RU2700065C2 - Composite material for industrial rubber articles and method for production thereof - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention relates to rubber industry, in particular, to a composite material based on a rubber mixture reinforced with a cord, and a method for production thereof. Composite material for industrial rubber articles contains, wt. %: rubber mixture based on butadiene-methylstyrene rubber - 50–80 and ground rubber-coated polyamide cord with fibre length of up to 10 mm - 20–50. After crushing the cord on crushing equipment it is mixed with rubber, technical carbon, mineral fillers and plasticisers. Mixture is rolled into sheets, mixed with curing agent ingredients and rolled with forming of calender effect.

EFFECT: invention increases specific volumetric resistance to electric current and sliding friction coefficient of rubber article on steel.

8 cl, 15 tbl, 5 ex

Description

The invention relates to the rubber industry, in particular to composite materials based on rubber compounds reinforced with cord, and methods for their preparation.

Known rubber compound for the manufacture of rail and head rail gaskets-shock absorbers of rail fasteners (patent RU 2286363 C2, publ. 10.27.2006). The specified mixture is made by mixing butadiene-styrene rubber with a styrene content of 22-25 wt. including synthetic rubber of 1,4-polyisoprene, vulcanizing group consisting of sulfur, N-cyclohexyl-2-benzothiazolylsulfenamide, melt w, w'-hexachloroparaxylene in protective wax and N.N'-dithiodimorpholine, zinc oxide, synthetic fatty acids of the fraction C ₁₇ -C ₂₀ , N-phenyl-N'-isopropyl-p-phenylenediamine, petroleum bitumen, kaolin, carbon black, antioxidant and plasticizer. The mixture additionally contains divinyl rubber with a content of units CIS-1,4 from 85 to 95 mass. %, liquid paraffin and polymerized 2,2,4-trimethyl 1,2-dihydroquinoline.

However, the known rubber composition has a low specific volume resistivity due to the use of semi-active carbon black.

Closest to the claimed material is a composite material for gasket-shock absorbers for rail fastenings (patent RU 2347792 C1, publ. 02.27.2009), based on rubber compounds containing methyl styrene and divinyl rubbers, which can be used for the production of on-rail and rail-mounted gaskets-shock absorbers railway track. The composition contains the following components, mass. %:

- crushed rubberized polyamide cord with a fiber length of 10-15 mm -17.0-18.5;

- a rubber mixture based on methyl styrene and divinyl rubbers containing a vulcanizing group and inactive carbon black - 77-78;

- dispersed filler, namely crushed vypressovki from the stage of vulcanization of gaskets-shock absorbers - 2;

- crushed rubber crumb - 2.0-3.5.

The disadvantage of this invention is the presence in the composition of the material crushed extrusions obtained at the stage of vulcanization of gaskets-shock absorbers, and crushed rubber crumb. Crushed extruders from the vulcanization stage are an undervulcanized rubber mixture, while part of the extrusion can be “raw” and part vulcanized. The vulcanized parts of the extrusion, as well as crumb rubber usually do not have good adhesion to the bulk of the rubber compound, and can act as foreign inclusions, on the interface of which the destruction of the finished product can begin.

Closest to the claimed method is a method for producing a rubber mixture, (patent RU No. 2099362, available in the open registries of Rospatent, date of publication is not specified), in which the unsaturated rubber is mixed with a rubber mixer, carbon black, a sulfur-containing vulcanizing group, target additives and rubber waste, crushed by pre-treatment, while waste rubber used polyamide and viscose rubberized unvulcanized cords, which are subsequently crushed on rotary grinder type "shinorez" at a speed of 600 ^min-1 by a double pass through the gap of 6-8 mm between the movable and fixed blades, crushing further pulverized in a mill with two rolls with a gap 0,35-0,65 mm frictions 1: 3 08 by 3-4 pass through the gap, is processed on the second crushing rollers, in which one roll is smooth, the other is grooved, with a gap of 0.35-0.65 mm, friction 1: 3.08, by 3-4- multiple passes through the gap and a sheet thus prepared with a thickness of 3.5-6.5 mm are crushed on a drum noodle cutter and "with a rotation speed of 375 min ^-1 with a gap between the fitted onto the drum inclined movable blades and the stationary knife of 0.2-0.3 mm, wherein the grinding sheet produce transverse yarns oriented" calendering effect "in the processing in the crushing rollers, and then re-processing and grinding on crushing rollers and drum grinder type "noodle cutter" crushed mass when mixing the components to obtain a rubber mixture is introduced in an amount of 2-10 mass. hours per 100 wt. including rubber.

The disadvantages of this method are:

- the claimed "calendaring effect" in the blanks is not saved, because after grinding the sheet on a “noodle cutter” and mixing the ground processed waste in a rubber mixer with other ingredients of the rubber mixture, the orientation of the threads is chaotic;

- the occurrence of technological difficulties with the introduction of more than 10 masses, parts of crushed rubber cord, which is associated with heterogeneous distribution of threads of different lengths.

The main objective of the invention is the creation of a composite material for rubber products and a method for its production on the basis of elastomers reinforced with cord (fibrous filler), with a set of physico-mechanical properties that increase the operational characteristics of rubber products, such as rail rail fastenings.

The technical result consists in increasing the operational characteristics of rubber products, the coefficient of friction of sliding a rubber product on steel, and increasing the specific volume resistance to electric current.

The technical result is achieved by the fact that the composite material for rubber products containing a rubber mixture based on rubber and crushed synthetic cord contains these components, in the following quantity, mass. %:

- shredded synthetic cord with a fiber length of up to 10 mm - 20-50;

- a rubber mixture based on methyl styrene rubbers - 50-80.

It is preferable that the rubber composition contains methyl styrene rubber, technical inactive carbon, mineral fillers (chalk, zinc white, Santoguard, stearin), plasticizers, (petroleum bitumen, industrial oil), vulcanizing group ingredients.

It is optimal that the synthetic cord be rubberized.

Preferably, the vulcanizing group of the rubber composition contains N, N-dithiodimorpholine, sulfur and ethyl cimate.

The claimed technical result is also achieved by the fact that in the known method of manufacturing a composite material in which methyl styrene rubber is mixed with carbon black, mineral fillers, plasticizers, vulcanizing group ingredients, synthetic cord, crushed by preliminary processing, the synthetic cord is crushed on crushing equipment to fiber lengths less than 10 mm, after which they are mixed with methyl styrene rubber, carbon black and mineral GOVERNMENTAL fillers, plasticizers, the resulting mixture was rolled into sheets and fed again to the mixer for mixing with the ingredients of the vulcanizing system, wherein the resulting mixture is re-rolled.

Optimally, the ingredients of the rubber mixture and crushed synthetic cord at the first mixing stage are loaded into the rubber mixer at a temperature in the working chamber of not more than 80 ° C and mixed for 4-5 minutes, the resulting mixture is unloaded from the rubber mixer, fed to the cascade of at least two smooth rolls and roll into sheets no more than 15 mm thick, after which sheets of the rolled mixture should be cooled with water for at least 15 minutes.

In the second mixing stage, it is preferable to mix the rolled mixture of crushed synthetic cord and rubber mixture with the ingredients of the vulcanizing group, load into a rubber mixer at a temperature in the working chamber of not more than 70 ° C and mix them for 2 minutes, after which it is preferable to apply to the cascade from less than two smooth rollers, on which it is rolled into sheets, with a thickness of not more than 10 mm, and sheets of the rolled mixture should be cooled with water for at least 15 minutes.

The claimed technical result is an increase in operational characteristics due to two stages of mixing the ingredients in a rubber mixer, each of which is used for leafing the resulting mixture to orient the introduced fibers along the rolling direction of the rollers (acquiring the so-called “calender effect).

The introduction of crushed synthetic cordon of the first stage allows the use of inactive soot (carbon black), which, while maintaining strength indicators, reduces the conductivity of the material and increases the indicator "Specific volume resistance". Shredding the cord, including rubber (rubber cord, for example, waste from tire production), to a short fiber length of 5-10 mm, as well as introducing it into the rubber mixture at the stage of mixing the ingredients of the rubber mixture in a rubber mixer, allows you to get a uniform distribution of fibers throughout the volume of material , which is manifested in the stability of the physical and mechanical properties of the material. In the second stage, components of the vulcanizing group (dithiodimorpholine, sulfur, ethyl cimate) are added to the previously prepared semi-finished product. The two-stage process of manufacturing the material is due to the presence of cord fibers, which cause significant shear stresses in the mixture when it is mixed, which leads to a high mixing temperature. Therefore, the introduction of the ingredients of the vulcanizing group is isolated in the second stage. This allows you to get a good quality of mixing the ingredients, the best distribution of the cord fibers in the volume of the material and at the same time avoid vulcanization of the material in the rubber mixer chamber and the formation of "brewing". Good mixing and uniform distribution of cord fibers in the volume of the material helps to obtain stable results of physical and mechanical properties.

The uniformity of distribution has a positive effect on the manufacturability of further processing of the rubber compound, including in the manufacture of billets, and also allows to increase the filling of the rubber compound with obtaining higher physical and mechanical properties. An increase in the filling of the material with fibers of the chopped cord leads to its cost reduction, since the content of more expensive ingredients in the rubber compound is reduced. Uniform mixing and distribution of fibers throughout the volume of the material allows you to fill the mixture from 20 to 50 mass. % Moreover, as shown by experimental tests of rubber products with the claimed composition, the introduction of crushed synthetic cord in the indicated proportions increases the operational properties of products, for example, rail linings of rail fastenings of a railway track.

The introduction of crushed cord more than 50 mass. % causes technological difficulties in the manufacture and processing of the material. The high fiber content of the cord increases the temperature when mixing the components in the rubber mixer and increases the likelihood of vulcanization of the rubber compound. In addition, the high fiber content reduces the processability of leafing the material on the rollers. Also, the high content of crushed synthetic cord leads to excessive stiffness values of the finished product. The introduction of less than 20 mass. % degrades performance, such as coefficient of sliding friction on steel and abrasion.

The inventive method and composition are implemented as follows.

Initially, preliminary preparation of the cord is carried out before it is mixed with the rubber compound.

Cord, for example, a fibrous filler in the form of strong fabric synthetic fibers is crushed using crushing equipment to a fine fraction of less than 10 mm.

The cord is crushed, as a result of which it breaks up into individual fibers. Initially, the cord, including synthetic and rubberized, is fed to the Shinorez rotary grinder. This is where the initial grinding takes place. Next, the crushed cord is fed into a rotary crusher, in which grinding to a fraction of 5 to 10 mm occurs.

After that, the ingredients of the rubber compound: methyl styrene rubber; technical inactive carbon, mineral fillers, plasticizers mixed with crushed cord.

The manufacture of composite material is carried out in two stages. At the first stage, methyl styrene rubber, technical inactive carbon, mineral fillers (chalk, zinc white, Santogard, stearin), plasticizers (petroleum bitumen, industrial oil) are mixed with crushed cord, preferably synthetic.

The mixing process is carried out in a rubber mixer at a temperature in the working chamber of not more than 80 ° C, for 4-5 minutes, the resulting mixture is unloaded from the rubber mixer and fed to the cascade of at least two smooth rollers and rolled into sheets of a thickness of not more than 15 mm, after which sheets of the rolled mixture are cooled with water for at least 15 minutes.

In a second step, a milled mixture of crushed synthetic cord and rubber compound is mixed with the ingredients of a vulcanizing group, which may preferably include N, N-dithiodimorpholine, sulfur and ethyl cimate.

As mentioned above, the two-stage process of manufacturing the material is due to the presence of cord fibers, which cause significant shear stresses in the mixture when it is mixed, which leads to a high mixing temperature. Therefore, the introduction of the ingredients of the vulcanizing group is isolated in the second stage. This allows you to get a good quality of mixing the ingredients, a better distribution of the cord fibers in the volume of the material, while avoiding the vulcanization of the material in the chamber of the rubber mixer and the formation of "brewing", which helps to obtain stable results of physical and mechanical properties.

In the second stage of the process, the rolled mixture of the first stage and the components of the vulcanizing group are loaded into the rubber mixer at a temperature in the working chamber of not more than 70 ° C and mixed for 2 minutes, after which the mixture is fed to a cascade of at least two smooth rollers, on which it is rolled into sheets with a thickness of not more than 10 mm, after which the sheets of the rolled mixture are cooled with water for at least 15 minutes.

From the obtained composite material, at the second stage, the production of rolled sheets is carried out, before the calendaring effect is acquired from them. The release takes place on rollers (the material is passed through a gap of 9-15 mm between the cylindrical rolls and a sheet is formed), therefore, the properties of the material acquire a “calender effect”: in the direction of rolling along the rollers, the cord fibers are mainly oriented inside the sheet of material.

The properties of both a sheet of composite material and parts made of such material acquire anisotropy. This allows you to obtain the necessary physical and mechanical properties during the work of finished parts under conditions of application of the load in a certain direction.

From the obtained composite material in the form of blanks of a certain geometric shape, it is possible to produce parts by direct compression molding using technological equipment (molds) installed on vulcanizing presses.

A specific implementation of the method of manufacturing a reinforced composite material can be illustrated by the following examples:

Example 1

A composite material reinforced with fiber filler (cord) “PD-RE-Cord” with a content of 20 masses was made. % crushed rubberized polyamide cord and 80 mass. % rubber compound.

Initially, synthetic cord was prepared. Cord, consisting of a fabric of polyamide yarns and a rubberizing rubber layer, in an amount of 20 mass. % was first crushed on a Shinorez rotary grinder with a drum rotation speed of 600 rpm and a gap between movable and fixed knives of 1.5 mm. Then, the crushed mass was fed into a rotary crusher with a drum rotation speed of 600 rpm and a gap between the movable and fixed knives of 1 mm, in which the fibers were further chopped to sizes of 5 mm.

Next, the manufacturing of the composite material directly was carried out by mixing the crushed polyamide cord with other ingredients. Mixing was carried out in two stages.

In the first stage, crushed cord and the following rubber compound ingredients were mixed:

The specified ingredients of the composite material were loaded into a rubber mixer PC 270-30 at a temperature in the working chamber of not more than 80 ° C and they were mixed for 4-5 minutes, with the temperature of the mixture controlled before unloading so that it was no more than 125 ° C. After unloading from the rubber mixer, the semi-finished product (mixture) of the first stage was fed to the cascade of at least two smooth rollers CM 2100 660/660, on which it was rolled into sheets no more than 15 mm thick. Then, the rolled mixture was fed into a cooling device, where water was cooled for at least 15 minutes. The prepared semi-finished product (mixture) of the first stage was then again loaded into the rubber mixer PC 270-30 and mixed with the ingredients of the vulcanizing group:

These ingredients were loaded into a rubber mixer PC 270-30 at a temperature in the working chamber of not more than 70 ° C and they were mixed for at least 2 minutes, with the temperature of the mixture being monitored before unloading so that it was no more than 110 ° C. After unloading from the rubber mixer, the finished mixture was also fed to the cascade of at least two smooth rollers SM 2100 660/660, on which it was rolled into sheets with a thickness of not more than 10 mm, after which the rolled mixture was fed into a cooling device, where they were cooled with water during not less than 15 minutes.

After mixing, the resulting mixture was rolled into sheets with a thickness of 12 mm for the subsequent manufacture of products. To do this, the leaf mixture was first heated to a temperature of 60 ° C on crushing rollers DR P 800 550/550 or DR P 800 490/610, passing through the gap 5 times, increasing its ductility. Then, the heated material was rolled on smooth rollers SM PD 2100 660/660 or SM PD 1500 660/660 to obtain a sheet with a thickness of 12 mm. The resulting composite material in the form of sheets was used for further manufacturing of products. In this case, the sheet material acquired a calendering effect due to the passage between the rolls of the rollers and stretching in one direction.

As a result, the following physicomechanical parameters of the obtained composite material were established, shown in table 3:

The tests carried out showed an increase in the coefficient of sliding friction on steel and an increase in the specific volume resistance of the obtained material compared to the parameters indicated in the description of the prototype patent.

Example 2

A composite material was made reinforced with a fibrous filler (cord) with a content of 35 mass. % crushed rubberized polyamide cord and 65 mass. % rubber compound.

Initially, a synthetic cord was prepared, as in Example 1, but the fibers were milled to a size of 7 mm.

Next, the manufacturing of the composite material directly was carried out by mixing the crushed polyamide cord with other ingredients, analogously to example 1. The mixing was carried out in two stages.

In the first stage, the following ingredients were mixed:

In the second stage, the following ingredients were mixed:

After mixing, the resulting mixture was rolled in accordance with example 1. The resulting composite material in the form of sheets was used for further manufacturing of products.

As a result of tests of a composite material with the composition of the ingredients of example 2, its following physical and mechanical properties were established:

In the composition according to example 2, an increase in the coefficient of sliding friction on steel, an increase in the specific volume resistance in comparison with the prototype, were found. In addition, compared with example 1, in which the composition with a 20% cord content is indicated, the composition of this example also shows a decrease in the abrasion index from the upper permissible limit.

Example 3

A composite material reinforced with a fibrous filler (cord) with a content of 50 wt. % crushed rubberized polyamide cord and 50% rubber compound.

Initially, a synthetic cord was prepared analogously to Example 1, but the fibers were milled to sizes of 8 mm.

Next, the manufacturing of the composite material directly was carried out by mixing the crushed polyamide cord with other ingredients, analogously to example 1. The mixing was carried out in two stages.

In the first stage, the following ingredients were mixed:

In the second stage, the following ingredients were mixed:

After mixing, the resulting mixture was rolled, analogously to example 1. The resulting composite material in the form of sheets was used for further manufacturing of products. In this case, the rolled material acquired a calendering effect due to the passage between the rolls of the rollers and stretching in one direction.

As a result, the following physicomechanical indices of the obtained composite material were established:

In the resulting composition according to example 3, there was an increase in the coefficient of sliding friction on steel, an increase in the specific volume resistance in comparison with the prototype. In addition, tests showed that the value of the index of abrasion by composition in Example 3 is much lower than the upper permissible limit established by the Guest.

Example 4

A composite material was made reinforced with a fibrous filler (cord) with a content of 22% by weight. crushed rubberized polyamide cord and 78% of the mass of the rubber compound.

Initially, a synthetic cord was prepared, analogously to Example 1, with fiber grinding to a size of 9 mm.

Next, the manufacturing of the composite material directly was carried out by mixing the crushed polyamide cord with other ingredients, analogously to example 1. The mixing was carried out in two stages.

In the first stage, the following ingredients were mixed:

In the second stage, the following ingredients were mixed:

After mixing, the resulting mixture was rolled, as in example 1. The resulting composite material in the form of sheets was used for further manufacturing of products. In this case, the rolled material acquired a calendering effect due to the passage between the rolls of the rollers and stretching in one direction, and had the following physical and mechanical parameters shown in Table 12:

In the obtained composition according to example 4, an increase in the coefficient of sliding friction on steel, an increase in the specific volume resistance in comparison with the prototype, were recorded. In addition, tests have shown that the value of the abrasion index is lower than the upper permissible limit established by the Guest.

Example 5

A composite material reinforced with a fibrous filler (cord) with a content of 30 wt. % crushed rubberized polyamide cord and 70% rubber compound.

Initially, a synthetic cord was prepared, as in Example 1, but the fibers were crushed to a size of 9.5 mm.

Next, the manufacturing of the composite material directly was carried out by mixing the crushed polyamide cord with other ingredients, analogously to example 1. The mixing was carried out in two stages.

In the first stage, the following ingredients were mixed:

In the second stage, the following ingredients were mixed:

After mixing, the resulting mixture was rolled, analogously to example 1. The resulting composite material in the form of sheets was used for further manufacturing of products. In this case, the sheet material acquired a calendering effect due to the passage between the rolls of the rollers and stretching in one direction.

As a result, the following physical and mechanical properties of the material with the composition shown in Example 5 were determined:

In the resulting composition according to example 5, an increase in the coefficient of sliding friction on steel, an increase in the specific volume resistance in comparison with the prototype, were recorded. In addition, tests have shown that the material from the claimed composition has a value of the abrasion index below the established by the Guest of the upper acceptable limit.

The inventive composite material for rubber products obtained by the claimed method can be widely used as cord-reinforced materials used for rubber products with high performance, friction coefficient of sliding of a rubber product on steel, and increased specific volume resistance to electric current.

Claims (10)

1. Composite material for rubber products, including rubber based on rubber and crushed cord, characterized in that it contains the following components, wt.%:  crushed rubberized polyamide cord with a fiber length of up to 10 mm - 20-50;  rubber mixture based on butadiene-methylstyrene rubber - 50-80. 2. The composite material according to claim 1, characterized in that the rubber mixture contains butadiene-methylstyrene rubber, technical inactive carbon, mineral fillers, plasticizers, a vulcanizing group including N, N-dithiodimorpholine, sulfur and ethyl cimate. 3. A method of manufacturing a composite material for rubber products according to claim 1, wherein the rubber mixture containing rubber, carbon black, mineral fillers, plasticizers and vulcanizing group ingredients is mixed with a pre-ground cord, characterized in that the rubberized polyamide cord is ground into crushing equipment up to a fiber length of not more than 10 mm, after which the cord is mixed with butadiene-methylstyrene rubber, carbon black, mineral fillers and plastic proof operation, the resulting mixture was rolled into sheets, carried reblending listovannogo material with the ingredients of the vulcanizing system and produce milling the resulting mixture to form the calendering effect. 4. The method according to p. 3, characterized in that use rubberized synthetic cord, for example waste from tire production. 5. The method according to p. 3, characterized in that the rubber mixture contains butadiene-methylstyrene rubber, technical inactive carbon, mineral fillers, plasticizers, vulcanizing group ingredients. 6. The method according to p. 3, characterized in that the rubber is butadiene-methyl styrene, carbon is technical inactive, mineral fillers, plasticizers and crushed rubberized polyamide cord are loaded into a rubber mixer at a temperature in the working chamber of not more than 80 ° C and mix them for 4 -5 minutes, the resulting mixture is unloaded from the rubber mixer and fed to the cascade of at least two smooth rollers and rolled into sheets with a thickness of not more than 15 mm, after which the sheets of the rolled mixture are cooled with water for at least 15 minutes. 7. The method according to p. 3, characterized in that the composition of the elements of the vulcanizing group includes N, N-dithiodimorpholine, sulfur and ethyl cimate. 8. The method according to p. 3, characterized in that the rolled mixture of crushed rubberized polyamide cord and rubber mixture is mixed with vulcanizing group ingredients, loaded into a rubber mixer at a temperature in the working chamber of not more than 70 ° C and mixed for 2 minutes, after whereupon the mixture is fed to the cascade of at least two smooth rollers, on which it is rolled into sheets with a thickness of not more than 10 mm, after which the sheets of the rolled mixture are cooled with water for at least 15 minutes.