JPH0544361B2 - - Google Patents
Info
- Publication number
- JPH0544361B2 JPH0544361B2 JP61235923A JP23592386A JPH0544361B2 JP H0544361 B2 JPH0544361 B2 JP H0544361B2 JP 61235923 A JP61235923 A JP 61235923A JP 23592386 A JP23592386 A JP 23592386A JP H0544361 B2 JPH0544361 B2 JP H0544361B2
- Authority
- JP
- Japan
- Prior art keywords
- rubber
- ice
- performance
- tire
- short fibrous
- Prior art date
- 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.)
- Expired - Lifetime
Links
- 229920001971 elastomer Polymers 0.000 claims description 92
- 239000005060 rubber Substances 0.000 claims description 92
- 239000000126 substance Substances 0.000 claims description 18
- 239000002657 fibrous material Substances 0.000 description 24
- 239000000835 fiber Substances 0.000 description 20
- 239000000203 mixture Substances 0.000 description 16
- 230000000052 comparative effect Effects 0.000 description 15
- 238000004073 vulcanization Methods 0.000 description 13
- 238000000465 moulding Methods 0.000 description 11
- 238000005187 foaming Methods 0.000 description 8
- 230000000694 effects Effects 0.000 description 7
- 239000004604 Blowing Agent Substances 0.000 description 6
- PPBRXRYQALVLMV-UHFFFAOYSA-N Styrene Chemical compound C=CC1=CC=CC=C1 PPBRXRYQALVLMV-UHFFFAOYSA-N 0.000 description 6
- 239000004760 aramid Substances 0.000 description 6
- 238000000034 method Methods 0.000 description 6
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 5
- 229920003235 aromatic polyamide Polymers 0.000 description 5
- 229920001821 foam rubber Polymers 0.000 description 5
- 239000007790 solid phase Substances 0.000 description 5
- 238000005299 abrasion Methods 0.000 description 4
- 239000003795 chemical substances by application Substances 0.000 description 4
- 239000000945 filler Substances 0.000 description 4
- 239000004088 foaming agent Substances 0.000 description 4
- 239000007789 gas Substances 0.000 description 4
- 238000010438 heat treatment Methods 0.000 description 4
- 238000004519 manufacturing process Methods 0.000 description 4
- 229920002857 polybutadiene Polymers 0.000 description 4
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 4
- 244000043261 Hevea brasiliensis Species 0.000 description 3
- 230000002159 abnormal effect Effects 0.000 description 3
- 239000011324 bead Substances 0.000 description 3
- 230000007423 decrease Effects 0.000 description 3
- 238000006073 displacement reaction Methods 0.000 description 3
- 229920003052 natural elastomer Polymers 0.000 description 3
- 229920001194 natural rubber Polymers 0.000 description 3
- 229920000642 polymer Polymers 0.000 description 3
- -1 polyoxymethylene Polymers 0.000 description 3
- 230000008569 process Effects 0.000 description 3
- 238000010058 rubber compounding Methods 0.000 description 3
- 239000004576 sand Substances 0.000 description 3
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 2
- 239000004156 Azodicarbonamide Substances 0.000 description 2
- VTYYLEPIZMXCLO-UHFFFAOYSA-L Calcium carbonate Chemical compound [Ca+2].[O-]C([O-])=O VTYYLEPIZMXCLO-UHFFFAOYSA-L 0.000 description 2
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 2
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 2
- MWRWFPQBGSZWNV-UHFFFAOYSA-N Dinitrosopentamethylenetetramine Chemical compound C1N2CN(N=O)CN1CN(N=O)C2 MWRWFPQBGSZWNV-UHFFFAOYSA-N 0.000 description 2
- 239000004677 Nylon Substances 0.000 description 2
- XSQUKJJJFZCRTK-UHFFFAOYSA-N Urea Chemical compound NC(N)=O XSQUKJJJFZCRTK-UHFFFAOYSA-N 0.000 description 2
- XOZUGNYVDXMRKW-AATRIKPKSA-N azodicarbonamide Chemical compound NC(=O)\N=N\C(N)=O XOZUGNYVDXMRKW-AATRIKPKSA-N 0.000 description 2
- 235000019399 azodicarbonamide Nutrition 0.000 description 2
- 239000004202 carbamide Substances 0.000 description 2
- 239000006229 carbon black Substances 0.000 description 2
- 238000013329 compounding Methods 0.000 description 2
- 239000006185 dispersion Substances 0.000 description 2
- 238000011156 evaluation Methods 0.000 description 2
- 238000001125 extrusion Methods 0.000 description 2
- 230000009477 glass transition Effects 0.000 description 2
- VKYKSIONXSXAKP-UHFFFAOYSA-N hexamethylenetetramine Chemical compound C1N(C2)CN3CN1CN2C3 VKYKSIONXSXAKP-UHFFFAOYSA-N 0.000 description 2
- 125000001570 methylene group Chemical group [H]C([H])([*:1])[*:2] 0.000 description 2
- 238000002156 mixing Methods 0.000 description 2
- 229920001778 nylon Polymers 0.000 description 2
- 229920001195 polyisoprene Polymers 0.000 description 2
- 230000002787 reinforcement Effects 0.000 description 2
- GHMLBKRAJCXXBS-UHFFFAOYSA-N resorcinol Chemical compound OC1=CC=CC(O)=C1 GHMLBKRAJCXXBS-UHFFFAOYSA-N 0.000 description 2
- GOOMUPCAOADBSA-UHFFFAOYSA-N 1-n,2-n-dimethyl-1-n,2-n-dinitrosobenzene-1,2-dicarboxamide Chemical compound O=NN(C)C(=O)C1=CC=CC=C1C(=O)N(C)N=O GOOMUPCAOADBSA-UHFFFAOYSA-N 0.000 description 1
- NBOCQTNZUPTTEI-UHFFFAOYSA-N 4-[4-(hydrazinesulfonyl)phenoxy]benzenesulfonohydrazide Chemical compound C1=CC(S(=O)(=O)NN)=CC=C1OC1=CC=C(S(=O)(=O)NN)C=C1 NBOCQTNZUPTTEI-UHFFFAOYSA-N 0.000 description 1
- ATRRKUHOCOJYRX-UHFFFAOYSA-N Ammonium bicarbonate Chemical compound [NH4+].OC([O-])=O ATRRKUHOCOJYRX-UHFFFAOYSA-N 0.000 description 1
- 229910000013 Ammonium bicarbonate Inorganic materials 0.000 description 1
- 229930040373 Paraformaldehyde Natural products 0.000 description 1
- 239000005062 Polybutadiene Substances 0.000 description 1
- 239000004793 Polystyrene Substances 0.000 description 1
- 229920000297 Rayon Polymers 0.000 description 1
- UIIMBOGNXHQVGW-DEQYMQKBSA-M Sodium bicarbonate-14C Chemical compound [Na+].O[14C]([O-])=O UIIMBOGNXHQVGW-DEQYMQKBSA-M 0.000 description 1
- 229910000831 Steel Inorganic materials 0.000 description 1
- 229920002978 Vinylon Polymers 0.000 description 1
- VRFNYSYURHAPFL-UHFFFAOYSA-N [(4-methylphenyl)sulfonylamino]urea Chemical compound CC1=CC=C(S(=O)(=O)NNC(N)=O)C=C1 VRFNYSYURHAPFL-UHFFFAOYSA-N 0.000 description 1
- RAVCBGFXQNUHOI-UHFFFAOYSA-N [[6-amino-4-(dimethylamino)-1,2,3,4-tetramethyl-1,3,5-triazin-2-yl]-methoxyamino]methanol Chemical compound CN(C1(N(C(N(C(=N1)N)C)(N(CO)OC)C)C)C)C RAVCBGFXQNUHOI-UHFFFAOYSA-N 0.000 description 1
- 239000000853 adhesive Substances 0.000 description 1
- 230000001070 adhesive effect Effects 0.000 description 1
- 230000002411 adverse Effects 0.000 description 1
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 1
- 235000012538 ammonium bicarbonate Nutrition 0.000 description 1
- 239000001099 ammonium carbonate Substances 0.000 description 1
- 230000003712 anti-aging effect Effects 0.000 description 1
- 239000002216 antistatic agent Substances 0.000 description 1
- 229920006231 aramid fiber Polymers 0.000 description 1
- 230000004888 barrier function Effects 0.000 description 1
- 230000008901 benefit Effects 0.000 description 1
- LSNDGFYQJRXEAR-UHFFFAOYSA-N benzenesulfonamidourea Chemical compound NC(=O)NNS(=O)(=O)C1=CC=CC=C1 LSNDGFYQJRXEAR-UHFFFAOYSA-N 0.000 description 1
- VJRITMATACIYAF-UHFFFAOYSA-N benzenesulfonohydrazide Chemical compound NNS(=O)(=O)C1=CC=CC=C1 VJRITMATACIYAF-UHFFFAOYSA-N 0.000 description 1
- 229920005549 butyl rubber Polymers 0.000 description 1
- 229910000019 calcium carbonate Inorganic materials 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 239000001569 carbon dioxide Substances 0.000 description 1
- 229910002092 carbon dioxide Inorganic materials 0.000 description 1
- 239000004927 clay Substances 0.000 description 1
- 229910052570 clay Inorganic materials 0.000 description 1
- 239000003086 colorant Substances 0.000 description 1
- 229920001577 copolymer Polymers 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 238000005520 cutting process Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 239000000428 dust Substances 0.000 description 1
- HQQADJVZYDDRJT-UHFFFAOYSA-N ethene;prop-1-ene Chemical group C=C.CC=C HQQADJVZYDDRJT-UHFFFAOYSA-N 0.000 description 1
- 239000010408 film Substances 0.000 description 1
- 238000009472 formulation Methods 0.000 description 1
- 239000011521 glass Substances 0.000 description 1
- PCHJSUWPFVWCPO-UHFFFAOYSA-N gold Chemical compound [Au] PCHJSUWPFVWCPO-UHFFFAOYSA-N 0.000 description 1
- 239000010931 gold Substances 0.000 description 1
- 229910052737 gold Inorganic materials 0.000 description 1
- 229910002804 graphite Inorganic materials 0.000 description 1
- 239000010439 graphite Substances 0.000 description 1
- 239000004312 hexamethylene tetramine Substances 0.000 description 1
- 235000010299 hexamethylene tetramine Nutrition 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 239000012784 inorganic fiber Substances 0.000 description 1
- 229910010272 inorganic material Inorganic materials 0.000 description 1
- 239000011147 inorganic material Substances 0.000 description 1
- 230000014759 maintenance of location Effects 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 239000002923 metal particle Substances 0.000 description 1
- 229910052757 nitrogen Inorganic materials 0.000 description 1
- 230000003287 optical effect Effects 0.000 description 1
- 239000011368 organic material Substances 0.000 description 1
- RGSFGYAAUTVSQA-UHFFFAOYSA-N pentamethylene Natural products C1CCCC1 RGSFGYAAUTVSQA-UHFFFAOYSA-N 0.000 description 1
- 229920002589 poly(vinylethylene) polymer Polymers 0.000 description 1
- 229920000728 polyester Polymers 0.000 description 1
- 229920006324 polyoxymethylene Polymers 0.000 description 1
- 229920002223 polystyrene Polymers 0.000 description 1
- 239000002964 rayon Substances 0.000 description 1
- 238000011084 recovery Methods 0.000 description 1
- 239000012744 reinforcing agent Substances 0.000 description 1
- 238000013040 rubber vulcanization Methods 0.000 description 1
- HBMJWWWQQXIZIP-UHFFFAOYSA-N silicon carbide Chemical compound [Si+]#[C-] HBMJWWWQQXIZIP-UHFFFAOYSA-N 0.000 description 1
- 229910010271 silicon carbide Inorganic materials 0.000 description 1
- 239000000377 silicon dioxide Substances 0.000 description 1
- 230000003068 static effect Effects 0.000 description 1
- 239000010959 steel Substances 0.000 description 1
- 239000003351 stiffener Substances 0.000 description 1
- 230000002195 synergetic effect Effects 0.000 description 1
- 229920003051 synthetic elastomer Polymers 0.000 description 1
- 239000005061 synthetic rubber Substances 0.000 description 1
- 229920001897 terpolymer Polymers 0.000 description 1
- 238000010998 test method Methods 0.000 description 1
- 239000010409 thin film Substances 0.000 description 1
- 125000005147 toluenesulfonyl group Chemical group C=1(C(=CC=CC1)S(=O)(=O)*)C 0.000 description 1
- UONOETXJSWQNOL-UHFFFAOYSA-N tungsten carbide Chemical compound [W+]#[C-] UONOETXJSWQNOL-UHFFFAOYSA-N 0.000 description 1
- KAKZBPTYRLMSJV-UHFFFAOYSA-N vinyl-ethylene Natural products C=CC=C KAKZBPTYRLMSJV-UHFFFAOYSA-N 0.000 description 1
Landscapes
- Tires In General (AREA)
- Manufacture Of Porous Articles, And Recovery And Treatment Of Waste Products (AREA)
- Tyre Moulding (AREA)
Description
（産業上の利用分野）
本発明は空気入りタイヤ、詳しくは、耐摩耗性
能、操縦安定性能及び乗心地性能等を十分に維持
したまま、湿潤路面に対して、それも特に低温時
においても十分に高い摩擦抵抗を有するような氷
上制動性能が優れた、特に寒冷地での使用に適し
た空気入りタイヤに関するものである。
（従来の技術）
空気入りタイヤの氷雪路面、特に氷上での滑り
抵抗性を改良するために、トレツドゴム中に砂、
金鋼砂、金属粒等の充填材を混入することは既知
である。
しかしながら、充填材の混入を多くしないと効
果があらわれ難い反面、多量の混入は却つてトレ
ツド部の耐摩耗性を著しく害し、また、ゴムの硬
度が増加するため乗心地を悪化させてしまうとい
う大きな問題があつた。
また、短繊維をゴム成型品中に配合し、ゴムの
硬度を上げずにゴムの耐カツト性、耐亀裂成長性
を向上させることもすでに知られているが、この
ような短繊維を配合したゴムシート等のゴム成型
品は通常、ゴム成型品の製造時にロール等により
シート状にのされたり或いは押出機で押し出され
たりするため、未加硫段階でのゴム加工工程にお
いて短繊維２０（第３図には模擬的に線で示され
ている。）が第３図に示すように、押し出し方向
Ｐにほぼ一定に並んで配向し、加熱下での加硫成
型中もこの配向はほぼそのまま維持されることに
なる。
従つて、このように短繊維が一定の方向に配向
したゴム成型品２１は力学的特性等に大きな異方
性を生じることになる。例えば、短繊維の配向方
向Ａには弾性率が大きく増加しても、該配向方向
と直交する方向Ｂでの増加はわずかである。
このように力学的特性等に大きな異方性のある
成型品を空気入りタイヤのトレツド部に使用する
と、チツピング（鱗片状剥離）あるいは偏摩耗等
の異常摩耗の原因となつたり、操縦性能等に悪影
響を及ぼすことになるので、特に空気入りタイヤ
のトレツド部においては力学的特性に異方性が生
じないことが重要である。
従つて、このような異方性をなくすために、や
むなく上記のような短繊維が一定の方向に配向し
たゴムシート等の成型品の複数を、短繊維の配向
方向が全体として種々の方向に向くように積層し
て生タイヤを成型しなければならず、そのために
成型工程数が著しく増加し、空気入りタイヤの生
産性が悪化するという問題があつた。
一方、独立気泡を有する発泡ゴムをトレツド部
に用いたタイヤについては、例えば特公昭40−
4641号公報、米国特許第4249588号明細書、更に
は特開昭６−154304号公報等で提案されている。
しかし、特公昭40−4641号公報に開示されてい
る多孔質トレツドを備えた辷止めタイヤにおいて
は、ヒステリシスロスの大きい合成ゴム、例えば
ハイスチレンゴムが用いられているので、低温に
なるとゴムの硬度が増すことから氷雪路面上を走
行する際の駆動性、制動性及び操縦性（以下、単
に、「氷雪性能」という。）を確保する上で好まし
くない。
また、米国特許第4249588号明細書に開示され
ているタイヤは、オフ・ザ・ロードやゴルフカー
ト等のタイヤ性能を改良したものではあるが、氷
雪性能に関しては全く触れられていない。
更に、特開昭56−154304号公報には発泡ゴムを
用いて非発泡ゴムと同じ硬さを得るようにした軽
量タイヤについて教示されているが、やはり氷雪
性能には全く触れられていない。
以上述べたように、空気入りタイヤにおいて、
短繊維によるゴムの補強と発泡ゴムの利用とは、
それぞれ、別々には、いずれも公知の技術ではあ
るが、本発明のように、トレツド部を無配向に分
散された短繊維状物質及び分散された独立気泡を
有する発泡ゴム層で形成することによつて、無配
向に分散された短繊維状物質と独立気泡との相乗
により、耐摩耗性能、操縦安定性能及び乗心地性
能等について従来の空気入りタイヤの一般的水準
を十分に維持したまま、更に、氷上制動性能等を
向上させることについては、従来の技術にその開
示を見出すことが出来ないものである。
〔発明が解決しようとする課題〕
従来、氷雪路面上を走行する空気入りタイヤの
氷雪性能を確保するために専らスパイクピンが用
いられたところ、スパイクピンによる粉塵公害や
路面の損傷のため、その使用が制限され、そこ
で、所謂、スタツドレスタイヤがスパイクピンを
有するタイヤに変わつて使用されるようになつた
が、上述したように実用的に十分満足しうるもの
ではない。
本発明の目的は、耐摩耗性能や操縦安定性能並
びに乗心地性能について従来のタイヤの一般的水
準を十分に維持したまま、湿潤路面に対して、特
に低温時においても高に摩擦抵抗をもたらして氷
上制動性能が優れ、しかも成型加工時の工程数を
減少させることにより生産性をも高めることがで
きる、特に寒冷地での使用に適した空気入りタイ
ヤを提供することにある。
（課題を解決するための手段）
本発明は、上記の目的を達成するために、タイ
ヤのケースとケースのクラウン部を被覆するトレ
ツド部とを備えた空気入りタイヤのトレツド部
に、無配向に分散された短繊維状物質及び分散さ
れた独立気泡を有する発泡ゴム層を適用したもの
であり、そして、特にトレツド部を形成するゴム
組成物中に配合された短繊維状物質が、加熱下で
の加硫成型中に、トレツド部における独立気泡の
生産に伴い変位させた無配向に分散されることを
利用したものである。
短繊維状物質及び発泡剤を配合したゴム組成物
について、加熱下での加硫成型時における気泡の
発生及び成長とこれに伴う短繊維状物質の無配向
分散物向、ゴム弾性率の変化及び低温時の摩擦係
数等につき発明者らが種々研究した結果の概要は
次の通りである。
先ず、上記のような短繊維状物質及び発泡剤を
配合したゴム組成物にあつては、加熱下での加硫
成型時に、発泡剤が分解して発生するガスにより
ゴム内に独立気泡が生成され、その際に事前の押
し出し加工等に由来した短繊維状物質のほぼ一定
方向の配向が大きく乱されるということを見出
し、かくしてたらされる短繊維状物質の発泡ゴム
層における無配向分散から生じる有用性を、特に
寒冷地での使用に適するように空気入りタイヤの
トレツド部に適用することが本発明の基本の構想
である。
しかも、無配向に分散された短繊維状物質と分
散された独立気泡を有する発泡ゴム層を空気入り
タイヤのトレツド部に適用することにより、トレ
ツドゴム表面は微細な凹凸形状になり、その結
果、湿潤路面及び氷上での摩擦係数が高くなりタ
イヤのグリツプ性が向上することになり、また、
トレツドゴムの弾性率が高くなることから空気入
りタイヤの操縦性能、特にコーナリングパワーの
増大が図れる。
ここで、トレツドゴムとして使用する原料ゴム
としては、例えば、天然ゴム、ポリイソプレンゴ
ム、ポリブタジエンゴム、ポリスチレンブタジエ
ンゴム、エチレン・プロピレンターポリマー、ポ
リブチルゴム等があげられるが、これらに何ら限
定されるものではない。
空気入りタイヤの乗心地性能及び操縦安定性能
等を損なうことなく氷上制動性能等を更に改良し
ようとする場合には、トレツドゴムは低温時にお
いても十分にゴム弾性を有するガラス転移温度−
60℃以下の重合物のゴム成分を含有することが好
ましい。ガラス転移温度−60℃以下の重合物とし
ては、例えば、天然ゴム、ポリイソプレンゴム、
ポリブタジエンゴム、ブチルゴム、低スチレン含
有のスチレン、ブタジエン共重合ゴムの独立、又
は、これらの重合物の２種以上の混合物が好まし
い。
本発明で用いるゴム組成物のゴム配合に必須の
成分の一つは短繊維状物質であり、もう一つは発
泡剤である。
発泡剤は、生タイヤを加硫成型する際の加熱に
より分解して独立気泡を生成し、これにより短繊
維状物質が無配向に分散された発泡ゴム層が形成
される。
ここに、短繊維状物質としては短繊維が一般的
であるが棒状又は針状の有機又は無機物質でもよ
い。例えば、芳香族ポリアミド（アラミド）、ビ
ニロン、ポリエステル、ナイロン、レーヨンなど
の有機繊維をカツトしたもの、シンジオタクチツ
ク−１，２−ポリブタジエンの針状結晶、ポリオ
キシメチレンのウイスカー等の有機物質や、シリ
コンカーバイト、タングステンカーバイト、アル
ミナ等の無機物質のウイスカー等及びガラス、炭
素、黒鉛、金属等の無機繊維をカツトしたものが
あげられるが、しかし、これらのみに限定される
ものではない。
次に、発泡剤としては、、例えば、二酸化炭素
を発生する重炭酸アンモニウム、重炭酸ナトリウ
ム及び窒素を発生するニトロソスルホニルアゾ化
合物、例えば、ジニトロソペンタメチレンテトラ
ミン、Ｎ，N′−ジメチル−Ｎ，N′−ジニトロソ
フタルアミド、アゾジカ−ボンアミド、Ｎ，
N′−ジニトロソペンタメチレンテトラミン、ベ
ンゼンスルホニルヒドラジド、トルエンスルホニ
ルヒドラジド、Ｐ，P′−オキシ−ビス（ベンゼン
スルホニルヒドラジド）、Ｐ−トルエンスルホニ
ルセミカルバジド、Ｐ，P′−オキシ−ビス（ベン
ゼンスルホニルセミカルバジド）等があげられ、
加硫温度に応じてこれらを適宜に選択して使用す
る。また、発泡助剤としては尿素等が挙げられ
る。
本発明の発泡ゴム層のゴム配合には、上述した
必須の配合成分の他に、ゴム補強のためのカーボ
ンブラツクや、シリカ、炭酸カルシウム、クレー
等の充填材等も適宜選択して使用することができ
る。
その他の配合剤として、軟化剤、加硫剤、加硫
促進剤、加硫助剤、老化防止剤、場合により着色
剤、帯電防止剤、或いは、短繊維状物質とゴムと
の接着性を増大させる接着成分、例えば、レゾル
シンのようなメチレンアクセプターとヘキサメチ
レンテトラミン、ヘキサメチルメトキシメチロー
ルメラミンのようなメチレンドナーとを配合する
等慣用により適宜添加される。
上記のような短繊維状物質及び発泡剤を含有
し、かつ、カーボンブラツクのような補強剤、加
硫促進剤等の通常のゴム配合剤を適宜配合したゴ
ム組成物を、加圧加硫すると、熱により発泡剤が
分散してゴム中に独立気泡を生成しながらゴムの
加硫が進行する。この独立気泡の生成により、ゴ
ム組成物中に配合分散された短繊維状物質が変位
を起こし、その配向が乱され無配向に分散される
ことになる。
次いで、ゴムの加硫成型が終了すると、発泡ゴ
ムは成型圧力から開放されるので、独立気泡はそ
の内部圧力により膨張し大きくなり、短繊維状物
質の更なる変位が起こり、短繊維状物質の無配向
化が更に促進されることになる。
また、このように加硫成型後にゴム中の独立気
泡が大きくなると、このためにゴムは歪みを受け
るので、短繊維状物質はこのゴムの歪み方向に張
力を受けることになり、従つて、短繊維状物質で
補強された発泡ゴム層の弾性率は更に高められる
ことになる。
上記のように、短繊維状物質が無配向に分散さ
れた発泡ゴム層を有するトレツド部は、その弾性
率が単に発泡ゴムよりなるものよりも高く、空気
入りタイヤの操縦性能、特にコーナリングパワー
の増大に有利で、しかも異方性に起因する上述し
た異常摩耗を防ぐことができ耐摩耗性能の向上に
とつても有利である。
そして、無配向に分散された短繊維状物質と分
散された独立気泡とにより、トレツドゴムの表面
は微細な凹凸形状を有するゴム表面となるので、
湿潤な路面及び氷上での摩擦係数が高くなり、タ
イヤのグリツプ性能等が著しく向上する。
特に、上記の独立気泡によつてトレツド部に形
成される多くの凹部が、配合された短繊維状物質
による微細な凹凸と相まつて、氷雪路でタイヤが
滑る大きな原因となる路面との間の水膜を排除す
るため、より強力なグリツプが得られるととも
に、更に、この凹部がエツジ効果を発揮するの
で、トラクシヨン性能及びブレーキ性能も大幅に
向上する。このため、特に、アイスバーンの表面
を薄く水膜が覆つた状態、所謂、ウエツト・オ
ン・アイスでの制動性能等が大幅に向上する。
そして、この無配向に分散された短繊維状物質
と分散された独立気泡は、タイヤが摩耗しても
次々に新たに路面と接するトレツド部表面に現わ
れるので、上記の性能が持続されることになる。
ところで、ゴム組成物に混入される短繊維状物
質は平均長さ５〜5000μmが好ましく、そして、
その平均直径の10〜1000倍の平均長さを有するこ
とが発泡に起因する短繊維状物質の効果的な無配
向化に際し好ましい。
また、発泡ゴム層の独立気泡のの平均気泡径は
10〜300μmが望ましく、好ましくは30〜150μmで
ある。発泡ゴム層の気泡径は10〜300μmとしたの
は、10μm未満では短繊維状物質の無配向化の効
果が充分に得られず、また、300μmを超えると耐
摩耗性が低下し、更に、発泡ゴム層の歪み回復力
が低下し、所謂、耐ヘタリ性が悪化したり、製造
時においてもパーマネントセツト性の低下により
安定した形状を得ることが困難となるからであ
る。
また、発泡率は次式
Vs＝｛（p0−p9）／（p1−p9）−１｝×100％ …(1)
で表され、p1は発泡ゴム層の密度（ｇ／cm3）、
p0は発泡ゴム層の固相部の密度（ｇ／cm3）、p0
は発泡ゴム層のガスの密度（ｇ／cm3）である。発
泡ゴム層はゴム固相部と、ゴム固相部によつて形
成される空洞（独立気泡）、即ち、気泡内のガス
部とから構成されている。
ガス部の密度p0は極めて小さく、ほぼ零に近
く、かつ、ゴム固相部の密度p1に対して極めて小
さいので式(1)は、次式
Vs＝（p0／p1−１）×100％ …(2)
とほぼ同等となる。
ここで発泡率Vsは５〜50％の範囲が望ましく、
好ましくは５〜30％であり、更に好ましくは10〜
30％である。発泡率Vsを５％以上としたのは、
５％未満では氷雪性能の改良効果が比較的少ない
ためである。また、50％を超えると、氷上性能の
向上が少ない割りには、氷雪路面、湿潤路面以外
の乾燥路面での耐摩耗性能の面で不利となる。
また、短繊維状物質が無配向に分散された発泡
ゴム層は、トレツド部の全体積の少なくとも10％
存在することが望ましく、好ましくは10〜70％、
更に好ましくは40〜60％である。発泡ゴム層をト
レツド部の全体積の少なくとも10％以上としたの
は、10％未満では氷雪性能の改良効果が少ないた
めである。また、氷雪性能を長期間にわたつて持
続させたい場合には、当然のことながら、トレツ
ド部全体をこのような発泡ゴムで構成することが
好ましい。
（実施例）
以下に、本発明を実施例に基づいて説明する。
表１及び表２にはゴム組成物の配合割合（単
位：重量部）、ゴム組成物の性質或いは本発明の
無配向に分散された短繊維状物質と分散された独
立気泡を有する発泡ゴム層をトレツド部に適用し
た空気入りタイヤの性能等が示されている。
ゴム組成物は、ゴム成分として天然ゴム及びポ
リブタジエンゴム等を含み、発泡剤としてジニト
ロンペンタメチレンテトラミン、アゾジカーボン
アミド及び尿素（発泡助剤）を適宜使用し、短繊
維状物質として、実施例１〜５においてはアラミ
ド短繊維（平均長さ5μm、平均直径0.2μm）或い
は実施例６においてはナイロン短繊維（平均長さ
10μm、平均直径0.4μm）を適宜混入分散した。
具体的には、実施例１〜５のゴム組成物は本発
明に規定する好ましい範囲をそれぞれ満たした配
合であり、比較例１及び２は独立気泡及びアラミ
ド短繊維を共に含まない例であり、また比較例３
及び４は独立気泡を有するが、アラミド短繊維を
含まない例であり、更に比較例５はアラミド短繊
維を含むが独立気泡を有しない例であり、それぞ
れ本発明の各実施例との比較を行つた。
また、実施例６は、本発明に係る発泡ゴム組成
物を空気入りタイヤのトレツド部に用い、湿潤コ
ンクリート路面における制動性能の向上を図つた
ものであり、比較例６は、実施例６においてナイ
ロン短繊維を除いた組成物を用いて実施例６と同
様に製造したものである。
各試験方法は、以下の通りである。
(1) 平均気泡径及び発泡率Vs
平均気泡径は試験タイヤのトレツドゴム（発泡
ゴム）からブロツク状の試料を切り出し、その試
料断面の写真を倍率100〜400倍の光学顕微鏡で撮
影し、200個以上の独立気泡の気泡直径を測定し、
算術平均値として表した。
また、発泡率Vsはブロツク状の前記試料の密
度p1（ｇ／cm3）を測定し、一方、無発泡ゴム（固
相ゴム）のトレツド部の密度p0を測定し、前記式
(2)を用いて求めた。
(2) 硬度及び50％伸張時の引張応力
試験タイヤのトレツドゴムからブロツク状の試
料を切り出し、硬さはJIS硬度計でJIS K6301に
準じて測定した。また、50％伸張時の引張応力は
万能引張試験機でJIS K6301に準じて行つた。
(3) 耐摩耗性能
ピコ式摩耗試験機を用い、ASTM D2228に準
拠して実施し、指数表示した。数値は大きいほど
良いことを示す。
(4) 氷上摩擦係数
トレツドゴムの氷上摩擦係数、特に０℃付近の
湿潤状態における氷上の摩擦係数は、表面温度が
−0.5℃の氷上に発泡ゴム層から切り出した試料
の表面（試料寸法：長さ10mm、幅10mm、厚さ５
mm）を接触させ、協和界面科学(株)製の動・静摩擦
係数計を用いて測定した。測定条件として荷重２
Kg／cm3、滑り速度10mm／sec、零囲気温度−２℃、
氷表面はほぼ鏡面状態で行つた。
(5) 操縦安定性能及び乗心地性能
各実施例または各比較例のタイヤを、排気量
1500c.c.の乗用車に装着し、テストコースのコンク
リート路面上を所定の速度で走行し、フイーリン
グ試験を行い平均した。評価は10点評価法により
比較例１のタイヤをコントロール（基準）として
表示した。＋（プラス）印は良好なこと、−（マイナ
ス）印は不良なことを示す。
(6) 氷上制動性能
各試験タイヤ４本を排気量1500c.c.の乗用車に装
着し、外気温−５℃、時速20Kmで氷上における制
動距離を測定した。無発泡タイヤ（比較例１）の
場合を100として指数表示した。数値は小さいほ
ど制動性能が良好であることを示す。
上記の空気入りタイヤの具体的構成は、以下の
通りである。
即ち、第１図に示すように、空気入りタイヤ１
は、タイヤのケース２及びケース２のクラウン部
２ａを被覆する無配向に分散された短繊維状物質
と分散された独立気泡を有する発泡ゴム層１５を
有するトレツド部３とを具備している。ケース２
は、一対のビード部５と、ビード部５間にほぼ放
射方向に配置したゴム引きのコードからなるカー
カス部６と、カーカス部６のクラウン部２ａに円
周方向に配置したベルト部７及びカーカス部６の
側部を被覆するサイドウオールゴム８とから構成
されている。
なお、９はステイフナーゴムであり、３ａはト
レツド部の表面を表す。また、トレツド部３以外
の構成は通常の空気入りタイヤと同じである。そ
して、この空気入りタイヤの製造方法は通常のタ
イヤと同じであり、この製造時に、前述したよう
に、未加硫のゴム組成物は、加熱下での加圧、加
硫時に発泡剤が分解してゴム内に独立気泡のを生
じ、短繊維状物質を無配向化し、更に、加硫終了
後の減圧により短繊維状物質の無配向化が更に促
進されるとともに、短繊維状物質がゴムの歪み方
向に張力を受けて発泡ゴム層の弾性率を更に高め
ることになる。
短繊維状物質を無配向に分散させた発泡ゴム層
１５よりなるトレツド部３の断面が第２図に示め
されている。図２に示されているように、分散さ
れた独立気泡１１（図には丸印にて示されてい
る。）を有する発泡ゴム層中に短繊維状物質１２
が無配向に分散されている。
(Industrial Application Field) The present invention relates to a pneumatic tire, in particular, a pneumatic tire that can withstand wet road surfaces, particularly at low temperatures, while maintaining sufficient wear resistance performance, handling stability performance, ride comfort performance, etc. The present invention relates to a pneumatic tire that has excellent braking performance on ice, such as high frictional resistance, and is particularly suitable for use in cold regions. (Prior art) In order to improve the slip resistance of pneumatic tires on icy and snowy roads, especially on ice, sand and sand are added to the tread rubber.
It is known to incorporate fillers such as gold steel sand and metal particles. However, while it is difficult to see any effect unless a large amount of filler is mixed in, mixing a large amount of filler can actually seriously impair the wear resistance of the tread area, and also increase the hardness of the rubber, resulting in a worsening of riding comfort. There was a problem. It is also already known that short fibers can be blended into rubber molded products to improve the cut resistance and crack growth resistance of the rubber without increasing the hardness of the rubber. Rubber molded products such as rubber sheets are usually rolled into a sheet shape using rolls or extruded during the production of rubber molded products, so short fibers 20 (No. (indicated by lines in Fig. 3) are oriented almost uniformly in the extrusion direction P as shown in Fig. 3, and this orientation remains almost unchanged even during vulcanization molding under heating. It will be maintained. Therefore, the rubber molded product 21 in which short fibers are oriented in a certain direction will exhibit large anisotropy in mechanical properties and the like. For example, even if the elastic modulus increases greatly in the orientation direction A of short fibers, the increase in the direction B orthogonal to the orientation direction is small. If a molded product with large anisotropy in mechanical properties is used in the tread part of a pneumatic tire, it may cause abnormal wear such as chipping (scaly peeling) or uneven wear, and may affect handling performance, etc. It is important that anisotropy does not occur in the mechanical properties, especially in the tread portion of a pneumatic tire, as this would have an adverse effect. Therefore, in order to eliminate such anisotropy, it is necessary to make a plurality of molded products such as rubber sheets in which short fibers are oriented in a certain direction as described above, so that the short fibers are oriented in various directions as a whole. A green tire must be molded by stacking the layers so that they face each other, which significantly increases the number of molding steps, resulting in a problem that the productivity of pneumatic tires deteriorates. On the other hand, for tires using foamed rubber with closed cells in the tread part, for example,
This method has been proposed in Japanese Patent No. 4641, US Pat. No. 4,249,588, and Japanese Patent Application Laid-Open No. 154304/1984. However, in the anti-slip tire with a porous tread disclosed in Japanese Patent Publication No. 40-4641, synthetic rubber with a large hysteresis loss, such as high styrene rubber, is used. This is undesirable in terms of ensuring driving performance, braking performance, and maneuverability (hereinafter simply referred to as "ice and snow performance") when driving on ice and snow roads. Further, although the tire disclosed in US Pat. No. 4,249,588 has improved tire performance for off-the-road and golf carts, it does not mention ice and snow performance at all. Further, JP-A-56-154304 teaches a lightweight tire that uses foamed rubber to achieve the same hardness as non-foamed rubber, but it does not mention ice and snow performance at all. As mentioned above, in pneumatic tires,
What is the reinforcement of rubber with short fibers and the use of foam rubber?
Each of these techniques is known separately, but as in the present invention, the tread portion is formed of a foamed rubber layer having non-oriented short fibrous material and dispersed closed cells. Therefore, due to the synergistic effect of the short fibrous material dispersed in a non-oriented manner and the closed cells, the tire maintains the general standards of conventional pneumatic tires in terms of wear resistance, handling stability, riding comfort, etc. Furthermore, there is no disclosure in the prior art regarding improving braking performance on ice. [Problem to be solved by the invention] Conventionally, spike pins were exclusively used to ensure the ice and snow performance of pneumatic tires running on icy and snowy roads, but due to the dust pollution and damage to the road surface caused by the spike pins, Their use has been limited, and so-called studless tires have come to be used instead of tires with spike pins, but as mentioned above, they are not fully satisfactory from a practical standpoint. The object of the present invention is to provide high frictional resistance on wet road surfaces, especially at low temperatures, while sufficiently maintaining the general standards of conventional tires in terms of wear resistance, handling stability, and ride comfort. To provide a pneumatic tire that has excellent braking performance on ice, can also increase productivity by reducing the number of molding steps, and is particularly suitable for use in cold regions. (Means for Solving the Problems) In order to achieve the above-mentioned object, the present invention provides a pneumatic tire having a tire case and a tread portion covering the crown portion of the case. A foamed rubber layer having a dispersed short fibrous material and dispersed closed cells is applied, and in particular, the short fibrous material blended into the rubber composition forming the tread portion is heated. This method takes advantage of the fact that during vulcanization molding, closed cells are produced in the tread portion and are displaced and dispersed in a non-oriented manner. Regarding rubber compositions containing short fibrous substances and foaming agents, generation and growth of bubbles during vulcanization molding under heating, and accompanying changes in non-oriented dispersion of short fibrous substances, changes in rubber elastic modulus, and A summary of the results of various studies conducted by the inventors regarding the coefficient of friction at low temperatures is as follows. First, in the case of a rubber composition containing a short fibrous substance and a blowing agent as described above, closed cells are generated in the rubber by the gas generated when the blowing agent decomposes during vulcanization molding under heating. It was discovered that during this process, the almost constant orientation of the short fibrous material derived from the prior extrusion process etc. was greatly disturbed, and it was found that the non-oriented dispersion of the resulting short fibrous material in the foamed rubber layer. It is the basic idea of the invention to apply the resulting utility to the tread section of a pneumatic tire in a way that makes it particularly suitable for use in cold regions. Furthermore, by applying a foamed rubber layer containing non-oriented short fibrous substances and dispersed closed cells to the tread portion of a pneumatic tire, the tread rubber surface becomes microscopically uneven, resulting in moisture retention. The coefficient of friction on the road and ice increases, improving the grip of the tire, and
Since the elastic modulus of the tread rubber is increased, the handling performance of the pneumatic tire, especially the cornering power, can be increased. Here, raw rubber used as the tread rubber includes, for example, natural rubber, polyisoprene rubber, polybutadiene rubber, polystyrene butadiene rubber, ethylene-propylene terpolymer, polybutyl rubber, etc., but is not limited to these in any way. do not have. When trying to further improve the on-ice braking performance, etc. of pneumatic tires without impairing the ride comfort, handling stability, etc., tread rubber has a glass transition temperature - - which has sufficient rubber elasticity even at low temperatures.
It is preferable to contain a rubber component of a polymer having a temperature of 60°C or less. Examples of polymers with a glass transition temperature of -60°C or lower include natural rubber, polyisoprene rubber,
Polybutadiene rubber, butyl rubber, styrene with low styrene content, and butadiene copolymer rubber may be used individually, or a mixture of two or more of these polymers is preferred. One of the essential components for the rubber compounding of the rubber composition used in the present invention is a short fibrous substance, and the other is a blowing agent. The foaming agent is decomposed by heating during vulcanization molding of the green tire to generate closed cells, thereby forming a foamed rubber layer in which short fibrous substances are dispersed in a non-oriented manner. Here, short fibers are generally used as the short fibrous substance, but rod-shaped or needle-shaped organic or inorganic substances may also be used. For example, organic materials such as cut organic fibers such as aromatic polyamide (aramid), vinylon, polyester, nylon, and rayon, needle-like crystals of syndiotactic-1,2-polybutadiene, and whiskers of polyoxymethylene, Examples include whiskers of inorganic materials such as silicon carbide, tungsten carbide, and alumina, and cut inorganic fibers of glass, carbon, graphite, metal, etc., but are not limited to these. Next, blowing agents include, for example, ammonium bicarbonate, sodium bicarbonate, which generate carbon dioxide, and nitrososulfonylazo compounds, which generate nitrogen, such as dinitrosopentamethylenetetramine, N,N'-dimethyl-N, N'-dinitrosophthalamide, azodicarbonamide, N,
N'-dinitrosopentamethylenetetramine, benzenesulfonyl hydrazide, toluenesulfonyl hydrazide, P,P'-oxy-bis(benzenesulfonylhydrazide), P-toluenesulfonyl semicarbazide, P,P'-oxy-bis(benzenesulfonyl semicarbazide) etc. are mentioned,
These are appropriately selected and used depending on the vulcanization temperature. Moreover, urea etc. are mentioned as a foaming aid. In the rubber compounding of the foamed rubber layer of the present invention, in addition to the above-mentioned essential compounding components, carbon black for rubber reinforcement, fillers such as silica, calcium carbonate, clay, etc. may be appropriately selected and used. I can do it. Other compounding agents include softeners, vulcanizing agents, vulcanization accelerators, vulcanization aids, anti-aging agents, optionally colorants, antistatic agents, or to increase the adhesion between short fibrous substances and rubber. For example, an adhesive component such as a methylene acceptor such as resorcinol and a methylene donor such as hexamethylenetetramine or hexamethylmethoxymethylolmelamine is appropriately added in a conventional manner. When a rubber composition containing the above-mentioned short fibrous substances and a blowing agent, and appropriately blended with ordinary rubber compounding agents such as a reinforcing agent such as carbon black and a vulcanization accelerator, is vulcanized under pressure. The vulcanization of the rubber progresses while the foaming agent is dispersed by heat and closed cells are generated in the rubber. This generation of closed cells causes the short fibrous material blended and dispersed in the rubber composition to be displaced, its orientation to be disturbed, and to be dispersed in a non-oriented manner. Next, when the rubber vulcanization molding is completed, the foamed rubber is released from the molding pressure, so the closed cells expand and become larger due to their internal pressure, further displacement of the short fibrous material occurs, and the short fibrous material Non-orientation is further promoted. In addition, when the closed cells in the rubber become larger after vulcanization molding, the rubber is distorted, and the short fibrous material is subjected to tension in the direction of the distortion of the rubber. The elastic modulus of the foamed rubber layer reinforced with fibrous material is further increased. As mentioned above, the tread portion, which has a foamed rubber layer in which short fibrous substances are dispersed in a non-oriented manner, has a higher modulus of elasticity than one simply made of foamed rubber, which improves the handling performance of a pneumatic tire, especially cornering power. It is advantageous for increasing wear resistance, and it is also possible to prevent the above-mentioned abnormal wear caused by anisotropy, which is very advantageous for improving wear resistance. The surface of the treaded rubber becomes a rubber surface with fine irregularities due to the short fibrous substances dispersed in a non-oriented manner and the dispersed closed cells.
The coefficient of friction on wet roads and ice becomes higher, and the grip performance of the tire is significantly improved. In particular, the many recesses formed in the tread by the closed cells, combined with the fine irregularities caused by the blended short fibrous substances, create a barrier between the tire and the road surface, which is a major cause of tire slippage on icy and snowy roads. Since the water film is eliminated, a stronger grip is obtained, and the recesses also provide an edge effect, which greatly improves traction and braking performance. Therefore, the braking performance, etc., is greatly improved, especially when the surface of the ice burn is covered with a thin film of water, so-called wet-on-ice. Even when the tire wears out, these non-oriented short fibrous substances and dispersed closed cells continue to appear on the tread surface that comes into contact with the road surface, ensuring that the above performance is maintained. Become. By the way, the short fibrous substance mixed into the rubber composition preferably has an average length of 5 to 5000 μm, and
It is preferable to have an average length of 10 to 1000 times the average diameter for effective non-orientation of the short fibrous material caused by foaming. In addition, the average cell diameter of the closed cells in the foam rubber layer is
The thickness is desirably 10 to 300 μm, preferably 30 to 150 μm. The cell diameter of the foamed rubber layer was set to 10 to 300 μm, because if it is less than 10 μm, the effect of non-orientation of the short fibrous material cannot be sufficiently obtained, and if it exceeds 300 μm, the abrasion resistance will decrease. This is because the strain recovery power of the foamed rubber layer decreases, so-called so-called set resistance deteriorates, and even during manufacturing, it becomes difficult to obtain a stable shape due to the decrease in permanent set property. In addition, the foaming rate is expressed by the following formula: Vs = {(p 0 - p 9 )/(p 1 - p 9 ) - 1} x 100%...(1), where p 1 is the density of the foam rubber layer (g/ cm 3 ), p 0 is the density of the solid phase part of the foamed rubber layer (g/cm 3 ), p 0
is the gas density (g/cm 3 ) of the foam rubber layer. The foamed rubber layer is composed of a rubber solid phase portion and a cavity (closed cell) formed by the rubber solid phase portion, that is, a gas portion within the cell. The density p 0 of the gas part is extremely small, close to zero, and is extremely small compared to the density p 1 of the rubber solid phase part, so equation (1) is expressed as the following equation: Vs = (p 0 /p 1 -1) ×100%…Almost equivalent to (2). Here, the foaming rate Vs is preferably in the range of 5 to 50%,
Preferably 5-30%, more preferably 10-30%
It is 30%. The foaming rate Vs is set to 5% or more because
This is because if it is less than 5%, the effect of improving ice and snow performance is relatively small. Moreover, if it exceeds 50%, although the improvement in performance on ice is small, it becomes disadvantageous in terms of wear resistance performance on dry road surfaces other than icy and snowy roads and wet roads. In addition, the foamed rubber layer in which the short fibrous material is dispersed in a non-oriented manner accounts for at least 10% of the total volume of the tread portion.
Desirably present, preferably 10-70%,
More preferably, it is 40 to 60%. The reason why the foamed rubber layer is at least 10% of the total volume of the tread portion is that if it is less than 10%, the effect of improving ice and snow performance is small. Furthermore, if it is desired to maintain ice and snow performance over a long period of time, it is of course preferable that the entire tread portion be constructed of such foamed rubber. (Examples) The present invention will be described below based on Examples. Tables 1 and 2 show the blending ratio of the rubber composition (unit: parts by weight), the properties of the rubber composition, and the foamed rubber layer having non-oriented short fibrous material and dispersed closed cells of the present invention. The performance of pneumatic tires with this applied to the tread section is shown. The rubber composition contains natural rubber, polybutadiene rubber, etc. as a rubber component, appropriately uses dinitrone pentamethylene tetramine, azodicarbonamide, and urea (a foaming aid) as a blowing agent, and as a short fibrous material, Examples In Examples 1 to 5, aramid staple fibers (average length 5 μm, average diameter 0.2 μm) were used; in Example 6, nylon staple fibers (average length 0.2 μm) were used.
10 μm, average diameter 0.4 μm) were appropriately mixed and dispersed. Specifically, the rubber compositions of Examples 1 to 5 are formulations that satisfy the preferable ranges specified in the present invention, and Comparative Examples 1 and 2 are examples that do not contain closed cells or short aramid fibers. Also, comparative example 3
and 4 are examples that have closed cells but do not contain aramid short fibers, and Comparative Example 5 is an example that contains aramid short fibers but does not have closed cells. I went. In addition, in Example 6, the foamed rubber composition according to the present invention was used in the tread part of a pneumatic tire to improve braking performance on a wet concrete road surface. It was produced in the same manner as in Example 6 using the composition except for short fibers. Each test method is as follows. (1) Average cell diameter and foaming ratio Vs The average cell diameter is determined by cutting out a block-shaped sample from the tread rubber (foamed rubber) of the test tire, taking a photograph of the cross section of the sample with an optical microscope at a magnification of 100 to 400 times, and measuring 200 cells. Measure the bubble diameter of closed cells of
Expressed as arithmetic mean value. The foaming rate Vs is determined by measuring the density p 1 (g/cm 3 ) of the block-shaped sample, and on the other hand, measuring the density p 0 of the tread portion of the non-foamed rubber (solid phase rubber).
It was calculated using (2). (2) Hardness and tensile stress at 50% elongation A block-shaped sample was cut from the tread rubber of the test tire, and the hardness was measured using a JIS hardness meter in accordance with JIS K6301. In addition, the tensile stress at 50% elongation was measured using a universal tensile tester in accordance with JIS K6301. (3) Abrasion resistance performance Tested using a Pico abrasion tester in accordance with ASTM D2228 and expressed as an index. The larger the number, the better. (4) Coefficient of friction on ice The coefficient of friction on ice of treaded rubber, especially the coefficient of friction on ice in a wet state around 0°C, is calculated by measuring the surface of a sample cut from a foamed rubber layer on ice with a surface temperature of -0.5°C (sample dimensions: length 10mm, width 10mm, thickness 5
mm) and measured using a dynamic/static friction coefficient meter manufactured by Kyowa Interface Science Co., Ltd. Load 2 as measurement condition
Kg/ cm3 , sliding speed 10mm/sec, zero ambient temperature -2℃,
The ice surface was almost mirror-like. (5) Steering stability performance and ride comfort performance The tires of each example or comparative example were
It was attached to a 1500c.c. passenger car and ran at a specified speed on the concrete road surface of a test course, and a feeling test was conducted and the average was calculated. The evaluation was performed using a 10-point evaluation method, with the tire of Comparative Example 1 being used as a control (standard). A + (plus) mark indicates good quality, and a - (minus) mark indicates poor quality. (6) Braking performance on ice Four test tires of each type were mounted on a passenger car with a displacement of 1500 c.c., and the braking distance on ice was measured at an outside temperature of -5°C and a speed of 20 km/h. The index was expressed as 100 for the non-foamed tire (Comparative Example 1). The smaller the value, the better the braking performance. The specific structure of the above pneumatic tire is as follows. That is, as shown in FIG.
The tire has a case 2 and a tread portion 3 having a foamed rubber layer 15 having a non-oriented short fibrous material and dispersed closed cells, which covers the crown portion 2a of the case 2. Case 2
A carcass part 6 consisting of a pair of bead parts 5, a rubberized cord arranged approximately radially between the bead parts 5, a belt part 7 and a carcass part arranged circumferentially on the crown part 2a of the carcass part 6. The sidewall rubber 8 covers the sides of the section 6. Note that 9 is a stiffener rubber, and 3a represents the surface of the tread portion. Further, the structure other than the tread portion 3 is the same as a normal pneumatic tire. The manufacturing method for this pneumatic tire is the same as that for regular tires, and during manufacturing, as mentioned above, the unvulcanized rubber composition is pressurized under heat, and the foaming agent decomposes during vulcanization. This creates closed cells in the rubber, making the short fibrous material non-oriented, and furthermore, by reducing the pressure after vulcanization, the non-orientation of the short fibrous material is further promoted, and the short fibrous material becomes non-oriented in the rubber. The elastic modulus of the foamed rubber layer is further increased by receiving tension in the direction of distortion. A cross section of a tread portion 3 made of a foamed rubber layer 15 in which a short fibrous material is dispersed in a non-oriented manner is shown in FIG. As shown in FIG. 2, a short fibrous material 12 is contained in a foamed rubber layer having dispersed closed cells 11 (indicated by circles in the figure).
are dispersed without orientation.
【表】【table】
【表】
次に、前記表１に基づいて本発明の発泡ゴム組
成物を、第１図に示す空気入りタイヤ（タイヤサ
イズ：165 SR13）１のトレツド部３に用いた実
施例１〜５及び比較例１〜５を比較検討する。
先ず、総論的にみてみると、本発明の実施例１
〜５のものは、比較例１〜５に比べ、乗心地性能
を損なうことなく、特に寒冷地で使用される空気
入りタイヤに要求される氷上制動性能或いは氷上
摩擦係数が非常に優れているとともに操縦安定性
能も優れている。
個別的にみてみると、実施例１のものは、タイ
ヤの氷上制動性能と操縦安定性能がより高度に両
立している。
また、実施例２及び３のものは、特に氷上制動
性能に優れ、操縦安定性能及び乗心地性能も比較
的のものと比べ同等以上で実用上十分なレベルに
ある。
更に、実施例４のものは、操縦安定性能及び氷
上制動性能が優れているとともに、乗心地性能が
著しく向上している。
それに対し、トレツド部に短繊維を含まず、か
つ無発泡である比較例１のものは、実施例１〜４
のものに比べ氷上制動性能が非常に悪く氷雪路面
での使用に不向きであり、また同じく短繊維を含
まず、かつ無発泡である比較例２は、操縦安定性
能が非常に悪い。
独立気泡を有するが短繊維を含まない比較例３
は、実施例１〜４のものに比べ操縦安定性能が非
常に悪い。
更に、短繊維を含むが独立気泡を有しない比較
例５のものは、氷上制動性能が非常に悪く氷雪面
での使用に全く不向きであり、また短繊維の配向
による異方性が出るため配向方向とその直角方向
における50％伸張時の引張応力が著しく異なつて
おり、空気入りタイヤの特異なコーナリング挙動
や異常摩耗を惹起することになる。
なお、空気入りタイヤをより長期間にわたつて
使用するために、本発明のトレツド部の構成を更
生タイヤに適用することも有効である。
また、表２に示されている実施例６は、比較例
６に比較して湿潤コンクリート路面上の摩擦係数
（指数）が大幅に向上しており、制動性能が非常
に改善されている。なお、表２における湿潤コン
クリート路面上の摩擦係数（指数）は、排気量
1500c.c.の乗用車に装着し、テストコースのコンク
リート路面に散水し時速50Km／hrで制動距離を測
定し、比較例６を100として指数化したもので、
値が小さい程、制動性能が良いことを示す。
（発明の効果）
以上説明したように、本発明によれば、無配向
に分散された短繊維状物質と分散された独立気泡
を有する発泡ゴム層を空気入りタイヤのトレツド
部に適用したことにより、耐摩耗性能や操縦安定
性能並びに乗心地性能については従来のタイヤの
一般水準を十分に維持したまま、湿潤路面に対し
て、特に低温時において高い摩擦抵抗をもたらし
氷上制動性能が非常に優れた、特に寒冷地での使
用に適した空気入りタイヤを具現化することが可
能となつた。
しかも、独立気泡の生成により短繊維状物質の
無配向化を行うようにしたものであるので、複数
のゴムシートを短繊維の配向が種々の方向に向く
ように積層する必要がなく、従つて、成型加工時
の工程数が大幅に減少され空気入りタイヤの生産
性が著しく向上する。[Table] Next, based on the above Table 1, Examples 1 to 5 and Comparative Examples 1 to 5 will be compared and studied. First, looking at the general idea, Example 1 of the present invention
Comparative examples 1 to 5 have excellent braking performance on ice or coefficient of friction on ice, which is required for pneumatic tires used in particularly cold regions, without impairing ride quality. It also has excellent handling stability. Looking at the tires individually, the tire of Example 1 has a higher degree of compatibility between the ice braking performance and the steering stability performance of the tire. In addition, Examples 2 and 3 are particularly excellent in braking performance on ice, and the steering stability performance and riding comfort performance are also at a practically sufficient level as compared to the comparative ones, as they are equivalent or better. Furthermore, the vehicle of Example 4 has excellent steering stability performance and braking performance on ice, and has significantly improved ride comfort performance. On the other hand, in Comparative Example 1, which did not contain short fibers in the tread portion and was non-foamed, Examples 1 to 4
Comparative Example 2, which does not contain short fibers and is non-foamed, has very poor braking performance on ice and is unsuitable for use on icy and snowy roads. Comparative Example 3 with closed cells but no short fibers
The steering stability performance is very poor compared to those of Examples 1 to 4. Furthermore, Comparative Example 5, which contains short fibers but does not have closed cells, has very poor braking performance on ice and is completely unsuitable for use on ice and snow surfaces, and also has anisotropy due to the orientation of short fibers. The tensile stress at 50% elongation in the direction and in the direction perpendicular to that direction is significantly different, which causes peculiar cornering behavior and abnormal wear of pneumatic tires. In addition, in order to use the pneumatic tire for a longer period of time, it is also effective to apply the structure of the tread portion of the present invention to a retreaded tire. Further, in Example 6 shown in Table 2, the coefficient of friction (index) on a wet concrete road surface is significantly improved compared to Comparative Example 6, and the braking performance is greatly improved. In addition, the coefficient of friction (index) on the wet concrete road surface in Table 2 is based on the displacement
It was attached to a 1500c.c. passenger car, water was sprinkled on the concrete road surface of the test course, and the braking distance was measured at a speed of 50km/hr. Comparative example 6 was set as 100 and the braking distance was calculated as an index.
The smaller the value, the better the braking performance. (Effects of the Invention) As explained above, according to the present invention, a foamed rubber layer having non-oriented dispersed short fibrous substances and dispersed closed cells is applied to the tread portion of a pneumatic tire. While maintaining the general standards of conventional tires in terms of abrasion resistance, handling stability, and ride comfort, it has high frictional resistance on wet road surfaces, especially at low temperatures, and extremely excellent braking performance on ice. It has now become possible to realize a pneumatic tire that is particularly suitable for use in cold regions. Furthermore, since the short fibrous material is made non-oriented by generating closed cells, there is no need to laminate multiple rubber sheets so that the short fibers are oriented in various directions. , the number of steps during the molding process is significantly reduced, and the productivity of pneumatic tires is significantly improved.
第１図は本発明に係る実施例の空気入りタイヤ
の断面図である。第２図は短繊維状物質が無配向
に分散された発泡ゴム層の断面模式図である。第
３図は従来の成型品の要部概念図である。
１…空気入りタイヤ、２…ケース、３…トレツ
ド部、５…ビード部、６…カーカス部、７…ベル
ト部、８…サイドウオールゴム、１１…独立気
泡、１２…短繊維状物質、１５…発泡ゴム層。
FIG. 1 is a sectional view of a pneumatic tire according to an embodiment of the present invention. FIG. 2 is a schematic cross-sectional view of a foamed rubber layer in which short fibrous substances are dispersed in a non-oriented manner. FIG. 3 is a conceptual diagram of the main parts of a conventional molded product. DESCRIPTION OF SYMBOLS 1... Pneumatic tire, 2... Case, 3... Tread part, 5... Bead part, 6... Carcass part, 7... Belt part, 8... Sidewall rubber, 11... Closed cell, 12... Short fibrous material, 15... Foam rubber layer.
Claims (1)
覆するトレツド部とを備えた寒冷地用空気入りタ
イヤにおいて、平均長さが５〜5000μmで該平均
長さが平均直径の10〜1000倍である無配向に、か
つ、分散して配置された短繊維状物質及び平均気
泡径が10〜300μmの分散して配置された独立気泡
を有する発泡ゴム層が少なくともトレツド部の路
面と接する面に配設されていることを特徴とする
寒冷地用空気入りタイヤ。1. A pneumatic tire for cold regions comprising a tire case and a tread portion covering the crown of the case, with an average length of 5 to 5000 μm and the average length being 10 to 1000 times the average diameter. A foamed rubber layer having oriented and dispersed short fibrous substances and dispersed closed cells with an average cell diameter of 10 to 300 μm is disposed at least on the surface of the tread portion that contacts the road surface. A pneumatic tire for cold regions.
Priority Applications (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP61235923A JPS6389547A (en) | 1986-10-02 | 1986-10-02 | Expanded rubber composition |
| DE19873703480 DE3703480A1 (en) | 1986-02-05 | 1987-02-05 | TIRE |
| US07/527,706 US5147477A (en) | 1986-02-05 | 1990-05-24 | Pneumatic tire having foamed tread rubber |
| US07/944,426 US5351734A (en) | 1986-02-05 | 1992-09-14 | Pneumatic tire with foam rubber in the tread |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP61235923A JPS6389547A (en) | 1986-10-02 | 1986-10-02 | Expanded rubber composition |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS6389547A JPS6389547A (en) | 1988-04-20 |
| JPH0544361B2 true JPH0544361B2 (en) | 1993-07-06 |
Family
ID=16993242
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP61235923A Granted JPS6389547A (en) | 1986-02-05 | 1986-10-02 | Expanded rubber composition |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS6389547A (en) |
Families Citing this family (17)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5176765A (en) * | 1988-04-13 | 1993-01-05 | Bridgestone Corporation | Pneumatic tire having outer tread layer of foam rubber |
| EP0373094A3 (en) * | 1988-12-08 | 1991-04-17 | The Goodyear Tire & Rubber Company | Tire tread containing fibrillated fibers |
| JP2901257B2 (en) * | 1988-12-08 | 1999-06-07 | 株式会社ブリヂストン | Heavy duty pneumatic tires |
| JPH03252432A (en) * | 1990-03-01 | 1991-11-11 | Bridgestone Corp | Rubber composition |
| JP2782551B2 (en) * | 1990-05-31 | 1998-08-06 | 横浜ゴム株式会社 | Pneumatic tire |
| US5753365A (en) * | 1991-06-07 | 1998-05-19 | Bridgestone Corporation | Rubber composition and all season type pneumatic tires made from a rubber composition |
| US5679744A (en) * | 1994-11-11 | 1997-10-21 | The Yokohama Rubber Co., Ltd. | Rubber composition |
| EP0719658B1 (en) * | 1994-12-27 | 2000-03-29 | Bridgestone Corporation | Foamed rubber composition for tires and pneumatic tire using the same |
| US5776991A (en) * | 1995-03-29 | 1998-07-07 | Bridgestone Corporation | Foamed rubber compositions for pneumatic tires and method of producing the same |
| JPH08291226A (en) * | 1995-04-20 | 1996-11-05 | Nippon Kemifueruto Kk | Production of non-slip sheet made of polymer |
| US5975173A (en) * | 1995-11-06 | 1999-11-02 | Bridgestone Corporation | Pneumatic tire using fiber composite material |
| KR100291495B1 (en) * | 1998-04-07 | 2001-06-01 | 신형인 | Method for manufacturing radial-ply tire improved in joining method of side wheel |
| JP4632756B2 (en) * | 2004-11-16 | 2011-02-16 | 株式会社ブリヂストン | Pneumatic tire manufacturing method |
| JP4868578B2 (en) * | 2006-04-13 | 2012-02-01 | 東洋ゴム工業株式会社 | Pneumatic tire |
| JP5870507B2 (en) * | 2011-05-13 | 2016-03-01 | 横浜ゴム株式会社 | Expandable rubber composition |
| US10694813B2 (en) | 2013-05-01 | 2020-06-30 | Asics Corporation | Shoe sole member |
| JP6127015B2 (en) * | 2014-04-28 | 2017-05-10 | 貞晋 大工 | Foam rubber pig and manufacturing method thereof |
Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS56154304A (en) * | 1980-04-24 | 1981-11-28 | Toyo Rubber Chem Ind Co Ltd | Foamed tire |
| JPS5824122A (en) * | 1981-07-06 | 1983-02-14 | アメテク・エアロスペース・プロダクツ・インコーポレイテッド | Display unit |
| JPS591550A (en) * | 1982-06-29 | 1984-01-06 | Bridgestone Corp | Rubber composition having improved crack propagation resistance |
| JPS6044538A (en) * | 1983-08-19 | 1985-03-09 | Yokohama Rubber Co Ltd:The | Rubber composition for tire tread |
| JPS6094805A (en) * | 1983-10-31 | 1985-05-28 | Yokohama Rubber Co Ltd:The | Pneumatic tire |
-
1986
- 1986-10-02 JP JP61235923A patent/JPS6389547A/en active Granted
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS56154304A (en) * | 1980-04-24 | 1981-11-28 | Toyo Rubber Chem Ind Co Ltd | Foamed tire |
| JPS5824122A (en) * | 1981-07-06 | 1983-02-14 | アメテク・エアロスペース・プロダクツ・インコーポレイテッド | Display unit |
| JPS591550A (en) * | 1982-06-29 | 1984-01-06 | Bridgestone Corp | Rubber composition having improved crack propagation resistance |
| JPS6044538A (en) * | 1983-08-19 | 1985-03-09 | Yokohama Rubber Co Ltd:The | Rubber composition for tire tread |
| JPS6094805A (en) * | 1983-10-31 | 1985-05-28 | Yokohama Rubber Co Ltd:The | Pneumatic tire |
Also Published As
| Publication number | Publication date |
|---|---|
| JPS6389547A (en) | 1988-04-20 |
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