JP4735812B2 - tire - Google Patents

Description

  The present invention relates to a tire in which a constituent member of a sidewall portion is formed by a so-called ribbon lamination method, and further, a crack is hardly generated in the sidewall portion.

  Today, the required performance for rubber products such as tires is becoming increasingly sophisticated and diversified. Rubber products that meet such demanded and diversified performance are often provided as rubber composites in which rubber members having various shapes are combined.

  Here, the rubber member is generally obtained by molding an unvulcanized rubber in a mold and then vulcanizing it. However, molding using the mold tends to enlarge the apparatus, and it has a complicated shape. Since the mold for obtaining the rubber member having the above is expensive, the manufacturing cost tends to increase. In particular, when a large variety of small lots is required, a mold must be prepared each time, and in such a case, the manufacturing cost of the rubber member becomes higher.

  A so-called ribbon laminating method has been proposed as a molding method capable of meeting the demands for downsizing the manufacturing apparatus for rubber members and reducing manufacturing costs. For example, in Patent Document 1: Japanese Patent Publication No. 7-94115 and Patent Document 2: Japanese Patent Application Laid-Open No. 2002-160508, a discharge port of a constant volume extruder is positioned near a rotating support, and the discharge port is moved. A rubber member molding method capable of freely changing the cross-sectional shape of the rubber member by directly extruding the rubber composition from the discharge port onto the support (forming and laminating a belt-like “ribbon”), or the like A method for molding a tire using a rubber member is described.

  As a method for improving the adhesion between different types of ribbons, Patent Document 3: Japanese Patent Application Laid-Open No. 2000-79643 discloses that a rubber composition is pressed onto a rotating support while controlling the blending ratio of two or more rubber raw materials. A method for laminating a strip-shaped unvulcanized rubber that reduces the modulus difference between adjacent ribbons and secures close contact between the ribbons is described.

  Furthermore, as a method for further improving the production efficiency of the ribbon laminating method, Patent Document 4: Japanese Patent Application Laid-Open No. 2003-145603 includes a rubber composition A composed of a compounding system excluding a vulcanizing agent and a vulcanization accelerator. The scorch is also formed by excessive frictional heat generated when trying to increase the molding speed by increasing the extrusion speed by molding the ribbons from the rubber composition B consisting of the excluded blending system and laminating them alternately. It is described that a method for producing an unvulcanized rubber member that does not occur and has high molding efficiency can be realized.

  However, the advantages of the ribbon lamination method, that is, the use of a combination of a small extruder with a die having a small-diameter discharge port and a rotating support, eliminates the need for a mold or large injection molding machine. It is considered unpreferable from the viewpoint of interfacial delamination between ribbons that the advantage of the ribbon laminating method that space can be reduced and manufacturing costs can be reduced. That is, since the heater band used in a small extruder usually has a small heat capacity corresponding to the extruder, the heating into the extruder tends to be insufficient. In such a case, when the unvulcanized rubber is molded, the viscosity is not sufficiently lowered, the adhesion between the ribbons is insufficient, and peeling at the lamination interface is likely to occur.

  In particular, when considering tires that require durability under harsh conditions, the adhesion between the laminated ribbons is fully maintained over a long period of time, and tire cracks are caused by peeling at the ribbon lamination interface. Is required not to occur. The location where the greatest bending strain occurs when a load is applied to the tire is, for example, the vicinity of the sidewall portion, but from the viewpoint of not causing tire cracks due to separation of the ribbon lamination interface, there is a reduction in manufacturing cost, etc. Even in the present situation where the above-described ribbon lamination method is known, a molding method using a mold has been adopted when manufacturing a rubber member constituting the sidewall portion.

  A technology that makes it possible to realize a tire having durability comparable to that of conventional tires even if the members of the sidewall portion of the tire are formed using a ribbon laminating method that has advantages from the viewpoint of manufacturing cost and the like. Development was required.

Japanese Patent Publication No. 7-94115 JP 2002-160508 A JP 2000-79643 A JP 2003-145603 A

  The present invention has been made in view of the above circumstances, and even when a ribbon laminating method that is advantageous in terms of manufacturing cost and the like is used in forming the constituent members of the sidewall portion of the tire, the ribbons are in close contact with each other. An object of the present invention is to provide a tire that sufficiently secures the tire and thus has sufficient durability (no cracking is likely to occur).

In order to achieve the above object, the present inventor provides the following tires.
Claim 1:
The unvulcanized rubber composition is extruded into a band shape by an extruder, and the band-like body is partially or entirely superimposed on a rotating support that rotates the band-like body from one side in the axial direction to the other side. Mooney viscosity (ML) measured in accordance with JIS K 6300: 2001 of the unvulcanized rubber composition, which is a tire using a laminated rubber member by a ribbon lamination method formed by winding as described above as a sidewall portion. _{1 + 4} (130 ° C.) is 40 to 70.
Claim 2:
The tire according to claim ₁ , wherein the Mooney viscosity is 40 ≦ ML _{1 + 4} (130 ° C.) ≦ 60.

  ADVANTAGE OF THE INVENTION According to this invention, the tire which has durability comparable to the conventional tire manufactured using the metal mold | die, and is excellent in manufacturing cost is provided.

Hereinafter, the present invention will be described in more detail with reference to the drawings.
FIG. 1 is a left half sectional view of a tire 10 showing an example of the tire according to the present invention by a plane including a rotation axis. In FIG. 1, the tire 10 has a pair of bead portions 11 (only one side is shown), a pair of sidewall portions 12 (only one side is shown), and a tread portion 13. The tire 10 also includes a bead core 14 embedded in the bead portion 11 and a radial carcass 15 that embeds the bead core 14 in the bead portion 11 and reinforces the portions 11, 12, and 13 in series. Further, the tire 10 has a chafer rubber 16 in the bead portion 11, a sidewall rubber 17 in the sidewall portion 12, and a tread rubber 18 in the tread portion 13 as outer rubber members on the outer wall surface side. On the other hand, an inner liner rubber 19 is provided on the inner wall surface side of the tire 10 as an inner rubber member.

The tread rubber 18 has a multi-layer structure in which a tread undercushion rubber 21 for securing adhesion to the radial carcass 15 is an innermost side, a tread base rubber 22 is an intermediate layer, and a tread cap rubber 23 is an outermost layer. .
In the bead portion 11, the radial carcass 15 has a bead filler rubber 20 that fills a gap between the radial carcass 15 and the bead core 14 embedded therein.

  FIG. 2 shows that a band formed by extruding an unvulcanized rubber composition by an extruder is partially or entirely overlapped on a rotating support from the one side in the axial direction to the other side. It is sectional drawing which shows a mode that the said strip | belt-shaped body is laminated | stacked so that the laminated rubber member which may be wound as mentioned above and may have desired cross-sectional shape will be obtained. The laminated rubber member shown in FIG. 2 starts to be wound around a rotating support (not shown) from the right side of the drawing, spirally winds the belt-like rubber A at a relatively small feed pitch p, and further reduces the belt-like rubber B to the same small size. The belt is spirally wound on the belt-like rubber A at a feed pitch p.

In the tire of the present invention, a laminated rubber member as shown in FIG. 2 is used as a rubber member constituting the sidewall portion, for example, as a rubber member constituting the sidewall portion 12 (sidewall rubber 17) in the tire 10. Tire.
In general, a very large bending strain occurs in the tire sidewall when a load is applied to the tire. Therefore, when forming the components of the sidewall, the possibility of interfacial delamination between the ribbons is denied. It was difficult to adopt the conventional ribbon lamination method.
However, since an unvulcanized rubber composition having a specific viscosity is used in the present invention, the risk of interfacial peeling between ribbons can be reduced as much as possible. Therefore, the ribbon laminating method can also be adopted when manufacturing the constituent parts of the sidewall portion, which has conventionally been difficult to adopt the ribbon laminating method, not only realizing further reduction in the manufacturing cost of the tire, but also the tire obtained is conventional Compared with the tires of the above, it has durability comparable to that of the tire.

As the unvulcanized rubber composition in the present invention, a rubber composition having a Mooney viscosity (ML _{1 + 4} (130 ° C.)) of 70 or less, preferably 40 to 60, more preferably 45 to 55 is used. By setting the Mooney viscosity of the unvulcanized rubber composition within this range, sufficient fluidity of the unvulcanized rubber is ensured even when using a small extruder that may be insufficiently heated. When the strips of the unvulcanized rubber composition are laminated, the adjacent strips can be satisfactorily adhered to each other, thereby achieving the object of the present invention. If the Mooney viscosity is too large, sufficient adhesion at the laminated interface of the strips is not ensured when the heating is insufficient, and the object of the present invention is not achieved. On the other hand, if it is too small, rubber may stick to the vicinity of the die of the extruder during ribbon lamination of the sidewall portion, and ribbon lamination may not be performed well. Further, when the Mooney viscosity is low due to the low molecular weight of the rubber polymer, the durability of the formed sidewall portion may be inferior.

  In the present invention, “insufficiently heated” means that the temperature of the unvulcanized rubber does not rise sufficiently and the fluidity of the unvulcanized rubber is insufficient.

In the present invention, the “Mooney viscosity” is an industrial viscosity index measured with a Mooney viscometer, which is a kind of a rotary plasticity meter (based on JIS K 6300-1: 2001), and a compounded rubber viscosity. It is an index often used in the rubber industry for the measurement of. When the compound rubber is hermetically filled in the gap formed by the cylindrical die and the rotor at the center, and the rotor is rotated at a test temperature of 130 ° C., a preheating time of 1 minute, a rotor rotation time of 4 minutes, and a rotation speed of 2 rpm. Is obtained from the torque value generated in The unit symbol is ML _{1 + 4} (130 ° C.) {where M is Mooney viscosity, L is the shape of the rotor and represents the large rotor (L shape), (1 + 4) is the preheating time of 1 minute, and the rotor rotation time is 4 Minutes represent 130 ° C. represents the test temperature. } Is used.

Here, the method for adjusting the Mooney viscosity is not particularly limited. For example, (i) rubber kneading conditions when kneading each raw material of an unvulcanized rubber composition described later using a Banbury mixer A method of adjusting (kneading time, raw material falling temperature at the time of blending, number of kneading times, raw material filling rate in the mixer),
(Ii) A method of adjusting the blending amount of carbon black or plasticizer among the raw materials of the unvulcanized rubber composition described later,
Is mentioned.

The unvulcanized rubber composition in the present invention is not particularly limited except that the Mooney viscosity is in the above range, but usually a vulcanizing agent, a vulcanization accelerator, various additives and the like are mixed with the rubber component. Composition.
Examples of the rubber component include natural rubber, ethylene / propylene / diene rubber (EPDM), styrene / butadiene copolymer rubber (SBR), butadiene rubber, isoprene rubber, butyl rubber, halogenated butyl rubber, isobutylene and p-halogenated methylstyrene. And acrylonitrile / butadiene copolymer rubber (NBR). These may be used singly or in combination of two or more.
Among these, from the viewpoint of durability and low heat build-up, it is preferable to employ rubber containing natural rubber and / or isoprene rubber in a proportion of 50% by mass or more as the rubber component.

  Examples of the vulcanizing agent include sulfur. The amount used is usually 0.1 to 10 parts by mass with respect to 100 parts by mass of the rubber component.

Examples of the vulcanization accelerator include CBS (N-cyclohexyl-2-benzothiazylsulfenamide), TBBS (Nt-butyl-2-benzothiazylsulfenamide), TBSI (Nt-butyl- Sulfenamide vulcanization accelerators such as 2-benzothiazylsulfenimide), guanidine vulcanization accelerators such as DPG (diphenylguanidine), and thiuram additions such as tetraoctyl thiuram disulfide and tetrabenzyl thiuram disulfide. Examples thereof include vulcanization accelerators and vulcanization accelerators such as zinc dialkyldithiophosphate, among which CBS and TBBS are preferable. These may be used alone or in combination of two or more.
The amount used is usually 0.1 to 10 parts by mass with respect to 100 parts by mass of the rubber component.

  Examples of the various additives include vulcanization accelerators, fillers, anti-aging agents, zinc white (ZnO), waxes, antioxidants, foaming agents, plasticizers, lubricants, tackifiers, UV absorbers, and the like. Can be mentioned.

  Examples of the vulcanization acceleration aid include stearic acid.

  Examples of fillers include inorganic fillers such as carbon black, silica, fine particle magnesium silicate, heavy calcium carbonate, magnesium carbonate, clay, talc; high styrene resin, coumarone indene resin, phenol resin, lignin, modified melamine resin And organic fillers such as rosin derivatives, among which carbon black and silica are preferred. These may be used alone or in combination of two or more. The amount used is usually 30 to 100 parts by mass with respect to 100 parts by mass of the rubber component.

Examples of the carbon black include carbon blacks such as SRF, GPF, FEF, HAF, ISAF, SAF, FT, and MT. Among these, FEF and HAF are preferable. These may be used alone or in combination of two or more.
Moreover, as a compounding quantity of the said carbon black, it is 30-100 mass parts normally with respect to 100 mass parts of said rubber components, Preferably it is 50-80 mass parts. If the blending amount of the carbon black is less than 30 parts by mass, the breaking strength of the obtained sidewall part may be inferior. On the other hand, if it exceeds 100 parts by mass, the kneading workability may be remarkably lowered.

  Examples of the plasticizer include process oils such as aromatic oils, naphthenic oils, and paraffin oils commonly used for rubbers; vegetable oils such as palm oils; synthetic oils such as alkylbenzene oils, and the like. Paraffin oil is preferred. These may be used alone or in combination of two or more. The amount of use is usually 0 to 20 parts by mass, preferably 1 to 5 parts by mass with respect to 100 parts by mass of the rubber component.

When obtaining the said unvulcanized rubber composition in this invention, there is no restriction | limiting in particular in the compounding method of said each component. All the component raw materials may be blended and kneaded at once, or the components may be blended and kneaded in two or three stages. For kneading, a known kneader such as a roll, an internal mixer or a Banbury mixer (Banbury rotor) can be used.
Moreover, as conditions for vulcanizing the above-mentioned unvulcanized rubber composition obtained by blending each component in this way, vulcanization conditions of usually 5 to 80 minutes at 130 to 180 ° C. can be adopted. .

  In the present invention, the unvulcanized rubber composition is usually plasticized at a temperature lower than the vulcanization temperature, extruded by an extruder, and wound on a rotating support in the form of a strip. Here, the plasticizing temperature is usually 80 to 140 ° C, preferably 100 to 130 ° C.

  In the present invention, the rotating support includes a molding drum, a molding intermediate body in which a part of an unvulcanized rubber member, an unvulcanized rubber-coated cord, and the like are wound on the molding drum, and a retreading tire. The molding drum includes an ordinary cylindrical drum and an annular (toroidal) segment assembly that is separable in the circumferential direction.

  In the present invention, the laminated rubber member is formed by laminating mutually plasticized strips. Here, “lamination” means a state in which at least a part of the belt-like bodies overlap and overlap each other, and the degree of overlap is appropriately set so that a desired cross-sectional shape of the laminated rubber member is realized. .

  EXAMPLES Hereinafter, although an Example and a comparative example are shown and this invention is demonstrated concretely, this invention is not restrict | limited to the following Example.

Examples 1 and 2 and Comparative Examples 1 and 2
Each raw material component was kneaded in a Banbury mixer by blending shown in Table 1 (the numerical values of each component are all parts by mass) and the viscosity adjusting method to obtain an unvulcanized rubber composition. The ML of the obtained rubber composition is also shown in the table.
This unvulcanized rubber composition was extruded onto a molding drum under the conditions shown in the table to produce a laminated rubber member having a cross-sectional shape corresponding to the sidewall rubber 17 in FIG.
Using this laminated rubber member, a tire (225 / 45R17) having the configuration of FIG. 1 was prepared. Performance evaluation of the obtained tire was performed. The evaluation results are also shown in Table 1.

NR
Natural rubber. RSS3.
BR
Polybutadiene rubber. Product name BR01 manufactured by JSR Corporation.
C / B
Carbon black. Asahi Carbon Co., Ltd., trade name Asahi # 60.
Zinc Hana Mitsui Mining Co., Ltd., trade name: Zinc oxide
Aroma oil Idemitsu Kosan Co., Ltd., trade name Diana Process Oil AH-58.
Anti-aging agent manufactured by Sumitomo Chemical Co., Ltd., trade name Antigen 6C.
Product name Suntite R, manufactured by Wax Seika Co., Ltd.
Vulcanization accelerator, Ouchi Shinsei Chemical Co., Ltd., trade name Noxeller NS-F.
Viscosity adjusting method A: Number of kneading times when each raw material is kneaded in a Banbury mixer = 4 times.
B: Number of kneading times when each raw material is kneaded in a Banbury mixer = 5 times.
C: Number of kneading times when each raw material is kneaded in a Banbury mixer = 2 times.
D: Number of kneading times when each raw material is kneaded in a Banbury mixer = 3 times.

Unvulcanized ML of rubber composition
Measured value of ML _{1 + 4} (130 ° C.) measured after blending and kneading each raw material.
Set processing temperature Processing temperature input to the extruder (extrusion screw and base are set to the same temperature).
Vulcanization temperature Maximum temperature on the tire sidewall surface during vulcanization performed on the entire tire after bonding the rubber members.

Drum mileage JIS D4230 63 Using a device conforming to the drum test device in the durability test, the tire is rotated on the drum set to an internal pressure of 100 kPa, a load of 600 kg, and a speed of 60 km / h, and the ribbon is laminated on the side wall. The distance traveled until the occurrence of cracks was measured. It was evaluated as "complete" with 20000km. In addition, the drum travel distance is 18000 km or more when the sidewall rubber is formed without using the ribbon laminating method and evaluated in the same manner as in the above example.

It is a left half sectional view by the plane containing the axis of rotation of the tire which shows an example of the present invention. It is sectional drawing of the laminated rubber member which laminated | stacked the strip | belt body of the unvulcanized rubber composition.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Tire 11 Bead part 12 Side wall part 13 Tread part 14 Bead core 15 Radial carcass 16 Chafer rubber 17 Side wall rubber 18 Tread rubber 19 Inner liner rubber 20 Bead filler rubber 21 Tread under cushion rubber 22 Tread base rubber 23 Tread cap rubber A, B Rubber material p Feed pitch

Claims (2)

The unvulcanized rubber composition is extruded into a band shape by an extruder, and the band-like body is partially or entirely superimposed on a rotating support that rotates the band-like body from one side in the axial direction to the other side. Mooney viscosity (ML) measured in accordance with JIS K 6300: 2001 of the unvulcanized rubber composition, which is a tire using a laminated rubber member by a ribbon lamination method formed by winding as described above as a sidewall portion. _{1 + 4} (130 ° C.) is 40 to 70. The tire according to claim ₁ , wherein the Mooney viscosity is 40 ≦ ML _{1 + 4} (130 ° C.) ≦ 60.

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