TW202120633A - Baked color pencil lead - Google Patents

Abstract

To provide a color pencil lead which exhibits excellent physical strength, while having excellent writing erasability and smooth feel of writing. A color pencil lead according to the present invention comprises: a porous lead body that contains an extender, an inorganic binder and a solid-state coloring agent; and a slightly volatile liquid that is filled in the pores of the porous lead body.

Description

Sintered color pencil lead

The invention relates to a color pencil lead. In more detail, the present invention relates to a color pencil lead with excellent color rendering and erasability, smooth writing feeling, and high physical strength.

Previously, color pencil cores used in mechanical pencils, etc., used color pencil cores made by the following method, that is, the main components of boron nitride and other solid materials and clay and other binders, and if necessary, contain organic polymer compounds, etc. The kneaded product is extruded and molded, and then the ink containing the dye is impregnated in the pores of the white porous substrate obtained by sintering at a high temperature. When using this kind of color pencil core to write notes on paper, the ink impregnated in the pores penetrates into the fibers of the paper. As a result, coloring components such as dyes penetrate into the paper. Therefore, the handwriting of the color pencil core is erased with an eraser. When erasing, the erasability of handwriting may decrease. [Prior Technical Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open No. 51-63744 [Patent Document 2] Japanese Patent Laid-Open No. 61-23667 [Patent Document 3] Japanese Patent Publication No. 61-142835 [Patent Document 4] Japanese Patent Laid-Open No. 07-041723

[The problem to be solved by the invention]

The present invention provides a color pencil lead with excellent erasability of handwriting, smooth writing feeling, and high physical strength. [Technical means to solve the problem]

The characteristics of the color pencil lead of the present invention are: It is made of porous core and non-volatile liquid. The above-mentioned porous core system is composed of a body material, an inorganic binder and a solid colorant, The non-volatile liquid is filled in the pores of the porous core.

Moreover, the manufacturing method of the color pencil lead of the present invention is characterized by including the following steps: (a) The mixing step, which involves mixing the body material and the inorganic binder to prepare a mixture; (b) The extrusion step, which is to extrude the above-mentioned mixture to produce a linear molded product; (c) A firing step, which is firing the above-mentioned linear shaped article to produce a porous substrate; (d) An impregnation step, which involves contacting a solution or dispersion containing a colorant and a low-viscosity organic solvent with the porous substrate to be impregnated therein; (e) A drying step, which heats the porous substrate after the impregnation step to remove part or all of the low-viscosity organic solvent in the pores, thereby leaving the solid colorant in the pores Inside, and form voids, thereby forming a porous core; (f) A filling step, which involves bringing the porous core into contact with a non-volatile liquid, and filling the voids with the non-volatile liquid. [Effects of Invention]

When using the color pencil core of the present invention to take notes, the colorant can be prevented from penetrating into the paper. When erasing with an eraser, the coloring agent on the surface of the paper can be easily removed, so excellent erasability can be achieved. Furthermore, a smooth writing feeling is obtained by impregnating the non-volatile liquid, and further, the physical strength of the colored pencil lead becomes high and it is not easy to break.

＜Color pencil lead＞ The color pencil core of the present invention is composed of a porous core and a non-volatile liquid filled in the pores of the porous core. Hereinafter, these structures will be explained as follows.

The porous core system used in the color pencil core of the present invention contains a body material and an inorganic binder as main components. Examples of the bulk material include white bulk materials such as titanium oxide, mica, talc, boron nitride, alumina, and calcium carbonate, or colored bulk materials such as molybdenum disulfide, tungsten disulfide, and graphite. The color pencil lead of the present invention is ideal for forming bright handwriting. In addition, when a fluorescent coloring agent is used as a coloring agent to form a fluorescent color handwriting, it is preferably one that does not hinder its color development. Therefore, in order to form high-brightness handwriting, it is better to use a white body material. In particular, if boron nitride is used, the body material does not hinder color development, and the strength of the pencil lead becomes higher, which is preferable.

Examples of the above-mentioned inorganic binder include: clays such as kaolin, halloysite, montmorillonite, sericite, bentonite, ceramics, zeolite, diatomaceous earth, activated clay, silica, aluminum phosphate , Silicone resin, silicone rubber, etc., which can be used alone or in combination.

The blending ratio of the body material and the inorganic binder as the main component of the porous core is not particularly limited, and it is preferably 9:1-7:3 in terms of mass ratio.

In the present invention, the solid colorant may be present in a part of the porous substrate mainly composed of a body material or an inorganic binder, and it may also be uniformly dispersed in the entire porous substrate, and is preferably present In a part of the porous core. Specifically, it is preferably in a state where the solid colorant is attached or adsorbed in the pores of the porous substrate. In this way, the colorant exists in the porous core in a solid state, and also exists in the final color pencil core, whereby the penetration of the colorant into the paper during writing is suppressed, and the erasability is improved. Here, typically, the solid colorant forms a layer or phase in the pores. That is, usually a uniform or uneven layer is formed on the inner surface of the pore, or it is attached to the inner surface of the pore in a block shape. In addition, the solid colorant may be in a completely dried state or in a solvated state. That is, a small amount of solvent or the like may be contained within a range where the layer or phase does not have fluidity.

In the present invention, the porous core system includes a body material, an inorganic binder, and a solid colorant. The pencil lead is usually manufactured by forming a mixture of the body material and the binder and then firing it. The same method can also be applied in the present invention. That is, it can be manufactured by firing a mixture of a body material and an inorganic binder, and adsorbing or attaching a solid colorant to the formed porous firing base material (details will be described later). In addition, it is also possible to mix the body material, the inorganic binder, and the coloring agent and fire it. In this case, it is preferable to use a coloring agent with higher heat resistance. On the other hand, if it is the former method, a coloring agent with lower heat resistance can also be used.

In addition, the porous core can also be manufactured by compressing a mixture of solid coloring materials, inorganic binders, inorganic materials, or water-soluble resins, etc., and optionally solid coloring materials under high pressure, and then immersing them in In water, solvents, etc., the above-mentioned inorganic substances or water-soluble resins, etc. are removed.

In addition, the porosity of the porous core used in the present invention is not particularly limited, but is preferably in the range of 5 to 40%, more preferably in the range of 10 to 30%. If it is less than 5%, the amount of solid colorant and non-volatile liquid in the pores will decrease, resulting in a color difference, or a tendency to produce some resistance during pen handling. If it is greater than 40%, the obtained porous core will be less. The tendency to break easily due to reduced strength. If it is in the range of 5-40%, the color rendering property is good, the writing feeling is smooth, and the strength of the sintered color pencil core can be maintained, which is preferable.

Furthermore, the porosity of the porous core used in the present invention can be measured by the following method with reference to JIS R1634 (1998). First, the dry mass (W1) of the porous core is measured. Then, it is immersed in a liquid with good permeability (for example, benzyl alcohol), the pores of the porous core are allowed to absorb the liquid until it is saturated, and then the mass in the liquid (W2) is measured. Then, the porous core was taken out of the liquid, and after removing the liquid adhering to the surface, the saturated liquid mass was measured (W3). Using these measured values, the porosity is obtained by the mathematical formula (1) shown below.

Porosity=(W3-W1)/(W3-W2)×100 (1)

As the solid colorant, dyes or pigments can be used. In addition, a coloring pigment obtained by coloring a resin with a dye can also be used. Dyes generally have low heat resistance, but they tend to penetrate into the porous core when they are made into a solution, so the production of the pencil lead of the present invention becomes easy. Therefore, the solid colorant is preferably a dye.

The dyes that can be used in the present invention are not particularly limited, and general dyes or fluorescent dyes can be mentioned.

Examples of general dyes include oil-soluble dyes, acid dyes, basic dyes, gold-containing dyes, and the like. In addition, as the salt-forming dyes of these dyes, there may be mentioned: salt-forming dyes of acid dyes and basic dyes, salt-forming dyes of basic dyes and organic acids, salt-forming dyes of acid dyes and organic amines, and basic dyes. Salt-forming dyes with resin acids and other types. Among these, from the viewpoints of color development or permeability to a porous core when prepared as a solution, and dissolution stability when prepared as a solution, salt-forming dyes are preferred. In addition, since the salt-forming dyes of organic acids and basic dyes, the salt-forming dyes of acid dyes and organic amines, and the salt-forming dyes of basic dyes and resin acids in the solution have higher solubility stability, they can be more strongly It exhibits the effect of the present invention, so it is preferably selected from the group consisting of these, and most preferably is a salt-forming dye of organic acid and basic dye.

More specifically, it can include: Valifast Black 1802, Valifast Black 1805, Valifast Black 1807, Valifast Violet 1701, Valifast Violet 1704, Valifast Violet 1705, Valifast Blue 1601, Valifast Blue 1605, Valifast Blue 1613, Valifast Blue 1621, Valifast Blue 1631, Valifast Red 1320, Valifast Red 1355, Valifast Red 1360, Valifast Yellow 1101, Valifast Yellow 1151, Nigrosine Base EXBP, Nigrosine Base EX, BASE OF BASIC DYES ROB-B, BASE OF BASIC DYES RO6G-B, BASE OF BASIC DYES VPB-B, BASE OF BASIC DYES VB-B, BASE OF BASIC DYES MVB-3 (Orient Chemical Industries Co., Ltd.), Aizen Spilon Black GMH-Special, Aizen Spilon Violet C-RH, Aizen Spilon Blue GNH, Aizen Spilon Blue 2BNH、Aizen Spilon Blue C-RH、Aizen Spilon Red C-GH、Aizen Spilon Red C-BH、Aizen Spilon Red C-PH、Aizen Spilon Yellow C-GNH、Aizen Spilon Yellow C-2GH、SPTBlue 111、SPTBlue GLSH-Special, SPTRed 533, SPTOrange 6, SBNViolet 510, SBNYellow 530, SBNBlue 570, Spilon Red C-BH (Hodogaya Chemical Industry Co., Ltd.) and other dyes.

Examples of fluorescent dyes include: Basic Yellow 1, Basic Yellow 40, Basic Red 1, Basic Red 1:1, Basic Red 13, Basic Violet 1, Basic Violet 7, Basic Violet 10. Basic Violet 11:1, Basic Orange 22, Basic Blue 7, Basic Green 1, Acid Yellow 3, Acid Yellow 7, Acid Red 52, Acid Red 77, Acid Red 87, Acid Red 92, Acid Blue 9, Disperse Yellow 121, Disperse Yellow 82, Disperse Yellow 83, Disperse Orange 11, Disperse Red 58, Disperse Blue 7, Direct Yellow 85, Direct Orange 8, Direct Red 9, Direct Blue 22, Direct Green 6, Solvent Yellow 44, Solvent Red 49, Solvent Blue 5, Solvent Green 7, etc.

These dyes can be used alone or in combination of two or more to adjust the color of the handwriting within the range that does not affect the performance of the color pencil lead. Furthermore, these dyes may be used in combination with other dyes. In addition, a coloring pigment obtained by coloring a resin with a dye can also be used.

Moreover, as a solid coloring agent, arbitrary pigments can also be used. In addition, ultrafine pigments or processed pigments can also be used.

However, in the case of combining a porous substrate and a solid colorant to form a porous core, the colorant solution obtained by dissolving the colorant in a solvent, such as a low-viscosity organic solvent, is impregnated with the body material and In the porous base material of the inorganic binder, the solvent is then removed, thereby facilitating the production (details will be described later). In the present invention, a low-viscosity organic solvent refers to a solvent with a viscosity of 20 mPa·s or less at 20°C. Therefore, the coloring agent used is preferably a dye, and more preferably a dye soluble in a low-viscosity organic solvent. Here, soluble means that 5 g or more can be dissolved in 100 g of a solvent at 20°C. In addition, in order to easily remove the solvent, it is preferable to use a low-viscosity organic solvent, and it is also preferable that the boiling point of the solvent is low. Specifically, it is preferably a solvent that volatilizes at a temperature at which the dye does not change color, more preferably a solvent that volatilizes at 100°C, and more preferably an aliphatic alcohol with 1 to 4 carbon atoms.

Regarding the content of the solid colorant relative to the total mass of the color pencil core, although the appropriate amount varies depending on the type, it is preferably 0.2-20% by mass, more preferably 0.3-18% by mass, and particularly preferably 0.5- 15% by mass.

The pores of the porous substrate of the color pencil lead of the present invention are filled with a non-volatile liquid. With the non-volatile liquid, the writing feeling when taking notes is improved.

In the present invention, the non-volatile liquid system refers to a liquid that is not easily volatile at room temperature. By using this non-volatile liquid, the time stability of the color pencil lead can be maintained at a high level. Specifically, the non-volatile liquid is preferably a liquid that does not volatilize at a temperature below 250°C. In addition, in order to be easily impregnated in the pores of the porous substrate, the less volatile liquid preferably has a low viscosity.

In addition, it is excellent in impregnation into the pores of the porous core, and it is not easy to impregnate the volatile liquid into the entire porous core uniformly and uniformly, so as to obtain a color pencil lead with excellent writing feeling or erasability. In other words, the surface tension of the non-volatile liquid is preferably 35 mN/m or less, more preferably 30 mN/m or less, and still more preferably 25 mN/m or less. Here, the surface tension can be measured by the method specified in JIS K2241 at a temperature of 25°C.

In addition, the dynamic viscosity of the non-volatile liquid is preferably 10000 mm ² /s or less, more preferably 1000 mm ² /s or less, and still more preferably 500 mm ² /s. In addition, the dynamic viscosity of the non-volatile liquid is preferably 1 mm ² /s or more, more preferably 5 mm ² /s or more, and still more preferably 10 mm ² /s or more. The reason is that if the dynamic viscosity of the non-volatile liquid is 10000 mm ² /s or less, the non-volatile liquid is easily impregnated in the entire porous core uniformly and without unevenness. In addition, if the dynamic viscosity of the non-volatile liquid is 1 mm ² /s or more, the non-volatile liquid is easily filled in the pores of the porous substrate. Here, the dynamic viscosity can be measured at a temperature of 25°C.

As specific examples of preferred non-volatile liquids, one may be selected from the group consisting of silicone oils, fluorine-based oils, mineral oils, vegetable oils, paraffins, polyol esters, and α-olefins. Among them, silicones are more preferred. oil. Since the viscosity change of silicone oil due to temperature is small and the stability is excellent, by using silicone oil as a non-volatile liquid, the color pencil lead is not easily affected by environmental changes or over time. In addition, it is used for color pencil lead In the case of a mechanical pencil, there is less corrosion to the parts such as the opening of the head end, the chuck, or the core container of the mechanical pencil containing metal materials. As the silicone oil, dimethyl silicone and methyl phenyl silicone are particularly preferred, and modified silicone can also be cited as the preferred silicone oil. In addition, it is preferably one that does not easily dissolve the solid colorant. By not easily dissolving the solid colorant, the solid colorant and the non-volatile liquid in the formed handwriting can be prevented from penetrating into the paper together, which can improve the erasability. In addition, as paraffin wax, polyol ester, or α-olefin, one having 14 or more carbon atoms is preferable.

The content of the non-volatile liquid relative to the total mass of the color pencil lead is preferably 4.5-20% by mass, more preferably 7-18% by mass, and particularly preferably 9.5-15% by mass.

The color pencil lead of the present invention can contain various additives within a range that does not affect its performance. The additives are preferably those contained in the color pencil lead in a solid state under normal temperature conditions, and more preferably those with a higher melting point. Specifically, the melting point is preferably 50°C or higher, more preferably 100°C or higher, and particularly preferably 200°C or higher. Examples of specific additives include phenol compounds, surfactants, preservatives, antifungal agents, resins, and the like.

These phenolic compounds also have the effect of improving the bending strength of the color pencil lead, and further suppress the decrease in strength under high temperature or high humidity environment, so it is preferable.

As such a phenol compound, one can cite: (i) Phenolic compounds with 1 phenol structure, such as 2-hydroxy-5-methyl-1,3-benzenedimethanol (melting point is about 128℃), etc.; (ii) Phenolic compounds with two phenol structures, such as Bisphenol A (melting point is about 158℃), 1,1-bis(4-hydroxyphenyl)-ethane, 1,1-bis(4-hydroxyphenyl)-propane, 1,1-bis(4-hydroxyphenyl)-n-butane, 1,1-bis(4-hydroxyphenyl)-n-pentane, 1,1-bis(4-hydroxyphenyl)-n-hexane, 1,1-bis(4-hydroxyphenyl)-2-ethylbutane, 1,1-bis(4-hydroxyphenyl)-2-methylpentane, 1,1-bis(4-hydroxyphenyl)-n-heptane, 1,1-bis(4-hydroxyphenyl)-2,3-dimethylpentane, 1,1-bis(4-hydroxyphenyl)-n-octane, 1,1-bis(4-hydroxyphenyl)-2-ethylhexane, 1,1-bis(4-hydroxyphenyl)-n-nonane, 1,1-bis(4-hydroxyphenyl)-n-decane, 1,1-bis(4-hydroxyphenyl)-3,7-dimethyloctane, 1,1-bis(4-hydroxyphenyl)-undecane, 1,1-bis(4-hydroxyphenyl)-n-dodecane, 1,1-bis(4-hydroxyphenyl)-tridecane, 1,1-bis(4-hydroxyphenyl)-tetradecane, 1,1-bis(4-hydroxyphenyl)-pentadecane, 1,1-bis(4-hydroxyphenyl)-n-hexadecane, 1,1-bis(4-hydroxyphenyl)-1-methylpropane, 2,2-bis(4'-hydroxyphenyl)-6,10,14-trimethylpentadecane 2,2-bis(4-hydroxyphenyl)propane, 2,2-bis(4-hydroxyphenyl)hexafluoropropane, 4,4'-(1-α-methyl-benzylidene) bisphenol, etc.; (iii) Phenolic compounds with 3 phenol structures, such as 4,4',4''-ethylene tri-2-methylphenol, 4,4',4''-ethylene triphenol (melting point is about 246℃) 4,4'-(1-phenylethane-1,1-diyl)bis(2-methylphenol), 1,1,1-tris(4-hydroxyphenyl)ethane, etc.; (iv) Phenolic compounds with 4 phenol structures, such as 4,4'-[4-(4-hydroxyphenyl)butane-2,2-diyl]diphenol and 4,4'-[3-(4-hydroxyphenyl)-1-methylpropylene]bis(2-methylphenol) 4,4'-Dihydroxytetraphenylmethane, etc. Furthermore, (v) a phenol compound having 5 or more phenol structures can also be used.

Generally speaking, the more phenol structure, the stronger the strength improvement effect of the color pencil lead. However, the phenol compound of (iii) or (iv) is easily contained in the color pencil lead, and the bending strength improvement effect of the color pencil lead is stronger, so it is better. good. Furthermore, it is more preferable to use the phenol compound of (iii), and it is especially preferable to use the phenol compound represented by the following formula (I).

(式中， R¹ 為氫或碳數1～3之烷基， R² 分別獨立地為碳數1～10之烷基， n分別獨立地表示0～2之數)[化1]

(In the formula, R ¹ is hydrogen or an alkyl group having 1 to 3 carbons, R ^{2 is} each independently an alkyl group having 1 to 10 carbons, and n each independently represents the number of 0 to 2)

Among the phenol compounds represented by the formula (I), 4,4',4''-ethylenetri-2-methylphenol or 4,4',4''-ethylenetriphenol is the most preferred.

Regarding the content of the phenol compound relative to the total mass of the pencil lead, although the appropriate amount varies depending on the type, it is preferably 0.1 to 10% by mass, more preferably 0.2 to 5% by mass.

The shape of the color pencil lead of the present invention is not particularly limited, and is usually a linear body with a circular cross section. Regarding its size, for example, as a color pencil lead for a mechanical pencil, the cross-sectional diameter is preferably 0.2 to 2.0 mm, more preferably 0.3 to 0.7 mm. In addition, the length is preferably 30 to 100 mm, more preferably 40 to 70 mm. In addition, when applied to a common colored pencil held by a support such as wood, the cross-sectional diameter is preferably 0.5 to 3.0 mm, more preferably 0.8 to 2.0 mm. Generally, color pencils are usually cut by inserting long-length color pencil cores into wood, etc. during the manufacturing process. Therefore, there is no restriction on the length, but it is usually 1,000 mm or less.

If the color pencil lead of the present invention uses a porous base material manufactured by firing, higher physical strength can be achieved. It is thought that the reason is that the solid colorant forms a uniform or uneven layer on the inner surface of the pores, or adheres to the inner surface of the pores in a block shape. The bending strength of the color pencil lead of the present invention is preferably 120 MPa or more. More preferably, it is 180 MPa or more. Here, the bending strength can be measured by the method specified in JIS S 6005: 2007.

＜Manufacturing method of colored pencil lead＞ The manufacturing method of the color pencil lead of the present invention is not particularly limited. However, it is better to manufacture by a method including the following steps: (a) The mixing step, which involves mixing the body material and the inorganic binder to prepare a mixture; (b) The extrusion step, which is to extrude the above-mentioned mixture to produce a linear molded product; (c) A firing step, which is firing the above-mentioned linear shaped article to produce a porous substrate; (d) An impregnation step, which involves contacting a solution or dispersion containing a colorant and a low-viscosity organic solvent with the porous substrate to be impregnated therein; (e) A drying step, which heats the porous substrate after the impregnation step to remove part or all of the low-viscosity organic solvent in the pores, thereby leaving the solid colorant in the pores Inside, and form voids, thereby forming a porous core; (f) A filling step, which involves bringing the porous core into contact with a non-volatile liquid, and filling the voids with the non-volatile liquid. This method will be described below.

(a) Mixing steps First, the constitutional material and the inorganic binder are kneaded to prepare a mixture. This mixture becomes the main component of the porous substrate. When mixing, organic solvents, plasticizers, etc. may be added as needed. The organic solvent used here is used to maintain the fluidity of the raw material mixture and make the mixture uniform, and is almost completely removed in the firing step, independent of the aforementioned low-viscosity organic solvents or non-volatile liquids.

(b) Extrusion step Next, the formed mixture is extrusion-molded to produce a linear molded product. The color pencil lead of the present invention is usually preferably formed into a linear body with a circular cross-sectional shape, and thus is formed into a linear molded product by extrusion molding.

(c) Firing step If necessary, the obtained linear molded product is dried and then fired to produce a porous base material. By firing, the organic solvent contained in the mixture is removed, and the body material and the inorganic binder are sintered to form a porous base material. The firing conditions are not particularly limited, as long as the materials are sintered to form a porous substrate. For example, the maximum temperature can be set to 650 to 1000°C. In addition, in order to avoid sudden temperature changes, the temperature at the time of firing may be increased continuously or stepwise. In this case, the temperature increase rate can be set to, for example, 10 to 100°C/hr. Furthermore, it is also preferable to perform firing at a certain temperature for a certain period of time, for example, about 0.5 to 2 hours after rising to a set temperature. Furthermore, these various conditions can be combined arbitrarily according to the objective. For example, it can be used: in an oxygen atmosphere, the temperature is raised from room temperature to 650°C at 10°C/hr, and then kept at 650°C for 1 hour for firing; or the temperature is raised from room temperature to 1000°C at 100°C/hr, and then kept at Conditions for firing at 1000°C for 1 hour.

(d) impregnation step After cooling the formed porous substrate as needed, the porous substrate is brought into contact with a solution or dispersion containing a colorant and a low-viscosity organic solvent. In this step, the colorant penetrates into the pores existing in the porous substrate. As the impregnation method, normal pressure impregnation or reduced pressure and pressure impregnation may be used.

The coloring agent content of the above-mentioned solution or dispersion is not particularly limited, but based on the total mass of the solution or dispersion, the concentration of the coloring agent is preferably 5-50% by mass, more preferably 5-45% by mass, especially Preferably it is 10-40 mass %. If it is more than this range, there is a tendency that the color rendering property does not increase corresponding to the amount of the coloring agent added, and the colorant may precipitate over time, and the stability of the solution or dispersion may decrease over time. . In addition, when using a coloring agent that can obtain sufficient color rendering even at a low concentration, or when erasability is more important (for example, when used as tailoring chalk, etc.), a lower concentration can be used The solution or dispersant. In this case, specifically, the concentration of the colorant is preferably 0.1-20% by mass, more preferably 0.5-10% by mass.

Furthermore, additives such as phenolic compounds, surfactants, preservatives, antifungal agents, or resins can be efficiently contained in the color pencil lead by introducing them into the colorant-containing solution or dispersion in advance, so it is preferred.

(e) Drying step Then, the porous substrate after the impregnation step is heated to remove part or all of the low-viscosity organic solvent contained in the solution or dispersion impregnated in the pores. As a result, the solid colorant remains, adsorbs, or adheres to the pores. In addition, the low-viscosity organic solvent is removed to form voids, thereby forming a porous core. The drying conditions are not particularly limited, as long as the low-viscosity organic solvent is sufficiently removed. For example, the drying is preferably performed at a temperature that is 0-10°C higher than the boiling point of the low-viscosity organic solvent.

(f) Filling step After cooling the formed porous core as needed, it is brought into contact with a non-volatile liquid. Through this step, the voids formed in the porous core are filled with a non-volatile liquid. The conditions at this time are not particularly limited. For example, a temperature of 60° C. and conditions of 6 hours to 12 hours can be adopted. When filling liquids that are not easily volatile, normal pressure impregnation or reduced pressure and pressure impregnation methods can be used.

Further, if necessary, washing and the like are performed to obtain the color pencil lead of the present invention. [Example]

The embodiments of the present invention are described below, but the present invention is not limited by them.

[Example 1] [Kneading step, extrusion step and firing step] Boron nitride 45 parts by mass Silicon oxide 45 parts by mass Polyvinyl alcohol 10 parts by mass Water 100 parts by mass A kneader or a three-roll mill is used to evaporate the moisture of the above-mentioned compound, and heat and knead the compound while extruding the obtained kneaded product with a specific diameter to obtain a linear molded product. The linear molded product was heated up to 600°C at a temperature increase rate of 10°C/hour in argon and kept for 5 hours. After that, it was set in an oxygen atmosphere, the temperature was raised at 100°C/hr, and it was fired at 900°C. Hours, a porous substrate with a porosity of 25% and a cross-sectional diameter of 0.55 mm was obtained.

[Impregnation step] Ethanol 70 parts by mass Yellow general dye 30 parts by mass (A salt-forming dye of basic dyes and organic acids, manufactured by Hodogaya Chemical Industry Co., Ltd., trade name: Aizen Spilon Yellow C-GNH) The above formulation was stirred at 60°C until it was uniformly mixed, thereby obtaining a colorant solution (1).

The porous substrate obtained in the firing step was immersed in the colorant solution (1) in a state of being heated to 60°C, and kept for 6 hours.

[Drying step] The porous substrate after the impregnation step is kept at 80° C. for 6 hours to evaporate and remove the low-viscosity organic solvent in the pores of the porous substrate, thereby obtaining a porous core.

[Filling step] Use silicone oil as a non-volatile liquid (1). Specifically, the porous core obtained in the drying step is immersed in silicone oil (manufactured by Shin-Etsu Chemical Co., Ltd., trade name: KF-96-50cs) in a state of being heated to 80°C, and kept 6 hours, thereby obtaining a color pencil lead. Then, the surface of the color pencil lead is washed with ethanol, and the excess non-volatile liquid adhering to the surface is removed, thereby obtaining a color pencil lead impregnated with 17.5% by mass of silicone oil.

The contents of the solid colorant and the non-volatile liquid of the color pencil core obtained in this way relative to the total mass of the color pencil core are 7.5% and 12.5%, respectively.

[Examples 2-17] Except for changing the colorant solution (1) or the non-volatile liquid (1) to those described in Table 1, the same method as in Example 1 was carried out to obtain a color pencil lead.

[Comparative Example 1] The porous substrate was obtained by the same method as in Example 1.

Then, while heating the following formulation to 70°C, it was stirred until it was uniformly mixed, thereby obtaining a colorant solution (5). Diethylene glycol monobenzyl ether 70 parts by mass Yellow general dye 30 parts by mass (A salt-forming dye of basic dyes and organic acids, manufactured by Hodogaya Chemical Industry Co., Ltd., trade name: Aizen Spilon Yellow C-GNH)

Then, the porous substrate was immersed in the colorant solution (5) in a state of being heated to 60°C, and kept for 6 hours to obtain a color pencil lead.

[Comparative Example 2] The porous substrate was obtained by the same method as in Example 1. Then, the colorant (1) was impregnated and dried by the same method as in Example 1, thereby obtaining a porous core. Then, the color pencil lead is made without going through the filling step. That is, the color pencil lead of Comparative Example 2 was not filled with a non-volatile liquid.

[Comparative Examples 3 and 4] The porous substrate was obtained by the same method as in Example 1. Then, the colorant (1) was impregnated and dried by the same method as in Example 1, thereby obtaining a porous core. Then, diethylene glycol monobenzyl ether (Comparative Example 3) or Isododecane (Comparative Example 4), which is a filling liquid for comparison, was filled instead of the non-volatile liquid (1) to obtain a color pencil lead.

[Evaluation] Use the following methods to evaluate the performance of the obtained color pencil lead.

[Evaluation method of initial erasure of handwriting (erasability 1)] The handwriting was erased according to the erasing ability test of the plastic eraser disclosed in JIS S 6050-2008, and the erasability at this time was evaluated by the sensory test. Furthermore, the existing product refers to the mechanical pencil lead "trade name: Neox Color Eno (yellow)" manufactured by Pilot Corporation Co., Ltd. A: Very good. B: Better than existing products. C: Same as existing products.

[Evaluation method of handwriting erasure after time (erasability 2)] After taking notes, place the note line at 25°C for 4 weeks, erase the handwriting according to the erasing ability test of plastic eraser disclosed in JIS S 6050-2008, and perform the erasability test at that time by the sensory test Make an evaluation. Furthermore, the existing product refers to the mechanical pencil lead "trade name: Neox Color Eno (yellow)" manufactured by Pilot Corporation Co., Ltd. A: Very good. B: Better than existing products. C: Same as existing products.

[Evaluation method of initial writing feeling (writing feeling 1)] Use colored pencil cores on high-quality paper (equivalent to note paper A specified in the old JIS P3201; 100% chemical pulp is used as raw material for papermaking, and the weighing range is 40～157 g/m ² , whiteness is 75.0% or more), write down notes, and evaluate the sense of writing at this time by a sensory test. A: Take notes very smoothly. B: Take notes smoothly. C: The brush feel is slightly rough and not smooth. D: The brush feel is rough and not smooth.

[Evaluation method of writing feeling after time (writing feeling 2)] After being manufactured, the sintered colored pencil lead placed in an environment of 25°C for 4 weeks was used to write notes on the above-mentioned high-quality paper, and the sense of writing at that time was evaluated by a sensory test. A: Take notes very smoothly. B: Take notes smoothly. C: The brush feel is slightly rough and not smooth. D: The brush feel is rough and not smooth.

[Evaluation method of bending strength] Using the method specified in JIS S 6005-2007, measure the average of the values obtained by measuring 10 pieces with a distance between the fulcrums of 20 mm.

[Table 1-1] Table 1-1 Example 1 2 3 4 5 6 7 8 9 10 Colorant solution No. (1) (2) (3) (4) (1) (4) (6) (1) (1) (1) Colorant Dye Y 30 30 30 30 30 30 30 Dye R 8 Dye B1 30 Dye B2 15 Phenolic compound Compound P1 Compound P2 Compound P3 Compound P4 Low viscosity organic solvent EtOH 70 92 70 70 85 70 70 70 PrOH 70 70 DEGMBE Non-volatile liquid SO1 SO1 SO1 SO1 OO OO SO1 SO2 PE LP Filling liquid (comparison) - - - - - - - - - - Evaluation Erasability 1 A A A A A A A A A A Erasability 2 A A A A A A A A A A Writing sense 1 A A A A B B A A B B Sense of writing 2 A A A A B B A A B B Flexural strength (MPa) 205 206 210 200 207 205 200 203 210 208 Overview A A A A B B A A B B

[Table 1-2] Table 1-2 Example Comparative example 11 12 13 14 15 16 17 1 2 3 4 Colorant solution No. (1) (1) (7) (8) (9) (10) (11) (5) (1) (1) (1) Colorant Dye Y 30 30 30 30 30 30 30 30 30 30 30 Dye R Dye B1 Dye B2 Phenolic compound Compound P1 5 2.5 Compound P2 5 Compound P3 5 Compound P4 5 Low viscosity organic solvent EtOH 70 70 65 67.5 65 65 65 70 70 70 PrOH DEGMBE 70 Non-volatile liquid HC TD SO1 SO1 SO1 SO1 SO1 - - - - Filling liquid (comparison) - - - - - - - - - DEGMBE ID Evaluation Erasability 1 A A A A A A A B A B A Erasability 2 A A A A A A A C A C A Writing sense 1 B B A A A A A A D A A Sense of writing 2 B B A A A A A A D A C Flexural strength (MPa) 205 209 230 225 220 215 225 173 205 178 201 Overview B B A A A A A C C C C In the table: Dye Y: Aizen Spilon Yellow C-GNH (basic dye and organic acid salt-forming dye, manufactured by Hodogaya Chemical Industry Co., Ltd.) Dye R: Aizen Spilon Red C-PH (basic dye and organic acid Salt-forming dye, manufactured by Hodogaya Chemical Industry Co., Ltd. Dye B1: Valifast Blue 1613 (basic dye and organic acid salt-forming dye, manufactured by Orient Chemical Industries Co., Ltd.) Dye B2: SBNBlue 570 (acid dye and organic amine) The salt-forming dye, manufactured by Baotogu Industry Co., Ltd.) Compound P1: 4,4',4''-ethylenetri-2-methylphenol Compound P2: Bisphenol A Compound P3: 2-hydroxy-5- Methyl-1,3-benzenedimethanol (manufactured by Honshu Chemical Co., Ltd., trade name: DML-PC) Compound P4: 4,4',4''-ethylene triphenol (manufactured by Honshu Chemical Co., Ltd., Trade name: TrisP HAP) EtOH: Ethanol PrOH: Isopropanol DEGMBE: Diethylene glycol monobenzyl ether (boiling point: 302°C) SO1: Silicone oil (manufactured by Shin-Etsu Chemical Co., Ltd., trade name: KF-96 -50cs, dimethyl silicone oil, surface tension: 20.8 N/m, dynamic viscosity 50 mm ² /s) SO2: silicone oil (manufactured by Shin-Etsu Chemical Co., Ltd., trade name: KF-50-100cs, Methyl phenyl silicone oil, surface tension: 21.8 N/m, dynamic viscosity 100 mm ² /s) OO: vegetable oil (olive oil, manufactured by Nisshin OilliO Group Co., Ltd., trade name: BOSCO olive oil, surface tension: 32 mN/m) PE: Polyol ester (manufactured by NOF Corporation, trade name: HR-170R) LP: Paraffin (liquid paraffin, manufactured by Sanguang Chemical Industry Co., Ltd., trade name: No.150S) HC: mineral oil (Petroleum-based hydrocarbons, manufactured by Standard Oil Co., Ltd., trade name: YUBASE 4) TD: α-olefin (1-tetradecene, manufactured by Idemitsu Kosan Co., Ltd., trade name: Linealene 14) ID: Isododecane (Manufactured by Maruzen Petroleum Co., Ltd., trade name: MARUKASOL R, boiling point: 177°C).

Claims (10)

A color pencil lead, characterized in that it is composed of a porous core and a non-volatile liquid, The above-mentioned porous core system is composed of a body material, an inorganic binder and a solid colorant, The non-volatile liquid system is filled in the pores of the porous core. Such as the color pencil lead of claim 1, wherein the non-volatile liquid is selected from the group consisting of silicone oil, fluorine-based oil, mineral oil, vegetable oil, paraffin, polyol ester and α-olefin. The color pencil lead of claim 1 or 2, wherein the solid colorant is a dye soluble in a low-viscosity organic solvent. The color pencil lead of any one of claims 1 to 3, wherein the above-mentioned body material is selected from the group consisting of titanium oxide, mica, talc, boron nitride, alumina and calcium carbonate. Such as the color pencil lead of any one of claims 1 to 4, wherein the inorganic binder is selected from clays, ceramics, zeolite, diatomaceous earth, activated clay, silica, aluminum phosphate, silicone resin and silicone rubber Group of composition. The color pencil lead of any one of claims 1 to 5, wherein the porosity of the porous core body is 5-40%. The color pencil lead of any one of claims 1 to 6, wherein the porous core is a fired core. The above-mentioned color pencil lead of any one of claims 1 to 7, which further contains a phenol compound. A manufacturing method of color pencil lead, which is characterized in that it comprises the following steps: (a) The mixing step, which involves mixing the body material and the inorganic binder to prepare a mixture; (b) The extrusion step, which is to extrude the above-mentioned mixture to produce a linear molded product; (c) A firing step, which is firing the above-mentioned linear shaped article to produce a porous substrate; (d) An impregnation step, which involves contacting a solution or dispersion containing a colorant and a low-viscosity organic solvent with the porous substrate to be impregnated therein; (e) A drying step, which heats the porous substrate after the impregnation step to remove part or all of the low-viscosity organic solvent in the pores, thereby leaving the solid colorant in the pores Inside, and form voids, thereby forming a porous core; (f) A filling step, which involves bringing the porous core into contact with a non-volatile liquid, and filling the voids with the non-volatile liquid. The method of claim 9, wherein the colorant does not change color at a temperature at which the low-viscosity organic solvent evaporates.