JPS62227709A - Method of vulcanizing piezo rubber sheet equipped with electrode - Google Patents

Abstract

PURPOSE:To prevent the electric wave receiving sensitivity characteristics from deteriorating and the early stage deterioration due to overcure from occurring by a method wherein the surfaces of a semi-cured rubber sheet is covered with electrodes consisting of unvulcanized electrically-conductive rubber and then vulcanized so as to be made into an integral body. CONSTITUTION:Unvulcanized electrically-conductive rubber electrode sheets 2 and 2 are stuck to both surfaces of a semi-vulcanized piezo rubber sheet 1 so as to be fully vulcanized into a product. The product is excellent in electric wave receiving sensitivity which is the requisite for electric wave receiving element. This is because the fact that the air contained in the piezo rubber sheet 1 escapes from the surface of the rubber by expanding its volume due to the heat of semi-vulcanization performed on the rubber sheet 1 before the electrically- conductive rubber electrode sheets 2 are stuck to the rubber sheet 1 and dissipates to the atmosphere before the unvulcanized electrically-conductive rubber electrode sheets 2 and 2 are stuck to the surface of the rubber sheet 1 and that the strain and unevenness of the rubber sheet even existing before semi-vulcanization are eliminated by semi-vulcanization so as to smooth its surface and further that no drooping at the periphery of the sheet develops when the electrically-conductive rubber electrode sheets are stuck in the unvulcanized state and furthermore that neither thicker portion nor thinner portion develops in the electrode sheet and consequently the thickness of the electrode sheet is nearly uniform.

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a method of vulcanizing a piezo rubber sheet with electrodes,
The piezo rubber sheet with electrodes has a field of application that can improve the yield of high-quality products that can be vulcanized.

(Prior art) Conventionally, a sheet of unvulcanized conductive rubber was placed on the surface of an unvulcanized piezo rubber sheet. The Fi electrode or base electrode is coated and simultaneously vulcanized to form an integrated product.

(Problems to be Solved by the Invention) Conventional piezo rubber sheets with electrodes, as described in the previous section, require the unvulcanized piezo rubber sheet and the unvulcanized electrodes to be vulcanized once. However, according to this conventional method, ■Pumping during vulcanization causes
The air contained within the piezo rubber sheet expands and floats bubbles on the surface, but the coating of the conductive rubber electrode makes it difficult for the bubbles to escape to the outside, and the pressure of the bubbles causes the conductive rubber electrode to float, so it is partially Poor adhesion; in many cases, the transfer sensitivity characteristics deteriorate even if integral molding is performed due to curling and appearance. ■If a non-metallic conductive material such as carbon is used for the conductive rubber electrode, the thermal conductivity will be poor and the piezo rubber sheet will be insufficiently vulcanized. Furthermore, if the vulcanization time is increased in order to avoid insufficient vulcanization, the conductive rubber electrode on the surface becomes over-vulcanized, resulting in the production of piezo rubber sheets with electrodes that age quickly. ■Before vulcanization, the piezo rubber sheet has undulations and unevenness, so if it is vulcanized together with the conductive rubber electrode, the undulations and unevenness will easily appear on the product surface. In addition, the peripheral part of the piezo rubber sheet sag during vulcanization.
The thickness of the electrode became extremely thin in some partsl) )'7
This is one of the causes of poor transfer sensitivity characteristics. There are drawbacks such as.

The problem of the method of the present invention is to develop a vulcanization method that eliminates these drawbacks.

(Means for Solving the Problems) The present invention aims to solve the problems stated in Section 111, and includes vulcanizing a piezo rubber sheet to a semi-vulcanized state, and The VT feature is formed by coating the surface of a rubber sheet with an electrode made of unvulcanized conductive rubber, and vulcanizing the semi-vulcanized piezo rubber sheet and the electrode described in ii+i to form an integrated product.

A preferred embodiment of the invention is explained to a dog.

(Example) The composition and molding thickness of the piezo rubber sheet 1 and the conductive rubber electrode 2 are the same as before, and the piezo rubber sheet 1 has a volume ratio of lead titanate and chloroprene rubber of 60:40.
Then, apply an appropriate amount of vulcanizing agent to the outside, and cross-wire and roll to a thickness of 3 mm. *The conductive rubber electrode 2 is made by cross-rolling 100 parts of chloroprene rubber, adding 25 parts of Ketchen Double Black EC, which is a carbon-based conductive agent, and 10.5 parts of a vulcanizing agent made of a blend, and then cross-rolling the mixture. Shape into a sheet with a diameter of 0.51.

Conventionally, as mentioned above, unvulcanized conductive rubber electrode sheets were pasted on both sides of an unvulcanized piezo rubber sheet and heated at 170°C.
Previously, simultaneous vulcanization was performed under the conditions of 25 + ain, but in the present invention, the piezo rubber sheet 1 shown in FIG.
Semi-vulcanization was performed under the conditions of 70° C. and 15 ml, and unvulcanized conductive rubber electrode sheets 2.2 were pasted on both sides of the semi-vulcanized piezo rubber sheet 1 as shown in FIG. As shown, press vulcanizer 11. 170℃ 1
5 + ain.

Main vulcanization was performed under the following conditions to obtain the product shown in Figure 4.

(Functions and Effects) As a control product, a piezo rubber sheet with electrodes was manufactured using the conventional manufacturing method, and polarized under the same polarization conditions as the product shown in Figure 4 manufactured using the method of the present invention, and the results of each were compared.
The results shown in the following table were obtained.

As is clear from the above, all products manufactured by the method of the present invention have excellent results, and in particular, the receiving sensitivity, which is a requirement for a delivery element, is excellent by about 1.4 dB.

This result shows that when using the method of the present invention, (1) the air contained in the piezo rubber 1 expands in volume due to the heat of semi-vulcanization before pasting the conductive rubber electrode sheet 2 and escapes to the surface; Even if the conductive rubber electrode sheet 2.2 is emitted into the air before it is applied to the surface, and even if there are distortions or irregularities immediately after semi-vulcanization, the surface will be smoothed by the pressure during semi-vulcanization, and the conductive rubber electrode This is thought to be due to the fact that when the sheet is pasted and unvulcanized, the peripheral edge does not sag, the electrode sheet does not have thick or thin parts, and the thickness is made almost uniform. In addition, piezo rubber sheet 1 and conductive rubber electrode sheet 2
Since both methods do not result in over- or under-vulcanization, the lead wires can be easily hung on the electrodes, and the production of defective products due to cracks is suppressed, and the tensile strength is improved compared to the conventional vulcanization method. Because it can be made better than the products made by rubber, we can expect an expansion of applications that utilize the flexibility of rubber.

In addition to the conductive rubber sheet described above, the electrode 2.2 may be formed by applying a conductive rubber paste made by dissolving a mixture of raw rubber, metal powder, and vulcanizing agent in a solvent such as toluene to form a liquid.

[Brief explanation of drawings]

The attached drawings are for explaining the method of the present invention, and Fig. M1 is a perspective view of a semi-vulcanized piezo rubber sheet 1, and Fig. 2 shows a rubber electrode 2.2 provided on both surfaces of the piezo rubber sheet 1 shown in Fig. 1. A perspective view of the condition, Figure 3 is a side view showing press vulcanization, and Figure 4 is a side view showing press vulcanization.
The figure is a perspective view of a piezo rubber sheet with electrodes according to the method of the present invention 61 → piezo rubber sheet 2 → conductive rubber electrode

Claims (1)

[Claims] A piezo rubber sheet is vulcanized to a semi-vulcanized state, an electrode made of unvulcanized conductive rubber is coated on the surface of the semi-vulcanized rubber sheet, and the semi-vulcanized piezo rubber sheet and the unvulcanized A method for vulcanizing a piezo rubber sheet with electrodes, which is characterized by vulcanizing the electrodes to form an integrated object.