Home >

Solution To Rubber Problem In Rubber Processing

2008/8/9 10:30:00 41763

??? 日本語 Fran?ais English 中文

In the process of rubber processing, some quality problems often occur, which hinders the smooth operation of production.

Because of the high cost of labor, the loss is considerable during the period of stoppage.

These problems can be solved if appropriate measures are taken for most of the same types of problems.

The following is the introduction of the solution to the author's experience.

The following is mainly about the treatment of quality problems such as uneven distribution of sulphur, spray frost and scorching.

1 sulfur is not evenly distributed and has pock (agglutination) phenomenon.

This is an old and new problem that our predecessors should solve.

Placing the stored sulphur on the cement board is not a good method from the angle of moisture-proof. It must be placed on the mat or backing plate. Sieving it before measuring is an effective way to prevent agglomeration. At this time, it is not necessary to use too thin sieves, with 40 eyes or 20 purposes, as long as it can break the caking in the powder sulfur.

In addition, when the amount of sulphur is less, it is better to add the sieve on the top side of the open mill, even if the screen is thicker.

In the traditional way, first put the sulfur on the plate and put it into the same volume of light calcium carbonate or white powder. After mixing evenly, add it on the open mill. Although this is a simple method, there is no better way to do it.

Here is a brief description of what is white powder, and put the shells and shells on the outside cement boards, let them blow in the sun and rain. After 2-3 years, the organic substances in them are decomposed and removed, and become white and calcium only substances. After crushing them, they are white powder. The powder can be used for rubber as well as other aspects.

In the rubber with a large number of hard clay, I do not know what causes the uneven distribution of sulfur.

Although many ideas have been devised, they have not worked.

We will cooperate with the mixer of the hard clay mother made of sulfur and other quality parts and mix it with the kneading machine. The mixing machine made by the company's self-made 40L kneading machine (rotate speed is about 30 rpm /m in) is mixed with about 1H.

The homemade sulphur masterbatch is used by the company itself.

However, once the rubber is used in the company, the dosage will be too large, and the variety needs to be specially processed.

Therefore, in addition to the rubber compound that has not yet had problems and the mixture that allows a small amount of sulfur particles, only the sulfur masterbatch is used only for the rubber that is really needed.

We use a rubber compound containing 100 parts of rubber and 50 parts of sulfur. Therefore, the mother compound contains 1/3 sulphur, which is equivalent to three times the amount of sulfur added.

The rubber used for the preparation of mother compound is NR, but the rubber becomes hard and hard to cut into small pieces in the winter.

According to experience, we used NR 50 copies and BR 50 parts to blend to solve this problem.

Now the market has already been sold with the sulfur mother compound, which is very convenient to use. Although the cost is slightly raised, it can be determined according to its cost performance.

In addition, there is also a kind of sulfur resin called polysulfide (made by Toyo chemical company), which is yellow brittle, fused to the rubber on the open mill, and is often used in rubber products such as rubber balls.

When the mixer is finished, the temperature is up to 140 degrees Celsius when the rubber is discharged into the tablet press. If the rubber is added to sulfur at high temperature, some of the sulfur will melt in the rubber and become liquid. If the sulfur is dispersed in the rubber in liquid, there is no problem. Once the rubber material is cooled down by the cooling effect, the molten sulfur will become lump.

In this way, the sulfur particles will not be further dispersed, and the small shape will exist in the rubber, even if the rubber is re modified, it will not change.

Therefore, it is better to add sulphur yellow when the rubber temperature drops below 70 degrees Celsius.

Sulphur yellow powder sold on the market has 200 orders and 300 mesh points.

300 the particle is fine, and people often think it is dispersive and likes to use it.

But whether it is true or not is to be proved by experiments.

In the experiment, 100 quality parts of NR were plasticized (as far as glue or SM RSL) was used to add 3 quality sulfur to the plastic compound.

Then the glue is put into the trial mill and the roller spacing is adjusted to the minimum.

Cut the film that is wrapped on the front roll, shrink the film, and get no good film.

For this reason, the rubber mixing machine can be stopped, and a piece of cellophane coated on the front roll will be pasted on a film of about 10 cm. Then the film will be cut off so that the film can be prevented from shrinking and made into a microscope test piece. If the microscope is used at about 400 times, the sulfur particles can be observed.

According to the cost performance of 300 mesh sulfur, it is self-evident. The author thinks that for the most purpose of rubber products, the use of 200 purpose sulfur can meet the requirements.

More than 30 years ago, the raw material for powdered sulphur used in rubber was sulphur collected from sulphur mines and collectively referred to as mineral sulphur. The sulphur used now is almost all recovered from petroleum refining, and the crystalline particles of mineral sulfur are large and soft and easy to crush.

As sulfur recovery powder is easy to caking, it is necessary to add a small amount of anti sticking agent.

In addition, there is a kind of sulfur coated with 3% operating oil for the tire factory.

As we all know, sulfur is not well dispersed in NBR. It is not noticeable when making black products. However, when producing light colored rubber products, it will appear dark brown spots, which are very ugly.

Maybe this is an old problem, but now we can buy the sulphur masterbatch from the market. If there is a requirement that we can not solve the negotiation, we can try the following methods.

The NBR is put into the mixer and added with sulfur mixing. The temperature of the roller rises, and the sulfur is dissolved in the rubber.

Then the material is cooled out and reused on the second day. The various additives are added according to the conventional method. Finally, the vulcanization accelerant is added to mix evenly. If this method is used, the spots can be eliminated.

2 sulfur spray

Sulfur in rubber migrates to its surface and forms crystals on the surface. This phenomenon is called frost spray.

This phenomenon occurs either in vulcanizates or vulcanizates.

When the unvulcanized rubber is sprayed, it will cause difficulties in bonding to the adhesive, resulting in poor adhesion. If the frost is serious, the sulphur ejected will be stuck in the concave part of the pverse part when manufacturing moulded products or moving mould injection products, so that it is easy to form a lack of glue.

This is due to the fact that sulphur can not be dissolved in rubber in a short time.

The first measure to prevent non vulcanized rubber frosting is to reduce the amount of sulfur. However, when the amount of sulfur is reduced, the elastic modulus of vulcanizates will decrease sharply and the hardness will also decrease.

Therefore, it is prudent to reduce the sulfur content.

The author believes that the sulfur content of semi finished products can be reduced to 2 critical points.

If we do not reduce the amount of sulphur, we can solve this problem by adding insoluble sulphur yellow.

If all sulfur can not be replaced with insoluble sulfur, half of the sulphur can be replaced with insoluble sulfur.

This can almost achieve the desired purpose.

The above method is applicable to the vulcanizate used in the factory for outward processing.

The external processing plant will not be strictly managed like the factory of the author. The raw materials stored in the warehouse are stored in the storeroom after several days, especially in cold storage. This will induce frost spray and produce insoluble sulfur.

After curing for a period of time, the vulcanized rubber products will also be frosted.

As a precaution, we should pay attention to the full vulcanization before planning to reduce the amount of sulphur.

The curing temperature and curing time are suitable. Do not hope to consider a little longer curing time.

But in any case, high temperature short curing is not appropriate.

After vulcanization, the rubber products should be avoided direct and sharp cooling. Attention should be paid to natural ventilation.

In this case, a cloth sleeve made of canvas and so on is covered on the container so as to prevent the occurrence of frost spray.

Insoluble sulfur does not work in the frosting phenomenon after vulcanization.

A slight difference from frost spray is that there will be visible sulfur crystals in the rubber mortar in winter. If you use a magnifying glass, you can clearly see that these are some trapezoid crystals.

Once there is such a crystallization, when the brush is coated with glue, the crystal will be attached to the end of the brush, and dents will form on the surface of the glue. When the glue is applied to the glue, it will crystallize at the blade edge of the scraping knife, like a longitudinal rubber mark.

The preventive measure is to add insoluble sulfur equivalent to half of the amount of sulfur required in the sulfur coordination. When using the glue, only the amount needed is obtained from the mortar tank, and the temporary unused mortar is stored in the gel tank, stirring slowly to prepare for use.

3 coke burning

The scorching of mixed rubber is most common in the rainy season.

Because of the Mooney viscometer and vulcanizer, both the new mixing compound and the reflux compound can be measured at any time, so that the scorching of the rubber can be prevented.

It is not necessary to carry out comprehensive determination in the production of mixed rubber factories in large quantities, and only one method of determination can be used only for the rubber compound.

The following methods are introduced to prevent coke burning.

First of all, to reduce the amount of vulcanization accelerator, but this will lead to a decline in physical properties of rubber products. It is very important to understand this. The use of vulcanization accelerators is rare, mostly using two or three accelerators.

Once the problem is solved, it will not prevent glue.