JPH1148708A - Manufacture of tread member and manufacture of pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently manufacture a tread member used in a tread formed in a layered structure of different nature layer. SOLUTION: A first sheet-shaped member 24 formed in high wear resistant rubber by vulcanization and a second sheet-shaped member 26 formed in low wear resistant rubber by vulcanization are fixed together, a layered sheet member 28 is obtained. This layered sheet member 28 is bent in zigzag shape by being passed through a guide 30 having a slit hole 32 with a hole sectional shape gradually changing from a straight line to zigzag shape in accordance with going toward an outlet 32B from an inlet 32A, whose opening shape extends in a straight line in slit shape while an opening shape of an outlet 32B bends in zigzag. When the layered sheet member 28 bent in zigzag shape is passed through between a rotating upper roll 36 and small diametric part 38A of a rotating lower roll 36, a thick tread member 40 is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for manufacturing a tread member and a method for manufacturing a pneumatic tire, and more particularly to a method for manufacturing a tread member used for a pneumatic tire and a method for manufacturing a pneumatic tire for manufacturing a pneumatic tire.

[0002]

2. Description of the Related Art In recent years, studless tires have been used as tires having improved performance on ice and snow.

[0003] A block pattern composed of a plurality of blocks is formed on the tread of this type of studless tire in order to improve the performance on snow.

In order to improve the performance on ice, the tread of this type of studless tire uses a rubber material that is more flexible than a normal tire in order to obtain a frictional force with an icy road surface.

[0005]

It is conceivable to make the rubber material of the tread softer in order to further improve the performance on ice, but there is a limit because problems such as a decrease in block rigidity and a decrease in wear resistance occur. . In addition, it is conceivable to use many sipes, but there is a limit to the excessive use of sipes because it leads to uneven wear and a decrease in block rigidity.

On the other hand, a pneumatic tire having a relatively large number of relatively shallow narrow grooves formed on a tread surface has been proposed. However, since the narrow grooves disappear due to wear, the wet performance and the performance on ice due to the narrow grooves are not improved. It can only be obtained at an early stage.

Therefore, the tread has a laminated structure of layers having different properties, for example, a structure in which rubber layers having different abrasion resistances are laminated along the tire width direction, or a structure in which a rubber layer and a nonwoven fabric are laminated along the tire width direction. Then, by running,
Lower the abrasion resistant rubber layer lower than the high abrasion resistance rubber layer or lower the nonwoven fabric layer than the rubber layer to form and maintain shallow narrow grooves on the tread surface to improve wet performance and ice performance. It can be improved.

However, in order to form a tread having a laminated structure of layers having different properties, it is conceivable to laminate layers having different properties one by one, but this is not very efficient.
There is a problem that the manufacturing cost is high. There is also a problem that the cost of the pneumatic tire naturally increases.

In view of the above facts, the present invention provides a method for manufacturing a tread member and a method for manufacturing a pneumatic tire, which can efficiently manufacture a tread member used for a tread having a laminated structure of layers having different properties. The purpose is to do.

[0010]

According to a first aspect of the present invention, there is provided a method of manufacturing a tread member, comprising the steps of laminating a plurality of types of sheet members having different properties to each other to form a laminated sheet member; Bending in a zigzag shape and bringing the surfaces facing each other into close contact to form a thick tread member.

Next, the operation of the method for manufacturing a tread member according to the first aspect will be described. First, in the first step, a laminated sheet member is formed by laminating a plurality of types of sheet members having different properties from each other.

Next, the laminated sheet member is folded in a zigzag shape, and the surfaces facing each other are brought into close contact with each other, whereby a thick tread member having a laminated structure of layers having different properties can be easily obtained. That is, the tread member can be manufactured very efficiently as compared with the lamination method one by one.

According to a second aspect of the present invention, there is provided a method for manufacturing a tread member, which comprises vulcanizing a first sheet-like member made of a first unvulcanized rubber composition which becomes a highly wear-resistant rubber. The second sheet-shaped member made of the second unvulcanized rubber composition or a material other than rubber which becomes a low wear-resistant rubber having a lower wear resistance than the high wear-resistant rubber. Forming a laminated sheet member by laminating any one of the third sheet members having lower wear resistance than the conductive rubber, and bending the laminated sheet member in a zigzag shape to bring the surfaces facing each other into close contact with each other. And forming a thick tread member.

Next, the operation of the method for manufacturing a tread member according to the second aspect will be described. First, in the first step, a first sheet-shaped member made of a first unvulcanized rubber composition that becomes a highly wear-resistant rubber by vulcanization, A second sheet-shaped member made of a second unvulcanized rubber composition that becomes a low-wear rubber having low wear resistance or a second sheet-like member made of a material other than rubber and having a lower wear resistance than the high-wear rubber. The laminated sheet member is formed by laminating any one of the sheet-shaped members 3 with each other.

Next, the laminated sheet member is bent in a zigzag shape, and the surfaces facing each other are brought into close contact to obtain a thick tread member.

When the unvulcanized tread member thus obtained is vulcanized, a layer made of a high wear-resistant rubber and a low wear-resistant rubber layer or a layer made of a material other than rubber are used. Are alternately adjacent rubber tread members (vulcanized) having rubber elasticity.

That is, the tread member can be manufactured very efficiently as compared with the laminating method one by one.

A comparison between the layer made of the high wear-resistant rubber and the low wear-resistant rubber layer or the low wear-resistant layer made of a material other than the rubber shows that the layer made of the material other than the low wear-resistant rubber layer or the rubber is different. The lower wear-resistant layer has a faster wear development rate than the high wear-resistant rubber.

Therefore, when the tread surface is worn by running a pneumatic tire using the tread member as a tread and the tread surface is worn, the low abrasion resistant rubber layer or the low abrasion resistant layer made of a material other than rubber becomes high. It becomes lower than the layer made of the wear-resistant rubber, and a large number of relatively shallow and narrow grooves appear on the tread surface. The grooves that appear in this manner provide drainage and edge effects, and improve the wet performance and on-ice performance of the pneumatic tire.

In addition, since this state can be maintained not only at the beginning of wear but also as wear progresses, wet performance and performance on ice can be continuously improved.

The thickness of the low abrasion resistant rubber layer or the low abrasion resistant layer made of a material other than rubber that appears on the tread surface of the tread due to abrasion is larger than the thickness of the high abrasion resistant rubber layer. It is also preferable that it is thin. If the layer made of the highly wear-resistant rubber is too thick, the water on the ground contact surface will not easily reach the groove, and the drainage property will not be improved and the wet performance and the performance on ice will not be improved. Conversely, if the low abrasion resistant rubber layer or the low abrasion resistant layer made of a material other than rubber becomes too thick, the thickness of the high abrasion resistant rubber layer becomes small, so actual grounding is performed. The area is reduced, and the wet performance and on-ice performance and wear resistance are reduced.

Therefore, the thickness of the layer made of high wear resistant rubber that appears on the tread surface of the tread due to wear and the thickness of the low wear resistant rubber layer or the low wear resistant layer made of a material other than rubber are different. As for the ratio, when the thickness of the layer made of the high wear-resistant rubber is 100, the thickness of the low wear-resistant rubber layer or the low wear-resistant layer made of a material other than rubber is 5 to 40. Is preferred.

Further, when the thickness of the low wear-resistant rubber layer or the low wear-resistant layer made of a material other than rubber which appears on the tread surface of the tread is reduced to less than 0.05 mm, the tread surface is worn. Also makes it difficult for grooves to form on the tread surface,
If the thickness of the layer made of highly wear-resistant rubber is set to 5.0 mm or more, the thickness of the layer made of highly wear-resistant rubber becomes thicker, so that the distance to the groove becomes longer, and the water on the ground contact surface reaches the groove. It is hard to reach and wet performance and performance on ice do not improve.

As a method of making a difference in the wear resistance of rubber, a method of changing the hardness of rubber can be used.
The type of rubber may be changed. As an example, the high wear-resistant rubber is a normal rubber having a foaming rate of 0%, and the low wear-resistant rubber is a foamed rubber.

The low and high abrasion resistance of the rubber may be determined, for example, in accordance with JIS K 6264 by a Lambourn test under standard test conditions (speed 80 m / min, slip rate 30).
%, A load of 40 N, and a falling sand amount of 20 g / min).

The rubber having high wear resistance and the rubber having low wear resistance preferably have a hardness difference of at least 3 degrees (measured at room temperature in accordance with JIS K6301), preferably at least 5 degrees. It is more preferable to provide a hardness difference of

[0027] According to a third aspect of the present invention, there is provided a method for manufacturing a tread member, comprising: an unvulcanized rubber sheet-like member comprising an unvulcanized rubber composition; and a vulcanized material obtained by vulcanizing the unvulcanized rubber composition. A low-strength sheet-like member having a lower strength than the finished rubber composition, and laminating each other to form a laminated sheet member,
Bending the laminated sheet member in a zigzag shape, and bringing the opposing surfaces into close contact with each other to form a thick tread member.

Next, the operation of the method for manufacturing a tread member according to the third aspect will be described. First, in the first step, an unvulcanized rubber sheet-like member made of an unvulcanized rubber composition, and a lower strength than a vulcanized rubber composition obtained by vulcanizing the unvulcanized rubber composition. The low-strength sheet-shaped member and the low-strength sheet-shaped member are bonded to each other to form a laminated sheet member.

Next, when the laminated sheet member is bent in a zigzag shape and the surfaces facing each other are brought into close contact with each other, a thick tread member can be easily obtained.

When this thick tread member is vulcanized,
The laminated sheet member is a thick tread in which the unvulcanized rubber sheet members are in close contact with each other, the low-strength sheet members are in close contact with each other, and the unvulcanized rubber sheet members and the low-strength sheet members are alternately adjacent to each other. A member is formed.

When the thus obtained unvulcanized tread member is vulcanized, a layer composed of a vulcanized rubber composition,
A layer made of a low-strength sheet-shaped member is a tread member having rubber elasticity (vulcanized) that is alternately adjacent.

That is, the tread member can be manufactured very efficiently as compared with the lamination method one by one.

When the tread made of the tread member is deformed, the layer made of the low-strength sheet-like member is peeled off from the rubber layer, or the layer itself made of the low-strength sheet-like member is destroyed. Is formed between them.

The term "low strength" as used herein means that at least one strength such as bending, tension, compression, and shearing is low.

By the grooves thus formed, drainage and edge effects are obtained, and the wet performance and the performance on ice of the pneumatic tire are improved.

According to a fourth aspect of the present invention, there is provided a method for manufacturing a tread member, wherein an unvulcanized rubber sheet member made of an unvulcanized rubber composition and a soluble sheet member made of a material soluble in a liquid are bonded to each other. And forming a laminated sheet member in a zigzag manner and bringing the opposing surfaces into close contact with each other to form a thick tread member.

Next, the operation of the method for manufacturing a tread member according to the fourth aspect will be described. First, in the first step, an unvulcanized rubber sheet-shaped member made of an unvulcanized rubber composition, and a soluble sheet-shaped member made of a material that is dissolved by a liquid,
Are laminated to each other to form a laminated sheet member.

Next, when the laminated sheet member is bent in a zigzag shape and the surfaces facing each other are brought into close contact with each other, a thick tread member can be easily obtained.

When this thick tread member is vulcanized,
The laminated sheet member is a thick tread in which the unvulcanized rubber sheet members are in close contact with each other, the soluble sheet members are in close contact with each other, and the unvulcanized rubber sheet members and the soluble sheet members are alternately adjacent to each other. A member is formed.

When the thus obtained unvulcanized tread member is vulcanized, a layer made of a vulcanized rubber composition (ie, a rubber layer) and a layer made of a soluble sheet-like member (hereinafter, referred to as a layer) are formed.
And a tread member having rubber elasticity (vulcanized) adjacent to each other alternately.

That is, the tread member can be manufactured extremely efficiently as compared with the laminating method one by one.

When a liquid is applied to the tread member, the dissolving layer is dissolved by the applied liquid, and a groove is formed between the rubber layers.

For example, if the dissolving layer is formed of a material that dissolves in water, the dissolving layer is dissolved by water on the road surface.
When traveling on a wet road surface or an ice road surface, grooves can be formed by water, and high wet performance and on-ice performance can be obtained from the beginning of traveling, and high wet performance and on-ice performance can be continuously obtained until the end of wear.

After the manufacture of the tire, a groove can be formed from the beginning by applying a liquid to the tread to dissolve the dissolving layer.

The liquid may be other than water as long as it can dissolve the dissolving layer, and the dissolving layer may also be made of a material soluble in liquid other than water.

The dissolving layer may be a fiber layer made of water-soluble fibers. When the dissolving layer is a fiber layer made of water-soluble fibers, it easily absorbs moisture and dissolves quickly.

Further, it is preferable that the thickness of the dissolving layer appearing on the ground contact surface of the tread is smaller than the thickness of the rubber layer. If the rubber layer is too thick, it becomes difficult for water on the ground surface to reach the groove, and the drainage performance is not improved, and the wet performance and the performance on ice are not improved. Conversely, if the melted layer is too thick, the actual thickness of the rubber layer is reduced, so that the actual contact area is reduced, and the wet performance, on-ice performance, and wear resistance are reduced.

Therefore, the ratio of the thickness of the rubber layer appearing on the ground contact surface of the tread to the thickness of the dissolving layer is such that when the thickness of the rubber layer is 100, the thickness of the dissolving layer is 5 to 40. preferable.

When the thickness of the rubber layer is set to 5.0 mm or more, the distance to the groove becomes long because the thickness of the rubber layer is large.
Water on the ground contact surface does not easily reach the groove, and wet performance and performance on ice are not improved.

Further, when the tread member manufactured by the present invention is used, the groove can be set to a desired width only by setting the thickness of the dissolving layer without using a blade, that is, by setting the thickness of the dissolvable sheet member. it can. That is, by using a dissolvable sheet-like member much thinner than a blade, a groove narrower than before can be easily formed without causing a problem in tire production, and a decrease in the ground contact area is suppressed. be able to.

Here, conventionally, when a plurality of sipes (the groove depth is deep so as not to disappear until the end of wear) are formed in the land portion of the block or the like, the rigidity in the block is biased and the ground pressure in the block is reduced. Are uneven, thereby causing uneven wear, and problems such as uneven wear occurring in each small block due to the small block divided by the sipe falling down when touching the ground. On the other hand, if the tread member manufactured by the present invention is used, a relatively shallow groove can be formed,
The occurrence of unevenness in rigidity in the block can be suppressed, and the falling of the small block between the grooves can be suppressed, so that the occurrence of the above-described uneven wear can be suppressed.

According to a fifth aspect of the present invention, in the method for manufacturing a tread member according to any one of the first to fourth aspects, the opening shape of the inlet is a slit shape extending linearly, and the opening shape of the outlet is provided. The shape is a slit shape bent in a zigzag, using a guide having a slit hole that gradually changes from linear to zigzag from the inlet to the outlet from the inlet, the laminated sheet member of the slit hole It is characterized in that the laminated sheet member is bent in a zigzag shape by inserting from the inlet and pulling out from the outlet.

Next, the operation of the method for manufacturing a tread member according to the fifth aspect will be described. When the laminated sheet member is inserted from the entrance of the slit hole and pulled out from the exit, the laminated sheet member is gradually bent in a zigzag shape in the slit hole, becomes a zigzag shape, and is pulled out from the exit.

According to a sixth aspect of the present invention, in the method for manufacturing a tread member according to any one of the first to fourth aspects, a plurality of first bent portions extending in one direction and arranged in parallel with each other. A plurality of projections, which extend in the same direction as the first folding projections and are arranged in parallel with each other, and are arranged out of phase with the first folding projections in the direction in which the first folding projections are arranged. 2 bent projections,
Using, the laminated sheet member is disposed between the first bent protrusion and the second bent protrusion, and then the first bent protrusion and the second bent protrusion are brought closer to each other, The distance between each of the first bent protrusions and the distance between each of the second bent protrusions are narrowed, and the laminated sheet member is bent in a zigzag shape.

Next, the operation of the method for manufacturing a tread member according to claim 6 will be described. A laminated sheet member is disposed between the first and second fold projections, after which the first and second fold projections are brought closer together and each of the first fold projections is disposed. When the spacing and the spacing between the second bending protrusions are reduced, the laminated sheet member is bent in a zigzag shape.

According to a seventh aspect of the present invention, in the method for manufacturing a tread member according to any one of the first to fourth aspects, the first rotating roller whose width gradually narrows outward in the radial direction. A first roller member arranged at intervals in one direction, and a first roller arranged in the same direction as the first rotating roller, and the first rotating roller arranged in a direction in which the first rotating roller is arranged. And a plurality of second rotating rollers arranged at a predetermined interval from the first rotating roller and forming a zigzag gap with the plurality of first rotating rollers. And a second roller member having the rotary roller of (1), wherein the laminated sheet member is bent in a zigzag shape by passing the laminated sheet member through the zigzag-shaped gap.

Next, the operation of the method for manufacturing a tread member according to claim 7 will be described. When passing the laminated sheet member through a zigzag gap between the first rotating roller of the first roller member and the second rotating roller of the second roller member,
The laminated sheet member is bent in a zigzag shape. Also,
Since the first rotating roller and the second rotating roller can rotate with the passage of the laminated sheet member, the laminated sheet member can easily pass through the zigzag gap.

[0058] The method for manufacturing a pneumatic tire according to claim 8 is a method for manufacturing a tread member obtained by the method for manufacturing a tread member according to any one of claims 1 to 7.
It is characterized in that a pneumatic tire is manufactured by sticking it to the crown portion of an uncured carcass together with the reinforcing layer and vulcanizing the carcass.

Next, the operation of the method for manufacturing a pneumatic tire according to claim 8 will be described. In the method for manufacturing a pneumatic tire according to claim 8, the tread member obtained by the method for manufacturing a tread member according to any one of claims 1 to 7 is used as a reinforcing layer (for example, a belt or the like). At the same time, a pneumatic tire having high wet performance and high performance on ice can be obtained by attaching it to a crown portion of an unvulcanized carcass, loading it into a predetermined mold, and performing vulcanization.

[0060]

BEST MODE FOR CARRYING OUT THE INVENTION

[First Embodiment] A first embodiment of the present invention will be described with reference to FIGS.

The pneumatic tire 10 of the present embodiment has a radial pneumatic tire in which a belt and a tread as a reinforcing layer are sequentially arranged on the outer periphery of a crown portion of a carcass straddling a toroid between a pair of bead cores. It is. The internal structure other than the tread is not different from the structure of a general radial tire, and therefore the description is omitted.

As shown in FIG. 1, a plurality of blocks 18 are formed in the tread 12 by a plurality of circumferential grooves 14 and a plurality of lateral grooves 16 intersecting the circumferential grooves 14.

The tread 12 is composed of an upper cap portion 12A directly in contact with the road surface and a lower base portion 12B disposed adjacent to the inside of the tire of the cap portion 12A. It has a structure.

As shown in FIG. 2, the cap portion 12A
Rubber layer 20 having low wear resistance and rubber layer 22 having high wear resistance
Are alternately stacked in the tire width direction (the direction of the arrow W).

Next, an apparatus for manufacturing a tread member used for the cap portion 12A will be described.

FIG. 3 shows a first sheet-like member 24 made of a first unvulcanized rubber composition which becomes a highly wear-resistant rubber by vulcanization, and a high wear-resistant rubber which is vulcanized. A guide that bends a laminated sheet member 28 obtained by laminating a second sheet member 26 made of a second unvulcanized rubber composition that becomes a low wear-resistant rubber having lower wear resistance than a zigzag shape. 30 is shown.

The guide 30 is formed by, for example, bending a metal plate or the like. The opening of the inlet 32A has a slit shape extending straight, and the opening of the outlet 32B has a slit shape bent zigzag. And a slit hole 32 whose cross-sectional shape gradually changes from linear to zigzag as going from the inlet 32A to the outlet 32B. In addition, the width of the guide 30 is
It gradually decreases from A to the exit 32B.

In the vicinity of the outlet 32B of the guide 30,
A molding roll 34 is provided. Molding roll 34
Is composed of an upper roll 36 having a constant diameter and a lower roll 38 having a small diameter portion 38A having a constant length in the center and having a constant diameter, and is rotated in the direction of arrow A by a motor (not shown) or the like.

Next, a procedure for manufacturing a tread member used for the cap portion 12A will be described.

First, a first sheet-like member 24 made of a first unvulcanized rubber composition which becomes a highly wear-resistant rubber by being vulcanized, and which is more vulcanized than a highly wear-resistant rubber. A second sheet-like member 26 made of a second unvulcanized rubber composition that becomes a low-wear rubber with low abrasion is attached to obtain a laminated sheet member 28 as shown in FIG.

Next, the laminated sheet member 28 is
0 is inserted from the entrance 32A of the slit hole 32 and the exit 32 is inserted.
Pull out from B. The laminated sheet member 28 has a slit hole 3
2, gradually bends in a zigzag shape, becomes a zigzag shape, and is pulled out from the outlet 32B.

Thereafter, the laminated sheet member 28 bent in a zigzag shape is rotated by the upper roll 36 and the lower roll 3.
8 and the small-diameter portion 38A, the surfaces facing each other adhere to each other, and a thick tread member 40 having a constant thickness is obtained as shown in FIGS.

The long tread member 40 can be continuously obtained by sequentially passing the long laminated sheet member 28 through the guide 30 and the molding roll 34.

The long tread member 40 obtained in this manner is connected to a reinforcing layer (for example, a belt, etc.)
By sticking to a crown portion of an unvulcanized carcass together with a band-shaped unvulcanized rubber member serving as a base portion 12B to form a green tire, and loading this in a mold to perform vulcanization,
As shown in FIG. 5, the cap portion 12A in which the low-wear rubber layers 20 and the high-wear rubber layers 22 are alternately laminated in the tire width direction is obtained. Since the cap portion 12A formed in this manner has only the rubber layer 20 with low wear resistance on the tread surface, for example, the tread surface is buffed to the position indicated by the imaginary line S in FIG. Equalizing or running is performed, and a portion where the low wear-resistant rubber layer 20 and the high wear-resistant rubber layer 22 are alternately laminated on the tread surface appears.

When the surface of the tread 12 is worn by running, the rubber layer 20 having low wear resistance develops more than the rubber layer 22 having high wear resistance. As shown in FIG. The portion of the rubber layer 20 having low wear resistance is lower than the portion of the rubber layer 22 having a higher thickness, and a large number of narrow grooves 26 having a relatively shallow depth appear on the surface of the tread 12. The grooves 26 appearing in this manner have a shape extending along the tire circumferential direction, and the grooves 26 appearing plurally provide drainage, thereby improving wet performance and performance on ice.

Since this state can be maintained not only at the beginning of wear but also as wear progresses, wet performance and performance on ice can be continuously improved. Further, since the coefficient of friction in the lateral direction is improved, a side slip effect at the time of cornering can be obtained.

A first sheet-like member made of a first unvulcanized rubber composition which becomes a normal unfoamed rubber by vulcanization, and a second sheet material which becomes a foamed rubber by vulcanization A second sheet member made of an unvulcanized rubber composition may be used, and a laminated sheet member obtained by laminating them may be bent in a zigzag shape to form a tread member.
The second unvulcanized rubber composition contains a foaming agent (and a foaming aid) as is well known in addition to the usual rubber composition, and when vulcanized, gas is generated in the rubber. As a result, a foamed rubber having countless closed cells is obtained. When this tread member is vulcanized, a tread member having a structure in which a normal rubber layer made of unfoamed rubber and a foamed rubber layer made of foamed rubber are alternately laminated is obtained. Since the foamed rubber has a lower abrasion resistance than the non-foamed rubber, when the tread is worn by running, the foamed rubber layer becomes lower than the non-foamed rubber layer, and a groove is formed.

In the above embodiment, the first sheet-like member 24 made of the first unvulcanized rubber composition which becomes a highly wear-resistant rubber by vulcanization, and the high wear resistance is obtained by vulcanization The tread member 40 is formed using a laminated sheet member 28 in which a second sheet member 26 made of a second unvulcanized rubber composition, which is a low wear-resistant rubber having lower wear resistance than the conductive rubber, is bonded. However, the present invention is not limited to this. The third sheet-shaped member made of a material other than rubber and having lower wear resistance than the rubber layer 22 having high wear resistance, and the first sheet-shaped member 24 are used. The tread member 40 may be formed by using the laminated sheet members 28 bonded to each other.

In some cases, the laminated sheet member 28 may be formed by laminating three or more layers having different wear resistance.

Further, an unvulcanized rubber sheet-like member made of the unvulcanized rubber composition, and a low-strength low-strength material lower than the vulcanized rubber composition obtained by vulcanizing the unvulcanized rubber composition Using a sheet-like member, a laminated sheet member obtained by laminating these may be folded in a zigzag shape to form a tread member. When a pneumatic tire provided with a tread made of this tread member is run (or may be rotated by being pressed against a rotating drum whose surface is appropriately roughened), the tread is repeatedly deformed. When the tread is repeatedly deformed, the layer made of the low-strength sheet-like member is broken and peels off from the tread side, so that the layer made of the low-strength sheet-like member becomes lower than the rubber layer, and a groove is formed.

As the low-strength sheet-like member having lower strength than the rubber of the rubber layer, for example, a nonwoven fabric is preferable. In this case, a laminated sheet member obtained by laminating a sheet member made of an unvulcanized rubber composition and a nonwoven fabric is bent into a zigzag shape to form a tread member.

The nonwoven fabric preferably has a small anisotropy with respect to tension, compression, shearing, and the like. Examples of the material of the filament fibers constituting the nonwoven fabric include natural polymer fibers such as cotton, rayon, and cellulose; synthetic polymer fibers such as aliphatic polyamide, polyester, polyvinyl alcohol, polyimide, and aromatic polyamide; and carbon fibers and glass fibers. One or more types of fibers selected from steel wires can be mixed, but fibers of other materials may be used.

The diameter or the maximum diameter of the fiber applied to the non-woven fabric is preferably in the range of 0.1 to 100 μm, and the cross-sectional shape should be circular, cross-sectional shape different from a circle, or having a hollow portion. Can be done. Furthermore, a core-sheath structure in which different materials are arranged in an inner layer and an outer layer, or a composite fiber having a U-shaped, petal-shaped, or layered shape can also be used.

The length of the fiber used for the nonwoven fabric is 8
mm or more is preferable. When the tread has a nonwoven fabric layer, the thickness of the nonwoven fabric layer in the portion where the rubber layer and the nonwoven fabric layer are alternately laminated is preferably 0.05 mm to 2.0 mm. Therefore, the thickness of the nonwoven fabric used for the laminated sheet member is preferably in the range of 0.025 to 1.0 mm (the thickness of the nonwoven fabric was measured under a pressure of 20 g / cm ² ).
Weight per ² ) is preferably in the range of 5 to 150 g.

As the fiber itself, a fiber having a two-layer structure in which the inner layer and the outer layer are made of different materials can be used as the material of the nonwoven fabric.

The low-strength sheet-like member may be other than a non-woven fabric. Specific examples include paper (including cardboard) and the like, but other materials may be used.

A laminated sheet member obtained by laminating an unvulcanized rubber sheet member made of an unvulcanized rubber composition and a soluble sheet member made of a material soluble in liquid is used. May be bent in a zigzag shape to form a tread member. A tread formed using this tread member has a portion in which a rubber layer and a layer made of a dissolvable sheet member (hereinafter, referred to as a dissolution layer) are alternately laminated.

When a liquid is applied to the dissolving layer, the dissolving layer is dissolved by the applied liquid, and a groove is formed between the rubber layers. According to the present invention, the dissolved layer can be completely removed.

When the dissolving layer is formed of a dissolvable sheet-like member made of a material that dissolves in water, the dissolving layer is dissolved by the water on the road surface, so that the groove is formed by the water when traveling on a wet road surface or an icy road surface. Can be.

The liquid may be other than water as long as it can dissolve the dissolving layer, and the dissolving layer may also be made of a material soluble in liquids other than water.

Note that a soluble sheet member made of water-soluble fibers may be used. When the dissolving layer is a fibrous layer made of water-soluble fibers, it easily absorbs moisture and dissolves quickly.

As a specific example of the dissolvable sheet member, a non-woven fabric made of a water-soluble fiber can be used.

The water-soluble fiber has a vinyl alcohol unit of 50 mol% or more and an average degree of polymerization of 100 to 300.
Polyvinyl alcohol-based polymer having a saponification degree of less than 80% is used as a raw material.
Fiber that has not been subjected to a treatment for imparting water resistance such as acetalization can be used.

As units other than the vinyl alcohol unit and the vinyl acetate unit, units that inhibit the crystallinity of polyvinyl alcohol such as ethylene, allyl alcohol, itaconic acid, acrylic acid, and maleic anhydride are preferable.

Next, a method for producing a water-soluble fiber will be briefly described. First, 75 mol% of vinyl alcohol units,
A dimethyl sulfoxide (DMSO) is mixed with a polyvinyl alcohol-based polymer having an average degree of polymerization of 25 mol% of a vinyl acetate unit of 500 and a saponification degree of 75 mol%, and after the replacement with nitrogen, sufficiently defoaming under reduced pressure. Perform to make a 45% dimethyl sulfoxide (DMSO) solution.

Next, this spinning stock solution is wet-spun from a single-hole nozzle having a diameter of 0.15 mm into a mixed solution of acetone / DMSO (weight ratio: 85/15) at 2 ° C.

Thereafter, acetone / DMSO (weight ratio: 9)
After stretching 4.5 times in the mixed solution of (5/5), DMSO is sufficiently removed in acetone and dried at 80 ° C. to obtain a polyvinyl alcohol fiber. The polyvinyl alcohol fiber is soluble in water at 10 ° C.

The dissolvable sheet-like member may be other than a non-woven fabric made of water-soluble fibers. Examples of the dissolvable sheet-like member include a film-shaped water-soluble fiber material and an oblate. Other than these may be used. [Second Embodiment] A second embodiment of the present invention will be described with reference to FIG.

FIG. 7 shows a roller guide 42 according to a second embodiment for bending the laminated sheet member 28 in a zigzag shape.

The roller type guide 42 is provided with the upper roller 4
4 and a lower roller 46, and is rotated in the direction of arrow B by a motor (not shown) or the like.

The upper roller 44 and the lower roller 46 are provided with a plurality of abacus ball-shaped forming rollers 48, each of which has a smaller width toward the outside in the radial direction, at regular intervals. The molding rollers 48 of the upper roller 44 and the molding rollers 48 of the lower roller 46 are alternately arranged, and a zigzag gap is formed between the upper roller 44 and the lower roller 46.

The upper roller 4 for rotating the laminated sheet member 28
When the laminated sheet member 28 is drawn out while passing between the lower roller 4 and the lower roller 46, the laminated sheet member 28 has a zigzag shape.

Then, the laminated sheet member 28 folded in a zigzag shape is passed between the small diameter portion 38A of the upper roll 36 and the lower roll 38 which rotate in the same manner as in the first embodiment described above, whereby the tread member is formed. 40 are obtained. Third Embodiment A third embodiment of the present invention will be described with reference to FIGS.

FIG. 8 shows a bending device 50 according to a third embodiment for bending the laminated sheet member 28 in a zigzag shape.

The bending device 50 includes an upper die 54 and a lower die 56 which are arranged so as to face each other, and which can be moved by a pair of cylinders 52 toward and away from each other.

The lower mold 56 has a rectangular base 60 connected to the piston rod 58 of the cylinder 52. The inside of the base 60 is formed hollow, and a plurality of molding members 62 having a tapered cross section are arranged in parallel with each other.

As shown in FIGS. 9A and 9B, the molding member 62 is slidable along a slide shaft 64 fixed to the base 60, and a feed screw 68 rotated by a motor 66. Is screwed into.

As shown in FIGS. 9 (A) and 9 (B), a motor 66 and a feed screw 68 respectively correspond to each molding member 62, and can be moved independently. . The other molding member 62 that does not move with the predetermined feed screw 68 is provided with a relief hole 70 so as not to interfere with the feed screw 68.

The upper mold 54 also has a molding member 62 similarly to the lower mold 56, but the molding member 62 of the upper mold 54 is provided.
And the molding members 62 of the lower mold 56 are different from each other only in that they are arranged alternately, and the moving mechanism of the molding members 62 is the same.

In the present embodiment, the laminated sheet member 28 is disposed between the upper mold 54 and the lower mold 56, and the molding member 62 of the upper mold 54 and the molding of the lower mold 56, as shown by arrows in FIG. When the members 62 are moved closer to each other and the distance between the molding members 62 is reduced, the laminated sheet member 28 has a zigzag shape as shown in FIG.

Thereafter, the laminated sheet member 28 folded in a zigzag shape is passed between the small diameter portion 38A of the upper roll 36 and the lower roll 38, which rotate in the same manner as in the first embodiment described above, thereby forming a tread member. 40 are obtained.

[0112]

As described above, according to the method for manufacturing a tread member of the present invention, an excellent effect that a tread member used for a tread having a laminated structure of layers having different properties can be manufactured extremely efficiently. Having.

According to the method for manufacturing a tread member according to claims 2 to 4, an excellent effect that a tread member used for a pneumatic tire having excellent wet performance and ice performance can be manufactured extremely efficiently. Have.

Further, the pneumatic tire manufacturing method of the present invention has an excellent effect that a pneumatic tire having a tread having a laminated structure of layers having different properties can be efficiently manufactured.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a tread of a pneumatic tire manufactured by a method for manufacturing a pneumatic tire according to the present invention.

FIG. 2 is an enlarged cross-sectional view of the tread shown in FIG. 1 along a tire width direction.

FIG. 3 is a perspective view of an apparatus for forming a tread member by bending a laminated sheet member in a zigzag shape.

FIG. 4 is an enlarged sectional view of an unvulcanized tread member.

FIG. 5 is an enlarged sectional view of a tread after vulcanization.

FIG. 6 is an enlarged sectional view of the tread after abrasion.

FIG. 7 is a perspective view of a roller guide.

FIG. 8 is a perspective view of a bending device.

FIG. 9 (A) is the lower mold 9 (A) -9 (A) shown in FIG.
FIG. 9B is a sectional view taken along the line, and FIG.
It is a 9 (B) line sectional view.

FIG. 10 is a front view of the folding device showing a state before folding of the laminated sheet member.

FIG. 11 is a front view of the folding device showing a state after the folding of the laminated sheet member.

[Explanation of symbols]

Reference Signs List 12 tread 20 rubber layer (low-wear rubber) 22 rubber layer (high-wear rubber, vulcanized rubber composition) 24 first sheet member (unvulcanized rubber sheet member) 26 second sheet Shaped member 28 Laminated sheet member 30 Guide 32 Slit hole 40 Tread member 44 Upper roller (first roller member) 46 Lower roller (second roller member) 48 Molding roller (first rotating roller, first rotating roller) 62 Molding Member (first bent protrusion, second bent protrusion)

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI B29K 105: 24 B29L 30:00

Claims (8)

[Claims] 1. A step of forming a laminated sheet member by laminating a plurality of types of sheet members having different properties from each other, folding the laminated sheet member in a zigzag shape, and bringing the opposing surfaces into close contact with each other to form a thick tread member. And a method for producing a tread member. 2. A first sheet-like member made of a first unvulcanized rubber composition which becomes a highly wear-resistant rubber by vulcanization, and a first sheet-like member which is more vulcanized than the highly wear-resistant rubber. A second sheet-like member made of a second unvulcanized rubber composition that becomes a low-wear rubber having low wear resistance or a third material made of a material other than rubber and having lower wear resistance than the high-wear rubber. A step of forming a laminated sheet member by laminating any one of the sheet-shaped members to each other, bending the laminated sheet member in a zigzag shape, and bringing the opposing surfaces into close contact with each other to form a thick tread member, A method for manufacturing a tread member, comprising: 3. An unvulcanized rubber sheet-like member comprising an unvulcanized rubber composition, and a low-strength material having a lower strength than a vulcanized rubber composition obtained by vulcanizing the unvulcanized rubber composition. A step of forming a laminated sheet member by laminating the sheet-like members with each other, and a step of bending the laminated sheet member in a zigzag shape, and bringing the opposing surfaces into close contact to form a thick tread member. Manufacturing method of a tread member. 4. A step of laminating an unvulcanized rubber sheet member made of an unvulcanized rubber composition and a soluble sheet member made of a material soluble in a liquid to form a laminated sheet member, Bending the laminated sheet member in a zigzag shape, and bringing the opposing surfaces into close contact to form a thick tread member. 5. The opening of the inlet has a slit shape extending straight, and the opening of the outlet has a slit shape bent in a zigzag shape, and the cross-sectional shape of the hole changes from a straight line to a zigzag shape from the inlet to the outlet. 4. The laminated sheet member is bent in a zigzag manner by inserting a laminated sheet member from an entrance of the slit hole and pulling out the laminated sheet member from an exit using a guide having a slit hole that changes gradually. Item 5. The method for manufacturing a tread member according to any one of items 4. 6. A plurality of first bent protrusions extending in one direction and arranged in parallel with each other, and a plurality of first bent protrusions extending in the same direction as the first bent protrusions and arranged in parallel with each other. A plurality of second folding protrusions arranged in a phase-shifted manner with respect to the first folding protrusions; Then, the first bent protrusion and the second bent protrusion are brought closer to each other, and the distance between each of the first bent protrusions and the distance between each of the second bent protrusions are adjusted. The method for manufacturing a tread member according to claim 1, wherein the tread member is narrowed and bent in a zigzag shape. 7. A first roller member in which a first rotating roller whose width gradually narrows toward the outside in the radial direction is arranged at an interval in one direction, and an interval in the same direction as the first rotating roller is provided. The first rotating roller is arranged so as to be out of phase with the first rotating roller in the direction in which the first rotating roller is arranged.
A second roller member having a plurality of second rotating rollers that are arranged at a fixed interval from the rotating rollers and form a zigzag gap between the plurality of first rotating rollers;
The tread member according to any one of claims 1 to 4, wherein the laminated sheet member is bent in a zigzag shape by passing the laminated sheet member through the zigzag-shaped gap. Production method. 8. A vulcanization method in which a tread member obtained by the method for manufacturing a tread member according to claim 1 is pasted together with a reinforcing layer to a crown portion of an uncured carcass. And producing a pneumatic tire.