JP2002362108A - Foamed solid tire and its manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the wear resistance of a foamed solid tire having a foamed rubber. SOLUTION: The foamed solid tire having a tire body 5 provided with the circular foamed rubber comprises a non-foamed rubber layer 7 formed on an outer periphery face 5b of the tire body, the non-foamed rubber layer 7 becoming a tread portion.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a foamed solid tire having improved abrasion resistance and a method for producing the foamed solid tire.

[0002]

2. Description of the Related Art Japanese Patent Application Laid-Open No. 11-189001 discloses that
A soft tire in which a thick elastic layer having a flat outer peripheral surface made of an elastomer foam is fixed to the outer peripheral surface of a metal wheel. In general, when foamed rubber is used for a tire, ride comfort can be improved and a friction coefficient can be increased.

[0003]

However, since foamed rubber has poor abrasion resistance, when it is used for a tire tread,
There is a problem that the life of the tire is shortened. On the other hand, in a solid tire, when ordinary rubber used for a tire is used instead of foamed rubber, there is a problem that abrasion resistance is obtained but riding comfort is deteriorated. The present invention
It is made in view of such a problem, and aims at improving abrasion resistance in a foamed solid tire having foamed rubber.

[0004]

The present invention employs the following technical means. That is, a feature of the present invention is that in a foamed solid tire having a tire body in which foamed rubber is formed in an annular shape, a non-foamed rubber layer is formed on an outer peripheral surface of the tire body, and the non-foamed rubber layer is used as a tread portion. There is in the point. According to this configuration, the wear resistance of the foamed solid tire is ensured by the non-foamed rubber layer on the outer peripheral surface of the tire body.

[0005] The foamed rubber of the tire body may be natural rubber,
The hollow former material is used in an amount of 0.5 to 15 parts by weight per 100 parts by weight of a polymer component selected from the group consisting of a conjugated diolefin homopolymer, a copolymer of a conjugated diolefin and an ethylenically unsaturated monomer, and a mixture thereof. Preferably, the rubber composition contains 0 parts by weight. If the added amount of the hollow forming substance is less than 0.5 parts by weight, effective foaming cannot be expected and the specific gravity increases, which hinders weight reduction. If the added amount is more than 15.0 parts by weight, it is disadvantageous in cost. Become.

Further, a feature of the present invention relating to a method for manufacturing a foamed solid tire is that a foamed vulcanizing step of foaming a rubber composition containing a foaming agent is performed to form the rubber composition in advance into a predetermined shape, and then the foamed rubber is formed. Is to perform a finishing vulcanization step of affixing an unvulcanized rubber to the rubber and vulcanizing the foam rubber to which the unvulcanized rubber is affixed. As described above, by separating the foaming vulcanization step and the finish vulcanization step, the production becomes easy and the optimum foaming state can be realized. Here, the charged amount of the rubber composition before foam vulcanization in the foam vulcanization mold for performing the foam vulcanization step is 20 to 20 times the mold internal space.
Preferably it is 95%. In the foam vulcanization process,
It is preferred that the vulcanization be completed before foaming of the rubber composition containing the foaming agent is completely completed, and that foaming be completed in a subsequent vulcanization step.

Furthermore, it is preferable to use a gas-filled thermoplastic elastomer balloon as the foaming agent.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a tire wheel 3 in which a foamed solid tire 1 is mounted on a wheel core 2 such as a rim or a core bar.
Is shown. The foamed solid tire 1 is used for a flat tire, forklift, tractor, shovel loader, wheelchair, bicycle, cart, and the like. FIG.
As shown in the cross-sectional view of FIG.
Has a tire main body 5 made of foamed rubber. The tire main body 5 is formed in an annular shape, and the inner peripheral surface 5 a side thereof is attached to the wheel core 2. The tire wheel 3 has a wheel core 2 attached to an axle of a vehicle.

The inner peripheral surface 5a of the tire body 5 has a thickness of 2 m.
About m of the adhesive sheet layer 6 is provided, the adhesive sheet layer 6 is adhered to the wheel core 2 via an adhesive, and the tire main body 5 is attached to the wheel core 2. In addition,
The adhesive sheet layer 6 is a non-foamed rubber,
Can be omitted. Outer peripheral surface 5b of tire body 5
The non-foamed rubber layer 7 is formed on the side surface 5c. Of the non-foamed rubber layer 7, the one formed on the outer peripheral surface 5b, which is a tread, in particular, is important for improving the wear resistance of the tire 1, and natural rubber, which is generally used for tire tread rubber, Rubber components such as polyisoprene rubber, polybutadiene rubber, and styrene-butadiene copolymer rubber are used.

[0010] The unfoamed rubber layer 7 has a thin skin shape so as not to impair the ride comfort obtained by the tire body 5 which is foamed rubber. In addition, a certain thickness is required to secure wear resistance. From such a viewpoint, the thickness of the rubber layer 7 is preferably set to 1 mm or more. The thickness of the rubber layer 7 is preferably equal to or less than the thickness (length in the radial direction) of the tire body 5 so that the thickness of the rubber layer 7 is not excessively large and the ride comfort is not deteriorated. Specifically, the thickness of the rubber layer 7 can be about 10 mm. FIG.
FIG. 2 shows a partial cross-sectional view of a tire wheel 13 having a foamed solid tire 11 of another embodiment, and shows a rim 1 as a wheel core.
The non-foamed rubber layer 17 is attached to the outer peripheral surface 15b of the tire main body 15 made of foamed rubber, and the side portion 15c of the tire main body 15 is A rubber layer 18 is separately attached. The rubber layer 18 may be a foamed rubber layer 17 or a non-foamed rubber layer.

The tire bodies 5, 15 as shown in FIGS.
Is a rubber composition containing a foam-forming substance as a foaming agent in a rubber composition. The rubber composition is selected from the group consisting of natural rubber as a polymer component (rubber component), a homopolymer of a conjugated diolefin, a copolymer of a conjugated diolefin and an ethylenically unsaturated monomer, and a mixture thereof. Specific rubber components include polyisoprene rubber, emulsion polymerized styrene-butadiene copolymer rubber, solution polymerized styrene butadiene copolymer rubber, low cis polybutadiene rubber, high cis polybutadiene rubber,
Styrene-isoprene copolymer rubber, butadiene-isoprene copolymer rubber and the like can be mentioned.

The hollow forming substance contained in the polymer component is used in an amount of 0.5 to 1 based on 100 parts by weight of the polymer component.
5.0 parts by weight are preferred. The addition amount of the hollow forming substance is 0.
If the amount is less than 5 parts by weight, effective foaming cannot be expected, and if the amount is more than 15.0 parts by weight, it is disadvantageous in terms of cost. Hollow forming substance (gas-filled thermoplastic resin particles)
May form a hollow after vulcanization, and may not have a hollow before vulcanization. As the hollow forming substance, a substance containing an organic substance which easily vaporizes in the range of 100 ° C. to 180 ° C. in an organic polymer film (referred to as microballoon or foamed microcapsule) is preferably used.

[0013] The rubber composition comprising a tire body, foam void average volume after vulcanization is foamed so as to be ^{1 × 10 4 μm 3 ~5 ×} 10 7 μm 3 range. Foam void average volume is 1
If it is less than × 10 ⁴ μm ³ , the cushioning properties are poor, and the contribution of foaming to tire performance cannot be expected. If it is more than 5 × 10 ⁷ μm ³ , the tensile strength is disadvantageous. FIG. 3-
FIG. 6 shows a foamed solid tire 1 as shown in FIG. 1 or FIG.
11 shows a manufacturing process of a laminated solid tire of a foamed rubber and a normal rubber that is not. However, although the basic structure of the foamed solid tire is the same, the shape is different from FIGS. 1 and 2.

When a foamed solid tire is manufactured, when ordinary rubber is laminated and vulcanized and foamed on a rubber composition containing a foaming agent, the volume increases due to foaming. It is necessary to reduce the amount of the rubber composition charged to the mold that performs sulfurization. But,
If the charged amount is reduced, a problem arises that a bear is generated due to an insufficient load, or that the pressure for bonding the foamed rubber and the normal non-foamed rubber is insufficient. Also, the shape of the product is not stable. As a result, it is difficult to manufacture a laminated solid tire.

In the manufacturing method shown in FIGS. 3 to 6, the foam vulcanization step and the finish vulcanization step are separated to form a two-stage vulcanization method in order to easily manufacture a laminated solid tire. In order to foam a rubber composition having a foaming agent as shown in FIG.
The foaming vulcanization step using the foam vulcanization molds 20, 21 is performed as preliminary vulcanization. This foam vulcanization mold is
It has a pair of upper and lower parts, and has annular cavities 22 and 23 divided into two parts in the wheel axis direction. In the cavities 22 and 23, a rubber composition to be the rubber bodies 5 and 15 is charged. The charged amount of the rubber composition is set to 20% to 95% of the cavity volume (volume inside the mold). If it is less than 20%, the bear after foaming and insufficient volume will occur,
If it is 96% or more, sufficient foaming cannot be obtained. Preferably, a rubber composition (hereinafter, also referred to as “foamed member”)
Is 50% to 80%. In addition, as a foaming agent, a balloon type by expansion of a gas sealed in a thermoplastic elastomer thin film is used.

[0016]

[Table 1]

Table 1 shows the effects of the mold charging rate of the foamed member and the pre-vulcanization of the foamed member on the product. In Comparative Example 1, "no foaming" was found as a defect to the product.
Was the result. In Comparative Examples 2 and 3, the result was "insufficient product". In Example 1, no defect in the product was observed. Cavities 22, of foam vulcanization molds 20, 21
Reference numeral 23 is formed in a shape corresponding to the tire main bodies 5 and 15, and vulcanizes only the foamed rubber in the foam vulcanization molds 20 and 21 as preliminary vulcanization. In the foaming vulcanization step, foaming of the rubber composition having a foaming agent is not completely completed, but is completed when foaming is about 90%. The foamed rubber is taken out of the molds 20 and 21 and naturally cooled. At this time, the foaming proceeds due to the residual heat, but if the foaming is terminated at about 90%, the foaming is not completely completed even if the foaming occurs due to the residual heat.

In the foam vulcanization step, the rubber torque was 6.0 (N · c) as measured by a curast tester.
m), the vulcanization temperature is set so that 70% or more of the foaming is completed within the time period (however, in the actual product manufacturing process, the torque at the time when the foaming of the rubber in the mold is 70% or more is completed). The minimum value may be 6.0 (N · cm).) If it is larger than 6.0 (N · cm), the elasticity of the rubber is too large, and foaming is hindered. The unvulcanized rubber 25 to be the non-foamed rubber layers 7, 17 and the like is stuck to the foamed rubber (tire body 5, 15) thus obtained and formed into a predetermined shape. The foamed rubbers 5 and 15 to which the unvulcanized rubber 25 has been attached are charged into finish vulcanizing molds 26 and 27 and subjected to finish vulcanization (see FIG. 4). The cavities 28, 29 of the finish vulcanization molds 26, 27 are
It is formed in a shape corresponding to the shape of the foamed solid tires 1 and 11, and vulcanization of the foamed rubbers 5 and 15 and the non-foamed rubber layers 7 and 17 is performed as the main vulcanization. Also in this finish vulcanization, the foamed rubbers 5 and 15 are foamed, so that the foamed rubbers 5 and 15 further expand, and a pressure for forming the tires 1 and 11 into a predetermined shape is obtained (see FIG. 5). As described above, by separating the foaming (vulcanizing) step and the finishing vulcanizing step, an optimum foaming state can be easily realized, and the solid foam tires 1 and 11 can be easily produced.

The tires 1 and 11 which have completed the finishing vulcanization process are mounted on rims 2 and 12 to become tire wheels 3 and 13 (see FIG. 6).

[0020]

The rubber composition of the foamed rubber is shown in Table 2.

[0021]

[Table 2]

In Table 2, NB is natural rubber, and SBR is styrene butadiene copolymer rubber (Nipol 150).
2 (emulsion SBR): ZEON CORPORATION, CB: carbon black (SHOWBLACK N351: manufactured by Showa Cabot), zinc oxide: 3 types of zinc oxide: Mitsui Kinzoku Mining Co., Ltd., antioxidant 6C: antiaging agent (antigen 6C: Sumitomo Chemical Co., Ltd.), and the oil is an aromatic oil (Process X-140: Japan Energy Co., Ltd.). In the formulations in Table 2, the microballoons are variable, and the microballoons are trade names
el.

In Table 2, "TB (MPa)"
Is the result of measuring the tensile strength (JIS K6301). Further, the “average void volume (μm ³ )” is a result of measuring the average volume of the voids formed by the microballoons. The average void volume is obtained by slicing the foamed rubber, measuring with a microscope, and determining the diameter. It is calculated. “Cost” is an index with Comparative Example 1 being 100, and the higher the number, the higher the cost.

The "specific gravity" is calculated based on a change in weight of a sample in water, with the specific gravity of water being 1.000.
In Table 2, Comparative Example 1 does not include microballoons. In Comparative Example 2, since the addition amount of the microballoon was as small as 0.10 parts by weight, effective foaming was not obtained, and the specific gravity was large. If the specific gravity is large,
It is not preferable because it hinders the weight reduction of the product. Comparative Example 3 is disadvantageous in cost because the added amount of the microballoon is as large as 16.00 parts by weight.

On the other hand, in Examples 1 to 4 in Table 2, good results were obtained. Note that the present invention is not limited to the above embodiments and examples, and various modifications can be made within the scope shown in the claims.

[0026]

According to the present invention, the abrasion resistance of a foamed solid tire having foamed rubber can be improved.
Further, according to the production method of the present invention, since the foam vulcanization step and the finish vulcanization step are separated, the production is easy and an optimum foaming state can be realized.

[Brief description of the drawings]

FIG. 1A is a schematic side view of a foamed solid tire, and FIG. 1B is a sectional view taken along line AA of FIG.

FIG. 2 is a partial cross-sectional view of a foamed solid tire according to another embodiment.

FIG. 3 is a diagram showing a manufacturing process of a foamed solid tire.

FIG. 4 is a view showing a manufacturing process of a foamed solid tire.

FIG. 5 is a view showing a manufacturing process of a foamed solid tire.

FIG. 6 is a sectional view showing a completed foamed solid tire.

[Explanation of symbols]

 Reference Signs List 1 foam solid tire 5 foam rubber (tire body) 7 non-foam rubber layer 11 foam solid tire 15 foam rubber (tire body) 17 non-foam rubber layer

Continued on front page F-term (reference) 4F074 AA06 AA08 AA17 BB01 CB62 CB76 CC06Y CC07Y CC07Z CE02 CE87 DA20 DA59 4F212 AA03 AA45 AB03 AB19 AG02 AG20 AH21 UA01 UA09 UB01 UB13 UB22 UN03 UN05 UN09 VC07 VA03 VC06

Claims (6)

[Claims] 1. A foamed solid tire having a tire body (5) in which foamed rubber is formed in an annular shape, wherein a non-foamed rubber layer (7) is formed on an outer peripheral surface of the tire body (5); (7) A foamed solid tire, wherein the tread portion is provided. 2. The foamed rubber of the tire body (5) is a polymer selected from the group consisting of natural rubber, a homopolymer of a conjugated diolefin, a copolymer of a conjugated diolefin and an ethylenically unsaturated monomer, and a mixture thereof. For every 100 parts by weight of the component, 0.5 to 1
The foamed solid tire according to claim 1, which is a rubber composition containing 5.0 parts by weight. 3. The method for producing a foamed solid tire according to claim 1, wherein a foaming vulcanization step of foaming a rubber composition containing a foaming agent is performed to form the rubber composition in a predetermined shape in advance. A method for producing a foamed solid tire, comprising: applying an unvulcanized rubber to the foamed rubber; and performing a finishing vulcanization step of vulcanizing the foamed rubber to which the unvulcanized rubber is attached. 4. The charged amount of the rubber composition before foam vulcanization in the foam vulcanization mold for performing the foam vulcanization step is 20 to 95% of the internal space of the mold. A method for producing the foamed solid tire as described above. 5. In the foam vulcanization step, vulcanization is terminated before foaming of a rubber composition containing a foaming agent is completely completed, and foaming is completed in a subsequent finish vulcanization step. The method for producing a foamed solid tire according to claim 3 or 4, wherein: 6. The method according to claim 3, wherein a gas-filled thermoplastic elastomer balloon is used as the foaming agent.