JP3938243B2 - Manufacturing method of fired colored pencil lead - Google Patents
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- JP3938243B2 JP3938243B2 JP09031298A JP9031298A JP3938243B2 JP 3938243 B2 JP3938243 B2 JP 3938243B2 JP 09031298 A JP09031298 A JP 09031298A JP 9031298 A JP9031298 A JP 9031298A JP 3938243 B2 JP3938243 B2 JP 3938243B2
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【０００１】
【発明の属する技術分野】
本発明は、滑らかな書き味と機械的強度、すなわち、曲げ強度、引張強度、衝撃強度等に優れると共に、十分な発色性、描線濃度を備えた焼成色鉛筆芯の製造方法に関する。
【０００２】
【従来の技術】
従来の焼成色鉛筆芯は、結合材として一種及び／又は二種以上の粘土等が用いられ、これに窒化硼素等の体質材、更に必要に応じて耐熱性の顔料、反応促進材を添加、配合した配合組成物を混練し、この混練物を押出成形した後、熱処理を経て多孔質焼成芯体とし、この芯体の気孔中に染料および顔料から成るインキ等を充填させて製造していた。この時、色鉛筆芯の重要特性としては、機械的強度が強く、発色性が良く、筆記描線の濃度が濃いものが要求されている。
【０００３】
しかしながら、従来の焼成色鉛筆芯は、機械的強度が充分でなく、濃度および発色性においても充分なものが得られていない。また、インキを充填させて発色させるためには、用いる配合材の条件は白色もしくは淡色でなければならない。そこで、上記の要求を達成するためには、必須条件として充分な機械的強度を保持しつつ、気孔率の高い、白色の多孔質芯体を容易に得る必要がある。
【０００４】
最近において、上記各々の条件に沿う白色の多孔質芯体を得る技術が開発されているが、上記各々の条件を未だ充分満足できる白色の多孔質芯体を得られていないのが現状である。
例えば、特公昭６４−７１１３号公報には、少なくとも硼素と窒素からなる化合物を骨格とした多孔質焼結体と、その多孔質焼結体の気孔中に充填されているインキとから構成されている色鉛筆芯、並びに、少なくとも硼素化合物あるいは硼素化合物と硼素を含有する組成物を押出成形し、窒素あるいは窒素と水素を含有する気体と高温度で反応させて、少なくとも硼素と窒素からなる化合物を骨格とした多孔質焼結体を作製し、次にこの多孔質焼結体の気孔中にインキを充填することを特徴とする色鉛筆芯の製造方法が開示されている。
【０００５】
しかしながら、この色鉛筆芯及びその製造方法は、硼素を含んだ細線鉛芯状素材（例えば、Ｂ2Ｏ3）を少なくとも窒素あるは窒素と水素からなる雰囲気中において、高温度で熱処理を施し硼素と窒素とを反応させることにより（例えば、Ｂ2Ｏ3＋２ＮＨ3→２ＢＮ＋３Ｈ2Ｏ）、直接強固に焼結させた窒化硼素に変化させ、この反応生成した窒化硼素（ＢＮ）を細線鉛芯状素材の全体に亘つて生ぜしめるものであり、粘土、樹脂等の焼結性結合材を不要としたものであるが、上記窒素あるは窒素と水素からなる雰囲気中での熱処理による直接の窒化硼素の形成は、未だ焼結性が十分ではなく、また、十分な曲げ強度、引張強度及び衝撃強度、並びに、十分な発色性、描線濃度を備えたものではないという課題があり、また、本発明とは、その構成、作用等が相違し、技術思想が異なるものである。
【０００６】
【発明が解決しようとする課題】
本発明の目的は、上記従来技術の課題、特に、上記従来の多孔質体として最終的に窒化硼素を用いる場合の課題等を解決することであり、格段に優れた機械的強度及び優れた発色性、滑らかな書き味を有する焼成色鉛筆芯の製造方法を提供することにある。
【０００７】
【課題を解決するための手段】
本発明者は、前記課題を解決するために鋭意研究を行った結果、少なくとも体質材と賦形材とを含む配合組成物を成形処理等した黒色の焼成芯体を特定の混合ガスの接触（雰囲気）下で特定温度範囲となる高温で接触させることにより、黒色の焼成芯体中の炭素を窒化硼素に置換することにより、白色多孔質芯体を得ることを見いだし、本発明を完成するに至ったのである。
すなわち、本発明の焼成色鉛筆芯の製造方法は、少なくとも黒鉛若しくは窒化硼素の体質材と賦形材とを含む配合組成物を混練、押出成形、高温焼成してなる黒色の焼成芯体を、酸素含有硼素蒸気と窒素含有ガスとの混合ガスに接触させ、該混合ガスの接触下で１４００〜２２００℃の温度に加熱し、前記黒色の焼成芯体中の炭素を窒化硼素に置換させた白色の多孔質芯体を作製し、該多孔質芯体の気孔内にインキを充填させてなることを特徴とする。
前記製造方法において、体質材の一部又は全量に焼結性の窒化硼素を用いることが好ましい。
なお、本発明で規定する「焼結性の窒化硼素」とは、高温（１４００℃以上）で焼結する窒化硼素をいい、具体的には、粒成長を抑えた低結晶性の窒化硼素で、粒子同士の結合力の優れた平均粒子径が０．１〜０．５μｍ程度の窒化硼素粉末をいうものである。
【０００８】
【発明の実施の形態】
以下に、本発明の実施の形態を詳しく説明する。
本発明の焼成色鉛筆芯の製造方法は、少なくとも黒鉛若しくは窒化硼素の体質材と賦形材とを含む配合組成物を混練、押出成形、高温焼成してなる黒色の焼成芯体を、酸素含有硼素蒸気と窒素含有ガスとの混合ガスに接触させ、該混合ガスの接触下で１４００〜２２００℃の温度に加熱し、前記黒色の焼成芯体中の炭素を窒化硼素に置換させた白色の多孔質芯体を作製し、該多孔質芯体の気孔内にインキを充填させてなることを特徴とするものである。
【０００９】
本発明において、まず黒色の焼成芯体の製造には、少なくとも体質材と賦形材とを含む配合組成物を原料とする。
体質材としては、例えば、従来焼成芯に用いられている黒鉛、窒化硼素等が使用でき、また、焼結性（焼結型）の窒化硼素は高温で焼結するものであれば、特に限定されるものでなく使用可能である。
具体的には、立方晶窒化硼素、六方晶窒化硼素等が使用可能で、当然、これらの黒鉛、窒化硼素、焼結型の窒化硼素等の混合物も使用可能である。
体質材の一部又は全量に焼結性の窒化硼素を使用することにより、滑らかな書き味を損なうことなく、更に曲げ強度等の機械的強度に優れた焼成色鉛筆芯が得られることとなる。
【００１０】
賦形材としては、有機質の賦形材が挙げられ、例えば、塩化ビニル樹脂、塩素化塩化ビニル樹脂、ポリビニルアルコールなどの熱可塑性樹脂、フラン樹脂、フェノール樹脂、エポキシ樹脂などの熱硬化性樹脂、リグニン、セルロース、トラガントガムなどの天然高分子物質、石油アスファルト、コールタールピッチ、ナフサ分解ピッチ、合成樹脂の乾留ピッチなどのピッチ類等いずれも使用可能で、当然これら数種類の混合物も使用できる。
【００１１】
更に、高せん断力を加えて行う混練時の特性向上及び押出成形の特性向上の目的で、水（精製水）、ジオクチルフタレート（ＤＯＰ）、ジブチルフタレート（ＤＢＰ）、リン酸トリクレジル（ＴＣＰ）、アジピン酸ジオクチル（ＤＯＡ）、プロピレンカーボナート、アルコール類、ケトン類、エステル類など有機質の賦形材の可塑剤又は溶剤の一種又は二種以上を、必要に応じて配合しても良い。
【００１２】
これらの配合組成物をヘンシェルミキサー、加圧ニーダー、二本ロール等で十分混練した後、押出成形機により細線状等に押出成形し、次いで、窒素雰囲気中又はアルゴンガスなどの不活性ガス雰囲気中等の非酸化性雰囲気中で焼成することにより、体質材は均一に分散し、充分に高配向し、有機質の賦形材が炭化され炭素をバインダーとする黒色の焼成芯体が得られる。
【００１３】
本発明の重要なポイントは、通常、上記方法で得られる焼成芯体は、バインダー炭素のために、たとえ白色の体質材を使用しても黒色の芯体になってしまうものであるが、黒鉛あるいはバインダー炭素を酸素含有硼素蒸気と窒素含有ガスとの混合ガスの接触下（雰囲気中）で加熱処理して、窒化硼素に置換することによって白色の多孔質芯体を得ることができ、該白色多孔質芯体の気孔内にインキを充填して着色することにより焼成色鉛筆芯体を得ることができるものである。
本発明の基本的な反応は、黒鉛あるいはバインダー炭素（Ｃ）によるＢ2Ｏ2、Ｂ2Ｏ3等の酸素含有硼素蒸気の還元反応と、雰囲気中の窒素により窒化硼素を生じさせる反応である。
この反応は、黒鉛あるいはバインダー炭素の表面で生じるため、黒鉛あるいはバインダー炭素の層が窒化硼素の層に置換されながら進行する。このようにして、使用した炭素質焼成芯の形状と同一形状の窒化硼素質の芯の製造が可能となる。
【００１４】
本発明において、硼素源としての酸素含有硼素蒸気は、例えば、Ｂ2Ｏ2、Ｂ2Ｏ3等の酸化硼素、ＢｘＮｙＯｚ（ｘ，ｙ，ｚは、任意の正の整数である、以下同様）構造の硼素化合物、Ｈ3Ｂ０3，ＨＢ０2，Ｈ2Ｂ4０7などのＨｘＢｙＯｚ構造の硼酸、これらの硼酸と炭素の混合物などを加熱することにより容易に得ることができる。
また、窒素含有ガスは、最も安価なＮ2ガス、あるいはＮＨ3ガス、高温でＮ2と炭素材料との反応で生成するシアンガス等が利用できる。
なお、本発明で規定する「酸素含有硼素蒸気と窒素含有ガスとの混合ガス」とは、酸素含有硼素蒸気と窒素含有ガスとの混合ガスをいい、上記黒色の焼成芯体における黒鉛あるいはバインダー炭素（Ｃ）を窒化硼素に置換するための混合ガスであれば、その混合割合は特に限定されるものではない。
【００１５】
本発明において、上記混合ガスの接触下（雰囲気中）での反応温度は、高温ほど反応が進行しやすく、少なくとも、１４００℃以上、１４００〜２２００℃の範囲で行う必要がある。
反応温度が１４００℃未満であると、反応の進行が遅くなると共に、白色の多孔質芯体を得ることができず、また、２２００℃を越えて高くなると、窒化硼素と炭素の反応によりＢ4Ｃを生成あるいは窒化硼素の昇華などを生じ、形状、色目、書き味等を損ねてしまうので、好ましくない。
窒化硼素が生成する反応機構は、Ｂ2Ｏ3の還元反応で、次の反応式による。
３／２Ｃ＋Ｂ2Ｏ3＋Ｎ2 → ２ＢＮ＋３／２ＣＯ2
Ｃ＋Ｂ2Ｏ3＋２ＮＨ3 → ２ＢＮ＋ＣＯ2＋３Ｈ2
【００１６】
本発明において、焼成色鉛筆芯は、上記で得られた白色多孔質芯体の気孔内にインキを充填させることにより得られる。
白色多孔質芯体の気孔内にインキを充填させるインキとしては、従来公知の色鉛筆芯用のものであればいずれも使用することができる。例えば、染料、顔料等の着色剤を、動植物油、合成油、アルコール類、炭化水素油、水等に溶解、分散させ、あるいは必要に応じて樹脂、界面活性剤等をさらに添加し製造された一般的に用いられている印刷用インキ、スタンプインキ、ボールペンインキ、水性筆記用インキ等が用いられる。
【００１７】
また、白色多孔質芯体の気孔内にインキを充填させる方法としては、白色多孔質芯体をインキ中に浸漬し、加熱、減圧、加圧等の条件下で気孔内に充填させることにより行うことができる。さらに、上記浸漬操作等を繰り返し行ってもよい。
【００１８】
本発明の焼成色鉛筆芯の製造方法では、白色の多孔質芯体を得るために、体質材に白色の窒化硼素を用いることが可能であることは当然であり、通常の焼成芯に一般的に使用されている黒鉛を用いても、バインダー炭素共々黒鉛も窒化硼素化されるために、白色多孔質芯体に使用可能となる。
また、この製造方法は、窒化硼素化工程の以前の段階までは、既存の鉛筆芯と同様な設備で製造可能であり、これまで積み重ねてきた経験、既知となっている鉛筆芯の高強度化等の技術を充分に継投できる作用をもつ。
さらに、焼結性の六方晶窒化硼素を配合することにより、該六方晶窒化硼素の焼結により、滑らかな書き味を損なうことなく、白色多孔質芯体の強度をより引き上げることが可能となる。
【００１９】
【実施例】
次に、本発明を実施例により、更に具体的に説明するが、本発明はこれらの実施例によって何ら限定されるものでない。
【００２０】
（実施例１）
窒化硼素（平均粒子径：１０μｍ） ３０重量部
焼結性窒化硼素（平均粒子径：０．１μｍ） ２０重量部
塩化ビニル樹脂 ５０重量部
ジオクチルフタレート（ＤＯＰ） ２０重量部
ステアリン酸亜鉛 １重量部
上記配合組成物をヘンシェルミキサーで混合分散し、加圧ニーダー、二本ロールで混練した後、細線状に押出成形し、これから残留する可塑剤を除去すべく空気中で１８０℃にて１０時間熱処理して、しかるのち窒素雰囲気中にて３００℃迄は１０℃／ｈｒ、３００℃から１０００℃迄は３０℃／ｈｒで昇温させて、１０００℃にて１時間焼成し、黒色の焼成芯体を得た。
この黒色の焼成芯体を、硼酸と共に窒素雰囲気中で徐々に加熱して２０００℃にて２時間熱処理し、直径０．５７ｍｍの白色の多孔質芯体を得た。
次に、赤色インキ中に上記白色多孔質芯体を浸し、７０℃で２４時間放置した。この染料が充填された焼成芯体表面をアルコールで洗浄し、直径０．５７ｍｍの赤色の鉛筆芯を得た。
【００２１】
（実施例２）
体質材の窒化硼素を天然鱗片状黒鉛に置き換えた他は、全て実施例１と同様にして、直径０．５７ｍｍの赤色の鉛筆芯を得た。
【００２２】
（比較例１）
実施例１の窒化硼素化処理の温度を２０００℃から１２００℃とした他はすべて、実施例１と同様にした。
【００２３】
（比較例２）
実施例１の窒化硼素化処理の温度を２０００℃から２３００℃とした他はすべて、実施例１と同様にした。
【００２４】
上記実施例１〜２及び比較例１〜２の赤色の色鉛筆芯を使用して、ＪＩＳ−Ｓ−６００５−１９８９に準拠して曲げ強度（ＭＰａ）を測定すると共に、書き味及び描線の発色性について評価した。これらの結果を下記表１に示す。
なお、書き味、描線発色性の評価は、熟練者による官能試験により行った。
【００２５】
【表１】
（表１の考察）
上記表１から明らかなように、本発明となる実施例１〜２の焼成色鉛筆芯は、曲げ強度は一般の焼成色鉛筆芯と遜色なく高く、書き味も良好で、鮮明な発色性を持つことが判明した。
また、適正な反応温度範囲外での比較例１（１２００℃）は、バインダー炭素が窒化硼素化されず、目的の白色多孔質芯体は得られずに黒色のままで、さらに窒化硼素の焼結も起こらなかったため、強度も不十分である。比較例２（２４００℃）では、反応温度が高すぎたために、炭化硼素を生成してしまい、目的の白色多孔質芯体どころか、芯体としては劣悪なものとなった。
【００２７】
【発明の効果】
本発明によれば、従来にない全く新規な方法で、機械的強度に優れた白色多孔質芯体を得ることができ、該白色多孔質芯体の気孔内にインキを充填して着色することにより、きわめて優れた発色性、描線濃度を持ち、容易に折れ難い高強度の焼成色鉛筆芯の製造方法が提供される。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for producing a fired colored pencil lead having excellent smooth writing quality and mechanical strength, that is, bending strength, tensile strength, impact strength, and the like, and sufficient color developability and line density.
[0002]
[Prior art]
A conventional fired colored pencil lead uses one and / or two or more types of clay as a binder, and is added to a constitution material such as boron nitride, and further, a heat-resistant pigment and a reaction accelerator as necessary. After the kneaded composition was kneaded and the kneaded product was extrusion molded, it was heat-treated to form a porous fired core, and the pores of the core were filled with ink and the like composed of a dye and a pigment. At this time, the important characteristics of the colored pencil lead are required to have high mechanical strength, good color development, and a high writing line density.
[0003]
However, the conventional fired colored pencil lead does not have sufficient mechanical strength and does not have sufficient density and color developability. Moreover, in order to color by filling with ink, the conditions of the compounding material to be used must be white or light color. Therefore, in order to achieve the above requirements, it is necessary to easily obtain a white porous core having a high porosity while maintaining sufficient mechanical strength as an essential condition.
[0004]
Recently, a technology for obtaining a white porous core that meets each of the above conditions has been developed. However, the present situation is that a white porous core that sufficiently satisfies each of the above conditions has not yet been obtained. .
For example, Japanese Examined Patent Publication No. 64-7113 is composed of a porous sintered body having a skeleton of at least a compound composed of boron and nitrogen, and ink filled in pores of the porous sintered body. A colored pencil lead and a composition containing at least boron compound or boron compound and boron are extruded and reacted with nitrogen or a gas containing nitrogen and hydrogen at high temperature to form a skeleton of at least boron and nitrogen. A method for producing a colored pencil lead is disclosed, in which a porous sintered body is prepared, and then ink is filled into pores of the porous sintered body.
[0005]
However, in this colored pencil lead and its manufacturing method, boron fine wire lead-like material (for example, B 2 O 3 ) is heat-treated at a high temperature in an atmosphere of at least nitrogen or nitrogen and hydrogen. By reacting with nitrogen (for example, B 2 O 3 + 2NH 3 → 2BN + 3H 2 O), the boron nitride (BN) produced by the reaction is directly changed into strongly sintered boron nitride, and the wire boron core (BN) produced by the reaction is converted into a thin wire lead core material. The sinterable binding material such as clay and resin is not necessary, but the above-mentioned nitrogen or direct boron nitride by heat treatment in an atmosphere composed of nitrogen and hydrogen is used. The formation is not yet sufficient in sinterability, and there is a problem that it does not have sufficient bending strength, tensile strength and impact strength, and sufficient color developability and line drawing density. Is Configuration of different action or the like, the technical idea is different.
[0006]
[Problems to be solved by the invention]
The object of the present invention is to solve the above-mentioned problems of the prior art, in particular, the problem in the case of finally using boron nitride as the above-mentioned conventional porous body. An object of the present invention is to provide a method for producing a calcined colored pencil lead having a good and smooth writing quality.
[0007]
[Means for Solving the Problems]
As a result of earnest research to solve the above problems, the present inventor has made contact with a specific mixed gas on a black fired core obtained by molding a compounded composition containing at least a constitution material and a shaping material ( In order to complete the present invention, it was found that a white porous core was obtained by substituting boron nitride with carbon in the black fired core by contacting at a high temperature in a specific temperature range under an atmosphere). It has come.
That is, the method for producing a fired colored pencil core of the present invention comprises a black fired core formed by kneading, extruding, and firing at a high temperature, a compounded composition containing at least a graphite or boron nitride extender and an excipient. Contacted with a mixed gas of a boron-containing gas and a nitrogen-containing gas, heated to a temperature of 1400 to 2200 ° C. under the contact of the mixed gas, and white carbon in which carbon in the black fired core was replaced with boron nitride A porous core is prepared, and ink is filled in pores of the porous core.
In the manufacturing method, it is preferable to use sinterable boron nitride for a part or all of the extender.
The “sinterable boron nitride” defined in the present invention refers to boron nitride that is sintered at a high temperature (1400 ° C. or higher). Specifically, it is low crystalline boron nitride that suppresses grain growth. This means a boron nitride powder having an average particle size of about 0.1 to 0.5 μm and excellent bonding strength between particles.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail.
The method for producing a fired colored pencil core of the present invention comprises a black fired core obtained by kneading, extruding, and firing at a high temperature with a blended composition containing at least a graphite or boron nitride extender and an excipient. A white porous material obtained by contacting with a mixed gas of steam and nitrogen-containing gas, heating to a temperature of 1400 to 2200 ° C. under the contact of the mixed gas, and replacing carbon in the black fired core with boron nitride A core body is produced, and ink is filled in pores of the porous core body.
[0009]
In the present invention, first, a black fired core is produced using a blended composition containing at least an extender and a shaping material.
As the extender, for example, graphite, boron nitride and the like conventionally used for fired cores can be used, and sinterable (sintered) boron nitride is particularly limited as long as it sinters at a high temperature. Can be used.
Specifically, cubic boron nitride, hexagonal boron nitride, or the like can be used, and naturally, a mixture of these graphite, boron nitride, sintered boron nitride, or the like can also be used.
By using sinterable boron nitride for a part or all of the extender, a fired colored pencil lead having excellent mechanical strength such as bending strength can be obtained without impairing the smooth writing quality.
[0010]
Examples of the shaping material include organic shaping materials such as thermoplastic resins such as vinyl chloride resin, chlorinated vinyl chloride resin, and polyvinyl alcohol, thermosetting resins such as furan resin, phenol resin, and epoxy resin, Pitches such as natural polymer substances such as lignin, cellulose and tragacanth gum, petroleum asphalt, coal tar pitch, naphtha decomposition pitch, synthetic resin dry distillation pitch, etc. can be used, and naturally these several kinds of mixtures can also be used.
[0011]
Furthermore, water (purified water), dioctyl phthalate (DOP), dibutyl phthalate (DBP), tricresyl phosphate (TCP), adipine are used for the purpose of improving the characteristics during kneading performed by applying high shear force and improving the characteristics of extrusion molding. You may mix | blend the plasticizer of an organic shaping material, such as dioctyl acid (DOA), propylene carbonate, alcohols, ketones, esters, or 2 types or more as needed.
[0012]
These compounded compositions are sufficiently kneaded with a Henschel mixer, a pressure kneader, two rolls, etc., and then extruded into a thin line shape by an extruder, and then in a nitrogen atmosphere or an inert gas atmosphere such as argon gas. By firing in a non-oxidizing atmosphere, the extender is uniformly dispersed, sufficiently oriented, and an organic shaped material is carbonized to obtain a black fired core having carbon as a binder.
[0013]
The important point of the present invention is that the fired core obtained by the above method usually becomes a black core even if a white extender is used because of the binder carbon. Alternatively, a white porous core can be obtained by subjecting binder carbon to heat treatment (in an atmosphere) in contact with a mixed gas of oxygen-containing boron vapor and nitrogen-containing gas and replacing with boron nitride. A fired colored pencil core can be obtained by filling the pores of the porous core with ink and coloring.
The basic reaction of the present invention is a reduction reaction of oxygen-containing boron vapor such as B 2 O 2 and B 2 O 3 with graphite or binder carbon (C) and a reaction in which boron nitride is generated by nitrogen in the atmosphere. .
Since this reaction occurs on the surface of graphite or binder carbon, the reaction proceeds while the graphite or binder carbon layer is replaced with a boron nitride layer. In this way, it is possible to manufacture a boron nitride core having the same shape as that of the carbonaceous fired core used.
[0014]
In the present invention, the oxygen-containing boron vapor as a boron source is, for example, boron oxide such as B 2 O 2 and B 2 O 3 , BxNyOz (x, y, z are arbitrary positive integers, and so on) It can be easily obtained by heating a boron compound having a structure, boric acid having a HxByOz structure such as H 3 B 0 3 , HB 0 2 , H 2 B 4 0 7 , a mixture of these boric acids and carbon, or the like.
As the nitrogen-containing gas, the cheapest N 2 gas, NH 3 gas, cyan gas generated by the reaction between N 2 and a carbon material at a high temperature, or the like can be used.
The “mixed gas of oxygen-containing boron vapor and nitrogen-containing gas” defined in the present invention refers to a mixed gas of oxygen-containing boron vapor and nitrogen-containing gas, and graphite or binder carbon in the black fired core. The mixing ratio is not particularly limited as long as it is a mixed gas for replacing (C) with boron nitride.
[0015]
In the present invention, the reaction temperature under the contact of the above mixed gas (in the atmosphere) is such that the reaction proceeds more easily as the temperature increases, and it is necessary to perform the reaction at least in the range of 1400 ° C. or higher and 1400 to 2200 ° C.
When the reaction temperature is less than 1400 ° C., the progress of the reaction is delayed and a white porous core cannot be obtained. When the reaction temperature is higher than 2200 ° C., the reaction of boron nitride with carbon causes a B 4 reaction. This is not preferable because C is generated or sublimation of boron nitride is caused, and the shape, color, and writing quality are impaired.
The reaction mechanism in which boron nitride is generated is a reduction reaction of B 2 O 3 and is based on the following reaction formula.
3 / 2C + B 2 O 3 + N 2 → 2BN + 3 / 2CO 2
C + B 2 O 3 + 2NH 3 → 2BN + CO 2 + 3H 2
[0016]
In the present invention, the fired colored pencil lead is obtained by filling ink into the pores of the white porous core obtained above.
Any ink for filling the pores of the white porous core can be used as long as it is a conventionally known color pencil core. For example, colorants such as dyes and pigments are produced by dissolving and dispersing in animal and vegetable oils, synthetic oils, alcohols, hydrocarbon oils, water, etc., or adding resins, surfactants, etc. as necessary. Commonly used printing inks, stamp inks, ballpoint pen inks, water-based writing inks, and the like are used.
[0017]
As a method for filling the pores of the white porous core with ink, the white porous core is immersed in the ink and filled in the pores under conditions such as heating, reduced pressure, and pressure. be able to. Furthermore, you may perform the said immersion operation etc. repeatedly.
[0018]
In the method for producing a fired colored pencil lead of the present invention, it is natural that white boron nitride can be used as a material for obtaining a white porous core. Even if the graphite used is used, both the binder carbon and the graphite are boronized, so that it can be used for the white porous core.
In addition, this manufacturing method can be manufactured with the same equipment as the existing pencil lead up to the previous stage of the boron nitriding process, and the experience that has been accumulated so far has increased the strength of the known pencil lead. It has the function that can fully transfer the technology such as.
Furthermore, by blending the sinterable hexagonal boron nitride, the hexagonal boron nitride can be sintered to further increase the strength of the white porous core without impairing the smooth writing quality. .
[0019]
【Example】
EXAMPLES Next, although an Example demonstrates this invention further more concretely, this invention is not limited at all by these Examples.
[0020]
Example 1
Boron nitride (average particle size: 10 μm) 30 parts by weight Sinterable boron nitride (average particle size: 0.1 μm) 20 parts by weight Vinyl chloride resin 50 parts by weight Dioctyl phthalate (DOP) 20 parts by weight Zinc stearate 1 part by weight The blended composition is mixed and dispersed with a Henschel mixer, kneaded with a pressure kneader and two rolls, then extruded into a thin wire, and heat treated at 180 ° C. in air for 10 hours to remove the remaining plasticizer. Then, the temperature was raised at 10 ° C./hr from 300 ° C. to 30 ° C./hr from 300 ° C. to 1000 ° C. in a nitrogen atmosphere and baked at 1000 ° C. for 1 hour. Obtained.
This black fired core was gradually heated together with boric acid in a nitrogen atmosphere and heat-treated at 2000 ° C. for 2 hours to obtain a white porous core having a diameter of 0.57 mm.
Next, the white porous core was immersed in red ink and allowed to stand at 70 ° C. for 24 hours. The surface of the fired core filled with this dye was washed with alcohol to obtain a red pencil core having a diameter of 0.57 mm.
[0021]
(Example 2)
A red pencil lead having a diameter of 0.57 mm was obtained in the same manner as in Example 1 except that boron nitride as an extender was replaced with natural flake graphite.
[0022]
(Comparative Example 1)
The same procedure as in Example 1 was performed except that the temperature of the boron nitride treatment in Example 1 was changed from 2000 ° C. to 1200 ° C.
[0023]
(Comparative Example 2)
The same procedure as in Example 1 was performed except that the temperature of boron nitride treatment in Example 1 was changed from 2000 ° C. to 2300 ° C.
[0024]
Using the red colored pencil cores of Examples 1-2 and Comparative Examples 1-2 above, the bending strength (MPa) is measured according to JIS-S-6005-1989, and the color development of writing quality and strokes. Was evaluated. These results are shown in Table 1 below.
In addition, evaluation of writing taste and drawing line coloring property was performed by the sensory test by an expert.
[0025]
[Table 1]
(Consideration of Table 1)
As is clear from Table 1 above, the fired colored pencil lead of Examples 1 and 2 according to the present invention has a bending strength that is inferior to that of a general fired colored pencil lead, has good writing quality, and has a clear color developability. There was found.
Further, in Comparative Example 1 (1200 ° C.) outside the proper reaction temperature range, the binder carbon is not boron nitrided, the target white porous core is not obtained, and remains black. Since no crystallization occurred, the strength was insufficient. In Comparative Example 2 (2400 ° C.), since the reaction temperature was too high, boron carbide was produced, and the core body was inferior to the target white porous core.
[0027]
【The invention's effect】
According to the present invention, a white porous core having excellent mechanical strength can be obtained by a completely new method that has not been conventionally used, and the pores of the white porous core are filled with ink and colored. Thus, there is provided a method for producing a high-strength fired colored pencil lead that has extremely excellent color developability and drawn line density and is not easily broken.
Claims (2)
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP09031298A JP3938243B2 (en) | 1998-04-02 | 1998-04-02 | Manufacturing method of fired colored pencil lead |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP09031298A JP3938243B2 (en) | 1998-04-02 | 1998-04-02 | Manufacturing method of fired colored pencil lead |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH11286643A JPH11286643A (en) | 1999-10-19 |
| JP3938243B2 true JP3938243B2 (en) | 2007-06-27 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP09031298A Expired - Lifetime JP3938243B2 (en) | 1998-04-02 | 1998-04-02 | Manufacturing method of fired colored pencil lead |
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| Country | Link |
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| JP (1) | JP3938243B2 (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US7217378B2 (en) | 2003-09-10 | 2007-05-15 | Council Of Scientific & Industrial Research | Simple and efficient process for the preparation of pencil lead from spent pot-liners |
| JP5138317B2 (en) * | 2007-09-05 | 2013-02-06 | 三菱鉛筆株式会社 | Multilayer core and method for producing the same |
| JP6423158B2 (en) * | 2014-02-27 | 2018-11-14 | 三菱鉛筆株式会社 | Colored pencil lead |
-
1998
- 1998-04-02 JP JP09031298A patent/JP3938243B2/en not_active Expired - Lifetime
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| Publication number | Publication date |
|---|---|
| JPH11286643A (en) | 1999-10-19 |
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