JPS6320952B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a string-like body for friction materials that has extremely excellent properties as a fiber material for friction materials used in automobiles, industrial machines, etc. The inorganic fiber material that has traditionally been widely used as a friction material for clutch facings, brake linings, disk pads, etc. is asbestos fiber, but recently, asbestos fiber resources have decreased and problems with asbestos pollution have arisen, and asbestos There has been an increasing demand for friction materials that do not use fibers. Under these circumstances, studies are currently being actively conducted on the use of other inorganic fibers such as glass fibers as fiber materials for friction materials in place of asbestos fibers, but this has not yet been put into practical use. The current situation is that this is not the case. This is because, compared to asbestos fibers, inorganic fibers other than asbestos fibers, such as glass fibers, are impregnated with thermosetting resin such as phenolic resin, which is used as a binder for these fiber materials, during the production of friction materials. Due to the low retention capacity, manufacturing workability is reduced and it is difficult to obtain high-strength friction materials.Friction materials using the same inorganic fibers as fiber materials other than asbestos fibers have a coefficient of friction that varies depending on the temperature at which they are used. This is because there are many problems that need to be solved, such as a large difference and a decrease in the coefficient of friction at high temperatures. As a result of extensive research in order to solve these problems, the present inventors have found that in a composite yarn consisting of a core material and fibers intertwined with it, rayon fibers with a relatively high resin retention capacity are used as the core material and the fibers intertwined with the core material. By mixing it with the fibers to be intertwined and further twisting if necessary to form a string with a thickness of 50 to 30,000 tex, and impregnating it with a thermosetting resin, it is easy to manufacture and machine. We discovered that an extremely high-quality friction material with high strength and little change in the coefficient of friction due to temperature changes can be obtained.
The present invention has been accomplished. That is, in the present invention, a core material made of a plurality of rayon threads or a rayon thread and a metal wire is intertwined with mixed fibers made of rayon fibers and at least one selected from glass fibers and carbon fibers. Twist this further to make a thickness of 50
The object of the present invention is to provide a string-like body for a friction material, characterized in that it is constructed in the form of a string of ~30,000 tex and is impregnated with a thermosetting resin. As the core material of the string-like body of the present invention, a single rayon thread or a combination of a plurality of rayon threads and metal wires is used. The shape of the rayon thread or metal wire that forms this core material is filament, thread,
It can be made of any material such as thin string or ribbon. These are integrated into a core material by twisting a plurality of them, wrapping one around the other, weaving, or gluing them together. This metal wire includes brass wire, copper wire, zinc wire,
Aluminum wire, iron wire, etc. can be mentioned, but among these metal wires, particularly desirable are brass wire, copper wire, and zinc wire, which are relatively flexible and have good workability in manufacturing bulky strings. . By introducing these metal wires into the string-like body, the burst strength of the string-like body can be improved, and in order to improve thermal conductivity, the heat generated when used as a friction material is absorbed by heat conduction. It has the effect of controlling and prolonging its service life. Next, a mixture of rayon fibers and glass fibers, rayon fibers and carbon fibers, or rayon fibers, glass fibers, and carbon fibers is used as the fiber mixture to be intertwined with the core material.
A particularly desirable fiber mixture is glass fiber, which has an appropriate coefficient of friction and has the effect of increasing mechanical strength.
20 to 90% by weight, 5 to 80% by weight of rayon fiber, which has the effect of improving resin impregnation, improving entangling workability, and maintaining a high coefficient of friction at high temperatures; Carbon fiber is added at a rate of 5% by weight or less, which has been finely adjusted and has the effect of improving thermal conductivity and preventing temperature rise during friction. By using the fiber mixture at this mixing ratio as the intertwined fibers, a bulky string-like body can be efficiently produced, and a particularly high-quality friction material can be obtained. Further, various cutting lengths of the respective fibers constituting the fiber mixture used as the entangled fibers can be used, but it is particularly desirable that the average cutting length be in the range of 1 to 200 mm. In order to entangle this fiber mixture with the core material, the fibers are opened into cotton-like lumps, formed into a thin sheet, cut into a long and thin tape, and entwined around the core material. Either wrap the fiber mixture around the core material and fix it by twisting as necessary, or spread the fiber mixture around the stretched core material, spray it with a glue such as polyvinyl alcohol to adhere it around the core material, and then twist it. to fix it. The bulky yarn thus obtained may be used as it is, or may be twisted into a plurality of yarns to obtain the required thickness. The composite of the core material and the fiber mixture must be formed into a string having a thickness of 50 to 30,000 tex. Text here means length
It is a unit of thickness expressed in grams per 1000m. If the thickness of this string-like body is thinner than 50 tex, the production time will be longer when manufacturing the friction material of the required size, which will worsen the manufacturing workability. , the impregnation time for thermosetting resins such as phenolic resins, urea resins, and melamine resins as binders becomes longer, which not only impairs manufacturing workability but also causes the fiber distribution state of the finished friction material to become coarse. Mechanical strength such as burst strength (number of revolutions at which breakage occurs, unit: rpm) decreases. Next, this string-like body is impregnated with a thermosetting resin such as a phenol resin, a urea resin, or a melamine resin, and then dried. As a result, the string-like body for friction material of the present invention is obtained. This string-like body contains various friction modifiers (polytetrafluoroethylene molybdenum disulfide, graphite, barite, cashew dust, rubber, cork, etc.) and various fillers (mica, etc.) to finely adjust the friction coefficient as desired. , vermiculite carbonate, chromium oxide, aluminum oxide, zirconium oxide, silicon oxide, diatomaceous earth, glass powder, iron oxide, etc.). By containing a filler or the like, a friction material of even higher quality can be obtained. When the string-like body of the present invention is used as a friction material, it can be used as it is, or it can be used in a structure in which a plurality of string-like bodies are further twisted together (see Fig. 5), or in a structure in which a plurality of string-like bodies are further twisted together. It can also be used in a structure in which it is wound around a metal wire (see FIGS. 6 and 7). Examples of methods for manufacturing friction materials such as clutch facings, brake linings, and disk pads using the string-like body for friction materials of the present invention include:
This is a so-called wet manufacturing method in which a thick-walled pipe is formed using the filament winding method, heated and cured, and then the cured pipe is cut into slices of a predetermined thickness to form the friction material. There are manufacturing methods such as a so-called dry manufacturing method in which the predried thermosetting resin-impregnated composite is preformed into a predetermined shape and then placed in a mold and heated and pressed to form a friction material. The friction material string-like body of the present invention can be easily manufactured as a friction material according to the above-described manufacturing method. Next, the present invention will be specifically explained using Examples and Comparative Examples. Embodiment FIGS. 1 to 7 are cross-sectional model views of the friction material string-like bodies of sample numbers 1 to 7 of this embodiment, respectively. FIG. 8 and FIG. 9 are model cross-sectional views of the friction material string-like bodies of sample numbers 1 and 2 of comparative examples, respectively. FIG. 10 is a perspective view of the string-like body shown in FIG. 1. (1) Composition and preparation method of string-like sample. (1) Example sample number 1 (Fig. 1) Three rayon cotton yarns 1 with a thickness of 15 tex
Mixed fibers 2 for interlacing, which are composed of 70% by weight of glass fibers having an average length of 50 mm and 30% by weight of rayon staples having an average length of 50 mm, were interlaced to have a thickness of 840 tex. (2) Example sample number 2 (Figure 2) Three rayon soft threads 1 with a thickness of 15 tex and one brass wire 3 with a thickness of 25 tex have an average length.
Mixed fibers 2 for interlacing, which are composed of 40% by weight of glass fibers of 50 mm and 60% by weight of rayon staples having an average length of 50 mm, are interlaced to have a thickness of 860 tex. (3) Example sample number 3 (Figure 3) Three rayon cotton yarns 1 with a thickness of 15 tex
60% by weight of glass fibers with an average length of 50mm and 3% by weight of carbon fibers with an average length of 50mm and an average length of
This is a bulky string with a thickness of 2540 tex, which is made by twisting and integrating three pieces of interlacing mixed fibers 2 consisting of 37% by weight of 25 mm rayon staples to a thickness of 840 tex. (4) Example sample number 4 (Figure 4) Three rayon cotton yarns 1 with a thickness of 15 tex
Mixed fibers 2 for interlacing consisting of 70% by weight of glass fibers with an average length of 50 mm and 30% by weight of rayon staples with an average length of 50 mm were interlaced to have a thickness of 840 tex.
It is a bulky string with a thickness of 2565 tex made by twisting and integrating a single brass wire 3 with a thickness of 25 tex. (5) Example sample number 5 (Figure 5) Three rayon threads 4 with a thickness of 15 tex and one copper wire 5 with a thickness of 25 tex have an average length of 50 mm.
Three strands of intertwined mixed fiber 2 consisting of 50% by weight of glass fiber, 2% by weight of carbon fiber with an average length of 50mm, and 48% by weight of rayon staple with an average length of 25mm are twisted together and integrated. It is a bulky string with a thickness of 2,600 tex. (6) Example sample number 6 (Figure 6) Six rayon staple yarns 1 with a thickness of 15 tex
and one brass wire 3 with a thickness of 25 tex, 70% by weight of glass fiber with an average length of 50 mm and an average length of 50 mm.
4 strings of 900 tex thick and 50 tex thick brass wire 3 intertwined with interlacing mixed fiber 2 consisting of 2% by weight of carbon fiber of mm and 28% of rayon staple of average length 25 mm Thickness 3800 made by twisting and integrating
It is a bulky string from Tekkusu. (7) Example sample number 7 (Figure 7) Three rayon cotton yarns 1 with a thickness of 15 tex
One brass wire 3 with a thickness of 50 tex and 80% by weight glass fiber with an average length of 50 mm and an average length of 25 mm.
Thickness 920 with interlaced mixed fiber 2 composed of 20% by weight of rayon staple.
Thickness made by bundling five cords made by wrapping three tex strings in the longitudinal direction of 50 tex thick brass wire 3 and combining them by burning them together.
It is a bulky string of 15,000 tex. (8) Comparative Example Sample No. 1 (Fig. 8) Asbestos/rayon staple mixed fiber 6 consisting of 15% by weight of rayon staples and 85% by weight of asbestos with an average length of 25 mm was twisted together to form a fiber with a thickness of 800 mm. It is also a bulky string made of asbestos with a thickness of 2,500 tex, which is made by twisting together three tex strings and one brass wire 3 with a thickness of 25 tex. (9) Comparative Example Sample No. 2 (Figure 9) Asbestos/rayon staple made of 15% by weight of rayon staple with an average length of 25mm and 85% by weight of asbestos on one brass wire 3 with a thickness of 25 tex. This is a bulky string made of asbestos with a thickness of 2800 tex, which is made by bundling three 900 tex strings intertwined with mixed fibers 6 and integrating them by twisting them together. (2) Molding method and characteristics of clutch facing Each of the above string-like samples was impregnated with melamine resin, pre-dried, and the pre-dried melamine resin-impregnated bulky string was wound into a spiral shape to form a donut. This preform is preformed into
Place it in a press mold at 250℃ and press mold it.
A clutch facing sample was prepared. For each clutch facing sample with different bulky strings made using this method,
The friction coefficient and wear rate at 100°C, 150°C and 200°C were measured according to JIS D4411-1971 (automobile clutch facings) and the results are shown in Table 1. Furthermore, burst strength (= rotational breaking strength)
were measured and the results are also shown in Table 1.

【table】

[Table] From Table 1, the clutch facings of sample codes I to I using the string-like bodies of the present invention (sample numbers 1 to 7) are the same as those of sample codes C and I of comparative examples using asbestos. It can be seen that the friction coefficient, wear rate, and burst strength of this material are equivalent to or better than those of clutch facings, indicating that it has extremely excellent properties as a friction material.

[Brief explanation of the drawing]

1 to 7 are cross-sectional views of models showing examples of the string-like body for friction materials of the present invention, and FIGS. 8 and 9
The figure is a sectional view of a model showing an example of a conventional string-like body for friction material using asbestos, and FIG. 10 is a perspective view of the example of FIG. 1. In the figure, numerals 1, 3, 4, and 5 are core materials, and 2 and 6 are intertwined fiber mixtures.

Claims (1)

[Scope of Claims] 1 A core material made of a plurality of rayon threads or a rayon thread and a metal wire is intertwined with mixed fibers made of rayon fibers and at least one selected from glass fibers and carbon fibers, A string-like body for a friction material, characterized in that the string-like body is further burned together as the case may be, formed into a string-like body having a thickness of 50 to 30,000 tex, and impregnated with a thermosetting resin. 2. The string-like body for a friction material according to claim 1, wherein the mixed fibers consist of 20 to 90% by weight of glass fibers, 5 to 80% by weight of rayon fibers, and 0 to 5% by weight of carbon fibers.