JPH0618925B2 - Method for producing rubber product using vulcanized rubber pulverized product - Google Patents

Description

TECHNICAL FIELD The present invention relates to an improvement in a method for producing a rubber product using a pulverized product of vulcanized rubber.

(Prior Art) With the recent increase in demand for rubber products for automobiles and the like, the treatment of industrial waste such as old tires has become a serious problem. Therefore, in order to solve this problem, crushed rubber products are used as the main raw material for railroad track mats (so-called ballast mats, slab mats, etc.), walkway mats, etc. Rubber mats are manufactured. The following methods have been conventionally known as methods for producing rubber products such as this rubber mat.

A method in which a vulcanizing agent is added to crushed vulcanized rubber and heat compression molding is performed. (Hereinafter, referred to as Prior Art I) A method in which a vulcanized rubber swelling product is swollen, and then a vulcanizing agent is added, followed by heat compression molding. (Hereinafter, referred to as Conventional Technology II) A method of adding a binder (rubber-based, urethane resin, epoxy resin, ethylene copolymer, polyfunctional monomer, latex, etc.) to a crushed vulcanized rubber (hereinafter, referred to as Conventional Technology) (III)) A method in which a vulcanized rubber pulverized product is discharged, and then a vulcanizing agent is added, followed by heat compression molding. (See, for example, JP-A-49-60380 and JP-A-50-134085, hereinafter referred to as Prior Art IV.
Japanese Patent Laid-Open No. 56-43339 discloses that "100 parts by weight of waste vulcanized rubber and 10 parts by weight or more of new rubber are subjected to desulfurization regeneration treatment. An invention relating to a "rubber compounding composition blended in parts by weight" is disclosed. (Hereinafter, referred to as Prior Art V) (Problems to be Solved by the Invention) As in Prior Art I, a product obtained by adding a crosslinking agent such as sulfur to a vulcanized rubber pulverized product and performing heat compression molding has a bonding force between particles. It is weak and cannot be used as a material requiring high strength. Further, the addition of a softening agent, a filler or the like further weakens the binding force, so that there is a problem that the adjustment range of the elastic modulus, which is important when used as a vibration damping material, is extremely narrow.

The conventional techniques II to V improve the conventional technique I. However, the products manufactured by the conventional techniques II to IV do not have a sufficient effect of improving the physical properties, and the conventional technology V has excellent physical properties. High cost.

The present invention has been made in view of such problems of the prior art, and an object thereof is to produce a rubber product which is inexpensive and has excellent physical properties equivalent to a kneaded rubber containing a recycled rubber. To provide a method for producing a rubber product using a vulcanized rubber pulverized product.

(Means for Solving the Problems) In order to achieve the above object, the gist of the present invention is to 100 parts by weight of vulcanized rubber pulverized product, 1 to 10 parts by weight of regenerated oil and 100 parts by weight of raw rubber. Non-vulcanizable rubber compound (also referred to as coating rubber) containing 10 to 400 parts by weight of vulcanized rubber and a rubber compounding agent containing no vulcanizing agent
A vulcanized rubber pulverized product is used, which is characterized by adding parts by weight, stirring and heating to 170 ° C. or higher, then cooling, then adding and mixing a vulcanizing agent and necessary compounding agents, and then heat compression molding. There is a method of manufacturing a rubber product.

The vulcanized rubber pulverized product preferably has a natural rubber ratio of 10% or more.

As the raw material rubber, vulcanizable rubber such as natural rubber, isoprene rubber and styrene-butadiene rubber is preferable.

As a necessary compounding agent to be added together with the vulcanizing agent, a softening agent,
Examples thereof include modulus modifiers such as organic and inorganic fillers, vulcanization accelerators, accelerator assistants and activators.

(Function) Adding regenerated oil and non-vulcanizable rubber compound (coating rubber) to crushed vulcanized rubber, stirring and heating to 170 ° C or higher to perform surface desulfurization and rubber coating in the same process The surface of the crushed rubber particles and the coating rubber penetrate into each other to be integrated, and then the vulcanizing agent and the necessary compounding ingredients are added and mixed, and then heat compression molding is performed to completely bond the rubber particles. It is possible to obtain a rubber product exhibiting high physical properties.

The surface-desulfurized and coated rubber particles have a structure in which crushed rubber particles are filled in kneaded rubber (coating rubber) in terms of morphology, so even if a softening agent or a filler is added, the bonding between rubber particles The force is not weakened and the elastic modulus adjustment range becomes extremely wide.

Further, in order to perform satisfactory coating in the desulfurization / rubber coating step by stirring, it is desirable to use the coating rubber to which pulverized rubber is added. Raw rubber 10 as a coating rubber as in the present invention
If 0 parts by weight or more of vulcanized rubber pulverized product is added to 10 parts by weight, it is easily pulverized at the time of stirring, and as a result, the surface area increases and coating is completed in a short time. When the amount of the vulcanized rubber pulverized product added exceeds 400 parts by weight, the kneading of the coating rubber itself becomes difficult.

The added amount of coating rubber is 10
If it is less than 2 parts by weight with respect to 0 parts by weight, the physical properties are not sufficiently improved, and if it exceeds 50 parts by weight, interparticle blocking occurs,
It becomes difficult to handle and economical.

Addition amount of recycled oil to 100 parts by weight of pulverized vulcanized rubber is 1
If it is less than 10 parts by weight, the surface desulfurization is not sufficient, and if it exceeds 10 parts by weight, the inside of the rubber particles is modified and the physical properties originally possessed by the vulcanized rubber pulverized product deteriorate.

(Example) An example of the present invention will be described below in the order of steps.

[Production of non-vulcanizable rubber compound (coating rubber)]

After kneading the mixture shown in Table 1 on the next page with a Banbury mixer, it is formed into a sheet with a thickness of about 8 mm, and after cooling it is about 10 cm.
It was cut into a corner and used as a coating rubber. In Table 1, the numbers indicate parts by weight. As the vulcanized rubber crushed product, crushed product of large tire tread rubber (average particle size 16
Mesh) was used.

[Desulfurization and rubber coating] Then, to 100 parts by weight of the vulcanized rubber pulverized product, regenerated oil and coating rubber A or B were added in an amount (parts by weight) shown in Table 2 on the next page, and the mixture was mixed with a super mixer. 200 ° C
Then, the mixture was cooled to about 50, and the desulfurization and coating of the surface of the vulcanized rubber pulverized product were completed.

[Addition and Mixing of Vulcanizing Agent and Other Compounding Agent] Desulfurized and coated ground rubber was added to the following Table 3
A compound containing a vulcanizing agent and other compounding agents as described in 1), 2) or 3) was added and mixed for about 3 minutes until the temperature reached 90 ° C. The numbers in Table 3 indicate parts by weight.

[Heat compression molding and measurement of physical properties] Heat compression molding of the mixture obtained as described above,
A 20 mm thick slab was obtained. And this slab is about 2.0
A test piece (according to JIS K6301) having a predetermined shape was cut out from a sliced piece having a thickness of up to 2.2 mm and used for measurement of physical properties. The results are shown in Tables 4 and 5 below. Table 4, Table 5
The formulations of Examples 1 to 3 and Comparative Examples 1 to 4 in Table 2 are shown in Table 2.
Is the same as. Table 4 shows the results of using the vulcanizing agent and the other compounding agents having the composition shown in Table 3B.

From Table 4 above, the following points are clear.

In Examples 1 to 3, since an appropriate amount of regenerated oil and an appropriate amount of coating rubber containing the pulverized rubber were added to the vulcanized rubber pulverized product, the bond between the rubber particles in the desulfurized coating layer was strong. Shows extremely high tensile strength and tear strength as compared with Comparative Examples 1, 3 and 4.

Since the coating rubber was not added to Comparative Example 1, the tensile strength, elongation, and tear strength are all extremely low values.

Since an excessive amount of coating rubber was added to Comparative Example 2, blocking occurred between the rubber particles.

In Comparative Example 3, since the amount of regenerated oil added was large, the tensile strength and tear strength were low.

Since the pulverized product of vulcanized rubber was not added to the coating rubber of Comparative Example 4, the pulverization during stirring was difficult and the coating rubber remained as a lump. Therefore, the bond between rubber particles is also weak, and the tensile strength, elongation, and tear strength are all at low levels.

From Table 5, the following points are clear.

In the examples, the hardness can be lowered by adding the aroma oil (blending B) and the hardness can be increased by adding the silica (blending C) within the range where other mechanical properties are not practically problematic. . As described above, the present invention enables a large adjustment of product hardness.

In the comparative example, the addition of the aromatic oil (blending) not only lowers the hardness but also significantly lowers other mechanical properties and cannot be put to practical use. Further, when silica (blended c) was added, it became a brittle vulcanized product, and it was not possible to even measure the mechanical properties.

(Effects of the Invention) (1) According to the present invention, a rubber product which has excellent mechanical properties as compared with a conventional rubber product made of vulcanized rubber pulverized products and which is extremely useful in practice and whose hardness can be freely adjusted. It can be manufactured at low cost.

(2) Since it is possible to manufacture rubber products having a wide variety of hardnesses, packing, bushing, etc., which can be manufactured only by kneading rubber in the past, can be manufactured inexpensively by the method according to the present invention.

(3) Since it is a method for manufacturing a rubber product using a crushed vulcanized rubber product, it is possible to effectively use waste tires, waste belts, and the like, and the invention has an extremely great industrial utility value.

Claims (1)

[Claims] 1. A vulcanized rubber crushed material is contained in an amount of 1 to 10 parts by weight per 100 parts by weight of a vulcanized rubber pulverized product, and 10 to 400 parts by weight of a vulcanized rubber pulverized product per 100 parts by weight of a raw material rubber, and no vulcanizing agent. After adding 2 to 50 parts by weight of a non-vulcanizable rubber compound containing a rubber compounding agent, stirring and heating to 170 ° C. or higher and then cooling, and then adding and mixing a vulcanizing agent and necessary compounding agents, Method for producing rubber product using crushed vulcanized rubber characterized by heat compression molding