GRAPHITE LEAD OR GRAPHITE CHALK OR GRAPHITE BLOCK, PENCIL WITH GRAPHITE LEAD, AND METHOD FOR PRODUCING A GRAPHITE LEAD OR GRAPHITE CHALK OR GRAPHITE BLOCK

Abstract

The invention relates to a graphite lead or graphite chalk or graphite block for drawing and painting, having a base body made of a base mass at least containing a cellulose-based binding agent, a filler, and graphite, the base body being impregnated with a waterproof preparation mixture containing at least a mixture of iso-paraffins and n-paraffins or a water-soluble preparation mixture containing at least a water-soluble emulsifier.

The invention also relates to a pencil with such a graphite lead and to a method for producing a graphite lead or graphite chalk or a graphite block.

Claims

1. Graphite lead or graphite chalk or graphite block for drawing and painting, comprising a base body made of a base mass containing at least one cellulose-based binding agent, a filler, and graphite, wherein graphite is contained in a proportion between 4 and 30% by weight, and wherein the base body is impregnated with a waterproof preparation mixture containing at least a mixture of iso-paraffins and n-paraffins or with a water-soluble preparation mixture containing at least a water-soluble emulsifier.

2. Graphite lead or graphite chalk or graphite block according to claim 1, wherein the filler is an inorganic filler, in particular kaolin.

3. Graphite lead or graphite chalk or graphite block according to claim 1, wherein the binding agent is contained in a proportion between 0.5 and 6% by weight.

4. Graphite lead or graphite chalk or graphite block according to claim 1, wherein the filler is contained in a proportion between 40 and 90% by weight.

5. Graphite lead or graphite chalk or graphite block according to claim 1, wherein the graphite has a grain size distribution x.sub.10=0.9 μm, x.sub.50=3.3 μm, x.sub.90=14.6 μm, and a carbon content of 88 to 92% by weight.

6. Graphite lead or graphite chalk or graphite block according to claim 1, wherein the base mass contains carbon black and wherein the proportion of carbon black is in particular a maximum of 35% by weight.

7. Graphite lead or graphite chalk or graphite block according to claim 1, wherein a lubricant and/or a surfactant and/or an emulsifier is contained as at least one additive and wherein the proportion of additives is in particular a maximum of 5% by weight.

8. Graphite lead or graphite chalk or graphite block according to claim 1, wherein the mixture of iso-paraffins and n-paraffins is contained in the waterproof preparation mixture in a concentration between 10 and 50% by weight.

9. Graphite lead or graphite chalk or graphite block according to claim 1, wherein the waterproof preparation mixture contains a fatty acid, in particular stearin or stearic acid.

10. Graphite lead or graphite chalk or graphite block according to claim 9, wherein the fatty acid is contained in the waterproof preparation mixture in a concentration between 25 and 70% by weight.

11. Graphite lead or graphite chalk or graphite block according to claim 1, wherein the waterproof preparation mixture contains triglycerides and/or further wax-like components, in particular fatty acid derivatives or polyolefin waxes or ethylene vinyl acetate wax.

12. Graphite lead or graphite chalk or graphite block according to claim 11, wherein the triglycerides or further wax-like components are contained in the waterproof preparation mixture in a maximum concentration of 40% by weight.

13. Pencil having a graphite lead according to claim 1, in particular a pencil with a sheathing made of wood or a wood substitute material, or a mechanical pencil.

14. Method for producing a graphite lead or graphite chalk or graphite block, comprising the following steps: a) Producing a base body from a base mass at least containing a cellulose-based binding agent, a filler, and graphite, in particular by a1) Mixing and homogenizing at least the binding agent, the filler, and the graphite to form the base mass, a2) Adding water to the base mass and homogenizing the mixture of base mass and water, a3) Extruding the base mass to form graphite lead strands and/or graphite chalk strands and/or graphite blocks, a4) Drying the extruded graphite leads and/or graphite chalks and/or graphite blocks, b) Impregnating the base body in a waterproof preparation mixture containing at least a mixture of iso-paraffins and n-paraffins or in a water-soluble preparation mixture containing at least a water-soluble emulsifier, c) Removing excess preparation mixture.

Description

EXAMPLE 1

[0046] Graphite block with dimensions of approx. 50 mm×20 mm×10 mm, degree of hardness 14B: [0047] Carboxymethyl cellulose (CMC100): 2.5% by weight [0048] Kaolin: 51.5% by weight [0049] Graphite: 19% by weight [0050] Carbon black: 26.7% by weight [0051] Additive, Genapol PF 80 FP.sup.1): 0.3% by weight

[0052] The preparation mixture used to produce the graphite block according to Example 1 contains:

TABLE-US-00001 Stearic acid.sup.2) 60% by weight Iso-paraffin/n-paraffin wax mixture.sup.3) 15% by weight Triglycerides.sup.4) 25% by weight

[0053] Further Examples 2 through 5, each for producing a graphite lead having a diam-eter of about 3 mm, but with different degrees of hardness, are summarized in the following Table 1 (all information is provided in percent by weight):

TABLE-US-00002 TABLE 1 Example 2: Example 3: Example 4: Example 5: Degree of Degree of Degree of Degree of hardness HB hardness 8B hardness 12B hardness 14B Cellulose bind- 4 4 4 4 ing agent CMC 100 Kaolin 86.0 65.4 55.1 49.95 Graphite 10 15.6 18.4 19.8 Carbon black 0 15.0 22.5 26.25

[0054] A waterproof preparation mixture having the following composition is used for each of Examples 2 through 5: [0055] Stearin.sup.5): 40% by weight [0056] Iso-paraffin/n-paraffin mixture.sup.3): 30% by weight [0057] Triglycerides.sup.4): 30% by weight

[0058] After the graphite leads or graphite block was produced, strokes were produced on a painting base, in this case paper, and assessed with regard to the stroke properties.

[0059] The graphite leads create a matte, uniform stroke on paper. The gloss value was measured according to the following method: [0060] Device: Micro-TRI-gloss from BYK 60° angle. [0061] Reference values: 95 GP highest gloss value [0062] 2 GP lowest gloss value [0063] Color density measured with: X-Rite exact [0064] Reference value: 1.90 color density for optimal black

[0065] The results of the measurement of the graphite leads with a composition according to the above Examples 3 and 5 and of three comparison leads with a degree of hardness of 8B are summarized in Table 2 below.

TABLE-US-00003 TABLE 2 Color density, black Gloss Faber-Castell matte 1.46  7 GP black, 8B (Example 3) Faber-Castell matte, 14B 1.63  8 GP (Example 5): Faber-Castell standard 1.32 19 GP lead Castell 8B Competitor product, 1.33 16 GP made in Germany, de- gree of hardness 8B: Competitor product, Asia, 1.30 23 GP matte, 8B:

[0066] Based on these objective results of the measurement, it can be demonstrated that in particular the type of paraffin used together with the type of graphite used produces a graphite lead that has a significantly reduced gloss level (7 or 8 GP) compared to commercially available standard leads (16 to 23 GP).

[0067] Furthermore, the stroke produced with the inventive graphite leads provides a stronger and more opaque black than with the comparison leads.

[0068] Product Names/Manufacturer:

[0069] 1) Clariant AG, D-65929 Frankfurt am Main

[0070] 2), 3), 4), 5) Wachs- and Ceresin Fabriken Th. C. Tromm GmbH, Feuerstrasse 7 to 17, D-50735 Cologne