JP2005179349A - Method for producing composite particles - Google Patents

Abstract

An object of the present invention is to provide a method for producing composite particles in which organic fine particles are firmly fixed on the surface of an inorganic powder by a simple production process without using an organic solvent harmful to the human body.
After mixing organic fine particles with an inorganic powder, the organic fine particles are plasticized in a container in the presence of carbon dioxide at a critical temperature or higher and a pressure of 4 MPa or higher to remove carbon dioxide. A method for producing composite particles fixed on a powder surface, and composite particles for cosmetics obtained by the production method.
[Selection figure] None

Description

  The present invention relates to a method for producing composite particles. More specifically, for paints, ink jet printer inks, toners, cosmetics, etc. with controlled water repellency, oil repellency, optical properties, UV protection, feel, safety, activity, color tone, dispersion stability, and weather resistance. The present invention relates to a method for producing composite particles that can be suitably used, and composite particles obtained by the production method.

  As a method for compounding fine particles on the powder surface, a dry blend method in which the particles are compounded by mechanical mixing (see, for example, Patent Document 1), particles are dispersed in an organic solvent, and a slurry is obtained by spray drying. A solvent volatilization method for evaporating (for example, see Patent Document 2) is known.

However, the dry blend method has a drawback that the adhesion of the organic fine particles to the inorganic powder is weak. In addition, in the solvent volatilization method and the poor solvent method, the organic solvent used may ignite, the organic solvent may remain in the obtained particles and may be harmful to the human body, or the smell may be deteriorated. It has drawbacks and requires a solvent removal operation by heating. Further, the use of a solvent causes a capillary condensation action, and the resulting particles agglomerate, so that there is a disadvantage that the operation is complicated, for example, a pulverization / classification step is required.
Japanese Patent Laid-Open No. 9-12430 Japanese Patent Laid-Open No. 9-48707

  An object of the present invention is to provide a method for producing composite particles in which organic fine particles are firmly fixed on the surface of an inorganic powder by a simple production process without using an organic solvent harmful to the human body.

The present invention
[1] After mixing organic fine particles with inorganic powder, the organic fine particles are plasticized in a container in the presence of carbon dioxide at a critical temperature or higher and pressure of 4 MPa or higher to remove carbon dioxide. Production method of composite particles fixed to the body surface,
And [2] relates to composite particles for cosmetics obtained by the production method of [1].

  The composite particles produced by the method of the present invention are less agglomerated and the organic fine particles are firmly fixed on the surface of the inorganic powder, so that the organic fine particles can be separated from the inorganic powder even by mechanical energy during stirring and mixing. The composite particles are maintained at high performance even when the composite particles are used for further processing.

  In the present specification, the composite particles are those in which organic fine particles are fixed to the surface of the inorganic powder. Further, the organic fine particles adhering are those that are plastically deformed and adhered in a state of being in close contact with the inorganic powder in a flatter shape than the shape before plasticization. Further, the fixed organic fine particles may be partially fused to each other on the surface of the inorganic powder. In the present invention, “adhesion” means a state in which organic fine particles adhere to the surface of the inorganic powder and are not easily peeled off.

  The method for producing composite particles in which organic fine particles are fixed on the surface of the inorganic powder of the present invention is obtained by mixing the organic fine particles with the inorganic powder and then in the presence of carbon dioxide at a pressure higher than the critical temperature and 4 MPa or higher. One of the major features is that the organic fine particles are plasticized in the container, the organic fine particles are fixed to the surface of the inorganic powder, and the carbon dioxide is removed. If the method of the present invention is used, the organic fine particles are plasticized by contact with carbon dioxide, and the shape is deformed. Therefore, the contact area of the organic fine particles to the surface of the inorganic powder increases, and the organic fine particles to the surface of the inorganic powder. The fixing force of is improved. Further, depending on the plasticization conditions, composite particles in which the fixed organic fine particles are partially fused to each other, that is, a composite in which at least some of the organic fine particles are bonded to each other and fixed on the inorganic powder. Particles can also be obtained. Such composite particles are excellent in that the organic fine particles are firmly fixed to the surface of the inorganic powder.

  As the inorganic powder, a powder which does not substantially dissolve in carbon dioxide at a critical temperature or higher and a pressure of 4 MPa or higher and whose shape and form do not change even when contacting with the carbon dioxide can be used. The average particle size of the inorganic powder is not particularly limited, but is preferably 0.1 to 1,000 μm, more preferably 0.2 to 500 μm, and still more preferably 0.2 to 100 μm. The inorganic powder is not particularly limited and includes, for example, spherical, plate-like, and irregular particles. Among them, plate-like particles are preferable from the viewpoint of good coverage. Examples of the inorganic powder include flaky extender pigments and flaky pearl pigments.

  As used herein, “average particle diameter” means an average diameter calculated from a volume-based particle size distribution measured by a laser diffraction / scattering method.

  Examples of the material constituting the inorganic powder include titanium oxide, silica, mica, talc, kaolin, sericite, zinc oxide, magnesium oxide, aluminum oxide, zirconium oxide, calcium carbonate, magnesium carbonate, magnesium silicate, and anhydrous silica. Examples thereof include acid, barium sulfate, bengara, yellow iron oxide, black iron oxide, carbon black, manganese violet, titanium-coated mica (titanium mica), glass beads, zeolite, and composites thereof. These can be used alone or in admixture of two or more. Among these, at least one inorganic powder selected from the group consisting of mica, titanium mica, talc and barium sulfate is preferable.

  As the organic fine particles, organic substances that swell and plasticize in the presence of carbon dioxide at a critical temperature or higher and a pressure of 4 MPa or higher are used. As the organic substance, a polymer compound is preferably used. Examples of the polymer compound include thermoplastic resins such as acrylic resins such as PMMA (polymethyl methacrylate), polyolefins such as polyethylene and polypropylene, polyesters such as polystyrene, polyvinyl chloride, and polyethylene terephthalate, and polyamide resins such as polycarbonate and nylon. Examples thereof include thermosetting resins such as resins and epoxy resins, phenol resins, and urethane resins. Alternatively, a fluorine-based polymer compound or a silicone-based polymer compound (for example, those described in paragraph numbers [0035] to [0046] of JP-A No. 2002-210356) can also be used.

  The average particle size of the organic fine particles is preferably 1/5 or less, more preferably 1/7 or less, and further preferably 1/10 or less of the average particle size of the inorganic powder, from the viewpoint of adhesion to the inorganic powder. Further, the average particle diameter of the organic fine particles is preferably 1 / 10,000 or more, more preferably 1/1000 or more, and further preferably 1/500 or more of the average particle diameter of the inorganic powder from the viewpoint of the cohesiveness of the organic fine particles.

  The average particle size of the organic fine particles is preferably 0.01 to 100 μm, more preferably 0.05 to 50 μm, still more preferably 0.1 to 20 μm, and particularly preferably 0.1 to 3 μm. The shape of the organic fine particles is preferably spherical, but is not particularly limited.

  From the viewpoint of optical control, the amount of the organic fine particles is preferably 0.001 part by weight or more, more preferably 0.005 part by weight or more, and still more preferably 0.01 part by weight or more with respect to 1 part by weight of the inorganic powder. In order to suppress aggregation of only organic fine particles, the amount is preferably 3 parts by weight or less, more preferably 2 parts by weight or less, and still more preferably 1 part by weight or less with respect to 1 part by weight of the inorganic powder.

  In the present invention, organic fine particles are plasticized in a container in the presence of carbon dioxide at a critical temperature or higher and a pressure of 4 MPa or higher. The “plasticization of organic fine particles” means that the organic fine particles are deformed while maintaining the shape as particles. For example, when the organic fine particles are true spheres before plasticization, the portion in which the organic fine particles are in contact with the inorganic powder becomes flat and comes into contact with the inorganic powder on the surface. Moreover, the aspect in which the part which is not contacting the inorganic powder of organic fine particles maintains a substantially spherical shape is mentioned. Alternatively, when the organic fine particles are adjacent to each other, a part is fused to each other by plasticization, and in some cases, a net-like shape is used.

  In the present invention, the organic fine particles are mixed with the inorganic powder by dry blending or the like before the plasticizing step. When dry blending is performed, in order to prevent aggregation between the organic fine particles and the composite particles, the inorganic powder In addition to the body and organic fine particles, inorganic fine particles may coexist. The average particle size of the inorganic fine particles is smaller than the average particle size of the organic fine particles from the viewpoint of adhesion, and is preferably 0.3 μm or less, more preferably 0.1 μm or less. As the inorganic fine particles, silica particles and the like can be preferably used.

  Similarly, when dry blending, in order to prevent aggregation between organic fine particles and between composite particles, in addition to inorganic powder and organic fine particles, organic or inorganic particles that are not plasticized by carbon dioxide may coexist. Good. From the viewpoint of improving the fluidity of the powder, the average particle size of the organic or inorganic particles is preferably at least 5 times the average particle size of the organic fine particles, and more preferably at least 10 times. Furthermore, the organic particles and the inorganic particles are spherical particles, and it is preferable that the organic fine particles do not adhere.

  In addition, when plasticizing the organic fine particles using carbon dioxide, a fluorine-based polymer compound or a silicone-based polymer compound may coexist in the container to cover a part or all of the composite particles. In this case, for the inorganic powder and / or organic fine particles used as the raw material of the composite particles, a part or all of the particle surface may be previously coated with a fluorine-based polymer compound and / or a silicone-based polymer compound. Good.

  Examples of the fluorine-based polymer compound or the silicone-based polymer compound include those described in paragraph numbers [0035] to [0046] of JP-A No. 2002-210356.

  When plasticizing the organic fine particles in the container in the presence of carbon dioxide at a critical temperature or higher and a pressure of 4 MPa or higher, a plasticizer may be coexisted in order to promote plasticization of the organic fine particles. The plasticizer is preferably one that can be dissolved or emulsified in supercritical carbon dioxide.

  Examples of the plasticizer include p-methoxycinnamic acid 2-ethylhexyl, phthalic acid ester, phosphoric acid ester, aliphatic monobasic acid ester, aliphatic dibasic acid ester, dihydric alcohol ester, oxyacid ester and the like. .

  In addition, when the organic fine particles are a substance that is not easily plasticized by carbon dioxide, the plasticizer may be promoted by adding a co-solvent that is harmless to the human body as an entrainer. The cosolvent is preferably a polar solvent, and examples thereof include alcohol, acetone, ethyl acetate, methyl ethyl ketone, and water. The alcohol is preferably ethanol and 1-propanol, more preferably ethanol.

  High-pressure carbon dioxide exhibits a wide range of solubility in polymer compounds. Organic fine particles are swollen by the dissolution (sorption) of carbon dioxide, and as a result, the plasticity of the organic fine particles is greatly increased even at a temperature below its melting point or glass transition temperature (Tg). For this reason, it is possible to increase the plasticity of the organic fine particles by bringing the organic fine particles into contact with high pressure, particularly carbon dioxide of 4 MPa or more, and increasing the contact area to the surface of the inorganic powder by deforming the organic fine particles. This makes it possible to achieve a strong fixation.

  On the other hand, if the pressure of carbon dioxide is decreased, the solubility of carbon dioxide in organic fine particles can be drastically lowered, so that the organic fine particles and carbon dioxide can be separated only by a decompression operation.

  In the present invention, first, organic fine particles are mixed with inorganic powder. For example, it is preferable to mix inorganic powder and organic fine particles in advance with a high-speed fluid mixer or the like and perform physical fixation by stirring force.

  Regarding the preparation of carbon dioxide, carbon dioxide is introduced until the powder is in a good fluidized state at a temperature below the melting point or glass transition point of the organic fine particles in the presence of carbon dioxide. After carbon dioxide is introduced, stirring is performed and the temperature is raised to a temperature at which the organic fine particles are plasticized, whereby the cohesiveness of the particles can be improved.

  The temperature at which the organic fine particles are plasticized in the presence of carbon dioxide depends on the plasticity of the organic fine particles, but is higher than the critical temperature of carbon dioxide from the viewpoint of efficient plasticization.

  Further, the pressure when plasticizing the organic fine particles in the presence of carbon dioxide depends on the plasticity of the organic fine particles, but is 4 MPa or more, and more preferably 10 MPa or more. Since the density of carbon dioxide increases at high pressure, the pressure is preferably higher from the viewpoint of improving the fluidity of the inorganic powder and composite particles and improving the agglomeration property of the particles. The upper limit of the pressure is preferably 50 MPa or less, and more preferably 40 MPa or less, from the viewpoint of efficient equipment cost, carbon dioxide removal and decompression.

  The time for plasticizing the organic fine particles in the presence of carbon dioxide depends on the plasticity of the organic fine particles, but is preferably 1 minute to 20 hours, more preferably 5 minutes to 5 hours, and particularly preferably 15 minutes to 3 hours. is there.

  By stirring the inside of the container during the plasticizing step, the fluidity of the inorganic powder and the composite particles becomes good, and the aggregation property of the particles can be improved.

  After the organic fine particles are fixed on the surface of the inorganic powder, carbon dioxide is removed.

  As a method of obtaining composite particles by removing carbon dioxide, a method of obtaining composite particles in the container by depressurizing the inside of the container, by discharging the resulting mixture outside the container, And a method for obtaining composite particles.

In the method in which the inside of the container is depressurized to obtain composite particles in the container, after the organic fine particles are fixed to the surface of the inorganic powder, for example, the valve provided in the container is opened to reduce the pressure in the container to atmospheric pressure. The composite particles in the container can be separated from the carbon dioxide by reducing the pressure to about 1.

  From the viewpoint of improving the cohesiveness of the particles, it is preferable to discharge the carbon dioxide from the container and reduce the pressure to atmospheric pressure after cooling to the melting point of the organic fine particles or the glass transition point in the presence of carbon dioxide.

  The time required to reduce the pressure in the container to atmospheric pressure depends on the apparatus, but is preferably 2 seconds to 20 hours, and more preferably 5 seconds to 10 hours.

  A liquid phase of carbon dioxide may or may not be generated during the decompression step, but if the average particle size of the inorganic powder used is 20 μm or less, aggregation due to capillary force may occur. It is better to avoid generating a liquid phase of carbon dioxide.

  In the method of separating the composite particles and carbon dioxide by discharging the obtained mixture out of the container to obtain composite particles, the mixture in the container is discharged out of the container through a nozzle or the like. The carbon dioxide can be separated and removed from the mixture instantly after leaving the nozzle or the like, and composite particles without agglomeration can be produced. The discharge conditions are not particularly limited, but the temperature after discharge is preferably below the melting point of the organic fine particles or the glass transition point.

Comparative Example 1
Talc [manufactured by Yamaguchi Mica Industry Co., Ltd., average particle size: 10 μm] 7.00 g and spherical polymethyl methacrylate (hereinafter abbreviated as PMMA) [manufactured by Soken Chemical Co., Ltd., average particle size 0.3 μm] 3.00 g Was mixed in a high-speed fluidized mixer super mixer [trade name: Piccolo SMP-2, internal volume 0.3 L, manufactured by Kawata Co., Ltd.] and mixed at 3000 r / min for 5 minutes to obtain a mixed powder.

  Scanning electron micrographs of raw material talc and PMMA are shown in FIG. 2 (magnification: 5000 times) and FIG. 3 (magnification: 10000 times), respectively. Further, a scanning electron micrograph of the obtained mixed powder is shown in FIG. 4 (magnification: 10,000 times). From the micrograph shown in FIG. 4, it can be seen that in the mixed powder of Comparative Example 1, the substantially spherical PMMA particles adhere to the talc surface while remaining almost spherical.

Example 1
Using the apparatus shown in FIG. 1, composite particles were produced by the following procedure.
10.00 g of the mixed powder obtained in Comparative Example 1 was filled into an autoclave 10 (internal volume: 500 mL, manufactured by AKICO).

  After filling, carbon dioxide gas or liquefied carbon dioxide was supplied from the cylinder 1 and passed through the filter 2 to remove dust in the carbon dioxide. Next, the carbon dioxide was condensed by the condenser 3 through which the refrigerant controlled to −5 ° C. was passed from the cooler 5, and the pressure was increased by the booster pump 4 in which the pump head was cooled. The pressure at the time of pressure increase was measured by the pressure gauge 6a. In order to ensure safety, a safety valve 7a is disposed downstream of the pressure gauge 6a. The pressure was adjusted with a pressure holding valve V-1.

  While rotating the agitator 9, the valve V-2 is opened and carbon dioxide is passed through the preheater 8 and preheated to a predetermined temperature and sent to the autoclave 10 to which the safety valve 7b is attached via the valve V-3. Carbon was introduced. Using the cartridge heater 12, the temperature in the autoclave 10 was adjusted by the temperature controller 13, and the temperature and pressure in the cell were adjusted to a temperature of 296 K and a pressure of 6.2 MPa by the thermometer 11 and the pressure gauge 6b, respectively. Thereafter, the temperature in the autoclave 10 was further adjusted by the temperature controller 13, and the temperature and pressure in the cell were adjusted to a temperature of 353 K and a pressure of 25.0 MPa by the exhaust valve V-4, the thermometer 11 and the pressure gauge 6b, respectively. It was kept for 0.5 hours under these conditions.

  The exhaust valve V-4 was opened, exhausted from the exhaust line 15, and decompressed for 10 minutes. At this time, the temperature in the container decreased, but the temperature in the container was adjusted so as not to become 313K or lower, and the temperature in the container at the end of the decompression was 326K. In addition, the heater 14 was heated to prevent the exhaust line from freezing. In addition, the composite filter that slightly leaked from the exhaust line 15 was captured by the bag filter 16. After reducing the container pressure in the autoclave 10 to atmospheric pressure, composite particles 17 were obtained from the autoclave 10.

  A scanning electron micrograph of the obtained composite particles is shown in FIG. 5 (magnification: 10000 times). From the micrograph shown in FIG. 5, it can be seen that composite particles in which PMMA is fixed on talc particles are obtained. In addition, the PMMA particles that were spherical before fixation were flattened, and some of the adjacent PMMA particles were fused together, indicating that plasticization occurred.

Example 2
The composite was made in the same manner as in Example 1 except that 7.00 g of talc in Example 1 was changed to 8.00 g and 3.00 g of PMMA was changed to 2.00 g. A scanning electron micrograph of the obtained composite powder is shown in FIG. 6 (magnification: 10000 times). From the photomicrograph shown in FIG. 6, it can be seen that the PMMA particles that were spherical before plasticization were flattened by plasticization, and the adjacent PMMA particles were partially fused.

Comparative Example 2
Mixed powder as in Comparative Example 1, except that the talc of Comparative Example 1 was changed to 21.90 g of titanium mica (ECKART Gmbh & Co. KG, average particle size: 45 μm) and PMMA 3.00 g to 1.10 g. Got. A scanning electron micrograph of the raw material titanium mica is shown in FIG. 7 (magnification: 1000 times). Scanning electron micrographs of the obtained mixed powder are shown in FIG. 8 (magnification: 10000 times) and FIG. 9 (magnification: 30000 times). It can be seen from the micrographs shown in FIGS. 8 and 9 that the PMMA particles that were almost spherical were attached to the titanium mica surface while remaining almost spherical.

Comparative Example 3
A mixed powder was obtained in the same manner as in Comparative Example 2, except that 21.90 g of titanium mica in Comparative Example 2 was changed to 20.90 g and 1.10 g of PMMA was changed to 2.10 g. When the obtained mixed powder was observed with a scanning electron microscope, it was found that PMMA particles that were substantially spherical were adhered to the titanium mica surface while remaining almost spherical.

Comparative Example 4
1.10 g of PMMA in Comparative Example 2 was changed to 0.84 g, and hexamethylene diisocyanate / trimethylol hexyl lactone cross-linked polymer (hereinafter abbreviated as D-800) [Toyo Pigment Co., Ltd., average particle size 6.0 μm] 1.05 g A mixed powder was obtained in the same manner as in Comparative Example 2 except that. A scanning electron micrograph of the obtained mixed powder is shown in Fig. 10 (magnification: 3000 times). From the micrograph shown in FIG. 10, it was found that PMMA particles that were almost spherical were adhered to the titanium mica surface while remaining almost spherical, and PMMA was not adhered to D-800.

Example 3
The autoclave 10 was filled with 23.00 g of the mixed powder obtained in Comparative Example 2, and composited in the same manner as in Example 1. Thereafter, the pressure was reduced for 4 minutes to obtain composite particles. The temperature in the container at the end of the decompression was 322K. Scanning electron micrographs of the obtained composite powder are shown in FIG. 11 (magnification: 10000 times) and FIG. 12 (magnification: 30000 times). From the micrographs shown in FIG. 11 and FIG. 12, it can be seen that the PMMA particles that were almost spherical before plasticization were flattened by plasticization and fixed on the titanium mica particles in a wide area. Further, it can be seen that for some PMMA particles, adjacent particles are fused.

Example 4
Introducing and maintaining carbon dioxide in the same manner as in Example 1 except that 14.90 g of the mixed powder obtained in Comparative Example 2 was charged into the autoclave 10 and the pressure at the end of charging of carbon dioxide was adjusted to 6.0 MPa. Went. After that, before discharging the carbon dioxide in the container, the temperature in the container was lowered to 300 K, and a liquid phase of carbon dioxide was generated in the system. At this time, the internal pressure was 6.8 MPa. Thereafter, the pressure was reduced to atmospheric pressure in 4 minutes to obtain composite particles. The temperature in the container at the end of the decompression was 267K.

  A scanning electron micrograph of the obtained composite powder is shown in FIG. 13 (magnification: 10000 times). From the photomicrograph shown in FIG. 13, it can be seen that the PMMA particles that were almost spherical before plasticization were flattened by plasticization and fixed on the titanium mica particles in a wide area. Further, it can be seen that for some PMMA particles, adjacent particles are fused.

Example 5
Introducing and maintaining carbon dioxide in the same manner as in Example 1 except that 15.48 g of the mixed powder obtained in Comparative Example 4 was charged into the autoclave 10 and the pressure at the end of charging of carbon dioxide was adjusted to 6.0 MPa. Went. Thereafter, the temperature in the container was lowered to 318 K before discharging the carbon dioxide in the container. At this time, the internal pressure was 12.7 MPa. Then, after the stirring rotation speed was reduced to 100 r / min, the pressure was reduced to atmospheric pressure in 10 minutes to obtain composite particles. The temperature in the container at the end of the decompression was 310K.

  A scanning electron micrograph of the obtained composite powder is shown in FIG. 14 (magnification: 3000 times). From the photomicrograph shown in FIG. 14, it can be seen that the PMMA particles that were almost spherical before plasticization were flattened by plasticization and fixed on the titanium mica particles in a wide area. Further, it can be seen that for some PMMA particles, adjacent particles are fused.

Moreover, it can be seen from this micrograph that PMMA is not attached to D-800 in the obtained composite powder. This D-800 expresses the effect of suppressing aggregation of the composite particles. In fact, when the average particle size of titanium mica is 45 μm, the average particle size of the composite particles obtained in Example 3 is 53 μm, whereas the average particle size of the composite particles obtained in Example 5 is Since the diameter is 47 μm, according to Example 5, it can be seen that D-800 suppresses the aggregation of the composite particles.

  The manufacturing conditions of Examples 1 to 5 and Comparative Examples 1 to 4 are summarized in Tables 1 and 2 below.

  The amount of surface reflected light of the composite particles obtained in Examples 1 to 3 and the mixed powders obtained in Comparative Examples 1 to 3 was measured as follows.

(Measurement of the amount of reflected light on the surface)
First, the surface reflected light amount is measured for each sample as follows.
On a 10cm x 5cm polyurethane black artificial leather, the formula (I):

(Where m = 1341, n = 5 and x = 27)
A 30% ethanol solution of oxazoline-modified silicone (molecular weight: 110000) represented by the formula is applied at a film thickness of 50 μm. After the coating film has dried, 5 mg of the sample powder is applied, and measurement is performed using a two-dimensional variable angle spectrophotometer GCMS-3 manufactured by Murakami Color Research Laboratory under light receiving conditions of 2 ° field of view with C light. . The measurement condition is that the angle formed by the incident angle and the light receiving angle is fixed at 20 °, and the angle θ formed by the bisector of the angle formed by the incident angle and the light receiving angle and the normal line of the sample is −50 °, 0 °, And the angle of the sample is changed so as to be 50 °, and the amount of reflected light is measured. When θ is 0 °, specular reflection light is mainly measured, and when θ is 50 ° or −50 °, diffuse reflection light is mainly measured. The difference in the amount of reflected light between θ = 0 ° and θ = 50 ° or −50 ° is defined as the surface reflected light amount.

  After measuring the surface reflected light amount of the composite particles obtained in Examples 1 to 3 and the mixed powder obtained in Comparative Examples 1 to 3, the surface reflected light amount of the inorganic powder to which PMMA is not attached is 100%. The relative value was defined as the surface reflected light intensity. The results are shown in Table 3.

  As shown in Table 3, it can be seen that the surface reflected light intensity of the mother particles can be lowered by fixing PMMA. Further, as can be seen from the comparison between the composite particles of Example 1 and the mixed powder of Comparative Example 1 and the comparison of the composite particles of Example 3 and the mixed powder of Comparative Example 2, comparison was made with the same PMMA addition amount. In this case, it can be seen that the composite particles of the example have a higher reduction rate of the surface reflected light intensity and higher efficiency than the mixed powder of the comparative example.

  Next, the adhesion strength of the composite particles obtained in Examples 1 to 3 and the mixed powder obtained in Comparative Examples 1 to 3 was evaluated as follows.

(Adhesion strength evaluation method)
On a 10cm x 5cm polyurethane black artificial leather, the formula (I):

(In the formula, m is 1341, n is 5, and x is 27)
A 30% ethanol solution of oxazoline-modified silicone represented by the formula (molecular weight: 110000) is applied to a thickness of 50 μm. After the coating film has dried, 5 mg of the sample powder is applied, and the adhesion state of the composite powder or mixed powder inorganic powder and organic fine particles is confirmed by scanning electron microscope observation.

  Scanning electron micrographs showing the fixed state of the organic fine particles on the inorganic powders of Comparative Example 1, Example 1 and Example 2 obtained using talc as the inorganic powder are shown in FIGS. c). Further, scanning electron micrographs showing the fixed state of the organic fine particles on the inorganic powders of Comparative Example 2, Comparative Example 3, and Example 3 obtained using titanium mica as the inorganic powder are shown in FIG. ) To (f).

  From the micrograph shown in FIG. 15, the mixed powder obtained in each comparative example, the organic fine particles are peeled off from the surface of the inorganic powder after being applied to black leather, the composite obtained in each example It can be seen that the particles are firmly bonded with the inorganic powder and the organic fine particles even after being applied to the black leather, and they have a strong fixing force.

Example 6
Powder Foundation Using the composite powder obtained in Example 3, a powder foundation was produced by a conventional method with the formulation shown in Table 4.

  The powder foundation obtained in Example 6 had a feeling of glare, a transparency, and a natural gloss.

  According to the present invention, water repellency, oil repellency, optical properties, UV protection, touch, safety, activity, color tone, dispersion stability, weather resistance, paint, ink jet printer ink, toner, cosmetics, etc. It is possible to provide composite particles that can be suitably used for the above.

It is a schematic explanatory drawing which shows one embodiment of the apparatus used for the method of this invention. It is a scanning electron micrograph (magnification: 5000 times) which shows the particle structure of the raw material talc used in Comparative Example 1, Example 1 and Example 2. It is a scanning electron micrograph (magnification: 10000 times) showing the particle structure of the raw material PMMA used in Examples and Comparative Examples. 2 is a scanning electron micrograph (magnification: 10000 times) showing the particle structure of the mixed powder obtained in Comparative Example 1. 2 is a scanning electron micrograph (magnification: 10000 times) showing the particle structure of the composite particles obtained in Example 1. FIG. 4 is a scanning electron micrograph (magnification: 10000 times) showing the particle structure of the composite particles obtained in Example 2. FIG. It is a scanning electron micrograph (magnification: 1000 times) which shows the particle structure of the raw material titanium mica used in Examples 3-5 and Comparative Examples 2-4. 4 is a scanning electron micrograph (magnification: 10000 times) showing the particle structure of the mixed powder obtained in Comparative Example 2. 4 is a scanning electron micrograph (magnification: 30000 times) showing the particle structure of the mixed powder obtained in Comparative Example 2. 6 is a scanning electron micrograph (magnification: 3000 times) showing the particle structure of the composite particles obtained in Comparative Example 4. 4 is a scanning electron micrograph (magnification: 10000 times) showing the particle structure of the composite particles obtained in Example 3. FIG. 4 is a scanning electron micrograph (magnification: 30000 times) showing the particle structure of the composite particles obtained in Example 3. FIG. 4 is a scanning electron micrograph (magnification: 10000 times) showing the particle structure of the composite particles obtained in Example 4. 6 is a scanning electron micrograph (magnification: 3000 times) showing the particle structure of the composite particles obtained in Example 5. FIG. It is a scanning electron micrograph (magnification: 4000 times) which shows the adhesion state of the organic fine particle on the inorganic powder of the particle | grains obtained by the comparative example 1 using talc as an inorganic powder. It is a scanning electron micrograph (magnification: 4000 times) which shows the fixed state of the organic fine particle on the inorganic powder of the particles obtained in Example 1 using talc as the inorganic powder. It is a scanning electron micrograph (magnification: 4000 times) which shows the fixed state of the organic fine particle on the inorganic powder of the particles obtained in Example 2 using talc as the inorganic powder. It is a scanning electron micrograph (magnification: 2000 times) which shows the adhesion state of the organic fine particle on the inorganic powder of the particles obtained in Comparative Example 2 using titanium mica as the inorganic powder. It is a scanning electron micrograph (magnification: 2000 times) which shows the adhesion state of the organic fine particle on the inorganic powder of the particle | grains obtained in the comparative example 3 using titanium mica as an inorganic powder. It is a scanning electron micrograph (magnification: 2000 times) which shows the fixed state of the organic fine particle on the inorganic powder of the particles obtained in Example 3 using titanium mica as the inorganic powder.

Explanation of symbols

1 Cylinder 2 Filter 3 Condenser 4 Booster Pump 5 Cooler
6a Pressure gauge
6b pressure gauge
7a Safety valve
7b Safety valve 8 Preheater 9 Stirrer
10 autoclave
11 Thermometer
12 cartridge heater
13 Temperature controller
14 heater
15 exhaust line
16 bug filters
17 composite particles
V-1 Holding valve
V-2 valve
V-3 valve
V-4 Exhaust valve

Claims (7)

  After mixing the organic fine particles with the inorganic powder, the organic fine particles are plasticized in the container in the presence of carbon dioxide at a critical temperature or higher and a pressure of 4 MPa or higher to remove the carbon dioxide. A method for producing fixed composite particles.   The method for producing composite particles according to claim 1, wherein the average particle size of the organic fine particles is 1/10000 to 1/5 of the average particle size of the inorganic powder.   The method for producing composite particles according to claim 1 or 2, wherein the inorganic powder has a plate shape.   The method for producing composite particles according to any one of claims 1 to 3, wherein the amount of the organic fine particles is 0.001 to 3 parts by weight with respect to 1 part by weight of the inorganic powder.   The method for producing composite particles according to any one of claims 1 to 4, wherein after the organic fine particles are plasticized, the inside of the container is decompressed to obtain composite particles in the container.   The method for producing composite particles according to any one of claims 1 to 5, wherein organic or inorganic particles having an average particle size of 5 times or more of the average particle size of the organic fine particles coexist to obtain composite particles. Cosmetic composite particles obtained by the production method according to claim 1.

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