JPS585952B2 - Iroenpitsushinno Seizouhou - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Conventional colored pencil leads are made by mixing and dispersing pigments, waxes, extenders, and water-soluble thickeners, molding the mixture, and drying the resultant mixture.

For this reason, it has extremely low structural strength compared to ink cores obtained by firing, and is sensitive to environmental conditions such as temperature and humidity, making it difficult to maintain stable physical properties.

Since the pigments used in brown pencil leads do not have the self-lubricating properties of graphite in black ink leads, wax must be used to provide lubricity and color spreadability.

Therefore, it is not erasable with an eraser, it is impossible to obtain heat resistance, and its characteristics as a writing instrument tend to change over time.

Furthermore, different pigments are mixed for each color, but since the chemical and physical properties of the pigments differ depending on the color, it is necessary to adjust the blending ratio for each pigment, making manufacturing complicated. Taste hardness, breakage strength, etc. cannot be obtained.

There is also a pencil lead that takes advantage of the lubricating properties of boron nitride and is made by mixing a binder such as clay with it, molding it, firing it, and then impregnating it with ink (Japanese Patent Publication No. 34045/1989). Since clay or the like is used as a binder, a firing temperature of 1000°C or higher is required.

However, the lubricity of boron nitride begins to deteriorate when heated above 700°C, and deteriorates significantly when the temperature exceeds 1000°C, so the lubricity cannot be used effectively.

The present invention has discovered that sufficient strength can be obtained by low-temperature firing by using aqueous aluminum phosphate as a binder, and by eliminating the above-mentioned drawbacks, it has strength and lubricity comparable to that of black ink core, and color This makes it possible to obtain a colored pencil lead that is erasable and has no difference in properties due to

The colored pencil lead manufacturing method of the present invention involves kneading at least one of graphite fluoride or boron nitride, a white extender pigment that can be easily dyed, and aqueous aluminum phosphate as a binder, and molding it into a desired shape. After that, it is heat-treated at a temperature of 500° C. or lower and impregnated with a dye of any color, and since no wax or the like is used, a colored pencil lead that is erasable with an eraser can be obtained.

Further, the lubricity of graphite fluoride or boron nitride provides an extremely good writing feel, and by using aqueous aluminum phosphate as a binder, sufficient strength can be obtained by firing at a low temperature of 300 to 500°C.

In addition, since a white pigment that is easily dyed is mixed, a large amount of dye is impregnated and a highly fresh color can be obtained.

Note that both the graphite fluoride and boron nitride have a particle size of 0.0.
It is a white fine powder with a size of 5 to 20 microns and has completely hexagonal crystals.

It also has a hardness as low as Mohs 1 to 2, and has extremely high lubricity similar to graphite.

Further, when fluorinated graphite is heated to a temperature above 500°C, its lubricity decreases, but it is extremely stable below 400°C.

Boron nitride loses its lubricity when heated above 700°C, and rapidly deteriorates when heated above 1000°C.

Therefore, the present invention maintains the heating temperature at 500°C or less,
Excellent lubricity similar to graphite provides a good brush feel.

As white pigments, 5 of the ordinary extender pigments for lakes are used.
Stable at temperatures below 00°C and easy to dye, such as titanium oxide, lithon, alumina white,
Calcium carbonate, white carbon, barium sulfate, talc, etc. can be used.

Further, as the aqueous aluminum phosphate used as a binder, monoaluminum phosphate "Feuerfest Binder 32" made in Germany or powder or liquid aluminum monophosphate made by Taki Hijo are suitable. Its specific gravity is 1.47, and its composition is 46 AI(H2Po4)3.
．． Section 5, the released P205 is P205 and A at section 2.06.
The molar ratio of 1203 is 3.2.

Such aqueous aluminum phosphate has a concentration of about 2
It can be diluted with water up to 0 times and is extremely stable.

In addition, aluminum hydroxide (AI(OH)3) is used as a hardening agent.
) or Al2(O
H) 5CI. When 2.4H20 is added, it hardens in about 18 hours even at room temperature, exhibits strong cohesive strength, and is stable against water and heat.

Therefore, in the present invention, after adding such a curing agent and curing at room temperature, heat treatment is performed at 500° C. or lower, thereby improving workability and increasing strength.

However, without adding a curing agent, it is also possible to knead and mold the material with the other raw materials mentioned above and heat treat it at 300 to 500C for about 2 hours. Through this heat treatment, it completely dehydrates and loses its hygroscopicity. Stability against water and heat is obtained as well as sufficient strength.

Moreover, since the structure is a porous body having extremely uniform micropores, it can be easily impregnated with a large amount of dye and dyed in a desired color.

Next, examples of the present invention will be described.

Example 1 Barium sulfate 20 weight fluorinated graphite 50 Aluminum phosphate 30 Water 100-150 After dispersing and mixing the above, adjusting the moisture content with two rolls and extruding into the desired shape, the mixture was heated to 200°C for 2 hours. Then, heat treatment is performed at 300° C. for 2 hours.

The rod-shaped white porous body thus obtained is impregnated with an aqueous or oil-based dye solution of any color in direct air or under pressure.

Example 2 Acid clay 20% Boron nitride 50% Aluminum phosphate 30% Water 100-150 After dispersing and mixing the above and molding in the same manner as in Example 1, 5%
A heat treatment at 00° C. for 2 hours is applied to impregnate the desired dye.

All of the colored pencil leads obtained as described above have extremely good writing quality, have high breakage strength, and can be erased with an eraser or the like.

In addition, the quality is stable and there are no problems such as differences in characteristics depending on the color.

Claims (1)

[Claims] 1. At least one of graphite fluoride or boron nitride, a white extender pigment that can be easily dyed with dye, and aqueous aluminum phosphate are kneaded and molded into a desired shape, and then heated to 500°C.
A method for producing colored pencil lead, which is characterized by subjecting it to heat treatment at the following temperature and impregnating it with a dye.