JP4030340B2

JP4030340B2 - Method for producing colored styrene-based expandable resin particles

Info

Publication number: JP4030340B2
Application number: JP2002112410A
Authority: JP
Inventors: 昌臣島
Original assignee: JSP Corp
Current assignee: JSP Corp
Priority date: 2002-04-15
Filing date: 2002-04-15
Publication date: 2008-01-09
Anticipated expiration: 2022-04-15
Also published as: JP2003306572A

Description

【０００１】
【技術分野】
本発明はスチレン系発泡性樹脂粒子に染料を含浸させた着色スチレン系発泡性樹脂粒子の製造方法に関する。
【０００２】
【従来技術】
従来より，スチレン系発泡性樹脂粒子を発泡成形したスチレン系発泡体は，断熱材，包装緩衝材等に用いられている。
上記スチレン系発泡体は，スチレン系発泡性樹脂粒子をスチームで予備発泡させ，ついで，この予備発泡粒子をスチーム孔を有する型内に充填し，スチームにより加熱して二次発泡させて成形する。通常，染料を添加していない上記スチレン系発泡体は白色であるが，商品の差別化等を目的として，上記スチレン系発泡体を着色することが行われている。例えば，魚用クーラーとしては青色に，アメリカン冷凍ステーキ用容器としては茶色に着色されたスチレン系発泡体が使用されている。
【０００３】
従来，樹脂粒子に染料としての着色剤を含有させる方法としては，主として次の３つの方法が知られている。
（１）樹脂と着色剤とを押出機にて溶融混練し，ストランド状に押出し，これをペレット化する方法。
（２）発泡性樹脂粒子と着色剤とをブレンダーにて混合し，表面に着色剤を付着させる方法。
（３）発泡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行う方法。
【０００４】
しかし，上記（１）の方法では着色した樹脂ペレットを製造する際，色変更の度に押出機を清掃する必要があり，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（２）の方法は，比較的容易に着色剤を含有させることができるが，色落ちにより成形設備が汚染したり，また，発泡性樹脂粒子の表面に均一に着色剤を付着することができずに色ムラが発生し易い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全て吸収されずに水中に残存する。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大量に用いるため，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の方法としてスチレン系樹脂粒子と染料とを，ブタン，ペンタン，ネオペンタン等の発泡剤とともに分散させ，着色したスチレン系樹脂粒子を製造する方法が提案されている（特開昭５９−５６４３３号，特開平８−３１９３６６号）。この方法によれば，水を用いないため，大型の設備を用いる必要がなく，また，成形設備を汚染させることなくスチレン系樹脂粒子を着色することができる。
【０００６】
【解決しようとする課題】
しかしながら，上記第４の方法においては，スチレン系発泡性樹脂粒子に染料を含浸させる際に，スチレン系発泡性樹脂粒子が帯電する。そのため，上記スチレン系発泡性樹脂粒子の着色に色ムラが発生するという問題があった。
【０００７】
また，特開昭５９−５６４３３号の方法では染料の含浸性が不充分であるという問題があった。そのため，着色させたスチレン系発泡性樹脂粒子を発泡成形すると，該スチレン系発泡性樹脂粒子の表面に残存した染料が，スチレン系発泡性樹脂粒子同士の融着を妨げるという問題があった。それ故，上記スチレン系発泡性樹脂粒子を発泡成形して作製したスチレン系発泡体の強度が低下するという問題があった。
【０００８】
一方，特開平８−３１９３６６号の方法においては，トルエン，キシレン，ベンゼン等の芳香族炭化水素を用いることにより，染料の含浸性を向上させている。しかし，着色させたスチレン系発泡性樹脂粒子が凝結し易いという問題があった。
【０００９】
本発明は，かかる従来の問題点に鑑みてなされたもので，スチレン系発泡性樹脂粒子に染料を色ムラ発生なく含浸させることができ，かつ染料含浸時に凝結しにくく，発泡成形時の融着性に優れた着色スチレン系発泡性樹脂粒子の製造方法を提供しようとするものである。
【００１０】
【課題の解決手段】
本発明は，スチレン系発泡性樹脂粒子，染料及び発泡剤を，密閉容器内にて，スチレン系発泡性樹脂粒子の発泡温度よりも低い温度で加熱しながら攪拌し，スチレン系発泡性樹脂粒子に染料を含浸させて着色スチレン系発泡性樹脂粒子を製造する方法において，
上記染料の含浸にあたっては，上記密閉容器内の水分量が，上記スチレン系発泡性樹脂粒子１００重量部に対して０．００１〜２重量部で，かつ脂肪酸エステル類の存在下で行うことを特徴とする着色スチレン系発泡性樹脂粒子の製造方法にある（請求項１）。
【００１１】
本発明においては，染料含浸時における密閉容器内の水分量が，上記スチレン系発泡性樹脂粒子１００重量部に対して０．００１〜２重量部である。
そのため，上記スチレン系発泡性樹脂粒子の表面が帯電することを防止することができる。それ故，上記染料を色ムラなく含浸させることができる。また，上記密閉容器内の水分量は，上記スチレン系発泡性樹脂粒子１００重量部に対して０．００１〜２重量部という非常に少ない量である。そのため，上記の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はない。
【００１２】
また，本発明においては，脂肪酸エステル類の存在下で染料の含浸を行っている。
そのため，上記染料の含浸性が向上すると共に，上記着色スチレン系発泡性樹脂粒子が互いに凝結することを抑制することができる。また，染料を含浸させる際に，スチレン系発泡性樹脂粒子の表面に余分な染料が残留することを防止することができる。そのため，上記着色スチレン系発泡性樹脂粒子を発泡成形するときには，該着色スチレン系発泡性樹脂粒子が互いに強固に融着し易くなる。それ故，強度に優れたスチレン系発泡体を得ることができる。
【００１３】
このように，本発明によれば，スチレン系発泡性樹脂粒子に染料を色ムラ発生なく含浸させることができ，かつ染料含浸時に凝結しにくく，発泡成形時の融着性に優れた着色スチレン系発泡性樹脂粒子の製造方法を提供することができる。
【００１４】
【発明の実施の形態】
本発明（請求項１）においては，上記密閉容器中の水分量は，スチレン系発泡性樹脂粒子１００重量部に対して０．００１〜２重量部である。
上記水分量が０．００１重量部未満の場合には，上記染料をスチレン系発泡性樹脂粒子に含浸させる際に，上記スチレン系発泡性樹脂粒子が帯電し，着色スチレン系発泡性樹脂粒子に色ムラが発生する。一方，２重量部を超える場合には，上記着色スチレン系発泡性樹脂粒子が互いに凝結し易くなる。
【００１５】
また，上記スチレン系発泡性樹脂粒子，染料及び発泡剤は，密閉容器内にて，スチレン系発泡性樹脂粒子の発泡温度よりも低い温度，つまりスチレン系発泡性樹脂粒子が発泡しない温度で加熱する。上記発泡温度よりも高い温度で加熱すると，上記スチレン系発泡性樹脂粒子が発泡を開始してしまい，着色スチレン系発泡性樹脂粒子を作製することができない。ここで，上記発泡温度は，スチレン系発泡性樹脂粒子が発泡を開始する温度のことであり，一般的には，６０〜８０℃である。
【００１６】
また，上記脂肪酸エステル類としては，例えば２−エチルヘキサン酸ヘキサデシル，ヤシ脂肪酸メチル，ラウリン酸メチル，ミリスチン酸イソプロピル，パルミチン酸イソプロピル，パルミチン酸２−エチルヘキシル，牛脂脂肪酸メチル，ミリスチン酸オクチルドデシル，ステアリン酸メチル，ステアリン酸ブチル，ステアリン酸２−エチルヘキシル，ステアリン酸イソトリデシル，カプリン酸メチル，ミリスチン酸メチル，オレイン酸メチル，オレイン酸イソブチル，オレイン酸オクチル，オレイン酸ラウリル，オレイン酸オレイル，ミリスチン酸ミリスチル，ステアリン酸ステアリル，オレイン酸２−エチルヘキシル，オレイン酸デシル，オレイン酸イソブチル等の脂肪酸と１価のアルコールのエステル，ソルビタンモノラウレート，ソルビタンモノパルミテート，ソルビタンモノステアレート，ソルビタントリステアレート，ソルビタンモノオレエート，ソルビタントリオレエート，ポリエチレングリコールモノラウエート，ポリエチレングリコールモノステアレート，ポリエチレングリコールジステアレート，ペンタエリスリトールモノステアレート，グリセリンモノステアレート，グリセリンジステアレート，グリセリントリステアレート，グリセリンモノオレエート，硬化牛脂，硬化ヒマシ油等の脂肪酸と多価アルコールのエステル等がある。また，これらの脂肪酸エステル類は，単独で又は混合して使用することができる。好ましくはグリセリン脂肪酸エステルを用いるのがよい。
【００１７】
また，上記スチレン系発泡性樹脂粒子としては，発泡剤を含有するスチレン系樹脂粒子を用いることができる。
スチレン系発泡性樹脂粒子を製造する方法としては，例えば特開平７−７９３７６号及び特開平８−２５３５１０号に開示されている方法がある。即ち，まず重合開始剤及び懸濁剤の存在下にて，スチレン系単量体を水性媒体中に分散させる。その後，重合反応を開始し，該重合反応の前後または途中で発泡剤を添加し，スチレン系発泡性樹脂粒子を製造する方法である。
【００１８】
また，他の製造方法としては，押出機内にてスチレン系樹脂と揮発性発泡剤とを溶融混練し，押出機先端のダイの細孔より押出し，直ちに水中へ導入し急冷し，未発泡の状態で粒子化し，スチレン系発泡性樹脂粒子を製造する方法がある。
また，押出機中でスチレン系樹脂を溶融混練し，ストランドカット，ホットカット，水中カット等の方法により０．５〜５ｍｇ／個の大きさの粒子とし，得られたスチレン系樹脂の樹脂粒子を密閉容器中に，懸濁剤の存在下で水性媒体に分散させる。その後，揮発性発泡剤を樹脂粒子に含浸させて，スチレン系発泡性樹脂粒子を製造する方法がある（特開２０００−１７８３７３号）。
【００１９】
上記染料の含浸の際に用いる発泡剤としては，沸点が９０℃以下のプロパン，ノルマルブタン，イソブタン，ノルマルペンタン，イソペンタン，ネオペンタン，ヘキサン等の脂肪族炭化水素，又はシクロブタン，シクロペンタン等の脂環族炭化水素等がある。
沸点が９０℃を超える場合には，上記染料を含浸させる際に，スチレン系発泡性樹脂粒子が互いに凝結するおそれがある。さらに好ましくは，沸点が６０℃以下の脂肪族炭化水素や脂環族炭化水素である。また，これらの発泡剤は，単独で又は混合して使用することができる。また，上記染料含浸時に用いる発泡剤は，既にスチレン系発泡性樹脂粒子に含有されている発泡剤と同じものでも異なるものでも良い。
【００２０】
また，染料含浸時に用いる上記発泡剤の添加量は，スチレン系発泡性樹脂粒子１００重量部に対して１〜１０重量部であることが好ましい。
上記発泡剤の添加量が１重量部未満の場合には，スチレン系発泡性樹脂粒子に染料が完全に含浸されないおそれがある。一方，１０重量部を超える場合には，スチレン系発泡性樹脂粒子が互いに凝結するおそれがある。更に好ましくは２〜５重量部がよい。
【００２１】
また，上記染料としては，アゾ系染料，アントラキノン系染料，アジン系染料，キノリン系染料等がある。上記染料の量はスチレン系発泡性樹脂粒子１００重量部に対し，０．００１〜１重量部であることが好ましい。上記染料の量が０．００１重量部未満の場合には，上記スチレン系発泡性樹脂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，１重量部を超える場合には，スチレン系発泡性樹脂粒子に染料が充分に含浸されないおそれがある。
【００２２】
また，上記染料の粒子径は１００メッシュ篩を通過するものであることが好ましい。１００メッシュ篩を通過しない染料では，スチレン系発泡性樹脂粒子への含浸性が悪くなるおそれがある。
【００２３】
また，上記密閉容器は，密閉可能で，例えば容器内の攪拌，混合が可能，かつ加熱可能であるものを用いることが好ましい。このような密閉容器としては，例えば攪拌装置付きオートクレーブ及び密閉可能なミキサー等がある。
【００２４】
また，上記染料，脂肪酸エステル類，水及び発泡剤の投入順序に制約はない。しかし，上記発泡剤は，スチレン系発泡性樹脂粒子の表面部分に染料や脂肪酸エステル類が混合あるいは被覆された後に添加することが好ましい。この場合には，上記染料をスチレン系発泡性樹脂粒子に色ムラなく含浸させることができる。また，密閉容器内に投入する前に，上記染料，脂肪酸エステル類及び水はあらかじめスチレン系発泡性樹脂粒子に混合あるいは被覆されていてもよい。また，上記発泡剤は，加熱前，加熱中，または所定温度到達後のいずれの状態で添加しても良いし，複数回に分けて添加しても良い。
【００２５】
次に，上記水分量は，上記スチレン系発泡性樹脂粒子１００重量部に対して０．００５〜１重量部であることが好ましい（請求項２）。
この場合には，上記スチレン系発泡性樹脂粒子にほぼ均一な着色を施すことができる。さらに好ましくは，０．０１〜０．５重量部がよい。
【００２６】
次に，上記脂肪酸エステル類は，上記スチレン系発泡性樹脂粒子１００重量部に対して０．００１〜１重量部であることが好ましい（請求項３）
０．００１重量部未満の場合には，上記スチレン系発泡性樹脂粒子に染料を充分に含浸させる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，上記着色スチレン系発泡性樹脂粒子の表面の可塑化が大きくなりすぎて，凝結が発生するおそれがある。さらに好ましくは，０．０１〜０．５重量部がよい。
【００２７】
次に，上記脂肪酸エステル類の融点は７０℃以下であることが好ましい（請求項４）。
上記脂肪酸エステル類の融点が７０℃を超える場合には，上記スチレン系発泡性樹脂粒子に染料を充分に含浸させることができなくなるおそれがある。
【００２８】
次に，上記密閉容器内の加熱の温度は，２０〜８０℃であることが好ましい（請求項５）。
上記加熱の温度が８０℃を超える場合には，上記スチレン系発泡性樹脂粒子が発泡を開始するおそれがあり，所望の着色スチレン系発泡性樹脂粒子を得ることができないおそれがある。一方，２０℃未満の場合には，上記スチレン系発泡性樹脂粒子に染料が充分に含浸されないおそれがある。
【００２９】
また，上記染料を上記スチレン系発泡性樹脂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，上記スチレン系発泡性樹脂粒子に染料が充分に含浸されないおそれがある。
なお，染料の含浸時間を短縮させるためには，上記加熱の温度をできるだけ高くすると良い。
【００３０】
【実施例】
次に，着色スチレン系発泡性樹脂粒子を製造する実施例を示す。
本例の着色スチレン系発泡性樹脂粒子の製造方法は，スチレン系発泡性樹脂粒子，染料及び発泡剤を，密閉容器内にて，スチレン系発泡性樹脂粒子の発泡温度よりも低い温度で加熱しながら攪拌し，スチレン系発泡性樹脂粒子に染料を含浸させて着色スチレン系発泡性樹脂粒子を製造する方法である。また，上記染料の含浸にあたっては，上記密閉容器内の水分量が，上記スチレン系発泡性樹脂粒子１００重量部に対して０．００１〜２重量部で，かつ脂肪酸エステル類の存在下で行う。
【００３１】
以下，上記着色スチレン系発泡性樹脂粒子の製造方法につき詳細に説明する。
まず，以下の方法により，３種類のスチレン系発泡性樹脂粒子Ａ〜Ｃを準備した。
（スチレン系発泡性樹脂粒子Ａ）
撹拌機付きの５０リットルのオートクレーブに，イオン交換水１８リットルと，難水溶性の無機系懸濁剤としての第３リン酸カルシウム（太平化学産業株式会社製）６３ｇと，界面活性剤としてのドデシルベンゼンスルホン酸ナトリウム(東京化成工業株式会社製)０．５４ｇとを投入した。
【００３２】
次いで，撹拌下に重合開始剤としてのベンゾイルパーオキサイド（日本油脂株式会社製，純度７５％）４５ｇ（純品換算で３３．７５ｇ）とｔ−ブチルパーオキシ２−エチルヘキシルカーボネート２７ｇと，有機臭素化合物としての１，２，５，６，９，１０−ヘキサブロモシクロドデカン１０８ｇと，可塑剤として硬化牛脂１８０ｇを溶解させたスチレンモノマー１８ｋｇとを投入した。
【００３３】
次に，撹拌下で３０分間室温のまま放置した後，１時間半かけて９０℃まで昇温し，更に６時間半かけて１００℃まで昇温した。この間，９０℃到達後から５時間後に，ブタン１．７ｋｇをオートクレーブに圧入した。その後さらに，１１０℃まで３時間かけて昇温し，そのまま攪拌下にて１１０℃を５時間保持した。続いて，４時間かけて３０℃まで冷却し，スチレン系発泡性樹脂粒子を作製した。
【００３４】
さらに，上記スチレン系発泡性樹脂粒子を遠心分離機にて脱水し，流動乾燥装置で表面付着水分を除去した。その後，目開きが０．７ｍｍと１．４ｍｍの篩いで篩い分け，粒子径が０．７〜１．４ｍｍのスチレン系発泡性樹脂粒子Ａを得た。
【００３５】
（スチレン系発泡性樹脂粒子Ｂ）
撹拌機付きの５０リットルのオートクレーブに，イオン交換水２０リットルと，難水溶性の無機系懸濁剤としての第３リン酸カルシウム（太平化学産業株式会社製）８０ｇと，界面活性剤としてのドデシルベンゼンスルホン酸ナトリウム(東京化成工業株式会社製)０．８ｇとを投入した。
次いで，撹拌下に，重合開始剤としてのｔ−ブチルパーオキシ２−エチルヘキサノエート４５ｇとｔ−ブチルパーオキシ２−エチルヘキシルカーボネート２７ｇと，可塑剤としてシクロヘキサン２７０ｇと硬化牛脂１３５ｇを溶解させたスチレンモノマー１８ｋｇとを投入した。
【００３６】
次に，撹拌下で３０分間室温のまま放置した後，１時間半かけて９０℃まで昇温し，更に５時間半かけて１００℃まで昇温した。この間，９０℃到達後から４時間後にブタン１．７ｋｇをオートクレーブに圧入した。その後さらに，１００℃から１１０℃まで１時間半かけて昇温し，そのまま攪拌下にて１１０℃を２時間保持した。続いて，４時間かけて３０℃まで冷却し，スチレン系発泡性樹脂粒子を作製した。
【００３７】
さらに，上記スチレン系発泡性樹脂粒子を遠心分離機にて脱水し，流動乾燥装置で表面付着水分を除去した。その後，目開きが０．７ｍｍと１．４ｍｍの篩いで篩い分け，粒子径が０．７〜１．４ｍｍのスチレン系発泡性樹脂粒子Ｂを得た。
【００３８】
（スチレン系発泡性樹脂粒子Ｃ）
撹拌機付きの５０リットルのオートクレーブに，イオン交換水１８リットルと，難水溶性の無機系懸濁剤としての第３リン酸カルシウム（太平化学産業株式会社製）６３ｇと，界面活性剤としてのドデシルベンゼンスルホン酸ナトリウム(東京化成工業株式会社製)０．５４ｇとを投入した。
次いで，撹拌下に，重合開始剤としてのｔ−ブチルパーオキシ２−エチルヘキサノエートを４５ｇとｔ−ブチルパーオキシ２−エチルヘキシルカーボネート２７ｇと，可塑剤としてフタル酸−ジ−２−エチルヘキシル１８０ｇを溶解させたスチレンモノマー１８ｋｇとを投入した。
【００３９】
次に，撹拌下で３０分間室温のまま放置した後，１時間半かけて９０℃まで昇温し，更に５時間かけて１１０℃まで昇温した。この間，９０℃到達後から３時間半後にブタン１．７ｋｇをオートクレーブに圧入した。その後さらに，そのまま攪拌下にて１１０℃を４時間保持した。続いて，４時間かけて３０℃まで冷却し，スチレン系発泡性樹脂粒子を作製した。
【００４０】
さらに，上記スチレン系発泡性樹脂粒子を遠心分離機にて脱水し，流動乾燥装置で表面付着水分を除去した。その後，目開きが０．７ｍｍと１．４ｍｍの篩いで篩い分け，粒子径が０．７〜１．４ｍｍのスチレン系発泡性樹脂粒子Ｃを得た。
【００４１】
次に，以下のようにして，上記スチレン系発泡性樹脂粒子Ａ〜Ｃを着色し，発泡成形した。
（実施例１）
上記スチレン系発泡性樹脂粒子としてのスチレン系発泡性樹脂粒子Ａ５００ｇと，青色染料としてのオリエント化学工業製「ＯｉｌＢｌｕｅ６３０」（ＳｏｌｖｅｎｔＢｌｕｅ３６）１．０ｇと，脂肪酸エステル類としてのグリセリントリステアレート（融点６５−６９℃）０．５ｇと，水０．５ｇとを，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。
【００４２】
次いで，３０分かけて７０℃まで昇温し，発泡剤としてブタン（ノルマルブタン約７０％，イソブタン約３０％の混合物）１５ｇを上記オートクレーブ内に添加した。添加後，更に７０℃にて３時間撹拌を続け，その後冷却して，青色の着色スチレン系発泡性樹脂粒子を得た。
【００４３】
次に，上記着色スチレン系発泡性樹脂粒子を３０Ｌのバッチ式発泡機により，嵩密度３３ｇ／ｌに発泡させ，予備発泡粒子を得た。続いて，得られた予備発泡粒子を１日間室温で放置（熟成）し，２５×７５×３００ｍｍの金型内に充填し０．０７ＭＰａの蒸気吹き込み圧で２０秒間加熱成形し，スチレン系発泡体を得た。
【００４４】
（実施例２）
本例では，実施例１の水の添加量を０．０１ｇに変え，他は実施例１と同様にして着色スチレン系発泡性樹脂粒子を作製し，該着色スチレン系発泡性樹脂粒子を発泡成形して発泡成形体を得た。
【００４５】
（実施例３）
本例では，実施例１の水の添加量を０．０４ｇに変え，他は実施例１と同様にして着色スチレン系発泡性樹脂粒子を作製し，該着色スチレン系発泡性樹脂粒子を発泡成形して発泡成形体を得た。
【００４６】
（実施例４）
本例では，実施例１の水の添加量を４．０ｇに変え，他は実施例１と同様にして着色スチレン系発泡性樹脂粒子を作製し，該着色発泡性樹脂粒子を発泡成形して発泡成形を得た。
【００４７】
（実施例５）
本例では，実施例１の水の添加量を７．５ｇに変え，他は実施例１と同様にして着色スチレン系発泡性樹脂粒子を作製し，該着色発泡性樹脂粒子を発泡成形して発泡成形体を得た。
【００４８】
（実施例６）
本例では，実施例１のグリセリントリステアレートの添加量を２．５ｇに変え，他は実施例１と同様にして着色スチレン系発泡性樹脂粒子を作製し，該着色発泡性樹脂粒子を発泡成形して発泡成形体を得た。
【００４９】
（実施例７）
本例では，実施例１のグリセリントリステアレートの添加量を７．５ｇに変え，他は実施例１と同様にして着色スチレン系発泡性樹脂粒子を作製し，該着色発泡性樹脂粒子を発泡成形して発泡成形体を得た。
【００５０】
（実施例８）
本例では，実施例１のグリセリントリステアレート（融点６５−６９℃）をグリセリンジステアレート（融点６１℃）に変え，他は実施例１と同様にして着色スチレン系発泡性樹脂粒子を作製し，該着色発泡性樹脂粒子を発泡成形して発泡成形体を得た。
【００５１】
（実施例９）
本例では，実施例１のグリセリントリステアレート（融点６５−６９℃）をグリセリントリ２−エチルヘキシレート（融点−３０℃）に変え，他は実施例１と同様にして着色スチレン系発泡性樹脂粒子を作製し，該着色発泡性樹脂粒子を発泡成形して発泡成形体を得た。
【００５２】
（実施例１０）
本例では，実施例１のグリセリントリステアレート（融点６５−６９℃）をソルビタンモノオレエート（融点９℃）に変え，他は実施例１と同様にして着色スチレン系発泡性樹脂粒子を作製し，該着色発泡性樹脂粒子を発泡成形して発泡成形体を得た。
【００５３】
（実施例１１）
本例では，実施例１のグリセリントリステアレート（融点６５−６９℃）を硬化ヒマシ油（融点８４℃）に変え，他は実施例１と同様にして着色スチレン系発泡性樹脂粒子を作製し，該着色発泡性樹脂粒子を発泡成形して発泡成形体を得た。
【００５４】
（実施例１２）
本例では，実施例１のブタンの添加量を５ｇに変え，他は実施例１と同様にして着色スチレン系発泡性樹脂粒子を作製し，該着色発泡性樹脂粒子を発泡成形して発泡成形体を得た。
【００５５】
（実施例１３）
本例では，実施例１のブタンの添加量を３５ｇに変え，他は実施例１と同様にして着色スチレン系発泡性樹脂粒子を作製し，該着色発泡性樹脂粒子を発泡成形して発泡成形体を得た。
【００５６】
（実施例１４）
本例では，実施例１のブタン（ノルマルブタン約７０％，イソブタン約３０％の混合物）１５ｇを，ペンタン（ノルマルペンタン約８０％，イソペンタン約２０％の混合物）７．５ｇとブタン（ノルマルブタン約７０％，イソブタン約３０％の混合物）７．５ｇの混合物に変え，他は実施例１と同様にして着色スチレン系発泡性樹脂粒子を作製し，該着色発泡性樹脂粒子を発泡成形して発泡成形体を得た。
【００５７】
（実施例１５）
本例では，実施例１のブタン（ノルマルブタン約７０％，イソブタン約３０％の混合物）をペンタン（ノルマルペンタン約８０％，イソペンタン約２０％の混合物）に変え，他は実施例１と同様にして着色スチレン系発泡性樹脂粒子を作製し，該着色発泡性樹脂粒子を発泡成形して発泡成形体を得た。
【００５８】
（実施例１６）
本例では，実施例１の青色染料を赤色染料に変え，他は実施例１と同様にして，赤色染料を含浸させた着色スチレン系発泡性樹脂粒子を作製し，該着色発泡性樹脂粒子を発泡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「ＯＰＬＡＳＲＥＤ３３０」（ＳｏｌｖｅｎｔＲｅｄ１１１）１．０ｇを用いた。
【００５９】
（実施例１７）
本例では，実施例１の青色染料を黄色染料に変え，他は実施例１と同様にして，黄色顔料を含浸させた着色スチレン系発泡性樹脂粒子を作製し，該着色発泡性樹脂粒子を発泡成形して発泡成形体を得た。なお，黄色染料としては，オリエント化学工業製「ＯＰＬＡＳＹＥＬＬＯＷ１３６」（ＳｏｌｖｅｎｔＹｅｌｌｏｗ３３）１．０ｇを用いた。
【００６０】
（実施例１８）
本例では，実施例１のスチレン系発泡性樹脂粒子Ａをスチレン系発泡性樹脂粒子Ｂに変え，他は実施例１と同様にして着色スチレン系発泡性樹脂粒子を作製し，該着色発泡性樹脂粒子を発泡成形して発泡成形体を得た。
【００６１】
（実施例１９）
本例では，実施例１のスチレン系発泡性樹脂粒子Ａをスチレン系発泡性樹脂粒子Ｃに変え，他は実施例１と同様にして着色スチレン系発泡性樹脂粒子を作製し，該着色発泡性樹脂粒子を発泡成形して発泡成形体を得た。
【００６２】
次に，上記実施例１〜１９にて得られた着色スチレン系発泡性樹脂粒子につき，帯電状態，染料の含浸状態，凝結量を下記の方法によって評価した。また，上記実施例１〜１９にて得られた発泡成形体の融着度合いについて評価した。
【００６３】
（帯電状態）
上記着色スチレン系発泡性樹脂粒子の作製後に，上記オートクレーブの内壁に付着した着色スチレン系発泡性樹脂粒子の数を計測した。オートクレーブの内壁に付着した着色スチレン系発泡性樹脂粒子数が全着色スチレン系発泡性樹脂粒子数の１／２０未満の場合を◎とし，１／２０以上から１／１０未満の場合を○とし，１／１０以上ｎ場合を×として評価した。その結果を表１に示す。
【００６４】
（含浸状態）
上記着色スチレン系発泡性樹脂粒子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，白色上に着色がほとんど観察されない場合を○とし，白色紙上に着色がはっきりと観察された場合を×として評価した。その結果を表１に示す。
【００６５】
（凝結量）
上記着色スチレン系発泡性樹脂粒子を目開き１．７mmのＪＩＳ篩でふるい，篩上に残留した着色スチレン系発泡性樹脂粒子の数を，篩いにかけた全スチレン系発泡性樹脂粒子の数で除算し，凝結量として算定した。その結果を表１に示す。
【００６６】
（融着度）
上記発泡成形体を切断し，その断面において上記予備発泡粒子の界面に生じた裂けを目視にて観察した。上記予備発泡粒子のすべての界面で裂けが発生している場合を０とし，上記予備発泡粒子の界面で裂けが全く発生していない場合を１として評価した。なお，評価は０から１の０．１毎の１０段階にて行った。その結果を表１に示す。
【００６７】
【表１】

【００６８】
表１より知られるごとく，本例（実施例１〜１９）の製造方法により得られた着色スチレン系発泡性樹脂粒子は，帯電が少なく，染料の含浸性が良好で，かつ凝結も非常に少なかった。また，上記着色スチレン系発泡性樹脂粒子を発泡成形した発泡成形体は，融着が強固であった。
また，実施例１〜１９の着色スチレン系発泡性樹脂粒子の製造方法においては，装置を染料で汚染することはなく，また特別に大きな装置を用いる必要もない。
【００６９】
このように，本例によれば，スチレン系発泡性樹脂粒子に染料を色ムラ発生なく含浸させることができ，かつ染料含浸時に凝結しにくく，発泡成形時の融着性に優れた着色スチレン系発泡性樹脂粒子の製造方法を提供することができる。
【００７０】
次に，比較のために以下に示す比較例１〜６を行った。
（比較例１）
本例では，水を添加せずに，他は実施例１と同様にして着色スチレン系発泡性樹脂粒子を作製し，該着色発泡性樹脂粒子を発泡成形して発泡成形体を得た。
【００７１】
（比較例２）
本例では，実施例１の水の添加量を１５ｇに変え，他は実施例１と同様にして着色スチレン系発泡性樹脂粒子を作製し，該着色発泡性樹脂粒子を発泡成形して発泡成形体を得た。
【００７２】
（比較例３）
本例では，実施例１の脂肪酸エステル類を添加せずに，他は実施例１と同様にして着色スチレン系発泡性樹脂粒子を作製し，該着色発泡性樹脂粒子を発泡成形して発泡成形体を得た。
【００７３】
（比較例４）
本例では，実施例１の発泡剤を添加せずに，他は実施例１と同様にして着色スチレン系発泡性樹脂粒子を作製し，該着色発泡性樹脂粒子を発泡成形して発泡成形体を得た。
【００７４】
（比較例５）
本例では，実施例１の脂肪酸エステル類及び発泡剤を添加せずに，他は実施例１と同様にして着色スチレン系発泡性樹脂粒子を作製し，該着色発泡性樹脂粒子を発泡成形して発泡成形体を得た。
【００７５】
（比較例６）
本例では，実施例１の脂肪酸エステル類の代わりにトルエン０．５ｇを用いて，他は実施例１と同様にして着色スチレン系発泡性樹脂粒子を作製し，該着色発泡性樹脂粒子を発泡成形して発泡成形体を得た。
【００７６】
次に，上記実施例１〜１９の着色スチレン系発泡性樹脂粒子と同様の方法により，上記比較例１〜６にて作製した着色スチレン系発泡性樹脂粒子の帯電状態，染料の含浸状態，及び凝結量を評価した。また，上記実施例１〜１９の発泡成形体と同様の方法により，上記比較例１〜６にて得られた発泡成形体の融着度を評価した。その結果を表２に示す。
【００７７】
【表２】

【００７８】
表２より知られるごとく，比較例１及び６にて得られる着色スチレン系発泡性樹脂粒子は，帯電が大きく，色ムラが発生していた。また，比較例２及び比較例６においては，着色スチレン系発泡性樹脂粒子同士の凝結が発生していた。また，比較例３〜５においては，染料の含浸性が不良であった。さらに，比較例３〜６において得られる発泡成形体は，融着が弱く，強度に問題があった。[0001]
【Technical field】
The present invention relates to a method for producing colored styrene-based expandable resin particles obtained by impregnating a styrene-based expandable resin particle with a dye.
[0002]
[Prior art]
Conventionally, styrene foams obtained by foam-molding styrene foam resin particles have been used as heat insulating materials, packaging cushioning materials, and the like.
The styrenic foam is molded by pre-foaming styrenic foam resin particles with steam, and then filling the pre-foamed particles into a mold having steam holes, followed by secondary foaming by heating with steam. Usually, the styrenic foam to which no dye is added is white, but the styrenic foam is colored for the purpose of product differentiation. For example, styrene foam colored in blue for fish coolers and brown in American frozen steak containers is used.
[0003]
Conventionally, the following three methods are mainly known as methods for incorporating a colorant as a dye into resin particles.
(1) A method in which a resin and a colorant are melt-kneaded with an extruder, extruded into a strand, and pelletized.
(2) A method in which expandable resin particles and a colorant are mixed with a blender and the colorant is adhered to the surface.
(3) A method of suspending expandable resin particles in water and adding a dye and a coloring aid to the liquid.
[0004]
However, in the method (1), when producing colored resin pellets, it is necessary to clean the extruder every time the color is changed, and there is a problem that inventory management of resin pellets of each color becomes complicated. .
In the method (2), a colorant can be contained relatively easily. However, the molding equipment is contaminated by discoloration, and the colorant is uniformly attached to the surface of the expandable resin particles. There is a problem that color unevenness is likely to occur.
In the method (3), the dye suspended in water remains in water without being absorbed in the particles. 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 above problems (1) to (3), as a fourth method, styrene resin particles and a dye are dispersed together with a foaming agent such as butane, pentane, or neopentane, and colored styrene resin particles are obtained. A manufacturing method has been proposed (Japanese Patent Laid-Open Nos. 59-56433 and 8-319366). According to this method, since water is not used, it is not necessary to use a large facility, and the styrene resin particles can be colored without contaminating the molding facility.
[0006]
[Problems to be solved]
However, in the fourth method, the styrenic expandable resin particles are charged when the styrenic expandable resin particles are impregnated with the dye. Therefore, there is a problem that color unevenness occurs in the coloring of the styrene-based expandable resin particles.
[0007]
Further, the method disclosed in JP-A-59-56433 has a problem that the impregnation property of the dye is insufficient. Therefore, when the colored styrene foam resin particles are subjected to foam molding, there is a problem that the dye remaining on the surface of the styrene foam resin particles prevents the fusion of the styrene foam resin particles. Therefore, there is a problem that the strength of the styrene foam produced by foam molding of the styrene foam resin particles is lowered.
[0008]
On the other hand, in the method of JP-A-8-319366, the impregnation property of the dye is improved by using aromatic hydrocarbons such as toluene, xylene and benzene. However, there is a problem that the colored styrene-based expandable resin particles are easy to condense.
[0009]
The present invention has been made in view of such a conventional problem, and allows the styrenic expandable resin particles to be impregnated with the dye without causing color unevenness, and is difficult to condense when impregnated with the dye. An object of the present invention is to provide a method for producing colored styrene-based expandable resin particles having excellent properties.
[0010]
[Means for solving problems]
The present invention stirs styrenic foamable resin particles, a dye and a foaming agent in a sealed container while heating them at a temperature lower than the foaming temperature of the styrenic foamable resin particles. Colored styrene foam impregnated with dye sex In a method for producing resin particles,
In the impregnation of the dye, the water content in the sealed container is 0.001 to 2 parts by weight with respect to 100 parts by weight of the styrene-based expandable resin particles and in the presence of fatty acid esters. (1).
[0011]
In the present invention, the amount of water in the sealed container when impregnated with the dye is 0.001 to 2 parts by weight with respect to 100 parts by weight of the styrene-based expandable resin particles.
Therefore, it is possible to prevent the surface of the styrenic expandable resin particles from being charged. Therefore, the dye can be impregnated without color unevenness. Further, the amount of water in the sealed container is a very small amount of 0.001 to 2 parts by weight with respect to 100 parts by weight of the styrenic expandable resin particles. Therefore, unlike the coloring method by suspension in water, it is not necessary to use a large sealed container in consideration of the volume of water, and the equipment does not increase in size.
[0012]
In the present invention, the dye is impregnated in the presence of fatty acid esters.
Therefore, the impregnation property of the dye can be improved, and the colored styrene-based expandable resin particles can be prevented from condensing with each other. Moreover, when impregnating a dye, it can prevent that excess dye remains on the surface of a styrene-type expandable resin particle. For this reason, when the colored styrene-based expandable resin particles are subjected to foam molding, the colored styrene-based expandable resin particles are easily bonded firmly to each other. Therefore, a styrenic foam excellent in strength can be obtained.
[0013]
As described above, according to the present invention, a colored styrene-based resin can be impregnated with styrenic expandable resin particles without causing color unevenness, is not easily condensed when impregnated with the dye, and has excellent fusion property during foam molding. A method for producing expandable resin particles can be provided.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
In the present invention (Claim 1), the water content in the sealed container is 0.001 to 2 parts by weight with respect to 100 parts by weight of the styrene-based expandable resin particles.
When the water content is less than 0.001 part by weight, when the styrenic expandable resin particles are impregnated with the dye, the styrenic expandable resin particles are charged, and the colored styrene expandable resin particles are colored. Unevenness occurs. On the other hand, when the amount exceeds 2 parts by weight, the colored styrene-based expandable resin particles tend to coagulate with each other.
[0015]
The styrenic foamable resin particles, dye and foaming agent are heated in a sealed container at a temperature lower than the foaming temperature of the styrenic foamable resin particles, that is, a temperature at which the styrenic foamable resin particles do not foam. . When heated at a temperature higher than the foaming temperature, the styrenic foamable resin particles start to foam, and colored styrene foam sex Resin particles cannot be produced. Here, the foaming temperature is a temperature at which the styrene-based expandable resin particles start to foam, and is generally 60 to 80 ° C.
[0016]
Examples of the fatty acid esters include hexadecyl 2-ethylhexanoate, methyl palm fatty acid, methyl laurate, isopropyl myristate, isopropyl palmitate, 2-ethylhexyl palmitate, methyl tallow fatty acid, octyldodecyl myristate, stearic acid Methyl, butyl stearate, 2-ethylhexyl stearate, isotridecyl stearate, methyl caprate, methyl myristate, methyl oleate, isobutyl oleate, octyl oleate, lauryl oleate, oleyl oleate, myristyl myristate, stearic acid Stearyl, 2-ethylhexyl oleate, decyl oleate, isobutyl oleate and other fatty acid and monohydric alcohol esters, sorbitan monolaurate, Vitan monopalmitate, sorbitan monostearate, sorbitan tristearate, sorbitan monooleate, sorbitan trioleate, polyethylene glycol monolaurate, polyethylene glycol monostearate, polyethylene glycol distearate, pentaerythritol monostearate, glycerin monostearate There are esters of fatty acids and polyhydric alcohols such as rate, glycerol distearate, glycerol tristearate, glycerol monooleate, hydrogenated beef tallow and hydrogenated castor oil. These fatty acid esters can be used alone or in combination. Preferably, glycerin fatty acid ester is used.
[0017]
Moreover, as said styrene-type expandable resin particle, the styrene-type resin particle containing a foaming agent can be used.
As a method for producing styrene-based expandable resin particles, for example, there are methods disclosed in JP-A-7-79376 and JP-A-8-253510. That is, first, a styrenic monomer is dispersed in an aqueous medium in the presence of a polymerization initiator and a suspending agent. Thereafter, a polymerization reaction is started, and a foaming agent is added before, during or during the polymerization reaction to produce styrene-based expandable resin particles.
[0018]
As another manufacturing method, a styrene resin and a volatile foaming agent are melt-kneaded in an extruder, extruded from the pores of the die at the tip of the extruder, immediately introduced into water, rapidly cooled, and unfoamed. There is a method for producing styrene-based expandable resin particles by granulating the particles.
In addition, the styrene resin is melt-kneaded in an extruder to obtain particles having a size of 0.5 to 5 mg / piece by methods such as strand cutting, hot cutting, and underwater cutting. Disperse in a closed container in an aqueous medium in the presence of a suspending agent. Thereafter, there is a method for producing styrene-based expandable resin particles by impregnating resin particles with a volatile foaming agent (Japanese Patent Laid-Open No. 2000-178373).
[0019]
As the blowing agent used for impregnation with the above dye, aliphatic hydrocarbons such as propane, normal butane, isobutane, normal pentane, isopentane, neopentane, hexane, etc. having a boiling point of 90 ° C. or lower, or alicyclic rings such as cyclobutane, cyclopentane, etc. Group hydrocarbons.
When the boiling point exceeds 90 ° C., the styrenic expandable resin particles may coagulate with each other when impregnated with the dye. More preferably, it is an aliphatic hydrocarbon or alicyclic hydrocarbon having a boiling point of 60 ° C. or less. These foaming agents can be used alone or in combination. The foaming agent used at the time of impregnation with the dye may be the same as or different from the foaming agent already contained in the styrenic foamable resin particles.
[0020]
Moreover, it is preferable that the addition amount of the said foaming agent used at the time of dye impregnation is 1-10 weight part with respect to 100 weight part of styrene-type expandable resin particles.
When the amount of the foaming agent added is less than 1 part by weight, the styrenic foamable resin particles may not be completely impregnated with the dye. On the other hand, when the amount exceeds 10 parts by weight, the styrene-based expandable resin particles may coagulate with each other. More preferably, it is 2 to 5 parts by weight.
[0021]
Examples of the dye include azo dyes, anthraquinone dyes, azine dyes, and quinoline dyes. The amount of the dye is preferably 0.001 to 1 part by weight with respect to 100 parts by weight of the styrene-based expandable resin particles. If the amount of the dye is less than 0.001 part by weight, the styrenic expandable resin particles may not be colored as desired. On the other hand, when the amount exceeds 1 part by weight, the styrenic expandable resin particles may not be sufficiently impregnated with the dye.
[0022]
The particle diameter of the dye preferably passes through a 100 mesh sieve. With a dye that does not pass through a 100 mesh sieve, the impregnation property of the styrenic foamable resin particles may be deteriorated.
[0023]
Moreover, it is preferable to use the said airtight container which can be sealed, for example, what can be stirred and mixed in a container and can be heated. Examples of such a sealed container include an autoclave with a stirrer and a mixer that can be sealed.
[0024]
Moreover, there is no restriction | limiting in the injection | throwing-in order of the said dye, fatty-acid ester, water, and a foaming agent. However, the foaming agent is preferably added after a dye or a fatty acid ester is mixed or coated on the surface portion of the styrenic foamable resin particles. In this case, the above-mentioned dye can be impregnated into the styrene-based expandable resin particles without color unevenness. Further, the dye, fatty acid ester and water may be mixed or coated on the styrenic expandable resin particles in advance before being put into the sealed container. The foaming agent may be added before heating, during heating, or after reaching a predetermined temperature, or may be added in multiple times.
[0025]
Next, the water content is preferably 0.005 to 1 part by weight with respect to 100 parts by weight of the styrenic expandable resin particles.
In this case, the styrene-based expandable resin particles can be colored almost uniformly. More preferably, the content is 0.01 to 0.5 parts by weight.
[0026]
Next, the fatty acid esters are preferably 0.001 to 1 part by weight with respect to 100 parts by weight of the styrenic foamable resin particles.
If the amount is less than 0.001 part by weight, the styrenic foamable resin particles may not be sufficiently impregnated with the dye. On the other hand, when the amount exceeds 1 part by weight, the surface of the colored styrene-based expandable resin particles becomes too plastic, which may cause condensation. More preferably, the content is 0.01 to 0.5 parts by weight.
[0027]
Next, the melting point of the fatty acid esters is preferably 70 ° C. or lower.
When the melting point of the fatty acid ester exceeds 70 ° C., the styrenic expandable resin particles may not be sufficiently impregnated with the dye.
[0028]
Next, the heating temperature in the sealed container is preferably 20 to 80 ° C. (Claim 5).
When the heating temperature exceeds 80 ° C., the styrene-based expandable resin particles may start to foam, and the desired colored styrene-based expandable resin particles may not be obtained. On the other hand, when the temperature is lower than 20 ° C., the styrenic foamable resin particles may not be sufficiently impregnated with the dye.
[0029]
The time for impregnating the styrenic expandable resin particles with the dye is preferably 0.5 hours or more.
If it is less than 0.5 hour, the styrenic expandable resin particles may not be sufficiently impregnated with the dye.
In order to shorten the dye impregnation time, the heating temperature should be as high as possible.
[0030]
【Example】
Next, the Example which manufactures colored styrene-type expandable resin particle is shown.
In this example, the colored styrene foam resin particles are produced by heating the styrene foam resin particles, the dye and the foaming agent in a sealed container at a temperature lower than the foaming temperature of the styrene foam resin particles. Stirring while stirring, impregnating styrenic foamable resin particles with dye and coloring styrene foam sex This is a method for producing resin particles. In addition, the impregnation with the dye is performed in the presence of 0.001 to 2 parts by weight of water in the sealed container and 0.001 to 2 parts by weight with respect to 100 parts by weight of the styrenic expandable resin particles.
[0031]
Hereinafter, the manufacturing method of the colored styrene-based expandable resin particles will be described in detail.
First, three types of styrenic expandable resin particles A to C were prepared by the following method.
(Styrene-based expandable resin particles A)
In a 50 liter autoclave with a stirrer, 18 liters of ion-exchanged water, 63 g of tricalcium phosphate (made by Taihei Chemical Industrial Co., Ltd.) as a poorly water-soluble inorganic suspending agent, and dodecylbenzenesulfone as a surfactant Sodium sulfate (manufactured by Tokyo Chemical Industry Co., Ltd.) 0.54 g was added.
[0032]
Next, under stirring, benzoyl peroxide (manufactured by NOF Corporation, purity 75%) 45 g (33.75 g in terms of pure product), t-butylperoxy 2-ethylhexyl carbonate 27 g, and organic bromine compound as a polymerization initiator 1,2,5,6,9,10-hexabromocyclododecane (108 g) and 18 kg of styrene monomer in which 180 g of cured beef tallow was dissolved as a plasticizer were added.
[0033]
Next, the mixture was allowed to stand at room temperature for 30 minutes under stirring, and then the temperature was raised to 90 ° C. over 1 hour and a half, and further raised to 100 ° C. over 6 hours and a half. During this time, 1.7 kg of butane was press-fitted into the autoclave 5 hours after reaching 90 ° C. Thereafter, the temperature was further raised to 110 ° C. over 3 hours, and the temperature was maintained at 110 ° C. for 5 hours under stirring. Then, it cooled to 30 degreeC over 4 hours, and produced the styrene-type expandable resin particle.
[0034]
Furthermore, the styrene-based expandable resin particles were dehydrated with a centrifuge, and water adhering to the surface was removed with a fluidized dryer. Thereafter, sieving foamed resin particles A having a mesh size of 0.7 mm to 1.4 mm were obtained by sieving with 0.7 mm and 1.4 mm sieves.
[0035]
(Styrene-based expandable resin particles B)
In a 50 liter autoclave equipped with a stirrer, 20 liters of ion exchange water, 80 g of tricalcium phosphate (made by Taihei Chemical Industrial Co., Ltd.) as a poorly water-soluble inorganic suspending agent, and dodecylbenzenesulfone as a surfactant 0.8 g of sodium acid (manufactured by Tokyo Chemical Industry Co., Ltd.) was added.
Then, under stirring, 45 g of t-butylperoxy 2-ethylhexanoate as a polymerization initiator, 27 g of t-butylperoxy 2-ethylhexyl carbonate, 270 g of cyclohexane as a plasticizer and 135 g of cured beef tallow are dissolved. 18 kg of monomer was charged.
[0036]
Next, the mixture was allowed to stand at room temperature for 30 minutes under stirring, and then the temperature was raised to 90 ° C. over 1 hour and a half, and further raised to 100 ° C. over 5 hours and a half. During this time, 1.7 kg of butane was injected into the autoclave 4 hours after reaching 90 ° C. Thereafter, the temperature was further raised from 100 ° C. to 110 ° C. over 1 hour and a half, and the temperature was kept at 110 ° C. for 2 hours under stirring. Then, it cooled to 30 degreeC over 4 hours, and produced the styrene-type expandable resin particle.
[0037]
Furthermore, the styrene-based expandable resin particles were dehydrated with a centrifuge, and water adhering to the surface was removed with a fluidized dryer. Thereafter, sieving foamed resin particles B having a particle size of 0.7 to 1.4 mm were obtained by sieving with sieves having an opening of 0.7 mm and 1.4 mm.
[0038]
(Styrene-based expandable resin particles C)
In a 50 liter autoclave with a stirrer, 18 liters of ion-exchanged water, 63 g of tricalcium phosphate (made by Taihei Chemical Industrial Co., Ltd.) as a poorly water-soluble inorganic suspending agent, and dodecylbenzenesulfone as a surfactant Sodium sulfate (manufactured by Tokyo Chemical Industry Co., Ltd.) 0.54 g was added.
Next, under stirring, 45 g of t-butylperoxy 2-ethylhexanoate as a polymerization initiator, 27 g of t-butylperoxy 2-ethylhexyl carbonate, and 180 g of phthalic acid-di-2-ethylhexyl as a plasticizer. 18 kg of dissolved styrene monomer was added.
[0039]
Next, the mixture was allowed to stand at room temperature for 30 minutes under stirring, then heated to 90 ° C. over 1 hour and a half, and further heated to 110 ° C. over 5 hours. During this time, 1.7 kg of butane was pressed into the autoclave 3 and a half hours after reaching 90 ° C. Thereafter, the temperature was further maintained at 110 ° C. for 4 hours under stirring. Then, it cooled to 30 degreeC over 4 hours, and produced the styrene-type expandable resin particle.
[0040]
Furthermore, the styrene-based expandable resin particles were dehydrated with a centrifuge, and water adhering to the surface was removed with a fluidized dryer. Thereafter, sieving foamed resin particles C having a particle size of 0.7 to 1.4 mm were obtained by sieving with a sieve having an opening of 0.7 mm and 1.4 mm.
[0041]
Next, the styrenic foamable resin particles A to C were colored and foam-molded as follows.
Example 1
500 g of styrene foam resin particles A as the styrene foam resin particles, 1.0 g of “Oil Blue 630” (Solvent Blue 36) manufactured by Orient Chemical Industry as a blue dye, and glycerin tristearate (Fatty acid esters) 0.5 g (melting point: 65-69 ° C.) and 0.5 g of water were placed in an autoclave equipped with a stirrer having an internal volume of about 3 L and mixed with stirring for 10 minutes.
[0042]
Next, the temperature was raised to 70 ° C. over 30 minutes, and 15 g of butane (a mixture of about 70% normal butane and about 30% isobutane) as a blowing agent was added into the autoclave. After the addition, stirring was further continued at 70 ° C. for 3 hours, followed by cooling to obtain blue colored styrene-based expandable resin particles.
[0043]
Next, the colored styrene-based expandable resin particles were expanded to a bulk density of 33 g / l with a 30 L batch type expansion machine to obtain pre-expanded particles. Subsequently, the obtained pre-expanded particles are left to stand (aged) at room temperature for 1 day, filled in a 25 × 75 × 300 mm mold, and heat-molded for 20 seconds at a steam blowing pressure of 0.07 MPa, and styrene-based foam Got.
[0044]
(Example 2)
In this example, the amount of water added in Example 1 was changed to 0.01 g, and colored styrene-based expandable resin particles were produced in the same manner as in Example 1 except that the colored styrene-based expandable resin particles were foam-molded. Thus, a foamed molded product was obtained.
[0045]
(Example 3)
In this example, the amount of water added in Example 1 was changed to 0.04 g, and the others were produced in the same manner as in Example 1 to produce colored styrene-based expandable resin particles. Thus, a foamed molded product was obtained.
[0046]
Example 4
In this example, the amount of water added in Example 1 was changed to 4.0 g, and colored styrene-based expandable resin particles were produced in the same manner as in Example 1 except that the colored expandable resin particles were foam-molded. Foam molding was obtained.
[0047]
(Example 5)
In this example, the amount of water added in Example 1 was changed to 7.5 g, and other colored styrene-based expandable resin particles were produced in the same manner as in Example 1, and the colored expandable resin particles were foam-molded. A foamed molded product was obtained.
[0048]
(Example 6)
In this example, the amount of glycerin tristearate added in Example 1 was changed to 2.5 g, and colored styrene-based expandable resin particles were prepared in the same manner as in Example 1, and the colored expandable resin particles were expanded. Molded to obtain a foamed molded product.
[0049]
(Example 7)
In this example, the amount of glycerin tristearate added in Example 1 was changed to 7.5 g, and colored styrene-based expandable resin particles were produced in the same manner as in Example 1 except that the colored expandable resin particles were expanded. Molded to obtain a foamed molded product.
[0050]
(Example 8)
In this example, glycerin tristearate (melting point: 65-69 ° C.) of Example 1 was changed to glycerin distearate (melting point: 61 ° C.), and colored styrene-based expandable resin particles were prepared in the same manner as in Example 1. Then, the colored foamable resin particles were foam-molded to obtain a foam-molded product.
[0051]
Example 9
In this example, the glycerin tristearate (melting point 65-69 ° C.) of Example 1 was changed to glycerin tri-2-ethylhexylate (melting point −30 ° C.), and the others were the same as in Example 1, and the colored styrene foam Resin particles were produced, and the colored foamed resin particles were foam-molded to obtain a foam-molded article.
[0052]
(Example 10)
In this example, the glycerin tristearate (melting point 65-69 ° C.) of Example 1 was changed to sorbitan monooleate (melting point 9 ° C.), and the others were the same as in Example 1 to produce colored styrene-based foamable resin particles. Then, the colored foamable resin particles were foam-molded to obtain a foam-molded product.
[0053]
(Example 11)
In this example, the glycerin tristearate of Example 1 (melting point 65-69 ° C.) was changed to hydrogenated castor oil (melting point 84 ° C.), and the others were the same as in Example 1 to produce colored styrene-based expandable resin particles. The colored foamable resin particles were foam-molded to obtain a foam-molded article.
[0054]
(Example 12)
In this example, the amount of butane added in Example 1 was changed to 5 g, and colored styrene-based expandable resin particles were produced in the same manner as in Example 1 except that the colored expandable resin particles were subjected to foam molding and subjected to foam molding. Got the body.
[0055]
(Example 13)
In this example, the amount of butane added in Example 1 was changed to 35 g, and colored styrene-based expandable resin particles were produced in the same manner as in Example 1 except that the colored expandable resin particles were subjected to foam molding and subjected to foam molding. Got the body.
[0056]
(Example 14)
In this example, 15 g of butane of Example 1 (a mixture of about 70% normal butane and about 30% isobutane), 7.5 g of pentane (a mixture of about 80% normal pentane and about 20% isopentane) and butane (about about normal butane). 70%, isobutane approximately 30% mixture) The mixture was changed to 7.5 g of the mixture. Otherwise, colored styrene-based expandable resin particles were produced in the same manner as in Example 1, and the colored expandable resin particles were foamed and foamed. A molded body was obtained.
[0057]
(Example 15)
In this example, the butane of Example 1 (a mixture of about 70% normal butane and about 30% isobutane) was changed to pentane (a mixture of about 80% normal pentane and about 20% isopentane), and the others were the same as in Example 1. Colored styrene-based expandable resin particles were prepared, and the colored expandable resin particles were foam-molded to obtain a foam-molded product.
[0058]
(Example 16)
In this example, the blue dye of Example 1 was changed to a red dye, and other than in Example 1, colored styrene-based expandable resin particles impregnated with a red dye were prepared, and the colored expandable resin particles were Foam molding was performed to obtain a foam molding. As the red dye, 1.0 g of “OPLAS RED 330” (Solvent Red 111) manufactured by Orient Chemical Industries was used.
[0059]
(Example 17)
In this example, the blue dye of Example 1 was changed to a yellow dye, and others were made in the same manner as in Example 1 to produce colored styrene-based expandable resin particles impregnated with a yellow pigment. Foam molding was performed to obtain a foam molding. As the yellow dye, 1.0 g of “OPLAS YELLOW 136” (Solvent Yellow 33) manufactured by Orient Chemical Industries was used.
[0060]
(Example 18)
In this example, the styrenic foamable resin particles A of Example 1 were changed to styrenic foamable resin particles B, and other colored styrene foamable resin particles were produced in the same manner as in Example 1, and the colored foamable properties were Resin particles were subjected to foam molding to obtain a foam molded article.
[0061]
(Example 19)
In this example, the styrenic foamable resin particles A of Example 1 were changed to styrenic foamable resin particles C, and colored styrene foamable resin particles were produced in the same manner as in Example 1 except that Resin particles were subjected to foam molding to obtain a foam molded article.
[0062]
Next, with respect to the colored styrene-based expandable resin particles obtained in Examples 1 to 19, the charged state, the dye impregnation state, and the coagulation amount were evaluated by the following methods. Moreover, the fusion | melting degree of the foaming molding obtained in the said Examples 1-19 was evaluated.
[0063]
(Charged state)
After producing the colored styrene-based expandable resin particles, the number of colored styrene-based expandable resin particles adhering to the inner wall of the autoclave was measured. The case where the number of colored styrene-based expandable resin particles adhering to the inner wall of the autoclave is less than 1/20 of the total number of colored styrene-based expandable resin particles is ◎, and the case where it is 1/20 or more and less than 1/10 is ◯, The case where n was 1/10 or more was evaluated as x. The results are shown in Table 1.
[0064]
(Impregnated state)
The colored styrenic expandable resin particles 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 little 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.
[0065]
(Condensation amount)
The above colored styrene foam resin particles are sieved with a 1.7 mm mesh JIS sieve, and the number of colored styrene foam resin particles remaining on the sieve is divided by the number of all styrene foam resin particles passed through the sieve. And calculated as the amount of condensation. The results are shown in Table 1.
[0066]
(Fusion degree)
The foamed molded body was cut, and the tear generated at the interface of the pre-expanded particles in the cross section was visually observed. The case where tearing occurred at all the interfaces of the pre-expanded particles was evaluated as 0, and the case where tearing did not occur at the interface of the pre-expanded particles was evaluated as 1. In addition, evaluation was performed in ten steps of every 0.1 from 0 to 1. The results are shown in Table 1.
[0067]
[Table 1]

[0068]
As is known from Table 1, the colored styrene-based expandable resin particles obtained by the production method of this example (Examples 1 to 19) have little charge, good dye impregnation, and very little condensation. It was. Further, the foamed molded article obtained by foaming the colored styrene-based expandable resin particles had strong fusion.
Moreover, in the manufacturing method of the colored styrene-type expandable resin particle of Examples 1-19, an apparatus is not contaminated with a dye and it is not necessary to use an especially big apparatus.
[0069]
As described above, according to this example, the colored styrene-based resin particles can be impregnated with the styrenic expandable resin particles without causing color unevenness, are hard to condense when impregnated with the dye, and have excellent fusion property during foam molding. A method for producing expandable resin particles can be provided.
[0070]
Next, Comparative Examples 1 to 6 shown below were performed for comparison.
(Comparative Example 1)
In this example, without adding water, colored styrene-based expandable resin particles were produced in the same manner as in Example 1, and the colored expandable resin particles were foam-molded to obtain a foam-molded article.
[0071]
(Comparative Example 2)
In this example, the amount of water added in Example 1 was changed to 15 g. Other than that in Example 1, colored styrene-based expandable resin particles were produced, and the colored expandable resin particles were subjected to foam molding to perform foam molding. Got the body.
[0072]
(Comparative Example 3)
In this example, the colored styrene-based expandable resin particles were prepared in the same manner as in Example 1 except that the fatty acid esters of Example 1 were not added. Got the body.
[0073]
(Comparative Example 4)
In this example, the colored styrene-based expandable resin particles were prepared in the same manner as in Example 1 except that the foaming agent of Example 1 was not added. Got.
[0074]
(Comparative Example 5)
In this example, the colored styrene-based expandable resin particles were prepared in the same manner as in Example 1 except that the fatty acid esters and the foaming agent of Example 1 were not added, and the colored expandable resin particles were foam-molded. Thus, a foamed molded product was obtained.
[0075]
(Comparative Example 6)
In this example, 0.5 g of toluene was used in place of the fatty acid esters of Example 1, and other colored styrene-based expandable resin particles were produced in the same manner as in Example 1, and the colored expandable resin particles were expanded. Molded to obtain a foamed molded product.
[0076]
Next, in the same manner as the colored styrene foam resin particles of Examples 1 to 19, the charged state of the colored styrene foam resin particles prepared in Comparative Examples 1 to 6, the dye impregnation state, and The amount of condensation was evaluated. In addition, the degree of fusion of the foam molded bodies obtained in Comparative Examples 1 to 6 was evaluated in the same manner as the foam molded bodies of Examples 1 to 19. The results are shown in Table 2.
[0077]
[Table 2]

[0078]
As is known from Table 2, the colored styrene-based expandable resin particles obtained in Comparative Examples 1 and 6 were highly charged and had uneven color. Moreover, in Comparative Example 2 and Comparative Example 6, condensation of colored styrene-based expandable resin particles occurred. Further, in Comparative Examples 3 to 5, the dye impregnation property was poor. Furthermore, the foamed molded products obtained in Comparative Examples 3 to 6 had a weak fusion and had a problem in strength.

Claims

Stir styrene foam resin particles, dye and foaming agent in a sealed container while heating at a temperature lower than the foaming temperature of the styrene foam resin particles to impregnate the styrene foam resin particles with the dye. a method for producing a colored styrenic expandable resin beads Te,
In the impregnation of the dye, the water content in the sealed container is 0.001 to 2 parts by weight with respect to 100 parts by weight of the styrene-based expandable resin particles and in the presence of fatty acid esters. A method for producing colored styrene-based expandable resin particles.

2. The method for producing colored styrene foam resin particles according to claim 1, wherein the water content is 0.005 to 1 part by weight with respect to 100 parts by weight of the styrene foam resin particles.

3. The method for producing colored styrene-based expandable resin particles according to claim 1, wherein the fatty acid esters are 0.001 to 1 part by weight with respect to 100 parts by weight of the styrene-based expandable resin particles. .

The method for producing colored styrene-based expandable resin particles according to any one of claims 1 to 3, wherein the fatty acid esters have a melting point of 70 ° C or lower.

The method for producing colored styrene-based expandable resin particles according to any one of claims 1 to 4, wherein the heating temperature in the sealed container is 20 to 80 ° C.