JPS647113B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an epoch-making colored lead core that is completely different from conventional colored lead cores and has various characteristics, and a method for manufacturing the same.

That is, the gist of the present invention is as follows.

1. (a) A porous sintered body that has a skeleton of a compound consisting of at least boron and nitrogen, has excellent lubricity and strong bending strength, and (b) Ink that is filled in the pores of the porous sintered body. A colored lead core characterized by being composed of.

2. After extruding at least a boron compound or a plastic composition containing a boron compound and boron into a fine wire lead core, the extruded core material is heated at high temperature in an atmosphere containing at least nitrogen, or nitrogen and hydrogen. By reacting, a porous sintered colored lead core material is created in which a compound consisting of boron and nitrogen is generated throughout the extruded core material, and this colored lead core material is further immersed in ink. A method for manufacturing colored lead cores characterized by filling ink into the pores of a porous sintered body to produce a completed core.

Conventional colored lead cores are made by kneading pigments, waxes, extenders, water-soluble pastes, etc., extrusion molding, and then drying the resulting core. The ink core is made by kneading graphite with clay or resin as a binding material.
After extrusion molding, the core is fired at high temperatures and impregnated with oil to form the finished core.

As mentioned above, the conventionally known colored lead lead and ink lead are created based on completely different technical ideas, and the performance of the ink lead is superior in terms of bending strength, writing feel, erasability, stability over time, etc. It's far superior. The reason for this is that while conventional colored lead cores use wax or resin as a binding material, ink cores are made of fired clay or resin and are used as a sinter. It has a bending strength that is 2 to 3 times or more than that of the previous one. Furthermore, because conventional colored lead cores use wax, they have a sticky feel and cannot be easily erased with an eraser. Furthermore, since waxes and water-soluble adhesives are used, they are easily affected by temperature and humidity, causing swelling in diameter and decreased bending strength, resulting in a lack of stability over time. On the other hand, the ink lead has a very good writing feel due to the swelling property of graphite, and the handwriting is made of graphite and a sintered body of fired clay or resin that adheres to the paper surface in fine powder form, so it is easy to erase with an eraser. In addition, the sintered body made of graphite and clay or resin is completely unaffected by temperature and humidity, so it is extremely stable and does not change over time.

As mentioned above, when comparing conventional colored lead lead and ink lead, the ink lead is significantly superior in terms of performance, so research is being conducted on a manufacturing method that involves firing the colored lead lead in the same way as the ink lead. has been done. For example, a pencil core made by mixing a refractory powder such as boron nitride with a caking agent such as clay, molding it, baking it and impregnating it with ink (Special Publication No. 49-34045), a heat-resistant pigment and boron nitride mixed with clay and/or Or, after adding resins, knead, mold,
Core material for colored pencils made by firing (Special Publication No. 10861, 1977),
A method in which fluorinated graphite or boron nitride, a heat-resistant pigment, and aqueous aluminum phosphate are kneaded, molded, and then fired at a temperature of 500°C or less (Japanese Patent Application Laid-open No. 51-97325), from boron nitride, clay, and an organic polymer compound. The kneaded product is extruded and then fired in an oxidizing atmosphere,
A method is known in which the organic polymer compound is removed and then the ink is impregnated (Japanese Patent Publication No. 51-41376).
The technical ideas of these fired colored lead cores have some things in common. This means that it uses boron nitride, and it is also made by hardening boron nitride with a sinterable binder that sinters when fired, such as clay, aluminum phosphate, or resin. It means that there is.

Boron nitride is a white powder in appearance, has a hexagonal layered structure like graphite, has a small hardness of 1 to 2 on the Mohs scale, and has excellent self-lubricating properties.
Furthermore, it is thermally and chemically stable, so it does not change even when fired at high temperatures, making it an excellent material for colored lead cores. However, due to thermal and chemical stability, it is difficult for boron nitride powder to sinter with each other, so as in the above-mentioned known example,
A sinterable binder is an essential condition for baking and hardening the boron nitride, and the amount and type of this sinterable binder determines the writing feel and strength of the colored lead core. In other words, it is not possible to take full advantage of boron nitride's softness with a Mohs hardness of 1 to 2, which is the most important property for fired colored lead cores, and its good lubricity while maintaining its strength; This was the current situation.

The inventor of the present invention has been involved in research on fired colored lead cores for many years, and as a result of repeated studies, the inventor discovered that boron nitride has excellent properties, which are important for fired colored lead cores, namely, a soft Mohs hardness of 1 to 2. They have discovered a method that can fully demonstrate this without compromising its good lubricity. In other words, the emphasis of the technical idea of the colored lead core of the present invention is to heat-treat the fine wire lead core-like material containing boron at high temperature in an atmosphere consisting of at least nitrogen or nitrogen and hydrogen to cause the boron and nitrogen to react. This is based on the idea that boron nitride is converted into boron nitride by the reaction, and the boron nitride produced by this reaction is produced throughout the fine wire lead core material. In addition, the colored lead core of the present invention reacts with boron and nitrogen at high temperatures, converts into boron nitride, and is directly sintered firmly. The technical idea is fundamentally different from that of fired colored lead cores, which require a binding material.

Next, a specific reaction example will be explained. For ease of understanding, when boron oxide is used as the thin wire lead core material and ammonia is used as the atmosphere at high temperature, the boron oxide changes according to the general formula B ₂ O ₃ + 2NH ₃ → 2BN + 3H ₂ O. . The by-product water in this case is released as steam, so the fine wire lead core material is theoretically converted to 100% boron nitride. To explain this reaction in more detail, the first reaction that occurs when boron oxide as a fine wire lead core material is heated in an ammonia atmosphere is the oxidation of the surface of the fine wire lead core material from room temperature to 300℃ or 400℃. This is an addition reaction between nitrogen and hydrogen, which are dissociated from boron and ammonia, and forms a film on the surface of a fine wire lead core material. This film protects the shape of the fine wire lead core material and also serves to prevent the fine wire lead core materials from fusing together. Next, 300℃ or 400℃
At temperatures above ℃, the reaction according to the above reaction formula occurs, water is diffused as steam, the fine wire lead core material becomes a porous structure, and the reaction between boron, oxygen, nitrogen and hydrogen progresses further inside. Although its exact structure is unknown, it is thought to pass through various intermediate compounds containing boron and nitrogen, and eventually transform into boron nitride. As mentioned above, a temperature of at least 300°C or higher is required to actually change into boron nitride, and preferably a temperature of 500°C or higher.

Boron compounds used in the present invention include boron oxides such as boric acid and their borates such as borax, boron halides such as boron trichloride, boron-nitrogen compounds such as boron nitride and boron amide, and various Examples include borosilicate and organic boron compounds, and these can be used alone or in combination. Furthermore, it is of course possible to use intermediate compounds generated in the various reaction steps of the present invention. Furthermore, when preparing a boron compound or a plastic composition containing a boron compound and boron, various additives can be optionally added in addition to the above-mentioned materials depending on the purpose. For example, hardness modifiers include ceramics such as silica and alumina; kneading aids and extrusion aids include wax, resin, water and organic solvents; colorants; and reaction accelerators.

In addition, a fine wire lead core material is created by extrusion molding the above plastic composition, and the fine wire lead core material is reacted at high temperature in a gas atmosphere so that the final composition is boron and nitrogen. The gas used at this time may be any gas containing nitrogen or nitrogen and hydrogen, such as ammonia, urea, melamine, hydrazine, ammonium chloride, and the like. At this time, it is also possible to use these substances in combination with an inert gas such as argon or helium as a transport medium. Further, baking may be performed in an oxidizing atmosphere as part of the process if necessary. In other words, when adding an organic polymer compound such as an extrusion aid, if it is fired in a non-oxidizing atmosphere, depending on the type of organic matter, it will remain as black carbon inside the colored lead core, which will cause the coloring of the ink as a colored lead core. This results in a hindrance. However, in the case of dark colored lead cores among colored lead cores, or when a mixture of black carbon and other colors is required, there is no need to remove the carbon remaining inside the lead core, so oxidation is required. No processing is necessary.

As a method for filling the porous sintered body of the present invention with ink, a method similar to that for filling an ink spool with oil can be used. In other words, ink can be filled into the pores by immersing a porous sintered body in ink, but depending on the characteristics of the ink, heating, depressurization,
Alternatively, it may be carried out under conditions such as pressurization.

The ink used in the present invention may be any ink that can be filled by the above-mentioned filling method, for example, colorants such as dyes and pigments are added to animal and vegetable oils, synthetic oils, alcohols, hydrocarbon oils, water, etc. Commonly used inks, such as stamp inks, which are manufactured by dissolving or dispersing them, or by further adding resins, surfactants, etc. as necessary.
Ballpoint pen ink, water-based writing ink, etc. can be used. Next, examples of the present invention will be described. However, % is weight %.

Example 1 After mixing powders of 60% boron oxide as a boron compound and 40% urea as a reaction accelerator, a fine wire lead core material was obtained by hot extrusion molding, and this fine wire lead core material was placed in an ammonia atmosphere. A white porous sintered body was obtained by raising the temperature to 1100°C and holding it for 5 hours. Analysis revealed that this white porous sintered body was formed from 43% boron and 55% nitrogen.
Bending strength according to JIS-S6019 measurement method is 21000g/
mm ² and was a colored lead core material with good lubrication performance. This white porous sintered body was immersed in blue felt-tip pen ink for 5 minutes at room temperature and pressure.
A time impregnation treatment was performed to fill the pores with blue felt-tip ink to create a finished blue colored lead lead.

Example 2 90% of the boron nitride intermediate with B _X N _Y O _Z structure as a boron compound was mixed with methylcellulose as an extrusion aid
After adding to the aqueous solution in which 10% of the
After adjusting the moisture content, extrusion molding is performed to obtain a fine wire lead core material.The fine wire lead core material is heated to 1500℃ in a nitrogen atmosphere and held for 2 hours to form a gray-black porous material containing black carbon. A quality sintered body was obtained. This gray-black porous sintered body is immersed in black ballpoint pen ink and impregnated for 2 hours at 60°C and 100mmHg to fill the pores with black ballpoint pen ink, resulting in a finished black colored lead core. It was created.

Example 3 The same fine wire lead core material as in Example 2 above was first heated to 600°C in an oxygen atmosphere and held for 5 hours.
Next, the temperature was raised to 1500℃ in a nitrogen atmosphere, and
A white porous sintered body was obtained by holding for a certain period of time. This white porous sintered body was immersed in black ballpoint pen ink and impregnated for 2 hours at 60°C and 100mmHg to fill the pores with black ballpoint pen ink to form a finished gray colored lead core. Created.

Example 4 Borax 50% and boron nitride 37 as boron compounds
% and 3% aluminum oxide as hardness modifier
, polyethylene glycol 10 as an extrusion aid
% was added to and mixed with an ethanol solution in which ethanol was dissolved, the ethanol was evaporated, and then heated and extruded to obtain a fine wire lead core material.The fine wire lead core material was heated to 800℃ in an ammonia atmosphere. A white porous sintered body was obtained by holding for a certain period of time. This white porous sintered body was immersed in red stamp ink and impregnated for 2 hours at 60° C. and 100 mmHg to fill the pores with red stamp ink to produce a completed red colored lead core.

Since the colored lead core material obtained in the above example is made of boron nitride, the softness and lubricity of boron nitride can be fully exhibited, resulting in smooth writing and soft handwriting. It is an excellent colored lead core. In addition, the bending strength is approximately 15,000 because boron and nitrogen are strongly sintered when they change into boron nitride.
~20,000 g/mm ² , which is 2 to 3 times stronger than conventional colored lead lead, and has good properties that are almost as good as ink lead.Furthermore, it has excellent erasability and is not affected by temperature or humidity, so it is stable over time. This is an innovative colored lead core with various features such as excellent properties.

As described above, the colored lead lead of the present invention has high bending strength, so it is ideal not only as a pencil lead but also as a colored lead lead for sharp pencils. In addition, the color of the handwriting is deep and clear, and colored lead cores of any hue can be easily obtained by selecting the hue of the ink, and intermediate hues are also possible by adjusting the hue of the colored lead core material. It also has the advantage of

Claims (1)

[Scope of Claims] 1. Consisting of (a) a porous sintered body whose skeleton is a compound consisting of at least boron and nitrogen, and (b) ink filled in the pores of the porous sintered body. Colored lead core. 2 At least a boron compound or a composition containing a boron compound and boron is extruded and reacted with nitrogen or a gas containing nitrogen and hydrogen at high temperature to form a porous sintered material with a skeleton of at least a compound consisting of boron and nitrogen. A method for producing a colored lead core, which is characterized by creating a compact and then filling the pores of this porous sintered body with ink.