Method for producing powder leads and products produced therewith

Abstract

A method for producing a powder lead is disclosed, wherein at least one colourant, at least one filler and at least one binder are mixed with a carrier liquid, leads are shaped from the wet compound, the leads shaped in step b) are guided through a chamber in which they are exposed to a pulverulent covering agent, and the powdered leads are guided into a drying apparatus and dried therein.

Claims

1. A method for producing a powder lead, comprising: a. mixing at least one colourant, at least one filler, and at least one binder with a carrier liquid to form a wet compound, b. shaping leads from the wet compound to form shaped leads including a lead surface, c. guiding the shaped leads through a chamber, d. exposing the shaped leads to a pulverulent covering agent in the chamber to form powdered leads covered with a pulverulent covering on the lead surface, wherein the shaped leads are moist during the exposing of the shaped leads to the pulverulent covering agent, e. guiding the powdered leads with the pulverulent covering into a drier, and f. drying the powdered leads with the pulverulent covering in the drier.

2. The method according to claim 1, wherein the at least one colourant comprises at least one pigment present in powder form.

3. The method according to claim 1, wherein the pulverulent covering agent is a wax, a polymer, or a wax and a polymer, and wherein the pulverulent covering agent melts at a temperature of from 50° C. to 120° C.

4. The method according to claim 1, wherein the shaped leads are exposed to the pulverulent covering agent in a proportion of from 0.5% to 10% by weight, based on the weight of the shaped leads.

5. The method according to claim 1, wherein the shaping leads comprises shaping the leads in an extrusion apparatus.

6. The method according to claim 1, wherein, during the exposing of the shaped leads, the shaped leads are powdered with the pulverulent covering agent using a corona gun.

7. The method according to claim 1, wherein the drying of the powdered leads with the pulverulent covering comprises drying at a temperature of from 50° C. to 120° C. over a period of from 8 hours to 24 hours.

8. The method according to claim 1, further comprising covering the powdered leads with the pulverulent covering with a shrink sleeve.

9. A powder lead obtained by the method that comprises the steps of: a. mixing at least one colourant, at least one filler, and at least one binder with a carrier liquid to form a wet compound, b. shaping leads from the wet compound to form shaped leads including a lead surface, c. guiding the shaped leads through a chamber, d. exposing the shaped leads to a pulverulent covering agent in the chamber to form powdered leads covered with a pulverulent covering on the lead surface, wherein the shaped leads are moist during the exposing of the shaped leads to the pulverulent covering agent, e. guiding the powdered leads with the pulverulent covering into a drier, and f. drying the powdered leads with the pulverulent covering in the drier.

10. The method according to claim 1, wherein the pulverulent covering agent is comprised of particles having a particle size of from 0.01 μm to 100 μm.

11. The method according to claim 1, wherein the pulverulent covering agent is comprised of particles having a particle size of from 10 μm to 40 μm.

12. The method according to claim 1, wherein the pulverulent covering is only disposed around the powdered leads.

13. The powder lead of claim 9, wherein the pulverulent covering agent is a wax, a polymer, or a wax and a polymer, and wherein the pulverulent covering agent melts at a temperature of from 50° C. to 120° C.

14. The powder lead of claim 9, wherein the shaped leads are exposed to the pulverulent covering agent in a proportion of from 0.5% to 10% by weight, based on the weight of the shaped leads.

15. The powder lead of claim 9, wherein the shaping leads comprises shaping the leads in an extrusion apparatus.

16. The powder lead of claim 9, wherein, during the exposing of the shaped leads, the shaped leads are powdered with the pulverulent coveting agent using a corona gun.

17. The powder lead of claim 9, wherein the drying of the powdered leads with the pulverulent covering comprises drying at a temperature of from 50° C. to 120° C. over a period of from 8 hours to 24 hours.

18. The powder lead of claim 9, wherein the method further comprises the step of covering the powdered leads with the pulverulent covering with a shrink sleeve.

19. The powder lead of claim 9, wherein the pulverulent covering agent is comprised of particles having a particle size of from 0.01 μm to 100 μm.

20. The powder lead of claim 9, wherein the pulverulent covering agent is comprised of particles having a particle size of from 10 μm to 40 μm.

21. The powder lead of claim 9, wherein the pulverulent covering is only disposed around the powdered leads.

22. The powder lead of claim 9, wherein the at least one colourant comprises at least one pigment present in powder form.

Description

EXAMPLE 1

(1) A compound for a powder lead was produced. To this end, a dry phase composed of silica, kaolin, mica and/or mica-like constituents and polymethyl methacrylate, pigments and pearls with a binder phase containing magnesium aluminium silicate, align, and sorbitan laurate and preservatives was kneaded with water to form a moist compound. Said moist compound was guided into an extrusion apparatus and, by means of pressure through the cylinder, leads were pressed out of the apparatus.

(2) Core length: 627 mm

(3) Cutting interval: 2 s per 627 mm, or 313.5 mm/s

(4) The leads pressed out of the extrusion apparatus were then conducted into a chamber in which there was permanent circulation of fine-particulate hydrogenated castor oil having a melting range of 85-88° C. as covering agent, with the result that the lead was uniformly covered by this powder. The layer thickness of the cover substance was set by means of the amount of covering agent in the chamber and the circulation rate as well as the rate of movement of the leads. Coating was achieved by using a corona gun, as is also used for the application of automotive paint. Charge strength and flow-through speed were set such that the desired layer thickness was achieved.

(5) After leaving the chamber, the powdered leads were dried to constant weight in a drying oven at a temperature of 90° C. for at least 8 hours.

(6) The dried leads were then cut to the desired length and subsequently provided with a shrink sleeve.

(7) In the case of leads which were produced in a comparative test with the same composition and the same method, but without addition of the covering agent, it was not possible to overlay a shrink sleeve, since the leads crumbled. In addition, there were problems with cutting to length.

(8) The finished leads were then inserted into shell blanks made of wood and glued. After decoration and sharpening, finished pencils were obtained which could be applied very easily to the skin and provided a strongly coloured application, with the application being experienced as highly pleasant.

EXAMPLE 2

(9) Lead compounds were produced from the ingredients listed in Table 1 below.

(10) TABLE-US-00001 TABLE 1 NAME OF RAW MATERIAL [INCI] PARTS BY WEIGHT Pigments 71.650 Water 30.001 Filler, e.g. synthetic fluorphlogopite, kaolin 20.410 Moisturizer, e.g. pentylene glycol 17.970 Silica 10.480 Optical modifier, e.g. polymethyl methacrylate beads 10.470 Plasticizer, e.g. caprylyl glycol; dipropylene glycol; 1.899 glyceryl caprylate Preservative, e.g. dehydroacetic acid 0.800 Emulsifier, e.g. sorbitan laurate 0.610 Thickener, e.g. Mg Al silicate, algin 0.500 pH modifier, e.g. citric acid 0.420 Flavourings, e.g. triethyl citrate 0.407 TOTAL AMOUNT 165.617

(11) Leads having a diameter within the range from 3.77 mm to 4.08 mm were extruded from the lead compound, with the upstream pressure being within a range from 55 to 65 bar. The speed of the extruded lead strand was about 310 mm s.sup.−1. The covering agent was electrostatically charged with a voltage of 45 kV and at a current of 4.5 μA. The electrostatically charged covering agent adhered upon contact with the lead strand. Non-adherent covering agent was sucked off in the chamber. After leaving the chamber, the covered lead strand was cut to length, yielding lead pieces having a length of 627 mm each. The lead pieces were placed onto a metal sheet and dried in a drying cabinet at 90° C. for 16 hours. After drying, the leads had a diameter within the range from 3.85 to 3.95 mm.

(12) As described in Example 1, the leads were inserted into shell blanks and glued. Using the pencils obtained, a line was drawn on skin on a test person. The application was experienced as highly pleasant. The line was strongly coloured.