JP2010037412A - Method for producing sliding member - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing a sliding member excellent in strength, heat resistance, low friction, and low abrasion. <P>SOLUTION: The method for producing a sliding member comprises simultaneously performing a step of mixing bacteria cellulose in the form of a water-containing gel as a reinforcing fiber with a liquid phenolic resin dissolved in a hydrophilic organic solvent to dry the water content and a step of impregnating the bacteria cellulose with the resin, thereafter drying and curing this mixture to make an FRP molded product having a desired shape, and then firing this FRP molded product in an inert atmosphere to carbonize the bacteria cellulose and the phenolic resin, thereby producing a sliding member having a volume content ratio of carbon fibers obtained by carbonizing the bacterial cellulose of 30-70 vol.%. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

The present invention relates to a method for producing a sliding member using carbon fibers carbonized from bacterial cellulose as reinforcing fibers and carbonized phenol resin as a matrix.

In general, ceramic materials have characteristics that enable industrial application in various fields. For example, in the mechanical industry field, ceramic materials have been expected to be used in harsh tribological environments, and in particular, are expected to be used as sliding materials without lubrication. Among them, carbon fiber reinforced carbon materials are used as sliding materials used without lubrication because they have superior mechanical properties such as fracture strength and fracture toughness compared to other industrial ceramics. .

Conventionally, when producing a carbon fiber reinforced carbon material, FRP is formed using a carbon fiber and a thermosetting resin having a high carbonization yield such as a phenol resin, and then fired at a high temperature of about 500 to 1500 ° C. Combined to produce a precursor. At this time, the resin used as a matrix is carbonized and the volume shrinks, and there is a problem that voids are generated and mechanical properties are deteriorated.

For this reason, a method (Patent Document 1) has been proposed in which mechanical properties are improved by impregnating with a pitch powder or the like to make it dense. However, in this method, since expensive carbon fibers are used and it is necessary to repeat mixing and carbonization steps of pitch powder and the like many times, there is a problem that the manufacturing period is long and the manufacturing cost is high.

In addition, bacterial cellulose produced in the acetic acid production process has been researched and developed as an industrial material due to its potential performance (Patent Document 2), but its water content is as high as 80% by weight or more. There is no usage and most are disposed of as industrial waste. In addition, when making FRP using bacterial cellulose, since the water content is high, it takes time for the dehydration process, and in order to mix it with the resin after dehydration, dry bacterial cellulose must be crushed, and this process is also manufactured. The cost was high and it was one of the factors that were not industrialized.
JP-A-9-268082 JP2003-82535A

Under the circumstances, the present invention aims to develop a carbon fiber reinforced carbon material that can be used without lubrication. As a result of intensive research, the present invention contains a large amount of water disposed as waste. The bacterial cellulose is directly impregnated with a phenol resin to simplify the process by simultaneously performing the moisture drying process and the resin impregnation process, and is lightweight with low friction and low wear under no lubrication. The present invention provides a manufacturing method of a sliding member having high strength and high hardness.

According to a first aspect of the present invention, there is provided a method for producing a sliding member comprising a gelled bacterial cellulose containing water as a reinforcing fiber, and a liquid phenol resin dissolved in a hydrophilic organic solvent mixed therein to dry the moisture. After simultaneously performing the process and the resin impregnation process, the mixture is dried and cured to produce an FRP molded body having a desired shape, and then the FRP molded body is baked in an inert atmosphere to produce bacterial cellulose and phenol. A sliding member in which the volume content of carbon fibers obtained by carbonizing a resin and carbonizing bacterial cellulose is 30 to 70% by volume is manufactured.

The manufacturing method of the sliding member according to claim 2 of the present invention is the method according to claim 1, wherein the moisture content of the gelled bacterial cellulose is 80% by weight or more, and the content of the organic solvent of the liquid phenol resin is 40% by weight. As described above, the mixing ratio of the liquid phenol resin to be mixed with the gelled bacterial cellulose is 5 to 40% by weight.

According to the method for producing a sliding member according to claim 1 of the present invention, FRP composed of bacterial cellulose and a phenol resin is carbonized, a fine fibrous carbon compound derived from bacterial cellulose is used as a reinforcing fiber, and is derived from phenol. By strengthening the glassy carbon compound as a matrix, the fracture toughness value of the material itself is improved, wear due to brittle fracture is suppressed, and it has sufficient low friction and low wear even under no lubrication. A sliding member can be manufactured.

In addition, by directly impregnating a bacterial cellulose gel containing moisture of 80% by weight or more with a phenol resin, it becomes possible to combine the moisture drying step and the resin impregnation step into one, and omit the steps. Cost can be reduced.

According to the method for producing a sliding member according to claim 2, the moisture content of the gel-like bacterial cellulose is 80% by weight or more, and the bacterial cellulose produced in the acetic acid production process can be used as it is. Further, by setting the content of the organic solvent of the liquid phenol resin to 40% by weight or more, the bacterial phenol is sufficiently impregnated with the liquid phenol resin. Further, by adjusting the mixing ratio of the liquid phenol resin to be mixed with bacterial cellulose to 5 to 40% by weight, the moisture drying process is promoted, and the carbonized fine carbon fibers dispersed in the glassy carbon compound are slid A member can be obtained.

First, gelled bacterial cellulose is used as a reinforcing fiber, and this is mixed with a liquid phenolic resin dissolved in a hydrophilic organic solvent. The gelatinous bacterial cellulose produced in the acetic acid production process generally has a water content of 80% by weight or more. As the phenol resin, a liquid resin dissolved in a hydrophilic organic solvent so as to be easily mixed with bacterial cellulose is used. In this case, as the organic solvent, for example, alcohols, phenols, acetones, and ethers are used. Further, by setting the content of the organic solvent of the liquid phenol resin to 40% by weight or more, the viscosity is low, and it is easy to mix and impregnate with bacterial cellulose.

When a liquid phenol resin dissolved in a hydrophilic organic solvent is mixed with gelled bacterial cellulose, the hydrophilic organic solvent dehydrates the moisture contained in the bacterial cellulose, and the bacterial cellulose is impregnated with the phenol resin. A moisture drying step and a resin impregnation step are simultaneously performed to produce a prepreg. In this case, any one or several other materials such as carbon, wood, inorganic mineral, etc. may be added as the third component.

In this case, the mixing ratio of the liquid phenol resin to be mixed with the gelled bacterial cellulose is preferably in the range of 5 to 40% by weight. In this case, the addition of less than 5% by weight cannot sufficiently solidify the bacterial celluloses, and when carbonized into carbon fibers, the amount of wear of the abrasive increases, and if added over 40% by weight This is because the proportion of carbon fibers produced from bacterial cellulose as a reinforcing material is reduced, and the progress of cracks cannot be prevented, resulting in an increased amount of wear.

When a prepreg is produced by mixing phenolic resin with water-containing bacterial cellulose and simultaneously drying it, it may be dried by any method such as natural drying, forced drying using an oven, or reduced pressure drying using a vacuum pump. .

Next, the prepared prepreg is put into a predetermined mold, and an FRP is prepared through a pressurizing and heating process. At this time, gas is generated due to the dehydration condensation reaction of the phenol resin. To remove this reaction gas, it is better to carry out the degassing process several times, but if the generated amount is small, the degassing process is omitted. May be.

Lastly, the FRP molded into a predetermined shape is sintered in a temperature range of 500 to 1500 degrees under an inert atmosphere, whereby fine carbon fibers with a nano-order diameter are dispersed in glassy carbon. A member can be obtained. In this case, the sliding member has sufficient low friction and low wear of 0.25 or less even under no lubrication by setting the volume content of carbon fiber carbonized with bacterial cellulose to 30 to 70% by volume. Is obtained.

In this case, if the volume content of the carbon fiber is less than 30% by volume, the ratio of the carbon fiber is reduced, and sufficient low friction and low wear cannot be obtained. Because it will increase.

Example 1
A liquid phenol resin containing 50% by weight of alcohol was mixed with gelled bacterial cellulose having a water content of 90% by weight at a mixing ratio of 20% by weight, and a moisture drying step and a resin impregnation step were simultaneously performed. Next, this mixture was naturally dried and cured to prepare a prepreg. Next, this prepreg was put in a mold, and FRP was prepared by pressurizing and heating at a pressure of 6 kg / cm ² and a temperature of 160 ° C. for 30 minutes. Thereafter, it was heated to 1000 ° C. for 60 minutes in an inert atmosphere, fired and carbonized to produce a sliding member (N 2 _O 1). The sliding member had a carbon fiber content of 40% by volume and the mechanical properties as shown in Table 1. Table 2 shows the results of comparison of specific wear with the sliding member of the present invention, silicon nitride ceramics, and diamond-like carbon.

From the results in the above table, it was confirmed that they had high mechanical properties and the specific wear amount was superior to conventional ceramics.

(Example 2)
In Example 1, after mixing the gel-like bacterial cellulose having a water content of 90% by weight with a liquid phenol resin containing 50% by weight of alcohol at different mixing ratios, this mixture was subjected to the same conditions as in Example 1. A prepreg was prepared by drying and curing, and this was pressurized and heated to prepare FRP. Then, it heated and baked and carbonized in inert atmosphere, and the sliding member ( _N2O3, 3) was manufactured. For comparison, gelled bacterial cellulose mixed with a liquid phenol resin with a different mixing ratio is also fired and carbonized to produce a sliding member (N _O 4,5). The mixing ratio, carbon fiber content, dynamic friction coefficient, and specific wear were measured, and the results are shown in Table 3.

From the results in the above table, it was confirmed that the dynamic friction coefficient was low and the specific wear amount was small when the carbon fiber content was in the range of 30 to 70% by volume.

Claims (2)

After mixing water-containing gel-like bacterial cellulose with reinforcing fibers and mixing it with a liquid phenol resin dissolved in a hydrophilic organic solvent, the moisture drying step and the resin impregnation step are performed simultaneously, and then the mixture is dried.・ Curing to create a desired shape FRP molded body, and then firing this FRP molded body in an inert atmosphere to carbonize bacterial cellulose and phenolic resin, containing the volume of carbon fiber carbonized bacterial cellulose A method for producing a sliding member, comprising producing a sliding member having a rate of 30 to 70% by volume. The water content of the gel-like bacterial cellulose is 80% by weight or more, the content of the organic solvent of the liquid phenol resin is 40% by weight or more, and the mixing ratio of the liquid phenol resin mixed with the gel-like bacterial cellulose is 5 to 5%. The method for manufacturing a sliding member according to claim 1, wherein the content is 40% by weight.