JP4043762B2 - Decorative sheet and decorative molded product - Google Patents

Description

【００２０】
なお、透明基材シートに用いる前記熱可塑性樹脂としては、用途に応じて要求される透明性、成形性等を満足するものであれば、特に制限は無い。例えば、例えば、ポリメチル（メタ）アクリレート、ポリブチル（メタ）アクリレート、メチル（メタ）アクリレート−ブチル（メタ）アクリレート共重合体、メチル（メタ）アクリレート−スチレン共重合体等のアクリル樹脂〔但し、（メタ）アクリレートとは、アクリレート又はメタクリレートの意味。以下同様。〕、ポリエチレン、ポリプロピレン、ポリメチルペンテン、ポリブテン、アイオノマー、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、ポリブチレンテレフタレート、ポリエステル系熱可塑性エラストマー、完全非晶質ポリエステル等のポリエステル樹脂、ポリスチレン、アクリロニトリル−スチレン共重合体等のスチレン系樹脂、塩化ビニル樹脂、塩化ビニリデン樹脂、酢酸ビニル−塩化ビニル共重合体、ポリビニルブチラール等のビニル系樹脂、ポリフッ化ビニル、ポリフッ化ビニリデン、エチレン−４フッ化エチレン共重合体等のフッ素樹脂、ナイロン６、ナイロン６６等のポリアミド樹脂、ポリカーボネート樹脂等である。透明基材シートには、これら樹脂のシート（フィルム）の単層又は２層以上の積層体が用いられる。なお、透明基材シートの厚さは、通常５０〜１５０μｍ程度である。
【００２１】
また、透明基材シート中には、透明性に支障を来さない範囲内で、必要に応じて適宜、着色剤、減摩剤、滑剤、酸化防止剤、光安定剤、可塑剤、帯電防止剤、防黴剤、抗菌剤、難燃剤等の添加剤を添加する。なお、これら各種添加剤としては、用途に応じた公知の添加剤を使用することができる。
【００２２】
例えば、特に、耐候（光）性が要求される用途では、光安定剤として、ベンゾトリアゾール系、ベンゾフェノン系、サリチル酸エステル系等の有機物の紫外線吸収剤や、粒径０．２μｍ以下の微粒子状の酸化亜鉛、酸化セリウム、酸化チタン等の無機物の紫外線吸収剤、ヒンダードアミン系ラジカル捕捉剤、ピペリジン系ラジカル捕捉剤等のラジカル捕捉剤の添加が好ましい。添加量は、通常両者ともに各々０．１〜５質量％の範囲である。
【００２３】
また、透明基材シートと透明平滑化塗膜との密着性向上が必要な場合には、コロナ放電処理、プラズマ処理、オゾン処理等の表面処理や、プライマー層形成等の公知の易接着処理を施しても良い。プライマー層にはシランカップリング剤等が使用される。
【００２４】
〔透明平滑化塗膜〕
透明平滑化塗膜２は、上述の如きフィッシュアイ状凹凸を平滑化する為の塗膜であるが、透明基材シート裏面側に形成する絵柄インキ層を透視できる様に透明な塗膜とする。塗膜を、透明な塗膜とし且つフッシュアイ状凹凸を平滑化できる様な塗膜とするには、透明平滑化塗膜は透明樹脂で形成すると良い。
【００２５】
上記透明樹脂としては、透明性を満足すれば特に制限は無いが、例えば、アクリル樹脂、ウレタン樹脂、塩化ビニル−酢酸ビニル共重合体、塩素化ポリプロピレン、ポリエステル樹脂等の１種又は２種以上の混合物を、透明基材シートと絵柄インキ層の材料に応じ、これら両層との密着性等を考慮して、適宜選択すれば良い。
【００２６】
なお、上記アクリル樹脂としては、例えば、ポリメチル（メタ）アクリレート、ポリブチル（メタ）アクリレート、メチル（メタ）アクリレート−ブチル（メタ）アクリレート共重合体、メチル（メタ）アクリレート−スチレン共重合体等のアクリル樹脂、或いは、メチル（メタ）アクリレート、エチル（メタ）アクリレート、ブチル（メタ）アクリレート、オクチル（メタ）アクリレート、シクロヘキシル（メタ）アクリレート等と、２−ヒドロキシエチル（メタ）アクリレート、２−ヒドロキシ−３−フェノキシプロピル（メタ）アクリレート等の分子中に水酸基を有する（メタ）アクリル酸エステルとを共重合させて得られるアクリルポリオール等のアクリル樹脂を、単体又は２種以上混合して使用する。
【００２７】
なお、上記ウレタン樹脂としては、２液硬化型ウレタン樹脂、熱可塑性ウレタン樹脂等が用いられる。２液硬化型ウレタン樹脂は、ポリオールを主剤とし、多価イソシアネートを架橋剤とする。ポリオールとしては、アクリルポリオール、ポリエステルポリオール、ポリカーボネートポリオール、ポリエーテルポリオール、ポリウレタンポリオール等が、また、多価イソシアネートとしては、２，４−トリレンジイソシアネート、キシレンジイソシアネート、ジフェニルメタン−４，４′−ジイソシアネート等の芳香族イソシアネート、１，６−ヘキサメチレンジイソシアネート、イソホロンジイソシアネート、水素添加トリレンジイソシアネート等の脂肪族（乃至は脂環式）イソシアネートが用いられる。或いは、イソシアネートとしては、これらイソシアネートの多量体、又は付加体を用いても良い。
【００２８】
透明平滑化塗膜の形成は、好ましくは１工程で形成する。すなわち、１工程で形成した単層の塗膜が好ましい。その理由は、薄膜の塗り重ねで厚みを増すと、透明基材シート裏面のフィッシュアイ状凹凸の凹凸形状を拾い、しかもそれが積み重なるので、インキ抜けを解消出来ないからである。図４の断面図は、この多工程による塗り重ねで、複層構成で厚みを増した塗膜６の状況を、概念的に示した図である。図４（Ａ）に示す如く、裏面にフィッシュアイ状凹凸Ｆを有する透明基材シート１の該裏面に対して、順次、第１層６ａ〔図４（Ｂ）〕、第２層６ｂ〔図４（Ｃ）〕、第３層６ｃ〔図４（Ｄ）〕と、塗膜を重ね塗りして３層構成の塗膜６を形成しても、前記凹凸Ｆが解消し平坦化されない状況を示す。
【００２９】
これに対して、図５（Ａ）及び（Ｂ）の断面図で概念的に示す如く、塗膜を１工程で厚膜で塗り、第１層６ａのみで凹部の充填を行えば、フィッシュアイ状の凹凸Ｆの凸部の高さを低くし、以って、被印刷面を平滑化でき、インキ抜けは解消できる。従って、前記第１層６ａは、透明平滑化塗膜２に好適な塗膜となる。
【００３０】
なお、透明平滑化塗膜による平滑化の程度は、透明基材シートの裏面のフィッシュアイ状の凹凸を完全に平滑化（平坦化）することが理想ではあるが、実用上は、透明基材シート裏面が持つ凹凸の高低差よりも、塗工後の（塗工面の）凹凸の高低差が低減され、インキ抜けが実用上支障無い程度（平均１個／加飾成形品１個の加飾面積）となれば十分である。
【００３１】
なお、透明平滑化塗膜としては、１工程の塗工による単層の塗膜が好ましいものであるが、この様な塗膜を形成する為の塗工法としては、フィッシュアイ状凹凸の高低差をインキ抜けが実用上改善できる厚みに塗工できる方法であれば特に制限はない。例えば、グラビアリバースコート、ロールコート、コンマコート等の一回の塗工で２μｍ以上の塗膜厚を形成できる塗工法が好ましい。
【００３２】
〔絵柄インキ層〕
絵柄インキ層３は、インキ（或いは塗液）を用いて、グラビア印刷、活版印刷、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、インキジェット印刷等公知の印刷法、或いは手描き法等の従来公知の形成法によって形成することができる。絵柄インキ層は、全面（全ベタ層）に、或いは所望のパターン状（柄パターン層）に部分的に形成する。なお、全面に形成する場合には、グラビアコート、ロールコート等の従来公知の塗工法を用いて形成することもできる。
【００３３】
なお、絵柄インキ層の形成（印刷や塗工等）に用いるインキは、通常、バインダー等からなるビヒクル、顔料や染料等の着色剤、これに適宜加える各種添加剤からなるが、バインダーの樹脂には、アクリル樹脂、塩化ビニル−酢酸ビニル共重合体、塩素化ポリプロピレン、ポリエステル樹脂、セルロース系樹脂、ウレタン樹脂等の単体又は混合物が用いられる。なお、上記アクリル樹脂やウレタン樹脂としては、例えば、前述した透明平滑化塗膜で列記した如き樹脂が使用できる。
【００３４】
なお、上記着色剤としては、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、鉄黒等の無機顔料、イソインドリノンイエロー、ベンジジンイエロー、キナクリドンレッド、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）等の公知の着色剤を使用できる。
【００３５】
なお、絵柄インキ層で表現する絵柄は、例えば、木目模様、石目模様、砂目模様、布目模様、タイル貼模様、煉瓦積模様、皮絞模様、幾何学模様、文字、記号、全面ベタ等が、用途に合わせて、１種又は２種以上組み合わせて使用される。
【００３６】
〔接着剤層〕
加飾シートの裏面側は、必要に応じ適宜、被着体である射出成形物との接着性を向上させるために、コロナ放電処理、プラズマ処理、プライマー塗工等の易接着処理の他、これら易接着処理を処理後或いは処理せずに、接着剤層４を設けても良い。
接着剤層４を設ける事により、射出成形物との密着性向上が容易となり、射出成形物の材料選択の幅が広がる。その結果、射出成形物材料の点でもコストダウンを行い易くなる。
【００３７】
接着剤層４としては、被着体材料に応じて、例えば感熱型の接着剤として熱可塑性樹脂、熱硬化性樹脂等の公知の樹脂が用いられる。熱可塑性樹脂では、例えば、酢酸ビニル樹脂、塩化ビニル−酢酸ビニル共重合体、アクリル樹脂、熱可塑性ポリエステル樹脂、ポリアミド樹脂、アイオノマー、塩素化ポリオレフィン樹脂、熱可塑性ウレタン樹脂、ゴム系樹脂等の１種又は２種以上の混合物が用いられる。また、熱硬化性樹脂では、フェノール樹脂、ブロックイソシアネート硬化型等のウレタン樹脂、エポキシ樹脂等が用いられる。
接着剤層は、これら樹脂による接着剤を、グラビア印刷、ロールコート等の公知の印刷又は塗工法により形成する。また、接着剤層の厚さは特に制限は無いが、通常は１〜１００μｍ程度である。
【００３８】
加飾成形品：
本発明の加飾成形品は、図２の断面図でその一形態を例示した如く、上記本発明の加飾シートＳが、その透明基材シート１に対して絵柄インキ層３側を射出成形物５側を向く様にして樹脂成形物５の表面に積層された構成の成形品である。つまり、同図に例示の本発明の加飾成形品Ｐは、射出成形物５上に、順次、接着剤層４、絵柄インキ層３、透明平滑化塗膜２、及び透明基材シート１が積層され、該透明基材シート１の射出成形物５側である裏面に存在するフィッシュアイ状の凹凸Ｆは、透明平滑化塗膜２によって平坦化された構成の成形品である。なお、接着剤層４は省略される形態もある。
なお、射出成形物５上への加飾シートＳの積層は、好適には射出成形同時加飾方法によって行える。
【００３９】
〔射出成形物〕
射出成形物５の樹脂としては、基本的には特に制限はなく公知の樹脂で良い。製品の要求物性やコスト等に応じて選定すれば良い。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、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、或いは、ＡＢＳ（アクリロニトリル−ブタジエン−スチレン共重合体）樹脂、ＡＳ（アクリロニトリル−スチレン共重合体）樹脂、スチレン樹脂、アクリル樹脂、塩化ビニル樹脂、ポリカーボネート樹脂等である。また、硬化性樹脂であれば、２液硬化型の樹脂、例えば、ウレタン樹脂、不飽和ポリエステル樹脂、エポキシ樹脂等の未硬化樹脂液等である。熱可塑性樹脂は加熱熔融して流動状態で射出し、また硬化性樹脂は（その未硬化物を）室温又は適宜加熱して流動状態で射出する。
【００４０】
なお、樹脂中には、用途に応じて適宜、着色剤を添加して着色した樹脂を使用しても良い。着色剤には、前述絵柄インキ層で述べた如き公知の着色剤を使用すれば良い。また、樹脂中には、必要に応じ適宜、シリカ、アルミナ、タルク、炭酸カルシウム、水酸化アルミニウム等の無機物粉末、ガラス繊維等の充填剤、安定剤、滑剤、エラストマー等の公知の各種添加剤を含有させる。
【００４１】
〔成形品形状〕
なお、加飾成形品は、通常、加飾シートの積層面が凹凸面等と非平面の立体物である。しかし、本発明の加飾成形品としては、加用シートの積層面は平面だが他の面が非平面の立体物、積層面が平面となる板状物を排除するものではない。
【００４２】
加飾成形品の製法：
なお、本発明の加飾成形品を得るには、前記本発明の加飾シートを使用すれば得られ、またその際の、加飾シートを射出成形物に積層する方法としては、後述する射出成形同時加飾方法が好適である。しかし、本発明の加飾成形品を得る方法は、この射出成形同時加飾方法に必ずしも限定されるものでは無い。被着体となる射出成形物（に於ける加飾シートの被着面の形状）、用意できる製造設備等に応じて、適宜他の積層方法を採用しても良い。例えば、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）等に記載の所謂真空成形積層方法、特公昭６１−５８９５号公報、特公昭５６−２３７７１号公報等に記載の所謂ラッピング加工方法等でも良い。但しもちろん、射出成形同時加飾方法で積層するのが、射出成形物の成形と、その加飾とを同時に１工程で出来、生産効率も良い等の点で好ましい。
【００４３】
〔射出成形同時加飾方法〕
次に、上記の中でも、特に射出成形同時加飾方法ついて更に詳述する。射出成形同時加飾方法としては、大別して積層形態と転写形態とがあるが、本発明に於いて採用し得る方法は、積層形態の方である。積層形態の射出成形同時加飾方法は、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、加飾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、射出成形物の成形と同時にその表面に加飾シートを積層して加飾する方法である。
【００４４】
射出成形同時加飾方法では、加飾シートの予熱無しの場合でも、射出樹脂による熱圧を加飾シートが受ける。従って、加飾シートの予備成形は、行う形態でも行わない形態でも、いずれでも良い。また、加飾シートの予熱は、行っても良く、行わなくても良い。なお、予備成形時には通常は加飾シートは予熱する。
【００４５】
なお、もちろんの事だが、加飾シートの絞りが大きい場合は、予備成形を行うのが好ましい。一方、加飾シートの絞りが少ない場合は、射出される流動状態の樹脂の樹脂圧と樹脂熱で加飾シートを成形しても良い。この際、絞りが浅ければ、予備成形無しで樹脂射出と同時に型内に充填される流動状態の樹脂の樹脂圧と樹脂熱のみで加飾シートを成形しても良い。また、樹脂圧と樹脂熱で加飾シートを成形する場合でも、加飾シートの加熱は射出樹脂の樹脂熱のみを利用し予熱はしない事もある。また、加飾シートの予備成形は、通常は、射出成形型を真空成形型と兼用して行うが、型間に加飾シートを供給する前に、射出成形型外部で別の真空成形型で加飾シートを真空成形する様な予備成形（オフライン予備成形）でも良い。但し、予備成形は、射出成形型と真空成形型とを兼用して行う形態が効率的且つ精度良く加飾シートを積層できる点で好ましい。しかし、予備成形済みの加飾シートを予め別の場所で纏めて製造しておく場合等では、予備成形はオフライン予備成形の形態が好ましい。なお、本発明の説明に於いて真空成形とは真空圧空成形も包含する。
【００４６】
図６の概念図によって、射出成形同時加飾方法を、その或る一形態で説明する。なお、ここで説明する形態は、型締めする前に、加飾シートを型間で加熱し軟化させて射出成形型で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形態である。
また、この形態は、上記した加飾シートの予備成形、予熱の各種組合わせ形態の中で、加飾シートの絞りが深い場合に、より好ましい形態である。
【００４７】
先ず、図６（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（雄型）Ｍａと、キャビティ面に吸引孔４１を有しシートの予備成形型を兼用する型（雌型）Ｍｂの一対の成形型を用いる。これらの型は鉄等の金属、或いはセラミックスからなる。型開き状態に於いて両型Ｍａ、Ｍｂ間に加飾シートＳを供給し、型Ｍｂに加飾シートＳを平面視枠状のシートクランプ４２で押圧する等して固定する。この際、（透明基材シートに対して）絵柄インキ層側は、図面右側の射出樹脂側となる様にする事はもちろんである。次いで、図６(Ｂ)の如く、型外部（図面では型上方）の退避位置で退避させておいたヒータ４３を、適宜移動させて両型間に挿入し、ヒータ４３で加飾シートを加熱軟化させる。加熱は例えば非接触の輻射加熱とするが、接触による伝導加熱でも良い。そして、吸引孔から吸引して真空成形して、加飾シートを型Ｍｂのキャビティ面に沿わせ予備成形する。次いで、ヒータ４３を両型間から型外部の退避位置まで退避させ、図６（Ｃ）の如く両型を型締めし、両型で形成され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、樹脂が冷却等によって固化した後、型開きして成形物を取り出し、加飾シートの不要部分があれば適宜トリミングする事で、加飾成形品が得られる。
【００４８】
【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。
【００４９】
〔実施例１〕
図１の如き構成の加飾シートＳを次の様にして作製した。先ず、透明基材シート１として、無着色の透明アクリル樹脂からなる厚さ１２５μｍの樹脂シートを用意した。そして、この透明基材シートの裏側とする面に、アクリル樹脂と塩化ビニル−酢酸ビニル共重合体との５対５質量比の混合物からなる透明塗液を、グラビアリバース法によって厚さ３μｍ（乾燥時、以下同様）となる様に一回塗工し、透明平滑化塗膜２を形成した。なお、塗工には、スクリーン線数９５Ｌ／ｃｍ、版深９５μｍの版を用いた。
【００５０】
更に、透明平滑化塗膜２側の面に対して、絵柄インキ層３を形成した。絵柄インキ層３は、アクリル樹脂と塩化ビニル−酢酸ビニル共重合体との５対５質量比の混合物をバインダー樹脂とし、着色剤として着色顔料を添加して成る着色インキを用いて、３色重ね刷りのグラビア印刷法で、木目柄の意匠を持つ層として形成した。
【００５１】
更に、絵柄インキ層３側の面に、塩化ビニル−酢酸ビニル共重合体からなる塗液を、スクリーン線数４０Ｌ／ｃｍの版を用いたグラビアリバース法による２回の塗工で、厚さ２μｍの接着剤層４を形成して、所望の加飾シートＳを得た。
【００５２】
そして、図６の概念図に示した様な方式による射出成形同時加飾方法によって、上記加飾シートを射出成形物の成形と同時にその表面に積層して、図２の部分断面図で示す如き構成で、射出成形物５の表面に加飾シートＳが積層された、所望の加飾成形品Ｐを作製した。
【００５３】
なお、射出成形同時加飾は、次の様にして行った。先ず、連続帯状の加飾シートの巻取ロールを、射出成形同時加飾装置のシート送り装置に装着し、型開き状態の雌雄両型間に、加飾シートを１ショット分送り出した。なお、加飾シートは（その透明基材シートに対して）絵柄インキ層側が雄型側を向く様にして、雌雄両型間に供給した。そして、雌型に設置してあるシートクランプ４２を閉じて、雌型パーティング面とシートクランプ間に供給された加飾シートを、雌型パーティング面に固定した。なお、シートクランプに対応する雌型パーティング面部分には、雌型キャビティ全周にわたって溝が設けてあり、該溝中にゴム製のＯリングを埋め込み、このＯリングによって、シートクランプで押圧された加飾シートと雌型パーティング面間に隙間が出来てエアが漏れるのを防ぐ構造となっている。
【００５４】
その後、型外部の退避位置で待機させておいた赤外線輻射加熱方式のパネル状ヒータ４３を、雌雄両型間に挿入して、加飾シートを１３０℃まで加熱して軟化させた。その後、ヒータで加飾シートを加熱しながら、雌型キャビティ面に設けた溝状の吸引孔４１より真空引きを行った。この真空成形により、加飾シートは雌型キャビティの形状に予備成形された。その後、ヒータは型内部から型外部の退避位置に退避させて、雌雄両型を型締めした。
【００５５】
そして、耐熱ＡＢＳ樹脂を雄型のゲートから射出し、射出成形物の成形と同時に加飾シートをその表面に積層一体化して、加飾成形品を成形した。
なお、射出成形条件は、射出樹脂温度は２３０℃、ホットランナはマニホールド部温度が２４０℃でゲート部温度が２３５℃、金型は雌型が３５℃で雄型が４５℃、射出時間は５ｓ、冷却時間は２０ｓである。そして、型開き後、加飾成形品は自動製品取出し装置にて型上から取出した。なお、加飾成形品の加飾面の面積は約２５０ｃｍ²である。
【００５６】
〔比較例１〕
実施例１に於いて、加飾シート作製時に透明平滑化塗膜の形成を省略して、透明基材シートに直接、絵柄インキ層を形成した他は、実施例１と同様にして加飾シート及び加飾成形品を作製した。
【００５７】
〔性能評価〕
透明基材シートの（状態での）フィッシュアイの状況と、得られた加飾シートのインキ抜けの発生状況について評価した。
インキ抜けは外観不良の原因となる面積０．５ｍｍ²以上のものが、１ｍ²当たりの換算で、比較例１では１６個／ｍ²であったが、実施例１では５個／ｍ²に減少した。従って、通常の加飾成形品の寸法（加飾面積）は、０．１ｍ²以下が多い為、成形品１個当たりに相当する（通常の最大）面積０．１ｍ²当たりのインキ抜けの個数で評価すると、比較例１の如く透明平滑化塗膜を設け無い構成では、面積０．１ｍ²内に２個入る確率が相当高くなり品質が安定した量産は難しい。しかし、実施例１の如く透明平滑化塗膜を設けた構成とすれば、面積０．１ｍ²内、つまり成形品１個当たり０．５個〜１個となり、ほぼ品質的に安定して量産可能となった。その結果、透明平滑化塗膜を設ける事で、たとえ１工程増えても、不良品が減るので結果的にコストダウンが図れた。
【００５８】
【発明の効果】
（１）本発明の加飾シートによれば、使用する透明基材シートにフィッシュアイ状凹凸があっても、それによるインキ抜け発生を防げる。しかも、その為に設ける透明平滑化塗膜は、透明な層なので、絵柄インキ層の色調及び可視性にも悪影響しない。この結果、従来ならば、フィッシュアイ状凹凸によって表面平滑性が悪くて採用できかなった様な透明基材シートでも、インキ抜け欠点を安定して防げる。この為、透明基材シート選択の幅が広がり、コストダウンを行い易く、また、成形性をより重視した透明基材シートの選択も可能となるので、加飾成形品の形状対応の幅も広げられる。
（２）更に、接着剤層も積層した構成とすれば、射出成形物との密着性向上が容易となり、射出成形物の材料選択の幅が広がる。その結果、射出成形物材料の点でもコストダウンを行い易くなる。
（３）また、本発明の加飾成形品によれば、上記本発明の加飾シートによる効果が得られ、その結果、フィッシュアイ状凹凸によるインキ抜け発生を防げ、従来ならば、フィッシュアイ状凹凸によって表面平滑性が悪くインキ抜けが発生して採用できかなった様な透明基材シートでも採用できる。この為、透明基材シート選択の幅が広がり、コストダウンや成形性をより重視した選択も可能となり、加飾成形品の形状対応の幅も広げられる。
【図面の簡単な説明】
【図１】本発明の加飾シートの一形態を例示する断面図。
【図２】本発明の加飾成形品の一形態を例示する断面図。
【図３】シート裏面の凹凸によるインキ抜け発生を概念的に説明する断面図と平面図。
【図４】透明平滑化塗膜の重ね塗り時の不具合を概念的に説明する概念図。
【図５】透明平滑化塗膜の一回塗り時の出来具合を概念的に説明する概念図。
【図６】射出成形同時加飾方法をその一例で説明する概念図。
【符号の説明】
１ 透明基材シート
２ 透明平滑化塗膜
３ 絵柄インキ層
４ 接着剤層
５ 射出成形物
６ 塗膜
６ａ （塗膜の）第１層
６ｂ （塗膜の）第２層
６ｃ （塗膜の）第３層
４１ 吸引孔
４２ シートクランプ
４３ ヒータ
Ｆ フィッシュアイ状の凹凸
Ｋ インキ抜け
Ｍａ 射出成形型（雄型）
Ｍｂ 射出成形型（雌型）
Ｐ 加飾成形品
Ｓ 加飾シート[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a laminate-type decorative sheet used in an injection molding simultaneous decorating method and a decorative molded product decorated using the decorative sheet.
[0002]
[Prior art]
In the simultaneous injection molding method (see Japanese Patent Publication No. 50-19132, Japanese Patent Publication No. 43-27488, etc.), simultaneously with the molding of the injection molded article, a decorative sheet is laminated on the three-dimensional surface, Is used in various applications such as automobile interiors. And, in order to obtain a high-class feeling of painting, the decorative sheet is a laminate type, and a pattern ink layer is provided on the back side of the transparent base sheet made of acrylic resin having excellent transparency as the base sheet. Often used as a decorative sheet with a printed configuration.
[0003]
[Problems to be solved by the invention]
However, if the printing surface of the transparent base sheet has fish-eye irregularities due to unmelted resin raw materials or mixed foreign substances, the formation of the pattern ink layer at that portion becomes incomplete, and the cross-sectional view of FIG. In addition, as conceptually shown in the plan view, the ink loss K easily occurs due to the unevenness F. 3A is a cross-sectional view, and FIG. 3B is a plan view when the decorative sheet is viewed from the back side.
Such ink omission is obtained by printing a pattern ink layer on a resin sheet having a good surface property to prepare a transfer sheet, and then applying the pattern ink layer from the transfer sheet to the transparent substrate sheet by sufficient heating and pressurization. If the decorative sheet is prepared by crushing and flattening the unevenness and performing thermal transfer, it can be solved. However, in order to produce one sheet, two types of sheets (transfer sheet and decorative sheet) must be produced, which is not desirable in terms of process and cost.
[0004]
That is, the problem of the present invention is that the injection molding simultaneous decorating technique for laminating the decorative sheet causes the occurrence of ink loss even if the surface of the transparent substrate sheet used for the decorative sheet has fish-like irregularities. Is to prevent.
[0005]
[Means for Solving the Problems]
Therefore, in order to solve the above-described problems, the decorative sheet of the present invention is formed by sequentially smoothing and flattening the unevenness on the back surface of the transparent substrate sheet having fisheye unevenness on at least the back surface. And a single-layer coating formed by one-step coating. A transparent smoothing coating film and a pattern ink layer are laminated for injection molding simultaneous decoration. Laminate type A decorative sheet was used.
[0006]
By adopting such a configuration, even if the transparent base sheet has fish-eye irregularities, the irregularities are smoothed by the transparent smoothing coating film, so that it is possible to prevent ink loss generated by the irregularities. . Moreover, since the transparent smoothing coating film is a transparent layer, it does not adversely affect the color tone and visibility of the pattern ink layer. As a result, it is possible to stably prevent the ink loss defect even in the case of a transparent base sheet that cannot be adopted due to poor surface smoothness due to fish-eye unevenness. For this reason, the range of selection of the transparent base sheet is widened, it is easy to reduce the cost, and selection with more emphasis on formability is possible, so that the width corresponding to the shape of the decorative molded product can be expanded.
[0007]
In addition, the decorative sheet of the present invention has a configuration in which an adhesive layer is further laminated on the back of the pattern ink layer in the above configuration.
[0008]
By adopting such a configuration, it is easy to improve the adhesion to the injection molded product, and the range of material selection for the injection molded product is widened. As a result, the cost can be easily reduced in terms of the injection molded material.
[0009]
In addition, the decorative molded product of the present invention is laminated on the surface of the injection-molded product so that any one of the above-described decorative sheets is directed to the injection-molded product side with respect to the transparent substrate sheet. It was set as the structure comprised.
[0010]
By setting it as such a structure, the effect by the above-mentioned decorating sheet is acquired in a decorating molded product. In other words, it is possible to prevent ink omission defects due to fish-eye irregularities, and to prevent ink omission defects stably even with transparent substrate sheets that have been poorly adopted due to the fish-eye irregularities. For this reason, the range of selection of the transparent base sheet is widened, it is easy to reduce the cost, and selection with more emphasis on formability is possible, and the width corresponding to the shape of the decorative molded product is also widened.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0012]
Overview :
FIG. 1 is a cross-sectional view illustrating an embodiment of a decorative sheet S for simultaneous injection molding according to the present invention. As shown in the figure, in the decorative sheet S of the present invention, the transparent base sheet 1 has fish-eye irregularities F on its back surface. And the transparent smoothing coating film 2 which smoothes and planarizes the unevenness | corrugation F is laminated | stacked on the back surface of this transparent base material sheet 1, and the pattern ink layer 3 is laminated | stacked on the back surface of this transparent smoothing coating film 2. FIG. The pattern ink layer is often used in combination with a pattern pattern layer expressing a pattern-like pattern and a concealing all-solid layer provided on the back side thereof. In addition, in the decorative sheet S illustrated in the figure, an adhesive layer 4 is further laminated on the back surface of the pattern ink layer 3.
By having such a configuration, the pattern ink layer is formed with a concave portion of fish-eye irregularities on the back surface of the transparent base sheet by a transparent transparent smoothing film that does not affect the color tone and visibility of the pattern ink layer. Since it is formed after filling and smoothing, a pattern ink layer without ink loss can be obtained.
[0013]
And the decorative sheet S of the present invention as illustrated in the cross-sectional view of FIG. 2 is obtained by laminating the decorative sheet S of the present invention as described above on the surface of the injection molded product. That is, the decorative sheet S having the above-described configuration is a decorative molded product P having a configuration in which the pattern ink layer 3 side is directed to the injection-molded product side with respect to the transparent base sheet 1, On the molded product 5, the adhesive layer 4, the pattern ink layer 3, the transparent smoothing coating film 2, and the transparent base material sheet 1 are sequentially laminated, and the injection molded product 5 side that is the back surface of the transparent base material sheet 1. Is a molded article having a structure in which the fisheye-like irregularities F existing on the back surface of the transparent base sheet 1 are flattened by the transparent smoothing coating film 2.
[0014]
Decorative sheet :
Next, a transparent base material sheet, a transparent smoothing coating film, a pattern ink layer, an adhesive layer, and the like, which are constituent elements of the decorative sheet, will be described.
[0015]
[Transparent substrate sheet]
As the transparent base sheet 1, a transparent resin sheet is used. The term “transparent” refers to transparency that allows the pattern ink layer to be seen through (or more), and may be colored and transparent as well as colorless and transparent. And as resin of this resin sheet, as resin which can be shape | molded at the time of decorating sheet use, Preferably resin from which a moldability is obtained is used. Therefore, as the resin of the resin sheet, a thermoplastic resin is preferably used in terms of good moldability.
Further, the transparent resin sheet used in the present invention has fish-eye irregularities at least on the back surface thereof. The back surface is the surface on the side on which the pattern ink layer is formed, and at the same time the back surface is the surface on the injection molded product side when the decorative sheet is laminated on the surface of the injection molded product.
[0016]
By the way, among the irregularities on the back surface of the transparent substrate sheet, the cause of ink omission is not the general irregularities that swell, but the projections that are isolated and projecting larger than the surrounding smooth level surface, that is, fish eyes (Fish-eye unevenness). In general, when printing is performed on the unevenness caused by such fish eyes, the ink does not transfer to the peripheral portion of the unevenness F caused by the fish eyes, resulting in ink loss K, as conceptually shown in FIG. The unevenness F due to fish eyes is caused by raw material unmelted materials, foreign matters, carbides, and the like when the transparent base sheet is manufactured. As for the size of the unevenness F by the fish eye, the size (in the horizontal direction) is about 0.01 to 0.8 mm and the height is about 1 to 20 μm in many cases. Of course, the generation of fish eyes varies depending on the resin and thickness of the transparent base sheet, but in the case of a decorative sheet for simultaneous injection molding, the thickness is often 50 to 150 μm. As a result, the number of fish eyes as described above increases. In general, the most common are fish eyes having a size of 0.03 to 0.05 mm and a height of 5 to 10 μm. The height has a greater influence on the occurrence of ink loss than the size.
[0017]
The ink loss K recognized as a printing defect is also affected by the pattern, etc., but the ink loss that is treated as a defect is usually related to its size and number, for example, an area of 0.5 mm ² More than 0.1m ink loss ² It becomes defective when there are two or more.
[0018]
Table 1 shows the results of investigating the correlation between the size of the fish-eye unevenness and the size (area) of ink loss generated thereby. In Table 1, the area leading to defects 0.5mm ² Paying attention to the above ink loss, it can be seen that the ink loss occurs if the height of the fish-eye irregularities is small but the height is high.
[0019]
[Table 1]

[0020]
The thermoplastic resin used for the transparent base sheet is not particularly limited as long as it satisfies the transparency, moldability and the like required depending on the application. For example, acrylic resins such as polymethyl (meth) acrylate, polybutyl (meth) acrylate, methyl (meth) acrylate-butyl (meth) acrylate copolymer, methyl (meth) acrylate-styrene copolymer, etc. ) Acrylate means acrylate or methacrylate. The same applies below. ], Polyethylene, polypropylene, polymethylpentene, polybutene, ionomer, ethylene-propylene copolymer, ethylene-propylene-butene copolymer, polyolefin resin such as olefin thermoplastic elastomer, polybutylene terephthalate, polyester thermoplastic elastomer , Polyester resins such as completely amorphous polyester, styrene resins such as polystyrene and acrylonitrile-styrene copolymer, vinyl resins such as vinyl chloride resin, vinylidene chloride resin, vinyl acetate-vinyl chloride copolymer, polyvinyl butyral, Fluorine resins such as polyvinyl fluoride, polyvinylidene fluoride, and ethylene-tetrafluoroethylene copolymer, polyamide resins such as nylon 6 and nylon 66, polycarbonate resins, and the like. A single layer or a laminate of two or more layers of these resin sheets (films) is used for the transparent substrate sheet. In addition, the thickness of a transparent base material sheet is about 50-150 micrometers normally.
[0021]
In addition, in the transparent base sheet, a colorant, an anti-friction agent, a lubricant, an antioxidant, a light stabilizer, a plasticizer, and an antistatic agent are appropriately selected as necessary within the range not affecting transparency. Additives such as chemicals, antifungal agents, antibacterial agents, and flame retardants. In addition, as these various additives, well-known additives according to a use can be used.
[0022]
For example, particularly in applications where weather resistance (light) resistance is required, organic light absorbers such as benzotriazole-based, benzophenone-based, and salicylic acid ester-based light stabilizers, and fine particles having a particle size of 0.2 μm or less are used. Addition of radical scavengers such as inorganic ultraviolet absorbers such as zinc oxide, cerium oxide and titanium oxide, hindered amine radical scavengers, piperidine radical scavengers is preferred. The addition amount is usually in the range of 0.1 to 5% by mass in both cases.
[0023]
In addition, when it is necessary to improve the adhesion between the transparent substrate sheet and the transparent smoothing coating film, surface treatment such as corona discharge treatment, plasma treatment, ozone treatment, and known easy adhesion treatment such as primer layer formation are performed. You may give it. A silane coupling agent or the like is used for the primer layer.
[0024]
[Transparent smoothing coating]
The transparent smoothing coating film 2 is a coating film for smoothing the fish-eye irregularities as described above, but is a transparent coating film so that the pattern ink layer formed on the back side of the transparent substrate sheet can be seen through. . In order to make the coating film a transparent coating film and a coating film that can smooth the fish-eye unevenness, the transparent smoothing coating film is preferably formed of a transparent resin.
[0025]
The transparent resin is not particularly limited as long as the transparency is satisfied. For example, one or more of acrylic resin, urethane resin, vinyl chloride-vinyl acetate copolymer, chlorinated polypropylene, polyester resin, and the like can be used. What is necessary is just to select a mixture suitably in consideration of the adhesiveness of these both layers, etc. according to the material of a transparent base material sheet and a pattern ink layer.
[0026]
Examples of the acrylic resin include acrylics such as polymethyl (meth) acrylate, polybutyl (meth) acrylate, methyl (meth) acrylate-butyl (meth) acrylate copolymer, and methyl (meth) acrylate-styrene copolymer. Resin, or methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, octyl (meth) acrylate, cyclohexyl (meth) acrylate, etc., 2-hydroxyethyl (meth) acrylate, 2-hydroxy-3 -An acrylic resin such as an acrylic polyol obtained by copolymerizing a (meth) acrylic acid ester having a hydroxyl group in a molecule such as phenoxypropyl (meth) acrylate is used alone or in combination of two or more.
[0027]
As the urethane resin, a two-component curable urethane resin, a thermoplastic urethane resin, or the like is used. The two-component curable urethane resin has a polyol as a main component and a polyvalent isocyanate as a crosslinking agent. Examples of the polyol include acrylic polyol, polyester polyol, polycarbonate polyol, polyether polyol, and polyurethane polyol. Examples of the polyvalent isocyanate include 2,4-tolylene diisocyanate, xylene diisocyanate, diphenylmethane-4,4'-diisocyanate, and the like. An aliphatic (or alicyclic) isocyanate such as aromatic isocyanate, 1,6-hexamethylene diisocyanate, isophorone diisocyanate, hydrogenated tolylene diisocyanate, or the like is used. Alternatively, as the isocyanate, a multimer or adduct of these isocyanates may be used.
[0028]
The transparent smoothing coating is preferably formed in one step. That is, a single-layer coating film formed in one step is preferable. The reason for this is that if the thickness is increased by thin film coating, the uneven shape of the fish-eye unevenness on the back surface of the transparent base sheet is picked up and stacked, so that ink omission cannot be eliminated. The cross-sectional view of FIG. 4 is a diagram conceptually showing the situation of the coating film 6 having a multi-layer structure and increased thickness by this multi-step coating. As shown in FIG. 4A, the first layer 6a [FIG. 4B] and the second layer 6b [FIG. 4B] are sequentially formed on the back surface of the transparent base sheet 1 having fish-eye irregularities F on the back surface. 4 (C)], the third layer 6c [FIG. 4 (D)], and even if the coating film 6 having a three-layer structure is formed by repeatedly coating the coating film, the unevenness F is eliminated and the film is not flattened. Show.
[0029]
On the other hand, as shown conceptually in the cross-sectional views of FIGS. 5A and 5B, if the coating film is applied with a thick film in one step and the recess is filled only with the first layer 6a, the fish eye By reducing the height of the convex portions of the concavo-convex F, the printed surface can be smoothed and ink loss can be eliminated. Therefore, the first layer 6 a is a coating film suitable for the transparent smoothing coating film 2.
[0030]
The level of smoothing by the transparent smoothing coating film is ideally smooth (flattened) the fish-eye irregularities on the back surface of the transparent base material sheet, but in practice, the transparent base material is transparent. The level difference of the unevenness (on the coated surface) after coating is reduced rather than the level difference of the unevenness on the back side of the sheet, and the degree to which ink loss is not practically hindered (average 1 / decoration of 1 decorative molded product) Area) is sufficient.
[0031]
In addition, as a transparent smoothing coating film, a single-layer coating film by one-step coating is preferable, but as a coating method for forming such a coating film, the difference in height of fish-eye unevenness There is no particular limitation as long as it is a method that can be applied to such a thickness that ink removal can be practically improved. For example, a coating method capable of forming a coating thickness of 2 μm or more by a single coating such as gravure reverse coating, roll coating or comma coating is preferred.
[0032]
[Picture ink layer]
The pattern ink layer 3 is made of a known printing method such as gravure printing, letterpress printing, offset printing, silk screen printing, transfer printing from a transfer sheet, ink jet printing, or ink-jet printing using ink (or coating liquid). It can be formed by a conventionally known forming method. The pattern ink layer is partially formed on the entire surface (all solid layers) or in a desired pattern (pattern pattern layer). In addition, when forming in the whole surface, it can also form using conventionally well-known coating methods, such as a gravure coat and a roll coat.
[0033]
The ink used for forming the pattern ink layer (printing, coating, etc.) is usually composed of a vehicle composed of a binder, a colorant such as a pigment or a dye, and various additives appropriately added thereto. A simple substance or a mixture of acrylic resin, vinyl chloride-vinyl acetate copolymer, chlorinated polypropylene, polyester resin, cellulosic resin, urethane resin or the like is used. In addition, as said acrylic resin and urethane resin, resin as listed with the transparent smoothing coating film mentioned above, for example can be used.
[0034]
Examples of the coloring agent include titanium white, zinc white, petal, vermilion, ultramarine, cobalt blue, titanium yellow, yellow lead, carbon black, iron black, and other inorganic pigments, isoindolinone yellow, benzidine yellow, Known colorants such as organic pigments (or dyes) such as quinacridone red, permanent red 4R, phthalocyanine blue, indanthrene blue RS, and aniline black can be used.
[0035]
In addition, the pattern expressed by the pattern ink layer is, for example, a wood grain pattern, a stone pattern, a grain pattern, a cloth pattern, a tiled pattern, a brickwork pattern, a leather pattern, a geometric pattern, a character, a symbol, a solid surface, etc. However, it is used 1 type or in combination of 2 or more types according to a use.
[0036]
[Adhesive layer]
In order to improve the adhesiveness with the injection-molded product which is the adherend, the back side of the decorative sheet is appropriately treated as required, such as corona discharge treatment, plasma treatment, primer coating, etc. The adhesive layer 4 may be provided after or without the easy adhesion treatment.
By providing the adhesive layer 4, it is easy to improve the adhesion with the injection molded product, and the range of material selection for the injection molded product is widened. As a result, the cost can be easily reduced in terms of the injection molded material.
[0037]
As the adhesive layer 4, a known resin such as a thermoplastic resin or a thermosetting resin is used as a heat-sensitive adhesive, for example, depending on the adherend material. In the thermoplastic resin, for example, vinyl acetate resin, vinyl chloride-vinyl acetate copolymer, acrylic resin, thermoplastic polyester resin, polyamide resin, ionomer, chlorinated polyolefin resin, thermoplastic urethane resin, rubber resin, etc. Alternatively, a mixture of two or more kinds is used. As the thermosetting resin, phenol resin, urethane resin such as blocked isocyanate curing type, epoxy resin, or the like is used.
The adhesive layer is formed by known printing or coating methods such as gravure printing, roll coating, and the like using an adhesive made of these resins. The thickness of the adhesive layer is not particularly limited, but is usually about 1 to 100 μm.
[0038]
Decorative molded products :
The decorative molded product of the present invention is such that the decorative sheet S of the present invention injection-molds the pattern ink layer 3 side with respect to the transparent base sheet 1 as illustrated in the cross-sectional view of FIG. This is a molded product having a structure laminated on the surface of the resin molded product 5 so as to face the product 5 side. That is, the decorative molded product P of the present invention illustrated in the figure has an adhesive layer 4, a pattern ink layer 3, a transparent smoothing coating film 2, and a transparent base sheet 1 on the injection molded product 5 in order. The fish-eye-like irregularities F that are laminated and present on the back surface on the injection molded product 5 side of the transparent base sheet 1 are molded articles that are flattened by the transparent smoothing coating film 2. The adhesive layer 4 may be omitted.
In addition, lamination | stacking of the decorating sheet S on the injection molded product 5 can be suitably performed with the injection molding simultaneous decorating method.
[0039]
[Injection molding]
The resin of the injection molded product 5 is basically not particularly limited and may be a known resin. It may be selected according to the required physical properties and cost of the product. For example, in the case of a thermoplastic resin, a polyolefin resin such as polyethylene, polypropylene, polybutene, polymethylpentene, ethylene-propylene copolymer, ethylene-propylene-butene copolymer, olefin thermoplastic elastomer, or ABS ( Examples thereof include acrylonitrile-butadiene-styrene copolymer) resin, AS (acrylonitrile-styrene copolymer) resin, styrene resin, acrylic resin, vinyl chloride resin, and polycarbonate resin. Further, in the case of a curable resin, it is a two-component curable resin, for example, an uncured resin solution such as a urethane resin, an unsaturated polyester resin, or an epoxy resin. The thermoplastic resin is melted by heating and injected in a fluid state, and the curable resin (its uncured product) is injected at room temperature or appropriately heated and injected in a fluid state.
[0040]
In addition, you may use resin colored by adding a coloring agent suitably according to a use in resin. As the colorant, a known colorant as described in the above-mentioned pattern ink layer may be used. Further, in the resin, various known additives such as silica, alumina, talc, calcium carbonate, aluminum hydroxide and other inorganic powders, fillers such as glass fibers, stabilizers, lubricants, elastomers and the like are appropriately added as necessary. Contain.
[0041]
[Molded product shape]
In addition, the decorative molded product is usually a three-dimensional object in which the decorative sheet has a non-planar surface such as an uneven surface. However, the decorative molded product of the present invention does not exclude a three-dimensional object in which the laminated surface of the application sheet is flat but the other surface is non-planar, and a plate-like object in which the laminated surface is flat.
[0042]
Manufacturing method of decorative molded products :
In addition, in order to obtain the decorative molded product of the present invention, it is obtained by using the decorative sheet of the present invention, and a method for laminating the decorative sheet on the injection molded product at that time is an injection described later. A molding simultaneous decorating method is suitable. However, the method of obtaining the decorative molded product of the present invention is not necessarily limited to this injection molding simultaneous decoration method. Depending on the injection-molded product to be adhered (the shape of the surface to be decorated of the decorative sheet), the production equipment that can be prepared, and the like, other lamination methods may be employed as appropriate. For example, the so-called vacuum forming lamination method described in Japanese Patent Publication No. 56-45768 (overlay method), Japanese Patent Publication No. 60-58014 (vacuum press method), Japanese Patent Publication No. 61-5895, Japanese Patent Publication No. 56-23377. A so-called lapping method described in a gazette or the like may be used. However, of course, it is preferable to laminate by the injection molding simultaneous decorating method from the viewpoint that the molding of the injection molded product and the decorating can be simultaneously performed in one step, and the production efficiency is good.
[0043]
[Injection molding simultaneous decoration method]
Next, among the above, the injection molding simultaneous decorating method will be described in detail. The injection molding simultaneous decorating method is roughly classified into a laminated form and a transfer form, but the method that can be adopted in the present invention is the laminated form. As described in Japanese Patent Publication No. 50-19132, Japanese Patent Publication No. 43-27488, etc., the injection molding simultaneous decorating method of the laminated form is arranged between both male and female molds of injection molding, This is a method in which a resin in a fluid state is injected and filled in a mold, and a decorative sheet is laminated on the surface of the injection molded article at the same time as molding.
[0044]
In the injection molding simultaneous decorating method, even when the decorative sheet is not preheated, the decorative sheet receives heat pressure from the injection resin. Accordingly, the decorative sheet may be preformed either in a form that is performed or not. Moreover, the preheating of the decorative sheet may or may not be performed. In addition, at the time of preforming, the decorative sheet is usually preheated.
[0045]
Needless to say, when the decorative sheet has a large aperture, it is preferable to perform preforming. On the other hand, in the case where the decoration sheet has a small aperture, the decoration sheet may be formed by the resin pressure and the resin heat of the injected resin in a fluid state. At this time, if the squeezing is shallow, the decorative sheet may be formed only by the resin pressure and the resin heat of the resin in a fluid state filled in the mold at the same time as the resin injection without preforming. Even when the decorative sheet is molded with resin pressure and resin heat, the decorative sheet may be heated only using the resin heat of the injection resin and not preheated. In addition, the preforming of the decorative sheet is usually performed by using the injection mold as a vacuum mold, but before supplying the decorative sheet between the molds, a separate vacuum mold is used outside the injection mold. Pre-formation (off-line pre-formation) such as vacuum forming a decorative sheet may be used. However, the pre-molding is preferably performed in the form of using both an injection mold and a vacuum mold because the decorative sheet can be laminated efficiently and accurately. However, when the preformed decorative sheet is manufactured in advance in another place, the preforming is preferably in the form of off-line preforming. In the description of the present invention, vacuum forming includes vacuum / pressure forming.
[0046]
With reference to the conceptual diagram of FIG. 6, the injection molding simultaneous decorating method will be described in one form. The form described here is a form in which the decorative sheet is heated and softened between the molds and pre-molded by vacuum molding with an injection mold before the mold is clamped, and then the mold is clamped and the resin is injected. .
Moreover, this form is a more preferable form when the decoration sheet | seat is deeply drawn in the above-mentioned various combinations of pre-molding and preheating of the decorative sheet.
[0047]
First, as shown in FIG. 6A, the injection mold includes a mold (male mold) Ma having a runner and a gate (gate) communicating with the injection nozzle, and a suction hole 41 on the cavity surface. A pair of molds (female molds) Mb that also serves as a sheet preforming mold is used. These molds are made of metal such as iron or ceramics. In the mold open state, the decorative sheet S is supplied between both molds Ma and Mb, and the decorative sheet S is fixed to the mold Mb by pressing it with a sheet clamp 42 having a frame shape in plan view. At this time, it goes without saying that the pattern ink layer side (with respect to the transparent substrate sheet) is the injection resin side on the right side of the drawing. Next, as shown in FIG. 6B, the heater 43 that has been retracted at the retracted position outside the mold (in the drawing, above the mold) is appropriately moved and inserted between both molds, and the decorative sheet is heated by the heater 43. Soften. The heating is, for example, non-contact radiation heating, but may be conduction heating by contact. Then, vacuuming is performed by suction from the suction hole, and the decorative sheet is preformed along the cavity surface of the mold Mb. Next, the heater 43 is retracted from between both molds to the retracted position outside the mold, both molds are clamped as shown in FIG. 6C, and a resin in a fluid state such as a heat-melted state is placed in the cavity formed by both molds. Fill. 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 decorative sheet, trimming is appropriately performed to obtain a decorative molded product.
[0048]
【Example】
Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples.
[0049]
[Example 1]
A decorative sheet S configured as shown in FIG. 1 was produced as follows. First, a resin sheet having a thickness of 125 μm made of an uncolored transparent acrylic resin was prepared as the transparent base sheet 1. And the transparent coating liquid which consists of a 5 to 5 mass ratio mixture of an acrylic resin and a vinyl chloride-vinyl acetate copolymer on the surface made into the back side of this transparent base material sheet is 3 micrometers in thickness (dry) by the gravure reverse method. And the like, the same applies hereinafter) was applied once to form a transparent smoothing coating film 2. For coating, a plate having a screen line number of 95 L / cm and a plate depth of 95 μm was used.
[0050]
Furthermore, the pattern ink layer 3 was formed on the surface of the transparent smoothing coating film 2 side. The pattern ink layer 3 is a three-layer overlay using a color ink comprising a mixture of an acrylic resin and a vinyl chloride-vinyl acetate copolymer in a 5 to 5 mass ratio as a binder resin and a color pigment added as a colorant. It was formed as a layer with a woodgrain design by a gravure printing method.
[0051]
Further, a coating liquid made of a vinyl chloride-vinyl acetate copolymer is applied to the surface on the pattern ink layer 3 side by a gravure reverse method using a plate having a screen line number of 40 L / cm, and a thickness of 2 μm. The desired adhesive sheet S was obtained by forming the adhesive layer 4.
[0052]
Then, the decorative sheet is laminated on the surface simultaneously with the injection molding by the injection molding simultaneous decorating method by the method as shown in the conceptual diagram of FIG. 6, and as shown in the partial sectional view of FIG. With the configuration, a desired decorative molded product P in which a decorative sheet S was laminated on the surface of the injection molded product 5 was produced.
[0053]
In addition, simultaneous injection molding decoration was performed as follows. First, the winding roll of the continuous belt-like decorative sheet was mounted on the sheet feeding device of the injection molding simultaneous decorating device, and the decorative sheet was fed by one shot between the male and female molds in the mold open state. The decorative sheet was supplied between the male and female molds with the pattern ink layer side facing the male mold side (relative to the transparent substrate sheet). Then, the sheet clamp 42 installed on the female mold was closed, and the decorative sheet supplied between the female mold parting surface and the sheet clamp was fixed to the female mold parting surface. The female parting surface portion corresponding to the sheet clamp is provided with a groove over the entire circumference of the female cavity, and a rubber O-ring is embedded in the groove and pressed by the sheet clamp by the O-ring. It has a structure that prevents air from leaking due to a gap between the decorative sheet and the female parting surface.
[0054]
After that, the panel heater 43 of the infrared radiation heating method that was kept waiting at the retracted position outside the mold was inserted between the male and female molds, and the decorative sheet was heated to 130 ° C. to be softened. Then, vacuuming was performed from the groove-shaped suction hole 41 provided in the female-type cavity surface, heating a decorating sheet with a heater. By this vacuum forming, the decorative sheet was preformed into the shape of the female cavity. Thereafter, the heater was retracted from the inside of the mold to a retracted position outside the mold, and both the male and female molds were clamped.
[0055]
Then, the heat-resistant ABS resin was injected from the male gate, and at the same time as the molding of the injection molded product, the decorative sheet was laminated and integrated on the surface to form a decorative molded product.
The injection molding conditions are as follows: injection resin temperature is 230 ° C., hot runner is manifold temperature is 240 ° C., gate temperature is 235 ° C., die is 35 ° C. for female mold and 45 ° C. for male mold, injection time is 5 s. The cooling time is 20 s. And after mold opening, the decorative molded product was taken out from the mold with an automatic product take-out device. In addition, the area of the decorative surface of the decorative molded product is about 250cm ² It is.
[0056]
[Comparative Example 1]
In Example 1, the decorative sheet was formed in the same manner as in Example 1, except that the formation of the transparent smoothing coating film was omitted when the decorative sheet was produced, and the pattern ink layer was formed directly on the transparent base sheet. And the decorative molded product was produced.
[0057]
[Performance evaluation]
The state of the fish eye (in the state) of the transparent base sheet and the state of occurrence of ink loss of the obtained decorative sheet were evaluated.
Ink loss is an area that causes poor appearance 0.5mm ² 1m above ² In conversion per unit, in Comparative Example 1, 16 pieces / m ² However, in Example 1, 5 / m ² Decreased. Therefore, the dimension (decoration area) of a normal decorative molded product is 0.1 m. ² Since there are many below, the area (normal maximum) equivalent to 0.1 m per molded product ² When evaluated by the number of missing ink per hit, in the configuration without the transparent smoothing coating film as in Comparative Example 1, the area was 0.1 m. ² Probability of entering two of them is quite high, and mass production with stable quality is difficult. However, when the transparent smoothing coating film is provided as in Example 1, the area is 0.1 m. ² Among them, that is, 0.5 to 1 per molded product, and mass production was possible with almost stable quality. As a result, by providing a transparent smoothing coating film, even if the number of steps increased, defective products were reduced, resulting in cost reduction.
[0058]
【The invention's effect】
(1) According to the decorative sheet of the present invention, even if the transparent base sheet used has fish-eye irregularities, it is possible to prevent the occurrence of ink loss. Moreover, since the transparent smoothing coating provided for this purpose is a transparent layer, it does not adversely affect the color tone and visibility of the pattern ink layer. As a result, it is possible to stably prevent the ink loss defect even in the case of a transparent substrate sheet that has been conventionally unable to be adopted due to poor surface smoothness due to fish-eye unevenness. For this reason, the range of transparent base sheet selection is widened, it is easy to reduce costs, and it is also possible to select transparent base sheet with more emphasis on formability, so the range of shapes for decorative molded products is also widened It is done.
(2) Further, if the adhesive layer is also laminated, it is easy to improve the adhesion to the injection molded product, and the range of material selection for the injection molded product is widened. As a result, the cost can be easily reduced in terms of the injection molded material.
(3) Further, according to the decorative molded product of the present invention, the effect of the decorative sheet of the present invention can be obtained, and as a result, occurrence of ink loss due to fish-eye unevenness can be prevented. It can be used even on a transparent base sheet that has been inadequate due to the unevenness of the surface and the lack of ink generated. For this reason, the range of selection of the transparent base material sheet is widened, the cost reduction and the selection with more emphasis on formability are possible, and the width corresponding to the shape of the decorative molded product is also widened.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view illustrating one embodiment of a decorative sheet of the present invention.
FIG. 2 is a cross-sectional view illustrating one embodiment of a decorative molded product of the present invention.
FIGS. 3A and 3B are a cross-sectional view and a plan view conceptually illustrating the occurrence of ink loss due to unevenness on the back surface of the sheet.
FIG. 4 is a conceptual diagram for conceptually explaining defects at the time of overcoating with a transparent smoothing coating film.
FIG. 5 is a conceptual diagram for conceptually explaining how the transparent smoothing coating film is applied once.
FIG. 6 is a conceptual diagram illustrating an example of the simultaneous injection molding decoration method.
[Explanation of symbols]
1 Transparent substrate sheet
2 Transparent smoothing coating
3 Pattern ink layer
4 Adhesive layer
5 Injection molded products
6 Coating film
6a 1st layer (of coating)
6b Second layer (of the coating)
6c 3rd layer (of coating)
41 Suction hole
42 Sheet clamp
43 Heater
F Fish-eye shaped irregularities
K ink missing
Ma injection mold (male mold)
Mb injection mold (female)
P decorative molded product
S decoration sheet

Claims (3)

On the back surface of the transparent substrate sheet having a fish-eye-like irregularities on at least the back surface, successively, the texture smoothing, Ri formed by flattening, and one step of coating a single layer formed by coating formed Ru transparent smooth from A laminate-type decorative sheet for simultaneous injection molding decoration, which is formed by laminating a chemical coating film and a pattern ink layer.   The decorative sheet according to claim 1, further comprising an adhesive layer laminated on the back of the pattern ink layer.   A decorative sheet, wherein the decorative sheet according to claim 1 or 2 is laminated on the surface of an injection-molded product so that the pattern ink layer side faces the injection-molded product side with respect to the transparent base sheet. Molding.

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