JP4253917B2

JP4253917B2 - Adhesive composition and adhesive sheet

Info

Publication number: JP4253917B2
Application number: JP12163999A
Authority: JP
Inventors: 伸一市原; 昭洋山田; 弘介田辺
Original assignee: DIC Corp
Current assignee: DIC Corp
Priority date: 1999-04-28
Filing date: 1999-04-28
Publication date: 2009-04-15
Anticipated expiration: 2019-04-28
Also published as: JP2000313862A

Description

【０００１】
【発明の属する技術分野】
本発明は、天然ゴム、クロロプレンゴム、ＥＰＴ（エチレン−プロピレン−ターポリマー）ゴム等のゴム類や、オレフィン系、スチレン系、塩ビ系、ウレタン系等の熱可塑性エラストマー類からなる成形品を接着するために用いる粘着剤及び粘着シート類に関する。
【０００２】
【従来の技術】
ゴムや熱可塑性エラストマーの成形品（以下ゴム等の成形品）は、自動車用部材、家電、ＯＡ機器用部材の他、各種工業用製品に多く使われている。ところが、ゴム等の成形品は、一般に、各種充填剤、加硫剤、油分、可塑剤等が配合されていたり、成形品を加硫する場合には、プレス金型から容易に型離れさせるためにシリコーンオイル等の離型剤等が成形品の表面に付着しているため、成形品への接着強度が低い。又、ゴム等の成形品をテープ類で曲面に貼り付ける場合などは、成形品の弾性が高いため、接着性の悪さから剥がれ易いという問題があった。
【０００３】
従って、これまでは被着体としてのゴム等の成形品の表面をバフ研磨、溶剤洗浄、プライマー塗工の順で処理し、粘着シート類を貼合せ被着体に貼り付ける方法が取られていた。しかしプライマーや溶剤を使用するため作業環境が悪く、かつ作業工程も複雑であり、バフ研磨のばらつきにより接着性がばらつくといった問題があった。
【０００４】
これらの問題を解決するために、特開平５−７８６３４号公報では、ポリイソブチレン等からなる高分子量ゴム質ポリマーに対し、中分子量の液状ないし半液状のゴムと低分子量の粘着付与剤及び／又は軟化剤を加えるとともに、ゲル分率を１０〜４０％に設定した粘着剤及び粘着シートが、ＥＰＴゴム等にバフ研磨等の処理をしなくとも充分な接着力を発揮すると開示されている。しかし、この粘着シートは、粘着剤配合時のすねり工程や粘着剤を基材上に塗工した後に、高温で長時間の加硫熟成が必要であり、また加硫剤や加硫促進剤に過酸化物系の化合物やチウラム系化合物を使用するため取扱い及び安全上問題が多い。
【０００５】
また、従来、ＳＩＳブロックコポリマーを主体とした粘着剤は、様々な用途で使用されている。しかしながら、ゴム等の成形品が使用される自動車、家電、ＯＡ機器等の各種工業用途では、高温高湿下での保存安定性や使用時の耐久性が必要とされ、このようなＳＩＳブロックコポリマーを主体とした粘着剤では、高温高湿下で使用された場合、劣化が起こり易く安定性や耐久性が悪いという問題があった。
【０００６】
更に、ゴム等の成形品は、一般に、各種充填剤、加硫剤、油分、可塑剤等が配合されており、経時的（特に高温高湿下）にブリード成分による表面の光沢（てかり）や、べとつき感が生じるという問題があった。
【０００７】
【発明が解決しようとする課題】
本発明の課題は、上記事情に鑑み、被着体であるゴム等の成形品に対するバフ研磨工程を省略でき、かつ、粘着剤に対するすねり工程、高温加硫工程が不要で安全上問題のある過酸化物等を含まなくとも、充分な凝集力、接着強度を発揮でき、高温高湿下でも劣化が少ないほか、ゴム等の成形品の経時的な表面光沢を改善する粘着剤及び粘着シート類を提供することにある。
【０００８】
【課題を解決するための手段】
本発明者らは鋭意検討した結果、特定のジブロック量を持つＳＩＳブロックコポリマーと特定の粘着付与樹脂からなる粘着剤が、安全上問題の多い過酸化物等を含まず、すねり工程や高温での長時間加硫の必要がなく、且つ、被着体に対するバフ研磨等の処理を施さなくとも充分な接着強度を発揮でき、高温高湿下での劣化を抑制し得ることを見いだし本発明を完成するに至った。
【０００９】
即ち、本発明の第一の構成は、ＳＩＳブロックコポリマー１００重量部と、粘着付与樹脂６０〜２００重量部を必須成分として含有する粘着剤において、該ＳＩＳブロックコポリマー中のジブロック量が３０〜８０重量％であり、該粘着付与樹脂がＣ５石油系樹脂を含み、且つ、Ｃ５石油樹脂以外の粘着付与樹脂の水酸基価が２５以下であることを特徴とする粘着剤組成物である。
【００１０】
又、本発明の構成は、前記した粘着付与樹脂量の１０〜３０重量％が常温で液状の粘着付与樹脂及び／又は軟化剤であることを特徴とする粘着剤組成物である。
【００１１】
又、本発明の構成は、前記した水酸基価が２５以下である粘着付与樹脂がロジン系樹脂であることを特徴とする粘着剤組成物である。
【００１２】
更に、本発明の第二の構成は、支持体の少なくとも片面に前記した粘着剤を設けたことを特徴とする粘着シート類である。
【００１３】
【発明の実施の形態】
本発明に使用するＳＩＳブロックコポリマーは、ジブロック量が３０〜８０重量％であること以外が特に限定されるものではない。ジブロック量が３０重量％未満では、ゴム等の成形品に対し充分な接着強度が得られない。８０重量％を越えると粘着剤の凝集力が著しく低下する。ＳＩＳブロックコポリマーの分子量は、１万〜８０万の範囲にあることが好ましく、より好ましくは３万〜５０万の範囲にあるのが良い。１万未満では粘着剤の凝集力が著しく低下する。一方、８０万を越えるとゴム等の成形品に対し濡れが減少し充分な接着強度が得られない。
【００１４】
本発明に使用するＣ５石油系樹脂は、一般にナフサの分解で得られるＣ５留分よりイソプレン及びシクロペンタジエンを抽出分離した残りを重合した樹脂であるが、例えば、エスコレッツ１２０２、１３０４、１４０１（トーネックス製）、ウイングタック９５（グッドイヤー製）、クイントンＫ１００、Ｒ１００、Ｆ１００（日本ゼオン製）、ピコタック９５、ピコペール１００（理化ハーキュレス製）等が挙げられる。
【００１５】
本発明に使用するＣ５石油系樹脂以外の粘着付与樹脂としては、テルペン系樹脂、ロジン系樹脂、テルペン−フェノール樹脂、スチレン系樹脂、クマロン−インデン樹脂、キシレン樹脂、フェノール樹脂、Ｃ５以外の石油樹脂（芳香族系、脂環族系等）が挙げられる。好ましくはロジン系樹脂が挙げられる。これらの粘着付与樹脂の水酸基価が２５を超える場合は、高温高湿下で劣化し易くＳＩＳブロックコポリマーの主鎖切断を引き起こすため、接着強度が低下し、耐熱保持力が悪化する。
【００１６】
本発明に使用する粘着付与樹脂の総量が６０重量部未満の場合は、ゴム等の成形品への接着強度が低下し、耐湿劣化後の接着性も低下する。総量が２００重量部を越える場合は、耐熱保持力が低下する。
【００１７】
本発明に使用する液状の粘着付与樹脂及び／又は軟化剤は、例えば、室温で液状の上記粘着付与樹脂や、プロセスオイル、ポリエステル系可塑剤、ポリブテン等の低分子量の液状ゴムが挙げられる。粘着付与樹脂総量に占める液状粘着付与樹脂及び／又は軟化剤の割合は、好ましくは１０〜３０重量％である。１０重量％未満ではゴム等の成形品への濡れ性が悪くなり接着強度が低下するほか、３０重量％を越えると凝集力が悪くなり、耐反発性においても多少浮きが生じる。
【００１８】
本発明においては、他のポリマー成分や、架橋剤が使用出来る。また粘着剤で一般に用いられる各種添加剤、例えば、酸化防止剤、紫外線吸収剤、充填剤、顔料、増粘剤等を、接着強度を低下しない範囲で使用することが出来る。このようにして調整される本発明の合成ゴム系粘着剤は、通常トルエン、ヘキサン等の有機溶剤に希釈され、溶液状で、又は高温で溶融され、ゴム等の成形品の接着用途の粘着剤として使用される。
【００１９】
この粘着剤を直接被着体に塗工しても良いが、一般に支持体の少なくとも片面に設けられ、テープ状、シート状で使用されるが、ゴム等の成形品を被着体に接着するという目的から支持体の両面に粘着剤を設けた両面テープ状にすることが望ましい。通常は剥離紙にいったん上記粘着剤を設け（溶液の場合は塗工後乾燥する）支持体の両面に貼り合わせる。支持体としては特に限定されないが、例えば、不織布、布、紙等の多孔質支持体や、ポリエステルフィルム、ポリエチレンフィルム、ポリプロピレンフィルム、ポリ塩化ビニルフィルム等のプラスチックフィルムが挙げられる。厚さは通常５〜２００μｍ程度のものが使用される。又支持体への密着性を向上するために、コロナ処理やプライマー処理を行ってもよい。
【００２０】
支持体上に設ける粘着剤の厚みは、通常１０〜４００μｍ程度が好ましいが、これに限定されるものではない。又、支持体の片面に上記粘着剤を設けて、他方にアクリル系粘着剤等の異なった粘着剤を設けたディファレンシャルタイプの両面テープ仕様にしてもよい。
【００２１】
【実施例】
以下に本発明の実施例について具体的に記すが、これに限定されるものではない。
【００２２】
（実施例１〜４）
ＳＩＳブロックコポリマー、粘着付与樹脂、液状粘着付与樹脂／軟化剤及び酸化防止剤を表１に掲げる重量割合で配合し、トルエンに溶解して粘着剤溶液を調整した。この溶液をアプリケータを用いて、乾燥後の厚さが６０μｍとなるように、セパレータ上に塗布し、８０℃で３分間乾燥した。次に、上記セパレータ上に形成された粘着剤の層を２つ用意して、これらを厚さ５０μｍの不織布の両面に貼り合わせた後、９０℃、４ｋｇｆ／ｃｍ２の加圧にてラミネートを行い、両面粘着シートを作製した。
【００２３】
（比較例１〜６）
ＳＩＳブロックコポリマー、粘着付与樹脂、液状粘着付与樹脂／軟化剤及び酸化防止剤を表２に掲げる重量割合で配合し、実施例と同様に、粘着剤溶液及び両面粘着シートを作製した。
【００２４】
以上の実施例１〜４及び比較例１〜６で得られた両面接着シートについて、接着力、耐湿熱劣化性、耐反発性、表面光沢及び耐熱保持力の評価を行った。以下、評価結果を表１及び表２に示す。尚、評価は、下記の要領にて行った。
【００２５】
〈接着力〉：ＥＰＴ（エチレン−プロピレン−ターポリマー）ゴム及びクロロプレンゴムに、両面粘着シートを２ｋｇ×１往復の加圧にて貼付し、３０分後に引張速度３００ｍｍ／ｍｉｎにて１８０゜剥離接着力を測定した。
【００２６】
〈耐湿熱劣化性〉：ＥＰＴゴムに、両面粘着シートを２ｋｇ×１往復の加圧にて貼付し、８５℃、８５％ＲＨの環境下にて７日間放置後の接着力の低下を評価した。
◎：耐湿熱劣化後の接着力の低下なし
○：接着力の大幅な低下なし（初期の８０％以上）
×：凝集破壊が起こり、接着力の大幅な低下あり（初期の５０％以下）
【００２７】
〈耐反発性〉：２０ｍｍ幅のＥＰＴゴムを、９０゜に折曲げたアルミ板に両面粘着シートにてエッジ部が１０ｍｍの長さになるように貼付し、８５℃、８５％ＲＨの環境下にて７日間放置後の剥がれ状態を評価した。
◎：剥がれなし
○：浮き有り
×：全面剥がれ
【００２８】
〈表面光沢〉：熱可塑性エラストマーを両面粘着シートにてＪＩＳ−Ｚ０２３７に規定された鋼板に貼付し、８５℃、８５％ＲＨの環境下にて７日放置後の熱可塑性エラストマー表面の光沢を評価した。
○：光沢なし
×：光沢あり
【００２９】
〈耐熱保持力〉：ＪＩＳ−Ｚ０２３７に規定された鋼板に、貼付面積２０ｍｍ幅×２０ｍｍにて両面粘着シートを貼付し、７０℃下にて、荷重５００ｇを掛けた時の落下時間を測定した。
○：１時間以上
×：１時間未満
【００３０】
尚、上記の評価において、被着体のＥＰＴゴム、クロロプレンゴムは、厚さ１ｍｍ、硬度６０゜（クラレ製）のものを使用した。また、熱可塑性エラストマーは、オレフィン系で厚さ１ｍｍのものを使用した。配合及び評価結果を以下の表１、２に示す。
【００３１】
【表１】

【００３２】
【表２】

【００３３】
上記表１、２中の▲１▼〜(10)は以下の通りである。また、粘着付与樹脂の( )は、水酸基価を表す。
▲１▼重量平均分子量２０万、スチレン量１４重量％。
▲２▼重量平均分子量１７万、スチレン量１６重量％
▲３▼重量平均分子量１７万、スチレン量１５重量％
▲４▼Ｃ５石油系樹脂：数平均分子量８８５、軟化点１００℃
▲５▼ロジン変性フェノール：数平均分子量６７０、軟化点１５０℃
▲６▼不均化ロジンエステル：数平均分子量１，０００、軟化点１２５℃
▲７▼重合ロジンエステル：数平均分子量８８０、軟化点１２５℃
▲８▼水添テルペンフェノール：数平均分子量８２０、軟化点１３０℃
▲９▼低分子量ポリブテン（液状）：日本石油社製ＨＶ−１００
(10)ヒンダードフェノール：チバスペシャリティケミカルズ社製イルガノックス１０１０
【００３４】
【発明の効果】
以上のように、特定のジブロック量を持つＳＩＳブロックコポリマーと特定の粘着付与樹脂からなる本発明の粘着剤は、安全上問題の多い過酸化物等を含まず、すねり工程や高温での長時間加硫工程の必要がない粘着剤であり、ゴム等の成形品に対し従来のようなバフ研磨やプライマー等の処理を施さなくとも充分な接着強度を発揮でき、高温高湿下での劣化を抑制し得る。また、ゴム等の成型品の経時的な表面光沢を改善することができる。[0001]
BACKGROUND OF THE INVENTION
The present invention bonds molded products made of rubbers such as natural rubber, chloroprene rubber, EPT (ethylene-propylene-terpolymer) rubber, and thermoplastic elastomers such as olefin, styrene, vinyl chloride, and urethane. The present invention relates to an adhesive and an adhesive sheet used for the purpose.
[0002]
[Prior art]
Rubber and thermoplastic elastomer molded products (hereinafter, molded products such as rubber) are widely used in various industrial products in addition to automobile members, home appliances, and OA equipment members. However, molded products such as rubber are generally mixed with various fillers, vulcanizing agents, oils, plasticizers, etc., or when molded products are vulcanized, they are easily removed from the press mold. In addition, since a release agent such as silicone oil adheres to the surface of the molded product, the adhesive strength to the molded product is low. Further, when a molded product such as rubber is attached to a curved surface with tapes, etc., there is a problem that the molded product is highly elastic and therefore easily peeled off due to poor adhesion.
[0003]
Therefore, until now, a method has been adopted in which the surface of a molded article such as rubber as an adherend is processed in the order of buffing, solvent washing, and primer coating, and adhesive sheets are bonded to the adherend. It was. However, since a primer and a solvent are used, the working environment is poor, the working process is complicated, and the adhesiveness varies due to variations in buffing.
[0004]
In order to solve these problems, Japanese Patent Application Laid-Open No. 5-78634 discloses a high molecular weight rubbery polymer composed of polyisobutylene or the like, a medium molecular weight liquid or semi-liquid rubber, a low molecular weight tackifier and / or It is disclosed that a pressure-sensitive adhesive and a pressure-sensitive adhesive sheet having a gel fraction set to 10 to 40% while adding a softening agent exhibit a sufficient adhesive force even if the EPT rubber or the like is not buffed. However, this pressure-sensitive adhesive sheet requires a vulcanization and aging at a high temperature for a long time after applying a slick process or a pressure-sensitive adhesive on the base material. In addition, since peroxide compounds and thiuram compounds are used, there are many problems in handling and safety.
[0005]
Conventionally, pressure-sensitive adhesives mainly composed of SIS block copolymers have been used in various applications. However, in various industrial applications such as automobiles, home appliances and OA equipment where molded articles such as rubber are used, storage stability under high temperature and high humidity and durability during use are required. Such SIS block copolymers In the case of the pressure sensitive adhesive mainly composed of, when used under high temperature and high humidity, there is a problem that the deterioration is likely to occur and the stability and durability are poor.
[0006]
In addition, molded articles such as rubber are generally blended with various fillers, vulcanizing agents, oils, plasticizers, etc., and surface gloss due to bleed components over time (especially under high temperature and high humidity). There was also a problem that a sticky feeling was generated.
[0007]
[Problems to be solved by the invention]
In view of the above circumstances, the problem of the present invention is that it is possible to omit a buffing process for a molded article such as rubber, which is an adherend, and there is a safety problem because a slipping process and a high-temperature vulcanization process for an adhesive are unnecessary. Adhesives and adhesive sheets that can exhibit sufficient cohesive strength and adhesive strength even if they do not contain peroxides, have little deterioration even under high temperature and high humidity conditions, and improve the surface gloss over time of molded products such as rubber Is to provide.
[0008]
[Means for Solving the Problems]
As a result of intensive studies, the present inventors have found that a pressure-sensitive adhesive composed of a SIS block copolymer having a specific diblock amount and a specific tackifying resin does not contain a peroxide or the like, which has many safety problems, and is a sludge process or a high temperature. The present invention has found that there is no need for vulcanization for a long time, and that sufficient adhesion strength can be exhibited without subjecting the adherend to buffing or the like, and deterioration under high temperature and high humidity can be suppressed. It came to complete.
[0009]
That is, the first configuration of the present invention is a pressure-sensitive adhesive containing 100 parts by weight of a SIS block copolymer and 60 to 200 parts by weight of a tackifier resin as essential components, and the amount of diblock in the SIS block copolymer is 30 to 80. The pressure-sensitive adhesive composition is characterized in that the tackifier resin contains C5 petroleum resin, and the hydroxyl value of the tackifier resin other than C5 petroleum resin is 25 or less.
[0010]
The composition of the present invention is a pressure-sensitive adhesive composition characterized in that 10 to 30% by weight of the amount of the above-mentioned tackifying resin is a liquid tackifying resin and / or a softening agent at room temperature.
[0011]
The constitution of the present invention is the pressure-sensitive adhesive composition, wherein the tackifying resin having a hydroxyl value of 25 or less is a rosin resin.
[0012]
Furthermore, the second configuration of the present invention is a pressure-sensitive adhesive sheet characterized in that the pressure-sensitive adhesive described above is provided on at least one surface of the support.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
The SIS block copolymer used in the present invention is not particularly limited except that the diblock amount is 30 to 80% by weight. If the diblock amount is less than 30% by weight, sufficient adhesive strength cannot be obtained for molded products such as rubber. If it exceeds 80% by weight, the cohesive strength of the pressure-sensitive adhesive is remarkably reduced. The molecular weight of the SIS block copolymer is preferably in the range of 10,000 to 800,000, and more preferably in the range of 30,000 to 500,000. If it is less than 10,000, the cohesive force of the pressure-sensitive adhesive is remarkably reduced. On the other hand, if it exceeds 800,000, wetting with respect to a molded product such as rubber is reduced and sufficient adhesive strength cannot be obtained.
[0014]
The C5 petroleum-based resin used in the present invention is a resin obtained by polymerizing the residue obtained by extracting and separating isoprene and cyclopentadiene from a C5 fraction generally obtained by naphtha decomposition. ), Wing tack 95 (manufactured by Goodyear), quinton K100, R100, F100 (manufactured by Zeon Corporation), pico tack 95, picopale 100 (manufactured by Rika Hercules), and the like.
[0015]
Examples of tackifying resins other than C5 petroleum resins used in the present invention include terpene resins, rosin resins, terpene-phenol resins, styrene resins, coumarone-indene resins, xylene resins, phenol resins, and petroleum resins other than C5. (Aromatic, alicyclic, etc.). A rosin resin is preferable. When the hydroxyl value of these tackifying resins exceeds 25, the SIS block copolymer is likely to deteriorate under high temperature and high humidity, so that the main chain of the SIS block copolymer is broken, so that the adhesive strength is lowered and the heat resistant holding force is deteriorated.
[0016]
When the total amount of tackifying resin used in the present invention is less than 60 parts by weight, the adhesive strength to a molded article such as rubber is lowered, and the adhesiveness after moisture resistance deterioration is also lowered. When the total amount exceeds 200 parts by weight, the heat resistant holding force is reduced.
[0017]
Examples of the liquid tackifier resin and / or softener used in the present invention include the above-described tackifier resin that is liquid at room temperature, and low-molecular weight liquid rubber such as process oil, polyester plasticizer, and polybutene. The ratio of the liquid tackifying resin and / or softening agent in the total amount of the tackifying resin is preferably 10 to 30% by weight. If it is less than 10% by weight, the wettability to a molded article such as rubber is deteriorated and the adhesive strength is lowered, and if it exceeds 30% by weight, the cohesive force is deteriorated and the rebound resistance is somewhat lifted.
[0018]
In the present invention, other polymer components and crosslinking agents can be used. Further, various additives generally used in pressure-sensitive adhesives, such as antioxidants, ultraviolet absorbers, fillers, pigments, thickeners, and the like, can be used as long as the adhesive strength is not lowered. The synthetic rubber-based pressure-sensitive adhesive of the present invention prepared in this manner is usually diluted with an organic solvent such as toluene and hexane, melted in a solution or at a high temperature, and used for bonding molded products such as rubber. Used as.
[0019]
This pressure-sensitive adhesive may be applied directly to the adherend, but generally it is provided on at least one side of the support and is used in the form of a tape or sheet, but a molded article such as rubber is adhered to the adherend. For this purpose, it is desirable to form a double-sided tape in which an adhesive is provided on both sides of the support. Usually, the pressure-sensitive adhesive is once provided on release paper (in the case of a solution, it is dried after coating) and is bonded to both surfaces of the support. Although it does not specifically limit as a support body, For example, plastic films, such as porous supports, such as a nonwoven fabric, cloth, paper, a polyester film, a polyethylene film, a polypropylene film, a polyvinyl chloride film, are mentioned. A thickness of about 5 to 200 μm is usually used. In order to improve the adhesion to the support, corona treatment or primer treatment may be performed.
[0020]
The thickness of the pressure-sensitive adhesive provided on the support is usually preferably about 10 to 400 μm, but is not limited thereto. Alternatively, a differential type double-sided tape specification in which the above-mentioned pressure-sensitive adhesive is provided on one side of the support and a different pressure-sensitive adhesive such as an acrylic pressure-sensitive adhesive is provided on the other side may be used.
[0021]
【Example】
Although the Example of this invention is described concretely below, it is not limited to this.
[0022]
(Examples 1-4)
SIS block copolymer, tackifying resin, liquid tackifying resin / softener and antioxidant were blended in the weight ratios listed in Table 1 and dissolved in toluene to prepare a pressure-sensitive adhesive solution. This solution was applied on a separator using an applicator so that the thickness after drying was 60 μm, and dried at 80 ° C. for 3 minutes. Next, after preparing two layers of the pressure-sensitive adhesive formed on the separator and pasting them on both sides of a 50 μm-thick nonwoven fabric, lamination is performed at 90 ° C. and a pressure of 4 kgf / cm 2. A double-sided PSA sheet was prepared.
[0023]
(Comparative Examples 1-6)
SIS block copolymer, tackifying resin, liquid tackifying resin / softener and antioxidant were blended in the weight ratios listed in Table 2, and a pressure-sensitive adhesive solution and a double-sided pressure-sensitive adhesive sheet were prepared in the same manner as in the Examples.
[0024]
The double-sided adhesive sheets obtained in Examples 1 to 4 and Comparative Examples 1 to 6 were evaluated for adhesive strength, resistance to moist heat resistance, resilience, surface gloss, and heat resistance. The evaluation results are shown in Tables 1 and 2 below. The evaluation was performed as follows.
[0025]
<Adhesive strength>: A double-sided PSA sheet was affixed to EPT (ethylene-propylene-terpolymer) rubber and chloroprene rubber with a pressure of 2 kg × 1 reciprocating, and after 30 minutes, 180 ° peel adhesion at a tensile speed of 300 mm / min. The force was measured.
[0026]
<Heat and heat resistance>: A double-sided pressure-sensitive adhesive sheet was applied to EPT rubber with 2 kg × 1 reciprocating pressure, and the decrease in adhesive strength after 7 days in an environment of 85 ° C. and 85% RH was evaluated. .
◎: No decrease in adhesive strength after heat and humidity resistance deterioration ○: No significant decrease in adhesive strength (over 80% of initial)
X: Cohesive failure occurred and there was a significant decrease in adhesion (50% or less of the initial value)
[0027]
<Repulsion resistance>: EPT rubber with a width of 20 mm is attached to an aluminum plate bent at 90 ° with a double-sided adhesive sheet so that the edge is 10 mm long, and the environment is 85 ° C. and 85% RH. The peeled state after standing for 7 days was evaluated.
◎: No peeling ○: Floating ×: Full peeling
<Surface gloss>: A thermoplastic elastomer is attached to a steel sheet specified in JIS-Z0237 with a double-sided PSA sheet, and the gloss of the surface of the thermoplastic elastomer after standing for 7 days in an environment of 85 ° C. and 85% RH is evaluated. did.
○: No gloss x: Glossy [0029]
<Heat resistant holding force>: A double-sided PSA sheet was pasted on a steel sheet specified in JIS-Z0237 with a pasting area of 20 mm width × 20 mm, and the drop time when a load of 500 g was applied at 70 ° C. was measured.
○: More than 1 hour × less than 1 hour [0030]
In the above evaluation, the EPT rubber and chloroprene rubber to be adhered were those having a thickness of 1 mm and a hardness of 60 ° (manufactured by Kuraray). The thermoplastic elastomer used was an olefin-based one having a thickness of 1 mm. The blending and evaluation results are shown in Tables 1 and 2 below.
[0031]
[Table 1]

[0032]
[Table 2]

[0033]
In the above Tables 1 and 2, (1) to (10) are as follows. Further, () in the tackifier resin represents a hydroxyl value.
(1) Weight average molecular weight 200,000, styrene content 14% by weight.
(2) Weight average molecular weight 170,000, styrene content 16% by weight
(3) Weight average molecular weight 170,000, styrene content 15% by weight
(4) C5 petroleum resin: number average molecular weight 885, softening point 100 ° C.
(5) Rosin-modified phenol: Number average molecular weight 670, softening point 150 ° C.
(6) Disproportionated rosin ester: number average molecular weight 1,000, softening point 125 ° C.
(7) Polymerized rosin ester: number average molecular weight 880, softening point 125 ° C.
(8) Hydrogenated terpene phenol: number average molecular weight 820, softening point 130 ° C
(9) Low molecular weight polybutene (liquid): HV-100 manufactured by Nippon Oil Corporation
(10) Hindered phenol: Irganox 1010 manufactured by Ciba Specialty Chemicals
[0034]
【The invention's effect】
As described above, the pressure-sensitive adhesive of the present invention consisting of a SIS block copolymer having a specific diblock amount and a specific tackifying resin does not contain peroxides or the like which are often problematic in safety, and is used in a sludge process or at a high temperature. It is a pressure-sensitive adhesive that does not require a long-term vulcanization process, and can exhibit sufficient adhesive strength without being subjected to conventional buffing or primer treatment for molded products such as rubber. Deterioration can be suppressed. Further, the surface gloss over time of a molded product such as rubber can be improved.

Claims

In the pressure-sensitive adhesive containing 100 parts by weight of SIS block copolymer and 60 to 200 parts by weight of tackifying resin as essential components, the amount of diblock in the SIS block copolymer is 30 to 80% by weight, and the tackifying resin is C5 A pressure-sensitive adhesive composition comprising a rosin resin containing a petroleum petroleum resin and having a hydroxyl value of 25 or less .

The pressure-sensitive adhesive composition according to claim 1, wherein 10 to 30% by weight of the amount of the tackifying resin is a tackifying resin and / or a softening agent that is liquid at room temperature.

A pressure-sensitive adhesive sheet, wherein the pressure-sensitive adhesive according to claim 1 or 2 is provided on at least one side of a support.