JPS5998176A - Manufacture of core of colored pencil - Google Patents

Abstract

PURPOSE:To improve the breaking strength of the core of a colored pencil, by preparing a metal-containing liquid which forms a part of white or colored material by heat-treatment, impregnating said liquid in the pores of a porous sintered material, heat-treating the material to form said white or colored material, and impregnating an ink to the sintered material. CONSTITUTION:A metal-containing liquid (preferably a silicon-containing liquid for a porous sintered material containing clay as a binder) capable of forming a compound (a metallic compound which does not lowers the color development in wirting) which becomes a part of white, colorless or colored material by heat- treatment, is impregnated into the pores of a porous sintered material (e.g. composed mainly of clay and boron nitride). The impregnated product is heat- treated to form said metallic compound, and impregnated with an ink. The heat- treatment is preferably coarried out at the highest possible temperature provided that there is no adverse effect to the porous sintered material. To prevent the loss of impregnated material from the pore of the porous sintered material caused by the rapid removal of the solvent, it is preferable to suppress the rate of temperature increase at a low level at the initial stage of the treatment, or to keep the material at a low temperature for a definite time interval.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improved method for manufacturing colored pencil leads by impregnating a porous sintered body with ink, and its purpose is to improve the breakage strength.

The so-called green core type, which is simply dried or solidified through heat treatment after extrusion molding, is better than the so-called sintered type, which is heat treated to a firing or sintering (hereinafter simply referred to as sintering) temperature. In view of the possibility of producing a pencil lead with excellent breakage strength, various sintered types of nine-color pencil lead have been studied in recent years, but K has not yet been developed to provide a product with sufficient strength.

If you want to simply improve the breakage strength, it is possible to do so by increasing the proportion of binder used or increasing the temperature of heat treatment, but this would make the disadvantages such as poor writing quality stronger. It is.

The present invention has been made based on the above, and
In a method for manufacturing a colored pencil lead by impregnating a multi-IL sintered body with ink, a metal-containing liquid that produces a white or colorless compound or a compound that becomes part of a coloring agent by heat treatment in the pores of the porous sintered body. The gist of this invention is a method for producing a colored pencil lead, which is characterized by impregnating the lead with a metal compound, heat-treating it to produce a white or colorless metal compound, or forming a part of the coloring material, and then impregnating it with an ink.

The porous sintered body that serves as the base material is made by extruding one or more types of binder and an extensible material such as a heat-resistant pigment or excipient material used as necessary into a thin wire shape, and then heat-treated. Well-known examples include those whose main components are at least clay and boron nitride, and those made from Hamura's boron compounds and other nitrides through heat treatment.

The ink is also stable over time.

For example, a variety of inks such as ballpoint pen ink and stamp ink can be used, as long as they do not dry.

Compounds that are white or colorless or part of coloring materials (
(hereinafter referred to as a single metal compound) is a metal compound that does not impair the coloring when written.

For example, it is possible to create a greenish color by using yellow ink and a blue metal compound, but it is preferable to create two colors only by ink.

From this point of view, it is preferable that both the porous sintered body and the metal compound have a visually white color.

Metal compounds are produced by heat treatment. That is, in impregnation with a metal-containing liquid that is carried out once or repeatedly, and in heat treatment.

It is produced by being oxidized, nitrided, carbonated, etc. depending on the heat treatment atmosphere, or by reduction, dehydration, etc. due to the heating itself.

1 as a metal-containing liquid that is the source of producing metal compounds.
For example, one or two of various metals such as silicon, aluminum, zinc, magnenium, titanium, carunium, and boron.
Although the liquid contains more than one species in an appropriate form, it is preferable to use one that produces a metal compound that is the same as or similar to the sintered composition of the porous sintered body.

For example, for a porous sintered body obtained using clay as a binding material, it is preferable that the porous sintered body contains silicon that produces silicon dioxide after heat treatment.

Also, heat treatment to produce metal compounds.

It does not have a negative effect on the porous sintered body itself (for example,
When boron nitride is used in a porous sintered body, generally good results can be obtained by treating it to as high a temperature as possible within the range (heat treatment at too high a temperature may cause structural destruction of the boron nitride). Furthermore, in the early stages of processing.

In order to prevent leakage of impregnation from the pores of the porous sintered body due to rapid removal of the liquid medium, it is preferable to reduce the temperature increase rate or maintain the temperature at a low temperature for a certain period of time.

Examples will be explained below.

[Example 1] (5) Preparation of porous sintered body 60 parts by weight of bentonite, 40 parts by weight of carbon nitride, 10 parts by weight of polymethyl methacrylate (excipient), 10 parts by weight of dioctyl phthalate (plasticizer), Methyl ethyl ketone (
Solvent) 100 parts by weight were thoroughly kneaded, extruded into a thin wire shape with the adjusted viscosity, and then sintered at up to 950°C to obtain 0.5 parts by weight.
A porous sintered body with a large diameter was obtained.

The porous sintered body prepared in step (3) was impregnated with a 30% ethanol solution of mixed ethyl polysilicate under a reduced pressure of 15 Torr for 30 minutes, maintained at 50°C for 5 hours in an oxidizing atmosphere, and then heated to 75°C. Heat treatment was performed at a constant rate of temperature increase over 8 hours to generate silicon dioxide in the pores of the porous sintered body.

[Example 2] The porous sintered body prepared in (5) of Example 1 was impregnated with a 50% aqueous solution of zinc acetate in the same manner as in Example 1, and then maintained at 70°C sVj in an oxidizing atmosphere.

Heat treated at a constant rate of temperature increase to 800℃ over 7 hours.

Zinc oxide was generated in the pores of the porous sintered body.

For comparison with those obtained in Examples 1 and 2, (
The porous sintered body itself obtained in b).

As a result of impregnating each with red ink for ballpoint pens and testing their properties, no differences were found in the color development of handwriting, or in terms of writing feel, and the breakage strength was measured according to JIS 56019. , respectively, in the aforementioned order.

16700g/Ki, 15500&/I1g, 14000
, 9/, a+le values were obtained.

As described above, according to the present invention, a colored pencil lead with excellent breakage strength can be obtained without substantially impairing other properties.

Patent applicant: Pentel Co., Ltd.

Claims (1)

[Claims] In a method of manufacturing a colored pencil lead by impregnating a porous sintered body with ink, heat treatment produces a compound that becomes colorless or a part of a coloring material in the pores of the porous sintered body. A method for producing a colored pencil lead, which comprises impregnating it with a metal-containing liquid, heat-treating it to produce a white or colorless metal compound or forming a part of a coloring material, and then impregnating it with ink.