JP2000026785A - Unbaked colored pencil lead - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an unbaked colored pencil lead having smoothly writing performances, capable of separately producing a colored pencil erasable with a rubber eraser and an unerasable colored pencil by impregnating an unbaked colored pencil lead porous body prepared under specific conditions with a dimethylsilicone oil having a fixed dynamic viscosity. SOLUTION: An unbaked colored pencil lead porous body comprises a water- repellent and oil-repellent substance and/or an extender material or a pigment coated with the water-repellent and oil-repellent substance but no wax in preparation to form open pores caused by the slightly wetting properties of the water- repellent and oil-repellent properties. The porous body is impregnated with a dimethylsilicone oil having 5-3,000 cST dynamic viscosity at 25 deg.C.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wooden pencil core and a pencil pencil for mechanical pencils. The present invention relates to both a conventional non-fired pencil lead which cannot be erased with an eraser and a non-fired pencil lead which can be easily erased with an eraser. To provide.

[0002]

2. Description of the Related Art A conventional non-baked colored pencil lead is prepared by dissolving and swelling an organic polymer substance as a binder with a solvent such as water or a plasticizer as necessary, and then with a wax, a body material, a coloring agent, and the like. It is manufactured by a wet method in which after kneading and extrusion, the solvent or plasticizer is removed by drying.

[0003] However, there is a problem that an enormous drying time is required because the drying temperature must be set to be equal to or lower than the melting point of the wax to prevent bleeding of the wax in the drying step. In addition, among cores manufactured by a dry method in which a drying step is omitted without using a solvent or a plasticizer, those which approach the quality of a wet method core are not commercially available. The conventional wet-type color pencil lead, in terms of strength and writing taste, partially attenuates the adhesion of the base material and colorant by the binder with waxes, so that it wears out at the time of drawing, improving lubricity and coloring. Has been expressed.

[0004] However, when the waxes are kneaded and molded together with a composition such as a constitutional material, a coloring agent, a binder, etc., the effect on smooth brush feeling and excellent coloring properties is great, but the strength is greatly reduced, and the strength is low. A color pencil lead satisfying the balance of writing taste has not been obtained. In addition, non-burning colored pencil cores declaring erasability are also commercially available, but most of them contain a binder and a wax, which are non-polar organic substances, as main components to remove them from paper fibers. By making it easier and softer to enhance coloring and drawing with low pen pressure,
At the time of drawing, it is difficult for the core composition to enter between the fibers of the paper, thereby exhibiting erasability.

However, although the core composition is hardly inserted between the fibers of the paper at the time of drawing, the erasability is exhibited,
However, at the time of drawing, the coloring agent is firmly fixed between the fibers of the paper by the waxes, and the core composition once fixed between the fibers of the paper is completely removed by the adsorption force of the eraser. It cannot be removed and its erasability is not satisfactory in practice. The removal of the drawing line by the attraction force of the eraser can be achieved by using oils and fats or waxes that are liquid at room temperature for all the waxes. However, in the conventional wet method, since heating is performed at 50 to 60 ° C. at the time of drying, fats and oils or waxes bleed and cannot be dried while maintaining the shape of the core, which is not practical.

As a method for solving these problems, the present inventor has proposed a method of coating a water-repellent and oil-repellent substance and / or a body material or a pigment coated with a water-repellent and oil-repellent substance with an uncoated body material, a pigment and a binder. Etc. and, if necessary,
After kneading with a solvent or a plasticizer, etc., after extrusion molding, the solvent, the plasticizer, etc. are dried and removed, so that the water- and oil-repellent substance is hardly wetted to form open pores, which can be worn during drawing. A non-fired colored pencil core porous body, which is completed by impregnating the porous body with oils or waxes or the like, and impregnated with a solid oil or fat or wax at room temperature, so that it cannot be erased with a conventional eraser. It discloses that a colored pencil lead can be obtained, and that a non-baked colored pencil lead that can be easily erased with an eraser can be obtained by impregnating with a liquid oil or wax at room temperature. (Patent No. 2641810, JP-A-5-3314
No. 06, JP-A-7-126568).

However, according to this method, some of the pigments (soluble azo pigments and dye lake dyes) are easily soluble in fats and oils and waxes. There has been a problem in that the center has a different hue and may contaminate the impregnation bath with oils and fats.

[0008]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned drawbacks of the conventional method of producing a non-fired colored pencil lead, and to provide extremely excellent mechanical strength such as bending strength and tip strength, and smoothness. An object of the present invention is to provide a non-fired color pencil lead having a good writing taste and no color unevenness. Further, an oil of a specific viscosity, which does not dissolve even with a specific pigment (such as a soluble azo pigment), is selected. A conventional non-fired color pencil lead which cannot be erased with an eraser, and a non-fired color pencil core which can be easily erased with an eraser.
It is to make it possible to make seeds.

[0009]

Means for Solving the Problems The present inventor has made intensive studies to solve the above-mentioned problems, and as a result, has found that water- and oil-repellent substances and / or
Or a body material or pigment coated with a water / oil repellent substance,
After kneading, extruding, and molding the compounded composition together with a solvent, the solvent and the like are dried and removed to form open pores due to the water-repellent and oil-repellent substance being hardly wetted. The present invention has been found to be able to solve the problem by impregnating with dimethyl silicone oil.

That is, the non-fired colored pencil lead of the present invention comprises a water- and oil-repellent substance and / or a body or pigment coated with a water- and oil-repellent substance, and an uncoated body material, a pigment, a binder and the like. After kneading and extruding with a material, and a solvent or a plasticizer as necessary, the solvent, the plasticizer, etc. are dried and removed to form open pores caused by the water- and oil-repellent substance being hardly wetted. When drawing, a wearable non-fired color pencil core porous body is formed, and the porous body is impregnated with dimethyl silicone oil having a kinematic viscosity at 25 ° C. of 5 to 3,000 cSt.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The contents of the present invention will be described below in detail. Any dimethyl silicone oil impregnated in the core of the present invention can be used as long as the kinematic viscosity at 25 ° C is in the range of 5 to 3,000 cSt. If it is less than 5 cSt, the volatility is high, the stability with time is extremely low, and if long-term stability is required, 20 cSt or more is preferable. On the other hand, if it exceeds 3,000 cSt, it depends on the pore diameter of the core, but it becomes difficult to uniformly impregnate the silicone oil up to the center of the core. Naturally, these several types of silicone oils can be mixed and used.
The kinematic viscosity at 25 ° C. is 5 to 100 c.
In the case of selecting from a dimethyl silicone oil of St and using a wax type color core that cannot be erased by a conventional eraser, that is, in the case where the core is required to have fixability, a dimethyl silicone oil having a kinematic viscosity at 25 ° C of 200 to 3,000 cSt. And more preferably dimethyl silicone oil having a kinematic viscosity at 25 ° C of 500 to 3,000 cSt.

[0012] As a method of impregnating with dimethyl silicone oil, a non-fired colored pencil lead porous body is immersed in the oil, and heated if necessary to fill the pores. In addition, for the purpose of promoting impregnation, decompression and pressurization can also be performed.
Of course it is possible.

The water-repellent and oil-repellent substances used in the present invention may be blended as they are in powder form, or may be blended with a substance coated with another body material and / or a pigment, according to their properties.
An appropriate method of use may be selected.

As the water-repellent and oil-repellent substance used as a powder, any of fluorinated graphite, carbon fluoride, fluororesin powder such as PTFE (polytetrafluoroethylene), boron nitride and the like can be used alone or in combination. In order to form a porous body having a large strength, an appropriate amount of wear, and a large amount of impregnated oil, it is preferable to use (CF) _n- type fluorinated graphite because it has the smallest surface energy and is excellent in lubricity. . Considering the production of light-colored pencils, it is preferable to use boron nitride having high whiteness and excellent lubricity. Their blending amounts are not determined unconditionally by the surface energy of the water- and oil-repellent substance, but in consideration of the hardness of the core coming from the impregnation ratio of dimethyl silicone oil, brushability and mechanical strength, 2 to 2 of the total blending composition amount Addition and blending of 20% by weight is preferred.

When the binder used is water-soluble and water is used as the solvent, N-long-chain acyl-basic amino acids such as N-lauroyl-L-lysine, which are powdery water-repellent substances, and / or N- -Lauroyl aspartic acid β lauryl ester, N-stearyl aspartic acid β stearyl-
Higher fatty acid esters of N-long-chain acyl acidic amino acids such as esters can also be used. In this case, the blending amount of the higher fatty acid ester of the N-long-chain acyl basic amino acid and the N-long-chain acyl acidic amino acid is 3 to 3 times the total blending composition amount.
40% by weight is preferred. Of course, the above-mentioned water- and oil-repellent substances can be mixed and used at the same time.

Examples of the pigment used in the present invention include organic pigments having low oil resistance such as disazo yellow AAA and pyrazolone orange, other known organic pigments such as phthalocyanine blue, phthalocyanine green, and quinacridone red, and carbon black. Known inorganic pigments such as iron black, red iron oxide, navy blue and titanium dioxide can all be used. As the dye pigment, a final color or the like can be used, but care must be taken because only a part of the dye is eluted in dimethyl silicone oil.

The binder used in the present invention includes calcium carbonate, kaolin, talc, precipitated barium sulfate,
All known body materials such as talc, mica, and potassium titanate whiskers can be used. As the binder used in the present invention, carboxymethylcellulose, methylcellulose, ethylcellulose, hydroxyethylcellulose, hydroxypropylcellulose, cellulose acetate, cellulose derivatives such as cellulose nitrate, pullulan,
Polyvinyl alcohol, polyvinyl butyral, polymethyl methacrylate, tragacanth gum, gum arabic, guar gum, dammar gum, locust bean gum, etc. can be used alone or in combination regardless of nature, but in consideration of drying time, water-soluble resin Or, in a thermoplastic resin that dissolves and swells in a low-boiling solvent, the bending strength is large in consideration of writing taste and strength,
It is preferable to select a rigid one.

The non-fired colored pencil lead of the present invention thus constituted has the following effects. A substance excellent in water repellency and oil repellency has a large contact angle with an organic polymer substance as a binder, a solvent such as water, a plasticizer, and the like, and is hardly wet.
Therefore kneading with other compounding composition, and solvent, etc.,
Extrusion molding, the molded product further dried and removed the solvent, etc.,
Gaps (open pores) due to the poor wetting of water- and oil-repellent substances
To obtain a non-fired colored pencil lead porous body. The open pores can be impregnated with oil or the like. When impregnating this non-baked colored pencil core with dimethyl silicone oil,
The pigment is not eluted during the impregnation, the hue at the tip and the center of the core is uniform and non-uniform, and the pigment does not contaminate the oil impregnation bath. Further, by changing the viscosity of the dimethyl silicone oil, various kinds of colored pencil cores having different coloring properties, slipperiness, erasability, strength, hardness, etc. can be obtained from one kind of non-baked colored pencil core porous body. That is, 25 ° C
Impregnated with a dimethyl silicone oil having a kinematic viscosity of 200 to 3,000 cSt, a conventional unfired colored pencil lead that cannot be erased with an eraser is obtained.
By impregnating with dimethyl silicone oil having a kinematic viscosity at 5 ° C. of 5 to 100 cSt, a non-fired colored pencil lead that can be easily erased with an eraser is obtained.

[0019]

EXAMPLES The present invention will be described more specifically with reference to the following examples, but the present invention is not limited to these examples.

Example 1 Carboxymethyl cellulose 6% by weight Talc 71% by weight Titanium dioxide 10% by weight Disazo yellow AAA 4% by weight Phthalocyanine blue 4% by weight Fluorinated graphite 5% by weight Water equivalent to the above composition by weight After mixing and dispersing them in a kneader, kneading them with two rolls to adjust the water content, pelletizing the resulting mixture, extruding it with a single screw type extruder, and drying at 120 ° C. for 3 hours. Then, water was removed to obtain a non-fired green pencil lead porous body having a diameter of 3.0 mm. Dimethyl silicone oil (Kinematic viscosity at 25 ° C .: 30 cSt) at 120 ° C.
To obtain a non-fired green pencil lead having a diameter of 3.0 mm.
Table 1 shows the results.

Example 2 The same non-fired green pencil lead porous material as in Example 1 was impregnated with dimethyl silicone oil (kinematic viscosity at 25 ° C .: 1,000 cSt) at 120 ° C. to obtain a non-fired green pencil having a diameter of 3.0 mm. A green pencil lead was obtained. Table 1 shows the results.

Comparative Example 1 A non-fired green pencil lead having a diameter of 3.0 mm was obtained by impregnating liquid paraffin at 120 ° C. in the same porous non-fired green pencil lead as in Example 1. Table 1 shows the results.

(Comparative Example 2) Stearic acid 20% by weight Microcrystalline wax 15% by weight Synthetic wax 65% by weight The same non-fired green pencil lead as in Example 1 was melted at 120 ° C. with a melt containing the above composition. It was impregnated to obtain a non-fired green pencil lead having a diameter of 3.0 mm. Table 1 shows the results.

Comparative Example 3 Carboxymethylcellulose 7% by weight Talc 55% by weight Titanium dioxide 10% by weight Disazo Yellow AAA 4% by weight Phthalocyanine blue 4% by weight Stearic acid 4% by weight Microcrystalline wax 3% by weight Synthetic wood wax 13% by weight After adding water corresponding to the same weight to the above blended composition, mixing and dispersing them in a kneader, adjusting the water content while kneading with two rolls, pelletizing the kneaded product and using a single screw extruder. After extrusion molding, drying was performed at 50 ° C. for 60 hours to remove water, and a non-fired green pencil lead having a diameter of 3.0 mm was obtained. Table 1 shows the results.

With respect to the non-fired colored pencil cores of Examples 1 and 2 and Comparative Examples 1 to 3, the eraser erasing rate, contamination of the impregnation bath, and color unevenness of the cores were measured and confirmed. (1) Eraser Erasure Rate The eraser erasure rate was determined from the following equation. Eraser erasure rate (%) = [{(drawing line density)-(density after drawing line deletion)} / (drawing line density)] x 100 (2) Contamination of impregnation bath The impregnation bath after impregnation of the non-fired colored pencil lead dissolves the pigment. Was visually checked for contamination. (3) Color unevenness of the core The difference between the hue at the tip of the core and the hue at the center was confirmed. Further, the core was divided vertically and the hues at the outer peripheral portion and the central portion were visually confirmed.

[0026]

[Table 1]

Examples 1 and 2 and Comparative Examples 1 to 3 shown in Table 1
The test results show that the non-baked colored pencil lead of the embodiment of the present invention uses a dimethyl silicone oil having a specific viscosity to separate a color lead from which the eraser can be erased from the same core and a conventional color lead which cannot be erased. In addition, it shows that the core has no color unevenness even when the entire core is viewed. In contrast,
In Comparative Examples 1 and 2, erasable color cores and non-erasable color cores could be separately formed, but the impregnation bath was contaminated and color unevenness occurred. Specifically, Disazo Yellow AAA, which has slightly lower oil resistance, eluted in the impregnation bath, and the bath was colored yellow. The core is disazo yellow AAA at the tip and outer periphery.
Eluted, the bluish color was stronger than in the center, and color unevenness was formed. Comparative Example 3 is one of the examples of blending a color core that cannot be erased with a conventional eraser.

[0028]

The present invention is as described above. By adding a water-repellent and oil-repellent substance, a non-fired color pencil core porous body which is large in strength and can be worn at the time of drawing is produced, and a specific porous body is prepared. Impregnated with dimethyl silicone oil of high viscosity, this is a high quality non-fired color pencil lead with little variation.Easily erased with conventional non-fired color pencil lead and eraser that cannot be erased with eraser by selecting dimethyl silicone oil with different viscosity Any of the non-fired colored pencil cores that can be obtained can be obtained.

Claims (1)

[Claims] In the step of producing a non-fired colored pencil lead, a wax is not added and blended at the time of blending, and a water / oil repellent substance and / or a filler or a pigment coated with a water / oil repellent substance are added and blended. Thereby, after the water- and oil-repellent substance is hardly wetted to form open pores to form a non-fired color pencil core porous body, the kinematic viscosity at 25 ° C. of the porous body is 5 to 3,000 cSt. A non-fired colored pencil lead impregnated with dimethyl silicone oil in the range described above.