Color pencil lead

Abstract

Provided is a color pencil lead which is excellent in a hue, a light resistance and a strength and can be erased with an eraser and which is suited to pencil leads for mechanical pencils and wooden pattern holder pencils. The above color pencil lead is characterized by containing a resin in which a dye is dissolved or included in a pencil lead body.

Claims

1. A. color pencil lead containing a resin which is at least one of modified phenol resin, ketone resin, maleic acid resin and aldehyde resin, wherein the resin in which a dye is dissolved or included has a film form having a thickness of 1 m or less in a pencil lead body.

2. The color pencil lead as described in claim 1, wherein the resin in which the dye is dissolved or included is soluble in an organic solvent.

3. The color pencil lead as described in claim 1, wherein the pencil lead body is a calcined ceramic lead body prepared by blending at least boron nitride with a ceramic binder and calcining the blending.

4. The color pencil lead as described in claim 1, wherein the pencil lead body is a non-calcined ceramic lead body prepared by blending at least a ceramic binder and molding the blending.

5. The color pencil lead as described in claim 1, wherein the pencil lead body is a non-calcined ceramic lead body prepared by blending at least talc with a resin and molding the blending.

6. The color pencil lead as described in claim 1, wherein the pencil lead body is a calcined lead body prepared by blending at least graphite and calcining the blending.

7. The color pencil lead as described in claim 1, wherein it is impregnated with a lubricant.

8. A color pencil lead containing a resin in which a dye is dissolved or included, the resin being selected from the group consisting of modified phenol resins, ketone resins, maleic acid resins and aldehyde resins; or the resin in which the dye is included being selected from the group consisting of butyral resins, modified phenol resins, ketone resins, maleic acid resins, aldehyde resins, alkyl celluloses, acryl resins and sulfonic acid resins.

Description

EXAMPLES

(1) Next, the present invention shall be explained in further details with reference to examples and comparative examples, but the present invention shall not be restricted to the examples and the like shown below.

Example 1

(2) Blend Composition:

(3) TABLE-US-00001 Vinyl chloride resin 40% by mass Dioctyl phthalate (DOP) 10% by mass Boron nitride 50% by mass

(4) The blend composition described above was kneaded, and the kneaded matter was extruded and molded in the form of a fine line by means of an extruding equipment, followed by heating the fine line at 1000 C. for 5 hours under an inert gas atmosphere to prepare a calcined lead body of boron nitride and binder carbon. The above calcined lead body was heated at 700 C. for 12 hours under an air atmosphere to prepare a calcined lead body of only boron nitride. The above lead body was impregnated with Silicate 40 (manufactured by Colcoat Co., Ltd.), dried and heated at 1000 C. for 5 hours under an inert atmosphere to prepare a white calcined lead body.

(5) The above white lead body was impregnated with the following blend composition and dried at 80 C. for 12 hours.

(6) Blend Composition:

(7) TABLE-US-00002 Spilon Red C-PH 20% by mass (manufactured by Hodogaya Chemical Co., Ltd.) Butyral resin: S-LEC BL-1 20% by mass (manufactured by Sekisui Chemical Co., Ltd.) Isopropyl alcohol (hereinafter referred to as IPA) 60% by mass

(8) The pores of the calcined lead body obtained by the above drying were impregnated with an -olefin oil (Spectrasin 4: manufactured by Mobil Oil Co., Ltd.) at 100 C. for 6 hours to obtain a red lead for a mechanical pencil having a diameter of 0.564 mm and a length of 60 mm.

(9) In the embodiment of the present example, the pores of the pencil lead body are impregnated with the resin in which the dye is dissolved. That is, IPA is volatilized by the drying described above, and Spilon Red C-PH stays in a situation in which it is dissolved in the butyral resin and stabilized.

Example 2

(10) Blend composition:

(11) TABLE-US-00003 Smectite 40% by mass Distilled water 10% by mass Boron nitride 50% by mass

(12) The blend composition described above was kneaded, and the above kneaded matter was extruded and molded in the form of a fine line by means of an extruding equipment, followed by heating the fine line at 1200 C. for 5 hours in an inert gas atmosphere to prepare a calcined lead body of boron nitride and smectite.

(13) The above lead body was impregnated with the following blend composition and dried at 80 C. for 12 hours.

(14) Blend Composition:

(15) TABLE-US-00004 Ink A Spilon Red C-GH 20% by mass (manufactured by Hodogaya Chemical Co., Ltd.) Butyral resin: S-LEC BL-1 20% by mass (manufactured by Sekisui Chemical Co., Ltd.) IPA 60% by mass

(16) The pores of the calcined lead body obtained by the above drying were impregnated with the -olefin oil (Spectrasin 4: manufactured by Mobil Oil Co., Ltd.) at 60 C. for 6 hours to obtain a red lead for a mechanical pencil having a diameter of 0.564 mm and a length of 60 mm.

(17) In the embodiment of the present example, the pores of the pencil lead body are impregnated with the resin in which the dye is dissolved. That is, at the time when the ink A described above is dried, Spilon Red C-GH stays in a situation in which it is dissolved in the butyral resin and stabilized.

Example 3

(18) A red lead for a mechanical pencil having a diameter of 0.564 mm and length of 60 mm was obtained in the same manner as in Example 2, except that the ink A described above used in Example 2 was changed to an ink B comprising the following blend composition.

(19) Preparation of Ink B:

(20) TABLE-US-00005 Dimethyldistearylammonium salt 20% by mass C.I. Acid Red 10% by mass Distilled water 70% by mass

(21) A 18% by mass hydrochloric acid aqueous solution was dropwise added to the composition described above while stirring to adjust the pH to an acidic side, and then the solution was filtrated. Further, the filtrated matter was further washed with water and a solvent and then dried to thereby obtain a salt-forming dye.

(22) The above salt-forming dye was mixed with toluenesulfonamide and subjected to polycondensation therewith to obtain a color material B, and this was diluted in the following composition to prepare an ink B.

(23) TABLE-US-00006 Color material B 30% by mass IPA 70% by mass

(24) In the embodiment of the present example, the pores of the pencil lead body are filled with the resin in which the dye is included. That is, IPA is volatilized by drying, and the salt-forming dye described above stays in a situation in which it is included in the resin prepared by the polycondensation.

Example 4

(25) Blend Composition:

(26) TABLE-US-00007 Carboxymethyl cellulose 30% by mass DPP Red 20% by mass Talc 40% by mass Distilled water 10% by mass

(27) The blend composition described above was kneaded, and the kneaded matter was extruded and molded in the form of a fine line by means of an extruding equipment, followed by drying the fine line at 80 C. for 24 hours in the air. Then, the molding was impregnated with the ink A prepared in Example 2 described above and dried at 80 C. for 12 hours. Finally, the pores of the lead body obtained by drying were impregnated with the -olefin oil (Spectrasin 4: manufactured by Mobil Oil Co., Ltd.) at 60 C. for 6 hours to obtain a red lead for a mechanical pencil having a diameter of 0.564 mm and a length of 60 mm.

(28) In the embodiment of the present example, the resin in which the dye is dissolved is contained in the pencil lead body. That is, Spilon Red C-GH stays in a situation in which it is dissolved in the butyral resin and stabilized by the drying described above.

Example 5

(29) Blend Composition:

(30) TABLE-US-00008 Talc 50% by mass Spilon Red C-GH 10% by mass (manufactured by Hodogaya Chemical Co., Ltd.) Alkylphenol resin: (Hitanol 1501, 20% by mass manufactured by Hitachi Chemical Co., Ltd.) Benzyl alcohol 20% by mass

(31) First, Spilon Red C-GH and the alkylphenol resin described above were kneaded, and then the remaining components were added thereto and kneaded. The kneaded matter was extruded and molded in the form of a fine line by means of an extruding equipment and dried at 100 C. for 12 hours. Finally, the pores of the lead body obtained by drying were impregnated with the -olefin oil (Spectrasin 4: manufactured by Mobil Oil Co., Ltd.) at 100 C. for 6 hours to obtain a red lead for a mechanical pencil having a diameter of 0.564 mm and a length of 60 mm.

(32) In the embodiment of the present example, the resin in which the dye is dissolved is contained in the pencil lead body. That is, Spilon Red C-GH stays in a situation in which it is dissolved in the alkylphenol resin by the kneading of Spilon Red C-GH and the alkylphenol resin which has been carried out previously.

Example 6

(33) Blend Composition:

(34) TABLE-US-00009 Vinyl chloride resin 40% by mass DOP 10% by mass Natural scaly graphite 50% by mass

(35) The blend composition described above was kneaded, and the above kneaded matter was extruded and molded in the form of a fine line by means of an extruding equipment, followed by heating the fine line at 1000 C. for 5 hours in an inert atmosphere to prepare a calcined lead body of graphite and binder carbon. The above lead body was impregnated with the ink A prepared in Example 2 described above and dried at 80 C. for 12 hours. Finally, the pores of the lead body obtained by drying were impregnated with the -olefin oil (Spectrasin 4: manufactured by Mobil Oil Co., Ltd.) at 100 C. for 6 hours to obtain a brown lead for a mechanical pencil having a diameter of 0.564 mm and a length of 60 mm.

(36) In the embodiment of the present example, the pores of the pencil lead body are filled with the resin in which the dye is dissolved. That is, Spilon Red C-GH stays in a situation in which it is dissolved in the butyral resin and stabilized by the drying described above.

Comparative Example 1

(37) Blend Composition:

(38) TABLE-US-00010 Boron nitride 40% by mass Kaolin 35% by mass Polyvinyl alcohol 18% by mass Polyethylene glycol 7% by mass

(39) The blend composition described above and water of the same weight were mixed and dispersed by means of a Henschel mixer and kneaded by means of a double roll to control a moisture content. Then, the kneaded matter was extruded and molded in the form of a fine line, and the fine line was subjected to heat treatment at 105 C. for 15 hours in the air in order to remove a moisture therefrom. Thereafter, the fine line was heated up to 1100 C. in an argon gas and calcined at 1100 C. for 1 hour. Further, it was heated and calcined at 700 C. in an oxidative atmosphere to remove carbon matters to obtain a white calcined lead body having a diameter of 0.57 mm.

(40) Next, the calcined lead body described above was dipped in a red solution comprising:

(41) TABLE-US-00011 Spilon Red C-GH 25% by mass (manufactured by Hodogaya Chemical Co., Ltd.) Ethyl alcohol: 25% by mass Oleyl alcohol: 50% by mass
and left standing at ordinary temperature for 24 hours. The lead body was taken out from the solution and then dried at 80 C. for 5 hours to remove ethyl alcohol to obtain a red lead for a mechanical pencil having a diameter of 0.564 mm and a length of 60 mm. In the above case, Spilon Red C-GH stays in a situation in which it is dissolved in oleyl alcohol and does not stay in a situation in which it is dissolved in the resin.

Comparative Example 2

(42) Blend Composition:

(43) TABLE-US-00012 Carboxymethyl cellulose 30% by mass DPP Red 20% by mass Talc 40% by mass Distilled water 10% by mass

(44) The blend composition described above was kneaded, and the kneaded matter was extruded and molded in the form of a fine line by means of an extruding equipment and dried at 80 C. for 24 hours in the air. The pores of the lead body thus obtained were impregnated with the -olefin oil (Spectrasin 4: manufactured by Mobil Oil Co., Ltd.) at 60 C. for 6 hours to obtain a red lead for a mechanical pencil having a diameter of 0.564 mm and a length of 60 mm. DPP Red used is a pigment and stays in a situation in which it is dissolved in the extender and the like, and it is neither included nor dissolved in the resin.

(45) It was confirmed by measuring by the following method that in Examples 1 to 6, the resin in which the dye was included had a film form having a thickness of 1 m or less.

(46) Also, the leads of the respective colors for a mechanical pencil obtained above were used to evaluate a flexural strength, a color developability of the drawn lines, a light resistance, and an erasability by the following test methods. The results thereof are shown in the following Table 1.

(47) Measuring Method of Thickness of Resin Film:

(48) The lead obtained was cut by a laser, and a cross section thereof was measured by means of an electron microscope (S-4800, manufactured by Hitachi High-Technologies Corporation).

(49) Test Methods:

(50) Evaluation Method of Flexural Strength:

(51) The flexural strength was measured (n=100) based on JIS-S-6005-2007.

(52) Evaluation Method of Color Developability of the Drawn Lines:

(53) Shown (n=100) by a chroma (a.sup.2+b.sup.2).sup.1/2 in a L*ab value measured by means of a spectral colorimeter as is the case with a density measuring method using a scriber prescribed in JIS S 6005: 2007.

(54) Evaluation Method of Light Resistance:

(55) Measured (n=100) was a color difference E*ab=[(L*)2+(a*)2+(b*)2] 1/2 observed in exposing the drawn lines scribed above based on JIS L 0841:2004.

(56) Evaluation Method of Erasability:

(57) An erasing rate (five reciprocations) was measured (n=100) according to E (character erasing rate: =erasing rate)=1M/C)100 (M: density of erased part, C: density of colored part) based on an erasing ability (character erasing rate) test of plastic character erasing disclosed in JIS S 6050-2008.

(58) TABLE-US-00013 TABLE 1 Example Comparative Example Comparative Example 1 2 3 Example 1 4 5 Example 2 6 Thickness of resin 0.05 0.04 0.05 0.95 0.13 0.01 film (m) Flexural strength (N) 0.48 0.40 0.42 0.38 0.32 0.40 0.20 0.75 Color developability 20.3 21.5 19.4 15.5 22.5 22.0 17.5 16.2 of drawn lines Light resistance 12.1 12.2 11.5 14.1 5.5 12.1 10.5 14.1 Erasability (%) 98.1 98.2 99.0 94.6 98.2 97.8 85.6 94.6

(59) Observing the results shown in Table 1 described above, the calcined color pencil leads prepared by using boron nitride as the raw material are compared in Examples 1 to 3 and Comparative Example 1; the non-calcined color pencil leads are compared in Examples 4 and 5 and Comparative Example 2; the calcined color pencil lead prepared by using graphite as the raw material is shown in Example 6; and it has become clear that the pencil leads prepared in Examples 1 to 6 falling in the scope of the present invention are excellent in a flexural strength, a color developability of the drawn lines, a light resistance, and an erasability as compared with the pencil leads prepared in Comparative Examples 1 and 2 falling outside the scope of the present invention.

INDUSTRIAL APPLICABILITY

(60) The color pencil leads of the present invention can suitably be used as color pencil leads for mechanical pencils and color pencil leads for wooden pattern holder pencils.