JPH0355497B2 - - Google Patents

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Publication number
JPH0355497B2
JPH0355497B2 JP15168086A JP15168086A JPH0355497B2 JP H0355497 B2 JPH0355497 B2 JP H0355497B2 JP 15168086 A JP15168086 A JP 15168086A JP 15168086 A JP15168086 A JP 15168086A JP H0355497 B2 JPH0355497 B2 JP H0355497B2
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JP
Japan
Prior art keywords
fibers
flame
sulfur
fiber
friction material
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
Application number
JP15168086A
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Japanese (ja)
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JPS638424A (en
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Priority to JP15168086A priority Critical patent/JPS638424A/en
Priority to PCT/JP1987/000219 priority patent/WO1987006276A1/en
Priority to DE19873783423 priority patent/DE3783423T2/en
Priority to EP87902710A priority patent/EP0263884B1/en
Publication of JPS638424A publication Critical patent/JPS638424A/en
Priority to US07/412,563 priority patent/US5502090A/en
Publication of JPH0355497B2 publication Critical patent/JPH0355497B2/ja
Granted legal-status Critical Current

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    • DTEXTILES; PAPER
    • D06TREATMENT OF TEXTILES OR THE LIKE; LAUNDERING; FLEXIBLE MATERIALS NOT OTHERWISE PROVIDED FOR
    • D06MTREATMENT, NOT PROVIDED FOR ELSEWHERE IN CLASS D06, OF FIBRES, THREADS, YARNS, FABRICS, FEATHERS OR FIBROUS GOODS MADE FROM SUCH MATERIALS
    • D06M11/00Treating fibres, threads, yarns, fabrics or fibrous goods made from such materials, with inorganic substances or complexes thereof; Such treatment combined with mechanical treatment, e.g. mercerising
    • D06M11/51Treating fibres, threads, yarns, fabrics or fibrous goods made from such materials, with inorganic substances or complexes thereof; Such treatment combined with mechanical treatment, e.g. mercerising with sulfur, selenium, tellurium, polonium or compounds thereof
    • D06M11/55Treating fibres, threads, yarns, fabrics or fibrous goods made from such materials, with inorganic substances or complexes thereof; Such treatment combined with mechanical treatment, e.g. mercerising with sulfur, selenium, tellurium, polonium or compounds thereof with sulfur trioxide; with sulfuric acid or thiosulfuric acid or their salts
    • D06M11/57Sulfates or thiosulfates of elements of Groups 3 or 13 of the Periodic Table, e.g. alums
    • CCHEMISTRY; METALLURGY
    • C04CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04BLIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B16/00Use of organic materials as fillers, e.g. pigments, for mortars, concrete or artificial stone; Treatment of organic materials specially adapted to enhance their filling properties in mortars, concrete or artificial stone
    • C04B16/04Macromolecular compounds
    • C04B16/06Macromolecular compounds fibrous
    • DTEXTILES; PAPER
    • D01NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
    • D01FCHEMICAL FEATURES IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS; APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OF CARBON FILAMENTS
    • D01F6/00Monocomponent artificial filaments or the like of synthetic polymers; Manufacture thereof
    • D01F6/02Monocomponent artificial filaments or the like of synthetic polymers; Manufacture thereof from homopolymers obtained by reactions only involving carbon-to-carbon unsaturated bonds
    • D01F6/18Monocomponent artificial filaments or the like of synthetic polymers; Manufacture thereof from homopolymers obtained by reactions only involving carbon-to-carbon unsaturated bonds from polymers of unsaturated nitriles, e.g. polyacrylonitrile, polyvinylidene cyanide

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Textile Engineering (AREA)
  • Ceramic Engineering (AREA)
  • Organic Chemistry (AREA)
  • Structural Engineering (AREA)
  • Materials Engineering (AREA)
  • Health & Medical Sciences (AREA)
  • Toxicology (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • General Chemical & Material Sciences (AREA)
  • Braking Arrangements (AREA)
  • Manufacture Of Macromolecular Shaped Articles (AREA)

Description

【発明の詳細な説明】[Detailed description of the invention]

(産業上の利用分野) 本発明は、摩擦材、たとえば車両等のブレーキ
に使用される摩擦材に係り、さらに詳しくは高強
度で、耐摩耗性および耐熱性に優れたアクリル系
耐炎化繊維を基材とする摩擦材に関する。 (従来の技術) 従来、摩擦材には石綿を基材とし、この石綿に
結合剤と滑材などの摩擦特性を向上させる各種材
料を配合し、所定の形状に賦型したものが使用さ
れてきた。 しかしながら、この石綿を基材とする摩擦材
は、配合組成物の分散混合工程や仕上げ工程など
で粉塵化し、多量の石綿を含有する粉塵が工場内
に飛散するために、製造に従事する従業者の健康
を著しく害するという環境衛生上の大きな問題が
あつた。特にこの石綿がモルモツトの動物実験に
よつて肺癌を誘発することが実証された現在、欧
米諸国においては法的にその使用が制限されるに
至り、国内においても石綿の使用は従業者が強く
忌避するところとなつてきた。 そこでこの石綿に代替する材料として、各種の
繊維、たとえば炭素繊維、スチール繊維、ガラス
繊維、アラミド繊維(“ケプラー”)、フエノール
繊維および耐炎化繊維などが提案され、これらの
代替繊維の中で比重が小さく、柔軟で、難燃性に
優れ、かつ炭素繊維に比較して製造コストが安価
なアクリル系繊維をプレカーサとして得られるア
クリル系耐炎化繊維が注目されている。そして、
特公昭59−4456号公報には、アクリル系繊維を空
気中で酸化して得られる耐炎化繊維を基材とした
ブレーキライニングが提案されている。 しかし、アクリル系繊維を高温の空気中で加
熱、酸化することによつて製造される耐炎化繊維
は、繊維内部に比較して繊維の表皮部の酸化の程
度が極めて大きい不均一な酸化構造を有している
ために、機械的強度、特に引張強度が小さく、靭
性(タフネス)が低く、耐摩耗性および耐熱性が
悪く、たとえば150℃以上の高温下で長時間使用
すると、その強度を失い、摩擦材などに使用した
場合に耐久性が十分ではないという実用性能上の
問題があつた。 特公昭47−36461号公報によると、アクリル系
繊維をプレカーサとして二酸化硫黄含有雰囲気中
で加熱することによつてプレカーサよりも強力の
大きい硫黄含有炎化繊維が得られることが記載さ
れている。本発明者らはこの硫黄含有雰囲気中で
のアクリル系繊維の耐炎化によつて得られる耐炎
化繊維の特性および摩擦材への適用について鋭
意、検討を進めて本発明を為すに至つたものであ
る。 (発明の解決ようとする問題点) 本発明の目的は、高温における耐摩耗性および
耐熱性に優れ、ヒビ割れを生じ難い新規摩擦材を
提供するにあり、他の目的は前記環境衛生上大き
な問題のある石綿に代替し得る摩擦材を提供する
にある。 (問題点を解決するための手段) このような本発明の目的は、前記特許請求の範
囲に記載したように、 硫黄含有量が少なくとも3重量%である硫黄含
有アクリル系耐炎化繊維を基材とする摩擦材 によつて達成することができる。 本発明において、硫黄含有アクリル系耐炎化繊
維は従来の炭素繊維製造の中間体として得られる
空気等の酸化性雰囲気中で加熱することによつて
得られる酸化繊維とは異なり、硫黄含有雰囲気中
で加熱することによつて得られる硫黄含有環化構
造および硫黄架橋結合などを有し、このような構
造および結合の導入によつて耐炎性や機械的強度
のみならず、耐熱性並びに靭性(タフネス)を顕
著に改良、向上せしめた耐炎化繊維である。 本発明の摩擦材を構成する硫黄含有耐炎化繊維
は、該繊維中に含有される硫黄量が少なくとも3
重量%(以下、特に断らないときは%は重量%を
示す)、好ましくは5%以上であることが望まし
い。すなわち硫黄含有量が3%未満の場合は繊維
としての耐熱性が低下するほか、摩擦材としての
耐久性および耐摩耗性の大巾な向上を期待できな
いので好ましくない。 本発明に用いる硫黄含有量が少なくとも3%で
ある硫黄含有アクリル系耐炎化繊維は、以下に詳
述するように、アクリル系繊維をプレカーサとし
て使用し、特定の耐炎化工程および条件を採用す
ることによつてはじめて製造することができる繊
維である。 そして、このアクリル系繊維は、硫黄含有雰囲
気中で比較的緩慢な反応条件下に加熱、硫化せし
め、繊維内部まで十分に硫黄結合が導入された内
外構造差の少ない耐炎化繊維にすることが重要で
あるが、このような内外構造差の少ない、高強度
の硫黄含有耐炎化繊維を製造するためには、プレ
カーサのアクリル系繊維としても内外構造差の少
ない、緻密で高強度のアクリル系繊維であること
が望ましい。 本発明の硫黄含有アクリル系耐炎化繊維の製造
に使用されるプレカーサ、すなわちアクリル系繊
維としては、アクリロニトリル(以下、ANとい
う)AN単独または少なくとも95モル%のANと
5モル%以下の該ANに対して共重合性を有する
モノマ、たとえばアクリル酸、メタクリル酸、イ
タコン酸などのカルボン酸およびそれらの低級ア
ルキルエステル類、ヒドロキシメチルアクリレー
ト、ヒドロキシエチルアクリレート、ヒドロキシ
メチルメタクリレートなどのカルボン酸の水酸基
を含有するヒドロキシアルキルアクリレート、ア
クリルアミド、メタクリルアミド、α−クロルア
クリロニトリル、ヒドロキシエチルアクリル酸、
アリルスルホン酸、メタクリルスルホン酸などと
の共重合体からなる繊維を例示することができ
る。好ましくは、その極限粘度が少なくとも1.5、
さらに好ましくは2.0〜5.0の高重合度AN系ポリ
マがよい。 これらのAN系ポリマは、ジメチルスルホキシ
ド(DMSO)、ジメチルアセタミド(DMAc)、
ジメチルホルムアミド(DMF)などの有機溶剤、
塩化カルシウム、塩化亜鉛、ロダンソーダなどの
無機塩濃厚水溶液、硝酸などの無機系溶剤に溶解
して、ポリマ濃度が5〜20%の紡糸原液とし、湿
式、乾式または乾・湿式紡糸法、好ましくは乾・
湿式紡糸法によつて繊度が0.5〜7デニール(d)、
好ましくは1〜5dの繊維を作成する。 この繊度が0.5dよりも小さいと、得られる耐炎
化繊維の強力が小さく、耐摩耗性の良好な摩擦材
を得ることが困難になるし、7dよりも大きいと、
繊維断面において硫化が均一な酸化処理を行うこ
とが難しくなるので好ましくない。 特に極限粘度が2.5以上の高重合度AN系ポリマ
の溶剤溶液(紡糸原液)を用いて、乾・湿式紡糸
法、たとえば紡糸口金面と凝固浴液面との間の距
離が1〜20mm、好ましくは3〜10mmの範囲内に設
定された該紡糸口金孔を通して、前記紡糸原液を
凝固浴に導き、得られた凝固繊維糸条を常法によ
り、水洗、脱溶媒、1次延伸、乾燥・緻密化し、
得られた極めて延伸性に優れている繊維糸条を
150〜270℃の乾熱下に1.1倍、好ましくは1.5倍以
上延伸し、全有効延伸倍率が少なくとも10倍、好
ましくは12倍以上であり、引張強度が少なくとも
10g/d以上の高強度、高弾性率で、内外構造差
の少ない緻密な繊維を製造するのがよい。 かくして得られたアクリル系繊維プレカーサ
は、硫黄含有雰囲気、たとえば二硫化炭素、硫化
水素、二硫化硫黄および硫黄ガスなどの単独また
は混合ガス中で加熱、硫化されるが、好ましくは
繊維断面全体が均一に硫化された(二重構造でな
い)繊維を再現性よく製造できる二酸化硫黄を硫
黄含有雰囲気として使用するのがよく、また耐炎
化温度は250〜400℃の温度領域で加熱、硫化する
のがよい。 この二酸化硫黄雰囲気中でのアクリル系繊維の
硫化は、空気などの通常の酸化性雰囲気における
酸化に比較して反応が緩慢であり、二酸化硫黄が
繊維中にスムースに浸透し、結果として硫黄原子
が繊維断面全体に均一に分布した、内外構造差の
ない耐炎化繊維を形成するのである。 本発明において、前記硫黄含有雰囲気、特に二
酸化硫黄雰囲気中には、窒素、酸素などの他のガ
スを適宜混合した加熱雰囲気であつてもよく、特
に二酸化硫黄と窒素との混合ガスは、二酸化硫黄
を効率よく繊維と反応させる上で有効である。こ
の耐炎化工程の加熱は、一定温度条件下でもよい
し、昇温下でもよい。たとえば、第1段加熱を
250〜290℃の温度範囲に保たれた加熱炉中で行
い、第2段加熱を290〜400℃の温度範囲内で、か
つ段階的に昇温条件に設定された加熱炉内で加熱
して繊維を硫化し、耐炎化を完結させる方法を例
示することができる。 また、アクリル系繊維プレカーサは、弛緩、緊
張および定長のいずれの条件下に加熱してもよい
が、引張強度の大きい耐炎化繊維を製造する上で
は、できるだけ高張力下、たとえば少なくとも
0.3g/d以上の張力を与えて、加熱して繊維を
硫化し、耐炎化せしめるのがよい。 かくして得られる硫黄含有アクリル系繊維は、
上述したように硫黄原子が導入されれているだけ
ではなくて、該硫黄原子が繊維断面全体に均一に
分布した構造を有しているために、少なくとも3
g/d、好ましくは4g/d以上という高強度お
よび優れた耐熱性を示すので、摩擦材として優れ
た性能、たとえば耐久性、耐摩耗性などを有す
る。 次に上記硫黄含有アクリル系耐炎化繊維(以
下、単に耐炎化繊維という)から本発明の摩擦材
を作成する方法としては、特に限定されるもので
はなく、通常の方法を適用すればよい。たとえ
ば、該耐炎化繊維を長さ1〜10mmにカツトし、マ
トリツクス樹脂およびその他の添加物と共に混合
した後、成形し摩擦材にすることができる。耐炎
化繊維は上記カツト繊維のみならず、フイラメン
トや紡績糸などの長繊維から各種の布帛を作成
し、これらの布帛を摩擦材の基布としてもよい
し、長繊維または短繊維不織布を作成し、この不
織布を摩擦材の基布としてもよい。 マトリツクス樹脂としては、特に限定されるも
のではないが、フエノール樹脂、エポキシ樹脂、
ポリイミド樹脂、芳香族ポリエステル系樹脂、含
硫黄耐熱性樹脂など耐熱性や摩擦特性に優れた樹
脂を使用するのがよい。 添加物としては、耐熱性を有する各種繊維類、
たとえばアラミド繊維、炭素繊維、スチール繊
維、ガラス繊維、フエノール繊維、ポリイミド繊
維およびアスベストを例示することができる。ま
た、摩擦特性の改質を目的に各種無機および有機
充填剤、たとえば黒鉛、シリカ粉、アルミナ粉、
硫酸バリウム、金属粉、マイカ、クレー、炭酸カ
ルシウム、二硫化モリブデン、バライト、カシユ
ダスト、ラバーダストなどを配合することができ
る。 さらに本発明に用いる耐炎化繊維は、硫黄が含
有されていることに基因して、マトリツクス樹脂
に対する接着性に優れているために、摩擦材にお
けるマトリツクス樹脂の配合量を少なくすること
ができる。摩擦材中のマトリツクス樹脂は、繊維
やフイラーの接着剤の役割を有するが、通常マト
リツクス樹脂量が多くなるにつれて摩擦材の耐熱
性が低下し、反対に繊維やフイラーの接合力は増
大する。しかるに本発明に使用する耐炎化繊維
は、マトリツクス樹脂に対する接着性に優れてい
るので、マトリツク樹脂量を少なくし、摩擦材の
耐熱性を大きく向上させることが可能になるので
ある。 (発明の効果) 本発明になる少なくとも3重量%の硫黄を含有
する硫黄含有アクリル系耐炎化繊維は、耐摩耗
性、耐熱性およびマトリツクス樹脂に対する接着
性に極めて優れた繊維であるから、高温、たとえ
ば少なくとも300℃以上の温度領域でも摩擦材と
しての特性を十分に発揮する。したがつて、たと
えば高圧力下に短時間で回転する自動車や各種機
械のブレーキなどの回転体において、回転体の停
止時に回転体は多量の熱を発生し、高度の耐熱性
が要求されることになるが、この高速回転体に要
求される高度の耐熱性を十分に満足する摩擦材を
与えるのである。 このような本発明の摩擦材は上記自動車のデイ
スクパツド、ブレーキライニング材料、クラツチ
などのみならず、一般産業用の摩擦材として極め
て有用である。以下、実施例により本発明の効果
をさらに具体的に説明する。 なお、本発明において、摩擦特性、耐熱性は次
の測定法により測定した値である。 摩擦特性: 耐炎化繊維を基材とする板状の摩擦材を鈴木式
摩耗試験機を用いて、荷重10Kg/cm2、周速度
100m/min、温度250℃、および350℃で摩耗し
た時の摩擦係数と摩耗量を求め、現行素材のアス
ベストの摩耗量を100とし、その相対値を以て表
示した。 耐熱性: 耐炎化繊維を180℃の空気中に弛緩状態で10日
間加熱した後の強力保持率(%)をもつて示し
た。 実施例 1 アクリロニトリル(AN)99.7モル%とイタコ
ン酸0.3モル%からなる極限粘度が3.2のAN系共
重合体をジメチルスルホキシド(DMSO)に溶
解し、得られた紡糸原液を乾・湿式紡糸法によつ
て紡糸し、延伸、熱処理などの後処理を施して、
強度が11.3g/d、伸度13%のアクリル系繊維を
得た。このアクリル系繊維をプレカーサとして
300℃の亜硫酸ガス中で40分間加熱し、第1表に
示した硫黄含有アクリル系耐炎化繊維を得た。 この耐炎化繊維を約1mmにカツトし、該耐炎化
繊維、フエノール系樹脂およびCaCO3フイラー
を容積比率で57:25:18で混合し、この配合物を
金型に入れ、180℃、200Kg/cm2の条件下にホツト
プレスして成形した後、得られた成型品の表面を
研磨し600番のサンドペーパー(水有り状態)で
仕上げて水洗、乾燥して摩擦材を作成した。 この摩擦材の摩擦係数、摩耗量などの摩擦特性
を同じく第1表に示した。 比較例 1〜3 実施例1において、亜硫酸ガス中での加熱条件
(Industrial Application Field) The present invention relates to a friction material, for example, a friction material used in the brakes of vehicles, etc., and more specifically, the present invention relates to a friction material, for example, a friction material used for brakes of vehicles, etc., and more specifically, it is made of flame-resistant acrylic fibers that have high strength, excellent abrasion resistance, and heat resistance. This invention relates to a friction material used as a base material. (Prior art) Conventionally, friction materials have been used that have asbestos as a base material, which is mixed with various materials that improve frictional properties such as a binder and a lubricant, and then shaped into a predetermined shape. Ta. However, this asbestos-based friction material turns into dust during the dispersion mixing process and finishing process of the compounded composition, and a large amount of asbestos-containing dust is scattered within the factory, making it difficult for employees engaged in manufacturing. There was a major environmental health problem that seriously harmed people's health. In particular, now that it has been proven that asbestos can induce lung cancer in animal experiments on guinea pigs, its use has come to be legally restricted in Western countries, and even in Japan, employees strongly discourage the use of asbestos. It has become a place to do it. Therefore, various fibers such as carbon fiber, steel fiber, glass fiber, aramid fiber (Keplar), phenol fiber, and flame-retardant fiber have been proposed as materials to replace asbestos. Acrylic flame-resistant fibers, which are obtained by using acrylic fibers as a precursor, are attracting attention because they are small in size, flexible, have excellent flame retardancy, and are cheaper to manufacture than carbon fibers. and,
Japanese Patent Publication No. 59-4456 proposes a brake lining made of flame-resistant fibers obtained by oxidizing acrylic fibers in the air. However, flame-resistant fibers produced by heating and oxidizing acrylic fibers in high-temperature air have a non-uniform oxidation structure in which the surface area of the fibers is much more oxidized than the inside of the fibers. As a result, mechanical strength, especially tensile strength, is low, toughness is low, and wear resistance and heat resistance are poor. For example, if used for a long time at high temperatures of 150℃ or higher, it will lose its strength. However, when used as a friction material, there was a practical performance problem in that the durability was insufficient. According to Japanese Patent Publication No. 47-36461, it is described that by heating an acrylic fiber as a precursor in an atmosphere containing sulfur dioxide, a sulfur-containing flamed fiber having stronger strength than the precursor can be obtained. The present inventors have diligently studied the characteristics of flame-resistant fibers obtained by flame-proofing acrylic fibers in a sulfur-containing atmosphere and their application to friction materials, and have thus arrived at the present invention. be. (Problems to be Solved by the Invention) An object of the present invention is to provide a new friction material that has excellent wear resistance and heat resistance at high temperatures and is less prone to cracking. The purpose of the present invention is to provide a friction material that can replace the problematic asbestos. (Means for Solving the Problems) The object of the present invention is to provide a base material made of sulfur-containing acrylic flame-resistant fiber having a sulfur content of at least 3% by weight, as described in the claims. This can be achieved by using a friction material. In the present invention, the sulfur-containing acrylic flame-resistant fiber is produced in a sulfur-containing atmosphere, unlike the oxidized fiber obtained by heating in an oxidizing atmosphere such as air, which is obtained as an intermediate in conventional carbon fiber production. It has a sulfur-containing cyclized structure and sulfur crosslinks that can be obtained by heating, and the introduction of such structures and bonds improves not only flame resistance and mechanical strength, but also heat resistance and toughness. It is a flame-resistant fiber with significantly improved and improved properties. The sulfur-containing flame-resistant fibers constituting the friction material of the present invention have a sulfur content of at least 3
It is desirable that the amount is 5% or more by weight (hereinafter, % indicates weight % unless otherwise specified), preferably 5% or more. That is, when the sulfur content is less than 3%, the heat resistance as a fiber decreases, and a significant improvement in durability and abrasion resistance as a friction material cannot be expected, which is not preferable. The sulfur-containing acrylic flame-retardant fibers with a sulfur content of at least 3% used in the present invention can be obtained by using acrylic fibers as precursors and by employing specific flame-retardant processes and conditions, as detailed below. It is a fiber that can only be produced by It is important to heat and sulfurize this acrylic fiber under relatively slow reaction conditions in a sulfur-containing atmosphere to make it a flame-resistant fiber with sufficient sulfur bonds introduced into the interior of the fiber and little difference in structure between the inside and outside. However, in order to manufacture high-strength sulfur-containing flame-resistant fibers with little difference in structure between the inside and outside, it is necessary to use dense, high-strength acrylic fibers with little difference in structure between the inside and outside as precursor acrylic fibers. It is desirable that there be. The precursor, i.e., acrylic fiber, used in the production of the sulfur-containing acrylic flame-resistant fiber of the present invention includes acrylonitrile (hereinafter referred to as AN), AN alone, or at least 95 mol% of AN and 5 mol% or less of the AN. Monomers that are copolymerizable with esters, such as carboxylic acids such as acrylic acid, methacrylic acid, and itaconic acid, and their lower alkyl esters, and hydroxyl groups of carboxylic acids such as hydroxymethyl acrylate, hydroxyethyl acrylate, and hydroxymethyl methacrylate. Hydroxyalkyl acrylate, acrylamide, methacrylamide, α-chloroacrylonitrile, hydroxyethyl acrylic acid,
Examples include fibers made of copolymers with allylsulfonic acid, methacrylsulfonic acid, and the like. Preferably, its intrinsic viscosity is at least 1.5;
More preferably, it is an AN-based polymer with a high degree of polymerization of 2.0 to 5.0. These AN-based polymers include dimethyl sulfoxide (DMSO), dimethyl acetamide (DMAc),
organic solvents such as dimethylformamide (DMF),
A spinning stock solution with a polymer concentration of 5 to 20% is obtained by dissolving in a concentrated aqueous solution of inorganic salts such as calcium chloride, zinc chloride, and rhodan soda, or in an inorganic solvent such as nitric acid, and is then processed by a wet, dry or dry/wet spinning method, preferably a dry spinning method.・
The fineness is 0.5-7 denier (d) by wet spinning method.
Preferably, fibers of 1 to 5 d are made. If the fineness is smaller than 0.5d, the strength of the flame-resistant fibers obtained will be low, making it difficult to obtain a friction material with good wear resistance; if the fineness is larger than 7d,
This is not preferable because it becomes difficult to perform an oxidation treatment with uniform sulfurization on the fiber cross section. In particular, using a solvent solution (spinning stock solution) of a highly polymerized AN-based polymer with an intrinsic viscosity of 2.5 or more, dry/wet spinning methods are used, for example, the distance between the spinneret surface and the coagulation bath liquid level is preferably 1 to 20 mm. The spinning stock solution is introduced into a coagulation bath through the spinneret hole set within the range of 3 to 10 mm, and the obtained coagulated fiber thread is washed with water, desolventized, primary stretched, dried and densified by conventional methods. turned into
The obtained fiber yarn with extremely excellent drawability is
Stretched by 1.1 times, preferably 1.5 times or more under dry heat at 150-270℃, the total effective stretching ratio is at least 10 times, preferably 12 times or more, and the tensile strength is at least
It is preferable to produce dense fibers with a high strength of 10 g/d or more, a high modulus of elasticity, and little difference in structure between the inside and outside. The acrylic fiber precursor thus obtained is heated and sulfurized in a sulfur-containing atmosphere, such as carbon disulfide, hydrogen sulfide, sulfur disulfide, and sulfur gas alone or in a mixture, but preferably the entire fiber cross section is uniform. It is best to use sulfur dioxide as the sulfur-containing atmosphere because it can produce sulfurized (non-double structure) fibers with good reproducibility, and it is best to heat and sulfurize at a flameproof temperature range of 250 to 400℃. . The sulfurization of acrylic fibers in this sulfur dioxide atmosphere is slower than oxidation in normal oxidizing atmospheres such as air, and sulfur dioxide penetrates into the fibers smoothly, resulting in the formation of sulfur atoms. This creates flame-resistant fibers that are uniformly distributed over the entire fiber cross-section and have no difference in internal or external structure. In the present invention, the sulfur-containing atmosphere, particularly the sulfur dioxide atmosphere, may be a heated atmosphere in which other gases such as nitrogen and oxygen are appropriately mixed. In particular, the mixed gas of sulfur dioxide and nitrogen is sulfur dioxide. It is effective in efficiently reacting with fibers. Heating in this flameproofing step may be performed under constant temperature conditions or under elevated temperature conditions. For example, the first stage heating
The second stage heating is carried out in a heating furnace maintained at a temperature range of 250 to 290°C, and the second stage is heated within a temperature range of 290 to 400°C in a heating furnace set to gradual temperature increase conditions. A method of sulfurizing fibers to complete flame resistance can be exemplified. Furthermore, although the acrylic fiber precursor may be heated under any of the following conditions: relaxed, tensioned, and constant length, in order to produce flame-resistant fibers with high tensile strength, it is preferable to heat the acrylic fiber precursor under as high a tension as possible, for example, at least
It is preferable to apply a tension of 0.3 g/d or more and heat to sulfurize the fibers and make them flame resistant. The sulfur-containing acrylic fiber thus obtained is
As mentioned above, not only are sulfur atoms introduced, but also the structure is such that the sulfur atoms are uniformly distributed over the entire cross section of the fiber.
Since it exhibits high strength of g/d, preferably 4 g/d or more, and excellent heat resistance, it has excellent performance as a friction material, such as durability and abrasion resistance. Next, the method for producing the friction material of the present invention from the sulfur-containing acrylic flame-resistant fiber (hereinafter simply referred to as flame-resistant fiber) is not particularly limited, and any conventional method may be used. For example, the flame-resistant fibers can be cut into lengths of 1 to 10 mm, mixed with a matrix resin and other additives, and then molded into a friction material. Flame-resistant fibers include not only the cut fibers mentioned above, but also various fabrics made from long fibers such as filaments and spun yarns, and these fabrics can be used as base fabrics for friction materials, or long fibers or short fibers can be made from nonwoven fabrics. , this nonwoven fabric may be used as a base fabric for a friction material. Examples of matrix resins include, but are not limited to, phenol resins, epoxy resins,
It is preferable to use resins with excellent heat resistance and frictional properties, such as polyimide resins, aromatic polyester resins, and sulfur-containing heat-resistant resins. Additives include various heat-resistant fibers,
Examples include aramid fibers, carbon fibers, steel fibers, glass fibers, phenol fibers, polyimide fibers and asbestos. In addition, various inorganic and organic fillers such as graphite, silica powder, alumina powder,
Barium sulfate, metal powder, mica, clay, calcium carbonate, molybdenum disulfide, barite, oak dust, rubber dust, etc. can be blended. Furthermore, the flame-resistant fiber used in the present invention has excellent adhesion to matrix resin due to the sulfur content, and therefore the amount of matrix resin blended in the friction material can be reduced. The matrix resin in the friction material has the role of an adhesive for the fibers and filler, but as the amount of matrix resin increases, the heat resistance of the friction material usually decreases, and conversely, the bonding strength of the fibers and filler increases. However, since the flame-resistant fiber used in the present invention has excellent adhesion to matrix resin, it is possible to reduce the amount of matrix resin and greatly improve the heat resistance of the friction material. (Effects of the Invention) The sulfur-containing flame-resistant acrylic fiber containing at least 3% by weight of sulfur according to the present invention is a fiber with extremely excellent abrasion resistance, heat resistance, and adhesion to matrix resin. For example, it fully exhibits its characteristics as a friction material even in a temperature range of at least 300°C or higher. Therefore, for example, in rotating bodies such as the brakes of automobiles and various machines that rotate under high pressure for a short time, the rotating body generates a large amount of heat when it stops, and a high degree of heat resistance is required. However, it provides a friction material that fully satisfies the high degree of heat resistance required for this high-speed rotating body. Such a friction material of the present invention is extremely useful not only for disc pads, brake lining materials, clutches, etc. of the above-mentioned automobiles, but also as a friction material for general industrial use. Hereinafter, the effects of the present invention will be explained in more detail with reference to Examples. In the present invention, the frictional properties and heat resistance are values measured by the following measuring method. Friction properties: A plate-shaped friction material based on flame-resistant fiber was tested using a Suzuki abrasion tester at a load of 10 kg/cm 2 and a circumferential speed.
The friction coefficient and amount of wear when worn at 100 m/min and temperatures of 250°C and 350°C were determined, and the wear amount of the current material asbestos was assumed to be 100, and the relative values were displayed. Heat resistance: The strength retention rate (%) is shown after flame-resistant fibers are heated in air at 180°C in a relaxed state for 10 days. Example 1 An AN copolymer with an intrinsic viscosity of 3.2 consisting of 99.7 mol% acrylonitrile (AN) and 0.3 mol% itaconic acid was dissolved in dimethyl sulfoxide (DMSO), and the resulting spinning stock solution was subjected to dry/wet spinning methods. It is twisted, spun, and subjected to post-treatments such as stretching and heat treatment.
Acrylic fibers with a strength of 11.3 g/d and an elongation of 13% were obtained. This acrylic fiber is used as a precursor
The mixture was heated in sulfur dioxide gas at 300°C for 40 minutes to obtain the sulfur-containing acrylic flame-resistant fibers shown in Table 1. This flame resistant fiber was cut into pieces of approximately 1 mm, the flame resistant fiber, phenolic resin and CaCO 3 filler were mixed in a volume ratio of 57:25:18, this mixture was put into a mold, heated at 180°C, 200 kg/ After hot-pressing and molding under cm 2 conditions, the surface of the resulting molded product was polished and finished with No. 600 sandpaper (with water), washed with water, and dried to create a friction material. The friction characteristics of this friction material, such as the friction coefficient and amount of wear, are also shown in Table 1. Comparative Examples 1 to 3 In Example 1, heating conditions in sulfur dioxide gas

【表】 を250℃、30分とした以外同様に加熱焼成して、
第1表に示す繊維特性を有する硫黄含有アクリル
系耐炎化繊維を作成した。 また、同じく実施例1のアクリル系繊維を250
℃、90分、空気中で加熱、酸化し、第1表に示す
物性を有する耐炎化繊維を作成した。 上記耐炎化繊維および市販のアスベストを用い
て、実施例1と同様にして摩擦材を作成した後、
それらの摩擦係数、摩耗量などの摩擦特性を測定
した。その結果を第1表に示した。 第1表から、本発明の摩擦材は、摩擦材を構成
する硫黄含有アクリル系耐炎化繊維の高い引張強
度と耐熱性を反映して、アスベストや従来の耐炎
化(酸化)繊維からなる摩擦材に比較して優れた
摩擦特性を有する摩擦材であることが判る。
[Table] was heated and baked in the same manner except that it was heated to 250℃ for 30 minutes,
A sulfur-containing acrylic flame-resistant fiber having the fiber properties shown in Table 1 was prepared. In addition, 250% of the acrylic fiber of Example 1 was also used.
The fibers were heated and oxidized at ℃ for 90 minutes in air to produce flame-resistant fibers having the physical properties shown in Table 1. After creating a friction material in the same manner as in Example 1 using the flame-resistant fibers and commercially available asbestos,
Frictional properties such as friction coefficient and amount of wear were measured. The results are shown in Table 1. From Table 1, the friction material of the present invention is a friction material made of asbestos and conventional flame-resistant (oxidized) fibers, reflecting the high tensile strength and heat resistance of the sulfur-containing acrylic flame-resistant fibers that constitute the friction material. It can be seen that this is a friction material with superior friction properties compared to .

Claims (1)

【特許請求の範囲】[Claims] 1 硫黄含有量が少なくとも3重量%である硫黄
含有アクリル系耐炎化繊維を基材とする摩擦材。
1. A friction material based on a sulfur-containing acrylic flame-resistant fiber having a sulfur content of at least 3% by weight.
JP15168086A 1986-04-14 1986-06-30 Friction material Granted JPS638424A (en)

Priority Applications (5)

Application Number Priority Date Filing Date Title
JP15168086A JPS638424A (en) 1986-06-30 1986-06-30 Friction material
PCT/JP1987/000219 WO1987006276A1 (en) 1986-04-14 1987-04-09 Sulfurized acrylic fibers with high strength and high toughness, process for their preparation, and composite material comprising them
DE19873783423 DE3783423T2 (en) 1986-04-14 1987-04-09 COMPOSITE REINFORCED WITH SULFATED ACRYLIC FIBERS.
EP87902710A EP0263884B1 (en) 1986-04-14 1987-04-09 Composite material reinforced with sulfurized acrylic fibers
US07/412,563 US5502090A (en) 1986-04-14 1989-09-25 High tenacity and high toughness acrylic sulfide fibers, a process for production thereof, and composite materials prepared by using it

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP15168086A JPS638424A (en) 1986-06-30 1986-06-30 Friction material

Publications (2)

Publication Number Publication Date
JPS638424A JPS638424A (en) 1988-01-14
JPH0355497B2 true JPH0355497B2 (en) 1991-08-23

Family

ID=15523905

Family Applications (1)

Application Number Title Priority Date Filing Date
JP15168086A Granted JPS638424A (en) 1986-04-14 1986-06-30 Friction material

Country Status (1)

Country Link
JP (1) JPS638424A (en)

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP5407083B2 (en) * 2008-12-25 2014-02-05 曙ブレーキ工業株式会社 Wet friction material

Also Published As

Publication number Publication date
JPS638424A (en) 1988-01-14

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