JP2006151709A - Ceramic formed body and method of producing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of producing an inorganic material formed body by which the formed body having small defects, high mechanical strength and excellent quality is produced under a mild condition where firing at a high temperature such as ≤500°C is needless without adding a large quantity of an organic material while securing excellent formability and shape holding property after forming. <P>SOLUTION: In the method of producing the inorganic material formed body, the inorganic material formed body is obtained by using a stimulation-responsive inorganic material particle constituted so that an organic atomic group is incorporated in an inorganic material particle and a modifying atomic group having a functional group (stimulation-responsive functional group) causing bonding reaction with other functional groups by responding to external simulation is chemically modified as a raw material, forming a mixture containing the stimulation-responsive inorganic material particle into a prescribed shape to obtain a green body precursor and giving the external stimulation to the green body precursor to form a cross-linking atomic group to bond the inorganic material particles with each other by using the bonding reaction between the stimulation-responsive functional group and other functional groups. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an inorganic material molded body composed of an inorganic material such as ceramics or metal, and a method for producing the same. Specifically, it is suitably used in a method for manufacturing an inorganic material molded body capable of obtaining a molded body having high mechanical strength under mild conditions that do not require firing at a high temperature of 500 ° C. or higher, and the manufacturing method thereof. The present invention relates to a stimulus-responsive inorganic material particle and a method for producing the same.

  Inorganic materials such as ceramics and metals are superior in mechanical strength and durability compared to organic materials such as plastics, and are therefore used in various applications such as structural materials and electrical / electronic materials. And these inorganic materials are generally used as a molded object (inorganic material molded object) shape | molded in the shape suitable for each use.

  As a method for producing such an inorganic material molded body, for example, an aggregate particle (ceramic powder, etc.), a dispersion medium (water, etc.), an organic binder, etc. are mixed and kneaded to obtain a clay, and the clay is extruded. A method for producing an inorganic material molded body in which a ceramic sintered body is obtained by molding, drying, and firing by a method such as molding is disclosed (high-temperature sintering method: see, for example, Patent Document 1).

  Also, aggregate particles (ceramic powder, etc.), dispersion medium (water, etc.), organic binder, etc. are mixed to obtain a slurry (slip), and the slurry is poured into a water-absorbing mold composed of a porous body. A manufacturing method for obtaining an inorganic material molded body by drying and solidifying and then degreasing is disclosed (casting molding method (slip casting method): see Non-Patent Document 1, for example).

  Furthermore, aggregate particles (ceramic powder, etc.), dispersion medium (water, etc.), gelling agent (monomer, prepolymer, etc.), etc. are mixed to obtain a slurry, and the slurry is poured into a mold and heated. A manufacturing method is disclosed in which a gelling agent is gelled by addition of a polymerization initiator or the like to solidify a slurry, and then degreased to obtain an inorganic material molded body (gel casting method: see, for example, Patent Document 2) ).

Japanese Patent No. 3227039 JP 2002-179468 A Edited by the Ceramic Society of Japan, Ceramics Engineering Handbook, 2nd edition, Gihodo Publishing, 2002, p. 176-178

  The high-temperature sintering method has an advantage that a high-strength inorganic material molded body can be obtained because the diffusion of the substance is caused by firing and a bond is formed between the aggregate particles. However, since firing at a high temperature of 500 to 2000 ° C. is necessary, in addition to requiring a large amount of energy for production, there is a restriction on equipment that special high-temperature equipment is required. Further, in order to ensure good moldability and shape retention after molding, it is necessary to add a large amount of organic binder such as 10 to 15 parts by mass with respect to 100 parts by mass of the aggregate particles. Due to this large amount of organic binder, during firing, i) the space occupied by the organic binder becomes voids (defects), and the mechanical strength of the sintered body decreases, ii) thermal stress when the organic binder burns Acts, and cracks (defects) are generated in the sintered body. Iii) The firing time is extended by the amount of burning of the organic binder. Iv) Carbon dioxide and harmful gases are generated by the burning of the organic binder. Various problems such as causing air pollution and air pollution remain, and they are still not fully satisfactory.

  The casting molding method and the gel casting method do not necessarily require firing at a high temperature. Therefore, the energy consumption during production can be reduced compared to the high-temperature sintering method, and there are few advantages on equipment. is there. However, these methods also require the addition of a large amount of an organic binder or gelling agent in order to ensure good moldability and shape retention after molding. That is, these methods are not different from the high-temperature sintering method in that a large amount of organic matter is contained in the molded body, and the same problems as the high-temperature sintering method remain due to the organic matter. It still left room for improvement.

  As described above, at present, it is possible to ensure good moldability and shape retention after molding without adding a large amount of organic matter under mild conditions that do not require firing at a high temperature of 500 ° C. or higher. In addition, a manufacturing method of an inorganic material molded body capable of obtaining a molded article of good quality with few defects and high mechanical strength has not yet been disclosed, and the creation of such a manufacturing method is eagerly desired by the industry. ing.

  The present invention has been made to solve the above-described problems of the prior art, and is good without adding a large amount of organic matter under mild conditions that do not require firing at a high temperature of 500 ° C. or higher. In addition to ensuring good moldability and shape retention after molding, a method for producing an inorganic material molded body capable of obtaining a molded article of good quality with few defects and high mechanical strength is provided.

  In developing the method for producing an inorganic material molded body of the present invention, the present inventors can form a strong bond between aggregate particles unless the conventional method is fired at a high temperature of 500 ° C. or higher. First, the reason why good moldability and shape retention after molding could not be secured unless a large amount of organic substance was added was examined.

  As a result, in the conventional method, i) it is difficult to cause diffusion of the substance and form a bond between aggregate particles in a temperature range not reaching 500 ° C., ii) organic binders, gelling agents, etc. It is adsorbed on the surface of the aggregate particles or is only loosely bonded, and the binding force for linking the aggregate particles is not sufficient. Iii) Inorganic material particles that become aggregate particles, and an organic binder or gelling agent Due to low affinity with organic materials such as these, phase separation and partial aggregation, the organic binder and gelling agent are not functioning effectively, etc. It has been found that a strong bond cannot be formed between inorganic material particles without firing, and good moldability and shape retention after molding cannot be secured unless a large amount of organic substance is added.

  Therefore, as a result of the earnest study by the present inventors, the inorganic material particles to be aggregate particles are bonded to each other by a strong bond called a covalent bond via a bridging atomic group containing an organic atomic group, The present invention was completed by conceiving that good moldability and shape retention after molding can be ensured without adding a large amount of organic matter under mild conditions that do not require firing at a high temperature of 500 ° C. or higher. . Specifically, the present invention provides the following inorganic material molded body and manufacturing method thereof, stimuli-responsive inorganic material particles suitably used in the manufacturing method, manufacturing method thereof, and manufacturing method of an inorganic material sintered body To do.

[1] (A): An inorganic material particle to be an aggregate particle, and (B): a bridging atomic group containing an organic atomic group as constituent elements, and (B): the bridging atomic group is the above (A ): An inorganic material molded body having a structure in which the inorganic material particles are bonded to each other by a covalent bond, and each of the (A): inorganic material particles is bonded to each other by the (B): bridging atomic group.

[2] The group (B): the bridging atomic group is a phenylhydrazo group (—C ₆ H ₄ —NHNH—), an amide group (—NHCO—), and an imide group (—N (CO—) ₂ ). The inorganic material molded body according to the above [1], which contains at least one functional group selected from the group consisting of:

[3] Oxide ceramics, non-oxide ceramics, and inorganic material particles made of at least one inorganic material selected from the group of metals and a bridging atomic group containing an organic atomic group as constituent elements, the bridging A method for producing an inorganic material molded body having a structure in which atomic groups are bonded to the inorganic material particles by a covalent bond, and each of the inorganic material particles is bonded to each other by the bridging atomic group. A modified atomic group containing a functional group (stimulus-responsive functional group) containing an organic atomic group and causing a binding reaction with another functional group in response to an external stimulus is chemically modified in the inorganic material particle. The stimulus-responsive inorganic material particles are used as raw materials, and the mixture containing the stimulus-responsive inorganic material particles is molded into a desired shape to obtain a molded body precursor. Second step: By applying a partial stimulus and utilizing the binding reaction between the stimulus-responsive functional group and the other functional group to form the bridging atomic group that bonds the inorganic material particles to each other, The manufacturing method of an inorganic material molded object which obtains a material molded object.

[4] In addition to the stimulus-responsive inorganic material particle, the inorganic material particle includes an organic atomic group and can form a bond with the stimulus-responsive functional group (binding functional group). The modified atomic group is bonded to the modified atomic group by using a binding reaction between the stimuli-responsive functional group and the binding functional group, using as a raw material a binding inorganic material particle that has been chemically modified. The method according to [3], wherein the bridging atomic groups for bonding the inorganic material particles to each other are formed.

[5] Using, as a raw material, a polyfunctional organic compound having two or more reactive functional groups (binding functional groups) capable of forming a bond with the stimulus-responsive functional group in addition to the stimulus-responsive inorganic material particles And using the bonding reaction between the stimuli-responsive functional group and the binding functional group to bond the modified atomic groups to each other through the polyfunctional organic compound, and the inorganic material particles are mutually bonded. The production method according to [3], wherein the bridging atomic group to be bonded is formed.

[6] By light irradiation, a binding reaction between the phenyl azide group (—C ₆ H ₄ —N ₃ ) as the stimulus-responsive functional group and the amino group (—NH ₂ ) as the binding functional group is performed. The production method according to [4] or [5], wherein the process proceeds to form a phenylhydrazo bond (—C ₆ H ₄ —NHNH—).

[7] By the microwave irradiation, the binding reaction between the amino group (—NH ₂ ) as the stimulus responsive functional group and the carboxyl group (—COOH) as the stimulus responsive functional group is allowed to proceed. The production method according to [4] or [5], wherein a bond (—N (CO—) ₂ ) is formed.

[8] Utilizing a bonding reaction between the amino group (—NH ₂ ) as the stimulus-responsive functional group and the carboxyl group (—COOH) as the stimulus-responsive functional group by heating at 300 ° C. or lower. The production method according to [4] or [5], wherein an amide bond (—NHCO—) is formed.

[9] An inorganic material sintered body obtained by the method according to any one of [3] to [8] to obtain an inorganic material molded body, and firing the inorganic material molded body to obtain an inorganic material sintered body. Production method.

[10] (C): inorganic material particles made of an inorganic material, and (D): a functional group containing an organic atomic group and causing a binding reaction with another functional group in response to an external stimulus (stimulus responsiveness) And (C): a stimulus-responsive inorganic material having a structure in which the modified atomic group is covalently bonded to the inorganic material particle. Material particles.

[11] The stimulus-responsive inorganic material according to [10], wherein (D): the modified atomic group has a phenyl azide group (—C ₆ H ₄ —N ₃ ) as the stimulus-responsive functional group. particle.

[12] A modified atomic group containing an inorganic material particle made of an inorganic material and an organic atomic group, and having a functional group (stimulus-responsive functional group) that causes a binding reaction with another functional group in response to an external stimulus And a method for producing stimuli-responsive inorganic material particles having a structure in which the modifying atomic group is covalently bonded to the inorganic material particles, wherein the inorganic material particles are oxidized. A material composed of at least one inorganic material selected from the group consisting of physical ceramics, non-oxide ceramics, and metals is used to chemically modify the modified atomic group having the stimuli-responsive functional group on the inorganic material particles. A method for producing stimuli-responsive inorganic material particles to be modified.

[13] First step: A silanol residue is produced by causing a silane coupling agent to act on the inorganic material particles and causing a condensation reaction between the inorganic material particles and the silane coupling agent. A silanol-bonded inorganic material particle having a structure bonded to the inorganic material particle by a covalent bond is obtained, and the second step: the organic compound having the stimulus-responsive sensitive group acts on the silanol-bonded inorganic material particle Wherein the modified atomic group is formed by causing a bond forming reaction between the silanol-bonded inorganic material particles and the organic compound, thereby obtaining the stimulus-responsive inorganic material particles. Production method.

[14] The production method according to [12] or [13], wherein the organic compound is a compound in which the stimulus-responsive functional group is a phenyl azide group (—C ₆ H ₄ —N ₃ ).

  The method for producing a molded body of an inorganic material according to the present invention has good moldability and shape retention after molding without adding a large amount of organic matter under mild conditions that do not require firing at a high temperature of 500 ° C. or higher. In addition to being able to be ensured, there is an advantageous effect compared with the conventional manufacturing method that a molded article of good quality with few defects and high mechanical strength can be obtained.

  BEST MODE FOR CARRYING OUT THE INVENTION The best mode for carrying out the inorganic material molded body and the method for producing the same of the present invention will be specifically described below. However, the present invention broadly encompasses an inorganic material molded body based on the idea that each of the inorganic material particles to be aggregate particles is bonded to each other by a bridging atomic group containing an organic atomic group, and a method for producing the same, The present invention should not be construed as being limited to the embodiments described below.

  The method for producing an inorganic material molded body according to the present invention includes inorganic material particles to be aggregate particles and a bridging atomic group containing an organic atomic group as constituent elements, and the bridging atomic group is covalently bonded to the inorganic material particle. This is a production method for obtaining an inorganic material molded body having a structure in which each of inorganic material particles is bonded to each other by a bridging atomic group.

[1] First Step In the first step of the production method of the present invention, a stimulus-responsive inorganic material particle is used as a raw material, and a mixture containing the stimulus-responsive inorganic material particle is molded into a desired shape to obtain a molded body precursor. This is a molded body precursor manufacturing process.

  Aggregate particles are particles that are the main constituents of a molded body. When an inorganic material molded body is manufactured, inorganic material particles made of an inorganic material are used. In the production method of the present invention, it is necessary to use stimuli-responsive inorganic material particles as a raw material.

  The “stimulus-responsive inorganic material particle” referred to in the present specification is an inorganic material particle in which a modified atomic group containing an organic atomic group and having a stimulus-responsive functional group is chemically modified.

  The “modified atomic group” needs to contain an organic atomic group and have a functional group (stimulus-responsive functional group) that causes a binding reaction with another functional group in response to an external stimulus. “Organic atomic group” means an atomic group containing a carbon atom as a constituent atom, and the other structure is not particularly limited. By appropriately selecting the structure of the modified atomic group including the organic atomic group, it is possible to form a strong bond between inorganic material particles easily and with high efficiency even under high temperature conditions of 500 to 2000 ° C. Is preferable in that.

  “Stimulus-responsive functional group” means a functional group that causes a binding reaction with another functional group in response to an external stimulus. By utilizing the bonding reaction between the stimulus-responsive functional group and another functional group, it is possible to form a bridging atomic group that binds each of the inorganic material particles to each other.

  “External stimulus” means physical or chemical stimulus supplied from the external environment, such as thermal stimulus (heating), light stimulus (light irradiation), electrical stimulus (voltage application), magnetic stimulus, etc. Examples include physical stimulation, chemical stimulation such as pH change (addition of acid / alkali) and moisture change. Since the manufacturing method of the present invention is intended to obtain a molded article having high mechanical strength under mild conditions that do not require firing at a high temperature of 500 ° C. or higher, external stimuli that meet such conditions It is desirable to cause a binding reaction with other functional groups. Examples of such external stimuli include light irradiation, microwave irradiation, ultrasonic irradiation, heating at low temperature, and room temperature plasma.

As the stimulus-responsive functional group, a phenylazide group (—C ₆ H ₄ —N ₃ ) that forms a hydrazo bond (—NHNH—) by causing a binding reaction with an amino group (—NH ₂ ) by light irradiation. ) And the like. The stimulus-responsive functional groups include those in which a binding reaction is induced by the action of one functional group, such as a phenyl azide group, and those in which a binding reaction is caused by the interaction of two functional groups. It is. For example, when a combination of an amino group (—NH ₂ ) and a carboxyl group (—COOH) is used as a stimulus-responsive functional group, a binding reaction is induced between the two functional groups by microwave irradiation, and an imide bond (—N (CO−) ₂ ) can be formed, and an amide bond (—NHCO—) can be formed by heating at 300 ° C. or lower.

  Here, a method for producing stimulus-responsive inorganic material particles will be described. The stimulus-responsive inorganic material particles are produced by chemically modifying a modified atomic group having a stimulus-responsive functional group with respect to the inorganic material particles. Accordingly, the “inorganic material particles” are preferably made of an inorganic material having a binding site (hydroxyl group or the like) capable of forming a covalent bond with a modified atomic group. For example, oxide ceramics having a surface hydroxyl group The particle | grains which consist of can be used suitably. Also, particles made of non-oxide ceramics or metals can be used as “inorganic material particles” because oxide ceramics are inevitably formed on the surface by air oxidation (surface oxide film). That is, in the production method of the present invention, it is preferable to use inorganic material particles made of at least one inorganic material selected from the group of oxide ceramics, non-oxide ceramics, and metals.

  Examples of oxide ceramics include metal oxides such as barrier, ceria, zinc oxide, germanium oxide, indium oxide, tin oxide, and antimony oxide, as well as general-purpose ceramics such as silica, alumina, zirconia, and titania. These oxide ceramics have a surface hydroxyl group to be a binding site, and are preferable in that chemical modification of the modifying atomic group is easy. Examples of non-oxide ceramics include silicon carbide and silicon nitride. Examples of metals include silicon, aluminum, zirconium, titanium, barium, cerium, zinc, germanium, indium, tin, and antimony.

  The average particle diameter of the “inorganic material particles” is preferably in the range of 1 nm to 50 μm, and more preferably in the range of 10 to 500 nm. If it is less than the above range, the specific surface area of the inorganic material particles becomes excessive, and the proportion of the modified atomic group per unit mass of the inorganic material particles may be too large. In such a case, there is a possibility that an inorganic material molded body having a small organic content, which is the object of the present invention, may not be obtained, which is not preferable. On the other hand, if the above range is exceeded, the activity of the surface of the inorganic material particles may be reduced and it may be difficult to form a bond with the modifying atomic group, and when the slurry is made, the inorganic material particles are likely to settle, Handling may be difficult. In the present specification, the term “average particle size” refers to an X-ray transmission type particle size distribution measuring apparatus (for example, trade name: Cedi, which uses the Stokes liquid phase precipitation method as a measurement principle and performs detection by the X-ray transmission method. It means the value of 50% particle diameter measured by Graph 5000-02 type, manufactured by Shimadzu Corporation.

  The method for chemically modifying the modifying atomic group is not particularly limited, and a conventionally known chemical modification method can be used. Examples thereof include a method of fixing organic molecules with a coupling agent, a method of fixing organic molecules by an autoclave method, a method using surface modification by corona discharge, a method using surface modification by ozone, and the like. Among them, it is preferable to use a method of fixing organic molecules with a coupling agent because it is possible to easily form a strong bond.

  As coupling agents, for example, silane coupling agents, titanate coupling agents, aluminum coupling agents, chromium coupling agents and the like are known, but a stable water / methanol solution can be easily obtained. In this respect, it is preferable to use a silane coupling agent.

  Examples of the chemical modification method using a silane coupling agent include the following methods.

  First, a silanol residue acts on the inorganic material particles by causing a silane coupling agent to act on the inorganic material particles and causing a condensation reaction between the inorganic material particles and the silane coupling agent. Silanol-bonded inorganic material particles having a structure bonded by covalent bonds are obtained (first step).

（但し、Ｈｙ₁，Ｈｙ₂，Ｈｙ₃：加水分解性官能基、Ａ：有機原子団、Ｒｅ₁：反応性官能基、Ｐｉ：無機材料粒子） For example, as shown in the following general formula (1), a silane coupling agent (II) is allowed to act on the inorganic material particles (I), and the surface hydroxyl groups (OH) of the inorganic material particles (I) and the silane system By causing a condensation reaction with the hydrolyzable functional groups (Hy ₁ , Hy ₂ , Hy ₃ ) of the coupling agent (II), silanol residues are bonded to the inorganic material particles by covalent bonds. Silanol-bound inorganic material particles (III) having the above structure are obtained.

(However, Hy ₁ , Hy ₂ , Hy ₃ : Hydrolyzable functional group, A: Organic atomic group, Re ₁ : Reactive functional group, Pi: Inorganic material particles)

Examples of the hydrolyzable functional group (Hy ₁ , Hy ₂ , Hy ₃ ) include an alkoxy group (RO—: R is an alkyl group). Each functional group may be the same functional group or a different functional group. In the case of an alkoxy group, it is hydrolyzed by the presence of water to produce a silanol group (—SiO—), and the silanol group is adsorbed on the surface hydroxyl group of the inorganic material particles by a hydrogen bond. By heating this at a high temperature, silanol groups and surface hydroxyl groups undergo dehydration condensation, and silanol residues are bonded to the inorganic material particles by covalent bonds.

  Next, the modified atomic group is formed by causing an organic compound having a stimulus-responsive sensitive group to act on the silanol-bonded inorganic material particles and causing a bond-forming reaction between the silanol-bonded inorganic material particles and the organic compound. Form stimuli-responsive inorganic material particles (second step).

（但し、Ａ，Ｅ：有機原子団、Ｒｅ₁，Ｒｅ₂：反応性官能基、Ｐｉ：無機材料粒子、Ｓｔ：刺激応答性感応基、Ｇ：結合又は原子団） For example, as shown in the following general formula (2), the silanol-binding inorganic material particles (III) are allowed to act on the silanol-binding inorganic material particles (III) with an organic compound (IV) having a stimulus-responsive sensitive group St. The reactive functional group Re ₁ of the organic compound (IV) and the reactive functional group Re ₂ of the organic compound (IV) cause a bond forming reaction to form a modified atomic group, thereby stimulating-responsive inorganic material particles (V) Get.

(However, A, E: organic atomic group, Re _1, Re _2: reactive functional groups, Pi: inorganic material particles, St: stimulus-responsive sensitive group, G: bonded or atomic group)

Examples of the reactive functional group Re ₁ and the reactive functional group Re ₂ include a combination of an amino group and a carboxyl group. When such a combination of functional groups is used, an amide bond can be formed by heating at 300 ° C. or lower, and a modified atomic group can be formed.

  In addition to the above method, a silane coupling agent having a stimulus-responsive sensitive group St is allowed to act on the inorganic material particles, and the surface hydroxyl groups of the inorganic material particles and the hydrolyzable functional groups of the silane coupling agent A method of obtaining a stimuli-responsive inorganic material particle by forming a modified atomic group by causing a condensation reaction between them may be adopted.

（但し、Ｈｙ₁，Ｈｙ₂，Ｈｙ₃：加水分解性官能基、Ａ：有機原子団、Ｐｉ：無機材料粒子、Ｓｔ：刺激応答性感応基） For example, as shown in the following general formula (3), a silane coupling agent (VI) having a stimulus-responsive sensitive group St is allowed to act on the inorganic material particles (I), and the inorganic material particles (I) By forming a condensation reaction between the surface hydroxyl group (OH) and the hydrolyzable functional group (Hy ₁ , Hy ₂ , Hy ₃ ) of the silane coupling agent (VI), a modified atomic group is formed and stimulated. Responsive inorganic material particles (VII) are obtained.

_{(However, Hy 1, Hy 2, Hy} 3: hydrolyzable functional group, A: an organic atomic group, Pi: inorganic material particles, St: stimulus-responsive sensitive group)

  In the production method of the present invention, substances other than aggregate particles may be mixed into the above mixture. For example, the production method of the present invention includes adding a relatively small amount of an organic binder or gelling agent as long as the effects of the production method of the present invention are not impaired. The amount of the organic binder or gelling agent added at this time is not particularly limited, but can be added within a range of 1 to 10 parts by mass with respect to 100 parts by mass of the aggregate particles. If it is less than the above range, the organic binder or gelling agent may not be able to exhibit its effect effectively. On the other hand, if it exceeds the above range, the viscosity becomes excessive when it is made into a slurry, which makes it difficult to handle and may cause problems due to a large amount of organic binder and the like. In consideration of this, the amount of the organic binder or gelling agent added is more preferably in the range of 1 to 3 parts by mass.

  As the organic binder, for example, hydroxypropylmethylcellulose, methylcellulose, hydroxyethylcellulose, carboxymethylcellulose, or polyvinyl alcohol can be suitably used. As the gelling agent, for example, a prepolymer such as polyisocyanate, epoxy resin, phenol resin or the like can be suitably used.

  In the production method of the present invention, a mixture containing stimulus-responsive inorganic material particles is molded into a desired shape to obtain a molded body precursor. The inorganic material particles to be the aggregate particles need to contain stimulus-responsive inorganic material particles, but not all of the inorganic material particles need to be stimulus-responsive inorganic material particles. Further, the form of the mixture may be a dry powder form, or a clay or slurry (slip) to which a dispersion medium is added. Examples of the dispersion medium include water or a mixed solvent of water and an organic solvent such as alcohol, and water is particularly preferably used.

  There is no restriction | limiting in particular about the method of shaping | molding, What is necessary is just to select suitably from conventionally well-known shaping | molding methods according to the form of a mixture. For example, a method in which aggregate particles are packed in a dense state, such as uniaxial press, isotropic press, cast molding, centrifugal molding, extrusion molding, electrophoresis method, filtration method, and magnetic field press, can be suitably used. In this way, a molded body of a mixture containing stimuli-responsive inorganic material particles is obtained. In the present specification, this molded body is referred to as a “molded body precursor”. This is because the molded body has not yet been formed with a bridging atomic group and can be regarded as a precursor of the molded body of the inorganic material of the present invention.

[2] Second Step In the second step of the production method of the present invention, an external stimulus is applied to the molded body precursor, and a binding reaction between a stimulus-responsive functional group and another functional group is used. This is a molded body manufacturing process in which an inorganic material molded body is obtained by forming a bridging atomic group for bonding inorganic material particles to each other.

  Specifically, an external stimulus that matches the type of stimulus-responsive functional group is applied to the molded body precursor produced as described above. For example, when the stimulus-responsive functional group is a phenyl azide group and the binding reaction proceeds with an amino group, ultraviolet light with a wavelength of 250 to 400 nm is irradiated for 5 to 120 minutes. Thereby, a coupling reaction proceeds between both functional groups, and a phenylhydrazo bond is formed. That is, an inorganic material molded body having a structure in which each of the inorganic material particles is bonded to each other by a bridging atomic group containing a phenylhydrazo group is obtained.

  When a combination of an amino group and a carboxyl group is used as the stimulus-responsive functional group, microwaves with a frequency of 2450 MHz are irradiated for 1 second to 30 minutes. Thereby, a coupling reaction proceeds between both functional groups, and an imide bond is formed. That is, an inorganic material molded body having a structure in which each of the inorganic material particles is bonded to each other by a bridging atomic group containing an imide group is obtained. In the case of microwaves, when the governments of each country have determined frequencies that can be used industrially, it is necessary to select the frequencies to be used in accordance with the frequencies. At present, in Japan, frequencies of 433.92 MHz, 2450 MHz, 5800 MHz, and 24.125 GHz can be used, and an appropriate frequency may be appropriately selected from these frequencies. In other countries, frequencies other than these frequencies (for example, 915 MHz (US), 896 MHz (UK), 2375 MHz (Eastern Europe / Russia), etc.) may be used.

  Further, when a combination of an amino group and a carboxyl group is used as the stimulus-responsive functional group, it may be heated at a relatively low temperature of 150 to 300 ° C. for 1 to 8 hours. Thereby, a coupling reaction proceeds between both functional groups, and an amide bond is formed. That is, an inorganic material molded body having a structure in which each of the inorganic material particles is bonded to each other by a bridging atomic group containing an amide group is obtained. In addition, when heating at 200 degrees C or less, it is preferable to heat on pressure reduction conditions. This is because the reaction is promoted by removing water generated by the dehydration reaction between the amino group and the carboxyl group out of the system, so that the coupling reaction proceeds even under a mild temperature condition of 200 ° C. or less.

  As a pattern of the bond formation, for example, as a raw material, at least a part of the aggregate particle includes i) the stimulus-responsive inorganic material particle and ii) an organic atomic group, and between the stimulus-responsive functional group Bonding with stimuli-responsive functional group using two types of modified inorganic material particles: a modified atomic group having a reactive functional group capable of forming a bond (bonding functional group) and a chemically modified binding inorganic material particle The pattern which forms the bridge | crosslinking atomic group which couple | bonds the modification atomic group of inorganic material particle | grains directly using the coupling reaction between a functional functional group, and couple | bonds inorganic material particle | grains mutually is mentioned.

In addition to the stimulus-responsive inorganic material particles, a polyfunctional organic compound having two or more binding functional groups is used as a raw material, and a binding reaction between the stimulus-responsive functional group and the binding functional group is utilized. It may be a pattern in which the modified atomic groups of the inorganic material particles are indirectly bonded to each other via a polyfunctional organic compound to form a crosslinked atomic group that bonds the inorganic material particles to each other. Examples of the polyfunctional organic compound include urea ((NH ₂ ) ₂ CO) and hexamethylene diamine (NH ₂ (CH ₂ ) NH having two amino groups capable of forming a bond with the phenyl azide group. ₂ ) etc. However, as long as two or more binding functional groups are capable of binding to a stimulus-responsive functional group, the types of functional groups do not have to be the same, and the types of functional groups may be different. .

  The inorganic material molded body obtained as described above may be used as it is, or may be used after drying under appropriate conditions. The drying method is not particularly limited, and conventionally known drying methods such as hot air drying, microwave drying, dielectric drying, reduced pressure drying, vacuum drying, freeze drying and the like can be used.

  In addition, it is also one of the preferable forms of this invention to obtain an inorganic material molded object by the manufacturing method of the inorganic material molded object of this invention, and baking the inorganic material molded object to obtain an inorganic material sintered compact ( Manufacturing method of binderless inorganic material sintered body). The inorganic material molded body obtained as described above is obtained by bonding aggregate particles made of an inorganic material to each other by a strong bond called a covalent bond via a bridging atomic group containing an organic atomic group. In addition to high shape retention after molding, the organic content is very low (about 1% or less of the total mass of the molded body after drying). Therefore, when this inorganic material molded body is fired, a high-quality inorganic material sintered body having high mechanical strength and few defects (voids and cracks) due to organic substances can be obtained. In addition, there is an advantage that the firing time can be shortened, carbon dioxide and harmful gas are hardly generated, and it does not cause global warming or air pollution.

  In this case, the removal of the organic matter can be further promoted by performing an operation (degreasing / calcination) for burning and removing the organic matter in the inorganic material molded body before firing or in the temperature raising process of firing. Is preferable. Since the combustion temperature of the organic substance is about 200 to 300 ° C., the calcining temperature may be about 200 to 1000 ° C. The calcining time is not particularly limited, but is usually about 10 to 100 hours.

  Hereinafter, the present invention will be described more specifically with reference to Examples and Comparative Examples. However, since the following examples show only some embodiments of the present invention, the present invention should not be construed as being limited to these examples.

Example 1
By using silica particles as inorganic material particles and chemically modifying a modified atomic group having a phenyl azide group (—C ₆ H ₄ —N ₃ ) as a stimulus-responsive functional group on the silica particles, the modified atoms An attempt was made to obtain stimuli-responsive silica particles having a structure in which nodules were covalently bonded to the silica particles.

First, as shown in the following formula (4), 3-aminopropyltriethoxysilane (II-a: NH ₂ C ₃ H ₆ Si (II-a), which is a silane coupling agent, is applied to the silica particles (Ia). OC ₂ H _{5) 3)} reacted to give a silanol-bonded silica particles (III-a).

  Specifically, 1.0 g of 3-aminopropyltriethoxysilane was dissolved in 100 ml of pure water to prepare an aqueous solution of a silane coupling agent, and an average particle diameter of 270 nm obtained by a sol-gel method was obtained in the aqueous solution. After dispersing 5.0 g of the silica particles and stirring for 1 hour, 3-aminopropyltriethoxysilane was adsorbed on the surface of the silica particles, and free 3-aminopropyltriethoxysilane was removed by centrifugal washing. Silanol-bonded silica particles having a structure in which silanol residues are covalently bonded to the silica particles by causing a condensation reaction between the silica particles and 3-aminopropyltriethoxysilane by heating and drying at ° C. Got.

When the obtained silanol-bonded silica particles were analyzed by infrared spectroscopy (IR), as shown in the IR chart of FIG. 1, a peak (3750) indicating surface hydroxyl groups (Si—OH) present in the silica particles before the reaction was obtained. / Cm ⁻¹ ) disappeared, and peaks (2940 / cm ⁻¹ , 2860 / cm ⁻¹ ) showing methylene groups (CH ₂ ) in silanol residues that did not exist in the silica particles before the reaction appeared. . The silanol-bonded silica particles were used not only as raw materials for the stimulus-responsive silica particles described later, but also as bondable silica particles to be bonded to the stimulus-responsive silica particles.

Next, as shown in the following formula (5), 4-azidobenzoic acid (IV-a: an organic compound having an azide group as a stimulus-responsive sensitive group) with respect to the silanol-bound inorganic material particles (III-a). N ₃ C ₆ H ₄ COOH) was allowed to act to obtain stimuli-responsive silica particles (Va).

Specifically, 4.5 g of silanol-bonded silica particles are dispersed in 300 ml of ethanol, 1.5 g of 4-azidobenzoic acid is added in a light-shielded state, and the mixture is stirred for 1 hour. -Adsorption of azidobenzoic acid and removal of free 4-azidobenzoic acid by centrifugal washing, followed by heating at 180 ° C for 6 hours under vacuum conditions, between silanol-bound silica particles and 4-azidobenzoic acid ( More specifically, a modified atomic group having a phenyl azide group is formed by causing an amidation reaction between an amino group at the end of a silanol residue of a silanol-bonded silica particle and a carboxyl group of 4-azidobenzoic acid. Stimulus-responsive silica particles having a structure in which a modified atomic group having a phenyl azide group is covalently bonded to silica particles Obtained. When the obtained stimulus-responsive silica particles were analyzed by infrared spectroscopy, as shown in the IR chart of FIG. 1, a peak (2120 / cm 2) indicating a phenyl azide group that was not present in the silanol-bonded silica particles before the reaction. ^-1 ) appeared.

  In a light-shielded state, 1.0 g of the above silanol-bonded silica particles (used here as bondable silica particles) and 1.0 g of stimuli-responsive silica particles are uniformly dispersed in 20 ml of ethanol to form a mixture, and this mixture is cast-molded. Was formed into a cylindrical shape having an outer diameter of 10.0 mmφ and a thickness of 3.0 mm to obtain a molded body precursor.

As shown in the following formula (6), the molded body precursor is irradiated with ultraviolet light having a wavelength of 366 nm, and the phenylazide group and silanol-bonded silica particles (III-a) of the stimulus-responsive silica particles (Va) are irradiated. ) Was allowed to proceed with the amino group to form a phenylhydrazo bond to obtain a silica molded product (VIII-a).

As a result of analyzing the obtained molded body by infrared spectroscopy (IR), it was confirmed that the peak (2120 / cm ⁻¹ ) indicating the phenyl azide group disappeared. That is, this silica molded body includes inorganic material particles made of silica and a bridging atomic group having the structure represented by the above formula (6) as constituent elements, and the bridging atomic group is shared with the inorganic material particles. Each of the inorganic material particles has a structure in which the inorganic material particles are bonded to each other by a bridging atomic group.

(Comparative Example 1)
A silica molded body was obtained in the same manner as in Example 1 except that ordinary silica particles not chemically modified were used as aggregate particles.

(Evaluation)
The silica molded body of Example 1 and the silica molded body of Comparative Example 1 were immersed in water. As a result, the structure of the silica molded body of Comparative Example 1 easily collapsed in water, and the water became cloudy. On the other hand, it was confirmed that the silica molded body of Example 1 was able to maintain its structure in water without water turbidity being observed.

  Further, the compression strength measurement was performed on the silica molded body of Example 1 and the silica molded body of Comparative Example 1 using a micro Vickers hardness meter (trade name: MVK-EL type (diamond indenter), manufactured by Akashi Seisakusho). . As a result, the silica molded body of Comparative Example 1 could only withstand a load of about 100 g. On the other hand, the silica molded body of Example 1 was confirmed to withstand a load of 200 g.

  Further, the stimuli-responsive silica particles produced in Example 1 and ordinary silica particles not chemically modified were subjected to thermal analysis, and the amount of organic matter was measured. As a result, as shown in the thermal analysis chart of FIG. 2, the ordinary silica particles only had desorption of adsorbed water when heated to about 200 ° C. In contrast, the stimuli-responsive silica particles were found to have undergone desorption of the chemically modified modified atomic groups upon heating up to 1000 ° C. The amount of organic matter calculated from this analysis result was about 0.8% by mass, which was confirmed to be extremely small.

(Example 2)
0.154 mmol of urea, which is a polyfunctional organic compound having two amino groups, in a dispersion obtained by uniformly dispersing 1.0 g of the stimulus-responsive silica particles prepared in Example 1 in 10 ml of ethanol in a light-shielded state Was added and dispersed again uniformly. To this dispersion, 1.0 g of the stimuli-responsive silica particles produced in Example 1 were uniformly dispersed in 10 ml of ethanol to obtain a mixture, and this mixture was cast to form an outer diameter of 10. The molded body precursor was formed into a cylindrical shape having a diameter of 0 mmφ and a thickness of 3.0 mm.

The molded body precursor is irradiated with ultraviolet light having a wavelength of 366 nm to cause a bonding reaction between the phenyl azide group of the stimulus-responsive silica particles and the two amino groups of urea to form a phenyl hydrazo bond. As a result, a silica molded body (VIII-b) having a bridged atomic group having a structure represented by the following formula as a constituent element was obtained. As a result of analyzing the obtained molded article by infrared spectroscopy, it was confirmed that the peak (2120 / cm ⁻¹ ) indicating the phenyl azide group disappeared, as in Example 1.

(Example 3)
Except that 0.154 mmol of hexamethylenediamine was used in place of 0.154 mmol of urea, the same as in Example 2, the reaction between the phenylazide group of the stimuli-responsive silica particle and the two amino groups of hexamethylenediamine A silica molded product (VIII-c) having a bridged atomic group having a structure represented by the following formula as a constituent element was obtained by allowing a bonding reaction between them to proceed to form a phenylhydrazo bond. As a result of analyzing the obtained molded article by infrared spectroscopy, it was confirmed that the peak (2120 / cm ⁻¹ ) indicating the phenyl azide group disappeared, as in Example 1.

(Evaluation)
The silica molded body of Example 2 and the silica molded body of Example 3 were immersed in water. As a result, it was confirmed that the silica molded bodies of Example 2 and Example 3 can maintain the structure in water. Further, the compressive strength measurement was performed on the silica molded body of Example 2 and the silica molded body of Example 3 using a micro Vickers hardness meter (trade name: MVK-EL type (diamond indenter), manufactured by Akashi Seisakusho). . As a result, the silica molded body of Example 2 withstood a load of 200 g, and the silica molded body of Example 3 withstood a load of 500 g. That is, it was confirmed that all can withstand a load of 200 g or more.

  The method for producing an inorganic material molded body of the present invention is suitably used for the production of various molded articles of ceramics and metals that are used in various applications such as structural materials and electrical / electronic materials.

It is IR chart which shows the result of having analyzed the silica particle, the silanol coupling | bonding silica particle, the stimulus responsive silica particle, and the silica molding by infrared spectroscopy. It is a thermal analysis chart which shows the result of having thermally analyzed the silica particle and the stimulus responsive silica particle.

Claims (14)

(A): Inorganic material particles that become aggregate particles, and (B): a bridging atomic group containing an organic atomic group as constituent elements,
The (B): bridging atomic group is covalently bonded to the (A): inorganic material particle, and the (A): inorganic material particle is mutually bonded by the (B): bridging atomic group. An inorganic material molded body having a combined structure. (B): the bridging group is selected from the group of phenylhydrazo group (—C ₆ H ₄ —NHNH—), amide group (—NHCO—), and imide group (—N (CO—) ₂ ). The inorganic material molded body according to claim 1, comprising at least one functional group. Oxide ceramics, non-oxide ceramics, and inorganic material particles made of at least one inorganic material selected from the group of metals and a bridging atomic group containing an organic atomic group as constituent elements, the bridging atomic group A method for producing an inorganic material molded body having a structure in which the inorganic material particles are bonded to each other by a covalent bond and each of the inorganic material particles is bonded to each other by the bridging atomic group.
First step: A modified atomic group containing an organic atomic group in the inorganic material particle and having a functional group (stimulus-responsive functional group) that causes a binding reaction with another functional group in response to an external stimulus. Using chemically-modified stimulus-responsive inorganic material particles as a raw material, a mixture containing the stimulus-responsive inorganic material particles is molded into a desired shape to obtain a molded body precursor,
Second step: The external stimulus is applied to the molded body precursor, and the inorganic material particles are bonded to each other using a binding reaction between the stimulus-responsive functional group and the other functional group. The manufacturing method of the inorganic material molded object which obtains the said inorganic material molded object by forming the said bridge | crosslinking atomic group. In addition to the stimulus-responsive inorganic material particle, the inorganic material particle includes an organic atomic group and has a reactive functional group (binding functional group) that can form a bond with the stimulus-responsive functional group. Using atomically bound, chemically bound inorganic material particles as raw materials,
Using the bonding reaction between the stimulus-responsive functional group and the binding functional group to bond the modified atomic groups to form the bridging atomic group that bonds the inorganic material particles to each other. Item 4. The manufacturing method according to Item 3. In addition to the stimulus-responsive inorganic material particles, a polyfunctional organic compound having two or more reactive functional groups (binding functional groups) capable of forming a bond with the stimulus-responsive functional group is used as a raw material.
The modification atomic groups are bonded to each other through the polyfunctional organic compound using a bonding reaction between the stimulus-responsive functional group and the binding functional group, and the inorganic material particles are bonded to each other. The manufacturing method of Claim 3 which forms the said bridge | crosslinking atomic group. By light irradiation, the binding reaction between the phenyl azide group (—C ₆ H ₄ —N ₃ ) as the stimulus-responsive functional group and the amino group (—NH ₂ ) as the binding functional group proceeds, to form a phenyl hydrazo bond (-C ₆ H ₄ -NHNH-), the method according to claim 4 or 5. By microwave irradiation, a binding reaction between the amino group (—NH ₂ ) as the stimulus-responsive functional group and the carboxyl group (—COOH) as the stimulus-responsive functional group proceeds, and an imide bond (— The production method according to claim 4 or 5, wherein N (CO-) ₂ ) is formed. By heating at 300 ° C. or lower, an amide bond is obtained by utilizing a bonding reaction between the amino group (—NH ₂ ) as the stimulus-responsive functional group and the carboxyl group (—COOH) as the stimulus-responsive functional group. The production method according to claim 4, wherein (—NHCO—) is formed. An inorganic material molded body is obtained by the production method according to any one of claims 3 to 8,
A method for producing an inorganic material sintered body, wherein the inorganic material molded body is fired to obtain an inorganic material sintered body. (C): inorganic material particles made of an inorganic material, and (D): a functional group containing an organic atomic group and causing a binding reaction with another functional group in response to an external stimulus (stimulus-responsive functional group) A modified atomic group having
(D): Stimulus-responsive inorganic material particles having a structure in which the modified atomic group is bonded to the (C): inorganic material particles by a covalent bond. Wherein (D): modified atomic group, stimulus-responsive inorganic material particles of claim 10 is one having a phenyl azide group (-C ₆ H ₄ -N ₃₎ as the stimuli-responsive functional group. Inorganic material particles made of an inorganic material, and a modified atomic group containing an organic atomic group and having a functional group (stimulus-responsive functional group) that causes a binding reaction with another functional group in response to an external stimulus. A method for producing stimuli-responsive inorganic material particles having a structure in which the modifying atomic group is covalently bonded to the inorganic material particles, comprising:
As the inorganic material particles, those made of oxide ceramics, non-oxide ceramics, and at least one inorganic material selected from the group of metals,
A method for producing stimuli-responsive inorganic material particles, wherein the inorganic material particles are chemically modified with the modified atomic group having the stimulus-responsive functional group. First step: A silanol residue is allowed to act on the inorganic material particles by causing a silane coupling agent to act on the inorganic material particles to cause a condensation reaction between the inorganic material particles and the silane coupling agent. Obtaining silanol-bonded inorganic material particles having a structure covalently bonded to the particles,
Second step: by causing the organic compound having the stimulus-responsive sensitive group to act on the silanol-bonded inorganic material particles and causing a bond-forming reaction between the silanol-bonded inorganic material particles and the organic compound. The manufacturing method according to claim 12, wherein the modified atomic group is formed to obtain the stimulus-responsive inorganic material particles. The organic compound, the stimulus-responsive functional groups used as a phenyl azide group _{(-C 6 H 4 -N 3)} , The method according to claim 12 or 13.

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