JPH0238956Y2 - - Google Patents

Description

[Detailed explanation of the idea]

(Industrial Application Field) The present invention relates to threads for friction materials, more specifically, threads constituting friction materials used for power transmission and control of automobiles such as clutch facings, brake linings, disc parts, etc. It is something. (Prior Art) Generally, as a material for friction materials such as the clutch facings, asbestos is used as the main raw material. However, in recent years, asbestos has been recognized to be carcinogenic, and this is becoming a social problem.
This could not be ignored in terms of the physical effects it would have on businesses that handle asbestos friction materials. Therefore, regulations on the handling of asbestos products in general, not just friction materials, are becoming extremely strict. Therefore, there has been a strong demand for the development of a substitute for asbestos as a material for friction materials. Therefore, an invention disclosed in Japanese Patent Publication No. 60-9526 is an invention made to meet such demands. That is, this invention involves mixing organic fibers with a non-asbestos base material such as inorganic fibers to form a sliver, then twisting the sliver, impregnating the sliver with a thermosetting resin, and then drying, shaping, and curing the sliver. This method was developed as a method for manufacturing friction materials. (Problems to be solved by the invention) (a) However, in the conventional technology as described above, the thread used for the friction material is a sliver made by blending organic fiber with inorganic fiber, and this is twisted into a sliver. Therefore, the yarn thus formed did not necessarily have high strength, especially tensile strength. In other words, inorganic fibers such as glass fibers and carbon fibers and organic fibers generally have a difference in elongation, so when they are mixed in advance to form a yarn, when the yarn is pulled, both Inadvertent separation or breakage of the fibers was apt to occur, and the tensile strength of the yarn was inevitably reduced. (b) Additionally, since organic fibers are generally carbonized by heating, their strength after heating is inevitably weakened. Due to the decrease in strength due to carbonization of organic fibers, separation between fibers tends to occur in the inorganic fibers themselves, and the strength of the entire yarn also decreases accordingly. As a result, when a friction material composed of the above-mentioned threads generates heat due to rotation, etc., a problem arises in that mechanical strength such as rotational breaking strength of the friction material itself decreases as the strength of the threads decreases. Ta. (c) Furthermore, when a friction material is formed from a yarn made of a blend of inorganic fibers and organic fibers as described above, the degree of dispersion of both of the above-mentioned fibers on the surface of the formed friction material increases. The friction material has a fine surface, so the surface of the friction material is homogeneous. However, in general, in order for friction materials to have wear resistance even after long-term use, the surface of the friction material must be appropriately peeled off and a new surface formed as the material is used. If the surface of the friction material is formed homogeneously due to the fine dispersion as described above, moderate peeling as described above will not occur, and the wear resistance will gradually deteriorate as it is used. There was a problem that it could be removed. (d) From the standpoint of strength and abrasion resistance, it is conceivable to form threads for friction materials only from inorganic fibers alone, but in reality it is impossible to form threads from only inorganic fibers. I couldn't do it. In other words, the yarn for friction materials as mentioned above has
Appropriate porosity is required, but such porosity is generally formed by carbonization of organic fibers.
The weft yarn had to contain organic fibers. Furthermore, from a manufacturing standpoint, it has been difficult to form threads for friction materials only from inorganic fibers. The present invention was developed as an improvement to threads for friction materials in order to solve these problems.
The purpose is to increase the tensile strength compared to conventional yarns and to also guarantee functions such as wear resistance of the friction material manufactured from the yarn. (Means for solving the problems) The present invention was made to solve the above problems in order to achieve the above purpose, and the means to solve the problems is to It is constructed by twisting the formed single yarn and the single yarn formed from a sliver of organic fiber. (Function) In other words, since inorganic fibers and organic fibers are formed separately into single yarns and each single yarn is twisted, even if there is a difference in elongation between inorganic fibers and organic fibers, each Since the single yarn is composed of fibers, there is less possibility that both fibers will be accidentally separated or cut even when the yarn is pulled, and the tensile strength of the yarn is improved. Moreover, since the inorganic fibers and the organic fibers are formed separately as single yarns, even if the yarns are heated and the organic fibers are carbonized, there is no fear that the inorganic fibers themselves will separate. Even when heated, the strength of the yarn does not decrease as much as conventional yarn. In addition, when a friction material is formed from such threads, each single thread consisting of both inorganic and organic fibers appears as one unit on the surface of the friction material. The degree of dispersion of the fibers in the friction material becomes a suitable roughness, and a new surface is formed depending on the frequency of use of the friction material, so that appropriate peeling occurs on that surface. (Example) Hereinafter, an example of the present invention will be described with reference to the drawings. FIG. 1 shows an example of yarn for friction materials such as clutch facings of automobiles. This clutch facing yarn 1 is made of chopped glass fiber strands and carbon fiber fiber chains. Two single yarns 3 formed from a sliver 2 obtained by blending a sliver 2 with a staple fiber and a staple fiber of a para-based wholly aromatic polyamide fiber (for example, Kevlar [registered trademark] of Dupont Co., Ltd. in the United States). 1 formed from sliver 4 obtained by blending cotton
It is constructed by twisting a single thread 5 and a single copper wire 6 with a wire diameter of about 0.15 mm. The composition of yarn 1 is as follows. Glass fiber 60 (weight%) Fully aromatic polyamide fiber 7 (weight%) Soft cotton 20 (weight%) Carbon fiber 3 (weight%) Cashew 10 (weight%) Copper wire 0.15 (wire diameter) And such a configuration The yarn 1 for friction material is made up of a sliver 2 made of a blend of two types of inorganic fibers and a sliver 4 made of a blend of two types of organic fibers, each of which forms single yarns 3 and 5 separately. However, since it is made by twisting both the single yarns 3 and 5 and the copper wire 6, compared to the conventional yarn made of a blend of both inorganic and organic fibers,
There is less possibility that the two fibers will be accidentally separated or cut, and the tensile strength of the yarn will be improved accordingly. Moreover, since the inorganic fibers and the organic fibers are each formed as a single yarn, even if the organic fibers are carbonized by heating, there is no risk of separation between the inorganic fibers, and the strength after heating is lower than that of the conventional fibers. It does not decrease as much as the yarn of . Furthermore, since it is constructed by twisting both the single yarns 3 and 5 and the copper wire 6, there is no possibility of unintended unraveling. In addition, when tests were conducted regarding the tensile load of the above embodiment and the conventional example, the results shown in the following Table 1 (the above embodiment) and the following Table 2 (conventional example) were obtained. The test method is asbestos thread (Japanese Industrial Standard: JIS
According to the test method of R3450-1979). The units of numerical values in the following table are kg, and the heating time was 30 minutes. In addition, in the following table, tensile strength is the value obtained by dividing the tensile load by the length of the thread. Furthermore, conventional yarn tests (Table 2 below) were conducted with the composition of the yarn, the weight percent of the fibers constituting the yarn, and the wire diameter of the metal wire all kept the same. As is clear from the following table, there is a remarkable difference in the tensile load of the yarn between the above example and the conventional example, and this difference was observed even after heating to 250℃, 300℃, etc. In the conventional example, the decrease in tensile load after heating was remarkable.

【table】

[Table] To explain an example of the method for manufacturing the yarn of the friction material mentioned above, first, a chopped strand of glass fiber is opened with an opener, and then a chopped strand of carbon fiber is opened. The fibers 7 in the blended state are passed through the opener again to form a so-called blended state, and the fibers 7 in the blended state are passed through a take-in 8, a transroller 9, and a cylinder 1 as shown in Fig. 5.
0. A sliver 2 as shown in FIG. 2 is formed through the dower 11, and a single yarn 3 as shown in the figure is formed from the sliver 2 through a thread. Next, the staple fibers of the para-based wholly aromatic polyamide fibers are unraveled, and staple fibers are mixed with the fibers to form a so-called mixed cotton state, and the fibers in the mixed state are formed into a sliver 4 as shown in Figure 3. The single yarn 5 as shown in the figure is formed by passing through the yarn. After that, two single yarns 3 formed of the blended fibers of glass fiber and carbon fiber, and one single yarn 5 formed of the blended fibers of para-based wholly aromatic polyamide fiber and cotton cotton. and 1 as above
By twisting real copper wires 6 as shown in FIG. 4, the thread 1 as described above is manufactured. In the case of forming the single yarn 3 made of glass fibers and carbon fibers, in the apparatus shown in FIG.
The speed of each roller is set so that the surface speed difference between each roller (speed difference at the contact point of the roller) between the cylinder 10 and the dower 11 is within 1 m/sec. The mixed cotton inorganic fiber sliver 2 formed through this process is of very high quality. Further, a pollan roller 12 for removing the waste of the blended cotton fiber remaining on the circumferential surface of the cylinder 10, which is hooked on a claw body (not shown) formed on the circumferential surface of the cylinder 10, is attached to the fifth roller. In the device shown in the figure, the cylinder 10 is provided not only on the upper side but also on the lower side, so even after the mixed cotton fibers are sent from the cylinder 10 to the dower 11, fiber waste remains on the circumferential surface of the cylinder 10. Without a problem,
Therefore, this is the sliver 2 of the above-mentioned mixed cotton inorganic fiber.
can be made of even higher quality. Therefore, since the blended inorganic fibers are of such high quality, there is no need to mix inorganic fibers with organic fibers in advance as in the past, and the sliver 2 and single yarn 3 can be formed only with inorganic fibers. I was able to do it. Next, to explain the case of manufacturing a clutch facing as an example of a friction material using the above-mentioned thread, first, the above-mentioned thread 1 is impregnated with a thermosetting resin, then formed into a desired shape and dried. By curing, the desired ring-shaped clutch facing 13 as shown in FIG. 6 is obtained. In this case, the clutch facing 13
As mentioned above, the thread 1 that constitutes the 1st part contains the copper wire 6, so this copper wire 6 causes a thermal diffusion phenomenon, and as a result, the impregnated resin melts and can be removed carelessly. There is nothing to be done. Then, on the surface of the clutch facing 13 formed in this way, each of the single yarns 3 and 5 of the above-mentioned inorganic and organic fibers appears as one unit, so the clutch facing 13
The degree of dispersion of the fibers on the surface of the clutch facing 13 has an appropriate roughness, and accordingly, appropriate peeling occurs on the surface so that a new surface is formed depending on the frequency of use of the clutch facing 13. Therefore, the wear resistance and other functions of the clutch facing 13 are not impaired even after long-term use. By the way, when the friction material (clutch facing) manufactured using the thread for friction material of this example was tested against a conventional material for burst strength, starting performance test, and friction property test, the following results were obtained. was gotten.

[Table] In other words, in the starting performance test and the friction property test, the friction material of this example and the conventional friction material were both good and no difference was observed, but as for the so-called burst strength, as mentioned above, A difference was observed, and it was confirmed that the friction material of this example had a stronger burst strength. In the above embodiment, the thread for the friction material is composed of chopped strands of glass fiber, fiber chops of carbon fiber, staple fibers of para-based wholly aromatic polyamide fiber, cotton wool, and copper wire. However, in addition to this, graphite, cashew dust, etc. may also be included. When graphite is mixed in, the coefficient of friction of the thread as a whole is lowered, which has the advantage of improving the wear resistance of the thread (friction material), and when cashew dust is mixed in,
This has the advantage that the friction coefficient of the thread itself and, by extension, the friction coefficient of the friction material are stabilized. Further, in this example, since the copper wire 6 was included in the thread 1, the above-mentioned preferable advantages were obtained; however,
It is not a condition that metal wires such as copper wires be included. still,
Types of metal wire include copper wire, brass, zinc,
It is also possible to use aluminum or the like. It is also possible to mix filaments of glass fibers into the organic fibers during the process from the sliver to the fiber. Furthermore, in this example, the chopped strands of glass fiber and the fiber chopped strands of carbon fiber are mixed together to form the single yarn 3 as a sliver, but it is not necessarily necessary to mix the two; Alternatively, the single yarn 3 may be formed by using only carbon fiber as a sliver. In short, it is sufficient that the single yarn 3 is formed of a sliver of inorganic fiber. Similarly, the material of the single yarn 5 of organic fiber is not limited to the blended fiber of aromatic polyamide fiber and cotton cotton as in the embodiment, and its type is not limited. In short, it is sufficient that the single yarn 5 is composed of the sliver 4 of organic fiber. As the aromatic polyamide fibers, in addition to the para-based fully aromatic polyamide fibers of the examples, meta-based fully aromatic polyamide fibers such as poly-m-phenylene isophthalimide may also be used.
Furthermore, such fully aromatic polyamide fibers (those with a structure in which amide bonds are directly connected to aromatic rings)
Other aromatic polyamide fibers may also be used. Further, in this embodiment, the yarn 1 is constructed by twisting two single yarns 3 and one single yarn 5, but the number of single yarns 3 and 5 is by no means limited to this. In short, inorganic fiber sliver 2 as above
It is sufficient that the yarn 1 is constructed by twisting a single yarn 3 formed from a sliver of organic fiber and a single yarn 5 formed from a sliver 4 of organic fiber. Incidentally, the yarn for the friction material of the present invention may be formed by twisting respective threads obtained from slivers of organic fibers and inorganic fibers. Further, the type of friction material is not limited to the clutch facing as in the embodiment, but may be, for example, a brake lining or disc part. (Effects of the invention) Since the invention has the above-mentioned features, it has achieved the following effects. (b) Instead of mixing inorganic fibers and organic fibers in advance as in the past, inorganic fiber slivers and organic fiber slivers are separately formed into single yarns, and both single yarns are twisted. The possibility of inadvertent separation or cutting of fibers due to the difference in elongation of both inorganic and organic fibers is significantly reduced compared to conventional methods, and the tensile strength of the yarn is therefore lower than that of conventional fibers. This has resulted in a remarkable effect of increasing the amount compared to . (b) Furthermore, since inorganic fibers and organic fibers are formed as a single yarn, even if the yarn is heated and the organic fibers in the yarn are carbonized, separation between the inorganic fibers themselves will occur as in the past. Therefore, there is an advantage that the strength of the yarn does not decrease as much as that of conventional yarns even when heated. As a result, even if the friction material made of such threads generates heat due to rotation or the like, the mechanical strength of the friction material does not decrease as in the conventional case. (c) Furthermore, on the surface of a friction material made of such threads, both the inorganic and organic fibers are not mixed together as one unit as in the past, but both fibers are mixed together. Because each single yarn formed by
The surface of the friction material has an appropriate roughness, so the surface of the friction material does not become a homogeneous surface like in the past, regardless of how it is used. This has the effect that appropriate peeling occurs and the wear resistance of the friction material is not impaired even after long-term use. (d) Furthermore, friction materials made of threads such as those mentioned above are resistant to centrifugal force compared to conventional friction materials made of blended cotton fiber threads, and are used in clutch facings, etc. This has the advantage that the so-called burst strength (rotational breaking strength) required for this product is better than that of conventional products.

[Brief explanation of the drawing]

FIG. 1 is a front view of a thread for a friction material as an example. FIG. 2 is a schematic explanatory diagram for explaining the process of forming a single yarn from a blended fiber of glass fiber and carbon fiber. FIG. 3 is a schematic explanatory diagram showing the process of forming a single yarn from a blended fiber of aromatic polyamide fiber and cotton cotton. FIG. 4 is a schematic explanatory diagram of the process of twisting single yarn. Fifth
The figure is a schematic explanatory diagram showing a process and apparatus for forming a sliver using the blended fibers of glass fiber and carbon fiber. FIG. 6 is a schematic front view of a clutch facing as an example of a friction material. 1... Thread, 2, 4... Sliver, 3, 5...
Single yarn.

Claims (1)

[Claims for Utility Model Registration] 1. A single yarn 3 formed by twisting at least an inorganic fiber sliver 2, and an organic fiber sliver 4.
A yarn for a friction material, characterized in that it is constituted by twisting a single yarn 5 formed by twisting. 2. The thread for a friction material according to claim 1, wherein the inorganic fiber is a blended fiber of glass fiber and carbon fiber. 3. The thread for a friction material according to claim 1, wherein the organic fiber is a blended fiber of aromatic polyamide fiber and cotton cotton.