JP3824471B2 - Cube corner type retroreflective sheet and cube corner mold - Google Patents

Description

【０１５３】
参考例２５（単位再帰反射率係数Ｒ測定用金型Ｍ_１及び再帰反射シートＳ_１）
前記参考例１の方法で作成した、１０ｍｍ＊１０ｍｍのプリズム集合単位Ａ０を縦横１０個ずつ合計１００個用いて外形１００ｍｍ角の組合せ体を作成し、これを母型として電鋳法を２回繰り返して単位再帰反射率係数Ｒ測定用キューブコーナー金型Ｍ_１を作成した。
【０１５４】
次にこの金型Ｍ_１を用いて、厚さ３００μｍのポリカーボネート系樹脂シート〔商品名「ユーピロンＥ３０００」；三菱エンジニアリングプラスティックス（株）製〕を成形温度２００℃、成形圧力５０ｋｇ／ｃｍ^２の条件で圧縮成形し、次いで加圧下で３０℃まで冷却した後に樹脂シートを取り出して、表面にキューブコーナープリズム層の厚さが２００μｍのキューブコーナー再帰反射素子が最密状に配置れたポリカーボネート樹脂製の単位再帰反射率係数Ｒ測定用のキューブコーナー再帰反射シートＳ_１を作成した。得られた再帰反射シートＳ_１を用い後記する単位再帰反射率係数Ｒの測定法に従って、プリズムのｘ方向（対をなす素子が共有する底辺の定める溝の方向）と測定器の垂直方向とがなす角度（プリズム方位角ω）０度、４５度、９０度及び１３５度における再帰反射率係数を測定し、金型構成単位Ａ_０に基づく密封封入単位のそれぞれのプリズム方位角における単位再帰反射率係数Ｒとした。得られた単位再帰反射率係数Ｒの値を表２に示す。
【０１５５】
参考例２６（単位再帰反射率係数Ｒ測定用金型Ｍ_２及び再帰反射シートＳ_２）
参考例２５において、参考例１の方法で作成したプリズム集合単位Ａ_０を用いる代わりに、参考例５の方法で作成したプリズム集合単位Ｂ_０を用いる以外は参考例２５と同様にして単位再帰反射率係数Ｒ測定用の金型Ｍ_２及び再帰反射シートＳ_２を作成し、以下参考例２５と同様にして再帰反射シートＳ_２のプリズム方位角０度、４５度、９０度及び１３５度における再帰反射率係数を測定し、金型構成単位Ｂ_０に基づく密封封入単位のそれぞれのプリズム方位角における単位再帰反射率係数Ｒとした。得られた単位再帰反射率係数Ｒの値を表２に示す。
【０１５６】
参考例２７（単位再帰反射率係数Ｒ測定用金型Ｍ_３及び再帰反射シートＳ_３）
参考例２５において、参考例１の方法で作成したプリズム集合単位Ａ０を用いる代わりに、参考例９の方法で作成したプリズム集合単位Ｃ０を用いる以外は参考例２５と同様にして単位再帰反射率係数Ｒ測定用の金型Ｍ_３及び再帰反射シートＳ_３を作成し、以下参考例２５と同様にして再帰反射シートＳ_３のプリズム方位角０度、４５度、９０度及び１３５度における再帰反射率係数を測定し、金型構成単位Ｃ_０に基づく密封封入単位のそれぞれのプリズム方位角における単位再帰反射率係数Ｒとした。得られた単位再帰反射率係数Ｒの値を表２に示す。
【０１５７】
参考例２８（単位再帰反射率係数Ｒ測定用金型Ｍ_４及び再帰反射シートＳ_４）
参考例２５において、参考例１の方法で作成したプリズム集合単位Ａ０を用いる代わりに、参考例１３の方法で作成したプリズム集合単位Ｄ０を用いる以外は参考例２５と同様にして単位再帰反射率係数Ｒ測定用の金型Ｍ_４及び再帰反射シートＳ_４を作成し、以下参考例２５と同様にして再帰反射シートＳ_４のプリズム方位角０度、４５度、９０度及び１３５度における再帰反射率係数を測定し、金型構成単位Ｄ_０に基づく密封封入単位のそれぞれのプリズム方位角における単位再帰反射率係数Ｒとした。得られた単位再帰反射率係数Ｒの値を表２に示す。
【０１５８】
参考例２９（単位再帰反射率係数Ｒ測定用金型Ｍ_５及び再帰反射シートＳ_５）
参考例２５において、参考例１の方法で作成したプリズム集合単位Ａ０を用いる代わりに、参考例１７の方法で作成したプリズム集合単位Ｅ０を用いる以外は参考例２５と同様にして単位再帰反射率係数Ｒ測定用の金型Ｍ_５及び再帰反射シートＳ_５を作成し、以下参考例２５と同様にして再帰反射シートＳ_５のプリズム方位角０度における再帰反射率係数を測定し、金型構成単位Ｅ_０に基づく密封封入単位の単位再帰反射率係数Ｒとした。得られた単位再帰反射率係数Ｒの値を表２に示す。
【０１５９】
参考例３０（単位再帰反射率係数Ｒ測定用金型Ｍ_６及び再帰反射シートＳ_６）
参考例２５において、参考例１の方法で作成したプリズム集合単位Ａ０を用いる代わりに、参考例１８の方法で作成したプリズム集合単位Ｆ０を用いる以外は参考例２５と同様にして単位再帰反射率係数Ｒ測定用の金型Ｍ_６及び再帰反射シートＳ_６を作成し、以下参考例２５と同様にして再帰反射シートＳ_６のプリズム方位角０度における再帰反射率係数を測定し、金型構成単位Ｆ_０に基づく密封封入単位の単位再帰反射率係数Ｒとした。得られた単位再帰反射率係数Ｒの値を表２に示す。
【０１６０】
参考例３１（単位再帰反射率係数Ｒ測定用金型Ｍ_７及び再帰反射シートＳ_７）
参考例２５において、参考例１の方法で作成したプリズム集合単位Ａ０を用いる代わりに、参考例１９の方法で作成したプリズム集合単位Ｇ０を用いる以外は参考例２５と同様にして単位再帰反射率係数Ｒ測定用の金型Ｍ_７及び再帰反射シートＳ_７を作成し、以下参考例２５と同様にして再帰反射シートＳ_７のプリズム方位角０度における再帰反射率係数を測定し、金型構成単位Ｇ_０に基づく密封封入単位の単位再帰反射率係数Ｒとした。得られた単位再帰反射率係数Ｒの値を表２に示す。
【０１６１】
参考例３２（単位再帰反射率係数Ｒ測定用金型Ｍ_８及び再帰反射シートＳ_８）
参考例２５において、参考例１の方法で作成したプリズム集合単位Ａ０を用いる代わりに、参考例２０の方法で作成したプリズム集合単位Ｈ０を用いる以外は参考例２５と同様にして単位再帰反射率係数Ｒ測定用の金型Ｍ_８及び再帰反射シートＳ_８を作成し、以下参考例２５と同様にして再帰反射シートＳ_８のプリズム方位角０度における再帰反射率係数を測定し、金型構成単位Ｈ_０に基づく密封封入単位の単位再帰反射率係数Ｒとした。得られた単位再帰反射率係数Ｒの値を表２に示す。
【０１６２】
参考例３３（単位再帰反射率係数Ｒ測定用金型Ｍ_９及び再帰反射シートＳ_９）
参考例２５において、参考例１の方法で作成したプリズム集合単位Ａ０を用いる代わりに、参考例２１の方法で作成したプリズム集合単位Ｊ０を用いる以外は参考例２５と同様にして単位再帰反射率係数Ｒ測定用の金型Ｍ_９及び再帰反射シートＳ_９を作成し、以下参考例２５と同様にして再帰反射シートＳ_９のプリズム方位角０度における再帰反射率係数を測定し、金型構成単位Ｊ_０に基づく密封封入単位の単位再帰反射率係数Ｒとした。得られた単位再帰反射率係数Ｒの値を表２に示す。
【０１６３】
【表２】

【０１６４】
【実施例１】
参考例２１において、参考例１の方法で作成した１０ｍｍ＊１０ｍｍのプリズム集合プリズム集合単位を縦横１０個ずつ合計１００個用いて外形１００ｍｍ角の組合せ体を作成する代わりに、前記の参考例１及び参考例１３で作成された５ｍｍ＊５ｍｍの金型構成単位Ａ_０及びＤ_０を交互に２つずつ組み合わせて、金型構成単位４個からなる、図１３に示すような外形１０ｍｍ角の最小繰り返し単位を形成し、この最小繰り返し単位をさらに縦、横１０単位ずつ合計１００単位組み合わせて外形１００ｍｍ角の組合せ体を作成する以外は参考例２１と同様にしてキューブコーナー金型を形成した。
この金型を用い以下参考例２１と同様にして表面にキューブコーナープリズム層の厚さが２００μｍのキューブコーナー型再帰反射素子が最密状に配置されたポリカーボネート樹脂製のキューブコーナー型再帰反射シートを作成した。得られた再帰反射シートの集合再帰反射率係数の測定及び外観の評価を後記する方法に従って行った。測定結果を表３に示す。
【０１６５】
【実施例２】
参考例５及び参考例９で作成された金型構成単位Ｂ_０及びＣ_０を組み合わせて金型構成単位４個からなる図１４に示すような外形１０ｍｍ角の最小繰り返し単位を形成する以外は実施例１と同様にしてキューブコーナー金型を形成した。
【０１６６】
以下参考例２１と同様にして、表面にキューブコーナープリズム層の厚さが２００μｍのキューブコーナー型再帰反射素子が最密状に配置されたポリカーボネー樹脂製のキューブコーナー型再帰反射シートを作成した。得られた再帰反射シートの集合再帰反射率係数の測定及び外観の評価を後記する方法に従って行った。
測定結果を表３に示す。
【０１６７】
【実施例３】
参考例１、参考例５及び参考例９で作成された金型構成単位Ａ_０、Ｂ_０及びＣ_０を組み合わせて、金型構成単位９個からなる図１５に示すような外形１５ｍｍ角の最小繰り返し単位を形成し、この最小繰り返し単位をさらに縦、横８単位ずつ合計６４単位組み合わせて外形１２０ｍｍ角の組合せ体を作成する以外は実施例１と同様にしてキューブコーナー金型を形成した。
【０１６８】
以下参考例２１と同様にして、表面にキューブコーナープリズム層の厚さが２００μｍのキューブコーナー型再帰反射素子が最密状に配置されたポリカーボネー樹脂製のキューブコーナー型再帰反射シートを作成した。得られた再帰反射シートの集合再帰反射率係数の測定及び外観の評価を後記する方法に従って行った。
測定結果を表３に示す。
【０１６９】
【実施例４】
参考例１〜４及び参考例１３〜１６で作成された金型構成単位Ａ_０、Ａ_１、Ａ_２、Ａ_３、Ｄ_０、Ｄ_１、Ｄ_２及びＤ_３を組み合わせて、金型構成単位６４個からなる図１６に示すような外形４０ｍｍ角の最小繰り返し単位を形成し、この最小繰り返し単位をさらに縦、横３単位ずつ合計２５単位組み合わせて外形１２０ｍｍ角の組合せ体を作成する以外は実施例１と同様にしてキューブコーナー金型を形成した。
【０１７０】
以下参考例２１と同様にして、表面にキューブコーナープリズム層の厚さが２００μｍのキューブコーナー型再帰反射素子が最密状に配置されたポリカーボネー樹脂製のキューブコーナー型再帰反射シートを作成した。得られた再帰反射シートの集合再帰反射率係数の測定及び外観の評価を後記する方法に従って行った。
測定結果を表３に示す。
【０１７１】
【実施例５】
参考例５〜１２で作成された金型構成単位Ｂ_０、Ｂ_１、Ｂ_２、Ｂ_３、Ｃ_０、Ｃ_１、Ｃ_２及びＣ_３を組み合わせて、金型構成単位６４個からなる図１７に示すような外形４０ｍｍ角の最小繰り返し単位を形成し、この最小繰り返し単位をさらに縦、横３単位ずつ合計２５単位組み合わせて外形１２０ｍｍ角の組合せ体を作成する以外は実施例１と同様にしてキューブコーナー金型を形成した。
【０１７２】
以下参考例２１と同様にして、表面にキューブコーナープリズム層の厚さが２００μｍのキューブコーナー型再帰反射素子が最密状に配置されたポリカーボネー樹脂製のキューブコーナー型再帰反射シートを作成した。得られた再帰反射シートの集合再帰反射率係数の測定及び外観の評価を後記する方法に従って行った。
測定結果を表３に示す。
【０１７３】
【実施例６】
参考例１９及び参考例２０で作成された金型構成単位Ｇ_０及びＨ_０を組み合わせて、金型構成単位４個からなる図１８に示すような外形１０ｍｍ角の最小繰り返し単位を形成する以外は実施例１と同様にしてキューブコーナー金型を形成した。
【０１７４】
以下参考例２１と同様にして、表面にキューブコーナープリズム層の厚さが２００μｍのキューブコーナー型再帰反射素子が最密状に配置されたポリカーボネー樹脂製のキューブコーナー型再帰反射シートを作成した。得られた再帰反射シートの集合再帰反射率係数の測定及び外観の評価を後記する方法に従って行った。
測定結果を表３に示す。
【０１７５】
【実施例７】
参考例５、参考例９、参考例１７及び参考例１８で作成された金型構成単位Ｂ_０、Ｃ_０、Ｅ_０及びＦ_０を組み合わせて、金型構成単位１６個からなる図１９に示すような外形２０ｍｍ角の最小繰り返し単位を形成し、この最小繰り返し単位をさらに縦、横５単位ずつ合計２５単位組み合わせて外形１００ｍｍ角の組合せ体を作成する以外は実施例１と同様にしてキューブコーナー金型を形成した。
【０１７６】
以下参考例２１と同様にして、表面にキューブコーナープリズム層の厚さが２００μｍのキューブコーナー型再帰反射素子が最密状に配置されたポリカーボネー樹脂製のキューブコーナー型再帰反射シートを作成した。得られた再帰反射シートの集合再帰反射率係数の測定及び外観の評価を後記する方法に従って行った。
測定結果を表３に示す。
【０１７７】
【実施例８】
参考例１及び参考例２１で作成された金型構成単位Ａ_０及びＪ_０を組み合わせて、金型構成単位４個からなる図２０に示すような外形１０ｍｍ角の最小繰り返し単位を形成する以外は実施例１と同様にしてキューブコーナー金型を形成した。
【０１７８】
以下参考例２１と同様にして、表面にキューブコーナープリズム層の厚さが２００μｍのキューブコーナー型再帰反射素子が最密状に配置されたポリカーボネー樹脂製のキューブコーナー型再帰反射シートを作成した。得られた再帰反射シートの集合再帰反射率係数の測定及び外観の評価を後記する方法に従って行った。
測定結果を表３に示す。
【０１７９】
【比較例１】
参考例１及び参考例３で作成された金型構成単位Ａ_０及びＡ_２を組み合わせて、金型構成単位４個からなる図２１に示すような外形１０ｍｍ角の最小繰り返し単位を形成する以外は実施例１と同様にしてキューブコーナー金型を形成した。
【０１８０】
以下参考例２１と同様にして、表面にキューブコーナープリズム層の厚さが２００μｍのキューブコーナー型再帰反射素子が最密状に配置されたポリカーボネー樹脂製のキューブコーナー型再帰反射シートを作成した。得られた再帰反射シートの集合再帰反射率係数の測定及び外観の評価を後記する方法に従って行った。
測定結果を表３に示す。
【０１８１】
【表３】

【０１８２】
なお、単位再帰反射率係数Ｒ及び集合再帰反射率係数の測定並びに外観の評価は、以下の方法により行った。
【０１８３】
単位再帰反射率係数Ｒ
再帰反射性能測定器として、アドバンスト・レトロ・テクノロジー社
（Ａｄｖａｎｃｅｄ Ｒｅｔｒｏ Ｔｅｃｈｎｏｌｏｇｙ，ＩＮＣ）製「モデル（ＭＯＤＥＬ）９２０」を用い、ＪＩＳ ｚ−９１１７に準じて、前記参考例２１〜２８の方法で作成した、それぞれ全て同一の密封封入単位からなる再帰反射シートＳ_１〜Ｓ_８について、これら参考例のそれぞれに記載したプリズム方位角の入射角５度、観測角０．２０度における再帰反射光量（ｃｄ／Ｌｘ・ｃｍ^２）を測定し、それぞれの密封封入単位のそれぞれのプリズム方位角における単位再帰反射率係数Ｒとした。
【０１８４】
次に、実施例１〜８及び比較例１それぞれにおいて、組み合わされる金型構成単位に基づいた密封封入単位の単位再帰反射率係数Ｒのうち、最大の値をＲ_ｍａｘとし最小の値をＲ_ｍｉｎとしてＲ_ｍｉｎ／Ｒ_ｍａｘの値を求め、また、相隣り合う密封封入単位又は密封封入単位のブロックの単位再帰反射率係数Ｒの比Ｒ_Ｌ／Ｒ_Ｈ（但しＲ_Ｌ≦Ｒ_Ｈ）のうち最小の値を求める。
【０１８５】
集合再帰反射率係数
上記の単位再帰反射率係数Ｒの測定に用いたのと同じ再帰反射性能測定器を用い、実施例１〜８及び比較例１で得られた１００ｍｍ＊１００ｍｍの再帰反射シートの再帰反射光量をＪＩＳ Ｚ−９１１７に準じて、プリズム方位角０度及び４５度の入射角５度及び３０度、観測角０．２０度及び１．０度における再帰反射光量（ｃｄ／Ｌ ｘ・ｃｍ^２）を測定し、これら実施例又は比較例の集合再帰反射率係数とした。
【０１８６】
外観の評価
実施例１〜８及び比較例１で得られた１００ｍｍ＊１００ｍｍの再帰反射シートについて、目視により外観の観察を行い、次の基準に従って評価した。
◎……金型構成単位間の輝度の差は全く目立たない。
○……金型構成単位間の輝度の差はほとんど目立たない。
△……金型構成単位間の輝度の差が僅かに見分けられる。
×……金型構成単位間の輝度の差がはっきりと見える。
【０１８７】
【発明の効果】
本発明は、基盤上にキューブコーナー型再帰反射素子が最密充填状に配置されたプリズム集合面と、該プリズム集合面を囲周する周壁とからなるプリズム集合単位を有する金型構成単位であって、該金型構成単位が、キューブコーナー型再帰反射素子の光学軸が傾斜している再帰反射素子、及び該再帰反射素子の少なくとも１つのプリズム頂角が９０度から僅かな偏差を有する再帰反射素子から選ばれるプリズム集合単位を有する金型構成単位を含む少なくとも２種類以上の相異なる特定の金型構成単位が組み合わされているキューブコーナー金型、並びに、この金型を用いて成形することのできるキューブコーナー型再帰反射シートにより、３つの広角性、すなわち、入射角特性、観測角特性及び回転角特性を共に満足するとともに、再帰反射シートの重要な商品価値の一つであるシート外観の意匠性の問題点、すなわちシートを近くから見たときにもプリズム集合面の区画が再帰反射シートの表面からかなりはっきりと見えてしまうなどの問題点を改善することができた。
【０１８８】
【図面の簡単な説明】
【図１】本発明のキューブコーナー金型の作成に用いられるプリズム集合単位の代表的な態様である、三角錐型プリズム集合単位を模式的に表す拡大斜視図である。
【図２】本発明のキューブコーナー型再帰反射シートを構成する密封封入単位の代表的な態様である、三角錐型プリズム集合面を有する密封封入単位の断面図である。
【図３】本発明のキューブコーナー金型のプリズム集合単位又はキューブコーナー型再帰反射シートの密封封入単位における周壁の頂部の形状を示す模式図である。
【図４】本発明の代表的な態様である、三角錐型キューブコーナー金型を構成するためのプリズム集合単位又は三角錐型キューブコーナー再帰反射シートの密封封入単位内の、プリズム集合面の拡大平面図である。
【図５】図４における一組の三角錐型キューブコーナー再帰反射素子対のさらなる拡大平面図である。
【図６】図５におけるＡ−Ａの線に沿って切断した三角錐型キューブコーナー再帰反射素子対の断面図である。
【図７】本発明の別の態様である、三角錐型キューブコーナー金型を構成するためのプリズム集合単位、又は三角錐キューブコーナー型再帰反射シートの密封封入単位内の、プリズム集合面の拡大平面図である。
【図８】図７における一組の三角錐型キューブコーナー再帰反射素子対のさらなる拡大平面図である。
【図９】図８における再帰反射素子対を切断線Ｂ−Ｂに沿って切断した三角錐型キューブコーナー再帰反射素子対の断面図である。
【図１０】Ｖ字状の溝底部の中心線について模式的に説明するための断面図（ａ）及び拡大平面図（ｂ）である。
【図１１】本発明のキューブコーナー型再帰反射シート又はキューブコーナー金型の最小繰り返し単位における、密封封入単位又は金型構成単位の配列を示す概念図である。
【図１２】本発明のキューブコーナー型再帰反射シート又はキューブコーナー金型の最小繰り返し単位において、密封封入単位のブロック又は金型構成単位４個ずつのブロックを形成している場合の密封封入単位又は金型構成単位の配列を示す概念図である。
【図１３】本発明の一実施態様である、実施例１における金型構成単位４個からなる最小繰り返し単位を表す概念図である。
【図１４】本発明の他の実施態様である、実施例２における金型構成単位４個からなる最小繰り返し単位を表す概念図である。
【図１５】本発明の他の実施態様である、実施例３における金型構成単位９個からなる最小繰り返し単位を表す概念図である。
【図１６】本発明の他の実施態様である、実施例４における金型構成単位６４個からなる最小繰り返し単位を表す概念図である。
【図１７】本発明の他の実施態様である、実施例５における金型構成単位６４個からなる最小繰り返し単位を表す概念図である。
【図１８】本発明の他の実施態様である、実施例６における金型構成単位４個からなる最小繰り返し単位を表す概念図である。
【図１９】本発明の他の実施態様である、実施例７における金型構成単位１６個からなる最小繰り返し単位を表す概念図である。
【図２０】本発明の他の実施態様である、実施例８における金型構成単位４個からなる最小繰り返し単位を表す概念図である。
【図２１】従来技術の実施態様である、比較例１における金型構成単位４個からなる最小繰り返し単位を表す概念図である。
【０１８９】
【符号の説明】
１……キューブコーナー型再帰反射素子
２……プリズム集合面
３……周壁
４……プリズム層
５……保持体層
６……結合剤層
７……空気層
８……表面層
９……支持体層
１０……接着剤層
１１……剥離材層
１２……Ｖ字状の溝
１３……Ｖ字状の溝の底部（１２）の平面又は曲面と、Ｖ字状の溝角を二等分する平面 とが交差することによって形成される直線
１４……Ｖ字状の溝の底部（１２）
ｃ_１，ｃ_２…共通の底辺を境にして互いに向い合う２つの再帰反射素子の、互いに向い合う側面
ａ_１，ａ_２，ｂ_１，ｂ_２…再帰反射素子の（ｃ_１，ｃ_２）以外の側面
Ｈ……再帰反射素子の頂部
Ｐ……再帰反射素子の頂部から底面に下された垂線と該底面との交点
Ｑ……再帰反射素子の光学軸と該底面との交点
ｐ……交点（Ｐ）から再帰反射素子対が共有する底辺までの距離
ｑ……交点（Ｑ）から再帰反射素子対が共有する底辺までの距離
Ｌ，Ｍ，Ｎ，…それぞれ相異なるキューブコーナー型再帰反射素子からなる密封封入単位、又はプリズム集合単位に基づく金型構成単位を表す。[0001]
[Industrial application fields]
The present invention relates to a cube-corner retroreflective sheet having a novel structure in which prism-type retroreflective elements are arranged in a close-packed manner, and a cube-corner mold for producing the cube-corner retroreflective sheet. For signs such as construction signs, license plates for vehicles such as automobiles and motorcycles, safety materials such as clothing and lifesaving equipment, markings for signs, etc., reflectors for visible light, laser light or infrared light reflective sensors, etc. Useful cube-corner retroreflective element (hereinafter, also simply referred to as retroreflective element or reflective element) having excellent wide-angle property, and cube-corner mold for producing the cube-corner retroreflective sheet About.
[0002]
More specifically, in the present invention, the light-transmitting prism layer has a light-incident side surface that is substantially smooth and has a light-transmitting holder layer, and a cube-corner retroreflective element on the back surface of the holder layer. A prism assembly surface arranged in a close-packed manner and a peripheral wall formed together with the retroreflection element that protrudes beyond the top of the retroreflection element and surrounds the prism assembly surface. A sealing layer comprising an air layer surrounded by a binder layer, wherein the top of the peripheral wall of the prism layer and the binder layer are connected to each other so that the peripheral wall, the prism assembly surface and the binder layer are surrounded by the binder layer. A cube-corner retroreflective sheet consisting of an assembly of enclosed units,A sealed enclosure unit having a prism assembly surface in which one kind of retroreflective elements are arranged in a close-packed manner in a sealed structure surrounded by a peripheral wall, the sealed enclosure unit comprising:A cube-corner retroreflective sheet in which at least two types are combined, wherein the cube-corner retroreflective sheet has a retroreflective element in which an optical axis of the reflective element is inclined with respect to a normal to the surface on the light incident side. And / or a retroreflective element in which at least one of the crossing angles (prism apex angles) formed by two of the three surfaces constituting the retroreflective element has a slight deviation from 90 degrees. It is related with the cube corner type retroreflection sheet | seat characterized by including the prism layer which becomes.
[0003]
Furthermore, the present invention provides a prism assembly surface in which cube-corner retroreflective elements projecting on one side of one base are arranged in a close-packed manner, and projects beyond the top of the retroreflective element from the base. A cube corner mold configured by combining a number of mold structural units each including a peripheral wall surrounding the prism assembly surface,A mold constituent unit having a prism assembly surface in which one type of retroreflective element is arranged in a close-packed manner in a peripheral wall, the mold constituent unit beingIn the cube corner mold that is combined with at least two kinds, the cube corner mold includes a retroreflective element in which an optical axis of the cube corner type retroreflective element is inclined with respect to a normal to the base of the retroreflective element. A prism assembly comprising a mold constituent unit and / or a retroreflective element in which at least one of the prism apex angles formed by two of the three surfaces constituting the retroreflective element has a slight deviation from 90 degrees. The present invention relates to a cube corner mold characterized by including a mold constituent unit having a unit.
[0004]
[Prior art]
Conventionally, a retroreflective sheet that reflects incident light toward a light source is well known, and the sheet using the retroreflective property is widely used in the fields of use as described above. Above all, the cube-corner retroreflective sheet using the retroreflective principle of the cube-corner retroreflective element has much better light retroreflective efficiency than the conventional retroreflective sheet using micro glass spheres. The application is expanding year by year due to the retroreflective performance.
[0005]
In general, the basic performance desired for a retroreflective sheet is high luminance, that is, high reflection luminance represented by the reflection luminance of light incident from the front of the sheet, and wide-angle characteristics. Three performances are required: angular characteristics, incident angle characteristics, and rotational angle characteristics.
[0006]
Speaking of the high reflection luminance, it is usually said that the retroreflective luminance from the front of the cube corner type retroreflective sheet is two to three times higher than that of the micro glass sphere type retroreflective sheet. . This is because of the optical imperfection of the glass spheres commonly used in the latter micro glass sphere type retroreflective sheeting, as a lens element, and the low reflectance of the metal reflective side surface installed on the spherical side or the reflective side surface. Further, the retroreflective efficiency is likely to decrease due to the low ratio (about 70%) of the glass sphere to the entire surface on the light incident side, whereas the cube corner type retroreflective element used in the former is used. In this case, it is said that an optical element with relatively high accuracy can be formed, and light can be retroreflected over almost the entire surface of the retroreflective element.
[0007]
The first desired performance in terms of wide angle is observation angle characteristics. When the retroreflective sheet is used for various signs such as traffic signs, for example, since the position of the light source and the observer is not usually the same, the position is away from the incident optical axis that is the axis connecting the light source and the reflection point. It is necessary for sufficiently strong light to reach an observer. For this purpose, even if the observation angle, that is, the angle formed by the incident optical axis and the axis connecting the observer and the reflection point (observation axis) is increased, it is necessary that the decrease in reflected luminance is small.
[0008]
The reflected light has a slight angle (divergence angle) so that the bundle of light reflected by the retroreflective sheet has a certain extent and reaches the observer at a position off the incident optical axis. Need to be designed to spread. In terms of the relative position of the headlight and the driver in a transportation means such as a large truck, the observation angle is usually about 2 degrees at the maximum, so the divergence angle is controlled at an angle slightly exceeding this maximum observation angle. Should be.
[0009]
The second desired performance in terms of wide angle is incident angle characteristics. For example, when an automobile is approaching a traffic sign, the incident angle of the light of the headlight emitted from the automobile with respect to the sign, that is, the angle formed by the normal of the retroreflective sheet surface and the incident light, gradually increases. Accordingly, the intensity of light reaching the driver who is an observer decreases. In order for the sign to maintain sufficient reflection intensity even when the driver approaches the sign, excellent incident angle characteristics are required.
[0010]
As described above, the retroreflective efficiency decreases as the incident angle increases. In order to satisfy the three-surface reflection principle, which is the retroreflective principle of a cube-corner retroreflective element, the incident angle is relatively close to 0 degrees, that is, light is incident at an angle close to the retroreflective sheet surface. When the incident angle increases, the light does not reach the second or third reflection side surface to be reflected next, and the light escapes out of the element, thereby reducing the efficiency of retroreflection. Because. Further, as the incident angle increases, the internal total reflection condition is not satisfied, and light is transmitted through the reflection side surface of the element.
[0011]
A third desired performance with respect to wide angle is rotation angle characteristics. As a phenomenon peculiar to the cube-corner type retroreflective element, there is a property that the retroreflective luminance changes depending on from which direction of the retroreflective sheet the light enters. For this reason, when a retroreflective sheet is affixed to a sign, there is a complicated problem that the sheet must be affixed in a certain direction. The rotation angle characteristic is noticeably generated particularly in the case of a triangular pyramid reflection element. In the micro glass sphere type retroreflective sheet, this problem does not occur because the reflecting element has a rotating body shape.
[0012]
Thus, the cube corner type retroreflective sheet, particularly the triangular pyramid cube corner type retroreflective sheet, has many problems as described above, together with the excellent feature that the front luminance is extremely high. In order to solve these problems, many proposals have been known for a long time, and various improvements have been studied.
[0013]
For example, U.S. Pat. No. 2,481,757 of Jungersen discloses a retroreflective sheet in which various shapes of retroreflective elements are installed on a thin sheet, and a method of manufacturing the sheet. ing. The triangular-pyramidal reflective element exemplified in the above-mentioned U.S. Patent has a triangular pyramid-shaped reflective element whose apex is located on a perpendicular to the bottom plane passing through the center of the bottom triangle and the apex position is perpendicular to the vertical pyramid-shaped reflective element. An inclined triangular pyramid reflecting element that is not located on the line is illustrated, and it is described that such an inclined triangular pyramid reflecting element efficiently reflects light toward an approaching automobile. .
[0014]
However, the above-mentioned Jungersen U.S. Patent Specification describes, for example, what size and optical axis inclination the triangular pyramid-shaped reflective element needs to have in order to provide excellent observation angle characteristics and incident angle characteristics. There is no description or suggestion.
[0015]
In addition, Japanese Laid-Open Patent Application No. 60-100103 (U.S. Pat. No. 4,588,258) by Hopeman discloses an inclined triangular pyramid shape in which the shape of the triangle on the bottom is an isosceles triangle on a thin sheet. A retroreflective sheet is described in which cube-corner retroreflective elements are arranged so that their bottom surfaces are in close-packed form on a common surface. The optical axis of the triangular pyramidal cube-corner retroreflective element described in this patent specification is inclined in the opposite direction to the retroreflective element shown in the drawing of the above-mentioned Jungersen U.S. Patent Specification. The angle is shown to be about 7 degrees to 13 degrees.
[0016]
In the present specification, in order to clearly indicate the inclination direction of the optical axis of the triangular pyramid cube corner retroreflective element, it is expressed as “plus (+)” inclination and “minus (−)” inclination as follows. .
[0017]
That is, the triangular-pyramidal cube-corner retroreflective element is a retroreflective element pair sharing one base, and the common element pair is shared from the intersection (Q) between the optical axis of the retroreflective element and the bottom surface. Let q be the distance from the top (H) of the retroreflective element to the bottom surface, including the bottom, and the plane perpendicular to the bottom surface. When the distance from the base to the surface perpendicular to the bottom surface is p, the optical axis of the retroreflective element is inclined in a direction in which the difference (qp) between these distances becomes plus (+). When it is tilted, it is expressed as “plus (+)” slope, and when it is tilted in a direction in which this difference becomes minus (−), it is expressed as “minus (−)” slope.
[0018]
Incidentally, the inclined triangular pyramidal cube corner retroreflective element disclosed in the drawing of the Jungersen US patent specification is a positive inclination, and the inclined triangular pyramidal cube corner retroreflective element disclosed in the above-mentioned publication by Hopman. Is a negative slope.
[0019]
However, the above-mentioned conventionally known Jungersen U.S. Pat. No. 2,481,757; the triangular pyramidal cube corner retroreflective sheet such as the publication by Hopman, all of the prism assembly surface as in the present invention The cube corner retroreflective element described in these specifications or publications does not have a peripheral wall protruding from the side and surrounding the prism assembly surface. The triangular pyramid-shaped reflective element is common in that the bottom surface is on the same plane, but the incident angle characteristics are not sufficient, that is, when the incident angle of light with respect to the triangular pyramid-shaped reflective element increases, the retroreflective brightness Has not overcome the shortcoming of drastically decreasing. Further, these specifications or publications do not disclose any improvement in the observation angle characteristics and the rotation angle characteristics, and any retroreflective sheet that is considered to have been created based on these specifications or publications, However, these properties, particularly the rotation angle characteristics, are poor.
[0020]
As an attempt to improve the observation angle characteristics, for example, in Japanese Patent Application Laid-Open No. 63-143502 (U.S. Pat. No. 4,775,219) by Appeldon et al. When creating a triangular pyramid cube corner mold by cutting from three directions and forming a V-shaped groove intersecting at one point, the center line of the V-shaped groove is slightly inclined from the direction perpendicular to the flat plate. In addition, by cutting a plurality of types of V-shaped grooves by slightly changing the cutting angle from a normal value, a large number of types of triangular pyramid retroreflective elements with prism apex angles deviating slightly from 90 degrees are obtained. An attempt is made to form and give a certain extent to the reflected light of the cube-corner retroreflective sheet formed by this mold.
[0021]
The retroreflective sheet obtained by the method proposed by Appellorn et al. Can surely improve the incident angle characteristic and the observation angle characteristic to some extent, but it is very complicated operation with extremely high precision and skill to make the mold. The rotation angle characteristics cannot be expected to be improved by this method.
[0022]
Attempts to improve rotational angle characteristics include, for example, US Pat. No. 4,202,600 by Burke et al. And US Pat. No. 4,243,618 by Van Arnam et al. As disclosed, a method is known in which a prism assembly surface is divided into fixed sections, and the direction of the prism type retroreflective element on the prism assembly surface is changed for each section. These specifications also disclose an embodiment in which this section is divided into one or more sealed enclosure units by a peripheral wall, as in the present invention.
[0023]
According to this method, the rotation angle incident on the retroreflective element varies from unit to unit, and the reflected luminance changes accordingly. Therefore, when viewed from a long distance, the rotation angle characteristics are uniformed, Therefore, when this sheet is viewed, the section of the prism assembly surface can be seen quite clearly from the surface of the retroreflective sheet, and the design of the appearance of the sheet is lowered.
[0024]
Further, the retroreflective elements specifically disclosed in the US patent specifications by Burke et al. And Van Arnam et al. Are only regular triangular pyramidal cube corner retroreflective elements having a regular triangle on the bottom surface and a right isosceles triangle on three sides. In such a retroreflective sheet using a prism, no improvement in incident angle characteristics and observation angle characteristics can be expected. And, as in the present invention, the retroreflective sheet is composed of at least two or more sealed enclosing units including a sealed enclosing unit composed of a retroreflective element having an inclined optical axis or a retroreflective element having a slight deviation in prism apex angle. There is no description or suggestion that the configuration significantly improves the incident angle characteristic and the observation angle characteristic as well as the rotation angle characteristic.
[0025]
Furthermore, as a well-known product, a retroreflective sheet composed of a triangular pyramid prism type retroreflective element whose optical axis is inclined in the plus direction, which is a combination of four regions with different azimuth angles, is available from Stimsonite Corporation, "Stimsonite Series. # 6200 ”and“ Stimsonite Series # 4000 ”have been sold since about 1980.
[0026]
Also, for example, US Pat. No. 5,706,132 by Nestgard et al. And US Pat. No. 5,898,523 by Smith et al. Have similar retroreflective sheets, namely: There is disclosed a retroreflective sheet comprising a plurality of triangular pyramid retroreflective element bands, wherein the retroreflective elements in these regions have azimuths of about 90 degrees different from each other. Among them, the former is intended to exhibit an excellent retroreflection characteristic with respect to a high incident angle in two orthogonal directions. Specifically, the optical axis is about 7 in the minus (−) direction. It is a retroreflective sheet in which strip-shaped retroreflective element regions having a width of about 3 to 25 mm, which are composed of a group of triangular pyramidal retroreflective elements inclined at -15 degrees and whose azimuth angles are substantially orthogonal to each other, are alternately arranged, The objective is to exhibit excellent retroreflective properties with respect to a high incident angle regardless of the rotation direction of the retroreflective sheet. Specifically, the optical axis is about 12 to + (+) direction. This is a retroreflective sheet in which strip-shaped retroreflective element regions having azimuth angles substantially orthogonal to each other, which are composed of a group of triangular pyramid retroreflective elements inclined at 30 degrees, are alternately arranged.
[0027]
However, the retroreflective element region of the known product and the retroreflective element region specifically disclosed in the US patent specification by Nestgard et al. And Smith et al. Enclose the prism assembly surface of the retroreflective element as in the present invention. The cube-corner retroreflective sheet and cube of the present invention formed by combining two or more different units with a prism assembly surface and a peripheral wall surrounding the prism as one unit instead of having a surrounding wall The corner mold is clearly different in its structure. Similarly to the retroreflective sheets disclosed in the US patent specifications by Burke et al. And Van Arnam et al., When these retroreflective sheets are viewed from close, the difference in appearance between different retroreflective element regions can be clearly seen. Therefore, there is a problem that the design of the appearance of the sheet is deteriorated.
[0028]
[Problems to be Solved by the Invention]
The inventors of the present invention have a retroreflective sheet that satisfies the above three wide-angle characteristics, that is, the incident angle characteristic, the observation angle characteristic, and the rotation angle characteristic.TheIn order to develop it, I have been conducting research using a method of analyzing by light tracing computer simulation. As a result, inside the sealed structure surrounded by the peripheral wallReA hermetically sealed unit having a prism assembly surface in which retroreflective elements are arranged in a close packed mannerTheA cube-corner retroreflective sheet composed of an assembly of a large number of hermetically sealed units combined with at least two types, and in particular, as this hermetically sealed unit, an optical axisButThese wide-angle properties are improved by a cube-corner retroreflective sheet composed of at least two sealed encapsulating units, including a sealed encapsulating unit composed of inclined retroreflective elements and retroreflective elements having a slight deviation in prism apex angle. It was found that the above problem can be solved, and a cube-corner retroreflective sheet was actually made on the basis of this knowledge to confirm that this knowledge was correct, and further research was continued to complete the present invention.
[0029]
[Means for achieving the object]
According to the present invention, the light-transmitting prism layer includes a light-transmitting surface that is substantially smooth and has a light-transmitting holder layer, and a cube-corner retroreflective element is closely packed on the back surface of the holder layer. And a peripheral wall formed together with the retroreflective element that protrudes beyond the top of the retroreflective element and surrounds the prism collective surface, and separates the air layer from the prism layer A sealed encapsulating unit comprising an air layer that is connected to the top of the peripheral wall of the prism layer and the binder layer so that the air layer is surrounded by the peripheral wall, the prism assembly surface, and the binder layer. A cube-corner retroreflective sheet comprising a plurality of different types of sealed enclosure units, wherein the cube corner retroreflective sheet is a cube corner-type retroreflective sheet composed of an assembly of The retroreflective sheet has a prism layer made of a retroreflective element in which the optical axis of the reflective element is inclined with respect to a normal to the surface on the light incident side, and / or three surfaces constituting the retroreflective element There is provided a cube-corner retroreflective sheet comprising a prism layer comprising retroreflective elements in which at least one of the respective crossing angles (prism apex angles) formed by two of the surfaces has a slight deviation from 90 degrees. The
[0030]
According to the present invention, the cube corner mold used for producing the retroreflective sheet of the cube corner mold according to the present invention, that is, the cube corner type retroreflective element protruding on one side of one base is the closest packed. It is configured by combining a large number of mold constituent units each composed of a prism assembly surface arranged in a filling manner and a peripheral wall that protrudes beyond the top of the retroreflective element from the base and surrounds the prism assembly surface. A cube corner mold in which at least two different types of mold constituent units are combined. In the cube corner mold, the optical axis of the cube corner type retroreflective element is the retroreflective element. A mold constituent unit having a retroreflective element inclined with respect to a normal to the base of the element and / or 3 constituting the retroreflective element A cube corner mold comprising a mold constituent unit having a prism assembly unit composed of retroreflective elements in which at least one of the prism apex angles formed by two of the prisms has a slight deviation from 90 degrees Provided.
[0031]
Hereinafter, the present invention will be described in detail with reference to the drawings.
[0032]
FIG. 1 is an enlarged perspective view schematically showing a triangular pyramid prism assembly unit, which is a typical embodiment of a prism assembly unit used for creating a cube corner mold of the present invention. (1) is a cube-corner retroreflective element, and (2) is a prism assembly surface in which such retroreflective elements (1) are arranged in a close-packed manner. (3) is a peripheral wall surrounding the prism assembly surface (2), and protrudes beyond the top of the retroreflective element (1). In general, the shapes of the retroreflective elements (1) on the prism assembly surface are all substantially the same, but are not necessarily limited to this, and differ depending on the method of creating the prism assembly unit, as will be described later. A retroreflective element may be included.
[0033]
FIG. 2 is a cross-sectional view of a hermetically sealed unit having a triangular pyramid prism assembly surface, which is a typical embodiment of the hermetically sealed unit constituting the cube-corner retroreflective sheet of the present invention. (1) is a cube-corner retroreflective element, and (2) is a prism assembly surface in which such retroreflective elements (1) are arranged in a close-packed manner. (3) is a peripheral wall surrounding the prism assembly surface (2), protrudes beyond the top of the retroreflective element (1), and the top of the peripheral wall is joined to the binder layer (6), A sealing structure surrounded by the peripheral wall (3), the prism assembly surface (2) and the binder layer (6) and including an air layer (7) between the prism assembly surface (2) and the binder layer (6). Form.
[0034]
The retroreflective element (1) arranged in a close-packed manner to form the prism assembly surface (2) also forms a prism layer (4) with a peripheral wall (3) surrounding the prism assembly surface (2). The holding layer (5) is formed adjacent to the light incident side of the prism layer (4), and the light incident side surface of the holding layer (5) is substantially smooth. The prism layer (4) and the support layer (5) are usually integrated, and a sheet of a light transmitting material such as a synthetic resin is heated and embossed using the cube corner mold of the present invention. And the like.
[0035]
If necessary, the prism layer (4) and the holder layer (5) are provided on the surface on the light incident side of the holder layer (5) by physical or chemical means such as contamination, scratches, deterioration due to light or heat. A surface layer (8) made of a light transmissive material can be provided for the purpose of protecting against mechanical damage. The back surface of the binder layer (6) (the surface opposite to the light incident side) is usually a support layer (for the purpose of improving the strength and maintaining the shape of the binder layer (6) and the entire retroreflective sheet). 9) is provided, and on the back side, when using the retroreflective sheet, a pressure sensitive adhesive or a heat sensitive adhesive is used to adhere to an object such as a metal plate, a wooden plate, a glass plate, or a plastic plate. An adhesive layer (10) is formed. A release material layer (11) is stuck on the outer surface of the adhesive layer (10) in order to protect the surface of the adhesive layer (10) until it is stuck on the object.
[0036]
The light transmittance of the prism layer (4), the holding layer (5) and the surface layer (8) is generally 20% or more, preferably 50% or more.
[0037]
The material constituting the prism layer (4) and the holding layer (5) is not particularly limited, but those having optical transparency and uniformity are preferable, for example, polycarbonate resin, vinyl chloride resin. (Meth) acrylic resin, epoxy resin, styrene resin, polyester resin, fluororesin, olefin resin such as polyethylene resin and polypropylene resin, cellulosic resin and urethane resin. In the prism layer (4) and the support layer (5), an ultraviolet absorber, a light stabilizer, an antioxidant, and the like can be used alone or in combination for the purpose of improving the weather resistance. Further, various organic pigments, inorganic pigments and dyes, fluorescent dyes and the like can be contained as colorants.
[0038]
As the surface layer (8), the same resin as that used for the prism layer (4) and the holding layer (5) can be used. Similarly to the case of these layers, an ultraviolet absorber, a light stabilizer and Antioxidants and the like can be used alone or in combination. Furthermore, colorants such as various organic pigments, inorganic pigments, and dyes can be contained.
[0039]
Examples of the resin used for the binder layer (6) include (meth) acrylic resin, polyester resin, alkyd resin, epoxy resin, and the like. As a bonding method, a known heat-fusible resin bonding method or thermosetting resin is used. A bonding method, an ultraviolet curable resin bonding method, an electron beam curable resin bonding method, or the like can be appropriately employed.
[0040]
The binder layer (6) used in the present invention can be applied over the entire surface of the support layer (9), and can be selectively placed on the joining portion of the peripheral wall by a method such as printing.
[0041]
Examples of the material constituting the support layer (9) include a resin constituting the prism layer (4), a general film-formable resin, fiber, cloth, and a metal foil or plate such as stainless steel or aluminum. Or it can be used in combination.
[0042]
In the retroreflective sheet of the present invention, a printing layer is optionally provided between the surface layer (8) and the support layer (5), or on the surface layer (8) or the cube corner of the prism layer (4). It can be installed on the reflective side surface of the mold retroreflective element (1), and can usually be installed by means such as gravure printing, screen printing and inkjet printing.
[0043]
As can be seen from FIG. 2, FIG. 1 can also be viewed as an enlarged perspective view of the sealed encapsulating unit of FIG. 2 with the binder layer (6) removed as viewed from the prism assembly surface side. In this case, (1) is a cube-corner retroreflective element, and (2) is a prism assembly surface in which such retroreflective elements (1) are arranged in a close packed manner. (3) is a peripheral wall surrounding the prism assembly surface (2), and protrudes beyond the top of the retroreflective element (1).
[0044]
The cube-corner retroreflective element (1) on the prism assembly surface (2) in the prism assembly unit for constituting the cube corner mold or the sealed enclosure unit of the cube-corner retroreflective sheet is as described above. In addition to the triangular pyramid prism, a full cube prism, a tent prism, and the like may be used, but as the retroreflective element in the present invention, a triangular pyramid cube corner retroreflective element, a tent cube corner retroreflective element or A full cube retroreflective element is preferable, and a triangular pyramid cube corner retroreflective element is particularly preferable.
[0045]
Further, the shape of the prism assembly unit or hermetically sealed unit is not particularly limited as long as the same shape can be arranged in a close-packed form. For reasons such as a structure suitable for close packing, the shape is preferably an unequal triangle, isosceles triangle, right triangle, equilateral triangle, rectangle, square, rhombus, parallelogram, trapezoid, regular hexagon, etc. Particularly preferred are shapes such as right triangle, regular triangle, rectangle, square, rhombus and regular hexagon.
[0046]
The size of the prism assembly unit or the sealing enclosure unit is not particularly limited, but preferably 9 to 2500 mm.², More preferably 20 to 1000 mm²It is good to be in the range.
[0047]
If the size of the prism assembly unit or the sealed enclosure unit is not less than the above lower limit value, there will be no inconvenience such as an excessive increase in the area of the portion constituting the peripheral wall and a significant decrease in luminance, and the above upper limit. If the value is less than the value, it is difficult to cause inconveniences such as an excessive range where water or dust enters when the sealed enclosure structure is broken when the edge of the sheet is cut. The size is preferably within the above range.
[0048]
Furthermore, the size of the cube-corner retroreflective element in the prism assembly unit or hermetically sealed unit is 50 to 400 μm, preferably 60 to 200 μm, expressed as a height (h) from the reference plane. It is good. If the size of the retroreflective element is equal to or greater than the lower limit value, it is preferable because the divergence of reflected light due to the diffraction effect is excessive, and it is difficult to cause inconveniences such as a decrease in reflection performance. It is preferable because a flexible sheet can be obtained without becoming too thick.
[0049]
The term “reference plane” will be described in detail later.
[0050]
Furthermore, the thickness of the peripheral wall (3) in the prism assembly unit or hermetically sealed unit is in the range of 0.1 to 3 mm for reasons such as minimizing the area of the part that is not retroreflected and maintaining a beautiful appearance. It is preferable that it is in the range of 0.2 to 1 mm. The height of the peripheral wall (3) exceeds the height (h) of the top (H) of the cube-corner retroreflective element (1) and is preferably 1.5 times or less.
[0051]
Furthermore, the shape of the top of the peripheral wall (3) in the prism assembly unit or the sealing enclosure unit is flat, flat, or inclined as shown in FIG. 3 in order to improve adhesion to the binder layer, etc. It is preferably a combination of at least one shape selected from the group of curves consisting of a part of a circular arc and an ellipse, a hyperbola or a parabola.
[0052]
In the present specification, the “prism assembly unit” means a single-compartment unit composed of a prism assembly surface in which cube-corner retroreflective elements are arranged in a close-packed manner and a peripheral wall surrounding the prism assembly surface. As will be described later, it may be a convex primary prism collective matrix formed by directly cutting a smooth plate-like material, or the primary prism collective matrix alone, Or, the same primary prism aggregate master dies, or two or more different primary prism aggregate master dies are combined, and for example, a concave shape in which the shapes of these master vertices are reversed by a known method such as electroforming. Each of the convex secondary electroformed bodies formed by producing a primary electroformed body and then reversing the primary electroformed body by electroforming or the like is composed of a prism assembly surface and a peripheral wall. It may be a picture unit. The term “prism assembly unit” refers to such a primary prism assembly matrix or a cube corner mold formed by using the cube corner mold of the present invention, which is manufactured based on a primary or secondary electroformed body. It may be used for one division unit of the retroreflective sheet.
[0053]
In addition, as described above, the “mold constituent unit having a prism assembly unit” means that the “mold constituent unit” is a convex “prism assembly unit” by a known method such as electroforming. It is a concave shape formed by reversing the shape, and means a unit of section constituting a cube corner mold. However, the “mold constituent unit” is not necessarily limited to the one directly formed based on the “prism assembly unit”. For example, two different prism assemblies (convex shapes) having no peripheral wall are used. Formed by cutting the grooves that should become peripheral walls by reversal so that the resulting concave-shaped primary electroformed body is divided into units of a predetermined shape and size, by performing electroforming processing in an appropriate combination of seeds or more You can also
[0054]
FIG. 4 is a prism assembly surface in a prism assembly unit for constituting a triangular pyramid cube corner mold, or a sealed enclosure unit of a triangular pyramid cube corner retroreflective sheet, which is a representative embodiment of the present invention. 2) is an enlarged plan view of FIG. 5, FIG. 5 is a further enlarged plan view of the pair of triangular pyramidal cube-corner retroreflective element pairs in FIG. 4, and FIG. 6 is a sectional view of the retroreflective element pair in FIG. It is sectional drawing of the triangular pyramid-shaped cube corner retroreflection element pair (1) cut | disconnected along AA.
[0055]
In FIG. 4, the V-shaped groove in the upward direction (hereinafter referred to as the y direction for convenience) and the V-shaped groove in the downward direction (hereinafter referred to as the z direction for convenience) Are formed at the same pitch, and the triangular pyramid-shaped cube corner retroreflective element assembly includes a bottom center line of the V-shaped groove in the y direction and a bottom center line of the V-shaped groove in the z direction. The intersecting point passes through the center line of the bottom of the V-shaped groove in the vertical direction (hereinafter referred to as x-direction for convenience), that is, parallel V-shaped grooves in the three directions of x, y and z. Each bottom center line of the group is formed so as to intersect at one point, and these three V-shaped groove groups are formed at the same depth. In other words, each V-shaped groove bottom center line of these V-shaped groove groups is on the same V-shaped groove bottom plane.
[0056]
Hereinafter, for convenience of explaining the present invention, at least two parallel V-shaped groove groups having the same pitch in the two directions intersect each other at one point on the same plane. A mode in which an aggregate of triangular pyramidal cube corner retroreflective elements is formed is referred to as a “coplanar mode”, and a plane including the bottom center line of such a parallel V-shaped groove group is defined as: It is called “common plane (Ss)”.
[0057]
Referring further to FIG. 4, the bottom surface of the triangular pyramidal cube corner retroreflective element (1) in the same plane is substantially an equilateral triangle or an isosceles triangle, and the retroreflective element (1) An element pair is formed with each of the other retroreflective elements (1) sharing the base. As described above, in general, these retroreflective elements (1) have substantially the same shape. In this case, a rotationally symmetric shape rotated by 180 degrees around the midpoint of the common base. It is. Each triangular pyramidal cube-corner retroreflective element may be formed by three substantially right-angled triangle side faces, at least one of which may be a substantially right-angled isosceles triangle.
[0058]
Note that the crossing angle (prism apex angle) formed by two of the three surfaces of the triangular pyramid cube corner retroreflective element is normally approximately 90 degrees as described above, but the prism apex angle is from 90 degrees. By providing a slight deviation, the reflected light bundle can be diverged by a slight angle, thereby improving the observation angle characteristics. The value of the apex angle deviation is, for example, ± 0.001 ° to ± 0.2 °, preferably ± 0.002 ° to ± 0.15 °, particularly preferably ± 0.003 ° to ± 0.1 °. The range can be exemplified.
[0059]
5 and 6 are a plan view and a cross-sectional view in which a pair of retroreflective elements sharing one base of the retroreflective element group shown in FIG. 4 are further enlarged. In the retroreflective element pair shown in FIG. 5, side surfaces (c) facing each other of two retroreflective elements (1) facing each other while sharing one base.₁, C₂) Are triangles having substantially the same shape. The other side surface (a₁, B₁), (A₂, B₂) Are triangles having substantially the same shape, but when the base triangle is a regular triangle, these side triangles are also isosceles triangles.
[0060]
5 and 6, the retroreflective element pair shares one base on the common plane (the base formed by the V-shaped groove bottom center line in the x direction), and each of the other two bases (y , Z-direction V-shaped groove bottom center line is formed so that the base sides thereof are equal to each other, and the element pair is shared by the intersection (Q) between the optical axis of the retroreflective element and the bottom surface. The distance from the top (H) of the retroreflective element to the bottom and the intersection (P) between the perpendicular to the bottom and the bottom shared by the element pair (p) ), When the optical axis of the retroreflective element is not inclined with respect to the perpendicular, the point P and the point Q coincide with each other, and when the optical axis is inclined, these points are It exists as a different point. Accordingly, when the optical axis is not tilted, the difference (qp) between these distances is 0, and when the optical axis is tilted, the value of (qp) is plus or minus. 4 to 6, the optical axis is inclined by θ with respect to the perpendicular in the direction in which the value of (q−p) is positive. In the present invention, this inclination angle is in the range of 0.5 to 12 degrees, preferably in the range of 0.6 to 7.5 degrees.
[0061]
Also, in the embodiment shown in FIGS. 4 to 6, the center of the bottom of each of the x-, y-, and z-direction parallel V-shaped groove groups forming the prism assembly in the same prism assembly unit or hermetically sealed unit. All of the lines are on a common plane (Ss). In other words, each V-shaped groove bottom plane (S) in which each bottom center line of the parallel V-shaped groove group in the three directions of x, y, and z exists._x, S_y, S_z) Are the same common plane (Ss). As described above, the height (h) from the common plane (Ss) of the cube-corner retroreflective element in the prism assembly unit or the sealed enclosure unit is in the range of 50 to 400 μm, preferably 60 to 200 μm. .
[0062]
As described above, in the embodiment shown in FIGS. 4 to 6, the bottom center line of each of the parallel V-shaped groove groups in the x, y, and z directions in the same prism assembly unit or hermetically sealed unit is Are also on the common plane (Ss), but are not necessarily limited thereto. At least one of the three-directional V-shaped grooves forming the triangular pyramid prism type retroreflective element in one prism assembly unit or hermetically sealed unit. The V-shaped groove in one direction may be formed at a different depth from the V-shaped groove in the other direction. The depth of the V-shaped groove may be all different in the three directions of x, y, and z, or may be formed deeper or shallower in only one direction than in the other two directions. Among them, two adjacent triangular-pyramidal prism-type retroreflective elements share one base on the bottom surface (for example, the base formed by the bottom center line of the V-shaped groove in the x direction), and the other In the retroreflective element pairs arranged so that the two bottom sides (the bottom sides formed by the bottom center lines of the V-shaped grooves in the y and z directions) are equal to each other, a V-shape that forms the shared bottom side It is preferable that each V-shaped groove is formed so that the groove bottom center line is deeper or shallower than the V-shaped groove bottom center line forming the other two bottom sides.
[0063]
FIG. 7 shows another embodiment of the present invention, a prism assembly surface (2 in a prism assembly unit for constituting a triangular pyramid cube corner mold or a sealed enclosure unit of a triangular pyramid cube corner retroreflective sheet. 8 is an enlarged plan view of the pair of triangular pyramidal cube-corner retroreflective element pairs in FIG. 7, and FIG. 9 is a section line B along the retroreflective element pair in FIG. It is sectional drawing of the triangular pyramid cube corner retroreflection element pair (1) cut | disconnected along -B.
[0064]
In FIG. 7, the retroreflective element assembly is formed by intersecting x, y, and z sets of parallel V-shaped grooves having different directions at one point, as in FIG. The pitches of the V-shaped groove groups in the y and z directions are all set at equal intervals. The optical axis is inclined by θ with respect to the perpendicular in the direction in which the value of (q−p) is positive. However, the retroreflective element assembly in FIG. 7 differs from that in FIG. 4 so that the depth of the V-shaped groove group in the x direction is deeper than the depth of the V-shaped groove group in the y and z directions. Therefore, the bottom center line of the V-shaped groove group in the x direction and the bottom center line of the V-shaped groove group in the y and z directions do not exist on the same plane.
[0065]
When discussing the bottom triangle of the retroreflective element according to the present invention, the bottom center line of each V-shaped groove is broken and connected to each other by extending the bottom center line. It is assumed that the bottom centerline of the deepest V-shaped groove group exists in the bottom centerline or the extended bottom centerline that is regarded as a straight line (hereinafter referred to as the extended bottom centerline) and is not on the same plane. Projected onto a flat plane and treated as a projected straight line (hereinafter simply referred to as a projected straight line).
[0066]
Returning to the description of FIG. 7, since the pitches of the V-shaped groove groups in the y and z directions are all equal as described above, the bottom center line of the V-shaped groove group in the x direction and V in the y and z directions. The bottom triangle of the retroreflective element formed by the projected straight line of the extended bottom center line of the letter-shaped groove group has the base by the V-shaped groove group extended bottom center line in the y and z directions as in FIG. It is an equal isosceles triangle.
[0067]
8 and 9 show the retroreflective element pair in FIG. 7 further enlarged. In the retroreflective element pair shown in FIG. 8, two retroreflective elements (1) facing each other with a common base (a base formed by a V-shaped groove bottom center line in the x direction) as a boundary, Sides facing each other (c₁, C₂) Is a pentagonal shape with a right top and substantially the same shape, and when assuming a plane perpendicular to the bottom including the common base, these retroreflective elements (1) It has a substantially mirror-symmetrical relationship. The other side surface (a₁, B₁), (A₂, B₂) Are substantially the same shape with a quadrilateral shape with a top at a right angle. Further, as the V-shaped groove in the x direction is formed to be deeper than the V-shaped groove in the y and z directions, the side surface (a₁) And (b₁) And (a₂) And (b₂) And the end portion of the ridge line formed by intersecting with the V-shaped groove in the x direction is a very small quadrangular plane having almost no retroreflectivity (d₁) And (d₂) Is formed.
[0068]
The retroreflective elements in FIGS. 7 to 9 which are retroreflective elements in the present invention are different from those in FIGS. 4 to 6 as described above, and the depth of the V-shaped groove in the x direction is V in the y and z directions. The center line of the V-shaped groove bottom in the x direction that forms each side of the bottom surface of the retroreflective element is flat (S_x) And the V-shaped groove bottom centerlines in the y and z directions are respectively plane (S_y, S_z) On the plane (S_y) And plane (S_z) Are the same plane and constitute a common plane (Ss)._x) Are different planes (with respect to FIG. 6) below the common plane (Ss).
[0069]
In the present invention, as in the case of FIGS. 4 to 6, the height (h) from the common plane (Ss) of the cube-corner retroreflective element in the prism assembly unit or sealed enclosure unit is 50 to 400 μm, preferably Is preferably in the range of 60 to 200 μm.
[0070]
In general, when the optical axis is tilted in the plus direction, the opposite prism side surfaces of the pair of retroreflective elements (c₁C₂) Is the other prism side surface (a₁, B₁A₂, B₂7), the side surface of the prism (c) is made deeper by making the V-shaped groove in the x direction deeper than the V-shaped groove in the y and z directions as shown in FIGS.₁C₂) And the area of the prism side surface (a₁, B₁A₂, B₂), And the prism side surface (a₁, B₁, C₁A₂, B₂, C₂) And the probability of reflection on the three reflection side surfaces, that is, a decrease in retroreflection brightness can be suppressed.
[0071]
Conversely, if the optical axis is tilted in the negative direction, the opposite side surfaces of the retroreflective element pair (c₁C₂) Is the other prism side surface (a₁, B₁A₂, B₂), But by making the V-shaped groove in the x direction shallower than the V-shaped grooves in the y and z directions, the prism is opposite to that shown in FIGS. Side (c₁C₂) To reduce the area of the prism side surface (a₁, B₁A₂, B₂), And the prism side surface (a₁, B₁, C₁A₂, B₂, C₂) Can be eliminated, and a reduction in retroreflection luminance can be suppressed.
[0072]
In the present invention, a mold constituent unit or a sealing unit having a prism assembly unit composed of retroreflective elements whose optical axes are inclined, and a mold constituent unit having a prism assembly unit composed of retroreflective elements whose optical axes are not inclined Or a sealing enclosing unit, a mold constituent unit having a prism assembly unit made of retroreflective elements having a slight apex angle deviation, or a sealing enclosing unit, or a V-shape in at least one direction among three V-shaped grooves A mold constituent unit or a sealed enclosing unit having a prism assembly unit composed of retroreflective elements formed in a different depth from a V-shaped groove in the other direction, or two of these elements. Any one of a mold constituent unit or a sealed enclosure unit having a prism assembly unit composed of two or more retroreflective elements may be combined. , It is necessary that the optical axis contains as an essential component of the mold structure units or sealing sealed units having a prism set unit consisting of retroreflective elements having an inclined retroreflective elements and / or apex angle deviation. Otherwise, the obtained cube corner type retroreflective sheet is not preferable because the effect of improving the wide angle characteristic of the present invention is not exhibited.
[0073]
As described above, the inclination angle of the retroreflective element having an inclined optical axis that is preferably employed in the present invention is preferably 0.5 with respect to a perpendicular line extending from the top (H) to the bottom of the retroreflective element. It is in the range of degrees to 12 degrees, more preferably 0.6 degrees to 7.5 degrees. If the inclination angle is not less than the lower limit value, it is preferable because the incident angle characteristics of the obtained retroreflective sheet are excellent, and if it is not more than the upper limit value, the reflection luminance on the front surface of the retroreflective sheet may be too low. It is preferable because it is not present.
[0074]
FIG. 10 is a cross-sectional view (a) and an enlarged plan view (b) for schematically explaining the center line of the V-shaped groove bottom.
[0075]
In general, the V-shaped groove bottom is literally described as having a V-shaped pointed shape, but in actuality, like the cross-section of the V-shaped groove (10) in FIG. The bottom portion (12) is generally substantially flat or gently curved as shown here. This is due to the shape of the tip of the diamond cutter in the molding process of the master mold for molding the retroreflective sheet, and also due to wear of the mold caused by the repeated molding of the retroreflective sheet. This is caused by a device for improving the separation of the sheet forming die from the mold. In the present invention, therefore, terms such as “V-shaped groove bottom center line”, “V-shaped groove bottom center line”, and “V-shaped groove bottom center line” are used. The plane or curved surface of the bottom (12) of the letter-shaped groove intersects with the plane that bisects the V-shaped groove angle (indicated by vertical wavy lines in FIG. 10 (a)). It shall represent with the straight line (11) formed.
[0076]
Various known methods can be used as a method of creating the prism assembly unit used in the present invention.
[0077]
For example, when the cube corner type retroreflective element is a triangular pyramid prism type retroreflective element or a tent prism type retroreflective element, the surface of a smooth plate-like material is processed by a fly cutting method using a diamond tool or the like. It is obtained by cutting a V-shaped groove by a method. In the case of a tent prism type retroreflective element, it is obtained by cutting a 90-degree V-shaped groove in one direction in parallel at equal intervals. At this time, the optical axis can be inclined by cutting the V-shaped groove so that the center line of the groove is inclined.
[0078]
In the case of a triangular pyramid prism type retroreflective element having a regular bottom surface, a V-shaped groove symmetrical with respect to two directions at an intersection angle of 60 degrees (that is, a V-shaped groove whose center line is not inclined) After being cut in parallel at equal intervals, symmetrical V-shaped grooves in another direction are cut in parallel at equal intervals so as to bisect the obtuse angle side of the crossing angle. At this time, the angle of the V-shaped groove is about 70.5 degrees. Thus, the triangular pyramid prism type retroreflective elements formed by symmetrical V-shaped grooves have the same shape, and the optical axis is inclined when the crossing angle of the V-shaped grooves is 60 degrees. Not.
[0079]
In order to form a triangular pyramid prism type retroreflective element having an inclined optical axis, in the above V-shaped groove cutting, the crossing angle of the V-shaped grooves in the y direction and the z direction is made larger than 60 degrees, Or what is necessary is just to cut small. If the crossing angle of the V-shaped groove is larger than 60 degrees, a minus-tilt triangular pyramid prism type retroreflective element can be formed, and if it is reduced, a plus-tilt triangular pyramid prism type retroreflective element is formed. be able to. The angle of the V-shaped groove and the angle of the V-shaped groove for setting the angle of intersection of the top of the triangular pyramid prism to 90 degrees are determined in advance from the values of the inclination direction and the inclination angle of the optical axis. It can be obtained by calculation.
[0080]
In these triangular pyramid prism type retroreflective elements, the valley bottoms of the V-shaped grooves in the three directions are usually on the same plane, but if necessary, for example, in the case of a positively inclined triangular pyramid prism type retroreflective element The depth of the third V-shaped groove is made deeper than the depth of the other two-way V-shaped grooves (see Patent International Publication No. WO 98/03743), and the triangular-pyramidal prism type recursion with negative inclination is used. In the case of a reflective element, the depth of the third V-shaped groove is made shallower than the depths of the other two V-shaped grooves (Japanese Patent Laid-Open No. 11-149006), thereby further improving the incident angle. Properties can be imparted.
[0081]
Further, as a method of giving a slight deviation from 90 degrees to the crossing angle of the apex portion of the triangular pyramid prism type retroreflective element, in the above V-shaped groove cutting, Japanese Patent Laid-Open No. 63-143502 (US Pat. No. 4). , 775, 219), the center line of the V-shaped groove is slightly inclined (ie, an asymmetric V-shaped groove is formed) and / or the cutting angle is increased. A method of cutting a V-shaped groove by slightly changing from 90 degrees can be mentioned. By cutting with an asymmetrical V-shaped groove, a plurality of types of triangular pyramid prism type retroreflective elements are formed. According to the method described in Japanese Patent Laid-Open No. 63-143502, it is also possible to form many types of triangular pyramid prism type retroreflective elements by cutting the same direction with a plurality of types of V-shaped grooves. is there.
[0082]
As a method of forming a full cube prism type retroreflective element, for example, US Pat. No. 1,591,572, US Pat. No. 3,922,065 and US Pat. No. 2,029,375 are disclosed. As described in the document, a prism can be formed at the tip of a metal pin and a plurality of them are bundled to form a prism assembly surface (pin bundling method). Also, U.S. Pat. No. 1,591,572, U.S. Pat. No. 3,069,721, U.S. Pat. No. 4,073,568, International Patent Publication No. WO 97/04940 and International Patent Publication No. WO 97. No. 04939, a thin plate material having two planes parallel to each other is stacked, and a V-shaped groove is cut at a pitch equal to a direction perpendicular to the plate material. A continuous roof-type projection group having a corner of about 90 degrees was formed, and then the top of the roof-type projection group formed on each plate-shaped material was formed on the adjacent plate-shaped material. It is obtained by moving it so as to coincide with the bottom of the V-shaped groove. The optical axis can be tilted by cutting an asymmetric V-shaped groove at the time of cutting the V-shaped groove and changing the thickness of the plate-like material. As in the case of the triangular pyramid prism type retroreflective element, the prism apex angle is slightly deviated from 90 degrees by cutting the V-shaped groove by slightly changing the cutting angle from 90 degrees. (Plate method).
[0083]
Examples of the smooth plate-like material used to create the triangular pyramid prism type retroreflective element and the tent prism type retroreflective element and the thin plate material used to make the full cube prism type retroreflective element include Vickers hardness ( JIS Z-2244) is preferably 350 or more, particularly preferably 380 or more, and specific examples thereof include amorphous copper, electrodeposited nickel and the like. Examples of alloy materials include copper- A zinc alloy, a copper-tin-zinc alloy, a nickel-cobalt alloy, a nickel-zinc alloy, etc. can be mentioned.
[0084]
Further, as these plate-like materials, synthetic resin materials having a glass transition point of 150 ° C. or higher, particularly 200 ° C. or higher, and a Rockwell hardness (JIS Z-2245) of 70 or higher, particularly 75 or higher are preferably used. Specifically, for example, polyethylene terephthalate resin, polybutylene phthalate resin, polycarbonate resin, polymethyl methacrylate resin, polyimide resin, polyarylate resin, polyethersulfone resin, poly Examples include ether imide resins and cellulose triacetate resins.
[0085]
Creation of the plate-like material from the synthetic resin as described above can be performed by a normal resin molding method, for example, an extrusion molding method, a calender molding method, a solution casting method, and the like, and further heat treatment and stretching treatment as necessary. Etc. can be performed.
[0086]
The plane of the obtained plate-like material is subjected to a preliminary conductive treatment in order to facilitate the conductive treatment and / or the electroforming process when forming an electroformed mold from the prism assembly unit produced by the method of the present invention. be able to.
[0087]
Examples of the preliminary conductive treatment include vacuum deposition methods for depositing metals such as gold, silver, copper, aluminum, zinc, chromium, nickel, selenium, cathode sputtering methods using these metals, electroless plating methods using copper and nickel, etc. Is mentioned. Alternatively, conductive fine powder such as carbon black, organic metal salt, or the like may be blended in the synthetic resin so that the flat plate itself has conductivity.
[0088]
The cube corner mold of the present invention is a cube corner mold formed by combining a plurality of at least two different mold constituent units formed on the basis of the prism assembly unit thus created. The cube corner mold has a retroreflective element in which the optical axis of the cube corner type retroreflective element is inclined with respect to a normal to the bottom surface of the retroreflective element and / or three surfaces constituting the retroreflective element. A cube corner comprising a mold constituent unit formed on the basis of a prism assembly unit comprising at least one retroreflective element having a slight deviation from 90 degrees, at least one of the crossing angles formed by two surfaces of It is a mold.
[0089]
The prism assembly unit to be combined is not necessarily limited to prism assembly units made of the same type of cube-corner retroreflective elements, but may be combined with prism assembly units made of other types of cube-corner retroreflective elements as necessary. You can also.
[0090]
Here, the “same type” cube-corner retroreflective element refers to, for example, a triangular-pyramidal cube-corner retroreflective element, a full-cube corner, regardless of the inclination of the optical axis and the deviation of the crossing angle of the prism top. The type retroreflective element and the tent prism type retroreflective element are classified as one type.
[0091]
In addition, the cube corner mold of the present invention is not necessarily limited to the one formed by combining the mold structural units without gaps, and the obtained retroreflective sheet has, for example, ultraviolet light emission, fluorescent light emission, electric light display, etc. In order to provide an information transmission function other than retroreflective, units having no retroreflective element can be combined as necessary.
[0092]
As a method for combining the mold constituent units, for example, when only a prism assembly unit composed of a triangular pyramid cube corner retroreflective element is used, two or more types are separately formed on the plate-shaped material previously molded into the same shape by the above method. After forming a convex (male) prism assembly unit with different types of triangular pyramidal cube corner retroreflective elements, combine them to form the smallest repeating unit matrix that is the basis of the mold, A minimum repeating unit composed of a combination of concave (female) mold constituent units is created by a method such as electroforming, and this is further combined to form a triangular pyramid cube corner mold such as an endless belt. be able to. Also, each prism assembly unit is separately electroformed, and if necessary, for example, by means of fly cutting or the like, cut according to the appropriate shape, the direction and size of the retroreflective element, and separate gold These can also be combined by forming a mold unit.
[0093]
In the above method, the peripheral wall surrounding the prism assembly surface can be engraved at the same time when forming the triangular pyramid cube corner retroreflective element, but the minimum repeating unit matrix composed of a combination of convex prism assembly units. When electroforming is performed after forming a mold, a peripheral wall is engraved by means such as a fly-cutting method along each prism assembly surface of the electroplated body of the minimum repetitive unit matrix obtained, and this is electroplated. By casting, a convex third generation minimum repeating unit matrix can be obtained. In addition, when each of the prism assembly units is electroformed separately, the obtained prism assembly unit electroformed body is cut according to the appropriate shape, the direction and size of the retroreflective element as described above. Thereafter, a peripheral wall can be engraved along the outer periphery of each prism assembly surface, and these can be combined to form a minimum repeating unit.
[0094]
When using only the prism assembly unit composed of the full cube prism retroreflective element, first, the formed prism assembly surface is electroformed to form a concave prism assembly unit electroformed body, Can be used to form a minimum repeating unit, and then engrave a peripheral wall along each prism assembly surface. In addition, after forming the concave prism assembly unit electroformed body, as described above, after cutting according to the appropriate shape, direction and size of the retroreflective element as necessary, on the outer periphery of each prism assembly surface Peripheral walls can be engraved along and combined to form a minimum repeating unit.
[0095]
The electroforming process is described in detail in International Patent Publication No. WO97 / 15435, and the description here replaces the description relating to the electroforming process in the present invention.
[0096]
The concave mold component unit created from the convex prism assembly unit by electroforming is precisely cut and then, as described above, another metal with a different type of retroreflective element produced in the same manner as described above. In combination with the mold constituent unit, a concave second generation minimum repeating unit constituting the cube corner mold of the present invention can be obtained. In addition, a second-generation minimum repeating unit having a concave shape can be created directly from a convex minimum repeating unit matrix.
[0097]
The second generation minimum repeating unit can be used repeatedly as an electroforming master used to create a third generation minimum repeating unit. Accordingly, it is possible to create a number of minimum repeating units from one minimum repeating unit, and the plurality of minimum repeating units thus created are precisely cut and then cube corner-type recursion made of synthetic resin. The cube corner mold of the present invention can be obtained by combining and joining to the final mold size for forming the reflection sheet.
[0098]
As a joining method, a method of simply abutting the cut end faces or a method of welding the combined joint part by a method such as electron beam welding, YAG laser welding, carbon dioxide laser welding, or the like can be employed.
[0099]
The obtained cube corner mold of the present invention is used for molding a synthetic resin as a mold for molding a synthetic resin. As the synthetic resin molding method, compression molding or injection molding can be employed.
[0100]
Compression molding is performed by, for example, forming a thin-walled nickel electroformed mold, a synthetic resin sheet having a predetermined thickness, and a silicone rubber sheet having a thickness of about 5 mm as a cushioning material into a compression molding press heated to a predetermined temperature. After insertion, after preheating for 30 seconds under a pressure of 10-20% of the molding pressure, 180-250 ° C., 10-30 kg / cm²It can be carried out by heating and pressurizing for about 2 minutes under the condition. After that, it is possible to obtain a prism molded product by cooling to room temperature while releasing the pressure and releasing the pressure.
[0101]
Further, for example, an endless belt mold is produced by joining thin electroformed molds having a thickness of about 0.5 mm formed by the above method by the welding method, and the belt mold is composed of a heating roll and a cooling roll. After installing and rotating on a pair of rolls, supplying the melted synthetic resin in the form of a sheet to the belt mold on the heating roll and performing pressure molding with one or more silicone rolls It is possible to obtain a continuous sheet-like product by cooling to a temperature below the glass transition temperature on a cooling roll and peeling it off from the belt mold.
[0102]
The cube corner mold of the present invention and the cube corner type retroreflective sheet formed by the cube corner mold each include at least two types of prism aggregate units having prism aggregate surfaces having different prism azimuth angles of the cube corner type retroreflective element. It can be configured to include a mold constituent unit formed on the basis of, or a combination of at least two or more hermetically sealed units. By constituting in this way, a cube corner type retroreflective sheet having particularly excellent rotation angle characteristics can be obtained.
[0103]
In order to create such a cube corner mold, separate prism assembly units in which cube corner type retroreflective elements having different prism azimuth angles are preliminarily engraved may be combined. It is also possible to engrave elements and rotate them to combine them.
[0104]
Further, the cube corner mold of the present invention and the cube corner type retroreflective sheet formed by the cube corner mold each include at least two types of prism aggregate units each having prism aggregate surfaces having different sizes of the cube corner type retroreflective element. It can be configured to include a mold constituent unit formed on the basis of, or a combination of at least two or more hermetically sealed units. By comprising in this way, the cube corner type retroreflection sheet excellent in the balance between the front luminance and the observation angle characteristic can be obtained.
[0105]
The ratio of the largest and smallest cube-corner retroreflective elements in the above is h as the ratio of the height of the retroreflective elements, for reasons such as good filling properties when forming the prism._min/ H_max= 0.25 to 1.0, and particularly preferably in the range of 0.5 to 1.0.
[0106]
The cube-corner type retroreflective sheet of the present invention does not impair the design of the appearance of the sheet because the section of the prism assembly surface is clearly visible from the surface even when the retroreflective sheet is viewed from close. In addition, the maximum value R of the unit retroreflectance coefficient R of each prism assembly surface in the plurality of types of sealed enclosure units constituting the retroreflective sheet_maxAnd the minimum value R_minRatio R_min/ R_maxIs preferably adjusted to be 0.5 or more, and preferably 0.6 or more.
[0107]
One way to do this is as a ratio R of unit retroreflectance coefficients R between adjacent sealed enclosure units or blocks of sealed enclosure units._L/ R_H(However, R_L≦ R_H) Is preferably adjusted so as to be 0.6 or more. Here, the “block of sealed enclosure units” can be exemplified by a collection of 2 to 40 sealed enclosure units made of cube-corner retroreflective elements having the same shape. In the cube-corner retroreflective sheet of the present invention, it is preferable that the blocks of the adjacent hermetically sealed units are composed of different hermetically sealed units. Accordingly, the cube corner mold of the present invention for forming such a retroreflective sheet is similarly a mold constituent unit in which blocks of adjacent mold constituent units are formed based on different prism assembly units. It is preferable that it is comprised by these.
[0108]
The unit retroreflectance coefficient R of the prism assembly surface is measured by the method described in the examples described later.
[0109]
FIG. 11 is a conceptual diagram showing the arrangement of hermetically sealed units or mold constituent units in the minimum repeating unit of the cube corner retroreflective sheet or cube corner mold of the present invention, and FIG. When forming the block of the enclosing unit or the block of the mold constituent unit, the arrangement of the sealed enclosing unit or the mold constituent unit in the minimum repeating unit of the cube corner type retroreflective sheet or the cube corner mold of the present invention. FIG.
[0110]
11 and 12, L, M, N,... Each represent a sealed enclosing unit made up of different cube-corner retroreflective elements, or a mold constituent unit.
[0111]
【Example】
Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples.
[0112]
Reference Example 1 (Mold Unit A₀)
Using a diamond bit having a tip angle of 70.529 degrees on a 10 mm * 10 mm brass plate whose surface is cut flat, the repetition pitches in the x, y and z directions are all 169.706 μm. These three directions A V-shaped groove having a symmetrical cross-sectional shape is cut to a depth of about 80 μm by a fly cutting method so that the crossing angles of both are 60.000 degrees, and the reflecting element is formed on the brass plate. A convex prism assembly unit having a cube-corner retroreflective element group having a height of 80.000 μm was formed. The optical axis tilt angle of the retroreflective element in the obtained convex prism assembly unit was 0 degree, and the prism apex angle was 90.000 degrees.
[0113]
Using this brass prism assembly unit, a concave prism assembly having a thickness of 5 mm and made of nickel was prepared by electroforming.
[0114]
This nickel prism assembly was cut into 5 mm square in both vertical and horizontal dimensions by the fly-cut method. At this time, the prism azimuth angle of the retroreflective element was determined so that the x-shaped V-shaped groove forming the prism intersected with the lateral side forming the outer shape of the mold unit. Thereafter, the outer peripheral four sides of the prism assembly cut piece are cut by a fly cutting method into a rectangular shape having a width of 0.15 mm and a depth of 0.1 mm (1.25 times the height of the reflecting element) using a diamond bite. Mold component unit (A₀)created. Table 1 summarizes the factors of the obtained mold constituent units.
[0115]
Reference Example 2 (Mold Component Unit A₁)
In Reference Example 1, when the created concave prism assembly is cut into 5 mm squares in the vertical and horizontal external dimensions by fly-cut method, the X-shaped V-shaped grooves forming the prisms are the die structural unit external shapes. Instead of setting and cutting the prism azimuth angle of the retroreflective element so as to intersect at right angles with the horizontal side forming the horizontal direction, it is rotated 45 degrees clockwise from the position of this reference example 1 and 45 degrees with this horizontal side. The prism azimuth angle of the retroreflective element was determined so as to intersect at an angle of and cut. Hereinafter, in the same manner as in Reference Example 1, the mold structural unit (A₁)created. Table 1 summarizes the factors of the obtained mold constituent units.
[0116]
Reference Example 3 (Mold Component Unit A₂)
When a concave prism assembly produced in the same manner as in Reference Example 1 is cut into 5 mm squares in the vertical and horizontal outer dimensions by a fly-cut method, the V-shaped groove in the third direction forming the prism is gold. Instead of determining and cutting the prism azimuth angle of the retroreflective element so as to intersect at right angles to the lateral sides forming the mold structural unit outline, it is rotated 90 degrees clockwise from the position of this reference example 1 The prism azimuth angle of the retroreflective element was determined and cut so as to be parallel to the side. Hereinafter, in the same manner as in Reference Example 1, the mold structural unit (A₂)created. Table 1 summarizes the factors of the obtained mold constituent units.
[0117]
Reference Example 4 (Mold Component Unit A₃)
When a concave prism assembly prepared in the same manner as in Reference Example 1 is cut into 5 mm squares in the vertical and horizontal outer dimensions by a fly-cut method, the V-shaped groove in the x direction forming the prism is a mold. Instead of deciding and cutting the prism azimuth angle of the retroreflective element so as to intersect at right angles with the horizontal side forming the structural unit outline, the horizontal side The prism azimuth angle of the retroreflective element was determined so as to intersect at an angle of 45 degrees and cut. Hereinafter, in the same manner as in Reference Example 1, the mold structural unit (A₃)created. Table 1 summarizes the factors of the obtained mold constituent units.
[0118]
Reference Example 5 (Mold Component Unit B₀)
In Reference Example 1, using a diamond bite having a tip angle of 77.042 degrees in the y direction and z direction and 56.529 degrees in the x direction, the repetition pitch of the V-shaped grooves in the y direction and the z direction is 164. .181 μm, x-direction V-shaped groove repeat pitch is 191.09 μm, and y-direction and z-direction V-shaped groove crossing angle is 50.679 degrees, V-shape in y-direction and x-direction A cube-corner retroreflective element group having a reflective element height of 80.000 μm is provided on a brass plate in the same manner as in Reference Example 1 except that the crossing angle of the groove is 64.661 degrees. A convex prism assembly unit was formed.
[0119]
The optical axis tilt angle of the retroreflective element in the obtained convex prism assembly unit was +7000 degrees, and the prism apex angle was 90.000 degrees.
[0120]
Using the obtained brass prism assembly unit, the mold constituent unit (B₀)created. Table 1 summarizes the factors of the obtained mold constituent units.
[0121]
Reference example 6 (mold structural unit B₁)
Using a brass prism assembly unit prepared in the same manner as in Reference Example 5, a concave prism assembly prepared in the same manner as in Reference Example 1 is cut into 5 mm squares in vertical and horizontal external dimensions by a fly-cut method. In this case, instead of cutting the retroreflective element by setting the prism azimuth angle so that the V-shaped groove in the third direction forming the prism intersects at right angles with the lateral side forming the outer shape of the mold unit, this reference is used. After rotating 45 degrees clockwise from the position of Example 5, the prism azimuth angle of the retroreflective element was determined so as to intersect with the horizontal side at an angle of 45 degrees and cut. Hereinafter, in the same manner as in Reference Example 1, the mold structural unit (B₁)created. Table 1 summarizes the factors of the obtained mold constituent units.
[0122]
Reference example 7 (mold structural unit B₂)
Using a brass prism assembly unit prepared in the same manner as in Reference Example 5, a concave prism assembly prepared in the same manner as in Reference Example 1 is cut into 5 mm squares in vertical and horizontal external dimensions by a fly-cut method. In this case, instead of cutting the prism azimuth angle of the retroreflective element so that the X-shaped V-shaped groove forming the prism intersects with the lateral side forming the die structural unit outline at right angles, this reference example The prism was rotated 90 degrees clockwise from the position 5 and the prism azimuth angle of the retroreflective element was determined so as to be parallel to the horizontal side and cut. Hereinafter, in the same manner as in Reference Example 1, the mold structural unit (B₂)created. Table 1 summarizes the factors of the obtained mold constituent units.
[0123]
Reference example 8 (mold structural unit B₃)
Using a brass prism assembly unit prepared in the same manner as in Reference Example 5, a concave prism assembly prepared in the same manner as in Reference Example 1 is cut into 5 mm squares in vertical and horizontal external dimensions by a fly-cut method. In this case, instead of cutting the prism azimuth angle of the retroreflective element so that the X-shaped V-shaped groove forming the prism intersects with the lateral side forming the die structural unit outline at right angles, this reference example The prism azimuth angle of the retroreflective element was determined by cutting 135 degrees clockwise from the position 5 and intersecting the horizontal side at an angle of 45 degrees. Hereinafter, in the same manner as in Reference Example 1, the mold structural unit (B₃)created. Table 1 summarizes the factors of the obtained mold constituent units.
[0124]
Reference example 9 (mold structural unit C₀)
In Reference Example 5, the repetition pitch of the V-shaped grooves in the y-direction and the z-direction is 179.402 μm, the repetition pitch of the V-shaped grooves in the x-direction is 160.732 μm, and the V-shape in the y-direction and the z-direction Brass plate in the same manner as in Reference Example 4 except that the crossing angle of the groove is 67.846 degrees and the crossing angle of the V-shaped groove in the y direction and the x direction is 56.077 degrees. A convex prism assembly unit having a cube-corner retroreflective element group having a reflective element height of 80.000 μm was formed thereon.
[0125]
The optical axis tilt angle of the retroreflective element in the obtained convex prism assembly unit was −7.00 °, and the prism apex angle was 90.000 °.
[0126]
Using the obtained brass prism assembly unit, the mold constituent unit (C₀)created. Table 1 summarizes the factors of the obtained mold constituent units.
[0127]
Reference Example 10 (Mold Component Unit C₁)
When a concave prism assembly produced in the same manner as in Reference Example 9 is cut into 5 mm squares in the vertical and horizontal outer dimensions by fly-cut method, the V-shaped groove in the x direction forming the prism is a mold. Instead of setting and cutting the prism azimuth angle of the retroreflective element so that it intersects at right angles with the horizontal side forming the structural unit outline, the horizontal side is rotated 45 degrees clockwise from the position of this reference example 9 The prism azimuth angle of the retroreflective element was determined so as to intersect at an angle of 45 degrees with the angle and cut. In the same manner as in Reference Example 1, the mold constituent unit (C₁)created. Table 1 summarizes the factors of the obtained mold constituent units.
[0128]
Reference Example 11 (Mold Component Unit C₂)
Using a brass prism assembly unit prepared in the same manner as in Reference Example 9, a concave prism assembly prepared in the same manner as in Reference Example 1 is cut into 5 mm squares in vertical and horizontal external dimensions by fly-cut method. In this case, instead of cutting the prism azimuth angle of the retroreflective element so that the X-shaped V-shaped groove forming the prism intersects with the lateral side forming the die structural unit outline at right angles, this reference example The prism 9 was rotated 90 degrees clockwise from the position 9 and the prism azimuth angle of the retroreflective element was determined so as to be parallel to the horizontal side and cut. In the same manner as in Reference Example 1, the mold constituent unit (C₂)created. Table 1 summarizes the factors of the obtained mold constituent units.
[0129]
Reference Example 12 (Mold Component Unit C₃)
When a concave prism assembly produced in the same manner as in Reference Example 9 is cut into 5 mm squares in the vertical and horizontal outer dimensions by fly-cut method, the V-shaped groove in the x direction forming the prism is a mold. Instead of deciding and cutting the prism azimuth angle of the retroreflective element so as to intersect at right angles with the horizontal side forming the structural unit outline, the horizontal side is rotated 135 degrees clockwise from the position of the reference example 9. The prism azimuth angle of the retroreflective element was determined so as to intersect at an angle of 45 degrees with the angle and cut. In the same manner as in Reference Example 1, the mold constituent unit (C₃)created. Table 1 summarizes the factors of the obtained mold constituent units.
[0130]
Reference Example 13 (Mold Component Unit D₀)
In Reference Example 1, instead of using a diamond bit having a tip angle of 70.529 degrees, the same procedure as in Reference Example 1 was performed except that a V-shaped groove was cut using a diamond bit having a tip angle of 70.599 degrees. A convex prism assembly unit having a cube-corner retroreflective element group having a reflective element height of 79.895 μm was formed on a brass plate.
[0131]
The optical axis tilt angle of the retroreflective element in the obtained convex prism assembly unit is 0 degree, and the prism apex angle has a deviation of 90.000 degrees to +3.00 minutes (+0.0500 degrees), respectively. It was.
[0132]
Using this obtained brass prism assembly unit, the mold constituent unit (D₀)created. Table 1 summarizes the factors of the obtained mold constituent units.
[0133]
Reference example 14 (mold structural unit D₁)
Using a brass prism assembly unit prepared in the same manner as in Reference Example 13, a concave prism assembly prepared in the same manner as in Reference Example 1 is cut into 5 mm squares in vertical and horizontal external dimensions by a fly-cut method. In this case, instead of cutting the prism azimuth angle of the retroreflective element so that the X-shaped V-shaped groove forming the prism intersects with the lateral side forming the die structural unit outline at right angles, this reference example By rotating 45 degrees clockwise from position 13, the prism azimuth angle of the retroreflective element was determined so as to intersect with the horizontal side at an angle of 45 degrees and cut. In the same manner as in Reference Example 1, the mold constituent unit (D₁)created. Table 1 summarizes the factors of the obtained mold constituent units.
[0134]
Reference Example 15 (Mold Component Unit D₂)
Using a brass prism assembly unit prepared in the same manner as in Reference Example 13, a concave prism assembly prepared in the same manner as in Reference Example 1 is cut into 5 mm squares in vertical and horizontal external dimensions by a fly-cut method. In this case, instead of cutting the prism azimuth angle of the retroreflective element so that the X-shaped V-shaped groove forming the prism intersects with the lateral side forming the die structural unit outline at right angles, this reference example The prism was rotated 90 degrees clockwise from position 13 and the prism azimuth angle of the retroreflective element was determined so as to be parallel to the horizontal side and cut. In the same manner as in Reference Example 1, the mold constituent unit (D₂)created. Table 1 summarizes the factors of the obtained mold constituent units.
[0135]
Reference Example 16 (Mold Component Unit D₃)
Using a brass prism assembly unit prepared in the same manner as in Reference Example 13, a concave prism assembly prepared in the same manner as in Reference Example 1 is cut into 5 mm squares in vertical and horizontal external dimensions by a fly-cut method. In this case, instead of cutting the prism azimuth angle of the retroreflective element so that the X-shaped V-shaped groove forming the prism intersects with the lateral side forming the die structural unit outline at right angles, this reference example After rotating 135 degrees clockwise from position 13, the prism azimuth angle of the retroreflective element was determined so as to intersect with the horizontal side at an angle of 45 degrees and cut. In the same manner as in Reference Example 1, the mold constituent unit (D₃)created. Table 1 summarizes the factors of the obtained mold constituent units.
[0136]
Reference Example 17 (Mold Composition Unit E₀)
In Reference Example 5, reflection on a brass plate was performed in the same manner as Reference Example 4 except that cutting was performed using a diamond bit having a tip angle of 77.105 degrees in the y and z directions and 56.600 degrees in the x direction. A convex prism assembly unit having a cube-corner retroreflective element group with an element height of 79.904 μm was formed.
[0137]
The optical axis tilt angle of the retroreflective element in the obtained convex prism assembly unit is +7.00 degrees, and the prism apex angle has a deviation of 90.000 degrees to +3.000 minutes (+0.050 degrees), respectively. Had.
[0138]
Using this brass mother mold, the mold structural unit (E₀)created. Table 1 summarizes the factors of the obtained mold constituent units.
[0139]
Reference Example 18 (Mold Component Unit F₀)
In Reference Example 9, the height of the reflective element is increased on the brass plate in the same manner as in Reference Example 9 except that a diamond tool having a tip angle of 63.188 degrees in the y direction and z direction and 84.599 degrees in the x direction is used. A convex prism assembly unit having a cube-corner retroreflective element group having a length of 79.885 μm was formed.
[0140]
The optical axis inclination angle of the retroreflective element in the obtained convex prism assembly unit is −7.00 degrees, and the prism apex angle is a deviation of 90.000 degrees to +3.000 minutes (+0.050 degrees), respectively. Had.
[0141]
Using this brass mother mold, the mold structural unit (F₀)created. Table 1 summarizes the factors of the obtained mold constituent units.
[0142]
Reference Example 19 (Mold Component Unit G₀)
In Reference Example 5, at a depth of about 40 μm, the repetition pitch of the V-shaped grooves in the y direction and the z direction is 82.091 μm and the repetition pitch of the V-shaped grooves in the x direction is 95.905 μm. A convex prism assembly unit having a cube-corner retroreflective element group with a reflective element height of 40.000 μm was formed on a brass plate in the same manner as in Reference Example 5 except for cutting.
[0143]
Using this brass prism assembly unit, the mold constituent unit (G₀)created. However, when cutting the outer peripheral four sides of a concave prism assembly cut piece made of nickel electroforming by a fly cutting method using a diamond bite, instead of cutting to a depth of 0.1 mm, a depth of 0. It cut so that it might become 060 mm. Table 1 summarizes the factors of the obtained mold constituent units.
[0144]
Reference Example 20 (Mold Component Unit H₀)
In Reference Example 5, at a depth of about 100 μm, the repetition pitch of the V-shaped grooves in the y direction and the z direction is 205.23 μm and the repetition pitch of the V-shaped grooves in the x direction is 239.76 μm. A convex prism assembly unit having a cube-corner retroreflective element group with a reflective element height of 100.000 μm was formed on a brass plate in the same manner as in Reference Example 5 except for cutting.
[0145]
Using this brass prism assembly unit, the mold constituent unit (H₀)created. However, when cutting the outer peripheral four sides of a concave prism assembly cut piece made of nickel electroforming by a fly cutting method using a diamond bite, instead of cutting to a depth of 0.1 mm, a depth of 0. Cutting was performed to 12 mm. Table 1 summarizes the factors of the obtained mold constituent units.
[0146]
Reference Example 21 (Mold Component Unit J₀)
In Reference Example 1, using a diamond bite having a tip angle of 68.529 degrees in the y direction and z direction and 71.519 degrees in the x direction, the repetitive pitch of the V-shaped grooves in the y direction and the z direction is 171 .932 μm, the repetition pitch of the V-shaped groove in the x direction is 168.700 μm, the intersection angle of the V-shaped groove in the y direction and the z direction is 58.760 degrees, and the V shape in the y direction and the x direction A cube-corner retroreflective element group having a reflective element height of 80.000 μm is provided on a brass plate in the same manner as in Reference Example 1, except that the crossing angle of the groove is 60.620 degrees. A convex prism assembly unit was formed.
[0147]
The optical axis tilt angle of the retroreflective element in the obtained convex prism assembly unit was +1.000 degrees, and the prism apex angle was 90.000 degrees.
[0148]
Using the obtained brass prism assembly unit, the mold constituent unit (J₀)created. Table 1 summarizes the factors of the obtained mold constituent units.
[0149]
Reference Example 22 (Mold Component Unit J₁)
Using a brass prism assembly unit prepared in the same manner as in Reference Example 21, a concave prism assembly prepared in the same manner as in Reference Example 1 is cut into 5 mm squares in vertical and horizontal external dimensions by fly-cut method. In this case, instead of cutting the prism azimuth angle of the retroreflective element so that the X-shaped V-shaped groove forming the prism intersects with the lateral side forming the die structural unit outline at right angles, this reference example The prism azimuth angle of the retroreflective element was determined by cutting 45 degrees clockwise from the position 21 and intersecting the horizontal side at an angle of 45 degrees. In the same manner as in Reference Example 1, the mold constituent unit (J₁)created. Table 1 summarizes the factors of the obtained mold constituent units.
[0150]
Reference Example 23 (Mold Component Unit J₂)
Using a brass prism assembly unit prepared in the same manner as in Reference Example 21, a concave prism assembly prepared in the same manner as in Reference Example 1 is cut into 5 mm squares in vertical and horizontal external dimensions by fly-cut method. In this case, instead of cutting the prism azimuth angle of the retroreflective element so that the X-shaped V-shaped groove forming the prism intersects with the lateral side forming the die structural unit outline at right angles, this reference example The prism azimuth angle of the retroreflective element was determined by cutting 90 degrees clockwise from the position 21 and parallel to this lateral side. In the same manner as in Reference Example 1, the mold constituent unit (J₂)created. Table 1 summarizes the factors of the obtained mold constituent units.
[0151]
Reference Example 24 (Mold Component Unit J₃)
Using a brass prism assembly unit prepared in the same manner as in Reference Example 5, a concave prism assembly prepared in the same manner as in Reference Example 1 is cut into 5 mm squares in vertical and horizontal external dimensions by a fly-cut method. In this case, instead of cutting the prism azimuth angle of the retroreflective element so that the X-shaped V-shaped groove forming the prism intersects with the lateral side forming the die structural unit outline at right angles, this reference example The prism azimuth angle of the retroreflective element was determined by cutting 135 degrees clockwise from the position 21 and intersecting the horizontal side at an angle of 45 degrees. In the same manner as in Reference Example 1, the mold constituent unit (J₃)created. Table 1 summarizes the factors of the obtained mold constituent units.
[0152]
[Table 1]

[0153]
Reference Example 25 (Mold M for Unit Retroreflectance Coefficient R Measurement₁And retroreflective sheet S₁)
A 100 mm square combination body was created using a total of 100 10 mm * 10 mm prism assembly units A0, 10 by 10 mm, prepared by the method of Reference Example 1, and the electroforming method was repeated twice using this as a matrix. Unit retroreflectance coefficient R measurement cube corner mold M₁It was created.
[0154]
Next, this mold M₁300 μm-thick polycarbonate resin sheet [trade name “Iupilon E3000”; manufactured by Mitsubishi Engineering Plastics Co., Ltd.] at a molding temperature of 200 ° C. and a molding pressure of 50 kg / cm²Polycarbonate resin that was compression molded under the conditions of the following, then cooled to 30 ° C. under pressure, then taken out of the resin sheet, and cube corner retroreflective elements with a cube corner prism layer thickness of 200 μm arranged on the surface Cube Corner Retroreflective Sheet S for Unit Retroreflective Coefficient R Measurement₁It was created. The obtained retroreflective sheet S₁The angle formed by the x direction of the prism (the direction of the groove defined by the base shared by the pair of elements) and the vertical direction of the measuring device (prism azimuth angle ω) Measure the retroreflectance coefficient at 0 degree, 45 degree, 90 degree and 135 degree to determine the mold unit A₀The unit retroreflectance coefficient R at each prism azimuth angle of the sealed enclosure unit based on The obtained unit retroreflectance coefficient R is shown in Table 2.
[0155]
Reference Example 26 (Mold M for Unit Retroreflectance Coefficient R Measurement₂And retroreflective sheet S₂)
In Reference Example 25, the prism assembly unit A created by the method of Reference Example 1₀The prism assembly unit B created by the method of Reference Example 5 instead of using₀A mold M for measuring unit retroreflectance coefficient R in the same manner as in Reference Example 25 except that₂And retroreflective sheet S₂And retroreflective sheet S in the same manner as in Reference Example 25.₂The retroreflective coefficient at the prism azimuth angles of 0 °, 45 °, 90 ° and 135 ° of₀The unit retroreflectance coefficient R at each prism azimuth angle of the sealed enclosure unit based on The obtained unit retroreflectance coefficient R is shown in Table 2.
[0156]
Reference Example 27 (Mold M for Unit Retroreflectance Coefficient R Measurement₃And retroreflective sheet S₃)
In Reference Example 25, instead of using the prism assembly unit A0 created by the method of Reference Example 1, instead of using the prism assembly unit C0 created by the method of Reference Example 9, the unit retroreflectance coefficient is similar to that of Reference Example 25. Mold M for R measurement₃And retroreflective sheet S₃And retroreflective sheet S in the same manner as in Reference Example 25.₃The retroreflectance coefficient at the prism azimuth angles of 0 °, 45 °, 90 °, and 135 ° was measured, and the mold unit C₀The unit retroreflectance coefficient R at each prism azimuth angle of the sealed enclosure unit based on The obtained unit retroreflectance coefficient R is shown in Table 2.
[0157]
Reference Example 28 (Mold M for Unit Retroreflectance Coefficient R Measurement₄And retroreflective sheet S₄)
In Reference Example 25, instead of using the prism assembly unit A0 created by the method of Reference Example 1, instead of using the prism assembly unit D0 created by the method of Reference Example 13, the unit retroreflectance coefficient is the same as Reference Example 25. Mold M for R measurement₄And retroreflective sheet S₄And retroreflective sheet S in the same manner as in Reference Example 25.₄The retroreflectance coefficient at the prism azimuth angles of 0 °, 45 °, 90 ° and 135 ° of₀The unit retroreflectance coefficient R at each prism azimuth angle of the sealed enclosure unit based on The obtained unit retroreflectance coefficient R is shown in Table 2.
[0158]
Reference Example 29 (Mold M for Unit Retroreflectance Coefficient R Measurement₅And retroreflective sheet S₅)
In Reference Example 25, instead of using the prism assembly unit A0 created by the method of Reference Example 1, the unit retroreflectance coefficient is the same as that of Reference Example 25 except that the prism assembly unit E0 created by the method of Reference Example 17 is used. Mold M for R measurement₅And retroreflective sheet S₅And retroreflective sheet S in the same manner as in Reference Example 25.₅The retroreflectance coefficient at the prism azimuth angle of 0 degrees was measured and the mold constituent unit E₀The unit retroreflectance coefficient R of the sealed enclosure unit based on The obtained unit retroreflectance coefficient R is shown in Table 2.
[0159]
Reference Example 30 (Mold M for Unit Retroreflectance Coefficient R Measurement₆And retroreflective sheet S₆)
In Reference Example 25, instead of using the prism assembly unit A0 created by the method of Reference Example 1, the unit retroreflectance coefficient is similar to that of Reference Example 25 except that the prism assembly unit F0 created by the method of Reference Example 18 is used. Mold M for R measurement₆And retroreflective sheet S₆And retroreflective sheet S in the same manner as in Reference Example 25.₆The retroreflectance coefficient at a prism azimuth angle of 0 degrees was measured and the mold unit F₀The unit retroreflectance coefficient R of the sealed enclosure unit based on The obtained unit retroreflectance coefficient R is shown in Table 2.
[0160]
Reference Example 31 (Mold M for Unit Retroreflectance Coefficient R Measurement₇And retroreflective sheet S₇)
In Reference Example 25, instead of using the prism assembly unit A0 created by the method of Reference Example 1, the unit retroreflectance coefficient is similar to that of Reference Example 25 except that the prism assembly unit G0 created by the method of Reference Example 19 is used. Mold M for R measurement₇And retroreflective sheet S₇And retroreflective sheet S in the same manner as in Reference Example 25.₇The retroreflectance coefficient at the prism azimuth angle of 0 degrees was measured and the mold unit G₀The unit retroreflectance coefficient R of the sealed enclosure unit based on The obtained unit retroreflectance coefficient R is shown in Table 2.
[0161]
Reference Example 32 (Unit M for retroreflectance coefficient R measurement₈And retroreflective sheet S₈)
In Reference Example 25, instead of using the prism assembly unit A0 created by the method of Reference Example 1, the unit retroreflectance coefficient is similar to that of Reference Example 25 except that the prism assembly unit H0 created by the method of Reference Example 20 is used. Mold M for R measurement₈And retroreflective sheet S₈And retroreflective sheet S in the same manner as in Reference Example 25.₈The retroreflectance coefficient at a prism azimuth angle of 0 ° was measured and the mold unit H₀The unit retroreflectance coefficient R of the sealed enclosure unit based on The obtained unit retroreflectance coefficient R is shown in Table 2.
[0162]
Reference Example 33 (Mold M for Unit Retroreflectance Coefficient R Measurement₉And retroreflective sheet S₉)
In Reference Example 25, instead of using the prism assembly unit A0 created by the method of Reference Example 1, the unit retroreflectance coefficient is similar to that of Reference Example 25 except that the prism assembly unit J0 created by the method of Reference Example 21 is used. Mold M for R measurement₉And retroreflective sheet S₉And retroreflective sheet S in the same manner as in Reference Example 25.₉The retroreflectance coefficient at the prism azimuth angle of 0 degrees was measured and the mold constituent unit J₀The unit retroreflectance coefficient R of the sealed enclosure unit based on The obtained unit retroreflectance coefficient R is shown in Table 2.
[0163]
[Table 2]

[0164]
[Example 1]
In Reference Example 21, instead of creating a 100 mm square combination by using a total of 100 10 mm * 10 mm prism assembly prism assembly units of 10 mm * 10 mm created by the method of Reference Example 1, the above Reference Example 1 and Mold unit A of 5 mm * 5 mm created in Reference Example 13₀And D₀Are combined two by two to form a minimum repeating unit having an outer shape of 10 mm square as shown in FIG. 13 consisting of 4 mold constituent units, and this minimum repeating unit is further added to the vertical and horizontal units of 10 units for a total of 100 units. A cube corner mold was formed in the same manner as in Reference Example 21 except that a combination body having an outer shape of 100 mm square was prepared by combining.
Using this mold, a cube-corner retroreflective sheet made of polycarbonate resin in which cube-corner retroreflective elements having a cube-corner prism layer thickness of 200 μm are arranged on the surface in the same manner as in Reference Example 21 is used. Created. Measurement of the aggregate retroreflectance coefficient of the obtained retroreflective sheet and evaluation of the appearance were performed according to the method described later. Table 3 shows the measurement results.
[0165]
[Example 2]
Mold unit B created in Reference Example 5 and Reference Example 9₀And C₀A cube corner mold was formed in the same manner as in Example 1 except that a minimum repeating unit having an outer shape of 10 mm square as shown in FIG.
[0166]
Thereafter, in the same manner as in Reference Example 21, a cube corner retroreflective sheet made of polycarbonate resin in which cube corner retroreflective elements having a cube corner prism layer thickness of 200 μm were arranged in a close-packed manner on the surface was prepared. Measurement of the aggregate retroreflectance coefficient of the obtained retroreflective sheet and evaluation of the appearance were performed according to the method described later.
Table 3 shows the measurement results.
[0167]
[Example 3]
Mold unit A created in Reference Example 1, Reference Example 5 and Reference Example 9₀, B₀And C₀Are combined to form a minimum repeating unit with an outer shape of 15 mm square as shown in FIG. 15 consisting of 9 mold constituent units, and this minimum repeating unit is further combined with a total of 64 units of 8 units vertically and horizontally for a total of 120 units. A cube corner mold was formed in the same manner as in Example 1 except that a combination was prepared.
[0168]
Thereafter, in the same manner as in Reference Example 21, a cube corner retroreflective sheet made of polycarbonate resin in which cube corner retroreflective elements having a cube corner prism layer thickness of 200 μm were arranged in a close-packed manner on the surface was prepared. Measurement of the aggregate retroreflectance coefficient of the obtained retroreflective sheet and evaluation of the appearance were performed according to the method described later.
Table 3 shows the measurement results.
[0169]
[Example 4]
Mold unit A created in Reference Examples 1 to 4 and Reference Examples 13 to 16₀, A₁, A₂, A₃, D₀, D₁, D₂And D₃Are combined to form a minimum repeating unit having an outer shape of 40 mm square as shown in FIG. 16 and comprising 64 mold constituent units, and this minimum repeating unit is further combined in a total of 25 units of 3 units in the vertical and horizontal directions, and a total of 25 units is combined. A cube corner mold was formed in the same manner as in Example 1 except that a combination was prepared.
[0170]
Thereafter, in the same manner as in Reference Example 21, a cube corner retroreflective sheet made of polycarbonate resin in which cube corner retroreflective elements having a cube corner prism layer thickness of 200 μm were arranged in a close-packed manner on the surface was prepared. Measurement of the aggregate retroreflectance coefficient of the obtained retroreflective sheet and evaluation of the appearance were performed according to the method described later.
Table 3 shows the measurement results.
[0171]
[Example 5]
Mold unit B created in Reference Examples 5-12₀, B₁, B₂, B₃, C₀, C₁, C₂And C₃17 to form a minimum repeat unit with an outer shape of 40 mm square as shown in FIG. 17 composed of 64 mold constituent units, and this minimum repeat unit is further combined with a total of 25 units of 3 units in the vertical and horizontal directions for a total of 120 mm square. A cube corner mold was formed in the same manner as in Example 1 except that a combination was prepared.
[0172]
Thereafter, in the same manner as in Reference Example 21, a cube corner retroreflective sheet made of polycarbonate resin in which cube corner retroreflective elements having a cube corner prism layer thickness of 200 μm were arranged in a close-packed manner on the surface was prepared. Measurement of the aggregate retroreflectance coefficient of the obtained retroreflective sheet and evaluation of the appearance were performed according to the method described later.
Table 3 shows the measurement results.
[0173]
[Example 6]
Mold unit G created in Reference Example 19 and Reference Example 20₀And H₀A cube corner mold was formed in the same manner as in Example 1 except that a minimum repeating unit having an outer shape of 10 mm square as shown in FIG.
[0174]
Thereafter, in the same manner as in Reference Example 21, a cube corner retroreflective sheet made of polycarbonate resin in which cube corner retroreflective elements having a cube corner prism layer thickness of 200 μm were arranged in a close-packed manner on the surface was prepared. Measurement of the aggregate retroreflectance coefficient of the obtained retroreflective sheet and evaluation of the appearance were performed according to the method described later.
Table 3 shows the measurement results.
[0175]
[Example 7]
Mold structural unit B created in Reference Example 5, Reference Example 9, Reference Example 17 and Reference Example 18₀, C₀, E₀And F₀To form a 20 mm square minimum repeating unit consisting of 16 mold constituent units as shown in FIG. A cube corner mold was formed in the same manner as in Example 1 except that a combination was prepared.
[0176]
Thereafter, in the same manner as in Reference Example 21, a cube corner retroreflective sheet made of polycarbonate resin in which cube corner retroreflective elements having a cube corner prism layer thickness of 200 μm were arranged in a close-packed manner on the surface was prepared. Measurement of the aggregate retroreflectance coefficient of the obtained retroreflective sheet and evaluation of the appearance were performed according to the method described later.
Table 3 shows the measurement results.
[0177]
[Example 8]
Mold unit A created in Reference Example 1 and Reference Example 21₀And J₀A cube corner mold was formed in the same manner as in Example 1 except that a minimum repeating unit having an outer shape of 10 mm square as shown in FIG.
[0178]
Thereafter, in the same manner as in Reference Example 21, a cube corner retroreflective sheet made of polycarbonate resin in which cube corner retroreflective elements having a cube corner prism layer thickness of 200 μm were arranged in a close-packed manner on the surface was prepared. Measurement of the aggregate retroreflectance coefficient of the obtained retroreflective sheet and evaluation of the appearance were performed according to the method described later.
Table 3 shows the measurement results.
[0179]
[Comparative Example 1]
Mold unit A created in Reference Example 1 and Reference Example 3₀And A₂A cube corner mold was formed in the same manner as in Example 1 except that a minimum repeating unit having an outer shape of 10 mm square as shown in FIG.
[0180]
Thereafter, in the same manner as in Reference Example 21, a cube corner retroreflective sheet made of polycarbonate resin in which cube corner retroreflective elements having a cube corner prism layer thickness of 200 μm were arranged in a close-packed manner on the surface was prepared. Measurement of the aggregate retroreflectance coefficient of the obtained retroreflective sheet and evaluation of the appearance were performed according to the method described later.
Table 3 shows the measurement results.
[0181]
[Table 3]

[0182]
The unit retroreflectance coefficient R and the aggregate retroreflectance coefficient were measured and the appearance was evaluated by the following method.
[0183]
Unit retroreflectance coefficient R
Advanced Retro Technology as a retroreflective performance measuring instrument
(Advanced Retro Technology, Inc.) "Model (MODEL) 920" manufactured according to JIS z-9117 and made by the method of Reference Examples 21 to 28, each retroreflective sheet consisting of the same sealed enclosure units S₁~ S₈The amount of retroreflected light (cd / Lx · cm at an incident angle of 5 degrees and an observation angle of 0.20 degrees described in each of these reference examples)²) And the unit retroreflectance coefficient R at each prism azimuth angle of each sealed enclosure unit.
[0184]
Next, in each of Examples 1 to 8 and Comparative Example 1, the maximum value among the unit retroreflective coefficients R of the sealed enclosure units based on the combined mold constituent units is R._maxAnd the smallest value is R_minAs R_min/ R_maxAnd the ratio R of the unit retroreflective coefficient R of the blocks of adjacent sealed units or blocks of the sealed units._L/ R_H(However, R_L≦ R_H) To find the minimum value.
[0185]
Aggregate retroreflectance coefficient
Using the same retroreflective performance measuring instrument used for the measurement of the unit retroreflectance coefficient R, the amount of retroreflective light of the 100 mm * 100 mm retroreflective sheet obtained in Examples 1 to 8 and Comparative Example 1 was measured according to JIS. According to Z-9117, the amount of retroreflected light (cd / L x · cm at an incident angle of 5 and 30 degrees and an observation angle of 0.20 and 1.0 degrees at prism azimuth angles of 0 and 45 degrees, respectively)²) To obtain the aggregate retroreflectance coefficient of these examples or comparative examples.
[0186]
Appearance evaluation
The 100 mm * 100 mm retroreflective sheets obtained in Examples 1 to 8 and Comparative Example 1 were visually observed for appearance and evaluated according to the following criteria.
◎ …… Difference in brightness between mold units is not noticeable.
○ …… The difference in brightness between the mold components is hardly noticeable.
Δ: Slight difference in brightness between mold components.
× …… The difference in brightness between the mold components is clearly visible.
[0187]
【The invention's effect】
The present invention is a mold constituent unit having a prism assembly unit comprising a prism assembly surface in which cube-corner retroreflective elements are arranged in a close-packed manner on a substrate and a peripheral wall surrounding the prism assembly surface. The mold structural unit includes a retroreflective element in which the optical axis of the cube-corner retroreflective element is inclined, and at least one prism apex angle of the retroreflective element has a slight deviation from 90 degrees. A cube corner mold in which at least two types of different mold constituent units including a mold constituent unit having a prism assembly unit selected from the elements are combined, and molding using this mold The cube-corner-type retroreflective sheet can satisfy the three wide-angle characteristics, that is, the incident angle characteristic, the observation angle characteristic, and the rotation angle characteristic. A problem with the design of the sheet appearance, which is one of the important commercial values of the projection sheet, that is, the section of the prism assembly surface can be seen quite clearly from the surface of the retroreflective sheet even when the sheet is viewed from close. It was possible to improve the problems.
[0188]
[Brief description of the drawings]
FIG. 1 is an enlarged perspective view schematically showing a triangular pyramid prism assembly unit, which is a typical embodiment of a prism assembly unit used for creating a cube corner mold of the present invention.
FIG. 2 is a cross-sectional view of a hermetically sealed unit having a triangular pyramid prism assembly surface, which is a typical embodiment of the hermetically sealed unit constituting the cube-corner retroreflective sheet of the present invention.
FIG. 3 is a schematic view showing a shape of a top portion of a peripheral wall in a prism assembly unit of a cube corner mold or a sealed enclosure unit of a cube corner type retroreflective sheet according to the present invention.
FIG. 4 is an enlarged view of a prism assembly surface within a prism assembly unit or a triangular pyramid cube corner retroreflective sheet sealing enclosure unit for forming a triangular pyramid cube corner mold, which is a typical embodiment of the present invention. It is a top view.
5 is a further enlarged plan view of a pair of triangular pyramidal cube corner retroreflective element pairs in FIG. 4. FIG.
6 is a cross-sectional view of a pair of triangular pyramidal cube corner retroreflective elements cut along the line AA in FIG. 5;
FIG. 7 is an enlarged view of a prism assembly surface in a prism assembly unit for constituting a triangular pyramid cube corner mold or a sealed enclosure unit of a triangular pyramid cube corner retroreflective sheet according to another embodiment of the present invention. It is a top view.
8 is a further enlarged plan view of a pair of triangular pyramidal cube corner retroreflective element pairs in FIG. 7. FIG.
9 is a cross-sectional view of a triangular pyramid cube corner retroreflective element pair obtained by cutting the retroreflective element pair in FIG. 8 along a cutting line BB.
FIG. 10 is a cross-sectional view (a) and an enlarged plan view (b) for schematically explaining the center line of the V-shaped groove bottom.
FIG. 11 is a conceptual diagram showing the arrangement of hermetically sealed units or mold constituent units in the minimum repeating unit of the cube corner retroreflective sheet or cube corner mold of the present invention.
FIG. 12 shows a sealed enclosing unit in a case where a block of a sealed enclosing unit or a block of 4 mold constituent units is formed in the minimum repeating unit of the cube corner retroreflective sheet or cube corner mold of the present invention; It is a conceptual diagram which shows the arrangement | sequence of a mold structural unit.
FIG. 13 is a conceptual diagram showing a minimum repeating unit composed of four mold constituent units in Example 1, which is an embodiment of the present invention.
14 is a conceptual diagram showing a minimum repeating unit composed of four mold constituent units in Example 2, which is another embodiment of the present invention. FIG.
FIG. 15 is a conceptual diagram showing a minimum repeating unit composed of nine mold constituent units in Example 3, which is another embodiment of the present invention.
FIG. 16 is a conceptual diagram showing a minimum repeating unit composed of 64 mold constituent units in Example 4, which is another embodiment of the present invention.
FIG. 17 is a conceptual diagram showing the minimum repeating unit composed of 64 mold constituent units in Example 5, which is another embodiment of the present invention.
FIG. 18 is a conceptual diagram showing a minimum repeating unit composed of four mold constituent units in Example 6, which is another embodiment of the present invention.
FIG. 19 is a conceptual diagram showing a minimum repeating unit composed of 16 mold constituent units in Example 7, which is another embodiment of the present invention.
20 is a conceptual diagram showing a minimum repeating unit composed of four mold constituent units in Example 8, which is another embodiment of the present invention. FIG.
FIG. 21 is a conceptual diagram showing a minimum repeating unit composed of four mold constituent units in Comparative Example 1, which is an embodiment of the prior art.
[0189]
[Explanation of symbols]
1 ... Cube corner type retroreflective element
2 …… Prism assembly surface
3 ... Surrounding wall
4 ... Prism layer
5 ... Retainer layer
6 ... Binder layer
7 …… Air layer
8 …… Surface layer
9 …… Support layer
10 …… Adhesive layer
11 …… Peeling material layer
12 ... V-shaped groove
13. A straight line formed by intersecting the plane or curved surface of the bottom (12) of the V-shaped groove with the plane that bisects the V-shaped groove angle.
14 ... Bottom of V-shaped groove (12)
c₁, C₂... Side-facing sides of two retroreflective elements facing each other with a common base
a₁, A₂, B₁, B₂... of retroreflective element (c₁, C₂Aspects other than
H: Top of retroreflective element
P: Intersection of the perpendicular line drawn from the top to the bottom of the retroreflective element and the bottom
Q: Intersection of the optical axis of the retroreflective element and the bottom surface
p: Distance from intersection (P) to base shared by retroreflective element pair
q: Distance from the intersection (Q) to the base shared by the retroreflective element pair
L, M, N,... Each represents a mold constituent unit based on a sealed enclosure unit composed of different cube-corner retroreflective elements or a prism assembly unit.

Claims (13)

A light-transmitting prism layer is a prism in which a light incident side surface is substantially smooth and a light-transmitting holding layer, and cube-corner retroreflective elements are arranged in a close-packed manner on the back surface of the holding layer A binder comprising an aggregate surface and a peripheral wall formed together with the retroreflective element that protrudes beyond the top of the retroreflective element and surrounds the prism aggregate surface, and is disposed with an air layer separated from the prism layer A cube comprising an assembly of hermetically sealed units comprising an air layer surrounded by a peripheral wall, a prism assembly surface, and an air layer surrounded by the binder layer, wherein the top of the peripheral wall of the prism layer is connected to the binder layer. A corner-type retroreflective sheet, which is a sealed enclosing unit having a prism assembly surface in which one type of retroreflective elements is arranged in a close-packed manner in a sealing structure surrounded by a peripheral wall, Small In the cube-corner retroreflective sheet in which at least two types are combined, the cube-corner retroreflective sheet has a retroreflective structure in which the optical axis of the reflective element is inclined with respect to the normal of the surface on the light incident side. A prism layer composed of elements and / or a retroreflective element in which at least one of the crossing angles (prism apex angles) formed by two of the three surfaces constituting the retroreflective element has a slight deviation from 90 degrees. A cube-corner retroreflective sheet comprising a prism layer made of The cube-corner retroreflective sheet according to claim 1, wherein the cube-corner retroreflective element is a triangular pyramid cube-corner retroreflective element. The cube-corner retroreflective sheet according to claim 1 or 2, wherein a deviation of a prism apex angle of the cube-corner retroreflective element is in a range of ± 0.001 degrees to ± 0.2 degrees. The triangular pyramidal cube corner retroreflective element is a retroreflective element pair sharing one base, and a common base shared by the element pair is determined from an intersection (Q) between the optical axis of the retroreflective element and the bottom surface. In addition, the distance from the top surface (H) to the bottom surface of the retroreflective element and the intersection (P) between the bottom surface and the bottom surface of the retroreflective element is a common base shared by the element pair. In addition, when the distance to the plane perpendicular to the bottom surface is p, the optical axis of the retroreflective element is in the direction in which the difference (qp) between these distances is plus or minus with respect to the perpendicular The cube-corner retroreflective sheet according to claim 2 or 3, which is inclined within a range of 0.5 degrees to 12 degrees. Of the three-direction V-shaped grooves forming the triangular pyramid-shaped cube corner retroreflective element, at least one direction of the V-shaped groove is formed at a different depth from the other directions of the V-shaped grooves. The cube-corner retroreflective sheet according to any one of claims 2 to 4, further comprising a hermetically sealed unit that includes the element to be enclosed. The cube corner according to any one of claims 1 to 5, wherein the cube-corner retroreflective sheet includes a combination of at least two kinds of hermetically sealed units having prism assembly surfaces having different prism azimuth angles of the cube-corner retroreflective element. Type retroreflective sheet. The ratio R _min / R _max between the maximum value R _max and the minimum value R _min of the unit retroreflectance coefficient R of each prism assembly surface in a plurality of types of sealed enclosure units constituting the cube corner type retroreflective sheet is 0.5 or more. The cube-corner retroreflective sheet according to any one of claims 1 to 6. A prism assembly surface in which cube-corner retroreflective elements projecting on one side of one substrate are arranged in a close-packed manner, and projecting beyond the top of the retroreflective device from the substrate to surround the prism assembly surface A cube corner mold formed by combining a large number of mold constituent units each including a surrounding wall, and has a prism assembly surface in which one kind of retroreflective elements are arranged in a close-packed manner in the peripheral wall. In the cube corner mold in which at least two types of mold structural units are combined, the cube corner mold has an optical axis of the cube corner type retroreflective element of the retroreflective element. A mold constituent unit having a retroreflective element inclined with respect to a normal to the substrate and / or each of two pre-forms formed by two of the three surfaces constituting the retroreflective element At least one beam apex angle is cube-corner mold, characterized in that it comprises a mold structure unit having a prism set unit consisting of retroreflective elements having a slight deviation from 90 degrees. The cube corner mold according to claim 8, wherein the cube corner retroreflective element is a triangular pyramid cube corner retroreflective element. The cube corner mold according to claim 8 or 9, wherein a deviation of a prism apex angle of the cube corner retroreflective element is in a range of ± 0.001 degrees to ± 0.2 degrees. The triangular pyramidal cube corner retroreflective element is a retroreflective element pair sharing one base, and the element pair includes a common base from the intersection (Q) of the optical axis of the retroreflective element and the bottom surface, The distance from the top surface (H) of the retroreflective element to the bottom surface is defined as q, and the distance from the top surface (H) of the retroreflective element to the bottom surface and the bottom surface shared by the element pair from the intersection (P) of the bottom surface When the distance to the vertical plane is p, the optical axis of the retroreflective element is 0.5 degrees with respect to the perpendicular in the direction in which the difference (qp) between these distances is positive or negative. The cube corner mold according to claim 9 or 10, which is inclined in a range of -12 degrees. Of the three-direction V-shaped grooves forming the triangular pyramid-shaped cube corner retroreflective element, at least one direction of the V-shaped groove is formed at a different depth from the other directions of the V-shaped grooves. The cube corner metal mold according to any one of claims 9 to 11, further comprising a metal mold constituent unit including the element. The cube corner mold according to any one of claims 8 to 12, wherein the cube corner mold includes a combination of at least two mold constituent units having prism assembly surfaces having different prism azimuth angles of the cube corner retroreflective element. Type.

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