JP3276497B2 - Manufacturing method of mechanical pencil lead - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a high-strength, thick and smooth core for a mechanical pencil.

[0002]

2. Description of the Related Art Conventionally, mechanical pencils have been made of graphite,
It is manufactured by kneading a body material such as carbon black and an organic binder, shaping the mixture into a rod shape, and then heating at a very slow temperature rising rate from room temperature to 500 ° C. However, in such a method, the steps are complicated, and a core having sufficient strength and concentration has not yet been obtained.

In order to obtain a core having sufficient strength and concentration, a method of adding a metal powder (Japanese Patent Publication No. 48-216)
No. 48), a method of adding a metal chloride (Japanese Patent Publication No. Sho 58)
JP-A-80369) and a method of adding a lithium compound (JP-B-63-82799).

[0004]

However, in the case of solid metal powder, the dispersion in the resin is poor, and in the case of metal chloride, some of them are hygroscopic and difficult to handle in operation, and have a high catalytic effect. For this reason, there is a problem in that the addition of a substance having a great effect originally has an adverse effect, for example, the organic binder changes during heating during kneading.

[0005]

Means for Solving the Problems The present inventors have made intensive studies to solve the above-mentioned problems, and as a result, have come to propose the present invention. That is, by using a vinyl polymer having a polar group in a side chain as an organic conjugate, and further adding a chlorinated product of a higher aliphatic hydrocarbon and / or a chlorinated product of a higher fatty acid ester and a metal salt of naphthenic acid, It has been found that it disperses well in the body, and that the organic binder does not change during heating during kneading and acts as a catalyst during the baking process, so that strength is improved and a dense, smooth core can be obtained. It is.

The polymer having a polar group in the side chain used in the present invention includes vinyl acetate polymer, ethylene / vinyl acetate copolymer, acrylate / vinyl acetate copolymer, vinyl chloride polymer, vinyl chloride / acetic acid. A vinyl copolymer, an acrylate / vinyl chloride copolymer, an acrylate polymer and the like are conceivable. The content of these polymers is desirably 10 to 50% by weight.
If the addition amount is 0% by weight or less, the bending strength is not sufficient, and if the addition amount is 50% by weight or more, the writing becomes poor.

Chlorinated higher aliphatic hydrocarbons include:
There are chlorinated products of aliphatic hydrocarbons such as paraffin wax and normal paraffin wax, and chlorinated products of higher fatty acid esters include stearic acid, linoleic acid,
There are chlorinated products of higher aliphatic alkyl esters such as oleic acid and glycerin esters. The chlorine content of these chlorinated products is not limited to a narrow range, and any generally used 20 to 80% by weight can be used. The amount of these chlorine compounds added is
Considering the effect on the bending strength, it is desirable to set the content to 0.1 to 10.0% by weight. If the addition amount is 0.1% by weight or less, the effect on the bending strength does not appear and the addition amount is 10.0% by weight or more. With the amount, the effect on the bending strength becomes constant, and if added more, it becomes meaningless.

[0008] Naphthenate metal salts include zinc naphthenate,
Iron, cobalt, calcium, manganese, nickel, lithium, etc. can be used, but considering the effect on bending strength, zinc and iron compounds are desirable, and they may be used alone or in combination of two or more. You can also.
The addition amount of these naphthenic acid metal salts is desirably 0.1 to 10.0% by weight. When the addition amount is 0.1% by weight or less, the effect on bending strength is not exhibited, and when the addition amount is 10.0% by weight or more. It will be awkward to write.

As the body material, those usually used are used. For example, graphite, carbon black, graphitized carbon black, quiche graphite and the like can be used, but graphite is particularly preferable.

The above-mentioned organic conjugate, extender, chlorinated higher aliphatic hydrocarbon and / or chlorinated higher fatty acid ester, metal salt of naphthenic acid, and three rolls of wax used as a molding aid, etc. After sufficiently mixing with a Henschel mixer, a kneader, etc., the mixture is molded into a rod using an extrusion molding machine, and at least 900 ° C. in a non-oxidizing atmosphere.
Baking. Further, the oil is immersed in lard, spindle oil, liquid paraffin, silicon oil or the like which is usually used.

[0011]

In the present invention, the effect of the combined use of the chlorinated higher aliphatic hydrocarbon and / or the chlorinated higher fatty acid ester and the metal salt of naphthenic acid is such that the metal salt of naphthenic acid is reacted with a solvent or an organic conjugate. It is presumed to be in a homogeneous dispersion state because of compatibility, and the uniformly dispersed metal naphthenate promotes the dehydrochlorination reaction of the chlorinated product, and the hydrogen chloride gas promotes the carbonization of the organic conjugate. However, it is presumed that a large amount of carbide remains as a residue of the organic binder, and the reinforcing material is sufficiently reinforced. In addition, since the metal naphthenate is uniformly dispersed as described above,
It is presumed that the structure of the core subjected to the firing treatment has a uniform structure, and has a rich and smooth writing taste.

[0012]

EXAMPLES Examples and comparative examples of the method for producing a mechanical pencil lead according to the present invention will be shown below, but the present invention is not limited to these examples. In the examples, parts are parts by weight. Example 1 250 parts of polyvinyl acetate 250 parts of wax 50 parts of graphite 550 parts of chlorinated paraffin 50 parts of iron naphthenate 20 parts After kneading these materials well with a kneader and removing the solvent, they were formed into a core by an extrusion molding machine. did. This is 100
After oxidizing at 24 ° C. for 24 hours and at 200 ° C. for 6 hours, it is baked at 1000 ° C. for 1 hour in a nitrogen atmosphere, and the obtained core is placed in liquid paraffin heated to 100 ° C. for 60 hours.
It was immersed for a minute to obtain a finished core. Example 2 Polyvinyl acetate 250 parts Wax 50 parts Graphite 550 parts Chlorinated fatty acid glyceride 40 parts Zinc naphthenate 15 parts A core was obtained in the same manner as in Example 1. Example 3 Polyvinyl chloride 250 parts Wax 50 parts Graphite 550 parts Chlorinated paraffin 50 parts Iron naphthenate 20 parts A core was obtained in the same manner as in Example 1. Example 4 Polyvinyl chloride 250 parts Wax 50 parts Graphite 550 parts Chlorinated paraffin 50 parts Iron naphthenate 10 parts Iron naphthenate 10 parts A core was obtained in the same manner as in Example 1. Comparative Example 1 250 parts of polyvinyl acetate 50 parts of wax 550 parts of graphite A core was obtained in the same manner as in Example 1. Comparative Example 2 Polyvinyl chloride 250 parts Wax 50 parts Graphite 550 parts A core was obtained in the same manner as in Example 1. Comparative Example 3 Polyvinyl acetate 250 parts Wax 50 parts Graphite 550 parts Ferric oxide 5 parts A core was obtained in the same manner as in Example 1. Comparative Example 4 Polyvinyl chloride 250 parts Wax 50 parts Graphite 550 parts Aluminum chloride 0.5 part A core was obtained in the same manner as in Example 1. Table 1 shows the results of flexural strength, concentration, and coefficient of friction of Examples 1 to 4 and Comparative Examples 1 to 4.

[Table 1]

[0013]

As is clear from the above test results, the method for producing a mechanical pencil lead according to the present invention uses a chlorinated higher aliphatic hydrocarbon and / or a chlorinated higher fatty acid ester in combination with a metal salt of naphthenic acid. By addition, the strength is improved, and a dense and smooth core can be obtained.

Claims (1)

(57) [Claims] 1. After kneading with an organic conjugate and a body material as main materials,
In a method for producing a mechanical pencil lead, which is formed into a rod shape and subjected to a baking treatment at a temperature of at least 900 ° C. in a non-oxidizing atmosphere, a vinyl polymer having a polar group in a side chain is used as an organic binder, A method for producing a mechanical pencil lead, comprising adding a chlorinated group hydrocarbon and / or a chlorinated higher fatty acid ester and a metal salt of naphthenic acid in combination.