JPH0340686B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention relates to an improvement in a method for controlling a rubber vulcanization process. (Prior Art) Conventionally, a so-called vulcanization totalizer using the Arrhenius equation has been used as a device for detecting the degree of vulcanization of rubber during vulcanization. In such a device, the activation energy and reference temperature for one vulcanization reaction are set in advance, and the actual temperature-time history during vulcanization is converted into an equivalent vulcanization time t ₀ at the set reference temperature T ₀ . It is possible to output a signal to the vulcanizer when a preset equivalent vulcanization time t ₀ is reached. Incidentally, the conversion to the equivalent vulcanization time t ₀ is based on the following principle based on the Arrhenius equation. The Arrhenius equation is well known to express the rate of chemical reactions. Here, k: reaction rate constant A: frequency factor E: activation energy R: gas constant T: reaction temperature If the reaction rate constant at reaction temperature T ₀ is k ₀ , then Therefore, the ratio of reaction rate constants k/k ₀ is becomes. Therefore, if equation (2) is integrated over the reaction time t at T, equation (3) is obtained. The value t ₀ obtained thereby represents how many times the reaction amount per unit time is at a certain predetermined temperature T ₀ (hereinafter referred to as reference temperature), and is generally called the equivalent reaction time. (Problem to be solved by the invention) However, the vulcanization reaction does not have a single reaction mechanism;
Although the activation energy changes as vulcanization progresses, one activation energy determined for one degree of vulcanization is applied to the entire reaction process, so the equivalent vulcanization time t ₀ The accuracy of conversion is poor, and this tendency is particularly pronounced for values at degrees of vulcanization that are far from the degree of vulcanization for which the activation energy was determined. Furthermore, although the actual degree of vulcanization does not change linearly with the equivalent vulcanization time t ₀ , the degree of vulcanization is said to be proportional to the equivalent vulcanization time t ₀ , and as mentioned above, the equivalent vulcanization Since the accuracy of conversion to time t ₀ is low, the accuracy of the degree of vulcanization is also low. Therefore, in order to solve such problems, the vulcanization reaction is divided into an induction reaction period and a vulcanization reaction period, and two activation energies corresponding to each reaction period are used to perform vulcanization at a certain temperature. The time of the induction reaction period is calculated, and when the equivalent vulcanization time _t0 exceeds this, vulcanization progresses due to an Arrhenius type chemical reaction, and the degree of vulcanization is calculated, and when this reaches a certain value, a signal is generated. (Refer to Japanese Patent Publication No. 57-50662), but even within the vulcanization reaction period, for example, 10%, 50%, 90%
Since some rubber compounds have significantly different activation energy determined from the % reaction point, the conversion accuracy to the equivalent vulcanization time t ₀ is insufficient, and the equivalent degree of vulcanization within the vulcanization reaction period is insufficient. The functional relationship with the vulcanization time t ₀ differs depending on the type of rubber compound.Especially when detecting and controlling when the surface layer becomes over-vulcanized during vulcanization of thick materials, it is important to check for re-vulcanization, deterioration, hardening, etc. occurs and cannot be expressed by a fixed function, and the accuracy of conversion to equivalent vulcanization time t ₀ is low, so there is a problem that the accuracy of the degree of vulcanization is insufficient. The present invention has been developed by treating the activation energy of the vulcanization reaction as a function of the equivalent vulcanization time at a reference temperature, and the degree of vulcanization as a function of the equivalent vulcanization time at the reference temperature. An object of the present invention is to provide a method for controlling a rubber vulcanization process in which the degree of vulcanization of rubber is detected with high precision and the degree of vulcanization is controlled according to the degree of vulcanization. (Means for Solving the Problems) The present invention is a method for continuously detecting and controlling the degree of vulcanization in a rubber vulcanization process, which is based on the vulcanization time at a reference temperature and the activation energy of the vulcanization reaction. The first step is to determine the activation energy E at the cumulative equivalent vulcanization time t ₀ as a continuous function of the cumulative equivalent vulcanization time t ₀ based on the relationship, and to detect the rubber temperature during vulcanization using a temperature measuring means. Using the activation energy according to the continuous function determined in the first step, the equivalent vulcanization time Δt ₀ and its integration at the reference temperature for each intake temperature are calculated based on the Arrhenius equation. The second step is to calculate the cumulative equivalent vulcanization time _t0 , which is the value, and the cumulative equivalent vulcanization time t calculated in the second step based on the relationship between the vulcanization time and the degree of vulcanization at the reference temperature. The third step is to calculate the degree of vulcanization x at ₀ , and the cumulative equivalent vulcanization time _t0 or degree of vulcanization
The fourth step is to compare and determine whether or not the cumulative equivalent vulcanization time t _pC and the degree of vulcanization x _c are greater than or equal to a preset cumulative equivalent vulcanization time t pC and to determine whether the vulcanization process is complete. (Function) As shown in FIG. 1, in step _S1 , the rubber temperature during vulcanization is detected and taken in at intervals of a predetermined time Δt. Let T _(i) be the temperature at time t _(i) . Subsequently, it is converted for calculation in step _S2 , and then
In _S3 , Δt _0(i) , which is equivalent to Δt, is calculated based on the Arrhenius equation. Thereafter, in step _S4 , the integrated value of Δt _0(i) , that is, the equivalent vulcanization time t _0(i) is calculated. t _0(i) = _i 〓 ^j=1 △t _0(j) = T _0(i-1) + △t _0(i) Meanwhile, in step _S5 , the equivalent vulcanization time t ₀ and activation energy E The relationship (set data) is input, and in step _S6 , the activation energy E _{( i-1) for the equivalent vulcanization time t 0 (i-} 1) is calculated. That is, continuous function E=
f _1(t0) (polynomial regression equation) is determined. Also, in step _S7 , input the relationship (set data) between the degree of vulcanization x at the reference temperature _T0 and the time _t0 ,
In step _S8 , the continuous function x=f _{2 (t0)} is determined. In addition, the continuous function E in steps S ₆ and S ₈
Instead of determining =f _{1 (t0)} and x = f _{2 (t0)} , an interpolation method such as a spline method or a Lagrange method can also be used. Alternatively, E=f _1(t0) and x=f _2(t0) may be determined separately in advance, and only the regression coefficients thereof may be input at the time of measurement. Next, in step _S9 , the degree of vulcanization x(i ₎ corresponding to the equivalent vulcanization time _t0(i) is calculated, and in step _S10 , the degree of vulcanization _xC which requires a preset signal transmission and step S ₉
The degree of vulcanization x _(i) calculated in step _S11 is compared and determined, and if x _(i) ≧ _xC , a signal is transmitted in step _S12 . Further, in step _S10 , the equivalent vulcanization time _t0C required for signal generation is set and input, and in step _S11 , a comparison is made to determine whether t0 _(i) ≧ _t0C , and _t0(i) ≧ The signal may be transmitted in step _S12 when t _0C . This signal transmission confirms that the vulcanization process has been completed. Furthermore, in step _S13 , t _(i) , T _(i) , t _{0 (i)} , and x _(i) are output and displayed. Note that t _{0 (i=0)} = 0, E _{(i = 0)} = f _{2 (0)} , and is applied only to the first operation. i is a number indicating the number of times the temperature is taken. (Example) Hereinafter, an example of the present invention will be described. An example of an apparatus for accomplishing the above method is shown in FIG. 1 is a temperature sensor that detects the rubber temperature during vulcanization, 2 is a means (linearizer) for linearizing the electrical signal from temperature sensor 1 and converting the power level, 3 is an A/D converter, and 4 is input to the CPU 5. It is an I/O unit. CPU5 is the activation energy E _(i-1) vulcanization degree at equivalent vulcanization time t _{0 (i)}
Calculation of x _(i-1) , △t _0(i) , calculation of t _0(i ), t _0(i) and t _C , x _(i
) and
x Performs comparison operations with _C and performs display, output, and commands. Reference numeral 6 denotes a display unit, which outputs and displays t _(i) , T _(i) , t _{0 (i)} , and x _(i) on a display or, if necessary, on a printer. 7 is an input means such as a keyboard for inputting initial data, storing input data, calculating, displaying,
Enter the program for signal transmission. 8 is an external storage device for programs and data, which is installed as necessary. 9 is D/A
The converter converts digital signals sent from the CPU 5 to control the vulcanizer to the I/O unit 4.
and converts it into an analog signal A. Examples of the present invention will be described below. First, the rubber formulation is shown in Table 1.

[Table] Next, we measured using a cuylastometer,
Equivalent vulcanization time t ₀ at 160 °C, degree of vulcanization x, and 135
Table 2 shows the relationship between activation energy E set in the range of 190°C to 190°C.

【table】

[Table] In the case of * above, reversion occurred.
From Table 2, it can be seen that the activation energy E changes with the equivalent vulcanization time t ₀ and the degree of vulcanization x. Figure 3 shows the results obtained based on the method of the present invention at intervals of △t = 0.5 minutes for the temperature change with respect to the actual vulcanization time when can vulcanization was performed at 170°C. As shown in the figure. In this case, E _(i-1) , x _(i)
The calculation uses spline interpolation. Figure 4 shows the toluene swelling ratio and gel fraction of the sample obtained by press vulcanization of a 1 mm thick rubber sheet at the standard temperature, and the toluene swelling ratio and gel fraction of the sample vulcanized in the example. The results of determining the t−t ₀ relationship by comparison with the ratio are indicated by circles. In addition, as a comparative example, i) An example in which the activation energy E obtained at a degree of vulcanization x = 85% is applied to the entire vulcanization process is shown by the broken line, and the activation energy E in the induction period is
(17.4kcal/mole) and activation energy E during vulcanization
(19.1 cal/mole: the value when x = 85%) is applied to each period, and the dashed line shows an example.
Further, from FIGS. 4 and 5, the degree of vulcanization x is plotted against the equivalent vulcanization time t ₀ and the results are shown in FIG. In the figure, the thick line is the degree of vulcanization (F − F _nio ) / (F _nax − F _nio ) based on the torque value of the culastometer.
(F: Torque value, F _nio : Minimum torque value, F _nax : Maximum torque value). In FIG. 4, it can be seen that the values are extremely close to the actual measured values marked with a circle. Further, as a matter of course, the results shown in FIG. 6 are in good agreement with the results obtained by the cuelastomer vulcanization curve. In addition to the above, the present invention can also be applied to the control of chemical reaction processes where the relationship between the reaction rate constant and temperature is expressed by the Arrhenius equation during the entire reaction period or when a partial period is taken up. can. (Effects of the Invention) Since the present invention is constructed as described above, it is possible to control and manage the degree of vulcanization of rubber during vulcanization with extremely high accuracy, and the vulcanization conditions based on the degree of vulcanization (temperature , pressure, etc.) can be controlled accurately and automatically by connecting to the control section of the vulcanizer, and it is also possible to lower the level of temperature control accuracy of the vulcanizer.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing the flow of the control method of the present invention, Fig. 2 is a block diagram showing an example of a device for achieving the control method of the present invention, and Figs. 3 to 6 are graphs for respective embodiments. . 1...Temperature sensor, 5...CPU.

Claims (1)

[Scope of Claims] 1. A method for continuously detecting and controlling the degree of vulcanization in a rubber vulcanization process, which comprises: Equivalent vulcanization time t ₀
Integrate the activation energy E at the equivalent vulcanization time t ₀
The first step is to determine the temperature of the rubber during vulcanization as a continuous function of The second step is to calculate the equivalent vulcanization time Δt ₀ at the reference temperature for each intake temperature and the cumulative equivalent vulcanization time t ₀ which is the integrated value thereof based on the Arrhenius equation; and the vulcanization time at the reference temperature. a third step of calculating the degree of vulcanization x at the cumulative equivalent vulcanization time t ₀ calculated in the second step based on the relationship between the degree of vulcanization and the degree of vulcanization; The cumulative equivalent vulcanization time t ₀ or _{degree of} vulcanization x calculated in
A method for controlling a rubber vulcanization process, comprising a fourth step of comparing and determining whether or not the above is true, and determining whether the vulcanization process is completed.