DE3120241C2 - Unbaked colored leads or chalk and processes for their manufacture - Google Patents

Description

The invention relates to unfired colored leads or chalk, the binders, fillers, dyes as well possibly contain lubricants and / or other additives. With unfired colored leads or chalk like them, for example from DE-AS 24 42 983, DE-AS 23 52 065. US-PS 2? 84 164 and US-PS 20 75 223 were known as a binding agent so far in particular polyvinyl alcohol, polyvinylpyrrolidone, methyl cellulose, carboxymethyl cellulose, Gum arabic, dextrin, or sodium alginate are used.

The production of these leads or chalks usually took place in kneaders or compulsory mixers the binder was dissolved or swollen in a predetermined amount of water, that then the rest Components such as fillers, dyes or pigments, lubricants and / or waxes and possibly others Additives are mixed in and the plastic mass is homogenized in the rolling mill and kept at a constant level Water content were adjusted.

The water content is important for the consistency of the mass, as it affects the subsequent compaction and pressing, especially medium extrusion press, significantly affected.

The strand of mine emerging from the nozzle of the extruder is cut to the desired length, dried and, if necessary, impregnated with wax or oil.

The properties of the not yet dried leads have a major impact on the pressing and cutting speed as well as the drying conditions.

Although the previous unfired colored leads or chalk already had sufficiently good properties in

ίο show finished condition, there is a special one The disadvantage is that the processing or the overall production can only take place relatively slowly.

After the manufacturing jigs overall significantly would allow faster working speeds, it is with the previous color leads or -chalk not given without further ado to take full advantage of these more economical production possibilities.

In addition, the previously used binders are relatively expensive, so that the hereby made For this reason, mines become relatively expensive.

In particular, the shear loads acting on the undried (green) lead when it is pressed through the outlet nozzle of the extrusion press and when cutting to the finished length produce irreversible changes or deformations of the green mine if certain pressing or cutting speeds are exceeded will.

The main reason for this can be seen in the fact that the binders used hitherto are in Connection with the other components, such as silicates, oxides, carbonates and / or other additives no particularly solid mines result in their individual production phases.

It is therefore the object of the present invention to create unfired colored leads or chalk that consists of extremely inexpensive raw materials and in a particularly economical way with very high production speeds and can be produced easily using the methods that have been customary up to now and are therefore particularly inexpensive Result in end products.

According to the invention, this object is achieved in that the leads are used exclusively or additionally as binders (to conventional binders as a partial replacement), contain polygalactomannan ether.

Polygalactomannans can be chemically modified in various ways. However, they are particularly suitable in their etherified form as polygalactomannic agents for the use according to the invention.
The production and use of polygalactomannan and especially of polygalactomannan ether was generally known for a long time and is z. B. in the company brochure "Guar and Guar Derivatives with Diverse Applications" by Meyhall and in the book "Industrial Gums, Polysaccharides and their Derivates" by RL Whistler, Academie Press Inc., New York, London, 1973, page 17 to 41, in particular pages 30 to 34, and in US Pat. No. 3,326,890, comprehensively described.

From this, however, there was no evidence whatsoever that polygalactomannan and especially in his ethereal form, would be suitable for mines.

It was therefore certainly not evident from this that these materials were used especially as binders for unfired Mines could be used in an extremely advantageous manner and, above all, their manufacturing capabilities would improve.

The production of colored leads according to the invention or -chalk is done according to a preferred method because-

3 4

by that initially in a kneader the per se The processing is also carried out according to the conventional Polygalactomannan ether is dissolved in water, control example, with methyl cellulose as the second that in this solution the remaining components of the mixture binders, together with the polygalactomannane knelei and that after complete homoether is added and dissolved, genization and setting of the 5

the required water content the colored leads or production example

-chalk pressed in a known manner, dried
and, if necessary, impregnated. The water is poured into a mixer or kneader

This way, under exclusive or partial fills. Then the polygalactomannan ether is used herein The binder according to the invention was stirred and completely dissolved in the water Refills have a particularly high dry flex viscous solution is the kaolin or the filler uniqueness and at the same time also high wet breaking strength mixed. The present mass has no structure in the raw (green) state, so that the fcrmelle ture viscosity and no more thixotropic. In they who-making in presses or extruders also with the other components, such as dyes, sliding heights Press speeds of, for example, more is medium, etc., kneaded

than 3 m / sec. Which occur during cutting after complete homogenization of these

Shear loads tend to result in such mines. Mass is also required for further processing to no deformation, so that the water content is admitted by evaporation. That these mines also thereby from with the exclusively subsequent pressing of the mines or chalks as well Refills 20 produced with conventional binders, which are dried between 80 and 150 ° C., are positive lift up. known way.

The beneficial effect of the invention
The binder is mainly due to its in aqueous
Phase of particularly good cohesion, especially towards
Kaolin or clay, resulting in 25
a plastically deformable mass with high tensile and shear strength results from these two components.

For use according to the invention in lead masses, the polygalactomannan ether is said to be advantageous
a molecular weight between 1,000 and 350,000 and 30
an average degree of substitution between 0.1
and 2.8.

The invention is explained in more detail below with a few exemplary embodiments. The quantities
are understood here as percentages by weight. 35

Mixture example 1

5% dye (phthalocyanine pigment)

8.3% aluminum stearate 40

61.7% kaolin

83% polygalactomannan ether

(Degree of substitution 0.8, MW 120,000)
16.7% water

45
The processing takes place according to the production example.

Mixture example 2

15% water _i0

8% polygalactomannan ether

(Degree of substitution 0.45, MG 100,000)
60% kaolin

6% color pigment
11% calcium stearate 55

The processing takes place here as well according to the production example.

Mixture example 3 5% Color pigment 8th% Aluminum stearate 62% kaolin 4% Polygalactomannan ether 4.5% Methyl cellulose 16.5% water

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Claims (6)

Patent claims: 1. Unburned colored leads or chalk based on binders, fillers, dyes and optionally lubricants and / or other additives, characterized in that they are exclusive or contain etherified polygalactomannan as an additional binder. 2. Unburned colored leads or chalks according to claim 1, characterized in that the polygalactomannan ether has a molecular weight of 1,000 to 350,000. 3. Unburned colored leads or chalk according to one of claims 1 or 2, characterized in that that the polygalactomannan ether has an average degree of substitution of 0.1-2.8. 4. Unburned colored leads or chalk according to one of the preceding claims, characterized in that that they contain silicate fillers, especially kaolin or clay. 5. Unburned colored leads or chalk according to one of the preceding claims, characterized in that that they consist of a base material consisting of 3 to 10% by weight of color pigment; 5 up to 15% by weight aluminum stearate, 40 to 80% by weight kaolin, 4 to 15% by weight polygalactomannan ether and 10 to 20% by weight of water. 6. Process for the production of unfired colored leads and chalk according to one of the preceding Claims 1 to 5, characterized in that the polygalactomannan ether is initially used in a kneader is dissolved in water that the remaining components of the mixture are kneaded into this solution and that after complete homogenization and by evaporation, the adjustment of the for the further processing of the required water content the colored leads or crayons in per se known Pressed, dried and, if necessary, impregnated.