JP2008183640A - Diamond dispersed synthetic resin molding material and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a synthetic resin molding material of a monomer and a low grade polymer in which fine diamond particles of a sub micron class are dispersed and held in a primary particle state and its efficient manufacturing method. <P>SOLUTION: Constituent particles of graded diamond powder are dispersed in a non-agglomerated state in a synthetic resin material body including a molding resin monomer or oligomer. This synthetic resin molding material is effectively manufactured under a method including following steps: (1) a step to prepare the graded fine diamond powder a D<SB>50</SB>value average grain diameter of which is 1,000 nm or lower, a surface layer of the diamond particles of which is surface-reformed by a hydrophilic, hydrophobic or anti-diamond carbonizing process, (2) a step to disperse the surface reformed diamond particles in the molding material body including the molding resin monomer or oligomer and (3) a step to make the molding resin monomer or oligomer the resin molding body by polymerizing it. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a synthetic resin molding material in which finely divided diamond fine particles having a submicron grade particle size are individually dispersed in a resin in a primary particle state (non-aggregated state), and a method for producing the same.

  Along with the rapid advancement of precision machining, the tendency to use finer abrasive grains is also remarkable in the fields of cutting and polishing using diamond abrasive grains, aiming for smaller cutting allowance and angstrom level polished surface accuracy. Therefore, diamond particles of submicron class, particularly 500 nm or less, have been widely used.

  Even diamond, which is generally considered as a chemically stable substance, shows strong surface properties as the particle size decreases. It is recognized that Therefore, if it is used as it is by being fixed to the polishing tool, it apparently behaves as coarse particles, and there is a risk of damaging the work surface.

  Therefore, in the polishing process, diamond particles in the submicron region are put to practical use as a slurry dispersed in the form of isolated particles in an oily or aqueous medium (liquid). Free diamond abrasive grains in the slurry are held on a polishing disk or polishing cloth and contribute to processing, but the rate of retention is generally low, and the proportion of abrasive grains that flow out without contributing to processing cannot be ignored. Therefore, it is desired to develop a fixed abrasive tool in which abrasive grains are dispersed and fixed in a solid matrix.

  On the other hand, in cutting processing of electronic materials and the like, it is desired to improve the manufacturing yield of elements and the like by narrowing the cutting groove width as much as possible. As a solution to this problem, although a cutting tool using finer diamonds has been developed, a technique for uniformly dispersing fine diamonds on the tool working surface has not been solved.

By the way, it is publicly known that the submicron-grade diamond powder used as the aqueous slurry is subjected to an oxidation treatment in order to increase the hydrophilicity of the diamond particle surface.
Japanese Patent No.2691884

On the other hand, as a measure for preventing aggregation in dry powders for slurries using an oily medium, the present inventors previously fixed hydrogen atoms to dangling bonds (unbonded bonds) existing on the surface of diamond particles to stabilize them. It was found that it is effective. Based on this finding, submicron diamond powder which hardly aggregates is obtained by hydrogen-termination of active sites on the surface of diamond particles.
JP2001-329252

  Accordingly, one of the main objects of the present invention is that the submicron-class fine diamond particles are not aggregated, that is, are dispersed and held in the monomer or low polymer synthetic resin material in the form of primary particles. Another object is to provide a synthetic resin molding material. Another object is to provide a method by which such molding material can be produced efficiently.

  In one aspect, the present invention is characterized in that the constituent particles of the sized diamond powder are dispersed in a non-aggregated state in a synthetic resin raw material containing a molding resin monomer or oligomer. It relates to resin molding materials.

The synthetic resin molding material is effectively produced by a method that includes the following steps and constitutes another aspect of the present invention.
(1) preparing a finely divided fine diamond powder having a D ₅₀ value average particle size of 1000 nm or less, wherein the surface layer of the diamond particles is hydrophilized or hydrophobized or non-diamond carbonized;
(2) dispersing the surface-modified diamond particles in a molding raw material containing a monomer or oligomer of a molding resin; and
(3) A step of polymerizing a monomer or oligomer of the molding resin to obtain a resin molding.

  In the present invention, it is possible to effectively achieve a synthetic resin molding material in which nanometer-class fine diamond particles, which can only be used as a conventional slurry, are dispersed and held in a resin in a non-aggregated state. This molding material can be used for the production of tools of any shape, and in particular, it can be applied to polishing tools to obtain tools suitable for precision cutting or precision processing. Therefore, productivity can be improved by the effective use of abrasive grains. In addition to reducing processing costs, it is also possible to reduce the burden on the environment by reducing the amount of waste.

  In addition, the present invention has a structure in which fine diamond particles are held as primary particles in the resin, thereby imparting wear resistance to the resin and can be used as a lightweight structural material in place of metal and ceramics. It is what.

  In the present invention, a synthetic resin molding material in which fine diamond is contained at a high degree of dispersion in the molding resin is effectively obtained, and this high dispersibility is exhibited particularly in a fine particle size region. For example, because it can be effectively applied to powders in the submicron range, sufficient mixing is achieved between diamond abrasive grains and synthetic resin as a matrix component, which was extremely difficult with conventional methods in the manufacturing process of polishing tools. Is done.

The method of the present invention can be applied to fine diamond particles, and is effectively applied to finely sized diamond powder (particle aggregate) having a D ₅₀ average particle size of 1000 nm (1 μm) or less to effectively disperse primary particles. It is possible to make a body. A diamond powder having a D ₅₀ average particle diameter exceeding 1000 nm has a specific surface area as small as 6 m ² / g or less, the surface state is relatively stable, and aggregation between primary particles does not need to be considered. Therefore, for the dispersion of such a relatively coarse diamond powder in the synthetic resin material, the conventional method of kneading directly into the molding raw material can be used, and the method of the present invention is not necessarily required.

Therefore, in the present invention, the fine diamond powder dispersed in the resin material has a particle size of not more than 1000 nm, particularly not more than 500 nm, more preferably not more than 200 nm in terms of a D ₅₀ value average particle size. Powder refers to an aggregate of particles. The size (particle size) of each particle constituting the powder has a distribution width that varies depending on the classification accuracy on both sides of the average value expressed as the D ₅₀ value, which is typically D ₁₀ and D with respect to the D ₅₀ value. Characterized by a ratio of ₉₀ . Since precision processing polishing particularly requires a reduction in the content of coarse particles, in the present invention, these parameters D ₁₀ / D ₅₀ highly sized by a precision classification operation developed by the present inventors. And it is desirable to use precision classified products having a ratio of D ₉₀ / D ₅₀ of 0.5 or more and 1.8 or less, respectively.
Patent 3655811 JP2004-339412

  The particle size of each particle can be 1800 nm (1.8 μm) or less. Larger particles can be mixed with the abrasive tool matrix material by conventional dry or wet mixing methods, while conventional means can be difficult to maintain suspension in organic media. Therefore, it is excluded from the processing target of the present invention. On the other hand, the lower limit can be up to 3 nm, the smallest size available at present. The diamond content in the synthetic resin molding material is preferably 50 (12.5 vol%) or less, more preferably 25 or less in terms of concentration, since the particle size of each individual particle is small.

  From the viewpoint of polishing performance, the diamond particles used in the present invention are particularly preferably single crystalline diamonds that have been converted from non-diamond carbon under high temperature static ultrahigh pressure and then subjected to crushing and classification steps. So-called polycrystalline diamond synthesized by detonation or the like can also be used.

  In the case of single crystalline diamond, for example, refinement by impact crushing by dropping an iron ball using a ball mill is effective. Since the crushing mechanism in single crystalline particles is led by cleaving cracks, crushing pieces with sharp edges can be obtained. Prior to the crushing operation, the raw material diamond charged in the ball mill is heated to 1000 ° C. or more to form a large number of microcracks in the diamond particles, thereby increasing the crushing efficiency.

  As diamond particles to be included in the molding resin, polycrystalline agglomerated diamond particles which were synthesized under a dynamic ultrahigh pressure and passed through a crushing process were also generated at the time of synthesis if they substantially showed a diamond structure. It can be used similarly because it can be agglomerated and suspended in a dispersion medium in a state close to a single particle.

  There are cases where polycrystalline agglomerated diamond particles use graphite as the starting material and high-performance explosives with a high carbon content. Since it is a short time, the primary particle size is on the order of several to several tens of nanometers, and usually exhibits a spherical shape in order to keep the surface energy small.

  In addition, polycrystalline diamond starting from graphite is fused by primary particles, while polycrystalline diamond originating from explosives is more than 100 nm due to strong agglomeration that may be due to bonding via functional groups and atoms on the surface. Secondary particles. These secondary particles can also be crushed or agglomerated by impact crushing and chemical treatment in a later step.

The bonds between carbon atoms in the diamond crystal are usually SP ³ bonds, but the diamond used in the present invention does not necessarily maintain the SP ³ bonds as a whole, and the particle surface layer has a graphite SP ² structure ( It may exhibit a graphene structure).

  The molding resin material used in the present invention can be selected from a wide range, for example, selected from phenol, polyimide, urethane, acrylic, epoxy, melamine, polycarbonate, polyacetal, polyvinyl, cellulose acetate One kind or a combination of plural kinds is used.

In the present invention, the surface of the particle is made hydrophilic or hydrophobic, or made non-diamond carbon structure (graphene), depending on the type of the resin material to be dispersed, the molding resin material containing the oligomer, and the dispersion medium / solvent. Use diamond with surface modification. These treatments can be accomplished by oxidation, hydrogen termination, or heating in vacuum, respectively, as follows.

  The surface of the diamond particles is hydrophilized by heating in an oxygen-containing atmosphere of 300 to 450 ° C., for example, heating in air or oxygen gas (dry treatment), or concentrated sulfuric acid heated to 150 ° C. or more, particularly 250 to 350 ° C. It is effective to immerse in fuming sulfuric acid and to heat (wet treatment) in the presence of oxidizing agents such as nitric acid, perchloric acid, chromic acid, permanganic acid and nitrate. By these treatments, bonding or adsorption of hydrophilic oxygen-containing functional groups such as C═O, COO, and OH is recognized on the diamond particle surface by infrared absorption analysis.

  Infrared absorption analysis has confirmed that hydrophilic oxygen-containing functional groups such as carbonyl, carboxyl, and hydroxyl groups are present in an adsorbed or bonded state on the surface of the diamond subjected to the hydrophilization treatment. It is understood that dangling bonds that are triggered by the elimination of these functional groups during heating are the starting points, and the bonds that occur between adjacent particles are the origin of aggregation.

  Hydrophobization of the diamond surface can be effectively achieved by hydrogen termination of the diamond particle surface. This is a treatment that chemically stabilizes hydrogen atoms by bonding them to unbonded bonds existing on the surface of diamond particles. This treatment is particularly effective for preventing aggregation in dry powders for slurries using oily media. It is effective as

According to the knowledge of the present inventors, the hydrogen termination effect is recognized from around 500 ° C. in heating in a hydrogen atmosphere. That is, the absorption peak height attributed to OH stretching, which was observed in the vicinity of 3000 to 3600 cm ⁻¹ in the infrared absorption analysis, was reduced, and instead was not recognized in the surface hydrophilic diamond, but near 2800 to 3000 cm ^−1. An absorption peak attributed to the CH stretching observed in FIG. This absorption peak becomes prominent when heated at 600 ° C., and an absorption peak attributed to OH stretching is generally not observed in the heat treatment at 800 ° C., so it is considered that the hydrogen termination treatment is almost completed. During this time, it is recognized that a reaction in which hydrogen is bonded to and stabilized by dangling bonds generated by desorption of oxygen from the C—O bond site is also advanced.

Furthermore, even if the heating is continued at a temperature exceeding 800 ° C., the desorption of CO gas from the diamond surface is observed, so that it is estimated that there is oxygen that is firmly bonded to the diamond surface. Therefore, heat treatment at a temperature of 800 ° C. or higher in hydrogen is effective for removing bound oxygen from the diamond surface. However, when the heat treatment exceeds 1000 ° C., the SP ³ structure on the surface of the diamond powder particles collapses and becomes a structure covered with non-diamond carbon of SP ² , and the hydrogen termination effect tends to be unclear.

  Therefore, for the purpose of the present invention, it is efficient to perform the heat treatment in a hydrogen atmosphere for hydrogen termination at a treatment temperature (hydrogen termination temperature) of 500 ° C. or higher and 1000 ° C. or lower, particularly 600 ° C. or higher and 800 ° C. or lower. Is appropriate.

In the hydrogen termination treatment in the present invention, the absorption peak height attributed to CH stretching observed in the vicinity of 2800 to 3000 cm ⁻¹ in the absorption spectrum of the powder by a Fourier transform infrared spectrophotometer (FTIR) is 3000 to This is performed until the height of the absorption peak attributed to the OH stretching observed at around 3600 cm ⁻¹ is reached.

  In the present invention, the hydrogen termination treatment can improve the treatment effect by preliminarily hydrophilizing the diamond to be treated. That is, prior to the hydrogen termination treatment by heating in a hydrogen atmosphere, when the above-described hydrophilization treatment is performed on the diamond powder, oxygen such as C = O, COO, OH or the like is obtained by a substitution reaction between oxygen and hydrogen. The disappearance of the contained functional group and the appearance of the CH bond can be confirmed by infrared absorption analysis.

The carbon atom on the outermost surface of the diamond particle is bonded to hydrogen, which is considered to be the most stable state by hydrogen termination treatment (hydrogen termination), and the surface carbon atom can maintain the same SP ³ structure as the inside of the particle. . At the same time, hydrophobicity (lipophilicity) is imparted to the diamond particles, making it easy to disperse in an oily dispersion medium (organic medium) made of an organic compound. Uniform dispersion in the resin material is possible.

  In experiments by the present inventors, diamond powder having an average particle diameter of 50 nm is suspended in a solvent for 6 hours after dispersion up to 0.34% in propanol, 0.41% in acetone, and 0.17% in vinyl acetate monomer. The result of maintaining the state was obtained. That is, it is understood that the diamond surface is wet with these solvents. Further, immediately after the ultrasonic dispersion, it is possible to cause the diamond having the above concentration to exist in a pseudo-suspended state.

  In the method of the present invention, diamond can be combined with a synthetic resin in several ways. For example, the diamond particles are dispersed and suspended in advance in a solvent having compatibility or solubility with respect to the molding resin, and then this dispersion suspension is mixed with the molding resin in a monomer or oligomer state. Alternatively, after the diamond particles are dispersed and suspended in an organic medium, the resin molding material is added and dissolved, and the whole is mixed to achieve dispersion in the resin molding material. Alternatively, diamond particles can be added after the resin raw material is dissolved and mixed in an organic medium.

  It has been observed that the hydrophilic surface has a higher dispersion concentration in the organic medium. For example, for methyl methacrylate, the upper limit of the dispersible concentration of diamond whose surface is hydrophilized and hydrophobized is 0.34% and 0.22%, respectively, and ethyl acetate is 0.24% and 0.18%, respectively.

  In general, the monomer of the molding resin raw material is often a volatile liquid, and the oligomer with a low polymerization degree is often viscous liquid. The molding raw material includes the two states described above, but also includes forms such as granules and pellets. As a method of dispersing fine diamond powder in these, in the case of a liquid monomer, diamond is directly dispersed and suspended in the liquid by ultrasonic dispersion or a mixing method using a dispersion medium, and then precipitated. Diamond is separated and used as agglomerated particles.

  Diamond is dispersed and suspended in advance in a compatible solvent for oligomers and in a solvent that is soluble for solid molding resin materials. After mixing with the resin raw material, the solvent is evaporated and removed. Thus, the fine diamond can be dispersed in the resin of the molding material in a state close to primary particles or primary particles.

  When these solvents are used, the amount of the solvent as the dispersant increases, but the dispersion concentration of diamond in the resin of the molding resin material can be controlled to an arbitrary value.

  When fine diamond is dispersed / suspended in a liquid monomer or dispersion medium, the surface of the diamond particles can be processed as necessary to improve the dispersion / suspension performance. This method includes heat treatment in an atmospheric gas or an oxidizing agent, and surface modification using a surfactant or the like. By these treatments, it is possible to change the kind of different atoms, functional groups and molecules bonded or attached to the carbon atoms on the outermost surface of the powder particles, or change the bonding state of the carbon atoms.

The clear difference in the effect of making the diamond surface hydrophilic and hydrophobic is that the amount of stable suspension of deionized water and acetone in a diamond with a D ₅₀ value of 50 nm is 2.7% for both hydrophilic and hydrophobic. And 0.08%, and 0.02% and 0.4% in the experimental examples.

In the present invention, diamond particles are subjected to heat treatment in an oxygen-free atmosphere at a temperature higher than the hydrogen termination temperature, and the carbon atoms on the diamond particle surface are made non-diamond, that is, particles having an SP ² structure (graphene structure). Can also be used.

As a heating phenomenon of the diamond particles, it is confirmed by Raman spectroscopic analysis that carbon atoms on the surface of the diamond particles have an SP ² structure due to bonding between dangling bonds generated by detachment of terminal atoms or functional groups on the particle surface, It is known that the surface becomes stable. The temperature at which the surface changes to the SP ² structure depends on the particle size, that is, the activity (unstable) degree of the surface, and shifts to the low temperature side as the particle size decreases. The appearance of a clear SP ² structure has already been observed in heating at 700 ° C.

  For diamond particles having such a surface structure, it is often effective to preliminarily attach a surfactant to the particle surface prior to a dispersion suspension operation in a monomer or an organic solvent. Various types of surfactants can be used, but nonionic surfactants are particularly preferable from the viewpoint of avoiding the coexistence of foreign substances.

  An example of proper use of hydrophilic and hydrophobic diamond is as follows. In the production process of polycarbonate resin material by interfacial polycondensation method in which caustic soda is added to bisphenol A, surface hydrophilic submicron diamond is suspended in an aqueous caustic soda solution in advance. It is possible to uniformly disperse diamond in the obtained base polymer, and it can be made into a diamond-containing tool or wear-resistant resin material through various steps of pelletization and high temperature molding at about 300 ° C. it can.

  As a method of using surface hydrophobic diamond, bisphenol A is synthesized by a reaction of acetone and bisphenol in which surface hydrophobic diamond is dispersed, or after bisphenol A is once dissolved in acetone in which diamond is dispersed. It is also possible to disperse diamond in bisphenol A by evaporating and separating acetone.

  When fine diamond powder is dispersed in the molding raw material in the present invention, it has the ability to disperse and suspend the diamond powder, and is compatible with the molding raw material or has the ability to dissolve the molding raw material. A dispersion medium can be used. Water-based, alcohol-based, ketone-based, chain hydrocarbon, cyclic hydrocarbon, and the like are used as the type of dispersion medium suitable for the surface state (hydrophilicity, hydrophobicity, graphene structure) of diamond powder particles. Since these dispersion media are separated and removed prior to the polymerization reaction in the molding raw material, it is preferable to use an organic agent having a relatively low boiling point.

  Various methods such as the following can be used to disperse the diamond powder. For example, as a dispersion medium for dispersing and suspending diamond powder and a medium for dissolving a molding raw material, different kinds of organic media having the same type or mutual solubility (compatible) are used, and these solutions or dispersions are used. It is extremely effective to mix both liquids after forming a suspension.

  Alternatively, after the diamond powder is dispersed and suspended in an organic medium, the forming raw material can be added and dissolved in a solid / powder or fluid state, and the whole can be mixed and homogenized.

  Alternatively, the molding raw material is dissolved in an organic medium, mixed and homogenized, and then diamond powder particles are added to the solution, or the solution is allowed to penetrate into the gaps between the diamond-terminated aggregates. It is valid.

  For an organic medium, that is, a solvent or a dispersion medium, it is possible to increase the time during which diamond particles are held in a suspended state by increasing the addition concentration of the resin material to increase the viscosity of the medium. The organic medium to which the diamond particles and the resin material are added is subjected to various known methods such as stirring, ultrasonic irradiation, bead mill mixing, paint shaker, etc., as necessary, so as to ensure uniform mixing of the diamond and the resin. To.

  After the diamond powder particles combined with the forming raw material and dispersed / suspended in the medium are uniformly mixed, for example, the dispersion medium and the solvent are evaporated and removed by heating under normal pressure or reduced pressure. The synthetic resin molding material holding the diamond powder particles in a dispersed state can be recovered in the form of liquid, powder or flakes.

  In the case of a dispersion medium that contains diamond particles in a suspended state exceeding the suspension limit, the resin and diamond are intimately mixed by using the instantaneous drying method of mixed products including spray drying as the drying method. A raw material body is obtained.

  For use as a polishing tool, a thermoplastic resin can be used as the resin material that forms the matrix and fixes the diamond particles. However, from the standpoint of avoiding the trouble of softening due to polishing heat during use, it is thermosetting. A resin is more preferable. Examples of such resins include phenol resin, epoxy resin, melamine resin, urea resin, urethane resin, alkyd resin, unsaturated polyester, and the like. Furthermore, these composite articles, so-called polymer alloys can also be used.

  As an organic medium (that is, a dispersion medium or a solvent) used in the present invention, the above-described resin raw materials and precursors are dissolved, the affinity to hydrogen-terminated diamond is high, and the properties of the resin material are not significantly changed. Substances which can be separated by distillation in the temperature range, in particular those having a boiling point of 120 ° C. or less are preferred. Such an organic medium can be selected from a wide range such as alcohols, ketones, chain hydrocarbons, cyclic hydrocarbons, and acetates.

  Since these organic media can be recovered by distillation and used repeatedly, media with low dispersibility (suspension limit) of diamond can also be used. In addition, since the dispersion medium and the solvent can be recovered in a temperature range that does not cause alteration of the resin material by using vacuum distillation means, in this sense, the condition of low boiling point is not an essential requirement for the organic medium.

  When the organic medium is removed from the organic medium in which the diamond and the resin are uniformly mixed, a liquid or powder or flaky synthetic resin molding material in which submicron diamond fine powder is dispersed and fixed in a primary particle state is obtained. can get.

  On the other hand, when a polishing tool is manufactured, a resin lump containing diamond is formed into islands in the resin ground by mixing submicron diamond-dispersed resin and resin-only powder and filling and molding the mold. It is also possible to have a configuration dispersed in the above.

  The obtained synthetic resin molding material can be molded into a tool or a wear-resistant material using a normal resin molding technique. In particular, a pressure molding method using a heating means such as hot pressing or injection molding is preferable, and a fine diamond particle-dispersed tool or tool material substantially free of pores can be obtained. When the presence of pores does not become an obstacle, a casting method can be used, and a sheet can be formed by rolling or roll forming as necessary.

  When manufacturing thin resin-based diamond tools (for example, cutting blades), inorganic fibrous materials, ceramic fibers (glass, alumina, silicon carbide, silicon nitride, etc.), carbon fibers, carbon It is preferable to add nanofibers as necessary. At this time, it is also effective to add, for example, a nonionic surfactant for the purpose of dispersing the reinforcing agent.

Subsurface micron diamond MD50 (D ₅₀ = 53 nm, specific surface area 130 m ² / g) is introduced into 500 ml of methyl methacrylate (MMC) monomer, dispersed with an ultrasonic homogenizer for 5 minutes, and left at room temperature for 1 hour. did. Next, about 400 ml of the suspended diamond suspension was transferred to another beaker, and 1 g of benzoyl peroxide was added, mixed and poured into a 300 mm diameter mold for the purpose of separation from the aggregates. A finish polishing machine was produced. From the observation of the SEM test piece produced at the same time, most of the diamond particles in the cured acrylic resin were isolated particles. The diamond concentration in the resin was estimated to be 0.35% by subtracting the diamond weight remaining as a sedimentation part in the above-mentioned standing operation.

Surface suspension diamond MD100 (D ₅₀ = 103 nm, specific surface area 53 m ² / g) 5 g dispersed in 100 ml deionized water and 200 ml vinyl acetate monomer as starting materials and emulsion polymerized to form a paint A viscous liquid was obtained. This liquid was applied to a cherry wood polishing plate having a diameter of 100 mm and a thickness of 10 mm and cured, and used as a metal specimen polishing plate for microscopic observation sample production.

Hydrogen-terminated diamond MD100-OB (D ₅₀ = 105 nm, specific surface area 59 m ² / g) 3 g in 2000 ml of acetone was dispersed and suspended, and then cellulose acetate (acetylation degree 55) 150 g was added and dissolved. A grayish cloudy solution was obtained. This liquid was poured onto a plate glass and dried at 150 ° C. to obtain a diamond-containing wear-resistant sheet material having a thickness of about 50 μm.

As shown in the following table, diamond subjected to hydrophilization, hydrogen termination or surface graphene treatment was combined with various molding raw material bodies to prepare diamond-dispersed resin molded bodies.

Claims (27)

  A synthetic resin molding material, wherein the constituent particles of the sized diamond powder are dispersed in a non-aggregated state in a synthetic resin raw material containing a monomer or oligomer of the molding resin. D ₅₀ value average particle size of the diamond powder is 1000nm or less, synthetic resin molding material of claim 1. D ₅₀ value average particle size of the diamond powder is 500nm or less, synthetic resin molding material according to claim 2. D ₅₀ value average particle size of the diamond powder is 200nm or less, synthetic resin molded material according to any one of claims 2 and 3. The ratio of ₁₀ values and D ₉₀ values D for D ₅₀ value average particle size of the diamond powder is 0.5 or more and 1.8 or less, respectively, synthetic resin molded material according to any one of claims 1 to 4.   The synthetic resin molding material according to claim 1, wherein the constituent particles are diamond particles having a primary particle size of 1.8 µm or less and 3 nm or more.   The synthetic resin molding material according to claim 1, wherein the constituent particles are single crystalline diamond particles synthesized under static ultrahigh pressure and subjected to crushing and classification steps.   The synthetic resin molding material according to claim 1, wherein the constituent particles are polycrystalline agglomerated diamond particles synthesized under a dynamic ultrahigh pressure and subjected to a crushing step. The synthetic resin molding material according to claim 1, wherein carbon atoms on the surface of the constituent particles maintain the SP ³ structure. Carbon atoms constituting the particle surface has a SP ² structure (graphene), a synthetic resin molding material of claim 1.   The synthetic resin according to claim 1, wherein the molding resin contains one or more selected from phenol, polyimide, urethane, acrylic, epoxy, melamine, polycarbonate, polyacetal, polyvinyl, and cellulose acetate. Molding material. Method for producing fine diamond particle-dispersed synthetic resin molding material containing the following steps:
(1) preparing a finely divided fine diamond powder having a D ₅₀ value average particle size of 1000 nm or less, wherein the surface layer of the diamond particles is hydrophilized or hydrophobized or non-diamond carbonized;
(2) dispersing the surface-modified diamond particles in a molding raw material containing a monomer or oligomer of a molding resin; and
(3) A step of polymerizing a monomer or oligomer of the molding resin to obtain a resin molding.   In the step (1), the hydrophilization treatment of diamond particles is immersed in concentrated sulfuric acid or fuming sulfuric acid heated to a bath temperature of 150 ° C. or higher to bind or adsorb hydrophilic functional groups on the surface of the diamond particles. The method of claim 12, wherein   The method of claim 13, wherein the bath temperature is 250 ° C. or higher.   The method according to claim 13, wherein the concentrated sulfuric acid and fuming sulfuric acid further contain at least one oxidizing agent selected from nitric acid, perchloric acid, chromic acid, permanganic acid and nitrate.   In the step (1), the hydrophilization treatment of diamond particles is performed by heating to a treatment temperature of 300 ° C. or higher in an oxygen-containing atmosphere, and bonding or adsorbing hydrophilic functional groups on the surfaces of the diamond particles. 12. The method according to 12.   The method according to claim 12, wherein in the step (1), the diamond particles are hydrophobized by heating to a hydrogen termination temperature in a hydrogen atmosphere and hydrogen termination.   The method according to claim 17, wherein the diamond powder is subjected to an oxidation treatment to bond or adsorb a hydrophilic functional group on the surface of the diamond particle prior to heating to a hydrogen termination temperature in a hydrogen atmosphere.   The method of claim 18, wherein the oxidation treatment comprises immersion in a heated concentrated sulfuric or fuming sulfuric acid bath.   The method according to claim 18, wherein the oxidation treatment includes heating in an oxygen-containing atmosphere. In the hydrogen termination treatment, the absorption peak height attributed to CH stretching observed in the vicinity of 2800 to 3000 cm ⁻¹ in the absorption spectrum of the powder by a Fourier transform infrared spectrophotometer (FTIR) is set to 3000 to 3600 cm ^−. The method according to claim 12, wherein the absorption peak height is equal to or greater than the height of the absorption peak attributed to OH stretching observed in the vicinity of ¹ .   The method according to each of claims 17 to 21, wherein the hydrogen termination temperature is 500 ° C or higher and 1000 ° C or lower.   The method according to claim 22, wherein the hydrogen termination temperature is 600 ° C. or higher and 800 ° C. or lower. The method according to claim 12, wherein the non-diamond carbonization of the diamond particles is performed by heating in an oxygen-free atmosphere to form a diamond particle surface with an SP ² bond structure.
In the step (2), the diamond particles are preliminarily dispersed and suspended in a solvent having compatibility or solubility with respect to the molding resin, and the dispersion suspension is mixed with the synthetic resin material. Method.   The method according to claim 12, wherein in the step (2), the diamond particles are dispersed and suspended in an organic medium, and then the molding resin is added and dissolved, and the whole is mixed. The method according to claim 12, wherein in the step (2), the diamond resin is added after the molding resin is dissolved and mixed in an organic medium.