JP4179882B2 - Colored thermoplastic resin foam particles and method for producing foam molded article - Google Patents
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Description
【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，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することによって，
発泡粒子に着色剤を含浸させる着色した熱可塑性樹脂発泡粒子の製造方法であって，
上記発泡粒子にあらかじめ着色剤を被覆または混合した後，
ＳＰ値が上記熱可塑性樹脂のＳＰ値±１０ＭＰａ 1/2 の範囲の含浸剤を混合した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】
本発明においては，あらかじめ発泡粒子に着色剤を被覆又は混合した後，含浸剤を添加して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，しかも上記含浸剤は特定のＳＰ値のものを用いて，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１〜４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５）。
【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，「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，上記着色は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，上記加熱は，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。
【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２）。
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，含浸剤の量は，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３）。
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。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５）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６）
【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】
（参考例１）
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】
（参考例２）
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】
（参考例３）
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１，３〜５，８，９及び参考例１，２，３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，参考例における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１，３〜５，８，９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１，３〜５，８，９における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１，３〜５，８，９における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 colored thermoplastic resin foam particle and a method for producing a foam molded article.
[0002]
[Prior 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 insulation and buffering properties.
The foamed molded article is formed by placing thermoplastic resin foam particles in a mold and heating them to fuse the particle surfaces. Usually, the foamed molded product to which no dye is added is white, but the foamed molded product is colored to prevent the molded product from being stained.
[0003]
Conventionally, the following three methods are mainly known as methods for producing a colored foamed molded article.
(1) A method of applying or spraying a paint or the like to a white foam molded body, which is normally performed,
(2) When producing pellets of raw thermoplastic resin, dyes and pigments are kneaded in advance, and pre-foamed particles are produced using this, and then the pre-foamed particles are heated and foamed in a mold. A method of forming a molded body in a mold,
(3) A method in which foamable thermoplastic resin particles are suspended in water, a dye and a coloring aid are added to the liquid to color the particles, and the resulting colored particles are foam-molded.
[0004]
However, the method (1) has problems such that the adhesive strength of the paint to the thermoplastic resin is weak, a drying process is required after application, color unevenness occurs, and the coating cost is high.
In the method (2), colored pre-foamed particles are mixed in the pre-foaming process or storage line, and it is necessary to switch or clean these lines, and the inventory management of resin pellets of each color is complicated. There was a problem of becoming.
In the method (3), the dye suspended in water is not completely absorbed in the particles but remains in water. For this reason, there is a problem that a large amount of dye is required and the cost becomes high. In addition, since a large amount of water in which the dye is suspended is used, the size of the equipment is increased, and a large amount of colored water wastewater is generated.
[0005]
In order to solve the 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 for producing colored polyolefin resin expanded particles by preparing a colored liquid, mixing this with polyolefin resin expanded particles and coloring them. (See Patent Document 1).
[0006]
[Patent Document 1]
Japanese Patent Publication No. 6-74342 (page 2, right column, line 7 to page 3, left column, line 40)
[0007]
[Problems to be solved]
However, when the colored polyolefin resin expanded particles obtained by the above fourth method are molded, the molding equipment such as a mold, a particle filling gun, a release pin, etc., depending on the dye or pigment remaining on the particle surface, There was a problem of being colored and contaminated.
[0008]
The present invention has been made in view of such conventional problems, and allows the thermoplastic resin foam particles to be impregnated with a colorant without color unevenness, with little color unevenness without contaminating molding equipment during foam molding. The present invention intends to provide a method for producing colored thermoplastic resin expanded particles and expanded molded articles.
[0009]
[Means for solving problems]
The first invention is a foamed thermoplastic resin particle.And colorants,Under an anhydrous atmosphere,
Heating in the range of softening temperature of the thermoplastic resin from -80 ° C to softening temperatureBy,
A method for producing colored thermoplastic resin foam particles in which foam particles are impregnated with a colorant,
After coating or mixing the above expanded particles with a colorant in advance,
SP value of the thermoplastic resin is SP value ± 10 MPa 1/2 Mixed with a range of impregnating agentsIt is in the manufacturing method of the colored thermoplastic resin expanded particle characterized by the above-mentioned (Claim 1).
[0010]
Main departureClearlyIn theAfter coating or mixing colorant with foamed particles in advance, add impregnating agent in an anhydrous atmosphereOf the above thermoplastic resin"Softening temperature-80 ℃"In the softening temperature rangeUse the impregnating agent with a specific SP valueThe foamed particles and the colorant are heated.
Therefore, coloring agents such as dyes and pigments can be efficiently impregnated into the foamed particles, and colored thermoplastic resin foamed particles with less color unevenness can be obtained. Further, since the colorant is efficiently impregnated into the interior, the colorant hardly remains on the surface portion of the expanded particles.
Therefore, the molding equipment is not colored or contaminated when molding the foam.
[0011]
Next, the second invention is a method for producing a molded product by filling the thermoplastic resin foam particles in a mold and heating, thereby heat-sealing the thermoplastic resin foam particles.
The colored thermoplastic resin expanded particles are the above-mentioned claims 1 to 3.4A method for producing a colored thermoplastic resin foam molded article, wherein the foamed colored thermoplastic resin particles are obtained by the method according to any one of claims 1 to 6.5).
[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 material of the foam molded article.
Therefore, it is possible to produce a colored foamed molded body with little 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]
DETAILED DESCRIPTION OF THE INVENTION
In the first invention (Claim 1),"Nothing“Under water atmosphere” means that water is not used as a dispersion medium when the foamed thermoplastic resin particles are impregnated with a colorant. The water content in the colored and heated container is preferably 1 vol% or less with respect to the thermoplastic resin foam particles.
Also,The above coloring isSince it is carried out in an anhydrous atmosphere, there is no need to use a large sealed container in consideration of the volume of water, unlike the coloring method by suspension in water, and the equipment does not become large.
[0014]
Also,The above heatingOf thermoplastic resin"Softening temperature-80 ℃"~ Of the thermoplastic resin"Softening temperature"Therefore, the thermoplastic resin foam particles can be impregnated with the colorant without causing color unevenness. In addition, since it is possible to prevent excess colorant from remaining on the surface of the foamed thermoplastic resin particles, the molding equipment is not contaminated when the colored thermoplastic resin foam particles are molded.
[0015]
The heating temperature is “softening temperature−80 ° C."When the temperature is lower than the above, the heating temperature is low, so that the impregnation with the colorant does not proceed sufficiently, and the desired foaming cannot be uniformly applied to the thermoplastic resin foam particles. On the other hand, if the softening temperature is exceeded, the thermoplastic resin foam particles may be fused.
In addition, Preferably, it is the range of softening temperature-60 degreeC-softening temperature of a thermoplastic resin. More preferably, it is in the range of the softening temperature of the thermoplastic resin from −40 ° C. to the softening temperature.
[0016]
The softening temperature of the above-mentioned thermoplastic resin means that “foamed particles of thermoplastic resin are put in a cylinder for measuring this, and the sample in the cylinder is deformed by a compression load by the piston, and the internal void in the cylinder is It is the temperature at which it disappears and becomes a single transparent body or phase with uniform appearance with 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, a temperature test method of a flow tester CFT-500C manufactured by Shimadzu Corporation (die shape 1 mmΦ × 10 mmL, preheating time 10 minutes, test load 50 kg, starting temperature 40 ° C., heating rate 6 ° C./min) To measure.
Then, as shown in the flow curve of 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). , And the temperature at which the sample moves to a region (transition region) where no clear outflow from the die is observed, is the 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; Polyvinyl chloride resins such as polyvinylidene chloride and polyvinylidene chloride resins; Aromatic polyester resins such as polyethylene terephthalate and polybutylene terephthalate; Polyimide resins 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 preferable.
[0020]
The density of the expanded particles of the thermoplastic resin is 0.8-2 g / cm.ThreeIs preferred.
In this case, the thermoplastic resin foam particles can be colored uniformly without any particular color unevenness.
More preferably, 0.8 to 1.2 g / cmThreeIs good.
[0021]
The SP value of the thermoplastic resin is 15-25 MPa.1/2Is preferred. In this case, inexpensive solvents such as aromatic hydrocarbons and aliphatic hydrocarbons generally used as an impregnating agent for uniformly impregnating thermoplastic resin foam particles with a colorant can be used. . Detailed description regarding the SP value will be described later.
More preferably, the SP value of the thermoplastic resin is 15 to 20 MPa.1/2Is good.
[0022]
Thermoplastic resins include flame retardants, antibacterial agents, antistatic agents, antioxidants, light stabilizers, UV absorbers, antifungal agents, stabilizers, plasticizers, lubricants, polymer processing aids, and nucleating agents. Further, it may contain a curing agent, a crosslinking agent and the like.
[0023]
The method for producing the thermoplastic resin foamed particles is not particularly limited, and the docan method (Japan Patent Office, March 1988, Illustrated IPC [International Patent Classification]), extrusion foaming method or foaming gas was included. 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 sealed container, a volatile expansion agent is supplied into the sealed 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 under the water surface of a sealed container and releasing an aqueous dispersion containing resin particles impregnated with an expanding agent into an atmosphere (atmospheric pressure) at a pressure lower than the pressure in the sealed container. The At this time, it is preferable to facilitate the discharge by pressurizing the inside of the container with air or nitrogen gas.
[0024]
In the case of the extrusion foaming method, the thermoplastic resin and the volatile foaming agent are melt-kneaded in the extruder, cooled, and extruded as extruded foam strands from the pores of the die provided at the tip of the extruder. The foamed strand is produced by cutting it into an appropriate length with a cutter or the like.
[0025]
The 50% particle diameter of the thermoplastic resin expanded particles is preferably 0.5 to 6 mm. More preferably, the thickness is 2 to 4 mm. The ratio of the major axis (L) to the minor axis (d) of the expanded particles is preferably L / d = 5 or less.
When the 50% particle diameter is larger than 6 mm or when L / d exceeds 5, there is a possibility that the foamed particles are clogged in the filling hole of the molding die, resulting in poor filling or particle gaps in the molded product. The 50% particle size is a particle size value when 50% is obtained by accumulating the sample bead weight on each sieve from the minimum particle size by shaking with a JIS standard sieve for about 2 minutes. .
[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. . A dye such as anthraquinone dye or perinone dye is preferable. In this case, the thermoplastic resin foam particles can be particularly desired to be colored.
The amount of the colorant is preferably 0.001 to 1 part by weight with respect to 100 parts by weight of the thermoplastic resin foam particles. When the amount of the colorant is less than 0.001 part by weight, the thermoplastic resin foam particles may not be colored as desired. On the other hand, if it exceeds 1 part by weight, the thermoplastic resin foam particles may not be completely impregnated with the colorant.
[0027]
The time for impregnating the thermoplastic resin expanded particles with the colorant is preferably 0.5 hours or more. If it is less than 0.5 hours, the thermoplastic resin foam particles may not be sufficiently impregnated with the colorant.
In order to shorten the impregnation time of the colorant, it is preferable to raise the temperature in the container as much as possible so that the thermoplastic resin expanded particles are not fused together.
[0028]
Moreover, it is preferable to use what can stir and mix in a container, for example, and can be heated for stirring mixing operation. Examples of such containers include an autoclave with a stirrer, a Henschel mixer, a ladyge mixer, and a super mixer.
[0029]
Next, impregnation of the colorant is performed by previously coating or mixing the colorant with the foamed particles and then mixing in the presence of the impregnant.
The SP value of the impregnating agent is the SP value of the thermoplastic resin ± 10 MPa.1/2In the rangeThe
[0030]
In this case, it is possible to uniformly color the thermoplastic resin expanded particles without color unevenness.
The SP value of the impregnating agent is the SP value of the thermoplastic resin ± 10 MPa.1/2If it is out of the range, the thermoplastic resin expanded particles may not be sufficiently impregnated with the colorant. Preferably, SP value ± 5 MPa1/2Range.
[0031]
The SP value corresponds to the square root of the cohesive energy density between molecules, and this value is physically 1 cm.ThreeRepresents the amount of energy required to evaporate the liquid. Note that the closer the SP values of the thermoplastic resin and the impregnating agent are, the more likely the thermoplastic resin and the impregnating agent will dissolve or swell.
The SP value calculation method of the thermoplastic resin and the impregnating agent is as follows, but is described in “Plastic Data Book” (Industry Research Council) 1-228, “Polymer Handbook” (WILEY INTERSCIENCE).
SP = (△ E / V)1/2= Ρ × ΣFs / M
E: 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;
(CH2OCO (CH2) 16CHThree)2CHOCO (CH2)16CHThree) SP value of
[0033]
Examples of the impregnating agent include n-butane (13.9), n-pentane (14.3), n-hexane (14.9), butyl stearate (15.3), 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), etc., the SP value of the impregnating agent is that of the thermoplastic resin particles. SP value ± 10 MPa1/2The organic compound which is the range of can be used. These impregnating agents can be used alone or in combination. The impregnating agent preferably has an SP value of the impregnating agent of SP value of thermoplastic resin particles ± 5 MPa.1/2Range. Preferably, aliphatic hydrocarbons or aromatic hydrocarbons are used.
[0034]
Next, the melting point of the impregnating agent is preferably not higher than the softening temperature of the thermoplastic resin of −80 ° C. (Claims2).
In this case, the thermoplastic resin foam particles can be colored uniformly without any particular color unevenness.
If the melting point of the impregnating agent exceeds the softening temperature of the thermoplastic resin of −80 ° C., the thermoplastic resin foam particles may not be able to be colored. The boiling point of the impregnating agent is preferably not higher than the softening temperature of the thermoplastic resin. In this case, the thermoplastic resin foam particles can be uniformly colored.
[0035]
Next, impregnating agentAmount ofIs preferably 0.01 to 10 parts by weight with respect to 100 parts by weight of the expanded particles. (Claims3).
In this case, it is possible to uniformly color the thermoplastic resin expanded particles without any color unevenness.
When the amount of the impregnating agent is less than 0.01 part by weight, there is a possibility that the thermoplastic resin foam particles cannot be colored as desired. On the other hand, if it exceeds 10 parts by weight, the thermoplastic resin foam particles may be fused together. Preferably it is 0.1-5 weight part with respect to 100 weight part of thermoplastic resin expanded particles.
[0036]
Next, the impregnation with the colorant is preferably performed in the presence of an antistatic agent. (Claims4).
In this case, it is possible to uniformly color the thermoplastic resin expanded particles without color unevenness. When impregnating with a colorant, by carrying out in the presence of an antistatic agent, generation of static electricity during stirring can be prevented, and even coloration can be achieved evenly.
[0037]
Examples of the antistatic agent include nonionic surfactants such as hydroxyalkylamine, hydroxyalkyl monoetheramine, glycerin fatty acid ester, polyoxyethylene alkyl ether, polyoxyethylene alkyl ether; alkyl sulfonate, alkyl benzene 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, the second invention (claim)5In the production method, the colored thermoplastic resin foam particles obtained as described above are colored in the usual mold molding method, that is, filled in a mold, heated, heat-fused, cooled, and colored. It is taken out from the mold as a thermoplastic resin foam molding.
[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 heat-sealed with steam.
(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.
(3) Put the foam particles in a sealed container, and then pressurize the interior of the cell with foamed resin particles by injecting an inorganic gas such as air or nitrogen gas into the chamber to give secondary foamability. A method in which foamed resin particles with foaming properties are filled into a mold, steam heated, and molded.
Further, there is a method of combining two or more of the above (1) to (3).
[0040]
Next, when the colored thermoplastic resin foam particles are filled into the mold, the bulk volume of the colored thermoplastic resin foam particles is compressed within the range of 50 to 99% by the above mold, and the apparent density is reduced. With and without
Subsequently, it is preferable to perform the said heating. (Claims6)
[0041]
Thereby, at the time of thermoforming, the amount of gaps between the foamed resin particles and the density of the foamed molded product can be adjusted, and a colored foamed molded product having desired physical properties can be obtained.
When the foamed resin particles in the mold before heating are compressed to a state where the bulk volume of the foamed resin particles is smaller than 50%, a foamed molded product having almost no gap can be obtained.
On the other hand, if it is higher than 99%, the contact area between the foamed resin particles becomes small, which may result in a foamed molded article with low fusion strength. More preferably, the bulk volume of the thermoplastic resin expanded particles is 50 to 80%.
[0042]
The foamed molded product obtained as described above is used for colored heat insulating materials, cushioning materials, packaging containers and the like.
[0043]
【Example】
Next, the Example which manufactures the colored thermoplastic resin expanded particle and a foaming molding is shown.
Example 1
Polypropylene expanded particles “EP Pole EA480” manufactured by Mitsubishi Chemical Foam Plastic Co., Ltd. (SP value of 18.8 for polypropylene, softening temperature 131 ° C., density 0.9 g / cm) as thermoplastic resin expanded particlesThree, 50% particle diameter of foamed particles 2.7 mm, L / d = 2) 50 g, 0.15 g (0.3 parts by weight) “Oil Blue 630” (Solvent Blue 36, anthraquinone series) manufactured by Orient Chemical Industries as a blue dye ), 0.005 g (0.01 part by weight) of N, N-bis (hydroxyethyl) alkylamine as an antistatic agent was placed in an autoclave equipped with a stirrer having an internal volume of about 3 L and mixed with stirring 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, followed by cooling to obtain blue thermoplastic resin foam particles.
Next, the colored thermoplastic resin foam particles are compressed and filled (bulk density 60 kg / m) so that the volume of the foam resin particles is reduced by about 30% in the mold of a molding machine for expanded polypropylene (EPV-600 manufactured by Daisen Kogyo Co., Ltd.).ThreeThen, the mixture was heated at a water vapor pressure of 0.35 MPa, heated and fused, and then cooled, and the foamed molded product was taken out from 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]
(Reference example 1)
In this example, a thermoplastic resin foam particle colored 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 series) manufactured by Orient Chemical Industries was used.
[0046]
(Example 3)
In this example, a thermoplastic resin foam particle colored in the same manner as in Example 1 except that the blue dye of Example 1 is carbon black and the impregnating agent is 0.5 g (1 part by weight) of cyclohexane is prepared. The foamed thermoplastic resin foamed particles were molded to obtain a foamed molded product. As carbon black, 0.005 g (0.01 parts by weight) of “Carbon Black Reagent” manufactured by Nacalai Co., Ltd. was used.
[0047]
Example 4
In this example, the thermoplastic resin colored in the same manner as in Example 1 except that the blue dye of Example 1 was carbon black, the impregnation temperature was changed to 120 ° C., and the impregnation agent was 0.5 g (1 part by weight) of cyclohexane. Foamed particles were prepared, and the colored thermoplastic resin foamed particles were molded to obtain a foamed molded product. As carbon black, 0.005 g (0.01 parts by weight) of “Carbon Black Reagent” manufactured by Nacalai 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 is graphite, the impregnation temperature is changed to 120 ° C., and the impregnating agent is 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 graphite, 0.005 g (0.01 part by weight) of “Graphite Reagent” manufactured by Nacalai Co., Ltd. was used.
[0049]
(Reference example 2)
In this example, the colored thermoplastic resin foam particles were prepared in the same manner as in Example 1 except that the impregnating agent was not added, and the colored thermoplastic resin foam particles were molded to obtain a foam molded article.
[0050]
(Reference example 3)
In this example, the colored thermoplastic resin foamed particles were prepared in the same manner as in Example 1 except that the impregnation temperature in Example 1 was changed to 120 ° C. and no impregnating agent was added. Molded to obtain a foamed molded product.
[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 Pole EA190” (polypropylene SP value 18.8, manufactured by Mitsubishi Chemical Foam Plastic Co., Ltd.). Softening temperature 131 ° C, density 0.9g / cmThree, 50% average particle size of foamed particles 3.3 mm, L / d = 1.2) 20 g, liquid paraffin (Molesco White P60 manufactured by Matsumura Oil Research Co., Ltd.) 3 g (15 parts by weight) as the impregnating agent Colored thermoplastic resin foam particles were prepared in the same manner as in Example 1 except that the inhibitor was not added.
[0052]
The colored thermoplastic resin foam particles thus obtained were compressed and filled (bulk density 30 kg / m) on a foamed polypropylene molding machine (EPV-600 manufactured by Daisen Kogyo Co., Ltd.) so as to reduce the volume of the foamed resin particles by about 50%.ThreeThen, heat fusion was performed at a water vapor pressure of 0.25 MPa, and after cooling, the foamed molded product was taken out of the mold, and a molded product having a length of 120 mm, a width of 300 mm, and a thickness of 40 mm was obtained.
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 expanded thermoplastic resin particles of Example 1 are made of “Styropol JQ250NX” (polystyrene SP value 18.6, softening temperature 111 ° C., density 1.05 g / cm, manufactured by Mitsubishi Chemical Foam Plastic Co., Ltd.).Three, 20 g of polystyrene foam particles obtained by foaming 50% particle diameter of 3.1 mm, L / d = 1) to a bulk density of 20 g / l using a 30 L batch type foaming machine, and 0.6 g (3 parts by weight) of an impregnating agent. 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, colored thermoplastic resin foamed particles were prepared.
[0054]
The colored thermoplastic resin foam particles thus obtained were heat-sealed at a water vapor pressure of 0.07 MPa with a foaming polystyrene molding machine (Daisen Kogyo Co., Ltd .: VS-500) to obtain a foamed molded product of 300 mm × 75 mm × 25 mm. .
As an orange dye, “OPLAS ORANGE 230” (Solvent Orange 60, perinone series) manufactured by Orient Chemical Industries was used.
[0055]
Next, the first embodiment described above., 3-5, 8,9And Reference Examples 1, 2, 3The colored thermoplastic resin foam particles and foamed molded product obtained in 1 above were evaluated for color unevenness and the impregnation state of the colorant by the following methods. In addition, the above embodiment,In the reference exampleThe degree of color contamination of the molding machine was evaluated.
[0056]
(Color unevenness)
The colored thermoplastic resin foamed particles and the molded product were visually evaluated for color unevenness (where there is a difference in shading).
The above thermoplastic resin expanded particles and the molded product have substantially no difference in density, and when they appear to be uniform, ○, a slight difference in density is observed, but there is little color unevenness, and a difference in density is clearly recognized, but color unevenness The case where there was little is evaluated as x.
The results are shown in Table 1.
[0057]
(Impregnated state)
The colored thermoplastic resin foam particles and the molded product were pressed against a white paper with a finger, and the transferability of the dye 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 the white paper was evaluated as △, and the case where coloring was clearly observed on the white paper was evaluated as x. The results are shown in Table 1.
[0058]
(Degree of contamination of molding machine)
The case where no dye residue was observed on the mold was evaluated as ◯, the case where some dye residue was observed was evaluated as Δ, and the case where dye residue was clearly observed was evaluated as ×. The results are shown in Table 1.
[0059]
[Table 1]
Example 1 as known from Table 1, 3-5, 8,The colored thermoplastic resin foam particles obtained by the production method 9 had little color unevenness and good dye impregnation properties. In addition, the foamed molded product obtained by molding the colored thermoplastic resin foamed particles had little color unevenness and good dye impregnation.
Example 1, 3-5, 8, 9In the method for producing colored thermoplastic resin expanded particles, the apparatus is not colored and contaminated with the colorant, and it is not necessary to use a particularly large apparatus.
[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 the impregnating agent was not added, and the others were produced in the same manner as in Example 1 to produce colored thermoplastic resin expanded particles. Molded to obtain a foamed molded product.
[0062]
(Comparative Example 2)
In this example, “EP Pole EA480” manufactured by Mitsubishi Chemical Foam Plastic Co., Ltd. (SP value of 18.8 of polypropylene, softening temperature of 131 ° C., density of 0.9 g / cm is used as the thermoplastic resin expanded particles.Three, 50 g of the foamed particle diameter 2.7 mm, L / d = 2) 50 g of toluene, 0.05 g (0.1 part by weight) of toluene as an impregnating agent, and “Oil” manufactured by Orient Chemical Industries as a blue dye Blue 630 "(Solvent Blue 36, anthraquinone type) 0.15 g (0.3 parts by weight) was prepared.
These are placed in an autoclave equipped with a stirrer with an internal volume of about 3 L, 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 foam particles were molded to obtain a foam molded article.
[0063]
Next, the first embodiment described above., 3-5, 8, 9By the same method as the colored thermoplastic resin expanded particles, the above Comparative Examples 1 to2The colored unevenness of the colored thermoplastic resin foam particles produced in the above and the impregnation state of the colorant were evaluated. In addition, the above implementationExampleBy the same method as that for the foamed molded product, the color unevenness and the colorant impregnation state of the foamed molded products obtained in Comparative Examples 1 and 2 were evaluated. The results are shown in Table 2.
[0064]
[Table 2]
As is known from Table 2, the colored thermoplastic resin foam particles and molded bodies obtained in Comparative Examples 1 and 2 were poor in colorant impregnation and caused color unevenness. Moreover, in the manufacturing method of the colored thermoplastic resin foaming molding of Comparative Examples 1-2, the metal mold | die 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 (6)
上記熱可塑性樹脂の軟化温度−８０℃〜軟化温度の範囲で加熱することによって，
発泡粒子に着色剤を含浸させる着色した熱可塑性樹脂発泡粒子の製造方法であって，
上記発泡粒子にあらかじめ着色剤を被覆または混合した後，
ＳＰ値が上記熱可塑性樹脂のＳＰ値±１０ＭＰａ 1/2 の範囲の含浸剤を混合した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。 And the foamed particles of the heat-friendly plastic resin and a colorant, under an anhydrous atmosphere,
By heating in the range of the softening temperature of the thermoplastic resin from −80 ° C. to the softening temperature ,
A method for producing colored thermoplastic resin foam particles in which foam particles are impregnated with a colorant,
After coating or mixing the above expanded particles with a colorant in advance,
A method for producing colored thermoplastic resin expanded particles, wherein an impregnating agent having an SP value in the range of SP value ± 10 MPa 1/2 of the thermoplastic resin is mixed .
上記着色した熱可塑性樹脂発泡粒子は，上記請求項１〜４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。 In a method for producing a molded body by heating and fusing the thermoplastic resin foam particles by filling the mold with colored thermoplastic resin foam particles and heating,
The colored thermoplastic resin foamed molded article , wherein the colored thermoplastic resin foamed particles are colored thermoplastic resin foamed particles obtained by the method according to any one of claims 1 to 4 . 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 5, when the colored thermoplastic resin foam particles are filled in the mold, the bulk volume of the colored thermoplastic resin foam particles is compressed within a range of 50 to 99% by the mold, No apparent density and no state,
Subsequently, the said heating is performed , The manufacturing method of the colored thermoplastic resin foaming molded object characterized by the above-mentioned .
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