JP2006348179A - Rubber composition and pneumatic tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rubber composition and pneumatic tires, capable of increasing material recycle ratio of waste rubber obtained from rubber products such as used tires, by keeping superior rubber properties especially higher fracture characteristics than conventional reclaimed rubber and powdered rubber. <P>SOLUTION: The rubber composition contains a powdered rubber obtained by pulverizing treatment of rubber tips, wherein the powdered rubber is a rubber composition produced by a pulverized rubber treatment method comprising a pulverizing step (A) in which the rubber raw material treated to be chip-like is gradually finished to be fine-pulverized rubber from rough-powdered rubber through medium-powdered rubber by rough pulverization, medium pulverization and fine pulverization and by using a pulverizing means with a clinging preventive being added, and a classifying/reclaiming step (B) in which the pulverized rubber is classified and at least a part thereof is recovered as fine powdered rubber products. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a rubber composition and a pneumatic tire (hereinafter sometimes simply referred to as “tire”). More specifically, the present invention relates to a powder rubber-containing rubber composition capable of maintaining high fracture characteristics and improving the recycling rate of waste rubber obtained from rubber products such as used tires, and a pneumatic tire using the same.

Waste tires have a higher recovery rate than ordinary plastic products, and are reused as fuel, especially in cement factories. However, in recent years, with the increase of environmental problems, there is a demand for improvement of so-called material recycling rate using tire rubber pieces or rubber powder as they are. In particular, a typical method for obtaining rubber powder is roll crushing, but the conventional method has a large heat history during crushing, and it is basically difficult to reduce the particle size. There has been a problem that the rubber properties (particularly, the fracture properties) are inevitably deteriorated simply by adding the obtained rubber powder to the new rubber.
On the other hand, heat desulfurization treatment of rubber powder by an oil pan method is known as a technique for preventing deterioration of workability (see, for example, Patent Document 1). In this method, rubber powder after roll grinding is used. On the other hand, since it is a usual method to perform the treatment as it is, a decrease in physical properties is unavoidable.
As described above, in a rubber composition using waste rubber obtained from used rubber products, sufficient rubber characteristics, in particular, destructive characteristics, are secured under the recent demand for improving the material recycling rate of used rubber products. Therefore, a technique for obtaining a useful rubber composition as compared with the conventional art has been demanded.

JP 2004-35663 A

  Under such circumstances, the present invention is a material for waste rubber obtained from rubber products such as used tires by maintaining excellent rubber properties, particularly high fracture characteristics, compared to conventional recycled rubber and powder rubber. An object of the present invention is to provide a rubber composition and a pneumatic tire capable of improving the recycling rate.

As a result of intensive studies to develop a rubber composition and a tire having the above-mentioned preferable properties, the present inventors have newly developed a specific pulverization step and a specific classification step performed while adding an anti-sticking agent. It has been found that by obtaining powder rubber from a rubber chip of waste rubber using a simple manufacturing method, excellent rubber physical properties, particularly high fracture characteristics can be obtained in a rubber composition using the rubber powder.
The present invention has been completed based on such findings.
That is, the present invention
(1) A rubber composition containing powdered rubber obtained by pulverizing rubber chips, wherein the powdered rubber is roughened while adding an anti-sticking agent to the raw rubber material processed into chips. A fine pulverization step (A) for sequentially finishing from coarsely crushed rubber to intermediate pulverized rubber to finely pulverized rubber by pulverization, intermediate pulverization, and finish pulverization; A rubber composition produced by a finely pulverized rubber processing method having a classification recovery step (B) to be recovered as
(2) In the fine pulverization step (A), using a roll pulverization means comprising a pair of coarse pulverization rolls, a medium pulverization roll and a finish pulverization roll as fine pulverization means, between a pair of pulverization rolls in each stage, The rubber composition of (1) above, which is roughly crushed, medium crushed and finish crushed, respectively
(3) The rubber composition according to the above (2), wherein the outer peripheral surfaces of the pair of rough pulverizing rolls, medium pulverizing rolls, and finish pulverizing rolls are formed as irregular surfaces.
(4) A pair of rough pulverizing rolls, medium pulverizing rolls, and finishing pulverizing rolls are arranged, and the pulverizing rolls have groove shapes with outer peripheral surfaces of # 5 to # 20, # 10 to # 30, and # 15 to # 40, respectively. The rubber composition according to the above (3) formed on the uneven surface by
(5) The rubber composition according to the above (3) or (4), wherein the surface speed difference ratios of the opposing pulverizing rolls of the pair of rough pulverizing roll, medium pulverizing roll and finish pulverizing roll are each 1/40 to 1/5. object,
(6) In the fine pulverization step (A), using a fixed blade and a pulverization roll as fine pulverization means, rough pulverization, intermediate pulverization and finish pulverization are performed between the fixed blade and the pulverization roll in each stage (1 ) Rubber composition,
(7) A preliminary pulverization step (Y) is provided upstream of the fine pulverization step (A), and the rubber raw material is subjected to a fine pulverization treatment by a preliminary pulverization means in the preliminary pulverization step (Y), and then the fine pulverization step (A The rubber composition of the above (1) to (6),
(8) A separation step (Z) is provided subsequent to the fine pulverization step (A), and an impact force is applied to the rubber particles contained in the fine pulverization rubber and connected to each other in the separation step (Z). The rubber composition of the above (1) to (7), which is applied and forcibly separated;
(9) The rubber composition according to (1) to (8), wherein the rubber raw material is a rubber chip having a size of 1 mm to 8 mm,
(10) The rubber composition according to any one of (1) to (9), wherein the powder rubber contains 75% by mass or more of a powder that has passed through a 100 mesh filter.
(11) The rubber composition of the above (10) containing 75% by mass or more of the powder rubber that has passed through a 200-mesh filter, and (12) the rubber composition of (1) to (11) above. A pneumatic tire, characterized by
Is to provide.

  According to the present invention, a finely pulverized rubber having a very small particle diameter can be obtained easily and efficiently by the pulverization step (A) in which the chip-shaped rubber raw material is pulverized rubber while adding an anti-sticking agent. By passing through a subsequent separation step (Z) provided as desired, the finely divided rubber particles dispersed by applying an impact force to the continuous finely pulverized rubber particles and classified efficiently by the classification recovery step (B). Powdered rubber is obtained. The rubber composition of the present invention containing a powder rubber having a very small particle size obtained in the classifying and collecting step (B) by this production method is excellent in rubber physical properties, maintains particularly high fracture characteristics, and uses the composition for tires. Thus, the material recycling rate of waste rubber obtained from rubber products such as used tires can be improved.

The rubber composition of the present invention is a rubber composition containing a powder rubber obtained by finely pulverizing rubber chips, and the powder rubber is a sticking preventive agent by means of finely pulverizing a rubber raw material processed into chips. A finely pulverizing step (A) in which coarsely pulverized rubber, intermediate pulverized rubber, and finish pulverized powder are gradually finished from coarsely pulverized rubber to intermediately pulverized rubber to finely pulverized rubber, and at least a part of the finely pulverized rubber is classified. It is necessary to be a powder rubber produced by a finely pulverized rubber processing method having a classification recovery step (B) for recovering as a fine powder rubber product.
The method for producing powder rubber used in the rubber composition of the present invention comprises the following three steps shown in FIGS.
Pre-grinding step (Y): Rubber chips are processed into finely crushed rubber by a pre-pulverizer 1 which is a pre-grinding means.
Finely pulverizing step (A): The finely pulverized rubber is pulverized stepwise by adding the anti-sticking agent by the pulverizer 2 as a finely pulverizing means, and finally finished into finely pulverized rubber.
Classification recovery step (B): The finely pulverized rubber is classified into powder rubber having a predetermined particle size (including fine powder rubber having a particle size smaller than the predetermined particle size) by the classifier 3 which is a classifying means, and the others. Classify (sort) the product and collect it as a product.
In addition, as will be described later, the preliminary pulverization step is an optional step that is incorporated into the above-described manufacturing method as necessary.

In the preliminary pulverization step (Y), as shown in FIG. 2, for example, a rubber chip obtained by crushing a cut tire obtained by cutting waste tires (removed tire reinforcing material such as peat wires, steel belts and plies) into a predetermined size. (Tire chip) is charged into the pre-pulverizer 1 as a rubber raw material, and processed into finely pulverized rubber by a pulverization section provided in the pulverization chamber. The rubber chips supplied to the pre-pulverizer 1 are appropriate, but cutting to a size of about 1 mm to 8 mm helps to reduce the particle size of the finely pulverized rubber. By pre-ripening the rubber chips, the fine pulverization by the preliminary pulverizer 1 is made smooth, but there is no problem in processing at normal temperature, and whether or not the preheating additional work is appropriately performed. Selected.
Further, by repeatedly pulverizing the rubber chip with the preliminary pulverizer 1 a plurality of times, a finely pulverized rubber having a small particle size can be produced.
The range of the size of the rubber chip is not limited to 1 mm to 8 mm, but by setting the size of the rubber chip within the above range, the preliminary grinding step ( The reduction in the grinding efficiency in Y) is suppressed.
As the preliminary pulverizer 1, an appropriate one such as an extruder for stirring and pulverizing rubber chips or a roll pulverizer for pulverizing with a roll is selected.

In the fine pulverization step (A), as shown in FIGS. 1 and 2, the finely pulverized rubber processed by the preliminary pulverizer 1 is finely pulverized by the fine pulverizer 2 through rough pulverization to intermediate pulverization. Processed into rubber. The fine pulverizer 2 is roll pulverizing means in which the rough pulverization unit 2a, the medium pulverization unit 2b, and the finish pulverization unit 2c are continuously arranged from the upper stage (or upstream) to the lower stage (or downstream). The rough pulverizing unit 2a, the intermediate pulverizing unit 2b, and the finishing pulverizing unit 2c are all arranged in one or a plurality of pairs of rough pulverizing rolls 2a11, 2a12, a pair of medium pulverizing rolls 2b11, 2b12, and a pair of finishing pulverizing rolls 2c11, 2c12. This is the configuration.
The rubber chips are roughly pulverized by the rough pulverizing rolls 2a11 and 2a12, and only the pulverized rubber having a predetermined particle size planned in advance by the sieving machine 2a2 is sent to the intermediate pulverizing process as the rough pulverized rubber, and those exceeding the predetermined value are not The rough crushed rubber is returned to the rough pulverized portion 2a and processed again. The coarsely pulverized rubber is supplied to the medium pulverizing rolls 2b11 and 2b12 and is pulverized, and only the pulverized rubber having a predetermined particle diameter is sent to the finishing process as the intermediate pulverized rubber by the sieving machine 2b2. It returns to the middle grinding part 2b as a middle ground rubber and is processed again. Further, the medium pulverized rubber is finished into finely pulverized rubber by finishing pulverizing rolls 2c11 and 2c12. The finely pulverized rubber processed in the finish pulverization step is sent to the classifier 3 in the classification recovery step (B).
The metals contained in the non-rough pulverized rubber and the non-medium pulverized rubber discharged in each process of rough pulverization and medium pulverization by the fine pulverizer 2 are immediately returned to the rough pulverization part 2a and the medium pulverization part 2b, respectively. It is removed by the metal removing devices 2a3 and 2b3.

The anti-sticking agent added in the fine pulverization step is supplied to the agitators 2a4, 2b4, and 2c4 arranged above the rough pulverization part 2a, the medium pulverization part 2b, and the finish pulverization part 2c, and the crushed rubber in the agitator Are uniformly stirred and put into the rough pulverizing part, the medium pulverizing part and the finishing pulverizing part, respectively.
As the anti-sticking agent, fillers (calcium carbonate, alumina, zinc oxide, etc.) and reinforcing materials (carbon black, talc, silica, etc.) are suitable. The type of the anti-sticking agent is appropriately selected in consideration of the manufacturing cost, the use of finely pulverized rubber, and the like.
By adding the anti-sticking agent, the surface of the pulverized rubber is coated, and the crushed rubber is prevented from adhering and bonding again, and the sorting by the sieving machines 2a2 and 2b2 and the classification (sorting) by the classifier 3 are efficient and There is an advantage that becomes easy. While securing this type of advantage, a small amount of anti-sticking agent contributes to cost reduction and is convenient for reuse as a tire raw material.

The outer peripheral surfaces of the pulverizing rolls 2a11, 2a12, 2b11, 2b12, 2c11, and 2c12 in the pulverizer 2 are usually uneven surfaces. This uneven surface is composed of one or both cross-shaped grooves formed by grooves by knurls, one formed by cutting grooves in a spiral shape on the outer peripheral surface, and diamond powder on the outer peripheral surface. Includes those formed by thermal spraying. The crushed rubber (rough crushed rubber, medium crushed rubber, fine crushed rubber) is crushed by the outer peripheral surfaces of the rough crushed rolls 2a11, 2a12, medium crushed rolls 2b11, 2b12, and finish crushed rolls 2c11, 2c12 being uneven. Between the rough pulverizing roll, the middle pulverizing roll, and the finishing pulverizing roll in the stage, pulverization is performed by shearing force.
The pair of coarse pulverizing rolls 2a11, 2a12, the pair of medium pulverizing rolls 2b11, 2b12 and the pair of finishing pulverizing rolls 2c11, 2c12 have one of the paired pulverizing rolls at the low speed side and the other at the high speed side, There is a speed difference in rotation.
Process conditions such as groove shape, surface speed difference ratio and roll gap (gap) of grinding rolls 2a11, 2a12, 2b11, 2b12, 2c11, 2c12 in each stage are adjusted according to the planned particle diameter of the grinding rubber. And pulverize.
When the groove shapes of the rough pulverizing rolls 2a11, 2a12, the medium pulverizing rolls 2b11, 2b12 and the finishing pulverizing rolls 2c11, 2c12 are set to # 5 to # 20, # 10 to # 30, and # 15 to # 40, respectively. By setting each range, it is possible to suppress a decrease in pulverization efficiency. In the case where the speed difference ratios of the rough pulverizing rolls 2a11, 2a12, the medium pulverizing rolls 2b11, 2b12 and the finishing pulverizing rolls 2c11, 2c12 are set to 1/40 (1:40) to 1/5 (1: 5), In any case, excellent production efficiency can be ensured.
The configuration of the pulverizing rolls 2a11, 2a12, 2b11, 2b12, 2c11, 2c12 (the number of steps, groove shape, surface speed difference ratio, roll gap, etc.) at each stage is selected according to the pulverized particle size.
In order to suppress the temperature rise of the pulverized rubber in the pulverizing step and maintain the straightness of the pulverizing rolls 2a11, 2a12, 2b11, 2b12, 2c11 and 2c12, it is desirable to cool the pulverizing roll.
The preferred roll groove shapes and roll surface speed difference ratios of the rough pulverizing rolls 2a11 and 2a12, the medium pulverizing rolls 2b11 and 2b12, and the finishing pulverizing rolls 2c11 and 2c12 in the fine pulverizer 2 are as shown in Table 1 below.

The classifying and collecting step (B) is a step of classifying and collecting the finely pulverized rubber added with the anti-sticking agent in the finely pulverizing step (A) by the classifier 3.
In the classifying and collecting step, the finished pulverized rubber processed in the finishing pulverization unit 2c is sent to the classifier 3, and is classified into finely pulverized rubber having a predetermined particle diameter and others, and only the finely pulverized rubber having a predetermined particle diameter is used. Is recovered as a finely powdered rubber product in a recovery unit 6 such as a recovery tank, and finely pulverized rubber (non-collected pulverized rubber) exceeding a predetermined particle size is returned to the finish pulverizing unit 2c to be used as finished pulverized rubber again. The grinding is repeated.
Of course, when there are a wide variety of desired particle sizes, the selected finely pulverized rubber having a predetermined particle size and all other particles may be collected as a product.
The metal contained in the non-finely pulverized rubber discharged from the finish pulverizing unit 2c is removed by the metal removing device 2c3 before being returned to the finish pulverizing unit.
As the classifier 3, a sieve or the like is used.

  The manufacturing method shown in FIG. 2 is described on the assumption that the preliminary pulverization step (Y) is provided as part of a series of processing steps, but the preliminary pulverization step (Y) is not necessarily required. Depending on the particle size of the rubber chip, as shown in FIG. 1, the preliminary pulverization step (Y) may be omitted and the rubber chip, which is a raw material of rubber, may be directly fed into the rough pulverization part 2a of the rough pulverization step.

Next, another method for producing powder rubber used in the rubber composition of the present invention will be described with reference to FIGS.
The method for producing the powder rubber shown in FIGS. 3 and 4 is based on the premise of producing the finely crushed rubber shown in FIGS. 1 and 2, and the separation step (Z) is performed between the pulverization step (A) and the classification and recovery step (B). It is added. Therefore, in FIG. 4, the reference numerals attached to FIG. 2 are used as they are for the configuration of the common manufacturing system. Also, description of the steps common to the manufacturing method and the manufacturing method shown in FIG. 1 is omitted.
As shown in FIG. 4, the finely pulverized rubber processed by the finishing pulverization unit 2c is classified into the final finely pulverized rubber by the sieving machine 2c2 and the final finely pulverized rubber (non-finished finely pulverized rubber) that does not satisfy the required particle size. Then, the finished finely pulverized rubber is sent to the separator 4, and the non-finely pulverized rubber is returned to the finish pulverizing unit 2c and processed again. The metal contained in the non-finished finely pulverized rubber is removed by the metal removing device 2c3 before being returned to the finish pulverizing unit 2c.

In the separation step (Z), an impact force is applied to the rubber particles of the finished fine pulverized rubber which are connected to each other by the separator 4 to forcibly separate the pulverized rubber into smaller pulverized rubber. That is, as shown in FIG. 4, the finished finely pulverized rubber processed by the finish pulverizing unit 2c is sent to the separator 4 and separated by the rotation of the separation rotating disk 4a provided in the separation chamber of the separator. Is done. The finely pulverized finish rubber rotates in the circumferential direction in the separation chamber as it rotates, repeatedly hits the separation chamber wall, etc., and the impact force between the rubbers riding on the airflow generated by the separation rotating disk rotating at high speed Friction force contributes to separation.
The separator 4 is charged with an anti-sticking agent, but this charging is selective in the separation process and is not always indispensable.
The rotational speed range (including the peripheral speed range) of the separation rotating disk is appropriately set according to the size and volume ratio of the disk and the desired particle size.
In addition, the amount of the finely pulverized rubber to be supplied to the separator 4 varies depending on the filling rate relative to the volume of the separation chamber, so the optimum filling rate is selected.
The finely pulverized rubber separated by the separator 4 is sent to the classifier 3 and sorted into finely pulverized rubber having a predetermined particle size and other particles, and only the finely pulverized rubber having a predetermined particle size is collected in a recovery tank or the like. Finely pulverized rubber recovered in the recovery unit 6 and exceeding a predetermined particle size is returned to the rough pulverization unit 2a.
According to the manufacturing method shown in FIG. 3 and FIG. 4, the rubber particles connected to each other of the finely pulverized rubber are forcibly separated through the separation step (Z), and the dispersed particles are dispersed. Can be classified efficiently.

Furthermore, another method for producing powder rubber used in the rubber composition of the present invention will be described with reference to FIG.
The method for producing the finely pulverized rubber shown in FIG. 5 is the same as that for finely pulverized means 5 used in the finely pulverized step (A) except that the finely pulverized means 5 is different from the finely pulverized means 2 shown in FIG. It is the same composition as. For this reason, in FIG. 5, the code | symbol attached | subjected to FIG. 4 is used as it is regarding the structure of a common manufacturing system. Further, description of the steps common to the manufacturing method and the manufacturing method shown in FIGS. 3 and 4 is omitted.
In the fine pulverizing means 5, the rough pulverizing part 5a has a fixed blade 5a11 and a rough pulverizing roll 5a12, the intermediate pulverizing part 5b has a fixed blade 5b11 and an intermediate pulverizing roll 5b12, and the finish pulverizing part 5c has a fixed blade 5c11 and a final pulverizing roll 5c12. Each one or more stages are arranged.
On the outer peripheral surfaces of the rough pulverizing roll 5a12, the medium pulverizing roll 5b12, and the finishing pulverizing roll 5c12, uneven surfaces similar to those of the pulverizing rolls 2a11, 2a12, 2b11, 2b12, 2c11, and 2c12 are formed.
The crushed rubber is pulverized by a shearing force at each pulverization stage in each of the fixed blade 5a11 and the rough pulverizing roll 5a12, the fixed blade 5b11 and the medium pulverizing roll 5b12, and the fixed blade 5c11 and the finishing pulverizing roll 5c12.
Sieve machines 5a2, 5b2, 5c2, metal removers 5a3, 5b3, 5c3 and stirrers 5a4, 5b4, 5c4 are sieve machines 2a2, 2b2, 2c2, metal removers 2a3, 2b3, 2c3 and stirrers 2a4, 2b4, 2c4. It corresponds to each.

4 and 5, the pre-grinding step (Y) may be omitted and the rubber chips, which are rubber raw materials, may be directly put into the rough pulverizing sections 2a and 5a.
The illustrated pulverizer 2 is a horizontal type, but may be a vertical type. 2 and FIG. 4, a pair of pulverizing rolls 2a11, 2a12, a pair of pulverizing rolls 2b11, 2b12, and a pair of pulverizing rolls 2c11, 2c12 are respectively provided in the pulverizing units 2a, 2b, 2c of the fine pulverizer 2 shown in FIGS. A plurality of pairs may be arranged in the horizontal direction in the stage, and a plurality of stages of roll crushing may be performed in each stage to improve mass productivity and production efficiency. This can also be applied to the pulverizer 5 shown in FIG. When performing roll pulverization processing in a plurality of stages at each stage, processing conditions such as the groove shape, surface speed difference ratio, and gap of the pulverization roll are changed from the upstream side toward the downstream side. Of course, as in the case of the fine pulverizers 2 and 5 shown in FIG. 2, FIG. 4 and FIG.
In the above-described manufacturing method, the example in which the anti-sticking agent is added to each of the rough pulverizing units 2a and 5a, the intermediate pulverizing units 2b and 5b, and the finish pulverizing units 2c and 5c has been described. In any case, it is selected whether or not to omit the pulverized portion to be charged with the anti-sticking agent depending on the particle size or pulverized state of the pulverized rubber to be obtained.

The powder rubber used in the rubber composition of the present invention may be one containing powder rubber produced by the above-described rubber chip pulverization treatment. Preferably, the powder rubber obtained by the above-mentioned rubber chip pulverization treatment is used. Among them, it is preferable that the powder rubber that has passed through a 100 mesh filter is 75% by mass or more, and more preferably, only powder rubber that has passed through a 100 mesh filter is contained.
More preferably, it is most preferable that the powder rubber that has passed through the 200-mesh filter is 75 mass or more and contains only the rubber that has passed through the 200-mesh filter. Powdered rubber that has passed through a 100-mesh filter has very little possibility of becoming a fracture nucleus, and is particularly effective for suppressing a decrease in fracture strength.

  The content of the powder rubber in the rubber composition of the present invention is preferably 40 parts by mass or less, more preferably 1 to 30 parts by mass with respect to 100 parts by mass of the new rubber. Desirable fracture characteristics can be secured by controlling the content of the powder rubber to 40 parts by mass or less.

The new rubber used in the rubber composition of the present invention is not particularly limited, and various rubbers such as natural rubber and synthetic rubber similar to the rubber component in the powder rubber can be used.
In addition, the rubber composition of the present invention can contain fillers such as carbon black, silica, alumina, aluminum hydroxide, etc. Various chemicals used in the above, for example, vulcanizing agents, vulcanization accelerators, process oils, anti-aging agents, anti-scorching agents, zinc white, stearic acid and the like can be appropriately contained.

The rubber composition of the present invention is manufactured by blending the above-mentioned powdered rubber component and various compounding agents in a predetermined blending ratio with new rubber, and sequentially performing kneading, heating, extrusion, vulcanization, and the like. Can do.
The kneading is preferably carried out by two-stage kneading in which the powder rubber according to the present invention is first kneaded with a new rubber, an anti-aging agent, etc., and then a vulcanizing agent, a vulcanization accelerator, etc. are added and kneaded again. is there. Other conditions are not particularly limited, and various conditions such as the input volume to the kneading apparatus, the rotational speed of the rotor, the ram pressure, the kneading temperature, the kneading time, the type of the kneading apparatus, etc. are appropriately determined according to the purpose. You can choose. Examples of the kneading apparatus include a Banbury mixer, an intermix, a kneader and the like that are usually used for kneading a rubber composition.
The heating conditions are not particularly limited, and the conditions such as the heating temperature, the heating time, and the heating apparatus can be appropriately selected according to the purpose. As a heating apparatus, the roll machine etc. which are normally used for the heating of a rubber composition are mentioned, for example.
Extrusion conditions are not particularly limited, and various conditions such as extrusion time, extrusion speed, extrusion apparatus, and extrusion temperature can be appropriately selected according to the purpose. As an extrusion apparatus, the extruder etc. which are normally used for extrusion of the rubber apparatus for tires are mentioned, for example. The extrusion temperature can be determined as appropriate.
The vulcanization apparatus, method, conditions, etc. are not particularly limited and can be appropriately selected according to the purpose. Examples of the vulcanizing apparatus include a molding vulcanizer using a mold usually used for vulcanizing a rubber composition for tires. The extrusion temperature is usually about 100 to 190 ° C.

  In addition, the pneumatic tire of the present invention may be any tire as long as the rubber composition of the present invention is used as, for example, a tread rubber or the like, and the type of tire, its specific structure, material, etc. are particularly limited. Is not to be done. As an example of a pneumatic tire, although not shown, a pair of speed cores, a carcass connected in a toroidal shape between the speed cores, a belt for tightening a crown portion of the carcass, and a belt disposed on the belt And a tire having a tread rubber. The tire of the present invention may have a radial structure or a bias structure. Also, the production method is not particularly limited, and can be carried out according to conventional methods.

EXAMPLES Next, although an Example demonstrates this invention further in detail, this invention is not limited at all by these examples.
Examples 1-6, Comparative Examples 1-5
As the powder rubber component, only the one that passed through a 100-mesh filter manufactured by the rubber chip pulverization method comprising the preliminary pulverization step (Y), fine pulverization step (A) and classification recovery step (B) shown in FIG. A powder rubber A containing, a powder rubber B containing only the powder rubber A passed through a 200 mesh filter, a commercially available recycled rubber, and a commercially available powder rubber A (24 mesh product) were prepared.

(1) Preparation of rubber composition The above-mentioned waste rubber component and various compounding agents are blended at a blending ratio shown in Table 2 below with respect to 100 parts by mass of styrene butadiene rubber (SBR) as a rubber component of the new material. Then, each rubber composition was obtained by kneading using a 90 cm ³ blast mill. The obtained rubber composition was subjected to pressure vulcanization at 160 ° C. for 13 minutes to obtain vulcanized rubber samples of respective comparative examples and examples. Moreover, the usage-amount of a powder rubber component and sulfur is as having shown in the following Table 3 and Table 4 about each comparative example and the Example, respectively.
The kneading was performed in two steps as follows. That is, first, in the first step, the powder rubber component was kneaded together with SBR, carbon black, softener, stearic acid and anti-aging agent at a maximum temperature of 160 ° C. Subsequently, in the second step, the rubber obtained in the first step, zinc white, vulcanization accelerator A, vulcanization accelerator B, vulcanization accelerator C, and sulfur at a maximum temperature of 105 ° C. Kneaded. In addition, also when mix | blending only new rubber (Comparative example 1 of Table 3), it knead | mixed by the same method except not having added the powder rubber component.

＊１）合成ゴム：ＳＢＲ＃１５００（ＪＳＲ株式会社製）
＊２）カーボンブラック：シースト７ＨＭ（東海カーボン株式会社製）
＊３）老化防止剤：ノクラック６Ｃ（大内新興化学工業株式会社製）
＊４）加硫促進剤A：ノクセラーＤＭ−Ｐ（大内新興化学工業株式会社製）
＊５）加硫促進剤B：ノクセラーＮＳ−Ｐ（大内新興化学工業株式会社製）
＊６）加硫促進剤C：ノクセラーＤ（大内新興化学工業株式会社製）
＊７）硫黄：粉末硫黄

* 1) Synthetic rubber: SBR # 1500 (manufactured by JSR Corporation)
* 2) Carbon black: Seast 7HM (manufactured by Tokai Carbon Co., Ltd.)
* 3) Anti-aging agent: NOCRACK 6C (manufactured by Ouchi Shinsei Chemical Co., Ltd.)
* 4) Vulcanization accelerator A: Noxeller DM-P (Ouchi Shinsei Chemical Co., Ltd.)
* 5) Vulcanization accelerator B: Noxeller NS-P (Ouchi Shinsei Chemical Co., Ltd.)
* 6) Vulcanization accelerator C: Noxeller D (Ouchi Shinsei Chemical Co., Ltd.)
* 7) Sulfur: Powdered sulfur

(2) Measuring method For each vulcanized rubber sample of each comparative example and example obtained, the fracture characteristics (Tb) were measured by the following method to evaluate each rubber composition. In addition, the actual wear resistance of pneumatic tires using each rubber composition was also evaluated according to the following. The obtained results are shown in Tables 3 and 4 below.
(Evaluation method of fracture characteristics)
The fracture strength (Tb) was measured according to JIS K6301, and the value of Comparative Example 1 (not containing a powder rubber component and using only new rubber) was set to 100 and displayed as an index. The larger the value, the better the fracture characteristics.
(Real wear resistance)
Each rubber composition was applied as a tread rubber to produce a pneumatic tire (PSR) for a passenger car having a tire size of 195 / 65R15, and the actual wear resistance was evaluated. The results were displayed as an index with the value of Comparative Example 1 being 100. The higher the number, the better the result.

＊８）市販再生ゴム：２４メッシュ品の粉ゴムより得られた再生ゴム（村岡ゴム工業株式会社製）
＊９）市販粉ゴムＡ：２４メッシュ品（村岡ゴム工業株式会社製）

* 8) Commercial recycled rubber: Recycled rubber obtained from 24 mesh powder rubber (Muraoka Rubber Industrial Co., Ltd.)
* 9) Commercial rubber A: 24 mesh product (Muraoka Rubber Industrial Co., Ltd.)

＊１０）粉末ゴムＡ：１００メッシュのフィルターに掛けて通過したもののみ含む。
＊１１）粉末ゴムＢ：１００メッシュのフィルターに掛けて通過したものを２００メッシュのフィルターにかけて通過したもののみを含む。

* 10) Powdered rubber A: Includes only those passed through a 100 mesh filter.
* 11) Powdered rubber B: Includes only what passed through a 100 mesh filter and passed through a 200 mesh filter.

  As can be seen from the results in Tables 3 and 4 above, the rubber compositions of Examples 1 to 6 containing the powder rubber obtained by the rubber chip pulverization method according to the present invention use only new rubber. Even when compared with the rubber composition of Comparative Example 1, it was confirmed that the rubber composition had excellent fracture characteristics that were inferior. In particular, it can be seen that the rubber composition using the powder rubber B has excellent fracture characteristics. In addition, it was confirmed that the actual wear resistance of the tire of the example using the rubber composition was comparable to that of the comparative example. In particular, it can be seen that the rubber composition using the powder rubber B has excellent wear resistance as well as fracture characteristics.

  The rubber composition of the present invention containing a powder rubber having a very small particle size obtained by the rubber chip pulverization method according to the present invention has excellent rubber properties, maintains particularly high fracture characteristics, and the composition is used as a tire tread. By using it for members such as rubber and side rubber, it is possible to improve the material recycling rate of waste rubber obtained from rubber products such as used tires.

It is a flowchart of the manufacturing method of the pulverized rubber | gum which concerns on this invention. It is a block diagram which shows the manufacturing system for enforcing the manufacturing method of the fine ground rubber | gum which concerns on this invention. It is a flowchart of the manufacturing method of the other finely pulverized rubber | gum which concerns on this invention, Comprising: It is the chart which has abbreviate | omitted the preliminary | backup grinding | pulverization process. It is a block diagram which shows the manufacturing system for enforcing the manufacturing method of the other finely pulverized rubber | gum which concerns on this invention. It is a block diagram which shows the manufacturing system for enforcing the manufacturing method of the further another finely pulverized rubber based on this invention.

Explanation of symbols

1 Pre-grinding machine (pre-grinding means)
2 Fine grinding machine (fine grinding means)
2a Rough grinding part 2a11, 2a12 Rough grinding roll 2a2 Sieve machine 2a4 Stirrer 2b Medium grinding part 2b11, 2b12 Medium grinding roll 2b2 Sieve machine 2b4 Stirrer 2c Finish grinding part 2c11, 2c12 Finishing grinding roll 2c2 Sieve machine 2c4 Stirrer 3 Classification Machine (classification means)
4 Separator (separation means)
5 Fine grinding machine (fine grinding means)
5a Rough crushing unit 5a11 Fixed blade 5a12 Rough crushing roll 5b Medium crushing unit 5b11 Fixed blade 5b12 Medium crushing roll 5c Finish crushing unit 5c11 Fixed blade 5c12 Finish crushing roll 6 Recovery unit

Claims (12)

  A rubber composition containing a powder rubber obtained by finely pulverizing rubber chips, wherein the powder rubber is roughly pulverized while adding an anti-sticking agent to the rubber raw material processed into a chip shape by means of fine pulverization. A fine pulverization step (A) in which coarsely crushed rubber is sequentially finished into finely pulverized rubber by pulverization and finish pulverization, and the finely pulverized rubber is classified and at least a part thereof is recovered as a fine powder rubber product. A rubber composition produced by a finely pulverized rubber treatment method having a classification recovery step (B).   In the fine pulverization step (A), using the roll pulverization means in which a pair of coarse pulverization rolls, a medium pulverization roll and a finish pulverization roll are arranged as fine pulverization means, rough pulverization is performed between the pair of pulverization rolls in each stage. The rubber composition according to claim 1, which is subjected to intermediate pulverization and finish pulverization.   The rubber composition according to claim 2, wherein the outer peripheral surfaces of the pair of rough pulverizing rolls, medium pulverizing rolls, and finish pulverizing rolls are formed as irregular surfaces.   A pair of rough pulverizing rolls, medium pulverizing rolls, and finishing pulverizing rolls are arranged, and the above-mentioned pulverizing rolls have uneven surfaces due to the groove shapes of # 5 to # 20, # 10 to # 30, and # 15 to # 40, respectively. The rubber composition according to claim 3, wherein   The rubber composition according to claim 3 or 4, wherein the surface speed difference ratios of the opposed grinding rolls of the pair of rough grinding roll, medium grinding roll and finish grinding roll are each 1/40 to 1/5.   The rubber according to claim 1, wherein in the fine pulverization step (A), a fixed blade and a pulverization roll are used as fine pulverization means, and rough pulverization, intermediate pulverization and finish pulverization are performed between the fixed blade and the pulverization roll in each stage. Composition.   A preliminary pulverization step (Y) is provided upstream of the fine pulverization step (A), and the rubber raw material is subjected to the fine pulverization step (A) after being finely pulverized by the preliminary pulverization means in the preliminary pulverization step (Y). The rubber composition according to any one of claims 1 to 6.   Subsequent to the fine pulverization step (A), a separation step (Z) is provided. In the separation step (Z), an impact force is applied to the rubber particles contained in the fine pulverization rubber and connected to each other. The rubber composition according to any one of claims 1 to 7, which is forcibly separated.   The rubber composition according to any one of claims 1 to 8, wherein the rubber raw material is a rubber chip having a size of 1 mm to 8 mm.   The rubber composition according to any one of claims 1 to 9, wherein the powder rubber contains 75% by mass or more of a material that has passed through a 100 mesh filter.   The rubber composition according to claim 10, wherein the powder rubber contains 75% by mass or more of what has passed through a 200-mesh filter. A pneumatic tire using the rubber composition according to claim 1.

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