JP3718752B2 - Thermochromic water-based ballpoint pen ink and ballpoint pen using the same - Google Patents

Description

上記において、０．５μｍ≦Ｄ≦２０μｍの累計９８％、平均粒子径４．２μｍ である。
【００３４】
得られたマイクロカプセルを顕微鏡で観察した所、 凹部を有する半球偏平状のカプセルであることを確認した。粒子径が大きくなるにつれて偏平性は大きくなっていた。熱色性マイクロカプセル顔料の熱変色性は、２７℃以下でマゼンタ色、３２℃以上で無色、両温度間では変色の過渡域であった。
【００３５】
前記得られたマイクロカプセルスラリーを着色剤として水性ボールペン用インキを調製した。以下にその配合例を示す。

【００３６】
前記インキの粘度をＥＭＤ型粘度計にて２５℃で測定した結果、１ｒｐｍで、１０２０ｍ．Ｐａ．ｓ、１００ｒｐｍで８４ｍ．Ｐａ．ｓ、の値を示し、剪断減粘指数ｎ０．４８であった。
尚、ノプコＳＷ−ＷＥＴ−３６６は、サンノプコ社製ノニオン系浸透性付与剤、ノプコ８０３４は、同社の変性シリコーン系消泡剤であり、プロキセルＸＬ−２はＩ．Ｃ．Ｉ社製ベンゾチアゾリン系防腐剤である。
【００３７】
ボールペンの作製
０．８ｍｍのステンレス鋼ボールを用い、ボール収容部の内径とボール外径との差Ｓ（Ａ−Ｂ）＝２０μｍ、軸方向の移動可能なスペースＣ＝７０μｍのスペースを配してなる切削型ボールペンチップを用いた。前記熱変色性インキを内径３．３ｍｍのポリプロピレン製パイプに０．８ｇ吸引充填し、樹脂製ホルダーを介して前記ボールペンチップと連結させた。
ついで前記ポリプロピレン製パイプの尾部より、ポリブテンベースの粘弾性を有するインキ追従体（液栓）を充填し、外装ペン軸、キャップ、口金、尾栓を組み込んだ後、遠心処理を行い脱エアー処理をし、熱変色性水性ボールペンを得た。
前記熱変色性水性ボールペンでレポート用紙に筆記したところ、、書き出しから良好なピンク濃度と筆跡が得られた。ついで、連続して筆記を続けたが、インキのぼた落ち、著しい線割れ、かすれ、筆跡のスキップ等の好ましくない現象もなくインキをすべて消費することができた。さらに、筆記時における筆圧によるマイクロカプセルの破壊・劣化を確認するため、前記筆記した紙面上のインキを回収し、顕微鏡にてカプセルの外観を調べた所、カプセルの破壊は全く観察されなかった。
【００３８】
筆跡の熱変色性を試験した結果、２７℃以下でマゼンタ色、３２℃以上で無色の熱変色性を示した。インキ化の原料として用いたマイクロカプセルスラリーと同一の熱変色性を示し、熱変色性の機能が筆記後も維持されていることが確認できた。
尚、別途同一仕様のボールペンを調製し、５０℃恒温室にて３０日間、正立、倒置、横置き状態で放置した後、筆記テストを行った結果、前記初期テストと同様、良好な結果を得た。
【００３９】
実施例２
２−（４−ジエチルアミノ−２−エトキシフェニル）−３−（１−エチル−２−メチルインドール−３−イル）−４−アザフタリド２．５部、２，２−ビス（４−ヒドロキシフェニル）ヘキサフルオロプロパン５部、ステアリン酸ネオペンチル５０部からなる熱変色性組成物と耐光性付与剤としてチヌビン３２６を１部、ついで膜材として芳香族ジイソシアネートとグリーコールと反応して得られたオリゴマー１５部を助溶剤３０部と共に加温溶解し、あらかじめ７０℃加温しておいた水性保護コロイド媒体１００部中に平均粒径が２．５μｍになるようにホモミキサーで乳化した。
ついで、脂肪族変性ポリアミン硬化剤５部を添加し９０℃で５時間攪拌を続け、助溶剤を蒸発除去させて界面重合法によるマイクロカプセル分散液を得た。マイクロカプセルを濃縮化する目的で遠心分離処理を行い、スラリー状の含水ケーキ９８部を得た。当該カプセルスラリーの含水率を測定した所３２％であった。
【００４０】
さらに粒度分布を測定するため遠心沈降式自動粒度分布測定装置（堀場製作所製、ＣＡＰＡ−３００）を用いた。粒子径をＤとする時、粒子径と占有体積％〔（ ）内に示す〕の関係は下記の通りであった。

上記０．５μｍ≦Ｄ≦２０μｍの累計９７％、平均粒子径２．７μｍであった。
【００４１】
得られたマイクロカプセルを顕微鏡で観察したところ、凹部を有する半球偏平状のカプセル（図２〜５参照）であることを確認した。粒子径が大きくなるにつれて偏平性は大きくなっていた。熱色性マイクロカプセル顔料の熱変色性は、１４℃以下でブルー色、３２℃以上で無色で、両温度間では広いヒステリシス特性を持ち、前記２状態の色が可能であった。前記得られたマイクロカプセルスラリーを着色剤として水性ボールペン用インキを調製した。以下にその配合例を示す。

【００４２】
前記インキの粘度をＥＭＤ型粘度計にて２５℃で測定した結果、１ｒｐｍで、１３０６ｍ．Ｐａ．ｓ、１００ｒｐｍで１２２ｍ．Ｐａ．ｓ、剪断減粘指数ｎ０．４９であった。
【００４３】
ボールペンの作製
０．５ｍｍのステンレス鋼ボールを用い、ボール収容部の内径とボール外径との差Ｓ（Ａ−Ｂ）＝２０μｍ、軸方向の移動可能なスペースＣ＝４０μｍのスペースを配してなる切削型ボールペンチップを用いた。前記熱変色性インキを内径３．３ｍｍのポリプロピレン製パイプに０．８ｇ吸引充填し、樹脂製ホルダーを介して前記ボールペンチップと連結させた。ついで前記ポリプロピレン製パイプの尾部より、ポリブテンベースの粘弾性を有するインキ追従体（液栓）を充填し、外装ペン軸、キャップ、口金、尾栓を組み込んだ後、遠心処理を行い脱エアー処理をし、熱変色性水性ボールペンを得た。
前記熱変色性水性ボールペンを用いてレポート用紙に筆記したところ、、書き出しから良好なピンク濃度と筆跡が得られた。ついで、連続して筆記を続けたが、インキのぼた落ち、著しい線割れ、かすれ、筆跡のスキップ等の好ましくない現象もなくインキをすべて消費することができた。
【００４４】
さらに、筆記時における筆圧によるマイクロカプセルの破壊・劣化を確認するため、前記筆記した紙面上のインキを回収し、顕微鏡にてカプセルの外観を調べた所、カプセルの破壊は全く観察されなかった。
筆跡を熱変色性を試験した結果、１４℃以下でブルー色、３２℃以上で無色であり、両温度間でのヒステリシス特性についてもインキ化の原料として用いたカプセルスラリーの変色性と同一の変色性を示した。
【００４５】
実施例３
実施例１と同一のカプセルスラリー（含水率３８％）を用い、インキ化配合における剪断減粘性樹脂の種類をサクシノグルカンに変え、かつ添加量も適切な粘度となるよう変更した。
【００４６】
ボールペンの仕様は実施例１と同様の方法に従った。以下にインキの配合例を示す。

【００４７】
実施例４
実施例１と同一のカプセルスラリー（含水率３８％）を用い、インキ化配合における剪断減粘性樹脂の種類を架橋型アクリル系水溶性樹脂（住友精化製、アクペックＨＶ５０１〕に変えると共にその重量も変えた。
【００５３】
ボールペンの仕様は実施例１と同様の方法に従った。尚以下にインキの配合例を示す。

【００４８】
実施例５
実施例２と同一のインキを用い、ボールペンチップ部を切削タイプからパイプの押圧変形タイプ（図６〜図７）方式へ変更してボールペンを作製した。即ち、０．７ｍｍのステンレス鋼ボールを用い、ボール収容部は、パイプ内径とボール外径との差Ｓ（Ａ−Ｂ）＝３０μｍ、軸方向の移動可能なスペースＣ＝２５μｍのスペースを有するボールペンチップを用いた。
前記熱変色性ボールペンインキを内径３．３ｍｍのポリプロピレン製チューブに０．８ｇ吸引充填し、樹脂製ホルダーを介して前記ボールペチップと連結させた。ついで前記ポリプロピレン製チューブの尾部より、ポリブテンベースの粘弾性を有するインキ追従体（液栓）を充填し、外装ペン軸、キャップ、口金、尾栓を組み込んだ後、遠心処理を行い脱エアー処理をし、熱変色性水性ボールペンを得た。
【００４９】
前記熱変色性水性ボールペンを用いてレポート用紙に筆記したところ、書き出しから良好なピンク濃度と筆跡が得られた。ついで、連続して筆記を続けたが、インキのぼた落ち、著しい線割れ、かすれ、筆跡のスキップ等の好ましくない現象もなくインキをすべて消費することができた。さらに、筆記時における筆圧によるマイクロカプセルの破壊・劣化を確認するため、前記筆記した紙面上のインキを回収し、顕微鏡にてカプセルの外観を調べた所、カプセルの破壊は全く観察されなかった。
筆跡を熱変色性を試験した結果、１４℃以下でブルー色、３２℃以上で無色であり、両温度間でのヒステリシス特性についてもインキ化の原料として用いたカプセルスラリーの変色性と同一の変色性を示した。
【００５０】
実施例６
実施例２のマイクロカプセルスラリーを用いて、インキ配合中に一般の蛍光顔料（ピンク色）を配合しカラーからカラーへの変色性を有するインキを調製した。尚、蛍光顔料ＳＷ−２７は、シンロイヒ社製ピンク色蛍光顔料である。
以下にインキの配合例を示す。

【００５１】
上記インキを０．５ｍｍのステンレス鋼ボールを用い、ボール収容部の内径とボールとの差Ｓ（Ａ−Ｂ）＝２０μｍ、軸方向の移動可能なスペースＣ＝４０μｍのスペースを有する切削型ボールペンチップを先端部に有するボールペンを用いた。
前記熱変色性ボールペンインキを内径３．３ｍｍのポリプロピレン製チューブに０．８ｇ吸引充填し、樹脂製ホルダーを介して前記ボールペチップと連結させた。ついで前記ポリプロピレン製チューブの尾部より、ポリブテンベースの粘弾性を有するインキ追従体（液栓）を充填し、外装ペン軸、キャップ、口金、尾栓を組み込んだ後、遠心処理を行い脱エアー処理をし、熱変色性水性ボールペンを得た。
【００５２】
レポート用紙に筆記した所、書き出しから良好なパープル色の筆跡が得られた。ついで、連続して筆記を続けたが、インキのぼた落ち、著しい線割れ、かすれ、筆跡のスキップ等の好ましくない現象もなくインキをすべて消費することができた。さらに、筆記時における筆圧によるマイクロカプセルの破壊・劣化を確認するため、前記筆記した紙面上のインキを回収し、顕微鏡にてカプセルの外観を調べた所、カプセルの破壊は全く観察されなかった。
筆跡を熱変色性を試験した結果、１４℃以下でパープル色、３２℃以上で蛍光ピンクであり、両温度間でのヒステリシス特性についてもインキ化の原料として用いたカプセルスラリーの変色性と同一の変色性を示した。
【００５３】
実施例７
２−（２−クロロアニリノ）−６−ジブチルフルオラン３部、１，１−ヘキシリデンビスフェノール８部、ステアリン酸ｎ−ブチル３０部、パルミチン酸ｎ−ブチル２０部、チヌビン３２８（チバガイギー製、紫外線吸収剤）２部からなる熱変色性組成物とフェノールノボラック系エポキシ樹脂２０部、助溶剤５０部を加え、７０℃にて加温溶解した内包物溶液を水性保護コロイド樹脂媒体中にホモミキサーにて乳化分散した。乳化時の粒径の設定は平均１０μｍになるようホモミキサーの回転数を調整しながら行った。ついで、水溶性のジアミン化合物を硬化剤として加え、９０℃にて８時間攪拌続けカプセル化を完了した。
反応後のカプセル分散液を２倍量の水で希釈し、ついで６２５メッシュのステンレスメッシュで濾過処理を行った後、遠心分離法にてマイクロカプセルを含水ケーキとして１０５ｇ単離した。当該ケーキは含水率３８％であった。
【００５４】
実施例１と同様の方法にてマイクロカプセルの粒度分布を測定した。

上記は０．５μｍ≦Ｄ≦２０μｍにおいて、累計 ９７％、平均体積平均粒径１２μｍであった。
【００５５】
得られたマイクロカプセルを顕微鏡で観察した所、凹部を有する半球偏平状のカプセルであることを確認した。
【００５６】
熱変色性マイクロカプセル顔料の熱変色性は１２℃以下で黒色、１７℃以上で無色であった。両温度間では変色の過渡域を示した。得られたマイクロカプセル顔料を用いて、実施例１と同様のインキ配合、及びボールペンの仕様でボールペンを作製した。レポート用紙に筆記した所、書き出しから良好なインキ吐出が観察され、筆跡濃度もまずまずの濃度であった。連続的に丸ループを書き続けた結果、すべて充填したインキを消費することができた。筆跡を５０℃の恒温槽に１０日放置した後、その変色性を調べた。その結果、熱変色性は１２℃以下で黒色、１７℃で無色であり、変色過渡域も含め、筆跡の変色機能における劣化は全くなかった。
【００５７】
比較例１
実施例１の粒子分布のみを変えるため、乳化時の平均粒径を１５μｍと設定してマイクロカプセル化した点を除いて、全く実施例１と同様の手順でボールペンを作製した。得られたマイクロカプセルスラリーの粒度分布は下記の通りであった。

上記は０．５μｍ≦Ｄ≦２０μｍにおいて、累計 ８１％、平均粒子径１６μｍであった。
【００５８】
筆記試験をした所、書き出しからインキはかすれ気味で、暫く後インキは吐出し始めたが、濃度はきわめて薄く筆跡濃度としては、やや不満足なものであった。インキ０．１ｇが消費された所でかすれ気味になったため、ボールペンを解体しボール収容部内のインキ、とくにボール近傍のインキを顕微鏡で観察したところ、２５〜３０μｍの単核だが大きい粒子が密集していた。
【００５９】
比較例２
実施例１と同一のマイクロカプセルスラリーを使用し、インキ配合における剪断減粘性樹脂の配合量を増加させた。ボールペン仕様は実施例１と同様の方法で作製した。以下にインキの配合例を示す。

【００６０】
前記の如くして得た熱変色性水性ボールペンを用いて筆記試験をしたところ、書き出しからインキは全く吐出せず、暫く筆記をつづけても変化はなかった。インキ粘度を測定したところ下記の表に示す通り高粘度になっており、水性ボールに特有の剪断時における低粘度化が不十分なためと考えられる。
【００６１】
実施例１〜６、比較例１、２における熱変色性顔料の固形分含有率、平均粒子径、インキ粘度、剪断減粘性、ボール径、クリアランス、筆記試験における評価を表に示す。
【表１】

【００６２】
【発明の効果】
本発明は、熱変色性マイクロカプセル顔料を分散させた剪断減粘性の熱変色性インキ及びそれを用いたボールペンであり、スムーズな筆記感を満たし、均質で安定な熱変色性筆跡を持続して与えることができ、新たな軽便な筆記材を提供するものである。熱変色性材料の筆記材への適用として、熱変色性マイクロカプセル顔料をワックス等の賦形剤に分散させた固形筆記材が従来より開示されているが、筆記時の筆圧や磨耗により細幅の筆跡を持続して形成できないし、筆記感もスムーズでなく、画材分野への適用性を備えているとしても筆記具としての実用性は満たしていない。
【００６３】
本発明のボールペンは多方面に実用性を有している。
具体的に、本発明の水性による熱変色性ボールペンの応用用途を例示する。
（１）年賀状、クリスマスカード、グリーティングカードなどに熱変色性ボールペンで秘密のメッセージや絵柄を記入したり、又は図柄が変化するように一般のボールペンや印刷絵柄と組み合わせて変化に富んだカード類を作成することができる。
（２）同様に、秘密を要するメモを作成する時に、本発明のボールペンで記入することができる。変色点１０℃のような冷却時のみ発色する熱変色性材料を適用すれば、常温では消色状態となっているため、万一の紛失時にも第３者には記載内容を読まれずにすむ利点がある。
（３）本発明の熱変色性水性ボールペンは学習用に用いると特段の効果を示す。即ち、例えば、変色に関し大きなヒステリシス特性を有するものを適用したボールペンで問題集、テスト、ドリル、英単語和訳用に用いれば、一旦、解答や補足事項を熱変色性インキの着色状態で記入して学習したあと、再び復習をしたい場合や記憶を確認したい場合には、一旦、すべての記入事項を熱の印加により消去したうえで、完全にリセットされた状態で、再度問題に取りかかることができる。この操作は繰り返し何回でも行うことができるので、これまでにない有用な材料として学習分野向けの筆記具として利点がある。
（４）通常の筆記具的な使い方で用いることもできる。即ち常温では着色状態を維持しているような変色温度をもつ熱変色性インキ、例えば３３℃変色インキを用いれば一般の筆記具のように筆記したあと、その筆跡のカラフルな色変化を楽しむことがこともできる。かかる場合にはカラーから無色に変化するものに加え、カラーからカラーへ変色する２色性変化、或いは異なる変色温度と異なる色の熱変色性カプセルを用いることにより、息を吹きかけたり、手で温めたりして、温度変化に応じた多彩な色変化を楽しむことが可能となる。
【図面の簡単な説明】
【図１】マイクロカプセル顔料の一例の外形の模式説明図である。（Ａ）は外観を、（Ｂ）は、断面状態を示す。
【図２】マイクロカプセル顔料の他の例の外形の模式説明図である。（Ａ）は外観を、（Ｂ）は断面状態を示す。
【図３】マイクロカプセル顔料の他の例の外形の模式説明図である。（Ａ）は外観を、（Ｂ）は断面状態を示す。
【図４】マイクロカプセル顔料の他の例の外形の模式説明図である。（Ａ）は外観を、（Ｂ）は断面状態を示す。
【図５】マイクロカプセル顔料の他の例の外形の模式説明図である。（Ａ）は外観を、（Ｂ）は断面状態を示す。
【図６】本発明ボールペンのチップ部の一実施例の縦断面説明図である。
【図７】図６のＸ−Ｘ線断面図である。
【図８】本発明ボールペンのチップ部の他の例の縦断面説明図である。
【図９】図９のＸ−Ｘ線断面図である。
【図１０】本発明ボールペンのチップ部の他の例の縦断面説明図である。
【図１１】本発明ボールペンの一実施例の縦断面説明図である。
【符号の説明】
１ ボールペン
２ ボール
３ ボール収容部
３１ 中心孔
３２ 導出溝
３３ ボール受け座
４ インキ収容部
５ マイクロカプセル顔料
５１ 壁膜
５２ 窪み
５３ 熱変色性組成物
６ 熱変色性水性ボールペンインキ
７ インキ追従体
Ａ 内径
Ｂ 外径
Ｃ スペース[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a thermochromic water-based ballpoint pen ink and a ballpoint pen using the same.
[0002]
[Prior art]
Several proposals have been disclosed regarding water-based ballpoint pen inks that can be written by reducing the viscosity by shearing action caused by the rotation of the ball during writing (Japanese Patent Publication No. 64-8673 and Japanese Patent Publication No. 7-17882). Gazette).
However, no effective proposal has yet been disclosed for a water-based ballpoint pen that gives thermochromic handwriting.
[0003]
[Problems to be solved by the invention]
The present inventor has eagerly pursued a ballpoint pen ink containing a thermochromic microcapsule pigment and a ballpoint pen mechanism for effectively deriving the ballpoint pen ink, satisfying a smooth writing feeling and maintaining a uniform and stable thermochromic handwriting. It is intended to provide a thermochromic ballpoint pen ink that can be formed in this manner and a ballpoint pen using the same.
[0004]
Conventionally, a solid writing material in which a thermochromic microcapsule pigment is dispersed in an excipient such as wax has been disclosed in Japanese Patent Publication No. 51-48085, etc. Had a problem.
First, as a main reason, there was a problem of destruction of microcapsules due to writing pressure at the time of writing. That is, in a system in which a highly viscous oil-based ink is derived from an oil-based ballpoint pen mechanism, when a dispersion ink of a thermochromic microcapsule pigment is applied, the handwriting density is insufficient and the microcapsule pigment itself is used for writing. It tends to be destroyed by pressure, and a proper thermochromic handwriting cannot be formed continuously.
Such a phenomenon can be easily understood by considering that pressure-sensitive copying paper, so-called carbonless paper, can be copied to the bottom sheet side by writing with a ballpoint pen and breaking.
[0005]
In recent years, an aqueous ballpoint pen using an aqueous medium ink imparted with thixotropy has been put into practical use. This type of ink is characterized by a high viscosity when left standing and a low viscosity when high shearing during writing, and the ink ejection mechanism at the tip is a non-shear thinning oil-based ballpoint pen ink system. It is very different compared to That is, the difference between the inner diameter of the ball housing portion and the outer diameter of the ball is large, that is, the gap is large, and the ink whose viscosity is reduced by the shearing action passes through the gap by the capillary action and is transferred to the paper surface.
The present inventor has first secured the passage of the gap by adjusting the size of the microcapsule pigment particles to a predetermined particle range sufficient to pass through the gap. On the other hand, the viscosity at the time of ink writing is approximately 160 m. Pa. If it is less than s, it has been found that the capsule pigment particles move so as to slip out of the writing pressure and have pressure relaxation properties. It can be seen that as the viscosity of the ink becomes higher, the discharge property of the ink is inferior, and at the same time, the degree of escape from the writing pressure of the capsule pigment itself is reduced, so that the capsule pigment particles tend to be destroyed accordingly. It was.
[0006]
Furthermore, as a result of intensive research, the shape of the microcapsule pigment has a shape (see FIGS. 2 to 5) having a depression (concave portion) on the surface compared to a spherical body having a perfect circular cross section (see FIG. 1). It was found that the degree of destruction of the capsule itself was further alleviated even with this ink. Even if the microcapsule pigment having a dent (concave portion) is subjected to an external force (such as a pressure generated during writing), it is considered that the stress is caused by pressure relaxation by its own elastic deformation. In fact, in this type of thermochromic microcapsule pigment, the phase change of the thermochromic composition (homogeneous solution) that is the inclusion, that is, the liquid phase (color development) and the solid phase (extinguishment) due to temperature change. When the color is reversibly changed, the volume expansion coefficient of the inclusions changes accordingly, and at the same time, the capsule membrane is deformed by the internal pressure and follows.
Based on the above-mentioned knowledge, the present inventor constituted a ballpoint pen ink of an aqueous medium using a thermochromic microcapsule pigment, which has been considered difficult in the past, as a colorant, and applied it in combination with a specific ballpoint pen mechanism. We succeeded in forming a uniform handwriting that does not cause any deterioration of the color-changing function.
[0007]
A problem with the second thermochromic microcapsule pigment is handwriting density. In recent years, water-based ballpoint pens using fluorescent pigments, gold and silver pigments in addition to those using general dyes and pigments as colorants are also commercially available.
The biggest difference between the dye-based and pigment-based dyes as described above and the microencapsulated thermochromic pigment system relates to the color density of the pigment particles themselves.
[0008]
The thermochromic microcapsule pigment contains, as an inclusion, an electron donating color-forming organic compound such as a leuco dye and an electron accepting compound such as a phenolic compound, as well as the two types Various organic medium compounds having a polarity approximately 20 to 50 times the weight of the above compound are blended. As a result, the leuco dye that determines the original concentration has already been diluted approximately 20 to 50 times in the state of the inclusion composition.
[0009]
In an attempt to increase the concentration of the microcapsule pigment itself, the ratio of the leuco dye and the corresponding phenolic compound can be increased. However, an increase in the density of the pigment particles itself by such a technique causes a residual color at the time of decoloration with respect to the thermochromic function, resulting in a decrease in contrast at the time of the color change such as a lack of magic of handwriting.
As a result of earnestly examining the relationship between the solid content concentration and the handwriting concentration of the thermochromic microcapsule pigment, the present inventor found that the microcapsule pigment contained in the ink composition was in the range of 5 wt% to 45 wt%. The handwriting as a ballpoint pen can be formed. However, in the system of 5 to 15% by weight, there is no problem with the ink ejection property, but the handwriting density (concentration for making the thermochromic effect of the handwriting clearly visible) is insufficient, and the weight is substantially 15%. It is difficult to satisfy the concentration of the handwriting unless it is blended in an amount of more than 50%, and as the blending amount increases, there is a tendency to form a handwriting with a high concentration, but even if a shear thinning effect at the time of writing is added, 40% by weight Exceeding this tends to lower the ink ejection properties. It was found that the most preferable solid content concentration of the thermochromic microcapsule pigment was 20% by weight or more and 40% by weight or less in consideration of the ink discharge property, handwriting concentration, and shear thinning imparted to the ink. .
Further studies were made based on the above findings, and the present invention was completed by combining this with an appropriate ballpoint pen mechanism.
[0010]
[Means for Solving the Problems]
The thermochromic ballpoint pen ink which is the first invention will be described.
The ink of the present invention has (b) as an essential component. A homogeneous solution containing an electron-donating organic compound, an electron-accepting compound, and a reaction medium for adjusting the color change temperature as an essential component is coated with a wall film having depressions on at least a part of the outer surface, and the particle distribution is 0.5 μm. Occupies 95 vol% or more in the range of ~ 20μm The microcapsule pigment is made of an aqueous medium containing a thermochromic microcapsule pigment, (b) shear thinning substance, water and a water-soluble organic solvent, and the microcapsule pigment is in a dispersed state in the aqueous medium.
Furthermore ,heat Discolorable microcapsule pigment Wall film Is formed by interfacial polymerization or interfacial polycondensation method Become about ,heat Discoloration microcapsule pigment 15 to 45% by weight (solid content), shear thinning resin 0.1 to 0.5% by weight, water-soluble organic solvent 5 to 35% by weight, the balance is water, the viscosity is 40 -160 m. Pa. It is in the range of s (value at a rotational speed of 100 rpm in the EM type rotational viscometer) and satisfies the shear thinning index of 0.1 to 0.6.
[0011]
The shear thinning of the ink in the above is an experimental exponential equation (T = Kj) obtained from rheological measurements with a viscometer such as a shear stress value (T) and a shear rate (j) value. ⁿ : K and n are calculated constants) are n values calculated by fitting them. The n value is 0.1 to 0.6, preferably 0.20 to 0.60. Outside the above range, the effect of shear thinning is not appropriate, and the ink discharge performance and handwriting performance are impaired. In this connection, the viscosity of the ink is 40 to 160 m. At a high shear rate (specifically 100 rpm, 25 ° C.) generated by the ball rotation during writing. Pa. S, preferably 60 to 140 mPa.s. S range, and 160 mPa.s. If it exceeds S, ink ejection failure will occur. The appropriate range that does not cause blurring of handwriting, line breakage, ink dropout, or the like is the above-described range.
By configuring the ink with the above physical property values, it is difficult to flow in the ink containing tube due to thixotropy, but as the ink is used, it moves depending on the viscosity of the ink, and the ink is stirred at high speed in the ball containing part. Therefore, the viscosity becomes low and the ink is properly discharged.
[0012]
In addition, the thermochromic material, which is an inclusion and is a homogeneous solution of the electron-donating color-forming organic compound, the electron-accepting compound, and the color-changing temperature adjusting agent, develops and discolors at a predetermined temperature by an electron transfer reaction. Conventionally known types, for example, Japanese Patent Publication No. 51-44706, Japanese Patent Publication No. 51-44708, Japanese Patent Publication No. 52-7764, Japanese Patent Publication No. 51-35414, Japanese Patent Publication No. 1-29398, Japanese Patent Application Laid-Open No. Hei 7- 186546, etc., or described in Japanese Patent Publication No. 4-17154, JP-A-7-179777, JP-A-7-33997, etc. previously proposed by the present applicant, Thermochromic material containing a color memory temperature sensitive dye that changes color with a large hysteresis characteristic (ie, the shape of the curve plotting the color density due to temperature change causes the temperature to change from a temperature lower than the color change temperature range) When the temperature is increased and when the temperature is lowered from the higher temperature side than the discoloration temperature range, the color changes following a very different path: in the normal temperature range between the low temperature side discoloration point and the high temperature side discoloration point. It is effective to memorize and hold the aspect changed at a temperature below the low temperature side discoloration point or above the high temperature side discoloration point).
[0013]
Microencapsulation includes conventionally known interfacial polymerization methods, interfacial polycondensation methods, in situ polymerization methods, submerged curing coating methods, phase separation methods from aqueous solutions such as coacervate methods, phase separation methods from organic solvents, and dissolution. There are a dispersion cooling method, an air suspension coating method, a spray drying method, and the like, which are appropriately selected according to use. Examples of the microcapsule pigment 5 effective in the present invention include those in which an inclusion is coated with a wall film 51, as illustrated in FIGS. 1 to 5 and having a recess 52. This A single system or a mixed system of these shapes is effective. Apart from this, it may be in the form of a solid solution. The surface of the microcapsule can be provided with a secondary resin film depending on the purpose to impart durability, or the surface characteristics can be modified for practical use.
As a water-based ink for ballpoint pens, in order for the ink to move smoothly through a relatively narrow gap between the ball and the ball container, the thermochromic microcapsule pigment is basically preferably mononuclear and has a small size. An encapsulation method that is easy and has a more uniform particle size is preferred.
[0014]
As a result of examining various microencapsulation methods in this respect, microcapsules obtained by a phase separation method from an aqueous solution such as a coacervate method are crosslinked in an aqueous medium because of the use of a hydrophilic resin as an encapsulating material. Since the treated membrane itself has water swellability, the thickness of the membrane occupying the particle diameter is large, which is disadvantageous for producing an effective handwriting concentration. In addition, as an encapsulation method by an in situ method from an aqueous phase, for example, there is a method of reacting a urea-formalin initial condensate with a catalyst to form a film from the outside of the inclusion, but the disadvantage of this encapsulation method is This is because the aggregated particles are likely to be generated with probability. Aggregates formed during the reaction are mixed in the ink without being re-dissociated, and eventually trapped cumulatively in the space between the ball and the ball housing portion, which tends to cause poor writing. Spray drying or other encapsulation methods tend to cause similar problems.
[0015]
As a result of studying the most preferable encapsulation method satisfying the above-mentioned performance, the present inventor has basically reacted at the interface between the aqueous phase and the oil phase to form the membrane wall, and the encapsulation method by the interfacial polycondensation method However, since the particle distribution is narrow and aggregation does not occur, there is an advantage that the particle size set by emulsification can be easily maintained even after the capsule is finished.
Furthermore, the external shape of the capsule obtained by the method has at least one depression (concave portion), and has an overall hemispherical flat appearance.
[0016]
Such a special shape exhibits the following advantages when used as a water-based ballpoint pen ink. For one thing, the pressure at the time of writing is deformed by itself, and the pressure can be relieved, and the capsule breakage / deterioration can be remarkably reduced. When the difference from the diameter is 20 μm, that is, when one side passes through a gap of 10 μm, it becomes difficult to discharge the true spherical microcapsule pigment if the diameter exceeds 10 μm.
The hemispherical flat-shaped microcapsule pigment preferably used in the present invention has good dischargeability from the gap even if the major axis direction is approximately 15 μm when the minor axis direction is 5 μm. It is considered that the capsule pigment is discharged while being oriented along the streamline direction of the ink flow direction. Actually, the average particle size is made fine so that the particle size is set so that the narrowest gap between the ball and the ball housing portion can be more easily passed. In such a case, however, the capsule having a flat shape is a series of particles. This has a great advantage with regard to the ejection of capsule-containing inks having a distribution.
[0017]
In the ink of the present invention, not only a microcapsule pigment having a single thermochromic point, but also a pigment having a plurality of discoloration points, a general non-thermochromic dye, a pigment, etc. are used in order to diversify the change. Can be used together.
[0018]
As the shear thinning substance, a substance substantially soluble in water is effective, and xanthan gum, welan gum, and succinoglycan whose constituent monosaccharide is an organic acid-modified heteropolysaccharide of glucose and galactose (average molecular weight of about 100 to 100). 8 million), guar gum, locust bean gum and its derivatives, hydroxyethyl cellulose, alginic acid alkyl esters, polymers having a molecular weight of 100,000 to 150,000 based on alkyl esters of methacrylic acid, glycomannan, seaweeds such as agar and carrageenan More extracted carbohydrates having gelling ability, benzylidene sorbitol and benzylidene xylitol or their derivatives, cross-linkable acrylic acid polymers and the like can be exemplified, and can be used alone or in combination. In particular, xanthan gum and succinoglycan are preferable because their physical property values are stable even when stored for a long period of time.
[0019]
Since the aqueous ball ink containing the thermochromic microcapsule pigment of the present invention has a high content of the pigment as a colorant, the viscosity is already considerable only in the state of the vehicle component not containing the microcapsule pigment and the shear thinning resin. high. For this reason, the blending amount of the shear-thinning resin cannot be increased unlike an ink using a general dye / pigment. That is, the range of 0.1 to 0.5% by weight in the ink composition is preferable. The most preferred range is 0.10 to 0.30% by weight.
[0020]
Examples of water-soluble organic solvents include ethylene glycol, diethylene glycol, triethylene glycol, 1,3-propanediol, propylene glycol, butylene glycol, dipropylene glycol, thiodiethylene glycol, sorbitol, glycerin, polyethylene glycol and other polyhydric alcohols, ethylene glycol Monomethyl ether, diethylene glycol monomethyl ether, etc., triethanolamine, pyrrolidone, N-methyl-2-pyrrolidone, dimethylformamide, urea, ethylene urea, thiourea and other wetting agents, other water retention agents, etc. Can be used. These are selected according to the purpose of suppressing drying of the ink at the writing tip, imparting water resistance to the handwriting, or dissolving aid for the dye, and are used in the range of 5 to 35% by weight in the ink composition. Water is used as the main solvent.
[0021]
In addition, various surface active agents for improving the fluidity of ink and stabilizing the dispersion in aqueous media, polyvinylpyrrolidone, polyvinyl alcohol, water-soluble acrylic resin, arabic rubber for the purpose of preventing handwriting bleeding and pigment protective colloids A water-soluble resin such as a lubricant, a humectant, a preservative such as sodium benzoate and sodium dehydroacetate, a rust preventive such as benzotriazole, an antifoaming agent, and the like can be added as necessary.
[0022]
The specific gravity of the microcapsule pigment is generally in the range of 0.95 to 1.05 at 25 ° C., but the storage stability can be enhanced by appropriately adjusting the specific gravity in combination with the vehicle. Usually, it is preferable to adjust the specific gravity difference between the microcapsule pigment and the vehicle within a range of 0.05.
There are two methods for adjusting the specific gravity, one is a method that does not affect the thermochromic function and a compound having a large specific gravity is added within a range that does not deteriorate the color change function, and the other method is a micro method. A film agent having a specific gravity greater than 1 is applied as a film agent for forming capsules.
[0023]
These methods are effective to reduce the difference to 0.05 or less when the specific gravity of the fine particles is less than 1 and the specific gravity difference from the aqueous vehicle is 0.1 or more. When the specific gravity difference is greater than 0.05 and less than 0.1, it can be adjusted by microencapsulation with a normal film agent.
[0024]
Examples of the compound having a large specific gravity include halides, for example, chlorine, bromine and iodine as the halogen atom, preferably bromine having a large specific gravity increasing effect and having various kinds of compounds. Specifically, hexabromobenzene, hexachlorobenzene, brominated phenyl methacrylate, brominated phenyl acrylate, tetrachlorobisphenol A, decabromobiphenol ether, dibromostearate, chlorinated paraffin, tris (2, 3- Dihalopropyl) phosphate, dibromophenol, 2,3-dibromopropanol, tetrachlorophthalic anhydride, perchloropentacyclodecane, tetrabromobutane, chlorinated polyphenyl, and other halogen-substituted aromatics And aliphatic compounds.
[0025]
As the film agent used for adjusting the specific gravity, a main agent and a curing agent or a catalyst which form a film agent without inhibiting the discoloration function of the inclusion and increase the specific gravity are used.
[0026]
When the specific gravity difference between the thermochromic composition and the inclusion is relatively large (specific gravity difference> 0.1) and it is difficult to adjust the specific gravity with a normal film agent, a halogen-substituted resin is preferable, for example, bromination Epoxy resins, chlorinated epoxy resins, brominated unsaturated polyester resins, brominated acrylic resins, brominated urethane resins, brominated styrene, vinyl chloride, vinylidene chloride and other halogen-containing resins that are usually used as flame retardant resins Can be mentioned. One or more of these resins are appropriately used as a film agent for microcapsules in combination with a curing agent or a catalyst.
[0027]
When the specific gravity of the thermochromic composition is approximately 1 and is close to the specific gravity of the aqueous vehicle, the addition of the halogen-containing product or the halogen-containing resin is not necessarily required, and fine adjustment with a normal film agent may be used.
[0028]
Next, the drawings relating to the ballpoint pen according to the second invention will be described (see FIGS. 6 to 11). The ball-point pen 1 applied to the present invention is a ball-point pen 1 that includes a tip that rotatably holds a ball 2 and is configured to be able to write by drawing out ink stored in an ink storage unit 4. (A) A homogeneous solution containing an electron-donating organic compound, an electron-accepting compound, and a reaction medium for adjusting the color change temperature as an essential component is coated with a wall film having depressions on at least a part of the outer surface, and the particle distribution is 0.5 μm. Occupies 95 vol% or more in the range of ~ 20μm Thermochromic microcapsule pigment, (b) Filled with thermochromic water-based ballpoint pen ink 6 consisting of an aqueous medium containing shear thinning substance, water and water-soluble organic solvent, wherein the microcapsule pigment is dispersed in the aqueous medium Being done.
Furthermore, an ink follower is disposed in contact with the rear end portion of the thermochromic ballpoint pen ink 6 in the accommodated state in the ink accommodating portion 4, and the ball accommodating portion 3 for holding the ball 2 rotatably. The difference between the inner diameter A of the ball 2 and the outer diameter B of the ball 2 is 10 to 60 μm, and the difference between the inner diameter A and the ball outer diameter B of the ball housing portion 3 that rotatably holds the ball 2 is 10 to 60 μm. And the ball 1 is provided with a space C that can move 20 to 100 μm in the axial direction, and the thermochromic water-based ballpoint pen ink 6 is ,heat Discoloration microcapsule pigment 15 to 45% by weight (solid content), shear thinning resin 0.1 to 0.5% by weight, water-soluble organic solvent 5 to 35% by weight, the balance is composed of water, Viscosity is 40 to 160 m. Pa. It is in the range of s (value at a rotational speed of 100 rpm in the EM type rotational viscometer), and satisfies the shear thinning index of 0.1 to 0.6.
In the above, when the difference between the inner diameter A of the ink containing portion 3 and the outer diameter B of the ball is set to 10 to 60 μm, more preferably 15 to 40 μm, a smooth writing feeling is satisfied and a handwriting with an appropriate concentration is given. Further, by setting the length of the ball 2 that can move in the axial direction to 20 to 100 μm, preferably 40 to 80 μm, the discharge property for satisfying an appropriate handwriting density is satisfied.
[0029]
As for the structure of the writing tip portion as described above, a general-purpose mechanism has been effective from the past, and a mechanism in which the ink containing portion 4 is integrally formed by pressing and deforming the vicinity of the tip end of a metal pipe inward from the outer surface. (See FIGS. 6 to 7) Or, a mechanism for forming the ink containing portion 4 by cutting with a metal material drill or the like and arranging the ball receiving seat 33, the center hole 31, and the radial outlet groove 32 (FIG. 8). To FIG. 9), or a mechanism (FIG. 10) that urges the ball forward by a spring body can be applied.
[0030]
The ink follower 7 is for preventing ink leakage or the like when the ballpoint pen 1 is faced upward or sideways, and is immiscible and insoluble with the ink, and is conventionally known as a viscoelastic body such as polybutene, A gel-like backflow preventer based on silicone oil or the like is particularly effective, but a conventionally known solid plug or the like may be used.
[0031]
A ball 2 having a diameter of 0.3 to 1.2 mm, such as cemented carbide, stainless steel, ruby, or ceramic, can be applied.
[0032]
DETAILED DESCRIPTION OF THE INVENTION
Examples of the present invention are described below. In addition, the part in the compounding of the examples is part by weight.
Example 1
A method for preparing the thermochromic microcapsule pigment used in this example will be described.
A thermochromic composition composed of 6 parts of 6- (ethylisobutylamino) benzofluorane, 6 parts of bisphenol A, 30 parts of cetyl alcohol and 20 parts of stearyl caprate and 1 part of tinuvin 326 as a light resistance-imparting agent, and then as a film material 15 parts of epoxy resin having an epoxy equivalent of 190 obtained by the reaction of bisphenol A and epichlorohydrin was uniformly heated and dissolved, and the average particle size was adjusted to 5 μm in 100 parts of an aqueous protective colloid medium previously heated at 70 ° C. The mixture was emulsified with a homomixer. Subsequently, 5 parts of an aliphatic modified polyamine curing agent was added and stirring was continued at 90 ° C. for 5 hours to obtain a microcapsule dispersion by an interfacial polymerization method. Centrifugation was performed for the purpose of concentrating the microcapsules to obtain 100 parts of a slurry-like water-containing cake. It was 38% when the moisture content of the capsule slurry was measured.
[0033]
Further, a centrifugal sedimentation type automatic particle size distribution measuring device (manufactured by Horiba, Ltd., CAPA-300) was used to measure the particle size distribution. When the particle diameter is D, the relationship between the particle diameter and the occupied volume% [shown in ()] is as follows.

In the above, the cumulative total of 0.5 μm ≦ D ≦ 20 μm is 98%, and the average particle size is 4.2 μm.
[0034]
When the obtained microcapsule was observed with a microscope, it was confirmed to be a hemispherical flat capsule having a concave portion. The flatness increased as the particle size increased. The thermochromic microcapsule pigment had a magenta color at 27 ° C. or lower, colorless at 32 ° C. or higher, and a transition region of discoloration between both temperatures.
[0035]
An aqueous ballpoint pen ink was prepared using the obtained microcapsule slurry as a colorant. The compounding example is shown below.

[0036]
The viscosity of the ink was measured at 25 ° C. with an EMD type viscometer. Pa. s, 84 m. Pa. The value of s was shown, and the shear thinning index n0.48.
Note that Nopco SW-WET-366 is a nonionic permeability imparting agent manufactured by San Nopco, Nopco 8034 is a modified silicone antifoaming agent, and Proxel XL-2 is an I.D. C. It is a benzothiazoline preservative made by I company.
[0037]
Ballpoint pen production
A cutting die using 0.8 mm stainless steel balls, with a difference S (A−B) = 20 μm between the inner diameter of the ball housing portion and the outer diameter of the ball = 20 μm, and an axially movable space C = 70 μm. A ballpoint pen tip was used. 0.8 g of the thermochromic ink was sucked and filled into a polypropylene pipe having an inner diameter of 3.3 mm, and connected to the ballpoint pen tip through a resin holder.
Next, from the tail of the polypropylene pipe, a polybutene-based ink follower (liquid stopper) having a viscoelasticity is filled, and after the exterior pen shaft, cap, cap and tail plug are assembled, centrifugal treatment is performed to remove air. Thus, a thermochromic water-based ballpoint pen was obtained.
When writing on the report paper with the thermochromic water-based ballpoint pen, good pink density and handwriting were obtained from the writing. Subsequently, writing was continued, but all of the ink could be consumed without any undesired phenomena such as ink dripping, significant line cracking, blurring, and handwriting skipping. Furthermore, in order to confirm the destruction and deterioration of the microcapsule due to the writing pressure at the time of writing, the ink on the written paper surface was collected, and the appearance of the capsule was examined with a microscope. No capsule breakage was observed. .
[0038]
As a result of testing the thermochromic property of the handwriting, it showed a magenta color at 27 ° C. or lower and a colorless thermochromic property at 32 ° C. or higher. The same thermochromic property as that of the microcapsule slurry used as a raw material for inking was confirmed, and it was confirmed that the thermochromic function was maintained even after writing.
Separately, a ballpoint pen of the same specification was prepared, and after standing in an upright, inverted, and horizontal state for 30 days in a constant temperature room at 50 ° C., a written test was performed. As a result, similar to the initial test, good results were obtained. Obtained.
[0039]
Example 2
2- (4-Diethylamino-2-ethoxyphenyl) -3- (1-ethyl-2-methylindol-3-yl) -4-azaphthalide, 2.5 parts, 2,2-bis (4-hydroxyphenyl) hexa A thermochromic composition comprising 5 parts of fluoropropane and 50 parts of neopentyl stearate, 1 part of tinuvin 326 as a light fastness imparting agent, and then 15 parts of an oligomer obtained by reacting aromatic diisocyanate and glycol as a film material. The solution was heated and dissolved together with 30 parts of a co-solvent and emulsified with a homomixer so as to have an average particle diameter of 2.5 μm in 100 parts of an aqueous protective colloid medium which had been heated at 70 ° C. in advance.
Subsequently, 5 parts of an aliphatic modified polyamine curing agent was added and stirring was continued at 90 ° C. for 5 hours to evaporate and remove the co-solvent to obtain a microcapsule dispersion by an interfacial polymerization method. Centrifugation was performed for the purpose of concentrating the microcapsules to obtain 98 parts of a slurry-like water-containing cake. It was 32% when the water content of the capsule slurry was measured.
[0040]
Further, a centrifugal sedimentation type automatic particle size distribution measuring device (manufactured by Horiba, Ltd., CAPA-300) was used to measure the particle size distribution. When the particle diameter is D, the relationship between the particle diameter and the occupied volume% [shown in ()] is as follows.

The cumulative total was 97% of the above 0.5 μm ≦ D ≦ 20 μm, and the average particle size was 2.7 μm.
[0041]
When the obtained microcapsule was observed with a microscope, it was confirmed to be a hemispherical flat capsule having a concave portion (see FIGS. 2 to 5). The flatness increased as the particle size increased. The thermochromic microcapsule pigment had a thermochromic property of blue at 14 ° C. or lower and colorless at 32 ° C. or higher, having a wide hysteresis characteristic between both temperatures, and capable of the two-state color. An aqueous ballpoint pen ink was prepared using the obtained microcapsule slurry as a colorant. The compounding example is shown below.

[0042]
As a result of measuring the viscosity of the ink with an EMD viscometer at 25 ° C., 1306 m. Pa. s, 100 m and 122 m. Pa. s, Shear thinning index n0.49.
[0043]
Ballpoint pen production
A cutting die using 0.5 mm stainless steel balls, with a difference S (A−B) = 20 μm between the inner diameter of the ball housing portion and the outer diameter of the ball = 20 μm, and a space C = 40 μm movable in the axial direction. A ballpoint pen tip was used. 0.8 g of the thermochromic ink was sucked and filled into a polypropylene pipe having an inner diameter of 3.3 mm, and connected to the ballpoint pen tip through a resin holder. Next, from the tail of the polypropylene pipe, a polybutene-based ink follower (liquid stopper) having a viscoelasticity is filled, and after the exterior pen shaft, cap, cap and tail plug are assembled, centrifugal treatment is performed to remove air. Thus, a thermochromic water-based ballpoint pen was obtained.
When writing on a report sheet using the thermochromic water-based ballpoint pen, good pink density and handwriting were obtained from the writing. Subsequently, writing was continued, but all of the ink could be consumed without any undesired phenomena such as ink dripping, significant line cracking, blurring, and handwriting skipping.
[0044]
Furthermore, in order to confirm the destruction and deterioration of the microcapsule due to the writing pressure at the time of writing, the ink on the written paper surface was collected, and the appearance of the capsule was examined with a microscope. No capsule breakage was observed. .
As a result of testing the thermal discoloration of the handwriting, it was blue at 14 ° C. or less, colorless at 32 ° C. or more, and the same discoloration as that of the capsule slurry used as a raw material for the inking also with respect to hysteresis characteristics between both temperatures. Showed sex.
[0045]
Example 3
Using the same capsule slurry (water content 38%) as in Example 1, the type of shear-thinning resin in the ink formulation was changed to succinoglucan, and the amount added was changed to an appropriate viscosity.
[0046]
The specifications of the ballpoint pen followed the same method as in Example 1. Examples of ink blending are shown below.

[0047]
Example 4
Using the same capsule slurry (water content 38%) as in Example 1, the type of shear thinning resin in the ink formulation was changed to a cross-linked acrylic water-soluble resin (manufactured by Sumitomo Seika Co., Ltd., ACPEC HV501) and its weight was also changed. changed.
[0053]
The specifications of the ballpoint pen followed the same method as in Example 1. Ink mixing examples are shown below.

[0048]
Example 5
Using the same ink as in Example 2, the ballpoint pen tip portion was changed from a cutting type to a pipe pressing deformation type (FIGS. 6 to 7) method to produce a ballpoint pen. In other words, a 0.7 mm stainless steel ball is used, and the ball housing portion has a difference between the pipe inner diameter and the ball outer diameter S (A−B) = 30 μm, and an axially movable space C = 25 μm. A chip was used.
0.8 g of the thermochromic ballpoint pen ink was sucked and filled into a polypropylene tube having an inner diameter of 3.3 mm, and connected to the ballpoint chip through a resin holder. Next, from the tail of the polypropylene tube, a polybutene-based ink follower (liquid stopper) having a viscoelasticity is filled, and after the exterior pen shaft, cap, cap, and tail plug are assembled, centrifugal treatment is performed to remove air. Thus, a thermochromic water-based ballpoint pen was obtained.
[0049]
When writing on a report paper using the thermochromic water-based ballpoint pen, good pink density and handwriting were obtained from the writing. Subsequently, writing was continued, but all of the ink could be consumed without any undesired phenomena such as ink dripping, significant line cracking, blurring, and handwriting skipping. Furthermore, in order to confirm the destruction and deterioration of the microcapsule due to the writing pressure at the time of writing, the ink on the written paper surface was collected, and the appearance of the capsule was examined with a microscope. No capsule breakage was observed. .
As a result of testing the thermal discoloration of the handwriting, it was blue at 14 ° C. or less, colorless at 32 ° C. or more, and the same discoloration as that of the capsule slurry used as a raw material for the inking also with respect to hysteresis characteristics between both temperatures. Showed sex.
[0050]
Example 6
Using the microcapsule slurry of Example 2, a general fluorescent pigment (pink) was blended during ink blending to prepare an ink having color-to-color discoloration. The fluorescent pigment SW-27 is a pink fluorescent pigment manufactured by Sinloihi.
Examples of ink blending are shown below.

[0051]
Cutting type ball-point pen tip using a 0.5 mm stainless steel ball for the ink, and having a difference between the inner diameter of the ball receiving portion and the ball S (A−B) = 20 μm and an axially movable space C = 40 μm. Was used at the tip.
0.8 g of the thermochromic ballpoint pen ink was sucked and filled into a polypropylene tube having an inner diameter of 3.3 mm, and connected to the ballpoint chip through a resin holder. Next, from the tail of the polypropylene tube, a polybutene-based viscoelastic ink follower (liquid stopper) is filled, and after the exterior pen shaft, cap, cap, and tail plug are assembled, centrifugation is performed to remove air. Thus, a thermochromic water-based ballpoint pen was obtained.
[0052]
When I wrote it on the report paper, I got a good purple-colored handwriting. Subsequently, writing was continued, but all of the ink could be consumed without any undesired phenomena such as ink dripping, significant line cracking, blurring, and handwriting skipping. Furthermore, in order to confirm the destruction and deterioration of the microcapsule due to the writing pressure at the time of writing, the ink on the written paper surface was collected, and the appearance of the capsule was examined with a microscope. No capsule breakage was observed. .
As a result of testing the thermal discoloration of the handwriting, the color is purple at 14 ° C. or lower, fluorescent pink at 32 ° C. or higher, and the hysteresis characteristics between the two temperatures are the same as the discoloration of the capsule slurry used as the raw material for the inking. It showed discoloration.
[0053]
Example 7
2- (2-chloroanilino) -6-dibutylfluorane 3 parts, 1,1-hexylidene bisphenol 8 parts, n-butyl stearate 30 parts, n-butyl palmitate 20 parts, tinuvin 328 (manufactured by Ciba Geigy, UV Absorbent) Add 2 parts of thermochromic composition, 20 parts of phenol novolac epoxy resin, 50 parts of co-solvent, and heat the inclusion solution at 70 ° C. to a homomixer in an aqueous protective colloid resin medium. And emulsified and dispersed. The particle size at the time of emulsification was adjusted while adjusting the rotation speed of the homomixer so that the average was 10 μm. Then, a water-soluble diamine compound was added as a curing agent, and stirring was continued at 90 ° C. for 8 hours to complete encapsulation.
After the reaction, the capsule dispersion was diluted with twice the amount of water, filtered through a 625 mesh stainless steel mesh, and 105 g of microcapsules were isolated as a water-containing cake by centrifugation. The cake had a water content of 38%.
[0054]
The particle size distribution of the microcapsules was measured in the same manner as in Example 1.

The above was a cumulative 97% and an average volume average particle size of 12 μm at 0.5 μm ≦ D ≦ 20 μm.
[0055]
When the obtained microcapsule was observed with a microscope, it was confirmed to be a hemispherical flat capsule having a concave portion.
[0056]
The thermochromic property of the microcapsule pigment was black at 12 ° C. or lower and colorless at 17 ° C. or higher. A transition region of discoloration was shown between the two temperatures. Using the obtained microcapsule pigment, a ballpoint pen was produced with the same ink formulation as in Example 1 and the specifications of the ballpoint pen. When writing on the report paper, good ink ejection was observed from writing out, and the handwriting density was also reasonable. As a result of continuously writing round loops, all the filled ink could be consumed. The handwriting was left in a thermostatic bath at 50 ° C. for 10 days, and then its discoloration was examined. As a result, the thermochromic property was black at 12 ° C. or less and colorless at 17 ° C., and there was no deterioration in the discoloring function of the handwriting including the transition region.
[0057]
Comparative Example 1
In order to change only the particle distribution of Example 1, a ballpoint pen was produced in exactly the same manner as in Example 1 except that the average particle size during emulsification was set to 15 μm and microencapsulation was performed. The particle size distribution of the obtained microcapsule slurry was as follows.

The above was a cumulative of 81% and an average particle size of 16 μm at 0.5 μm ≦ D ≦ 20 μm.
[0058]
When a writing test was performed, the ink was faint after writing and the ink started to be ejected after a while, but the density was extremely low and the handwriting density was somewhat unsatisfactory. When 0.1g of ink was consumed, it became faint, so when the ballpoint pen was disassembled and the ink in the ball container, especially the ink in the vicinity of the ball, was observed with a microscope, 25-30μm mononuclear but large particles were densely packed. It was.
[0059]
Comparative Example 2
The same microcapsule slurry as in Example 1 was used, and the amount of shear thinning resin in the ink formulation was increased. The ballpoint pen specifications were produced by the same method as in Example 1. Examples of ink blending are shown below.

[0060]
When a writing test was performed using the thermochromic water-based ballpoint pen obtained as described above, no ink was ejected from the writing, and there was no change even if writing was continued for a while. When the ink viscosity was measured, the viscosity was high as shown in the following table, which is considered to be due to insufficient viscosity reduction at the time of shearing, which is characteristic of aqueous balls.
[0061]
Tables 1 to 6 and Comparative Examples 1 and 2 show the solid content, average particle diameter, ink viscosity, shear thinning viscosity, ball diameter, clearance, and evaluation in the writing test.
[Table 1]

[0062]
【The invention's effect】
The present invention is a shear-thinning thermochromic ink in which a thermochromic microcapsule pigment is dispersed and a ballpoint pen using the same, satisfying a smooth writing feeling and maintaining a uniform and stable thermochromic handwriting. It is a new handy writing material that can be given. As a method for applying thermochromic materials to writing materials, solid writing materials in which thermochromic microcapsule pigments are dispersed in an excipient such as wax have been disclosed. The width of the handwriting cannot be formed continuously, the writing feeling is not smooth, and even if it has applicability to the art material field, it does not satisfy the practicality as a writing instrument.
[0063]
The ballpoint pen of the present invention has utility in many fields.
Specifically, application uses of the aqueous thermochromic ballpoint pen of the present invention are exemplified.
(1) Enter a secret message or pattern on a New Year's card, Christmas card, greeting card, etc. with a thermochromic ballpoint pen, or combine a variety of cards with a general ballpoint pen or printed pattern so that the pattern changes. Can be created.
(2) Similarly, when creating a memo that requires secrecy, it can be filled in with the ballpoint pen of the present invention. If you apply a thermochromic material that develops color only when it is cooled, such as at a color change point of 10 ° C, it will be in a decolored state at room temperature. There are advantages.
(3) The thermochromic water-based ballpoint pen of the present invention exhibits a special effect when used for learning. That is, for example, if you use a ballpoint pen that has a large hysteresis characteristic for discoloration and use it for problem collection, test, drill, English translation into Japanese, enter the answer and supplementary matters once in the color state of thermochromic ink After learning, if you want to review again or check your memory, once you have erased all the entries by applying heat, you can start working on the problem again in a completely reset state. Since this operation can be repeated any number of times, it is advantageous as a writing instrument for the learning field as an unprecedented useful material.
(4) It can also be used in normal writing instrument usage. In other words, if you use a thermochromic ink that has a discoloration temperature that maintains its colored state at room temperature, such as 33 ° C discoloration ink, you can enjoy the colorful color change of the handwriting after writing like a normal writing instrument. You can also. In such a case, in addition to the one that changes from color to colorless, use a dichroic change that changes from color to color, or use a thermochromic capsule with a different color change temperature and a different color, and then breathe or warm by hand. It is possible to enjoy various color changes according to temperature changes.
[Brief description of the drawings]
FIG. 1 is a schematic explanatory diagram of an outer shape of an example of a microcapsule pigment. (A) shows the appearance, and (B) shows the cross-sectional state.
FIG. 2 is a schematic explanatory view of the outer shape of another example of a microcapsule pigment. (A) shows the appearance, and (B) shows the cross-sectional state.
FIG. 3 is a schematic explanatory view of the outer shape of another example of a microcapsule pigment. (A) shows the appearance, and (B) shows the cross-sectional state.
FIG. 4 is a schematic explanatory view of the outer shape of another example of a microcapsule pigment. (A) shows the appearance, and (B) shows the cross-sectional state.
FIG. 5 is a schematic explanatory view of the outer shape of another example of a microcapsule pigment. (A) shows the appearance, and (B) shows the cross-sectional state.
FIG. 6 is an explanatory view of a longitudinal section of an embodiment of a tip portion of the ballpoint pen of the present invention.
7 is a cross-sectional view taken along line XX in FIG.
FIG. 8 is a longitudinal cross-sectional explanatory view of another example of the tip portion of the ballpoint pen of the present invention.
9 is a cross-sectional view taken along line XX in FIG.
FIG. 10 is an explanatory view of a longitudinal section of another example of the tip portion of the ballpoint pen of the present invention.
FIG. 11 is an explanatory view of a longitudinal section of an embodiment of the ballpoint pen of the present invention.
[Explanation of symbols]
1 Ballpoint pen
2 balls
3 Ball housing
31 Center hole
32 Lead groove
33 Ball seat
4 Ink storage part
5 Microcapsule pigment
51 Membrane
52 Dimple
53 Thermochromic composition
6 Thermochromic water-based ballpoint pen ink
7 Ink follower
A Inside diameter
B outer diameter
C space

Claims (8)

As an essential component, (a) a homogeneous solution containing an electron-donating organic compound, an electron-accepting compound, and a reaction medium for adjusting the color change temperature as an essential component is coated with a wall film having a depression on at least a part of the outer surface. The microcapsule pigment comprising an aqueous medium containing a thermochromic microcapsule pigment having a particle distribution of 95% by volume or more in a range of 0.5 μm to 20 μm, (b) a shear-thinning substance, water and a water-soluble organic solvent. Is a thermochromic water-based ballpoint pen ink dispersed in the aqueous medium. The thermochromic water-based ballpoint pen ink according to claim 1, wherein the wall film of the thermochromic microcapsule pigment is formed by interfacial polymerization or interfacial polycondensation. Thermochromic microcapsule pigment 15 to 45% by weight (solid content), shear thinning resin 0.1 to 0.5% by weight, water-soluble organic solvent 5 to 35% by weight, the balance consisting of water, the viscosity is 40-160 m. Pa. The thermochromic water-based ballpoint pen ink according to claim 1 or 2, which is in a range of s (value at a rotational speed of 100 rpm in an EM type rotational viscometer) and satisfies a shear thinning index of 0.1 to 0.6. A ballpoint pen having a tip that rotatably holds a ball and configured to be able to write by drawing out the ink contained in the ink containing portion. And a homogeneous solution having a reaction medium for adjusting the color change temperature as an essential component is coated with a wall film having depressions on at least a part of the outer surface, and the particle distribution is 95% by volume or more in the range of 0.5 μm to 20 μm. It consists of a thermochromic microcapsule pigment, (b) an aqueous medium containing a shear thinning substance, water and a water-soluble organic solvent, and the microcapsule pigment is filled with a thermochromic aqueous ballpoint pen ink dispersed in the aqueous medium. A ballpoint pen characterized by being made. The ballpoint pen according to claim 4, wherein an ink follower is disposed in contact with a rear end portion of the thermochromic ballpoint pen ink in a contained state in the ink containing portion. 6. The ballpoint pen according to claim 4 or 5, wherein a difference between an inner diameter of the ball housing portion that rotatably holds the ball and an outer diameter of the ball is 10 to 60 [mu] m. 7. The ballpoint pen according to claim 6, wherein a difference between the inner diameter and the outer diameter of the ball housing portion for holding the ball rotatably is 10 to 60 [mu] m, and the ball has a space in which the ball can move 20 to 100 [mu] m in the axial direction. The thermochromic water-based ballpoint pen ink contains 15 to 45% by weight (solid content) of thermochromic microcapsule pigment, 0.1 to 0.5% by weight of shear thinning resin, and 5 to 35% by weight of a water-soluble organic solvent. The balance is composed of water, and the viscosity is 40 to 160 m. Pa. The ballpoint pen according to claim 4, which is in a range of s (value at a rotational speed of 100 rpm in an EM type rotational viscometer) and satisfies a shear thinning index of 0.1 to 0.6.

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