BODY FOR A WRITING, TRACING, DRAWING OR COLORING PENCIL

Abstract

A body for a writing, tracing, drawing or coloring pencil has a composition that includes, by weight, with respect to the total weight of the body between 50% and 95% of a mixture of polylactic acid and of polybutylene succinate in a polylactic acid/polybutylene succinate ratio by weight of between 90/10 and 60/40 and between 5% and 50% of filler that can have shellfish shells and/or calcium carbonate. A writing, tracing, drawing or coloring pencil has such a body.

Claims

1-11. (canceled)

12. A pencil body for a writing, tracing, drawing or coloring pencil, the body having a composition comprising, by weight, with respect to a total weight of the body: between 50% and 95% of a mixture of polylactic acid and polybutylene succinate in a ratio by weight of polylactic acid/polybutylene succinate that is between 90/10 and 60/40 and between 5% and 50% of a filler that is shellfish shells and/or calcium carbonate.

13. The pencil body as claimed in claim 12, wherein the ratio by weight of polylactic acid/polybutylene succinate is between 80/20 and 65/45.

14. The pencil body as claimed in claim 12, wherein the composition comprises, by weight, with respect to the total weight of the body: between 70% and 90% of a mixture of polylactic acid and of polybutylene succinate in a ratio by weight of polylactic acid/polybutylene succinate that is between 80/20 and 65/45 and between 10% and 30% of the filler.

15. The pencil body as claimed in claim 12, wherein the filler is shellfish shells.

16. The pencil body as claimed in claim 12, wherein the filler further comprises ground oyster shells.

17. The pencil body as claimed in claim 12, wherein the shellfish shells have a volume-average diameter (d50) ranging from 10 μm to 160 μm measured by laser particle sizing.

18. The pencil body as claimed in claim 12, wherein the shellfish shells have a volume-average diameter (d50) ranging from 30 μm to 80 μm measured by laser particle sizing.

19. The pencil body as claimed in claim 12, wherein the filler is between 7 and 20%.

20. The pencil body as claimed in claim 12, wherein the filler is between 8 and 20%.

21. The pencil body as claimed in claim 1, wherein the filler is between 10 and 20%.

22. The pencil body as claimed in claim 12, wherein the mixture of polylactic acid/polybutylene succinate is in a ratio between 80/20 and 70/30.

23. The pencil body as claimed in claim 12, wherein the filler does not comprise a crystalline inorganic filler containing more than 10% of SiO.sub.2.

24. The pencil body as claimed in claim 12, wherein the composition further comprises between 0.1% and 10% by weight with respect to the total weight of the body of an adhesion agent.

25. The pencil body as claimed in claim 24, wherein the adhesion agent is polylactic acid grafted by maleic anhydride.

26. The pencil body as claimed in claim 12, wherein the composition further comprises between 0.1% and 10% by weight with respect to the total weight of the body of an additive.

27. The pencil body as claimed in claim 26, wherein the additive is chosen from dyes and/or pigments, blowing agents, processing aids, lubricants, slip agents, modifiers of the performance of the polylactic acid and their mixtures.

28. The pencil body as claimed in claim 12, wherein the pencil body is extrudable.

29. A writing, tracing, drawing or coloring pencil comprising the pencil body as claimed in claim 12.

30. The pencil as claimed in claim 29, wherein the pencil is obtained by extrusion.

31. The pencil as claimed in claim 29, wherein the pencil is a graphite pencil or a colored pencil.

Description

DETAILED DESCRIPTION

[0012] The present disclosure thus relates to a body for a writing, tracing, drawing or coloring pencil, the composition of which comprises (more specifically is essentially composed of, in particular consists of), by weight, with respect to the total weight of the body: [0013] a) between 50% and 95% of a mixture of polylactic acid and of polybutylene succinate in a polylactic acid/polybutylene succinate ratio by weight of between 90/10 and 60/40 and [0014] b) between 5% and 50% of filler.

[0015] In a specific embodiment, its composition comprises (more specifically is essentially composed of, in particular consists of), by weight, with respect to the total weight of the body: [0016] a) between 70% and 90% of a mixture of polylactic acid and of polybutylene succinate in a polylactic acid/polybutylene succinate ratio by weight of between 80/20 and 65/45 and [0017] b) between 10% and 30% of filler.

[0018] The pencil body according to the disclosure thus comprises a mixture of polylactic acid, for example commercially available from Natureplast, and of polybutylene succinate, for example commercially available from Natureplast, in a polylactic acid/polybutylene succinate ratio by weight of between 90/10 and 60/40, in particular between 80/20 and 65/45, more particularly between 80/20 and 70/30, more particularly still in a ratio by weight of 70/30.

[0019] This mixture of biodegradable thermoplastic polymers serves as matrix in the pencil body according to the disclosure and makes it possible to manufacture the pencil body by extrusion and to contribute good mechanical properties, such as impact strength and resilience. It also makes it possible to contribute the ability to be sharpened to the pencil body according to the disclosure.

[0020] The content of mixture of polylactic acid and of polybutylene succinate of the pencil body according to the disclosure is thus between 50% and 95%, more specifically between 60% and 92%, more specifically between 70% and 90%, more specifically still between 80% and 90%, by weight, with respect to the total weight of the body.

[0021] The pencil body according to the present disclosure additionally comprises a filler, which can be inorganic or organic. The filler makes it possible to improve the mechanical properties of the body, such as the (3-point) flexural modulus. More specifically, it is a filler of natural origin; more specifically, the filler can be shellfish shells and/or calcium carbonate, these fillers thus specifically not containing SiO.sub.2; in particular, they are shellfish shells, such as oyster shells or scallop shells, in particular oyster shells, more particularly ground oyster shells, in particular commercially available from Natureplast.

[0022] Shellfish shells are in general composed of calcium carbonate and organic compound(s). Calcium can be replaced in part by other elements such as magnesium, strontium, barium, manganese and mixture thereof.

[0023] The organic compound(s) consist(s) in the following elementary components: C, H, O, N, more specifically the organic compound(s) are proteins and/or carbohydrate.

[0024] The content of filler of the pencil body according to the disclosure is thus between 5% and 50%, more specifically between 8% and 40%, more specifically between 10% and 30%, more specifically still between 10% and 20%, by weight, with respect to the total weight of the body.

[0025] More particularly, in the case where the filler consists of shellfish shells, in particular oyster shells, more specifically ground oyster shells, in particular with a volume-average diameter (d50), measured by laser particle sizing, more specifically ranging from 10 μm to 160 μm, in particular ranging from 20 μm to 100 μm, more specifically from 30 μm to 80 μm, still more particularly of 70 μm with a Mastersizer 3000 type apparatus commercially available from Malvern, its content is specifically between 7% and 20%, more specifically between 8% and 20%, in particular between 10% and 20%, by weight, with respect to the total weight of the body.

[0026] In a particularly advantageous embodiment, the filler consists of shellfish shells, specifically oyster shells or scallop shells, in particular oyster shells, more particularly ground oyster shells, more particularly still with a volume-average diameter (d50), measured by laser particle sizing, more specifically ranging from 10 μm to 160 μm, more specifically ranging from 20 μm to 100 μm, more specifically from 30 μm to 80 μm, still more particularly of 70 μm with a Mastersizer 3000 type apparatus commercially available from Malvern.

[0027] In an advantageous embodiment, the filler has a volume-average diameter (d50), measured by laser particle sizing, more specifically ranging from 10 μm to 160 μm, more specifically ranging from 20 μm to 100 μm, more specifically from 30 μm to 80 μm, still more particularly of 70 μm with a Mastersizer 3000 type apparatus commercially available from Malvern.

[0028] In a specific embodiment, the filler does not comprise a crystalline inorganic filler containing more than 10% of SiO.sub.2, in particular chosen from talc, kaolin, clays and kaolinite, more particularly as described in EPO 821 036.

[0029] In a particular embodiment, the filler does not comprise silicate, i.e. a salt combining silicon dioxide SiO.sub.2 with metal oxides, such as aluminium oxides and/or magnesium oxides.

[0030] More specifically still, the filler does not comprise silicon dioxide SiO.sub.2.

[0031] The pencil body according to the disclosure can additionally comprise an adhesion agent. If the adhesion agent is present, its content is between 0.1% and 10%, in particular between 1% and 6%, more particularly between 2% and 5%, by weight, with respect to the total weight of the body. More specifically, in the case where the filler consists of shellfish shells, in particular oyster shells, the content of adhesion agent is between 0.1 and 5% by weight, with respect to the total weight of the pencil body.

[0032] The adhesion agent makes it possible to improve the adhesion between the thermoplastic polymer (mixture of polylactic acid and of polybutylene succinate) and the filler, in particular when the filler has a high polarity. In particular, the adhesion agent can be polylactic acid grafted by maleic anhydride, for example sold by Natureplast or Natureworks.

[0033] The pencil body according to the present disclosure can comprise other additives, such as, for example, dyes and/or pigments, in particular in the masterbatch form, for example based on PLA, blowing agents, processing aids, lubricants, slip agents, such as stearates (calcium stearate, for example) and/or a stearamide, modifiers of the performance of the PLA (melt enhancers, which improve the strength/consistency of the molten mixture in extrusion), in particular acrylics, and a mixture of these additives. The content of additive of the pencil body according to the present disclosure, when it is present, is between 0.1% and 10% by weight, with respect to the total weight of the body.

[0034] In particular, the pencil body according to the present disclosure comprises a blowing agent, such as, for example, azodicarbonamide, or other endothermic chemical agents, in order to lighten its final weight and to help in its ability to be sharpened, more specifically in a content of between 0.1% and 1%, more specifically in a content of between 0.5% and 1%, by weight, with respect to the total weight of the body.

[0035] The pencil body according to the disclosure can also comprise dyes and/or pigments (such as red iron oxide), in particular in the masterbatch form, more particularly based on PLA. The content of dyes and/or pigments is in particular between 0.1% and 10% by weight, in particular if the dye and/or the pigment is not in the form of a masterbatch, between 0.1% and 5% by weight, more specifically between 0.5% and 3% by weight, with respect to the total weight of the pencil body according to the disclosure. In an advantageous embodiment, the dyes and/or the pigments make it possible to confer a color close to wood on the pencil body according to the disclosure.

[0036] The pencil body according to the present disclosure is more specifically extrudable.

[0037] It can also more specifically be sharpened and can in particular have the density and the ability to be sharpened similar to those of wood. More particularly, it can be sharpened by a conventional pencil sharpener.

[0038] It is thus not the body of a mechanical pencil.

[0039] In addition, the present disclosure relates to a writing, tracing, drawing or coloring pencil comprising the body according to the present disclosure.

[0040] It is not a mechanical pencil.

[0041] More specifically, in the pencil according to the disclosure, the body according to the present disclosure surrounds, in particular concentrically, the lead or an intermediate protective layer positioned between the lead and the body according to the disclosure.

[0042] In particular, the lead is a polymer-based lead and not a calcined lead.

[0043] More specifically, the pencil according to the disclosure is obtained by extrusion, in particular by coextrusion of the lead/optional protective layer/body according to the disclosure.

[0044] More specifically still, it is a graphite pencil or a colored pencil.

[0045] In a specific embodiment of the present disclosure, the pencil according to the disclosure comprises an additional decorative layer, more specifically of varnish, surrounding, in particular concentrically, the body according to the disclosure. More specifically, the decorative layer is made of a material compatible with that of the body according to the disclosure.

[0046] More specifically, the pencil according to the present disclosure can have a hexagonal, round or triangular section, more specifically a round or hexagonal section. More specifically, it can comprise a means for erasing, such as a rubber, at the non-sharpened end of the pencil.

[0047] A better understanding of the disclosure will be obtained on reading the description of the examples which follow.

Examples

[0048] Different compositions (examples 1 to 4 according to the disclosure, mixture of PLA and PBS without filler, polystyrenes of different categories) were tested, before and after extrusion, with regard to their mechanical properties. The flexural modulus of the pencil body has to be greater than or equal to 2000 MPa.

[0049] These compositions are prepared by compounding on a twin-screw extruder which will intimately mix the various ingredients of the formula, the operation being carried out at a temperature of 160° C. to 200° C. A formulated rod is obtained at the twin-screw extruder outlet, which rod is granulated. It is these small granules which are subsequently injection molded in the form of standardized test specimens.

[0050] The tensile tests were carried out according to the standard NF EN ISO 527 of 2012. The bending tests were carried out according to the standard NF EN ISO 178 of 2011 according to the following characteristics:

[0051] Equipment: testing device of 3367 type (Instron)

[0052] Force cell: 1 kN

[0053] Distance between supports: 64 mm

[0054] Test method: A

[0055] Test rate: 2 mm.Math.min.sup.−1

[0056] Sampling: Dumbbell test specimen ISO A

[0057] Number of test specimens tested: 10

[0058] Conditioning: minimum 24 h at 23° C.±2° C. and 50% RH±10% RH

[0059] Test temperature: 23.6° C.

[0060] Test hygrometry: 30%.

[0061] The unnotched Charpy impact tests were carried out according to the standard NF EN ISO 179-1 of 2010 according to the following characteristics:

[0062] Equipment: Impactor II pendulum (Ceast)

[0063] Hammer: 15 J

[0064] Distance of supports: 62 mm

[0065] Sampling: Type 1A test specimen (molded test specimen)

[0066] Positioning: Standing

[0067] Conditioning: minimum 24 h at 23° C.±2° C. and 50% RH±10% RH

[0068] Test temperature: 23.7° C.

[0069] Test hygrometry: 27%

[0070] The viscosity measurements (viscosity index of the material—Melt Flow Index: MFI) were carried out according to the standard NF EN ISO 1133 of 2011, method B, according to the following characteristics:

[0071] Stoving: 18 h at 90° C.

[0072] Equipment: Modular melt flow tester (Ceast)

[0073] Capillary die diameter: 2.095 mm

[0074] Capillary die length: 8 mm

[0075] Test temperature: 190° C.

[0076] Load applied: 2.16 kg

[0077] Time interval: 30 s

[0078] The measurement of the density (MFI) was carried out according to the standard NF EN ISO 1183 of 2012, method A (method by immersion), according to the following characteristics:

[0079] Equipment: ALS/PLS-A01 precision balance (Kern)—density measurement attachments

[0080] Liquid: distilled water

[0081] Test temperature: 23° C.

[0082] Sampling: injected part

[0083] The results are collated in the following tables 1 and 2:

TABLE-US-00001 TABLE 1 Mixture A Mixture B 80% PLA + 70% PLA + Recycled Virgin Virgin Formulation 20% PBS 30% PBS PS HIPS GPPS Performance qualities of the composition before extrusion Flexural modulus (MPa) 2869 2557 1500 1850 2900 Impact strength (kJ/m.sup.2) 32.7 63.8 [8]* [11]* 8 MFI (g/10 min) 12.26 18.29 5 4.5 4 (200° C.-5 kg) MFI (g/10 min) 3.2 3.91 — (190° C.-2.16 kg) Density (g/cm.sup.3) 1.25 1.26 1.04 1.04 1.05 Performance qualities of the extruded rods Resistance to sharpening — — 150 — — (N .Math. mm) Breaking force (daN) — 25.69 11.70 — — Elongation (mm) — 4.86 12.50 — — Diameter (mm) 7.4 7.7 7.3 *these values were produced on notched test specimens (Charpy impact tests) according to the standard NF EN ISO 179-1 of 2010

TABLE-US-00002 TABLE 2 Example 1: Example 2: Example 3: Example 4: 90% Mixture 80% Mixture 90% Mixture 80% Mixture B + B + 10% B + 20% B + 10% ground 20% ground CaCO.sub.3 with CaCO.sub.3 with oyster shells oyster shells a volume- a volume- with a volume- with a volume- average average average average diameter of diameter of diameter of diameter of Formulation 40 μm 40 μm 70 μm 70 μm Performance qualities of the composition before extrusion Flexural 2526.9 2704.6 3029 3551 modulus (MPa) Elongation 2345.6 2176.2 2831.9 3015.6 modulus (MPa) Impact strength 23.7 17.6 (kJ/m.sup.2) MFI (g/10 min) 25.88 >77.3 (200° C.-5 kg) MFI (g/10 min) 5.36 24.84 (190° C.-2.16 kg) Density (g/cm.sup.3) 1.28 1.39 Performance qualities of the extruded rods Resistance to 241 — sharpening (N .Math. mm) Breaking force 22.15 10.80 (daN) Elongation 4.43 3.00 (mm) Diameter (mm) 6.8 6.5

[0084] The results clearly show superior mechanical properties of the examples according to the disclosure in comparison with polystyrene, and even of the filler-free PLA/PBS mixtures in comparison with polystyrene, and also the advantage of using, as filler, oyster shells in comparison with calcium carbonate (the results in elongation and in bending are better for examples 3 and 4 in comparison with examples 1 and 2).

[0085] Pencils of hexagonal section were manufactured by coextrusion with a polypropylene-based graphite lead (composition as % by weight with respect to the total weight of the lead: 26% polypropylene, 8% kaolin, 47% graphite, 9% black pigment coated with polyethylene wax, 8% calcium stearate, 2% additive) or a colored lead based on styrene polymer, a sheath, a body having the composition according to example 3 and a varnish. The thickness of the body is 3.5 mm in the case of the colored leads and 4.5 mm in the case of the graphite leads.

[0086] The pencils obtained are comparable dimensionally and with regard to weight with the conventional pencils having a graphite or colored lead, the body of which is made of polystyrene.

[0087] In addition, the processability with the oyster shells is good.

[0088] The use of oyster shells thus makes it possible to obtain a good resistance of the pencil and a not excessively high sharpening effort.

[0089] Furthermore, no problem is observed with regard to the lead during the operation of sharpening the pencil: the lead does not break and does not become detached from the pencil.

[0090] Different compositions (mixture of PLA and PBS with kaolin as filler (comparative example 2), mixture of PLA alone with, as filler, oyster shells (comparative example 1)) were tested, before extrusion, with regard to their mechanical properties.

[0091] These compositions are prepared by compounding on a twin-screw extruder which will intimately mix the various ingredients of the formula, the operation being carried out at a temperature of 160° C. to 200° C. A formulated rod is obtained at the twin-screw extruder outlet, which rod is granulated. It is these small granules which are subsequently injection molded in the form of standardized test specimens.

[0092] The bending and impact strength tests were carried out using the same protocol as the above examples. The results are collated in table 3 below.

TABLE-US-00003 TABLE 3 Comparative Comparative example 1: example 2: 90% PLA + 10% ground 90% Mixture oyster shells with a B + 10% volume-average diameter Formulation kaolin of 70 μm Performance qualities of the composition before extrusion Flexural 2936 4453 modulus (MPa) Impact 27.5 16.0 strength (kJ/m.sup.2)

[0093] It is noticed that the impact strength of comparative example 1 is less than that of example 3 according to the disclosure and that the flexural modulus of comparative example 1 is less than that of example 3.

[0094] The use of PLA alone or of fillers containing SiO.sub.2, such as kaolin, thus gives poorer results than the PLA/PBS mixture with, as filler, oyster shells.