JP2005297478A - Manufacturing method for pneumatic tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method for a pneumatic tire, which can shorten a vulcanizing time without decreasing productivity, in the bladderless vulcanization of an unvulcanized tire with a carcass layer composed of a heat-shrinkable organic fiber cord. <P>SOLUTION: In this manufacturing method for the pneumatic tire, the unvulcanized tire, which is provided with at least one carcass layer composed of the heat-shrinkable organic fiber cord, is set in a mold; only the outside of the unvulcanized tire is heated; and cooling water is supplied to the inside thereof so that the unvulcanized tire can be bladderlessly vulcanized. A rubber, wherein a Mooney viscosity ML (1+4) at 100°C is in the range of 80-120, is used as a coating rubber, on the inside of the inner surface of the tire, of the carcass layer which is positioned in the innermost side of the tire. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for manufacturing a pneumatic tire. More specifically, in bladderless vulcanization of an unvulcanized tire provided with a carcass layer made of a heat-shrinkable organic fiber cord, vulcanization time can be shortened while preventing spread cord. The present invention relates to a method for manufacturing a pneumatic tire.

  The pneumatic tire is vulcanized by inserting an unvulcanized tire into a mold and inserting a bladder (rubber bag) inside the unvulcanized tire, and using steam, heated water, etc. inside the bladder. In general, a heating medium is supplied and inflated so that the unvulcanized tire is pressure-bonded to the inner surface of the mold and the outside of the mold is heated. However, when a bladder is used, energy loss consumed by the bladder is large, and so-called bladderless vulcanization methods have been proposed in which the bladder is omitted to shorten the vulcanization time.

  However, if the carcass cord is made of heat-shrinkable organic fiber cords such as nylon or polyester, using the bladderless vulcanization method, the inner wall surface of the tire is not supported by the bladder. There is a phenomenon (this phenomenon is referred to as a spread code) that floats on the inner wall surface of the tire when shrinking, and there is a problem that the tire quality deteriorates.

  As a measure for preventing the spread cord, there is a vulcanization method in which cooling water is supplied to the inside of the unvulcanized tire to heat only the outside while suppressing the flow of the coat rubber of the carcass layer. However, in this vulcanization method, if the heating temperature is increased by giving priority to shortening the vulcanization time, it becomes difficult to suppress the flow of the coat rubber of the carcass layer, so that it becomes impossible to prevent the spread cord. For this reason, it is necessary to proceed with vulcanization so that the heating temperature is lowered and time is required, so that there is a problem that the energy saving advantage by the bladderless vulcanization method is diminished.

Among the conventionally proposed bladderless vulcanization methods, there is a method in which a resin film is attached to the inner wall surface of an unvulcanized tire to perform vulcanization, although it is not a spread code countermeasure (Patent Document 1). However, although the vulcanization method for lining the resin film is a measure against spread cords, it increases the cost of the material by specially preparing the resin film, and the process of lining the film causes an increase in the number of steps. , Has the disadvantage of reducing productivity.
JP-A-10-180766

  An object of the present invention is to provide a pneumatic tire manufacturing method that can shorten the vulcanization time without reducing productivity in bladderless vulcanization of an unvulcanized tire having a carcass layer made of a heat-shrinkable organic fiber cord. It is to provide.

  The method for producing a pneumatic tire according to the present invention that achieves the above object comprises setting an unvulcanized tire provided with at least one carcass layer made of a heat-shrinkable organic fiber cord in a mold, and placing the unvulcanized tire on the outside In a manufacturing method of a pneumatic tire that is heated only and supplied with cooling water inside and bladderless vulcanized, the Mooney viscosity ML (1 + 4) at 100 ° C. is used as a coat rubber on the inner surface of the tire of the carcass layer located on the innermost side of the tire. It is characterized by using 80 to 120 rubber.

  According to the present invention, in the bladderless vulcanization of an unvulcanized tire provided with a carcass layer made of a heat-shrinkable organic fiber cord, the Mooney viscosity at 100 ° C. is used as a coat rubber on the tire inner surface side of the carcass layer located on the innermost side of the tire. Since high viscosity rubber with ML (1 + 4) of 80-120 is used, the non-fluid action of this high viscosity coat rubber suppresses the spread cord even if the cooling inside the unvulcanized tire is moderated, and the cooling can be mitigated By doing so, the vulcanization time can also be shortened.

  The method for vulcanizing the unvulcanized tire used in the present invention is performed without a bladder. In addition, this bladderless vulcanization method heats only the outside of the unvulcanized tire inserted into the mold, and cools the inside of the unvulcanized tire by supplying cooling water. Suppresses the flow of coat rubber in the carcass layer and prevents spread cords during vulcanization.

  The structure of the mold is not particularly limited, and any conventionally used mold can be used. For example, it may be either a split mold that is divided into left and right in the vicinity of the tire equator, or a sectional mold that is divided into a plurality of tread molding portions in the tire circumferential direction. However, in any case, the characteristic is that no bladder is used.

  FIG. 1 illustrates only the basic portion of an apparatus for vulcanizing an unvulcanized tire. The mold 10 is configured as a split mold of a lower mold 10 a and an upper mold 10 a, and an unvulcanized tire T is set inside the mold 10. A heating unit (not shown) is provided outside the mold 10, and a heating medium such as steam and heated water is supplied to the heating unit to heat the unvulcanized tire T from the outside, thereby vulcanizing from the outside to the inside. Progress towards. On the other hand, a bladder is not inserted inside the unvulcanized tire T, and the inner surface of the unvulcanized tire T is cooled and pressed against the inner surface of the mold 10 by directly supplying pressurized cooling water. By this cooling action, the flow of the coat rubber of the carcass layer is suppressed, and spread cords can be prevented.

  The unvulcanized tire used in the present invention may have one or more carcass layers. It is sufficient if it has at least one carcass layer and the carcass cord is made of a heat-shrinkable organic fiber coat. Further, the tire structure may be a radial tire or a bias tire.

  The material of the heat-shrinkable organic fiber cord constituting the carcass cord is not particularly limited. Preferably, those made of a crystalline polymer such as nylon or polyester are preferred. In general, a crystalline polymer is made into a fiber by a melt spinning method, and the strength is improved by orienting crystals of internal molecules in the fiber axis direction by drawing the fiber after spinning. Because of having such an internal structure, when the organic fiber cord is heated during vulcanization, a part of the oriented crystal structure tries to return to its original state and causes a shrinkage behavior.

  In the unvulcanized tire having the tire structure described above, the innermost carcass layer is formed on the inner rubber of the carcass cord (heat-shrinkable organic fiber cord) at 100 ° C. A rubber having a Mooney viscosity ML (1 + 4) of 80 to 120 is used.

  That is, as shown in FIG. 2, the carcass layer 1 generally has a configuration in which a coat rubber 3 a on the tire inner side and a coat rubber 3 b on the outer side are arranged with the carcass cord 2 interposed therebetween. The innermost layer of the tire is provided with an inner liner 4 made of butyl rubber or the like having low air permeability. The inner rubber 4a at the innermost side of the innermost carcass layer 1 that is in contact with the inner liner 4 is coated at 100 ° C. A rubber having a Mooney viscosity ML (1 + 4) of 80 to 120 is used. The viscosity of the coat rubber on the outer side of the tire is not particularly limited, but it is preferable to use a rubber having a Mooney viscosity ML (1 + 4) lower than that of the coat rubber on the inner side of the tire from the viewpoint of ease of manufacture.

  The coated rubber inside the tire of the carcass layer located on the innermost side of the tire is a rubber having a Mooney viscosity ML (1 + 4) (at 100 ° C) of 80 or more, so that the coated rubber can be used without particularly strengthening the cooling inside the unvulcanized tire. It can be maintained in a non-flowing state, thereby preventing the occurrence of spread codes. Moreover, since it is not necessary to strengthen the cooling inside the unvulcanized tire, the vulcanization time can be shortened. However, if the coated rubber inside the tire is a rubber having a Mooney viscosity ML (1 + 4) (at 100 ° C.) greater than 120, it becomes difficult to calender the carcass layer, thereby making it difficult to form an unvulcanized tire. It becomes like this.

  In the unvulcanized tire used in the present invention, as described above, the coated rubber inside the tire of the carcass layer at the innermost position is composed of rubber having a Mooney viscosity ML (1 + 4) (at 100 ° C.) of 80 to 120. In the case of a pneumatic tire in which two or more carcass layers are provided, Mooney viscosity ML (1 + 4) (at 100 ° C.) is applied to the inner rubber of the second carcass layer. 80-120 rubber is good. By configuring the second carcass layer in this way, the second carcass cord is suppressed from moving to the inside of the tire during vulcanization, and contact with the first carcass cord is prevented. High pneumatic tires can be manufactured.

  Here, Mooney viscosity ML (1 + 4) is a rubber viscosity according to the measurement method defined in JIS K 6300-1, and in particular, using an L-shaped rotor, the preheating time is 1 minute and the rotation time of the rotor is 4 minutes. Viscosity measured under conditions. The Mooney viscosity ML (1 + 4) at 100 ° C. means the viscosity measured at a rubber temperature of 100 ° C.

  In the present invention, the heating performed from the outside of the unvulcanized tire is performed by supplying a heating medium such as steam or heated water to the mold, and the heating temperature is preferably 130 to 180 ° C. Moreover, it is preferable that the temperature of the cooling water supplied to the inner side of an unvulcanized tire shall be 10-100 degreeC. More preferably, the outer heating temperature is in the range of 140 to 180 ° C., the temperature of the inner cooling water is 50 to 100 ° C., and the cooling is moderated, thereby further shortening the vulcanization time without causing spread code. It becomes possible.

  A common condition is that the tire size is 280 / 680R18 and a carcass layer having a nylon fiber cord as a carcass cord is provided, and the Mooney viscosity ML (1 + 4) of the coat rubber inside the tire and the coat rubber outside the tire of the carcass layer ( 5 unvulcanized radial tires having different temperatures at 100 ° C. as shown in Table 1 were produced. Of the five unvulcanized tires, the unvulcanized tires of the conventional example and the comparative example 1 have the same structure of the coated rubber. Further, in Comparative Example 3, molding was impossible because the viscosity of the coat rubber inside the tire was too high.

  Five unvulcanized radial tires excluding the above Comparative Example 3 are set in a mold, steam is heated to 150 ° C. on the outside and heated, and cooling water is supplied on the inside to release temperature. The temperature was adjusted to 50 ° C., and the vulcanization time was varied as shown in Table 1 to perform vulcanization molding without a bladder. In Table 1, the vulcanization time is indicated by an index with the vulcanization time of the conventional example as 100.

  The five pneumatic tires after vulcanization were examined for the presence of spread cords on the inner wall surfaces of the tire, and the results shown in Table 1 were obtained.

  From the results in Table 1, it can be seen that in Examples 1 and 2, high-quality tires without spread codes can be obtained while shortening the vulcanization time compared to the conventional example.

It is explanatory drawing which illustrates the relationship between the metal mold | die in the manufacturing method of the pneumatic tire of this invention, and the unvulcanized tire inserted in the metal mold | die. It is sectional drawing which illustrated the tire inner wall vicinity vicinity of the unvulcanized tire used for this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Carcass layer 2 Carcass cord 3a Coat rubber (inside of tire) 3b Coat rubber in (outside of tire) 10 Mold T Unvulcanized tire

Claims (3)

  An unvulcanized tire having at least one carcass layer made of heat-shrinkable organic fiber cord is set in a mold, the unvulcanized tire is heated only on the outside, and cooling water is supplied on the inside to perform bladderless vulcanization. In the manufacturing method of a pneumatic tire, the manufacturing method of the pneumatic tire which uses the rubber | gum whose Mooney viscosity ML (1 + 4) in 100 degreeC is 80-120 as coat rubber of the tire inner surface side of the carcass layer located in the tire innermost side.   2. The air according to claim 1, wherein a plurality of the carcass layers are provided, and rubber having a Mooney viscosity ML (1 + 4) at 100 ° C. of 80 to 120 is used as a coat rubber on the tire inner surface side of the second carcass layer from the inside of the tire. A method for manufacturing a tire. The manufacturing method of the pneumatic tire of Claim 1 or 2 which made the temperature of the said unvulcanized tire outer side temperature 130-180 degreeC, and made the temperature of the cooling water supplied to the said inside 10-100 degreeC.

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