JPS59210981A - Pencil lead - Google Patents

Abstract

PURPOSE:To provide a non-burned pencil lead having high strength and toughness, prepd. by adding a bismaleimide/triazine resin as binder. CONSTITUTION:A mixt. of a colorant (e.g. carbon black), an extender (e.g. talc), a wax (e.g. polyethylene wax), a solvent (e.g. acetone) soln. of bismaleimide/ triazine resin as binder, etc. is formed into pencil lead form by extrusion and the formed lead is heat treated at 180 deg.C or higher for evaporation of the solvent and postcure of the binder. EFFECT:The non-burned pencil lead insures smooth writing and has high tensile, flexural and impact strengths.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a non-fired pencil lead mainly used as a lead for colored pencils, a lead for synthetic wooden ladles, a lead for a mechanical pencil, etc. The object of the present invention is to provide a non-fired pencil lead that is extremely superior in mechanical strength such as strength.

Conventional non-fired pencil leads are made of polyvinyl alcohol, polyvinyl chloride, vinyl chloride copolymer, polystyrene, styrene copolymer, and cellulose resin.

The binder is one or more organic polymeric substances selected from epoxy resin, furan resin, etc., and a coloring agent, wax, and an extender such as an inorganic filler, and if necessary, a plasticizer for the binder. Alternatively, it has been produced by extrusion molding an extrusion molding material made of a blended composition to which a solvent or the like has been added, then volatilizing the plasticizer or solvent, and then subjecting it to heat treatment if necessary.

The unfired pencil lead thus produced uses an organic polymer substance instead of the carbide binder in the fired pencil lead.

Because wax is added to the blended composition for the purpose of imparting a smooth writing feel and adhesion to paper to this unfired pencil lead, sufficient mechanical strength is not developed, and it is not suitable for practical use. It had drawbacks such as being easy to break.

In order to improve the strength of a non-fired pencil lead made of a blended composition in which this organic polymer substance is bonded;'sl'J and wax is added, fibrous graphite or fibrous graphite or A method of adding and using carposi black (Japanese Patent Publication No. 4818347) A method of adding and using needle-like crystals of titanium potassium in the form of short fibers or acicular crystals (Japanese Patent Publication No. 52-88419) 0.0.1
Methods using special colorants or extenders have been proposed, such as the method of using extremely ridged extenders of -0.1μ (Japanese Unexamined Patent Publication No. 54-121829), but none of these methods yield results. The strength of the unfired pencil lead is not sufficient. The present invention uses bismaleimide triazine resin as a binder made of an organic polymeric substance, and its manufacturing method is different from that of the conventional unfired pencil lead. It can be done in exactly the same way.

In the present invention, as a binder in the compounded composition (bismaleimide/triazine resin contained in two) is a highly heat-resistant addition polymerized polyimide resin having imide groups in the molecule and containing two main components: bismaleimide and triazine monomer. Therefore, in the present invention, it is preferable to use a material having a relatively high molecular weight and exhibiting a high viscosity when melted.

The non-fired pencil lead of the present invention is produced by mixing, extrusion molding, and heat-treating a blended composition consisting of a specific bismaleimide triazine resin as a binder, a coloring agent, an extender, a wax, etc. However, the solvents for the bismaleimide/triazine plum fat added thereto are acetone and mecal ether titone in order to make these blended compositions uniform in R14 & 14 and easily extruded.

IJ・Methylpyrrolidone, dimethylformamide.

Examples include dimethylacetamide, and its volume i'
; 6H methylpyrrolidone is suitable for one person's IQ, in terms of ease of use, workability, etc.

In addition, "Pilgrimage 511" includes black pigments such as graphite and carbon black, white pigments such as titanium chloride, and each 4.+!
Although any material size can be used, in the manufacturing process of the non-fired pencil lead of the present invention, the composition 1↓
Mix A 1ξ of paraboloids and heat treatment at 180℃ or higher after extrusion molding 1
4I! It is recommended to use organic pigments with excellent heat resistance because the bath agent is exposed to 44°C (light) and at the same time the bismaleimide triazine resin added and blended as a binder is post-cured. Preferably, the bismaleimide triazine resin itself as a binder has a light brown color.

It is preferable to use pigments with high hiding power.

Extending materials such as talc, sericite, kaolinite, bentonite, wollastonite, charcoal, calcium, and boron nitride can be used as they are.

Of course, two or more kinds of extenders can be mixed and used.

In addition, the waxes added and blended to give the writing instrument a smooth writing feel and ensure adhesion to the surface of the writing paper include gold soap, wood wax, hydrogenated castor oil, and acclimatized wax. kind.

Polyethylene wax and polypropylene wax can be used (14-1), and of course you can combine two or more waxes together and use IH, but for the same reason as θ), first use an organic pigment J shell. Those having a high melting point and good thermal stability are preferred.

Hereinafter, the specific structure and effects of the present invention will be explained using manufacturing examples.

Example 1 (2) Carbon black 20! 'L
;Fusi 1chi IS (, i) Talc 3
5 Kei 1 Todai 1 s The blended composition consisting of the above (11 to (4)) was mixed and kneaded under heating using two rolls, and after adjusting the N-methylpyrrolidone content, a plunger type extruder was used. The resulting molded product is heated to 110°C to volatilize most of the N-methylpyrrolidone.Then, it is heat-treated at 180°C for 8 hours to form bismaleimide-triazine. The resin is cured to obtain a black-core 0.5-unfired pencil lead for matte-treated polyester film.

1.The pencil lead you were asked about has a density equivalent to HB in terms of pencil lead hardness.2
Based on JIS S-6019 (the same applies hereinafter)
The bending strength is 17,000 seams, and the brush feel is smooth.

Example 20% N-methylpyrrolidone solution 80 parts by weight (2) Perylene red 20 beats≦
(3) Polypropylene wax (Sanyo Chemical (Viscol made by 1 Wolf) 15ri 111 parts (4) Tarri
45
5 parts of the above-mentioned blended composition (11 to (4)) were mixed and mixed under heating using two rolls, and the N/l/pyrrolidone content was adjusted. Extrusion molding was performed at 100°C using a plunger type extruder, and the resulting molded product was heated to 110°C to volatilize most of the N-methylpyrrolidone.

The bismaleimide-triazine resin is cured by heat treatment at 180"C for 8 hours to obtain a red 0.5 scale unfired core. The bending strength of the resulting unfired core is 15000 gr.
im2 has a smooth writing feel.

The unfired core of the present invention has a structure as shown above,
By using a bismaleimide triazine resin as an organic polymeric material as a binder in a composition for molding unfired pencil leads.

It has the same pure ragana '41 feel as conventional unfired pencil lead,
Furthermore, a non-fired pencil lead can be obtained which has significantly superior mechanical strengths such as tensile strength, bending strength, and impact strength.

Claims (1)

[Claims] Bismaleimide triazine resin is added as a binder,
It is characterized by the fact that it is formulated with a non-fired pencil lead.