JPH066690B2 - Color pencil lead manufacturing method - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing a non-fired colored pencil lead used in mechanical pencils, pencils and the like.

(Prior art) Using a resin such as nitrocellulose as a binder, a body material such as talc or potassium titanate fiber, a coloring material that is appropriately used to make various colors, and a lubricant for improving writing. In general, a non-baking type colored pencil lead is manufactured by kneading and extruding a material, and a solvent and the like used as necessary.

Here, as the lubricant, natural and artificial fats and oils such as carnauba wax and polyethylene wax, stearic acid,
Stearate salts such as calcium stearate and aluminum stearate are used.

(Problems to be Solved by the Invention) When a lubricant is used, it is possible to obtain the effect of smoothing the writing and often improving the density, but the bending strength is significantly reduced.

Therefore, it is an object of the present invention to provide a method for producing a colored pencil lead having a smooth writing quality and an improved darkness, while suppressing a decrease in bending strength.

(Means for Solving the Problems) The present invention provides a method for producing a non-baking type colored pencil lead obtained by kneading and extruding a binder, a coloring material, an extender and a lubricant as at least the main materials. Therefore, the gist is a method for producing a colored pencil lead, wherein lithium myristate is used as at least a part of the lubricant.

The details will be described below.

As the binder, polyvinyl chloride, polyethylene, polystyrene, AS resin, ABS resin, nitrocellulose,
Acetyl cellulose, a phenol resin, polyvinyl alcohol, etc. can be illustrated, and among these, a cellulose resin, especially nitrocellulose is preferable. Examples of the extender include talc, mica, boron nitride, potassium titanate fiber, silicon nitride fiber, asbestos fiber, magnesium oxysulfate fiber, and among these, potassium titanate fiber and magnesium oxysulfate fiber. Is preferred. The colorant may be inorganic or organic, but organic pigments are preferred. And lithium myristate is used with these.
Other materials having a lubricant function, such as stearate, can be used together with this lithium myristate.

One or two or more of each of the above materials, and a solvent or the like used as necessary is used as a compounding material. Here, the proportion of lithium myristate used in the blended material is preferably 5 to 70% by weight, and more preferably 8 to 50% by weight, based on the total amount excluding the solvent such as solvent that is removed midway.

Mix the ingredients uniformly with a roll or kneader,
After extrusion molding, the product is trimmed to a predetermined size to obtain a product. On the way, air-drying or air-drying treatment at a temperature not so high may be performed if necessary.

(Function) Lithium myristate is a colorless scaly crystal, and it is considered that the decrease in bending strength can be suppressed because of its good dispersion distribution in the core and good adhesiveness with the binder. Further, since it has the above-mentioned crystallinity, it is considered that it easily breaks down and is fixed on the paper surface by a small shearing force at the time of writing, in order to give smoothness and richness of writing.

(Example) Hereinafter, "parts" means "parts by weight".

[Example 1] Nitrocellulose 30 parts Red lake pigment 20 parts Potassium titanate fiber (average particle size 0.5 μm, average particle length 150 μm) 35 parts Lithium myristate 15 parts Methyl ethyl ketone 150 parts The above materials are homogenized by three rolls. After kneading and adjusting the solvent content, the mixture was extruded into a fine wire by an extrusion molding machine, sufficiently dried by air drying, and then cut into a predetermined size to obtain a red core having a diameter of 0.5 mm.

[Example 2] Cellulose acetate 27 parts Red lake pigment 20 parts Talc 40 parts Lithium myristate 10 parts Calcium stearate 3 parts Acetone 130 parts Using the above materials, a red core was obtained in the same manner as in Example 1.

Example 2 In Example 1, the amount of lithium myristate used was 1
A red core was obtained in the same manner as in Example 1 except that the amount was changed from 5 parts to 30 parts.

Comparative Example 1 A red core was obtained in the same manner as in Example 1 except that carnauba wax was used instead of lithium myristate.

[Comparative Example 2] A red core was obtained in the same manner as in Example 1 except that lithium myristate was changed to calcium stearate.

Comparative Example 3 A red core was obtained in the same manner as in Example 2 except that carnauba wax was used instead of lithium myristate.

[Comparative Example 4] A red core was obtained in the same manner as in Example 2 except that lithium stearate was used instead of lithium myristate.

[Comparative Example 5] A red core was obtained in the same manner as in Example 3, except that lithium myristate was changed to polyethylene wax.

Comparative Example 6 A red core was obtained in the same manner as in Example 1 except that lithium myristate was not used.

(Effects of the invention) Table 1 shows the measurement results of the bending strength, the friction coefficient, and the thickness of the products obtained in each example. The bending strength and the coefficient of friction were measured according to JIS S 6005. After writing on a high-quality paper with a load of 200 g, the density was sensory-evaluated based on that of Comparative Example 1.

As can be seen from Table 1, according to the present invention, it is possible to obtain a dark colored pencil lead that suppresses the decrease in bending strength and has a smooth writing taste.

Claims (1)

[Claims] 1. A method for producing a non-fired type colored pencil lead, which comprises kneading and extruding a binder, a coloring material, a extender and a lubricant as main materials, and at least the lubricant is used. A method for producing a colored pencil lead, characterized in that lithium myristate is used as a part.