particularly limited.
[0018]
Regarding the amino resin precursor obtained in the resinification step, the molar ratio of the structural unit derived from the amino compound and the structural unit derived from formaldehyde constituting the amino resin precursor (the structural unit derived from the amino compound (mol)) / Structural unit (mol) derived from formaldehyde) is preferably 1 / 3.5 to 1 / 1.5, more preferably 1 / 3.5 to 1 / 1.8, and 1/3. It is more preferable that the ratio is 0.2 to 1/2. By setting the molar ratio within the above range, particles having a narrow particle size distribution can be obtained.
Usually, the viscosity of the reaction solution at the end of the reaction is significantly higher than the viscosity of the aqueous solution (at the start of the reaction) in which the amino compound and formaldehyde are charged. Not affected. Amino resin precursor is usually soluble in organic solvents such as acetone, dioxane, methyl alcohol, ethyl alcohol, isopropyl alcohol, butyl alcohol, ethyl acetate, butyl acetate, methyl cellosolve, ethyl cellosolve, methyl ethyl ketone, toluene and xylene But is substantially insoluble in water.
[0019]
In the method for producing amino resin colored crosslinked particles of the present invention, the viscosity of the reaction liquid in the resinification step of obtaining a reaction liquid containing the amino resin precursor is reduced, so that the finally obtained amino resin colored crosslinked particles are obtained. The particle diameter of the particles can be reduced. However, the viscosity of the reaction solution is 2 × 10 ^-2 If less than Pa · s, or 5.5 × 10 ^-2 When it exceeds Pa · s, it is not possible to finally obtain amino resin colored crosslinked particles having a substantially uniform particle size (narrow particle size distribution). That is, the viscosity of the reaction solution is 2 × 10 ^-2 If it is less than Pa · s (20 cP), the stability of the emulsion obtained in the emulsification step described below will be poor. For this reason, when the amino resin precursor is cured in the curing step, the obtained amino resin colored crosslinked particles may be enlarged or the particles may be aggregated, and the particle diameter of the amino resin colored crosslinked particles may be reduced. It cannot be controlled and may result in amino resin colored crosslinked particles having a wide particle size distribution. In addition, when the stability of the emulsion is poor, the particle size (average particle size) of the amino-resin-colored crosslinked particles changes every time it is manufactured (for each batch), which may cause variations in the product. is there. On the other hand, the viscosity of the reaction solution was 5.5 × 10 ^-2 If the pressure exceeds Pa · s (55 cP), the load on the high-speed stirrer used in the emulsification step described below is too large, and the shearing force is reduced. Therefore, the reaction solution can be sufficiently stirred (emulsified). It may not be possible. For this reason, the particle diameter of the finally obtained crosslinked amino resin particles cannot be controlled, and there is a possibility that the crosslinked amino resin particles have a wide particle size distribution. Therefore, adjusting the reaction liquid in the resinization step to the above viscosity range is a preferred embodiment for obtaining the amino resin colored crosslinked particles of the present invention.
[0020]
In the emulsification step, the amino resin precursor obtained in the resinification step is emulsified to obtain an emulsion of the amino resin precursor. In emulsifying, for example, it is preferable to use an emulsifier capable of forming a protective colloid.
As the emulsifier, for example, polyvinyl alcohol, carboxymethyl cellulose, sodium alginate, polyacrylic acid, a water-soluble polyacrylate, polyvinylpyrrolidone and the like can be used. These emulsifiers may be used in the form of an aqueous solution in which the entire amount is dissolved in water, or a part of the emulsifier is used in the form of an aqueous solution, and the rest is used as it is (for example, in the form of powder, granule, liquid, etc.). You may do so. Among the emulsifiers exemplified above, polyvinyl alcohol is more preferable in consideration of the stability of the emulsion, the interaction with the catalyst, and the like. The polyvinyl alcohol may be completely saponified or partially saponified. The degree of polymerization of polyvinyl alcohol is not particularly limited. The larger the amount of the emulsifier used for the amino resin precursor obtained in the resinification step, the smaller the particle size of the generated particles tends to be. The amount of the emulsifier used is preferably 1 to 30 parts by weight, more preferably 1 to 5 parts by weight, based on 100 parts by weight of the amino resin precursor obtained in the resinification step. If the amount is outside the above range, the stability of the emulsion may be poor.
[0021]
In the emulsification step, for example, the reaction solution obtained in the resinification step was added to an aqueous solution of an emulsifier such that the concentration of the amino resin precursor (that is, the solid content concentration) was in the range of 30 to 60% by weight. Thereafter, the emulsion is preferably emulsified within a temperature range of 50 to 100 ° C, more preferably 60 to 100 ° C, and still more preferably 70 to 95 ° C. The concentration of the aqueous solution of the emulsifier is not particularly limited as long as the concentration of the amino resin precursor can be adjusted within the above range. When the concentration of the amino resin precursor is less than 30% by weight, the productivity of amino resin colored crosslinked particles may be reduced. When the concentration exceeds 60% by weight, the obtained amino resin colored crosslinked particles may be enlarged, The particles may aggregate, and the particle diameter of the amino resin colored crosslinked particles cannot be controlled. Therefore, the amino resin colored crosslinked particles may have a wide particle size distribution.
[0022]
As a stirring method in the emulsification step, a method using a device capable of stirring more strongly (a device having a high shearing force), specifically, for example, a so-called high-speed stirrer, a homomixer, a TK homomixer (special Kika Kogyo Co., Ltd.), high-speed disperser, Ebara Milser (Ebara Corporation), high-pressure homogenizer (Izumi Food Machinery Co., Ltd.), static mixer (Noritake Co., Ltd.), etc. The method is preferred.
In the emulsification step, it is preferable to promote the emulsification of the amino resin precursor obtained in the resinification step until the amino resin precursor has a predetermined particle diameter, and the predetermined particle diameter is an amino resin having a finally desired particle diameter. What is necessary is just to set suitably so that a colored crosslinked particle is obtained. Specifically, emulsification is performed so that the average particle diameter of the emulsified amino resin precursor becomes 0.1 to 30 μm by appropriately considering the type of the container and the stirring blade, the stirring speed, the stirring time, the emulsification temperature, and the like. Preferably, it is more preferably 0.5 to 25 μm, and still more preferably 0.5 to 20 μm. By emulsifying the amino resin precursor so as to have the above particle size range, amino resin colored crosslinked particles having a desired particle size range described later can be finally obtained.
[0023]
The average particle size of the emulsified amino resin precursor (average particle size of the amino resin precursor dispersed in the emulsion obtained by emulsification) was measured using a Coulter Multisizer II described in Examples described later. It is the value measured by The present invention can further include a step of adding water to the emulsion obtained through the above emulsification step to dilute the emulsion. In general, when performing a curing step described below, it is necessary to temporarily lower the liquid temperature of the emulsion obtained after emulsification to a temperature suitable for initiating the curing reaction. In the case of a turbid liquid, the viscosity of the liquid suddenly rises, so that the emulsified amino resin precursor (emulsion particles) is destroyed, or the emulsion particles fuse to form a large variation in the particle size distribution. There are problems such as occurrence. Such problems can be easily solved by adding water to the emulsion and diluting it. Furthermore, since the temperature of the emulsion can be easily lowered at the same time as the dilution, the temperature can be easily lowered to a desired temperature at the time of performing the curing reaction. In the present invention, the average particle size of the emulsified amino resin precursor (dispersed in the emulsion obtained by emulsification) is used as a form showing the state of the emulsion before dilution obtained through the emulsification step. Average particle size of the amino resin precursor). In the present invention, when performing the step of adding water to the emulsion obtained through the emulsification step and diluting the water, when the average particle diameter of the emulsified amino resin precursor becomes 0.1 to 30 μm, Is preferable, and water is added to dilute when it becomes 0.5 to 25 μm, more preferably 0.5 to 20 μm.
[0024]
In the coloring step, the emulsified amino resin precursor is colored by adding a water-soluble dye to the emulsion obtained in the emulsifying step.
As the water-soluble dye, any conventionally known dye which is water-soluble, that is, can be dissolved in water can be preferably used. Specific examples of the water-soluble dye include basic dyes such as rhodamine B, rhodamine 6GCP (all manufactured by Sumitomo Chemical Co., Ltd.), methyl violet FN, and Victoria Blue FN; quinoline yellow SS-5G, quinoline yellow GC ( As described above, acid dyes such as Acid Magenta O, Acid Magenta O, Methyl Violet FB, and Victoria Blue FB; and the like. These water-soluble dyes may be used alone or in combination of two or more.
[0025]
The form of the water-soluble dye referred to in the present invention is not particularly limited, and may be the dye itself or an aqueous solution previously dissolved in water. In the case of the former, the necessary amount may be added to the emulsion as it is so that the desired dye concentration is obtained.In the case of the latter, an aqueous solution having a predetermined concentration is prepared and appropriately adjusted to obtain the desired dye concentration. The required amount may be added to the emulsion.
The amount of the water-soluble dye used is not particularly limited, but specifically, for example, is preferably 0.1 to 10 parts by weight, based on 100 parts by weight of the amino resin precursor in the emulsion, More preferably, it is 0.2 to 7 parts by weight, and still more preferably 0.3 to 5 parts by weight. If the amount is less than 0.1 part by weight, the chromaticity of the amino resin colored crosslinked particles may vary. If the amount exceeds 10 parts by weight, the amount becomes excessive with respect to the emulsified amino resin precursor, and the amino resin When the crosslinked particles are separated from the suspension containing the colored crosslinked particles, a large amount of the water-soluble dye is discharged together with the wastewater after the separation, so that the economy is poor and the environment may be adversely affected to some extent.
[0026]
When using an aqueous solution in which a water-soluble dye is dissolved in water for coloring with a water-soluble dye, the dye concentration in the aqueous solution is not particularly limited, but specifically, for example, 0.1 to 5% by weight. Preferably, it is more preferably 1 to 3% by weight. If the dye concentration is less than 0.1% by weight, the amount of the aqueous solution to be added becomes large, so that the productivity of amino resin colored crosslinked particles may be reduced. On the other hand, when the dye concentration is more than 5% by weight, the stability of the emulsion is reduced, so that the obtained amino resin colored crosslinked particles may be enlarged or the particles may aggregate. The method for preparing the aqueous solution obtained by dissolving the dye in water and the method for adding and mixing the aqueous solution to the emulsion are not particularly limited.
[0027]
In the coloring step, when both the basic water-soluble dye and the acidic water-soluble dye are used as the water-soluble dye to be added, the acidic water-soluble dye is added after the basic water-soluble dye is added. Is preferred. When a basic water-soluble dye is used as the water-soluble dye, the added dye has good familiarity with the resin and can be taken into the resin quickly and can be sufficiently dyed easily. This is because, when used, the added dye does not easily adapt to the resin and is present in the emulsion as free. In other words, if the acidic water-soluble dye is added first, the basic water-soluble dye is added to the place where the acidic water-soluble dye is released as described above, and the free acidic water-soluble dye is added. In addition, a basic water-soluble dye may form an insoluble complex to generate a precipitate not involved in dyeing. Therefore, when two or more types of water-soluble dyes are used, and when coloring is performed using a basic water-soluble dye and an acidic water-soluble dye, the basic affinity with the amino resin is good. If the water-soluble dye is added first, no free dye remains at that point, so even if an acidic water-soluble dye is added to this state, the above-described insoluble complex precipitate is not generated, which is preferable. . In addition, when a basic water-soluble dye is added first, an acidic water-soluble dye is easily taken in.
[0028]
In the production method of the present invention, the temperature of the emulsion from the start of the coloring step to the start of the curing step described below, specifically, from the start of adding the water-soluble dye described above to the emulsion. The temperature of the emulsion until the catalyst (curing catalyst) described later is added is preferably 25 ° C. or lower, more preferably 20 ° C. or lower, and even more preferably 15 ° C. or lower. By setting the temperature of the emulsion at 25 ° C. or lower, the tendency of the emulsified amino resin precursor to aggregate when or after the addition of the water-soluble dye can be effectively suppressed.
In the curing step, a catalyst (specifically, a curing catalyst) is added to the emulsion after the coloring step, and a curing reaction of the emulsified amino resin precursor is performed (the amino resin precursor is cured in an emulsion state). Thereby, amino resin colored crosslinked particles (specifically, a suspension of amino resin colored crosslinked particles) are obtained.
[0029]
As the catalyst (curing catalyst), an acid catalyst is suitable. Examples of the acid catalyst include mineral acids such as hydrochloric acid, sulfuric acid and phosphoric acid; ammonium salts of these mineral acids; sulfamic acid; sulfonic acids such as benzenesulfonic acid, paratoluenesulfonic acid and dodecylbenzenesulfonic acid; phthalic acid, benzoic acid, Organic acids such as acetic acid, propionic acid and salicylic acid can be used. Among the acid catalysts exemplified above, a mineral acid is preferable in terms of curing rate, and further, sulfuric acid is more preferable in terms of corrosiveness to an apparatus, safety in using a mineral acid, and the like. Further, when sulfuric acid is used as the above catalyst, for example, compared with the case where dodecylbenzene sulfonic acid is used, the amino resin colored crosslinked particles finally obtained do not discolor or have high solvent resistance. These may be used alone or in combination of two or more. The amount of the catalyst to be used is preferably 0.1 to 5 parts by weight, more preferably 0.3 to 5 parts by weight, based on 100 parts by weight of the amino resin precursor in the emulsion obtained by the emulsification step. It is 4.5 parts by weight, more preferably 0.5 to 4.0 parts by weight. If the amount of the catalyst exceeds 5 parts by weight, the emulsion state is destroyed, and the particles may aggregate. If the amount is less than 0.1 part by weight, the reaction requires a long time or hardens. May be insufficient. Similarly, the amount of the catalyst used is preferably 0.002 mol or more, more preferably 0.005 mol or more, and still more preferably 0 mol or more, per 1 mol of the amino compound used as the starting compound. 0.01 to 0.1 mol. If the amount of the catalyst is less than 0.002 mol per 1 mol of the amino compound, the reaction may take a long time or the curing may be insufficient.
[0030]
The curing reaction in the curing step is preferably performed at 15 (normal temperature) to 80 ° C., more preferably 20 to 70 ° C., and still more preferably 30 to 60 ° C., for at least 1 hour, and then at normal pressure or under pressure. It is preferable to carry out at a temperature in the range of from 150 to 150 ° C, more preferably from 60 to 130 ° C, and still more preferably from 60 to 100 ° C. If the reaction temperature of the curing reaction is less than 60 ° C, the curing does not proceed sufficiently, and the solvent resistance and heat resistance of the obtained amino resin colored crosslinked particles may be reduced. Requires a strong pressurized reactor, which is not economical.
The end point of the curing reaction may be determined by sampling or visual observation. Further, the reaction time of the curing reaction is not particularly limited.
[0031]
As the stirring method in the curing step, it is preferable to perform the stirring under the stirring with a generally known stirring device or the like.
In the curing step, the average particle diameter of the crosslinked amino resin particles obtained by curing the amino resin precursor in an emulsion state is preferably 0.1 to 30 μm, more preferably 0.5 to 25 μm, More preferably, it is 0.5 to 20 μm. In the present invention, in order to more reliably prevent the amino resin colored crosslinked particles finally obtained from firmly aggregating, a suspension after adding a catalyst (specifically, a curing catalyst) in the curing step. Inorganic particles (specifically, inorganic compound particles) are added to the mixture. By adding the inorganic particles used for such a purpose at a specific timing after the addition of the catalyst, as described above, it was remarkable when the inorganic particles were added after the addition of the water-soluble dye and before the addition of the catalyst. The problem of aggregation of the emulsified (emulsified) amino resin precursor can be easily solved.
[0032]
Regarding the timing of adding the inorganic particles, more specifically, after adding a catalyst (specifically, a curing catalyst), it is necessary to fix the inorganic particles to the surface of the amino resin colored crosslinked particles as the curing reaction proceeds. Yes, it is preferable to add the inorganic particles within 30 minutes after adding the catalyst, more preferably within 25 minutes, even more preferably within 20 minutes. If added within 30 minutes after the addition of the catalyst, the problem of aggregation of the emulsified amino resin precursor as described above is easily solved, and finally, the amino resin colored and crosslinked in which the inorganic particles are firmly fixed to the surface sufficiently. Particles can be obtained. If the catalyst is added for more than 30 minutes after the addition of the catalyst, the curing of the amino resin colored crosslinked particles may proceed excessively, and the inorganic particles may not be sufficiently fixed.
[0033]
As the inorganic particles, specifically, for example, silica fine particles, zirconia fine particles, alumina, alumina sol, serie sol, and the like are preferable, and among them, silica fine particles are more preferable because they are easily available. The specific surface area of the inorganic particles is 10 to 400 m ² / G, more preferably 20 to 350 m ² / G, more preferably 30 to 300 m ² / G. The particle diameter of the inorganic particles is more preferably 0.2 μm or less, more preferably 0.1 μm or less, and still more preferably 0.05 μm or less. When the specific surface area and the particle diameter are within the above ranges, a further excellent effect can be exhibited in preventing the finally obtained amino resin colored crosslinked particles from being firmly aggregated.
[0034]
The method of adding the inorganic particles to the suspension after the addition of the catalyst is not particularly limited, and specifically, for example, a method of adding the inorganic particles as they are (in the form of particles) or a method of adding the inorganic particles to water And a method of adding in a state of a dispersion liquid dispersed in the same. The amount of the inorganic particles added to the suspension is preferably from 1 to 30 parts by weight, more preferably from 2 to 28 parts by weight, based on 100 parts by weight of the amino resin colored crosslinked particles contained in the suspension. Preferably it is 3 to 25 parts by weight. When the amount is less than 1 part by weight, it may not be possible to sufficiently prevent the finally obtained amino resin colored crosslinked particles from aggregating firmly. May occur. In addition, as a stirring method when adding the inorganic particles, the method using the above-described device (a device having a high shearing force) capable of strong stirring stably fixes the inorganic particles to the amino resin colored crosslinked particles. It is preferred in that respect. At this time, by applying a certain high shear force or more, it is also possible to obtain amino resin colored crosslinked composite particles in which the inorganic particles are firmly fixed on the surface of the amino resin crosslinked particles.
[0035]
Further, the production method of the present invention, as described above, includes a coloring step of adding a water-soluble dye to the emulsion to obtain colored amino resin particles, and further obtained in the resinification step. A pre-coloring step of coloring the resin itself at the stage of the resinification step by adding a dispersion obtained by dispersing the dye in water to the reaction liquid may also be included. The dye used in the former coloring step is preferably a dye that disperses in water, that is, an oil-soluble dye. Specific examples of oil-soluble dyes include solvents such as Oil Orange B, Oil Blue BA (all manufactured by Chuo Gosei Kagaku Co., Ltd.), Azosol Brilliant Yellow 4GF, Azosol Fast Blue GLA, Oil Red TR-71 and the like. Soluble dyes; disperse dyes such as Fast Yellow YL, Fast Blue FG, Seriton Pink FF3B and Seriton Pink 3B; These dyes may be used alone or in combination of two or more.
[0036]
In addition, a pre-stage coloring step of adding a dispersion obtained by dispersing an oil-soluble dye in water to the reaction solution obtained in the resinification step, and a coloring step of adding a water-soluble dye to the emulsion after the emulsification step. When used in combination, amino resin colored crosslinked particles which are more sufficiently and uniformly colored, that is, the color tone of each particle is more uniform, can be obtained.
The content of the oil-soluble dye in the dispersion obtained by dispersing the oil-soluble dye in water is not particularly limited, but is preferably in the range of 1 to 50% by weight, and more preferably 20 to 40% by weight. It is more preferable that it is within Norioka. When the content of the oil-soluble dye is less than 1% by weight, the amount of the added dispersion becomes large, so that the productivity of amino resin colored crosslinked particles may decrease. On the other hand, when the content of the oil-soluble dye is more than 50% by weight, the fluidity of the dispersion is reduced, so that the handleability at the time of addition is reduced and the addition may be troublesome. Further, since the oil-soluble dye has poor wettability with water, a dispersing aid can be used as necessary when dispersing the dye in water. The method for preparing a dispersion obtained by dispersing the dye in water, and the method for adding and mixing the dispersion to the reaction solution are not particularly limited.
[0037]
After the addition of the dispersion obtained by dispersing the oil-soluble dye in water, the pH of the reaction solution (solution) is adjusted using an alkali agent such as sodium carbonate, sodium hydroxide, potassium hydroxide, or aqueous ammonia. It is preferable to adjust within the range of 6 to 12, more preferably within the range of 7 to 9. Thereby, the condensation and curing of the amino resin precursor in the curing step can be sufficiently controlled. The amount of the alkaline agent used is not particularly limited. Further, a method in which the alkali agent is added to and mixed with the reaction solution in the form of an aqueous solution is suitable, but the method is not particularly limited.
The production method of the present invention may include a neutralization step for neutralizing the suspension containing the amino resin colored crosslinked particles obtained in the curing step. The neutralization step is preferably performed when an acid catalyst such as sulfuric acid is used as the curing catalyst in the curing step. By performing the neutralization step, the acid catalyst can be removed (specifically, the acid catalyst can be neutralized). For example, when the amino resin colored crosslinked particles are heated in a heating step described below, Discoloration (for example, yellowing) of the resin-colored crosslinked particles can be suppressed. The above-described neutralization step is a preferred embodiment for obtaining bright colored particles having excellent heat resistance.
[0038]
The term “neutralization” in the neutralization step means that the pH of the suspension containing the amino resin colored crosslinked particles is preferably 5 or more, more preferably 5 to 9. When the pH of the suspension is less than 5, the amino resin colored crosslinked particles may be discolored in a heating step or the like described below because the acid catalyst remains. By adjusting the pH of the suspension to the above range by the neutralization, amino resin colored crosslinked particles having high hardness, excellent solvent resistance and heat resistance, and without discoloration can be obtained.
As the neutralizing agent that can be used in the neutralization step, for example, an alkaline substance is suitable. Examples of the alkaline substance include sodium carbonate, sodium hydroxide, potassium hydroxide, and ammonia. Among them, sodium hydroxide is preferable, and an aqueous sodium hydroxide solution is suitably used, since handling is easy. . These may be used alone or in combination of two or more.
[0039]
The production method of the present invention can include a separation step of taking out the amino resin colored crosslinked particles from the suspension of amino resin colored crosslinked particles obtained after the curing step or the neutralization step.
Examples of the method of removing the amino resin colored crosslinked particles from the suspension (separation method) include a method of separating by filtration and a method of using a separator such as a centrifuge, but are not particularly limited. Ordinarily known separation methods can be used. The amino resin colored crosslinked particles after being removed from the suspension may be washed with water or the like, if necessary.
[0040]
In the production method of the present invention, it is preferable to perform a heating step of heating the amino resin colored crosslinked particles taken out through the separation step at a temperature of 130 to 190 ° C. By performing the heating step, moisture and remaining formaldehyde adhering to the amino resin colored crosslinked particles can be removed, and condensation (crosslinking) in the amino resin colored crosslinked particles can be further promoted. it can. When the heating temperature is lower than 130 ° C., condensation (crosslinking) in the amino resin colored crosslinked particles cannot be sufficiently promoted, and the hardness, solvent resistance and heat resistance of the amino resin colored crosslinked particles are improved. When the temperature exceeds 190 ° C., the obtained amino resin colored crosslinked particles may be discolored. Even when the above-described neutralization step is performed, the effect when the heating temperature is outside the above temperature range is the same. After performing the neutralization step, by setting the heating temperature of the amino resin colored crosslinked particles within the above range, the hardness is high, excellent in solvent resistance and heat resistance, and the amino resin colored crosslinked particles without discoloration. Obtainable.
[0041]
The heating method in the heating step is not particularly limited, and a generally known heating method may be used.
The heating step may be completed, for example, when the moisture content of the amino resin colored crosslinked particles becomes 3% by weight or less. The heating time is not particularly limited.
In the production method of the present invention, for example, particles having an average particle diameter of 10 μm or less can be obtained by performing steps such as pulverization (crushing) and classification as necessary after the heating step.
ADVANTAGE OF THE INVENTION According to the manufacturing method concerning this invention, the amino resin coloring crosslinked particle useful for a light diffusing agent, an abrasive, etc. with a comparatively small particle diameter can be manufactured stably at low cost.
[0042]
The average particle size of the amino resin colored crosslinked particles obtained by the production method of the present invention is not particularly limited, but specifically, is preferably from 0.05 to 30 μm, more preferably from 0.1 to 15 μm It is. When the average particle diameter is less than 0.05 μm, the matting effect when used as a matting agent for paint may not be sufficient, and when it exceeds 30 μm, the polishing accuracy when used as an abrasive may be insufficient. It may be worse.
The standard deviation of the average particle size of the amino resin colored crosslinked particles obtained by the production method of the present invention is preferably 6 μm or less, more preferably 4 μm or less, and still more preferably 2 μm or less. When the standard deviation of the average particle size exceeds 6 μm, the particle size distribution is widened, and when used as a coloring agent, there is a possibility that vividness may be lacking.
[0043]
The average particle size and the standard deviation of the obtained amino resin colored crosslinked particles and the standard deviation thereof fall within the above ranges, for example, the emulsification step and the curing step, and further, the processing conditions and reaction conditions may be appropriately set in the heating step and the like. .
The degree of crosslinking, the average molecular weight, the molecular weight distribution, and the like of the amino resin constituting the finally obtained amino resin colored crosslinked particles are not particularly limited.
For the amino resin constituting the amino resin colored crosslinked particles obtained by the production method of the present invention, the molar ratio of the structural unit derived from the amino compound to the structural unit derived from formaldehyde is 1 mol of the structural unit derived from the amino compound. The number of moles of the structural unit derived from formaldehyde is preferably 1.05 to 3 moles, more preferably 1.1 to 2.5 moles. When the number of moles of the structural unit derived from formaldehyde is less than 1.05 mole per mole of the structural unit derived from the amino compound, the degree of crosslinking of the obtained amino resin colored crosslinked particles becomes low, and the heat resistance and the solvent resistance If it exceeds 3 moles, the cured amino resin colored crosslinked particles may not be sufficiently cured, and the heat resistance and the solvent resistance may be reduced.
[0044]
Since the amino resin colored crosslinked particles obtained by the production method of the present invention have the performance and physical properties as described above, for example, as in the past, in addition to use as a coloring agent, matting agents, light diffusion Agents, abrasives, coating agents for various films; fillers such as polyolefins and polyvinyl chlorides, various rubbers, various paints, and toners; rheology control agents, digital paper, and cosmetics.
Further, in the present invention, the suspension containing the amino resin colored crosslinked particles can be used after being extracted from the reaction system and optionally purified. Therefore, the suspension containing the amino resin colored crosslinked particles produced through the production method of the present invention is also one of the embodiments. Further, an abrasive or the like formed from a suspension containing amino-resin-colored crosslinked particles, which is manufactured through the manufacturing method of the present invention, is one of the embodiments.
[0045]
【Example】
Hereinafter, the present invention will be described more specifically 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. “Liter” may be simply described as “L”.
[Example 1]
3200 g (17.1 mol) of benzoguanamine as an amino compound was placed in a reaction vessel having a capacity of 10 L equipped with a stirrer, a reflux condenser, a thermometer and a vibrating viscometer (product name: MIVI 6001 manufactured by MIVI ITS Japan). ), 2810 g of formalin having a concentration of 37% by weight (34.7 mol of formaldehyde), and 10 g of an aqueous solution of 10% by weight of sodium carbonate (0.01 mol of sodium carbonate), and the mixture was heated at 96 ° C. while stirring and heated. Was.
[0046]
And the viscosity of the reaction solution is 4.5 × 10 ^-2 When Pa · s was reached, the reaction solution was cooled to complete the resinification step. As a result, a reaction solution containing an amino resin precursor which was an initial condensate of benzoguanamine and formaldehyde was obtained.
Next, polyvinyl alcohol as an emulsifier (Kuraray Co., Ltd., product name: 20 mL) was placed in a 20 L reactor equipped with a reflux condenser, a homomixer (a stirrer manufactured by Tokushu Kika Kogyo Co., Ltd.) and a thermometer. An aqueous solution obtained by dissolving 100 g of PVA205) in 5150 g of water was charged and heated to 75 ° C. while stirring. Then, after adding the reaction solution obtained in the resinification step to the reaction vessel, the temperature of the solution was raised to 75 ° C., and while maintaining the temperature at 75 ° C., the contents were vigorously stirred at a rotation speed of 7000 rpm, By emulsifying the resin precursor, an emulsion having an amino resin precursor concentration of 38.3% by weight was obtained, and the emulsification step was completed. When the amino resin precursor in an emulsion state in the obtained emulsion was measured with a Coulter Multisizer II (manufactured by Coulter, number of measured particles: 30,000), the average particle size (d50) was 3.8 μm, The standard deviation of the particle diameter was 1.8 μm. Then, the obtained emulsion was cooled to 30 ° C.
[0047]
Next, an aqueous solution obtained by dissolving 7 g of “rhodamine B” as a basic water-soluble dye in 350 g of pure water was added to the above emulsion, and the mixture was stirred for 5 minutes. Subsequently, an aqueous solution obtained by dissolving 7 g of “Acid Red 52” as an acidic aqueous dye in 350 g of pure water was added to the above emulsion and stirred for 5 minutes. The temperature of the emulsion did not fall below 25 ° C. from the start of the addition of the water-soluble dye to the addition of the catalyst described below.
Thereafter, an aqueous solution obtained by dissolving 40 g of sulfuric acid as a catalyst in 1200 g of pure water was added to the above emulsion and stirred for 10 minutes. After the stirring, a liquid obtained by uniformly dispersing 320 g of ultrafine silica (product name: Aerosil 200, manufactured by Nippon Aerosil Co., Ltd.) in 1400 g of water is added to the above emulsion, and the mixture is stirred until the temperature becomes 90 ° C. The temperature was raised at 10 ° C./hr. After the temperature reached 90 ° C., the emulsion was maintained at this temperature for 1 hour to condense and cure the emulsified amino resin precursor to obtain amino resin colored crosslinked particles, and the curing step was completed. Thus, the total reaction time is 7 hours.
[0048]
After cooling the suspension of the amino resin colored crosslinked particles obtained in the curing step to 30 ° C., the pH of the suspension is adjusted to 7.5 using a 5% by weight aqueous sodium hydroxide solution, and the neutralization step is performed. Finished.
After the neutralization step, amino resin colored crosslinked particles were removed from the suspension by filtration. The removed amino resin colored crosslinked particles are heat-treated at 150 ° C. for 3 hours, then placed in a mortar, and crushed evenly by applying light force with a pestle, so that the amino resin colored crosslinked pink powder can be obtained. Particles were obtained.
When the obtained amino resin colored crosslinked particles in the form of a pink powder were measured with a Coulter Multisizer II (manufactured by Coulter, number of measured particles: 30,000), the average particle size (d50) was 3.9 μm, and the particle size was 3.9 μm. Was 2.0 μm.
[0049]
[Example 2]
Heat treatment was carried out in the same manner as in Example 1 except that sulfuric acid as a catalyst was added to the emulsion, and the mixture was stirred for 25 minutes to introduce ultrafine silica particles. The powder after the heat treatment was placed in a mortar and lightly applied with a pestle, whereby the powder was uniformly crushed, and amino resin colored crosslinked particles in the form of pink powder were obtained.
When the obtained amino resin colored crosslinked particles in the form of pink powder were measured with a Coulter Multisizer II (manufactured by Coulter, number of measured particles: 30000), the average particle size (d50) was 4.0 μm, and the particle size was 4.0 μm. Had a standard deviation of 2.1 μm.
[0050]
[Example 3]
Heat treatment was carried out in the same manner as in Example 1 except that sulfuric acid as a catalyst was added to the emulsion, and the mixture was stirred for 35 minutes to introduce ultrafine silica particles. When the powder after the heat treatment was put into a mortar and crushed by applying a light force with a pestle, the powder was hard and agglomerated and could be crushed uniformly to some extent. Crushing could not be carried out sufficiently uniformly compared to the obtained powder. Thus, amino resin colored crosslinked particles in the form of a pink powder whose crushing was not sufficiently uniform were obtained.
When the obtained amino resin colored crosslinked particles in the form of pink powder were measured with a Coulter Multisizer II (manufactured by Coulter, number of measured particles: 30,000), the average particle diameter (d50) was 6.2 μm, and the particle diameter was 6.2 μm. Had a standard deviation of 4.1 μm.
[0051]
[Example 4]
The obtained emulsion was cooled to 25 ° C., and the temperature of the emulsion was maintained at 25 ° C. or lower from the start of adding the water-soluble dye to the time when the catalyst described below was added. By carrying out the operation, pink powdery amino resin colored crosslinked particles were obtained.
When the obtained amino resin colored crosslinked particles in the form of a pink powder were measured with a Coulter Multisizer II (manufactured by Coulter, number of measured particles: 30,000), the average particle diameter (d50) was 3.8 μm, and the particle diameter was 3.8 μm. Had a standard deviation of 1.5 μm.
[0052]
[Example 5]
By carrying out the same reaction step and emulsion step as in Example 1, an emulsion of the amino resin precursor was obtained. Next, in Example 1, the order of addition of the basic water-soluble dye and the acidic water-soluble dye was reversed so that Acid Red 52 as the acidic water-soluble dye was given first, and rhodamine was used as the basic water-soluble dye. Later addition of B precipitated insoluble material, presumably dye aggregates. After removing the precipitate, amino resin-colored crosslinked particles in the form of a pink powder were obtained in the same manner as in Example 1, but the coloration degree was lower than that of the amino resin-colored crosslinked particles obtained in Example 1 ( Color).
[0053]
When the obtained amino resin colored crosslinked particles in the form of pink powder were measured with a Coulter Multisizer II (manufactured by Coulter, number of measured particles: 30000), the average particle size (d50) was 4.0 μm, and the particle size was 4.0 μm. Was 2.0 μm.
[Comparative Example 1]
After obtaining a colored amino resin precursor emulsion by performing the same reaction step, emulsion step and coloring step as in Example 1, the same as in Example 1 before adding sulfuric acid as a catalyst. When ultrafine silica particles were added to the above emulsion and stirred, the particles were aggregated, the emulsion was thickened, and the stirring became impossible.
[0054]
【The invention's effect】
According to the present invention, when obtaining a crosslinked amino resin particles by adding a water-soluble dye to the emulsion before performing the curing reaction, sufficiently excellent crushability by adding inorganic particles. It is possible to provide a method for producing amino resin colored crosslinked particles that can be exerted.

Claims (4)

Coloring the amino resin precursor by adding a water-soluble dye to an emulsion obtained by emulsifying an amino resin precursor obtained by reacting an amino compound with formaldehyde, and then adding a catalyst to the emulsion; In a method of producing amino resin colored crosslinked particles by curing,
A method for producing amino resin colored crosslinked particles, wherein inorganic particles are added to the emulsion after the addition of the catalyst. The method for producing amino resin colored crosslinked particles according to claim 1, wherein the inorganic particles are added within 30 minutes after the catalyst is added. 3. The aqueous dye solution according to claim 1, wherein a basic water-soluble dye and an acidic water-soluble dye are added as the dye aqueous solution, and the acidic dye aqueous solution is added after the basic dye aqueous solution is added. A method for producing amino resin colored crosslinked particles. The method for producing amino resin-colored crosslinked particles according to any one of claims 1 to 3, wherein the temperature of the emulsion from the start of the addition of the water-soluble dye to the addition of the catalyst is 25 ° C or lower.