Coloring pencil lead for synthetic pencil based on biopolymers blends

Inventor: Julien Gouerec (Clichy Cedex, FR)

Assignee: SOCIÉTÉ BIC

B43K19/18 B43K19/02 C08L67/04 C09D13/00

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Quick Facts

Patent No.: US 12691703
App. No.: 18/247,207
Granted: Jul 28, 2026
Kind: B2

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Abstract

The present invention relates to a polymer-based extendable lead or refill for writing, drawing and/or painting tools comprising a binder comprising a mixture of polylactide with at least one polymer having a flexural modulus inferior to the flexural modulus of polylactide and at least one filler. It also relates to writing, drawing and/or painting tool, advantageously a pencil, comprising lead or a refill according to the invention and to the use of a binder comprising a mixture of polylactide with at least one polymer having a flexural modulus inferior to the flexural modulus of polylactide according to the invention to improve the vividness of polymer-based extrudable lead or refill for writing, drawing and/or painting tools.

Claims (28)

1 . A polymer-based lead or refill for writing, drawing and/or painting tools, the polymer-based lead or refill comprising, based on a total weight of the polymer-based lead or refill:

5 wt. % to 48 wt. % of a polylactide binder;

2 wt. % to 45 wt. % of at least one polymer binder, other than the polylactide binder, having a flexural modulus inferior to the flexural modulus of the polylactide binder;

5 wt. % to 50 wt. % of at least one filler;

1 wt. % to 30 wt. % of at least one coloring agent, other than the at least one filler; and

3 wt. % to 40 wt. % of at least one slip agent and/or 3 wt. % to 40 wt. % of at least one wax;

wherein a total amount of the polylactide binder and the at least one polymer binder is 20 wt. % to 50 wt. %, based on the total weight of the polymer-based lead or refill; and

wherein the polymer-based lead or refill is extrudable.

2 . The polymer-based lead or refill according to claim 1 , wherein the at least one polymer binder has a flexural modulus <3000 MPa measured according to standard ISO 178:2019.

3 . The polymer-based lead or refill according to claim 1 , wherein the at least one polymer binder is selected from the group consisting of polyethylene (PE), poly(butylene adipate-co-terephtalate) (PBAT), poly(butylene succinate) (PBS), a starch-based polymer, and mixtures thereof.

4 . The polymer-based lead or refill according to claim 1 , wherein the at least one polymer binder is a starch-based polymer.

5 . The polymer-based lead or refill according to claim 1 , wherein a total amount of the polylactide binder and the at least one polymer binder is 30 wt. % to 40 wt. %, based on the total weight of the polymer-based lead or refill.

6 . The polymer-based lead or refill according to claim 1 , wherein the at least one polymer binder is present in an amount of 5 wt. % to 20 wt. %, based on the total weight of the polymer-based lead or refill.

7 . The polymer-based lead or refill according to claim 1 , wherein the polylactide binder is present in an amount of 20 wt. % to 30 wt. %, based on the total weight of the polymer-based lead or refill.

8 . The polymer-based lead or refill according to claim 1 , wherein a weight ratio of the polylactide binder to the at least one polymer binder ranges from 0.2 to 20.

9 . The polymer-based lead or refill according to claim 1 , wherein a weight ratio of the polylactide binder to the at least one polymer binder ranges from 0.5 to 10.

10 . The polymer-based lead or refill according to claim 1 , wherein the at least one filler is a mineral filler.

11 . The polymer-based lead or refill according to claim 1 , wherein the at least one filler is a clay.

12 . The polymer-based lead or refill according to claim 1 , wherein the at least one filler is selected from the group consisting of montmorillonite, bentonite, kaolin, and mixtures thereof.

13 . The polymer-based lead or refill according to claim 1 , wherein the at least one filler is kaolin.

14 . The polymer-based lead or refill according to claim 1 , wherein the at least one filler is present in an amount of 15 wt. % to 25 wt. %, based on the total weight of the polymer-based lead or refill.

15 . The polymer-based lead or refill according to claim 1 , wherein the at least one coloring agent is present in an amount of 10 wt. % to 15 wt. %, based on the total weight of the polymer-based lead or refill.

16 . The polymer-based lead or refill according to claim 1 , wherein the at least one slip agent is present in an amount of 10 wt. % to 30 wt. % and/or the at least one wax is present in an amount of 10 wt. % to 30 wt. %, based on the total weight of the polymer-based lead or refill.

17 . The polymer-based lead or refill according to claim 1 , which is a color lead or refill.

18 . A writing, drawing and/or painting tool comprising the polymer-based lead or refill of claim 1 .

19 . The polymer-based lead or refill according to claim 1 , wherein the at least one wax is selected from the group consisting of stearate waxes, calcium stearate, magnesium stearate, zinc stearate, montan waxes, amide waxes, paraffin, and mixtures thereof.

20 . The polymer-based lead or refill according to claim 1 , which has a diameter ranging from 2 mm to 4.5 mm.

21 . The polymer-based lead or refill according to claim 1 , wherein the at least one slip agent is selected from the group consisting of amides, glycerol derivatives, esters of pentaerythritol, and mixtures thereof.