JP4450497B2 - Pneumatic tire - Google Patents
Pneumatic tire Download PDFInfo
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- JP4450497B2 JP4450497B2 JP2000271659A JP2000271659A JP4450497B2 JP 4450497 B2 JP4450497 B2 JP 4450497B2 JP 2000271659 A JP2000271659 A JP 2000271659A JP 2000271659 A JP2000271659 A JP 2000271659A JP 4450497 B2 JP4450497 B2 JP 4450497B2
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- Prior art keywords
- air
- tire
- impermeable layer
- pneumatic tire
- thickness
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- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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Description
【0001】
【発明の属する技術分野】
本発明は、空気入りタイヤに関し、内圧保持性を損なうことなく、タイヤの重量を軽減する技術に関する。
【0002】
【従来の技術】
従来、タイヤの内圧保持のために、空気バリア層としてのインナーライナーの主原料にブチルゴム、ハロゲン化ブチルゴムなどを使用している。しかしながら、これらを配合したゴム組成物では、その空気バリア性が低いために、インナーライナーの厚さが1mm前後必要であった。このようなインナーライナーを使用すると、内圧保持のためだけに数百グラム、タイヤ重量が増加し、タイヤ軽量化の妨げとなっている。
【0003】
ところで、ブチルゴム、ハロゲン化ブチルゴムよりも空気透過性の低い材質として、多くの熱可塑性樹脂がある。例えばナイロン等の空気透過性はブチルゴムやハロゲン化ブチルゴムに比べて10分の1以下である。しかし、ナイロンは弾性率が高いため、ナイロン製のインナーライナーはタイヤ転動時の変形に追従できず、割れ等を生じ、この割れ目から空気漏れが起こり、内圧を保持できない。
また、特開平2000−177307号公報においては、エチレン・ビニルアルコール共重合体よりなる空気不透過性層を設けたことを特徴とするチューブレスタイヤについての記載がある。しかし、このエチレン・ビニルアルコール共重合体は、融点が比較的低く180℃以下となってしまうものもあり、タイヤ加硫時に溶融し、均一な空気不透過性層を得られない場合がある。また、ポリビニルアルコールは湿度の影響を受けやすく、分子設計上の物性は充分であっても、加硫温度下での強力低下などを生じることがある。
【0004】
【発明が解決しようとする課題】
本発明はインナーライナー等の内圧保持技術を改良して、タイヤの軽量化を図ることを目的とする。
【0005】
【課題を解決するための手段】
上記目的を達成するため、本発明の空気入りタイヤは以下の構成とする。
すなわち、架橋されたポリビニルアルコールまたは架橋されたエチレン・ビニルアルコール共重合体よりなる空気不透過性層を具えてなることを特徴とする。
好ましくは、前記空気不透過性層の厚さが30μm以下である。また、前記空気不透過性層に隣接して空気透過係数1.0×10-9 cm3・cm / cm2・sec・ cmHg以下のエラストマーよりなる補助層をさらに具えることを特徴とする。好ましくは、前記空気不透過性層が前記補助層に接着されてなる。また、好ましくは、前記補助層の厚さが50〜500μmである。
【0006】
【発明の実施の形態】
空気透過性を低下させるためには、ポリビニルアルコールやエチレン・ビニルアルコール共重合体[エバール(エチレン酢酸ビニル共重合体エマルジョン)から酢酸を除いて使用する]が非常に有効である。これらの(共)重合体の空気透過係数は、従来のブチル系ゴム組成物の100分の1以下であるため、内圧保持に必要な厚さは100分の1以下で足りる。
さらに、本発明で用いるポリビニルアルコールやエチレン・ビニルアルコール共重合体はポリマー分子を架橋させているため、加硫の熱がかかっても溶融することがなく、所望のタイヤ性能を確実に得ることができる。
なお、これらの(共)重合体以外にも、従来のブチル系ゴム組成物より空気透過係数の小さい樹脂は数多く存在するが、例えば空気透過性がブチル系ゴムの10分の1程度の場合、インナーライナーとして100μm前後の厚さが内圧維持のために必要となる。この厚さのフィルムは、タイヤ転動時の屈曲の変形により破断してしまう。また、タイヤ製造時にかかる伸長に追従し難い。
【0007】
これに対して、ポリビニルアルコールやエチレン・ビニルアルコール共重合体によるフィルムは、10μm程度の厚さで効果があるので、タイヤの転動時の屈曲変形による破断が生じ難くなる。この観点から空気不透過性層の厚さは30μm以下が好ましい。
ポリビニルアルコールやエチレン・ビニルアルコール共重合体は、-OH基を有するので、隣接ゴム部材との接着を比較的容易に確保できる。例えば、タイヤに使用されている不飽和系ゴム組成物との接着を確保するには、塩化ゴム・イソシアネート系の接着剤を用いればよい。一方、PVDC(ポリビニリデンクロライド)も空気不透過性樹脂として知られ、内圧保持の必要厚さを薄くできるが、本発明の樹脂と比較すると接着性が劣る。
【0008】
このように、本発明の(共)重合体は、隣接部材との接着性が良いので、たとえ、フィルムが破断しても剥離し難く、内圧保持性が高い。
上記の空気不透過性層の他に、この空気不透過性層に隣接して、この層の反空気充填側または空気充填側に、空気透過係数1.0×10-9 cm3 ・cm / cm2 ・sec・ cmHg以下のエラストマーよりなる補助層をさらに具えると好ましい。この理由は、前記空気不透過性層にピンホールやクラック等が生じた場合に、この補助層により内圧を保持するためである。このとき、空気不透過性層が補助層に接着されているほうが、剥がれ難く、空気を包むほとんどの面に空気不透過性層がそのまま存在し、内圧保持機能を発揮し続けるので好ましい。その場合の補助層の厚さは、従来のブチル系ゴムのインナーライナーの厚さ1mm程度より薄くでき、充分な重量低減が可能である。好ましくは、前記補助層の厚さが50〜500μmである。これは、50μm未満では、製造が困難であることと、たとえ製造できたとしてもガスバリアの効果が小さく、また、500μmを超えると、タイヤの重量低減効果が得られないからである。
【0009】
エチレン・ビニルアルコール共重合体中のエチレンとビニルアルコールとのモル比は特に制限されず、目的に応じて適宜設定することができる。エチレンを多くすることにより、よりタフなフィルムを得ることができ、ビニルアルコールを多くすることにより、フィルムの空気不透過性を高めることができる。
また、本発明の空気不透過性層を構成するポリビニルアルコールまたはエチレン・ビニルアルコール共重合体の架橋方法は、特に制限されないが、作製したフィルムに直接作用させ得る電子線照射法が好ましい。
【0010】
【実施例】
本発明を具体的に説明する。
空気不透過性層としてのインナーライナーを、ポリビニルアルコール(表1:PVA[(株)クラレ製、ビニロンフィルム、商標VF−A#2000])、エチレン・ビニルアルコール共重合体(表1:EVOH[(株)クラレ製、商標EF−F、融点183℃])、臭素化ブチルゴム(表1:Br−IIR、配合は表2に記載)、6−ナイロン(表1:PA6)を使用して、表1記載の厚さでそれぞれ形成し、実施例2および4にはさらに厚さ200μmの補助層(配合は表2に記載、空気透過係数2.0×10―9cm3 ・cm / cm2 ・sec・ cmHg)を設け、隣接部材との間を接着剤(東洋化学研究所製、メタロックR30M)で接着して乗用車用タイヤ(195/65R15)を試作した。
なお、実施例で使用した空気不透過性層はすべて電子線照射により架橋したものを使用し、その処理条件は加速電圧300kV、照射エネルギー20Mradであった。
【0011】
各タイヤについて、空気圧140kPaで80km/hの速度に相当する回転数のドラム上に荷重6kNで押し付けて、10,000km走行した後の内圧保持性を比較例1の値を100として指数表示し、その結果を表1に示す。また、これら各タイヤのインナーライナー外観を目視観察して、亀裂、剥離の状態を調べ、同じく表1に記載した。さらに、比較例1のタイヤ(従来タイヤ)とタイヤ重量を比較し、何%軽量化されたかをタイヤ軽量化率として表す。
【0012】
【表1】
比較例3および比較例4は、架橋していないエチレン・ビニルアルコール共重合体を使用した。タイヤ加硫後の観察により、フィルムの剥がれおよび/または穴あきが生じていたため、その後の測定を中止した。
【0013】
【表2】
【0014】
補助層がなく、空気不透過性層が剥離しない場合、内圧保持性がやや低下するが、軽量効果は大きい。補助層を加えることにより、内圧保持性を確保することができ、かつ、タイヤ軽量化効果はまだ充分に得られる。補助層が空気不透過性層に隣接し、かつ、接着しているものが望ましいと言える。
【0015】
【発明の効果】
以上説明したように、本発明によると、内圧を保持しつつ、タイヤの軽量化を図ることができる。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a pneumatic tire, and relates to a technique for reducing the weight of a tire without impairing internal pressure retention.
[0002]
[Prior art]
Conventionally, butyl rubber, halogenated butyl rubber, or the like has been used as a main raw material for an inner liner as an air barrier layer in order to maintain the internal pressure of a tire. However, in the rubber composition containing these, since the air barrier property is low, the thickness of the inner liner is required to be about 1 mm. When such an inner liner is used, the tire weight is increased by several hundred grams only for maintaining the internal pressure, which hinders weight reduction of the tire.
[0003]
By the way, there are many thermoplastic resins as materials having lower air permeability than butyl rubber and halogenated butyl rubber. For example, air permeability of nylon or the like is 1/10 or less compared to butyl rubber and halogenated butyl rubber. However, since nylon has a high modulus of elasticity, the inner liner made of nylon cannot follow the deformation at the time of rolling of the tire, causing cracks and the like, causing air leakage from the cracks, and cannot maintain the internal pressure.
Japanese Patent Application Laid-Open No. 2000-177307 discloses a tubeless tire provided with an air-impermeable layer made of an ethylene / vinyl alcohol copolymer. However, some of these ethylene / vinyl alcohol copolymers have a relatively low melting point of 180 ° C. or less, and melt at the time of tire vulcanization, so that a uniform air-impermeable layer may not be obtained. Polyvinyl alcohol is easily affected by humidity, and even if the physical properties in molecular design are sufficient, it may cause a decrease in strength at the vulcanization temperature.
[0004]
[Problems to be solved by the invention]
It is an object of the present invention to improve the internal pressure holding technology such as an inner liner to reduce the weight of a tire.
[0005]
[Means for Solving the Problems]
In order to achieve the above object, the pneumatic tire of the present invention has the following configuration.
That is, it is characterized by comprising an air-impermeable layer made of crosslinked polyvinyl alcohol or a crosslinked ethylene / vinyl alcohol copolymer.
Preferably, the air impermeable layer has a thickness of 30 μm or less. Further, an auxiliary layer made of an elastomer having an air permeability coefficient of 1.0 × 10 −9 cm 3 · cm / cm 2 · sec · cmHg or less is further provided adjacent to the air impermeable layer. Preferably, the air impermeable layer is bonded to the auxiliary layer. Preferably, the auxiliary layer has a thickness of 50 to 500 μm.
[0006]
DETAILED DESCRIPTION OF THE INVENTION
In order to reduce the air permeability, polyvinyl alcohol or an ethylene / vinyl alcohol copolymer [used by removing acetic acid from eval (ethylene vinyl acetate copolymer emulsion)] is very effective. Since the air permeability coefficient of these (co) polymers is 1/100 or less of the conventional butyl rubber composition, the thickness required for maintaining the internal pressure is 1/100 or less.
Furthermore, since the polyvinyl alcohol and the ethylene / vinyl alcohol copolymer used in the present invention cross-link polymer molecules, they do not melt even when vulcanized heat is applied, and the desired tire performance can be reliably obtained. it can.
In addition to these (co) polymers, there are many resins with a smaller air permeability coefficient than conventional butyl rubber compositions. For example, when the air permeability is about one-tenth that of butyl rubber, A thickness of around 100 μm is required for the inner liner to maintain the internal pressure. The film having this thickness is broken by bending deformation at the time of rolling of the tire. In addition, it is difficult to follow the elongation at the time of tire manufacture.
[0007]
On the other hand, a film made of polyvinyl alcohol or an ethylene / vinyl alcohol copolymer is effective at a thickness of about 10 μm, so that breakage due to bending deformation during rolling of the tire hardly occurs. From this viewpoint, the thickness of the air-impermeable layer is preferably 30 μm or less.
Since polyvinyl alcohol and ethylene / vinyl alcohol copolymer have an —OH group, adhesion to an adjacent rubber member can be secured relatively easily. For example, in order to ensure adhesion with the unsaturated rubber composition used in the tire, a chlorinated rubber / isocyanate adhesive may be used. On the other hand, PVDC (polyvinylidene chloride) is also known as an air-impermeable resin, and the required thickness for maintaining the internal pressure can be reduced, but the adhesiveness is inferior compared with the resin of the present invention.
[0008]
Thus, since the (co) polymer of the present invention has good adhesiveness with an adjacent member, even if the film breaks, it is difficult to peel off and has high internal pressure retention.
In addition to the above air impermeable layer, adjacent to the air-impermeable layer, the anti-air-filled side or air-filled side of the layer, the air permeability coefficient 1.0 × 10 -9 cm 3 · cm / cm 2 It is preferable to further provide an auxiliary layer made of an elastomer of sec · cmHg or less. The reason for this is to maintain the internal pressure by the auxiliary layer when pinholes, cracks, or the like are generated in the air impermeable layer. At this time, it is preferable that the air-impermeable layer is bonded to the auxiliary layer because the air-impermeable layer is not easily peeled off and the air-impermeable layer is present as it is on almost all surfaces enclosing air, and continues to exhibit the internal pressure holding function. In this case, the auxiliary layer can be made thinner than the conventional butyl rubber inner liner having a thickness of about 1 mm, and the weight can be sufficiently reduced. Preferably, the auxiliary layer has a thickness of 50 to 500 μm. This is because if it is less than 50 μm, it is difficult to manufacture, and even if it can be manufactured, the effect of the gas barrier is small, and if it exceeds 500 μm, the effect of reducing the weight of the tire cannot be obtained.
[0009]
The molar ratio of ethylene to vinyl alcohol in the ethylene / vinyl alcohol copolymer is not particularly limited, and can be appropriately set according to the purpose. By increasing the amount of ethylene, a tougher film can be obtained, and by increasing the amount of vinyl alcohol, the air impermeability of the film can be increased.
Moreover, the crosslinking method of the polyvinyl alcohol or ethylene / vinyl alcohol copolymer constituting the air-impermeable layer of the present invention is not particularly limited, but an electron beam irradiation method capable of directly acting on the produced film is preferable.
[0010]
【Example】
The present invention will be specifically described.
The inner liner as the air impermeable layer was made of polyvinyl alcohol (Table 1: PVA [manufactured by Kuraray Co., Ltd., vinylon film, trademark VF-A # 2000]), ethylene / vinyl alcohol copolymer (Table 1: EVOH [ (Made by Kuraray Co., Ltd., trademark EF-F, melting point 183 ° C.)), brominated butyl rubber (Table 1: Br-IIR, formulation is described in Table 2), 6-nylon (Table 1: PA6), Each of the thicknesses shown in Table 1 was formed. In Examples 2 and 4, an auxiliary layer having a thickness of 200 μm was added (the composition is shown in Table 2, air permeability coefficient 2.0 × 10 −9 cm 3 · cm 2 / cm 2 · sec A passenger car tire (195 / 65R15) was made as a trial by adhering between adjacent members with an adhesive (Metal Rock R30M, manufactured by Toyo Chemical Laboratories).
The air-impermeable layer used in the examples was all crosslinked by electron beam irradiation, and the treatment conditions were an acceleration voltage of 300 kV and an irradiation energy of 20 Mrad.
[0011]
For each tire, the internal pressure retention after being pushed by a load of 6 kN on a drum having a rotation speed corresponding to a speed of 80 km / h at an air pressure of 140 kPa and running 10,000 km is indicated as an index with the value of Comparative Example 1 being 100, The results are shown in Table 1. Further, the appearance of the inner liner of each of these tires was visually observed, and the state of cracks and peeling was examined. Furthermore, the tire weight of the tire of Comparative Example 1 (conventional tire) is compared with the tire weight, and the percentage of weight reduction is expressed as the tire weight reduction rate.
[0012]
[Table 1]
In Comparative Example 3 and Comparative Example 4, an uncrosslinked ethylene / vinyl alcohol copolymer was used. As a result of observation after vulcanization of the tire, peeling of the film and / or perforation occurred, so the subsequent measurement was stopped.
[0013]
[Table 2]
[0014]
When there is no auxiliary layer and the air-impermeable layer does not peel, the internal pressure retention is slightly reduced, but the light weight effect is great. By adding the auxiliary layer, the internal pressure retention can be ensured, and the tire weight reduction effect can still be sufficiently obtained. It may be desirable for the auxiliary layer to be adjacent to and adhered to the air impermeable layer.
[0015]
【The invention's effect】
As described above, according to the present invention, it is possible to reduce the weight of the tire while maintaining the internal pressure.
Claims (5)
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP2000271659A JP4450497B2 (en) | 2000-09-07 | 2000-09-07 | Pneumatic tire |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP2000271659A JP4450497B2 (en) | 2000-09-07 | 2000-09-07 | Pneumatic tire |
Publications (2)
Publication Number | Publication Date |
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JP2002079804A JP2002079804A (en) | 2002-03-19 |
JP4450497B2 true JP4450497B2 (en) | 2010-04-14 |
Family
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Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
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JP2000271659A Expired - Lifetime JP4450497B2 (en) | 2000-09-07 | 2000-09-07 | Pneumatic tire |
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Families Citing this family (9)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CN100491140C (en) | 2002-10-08 | 2009-05-27 | 住友橡胶工业株式会社 | Tyre without inner tube |
EP1419903B1 (en) | 2002-11-13 | 2008-05-28 | Bridgestone Corporation | Innerliner for pneumatic tires and pneumatic tire |
JP4589615B2 (en) * | 2002-11-13 | 2010-12-01 | 株式会社ブリヂストン | Inner liner for pneumatic tire and pneumatic tire |
JP2006213300A (en) * | 2005-02-07 | 2006-08-17 | Bridgestone Corp | Pneumatic tire |
WO2007037541A1 (en) | 2005-09-30 | 2007-04-05 | The Yokohama Rubber Co., Ltd. | Poorly air-permeable rubber laminate composed of poorly air-permeable resin and rubber composition, and method for production thereof |
JP5166691B2 (en) * | 2005-10-20 | 2013-03-21 | 株式会社ブリヂストン | Tire manufacturing method |
EP1974907A4 (en) * | 2006-01-17 | 2012-04-04 | Yokohama Rubber Co Ltd | Low-permeable rubber laminate and pneumatic tire using same |
JP4278697B2 (en) * | 2006-03-03 | 2009-06-17 | 横浜ゴム株式会社 | Low permeability rubber laminate and pneumatic tire using the same |
JP5754092B2 (en) | 2010-07-15 | 2015-07-22 | 横浜ゴム株式会社 | Laminated body and pneumatic tire using the same |
-
2000
- 2000-09-07 JP JP2000271659A patent/JP4450497B2/en not_active Expired - Lifetime
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