JPS6025735B2 - Closed type curing degree measuring device for viscoelastic substances - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an apparatus for measuring dynamic viscoelastic properties during the curing process of a vulcanizable rubber-like material or a curable resin-like material in a manner that does not include mechanical errors caused by friction.

In order to test the physical properties of rubber, resin, etc. during the curing process, traditionally a large number of test pieces were prepared with different curing times, and then these were individually tested to determine their physical properties, curing speed, etc. The method used was to measure the time it takes to reach an appropriate curing time.

In this method, a large number of test pieces are prepared and tested, which wastes time and money, is inefficient, and lacks prompt response. Subsequently, various measuring devices were developed that record changes in mechanical properties as the specimen hardens as the degree of hardening by continuously measuring the resistance force while applying oscillatory shear deformation to a single specimen. Ta. A hardening degree measuring device must reproduce the state of a viscoelastic substance in a processing machine such as a vulcanization press, and measure the mechanical properties of a sample while minimizing the effects of causes other than the sample.

To this end, the sample chamber must be of a sealed structure, and by sealing it, it is possible to detect and measure the stress without creating extra friction or other resistance on the sample itself or on the sample's stress detection mechanism. is important. This mutually holds true 1
There is no known hardening degree measuring device that simultaneously satisfies the hardness requirements. The structure of the sample chamber of currently known measurement devices is '1' open type, '2' closed type where the rotor is wrapped in the sample, and {3' half type where one side of the sample chamber also serves as the rotor. Closed type, ■ One side of the sample chamber also serves as a rotor, and the gap between the fixed side of the sample chamber and the rotor is sealed with pressurized air.

The measuring devices having sample chambers {1} to '41 described above each have the following drawbacks.

[11 sample chambers are non-sealed.

Since the heated sample comes into contact with the outside air in a significantly foamed state, differences in reaction conditions cause errors in the curing speed. [In the sample chamber No. 21, the discontinuous decrease in frictional resistance and stress due to slippage and local breakage of the sample that entered the gap between the rotor shaft and the bearing causes non-negligible errors in measurement.

Furthermore, heat leakage through the rotor legs is large, and the temperature rise during sample filling is slow, resulting in thermal errors. In the legs, sample slipping and local breakage occur at the boundary between the fixed side and the drive side of the sample chamber, similar to '2}, which causes errors in measurement.

Moreover, since there is no way to predict the magnitude of this type of error, it is impossible to correct it after measurement. In '4}, the resistance of the seal part for keeping the sample chamber airtight is large, and the mechanism for pressurizing the sample chamber is complicated. Furthermore, since the bearing receives the pressure generated in the sealed sample chamber, resistance in the rotational direction increases, reducing the accuracy of detecting stress in the rotational direction generated in the sample. Furthermore, in order to reduce the influence of pressure in the axial direction of the rotor, a complex bearing structure is required. As explained above, conventional hardening degree measuring devices have drawbacks such as sealing the sample chamber, generating excessive strain on the sample, and detection mechanism for resistance force to shear strain applied to the sample, and are not highly accurate. It was difficult to measure the degree of cure.

The present invention has been made as a result of intensive research aimed at solving the above-mentioned drawbacks of conventional hardness measuring devices, and as a result has succeeded in developing a closed-type hardening degree measuring device with a simple structure and high accuracy.

An object of the present invention is to provide a hardening degree measuring device for a viscoelastic material that measures the resistance force while applying an oscillatory linear return shear strain to a sample filled in a sample chamber. Provided is a closed-type hardening degree measuring device for a viscoelastic substance, characterized in that a portion is provided to connect the portions with an elastic material, and a bearing portion capable of rotating and vibrating supports the driving side without generating frictional torque. It is in.

That is, the device of the present invention includes an outer cylinder (die), an inner cylinder (die) forming a sample chamber between the outer cylinder, and a device that swings relative to either the outer cylinder or the inner cylinder. In a closed type hardening degree measuring device for a lees elastic material, which has a mechanism for imparting motion and a mechanism for measuring torque applied to either the outer cylinder or the inner cylinder by the mechanism, (a) An elastic body that connects the boundary between the (a) and the outer pulp without frictional resistance, and an elastic body that connects the axial pressure of the mechanism that measures the uniform torque on the extension line of the center ball. The present invention provides a closed-type curing degree measuring device for viscoelastic substances, characterized by having a mechanism that uses a torsion spring or a thin-walled hollow cylinder to support pressure in the ball direction without turning it into frictional resistance in the rotational direction. .

According to the device of the present invention, (a) By using an elastic material at the boundary between the fixed side and the driving side of the sample chamber, resistance due to excessive strain of the sample that occurs in this part of the sample chamber is not generated. , {o}A bearing with a hanging structure that does not generate friction torque is used as the support mechanism for the shaft connected to the cylinder (die) on the side where the viscoelasticity of the sample is measured, so it is not affected by the pressure in the sample chamber. It has the characteristic of being able to reproducibly and purely obtain a degree of hardening that represents low viscoelastic drag of the sample.

Furthermore, according to the device of the present invention, since the sample chamber is a closed type, the conditions during curing are close to those in a mold in an actual processing machine, and the measurement is performed using a vibration method that repeats a small shear strain. Therefore, the degree of hardening can be measured during the entire curing process (although the sample chamber has a sealed structure, the rotor is not surrounded by the sample, so errors due to heat leakage and thermal delays are small; The elastic material that connects the boundary between the stationary side and the drive side of the sample chamber, which is characteristically used in the present invention, is a heat-resistant elastic material such as silicone rubber, etc. Fluororubber, acrylic rubber, nitrile rubber, etc. are used.

The elastic material is annular and has a thickness of at least 0
．． It is used in a range of 5 or more ribs, preferably 2 to 10 ribs. The cross-sectional structure of the elastic material can be arbitrarily selected depending on the structure of the sample chamber. In addition, as a bearing capable of rotational vibration that supports the pressure of the sample chamber without generating friction torque, which is characteristically used in conjunction with an elastic material in the present invention, a suspension device using a torsion spring or a thin-walled hollow cylinder can be used. is used.

The torque meter used in the device of the present invention may be mounted on a torsion spring or a thin hollow cylinder coaxial with the rotor shaft, but is preferably mounted on an arm that rotates and vibrates the rotor shaft.

Next, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is an explanatory diagram showing the entire apparatus with the sample chamber closed.

The sample chamber 1 includes a truncated conical recess or outer cylinder (die) 3 provided in the center of a lower heating plate 2, and an upper heating plate 5 fixed to a mounting frame 4.
It is formed at the center between an outer cylinder 3 and a truncated conical inner cylinder (die) 6 coaxially stratified. An elastic material 7 and a mounting fitting 8 for the elastic material 7 are inserted at the boundary between the inner cylinder (die) 6 and the outer cylinder 3. The mounting bracket 8 is screwed to the upper heating plate 6, and the elastic material 7 can be replaced using this screw (not shown).
This can be easily done by removing the . The attachment and detachment of the sample is carried out by operating the pressure in the air cylinder 9 using an air valve (not shown) and lowering the lower heating plate 2 relative to the mounting frame 4. When lower heating plate 2 is lowered, the inner and outer cylinders are sufficiently separated,
There will be enough space between the upper and lower heating plates to easily perform various necessary operations. The inner tube 6 serves as a kind of rotor, but unlike some types of follower devices where the rotor is wrapped around the sample, it is easy to attach and detach the sample. 10 is a groove provided on the upper surface of the lower heating plate 2.

The surfaces of the inner tube 6 and the outer tube 3 are provided with four small irregularities over the entire surface of the sample chamber to prevent the sample from slipping. One of the characteristics of the sample chamber of the present invention is that there are no parts in the entire sample chamber that force excessive sample strain that may cause sample slippage or local breakage. In conventional devices, the area where slipping occurs is mainly at the boundary area where the hard walls on the drive side and the fixed side are adjacent to each other, but in the present invention, this area is connected with an elastic material, so that it acts as a kind of elastic wall surface together with the sample. Because of the deformation, the strain within the sample is naturally and continuously distributed along the elastic wall surface, and no large concentrated strain occurs locally. The inner cylinder 6 has an inner cylinder drive shaft 11 and an inner cylinder shaft support frame 1.
2, a crank arm 14 fixed to the mounting frame 4 via a torsion spring 13 and connected to the upper end of the inner cylinder drive shaft 11;
15, an eccentric shaft 16, and a motor 18 via a reducer 17.
As a result, the inner cylinder 6 is driven to swing around its axis.

The swing angle amplitude of the inner cylinder 6 is set to a small value of about 5° or less, but its magnitude can be changed by replacing the eccentric shaft 16. The torque required to drive the inner cylinder 6 is converted into an electric signal by a load cell type torque meter 19 provided in the middle of the crank arm 15, and is recorded on two recording devices. The high pressure applied when filling the sample chamber 1 with the sample remains in the sample while decreasing somewhat during measurement.
, and does not act on the torque meter 19. When supporting such an axial load (thrust load) on a rotating shaft, a conventionally well-known method is to use a commercially available thrust bearing such as a thrust type ball bearing, but this method does not support the thrust load inside the bearing. A corresponding frictional resistance torque is generated, and this frictional torque is mixed into the detected amount of the torque meter as an error of a size that cannot be ignored.

Since this error complexly and significantly changes depending on the sample pressure, it is not possible to measure only the error in advance and then correct it. In comparison, the thrust bearing mechanism using a torsion spring of the present invention does not have a frictional part. The torque detected by the torque meter 19 is mainly the sum of the three torsional resistance forces of the sample, the elastic material 7, and the torsion spring 13, but since the torsion resistance of the elastic material and the torsion spring do not change depending on the sample pressure, By driving the device, the sum of the two is measured as a so-called empty torque, and by subtracting it using an appropriate method from the measured torque after filling the sample, only the torsional resistance force of the sample can be determined. During measurement, inner cylinder 6
A radial bearing is used between the upper heating plate 5 and the inner cylinder drive shaft 11 in order to keep the outer cylinder 3 and the outer cylinder 3 coaxial with each other and to drive the inner cylinder smoothly. In this case, it is preferable to use a cylindrical sliding bearing 21 processed with a fluororesin rather than a normal ball bearing in the sense that heat conduction can be improved. The coefficient of friction of a sliding bearing is larger than that of a ball bearing, and the bearing friction increases due to the lateral load caused by the deviation of the sample during filling, but this lateral load is minute compared to the thrust load mentioned above. , and the bearing friction described above is practically negligible since it decreases rapidly over time and is short at the beginning of the measurement. The upper and lower heating plates are each heated by two band-shaped electric heaters 22 wrapped around their outer circumferential surfaces, and a temperature controller (not shown) performs a predetermined measurement via a temperature sensor 23 embedded inside each heating plate. maintained at temperature. As the temperature sensor and temperature controller, either a thermocouple type or a platinum resistance type which is well known in the art can be used.
The temperature distribution inside the heating plate can be made sufficiently small by selecting the material of the heating plate as a good conductor of heat, such as aluminum alloy, and insulating the outer peripheral surface with a suitable heat insulating material. Although the inner cylinder 6 is not directly heated, the material of the inner cylinder drive shaft 11 is selected to be a good conductor of heat, and the contact area with the sliding bearing 21 is widened.
By using a hard insulating material such as asbestos (not shown) at the connection part with the inner cylinder shaft support frame 12, the temperature difference between the inner cylinder 6 and the upper and lower heating plates can be kept small enough to be ignored. . In this way, the sample filled in the sample chamber is heated from both sides, so it quickly reaches the specified temperature.
Errors due to thermal delays during this time can be kept to a minimum. To measure the degree of hardening of a viscoelastic substance using the apparatus of the present invention, a sample with a volume larger than the volume inside the sample chamber is placed in the sample chamber 1, and the upper and lower heating plates 2 are adjusted to a predetermined temperature. , 5 close.

The excess sample flows out through the groove 101 formed in the lower heating plate 2. When the inner cylinder 6 is reciprocally rotated at a constant angle by the driving device, the stress corresponding to the viscosity of the sample is recorded by the torque meter 19 and the recording device 2. As shown in Figure 1, the shape actually drawn by two recording devices is a symmetrical continuous wave curve with a gently increasing amplitude. For convenience, the depiction of the entire waveform is omitted and only one side of the symmetrical amplitude locus is drawn. In other words, in Figure 3, the vertical axis represents the torque amplitude, and the horizontal axis is the symmetrical axis of the original figure and represents the elapsed time. represents.

The symbol to represents the time when the sample was filled, and the curve to the left represents the empty torque described above. Curve A in the figure is data measured using the device of the present invention using a sample of a compound containing styrene-butadiene rubber and carbon black as main components and a commonly used vulcanizing agent, etc.; This is data when a commercially available thrust type ball bearing is used instead of the torsion spring bearing mechanism. In the empty torque section, there is no thrust load, so the friction of the ball bearing is small, and the curved opening falls below curve A by approximately the equivalent of the torque of the torsion spring, but after filling the sample, only the sample resistance torque is added at curve A. On the other hand, at the entrance of a curve, the frictional resistance of the bearing due to the large thrust load is added to that, so a torque that exceeds the curve A is observed. This error torque included in the curve opening changes sensitively and complexly depending on the viscosity of the sample and the amount of preparation, so there is no way to correct it, and it also adversely affects the reproducibility of measurements. In comparison, in the case of {i}, good reproducibility can be easily obtained without special precautions such as keeping the charging amount constant, and the correct hardening curve corresponding only to the hardening of the sample can be used to calculate the empty torque value. It can be obtained by simply drawing a diamond. In Fig. 4, curve C is a hardening curve obtained by subtracting the idle torque produced by the device of the present invention, and curve 2 is a hardening curve obtained by subtracting the dry torque produced by the device of the present invention.
The hardening curve and curve tree are data obtained from an oscillating desk rheometer (see Samurai Ko Sho 42-16035), which is a known closed-structure device with a rotor.

For the curves C and E, the operation of subtracting the idle torque is meaningless due to the above-mentioned reason, so the axis of symmetry of the original figure is used as the horizontal axis. In addition, the scale of the vertical axis in Figure 4 is such that the difference between the minimum value of torque amplitude before vulcanization and the equilibrium value of torque amplitude in a fully vulcanized state is expressed as the same size on the diagram. A relative scale like this is used. Except for the rising portion of curve E, curves 2 and 2 are all located higher than curve C because extra frictional torque is added to those curves. Also, the reason why the vulcanization of curve 2 is apparently faster and the vulcanization of curve E is slower than that of curve C is because vulcanization in curve 2 is incompletely sealed, so the vulcanization is affected by outside air through the gap around the die. The main reason was that the speed was increased; in the case of E, the temperature difference between the die and the sample caused by constant heat leakage through the rotor leg apparently decreased the vulcanization rate. I think this is the main cause. A modification of the embodiment shown in FIG. 1 is shown in FIG. Figure 1 shows an example of a structure in which the torque required for driving is detected by driving the inner cylinder 6 via a torque detection part, but the embodiment shown in Figure 5 separates the drive side and torque detection side. Regarding the structure. Portions in FIG. 5 that are similar to those in FIG. 1 are designated by the same reference numerals. The sample chamber 1 includes a disk-shaped upper die 24 (corresponding to the inner cylinder 6 in FIG. 1) fixed to the torque detection shaft 11', and a disk-shaped lower die 25 (corresponding to the inner cylinder 6 in FIG. 1) fixed to the drive shaft 26. (corresponding to the outer cylinder 3 in FIG. It is a disk-shaped space surrounded by two connecting upper and lower ring-shaped elastic materials 7. When the drive whip 26 is vibrated by the crank arms 23, 30', the lower die 25 vibrates, and this vibration is transmitted to the upper die 24 through the sample filled in the sample chamber 1, causing the detection shaft 11' and the crank to vibrate. It is transmitted to the load cell 19 through the arms 14 and 15. The other end of the load cell 19 is fixed to the upper heating plate 5 by a suitable fixture. driving wisteria 2
6 is preferably supported by sliding bearings 27 and 28 made of fluororesin for the same reason as mentioned above. In this structure, the effect of the torsional rigidity of the elastic material 7 on the detected torque is small, so there is an advantage that an elastic material having a stronger shape can be used compared to the structure shown in FIG. 1.

[Brief explanation of drawings]

Fig. 1 is an explanatory diagram of the device of the present invention, Fig. 2 is an explanatory diagram showing the relationship between the driving part for vibrating the measurement part and the torque detection part, and Fig. 3 is an explanatory diagram showing the relationship between the driving part for vibrating the measuring part and the torque detection part. Fig. 4 is a diagram showing an example of measurement using a conventional thrust type ball bearing, and Fig. 4 is a diagram showing an example of measurement of the degree of hardening of the same sample using the device of the present invention and the conventional device. The figure shows a modification of the embodiment shown in FIG. 1...Sample chamber, 2...Lower heating plate, 3...
Outer cylinder, 4...Mounting frame, 5...Top heating plate,
6... Inner cylinder, 7... Elastic material, 8...
...Mounting bracket, 9...Air cylinder, 10.
... Concave groove, 11 ... Inner cylinder drive shaft, 12.
...Inner cylinder shaft support frame, 13 ...Torsion spring, 1
4, 15... Crank arm, 16...
・Eccentric shaft, 17...Reducer, 18...
Motor, 19...Torque meter, 20...
・Recording device, 21...Sliding bearing, 22...
... Heater, 23 ... Temperature sensor. Tsutomu l figure Atsushi Z figure 3 Kyo figure 4 Tsutomu figure 5

Claims (1)

[Claims] 1 an outer cylinder, an inner cylinder forming a sample chamber between the outer cylinder, a mechanism that provides relative rocking motion to either the outer cylinder or the inner cylinder, and a mechanism that provides a relative rocking motion to either the outer cylinder or the inner cylinder; In a closed-type curing degree measuring device for a viscoelastic material having a mechanism for measuring torque applied to either one of a cylinder and an inner cylinder, (a) the boundary between the inner cylinder and the outer cylinder is connected without frictional resistance. and (b) a torsion spring or thin-walled hollow cylinder connected and attached on an extension of the central axis to convert the axial pressure of the torque measuring mechanism into frictional resistance in the rotational direction. 1. A device for measuring the degree of hardening of a viscoelastic substance, characterized by comprising a mechanism for supporting the degree of hardening of a viscoelastic substance.