JP2002265846A - Calcined colored pencil lead and method for producing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a calcined colored pencil lead which can be inexpensively and easily produced, has excellent mechanical strength, excellent color development and a smooth writing property, and to provide a method for producing the same. SOLUTION: This calcined colored pencil lead is characterized by comprising a calcined lead body composed of alumina and an extender material which are obtained by impregnating a solution containing one or more kinds of inorganic polymers selected from aluminum inorganic polymers composed of a polyaluminoxane as a main chain into pores of a porous calcined lead body composed of at least an extender material and further calcining the impregnated calcined lead body and a colorant packed into the pores of the calcined lead body.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color pencil lead for a mechanical pencil and a wood axis color pencil lead. More specifically, while maintaining sufficient coloring and density of drawing lines,
The present invention relates to a fired colored pencil lead excellent in mechanical strength (bending strength, tensile strength, impact strength, etc.) and a method for producing the same.

[0002]

2. Description of the Related Art A conventional fired color pencil lead uses one or / and two or more kinds of inorganic substances such as clay as a binder, and further comprises a body material such as boron nitride, talc, mica, and, if necessary, heat resistance. The composition obtained by adding and mixing the pigment and the reaction accelerator is kneaded, and the kneaded product is extruded and formed into a porous fired core through heat treatment, and the coloring material such as ink is filled in the pores of the core. Let it be manufactured. At this time, the important characteristics required for the fired color pencil lead are high mechanical strength, good coloring properties of the drawn lines, and richness.

[0003] However, in the conventional fired color pencil lead,
The mechanical strength is not sufficient, and the density of the drawn line and the color development are not sufficient. For this reason, in order to meet the above demand, a core body capable of maintaining sufficient mechanical strength and increasing the porosity (pore porosity v / v) of the fired body to increase the amount of coloring material to be filled. Is desired.
Further, in the case of a fired core made of clay or the like which has been used as a conventional binder, the binder has a weak bonding force with a body material such as boron nitride, and the strength of the clay or the like itself is low. At present does not reach practical strength.
Furthermore, since natural clay contains impurities, the fired core body generally has a ground color, which has a problem in that it has a bad effect on the sharpness of drawing lines, especially the dull color of light-colored lines. Is the cause.

[0004] As a method of solving these problems, a perhydropolysilazane-containing liquid is impregnated into pores of a fired core made of a constitutional material, and heat-treated in an inert atmosphere such as a nitrogen atmosphere or an ammonia gas atmosphere. In addition, there has been proposed a fired pencil lead obtained by forming silicon nitride as a binder in a fired core, and then filling the pores of the core with ink (JP-A-8-48931). . According to this production method, a fired color pencil lead having excellent mechanical properties can be obtained while having sufficient coloring properties and drawing line density. However, in the above-mentioned manufacturing method, the core after firing may absorb moisture in the air in some cases, and there is a problem that mechanical strength such as initial bending strength cannot always be obtained with the core which has been deteriorated by moisture absorption. As a method for solving this problem, a heat treatment after filling the perhydropolysilazane is performed at a temperature of 1200 to 1200.
A production method at 1400 ° C. has been proposed (JP-A-20
00-95991).

However, when the heat treatment temperature is set at 1000
When the temperature is set to not less than ° C., there occurs a problem that the core is darkened due to carbonization of a trace amount of organic solvent or the like remaining in the pores of the core, and it is difficult to obtain an excellent color core having high saturation. In order to solve this, after filling with perhydropolysilazane, the temperature is set to 1000 in an inert atmosphere or an ammonia gas atmosphere.
There has been proposed a manufacturing method in which firing is performed at a temperature of 600 ° C. or higher, followed by firing at a temperature of 600 ° C. or higher in an oxidizing atmosphere (Japanese Patent Laid-Open No. 2000-2000).
However, it is difficult to completely remove the residual carbon even after firing in an oxidizing atmosphere since the firing process must be performed in an inert gas atmosphere or the like. In addition, perhydropolysilazane is a very expensive material, and has some disadvantages in its own stability such that hydrolysis easily proceeds when left in air.

[0006] Further, as a fired color pencil lead having a high saturation, at least pores of a fired lead body made of a body material are filled with a polysilazane-containing liquid and heat-treated in the air to produce silicon oxide as a binder. There has been proposed a baked color pencil lead obtained by filling ink into pores of a lead body and a method for producing the same (Japanese Patent Laid-Open No. 2000-17221). However, when the bonding material is silicon oxide, when the strength is about the same as silicon nitride, the amount of generated pores is small,
There is a problem that it is harder than the above-mentioned silicon nitride core in terms of writing taste and coloring power.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned drawbacks of the conventional baked colored pencil lead, which can be manufactured inexpensively and easily, and has excellent mechanical strength and particularly excellent color development and smoothness. An object of the present invention is to provide a fired colored pencil lead having a good writing taste and to provide a method for producing the same.

[0008]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies in order to solve the above-mentioned problems. As a result, an inorganic polymer group of aluminum having polyaluminoxane as a main chain is inexpensive and used as a raw material for a fired core. It can be easily manufactured and provided, and the fired core formed from the inorganic polymer group of aluminum has excellent mechanical strength, and can be obtained easily and stably. By doing so, alumina can be uniformly present in the entire fired core, and thereby, it is possible to provide an excellent white fired core and a fired core having excellent writing characteristics without variation in hardness, and Further, it has been found that the porosity of the fired core body can be maintained at an extremely high level, and that the density of the drawing line on the core body can be maintained at a high level. Than it was.

That is, the present invention provides the following (1) to (3)
The object has been achieved by providing the fired color pencil lead and the method for producing the same. (1) A solution containing at least one inorganic polymer selected from the group consisting of inorganic polymers of aluminum having polyaluminoxane as a main chain is impregnated in pores of a porous fired core made of at least a body material, and further fired. A fired pencil lead comprising: a fired core made of alumina and a body material; and a coloring material filled in pores of the fired core.

(2) A porous fired core made of the above-mentioned constitutional material is kneaded with a compounding composition containing an organic excipient and mixed with the constitutional material, extruded, and fired in a non-oxidizing atmosphere to carbonize the organic material. The fired colored pencil lead according to (1), wherein the fired pencil lead is a second fired core formed by further heating the first fired core in an oxidizing atmosphere to oxidize and remove the carbide.

(3) A compounded composition containing at least a body material and an organic excipient is kneaded, extruded, fired in a non-oxidizing atmosphere, and the fired fired core is further heated in an oxidizing atmosphere. To remove the carbides to form a porous fired core, and a solution containing at least one inorganic polymer selected from the group of inorganic polymers of aluminum having a polyaluminoxane as a main chain in the pores of the porous fired core. And further sintering in an oxidizing atmosphere to form a sintering core made of alumina and a body material, and filling the pores with a coloring material.

[0012]

Embodiments of the present invention will be described below in detail. The fired colored pencil lead according to the present invention is a solution containing at least one inorganic polymer selected from the inorganic polymer group of aluminum having a polyaluminoxane as a main chain in pores of a porous fired lead made of at least a body material. And a fired core made of alumina and a body material impregnated with and a coloring material filled in pores of the fired core.

The porous fired core of the fired colored pencil lead according to the present invention is obtained by kneading a body material and extruding the core into a core.
It is fired and provided as a porous fired body having open pores. As a constitutional material used for the porous fired core,
Usually, as long as it is used for a fired colored pencil lead, it is not particularly limited, and any of them can be used.
For example, a white base material such as boron nitride, talc, mica, or calcium carbonate, or a colored base material such as molybdenum disulfide may be used depending on the hue of a colored pencil.
Naturally, mixtures of these several types can also be used. Particularly preferred is boron nitride in view of its physical properties and shape. A heat-resistant pigment may be added to the porous fired core as needed.

The porous fired core is extruded and fired by adding an excipient to the body material. The shaping material may be inorganic or organic, and can be removed before firing, during firing or after firing, but in particular, kneading the body material, also acts as a binder during extrusion molding,
Organic excipients that can be removed by firing are preferred.

Examples of the organic excipient include thermoplastic resins such as polyvinyl chloride resin, chlorinated polyvinyl chloride resin, and polyvinyl alcohol; thermosetting resins such as furan resin, phenol resin, and epoxy resin; and lignin. ,
Natural polymer substances such as cellulose and tragacanth gum, petroleum asphalt, coal tar pitch, naphtha cracked pitch, pitches such as carbonized dry pitch of synthetic resin, and the like can be used. Naturally, mixtures of several kinds of these can also be used. Furthermore,
Water, dioctyl phthalate (DO
P), one or two or more plasticizers or solvents such as dibutyl phthalate (DBP), tricresyl phosphate (TCP), dioctyl adipate (DOA), propylene carbonate, alcohols, ketones, and esters are required. May be added according to the requirements.

In the fired colored pencil lead according to the present invention, the porous fired core made of at least the above-mentioned constitutional material is preferably made by kneading, extruding, and mixing a compounding composition containing an organic excipient in the above-mentioned constitutional material. The first fired core obtained by firing in an atmosphere and carbonizing the organic substance is preferably a second fired core formed by further heating in an oxidizing atmosphere to oxidize and remove the carbide.

Such a porous fired core is fired in a second step. That is, the above-mentioned composition composition as a material of the porous fired core is kneaded, extruded, and fired in a non-oxidizing atmosphere to carbonize the excipient. For example, after the above-mentioned composition is sufficiently kneaded with a Henschel mixer, a pressure kneader, a two-roll mill or the like, it is extruded into a fine wire by an extruder, and then in a nitrogen atmosphere or an inert gas atmosphere such as an argon gas. The first firing core of the carbonized excipient is obtained by baking in an organic excipient to sufficiently remove hydrogen, nitrogen, oxygen, water and the like from the organic excipient.

In the second fired core, hydrogen, oxygen, nitrogen, moisture and the like are sufficiently removed from the shaped material, and the first fired core of the carbonized shaped material is heated in an oxidizing atmosphere. The carbon binder is oxidized and removed. The porous fired core obtained from the second fired core by impregnation with a solution described later has fine and sufficient pores, is uniformly dispersed, and has sufficient mechanical strength. For this reason, the mechanical strength of the fired core is uniform and increased, and since the fired state is good, a fired core of extremely high color is obtained, and the writing quality does not adversely affect the coloring of drawing lines. Is obtained. Further, the coloring material is sufficiently filled in the pores of the core body.

In the fired colored pencil lead according to the present invention, the fired lead made of alumina and a body material is an inorganic polymer group of aluminum having a polyaluminoxane as a main chain in the pores of the porous fired core made of the body material. It is obtained by impregnating and firing a solution containing one or more inorganic polymers selected from the above. In particular, in the second fired core formed through the second step as described above, since the body material is highly oriented, it is selected from the inorganic polymer group of aluminum having polyaluminoxane as a main chain. When impregnated with a solution containing at least one inorganic polymer, the inorganic polymer group can be finely and uniformly present in the pores of the core. Then, the material subjected to the heat treatment in the oxidizing atmosphere results in a sintered core of high-strength alumina and a body material, and the mechanical strength is maintained uniformly. Further, the core body does not absorb moisture in the atmosphere and is not deteriorated. Therefore, mechanical strength such as bending strength of the core body is stably maintained.

In the fired colored pencil lead according to the present invention, the above-mentioned inorganic inorganic polymer group of aluminum having polyaluminoxane as a main chain is prepared by a general method such as a sol-gel method using an organic compound of aluminum or an inorganic compound of aluminum as a starting material. It is synthesized by various polymerization methods. Examples of the organic compound of aluminum include aluminum alkoxide, aluminum carboxylate, and the like, but are not necessarily limited to those shown. Also,
Examples of the inorganic compound of aluminum include aluminum nitrate, aluminum oxychloride, aluminum chloride, and the like, and further, hydrates thereof. Further, it is not always necessary to limit to these. These can be used alone or in combination of two or more kinds. However, they are determined in a form suitable for the polymerization method of the inorganic polymer. Among them, the inorganic compound of aluminum is inexpensive, and the inorganic polymer is inexpensive. Therefore, it is preferable for producing a baked color pencil lead.

In the synthesis of the above inorganic polymer group of aluminum having polyaluminoxane as a main chain, an organic compound which coordinates to a metal can be added and introduced into a side chain.
As such organic compounds, acetylacetone, ethyl acetoacetate, dimethylglyoxime, oxine, glycine, ethylenediamine, EDTA, bipyridine, phenanthroline, and other organic compounds widely known as ligands and chelating agents can be used. Although it is not particularly limited as long as it coordinates with aluminum, acetylacetone and ethyl acetoacetate which cause moderate steric hindrance are preferable. By introducing an organic compound which coordinates to these metals, the stability of the inorganic polymer group of aluminum having polyaluminoxane as a main chain can be enhanced, and the solubility in an organic solvent or the like can be controlled.

In order to improve and modify the physical properties of alumina, which is a binder obtained from the above-mentioned inorganic polymer group of aluminum, an inorganic polymer of another metal and / or an organic compound of another metal and / or Can be added. For example, polyzirconoxane which is an inorganic polymer group of zirconium for toughness, zirconium alkoxide etc. which is an organic compound of zirconium, or magnesium alkoxide which is an organic compound of magnesium for densification may be added. it can.
In addition, other organic compounds of titanium, organic compounds of silicon,
Polysiloxane, which is an inorganic polymer of silicon, can be used. These can be used alone or in combination of two or more.

In the fired colored pencil lead according to the present invention, the porous fired lead impregnated with a solution containing at least one inorganic polymer selected from the group consisting of the inorganic polymers of aluminum having polyaluminoxane as a main chain is used. By calcining in an oxidizing atmosphere, a calcined core body composed of alumina and a body material with alumina formed in the core body is obtained. In this case, since the calcined core body composed of alumina and the body material can be obtained without undergoing a calcining process in an inert atmosphere, it contains at least one selected from the group consisting of inorganic polymers of aluminum having polyaluminoxane as a main chain. An organic solvent or the like as a solution to be removed does not remain in the pores and is not carbonized, so that it does not take on a gray color and can form a very white fired core.

In the fired color pencil lead according to the present invention, ink is filled into the pores of the fired lead body composed of the above-mentioned alumina and a body material. The ink is a known colorant such as a dye or pigment dissolved and dispersed in water, animal and vegetable oils, synthetic oils, alcohols, hydrocarbon oils, and the like. And the like can be further added. In addition, printing inks, stamp inks, ballpoint pen inks, water-based writing instrument inks, and the like, which are generally used in production, can be used.

In addition, when a substance excellent in acid resistance and alkali resistance is selected as a constitutional material, the pigment is dissolved in an acid, an alkali, or the like, impregnated into a core, and further solidified in open pores. By impregnating the core with a liquid containing the precursor and causing a pigmentation reaction in the open pores, the pigment can be filled and colored.

Next, a method for producing a fired pencil lead according to the present invention, which is particularly preferred, will be described. First, after kneading and extruding a compounded composition containing at least the above constitutional material and an organic excipient, Baking in a non-oxidizing atmosphere. The non-oxidizing atmosphere is mainly an inert gas atmosphere, and specific examples include a nitrogen atmosphere and an argon gas atmosphere.

The fired core (first fired core) is further heated and fired in an oxidizing atmosphere to remove carbonized products.
Thus, the porous fired core (second fired core) is obtained. As the oxidizing atmosphere, ordinary air may be used,
Oxygen may be mixed to improve the removal efficiency.
It is also possible to use 00% oxygen. However, since boron nitride or the like as a constitutional material is easily oxidized when heated at a high temperature in a state of containing water, it is preferable that the atmosphere be sufficiently dry at this time. In addition, since the crystal form of talc changes when the firing temperature exceeds 700 ° C., it is preferable to fire at a temperature of 700 ° C. or lower.

The pores of the porous fired core are impregnated with a solution containing one or more inorganic polymers selected from the group consisting of the inorganic polymers of aluminum having polyaluminoxane as a main chain. The solution for containing the inorganic polymer group of aluminum is not particularly limited as long as it can sufficiently penetrate into the pores of the porous fired core. Specific solutions include:
Alcohols such as methanol, ethanol, propanol and butanol, ethylene oxide, ethylene glycol, tetraethylene glycol, toluene, xylene,
Organic solvents such as methyl ethyl ketone can be exemplified. In particular, the solution is preferably an organic solvent that does not cause hydrolysis or deterioration. The above solution is not limited to one type, and two or more types can be used as necessary.

As a method for impregnating the porous fired core, particularly the second fired core, with a solution containing at least one inorganic polymer selected from the group consisting of inorganic polymers of aluminum having polyaluminoxane as a main chain, The fired core can be immersed in the solution, and the solution can be impregnated into pores under conditions such as heating, decompression, and pressurization as needed. In this case, a solution containing one or more inorganic polymers selected from the inorganic polymer group of aluminum having the above-mentioned polyaluminoxane as a main chain has excellent stability and is hydrolyzed even when left in air for a long time. Since the changes such as deterioration and deterioration are extremely small, they can be dispersed very uniformly in the porous fired body without paying special attention unlike polysilazanes and the like.
The viscosity of the solution of the inorganic polymer group of aluminum having the polyaluminoxane as a main chain is 30 mPa · s (temperature: 25 mPa · s).
° C, E-type viscometer shear rate 192 s ^-1 ) or less,
It is preferably 15 mPa · s or less. If the viscosity of the solution exceeds 30 mPa · s, unevenness may occur during impregnation.

Next, the fired core impregnated with the above solution is further fired in an oxidizing atmosphere. In addition, in order to obtain a high-strength fired core, the above-described solution impregnation step and firing step may be repeatedly performed as necessary. In the firing in the oxidizing atmosphere, a white fired core can be obtained by maintaining the temperature at least at 200 ° C. or higher by selecting the type of the solution. For this reason, there is almost no need to consider the degradation temperature at which the body material is oxidized. For example, in the case of boron nitride exemplified as the above constitutional material, when the temperature exceeds 900 ° C., it is oxidized to boron oxide, and its lubricity is lost. Therefore, in this case, it is desirable to fire at a temperature of 900 ° C. or less, and in the method of manufacturing a fired color pencil lead according to the present invention,
The firing can be carried out with a sufficient margin at a temperature lower than that.

Finally, a coloring material is filled into the open pores of the above-mentioned fired core body composed of alumina and a body material to produce a fired pencil lead according to the present invention. These filling (impregnation) methods can be performed under conditions such as heating, decompression, and pressurization, and these steps may be repeated to increase the coloring concentration. In addition, it is also possible to color by a plurality of coloring methods. Further, it is also possible to impregnate the extra holes with oil or the like to improve the lubricity during writing.

In the fired colored pencil lead according to the present invention thus manufactured, since the fired lead composed of the alumina and the body material has pores capable of sufficiently absorbing the coloring material,
Excellent line density and coloring. In addition, since alumina made of the inorganic polymer group of aluminum having the above-mentioned polyaluminoxane as a main chain increases the mechanical strength of the fired core, as a result, the mechanical strength of the fired pencil lead itself is sufficient. In addition, a calcined core of alumina and a body made of an inorganic polymer group of aluminum can be easily provided at low cost.

[0033]

EXAMPLES Examples of the fired pencil lead according to the present invention and a method for producing the same will be described in more detail with reference to the following examples. However, the fired color pencil lead and the manufacturing method according to the present invention are not limited to the following examples.

Example 1 Composition A: Aluminum chloride hexahydrate 50 parts by mass Acetylacetone 42 parts by mass Triethylamine 30 parts by mass Ethanol 150 parts by mass The above composition A was stirred at 35 ° C. for 10 hours. After allowing the reaction to proceed sufficiently, fractional extraction and drying under reduced pressure were performed to recover polyaluminoxane A.

Composition B: 41.3 parts by mass of boron nitride 41.3 parts by mass of vinyl chloride resin 16.5 parts by mass of dioctyl phthalate (DOP) 0.9 parts by mass of zinc stearate 0.9 parts by mass of the above composition B with a Henschel mixer Mixed and dispersed,
After kneading with a pressure kneader and two rolls, the mixture is extruded into a thin wire and heat-treated at 180 ° C. in air in order to remove the remaining plasticizer. After the temperature was raised to 100 ° C., it was fired at 1000 ° C. to obtain a first fired core.

Next, the first fired core was heated and oxidized in air at a temperature of 700 ° C. to remove the remaining carbonized resin, thereby obtaining a white second fired core. The polyaluminoxane A-containing liquid was immersed in the second fired core at room temperature for one day, heated to a temperature of 600 ° C. in an oxidizing atmosphere, and fired at a temperature of 600 ° C. to obtain a fired core. Next, the polyaluminoxane A-containing liquid was immersed in the calcined core once again, and the temperature was raised to 700 ° C. in an oxidizing atmosphere.
The mixture was fired at ℃ to obtain a white third fired core having a diameter of 0.715 mm (a fired core made of alumina and a constitutional material).

Next, the above-mentioned third fired core was immersed in pink ink and left at a temperature of 70 ° C. for 24 hours. The surface of the third fired core filled with the pink ink is washed with alcohol,
A pink fired pencil lead was obtained.

Example 2 Compounding Composition C: Boron Nitride 30.0 parts by mass Talc 11.3 parts by mass Vinyl chloride resin 41.3 parts by mass Dioctyl phthalate (DOP) 16.5 parts by mass Zinc stearate 0.9 Parts by mass The above composition C was mixed and dispersed with a Henschel mixer.
After kneading with a pressure kneader and two rolls, the mixture is extruded into a thin wire and heated in air at a temperature of 180 ° C. to remove the remaining plasticizer. After the temperature was raised to 650 ° C., it was fired at 650 ° C. to obtain a first fired core.

Next, the first fired core was heated and oxidized in air at 650 ° C. to remove the remaining carbonized resin, thereby obtaining a white second fired core. The polyaluminoxane A-containing solution prepared in the same manner as in Example 1 was immersed in the second fired core at room temperature for one day, and then immersed in an oxidizing atmosphere for 6 days.
The temperature was raised to 00 ° C. and baked at a temperature of 600 ° C. to obtain a baked core. Next, the polyaluminoxane A-containing liquid is immersed in the fired core once more, and the temperature is 650 ° C. in an oxidizing atmosphere.
And fired at 650 ° C, 0.713m in diameter
m was obtained.

Next, the third fired core was immersed in pink ink and left at 70 ° C. for 24 hours. The surface of the third fired core filled with the pink ink was washed with alcohol to obtain a pink fired pencil lead.

(Comparative Example 1) After a second fired core similar to that of Example 1 was obtained, a perhydropolysilazane-containing liquid was immersed under the same conditions as in Example 1 and heated to 600 ° C. in a nitrogen atmosphere. After raising the temperature and firing at 600 ° C. to obtain a fired core, the fired core was once again impregnated with a liquid containing verhydropolysilazane, and heated to 1250 ° C. in a nitrogen atmosphere to obtain 12 cores.
After firing at 50 ° C., the temperature was lowered to 700 ° C., and firing was performed at 700 ° C. in air to obtain a third fired core having a diameter of 0.718 mm. Further, in the same manner as in Example 1, the above-mentioned third fired core was immersed in a pink ink and dyed to obtain a fired colored pencil lead.

(Comparative Example 2) After a second fired core similar to that of Example 1 was obtained, a liquid containing verhydropolysilazane was immersed in the same at room temperature for one day, and then heated to a temperature of 600 ° C in air. Then, it was fired at a temperature of 600 ° C. to obtain a fired core. Next, the liquid containing verhydropolysilazane is immersed again,
The temperature was raised to a temperature of 700 ° C. in air and fired at a temperature of 700 ° C. to obtain a third fired core having a diameter of 0.721 mm. Further, in the same manner as in Example 1, the above-mentioned third fired core was immersed in a pink ink and dyed to obtain a fired colored pencil lead.

(Comparative Example 3) The appearance and drawing line color of the third fired cores of Examples 1 and 2 and Comparative Examples 1 and 2 were used, and a pink pencil lead was used in accordance with JIS-S-6005-1989. Then, bending strength (MPa), writing taste by sensory evaluation, and coloring of drawing lines were evaluated. The results are shown in Table 1 below.

[0044]

[Table 1]

From the above results, the fired colored pencil cores of Examples 1 and 2 were prepared by using an inorganic polymer of aluminum having a polyaminoxane as a main chain in an inert atmosphere without deteriorating performance such as bending strength and writing taste. Since the third fired core is not easily fired, the drawn color of the third fired core is extremely white, and the color development of the fired pencil lead after dyeing is also extremely clear. Was. Further, by using an inorganic polymer of aluminum having a polyaluminoxane as a main chain, a calcined color pencil lead having a high bending strength and a smooth and good writing quality was obtained.

[0046]

As described above, the fired colored pencil lead according to the present invention is selected from a group of aluminum inorganic polymers having a polyaluminoxane as a main chain in at least the pores of a porous fired lead made of a body material. Since it is composed of a calcined core made of alumina and a body material impregnated with a solution containing one or more inorganic polymers and further calcined, and a coloring material filled in the pores of the calcined core, it is inexpensive and easy. It can be manufactured, and has excellent mechanical strength, particularly excellent color development and smooth writing.

Claims (3)

[Claims] An impregnated solution containing at least one inorganic polymer selected from a group of aluminum inorganic polymers having a polyaluminoxane as a main chain is impregnated in pores of a porous fired core made of at least a body material. A calcined pencil lead comprising a calcined core made of calcined alumina and a body material, and a coloring material filled in pores of the calcined core. 2. A porous fired core made of the above-mentioned constitutional material,
A kneaded composition comprising an organic excipient in the body material, extrusion molding, and firing in a non-oxidizing atmosphere to carbonize the organic material, and further heating the first fired core in an oxidizing atmosphere to form the carbide 2. The fired pencil lead according to claim 1, wherein said fired pencil lead is a second fired core formed by oxidative removal. 3. A kneaded composition comprising at least a body material and an organic excipient is kneaded, extruded and fired in a non-oxidizing atmosphere, and the fired fired core is further heated in an oxidizing atmosphere. A solution containing at least one inorganic polymer selected from the group consisting of inorganic polymers of aluminum having a polyaluminoxane as a main chain by removing carbides to form a porous fired core into pores of the porous fired core. A method for producing a fired pencil lead, characterized in that after impregnation, the fired core is further fired in an oxidizing atmosphere to form a fired core made of alumina and a body material, and the pores are filled with a coloring material.