JP4289569B2

JP4289569B2 - Sheet for molding and molding method using the same

Info

Publication number: JP4289569B2
Application number: JP19546498A
Authority: JP
Inventors: 浩之阿竹
Original assignee: Dai Nippon Printing Co Ltd
Current assignee: Dai Nippon Printing Co Ltd
Priority date: 1998-07-10
Filing date: 1998-07-10
Publication date: 2009-07-01
Anticipated expiration: 2018-07-10
Also published as: JP2000025103A

Description

【０００１】
【発明の属する技術分野】
本発明は、真空成形によって成形されるシートと、それを用いた成形方法に関する。特に、基材シートに積層された樹脂層に、成形時の伸びでクラック（亀裂）が発生しない技術に関する。
【０００２】
【従来の技術】
従来から、樹脂基材からなるシートを真空成形して成形品としたり、或いは更にシートの真空成形（以下、真空圧空成形も包含する）を利用して、立体形状の被着体にシートを積層して成形品とする事も行われている（例えば、真空成形積層法、射出成形同時絵付け法）。これらの場合、真空成形するシートとして、樹脂製の基材シートに絵柄等を印刷形成して絵柄を有する樹脂層を積層した成形用シートを用いれば、成形品は模様や文字等で絵付された物とできる。また、被着体に成形用シートを適用する場合、成形用シートを積層したままとすれば成形用シートのラミネート加工であり、成形用シートを積層後に、基材シートのみを剥離除去して樹脂層のみを積層すれば、成形用シートによる転写加工となる。
【０００３】
例えば、基材シート上に塗装膜等の樹脂層が積層された構成の成形用シートを化粧シートとして用いて、真空成形を利用して立体形状の被着体を化粧する技術として、所謂真空成形積層法が、▲１▼特開平３−３２８９９号公報、▲２▼特公平６−６９７５９号公報、▲３▼特開平６−９２０８８号公報、▲４▼特開昭５８−２２２８７５号公報等に開示されている。
そして、この様な真空成形用途に使用される成形用シートは、図１に例示する如く、樹脂からなる基材シートＢ上に、樹脂層Ｒとして、絵柄層１や接着剤層２等が用途に応じて積層された構成のものである。そして、前記▲１▼〜▲３▼の従来技術の成形用シートでは、基材シートとしては可塑剤部数８ｐｈｒ程度の塩化ビニル樹脂を、また絵柄層等の樹脂層には、ニトロセルロースが用いられており、また、▲４▼の成形用シートでは、基材シートに塩化ビニル樹脂、樹脂層にはアクリル樹脂が用いられている。
【０００４】
【発明が解決しようとする課題】
ところで、成形用シートを真空成形によって被着体にラミネ−ト法又は転写法で適用して成形品とするにせよ、或いは、成形用シート単独の真空成形品とするにせよ、成形用シートを加熱軟化させて真空成形する時は、該シートは十分に伸びる必要がある。この為、真空成形は、基材シートＢの軟化温度ｔｓｂ付近のシート加熱温度で行うのが普通である。しかし、前記の成形用シートは基材シートに積層されている樹脂層の伸びがその温度では伸びずに微細なクラックが樹脂層に発生する事がある。クラックは、得られる成形品の外観を損ない、意匠的な欠点にもなる。また、クラックが発生した樹脂層が基材シート或いは被着体との接着に寄与する接着剤層であると、接着剤層に微小なクラックが入っている状態となるので、密着不良を起こす。しかも、透明な接着剤層であると、見た目ではクラックが分かりにくく、密着性が安定した生産が不可能であった。
そこで、シート加熱温度をより高い温度として、基材シートに積層されている樹脂層の樹脂が十分に軟化される温度まで成形用シートを加熱してから、真空引きをして真空成形すると、今度は、昇温時間が延びて生産性が低下したり、成形用シートが加熱され過ぎて、シートが極度に伸びやすくなり、皺が発生したりした。
【０００５】
そこで、本発明の課題は、真空成形用の成形用シートにて、基材シート上の樹脂層のクラック発生を防ぎ、且つシートに皺を発生させない様にする事である。また、この様な成形用シートを用いる成形方法を提供する事である。
【０００６】
【課題を解決するための手段】
そこで上記課題を解決すべく、本発明の成形用シートでは、
基材シートと、該基材シートに積層され且つ該基材シートよりも薄い、少なくとも１層の樹脂層とからなる、成形用シートにおいて、
前記基材シートがアクリル樹脂からなり、
前記樹脂層が、塩素化ポリオレフィン、アクリル樹脂、ポリ塩化ビニル、ポリ酢酸ビニル、塩化ビニル−酢酸ビニル共重合体、ブチラール樹脂、熱可塑性ポリエステル樹脂、熱可塑性ウレタン樹脂、ポリアミド樹脂、或いは、ゴム系樹脂の熱可塑性樹脂を用いた接着剤層を含むものであって、
前記基材シートの軟化温度Ｔｓｂに対して、該接着剤層を含む前記全ての樹脂層の軟化温度Ｔｓｒが、Ｔｓｒ≦Ｔｓｂである、
構成とした。この結果、樹脂層を基材シート以上に伸び易く出来る為、成形用シートが真空成形される時に、樹脂層にクラックが発生しない。従って、クラック発生による外観不良や樹脂層を接着剤層とした時の被着体との密着不良を防げる。
【０００７】
また、本発明の成形方法の第１の形態は、真空成形積層法で上記成形用シートを真空成形して被着体に適用する成形方法である。すなわち、本発明の成形用シートを、立体形状の被着体の表面に対して、前記接着剤層を介して対向又は載置し、成形用シートの表裏両側の気圧差を少なくとも被着体側からの真空吸引によって発生させ、少なくとも該気圧差によって成形用シートを真空成形して被着体に押圧して密着、積層し、ラミネ−トの場合は、そのまま成形用シート全層が被着体に積層した成形品とし、転写の場合は、次いで基材シートを剥離して樹脂層のみが被着体に積層した成形品とする、真空成形積層法による成形方法とする。この結果、既に形の有る被着体に対して成形用シートを適用する場合に、その樹脂層のクラック発生による外観不良や、樹脂層を接着剤層とした時の被着体との密着不良を防げる。
【０００８】
また、本発明の成形方法の第２の形態は、射出成形同時絵付け法で前記成形用シートを真空成形して被着体に適用する成形方法である。すなわち、本発明の成形用シートを、一対の型の間に挿入して該型を真空成形型として真空成形した後、両型を型締めし、両型で形成されるキャビティ内に流動状態の樹脂を充填して、成形と同時に樹脂成形物表面に成形用シートを密着、積層させた後、両型を型開きし、ラミネ−トの場合は、そのまま成形用シート全層が樹脂成形物からなる被着体に積層した成形品とし、転写の場合は、更に基材シートを剥離して樹脂層のみが樹脂成形物からなる被着体に積層した成形品とする、射出成形同時絵付け法による成形方法とする。
この結果、樹脂成形物からなる被着体の成形と同時に成形用シートを適用する場合に、その樹脂層のクラック発生による外観不良や、樹脂層を接着剤層とした時の被着体との密着不良を防げる。
【０００９】
【発明の実施の形態】
以下、図面を参照しながら本発明の成形用シート及びそれを用いた成形方法について、実施の形態を説明する。
【００１０】
〔概要〕
図１は、本発明の成形用シートの一形態を例示する断面図である。本発明の成形用シートＳは、基材シートＢと、基材シートに積層される少なくとも１層からなる基材シートよりも薄い樹脂層Ｒとからなり、基材シートＢと樹脂層Ｒの各々の軟化温度を特定の関係としたシートである。図１に例示の形態の成形用シートは、樹脂層Ｒが装飾層１と接着剤層２との２層かなる構成の場合である。
すなわち、樹脂層Ｒの厚さＤｒは、基材シートＢの厚さＤｂよりも小さく、Ｄｒ＜Ｄｂの関係が成立し、樹脂層Ｒを構成する樹脂の軟化温度ＴｓであるＴｓｒは、基材シートＢの軟化温度ＴｓであるＴｓｂ以下で、Ｔｓｒ≦Ｔｓｂの関係が成立する様にしたシートである。なお、樹脂層Ｒの厚さＤｒが、基材シートＢの厚さＤｂよりも大きく、Ｄｒ＞Ｄｂならば、樹脂層４が成形用シートの全厚の主体を占める事になり、樹脂層４が「基材」シートと言うべき事になってしまう。従って、樹脂層が「基材」では無い条件がＤｒ＜Ｄｂである。すなわち、本発明では、樹脂積層体からなる成形用シートの構成層のうち、厚みが過半数を占める方の層が成形用シート全体の成形性の大半を決定することになる。そこで、成形用シートの厚みの大半を占める層を「基材シート」と呼び、先ず、この層の熱機械的挙動を適切なものに選定し、次いで成形用シートの厚みの半分未満を占める方の層、すなわち「樹脂層」の熱機械的挙動をそれに追従させることにする。
この結果、樹脂層の軟化温度Ｔｓｒは、基材シートの軟化温度Ｔｓｂ以下、或いはせいぜい等しいので、樹脂層を基材シート以上に伸びやすい状態で、真空成形できるので、基材シートの熱成形の変移（歪み）に十分追従し、樹脂層のクラック発生を防げる。
【００１１】
なお、図１は概念図で有る為に、樹脂層Ｒの軟化温度Ｔｓｒは単純化して説明したが、図１に例示の如く、樹脂層Ｒが装飾層１と接着剤層２との２層からなる等と、複層からなる場合は、樹脂層Ｒを構成する各層について各々の軟化温度Ｔｓが基材シートの軟化温度Ｔｓｂ以下とする。すなわち、図１の場合で言えば、装飾層１の軟化温度Ｔｓｒ１は、Ｔｓｒ１≦Ｔｓｂとして、接着剤層２の軟化温度Ｔｓｒ２は、Ｔｓｒ２≦Ｔｓｂとする。
なお、本発明に於ける軟化温度Ｔｓは、定荷重乃至は応力を加えて加熱したときに、十分な変形を生じる温度を客観的に評価した温度であれば、特に測定法は問わない。その理由は、本発明では軟化温度は、一つの材料の固有の特性を評価する為に用いるのではなく、あくまでも基材シートと樹脂層との同温度に於ける変形の程度の差を比較する為に用いるからである。軟化温度としては、Ｖｉｃａｔ軟化温度（ＪＩＳＫ７２０６規定）が通常良く用いられるが、その他、クラッシュバーガー歪軟温度（ＪＩＳＫ６７４５規定）、荷重撓み温度（ＪＩＳ７２０７規定）等でも良い。
【００１２】
なお、本発明の成形用シートは、該成形用シート自体のみで成形品とする場合もあるが、被着体に適用する場合には、ラミネートタイプのシートの他に、転写タイプのシートでも良い。これらのうち転写タイプでは、被着体に成形用シートを積層後、基材シートは剥離し、樹脂層のみが被着体に積層した成形品とする。
【００１３】
樹脂層と基材シートの軟化温度を前記の様な関係に設定する為には、例えば、基材シートを構成する樹脂系と、樹脂層を構成する樹脂系とが、同一の場合では、樹脂層側の樹脂について、その重合度Ｐ（分子量でも良い）を基材シートよりも小さくして軟化温度Ｔｓｒを下げたり、或いは、異種の単量体を共重合させたり、可塑剤を樹脂系に添加したり、より軟化温度の低い樹脂を混合したりして、樹脂層の軟化温度Ｔｓｒを下げれば良い。
【００１４】
また例えば、基材シートの厚さが１２５μｍで、樹脂層の厚さが５μｍの場合を一例とすれば、▲１▼重合度の場合では、基材シートにはポリメチルメタクリレートの平均重合度１３００の樹脂を使用し、樹脂層にはポリメチルメタクリレートの平均重合度８００の樹脂を使用する。
▲２▼また、共重合の場合では、基材シートにはポリメチルメタクリレートの単独重合体の平均重合度１１００の樹脂を使用し、樹脂層にはメチルメタクリレートとブチルメタクリレートの共重合体の重合度１１００の樹脂を使用する。
▲３▼また、共重合の場合の別の例としては、基材シートには、塩化ビニル単独重合体を使用し、樹脂層には、塩化ビニル−酢酸ビニル共重合体（９０対１０重量比の共重合体）を用い、平均重合度はともに８６０、可塑剤ＤＯＰ（ジオクチルフタレート）含有量はともに１０ｐｈｒとする。
▲４▼また、可塑剤の場合では、基材シートには、可塑剤ＤＯＰ（ジオクチルフタレート）を１０ｐｈｒ含有の平均重合度２０００の塩化ビニル樹脂を使用し、樹脂層には可塑剤ＤＯＰを２０ｐｈｒ含有の平均重合度２０００の塩化ビニル樹脂を使用する。
▲５▼或いは、基材シートにはポリメチルメタクリレートの単独重合体の平均重合度１１００の樹脂のみを使用し、樹脂層にはポリメチルメタクリレートの単独重合体の平均重合度１１００の樹脂１００重量部と、塩化ビニル−酢酸ビニル共重合体（９０対１０重量比の平均重合度７００の共重合体）１００重量部との混合樹脂を使用する。
▲６▼或いはまた、基材シートには、アイソタクチックポリプロピレン９０重量部とアタクチックポリプロピレン１０重量部とからなる樹脂を使用し、樹脂層にはアイソタクチックポリプロピレン７５重量部とアタクチックポリプロピレン２５重量部からなる樹脂を使用する。
【００１５】
以下、更に本発明を詳述する。
【００１６】
〔成形用シート：基材シート〕
基材シートとしては、熱成形性の有る樹脂シートを用いる。該樹脂シートとしては、例えば、ポリプロピレン、ポリエチレン、ポリブテン、ポリメチルペンテン、エチレン−プロピレン共重合体、エチレン−プロピレン−ブテン共重合体、オレフィン系熱可塑性エラストマー等のポリオレフィン系樹脂、エチレン−イソフタレート−テレフタレート共重合体、ポリブチレンテレフタレート等のポリエステル樹脂、ナイロン等のポリアミド樹脂、塩化ビニル樹脂、アクリル樹脂、ＡＢＳ樹脂（アクリロニトリル−ブタジエン−スチレン共重合体）、ウレタン系等のその他の熱可塑性エラストマー、等の熱可塑性樹脂のシートを用いる。基材シートの厚みは、特に限定されないが、一般的には３０〜５００μｍ程度であり、転写タイプでは２０〜２００μｍ程度である。
なお、転写タイプでは、基材シートには樹脂層との離型性の有るシートを使用する。この為に必要に応じて、基材シートの樹脂層側には、樹脂層との剥離性を向上させる為、公知の離型層を設けた構成の基材シートとする。離型層は基材シートの剥離時に基材シートと一体となって転写層上から除去されるものである。離型層には、例えば、シリコーン樹脂、ワックス等が用いられる。なお、離型層は０．１〜４μｍ程度であり基材シート全体の軟化温度への影響は微小である。また、ラミネートタイプでは、基材シート樹脂中に染料、顔料等の着色剤を練り込んで、基材シートを着色透明又は着色不透明、或いは無色不透明等とする装飾処理を施す事もある。
【００１７】
〔成形用シート：樹脂層〕
樹脂層を、基材シート上に積層するには、フィルム状のものを貼り合わせても良いし、印刷法や塗工法で積層しても良い。樹脂層の厚さは、基材シートよりも薄くするが、通常１〜１００μｍ程度である。
樹脂層は、通常、顔料や染料等の着色剤を添加し、全面又は部分的に、塗工、印刷、樹脂フィルムの接着等の方法によって積層する。成形用シートを被着体にラミネ−トする為に使用する場合、樹脂層は成形用シートが被着体に接する側に積層しても良いが、その反対側に積層しても良い。後者の場合、成形用シートが被着体に積層された後は、樹脂層は表面保護層等として用いる事ができる。
【００１８】
樹脂層の樹脂としては、熱成形性の有る樹脂を用いる。該樹脂としては、例えば、印刷や塗工で形成する場合には、塩素化ポリエチレン、塩素化ポリプロピレン等の塩素化ポリオレフィン、ポリ（メタ）アクリル酸メチル、ポリ（メタ）アクリル酸エチル、ポリ（メタ）アクリル酸ブチル、（メタ）アクリル酸メチル−（メタ）アクリル酸ブチル共重合体、（メタ）アクリル酸メチル−スチレン共重合体等のアクリル樹脂、熱可塑性ポリエステル樹脂、熱可塑性ウレタン樹脂、酢酸ビニル樹脂、塩化ビニル−酢酸ビニル共重合体、可塑化セルロース系樹脂等の熱可塑性樹脂を単体で或いは２種以上混合して用いる。更に、樹脂層を樹脂フィルムの接着で積層する場合には、ポリプロピレン、ポリエチレン、エチレン−プロピレン共重合体、オレフィン系熱可塑性エラストマー等のポリオレフィン系樹脂、エチレン−イソフタレート−テレフタレート共重合体、ポリブチレンテレフタレート等のポリエステル樹脂等の前記基材シートとして列記した樹脂等も前記の如く軟化温度と厚みの関係さえ満たせば使用できる。また樹脂フィルム中に顔料等の着色剤を練り込んで、樹脂フィルムを着色透明又は着色不透明等とする事もある。
【００１９】
樹脂層は、基材シートの全面にわたって形成されていても良いし、部分的に模様状に形成されていても良い。また層構成としては、単層の場合も有るが、印刷や塗工等で部分又は全面に２層以上積層した装飾層や、接着剤層等の場合もある（図１参照）。これらは、公知の方法で積層すれば良い。装飾層の場合には、例えば、上記樹脂等をバインダーの樹脂とするビヒクルに、必要に応じ更に着色剤、体質顔料等の各種添加剤を添加したインキ（又は塗液）の印刷（又は塗工）で積層すれば良い。印刷は、グラビア印刷、オフセット印刷、シルクスクリーン印刷、転写シートからの転写印刷等の公知の印刷法で良い。塗工は、ロールコート、グラビアコート等の公知の塗工法で良い。なお、着色剤としては、例えば、チタン白、亜鉛華、弁柄、朱、群青、コバルトブルー、チタン黄、黄鉛、カーボンブラック等の無機顔料、イソインドリノン、ハンザイエローＡ、キナクリドン、パーマネントレッド４Ｒ、フタロシアニンブルー、インダスレンブルーＲＳ、アニリンブラック等の有機顔料（或いは染料も含む）、アルミニウム、真鍮等の箔粉からなる金属顔料、二酸化チタン被覆雲母、塩基性炭酸鉛等の箔粉からなる真珠光沢（パール）顔料等を用いる。
装飾層の模様は任意だが、例えば、木目模様、石目模様、布目模様、皮絞模様、幾何学図形、文字、記号、或いは全面ベタ等がある。
【００２０】
また、接着剤層は、樹脂層と被着体との接着性を向上させる為に、必要に応じて設ける。接着剤層に用いる樹脂としては、例えば、塩素化ポリエチレン、塩素化ポリプロピレン等の塩素化ポリオレフィン、前記の如きアクリル樹脂、ポリ塩化ビニル、ポリ酢酸ビニル、塩化ビニル−酢酸ビニル共重合体、ブチラール樹脂、熱可塑性ポリエステル樹脂、熱可塑性ウレタン樹脂、ポリアミド樹脂、或いは、ポリイソプレンゴム、ポリイソブチルゴム、スチレンブタジエンゴム、ブタジエンアクリロニトリルゴム等のゴム系樹脂の熱可塑性樹脂を用いる。
【００２１】
〔成形方法〕
本発明の成形用シートを用いた真空成形方法（含む真空圧空成形）としては、先ず、成形用シートの真空成形で得られた成形物を、最終的な成形品とする所謂真空成形法がある。この他、成形用シートを被着体に真空成形を利用して積層し、ラミネ−トタイプの成形用シートの場合は、そのまま成形用シート全層が被着体に積層した成形品とし、転写タイプの成形用シートの場合は、次いで基材シートを剥離して樹脂層のみが被着体に積層した成形品とする方法がある。
【００２２】
（真空成形積層法）
本発明の成形方法の第１の方法は、特公昭５６−４５７６８号公報（オーバーレイ法）、特公昭６０−５８０１４号公報（真空プレス法）、特開平４−３６８８３７号公報（オーバーレイ法及び真空プレス法）等に記載されるように、立体形状の被着体の表面に成形用シートを、間に必要に応じ適宜接着剤を介して対向又は載置し、被着体側からの真空吸引による圧力差により成形用シートを被着体に積層し、転写の場合はその後、基材シートを剥離して樹脂層のみを積層する、所謂真空成形積層法に、上述した特定の成形用シートを使用する方法である。なお、転写の場合は、もちろん成形用シートはその樹脂層側を被着体側に向けて対向又は載置する。
【００２３】
図２は、この真空成形積層法の中でも、真空プレス法の説明図である。真空プレス法は、オーバーレイ法（真空ラミネート法）と似ているが、成形用シートの被着体への押圧に空気の圧力差以外に、弾性体膜としてゴム状弾性膜の収縮力（収縮圧）も利用する点、成形用シートの加熱をヒータにより加熱されたゴム状弾性膜を通して行う点等が若干異なり、成形用シートの均一加熱とより強い押圧力等に特徴がある。
【００２４】
同図の概略構成図に示す真空プレス装置３０は、上方には流体圧シリンダー等の上下動作機構１３により上下に移動可能な上室１１があり、上室１１に対面して下方に下室２１がある。上室１１の内部には赤外線輻射型のヒータ１２が配置されている。また上室１１の下部開口面はゴム状弾性膜１５にて全面が覆われている。ゴム状弾性膜１５には通常シリコーンゴム等が用いられる。下室２１はその上面が複数の排気孔２３を有する置台２２となっている。上室１１及び下室２１には、それぞれ給排気ポート１４、２４があり、それぞれの内部圧を独立に調整できる。
真空プレス法では、先ず、上室１１が上方に移動して下室２１と分離した状態で、被着体Ｗを置台２２に配置し、さらに成形用シートＳを被着体Ｗの上から配置する。その際、転写タイプの成形用シートＳの場合は転写層となる樹脂層側が被着体Ｗと向き合う様にする。接着剤を成形用シートや被転写体の外表面に施しておく場合には、この段階で塗布などしておく。また接着剤が溶剤を含む場合は、この段階で乾燥させておく。
次いで、上室１１を下方に移動し下室２１に圧接し、上室１１及び下室２１を密閉する。図２はこの状態を示している。次に、下室２１内を減圧し、上室１１内を加圧する。さらに、ヒータ１２を用いてゴム状弾性膜１５を通して成形用シートＳを加熱軟化させ成形可能状態とする。この結果、成形用シートＳは上室１１と下室２１との空気の圧力差及びゴム状弾性膜１５の収縮圧により押圧されて、被着体Ｗの外表面に沿って変形圧接され、成形用シートＳが被着体Ｗへ密着し、積層していく。
最後に、下室２１の減圧を解除するとともに上室１１の加圧を解除して両室を大気圧にし、上室１１を上方に移動し上室１１及び下室２１を分離し、成形用シートＳが積層した被着体Ｗを取り出す。ラミネ−トタイプの成形用シートの場合は、成形用シートＳが積層した被着体Ｗがそのまま成形品となる。また、転写タイプの成形用シートの場合は、更にこの後、成形用シートの基材シートを剥離し樹脂層のみを転写層として残し、樹脂層が被着体に積層された成形品を得る。
【００２５】
なお、被着体側に接着剤を施す場合の該接着剤としては、成形用シートの樹脂層の接着剤層で列記した樹脂等からなる接着剤を使用すれば良い。接着剤はスプレーコート等の公知の塗工法で被着体に施す。
【００２６】
なお、被着体Ｗとしては、立体形状であれば特に限定はなく、例えばその材質は、木質系、プラスチック系、無機系、金属系等を使用できる。具体的には、杉、檜、ラワン等の各種樹木からなる木材単板や木材合板、パーティクルボード、集成材、木質中密度繊維板（ＭＤＦ）等の木質材料、ポリプロピレン、ＡＢＳ樹脂、フェノール樹脂等のプラスチック材料、ケイ酸カルシウム、ＡＬＣ（軽量気泡コンクリート）、ＧＲＣ（硝子繊維強化コンクリート）、パルプセメント等の非陶磁器窯業系材料、陶器、磁器、硝子、琺瑯等のセラミックス等の無機質材料等の無機系材料、或いは、鉄、アルミニウム、銅等の金属材料等である。
【００２７】
（射出成形同時絵付け法）
また、本発明の成形方法の第２の方法は、特開平６−３１５９５０号公報、特公平２−４２０８０号公報等に記載されるように、転写タイプの成形用シートを射出成形の雌雄両型間に配置した後、流動状態の樹脂を型内に射出充填し、樹脂成型品の成形と同時にその表面に成形用シートから転写層として樹脂層を転写させる、転写タイプに適用する所謂射出成形同時絵付け転写法、或いは、特公昭５０−１９１３２号公報、特公昭４３−２７４８８号公報等に記載されるように、ラミネ−トタイプの成形用シートを射出成形の雌雄両型間に配置した後、流動状態の樹脂を型内に射出充填し、樹脂成型品の成形と同時にその表面に成形用シートを積層させる、ラミネ−トタイプに適用する所謂射出成形同時絵付けラミネ−ト法等の、所謂射出成形同時絵付け法に上述した特定の成形用シートを使用する方法である。なお、転写の場合は、もちろん成形用シートはその樹脂層側を成形樹脂側に向けて配置する。また、成形用シートは、型間に配置する前に、外部で真空成形しておくこともできるが皺等が出来やすい為、好ましくは、成形用シートを型間に配置した後、射出成形型を真空成形型として真空成形してから、樹脂を射出する。
【００２８】
図３は、射出成形同時絵付け法のうちの射出成形同時絵付けラミネ−ト法を説明する概念図である。本発明では、成形用シートは、型締めする前に成形用シートを型間で加熱し軟化させて射出成形型を真空成形型として用いて真空成形により予備成形した後に、型締めして樹脂を射出する。
【００２９】
先ず、図３（Ａ）の如く、射出成形型としては、射出ノズルと連通する湯道（ランナー）及び湯口（ゲート）を有する型Ｍａと、型面に吸引孔４１を有しシートの予備成形型を兼用する型Ｍｂの一対の成形型を用いる。型は鉄等の金属、又はセラミックスを用いる。型開き状態に於いて型Ｍｂに成形用シートＳを枠状のクランプ（不図示）で押圧する等して固定する。次いで、図３（Ｂ）の如く、ヒータ４２で成形用シートを加熱軟化させる（ここでは非接触の輻射加熱の例だが接触加熱でも良い）。そして、図３（Ｃ）の如く吸引孔から吸引して真空成形して、成形用シートを型Ｍｂのキャビティ面に沿わせ予備成形する。なお、真空成形は圧空も併用する真空圧空成形でも良い。次いで、図３（Ｄ）の如く両型を型締めし、図３（Ｅ）の如く両型で形成さるキャビティに加熱熔融状態等の流動状態の樹脂を充填する。そして、樹脂が冷却等で固化後、型開きして成形物を取り出し、成形用シートの不要部分があれば適宜トリミングすれば、図３（Ｆ）の如く、樹脂成形物からなる被着体Ｗに成形用シートＳがラミネートされた形態の成形品Ｐが得られる。
【００３０】
射出成形する成形樹脂は、従来公知の射出成形同時絵付け方法に於ける公知のもの等が使用でき特に制限されるものではない。例えば、熱可塑性樹脂であれば、ポリエチレン、ポリプロピレン等のポリオレフィン系樹脂、塩化ビニル樹脂、アクリル樹脂、ＡＢＳ（アクリロニトリル−ブタジエン−スチレン共重合体）樹脂、スチレン樹脂、ＡＳ（アクリロニトリル−スチレン共重合体）樹脂、ポリカーボネート樹脂等があり、硬化性樹脂であれば、不飽和ポリエステル樹脂、硬化性アクリル樹脂、２液硬化型ウレタン樹脂、エポキシ樹脂等がある。
熱可塑性樹脂は加熱熔融により流動状態として射出してキャビティ内で冷却固化させ、熱硬化性樹脂はその未硬化物を適宜加熱して流動状態で射出して反応硬化で固化させる。
【００３１】
〔成形品の用途〕
本発明で得られる成形品の用途は、特に限定されず各種用途に用いられ得る。例えば、壁面、天井、床等の建築物の内装建材用途、サイディング等の外壁、塀、屋根、門扉、破風板等の外装材用途、窓枠、扉、手摺、敷居、鴨居等の建具類の表面化粧材用途、箪笥等の家具やテレビ受像機等の弱電・ＯＡ機器のキャビネットの表面化粧材用途、自動車、電車等の車両、航空機、船舶等の各種乗物の内装材用途、或いは、瓶、化粧品容器、小物入れ等の各種包装容器及び材料、景品や小物等の雑貨等のその他各種用途に用いられ得る。
【００３２】
【実施例】
以下、実施例及び比較例により本発明を更に詳述する。
【００３３】
〔参考例１〕
基材シートとして、厚み１２５μｍのアクリル樹脂シートを用意した。該アクリル樹脂は、メチルメタクリレート−ブチルメタクリレート共重合体と、アクリルゴムとの混合物からなる樹脂である。また、このアクリル樹脂シートの軟化温度Ｔｓｂは９０℃であった。そして、この基材シートの片面に、樹脂層として絵柄を有する総厚５μｍの装飾層を、バインダーの樹脂にアクリル樹脂と塩化ビニル−酢酸ビニル共重合体との１対１重量比の混合樹脂（Ｖｉｃａｔ軟化温度Ｔｓｒは６５℃）を用いたビヒクルに、弁柄とカーボンブラックを主体とする着色顔料を添加してなる着色インキをグラビア印刷して積層して、成形用シートを得た。
【００３４】
上記成形用シートを、３００℃に加熱したセラミックヒータから３０ｍｍ遠ざけた位置で５秒間加熱した後、真空成形して、縦３００ｍｍ、横２００ｍｍで深さ方向３０ｍｍ、角部の曲率半径４ｍｍの箱型形状の成形品を得た。その際、成形用シートの温度は９０℃であった。樹脂層には伸びされた部分でもクラックは発生しなかった。
【００３５】
〔比較例１〕
参考例１において、樹脂層に用いた樹脂（バインダーの樹脂）を、メチルメタクリレートを主体とする樹脂（Ｖｉｃａｔ軟化温度Ｔｓｒは１００℃）に代えた他は、参考例１と同様にして成形用シートを作製し、参考例１同様に真空成形した。その結果、成形用シートが伸びていない部分の樹脂層にはクラック発生は無かったが、シートが約６０％伸ばされている部分では、樹脂層に微細なクラックが発生している箇所があり、意匠的に劣っていた。
【００３６】
〔参照例１〕
参考例１の成形用シートの樹脂層の装飾層の上に、更に厚さ２μｍの接着剤層を、アクリル樹脂と塩化ビニル−酢酸ビニル共重合体との１対１重量比の混合樹脂（Ｖｉｃａｔ軟化温度Ｔｓは６５℃）からなるインキをグラビア印刷して積層し、装飾層及び接着剤層からなる樹脂層とした成形用シートを用意した。この成形用シートを、適用面が平面状の樹脂成形物（被着体）を成形する射出成形金型内に固定した後、型締めし、溶融したアクリル樹脂（２５０℃）を金型温度７０℃の条件で射出成形した。その結果、成形用シートが被着体に密着良く積層された成形品が得られた。もちろん、成形用シートは伸ばされていないので、樹脂層にクラック発生は無かった。
【００３７】
〔参照例２〕
参照例１に於いて、接着剤層の樹脂をポリメチルメタクリレートを主体とするアクリル樹脂（Ｖｉｃａｔ軟化温度Ｔｓは１００℃）に代えた他は、参照例１と同様にして、成形用シートが積層された成形品を得た。その結果、成形用シートが被着体に密着良く積層された成形品が得られた。もちろん、成形用シートは伸ばされていないので、樹脂層にクラック発生は無かった。
【００３８】
〔実施例１〕
参照例１で用いた成形用シートを用いて、今度は、射出成形金型として樹脂成形物（被着体）の形状が縦３００ｍｍ、横２００ｍｍで深さ方向３０ｍｍ、角部の曲率半径４ｍｍの箱型の金型を用いて射出成形同時絵付けを行った。成形用シートを金型に固定した後、ヒータで該シートを９０℃に加熱した後、金型内から真空引きして真空成形して雌型のキャビティ面に沿わせた。次いで、型締めし、溶融したアクリル樹脂（２５０℃）を金型温度７０℃の条件で射出成形した。その結果、成形用シートが樹脂成形物の被着体に密着良く積層された成形品が得られた。また、コーナ部分で成形用シートが伸ばされ場所でも、樹脂層にクラック発生は無かった。また、成形品上の成形用シートに、樹脂成形物まで達する縦・横各々１ｍｍ間隔の碁盤目状の切り込みを入れ、その表面にセロハン粘着テープ（ニチバン株式会社製、「セロテープ」（登録商標）２４ｍｍ幅、産業用）を２５℃に於いて貼着した後、勢い良く剥がす、碁盤目試験を行ったところ、成形用シートが剥がれは無かった。
【００３９】
〔比較例２〕
参照例２で用いた成形用シートを用いて、参考例１と同様にして成形品を得た。その結果、コーナ部分で成形用シートが伸ばされ場所での密着が悪く、成形品上の成形用シートに、樹脂成形物まで達する縦・横各々１ｍｍ間隔の碁盤目状の切り込みを入れ、その表面にセロハン粘着テープ（ニチバン株式会社製、「セロテープ」（登録商標）２４ｍｍ幅、産業用）を２５℃に於いて貼着した後、勢い良く剥がす、碁盤目試験を行ったところ、成形用シートが剥がれてしまった。
【００４０】
【発明の効果】
▲１▼本発明の成形用シートによれば、その基材シートと樹脂層との間の厚み及び軟化温度を特定関係としてあるので、成形用シートが真空成形される時に、樹脂層のクラックが発生しない。従って、クラック発生による外観不良や樹脂層を接着剤層とした時の被着体との密着不良が起きない。
▲２▼また、本発明の成形方法によれば、上記の成形用シートを用いる事によって、その樹脂層のクラック発生による外観不良や、樹脂層を接着剤層とした時の被着体との密着不良が起きない。真空成形積層法では既に形の有る被着体に対して成形用シートを適用でき、射出成形同時絵付け法では、被着体の成形と同時に成形用シートを適用できる。
【図面の簡単な説明】
【図１】本発明の成形用シートの一形態を例示する断面図。
【図２】本発明の成形方法の一形態として、真空プレスによる真空成形積層法の説明図。
【図３】本発明の成形方法の一形態として、ラミネ−ト形式の射出成形同時絵付け法の説明図。
【符号の説明】
１装飾層
２接着剤層
１１上室
１２ヒータ
１３上下動作機構
１４、２４吸排気ポート
１５ゴム状弾性膜
２１下室
２２置き台
２３排気孔
３０真空プレス装置
４１吸引孔
４２ヒータ
Ｂ基材シート
Ｄｂ基材シートの厚さ
Ｄｒ樹脂層の厚さ
Ｍａ射出成形型（雄型）
Ｍｂ射出成形型（雌型）
Ｐ成形品
Ｒ樹脂層
Ｓ成形用シート
Ｔｓｂ基材シートの軟化温度
Ｔｓｒ樹脂層の軟化温度
Ｗ被着体[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a sheet formed by vacuum forming and a forming method using the sheet. In particular, the present invention relates to a technique in which a crack (crack) does not occur due to elongation during molding in a resin layer laminated on a base sheet.
[0002]
[Prior art]
Conventionally, a sheet made of a resin base material is vacuum-molded into a molded product, or further, the sheet is laminated on a three-dimensional adherend by using vacuum forming of the sheet (hereinafter also including vacuum / pressure forming). It is also made into a molded product (for example, vacuum forming lamination method, injection molding simultaneous painting method). In these cases, if a molding sheet in which a pattern or the like is printed on a resin base material sheet and a resin layer having a pattern is laminated is used as a vacuum forming sheet, the molded product is painted with a pattern or letters. You can do it. Also, when a molding sheet is applied to an adherend, if the molding sheet is left laminated, the molding sheet is laminated. After the molding sheet is laminated, only the base sheet is peeled and removed. If only the layers are laminated, transfer processing by a molding sheet is performed.
[0003]
For example, so-called vacuum forming is a technique for making a three-dimensional adherend using vacuum forming by using a forming sheet having a structure in which a resin layer such as a coating film is laminated on a base sheet as a decorative sheet. Lamination methods are described in (1) JP-A-3-32899, (2) JP-B-6-69759, (3) JP-A-6-92088, (4) JP-A-58-222875, etc. It is disclosed.
And the sheet | seat for shaping | molding used for such a vacuum forming use uses the pattern layer 1, the adhesive bond layer 2, etc. as the resin layer R on the base material sheet | seat B which consists of resin, as illustrated in FIG. It is the thing of the structure laminated | stacked according to. In the prior art molding sheets (1) to (3), a vinyl chloride resin having a plasticizer part number of about 8 phr is used as a base sheet, and nitrocellulose is used as a resin layer such as a pattern layer. In the molding sheet (4), a vinyl chloride resin is used for the base sheet and an acrylic resin is used for the resin layer.
[0004]
[Problems to be solved by the invention]
By the way, whether the molding sheet is applied to the adherend by vacuum lamination by the laminating method or the transfer method to form a molded product, or whether the molding sheet is a single vacuum molded product, the molding sheet is When vacuum forming by heat softening, the sheet needs to stretch sufficiently. For this reason, vacuum forming is usually performed at a sheet heating temperature near the softening temperature tsb of the base sheet B. However, in the above-described molding sheet, the elongation of the resin layer laminated on the base sheet does not extend at that temperature, and fine cracks may occur in the resin layer. A crack impairs the external appearance of the obtained molded product, and also becomes a design defect. In addition, if the resin layer in which the crack is generated is an adhesive layer that contributes to adhesion to the base sheet or the adherend, the adhesive layer is in a state of minute cracks, which causes poor adhesion. In addition, when the adhesive layer is transparent, cracks are difficult to see and it is impossible to produce with stable adhesion.
Therefore, when the sheet heating temperature is set to a higher temperature and the molding sheet is heated to a temperature at which the resin of the resin layer laminated on the base sheet is sufficiently softened, vacuuming is performed and vacuum molding is performed. The temperature rise time was prolonged and the productivity was lowered, or the sheet for molding was heated too much, the sheet became extremely easy to stretch and wrinkles were generated.
[0005]
Accordingly, an object of the present invention is to prevent cracking of the resin layer on the base material sheet and prevent wrinkling of the sheet in the forming sheet for vacuum forming. Moreover, it is providing the shaping | molding method using such a sheet | seat for shaping | molding.
[0006]
[Means for Solving the Problems]
  Therefore, in order to solve the above problems, in the molding sheet of the present invention,
  In a molding sheet comprising a base sheet and at least one resin layer laminated on the base sheet and thinner than the base sheet,
The base sheet is made of acrylic resin,
The resin layer is chlorinated polyolefin, acrylic resin, polyvinyl chloride, polyvinyl acetate, vinyl chloride-vinyl acetate copolymer, butyral resin, thermoplastic polyester resin, thermoplastic urethane resin, polyamide resin, or rubber resin. Including an adhesive layer using a thermoplastic resin of
For the softening temperature Tsb of the base sheet,Including the adhesive layerSaidAll ofThe softening temperature Tsr of the resin layer is Tsr ≦ Tsb.
The configuration. As a result, since the resin layer can be easily stretched beyond the base sheet, no cracks are generated in the resin layer when the molding sheet is vacuum-formed. Accordingly, it is possible to prevent poor appearance due to cracks and poor adhesion with the adherend when the resin layer is used as an adhesive layer.
[0007]
Moreover, the 1st form of the shaping | molding method of this invention is a shaping | molding method which vacuum-forms the said sheet | seat for shaping | molding with a vacuum forming lamination method, and applies it to a to-be-adhered body. That is, the molding sheet of the present invention, with respect to the surface of the three-dimensional adherend,The adhesive layerThe pressure difference between the front and back sides of the molding sheet is generated by vacuum suction from at least the adherend side, and the molding sheet is vacuum-formed by at least the pressure difference and pressed against the adherend. In the case of lamination, in the case of lamination, it is a molded product in which all layers of the molding sheet are laminated on the adherend, and in the case of transfer, the substrate sheet is then peeled off and only the resin layer is attached. It is set as the shaping | molding method by the vacuum forming lamination method which is set as the molded article laminated | stacked on. As a result, when a molding sheet is applied to an adherend that already has a shape, poor appearance due to the occurrence of cracks in the resin layer and poor adhesion to the adherend when the resin layer is used as an adhesive layer Can be prevented.
[0008]
A second embodiment of the molding method of the present invention is a molding method in which the molding sheet is vacuum-formed by an injection molding simultaneous painting method and applied to an adherend. That is, after the molding sheet of the present invention is inserted between a pair of molds and the mold is vacuum-molded as a vacuum-molding mold, both molds are clamped and fluidized in a cavity formed by both molds. After the resin is filled and the molding sheet is adhered and laminated to the surface of the molded product at the same time as molding, both molds are opened, and in the case of lamination, the entire molding sheet layer is taken directly from the resin molding. Injection molding simultaneous painting method, in which in the case of transfer, the base sheet is further peeled off and the resin layer is laminated on the adherend consisting of a resin molded product. The molding method is as follows.
As a result, when a molding sheet is applied simultaneously with the molding of an adherend made of a resin molded product, the appearance defect due to the occurrence of cracks in the resin layer, and the adherend when the resin layer is used as an adhesive layer Prevents poor adhesion.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the molding sheet and the molding method using the same according to the present invention will be described with reference to the drawings.
[0010]
〔Overview〕
FIG. 1 is a cross-sectional view illustrating one embodiment of the molding sheet of the present invention. The molding sheet S of the present invention comprises a base sheet B and a resin layer R that is thinner than the base sheet composed of at least one layer laminated on the base sheet, and each of the base sheet B and the resin layer R. Is a sheet having a specific relationship with the softening temperature. The molding sheet illustrated in FIG. 1 has a configuration in which the resin layer R is composed of two layers of a decorative layer 1 and an adhesive layer 2.
That is, the thickness Dr of the resin layer R is smaller than the thickness Db of the base sheet B, the relationship of Dr <Db is established, and Tsr which is the softening temperature Ts of the resin constituting the resin layer R is It is a sheet in which the relationship of Tsr ≦ Tsb is established below Tsb which is the softening temperature Ts of the sheet B. If the thickness Dr of the resin layer R is larger than the thickness Db of the base sheet B and Dr> Db, the resin layer 4 will occupy the entire thickness of the molding sheet. Becomes the “base material” sheet. Therefore, the condition that the resin layer is not the “base material” is Dr <Db. That is, in the present invention, of the constituent layers of the molding sheet made of the resin laminate, the layer having the majority of the thickness determines most of the moldability of the entire molding sheet. Therefore, the layer that occupies most of the thickness of the molding sheet is called a “base sheet”. First, select the appropriate thermomechanical behavior of this layer, and then occupy less than half the thickness of the molding sheet. The thermomechanical behavior of this layer, that is, the “resin layer” is made to follow it.
As a result, since the softening temperature Tsr of the resin layer is equal to or lower than the softening temperature Tsb of the base sheet, at most, the resin layer can be vacuum-formed in a state where it can be easily stretched beyond the base sheet. Sufficiently follow the displacement (strain) and prevent cracks in the resin layer.
[0011]
Since FIG. 1 is a conceptual diagram, the softening temperature Tsr of the resin layer R has been described in a simplified manner. However, as illustrated in FIG. 1, the resin layer R is composed of two layers, a decorative layer 1 and an adhesive layer 2. When it consists of multiple layers, the softening temperature Ts of each layer constituting the resin layer R is set to be equal to or lower than the softening temperature Tsb of the base sheet. That is, in the case of FIG. 1, the softening temperature Tsr1 of the decoration layer 1 is Tsr1 ≦ Tsb, and the softening temperature Tsr2 of the adhesive layer 2 is Tsr2 ≦ Tsb.
The softening temperature Ts in the present invention is not particularly limited as long as it is an objective evaluation of the temperature at which sufficient deformation occurs when heated by applying a constant load or stress. The reason is that in the present invention, the softening temperature is not used for evaluating the inherent characteristics of one material, but only the difference in the degree of deformation at the same temperature of the base sheet and the resin layer is compared. This is because it is used for this purpose. As the softening temperature, the Vicat softening temperature (JIS K 7206 standard) is usually used, but in addition, a crash burger strain softening temperature (JIS K 6745 standard), a load deflection temperature (JIS 7207 standard), or the like may be used.
[0012]
In addition, the molding sheet of the present invention may be a molded product only by the molding sheet itself, but when applied to an adherend, a transfer type sheet may be used in addition to the laminate type sheet. . Among these, in the transfer type, after the molding sheet is laminated on the adherend, the base sheet is peeled off and only the resin layer is laminated on the adherend.
[0013]
In order to set the softening temperature of the resin layer and the base sheet to the above relationship, for example, in the case where the resin system constituting the base sheet and the resin system constituting the resin layer are the same, the resin For the resin on the layer side, the degree of polymerization P (which may be molecular weight) is made smaller than that of the base sheet to lower the softening temperature Tsr, or a different kind of monomer is copolymerized, or the plasticizer is made into a resin system. The softening temperature Tsr of the resin layer may be lowered by adding or mixing a resin having a lower softening temperature.
[0014]
Further, for example, when the thickness of the base sheet is 125 μm and the thickness of the resin layer is 5 μm, for example, (1) In the case of the polymerization degree, the average polymerization degree of polymethyl methacrylate is 1300 in the base sheet. A resin having an average polymerization degree of polymethyl methacrylate of 800 is used for the resin layer.
(2) In the case of copolymerization, a resin having an average polymerization degree of 1100 of a polymethyl methacrylate homopolymer is used for the base sheet, and the polymerization degree of the copolymer of methyl methacrylate and butyl methacrylate is used for the resin layer. 1100 resin is used.
(3) As another example of copolymerization, a vinyl chloride homopolymer is used for the base sheet, and a vinyl chloride-vinyl acetate copolymer (90 to 10 weight ratio) is used for the resin layer. The average degree of polymerization is 860, and the plasticizer DOP (dioctyl phthalate) content is 10 phr.
(4) In the case of a plasticizer, a vinyl chloride resin having an average polymerization degree of 2000 containing 10 phr of a plasticizer DOP (dioctyl phthalate) is used for the base sheet, and 20 phr of the plasticizer DOP is contained in the resin layer. A vinyl chloride resin having an average degree of polymerization of 2000 is used.
(5) Alternatively, only a resin having an average polymerization degree of 1100 of a polymethyl methacrylate homopolymer is used for the base sheet, and 100 parts by weight of a resin having an average polymerization degree of 1100 of the polymethyl methacrylate homopolymer is used for the resin layer. And 100 parts by weight of a vinyl chloride-vinyl acetate copolymer (copolymer having a 90:10 weight ratio and an average degree of polymerization of 700) is used.
(6) Alternatively, the base sheet is made of a resin composed of 90 parts by weight of isotactic polypropylene and 10 parts by weight of atactic polypropylene, and the resin layer is 75 parts by weight of isotactic polypropylene and 25 parts of atactic polypropylene. A resin consisting of parts by weight is used.
[0015]
The present invention will be further described in detail below.
[0016]
[Forming sheet: Base sheet]
A resin sheet having thermoformability is used as the base sheet. Examples of the resin sheet include polypropylene, polyethylene, polybutene, polymethylpentene, ethylene-propylene copolymer, ethylene-propylene-butene copolymer, polyolefin resins such as olefin thermoplastic elastomer, ethylene-isophthalate- Terephthalate copolymer, polyester resin such as polybutylene terephthalate, polyamide resin such as nylon, vinyl chloride resin, acrylic resin, ABS resin (acrylonitrile-butadiene-styrene copolymer), other thermoplastic elastomers such as urethane, etc. A thermoplastic resin sheet is used. Although the thickness of a base material sheet is not specifically limited, Generally, it is about 30-500 micrometers, and is 20-200 micrometers in a transfer type.
In the transfer type, a sheet having releasability from the resin layer is used as the base sheet. For this reason, if necessary, in order to improve the peelability from the resin layer on the resin layer side of the base sheet, a base sheet having a known release layer is provided. The release layer is removed from the transfer layer together with the base sheet when the base sheet is peeled off. For the release layer, for example, silicone resin, wax or the like is used. In addition, a mold release layer is about 0.1-4 micrometers, and the influence on the softening temperature of the whole base material sheet is minute. In the laminate type, a coloring agent such as a dye or a pigment is kneaded into the base sheet resin, and the base sheet may be subjected to a decoration treatment such as colored transparent or colored opaque or colorless opaque.
[0017]
[Sheet for molding: resin layer]
In order to laminate the resin layer on the base material sheet, a film-like material may be attached, or may be laminated by a printing method or a coating method. Although the thickness of a resin layer is made thinner than a base material sheet, it is about 1-100 micrometers normally.
The resin layer is usually laminated by a method such as coating, printing, adhesion of a resin film, or the like by adding a colorant such as a pigment or a dye. When the molding sheet is used for laminating the adherend, the resin layer may be laminated on the side where the molding sheet is in contact with the adherend, or on the opposite side. In the latter case, after the molding sheet is laminated on the adherend, the resin layer can be used as a surface protective layer or the like.
[0018]
As the resin of the resin layer, a resin having thermoformability is used. For example, when the resin is formed by printing or coating, chlorinated polyolefin such as chlorinated polyethylene and chlorinated polypropylene, poly (meth) acrylate, poly (meth) ethyl acrylate, poly (meth) ) Acrylic resins such as butyl acrylate, methyl (meth) acrylate-butyl (meth) acrylate copolymer, methyl (meth) acrylate-styrene copolymer, thermoplastic polyester resin, thermoplastic urethane resin, vinyl acetate A thermoplastic resin such as resin, vinyl chloride-vinyl acetate copolymer, and plasticized cellulose resin is used alone or in combination of two or more. Further, when the resin layer is laminated by adhesion of a resin film, polyolefin resins such as polypropylene, polyethylene, ethylene-propylene copolymer, olefin thermoplastic elastomer, ethylene-isophthalate-terephthalate copolymer, polybutylene. Resins listed as the base sheet such as polyester resin such as terephthalate can be used as long as the relationship between the softening temperature and the thickness is satisfied as described above. Further, a coloring agent such as a pigment may be kneaded into the resin film to make the resin film colored transparent or colored opaque.
[0019]
The resin layer may be formed over the entire surface of the base sheet, or may be partially formed in a pattern. The layer structure may be a single layer, but may also be a decorative layer or an adhesive layer that is laminated two or more layers partially or entirely by printing or coating (see FIG. 1). These may be laminated by a known method. In the case of a decorative layer, for example, printing (or coating) of an ink (or coating liquid) in which various additives such as colorants and extender pigments are further added to a vehicle using the above resin as a binder resin, if necessary. ). The printing may be a known printing method such as gravure printing, offset printing, silk screen printing, or transfer printing from a transfer sheet. The coating may be a known coating method such as roll coating or gravure coating. Examples of the colorant include titanium white, zinc white, petal, vermilion, ultramarine, cobalt blue, titanium yellow, yellow lead, carbon black and other inorganic pigments, isoindolinone, Hansa Yellow A, quinacridone, and permanent red. 4R, phthalocyanine blue, indanthrene blue RS, aniline black and other organic pigments (including dyes), aluminum, brass and other metal pigments, titanium dioxide-coated mica, basic lead carbonate and other foil powders A pearlescent pigment is used.
The pattern of the decoration layer is arbitrary, but there are, for example, a wood grain pattern, a stone pattern, a cloth pattern, a leather pattern, a geometric figure, a character, a symbol, or a solid surface.
[0020]
The adhesive layer is provided as necessary in order to improve the adhesion between the resin layer and the adherend. Examples of the resin used for the adhesive layer include chlorinated polyolefins such as chlorinated polyethylene and chlorinated polypropylene, acrylic resins as described above, polyvinyl chloride, polyvinyl acetate, vinyl chloride-vinyl acetate copolymer, butyral resin, A thermoplastic polyester resin, a thermoplastic urethane resin, a polyamide resin, or a thermoplastic resin such as a polyisoprene rubber, a polyisobutyl rubber, a styrene butadiene rubber, or a butadiene acrylonitrile rubber is used.
[0021]
[Molding method]
As a vacuum forming method (including vacuum / pressure forming) using the forming sheet of the present invention, first, there is a so-called vacuum forming method in which a molded product obtained by vacuum forming of the forming sheet is used as a final formed product. . In addition, the molding sheet is laminated on the adherend using vacuum forming, and in the case of a laminated type molding sheet, the whole molding sheet is laminated as it is on the adherend. In the case of the molding sheet, there is a method in which the base sheet is then peeled to form a molded product in which only the resin layer is laminated on the adherend.
[0022]
(Vacuum forming lamination method)
The first forming method of the present invention is disclosed in Japanese Patent Publication No. 56-45768 (overlay method), Japanese Patent Publication No. 60-58014 (vacuum press method), Japanese Patent Application Laid-Open No. 4-368837 (overlay method and vacuum press). Pressure) by vacuum suction from the adherend side, with a molding sheet placed on or opposite to the surface of the solid adherend as appropriate, with an adhesive interposed between them as necessary. The molding sheet is laminated on the adherend due to the difference, and in the case of transfer, the base sheet is then peeled off and only the resin layer is laminated. Is the method. In the case of transfer, of course, the molding sheet faces or is placed with the resin layer side facing the adherend side.
[0023]
FIG. 2 is an explanatory view of the vacuum press method among the vacuum forming and laminating methods. The vacuum pressing method is similar to the overlay method (vacuum laminating method), but in addition to the pressure difference of air when the molding sheet is pressed against the adherend, the contraction force (contraction pressure) of the rubber-like elastic film as the elastic film ), And the molding sheet is heated through a rubber-like elastic film heated by a heater, and is characterized by uniform heating of the molding sheet and stronger pressing force.
[0024]
The vacuum press apparatus 30 shown in the schematic configuration diagram of FIG. 1 has an upper chamber 11 that can be moved up and down by a vertical movement mechanism 13 such as a fluid pressure cylinder, and the lower chamber 21 faces the upper chamber 11 and faces downward. There is. An infrared radiation type heater 12 is disposed inside the upper chamber 11. The lower opening surface of the upper chamber 11 is entirely covered with a rubber-like elastic film 15. Silicone rubber or the like is usually used for the rubber-like elastic film 15. The lower chamber 21 is a mounting table 22 having a plurality of exhaust holes 23 on the upper surface. The upper chamber 11 and the lower chamber 21 have supply / exhaust ports 14 and 24, respectively, and the internal pressures can be adjusted independently.
In the vacuum press method, first, the adherend W is placed on the table 22 while the upper chamber 11 is moved upward and separated from the lower chamber 21, and the molding sheet S is further placed on the adherend W. To do. At that time, in the case of the transfer type molding sheet S, the resin layer side serving as the transfer layer faces the adherend W. When the adhesive is applied to the outer surface of the molding sheet or the transfer object, it is applied at this stage. If the adhesive contains a solvent, it is dried at this stage.
Next, the upper chamber 11 is moved downward and pressed against the lower chamber 21, and the upper chamber 11 and the lower chamber 21 are sealed. FIG. 2 shows this state. Next, the inside of the lower chamber 21 is depressurized and the inside of the upper chamber 11 is pressurized. Furthermore, the molding sheet S is heated and softened through the rubber-like elastic film 15 using the heater 12 so as to be ready for molding. As a result, the molding sheet S is pressed by the pressure difference of the air between the upper chamber 11 and the lower chamber 21 and the contraction pressure of the rubber-like elastic film 15, and is deformed and pressed along the outer surface of the adherend W. The sheet S adheres to the adherend W and is laminated.
Finally, the decompression of the lower chamber 21 is released, the pressurization of the upper chamber 11 is released, both chambers are brought to atmospheric pressure, the upper chamber 11 is moved upward, and the upper chamber 11 and the lower chamber 21 are separated. The adherend W on which the sheets S are laminated is taken out. In the case of a laminate type molding sheet, the adherend W on which the molding sheet S is laminated becomes a molded product as it is. In the case of a transfer type molding sheet, the base sheet of the molding sheet is further peeled off, leaving only the resin layer as a transfer layer, and a molded product in which the resin layer is laminated on the adherend is obtained.
[0025]
In addition, what is necessary is just to use the adhesive agent which consists of resin etc. which were listed by the adhesive bond layer of the resin layer of the sheet | seat for shaping | molding as this adhesive agent in the case of applying an adhesive agent to the to-be-adhered body side. The adhesive is applied to the adherend by a known coating method such as spray coating.
[0026]
The adherend W is not particularly limited as long as it is a three-dimensional shape. For example, the material of the adherend W can be wood, plastic, inorganic, or metal. Specifically, wood veneer and wood plywood made of various kinds of trees such as cedar, firewood, lawan, particle board, laminated wood, woody material such as wood medium density fiberboard (MDF), polypropylene, ABS resin, phenol resin, etc. Non-ceramic ceramic materials such as calcium silicate, calcium silicate, ALC (lightweight cellular concrete), GRC (glass fiber reinforced concrete), pulp cement, and inorganic materials such as ceramics such as ceramics, porcelain, glass and glaze Or a metal material such as iron, aluminum, or copper.
[0027]
(Injection molding simultaneous painting method)
Further, the second method of the molding method of the present invention is, as described in JP-A-6-315950, JP-B-2-42080, etc., a transfer type molding sheet is formed by both male and female injection molding. After being placed in between, the resin in fluid state is injected and filled into the mold, and simultaneously with the molding of the resin molded product, the resin layer is transferred from the molding sheet to the surface as a transfer layer, so-called simultaneous injection molding applied to the transfer type After placing a laminate type molding sheet between both male and female molds, as described in the painting transfer method, or Japanese Patent Publication No. 50-19132, Japanese Patent Publication No. 43-27488, etc., So-called injection such as the so-called injection molding simultaneous painting laminating method applied to a laminating type, in which a resin in a fluid state is injected and filled into a mold, and a molding sheet is laminated on the surface simultaneously with the molding of a resin molded product Completion A method of using a specific shaping sheet described above simultaneously painting method. In the case of transfer, of course, the molding sheet is arranged with the resin layer side facing the molding resin side. In addition, the molding sheet can be vacuum formed outside before being placed between the molds, but it is easy to cause wrinkles. Therefore, preferably, after the molding sheet is placed between the molds, the injection molding die Is vacuum molded as a vacuum mold, and then the resin is injected.
[0028]
FIG. 3 is a conceptual diagram for explaining the injection molding simultaneous painting lamination method in the injection molding simultaneous painting method. In the present invention, the molding sheet is heated between the molds and softened before clamping, and the injection molding mold is used as a vacuum molding mold and preformed by vacuum molding. Eject.
[0029]
First, as shown in FIG. 3A, as an injection mold, a sheet Ma having a runner communicating with an injection nozzle and a gate (gate), and a suction hole 41 on the mold surface are preformed. A pair of molds of a mold Mb that also serves as a mold is used. The mold is made of metal such as iron or ceramics. In the mold open state, the molding sheet S is fixed to the mold Mb by pressing it with a frame-shaped clamp (not shown). Next, as shown in FIG. 3B, the molding sheet is heated and softened by the heater 42 (in this example, non-contact radiant heating, but contact heating may be used). Then, as shown in FIG. 3C, suction is performed through the suction holes and vacuum forming is performed, and the forming sheet is preformed along the cavity surface of the mold Mb. Note that vacuum forming may be performed by using vacuum / compressed air together with compressed air. Next, both molds are clamped as shown in FIG. 3D, and a resin formed in a fluid state such as a heat-melted state is filled into a cavity formed by both molds as shown in FIG. Then, after the resin is solidified by cooling or the like, the mold is opened, the molded product is taken out, and if there is an unnecessary portion of the molding sheet, trimming is appropriately performed, as shown in FIG. A molded product P having a form in which the molding sheet S is laminated is obtained.
[0030]
As the molding resin to be injection-molded, those known in the conventionally known simultaneous injection molding and painting method can be used and are not particularly limited. For example, if it is a thermoplastic resin, polyolefin resin such as polyethylene and polypropylene, vinyl chloride resin, acrylic resin, ABS (acrylonitrile-butadiene-styrene copolymer) resin, styrene resin, AS (acrylonitrile-styrene copolymer) Resins, polycarbonate resins, and the like, and curable resins include unsaturated polyester resins, curable acrylic resins, two-component curable urethane resins, and epoxy resins.
The thermoplastic resin is injected into a fluidized state by heat melting and cooled and solidified in the cavity, and the thermosetting resin is appropriately heated by injecting the uncured material and injected in a fluidized state and solidified by reaction curing.
[0031]
[Use of molded products]
The use of the molded product obtained in the present invention is not particularly limited and can be used for various purposes. For example, interior materials for buildings such as walls, ceilings and floors, exterior walls such as siding, exterior materials such as fences, roofs, gates, and windbreak boards, window frames, doors, handrails, sills, Application for surface decoration materials, application for surface decoration materials for cabinets of low-power / OA equipment such as furniture for furniture and TV sets, interior decoration materials for vehicles such as automobiles, trains, aircraft, ships, bottles, It can be used for various other containers such as cosmetic containers, various packaging containers and accessories such as small items, and miscellaneous goods such as prizes and accessories.
[0032]
【Example】
Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples.
[0033]
[Reference example1]
  An acrylic resin sheet having a thickness of 125 μm was prepared as a base sheet. The acrylic resin is a resin made of a mixture of methyl methacrylate-butyl methacrylate copolymer and acrylic rubber. Moreover, the softening temperature Tsb of this acrylic resin sheet was 90 degreeC. Then, a decorative layer having a total thickness of 5 μm having a pattern as a resin layer is provided on one side of the base sheet, and a mixed resin (a 1: 1 weight ratio of an acrylic resin and a vinyl chloride-vinyl acetate copolymer) as a binder resin ( Gravure printing and laminating a colored ink composed of a petrol and a color pigment mainly composed of carbon black on a vehicle using a Vicat softening temperature Tsr of 65 ° C.), MatureA form sheet was obtained.
[0034]
The molding sheet is heated for 5 seconds at a position 30 mm away from a ceramic heater heated to 300 ° C., then vacuum-formed, and is 300 mm long, 200 mm wide, 30 mm deep, and a corner radius of curvature of 4 mm. A shaped molded product was obtained. At that time, the temperature of the molding sheet was 90 ° C. No cracks occurred in the stretched portion of the resin layer.
[0035]
[Comparative Example 1]
  Reference example1 except that the resin (binder resin) used in the resin layer is replaced with a resin mainly composed of methyl methacrylate (Vicat softening temperature Tsr is 100 ° C.)Reference example1 to prepare a molding sheet,Reference example1 was vacuum formed. As a result, there was no occurrence of cracks in the resin layer of the part where the molding sheet was not stretched, but in the part where the sheet was stretched by about 60%, there were places where fine cracks occurred in the resin layer, It was inferior in design.
[0036]
[Reference Example 1]
  Reference exampleOn the decorative layer of the resin layer of 1 molding sheet, an adhesive layer having a thickness of 2 μm was further mixed with a mixed resin (Vicat softening temperature) of acrylic resin and vinyl chloride-vinyl acetate copolymer. A molding sheet was prepared in which an ink composed of Ts (65 ° C.) was gravure-printed and laminated to form a resin layer composed of a decorative layer and an adhesive layer. The molding sheet is fixed in an injection mold for molding a resin molded product (adhered body) having a flat application surface, and then clamped and the molten acrylic resin (250 ° C.) is molded at a mold temperature of 70. Injection molding was performed at a temperature of ° C. As a result, a molded product in which the molding sheet was laminated on the adherend with good adhesion was obtained. Of course, since the molding sheet was not stretched, no crack was generated in the resin layer.
[0037]
[Reference Example 2]
In Reference Example 1, the molding sheet is laminated in the same manner as in Reference Example 1 except that the resin of the adhesive layer is replaced with an acrylic resin mainly composed of polymethyl methacrylate (Vicat softening temperature Ts is 100 ° C.). A molded product was obtained. As a result, a molded product in which the molding sheet was laminated on the adherend with good adhesion was obtained. Of course, since the molding sheet was not stretched, no crack was generated in the resin layer.
[0038]
〔Example1]
  Using the molding sheet used in Reference Example 1, this time, the shape of the resin molding (adhered body) as an injection mold is 300 mm in length, 200 mm in width, 30 mm in the depth direction, and the radius of curvature at the corner is 4 mm. Simultaneous injection painting was performed using a box mold. After fixing the molding sheet to the mold, the sheet was heated to 90 ° C. with a heater, and then the mold was evacuated and vacuum molded to fit along the cavity surface of the female mold. Next, the mold was clamped and melted acrylic resin (250 ° C.) was injection-molded at a mold temperature of 70 ° C. As a result, a molded product in which the molding sheet was laminated with good adhesion to the adherend of the resin molded product was obtained. Further, no crack was generated in the resin layer even at the place where the molding sheet was stretched at the corner. In addition, in the molding sheet on the molded product, a grid-like cut at 1 mm intervals in both the vertical and horizontal directions reaching the resin molded product is made, and the cellophane adhesive tape (manufactured by Nichiban Co., Ltd., “Cello Tape” (registered trademark)) is provided on the surface. After the 24 mm width, industrial) was pasted at 25 ° C., it was peeled off vigorously, and a cross cut test was conducted. As a result, the molding sheet did not peel off.
[0039]
[Comparative Example 2]
  Using the molding sheet used in Reference Example 2,Reference exampleIn the same manner as in No. 1, a molded product was obtained. As a result, the molding sheet is stretched at the corner and the adhesion at the place is poor, and the molding sheet on the molded product is cut into grid-like cuts at 1 mm intervals both vertically and horizontally to reach the resin molded product. A cellophane adhesive tape (manufactured by Nichiban Co., Ltd., “Cellotape” (registered trademark) 24 mm width, industrial use) was attached at 25 ° C. and then peeled off vigorously. It has come off.
[0040]
【The invention's effect】
(1) According to the molding sheet of the present invention, since the thickness and softening temperature between the base sheet and the resin layer have a specific relationship, when the molding sheet is vacuum molded, cracks in the resin layer occur. Does not occur. Therefore, the appearance defect due to the occurrence of cracks and the adhesion failure with the adherend when the resin layer is used as the adhesive layer do not occur.
(2) Further, according to the molding method of the present invention, by using the molding sheet, the appearance failure due to the occurrence of cracks in the resin layer, and the adherend when the resin layer is used as an adhesive layer, There is no adhesion failure. In the vacuum forming lamination method, a molding sheet can be applied to an adherend having a shape. In the injection molding simultaneous painting method, the molding sheet can be applied simultaneously with the forming of the adherend.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view illustrating one embodiment of a molding sheet of the present invention.
FIG. 2 is an explanatory view of a vacuum forming and laminating method using a vacuum press as an embodiment of the forming method of the present invention.
FIG. 3 is an explanatory view of a laminate type injection molding simultaneous painting method as one embodiment of the molding method of the present invention.
[Explanation of symbols]
1 decoration layer
2 Adhesive layer
11 Upper room
12 Heater
13 Vertical movement mechanism
14, 24 Intake / exhaust port
15 Rubber elastic membrane
21 lower chamber
22 table
23 Exhaust hole
30 Vacuum press equipment
41 Suction hole
42 Heater
B Base sheet
Db Base sheet thickness
Dr resin layer thickness
Ma injection mold (male mold)
Mb injection mold (female)
P Molded product
R resin layer
S sheet for molding
Softening temperature of Tsb substrate sheet
Softening temperature of Tsr resin layer
W adherend

Claims

In a molding sheet comprising a base sheet and at least one resin layer laminated on the base sheet and thinner than the base sheet,
The base sheet is made of acrylic resin,
The resin layer is chlorinated polyolefin, acrylic resin, polyvinyl chloride, polyvinyl acetate, vinyl chloride-vinyl acetate copolymer, butyral resin, thermoplastic polyester resin, thermoplastic urethane resin, polyamide resin, or rubber resin. Including an adhesive layer using a thermoplastic resin of
The molding sheet in which the softening temperature Tsr of all the resin layers including the adhesive layer is Tsr ≦ Tsb with respect to the softening temperature Tsb of the base sheet.

The molding sheet according to claim 1 is opposed or placed with respect to the surface of the three-dimensional adherend via the adhesive layer, and the pressure difference between the front and back sides of the molding sheet is at least from the adherend side. In the case of lamination, the entire layer of the molding sheet is directly applied to the adherend. A forming method by a vacuum forming lamination method in which a laminated molded product is used, and in the case of transfer, a base material sheet is then peeled and only a resin layer is laminated on an adherend.

The molding sheet according to claim 1 is inserted between a pair of molds, and the mold is vacuum-molded as a vacuum-molding mold. Then, both molds are clamped, and in a fluid state in a cavity formed by both molds. After the resin is filled and the molding sheet is adhered and laminated to the surface of the molded product at the same time as molding, both molds are opened, and in the case of lamination, the entire molding sheet layer is taken directly from the resin molding. Injection molding simultaneous painting method, in which in the case of transfer, the base sheet is further peeled off and the resin layer is laminated on the adherend consisting of a resin molded product. Molding method by.