JP2007237903A - Run-flat tire supporter and manufacturing method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a run-flat tire supporter having a low modulus of elasticity and low stress under initial strain during an early stage of starting a run flat traveling, capable of clearing a bump shock test for specifying shocks generated on bumps in a road surface, and a manufacturing method thereof. <P>SOLUTION: This run-flat tire supporter 10 made of an elastic body includes an outer circumferential portion 14, an inner circumferential portion 12 having an inner circumferential surface contacting with a rim, and a rib portion 16 for connecting the outer circumferential portion and the inner circumferential portion. The elastic body is a polyurethane elastic body in which isocyanate prepolymer composed of polyether glycol and aromatic diisocyanate is reacted and cured using at least one kind of bis(methylthio)toluene diamine out of 3,5-bis(methylthio)-2,4-toluene diamine and 3,5-bis(methylthio)-2,6-toluene diamine as a chain extender. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a run-flat tire support that is mounted on a rim of an automobile tire, is disposed inside a pneumatic tire, maintains a tire outer diameter necessary when the tire is punctured, and can run safely, and its It relates to a manufacturing method.

  Runflat tires can withstand the load and travel of the vehicle until it reaches the nearest service facility, even if the tire is punctured or if the tire pressure drops significantly or becomes zero. It is a tire with durability. As run-flat tires, a side reinforcing type in which the side portion of the tire is reinforced and a core type in which a support (core) is accommodated inside the tire are put into practical use.

  As a core type run-flat tire support, a support having a polyurethane elastic body as a constituent material is known (for example, Patent Documents 1 and 2).

  The run-flat tire support disclosed in Patent Document 1 is made of a polyurethane elastic body mainly molded by RIM molding for the purpose of providing a support having a small temperature dependency of characteristics and a short manufacturing time. Specifically, MDI is used as the polyisocyanate component, and diethyltoluenediamine is used as the most preferred chain extender.

  The run-flat tire support disclosed in Patent Document 2 is characterized by a cross-sectional shape for the purpose of reducing damage to the tire inner surface in a puncture state and improving ride comfort. A support comprising a polyurethane elastic body obtained by reacting a prepolymer comprising tetramethylene glycol and toluene diisocyanate with methylene bis-o-chloroaniline is disclosed.

Special table 2003-519699 gazette JP-A-6-305310

  However, the run-flat tire equipped with the run-flat tire support described in Patent Documents 1 and 2 has a large elastic modulus and low strain stress during run-flat running when actually running in the run-flat state. It has been found that the shock absorbing performance is not sufficient, and in particular, it is impossible to clear the step impact test that defines the impact generated at the road step and the durability test in run-flat running.

  In view of such circumstances, the present invention provides a run-flat tire that has a lower elastic modulus and low-strain stress during run-flat travel than conventional ones and can clear a step impact test that defines an impact that occurs at a step on a road surface. It aims at providing a support body and its manufacturing method.

The run flat tire support of the present invention comprises an outer peripheral portion, an inner peripheral portion having an inner peripheral surface in contact with the rim, and a rib portion connecting the outer peripheral portion and the inner peripheral portion, and is formed of an elastic body. And
The elastic body is composed of an isocyanate prepolymer composed of polyether glycol and aromatic diisocyanate, 3,5-bis (methylthio) -2,4-toluenediamine, and 3,5-bis (methylthio) -2,6-toluenediamine. It is a polyurethane elastic body obtained by reactive curing using at least one (bis (methylthio) toluenediamine) as a chain extender.

  The run-flat tire support having such a structure has the necessary rigidity and light weight, and has a lower elastic modulus and low-strain stress during run-flat travel than a conventional step, and defines a step that defines an impact generated at a step on the road surface. The durability test in the impact test and the run flat running can be cleared.

  The polyurethane elastic body constituting the run-flat tire support preferably has a hardness of 25 or more and 60 or less, more preferably 35 or more and 55 or less in terms of JIS D hardness (durometer D hardness).

  When the hardness of the polyurethane elastic body is less than 25 in JIS D hardness, the load resistance is not sufficient, and when it exceeds 60, it becomes difficult to attach the elastic body to the rim.

  In the run flat tire support described above, it is preferable to further contain diethyltoluenediamine as a chain extender so as to be 30 mol% or less in the total amount of the chain extender.

  The run-flat tire support having such a configuration has an elastic modulus and low-strain stress during run-flat running that are smaller than conventional ones and excellent in rigidity.

  In the run flat tire support described above, it is preferable that a reinforcing cord layer including a reinforcing cord is provided on the inner peripheral portion in the rim circumferential direction.

  In the run-flat tire support body having such a structure, the movement of the position on the rim due to the expansion of the inner diameter of the support body is prevented by centrifugal force during normal running of the run-flat tire equipped with the support body. .

Another aspect of the present invention is an inner peripheral portion having an outer peripheral portion and an inner peripheral surface in contact with the rim, and having a reinforcing cord layer including a reinforcing cord in the rim peripheral direction, and a rib portion connecting the outer peripheral portion and the inner peripheral portion. A method for producing a run-flat tire support formed of an elastic body,
A reinforcing cord layer forming step for supplying a reinforcing cord to the outer periphery of the mold forming surface that forms the inner peripheral surface, and a reactive composition that forms a polyurethane elastic body is supplied to the molding cavity of the die to be reacted and cured. Having a curing step,
The reactive composition includes an isocyanate prepolymer composed of polyether glycol and aromatic diisocyanate, 3,5-bis (methylthio) -2,4-toluenediamine, 3,5-bis (methylthio) -2,6- It is a mixture of at least one kind of toluenediamine (bis (methylthio) toluenediamine) as a chain extender.

  According to the manufacturing method having such a configuration, the step impact that defines the impact generated at the step of the road surface is provided with the necessary rigidity and light weight, and the elastic modulus and low strain stress during the run flat running are smaller than those of the conventional one. A run-flat tire support that can clear the test and the durability test in the run-flat running can be manufactured.

  In the above method for producing a run-flat tire support, it is preferable to further contain diethyltoluenediamine as a chain extender so as to be 30 mol% or less in the total amount of the chain extender.

  According to the manufacturing method having such a configuration, it is possible to manufacture a run-flat tire support body that has an elastic modulus and low-strain stress during run-flat running that are smaller than those of conventional ones and that has excellent rigidity.

  The polyurethane elastic body constituting the run-flat tire support of the present invention includes an isocyanate prepolymer comprising polyether glycol and aromatic diisocyanate, 3,5-bis (methylthio) -2,4-toluenediamine, 3,5- It is formed using at least one of bis (methylthio) -2,6-toluenediamine (bis (methylthio) toluenediamine) as a chain extender.

  As the aromatic diisocyanate, MDI such as diphenylmethane-4,4′-diisocyanate and isomers thereof, TDI such as 2,4-toluene diisocyanate and 2,6-toluene diisocyanate, naphthalene diisocyanate (NDI) and the like can be used. However, it is preferable to use 2,4-toluene diisocyanate or a mixture of 2,4-toluene diisocyanate and 2,6-toluene diisocyanate. As a mixture of 2,4-toluene diisocyanate and 2,6-toluene diisocyanate, the strength of the resulting polyurethane elastic body is excellent, so the 2,4-TDI / 2,6-TDI ratio (mol) is 60 or more. It is preferable that it is, and it is more preferable that it is 80 or more.

  Examples of the polyether glycol include polypropylene glycol and polytetramethylene glycol, but it is preferable to use polytetramethylene glycol because a polyurethane elastic body having excellent strength is formed.

  The isocyanate prepolymer is produced by reacting polyether glycol and a diisocyanate compound at an NCO / OH equivalent ratio of 1.6 to 2.5.

  When 3,5-bis (methylthio) -2,4-toluenediamine and 3,5-bis (methylthio) -2,6-toluenediamine are used in combination as chain extenders, the mixing ratio is 2,4. It is preferable that it is 60 / 40-95 / 5 (mol ratio) in the ratio of body / 2,6 body. It is also preferable to use a commercially available product as a mixture within this range, and Etacure 300 (2,4 / 2,6-body ratio = 80/20: Albemarle) is exemplified as a suitable commercially available product.

  As the reinforcement cord constituting the reinforcement cord layer, a known reinforcement cord can be used without limitation. Examples thereof include polyamide cords such as nylon 66, polyester cords such as polyethylene terephthalate, aramid cords, steel cords, glass fibers, and carbon fibers. The reinforcing cord may be a monofilament. These reinforcing cords are preferably used after being subjected to an adhesion treatment for improving the adhesion to the elastic body. Among these, the use of an aramid cord is particularly preferable because it is lightweight and provides a sufficient reinforcing effect with a small arrangement density.

  FIG. 1 is a perspective view illustrating a run-flat tire support of the present invention, and FIG. 2 is a cross-sectional view taken along the line XX of FIG. The run-flat tire support 10 has a ring shape with a square cross section, and an outer peripheral portion 14 that contacts the inner surface of the tire during run-flat travel, an inner peripheral portion 12 that has an inner peripheral surface 13 that contacts the rim, and an outer peripheral portion 14 and an inner periphery. The circumferential direction rib part 16 and the circumferential direction rib part 20 which connect the part 12 are comprised, and the reinforcement cord layer 22 is provided in the circumferential direction in the vicinity of the inner peripheral surface of the inner peripheral part 12. The width direction rib part 16 and the circumferential direction rib part 20 are formed of the recessed part 18 provided in the side part of the run flat tire support body. The shape and the number of the recesses 18 are not particularly limited as long as the support 10 satisfies a request such as a predetermined mechanical strength. Although FIG. 1 shows an example in which the side view shape is a fan shape and the cross-sectional shape in the width direction is rectangular, it may be hemispherical. As the volume ratio of the recesses 18 increases, the weight of the support 10 can be reduced.

  Further, the inner peripheral surface of the run-flat tire support 10 is provided with a ridge 25 that fits into a fixed groove formed on the outer peripheral surface of the rim to prevent the support from moving more effectively. . The cross-sectional shape of the ridge 25 is not particularly limited, but a semicircular shape is preferable. The height of the ridges 25 is preferably 1 to 4 mm, and more preferably 1 to 3 mm. If the height of the ridges is too low, the effect of preventing the movement of the support may not be sufficient, and if it is too high, it may be difficult to attach the support to the rim. A plurality of ridges may be provided.

  In the example shown in FIGS. 1 and 2, the circumferential rib 20 is provided on the side portion of the support 10, but the position of the circumferential rib 20 is not limited and may be a central portion. When the position of the circumferential rib 20 is the central portion, the recess 18 is formed on both side surfaces of the support 10.

  The reinforcing cord layer 22 is preferably configured by providing a reinforcing cord and a reinforcing fiber layer on the inner peripheral surface side of the reinforcing cord. The reinforcing fiber layer prevents the reinforcing cord from coming into direct contact with the rim, so that the reinforcing cord protects the reinforcing cord from damage caused by friction with the rim generated during traveling, and the rigidity of the reinforcing cord layer is supplementary. Has an enhancing effect. The reinforcing fiber layer may be formed by winding spun yarn or monofilament in the circumferential direction, or may be formed by winding a woven fabric or net.

  The run flat tire support described above preferably has a width of 25% or more and 50% or less of the bead width of the tire.

  When the width of the run-flat tire support is less than 25% of the tire bead width, the weight reduction effect of the support is excellent, but the running stability in the run-flat state decreases, and exceeds 50%. In this case, the running stability in the run-flat state is improved, but the weight reduction effect is not satisfactory. The width of the support is designed according to the bead width.

[Example of production of run-flat tire support]
Example 1
Adiprene L-167 (unipolymer) of an isocyanate group-terminated prepolymer obtained by reacting polytetramethylene glycol (bifunctional, average molecular weight 1000) with TDI (2,4-TDI 100%) at an NCO / OH ratio of about 2. (Royal: NCO group concentration = 6.41 wt%) 5000 parts by weight are degassed under reduced pressure in advance and adjusted to a temperature of 80 ° C. Etacure 300 (a mixture of 3,5-bis (methylthio) -2,4-toluenediamine and 3,5-bis (methylthio) -2,6-toluenediamine having a liquid temperature of 25 ° C. was added to this isocyanate group-terminated prepolymer. Albemarle) 732 parts by weight was added and stirred to form a reactive composition, which was then poured into a mold preheated to 100 ° C. Thereafter, it was cured by heating in an oven at 100 ° C. for 1 hour, and then demolded, and further post-cured in an oven at 100 ° C. for 16 hours to prepare a run-flat tire support. Table 1 shows the evaluation results of the obtained run-flat tire support having the shape illustrated in FIG.

(Example 2)
Adiprene L-167 of an isocyanate group-terminated prepolymer (NCO / OH ratio is about 2) obtained by reacting polytetramethylene glycol (bifunctional, average molecular weight 1000) and TDI (Uniroy: NCO group concentration = (6.41 wt%) 5000 parts by weight are degassed in advance and adjusted to a temperature of 80 ° C. Etacure 300 (a mixture of 3,5-bis (methylthio) -2,4-toluenediamine and 3,5-bis (methylthio) -2,6-toluenediamine having a liquid temperature of 25 ° C. was added to this isocyanate group-terminated prepolymer. Albemar)) A mixture of 585 parts by weight and 123 parts by weight of Etacure 100 (Albemarle) which is diethyltoluenediamine (Etacure 300 / Etacure 100 = 80/20 (mol ratio)) is added and stirred to form a reactive composition And then poured into a mold preheated to 100 ° C. Thereafter, it was cured by heating in an oven at 100 ° C. for 1 hour, and then demolded, and further post-cured in an oven at 100 ° C. for 16 hours to prepare a run-flat tire support. The evaluation results of the obtained run-flat tire support are shown in Table 1.

(Comparative Example 1)
A run-flat tire support was produced in the same manner as in Example 1 except that 927 parts by weight of 4,4′-methylenebis (o-chloraniline) (MOCA: Ihara Chemical Co.) was used as a chain extender. The evaluation results of the obtained run-flat tire support are shown in Table 1.

(Comparative Example 2)
Ecure 300 (Albemarle) 439 parts by weight of diethyl and 3,5-bis (methylthio) -2,4-toluenediamine and 3,5-bis (methylthio) -2,6-toluenediamine as chain extenders A run flat tire support is prepared in the same manner as in Example 1 except that 247 parts by weight of Etacure 100 (Albemarle), which is toluenediamine, is used (Etacure 300 / Etacure 100 = 60/40 (mol ratio)). However, the reactive composition was cured before filling the entire mold, and the support could not be molded.

(Comparative Example 3)
A run flat tire support was produced by RIM molding. As a polyol component, a composition in which 5000 parts by weight of SBU polyol M300 (Sumika Bayer Urethane Co., Ltd.), 5 parts by weight of catalyst DABCO33LV (Air Product Co., Ltd.) and 5 parts by weight of dibutyltin dilaurate is used, and the liquid temperature is adjusted to 35 ° C. Air loading (40%) was performed. Use Sumijoule PF (Sumika Bayer Urethane Co., Ltd.) as the isocyanate component after adjusting the liquid temperature to 35 ° C., and use a RIM molding machine to collide the polyol component and the isocyanate component to 5010/2550 (weight ratio). A run-flat tire support was prepared by mixing to form a reactive composition and pouring it into a mold. The evaluation results of the obtained run-flat tire support are shown in Table 1.

[Evaluation methods]
(hardness)
The measurement was performed according to JIS K 7312. For the measurement, a durometer A hardness tester and a D hardness tester were used.

(Elastic modulus, modulus)
The measurement was performed according to JIS K 7312. A dumbbell No. 3 type was used as a test piece, and measurement was performed at an ambient temperature of 23 ° C. and a crosshead speed of 500 mm / min.
(Step impact test)
A run-flat tire support and a tire were attached to the rim to form a run-flat tire, which was filled with an air pressure of 240 kPa and attached to an actual vehicle. The vehicle was collided with a step having a height of 80 mm at a speed of 60 km / h, and the maximum deformation amount of the bead seat portion of the rim was measured. The case where the maximum deformation amount was less than 3 mm was evaluated as ◯, and the case where the maximum deformation amount was 3 mm or more was evaluated as x. The “maximum deformation amount of the bead seat portion of the rim” is the maximum value of the deformation amount that the rim receives through the support at the time of the above-described step collision, and the IN side (vehicle This is a value obtained by measuring the deformation on the inner side.

(Measurement of ground pressure)
A sheet-like pressure sensor was grounded at a place to be a ground contact surface, a run flat tire support was mounted on a predetermined rim, and a predetermined load was applied on the pressure sensor to measure the ground pressure.

(Durability test)
A run-flat tire support and a tire were attached to the rim to form a run-flat tire, which was attached as one wheel of an actual vehicle. The vehicle traveled at a speed of 100 km / h with the wheel air pressure set to zero, and the travelable time was measured. The case where it was able to run for 2 hours or more was evaluated as “◯”, and the case where the traveling time was less than 2 hours was evaluated as “x”.

  From the results of Table 1 above, the run-flat tire support of the present invention has a 10% elongation modulus, a small contact pressure, clears the step impact test, and the durability test, although the hardness is almost the same as the comparative example. Was also something to clear. On the other hand, a support made of polyurethane elastic body using MOCA disclosed in Patent Document 2 and a support made of RIM molded polyurethane elastic body as disclosed in Patent Document 1 are both step impact tests. The durability test could not be cleared.

The perspective view which illustrated the run flat tire support of the present invention Sectional drawing which illustrated the run-flat tire support body of this invention

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Run flat tire support body 12 Inner peripheral part 13 Inner peripheral surface 14 Outer peripheral part 16, 20 Rib part 22 Reinforcement cord layer

Claims (5)

A run-flat tire support made of an elastic body, comprising an outer peripheral part, an inner peripheral part having an inner peripheral surface in contact with the rim, and a rib part connecting the outer peripheral part and the inner peripheral part,
The elastic body is composed of an isocyanate prepolymer composed of polyether glycol and aromatic diisocyanate, 3,5-bis (methylthio) -2,4-toluenediamine, and 3,5-bis (methylthio) -2,6-toluenediamine. A run-flat tire support, which is a polyurethane elastic body obtained by reaction-curing at least one (bis (methylthio) toluenediamine) as a chain extender.   The run-flat tire support according to claim 1, further comprising diethyltoluenediamine as a chain extender so as to be 30 mol% or less in the total amount of the chain extender.   The run-flat tire support according to claim 1 or 2, wherein a reinforcing cord layer including a reinforcing cord is provided in the inner circumferential portion in the rim circumferential direction. The outer peripheral portion has an inner peripheral surface in contact with the rim, and includes an inner peripheral portion having a reinforcing cord layer including a reinforcing cord in the circumferential direction of the rim, and a rib portion connecting the outer peripheral portion and the inner peripheral portion. A method for producing a run-flat tire support formed of a body,
A reinforcing cord layer forming step for supplying a reinforcing cord to the outer periphery of the mold forming surface that forms the inner peripheral surface, and a reactive composition that forms a polyurethane elastic body is supplied to the molding cavity of the die to be reacted and cured. Having a curing step,
The reactive composition includes an isocyanate prepolymer composed of polyether glycol and aromatic diisocyanate, 3,5-bis (methylthio) -2,4-toluenediamine, 3,5-bis (methylthio) -2,6- A method for producing a run-flat tire support, comprising at least one toluenediamine (bis (methylthio) toluenediamine) mixed as a chain extender.   The method for producing a run-flat tire support according to claim 4, further comprising diethyltoluenediamine as a chain extender so as to be 30 mol% or less in the total amount of the chain extender.

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