JP2010120824A - Weakly flocculated powder and inorganic particle-organic polymer composite paste - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide weakly flocculated powder of inorganic particles, which can be dispersed uniformly in a polymer matrix composed of an organic polymer. <P>SOLUTION: The weakly flocculated powder is obtained by freeze-drying the slurry containing inorganic particles 10 obtained by crumbling inorganic raw material powder in a mill process without damaging the surfaces of particles. When the weakly flocculated powder is mixed and kneaded with the organic polymer to produce inorganic particle 10-organic polymer composite paste, the inorganic particle 10 can be dispersed uniformly in the polymer matrix even though the surface of the inorganic particle 10 is not modified chemically. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a soft agglomerated powder and an inorganic particle-organic polymer composite paste. More specifically, a soft agglomerated powder of inorganic particles that can be uniformly dispersed in a polymer matrix made of an organic polymer without subjecting the surface of the inorganic particles to a chemical reaction treatment, and an inorganic containing such a soft agglomerated powder. The present invention relates to a particle-organic polymer composite paste.

  In order to obtain a composite material with excellent properties, polymer is prepared by mixing and kneading inorganic particles with properties such as high refractive index, high thermal conductivity, high dielectric constant, and ultraviolet absorption in a high-processability polymer resin (organic polymer). Dispersed in. In this case, a method is adopted in which a chemical substance of a coupling agent having a silane group, a sulfonic acid group, a mercapto group, etc. is modified on the surface of the inorganic particles, and the affinity between the inorganic particles and the organic polymer is controlled and dispersed. (For example, see Patent Documents 1 to 3).

  Also, after dispersing inorganic particles in a solvent in advance, the organic polymer dissolved in the solvent is mixed, and then the mixed solvent is removed and the organic polymer is cured, whereby an inorganic particle dispersed composite material A manufacturing method has also been proposed (see, for example, Patent Documents 4 and 5).

JP 2004-331740 A Japanese Patent Laid-Open No. 10-139928 JP 2003-105094 A JP 2005-347316 A JP 2007-291184 A

  However, the composition of the composite material to be developed varies widely, and in the adjustment method by chemical modification of the inorganic particle surface, it is necessary to consider the type and amount of modifier and the reaction method depending on the combination of materials. There is a problem that the manufacturing cost is increased. In addition, there is a need to use a chemical substance to finally make it harmless to the environment, and there is a problem that the energy cost and the environmental load related to the production are increased.

  In addition, in the method in which the inorganic particles are dispersed in the solvent and then the organic polymer is added to remove the solvent, the solvent remains in the organic polymer, so that the obtained composite paste is cured to obtain a composite material. At this time, there is a problem that pores are formed by the remaining solvent, which deteriorates the characteristics of the composite material.

  Furthermore, recently, it is a transparent conductive film, semiconductor-related member, optical member, heat dissipation member, etc. that meet the high demands of the rapidly developing information, home appliances, automobile industry, etc. In individual materials such as polymers, metals, ceramics, etc. Reciprocal functions that are difficult to achieve, such as high particle content and fluidity, insulation and heat conduction, insulation and high refractive properties, are desired in combination with productivity, There is a strong demand for improved properties of composite materials and low environmental load manufacturing processes.

  However, when inorganic particles / powder such as ceramics are mixed into the organic polymer, if the amount of inorganic particles added increases, not only the added inorganic particles aggregate and the dispersibility decreases, but the fluidity of the mixture is remarkably increased. It will decline. At present, it is difficult to mix inorganic particles / powder with a high powder content to develop moldability and processability, which are one of the characteristics of organic polymers.

  The present invention has been made in view of such problems of the prior art, and the problem is to softly aggregate inorganic particles that can be uniformly dispersed in a polymer matrix made of an organic polymer. The object is to provide a powder and an inorganic particle-organic polymer composite paste containing such soft agglomerated powder.

  As a result of intensive studies to achieve the above-mentioned problems, the inventors of the present invention do not damage the particle surface of the inorganic raw material powder in the mill process, that is, the same damage state as the surface state of the inorganic raw material powder used as the raw material. The present invention was completed by finding that the above problems can be achieved by using a soft agglomerated powder obtained by freeze-drying a slurry containing inorganic particles obtained by crushing. It came to do.

  That is, according to the present invention, the following soft agglomerated powder, inorganic particle-organic polymer composite paste using the soft agglomerated powder, and a composite material comprising the inorganic particle-organic polymer composite paste are provided.

[1] A soft agglomerated powder obtained by freeze-drying a slurry containing inorganic particles obtained by pulverizing an inorganic raw material powder by a mill process without damaging the particle surface.

[2] The soft agglomerated powder according to [1], wherein the crushing strength is reduced in a range of 1 to 50% with respect to the crushing strength of the inorganic raw material powder, and the crushing strength is 1 to 30 MPa. .

[3] The above [1] or [2], wherein the slurry is obtained by pulverizing the inorganic raw material powder by the mill process using a wet jet mill so that a collision pressure between the slurries becomes 50 to 300 MPa. ] The soft-aggregated powder described in the above.

[4] The soft agglomerated powder according to any one of [1] to [3] obtained by freeze-drying the slurry obtained by adding a dispersant to the inorganic raw material powder and pulverizing the slurry.

[5] Inorganic particle-organic polymer containing the soft agglomerated powder according to any one of [1] to [4] and an organic polymer, wherein a content ratio of the soft agglomerated powder is 1 to 75% by volume. Composite paste.

[6] The inorganic particle-organic polymer composite paste according to [5], which is produced without subjecting the surface of the inorganic particles constituting the soft agglomerated powder to chemical modification.

[7] The condition that the shear force of the organic polymer is stronger than the cohesive force of the soft agglomerated powder is set, the soft agglomerated powder and the organic polymer are mixed and kneaded, and the soft agglomerated powder is mixed in the polymer matrix. The inorganic particle-organic polymer composite paste according to [5] or [6], in which is dispersed.

[8] The inorganic particles-organic according to [7], wherein the soft agglomerated powder and the organic polymer are mixed and the soft agglomerated powder is dispersed in the polymer matrix at a kneading speed of 50 to 5000 revolutions. Polymer composite paste.

[9] The fluidity of the raw material powder composite paste composed of the inorganic raw material powder and the organic polymer for producing the soft agglomerated powder is improved in the range of 10 to 90%. [8] The inorganic particle-organic polymer composite paste according to any one of [8].

[10] The inorganic particle-organic polymer composite paste according to [8] or [9], wherein the organic polymer has a viscosity of 0.1 to 100,000 Pa · s in kneading.

[11] The inorganic particle-organic polymer composite according to any one of [5] to [10], wherein the inorganic particles constituting the soft agglomerated powder dispersed in the organic polymer are present in the polymer matrix in a primary particle state. paste.

[12] The surface state of the inorganic particles constituting the soft agglomerated powder dispersed in the organic polymer is not damaged as much as the particles constituting the inorganic raw material powder for producing the soft agglomerated powder. The inorganic particle-organic polymer composite paste according to any one of [5] to [11].

[13] A composite material comprising the inorganic particle-organic polymer composite paste according to any one of [5] to [12].

  The soft agglomerated powder of the present invention can uniformly disperse the inorganic particles constituting the soft agglomerated powder in a polymer matrix made of an organic polymer. That is, it solves the problem of decrease in fluidity due to the high content of powder composed of inorganic particles, and improves the dispersibility of inorganic particles even with a high powder content of 1 to 75% by volume, for example. It is possible to obtain an inorganic particle-organic polymer composite paste having high fluidity and easy moldability.

  In addition, since the soft agglomerated powder of the present invention can be uniformly dispersed in the organic polymer without chemically modifying the surface of the inorganic particles, for example, in the manufacturing process of the inorganic particle-organic polymer composite paste or composite material, It is not necessary to use chemical substances, and an environmentally harmonious manufacturing process can be realized. The “chemical modification” described above refers to performing a chemical reaction treatment using a chemical substance on the surface of the inorganic particles.

  In addition, the inorganic particle-organic polymer composite paste of the present invention has a low adsorption affinity and high fluidity between the inorganic particles and the organic polymer, so that the inorganic particles are well-dispersed in the polymer matrix and are easily moldable. -Organic polymer composite paste.

  Furthermore, the composite material of the present invention is composed of the inorganic particle-organic polymer composite paste of the present invention, which is excellent in productivity and processability, and each member using this composite material and high performance of various products. Can be expected.

  BEST MODE FOR CARRYING OUT THE INVENTION The best mode for carrying out the present invention will be described below, but the present invention is not limited to the following embodiment, and is based on the ordinary knowledge of those skilled in the art without departing from the gist of the present invention. It should be understood that modifications and improvements as appropriate to the following embodiments also fall within the scope of the present invention.

[1] Soft agglomerated powder:
First, an embodiment of the soft agglomerated powder of the present invention will be specifically described. The soft agglomerated powder of this embodiment is a soft agglomerated powder obtained by freeze-drying a slurry containing inorganic particles obtained by pulverizing an inorganic raw material powder without damage to the particle surface by a mill process.

  Such a soft agglomerated powder is mixed and kneaded with an organic polymer, and the soft agglomerated powder is crushed using the shearing force of the organic polymer to disperse the inorganic particles in the form of primary particles in the polymer matrix. The made inorganic particle-organic polymer composite paste can be produced satisfactorily. That is, it solves the problem of decrease in fluidity due to the high content of powder composed of inorganic particles, and improves the dispersibility of inorganic particles even with a high powder content of 1 to 75% by volume, for example. It is possible to obtain an inorganic particle-organic polymer composite paste having high fluidity and easy moldability.

  Generally, the crushing strength of the particle aggregate (aggregated powder) is represented by the following formula (1).

  σ = 2 (1-ε) ku / d (1)

  Where σ is the crushing strength, ε is the porosity of the structure (particle aggregate), k is the coordination number of the particles, u is the surface energy of the particles, and d is the primary particle diameter. Show.

  From the above equation (1), if the porosity ε of the structure is the same, the crushing strength σ decreases as the surface energy u of the particles decreases. In the production of the conventional inorganic particle-organic polymer composite paste, chemically modifying the surface of the inorganic particles constituting the agglomerated powder has the meaning of reducing the surface energy u of the particles, but the soft agglomerated powder of this embodiment In view of environmental load, it is possible to provide a soft agglomerated powder capable of producing an inorganic particle-organic polymer composite paste without chemical modification.

  In general, since inorganic powder forms an aggregated state, a milling method using a ball medium such as a ball mill or a planetary ball mill is used as a crushing process for dispersion. Dispersed particles produced by such a method are known to agglomerate with time, and inorganic particles dispersed by the crushing process may agglomerate again with time. The present inventors have succeeded in dispersing inorganic particles having a low agglomeration property by changing the surface state of the particles by a method of crushing the agglomerated powder, that is, a mill method (see, for example, JP-A-2006-248876). reference).

  The soft agglomerated powder of this embodiment is obtained by pulverizing the raw material agglomerated powder once by a mill process and freeze-drying the slurry. In particular, by using a wet jet mill which is one of the mill methods in the mill process, the surface of the inorganic particles can be crushed without damage. Here, FIG. 1A is a transmission electron microscope (TEM) photograph of the particle surface after the wet jet mill, and FIG. 1B is a transmission electron microscope (TEM) photograph of the particle surface after the ball mill. As shown in FIG. 1A, it can be confirmed that the particle surface after the wet jet mill is in an undamaged state. As shown in FIG. 1B, when a ball mill used in a conventional general mill process is used, the energy of collision with the powder of the ball is large, so that the surfaces of the inorganic particles 10 are in a damaged state. In some cases, it may be difficult to realize the “state in which the particle surface is not damaged” in the soft agglomerated powder of the present embodiment.

  The wet jet mill described above prepares a slurry in which an inorganic raw material powder is mixed in a solvent such as water, and the slurry collides from both directions in a crushing chamber (pulverization chamber) or the slurry. Is collided with the wall of the crushing chamber to crush the inorganic raw material powder. However, the method for crushing the inorganic raw material powder in the soft agglomerated powder of the present embodiment is not limited to the wet jet mill as long as the surface of the milled inorganic particles is not damaged. For example, as a mill process for crushing inorganic raw material powder, in addition to the wet jet mill, for example, crushing by ultrasonic waves, crushing by bead mill, and the like can be mentioned. Even by such a method, the inorganic raw material powder can be crushed without damaging the surface of the inorganic particles.

  The reaggregation property of the dispersed particles is larger in the particles adjusted by the ball mill than in the particles adjusted by the wet jet mill, and the surface energy u of the particles represented by the above formula (1) is subjected to the wet jet mill treatment. The particles are smaller.

  In addition, “the state where the particle surface is not damaged” means a state where there is no damage as much as the surface damage state of the raw material agglomerated powder (inorganic raw material powder) to be crushed by the mill process. It can be defined by the surface roughness of the crushed particles. Further, “a state in which the surface of the raw material agglomerated powder is not damaged to the same extent” means that the particles after pulverization with respect to the surface roughness of the particles constituting the raw material agglomerated powder (ie, the inorganic raw material powder) The surface roughness is the same, or the surface roughness is in the range of 0 to 5%. As a result, when the surface of the inorganic particles is damaged, functional groups different from the composition of the raw material increase by 5% or more on the particle surface. For example, when the particle surface is damaged (damaged), the state becomes unstable. More specifically, when an inorganic oxide particle is damaged on the particle surface in an aqueous system such as wet jet milling, a hydroxyl group may be formed on the particle surface.

  As the inorganic raw material powder used for the soft agglomerated powder of the present embodiment, metal powder, intermetallic compound powder, ceramic powder, and mixed powders thereof can be used, and the kind of inorganic raw material powder to be used is not particularly limited. Absent. Examples of the ceramic powder include alumina such as oxide, carbide, and nitride, zirconia, aluminum nitride, boron nitride, silicon nitride, silicon carbide, barium titanate, silica, and titanium dioxide.

  In the crushing of the inorganic raw material powder in the agglomerated state, it may be crushed after preparing a slurry containing a high powder content using a dispersant generally used widely in the ceramics industry. Of course, crushing may be performed without using the above-described dispersant. In addition, as a dispersing agent, conventionally well-known dispersing agents, such as polyacrylic acid ammonium salt, polyethyleneimine, polymethacrylic acid ammonium salt, can be used suitably, for example.

  The soft agglomerated powder of this embodiment can be obtained by freeze-drying the slurry containing inorganic particles obtained by crushing without damaging the particle surface in this way. By such lyophilization, the action of capillary force during drying can be reduced, and the cohesive force between inorganic particles can be suppressed.

  In addition, there is no restriction | limiting in particular about the method of freeze-drying a slurry, For example, the method of freezing with liquid nitrogen etc. for a short time can be mentioned. The preferable temperature in freezing is −3 ° C. or lower, more preferably −100 ° C. or lower. After rapidly freezing at such a temperature, it is preferable to dry under reduced pressure by sublimating the solvent in a vacuum state. The degree of vacuum at this time is preferably 0.01 Pa or more and 200 Pa or less. By comprising in this way, the cohesion force between inorganic particles can be suppressed favorably, and re-aggregation of particles can also be prevented by freezing rapidly.

  The soft agglomerated powder of this embodiment has a reduced crushing strength in the range of 1 to 50% with respect to the crushing strength of the inorganic raw material powder (that is, the crushing strength before crushing). The crushing strength is preferably 1 to 30 MPa. By comprising in this way, the inorganic particle which comprises soft-aggregated powder can be favorably disperse | distributed when manufacturing an inorganic particle-organic polymer composite paste.

  In addition, when the inorganic raw material powder is crushed by a mill process using a wet jet mill, the powder is preferably crushed so that the collision pressure between the slurries is 50 to 300 MPa, and is 100 to 250 MPa. More preferably, it is crushed. By comprising in this way, it can disintegrate favorably without the damage of the inorganic particle surface. If the collision pressure between the slurries is less than 50 MPa, the inorganic raw material powder may not be sufficiently crushed, and if it exceeds 300 MPa, the surface of the inorganic particles may be damaged.

[2] Inorganic particle-organic polymer composite paste:
Next, one embodiment of the inorganic particle-organic polymer composite paste of the present invention will be specifically described. The inorganic particle-organic polymer composite paste of the present embodiment contains the soft agglomerated powder of the present invention described so far and an organic polymer, and the content of the soft agglomerated powder is 1 to 75% by volume. It is a particle-organic polymer composite paste.

  Inorganic particles of the present embodiment-The organic polymer composite paste has a low adsorption affinity between the inorganic particles and the organic polymer and a high fluidity. Therefore, the inorganic particles are well-dispersed in the polymer matrix. Organic polymer composite paste.

  As an organic polymer used for the inorganic particle-organic polymer composite paste of the present embodiment, for example, used in the production of conventionally known inorganic particle-organic polymer composite, for example, epoxy resin, acrylic resin, polyimide resin, Organic polymers such as polyamide resin, polystyrene resin, polyethylene resin, polypropylene resin, polyvinyl alcohol resin, and polyvinyl butyl resin can be used, and a polymer dissolved in a liquid or solvent during mixing and kneading of soft agglomerated powder and organic polymer If it is a solution, there is no restriction | limiting in particular about the kind of organic polymer.

  Moreover, it is preferable that the inorganic particle-organic polymer composite paste of this embodiment is produced without performing chemical modification on the surface of the inorganic particles constituting the soft agglomerated powder. By comprising in this way, it is not necessary to use a chemical substance in the manufacturing process of an inorganic particle-organic polymer composite paste, and an environmentally conscious manufacturing process can be realized.

  The dispersion of the inorganic particles in the organic polymer is influenced by the magnitude of the shear stress of the organic polymer during kneading of the soft agglomerated powder and the organic polymer, in addition to the crushing strength of the soft agglomerated powder itself. That is, if the shear force of the organic polymer is larger than the cohesive force of the inorganic particles constituting the soft agglomerated powder, the soft agglomerated powder will be crushed. Generally, the shearing force (τ) of an organic polymer is represented by the following formula (2).

  τ = η × γ (2)

  In the above formula (2), τ represents the shearing force of the organic polymer, η represents the viscosity of the organic polymer, and γ represents the shear rate.

  As can be seen from the above formula (2), when the viscosity η of the organic polymer is high, the stress (shearing force) acting on the soft agglomerated powder (that is, the aggregate of inorganic particles) increases. For this reason, in the inorganic particle-organic polymer composite paste of the present embodiment, a condition in which the shear force of the organic polymer is stronger than that of the soft agglomerated powder is set, and the soft agglomerated powder and the organic polymer are mixed and kneaded. It is preferable that the soft agglomerated powder is dispersed in the polymer matrix. That is, if the shear stress of the organic polymer is stronger than the cohesive force between the inorganic particles, the inorganic particles are agglomerated and the inorganic particles are well dispersed in the organic polymer.

  More specifically, for example, it is preferable that the soft agglomerated powder and the organic polymer are mixed and the soft agglomerated powder is dispersed in the polymer matrix at a kneading speed of 50 to 5000 revolutions. For the kneading, a conventionally known mixing / kneading apparatus can be used. Specific examples include mixing and kneading apparatuses such as a kneader, a roll, a single-screw or multi-screw extruder, a mixer, a stirrer with a stirrer, and a rotation and revolution type stirrer.

  Moreover, in the inorganic particle-organic polymer composite paste of the present embodiment, the viscosity in kneading of the organic polymer to be used is preferably 0.1 to 100,000 Pa · s, and preferably 1 to 50,000 Pa · s. It is preferable. In this way, by making the organic polymer highly viscous, the shear force acting on the soft agglomerated powder can be effectively applied, and a composite paste in which the soft agglomerated powder is well dispersed in the polymer matrix is obtained. be able to.

  The surface state of the inorganic particles constituting the soft agglomerated powder dispersed in the organic polymer is preferably in a state that is not damaged as much as the particles constituting the inorganic raw material powder for producing the soft agglomerated powder. . That is, in the inorganic particle-organic polymer composite paste of this embodiment, the surface state of the inorganic particles is the same as that after the mill process even after the soft agglomerated powder is dispersed in the polymer matrix made of the organic polymer. It is preferable to maintain a state in which the particle surface is not damaged.

  Further, in the inorganic particle-organic polymer composite paste of the present embodiment, in order to favorably disperse the inorganic particles in the polymer matrix, the adsorption affinity between the organic polymer and the surface of the inorganic particles is also important. As shown in FIG. 2, the inorganic particles 10 exist in a polymer matrix composed of the organic polymer 12 and are in a state of being crosslinked and aggregated by the organic polymer 12. Therefore, if the adsorption affinity between the organic polymer 12 and the inorganic particles 10 is strong, particle movement, that is, flow becomes difficult, and mixing and kneading with a high powder content become difficult. Here, FIG. 2 is explanatory drawing which shows typically the structure of an inorganic particle-organic polymer composite paste.

  In the inorganic particle-organic polymer composite paste of the present embodiment, the fluidity is 10 to 90% with respect to the raw material powder composite paste composed of the inorganic raw material powder and the organic polymer for producing the soft agglomerated powder. It is preferable that the range is improved. By comprising in this way, the dispersibility of the inorganic particle in an organic polymer becomes favorable. The raw material powder composite paste described above is an inorganic powder obtained by crushing an inorganic raw material powder for producing a soft agglomerated powder without damaging the particle surface by a mill process, like the soft agglomerated powder of the present invention. The aggregated powder obtained by freeze-drying the slurry containing particles is not used, but a composite paste obtained by mixing and kneading the organic polymer with the inorganic raw material powder as the raw material.

[3] Method for producing inorganic particle-organic polymer composite paste:
Next, the manufacturing method of the inorganic particle-organic polymer composite paste of the present embodiment (hereinafter, sometimes referred to as “the manufacturing method of the present inorganic particle-organic polymer composite paste”) will be described.

  When producing the inorganic particle-organic polymer composite paste of the present embodiment, first, a slurry containing inorganic particles obtained by crushing inorganic raw material powder without damaging the particle surface by a mill process and crushing inorganic raw material powder. And the resulting slurry is lyophilized to obtain a soft agglomerated powder. In addition, about the method of producing this soft aggregation powder, it can carry out according to the method demonstrated in embodiment of the soft aggregation powder of this invention mentioned above.

  Next, an organic polymer for constituting a polymer matrix in the inorganic particle-organic polymer composite paste is prepared. About this organic polymer, the organic polymer currently used for preparation of a conventionally well-known inorganic particle-organic polymer composite body can be used suitably.

  Next, the prepared soft agglomerated powder and the organic polymer are mixed and kneaded to produce an inorganic particle-organic polymer composite paste. Any mixing / kneading device may be used as long as it can shear and knead the mixture of the soft agglomerated powder and the organic polymer. In addition, there is no restriction | limiting in particular about the presence or absence of the temperature adjustment means of heating or cooling. For example, apparatuses such as a kneader, a roll, a single-screw or multi-screw extruder, a mixer, a stirrer with a stirrer, and a rotation / revolution stirrer can be exemplified. The type of apparatus can be appropriately selected depending on the type and nature of the organic polymer used, the combination with the soft agglomerated powder, and the like. In addition, in the manufacturing method of this inorganic particle-organic polymer composite paste, it can knead on the conditions that the shear force of an organic polymer becomes stronger than the cohesion force of the inorganic particle which comprises soft aggregation powder. It is preferable.

  The affinity between the organic polymer and the inorganic particles can be defined by a measuring method such as a flow behavior by rheological measurement.

  Hereinafter, the method for producing the present inorganic particle-organic polymer composite paste will be described in more detail using specific examples. After producing the soft agglomerated powder, the organic polymer and the soft agglomerated powder are mixed so that the powder content is 1 to 75% by volume, preferably 1 to 70% by volume, and further kneaded to obtain a high powder. An inorganic particle-organic polymer composite paste is prepared. When a thermoplastic polymer is used as the organic polymer, it is preferable to knead by heating, and when a thermosetting polymer is used, a liquid organic polymer is used at a condition temperature before curing. Knead.

  As long as the effects of the present invention are not impaired, the soft agglomerated powder and the organic polymer may contain a plurality of types of powders (soft agglomerated powders) and organic polymers in order to improve the properties of the resulting inorganic particle-organic polymer composite paste. You may use together.

  In the method for producing the present inorganic particle-organic polymer composite paste, the inorganic particles are agglomerated by kneading or stirring the soft agglomerated powder and the organic polymer, and the particles are dispersed in the polymer matrix. That is, the soft agglomerated powder and the organic polymer are mixed, and the stirrer or kneader is preferably rotated at 50 to 5000 rotations, more preferably 100 to 3000 rotations, to disperse the inorganic particles into the polymer matrix. The kneading time is not particularly limited and is preferably performed until a composite paste having desired characteristics and dispersibility is obtained.

  Since the affinity between the organic polymer and the inorganic particles greatly affects the dispersibility and kneadability, the soft agglomerated powder is crushed once by a method that does not damage the particle surface, such as a wet jet mill, and freeze-dried. Use the same thing. Thereby, the adsorption affinity to the inorganic particle surface of an organic polymer can be reduced favorably. Compared with the composite paste of inorganic raw material powder and organic polymer, by using the soft agglomerated powder prepared using a wet jet mill, the fluidity of the resulting composite paste is improved in the range of 10 to 90%, Dispersibility in the organic polymer is improved.

  In this case, damage on the surface of the inorganic particles can be defined by observation with a transmission electron microscope such as TEM, confirmation of the hydration reaction on the surface of the inorganic particles by FTIR, confirmation of the composition by X-ray diffraction (XRD), etc. It is confirmed that the damage on the particle surface does not change (similar to the particle surface state) of the inorganic raw material powder after the mill process.

  The organic polymer to be used may be liquid or liquefied, but when its viscosity is low, the shear force becomes weaker than the cohesive force of the soft agglomerated powder and the dispersibility of the inorganic particles decreases. Thus, homogeneous kneading may not be performed. On the other hand, if the viscosity of the organic polymer is too high, the operability may be reduced. The viscosity of the organic polymer can be appropriately adjusted by temperature and solvent addition, and is not particularly limited. For example, the viscosity is preferably 0.1 to 100,000 Pa · s, and preferably 1 to 50,000 Pa · s. preferable.

  By the above production method, an inorganic particle-organic polymer composite paste in which inorganic particles are dispersed in an organic polymer with a high powder content can be produced without chemically modifying the surface of the inorganic particles.

  The inorganic particle-organic polymer composite paste obtained by such a production method contains 1 to 75% by volume of inorganic particles, can achieve a high powder content, and is excellent in fluidity. . For this reason, the movement of the inorganic particles in the organic polymer is good by compression molding using pressure, such as a dry press, a hot press, or a roll, that is, a conventionally known compression molding method. It is also applicable to sheet molding using inorganic particle-organic polymer composite paste, and the inorganic particles are dispersed even after being cured to form a composite material because of the favorable dispersibility of the inorganic particles in the composite paste. It can exist in the state.

  In the manufacturing method described above, the inorganic raw material powder is crushed by a milling process under specific conditions without chemically modifying the surface of the inorganic particles, and a soft agglomerated powder is produced by freeze drying. It becomes possible to knead with a high powder content using the shear stress during kneading of the organic polymer. That is, unlike the conventional manufacturing method, it is not necessary to use a chemical substance used for chemical modification, and an inorganic particle-organic polymer composite paste having a low environmental load and a high powder content can be easily manufactured. Furthermore, since the fluidity of the produced composite paste is high, the productivity and processability of the inorganic particle-organic polymer composite paste are improved, and the composite paste, the composite material composed of the composite paste, and the composite material are used. High performance of various members and various products can be expected. As described above, it is possible to exert a favorable influence not only in the industry related to the inorganic particle-organic polymer composite material and the member using the composite material, but also in various industries for manufacturing products using the composite material.

[4] Composite material (inorganic particle-organic polymer composite material):
Next, an embodiment of the composite material of the present invention will be described. The composite material of the present embodiment is an inorganic particle-organic polymer composite material composed of the inorganic particle-organic polymer composite paste described so far. The composite material of the present embodiment is composed of the inorganic particle-organic polymer composite paste of the present invention, which is excellent in productivity and processability, and each member using the composite material and improvement in performance of various products. Can be expected.

  The composite material (inorganic particle-organic polymer composite material) of the present embodiment can be produced by curing the inorganic particle-organic polymer composite paste of the present invention obtained as a paste. For example, it can be manufactured by being molded into a predetermined shape by compression molding using pressure such as a dry press, a hot press, or a roll, that is, a conventionally known compression molding method.

  EXAMPLES Next, although this invention is demonstrated concretely based on an Example, this invention is not limited at all by the following Example.

(I) Production and evaluation of soft aggregates:
Example 1
Aluminum oxide (alumina powder, Al ₂ O ₃ : average primary particle size 570 nm) was prepared as an inorganic raw material powder.

  The inorganic raw material powder was added to distilled water so as to have a powder content of 5% by volume to form a slurry, and the slurry was wet jet milled at 200 MPa. The slurry after milling was immediately frozen with liquid nitrogen and freeze-dried to obtain the soft agglomerated powder of Example 1 (hereinafter sometimes simply referred to as “aggregated powder”). In addition, the particle | grain surface state after a mill process was not damaged as shown in FIG. 1A (namely, it was a damage state comparable as an inorganic raw material powder).

The obtained soft agglomerated powder formed an agglomerated powder of about 50 to 200 μm. The crushing strength of the obtained soft agglomerated powder was measured with a micro pressure tester. The crushing strength was calculated as the tensile strength (σ _f ) from the measured value F of the load at which the aggregate collapses and the relational expression of the following formula (3).

σ _f = 2.8 F / πD ² (3)

  Here, in said formula (3), D shows the average particle diameter of an aggregate.

(Example 2)
A soft agglomerated powder was obtained in the same manner as in Example 1 except that zinc oxide (ZnO: average primary particle diameter 500 nm) was used as the inorganic raw material powder instead of aluminum oxide.

(Comparative Example 1)
As the milling process, a soft agglomerated powder was obtained in the same manner as in Example 1 except that the ball milling was performed for 24 hours. In Comparative Example 1, the particle surface state after the mill treatment was such that the surface of the inorganic particles was damaged as shown in FIG. 1B.

(Comparative Example 2)
As the milling process, a soft agglomerated powder was obtained in the same manner as in Example 2 except that the ball milling was performed for 24 hours.

Further, the agglomerated powder of Example 2, and Comparative Examples 1 and 2, in the same manner as in Example 1, a solution砕強degree was calculated as the tensile strength (sigma _f). Here, FIG. 3 is a graph showing the crushing strength of the soft agglomerated powder in Examples 1-2 and Comparative Examples 1-2. In addition, the result of the crushing intensity | strength of each inorganic raw material powder calculated | required from the same micro pressure test is also shown in FIG. 3 as reference data. In addition, the vertical axis | shaft in FIG. 3 shows crushing strength (MPa).

  As shown in FIG. 3, when attention is paid to the crushing strength, the agglomerated powder (Examples 1 and 2 and Comparative Examples 1 and 2) prepared through a crushing process is more crushing strength than the inorganic raw material powder. The agglomerated powder of Examples 1 and 2 (soft agglomerated powder), which was reduced by 4 to 15% and further treated by wet jet milling, had a lower crushing strength than the agglomerated powders of Comparative Examples 1 and 2 in which the surface produced by the ball mill was damaged. Met.

(II) Kneading of soft agglomerated powder and organic polymer (1):
Each of the aggregated powders of Examples 1 and 2 and Comparative Examples 1 and 2 is adjusted to a liquid epoxy (viscosity: 11 Pa · s) so that each has a powder content of 3% by volume, and dispersion after kneading The condition was observed. For the kneading, a stirrer using a stirrer was used. The following formula (4) was applied as the maximum stress (σ _max ) given by the rotor during kneading.

σ _max = {r (2πN / 60) 2η · t} / h (4)

  In the above formula (4), r represents the radius (m) of the stirrer (rotor), N represents the number of revolutions per minute (rpm), and η represents the viscosity (Pa · s). T represents the kneading time (hour), and h represents the height (m) of the stirrer (rotor).

In this example, the radius r of the stirrer (rotor) was 3.36 × 10 ⁻² m, and the height h of the stirrer (rotor) was 1.60 × 10 ⁻² m. When the rotational speed N was set to 300 rpm and the viscosity η of the liquid epoxy was 11 Pa · s, the stirring time required for crushing the soft agglomerated powder (aggregate of inorganic particles) was estimated. The stirring time required to disintegrate and disperse the inorganic particles in the organic polymer was about 20 minutes.

  Table 1 shows the stirring time required for crushing the untreated inorganic raw material powder, each of the aggregated powders of Examples 1-2 and Comparative Examples 1-2 at a rotational speed of 300 rpm.

  According to this stirring time, the liquid epoxy and the agglomerated powder of Example 1 were mixed (powder content: 3% by volume) under the condition of a rotation speed of 300 rpm, and the dispersed state after kneading was observed with a scanning electron microscope (SEM). did. Further, the liquid epoxy and the agglomerated powder of Example 1 were mixed (powder content: 3% by volume) under the condition of a rotation speed of 100 rpm, and the dispersion state after kneading was observed by SEM.

  Furthermore, liquid epoxy and the agglomerated powder of Comparative Example 1 were mixed (powder content: 3% by volume) under each condition of a rotational speed of 100 rpm and a rotational speed of 300 rpm, and the dispersion state after kneading was observed with an SEM.

  Here, FIG. 4A is a scanning electron microscope (SEM) photograph showing a dispersion state after kneading by mixing an inorganic raw material powder of aluminum oxide and a liquid epoxy under respective conditions of a rotational speed of 100 rpm and a rotational speed of 300 rpm. FIG. 4B is a scanning electron microscope (SEM) photograph showing the dispersion state after kneading by mixing the agglomerated powder of Comparative Example 1 and the liquid epoxy under respective conditions of a rotational speed of 100 rpm and a rotational speed of 300 rpm, and FIG. 2 is a scanning electron microscope (SEM) photograph showing a dispersion state after kneading by mixing the agglomerated powder of Example 1 and a liquid epoxy under conditions of a rotation speed of 100 rpm and a rotation speed of 300 rpm.

  Apparently, in the kneading of the soft agglomerated powder produced by the wet jet mill of Example 1 and the liquid epoxy, the agglomerated powder is crushed and dispersed at a rotational speed of 100 rpm or more. On the other hand, in the inorganic raw material powder and the agglomerated powder having a damaged surface produced by the ball mill of Comparative Example 1, the agglomerate remains at a rotational speed of 100 rpm, and the agglomerated powder is crushed and dispersed at 300 rpm. That is, the affinity between the liquid epoxy and the inorganic particle surface is different.

(III) Evaluation of fluidity of inorganic particle-organic polymer composite paste (1):
In the kneading (1) of the soft agglomerated powder and the organic polymer, the inorganic particles in the inorganic particle-organic polymer composite paste made of the Al ₂ O ₃ soft agglomerated powder and the liquid epoxy prepared by the wet jet mill of Example 1 are dispersed. It was confirmed that The agglomerated state in the composite paste can be distinguished by rheological behavior. Here, as an evaluation of the fluidity of the inorganic particle-organic polymer composite paste, the Al ₂ O ₃ soft agglomerated powder of Example 1 is added to a liquid epoxy (viscosity: 11 Pa · s) to a powder content of 30% by volume. Thus, the composite paste was obtained, and the flow curve after kneading of the obtained composite paste was measured.

In addition, the inorganic raw material powder (Al ₂ O ₃ ) and the agglomerated powder produced by the ball mill of Comparative Example 1 were also adjusted to a liquid epoxy (viscosity: 11 Pa · s) so as to have a powder content of 30% by volume. Thus, a composite paste was obtained, and the flow curve after kneading of the obtained composite paste was measured.

Here, FIG. 5 shows the relationship between the shear rate (s ⁻¹ ) and the shear stress (Pa) of the composite paste produced using the inorganic raw material powder, the agglomerated powder of Example 1, and the agglomerated powder of Comparative Example 1. It is a graph which shows (flow curve). In FIG. 5, the horizontal axis indicates the shear rate (s ⁻¹ ), and the vertical axis indicates the shear stress (Pa). In FIG. 5, Δ indicates the inorganic raw material powder, ○ indicates Comparative Example 1, and ● indicates Example 1.

  As shown in FIG. 5, the composite paste using the inorganic raw material powder and the agglomerated powder having a damaged particle surface produced from the ball mill of Comparative Example 1 clearly shows the going and returning behavior (in each direction of the arrow in FIG. 5). It is understood that thixotropy exists. Thixotropy occurs when the organic polymer is crosslinked between inorganic particles, that is, when the aggregated state collapses when shearing is applied to the aggregated state. On the other hand, the composite paste using the agglomerated powder produced by the wet jet mill of Example 1 has the same behavior of going and returning, and it can be seen that the relationship between the shear rate and the shear stress is proportional. This can be defined as Newtonian behavior, indicating that the inorganic particles are dispersed in the organic polymer and have high fluidity. By using the agglomerated powder of Example 1, it is possible to produce an inorganic particle-organic polymer composite paste with a good fluidity and a Newtonian flow curve.

(IV) Evaluation of the state of inorganic particles in the polymer matrix:
In the evaluation of the fluidity of the inorganic particle-organic polymer composite paste, the composite paste prepared by kneading Al ₂ O ₃ soft agglomerated powder and liquid epoxy prepared by the wet jet mill of Example 1 has Newtonian behavior and dispersibility. It showed high cohesion and low cohesion. This means that an inorganic particle-organic polymer composite paste having a high powder content can be produced as compared with the inorganic raw material powder and the aggregated powder of Comparative Example 1.

  Here, as an evaluation of the state of the inorganic particles in the polymer matrix, the inorganic raw material powder, the agglomerated powder of Example 1 and the agglomerated powder of Comparative Example 1 were added to the liquid epoxy so that the content of each powder was 60% by volume. Were added, and the state after stirring and kneading was confirmed.

  Here, FIG. 6A is a photograph showing an inorganic particle-organic polymer composite paste using an inorganic raw material powder of aluminum oxide, and FIG. 6B shows an inorganic particle-organic polymer composite paste using the aggregated powder of Comparative Example 1. 6C is a photograph showing an inorganic particle-organic polymer composite paste using the aggregated powder of Example 1. FIG.

  As shown in FIG. 6A, when the inorganic raw material powder was used, the kneaded part and the part where the inorganic powder remained existed, and homogeneous kneading could not be performed. Further, as shown in FIG. 6B, when the agglomerated powder having a damaged surface produced by the ball mill of Comparative Example 1 was used, inorganic particle lumps were generated, and homogeneous kneading could not be performed.

  On the other hand, as shown in FIG. 6C, when soft agglomerated powder made of inorganic particles having no surface damage produced by a wet jet mill was used, it was observed that homogeneous kneading could be achieved. The composite paste using the aggregated powder of Example 1 was cured to produce a composite material. Here, FIG. 7 is a scanning electron microscope (SEM) photograph of the composite material obtained by curing the composite paste using the aggregated powder of Example 1. As shown in FIG. 7, it can be seen that the inorganic particles are present as primary particles in the polymer matrix. As described above, by using the soft agglomerated powder of the present invention obtained by freeze-drying the slurry containing inorganic particles crushed in a state where the particle surface is not damaged, uniform kneading is achieved in a high powder content. In addition, an inorganic particle-organic polymer composite material having an internal structure composed of inorganic particles uniformly dispersed in a polymer matrix can be produced.

(V) Kneading of soft agglomerated powder and organic polymer (2):
(Examples 3 and 4)
Using zinc oxide (ZnO) as the inorganic raw material powder, soft agglomerated powders (Examples 3 and 4) were prepared using a wet jet mill, and the above-mentioned “kneading of soft agglomerated powder and organic polymer (1)” In the same manner, kneading with liquid epoxy was performed to prepare an inorganic particle-organic polymer composite paste.

  In Example 3, an inorganic raw material powder (zinc oxide) and water were mixed to obtain a slurry so that the powder content was 5% by volume, and the obtained slurry was freeze-dried after wet jet mill treatment. A soft agglomerated powder was produced. Also in Example 3, the surface of the inorganic particles after the wet jet mill treatment was not damaged.

  Moreover, in Example 4, inorganic raw material powder (zinc oxide), water, and 0.15 mass% polyacrylic acid ammonium salt (dispersant) were added so that it might become 20 volume% powder content. A slurry was obtained, and the resulting slurry was wet-jet milled and then lyophilized to produce a soft agglomerated powder. Also in Example 4, the surface of the inorganic particles after the wet jet mill treatment was not damaged.

  The agglomerated powder of Example 3 and the liquid epoxy were mixed so that the content ratio of the agglomerated powder was 3% by volume, and a stirrer using a stirrer was rotated under each condition of 100 rpm and 300 rpm to obtain a composite paste. Produced.

  In addition, the inorganic raw material powder used in the production of the aggregated powder of Example 3 was kneaded in the same manner as the aggregated powder of Example 3 without crushing, to prepare a composite paste for comparison. .

  Each composite paste using the soft agglomerated powders of Examples 3 and 4 and the above-described comparative composite paste (using inorganic raw material powder) were cured to obtain a composite material. The dispersion state of the particles was observed with a scanning electron microscope (SEM). Here, FIG. 8A is a scanning electron microscope (SEM) photograph showing a dispersion state after kneading by mixing an inorganic raw material powder of zinc oxide and a liquid epoxy under respective conditions of a rotational speed of 100 rpm and a rotational speed of 300 rpm. FIG. 8B is a scanning electron microscope (SEM) photograph showing a dispersion state after kneading by mixing the agglomerated powder of Example 3 and the liquid epoxy under respective conditions of a rotation speed of 100 rpm and a rotation speed of 300 rpm.

  Particle dispersion of the composite material produced from the inorganic raw material powder for comparison was not achieved at 100 rpm, but was dispersed in the polymer in the state of primary particles at 300 rpm. On the other hand, the inorganic powder in the composite material obtained by kneading the soft agglomerated powder and liquid epoxy of Example 3 is pulverized at a rotational speed of 100 rpm and is in a dispersed state. That is, the soft agglomerated powder of the present invention (Example 3) can be dispersed in the polymer at a low kneading speed. In addition, it was confirmed that Example 4 produced using a dispersant can be dispersed in the organic polymer at a low kneading rate as in Example 3.

(VI) Evaluation of fluidity of inorganic particle-organic polymer composite paste (2):
The soft agglomerated powder of Example 3 was kneaded with liquid epoxy so as to have a powder content of 20% by volume with a rotation / revolution type stirrer at a rotation speed of 2000 rpm to prepare a composite paste having a high powder content. . The flow curve after kneading of the obtained composite paste was measured by the same method as in “Evaluation of fluidity of inorganic particle-organic polymer composite paste (1)”.

In addition, for the agglomerated powder of Example 4 and the inorganic raw material powder (not pulverized) used for the production of the agglomerated powder of Example 3, composite paste (powder content 20% by volume) was obtained in the same manner. And the flow curve after kneading of the obtained composite paste was measured. Here, FIG. 9 shows the relationship between the shear rate (s ⁻¹ ) and shear stress (Pa) of the composite paste produced using the inorganic raw material powder, the agglomerated powder of Example 3, and the agglomerated powder of Example 4. It is a graph which shows. In FIG. 9, ◯ indicates inorganic raw material powder, Δ indicates Example 3, and black triangle indicates Example 4.

  The flow curve of the composite paste using the agglomerated powder prepared by the wet jet mill of Example 3 was Newtonian, and the flow curve of the composite paste prepared using the inorganic raw material powder as it was showed thixotropy. In other words, the soft agglomerated powder of the present invention produced by wet-jet milling an inorganic raw material powder and then freeze-drying is easily crushed in an organic polymer (liquid epoxy), has a low agglomeration property, and flows. It was confirmed that the property is high. Moreover, about Example 4 using a dispersing agent, the shear stress of the composite paste obtained became low, and it was confirmed that fluidity | liquidity increases 50% rather than the case where a dispersing agent is not added.

  The soft agglomerated powder of the present invention can uniformly disperse inorganic particles in a polymer matrix made of an organic polymer, and can be used for producing a highly fluid and easily moldable inorganic particle-organic polymer composite paste. it can. The inorganic particles can be pulverized and dispersed in the polymer matrix in the form of primary particles. In addition, since inorganic particles can be uniformly dispersed in the organic polymer without chemically modifying the surface of the inorganic particles, for example, no chemical substance is used in the manufacturing process of the inorganic particle-organic polymer composite paste or composite material. In any case, an environmentally harmonious manufacturing process can be realized.

  In addition, the soft agglomerated powder of the present invention can increase the powder content of inorganic particles to 1 to 75% by volume, and its fluidity is compared with a composite paste prepared by kneading raw material powder and polymer as they are. 10 to 90%, the problem of reciprocal properties of high powder content and moldability is solved, and production of inorganic particles-organic polymer composite paste with low cost and high properties can be expected.

  In addition, the inorganic particle-organic polymer composite paste of the present invention has a low adsorption affinity and high fluidity between the inorganic particles and the organic polymer, so that the easily-formable inorganic particles in which the inorganic particles are well dispersed in the polymer matrix. -It can be an organic polymer composite paste. For this reason, it can utilize suitably for compression molding using pressure, such as a dry press machine, a hot press machine, and a roll machine, sheet molding.

It is a transmission electron microscope (TEM) photograph of the particle | grain surface after a wet jet mill. It is a transmission electron microscope (TEM) photograph of the particle | grain surface after a ball mill. It is explanatory drawing which shows typically the structure of an inorganic particle-organic polymer composite paste. It is a graph which shows the crushing intensity | strength of the aggregated powder in Examples 1-2 and Comparative Examples 1-2. It is a scanning electron microscope (SEM) photograph which shows the dispersion | distribution state after knead | mixing the inorganic raw material powder of aluminum oxide, and liquid epoxy on each condition of rotational speed 100rpm and rotational speed 300rpm. It is a scanning electron microscope (SEM) photograph which shows the dispersion | distribution state after kneading | mixing the aggregated powder and liquid epoxy of the comparative example 1 on each condition of rotational speed 100rpm and rotational speed 300rpm. It is a scanning electron microscope (SEM) photograph which shows the dispersion | distribution state after kneading | mixing the aggregated powder and liquid epoxy of Example 1 on each condition of rotational speed 100rpm and rotational speed 300rpm. It is a graph which shows the relationship between the shear rate (s ^<-1> ) and the shear stress (Pa) of the composite paste produced using the inorganic raw material powder, the aggregated powder of Example 1, and the aggregated powder of Comparative Example 1. It is a photograph which shows the inorganic particle-organic polymer composite paste using the inorganic raw material powder of aluminum oxide. 4 is a photograph showing an inorganic particle-organic polymer composite paste using the agglomerated powder of Comparative Example 1. 2 is a photograph showing an inorganic particle-organic polymer composite paste using the agglomerated powder of Example 1. FIG. It is the scanning electron microscope (SEM) photograph of the composite material which hardened the composite paste using the aggregated powder of Example 1. FIG. It is a scanning electron microscope (SEM) photograph which shows the dispersion | distribution state after kneading | mixing the inorganic raw material powder of zinc oxide, and liquid epoxy on each condition of rotational speed 100rpm and rotational speed 300rpm. It is a scanning electron microscope (SEM) photograph which shows the dispersion | distribution state after kneading | mixing the aggregated powder and liquid epoxy of Example 3 on each condition of rotational speed 100rpm and rotational speed 300rpm. It is a graph which shows the relationship between the shear rate (s < ^-1 >) and shear stress (Pa) of the composite paste produced using the inorganic raw material powder, the aggregated powder of Example 3, and the aggregated powder of Example 4.

Explanation of symbols

10: inorganic particles, 12: organic polymer.

Claims (13)

  A soft agglomerated powder obtained by freeze-drying a slurry containing inorganic particles obtained by pulverizing an inorganic raw material powder by a mill process without damaging the particle surface.   The soft agglomerated powder according to claim 1, wherein the crushing strength is reduced in a range of 1 to 50% with respect to the crushing strength of the inorganic raw material powder, and the crushing strength is 1 to 30 MPa.   The soft agglomeration according to claim 1 or 2, wherein the slurry is obtained by pulverizing the inorganic raw material powder by the mill process using a wet jet mill so that a collision pressure between the slurries becomes 50 to 300 MPa. Powder.   The soft aggregation powder as described in any one of Claims 1-3 obtained by freeze-drying the said slurry crushed by adding a dispersing agent to the said inorganic raw material powder. Containing the soft agglomerated powder according to any one of claims 1 to 4 and an organic polymer,
An inorganic particle-organic polymer composite paste in which the content of the soft agglomerated powder is 1 to 75% by volume.   The inorganic particle-organic polymer composite paste according to claim 5, wherein the inorganic particle-organic polymer composite paste is produced without chemically modifying the surface of the inorganic particles constituting the soft agglomerated powder.   The condition that the shear force of the organic polymer is stronger than the cohesive force of the soft agglomerated powder is set, the soft agglomerated powder and the organic polymer are mixed and kneaded, and the soft agglomerated powder is dispersed in the polymer matrix. The inorganic particle-organic polymer composite paste according to claim 5 or 6.   The inorganic particle-organic polymer composite paste according to claim 7, wherein the soft agglomerated powder and the organic polymer are mixed and the soft agglomerated powder is dispersed in the polymer matrix at a kneading speed of 50 to 5000 revolutions.   The fluidity of the raw material powder composite paste composed of the inorganic raw material powder and the organic polymer for producing the soft agglomerated powder is improved in the range of 10 to 90%. The inorganic particle-organic polymer composite paste according to one item.   The inorganic particle-organic polymer composite paste according to claim 8 or 9, wherein the organic polymer has a viscosity of 0.1 to 100,000 Pa · s in kneading.   The inorganic particle-organic polymer composite paste according to any one of claims 5 to 10, wherein inorganic particles constituting the soft agglomerated powder dispersed in the organic polymer are present in the polymer matrix in a state of primary particles.   The surface state of the inorganic particles constituting the soft agglomerated powder dispersed in the organic polymer is in a state that is not damaged as much as particles constituting the inorganic raw material powder for producing the soft agglomerated powder. The inorganic particle-organic polymer composite paste according to any one of 5 to 11.   A composite material comprising the inorganic particle-organic polymer composite paste according to any one of claims 5 to 12.