JP2002087015A - Bead core-containing foamed tire and method for producing the same - Google Patents

Abstract

(57) [Summary] [Problem] A bead core-containing foamed tire having sufficient ride comfort while maintaining various performances relating to durability such as sufficient tire rigidity, rim slip resistance, and abrasion resistance. Get. SOLUTION: At least the tread side and the side side of a foamed layer 2 having an expansion ratio of 1.5 to 2.5 are covered with a non-foamed surface layer 4, and the thickness of the side surface layer 4 with respect to the tire width. 2
The thickness of the surface layer 4 on the tread side is set to 5 to 15% with respect to the tire height. JIS-K62 of surface layer 4
53: Type A durometer hardness test A45 to hardness
65 degrees, JIS-K7312 of foam layer 2: Hardness was set to 40 to 70 degrees HsC by type C hardness test, and surface layer 4
The tensile stress at the time of 100% elongation is 1.5 to 3.5 MPa.
The surface layer 4 and the foam layer 2 were formed of diene rubber, and a plurality of bead cores 6 were arranged at symmetrical positions with respect to the tire equatorial plane.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tire for use in an electric wheelchair for nursing care, a wheelchair for nursing care (manually), an electric carrier, a senior car used by elderly people with weak legs and waists, and the like. The present invention relates to a solid-type bead core-containing foamed tire that does not allow air to enter and a method for producing the same.

[0002]

2. Description of the Related Art Conventionally, tires used for wheelchairs, electric carriers, etc. have foam rubber at the center and are covered with solid rubber at the center as disclosed in JP-A-2-48201. Things are known. Thereby, moderate elasticity can be obtained even though the tire is a flat tire.

[0003]

Such a conventional device is used particularly for an electric wheelchair for nursing care, a wheelchair for nursing (manual), a senior car (electric carrier) used by elderly people with weak legs and waists, and the like. Ride comfort is important. However, at the same time, durability is also required, and abrasion resistance is required along with cost performance, and rim shift resistance and rigidity are also required in which rubber comes into contact with the rim flange during running. In addition, since the performance of these types of electric carriers has recently been improved, the load on the tires during running and the like has also increased. For these reasons, tires are required to have sufficient rigidity and the like. However, if the durability is excessively improved, the elasticity (cushioning property) is lost, and the most important problem is that the ride quality deteriorates. .

An object of the present invention is to provide an electric wheelchair for nursing care while maintaining various performances relating to durability such as sufficient tire rigidity, rim slip resistance, and abrasion resistance, and having a necessary and sufficient riding comfort. It is an object of the present invention to provide a bead core-containing foamed tire used for the like and a method for producing the same.

[0005]

Means for Solving the Problems In order to achieve the object, the present invention takes the following means to solve the problem. That is, at least the tread side and the side of the foamed layer having an expansion ratio of 1.5 to 2.5 are covered with a non-foamed surface layer, and the thickness of the surface layer on the side is 2 to 8% with respect to the tire width. The thickness of the surface layer on the tread side is 5 to the tire height.
15%, and JIS-K625 of the surface layer
3: The hardness was A45 to 6 in a type A durometer hardness test.
5 degree, JIS-K7312 of the foam layer: The hardness is set to 40 to 70 degrees HsC in a type C hardness test, and the tensile stress at the time of 100% elongation of the surface layer is 1.5 to 3.5 MP.
a, wherein the surface layer and the foamed layer are formed of diene rubber, and a plurality of bead cores are arranged at symmetrical positions with respect to the tire equatorial plane.

It is preferable that the inner peripheral length of the bead core is 1.01 to 1.05 times the outer peripheral length of the rim. Alternatively, the total width of the bead core is 10 to the rim width.
It may be up to 20%. Further, the bead core may be formed by being covered with a covering member. It is preferable that the bead core is arranged at least 1 mm inward from the side surface. The bead core may be provided in the surface layer on the side. Further, the base side in contact with the rim is covered with a non-foamed base rubber layer, and the height of the base rubber layer with respect to the total height of the tire is 10 to 30.
%, JIS-K6253 of the base rubber layer: Type A
The hardness may be A40 to 100 degrees in a durometer hardness test.

[0007] The tightening allowance when mounting the rim is 0 to 15% in the axial bead allowance and 0 to 5 in the radial bead large diameter allowance.
% And the bead small diameter interference allowance may be 5 to 15%. Alternatively, the surface layer may contain 1 to 3 PHR of waxes. Further, the surface layer is made of natural rubber and SB.
R and 13: 1 to 2: 1 by weight, and the styrene content in the SBR is 5 to 15% by weight.
Furthermore, white carbon is blended at 1 to 10 PHR, and carbon black of FEF class is 20 to 40 PHR.
15 ~ 35PH carbon black of R and HAF class
What was compounded with R and molded may be used. The foam layer contains natural rubber and SBR at a weight ratio of 7: 3 to 3: 7, and HAF class carbon black of 20 to 50P.
What was compounded with HR and molded may be used.

[0008] The unvulcanized rubber sheet for the foam layer is wound, bead cores are attached to both sides thereof, and the unvulcanized rubber for the surface layer is covered thereover, and the vulcanized rubber is put into a mold and vulcanized. That is the method for producing a bead core-containing foamed tire. Alternatively, the unvulcanized rubber for the foam layer and the unvulcanized rubber for the surface layer covering at least the tread side and the side side of the unvulcanized rubber for the foam layer are extruded into a rod shape by a double extruder, and the rod shape is formed. This is a method for producing a foamed tire containing a bead core, wherein the molded product is rolled into a ring shape, and a bead core is inserted into the inside of both sides of the unvulcanized rubber for the side surface layer and vulcanized.

[0009]

Embodiments of the present invention will be described below in detail with reference to the drawings. As shown in FIG. 1, reference numeral 1 denotes a foamed tire containing a bead core, and an expansion ratio of 1.5 to 2.
It has a five-fold foam layer 2 and a surface layer 4 that covers the foam layer 2. The surface layer 4 is provided so as to cover at least the tread side and the side sides of the foam layer 2. In addition, as shown in FIG. 3, the surface layer 4 may be provided on the rim side.

The foam layer 2 has the greatest influence on the cushioning performance, and since this part occupies most of the volume of the tire, it substantially affects the weight. When the expansion ratio of the foam layer 2 is 1.5 or less, the cushioning property is lacking,
The impact at the time of climbing over the convex portion becomes too large, and the riding comfort is lowered, which is not preferable as a nursing electric wheelchair or the like. When the expansion ratio exceeds 2.5 times, various rigidities (longitudinal rigidity and lateral rigidity) of the tire decrease,
Various performances related to durability, such as rim shift resistance and uneven wear resistance, may deteriorate, which is not preferable. Further, it is not preferable to stop the apparatus for a long time because the contact surface is set flat and a flat spot that rattles and vibrates at the start of traveling is likely to be generated.

The surface layer 4 is a non-foamed rubber compound having excellent durability such as abrasion resistance and crack resistance and also excellent rolling resistance. The thickness of the surface layer 4 is 2 to 8% on the side side (one side thickness T) with respect to the tire width W (=
T / W × 100), and is formed to be 5 to 15% of the tire height H on the tread side. The tread layer of the surface layer 4 is a place where the tire is directly worn, and when foamed, the abrasion resistance and the like are inferior and cannot be put to practical use.

If the thickness on the tread side is less than 5%, the durability tends to decrease during wear, which is not preferable. If it is larger than 15%, the ride comfort is likely to deteriorate, which is not preferable. If the thickness on the side is smaller than 2%, it is not preferable because durability is easily reduced at the time of trauma or rim misalignment.
If it is more than 8%, the cushioning property in the vertical direction of the tire is reduced, and the ride comfort is likely to be reduced, which is not preferable.

The surface layer 4 is made of JIS-K6253:
In a type A durometer hardness test, the hardness is A45 to 65 degrees, and the tensile stress at 100% elongation is 1.5 to 3.5.
MPa. If the hardness is less than 45 degrees, it tends to be too soft and the stability tends to be poor, and the rim deviation tends to increase, which is not preferable. If it exceeds 65 degrees, it is too hard and lacks cushioning properties, and the The impact becomes too large, which is not preferable as an electric wheelchair for nursing care or the like.

The tensile stress at the time of 100% elongation of the surface layer 4 is preferably 1.5 to 3.5 MPa, and if it is 1.5 MPa or less, it tends to be too soft and the stability tends to be poor. It is not preferable because cushioning tends to be lacking. On the other hand, if the tensile stress at the time of 100% elongation is 3.5 MPa or more, scratches, cracks, and the like generated during running are more likely to grow, which is not preferable. .

Further, the hardness of the foamed layer 2 is 40 to 70 degrees HsC in JIS-K7312: Type C hardness test. 40
If it is less than the degree, it is not preferable because it tends to be too flexible and the stability tends to be deteriorated, and if it exceeds 70 degree, it is too hard and lacks cushioning property, and the impact at the time of climbing over the convex part becomes too large, which is preferable as an electric wheelchair for nursing Absent.

The rubber component of the surface layer 4 and the foam layer 2 is a diene rubber. The surface layer 4 and the foam layer 2 are continuously and integrally molded in an unvulcanized state, and are vulcanized and joined. For example, in a conventional type in which urethane foam is injected into a pneumatic tire, the adhesive interface between the two may decrease in adhesive strength during long-term use and peel off. In addition, when moisture enters the inside, urethane is easily hydrolyzed and may be peeled off at the adhesive surface between the urethane foam and the tire.

Since the surface layer 4 and the foam layer 2 are simultaneously vulcanized and integrally bonded, they adhere well. In addition, since a diene rubber such as natural rubber, SBR, or BR is used, durability such as abrasion resistance is excellent. Furthermore, natural rubber, S
Diene-based rubbers such as BR and BR are excellent in sheeting (band-like rubber) when a tire is produced by multi-layer winding,
Sheeting can be easily performed (it is easy to adjust the thickness and width to any values), and since the sheet rubber is excellent in adhesiveness, molding is easy. The non-foamed portion of the surface layer 4 is adhered and molded so as to cover the multilayered foamed layer 2, but the adhesiveness of both is excellent, so that the moldability is good.

In the foamed tire 1 with a bead core, a plurality of bead cores 6 are arranged symmetrically with respect to the tire equatorial plane. In the present embodiment, two bead cores 6 are arranged at symmetrical positions with respect to the tire equatorial plane. The bead core 6 includes a so-called bundled strand wire formed by winding a number of bead wires, and a bead core 6 made of a single thick ring. It is more preferable that the bead core 6 be plated with brass or adhered to a surrounding rubber portion using a general vulcanizing adhesive or the like.

When a split rim is used as the rim 8 for mounting the foamed tire 1 with a bead core, for example, the interference is 0 to 0 in the axial bead interference as shown in the following equation.
It is set to 15%, 0 to 5% for the radial bead large diameter interference, and 5 to 15% for the bead small diameter interference. Axial bead interference = (BW-LW) / LW x 100 =
0 to 15% Bead large diameter interference = (RD2-BD2) / RD2 × 10
0 = 0 to 5% Bead small diameter interference = (RD1-BD1) / RD1 x 10
0 = 5 to 15% Here, BW is the bead width, LW is the rim width, RD2 is the rim large diameter, BD2 is the bead large diameter, RD1 is the rim small diameter, BD1
Is a small bead diameter.

If the axial bead interference is less than 0%, idling between the foamed tire 1 and the rim 8 tends to occur, which is not preferable. If it exceeds 15%, the rim 8 becomes difficult to assemble. If the bead large diameter interference in the radial direction is 0% or less, slipping between the foamed tire 1 and the rim 8 is likely to occur, and if it exceeds 5%, the rim 8 becomes difficult to assemble, which is not preferable. Similarly, if the bead small diameter allowance is less than 5%, the tire 1 and the rim 8 are liable to idle, which is not preferable. If it is more than 15%, the rim 8 becomes difficult to assemble, which is not preferable.

The inner peripheral length of the bead core 6 is preferably set to 1.01 to 1.05 times the outer peripheral length of the rim 8 (= rim diameter RD2 × π). If the inner peripheral length of the bead core 6 is less than 1.01 times the outer peripheral length of the rim 8, it is not preferable because the foamed tire 1 becomes difficult to assemble to the rim 8. 1. The outer peripheral length of the rim 8
When it is 05 times or more, the fitting force between the foamed tire 1 and the rim 8 decreases, which is not preferable. When the fitting force is reduced, slipping is likely to occur, or when an irregular and excessive load acts in the axial direction of the foamed tire 1, the foamed tire 1 may come off the rim 8, which is not preferable. In particular, when the bead core 6 is not provided, it is likely to come off.

It is preferable that the total width of the bead core 6 is 10 to 20% of the width LW of the rim 8. The total width is a value obtained by multiplying the width of one bead core 6 in the tire axial direction by the number of bead cores 6. If the total width of the bead core 6 is 10% or less with respect to the width LW of the rim 8, the fitting force between the foamed tire 1 and the rim 8 decreases, which is not preferable. When the fitting force is reduced, slipping is likely to occur, or an irregular and excessive load is applied to the foamed tire 1.
When acting in the axial direction, the foamed tire 1
May undesirably come off. If the width is 20% or more with respect to the width LW of the rim 8, the foamed tire 1 becomes difficult to assemble to the rim 8, which is not preferable.

As shown in FIG. 2, the bead core 6 may be formed by flipping with a covering member 6a such as a barbed cord or chafer.
Not limited to flippering, wrapping may be used. For example, in the case where the bead core 6 is a strand wire formed by winding a large number of bead wires, it is possible to prevent the bead core 6 from being loosened during vulcanization and the bead core 6 from being further broken during running, and to prevent the bead core 6 from being rubberized. Good adhesion can be maintained. Similarly, even in the case of the bead core 6 composed of one bead ring, it is possible to maintain good adhesion of the running bead core 6 to the rubber portion.

The position of the bead core 6 in the tire axial direction is at least 1 m from the side surface of the foamed tire 1.
It is preferably m inside. By arranging at least 1 mm inside, a rim shift occurs and the
Even if the surface is scratched or worn, the bead core 6 is at least 1 mm thick and protected, so that the durability is excellent. If the thickness is 1 mm or less, the durability tends to decrease, which is not preferable. As shown in FIG. 4, the entire bead core 6 may be covered with the surface layer 4. In this case as well, the durability is excellent, and in the case of a strand wire, the bead is prevented from running off. , Durability is improved.

Further, as shown in FIG. 5, the base side in contact with the rim 8 may be covered with a non-foamed base rubber layer 10. The bead core 6 is arranged in the base rubber layer 10. Thereby, the bead core 6 is restrained, the holding force in the foamed tire 1 is improved, and the durability of the foamed tire 1 is also improved. At this time, as shown in FIG.
0 may be covered with the surface layer 4.

The base rubber layer 10 preferably has a height with respect to the total height H of the tire of 10 to 30%, and if the height is less than 10%, the ability to hold the bead core 6 is reduced. This is not preferable because the cushioning property of the rubber 1 itself tends to decrease.

JIS-K6253 of the base rubber layer 10:
Type A Durometer hardness test shows hardness of A40-100
When the temperature is 40 degrees or less, the ability to hold the bead core 6 is reduced, which is not preferable. When the temperature is 100 degrees or more, the cushioning property of the foamed tire 1 itself tends to decrease, which is not preferable. On the other hand, if the temperature is 100 degrees or more, the quality becomes excessive, which is not preferable.

The surface layer 4 contains 1 to 3 PHR of waxes, and particularly preferably 1.5 to 2.5 PHR. 1P
If it is below HR, cracks are likely to occur during use due to ozone deterioration, sunlight deterioration, etc., which is not preferable.
Above this, bloom becomes too large, which is not desirable in appearance, and also leads to excessive quality, which is not desirable. The waxes may be sun crack inhibitors, such as microcrystalline wax. Since the tire of the present invention expands from the mold size after vulcanization, the rubber on the tire surface always expands and is in a tension state, and during use, cracks easily occur due to ozone deterioration, sunshine deterioration, etc., and more effectively by waxes Can be suppressed.

[0029] The waxes are waxes having a capability of suppressing the generation and growth of cracks due to ozone and sunlight when incorporated into rubber, and are used as sun crack inhibitors. The effect is to bloom on the surface of the rubber after vulcanization to form a wax film, to block ozone and the like, and to protect the rubber by reflecting sunlight.

The rubber composition of the surface layer 4 is such that natural rubber and SBR are blended in a weight ratio of 13: 1 to 2: 1 as a polymer and the styrene content in the SBR is 5 to 15% by weight. . In addition, white carbon is used as a reinforcing material.
0PHR blended and carbon black as FEF
20-40 PHR class and 15-35 HAF class
PHR is blended with at least these two types of carbon black. In addition, in order to improve wear resistance,
It is particularly preferable to use a high structure type carbon black.

By using such a rubber composition, the abrasion resistance (tread side) of the surface layer rubber is improved, the rim slippage (side side) is reduced, and the crack and chipping resistance is further improved. It tends to reduce rolling resistance, and also has a tendency to ensure appropriate rigidity. The styrene content in the SBR is 5 to 15% by weight, and by using such a styrene content, both low rolling resistance and crack and chipping resistance can be achieved.

The rubber composition of the foamed layer 2 is such that natural rubber and SBR are blended in a weight ratio of 7: 3 to 3: 7 as a polymer component, and the HAF class is 20 to 5 as carbon black.
0PHR is used. By foaming with such a rubber composition, appropriate various rigidities (longitudinal rigidity / lateral rigidity) and elasticity (cushioning property) of the foamed tire 1 can be secured in a well-balanced manner. At the same time, flat spots can be prevented. Furthermore, it has excellent long-term durability. Further, unlike the urethane foam, the diene rubber is used, so that there is no hydrolysis even if moisture enters inside due to a wound such as a nail sting or the like.

The foamed layer 2 contains a nitrogen-based foaming agent at 2 to 10 PH.
R, beforehand forming an unvulcanized rubber molded article for a foaming layer to be a foamed layer 2 in advance, and further an unvulcanized rubber for a surface layer to be a non-foamed surface layer on the unvulcanized rubber molded article for a foamed layer And vulcanize it at 140-180 ° C. at a temperature of 140 to 180 ° C. (the time is 20 to 60 minutes and the longer the tire, the longer it is).

In the production of the bead core-containing foamed tire 1, it is necessary to specify the types and amounts of the rubber and the foaming agent, vulcanization conditions, and the like, and a good tire can be obtained only when these are balanced. The foaming agent is nitrogen-based, and 4,4'-
Oxybisbenzenesulfonyl hydrazide (OBS
H), dinitrosopentamethylenetetramine (DP
T), azodicarbonamide (ADCA), paratoluenesulfonyl hydrazide (TSH), or azobisisobutyronitrile (AIBN) is preferably used.

The mixing ratio of the rubber and the foaming agent is 100
2 to 10 parts by weight (PHR) of a foaming agent with respect to parts by weight, and 2 to 5 parts by weight (PHR) when an auxiliary agent is used in combination.
When used alone, 5 to 10 parts by weight (PHR) is preferred.
In addition, the rubber is usually compounded with carbon black, a softener, an antioxidant, a vulcanizing agent, and the like.

For kneading the compound, first, a rubber compound excluding a foaming agent is prepared by using a closed mixer such as an intermix, a Banbury mixer, a kneader, or an open roll. Subsequently, the foaming agent is added and kneaded using an open roll, a kneader or the like at a temperature not higher than the decomposition temperature of the foaming agent (usually 80 ° C. or lower) to prepare a final rubber compound. Alternatively, a kneaded product excluding a vulcanizing system, that is, a vulcanizing agent and a vulcanization accelerator, a vulcanization retarder (scorch adjusting agent), etc., is first kneaded, and then the vulcanizing agent and the vulcanization accelerator / vulcanizing agent are kneaded. When the sulfur retarder (scorch adjuster) is added and kneaded, the foaming agent may be added and kneaded at the same time or lower than the decomposition temperature of the blowing agent (usually 80 ° C. or lower).

The compound after the kneading is heated by a roll and discharged, or the sheet is discharged using an extruder or the like to form a green. FIG.
As shown in (a), the unvulcanized rubber sheet 12 for the foam layer is wound around the drum 11, and the unvulcanized rubber sheet 14 for the surface layer is further wound around the outer periphery thereof (FIG. 7 (b)). Then, the bead cores 6 are attached to both sides, and the unvulcanized rubber sheets 16 for the surface layer on the side are further attached to both side surfaces thereof (FIG. 7).
(C)), the excess part is cut out and molded (FIG. 7)
(D)).

The molded green is placed in a mold and vulcanized. The vulcanization temperature is 140-180 ° C, preferably 150-
170 ° C. The vulcanization time is about 20 to 60 minutes (depending on the tire size: the longer the size, the longer), particularly preferably 30 to 50 minutes. These vulcanization conditions affect not only the vulcanization of the rubber but also the foaming situation. If the temperature is lower or the time is shorter than this, the decomposition and foaming reaction of the foaming agent does not proceed, and the foaming ratio tends to decrease.

The vulcanized product is allowed to stand for one to two days to stabilize its dimensions. As a result, the finished product can have improved dimensional accuracy. The foamed tire 1 expands and contracts once when it is taken out of the vulcanizing mold. However, even if contracted, the size is larger than the original mold size.

As a manufacturing method, as shown in FIG. 8, the unvulcanized rubber 22 for the foam layer and the unvulcanized rubber 22 for the foam layer are used.
The unvulcanized rubber for surface layer 24 covering at least the tread side and the side side is extruded into a rod shape by a double extruder. Then, the rod-shaped molded product 26 is rolled into a ring shape, and then the unvulcanized rubber 24 for the surface layer is turned over, the bead core 6 is inserted into both sides, and then vulcanized.
May be manufactured.

Next, the mixing ratio of the unvulcanized rubber 24 for the surface layer used in the present embodiment is shown in Table 1, and the unvulcanized rubber 22 for the foam layer is shown in Table 1.
Is shown in Table 2.

[0042]

[Table 1]

[0043]

[Table 2] In addition, Table 3 shows the physical properties of the surface layer 4 having the above composition. still,
Physical property data was tested according to JIS K6301-1975 and others. The hardness of the foam layer 2 is 52 degrees in a JIS-K7312, type C hardness test.

[0044]

[Table 3] The longitudinal spring constant of the bead core-containing foamed tire 1 is 4 to 6 kgf /
mm is preferred. If it is smaller than this, the rigidity of the tire is insufficient, rim deviation is likely to occur, and durability may decrease, which is not preferable.If it is larger than this, the tire becomes too hard, the vibration absorption performance decreases, and the riding comfort decreases. It is not preferable.

Various tests were carried out using the bead core-containing foamed tire manufactured under the above-mentioned composition and conditions. In the tire compression test, a predetermined load was applied to the test tire, the load-strain relationship was plotted, and the riding comfort performance was compared. As a result, almost the same performance as that of the pneumatic tire was obtained.

In the overshoot test, the test tire is mounted on the left rear wheel of the electric car, and the vehicle travels. Comfort performance was compared. As a result, almost the same performance as that of the pneumatic tire was obtained.

In the flat spot test, a test tire in which a flat spot was previously generated in a low-temperature environment was mounted on the left rear wheel of an electric car and traveled. The vibration caused by the flat spot was measured by an acceleration converter attached to the vehicle. The measurement was performed to compare the recoverability of the flat spot and the magnitude of the influence exerted during running of the vehicle. As a result, almost the same performance as that of the pneumatic tire was obtained.

In the abrasion resistance test, the test tire was mounted on the left rear wheel of the electric car at the beginning of the test and then run, and the amount of wear was compared (the right rear wheel is a comparative pneumatic tire). The tire mounting position was changed left and right every 8 hours of running, and the tire outer diameter was measured with calipers at the time of tire replacement. FIG. 9 shows the result of comparison with the pneumatic tire. The bead core-containing foamed tire 1 of the present embodiment is more excellent in wear resistance than the pneumatic tire. Further, there is no slip, and even when an irregular and excessive load is applied in the axial direction, the fitting force is strong, so that the foamed tire 1 does not come off the rim 8.

The present invention is not limited to such an embodiment at all, and can be implemented in various modes without departing from the gist of the present invention.

[0050]

As described above in detail, the bead core-containing foamed tire of the present invention maintains various performances relating to durability, such as sufficient rigidity, rim slip resistance, abrasion resistance, and sufficient fitting force to the rim. It has the effect of having a sufficient ride comfort required. Further, according to the production method of the present invention, a foamed tire containing a bead core can be suitably produced.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a foamed tire including a bead core as one embodiment of the present invention.

FIG. 2 is a cross-sectional view of a bead core-containing foamed tire obtained by flipping a bead core as one embodiment of the present invention.

FIG. 3 is a cross-sectional view of a foam core-containing foamed tire having a surface layer also formed on a rim side as one embodiment of the present invention.

FIG. 4 is a cross-sectional view of a bead core-containing foamed tire in which a bead core as one embodiment of the present invention is arranged in a surface layer.

FIG. 5 is a cross-sectional view of a foamed tire including a bead core on which a base rubber layer is formed as one embodiment of the present invention.

FIG. 6 is a cross-sectional view of a foamed tire including a bead core having a surface layer also formed on the side of a base rubber layer as one embodiment of the present invention.

FIG. 7 is an explanatory diagram showing a manufacturing process order of a foamed tire containing a bead core as one embodiment of the present invention.

FIG. 8 is an explanatory view illustrating a method for manufacturing a bead core-containing foamed tire as another embodiment of the present invention.

FIG. 9 is a graph showing a wear amount of a bead core-containing foamed tire and a pneumatic tire as one embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Foamed tire containing a bead core 2 ... Foam layer 4 ... Surface layer 6 ... Bead core 6a ... Coating member 8 ... Rim 11 ... Drum 12 ... Unvulcanized rubber sheet for foam layer 14, 16 ... Unvulcanized rubber sheet for surface layer 22 ... unvulcanized rubber for foam layer 24 ... unvulcanized rubber for surface layer 26 ... rod-shaped molded product

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (Reference) B60C 15/06 B60C 15/06 CD (72) Inventor Kazuyoshi Ueno 1108 Otsubo, Takuraku-cho, Kasugai-shi, Aichi Aichi Tire (72) Inventor: Tatsu Murata 1108, Otsubo, Dakuraku-cho, Kasugai-shi, Aichi F-term (reference) 4F212 AA46 AG20 AH20 VC07

Claims (13)

[Claims] 1. A foam layer having an expansion ratio of 1.5 to 2.5 times is covered with a non-foamed surface layer at least on the tread side and the side side, and the thickness of the surface layer on the side side is 2 to the tire width.
８8%, the thickness of the surface layer on the tread side is formed to 5-15% with respect to the tire height, and the JIS of the surface layer
-K6253: hardness is A45 to 65 degrees in a type A durometer hardness test, JIS-K7312: hardness of the foam layer is HsC40 to 70 degrees in a type C hardness test, and 100% elongation of the surface layer. 1.5 tensile stress
A foamed tire including a bead core, wherein the surface layer and the foamed layer are formed of a diene rubber, and a plurality of bead cores are arranged at symmetric positions with respect to the tire equatorial plane. 2. The foamed tire with a bead core according to claim 1, wherein the inner peripheral length of the bead core is 1.01 to 1.05 times the outer peripheral length of the rim. 3. The foamed tire with a bead core according to claim 1, wherein a total width of the bead core is 10 to 20% with respect to a rim width. 4. The foamed tire with a bead core according to claim 1, wherein the bead core is formed by being covered with a covering member. 5. At least 1 m from the side surface
The foamed tire containing a bead core according to claim 1, wherein the bead core is arranged inside m. 6. The foamed tire with a bead core according to claim 1, wherein the bead core is provided in the side surface layer. 7. The base side in contact with the rim is covered with a non-foamed base rubber layer, the height of the base rubber layer relative to the total height of the tire is 10 to 30%, and the base rubber layer is JIS-K62.
53: Type A durometer hardness test shows hardness of A40 ~
The bead core-containing foamed tire according to any one of claims 1 to 6, wherein the angle is 100 degrees. 8. The interference when mounting the rim is 0 to 15% for the axial bead interference, and 0 to 5 for the radial bead large diameter interference.
The bead core-containing foamed tire according to any one of claims 1 to 7, wherein the bead core diameter is 5 to 15%. 9. The method according to claim 1, wherein the surface layer is made of a wax containing 1 to 3 PHR.
The foamed tire with a bead core according to claim 1, wherein the foamed tire contains a bead core. 10. The surface layer comprises natural rubber and SBR in a weight ratio of 13: 1 to 2: 1 and the SBR.
The content of styrene in the mixture is 5 to 15% by weight, white carbon is blended at 1 to 10 PHR, and FE
F-class carbon black with 20-40 PHR and HA
The carbon black of F class is blended at 15 to 35 PHR and molded.
The foamed tire containing the bead core according to the above. 11. The foamed layer is formed by blending natural rubber and SBR at a weight ratio of 7: 3 to 3: 7 and blending HAF class carbon black at 20 to 50 PHR. The foamed tire containing a bead core according to claim 1. 12. Rolling an unvulcanized rubber sheet for a foam layer,
A method for producing a foamed tire with a bead core, comprising: attaching bead cores to both side surfaces thereof; covering the unvulcanized rubber for a surface layer with the bead cores; 13. An unvulcanized rubber for a foamed layer and an unvulcanized rubber for a surface layer covering at least a tread side and a side of the unvulcanized rubber for a foamed layer are extruded into a rod shape by a double extruder. A method for producing a foamed tire with a bead core, comprising: rolling the rod-shaped molded product into a ring shape; inserting a bead core into both sides of the unvulcanized rubber for the side surface layer;