JPS632428Y2 - - Google Patents

Description

[Detailed explanation of the idea]

The present invention relates to a sintered colored pencil lead using boron nitride, which improves the color development of written characters. The so-called sintered type pencil lead, which is heat treated to firing or sintering temperature, has better strength and erasability than the so-called green lead type, which is simply solidified or dried as a heat treatment after extrusion molding. In view of this, various sintered type colored pencil leads have been studied in recent years. In particular, those that utilize the easy-to-peel property of boron nitride due to its layered structure are considered optimal as they provide a smooth writing feel. However, when writing, boron nitride adheres to the paper surface and the layer surface becomes the surface, which causes poor color development. In other words, methods for coloring sintered colored pencil leads are broadly divided into two methods: incorporating heat-resistant pigments into the porous sintered body, and allowing ink to exist in the pores of the porous sintered body. It is better to have color development when heat-resistant pigments are present, but it is actually necessary to use ink even if heat-resistant pigments are used together.As this ink hardly adheres to the surface of the boron nitride layer mentioned above, color development is insufficient. It's getting old. This idea was created in view of the above,
A colored pencil lead comprising a porous sintered body of clay containing boron nitride and an easily colored fibrous body, and an ink that exists in the pores of the porous sintered body and colors the fibrous body. It is something to do. The attached FIG. 1 is a schematic diagram for explaining the porous sintered body of the colored pencil lead of the present invention, and shows a part of the vertical cross section. In the figure, a rectangular portion with reference numeral 1 represents boron nitride, and a rod-shaped portion with reference numeral 2 represents a fibrous body. Further, among the irregularly shaped portions, hatched portions 3 represent clay, and unhatched portions 4 represent pores. Of course, the actual colored pencil lead has a structure that is impossible to illustrate, and the illustrated shape,
Dimensions, positional relationships, etc. are not absolute. Examples of the fiber body 2 include potassium titanate, silicon nitride, asbestos, alumina, silica, zirconia, and alumina silicate.
It is not only a porous sintered body that is a seed or a mixture of two or more types, or a structure such as a single crystal or a polycrystalline body, but also a porous sintered body whose surface has been organically treated to improve formability. It may also be one that has undergone appropriate modification, such as one that has had organic components removed during the heat treatment process to obtain it and has been given the ability to be easily colored with ink. As is already well known,
In terms of improving strength, it is preferable for the fiber body 2 to have a larger aspect ratio (length/diameter), and this is certainly one of the reasons why the fiber body 2 is used in the present invention, but this is not the essential idea of the present invention. The purpose of this is to color the fiber body 2 so that it functions as a coloring agent, and therefore there is no need for a particular aspect ratio. Rather, it is desirable to pay attention to the amount used. That is, the fibrous body 2 compensates for the drawbacks of the boron nitride 1 and needs to retain the advantages of the boron nitride 1. The weight ratio of boron nitride to 1 is preferably 3 to 50%, more preferably 5 to 30%. For example, the manufacturing process is as follows. Clay fibers selected from one or more of various types such as kaolin, montmorillonite, and bentonite, boron nitride, heat-resistant pigments used as necessary, excipients such as various resins, and plasticizers. A porous sintered body is obtained by kneading, extrusion molding, and heat treatment with a melting material, a stabilizing material, etc. This can be impregnated with ink. List some examples. [Example 1] (Colored pencil lead for 0.5 mm sharp pencil) Boron nitride 40 parts by weight Potassium titanate (manufactured by Otsuka Chemical Co., Ltd., trade name: Teismo D) 6 parts by weight Benite 30 parts by weight Polymethyl methacrylate 20 parts by weight Dioctyl phthalate 10 parts by weight Methyl ethyl ketone 100 parts by weight The above materials were thoroughly kneaded using three rolls heated at 80°C, dried at 130°C for 5 hours, and then ground in a pulverizer.
It was crushed to about mm diameter. The pulverized product is extruded into thin wires using an extrusion molding machine heated at 160°C, and after cutting into a predetermined length,
Heat treatment was performed up to 850°C in an air atmosphere. This was impregnated with red ink for oil-based ballpoint pens under reduced pressure of 10 ^-1 Torr to obtain a red pencil lead. [Examples 2 to 5] In Example 1, the amount of potassium titanate used was 2
Example 2 was prepared in the same manner as in Example 1 except that parts by weight were changed to 10 parts by weight, 14 parts by weight, and 18 parts by weight.
I gave it a rating of ~5. [Example 6, 7] In Example 1, potassium titanate was mixed with asbestos (imported and sold by A-Merck Japan Co., Ltd., and asbestos for Gooch crucibles).
Examples 6 and 7 were made in the same manner as in Example 1 except that silicon nitride (manufactured by Tateho Chemical Industry Co., Ltd., trade name: SNW #1) was used. [Comparative example] All Example 1 except that potassium titanate was not used and the amount of boron nitride used was 46 parts by weight.
The same procedure as above was used as a comparative example. The test results of the obtained colored pencil leads are shown in Table 1.

[Table] As mentioned above, the present invention maintains the smooth writing feel that is the advantage of boron nitride 1, and also
Not only can the strength be improved because of the fibrous body 2, but the fibrous body 2 colored by the ink existing in the pores, or the fibrous body 2 colored by the ink during writing, functions as a coloring material. , the color development, which is the most important factor for colored pencil lead, is improved, and its practical effects are enormous.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram for explaining the porous sintered body of the colored pencil lead of the present invention. 1...Boron nitride, 2...Fibrous body, 3...Clay,
4...Stomata.

Claims (1)

[Scope of utility model registration request] A colored pencil lead comprising a porous sintered body of clay containing boron nitride and an easily colored fibrous body, and an ink that exists in the pores of the porous sintered body and colors the fibrous body.