JP2014213506A - Tread forming method and precured tread for tire - Google Patents

Tread forming method and precured tread for tire Download PDF

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JP2014213506A
JP2014213506A JP2013091616A JP2013091616A JP2014213506A JP 2014213506 A JP2014213506 A JP 2014213506A JP 2013091616 A JP2013091616 A JP 2013091616A JP 2013091616 A JP2013091616 A JP 2013091616A JP 2014213506 A JP2014213506 A JP 2014213506A
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tread
sheet
side wall
tire
forming
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秀之 金田
Hideyuki Kaneda
秀之 金田
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Bridgestone Corp
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Bridgestone Corp
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    • BPERFORMING OPERATIONS; TRANSPORTING
    • B29WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29DPRODUCING PARTICULAR ARTICLES FROM PLASTICS OR FROM SUBSTANCES IN A PLASTIC STATE
    • B29D30/00Producing pneumatic or solid tyres or parts thereof
    • B29D30/06Pneumatic tyres or parts thereof (e.g. produced by casting, moulding, compression moulding, injection moulding, centrifugal casting)
    • B29D30/52Unvulcanised treads, e.g. on used tyres; Retreading
    • B29D30/54Retreading
    • B29D30/56Retreading with prevulcanised tread
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B60VEHICLES IN GENERAL
    • B60CVEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
    • B60C11/00Tyre tread bands; Tread patterns; Anti-skid inserts
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B60VEHICLES IN GENERAL
    • B60CVEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
    • B60C11/00Tyre tread bands; Tread patterns; Anti-skid inserts
    • B60C11/02Replaceable treads

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Tyre Moulding (AREA)
  • Tires In General (AREA)

Abstract

PROBLEM TO BE SOLVED: To provide a tread forming method capable of effectively and easily suppressing generation of bare at the time of forming a tread.SOLUTION: A tread forming method includes a tread molding step of vulcanizing unvulcanized rubber in a metal mold to form a tread. In the tread molding step, vulcanization molding is carried out in a state in which a sheet member having communication holes in a thickness direction and communication holes extending in an extension direction crossing the communication holes in the thickness direction is disposed between a tread formed part of unvulcanized rubber in which the tread is formed and a tread forming part abutting on the tread formed part out of an inner surface of the metal mold. On a surface layer of the tread formed, a surface layer including the sheet member is formed.

Description

本発明は、タイヤトレッドを形成する際にベアの発生を効果的かつ簡便に抑制することのできる方法、及び、その方法を用いてトレッドを形成したタイヤ用プレキュアトレッドに関する。   The present invention relates to a method capable of effectively and simply suppressing the occurrence of bears when forming a tire tread, and a tire precure tread in which a tread is formed using the method.

一般に、未加硫の生タイヤや帯状ゴム部材を金型内で加硫成型してタイヤやタイヤ用プレキュアトレッドを形成する際には、金型内での空気の残留等に起因したゴム流れの不良により型付けが十分になされず、ベアが発生することがある。そして、特に、トレッドの表面、具体的にはサイプや溝等を配設した陸部のエッジ部分にベアが発生すると、外観品質として好ましくないだけでなく、エッジ成分が減少して所期の性能を有するタイヤが得られなくなる場合がある。そこで、ベアの発生を抑制する手法として、例えば、空気排出用のスリットベントを設けた加硫金型を使用し、加硫成型時にスリットベントを介して金型内から空気を十分に排出することによりベアの発生を抑制する方法(例えば、特許文献1参照)が提案されている。   Generally, when an unvulcanized raw tire or a belt-shaped rubber member is vulcanized and molded in a mold to form a tire or a tire precured tread, the rubber flow caused by air remaining in the mold Due to this defect, the molding may not be sufficiently performed and a bear may occur. In particular, when bears occur on the tread surface, specifically on the edge portion of the land where sipes, grooves, etc. are provided, not only is the appearance quality unfavorable, but the edge component is reduced and the expected performance is achieved. In some cases, tires having the above cannot be obtained. Therefore, as a technique for suppressing the generation of bears, for example, a vulcanization mold provided with a slit vent for air discharge is used, and air is sufficiently discharged from the mold through the slit vent during vulcanization molding. Has proposed a method for suppressing the generation of bears (see, for example, Patent Document 1).

特開2005−305921号公報JP 2005-305921 A

しかしながら、上記の方法では、金型の加工に要する費用が高くなると共に、ベアの発生を十分に抑制することができなかった。このような状況に鑑みて、タイヤやタイヤ用プレキュアトレッドのトレッド形成時に加硫金型から効率的に空気を排出し、ベアの発生を効果的かつ簡便に抑制することのできる技術が求められていた。   However, in the above method, the cost required for processing the mold is increased, and generation of bears cannot be sufficiently suppressed. In view of such circumstances, there is a need for a technology that can efficiently and easily suppress the generation of bears by efficiently discharging air from a vulcanization mold when forming a tread of a tire or a tire pre-cured tread. It was.

そこで、本発明の目的は、トレッド形成時のベアの発生を効果的かつ簡便に抑制することのできるトレッドの形成方法を提供することにある。   Therefore, an object of the present invention is to provide a method for forming a tread that can effectively and easily suppress the generation of bears during tread formation.

即ち、本発明に係るトレッドの形成方法は、未加硫ゴムを金型内で加硫成型してトレッドを形成するトレッド成形工程において、トレッドが形成される未加硫ゴムのトレッド被形成部と、金型の内表面のうちトレッド被形成部に当接するトレッド形成部との間に、厚さ方向の連通孔及び該厚さ方向の連通孔と交差して延びる延在方向の連通孔を有するシート状部材を設置した状態で加硫成型を行うことを特徴とする。この形成方法によれば、加硫成型時に、シート状部材の前記連通孔を介してトレッド被形成部とトレッド形成部との間から空気を効率的に排出することができるため、トレッドにベアが発生することを効果的かつ簡便に抑制することができる。   That is, the method for forming a tread according to the present invention includes a tread formation portion of an unvulcanized rubber in which a tread is formed in a tread forming step of forming a tread by vulcanizing and molding an unvulcanized rubber in a mold. In addition, a communication hole in the thickness direction and a communication hole in the extending direction extending across the communication hole in the thickness direction are provided between the inner surface of the mold and the tread formation portion that contacts the tread formation portion. The vulcanization molding is performed with the sheet-like member installed. According to this forming method, at the time of vulcanization molding, air can be efficiently discharged from between the tread forming portion and the tread forming portion through the communication hole of the sheet-like member, so that bears are formed on the tread. Generation | occurrence | production can be suppressed effectively and simply.

ここで、本発明に係るトレッドの形成方法において、シート状部材の厚さが、0.1〜3mmであることが好ましい。該範囲の厚さのシート状部材を使用することでより効果的にベアの発生を抑制することができるためである。また、シート状部材の厚さは、0.1〜0.8mmであることが更に好ましい。生産性、タイヤ性能及びタイヤの外観を損なうことなく、ベアの発生を抑制することができるためである。   Here, in the tread forming method according to the present invention, the thickness of the sheet-like member is preferably 0.1 to 3 mm. This is because the generation of bears can be more effectively suppressed by using a sheet-like member having a thickness in this range. Further, the thickness of the sheet-like member is more preferably 0.1 to 0.8 mm. This is because the occurrence of bears can be suppressed without impairing productivity, tire performance, and tire appearance.

本発明に係るトレッドの形成方法の一例では、トレッドが、溝と、溝により区画形成された陸部とを含み、トレッド被形成部が、溝の溝底が形成される溝底被形成部と、陸部の側壁面が形成される側壁面被形成部と、陸部の踏面が形成される踏面被形成部とを備えている。
そして、この一例の形成方法では、シート状部材を、側壁面被形成部及び踏面被形成部の範囲内であって、少なくとも側壁面被形成部と踏面被形成部との境界線上を覆う位置に設置することにより、ベアの発生を抑制しつつ、この形成方法を用いて形成したトレッドを有するタイヤの走行時に溝底に亀裂が生じることを防ぐことができる。
また、この一例の形成方法では、表面層を、側壁面及び踏面の範囲内であって、少なくとも側壁面と踏面との境界線上を覆う位置に形成することにより、ベアの発生を抑制しつつ、この形成方法を用いて形成したトレッドを有するタイヤの走行時に溝底に亀裂が生じることを防ぐことができる。
In an example of the tread formation method according to the present invention, the tread includes a groove and a land portion defined by the groove, and the tread formation portion is a groove bottom formation portion in which the groove bottom of the groove is formed. And a side wall surface forming portion where a land portion side wall surface is formed, and a tread surface forming portion where a land surface tread is formed.
In this example of the forming method, the sheet-like member is within the range of the side wall surface formed portion and the tread surface formed portion, and at a position covering at least the boundary line between the side wall surface formed portion and the tread surface formed portion. By installing it, it is possible to prevent the occurrence of cracks in the groove bottom during running of a tire having a tread formed using this forming method, while suppressing the generation of bears.
Further, in this example of the forming method, the surface layer is formed within a range of the side wall surface and the tread surface, and at a position covering at least the boundary line between the side wall surface and the tread surface, thereby suppressing the occurrence of bears, It is possible to prevent a crack from occurring at the groove bottom during running of a tire having a tread formed by using this forming method.

そして、本発明に係るトレッドの形成方法では、シート状部材は、熱可塑性樹脂からなることが好ましい。熱可塑性樹脂は、加硫成型時に形態を柔軟に変化させることができ、また、熱硬化性樹脂とは異なり、加硫成型時に分子構造が大幅に変化することがないからである。また、シート状部材は、破断伸びが少なくとも200%以上であることが好ましい。破断伸びが200%以上であれば、加硫成型時にシート状部材が金型の内表面の形状に良好に追従することができ、破れることがないからである。なお、本発明において、破断伸びは、JIS K6251に準拠し、イントロン引張り試験機(イントロン社製)を使用し、引張り速度、20±2mm/min、室温24±2℃の条件で測定することができる。   In the tread forming method according to the present invention, the sheet-like member is preferably made of a thermoplastic resin. This is because the thermoplastic resin can flexibly change its form during vulcanization molding, and unlike the thermosetting resin, the molecular structure does not change significantly during vulcanization molding. The sheet-like member preferably has an elongation at break of at least 200%. This is because when the elongation at break is 200% or more, the sheet-like member can follow the shape of the inner surface of the mold well at the time of vulcanization and is not torn. In the present invention, the elongation at break can be measured in accordance with JIS K6251 using an Intron tensile tester (manufactured by Intron) under the conditions of tensile speed, 20 ± 2 mm / min, and room temperature 24 ± 2 ° C. it can.

本発明に係るタイヤ用プレキュアトレッドは、上記形成方法のいずれかによって形成されることにより、ベアの発生を効果的かつ簡便に抑制することができる。   The tire precure tread according to the present invention is formed by any of the above forming methods, thereby effectively and easily suppressing the occurrence of bears.

本発明のトレッドの形成方法によれば、トレッドにベアが発生することを効果的かつ簡便に抑制することができる。   According to the tread forming method of the present invention, it is possible to effectively and simply suppress the occurrence of bears in the tread.

本発明に従うトレッドの形成方法の一例を示す、トレッド及び金型の幅方向の断面図である。It is sectional drawing of the width direction of a tread and a metal mold | die which shows an example of the formation method of the tread according to this invention. 本発明に従うトレッドの形成方法の一例を示す、トレッド及び金型の長手方向の断面図である。It is sectional drawing of the longitudinal direction of a tread and a metal mold | die which shows an example of the formation method of the tread according to this invention. 本発明に従うタイヤ用プレキュアトレッドの一例のトレッドの一部を示す平面図である。It is a top view which shows a part of tread of an example of the precure tread for tires according to this invention. 図3に示すトレッドのIV−IV線でのタイヤ幅方向断面図である。FIG. 4 is a tire width direction cross-sectional view of the tread shown in FIG. 3 taken along line IV-IV. 図3に示すトレッドのV−V線でのタイヤ周方向断面図である。FIG. 5 is a cross-sectional view in the tire circumferential direction along the line VV of the tread shown in FIG. 3.

以下、図面を参照しながら本発明のトレッドの形成方法及び該形成方法により形成されたトレッドについて詳細に説明する。ここで、本発明の形成方法を用いて形成するトレッドは、新品タイヤのトレッドであってもよいし、タイヤ用プレキュアトレッドのトレッドであってもよい。以下では、一例としてタイヤ用プレキュアトレッドのトレッドを形成する場合について説明する。   Hereinafter, a tread formation method and a tread formed by the formation method of the present invention will be described in detail with reference to the drawings. Here, the tread formed using the forming method of the present invention may be a tread of a new tire or a tread of a tire pre-cured tread. Below, the case where the tread of the precure tread for tires is formed as an example is demonstrated.

図1(a)〜(c)に、本発明に従うトレッドの形成方法の一例を用いてタイヤ用プレキュアトレッドのトレッドを形成する際の様子を、タイヤ用プレキュアトレッド及び金型の幅方向に沿う断面で示す。ここで、図1(a)に示すように、この一例の形成方法は、帯状の未加硫ゴムR’を金型M内で加硫成型してトレッド10を形成するトレッド成形工程を含んでいる。   FIGS. 1A to 1C show a state when forming a tread of a tire precure tread using an example of a tread formation method according to the present invention in the width direction of the tire precure tread and the mold. Shown in cross section. Here, as shown in FIG. 1A, this example of the forming method includes a tread forming step of forming a tread 10 by vulcanizing and molding a band-shaped unvulcanized rubber R ′ in a mold M. Yes.

トレッド成形工程では、図1(a)〜(c)に示すように、未加硫ゴムR’のうちトレッドが形成される部分(トレッド被形成部T’)と、金型Mの内表面MIのうちトレッド被形成部T’に当接するトレッド形成部MTとを当接させて加硫成型を行い、タイヤ用プレキュアトレッド10を形成する。そして、このトレッド成形工程では、未加硫ゴムR’のトレッド被形成部T’と、金型Mの内表面MIのトレッド形成部MTとの間に、所定のシート状部材6’を設置した状態で未加硫ゴムR’の加硫成型を行う。具体的には、未加硫ゴムR’の加硫成型は、トレッド被形成部T’とトレッド形成部MTとの間にシート状部材6’を設置した状態で、未加硫ゴムR’に圧力を負荷し、シート状部材6’を介してトレッド被形成部T’をトレッド形成部MTに押し付けると共に金型M内で未加硫ゴムR’を加熱することにより行う。なお、シート状部材6’をトレッド被形成部T’とトレッド形成部MTとの間に設置するとは、図1(a)に示したように、未加硫ゴムR’のトレッド被形成部T’にシート状部材6’を貼り付けることに加え、金型Mのトレッド形成部MTに、又は、トレッド形成部MTと未加硫ゴムR’のトレッド被形成部T’との双方にシート状部材6’を貼り付けることも含むものとする。   In the tread molding step, as shown in FIGS. 1A to 1C, a portion of the unvulcanized rubber R ′ where the tread is formed (tread formed portion T ′) and the inner surface MI of the mold M are formed. Of these, the tread forming portion MT that is in contact with the tread forming portion T ′ is brought into contact with each other to perform vulcanization molding, thereby forming the tire precure tread 10. In this tread molding step, a predetermined sheet-like member 6 ′ is installed between the tread formation portion T ′ of the unvulcanized rubber R ′ and the tread formation portion MT of the inner surface MI of the mold M. In this state, vulcanization molding of unvulcanized rubber R ′ is performed. Specifically, the vulcanization molding of the unvulcanized rubber R ′ is performed on the unvulcanized rubber R ′ with the sheet-like member 6 ′ installed between the tread formed portion T ′ and the tread formed portion MT. This is performed by applying pressure, pressing the tread formed portion T ′ against the tread forming portion MT through the sheet-like member 6 ′, and heating the unvulcanized rubber R ′ in the mold M. Note that the installation of the sheet-like member 6 ′ between the tread formation portion T ′ and the tread formation portion MT means that the tread formation portion T of the unvulcanized rubber R ′ as shown in FIG. In addition to affixing the sheet-like member 6 to the sheet, the sheet M is formed on the tread forming portion MT of the mold M or on both the tread forming portion MT and the tread formed portion T ′ of the unvulcanized rubber R ′. It also includes pasting the member 6 '.

ここで、トレッド成形工程で使用する金型Mのトレッド形成部MTは、形成されるタイヤ用プレキュアトレッド10のトレッドTの形状に対応した形状を有している。そして、トレッド形成部MTを用いて形成されたタイヤ用プレキュアトレッド10のトレッドTには、図3に示すように、周方向溝3及び幅方向溝4と、溝3,4によって区画形成されたブロック陸部5とが形成される。ここで、「周方向」及び「幅方向」とは、それぞれ、トレッドをタイヤに取り付けた場合を想定した、タイヤ周方向及びタイヤ幅方向に対応する方向をいうものとし、タイヤ周方向及びタイヤ幅方向は、それぞれ、プレキュアトレッド10の長手方向及び幅方向に相当する。   Here, the tread forming portion MT of the mold M used in the tread molding step has a shape corresponding to the shape of the tread T of the tire precure tread 10 to be formed. As shown in FIG. 3, the tread T of the tire precure tread 10 formed using the tread forming portion MT is partitioned and formed by a circumferential groove 3, a width direction groove 4, and grooves 3, 4. A block land portion 5 is formed. Here, “circumferential direction” and “width direction” mean directions corresponding to the tire circumferential direction and the tire width direction, respectively, assuming that the tread is attached to the tire, and the tire circumferential direction and the tire width. The directions correspond to the longitudinal direction and the width direction of the precure tread 10, respectively.

トレッド成形工程で使用する未加硫ゴムR’は、タイヤ及びプレキュアトレッドの製造において当該分野で一般的に使用されるゴム材料からなる帯状部材である。なお、「未加硫ゴム」には、部分的に加硫した半加硫ゴムも含まれるものとする。そして、未加硫ゴムR’のトレッド被形成部T’は、図1(a)〜(c)及び図2に示すように、ブロック陸部5の踏面50aが形成される踏面被形成部T1と、ブロック陸部5の側壁面50b,50d,50c,50eが形成される側壁面被形成部T2と、周方向溝3の溝底3Bが形成される溝底被形成部T3と、幅方向溝4の溝底4Bが形成される溝底被形成部T4とからなる。   The unvulcanized rubber R ′ used in the tread molding process is a belt-shaped member made of a rubber material generally used in the field in the manufacture of tires and precure treads. “Unvulcanized rubber” includes partially vulcanized semi-vulcanized rubber. The tread formed portion T ′ of the unvulcanized rubber R ′ is a tread formed portion T1 in which the tread surface 50a of the block land portion 5 is formed, as shown in FIGS. 1 (a) to 1 (c) and FIG. The side wall surface formed portion T2 where the side wall surfaces 50b, 50d, 50c, 50e of the block land portion 5 are formed, the groove bottom formed portion T3 where the groove bottom 3B of the circumferential groove 3 is formed, and the width direction It consists of a groove bottom formation portion T4 in which the groove bottom 4B of the groove 4 is formed.

ここで、このトレッド成形工程では、厚さ方向に連通した孔(以下、「厚さ方向の連通孔」という)と、該厚さ方向の連通孔と交差して延びる延在方向に連通した孔(以下、「延在方向の連通孔」という)とを有するシート状部材6’をトレッド被形成部T’とトレッド形成部MTとの間に配置した状態で未加硫ゴムR’を加硫成型する。従って、未加硫ゴムR’がシート状部材6’を介して加硫金型Mへ押し付けられる際に、トレッド被形成部T’とシート状部材6’との間に位置する空気や、未加硫ゴムR’内に含まれていた気体などが、まず厚さ方向の連通孔を介してトレッド形成部MT側に流れ、次いで、厚さ方向の連通孔と交差して延びる延在方向の連通孔を介してシート状部材6’の延在方向に流れることにより、金型M内から良好に排出される。よって、ベアの発生を効果的かつ簡便に抑制することができる。なお、ここで「延在方向」とは、シート状部材6’の厚さ方向に直交する方向をいう。また、シート状部材6’の厚さ方向の連通孔及び延在方向の連通孔は、例えば、複数の微小孔がシート状部材の厚さ方向及び/又は延在方向に連なって構成されたもの(即ち、連続気泡よりなる孔)である。これらの孔は直線状に延在するものであってもよく、蛇行していてもよい。また、シート状部材6’は、独立気泡を更に含んでいてもよい。   Here, in this tread forming step, a hole communicating in the thickness direction (hereinafter referred to as “a communication hole in the thickness direction”) and a hole communicating in the extending direction extending across the communication hole in the thickness direction. The unvulcanized rubber R ′ is vulcanized in a state in which the sheet-like member 6 ′ having “the communication hole in the extending direction” is disposed between the tread formation portion T ′ and the tread formation portion MT. Mold. Accordingly, when the unvulcanized rubber R ′ is pressed against the vulcanizing mold M through the sheet-like member 6 ′, air positioned between the tread forming portion T ′ and the sheet-like member 6 ′, The gas or the like contained in the vulcanized rubber R ′ first flows to the tread forming portion MT side through the communication hole in the thickness direction, and then extends in the extending direction extending across the communication hole in the thickness direction. By flowing in the extending direction of the sheet-like member 6 ′ through the communication hole, the sheet M is discharged well from the inside of the mold M. Therefore, it is possible to effectively and easily suppress the generation of bears. Here, the “extending direction” refers to a direction orthogonal to the thickness direction of the sheet-like member 6 ′. Further, the communication hole in the thickness direction and the communication hole in the extending direction of the sheet-like member 6 ′ are, for example, configured such that a plurality of minute holes are continuous in the thickness direction and / or the extending direction of the sheet-like member. (That is, holes made of open cells). These holes may extend linearly or may meander. Further, the sheet-like member 6 ′ may further include closed cells.

そして、金型Mと未加硫ゴムR’との間に設置したシート状部材6’を介して金型Mから空気が良好に排出されるため、複数段の加硫金型を具えた加硫装置を用いて複数種のタイヤ用プレキュアトレッドを同時に製造する場合であっても、ベアの発生を抑制したプレキュアトレッドを容易に製造することができる。更に、上記形成方法によれば、長手方向のピッチが比較的大きなプレキュアトレッドを製造することができる。   And since air is discharged | emitted favorably from the metal mold | die M through the sheet-like member 6 'installed between the metal mold | die M and the unvulcanized rubber R', the process which provided the multistage vulcanization metal mold | die Even in the case where a plurality of types of tire precure treads are produced at the same time using a sulfur apparatus, a precure tread with suppressed generation of bears can be easily produced. Furthermore, according to the above forming method, a precure tread having a relatively large longitudinal pitch can be produced.

ここで、上述した通り、シート状部材6’の厚さ方向の連通孔及び延在方向の連通孔を介して、金型M内から気体が良好に排出される。そのため、本発明の形成方法では、気体を効率的に排出する観点からは、シート状部材6’を、トレッド被形成部T’全体に設けることが望ましい。しかしながら、本願発明者らの鋭意研究の結果、トレッド被形成部T’のうちの溝底被形成部T3,T4にシート状部材6’を設置して加硫成型したトレッドを有するタイヤは、タイヤの走行時に溝底に亀裂が発生しやすいことが明らかとなった。一方で、溝底被形成部T3,T4にシート状部材6’を設置しない場合であっても、トレッド部、特にエッジ部におけるベアの発生を十分に抑制できることも明らかとなった。
そこで、上記成形工程では、溝底の亀裂の発生を低減するため、図1(b)に示すように、トレッド被形成部T’のうち、溝底被形成部(T3及びT4)の少なくとも一部(この例においては、周方向溝底被形成部T3)を覆わないようにシート状部材6’を設置することが好ましい。言い換えれば、シート状部材6’は、溝底の亀裂の発生を抑制する観点からは、踏面被形成部T1及び側壁面被形成部T2のみを覆う位置に設置することが好ましく、溝底の亀裂の発生を抑制しつつシート状部材6’の設置を容易にする観点からは、トレッド被形成部T’のうち、溝底被形成部の少なくとも一部を覆わないように設置することが好ましい。
Here, as described above, the gas is satisfactorily discharged from the mold M through the communication hole in the thickness direction and the communication hole in the extending direction of the sheet-like member 6 ′. Therefore, in the forming method of the present invention, it is desirable to provide the sheet-like member 6 ′ over the entire tread formation portion T ′ from the viewpoint of efficiently discharging the gas. However, as a result of diligent research by the inventors of the present application, a tire having a tread formed by vulcanizing and molding a sheet-like member 6 ′ in the groove bottom formed portions T3, T4 of the tread formed portion T ′ is a tire. It was revealed that cracks are likely to occur at the bottom of the groove during running. On the other hand, even when the sheet-like member 6 ′ is not installed in the groove bottom covered portions T3 and T4, it has been clarified that generation of bears in the tread portion, particularly the edge portion, can be sufficiently suppressed.
Therefore, in the molding step, in order to reduce the occurrence of cracks in the groove bottom, as shown in FIG. 1B, at least one of the groove bottom formed portions (T3 and T4) in the tread formed portion T ′. It is preferable to install the sheet-like member 6 ′ so as not to cover the portion (in this example, the circumferential groove bottom covering portion T3). In other words, from the viewpoint of suppressing the occurrence of cracks in the groove bottom, the sheet-like member 6 ′ is preferably installed at a position that covers only the tread surface formed portion T1 and the side wall surface formed portion T2. From the viewpoint of facilitating the installation of the sheet-like member 6 ′ while suppressing the occurrence of the occurrence, it is preferable that the tread formation portion T ′ is installed so as not to cover at least a part of the groove bottom formation portion.

このように、シート状部材6’を、溝底被形成部の少なくとも一部(この例においては、周方向溝底被形成部T3)には設置せず、側壁面被形成部T2及び踏面被形成部T1の範囲内であって、少なくとも側壁面被形成部T1と踏面被形成部T2との境界線(図示せず)上を覆う位置、並びに、幅方向溝底被形成部T4を覆う位置に設置し、加硫成型を行うことによって、シート状部材6’を溝底被形成部の全て(T3,T4)に設置した場合と比較して、タイヤ走行時に溝底3Bに亀裂が生じることを抑制することができる。
そして、この場合、側壁面被形成部T2及び踏面被形成部T1の範囲内であって、少なくとも側壁面被形成部T2と踏面被形成部T1との境界線上を覆う位置にシート状部材6’を設置した状態で加硫成型が行われるので、陸部5(サイプSが配設されているものを含む)のエッジ部分におけるベアの発生を効果的に抑制することができる。
従って、上記位置にシート状部材6’を設置して加硫成型することによって、トレッドにベアが発生することを効果的に抑制することができると共に、溝底における亀裂の発生を低減することができる。
In this way, the sheet-like member 6 ′ is not installed on at least a part of the groove bottom covering portion (in this example, the circumferential groove bottom covering portion T3), and the side wall surface forming portion T2 and the tread surface covering are not provided. A position within the range of the forming portion T1 and covering at least a boundary line (not shown) between the side wall surface formed portion T1 and the tread surface formed portion T2 and a position covering the width direction groove bottom formed portion T4 And the vulcanization molding causes cracks in the groove bottom 3B during running of the tire as compared to the case where the sheet-like member 6 ′ is installed in all of the groove bottom covered portions (T3, T4). Can be suppressed.
In this case, the sheet-like member 6 ′ is located within the range of the side wall surface formed portion T2 and the tread surface formed portion T1, and at least covers the boundary line between the side wall surface formed portion T2 and the tread surface formed portion T1. Since the vulcanization molding is performed in a state where the slab is installed, it is possible to effectively suppress the occurrence of bears at the edge portion of the land portion 5 (including the sipe S).
Therefore, by installing the sheet-like member 6 ′ at the above position and performing vulcanization molding, it is possible to effectively suppress the occurrence of bears in the tread and reduce the occurrence of cracks at the groove bottom. it can.

また、本発明の形成方法では、シート状部材6’が有する厚さ方向の連通孔及び延在方向の連通孔の数は、それぞれ1つ以上であれば任意の数とすることができる。具体的には、シート状部材6’は、厚さ方向の連通孔及び延在方向の連通孔を多数有する多孔質部材であってもよい。また、厚さ方向の連通孔及び延在方向の連通孔は、シート状部材6’の一部に設けられていてもよいし、シート状部材6’の全体に亘って設けられていてもよい。   In the forming method of the present invention, the number of the communication holes in the thickness direction and the communication holes in the extending direction of the sheet-like member 6 ′ can be any number as long as it is one or more. Specifically, the sheet-like member 6 ′ may be a porous member having a large number of communicating holes in the thickness direction and communicating holes in the extending direction. Further, the communication hole in the thickness direction and the communication hole in the extending direction may be provided in a part of the sheet-like member 6 ′, or may be provided over the entire sheet-like member 6 ′. .

上記成形工程で使用するシート状部材6’の枚数は、特に限定されず、上述の設置範囲を覆うことができれば、任意の枚数であってよい。
例えば、長尺のシート状部材6’を3枚使用し、このシート状部材6’を帯状の未加硫ゴムR’のトレッド被形成部T’の長手方向に沿って、周方向溝被形成部T3を覆わないように設置する。この場合、3枚のシート状部材6’の幅方向の寸法は、そのシート状部材が貼り付けられるブロック陸部5の踏面の幅方向の寸法と、側壁面の寸法(踏面と側壁面との境界線から溝底までの最短距離)との合計未満であってよい。
The number of sheet-like members 6 ′ used in the molding step is not particularly limited, and may be any number as long as the above installation range can be covered.
For example, three long sheet-like members 6 ′ are used, and this sheet-like member 6 ′ is formed along the longitudinal direction of the tread formation portion T ′ of the belt-like unvulcanized rubber R ′. Install so as not to cover part T3. In this case, the widthwise dimensions of the three sheet-like members 6 ′ are the widthwise dimension of the tread surface of the block land portion 5 to which the sheet-like member is attached and the dimension of the side wall surface (the tread surface and the side wall surface The shortest distance from the boundary line to the groove bottom) may be less than the sum.

そして、シート状部材6’は、トレッド成形工程における、加熱温度及び加圧圧力で溶解しない又は孔を塞ぐことがないものであり、且つ、加熱及び加圧によって未加硫ゴムR’と反応しないものからなることが好ましい。   And sheet-like member 6 'is a thing which is not melt | dissolved by heating temperature and pressurization pressure in a tread shaping | molding process, or does not block | close a hole, and does not react with unvulcanized rubber R' by heating and pressurization. It is preferable to consist of things.

具体的には、シート状部材6’は、例えば、樹脂系材料からなる。樹脂系材料としては、例えば、ウレタン、ナイロン、ゴム等の熱可塑性樹脂、並びに、ガラス繊維、プラスチック等の熱硬化性樹脂が挙げられる。シート状部材6’は、例えば、先述の材料を発泡させてなるものであっても、先述の材料の繊維を編んで形成したものであってもよい。   Specifically, the sheet-like member 6 'is made of, for example, a resin material. Examples of the resin material include thermoplastic resins such as urethane, nylon, and rubber, and thermosetting resins such as glass fiber and plastic. For example, the sheet-like member 6 ′ may be formed by foaming the above-described material, or may be formed by knitting fibers of the above-described material.

これらの中でも、シート状部材6’としては、好ましくは、熱可塑性樹脂からなるものが使用される。シート状部材6’が熱可塑性樹脂からなる場合、加硫成型時に形態を柔軟に変化させることができ、また、熱硬化性樹脂とは異なり、加硫成型時に分子構造が大幅に変化することがない。また、熱可塑性樹脂からなるシート状部材6’は、初期走行によって形成後のトレッドから容易に除去することができるため、走行時の性能にはほとんど悪影響を及ぼさず、製造過程においてシート状部材6’を除去するための更なる工程を設ける必要がない。   Among these, the sheet-like member 6 ′ is preferably made of a thermoplastic resin. When the sheet-like member 6 ′ is made of a thermoplastic resin, the form can be changed flexibly during vulcanization molding, and unlike the thermosetting resin, the molecular structure can change significantly during vulcanization molding. Absent. Further, since the sheet-like member 6 ′ made of a thermoplastic resin can be easily removed from the tread after the formation by the initial running, the performance during running is hardly adversely affected, and the sheet-like member 6 ′ is produced in the manufacturing process. There is no need to provide an additional step for removing '.

特に好ましくは、シート状部材6’としては、ウレタンからなるものが使用される。樹脂系材料としてウレタンを使用する場合には、加硫成型時に、未加硫ゴムR’が加硫金型Mの凹面にスムーズに流れ込むことができる。更に、ウレタンからなるシート状部材6’を使用すると、金型Mからのプレキュアトレッド10の離型性が向上する。そのため、ウレタン製のシート状部材6’を使用した場合には、従来、金型に塗布していた離型剤を使用する必要がない。例えば、発泡ポリウレタンのブロック状の塊を0.1〜3mmの厚さにピーリングして得た部材を、シート状部材6’として使用することができる。   Particularly preferably, the sheet-like member 6 'is made of urethane. When urethane is used as the resin-based material, the unvulcanized rubber R ′ can smoothly flow into the concave surface of the vulcanization mold M during vulcanization molding. Furthermore, when the sheet-like member 6 ′ made of urethane is used, the releasability of the precure tread 10 from the mold M is improved. Therefore, when the urethane sheet-like member 6 'is used, it is not necessary to use a release agent that has been applied to the mold. For example, a member obtained by peeling a block-like lump of polyurethane foam to a thickness of 0.1 to 3 mm can be used as the sheet-like member 6 '.

シート状部材6’の厚さは、上述した通り、例えば0.1〜3mmである。シート状部材6’の厚さが3mmを超えるとシート状部材6’内に一部空気がトラップされ易くなるため、3mm以下の厚さのものを使用することでより効果的にベアの発生を抑制することができる。シート状部材6’の厚さは、更に好ましくは、0.1〜0.8mmである。シート状部材6’の厚さが厚いほど、シート状部材6’が摩耗してなくなるまでの間のタイヤ性能、即ち走行初期のタイヤ性能に悪影響を及ぼす可能性が高く、特にゴムのグリップ力が必要となる制動性能が低下する懸念がある。シート状部材6’の厚さを0.8mm以下とすると、タイヤ性能に殆ど影響を及ぼさないことがわかっている。更に、シート状部材6’の厚さが0.8mm以下の場合には、溝底にシート状部材6’を配置した場合でも、溝底に亀裂が生じないこともわかった。即ち、溝底の亀裂の発生は、先に述べたように溝底にシート状部材6’を設置しないことにより、及び/又は、シート状部材6’の厚さを0.8mm以下とすることによって防ぐことができる。また、シート状部材6’の厚さが0.1mm未満の場合、貼付け精度や生産性が低下する。即ち、シート状部材6’の厚さを0.1〜0.8mmの範囲とすることで、生産性、タイヤ性能及びタイヤの外観を損なうことなく、ベアの発生を抑制することができる。   As described above, the thickness of the sheet-like member 6 ′ is, for example, 0.1 to 3 mm. If the thickness of the sheet-like member 6 ′ exceeds 3 mm, air is easily trapped in the sheet-like member 6 ′. Can be suppressed. The thickness of the sheet-like member 6 ′ is more preferably 0.1 to 0.8 mm. The thicker the sheet-like member 6 ′, the higher the possibility that it will adversely affect the tire performance until the sheet-like member 6 ′ is no longer worn, that is, the tire performance at the beginning of running. There is a concern that the required braking performance will decrease. It has been found that when the thickness of the sheet-like member 6 'is 0.8 mm or less, the tire performance is hardly affected. Furthermore, it was also found that when the thickness of the sheet-like member 6 'is 0.8 mm or less, no crack is generated at the groove bottom even when the sheet-like member 6' is disposed at the groove bottom. That is, the occurrence of cracks in the groove bottom is caused by not installing the sheet-like member 6 ′ on the groove bottom as described above and / or making the thickness of the sheet-like member 6 ′ 0.8 mm or less. Can be prevented by. On the other hand, when the thickness of the sheet-like member 6 ′ is less than 0.1 mm, the pasting accuracy and productivity are lowered. That is, by setting the thickness of the sheet-like member 6 ′ within the range of 0.1 to 0.8 mm, it is possible to suppress the occurrence of bears without impairing productivity, tire performance, and tire appearance.

そして、シート状部材6’は、破断伸びが200%以上、好ましくは350%以上であることが好ましい。破断伸びが前記範囲にあるシート状部材6’を使用することによって、加硫成型時にシート状部材6’が金型の内表面MIの形状に追従することができ、シート状部材6’が破れることがない。従って、シート状部材6’を配置した部分において空気を金型からより効率的に排出させて、より効果的にベアを抑制した所望の形状を有するトレッドを形成することができる。   The sheet-like member 6 'has a breaking elongation of 200% or more, preferably 350% or more. By using the sheet-like member 6 ′ whose break elongation is in the above range, the sheet-like member 6 ′ can follow the shape of the inner surface MI of the mold during vulcanization molding, and the sheet-like member 6 ′ is torn. There is nothing. Therefore, air can be more efficiently discharged from the mold at the portion where the sheet-like member 6 ′ is disposed, and a tread having a desired shape in which bears are more effectively suppressed can be formed.

シート状部材6’が含む厚さ方向の連通孔のうち、トレッド被形成部T’の表面において最大の開口面積を有する孔は、ブロック陸部のうち、最小の踏面面積を有するブロック陸部の踏面の面積よりも小さいことが好ましい。孔の面積がブロック陸部の最小の踏面面積よりも大きいと、トレッド被形成部T’とシート状部材6’との間に位置する空気や、未加硫ゴムR’内に含まれていた気体を効果的に排出することができず、ベアの発生を抑制できない可能性がある。例えば、孔のサイズは、10μm〜10mmである。   Of the communication holes in the thickness direction included in the sheet-like member 6 ′, the hole having the maximum opening area on the surface of the tread formation portion T ′ is the block land portion having the minimum tread surface area among the block land portions. It is preferably smaller than the area of the tread. When the area of the hole is larger than the minimum tread surface area of the block land portion, it was included in the air positioned between the tread formed portion T ′ and the sheet-like member 6 ′ or in the unvulcanized rubber R ′. There is a possibility that the gas cannot be effectively discharged and the generation of bears cannot be suppressed. For example, the size of the hole is 10 μm to 10 mm.

そして、シート状部材6’の厚さ方向の連通孔の総開口面積は、厚さ方向の連通孔の開口が存在していないと仮定したシート状部材6’の表面の面積の30%を超えることが好ましい。ここで、シート状部材6’の厚さ方向の連通孔の総開口面積の割合は、発泡材の発泡率に相当する。この割合が低すぎると、トレッド被形成部T’と金型Mのトレッド形成部MTとの間から空気を排出する効果が十分に得られず、ベアの発生を抑制できない可能性がある。   The total opening area of the communication holes in the thickness direction of the sheet-like member 6 ′ exceeds 30% of the area of the surface of the sheet-like member 6 ′, assuming that there is no opening of the communication holes in the thickness direction. It is preferable. Here, the ratio of the total opening area of the communication holes in the thickness direction of the sheet-like member 6 ′ corresponds to the foaming rate of the foamed material. If this ratio is too low, the effect of exhausting air from between the tread formation portion T ′ and the tread formation portion MT of the mold M cannot be sufficiently obtained, and the generation of bears may not be suppressed.

トレッド被形成部T’とトレッド形成部MTとの間にシート状部材6’を設置した状態で未加硫ゴムR’を加硫成型した場合、図4及び図5に示す通り、プレキュアトレッド10のトレッドTの表層部には、シート状部材6’を含んだ表面層6が形成される。   When the unvulcanized rubber R ′ is vulcanized and molded with the sheet-like member 6 ′ installed between the tread forming portion T ′ and the tread forming portion MT, as shown in FIG. 4 and FIG. A surface layer 6 including a sheet-like member 6 ′ is formed on the surface layer portion of the tread T of 10.

ここで、トレッド成形工程では、圧力を負荷することによって、未加硫ゴムR’がシート状部材6’の連通孔に流入し、加熱して加硫を行うことで、連通孔に流入した未加硫ゴムR’が加硫されて加硫ゴムRとなる。従って、形成された表面層6は、シート状部材6’と、シート状部材6’の少なくとも一部の連通孔の内部に存在する加硫ゴムRとを含んでいる。   Here, in the tread molding process, unvulcanized rubber R ′ flows into the communication hole of the sheet-like member 6 ′ by applying a pressure, and is heated and vulcanized so that the unvulcanized rubber R ′ flows into the communication hole. Vulcanized rubber R ′ is vulcanized to form vulcanized rubber R. Therefore, the formed surface layer 6 includes a sheet-like member 6 ′ and a vulcanized rubber R existing inside at least a part of the communication holes of the sheet-like member 6 ′.

トレッド成形工程において、シート状部材6’を、踏面被形成部T1及び側壁面被形成部T2、並びに、幅方向溝底被形成部T4を覆う位置に設置したことにより、図4及び5に示すように、側壁面50b,50d及び踏面50aの範囲内であって、側壁面50b,50dと踏面50aとの境界線L2の上を覆う位置、並びに、側壁面50c,50e及び幅方向溝底4を覆う位置に、表面層6が形成される。即ち、表面層6は、加硫後のトレッド10の表面のうちの、周方向溝底3B以外の部分を覆う位置に形成されている。ここで、「トレッドの表面」又は「トレッド表面」は、トレッドのブロック陸部の側壁面50b,50c,50d,50e、踏面50a、並びに、周方向及び幅方向溝底3B,4Bかならなるものとする。   In the tread forming step, the sheet-like member 6 ′ is installed at a position that covers the tread surface formed portion T1, the side wall surface formed portion T2, and the width direction groove bottom formed portion T4, as shown in FIGS. Thus, within the range of the side wall surfaces 50b and 50d and the tread surface 50a, the position covering the boundary line L2 between the side wall surfaces 50b and 50d and the tread surface 50a, and the side wall surfaces 50c and 50e and the width direction groove bottom 4 A surface layer 6 is formed at a position covering the surface. That is, the surface layer 6 is formed at a position covering the portion of the surface of the tread 10 after vulcanization other than the circumferential groove bottom 3B. Here, the “tread surface” or “tread surface” is composed of the side wall surfaces 50b, 50c, 50d, 50e, the tread surface 50a of the tread block land portion, and the circumferential and width direction groove bottoms 3B, 4B. And

表面層6を上記範囲に形成することによって、表面層6をトレッドTの表層部の全範囲に形成する場合と比較して、タイヤ走行時に溝底3Bに亀裂が生じることを抑制することができる。即ち、トレッドにベアが発生することを効果的に抑制することができると共に、タイヤ走行時の溝底における亀裂の発生を低減することができる。   By forming the surface layer 6 in the above range, it is possible to suppress the occurrence of cracks in the groove bottom 3B when the tire is running, as compared with the case where the surface layer 6 is formed in the entire range of the surface layer portion of the tread T. . That is, it is possible to effectively suppress the occurrence of bears in the tread, and to reduce the occurrence of cracks at the groove bottom when the tire is running.

そして、表面層6は、タイヤ側壁面50b,50c,50d,50eのそれぞれにおいて、ブロック陸部5のタイヤ径方向外側端からタイヤ径方向内側に向かって前記ブロック陸部5の高さの好ましくは30%の範囲までを覆う位置に位置する。このような範囲に表面層6が形成されることによって、走行末期に溝底に表面層6が残ることがないため、溝底で亀裂が発生するのを抑制することができる。ここで、「ブロック陸部の高さ」とは、図4及び5に示す通り、溝底3B(又は4B)の最も深い位置から、ブロック陸部踏面50aまでのタイヤ径方向に沿う距離H1(又はH2)をいう。   The surface layer 6 preferably has a height of the block land portion 5 from the outer end in the tire radial direction of the block land portion 5 toward the inner side in the tire radial direction on each of the tire side wall surfaces 50b, 50c, 50d, and 50e. It is located at a position covering up to 30% of the range. By forming the surface layer 6 in such a range, the surface layer 6 does not remain at the bottom of the groove at the end of traveling, so that the generation of cracks at the bottom of the groove can be suppressed. Here, as shown in FIGS. 4 and 5, the “height of the block land portion” is a distance H1 (in the tire radial direction from the deepest position of the groove bottom 3B (or 4B) to the block land portion tread 50a ( Or H2).

そして、表面層6の厚さは、トレッドの厚さの2分の1未満であることが好ましい。表面層6の厚さが厚すぎると、連通孔の存在によって走行時の性能に悪影響を及ぼすことがあるためである。   And it is preferable that the thickness of the surface layer 6 is less than half of the thickness of a tread. This is because if the surface layer 6 is too thick, the presence of the communication hole may adversely affect the running performance.

先に説明した本発明の一例では、トレッド成形工程において、シート状部材6’を、側壁面被形成部T2及び踏面被形成部T1の範囲内、並びに、幅方向溝底被形成部4Bに設置することにより、表面層6を、側壁面50b,50d及び踏面50aの範囲内、並びに、側壁面50c,50e及び幅方向溝底4Bに形成した。しかしながら、シート状部材6’を、幅方向溝底被形成部4Bの代わりに周方向溝底被形成部3Bに設置し、表面層6を、幅方向溝底4Bでなく、周方向溝底3Bに形成してもよい。なお、タイヤ走行時の溝底の亀裂の発生を低減するためには、表面層6は、側壁面50b,50c,50c,50d及び踏面50aの範囲内であって、少なくとも前記側壁面と前記踏面との境界線上を覆う位置にのみ設置し(周方向溝底被形成部3B及び幅方向溝底被形成部4Bに設置せず)、表面層6を、側壁面50b,50c,50c,50d及び踏面50aの範囲内のみに形成することが好ましい。   In the example of the present invention described above, in the tread forming step, the sheet-like member 6 ′ is installed in the range of the side wall surface forming portion T2 and the tread surface forming portion T1 and in the width direction groove bottom forming portion 4B. By doing so, the surface layer 6 was formed in the range of the side wall surfaces 50b and 50d and the tread surface 50a, and on the side wall surfaces 50c and 50e and the width direction groove bottom 4B. However, the sheet-like member 6 ′ is installed in the circumferential groove bottom covering portion 3B instead of the width direction groove bottom covering portion 4B, and the surface layer 6 is not the width direction groove bottom 4B but the circumferential groove bottom 3B. You may form in. In order to reduce the occurrence of cracks in the groove bottom during running of the tire, the surface layer 6 is within the range of the side wall surfaces 50b, 50c, 50c, 50d and the tread surface 50a, and at least the side wall surface and the tread surface. Is installed only at a position covering the boundary line (not installed in the circumferential groove bottom covered portion 3B and the width direction groove bottom covered portion 4B), and the surface layer 6 is placed on the side wall surfaces 50b, 50c, 50c, 50d and It is preferable to form only within the range of the tread surface 50a.

上記説明では、トレッド2は、更正タイヤをプレキュア方式で製造する場合に使用するプレキュアトレッドについて説明したが、上記形成方法は、更正タイヤのリモールド方式で製造する場合や新品タイヤを製造する場合にも適用することができる。   In the above description, the tread 2 has been described with respect to the precure tread that is used when the corrected tire is manufactured by the precure method. However, the above forming method is used when the rectified tire is manufactured by the remolding method or when a new tire is manufactured. Can also be applied.

また、上述したトレッドパターンは一例であり、本発明のトレッドの形成方法により形成されるトレッドパターンはこれに限られない。そして、形成するトレッドパターンに応じて、シート状部材6’の形状及び枚数は適宜変更されてよい。   Moreover, the tread pattern mentioned above is an example, and the tread pattern formed by the tread forming method of the present invention is not limited to this. And according to the tread pattern to form, the shape and number of sheet-like members 6 'may be changed as appropriate.

(実施例1)
Bandag社によって配合された未加硫ゴム(T534)のトレッド被形成部T’の全域に渡って、厚さ0.8mmの発泡ウレタンシートを設置し、3段のトレッド用加硫金型を備えたPCT(プレキュアトレッド)プレス機(Bandag社製)により加硫成型を行い、プレキュアトレッドを製造した。ここで、使用した発泡ウレタンシートは、厚さ方向の連通孔と、該厚さ方向の連通孔と交差して延びる延在方向の連通孔とを有し、破断伸びは350%、発泡率は50%であった。
Example 1
A foam urethane sheet with a thickness of 0.8 mm is installed over the entire tread formation part T ′ of unvulcanized rubber (T534) blended by Bandag, and a three-stage tread vulcanization mold is provided. Vulcanization molding was performed with a PCT (precure tread) press machine (manufactured by Bandag) to produce a precure tread. Here, the urethane foam sheet used has a communication hole in the thickness direction and a communication hole in the extending direction extending across the communication hole in the thickness direction, the elongation at break is 350%, and the foaming rate is 50%.

(実施例2)
発泡ウレタンシートを、踏面被形成部T1と、ブロック陸部5のタイヤ径方向外側端からタイヤ径方向内側に向かってブロック陸部5の高さの30%の範囲とに、踏面被形成部T1と側壁面被形成部T2との境界線上を覆うように設置し、それ以外の部分には設置しなかったこと以外は実施例1と同様にして、プレキュアトレッドを製造した。
(実施例3〜6)
実施例3〜6ではそれぞれ、厚さが、1.0mm、2.0mm、3.0mm及び4.0mmの発泡ポリウレタンシートを使用したこと以外は実施例1と同様にして、プレキュアトレッドを製造した。
(実施例7)
発泡率30%、厚さ0.8mmの発泡ポリウレタンシートを用いたこと以外は、実施例1と同様にしてプレキュアトレッドを製造した。
(Example 2)
The foamed urethane sheet is placed on the tread surface forming portion T1 and the tread surface forming portion T1 within a range of 30% of the height of the block land portion 5 from the tire radial direction outer side end of the block land portion 5 toward the tire radial direction inner side. A pre-cured tread was produced in the same manner as in Example 1 except that it was installed so as to cover the boundary line between the portion T2 and the side wall surface formed portion T2, and was not installed in other portions.
(Examples 3 to 6)
In Examples 3 to 6, precured treads were produced in the same manner as in Example 1 except that foamed polyurethane sheets having thicknesses of 1.0 mm, 2.0 mm, 3.0 mm, and 4.0 mm were used. did.
(Example 7)
A precure tread was produced in the same manner as in Example 1 except that a foamed polyurethane sheet having a foaming rate of 30% and a thickness of 0.8 mm was used.

(比較例1)
発泡ポリウレタンシートを設置しなかったこと以外は、実施例1と同様にしてプレキュアトレッドを製造した。
(比較例2)
実施例1で使用した発泡ポリウレタンシートの代わりに、独立気泡型発泡ゴムシートを使用したこと以外は実施例1と同様にしてプレキュアトレッドを製造した。使用した独立気泡型発泡ゴムシートの厚さ及び発泡率はそれぞれ、実施例1で用いた発泡ウレタンシートと同じ0.8mm及び50%であった。
(Comparative Example 1)
A precure tread was produced in the same manner as in Example 1 except that the polyurethane foam sheet was not installed.
(Comparative Example 2)
A precure tread was produced in the same manner as in Example 1 except that a closed cell foam rubber sheet was used instead of the foamed polyurethane sheet used in Example 1. The thickness and foaming rate of the used closed cell foamed rubber sheet were 0.8 mm and 50%, respectively, which were the same as the foamed urethane sheet used in Example 1.

<1.ベア発生有無の評価>
実施例及び比較例で製造したプレキュアトレッドのベアの発生を目視で評価した。結果を下記表1に示す。表1中、ベアの発生は、比較例1のベアの発生個数を100として、相対的な数値で表す。
評価の結果、実施例で形成したプレキュアトレッドにはベアが全く発生せず、比較例で形成したプレキュアトレッドには、全てのブロック角でベアが発生していた。
<1. Evaluation of bear occurrence>
Generation | occurrence | production of the bear of the precure tread manufactured by the Example and the comparative example was evaluated visually. The results are shown in Table 1 below. In Table 1, the occurrence of bears is expressed as a relative numerical value, where the number of bears generated in Comparative Example 1 is 100.
As a result of the evaluation, no bear was generated at all in the precure tread formed in the example, and bear was generated at all block angles in the precure tread formed in the comparative example.

次いで、実施例及び比較例で形成したプレキュアトレッドを使用して供試タイヤ(タイヤサイズ245/70R19.5)を製造し、該タイヤを以下の評価及び試験に供した。   Next, test tires (tire size 245 / 70R19.5) were manufactured using the precure treads formed in Examples and Comparative Examples, and the tires were subjected to the following evaluations and tests.

<2.溝底亀裂発生有無の評価>
製造した各供試タイヤを、ドラム試験機に取り付け、正規内圧で、80km/hの速度に相当する回転ドラム上に最大負荷荷重を負荷し30,000km走行させた。走行後のタイヤの溝底を目視観察して、亀裂発生の有無を評価した。なお、ここで、正規内圧及び最大負荷荷重は、使用される地域に有効な産業規格であって、日本ではJATMA(日本自動車タイヤ協会) YEAR BOOK、欧州ではETRTO(European Tyre and Rim Technical Organisation)STANDARD MANUAL、米国ではTRA(THE TIRE and RIM ASSOCIATION INC.)YEAR BOOK等の規定に従うものである。
<3.制動性能の評価>
各供試タイヤを、JATMA規格に定めるリム(6J×15)に組み付け、車両(2000ccの乗用車の4輪)に装着し、内圧200kPa、荷重(2.0t)の条件下、ドライバーがドライ路面のテストコースを時速30km/hで走行して車両のブレーキが掛けられてから0km/hとなるまでの停止距離を測定した。結果は、比較例タイヤ1の停止距離の逆数を100として指数表示した。なお、評価結果は、指数が大きいほど性能に優れていることを示し、指数80以上が、性能良好と判断されるものとする。
<2. Evaluation of presence or absence of groove bottom cracks>
Each of the manufactured test tires was attached to a drum testing machine, and was run at 30,000 km with a maximum load applied on a rotating drum corresponding to a speed of 80 km / h at normal internal pressure. The tire bottom after running was visually observed to evaluate the presence or absence of cracks. Here, the normal internal pressure and the maximum load load are industrial standards effective in the region where they are used. In Japan, JATMA (Japan Automobile Tire Association) YEAR BOOK, in Europe, ETRTO (European Tire and Rim Technical Organization) STANDARD. MANUAL, in the United States, conforms to TRA (THE TIRE and RIM ASSOCIATION INC.) YEAR BOOK etc.
<3. Evaluation of braking performance>
Each test tire is mounted on a rim (6J × 15) defined in JATMA standard and mounted on a vehicle (four wheels of a 2000cc passenger car). Traveling on the test course at a speed of 30 km / h, the stopping distance from when the vehicle was braked to 0 km / h was measured. The results are shown as an index with the reciprocal of the stopping distance of the comparative example tire 1 being 100. The evaluation result indicates that the larger the index is, the better the performance is, and an index of 80 or more is judged to be good.

Figure 2014213506
Figure 2014213506

3…周方向溝、4…幅方向溝、3B…周方向溝底、4B…幅方向溝底、5…ブロック陸部、6’…シート状部材、6…表面層、10…プレキュアトレッド、50a…踏面、50b、50d…周方向側壁面、50c,50e…幅方向側壁面、L1…側壁面と側壁面との境界線、L2…側壁面と踏面との境界線、M…加硫金型、MI…金型内表面、MT…トレッド形成部、T’…トレッド被形成部、T…トレッド、T1…踏面被形成部、T2…側壁面被形成部、T3…周方向溝底被形成部、T4…幅方向溝底被形成部、TE…トレッド端、R’…未加硫ゴム、R…加硫ゴム、S…サイプ DESCRIPTION OF SYMBOLS 3 ... Circumferential groove, 4 ... Width direction groove, 3B ... Circumferential groove bottom, 4B ... Width direction groove bottom, 5 ... Block land part, 6 '... Sheet-like member, 6 ... Surface layer, 10 ... Precure tread, 50a ... Tread surface, 50b, 50d ... Circumferential side wall surface, 50c, 50e ... Width side wall surface, L1 ... Boundary line between side wall surface and side wall surface, L2 ... Boundary line between side wall surface and tread surface, M ... Vulcanized gold Mold, MI ... inner surface of mold, MT ... tread forming part, T '... tread forming part, T ... tread, T1 ... tread surface forming part, T2 ... side wall surface forming part, T3 ... circumferential groove bottom covering formation Part, T4 ... width direction groove bottom covering part, TE ... tread end, R '... unvulcanized rubber, R ... vulcanized rubber, S ... sipe

Claims (8)

未加硫ゴムを金型内で加硫成型してトレッドを形成するトレッド成形工程を含み、
前記トレッド成形工程では、前記トレッドが形成される未加硫ゴムのトレッド被形成部と、前記金型の内表面のうち前記トレッド被形成部に当接するトレッド形成部との間に、厚さ方向の連通孔及び該厚さ方向の連通孔と交差して延びる延在方向の連通孔を有するシート状部材を設置した状態で加硫成型を行い、
形成された前記トレッドの表層部に、前記シート状部材を含んだ表面層を形成することを特徴とする、トレッドの形成方法。
Including a tread molding process in which unvulcanized rubber is vulcanized and molded in a mold to form a tread;
In the tread molding step, a thickness direction is formed between a tread formation portion of the unvulcanized rubber on which the tread is formed and a tread formation portion that contacts the tread formation portion of the inner surface of the mold. Vulcanization molding is performed in a state where a sheet-like member having a communication hole in the extending direction that extends across the communication hole and the communication hole in the thickness direction is installed,
A method of forming a tread, comprising forming a surface layer including the sheet-like member on a surface layer portion of the formed tread.
前記シート状部材の厚さが、0.1〜3mmであることを特徴とする、請求項1に記載の形成方法。   The forming method according to claim 1, wherein the sheet-like member has a thickness of 0.1 to 3 mm. 前記シート状部材の厚さが、0.1〜0.8mmであることを特徴とする、請求項1又は2に記載の形成方法。   The forming method according to claim 1, wherein the sheet-like member has a thickness of 0.1 to 0.8 mm. 前記トレッドが、溝と、当該溝により区画形成された陸部とを含み、
前記トレッド被形成部が、前記溝の溝底が形成される溝底被形成部と、前記陸部の側壁面が形成される側壁面被形成部と、前記陸部の踏面が形成される踏面被形成部とを備え、
前記トレッド成形工程では、前記シート状部材を、前記側壁面被形成部及び前記踏面被形成部の範囲内であって、少なくとも前記側壁面被形成部と前記踏面被形成部との境界線上を覆う位置に設置することを特徴とする、請求項1〜3のいずれか1項に記載の形成方法。
The tread includes a groove and a land portion defined by the groove,
The tread formation portion includes a groove bottom formation portion in which a groove bottom of the groove is formed, a side wall surface formation portion in which a side wall surface of the land portion is formed, and a tread on which a tread surface of the land portion is formed. A formed part,
In the tread forming step, the sheet-like member is within the range of the side wall surface formed portion and the tread surface formed portion and covers at least a boundary line between the side wall surface formed portion and the tread surface formed portion. It forms in a position, The formation method of any one of Claims 1-3 characterized by the above-mentioned.
前記トレッドが、溝と、当該溝により区画形成された陸部とを含み、
前記トレッド被形成部が、前記溝の溝底が形成される溝底被形成部と、前記陸部の側壁面が形成される側壁面被形成部と、前記陸部の踏面が形成される踏面被形成部とを備え、
前記表面層が、前記側壁面及び前記踏面の範囲内であって、少なくとも前記側壁面と前記踏面との境界線上を覆う位置に形成されることを特徴とする、請求項1〜3のいずれか1項に記載の形成方法。
The tread includes a groove and a land portion defined by the groove,
The tread formation portion includes a groove bottom formation portion in which a groove bottom of the groove is formed, a side wall surface formation portion in which a side wall surface of the land portion is formed, and a tread on which a tread surface of the land portion is formed. A formed part,
The said surface layer is in the range of the said side wall surface and the said tread surface, Comprising: It forms in the position which covers the boundary line of the said side wall surface and the said tread surface at least. 2. The forming method according to item 1.
前記シート状部材が、熱可塑性樹脂からなることを特徴とする、請求項1〜5のいずれか1項に記載の形成方法。   The forming method according to claim 1, wherein the sheet-like member is made of a thermoplastic resin. 前記シート状部材は、破断伸びが200%以上であることを特徴とする、請求項1〜6のいずれか1項に記載の形成方法。   The forming method according to claim 1, wherein the sheet-like member has an elongation at break of 200% or more. 請求項1〜7のいずれか1項に記載の形成方法によってトレッドを形成したことを特徴とする、タイヤ用プレキュアトレッド。   A tire pre-cured tread, wherein a tread is formed by the forming method according to claim 1.
JP2013091616A 2013-04-24 2013-04-24 Tread forming method and precured tread for tire Pending JP2014213506A (en)

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Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2017105405A (en) * 2015-12-11 2017-06-15 株式会社ブリヂストン tire
JP2017105406A (en) * 2015-12-11 2017-06-15 株式会社ブリヂストン Tire and method for manufacturing tire
JP2017105298A (en) * 2015-12-09 2017-06-15 株式会社ブリヂストン tire
JP2017105268A (en) * 2015-12-08 2017-06-15 株式会社ブリヂストン tire
JP2017105269A (en) * 2015-12-08 2017-06-15 株式会社ブリヂストン tire

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2017105268A (en) * 2015-12-08 2017-06-15 株式会社ブリヂストン tire
JP2017105269A (en) * 2015-12-08 2017-06-15 株式会社ブリヂストン tire
JP2017105298A (en) * 2015-12-09 2017-06-15 株式会社ブリヂストン tire
JP2017105405A (en) * 2015-12-11 2017-06-15 株式会社ブリヂストン tire
JP2017105406A (en) * 2015-12-11 2017-06-15 株式会社ブリヂストン Tire and method for manufacturing tire

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