JP3770629B2 - Lead core - Google Patents

Description

【０００９】
この化合物は、〔−ＯＣＯＯ−〕というカーボネートの構造を持つことを特徴とし、下記化学式化２で示すように、ジメチルカーボネートと高級アルコールを原料として得られる合成潤滑油基剤である。
【００１０】
【化２】

【００１１】
ここで、Ｒ、Ｒ′は炭素数１２以上のアルキル基であり、特には炭素数１２〜１５のものが好適に用いられ、例えばミテックス社製のリアルカーボＳＲ−１０００、ＳＲ−１０００／１２や、ディアルカーボＭ−３、Ｌ−３、Ｈ−１、Ｈ−２などが挙げられる。
【００１２】
本発明においては、長鎖ジアルキルカーボネートのみを単独で使用してもよいが、他の油脂やワックスなど従来公知の物質と併用してもよく、書き味、濃度、強度など使用用途に応じて適宜選択して用いることができる。
【００１３】
本発明に用いる焼成芯体としては、着色材として黒鉛、カーボンブラックなど、また結合材として天然樹脂、合成樹脂、粘土、ピッチ、アスファルトなどを用い、必要に応じて溶剤などを添加してニーダー、三本ロールにて混練し、押出成形して焼成するといった、従来公知の材料や製造条件によって得られた芯体であればなんでもよく、通常の気孔を有する芯体や、また解重合型樹脂や熱昇華性樹脂などを用いて多孔質化した芯体など任意に使用される。
【００１４】
ここで、芯体の気孔中に含浸する方法としては、一般の油脂類と同様に常圧含浸、又は減圧、加圧含浸法を用いて、温度を７０〜１４０℃に保ち、粘度を下げて含浸を行うと、短時間に芯体内部にくまなく充填できる。その後、表面に付着した余分の長鎖ジアルキルカーボネートを遠心分離、または溶剤による洗浄等により除去して、目的とする鉛芯を作製する。
【００１５】
【実施例】
実施例１
外径が０．５７ｍｍで硬度ＨＢの焼成芯体に、長鎖ジアルキルカーボネート（ミテックス社製、リアルカーボＳＲ１０００）を９０℃で４時間の常圧下で含浸させ、含浸後直ちに遠心分離機にて表面の残余の油分を振り切って完成芯とした。
【００１６】
比較例１〜３
実施例１で用いた、外径が０．５７ｍｍで硬度ＨＢの焼成芯体に、含浸しないもの、また長鎖ジアルキルカーボネートの代わりにスピンドル油又はシリコーン油を、それぞれ実施例１と同様の含浸条件で含浸させたものを比較例とした。
【００１７】
上記実施例及び比較例による性能を比較すると、表１のようになった。なお、濃度試験は、ＪＩＳ−Ｓ６００５に基づいて測定したものであり、数値が大きいほど濃い。また定着性は、プロッタ（武藤工業社製ＸＦ３０３）で所定の図面をトレーシングペーパーに描かせ、これに白紙のトレーシングペーパーを重ねて、３００ｇの荷重でこすった場合の描画された方の紙面の汚れを、目視で確認した。
【００１８】
【表１】

【００１９】
【発明の効果】
本発明の鉛芯は、表１の結果からも明らかなように、筆跡の濃度増加効果が大きく、それにも係わらず定着性が良好で汚れが少ないという優れた特徴を有し、しかも書き味も滑らかとなっている。この特徴は、通常の筆記はもとより、プロッタでの筆記に用いた場合にはより顕著なものとなる。[0001]
[Industrial application fields]
The present invention relates to a lead core of a fired type, particularly used for a mechanical pencil or a plotter.
[0002]
[Prior art]
Conventionally, calcined lead cores are made by adding binders such as clay, natural polymer compounds, synthetic polymer compounds, pitches and asphalts to colorants such as graphite and carbon black, and if necessary, solvents and plasticizers And kneaded, and the kneaded product is extruded into a core, then fired at a temperature of 900 to 1000 ° C., and the resulting fired core is impregnated with fats and oils to form a finished core. .
[0003]
The fats and oils impregnated in the pores of the fired core include animal and vegetable oils such as whale oil, lard, rapeseed oil and soybean oil, or mineral oils such as spindle oil and liquid paraffin, as well as silicone oils and waxes. They are combined and appropriately selected for use.
[0004]
[Problems to be solved by the invention]
By the way, as described above, the fats and oils are impregnated in the pores of the fired core so as to increase the handwriting concentration and at the same time smooth the writing, but the conventional fats and oils have their merits and demerits, respectively. . That is, even if animal and vegetable oils and waxes are impregnated in the fired core, the handwriting concentration cannot be increased so much, and next, mineral oils cannot be expected to increase the handwriting concentration. Furthermore, silicone oil has the highest handwriting density among the above-mentioned oils and fats, but its fixability on the paper surface is not so good.
In addition to impregnation with fats and oils, various means have been proposed to increase the handwriting concentration, for example, there are a method of impregnating a dye and a method of impregnating a substance that forms a colored material. However, it is difficult to say that the initial purpose has been achieved, and there is a drawback that a problem occurs in erasability.
[0005]
[Means for Solving the Problems]
The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a lead core that has a large effect of increasing the handwriting density, has a smooth writing feel, and has excellent fixability to paper.
[0006]
The present invention is based on the premise that the lead core impregnation is not toxic, has no off-flavor, and has very little stability over time. The pores are filled easily and completely, the density of the handwriting is increased as much as possible when impregnated into the fired core, and there is no fixing to the paper surface, that is, no stain on the paper surface. As a result of intensive research on materials having conditions such as the ability to help uniform and smooth disintegration and smooth brush strokes.
[0007]
The present invention is characterized in that long-chain dialkyl carbonate is used as a substance to be impregnated in the pores of the fired core from the above viewpoint, and the structural formula thereof is shown in Chemical Formula 1.
[0008]
[Chemical 1]

[0009]
This compound has a carbonate structure of [—OCOO—], and is a synthetic lubricant base obtained from dimethyl carbonate and a higher alcohol as raw materials, as shown in the following chemical formula 2.
[0010]
[Chemical 2]

[0011]
Here, R and R ′ are alkyl groups having 12 or more carbon atoms, and those having 12 to 15 carbon atoms are particularly preferably used. For example, Real Carbo SR-1000, SR-1000 / 12 manufactured by Mitex Corporation , Dial Carbo M-3, L-3, H-1, H-2 and the like.
[0012]
In the present invention, only a long-chain dialkyl carbonate may be used alone, but it may be used in combination with other conventionally known substances such as other oils and waxes, depending on the intended use such as writing taste, concentration, strength, etc. It can be selected and used.
[0013]
As the fired core used in the present invention, graphite, carbon black, etc. as a colorant, and natural resin, synthetic resin, clay, pitch, asphalt, etc., as a binder, a kneader with addition of a solvent as necessary, Any core that is obtained by a conventionally known material or manufacturing conditions, such as kneading with a three roll, extrusion molding and firing, may be used, and a core having normal pores, a depolymerizing resin, A core body made porous using a heat sublimable resin or the like is arbitrarily used.
[0014]
Here, as a method of impregnating the pores of the core body, the pressure is maintained at 70 to 140 ° C. and the viscosity is lowered by using normal pressure impregnation, or reduced pressure and pressure impregnation methods as in general fats and oils. When impregnated, the core body can be filled in a short time. Thereafter, excess long-chain dialkyl carbonate adhering to the surface is removed by centrifugation, washing with a solvent, or the like to produce a target lead core.
[0015]
【Example】
Example 1
A fired core having an outer diameter of 0.57 mm and a hardness of HB is impregnated with long-chain dialkyl carbonate (made by Mitex, Real Carbo SR1000) at 90 ° C. under normal pressure for 4 hours. The remaining oil was shaken off to make a finished core.
[0016]
Comparative Examples 1-3
The same impregnation conditions as in Example 1 were used for the fired core body having an outer diameter of 0.57 mm and having a hardness of HB, which was not impregnated, and spindle oil or silicone oil instead of long-chain dialkyl carbonate used in Example 1. The sample impregnated with was used as a comparative example.
[0017]
Table 1 shows a comparison of the performance of the examples and comparative examples. In addition, the density | concentration test is measured based on JIS-S6005, and it is so deep that a numerical value is large. Also, the fixing property is that of the drawing surface when a predetermined drawing is drawn on a tracing paper with a plotter (XF303 manufactured by Muto Kogyo Co., Ltd.) and a blank tracing paper is superimposed on this and rubbed with a load of 300 g. The soil was visually confirmed.
[0018]
[Table 1]

[0019]
【The invention's effect】
As is clear from the results of Table 1, the lead core of the present invention has a great effect of increasing the density of handwriting, and nevertheless has excellent characteristics such as good fixability and little stains, and also has a good writing quality. It is smooth. This feature becomes more prominent when used for plotter writing as well as normal writing.

Claims (1)

A lead core obtained by impregnating at least a long-chain dialkyl carbonate into the pores of the fired core.