JP2004211002A - Manufacturing methods of colored expandable particle of thermoplastic resin and expansion molded product - Google Patents
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【０００１】
【技術分野】
本発明は着色した熱可塑性樹脂発泡粒子及び発泡成形体の製造方法に関する。
【０００２】
【従来技術】
従来より，ポリスチレン，ポリエチレン，ポリプロピレン等の熱可塑性樹脂からなる発泡成形体は，断熱材，緩衝材，包装容器等に用いられている。かかる発泡成形体は，独立気泡構造を有し，軽量で断熱性や緩衝性が良好である。
上記発泡成形体は，熱可塑性樹脂発泡粒子を金型に入れ加熱し，粒子表面を融着させることにより成形されたものである。通常，染料を添加していない上記発泡成形体は白色であるが，成形体の汚れ防止等のため，上記発泡成形体を着色することが行われている。
【０００３】
従来，着色した発泡成形体を製造する方法としては，主として次の３つの方法が知られている。
（１）通常実施されている白色の発泡成形体に，塗料等を塗布又はスプレーする方法，
（２）原料の熱可塑性樹脂のペレットを製造する際に，予め染料や顔料を練り込んでおき，これを用いて予備発泡粒子を製造後，該予備発泡粒子を金型内で加熱，発泡させて型内成形体とする方法，
（３）発泡性熱可塑性樹脂粒子を水に懸濁させ，この液中に染料と着色助剤を加えて粒子を着色し，得られた着色粒子を発泡成形する方法。
【０００４】
しかし，上記（１）の方法では，塗料の熱可塑性樹脂への接着力が弱く，塗布後に乾燥工程が必要で，また色ムラを生じ，塗装コストが高い等の問題があり，
また，上記（２）の方法では，予備発泡工程ないし貯槽ラインにおいて着色予備発泡粒子が混入し，これらのラインの切替や清掃をする必要があり，また各色の樹脂ペレットの在庫管理等が繁雑になるという問題があった。
また，上記（３）の方法では，水に懸濁させた染料は粒子中にその全てが吸収されず，水中に残存する。そのため，染料を多く必要とし，コストが高くなるという問題があった。また，染料を懸濁する水を多量に用いるため，設備が大型化すると共に，着色水の廃液が大量に発生するという問題があった。
【０００５】
上記（１）〜（３）の問題を解決するために，第４の方法として，染料又は顔料又はそれらの混合物を，ポリオレフィン系樹脂を溶解又は膨潤させることができる有機溶剤に溶解または分散混合させた着色用液体を準備し，このものとポリオレフィン系樹脂発泡粒子とを混合し，着色して，着色したポリオレフィン系樹脂発泡粒子を製造する方法が提案されている。（特許文献１参照）。
【０００６】
【特許文献１】
特公平６−７４３４２号公報（第２頁右欄第７行〜第３頁左欄第４０行）
【０００７】
【解決しようとする課題】
しかしながら，上記第４の方法で得られた着色したポリオレフィン系樹脂発泡粒子を成形すると，粒子表面に残留した染料または顔料によって，金型，粒子充填用のガン，離型ピンなどの成形設備が，着色汚染されてしまうという問題があった。
【０００８】
本発明は，かかる従来の問題点に鑑みてなされたもので，熱可塑性樹脂発泡粒子に着色剤を色ムラなく含浸させることができ，発泡成形時に成形設備を汚染することなく，色ムラが少ない，着色した熱可塑性樹脂発泡粒子及び発泡成形体の製造方法を提供しようとするものである。
【０００９】
【課題の解決手段】
第１の発明は，熱可塑性樹脂の発泡粒子と着色剤とを，実質的に無水雰囲気下で，上記熱可塑性樹脂の軟化温度−８０℃〜軟化温度の範囲で加熱し，上記発泡粒子に着色剤を含浸させることを特徴とする着色した熱可塑性樹脂発泡粒子の製造方法にある（請求項１）。
【００１０】
本発明の，着色した熱可塑性樹脂発泡粒子の製造方法においては，上記熱可塑性樹脂の軟化温度−８０℃〜軟化温度の範囲で，しかも実質的に無水雰囲気下で，上記発泡粒子と着色剤とを加熱している。
そのため，染料，顔料などの着色剤は，上記発泡粒子の内部へ効率良く含浸されていき，色ムラの発生が少ない着色した熱可塑性樹脂発泡粒子を得ることができる。また，着色剤が内部へ効率良く含浸されるため，着色剤が発泡粒子の表面部分に殆ど残留しない。
それ故，発泡体の成形時に成形設備を着色，汚染することもない。
【００１１】
次に，第２の発明は，着色した熱可塑性樹脂発泡粒子を金型内に充填し，加熱することにより，上記熱可塑性樹脂発泡粒子を加熱融着させて成形体を製造する方法において，上記着色した熱可塑性樹脂発泡粒子は，上記請求項１〜５のいずれか１項の方法により得られた着色した熱可塑性樹脂発泡粒子であることを特徴とする着色した熱可塑性樹脂発泡成形体の製造方法にある（請求項６）。
【００１２】
本発明においては，発泡成形体の原料である熱可塑性樹脂発泡粒子として，上記のようにして製造した着色した熱可塑性樹脂発泡粒子を用いている。
そのため，色ムラが少ない，着色された発泡成形体を製造することができる。そして，該熱可塑性樹脂発泡粒子は，表面に殆ど着色剤を付着していない。それ故，発泡成形時において成形設備を着色汚染することがない。
【００１３】
【発明の実施の形態】
第１の発明（請求項１）において，「実質的に無水雰囲気下」とは，熱可塑性樹脂発泡粒子に着色剤を含浸させる際に水を分散媒として使用しないことをいう。なお，着色加熱する容器内における水分量は，熱可塑性樹脂発泡粒子に対して１ｖｏｌ％以下とすることが好ましい。
また，実質的に無水雰囲気下で行なうため，水中懸濁による着色方法のように，水の体積を考慮して大きな密閉容器を用いる必要はなく，設備が大型化することもない。
【００１４】
また，熱可塑性樹脂の軟化温度−８０℃〜該熱可塑性樹脂の軟化温度の範囲内で加熱するので，熱可塑性樹脂発泡粒子に着色剤を色ムラ発生なく含浸させることができる。また，熱可塑性樹脂発泡粒子表面に余分な着色剤が残留することを防止することができるため，着色した熱可塑性樹脂発泡粒子を成形するときには，成形設備を汚染することがない。
【００１５】
上記加熱温度が「軟化温度−８０℃未満」という低い温度の場合には，加熱温度が低いため，着色剤の含浸が充分に進行せず，熱可塑性樹脂発泡粒子に所望の着色をムラなく施すことができない。一方，上記軟化温度を超える場合には，熱可塑性樹脂発泡粒子同士が融着してしまうおそれがある。
なお，好ましくは，熱可塑性樹脂の軟化温度−６０℃〜軟化温度の範囲である。更に好ましくは，熱可塑性樹脂の軟化温度−４０℃〜軟化温度の範囲である。
【００１６】
上記熱可塑性樹脂の軟化温度とは，「これを測定するためのシリンダに熱可塑性樹脂の発泡粒子を入れ，該シリンダ内の試料がピストンによって圧縮荷重を受けて変形し，シリンダ内の内部空隙が消失し，不均一な応力分布をもったまま外観均一な１個の透明体あるいは相になる温度」，すなわち測定試料が固体域から遷移域に移る時の温度のことである。
【００１７】
具体的には，例えば島津製作所社製フローテスタＣＦＴ−５００Ｃ形の昇温法（ダイス形状１ｍｍΦ×１０ｍｍＬ，予熱時間１０分，試験荷重５０ｋｇ，開始温度４０℃，昇温速度６℃／分）にて測定する。
そして，図１の流動曲線に示すように，各温度におけるピストンストロークをプロットし，ピストンの位置に明瞭な変化がある領域（固体域）から有限な時間内ではピストンの位置に明瞭な変化がなく，かつ試料のダイからの明らかな流出が認められない領域（遷移域）に移る時の温度を軟化温度とする。
【００１８】
本発明の発泡粒子として用いる熱可塑性樹脂としては，ポリエチレン，ポリプロピレン等のポリオレフィン系樹脂；アタクチックポリスチレン，シンジオタクチック，ポリスチレン，ゴム変性ポリスチレン，ＡＳ樹脂，ＡＢＳ樹脂等のポリスチレン系樹脂；ポリ塩化ビニル，ポリ塩化ビニリデン樹脂等のポリ塩化ビニル系樹脂及びポリ塩化ビニリデン系樹脂；ポリエチレンテレフタレート，ポリブチレンテレフタレート等の芳香族ポリエステル系樹脂；ポリエーテルイミド等のポリイミド系樹脂；ポリ乳酸，ポリエチレンサクシネート，ポリブチレンサクシネート，ポリカプロラクトン等の脂肪族ポリエステル系樹脂；ポリエチレンテレフタレート，ポリブチレンテレフタレート等の芳香族ポリエステル系樹脂；ＰＭＭＡ等のアクリル系樹脂；ポリサルホン，ポリエーテルサルホン等のポリサルホン系樹脂等，従来公知のものが使用できる。
【００１９】
これらの中，ポリオレフィン系樹脂，ポリスチレン系樹脂，脂肪族ポリエステル系樹脂が好ましい。
【００２０】
また，熱可塑性樹脂の発泡粒子の密度は，０．８〜２ｇ／ｃｍ３が好ましい。
この場合には，熱可塑性樹脂発泡粒子に，特に色ムラがなく均一に着色を施すことができる。
更に好ましくは，０．８〜１．２ｇ／ｃｍ３が良い。
【００２１】
また，熱可塑性樹脂のＳＰ値は１５〜２５ＭＰａ１／２が好ましい。この場合には，熱可塑性樹脂発泡粒子に着色剤を均一に含浸させる含浸剤として一般的に用いられている芳香族炭化水素類，脂肪族炭化水素類等の安価な溶剤を使用することができる。尚，ＳＰ値に関する詳細な説明は後述する。
更に好ましくは，熱可塑性樹脂のＳＰ値は１５〜２０ＭＰａ１／２が良い。
【００２２】
また，熱可塑性樹脂には，難燃剤，抗菌剤，帯電防止剤，酸化防止剤，光安定剤，紫外線吸収剤，防黴剤，安定剤，可塑剤，滑剤，高分子加工助剤，核剤，硬化剤，架橋剤等を含有していてもよい。
【００２３】
上記熱可塑性樹脂発泡粒子の製造方法としては，特に限定されるものではなく，ドカン法（特許庁昭和６３年３月編 図説ＩＰＣ［国際特許分類］），押出発泡法あるいは発泡ガスを含有させた熱可塑性樹脂粒子をスチーム等の適宜の加熱手段で加熱発泡させてもよい。
例えばドカン法の場合は，基材樹脂粒子を密閉容器内で水に分散させ，密閉容器内に揮発性膨張剤を供給し，該樹脂粒子の軟化点以上の温度に分散液を加熱した後，密閉容器の水面下に設けた吐出口を開放し，膨張剤が含浸された樹脂粒子を含む水分散液を密閉容器内の圧力より低い圧力の雰囲気下（大気圧）に放出することにより製造される。この際，空気や窒素ガスで容器内を加圧して放出を容易とすることが良い。
【００２４】
また，押出発泡法の場合，押出機内にて熱可塑性樹脂と揮発性発泡剤とを溶融混練後，冷却して，押出機先端に設けられたダイの細孔より押出発泡ストランドとして押出した後，該発泡ストランドをカッター等で適当な長さに切断することによって製造される。
【００２５】
また，熱可塑性樹脂発泡粒子の５０％粒子径は０．５〜６ｍｍが良い。更に好ましくは２〜４ｍｍが良い。また，発泡粒子の長径（Ｌ）と短径（ｄ）の比がＬ／ｄ＝５以下であることが好ましい。
５０％粒子径が６ｍｍより大きい場合やＬ／ｄが５を超える場合では，発泡粒が成形型の充填孔に詰まって充填不良になったり，成形品の粒子間隙が発生するおそれがある。５０％粒子径は，ＪＩＳ標準篩を用いて約２分間振とう機で振るい，各々の篩上の試料ビーズ重量を最小粒径から累積して，５０％に達したときの粒径値である。
【００２６】
また，上記着色剤としては，アゾ系染料，アンスラキノン系染料，アジン系染料，キノリン系染料，ペリノン系染料等の染料や，カーボンブラック，アゾ系顔料，銅フタロシアニン系顔料等の顔料が挙げられる。好ましくは，アンスラキノン系染料，ペリノン系染料等の染料が良い。この場合には，熱可塑性樹脂発泡粒子に特に所望の着色を施すことができる。
着色剤の量は熱可塑性樹脂発泡粒子１００重量部に対し，０．００１〜１重量部であることが好ましい。上記着色剤の量が０．００１重量部未満の場合には，熱可塑性樹脂発泡粒子に所望の着色を施すことができないおそれがある。一方，１重量部を超える場合には，熱可塑性樹脂発泡粒子に着色剤が完全に含浸されないおそれがある。
【００２７】
また，着色剤を熱可塑性樹脂発泡粒子に含浸させる時間は０．５時間以上であることが好ましい。０．５時間未満の場合には，熱可塑性樹脂発泡粒子に着色剤が充分に含浸されないおそれがある。
なお，着色剤の含浸時間を短縮させるには，熱可塑性樹脂発泡粒子同士が融着しない程度に容器内の温度をできるだけ高くすると良い。
【００２８】
また，撹拌混合操作は，例えば容器内の撹拌，混合が可能でかつ，加温可能であるものを用いることが好ましい。このような容器としては，例えば撹拌装置付きオートクレーブ，ヘンシェルミキサー，レディーゲミキサーやスーパーミキサー等が挙げられる。
【００２９】
次に，着色剤の含浸は，あらかじめ着色剤を上記発泡粒子に被覆または混合した後，含浸剤の存在下で混合して行ない，
上記含浸剤のＳＰ値は上記熱可塑性樹脂のＳＰ値±１０ＭＰａ１／２の範囲であることが好ましい（請求項２）。
【００３０】
この場合には，熱可塑性樹脂発泡粒子に，一層色ムラなく均一に着色を施すことができる。
上記含浸剤のＳＰ値が上記熱可塑性樹脂のＳＰ値±１０ＭＰａ１／２範囲より外れる場合には，熱可塑性樹脂発泡粒子に着色剤を充分に含浸させることができないおそれがある。なお，好ましくは，ＳＰ値±５ＭＰａ１／２の範囲である。
【００３１】
上記ＳＰ値とは，分子間の凝集エネルギー密度の平方根に相当するもので，この値は物理的に１ｃｍ３の液体を蒸発させるのに必要なエネルギー量を表している。尚，熱可塑性樹脂と含浸剤のＳＰ値が近いほど，熱可塑性樹脂と含浸剤との溶解や膨潤が起こる可能性がある。
熱可塑性樹脂及び含浸剤のＳＰ値算出方法は次のようであるが，「プラスチックデータブック」（工業調査会）の１−２−２８，「ポリマーハンドブック」（ＷＩＬＥＹ ＩＮＴＥＲＳＣＩＥＮＣＥ）に記載されている。
ＳＰ＝（△Ｅ／Ｖ）１／２＝ρ×ΣＦｓ／Ｍ
△ Ｅ：蒸発エネルギー，Ｖ：分子容
ρ：密度， Ｍ：分子量， Ｆｓ：Ｓｍａｌｌ氏の定数
【００３２】
例えば，グリセリントリステアレート（ρ＝０．８６，Ｍ＝８９１．５；（ＣＨ２ＯＣＯ（ＣＨ２）１６ＣＨ３）２ＣＨＯＣＯ（ＣＨ２）１６ＣＨ３）のＳＰ値を求めると，
【００３３】
また，上記含浸剤としては，ｎ−ブタン（１３．９），ｎ−ペンタン（１４．３），ｎ−ヘキサン（１４．９），ブチルステアレート（１５．３），流動パラフィン（１５．７），グリセリントリステアレート（１６．３），シクロヘキサン（１６．８），キシレン（１８．０），トルエン（１８．２），ベンゼン（１８．８），アセトン（２０．３），酢酸（２０．７），ブチルアルコール（２１．５），シクロヘキサノール（２３．３），エタノ―ル（２６．０），メタノール（２９．７）等の内，含浸剤のＳＰ値が熱可塑性樹脂粒子のＳＰ値±１０ＭＰａ１／２の範囲である有機化合物を用いることができる。これらの含浸剤は単独で又は混合して使用することができる。また，含浸剤は，好ましくは，含浸剤のＳＰ値が熱可塑性樹脂粒子のＳＰ値±５ＭＰａ１／２の範囲である。好ましくは，脂肪族炭化水素類または芳香族炭化水素類が良い。
【００３４】
次に，含浸剤の融点は，上記熱可塑性樹脂の軟化温度−８０℃以下であることが好ましい。（請求項３）。
この場合には，熱可塑性樹脂発泡粒子に，特に色ムラがなく均一に着色を施すことができる。
上記含浸剤の融点が熱可塑性樹脂の軟化温度−８０℃を超える場合には，熱可塑性樹脂発泡粒子に所望の着色を施すことができなくなるおそれがある。また，含浸剤の沸点は熱可塑性樹脂の軟化温度以下であることが好ましい。この場合には，熱可塑性樹脂発泡粒子に均一に着色を施すことができる。
【００３５】
次に，含浸剤は，上記発泡粒子１００重量部に対して０．０１〜１０重量部であることが好ましい。（請求項４）。
この場合には，熱可塑性樹脂発泡粒子に，一層色ムラなく，均一に着色を施すことができる。
上記含浸剤の量が０．０１重量部未満の場合には，熱可塑性樹脂発泡粒子に，所望の着色を施すことができなくなるおそれがある。一方，１０重量部を超える場合には，熱可塑性樹脂発泡粒子同士が融着してしまうおそれがある。好ましくは熱可塑性樹脂発泡粒子１００重量部に対して０．１〜５重量部である。
【００３６】
次に，着色剤の含浸は，帯電防止剤の存在下で行うことが好ましい。（請求項５）。
この場合には，熱可塑性樹脂発泡粒子に，一層色ムラなく均一に着色を施すことができる。着色剤を含浸する際，帯電防止剤存在下で行なうことにより，撹拌時における静電気発生を防止でき，一層色ムラなく均一に着色ができる。
【００３７】
帯電防止剤としては，例えば，ヒドロキシアルキルアミン，ヒドロキシアルキルモノエーテルアミン，グリセリン脂肪酸エステル，ポリオキシエチレンアルキルエーテル，ポリオキシエチレンアルキルエーテル等のノニオン系界面活性剤；アルキルスルホン酸塩，アルキルベンゼンスルホン酸塩，アルキルホスフェート等のアニオン系界面活性剤；テトラアルキルアンモニウム塩，トリアルキルベンジルアンモニウム塩等のカチオン系界面活性剤等が挙げられる。また，これらの帯電防止剤は，単独または混合して使用することもできる。
【００３８】
次に，上記第２の発明（請求項６）の製造方法において，上記のようにして得られた着色した熱可塑性樹脂発泡粒子は，通常の型成形方法，即ち金型内に充填，加熱し，加熱融着させた後冷却し，着色した熱可塑性樹脂発泡成形体として型内から取り出す。
【００３９】
その具体例を次に示す。
▲１▼ 熱可塑性樹脂発泡粒子を型内に過充填した後，発泡粒子の体積を圧縮し，次いでスチームで発泡樹脂粒子同士を加熱融着させる方法。
▲２▼ 熱可塑性樹脂粒子に揮発性発泡剤を予め含浸させて，発泡樹脂粒子に２次発泡性を付与し，これを型内に充填し，スチーム加熱し，成形する方法。
▲３▼ 発泡体粒子を密閉容器に入れ，次いで空気，窒素ガス等の無機ガスを室内に圧入することにより発泡樹脂粒子のセル内の圧力を高めて２次発泡性を付与し，この２次発泡性を付与した発泡樹脂粒子を型に充填し，スチーム加熱し，成形する方法。
また，上記▲１▼〜▲３▼の２つ以上を組み合わせる方法等がある。
【００４０】
次に，着色した熱可塑性樹脂発泡粒子を金型内に充填する際には，着色した熱可塑性樹脂発泡粒子の嵩容積を上記金型により５０〜９９％の範囲内に圧縮して，見かけ密度を高くした状態となし，
次いで上記加熱を行うことが好ましい。（請求項７）
【００４１】
これにより，加熱成形時において，発泡樹脂粒子の間の間隙量や発泡成形体の密度を調整することができ，所望する物性の着色された発泡成形体を得ることができる。
加熱前の金型内における発泡樹脂粒子の嵩容積が５０％より小さい状態にまで圧縮する場合は，殆ど間隙のない状態の発泡成形体を得ることができる。
一方，９９％よりも高い場合には，発泡樹脂粒子同士の接触面積が小さくなり，融着強度の弱い発泡成形体となるおそれがある。更に好ましくは，熱可塑性樹脂発泡粒子の嵩容積は，５０〜８０％とすることが良い。
【００４２】
上記のようにして得られた発泡成形体は，着色された断熱材，緩衝材，包装容器等に用いられる。
【００４３】
【実施例】
次に，着色した熱可塑性樹脂発泡粒子と発泡成形体を製造する実施例を示す。
（実施例１）
熱可塑性樹脂発泡粒子として三菱化学フォームプラスティック社製のポリプロピレン発泡粒子「ＥＰポールＥＡ４８０」（ポリプロピレンのＳＰ値１８．８，軟化温度１３１℃，密度０．９ｇ／ｃｍ３，発泡粒の５０％粒子径２．７ｍｍ，Ｌ／ｄ＝２）５０ｇと，青色染料としてオリエント化学工業製「Ｏｉｌ Ｂｌｕｅ６３０」（Ｓｏｌｖｅｎｔ Ｂｌｕｅ ３６，アンスラキノン系）０．１５ｇ（０．３重量部），帯電防止剤としてＮ，Ｎ−ビス（ヒドロキシエチル）アルキルアミン０．００５ｇ（０．０１重量部）を，内容積が約３Ｌの撹拌装置付きのオートクレーブ内に入れて１０分間撹拌混合した。
【００４４】
次いで，３０分かけて６０℃まで昇温し，含浸剤としてペンタン１．５ｇ（３重量部）を徐々に添加した。含浸剤添加後，更に６０℃にて３時間撹拌を続け，その後冷却して，青色に着色した熱可塑性樹脂発泡粒子を得た。
次に，着色した熱可塑性樹脂発泡粒子を発泡ポリプロピレン用成形機（ダイセン工業社製 ＥＰＶ−６００）の金型内に発泡樹脂粒子の体積を約３０％減ずるように圧縮充填（嵩密度６０ｋｇ／ｍ３）し，次いで水蒸気圧０．３５ＭＰａで加熱し，加熱融着させ，次いで冷却後，型内より発泡成形体を取り出し，縦１２０ｍｍ，横３００ｍｍ，厚み４０ｍｍの成形体を得た。
【００４５】
（実施例２）
本例では，実施例１の青色染料を赤色染料に変え，含浸剤をメタノール０．００２５ｇ（０．００５重量部）にする他は実施例１と同様にして着色した熱可塑性樹脂発泡粒子を作製し，該着色した熱可塑性樹脂発泡粒子を成形して発泡成形体を得た。なお，赤色染料としては，オリエント化学工業製「ＯＰＬＡＳ ＲＥＤ３３０」（Ｓｏｌｖｅｎｔ Ｒｅｄ １１１，アンスラキノン系）０．１５ｇ（０．３重量部）を用いた。
【００４６】
（実施例３）
本例では，実施例１の青色染料をカーボンブラック，含浸剤をシクロヘキサン０．５ｇ（１重量部）にする他は実施例１と同様にして着色した熱可塑性樹脂発泡粒子を作製し，該着色した熱可塑性樹脂発泡粒子を成形して発泡成形体を得た。なお，カーボンブラックとしては，ナカライ社製「カーボンブラック試薬」０．００５ｇ（０．０１重量部）を用いた。
【００４７】
（実施例４）
本例では，実施例１の青色染料をカーボンブラック，含浸温度を１２０℃に変え，含浸剤をシクロヘキサン０．５ｇ（１重量部）にする他は実施例１と同様にして着色した熱可塑性樹脂発泡粒子を作製し，該着色した熱可塑性樹脂発泡粒子を成形して発泡成形体を得た。なお，カーボンブラックとしては，ナカライ社製「カーボンブラック試薬」０．００５ｇ（０．０１重量部）を用いた。
【００４８】
（実施例５）
本例では，実施例１の青色染料を黒鉛，含浸温度を１２０℃に変え，含浸剤をトルエン０．５ｇ（１重量部）にする他は実施例１と同様にして着色した熱可塑性樹脂発泡粒子を作製し，該着色した熱可塑性樹脂発泡粒子を成形して発泡成形体を得た。なお，黒鉛としては，ナカライ社製「黒鉛試薬」０．００５ｇ（０．０１重量部）を用いた。
【００４９】
（実施例６）
本例では，含浸剤を添加しない他は実施例１と同様にして着色した熱可塑性樹脂発泡粒子を作製し，該着色した熱可塑性樹脂発泡粒子を成形して発泡成形体を得た。
【００５０】
（実施例７）
本例では，実施例１の含浸温度を１２０℃に変え，含浸剤を添加しない他は実施例１と同様にして着色した熱可塑性樹脂発泡粒子を作製し，該着色した熱可塑性樹脂発泡粒子を成形して発泡成形体を得た。
【００５１】
（実施例８）
本例では，実施例１の青色染料を黄色染料，含浸温度を１２０℃，熱可塑性樹脂発泡粒子を三菱化学フォームプラスティック社製のポリプロピレン発泡粒子「ＥＰポールＥＡ１９０」（ポリプロピレンのＳＰ値１８．８，軟化温度１３１℃，密度０．９ｇ／ｃｍ３，発泡粒の５０％平均粒径３．３ｍｍ，Ｌ／ｄ＝１．２）２０ｇ，含浸剤として流動パラフィン（松村石油研究所社製 モレスコホワイトＰ６０）３ｇ（１５重量部）に変え，帯電防止剤を添加しない他は実施例１と同様にして着色した熱可塑性樹脂発泡粒子を作製した。
【００５２】
得られた着色した熱可塑性樹脂発泡粒子を発泡ポリプロピレン用成形機（ダイセン工業社製 ＥＰＶ−６００）に発泡樹脂粒子の体積を約５０％減ずるように圧縮充填（嵩密度３０ｋｇ／ｍ３）し，次いで水蒸気圧０．２５ＭＰａで加熱融着させ，次いで冷却後，型内より発泡成形体を取り出し，縦１２０ｍｍ，横３００ｍｍ，厚み４０ｍｍの成形体を得た。
尚，黄色染料としては，オリエント化学工業製「ＯＰＬＡＳ ＹＥＬＬＯＷ１３６」（Ｓｏｌｖｅｎｔ Ｙｅｌｌｏｗ ３３，複素環系）０．２４ｇ（１．２重量部）を用いた。
【００５３】
（実施例９）
本例では，実施例１の熱可塑性樹脂発泡粒子を三菱化学フォームプラスティック社製の「スチロポールＪＱ２５０ＮＸ」（ポリスチレンのＳＰ値１８．６，軟化温度１１１℃，密度１．０５ｇ／ｃｍ３，発泡粒の５０％粒子径３．１ｍｍ，Ｌ／ｄ＝１）を３０Ｌのバッチ式発泡機で嵩密度２０ｇ／ｌに発泡したポリスチレン発泡粒子２０ｇ，含浸剤をペンタン０．６ｇ（３重量部）に変え，青色染料をオレンジ染料０．０１ｇ（０．０５重量部）にする他は実施例１と同様にして着色した熱可塑性樹脂発泡粒子を作製した。
【００５４】
得られた着色した熱可塑性樹脂発泡粒子を発泡ポリスチレン用成形機（ダイセン工業社製：ＶＳ−５００）で水蒸気圧０．０７ＭＰａで加熱融着して３００ｍｍ×７５ｍｍ×２５ｍｍの発泡成形体を得た。
尚，オレンジ染料としては，オリエント化学工業製「ＯＰＬＡＳ ＯＲＡＮＧＥ２３０」（Ｓｏｌｖｅｎｔ Ｏｒａｎｇｅ６０，ペリノン系）を用いた。
【００５５】
次に，上記実施例１〜９で得られた着色した熱可塑性樹脂発泡粒子及び発泡成形体の色ムラ，着色剤の含浸状態を下記の方法によって評価した。また，上記実施例１〜９の成形機の着色汚染度合いについて評価した。
【００５６】
（色ムラ）
上記着色した熱可塑性樹脂発泡粒子及び成形体の色ムラ（濃淡の差があるところ）を目視にて評価した。
上記熱可塑性樹脂発泡粒子及び成形体に実質的に濃淡の差はなく均一に見える場合を○，若干濃淡差が認められるが色ムラが少ない場合を△，濃淡差が明らかに認められるが色ムラが少ない場合を×として評価した。
その結果を表１に示す。
【００５７】
（含浸状態）
上記着色した熱可塑性樹脂発泡粒子及び成形体を白色紙に指で押しつけ，白色紙への染料の移行性を目視にて観察した。上記白色紙上に着色が全く観察されない場合を○とし，白色紙上に着色が若干観察される場合を△とし，白色紙上に着色が明らかに観察される場合を×として評価した。その結果を表１に示す。
【００５８】
（成形機の汚染度合い）
金型に染料の残留物が全く観察されない場合を○，染料の残留物が若干観察される場合を△，染料の残留物が明らかに観察される場合を×として評価した。その結果を表１に示す。
【００５９】
【表１】
表１より知られるごとく，実施例１〜９の製造方法により得られた着色した熱可塑性樹脂発泡粒子は，色ムラが少なく，染料の含浸性が良好であった。また，上記着色した熱可塑性樹脂発泡粒子を成形した発泡成形体も，色ムラが少なく，染料の含浸性が良好であった。
また，実施例１〜９の着色した熱可塑性樹脂発泡粒子の製造方法においては，装置を着色剤で着色汚染することはなく，特別に大きな装置を用いる必要もない。
【００６１】
次に，比較のために以下に示す比較例１〜２を行った。
（比較例１）
本例では，含浸温度を２０℃とし，含浸剤を添加せずに，他は実施例１と同様にして着色した熱可塑性樹脂発泡粒子を作製し，得られた着色した熱可塑性樹脂発泡粒子を成形して発泡成形体を得た。
【００６２】
（比較例２）
本例では，熱可塑性樹脂発泡粒子として三菱化学フォームプラスティック社製の「ＥＰポールＥＡ４８０」（ポリプロピレンのＳＰ値１８．８，軟化温度１３１℃，密度０．９ｇ／ｃｍ３，発泡粒の５０％粒子径２．７ｍｍ，Ｌ／ｄ＝２）５０ｇを用い，このものに含浸剤としてのトルエン０．０５ｇ（０．１重量部）に青色染料としてオリエント化学工業製「Ｏｉｌ Ｂｌｕｅ６３０」（Ｓｏｌｖｅｎｔ Ｂｌｕｅ ３６，アンスラキノン系）０．１５ｇ（０．３重量部）を準備した。
そして，これらを内容積が約３Ｌの撹拌装置付きのオートクレーブ内に入れ，含浸温度を２０℃で３０分間撹拌混合して，青色の熱可塑性樹脂発泡粒子を作製し，得られた着色した熱可塑性樹脂発泡粒子を成形して発泡成形体を得た。
【００６３】
次に，上記実施例１〜９の着色した熱可塑性樹脂発泡粒子と同様の方法により，上記比較例１〜２にて作製した着色した熱可塑性樹脂発泡粒子の色ムラ，着色剤の含浸状態を評価した。また，上記実施例１〜９の発泡成形体と同様の方法により，上記比較例１〜２にて得られた発泡成形体の色ムラ，着色剤の含浸状態を評価した。その結果を表２に示す。
【００６４】
【表２】
表２より知られるごとく，比較例１及び２にて得られた着色した熱可塑性樹脂発泡粒子及び成形体は，着色剤の含浸性が悪く，色ムラが発生していた。また，比較例１〜２の着色した熱可塑性樹脂発泡成形体の製造方法においては，成形機の金型が染料で汚染されていた。
【図面の簡単な説明】
【図１】熱可塑性樹脂の軟化温度測定法を説明する線図。[0001]
【Technical field】
The present invention relates to a method for producing colored thermoplastic resin foam particles and a foam molded article.
[0002]
[Prior art]
BACKGROUND ART Conventionally, foamed molded articles made of thermoplastic resins such as polystyrene, polyethylene, and polypropylene have been used for heat insulating materials, cushioning materials, packaging containers, and the like. Such a foamed molded article has a closed cell structure, is lightweight, and has good heat insulating properties and cushioning properties.
The foamed molded article is formed by placing thermoplastic resin foamed particles in a mold, heating and fusing the particle surfaces. Usually, the above-mentioned foamed molded article to which no dye is added is white, but the foamed molded article is colored in order to prevent contamination of the molded article.
[0003]
Conventionally, the following three methods are mainly known as methods for producing a colored foam molded article.
(1) A method of applying or spraying a paint or the like on a white foam molded body, which is usually performed,
(2) When manufacturing pellets of a thermoplastic resin as a raw material, dyes and pigments are kneaded in advance, and pre-expanded particles are manufactured using the kneaded materials. The pre-expanded particles are heated and expanded in a mold. To make a molded body in a mold,
(3) A method of suspending foamable thermoplastic resin particles in water, adding a dye and a coloring aid to the liquid to color the particles, and subjecting the obtained colored particles to foam molding.
[0004]
However, the method (1) has problems that the adhesive strength of the paint to the thermoplastic resin is weak, a drying step is required after coating, color unevenness occurs, and the coating cost is high.
In the above method (2), colored pre-foamed particles are mixed in the pre-foaming step or the storage tank line, and it is necessary to switch or clean these lines, and inventory management of resin pellets of each color becomes complicated. There was a problem of becoming.
In the above method (3), the dye suspended in water is not entirely absorbed in the particles but remains in the water. Therefore, there has been a problem that a large amount of dye is required and the cost is increased. Further, since a large amount of water for suspending the dye is used, the equipment becomes large, and there is a problem that a large amount of colored water waste liquid is generated.
[0005]
In order to solve the above problems (1) to (3), as a fourth method, a dye or pigment or a mixture thereof is dissolved or dispersed and mixed in an organic solvent capable of dissolving or swelling a polyolefin resin. There has been proposed a method of preparing a colored liquid for coloring, mixing the resulting liquid with expanded polyolefin resin particles, coloring the mixture, and producing colored expanded polyolefin resin particles. (See Patent Document 1).
[0006]
[Patent Document 1]
Japanese Patent Publication No. 6-74342 (page 7, right column, line 7 to page 3, left column, line 40)
[0007]
[Problem to be solved]
However, when the colored polyolefin-based resin foamed particles obtained by the above-mentioned fourth method are molded, the molding equipment such as a mold, a gun for filling the particles, a release pin, etc. is formed by the dye or pigment remaining on the particle surface. There was a problem that coloring and contamination would occur.
[0008]
The present invention has been made in view of such a conventional problem, and can impregnate a thermoplastic resin foam particle with a colorant without color unevenness, and does not contaminate molding equipment during foam molding and has less color unevenness. It is an object of the present invention to provide a method for producing colored thermoplastic resin foam particles and a foamed molded article.
[0009]
[Means for solving the problem]
According to a first aspect of the present invention, the foamed particles of the thermoplastic resin and the colorant are heated in a substantially anhydrous atmosphere in the range of the softening temperature of the thermoplastic resin −80 ° C. to the softening temperature to color the foamed particles. The present invention provides a method for producing colored thermoplastic resin foam particles, characterized by impregnating with an agent.
[0010]
In the method for producing colored thermoplastic resin foamed particles of the present invention, the foamed particles and the colorant are mixed with the thermoplastic resin in a softening temperature range of −80 ° C. to a softening temperature and in a substantially anhydrous atmosphere. Is heating.
Therefore, coloring agents such as dyes and pigments are efficiently impregnated into the interior of the expanded particles, and colored thermoplastic resin expanded particles with less occurrence of color unevenness can be obtained. Further, since the colorant is efficiently impregnated into the inside, the colorant hardly remains on the surface portion of the expanded particles.
Therefore, the molding equipment is not colored or contaminated during the molding of the foam.
[0011]
Next, a second invention provides a method of manufacturing a molded article by filling colored thermoplastic resin foam particles in a mold and heating the same to heat and fuse the thermoplastic resin foam particles. 6. A colored thermoplastic resin foam molded article, characterized in that the colored thermoplastic resin foam particles are colored thermoplastic resin foam particles obtained by the method according to any one of
[0012]
In the present invention, the colored thermoplastic resin foam particles produced as described above are used as the thermoplastic resin foam particles that are the raw materials of the foam molded article.
Therefore, it is possible to manufacture a colored foam molded article with less color unevenness. The thermoplastic resin expanded particles have almost no colorant attached to the surface. Therefore, there is no color contamination of the molding equipment during foam molding.
[0013]
BEST MODE FOR CARRYING OUT THE INVENTION
In the first invention (claim 1), "substantially in an anhydrous atmosphere" means that water is not used as a dispersion medium when impregnating the colorant into the foamed thermoplastic resin particles. In addition, it is preferable that the amount of water in the container to be colored and heated is 1 vol% or less based on the expanded thermoplastic resin particles.
In addition, since the reaction is performed in a substantially anhydrous atmosphere, there is no need to use a large closed container in consideration of the volume of water, unlike the coloring method using suspension in water, and the equipment does not become large.
[0014]
Further, since heating is performed within the range of the softening temperature of the thermoplastic resin −80 ° C. to the softening temperature of the thermoplastic resin, it is possible to impregnate the thermoplastic resin foam particles with the colorant without causing color unevenness. In addition, since it is possible to prevent an extra colorant from remaining on the surface of the thermoplastic resin foam particles, when molding the colored thermoplastic resin foam particles, there is no contamination of molding equipment.
[0015]
When the heating temperature is as low as "softening temperature-less than 80 ° C", the heating temperature is low, so that the impregnation of the coloring agent does not proceed sufficiently, and the desired coloring is applied to the thermoplastic resin foam particles evenly. I can't. On the other hand, if the softening temperature is exceeded, the thermoplastic resin foam particles may be fused together.
The softening temperature is preferably in the range of −60 ° C. to the softening temperature of the thermoplastic resin. More preferably, the softening temperature of the thermoplastic resin is in the range of −40 ° C. to the softening temperature.
[0016]
The softening temperature of the thermoplastic resin is defined as "the thermoplastic resin foam particles are put in a cylinder for measuring this, and the sample in the cylinder is deformed under the compressive load by the piston. This is the temperature at which the sample disappears and becomes a single transparent body or phase having a uniform appearance while having a non-uniform stress distribution, that is, the temperature at which the measurement sample moves from the solid region to the transition region.
[0017]
Specifically, for example, the temperature rising method of a flow tester CFT-500C manufactured by Shimadzu Corporation (die
Then, as shown in the flow curve in Fig. 1, the piston stroke at each temperature is plotted, and there is no clear change in the piston position within a finite time from the region where the piston position has a clear change (solid region). The temperature at which the sample moves to a region (transition region) where no apparent outflow of the sample from the die is observed is defined as a softening temperature.
[0018]
Examples of the thermoplastic resin used as the expanded particles of the present invention include polyolefin resins such as polyethylene and polypropylene; polystyrene resins such as atactic polystyrene, syndiotactic, polystyrene, rubber-modified polystyrene, AS resin and ABS resin; and polyvinyl chloride. Polyvinyl chloride resin such as polyvinylidene chloride resin and polyvinylidene chloride resin; aromatic polyester resin such as polyethylene terephthalate and polybutylene terephthalate; polyimide resin such as polyetherimide; polylactic acid, polyethylene succinate, poly Aliphatic polyester resins such as butylene succinate and polycaprolactone; aromatic polyester resins such as polyethylene terephthalate and polybutylene terephthalate; acrylic resins such as PMMA Polysulfone, polysulfone resins such as polyether sulfone or the like, is conventionally known ones can be used.
[0019]
Of these, polyolefin resins, polystyrene resins, and aliphatic polyester resins are preferred.
[0020]
The density of the expanded particles of the thermoplastic resin is 0.8 to 2 g / cm. 3 Is preferred.
In this case, the thermoplastic resin foamed particles can be uniformly colored without color unevenness.
More preferably, 0.8 to 1.2 g / cm 3 Is good.
[0021]
The SP value of the thermoplastic resin is 15 to 25 MPa. 1/2 Is preferred. In this case, inexpensive solvents such as aromatic hydrocarbons and aliphatic hydrocarbons generally used as an impregnating agent for uniformly impregnating the coloring particles into the thermoplastic resin foam particles can be used. . The detailed description of the SP value will be described later.
More preferably, the thermoplastic resin has an SP value of 15 to 20 MPa. 1/2 Is good.
[0022]
In addition, thermoplastic resins include flame retardants, antibacterial agents, antistatic agents, antioxidants, light stabilizers, ultraviolet absorbers, fungicides, stabilizers, plasticizers, lubricants, polymer processing aids, and nucleating agents. , A curing agent, a crosslinking agent, and the like.
[0023]
The method for producing the thermoplastic resin foam particles is not particularly limited, and includes a docan method (illustrated IPC [International Patent Classification], March 1988 by the Japan Patent Office), an extrusion foaming method, or a method containing a foaming gas. The thermoplastic resin particles may be heated and foamed by an appropriate heating means such as steam.
For example, in the case of the docan method, the base resin particles are dispersed in water in a closed container, a volatile expanding agent is supplied into the closed container, and the dispersion is heated to a temperature equal to or higher than the softening point of the resin particles. It is manufactured by opening a discharge port provided below the surface of a closed container and discharging an aqueous dispersion containing resin particles impregnated with a swelling agent under an atmosphere (atmospheric pressure) lower than the pressure in the closed container. You. At this time, it is preferable to pressurize the inside of the container with air or nitrogen gas to facilitate discharge.
[0024]
In the case of the extrusion foaming method, a thermoplastic resin and a volatile foaming agent are melt-kneaded in an extruder, then cooled and extruded as an extruded foam strand through pores of a die provided at the extruder tip. It is manufactured by cutting the foamed strand into an appropriate length with a cutter or the like.
[0025]
The 50% particle diameter of the expanded thermoplastic resin particles is preferably 0.5 to 6 mm. More preferably, it is 2 to 4 mm. Further, the ratio of the major axis (L) to the minor axis (d) of the expanded particles is preferably L / d = 5 or less.
If the 50% particle diameter is larger than 6 mm or L / d exceeds 5, the foamed particles may clog the filling holes of the mold, resulting in poor filling or a gap between the molded products. The 50% particle size is the particle size value when the sample beads on each sieve are shaken for about 2 minutes using a JIS standard sieve and the sample bead weight is accumulated from the minimum particle size and reaches 50%. .
[0026]
Examples of the colorant include dyes such as azo dyes, anthraquinone dyes, azine dyes, quinoline dyes, and perinone dyes, and pigments such as carbon black, azo pigments, and copper phthalocyanine pigments. . Preferably, dyes such as anthraquinone dyes and perinone dyes are used. In this case, the desired coloring can be particularly applied to the expanded thermoplastic resin particles.
The amount of the coloring agent is preferably from 0.001 to 1 part by weight based on 100 parts by weight of the expanded thermoplastic resin particles. If the amount of the coloring agent is less than 0.001 part by weight, it may not be possible to impart desired coloring to the expanded thermoplastic resin particles. On the other hand, if it exceeds 1 part by weight, the coloring agent may not be completely impregnated into the thermoplastic resin foam particles.
[0027]
The time for impregnating the thermoplastic resin foam particles with the colorant is preferably 0.5 hours or more. If the time is less than 0.5 hour, the coloring agent may not be sufficiently impregnated into the expanded thermoplastic resin particles.
In order to shorten the impregnation time of the coloring agent, the temperature in the container should be as high as possible so that the thermoplastic resin foam particles do not fuse together.
[0028]
In addition, for the stirring and mixing operation, it is preferable to use, for example, a stirring and mixing device capable of heating and heating the inside of the container. Examples of such a container include an autoclave with a stirring device, a Henschel mixer, a Ladyge mixer, a super mixer, and the like.
[0029]
Next, the impregnation with the coloring agent is performed by coating or mixing the coloring agent on the foamed particles in advance and then mixing in the presence of the impregnating agent.
The SP value of the impregnating agent is the SP value of the thermoplastic resin ± 10 MPa. 1/2 (Claim 2).
[0030]
In this case, the thermoplastic resin foamed particles can be colored evenly without color unevenness.
The SP value of the impregnating agent is the SP value of the thermoplastic resin ± 10 MPa. 1/2 If it is out of the range, the coloring agent may not be sufficiently impregnated into the thermoplastic resin foam particles. Preferably, the SP value is ± 5 MPa. 1/2 Range.
[0031]
The SP value is equivalent to the square root of the cohesive energy density between molecules, and is physically 1 cm. 3 Represents the amount of energy required to evaporate the liquid. The closer the SP value of the thermoplastic resin and the impregnating agent is, the more the dissolution and swelling of the thermoplastic resin and the impregnating agent may occur.
The method for calculating the SP value of the thermoplastic resin and the impregnating agent is as follows, which is described in “Plastic Data Book” (Industry Research Council) 1-228, “Polymer Handbook” (WILEY INTERSCIENCE).
SP = (△ E / V) 1/2 = Ρ × ΣFs / M
ΔE: evaporation energy, V: molecular volume
ρ: density, M: molecular weight, Fs: Small's constant
[0032]
For example, glycerin tristearate (ρ = 0.86, M = 891.5; (CH 2 OCO (CH 2 ) 16CH 3 ) 2 CHOCO (CH 2 ) 16 CH 3 ))
[0033]
Examples of the impregnating agent include n-butane (13.9), n-pentane (14.3), n-hexane (14.9), butyl stearate (15.3), and liquid paraffin (15.7). ), Glycerin tristearate (16.3), cyclohexane (16.8), xylene (18.0), toluene (18.2), benzene (18.8), acetone (20.3), acetic acid (20) .7), butyl alcohol (21.5), cyclohexanol (23.3), ethanol (26.0), methanol (29.7) and the like. SP value ± 10MPa 1/2 The organic compound having the range of the above can be used. These impregnating agents can be used alone or as a mixture. The impregnating agent preferably has an SP value of the impregnating agent of ± 5 MPa of the SP value of the thermoplastic resin particles. 1/2 Range. Preferably, aliphatic hydrocarbons or aromatic hydrocarbons are used.
[0034]
Next, the melting point of the impregnating agent is preferably equal to or lower than the softening temperature of the thermoplastic resin −80 ° C. (Claim 3).
In this case, the thermoplastic resin foamed particles can be uniformly colored without color unevenness.
If the melting point of the impregnating agent exceeds the softening temperature of the thermoplastic resin −80 ° C., it may not be possible to impart desired coloring to the expanded thermoplastic resin particles. Further, the boiling point of the impregnating agent is preferably equal to or lower than the softening temperature of the thermoplastic resin. In this case, the thermoplastic resin foam particles can be uniformly colored.
[0035]
Next, the amount of the impregnating agent is preferably 0.01 to 10 parts by weight based on 100 parts by weight of the expanded particles. (Claim 4).
In this case, the thermoplastic resin foam particles can be colored evenly without unevenness in color.
If the amount of the impregnating agent is less than 0.01 part by weight, it may not be possible to impart desired coloring to the expanded thermoplastic resin particles. On the other hand, if it exceeds 10 parts by weight, the thermoplastic resin foam particles may be fused together. Preferably, it is 0.1 to 5 parts by weight based on 100 parts by weight of the expanded thermoplastic resin particles.
[0036]
Next, the impregnation with the colorant is preferably performed in the presence of an antistatic agent. (Claim 5).
In this case, the thermoplastic resin foamed particles can be colored evenly without color unevenness. By impregnating the coloring agent in the presence of an antistatic agent, the generation of static electricity at the time of stirring can be prevented, and coloring can be performed more uniformly without color unevenness.
[0037]
Examples of the antistatic agent include nonionic surfactants such as hydroxyalkylamine, hydroxyalkylmonoetheramine, glycerin fatty acid ester, polyoxyethylene alkyl ether, and polyoxyethylene alkyl ether; alkyl sulfonate, alkylbenzene sulfonate And anionic surfactants such as alkyl phosphates; and cationic surfactants such as tetraalkylammonium salts and trialkylbenzylammonium salts. These antistatic agents can be used alone or in combination.
[0038]
Next, in the manufacturing method of the second invention (claim 6), the colored thermoplastic resin foam particles obtained as described above are filled in a usual molding method, that is, filled in a mold and heated. After being heated and fused, it is cooled and taken out of the mold as a colored thermoplastic resin foam molded article.
[0039]
Specific examples are shown below.
(1) A method in which the foamed thermoplastic resin particles are overfilled in a mold, the volume of the foamed particles is compressed, and then the foamed resin particles are heated and fused with steam.
{Circle around (2)} A method in which a thermoplastic resin particle is impregnated with a volatile foaming agent in advance to impart secondary foamability to the foamed resin particle, which is filled in a mold, steam-heated, and molded.
{Circle around (3)} The foam particles are put in a closed container, and then an inorganic gas such as air or nitrogen gas is injected into the room to increase the pressure in the cells of the foamed resin particles to impart secondary foaming property. A method in which foamed resin particles having foamability are filled into a mold, heated with steam, and molded.
There is a method of combining two or more of the above (1) to (3).
[0040]
Next, when filling the colored thermoplastic resin foam particles into a mold, the bulk volume of the colored thermoplastic resin foam particles is compressed to a range of 50 to 99% by the mold, and the apparent density is reduced. With and without
Next, it is preferable to perform the above heating. (Claim 7)
[0041]
Thereby, at the time of heat molding, the gap amount between the foamed resin particles and the density of the foamed molded article can be adjusted, and a colored foamed article having desired physical properties can be obtained.
When the foamed resin particles are compressed to a state in which the bulk volume of the foamed resin particles in the mold before heating is smaller than 50%, it is possible to obtain a foamed molded article having almost no gap.
On the other hand, if it is higher than 99%, the contact area between the foamed resin particles becomes small, and there is a possibility that the foamed molded article has a low fusion strength. More preferably, the bulk volume of the expanded thermoplastic resin particles is preferably 50 to 80%.
[0042]
The foam molded article obtained as described above is used for colored heat insulating materials, cushioning materials, packaging containers and the like.
[0043]
【Example】
Next, an example of producing colored thermoplastic resin foam particles and a foam molded article will be described.
(Example 1)
As foamed thermoplastic resin particles, foamed polypropylene particles “EP Poll EA480” manufactured by Mitsubishi Chemical Foam Plastic (SP value of polypropylene 18.8, softening temperature 131 ° C., density 0.9 g / cm) 3 50% of expanded granules, 2.7 mm in diameter, L / d = 2) 50 g, and 0.15 g (0.3 parts by weight) of "Oil Blue 630" (Solvent Blue 36, anthraquinone type) manufactured by Orient Chemical Industries as a blue dye ), 0.005 g (0.01 parts by weight) of N, N-bis (hydroxyethyl) alkylamine as an antistatic agent was placed in an autoclave having an internal volume of about 3 L and equipped with a stirrer, followed by stirring and mixing for 10 minutes.
[0044]
Next, the temperature was raised to 60 ° C. over 30 minutes, and 1.5 g (3 parts by weight) of pentane was gradually added as an impregnating agent. After the addition of the impregnating agent, stirring was further continued at 60 ° C. for 3 hours, and then the mixture was cooled to obtain expanded thermoplastic resin particles colored blue.
Next, the colored thermoplastic resin foam particles were compression-filled (bulk density 60 kg / m) into a mold of a foaming polypropylene molding machine (EPV-600 manufactured by Daisen Industries Co., Ltd.) so as to reduce the volume of the foam resin particles by about 30%. 3 ), Followed by heating at a steam pressure of 0.35 MPa, heat-sealing, and after cooling, the foamed molded product was taken out of the mold to obtain a molded product having a length of 120 mm, a width of 300 mm, and a thickness of 40 mm.
[0045]
(Example 2)
In this example, colored thermoplastic resin foamed particles were produced in the same manner as in Example 1 except that the blue dye of Example 1 was changed to a red dye, and the impregnating agent was changed to 0.0025 g (0.005 parts by weight) of methanol. Then, the colored thermoplastic resin foam particles were molded to obtain a foam molded article. As the red dye, 0.15 g (0.3 parts by weight) of "OPLAS RED330" (Solvent Red 111, anthraquinone type) manufactured by Orient Chemical Industries was used.
[0046]
(Example 3)
In this example, colored thermoplastic resin foamed particles were produced in the same manner as in Example 1 except that the blue dye of Example 1 was changed to carbon black and the impregnating agent was changed to 0.5 g (1 part by weight) of cyclohexane, and the coloring was performed. The expanded thermoplastic resin particles were molded to obtain an expanded molded article. As the carbon black, 0.005 g (0.01 parts by weight) of "Carbon Black Reagent" manufactured by Nakarai Co., Ltd. was used.
[0047]
(Example 4)
In this example, the thermoplastic resin was colored in the same manner as in Example 1 except that the blue dye of Example 1 was changed to carbon black, the impregnation temperature was changed to 120 ° C., and the impregnating agent was changed to 0.5 g (1 part by weight) of cyclohexane. Expanded particles were produced, and the colored thermoplastic resin expanded particles were molded to obtain an expanded molded article. As the carbon black, 0.005 g (0.01 parts by weight) of "Carbon Black Reagent" manufactured by Nakarai Co., Ltd. was used.
[0048]
(Example 5)
In this example, a thermoplastic resin foam colored in the same manner as in Example 1 except that the blue dye of Example 1 was changed to graphite, the impregnation temperature was changed to 120 ° C., and the impregnating agent was changed to 0.5 g (1 part by weight) of toluene. Particles were produced, and the colored thermoplastic resin foam particles were molded to obtain a foam molded article. As the graphite, 0.005 g (0.01 parts by weight) of "Graphite Reagent" manufactured by Nakarai Co., Ltd. was used.
[0049]
(Example 6)
In this example, colored thermoplastic resin foamed particles were produced in the same manner as in Example 1 except that no impregnating agent was added, and the colored thermoplastic resin foamed particles were molded to obtain a foam molded article.
[0050]
(Example 7)
In this example, colored thermoplastic resin foamed particles were produced in the same manner as in Example 1 except that the impregnation temperature in Example 1 was changed to 120 ° C., and the impregnating agent was not added. The molded article was obtained by molding.
[0051]
(Example 8)
In this example, the blue dye of Example 1 was a yellow dye, the impregnation temperature was 120 ° C., and the thermoplastic resin foam particles were polypropylene foam particles “EP Poll EA190” manufactured by Mitsubishi Chemical Foam Plastic (SP value of polypropylene 18.8, Softening temperature 131 ° C, density 0.9g / cm 3 20 g of 50% average particle size of expanded particles, 3.3 mm, L / d = 1.2), 3 g (15 parts by weight) of liquid paraffin (moresco white P60, manufactured by Matsumura Oil Research Institute) as an impregnating agent, and charged Except that no inhibitor was added, colored thermoplastic resin foamed particles were produced in the same manner as in Example 1.
[0052]
The obtained colored thermoplastic resin foam particles are compression-filled (bulk density 30 kg / m) into a foaming polypropylene molding machine (EPV-600 manufactured by Daisen Industries Co., Ltd.) so as to reduce the volume of the foam resin particles by about 50%. 3 ), And then heat-fused at a steam pressure of 0.25 MPa. After cooling, the foamed molded product was taken out of the mold to obtain a molded product having a length of 120 mm, a width of 300 mm, and a thickness of 40 mm.
As the yellow dye, 0.24 g (1.2 parts by weight) of "OPLAS YELLOW 136" (Solvent Yellow 33, heterocyclic system) manufactured by Orient Chemical Industries was used.
[0053]
(Example 9)
In this example, the thermoplastic resin foamed particles of Example 1 were converted to “Styropol JQ250NX” (manufactured by Mitsubishi Chemical Foam Plastic Co., Ltd.) (SP value of polystyrene 18.6, softening temperature 111 ° C., density 1.05 g / cm). 3 , 50% of expanded particles, 3.1 mm, L / d = 1) were foamed to a bulk density of 20 g / l with a 30 L batch type foaming machine, 20 g of polystyrene foam particles, and impregnant 0.6 g of pentane (3 parts by weight) ), And colored thermoplastic resin expanded particles were produced in the same manner as in Example 1 except that the blue dye was changed to 0.01 g (0.05 parts by weight) of the orange dye.
[0054]
The obtained colored thermoplastic resin foam particles were heated and fused at a steam pressure of 0.07 MPa using a foaming polystyrene molding machine (VS-500, manufactured by Daisen Industries Co., Ltd.) to obtain a foam molded article of 300 mm × 75 mm × 25 mm. .
As the orange dye, "OPLAS ORANGE230" (solvent orange 60, perinone type) manufactured by Orient Chemical Industries was used.
[0055]
Next, the colored thermoplastic resin foam particles obtained in Examples 1 to 9 and the color unevenness of the foam molded article and the impregnation state of the colorant were evaluated by the following methods. Further, the degree of coloring contamination of the molding machines of Examples 1 to 9 was evaluated.
[0056]
(Color unevenness)
The color unevenness (where there is a difference in light and shade) of the colored thermoplastic resin foam particles and the molded article was visually evaluated.
The case where the thermoplastic resin foam particles and the molded article seem to be uniform without substantial difference in shading is indicated by “○”, the slight shading difference is recognized but the color unevenness is small, and the shading difference is clearly recognized but the color unevenness is recognized. Was evaluated as x when there was little.
Table 1 shows the results.
[0057]
(Impregnated state)
The colored thermoplastic resin foam particles and the molded product were pressed against white paper with a finger, and the dye transferability to the white paper was visually observed. The case where no coloring was observed on the white paper was evaluated as ○, the case where slight coloring was observed on white paper was evaluated as Δ, and the case where coloring was clearly observed on white paper was evaluated as x. Table 1 shows the results.
[0058]
(Degree of contamination of molding machine)
The case where no dye residue was observed in the mold was evaluated as ○, the case where a slight dye residue was observed was evaluated as Δ, and the case where a dye residue was clearly observed was evaluated as ×. Table 1 shows the results.
[0059]
[Table 1]
As can be seen from Table 1, the colored thermoplastic resin foam particles obtained by the production methods of Examples 1 to 9 had little color unevenness and good dye impregnation. In addition, the foamed molded product obtained by molding the colored thermoplastic resin foamed particles also had little color unevenness and good dye impregnation.
Further, in the method for producing colored thermoplastic resin foamed particles of Examples 1 to 9, there is no need to use a particularly large device without coloring and contaminating the device with a colorant.
[0061]
Next, Comparative Examples 1 and 2 shown below were performed for comparison.
(Comparative Example 1)
In this example, the impregnation temperature was set to 20 ° C., and no colored impregnating agent was added. The other steps were the same as in Example 1 to produce colored thermoplastic resin foam particles. The molded article was obtained by molding.
[0062]
(Comparative Example 2)
In this example, "EP Poll EA480" (manufactured by Mitsubishi Chemical Foam Plastic Co., Ltd.) (SP value of polypropylene: 18.8, softening temperature: 131 ° C., density: 0.9 g / cm) was used as thermoplastic resin foam particles. 3 , 50% particle size of expanded particles 2.7 mm, L / d = 2) 50 g, and 0.05 g (0.1 parts by weight) of toluene as an impregnating agent and a blue dye “Oil” manufactured by Orient Chemical Industries "Blue630" (Solvent Blue 36, anthraquinone type) 0.15 g (0.3 parts by weight) was prepared.
Then, these were put into an autoclave with a stirrer having an internal volume of about 3 L, and stirred and mixed at an impregnation temperature of 20 ° C. for 30 minutes to produce blue thermoplastic resin foam particles, and the obtained colored thermoplastic resin was obtained. The expanded resin particles were molded to obtain an expanded molded article.
[0063]
Next, in the same manner as in the colored thermoplastic resin foam particles of Examples 1 to 9, the color unevenness of the colored thermoplastic resin foam particles produced in Comparative Examples 1 and 2 and the impregnation state of the coloring agent were determined. evaluated. Further, in the same manner as in the foamed molded articles of Examples 1 to 9, the color unevenness and the impregnation state of the colorant of the foamed molded articles obtained in Comparative Examples 1 and 2 were evaluated. Table 2 shows the results.
[0064]
[Table 2]
As can be seen from Table 2, the colored thermoplastic resin foam particles and molded articles obtained in Comparative Examples 1 and 2 were poor in impregnation of the colorant and caused color unevenness. Further, in the method for producing a colored thermoplastic resin foam molded article of Comparative Examples 1 and 2, the mold of the molding machine was contaminated with the dye.
[Brief description of the drawings]
FIG. 1 is a diagram illustrating a method for measuring a softening temperature of a thermoplastic resin.
Claims (7)
上記含浸剤のＳＰ値は上記熱可塑性樹脂のＳＰ値±１０ＭＰａ１／２の範囲であることを特徴とする着色した熱可塑性樹脂発泡粒子の製造方法。2. The method according to claim 1, wherein the impregnating of the coloring agent is performed by coating or mixing the coloring agent on the expanded particles in advance and then mixing in the presence of the impregnating agent.
A method for producing colored thermoplastic resin foam particles, wherein the SP value of the impregnating agent is in the range of the SP value of the thermoplastic resin ± 10 MPa 1/2 .
上記着色した熱可塑性樹脂発泡粒子は，上記請求項１〜５のいずれか１項の方法により得られた着色した熱可塑性樹脂発泡粒子であることを特徴とする着色した熱可塑性樹脂発泡成形体の製造方法。A method for manufacturing a molded article by filling the thermoplastic resin foamed particles into a mold and heating the resin to heat and fuse the thermoplastic resin foamed particles,
A colored thermoplastic resin foam molded article characterized in that the colored thermoplastic resin foamed particles are colored thermoplastic resin foamed particles obtained by the method according to any one of claims 1 to 5. Production method.
次いで上記加熱を行うことを特徴とする着色した熱可塑性樹脂発泡成形体の製造方法。In claim 6, when filling the colored thermoplastic resin foam particles into the mold, the bulk volume of the colored thermoplastic resin foam particles is compressed to 50 to 99% by the mold, With and without apparent density
Next, the above-mentioned heating is performed, and a method for producing a colored thermoplastic resin foam molded article is provided.
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| CN108715648A (en) * | 2016-05-19 | 2018-10-30 | 晋江国盛新材料科技有限公司 | A kind of spray painting painting methods of TPU expanded beads formed body |
| CN109081937A (en) * | 2016-05-19 | 2018-12-25 | 晋江国盛新材料科技有限公司 | A kind of retouching for TPU expanded bead formed body paints color method |
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