JPS6215119B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a modified composition of fluorinated graphite useful as a solid lubricant, a battery active material, etc., and more particularly to fluorinated graphite whose surface is coated with a graft-polymerized polymer and a method for producing the same. It is. Graphite fluoride is a white to gray solid powder obtained by reacting carbon or graphite with fluorine.
(CF) _o or (C ₂ F) _o is known, and it has unique lubricity, water and oil repellency, and excellent chemical resistance, so it is used as a solid lubricant and battery active agent. It is widely used as a substance. However, due to its low surface energy, graphite fluoride has strong water repellency, does not disperse in water, has poor compatibility with resins, and has poor moldability, so there are problems when handling it in various forms. There were many. Therefore, it is usually necessary to mold the material using an appropriate binder or to perform a treatment to improve dispersibility. For example, when used as a solid lubricant, it is ideal that the graphite fluoride powder itself forms a continuous adhesive film on the area where it is used, but as mentioned above, graphite fluoride has no wettability with water. Not shown, the contact angle with water is 145° in the case of (CF) _o ,
That of PTFE (tetrafluoroethylene resin) is 100 to 110
Since it is very large compared to the average size of 100.degree., it is almost impossible to disperse it as it is even if water is used as a carrier. Therefore, previously
In the invention described in this publication, a method using a dispersant such as colloidal silica is used, and in the invention described in JP-A-49-116462, the surface is coated with a caking substance or a caking substance and a surfactant. Fluorinated graphite, which is coated with graphite, has been proposed and has shown considerable effectiveness, but the reality is that it is still not sufficient and does not provide a complete solution. In other words, Tokko Akira
49-19750 uses a dispersant such as colloidal silica to improve dispersibility, but due to its structure, when used as a molded article, there is an upper limit to the content of graphite fluoride. However, it can only be contained in an amount of about 60% by weight at most, and the various properties of graphite fluoride derived from its surface energy cannot be effectively utilized. Furthermore, in the method disclosed in JP-A-49-116462, a caking substance such as wax is coated on the surface of graphite fluoride particles by mere physical forces such as so-called adsorption and adhesion. In the usage mode, the coated state is not always stable, and furthermore, it has the disadvantage that uniform coating is difficult. Moreover,
In the case of such a method, it is almost impossible to minimize the amount of caking substance on the fluorinated graphite and to uniformly coat the fluorinated graphite in order to fully exhibit its characteristics. . Also,
As an example of a molded product mainly composed of graphite fluoride, it is known that in the method of manufacturing electrodes for primary batteries, a mixture with PTFE is pressure molded. Normally, an aqueous PTFE dispersion obtained by emulsion polymerization of TFE (tetrafluoroethylene) is used, but since graphite fluoride has extremely high water repellency, graphite fluoride is pre-mixed with an organic material with a strong affinity for water. It is necessary to add it by suspending it in a solvent, and in order to sufficiently wet the fluorinated graphite,
A large amount of organic solvent is required, and the PTFE particles coagulate to form a large coagulum, making it impossible to obtain a uniform powder mixture. Furthermore, this large coagulum is highly adhesive and difficult to crush, and if compression molded as it is, pressure is not applied uniformly, which tends to cause internal distortion, making it impossible to obtain a good molded product. The purpose of the present invention is to solve the above-mentioned drawbacks, and to make graphite fluoride exhibit extremely good dispersibility in various carriers and at the same time maximize the characteristics of graphite fluoride. As a result of intensive research, it was discovered that this object could be achieved by microcapsulating fluorinated graphite powder by graft polymerizing a vinyl monomer onto the surface thereof, and the present invention was completed. That is, the present invention is a polymer-coated fluorinated graphite whose surface is graft-bonded with a vinyl resin, and a method for producing the same. and a vinyl monomer capable of radical polymerization or radical copolymerization, polymerization is performed in the presence of a water-soluble polymerization initiator, and the graphite fluoride is coated with a polymer graft-bonded to the graphite fluoride. This is a method for producing polymer-coated fluorinated graphite. What is the graphite fluoride used in the present invention (CF) _o?
(C ₂ F) In addition to those represented by _o , it also includes mixtures thereof in any proportion. The graphite fluoride of the present invention is graft-bonded with a vinyl resin, and the bond is different from mere adsorption or adhesion, and is bonded to the graphite fluoride surface in a form that is so strong that it cannot be separated by solvent extraction. This provides uniform coverage.
The resin content can take any value, but in order to have good dispersibility, it needs to be at least 0.5% by weight, and there is no upper limit, but in order to exhibit the physical properties of graphite fluoride, it should be 50% by weight. It can be said that it is preferable that the Therefore, even with a small amount of resin, the dispersibility of various carriers is good, and when molded, it can be easily molded under heat and pressure, has extremely good workability, and has high strength. Since the graphite fluoride of the present invention is coated uniformly and firmly even with a small amount of resin, the characteristics of the graphite fluoride can be maximized, and its uses are further expanded. For example, it can be suitably used for plastic fillers, additives for lubricating oils, greases, etc., bearings with lubricating performance, packings, molded bodies for electrodes, and the like. In the present invention, the vinyl resin coating is not limited to a complete coating of graphite fluoride, but also includes one in which the surface of graphite fluoride is partially exposed. The organic solvent used in the method of the present invention may be any solvent as long as it is soluble in water, such as methyl alcohol,
Various alcohols such as ethyl alcohol, ketones such as acetone, ethers, amines, etc. are used, and as the surfactant, any one of anionic, cationic, and nonionic surfactants may be used, and a mixture of It may be a system. On the other hand, the vinyl monomer for forming the polymer coating the fluorinated graphite may be one that can be radically polymerized or radically copolymerized, such as acrylic acid, methacrylic acid, acrylates, methacrylates, etc. Monomers having a vinyl group such as , acrylic ester, methacrylic ester, acrylonitrile, N-methylolacrylamide, vinyl chloride, vinyl acetate, styrene, and divinylbenzene are used. Water-soluble polymerization initiators include sulfur dioxide, sulfite aqueous solution, bisulfite solution, potassium persulfate,
Azobiscyanovaleric acid, V-50 (2,2'-azobis-(2-amidinopropane)-dihydrochloride, manufactured by Wako Pure Chemical Industries, Ltd.), and the like are used. To carry out the present invention preferably, 1 to 100 parts by weight of an organic solvent or 1 to 10 parts by weight of a surfactant is added to 100 parts by weight of water.
Add 50 parts by weight, 1 to 100 parts by weight of fluorinated graphite, and 0.1 to 100 parts by weight of vinyl monomer, stir and disperse well, and add a polymerization initiator to the suspension thus obtained. , stir well. A sufficient amount of the polymerization initiator is in the range of 0.01 to 20% by weight based on the vinyl monomer. The polymerization reaction of the present invention can be carried out at room temperature, but if it is desired to shorten the polymerization time, it may be heated to about 70°C. According to the present invention, a high polymerization rate can be obtained in a short polymerization time of about 1 to 5 hours. After the polymerization reaction is completed, the slurry of fluorinated graphite is separated, thoroughly washed with water, and the residue is dried. The polymer coating composition of fluorinated graphite obtained by the method of the present invention as described above can be coated with any amount of resin, and the reaction conditions can be easily controlled. In this way, in the present invention, graphite fluoride can be microencapsulated using a very small amount of resin, and the resulting product can be molded freely. It is possible to form something close to a continuous adhesive film (layer) by itself, and even when dispersed in other materials, the dispersibility is extremely good because the surrounding area is covered with a compatible affinity polymer coating. Therefore, the performance can be effectively utilized, and the effects of graphite fluoride, which have been conventionally used, can be achieved in various applications beyond those of graphite fluoride alone. Next, examples of typical uses are listed. (1) Molded objects obtained by making composite materials with synthetic rubber, natural rubber, synthetic resin, glass fiber, ceramics, carbon resin, asphalt, tar-pitch graphite, etc. can be used as self-lubricating sliding parts, packing, and gaskets. Used for sealing materials, fibers, etc. The polymer-coated graphite fluoride of the present invention is firmly bonded to the base material and can form a stable lubricating film on the sliding surface.
Can withstand high PV values (product of pressure and velocity) with less wear. Examples of the above synthetic rubbers include styrene rubber, butadiene rubber, chloroprene rubber, butyl rubber, nitrile rubber, ethylene propylene rubber, Hypalon, acrylic rubber, urethane rubber, fluorine rubber, silicone rubber, thiokol rubber, and ethylene acetate rubber. Phenol resin, urea resin, melamine resin, aniline resin, unsaturated polyester, diallyl phthalate, epoxy resin, alkyd resin, polyimide, silicone resin, polyethylene, polypropylene, polystyrene, polymethyl methacrylate, polyacrylonitrile, polyvinyl butyral, polyamide, ABS , polycarbonate, polyacetal, polyethylene terephthalate, polyphenylene oxide, polysulfone, polyphenylene sulfide, polyurethane, ionomer resin, fluororesin, cellulose plastic, and the like. (2) Added to grease, lubricating oil, gear oil, spindle oil, refrigeration oil, dynamo oil, turbine oil, etc.
Machine oil, cylinder oil, aviation piston engine lubricating oil, marine engine oil, fiber grease, cup grease, graphite grease,
Used for automotive bearing grease, rolling bearing grease, etc. The above lubricating oils include polyolefins, glycols, carboxylic acid esters, phosphoric esters, silicones, perfluorocarbon acids, chlorinated aromatics, etc., and the greases include calcium soap grease, sodium soap grease, and aluminum soap grease. Examples include mixed soap grease, barium soap grease, calcium complex grease, barium complex grease, and non-soap grease using a thickener other than soap, such as bentone or fine silica. (3) As a dry lubricating film, the polymer-coated fluorinated graphite of the present invention alone or in combination with other organic or inorganic binders is coated on sliding parts to form a dry lubricating film, which improves lifelong lubrication, initial break-in, and separation. Used for molds. (4) Used, for example, in the form of a spray, as a lubricating mold release agent for sintered alloys, plastic molded products, rubber molded products, etc. (5) Used by mixing and adding to cutting oil, press oil, rolling oil, and grinding oil for lubrication during metal processing, cutting, rolling, drawing, pressing, polishing, etc. In addition to the above-mentioned uses as a lubricant and a mold release agent, the graphite fluoride can be used excellently in various other uses for which graphite fluoride has been conventionally used. Next, the present invention will be explained in more detail with reference to Examples. Example 1 A 1-capacity three-necked flask was immersed in a constant temperature water bath maintained at 60°C, and 200ml of ethyl alcohol and water were added.
280 ml of fluorinated graphite (CF) (100 g of fluorinated graphite (CF) (after 300 mesh passes after being crushed in a jet mill, the micrograph is shown in Figure 1)) was added, and while stirring and mixing, 20 ml of a 6% sulfite aqueous solution was added. Polymerization was carried out. The pH at this time is approximately 2. 4 hours after adding the sulfite aqueous solution,
The reaction product was separated, thoroughly washed with water, and dried under vacuum at 80°C. The weight of this product was 117.8 g, and as is clear from the micrograph shown in FIG. 2, the presence of fluorinated graphite or polymer alone was not observed, and the fluorinated graphite was well covered with the polymer. Also,
After extracting this material with benzene for 48 hours, the infrared absorption spectra of the extract and the benzene-insoluble material were measured, and the patterns shown in FIGS. 5 and 6 were obtained, respectively. This confirmed that the extract was a homopolymer of polymethyl methacrylate, and that the benzene-insoluble portion also matched the spectrum of polymethyl methacrylate. From these results, it was confirmed that polymethyl methacrylate was graft-bonded to the surface of graphite fluoride. Furthermore, it was confirmed that the content of polymethyl methacrylate was 15.1% by weight based on the weight reduction by thermogravimetric analysis TGA (hereinafter, in the Examples, the grafting and polymer (The content rate was confirmed.) Example 2 A 1-capacity three-necked flask was immersed in a constant temperature water bath maintained at 60°C, and 150ml of ethyl alcohol and water were added.
Add 330 ml of graphite fluoride (C ₂ F) _, 100 g of fluorinated graphite (C 2 F) (freshly crushed in a diet mill, 250 mesh passes, shown in the micrograph in Figure 3), and 30 g of methyl methacrylate, and while stirring, add 20 ml of 9% sulfite aqueous solution. and polymerization was carried out. The pH at this time is approximately 2.
Three hours after the addition of the sulfite aqueous solution, the reaction product was separated, thoroughly washed with water, and then vacuum dried at 80°C. A microscopic photograph of this product is shown in FIG. In this way, 124.7 g of a dry product containing 19.8% by weight of polymethyl methacrylate was obtained. Example 3 Immerse a 1 volume three-necked flask in a constant temperature water bath at 60°C, add 150ml of ethyl alcohol, 330ml of water, 100g of graphite fluoride (CF), _and 30g of methyl acrylate, and add 6% sulfite while stirring. Polymerization was carried out by adding 20 ml of an aqueous solution. Three hours after the addition of the sulfite aqueous solution, the reaction product was separated, thoroughly washed with water, and then vacuum dried at 70°C. In this way, 121.2 g of a dry product containing 17.5% by weight of polymethyl acrylate was obtained. Example 4 A 1-capacity three-necked flask was immersed in a constant temperature water bath at 60°C, and 200ml of methyl alcohol, 285ml of water, 100g of graphite fluoride (C ₂ F), _and 20g of methyl acrylate were added.
Add 15ml of 6% sulfite aqueous solution while stirring.
was added to carry out polymerization. Four hours after the addition of the sulfite aqueous solution, the reaction product was separated, thoroughly washed with water, and then vacuum dried at 70°C. In this way, the content of polymethyl acrylate is 10.8
111.8 g of dry product by weight was obtained. Example 5 A 1-capacity three-neck flask was immersed in a constant temperature water bath at 50°C, and 10 ml of polyoxyethylene alkyl ether, a nonionic surfactant, 470 ml of water, 100 g of graphite fluoride (CF), _and methyl methacrylate were added. 30g
Add 20ml of 6% sulfite aqueous solution while stirring.
was added to carry out polymerization. 4 hours after adding the sulfite aqueous solution, separate the reaction product,
After thoroughly washing with water, it was vacuum dried at 70°C. In this way, the content of polymethyl methacrylate is 17.4
120.1 g of dry product by weight was obtained. Example 6 Immerse a 1-capacity three-necked flask in a thermostatic water bath at 60°C, add 200 ml of ethyl alcohol, 280 ml of water, 100 g of fluorinated graphite (CF), _and 30 g of acrylonitrile while stirring. 10% of pharmaceutical products)
20 ml of aqueous solution was added to carry out polymerization. Three hours after the addition of the V-50 aqueous solution, the reaction product was separated, thoroughly washed with water, and then vacuum dried at 80°C. In this way, 123.9 g of a dry product with a polyacrylonitrile content of 19.3% by weight was obtained. Example 7 A 1-capacity three-necked flask was immersed in a constant temperature water bath at 60°C, and 200 ml of ethyl alcohol, 280 ml of water, 100 g of graphite fluoride (CF), _and 15 ml of methyl methacrylate were added.
While stirring, 20 ml of a 6% sulfite aqueous solution was added to carry out polymerization. Three hours after the addition of the sulfite aqueous solution, the reaction product was separated, thoroughly washed with water, and then vacuum dried at 80°C. In this way, 122.5 g of a dry product with a copolymer content of 18.8% by weight was obtained. Example 8 Acetone in a 1 volume three neck flask at room temperature
200 ml, 280 ml of water, 100 g of graphite fluoride (CF), _and 10 g of methyl methacrylate were added, and while stirring and mixing, 10 ml of a 6% sulfite aqueous solution was added to carry out polymerization.
Five hours after the addition of the sulfite aqueous solution, the reaction product was separated, thoroughly washed with water, and then vacuum-dried at 70°C. In this way, 105 g of a dry product containing 4.8% by weight of polymethyl methacrylate was obtained. Example 9 Polymerization was carried out under the same conditions as in Example 8 except that the amount of methyl methacrylate added was 5 g and the polymerization time was 3 hours, resulting in 101.2 g of a dry product with a polymethyl methacrylate content of 1.2% by weight. I got it. Example 10, Comparative Example 1 Polymer-coated fluorinated graphite obtained in Example 8 (PMMA adhesion amount: 4.8% by weight) and untreated fluorinated graphite (Comparative Example 1) were each added at 1% to turbine oil #40 at room temperature. Add at the ratio of
Immediately after mixing at 10,000 rpm for 10 minutes, and after holding in a centrifuge (3,000 rpm) for 5 minutes, the particle sedimentation properties of each were compared. As a result, the fluorinated graphite of Comparative Example 1 almost completely settled after 15 minutes. On the other hand, although some sedimentation was observed in the fluorinated graphite of Example 8 even after 60 minutes had passed, it remained almost well dispersed. Example 11, Comparative Examples 2 and 3 Example 1 was applied to 10 g of polymer-coated fluorinated graphite obtained in Examples 1, 2, 4, 6, 7, 8, and 9 (Example 11) and untreated fluorinated graphite, respectively. ,2,4,
10g to have the same resin content as 6, 7, 8, and 9.
were dry mixed (Comparative Example 2), and polymethyl methacrylate was added to make 10 g (Comparative Example 3) at a ratio of 1:1 to untreated fluorinated graphite. Table 1 shows the results of evaluating the moldability, bending strength, and dispersion state of graphite fluoride. Molding conditions are 180
Compression molding at 250Kg/cm ² for 10 minutes at ℃. In Comparative Example 2, either cannot be molded or
Otherwise, strength measurement could not be performed due to poor molding.

[Table] FIGS. 7 and 8 show microscopic photographs of the fractured surfaces of the molded body molded using the polymer-coated graphite fluoride of Example 1 and the compression molded body of Comparative Example 3. As is clear from this, it can be confirmed that the samples of Examples are uniformly dispersed, whereas the samples of Comparative Example 3 have extremely poor dispersibility. Example 12 Using the polymer-coated fluorinated graphite of Example 1,
A 10 x 30 x 2 mm test piece was cut out from the polymer-coated fluorinated graphite molded body compression-molded by the method of Example 11, and the contact angle was measured on the compressed surface under the following conditions. The results are shown in Table 2. () Measurement after washing the measurement surface of the test piece with ethanol. () Place the test piece in a sealed glass container filled with about 50 c.c. of water and shake it at a rate of about 200 times per minute for 1 hour. , then measurement after cleaning with ethanol, () Lightly sand the measurement surface with No. 800 emery sandpaper and measurement after cleaning with ethanol, () Measurement after treating the specimen in () under the conditions in () Comparative example 4 Comparative example 3 The contact angle of the molded article was measured in the same manner as in Example 12, and the results are shown in Table 2.

[Table] * The molding surface is not smooth and has considerable unevenness.
In Example 12, the measurement conditions are as follows:
The contact angle is larger than that of the fluorinated graphite, which is thought to be because the resin layer on the back surface partially peeled off as a result of surface polishing, exposing the graphite fluoride. Furthermore, in Comparative Example 4, it is thought that deviation of the fluorinated graphite caused a decrease in the contact angle.

[Brief explanation of the drawing]

1 and 2 are micrographs of untreated (CF) _o and polymer coated (CF) _o of Example 1;
Figures 3 and 4 show micrographs of the untreated (C ₂ F) _o and polymer coated (C ₂ F) _o of Example 2. 5 and 6 show infrared absorption spectral patterns of the extract and benzene-insoluble material obtained by the benzene extraction treatment of the product in Example 1. FIG. 7 and FIG. 8 show microscopic photographs of the fractured surfaces of the molded bodies of Example 11 and Comparative Example 3, respectively.

Claims (1)

[Claims] 1. Polymer-coated fluorinated graphite whose surface is graft-bonded with a vinyl resin. 2. The polymer-coated fluorinated graphite according to claim 1, which is formed by pressure molding. 3 In a water-organic solvent mixed system or water-surfactant mixed system, fluorinated graphite and a vinyl monomer capable of radical polymerization or radical copolymerization are dispersed, and in the presence of a water-soluble polymerization initiator. A method for producing polymer-coated graphite fluoride, which comprises polymerizing the graphite fluoride and coating the graphite fluoride with a polymer graft-bonded to the graphite fluoride.