JPS631342B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a molding material that is lightweight, has high rigidity, high elasticity, and high internal loss and is suitable for forming acoustic devices such as diaphragms, head shells, tone arms, and cantilevers. BACKGROUND OF THE INVENTION Materials for the vibration systems of audio equipment, such as diaphragms and cantilevers, are required to be lightweight, have high elasticity, high rigidity, and have high internal loss. This is because it is highly rigid and lightweight so that it can reproduce a wide range of sounds up to the high range without causing split vibration, and it also suppresses the sudden rise in sound pressure near the resonance frequency of the high range and has a large fall characteristic. This is because high internal loss is required. In addition, tone arm components such as head shells and tone arms are lightweight and highly rigid in order to have sufficient strength even if the wall thickness is thin to reduce the equivalent mass of the needle tip.
This is because it is required to have high elasticity and high internal loss in order to absorb split vibration.
However, metals such as aluminum, titanium, and beryllium have traditionally been used as highly elastic and lightweight materials.
CFRP and the like are used for diaphragms, head shells, etc., but these materials have a problem of low internal loss. On the other hand, paper, synthetic resin, composite materials of these materials, etc. are used for diaphragms as materials with high internal loss, but these materials have low elastic modulus and the ratio of elastic modulus E to density ρ (specific elastic modulus) ) There is also the problem of low E/ρ, and for a long time it has not been possible to obtain a material that has both the characteristics of being lightweight, high elasticity, and high internal loss.
Recently, the inventors of the present invention have proposed patent application No. 54-64949.
(Refer to Japanese Unexamined Patent Publication No. 55-157630), we proposed a molding material that is lightweight, highly elastic, and has high internal loss. This material is lightweight
It has excellent properties comparable to metal materials in terms of high elasticity and comparable to paper in terms of high internal loss. However, this material has problems in high temperature resistance, making it difficult to use as a molding material for car stereo equipment, which is required to withstand severe temperature conditions such as exposure to direct sunlight, especially in midsummer. The present invention has been made in view of such conventional problems, and it is an object of the present invention to provide a molding material for audio equipment that is lightweight, highly elastic, has excellent acoustic properties such as high internal loss, and is also excellent in high temperature resistance. This is the purpose. The present invention will be explained in detail below. The present invention is characterized by post-chlorinated vinyl chloride alone or a mixture of post-chlorinated vinyl chloride and polymethyl methacrylate, and if necessary, nitrile butadiene rubber (NBR), butyl rubber (IIR),
It is a molding material for audio equipment that is a mixture of a mixed material containing a rubber material such as styrene butadiene rubber (SBR) and flaky graphite powder. The present invention is also characterized by a molding material in which graphite powder is oriented in one direction among the above-mentioned molding materials. When discussing heat resistance at the temperature at which the elastic modulus is halved, post-chlorinated vinyl chloride has a heat resistance that is 10 to 20°C higher than that of vinyl chloride resin, and polymethyl methacrylate (PMMA) has a heat resistance that is 10°C higher than that of vinyl chloride resin. It's nearby and expensive. Therefore, these synthetic resins have better heat resistance than molding materials based on vinyl chloride resins. Rubber-based materials contribute to improving internal loss due to their softness. The flaky graphite powder contributes to an improvement in the elastic modulus that cannot be expected from a resin alone, and especially when its orientation is aligned in one direction, the elastic modulus is significantly improved. The flaky graphite powder preferably has an average particle size of about 20 μm or less, particularly 5 μm or less.
In addition, the blending ratio of graphite powder and resin is
If it is in the range of 10 to 90 wt% and 90 to 10 wt% of resin, graphite powder can be expected to improve the elastic modulus, and it will not impair the moldability of the molding material and will hardly cause embrittlement of the molded product. 50-75wt%,
When the resin content is 50 to 25 wt%, the properties are significantly improved. PMMA is widely used as a processing aid for post-chlorinated vinyl chloride, but the blending ratio of the two can be arbitrarily determined and can be changed depending on the shape and properties of the intended molded product. The rubber material is added as needed in the range of 2 to 50 wt% to the resin, and if it is added about 10 wt%, the elastic modulus E
decreases by about 20%, but the internal loss tanδ decreases by about 1.5 to 2.
You can see a two-fold improvement. The resin and graphite powder are kneaded while being heated using a kneader or rolls to a temperature at which the resin softens. Add plasticizers and stabilizers if necessary. In the case of kneading with rolls, the molding material is obtained as a rolled sheet material, the graphite powder is oriented parallel to the sheet surface, and the material itself has a high elastic modulus before molding. The molding material obtained above can be expected to significantly improve its elastic modulus by being molded so that the graphite powder is oriented along the surface of the molded product, so press molding or compression can be used to obtain the desired molded product. It is better to use a molding method. However, when the material itself is rolled into a sheet shape and graphite powder is oriented, vacuum forming or pressure forming may also be used. The present invention will now be explained based on examples. [Example 1] Post-chlorinated vinyl chloride 100 parts by weight Flake graphite powder 200 〃 Lead stearate (stabilizer) 5 〃 DOP (plasticizer) 10 〃 [Example 2] Post-chlorinated vinyl chloride 100 parts by weight Polymethyl Methacrylate 5 Scale graphite powder 150 Lead stearate 2 DOP 10 [Example 3] Post-chlorinated vinyl chloride 100 parts by weight IIR 10 Scale graphite powder 200 Lead stearate 5 DOP 10 [ Examples 4] Post-chlorinated vinyl chloride 100 parts by weight Polymethyl methacrylate 5 〃 IIR 10 〃 Scale-like graphite powder 150 〃 Lead stearate 2 〃 DOP 10 〃 [Comparative example] Vinyl chloride resin 100 parts by weight Scale-like graphite powder 200 〃 Stearic acid Lead 5 〃 DOP 10 〃 Each powder is heated in a kneader at 150 to 160℃ with the above blending ratio.
The mixture was kneaded under heating to obtain a kneaded product. In addition, in order to obtain orientation of graphite, the above-mentioned kneaded material was passed through rollers many times to obtain a sheet material. The physical properties of these materials are shown in the table below.

[Table] As is clear from the above, the molding material of the present invention can be made lightweight by molding using a forming method that orients graphite powder along the surface, or by using a material with graphite powder oriented in advance. It is possible to dredge metal materials such as aluminum with high elasticity and a ratio of elastic modulus to density of E/ρ, and to form molded products that have a high internal loss comparable to that of paper. The temperature characteristics are also improved by about 20 degrees Celsius compared to conventional graphite-containing resin materials, and the molded product does not deform even when heated to about 120 degrees Celsius. Therefore, it is suitable for use in forming acoustic devices such as diaphragms, headshells, tone arms, cantilevers, etc. that require light weight, high elasticity, and high internal loss. Due to its lightweight, high elasticity, and high internal loss characteristics, it can also be used to mold a wide range of audio equipment structures, such as speaker horns, speaker cabinets, acoustic lenses, equalizers, speaker frames, and turntable sheets. can. Furthermore, since it is resistant to high temperatures, it can be widely used for molding audio equipment, especially car stereos.

Claims (1)

[Scope of Claims] 1. A molding material for audio equipment whose main components are post-chlorinated vinyl chloride and flaky graphite powder. 2. A molding material for audio equipment, characterized in that the main components are post-chlorinated vinyl chloride and flaky graphite powder, and the flaky graphite powder is oriented in one direction. 3. A molding material for audio equipment whose main components are post-chlorinated vinyl chloride, polymethyl methacrylate, and flaky graphite powder. 4. A molding material for audio equipment, characterized in that the main components are post-chlorinated vinyl chloride, polymethyl methacrylate, and flaky graphite powder, and the flaky graphite powder is oriented in one direction. 5. A molding material for audio equipment whose main components are post-chlorinated vinyl chloride, flaky graphite powder, and a rubber material. 6. A molding material for audio equipment, which contains post-chlorinated vinyl chloride, flaky graphite powder, and a rubber-based material as main components, and is characterized in that the flaky graphite powder is oriented in one direction. 7. A molding material for audio equipment whose main components are post-chlorinated vinyl chloride, polymethyl methacrylate, flaky graphite powder, and a rubber material. 8. A molding material for audio equipment, the main components being post-chlorinated vinyl chloride, polymethyl methacrylate, flaky graphite powder, and a rubber-based material, and characterized in that the flaky graphite powder is oriented in one direction.