JP2002137227A - Bladder for vulcanizing tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a bladder for vulcanizing a tire capable of assuring a desired inner liner gage even when a crude tire using a very thin unvulcanized rubber sheet member for the inner liner is vulcanization molded. SOLUTION: A plurality of oblique vent grooves 16 are circumferentially formed on an outer periphery of a bladder body 14 of the bladder 10 for vulcanizing the tire, and a net-like vent grooves 18 are formed between the grooves 16. Since a depth of each groove is set to 0.1 to 0.2 mm, even when the unvulcanized rubber sheet for the very thin inner liner is used for the inner surface of the crude tire due to an expansion of the bladder, a local flow of the rubber when pressure contacted with the tire is suppressed, and the gage of the liner when the product is produced can be assured.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vulcanizing bladder for a tire used when vulcanizing a pneumatic tire with a mold.

[0002]

2. Description of the Related Art In a tire vulcanizing apparatus for vulcanizing a pneumatic tire, an inflatable and contractible vulcanizing bladder made of an elastic material such as rubber is used.

[0003] The vulcanized bladder for a tire is disposed inside a green tire, and when inflated, presses against the inner surface of the green tire to support the raw tire from the inside and to adhere the outer surface of the raw tire to the inner surface of the mold. are doing.

When the vulcanized bladder for tires expands and comes into contact with the inner surface of the raw tire, an air trap (air trap) is formed between the vulcanized bladder for tires and the inner surface of the raw tire, which has an adverse effect upon vulcanization. Conventionally, the outer surface of the vulcanized bladder for tires has a depth of 0.3 to 1.0 mm on the outer peripheral surface of the vulcanized bladder for tires in order to allow air between the raw tire and the vulcanized bladder for tires to escape to the outside at the initial stage of vulcanization. A plurality of vent grooves are provided in the circumferential direction.

[0005]

By the way, in recent years, in order to reduce the weight of tires, it has been proposed to reduce the thickness of the inner liner of a tire using a rubber composition having excellent internal pressure retention and oxygen impermeability.

In this method, an unvulcanized rubber sheet member for an inner liner used in forming a green tire is used having a thickness of 0.2 to 0.8 mm, and the inner liner gauge of the product is set to 0.1 to 0.8 mm. It is about 0.4 mm.

However, when the unvulcanized rubber sheet member is thinned, the rubber flows near the edge of the air escape groove when the vulcanizing bladder is pressed, and the inner liner gauge is locally thinned, and the internal pressure holding property is reduced. In addition, there was a problem that the inner liner gauge required for oxygen impermeability could not be secured.

[0008] In view of the above facts, the present invention provides a tire capable of securing a desired inner liner gauge even when vulcanizing a green tire using a very thin unvulcanized rubber sheet member for an inner liner. It is an object to provide a vulcanized bladder for use.

[0009]

According to the present invention, there is provided a vulcanizable bladder for tires which is formed of an elastic material and which supports the tire from the inside during vulcanization of the tire. A mesh vent groove is formed at least in the outer peripheral surface area of the bladder facing the area from the 1/8 position of the tire tread to the bead when the tire is in intimate contact with the inner surface of the tire. 1-0.2m
m is set.

Next, the operation of the vulcanized bladder for a tire according to the first aspect will be described.

In the vulcanized bladder for a tire according to the first aspect, a mesh-shaped vent groove is formed on an outer peripheral surface of the vulcanized bladder for a tire, which is in contact with an inner surface of the vulcanized tire. When in contact with the inner surface of the tire, the air between the vulcanized bladder for tires and the green tire escapes to the outside through the mesh vent groove, so that the vulcanized bladder for tires supports the tire from the inner surface without generating unnecessary air pockets can do.

Here, since the depth of the mesh vent groove of the vulcanizing bladder for tires is set to 0.1 to 0.2 mm,
When the gauge of the unvulcanized rubber sheet member for the inner liner of the green tire is extremely thin (for example, 0.2 to 0.8 m
Even in the case of m), an inner liner gauge required as a product tire can be ensured in a portion crimped on the mesh vent groove and in the vicinity thereof.

The mesh vent groove has a groove depth of 0.1 m.
If it is less than m, there is a possibility that the air between the tire and the inner surface cannot be reliably released.

Further, the depth of the mesh vent groove is 0.2 m.
If it exceeds m, when the gauge of the unvulcanized rubber sheet member is thin (for example, 0.2 to 0.8 mm), the inner liner gauge required for a product tire may not be able to be secured.

According to a second aspect of the present invention, there is provided the vulcanized bladder for a tire according to the first aspect, wherein the mesh-shaped vent groove is provided on the entire surface of the portion facing the inner surface of the tire when expanded and in close contact with the inner surface of the tire. It is characterized by being formed.

Next, the operation of the vulcanized bladder for a tire according to the second aspect will be described.

Since the mesh-shaped vent groove is formed on the entire surface facing the tire inner surface when the vulcanized bladder for a tire is inflated and closely attached to the tire inner surface, air accumulation can be reliably prevented on the entire tire inner surface portion.

The vulcanized bladder for rubber tires is
In general, since a mold is formed by a split mold, a streak remains in a portion in close contact with a joint between the molds.

It is preferable to form a mesh vent groove avoiding the streaks remaining on the surface of the vulcanized bladder for a tire. The reason is that when trimming the burrs (rubber) protruding from the mold seam, it is difficult to process the concave and convex portions, so that a large number of work steps are required.

According to a third aspect of the present invention, there is provided the vulcanizing bladder for a tire according to the first or second aspect, wherein the outer peripheral surface is provided along a direction inclined with respect to a direction corresponding to a radial direction of the tire. A plurality of extending inclined vent grooves are formed at intervals in a direction corresponding to the circumferential direction of the tire.

Next, the operation of the vulcanized bladder for a tire according to the third aspect will be described.

In the tire vulcanizing bladder according to the third aspect, air can be released between the tire and the inner surface even through the inclined vent groove.

According to a fourth aspect of the present invention, there is provided the vulcanizing bladder for a tire according to the third aspect, wherein the inclined vent groove is formed on the entire surface of the portion facing the inner surface of the tire when expanded and in close contact with the inner surface of the tire. It is characterized by being.

Next, the operation of the vulcanized bladder for a tire according to claim 4 will be described.

In the tire vulcanizing bladder according to the fourth aspect, the air between the tire and the inner surface can be released even through the inclined vent groove.

According to a fifth aspect of the present invention, there is provided a vulcanizable bladder for a tire which is formed of an elastic material and which supports the tire from the inside during vulcanization of the tire. In the bladder outer peripheral surface region facing at least the region from the 1/8 position of the tire tread to the bead portion, an inclined vent groove extending along a direction inclined with respect to the radial direction of the tire is formed in the circumferential direction of the tire. Are formed at intervals in the direction corresponding to.

Next, the operation of the vulcanized bladder for a tire according to claim 5 will be described.

In the tire vulcanizing bladder according to the fifth aspect, since a plurality of inclined vent grooves are formed on the outer peripheral surface in contact with the tire inner surface to be vulcanized, the tire vulcanizing bladder expands. When in contact with the inner surface of the raw tire, the air between the vulcanized bladder for the tire and the raw tire escapes to the outside through a plurality of inclined vent grooves, so that the vulcanized bladder for the tire removes the tire without generating unnecessary air pockets. It can be supported from the inner surface.

Here, since the groove depth of the inclined vent groove of the vulcanized bladder for tires is set to 0.1 to 0.2 mm, when the gauge of the unvulcanized rubber sheet member for the inner liner of the green tire is thin. (For example, 0.2 to 0.8 mm), the inner liner gauge required as a product tire can be ensured even in a portion crimped to the inclined vent groove and in the vicinity thereof.

The depth of the inclined vent groove is 0.1 mm.
If it is less than the above, there is a possibility that air between the inner surface of the tire and the tire cannot be reliably released.

The depth of the inclined vent groove is 0.2 mm.
When the value exceeds, when the gauge of the unvulcanized rubber sheet member is thin (for example, 0.2 to 0.8 mm), the inner liner gauge required for the product tire may not be able to be secured.

According to a sixth aspect of the present invention, in the vulcanizing bladder for a tire according to the fifth aspect, the inclined vent groove is provided on the entire surface of the portion facing the inner surface of the tire when expanded and in close contact with the inner surface of the tire. It is characterized by being formed.

Next, the operation of the vulcanized bladder for a tire according to claim 6 will be described.

Since the inclined vent groove is formed on the entire surface facing the inner surface of the tire when the vulcanized bladder for tires expands and comes into close contact with the inner surface of the tire, air accumulation can be reliably prevented on the entire inner surface of the tire.

The vulcanized bladder for rubber tires is
In general, since a mold is formed by a split mold, a streak remains in a portion in close contact with a joint between the molds.

It is preferable to form an inclined vent groove so as to avoid streaks remaining on the surface of the vulcanized bladder for a tire. The reason is that the burrs (rubber) protruding from the mold seam
This is because, when trimming, it is difficult to process the concave and convex portions, so that a large number of work steps are required.

[0037]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of a vulcanized bladder for a tire according to the present invention will be described with reference to FIGS.

FIG. 1 shows a vulcanizing bladder 10 for a tire in a free state. The vulcanizing bladder 10 for a tire of the present embodiment is a so-called open-end type bladder having a ring shape.

The vulcanizing bladder 10 for a tire is provided with flange portions 12 each having an opening that opens in the axial direction at both ends in the axial direction (the direction of arrow A in FIG. 1).

An inflatable tubular bladder body 14 is integrally extended between the one flange portion 12 and the other flange portion 12. This vulcanized bladder for tires 1
As the material of 0, for example, butyl rubber or the like can be used.

As shown in FIG. 2, on the outer peripheral surface of the bladder body 14, inclined vent grooves 16 (only a part is shown in FIG. 2) extending at an angle to the axial direction are provided at regular intervals in the circumferential direction. While being formed, between the inclined vent groove 16 and between the inclined vent groove 16, a mesh-shaped vent groove 18 having a random mesh shape (also called pebble processing, a large number of pebbles are gathered) There is a groove between the pebbles, and only a part is shown in FIG. 2).
Are connected to each other.

Here, the groove depth of the inclined vent groove 16 and the groove depth of the mesh vent groove 18 are each 0.1 to 0.2 mm.
When the inclined vent groove 16 and the mesh vent groove 18 are used together as in the present embodiment, it is preferable to set the maximum value of the irregularities on the outer peripheral surface to 0.3 mm or less.

The depth of the inclined vent groove 16 and the depth of the mesh vent groove 18 may be the same or different.

On the outer peripheral surface of the vulcanizing bladder 10 for tires, the area where the inclined vent groove 16 and the mesh vent groove 18 are formed expands as shown in FIG. At least 1/8 position 26 of the tire tread 24 (at a distance of 1/8 of the tread width TW from the tread end to the tire equatorial plane CL) from the tire tread 24 to the bead portion (bead toe) 28 It is preferable to form it at the position where it is.

When the inclined vent groove 16 and the mesh vent groove 18 are inflated and brought into close contact with the inner surface of the raw tire 22,
It may be formed on the entire surface facing the inner surface of the tire. In this case, it is preferable to form the inclined vent groove 16 and the mesh vent groove 18 so as to avoid streaks due to the joint of the mold remaining on the surface of the vulcanizing bladder 10 for a tire. (Operation) Next, the operation of the vulcanized bladder 10 for a tire according to the present embodiment will be described.

The vulcanizing bladder 10 for a tire is used in a vulcanizing machine as before.

When the green tire is set in the vulcanizing mold 20 of the vulcanizer and air (or steam) is introduced into the vulcanizing bladder 10 for a tire, as shown in FIG. The bladder body 14 is inflated and pressed against the inner surface of the raw tire 22, and the raw tire 22 is pressed against the inner surface of the vulcanization mold 20.

Here, when the vulcanized bladder for tires 10 expands and comes into contact with the inner surface of the raw tire 22, the air between the vulcanized bladder for tires 10 and the inner surface of the raw tire 22 becomes:
It is discharged to the outside through the inclined vent groove 16 and the mesh vent groove 18.

Here, the air near the inclined vent groove 16 flows outward to the inclined vent groove 16 side,
The air between the air gap and the inclined vent groove 16 is a mesh vent groove 18.
To the outside or to the inclined vent groove 16 to prevent the occurrence of air accumulation.

Thereafter, the outer surface of the vulcanized bladder 10 for a tire is completely adhered to the inner surface of the green tire 22.

It is to be noted that the portion of the tire inner surface after vulcanization pressed against the inclined vent groove 16 and the mesh vent groove 18 of the vulcanizing bladder 10 for a tire has a conventional shape.

Here, a thin inner liner is provided on the inner surface of the tire, but if there is a concave portion on the outer peripheral surface of the vulcanized bladder for a tire, the vulcanized bladder for the tire is pressed against the inner liner of the raw tire. When doing, local flow occurs in the raw rubber that abuts the recess, not only can not obtain the thickness of the inner liner necessary for internal pressure holding,
The arrangement of carcass cords adjacent to the inner liner may be disordered (so-called cord suction phenomenon),
Conventionally, the gauge of the inner liner is set to be thick to prevent the internal pressure from being held and the carcass cord from being disturbed.

However, in the vulcanizing bladder 10 for a tire according to the present embodiment, the depths of the inclined vent grooves 16 and the mesh vent grooves 18 which are the concave portions are each 0.1 to 0.2 m.
m, since the unevenness of the outer peripheral surface is set to 0.3 mm or less, the unvulcanized rubber sheet for the inner liner of the raw tire 22 is extremely thin, for example, 0.2 to 0.8 mm (see FIG. 3). (Not shown), the local flow of rubber at the time of pressing against the raw tire 22 is suppressed, and the gauge of the inner liner at the time of the product can be secured.

Further, in the product tire, the protruding portion on the inner surface of the tire, which is the mark of the inclined vent groove 16 and the mesh vent groove 18, is kept low in height, so that there is no possibility that the protruding portion cracks. .

Incidentally, with the expansion of the bladder body 14,
The bladder body 14 is extended in the plane direction, and the groove depth of the inclined vent groove 16 and the groove depth of the mesh vent groove 18 are reduced.

Further, since the bladder body 14 has a different amount of tension depending on the portion, the groove depth when inflated may be partially different.

Therefore, it is not necessary to make the groove depth of the inclined vent groove 16 and the mesh vent groove 18 constant over the entire bladder main body 14, and the groove depth may be appropriately changed depending on the portion.

For example, when the contact of the inner surface of the tire starts from the equator portion of the bladder body 14, the groove depth should be increased from the tire equatorial surface CL toward the portion corresponding to the bead portion 28. It is preferable in terms of efficiency.

Further, in consideration of the stress at the time of expansion, it is preferable that each groove edge portion of the inclined vent groove 16 and the mesh vent groove 18 has a chamfered shape as smooth as possible.

If the depth of the inclined vent groove 16 and the mesh vent groove 18 is less than 0.1 mm, the flow of air deteriorates.
It is not preferable to use an unvulcanized rubber sheet for the inner liner which is very thin, such as 0.8 mm, as compared with the conventional one, because the inner liner gauge of the product tire becomes too thin.

The number of the inclined vent grooves 16 is 4 to 25 per 10 cm, preferably 8 to 20 per 10 cm, at least in a portion corresponding to the shoulder portion (tread edge) of the raw tire 22. Vent groove 1
6 has a groove width (when not expanded) of 0.5 to 2.0 mm, preferably 0.5 to 1.5 mm.

Here, if the number of the inclined vent grooves 16 is less than the above range, air is easily accumulated, which is not preferable. On the other hand, if the number of the inclined vent grooves 16 is larger than the above range, the raw tire 22 and the vulcanized bladder
This is not preferred because the slippage of the tire becomes worse and the deterioration of the vulcanized bladder 10 for tires is accelerated.

Next, the negative rate in the region where the mesh vent groove 18 is arranged is 20 to 80%, preferably 30 to 60%, and the groove width of the mesh vent groove 18 (when not inflated) is 0.5 to 2.0 mm, preferably 0.5 to
1.5 mm.

Here, if the negative rate in the area where the mesh vent groove 18 is arranged is smaller than the above range, air accumulation tends to occur, which is not preferable. On the other hand, if the negative rate in the region where the mesh vent groove 18 is arranged is larger than the above range, the slip between the raw tire 22 and the vulcanized bladder 10 for tires becomes poor, and the vulcanized bladder 1 for tire 1
It is not preferable because the deterioration of 0 is accelerated.

In the above embodiment, the present invention has been described by taking an example of an open-end bladder. However, the present invention is not limited to this, and the present invention can be applied to other types of bladders, such as a closed-end bladder having one open end. Of course, the invention may be applied.

Here, as the rubber composition for the inner liner, (A) a rubber component containing 25 to 100% by weight of a halogenated butyl rubber and 0% to less than 20% by weight of a diene rubber; Those containing a layered or plate-like inorganic filler having a ratio of 5 or more and less than 30 can be used.

If the content of the halogenated butyl rubber in the rubber component is less than 25% by weight, sufficient air permeation resistance cannot be exhibited.

In consideration of air permeation resistance, the content of the halogenated butyl rubber is preferably at least 50% by weight, particularly preferably at least 70% by weight.

The content of the diene rubber is 20% by weight.
Above, the air permeation resistance decreases. Considering air permeability resistance and flex fatigue resistance, halogenated butyl rubber 4
It is advantageous to use a rubber component composed of 85 to 100% by weight of butyl rubber containing 0% by weight or more and 15 to 0% by weight of diene rubber.

The halogenated butyl rubber includes chlorinated butyl rubber, brominated butyl rubber, modified rubber thereof, and the like. For example, as chlorinated butyl rubber, "Enja
There is "YButyl HT10-66" (trademark, manufactured by Enge Chemical Co., Ltd.), and as a brominated butyl rubber, "bromobutyl 2255" (trademark, manufactured by Exxon Corporation).

As the modified rubber, a chlorinated or brominated modified copolymer of a copolymer of isomonoolefin and paramethylstyrene can be used.
50 "(manufactured by Exxon, trademark).

Examples of the diene rubber which can be compounded in the rubber component include, for example, natural rubber, isoprene synthetic rubber (IR), cis 1,4-polybutadiene (BR), syndiotactic-1,2-polybutadiene ( 1,2B
R), styrene-butadiene rubber (SBR), acrylonitrile-butadiene rubber (NBR), chloroprene rubber (CR), and the like. These may be used alone or in combination of two or more.

In the rubber composition for the inner liner, the component (B) has an aspect ratio of 5 to 30.
Less than layered or plate-like inorganic fillers are used.

Here, the aspect ratio means that the inorganic filler is observed with an electron microscope, and the major axis and minor axis of 50 arbitrary particles are measured (FIG. 4 shows the major axis and minor axis of the unit particle). It is determined as a / b from the average major axis a and the average minor axis b.

When the layered or plate-like inorganic filler having the above aspect ratio is blended with the rubber component as the component (A), the layered structure is formed in the extrusion or pressing step, and the air permeation path is formed. The shielding and air permeability are effectively exhibited.

Therefore, the air permeation resistance can be improved with a smaller amount than ordinary carbon black or inorganic filler.

As a result, an increase in hardness at low temperatures can be suppressed as compared with conventional carbon black and inorganic fillers, so that durability at low temperatures can be improved.

If the aspect ratio is less than 5, the effect of improving the air permeability may not be sufficiently exhibited.
Above, the dispersion of the rubber component becomes worse, the layer effect becomes weaker,
Rather, the air permeability tends to be poor.

Further, when the aspect ratio is 30 or more, the dispersion of the filler becomes poor, and a kneading stage must be added until the kneading conditions are dispersed, thereby deteriorating the productivity. From this viewpoint, a more preferable aspect ratio is in the range of 10 to 20.

The layered or plate-like inorganic filler having such an aspect ratio may be any of natural products and synthetic products, and is not particularly limited. Examples thereof include kaolin, clay, mica, feldspar, silica and alumina. And a water-containing complex.

Among these, kaolin clay and sericite clay are preferred.

Further, in this layered or plate-like inorganic filler, if the average particle size is too large, the bending fatigue resistance may be reduced. Therefore, the average particle size is preferably 30 μm or less.

As the layered or plate-like inorganic filler of the component (B), one kind may be used alone, or two or more kinds may be used in combination.

The content is preferably in the range of 10 to 270 parts by weight per 100 parts by weight of the rubber component (A).

If the content of the component (B) is less than 10 parts by weight, the effect of blending the component (B) may not be sufficiently exerted. If the content exceeds 270 parts by weight, the hardness increases and the low temperature resistance Cracking properties are deteriorated and bending fatigue resistance is reduced.

From this viewpoint, the more preferable content of the component (B) is in the range of 20 to 180 parts by weight.

In the rubber composition, for the purpose of improving the strength of the unvulcanized rubber, the component (A) 100
(C) carbon black 0 to 80 per part by weight
Parts by weight, preferably 10 to 60 parts by weight.

When the content of the component (C) exceeds 80 parts by weight, the hardness increases, and the low-temperature crack resistance and the bending fatigue resistance tend to decrease.

The type of the carbon black of the component (C) is not particularly limited, and any type can be appropriately selected from those conventionally used as a reinforcing filler for rubber, and examples thereof include FEF, SRF, HAF, ISA
F, SAF, GPF and the like.

Among these, the dibutyl phthalate oil absorption (DBP) is 65 ml / 100 g or more, preferably 65 to 100 ml / 100 g, and the iodine adsorption amount (IA) is 20 mg / g or more, preferably 20 to 100 mg / g. Those in the range of 38 mg / g are desirable.

The total content of the component (B) and the component (C) is determined based on the balance between the air permeability resistance, bending fatigue resistance, low-temperature crack resistance, and workability.
The range of 30 to 300 parts by weight per part by weight is preferable,
Particularly, the range of 50 to 250 parts by weight is suitable.

In this rubber composition, for the purpose of improving the dispersibility of the lamellar or plate-like inorganic filler and carbon cracks in the rubber component and improving the desired physical properties, the rubber composition contains 100 parts by weight of component (A). Further, (D) 0 to 5 parts by weight of a dispersion improver can be contained. Examples of the dispersion improver include a silane coupling agent, dimethylstearylamine, and triethanolamine. These may be used alone or in a combination of two or more.

Further, in the rubber composition, when the above-mentioned carbon black is blended, the naphthenic oil or the paraffin oil is added in an amount of not less than 1 part by weight per 100 parts by weight of the rubber component (A). In particular, it is preferable to contain 3 to 20 parts by weight.

[0094] Here, naphthenic oil preferably has% C _N by ring analysis of 30 or more, paraffinic oil% C _P is preferably of 60 or more.

Such a rubber composition has a vulcanized rubber having a 0.1% dynamic elastic modulus at −20 ° C. of usually 800 MPa.
a or less, preferably 600 MPa or less.

The rubber composition may optionally contain
Organic short fibers can be included.

When this organic short fiber is contained, the inner cord exposure which occurs when the inner liner is formed into a gauge and a tire is manufactured can be suppressed.

The organic short fibers have an average diameter of 1 to 100 μm.
Preferably, the average length is about 0.1 to 0.5 mm.

This organic short fiber may be blended as FRR (composite of short fiber and unvulcanized rubber).

The content of such organic short fibers is as follows:
0.3 to 15 parts by weight per 100 parts by weight of the component is preferred.

If the amount is less than 0.3 part by weight, the effect of eliminating the inner cord exposure is small, and if it exceeds 15 parts by weight, workability may be adversely affected.

The material of the organic short fiber is not particularly limited, and examples thereof include polyamides such as nylon 6 and nylon 66, syndiotactic-1,2-polybutadiene, isotactic polypropylene, and polyethylene. Among them, polyamide is preferable.

In order to increase the modulus of the rubber compounded with organic short fibers, an adhesion improver between the rubber and the fiber, such as hexamethylenetetramine or resorcinol, can be further compounded.

The rubber composition may contain various chemicals usually used in the rubber industry, such as a vulcanizing agent, a vulcanization accelerator, an antiaging agent, in addition to the above-mentioned compounding agents, as long as the object of the present invention is not impaired. , An anti-scorch agent, zinc white, stearic acid, and the like.

The rubber composition thus obtained is used as a rubber composition for an inner liner.

The raw tire 22 can be manufactured by a usual method using the rubber composition.

That is, if necessary, the rubber composition containing various chemicals as described above is subjected to extrusion calendering as an inner liner member at an unvulcanized stage, and the inner liner is thinned by a conventional production method. A gauged tire can be easily manufactured. (Test Example) In order to confirm the effect of the present invention, a tire vulcanizing bladder of a conventional example, a tire vulcanizing bladder of a comparative example and a tire vulcanizing bladder of an example to which the present invention was applied were used. A vulcanization test was performed.

The raw tire used in the test had a size of 205 / 65R15 when manufactured, and the gauge of the uncured sheet rubber composition for the inner liner of the control tire (current tire) was 1.0 mm. And the gauge of the tire is 0.4 mm.

The composition of the unvulcanized rubber composition for the inner liner used for the control tire, and the composition of the unvulcanized rubber composition for the inner liner used for the tires of Examples and Comparative Examples were as follows. It is as described in Table 1 below.

[0110]

[Table 1]

In the tire vulcanizing bladder, the inclined vent grooves are 120 on the right and left sides of the equator plane (central part in the axial direction) on the right and left sides, and are inclined by 20 ° with respect to the axial direction.
The groove width when not expanded is 0.8 mm.

On the other hand, the negative ratio (groove area per unit area) of the portion where the mesh vent groove is formed is 40%, and the groove width of the mesh vent groove when the vulcanizing bladder for tire is not inflated. Is 0.8 mm on average.

In the vulcanized product tire, the presence or absence of an air trap, the minimum gauge of the inner liner near the shoulder, and the internal pressure retention were examined.

The internal pressure retention was measured by assembling a tire with a rim, filling a predetermined initial internal pressure, and measuring the internal pressure after a lapse of a predetermined period.
The reciprocal of the rate of decrease in the internal pressure of the control product was expressed as an index with 100 being the reciprocal. The results are as shown in Table 2 below, and the larger the numerical value, the lower the internal pressure is and the more excellent the internal pressure is.

The quarter position in the table is a position separated from the tread edge by a quarter of the tread width to the tire equatorial plane.

[0116]

[Table 2]

The tire according to the embodiment to which the present invention is applied uses the unvulcanized sheet rubber composition for the inner liner, which is thinner than the current product, so that the tire is reduced in weight and, moreover, the air pool is formed. No internal pressure retention was found, and the internal pressure retention was higher than that of the current control product.

[0118]

As described above, the vulcanized bladder for a tire according to the present invention has the above-described structure, and is used for vulcanizing a raw tire using a thin sheet-shaped unvulcanized inner liner member. This also has an excellent effect that a desired inner liner gauge can be secured.

[Brief description of the drawings]

FIG. 1 is a side view of a cross-section of a part of a tire vulcanizing bladder according to an embodiment of the present invention.

FIG. 2 is an enlarged view of a bladder surface.

FIG. 3 is a schematic view showing an internal structure of a vulcanizer provided with a vulcanizing bladder for a tire of the present embodiment.

FIG. 4 is an explanatory diagram illustrating an aspect ratio.

[Explanation of symbols]

 Reference Signs List 10 Vulcanized bladder for tire 16 Inclined vent groove 18 Reticulated vent groove

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4F202 AH20 AM32 CA21 CT01 CU07 CU12 CV13 CV21 4F203 AH20 AM32 DA11 DB01 DC01 DK07 DL12 DL14 DM04

Claims (6)

[Claims] An inflatable vulcanizing bladder for a tire, which is formed of an elastic material and supports the tire from the inside during vulcanization of the tire, wherein at least one-third of the tire tread when inflated and closely attached to the tire inner surface. A mesh vent groove is formed in the outer peripheral surface region of the bladder facing the region from the 8 position to the bead portion, and the groove depth of the mesh vent groove is 0.1 to 0.2 mm.
Vulcanized bladder for tires, characterized in that: 2. The vulcanizing bladder for a tire according to claim 1, wherein the mesh-shaped vent groove is formed on the entire surface of the portion opposed to the tire inner surface when inflated and closely attached to the tire inner surface. . 3. A plurality of inclined vent grooves extending along a direction inclined with respect to a radial direction of a tire are formed on an outer peripheral surface at intervals in a direction corresponding to a circumferential direction of the tire. The vulcanized bladder for tires according to claim 1 or 2, wherein 4. The vulcanizing bladder for a tire according to claim 3, wherein the inclined vent groove is formed on an entire surface facing a tire inner surface when the tire is inflated and closely attached to the tire inner surface. 5. An inflatable vulcanizing bladder for a tire, which is formed of an elastic material and supports the tire from the inside during vulcanization of the tire, wherein at least one-third of the tire tread when inflated and closely attached to the tire inner surface. In the bladder outer peripheral surface region facing the region from the 8 position to the bead portion, an inclined vent groove extending along a direction inclined with respect to a direction corresponding to the radial direction of the tire is provided with an interval in a direction corresponding to the circumferential direction of the tire. A vulcanized bladder for tires that is formed by opening a plurality. 6. The vulcanizing bladder for a tire according to claim 5, wherein the inclined vent groove is formed on the entire surface of the portion facing the inner surface of the tire when inflated and closely attached to the inner surface of the tire.