JPS5936665B2 - Funmatsujiyouganriyoubunsantaisosabutsunoseizohouhou - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION 10 The present invention relates to a method for producing a powdered pigment dispersion composition.

Powdered pigment dispersion compositions have wide applications in processed pigments, colored plastic pellets, powder coatings, slurry coatings, and the like.

In particular, powder coatings and 15 slurry coatings do not contain organic solvents, the former can be recovered and reused, and the latter has the advantage of not causing any danger of explosion or fire, so their usage has increased significantly in recent years. It shows the trend of As a method for producing a powdered pigment dispersion composition, 20. Usually, a pigment is added to a solid resin.
A common method is to heat-melt and mix a curing agent and other additives, and then mechanically crush the mixture.

However, with such methods, it is difficult to control the particle size and particle size distribution of powder particles. In addition, since hot melt mixing is performed, thermosetting resins that react and harden at low temperatures according to 25(1) become gelled and cannot be used.

(2) Color matching is difficult and takes a long time.

(3) Since pigments, curing agents, etc. cannot be sufficiently dispersed in the resin, coating films, molded products, etc. formed using the obtained powdered pigment dispersion composition 30 have poor smoothness and sharpness. The finished surface is dull and the aesthetic effect is extremely low. (4) Equipment such as extruders and kneaders used for hot melt mixing are expensive.

There was a defect of 35 mag.

As a method to improve these drawbacks of the prior art, after dispersing the pigment in a solvent solution of a natural or synthetic resin, the resin is dispersed in a large amount of solvent that does not dissolve but is compatible with the solvent in the solution. A method in which this dispersion is injected under stirring (Japanese Patent Publication No. 44-6399), a method in which a coagulating liquid is mixed with a liquid paint in a proportion inversely proportional to the required particle size of the powder paint (
JP-A No. 48-52851), a method of spraying a synthetic resin solvent solution and bringing it into contact with an isolating agent at the time (Japanese Patent Publication No. 1983-52851),
A method of obtaining particles by wet pulverization in a broad sense has been proposed, such as Japanese Patent Publication No. 42,615.

In these methods, an extremely large amount of the dispersion medium (usually water is used) used to suspend or form solid particles of the resin solution is required, and the dispersion medium used after separating the formed solid resin particles is a solvent or isolating agent. If they are disposed of as they are, they become a source of environmental pollution, and it is extremely difficult to remove or separate and recover the solvents and sequestering agents, and the processing costs are high.

An object of the present invention is to provide a method for producing a powdery pigment dispersion composition that eliminates the drawbacks of existing techniques as described above.

Such purpose is achieved according to the present invention by: (1) solid resin;
Solubility in water is 10% (weight) or more, and 1
finely dispersing the powdered pigment and/or the water-containing pigment cake in a resin solution in the water-in-oil (W/O) emulsion region consisting of a water-soluble organic solvent with a boiling point below 00°C and water; (4) A step of spraying the pigment-dispersed resin solution into stirring water of up to 10 times the weight of the pigment-dispersed resin solution, and guiding the pigment-dispersed resin solution to a coagulation and precipitation region to generate and precipitate resin particles, (1:l ) The step of separating the resin particle aggregates generated in the step αIi) above from the water-solvent mixture, washing, and drying, and the step of (111● mechanically crushing the dried resin particle aggregates) This is achieved by performing a combination of steps.

As a first step, the present invention aims to create a resin solution that exhibits a stable W/O emulsion under stirring in a product system consisting of a solid resin, a water-soluble solvent as a solvent for the solid resin, and water as a non-solvent. Disperse the pigment.

Since triangular coordinates are convenient for showing the relationship between the composition and state of the system consisting of the three components mentioned above, the following explanation will be made using triangular coordinates. FIG. 1 shows a triangular coordinate system consisting of three components: acrylic resin, methyl ethyl ketone, and water.

In a system whose composition point is on a straight line passing through the vertex corresponding to the non-solvent (water) in the figure, the ratio of solid resin (acrylic resin) to solvent (methyl ethyl ketone) is constant. For example 3
The situation when water is dropped into a 0% acrylic resin methyl ethyl ketone solution is, in this triangular coordinate system, the point 70 on the line connecting the vertices corresponding to the acrylic resin and ethyl methyl ketone and the vertex corresponding to water. On the connected line (the weight ratio of acrylic resin and methyl ethyl ketone is 3/7).
) from the bottom to the top,
The state of each composition can be found by looking at the state display in triangular coordinates. In other words, in a range with a small amount of water, it exhibits a W/O type emulsion that is stable under stirring, but when water is added beyond a certain range, a phase transformation phenomenon occurs, resulting in a state where droplets of spherical resin solution are dispersed in water. (0/W type emulsion). If water is further added, the 0/W emulsion dispersion state cannot be maintained even under stirring conditions, and the resin particles coagulate and precipitate or adhere to the container wall. In the phase change process explained above, in the first step, a water-containing pigment cake or powder pigment is added to the W/0 type emulsion resin solution (especially when using a water-containing pigment cake, the three-component composition is The formulation is determined so that the final product still exhibits a W/O type emulsion state.

), adjust the viscosity to an appropriate level, and knead and disperse using a pigment dispersion device such as a ball mill or attritor to obtain a dispersion in which the pigment is finely dispersed. Next, in the second step, the dispersion is diluted to a viscosity suitable for spraying, if necessary, and sprayed into water under stirring using a two-fluid nozzle, a pressure nozzle, or the like.

In this step, resin particles are formed and precipitated by introducing the three-component ratio of solid resin, water, and solvent into the coagulation and precipitation region shown in FIG. One of the main objects of the present invention is to provide a formulation that minimizes the amount of water as a non-solvent when resin particles are formed and precipitated. For this purpose, the amount of water used is 10 times the amount (weight) of the resin solution to be sprayed or less. In the second step, the particle size and particle size distribution of the resin particles should be controlled by adjusting the type of solvent, the viscosity of the resin solution in which the pigment is dispersed, the spray pressure, and the stirring conditions of the water. Realize. In the third step, the resin particle agglomerated precipitate produced as described above and the liquid phase are separated. For this purpose, for example, a pressure filter, a vacuum filter, a centrifuge, etc. can be used. At this stage as much of the water/solvent mixture as possible must be removed from the resin particle flocculation precipitate. If a relatively large amount of solvent remains in the coagulated precipitate, the coagulated precipitate becomes sticky and, when dried, forms a lump that requires a large amount of energy to mechanically crush. In order to prevent this phenomenon, an operation is performed in which the resin particle aggregate is separated and then washed with the same amount of water. It is effective to wash 2 to 4 times. In the fourth step, the washed resin particle aggregate is dehydrated, dried, mechanically pulverized, and classified if necessary to obtain a powdered pigment dispersion composition having a desired particle size range. As mentioned above, in the present invention, the coagulated precipitate is separated and washed to remove the solvent remaining in the precipitate and reduce the stickiness.
When this is dried, the particles are crushed from the agglomerated portions with a slight force, and can be easily crushed into primary particles. The solid resin used in the present invention is a water-insoluble resin commonly used in the production of paints.

This includes, for example, phenolic resin, amino resin, epoxy resin, acrylic resin, polyester resin, polyurethane,
Vinyl chloride resin, etc. The water-soluble organic solvent has a solubility in water (expressed as a percentage of the weight of the water-soluble solvent to the weight of water at 20°C) of 10% or more and a boiling point of 100°C or less.

A solvent with a solubility lower than 10% will require a large amount of water to extract the solvent from the resin solution and wash the agglomerated precipitate of resin particles, making it unsuitable for the purpose of the present invention. Solubility is 20%
The above compounds are particularly preferable because the solvent can be extracted and washed with a small amount of water. If the boiling point is higher than 100°C, the proportion of water in the azeotropic mixture of solvent and water obtained by distilling the remaining solvent aqueous solution after separating the coagulated precipitate increases, and the recycled solvent produces a large amount of solid resin. It cannot be dissolved and is of little practical use. Specific examples of suitable solvents include ketones such as methyl ethyl ketone and acetone, ethers such as tetrahydrofuran, esters such as methyl acetate, methyl formate, and ethyl formate, and methanol, ethanol, 1-propanol, 2-propanol, and 2-butanol. , t-butanol and other alcohols. The pigment may be any inorganic or organic pigment that is commonly used in the production of paints, as long as it does not interfere with the formation of an emulsion or the aggregation and precipitation of resin particles.

It is also possible to produce a pigment in water in the pigment manufacturing process and use the resulting precipitate or a water-containing pigment cake obtained by filtering it through P. The pigment in such a water-containing pigment cake is in the state of primary particles and is extremely easily dispersed in a w/o emulsion resin solution consisting of a solid resin, a water-soluble solvent, and water, and is therefore particularly suitable for the present invention. It is. This is W
/ Since water exists in the type 0 emulsion resin solution, when the water-containing pigment cake is added, the water in the water-containing pigment cake does not rapidly transfer to the resin solution, and pigment aggregates due to so-called pigment shock occur. This is thought to be due to the fact that it is not generated. The resin particle aggregate may be pulverized using an apparatus normally used for pulverizing solid resins.

These include, for example, dowel crushers, fine reduction type joint crushers, cone crushers, hydro cone crushers, double roll crushers, edge runners, gear integrators, hammer mills, impeller breakers, disk crushers, screw crushers, and toothed crushers. There are disc crushers, rotary crushers, etc. According to the method of the present invention, the following advantages are obtained.

(1) Since the amount of water used to extract the solvent from the resin solution is small, the remaining solvent aqueous solution after separating the agglomerated precipitates of resin particles from P has a relatively high concentration, and by distilling it, the solvent is recovered primarily as an azeotrope with water,
It can be reused and recycled for melting solid resins. 5(2) Since a water-containing pigment cake can be used, it is possible to easily prepare a pigment dispersion in which even primary particles are dispersed.

(3) Since organic solvents are used in combination with water, there is little impact on the human body during the manufacturing process, and the risk of fire is also low.

(4) The particle size and particle size distribution of the resin particles can be controlled by changing the viscosity, spraying conditions, and stirring conditions of the resin solution.

The present invention will be explained below with reference to Examples.

In addition, [part] and "%" in the examples mean "weight" and "weight %", respectively. Example 1 Azeotropic fraction (MEK) of methyl ethyl ketone (MEK) and water
solid acrylic resin (product name SAD-1)
, produced by Sumitomo Chemical Industries) to create a 30% resin solution in the W/0 type emulsion region, and 1,700 parts of this solution was added to a hydrated iron oxide pigment cake (trade name: Bengara Tenyo #502, manufactured by Rikyun Sangyo). 150 parts of sebacic acid as a curing agent and 30 parts of a nonionic surfactant were added to the mixture, and the mixture was heated at a rotation speed of 150 rpm using a small attritor with an internal volume of 5'. p
．． The mixture was kneaded at m for 60 minutes to obtain a millbase with a pigment dispersion degree (determined using a grind gauge, hereinafter the same) of 5 μm or less.

Add 280 parts of the above 30% resin solution to 2000 parts of this mill base.
0 parts was added to adjust the viscosity, and the mixture was heated at 800 rpm. p. 32,000 stirred by a turbine-type stirrer rotating at m
of water through a 3.0-diameter pressure nozzle.

After spraying, the mixture was stirred for 5 minutes, and the resulting resin particle aggregates were separated using a small centrifuge to obtain 3000 parts of resin particle aggregates. Approximately the same volume of water was added to the obtained aggregate, and the operation of thoroughly washing and centrifuging was performed twice. Next, the resin particle aggregate was dried in a vacuum dryer for 24 hours, then milled into a fine powder using a hammer mill, and classified to obtain 1,400 parts of a powdered coating material (Paint No. 1) that passed through a 120-mesh sieve. In addition,
100,000 parts of water was required to extract the MEK until the resin particles became non-stick in water as in the conventional wet milling method. Example 2 Azeotropic distillate of tetrohydrophane and water (THF: 95.
7%) and solid polyester resin (saturated polyethylene terephthalate resin) to make a 44.1% solution in the W/O type emulsion region, 223 parts of phthalocyanine blue was added to 1190 parts of this solution, and a small 51. Rotation speed 150r with attritor. p. The mixture was kneaded at m for 180 minutes to obtain a mill base having a pigment dispersion degree of 5 microns or less.

Add 210 parts of an azeotropic distillate of tetrahydrofuran and water to 1,000 parts of this mill base, stir and mix uniformly, and add this to 8,500 parts of water that is being stirred with a turbine-type stirrer using a two-fluid nozzle type sprayer. Sprayed.

The resulting aggregates of resin particles are centrifuged to reduce the solid content to 40%.
An aggregate of resin particles was obtained. Approximately the same volume of water was added to this, and the operation of thoroughly washing and centrifuging was repeated three times.The resin particle aggregates were dried in a vacuum dryer for 12 hours, and then coarsely crushed using a high-speed mixer. A processed pigment was obtained. It was confirmed by microscopic observation that this was a porous aggregate in which several resin particles were aggregated. As in Example 1, the amount of water required in the conventional wet pulverization method was measured and found to be 36,000 parts in this system. Example 3 A 30% resin solution in the W/O type emulsion region was prepared by dissolving an epoxy resin (trade name "Epicote #1004", manufactured by Ciel Chemical Co., Ltd.) in acetone containing 2% water.
．． To 8 parts, 14.7 parts of a diazo yellow pigment and 0.3 parts of a nonionic surfactant were added and kneaded in a pebble mill for 2 days to obtain a millbase with a pigment dispersity of 5 microns or less.

50 parts of acetone was added to 100 parts of this mill base to adjust the viscosity, and the mixture was heated to 900 rpm. p. The mixture was sprayed through a 3.0' diameter pressure nozzle into 500 parts of water which was being stirred by a turbine type stirrer rotating at m.m.

After centrifuging the generated resin particle aggregates, repeating the washing and centrifugation process twice, and drying them in a vacuum dryer,
A processed pigment was obtained by coarsely crushing with a high-speed mixer. This processed pigment has a pigment content of 36 A) ('.In addition, as in Example 1, the amount of water required by the conventional wet grinding method was determined to be 26.
It was 00 copies. Comparative Example 1 56.7 parts of solid resin used in Example 1, 29 parts of iron oxide pigment
5.0 parts of sebacic acid and 1 part of nonionic surfactant
800 rpm using a 300' high speed mixer. p. After mixing at m for 3 minutes, the mixture was passed through a twin-screw extruder to melt and mix, thereby dispersing the pigment.

After cooling, the mixture was coarsely crushed using a high-speed mixer, then pulverized using a hammer mill, and classified to obtain a powdered coating material that passed through a 120-mesh sieve. The melt mixing using the extruder was carried out by circulating and passing the mixed composition five times, and the pigment dispersion degree after each pass was 45 microns after two passes, and 3 microns after two passes.
The particle size was 40 microns after passing twice, and 38 microns after passing four times and five times, and even finer dispersion could not be achieved even after passing four times or more. Comparative Example 2 70 parts of the solid resin used in Example 2, 30 parts of phthalocyanine pull, and 1.0 part of nonionic surfactant were mixed at a rotation speed of 1000 rpm using a small high-speed mixer. p. The mixture was mixed for 4 minutes using a pressurized kneader, and then melt-kneaded for 5 hours using a pressure kneader.

After cooling, it was pulverized in a tank to obtain a processed pigment. Comparative Example 3 After mixing 64.0 parts of the epoxy resin used in Example 3, 36.0 parts of the diazo yellow pigment, and 0.7 parts of the nonionic surfactant, they were melt-kneaded using a twin-screw extruder.

After cooling, this was crushed using a high-speed mixer to obtain a processed pigment. Comparative Test 1 The powder coatings prepared in Example 1 and Comparative Example 1 were electrostatically applied onto a polished steel plate, and baked and dried at 220° C. for 20 minutes to obtain a coating film with a thickness of 50 microns.

Table 1 shows the results of a coating film property test using Samples 1 and 2, respectively. Comparative Test 2 4 each of the processed pigments obtained in Example 2 and Comparative Example 2
After adding 5 parts of polyester resin and 5 parts of cyclohexanone to the same volume and stirring to completely dissolve them, the degree of pigment dispersion was determined, and it was found that the pigment dispersion using the processed pigment obtained from Example 2 was 5 microns or less, and the comparative example The one using the processed pigment obtained from No. 2 had a diameter of 55 microns.

Comparative Test 3 Using the processed pigments of Example 2 and Comparative Example 2, each mixture was mixed using a high-speed dispenser until the processed pigments were dissolved to prepare a solution-type paint.

The viscosity of these paints was adjusted to 25 seconds/FOrdcap #4 at 20°C, spray painted onto a polished mild steel plate, and heated at 230°C.
The coating was baked and dried for 15 minutes to obtain a coating film with a thickness of 40 microns. Samples 3 and 4 were used, respectively, and their coating film properties are shown in Table 1. Comparative Test 4 43 parts of solid polyester resin was added to 57 parts each of the processed pigments of Example 2 and Comparative Example 2, and after mixing with a high-speed mixer, the mixture was heated with a twin-screw extruder at a temperature of 160°C and a discharge rate of 1.
The mixture was melt-kneaded at a rate of 0 k9/hour, cooled, and coarsely crushed using a high-speed mixer, then made into a fine powder using a hammer mill, and classified to obtain a powdered coating material that passed through a 120-mesh sieve.

These powder coatings were electrostatically applied to a polished steel plate and baked and dried at 230°C for 10 minutes to form a coating film with a thickness of 60 microns.

These are designated as Samples 5 and 6, respectively, and their coating film properties are shown in Table 1. Comparative Test 5 20 parts each of the processed pigments of Example 3 and Comparative Example 3 were mixed with 4 parts of ultrafinely ground dicyandiamide, solid. 75 parts of epoxy resin was added and mixed using a high-speed mixer, and then melt-kneaded using a twin-screw extruder at a temperature of 100° C. and a discharge rate of 15 kg/hour.

After cooling, the mixture was coarsely crushed using a high-speed mixer, further finely crushed using a hammer mill, and then classified using a 120-mesh sieve to obtain a powder coating. These powder coatings are applied electrostatically to polished steel plates,
It was baked and dried at 200°C for 30 minutes to form a coating film with a thickness of 90 microns.

These were designated as Samples 7 and 8, respectively, and the results of the coating film property tests are shown in Table 1.

[Brief explanation of the drawing]

FIG. 1 shows the relationship between the composition and state of a ternary system consisting of solid acrylic resin, methyl ethyl ketone, and water.

Claims (1)

[Claims] 1 (i) Solid resin, resin in the water-in-oil (W/O) type emulsion region consisting of water and a water-soluble organic solvent with a solubility in water of 10% by weight or more and a boiling point of 100°C or less A step of finely dispersing a powdered pigment and/or a water-containing pigment cake in a solution; (ii) spraying the pigment-dispersed resin solution into stirring water of up to 10 times the weight of the pigment-dispersed resin solution; (iii) a step of guiding the resin particles to a coagulation-sedimentation region to generate and precipitate them; (iii) the above (i)
separating the aggregates of resin particles produced in step i) from the water-solvent mixture, washing and drying; and (iii)
i) mechanically crushing the dried resin particle aggregate;
A method for producing a powdery pigment dispersion composition, characterized in that it consists of a combination of.