JP3161043B2 - Pencil lead - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a pencil lead comprising a fired core and an oil impregnated in pores of the fired core, wherein paraffin wax is used as at least a part of the oil. About things.

[0002]

2. Description of the Related Art A pencil lead composed of a fired core and an oil impregnated in pores of the fired core uses clay, various synthetic resins, and the like as a binder, and is used for building materials such as graphite and other materials. After uniformly dispersing with a coloring kneader, a Henschel mixer, three rolls, etc. together with a coloring material, a pore-forming material, a plasticizer, a solvent, etc., which are used accordingly, heat-treating at a high temperature to form a porous body It is manufactured by obtaining a core and impregnating it with an oil. Here, as the oily substance, spindle oil, silicon-
Various oils, liquid paraffins, microcrystalline waxes, montan waxes, bohemia waxes, carnauba waxes and the like, including various combinations thereof, are known. Paraffin wax is one of them.

[0003] Further, the applicant has previously improved the inverse correlation between the density of handwriting and the fixability to a writing surface, and the density has been increased.
In order to obtain a handwriting with good fixability to a writing surface, it has been proposed to use a solid oily substance at normal temperature as an oily substance, and to write the oil in a softened state by heating the oily substance (Japanese Unexamined Patent Publication (Kokai) No. Heisei 3). -284996).

[0004]

SUMMARY OF THE INVENTION The present invention is one of the continuations of the above-mentioned proposal, and a pencil suitable for contributing to an improvement in the inverse correlation between the density of handwriting by heating writing and the fixability to a writing surface. The purpose is to provide a wick.

[0005]

A particular paraffin wax, specifically, a paraffin wax having an average carbon number distribution of 30 or more and a standard deviation of 3.5 or less is used as an oil. That is, the present invention relates to a pencil lead comprising a calcined core and an oil impregnated in pores of the calcined core, wherein paraffin wax is used as at least a part of the oil. The gist of the present invention is a pencil lead, wherein a wax having an average value of carbon number distribution of 30 or more and a standard deviation of 3.5 or less is used as the wax.

The details will be described below. Paraffin wax
It is a mixture of saturated hydrocarbons having a molecular weight of about 300 to 500 and containing a linear hydrocarbon as a main component, and the linear hydrocarbon has a distribution of carbon number. That is, it has a standard deviation together with the average value of the carbon number. Incidentally, general commercial products have an average carbon number of about 20 to 35 and a standard deviation of about 2.3 to 4.2.

[0007] The larger the average value of the carbon number, the harder the solidified state. Paraffin wax is expected to work as an adhesive between the powder forming the handwriting and the writing surface, and in this regard, the harder the solidified state, the better. However, as a general rule in the distribution, the standard deviation increases as the average value increases. If the standard deviation is large, the criticality of the viscosity change near the melting point also becomes low. That is, solidification becomes slow. When the solidification becomes slower, for example, the portion that is between the handwriting powder and the writing surface and does not work as an adhesive increases, for example, when absorbed by the writing surface.

Therefore, in order to work as an adhesive,
It is desired that not only the average value be large but also the standard deviation be small. From such a point of view, the present inventor has studied and, in actual fact, has selected the case where the average value used in the present invention is 30 or more and the standard deviation is 3.5 or less.

[0009] The fired core may be of various types as described above. For example, polyvinyl chloride, polyvinylidene chloride, chlorinated polyethylene, urea resin, melanin resin, furan resin, polyvinyl alcohol, polyacrylamide, butyl rubber and the like as a binder, obtained by carbonization, And those obtained by sintering using clay as a binder. Body materials such as graphite and boron nitride and other materials may be appropriately selected. If the porosity is also about 10 to 60%, the oil can be sufficiently impregnated, and the strength of the core itself is sufficient to make the core for a sharp pencil relatively thin.
Of course, even if the porosity is outside this range, it will be improved accordingly. It can also be used in combination with a liquid oil at room temperature, and can be used for writing at room temperature.

[0010]

【Example】

<Example 1> 30 parts by weight of polyvinyl chloride 50 parts by weight of graphite 5 parts by weight of carbon black 2 parts by weight of stearic acid 15 parts by weight of dioctyl phthalate After thoroughly kneading the above-mentioned blended materials with three rolls, a thin line was formed. Extrusion molding, heat treatment to 300 ° C in air, heat treatment to 1000 ° C in an inert atmosphere, and a shear of nominal diameter 0.5
A fired core body for a pupil pencil was obtained. Then, HNP-11 (paraffin wax manufactured by Nippon Seiro Co., Ltd .: average value of carbon number distribution: 31.9, standard deviation: 1.8) was added to the fired core body.
Was heated and melted at 120 ° C. for impregnation.

<Examples 2 and 3> In Example 1, HN
Instead of P-11, HNP-1 (paraffin wax manufactured by Nippon Seiro Co., Ltd .: average value of carbon number distribution 30.6, standard deviation 2.2), HNP-9 (manufactured by Nippon Seiro Co., Ltd.) Paraffin wax: The same procedure as in Example 1 was carried out except that the average value of the carbon number distribution was 36.3 and the standard deviation was 3.1).

<Embodiment 4> In Embodiment 1, the HNP-
In the same manner as in Example 1, except that HNP-11 was added with 10% by weight of liquid paraffin instead of HNP-11.

<Comparative Examples 1-3> In Example 1, HN
In place of P-11, a paraffin wax standard product manufactured by Nippon Seiro Co., Ltd., a variety 155 (average carbon number distribution of 34.4,
Standard deviation 4.18), variety 135 (average carbon number distribution 27.7, standard deviation 2.87), variety 115 (average carbon number distribution 24.0, standard deviation 2.32) , All in the same manner as in Example 1.

Comparative Example 4 In Example 4, HNP-
Example 4 was carried out in the same manner as in Example 4 except that paraffin wax standard var. 155 (described above) manufactured by Nippon Seiro Co., Ltd. was used instead of 11.

The sample obtained in each example is housed in a pencil lead holder having a sharp pencil structure of a plotter. Table 1 shows the results of writing on a high-quality paper (Kimoto Co., Ltd .: KGP) under a load of 400 g and measuring the density and fixability of the handwriting. The fixing property is defined as {fixing property} = (100), where α is the reflectance of the writing weight part by a plotter, and β is the reflectance of the writing part by rubbing the writing weight part under constant conditions.
−β) ÷ (100−α) × 100. The smaller the value, the better the fixability.

[0016]

[Table 1]

Table 2 shows the results of the measurement of the density and the fixing property of Example 4 and Comparative Example 4 by setting the temperature of the heating unit to 25 ° C. in the same manner.

[0018]

[Table 2]

[0019]

As can be seen from Table 1, when the pencil lead of the present invention is used, the improvement of the inverse correlation between the density of the handwriting and the fixing property to the writing surface by heating and writing becomes remarkable.

Claims (1)

(57) [Claims] 1. A pencil lead comprising a calcined core and an oil impregnated in pores of the calcined core, wherein paraffin wax is used as at least a part of the oily substance. A pencil lead having an average carbon number distribution of 30 or more and a standard deviation of 3.5 or less.