A. 黏著帶之整體構成
圖1係本發明之一個實施形態之黏著帶之概略剖視圖。該黏著帶100具備基材10及配置於基材10之至少一個面(圖示例中為單面)之黏著劑層20。
本發明之黏著帶所具備之黏著劑層包含熱膨脹性微球。該熱膨脹性微球可於特定溫度下膨脹。包含此種熱膨脹性微球之黏著劑層藉由利用加熱使熱膨脹性微球發生膨脹，而於黏著面(即黏著劑層表面)產生凹凸，使黏著力下降或消失。於將本發明之黏著帶例如於電子零件(例如陶瓷電容器)之加工時作為加工物之臨時固定用片材使用時，於對該加工物實施特定之加工時表現出臨時固定所需之黏著性，於加工後將黏著帶從加工物剝離時，黏著力藉由加熱而下降或消失，表現出良好之剝離性。於一個實施形態中，熱膨脹性微球包含殼及該殼內所包含之有機溶劑，藉由該有機溶劑之揮發而發生膨脹。
本發明之黏著帶中，對該黏著帶於熱機械分析中以加熱速度3℃/分鐘進行加熱時，從變形開始點至膨脹而變形時之變形量成為最大變形量之一半之時間點之時間為45秒～200秒。更詳細而言，使用圖2進行說明。圖2係表示將本發明之一個實施形態之黏著帶供於熱機械分析時之測定結果之一例之圖，表示該分析中之溫度與黏著帶變形量(位移量)之關係。
對黏著帶進行加溫(加熱速度：3℃/分鐘)，於達到特定之溫度時，黏著帶開始發生變形(膨脹)。該時間點為上述「變形開始點」。為了方便起見，將該變形開始點設為A點。再者，黏著帶之變形主要取決於黏著劑層所包含之熱膨脹性微球之膨脹、收縮。
經過A點後，若繼續加熱，則黏著帶(實質上為熱膨脹性微球)繼續膨脹，之後，開始收縮。例如，於使用包含殼及該殼內所包含之有機溶劑之熱膨脹性微球之情形時，該熱膨脹性微球至特定溫度前係藉由有機溶劑之揮發而膨脹，於有機溶劑全部揮發之時間點開始收縮。開始收縮之點係膨脹而黏著帶之變形量成為最大之點。為了方便起見，將該點設為C點。
進而，將從A點達到C點之間，變形量成為C點之變形量X(圖示例中為100 μm)之一半之點(膨脹而變形時之變形量成為最大變形量之一半之時間點，圖示例中為50 μm)設為B點。
本發明中，從A點達到B點之時間為45秒～200秒。
再者，上述熱機械分析中之分析條件如下所述。
＜分析條件＞
裝置名：Seiko Instruments Inc.公司製造、商品名「TMA/SS150」
測定模式：膨脹法，將黏著劑層設為探針側
試樣尺寸：5 mm見方
探針：1 mm
探針荷重：0 N
測定溫度範圍：室溫(25℃±5℃)～250℃
加溫速度：3℃/分鐘
本發明中，藉由將從A點達到B點之時間設為45秒～200秒，能夠獲得將被黏著體剝離時之糊劑殘留較少之黏著帶。認為從A點達到B點，伴隨著熱膨脹性微球之膨脹，黏著劑層發生變形(膨脹)，但於黏著劑層表面未形成凹凸，或即便形成亦微小，黏著劑層表面之幾乎整面處於被壓抵至被黏著體之狀態。認為此種狀態係與由加熱引起之黏著劑之軟化一同促進對被黏著體之糊劑殘留之狀態。本發明中，藉由將處於此種狀態之時間(即從A點達到B點之時間)設為200秒以下，能夠獲得糊劑殘留較少之黏著帶。另一方面，於從A點達到B點之時間未達45秒之情形時，意味著熱膨脹性微球急遽膨脹。於此種情形時，伴隨著熱膨脹性微球之急遽之變化，有產生被黏著體飛起等不良情況之虞。
從A點達到B點之時間較佳為70秒～180秒，更佳為90秒～170秒。若為此種範圍，則上述效果變得顯著。
從B點達到C點之時間較佳為30秒以上，更佳為60秒以上，進而較佳為180秒以上，尤佳為200秒以上。於經過B點後接近C點之階段，熱膨脹性微球進一步膨脹，伴隨於此，於黏著劑層表面產生凹凸，黏著劑層與被黏著體之接觸面慢慢地變小。其結果，黏著帶之黏著力下降或消失。另一方面，若經過C點而熱膨脹性微球開始收縮，則黏著劑層與被黏著體之接觸面開始增加，黏著帶再次表現出黏著性。即，從B點達到C點前，黏著帶顯示出優異之剝離性。藉由將為該狀態之時間如上所述設為特定時間以上，於將黏著帶用於電子零件等之製造步驟時，能夠充分地確保被黏著體之剝離步驟所花費之時間。又，於從B點達到C點之時間過短之情形時，意味著熱膨脹性微球急遽地變形，有無法追隨熱膨脹性微球之急遽之變形之黏著劑層成分(例如黏著劑)發生小片分離，而小片分離之黏著劑層成分導致糊劑殘留之虞。
從B點達到C點之時間之上限例如為3600秒以下，較佳為1800秒以下，更佳為1000秒以下。若為此種範圍，則可使用內包之有機溶劑量適當之熱膨脹性微球。
於上述熱機械分析中，A點時之溫度(亦稱為A點溫度)較佳為30℃～200℃，更佳為40℃～180℃，尤佳為60℃～180℃。
於上述熱機械分析中，B點時之溫度(亦稱為B點溫度)較佳為50℃～250℃，更佳為70℃～200℃，進而較佳為80℃～150℃。藉由將B點溫度設為50℃以上，能夠防止黏著帶之不需要之剝離性表現(例如夏季等外界氣溫較高之狀況下之剝離性表現)。又，於B點溫度超過250℃之情形時，有於表現出剝離性之前之期間產生黏著帶之劣化、起火等之虞。
於上述熱機械分析中，C點時之溫度(亦稱為C點溫度)較佳為90℃～350℃，更佳為100℃～200℃。
於25℃之環境溫度下，熱膨脹性微球發泡前之將本發明之黏著帶之黏著面貼合於聚對苯二甲酸乙二酯膜(例如厚度25 μm)時之黏著力較佳為0.2 N/20 mm以上，更佳為0.2 N/20 mm～20 N/20 mm，進而較佳為2 N/20 mm～10 N/20 mm。若為此種範圍，則例如能夠獲得作為電子零件之製造中使用之臨時固定用片材而有用之黏著帶。本說明書中黏著力係指藉由依據JIS Z 0237：2000之方法(貼合條件：2 kg輥往返1次、剝離速度：300 mm/min、剝離角度180°)測定之黏著力。
本發明之黏著帶之厚度較佳為30 μm～500 μm，更佳為40 μm～300 μm。B. 黏著劑層
上述黏著劑層包含熱膨脹性微球。於實用上，黏著劑層進而包含黏著劑。
B-1.熱膨脹性微球
作為上述熱膨脹性微球，只要為能夠藉由加熱而膨脹至使黏著劑層表面產生凹凸之程度之微球，則可使用任意適當之熱膨脹性微球。作為上述熱膨脹性微球，例如可使用包含殼及該殼內所包含之揮發性物質(代表性而言為有機溶劑)之微球。
作為形成上述殼之材料，例如可列舉樹脂、玻璃、金屬等。其中較佳為樹脂。若使用樹脂，則可獲得容易藉由加熱而軟化並膨脹之熱膨脹性微球。又，由樹脂形成之殼由於具有與黏著劑之密度接近之密度，故而就容易以較高之均勻性分散於黏著劑層中之方面而言亦有利。
作為形成上述殼之樹脂，例如可使用具有源自能夠進行自由基聚合之單體之結構單元的樹脂。作為該單體，例如可列舉丙烯腈、甲基丙烯腈、α-氯丙烯腈、α-乙氧基丙烯腈、反丁烯二腈等腈單體；丙烯酸、甲基丙烯酸、伊康酸、順丁烯二酸、反丁烯二酸、檸康酸等羧酸單體；偏二氯乙烯；乙酸乙烯酯；(甲基)丙烯酸甲酯、(甲基)丙烯酸乙酯、(甲基)丙烯酸正丁酯、(甲基)丙烯酸異丁酯、(甲基)丙烯酸第三丁酯、(甲基)丙烯酸異𦯉酯、(甲基)丙烯酸環己酯、(甲基)丙烯酸苄酯、丙烯酸β-羧基乙酯等(甲基)丙烯酸酯；苯乙烯、α-甲基苯乙烯、氯苯乙烯等苯乙烯單體；丙烯醯胺、取代丙烯醯胺、甲基丙烯醯胺、取代甲基丙烯醯胺等醯胺單體等。包含該等單體之聚合物可為均聚物，亦可為共聚物。
又，形成上述殼之樹脂亦可為交聯體。藉由交聯，可調整聚合物之排斥自由體積，藉此，能夠控制內包之揮發性物質之擴散性、殼之膨脹性等。該交聯體可進而包含源自分子內具有2個以上之聚合性雙鍵之單體之結構單元。於一個實施形態中，將上述能夠進行自由基聚合之單體與分子內具有2個以上之聚合性雙鍵之單體組合使用。作為分子內具有2個以上之聚合性雙鍵之單體，例如可列舉二乙烯基苯、二乙烯基萘等芳香族二乙烯基化合物；甲基丙烯酸烯丙酯、三丙烯醯基縮甲醛、異氰酸三烯丙酯、乙二醇二(甲基)丙烯酸酯、二乙二醇二(甲基)丙烯酸酯、三乙二醇二(甲基)丙烯酸酯、1,4-丁二醇二(甲基)丙烯酸酯、1,9-壬二醇二(甲基)丙烯酸酯、1,10-癸二醇二(甲基)丙烯酸酯、PEG#200二(甲基)丙烯酸酯、PEG#400二(甲基)丙烯酸酯、PEG#600二(甲基)丙烯酸酯、新戊二醇二(甲基)丙烯酸酯、1,6-己二醇二(甲基)丙烯酸酯、三羥甲基丙烷三(甲基)丙烯酸酯、EO改性三羥甲基丙烷三(甲基)丙烯酸酯、甘油二(甲基)丙烯酸酯、二羥甲基-三環癸烷二(甲基)丙烯酸酯、季戊四醇三(甲基)丙烯酸酯、季戊四醇四(甲基)丙烯酸酯、二季戊四醇六(甲基)丙烯酸酯、新戊二醇丙烯酸苯甲酸酯、三羥甲基丙烷丙烯酸苯甲酸酯、(甲基)丙烯酸2-羥基-3-丙烯醯氧基丙酯、羥基新戊酸新戊二醇二(甲基)丙烯酸酯、二-三羥甲基丙烷四(甲基)丙烯酸酯、2-丁基-2-乙基-1,3-丙二醇二(甲基)丙烯酸酯、聚四亞甲基二醇二(甲基)丙烯酸酯、苯基縮水甘油醚丙烯酸酯六亞甲基二異氰酸酯胺基甲酸酯預聚物、苯基縮水甘油醚丙烯酸酯甲苯二異氰酸酯胺基甲酸酯預聚物、季戊四醇三丙烯酸酯六亞甲基二異氰酸酯胺基甲酸酯預聚物、季戊四醇三丙烯酸酯甲苯二異氰酸酯胺基甲酸酯預聚物、季戊四醇三丙烯酸酯異佛爾酮二異氰酸酯胺基甲酸酯預聚物等。
於一個實施形態中，形成殼之樹脂包含選自由源自丙烯酸異𦯉酯之結構單元、源自甲基丙烯腈之結構單元、源自丙烯腈之結構單元、源自(甲基)丙烯酸甲酯之結構單元、源自偏二氯乙烯之結構單元、及源自(甲基)丙烯酸之結構單元所組成之群中之至少一種。若使用具有該等結構單元之樹脂，則能夠形成對內包之有機溶劑之溶解性較低，於加熱前該有機溶劑難以透過或浸潤之殼。又，若使用上述樹脂，則能夠獲得由加熱引起之變形性良好之熱膨脹性微球。進而，若使用上述單體，則能夠藉由交聯等容易地控制殼之熱性質。
於一個實施形態中，就提高對內包之有機溶劑之耐受性之觀點而言，較佳為使用甲基丙烯腈及/或丙烯腈。於使用該等單體之情形時，源自甲基丙烯腈之結構單元及源自丙烯腈之結構單元之合計含有比率相對於形成殼之樹脂100重量%較佳為10重量%～99重量%，更佳為20重量%～99重量%，尤佳為30重量%～95重量%。若為此種範圍，則能夠獲得溶劑耐受性優異，並且容易適當地設定B點溫度之熱膨脹性微球。
於一個實施形態中，就殼硬度之控制之容易性之觀點而言，較佳為使用(甲基)丙烯酸甲酯。若使用(甲基)丙烯酸甲酯，則能夠例如與交聯性單體(例如上述分子內具有2個以上之聚合性雙鍵之單體)組合並藉由電子束交聯等交聯而容易地控制殼之硬度。於使用(甲基)丙烯酸甲酯之情形時，該(甲基)丙烯酸甲酯之含有比率相對於形成殼之樹脂100重量%較佳為未達65重量%，更佳為1重量%～55重量%，尤佳為1重量%～50重量%。
又，於對殼賦予柔軟性之情形時，較佳為使用偏二氯乙烯。偏二氯乙烯之使用量可根據所需之樹脂之玻璃轉移溫度而設為任意適當之量。
上述殼之厚度較佳為15 μm以下，更佳為7 μm以下，進而較佳為5 μm以下，尤佳為4 μm以下。若為此種範圍，則能夠縮短上述從A點達到B點之時間，容易如上所述將從A點達到B點之時間設為200秒以下。又，上述殼之厚度之下限較佳為1 μm以上，更佳為2 μm以上。若為此種範圍，則能夠製成不易因意外之外力等而被破壞之熱膨脹性微球。又，於殼之厚度未達1 μm之情形時，有因內包於殼中之有機溶劑之濕潤(擴散)而殼之物性發生變化，其結果，從B點達到C點之時間顯著變短之虞。即，藉由將殼之厚度之上下限設為上述範圍，能夠容易地獲得於加熱初期(A點～B點)可迅速地膨脹，於之後之加熱(B點～C點)中可長時間維持膨脹狀態之熱膨脹性微球。進而，藉由將殼之厚度之上下限設為上述範圍，能夠降低發泡時之溫度之不均。
構成上述殼之樹脂之玻璃轉移溫度(Tg)較佳為50℃～250℃，更佳為60℃～200℃，進而較佳為80℃～150℃。若為此種範圍，則能夠獲得可適當地膨脹之熱膨脹性微球，若使用該熱膨脹性微球，則能夠容易地獲得B點溫度經適當地設定之黏著帶。再者，本說明書中，於樹脂為共聚物(copolymer)之情形時，上述玻璃轉移溫度係藉由Fox之計算式而求出。Fox之計算式如下所示，係共聚物之玻璃轉移溫度Tg(℃)與使構成共聚物之單體(monomer)各自均聚而成之均聚物(homopolymer)之玻璃轉移溫度Tgi
(℃)之關係式。再者，於以下之Fox之式中，Tg(℃)表示共聚物之玻璃轉移溫度，Wi
表示單體i之重量分率，Tgi
(℃)表示由單體i形成之均聚物之玻璃轉移溫度。
1/(273＋Tg)＝Σ(Wi
/(273＋Tgi
))
作為由單體形成之均聚物之玻璃轉移溫度，丙烯腈均聚物(AN)：97℃、甲基丙烯酸甲酯均聚物(MMA)：102℃、甲基丙烯腈均聚物(MAN)：120℃、偏二氯乙烯均聚物：75℃、丙烯酸異𦯉酯均聚物：97℃。又，作為該等以外之均聚物之玻璃轉移溫度，可使用「聚合物手冊(Polymer Handbook)」(第4版、John Wiley & Sons, Inc、1999年)中記載之值。再者，於該文獻中，記載有複數個Tg之值之情形時，採用「慣用(conventional)」之值。
形成上述殼之樹脂之玻璃轉移溫度(Tg)與所需之B點溫度之差之絕對值(|Tg－B點溫度|)較佳為45℃以下，更佳為5℃～35℃。若使用具有此種玻璃轉移溫度之樹脂，則變得容易將B點之溫度設為所需之溫度。
上述殼內所包含之揮發性物質代表性為有機溶劑。作為該有機溶劑，例如可列舉碳數為3至8之直鏈狀之脂肪族烴及其氟化物、碳數為3至8之支鏈狀之脂肪族烴及其氟化物、碳數為3至8之直鏈狀之脂環族烴及其氟化物、具有碳數為2至8之烴基之醚化合物、或該烴基之氫原子之一部分被氟原子取代之化合物等。於一個實施形態中，作為有機溶劑，使用丙烷、環丙烷、丁烷、環丁烷、異丁烷、戊烷、環戊烷、新戊烷、異戊烷、己烷、環己烷、2-甲基戊烷、2,2-二甲基丁烷、庚烷、環庚烷、辛烷、環辛烷、甲基庚烷類、三甲基戊烷類等僅由氫原子及碳原子構成之烴類；C3
F7
OCH3
、C4
F9
OCH3
、C4
F9
OC2
H5
等氫氟醚類等。該等有機溶劑可僅使用1種，亦可將2種以上組合使用。上述有機溶劑具有與形成殼之樹脂及/或黏著劑之親和性低、難以溶解殼及/或黏著劑、不易使熱性質等物性發生變化之優點。又，僅由氫原子及碳原子構成之烴類就工業利用之觀點而言較佳。
於一個實施形態中，作為僅由氫原子及碳原子構成之烴類，使用支鏈狀之烴類(例如異丁烷、異戊烷等)。支鏈狀之烴類不易帶電，若使用該溶劑，則能夠防止因帶電而引起之起火等事故。
上述有機溶劑之沸點較佳為-50℃～100℃，更佳為-20℃～100℃。若為此種範圍，則能夠獲得殼可良好地膨脹而不會破壞之熱膨脹性微球。再者，於有機溶劑之沸點過低之情形時，有用於抑制熱膨脹微球製造時之揮發之操作變得繁雜之虞。
上述有機溶劑之沸點(bp)與構成上述殼之樹脂之玻璃轉移溫度(Tg)之差之絕對值(|bp－Tg|)較佳為0℃～150℃，更佳為超過0℃且為150℃以下，進而較佳為5℃～125℃。再者，於使用2種以上之有機溶劑(混合溶劑)之情形時，較佳為重量比率最大之溶劑之沸點與構成上述殼之樹脂之玻璃轉移溫度(Tg)之差為上述範圍。若為此種範圍，則能夠適當且容易地調整從A點達到B點之時間、及從B點達到C點之時間。上述有機溶劑之沸點(bp)較佳為低於形成上述殼之樹脂之玻璃轉移溫度(Tg)。若使用沸點高於殼之玻璃轉移溫度之有機溶劑，則有因對有機溶劑加熱時產生之壓力而破壞殼、或者進而黏著劑飛散等而阻礙對本案發明期待之功能或效果之虞。
又，熱膨脹性微球多數情況下暴露於周圍存在之黏著劑或貼附作業等會在加熱前將熱膨脹性微球壓碎之環境中。因而較佳為於加熱前亦具有蒸氣壓以使熱膨脹性微球不被壓碎。
上述有機溶劑之含有比率相對於熱膨脹性微球之加熱前重量較佳為5重量%～35重量%，更佳為10重量%～30重量%。若為此種範圍，則能夠獲得熱膨脹性微球於黏著劑層中以較高之均勻性分散之黏著帶。於含有比率未達5重量%之情形時，有出於密度較低等原因，於黏著劑層製造中熱膨脹微球容易偏集存在於黏著劑層表面，於加熱後在黏著劑層表面產生過大之凹凸之虞。於含有比率超過35重量%之情形時，有密度較高而於黏著劑層內沈降，即便加熱亦無法於黏著劑層表面形成充分之凹凸而無法獲得所需之剝離性之虞，又，亦有產生糊劑殘留之虞。
於25℃之環境溫度下，使上述熱膨脹性微球發泡前之該熱膨脹性微球之平均粒徑(數量基準)較佳為1 μm～40 μm，更佳為5 μm～40 μm，進而較佳為10 μm～40 μm。若為此種範圍，則能夠獲得於黏著劑層中之分散性較高之熱膨脹性微球。以分散性較高之狀態包含熱膨脹性微球之黏著劑層藉由加熱而產生之凹凸之均勻性較高，可表現出優異之剝離性。上述熱膨脹性微球之平均粒徑例如可藉由聚合該熱膨脹性微球時之條件而控制(詳細情況後述)。再者，本說明書中，平均粒徑可藉由使用光學顯微鏡或電子顯微鏡觀察所使用之熱膨脹性微球、或從加熱前之黏著劑層取出之熱膨脹性微球而進行測定。又，平均粒徑可藉由雷射散射法中之粒度分佈測定法而測定。更具體而言，平均粒徑可使所使用之熱膨脹性微球分散至特定之溶劑(例如水)中後，使用粒度分佈測定裝置(例如島津製作所製造之商品名「SALD-2000J」)進行測定。
於一個實施形態中，熱膨脹性微球之含有比率以由截面測定之熱膨脹性微球之面積比率表示。於將特定截面中之黏著劑層之截面面積設為A，將該截面中之熱膨脹性微球之截面面積設為B之情形時，熱膨脹性微球之截面面積B之比率相對於黏著劑層之截面面積A較佳為3%～75%，更佳為3.5%～70%。於截面面積B之比率未達3%之情形時，有即便加熱而使熱膨脹微球膨脹，於黏著劑表面產生之凹凸亦不充分而無法獲得所需之剝離性之虞。另一方面，於截面面積B之比率超過75%之情形時，有黏著劑層之體積變化變得過大而產生基材與黏著劑層間之隆起、剝離之虞，又，有黏著劑層中之黏著劑含有比率較低而無法獲得所需之黏著力之虞。再者，熱膨脹性微球之截面面積B之比率例如可對藉由電子顯微鏡(例如Hitachi High-Technologies公司製造、商品名「S-3400N低真空掃描電子顯微鏡」)觀察黏著劑層之截面而獲得之圖像適當進行處理而求出。例如，可對該圖像進行紙輸出，由黏著劑層部分(即，包含熱膨脹性微球之黏著劑層整體)之紙重量a與僅將熱膨脹性微球部分切出後之紙之重量b藉由b/a×100之式而求出。
熱膨脹性微球之含有比率相對於黏著劑層之重量較佳為5重量%～95重量%，更佳為10重量%～70重量%，進而較佳為10重量%～50重量%。若為此種範圍，則能夠實現如上所述之熱膨脹性微球之截面面積B之比率。又，藉由將熱膨脹性微球之含有比率設為上述範圍，並且為了使黏著劑層中熱膨脹微球不會偏集存在而於塗佈步驟之前進行攪拌黏著劑層形成用組合物等之操作，能夠將熱膨脹性微球之截面面積B設為較佳之範圍。熱膨脹性微球之含有比率係藉由下述式而求出。熱膨脹性微球之重量係測定從黏著劑層中取出之熱膨脹性微球之重量而求出。
熱膨脹性微球之含有比率(重量%)＝熱膨脹性微球之重量/黏著劑層之重量×100
上述熱膨脹性微球可藉由任意適當之方法而製造。於一個實施形態中，上述熱膨脹性微球係藉由懸浮聚合法而獲得。懸浮聚合通常係使單體(殼形成材料)及有機溶劑分散至含有分散劑之水系分散介質中，於有機溶劑之存於下使單體聚合而進行。又，亦可利用使分散穩定之分散穩定劑。作為水系分散介質中之分散穩定劑，例如可列舉二氧化矽、氫氧化鎂、磷酸鈣、氫氧化鋁等無機微粒等。又，作為分散穩定助劑，例如可使用二乙醇胺與脂肪族二羧酸之縮合產物、聚乙烯基吡咯啶酮、甲基纖維素、聚環氧乙烷、聚乙烯醇、各種乳化劑等。
藉由上述懸浮聚合之聚合條件、混合成分之種類、添加量等，可控制粒徑、有機溶劑之含量等熱膨脹性微球之特性。例如藉由減少分散劑之添加量、減慢聚合時之攪拌速度等操作，能夠獲得大粒徑之熱膨脹性微球。又，若增多單體之調配量、或者減慢聚合時之攪拌速度，則能夠獲得殼之厚度較厚之熱膨脹性微球。
B-2.黏著劑
作為構成上述黏著劑層之黏著劑，只要可獲得本發明之效果，則可使用任意適當之黏著劑。作為上述黏著劑，例如可列舉丙烯酸系黏著劑、聚矽氧系黏著劑、乙烯基烷基醚系黏著劑、聚酯系黏著劑、聚醯胺系黏著劑、胺基甲酸酯系黏著劑、氟系黏著劑、苯乙烯-二烯嵌段共聚物系黏著劑、活性能量線硬化型黏著劑等。其中較佳為丙烯酸系黏著劑、橡膠系黏著劑或聚矽氧系黏著劑，更佳為丙烯酸系黏著劑。
上述黏著劑之凝膠分率較佳為20重量%～100重量%，更佳為30重量%～99重量%，進而較佳為50重量%～99重量%。於該凝膠分率未達20重量%之情形時，有即便熱膨脹微球膨脹而於黏著劑層表面產生凹凸，黏著劑層亦會流動而使凹凸於短時間內消失之虞。又，有由於聚合物分子排斥體積較小，熱膨脹性微球中之有機溶劑容易地透過聚合物分子鏈間，故而從A點達到B點之時間變長之虞。另一方面，於凝膠分率超過99重量%之情形時，有阻礙熱膨脹性微球之加熱膨脹而不產生充分之凹凸，或者即便產生凹凸之情形時亦會產生熱膨脹微球爆炸而使熱膨脹微球之殼或周圍之黏著劑層飛散等現象，使糊劑殘留性變差之虞。黏著劑之凝膠分率可藉由調節構成黏著劑之基礎聚合物之組成、黏著劑中添加之交聯劑之種類或含量、黏著賦予劑之種類或含量等而控制。凝膠分率之測定方法於後文敍述。
上述黏著劑中包含之基礎聚合物較佳為具有OH基或COOH基。其原因在於，若使用此種基礎聚合物，則能夠使用交聯劑來調整上述凝膠分率。又，藉由不與交聯劑反應之OH基或COOH基之量，能夠調整由氫鍵等分子間力產生之基礎聚合物之凝集性。藉此，能夠控制藉由熱膨脹性微球之膨脹而產生之黏著劑表面之凹凸形狀、及熱膨脹性微球中包含之有機溶劑之殼透過性。
具有OH基之上述基礎聚合物之羥值較佳為0～50，更佳為20～30。又，具有COOH基之上述基礎聚合物之酸值較佳為10～100，更佳為20～50。再者，黏著劑層中聚合物之羥值及酸值可萃取黏著劑層中之溶劑可溶成分而進行測定。具體而言，可藉由以下之方法萃取溶劑可溶成分。
(i)將黏著劑層投入至溶劑中，製備使黏著劑層中之溶劑可溶成分溶解至上述溶劑之溶液試樣。
作為溶劑，考慮極性等，可使用選自氯仿(CHCl3
)、二氯甲烷(CH2
Cl2
)、四氫呋喃(THF)、丙酮、二甲基亞碸(DMSO)、N,N-二甲基甲醯胺(DMF)、甲醇、乙醇、甲苯及水等中之任1種溶劑或以任意之比率包含2種以上之混合溶劑。
典型而言，於黏著劑層0.2 g左右中添加溶劑30 mL左右，於室溫至使用之溶劑之沸點左右之溫度區域下攪拌30分鐘～12小時左右。根據需要，例如於分析對象成分之萃取效率低之情形等時，亦可於分取上述溶液後之試樣中重新添加與分取之溶液大致等量之溶劑並進行攪拌，將該分取溶液之操作進行1次或反覆進行多次而製備溶液試樣。
(ii)可藉由蒸發等方法從上述溶液試樣中去除溶劑而提取溶劑可溶性聚合物。
再者，有於溶劑可溶性聚合物中包含未反應交聯劑之低分子量成分等不成為測定對象之溶劑可溶成分的情況。此時，以將上述溶液試樣投入至僅聚合物成分不溶之溶劑中之方法(再沈澱法)、或利用使用上述溶液試樣之凝膠過濾層析法進行分子量區分(分取液相層析法)等而調整僅由測定對象構成之溶劑可溶性聚合物。
(丙烯酸系黏著劑)
作為上述丙烯酸系黏著劑，例如可列舉以使用(甲基)丙烯酸烷基酯之1種或2種以上作為單體成分之丙烯酸系聚合物(均聚物或共聚物)作為基礎聚合物之丙烯酸系黏著劑等。作為(甲基)丙烯酸烷基酯之具體例，可列舉(甲基)丙烯酸甲酯、(甲基)丙烯酸乙酯、(甲基)丙烯酸丙酯、(甲基)丙烯酸異丙酯、(甲基)丙烯酸丁酯、(甲基)丙烯酸異丁酯、(甲基)丙烯酸第二丁酯、(甲基)丙烯酸第三丁酯、(甲基)丙烯酸戊酯、(甲基)丙烯酸己酯、(甲基)丙烯酸庚酯、(甲基)丙烯酸辛酯、(甲基)丙烯酸2-乙基己酯、(甲基)丙烯酸異辛酯、(甲基)丙烯酸壬酯、(甲基)丙烯酸異壬酯、(甲基)丙烯酸癸酯、(甲基)丙烯酸異癸酯、(甲基)丙烯酸十一烷基酯、(甲基)丙烯酸十二烷基酯、(甲基)丙烯酸十三烷基酯、(甲基)丙烯酸十四烷基酯、(甲基)丙烯酸十五烷基酯、(甲基)丙烯酸十六烷基酯、(甲基)丙烯酸十七烷基酯、(甲基)丙烯酸十八烷基酯、(甲基)丙烯酸十九烷基酯、(甲基)丙烯酸二十烷基酯等(甲基)丙烯酸C1-20烷基酯。其中，可較佳地使用具有碳數為4～18之直鏈狀或支鏈狀之烷基之(甲基)丙烯酸烷基酯。
於一個實施形態中，上述丙烯酸系聚合物包含源自均聚物之玻璃轉移溫度(Tg)達到80℃以上(較佳90℃以上、進而較佳100℃以上)之單體之結構單元。若使用此種聚合物，則能夠形成具有適度之彈性模數之黏著劑層。作為該單體，例如可列舉甲基丙烯酸環己酯(Tg：83℃)、丙烯酸二環戊酯(Tg：120℃)、甲基丙烯酸二環戊酯(Tg：175℃)、丙烯酸異𦯉酯(Tg：94℃)、甲基丙烯酸異𦯉酯(Tg：150℃)、甲基丙烯酸第三丁酯(Tg：118℃)、甲基丙烯酸甲酯(Tg：105℃)、三羥甲基丙烷三丙烯酸酯(Tg：
＞250℃)、苯乙烯(Tg：80℃)、丙烯腈(Tg：97℃)、N-丙烯醯基嗎啉(Tg：145℃)等。其中，較佳為甲基丙烯酸甲酯。源自均聚物之玻璃轉移溫度(Tg)達到80℃以上之單體之結構單元之含有比率相對於基礎聚合物(丙烯酸系聚合物)100重量份較佳為1重量份～20重量份，更佳為1重量份～10重量份。
上述丙烯酸系聚合物亦可以凝集力、耐熱性、交聯性等之改質為目的而根據需要包含與能夠與上述(甲基)丙烯酸烷基酯共聚之其他單體對應之單元。作為此種單體，例如可列舉丙烯酸、甲基丙烯酸、丙烯酸羧基乙酯、丙烯酸羧基戊酯、伊康酸、順丁烯二酸、反丁烯二酸、巴豆酸等含羧基單體；順丁烯二酸酐、伊康酸酐等酸酐單體；(甲基)丙烯酸羥基乙酯、(甲基)丙烯酸羥基丙酯、(甲基)丙烯酸羥基丁酯、(甲基)丙烯酸羥基己酯、(甲基)丙烯酸羥基辛酯、(甲基)丙烯酸羥基癸酯、(甲基)丙烯酸羥基月桂酯、甲基丙烯酸(4-羥基甲基環己基)甲酯等含羥基單體；苯乙烯磺酸、烯丙基磺酸、2-(甲基)丙烯醯胺-2-甲基丙磺酸、(甲基)丙烯醯胺丙磺酸、(甲基)丙烯酸磺基丙酯、(甲基)丙烯醯氧基萘磺酸等含磺酸基單體；(甲基)丙烯醯胺、N,N-二甲基(甲基)丙烯醯胺、N-丁基(甲基)丙烯醯胺、N-羥甲基(甲基)丙烯醯胺、N-羥甲基丙烷(甲基)丙烯醯胺等(N-取代)醯胺系單體；(甲基)丙烯酸胺基乙酯、(甲基)丙烯酸N,N-二甲基胺基乙酯、(甲基)丙烯酸第三丁基胺基乙酯等(甲基)丙烯酸胺基烷基酯系單體；(甲基)丙烯酸甲氧基乙酯、(甲基)丙烯酸乙氧基乙酯等(甲基)丙烯酸烷氧基烷基酯系單體；N-環己基順丁烯二醯亞胺、N-異丙基順丁烯二醯亞胺、N-月桂基順丁烯二醯亞胺、N-苯基順丁烯二醯亞胺等順丁烯二醯亞胺系單體；N-甲基伊康醯亞胺、N-乙基伊康醯亞胺、N-丁基伊康醯亞胺、N-辛基伊康醯亞胺、N-2-乙基己基伊康醯亞胺、N-環己基伊康醯亞胺、N-月桂基伊康醯亞胺等伊康醯亞胺系單體；N-(甲基)丙烯醯氧基亞甲基琥珀醯亞胺、N-(甲基)丙烯醯基-6-氧基六亞甲基琥珀醯亞胺、N-(甲基)丙烯醯基-8-氧基八亞甲基琥珀醯亞胺等琥珀醯亞胺系單體；乙酸乙烯酯、丙酸乙烯酯、N-乙烯基吡咯啶酮、甲基乙烯基吡咯啶酮、乙烯基吡啶、乙烯基哌啶酮、乙烯基嘧啶、乙烯基哌𠯤、乙烯基吡𠯤、乙烯基吡咯、乙烯基咪唑、乙烯基㗁唑、乙烯基嗎啉、N-乙烯基羧醯胺類、苯乙烯、α-甲基苯乙烯、N-乙烯基己內醯胺等乙烯基系單體；丙烯腈、甲基丙烯腈等氰基丙烯酸酯單體；(甲基)丙烯酸縮水甘油酯等含環氧基之丙烯酸系單體；(甲基)丙烯酸聚乙二醇酯、(甲基)丙烯酸聚丙二醇酯、(甲基)丙烯酸甲氧基乙二醇酯、(甲基)丙烯酸甲氧基聚丙二醇酯等二醇系丙烯酸酯單體；(甲基)丙烯酸四氫糠基酯、氟(甲基)丙烯酸酯、聚矽氧(甲基)丙烯酸酯等具有雜環、鹵素原子、矽原子等之丙烯酸酯系單體；己二醇二(甲基)丙烯酸酯、(聚)乙二醇二(甲基)丙烯酸酯、(聚)丙二醇二(甲基)丙烯酸酯、新戊二醇二(甲基)丙烯酸酯、季戊四醇二(甲基)丙烯酸酯、三羥甲基丙烷三(甲基)丙烯酸酯、季戊四醇三(甲基)丙烯酸酯、二季戊四醇六(甲基)丙烯酸酯、環氧丙烯酸酯、聚酯丙烯酸酯、丙烯酸胺基甲酸酯等多官能單體；異戊二烯、丁二烯、異丁烯等烯烴系單體；乙烯基醚等乙烯基醚系單體等。該等單體可單獨使用或將2種以上組合使用。
(添加劑)
上述黏著劑根據需要可包含任意適當之添加劑。作為該添加劑，例如可列舉交聯劑、黏著賦予劑、塑化劑、顏料、染料、填充劑、防老化劑、導電材、抗靜電劑、紫外線吸收劑、光穩定劑、剝離調整劑、軟化劑、界面活性劑、阻燃劑、抗氧化劑等。
作為上述黏著賦予劑，可使用任意適當之黏著賦予劑。作為黏著賦予劑，例如使用黏著賦予樹脂。作為黏著賦予樹脂之具體例，可列舉松香系黏著賦予樹脂(例如未改性松香、改性松香、松香酚系樹脂、松香酯系樹脂等)、萜烯系黏著賦予樹脂(例如萜烯系樹脂、萜酚系樹脂、苯乙烯改性萜烯系樹脂、芳香族改性萜烯系樹脂、氫化萜烯系樹脂)、烴系黏著賦予樹脂(例如脂肪族系烴樹脂、脂肪族系環狀烴樹脂、芳香族系烴樹脂(例如苯乙烯系樹脂、二甲苯系樹脂等)、脂肪族/芳香族系石油樹脂、脂肪族/脂環族系石油樹脂、氫化烴樹脂、香豆酮系樹脂、香豆酮茚系樹脂等)、酚系黏著賦予樹脂(例如烷基苯酚系樹脂、二甲苯甲醛系樹脂、可溶酚醛樹脂、酚醛清漆等)、酮系黏著賦予樹脂、聚醯胺系黏著賦予樹脂、環氧系黏著賦予樹脂、彈性體系黏著賦予樹脂等。
上述黏著賦予劑之添加量相對於基礎聚合物100重量份較佳為5重量份～100重量份，更佳為10重量份～50重量份。
作為上述交聯劑，例如除了異氰酸酯系交聯劑、環氧系交聯劑、三聚氰胺系交聯劑、過氧化物系交聯劑以外，可列舉脲系交聯劑、金屬烷氧化物系交聯劑、金屬螯合物系交聯劑、金屬鹽系交聯劑、碳二醯亞胺系交聯劑、㗁唑啉系交聯劑、氮丙啶系交聯劑、胺系交聯劑等。其中較佳為異氰酸酯系交聯劑或環氧系交聯劑。
作為上述異氰酸酯系交聯劑之具體例，可列舉伸丁基二異氰酸酯、六亞甲基二異氰酸酯等低級脂肪族多異氰酸酯類；伸環戊基二異氰酸酯、伸環己基二異氰酸酯、異佛爾酮二異氰酸酯等脂環族異氰酸酯類；2,4-甲苯二異氰酸酯、4,4'-二苯基甲烷二異氰酸酯、苯二甲基二異氰酸酯等芳香族異氰酸酯類；三羥甲基丙烷/甲伸苯基二異氰酸酯三聚物加成物(Nippon Polyurethane Industry公司製造、商品名「Coronate L」)、三羥甲基丙烷/六亞甲基二異氰酸酯三聚物加成物(Nippon Polyurethane Industry公司製造、商品名「Coronate HL」)、六亞甲基二異氰酸酯之異氰脲酸酯體(Nippon Polyurethane Industry公司製造、商品名「Coronate HX」)等異氰酸酯加成物等。異氰酸酯系交聯劑之含量可根據所需之黏著力、黏著劑層之彈性等而設定為任意適當之量，相對於基礎聚合物100重量份，代表性為0.1重量份～20重量份，更佳為0.5重量份～10重量份。
作為上述環氧系交聯劑，例如可列舉N,N,N',N'-四縮水甘油基間苯二甲胺、二縮水甘油基苯胺、1,3-雙(N,N-縮水甘油基胺基甲基)環己烷(MITSUBISHI GAS CHEMICAL公司製造、商品名「TETRAD C」)、1,6-己二醇二縮水甘油醚(共榮社化學公司製造、商品名「Epolight 1600」)、新戊二醇二縮水甘油醚(共榮社化學公司製造、商品名「Epolight 1500NP」)、乙二醇二縮水甘油醚(共榮社化學公司製造、商品名「Epolight 40E」)、丙二醇二縮水甘油醚(共榮社化學公司製造、商品名「Epolight 70P」)、聚乙二醇二縮水甘油醚(日本油脂公司製造、商品名「Epiol E-400」)、聚丙二醇二縮水甘油醚(日本油脂公司製造、商品名「Epiol P-200」)、山梨糖醇聚縮水甘油醚(Nagase ChemteX公司製造、商品名「Denacol EX-611」)、甘油聚縮水甘油醚(Nagase ChemteX 公司製造、商品名「Denacol EX-314」)、季戊四醇聚縮水甘油醚、聚甘油聚縮水甘油醚(Nagase ChemteX Corporation製造、商品名「Denacol EX-512」)、山梨糖醇酐聚縮水甘油醚、三羥甲基丙烷聚縮水甘油醚、己二酸二縮水甘油酯、鄰苯二甲酸二縮水甘油酯、三(2-羥基乙基)異氰脲酸三縮水甘油酯、間苯二酚二縮水甘油醚、雙酚-S-二縮水甘油醚、分子內具有2個以上之環氧基之環氧系樹脂等。環氧系交聯劑之含量可根據所需之黏著力、黏著劑層之彈性等而設為任意適當之量，相對於基礎聚合物100重量份，代表性為0.01重量份～10重量份，更佳為0.03重量份～5重量份。
作為上述塑化劑，可使用任意適當之塑化劑。作為塑化劑之具體例，例如可列舉偏苯三酸酯系塑化劑、均苯四甲酸酯系塑化劑、聚酯系塑化劑、己二酸系塑化劑等。其中較佳為偏苯三甲酸酯系塑化劑(例如偏苯三甲酸三正辛酯、偏苯三甲酸三(2-乙基己基)酯等)或均苯四甲酸酯系塑化劑(例如均苯四甲酸四正辛酯、均苯四甲酸四(2-乙基己基)酯等)。塑化劑可單獨使用或將2種以上組合使用。塑化劑之含量相對於基礎聚合物100重量份較佳為1重量份～20重量份，更佳為1重量份～5重量份。
B-3.黏著劑層之特性
23℃下之上述黏著劑層之利用奈米壓痕法所測得之彈性模數較佳為0.1 MPa～500 MPa，更佳為0.5 MPa～400 MPa。於一個實施形態中，使用彈性模數為0.8 MPa～50 MPa之黏著劑層。於黏著劑層之彈性模數未達0.1 MPa之情形時，有由於加熱時擴散至熱膨脹性微球外之有機溶劑迅速地透過黏著劑層，故而縮短從B點達到C點之時間之虞。另一方面，於彈性模數超過500 MPa之情形時，有阻礙熱膨脹性微球之膨脹、於熱膨脹性微球膨脹時黏著劑層被破壞等之虞。黏著劑層之彈性模數可藉由導入源自均聚物之玻璃轉移溫度(Tg)達到80℃以上之單體之結構單元、調整交聯度等而控制。再者，利用奈米壓痕法所測得之彈性模數係以距離黏著劑層表面3 μm左右內側並且不存在熱膨脹微球之部位(距離熱膨脹微球之殼表面1 μm以上之部位)作為測定對象，於負載時、除載時連續地測定將壓頭壓入至黏著劑層時對壓頭之負載荷重及壓入深度，並由所獲得之負載荷重-壓入深度曲線求出。本說明書中，利用奈米壓痕法所測得之彈性模數係指將測定條件設為負載/除載速度：1000 nm/s、壓入深度：800 nm而如上所述地測得之彈性模數。
上述黏著劑層與基材之抓固力較佳為4 N/20 mm以上，更佳為5 N/20 mm以上。若為此種範圍，則能夠獲得即便於熱膨脹性微球之膨脹後亦維持基材與黏著劑層之間之密接力而糊劑殘留較少之黏著帶。抓固力之測定方法於後文敍述。
於25℃之環境溫度下，使上述熱膨脹性微球發泡前之上述黏著劑層之算術平均高度Sa較佳為500 nm以下，更佳為400 nm以下，進而較佳為300 nm以下。若為此種範圍，則能夠獲得可降低於被黏著體之貼合面產生之凹凸之黏著帶。算術平均高度Sa可依據JIS B 0601：1994，使用雷射顯微鏡(Olympus製造之LEXT OLS-4000、圖像倍率432倍、測定面積640×640 μm(採樣速率0.625 μm))進行測定。
對本發明之黏著帶加熱而達到C點時之上述黏著劑層之算術平均高度Sa較佳為10 μm～50 μm，更佳為3 μm～30 μm。若為此種範圍，則能夠獲得於加熱後黏著力下降或消失，可使被黏著體容易地剝離之黏著帶。再者，於算術平均表面高度Sa超過50 μm之情形時，有產生凹凸時之發泡應力過大，即便未施加任何外力，被黏著體亦被吹飛等而對之後之被黏著體回收造成不良影響之虞。「對黏著帶加熱而達到C點時之黏著劑層之算術平均高度Sa」係於設定為C點溫度之加熱板上加熱了60±5秒之黏著帶(5 cm見方)之黏著劑層之算術平均高度Sa，可使用上述雷射顯微鏡而測定。再者，此處，黏著劑層之算術平均表面高度Sa係指於無被黏著體之狀態下加熱後之算術平均表面高度Sa。
上述黏著劑層之厚度較佳為5 μm～300 μm，更佳為15 μm～250 μm，進而較佳為30 μm～100 μm，尤佳為30 μm～60 μm。
B-4.其他成分
上述黏著劑層只要可獲得本發明之效果，則可進而包含任意適當之其他成分。作為其他之成分，例如可列舉珠。作為該珠，例如可列舉玻璃珠、樹脂珠等。若於黏著劑層中添加此種珠，則能夠提高黏著劑層之彈性模數，可獲得能夠以更良好之精度對被加工物進行加工之黏著帶。珠之平均粒徑例如為0.01 μm～50 μm。珠之添加量相對於黏著劑層100重量份例如為10重量份～200重量份，較佳為20重量份～100重量份。C. 基材
作為上述基材，例如可列舉樹脂片材、不織布、紙、金屬箔、織布、橡膠片材、發泡片材、該等之積層體(特別是包含樹脂片材之積層體)等。作為構成樹脂片材之樹脂，例如可列舉聚對苯二甲酸乙二酯(PET)、聚萘二甲酸乙二酯(PEN)、聚對苯二甲酸丁二酯(PBT)、聚乙烯(PE)、聚丙烯(PP)、乙烯-丙烯共聚物、乙烯-乙酸乙烯酯共聚物(EVA)、聚醯胺(尼龍)、全芳香族聚醯胺(aramid)、聚醯亞胺(PI)、聚氯乙烯(PVC)、聚苯硫醚(PPS)、氟系樹脂、聚醚醚酮(PEEK)等。作為不織布，可列舉包含馬尼拉麻之不織布等由具有耐熱性之天然纖維形成之不織布；聚丙烯樹脂不織布、聚乙烯樹脂不織布、酯系樹脂不織布等合成樹脂不織布等。作為金屬箔，可列舉銅箔、不鏽鋼箔、鋁箔等。作為紙，可列舉日本紙、牛皮紙等。
上述基材之厚度可根據所需之強度或柔軟性、以及使用目的等而設定為任意適當之厚度。基材之厚度較佳為1000 μm以下，更佳為1 μm～1000 μm，進而較佳為1 μm～500 μm，尤佳為3 μm～300 μm，最佳為5 μm～250 μm。
亦可對上述基材實施表面處理。作為表面處理，例如可列舉電暈處理、鉻酸處理、臭氧暴露、火焰暴露、高壓電擊暴露、游離輻射處理、利用底塗劑之塗敷處理等。
作為上述有機塗敷材料，例如可列舉塑膠硬塗材料II(CMC出版、(2004))中記載之材料。較佳為使用胺基甲酸酯系聚合物，更佳為使用聚丙烯酸胺基甲酸酯、聚酯胺基甲酸酯或該等之前驅物。其原因在於，對基材之塗敷、塗佈簡便，並且於工業上可選擇多種，能夠廉價地獲取。該胺基甲酸酯系聚合物例如係包含異氰酸酯單體與含醇性羥基之單體(例如含羥基之丙烯酸系化合物或含羥基之酯化合物)之反應混合物的聚合物。有機塗敷材料亦可包含多胺等鏈延長劑、防老化劑、氧化穩定劑等作為任意之添加劑。有機塗敷層之厚度並無特別限定，例如適宜為0.1 μm～10 μm左右，較佳為0.1 μm～5 μm左右，更佳為0.5 μm～5 μm左右。F. 黏著帶之製造方法
本發明之黏著帶可藉由任意適當之方法而製造。本發明之黏著帶可列舉例如於基材上直接塗敷包含黏著劑及熱膨脹性微球之黏著劑層形成用組合物之方法、或將於任意適當之基體上塗敷黏著劑層形成用組合物而形成之塗敷層轉印至基材上之方法等。黏著劑層形成用組合物可包含任意適當之溶劑。又，亦可於藉由包含黏著劑之組合物形成黏著劑塗敷層後，於該黏著劑塗敷層上撒上熱膨脹性微球，然後，使用層壓機等，將該熱膨脹性微球埋入至該塗敷層中，形成包含熱膨脹性微球之黏著劑層。
黏著劑層形成用組合物中之熱膨脹性微球之含有比率相對於黏著劑層形成用組合物之固形物成分重量較佳為5重量%～95重量%，更佳為10重量%～70重量%，進而較佳為10重量%～50重量%。
作為上述各組合物之塗敷方法，可採用任意適當之塗敷方法。例如，可於塗佈後乾燥而形成各層。作為塗佈方法，例如可列舉例如使用多層塗佈機(multicoter)、模塗機、凹版塗佈機、塗抹器等之塗佈方法。作為乾燥方法，例如可列舉自然乾燥、加熱乾燥等。加熱乾燥之情形時之加熱溫度可根據成為乾燥對象之物質之特性而設定為任意適當之溫度。G. 用途
本發明之黏著帶可良好地用作於製造電子零件時用於臨時固定電子零件材料之片材。於一個實施形態中，本發明之黏著帶可用作將電子零件材料切斷時之臨時固定片材。作為該電子零件材料，例如可列舉陶瓷電容器材料。若於本發明之黏著帶上臨時固定陶瓷電容器材料等電子零件材料，則能夠防止該材料之錯位，其結果，能夠以優異之精度將該材料切斷。作為上述切斷步驟中之切斷方法，可採用任意適當之切斷方法。
[實施例]
以下，藉由實施例對本發明進行具體說明，但本發明並不受該等實施例之限定。實施例中之評價方法如下所述。再者，下述評價中，使用剝離了隔離膜之黏著帶。又，實施例中，只要未特別明確記載，則「份」及「%」為重量基準。
[評價]
(1)黏著劑之基礎聚合物之羥值測定
(預處理)
(i)將黏著劑層之黏著劑2 g添加至氯仿300 ml中並進行1天回流。從所獲得之溶液中將污物等夾雜物過濾而去除，回收濾液。
(ii)將上述(i)中製備之氯仿溶液用1小時滴加至甲醇10 L中，回收所獲得之沈澱物。
(iii)將藉由上述(ii)之操作獲得之沈澱物溶解至氯仿300 ml中。將該溶液用1小時滴加至甲醇10 L中，回收所獲得之沈澱物。
(iv)將藉由上述(iii)之操作獲得之沈澱物再次溶解於氯仿300 ml中。將該溶液用1小時滴加至甲醇10 L中，回收所獲得之沈澱物。
(v)藉由GPC(Gel Permeation Chromatography，凝膠滲透層析法)測定(iv)中獲得之沈澱物，確認無重量平均分子量為2000以下之低分子量成分，將該沈澱物(基礎聚合物)作為羥值之測定用試樣。
(v')再者，於沈澱物中包含重量平均分子量為2000以下之低分子量化合物之情形時，重複上述(iv)之操作直至不含該低分子量化合物。
上述GPC測定係使用TOSOH公司製造之商品名「HLC-8120GPC」，使用聚苯乙烯作為分子量之標準物質，於以下之條件下進行。
＜GPC之測定條件＞
･樣品濃度：0.2重量%(四氫呋喃溶液)
･樣品注入量：10 μl
･溶離液：四氫呋喃(THF)
･流量(流速)：0.6 mL/min
･管柱溫度(測定溫度)：40℃
･管柱：商品名「TSKgelSuperHM-H/H4000/H3000/H2000」(TOSOH股份有限公司製造)
･檢測器：示差折射計(RI)
･標準聚苯乙烯：TOSOH公司製造之Tsk gel標準聚苯乙烯F-288、Tsk gel標準聚苯乙烯F-40、Tsk gel標準聚苯乙烯F-4、Tsk gel標準聚苯乙烯A-5000、Tsk gel標準聚苯乙烯A-500
(羥值之測定)
羥值係依據JIS K 0070-1992(乙醯化法)而進行評價。取乙酸酐約25 g，添加吡啶，將總量設為100 mL並充分攪拌，製作乙醯化試劑。
精確稱量而採集作為試樣之基礎聚合物約2 g置於平底燒瓶中，添加乙醯化試劑5 mL及吡啶10 mL，並安裝空氣冷凝管。以100℃加熱70分鐘後，放置冷卻，並從冷凝管上部添加甲苯(於黏著劑為甲苯難溶性之情形時為四氫呋喃)35 mL作為溶劑並攪拌後，添加水1 mL並加以攪拌而分解乙酸酐。為了使分解完全進行，再次加熱10分鐘並放置冷卻。
用乙醇5 mL清洗冷凝管並將其卸下，添加吡啶50 mL作為溶劑並攪拌。使用全移液管於該溶液中添加25 mL之0.5 mol/L氫氧化鉀乙醇溶液，利用0.5 mol/L氫氧化鉀乙醇溶液進行電位差滴定，由以下之式算出羥值。
羥值(mgKOH/g)＝(B－C)×f×28.05/S＋D
B：空白試驗中使用之0.5 mol/L氫氧化鉀乙醇溶液之量(mL)
C：試樣中使用之0.5mol/L氫氧化鉀乙醇溶液之量(mL)
f：0.5 mol/L氫氧化鉀乙醇溶液之因數
S：試樣之採集量(g)
D：酸值
(2)黏著劑之凝膠分率測定
採樣並精確稱量約0.1 g黏著劑層之黏著劑(試樣之重量)，將該樣品用網狀片材(商品名「NTF-1122」、日東電工股份有限公司製)包裹後，於約50 ml之甲苯中在室溫下浸漬1週。之後，將溶劑不溶成分(網狀片材之內容物)從甲苯中取出，於70℃下乾燥約2小時，稱量乾燥後之溶劑不溶成分(浸漬、乾燥後之重量)，由下述式(a)算出凝膠分率(重量%)。又，實施例7中，於該測定前，照射紫外線10 mJ/cm2
而使黏著劑進行紫外線硬化。比較例4中，於該測定前，照射紫外線500 mJ/cm2
而使黏著劑進行紫外線硬化。紫外線之照射係使用日東精機股份有限公司製造之「UM810」。
凝膠分率(重量%)＝[(浸漬、乾燥後之重量)/(試樣之重量)]×100 (a)
(3)黏著帶之熱機械分析
將黏著帶切斷成5 mm×5 mm，獲得測定樣品。使該測定樣品與測定裝置之探針側接觸，安裝於測定裝置。繼而，從室溫以特定之加溫速度進行加溫，獲得溫度-位移量(長度)曲線。
基於溫度-位移量曲線，求出從變形開始點(A點)達到膨脹而變形時之變形量成為最大變形量之一半之時間點(B點)之時間、從B點達到黏著帶之變形量成為最大之點(C點)之時間、A點時之溫度、B點時之溫度、及C點時之溫度。
＜分析條件＞
裝置名：Seiko Instruments Inc.公司製造、商品名「TMA/SS150」
測定模式：膨脹法，將黏著劑層設為探針側
試樣尺寸：5 mm見方
探針：1 mm
探針荷重：0 N
測定溫度範圍：室溫(25℃±5℃)～250℃
加溫速度：3℃/分鐘
(4)達到C點時之黏著劑層之算術平均高度Sa
將黏著帶切斷成5 cm×5 cm，獲得測定樣品。將該測定樣品於設定為C點溫度之加熱板上加熱60±5秒。加熱後，使用雷射顯微鏡(Olympus公司製造之LEXT OLS-4000、圖像倍率432倍、測定面積640×640 μm(採樣速率0.625 μm))，測定黏著劑層之算術平均高度Sa。
(5)黏著劑層之利用奈米壓痕法所測得之彈性模數
利用切片機沿厚度方向切斷黏著帶，藉由奈米壓痕儀對切斷面表面測定彈性模數。
更詳細而言，將距離黏著劑層表面3 μm左右並且不存在熱膨脹微球之部位(距離熱膨脹微球之殼表面1 μm以上之黏著劑)之切斷面表面作為測定對象。
藉由用測定裝置附帶之軟件(triboscan)對藉由將探針(壓頭)壓抵至測定對象而獲得之位移-荷重遲滯曲線進行數值處理而獲得彈性模數(10次測定之平均值)。
奈米壓痕儀裝置以及測定條件如下所述。
＜裝置及測定條件＞
裝置：奈米壓痕儀；Hysitron Inc公司製造之Triboindenter
測定方法：單一壓入法
測定溫度：23℃
壓入速度：約1000 nm/sec
壓入深度：約800 nm
探針：金剛石製、Berkovich型(三角錐型)
(6)基材-黏著劑層抓固力
於實施例記載之黏著帶之黏著劑層側用手壓輥貼合黏著帶(日東電工股份有限公司製造、No.315)之黏著面。繼而，於實施例記載之黏著帶之基材側貼合雙面膠帶(日東電工股份有限公司製造、No.5000N)，製成10 mm×70 mm之短條片。之後，對雙面膠帶之另一面貼合2 mm厚之SUS板而製成試驗體。
將所獲得之試驗體之黏著帶以50 mm/ mm進行180°剝離而撕下。
其結果，於僅黏著帶剝離之情形時、即未發生投錨破壞之情形時，設為合格(表中為〇)，於黏著劑層與黏著帶一起被撕下之情形時、發生投錨破壞之情形時，測定此時之剝離力。
再者，由於將黏著帶直接貼合於SUS板之情形時之黏著力為5 N/10 mm，故而上述試驗之合格品可謂具有5 N/10 mm以上之抓固力。
(7)糊劑殘留評價1(A點→B點時間與糊劑殘留之關係)
於4英吋之矽鏡面晶圓(裸晶圓、附定向平面)之鏡面整面用手壓輥貼合黏著帶，於室溫下放置1小時。
於設為各個黏著帶之B點溫度±5℃之加熱板上設置貼合有上述黏著帶之晶圓(以加熱板板面與未貼合黏著帶之晶圓面接觸之方式設置)，加熱10秒±1秒。
從加熱板上將附黏著帶之晶圓取出後，以黏著帶自然剝離之方式配置附黏著帶之晶圓(使黏著帶面為下側而將晶圓翻轉)，去除黏著帶。再者，於黏著帶未自然掉落而未被從晶圓去除之情形時，於該狀態下用鑷子夾住黏著帶而去除。又，實施例7中，於剝離操作前，照射紫外線10 mJ/cm2
而使黏著劑進行紫外線硬化。比較例4中，於該操作前，照射紫外線500 mJ/cm2
而使黏著劑進行紫外線硬化。紫外線之照射係使用日東精機股份有限公司製造之「UM810」。
用光學顯微鏡(Olympus Optical公司製造、物鏡5倍率、目鏡10倍率)對去除黏著帶後之鏡面之中央1×1 mm面內進行觀察，數出晶圓表面上之糊劑殘留(未於貼合黏著帶前之新品晶圓觀察到之大致點狀(粒狀)或不定形之圖像)之個數。
表中，將糊劑殘留個數為0～500個設為◎，將500～1000個設為〇，將1000～5000個設為△，將5000個以上設為×。
(8)糊劑殘留評價2(B點→C點時間與糊劑殘留之關係)
於4英吋之矽鏡面晶圓(裸晶圓、附定向平面)之鏡面整面用手壓輥貼合黏著帶，於室溫下放置1小時。
於設為各個黏著帶之B溫度±5℃之加熱板上設置貼合有上述黏著帶之晶圓(以加熱板板面與未貼合黏著帶之晶圓面接觸之方式設置)，加熱210±10秒。
從加熱板上將附黏著帶之晶圓取出後，以黏著帶自然剝離之方式配置附黏著帶之晶圓(使黏著帶面為地面側而將晶圓翻轉)而將黏著帶去除。再者，於黏著帶未自然掉落而未被從晶圓去除之情形時，於該狀態下用鑷子夾住黏著帶而去除。又，實施例7中，於剝離操作前，照射紫外線10 mJ/cm2
而使黏著劑進行紫外線硬化。比較例4中，於該操作前，照射紫外線500 mJ/cm2
而使黏著劑進行紫外線硬化。紫外線之照射係使用日東精機股份有限公司製造之「UM810」。
用光學顯微鏡(Olympus Optical公司製造、物鏡5倍率、目鏡10倍率)對去除黏著帶後之鏡面之中央1×1 mm面內進行觀察，數出晶圓表面上之糊劑殘留(未於貼合黏著帶前之新品晶圓觀察到之大致點狀(粒狀)或不定形之圖像)之個數。
表中，將糊劑殘留個數為0～500個設為◎，將500～1000個設為〇，將1000～5000個設為△，將5000個以上設為×。
[製造例1]熱膨脹性微球A之製作
將氯化鈉150 g、二氧化矽有效成分為20重量%之膠體二氧化矽(日產化學股份有限公司製造、商品名「SNOWTEX」)70 g、聚乙烯基吡咯啶酮1 g、及二乙醇胺與己二酸之縮合物0.5 g添加至蒸餾水600 g中後，將所獲得之混合物之pH值調整為2.8～3.2而獲得水性溶液。
於上述水性溶液中添加丙烯腈80 g、甲基丙烯酸甲酯40 g、及偏二氯乙烯130 g作為成為殼之材料之油系添加劑。進而，添加作為交聯劑之乙二醇二甲基丙烯酸酯1 g，獲得反應溶液。
將上述反應溶液添加至附均質混合機(特殊機化工業公司製造、商品名「TK Homomixer」)之耐壓反應容器中，進而將作為意欲內包於殼中之有機溶劑之異丁烷(沸點：-11.7℃)70 g及起始劑(二異丙氧基二碳酸酯)5 g添加至耐壓反應容器中。
使均質混合機以特定之初始攪拌條件(攪拌速度：6000 rpm、攪拌時間：2分鐘)旋轉而對上述混合物進行攪拌後，一面以80 rpm攪拌一面加溫至60℃而進行24小時反應。將藉由過濾反應後之反應溶液而獲得之固形物成分於氮氣氣流下在室溫下放置1週而獲得熱膨脹性微球。
再者，對所獲得之熱膨脹性微球用島津製作所製造之商品名「SALD-2000J」進行測定，結果平均粒徑為12.5 μm。又，藉由X射線CT(ZEISS公司製造之Xradia520versa(測定條件：管電壓60 KV、管電流83 μA、像素尺寸0.20 μm/pixel))，獲知熱膨脹微球內之溶劑為異丁烷，相對於熱膨脹性微球之重量包含13重量%。又，藉由上述X射線CT(computed tomography，電腦斷層攝影)進行測定，結果熱膨脹性微球之殼之厚度為2.8 μm。
[製造例2～11]熱膨脹性微球B～K
將水性溶液製備時之膠體二氧化矽之調配量、油系添加劑(丙烯腈、甲基丙烯腈、甲基丙烯酸異𦯉酯、甲基丙烯酸甲酯、偏二氯乙烯)之調配量、意欲內包於殼中之有機溶劑(異丁烷、異戊烷(沸點：27.7℃)、石油醚、異辛烷(沸點：99℃))、及聚合時之初始攪拌條件設為如表1所記載，除此以外，與製造例1同樣地製作熱膨脹性微球B～K。又，與製造例1同樣地測定熱膨脹性微球之平均粒徑、含有有機溶劑量、殼之厚度。將結果示於表1中。
[表1] 製造例1 製造例2 製造例3 製造例4 製造例5 製造例6 製造例7 製造例8 製造例9 製造例10 製造例11
熱膨脹性微球A 熱膨脹性微球B 熱膨脹性微球C 熱膨脹性微球D 熱膨脹性微球E 熱膨脹性微球F 熱膨脹性微球G 熱膨脹性微球H 熱膨脹性微球I 熱膨脹性微球J 熱膨脹性微球K
水性溶液 蒸餾水(重量份) 600 600 600 600 600 600 600 600 600 600 600
氯化鈉(重量份) 150 150 150 150 150 150 150 150 150 150 150
膠體二氧化矽(重量份) 70 70 70 70 70 70 70 40 40 40 70
聚乙烯基吡咯啶酮(重量份) 1 1 1 1 1 1 1 1 1 1 1
二乙醇胺/己二酸縮合物(重量份) 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5
油系添加劑(殼形成材料) 丙烯腈(重量份) 80 150 50 50 150 50 80 110 100 110 80
甲基丙烯腈(重量份) 0 0 100 130 80 50 0 55 60 0 0
甲基丙烯酸異𦯉酯(重量份) 0 0 0 0 10 0 0 0 0 0 0
甲基丙烯酸甲酯(重量份) 40 100 100 70 10 100 40 85 80 80 40
偏二氯乙烯(重量份) 130 0 0 0 0 0 130 0 0 0 130
有機溶劑(內包於殼中之有機溶劑) 異丁烷添加量(重量份) 70 50 0 0 0 150 70 20 0 0 0
異戊烷添加量(重量份) 0 0 60 0 20 0 0 0 0 70 70
石油醚添加量(重量份) 0 20 0 0 0 0 0 0 0 0 0
異辛烷添加量(重量份) 0 0 0 60 40 0 0 80 70 0 0
聚合條件 初始攪拌速度(rpm) 6000 6000 8000 12000 12000 6000 60000 3500 2500 3500 6000
初始攪拌時間(分鐘) 2 3 2 2 2 3 2 2 2 2 2
聚合溫度(℃) 60 60 60 60 60 60 60 60 60 60 60
聚合時間(小時) 24 24 24 24 24 24 24 24 24 24 24
特性 熱膨脹微球內溶劑含有率(重量%) 13 19 23 18 19 28 13 20 25 30 13
平均粒徑(μm) 12.5 20 30 20 23 35 12.5 30 38 34 12.5
殼厚度(μm) 2.8 2.1 2.5 3 2.5 2 2.8 2.5 1.5 0.8 2.8
殼樹脂之Tg(℃) 86 99 108 110 104 105 86 104 105 99 86
[實施例1]
將丙烯酸系共聚物(丙烯酸乙酯(EA)、甲基丙烯酸甲酯(MMA)、丙烯酸2-乙基己酯(2EHA)、及丙烯酸2-羥基乙酯(HEA)之共聚物、EA結構單元：MMA結構單元：2EHA結構單元：HEA結構單元＝60：5：30：5(重量比)；重量平均分子量：350000；羥值：24)100重量份、黏著賦予劑(YASUHARA CHEMICAL公司製造、商品名「YS POLYSTAR S145」)20重量份、異氰酸酯系交聯劑(TOSOH公司製造、商品名「Coronate L」)3重量份、熱膨脹性微球A 30重量份、及甲苯210重量份混合，製備黏著劑層形成用組合物。再者，丙烯酸系共聚物之重量平均分子量係藉由上述評價(1)中說明之方法而測定。
於作為基材之PET薄膜(厚度：50 μm)上塗佈上述黏著劑層形成用組合物並進行乾燥，獲得黏著帶(黏著劑層(厚度：30 μm)/基材)。再者，黏著劑之凝膠分率為85%。
將所獲得之黏著帶供於上述評價(3)～(8)。將結果示於表2中。
[實施例2～7、比較例1～4]
除了將丙烯酸系共聚物之組成、及黏著劑層形成用組合物之組成設為表2中所示之組成以外，與實施例1同樣地獲得黏著帶。將所獲得之黏著帶供於上述評價(3)～(8)。將結果示於表2中。再者，表2中，「交聯劑TETRAD C」為MITSUBISHI GAS CHEMICAL公司製造之環氧系交聯劑(商品名「TETRAD C」)，「DPHA」為二季戊四醇六丙烯酸酯(新中村工業化學公司製造)，「IRGACURE 184」為BASF Japan股份有限公司製造之光起始劑(商品名「IRGACURE 184」)。
[表2] 實施例1 實施例2 實施例3 實施例4 實施例5 實施例6 實施例7
黏著劑 基礎聚合物 單體調配比 丙烯酸乙酯(EA) 60 60 60 10
甲基丙烯酸甲酯(MMA) 5 5 5 5
丙烯酸丁酯(BA) 90 90 85
丙烯酸2-羥基乙酯(HEA) 5 5 5 5
丙烯酸2-乙基己酯(2EHA) 30 90 30 30
丙烯酸(AA) 5 5 10 5
重量平均分子量 350000 80000 700000 130000 350000 350000 600000
羥值 24 24 0 0 24 24 24
組成 基礎聚合物(重量份) 100 100 100 100 100 100 100
交聯劑Coronate L(重量份) 3 3 1 5 5 3
交聯劑TETRAD C(重量份) 0.5
黏著賦予劑YS POLYSTAR S145(重量份) 20 30 20 20
DPHA(重量份) 100
IRGACURE 184(重量份) 1
黏著劑凝膠分率(重量%) 85 80 85 89 85 85 99
熱膨脹性微球 種類 熱膨脹性微球A 熱膨脹性微球B 熱膨脹性微球C 熱膨脹性微球D 熱膨脹性微球E 熱膨脹性微球F 熱膨脹性微球G
熱膨脹性微球調配量(重量份) 30 25 30 50 25 50 30
黏著劑層厚度(μm) 30 30 30 30 30 30 30
基材 PET PET PET PET PET PET PET
基材厚度(μm) 50 50 50 50 50 50 50
達到C點時之黏著劑層之算術平均高度Sa( μm) 12.3 17.2 19.8 16.5 17.6 21.8 6.8
基材/黏著劑層間抓固力(N/20 mm) 〇 〇 〇 〇 〇 〇 〇
黏著劑層奈米壓痕儀彈性模數(Mpa) 2.0 3.2 7.1 0.8 9.8 10.4 360
熱機械分析 從A點達到B點之時間(秒) 147 131 75 100 120 180 151
從B點達到C點之時間(秒) 333 509 685 800 820 120 413
A點時之溫度(℃) 86 108 132 130 123 180 180
B點時之溫度(℃) 93 115 136 135 129 120 120
C點時之溫度(℃) 110 140 170 175 170 170 170
糊劑殘留之評價① ◎ ◎ 〇 ◎ ◎ ◎ ◎
糊劑殘留之評價② ◎ ◎ ◎ ◎ ◎ △ ◎
比較例1 比較例2 比較例3 比較例4
黏著劑 基礎聚合物 單體調配比 丙烯酸乙酯(EA) 60 10
甲基丙烯酸甲酯(MMA) 5 5
丙烯酸丁酯(BA) 90 85
丙烯酸2-羥基乙酯(HEA) 5
丙烯酸2-乙基己酯(2EHA) 30 90
丙烯酸(AA) 5 10 5
重量平均分子量 350000 700000 1300000 600000
羥值 24 0 0 24
組成 基礎聚合物(重量份) 100 100 100 100
交聯劑Coronate L(重量份) 3 3 3 3
交聯劑TETRAD C(重量份) 0.5 1
黏著賦予劑YS POLYSTAR S145(重量份) 20
DPHA(重量份) 100
IRGACURE 184(重量份) 1
黏著劑凝膠分率(重量%) 85 95 80 ≧99.9
熱膨脹性微球 種類 熱膨脹性微球H 熱膝脹性微球I 熱膨脹性微球J 熱膨脹性微球K
熱膨脹性微球調配量(重量份) 30 30 30 30
黏著劑層厚度(μm) 30 30 30 30
基材 PET PET PET PET
基材厚度(μm) 50 50 50 50
達到C點時之黏著劑層之算術平均高度Sa(μm) 20.1 30.7 23.2 5.9
基材/黏著劑層間抓固力(N/20 mm) 〇 〇 〇 〇
黏著劑層奈米壓痕儀彈性模數(Mpa) 2.0 7.2 6.5 1000 MPa以上
熱機械分析 從A點達到B點之時間(秒) 31 13 15 640
從B點達到C點之時間(秒) 109 188 150 160
A點時之溫度(℃) 155 150 110 125
B點時之溫度(℃) 157 151 112 155
C點時之溫度(℃) 162 160 115 180
糊劑殘留之評價① × × × ×
糊劑殘留之評價② × × × ×
A. The overall composition of the adhesive tape
Fig. 1 is a schematic cross-sectional view of an adhesive tape according to an embodiment of the present invention. The adhesive tape 100 includes a substrate 10 and an adhesive layer 20 disposed on at least one surface of the substrate 10 (single side in the example of the figure).
The adhesive layer included in the adhesive tape of the present invention includes thermally expandable microspheres. The heat-expandable microspheres can expand at a specific temperature. The adhesive layer containing such heat-expandable microspheres expands the heat-expandable microspheres by heating, and the adhesive surface (ie, the surface of the adhesive layer) produces unevenness, which reduces or disappears the adhesive force. When the adhesive tape of the present invention is used as a sheet for temporary fixation of a processed product during processing of electronic parts (such as ceramic capacitors), it exhibits the adhesiveness required for temporary fixation when the processed product is subjected to specific processing , When the adhesive tape is peeled from the processed object after processing, the adhesive force decreases or disappears by heating, showing good peelability. In one embodiment, the heat-expandable microsphere includes a shell and an organic solvent contained in the shell, and expands by the volatilization of the organic solvent.
In the adhesive tape of the present invention, when the adhesive tape is heated at a heating rate of 3°C/min in the thermomechanical analysis, the time from the point of initiation of deformation to the point in time when the amount of deformation during expansion and deformation becomes half of the maximum amount of deformation It is 45 seconds to 200 seconds. In more detail, it demonstrates using FIG. 2. FIG. Fig. 2 is a diagram showing an example of measurement results when the adhesive tape of an embodiment of the present invention is subjected to thermomechanical analysis, and shows the relationship between the temperature in the analysis and the amount of deformation (displacement) of the adhesive tape.
Heat the adhesive tape (heating rate: 3°C/min), and when it reaches a certain temperature, the adhesive tape begins to deform (expand). This time point is the aforementioned "deformation starting point". For the sake of convenience, the deformation starting point is set to point A. Furthermore, the deformation of the adhesive tape mainly depends on the expansion and contraction of the thermally expandable microspheres contained in the adhesive layer.
After point A, if heating continues, the adhesive tape (essentially heat-expandable microspheres) continues to expand, and then begins to shrink. For example, in the case of using heat-expandable microspheres containing a shell and an organic solvent contained in the shell, the heat-expandable microspheres are swelled by the volatilization of the organic solvent before reaching a certain temperature, and the time when the organic solvent is completely volatilized The point begins to shrink. The point where the contraction starts is the point where the expansion and the deformation of the adhesive tape become the maximum point. For convenience, set this point as point C.
Furthermore, from point A to point C, the point where the amount of deformation becomes half of the amount of deformation X (100 μm in the example in the figure) of point C (the time when the amount of deformation when expanded and deformed becomes half of the maximum amount of deformation) Point (50 μm in the example of the figure) is set to point B.
In the present invention, the time from point A to point B is 45 seconds to 200 seconds.
In addition, the analysis conditions in the above-mentioned thermomechanical analysis are as follows.
<Analysis conditions>
Device name: manufactured by Seiko Instruments Inc., product name "TMA/SS150"
Measurement mode: expansion method, set the adhesive layer to the probe side
Sample size: 5 mm square
Probe: 1 mm
Probe load: 0 N
Measuring temperature range: room temperature (25℃±5℃)～250℃
Heating speed: 3℃/min
In the present invention, by setting the time from point A to point B to be 45 seconds to 200 seconds, it is possible to obtain an adhesive tape with less paste residue when the adherend is peeled off. It is considered that from point A to point B, the adhesive layer is deformed (expanded) along with the expansion of the thermally expandable microspheres, but no unevenness is formed on the surface of the adhesive layer, or even if it is formed, the surface of the adhesive layer is almost the entire surface In a state of being pressed against the adhered body. It is considered that this state is a state in which the softening of the adhesive caused by heating promotes the residue of the paste on the adherend. In the present invention, by setting the time in this state (that is, the time from point A to point B) to 200 seconds or less, an adhesive tape with less paste residue can be obtained. On the other hand, when the time from point A to point B is less than 45 seconds, it means that the thermally expandable microspheres expand rapidly. In this case, the heat-expandable microspheres change rapidly, and there is a risk of problems such as flying of the adherend.
The time from point A to point B is preferably 70 seconds to 180 seconds, more preferably 90 seconds to 170 seconds. If it is such a range, the above-mentioned effect becomes remarkable.
The time from point B to point C is preferably 30 seconds or more, more preferably 60 seconds or more, still more preferably 180 seconds or more, and particularly preferably 200 seconds or more. After passing through point B and approaching point C, the heat-expandable microspheres further expand, and along with this, unevenness occurs on the surface of the adhesive layer, and the contact surface between the adhesive layer and the adherend gradually becomes smaller. As a result, the adhesive force of the adhesive tape decreases or disappears. On the other hand, if the thermally expandable microspheres begin to shrink after passing through point C, the contact surface between the adhesive layer and the adherend begins to increase, and the adhesive tape exhibits adhesiveness again. That is, before reaching point C from point B, the adhesive tape shows excellent peelability. By setting the time for this state to be longer than the specified time as described above, when the adhesive tape is used in the manufacturing steps of electronic parts, etc., the time taken for the peeling step of the adherend can be sufficiently secured. In addition, when the time from point B to point C is too short, it means that the heat-expandable microspheres are deformed abruptly, and there are adhesive layer components (such as adhesives) that cannot follow the rapid deformation of the heat-expandable microspheres. Separation, and the components of the adhesive layer separated from the small pieces may cause the paste to remain.
The upper limit of the time from point B to point C is, for example, 3600 seconds or less, preferably 1800 seconds or less, and more preferably 1000 seconds or less. If it is in this range, heat-expandable microspheres with an appropriate amount of organic solvent contained in it can be used.
In the above-mentioned thermomechanical analysis, the temperature at point A (also referred to as the temperature at point A) is preferably 30°C to 200°C, more preferably 40°C to 180°C, and particularly preferably 60°C to 180°C.
In the above-mentioned thermomechanical analysis, the temperature at point B (also referred to as the temperature at point B) is preferably 50°C to 250°C, more preferably 70°C to 200°C, and still more preferably 80°C to 150°C. By setting the temperature at point B to 50°C or higher, it is possible to prevent unwanted peeling performance of the adhesive tape (for example, peeling performance under high outside temperature conditions such as summer). In addition, when the temperature at point B exceeds 250°C, there is a risk of deterioration of the adhesive tape, fire, etc. during the period before the peelability is exhibited.
In the above-mentioned thermomechanical analysis, the temperature at point C (also referred to as the temperature at point C) is preferably 90°C to 350°C, more preferably 100°C to 200°C.
When the adhesive surface of the adhesive tape of the present invention is attached to a polyethylene terephthalate film (for example, a thickness of 25 μm) before the thermally expandable microspheres are foamed at an ambient temperature of 25°C, the adhesive force is preferably 0.2 N/20 mm or more, more preferably 0.2 N/20 mm to 20 N/20 mm, and still more preferably 2 N/20 mm to 10 N/20 mm. If it is such a range, for example, an adhesive tape useful as a temporary fixing sheet used in the manufacture of electronic parts can be obtained. The adhesive force in this manual refers to the adhesive force measured by the method according to JIS Z 0237: 2000 (laminating conditions: 2 kg roller reciprocating once, peeling speed: 300 mm/min, peeling angle 180°).
The thickness of the adhesive tape of the present invention is preferably 30 μm to 500 μm, more preferably 40 μm to 300 μm.B. Adhesive layer
The adhesive layer includes heat-expandable microspheres. Practically, the adhesive layer further contains an adhesive.
B-1. Thermally expandable microspheres
As the above-mentioned heat-expandable microspheres, any suitable heat-expandable microspheres can be used as long as they can be expanded by heating to the extent that irregularities are generated on the surface of the adhesive layer. As the thermally expandable microspheres, for example, microspheres containing a shell and a volatile substance (typically an organic solvent) contained in the shell can be used.
Examples of the material forming the shell include resin, glass, metal, and the like. Among them, resin is preferred. If resin is used, heat-expandable microspheres that are easily softened and expanded by heating can be obtained. In addition, since the shell formed of resin has a density close to that of the adhesive, it is also advantageous in that it is easily dispersed in the adhesive layer with high uniformity.
As the resin forming the aforementioned shell, for example, a resin having a structural unit derived from a monomer capable of radical polymerization can be used. Examples of the monomer include nitrile monomers such as acrylonitrile, methacrylonitrile, α-chloroacrylonitrile, α-ethoxyacrylonitrile, and fumaronitrile; acrylic acid, methacrylic acid, itaconic acid, Carboxylic acid monomers such as maleic acid, fumaric acid and citraconic acid; vinylidene chloride; vinyl acetate; methyl (meth)acrylate, ethyl (meth)acrylate, (meth) N-Butyl acrylate, isobutyl (meth)acrylate, tertiary butyl (meth)acrylate, isobutyl (meth)acrylate, cyclohexyl (meth)acrylate, benzyl (meth)acrylate, (Meth)acrylates such as β-carboxyethyl acrylate; styrene monomers such as styrene, α-methylstyrene, and chlorostyrene; acrylamide, substituted acrylamide, methacrylamide, substituted methyl Amine monomers such as acrylamide. The polymer containing these monomers may be a homopolymer or a copolymer.
In addition, the resin forming the shell may be a crosslinked body. Through cross-linking, the repelling free volume of the polymer can be adjusted, thereby controlling the diffusibility of the volatile substances contained in the package and the expansion of the shell. The crosslinked body may further include a structural unit derived from a monomer having two or more polymerizable double bonds in the molecule. In one embodiment, the above-mentioned monomer capable of radical polymerization is used in combination with a monomer having two or more polymerizable double bonds in the molecule. Examples of monomers having two or more polymerizable double bonds in the molecule include aromatic divinyl compounds such as divinylbenzene and divinylnaphthalene; allyl methacrylate, triacryloyl formal, Triallyl isocyanate, ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, 1,4-butanediol Di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, 1,10-decanediol di(meth)acrylate, PEG#200 di(meth)acrylate, PEG #400 di(meth)acrylate, PEG#600 di(meth)acrylate, neopentyl glycol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, trihydroxy Methylpropane tri(meth)acrylate, EO modified trimethylolpropane tri(meth)acrylate, glycerol di(meth)acrylate, dimethylol-tricyclodecane di(meth) Acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol hexa(meth)acrylate, neopentyl glycol acrylate benzoate, trimethylolpropane acrylate benzoic acid Ester, 2-hydroxy-3-propenoxypropyl (meth)acrylate, neopentyl glycol hydroxypivalate di(meth)acrylate, di-trimethylolpropane tetra(meth)acrylate , 2-Butyl-2-ethyl-1,3-propanediol di(meth)acrylate, polytetramethylene glycol di(meth)acrylate, phenyl glycidyl ether acrylate hexamethylene Diisocyanate urethane prepolymer, phenyl glycidyl ether acrylate toluene diisocyanate urethane prepolymer, pentaerythritol triacrylate hexamethylene diisocyanate urethane prepolymer, pentaerythritol Triacrylate toluene diisocyanate urethane prepolymer, pentaerythritol triacrylate isophorone diisocyanate urethane prepolymer, etc.
In one embodiment, the resin forming the shell includes a structural unit selected from the group consisting of iso-acrylate, a structural unit derived from methacrylonitrile, a structural unit derived from acrylonitrile, and a structural unit derived from methyl (meth)acrylate At least one of the structural unit, the structural unit derived from vinylidene chloride, and the structural unit derived from (meth)acrylic acid. If a resin with these structural units is used, it is possible to form a shell that is less soluble in the organic solvent contained in it, and the organic solvent is difficult to penetrate or infiltrate before heating. In addition, if the above-mentioned resin is used, it is possible to obtain thermally expandable microspheres with good deformability by heating. Furthermore, if the above-mentioned monomers are used, the thermal properties of the shell can be easily controlled by crosslinking or the like.
In one embodiment, it is preferable to use methacrylonitrile and/or acrylonitrile from the viewpoint of improving the resistance to the organic solvent contained therein. In the case of using these monomers, the total content ratio of the structural unit derived from methacrylonitrile and the structural unit derived from acrylonitrile is preferably 10% by weight to 99% by weight relative to 100% by weight of the resin forming the shell , More preferably 20% by weight to 99% by weight, particularly preferably 30% by weight to 95% by weight. If it is such a range, it is possible to obtain heat-expandable microspheres that are excellent in solvent resistance and are easy to appropriately set the B point temperature.
In one embodiment, it is preferable to use methyl (meth)acrylate from the viewpoint of the ease of control of the shell hardness. If methyl (meth)acrylate is used, for example, it can be combined with a crosslinkable monomer (for example, the above-mentioned monomer having two or more polymerizable double bonds in the molecule) and crosslinked by electron beam crosslinking, etc., can be easily crosslinked. The earth controls the hardness of the crust. In the case of using methyl (meth)acrylate, the content ratio of the methyl (meth)acrylate relative to 100% by weight of the resin forming the shell is preferably less than 65% by weight, more preferably 1% to 55% by weight % By weight, particularly preferably 1% by weight to 50% by weight.
In addition, in the case of imparting flexibility to the shell, it is preferable to use vinylidene chloride. The amount of vinylidene chloride used can be set to any appropriate amount according to the required glass transition temperature of the resin.
The thickness of the aforementioned shell is preferably 15 μm or less, more preferably 7 μm or less, still more preferably 5 μm or less, and particularly preferably 4 μm or less. If it is in this range, the time from point A to point B can be shortened, and the time from point A to point B can be easily set to 200 seconds or less as described above. In addition, the lower limit of the thickness of the shell is preferably 1 μm or more, more preferably 2 μm or more. If it is in this range, it is possible to produce heat-expandable microspheres that are not easily destroyed by accidental external forces or the like. Also, when the thickness of the shell is less than 1 μm, the physical properties of the shell change due to the wetting (diffusion) of the organic solvent contained in the shell. As a result, the time from point B to point C is significantly shorter Of danger. That is, by setting the upper and lower limits of the thickness of the shell to the above range, it can be easily obtained that the initial stage of heating (point A to point B) can be rapidly expanded, and the subsequent heating (point B to point C) can be used for a long time. Thermally expandable microspheres that maintain the expanded state. Furthermore, by setting the upper and lower limits of the thickness of the shell to the above-mentioned range, it is possible to reduce temperature unevenness at the time of foaming.
The glass transition temperature (Tg) of the resin constituting the shell is preferably 50°C to 250°C, more preferably 60°C to 200°C, and still more preferably 80°C to 150°C. If it is in this range, heat-expandable microspheres that can expand appropriately can be obtained, and if the heat-expandable microspheres are used, an adhesive tape whose B point temperature is appropriately set can be easily obtained. In addition, in this specification, when the resin is a copolymer, the above-mentioned glass transition temperature is calculated by the formula of Fox. Fox’s calculation formula is shown below, which is the glass transition temperature Tg (°C) of the copolymer and the glass transition temperature Tg of the homopolymer formed by the homopolymerization of the monomers (monomers) constituting the copolymer.i
(℃) The relational expression. Furthermore, in the following Fox formula, Tg (°C) represents the glass transition temperature of the copolymer, Wi
Indicates the weight fraction of monomer i, Tgi
(°C) represents the glass transition temperature of a homopolymer formed from monomer i.
1/(273＋Tg)=Σ(Wi
/(273＋Tgi
))
As the glass transition temperature of homopolymer formed by monomers, acrylonitrile homopolymer (AN): 97°C, methyl methacrylate homopolymer (MMA): 102°C, methacrylonitrile homopolymer (MAN ): 120°C, vinylidene chloride homopolymer: 75°C, isopropyl acrylate homopolymer: 97°C. In addition, as the glass transition temperature of homopolymers other than these, the value described in the "Polymer Handbook" (4th edition, John Wiley & Sons, Inc, 1999) can be used. Furthermore, in the case where there are multiple Tg values described in this document, the "conventional" value is adopted.
The absolute value of the difference between the glass transition temperature (Tg) of the resin forming the shell and the required point B temperature (|Tg-point B temperature|) is preferably 45°C or less, more preferably 5°C to 35°C. If a resin having such a glass transition temperature is used, it becomes easy to set the temperature of point B to the desired temperature.
The volatile substances contained in the aforementioned shell are typically organic solvents. Examples of the organic solvent include linear aliphatic hydrocarbons with 3 to 8 carbons and their fluorides, branched aliphatic hydrocarbons with 3 to 8 carbons and their fluorides, and 3 Straight-chain alicyclic hydrocarbons up to 8 and their fluorides, ether compounds having a hydrocarbon group with a carbon number of 2 to 8, or compounds in which a part of the hydrogen atoms of the hydrocarbon group is substituted by fluorine atoms, etc. In one embodiment, as the organic solvent, propane, cyclopropane, butane, cyclobutane, isobutane, pentane, cyclopentane, neopentane, isopentane, hexane, cyclohexane, 2 -Methylpentane, 2,2-dimethylbutane, heptane, cycloheptane, octane, cyclooctane, methylheptanes, trimethylpentanes, etc. only consist of hydrogen and carbon atoms Composition of hydrocarbons; C3
F7
OCH3
, C4
F9
OCH3
, C4
F9
OC2
H5
And other hydrofluoroethers. These organic solvents may use only 1 type, and may use 2 or more types together. The above organic solvent has the advantages of low affinity with the resin and/or adhesive forming the shell, difficult to dissolve the shell and/or adhesive, and difficult to change physical properties such as thermal properties. In addition, hydrocarbons composed only of hydrogen atoms and carbon atoms are preferable from the viewpoint of industrial use.
In one embodiment, branched hydrocarbons (for example, isobutane, isopentane, etc.) are used as hydrocarbons composed only of hydrogen atoms and carbon atoms. Branched chain hydrocarbons are not easy to be charged. If this solvent is used, it can prevent accidents such as fire caused by charging.
The boiling point of the aforementioned organic solvent is preferably -50°C to 100°C, more preferably -20°C to 100°C. If it is in this range, it is possible to obtain heat-expandable microspheres whose shells can expand well without being damaged. Furthermore, when the boiling point of the organic solvent is too low, the operation for suppressing volatilization during the manufacture of thermally expandable microspheres may become complicated.
The absolute value (|bp－Tg|) of the difference between the boiling point (bp) of the organic solvent and the glass transition temperature (Tg) of the resin constituting the shell is preferably 0°C to 150°C, more preferably more than 0°C and is 150°C or less, more preferably 5°C to 125°C. Furthermore, when two or more organic solvents (mixed solvents) are used, it is preferable that the difference between the boiling point of the solvent with the largest weight ratio and the glass transition temperature (Tg) of the resin constituting the shell is in the above range. If it is in this range, the time from point A to point B and the time from point B to point C can be adjusted appropriately and easily. The boiling point (bp) of the organic solvent is preferably lower than the glass transition temperature (Tg) of the resin forming the shell. If an organic solvent with a boiling point higher than the glass transition temperature of the shell is used, the shell may be destroyed by the pressure generated when the organic solvent is heated, or the adhesive may be scattered, which may hinder the function or effect expected in the present invention.
In addition, in most cases, the heat-expandable microspheres are exposed to the surrounding adhesive or sticking operations, etc., in an environment where the heat-expandable microspheres are crushed before heating. Therefore, it is preferable to have vapor pressure before heating so that the heat-expandable microspheres are not crushed.
The content ratio of the organic solvent is preferably 5% to 35% by weight, and more preferably 10% to 30% by weight relative to the weight before heating of the heat-expandable microspheres. If it is in this range, an adhesive tape in which the heat-expandable microspheres are dispersed in the adhesive layer with higher uniformity can be obtained. When the content ratio is less than 5% by weight, due to the low density and other reasons, the thermally expandable microspheres tend to accumulate on the surface of the adhesive layer during the manufacture of the adhesive layer, and become too large on the surface of the adhesive layer after heating. The danger of bumps. When the content ratio exceeds 35% by weight, the density is high and it settles in the adhesive layer. Even if heated, sufficient unevenness may not be formed on the surface of the adhesive layer and the required peelability may not be obtained. There is a risk of residual paste.
At an ambient temperature of 25°C, the average particle size (quantity basis) of the heat-expandable microspheres before foaming the heat-expandable microspheres is preferably 1 μm-40 μm, more preferably 5 μm-40 μm, and further Preferably, it is 10 μm to 40 μm. If it is in this range, heat-expandable microspheres with high dispersibility in the adhesive layer can be obtained. The adhesive layer containing heat-expandable microspheres in a state of high dispersibility has high uniformity of unevenness generated by heating, and can exhibit excellent peelability. The average particle diameter of the above-mentioned thermally expandable microspheres can be controlled by, for example, the conditions at the time of polymerizing the thermally expandable microspheres (details will be described later). Furthermore, in this specification, the average particle size can be measured by observing the used heat-expandable microspheres using an optical microscope or an electron microscope, or the heat-expandable microspheres taken out of the adhesive layer before heating. In addition, the average particle size can be measured by the particle size distribution measurement method in the laser scattering method. More specifically, the average particle size can be measured by dispersing the heat-expandable microspheres used in a specific solvent (for example, water) using a particle size distribution measuring device (for example, the trade name "SALD-2000J" manufactured by Shimadzu Corporation) .
In one embodiment, the content ratio of the heat-expandable microspheres is expressed by the area ratio of the heat-expandable microspheres measured from the cross section. When the cross-sectional area of the adhesive layer in a specific cross-section is set to A, and the cross-sectional area of the thermally expandable microspheres in the cross-section is set to B, the ratio of the cross-sectional area B of the thermally expandable microspheres to the adhesive layer The cross-sectional area A is preferably 3% to 75%, more preferably 3.5% to 70%. When the ratio of the cross-sectional area B is less than 3%, even if the heat-expandable microspheres are heated to expand, the unevenness generated on the surface of the adhesive may be insufficient and the desired peelability may not be obtained. On the other hand, when the ratio of the cross-sectional area B exceeds 75%, the volume change of the adhesive layer may become too large, causing swelling and peeling between the base material and the adhesive layer. The adhesive content is low and the required adhesive force may not be obtained. Furthermore, the ratio of the cross-sectional area B of the thermally expandable microspheres can be obtained by observing the cross-section of the adhesive layer with an electron microscope (for example, manufactured by Hitachi High-Technologies, trade name "S-3400N low vacuum scanning electron microscope") The image is obtained by appropriate processing. For example, the image can be outputted on paper, consisting of the paper weight a of the adhesive layer part (that is, the entire adhesive layer including heat-expandable microspheres) and the paper weight b after only the heat-expandable microspheres are cut out. It is calculated by the formula of b/a×100.
The content ratio of the thermally expandable microspheres relative to the weight of the adhesive layer is preferably 5% to 95% by weight, more preferably 10% to 70% by weight, and still more preferably 10% to 50% by weight. If it is in this range, the ratio of the cross-sectional area B of the thermally expandable microspheres as described above can be achieved. In addition, by setting the content ratio of the thermally expandable microspheres in the above range, and in order to prevent the thermally expandable microspheres from being concentrated in the adhesive layer, operations such as stirring the adhesive layer forming composition are performed before the coating step , The cross-sectional area B of the thermally expandable microspheres can be set to a preferable range. The content ratio of heat-expandable microspheres is calculated by the following formula. The weight of the heat-expandable microspheres is determined by measuring the weight of the heat-expandable microspheres taken out from the adhesive layer.
The content ratio of heat-expandable microspheres (weight%)=weight of heat-expandable microspheres/weight of adhesive layer×100
The above-mentioned thermally expandable microspheres can be manufactured by any appropriate method. In one embodiment, the above-mentioned heat-expandable microspheres are obtained by a suspension polymerization method. Suspension polymerization is usually performed by dispersing the monomer (shell-forming material) and an organic solvent in an aqueous dispersion medium containing a dispersant, and polymerizing the monomer in the presence of the organic solvent. In addition, a dispersion stabilizer that stabilizes the dispersion can also be used. Examples of the dispersion stabilizer in the aqueous dispersion medium include inorganic fine particles such as silica, magnesium hydroxide, calcium phosphate, and aluminum hydroxide. In addition, as the dispersion stabilizing aid, for example, a condensation product of diethanolamine and aliphatic dicarboxylic acid, polyvinylpyrrolidone, methylcellulose, polyethylene oxide, polyvinyl alcohol, various emulsifiers, and the like can be used.
The characteristics of thermally expandable microspheres such as particle size and organic solvent content can be controlled by the polymerization conditions of the above suspension polymerization, the types of mixing components, and the amount of addition. For example, by reducing the amount of dispersant added, slowing down the stirring speed during polymerization, etc., thermally expandable microspheres with large particle diameters can be obtained. In addition, if the blending amount of the monomer is increased or the stirring speed during polymerization is slowed down, heat-expandable microspheres with a thicker shell can be obtained.
B-2. Adhesive
As the adhesive constituting the above-mentioned adhesive layer, any suitable adhesive can be used as long as the effects of the present invention can be obtained. Examples of the above-mentioned adhesives include acrylic adhesives, silicone adhesives, vinyl alkyl ether adhesives, polyester adhesives, polyamide adhesives, and urethane adhesives. , Fluorine-based adhesives, styrene-diene block copolymer-based adhesives, active energy ray-curable adhesives, etc. Among them, acrylic adhesives, rubber adhesives or silicone adhesives are preferred, and acrylic adhesives are more preferred.
The gel fraction of the adhesive is preferably 20% by weight to 100% by weight, more preferably 30% by weight to 99% by weight, and still more preferably 50% by weight to 99% by weight. When the gel fraction is less than 20% by weight, even if the thermally-expandable microspheres expand to produce unevenness on the surface of the adhesive layer, the adhesive layer may flow and the unevenness may disappear in a short time. In addition, since the repelling volume of polymer molecules is small, the organic solvent in the thermally expandable microspheres easily penetrates between the polymer molecular chains, so the time from point A to point B may become longer. On the other hand, when the gel fraction exceeds 99% by weight, the thermal expansion of the heat-expandable microspheres may be hindered without sufficient unevenness, or even if unevenness occurs, the heat-expandable microspheres may explode and cause thermal expansion. The shell of the microsphere or the surrounding adhesive layer scattered, etc., which may make the paste residual property worse. The gel fraction of the adhesive can be controlled by adjusting the composition of the base polymer constituting the adhesive, the type or content of the crosslinking agent added to the adhesive, and the type or content of the adhesive imparting agent. The method for measuring the gel fraction is described later.
The base polymer contained in the aforementioned adhesive preferably has an OH group or a COOH group. The reason is that if such a base polymer is used, a crosslinking agent can be used to adjust the gel fraction. In addition, the amount of OH groups or COOH groups that do not react with the crosslinking agent can adjust the cohesiveness of the base polymer generated by intermolecular forces such as hydrogen bonds. Thereby, it is possible to control the unevenness of the surface of the adhesive produced by the expansion of the heat-expandable microspheres and the shell permeability of the organic solvent contained in the heat-expandable microspheres.
The hydroxyl value of the above-mentioned base polymer having an OH group is preferably 0-50, more preferably 20-30. In addition, the acid value of the above-mentioned base polymer having a COOH group is preferably 10-100, more preferably 20-50. Furthermore, the hydroxyl value and acid value of the polymer in the adhesive layer can be measured by extracting the solvent-soluble components in the adhesive layer. Specifically, the solvent-soluble components can be extracted by the following method.
(i) Put the adhesive layer into the solvent, and prepare a solution sample in which the solvent-soluble components in the adhesive layer are dissolved in the solvent.
As the solvent, considering the polarity, etc., it can be selected from chloroform (CHCl3
), dichloromethane (CH2
Cl2
), tetrahydrofuran (THF), acetone, dimethyl sulfide (DMSO), N,N-dimethylformamide (DMF), methanol, ethanol, toluene, water, etc. The ratio includes two or more mixed solvents.
Typically, add about 30 mL of solvent to about 0.2 g of the adhesive layer, and stir at a temperature range from room temperature to about the boiling point of the solvent used for about 30 minutes to 12 hours. If necessary, for example, when the extraction efficiency of the analysis target component is low, etc., the sample after the above-mentioned solution can be re-added with approximately the same amount of solvent as the aliquoted solution and stirred to obtain the aliquoted solution Perform this operation once or repeatedly to prepare solution samples.
(ii) The solvent-soluble polymer can be extracted by removing the solvent from the above-mentioned solution sample by methods such as evaporation.
In addition, there are cases where the solvent-soluble polymer contains low-molecular-weight components of the unreacted crosslinking agent and other solvent-soluble components that are not the subject of measurement. At this time, use the method of putting the above solution sample into a solvent in which only the polymer component is insoluble (reprecipitation method), or use the gel filtration chromatography method using the above solution sample to perform molecular weight discrimination (separate the liquid phase (Analysis method) and so on to adjust the solvent-soluble polymer composed only of the object to be measured.
(Acrylic adhesive)
As the above-mentioned acrylic adhesive, for example, an acrylic polymer (homopolymer or copolymer) using one or two or more of alkyl (meth)acrylates as a monomer component is used as a base polymer. Department of adhesives, etc. As specific examples of the alkyl (meth)acrylate, methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, isopropyl (meth)acrylate, (meth)acrylate Base) butyl acrylate, isobutyl (meth)acrylate, second butyl (meth)acrylate, tertiary butyl (meth)acrylate, amyl (meth)acrylate, hexyl (meth)acrylate , Heptyl (meth)acrylate, octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isooctyl (meth)acrylate, nonyl (meth)acrylate, (meth) Isononyl acrylate, decyl (meth)acrylate, isodecyl (meth)acrylate, undecyl (meth)acrylate, dodecyl (meth)acrylate, ten (meth)acrylate Trialkyl ester, tetradecyl (meth)acrylate, pentadecyl (meth)acrylate, hexadecyl (meth)acrylate, heptadecyl (meth)acrylate, ( C1-20 alkyl (meth)acrylates such as stearyl meth)acrylate, nonadecyl (meth)acrylate, and eicosanyl (meth)acrylate. Among them, alkyl (meth)acrylates having a linear or branched alkyl group having 4 to 18 carbon atoms can be preferably used.
In one embodiment, the above-mentioned acrylic polymer contains structural units derived from a monomer whose glass transition temperature (Tg) of the homopolymer reaches 80°C or higher (preferably 90°C or higher, and more preferably 100°C or higher). If such a polymer is used, an adhesive layer with a moderate elastic modulus can be formed. Examples of the monomer include cyclohexyl methacrylate (Tg: 83°C), dicyclopentyl acrylate (Tg: 120°C), dicyclopentyl methacrylate (Tg: 175°C), isoacrylate Esters (Tg: 94°C), iso-methacrylate (Tg: 150°C), tert-butyl methacrylate (Tg: 118°C), methyl methacrylate (Tg: 105°C), trimethylol Propane triacrylate (Tg:
>250°C), styrene (Tg: 80°C), acrylonitrile (Tg: 97°C), N-acrylomorpholine (Tg: 145°C), etc. Among them, methyl methacrylate is preferred. The content ratio of the structural unit of the monomer whose glass transition temperature (Tg) derived from the homopolymer reaches 80°C or higher is preferably 1 part by weight to 20 parts by weight relative to 100 parts by weight of the base polymer (acrylic polymer), More preferably, it is 1 part by weight to 10 parts by weight.
The above-mentioned acrylic polymer may contain units corresponding to other monomers copolymerizable with the above-mentioned alkyl (meth)acrylate for the purpose of modification of cohesive force, heat resistance, crosslinkability, etc., as necessary. Examples of such monomers include carboxyl group-containing monomers such as acrylic acid, methacrylic acid, carboxyethyl acrylate, carboxypentyl acrylate, itaconic acid, maleic acid, fumaric acid, and crotonic acid; Butenedioic anhydride, itaconic anhydride and other acid anhydride monomers; hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, hydroxybutyl (meth)acrylate, hydroxyhexyl (meth)acrylate, ( Hydroxy-containing monomers such as hydroxyoctyl meth)acrylate, hydroxydecyl (meth)acrylate, hydroxylauryl (meth)acrylate, (4-hydroxymethylcyclohexyl)methyl methacrylate, etc.; styrene sulfonic acid , Allylsulfonic acid, 2-(meth)acrylamide-2-methylpropanesulfonic acid, (meth)acrylamide propanesulfonic acid, (meth)sulfopropyl acrylate, (meth) Sulfonic acid group-containing monomers such as acryloxynaphthalenesulfonic acid; (meth)acrylamide, N,N-dimethyl(meth)acrylamide, N-butyl(meth)acrylamide, (N-substituted) amide-based monomers such as N-methylol (meth) acrylamide, N-methylolpropane (meth) acrylamide, etc.; (meth) amine ethyl acrylate, (meth) acrylamide (Meth)acrylic acid aminoalkyl ester monomers such as N,N-dimethylaminoethyl acrylate and tertiary butylaminoethyl (meth)acrylate; (meth)acrylic acid methoxy (Meth)acrylic acid alkoxyalkyl ester monomers such as methyl ethyl, ethoxy ethyl (meth)acrylate, etc.; N-cyclohexyl maleimide, N-isopropyl maleimide Maleic imine monomers such as diimidim, N-lauryl maleimide, N-phenyl maleimide, etc.; N-methyliconimide, N-Ethyl Ikonimines, N-Butyl Ikonimines, N-octyl Ikonimines, N-2-Ethylhexyl Ikonimines, N-Cyclohexyl Ikonimines Ikonimine monomers such as imine and N-lauryl Ikonimines; N-(meth)acryloyloxymethylene succinimide, N-(meth)acryloyl- Succinimidyl monomers such as 6-oxyhexamethylene succinimidyl and N-(meth)acryloyl-8-oxyoctamethylene succinimidyl; vinyl acetate, propionic acid Vinyl ester, N-vinylpyrrolidone, methylvinylpyrrolidone, vinylpyridine, vinylpiperidone, vinylpyrimidine, vinylpiperidine, vinylpyrrolidone, vinylpyrrole, vinylimidazole , Vinyl azole, vinyl morpholine, N-vinyl carboxamides, styrene, α-methyl styrene, N-vinyl caprolactam and other vinyl monomers; acrylonitrile, methyl Cyanoacrylate monomers such as acrylonitrile; acrylic monomers containing epoxy groups such as glycidyl (meth)acrylate; polyethylene glycol (meth)acrylate, polypropylene glycol (meth)acrylate, ( Glycol acrylate monomers such as methoxy glycol meth)acrylate and methoxy polypropylene glycol (meth)acrylate; tetrahydrofurfuryl (meth)acrylate and fluoro(meth)acrylate , Polysiloxane (meth)acrylate and other acrylate monomers with heterocycles, halogen atoms, silicon atoms, etc.; hexanediol di(meth)acrylate, (poly)ethylene glycol di(methyl) acrylic acid Esters, (poly)propylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, pentaerythritol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, pentaerythritol three Multifunctional monomers such as (meth)acrylate, dipentaerythritol hexa(meth)acrylate, epoxy acrylate, polyester acrylate, urethane acrylate, etc.; isoprene, butadiene, isobutylene, etc. Olefin-based monomers; vinyl ether-based monomers such as vinyl ethers, etc. These monomers can be used individually or in combination of 2 or more types.
(additive)
The above-mentioned adhesive may contain any appropriate additives as required. Examples of the additives include crosslinking agents, tackifiers, plasticizers, pigments, dyes, fillers, anti-aging agents, conductive materials, antistatic agents, ultraviolet absorbers, light stabilizers, peeling regulators, and softening agents. Agents, surfactants, flame retardants, antioxidants, etc.
As the above-mentioned adhesion-imparting agent, any suitable adhesion-imparting agent can be used. As the adhesion-imparting agent, for example, an adhesion-imparting resin is used. Specific examples of adhesion-imparting resins include rosin-based adhesion-imparting resins (e.g., unmodified rosin, modified rosin, rosin-phenol resin, rosin ester-based resins, etc.), terpene-based adhesion-imparting resins (e.g., terpene-based resins) , Terpene phenol resins, styrene modified terpene resins, aromatic modified terpene resins, hydrogenated terpene resins), hydrocarbon adhesion-imparting resins (e.g. aliphatic hydrocarbon resins, aliphatic cyclic hydrocarbons) Resins, aromatic hydrocarbon resins (such as styrene resins, xylene resins, etc.), aliphatic/aromatic petroleum resins, aliphatic/alicyclic petroleum resins, hydrogenated hydrocarbon resins, coumarone resins, Coumarone indene resins, etc.), phenolic adhesion-imparting resins (for example, alkylphenol resins, xylene formaldehyde resins, resol resins, novolacs, etc.), ketone-based adhesion-imparting resins, and polyamide-based adhesion-imparting resins Resin, epoxy-based adhesive imparting resin, elastic system adhesive imparting resin, etc.
The addition amount of the above-mentioned adhesion imparting agent is preferably 5 parts by weight to 100 parts by weight, and more preferably 10 parts by weight to 50 parts by weight relative to 100 parts by weight of the base polymer.
As the above-mentioned crosslinking agent, for example, in addition to an isocyanate-based crosslinking agent, an epoxy-based crosslinking agent, a melamine-based crosslinking agent, and a peroxide-based crosslinking agent, a urea-based crosslinking agent, a metal alkoxide-based crosslinking agent may be mentioned. Linking agent, metal chelate-based cross-linking agent, metal salt-based cross-linking agent, carbodiimide-based cross-linking agent, azoline-based cross-linking agent, aziridine-based cross-linking agent, amine-based cross-linking agent Wait. Among them, an isocyanate-based crosslinking agent or an epoxy-based crosslinking agent is preferred.
Specific examples of the above-mentioned isocyanate-based crosslinking agent include lower aliphatic polyisocyanates such as butylene diisocyanate and hexamethylene diisocyanate; cyclopentyl diisocyanate, cyclohexyl diisocyanate, and isophorone Alicyclic isocyanates such as diisocyanates; aromatic isocyanates such as 2,4-toluene diisocyanate, 4,4'-diphenylmethane diisocyanate, xylylene diisocyanate; trimethylolpropane/toluene Trimethylolpropane/hexamethylene diisocyanate trimer adduct (manufactured by Nippon Polyurethane Industry, trade name "Coronate L"), trimethylolpropane/hexamethylene diisocyanate trimer adduct (manufactured by Nippon Polyurethane Industry, product Name "Coronate HL"), isocyanurate body of hexamethylene diisocyanate (manufactured by Nippon Polyurethane Industry, trade name "Coronate HX") and other isocyanate adducts. The content of the isocyanate-based crosslinking agent can be set to any appropriate amount according to the required adhesive force, the elasticity of the adhesive layer, etc., relative to 100 parts by weight of the base polymer, typically 0.1 to 20 parts by weight, more It is preferably 0.5 parts by weight to 10 parts by weight.
Examples of the epoxy-based crosslinking agent include N,N,N',N'-tetraglycidyl metaxylylenediamine, diglycidylaniline, 1,3-bis(N,N-glycidyl Aminomethyl) cyclohexane (manufactured by MITSUBISHI GAS CHEMICAL, trade name "TETRAD C"), 1,6-hexanediol diglycidyl ether (manufactured by Kyoeisha Chemical Co., Ltd., trade name "Epolight 1600") , Neopentyl glycol diglycidyl ether (manufactured by Kyoeisha Chemical Company, trade name "Epolight 1500NP"), ethylene glycol diglycidyl ether (manufactured by Kyoeisha Chemical Company, trade name "Epolight 40E"), propylene glycol two Glycidyl ether (manufactured by Kyoeisha Chemical Co., Ltd., brand name "Epolight 70P"), polyethylene glycol diglycidyl ether (manufactured by Nippon Oil & Fat Co., Ltd., brand name "Epiol E-400"), polypropylene glycol diglycidyl ether ( Nippon Oil & Fat Co., Ltd., brand name "Epiol P-200"), sorbitol polyglycidyl ether (manufactured by Nagase ChemteX, brand name "Denacol EX-611"), glycerol polyglycidyl ether (manufactured by Nagase ChemteX, product Name "Denacol EX-314"), pentaerythritol polyglycidyl ether, polyglycerol polyglycidyl ether (manufactured by Nagase ChemteX Corporation, trade name "Denacol EX-512"), sorbitan polyglycidyl ether, trimethylol Propane polyglycidyl ether, diglycidyl adipate, diglycidyl phthalate, tris (2-hydroxyethyl) isocyanurate triglycidyl ester, resorcinol diglycidyl ether, double Phenol-S-diglycidyl ether, epoxy resins with two or more epoxy groups in the molecule, etc. The content of the epoxy-based crosslinking agent can be set to any appropriate amount according to the required adhesive force, elasticity of the adhesive layer, etc., with respect to 100 parts by weight of the base polymer, typically 0.01 parts by weight to 10 parts by weight, More preferably, it is 0.03 parts by weight to 5 parts by weight.
As the above-mentioned plasticizer, any appropriate plasticizer can be used. Specific examples of the plasticizer include, for example, trimellitate-based plasticizers, pyromellitic acid-based plasticizers, polyester-based plasticizers, and adipic acid-based plasticizers. Among them, preferred are trimellitate-based plasticizers (e.g., tri-n-octyl trimellitate, tris(2-ethylhexyl) trimellitate, etc.) or pyromellitic acid ester-based plasticizers (For example, tetra-n-octyl pyromellitic acid, tetrakis(2-ethylhexyl) pyromellitic acid, etc.). The plasticizer can be used alone or in combination of two or more kinds. The content of the plasticizer is preferably 1 part by weight to 20 parts by weight, and more preferably 1 part by weight to 5 parts by weight relative to 100 parts by weight of the base polymer.
B-3. The characteristics of the adhesive layer
The elastic modulus of the adhesive layer at 23° C. measured by the nanoindentation method is preferably 0.1 MPa to 500 MPa, more preferably 0.5 MPa to 400 MPa. In one embodiment, an adhesive layer with an elastic modulus of 0.8 MPa-50 MPa is used. When the elastic modulus of the adhesive layer does not reach 0.1 MPa, the organic solvent that diffuses out of the thermally expandable microspheres rapidly penetrates the adhesive layer during heating, which may shorten the time from point B to point C. On the other hand, when the elastic modulus exceeds 500 MPa, the expansion of the heat-expandable microspheres may be hindered, and the adhesive layer may be destroyed when the heat-expandable microspheres expand. The elastic modulus of the adhesive layer can be controlled by introducing structural units derived from homopolymer monomers whose glass transition temperature (Tg) is above 80°C, adjusting the degree of crosslinking, and so on. Furthermore, the modulus of elasticity measured by the nanoindentation method is based on the position that is about 3 μm away from the surface of the adhesive layer and where there are no thermally-expandable microspheres (the part that is more than 1 μm away from the shell surface of the thermally-expandable microsphere) is taken as The object to be measured is to continuously measure the load and indentation depth of the indenter when the indenter is pressed into the adhesive layer during loading and unloading, and obtain the load from the obtained load-indentation depth curve. In this manual, the elastic modulus measured by the nanoindentation method refers to the elasticity measured as described above with the measurement conditions set to load/unload speed: 1000 nm/s, indentation depth: 800 nm Modulus.
The gripping force between the adhesive layer and the substrate is preferably 4 N/20 mm or more, more preferably 5 N/20 mm or more. If it is in this range, it is possible to obtain an adhesive tape that maintains the adhesive force between the substrate and the adhesive layer even after the expansion of the thermally expandable microspheres, and has less paste residue. The method of measuring the holding force is described later.
At an ambient temperature of 25° C., the arithmetic average height Sa of the adhesive layer before foaming the thermally expandable microspheres is preferably 500 nm or less, more preferably 400 nm or less, and still more preferably 300 nm or less. If it is in this range, it is possible to obtain an adhesive tape that can reduce unevenness generated on the bonding surface of the adherend. The arithmetic mean height Sa can be measured in accordance with JIS B 0601: 1994, using a laser microscope (LEXT OLS-4000 manufactured by Olympus, image magnification 432 times, measurement area 640×640 μm (sampling rate 0.625 μm)).
The arithmetic average height Sa of the adhesive layer when the adhesive tape of the present invention is heated to reach point C is preferably 10 μm-50 μm, more preferably 3 μm-30 μm. If it is in this range, it is possible to obtain an adhesive tape in which the adhesive force decreases or disappears after heating, and the adherend can be easily peeled off. In addition, when the arithmetic average surface height Sa exceeds 50 μm, the foaming stress at the time of unevenness is too large, even if no external force is applied, the adherend is blown away, etc., which will cause problems in the subsequent recovery of the adherend. The fear of impact. "The arithmetic mean height Sa of the adhesive layer when the adhesive tape is heated to reach C point" is the value of the adhesive layer (5 cm square) of the adhesive tape heated for 60±5 seconds on the hot plate set at the C point temperature The arithmetic average height Sa can be measured using the above-mentioned laser microscope. Furthermore, here, the arithmetic average surface height Sa of the adhesive layer refers to the arithmetic average surface height Sa after heating in a state without an adherend.
The thickness of the adhesive layer is preferably 5 μm to 300 μm, more preferably 15 μm to 250 μm, still more preferably 30 μm to 100 μm, and particularly preferably 30 μm to 60 μm.
B-4. Other ingredients
The above-mentioned adhesive layer may further contain any appropriate other components as long as the effects of the present invention can be obtained. Examples of other components include beads. Examples of the beads include glass beads and resin beads. If such beads are added to the adhesive layer, the elastic modulus of the adhesive layer can be increased, and an adhesive tape that can process the workpiece with better precision can be obtained. The average particle diameter of the beads is, for example, 0.01 μm to 50 μm. The addition amount of the beads is, for example, 10 parts by weight to 200 parts by weight, preferably 20 parts by weight to 100 parts by weight with respect to 100 parts by weight of the adhesive layer.C. Substrate
Examples of the above-mentioned substrate include resin sheets, nonwoven fabrics, paper, metal foils, woven fabrics, rubber sheets, foamed sheets, laminates of these (especially laminates containing resin sheets), and the like. As the resin constituting the resin sheet, for example, polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polybutylene terephthalate (PBT), polyethylene (PE) ), polypropylene (PP), ethylene-propylene copolymer, ethylene-vinyl acetate copolymer (EVA), polyamide (nylon), wholly aromatic polyamide (aramid), polyimide (PI), Polyvinyl chloride (PVC), polyphenylene sulfide (PPS), fluorine-based resin, polyether ether ketone (PEEK), etc. Examples of non-woven fabrics include non-woven fabrics made of natural fibers having heat resistance such as non-woven fabrics containing manila hemp; synthetic resin non-woven fabrics such as polypropylene resin non-woven fabrics, polyethylene resin non-woven fabrics, and ester-based resin non-woven fabrics. As metal foil, copper foil, stainless steel foil, aluminum foil, etc. are mentioned. As the paper, Japanese paper, kraft paper, etc. can be cited.
The thickness of the above-mentioned base material can be set to any appropriate thickness according to the required strength or flexibility, the purpose of use, and the like. The thickness of the substrate is preferably 1000 μm or less, more preferably 1 μm to 1000 μm, still more preferably 1 μm to 500 μm, particularly preferably 3 μm to 300 μm, most preferably 5 μm to 250 μm.
It is also possible to perform surface treatment on the above-mentioned base material. As the surface treatment, for example, corona treatment, chromic acid treatment, ozone exposure, flame exposure, high voltage electric shock exposure, ionizing radiation treatment, coating treatment with a primer, etc. can be cited.
Examples of the above-mentioned organic coating materials include materials described in Plastic Hard Coating Materials II (CMC Publishing, (2004)). Preferably, a urethane-based polymer is used, and more preferably, a polyacrylate urethane, polyester urethane, or these precursors are used. The reason is that the coating and coating of the substrate are simple, and it is industrially selectable and can be obtained inexpensively. The urethane-based polymer is, for example, a polymer comprising a reaction mixture of an isocyanate monomer and an alcoholic hydroxyl-containing monomer (for example, a hydroxyl-containing acrylic compound or a hydroxyl-containing ester compound). The organic coating material may also contain chain extenders such as polyamines, anti-aging agents, oxidation stabilizers, etc. as optional additives. The thickness of the organic coating layer is not particularly limited. For example, it is preferably about 0.1 μm to 10 μm, preferably about 0.1 μm to 5 μm, and more preferably about 0.5 μm to 5 μm.F. Manufacturing method of adhesive tape
The adhesive tape of the present invention can be manufactured by any appropriate method. The adhesive tape of the present invention may include, for example, a method of directly coating a composition for forming an adhesive layer containing an adhesive and heat-expandable microspheres on a substrate, or applying a composition for forming an adhesive layer on any suitable substrate And the method of transferring the formed coating layer to the substrate, etc. The composition for forming an adhesive layer may contain any suitable solvent. In addition, after forming the adhesive coating layer from the composition containing the adhesive, sprinkle heat-expandable microspheres on the adhesive coating layer, and then use a laminator or the like to apply the heat-expandable microspheres It is embedded in the coating layer to form an adhesive layer containing heat-expandable microspheres.
The content ratio of the heat-expandable microspheres in the adhesive layer forming composition relative to the weight of the solid content of the adhesive layer forming composition is preferably 5% to 95% by weight, more preferably 10% to 70% by weight %, more preferably 10% by weight to 50% by weight.
As the application method of each of the above-mentioned compositions, any appropriate application method can be adopted. For example, each layer can be formed by drying after coating. As the coating method, for example, a coating method using a multicoter, die coater, gravure coater, applicator, etc. can be mentioned. As a drying method, natural drying, heat drying, etc. are mentioned, for example. In the case of heating and drying, the heating temperature can be set to any appropriate temperature according to the characteristics of the substance to be dried.G. use
The adhesive tape of the present invention can be well used as a sheet for temporarily fixing materials of electronic parts when manufacturing electronic parts. In one embodiment, the adhesive tape of the present invention can be used as a temporary fixing sheet when cutting electronic component materials. As this electronic component material, a ceramic capacitor material is mentioned, for example. If an electronic component material such as a ceramic capacitor material is temporarily fixed to the adhesive tape of the present invention, the material can be prevented from being dislocated, and as a result, the material can be cut with excellent accuracy. As the cutting method in the above cutting step, any appropriate cutting method can be adopted.
[Example]
Hereinafter, the present invention will be described in detail with examples, but the present invention is not limited by these examples. The evaluation methods in the examples are as follows. In addition, in the following evaluation, the adhesive tape from which the release film was peeled was used. In addition, in the examples, as long as there is no clear description in particular, "parts" and "%" are based on weight.
[Evaluation]
(1) Determination of the hydroxyl value of the base polymer of the adhesive
(Pretreatment)
(i) Add 2 g of the adhesive of the adhesive layer to 300 ml of chloroform and reflux for 1 day. From the obtained solution, impurities such as dirt are filtered and removed, and the filtrate is recovered.
(ii) The chloroform solution prepared in (i) above was added dropwise to 10 L of methanol over 1 hour, and the obtained precipitate was recovered.
(iii) Dissolve the precipitate obtained by the operation of (ii) above in 300 ml of chloroform. This solution was added dropwise to 10 L of methanol over 1 hour, and the obtained precipitate was recovered.
(iv) Dissolve the precipitate obtained by the operation of (iii) above in 300 ml of chloroform again. This solution was added dropwise to 10 L of methanol over 1 hour, and the obtained precipitate was recovered.
(v) Measure the precipitate obtained in (iv) by GPC (Gel Permeation Chromatography), confirm that there is no low molecular weight component with a weight average molecular weight of 2000 or less, and then the precipitate (base polymer) As a sample for the measurement of hydroxyl value.
(v') Furthermore, when a low molecular weight compound with a weight average molecular weight of 2000 or less is contained in the precipitate, the operation of (iv) above is repeated until the low molecular weight compound is not contained.
The above-mentioned GPC measurement was performed under the following conditions using the trade name "HLC-8120GPC" manufactured by TOSOH, and polystyrene as the molecular weight standard substance.
＜GPC measurement conditions＞
･Sample concentration: 0.2% by weight (tetrahydrofuran solution)
･Sample injection volume: 10 μl
･Chaotrope: Tetrahydrofuran (THF)
･Flow (flow rate): 0.6 mL/min
･Column temperature (measurement temperature): 40°C
･Column: Trade name "TSKgelSuperHM-H/H4000/H3000/H2000" (manufactured by TOSOH Co., Ltd.)
･Detector: Differential Refractometer (RI)
･Standard polystyrene: Tsk gel standard polystyrene F-288, Tsk gel standard polystyrene F-40, Tsk gel standard polystyrene F-4, Tsk gel standard polystyrene A-5000, manufactured by TOSOH Tsk gel standard polystyrene A-500
(Determination of Hydroxyl Value)
The hydroxyl value is evaluated based on JIS K 0070-1992 (acetylation method). Take about 25 g of acetic anhydride, add pyridine, set the total amount to 100 mL, and stir well to make an acetylation reagent.
Accurately weigh and collect about 2 g of the base polymer as a sample, place it in a flat-bottomed flask, add 5 mL of acetylation reagent and 10 mL of pyridine, and install an air condenser. After heating at 100°C for 70 minutes, let it cool down, and add 35 mL of toluene (tetrahydrofuran when the adhesive is poorly soluble in toluene) as a solvent from the upper part of the condenser. After stirring, add 1 mL of water and stir to decompose the ethyl acetate. Acid anhydride. In order to complete the decomposition, heat again for 10 minutes and leave to cool.
Wash the condenser tube with 5 mL of ethanol and remove it, add 50 mL of pyridine as a solvent and stir. Use a full pipette to add 25 mL of 0.5 mol/L potassium hydroxide ethanol solution to the solution, use 0.5 mol/L potassium hydroxide ethanol solution for potentiometric titration, and calculate the hydroxyl value from the following formula.
Hydroxyl value (mgKOH/g)=(B－C)×f×28.05/S＋D
B: The amount of 0.5 mol/L potassium hydroxide ethanol solution used in the blank test (mL)
C: The amount of 0.5mol/L potassium hydroxide ethanol solution used in the sample (mL)
f: the factor of 0.5 mol/L potassium hydroxide ethanol solution
S: The amount of sample collected (g)
D: acid value
(2) Determination of gel fraction of adhesive
Sampling and accurately weighing approximately 0.1 g of the adhesive layer of the adhesive (the weight of the sample), wrap the sample with a mesh sheet (trade name "NTF-1122", manufactured by Nitto Denko Co., Ltd.), and then approximately Soak in 50 ml of toluene at room temperature for 1 week. After that, the solvent-insoluble components (contents of the mesh sheet) were taken out of the toluene and dried at 70°C for about 2 hours, and the solvent-insoluble components after drying (weight after immersion and drying) were weighed by the following formula (a) Calculate the gel fraction (weight%). Also, in Example 7, before the measurement, 10 mJ/cm of ultraviolet rays were irradiated2
The adhesive is cured by ultraviolet rays. In Comparative Example 4, before the measurement, 500 mJ/cm of ultraviolet rays were irradiated2
The adhesive is cured by ultraviolet rays. The ultraviolet radiation is used "UM810" manufactured by Nitto Seiki Co., Ltd.
Gel fraction (weight%)=[(weight after immersion and drying)/(weight of sample)]×100 (a)
(3) Thermomechanical analysis of the adhesive tape
The adhesive tape was cut into 5 mm×5 mm to obtain a measurement sample. The measurement sample is brought into contact with the probe side of the measurement device and mounted on the measurement device. Then, heating is performed at a specific heating rate from room temperature to obtain a temperature-displacement (length) curve.
Based on the temperature-displacement curve, find the time from the starting point of deformation (point A) to the point in time when the deformation becomes half of the maximum deformation (point B), and the amount of deformation from point B to the adhesive tape The time to become the maximum point (point C), the temperature at point A, the temperature at point B, and the temperature at point C.
<Analysis conditions>
Device name: manufactured by Seiko Instruments Inc., product name "TMA/SS150"
Measurement mode: expansion method, set the adhesive layer to the probe side
Sample size: 5 mm square
Probe: 1 mm
Probe load: 0 N
Measuring temperature range: room temperature (25℃±5℃)～250℃
Heating speed: 3℃/min
(4) The arithmetic average height of the adhesive layer when reaching point C Sa
The adhesive tape was cut into 5 cm×5 cm to obtain a measurement sample. The measurement sample is heated for 60±5 seconds on a hot plate set at the temperature of point C. After heating, a laser microscope (LEXT OLS-4000 manufactured by Olympus, image magnification 432 times, measurement area 640×640 μm (sampling rate 0.625 μm)) was used to measure the arithmetic average height Sa of the adhesive layer.
(5) The elastic modulus of the adhesive layer measured by the nanoindentation method
The adhesive tape is cut in the thickness direction with a microtome, and the elastic modulus of the cut surface is measured by a nanoindenter.
In more detail, the cut surface of the cut surface at a distance of about 3 μm from the surface of the adhesive layer and no thermally expandable microspheres (adhesive at a distance of more than 1 μm from the shell surface of the thermally expandable microspheres) was used as the measurement object.
The elastic modulus (average value of 10 measurements) is obtained by numerically processing the displacement-load hysteresis curve obtained by pressing the probe (indenter) against the measuring object with the software (triboscan) attached to the measuring device .
The nanoindenter device and measurement conditions are as follows.
<Apparatus and measurement conditions>
Device: Nanoindenter; Triboindenter manufactured by Hysitron Inc
Measurement method: single press-in method
Measuring temperature: 23℃
Pressing speed: about 1000 nm/sec
Pressing depth: about 800 nm
Probe: Diamond, Berkovich type (triangular cone type)
(6) Base material-adhesive layer gripping force
On the adhesive layer side of the adhesive tape described in the examples, the adhesive surface of the adhesive tape (manufactured by Nitto Denko Co., Ltd., No. 315) was pasted with a hand press roller. Then, a double-sided tape (manufactured by Nitto Denko Co., Ltd., No. 5000N) was attached to the substrate side of the adhesive tape described in the embodiment to form a short strip of 10 mm×70 mm. After that, a 2 mm thick SUS plate was attached to the other side of the double-sided tape to form a test body.
The adhesive tape of the obtained test body was peeled off by 180° at 50 mm/mm and then torn off.
As a result, when only the adhesive tape is peeled off, that is, when the anchoring failure does not occur, it is set as pass (in the table is ○), and when the adhesive layer and the adhesive tape are torn off together, the anchoring failure occurs. In case of situation, measure the peeling force at this time.
Furthermore, since the adhesive force when the adhesive tape is directly attached to the SUS board is 5 N/10 mm, the qualified product in the above test can be said to have a gripping force of 5 N/10 mm or more.
(7) Paste residue evaluation 1 (the relationship between the time from point A to point B and the remaining paste)
Laminate the adhesive tape on the entire surface of the 4-inch silicon mirror wafer (bare wafer, with orientation plane) with a hand roller, and place it at room temperature for 1 hour.
Set the wafer with the above adhesive tape on the heating plate set to the temperature of point B of each adhesive tape ±5℃ (set up in a way that the surface of the heating plate is in contact with the surface of the wafer without the adhesive tape), and heat 10 seconds ± 1 second.
After the wafer with the adhesive tape is taken out from the hot plate, the wafer with the adhesive tape is placed in such a way that the adhesive tape is naturally peeled off (the wafer is turned over with the adhesive tape face down), and the adhesive tape is removed. Furthermore, when the adhesive tape does not fall naturally and is not removed from the wafer, the adhesive tape is clamped and removed with tweezers in this state. Also, in Example 7, before the peeling operation, 10 mJ/cm of ultraviolet rays were irradiated2
The adhesive is cured by ultraviolet rays. In Comparative Example 4, before this operation, 500 mJ/cm of ultraviolet rays were irradiated2
The adhesive is cured by ultraviolet rays. The ultraviolet radiation is used "UM810" manufactured by Nitto Seiki Co., Ltd.
Use an optical microscope (manufactured by Olympus Optical, objective lens 5 magnification, eyepiece 10 magnification) to observe the center 1×1 mm surface of the mirror surface after removing the adhesive tape, and count the paste residue on the wafer surface (not bonded The number of roughly dotted (grainy) or amorphous images observed on the new wafer before the adhesive tape.
In the table, the number of remaining pastes is 0 to 500 as ⊚, 500 to 1000 as ○, 1000 to 5000 as △, and 5000 or more as x.
(8) Paste residue evaluation 2 (the relationship between the time of point B→point C and the residue of paste)
Laminate the adhesive tape on the entire surface of the 4-inch silicon mirror wafer (bare wafer, with orientation plane) with a hand roller, and place it at room temperature for 1 hour.
Set the wafer with the adhesive tape attached to the hot plate set to the temperature of each adhesive tape ±5℃ (set in a way that the plate surface of the heating plate is in contact with the wafer surface without the adhesive tape), and heat 210 ±10 seconds.
After the wafer with the adhesive tape is taken out from the hot plate, the wafer with the adhesive tape is placed in a way that the adhesive tape is naturally peeled off (the surface of the adhesive tape is the ground side while the wafer is turned over) to remove the adhesive tape. Furthermore, when the adhesive tape does not fall naturally and is not removed from the wafer, the adhesive tape is clamped and removed with tweezers in this state. Also, in Example 7, before the peeling operation, 10 mJ/cm of ultraviolet rays were irradiated2
The adhesive is cured by ultraviolet rays. In Comparative Example 4, before this operation, 500 mJ/cm of ultraviolet rays were irradiated2
The adhesive is cured by ultraviolet rays. The ultraviolet radiation is used "UM810" manufactured by Nitto Seiki Co., Ltd.
Use an optical microscope (manufactured by Olympus Optical, objective lens 5 magnification, eyepiece 10 magnification) to observe the center 1×1 mm surface of the mirror surface after removing the adhesive tape, and count the paste residue on the wafer surface (not bonded The number of roughly dotted (grainy) or amorphous images observed on the new wafer before the adhesive tape.
In the table, the number of remaining pastes is 0 to 500 as ⊚, 500 to 1000 as ○, 1000 to 5000 as △, and 5000 or more as x.
[Production example 1] Production of thermally expandable microspheres A
150 g of sodium chloride, 20% by weight of colloidal silica (manufactured by Nissan Chemical Co., Ltd., brand name "SNOWTEX") 70 g of sodium chloride, 20% by weight of silica, 1 g of polyvinylpyrrolidone, and diethanolamine After 0.5 g of the condensate with adipic acid was added to 600 g of distilled water, the pH of the obtained mixture was adjusted to 2.8-3.2 to obtain an aqueous solution.
80 g of acrylonitrile, 40 g of methyl methacrylate, and 130 g of vinylidene chloride were added to the above-mentioned aqueous solution as oil-based additives for the material of the shell. Furthermore, 1 g of ethylene glycol dimethacrylate as a crosslinking agent was added to obtain a reaction solution.
The above-mentioned reaction solution is added to a pressure-resistant reaction vessel with a homomixer (manufactured by Teikoku Kogyo Co., Ltd., trade name "TK Homomixer"), and then isobutane (boiling point : -11.7° C.) 70 g and 5 g of the initiator (diisopropoxy dicarbonate) were added to the pressure-resistant reaction vessel.
After the homomixer was rotated under specific initial stirring conditions (stirring speed: 6000 rpm, stirring time: 2 minutes) to stir the above mixture, the mixture was stirred at 80 rpm and heated to 60°C for 24 hours of reaction. The solid content obtained by filtering the reaction solution after the reaction was placed at room temperature under a nitrogen stream for 1 week to obtain heat-expandable microspheres.
Furthermore, the obtained heat-expandable microspheres were measured with the trade name "SALD-2000J" manufactured by Shimadzu Corporation, and the average particle size was 12.5 μm. In addition, by X-ray CT (Xradia520versa manufactured by ZEISS Corporation (measurement conditions: tube voltage 60 KV, tube current 83 μA, pixel size 0.20 μm/pixel)), it is known that the solvent in the thermally expandable microspheres is isobutane. The weight of the heat-expandable microspheres contains 13% by weight. In addition, it was measured by the above-mentioned X-ray CT (computed tomography), and the thickness of the shell of the heat-expandable microsphere was 2.8 μm.
[Production Examples 2-11] Thermally expandable microspheres B～K
When preparing the aqueous solution, the amount of colloidal silica and the amount of oil additives (acrylonitrile, methacrylonitrile, isomethacrylate, methyl methacrylate, vinylidene chloride) are within the scope. The organic solvent (isobutane, isopentane (boiling point: 27.7°C), petroleum ether, isooctane (boiling point: 99°C)) enclosed in the shell, and the initial stirring conditions during polymerization are set as described in Table 1. Except for this, thermally expandable microspheres B to K were produced in the same manner as in Production Example 1. In addition, the average particle size of the thermally expandable microspheres, the amount of organic solvent contained, and the thickness of the shell were measured in the same manner as in Production Example 1. The results are shown in Table 1.
[Table 1] Manufacturing example 1 Manufacturing example 2 Manufacturing example 3 Manufacturing example 4 Manufacturing example 5 Manufacturing example 6 Manufacturing example 7 Manufacturing example 8 Manufacturing example 9 Manufacturing example 10 Manufacturing example 11
Thermally expandable microsphere A Thermally expandable microsphere B Thermally expandable microsphere C Thermally expandable microsphere D Thermally expandable microsphere E Thermally expandable microsphere F Thermally expandable microsphere G Thermally expandable microsphere H Thermally expandable microspheres I Thermally expandable microsphere J Thermally expandable microsphere K
Aqueous solution Distilled water (parts by weight) 600 600 600 600 600 600 600 600 600 600 600
Sodium chloride (parts by weight) 150 150 150 150 150 150 150 150 150 150 150
Colloidal silica (parts by weight) 70 70 70 70 70 70 70 40 40 40 70
Polyvinylpyrrolidone (parts by weight) 1 1 1 1 1 1 1 1 1 1 1
Diethanolamine/adipic acid condensate (parts by weight) 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5
Oil-based additives (shell forming materials) Acrylonitrile (parts by weight) 80 150 50 50 150 50 80 110 100 110 80
Methacrylonitrile (parts by weight) 0 0 100 130 80 50 0 55 60 0 0
Isomethacrylate (parts by weight) 0 0 0 0 10 0 0 0 0 0 0
Methyl methacrylate (parts by weight) 40 100 100 70 10 100 40 85 80 80 40
Vinylidene chloride (parts by weight) 130 0 0 0 0 0 130 0 0 0 130
Organic solvent (organic solvent contained in the shell) Addition of isobutane (parts by weight) 70 50 0 0 0 150 70 20 0 0 0
Addition of isopentane (parts by weight) 0 0 60 0 20 0 0 0 0 70 70
Addition of petroleum ether (parts by weight) 0 20 0 0 0 0 0 0 0 0 0
Isooctane addition amount (parts by weight) 0 0 0 60 40 0 0 80 70 0 0
Polymerization conditions Initial stirring speed (rpm) 6000 6000 8000 12000 12000 6000 60000 3500 2500 3500 6000
Initial mixing time (minutes) 2 3 2 2 2 3 2 2 2 2 2
Polymerization temperature (℃) 60 60 60 60 60 60 60 60 60 60 60
Polymerization time (hours) twenty four twenty four twenty four twenty four twenty four twenty four twenty four twenty four twenty four twenty four twenty four
characteristic Solvent content in heat-expandable microspheres (weight%) 13 19 twenty three 18 19 28 13 20 25 30 13
Average particle size (μm) 12.5 20 30 20 twenty three 35 12.5 30 38 34 12.5
Shell thickness (μm) 2.8 2.1 2.5 3 2.5 2 2.8 2.5 1.5 0.8 2.8
Tg of shell resin(℃) 86 99 108 110 104 105 86 104 105 99 86
[Example 1]
The acrylic copolymer (ethyl acrylate (EA), methyl methacrylate (MMA), 2-ethylhexyl acrylate (2EHA), and 2-hydroxyethyl acrylate (HEA) copolymer, EA structural unit : MMA structural unit: 2EHA structural unit: HEA structural unit = 60: 5: 30: 5 (weight ratio); weight average molecular weight: 350,000; hydroxyl value: 24) 100 parts by weight, adhesion imparting agent (manufactured by YASUHARA CHEMICAL, product Name "YS POLYSTAR S145") 20 parts by weight, isocyanate-based crosslinking agent (manufactured by TOSOH, trade name "Coronate L") 3 parts by weight, 30 parts by weight of thermally expandable microspheres A, and 210 parts by weight of toluene were mixed to prepare an adhesive Composition for formation of agent layer. In addition, the weight average molecular weight of the acrylic copolymer was measured by the method described in the above evaluation (1).
The composition for forming an adhesive layer was coated on a PET film (thickness: 50 μm) as a substrate and dried to obtain an adhesive tape (adhesive layer (thickness: 30 μm)/substrate). Furthermore, the gel fraction of the adhesive is 85%.
The obtained adhesive tape was used for the above evaluations (3) to (8). The results are shown in Table 2.
[Examples 2-7, Comparative Examples 1-4]
Except having made the composition of the acrylic copolymer and the composition of the composition for adhesive layer formation into the composition shown in Table 2, it carried out similarly to Example 1, and obtained the adhesive tape. The obtained adhesive tape was used for the above evaluations (3) to (8). The results are shown in Table 2. Furthermore, in Table 2, "crosslinking agent TETRAD C" is an epoxy crosslinking agent manufactured by MITSUBISHI GAS CHEMICAL (trade name "TETRAD C"), and "DPHA" is dipentaerythritol hexaacrylate (Shin Nakamura Chemical Co., Ltd. Company manufacture), "IRGACURE 184" is a photoinitiator manufactured by BASF Japan Co., Ltd. (trade name "IRGACURE 184").
[Table 2] Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Example 7
Adhesive Base polymer Monomer blending ratio Ethyl Acrylate (EA) 60 60 60 10
Methyl methacrylate (MMA) 5 5 5 5
Butyl Acrylate (BA) 90 90 85
2-Hydroxyethyl Acrylate (HEA) 5 5 5 5
2-ethylhexyl acrylate (2EHA) 30 90 30 30
Acrylic (AA) 5 5 10 5
Weight average molecular weight 350000 80000 700000 130000 350000 350000 600000
Hydroxyl value twenty four twenty four 0 0 twenty four twenty four twenty four
composition Base polymer (parts by weight) 100 100 100 100 100 100 100
Crosslinking agent Coronaate L (parts by weight) 3 3 1 5 5 3
Crosslinking agent TETRAD C (parts by weight) 0.5
Adhesive imparting agent YS POLYSTAR S145 (parts by weight) 20 30 20 20
DPHA (parts by weight) 100
IRGACURE 184 (parts by weight) 1
Adhesive gel fraction (weight%) 85 80 85 89 85 85 99
Heat-expandable microspheres type Thermally expandable microsphere A Thermally expandable microsphere B Thermally expandable microsphere C Thermally expandable microsphere D Thermally expandable microsphere E Thermally expandable microsphere F Thermally expandable microsphere G
Blending amount of heat-expandable microspheres (parts by weight) 30 25 30 50 25 50 30
Adhesive layer thickness (μm) 30 30 30 30 30 30 30
Substrate PET PET PET PET PET PET PET
Substrate thickness (μm) 50 50 50 50 50 50 50
Arithmetic average height of the adhesive layer when reaching point C Sa(μm) 12.3 17.2 19.8 16.5 17.6 21.8 6.8
Holding force between substrate/adhesive layer (N/20 mm) 〇 〇 〇 〇 〇 〇 〇
Adhesive layer nanoindenter elastic modulus (Mpa) 2.0 3.2 7.1 0.8 9.8 10.4 360
Thermomechanical analysis Time from point A to point B (seconds) 147 131 75 100 120 180 151
Time from point B to point C (seconds) 333 509 685 800 820 120 413
Temperature at point A (℃) 86 108 132 130 123 180 180
Temperature at point B (℃) 93 115 136 135 129 120 120
Temperature at point C (℃) 110 140 170 175 170 170 170
Evaluation of paste residue① ◎ ◎ 〇 ◎ ◎ ◎ ◎
Evaluation of paste residue ② ◎ ◎ ◎ ◎ ◎ △ ◎
Comparative example 1 Comparative example 2 Comparative example 3 Comparative example 4
Adhesive Base polymer Monomer blending ratio Ethyl Acrylate (EA) 60 10
Methyl methacrylate (MMA) 5 5
Butyl Acrylate (BA) 90 85
2-Hydroxyethyl Acrylate (HEA) 5
2-ethylhexyl acrylate (2EHA) 30 90
Acrylic (AA) 5 10 5
Weight average molecular weight 350000 700000 1300000 600000
Hydroxyl value twenty four 0 0 twenty four
composition Base polymer (parts by weight) 100 100 100 100
Crosslinking agent Coronaate L (parts by weight) 3 3 3 3
Crosslinking agent TETRAD C (parts by weight) 0.5 1
Adhesive imparting agent YS POLYSTAR S145 (parts by weight) 20
DPHA (parts by weight) 100
IRGACURE 184 (parts by weight) 1
Adhesive gel fraction (weight%) 85 95 80 ≧99.9
Heat-expandable microspheres type Thermally expandable microsphere H Hot knee swelling microsphere I Thermally expandable microsphere J Thermally expandable microsphere K
Blending amount of heat-expandable microspheres (parts by weight) 30 30 30 30
Adhesive layer thickness (μm) 30 30 30 30
Substrate PET PET PET PET
Substrate thickness (μm) 50 50 50 50
Arithmetic average height of the adhesive layer when reaching point C Sa(μm) 20.1 30.7 23.2 5.9
Holding force between substrate/adhesive layer (N/20 mm) 〇 〇 〇 〇
Adhesive layer nanoindenter elastic modulus (Mpa) 2.0 7.2 6.5 Above 1000 MPa
Thermomechanical analysis Time from point A to point B (seconds) 31 13 15 640
Time from point B to point C (seconds) 109 188 150 160
Temperature at point A (℃) 155 150 110 125
Temperature at point B (℃) 157 151 112 155
Temperature at point C (℃) 162 160 115 180
Evaluation of paste residue① X X X X
Evaluation of paste residue ② X X X X
