JPH0665604B2 - Particulate glassy carbon and lubricity-imparting agent containing the same - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to particulate glassy carbon and a lubricity imparting agent containing the same. In particular, the present invention relates to fine particle glassy carbon classified so as to have a specific average particle size and particle size distribution, and a lubricity imparting agent utilizing the characteristics of this fine particle glassy carbon.

[Description of Prior Art]

Generally formed in a three-dimensional network structure, carbonization of a cured product of a thermosetting resin having an insoluble and infusible property in an inert atmosphere has excellent gas impermeability, high hardness, and A glassy carbon having an isotropic structure is obtained. This glassy carbon has properties such as light weight, heat resistance, high electrical conductivity, corrosion resistance, thermal conductivity, mechanical strength, and lubricity that ordinary carbon materials have, as well as being homogeneous and used for sliding parts. Since it also has the property of not producing carbon powder, it is expected to be used extensively in various fields including the electronics industry, nuclear industry, and space industry.

On the other hand, conventionally used solid lubricants include powders of molybdenum disulfide, tungsten disulfide, graphite and Teflon. However, these materials are easily affected by contact pressure, sliding speed, etc., and it is difficult to say that they are satisfactory in terms of chemical stability and thermal stability.

For example, in the technique of providing a lubricating layer containing graphite powder on the surface of a thin film magnetic tape used in a magnetic tape device of an information processing device, the graphite powder is destroyed during use,
The destroyed powder adheres to the magnetic head, impairing the recording / reproducing function. Further, molybdenum disulfide and tungsten disulfide are apt to undergo a chemical change due to frictional heat, and Teflon is easily deformed by heat, resulting in deterioration of lubricity. Furthermore, conventionally used liquid lubricants include esters of higher fatty acids, higher fatty acid alcohols, various amide compounds, and the like, and by applying these to a sliding surface or the like, lubricity can be imparted. However, these liquid lubricants are easily lost by volatilization and dissipation, and it is difficult to provide good lubricity over a long period of time.

[Object of the Invention]

The present invention contains a novel glassy carbon powder having a specific average particle size and particle size distribution, and this powder, which is particularly excellent in lubricity, is less susceptible to contact and sliding speed, and is heat resistant. An object is to provide a lubricity imparting agent having excellent properties.

[Characteristics of the Invention]

A feature of the first invention is that it is fine glassy carbon having an average particle size in the range of 0.1 μm to 1.5 μm and a standard deviation of the particle size distribution is within 30% of the average particle size. The characteristic of the above is that it is a lubrication agent containing the characteristics of this glassy carbon fine powder and containing it.

The average particle size referred to here is the following formula (1), (In the formula, is the average particle size, N is the number of particles, and xi is the diameter (measured value) of the i-th particle.) The standard deviation is expressed by the following formula (2), (In the formula, s is the standard deviation, and N and xi have the same meanings as described above.) The standard deviation is within 30% of the average particle size, which means that s and x The relation is the inequality Means to be satisfied.

As a method of measuring the particle size, there is a method of taking a photograph of fine glassy carbon powder through an optical microscope and measuring it,
If a commercially available image analysis device (for example, Luzex 500 manufactured by Nippon Regulator Co., Ltd.) is used, the average particle size and standard deviation can be quickly obtained.

Examples of the raw material of the particulate glassy carbon relating to the present invention include phenol resins, epoxy resins, unsaturated polyester resins, furan resins, urea resins, melamine resins, alkyd resins, xylene resins, and other thermosetting resins, acrylonitrile and divinylbenzene. Examples thereof include coalesce, acrylonitrile / styrene copolymer, and divinylbenzene / styrene copolymer, which can be expected to have a high carbonization yield, and other polymers having a high crosslinking density and a high carbonization yield, and sugar.

As a method for obtaining the fine glassy carbon powder of the present invention,
For example, a glassy carbon mass or plate could be a physical means,
That is, it can be obtained by pulverizing and classifying with a hammer mill, crusher, jet mill, sand mill, ball mill or the like. As still another method, a resin cured product which is a precursor of glassy carbon is pulverized by the above-mentioned physical means, a particle having a desired particle size is taken out by classification, and it is carbonized, There is a method of carbonizing the granular resin by spray drying the raw material resin liquid.

The fine particle glassy carbon of the present invention is excellent not only in lubricity but also in heat resistance, chemical resistance and pressure resistance.

Therefore, a dispersion of fine glassy carbon in a suitable solvent, or a mixture of this fine glassy carbon with a binder in a suitable solvent is a lubricating agent with good performance.

The type and amount of the solvent or binder contained in the lubricity-imparting agent of the present invention may be appropriately selected according to the member to which the lubricity-imparting agent is applied, but generally, as the solvent,
Acetone, methyl ethyl ketone, methyl isoptyl ketone, cyclohexanone and other ketones; methanol, ethanol, propanol, butanol and other alcohols; methyl acetate, ethyl acetate, butyl acetate, ethyl lactate, glycol acetate monoethyl ether, etc. ester; ethers , Glycol dimethyl ether, glycol monoethyl ether, dioxane and other glycol ethers; benzene, toluene, xylene and other tars (aromatic hydrocarbons); methylene chloride, ethylene chloride, carbon tetrachloride, chloroform, ethylene chlorohydrin, di A chlorinated hydrocarbon such as chlorobenzene is used.

Further, as the binder, a conventionally known thermoplastic resin,
A thermosetting resin or a reactive resin or a mixture thereof is used. For example, vinyl chloride-containing copolymer, acrylic acid ester or methacrylic acid ester-containing copolymer,
Examples include urethane elastomers, butadiene-containing copolymers, polyamide resins, polyester resins, and cellulose derivatives. The mixing ratio of the fine particle glassy carbon and the binder is generally 100 parts of the fine particle glassy carbon and 10 parts of the binder.
~ 400 (weight basis).

Further, the lubricity-imparting agent of the present invention is, if necessary, polyethylene wax, microcrystalline wax, wax species such as amide wax, caprylic acid, capric acid,
Lauric acid, myristic acid, palmitic acid, stearic acid, oleic acid, elaidic acid, linoleic acid, linolenic acid, stearic acid and other fatty acids having 12 to 18 carbon atoms (R ₁
COOH, R ₁ is an alkyl group having 11 to 17 carbon atoms); Metal soap consisting of the above-mentioned fatty acid alkali metal (Li, Na, K, etc.) or alkaline earth metal (Mg, Ca, Ba, etc.); lecithin, etc. The dispersant may be included.

In addition, a composite material containing the fine particle glassy carbon, for example, a material obtained by mixing fine particle glassy carbon and a thermosetting resin, followed by curing and further firing, has a surface that is extremely smooth after surface polishing, and the surface is vacant. Since it has few holes, it is useful, for example, as a substrate for a magnetic head or a substrate for a magnetic disk.

The fine particle glassy carbon used in the lubricity imparting agent of the present invention must have an average particle size of 0.1 μm to 1.5 μm, and the standard deviation of the particle size distribution must be within 30% of the average particle size. When the average particle size is less than 0.1 μm, the smoothness of the coating layer is improved, but the glassy powder is often dropped from the coating layer, which is not preferable. If the average particle size exceeds 1.5 μm, abrasion of the sliding member is accelerated, which is not preferable. Even if the average particle size is in the range of 0.1 μm to 1.5 μm, the lubricity becomes insufficient when the standard deviation of the particle size distribution exceeds 30% of the average particle size.

The reason for this is that when the particle sizes are not uniform, the irregularities on the surface coated with the glassy carbon powder are large, but when the particle sizes are uniform, the irregularities on the coated surface are small. It is thought that this is because.

To the lubricity-imparting agent of the present invention, in addition to fine-particle glassy carbon, a hinder, and a solvent, a trace amount of an additive can be added to further improve the lubricity or make the composition convenient for use.

[Explanation by Examples]

Next, the present invention will be described more specifically by way of examples.
The invention is not limited to this embodiment only.

[Manufacture of magnetic tape]

(1) Manufacture of magnetic tape A Mixture of the following composition Co Coated γ-Fe ₂ O ₃ 100 parts by weight Heinder 25 parts by weight Dispersant 1.5 parts by weight Conductive carbon black 5 parts by weight Abrasive 5 parts by weight Lubricant 1 A magnetic paint was obtained by adding a mixed solvent of methyl ethyl ketone and cyclohexanone in a ratio of 1: 1 (weight ratio) to parts by weight and kneading for 24 hours in a ball mill.

Explaining each component of the above blend, Co-deposited γ-Fe ₂ O ₃ has a particle major axis of 1.0 μm and a particle minor axis of 0.2 μm, and the binder is a vinyl chloride-vinyl acetate copolymer (manufactured by Union Carbide Co., USA). VAGH) and a polyurethane resin (N-2304 manufactured by Nippon Polyurethane Industry Co., Ltd.) in a ratio of 1: 1 (weight ratio), the dispersant is lecithin, and the conductive carbon black is CONDUC manufactured by Colombian Carbon Japan Co., Ltd.
TEX SC, abrasive is α-Al ₂ O ₃ containing 60% by weight or more with a particle size of 0.5 to 1.1 μm, and lubricant is butyl myristate.

The magnetic paint obtained by the above method was applied on a polyester film using an applicator of 30 μm, magnetic field orientation was performed, hot air drying was performed, and then the coating film was smoothed by calendering, and further 1 / A magnetic tape for video (hereinafter referred to as magnetic tape A) was manufactured by slitting into a width of 2 inches.

(2) Manufacture of Magnetic Tape B Co was adhered to a 14 μm thick polyethylene terephthalanol film by a so-called oblique vapor deposition method to form a 1000 Å metal ferromagnetic thin film. The oblique evaporation method is a method in which an evaporation beam is incident on the surface of the non-magnetic support from a direction inclined by a predetermined angle, and the magnetic anisotropy of the magnetic layer can be aligned in the predetermined direction. , Its holding power can be increased. This was slit into a 1/2 inch width to produce a magnetic tape (hereinafter referred to as magnetic tape B) [Production of fine powder glassy carbon] (Production Example 1) 100 parts by weight of furfuryl alcohol and 85% 100 parts of phosphoric acid with water
Mix 1.74 parts by weight of acidic catalyst diluted 2 times and mix it with 110
The mixture was kept at 3.5 ° C. for 3.5 hours and at 100 ° C. for 3 hours, and then neutralized with an aqueous sodium hydroxide solution. 10 from the neutralized product by decompression
Water of 0.65% by weight is removed and viscosity is 210 CPS (25 ℃)
Of reddish brown resin was obtained. Furthermore, to 100 parts by weight of this resin, 1.5 parts by weight of a 70% aqueous solution of p-toluenesulfonic acid (PTS) was added, stirred and poured into a mold. 80 ° C for this casting
It was held for about 48 hours to obtain a cured product. Then, this cured product was heated in an electric furnace at a temperature rising rate of 10 ° C./hour under a nitrogen atmosphere at 1000 ° C.
A glassy carbon plate was manufactured by firing to ℃. This plate was roughly crushed with a hammer and then with a jet mill, the particle size was about 10μ.
The particles were pulverized to a size of m to 20 μm and further finely pulverized using a sand mill. This fine powder is subjected to an air classifier, the average particle size is 0.6 μm, and the standard deviation of the particle size distribution is 0.1 μm.
Fine glassy carbon (about 17% of the average particle diameter) was obtained.

(Production Example 2) Belpearl mPC-R (granular powder of phenol resin of Kanebo Co., Ltd.) was placed in a porcelain crucible and placed in an electric furnace under a nitrogen atmosphere to raise the temperature. Temperature rising condition is 2 ℃ up to 300 ℃
/ Min, 1 ° C / min up to 600 ° C, 4 ° C / min up to 1000 ° C, and held for 30 minutes when 1000 ° C was reached. The granular glassy carbon produced in this way was finely pulverized with a sand mill and classified with an air classifier to have an average particle size of 0.9 μm and a standard deviation of the particle size distribution of 0.2 μm (about 22% of the average particle size).
Fine particles of glassy carbon were obtained.

(Production Example 3) In a pressurized reaction vessel equipped with a monomer supply pipe, a catalyst supply pipe, a meter pump, etc., 78 parts by weight of vinylidene chloride, 22 parts by weight of vinyl chloride, 180 parts by weight of water, and 0.22 parts of potassium persulfate in a predetermined order. 30 parts by weight, sodium sulfite 0.11 parts by weight, Perex OTP (Kao Soap Co., Ltd. sulfosuccinate surfactant) 3.58 parts by weight, 69% nitric acid 0.07 parts by weight, and 30
When kept at 8 ° C. for 8 hours, a latex-like product was obtained.
20 parts by weight of urea was added to this product and dried in a spray form to obtain powder particles. Next, the powder particles were placed in a porcelain crucible and placed in an electric furnace. When the electric furnace is heated up to 1200 ° C at a heating rate of 1 ° C / min in a nitrogen atmosphere and kept at this temperature for 30 minutes, the average particle size is 0.5 μm, and the standard deviation of particle size distribution is 0.1 μm ( Fine glassy carbon having an average particle size of 20%) was obtained.

(Production Example 4) 2.1 parts by weight of Gohsenol GM117 (polyvinyl alcohol of Toagosei Co., Ltd.) is dissolved in 100 parts by weight of hot ion-exchanged water, and 250 parts of ion-exchanged water is added to dilute it. Furthermore, 18.2 parts by weight of acrylonitrile, 1 part of divinylbenzene
Ultrasonic dispersion is carried out by adding 8.2 parts by weight and 1.0 part by weight of azobisisobutyronitrile. After completion of dispersion, while stirring
The temperature is raised to 80 ° C over 30 minutes, kept at 80 ° C for 10 hours, and then allowed to cool to room temperature. To this, 7 parts by weight of urea was added and dried in a spray form to obtain a resin powder. This resin powder was placed in a porcelain crucible and placed in an electric furnace. 1 ℃ under nitrogen atmosphere
When the temperature of the electric furnace is raised to 1200 ° C at a temperature rising rate of 1 / min and kept at this temperature for 30 minutes, the average particle size is 1.3 μm and the standard deviation of the particle size distribution is 0.3 μm (about 23% of the average particle size). Particulate glassy carbon was obtained.

(Comparative Production Example 1) The sand mill pulverized fine particle glassy carbon obtained in Production Example 1 was directly sampled without being subjected to a classifier.

This has an average particle size of 0.7 μm and a standard deviation of particle size distribution of 0.5.
It was fine glassy carbon having a particle size of μm (about 71% of the average particle diameter).

(Comparative Production Example 2) The sand mill pulverized fine particle glassy carbon obtained in Production Example 2 was subjected to a classifier to obtain a fine particle glassy carbon having an average particle size of 2.0 μm and a standard deviation of particle size distribution of 0.5 μm (25% of the average particle size). Got

(Example I) 100 parts by weight of the fine glassy carbon obtained in Production Example 1, 400 parts by weight of polyethylene wax (BARRECO 2000 manufactured by Petrolite), and 3000 parts by weight of butanol were placed in a ball mill and stirred for 40 hours. By doing so, a lubricity imparting agent was produced, and the above-mentioned magnetic tape A was immersed in this for 5 seconds and then dried. Furthermore, the surface of the mirror was mirror finished. Using this tape, performance evaluation was performed on the following three items. The results are shown in Table 1.

(1) Lubricity It was evaluated by obtaining the dynamic friction coefficient at 20 ° C using a friction measuring device as shown in the figure. That is, the magnetic tape 1 is fixed by the clamps 2 and 2 ', and a weight 3 having a mass of 50 g is connected to the clamp 2'. Put the chrome-plated rotating cylinder 4 in contact with the magnetic tape 1 and move the rotating cylinder to 100r.
The frictional force between the magnetic tape and the rotary cylinder was read by the strain gauge 5 while rotating at pm, and the dynamic friction coefficient was obtained from this to evaluate the lubricity. The results are shown in Table 1. The first
In the table, relative values are shown with the dynamic friction coefficient obtained in Comparative Example I (described later) as 400. (All of the following examples and comparative examples are also indicated by relative values.) (2) Blocking property of tape Two magnetic tapes were wrapped around each other for 30 minutes,
5 days in a room at 60 ° C and 80% relative humidity (RH) and 5 ° C, 75
% Leave the tape in a room with relative humidity for 5 days, and whether the tape blocks at that time (blocking means that the tape surfaces stick to each other)
Was observed.

(3) Reduction in output of tape Evaluation was performed by measuring the number of times the tape was run when the output decreased by 3 dB using a tape for 30 minutes.

(Example II) The following formulation-Particulate glassy carbon obtained in Production Example 3 100 parts by weight-Urethane binder 30 parts by weight (Nipporan 3022 from Nippon Polyurethane Industry Co., Ltd.)-Methyl ethyl ketone 100 parts by weight-Toluene 100 parts by weight-Cyclohexanone 100 parts by weight • 2 parts by weight of lecithin were put in a ball mill and kneaded for 40 hours, and 100 parts by weight of each of methyl ethyl ketone, toluene and cyclohexanone were added and diluted to obtain a lubricity imparting agent. This was applied onto the surface of the above-mentioned magnetic tape A with an applicator, then dried (the thickness of the lubricity-imparting agent after drying was about 1 μm), and further mirror-finished by a calendar. About this thing, three items were evaluated according to Example I. The results are shown in Table 1.

(Example III) The following mixture; -300 parts by weight of fine glassy carbon obtained in Production Example 2-100 parts by weight of urethane-based binder (Nipporan 2301 of Nippon Polyurethane Industry Co., Ltd.)-2000 parts by weight of ethyl acetate-1000 parts by weight of cyclohexanone- 1 part by weight of stearic acid was placed in a ball mill and kneaded for 40 hours to obtain a lubricity imparting agent. Use a bar coater to apply the magnetic tape B
Was applied to the back surface (which is the surface other than the metal film), and then dried. After drying, three items were evaluated according to Example I for this product.

The results are shown in Table 1.

(Example IV) The following formulation; -Particulate glassy carbon obtained in Production Example 100 100 parts by weight-Urethane binder 200 parts by weight (Nipporan 3004 from Nippon Polyurethane Industry Co., Ltd.)-Nitrocellulose 50 parts by weight (RS from Daicel Chemical Industries) -1/2) ・ Carbon black 100 parts by weight (average particle size 0.5 μm) ・ Ethyl acetate 1300 parts by weight ・ Cyclohexanone 400 parts by weight ・ Calcium stearate 5 parts by weight put in a ball mill and kneaded for 40 hours, and then the following compounding; -Urethane prepolymer 20 parts by weight (Coronate L from Nippon Polyurethane Industry Co., Ltd.)-Ethyl acetate 200 parts by weight-Cyclohexanine 100 parts by weight and kneading for 8 hours in a ball mill to obtain a lubricity imparting agent. This was coated on the back surface of the magnetic tape with a bar coater and then dried. The thickness of the lubricity imparting agent after drying was 3.8 μm. About this thing, three items were evaluated according to Example I. The results are shown in Table 1.

(Comparative Example I) A lubricity-imparting agent was prepared by the method of Example I using the composition obtained by removing the particulate glassy carbon from the composition used in Example III, and the magnetic tape B was treated with the lubricant. Then, with respect to this magnetic tape, three items were evaluated according to Example I. The results are shown in Table 1.

Comparative Example II A lubricity imparting agent was prepared in the same manner as in Example III, except that 100 parts by weight of molybdenum disulfide (average particle size: 0.7 μm) was used instead of the particulate glassy carbon used in Example I. The magnetic tape A was immersed in this for 5 seconds and then dried. Furthermore, the surface of the mirror was mirror finished.
Using this tape, three items were evaluated according to Example I. The results are shown in Table 1.

Comparative Example III Lubricity was imparted by the same method as in Example II except that 100 parts by weight of the particulate glassy carbon obtained in Comparative Production Example 1 was used in place of the particulate glassy carbon used in Example II. An agent was prepared and the magnetic tape A was treated with the agent. With respect to this magnetic tape, three items were evaluated according to Example I. The results are shown in Table 1.

(Comparative Example IV) Lubricity was imparted by the same method as in Example II except that 100 parts by weight of the particulate glassy carbon obtained in Comparative Production Example 2 was used instead of the particulate glassy carbon used in Example II. An agent was prepared and the magnetic tape A was treated with the agent. With respect to this magnetic tape, three items were evaluated according to Example I. The results are shown in Table 1.

(Comparative Example V) Graphite ASSP (manufactured by Nippon Graphite Industry Co., Ltd., average particle size 1 μm) 300 instead of the fine glassy carbon used in Example III
By a method similar to that in Example III except that parts by weight were used,
A lubricity-imparting agent was prepared, and the magnetic tape B was treated with this. With respect to this magnetic tape, three items were evaluated according to Example I. The results are shown in Table 1.

(Example V) The following formulation; -Particulate glassy carbon obtained in Production Example IV 300 parts by weight-Urethane binder 200 parts by weight (Nippon Run 2301) -Ethyl acidate 3000 parts by weight-Stearic acid 1 part by weight Was placed in a ball mill and kneaded for 20 hours to prepare a lubricity-imparting agent, which was spray-applied to the insertion opening of the cash card and dried. The thickness of the lubrication agent after drying is 25 μm. This cash card was repeatedly inserted into the insertion port of the cash dispenser, and the state of the lubrication agent application surface was observed with the naked eye. At that point, abrasion of the coated surface was observed.

(Comparative Example VI) Instead of the particulate glassy carbon used in Example V, a length of 10
Using 300 parts by weight of graph fiber having a diameter of 0.5 μm and a diameter of 0.5 μm, a lubricity-imparting agent was prepared in the same manner as in Example V, and this was used to treat a cash card by the method of Example V.
When a wear test was conducted, wear was recognized at the number of insertions of 60,000 times.

(Example VI) 40% by volume of the glassy carbon fine particles obtained in Production Example 2 and 60% by volume of a thermosetting resin such as furfuryl alcohol / formalin / phenol were mixed and then cured, and then carbonized to form glass. A composite material aggregate containing a carbon material was obtained. This aggregate was cut into a shape having a diameter of 130 mm and a thickness of 2 mm, and the surface thereof was polished with alumina powder having a particle size of 1 μm, and finally polished with alumina powder having a particle size of 0.25 μm to give a mirror finish. Then, this was immersed in Freon at about 20 ° C. for 10 minutes for surface cleaning to obtain a magnetic disk substrate. In order to investigate the surface smoothness of this substrate, the surface roughness was measured using a surface roughness meter (Tokyo Seimitsu Co., Ltd. Surfcom).

Further, the surface thereof was observed with an optical microscope, and the number of holes having a diameter of 2 μm or more existing in a certain fixed visual field was examined.

The results are shown in Table 2.

(Comparative Example VII) Instead of the fine particle glassy carbon used in Example VI, the fine particle glassy carbon obtained in Comparative Production Example 1 was used to prepare a disk substrate according to the method of Example VI, The roughness and the number of holes having a diameter of 2 μm or more were examined. The results are shown in Table 2.

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Claims (2)

[Claims] 1. Fine glassy carbon having an average particle size in the range of 0.1 μm to 1.5 μm and a standard deviation of the particle size distribution within 30% of the average particle size. 2. A fine particle glassy carbon having an average particle size in the range of 0.1 μm to 1.5 μm and a standard deviation of particle size distribution within 30% of the average particle size as a main component in a binder and / or a solvent. Dispersed lubricant agent.