Baked colored pencil core

Abstract

[Problem] To provide a color pencil lead which exhibits excellent physical strength, while having excellent writing erasability and smooth feel of writing. [Solution] 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

[Technical field]

[0001] The present invention relates to color pencil leads. More specifically, the present invention relates to color pencil leads that have excellent color development and erasability, a smooth writing feel, and high physical strength. [Background technology]

[0002] Conventionally, colored pencil leads used in mechanical pencils and the like are mainly composed of a filler such as boron nitride and a binder such as clay, and if necessary, a kneaded material containing an organic polymer compound is extruded and then baked at a high temperature to obtain a white porous base material, in which the pores are impregnated with ink containing a dye. When writing on paper with such colored pencil leads, the ink impregnated in the pores permeates the fibers of the paper, causing the dye and other coloring components to permeate the inside of the paper, which can reduce the erasability of the handwriting when erasing the handwriting with the colored pencil leads with an eraser. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 51-63744 [Patent Document 2] Japanese Patent Application Publication No. 61-23667 [Patent Document 3] Japanese Utility Model Application Publication No. 61-142835 [Patent Document 4] Japanese Patent Application Publication No. 07-041723 Summary of the Invention [Problem to be solved by the invention]

[0004] To provide a color pencil lead having excellent erasability of handwriting, smooth writing feel, and high physical strength. [Means for solving the problem]

[0005] The colored pencil lead according to the present invention is a porous core body comprising a filler, an inorganic binder, and a solid colorant; A low-volatility liquid filled in the pores of the porous core body; The present invention is characterized in that it comprises:

[0006] The method for producing colored pencil leads according to the present invention further comprises the steps of: (a) a kneading step of kneading an extender and an inorganic binder to prepare a mixture; (b) an extrusion step of extruding the mixture to produce a linear molded product; (c) a firing step of firing the linear molding to produce a porous substrate; (d) an impregnation step of contacting the porous substrate with a solution or dispersion containing a colorant and a low-viscosity organic solvent to impregnate the substrate; (e) a drying step of heating the porous substrate after the impregnation step to remove a part or all of the low-viscosity organic solvent in the pores, thereby leaving a solid colorant in the pores and forming voids, thereby forming a porous core; (f) a filling step of contacting the porous core body with a non-volatile liquid to fill the voids with the non-volatile liquid; The present invention is characterized in that it comprises: Effect of the Invention

[0007] When writing with the colored pencil core of the present invention, the colorant is prevented from penetrating into the paper, and when erasing with an eraser, the colorant present on the surface of the paper is easily removed, achieving excellent erasability. Furthermore, the impregnated low-volatility liquid provides a smooth writing experience, and the physical strength of the colored pencil core is increased, making it less likely to break. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] <Colored pencil core> The color pencil lead according to the present invention comprises a porous core body and a low-volatility liquid filled in the pores of the porous core body. The composition of the core body is described below.

[0009] The porous core used in the colored pencil lead of the present invention comprises a filler and an inorganic binder as main components. Examples of the filler include white ones such as titanium oxide, mica, talc, boron nitride, alumina, and calcium carbonate, and colored ones such as molybdenum disulfide, tungsten disulfide, and graphite. It is desirable for the colored pencil lead of the present invention to form vivid handwriting. In addition, when fluorescent colorants are used as colorants to form fluorescent handwriting, it is preferable for the filler not to inhibit the color development. For this reason, it is preferable to use a white filler in order to form handwriting with high brightness. In particular, it is preferable to use boron nitride, since the filler does not inhibit the color development and the strength of the colored pencil lead is increased.

[0010] Examples of the inorganic binder include clays such as kaolinites, halloysites, montmorillonites, sericites, and bentonites, ceramics, zeolites, diatomaceous earth, activated clay, silica, aluminum phosphate, silicone resins, and silicone rubbers, and these can be used alone or in combination.

[0011] The blending ratio of the filler material, which is the main component of the porous core, to the inorganic binder is not particularly limited, but is preferably 9:1 to 7:3 in mass ratio.

[0012] In the present invention, the solid colorant may be localized in a part of the porous substrate mainly composed of an extender or an inorganic binder, or may be uniformly dispersed throughout the entire porous substrate, but it is preferable that the solid colorant is localized in a part of the porous core. Specifically, it is preferable that the solid colorant is attached or adsorbed in the pores of the porous substrate. By having the colorant in a solid state in the porous core and in the final color pencil core, the colorant is prevented from penetrating into the inside of the paper during writing, and erasability is improved. Here, the solid colorant typically forms a layer or phase in the pores. That is, it is common for the solid colorant to form a uniform or non-uniform layer on the inner surface of the pores, or to be attached in a lump form. 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 included within the range in which the layer or phase does not have fluidity.

[0013] In the present invention, the porous core comprises a filler, an inorganic binder, and a solid colorant. Generally, pencil leads are manufactured by molding a mixture of a filler and a binder and then firing the molded mixture, and a similar method can be applied to the present invention. That is, pencil leads can be manufactured by firing a mixture of a filler and an inorganic binder and adsorbing or attaching a solid colorant to the formed porous fired base material (described in detail later). Alternatively, the filler, the inorganic binder, and the colorant may be mixed and fired, but in such a case, it is preferable to use a colorant with high heat resistance. On the other hand, in the former method, even a colorant with low heat resistance can be used.

[0014] Alternatively, a porous core can be produced by compressing under high pressure a mixture containing a filler, an inorganic binder, an inorganic substance, a water-soluble resin, and, if necessary, a solid colorant, and then immersing the mixture in water or a solvent to remove the inorganic substance, water-soluble resin, etc.

[0015] 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%, and more preferably in the range of 10 to 30%. If it is less than 5%, the amount of solid colorant and non-volatile liquid present in the pores will be small, and color development will tend to be poor and there will be some resistance to writing, while if it is more than 40%, the strength of the obtained porous core will tend to decrease and it will tend to be easily broken. If it is in the range of 5 to 40%, color development will be good, writing will be smooth, and the strength of the baked color pencil core can be maintained, which is preferable.

[0016] 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. Next, the porous core is immersed in a liquid with good permeability (e.g., benzyl alcohol) to allow the pores of the porous core to absorb the liquid until saturated, and then the mass in liquid (W2) is measured. Furthermore, the porous core is taken out of the liquid, and the liquid adhering to its surface is removed, and then the mass saturated with liquid (W3) is measured. Using these measured values, the porosity can be calculated according to the following mathematical formula (1).

[0017] Porosity = (W3-W1) / (W3-W2)×100 (1)

[0018] As the solid colorant, a dye or a pigment can be used. A colored pigment obtained by dyeing a resin with a dye can also be used. Although dyes generally have low heat resistance, they easily permeate the porous core when in solution, which makes it easier to manufacture the pencil lead according to the present invention. For this reason, it is preferable that the solid colorant is a dye.

[0019] The dyes that can be used in the present invention are not particularly limited, and include general dyes and fluorescent dyes.

[0020] Examples of common dyes include oil-soluble dyes, acid dyes, basic dyes, and metal-containing dyes. Examples of the salt-forming dyes of these dyes include 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 salt-forming dyes of basic dyes and resin acids. Among these, salt-forming dyes are preferred from the viewpoints of color development, permeability into the porous core when in solution, and dissolution stability when in solution. In addition, since they have high dissolution stability when in solution and can more strongly exhibit the effects of the present invention, those selected from the group consisting of salt-forming dyes of organic acids and basic dyes, salt-forming dyes of acid dyes and organic amines, and salt-forming dyes of basic dyes and resin acids are preferred, and salt-forming dyes of organic acids and basic dyes are most preferred.

[0021] More specifically, Balifast Black 1802, Balifast Black 1805, Balifast Black 1807, Balifast Violet 1701, Balifast Violet 1704, Balifast Violet 1705, Balifast Blue 1601, Balifast Blue 1605, Balifast Blue 1613, Balifast Blue 1621, Balifast Blue 1631, Balifast Red 1320, Balifast Red 1355, Balifast Red 1360, Balifast Yellow 1101, Balifast 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 Industry Co., Ltd.), Aizen Spiron Black GMH-Special, Aizen Spiron Violet C-RH, Aizen Spiron Blue Examples of dyes that can be used include GNH, Aizen Spiron Blue 2BNH, Aizen Spiron Blue C-RH, Aizen Spiron Red C-GH, Aizen Spiron Red C-BH, Aizen Spiron Red C-PH, Aizen Spiron Yellow C-GNH, Aizen Spiron Yellow C-2GH, SPT Blue 111, SPT Blue GLSH-Special, SPT Red 533, SPT Orange 6, SBN Violet 510, SBN Yellow 530, SBN Blue 570, and Spiron Red C-BH (Hodogaya Chemical Co., Ltd.).

[0022] 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 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, and the like.

[0023] These dyes may be used alone or in combination of two or more kinds to adjust the color of the writing, etc., as long as they do not affect the performance of the colored pencil lead. Furthermore, these dyes may be used in combination with other dyes. Also, color pigments in which resin is dyed with dyes can be used.

[0024] As the solid colorant, any pigment may be used. Ultrafine pigments and processed pigments may also be used.

[0025] However, when a porous core is formed by combining a solid colorant with a porous substrate, the porous substrate containing an extender and an inorganic binder is impregnated with a colorant solution in which the colorant is dissolved in a solvent, for example, a low-viscosity organic solvent, and then the solvent is removed, which facilitates production (described in detail later). In the present invention, the low-viscosity organic solvent refers to a solvent having a viscosity of 20 mPa·s or less at 20°C. For this reason, the colorant used is preferably a dye, and a dye soluble in a low-viscosity organic solvent is preferable. Here, soluble means that 5 g or more of the colorant is dissolved in 100 g of the solvent at 20°C. In order to facilitate removal of 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, a solvent that volatilizes at a temperature at which the dye does not discolor is preferable, and preferably a solvent that volatilizes at 100°C is preferable. More preferably, an aliphatic alcohol having 1 to 4 carbon atoms is preferable.

[0026] The content of the solid colorant relative to the total mass of the color pencil lead varies depending on the type of colorant, but is preferably 0.2 to 20 mass%, more preferably 0.3 to 18 mass%, and particularly preferably 0.5 to 15 mass%.

[0027] In the color pencil lead of the present invention, the pores of the porous substrate are filled with a non-volatile liquid, which improves the writing feel when writing.

[0028] In the present invention, the term "low-volatility liquid" refers to a liquid that does not easily volatilize at room temperature. By using such a low-volatility liquid, the temporal stability of the colored pencil lead can be maintained at a high level. Specifically, the low-volatility liquid is preferably a liquid that does not volatilize at 250° C. or lower. In addition, the low-volatility liquid preferably has a low viscosity in order to facilitate impregnation into the pores of the porous substrate.

[0029] Moreover, the surface tension of the non-volatile liquid is preferably 35 mN / m or less, more preferably 30 mN / m or less, and even more preferably 25 mN / m or less, because the non-volatile liquid has excellent impregnation into the pores of the porous core body and is evenly and uniformly impregnated throughout the porous core body to obtain a colored pencil lead with excellent writing feel and erasability. Here, the surface tension can be measured at a temperature of 25°C using the method specified in JIS K2241.

[0030] The kinetic viscosity of the non-volatile liquid is 10,000 mm 2 / s or less is preferable, and 1000 mm 2 / s or less is more preferable, and 500 mm 2 It is more preferable that the kinetic viscosity of the low-volatility liquid is 1 mm / s. 2 / s or more is preferable, and 5 mm 2 / s or more is preferable, and 10 mm 2 It is more preferable that the kinetic viscosity of the low-volatility liquid is 10,000 mm / s or more. 2If the kinetic viscosity of the non-volatile liquid is less than 1 mm / s, the non-volatile liquid can easily impregnate the entire porous core evenly and without unevenness. 2 This is because a kinetic viscosity of at least 1 / s makes it easy for the low-volatility liquid to fill the pores of the porous substrate. Here, the kinetic viscosity can be measured under the condition of a temperature of 25°C.

[0031] Specific examples of the preferred low-volatility liquid include those selected from the group consisting of silicone oil, fluorine-based oil, mineral oil, vegetable oil, paraffin, polyol ester, and α-olein, among which silicone oil is more preferred. Silicone oil has a small change in viscosity with temperature and is excellent in stability, so by using silicone oil as the low-volatility liquid, the colored pencil lead is less susceptible to environmental changes and time, and when the colored pencil lead is used in a mechanical pencil, it is less likely to corrode parts such as the tip opening, zipper, and lead storage tube of the mechanical pencil made of metal material. As silicone oil, dimethyl silicone and methylphenyl silicone are particularly preferred, and modified silicones can also be cited as preferred. In addition, it is preferable that the silicone oil is one that is less likely to dissolve the above-mentioned solid colorant. By being less likely to dissolve the solid colorant, the solid colorant is prevented from penetrating into the inside of the paper together with the low-volatility liquid in the formed handwriting, and the erasability can be improved. Moreover, the paraffin, polyol ester, or α-olefin preferably has 14 or more carbon atoms.

[0032] The content of the low-volatility liquid relative to the total mass of the color pencil lead is preferably 4.5 to 20 mass %, more preferably 7 to 18 mass %, and particularly preferably 9.5 to 15 mass %.

[0033] The colored pencil lead of the present invention may contain various additives to the extent that they do not affect the performance of the lead. These additives are preferably those that are contained in the colored pencil lead in a solid state under room temperature conditions, and those with a high melting point are more preferable. Specifically, those with a melting point of 50°C or higher are preferable, those with a melting point of 100°C or higher are more preferable, and those with a melting point of 200°C or higher are particularly preferable. Specific additives include phenolic compounds, surfactants, preservatives, antifungal agents, resins, etc.

[0034] Of these, phenol compounds are preferred because they improve the bending strength of the color pencil core and also have the effect of preventing a decrease in strength even in high temperature and high humidity environments.

[0035] Such phenolic compounds include: (i) Phenolic compounds having one phenol structure, e.g. 2-hydroxy-5-methyl-1,3-benzenedimethanol (melting point, approximately 128°C), etc. (ii) Phenolic compounds having two phenolic structures, e.g. Bisphenol A (melting point: approx. 158°C), 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)-n-undecane, 1,1-bis(4-hydroxyphenyl)-n-dodecane, 1,1-bis(4-hydroxyphenyl)-n-tridecane, 1,1-bis(4-hydroxyphenyl)-n-tetradecane, 1,1-bis(4-hydroxyphenyl)-n-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 having three phenolic structures, e.g. 4,4',4''-ethylidynetris-2-methylphenol, 4,4',4''-Ethylidinetriphenol (melting point: approx. 246°C) 4,4'-(1-phenylethane-1,1-diyl)bis(2-methylphenol), 1,1,1-tris(4-hydroxyphenyl)ethane, etc. (iv) Phenolic compounds having four phenolic structures, e.g. 4,4'-[4-(4-hydroxyphenyl)butane-2,2-diyl]diphenol and 4,4'-[3-(4-hydroxyphenyl)-1-methylpropylidene]bis(2-methylphenol) 4,4'-dihydroxytetraphenylmethane, etc. Furthermore, (v) a phenol compound having five or more phenol structures can also be used.

[0036] Generally, the more phenol structures there are, the greater the effect of improving the strength of the colored pencil lead, but the phenolic compounds of (iii) or (iv) are preferred because they are easy to incorporate into the colored pencil lead and have a large effect of improving the bending strength of the colored pencil lead. Furthermore, it is more preferred to use the phenolic compound of (iii), and among these, it is particularly preferred to use the phenolic compound represented by the following formula (I).

[0037] [ka] (In the formula, R 1 is hydrogen or an alkyl group having 1 to 3 carbon atoms, R 2 are each independently an alkyl group having 1 to 10 carbon atoms, Each n independently represents a number from 0 to 2.

[0038] Of the phenolic compounds represented by formula (I), 4,4',4''-ethylidinetris-2-methylphenol or 4,4',4''-ethylidinetriphenol is most preferred.

[0039] The content of the phenol compound relative to the total mass of the color pencil lead varies depending on the type of the compound, but is preferably 0.1 to 10% by mass, and more preferably 0.2 to 5% by mass.

[0040] The shape of the colored pencil lead according to the present invention is not particularly limited, but is generally a linear body with a circular cross section. For example, the size of the colored pencil lead for mechanical pencils is preferably 0.2 to 2.0 mm in cross-sectional diameter, and more preferably 0.3 to 0.7 mm. The length is preferably 30 to 100 mm, and more preferably 40 to 70 mm. When applied to general colored pencils held on a support such as wood, the cross-sectional diameter is preferably 0.5 to 3.0 mm, and more preferably 0.8 to 2.0 mm. In general colored pencils, since long colored pencil leads are often sandwiched between wood or the like during the manufacturing process and then cut, the length is not limited, but is generally 1,000 mm or less.

[0041] The colored pencil leads of the present invention can achieve high physical strength when a porous substrate produced by baking is used. This is believed to be because the solid colorant forms a uniform or non-uniform layer on the inner surface of the pores, or adheres in clumps. The bending strength of the colored pencil leads of the present invention is preferably 120 MPa or more, and more preferably 180 MPa or more. The bending strength can be measured by the method specified in JIS S 6005:2007.

[0042] <Manufacturing method of colored pencil cores> The method for producing the color pencil leads according to the present invention is not particularly limited. (a) a kneading step of kneading an extender and an inorganic binder to prepare a mixture; (b) an extrusion step of extruding the mixture to produce a linear molded product; (c) a firing step of firing the linear molding to produce a porous substrate; (d) an impregnation step of contacting the porous substrate with a solution or dispersion containing a colorant and a low-viscosity organic solvent to impregnate the substrate; (e) a drying step of heating the porous substrate after the impregnation step to remove a part or all of the low-viscosity organic solvent in the pores, thereby leaving a solid colorant in the pores and forming voids, thereby forming a porous core; (f) a filling step of contacting the porous core body with a non-volatile liquid to fill the voids with the non-volatile liquid; It is preferable to produce the compound by a method comprising the steps of: (a) preparing the compound by the method comprising the steps of:

[0043] (a) Mixing process First, the filler and inorganic binder are kneaded to prepare a mixture. This mixture is the main component of the porous substrate. When mixing, an organic solvent, a plasticizer, etc. can be added as necessary. The organic solvent used here is used to give the raw material mixture fluidity and make the mixture homogenous, and is almost completely removed in the firing process, and is separate from the low-viscosity organic solvent and the low-volatility liquid described above.

[0044] (b) an extrusion step; The mixture is then extruded to produce a linear product. Since the color pencil leads according to the present invention are preferably formed into linear bodies having a circular cross-sectional shape, the linear product is formed by extrusion.

[0045] (c) Firing process The obtained linear molding is dried as necessary and then fired to prepare a porous substrate. The organic solvent contained in the mixture is removed by firing, and the filler and inorganic binder are sintered to form a porous substrate. The firing conditions are not particularly limited as long as the materials are sintered to form a porous substrate, and the maximum temperature can be set to 650 to 1000°C, for example. In addition, in order to avoid a sudden temperature change, the temperature during firing can be increased continuously or stepwise. In such a case, the temperature increase rate can be set to, for example, 10 to 100°C / hr. In addition, it is also preferable to fire at a constant temperature for a certain period of time, for example, about 0.5 to 2 hours, after raising the temperature to a set temperature. Furthermore, these conditions can be arbitrarily combined according to the purpose. For example, firing conditions that can be used include increasing the temperature from room temperature to 650°C at a rate of 10°C / hr in an oxygen atmosphere, and then maintaining the temperature at 650°C for one hour, or increasing the temperature from room temperature to 1000°C at a rate of 100°C / hr, and then maintaining the temperature at 1000°C for one hour.

[0046] (d) Impregnation process After the formed porous substrate is cooled as necessary, the porous substrate is brought into contact with a solution or dispersion containing a colorant and a low-viscosity organic solvent. In this process, the colorant penetrates into the pores present in the porous substrate. As a method for impregnation, a normal pressure impregnation method or a reduced pressure or pressure impregnation method can be used.

[0047] The colorant content of the solution or dispersion is not particularly limited, but the concentration of the colorant is preferably 5 to 50 mass%, more preferably 5 to 45 mass%, and particularly preferably 10 to 40 mass%, based on the total mass of the solution or dispersion. If the amount is more than this range, the coloring property tends not to improve according to the amount of the colorant added, and the colorant may precipitate over time, which may reduce the stability of the solution or dispersion over time. In addition, when a colorant that can obtain sufficient coloring even at a low concentration is used, or when erasability is more important (for example, when applied as sewing chalk), a solution or dispersion with a lower concentration can be used. In such cases, specifically, the concentration of the colorant is preferably 0.1 to 20 mass%, more preferably 0.5 to 10 mass%.

[0048] Additives such as phenolic compounds, surfactants, preservatives, antifungal agents, or resins are preferably incorporated into the solution or dispersion containing the colorant, since these can be efficiently incorporated into the color pencil lead.

[0049] (e) Drying process Subsequently, 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 in the pores and is adsorbed or attached. Then, voids are formed by removing the low-viscosity organic solvent, and a porous core is formed. The drying conditions are not particularly limited as long as the low-viscosity organic solvent is sufficiently removed, but it is preferable to dry at a temperature of +0 to +10°C relative to the boiling point of the low-viscosity organic solvent, for example.

[0050] (f) Filling process If necessary, the formed porous core is cooled and then contacted with a non-volatile liquid. This process fills the voids formed in the porous core with the non-volatile liquid. The conditions for this process are not particularly limited, but for example, a temperature of 60°C for 6 to 12 hours can be used. For filling with the non-volatile liquid, a normal pressure impregnation method or a reduced pressure / pressure impregnation method can be used.

[0051] If necessary, further washing or the like can be carried out to obtain the color pencil lead according to the present invention. EXAMPLES

[0052] Examples of the present invention will be described below, but the present invention is not limited thereto.

[0053] [Example 1] [Kneading process, extrusion process, and baking process] Boron nitride 45 parts by weight Silica 45 parts by weight Polyvinyl alcohol 10 parts by weight 100 parts by mass of water The mixture was heated and kneaded in a kneader and a triple roll while evaporating water, and the kneaded product was extruded to a specified diameter to obtain a linear molded product. The linear molded product was heated to 600°C at a heating rate of 10°C / hour in argon gas and held for 5 hours, then heated at 100°C / hour in an oxygen atmosphere and fired at 900°C for 1 hour to obtain a porous substrate with a porosity of 25% and a cross-sectional diameter of 0.55 mm.

[0054] [Impregnation process] Ethyl alcohol 70 parts by weight General yellow dye 30 parts by mass (A salt-forming dye made from basic dyes and organic acids, manufactured by Hodogaya Chemical Co., Ltd., product name: Aizenspiron Yellow C-GNH) The above mixture was stirred at 60° C. until uniformly mixed to obtain a colorant solution (1).

[0055] The porous substrate obtained in the baking step was immersed in the colorant solution (1) heated to 60° C. and held for 6 hours.

[0056] [Drying process] The porous substrate that had been subjected to the impregnation step was held 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.

[0057] [Filling process] Silicone oil was used as the non-volatile liquid (1). Specifically, the porous core obtained in the drying process was immersed in silicone oil (manufactured by Shin-Etsu Chemical Co., Ltd., product name: KF-96-50cs) heated to 80°C and held for 6 hours to obtain a colored pencil lead. Next, the surface of the colored pencil lead was washed with ethanol to remove excess non-volatile liquid attached to the surface, and a colored pencil lead impregnated with 17.5% by mass of silicone oil was obtained.

[0058] The contents of the solid colorant and the non-volatile liquid relative to the total mass of the colored pencil core thus obtained were 7.5% and 12.5%, respectively.

[0059] [Examples 2 to 17] Colored pencil leads were obtained in the same manner as in Example 1, except that the colorant solution (1) or the non-volatile liquid (1) was changed to one shown in Table 1.

[0060] [Comparative Example 1] A porous substrate was obtained in the same manner as in Example 1.

[0061] Next, the following mixture was heated to 70° C. and stirred until uniformly mixed to obtain a colorant solution (5). Diethylene glycol monobenzyl ether 70 parts by mass General yellow dye 30 parts by mass (A salt-forming dye made from basic dyes and organic acids, manufactured by Hodogaya Chemical Co., Ltd., product name: Aizenspiron Yellow C-GNH)

[0062] Next, the porous substrate was immersed in the colorant solution (5) heated to 60° C. and held for 6 hours to obtain color pencil leads.

[0063] [Comparative Example 2] A porous substrate was obtained in the same manner as in Example 1. Further, impregnation with colorant (1) and drying were performed in the same manner as in Example 1 to obtain a porous core body. Then, a colored pencil lead was produced without going through a filling step. In other words, the colored pencil lead of Comparative Example 2 is not filled with a non-volatile liquid.

[0064] [Comparative Examples 3 and 4] A porous substrate was obtained in the same manner as in Example 1. Furthermore, impregnation with colorant (1) and drying were performed in the same manner as in Example 1 to obtain a porous core body. Furthermore, instead of the low-volatility liquid (1), diethylene glycol monobenzyl ether (Comparative Example 3) or isododecane (Comparative Example 4) was filled as a filling liquid for comparison to obtain a color pencil lead.

[0065] [evaluation] The performance of the resulting colored pencil leads was evaluated by the following method.

[0066] [Evaluation method for initial handwriting erasability (erasability 1)] The handwriting was erased according to the erasing ability test for plastic erasers disclosed in JIS S 6050-2008, and the erasability was evaluated by a sensory test. The existing product refers to a mechanical pencil lead manufactured by Pilot Corporation, "Product name: Neox Color Eno (yellow)." A: Very good. B: Better than existing products. C: Same as existing product.

[0067] [Evaluation method for erasability of handwriting after aging (erasability 2)] After writing, the written lines were left for 4 weeks in a 25℃ environment, and the handwriting was erased in accordance with the erasability test for plastic erasers disclosed in JIS S 6050-2008, and the erasability at that time was evaluated by a sensory test. The existing product refers to a mechanical pencil lead manufactured by Pilot Corporation, "Product name: Neox Color Eno (yellow)". A: Very good. B: Better than existing products. C: Same as existing product.

[0068] [Evaluation method for initial writing feel (writing feel 1)] Using the colored pencil leads, writing was done on high-quality paper (equivalent to writing paper A as specified in the old JIS P3201. Made from 100% chemical pulp, with a basis weight range of 40 to 157 g / m2 and a whiteness of 75.0% or more), and the writing feel was evaluated by a sensory test. A: It writes very smoothly. B: Smooth writing possible. C: The writing feel is somewhat rough and heavy. D: The writing feel is rough and heavy.

[0069] [Method for evaluating writing feel after aging (writing feel 2)] After production, the baked color pencil leads were left to stand for 4 weeks in a 25° C. environment, and then used to write on the above-mentioned wood-free paper, and the writing feel at that time was evaluated by a sensory test. A: It writes very smoothly. B: Smooth writing possible. C: The writing feel is somewhat rough and heavy. D: The writing feel is rough and heavy.

[0070] [Evaluation method for bending strength] The average value was measured for 10 pieces with a support distance of 20 mm using the method specified in JIS S 6005-2007.

[0071] [Table 1-1]

[0072] [Table 1-2] In the table: Dye Y: Aizenspiron Yellow C-GNH (a salt-forming dye made from a basic dye and an organic acid, manufactured by Hodogaya Chemical Co., Ltd.) Dye R: Aizenspiron Red C-PH (a salt-forming dye made from a basic dye and an organic acid, manufactured by Hodogaya Chemical Co., Ltd.) Dye B1: Varifast Blue 1613 (a salt-forming dye made from a basic dye and an organic acid, manufactured by Orient Chemical Industries Co., Ltd.) Dye B2: SBN Blue 570 (a salt-forming dye made from acid dye and organic amine, manufactured by Hodogaya Kogyo Co., Ltd.) Compound P1: 4,4',4''-ethylidynetris-2-methylphenol Compound P2: Bisphenol A Compound P3: 2-hydroxy-5-methyl-1,3-benzenedimethanol (manufactured by Honshu Chemical Co., Ltd., product name: DML-PC) Compound P4: 4,4',4''-ethylidynetriphenol (manufactured by Honshu Chemical Co., Ltd., trade name: TrisP HAP) EtOH: Ethyl alcohol PrOH: Isopropyl alcohol DEGMBE: Diethylene glycol monobenzyl ether (boiling point: 302°C) SO1: Silicone oil (Shin-Etsu Chemical Co., Ltd., product name: KF-96-50cs, dimethyl silicone oil, surface tension: 20.8 N / m, dynamic viscosity: 50 mm 2 / s) SO2: Silicone oil (Shin-Etsu Chemical Co., Ltd., product name: KF-50-100cs, methylphenyl silicone oil, surface tension: 21.8 N / m, kinetic viscosity: 100 mm 2 / s) OO: Vegetable oil (olive oil, manufactured by Nisshin Oillio Group, Ltd., product name: BOSCO Olive Oil. Surface tension: 32 mN / m) PE: Polyol ester (NOF Corporation, product name: HR-170R) LP: Paraffin (liquid paraffin, manufactured by Sanko Chemical Industry Co., Ltd., product name: No. 150S) HC: Mineral oil (petroleum-based hydrocarbons, manufactured by Standard Oil Co., Ltd., product name: YUBASE 4) TD: α-olefin (1-tetradecene, manufactured by Idemitsu Kosan Co., Ltd., product name: Linearene 14) ID: Isododecane (Maruzen Oil Co., Ltd., product name: Marukasol R, boiling point: 177°C)

Claims

1. a porous core body comprising a filler, an inorganic binder, and a solid colorant; a low-volatility liquid that is a liquid that does not volatilize at 250° C. or lower and is filled in the pores of the porous core body; A phenol compound having 1 to 4 phenol structures; A colored pencil lead comprising:

2. 2. The colored pencil lead according to claim 1, wherein the low-volatility liquid is selected from the group consisting of silicone oil, fluorine-based oil, mineral oil, vegetable oil, paraffin, polyol ester, and α-olefin.

3. 3. The color pencil lead according to claim 1, wherein the solid colorant is a dye soluble in a low-viscosity organic solvent.

4. The colored pencil lead according to any one of claims 1 to 3, wherein the filler is selected from the group consisting of titanium oxide, mica, talc, boron nitride, alumina, and calcium carbonate.

5. The colored pencil lead according to any one of claims 1 to 4, wherein the inorganic binder is selected from the group consisting of clays, ceramics, zeolites, diatomaceous earth, activated clay, silica, aluminum phosphate, silicone resin, and silicone rubber.

6. The color pencil lead according to any one of claims 1 to 5, wherein the porosity of the porous core body is 5 to 40%.

7. The colored pencil lead according to any one of claims 1 to 6, wherein the porous lead is a fired lead.

8. (a) a kneading step of kneading an extender and an inorganic binder to prepare a mixture; (b) an extrusion step of extruding the mixture to produce a linear molded product; (c) a firing step of firing the linear molding to produce a porous substrate; (d) an impregnation step of contacting the porous substrate with a solution or dispersion containing a colorant, a low-viscosity organic solvent, and a phenolic compound having 1 to 4 phenol structures, thereby impregnating the porous substrate; (e) a drying step of heating the porous substrate after the impregnation step to remove a part or all of the viscous organic solvent in the pores, thereby leaving a solid colorant in the pores and forming voids, thereby forming a porous core; (f) a filling step of contacting the porous core with a non-volatile liquid that does not volatilize at 250° C. or less to fill the voids with the non-volatile liquid; A method for producing colored pencil leads, comprising:

9. The method of claim 8 , wherein the colorant does not change color at a temperature at which the low viscosity organic solvent volatilizes.

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