JP6774175B2 - Non-conductive materials and paints - Google Patents

Description

The present invention relates to non-conductive materials and paints.

Conventionally, as a cover material (for example, a sealing material) for an electronic component such as a semiconductor chip, a paint having a high insulating property that does not short-circuit between wirings while having a sufficient light-shielding property has been used (for example, a patent). Document 1). As the black pigment used in such paints, carbon powders such as chromium-based black pigments, organic pigments, and carbon black are used. However, the cover material formed by using the chromium-based black pigment and the organic-based pigment tends to have an insufficient degree of black shielding and a high material cost. Further, carbon black has excellent coloring property and is inexpensive, but on the other hand, it has conductivity, so that it is not suitable for applications requiring non-conductive property. Therefore, there is a demand for a black pigment having sufficient light-shielding properties and high insulating properties.

Japanese Unexamined Patent Publication No. 2003-335922 Japanese Unexamined Patent Publication No. 8-259838

Patent Document 2 describes that a non-conductive carbonaceous powder in which at least a part of carbon black is coated with insulating fine particles is used as the black pigment. According to the publication, by coating carbon black with insulating fine particles, the conductivity of carbon black can be eliminated and suitable insulating properties can be imparted to the coating film. However, in the configuration in which the carbon black is coated with the insulating fine particles as in Patent Document 2, the insulating fine particles are easily peeled off from the carbon black, and there is a drawback that the insulating property and the light shielding property cannot be stably maintained when the coating film is formed. is there. Further, there is a problem that the process of coating carbon black with insulating fine particles is complicated and the coating film formation becomes expensive. It would be useful if a technique for eliminating the conductivity of the carbon particles themselves was provided without using an insulating film.

The present invention has been made in view of this point, and a main object thereof is to provide a non-conductive material made of carbon particles suitable for applications requiring non-conductive and light-shielding properties.

As a result of diligent studies to solve the above problems, the present inventor has found that the conductivity of carbon particles can be effectively eliminated by containing a predetermined amount of oxygen elements in the amorphous carbon particles. Found and completed the present invention.

That is, the non-conductive material provided by the present invention is a non-conductive material composed of amorphous non-conductive carbon particles. This non-conductive material has a carbon element content of at least 70% by mass and an oxygen element content of 9% by mass to 30% by mass as determined by energy dispersive X-ray spectroscopy (EDX). .. By containing 9% by mass to 30% by mass of an oxygen element in the amorphous carbon particles in this way, the conductivity of the carbon particles which are originally conductive is eliminated, and the insulating carbon particles are separated from the carbon particles. Can be a non-conductive material. Since the carbon particles themselves are insulating materials, such non-conductive materials can stably exhibit non-conductive properties and light-shielding properties for a long period of time. Therefore, such non-conductive materials are suitable for applications requiring non-conductive and light-shielding properties (for example, integrated circuits (ICs), large-scale integrated circuits (LSIs), encapsulants for electronic components such as transistors). It can be suitably used as (typically a black pigment).

In the present specification, "conductivity" refers to a property exhibited by a material having a volume resistivity (volume resistivity (volume specific electrical resistance value) of less than 1 × 10 ⁶ Ω · cm, and “non-conductive” means. the volume resistivity (volume specific resistance value) refers to the property indicated by the 1 × 10 ⁶ Ω · cm or more materials. The volume resistivity referred to in the present specification is that the test powder is placed in a cylindrical pipe (inner diameter of 10 mm) made of Duracon and pressurized at 1000 kg, and the volume resistivity of the green compact is multimetered at room temperature. The values measured using are shown. Here, "room temperature" refers to a temperature range of 15 to 35 ° C., and typically refers to a temperature range of 20 to 30 ° C. (for example, 25 ° C.).

In a preferred embodiment of the non-conductive material disclosed herein, the content of the oxygen element is 20% by mass to 30% by mass. When the content of the oxygen element is within the range, the conductivity of the carbon particles can be more effectively eliminated. Therefore, may higher insulation (e.g. volume resistivity is the 5 × 10 ⁸ Ω · cm or more) non-conductive material is achieved.

In a preferred embodiment of the non-conductive material disclosed herein, it is substantially free of additional constituent elements other than the carbon element and the oxygen element. Thereby, both non-conductive property and light-shielding property can be realized at a higher level.

The present invention also provides a coating as another aspect. The coating material contains any of the non-conductive materials disclosed herein and a liquid medium. Such a paint can be suitably used for various purposes as a paint for giving a non-conductive black coating.

FIG. 1 is a diagram showing X-ray diffraction patterns of Examples 1 to 4. FIG. 2 is a diagram showing an X-ray diffraction pattern of Examples 5 to 8. It is a figure for demonstrating the measuring method of volume resistivity.

Hereinafter, preferred embodiments of the present invention will be described. Matters other than those specifically mentioned in the present specification and necessary for carrying out the present invention (for example, a method for producing a raw material for a non-conductive material) are based on the prior art in the art. It can be grasped as a design matter of a person skilled in the art. The present invention can be carried out based on the contents disclosed in the present specification and common general technical knowledge in the art.

<Non-conductive material>
The non-conductive material disclosed here is a non-conductive material composed of amorphous non-conductive carbon particles. This non-conductive material has a carbon (C) element content of at least 70% by mass and an oxygen (O) element determined by Energy Dispersive X-ray Spectroscopy (EDX). The content of is 9% by mass to 30% by mass. By containing 9% by mass to 30% by mass of an oxygen element in the amorphous carbon particles in this way, the conductivity of the carbon particles which are originally conductive is eliminated, and the insulating material is non-conductive. A non-conductive material made of carbon particles can be realized. Since the carbon particles themselves are insulating materials, such non-conductive materials can stably exhibit non-conductive properties and light-shielding properties for a long period of time. Whether or not the non-conductive material (carbon particles) is amorphous can be confirmed by, for example, the result of measurement by an X-ray diffractometer showing a broad pattern.

<Oxygen element content>
The content (mass basis) of the oxygen element in the non-conductive material is preferably about 9% by mass or more from the viewpoint of eliminating conductivity, and is usually 10% by mass or more, preferably 15% by mass. As mentioned above, it is more preferably 20% by mass or more, still more preferably 25% by mass or more. Further, the mass-based content of the oxygen element is preferably 30% by mass or less, preferably 28% by mass or less, from the viewpoint of achieving both non-conductiveness and light-shielding property (coloring property). is there. For example, a non-conductive material having an oxygen element content of 9% by mass or more and 30% by mass or less is preferable, and a material having an oxygen element content of 15% by mass or more and 28% by mass or less is particularly preferable. When the content of the oxygen element is within the range, high insulation and good light-shielding property can be achieved at a high level.

Further, assuming that the total number of atoms present in the non-conductive material is 100 atom%, the content of oxygen atoms based on the atomic number is preferably 5 atom% or more, more preferably 7 atom, from the viewpoint of eliminating conductivity. % Or more, more preferably 10 atom% or more, and particularly preferably 14 atom% or more (for example, 20 atom% or more). Further, the content of the oxygen atom based on the number of atoms is preferably 30 atom% or less, more preferably 25 atom% or less, from the viewpoint of better achieving both non-conductiveness and light-shielding property. The technique disclosed here can be preferably carried out, for example, in an embodiment in which the content of oxygen atoms based on the number of atoms is 7 atom% or more and 25 atom% or less.

<Carbon element content>
The content of carbon element (based on mass) in the non-conductive material is preferably 95% by mass or less, preferably 91% by mass or less, and more preferably 85% by mass, from the viewpoint of eliminating conductivity. Below, it is more preferably 80% by mass or less, and particularly preferably 75% by mass or less. Further, the mass-based content of the carbon element is preferably about 70% by mass or more, preferably 72% by mass or more, from the viewpoint of achieving both non-conductive property and light-shielding property. For example, a non-conductive material having a carbon element content of 70% by mass or more and 91% by mass or less is preferable, and a material having a carbon element content of 72% by mass or more and 85% by mass or less is particularly preferable. When the content of the carbon element is within the range, both high insulation and good light-shielding property can be achieved at a high level.

Further, assuming that the total number of atoms present in the non-conductive material is 100 atom%, the content of carbon atoms based on the atomic number is preferably 95 atom% or less, and more preferably 93 atom from the viewpoint of eliminating conductivity. % Or less, more preferably 90 atom% or less, particularly preferably 86 atom% or less (for example, 80 atom% or less). Further, the content of carbon atoms based on the number of atoms is preferably 70 atom% or more, more preferably 75 atom% or more, from the viewpoint of better achieving both non-conductive property and light-shielding property. The technique disclosed herein can be preferably carried out, for example, in an embodiment in which the content of carbon atoms is 75 atom% or more and 93 atom% or less. The atomic number-based contents of oxygen atoms and carbon atoms can be grasped by EDX in the same manner as the mass-based contents described above.

The ratio (O / C) of the mass-based content of oxygen element to the mass-based content of carbon element is preferably 0.1 to 0.4 from the viewpoint of achieving both non-conductivity and light-shielding property. , More preferably 0.15 to 0.38, still more preferably 0.2 to 0.35, and particularly preferably 0.25 to 0.35. By setting the content ratio (O / C) to 0.1 or more, the conductivity of the carbon particles can be further reduced, and the content ratio (O / C) is 0.4. By doing the following, both non-conductivity and light-shielding property of carbon particles can be realized at a higher level.

<Volume resistivity>
The volume resistivity of the non-conductive material is not particularly limited as long as the contents of the oxygen element and the carbon element satisfy the above range, but is generally 1 × 10 ⁶ Ω · cm or more, preferably 1 ×. It is 10 ⁷ Ω · cm or more, more preferably 5 × 10 ⁷ Ω · cm or more, further preferably 1 × 10 ⁸ Ω · cm or more, and particularly preferably 5 × 10 ⁸ Ω · cm or more. The upper limit of the volume resistivity of the non-conductive material is not particularly limited, but from the viewpoint of achieving both non-conductivity and light-shielding property, it is preferably 1 × 10 ¹⁰ Ω · cm or less, more preferably 5 × 10 ⁹ Ω ·. It is cm or less, more preferably 1 × 10 ⁹ Ω · cm or less, and particularly preferably 8 × 10 ⁸ Ω · cm or less.

Examples of the suitable non-conductive materials disclosed herein, a content of oxygen element is 9% to 30 wt%, and, what volume resistivity is 1 × 10 ⁷ Ω · cm or more; oxygen element content is 10% to 30% by weight, and is intended a volume resistivity of 2.4 × 10 ⁷ Ω · cm or more; a content of 15% to 30% by weight of oxygen element, And the volume resistivity is 5 × 10 ⁷ Ω · cm or more; the content of oxygen element is 20% by mass to 30% by mass, and the volume resistivity is 5 × 10 ⁸ Ω · cm or more. things; the content of oxygen element is 25 to 30 wt%, and, what volume resistivity is 5.5 × 10 ⁸ Ω · cm or more; and the like.

The non-conductive materials disclosed herein may contain additional constituent elements other than carbon and oxygen elements to the extent that the effects of the present invention are not significantly impaired. As such additional constituent elements, potassium (K), calcium (Ca), sodium (Na), magnesium (Mg), copper (Cu), iron (Fe), zinc (Zn), chromium (Cr), Examples thereof include one or more elements of selenium (Se), manganese (Mn), molybdenum (Mo), iodine (I), phosphorus (P), silicon (Si), and aluminum (Al). These additional constituent elements may preferably be contained in a proportion of 5% by weight or less. It may be a non-conductive material having a content of additional constituent elements of substantially zero.

In a preferred embodiment, the non-conductive material is substantially free of additional constituent elements other than carbon and oxygen elements. As a result, both non-conductive property and light-shielding property can be realized at a higher level. In addition, "the non-conductive material does not substantially contain additional constituent elements" means that, at least intentionally, no additional constituent elements are contained. Therefore, the content of the additional constituent elements in the non-conductive material is 0.2% by mass or less, preferably 0.1% by mass or less, more preferably 0, due to the raw material, the manufacturing method, or the like. The non-conductive material inevitably containing the above-mentioned additional constituent elements of 0.05% by mass or less, particularly preferably 0.001% by mass or less) substantially contains the additional constituent elements referred to here. Can be included in the concept of non-conductive materials.

The shape of the carbon particles constituting the non-conductive material is not particularly limited. Carbon particles having a spherical shape or a shape close to the sphere, or irregularly shaped carbon particles such as a lump, a flaky shape, and a fibrous shape can be preferably used. As such carbon particles, those having an average particle diameter of approximately 0.05 μm to 50 μm (for example, 0.1 μm to 50 μm) are preferable, and for example, those having an average particle diameter of 0.05 μm to 10 μm are more preferable, and typically average. Those having a particle size of 0.05 μm to 1 μm are more preferable. The average particle size of the carbon particles can be measured by, for example, a scanning electron microscope (SEM) or the like.

In the technique disclosed herein, the concept of "carbon particles are amorphous" includes an embodiment in which a crystal phase is present in a part of the carbon particles. A preferred embodiment of the technique disclosed herein is carbon particles having an amorphous phase composed of C and O as a main component and a crystal phase containing at least one element among C, O, H and N. .. Such a crystal phase may be unevenly distributed or precipitated near the surface of the amorphous carbon particles disclosed here, for example. Alternatively, the crystalline phase may be mixed (dispersed) in the amorphous phase.

As any of the non-conductive materials disclosed herein, for example, an organic raw material composed mainly of carbon (C) atoms and oxygen (O) atoms contained in carbon particles constituting the non-conductive material is suitable. It can be produced by selecting the above and firing the organic raw material under appropriate conditions so that at least a part of oxygen atoms in the organic raw material remains in the carbon particles.

The organic raw material used as a raw material for the non-conductive carbon particles is not particularly limited as long as it is composed mainly of carbon (C) and oxygen (O). For example, one or more kinds of cyclic organic compounds having a cyclic molecular skeleton containing a bond (COC) between a carbon (C) atom and an oxygen (O) atom can be appropriately used. It is preferably a cyclic organic compound containing two or more (for example, 2 to 5, preferably 2 or 3) ring structures composed of a cyclic molecular skeleton containing the above COC. Such a cyclic organic compound is preferable because oxygen atoms derived from an organic raw material tend to remain in carbon particles even after firing. In the cyclic organic compound in the technique disclosed herein, it is preferable that the atoms constituting the ring are only carbon (C) atoms and oxygen (O) atoms. The number of atoms constituting the ring of the cyclic organic compound (that is, the total number of C and O) is not particularly limited, but 4 to 20 is appropriate, and 5 to 12 (for example, 5 to 10, typically 5 to 10). It is preferably 5 or 6).

The cyclic organic compound may have a hydrogen atom and an organic group bonded to at least one carbon atom constituting the ring. Examples of the organic group include organic groups having 1 to 12 carbon atoms. Such organic groups include hydroxy groups; hydroxymethyl groups, 1-hydroxyethyl groups, 2-hydroxyethyl groups, 1-hydroxypropyl groups, 2-hydroxypropyl groups, 3-hydroxypropyl groups, 1-hydroxybutyl groups. Hydroxyalkyl groups such as 2,2-hydroxybutyl group, 3-hydroxybutyl group, 4-hydroxybutyl group; methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, sec-butyl group , T-Butyl group, n-Pentyl group, 1-methylbutyl group, 2-methylbutyl group, 3-methylbutyl group, 1-methyl-2-methylpropyl group, 2,2-dimethylpropyl group, hexyl group, heptyl group, Chain alkyl groups such as octyl group, nonyl group and decyl group; and the like can be mentioned. Of these, a hydroxy group; a hydroxymethyl group, a 1-hydroxyethyl group, a 2-hydroxyethyl group, a 1-hydroxypropyl group, a 2-hydroxypropyl group, and a 3-hydroxypropyl group are preferable.

Preferable examples of the organic raw materials disclosed herein include monosaccharides such as glucose, fructose, galactose and mannose, disaccharides such as lactose, sucrose, maltose, trehalose, turanose and cellobiose, raffinose, meregitos and maltotriose. Trisaccharides such as acarbose, tetrasaccharides such as starch, oligosaccharides such as fructose and galactooligosaccharides, polysaccharides such as dextrin, cyclodextrin, cellulose and glucan, sugar alcohols such as xylitol, erythritol and sorbitol, milk protein and soybeans. Examples include polysaccharides such as protein, wheat protein, fructose milk powder, defatted milk powder, wheat flour, starch (amylose, amylopectin), gelatin and purulan. As the starch, for example, potato starch, corn starch, wheat starch, rice starch, sweet potato starch, tapioca starch, green bean starch, sago starch, corn, waxy corn, potato, tapioca and the like can be used. These carbohydrates may be used alone or in combination of two or more.

As described above, the hydrogen atom and the oxygen atom in the organic raw material are volatilized (gasified) by the firing treatment, and the oxygen atom derived from the organic raw material remains in the carbon particles at a ratio of 9% by mass to 30% by mass. By calcining (carbonizing) the organic raw material under various conditions, it is composed of amorphous carbon particles having a carbon element content of at least 70% by mass and an oxygen element content of 9% by mass to 30% by mass. A non-conductive material is obtained. This firing process may be performed in the atmosphere or in an atmosphere richer in oxygen than in the atmosphere, or in an inert gas atmosphere (for example, a nitrogen gas atmosphere). In a preferred embodiment, the firing process is performed in the atmosphere or in an atmosphere richer in oxygen than the atmosphere. By firing in the atmosphere or in an atmosphere richer in oxygen than in the atmosphere, carbon particles having higher insulating properties (that is, a high content of oxygen element) can be realized. In another preferred embodiment, the firing process is performed in an inert gas atmosphere. By firing in an atmosphere of an inert gas, carbon particles having both non-conductive property and light-shielding property at a high level can be realized.

In such a firing treatment, it is preferable to gently fire (that is, incompletely carbonize) the oxygen atoms derived from the organic raw material so that they remain in the carbon particles at a ratio of 9% by mass to 30% by mass. For example, the yield of the non-conductive material obtained after firing is approximately 5% by mass to 30% by mass (for example, 5% by mass to 20% by mass, preferably 6% by mass) with respect to the total mass of the organic raw material before firing. It is preferable to set the firing temperature, firing time, and firing atmosphere under conditions such that% to 18% by mass, more preferably 8% by mass to 15% by mass, and further preferably 10% by mass to 12% by mass). By setting such firing conditions, oxygen atoms derived from organic raw materials can be effectively left in carbon particles at a ratio of 9% by mass to 30% by mass, and the above-mentioned high insulation property and good light-shielding property can be obtained. Amorphous carbon particles that can achieve both of these can be efficiently obtained.

Although not particularly limited, the firing temperature, firing time, and firing atmosphere (for example, in the oxidizing atmosphere) so that oxygen atoms derived from the organic raw material remain in the carbon particles at a ratio of 9% by mass to 30% by mass in the oxidizing atmosphere. Oxygen concentration) may be set appropriately. It may differ depending on the organic raw material used, the firing atmosphere, the constituent conditions of the firing device, and the like, but for example, the firing temperature (maximum ultimate temperature) may be determined within the range of 300 ° C. or higher and 1000 ° C. or lower. From the viewpoint of obtaining carbon particles having higher insulating properties, it is preferable that the firing temperature is set to 300 ° C. to 700 ° C. (for example, 300 ° C. to 500 ° C.). Further, the firing time may be determined within a range of approximately 2 minutes to 60 minutes. The firing time is preferably 2 minutes to 20 minutes from the viewpoint of obtaining carbon particles having higher insulating properties. Such firing conditions can be appropriately changed depending on the organic raw material used, the firing atmosphere, the constituent conditions of the firing device, and the like.

The oxygen-containing carbon (lump) obtained by the above-mentioned firing treatment is preferably cooled and then pulverized by milling or the like to obtain a non-conductive material composed of amorphous carbon particles disclosed here. be able to.

<Use>
As described above, the non-conductive material disclosed herein can stably exhibit non-conductive and light-shielding properties for a long period of time because the carbon particles themselves are insulating substances. Therefore, it can be preferably used as a material (typically a black pigment; a colorant) suitable for applications requiring non-conductive properties and light-shielding properties. In particular, it is suitable as a black pigment for a cover material (for example, a sealing material) of various electronic parts. The electronic component may be, for example, an integrated circuit (IC), a large-scale integrated circuit (LSI), a transistor, or the like. Alternatively, the non-conductive material may be used for coloring a printed circuit board, a shadow mask of a cathode ray tube, a black matrix of a liquid crystal color film, or the like. In such applications, it is particularly meaningful to apply the techniques disclosed herein.

<Paint>
Such a non-conductive material can be used not only alone but also as a composite material in which it is dispersed in another material (resin, solvent, etc.). For example, it may be in the form of a paint (toner or coating agent) in which a non-conductive material is dispersed in a liquid medium.

Examples of the liquid medium for dispersing the conductive material include amide solvents such as N-methyl-2-pyrrolidone (NMP), N, N-dimethylacetamide (DMAC), N, N-dimethylformamide, toluene, xylene, and the like. Hydrocarbon solvents such as cyclohexane, methanol, ethanol, 1-propanol, 2-propanol (isopropyl alcohol), 1-butanol (n-butanol), 2-methyl-1-propanol (isobutanol), 2-butanol (sec) -Butanol), lower alcohol solvents such as 1-methyl-2-propanol (tert-butanol), carbonate solvents such as propylene carbonate, lactone solvents such as γ-butyrolactone and γ-caprolactone, methyl ethyl ketone, methyl isobutyl ketone , Ketone solvent such as cyclohexanone, ester solvent such as ethyl acetate, n-butyl acetate, butyl cellosolve acetate, butyl carbitol acetate, ethyl cellosolve acetate, ethyl carbitol acetate, sulfone solvent such as sulfolane and the like.

Further, the liquid medium may be a liquid resin that is liquid at room temperature. Examples of the liquid resin include epoxy resins. Specific examples of the epoxy resin include phenol novolac type epoxy resin, 0-cresol novolac type epoxy resin, biphenyl type epoxy resin, triphenylmethane type epoxy resin, dicyclopentadiene type epoxy resin, brom-containing epoxy resin, and triphenol methane type. Epoxy resin, alicyclic epoxy resin, heterocyclic epoxy resin, bisphenol A type epoxy resin, bisphenol F type epoxy resin, stillben type epoxy resin, polyfunctional epoxy resin, condensed ring aromatic hydrocarbon modified epoxy resin, naphthalene ring Epoxy resin having is exemplified. These epoxy resins may be used alone or in combination of two or more.

The paints disclosed herein are polyimide resin, polyester resin, acrylic resin, polyethylene resin, polypropylene resin, polycarbonate resin, polystyrene resin, polyvinyl chloride resin, polyamide resin, silicone, as long as the effects of the present invention are not significantly impaired. Resin components such as resins, melamine acrylates, and urethane acrylates, and known additives such as curing accelerators, inorganic fillers, binders, photosensitizers, colorants, and preservatives may be further contained, if necessary. ..

Next, some examples of the present invention will be described, but it is not intended to limit the present invention to those shown in such examples.

In this evaluation test, carbon-based powder materials having different contents of carbon element and oxygen element were prepared. In Example 1, a commercially available acetylene black was used. In Example 2, a commercially available Ketjen black was used. In Example 3, commercially available activated carbon was used. In Example 4, commercially available graphite was used. In Examples 5 to 8, a calcined organic raw material made of the cyclic organic compound was used. However, by devising the firing conditions so that the oxygen atoms derived from the organic raw material remain in the carbon particles, the content of the oxygen element in the carbon particles is different. The yield of such carbon particles was about 12% by mass. For the powder material according to each example, the type of powder used, the content of carbon element (mass%), the content of oxygen element (mass%), the content of carbon atom (atom%), and the content of oxygen atom. The amounts (atom%) are summarized in Table 1. In Example 5, the organic raw material was fired in a nitrogen gas atmosphere, and the content of the oxygen element in the obtained carbon particles was approximately 10% by mass. Therefore, the oxygen atom derived from the organic raw material was the carbon particles. It was confirmed that it remained in.

The carbon element content (mass%), oxygen element content (mass%), carbon atom content (atom%), and oxygen atom content (atom%) of each example are energy dispersive X. It was obtained by line spectroscopy (EDX).

The crystal structure of the powder material of each example was analyzed by a powder X-ray diffraction analyzer (XRD). The X-ray diffraction patterns of Examples 1 to 4 are shown in FIG. Further, the X-ray diffraction patterns of Examples 5 to 8 are shown in FIG. As shown in the X-ray diffraction patterns of FIGS. 1 and 2, Examples 1 to 3 and 5 to 8 (that is, other than graphite of Example 4) show a broad pattern, and all the powder materials are in an amorphous state. It was confirmed that.

In addition, the volume resistivity (volume specific electrical resistance value) was measured for the powder material according to each example. The volume resistivity was measured using the apparatus shown in FIG. First, the powder material of each example was placed in a cylindrical pipe (inner diameter of 10 mm) made of Duracon, sandwiched between electrodes from above and below, and pressurized with a press machine at 1000 kg. After holding such pressurization for 30 seconds, the resistance value between the electrodes was measured at room temperature using a multimeter. The volume resistivity (= measurement resistance value R × contact area S / thickness D) was calculated from the obtained measured resistance value R, the contact area S between the green compact and the electrode, and the thickness D of the green compact. .. In Examples 1 to 5, 7 and 8, 0.5 g of powder material was used for measurement. In Example 6, 0.06 g of powder material was used for measurement. The results are shown in Table 1.

As shown in Table 1, in Example 4 using graphite having a crystal structure, the volume resistivity was 2.41 Ω · cm or less, and it had high conductivity. Further, also in Examples 1 to 3 using an amorphous carbon-based powder material having a carbon element content of 90% by mass or more and an oxygen element content of less than 9% by mass, volume resistivity. The resistivity was 2 Ω · cm or less, and it had high conductivity. On the other hand, in Examples 5 to 8 using an amorphous carbon material having a carbon element content of 70% by mass or more and an oxygen element content of 9% by mass to 30% by mass, the volume resistivity becomes 2.4 × 10 ⁷ Ω · cm or more, as compared to examples 1 to 4, good results in a non-conductive is obtained. From this result, according to the amorphous carbon material having a carbon element content of 70% by mass or more and an oxygen element content of 9% by mass to 30% by mass, the conductivity of the carbon material was eliminated. It was confirmed to get.

Further, comparing Examples 5 to 8, an amorphous carbon material having a carbon element content of 70% by mass to 80% by mass and an oxygen element content of 20% by mass to 30% by mass was used. example 6 was used, the volume resistivity becomes 5.7 × 10 ⁸ Ω · cm or more, as compared with examples 5, 7, 8, better results with a non-conductive is obtained. From this, according to the amorphous carbon material in which the carbon element content is 70% by mass to 80% by mass and the oxygen element content is 20% by mass to 30% by mass, the carbon material is conductive. It was confirmed that can be eliminated at a higher level.

Although the present invention has been described above in terms of preferred embodiments, such a description is not a limitation, and of course, various modifications can be made.

Claims (3)

A non-conductive powder material composed of amorphous non-conductive carbon particles and having a volume resistivity of 1 × 10 ⁶ Ω · cm or more.
The carbon element content determined by energy dispersive X-ray spectroscopy (EDX) is at least 70% by mass , the oxygen element content is 9% to 30% by mass, and the carbon element and oxygen. A non-conductive powder material that is substantially free of additional constituent elements other than elements. A non-electrically conductive powder material that is a volume resistivity made of non-conductive carbon particles of amorphous 5 × 10 ⁸ Ω · cm or more,
At least 70 wt% content of the carbon element to be determined by energy-dispersive X-ray spectroscopy (EDX), and the content is 20% to 30% by mass of oxygen element is, and elemental carbon and A non-conductive powder material that is substantially free of additional constituent elements other than oxygen elements . A coating material comprising the non-conductive powder material according to claim 1 or 2 and a liquid medium.

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