Refill for writing, drawing and/or painting devices and method for the production thereof

Abstract

A polymer-bound refill for writing, drawing and/or painting devices, in particular for pencils or coloured pencils, including at least one binder, at least one wax, at least one colouring agent and at least one filler. The refill includes polylactide as binder.

Claims

1. A polymer-bonded refill for writing, drawing and/or painting tools, comprising: a binder; a wax; graphite as a colorant; and a filler, wherein the filler includes graphite, wherein the binder is formed by 10-25% by weight of polylactide based on weight of the entire polymer-bonded refill composition, wherein the polymer-bonded refill is a pencil lead refill and includes the following: TABLE-US-00009 5% to 15% by weight wax 0.1% to 2.5% by weight palm oil remainder graphite.

2. The polymer-bonded refill as claimed in claim 1, wherein the wax is at least one wax selected from the group consisting of fatty acids, stearates, montan waxes, amide waxes and paraffin waxes.

3. The polymer-bonded refill as claimed in claim 1, wherein the wax is ethylene-bis-stearamide (EBS) and/or calcium stearate.

4. A method for manufacturing the polymer-bonded refill as claimed in claim 1, comprising the steps of: mixing and granulating the binder, the wax, the colorant and the filler to form a refill granulate; and extruding the refill granulate to form the polymer-bonded refill.

5. The method according to claim 4, including extruding the refill granulate at a temperature in a range of 120° C. to 200° C.

Description

SUMMARY AND DESCRIPTION OF THE INVENTION

(1) Thus, the object of the invention is to provide a refill for writing, drawing and/or painting which does not suffer from the disadvantages mentioned above, and which in particular can be produced without being dependent on crude oil, but purely from renewable and degradable binders/polymers without compromising the primary properties of being capable of being sharpened, coloration, strength, coverage and erasability of the refill.

(2) The object is accomplished by substituting crude oil-based polymers with polylactides. Thus, a polymer-bonded refill is provided for writing, drawing and/or painting tools, in particular for pencils or coloured pencils which comprises at least one binder, at least one wax, at least one colorant and at least one filler, wherein the refill comprises polylactide as the binder.

(3) Polylactic acid or PLA is a synonym for polylactide. The frequently used abbreviation PLA is derived from the English term “polylactic acid”.

(4) Surprisingly, it has been shown that by replacing crude oil-dependent polymers with polylactides, the properties, for example the capability of being sharpened, coloration, strength, coverage and erasability of a refill are not compromised, but its manufacture is independent of crude oil. In this manner, the manufacturing costs of the refill are no longer dependent on the prices and availability of crude oil. In addition, a refill manufactured in this manner degrades more quickly and manufacturing it saves on the consumption of naturally occurring, non-renewable resources.

(5) The proportion of polylactide in the refill composition is in the range 10-60% by weight, preferably in the range 10% to 40% by weight and particularly preferably in the range 10-25% by weight.

(6) A polymer-bonded refill composed of the following:

(7) TABLE-US-00001 10% to 60% by weight polylactide 2% to 25% by weight wax 15% to 70% by weight filler 0 to 5% by weight palm oil 0 to 30% by weight colorant
has been shown to be advantageous.

(8) Advantageously, the at least one wax is at least one wax from the group comprising fatty acids, stearates, montan waxes, amide waxes and paraffin waxes. Mixtures of two or more waxes may also be employed.

(9) Particularly preferably, the at least one wax is calcium stearate and/or an ethylene-bis-stearamide (EBS).

(10) Very good results have been obtained with coloured refills when ethylene-bis-stearamide (EBS) is used. Using calcium stearate in lead pencil refills produces very good results.

(11) Advantageously, the at least one filler is at least one filler from the group comprising graphite, hexagonal boronitride, phyllosilicates, chalk, barite, coloured pigments and/or non-coloured pigments.

(12) Preferably, for pencil lead refills, graphite or graphite in combination with carbon black is used as the colouring filler. For coloured pencil refills, combinations of white or uncoloured fillers such as hexagonal boronitride, phyllosilicates etc., with colouring pigments such as azo pigments, phthalocyanines, dioxazines, quinacridones, iron oxides, carbon black, graphite, ultramarine, iron-cyano complexes have proved to be advantageous.

(13) A preferred composition for a pencil lead refill comprises the following:

(14) TABLE-US-00002 10% to 60% by weight polylactide 2% to 25% by weight wax 0 to 5% by weight palm oil remainder graphite

(15) In particular, a pencil refill is composed of the following:

(16) TABLE-US-00003 10% to 25% by weight polylactide 5% to 15% by weight wax 0.1% to 2.5% by weight palm oil remainder graphite

(17) An exemplary formulation for a pencil lead refill comprises the following:

(18) TABLE-US-00004 polylactide 20% by weight calcium stearate  9% by weight palm oil  1% by weight graphite remainder

(19) A further exemplary formulation for a pencil lead refill may have the following composition:

(20) TABLE-US-00005 polylactide 38% by weight calcium stearate  7% by weight ethylene-bis-stearamide  5% by weight palm oil  1% by weight graphite remainder

(21) The graphite listed in the examples may act as the colorant for pencil lead refills. Similarly, however, combinations of graphite and carbon black may also be employed.

(22) A composition for a coloured pencil refill comprises the following:

(23) TABLE-US-00006 10% to 60% by weight polylactide 2% to 25% by weight wax 1% to 30% by weight colorant remainder graphite

(24) In particular, a coloured pencil refill comprises the following:

(25) TABLE-US-00007 10% to 25% by weight polylactide 10% to 20% by weight wax 2% to 20% by weight colorant remainder graphite

(26) An exemplary formulation for a coloured pencil refill comprises the following:

(27) TABLE-US-00008 polylactide 15% by weight ethylene-bis-stearamide 13% by weight pigments  7% by weight fillers 65% by weight

(28) Coloured and/or non-coloured pigments may be employed as the colouring agent in coloured refills. Examples of pigments of this type are azo pigments, phthalocyanines, dioxazines, quinacridones, iron oxides, carbon black, graphite, ultramarine and iron-cyano complexes.

(29) An extrusion method has been shown to constitute an advantageous method for the manufacture of a polymer-bonded refill in accordance with the invention.

(30) In particular, the refill in accordance with the invention is manufactured by carrying out the following steps: mixing and granulating all of the components for the formulation of the refill in order to form a refill granulate extruding the refill granulate at a temperature in the range 120° C. to 200° C. in an extruder through a suitable die in order to form continuous refill rods cooling and solidifying the continuous refill rod, and cutting the continuous refill rod to final length, in particular to the required length of the pencil lead.

(31) Depending on the extrusion head, the cross-section of the refill may have any form—round, square or combinations thereof. Furthermore, it is possible to carry out multiple co-extrusion of various refill formulations in one extrusion head in order to bind a multi-component refill.

(32) Furthermore, a suitable co-extrusion method may be employed in order to extrude the refill granulate with other polymer-bonded materials so as to form a complete pencil lead.