200540196 (1) 九、發明說明 【發明所屬之技術領域】 本發明係關於一種聚氨酯發泡體製成 製造方法。 【先前技術】 鐵軌的軌道（鐵軌），作爲減輕車輛 • 動或噪音用的防震材料，使用鐵軌用墊片 這種鐵軌用墊片包括插入鐵軌與枕木 、鋪在枕木下的枕木用墊片、鋪在鈑式軌 軌道平板用防震材料等。 這樣的鐵軌用墊片的製成材料，要习 良好的防震性能與緩衝性能而適合於使用 彈簧常數，同時要求（2)良好的壓縮特 壓縮永久變形）、（3)高的機械強度、 φ 性等。 過去，作爲鐵軌用墊片使用的材料， 發泡橡膠。然而，未發泡橡膠製成的鐵軌 彈簧常數低且柔軟的未發泡橡膠製成的鐵 足夠耐久性的墊片。 另外，爲了降低彈簧常數，在未發泡 加工等形成鐵軌用墊片時，該鐵軌用墊片 均勻，在應力集中的溝槽部産生龜裂等， 步降低。 的鐵軌用墊片之 行駛時産生的振 〇 之間的軌道墊片 道的導軌下面的 R ( 1 )爲了呈現 條件的比較低的 性（尤其是小的 (4 )足夠的耐久 使用SBR系的未 用墊片，尤其是 軌用墊片不是有 橡膠上實施溝槽 上的載重分散不 導致耐久性進一 -5- 200540196 (2) 最近，作爲鐵軌用墊片使用的材料，介紹了含多異氰 酸醋、多元醇、鏈延長劑與發泡劑的組成物發泡、硬化製 得的聚氨酯發泡體（參照特許文獻1 )。製成鐵軌用墊 片的聚氨酯發泡體利用調節密度等比較容易控制彈簧常數 ，耐久性等比未發泡橡膠製的墊片好而引人注目。 這裏’作爲發泡劑，使用水等的反應型發泡劑、氟隆 等的非反應型發泡劑。 • [特許文獻1]特開平7-268052號公報 [特許文獻2]特開平8-27241號公報 [特許文獻3]特開平8- 1 98927號公報 [特許文獻4]特開2000-281745號公報 【發明內容】 本發明所欲解決之課題 然而，鐵軌用墊片使用的上述聚氨酯發泡體有如下述 φ 的問題。 (1 )使用反應型發泡劑形成的聚氨酯發泡體，不是 均勻滿足所有適合鐵軌用墊片的低彈簧常數、良好的壓縮 特性、高機械強度的發泡體。 尤其是，作爲反應型發泡體使用水時，形成的發泡體 中所含有的尿素鍵結的比例增高，結果製得的發泡體的彈 簧常數太高（變得太硬），不能充分呈現所期望的防震性 能與緩衝性能。另外，該發泡體的壓縮特性也差（參照後 述的比較例1 - 3 )。 -6 - 200540196 (3) (2 )使用發泡劑形成的聚氨酯發泡體，其蜂窩（氣泡） 直徑大，同一墊片內不同部位的蜂窩直徑的偏差也大。因 此，各性能（尤其是彈簧常數）在不同部位的偏差增大， 該發泡體製成的鐵軌用墊片不是具有載重均勻分散性的墊 片。 (3)形成聚氨酯發泡體時，需要可耐發泡壓的堅固 的成型模。即，爲了確保鐵軌用墊片要求的尺寸精確度， φ 需要不隨發泡壓力而變形的材質和強度的成型模與鎖模裝 置。 (4 )聚氨酯發泡體由於是液態或膏態的組成物在成 型模內膨脹成型的發泡體，故在得到的發泡體的上面産生 空氣滯留，導致鐵軌用墊片的製造效率或合格率的降低。 (5 )從環境衛生方面考慮，使用氟隆或鹵化烴等作 爲發泡劑也不理想。 本發明是基於以上的問題而完成的。 φ 本發明的第1個目的在於提供均勻滿足所有適合於呈 現防震、緩衝性能的低彈簧常數、良好的壓縮特性、高機 械強度、耐久性的聚氨酯發泡體製成的鐵軌用墊片之製造 方法。 本發明的第2個目的在於提供具具有微細、不同部位 的大小的偏差少的蜂窩狀結構的聚氨酯發泡體製成的鐵軌 用墊片之製造方法。 本發明的第3個目的在於提供即使不使用高強度的成 型模也可以製造尺寸精確度高且沒有如空氣滯留之類的成 200540196 (4) 型不良的鐵軌用墊片的鐵軌用墊片之製造方法。 本發明的第4個目的在於提供環境衛生方面也理想的 鐵軌用墊片之製造方法。 本發明的第5個目的在於提供均勻滿足所有適合於呈 現防震、緩衝性能的低彈簧常數、良好的壓縮特性、高機 械強度、耐久性的聚氨酯發泡體製成的防震材料的製造方 法。 • 本發明的製造方法是製造由聚氨酯發泡體製成的鐵軌 用墊片的方法，其特徵在於，經由在惰性氣體的環境下， 將含有（A) MDI系異氰酸酯與多元醇反應製得的NCO終 端預聚體、（B1)平均官能基數2.0-4.0、數平均分子量 爲1，000-6,000的多元醇、（B2)官能基數2-4、分子量 爲6〇〇以下的鏈延長劑、莫耳比（[NCO]/[OH])爲0.80-1 ·2〇的組成物（以下稱“尿烷形成性組成物”）進行機械 攪拌’使惰性氣體分散在該尿烷形成性組成物中調製泡沫 ♦ 狀的原料，將該原料注入成型模中使其硬化，形成製成鐵 軌用墊片的聚氨酯發泡體。 本發明的製造方法中，使惰性氣體與該尿烷形成性組 成物接觸’在常壓下或〇.5Mpa以下的加壓下進行機械攪 拌，調製密度〇.3-l.〇g/cm3、平均蜂窩直徑爲1 -200μιη的 泡沬狀的原料，使該原料在成型模內硬化爲佳。 另外’水在尿院形成性組成物中的含有比例未達0.1 質量％爲佳。 此外’本發明的製造方法是製造由聚氨酯發泡體製成 -8 - 200540196 (5) 的防震材料的方法，其特徵在於’經過在惰性氣體的環境 下將尿烷形成性組成物進行機械攪拌，使惰性氣體分散在 該尿烷形成性組成物中調製泡沬狀的原料，將該原料注人 成型模中使其硬化，形成製成防震材料的聚氨酯發泡體。 本發明之效果 (1 )依據本發明的製造方法，可以製造均勻滿足所 • 有適合於呈現防震、緩衝性能的低彈簧常數（柔軟性）、 良好的壓縮特性（尤其是，小的壓縮永久變形）、高的機 械強度、耐久性全部平衡的聚氨酯發泡體製成的鐵軌用墊 (2 )依據本發明的製造方法，可以製造具有微細（ 平均蜂窩直徑= 1 -200μιη)且不同部位的大小的偏差少的蜂 窩狀結構的聚氨酯發泡體製成的鐵軌用墊片，這樣的鐵軌 用墊片，各性能（特別是彈簧常數）的不同部位的偏差小 • ，載重的均勻分散性好。 (3 )依據本發明的製造方法，即使使用不需要高強 度的簡易的成型模，也可以製造尺寸精確度高的鐵軌用墊 片。 (4 )依據本發明的製造方法，可以製造沒有空氣滯 留之類的成型不良的鐵軌用墊片，可以實現鐵軌用墊片製 造效率的提高。 (5 )本發明的製造方法，由於不使用氟隆或鹵化烴 等，故在環境衛生方面也很理想。 -9- 200540196 (6) 本發明所欲實施之最佳形態 <尿烷形成性組成物> 本發明的製造方法使用的尿烷形成性: MDI系異氰酸酯與多元醇反應製得的NCO 以下，稱“ NCO終端預聚體（A ));平均 〜4.0、數平均分子量1,000〜6，000的多元 • 多元醇（B1) ) •，官能基數2〜4、分子量 延長劑（以下，稱“鏈延長劑（B2 ))，基 泡劑（反應型反泡劑/非反應型發泡劑）。 <NCO終端預聚體（A) > 製成尿烷形成性組成物的N C Ο終端預赛 MDI系異氰酸酯與多元醇反應製得。 於此，“ MDI系異氰酸酯”包括MDI ( # 合型MDI (三聚體以上的多聚體）。 作爲爲了獲得NCO終端預聚體（A ) f 與聚合型MDI的比例，30〜100:70〜0爲4 〜100:60-0 〇 另外，所使用的MDI有4,4’ — MDI、2 2,2’ 一 MDI的異構體，4,4’ — MDI的比例 佳。 作爲爲了獲得N C Ο終端預聚體（A )所 ，可列舉聚醚二醇、聚酯二醇、聚碳酸酯二 组成物，含有 終端預聚體（ 官能基數2.0 醇（以下，稱 6 〇 〇以下的鏈 本上不含有發 I體（A )，使 二聚體）與聚 听使用的MDI 圭、再佳是4 0 、4’ 一 MDI 與 是70%以上爲 使用的多元醇 醇等的二元醇 -10- 200540196 (7) 作爲爲了獲得N C Ο終端預聚體（A )所使用的聚醚二 醇，可舉出聚氧化乙二醇（PEG )、聚氧化丙二醇（PPG )、聚氧化四甲二醇（PTMG );以脂肪族二醇（例如， 乙二醇、1，3-丁二醇、i，4-丁二醇、二乙二醇、二丙二醇 ，：1，2-丙二醇、1，3-丙二醇）爲引發劑使環式醚（例如， 環氧乙烷、環氧丙烷、氧雜環丁烷、四氫呋喃）開環聚合 φ 製造的聚醚多元醇，這些可以單獨使用或可以將2種以上 組合使用。 作爲爲了獲得NCO終端預聚體（A )所使用的聚酯二 醇，可舉出聚（乙烯己二酸酯）二醇、聚（丙烯己二酸酯 )二醇、聚（乙烯一丙烯己二酸酯）二醇、聚（丁烯己二 酸酯）二醇、聚（己烯己二酸酯）二醇；使乙二醇、丙二 醇、己二酸聚縮合製造的共聚酯二醇[例如聚（丁烯-乙 烯己二酸酯）二醇、聚（1，4-丁烯一丙烯己二酸酯）二醇 Φ 、及聚（1，4-丁烯一乙烯一丙烯己二酸酯）二醇];己內酯 和/或二羧酸（例如其中琥珀酸、丙二酸、庚二酸、癸二 酸與辛二酸）與低分子量二醇[例如，與作爲鏈延長劑（ B2 )使用的低分子量二醇相同的化合物]聚縮合製造的聚 酯二醇，這些可以單獨使用，也可以將2種以上組合使用 〇 作爲爲了獲得NCO終端預聚體（A )所使用的聚碳酸 酯二醇，可舉出使低分子量的碳酸酯與低分子量二醇反應 (脫醇聚縮合反應）製得的聚碳酸酯二醇’可以使用1種 -11 - 200540196 (8) 或將2種以上組合使用。 作爲爲了得到聚碳酸酯二醇所使用的低分子量的碳酸 酯’可列舉二烷基碳酸酯（例如二乙基碳酸酯）、亞烷基 碳酸酯（例如二乙烯碳酸酯）、二苯基碳酸酯等。 作爲爲了得到聚碳酸酯二醇所使用的低分子量二醇， 可舉出與作爲鏈延長劑（B2 )使用的低分子量二醇相同的 化合物。 • NCO終端預聚體（A)，可以經過將MDI系異氰酸酯 與多元醇混合、對該混合物加熱進行尿烷化反應製得。此 外，該混合物中在不破壞本發明效果的範圍內也可以含有 其他種類的多異氰酸酯或鏈延長劑。 這裏，作爲其他種類的聚異氰酸酯，可列舉亞苯基二 異氰酸酯、2,4-甲苯二異氰酸酯（2,4-TDI ) 、2,6-甲苯二 異氰酸酯（2,6-TDI )等的芳香族異氰酸酯類，丁烯二異 氰酸酯、己烯二異氰酸酯（HDI)等的脂肪族二異氰酸酯 Φ ，異佛爾酮二異氰酸酯、氫化TDI、氫化MDI等的脂環族 二異氰酸酯等，這些可以單獨使用或將2種以上組合使用 〇 另外，作爲混合物中所含有的鏈延長劑，可舉出與作 爲鏈延長劑（B2 )使用的低分子量二醇相同的化合物。 作爲NCO終端預聚體（A)的NCO含量，3〜34質量 %爲佳、更佳是4〜1 6質量％。 NCO含量不足3質量％時，該預聚體的粘度太高，與 多元醇（B 1 )的混合性差，導致製造效率降低。 -12- 200540196 (9) 而NCO含量超過34質量％時，該預聚體的貯存穩定 性可能惡化。 另外，作爲NCO終端預聚體（A )的平均官能基數， 2.0〜3.5爲佳，更佳是2.0〜2.5。 平均官能基數不足2.0時，製得的聚氨酯發泡體（鐵 軌用墊片）不能成爲具有良好的壓縮特性或高機械強度的 墊片。 B 而平均官能基數超過3.5時，容易引起凝膠化，穩定 性差。 <多元醇（B1 ) > 製成尿烷形成性組成物的多元醇（B 1 )，是平均官能 基數爲2.0-4.0、數平均分子量爲1，〇〇〇〜6,000的多元醇 〇 這裏，作爲適用的多元醇（B 1 )，可列舉聚醚多元醇 φ 與聚醋多元醇。 作爲製成多元醇（B1)的「聚醚多元醇」，可列舉公 稱平均官能基數2.0〜4.0的聚氧化乙烯多元醇、聚氧化丙 烯多元醇、聚氧化丁烯多元醇；以有2〜4個活性氫的化 合物爲引發劑，使環式醚與該化合物加成製造的聚醚多元 醇。 作爲用來製造聚醚多元醇的有『2〜4個活性氫的化合 物』，可列舉乙二醇、1，2-丙二醇、1，3-丙二醇、2,2-二甲 基-1，3-丙二醇、1,3-丁 二醇、丁二醇、1，5-戊二醇、 -13- 200540196 (10) 1，6 -己二醇、二乙二醇、二丙二醇、三甲撐二醇、三乙二 醇、四甲撐二醇、六甲撐二醇、十甲撐二醇、新戊二醇、 3 -甲基-1，5 -戊二醇、雙酚A等的低分子量二醇；丙三醇、 己三醇、三羥甲基丙烷等的低分子量三醇；季戊四醇等的 低分子量多元醇；乙二胺、丙二胺等的脂肪族二胺；苯二 胺、甲苯二胺、二甲苯二胺二苯基甲烷二胺等的芳香族二 胺；苯胺等的芳香族胺；一乙醇胺、二乙醇胺、三乙醇胺 φ 等的低分子胺醇；四羥甲基環己烷；甲基葡糖苷等，這些 可以單獨使用或2種以上組合使用。 作爲供於製造聚醚多元醇的“環式醚”，可舉出環氧 乙烷、環氧丙烷、環氧丁烷、氧雜環丁烷、四氫呋喃等。 作爲製成多元醇（B1)的「聚酯多元醇」，可舉出有 2個以上羥基的化合物（多元醇）與有2個以上羧基的化 合物（多元酸）採用公知的方法反應製造的聚酯多元醇。 作爲供於製造聚酯多元醇的有『2個以上羥基的化合 φ 物（多元醇）』，可列舉該低分子量二醇與低分子量三醇 ，這些可以單獨使用或2種以上組合使用。 作爲供於製造聚酯多元醇的有『2個以上羧基的化合 物（多元酸）』，可列舉己二酸、丙二酸、琥珀酸、酒石 酸、庚二酸、癸二酸、乙二酸、鄰苯二甲酸、對苯二甲酸 、間苯二甲酸、鄰苯二甲酸酐、壬二酸、偏苯三酸、戊烯 二酸、α -氫化粘糠酸、β -氫化粘糠酸、α - 丁基-α -乙基戊二 酸，α，β -二乙基琥珀酸、半燈酸、1，4 ·環己烷二羧酸、2，6 _ 萘二羧酸、4,4，-聯苯二羧酸、4,4’ -二苯醚二羧酸，4,4 -14- 200540196 (11) ，-二苯基甲烷二羧酸，4,4 ’ -二苯楓二羧酸、4， 基異丙叉二羧酸、1，2-二苯氧基乙烷_4’ ，4” -二 二羧酸、2，5 -吡啶二羧酸、二苯酮二羧酸等，這 獨使用或2種以上組合使用。 多元醇（B1)的平均官能基數爲2.0〜4.0、 爲佳。 多元醇的平均官能基數不足2 · 0時，製得的 φ 泡體不能成爲有高機械強度（拉伸強度、撕裂強 好壓縮特性（低的壓縮永久變形）的發泡體。 而多元醇的平均官能基數超過4.0時，製得 發泡體的彈簧常數太高，不能充分發揮作爲防震 料的性能。 多元醇（B1)的數平均分子量爲1，0〇〇〜 1，000〜3,000 爲佳。 多元醇的數平均分子量不足1，000時，製得 • 的彈簧常數太高，不能充分發揮作爲防震、緩衝 會b 。 而多元醇的數平均分子量超過6,000時，製 酯發泡體不能成爲有高機械強度（拉伸強度、撕f 與良好壓縮特性（低的壓縮永久變形）的發泡體， <鏈延長劑（B2 ) > 製成尿烷形成性組成物的鏈延長劑（B2 )， 數2〜4、分子量600以下的鏈延長劑。 4，-二苯 羧酸、蒽 些可以單 2.5 〜3.5 聚氨酯發 度）與良 的聚氨酯 、緩衝材 c 6，0 〇 〇， 的發泡體 材料的性 得的聚氛 裂強度） 是官能基 -15- 200540196 (12) 這裏，作爲鏈延長劑（B 2 )，可舉出乙 醇、三乙二醇、丙二醇、二丙二醇、丨，4 _ 丁 二醇、新戊二醇等的低分子量二醇，丙三醇、三 院、二經甲基乙院、己三醇等的低分子量三醇， 的低分子量四醇等。 鏈延長劑（B2 )的分子量爲600以下。 鏈延長劑的分子量超過600時，製得的聚氨 φ 不能成爲有高機械強度（拉伸強度、撕裂強度） 縮特性（低的壓縮永久變形）的發泡體。 <尿烷形成性組成物的任意成分> 本發明製造方法使用的尿烷形成性組成物， 終端預聚體（A)、多元醇（B1)與鏈延長劑（ 須成分，但也可以含有這些以外的成分。 作爲這樣的任意成分，可列舉催化劑、整泡 φ 劑（顔料、染料）、抗氧劑與紫外線吸收劑等。 尿烷形成性組成物中水的含有比例不足〇· 1 佳、更佳是不足0.05質量％。 因此，限制尿院鍵的形成’結果可以製造有 軌用墊片的低彈簧常數與良好的壓縮特性（尤其 壓縮永久變形）的聚氨酯發泡體。 <尿烷形成性組成物的莫耳比（[NC0]/[0H]) 本發明的製造方法使用的尿烷形成性組成物 、二乙二 、1，6-己 羥甲基丙 雙甘油等 酯發泡體 與良好壓 含有NCO B 2 )爲必 劑、著色 質量％爲 適合於鐵 是，小的 ，從確保 -16- 200540196 (13) 良好的硬化性的觀點考慮，異氰酸酯基與羥基的莫耳比（ [NC0]/[0H])爲 0.8 0- 1.20，0.90-1.10 爲佳。 <聚氨酯發泡體的形成> 本發明的製造方法，其特徵在於，經過在惰性氣體的 環境下將上述的尿烷形成性組成物進行機械攪拌，使惰性 氣體分散在該尿院形成性組成物中調製泡沬狀的原料，將 該原料注入成型模中使之硬化’形成製成鐵軌用墊片的聚 氨酯發泡體。 這裏，如上述地採用機械攪拌使惰性氣體分散在尿烷 形成性組成物中調製泡沬狀原料的方法稱作機械泡沫發泡 法。 經過採用機械泡沬發泡法，可以製造具具有微細（平 均蜂窩直徑=1〜200μπι )、且同一個墊片內不同部位的大 小的偏差少的蜂窩狀結構的聚氨酯發泡體（載重均勻分散 ^ 性好的鐵軌用墊片）。 這樣的微細且均勻的蜂窩狀結構，無法採用使用發泡 劑（反應型發泡劑/非反應型發泡劑）的以往的製造方法 形成。 這裏，使尿烷形成性組成物進行機械泡沬發泡的步驟 中，使惰性氣體與該組成物接觸，在常壓下或0.5MPa以 下的加壓下進行機械攪拌（提供剪切力）’使該惰性氣體 的粒子（氣泡）均勻分散，調製密度爲〇·3〜1 ·0§/〇ηι3、 平均蜂窩直徑爲1〜200μιη的泡沫狀的原料（未硬化的組 -17- 200540196 (14) 成物）’在成型模內使該原料硬化爲佳。 這裏，機械攪拌在常壓下或〇 . 5 Μ P a以下的加壓下進 行爲佳。在超過〇.5MPa的加壓下進行機械攪拌時，由於 模頭出口産生的壓力急劇釋放，有時混合泡（分散的惰性 氣體）産生破泡。 由於機械泡沬發泡製得的原料（未硬化的組成物）是 泡沫狀，故實際上不需要考慮成型模內的發泡壓。因此， φ 注入該原料的成型模不需要如水發泡體系所使用的成型模 那樣的高強度，可以使用簡易的成型模。因此，使用這樣 的簡易成型模，可以確保製造尺寸精確度高、沒有如空氣 滯留之類的成型不良的鐵軌用墊片。 <聚氨酯發泡體> 製成本發明製造的鐵軌用墊片的聚氨酯發泡體的密度 爲 0.3 〜1.0g/cm3、佳爲 0.5 〜0.9g/cm3。 φ 密度不足0.3 g/cm3的聚氨酯發泡體，不能成爲有足 夠的機械強度的發泡體。而密度超過l.〇g/cm3的聚氨酯發 泡體，彈簧常數太高，不能充分發揮作爲防震、緩衝材料 的性能。 製成鐵軌用墊片的聚氨酯發泡體的平均蜂窩直徑爲1 〜200μιη、佳爲 5〜120μηι。 平均蜂窩直徑不足1 μηι的聚氨酯發泡體’與未發泡體 同樣，不能發揮發泡體所要求的性能。而平均蜂窩直徑超 過2 00 μηι的聚氨酯發泡體不能成爲有均勻物性的發泡體。 -18- 200540196 (15) 製成鐵軌用墊片的聚氨酯發泡體，由於具有微細（平 均蜂窩直徑=1〜2 0 0 μ m )、且不同部位的大小的偏差少的 蜂窩狀結構，故鐵軌用墊片所要求的性能（尤其是彈簧常 數）在不同部位的偏差小，因此，載重的均勻分散性好。 製成鐵軌用墊片的聚氨酯發泡體的彈簧常數佳爲3〜 6 0MN/m、更佳爲4〜30 MN/m、特別佳爲5〜1 5MN/m。 這種彈簧常數太小的聚氨酯發泡體不能成爲有足夠的 φ 機械強度的發泡體。 而彈簧常數太大的聚氨酯發泡體，不能充分發揮作爲 防震、緩衝材料的性能。 這種製成的聚氨酯發泡體由於有優異的防震性能與緩 衝性能，故也可以作爲鐵軌用墊片以外的防震材料使用。 【實施方式】 實施例 φ 以下，對本發明的實施例進行說明，但本發明不限於 這些實施例。下面的比率爲質量基準。 <合成例1> 依據下述表1所示的配方，於容量100OmL備有攪拌 機、冷卻管、氮氣導入管與溫度計的反應容器中’加入 MDI (以1質量％以下的比例含有2,2，-MDI與2,4’ - MDI組成的異構體混合物，以99質量％以上的比例含有 4,4’ -MDI的二苯基甲烷二異氰酸酯）100.0質量份、多 -19- 200540196 (16) 元醇（i)[公稱平均官能基數=2、數平均分子量=2，Ο 〇 〇的聚 (氧化四甲烯）多元醇]166.2質量份，在80T：下攪拌4小 時進行尿烷化反應，製得NCO含量10.0質量％的NC0終 端預聚體（A )(以下，稱作“預聚體（A-1 ) ” ) ° <合成例2> 依據下述表1所示的配方，除了將多元醇（i )的加 φ 入量改成270.6質量份以外，其他與合成例1同樣地進行 尿烷化反應，製得NCO含量6.0質量°/。的NCO終端預聚 體（A )(以下，稱“預聚體（Α·2 ) ” )。 <合成例3> 依據下述表1所示的配方，除了把多元醇（i)的加入量 改成56.2重量份以外，其他與合成例1同樣地進行尿烷 化反應，製得NCO含量20.0質量％的NCO終端預聚體（ φ 以下，稱“預聚體（a-1)，，）。 <合成例4> 依據下述表1的配方，除了把多元醇（i )的加入量 改成96.9質量份以外，其他與合成例1同樣地進行尿烷 化反應，製得NCO含量15.0質量％的NCO終端預聚體（ 以下，稱“預聚體（a-2) ” ）。 <合成例5> -20- 200540196 (17) 依據下列表1所示的配方，除了加入多元醇（Η)[公稱 平均官能基數=2 ’數平均分子量=1，000的聚（氧化四甲烯 )多元醇]65 ·8質量份替代多元醇⑴以外，其他與合成例 1同樣地進行尿烷化反應，製得NC〇含量17.0質量。/◦的 N C Ο終端預聚體（以下，稱“預聚體（a _ 3 )，，)。 表1 合成例1 合成例2 合成例3 合成例4 合成例5 預聚體 A-1 A-2 a-1 a-2 a-3 MDI 100.0 100.0 100.0 100.0 100.0 多元醇(i) 166.2 270.6 56.2 96.9 多元醇(ii) • - 65.8 NCO含量[質量％] 10.0 6.0 20.0 15.0 17.0 M D I:以1質量％以下的比例含有2，2，- M D I與2，4 ’ -MDI組成的異構體混合物，以99質量％以上的比例含 # 有4,4’ -MDI的二苯基甲烷二異氰酸酯 *多元醇（i):公稱平均官能基數=2、數平均分子量 =2，000的聚（氧化四甲烯）多元醇 *多元醇（ii):公稱平均官能基數=2，數平均分子量 =1，000的聚（氧化四甲烯）多元醇 <混合例1> 依據下述表2所示的配方’經過將多元醇（1 )[公稱 平均官能基數=2、數平均分子量=2,0 〇〇的聚（氧化四甲烯 -21 - 200540196 (18) )多元醇]7 5 · 4質量份、和多元醇（3 )[公稱平均官能基 數=3、數平均分子量=3,〇〇〇的聚（氧化丙烯）多元醇 ]24.6質量份、1，4-丁二醇9.3質量份、整泡劑（有機脂肪 酸酯類）0 · 5質量份、錫系催化劑（D Ο TD L ) 0 · 0 0 2質量份 進行混合，製得多元醇混合物（以下，稱“多元醇混合物 (B -1 )，，)。 φ <混合例2> 依據下述表2所示的配方，經過將多元醇（2 )[公稱 平均官能基數=2、數平均分子量=1500的聚（氧化四甲烯 )多元醇]75.4質量份、與多元醇（3) 24.6質量份、1，4_ 丁二醇9.3質量份、整泡劑〇·5質量份、和錫系催化劑 〇·〇〇2質量份進行混合，製得多元醇混合物（以下，稱“ 多元醇混合物（Β-2 ) ” ）。 • <混合例3> 依據下述表2所示的配方，經過將多元醇（3 ) 1 〇 〇 · 〇 質量份，與1，4-丁二醇20.0質量份、整泡劑〇·5質量份、 錫系催化劑0.002質量份進行混合，製得多元醇混合物（ 以下，稱“多元醇混合物（Β_3)” ）。 〈比較混合例1 > 依據下述表2所示的配方，經過將多元醇（〇 1〇〇 〇 質量份、與乙二醇〗6.0質量份、胺系催化劑（三乙烯二 -22- 200540196 (19) 胺）. 8質量份、水（反應型發泡劑）0.7質量份進行混合 ，製得多元醇混合物（以下，稱“多元醇混合物（b-Ι )” ） <比較混合例2> 依據下述表2所示的配方，經過將多元醇（3 ) 100.0 質量份，與乙二醇13.5質量份、錫系催化劑0.03質量份 、胺系催化劑0.15質量份、水0.5質量份進行混合，製得 多元醇混合物（以下稱“多元醇混合物（b-2)” ）。200540196 (1) IX. Description of the invention [Technical field to which the invention belongs] The present invention relates to a method for manufacturing a polyurethane foam. [Previous technology] Rails (rails) of rails are used as shock-proof materials to reduce vehicle movement or noise. Rail gaskets include rail gaskets and sleepers, sleeper gaskets under the sleepers, Shock-proof materials used on flat rails. The material for such a rail gasket is suitable for the use of a spring constant to acquire good shock resistance and cushioning properties, and requires (2) good compression and compression permanent set), (3) high mechanical strength, φ Sex, etc. Conventionally, foamed rubber has been used as a material for rail gaskets. However, rails made of unfoamed rubber have low spring constants and soft irons made of unfoamed rubber are sufficiently durable gaskets. In addition, in order to reduce the spring constant, when a rail gasket is formed without being subjected to a foaming process or the like, the rail gasket is uniform, and cracks or the like are generated in a groove portion where stress is concentrated, which is reduced step by step. R (1) under the guide rail of the track pad track between the vibration generated during the running of the rail shim. In order to show the relatively low performance of the condition (especially the small (4) is durable enough to use SBR series Unused shims, especially rail shims are not rubberized. Load dispersion on the grooves does not result in durability. -5- 200540196 (2) Recently, the materials used for rail shims have been introduced. Polyurethane foam produced by foaming and hardening a composition of cyanate vinegar, polyol, chain extender, and foaming agent (see Patent Document 1). Polyurethane foam made of rail gaskets is used to adjust density, etc. It is relatively easy to control the spring constant, and the durability is better than the non-foamed rubber gasket, which attracts attention. Here, as the foaming agent, a reactive foaming agent such as water, and a non-reactive foaming agent such as fluorine are used. [Patent Document 1] JP 7-268052 [Patent Document 2] JP 8-27241 [Patent Document 3] JP 8-1 98927 [Patent Document 4] JP 2000-281745 No. [Summary of the Invention] However, the above-mentioned polyurethane foam used in rail gaskets has the following problems: φ. (1) Polyurethane foams formed using reactive foaming agents do not uniformly satisfy all low spring constants suitable for rail gaskets. , Foam with good compressive properties and high mechanical strength. In particular, when water is used as a reactive foam, the proportion of urea bonds contained in the formed foam is increased, and the resulting foam is produced. The spring constant is too high (becomes too hard) and cannot sufficiently exhibit the desired shock resistance and cushioning properties. In addition, the compression characteristics of the foam are also poor (see Comparative Examples 1 to 3 described later). -6-200540196 (3) (2) Polyurethane foam formed by using a foaming agent has a large honeycomb (bubble) diameter and a large variation in honeycomb diameter in different parts of the same gasket. Therefore, each property (especially the spring constant) is The deviation of different parts increases, and the gasket for rails made of this foam is not a gasket with uniform load dispersion. (3) When forming a polyurethane foam, a strong molding die that can resist foaming pressure is required. That is, in order to ensure the required dimensional accuracy of the rail gasket, φ needs a molding die and a clamping device of a material and strength that do not deform with the foaming pressure. (4) The composition of the polyurethane foam is liquid or paste. The foam is expanded and molded in the molding die, so air stagnation occurs on the obtained foam, resulting in a reduction in the manufacturing efficiency or the qualification rate of the rail gasket. (5) From the perspective of environmental sanitation, the use of fluorine It is also not ideal as a foaming agent for halogens, halogenated hydrocarbons, etc. The present invention has been completed based on the above problems. Φ The first object of the present invention is to provide a low spring constant, good, uniformity that satisfies all requirements for shock resistance and cushioning performance. Manufacturing method of rail gasket made of polyurethane foam with high compression characteristics, high mechanical strength and durability. A second object of the present invention is to provide a method for manufacturing a gasket for rails made of a polyurethane foam having a honeycomb structure having a fine and small size variation at different locations. A third object of the present invention is to provide a rail washer for a rail, which can manufacture a rail washer having a defect of 200540196 (4) type having high dimensional accuracy without using a high-strength molding die. Production method. A fourth object of the present invention is to provide a method for manufacturing a gasket for a railroad track, which is also desirable in terms of environmental sanitation. A fifth object of the present invention is to provide a method for manufacturing a shock-resistant material made of a polyurethane foam that satisfies all low spring constants, good compression characteristics, high mechanical strength, and durability suitable for exhibiting shock-proof and cushioning properties. • The manufacturing method of the present invention is a method for manufacturing a rail gasket made of polyurethane foam, which is characterized by reacting (A) an MDI-based isocyanate with a polyol in an inert gas environment. NCO-terminated prepolymer, (B1) a polyol with an average number of functional groups of 2.0-4.0, a number average molecular weight of 1,000-6,000, (B2) a number of functional groups of 2-4, a chain extender with a molecular weight of 600 or less, Mo A composition having an ear ratio ([NCO] / [OH]) of 0.80-1.20 (hereinafter referred to as "urethane-forming composition") is mechanically stirred to disperse an inert gas in the urethane-forming composition. A foam-shaped raw material is prepared, and the raw material is poured into a molding die and hardened to form a polyurethane foam which is used as a rail gasket. In the manufacturing method of the present invention, an inert gas is brought into contact with the urethane-forming composition to be mechanically stirred at a normal pressure or a pressure of 0.5 MPa or less to adjust the density of 0.3 to 1.0 g / cm3, A foam-like raw material having an average honeycomb diameter of 1 to 200 μm is preferably hardened in a molding die. The content of 'water in the urinary-forming composition is preferably less than 0.1% by mass. In addition, the manufacturing method of the present invention is a method for manufacturing a shock-proof material made of polyurethane foam-8-200540196 (5), which is characterized by 'mechanically stirring a urethane-forming composition in an inert gas environment. An inert gas is dispersed in the urethane-forming composition to prepare a foam-like raw material, and the raw material is injected into a molding die and hardened to form a polyurethane foam made of a shock-proof material. Effects of the present invention (1) According to the manufacturing method of the present invention, it is possible to manufacture uniformly satisfying all requirements • Low spring constant (flexibility) suitable for showing shock resistance and cushioning performance, good compression characteristics (especially, small permanent compression deformation) ), Rail pads (2) made of polyurethane foam with a high balance of mechanical strength and durability, according to the manufacturing method of the present invention, it is possible to produce micro parts (average honeycomb diameter = 1-200 μιη) and the size of different parts • Gaskets for rails made of polyurethane foam with a honeycomb structure with less deviation. Such rails have less deviation in different parts of each performance (especially spring constant), and good uniformity of load dispersion. (3) According to the manufacturing method of the present invention, even if a simple molding die that does not require high strength is used, a rail pad having high dimensional accuracy can be manufactured. (4) According to the manufacturing method of the present invention, it is possible to manufacture rail shims without defective molding such as air stagnation, and it is possible to improve the manufacturing efficiency of rail shims. (5) The production method of the present invention is also ideal in terms of environmental sanitation because it does not use fluorine or halogenated hydrocarbons. -9- 200540196 (6) The best form to be implemented in the present invention < urethane-forming composition > The urethane-forming property used in the production method of the present invention: NCO or less obtained by the reaction of MDI-based isocyanate and polyol , Called “NCO-terminated prepolymer (A)); Polyols with an average of ~ 4.0 and a number average molecular weight of 1,000 to 6,000 • Polyols (B1)) •, with a functional number of 2 to 4, and molecular weight extenders (hereinafter, referred to as“ Chain extender (B2)), base foaming agent (reactive defoaming agent / non-reactive foaming agent). < NCO terminal prepolymer (A) > An N C 0 terminal preliminary test for a urethane-forming composition is prepared by reacting an MDI-based isocyanate with a polyol. Here, the "MDI-based isocyanate" includes MDI (# -combined MDI (multimer of a trimer or higher). As a ratio for obtaining an NCO-terminated prepolymer (A) f to a polymerized MDI, 30 to 100: 70 ～ 0 is 4 ～ 100: 60-0 〇 In addition, the MDI used is 4,4 ′ — MDI, 2 2,2 ′ —MDI isomers, and the ratio of 4,4 ′ — MDI is good. The NC Ο terminal prepolymer (A) includes polyether diol, polyester diol, and polycarbonate, and includes a terminal prepolymer (functional group: 2.0 alcohol (hereinafter, referred to as a chain below 600)). This product does not contain the dimer (A), which is a dimer), and MDI, which is used for polyphony, and even more preferably 40, 4'-MDI and 70% or more of the diols used, such as polyols. -10- 200540196 (7) Examples of the polyether diol used to obtain the NC 0 terminal prepolymer (A) include polyethylene oxide (PEG), polypropylene oxide (PPG), and polytetramethylene oxide. Glycol (PTMG); aliphatic diols (eg, ethylene glycol, 1,3-butanediol, i, 4-butanediol, diethylene glycol, dipropylene glycol, 1,2-propylene glycol, 1 , 3- Propylene glycol) is a polyether polyol produced by the ring-opening polymerization of cyclic ethers (eg, ethylene oxide, propylene oxide, oxetane, and tetrahydrofuran) by an initiator. These can be used alone or in combination of two or more kinds. Used in combination. Examples of the polyester diol used to obtain the NCO-terminated prepolymer (A) include poly (ethylene adipate) diol, poly (propylene adipate) diol, and poly (ethylene Monopropylene adipate) diol, poly (butene adipate) diol, poly (hexaene adipate) diol; copolymerization produced by polycondensation of ethylene glycol, propylene glycol, and adipic acid Ester diols [e.g. poly (butene-ethylene adipate) diol, poly (1,4-butene-propylene adipate) diol Φ, and poly (1,4-butene-ethylene adipate) Propylene adipate) diols]; caprolactone and / or dicarboxylic acids (such as succinic acid, malonic acid, pimelic acid, sebacic acid and suberic acid) and low molecular weight diols [e.g., and The same compound as the low-molecular-weight diol used as the chain extender (B2)] a polyester diol produced by polycondensation, these can be used alone or Two or more kinds are used in combination. As the polycarbonate diol used to obtain the NCO-terminated prepolymer (A), a method in which a low molecular weight carbonate is reacted with a low molecular weight diol (dealcoholization polycondensation reaction) can be mentioned. The obtained polycarbonate diol can be used -11-200540196 (8) or a combination of two or more kinds. Examples of the low-molecular-weight carbonate used to obtain the polycarbonate diol include dialkyl carbonates. Esters (such as diethyl carbonate), alkylene carbonates (such as diethylene carbonate), diphenyl carbonate, and the like. Examples of the low molecular weight diol used to obtain the polycarbonate diol include the same compounds as the low molecular weight diol used as the chain extender (B2). • NCO-terminated prepolymer (A) can be prepared by mixing MDI-based isocyanate with polyol and heating the mixture for urethane reaction. In addition, the mixture may contain other kinds of polyisocyanates or chain extenders as long as the effects of the present invention are not impaired. Here, examples of other types of polyisocyanates include aromatics such as phenylene diisocyanate, 2,4-toluene diisocyanate (2,4-TDI), and 2,6-toluene diisocyanate (2,6-TDI). Isocyanates, aliphatic diisocyanates such as butene diisocyanate, hexene diisocyanate (HDI) Φ, alicyclic diisocyanates such as isophorone diisocyanate, hydrogenated TDI, hydrogenated MDI, etc., these can be used alone or Two or more types are used in combination. Examples of the chain extender contained in the mixture include the same compounds as the low-molecular-weight diol used as the chain extender (B2). The NCO content of the NCO terminal prepolymer (A) is preferably 3 to 34% by mass, more preferably 4 to 16% by mass. When the NCO content is less than 3% by mass, the viscosity of the prepolymer is too high, the miscibility with the polyol (B 1) is poor, and the production efficiency is lowered. -12- 200540196 (9) When the NCO content exceeds 34% by mass, the storage stability of the prepolymer may deteriorate. The average number of functional groups of the NCO-terminated prepolymer (A) is preferably 2.0 to 3.5, and more preferably 2.0 to 2.5. When the average number of functional groups is less than 2.0, the obtained polyurethane foam (gasket for rails) cannot be a gasket having good compression characteristics or high mechanical strength. B. When the average number of functional groups exceeds 3.5, gelation is liable to occur and the stability is poor. < Polyol (B1) > Polyol (B1) which is a urethane-forming composition is a polyol having an average number of functional groups of 2.0 to 4.0 and a number average molecular weight of 1,000 to 6,000. Here As suitable polyols (B 1), polyether polyols φ and polyester polyols can be mentioned. As the "polyether polyol" made of the polyol (B1), polyoxyethylene polyols, polyoxypropylene polyols, and polybutylene oxide polyols having a nominal average number of functional groups of 2.0 to 4.0 can be cited; A polyether polyol produced by adding an active hydrogen compound as an initiator to a cyclic ether and the compound. Examples of the "2 to 4 active hydrogen compounds" used in the production of polyether polyols include ethylene glycol, 1,2-propanediol, 1,3-propanediol, and 2,2-dimethyl-1,3. -Propylene glycol, 1,3-butanediol, butanediol, 1,5-pentanediol, -13- 200540196 (10) 1,6-hexanediol, diethylene glycol, dipropylene glycol, trimethylene glycol Molecular weight low-molecular-weight diols, such as triethylene glycol, tetramethylene glycol, hexamethylene glycol, decamethylene glycol, neopentyl glycol, 3-methyl-1,5-pentanediol, bisphenol A, etc. ; Low molecular weight triols such as glycerol, hexanetriol, and trimethylolpropane; low molecular weight polyols such as pentaerythritol; aliphatic diamines such as ethylenediamine and propylenediamine; phenylenediamine and toluenediamine , Xylene diamine diphenylmethane diamine and other aromatic diamines; aromatic amines such as aniline; monoethanolamine, diethanolamine, triethanolamine φ and other low molecular amine alcohols; tetramethylolcyclohexane; These can be used alone or in combination of two or more. Examples of the "cyclic ether" for use in the production of polyether polyols include ethylene oxide, propylene oxide, butylene oxide, oxetane, and tetrahydrofuran. Examples of the "polyester polyol" to be used for the polyol (B1) include a polymer (polyol) having two or more hydroxyl groups and a compound (polyacid) having two or more carboxyl groups produced by a known method. Ester polyol. Examples of the "compound φ compound (polyol) having two or more hydroxyl groups" for producing a polyester polyol include the low molecular weight diol and the low molecular weight triol. These can be used alone or in combination of two or more. Examples of the "compound (polyacid) having two or more carboxyl groups" for producing polyester polyols include adipic acid, malonic acid, succinic acid, tartaric acid, pimelic acid, sebacic acid, oxalic acid, Phthalic acid, terephthalic acid, isophthalic acid, phthalic anhydride, azelaic acid, trimellitic acid, glutaric acid, α-hydrofuroic acid, β-hydrofuroic acid, α -Butyl-α-ethylglutaric acid, α, β-diethylsuccinic acid, semi-lamp acid, 1,4-cyclohexanedicarboxylic acid, 2,6 _ naphthalenedicarboxylic acid, 4,4, -Biphenyldicarboxylic acid, 4,4'-diphenyl ether dicarboxylic acid, 4,4 -14- 200540196 (11), -diphenylmethanedicarboxylic acid, 4,4'-diphenylmethylene dicarboxylic acid , 4, isopropylidene dicarboxylic acid, 1,2-diphenoxyethane-4 ', 4 "-didicarboxylic acid, 2,5-pyridinedicarboxylic acid, benzophenone dicarboxylic acid, etc., It is used alone or in combination of two or more types. The average number of functional groups of the polyol (B1) is preferably 2.0 to 4.0. When the average number of functional groups of the polyol is less than 2.0, the resulting φ foam cannot be highly mechanical. Strength (tensile strength, tear strength, good compression characteristics (low When the average number of functional groups of the polyol exceeds 4.0, the spring constant of the foam obtained is too high, and the performance as a shockproof material cannot be fully exerted. The number average molecular weight of the polyol (B1) It is preferably 1,000 to 1,000 to 3,000. When the number average molecular weight of the polyalcohol is less than 1,000, the obtained spring constant is too high, and it cannot be fully used as a shockproof, buffering b. The polyalcohol When the number average molecular weight exceeds 6,000, the ester-making foam cannot be a foam having high mechanical strength (tensile strength, tear strength, and good compression characteristics (low compression set)), < chain extender (B2) > A chain extender (B2) made of a urethane-forming composition, a chain extender having a number of 2 to 4, and a molecular weight of 600 or less. 4,4-diphenylcarboxylic acid and anthracene can be 2.5 to 3.5 in polyurethane. Polyurethane, cushioning material c 6, 00, the foam strength of the foam material is a functional group -15- 200540196 (12) Here, as the chain extender (B 2), Ethanol, triethylene glycol, propylene glycol, diethylene glycol Low-molecular-weight diols such as diols, 丨, 4-butanediol, neopentyl glycol, low-molecular-weight triols such as glycerol, Sanyuan, Dijing methyl ethyl, hexanetriol, etc. Alcohol, etc. The molecular weight of the chain extender (B2) is less than 600. When the molecular weight of the chain extender exceeds 600, the obtained polyurethane φ cannot have high mechanical strength (tensile strength, tear strength), shrinkage characteristics (low (Compressive permanent deformation) foam < arbitrary component of urethane-forming composition > urethane-forming composition used in the production method of the present invention, terminal prepolymer (A), polyol (B1) and chain Elongating agents (components are required, but components other than these may be contained. Examples of such optional components include catalysts, foam stabilizers (pigments, dyes), antioxidants, and ultraviolet absorbers. The content of water in the urethane-forming composition is preferably less than 0.1, more preferably less than 0.05% by mass. Therefore, by restricting the formation of the urinary bond, as a result, a polyurethane foam having a low spring constant and good compression characteristics (particularly, compression set) for a rail gasket can be manufactured. < Molar ratio of urethane-forming composition ([NC0] / [0H]) The urethane-forming composition used in the production method of the present invention, diethylene glycol, 1,6-hexamethylol propylene glycerol Ester foam and NCO B 2 are necessary, and the mass% of color is suitable for iron. It is small. From the viewpoint of ensuring -16-200540196 (13) good hardenability, isocyanate groups and hydroxyl groups The molar ratio ([NC0] / [0H]) is 0.8 0- 1.20, preferably 0.90-1.10. < Formation of polyurethane foam > The production method of the present invention is characterized by mechanically agitating the urethane-forming composition described above in an inert gas environment to disperse the inert gas in the urinary formation. A foam-like raw material is prepared in the composition, and the raw material is poured into a molding die and hardened to form a polyurethane foam made into a gasket for railroad tracks. Here, the method of preparing a foam-like raw material by dispersing an inert gas in the urethane-forming composition by mechanical stirring as described above is called a mechanical foam foaming method. By adopting the mechanical foaming method, a polyurethane foam having a honeycomb structure having a fine (average honeycomb diameter = 1 to 200 μm) and a small variation in the size of different parts in the same gasket (uniform load distribution) ^ Good track gaskets). Such a fine and uniform honeycomb structure cannot be formed by a conventional manufacturing method using a foaming agent (reactive foaming agent / non-reactive foaming agent). Here, in the step of mechanically foaming the urethane-forming composition, the inert gas is brought into contact with the composition, and mechanical stirring (providing shear force) is performed under normal pressure or a pressure of 0.5 MPa or less. The particles (bubbles) of this inert gas are uniformly dispersed, and a foam-like raw material (unhardened group-17- 200540196 (uncured group-17- 200540196) having a density of 0.3 to 1.0 § / 〇ηι and an average honeycomb diameter of 1 to 200 μm is prepared. ))) It is better to harden the raw material in the molding die. Here, mechanical agitation works well under normal pressure or under a pressure of 0.5 MPa or less. When mechanical stirring is performed under a pressure of more than 0.5 MPa, the pressure generated at the die exit may be suddenly released, and the mixed bubbles (dispersed inert gas) may break. Since the raw material (unhardened composition) produced by mechanical foaming is foamy, it is not necessary to consider the foaming pressure in the mold. Therefore, the molding mold in which the φ is injected into the raw material does not require high strength as the molding mold used in the water foaming system, and a simple molding mold can be used. Therefore, by using such a simple molding die, it is possible to ensure that the shim for a rail can be manufactured with high dimensional accuracy and free from poor molding such as air stagnation. < Polyurethane foam > The density of the polyurethane foam used to make the rail pad for the present invention is 0.3 to 1.0 g / cm3, preferably 0.5 to 0.9 g / cm3. Polyurethane foams with a φ density of less than 0.3 g / cm3 cannot be foams with sufficient mechanical strength. On the other hand, polyurethane foams with a density exceeding 1.0 g / cm3 have too high a spring constant and cannot fully exert their performance as shock-proof and cushioning materials. The average cellular diameter of the polyurethane foam made into the rail gasket is 1 to 200 μm, preferably 5 to 120 μm. Polyurethane foam 'having an average honeycomb diameter of less than 1 µm, like the unfoamed foam, cannot exhibit the properties required of the foam. On the other hand, a polyurethane foam having an average honeycomb diameter exceeding 200 μm cannot be a foam having uniform physical properties. -18- 200540196 (15) Polyurethane foam made of rail gaskets has a honeycomb structure that is fine (average honeycomb diameter = 1 to 200 μm) and has small variations in size at different locations. The performance required by the rail gasket (especially the spring constant) has small deviations at different locations, so the load has good uniform dispersion. The spring constant of the polyurethane foam used as the rail gasket is preferably 3 to 60 MN / m, more preferably 4 to 30 MN / m, and particularly preferably 5 to 15 MN / m. Such a polyurethane foam having too small a spring constant cannot be a foam having sufficient φ mechanical strength. On the other hand, polyurethane foams with too large spring constants cannot fully exhibit their performance as shock-proof and cushioning materials. The polyurethane foam thus produced has excellent shock resistance and cushioning properties, and thus can be used as a shockproof material other than a rail gasket. [Embodiments] Examples φ Hereinafter, examples of the present invention will be described, but the present invention is not limited to these examples. The following ratios are quality benchmarks. < Synthesis Example 1 > According to the formulation shown in Table 1 below, a reaction vessel equipped with a stirrer, a cooling tube, a nitrogen introduction tube, and a thermometer having a capacity of 100 mL was charged with MDI (containing 2, 2 in a proportion of 1% by mass or less). An isomer mixture composed of 2,4 -'- MDI and 2,4'-MDI, which contains 4,4'-MDI diphenylmethane diisocyanate in a proportion of 99% by mass or more) 100.0 parts by mass, and more -19- 200540196 (16 ) Polyol (i) [poly (tetramethylene oxide) polyol having a nominal average number of functional groups = 2, a number average molecular weight = 2,000,000], 166.2 parts by mass, and stirred at 80T for 4 hours to perform a urethane reaction NCO terminal prepolymer (A) having an NCO content of 10.0% by mass (hereinafter referred to as "prepolymer (A-1)") ° < Synthesis Example 2 > According to the formulation shown in Table 1 below, A urethane reaction was performed in the same manner as in Synthesis Example 1 except that the addition amount φ of the polyol (i) was changed to 270.6 parts by mass to obtain an NCO content of 6.0 mass ° /. NCO terminal prepolymer (A) (hereinafter, referred to as "prepolymer (A · 2)"). < Synthesis Example 3 > According to the formulation shown in Table 1 below, except that the amount of the polyol (i) was changed to 56.2 parts by weight, urethane reaction was performed in the same manner as in Synthesis Example 1 to obtain an NCO content. 20.0% by mass of NCO-terminated prepolymer (hereinafter referred to as "prepolymer (a-1),"). ≪ Synthesis Example 4 > According to the formulation of Table 1 below, except for the addition of the polyol (i) Except that the amount was changed to 96.9 parts by mass, a urethane reaction was performed in the same manner as in Synthesis Example 1 to obtain an NCO terminal prepolymer (hereinafter referred to as "prepolymer (a-2)") having an NCO content of 15.0% by mass. < Synthesis Example 5 > -20- 200540196 (17) According to the formula shown in Table 1 below, except for the addition of polyol (Η) [nominal average number of functional groups = 2 'number average molecular weight = 1,000 poly (tetramethyl oxide) (Ene) polyol] 65.8 parts by mass in place of polyol ⑴, the urethane reaction was performed in the same manner as in Synthesis Example 1 to obtain an NC0 content of 17.0 mass. "Prepolymer (a_3) ,,). Table 1 Synthesis example 1 Synthesis example 2 Synthesis example 3 Synthesis example 4 Synthesis example 5 Prepolymer A-1 A-2 a-1 a-2 a-3 MDI 100.0 100.0 100.0 100.0 100.0 Polyol (i) 166.2 270.6 56.2 96.9 Polyol (ii) •-65.8 NCO content [mass%] 10.0 6.0 20.0 15.0 17.0 MDI: an isomer mixture composed of 2,2, -MDI and 2,4'-MDI in a proportion of 1 mass% or less, with 99% by mass or more containing #diphenylmethane diisocyanate with 4,4 '-MDI * polyol (i): poly (tetramethylene oxide) with a nominal average functional group number = 2 and a number average molecular weight = 2,000 ) Polyols * Polyols (ii): Poly (tetramethylene oxide) polyols with a nominal average number of functional groups = 2 and a number average molecular weight = 1,000 < Mixed Example 1 > According to the formula shown in Table 2 below ' After the polyol (1) [poly (tetramethylene oxide-21-200540196 (18)) polyol having a nominal average number of functional groups = 2, a number average molecular weight = 2,00], 7 5 · 4 parts by mass, and Polyol (3) [poly (propylene oxide) polyol having a nominal average number of functional groups = 3 and a number average molecular weight = 3,000] 24.6 parts by mass of 1,4-butanediol 9.3 parts by mass, foam stabilizer (organic fatty acid esters) 0.5 parts by mass, tin-based catalyst (D 0 TD L) 0 · 0 0 2 parts by mass, and mixed to obtain a polyol mixture (hereinafter, referred to as "polyol Mixture (B -1),). Φ < Mixing Example 2 > According to the formulation shown in Table 2 below, the polyol (2) [the nominal average number of functional groups = 2, the number average molecular weight = 1500 of poly ( Tetramethylene oxide) Polyol] 75.4 parts by mass, 24.6 parts by mass with polyol (3), 9.3 parts by mass of 1,4-butanediol, 0.5 parts by mass of foam stabilizer, and 0.002 of tin catalyst The parts by mass are mixed to obtain a polyol mixture (hereinafter referred to as "polyol mixture (B-2)"). ≪ Mixing Example 3 > According to the formulation shown in Table 2 below, the polyol (3) 100 parts by mass, 20.0 parts by mass with 1,4-butanediol, 0.5 parts by mass with a foam stabilizer, and 0.002 parts by mass with a tin-based catalyst to prepare a polyol mixture (hereinafter, referred to as "polyol Mixture (B_3) "). <Comparative Mixing Example 1 > According to the formula shown in Table 2 below, Alcohol (0.01 million parts by mass, 6.0 parts by mass with ethylene glycol), amine-based catalyst (triethylenedi-22-200540196 (19) amine). 8 parts by mass, 0.7 mass by water (reactive foaming agent) Parts were mixed to obtain a polyol mixture (hereinafter, referred to as "polyol mixture (b-1)") < Comparative mixing example 2 > According to the formulation shown in Table 2 below, the polyol (3) 100.0 mass Parts, mixed with 13.5 parts by mass of ethylene glycol, 0.03 parts by mass of a tin-based catalyst, 0.15 parts by mass of an amine-based catalyst, and 0.5 parts by mass of water to prepare a polyol mixture (hereinafter referred to as "polyol mixture (b-2)") .
-23- 200540196 (20) 表2 混合例1 混合例2 混合例3 比較混合例1 比較混合例2 多元醇混合物 B-1 B-2 B-3 b-1 b-2 多元醇（1) 75.4 100.0 多元醇（2) 75.4 多元醇（3) 24.6 24.6 100.0 100.0 1，4-丁二醇 9.3 9.3 20.0 乙二醇 16.0 13.5 整泡劑 (有機脂肪酸酯類） 0.5 0.5 0.5 - - 錫系催化劑 (DOTDL) 0.002 0.002 0.002 0.03 胺系催化劑 (三乙烯二胺） - - - 0.8 0.15 水(反應型發泡劑） - • 0.7 0.5 多元醇（1):公稱平均官能基數=2、數平均分子量 =2，000的聚（氧化四甲烯）多元醇 *多元醇（2):公稱平均官能基數=2、數平均分子量 =1，500的聚（氧化四甲烯）多元醇 *多元醇（3):公稱平均官能基數=3、數平均分子量 =3,000的聚（氧化丙烯）多元醇 *整泡劑：有機脂肪酸酯類 *錫系催化劑（DOTDL):二辛酸二月桂酸酯 *胺系催化劑：三乙烯二胺 -24- 200540196 (21) <實施例1> 在機械泡沫發泡機的混合頭中，把依據下述表3所示 配方將加熱到40°C的預聚體（A-〇與加熱到4〇t的多元 酉学混合物（B -1 ) ’依據則者的異氰酸酯基與後者的經基 的旲耳比（[N C Ο ] / [ Ο Η ])爲1 · 0 5的比例混合成的尿院形 成性組成物，在相對於該組成物6 0體積份以4 〇體積丨分的 φ 比例供給的乾燥空氣的環境下（混合頭內的壓力=0·2-0.3MPa)，機械攪拌1分鐘，使乾燥空氣微分散在該尿烷 形成性組成物中，調製泡沬狀的原料，將該原料在常壓下 注入模具（ 260mmx220mmx30mm)中，密閉後，把該模具 在80°C的烘箱內放置30分鐘，使注入的泡沬狀原料硬化 ’形成製成軌道墊片的聚氨酯發泡體，從模具中取出該發 泡體。 φ 〈實施例2> 依據下述表3所示的配方，把預聚體（a-ι)與多元 醇混合物（B- 1 )組成的尿烷形成性組成物，在相對於該 組成物ό 5體積份以3 5體積份的比例供給的乾燥空氣的環 境下，機械攪拌1分鐘調製泡沬狀的原料，除此以外，其 他與實施例1同樣地製造由聚氨酯發泡體製成的軌道墊片 <實施例3> -25- 200540196 (22) 依據下述表3所示的配方，將預聚體（a -1 )與多元 醇混合物（B-1 )組成的尿烷形成性組成物，在相對於該 組成物7 5體積份以2 5體積份的比例供給的乾燥空氣的環 境下機械攪拌1分鐘調製泡沫狀的原料，除此以外，其他 與實施例1同樣地調製聚氨酯發泡體製成的軌道墊片。 <實施例4> 依據下述表3所示的配方，除了使用多元醇混合物（ B-2 )替代多元醇混合物（B-1 )以外，其他與實施例1同 樣製造由聚氨酯發泡體製成的軌道墊片。 <實施例5> 依據下述表3所示的配方，除了使用預聚體（A-2 ) 替代預聚體（A-1 )、使用多元醇混合物（B-3 )替代多元 醇混合物（B-1 )以外，其他與實施例1同樣地製造由聚 # 氨酯發泡體製成的軌道墊片。 -26- (23) 200540196 表3 實施例1 實施例2 實施例3 實施例4 實施例5 尿 製成 預聚體 __Α-1 Α-1 Α-1 Α-1 Α-2 院 成分 多元醇混合 形 物 Β-1 Β-1 Β-1 Β-2 Β-3 成 製成成分 [NCO] [ΟΗ] 性 的混合比 (莫耳比) 1.05 1.05 1.05 1.05 1.05 組 例 成 尿烷形成性組成物的 物 密度[g/cm3] 1.1 1.1 1.1 1.1 1.1 對模頭內的供給比（體積比） 尿烷形成性組成物 :乾燥空氣 60:40 65:35 75:25 60:40 60:40 泡沬狀原料的密度[g/cm3] 0.61 0.65 0.75 0.71 0.64 泡沬狀原料的平均蜂窩直徑 [μηι] 80〜160 —— 60〜150 50〜140 50〜140 60〜140 <比較例1 > 依據下述表4所示的配方，把加熱到4 0 °C的預聚體（ a-Ι )與加熱到4〇°C的多元醇混合物（b-Ι )，依據前者的 異氰酸酯基與後者的羥基的莫耳比（[NC〇]/[〇H])爲1.05 的比例，使用實驗室混合機，經過在6〇〇〇rpm條件下攪拌 混合1 〇秒鐘調製發泡性的原料，把該原料注入模具（ 180mmxl40mmxl0mm )內，密閉後，把該模具在 7 0 °C的 烘相內放置1小時’使注入的原料發泡、硬化，形成製成 -27- 200540196 (24) 軌道墊片的聚氨酯發泡體，從模具中取出該發泡體。 <比較例2 > 依據下述表4所示的配方，除了使用預聚體（a _ 2 ) 替代預聚體（a-1)以外，其他與比較例1同樣地製造採用水 發泡的聚氨酯發泡體製成的軌道墊片。 〇 <比較例3> 依據下述表4所示的配方，除了使用預聚體（&_3) 替代預聚體（a-1 )、使用多元醇混合物（b-2)替代多元醇 混合物（b-1)、把兩者的混合比例改變成莫耳比（ [NCO]/[〇H])爲1·〇〇的比例以外，其他與比較例1同樣 地製造採用水發泡的聚氨酯發泡體製成的軌道墊片。 表4 比較例1 比較例2 比較例3 發 製成 預聚體 3-1 a- 2 a- 3 iCi 多元醇混合 性 成分 b-1 b-1 b-2 物 的 [NC01 原 製成成分的 [OH] 料 混合比例 (莫耳比） 1.05 1.05 1.00 對實施例1 - 5與比較例1 - 3製得的各軌道墊片，就下 述的專案進行測定、評價。把結果示於T述表5。 -28- 200540196 (25) (1 )密度·· 依據Π S Z 8 8 0 7進行測定， (2 )拉伸強度與伸長率： 依據JIS K 62 5 1製作亞鈴形3號作爲試片，在拉伸速 度=5 0 0 m m /分條件下進行拉伸試驗進行測定。 (3 )耐熱性： 依據：FIS K 625 7，對試片（亞鈴形3號）在70°C賦予 96小時的熱歷程，在室溫下放置1小時後，與上述（2 ) 同樣地進行拉伸試驗，測定相對於老化前的拉伸強度的保 持率。 (4 )壓縮永久變形： 依據 ASTM D 395，在溫度= 70°C、載重=1·5ΚΝ、壓 縮率=50%、壓縮時間=48小時、壓縮後的室溫放置時間 =24小時的條件下進行測定。 (5 )彈簧常數： • 使用壓縮試驗機，對試片（製得的軌道墊片）2次預 壓縮後，施加達到100ΚΝ的載重，測定載重-撓度曲線， 由該曲線的2-3 0ΚΝ間的撓度量算出彈簧常數。 (6)空氣滯留的發生狀況： 目視觀察軌道墊片成型時的上面空氣滯留的有無（程 度），沒有空氣滯留的情況爲「〇」、上面不足25% (面 積比率）有空氣滞留的情況爲「△」、上面的25¼以上（ 面積比率）有空氣滯留的情況爲「X」。 (7 )芯密度差 -29- 200540196 (26) 從軌道墊片厚度方向的上部與下部分別切出試片（ 1 0 0 m m X 3 0 m m X 5 m m )測定密度，測定其密度差。 (8 )排氣孔附近的硬化狀態： 對比較例的軌道墊片，由成型用模具的排氣孔附近的 硬度進行評價。此外，實施例中不需要排氣孔。 (9 )平均蜂窩直徑（平均値）： 測定存在於任意選擇的3個切斷面的蜂窩的直徑，測 定各切斷面上的平均蜂窩直徑（Di、D2、D3)，再求這些 的平均値 D[D= ( Di+Dz + Dsn]。 (1 0 )蜂窩直徑的偏差： 對各實施例的軌道墊片’求相對於以上述（9 )求出 的平均蜂窝直徑（〇l、D2、D3)的平均値D的偏差[(〇-Di) /D、（D-D2) /D、（D-D3) /D 的最大値]’不足 1〇/° 的情況記爲「Ο」、1 以上的情況記爲「△」°-23- 200540196 (20) Table 2 Mixed example 1 Mixed example 2 Mixed example 3 Comparative mixed example 1 Comparative mixed example 2 Polyol mixture B-1 B-2 B-3 b-1 b-2 Polyol (1) 75.4 100.0 Polyol (2) 75.4 Polyol (3) 24.6 24.6 100.0 100.0 1,4-butanediol 9.3 9.3 20.0 Ethylene glycol 16.0 13.5 Foam stabilizer (organic fatty acid esters) 0.5 0.5 0.5--Tin catalyst (DOTDL ) 0.002 0.002 0.002 0.03 Amine-based catalyst (triethylenediamine)---0.8 0.15 Water (reactive foaming agent)-• 0.7 0.5 Polyol (1): Nominal average number of functional groups = 2, number average molecular weight = 2, Poly (tetramethylene oxide) polyol * polyol (2): Poly (tetramethylene oxide) polyol * polyol (3): nominal average functional group number = 2, number average molecular weight = 1,500: nominal Poly (propylene oxide) polyol with an average number of functional groups = 3 and a number-average molecular weight = 3,000 * Foaming agent: organic fatty acid esters * tin-based catalyst (DOTDL): dioctanoic acid dilaurate * amine catalyst: triethylenediene Amine-24- 200540196 (21) < Example 1 > In a mixing head of a mechanical foam foaming machine The prepolymer (A-0 and multivariate chemical mixture (B -1) heated to 40 ° C. according to the formula shown in Table 3 below) was used. The urinary-forming composition formed by mixing the base's ear-to-ear ratio ([NC 〇] / [Ο Η]) at a ratio of 1.05, and 60 vol. Parts of the composition in 40 vol. Under the environment of dry air supplied in φ ratio (pressure in the mixing head = 0 · 2-0.3MPa), mechanical agitation for 1 minute to finely disperse the dry air in the urethane-forming composition to prepare foam-like raw materials The raw material was injected into a mold (260mmx220mmx30mm) under normal pressure. After being sealed, the mold was placed in an oven at 80 ° C for 30 minutes to harden the injected foam-like raw material to form a polyurethane foam made of track gasket. The foam was removed from the mold. Φ <Example 2> A urethane composed of a prepolymer (a-ι) and a polyol mixture (B-1) was prepared according to the formulation shown in Table 3 below. Formable composition in a ring of dry air supplied at a ratio of 35 parts by volume relative to 5 parts by volume of the composition Under the circumstances, mechanically agitating for 1 minute to prepare foam-like raw materials, the track gasket made of polyurethane foam was manufactured in the same manner as in Example 1 < Example 3 > -25- 200540196 (22) According to the formulation shown in Table 3 below, a urethane-forming composition composed of a prepolymer (a -1) and a polyol mixture (B-1) was added in an amount of 2 5 to 75 parts by volume with respect to the composition. A track pad made of a polyurethane foam was prepared in the same manner as in Example 1 except that foamy raw materials were prepared by mechanically stirring for 1 minute in an environment of dry air supplied in a proportion by volume. < Example 4 > A polyurethane foam system was produced in the same manner as in Example 1 except that the polyol mixture (B-2) was used instead of the polyol mixture (B-1) according to the formulation shown in Table 3 below. Into a track gasket. < Example 5 > According to the formulation shown in Table 3 below, except that the prepolymer (A-2) was used in place of the prepolymer (A-1), and the polyol mixture (B-3) was used in place of the polyol mixture ( Except for B-1), a track pad made of poly #urethane foam was produced in the same manner as in Example 1. -26- (23) 200540196 Table 3 Example 1 Example 2 Example 3 Example 4 Example 5 Prepolymer made from urine __Α-1 Α-1 Α-1 Α-1 Α-2 Hospital ingredients polyol Mixed form B-1, B-1, B-1, B-2, and B-3. The composition is [NCO] [〇Η]. The mixing ratio (molar ratio) is 1.05 1.05 1.05 1.05 1.05. Material density [g / cm3] 1.1 1.1 1.1 1.1 1.1 Supply ratio (volume ratio) to the die head Urethane-forming composition: Dry air 60:40 65:35 75:25 60:40 60:40 Bubbles Density of grate-like material [g / cm3] 0.61 0.65 0.75 0.71 0.64 Average honeycomb diameter of foam-like material [μηι] 80 ~ 160 —— 60 ~ 150 50 ~ 140 50 ~ 140 60 ~ 140 < Comparative Example 1 > According to the formulation shown in Table 4 below, the prepolymer (a-1) heated to 40 ° C and the polyol mixture (b-1) heated to 40 ° C, the isocyanate group of the former and the latter The molar ratio ([NC〇] / [〇H]) of the hydroxyl group is 1.05, and it is prepared by using a laboratory mixer and stirring and mixing at 6,000 rpm for 10 seconds. Foamy raw material, the raw material is injected into the mold (180mmxl40mmxl0mm), after sealing, the mold is placed in the baking phase at 70 ° C for 1 hour to make the injected raw material foam and harden to form -27- 200540196 (24) The polyurethane foam of the track gasket, and the foam is taken out of the mold. < Comparative Example 2 > According to the formulation shown in Table 4 below, except that the prepolymer (a_2) was used in place of the prepolymer (a-1), the same procedure as in Comparative Example 1 was used to produce water foaming. Track gasket made of polyurethane foam. 〇 < Comparative Example 3 > According to the formulation shown in Table 4 below, except that the prepolymer (& _3) was used instead of the prepolymer (a-1), and the polyol mixture (b-2) was used instead of the polyol mixture. (B-1) A water-foamed polyurethane was produced in the same manner as in Comparative Example 1 except that the mixing ratio of the two was changed to a ratio of [MCO] ([NCO] / [〇H]) to 1.00. Track gasket made of foam. Table 4 Comparative example 1 Comparative example 2 Comparative example 3 Prepolymer 3-1 a- 2 a- 3 iCi polyol mixed component b-1 b-1 b-2 [NC01 original component [OH] Material mixing ratio (Molar ratio) 1.05 1.05 1.00 For each track gasket prepared in Examples 1 to 5 and Comparative Examples 1 to 3, the following items were measured and evaluated. The results are shown in Table 5 below. -28- 200540196 (25) (1) Density: Measured according to Π SZ 8 8 0 7; (2) Tensile strength and elongation: According to JIS K 62 5 1, a sub-bell shape No. 3 was made as a test piece, The tensile test was performed under the condition of a tensile speed = 500 mm / min. (3) Heat resistance: Basis: FIS K 625 7, the test piece (sub-bell-shaped No. 3) was given a thermal history of 96 hours at 70 ° C, and after being left at room temperature for 1 hour, the same as (2) above A tensile test was performed to measure the retention rate with respect to the tensile strength before aging. (4) Compression permanent deformation: According to ASTM D 395, under the conditions of temperature = 70 ° C, load = 1.5KN, compression ratio = 50%, compression time = 48 hours, and room temperature after compression = 24 hours Perform the measurement. (5) Spring constant: • Using a compression tester, pre-compress the test piece (prepared track pad) twice, and apply a load of 100KN to determine the load-deflection curve. From 2-3 to 0KN of this curve Calculate the spring constant. (6) Occurrence of air stagnation: Visually observe the presence or absence (degree) of air stagnation on the upper surface of the track gasket during molding. If there is no air stagnation, it is "0". If the air stagnation is less than 25% (area ratio), "△", if there is air stagnation above 25¼ (area ratio) above, "X". (7) Core density difference -29- 200540196 (26) Cut the test piece (100m X 30m X 5mm) from the upper and lower parts of the thickness direction of the track pad to measure the density and measure the density difference. (8) Hardened state near the exhaust hole: For the track gasket of the comparative example, the hardness near the exhaust hole of the molding die was evaluated. In addition, an exhaust hole is not required in the embodiment. (9) Average honeycomb diameter (average 値): Measure the diameter of the honeycomb existing in the three cut surfaces arbitrarily selected, measure the average honeycomb diameter (Di, D2, D3) on each cut surface, and then calculate the average of these値 D [D = (Di + Dz + Dsn]. (1 0) Deviation of honeycomb diameter: For the orbital spacers of the examples, the average honeycomb diameter (0l, D2 obtained in (9)) was calculated. , D3) The deviation of the average 値 D [(〇-Di) / D, (D-D2) / D, (D-D3) / D maximum 値] ') Less than 1 / ° is recorded as "0" For cases above 1, 1 is recorded as "△" °
-30- 200540196 (27) 表5 實施 例1 實施 例2 實施 例3 實施 例4 實施 例5 比較 例1 比較 例2 比較 例3 密度 [g/cm3] 0.60 0.64 0.75 0.70 0.63 0.75 0.67 0.75 拉伸強度 [MPa] 3.5 4.1 5.6 4.7 3.3 7.9 7.1 8.0 伸長率 [%] 450 470 490 430 320 250 300 290 耐熱性 [%] 103 100 100 99 100 96 95 90 壓縮永久變形 [%] 10.8 8.1 3.5 4.6 3.5 16 17 36 彈簧常數 [MN/m] 6.5 8.2 14.3 11.8 9.4 19.2 20.8 29.0 空氣滯留的發生狀況 Ο 0 0 0 0 Δ Δ X 芯密度差 [g/cm3] 0.01 0.01 0.01 0.01 0.03 0.08 0.08 0.10 排氣孔附近的硬化狀 態 - - - - - 硬 硬 硬 平均蜂窩直徑 (平均値)[μπι] 116 88 68 74 79 300〜 300〜 300〜 蜂窩直徑的偏差 0 0 0 0 Δ • - 本發明的鐵軌用墊片，適合作爲爲了減輕車輛在鐵車九 的軌式軌道上行駛時産生的振動與噪音而插入鐵軌與枕木 之間的軌道墊片、鋪在枕木下的枕木用墊片、鋪在鈑式軌 道的導軌下的軌道平板用防震材料等使用。 -31 --30- 200540196 (27) Table 5 Example 1 Example 2 Example 3 Example 4 Example 5 Comparative example 1 Comparative example 2 Comparative example 3 Density [g / cm3] 0.60 0.64 0.75 0.70 0.63 0.75 0.67 0.75 Tensile strength [MPa] 3.5 4.1 5.6 4.7 3.3 7.9 7.1 8.0 Elongation [%] 450 470 490 430 320 250 300 290 Heat resistance [%] 103 100 100 99 100 96 95 90 Compression set [%] 10.8 8.1 3.5 4.6 3.5 16 17 36 Spring constant [MN / m] 6.5 8.2 14.3 11.8 9.4 19.2 20.8 29.0 Occurrence of air retention 0 0 0 0 0 Δ Δ X Core density difference [g / cm3] 0.01 0.01 0.01 0.01 0.03 0.08 0.08 0.10 Hardened state-----Hard and hard Average honeycomb diameter (average 値) [μπι] 116 88 68 74 79 300 ~ 300 ~ 300 ~ Deviation of honeycomb diameter 0 0 0 0 Δ •-The gasket for rails of the present invention, It is suitable as a track gasket inserted between the rail and the sleeper to reduce the vibration and noise generated when the vehicle is traveling on the railroad track of the railway car. The lower rail plate is used for shock-proof materials. -31-