JP3845945B2 - Recycling method of resin material with coating film - Google Patents

Description

【０００９】
このようなキノン構造やキノイド構造の化合物は赤色や橙色に着色している場合が多く、このため再生樹脂を用いた製品に黄変が生じる恐れがあった。
また分解工程後に、真空吸引などにより塗膜分解促進剤とともにこのような黄変原因物質を脱揮することも考えられるが、黄変原因物質は比較的高分子量であるために、真空吸引程度では黄変原因物質を充分に脱揮することが困難であり、残留する黄変原因物質により黄変が生じる恐れがある。
【００１０】
本発明はこのような事情に鑑みてなされたものであり、生成した黄変原因物質を速やかに脱揮し、あるいは黄変原因物質を分解して黄変しにくい物質に変化させ、もって再生樹脂の黄変を防止することを目的とする。
【００１１】
【課題を解決するための手段】
上記課題を解決する請求項１に記載の塗膜付き樹脂材の再生処理方法の特徴は、塗膜付き樹脂材を粉砕して樹脂基材と塗膜とからなる細片とする粉砕工程と、細片を溶融状態でアルカリ性の塗膜分解促進剤と接触させ塗膜を分解して分解溶融物とする分解工程と、分解溶融物から塗膜の分解生成物と塗膜分解促進剤とを除去する脱揮工程と、よりなる塗膜付き樹脂材の再生処理方法であって、
分解工程では、細片を溶融状態で塗膜分解促進剤と接触させた後に、塗膜分解促進剤及び黄変原因物質の脱揮を促進する脱揮助剤を塗膜付き樹脂材の１００重量部に対して０．１〜２０重量部の範囲で分解溶融物に添加することにある。
【００１２】
また上記課題を解決する請求項２に記載の塗膜付き樹脂材の再生処理方法の特徴は、塗膜付き樹脂材を粉砕して樹脂基材と塗膜とからなる細片とする粉砕工程と、細片を溶融状態でアルカリ性の塗膜分解促進剤と接触させ塗膜を分解して分解溶融物とする分解工程と、分解溶融物から塗膜の分解生成物と塗膜分解促進剤とを除去する脱揮工程と、よりなる塗膜付き樹脂材の再生処理方法であって、分解溶融物及び脱揮工程後の再生樹脂の少なくとも一方に紫外線を照射することにある。
【００１３】
【発明の実施の形態】
請求項１及び請求項２に記載の発明において、粉砕工程はそれぞれ従来と同様に行うことができる。また細片の大きさは特に制限されないが、処理時間を短縮するためにはできるだけ細かくすることが望ましい。
請求項１及び請求項２に記載の発明において、アルカリ性の塗膜分解促進剤としては、アルカリ水酸化物、アルカリ土類水酸化物などを用いることもできるが、１級アミン又は２級アミンを用いることが望ましい。１級アミン又は２級アミンを用いることにより、アミノリシス反応により塗膜の分解が一層促進される。
【００１４】
このような１級アミンや２級アミンとしては、メチルアミン、エチルアミン、プロピルアミン、イソプロピルアミン、ブチルアミン、イソブチルアミン、sec-ブチルアミン、tert- ブチルアミン、エチレンジアミン、プロピレンジアミン、ブチレンジアミン、ジメチルアミノプロピルアミンなどの１級アミンやジメチルアミン、ジエチルアミンなどの２級アミン、エタノールアミン、プロパノールアミン、ブタノールアミンなどのアルコール性アミンなどの沸点が２５０℃以下のアミンが挙げられ、これらの１種類あるいは２種類以上を組み合わせて用いることができる。なかでも沸点１５０℃以下の１級アミンが効果が大きく、沸点１１６℃のエチレンジアミンは、脱揮もしやすく塗膜分解効果が大であり特に好ましい物質である。
【００１５】
また、前記アミンとともにアルコ−ルや水を添加すれば、塗膜分解促進剤の浸透力が高まったり、混練装置内の圧力が増大したりして、塗膜を一層効率良く分解することができる。アルコ−ルとしては、メタノール、エタノール、プロパノール、iso-プロパノール、ブタノール、iso-ブチルアルコ−ル、sec-ブチルアルコ−ル、tert- ブチルアルコ−ル、エチレングリコール、メチルセロソルブ、エチルセロソルブ、プロピルセロソルブ、ブチルセロソルブ、１−メトキシ−２−プロパノール等の沸点２５０℃以下のアルコ−ルの１種類または２種類以上を組み合わせて用いることができる。なかでも、エチルセロソルブは沸点も１５０℃以下で、塗膜分解に対する効果も大きく、より好ましい。
【００１６】
１級アミンや２級アミンを含む塗膜分解促進剤を使用する場合は、塗膜分解促進剤の添加量の総量が塗膜付き樹脂材１００重量部に対して１．５〜５０重量部であり、かつ、そのうちの１級アミンまたは２級アミンが塗膜付き樹脂材１００重量部に対して１．５〜５０重量部を占めることが望ましい。
塗膜分解促進剤の添加量の総量や１級アミンまたは２級アミンの使用量が上記の範囲より過少であると、塗膜分解促進剤の樹脂中への分散や塗膜分解速度が低下し、一方、過大であると、塗膜分解促進剤の脱揮に手間取り、結局いずれの場合もリサイクルのコストメリットが低下する。
【００１７】
なお、３級アミン又は４級アンモニウム塩を塗膜分解促進剤として用いることもできる。しかしこの場合は、アルコ−ルや水を併用することが必要である。この場合の３級アミンまたは４級アンモニウム塩は求核性触媒であって、分解反応の反応剤であるアルコ−ルや水の水酸基の水素を引き抜き、塗膜との反応性の高いアルコキシドを生成することによって、アルコリシス反応や加水分解による塗膜の分解を促進する。
【００１８】
このような３級アミンまたは４級アンモニウム塩としては、トリメチルアミン、トリエチルアミン、トリプロピルアミン、Ｎ，Ｎ，Ｎ’，Ｎ’- テトラメチルエチレンジアミン、Ｎ，Ｎ，Ｎ’，Ｎ’- テトラメチルプロピルジアミン、Ｎ，Ｎ，Ｎ’，Ｎ’- テトラメチルヘキサメチレンジアミン、Ｎ，Ｎ，Ｎ’，Ｎ’，Ｎ”- ペンタメチルジエチレントリアミン、Ｎ- メチルモルホリン、Ｎ- エチルモルホリン、トリエチレンジアミン、Ｎ，Ｎ- ジメチルベンジルアミン、ジメチルエタノールアミン、ジメチルアミノプロピルアミン、Ｎ，Ｎ，Ｎ’，Ｎ’- テトラメチルジエチレントリアミンなどの３級アミンや、水酸化テトラメチルアンモニウム、水酸化テトラエチルアンモニウム、水酸化テトラプロピルアンモニウムなどの４級アンモニウム塩等で、沸点あるいは自己分解温度が２５０℃以下のものを１種類あるいは２種類以上を組み合わせて用いることができる。
【００１９】
３級アミンや４級アンモニウム塩と併用するアルコ−ルは、１級アミンまたは２級アミンと併用するアルコ−ルとして前記したものと同じである。
３級アミンあるいは４級アンモニウム塩をアルコ−ルや水と併用する場合は、３級アミンあるいは４級アンモニウム塩が塗膜付き樹脂材１００重量部に対して１．５〜１０重量部を占めることが望ましい。
【００２０】
３級アミンあるいは４級アンモニウム塩の使用量が上記の範囲より過少であると触媒としての効果が不十分になり、上記の範囲より過大であっても余り意味がない。
本発明の再生処理方法が適用できる塗膜付き樹脂材の塗膜としては、アルキッドメラミン系、アクリルメラミン系、ウレタン系などの熱硬化性樹脂塗膜が挙げられる。なお、塗膜とともに補修用に用いられるパテ材としてのエステル、ウレタンおよびエポキシ系などの熱硬化性樹脂も効率よく分解することができる。
【００２１】
また本発明の再生処理方法が適用できる塗膜付き樹脂材の樹脂基材としては、例えばポリプロピレン、エラストマー変性ポリプロピレン、ポリエチレン、ＡＢＳ樹脂、ＡＳ樹脂、ポリアミド樹脂、ポリアセタール樹脂などが挙げられる。なお、塗膜あるいは樹脂基材に通常配合されている充填材、顔料、ガラス繊維、その他の添加物は、特に問題にはならない。
【００２２】
請求項１及び請求項２の発明における分解工程では、塗膜付き樹脂材の細片と塗膜分解促進剤とが接触される。この分解工程は加熱して行い、樹脂基材の溶融による熱運動の促進により塗膜の分解が促進される。
溶融した塗膜付き樹脂材中に塗膜分解促進剤を効率的に分散させるためには、樹脂基材の溶融温度以上で、かつ塗膜分解促進剤の沸点以上の高温に加熱し、さらに押出し機などの混練装置を用いて混練しながら行うのが好ましい。混練装置により塗膜には剪断応力が作用するため、塗膜は機械的に破砕され塗膜分解促進剤の作用が促進される。
【００２３】
溶融した塗膜付き樹脂材と塗膜分解促進剤の接触時間は、塗膜の種類、塗膜分解促進剤の種類および量、加熱温度により大きく影響される。一軸あるいは二軸の押し出し装置を混練装置として使用する場合は、通常１．５〜５分程度で、塗膜が１００μｍ以下の大きさに分解できるように、塗膜分解促進剤の種類及び温度を選択する。なお混練装置内では、塗膜分解促進剤に高圧を作用させ、塗膜分解促進剤が液状を維持できるようにするのが効率的である。
【００２４】
脱揮工程は、塗膜の分解生成物および残存する塗膜分解促進剤を分解溶融物から取り除く工程である。この脱揮工程は、分解溶融物を塗膜の分解生成物および塗膜分解促進剤の沸点以上に加熱し、塗膜の分解生成物および残存する塗膜分解促進剤を蒸発させて分離する。この際に真空装置で減圧とし、蒸発による離脱を促進することも好ましい。なお、蒸発した塗膜の分解生成物および塗膜分解促進剤を集めて冷却して凝集することにより回収でき、再び塗膜分解促進剤として使用することもできる。
【００２５】
脱揮工程後の分解溶融物は、例えば押出し機のノズルより取り出される。例えば棒状に押出し、その後ペレット状に切断して、再生樹脂とすることができる。また、直接シート等の所定断面をもつ二次製品に押出すことも出来る。
なお、塗膜付き樹脂材の細片に顔料その他のフィラー、添加剤などを配合し、用途に合わせた色、物性をもつ再生樹脂とすることもできる。例えば顔料を配合することにより再生樹脂を調色することができ、処理後の色付け工程がなくなり処理コストが低減できる。
【００２６】
請求項１の発明の最大の特徴は、塗膜分解促進剤の脱揮を促進する脱揮助剤を分解溶融物に添加することにある。脱揮助剤により、塗膜分解促進剤、塗膜分解物及び黄変原因物質の分圧が低下するため、脱揮工程において脱揮が促進され、分解溶融物から黄変原因物質を容易に除去することができる。この意味において、脱揮助剤はできるだけ沸点が低いものを用いることが好ましく、特に塗膜分解促進剤の沸点より低い沸点をもつものを用いることが望ましい。例えば沸点が１００℃の水、沸点が１５０℃以下のアルコール、あるいは酢酸エチル、蟻酸エチル、蟻酸メチルなどのエステル類なども用いることができる。
【００２７】
この脱揮助剤の添加量は、塗膜付き樹脂材１００重量部に対して０．１〜２０重量部の範囲が好ましい。この範囲より少ないと添加した効果が得られず、この範囲より多く添加すると分解溶融物が冷却されてしまい、安定的に連続運転することが困難となる。
脱揮助剤は酸性とすることも好ましい。酸性の脱揮助剤を添加することにより、上記した脱揮促進作用に加えて黄変原因物質が分解して低分子物質になりやすく、分圧のさらなる低下により脱揮を一層促進することができる。また分解した黄変原因物質は無色物質となるため、再生樹脂中に残留しても黄変が防止される。さらにアルカリ性の塗膜分解促進剤を中和する作用もあり、再生材中に残留した酸化防止剤が塗膜分解促進剤により再び黄変物質に変化するのを防止する効果も得られる。
【００２８】
酸性の脱揮助剤としては、水やアルコールなどの脱揮助剤に酸を添加したものが例示される。この酸としては塩酸、硫酸、蟻酸、酢酸などが例示される。なお、酸度が強すぎると樹脂基材が劣化する恐れがあるので、脱揮助剤は中性から弱酸性の範囲とすることが望ましい。
請求項２の発明の最大の特徴は、分解溶融物及び脱揮工程後の再生樹脂の少なくとも一方に紫外線を照射することにある。紫外線の照射により、キノン構造やキノイド構造が有する共有構造が破壊されるため、再生樹脂の黄変が防止される。
【００２９】
照射される紫外線の光強度は、２５〜２０００μＷ／ｃｍ² の範囲が望ましい。光強度が２５μＷ／ｃｍ² より低いと効果が得られなかったり処理時間が長大となり、２０００μＷ／ｃｍ² より大きくなっても効果が飽和するとともに樹脂基材の分解が生じる場合もある。このような紫外線を発生する光源としては、２００〜５０００Ｗの紫外線ランプ、７０〜５０００Ｗのキセノンランプ、５０〜５０００Ｗのキセノンフラッシュランプ、１００Ｗ以下の低圧水銀ランプ、１５０〜４００Ｗのメタルハライドランプなどが例示される。
【００３０】
紫外線照射を行う時期は、分解工程及び脱揮工程の途中あるいは直後における混練物の溶融状態に行うのが望ましいが、脱揮工程後の固形状態、あるいはペレット化した後などに行ってもよい。
なお、請求項１の発明と請求項２の発明は、それぞれ行ってもよいし両方を行うこともできる。両方を行えば、両方の作用がそれぞれ奏されるため、再生樹脂の黄変を一層確実に防止することができる。
【００３１】
【実施例】
以下、実施例により本発明を具体的に説明する。
本実施例の再生処理方法で使用する装置の概略説明図を図１に示す。
この装置は押出し機１と、冷却槽２と、切断機３と、乾燥機４とから構成されている。押出し機１は、スクリュウがＬ／Ｄ＝５４の２軸混練押出し機であり、４０メッシュのスクリーンメッシュの第１シ−ルリング１０と、３００メッシュのスクリーンメッシュの第２シ−ルリング１１により溶融域１２、化学分解域１３、混練域１４の三つの領域に分けられている。
【００３２】
溶融域１２の前端にはホッパー１５が設けられている。また化学分解域１３の上流側には塗膜分解促進剤を注入する第１注入口１６が設けられ、化学分解域１３の下流側には脱揮助剤を注入する第２注入口１７が設けられている。さらに混練域１４には、揮発性物質を除去するための脱揮口１８が設けられている。脱揮口１８には、二つの冷却器５を介して真空ポンプ５０が連結されている。
【００３３】
この押出し機１では、シリンダ内圧力が１０〜１００（ｋｇ／ｃｍ² ）とされ、混練物の温度が２４０〜２７０℃となるように調整されて、ポリプロピレンの熱劣化を伴わずに塗膜を化学分解することができるようになっている。また処理量は８０〜１２０（ｋｇ／ｈ）とした。
（参考例１）
上記押出し機を用い、以下のようにして本参考例の再生処理方法を行った。
【００３４】
＜粉砕工程＞
先ず、塗膜付き樹脂材として使用済みの補修ウレタン系塗膜付きポリプロピレン製自動車バンパを用意し、図示しない粉砕機を用いて一辺が５〜１０ｍｍ程度の細片に粉砕した。このバンパの樹脂基材中には、酸化防止剤としてのＢＨＴが約０．１重量％含まれている。
【００３５】
＜分解工程＞
次にホッパー１５より上記細片を定量供給し、スクリュウを駆動した。細片は溶融域１２における加温と、剪断摩擦による加熱とで樹脂基材が溶融し、溶融混練されつつ搬送され、第１シ−ルリング１０を通過して次の化学分解域１３に送り出される。
【００３６】
化学分解域１３に移行した溶融混練物に対し、ポンプ６０を駆動して塗膜分解促進剤であるエチレンジアミンを第１注入口１６から注入した。エチレンジアミンの注入量は、細片１００重量部に対して５〜７重量部である。化学分解域１３内では、細片の溶融物とエチレンジアミンとが混練され、スクリュウの剪断力とエチレンジアミンにより塗膜が機械的、化学的に高速分解され低分子化される。
【００３７】
この化学分解域１３では、溶融混練物はエチレンジアミンの沸点（１１５℃）以上の温度となるが、高圧となっているためエチレンジアミンは液状となり易く、溶融混練物中に均一に分散されて塗膜を効率よく分解し分解溶融物となる。
分解された塗膜の塗膜分解物、エチレンジアミン、酸化防止剤などは、それぞれ比較的低分子であるため気化しやすく、押出し機内の分解溶融物は液体・固体・気体が入り混じった状態となっている。
【００３８】
次に化学分解域１３の下流域では、ポンプ６１が駆動され、第２注入口１７から水を注入する。水の注入量は、細片１００重量部に対して０．０４重量部となるようにした。分解溶融物の温度は水の沸点（１００℃）より高いため、水が添加された分解溶融物ではさらに気体種が増えることとなり気体成分の分圧が低下する。
【００３９】
＜脱揮工程＞
次いで分解溶融物が第２シ−ルリング１１を通過すると、真空ポンプ５０の駆動により押出し機１内の圧力が低下し、比較的低分子量物質が気化する。それに加えて水も添加されているため、水を加えない場合に比べて気体成分の種類が増加し、分圧が低下する。したがって系は全圧と分圧の圧力勾配を解消する方向に向かい、つまり気体成分が混練物から出る方向に向かうため、分解溶融物中に含まれる気体成分は脱揮口１８から効率よく排気される。排気成分は、直列に配置された二つの冷却器５により分別捕捉される。なお、脱揮口１８の位置における分解溶融物の温度は２００℃である。
【００４０】
＜ペレット化工程＞
混練域１４では、脱揮された再生樹脂がさらに混練される。そしてノズルを経てストランド状に押出され、冷却槽２で冷却された後、切断機３で切断されてペレット化され、乾燥機４で乾燥されて再生樹脂ペレットとされた。
＜試験＞
得られた再生樹脂ペレットを用いて所定形状の試験片を成形し、従来のバンパ塗装工程に準じて塗装を行った。塗色は、黄変性を評価しやすくするため白色とした。そして塗膜の耐熱性、付着性及び屋外耐候性を試験し、結果を５段階評価で表１に示す。なお、表１には新品のバンパの試験結果も併記してある。
【００４１】
耐熱性は、塗膜が形成された試験片を８０℃で２４０時間加熱し、加熱前後の測色値よりΔｂ値を算出して、２≦Δｂの範囲をランク１、１．５≦Δｂ＜２の範囲をランク２、１≦Δｂ＜１．５の範囲をランク３、０．７≦Δｂ＜１の範囲をランク４、０．７＞Δｂの範囲をランク５とした。もちろんランク数が大きいほど変色度が小さく耐熱性に優れていることを示す。
【００４２】
また付着性はＪＩＳ−Ｋ５４００に準じた碁盤目付着試験で評価し、屋外耐候性は屋外にて７３０日間暴露し暴露前後の色差を測定して評価した。
（実施例１）
第２注入口１７から添加する水の量を、細片１００重量部に対して２．５重量部としたこと以外は参考例１と同様にして再生処理を行った。そして得られた再生樹脂ペレットについて参考例１と同様に試験を行い、結果を表１に示す。
【００４３】
（実施例２）
第２注入口１７から添加する水の量を、細片１００重量部に対して８．５重量部としたこと以外は参考例１と同様にして再生処理を行った。そして得られた再生樹脂ペレットについて参考例１と同様に試験を行い、結果を表１に示す。
（実施例３）
水に代えて、第２注入口１７から濃度０．１Ｎの塩酸水溶液を細片１００重量部に対して２．５重量部注入したこと以外は参考例１と同様にして再生処理を行った。そして得られた再生樹脂ペレットについて参考例１と同様に試験を行い、結果を表１に示す。
【００４４】
（比較例１）
第２注入口１７から水を添加しなかったこと以外は参考例１と同様にして再生処理を行った。そして得られた再生樹脂ペレットについて参考例１と同様に試験を行い、結果を表１に示す。
【００４５】
【表１】

表１より、比較例１では耐熱性が低く実用には不適であるが、参考例１では耐熱性の評価は３で実用レベルにあり、実施例のように水の添加量が多くなるにつれて耐熱性が向上していることがわかる。すなわち水の添加により耐黄変性が向上し、黄変原因物質が非黄変性物質に変化したか、分解溶融物から黄変原因物質が効率よく除去されたかのいずれかにより、再生樹脂ペレット中の黄変原因物質量が低減されていることが明らかである。
【００４６】
また実施例１，２と実施例３との比較により、塩酸を添加することによって再生樹脂ペレット中の黄変原因物質量がさらに低減されていることも明らかである。
（実施例４）
図２に本実施例で用いた装置の概略構成図を示す。この装置は、切断機３と乾燥機４の間に振動ふるい７を設けていること、及び乾燥機４の構成が異なること以外は参考例１で用いた装置と同様の構成である。
【００４７】
振動ふるい７は、図３及び図４に示すように、基台７０と、基台７０にバネ７１を介して保持された振動容器７２とよりなり、振動容器７２の蓋７３の内面に紫外線ランプ８が列設されている。この振動ふるい７では、再生樹脂ペレットは投入口７４から振動容器７２内に投入され、基台７０に設けられたモータ７５の駆動により振動する振動容器７２内で振動しながら出口７６へ運ばれ、出口７６から乾燥機４へ圧送される。そして再生樹脂ペレットは、振動容器７２内を移動する間中、紫外線ランプ８から紫外線を照射されるように構成されている。
【００４８】
また乾燥機４は、図５に示すように外筒４０及び内筒４１と、熱風供給パイプ４２及び攪拌機４３から構成され、外筒４０と内筒４１の間に紫外線ランプ８が高さ方向に列設されている。内筒４１は紫外線透過性の高い樹脂又はガラスから形成されている。また熱風供給パイプ４２からは内筒４１内に１２０〜１５０℃の熱風が供給される。この乾燥機４では、再生樹脂ペレットは攪拌機４３により攪拌されながら熱風により乾燥され、その間中紫外線ランプ８から紫外線が照射される。
【００４９】
上記装置を用い、第２注入口１７からの水の供給を停止したこと以外は参考例１と同様にして混練を行い、冷却槽２及び切断機３を通してペレット化した後、上記振動ふるい７及び乾燥機４を用いて乾燥するとともに紫外線を照射した。紫外線照射時間は延べ５時間であり、照射された紫外線強度は４００μＷ／ｃｍ² である。
【００５０】
得られた再生樹脂ペレットを用い、参考例１と同様に試験した結果を表２に示す。
（実施例５）
第２注入口１７から、細片１００重量部に対して２．５重量部の量の水を供給したこと以外は実施例４と同様にして再生処理を行った。そして得られた再生樹脂ペレットを用い、参考例１と同様に試験した結果を表２に示す。
【００５１】
【表２】

実施例４と比較例１との比較より、紫外線照射により耐熱性が格段に向上していることがわかり、紫外線照射により再生樹脂中の黄変原因物質量が低減されることが明らかである。また実施例４より実施例５の方が耐熱性に優れていることから、水の添加と紫外線の照射とを併用することが望ましいこともわかる。
【００５２】
【発明の効果】
すなわち本発明の再生処理方法によれば、再生された再生樹脂には黄変原因物質の残留がきわめて少なくなる。したがって再生樹脂を用いて形成された再生品の変色が防止され、再生樹脂の用途が拡大される。
【図面の簡単な説明】
【図１】本発明の参考例で用いた装置の模式図である。
【図２】本発明の第４〜５の実施例で用いた装置の模式図である。
【図３】本発明の第４〜５の実施例で用いた装置の振動ふるいの正面図である。
【図４】本発明の第４〜５の実施例で用いた振動ふるいの蓋の背面図である。
【図５】本発明の第４〜５の実施例で用いた装置の乾燥機の断面図である。
【符号の説明】
１：押出し機 ２：冷却槽 ３：切断機
４：乾燥機 ７：振動ふるい １３：化学分解域
１６：第１注入口 １７：第２注入口 １８：脱揮口[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a regeneration processing method for decomposing a coating film from a resin material with a coating film so that it can be used as a recycled resin, and more particularly to a regeneration processing method in which a yellowing cause substance is not included in the recycled resin. .
[0002]
[Prior art]
In recent years, from the viewpoint of effective use of resources and conservation of the global environment, the need to recycle and reuse waste plastics has increased, and PET bottles and polystyrene products have been recycled. Also in the automobile industry, the types of materials are specified for various plastic parts, and considerations are given to facilitate recycling.
[0003]
However, in resin products such as automobile bumpers, a thermosetting resin coating film is often formed on the surface. Therefore, simply melting and kneading such a thin piece of resin material with a coating film causes the coating film piece to be mixed into the recycled resin, resulting in problems such as deterioration in the physical properties of the recycled resin and the appearance quality of the recycled product. In many cases, recycling is difficult.
[0004]
Therefore, a method has been proposed in which a coating film is decomposed from a resin material with a coating film such as a waste bumper into a harmless substance.
For example, Japanese Patent Laid-Open No. 5-200749 discloses Lewis acid such as tin chloride, alkali hydroxide, alkaline earth hydroxide, amine, alcoholate as a method for regenerating a polypropylene composite with a thermosetting resin coating. , A coating film decomposition accelerator composed of one or more of phosphoric acid metal salt, diethanolamine, etc. is added in an amount of 0.01 to 1% by weight to the polypropylene composite, and the coating is thermally decomposed at 200 ° C. or higher. A method is disclosed.
[0005]
In this conventional method for regenerating a resin material with a coating film, the resin material with a coating film is first pulverized into fine pieces, which are put into a twin screw extruder or the like and melt kneaded together with a coating film decomposition accelerator. Thereby, the thermosetting resin coating film is refined by thermal decomposition and uniformly dispersed in the molten resin. Thereafter, the decomposed melt is pelletized and recovered as a recycled resin. Therefore, since the decomposed coating film is uniformly dispersed in the recycled resin as a very fine decomposed product, it is rendered harmless with almost no influence on the physical properties and the appearance of the recycled product.
[0006]
[Problems to be solved by the invention]
By the way, the resin base material constituting the bumper contains various additives such as an antioxidant and an ultraviolet absorber. Various amounts of additives are also contained in the coating film in a small amount. Many of these additives are phenol-based and benzoate-based, and may be dimerized to a quinone structure or a quinoid structure by heat during regeneration treatment or reaction with a coating film decomposition accelerator.
[0007]
For example, BHT (Butylated hydroxy toluen), which is widely used as an antioxidant, is dimerized into a compound having a stilbene quinone or quinoid structure as shown in Chemical Formula 1.
[0008]
[Chemical 1]

[0009]
Such compounds having a quinone structure or a quinoid structure are often colored red or orange, which may cause yellowing in a product using a recycled resin.
In addition, after the decomposition process, it may be possible to devolatilize such a yellowing cause substance together with the coating film decomposition accelerator by vacuum suction or the like. However, since the yellowing cause substance has a relatively high molecular weight, It is difficult to sufficiently volatilize the yellowing cause substance, and yellowing may occur due to the remaining yellowing cause substance.
[0010]
The present invention has been made in view of such circumstances, and the produced yellowing-causing substance is quickly devolatilized, or the yellowing-causing substance is decomposed and changed to a substance that does not easily yellow, thereby having a recycled resin. The purpose is to prevent yellowing.
[0011]
[Means for Solving the Problems]
The feature of the regeneration treatment method for a resin material with a coating film according to claim 1 for solving the above-mentioned problem is a pulverization step for crushing the resin material with a coating film to form a fine piece comprising a resin base material and a coating film, Decomposition process that decomposes the coating film into a decomposed melt by contacting the strips with an alkaline coating decomposition accelerator in the molten state, and removes the decomposition products of the coating film and the coating film decomposition accelerator from the decomposed melt. A devolatilizing step, and a method of regenerating a resin material with a coating film,
In the decomposition process, after contacting the strip with the coating film decomposition accelerator in the molten state, Coating film degradation accelerator And yellowing cause substances A devolatilizing aid that promotes devolatilization In the range of 0.1 to 20 parts by weight with respect to 100 parts by weight of the resin material with a coating film It is to be added to the cracked melt.
[0012]
Moreover, the characteristic of the regeneration processing method of the resin material with a coating film of Claim 2 which solves the said subject is the grinding | pulverization process which grind | pulverizes the resin material with a coating film, and makes it the strip which consists of a resin base material and a coating film, A decomposition step in which the strip is brought into contact with an alkaline coating film decomposition accelerator in a molten state to decompose the coating film to form a decomposition melt, and a decomposition product of the coating film and a coating film decomposition accelerator from the decomposition melt. A devolatilization step to be removed and a method for reclaiming a resin material with a coating film, comprising irradiating at least one of a decomposition melt and a regenerated resin after the devolatilization step with ultraviolet rays.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
In the first and second aspects of the invention, the pulverization step can be performed in the same manner as in the prior art. The size of the strip is not particularly limited, but it is desirable to make it as fine as possible in order to shorten the processing time.
In the inventions according to claim 1 and claim 2, as the alkaline coating film decomposition accelerator, an alkali hydroxide, an alkaline earth hydroxide or the like can be used, but a primary amine or a secondary amine is used. It is desirable to use it. By using the primary amine or the secondary amine, the decomposition of the coating film is further promoted by the aminolysis reaction.
[0014]
Examples of such primary and secondary amines include methylamine, ethylamine, propylamine, isopropylamine, butylamine, isobutylamine, sec-butylamine, tert-butylamine, ethylenediamine, propylenediamine, butylenediamine, dimethylaminopropylamine, etc. Primary amines, secondary amines such as dimethylamine and diethylamine, alcoholic amines such as ethanolamine, propanolamine, and butanolamine, and the like. They can be used in combination. Among these, primary amines having a boiling point of 150 ° C. or lower are particularly effective, and ethylene diamine having a boiling point of 116 ° C. is a particularly preferable substance because it is easy to devolatilize and has a large coating film decomposition effect.
[0015]
Moreover, if alcohol or water is added together with the amine, the penetration of the coating film decomposition accelerator is increased or the pressure in the kneading apparatus is increased, so that the coating film can be decomposed more efficiently. . Examples of the alcohol include methanol, ethanol, propanol, iso-propanol, butanol, iso-butyl alcohol, sec-butyl alcohol, tert-butyl alcohol, ethylene glycol, methyl cellosolve, ethyl cellosolve, propyl cellosolve, butyl cellosolve, One kind or two or more kinds of alcohols having a boiling point of 250 ° C. or lower such as 1-methoxy-2-propanol can be used in combination. Among these, ethyl cellosolve is more preferable because it has a boiling point of 150 ° C. or less and has a large effect on coating film decomposition.
[0016]
When using a coating film decomposition accelerator containing a primary amine or a secondary amine, the total amount of the coating film decomposition accelerator is 1.5 to 50 parts by weight with respect to 100 parts by weight of the resin material with a film. In addition, it is desirable that the primary amine or the secondary amine occupy 1.5 to 50 parts by weight with respect to 100 parts by weight of the resin material with a coating film.
If the total amount of coating film decomposition accelerator added or the amount of primary amine or secondary amine used is less than the above range, the dispersion of the coating film decomposition accelerator in the resin and the coating film decomposition rate will decrease. On the other hand, if it is excessive, it takes time to devolatilize the coating film decomposition accelerator, and in any case, the cost merit of recycling decreases.
[0017]
A tertiary amine or a quaternary ammonium salt can also be used as a coating film decomposition accelerator. However, in this case, it is necessary to use alcohol or water together. The tertiary amine or quaternary ammonium salt in this case is a nucleophilic catalyst, and draws out the hydrogen of the alcohol or water hydroxyl group that is a reaction agent for the decomposition reaction to produce an alkoxide highly reactive with the coating film. By doing so, the decomposition of the coating film by the alcoholysis reaction or hydrolysis is promoted.
[0018]
Such tertiary amines or quaternary ammonium salts include trimethylamine, triethylamine, tripropylamine, N, N, N ′, N′-tetramethylethylenediamine, N, N, N ′, N′-tetramethylpropyldiamine. N, N, N ′, N′-tetramethylhexamethylenediamine, N, N, N ′, N ′, N ″ -pentamethyldiethylenetriamine, N-methylmorpholine, N-ethylmorpholine, triethylenediamine, N, N -Tertiary amines such as dimethylbenzylamine, dimethylethanolamine, dimethylaminopropylamine, N, N, N ', N'-tetramethyldiethylenetriamine, tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide With quaternary ammonium salts such as There is a self-decomposition temperature may be used in combination of one kind or two or more ones of 250 ° C. or less.
[0019]
The alcohol used in combination with the tertiary amine or quaternary ammonium salt is the same as that described above as the alcohol used in combination with the primary amine or the secondary amine.
When a tertiary amine or quaternary ammonium salt is used in combination with alcohol or water, the tertiary amine or quaternary ammonium salt occupies 1.5 to 10 parts by weight with respect to 100 parts by weight of the resin material with a coating film. Is desirable.
[0020]
If the amount of tertiary amine or quaternary ammonium salt used is less than the above range, the effect as a catalyst becomes insufficient, and even if it exceeds the above range, there is not much meaning.
Examples of the coating film of the resin material with a coating film to which the regeneration treatment method of the present invention can be applied include alkyd melamine-based, acrylic melamine-based, urethane-based thermosetting resin coating films. In addition, thermosetting resins such as esters, urethanes, and epoxy resins as putty materials used for repairing together with the coating film can be efficiently decomposed.
[0021]
Examples of the resin base material of the resin material with a coating film to which the regeneration treatment method of the present invention can be applied include polypropylene, elastomer-modified polypropylene, polyethylene, ABS resin, AS resin, polyamide resin, and polyacetal resin. In addition, fillers, pigments, glass fibers, and other additives that are usually blended in the coating film or resin base material are not particularly problematic.
[0022]
In the decomposition step according to the first and second aspects of the present invention, the strip of the resin material with a coating film is brought into contact with the coating film decomposition accelerator. This decomposition process is performed by heating, and the decomposition of the coating film is promoted by the promotion of thermal motion by melting the resin base material.
In order to efficiently disperse the coating film decomposition accelerator in the molten resin material with a coating film, it is heated to a temperature higher than the melting temperature of the resin substrate and higher than the boiling point of the coating film decomposition accelerator, and further extruded. It is preferable to carry out while kneading using a kneading apparatus such as a machine. Since the shear stress acts on the coating film by the kneading apparatus, the coating film is mechanically crushed and the action of the coating film decomposition accelerator is promoted.
[0023]
The contact time between the melted resin material with a coating film and the coating film decomposition accelerator is greatly influenced by the type of coating film, the type and amount of the coating film decomposition accelerator, and the heating temperature. When a uniaxial or biaxial extrusion device is used as a kneading device, the type and temperature of the coating film decomposition accelerator are set so that the coating film can be decomposed to a size of 100 μm or less in about 1.5 to 5 minutes. select. In the kneading apparatus, it is efficient to apply a high pressure to the coating film decomposition accelerator so that the coating film decomposition accelerator can maintain a liquid state.
[0024]
The devolatilization step is a step of removing the decomposition product of the coating film and the remaining coating film decomposition accelerator from the decomposition melt. In this devolatilization step, the decomposition melt is heated to the boiling point of the decomposition product of the coating film and the coating film decomposition accelerator to evaporate and separate the decomposition product of the coating film and the remaining coating film decomposition accelerator. At this time, it is also preferable to reduce the pressure by a vacuum apparatus and promote separation by evaporation. In addition, it can collect | recover by collecting the decomposition products and coating-film decomposition accelerator of the evaporated coating film, and cooling and agglomerating, and can also use it again as a coating-film decomposition accelerator.
[0025]
The decomposition melt after the devolatilization step is taken out from, for example, a nozzle of an extruder. For example, it can be extruded into a rod shape and then cut into a pellet shape to obtain a recycled resin. It can also be directly extruded into a secondary product having a predetermined cross section such as a sheet.
It should be noted that pigments and other fillers, additives, and the like can be blended with the resin material with a coating film to obtain a recycled resin having colors and physical properties suitable for the intended use. For example, by blending a pigment, the recycled resin can be toned, and the coloring process after processing is eliminated, thereby reducing processing costs.
[0026]
The greatest feature of the invention of claim 1 resides in that a devolatilization aid for promoting the devolatilization of the coating film decomposition accelerator is added to the decomposition melt. The devolatilization aid reduces the partial pressure of the coating degradation accelerator, coating degradation product, and yellowing cause substance, so devolatilization is promoted in the devolatilization process, and the yellowing cause substance is easily removed from the decomposition melt. Can be removed. In this sense, it is preferable to use a devolatilization aid having a boiling point as low as possible, and it is particularly desirable to use a devolatilization aid having a boiling point lower than that of the coating film decomposition accelerator. For example, water having a boiling point of 100 ° C., alcohol having a boiling point of 150 ° C. or less, or esters such as ethyl acetate, ethyl formate, and methyl formate can be used.
[0027]
The addition amount of the devolatilization aid is preferably in the range of 0.1 to 20 parts by weight with respect to 100 parts by weight of the resin material with a coating film. If the amount is less than this range, the added effect cannot be obtained. If the amount is more than this range, the decomposed melt is cooled, making it difficult to stably operate continuously.
It is also preferable that the devolatilization aid is acidic. By adding an acidic devolatilization aid, in addition to the devolatilization promoting action described above, the yellowing cause substance is likely to decompose and become a low-molecular substance, and devolatilization can be further promoted by further lowering the partial pressure. it can. Further, since the decomposed yellowing cause substance is a colorless substance, yellowing is prevented even if it remains in the recycled resin. Furthermore, it has the effect | action which neutralizes an alkaline coating-film decomposition accelerator, and the effect which prevents the antioxidant remaining in the recycled material from changing into a yellowing substance again by a coating-film decomposition accelerator is also acquired.
[0028]
Examples of the acidic devolatilization aid include those obtained by adding an acid to a devolatilization aid such as water or alcohol. Examples of the acid include hydrochloric acid, sulfuric acid, formic acid, acetic acid and the like. In addition, since there exists a possibility that a resin base material may deteriorate when acidity is too strong, it is desirable to make a devolatilization assistant into the range of neutrality to weak acidity.
The greatest feature of the invention of claim 2 resides in that at least one of the decomposition melt and the recycled resin after the devolatilization step is irradiated with ultraviolet rays. Irradiation with ultraviolet rays destroys the shared structure of the quinone structure and quinoid structure, thereby preventing yellowing of the recycled resin.
[0029]
The intensity of the irradiated ultraviolet light is 25 to 2000 μW / cm. ² A range of is desirable. Light intensity is 25μW / cm ² If it is lower, the effect cannot be obtained or the processing time becomes long, and 2000 μW / cm ² Even if it becomes larger, the effect is saturated and the resin base material may be decomposed. Examples of such a light source that generates ultraviolet light include a 200 to 5000 W ultraviolet lamp, a 70 to 5000 W xenon lamp, a 50 to 5000 W xenon flash lamp, a low pressure mercury lamp of 100 W or less, and a 150 to 400 W metal halide lamp. The
[0030]
Although it is desirable to perform the ultraviolet irradiation in the molten state of the kneaded product during or immediately after the decomposition step and the devolatilization step, it may be performed in a solid state after the devolatilization step or after being pelletized.
In addition, the invention of claim 1 and the invention of claim 2 may be performed respectively or both. If both are performed, both actions are exhibited, and thus the yellowing of the recycled resin can be more reliably prevented.
[0031]
【Example】
Hereinafter, the present invention will be described specifically by way of examples.
A schematic explanatory diagram of an apparatus used in the reproduction processing method of this embodiment is shown in FIG.
This apparatus includes an extruder 1, a cooling tank 2, a cutting machine 3, and a dryer 4. The extruder 1 is a twin-screw kneading extruder having a screw of L / D = 54, and is melted by a first seal ring 10 having a 40 mesh screen mesh and a second seal ring 11 having a 300 mesh screen mesh. 12, the chemical decomposition zone 13 and the kneading zone 14 are divided into three zones.
[0032]
A hopper 15 is provided at the front end of the melting region 12. A first inlet 16 for injecting a coating film decomposition accelerator is provided on the upstream side of the chemical decomposition zone 13, and a second inlet 17 for injecting a devolatilization aid is provided on the downstream side of the chemical decomposition zone 13. It has been. Further, the kneading zone 14 is provided with a devolatilization port 18 for removing volatile substances. A vacuum pump 50 is connected to the devolatilization port 18 via two coolers 5.
[0033]
In this extruder 1, the pressure in the cylinder is 10 to 100 (kg / cm ² The temperature of the kneaded product is adjusted to 240 to 270 ° C., and the coating film can be chemically decomposed without thermal degradation of the polypropylene. The processing amount was 80 to 120 (kg / h).
( Reference example 1 )
Using the above extruder, do the following: Reference example The reproduction processing method was performed.
[0034]
<Crushing process>
First, a polypropylene automobile bumper with a repaired urethane coating film used as a resin material with a coating film was prepared and pulverized into strips each having a side of about 5 to 10 mm using a pulverizer (not shown). The bumper resin base material contains about 0.1% by weight of BHT as an antioxidant.
[0035]
<Disassembly process>
Next, a fixed amount of the above-mentioned strip was supplied from the hopper 15 and the screw was driven. The fine piece is heated in the melting region 12 and heated by shear friction, and the resin base material is melted, conveyed while being melt-kneaded, passed through the first seal ring 10, and sent to the next chemical decomposition region 13. .
[0036]
With respect to the melt-kneaded material that has moved to the chemical decomposition zone 13, the pump 60 was driven to inject ethylenediamine, which is a coating film decomposition accelerator, from the first inlet 16. The amount of ethylenediamine injected is 5 to 7 parts by weight with respect to 100 parts by weight of the strip. In the chemical decomposition zone 13, the melt of fine pieces and ethylenediamine are kneaded, and the coating film is mechanically and chemically decomposed at high speed and reduced in molecular weight by the shearing force of the screw and ethylenediamine.
[0037]
In this chemical decomposition zone 13, the melt-kneaded product has a temperature equal to or higher than the boiling point (115 ° C.) of ethylenediamine. However, since it is at a high pressure, ethylenediamine tends to become liquid and is uniformly dispersed in the melt-kneaded product. Efficiently decomposes into a decomposed melt.
Decomposed coating film degradation products, ethylenediamine, antioxidants, etc. are relatively low molecules, so they are easy to vaporize, and the decomposition melt in the extruder is in a mixed state of liquid, solid, and gas. ing.
[0038]
Next, in the downstream area of the chemical decomposition zone 13, the pump 61 is driven to inject water from the second inlet 17. The amount of water injected was 0.04 parts by weight with respect to 100 parts by weight of the strip. Since the temperature of the decomposition melt is higher than the boiling point of water (100 ° C.), in the decomposition melt to which water has been added, the gas species further increase and the partial pressure of the gas component decreases.
[0039]
<Devolatile process>
Next, when the decomposition melt passes through the second seal ring 11, the pressure in the extruder 1 is reduced by driving the vacuum pump 50, and a relatively low molecular weight substance is vaporized. In addition, since water is also added, the types of gas components are increased and the partial pressure is reduced as compared with the case where water is not added. Therefore, since the system is directed to cancel the pressure gradient between the total pressure and the partial pressure, that is, the gas component is directed to exit from the kneaded product, the gas component contained in the decomposition melt is efficiently exhausted from the devolatilization port 18. The The exhaust component is separately captured by two coolers 5 arranged in series. In addition, the temperature of the decomposition melt in the position of the devolatilization port 18 is 200 degreeC.
[0040]
<Pelletization process>
In the kneading zone 14, the devolatilized recycled resin is further kneaded. After being extruded into a strand through a nozzle and cooled in the cooling tank 2, it was cut into pellets by a cutting machine 3 and dried by a drying machine 4 to obtain recycled resin pellets.
<Test>
A test piece having a predetermined shape was molded using the obtained recycled resin pellets, and coating was performed according to a conventional bumper coating process. The coating color was white in order to facilitate the evaluation of yellowing. And the heat resistance of a coating film, adhesiveness, and an outdoor weather resistance are tested, and a result is shown in Table 1 by 5-step evaluation. Table 1 also shows the test results of a new bumper.
[0041]
For heat resistance, a test piece on which a coating film was formed was heated at 80 ° C. for 240 hours, Δb value was calculated from colorimetric values before and after heating, and the range of 2 ≦ Δb was rank 1, 1.5 ≦ Δb < The range of 2 is rank 2, the range of 1 ≦ Δb <1.5 is rank 3, the range of 0.7 ≦ Δb <1 is rank 4, and the range of 0.7> Δb is rank 5. Of course, the higher the rank number, the smaller the color change and the better the heat resistance.
[0042]
Adhesion was evaluated by a cross-cut adhesion test according to JIS-K5400, and outdoor weather resistance was evaluated by measuring the color difference before and after exposure for 730 days outdoors.
( Example 1 )
The amount of water added from the second inlet 17 is 2.5 parts by weight with respect to 100 parts by weight of the strip. Reference example 1 The reproduction process was performed in the same manner as described above. And about the obtained recycled resin pellets Reference example 1 The test was conducted in the same manner as in Example 1, and the results are shown in Table 1.
[0043]
( Example 2 )
The amount of water added from the second injection port 17 is 8.5 parts by weight with respect to 100 parts by weight of the strip. Reference example 1 The reproduction process was performed in the same manner as described above. And about the obtained recycled resin pellets Reference example 1 The test was conducted in the same manner as in Example 1, and the results are shown in Table 1.
( Example 3 )
Instead of water, except that 2.5 parts by weight of a 0.1N aqueous hydrochloric acid solution was injected from the second inlet 17 to 100 parts by weight of the strip. Reference example 1 The reproduction process was performed in the same manner as described above. And about the obtained recycled resin pellets Reference example 1 The test was conducted in the same manner as in Example 1, and the results are shown in Table 1.
[0044]
(Comparative Example 1)
Except that no water was added from the second inlet 17. Reference example 1 The reproduction process was performed in the same manner as described above. And about the obtained recycled resin pellets Reference example 1 The test was conducted in the same manner as in Example 1, and the results are shown in Table 1.
[0045]
[Table 1]

From Table 1, Comparative Example 1 has low heat resistance and is unsuitable for practical use. Reference example 1 Then, the heat resistance rating is 3, which is at a practical level, Like the example It can be seen that the heat resistance improves as the amount of water added increases. In other words, yellowing resistance is improved by the addition of water, and the yellowing in the recycled resin pellets depends on whether the yellowing-causing substance is changed to a non-yellowing substance or the yellowing-causing substance is efficiently removed from the decomposition melt. It is clear that the amount of variable substances is reduced.
[0046]
Also Examples 1 and 2 When Example 3 It is also clear that the amount of yellowing-causing substances in the recycled resin pellets is further reduced by adding hydrochloric acid.
( Example 4 )
FIG. 2 shows a schematic configuration diagram of the apparatus used in this embodiment. This apparatus is provided with a vibrating screen 7 between the cutting machine 3 and the dryer 4 and the configuration of the dryer 4 is different. Reference example 1 The configuration is the same as that used in the apparatus.
[0047]
As shown in FIGS. 3 and 4, the vibrating screen 7 includes a base 70 and a vibrating container 72 held on the base 70 via a spring 71, and an ultraviolet lamp is provided on the inner surface of the lid 73 of the vibrating container 72. 8 are lined up. In the vibrating screen 7, the recycled resin pellets are charged into the vibrating container 72 from the charging port 74, and are carried to the outlet 76 while vibrating in the vibrating container 72 that is vibrated by driving the motor 75 provided on the base 70. It is pumped from the outlet 76 to the dryer 4. The recycled resin pellet is configured to be irradiated with ultraviolet rays from the ultraviolet lamp 8 while moving in the vibrating container 72.
[0048]
Further, as shown in FIG. 5, the dryer 4 includes an outer cylinder 40 and an inner cylinder 41, a hot air supply pipe 42 and a stirrer 43, and the ultraviolet lamp 8 is disposed between the outer cylinder 40 and the inner cylinder 41 in the height direction. It is lined up. The inner cylinder 41 is made of a resin or glass having a high ultraviolet transmittance. Hot air at 120 to 150 ° C. is supplied from the hot air supply pipe 42 into the inner cylinder 41. In this dryer 4, the recycled resin pellets are dried by hot air while being stirred by the stirrer 43, and during that time, ultraviolet rays are irradiated from the ultraviolet lamp 8.
[0049]
Except that the supply of water from the second inlet 17 was stopped using the above device. Reference example 1 The mixture was kneaded in the same manner as above, pelletized through the cooling tank 2 and the cutting machine 3, and then dried using the vibrating sieve 7 and the dryer 4 and irradiated with ultraviolet rays. The ultraviolet irradiation time is a total of 5 hours, and the irradiated ultraviolet intensity is 400 μW / cm. ² It is.
[0050]
Using the obtained recycled resin pellets, Reference example 1 Table 2 shows the results of testing in the same manner as above.
( Example 5 )
Except for supplying 2.5 parts by weight of water from the second inlet 17 to 100 parts by weight of the strip. Example 4 The reproduction process was performed in the same manner as described above. And using the obtained recycled resin pellets, Reference example 1 Table 2 shows the results of testing in the same manner as above.
[0051]
[Table 2]

Example 4 From the comparison with Comparative Example 1, it is clear that the heat resistance is significantly improved by ultraviolet irradiation, and it is clear that the amount of yellowing-causing substances in the recycled resin is reduced by ultraviolet irradiation. Also Example 4 to Example 5 Since it is superior in heat resistance, it can be seen that it is desirable to use water addition and ultraviolet irradiation in combination.
[0052]
【The invention's effect】
That is, according to the regeneration treatment method of the present invention, the residue of the yellowing cause substance is extremely reduced in the recycled resin. Accordingly, discoloration of the recycled product formed using the recycled resin is prevented, and the usage of the recycled resin is expanded.
[Brief description of the drawings]
FIG. 1 of the present invention Reference example It is a schematic diagram of the apparatus used by.
FIG. 2 of the present invention 4th to 5th It is a schematic diagram of the apparatus used in the Example.
FIG. 3 of the present invention 4th to 5th It is a front view of the vibration sieve of the apparatus used in the Example.
FIG. 4 of the present invention 4th to 5th It is a rear view of the lid | cover of the vibration sieve used in the Example.
FIG. 5 shows the present invention. 4th to 5th It is sectional drawing of the dryer of the apparatus used in the Example.
[Explanation of symbols]
1: Extruder 2: Cooling tank 3: Cutting machine
4: Dryer 7: Vibrating sieve 13: Chemical decomposition zone
16: First inlet 17: Second inlet 18: Devolatilizer

Claims (2)

Crushing a resin material with a coating film into a fine piece comprising a resin base material and a coating film, and contacting the strip with an alkaline coating film decomposition accelerator in a molten state to decompose the coating film. A method for regenerating a resin material with a coating film, comprising: a decomposition step for forming a decomposition melt; a devolatilization step for removing the decomposition product of the coating film and the coating film decomposition accelerator from the decomposition melt; And
In the decomposition step, after the strip is brought into contact with the coating film decomposition accelerator in a molten state, the coating film decomposition accelerator and a devolatilization aid that promotes devolatilization of the yellowing cause substance are attached to the coating A method for regenerating a resin material with a coating film , comprising adding to the decomposition melt in an amount of 0.1 to 20 parts by weight with respect to 100 parts by weight of the resin material. Crushing a resin material with a coating film into a fine piece comprising a resin base material and a coating film, and contacting the strip with an alkaline coating film decomposition accelerator in a molten state to decompose the coating film. A method for regenerating a resin material with a coating film, comprising: a decomposition step for forming a decomposition melt; a devolatilization step for removing the decomposition product of the coating film and the coating film decomposition accelerator from the decomposition melt; A method for regenerating a resin material with a coating film, comprising irradiating at least one of the decomposition melt and the regenerated resin after the devolatilization step with ultraviolet rays.

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