JP2010077329A - Pencil lead - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pencil lead a having dense handwriting and high fixing properties (when it is abraded or pressed). <P>SOLUTION: A pencil lead having dense handwriting and scarcely staining (when it is abraded and pressed) can be obtained by using oil-soluble smectite, which is swelling layer silicate, at least in a part of impregnating ingredient of baked core material. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a pencil lead in which a large number of pores obtained by firing are impregnated with an impregnation component.

The pencil core uses clay, various synthetic resins, etc. as a binder, and it is uniform with a kneader, Henschel mixer, three rolls, etc. together with a constitution material and coloring agents, pore forming agents, plasticizers, solvents, etc. It is obtained by dispersing and extruding, followed by high-temperature firing at 800 ° C. to 1200 ° C., and impregnating the obtained fired core with various impregnation components depending on the purpose. The impregnation is performed by immersing the fired core in an impregnated material that has been pressurized, decompressed, or heated, and then removing excess impregnated material from the surface. When the core obtained in this way is written, due to the shearing force applied in the direction of movement and the writing pressure applied in the direction perpendicular to the paper surface, the graphite or resin carbide as the core body component collapses and rests on the paper surface with an impregnation component (that is, Adhesion) As the amount of adhesion, that is, the amount of wear powder increases, the paper surface is concealed, so the core handwriting that tends to collapse is darker, but at the same time, the abrasion powder adheres to the hand by rubbing or pressing, or spreads on the paper. Dirt becomes more noticeable. This is considered to be caused by the fact that the writing wear powder adhering to the paper surface is not fixed (that is, fixed) on the paper surface, or that the overlapping wear powder easily peels off.
Conventional techniques for improving the fixability of writing wear powder include those impregnated with fats and oils containing extreme pressure additives (see Patent Document 1) and those impregnated with viscous liquid (see Patent Document 2). .

JP 2001-207103 A JP 2005-213391 A

At the time of writing, the graphite in the wear powder tends to adhere with the cleaved surface, which is a short axis, oriented parallel to the paper surface. As in the invention described in Patent Document 1, in the case where a film is formed on the wear powder using the polar group of the additive, the hydrophobic graphite cleaved surface having no reactive group cannot be covered. It cannot be obtained sufficiently, and therefore the effect of reducing the stain that the writing wear powder spreads on the paper surface due to rubbing is not sufficient. Further, when writing in an environment where papers such as notebooks overlap, the phenomenon that the abrasion powder moves to the paper surface that is covered, that is, transfer cannot be prevented. This is because the cleaved surface of the graphite is not covered, and the polar group of the additive is bonded to the surface hydroxyl group of the covered paper and moves to the covered paper side. At this time, the wear powder also moves with the additive. It can be considered that it ends.
In the technology for improving the fixability, the present applicant has conducted intensive research and created a technology for impregnating a viscous liquid as disclosed in Patent Document 2. However, although this technique can reduce the stain when the handwriting is rubbed by hand, the transfer is fixed on the paper side covered with the viscous liquid and moved to the paper side covered with the various wear powders. was there.

  The gist of the present invention is a pencil lead in which pores obtained by firing are impregnated with an impregnation component, wherein the impregnation component is made of at least an oil-soluble smectite which is a swellable layered silicate.

The oil-soluble smectite dispersed in the impregnated component is lipophilic between the layers, so the impregnated component that is the solvent enters and swells between the layers, and when rubbed by hand or when paper overlaps During pressurization, the solvent oozes from the interlayer. The exuded solvent enters the fine gap between the paper surface and the wear powder and between the wear powder and the wear powder to exert the interfacial tension, so the amount of wear powder that moves is suppressed, and the stain spreading on the paper surface is reduced even in dark handwriting. Inferred.
Further, since the oil-soluble smectite is plate-like, it is covered with the graphite cleaved surface by pressing together with the flat plate surface, so that part or all of the wear powder is covered. Here, the oil-soluble smectite surface has a large negative charge among the swellable layered silicate, and when the negatively charged paper surface is covered, it is fixed on the covered paper surface by electrostatic interaction. Therefore, it is presumed that the movement of the wear powder to the covered paper surface side is also suppressed.
Here, when the exchangeable cation is replaced with an organic cation obtained from a cationic surfactant, the lipophilicity is improved due to the surface active effect, and the impregnating component as a solvent easily penetrates between layers. Since it becomes easy to stay, it becomes possible to hold | maintain many impregnation components between layers, and it is estimated that the effect is acquired more.

Hereinafter, the present invention will be described in detail.
The oil-soluble smectite is obtained by organically modifying ordinary water-soluble smectite by various methods. The method for organic modification is not particularly limited, and any method may be used. For example, after water-soluble smectite is dispersed in water, organic salts such as imidazolium salt and phosphonium salt are mixed and exist between crystal layers. For example, by substituting the cation to be substituted.
The water-soluble smectite used as a precursor is a plate-like crystalline clay mineral, a kind of swellable layered silicate containing various exchangeable cations between layers. It shows a natural property. Further, the surface charge amount called permanent charge is higher than that of other layered silicates. The composition can be classified into several types, for example, natural or synthetic hectorite, saponite, stevensite, beidellite, montmorillonite, nontronite and the like. The unit structure is composed of two tetrahedral sheets formed by connecting Si-O tetrahedral coordination bodies, which are a unit of silicic acid and oxygen, and an octahedral sheet sandwiched between them. It is divided into 2 octahedron type and 3 octahedron type from the difference of ion. This cation functions as an exchangeable cation. In the 2-octahedron type, most of the cations are trivalent cations such as Al and Fe, and montmorillonite, beidellite and nontronite are applicable. The trioctahedral type is mainly composed of divalent cations such as Mg, and includes hectorite, saponite, and stevensite. Examples of commercially available products preferably used in oil-soluble smectites include smectite SAN, SAN316, STN, SEN, SPN (manufactured by Coop Chemical Co., Ltd.), Esben, Esben C, Esben E, Esven W, Esben WX, Organite, Organganite D, Organite T, Esven N400, Esben NX, Esben NX80, Esben NZ, Esben NZ70, Esben NE, Esben NEZ, Esben NO125, Esben NO12 (manufactured by Hojun Co., Ltd.), and the like.

The organic cation obtained from the cationic surfactant is a nonmetallic element ion having an alkyl group in the main chain and / or side chain obtained when the cationic surfactant is ionized in water. Amine ions obtained from alkylamine salts and ester-bonded amine salts, alkylammonium salts, ester-bonded ammonium salts, quaternary ammonium ions obtained from ether-bonded ammonium salts, alkylpyridinium salts, amide-bonded pyridinium salts, and ester-bonded pyridinium salts And pyridinium ions obtained from the above. Among these, quaternary ammonium ions are more preferable because they are ions having the most organic side chains and can exhibit high lipophilicity.
Specific examples of the quaternary ammonium salt include polyoxypropylene / trialkylammonium chloride, polyoxypropylene / trialkylammonium bromide, di (polyoxypropylene) / dialkylammonium chloride, di (polyoxypropylene) / dialkylammonium bromide. , Tri (polyoxypropylene) .alkylammonium chloride, tri (polyoxypropylene) .alkylammonium bromide, and the like.
Further, when the oil-soluble smectite is an oil-soluble hectorite having a structure in which a part of Mg, which is a divalent exchangeable cation, is substituted with a monovalent cation, Li, It is more preferable because a large amount of the impregnated component can be retained between the layers. In addition, if the oil-soluble hectorite is obtained by substitution of a quaternary ammonium ion that is a monovalent cation having the most organic side chains, it can exhibit high lipophilicity and, as a result, obtain a high effect. I can do it.

  The solvent used for the oil-soluble smectite is not particularly limited as long as it is an organic substance that can be dissolved. In addition to aliphatic hydrocarbons such as liquid oil, mineral oil such as mineral spirits, which are known as impregnating oils for calcined pencil cores, aromatic hydrocarbons Low polar organic substances such as ethanol, alcohols such as ethanol and propanol, polar organic substances such as glycols such as dipropylene glycol, tripropylene glycol and polypropylene glycol, amides, ketones and ethers can also be used. You may use these individually or in mixture of 2 or more types. The amount of oil-soluble smectite added is sufficient as long as it dissolves in the solvent. Although it depends on the kind of the solute solvent, it is preferably about 1% by weight to 10% by weight with respect to the solvent.

The method of impregnating the core with oil-soluble smectite is not limited. For example, the core is immersed in a solution in which oil-soluble smectite is dispersed. After immersion, the excess is removed with a centrifuge or the like to obtain a core body impregnated with oil-soluble smectite.
In addition, after immersing the core in a liquid in which oil-soluble smectite is dispersed in a low-boiling polar solvent, the solvent is volatilized by heating, and then the mineral oil and aromatic hydrocarbons that serve as the medium for the oil-soluble smectite are reduced. It is also possible to obtain a core body impregnated with oil-soluble smectite by immersing in a polar solvent and removing excess with a centrifuge after immersion.
At the time of impregnation, the core may be immersed in an impregnation component heated to about 100 ° C., or may be in a reduced pressure or pressurized state. Moreover, you may immerse, stirring.

Conventionally used constituent materials and manufacturing methods can be used without limitation for the core used as a medium for impregnating each of the above-described components used in the present invention.
Using various structural materials such as graphite and boron nitride, and clay and various synthetic resins as binders, as well as kneaders, Henschel mixers, colorants, pore forming materials, plasticizers, solvents, etc. It is obtained by uniform dispersion with a roll or the like, extrusion molding, and high-temperature firing at 800 ° C. or more and 1200 ° C. or less.
Specifically, synthetic resin such as clay, polyvinyl chloride, polychlorinated polyethylene, furan resin, polyvinyl alcohol, styrene resin, acrylic resin, urea resin, melamine resin, polyester resin is used as a binder, graphite, nitriding Constitutional materials such as boron, talc, mica, coloring materials such as organic pigments and inorganic pigments used as necessary, pore forming materials such as polyamide, polyethylene, polymethyl methacrylate (PMMA), dioctyl phthalate (DOP), After uniformly dispersing with a kneader, Henschel mixer, 3 rolls, etc. with a plasticizer such as dibutyl phthalate (DBP), water, alcohol, ketone, ester, aromatic hydrocarbon, etc. A white fired pencil is obtained.

EXAMPLES Next, although an Example is given and this invention is further demonstrated, this invention is not limited to these Examples.
(Preparation of fired core 1)
Vinyl chloride resin 40 parts by weight Graphite 50 parts by weight Carbon black 2 parts by weight Dioctyl phthalate 10 parts by weight Stearic acid 2 parts by weight Methyl ethyl ketone 30 parts by weight The above blend was blended sufficiently with a kneader and three rolls and then extruded into a thin line. Molded, heated to 300 ° C. in air, and further heated to 950 ° C. in an inert atmosphere to obtain a fired core body 1 having a core diameter of 0.57 mm.

Example 1
A Buchner funnel was prepared by dispersing 1-ethyl-3-methylimidazolium chloride (EMZ-C1, Shikoku Kasei Kogyo Co., Ltd.) in a 5% by weight aqueous solution of water-soluble montmorillonite (Wenger HVP, manufactured by Hojun Co., Ltd.). The oil-soluble smectite organically modified with a phosphonium salt was obtained by suction filtration using and drying at 100 ° C. by heating. The fired core 1 was immersed in a solution in which 3% by weight of this oil-soluble smectite was dissolved in dipropylene glycol. After 12 hours, the fired core 1 was pulled up, and excess impregnated components on the surface of the core were removed with a centrifuge to obtain a pencil core impregnated with oil-soluble smectite.

(Example 2)
In Example 1, a pencil lead impregnated with oil-soluble smectite was obtained in the same manner as in Example 1 except that water-soluble saponite (Smecton SA, manufactured by Kunimine Kogyo Co., Ltd.) was used instead of water-soluble montmorillonite. It was.

(Example 3)
In Example 1, a pencil lead impregnated with oil-soluble smectite was obtained in the same manner as in Example 1 except that water-soluble stevensite (Ionite, manufactured by Mizusawa Chemical Co., Ltd.) was used instead of water-soluble montmorillonite. It was.

Example 4
In Example 1, 1-methyl-3-n-propylimidazolium iodide (MPrZ-I, manufactured by Shikoku Kasei Kogyo Co., Ltd.) was used in place of 1-ethyl-3-methylimidazolium chloride. In the same manner as in Example 1, a pencil lead impregnated with oil-soluble smectite was obtained.

(Example 5)
A pencil lead impregnated with oil-soluble smectite in the same manner as in Example 1 except that water-soluble hectorite (Lucentite SWN, manufactured by Corp Chemical Co., Ltd.) was used instead of water-soluble montmorillonite in Example 1. Got.

(Example 6)
In Example 1, instead of 1-ethyl-3-methylimidazolium chloride, an alkyl primary amine salt (Nissanamine VBS, manufactured by Nippon Oil & Fats Co., Ltd.), a cationic surfactant, was dispersed. In the same manner as in Example 1, a pencil lead impregnated with oil-soluble smectite was obtained.

(Example 7)
In Example 1, instead of 1-ethyl-3-methylimidazolium chloride, an alkylpyridinium salt (1-butylpyridinium chloride, manufactured by Tokyo Chemical Industry Co., Ltd.), which is a cationic surfactant, was dispersed. Obtained a pencil lead impregnated with oil-soluble smectite in the same manner as in Example 1.

(Example 8)
In Example 1, in place of 1-ethyl-3-methylimidazolium chloride, a quaternary ammonium ion (NIKKOL CA-2450, manufactured by Nikko Chemicals), which is a cationic surfactant, was dispersed. Obtained a pencil lead impregnated with oil-soluble smectite in the same manner as in Example 1.

Example 9
A fired core in an oil-soluble hectorite (Lucentite SPN, manufactured by Coop Chemical Co., Ltd.) in which a part of the exchangeable cation is replaced with quaternary ammonium ions is dispersed in 3% by weight of tripropylene glycol. 1 was immersed. After 12 hours, the fired core 1 was pulled up, and excess impregnated components on the surface of the core were removed with a centrifuge to obtain a pencil core impregnated with oil-soluble smectite.

(Comparative Example 1)
3% by weight of water-soluble montmorillonite (Bengel HVP) was added to dipropylene glycol, and the fired core 1 was immersed while stirring with a stirrer. After 12 hours, the fired core 1 was pulled up, and excess impregnated components on the surface of the core were removed with a centrifugal separator to obtain a pencil core impregnated with the impregnated components.

(Comparative Example 2)
3% by weight of water-soluble hectorite (Lucentite SWN, manufactured by Corp Chemical Co., Ltd.) was added to dipropylene glycol, and the fired core 1 was immersed while stirring with a stirrer. After 12 hours, the fired core 1 was pulled up, and excess impregnated components on the surface of the core were removed with a centrifugal separator to obtain a pencil core impregnated with the impregnated components.

(Comparative Example 3)
As an extreme pressure additive solution, the fired core 1 was immersed in a 3 wt% spindle oil solution of molybdenum dithiocarbamate (molyvan 822, Sanyo Chemical Industries, Ltd.). After 12 hours, the fired core 1 was pulled up, and excess impregnated components on the surface of the core were removed with a centrifugal separator to obtain a pencil core impregnated with the impregnated components.

(Comparative Example 4)
After being immersed in polybutene heated to 100 ° C. (LV-50: kinematic viscosity at 250 ° C. and 250 mm ^{2 /} sec (c.St) for 12 hours, excess impregnated components on the core surface were removed with a centrifuge. A pencil lead impregnated with the impregnating component was obtained.

The handwriting density and fixability (at the time of rubbing and pressing) of the pencil lead obtained by the above zeros were measured. The concentration was measured according to JIS s 6005. The fixability at the time of rubbing is expressed as follows: the density of the writing part drawn by density measurement is α, the writing part is rubbed under a constant condition of 10 reciprocations with tissue paper under a vertical 500 g load, and the density of the dirty part outside the writing part is β. (1? Β / α) was obtained as a percentage. The smaller the value, the better the fixability during rubbing. The fixing property at the time of pressing is that the density of the writing portion drawn by density measurement is α, the drawing paper is overlapped on the writing portion, and the writing portion is rubbed under a constant condition of 10 reciprocations with a vertical 500 g load, When the density at which the writing line was transferred was γ, (1? Γ / α) was obtained as a percentage. The smaller the value, the better the fixability during pressing. The results are shown in Table 1.

Claims (4)

A pencil lead in which pores obtained by firing are impregnated with an impregnation component, wherein the impregnation component contains at least an oil-soluble smectite which is a swellable layered silicate. The oil-soluble smectite, which is a swellable layered silicate, is obtained by replacing the exchangeable cation between layers with an organic cation obtained from a cationic surfactant. The pencil lead described. The pencil lead according to claim 2, wherein the organic cation obtained from the cationic surfactant is a quaternary ammonium ion. The pencil lead according to any one of claims 1 to 3, wherein the oil-soluble smectite, which is a swellable layered silicate, is an oil-soluble hectorite.