JP2021070724A - Color pencil lead - Google Patents

Abstract

To provide a color pencil lead having excellent color development of a handwriting, an excellent feeling of writing and excellent storage stability.SOLUTION: There is provided a color pencil lead which comprises a porous core body comprising an extender material and an inorganic binder, a colorant filled in pores of the porous core body and a plasticizer selected from the group consisting of a carboxylic acid ester of a polyalkylene glycol and a carboxylic acid ester of an alcohol, wherein the plasticizer is an ester of a polyalkylene glycol containing an alkylene oxide unit having 2 to 4 carbon atoms and a carboxylic acid having 3 to 10 carbon atoms and the extender material is selected from the group consisting of titanium oxide, mica, talc, boron nitride, alumina and calcium carbonate.SELECTED DRAWING: None

Description

The present invention relates to a colored pencil lead. More specifically, the present invention relates to a colored pencil lead having excellent color development and erasability, smooth writing, and high physical strength.

Conventionally, colored pencil leads used for mechanical pencils and the like are mainly composed of a constitutional material such as boron nitride and a binder material such as clay, and if necessary, a kneaded product containing an organic polymer compound or the like is extruded and then extruded. An ink containing a colorant is impregnated into the pores of a white porous core obtained by firing at a high temperature. In order to improve the color development of such a colored pencil lead, it is conceivable to increase the amount of ink or colorant contained in the colored pencil lead.

However, if the porosity of the porous core is increased in order to increase the amount of ink to be impregnated, the strength of the core tends to decrease. Further, when the concentration of the colorant in the ink was increased, the colorant was precipitated by the volatilization of the solvent, and the color tone of the handwriting may be changed. Furthermore, the volatilization of the solvent tended to change the writing taste at the time of writing.

In addition, depending on the type of dye or solvent contained in the ink, the material or member holding the colored pencil lead may be denatured. Specifically, when oleic acid or the like was used as the solvent, parts such as mechanical pencils and holders that hold the colored pencil lead may be corroded over time.

Japanese Unexamined Patent Publication No. 51-63744 Japanese Unexamined Patent Publication No. 61-23667 Jikkai Sho 61-142835 Japanese Unexamined Patent Publication No. 07-041723

The present invention provides a colored pencil lead that is excellent in writing taste and color development of handwriting at the time of writing, and can maintain the writing taste and color development at a high level even after storage over time.

The colored pencil lead according to the present invention
A porous core body containing an extender and an inorganic binder,
Colored ink filled in the pores of the porous core and
Including,
The coloring ink is characterized by containing a coloring agent and a plasticizer selected from the group consisting of a carboxylic acid ester of a polyalkylene glycol and a carboxylic acid ester of an alcohol.

Further, the method for manufacturing a colored pencil lead according to the present invention is as follows.
(A) A kneading step of kneading an constitution material and an inorganic binder to prepare a mixture.
(B) An extrusion step of extruding the mixture to prepare a linear molded product.
(C) A firing step of firing the linear molded product to form a porous core, and (d) a colorant, a carboxylic acid ester of polyalkylene glycol, and a carboxylic acid of an alcohol on the porous core. An impregnation step of contacting and impregnating a colored ink containing a plasticizer selected from the group consisting of esters.
It is characterized by including.

The colored pencil lead according to the present invention has sufficient strength, and has excellent writing taste and color development. Further, the colored pencil lead according to the present invention is excellent in stability with time, and can maintain excellent writing taste and color development even after a lapse of time. At the same time, the handwriting formed by the colored pencil lead is also excellent in stability over time.

<Colored pencil lead>
The colored pencil lead according to the present invention includes a porous core body and colored ink filled in the pores of the porous core body. The following is a description of their configurations.

The porous core used for the colored pencil lead of the present invention contains an extender and an inorganic binder as main components. Examples of the constitutional material include white materials such as titanium oxide, mica, talc, boron nitride, alumina, and calcium carbonate, and colored materials such as molybdenum disulfide, tungsten disulfide, and graphite. It is desirable that the colored pencil lead according to the present invention forms a vivid handwriting. Further, when a fluorescent colorant is used as the colorant to form a fluorescent color handwriting, it is preferable that the color development is not hindered. Therefore, it is preferable to use a white constitutional material in order to form a high-brightness handwriting. In particular, it is preferable to use boron nitride because the constitutional material does not inhibit color development and the strength of the colored pencil lead is increased.

Examples of the inorganic binder include clays such as kaolinites, halosites, montmorillonites, sericites, and bentonites, ceramics, zeolites, diatomaceous earth, activated clay, silica, aluminum phosphate, silicone resin, and silicone rubber. Etc., and these can be used alone or in combination.

The blending ratio of the constitution material, which is the main component of the porous core body, and the inorganic binder is not particularly limited, but the mass ratio is preferably 9: 1 to 7: 3.

In the present invention, the porous core body includes a constitution material and an inorganic binder. Generally, a pencil lead is produced by molding a mixture of an extender and a binder and then firing it, but the same method can be applied to the present invention. That is, it can be produced by firing a mixture of an extender and an inorganic binder (details will be described later).

Further, a mixture containing an extender, an inorganic binder, an inorganic substance, a water-soluble resin, etc. is compressed at a high pressure and then immersed in water, a solvent, or the like to remove the inorganic substance, the water-soluble resin, or the like. It is also possible to manufacture a porous core body.

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 colored ink present in the pores is small, and the color development tends to be inferior or some resistance to brush strokes tends to occur. If it is more than 40%, the strength of the obtained porous core is obtained. Tends to decrease and break easily. The range of 5 to 40% is preferable because the color development property is good, the writing taste is smooth, and the strength of the colored pencil lead can be maintained.

The porosity of the porous core body 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 liquid is immersed in a liquid having good permeability (for example, benzyl alcohol), absorbed into the pores of the porous core until the liquid is saturated, and then the liquid mass (W2) is measured. Further, the porous core body is taken out from the liquid, the liquid adhering to the surface thereof is removed, and then the satiety mass (W3) is measured. Using these measured values, the porosity can be determined by the mathematical formula (1) shown below.

Porosity = (W3-W1) / (W3-W2) x 100 (1)

In the colored pencil lead according to the present invention, the pores of the porous core body described above are filled with colored ink. This coloring ink contains a coloring agent and a plasticizer as main components.

As the colorant, a dye or a pigment can be used. Further, a coloring pigment obtained by dyeing a resin with a dye can also be used. In general, the dye easily penetrates into the porous core body when made into a solution, so that the pencil core according to the present invention can be easily manufactured.

The dye that can be used in the present invention is not particularly limited, and examples thereof include general dyes and fluorescent dyes.

Examples of general dyes include oil-soluble dyes, acid dyes, basic dyes, and gold-containing dyes. Examples of the salt-forming dyes of these dyes include salt-forming dyes of acidic dyes and basic dyes, salt-forming dyes of basic dyes and organic acids, and salt-forming dyes of acidic dyes and organic amines. More specifically, Bali First Black 1802, Bali First Black 1805, Bali First Black 1807, Bali First Violet 1701, Bali First Violet 1704, Bali First Violet 1705, Bali First Blue 1601, Bali First Blue 1605, Bali First Blue 1613. , Bali First Blue 1621, Bali First Blue 1631, Bali First Red 1320, Bali First Red 1355, Bali First Red 1360, Bali First Yellow 1101, Bali First Yellow 1151, Nigrosin Base EXBP, Nigrosin Base EX, BASE OF BASIC DYES ROB- B, BASE OF BASIC DYES RO6GB, BASE OF BASIC DYES VPB-B, BASE OF BASIC DYES VB-B, BASE OF BASIC DYES MVB-3 (Orient Chemical Industry Co., Ltd.), Eisenspiron Black GMH-Special, Eisen Spiron Violet CRH, Eisen Spyron Blue GNH, Eisen Spyron Blue 2BNH, Eisen Spyron Blue C-RH, Eisen Spyron Red C-GH, Eisen Spyron Red C-BH, Eisen Spyron Yellow C-GNH, Eisen Spyron Yellow C-2GH, S.A. P. T. Blue 111, S.A. P. T. Blue GLSH-Special, S.M. P. T. Red 533, S.M. P. T. Orange 6, S.M. B. N. Violet 510, S.A. B. N. Yellow 530, S.A. R. C-BH (Hodogaya Chemical Co., Ltd.) and the like can be mentioned.

Examples of fluorescent dyes are Basic Yellow 1, 40, Basic Red 1, 1: 1, 13, Basic Violet 1, 7, 10, 11, 11: 1, Basic Orange 22, Basic Blue 7, Basic. Green 1, Acid Yellow 3, Acid Yellow 52, Acid Red 52, 77, 87, 92, Acid Blue 9, Disperse Yellow 121, 82, 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, and the like.

These dyes may be used alone or in combination of two or more in order to adjust the color of the handwriting within a range that does not affect the performance of the colored pencil lead. Further, other dyes may be used in combination with these dyes.

Moreover, any pigment can be used as a colorant. Further, ultrafine pigments, processed pigments and the like can also be used.

Further, a coloring pigment obtained by dyeing a resin with a dye can also be used. As the resin, any resin such as acrylic resin, styrene-acrylonitrile resin, styrene resin, nitrogen-containing resin, polyethylene resin, and polypropylene resin can be used. The dye to be combined with these resins can be selected from the above.

Considering the solubility of these resins in plasticizers, dispersibility and dispersion stability, dyeability with dyes, etc., it is preferable to use nitrogen-containing resin or styrene-acrylonitrile resin as the resin, and the nitrogen-containing resin is preferable. More preferred. As the nitrogen-containing resin, melamine resin, polyamide resin, urethane resin, urea resin, benzoquinamine resin and the like are preferably used, and from the viewpoint of dissolution stability with a plasticizer, melamine resin and polyamide resin are preferable, and melamine resin is more preferable. ..

Examples of coloring pigments include NKS-1000 series, MPI-500 series (manufactured by Nippon Fluorescent Chemical Co., Ltd.), FNP series, FM series (manufactured by Shinroihi Co., Ltd.) and the like.

These colored pigments may be used alone or in combination of two or more in order to adjust the color of the handwriting within a range that does not affect the performance of the colored pencil lead. Further, a dye may be used in combination with these coloring pigments.

Colored inks also contain plasticizers. This plasticizer has a function as a solvent or a dispersion medium. Generally, the dye is dissolved in the plasticizer, and the pigment is dispersed in the plasticizer.

The plasticizers used in the present invention may be (i) a carboxylic acid ester of a polyalkylene glycol (hereinafter, may be referred to as an ester (i)) and (ii) a carboxylic acid ester of an alcohol (hereinafter, referred to as an ester (ii)). Is selected from the group consisting of).

(I) Carboxylate ester of polyalkylene glycol The polyalkylene glycol constituting the ester (i) preferably contains 2 to 4 carbon atoms in the alkylene oxide unit. Specific examples thereof include homopolymers or copolymers containing ethylene oxide, propylene oxide, and butylene oxide as a unit. These alkylene oxides generally have a linear structure, but may have a branched structure. Of these, polyethylene glycol, polypropylene glycol, and poly (ethylene oxide / propylene oxide) copolymers are preferable because they are easily available.

Further, the carboxylic acid constituting the ester (i) may be a monocarboxylic acid or a polycarboxylic acid, and may be an aliphatic carboxylic acid or an aromatic carboxylic acid. Among such carboxylic acids, carboxylic acids having 3 to 10 carbon atoms are preferable. Specific examples thereof include propionic acid, butanoic acid, isobutane acid, n-pentanoic acid, 2-ethylbutyric acid, 2-ethylhexic acid, and decanoic acid.

Polyalkylene glycol has a plurality of hydroxyl groups at the terminals, and the hydroxyl groups react with the carboxyl group of the carboic acid to form an ester. Generally, all the hydroxyl groups of the polyalkylene glycol have reacted with the carboxyl group, but some hydroxyl groups may remain unreacted.

(Ii) Carboxylate ester of alcohol The alcohol constituting the ester (ii) may be a monoalcohol or a polyol, but an alcohol having 2 to 14 carbon atoms is preferable. The hydrocarbon group constituting the alcohol may be saturated or unsaturated, and may contain an oxy group −O− between the carbon atoms of the hydrocarbon chain. Specifically, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, n-hexyl alcohol, cyclohexyl alcohol, n-decyl alcohol, benzyl alcohol, ethoxyethyl alcohol, butoxyethyl alcohol, dibutoxyethoxyethyl alcohol. And so on.

The carboxylic acid constituting the ester (ii) may be an aliphatic carboxylic acid or an aromatic carboxylic acid. The aliphatic carboxylic acid preferably has 3 to 10 carbon atoms. Further, the carboxylic acid is preferably a polycarboxylic acid having a plurality of carboxyl groups. Specific examples thereof include malonic acid, fumaric acid, citric acid, acetyl citric acid, adipic acid, azelaic acid, and sebacic acid. The aromatic polycarboxylic acid preferably has 8 to 14 carbon atoms. Specific examples include phthalic acid, terephthalic acid, and trimellitic acid.

More specifically, (a) aliphatic polycarboxylic acid esters include diisodecyl adipate, di-n-octyl adipate, di-2-ethylhexyl azelaate, dibutyl sebacate, di-2-ethylhexyl sebacate, and the like. Examples of (b) aromatic polycarboxylic acid esters such as triethyl citrate and tributyl acetyl citrate include dimethyl phthalate, diethyl phthalate, dioctyl phthalate, dibenzyl phthalate, butyl benzyl phthalate, trimethyl trimellitic acid, and trimellitic acid. Examples thereof include triethyl acid, tripropyl trimellitic acid, tributyl trimellitic acid, trihexyl trimellitic acid and tri-n-octyl trimellitic acid.

The ester that can be used as a plasticizer in the present invention is generally commercially available. For example, as the ester (i), ADEKA Sizer RS-1000, RS-735, RS-700 and the like (trade names, all of which are ADEKA Corporation). As the ester (ii), ADEKA Sizers C-8, C-880, C-79, C810, C-9N, C-10 and the like (all trade names, manufactured by ADEKA Corporation) can be mentioned. Among the esters (ii), ADEKA Sizer RS-107 (dibutoxyethoxyethyl adipate) and the like (trade name, manufactured by ADEKA Corporation) can be mentioned as an alcohol containing an oxy group.

In the present invention, the above esters (i) and (ii) can be used as the plasticizer, and among these, the ester (i) and the ester (ii) whose alcohol contains an oxy group are Colored inks tend to have excellent solubility or stability. It is considered that this is due to the high compatibility between the oxy group contained in the ester and the dye.

When the ester (i) and the ester (ii) are used as the plasticizer, the mass average molecular weight is preferably 3,000 or less from the viewpoint of the solubility and dispersibility of the colorant and the storage stability of the colored pencil lead. More preferably, it is 000 or less.

The plasticizer used in the present invention preferably exhibits specific dissolving properties. Specifically, the SP value is preferably 8.0 or more and 11 or less. Here, the SP value is calculated as a mass-based weighted average of the SP values of each block constituting the plasticizer. When the plasticizer is a mixture of a plurality of types of compounds, the mass-based weighted average value of the SP values of each compound is used as the SP value of the plasticizer.

In the present invention, the plasticizer is preferably one that does not easily volatilize at room temperature. By using such a plasticizer, the stability of the colored pencil lead over time can be maintained at a high level. Specifically, the plasticizer is preferably a liquid that does not volatilize at 250 ° C. or lower. Further, the plasticizer preferably has a low viscosity in order to facilitate impregnation of the pores of the porous core body. Specifically, the viscosity of the plasticizer is preferably 1,000 mPa · s or less, more preferably 500 mPa · s or less, and even more preferably 100 mPa · s or less at 25 ° C. Here, the viscosity is measured by a method according to JIS-K-2283.

The concentration of the colorant in the coloring ink varies depending on the type of the colorant, but is preferably 5 to 60% by mass, more preferably 20 to 50% by mass, and 30 to 50% by mass. Is particularly preferable. The content of the colored ink with respect to the total mass of the colored pencil lead varies depending on the type, but is preferably 15 to 40% by mass, more preferably 20 to 30% by mass. If it is less than this range, the content of the colorant is small and the color development property tends to be inferior. If it is more than this range, the color development property tends not to be improved according to the amount of the colorant added. The stability of the solution or dispersion over time may decrease, such as the colorant precipitating over time.

The colored pencil lead according to the present invention may contain various additives as long as the performance is not affected. Specific examples of the additive include surfactants, preservatives, fungicides, resins and the like. These additives may be blended in the colored ink or in the porous core.

The shape of the colored pencil lead according to the present invention is not particularly limited, but is generally a linear body having a circular cross section. The size of the colored pencil lead for a mechanical pencil is preferably 0.2 to 2.0 mm and preferably 0.3 to 0.7 mm in cross-sectional diameter. The length is preferably 30 to 100 mm, more preferably 40 to 70 mm. Further, when applied to a general colored pencil held on a support such as wood, the cross-sectional diameter is preferably 0.5 to 3.0 mm, preferably 0.8 to 2.0 mm. .. A general colored pencil is often cut after sandwiching a long colored pencil core in wood or the like in the manufacturing process, so the length is not limited, but is generally 1,000 mm or less.

The colored pencil lead according to the present invention can achieve high physical strength by using a porous core body produced by firing. The bending strength of the colored pencil lead according to the present invention is preferably 120 MPa or more. It is more preferably 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 method for manufacturing the colored pencil lead according to the present invention is not particularly limited. However,
(A) A kneading step of kneading an constitution material and an inorganic binder to prepare a mixture.
(B) An extrusion step of extruding the mixture to prepare a linear molded product.
(C) A firing step of firing the linear molded product to form a porous core, and (d) a colorant, a carboxylic acid ester of polyalkylene glycol, and a carboxylic acid of an alcohol on the porous core. An impregnation step of contacting and impregnating a colored ink containing a plasticizer selected from the group consisting of esters.
It is preferable to produce by a method comprising. This method will be described below.

(A) Kneading step First, the constitutional material and the inorganic binder are kneaded to prepare a mixture. This mixture is the main component of the porous core. At the time of mixing, an organic solvent, a plasticizer, or the like can be added as needed. The plasticizer used here is for making the raw material mixture fluid and uniform, and is almost completely removed in the firing step, and is independent of the one used for the coloring ink. It was done.

(B) Extrusion process,
Subsequently, the formed mixture is extruded to prepare a linear molded product. Since the colored pencil lead according to the present invention is generally preferably formed into a linear body having a circular cross-sectional shape, it is formed into a linear molded product by extrusion molding.

(C) Baking Step The obtained linear molded product is dried as necessary and then fired to prepare a porous core body. By firing, the organic solvent contained in the above mixture is removed, and the constitution material and the inorganic binder are sintered to form a porous core body. The firing conditions are not particularly limited as long as the material is sintered to form a porous core body, and for example, the maximum temperature can be 650 to 1000 ° C. Further, in order to avoid a sudden temperature change, the temperature at the time of firing can be raised continuously or stepwise. The temperature rising rate in such a case can be, for example, 10 to 100 ° C./hr. It is also preferable to bake 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. Further, each of these conditions can be arbitrarily combined according to the purpose. For example, in an oxygen atmosphere, the temperature is raised from room temperature to 650 ° C. at 10 ° C./hr, and then the temperature is 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. Conditions such as firing at 1000 ° C. for 1 hour can be adopted.

(D) Impregnation Step After cooling the formed porous core body as necessary, the porous core body is brought into contact with the coloring ink. In this step, the colored ink permeates the pores existing in the porous core body. As a method of impregnation, normal pressure impregnation, reduced pressure, or pressure impregnation method can be used.

If necessary, further cleaning or the like can be performed to obtain a colored pencil lead according to the present invention.

Hereinafter, examples of the present invention will be described, but the present invention is not limited thereto.

[Examples 1 to 4, Comparative Example 1]
[Kneading process, extrusion process, and firing process]
Boron Nitride 45 parts by mass Silica 45 parts by mass Polyvinyl alcohol 10 parts by mass Water 100 parts by mass The above formulation is heat-kneaded with a kneader and three rolls while evaporating water, and the obtained kneaded product is extruded to a predetermined diameter. Molding was performed to obtain a linear molded product. In argon gas, this linear molded product was heated to 600 ° C. at a heating rate of 10 ° C./hour and held for 5 hours, then heated at 100 ° C./hr as an oxygen atmosphere, and heated at 900 ° C. for 1 hour. Firing was performed to obtain a porous core having a porosity of 25%.

The colorants and plasticizers shown in Table 1 were mixed and stirred at 60 ° C. until they were uniformly mixed to obtain colored inks.

The porous core obtained in the firing step is immersed in each colored ink in a state of being heated to 60 ° C., held for 6 hours, and then the colored ink remaining on the surface is wiped off to obtain a colored pencil core. Got

表中、
ピンク色蛍光顔料：ＭＰＩ−５０７Ｃ（商品名、日本蛍光化学株式会社製、メラミン・パラトルエンスルホンアミド・ホルマリン重縮合物（メラミン樹脂）と、ベーシックバイオレット１１：１（蛍光染料）と、ベーシックレッド １：１（蛍光染料）との混合物からなる蛍光顔料）
イエロー色蛍光顔料：ＭＰＩ−５０５Ｃ（商品名、日本蛍光化学株式会社製、メラミン・パラトルエンスルホンアミド・ホルマリン重縮合物（メラミン樹脂）と、ベーシックイエロー４０（蛍光染料）との混合物からなる蛍光顔料）
オレンジ色蛍光顔料：ＭＰＩ−５０４Ｃ（商品名、日本蛍光化学株式会社製、メラミン・パラトルエンスルホンアミド・ホルマリン重縮合物（メラミン樹脂）と、ベーシックイエロー４０（蛍光染料）と、ベーシックバイオレット１１：１（蛍光染料）と、ベーシックレッド １：１（蛍光染料）との混合物からなる蛍光顔料）

In the table,
Pink fluorescent pigment: MPI-507C (trade name, manufactured by Nippon Fluorescent Chemical Co., Ltd., melamine / paratoluenesulfonamide / formalin polycondensate (melamine resin), basic violet 11: 1 (fluorescent dye), basic red 1 1 (Fluorescent pigment consisting of a mixture with 1 (fluorescent dye))
Yellow fluorescent pigment: MPI-505C (trade name, manufactured by Nippon Fluorescent Chemical Co., Ltd., a fluorescent pigment consisting of a mixture of melamine, paratoluene sulfonamide, formalin polycondensate (melamine resin) and basic yellow 40 (fluorescent dye). )
Orange fluorescent pigment: MPI-504C (trade name, manufactured by Nippon Fluorescent Chemical Co., Ltd., melamine / paratoluenesulfonamide / formarin polycondensate (melamine resin), basic yellow 40 (fluorescent dye), basic violet 11: 1 (Fluorescent pigment) consisting of a mixture of (fluorescent dye) and basic red 1: 1 (fluorescent dye))

[Evaluation]
The performance of the obtained colored pencil lead was evaluated by the following method.

[Evaluation method of initial color development (color development 1)]
Using colored pencil leads, high-quality paper (corresponding to writing paper A specified in the former JIS P3201. Paper made from 100% chemical pulp, weighing range 40 to 157 g / m2, whiteness 75.0% or more) The color development state at that time was visually evaluated.
A: The color is very good and the fluorescent color is clearly visible.
B: The handwriting is thin and the color is slightly inferior, but the fluorescent color is visible.
C: The handwriting is thin, the color is inferior, and the fluorescent color is difficult to see.

[Evaluation method of initial writing taste (writing taste 1)]
Writing was performed on the high-quality paper using a colored pencil lead, and the writing taste at that time was evaluated by a sensory test.
A: Writing is possible very smoothly.
B: Writing is possible smoothly.
C: The brush feel is slightly rough and heavy.

[Evaluation method of color development after aging (color development 2)]
After production, a fired colored pencil lead left in an environment of 25 ° C. for 4 weeks was used to write on the woodfree paper, and the color development state at that time was visually evaluated.
A: The color is very good and the fluorescent color is clearly visible.
B: The handwriting is thin and the color is slightly inferior, but the fluorescent color is visible.
C: The handwriting is thin, the color is inferior, and the fluorescent color is difficult to see.

[Evaluation method of post-writing taste over time (writing taste 2)]
After production, writing was performed on the woodfree paper using a calcined colored pencil core left in an environment of 25 ° C. for 4 weeks, and the writing taste at that time was evaluated by a sensory test.
A: Writing is possible very smoothly.
B: Writing is possible smoothly.
C: The brush feel is slightly rough and heavy.

The results obtained are as shown in Table 2.

Further, when the colored pencil leads of Examples 1 to 4 were used for a mechanical pencil having a brass chuck and advancing the chuck to extend the pencil lead, the environment was 50 ° C. with the colored pencil lead held by the chuck. The chuck was not corroded even when left underneath for 8 weeks.

Claims (8)

A porous core body containing an extender and an inorganic binder,
Colored ink filled in the pores of the porous core and
Including,
A colored pencil lead, wherein the colored ink comprises a colorant and a plasticizer selected from the group consisting of a carboxylic acid ester of a polyalkylene glycol and a carboxylic acid ester of an alcohol. The colored pencil lead according to claim 1, wherein the plasticizer is an ester of a polyalkylene glycol composed of an alkylene oxide unit having 2 to 4 carbon atoms and a carboxylic acid having 3 to 10 carbon atoms. The colored pencil lead according to claim 1, wherein the plasticizer is an ester of an alcohol having 2 to 14 carbon atoms and an aliphatic carboxylic acid having 3 to 10 carbon atoms or an aromatic carboxylic acid having 8 to 14 carbon atoms. The colored pencil lead according to any one of claims 1 to 3, wherein the constitutional material is selected from the group consisting of titanium oxide, mica, talc, boron nitride, alumina, and calcium carbonate. The invention 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. Described colored pencil lead. The colored pencil lead according to any one of claims 1 to 5, wherein the porosity of the porous core is 5 to 40%. The colored pencil lead according to any one of claims 1 to 6, wherein the porous core is a fired core. (A) A kneading step of kneading an constitution material and an inorganic binder to prepare a mixture.
(B) An extrusion step of extruding the mixture to prepare a linear molded product.
(C) A firing step of calcining the linear molded product to prepare a porous core, and (d) a colorant, a carboxylic acid ester of polyalkylene glycol, and a carboxylic acid of an alcohol on the porous core. An impregnation step of contacting and impregnating a colored ink containing a plasticizer selected from the group consisting of esters.
A method for manufacturing a colored pencil lead, which comprises.