JPH0552733A - Dispersion evaluating method for sulfur - Google Patents

Abstract

PURPOSE:To instantaneously and simply measure the dispersion condition of sulfur with high accuracy by irradiating unvulcanized milled rubber with X rays including the wavelength which causes the absorption of sulfur element, photographing the fluoroscopic image, and analyzing the image. CONSTITUTION:An X-ray tube 3 facing the up and down directions is provided at the halfway of a conveyer 2 for conveying an unvulcanized milled rubber 1. An image sensing device 5 for the fluoroscopic image of X rays is provided and connected to an image processing device 4. These devices perform the photographing and the image processing at every specified time of at every specified length. The sample of rubber composition having the different kneading condition is set on an X-ray apparatus, which has the magnified fluoroscopic state and has the wavelengths by which the absorption of a sulfur element is generated. Then, the X-ray fluoroscopic image is picked up, and the area of the sulfur particles is obtained. As a result, the dispersion of the sulfur progesses with the increase in milling time, and the sulfur particles are decreased. Namely, the adequacy of the dispersion condition of the sulfur can be readily evaluated based on the particle area.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sulfur dispersion evaluation method for determining the dispersion state of sulfur, which is a vulcanizing agent widely used in the rubber industry, and more specifically, to an unvulcanized kneaded rubber sheet. The present invention relates to improvement of a sulfur dispersion evaluation method for discriminating the dispersion state of existing compounded sulfur.

[0002]

2. Description of the Related Art Conventionally, there are few methods for evaluating the dispersion state of compounded sulfur in an unvulcanized and kneaded rubber sheet, and a method has been proposed in which a rubber sheet is slightly attached to a copper plate to cause a reaction to be discriminated. (JP-A-62-2156).

[0003]

However, JP-A-62-2 is used.
No. 156 is a device for supplying a copper plate, a device for mirror-polishing the surface of the copper plate, a device for heating the mirror-finished surface of the copper plate, and a device for press-supporting the kneaded rubber on the surface of the heated copper plate. A device for reacting the compounded sulfur in the kneaded rubber with copper on the surface of the copper plate to form a trace of a sulfur reaction on the copper surface, a device for removing the kneaded rubber supported under pressure from the copper plate surface, and the copper plate It is composed of a device for observing traces of the sulfur reaction on the surface and discriminating whether or not the dispersion of the compounded sulfur in the kneaded rubber is good, so that the device itself is large and complicated, but the measurement accuracy is not always sufficient. However, there was a problem of lack of practicality.

In the first place, in order to control the process of sulfur dispersion in a factory, an apparatus capable of instantaneous measurement is required, and the method of visual observation or chemical reaction is not appropriate.

An object of the present invention is to provide a method for evaluating dispersion of sulfur which has good measurement accuracy and can be measured simply and quickly.

[0006]

By the way, when sulfur which is frequently used in the rubber industry is examined, sulfur is generally a powder, and as the rubber is kneaded, it is subdivided and the particle size is reduced. Therefore, the smaller the particle size, the better the kneading. However, since it is better to shorten the kneading time as much as possible in order to increase the production efficiency, it is considered that the kneading is completed when the particles have a particle size below a certain level. The level differs depending on the field of each rubber industry, but it is generally several microns or more.

On the other hand, sulfur has an X-ray absorption wavelength at 5.3 angstroms of the atomic K shell, while rubber, carbon, oil, etc. have absorption wavelengths at 44 angstroms in the carbon element, and Zinc white has an absorption wavelength of 23.7 angstroms in oxygen element, and zinc has an absorption wavelength of 1.4 angstroms, and all of these other compounding components absorb in a region apart from sulfur,
It is considered that the presence of sulfur in the rubber composition can be separately detected by utilizing such X-ray irradiation. Therefore, in view of the above points, the present invention irradiates an unvulcanized kneaded rubber sheet with X-rays containing a wavelength at which absorption of elemental sulfur occurs, and when a projection photograph thereof is taken, the particle size and distribution state are X-rays. Since it can be understood from the absorption difference of, as a dispersion evaluation method of sulfur,
We have developed a method to quantify and quantify particles of a certain level or more by image processing. That is, this invention is
X containing a wavelength that causes absorption of elemental sulfur in unvulcanized kneaded rubber
It is a sulfur dispersion evaluation method characterized in that the state of sulfur dispersion is evaluated by irradiating a line, capturing a fluoroscopic image, and analyzing the image.

Regarding the size of the fluoroscopic image,
Although it depends on the level of the particle size used as the inspection standard, this method can process a full-size or magnified perspective image of 1 to 100 times.

On the other hand, when irradiating with X-rays, it is necessary to set an unvulcanized kneaded rubber in an X-ray fluoroscopic image capturing device. As a sampling method in this case, for example, an unvulcanized kneaded rubber sheet is used. It is possible to employ a simple method in which a circular piece is punched out and the piece is passed through a photographing device and photographed. A method of continuous evaluation is also conceivable. For example, as shown in the drawing, a conveyor 2 that conveys an unvulcanized kneaded rubber sheet 1
An X-ray tube 3 facing each other in the vertical direction and an X-ray fluoroscopic imaging device 5 connected to an image processing device 4 are installed on the way,
There is a method of shooting and image processing at regular time intervals or constant length intervals. It should be noted that in any of the methods, it is desirable to measure the rubber thickness as constant as possible, but the present invention is not particularly limited to any of the methods.

[0010]

Therefore, the present invention is a method of irradiating an X-ray containing a wavelength that causes absorption of elemental sulfur, taking a fluoroscopic image, and performing image analysis to evaluate it. Can be measured.

[0011]

Example A rubber composition blended under the conditions shown in Table 1 was mixed in a Banbury mixer under the conditions shown in the same table to give a thickness of 7
An unvulcanized kneaded rubber sheet was prepared. For comparison, a non-blended example of sulfur was also prepared.

Next, a circular sample having a diameter of 30 mm was punched out from these rubber sheets with a dumbbell, and this was set in an X-ray apparatus having a magnifying see-through function and containing a wavelength of 5.3 angstrom at which absorption of elemental sulfur occurs. , A 40 × X-ray fluoroscopic image was taken to determine the area of the particles seen in this image.

Table 1 shows the results.

[0014]

[Table 1]

From Table 1, it can be understood that in Comparative Examples 1 to 3 in which sulfur is not added, almost no sulfur particles are detected, while in Examples 1 and 2 in which sulfur is added, the sulfur particles can be measured as the particle area. In addition, it is generally known that mixing of zinc white improves the kneading to some extent, but the difference in area value between Examples 1 and 2 well expresses the correspondence relationship in this respect. Further, it is recognized that the difference in the mixing state due to the difference in the mixing time also shows a good correspondence in the area value of the sulfur particles between Example 2 and Example 3.

Next, the compounded rubber of the following compound A is mixed with a Banbury mixer, and the compounded rubber and the compound B described below are mixed.
The vulcanizing agent of No. 1 was further kneaded with a roll under the kneading conditions shown in Table 2, and the relationship between the actual kneading time and the area of the sulfur particles appearing in the X-ray transparent image was examined. The vulcanizing agent of the following B is compounded with the polymer content in the compounded rubber of the compound A as 100.

A compound Natural rubber 50 parts SBR1500 50 parts Carbon 50 parts Zinc white 5 parts Stearic acid 2 parts Oil 10 parts Anti-aging agent (Santflex 13) 2 parts B Vulcanizing agent accelerator (NOBS) 1 part 20% oil Treated insoluble sulfur 4 parts The kneading conditions were 4 conditions as shown in Table 2. For sampling, make a batch of rubber under each condition into a 5 mm thick rubber sheet,
A circular sample having a diameter of 50 cm was punched out with a dumbbell. Next, this sample is set in an X-ray device having a magnifying fluoroscopic function and a wavelength at which absorption of elemental sulfur occurs, and a 30 times X-ray fluoroscopic image is taken to determine the area of particles seen in this image. It was

[0018]

[Table 2]

As shown in Table 2, it can be seen that as the kneading time is increased, the dispersion of sulfur progresses, and the number of sulfur particles appearing in the 30-fold X-ray fluoroscopic image is reduced.

As described above, in the method using the X-ray fluoroscopic image, the kneading state can be determined by measuring the particle area appearing on the image. Therefore, from the kneading state desired by each rubber industry, the X-ray can be changed. By determining the area of particles appearing on the fluoroscopic image and using this as the sulfur dispersion standard, it is possible to easily evaluate the suitability of the sulfur dispersion state. Therefore, if the evaluation and the kneading operation are linked, the optimum kneading operation can be automated. The present invention is not limited to the above embodiment.

[0021]

As described above, according to the present invention, the X-ray absorption of elemental sulfur is in a region relatively distant from other blending components, and the generally accepted particle size level in the kneading state is several microns or more. We provided an evaluation method of irradiating an unvulcanized rubber, which is the object of measurement, with X-rays containing a wavelength that causes absorption of elemental sulfur, photographing a fluoroscopic image of the unvulcanized rubber, and analyzing the image. Therefore, irradiate X-rays, take a fluoroscopic image,
Since this is an image analysis method, it can be evaluated instantly and easily with high accuracy, and the level to be evaluated can be set and changed as appropriate, which is extremely useful for various rubber industry fields.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing an example of a sulfur dispersion evaluation apparatus.

[Explanation of symbols]

 1 rubber sheet 2 conveyor 3 X-ray tube 4 image processing device 5 imaging device

Claims (1)

[Claims] 1. A dispersion state of sulfur in unvulcanized rubber by irradiating the unvulcanized rubber with X-rays containing a wavelength causing absorption of elemental sulfur, capturing a perspective image of the image, and analyzing the image. A method for evaluating the dispersion of sulfur, which is characterized by evaluating