JPH0542987B2 - - Google Patents
Info
- Publication number
- JPH0542987B2 JPH0542987B2 JP60168233A JP16823385A JPH0542987B2 JP H0542987 B2 JPH0542987 B2 JP H0542987B2 JP 60168233 A JP60168233 A JP 60168233A JP 16823385 A JP16823385 A JP 16823385A JP H0542987 B2 JPH0542987 B2 JP H0542987B2
- Authority
- JP
- Japan
- Prior art keywords
- average particle
- particle size
- fibrous material
- nrs
- except
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
Links
- 239000002245 particle Substances 0.000 claims description 17
- 239000002657 fibrous material Substances 0.000 claims description 13
- 239000000463 material Substances 0.000 claims description 13
- 238000004040 coloring Methods 0.000 claims description 6
- 238000004519 manufacturing process Methods 0.000 claims description 5
- 239000004606 Fillers/Extenders Substances 0.000 claims description 4
- 239000003086 colorant Substances 0.000 claims description 4
- 239000011230 binding agent Substances 0.000 claims description 3
- 238000005452 bending Methods 0.000 description 6
- 238000000034 method Methods 0.000 description 6
- 230000000052 comparative effect Effects 0.000 description 5
- 239000011777 magnesium Substances 0.000 description 5
- 229910052749 magnesium Inorganic materials 0.000 description 5
- FYYHWMGAXLPEAU-UHFFFAOYSA-N Magnesium Chemical compound [Mg] FYYHWMGAXLPEAU-UHFFFAOYSA-N 0.000 description 4
- CENHPXAQKISCGD-UHFFFAOYSA-N trioxathietane 4,4-dioxide Chemical compound O=S1(=O)OOO1 CENHPXAQKISCGD-UHFFFAOYSA-N 0.000 description 4
- ZWEHNKRNPOVVGH-UHFFFAOYSA-N 2-Butanone Chemical compound CCC(C)=O ZWEHNKRNPOVVGH-UHFFFAOYSA-N 0.000 description 3
- 239000000020 Nitrocellulose Substances 0.000 description 3
- NJLLQSBAHIKGKF-UHFFFAOYSA-N dipotassium dioxido(oxo)titanium Chemical compound [K+].[K+].[O-][Ti]([O-])=O NJLLQSBAHIKGKF-UHFFFAOYSA-N 0.000 description 3
- 229920001220 nitrocellulos Polymers 0.000 description 3
- -1 polyethylene Polymers 0.000 description 3
- 239000002904 solvent Substances 0.000 description 3
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 2
- 239000004698 Polyethylene Substances 0.000 description 2
- 238000005336 cracking Methods 0.000 description 2
- 238000001125 extrusion Methods 0.000 description 2
- 238000004898 kneading Methods 0.000 description 2
- 239000012860 organic pigment Substances 0.000 description 2
- 229920000573 polyethylene Polymers 0.000 description 2
- 239000001054 red pigment Substances 0.000 description 2
- KXGFMDJXCMQABM-UHFFFAOYSA-N 2-methoxy-6-methylphenol Chemical compound [CH]OC1=CC=CC([CH])=C1O KXGFMDJXCMQABM-UHFFFAOYSA-N 0.000 description 1
- 239000004793 Polystyrene Substances 0.000 description 1
- 239000004372 Polyvinyl alcohol Substances 0.000 description 1
- 229910052581 Si3N4 Inorganic materials 0.000 description 1
- 235000021355 Stearic acid Nutrition 0.000 description 1
- 229920001893 acrylonitrile styrene Polymers 0.000 description 1
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 1
- CEGOLXSVJUTHNZ-UHFFFAOYSA-K aluminium tristearate Chemical compound [Al+3].CCCCCCCCCCCCCCCCCC([O-])=O.CCCCCCCCCCCCCCCCCC([O-])=O.CCCCCCCCCCCCCCCCCC([O-])=O CEGOLXSVJUTHNZ-UHFFFAOYSA-K 0.000 description 1
- 229940063655 aluminum stearate Drugs 0.000 description 1
- 239000010425 asbestos Substances 0.000 description 1
- IRERQBUNZFJFGC-UHFFFAOYSA-L azure blue Chemical group [Na+].[Na+].[Na+].[Na+].[Na+].[Na+].[Na+].[Na+].[Al+3].[Al+3].[Al+3].[Al+3].[Al+3].[Al+3].[S-]S[S-].[O-][Si]([O-])([O-])[O-].[O-][Si]([O-])([O-])[O-].[O-][Si]([O-])([O-])[O-].[O-][Si]([O-])([O-])[O-].[O-][Si]([O-])([O-])[O-].[O-][Si]([O-])([O-])[O-] IRERQBUNZFJFGC-UHFFFAOYSA-L 0.000 description 1
- 239000001055 blue pigment Substances 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 229920002301 cellulose acetate Polymers 0.000 description 1
- 239000012461 cellulose resin Substances 0.000 description 1
- 229920006026 co-polymeric resin Polymers 0.000 description 1
- 238000001035 drying Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 239000010439 graphite Substances 0.000 description 1
- 229910002804 graphite Inorganic materials 0.000 description 1
- 239000001023 inorganic pigment Substances 0.000 description 1
- 239000000314 lubricant Substances 0.000 description 1
- 238000000386 microscopy Methods 0.000 description 1
- 238000012544 monitoring process Methods 0.000 description 1
- QIQXTHQIDYTFRH-UHFFFAOYSA-N octadecanoic acid Chemical compound CCCCCCCCCCCCCCCCCC(O)=O QIQXTHQIDYTFRH-UHFFFAOYSA-N 0.000 description 1
- OQCDKBAXFALNLD-UHFFFAOYSA-N octadecanoic acid Natural products CCCCCCCC(C)CCCCCCCCC(O)=O OQCDKBAXFALNLD-UHFFFAOYSA-N 0.000 description 1
- 239000001053 orange pigment Substances 0.000 description 1
- 239000005011 phenolic resin Substances 0.000 description 1
- 229920001568 phenolic resin Polymers 0.000 description 1
- 229920002223 polystyrene Polymers 0.000 description 1
- 229920002451 polyvinyl alcohol Polymers 0.000 description 1
- 229920000915 polyvinyl chloride Polymers 0.000 description 1
- 239000004800 polyvinyl chloride Substances 0.000 description 1
- SCUZVMOVTVSBLE-UHFFFAOYSA-N prop-2-enenitrile;styrene Chemical compound C=CC#N.C=CC1=CC=CC=C1 SCUZVMOVTVSBLE-UHFFFAOYSA-N 0.000 description 1
- 238000004080 punching Methods 0.000 description 1
- 230000003014 reinforcing effect Effects 0.000 description 1
- 229910052895 riebeckite Inorganic materials 0.000 description 1
- HQVNEWCFYHHQES-UHFFFAOYSA-N silicon nitride Chemical compound N12[Si]34N5[Si]62N3[Si]51N64 HQVNEWCFYHHQES-UHFFFAOYSA-N 0.000 description 1
- 239000008117 stearic acid Substances 0.000 description 1
- 239000000454 talc Substances 0.000 description 1
- 229910052623 talc Inorganic materials 0.000 description 1
- 239000001052 yellow pigment Substances 0.000 description 1
Landscapes
- Inks, Pencil-Leads, Or Crayons (AREA)
Description
（産業上の利用分野）
この発明はシヤープペンシル、鉛筆などに使わ
れる非焼成型の色芯の製造方法に関する。詳しく
は、体質材の少くとも一部として繊維状物を使用
するものに係る。
（従来の技術）
曲げ強さを向上するために体質材の少くとも一
部として繊維状物を使用することは知られてい
る。例えは、特開昭52−88419号公報や特開昭56
−163171号公報にはチタン酸カリウムの繊維状物
を、特公昭48−18347号公報には黒鉛、炭素など
の繊維状物を、それぞれ使用することについて開
示がある。
（発明が解決しようとする問題点）
非焼成型の色芯の場合、繊維状物の使用によつ
て得られたものは往々にして縦割れを生じ易くな
つてしまう。つまり、筆記などをしている場合
に、色芯が繊維状物の配向方向に崩れてしまうの
である。
曲げ強さに優れ、かつ、縦割れも生じ難い非焼
成型の色芯を得ることが本発明の目的である。
（問題点を解決するための手段）
繊維状物の使用とともに、着色材として平均粒
径が0.1乃至1.0μｍのものを使用する。即ち、本
発明は、結合材と着色材と体質材とを少くとも主
材とし、混練、押出成形してなる非焼成型の色芯
の製造方法であつて、前記体質材の少くとも一部
として繊維状物を使用するものにおいて、前記着
色材として平均粒径が0.1乃至1.0μｍのものを使
用したことを特徴とする色芯の製造方法を要旨と
する。
以下詳述する。
結合材としては、ポリ塩化ビニル、ポリエチレ
ン、ポリスチレン、アクリロニトリル・スチレン
共重合樹脂、ニトロセルロース、酢酸セルロー
ス、フエノール樹脂、ポリビニルアルコールなど
例示でき、これらの中では、セルロース系樹脂、
中でもニトロセルロースが好ましい。また、体質
材の繊維状物としては、前記したものの外にも、
窒化硅素、アスベスト、アルミナ、マグネシウム
オキシサルフエートなど例示でき、これらの中で
は、チタン酸カリウムやマグネシウムオキシサル
フエートが好ましい。平均粒子径は1μｍあるい
はそれ以下、平均粒子長は10〜100μｍ程度のも
のが一般に良好である。尚、繊維状物以外の体質
材を併用してもよい。また、着色材としては、無
機顔料、有機顔料いずれも使用できるが、発色性
が良好な点で有機顔料が好ましい。この着色材の
平均粒径は0.1乃至1.0μｍである。0.1μｍ以下では
縦割れを生じ易く、1.0μｍ以上では曲げ強さが低
くなり実用的でない。より好ましくは0.3乃至
0.8μｍである。
以上の各材料のそれぞれ１種もしくは２種以
上、並びに、必要に応じて使用される滑剤、溶剤
などを均一に混ぜ合わせ、押出成形後、所定寸法
に整えて製品を得る。ここで、上記着色材の使用
量は溶剤を除く全量に対し10〜20重量％程度にし
ておくとよい。また途中、必要に応じて乾燥処理
など施す場合もある。
（実施例）
以下、実施例により説明する。なお、単に部と
あるのは重量部を示す。また、粒径測定は顕微鏡
法によつたものである。
実施例 １
ニトロセルロース 27部
マグネシウムオキシサルフエート（平均粒子径約
0.5μｍ、平均粒子長約50μｍ） 33部
ウオツチングレツドNRS（日本ピグメント社製の
赤色顔料：平均粒径約0.7μｍ） 16部
ステアリン酸 ４部
ステアリン酸アルミニウム 13部
ポリエチレンワツクス ７部
メチルエチルケトン 150部
上記材料を３本ロールで均一に混練し、溶剤分
を調整後、押出成形機にて細線状に押出し、風乾
にて十分乾燥させた後、所定寸法に切断して直径
0.5mmの赤色芯を得た。
実施例 ２
実施例１において、ウオツチングレツドNRS
をシユミラーフアーストオレンジＶ（大日本イン
キ(株)製の橙色顔料：平均粒径約0.3μｍ）に変えた
以外、すべて実施例１と同様にした。
実施例 ３
実施例１において、ウオツチングレツドNRS
をシユミラーフアーストイエロー5GS（大日本イ
ンキ(株)製の黄色顔料：平均粒径約0.5μｍ）に変え
た以外、すべて実施例１と同様にした。
実施例 ４
実施例１において、マグネシウムオキシサルフ
エートをチタン酸カリウム（平均粒子径約0.3μ
ｍ、平均粒子長約15μｍ）に変えた以外、すべて
実施例１と同様にした。
比較例 １
実施例１において、ウオツチングレツドNRS
をシユミラーネオゾールレツド2BY（大日本イン
キ(株)製の赤色顔料：平均粒径約0.08μｍ）に変え
た以外、すべて実施例１と同様にした。
比較例 ２
実施例１においてウオツチングレツドNRSを
群青1900（第一化成(株)製の青色顔料：平均粒径約
2μｍ）に変えた以外、すべて実施例１と同様に
した。
比較例 ３
実施例４において、ウオツチングレツドNRS
をネオゾールレツド2BY（前述）に変えた以外、
すべて実施例４と同様にした。
比較例 ４
実施例４において、ウオツチングレツドNRS
を群青1900（前述）に変えた以外、すべて実施例
４と同様にした。
比較例 ５
実施例１において、マグネシウムオキシサルフ
エートをタルク（平均粒径約3μｍ）に変えた以
外、すべて実施例１と同様にした。
（発明の効果）
各例で得たものの曲げ強さ及び耐縦割れ性につ
いての試験結果を表−１に示す。尚、曲げ強さは
JISS6005に準じ、また、耐縦割れ性は製品をノ
ツク式シヤープペンシルの芯タンクに収容し、先
端から1.5mm突出するようノツクを繰り返し、60°
の筆記角度で400ｇの筆記荷重を加えたときの縦
割れ発生回数（測定回数は10回）を示す。
(Industrial Application Field) The present invention relates to a method for producing a non-fired color core used in sharpening pencils, pencils, etc. Specifically, the invention relates to those in which a fibrous material is used as at least a part of the body material. (Prior Art) It is known to use a fibrous material as at least a part of a structural material in order to improve bending strength. For example, JP-A-52-88419 and JP-A-56
Japanese Patent Publication No. 163171 discloses the use of a fibrous material of potassium titanate, and Japanese Patent Publication No. 18347-1987 discloses the use of a fibrous material of graphite, carbon, etc. (Problems to be Solved by the Invention) In the case of non-fired colored cores, those obtained by using fibrous materials often tend to cause longitudinal cracks. In other words, when writing or the like, the color core collapses in the direction of orientation of the fibrous material. It is an object of the present invention to obtain a non-fired color core that has excellent bending strength and is less likely to cause vertical cracks. (Means for solving the problem) In addition to using a fibrous material, a colorant having an average particle size of 0.1 to 1.0 μm is used. That is, the present invention is a method for producing a non-fired colored core, which is made of at least a binder, a coloring material, and an extender as main materials, and is formed by kneading and extrusion molding, wherein at least a portion of the extender is kneaded and extruded. The gist of the present invention is a method for producing a colored core, which uses a fibrous material as the coloring material, and is characterized in that the colorant has an average particle size of 0.1 to 1.0 μm. The details will be explained below. Examples of the binder include polyvinyl chloride, polyethylene, polystyrene, acrylonitrile-styrene copolymer resin, nitrocellulose, cellulose acetate, phenolic resin, and polyvinyl alcohol. Among these, cellulose resin,
Among them, nitrocellulose is preferred. In addition to the above-mentioned fibrous materials, there are also
Examples include silicon nitride, asbestos, alumina, and magnesium oxysulfate. Among these, potassium titanate and magnesium oxysulfate are preferred. Generally, the average particle diameter is 1 μm or less, and the average particle length is about 10 to 100 μm. In addition, a physical material other than the fibrous material may be used in combination. Further, as the coloring material, both inorganic pigments and organic pigments can be used, but organic pigments are preferable since they have good coloring properties. The average particle size of this colorant is 0.1 to 1.0 μm. If it is less than 0.1 μm, vertical cracks are likely to occur, and if it is more than 1.0 μm, the bending strength becomes low and is not practical. More preferably 0.3 to
It is 0.8 μm. One or more of the above materials, as well as lubricants and solvents used as necessary, are mixed uniformly, and after extrusion molding, the product is shaped into a predetermined size to obtain a product. Here, the amount of the coloring material used is preferably about 10 to 20% by weight based on the total amount excluding the solvent. In addition, drying treatment may be performed as necessary during the process. (Example) Examples will be described below. Note that parts simply indicate parts by weight. In addition, the particle size was measured by microscopy. Example 1 Nitrocellulose 27 parts Magnesium oxysulfate (average particle size approx.
0.5 μm, average particle length approx. 50 μm) 33 parts Watching Red NRS (red pigment manufactured by Nippon Pigment Co., Ltd.: average particle size approx. 0.7 μm) 16 parts stearic acid 4 parts aluminum stearate 13 parts polyethylene wax 7 parts methyl ethyl ketone 150 After uniformly kneading the above materials with three rolls and adjusting the solvent content, extrude them into fine wires with an extruder, thoroughly dry them with air, and then cut them into specified dimensions.
A 0.5 mm red core was obtained. Example 2 In Example 1, the watching lead NRS
The procedure was the same as in Example 1, except that Shmirer First Orange V (orange pigment manufactured by Dainippon Ink Co., Ltd.: average particle size of about 0.3 μm) was used. Example 3 In Example 1, the monitoring lead NRS
The procedure was the same as in Example 1, except that Shmirer First Yellow 5GS (yellow pigment manufactured by Dainippon Ink Co., Ltd.: average particle size of about 0.5 μm) was used. Example 4 In Example 1, magnesium oxysulfate was mixed with potassium titanate (average particle size of about 0.3 μm).
The procedure was the same as in Example 1 except that the average particle length was changed to 15 μm. Comparative Example 1 In Example 1, the watching lead NRS
The procedure was the same as in Example 1 except that the material was changed to Simirer Neosol Red 2BY (red pigment manufactured by Dainippon Ink Co., Ltd.: average particle size of about 0.08 μm). Comparative Example 2 In Example 1, the watching red NRS was replaced with Ultramarine 1900 (blue pigment manufactured by Daiichi Kasei Co., Ltd.: average particle size of approx.
Everything was the same as in Example 1 except that the thickness was changed to 2 μm). Comparative Example 3 In Example 4, the watching lead NRS
Other than changing to Neosol Red 2BY (mentioned above),
Everything was the same as in Example 4. Comparative Example 4 In Example 4, the watching lead NRS
Everything was the same as in Example 4, except that Gunjo 1900 (described above) was used. Comparative Example 5 The same procedure as in Example 1 was carried out except that magnesium oxysulfate was replaced with talc (average particle size of about 3 μm). (Effects of the Invention) Table 1 shows the test results for the bending strength and longitudinal cracking resistance of the samples obtained in each example. Furthermore, the bending strength is
In accordance with JISS6005, the vertical cracking resistance was determined by placing the product in the lead tank of a knock-type sharp pencil and repeatedly punching it so that it protruded 1.5 mm from the tip.
It shows the number of times vertical cracks occur (measured 10 times) when a writing load of 400g is applied at a writing angle of .
【表】【table】
【表】
この表−１より判るように、本発明によれば、
繊維状物による補強効果が十分に発揮され、従つ
て、曲げ強さに優れたものであつて、繊維状物を
使用したときの縦割れの発生も十分に抑制された
製品を得ることができる。[Table] As can be seen from Table 1, according to the present invention,
It is possible to obtain a product in which the reinforcing effect of the fibrous material is fully exhibited, and therefore, the product has excellent bending strength and the occurrence of vertical cracks is sufficiently suppressed when the fibrous material is used. .
Claims (1)
し、混練、押出成形してなる非焼成型の色芯の製
造方法であつて、前記体質材の少くとも一部とし
て繊維状物を使用するものにおいて、前記着色材
として平均粒径が0.1乃至1.0μｍのものを使用し
たことを特徴とする色芯の製造方法。1. A method for producing a non-fired colored core made of at least a binder, a coloring material, and an extender as main materials, kneaded and extruded, wherein a fibrous material is used as at least a part of the extender. A method for producing a color core, characterized in that the colorant has an average particle size of 0.1 to 1.0 μm.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP16823385A JPS6227480A (en) | 1985-07-30 | 1985-07-30 | Production of color lead |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP16823385A JPS6227480A (en) | 1985-07-30 | 1985-07-30 | Production of color lead |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS6227480A JPS6227480A (en) | 1987-02-05 |
| JPH0542987B2 true JPH0542987B2 (en) | 1993-06-30 |
Family
ID=15864243
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP16823385A Granted JPS6227480A (en) | 1985-07-30 | 1985-07-30 | Production of color lead |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS6227480A (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO1999061537A1 (en) | 1998-05-27 | 1999-12-02 | Sakura Color Products Corporation | Non-calcined marrow of colored pencil |
| JP2001226203A (en) * | 2000-02-10 | 2001-08-21 | Fumakilla Ltd | Mothproof method for clothes and insect repellent for clothes used therefor |
| JP2020002191A (en) * | 2018-06-25 | 2020-01-09 | 三菱鉛筆株式会社 | Non-calcined pencil lead |
Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5288419A (en) * | 1976-01-20 | 1977-07-23 | Tonbo Pencil | Pencil lead composition |
| JPS534631A (en) * | 1976-07-02 | 1978-01-17 | Tonbo Pencil | Method of manufacturing fluorescent color pencil lead |
| JPS54121829A (en) * | 1978-03-10 | 1979-09-21 | Pentel Kk | Method of making lead for color pencil |
| JPS56163171A (en) * | 1980-05-21 | 1981-12-15 | Mitsubishi Pencil Co Ltd | Uncalcined pencil lead |
| JPS585952A (en) * | 1981-07-03 | 1983-01-13 | Hitachi Ltd | Charged-particle focusing deflecting device |
-
1985
- 1985-07-30 JP JP16823385A patent/JPS6227480A/en active Granted
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5288419A (en) * | 1976-01-20 | 1977-07-23 | Tonbo Pencil | Pencil lead composition |
| JPS534631A (en) * | 1976-07-02 | 1978-01-17 | Tonbo Pencil | Method of manufacturing fluorescent color pencil lead |
| JPS54121829A (en) * | 1978-03-10 | 1979-09-21 | Pentel Kk | Method of making lead for color pencil |
| JPS56163171A (en) * | 1980-05-21 | 1981-12-15 | Mitsubishi Pencil Co Ltd | Uncalcined pencil lead |
| JPS585952A (en) * | 1981-07-03 | 1983-01-13 | Hitachi Ltd | Charged-particle focusing deflecting device |
Also Published As
| Publication number | Publication date |
|---|---|
| JPS6227480A (en) | 1987-02-05 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| JP5410519B2 (en) | Cores for writing, drawing and / or drawing tools | |
| JPH0542987B2 (en) | ||
| JPH06293874A (en) | Production of pencil lead | |
| DE2234737C3 (en) | Composition for extruding a sharpenable jacket around a lead and method for producing a pen | |
| JPH0519589B2 (en) | ||
| JPH06157974A (en) | Non-baked color-pencil lead core and its production | |
| JPH07126568A (en) | Nonbaked color pencil lead and its production | |
| JP3062039B2 (en) | Non-fired pencil lead | |
| JPS623189B2 (en) | ||
| JPS621769A (en) | Colored lead | |
| KR100860499B1 (en) | Pencil Lead Composition and Pencil Lead Manufacturing Thereby | |
| AU2020335099B2 (en) | Core for writing, drawing and/or painting implements and method for the production thereof | |
| JP3785793B2 (en) | Manufacturing method of colored pencil lead | |
| WO2023017643A1 (en) | Unfired pencil core | |
| JPH07316483A (en) | Color pencil lead | |
| JPS6139996B2 (en) | ||
| JP2002138239A (en) | Solid drawing material | |
| JPH066690B2 (en) | Color pencil lead manufacturing method | |
| JPH05302054A (en) | Color pencil lead | |
| JPH0260978A (en) | Colored pencil lead | |
| JP3820773B2 (en) | Colored pencil lead | |
| JPH083504A (en) | Production of non-baked pencil lead | |
| JPH03784A (en) | Colored pencil lead | |
| JP3035157B2 (en) | Manufacturing method of non-fired pencil lead | |
| JPH0912960A (en) | Colored pencil lead |