JPS6032649B2 - Manufacturing method for elastic molded products - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an elastic molded product in which a fibrous substance is mixed into an elastic base, especially one having a velvety surface, which is used for diaphragm edges for speakers, turntables for record players, etc. The present invention relates to a method of manufacturing a suitable elastic molded article.

Recently, materials in which fibrous substances are mixed into an elastic substrate have come to be used as backing materials, such as edges of diaphragms for speaker power, in order to obtain high rigidity.

However, the appearance of a rubber-like elastic member used, for example, in the edge of a speaker diaphragm is not very good. Therefore, the only way to improve the appearance of such rubber-like elastic members is to paint them, but painting does not only fail to provide a surface with an excellent appearance;
This is not a preferable method since it may impair the elasticity of the rubber. The present invention was invented in view of the above-mentioned circumstances, and includes a step of mixing 3 to 2 parts by weight of a fibrous substance having chemical resistance into an elastic substrate having a cloud cover of 10 parts, and and exposing the fibrous material by etching away the surface area of the elastic substrate to a depth of 5 to 20 mm using a chemical that can corrode the fibrous material and leave the fibrous material. This relates to the manufacturing method of the product.

With this configuration, it is possible to obtain an elastic molded article having a velvety surface with excellent appearance without impairing the properties of the elastic substrate. The present invention uses an etching process to corrode and remove only the elastic substrate near the surface of the elastic molded product, thereby exposing a part of the fibrous substance mixed in the elastic substrate, and leaving the other parts inside the elastic substrate. It remains embedded in the
The amount of fibrous material exposed to the surface by removing the surface area of the elastic substrate is 5 to 1000 fibrous substances/fibers/fibers when viewed from the surface.
It is desirable that the length be about 2 ribs. In other words, it is desirable to mix 3 to 2 parts by weight of the fibrous material with respect to 3 parts by weight of the elastic substrate 10. That is, the fibrous material has 5
If the amount is less than 2 parts by weight (or 3 parts by weight based on 10 parts by weight of the elastic substrate), there will be little change in appearance, a sufficient velvety appearance will not be obtained, and the fibrous material will become more than 1000 strands on the surface. This is because if the amount of the fibrous material exceeds 2 parts per willow (or 2 parts by weight of the fibrous material relative to the parts by weight of the elastic substrate 10), the elasticity of the elastic substrate will be inhibited. Further, the amount (or depth) of the surface area of the elastic substrate to be removed is preferably about 5 to 20 mm.

The reason for this is that if the removal depth is less than 5 mm, the amount of fibrous material present in the surface area of the elastic molded product will be exposed to the surface too little, and a sufficient velvety surface will not be obtained. If it exceeds 20 degrees, some of the fibrous material may fall off from the elastic substrate, which is not preferable. In the present invention, the elastic substrate is NR [isoprene rubber (
natural rubber)], SBR (styrene, butadiene rubber),
BR (butadiene rubber), NBR [nitrile/butadiene rubber (nitrile rubber)], CR (k.

(roprene rubber), IR [isoprene rubber (synthetic natural rubber)], 11R [isobutylene/isoprene rubber (butyl rubber)], EPR (ethylene/propylene rubber), EP
T (ethylene propylene turborimer), EPDM
Rubber-like elastic bodies such as (ethylene propylene gen turborimer), unvulcanized polyurethane resins such as paraprene (trade name: manufactured by Hodogaya Chemical Industry Co., Ltd.), thermoplastic elastic bodies such as RB (trade name) etc. are available. Among these, especially natural rubber, BR, SBR, IR
It is preferable to use these materials because they are easy to perform etching treatment and easy to handle. In particular, it is most preferable to use SBR containing 50 to 8% by weight of butadiene from the viewpoint of physical properties such as high etching rate. Next, the fibrous material to be infiltrated into the elastic substrate containing the above-mentioned rubber and thermoplastic elastomer will be described. As the fibrous material usable in the present invention, it is desirable that the material satisfies the following conditions.

{a- Elastic modulus is lk9/side 2 or more, especially 4~
A value of about 55 n/skin 2 is preferable. 'b} Diameter is 1 to 1
Approximately 00 Buddha.

'c' length is 0.1 to 10 after mixing (kneading)
It should be about the size of a rib. {d' Must have acid resistance (chemical resistance).

Specifically, carbon fibers (including carbon fibers and graphite whiskers, etc.), glass woven fibers, kaolin fibers, polycrystalline fibers such as alumina, zirconia, and tylated boron, monocrystalline potassium titanate fibers, and silicon carbide. Composite fibers such as boron/tungsten/boron/fused silica, boron carbide/boron/tungsten, silicon carbide/tungsten, alumina whiskers, silicon carbide whiskers, polyfluoroethylene resins (e.g. Teflon fibers), silicone resin fibers etc. can be used as the fibrous material.

Natural fibers and synthetic fibers that have acid resistance can also be used, or even organic fibers can be used under the conditions a'~
{It can be used if it satisfies the d' term and particularly has acid resistance. Furthermore, as the etching solution used to expose such fibrous substances on the surface of the elastic substrate through chemical treatment, any etching solution that can corrode only the above-mentioned elastic substrate and leave the fibrous substances remaining can be used. For example, a mixture of chromic anhydride and sulfuric acid,
Examples include a mixed solution of hydrogen peroxide and sulfuric acid, a mixed solution of potassium bromate, phosphoric acid, and permanganate, and the like.

Further, carbon particles may be added to the elastic molded article manufactured according to the present invention for reinforcement.

It is practical for this carbon particle to have an average particle size of about 10 to 100 mm, specifically channel black (particle size: 10 to 30 mm), acetylene black (
Grain flea: 42 skins), HAF (Grain flea: 26-28 Buddhas),
FEF (particle size: 40-50 grain size), SRF (grain size: 60 grain size)
~80 m) etc. are mentioned as an example. Note that the content of carbon particles is preferably 0 to 6% by weight. The reason for this is that it is difficult to mix carbon particles into an elastic substrate in an amount exceeding 6% by weight, and furthermore, if the amount exceeds 6% by weight, the mixture loses its elasticity. Next, an embodiment of an elastic molded article manufactured according to the present invention and its manufacturing method will be described.

The elastic molded article produced in this example had the following composition.

JSR1507 (Product name: Manufactured by Japan Synthetic Rubber Co., Ltd.) 10 parts by weight HAF
(High Ablation Furnace) (Product name: Manufactured by Asahi Carbon Co., Ltd.) 1. Weight part training force T200 (Product name:
(manufactured by Toray Industries) 1 weight part ANTAGE 30 (
Product name: Kawaguchi Chemical Industry Co., Ltd.) 1 part by weight Antige R
D (product name: manufactured by Kawaguchi Chemical Industries, Ltd.) 1 part by weight Accel NS (product name: manufactured by Kawaguchi Chemical Industries, Ltd.) 1 part by weight Accel TET (product name: manufactured by Kawaguchi Chemical Industries, Ltd.) 0.
5 parts by weight Actor R (product name: manufactured by Kawaguchi Chemical Industry Co., Ltd.)
0.75 parts by weight In this example, S was used as the elastic base.
JSR1, a type of BR (styrene ptadiene rubber)
507 (butadiene content: 76.5% by weight),
Moreover, Trading Card T200, which is a type of carbon fiber, was used as the fibrous material.

That is, 100 parts by weight of liquid JSR1507 is mixed with 10 parts by weight of HAF as a reinforcing material, and further, Young's modulus is 2 on/side 2 or more, tensile strength is 200k9/rib2 or more,
Diameter 3.5 Buddha, length approximately 6. Add 1 part by weight of Trading Card T200 and then mix with a roller. By this mixing, the carbon fibers are cut to an average length of about 1.0 mm. Furthermore, 1 part by weight of ANTAGE 30 and 1 part by weight of ANTAGE RD are added to this liquid mixture as an anti-aging agent, and 1 part by weight of ACCEL NS as a vulcanization accelerator.
, 0.5 parts by weight of Accel TET and 0.75 parts by weight of Acta-R are added thereto, and then this liquid mixture is injected into a mold heated to a predetermined temperature and molded. In this case, the carbon fibers may be mixed irregularly (orientated or not) within the elastic substrate. FIG. 1 is a microscopic photograph (magnification: 8.3 degrees) of the surface of an elastic molded product before etching treatment (the scale shown at the top is 1 scale on the 1 side),
As is clear from this photograph, almost no carbon fibers are found on the surface of the elastic molded product. Therefore, as shown in an exaggerated manner in FIG. 2, it can be seen that the carbon fibers 1 are completely embedded within the elastic base 2. Therefore, the surface of the above-mentioned elastic molded product exhibits the same appearance as the elastic substrate and does not have a velvety appearance. Next, the obtained elastic molded article is etched for about 2 hours with a mixed solution of 500 m/s of chromic anhydride and 200 m/s of sulfuric acid.

By this etching process, only the elastic substrate near the surface of the elastic molded article is corroded and removed, while the carbon fibers present near the surface are not corroded and remain as they are and exposed on the surface. In other words, the exposed carbon fibers are held partially embedded within the elastic base. This gives the surface of the elastic molded article a black velvety appearance. Figure 3 is a micrograph (magnification: 8.9) of the surface of an elastic molded product with a velvety surface manufactured as described above (the scale shown at the top is 1 scale = 1 skin). ), and is made of carbon fiber with exposed shiny parts. FIG. 4 shows this state in an exaggerated manner. 1st
As is clear from comparison with the figure and FIG. 2, carbon fibers that were not seen on the surface of the elastic molded article before the etching treatment became visible after the etching treatment. In this example, since the carbon fibers are mixed irregularly, it is difficult to make a general statement, but on average about 20 carbon fibers are mixed per side 2.
The carbon fiber of the book was exposed. The elastic molded product obtained as described above has a velvety surface and has a realistic appearance, so it is suitable for use, for example, as a diaphragm edge for a speaker, a turntable for a record player, etc. .

Also, the carbon fibers exposed on the surface are relatively flexible, so
As shown in FIG. 4, it is easy to lie on the surface, so the surface friction coefficient is small and the feel is good. Furthermore, the exposed carbon fibers provide strong adhesive strength when an adhesive or the like is applied, which is convenient when adhering a molded product coated with this adhesive to a predetermined location. Although the present invention has been described above based on one embodiment, this embodiment can be further modified based on the technical idea of the present invention.

For example, in this embodiment, carbon fibers are randomly mixed into the elastic substrate, but the carbon fibers may be oriented in a predetermined direction. In this case, as shown in FIG. 5, the above-mentioned liquid mixture 12 mixed with the fibrous material is poured into approximately the center of the mold 3 which is heated to a predetermined temperature. The mold 5 heated to a predetermined temperature is placed above the mold 3 described above, and the liquid mixture 12 is sandwiched between the molds 3 and 5 as shown in FIG. do. Next, when the mold 5 is gradually lowered toward the mold 3, the liquid mixture 12 is pushed into the mold 3 by the pressure of the molds 3 and 5.
The fibrous material flows in the direction of arrow A from the center, that is, radially from this center, and as a result, the fibrous material also maintains this directionality and is finally oriented radially as shown in FIG. In this way, an elastic molded product in which the fibrous material 1 is oriented in the radial direction, for example a speaker diaphragm edge 10 as shown in FIG. 7, is obtained.

By etching the surface of the diaphragm edge 10 as described above, it can be made into a velvet-like surface. In such a speaker diaphragm edge, the fibrous material is oriented in the ridge direction, so the edge can expand and contract extremely well in the circumferential direction, preventing the edge from wrinkling when the diaphragm vibrates. Something happens. In addition, it is possible to prevent the generation of Korean sound at the edge portion, and it is possible to make the frequency characteristics very good. Also, during the etching process, the etching depth should be set to 5~2 as described above.
By adjusting within the range of 0, various velvety appearances can be obtained. Since the present invention has the above-described configuration, a sufficient velvety surface can be obtained without impairing the elasticity of the substrate. . Therefore, it is possible to effectively improve the appearance of elastic molded products, which has been difficult with conventional techniques.

[Brief explanation of drawings]

1 to 7 are for explaining the present invention, and FIG. 1 is a micrograph of the surface area of an elastic molded product containing a fibrous material before etching treatment (magnification: 8. sound)
, Fig. 2 is a partially enlarged vertical cross-sectional view of the elastic molded product shown in Fig. 1, Fig. 3 is a micrograph of the surface area of the above-mentioned elastic molded product after etching treatment, and Fig. 4 is the elastic molded product shown in Fig. 3. FIG. 5 is a vertical cross-sectional view of the mold used to form the frequency edge, FIG. 6 is a partially enlarged plan view of the diaphragm edge, and FIG. 7 is the W- It is a longitudinal cross-sectional view along skin lines. In addition, in the symbols used in the drawings, 1... fibrous material, 2... elastic base. Figure 1 Figure 3 Figure 2 Figure 4 Figure 5 Figure 6 Figure 7

Claims (1)

[Claims] 1. Mixing 3 to 20 parts by weight of a chemical-resistant fibrous substance into 100 parts by weight of the elastic substrate, and a chemical that can corrode only the elastic substrate and leave the fibrous substance, thereby improving the elasticity. A method for producing an elastic molded article, comprising the steps of: etching away the surface region of the base to a depth of 5 to 20 μm to expose the fibrous material.