KR100860499B1 - Pencil Lead Composition and Pencil Lead Manufacturing Thereby - Google Patents

Abstract

In order to improve processability and satisfy bending strength and concentration together, graphite, an organic binder, is used as a main material, kneaded by adding a solvent or a plasticizer, and extruded into fine wires, followed by calcining. A pencil lead is prepared by fixing an oil-impregnated sintered body, the graphite as a sieving agent and a thermoplastic resin as an organic binder, and a pencil lead composition comprising tin maleate polymer and calcium stearate.

Tin-based maleate and calcium stearate are each added in an amount of 0.1 to 15% by weight, and thermoplastic resin is added to 35 to 60% by weight.

Pencil lead, graphite, calcining, sieving agent, organic binder, chlorinated resin, tin maleate polymer, calcium stearate

Description

Pencil lead composition and pencil lead manufactured using the same {Pencil Lead Composition and Pencil Lead Manufacturing Thereby}

The present invention relates to a pencil lead composition and a pencil lead prepared using the same, more specifically, it contains a tin-based maleate polymer and calcium stearate, thereby improving the workability in the work process and simultaneously satisfy the bending strength and concentration and It relates to a pencil lead manufactured using this.

In general, the pencil lead is composed of the sieving graphite and the organic binder as a main component, kneaded by adding a solvent or a plasticizer to the main component of the above, prepared by extrusion molding into a fine wire, and then sintered by a plastic treatment to be impregnated in oil. do.

Plastic pencil lead manufacturing method made as described above is largely divided into clay type and carbon type.

The clay type is a method of using a clay as a binder and an inorganic material such as boron nitride, talc, mica, carbon bolac, and water as a surfactant and a plasticizer, and calcining at a high temperature. It is mainly used for wood pencil in terms of practical strength and price.                         

In the carbon type plastic pencil manufacturing method, the resin or the pitch is used as the binder and the inorganic sieve, and the lubricant is used, and the resin or the pitch is carbonized by firing in a non-oxidizing atmosphere at 800 to 1400 ° C. As a method of obtaining a sintered compact by sintering, the pencil lead for mechanical pencils is an example.

Plastic pencil lead manufacturing method made as described above should be subjected to a calcination process to increase the temperature gradually from room temperature to 500 ℃ in order to ensure that the pencil core has a certain strength or more. This firing process is very difficult and wastes a lot of time.

Therefore, in recent years, various methods have been attempted to improve the strength of the pencil lead in addition to the above-described method.

 For example, a method of strengthening the bonding of a composition by mixing carbonaceous metal carbides or oxides in the material with a weight of about 30% by weight in a binder which is carbonized by heating and firing, and diluting and dissolving metal chlorides in a solvent. There is a method of adding to a settlement, a method of adding a metal chloride to a pencil lead obtained by mixing, kneading, mixing, kneading, mixing, and coloring a plasticizer such as graphite and carbon black, and thermoplastic resin as a binder.

Plastic pencil core manufacturing method using a thermoplastic resin as an organic binder in order to improve the strength as described above, there is a limit in obtaining a high strength, high concentration pencil core because the thermoplastic resin is changed by heating during the dispersion and kneading process.                         

Moreover, the addition of metal chlorides, metal carbides, and the like to promote carbonization did not yield satisfactory pencil lead.

In order to solve this problem, the inventors of the present invention have repeatedly tested the preparation of pencil lead with various materials and methods, and in the case of containing tin maleate polymer and calcium stearate, It was confirmed that the improvement and stabilization to satisfy the strength and concentration at the same time and came to invent the pencil core composition of the present invention.

The pencil lead composition proposed by the present invention includes graphite as a sieving material, thermoplastic resin as an organic binder, tin maleate polymer, and calcium stearate.

Moreover, the pencil lead composition which this invention proposes further adds a solvent and a plasticizer.

The pencil lead proposed by the present invention uses organic binders such as graphite, polyvinyl chloride, polyvinylidene chloride, polyethylene, tin-based maleate polymer and calcium stearate as main materials, and a solvent or a plasticizer is added thereto. The mixture is kneaded and then extruded into fine wires and calcined to produce a sintered body which is impregnated with an oily substance (oil or fat).

The tin maleate polymer and calcium stearate are added in a range of about 0.1 to 15% by weight based on 100% by weight.

The thermoplastic resin as the organic binder is made of chlorine-containing resin. As said chlorine-containing resin, polyvinyl chloride is suitable.                     

In addition to the polyvinyl chloride, the thermoplastic resin as the organic binder is polyvinylidene chloride, polyethylene, polystyrene, AS resin (acrylonitrile styrene resin), ABS resin (acrylonitrile butadiene styrene resin), nitrocellulose, acetyl cellulose, It is also possible to use one or more selected from phenol resin, polyvinyl alcohol, etc., or to mix.

The organic binder is selected and added in the range of about 35 to 60% by weight based on 100% by weight of the total.

The graphite is a sieving material that is essentially used to maintain the strength of the pencil lead, it is preferable that the graphite is included in the range of about 10 to 90% by weight in the whole sieving material.

The above-mentioned graphite can be arbitrarily selected from natural graphite, artificial graphite, flake graphite (graphite having a thin layer thickness of graphite crystal), or the like, which is generally used for calcined pencil cores.

The graphite may be used together with talc and mica, which are inorganic sieves, and in addition to the talc and mica, boron nitride and the like may be used as a sieve.

It is preferable to use said talc for which the surface was treated with the silane coupling agent, and flaky talc by the wet grinding method.

The mica may be used by using natural mica or by combining one or more kinds of synthetic mica.

In addition to the above organic binders and sieving agents, fillers selected from inorganic fine powders such as carbon black and amorphous silica, and pore-forming materials such as depolymerized resin powders and sublimable substances, solvents, and the like may be appropriately added as necessary. It is also possible.

As the oily material impregnated after the firing treatment, at least one selected from fluid paraffin, spindle oil, microcrystalline wax, low molecular polyethylene wax, paraffin wax, squaran and the like is used alone or in combination of two or more kinds.

Next, the Example of the pencil lead composition which concerns on this invention is described.

Example 1

First, 35% by weight of polyvinyl chloride as an organic binder, 45% by weight of graphite as a sieving material, 19% by weight of dioctylphthalate, 2% by weight of tin-based maleate polymer, and 2% by weight of calcium stearate are mixed. Was prepared.

The blended composition is kneaded in a hexyl mixer, then kneaded again in three rolls or the like, extruded in a thin wire using an extruder, heated to 280 ° C in air, and then heated to 1000 ° C in a non-oxidizing atmosphere. It carried out and impregnated with the spindle oil which is an oily thing, and produced the shim for mechanical pencils with a diameter of 0.5 mm.

[Example 2 to Example 4]

In Example 1 described above, except that the tin-based maleate polymer was fixed at 2% by weight, and calcium stearate was changed from 2% by weight to 4%, 8%, and 15% by weight, respectively. It manufactured by the same method as 1, and obtained the shim for mechanical pencils of diameter 0.5mm, respectively.

[Example 5 to Example 7]                     

In Example 1 described above, except that calcium stearate was fixed at 2% by weight, and the tin-based maleate polymer was changed from 2% by weight to 4%, 8%, and 15% by weight, respectively. Manufactured in the same manner as 1, a shim for a mechanical pencil having a diameter of 0.5 mm was obtained.

[Comparative Example 1 to Comparative Example 4]

In Example 1 described above, except that 2% by weight of zinc stearate, 4% by weight, 8% by weight, 15% by weight instead of 2% by weight of calcium stearate was prepared in the same manner as in Example 1 A shim for mechanical pencils having a diameter of 0.5 mm was obtained.

Comparative Example 5

In Example 1 described above, except that the tin-based maleate polymer was not used, the same procedure was followed as in Example 1 to obtain a shim for a pencil having a diameter of 0.5 mm.

Comparative Example 6

In Example 1 described above, except that calcium stearate was not used, the same procedure was followed as in Example 1 to obtain a shim for a mechanical pencil having a diameter of 0.5 mm.

The bending strength and the concentration of the mechanical pencil shims of Examples 1 to 8 and Comparative Examples 1 to 6 prepared as described above were measured, and the results are shown in Table 1 below.

NO Bending strength (g / ㎡) Concentration (D) Example One 36,500 0.29 2 34,700 0.31 3 32,000 0.31 4 27,500 0.33 5 35,700 0.30 6 34,000 0.31 7 30,000 0.32 Comparative example One 33,000 0.29 2 31,600 0.30 3 30,500 0.30 4 25,000 0.34 5 28,900 0.28 6 29,000 0.30

It can be seen from Table 1 that the bending strength decreases and the concentration increases as the amount of calcium stearate is increased while the amount of tin-based maleate polymer is fixed (Examples 1 to 4).

In addition, it can be seen that the bending strength decreases and the concentration increases as the amount of tin-based maleate polymer is increased while the amount of calcium stearate is fixed (Examples 1 and 5 to 7).

Compared with Examples 1 to 4 described above, the present invention using calcium stearate is more excellent in the case of the same amount of addition as compared with the use of zinc stearate It can be confirmed that the strength is shown.

In Comparative Example 5 and Comparative Example 6, when the calcium stearate and tin maleate polymer are not used, the bending strength is very low.

Therefore, when calcium stearate and tin maleate polymer are generally added at the same time, an appropriate concentration can be maintained during the kneading process, and the bending strength of the calcined pencil lead is excellent. And it can be seen that the addition amount of calcium stearate and tin-based maleic acid salt polymer is better in bending strength than when the addition amount is increased.

In the above, a preferred embodiment of the pencil core composition according to the present invention has been described, but the present invention is not limited thereto, and various modifications can be made within the scope of the claims, the detailed description of the invention, and the accompanying drawings. It also falls within the scope of the present invention.

According to the pencil lead composition according to the present invention made as described above, dispersing and kneading by using a chlorine-containing resin as an organic binder and using a tin maleate polymer and calcium stearate in the range of 0.1 to 15% by weight, respectively It is possible to obtain a pencil lead that improves the workability in the work process such as the above and satisfies the bending strength and the concentration together.

Claims (5)

Graphite, which is a matrix material, Thermoplastic resin as an organic binder, Tin maleate polymer, Pencil lead composition containing calcium stearate. The method of claim 1, The tin-based maleate polymer and calcium stearate are selected from the range of 0.1 to 15% by weight relative to the total 100% by weight pencil core composition. The method of claim 1, The thermoplastic binder, which is the organic binder, is polyvinyl chloride, polyvinylidene chloride, polyethylene, polystyrene, AS resin (acrylonitrile styrene resin), ABS resin (acrylonitrile butadiene styrene resin), nitrocellulose, acetyl cellulose, phenol resin Select one or more among polyvinyl alcohol and use alone or in combination, The amount of the organic binder added is selected from the range of 35 to 60% by weight based on 100% by weight of the total pencil core composition. A pencil core composition is prepared by mixing and adding a graphite sieve, a thermoplastic resin, an organic binder, a tin maleate polymer, calcium stearate, a solvent or a plasticizer. A pencil core manufactured by impregnating an oily substance with a sintered body obtained by kneading this pencil core composition, followed by extrusion molding in a thin wire shape and firing. The method of claim 4, wherein As the oily substance, pencil lead is used alone or in combination of two or more by selecting one or more selected from liquid paraffin, spindle oil, microcrystalline wax, low molecular polyethylene wax, paraffin wax, and squaran.