JPH08285802A - Measuring method of progress state of cross-linking reaction of rubber by electrical characteristic value - Google Patents

Abstract

PURPOSE: To obtain a measuring method in which the cross-linking progress state of an uncross-linked rubber can be measured by a method wherein one pair of specific steels plates out of a plurality of internal steel plates which support uncross-linked laminated rubber are used as electrodes, a cycle voltage is applied and an electrical characteristic value is detected. CONSTITUTION: Sheetlike unvulcanized rubber and steel plates 14 to 18 are arranged alternately inside a mold 20 which has been preheated to the vulcanizing temperature of the rubbers, and an axial-direction load is applied to the sheetlike unvulcanized rubber and the steel plates 14 to 18 by an upper plate 41 and a push plate 43 by means of a press machine 50. The laminated rubber 13 which are arranged in the mold 20 raise their temperature with the passage of time so as to reach the vulcanizing temperature, of the rubber, which is the same temperature as the mold. Thereby, as the cross-linking reaction of the laminated rubbers 13 progresses, an electrical AC resistance value is raised once, it is then lowered, and it then displays a constant value. This indicates a point of time in which the time change rate of an AC resistance becomes nearly zero, and it is a point of time in which the cross- linking reaction of the laminated rubber 13 has been completed. Consequently, when a change in the time change rate of the electrical AC resistance is traced, the progress degree of the cross-linking reaction of the rubber can be observed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for measuring the progress state of rubber crosslinking reaction by detecting its electrical characteristic value.

[0002]

2. Description of the Related Art In the process of manufacturing uncrosslinked raw rubber into a practical rubber, heat is applied to the uncrosslinked rubber to cause a rapid crosslinking reaction between rubber molecules, which has sufficient elasticity. Change to practical rubber. In natural rubber and the like, since sulfur is used as an element that causes a crosslinking reaction, crosslinking is called “vulcanization”, but these are the same chemical reaction. Currently, the only clue for determining the progress of the crosslinking reaction is temperature and time. When observing the temperature, a temperature sensor is attached at an arbitrary position in the product, and the temperature inside the product is monitored based on the value obtained from the temperature sensor.

[0003]

By the way, when observing the temperature with the temperature sensor, the detected temperature naturally varies depending on the mounting position of the temperature sensor, and the shape of each product,
The state of temperature propagation inside also differs depending on the size. Therefore, reading the tendency of temperature propagation depending on the product shape and judging the progress state of the crosslinking reaction in the product from the applied temperature and time often depends on experience and intuition. Also,
In order to know whether the manufacturing conditions based on the combination of the applied temperature and time are truly appropriate conditions for the product, conduct a separate mechanical test, etc., and judge based on the results. There is no way. In this way, having to rely on experience and intuition in an important process in rubber manufacturing is a factor for increasing the variation in performance among individual products.

The present invention has been made in view of the above points, and an object thereof is an objective judgment material for the progress of a rubber crosslinking reaction which has heretofore been unknown objectively. The present invention provides a method for measuring the progress state of a rubber crosslinking reaction based on electrical characteristic values, which can provide an important judgment material in manufacturing control that suppresses the variation in performance among individual products. Especially.

[0005]

According to the present invention, the above object is achieved by a method of measuring the progress of the crosslinking reaction of an uncrosslinked rubber by detecting the electrical characteristic value of the rubber.

In the present invention, it is preferable to detect the impedance as the electric characteristic value. In this case, the steady value of the impedance, the time change rate reaching substantially zero, or both of them is detected to detect the uncrosslinked rubber. The completion of cross-linking may be measured. The uncrosslinked rubber as the object to be measured may be the rubber of the laminated rubber bearing, and in this example, any one of a pair of internal steel plates of the plurality of internal steel plates of the laminated rubber bearing is used as an electrode, and the electrical characteristic value of the rubber is It is preferable to apply a high frequency voltage to the pair of inner steel plates to detect the electrical characteristic value.

The present invention will be described in more detail below based on examples. The present invention is not limited to these examples.

[0008]

EXAMPLES The following examples show the case of measuring the electrical impedance at the time of manufacturing a laminated rubber bearing. As a measured object, the laminated rubber bearing 10 shown in FIG. 1 and a mold 20 for manufacturing the same were prepared. The rubber bearing 10 includes disc-shaped upper and lower connecting steel plates 11 and 12, and disc-shaped laminated rubber 13
And five disk-shaped internal steel plates 14, 15, 16, 17, and 18 embedded in the laminated rubber 13. Before heating, a sheet-shaped unvulcanized rubber was prepared, and the sheet-shaped unvulcanized rubber and the steel plates 14 to 18 were alternately stacked and arranged in the mold 20. The mold 20 includes an upper plate 41, a lower plate 42, and a push plate 43.
And 44, the intermediate ring 45, and the intermediate tubular body 21. One end of each of the lead wires 25, 26, 27, 28 and 29 is screwed to each of the inner steel plates 14 to 18 of the support 10,
The lead wires 25 to 29 were drawn out through the holes formed in the mold 20, and each of the internal steel plates 14 to 18 was used as an electrode. An AC voltage having a frequency of 100 kHz and a voltage of 1 V was applied between any two of the five electrodes, in this example, the inner steel plates 14 and 17, and the electrical impedance Z was measured during this period. The electrical characteristic measuring machine used for this measurement was a precision LCR meter (Yokogawa Hewlett Packard model 4286A) and a switch unit (Yokogawa Hewlett Packard model 3488).

For the measurement, first, a mold 20 preheated to the vulcanization temperature of the rubber is prepared, sheet-like unvulcanized rubber and steel plates 14 to 18 are alternately arranged in the mold 20, and the press machine is used. By 50, an axial load is applied to the sheet-shaped unvulcanized rubber and the steel plates 14 to 18 via the upper plate 41 and the push plate 43.

Initially, the laminated rubber 1 in a raw rubber state was placed in the mold 20 preheated to the vulcanization temperature of the rubber.
The temperature of No. 3 gradually increased with the elapse of time t, and was set to the vulcanization temperature of the rubber, which is the same temperature as that of the preheated mold 20 last. Accordingly, the electrical impedance Z is also shown in FIG.
It changed as shown in. Focusing on FIG. 2, the laminated rubber 1
It can be seen that the electrical impedance Z once increases and then decreases as the crosslinking reaction of 3 progresses. After decreasing to a certain value, the electric impedance Z began to show a substantially constant value Z1. Here, it was found that the time point t1 when the rate of change δZ / δt of the electrical impedance Z becomes substantially zero coincides with the time point when the crosslinking reaction of the laminated rubber 13 is completed. Therefore, it was found that the progress of the crosslinking reaction of the rubber can be observed by tracing the change in the rate of change δZ / δt of the electrical impedance Z with time.

In the above, the time t1 when the rate of change δZ / δt of the electrical impedance Z becomes substantially zero is detected, and the progress of the crosslinking reaction of the uncrosslinked rubber is measured as the completion of the crosslinking reaction of the laminated rubber 13. However, if the laminated rubber bearing 10 is made of the same material and has the same shape, size, and structure, the above measurement is repeated a plurality of times to obtain the electrical impedance Z1 from this, and thereafter, the rubber of the same material is used. In the case of obtaining a laminated rubber bearing having the same shape, size and structure, the time change rate δZ from the electric impedance Z1 or substantially zero with the electric impedance Z1.
The completion of the crosslinking reaction of the rubber may be measured from / δt.

In the above example, the progress state of the crosslinking reaction of the uncrosslinked rubber is set to the completion state of the crosslinking reaction. However, at least one of the specific value of the electrical impedance and the specific value of the time change rate δZ / δt is set. You may make it measure a crosslinking reaction progress state of an uncrosslinked rubber by linking a value and a crosslinking reaction progress state in the middle.

[0013]

As described above, according to the present invention, the end point of the rubber cross-linking reaction can be determined very clearly, and the temperature rising curve is changed, or the product shape is different. Even if there is, the completion of the rubber crosslinking reaction can be determined very easily, and the progress of the crosslinking reaction in the middle of the uncrosslinked rubber can be measured.

[0014]

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a laminated rubber bearing or the like used in an example of the present invention.

FIG. 2 is a diagram showing a measurement result of a relationship between elapsed time and impedance between electrodes.

[Explanation of symbols]

 10 Laminated Rubber Bearing 13 Laminated Rubber 14, 15, 16, 17, 18 Internal Steel Plate

Front page continuation (72) Inventor Ikuo Shimoda 8 Kirihara Town, Fujisawa City, Kanagawa Prefecture Oiles Industrial Co., Ltd. Fujisawa Plant (72) Inventor Masayoshi Ikenaga 8 Kirihara Town, Fujisawa Kanagawa Prefecture Oles Corp. Fujisawa Plant (72) Inventor Kosuke Sasaki 8 Kirihara-cho, Fujisawa-shi, Kanagawa OILES Fujisawa Plant

Claims (7)

[Claims] 1. A method of measuring the state of progress of a crosslinking reaction of an uncrosslinked rubber by detecting an electrical characteristic value of the rubber. 2. The method according to claim 1, wherein impedance is detected as the electrical characteristic value. 3. The method according to claim 2, wherein the completion of crosslinking of the uncrosslinked rubber is measured by detecting that the impedance reaches a steady value. 4. The method according to claim 2, wherein the completion of crosslinking of the uncrosslinked rubber is measured by detecting that the rate of change of impedance with time reaches substantially zero. 5. The method according to claim 1, wherein the uncrosslinked rubber is a rubber for a laminated rubber bearing. 6. The method according to claim 5, wherein the electrical characteristic value of the rubber of the laminated rubber bearing is detected by using any one of a pair of internal steel sheets of the plurality of internal steel sheets of the laminated rubber bearing as an electrode. 7. The method according to claim 6, wherein a high frequency voltage is applied to the pair of inner steel plates to detect an electrical characteristic value.