Crayon comprising calcium silicate

Abstract

In a first aspect, the present disclosure relates to a writing instrument comprising a refill wherein the refill comprises at least about 0.01% by weight of Ca2SiO4 particles relative to the total weight of the refill wherein the Ca2SiO4 has a D50 of between about 5 [mu] m and about 15 [mu] m and a BET value of between about 25 m2 / g and about 55 m2 / g.

Description

[0001] Cross - reference to related applications

[0002] This patent application claims the priority of European Patent Application EP 22306948.5 filed on December 20, 2022, the entire content of which is incorporated herein by reference. Technical field

[0003] The present invention relates to the field of writing instruments. More specifically, the present invention relates to writing instruments containing Ca2SiO4. Background art

[0004] The present invention relates to writing instruments such as crayons or colored pencils.

[0005] Writing instruments (such as pencils and crayons) contain or consist of a solid pigment core, also known as a lead. A writing instrument containing a lead is used to produce a mark by rubbing the lead against a substrate (such as a sheet of paper) to form a deposit on the substrate.

[0006] The lead contains structural components mixed with one or more colorants such as pigments or dyes. For example, a crayon may contain wax as a structural component, where the wax is mixed with a blue pigment to produce a blue crayon.

[0007] However, the resulting color tone of the lead and the mark produced by the lead may be considered too dark. For example, mixing wax with a blue pigment may result in a dark blue lead and its mark. To obtain a lighter - toned lead, wax can be mixed with a white colorant. Typically, due to the strong whitening effect of the white pigment TiO2, this white pigment is used to lighten the color tone of the lead. For example, wax can be mixed with a blue pigment and additional TiO2 to obtain a light blue crayon, which can provide a light blue deposit, especially when deposited on white paper.

[0008] However, there have recently been concerns that TiO2 dust may be carcinogenic to humans. During the production process of a lead containing TiO2, especially during the mixing of the structural components with TiO2, TiO2 dust may be generated, which may be harmful to the manufacturing personnel.

[0009] The present disclosure aims to solve the aforementioned problems in optimizing the composition of the lead of a writing instrument. Summary of the invention

[0010] In a first aspect, the present disclosure relates to a writing instrument including a lead, wherein the lead contains at least about 0.01 wt% of Ca2SiO4 particles relative to the total weight of the lead, wherein the Ca2SiO4 has a D between about 5 μm and about 15 μm 50 and between about 25m 2from about 55 m / g to 2 BET value between

[0011] In some embodiments, the Ca2SiO4 particles can have a D between about 3 μm and about 150 μm, more specifically between about 7 μm and about 50 μm, and particularly between 10 μm and about 30 μm 90 .

[0012] In some embodiments, the refill may contain less than about 1 wt%, more specifically less than about 0.5 wt%, more specifically less than about 0.2 wt% of TiO2, and particularly be substantially free or free of TiO2.

[0013] In some embodiments, the refill may contain less than about 0.5 wt%, more specifically less than about 0.2 wt% of FeS, and particularly be substantially free or free of FeS.

[0014] In some embodiments, the refill may contain at least one additional pigment from the group of BaSO4, CaCO3, ZnS, ZnO, and ZrO2, and particularly the refill may contain all the pigments BaSO4, CaCO3, and ZnS.

[0015] In some embodiments, the ratio of BaSO4 to Ca2SiO4 may be between about 8:1 and about 1:1, more specifically between about 6:1 and about 1.5:1, and particularly between about 4:1 and about 2:1.

[0016] In some embodiments, the ratio of BaSO4 to CaCO3 may be between about 50:1 and about 2:1, more specifically between about 30:1 and about 5:1, and particularly between about 20:1 and about 7:1.

[0017] In some embodiments, the ratio of BaSO4 to the total content of ZnS, ZnO, and ZrO2 may be between about 5:1 and about 1:3, more specifically between about 3:1 and about 1:2, and particularly between about 2:1 and about 1:1.

[0018] In some embodiments, the ratio of Ca2SiO4 to CaCO3 may be between about 8:1 and about 1:1, more specifically between about 6:1 and about 1.5:1, and particularly between about 4:1 and about 2:1.

[0019] In some embodiments, the ratio of the total content of ZnS, ZnO, and ZrO2 to Ca2SiO4 may be between about 5:1 and about 1:3, more specifically between about 4:1 and about 1:2, and particularly between about 3:1 and about 1:1.

[0020] In some embodiments, the ratio of the total content of ZnS, ZnO, and ZrO2 to CaCO3 can be between about 20:1 and about 1:1, more specifically between about 15:1 and about 2:1, and particularly between about 10:1 and about 3:1

[0021] In some embodiments, the BaSO4 particles can have a D between about 0.1 μm and about 10 μm, more specifically between about 0.3 μm and about 3 μm, and particularly between about 0.5 μm and about 1.5 μm 50 。

[0022] In some embodiments, the CaCO3 particles can have a D between about 10 nm and about 1000 nm, more specifically between about 30 nm and about 300 nm, and particularly between about 50 nm and about 150 nm 50 。

[0023] In some embodiments, the ZnS, ZnO, and / or ZrO2 particles can have a D between about 30 nm and about 1000 nm, more specifically between about 50 nm and about 700 nm, and particularly between about 250 nm and about 450 nm 50 。

[0024] In some embodiments, the BaSO4 particles can have a D between about 0.15 μm and about 15 μm, more specifically between about 0.5 μm and about 5 μm, and particularly between about 1.3 μm and about 2.3 μm 90 。

[0025] In some embodiments, the CaCO3 particles can have a D between about 50 nm and about 1500 nm, more specifically between about 150 nm and about 700 nm, and particularly between about 250 nm and about 400 nm 90 。

[0026] In some embodiments, the ZnS, ZnO, and / or ZrO2 particles can have a D between about 50 nm and about 1500 nm, more specifically between about 300 nm and about 1250 nm, and particularly between about 700 nm and about 1000 nm 90 。

[0027] In some embodiments, the BaSO4 particles can have a BET surface area, measured according to DIN ISO 9277:2014-01, between about 0.5 m 2 / g and about 20 m 2 / g, more specifically between about 1.5 m 2 / g and about 8 m 2between about 5 m² / g and, in particular, about 2 m² / g 2 / g to about 6 m² / g 2 BET value of m² / g.

[0028] In some embodiments, the CaCO₃ particles can have a BET value measured according to DIN ISO 9277:2014-01 between about 5 m² 2 / g to about 150 m² 2 / g, more specifically between about 10 m² 2 / g to about 70 m² 2 / g, and in particular about 20 m² 2 / g to about 40 m² 2 / g BET value.

[0029] In some embodiments, the ZnS, ZnO, and / or ZrO₂ particles can have a BET value measured according to DIN ISO 9277:2014-01 between about 1 m² 2 / g to about 20 m² 2 / g, more specifically between about 3 m² 2 / g to about 15 m² 2 / g, and in particular about 5 m² 2 / g to about 11 m² 2 / g BET value.

[0030] In some embodiments, the refill can contain between about 0.1 wt% and about 24 wt%, more specifically between about 0.5 wt% and about 18 wt%, and in particular between about 1.0 wt% and about 12 wt% of Ca₂SiO₄, relative to the total weight of the refill.

[0031] In some embodiments, the writing instrument can be a handheld writing instrument.

[0032] In some embodiments, the refill can have a diameter between about 5 mm and about 35 mm, more specifically between about 6 mm and about 20 mm, and in particular between 7 mm and about 12 mm.

[0033] In some embodiments, the writing instrument can include a housing, and the refill can be included within the housing.

[0034] In some embodiments, the refill can have a diameter between about 2.0 mm and about 4.5 mm, more specifically between about 2.3 mm and about 4.2 mm, and in particular between about 2.8 mm and about 4.0 mm.

[0035] In some embodiments, the refill can contain one or more waxes between about 10 wt% and about 95 wt% relative to the total weight of the refill.

[0036] In some embodiments, the refill may comprise one or more waxes in an amount between about 50 wt% and about 95 wt%, more specifically between about 60 wt% and about 90 wt%, and particularly between about 70 wt% and about 85 wt% based on the total weight of the refill.

[0037] In some embodiments, the refill may comprise one or more waxes in an amount between about 10 wt% and about 45 wt%, more specifically between about 15 wt% and about 40 wt%, and particularly between about 20 wt% and about 30 wt% based on the total weight of the refill.

[0038] In some embodiments, the refill may comprise a polymer, more specifically a thermoplastic, even more specifically an olefin, and particularly polyethylene or polypropylene, in an amount between about 10 wt% and about 45 wt%, more specifically between about 15 wt% and about 35 wt%, and particularly between about 18.5 wt% and about 27 wt% based on the total weight of the refill.

[0039] In some embodiments, the refill may comprise a fatty acid or its salt in an amount between about 1 wt% and about 20 wt%, more specifically between about 3 wt% and about 17 wt%, and particularly between about 5 wt% and about 15 wt% based on the total weight of the refill.

[0040] In some embodiments, the refill may comprise a fatty acid salt, wherein the fatty acid or salt may comprise a monovalent straight-chain or branched-chain saturated or unsaturated carboxylate having between about 8 and about 24 carbon atoms, more specifically a monovalent straight-chain saturated carboxylate having between about 16 and about 20 carbon atoms, and particularly stearic acid, calcium stearate, zinc stearate, or a mixture thereof.

[0041] In some embodiments, the refill may comprise a filler, particularly hydrated aluminosilicate and / or alkali metal carbonate and / or alkaline earth metal carbonate.

[0042] In some embodiments, the refill may comprise a filler in an amount between about 10 wt% and about 50 wt%, more specifically between about 17 wt% and about 40 wt%, and particularly between about 23.5 wt% and about 32 wt% based on the total weight of the refill.

[0043] In some embodiments, the refill may comprise hydrated aluminosilicate, more specifically layered hydrated aluminosilicate, and particularly kaolinite, in an amount between about 5 wt% and about 30 wt%, more specifically between about 10 wt% and about 25 wt%, and particularly between about 15 wt% and about 20 wt% based on the total weight of the refill.

[0044] In some embodiments, the refill may comprise an alkali metal carbonate and / or an alkaline earth metal carbonate, more specifically an alkaline earth metal carbonate, in an amount between about 5 wt% and about 20 wt%, more specifically between about 7 wt% and about 15 wt%, and particularly between about 8.5 wt% and about 12 wt%, based on the total weight of the refill.

[0045] In some embodiments, the refill may comprise a processing aid, more specifically a lubricant, and particularly pentaerythritol tetrastearate, in an amount between about 2 wt% and about 20 wt%, more specifically between about 4 wt% and about 15 wt%, and particularly between about 7 wt% and about 11 wt%, based on the total weight of the refill.

[0046] In some embodiments, the refill may comprise a plasticizer, more specifically a phthalate, and particularly an alkyl benzyl phthalate C7-C9, in an amount between about 0.5 wt% and about 5 wt%, more specifically between about 1 wt% and about 3.5 wt%, and particularly between about 1.5 wt% and about 2.5 wt%, based on the total weight of the refill.

[0047] In some embodiments, the refill may comprise one or more colorants in an amount between about 0.05 wt% and about 10 wt%, more specifically between about 0.05 wt% and about 7 wt%, and particularly between about 0.1 wt% and about 5 wt%, based on the total weight of the refill.

[0048] In some embodiments, the refill may comprise a hydrated aluminosilicate, more specifically a layered hydrated aluminosilicate, and particularly kaolinite, in an amount between about 5 wt% and about 80 wt%, more specifically between about 10 wt% and about 60 wt%, even more specifically between about 15 wt% and about 55 wt%, and particularly between about 15 wt% and about 50 wt%, based on the total weight of the refill. Detailed Description

[0049] Hereinafter, a detailed description of the present disclosure will be given. The terms or words used in the description and aspects of the present disclosure should not be construed restrictively as having only a common language or dictionary meaning, and should be interpreted as having their ordinary technical meaning as determined in the relevant technical field, unless otherwise explicitly defined in the following description. The detailed description will better illustrate the present disclosure with reference to specific examples, but it should be understood that the disclosed content is not limited to these specific embodiments.

[0050] Writing instruments, such as pens or crayons, include or consist of a solid pigment core, also known as a refill. The writing instrument containing the refill is used to produce a mark by rubbing the refill against a substrate, such as a sheet of paper. To adjust the brightness of the refill and its deposit, TiO2 is commonly used as an effective whitening pigment.

[0051] However, concerns have recently emerged that TiO2 dust may be carcinogenic to humans. During the production process of refills containing TiO2, particularly during the mixing of the structural components with TiO2, TiO2 dust may be generated, which can be harmful to the manufacturing personnel. Additionally, in some jurisdictions, TiO2 in powder form has been prohibited from being used above a certain concentration due to concerns about the carcinogenic risk of inhalation. For example, the European Union (EU) has restricted the use of TiO2 powder to 1 wt%, or the product must be labeled as containing a possible carcinogen, even if TiO2 cannot be airborne from the product. Therefore, an alternative to TiO2 for adjusting the brightness of the refill is needed.

[0052] However, replacing TiO2 with other white colorants, especially pigments, is not straightforward because white colorants are not interchangeable. An alternative white colorant may not be equally effective in improving the brightness of the refill and / or the deposit of the refill. Additionally, an alternative white colorant may cause decolorization of the refill and / or the deposit of the refill, especially a slightly yellowish color. Worse still, TiO2 is an almost ideal white colorant because it is effective in providing a refill where the color of the refill is considered to be very similar to the deposit formed. This can make it easier for the user to choose between different colors and predict how the mark will look. An alternative white colorant may produce a refill where the perceived color of the refill is strongly different from the deposit of the refill.

[0053] An alternative pigment that can be used to replace TiO2 is zirconia, ZrO2. However, the production of ZrO2 can be energy-intensive and expensive. A large number of additional pigments have been tried to replace TiO2, but have shown unsatisfactory results.

[0054] Surprisingly, it has been found that calcium silicate, Ca2SiO4, which exhibits a high BET value relative to its particle size, can be an effective white pigment for increasing the brightness of the refill. Additionally, the Ca2SiO4 pigment may not cause significant decolorization, such as a slightly yellowish color.

[0055] Accordingly, in a first aspect, the present disclosure relates to a writing instrument including a refill, wherein the refill contains at least about 0.01 wt% of Ca2SiO4 particles relative to the total weight of the refill, wherein the Ca2SiO4 particles have a D between about 5 μm and about 15 μm 50and between about 25 m 2 / g to about 55 m 2 / g. The BET value can be measured according to DIN ISO 9277:2014-01.

[0056] Without being bound by theory, it is believed that the high BET value of Ca2SiO4, compared to its particle size distribution, can lead to an improved degree of whiteness of Ca2SiO4.

[0057] Similarly, without being bound by theory, white pigments typically act by scattering light of all wavelengths, especially due to their relatively high refractive index. Local inhomogeneous factors on the particle surface can cause scattering. Therefore, it is believed that theoretically perfect spherical particles may result in a lower degree of scattering compared to particles containing the aforementioned inhomogeneous factors. Perfect spheres exhibit the smallest ratio of particle size to surface area, and thus their BET value is also the smallest. Therefore, a higher BET value indicates a higher amount of inhomogeneous factors (especially reflective surfaces) contained within the particles relative to the mass of the particles.

[0058] Furthermore, still without being bound by theory, it is believed that Ca2SiO4 particles exhibiting a high BET value can be effective white pigments in the cores of writing instruments because the particles may not be effectively wetted by the matrix surrounding them, especially due to their nested geometry. The effect of light scattering depends on the difference between the refractive index of the matrix and the refractive index of the pigment disposed therein. For example, in a crayon, the matrix can contain wax (such as paraffin wax), which can exhibit a refractive index of about 1.55, while Ca2SiO4 can exhibit a refractive index of about 1.7. Therefore, in a paraffin wax matrix, Ca2SiO4 pigment particles may not be able to refract light effectively. However, the refractive index of air is about 1.00. Therefore, if the surface of the Ca2SiO4 pigment particles is not completely wetted by the paraffin wax matrix, the incident light can be refracted at the air-particle interface, which can result in a much more effective refraction compared to the paraffin-particle interface and thus can produce a more effective pigment.

[0059] It should be understood that calcium silicate (Ca2SiO4) encompasses hydrated calcium silicate as well as non-hydrated calcium silicate.

[0060] In some embodiments, Ca2SiO4, more specifically hydrated Ca2SiO4, can have a crystalline structure, i.e., Ca2SiO4 can be crystalline. More specifically, in some embodiments, the crystal form of Ca2SiO4, more specifically the crystal form of hydrated Ca2SiO4, can be monoclinic, more specifically monoclinic-prismatic.

[0061] In some embodiments, Ca2SiO4 is advantageously hydrated.

[0062] Ca2SiO4 may be present in an amount of Ca2SiO4 that is between about 0.1 wt% and about 24 wt%, more specifically between about 0.5 wt% and about 18 wt%, and particularly between about 1.0 wt% and about 12 wt% relative to the total weight of the refill. The amount of Ca2SiO4 can be adjusted according to the desired hue of the refill.

[0063] In some embodiments, the refill may contain less than about 1 wt%, more specifically less than about 0.5 wt%, more specifically less than about 0.2 wt% of TiO2, and particularly be substantially free or free of TiO2. Thus, Ca2SiO4 can be used to replace TiO2.

[0064] Iron sulfide, FeS, may be present in some pigments, particularly white pigments. However, small amounts of FeS impurities may cause the white pigment to be slightly yellow or gradually turn slightly gray. Thus, the refill may contain less than about 0.5 wt%, more specifically less than about 0.2 wt% of FeS, and particularly be substantially free or free of FeS.

[0065] The writing instrument can be a hand-held writing instrument.

[0066] The degree of brightening provided by Ca2SiO4 can be improved by including additional pigments. Thus, in some embodiments, the refill may contain at least one additional pigment from the group of BaSO4, CaCO3, ZnS, ZnO, and ZrO2, and particularly the refill may contain all of the pigments BaSO4, CaCO3, and ZnS.

[0067] It has been found that improved brightening may be observable when the ratio of BaSO4 to Ca2SiO4 can be between about 8:1 to about 1:1, more specifically between about 6:1 to about 1.5:1, and particularly between about 4:1 to about 2:1. In addition, the ratio of BaSO4 to CaCO3 can be between about 50:1 to about 2:1, more specifically between about 30:1 to about 5:1, and particularly between about 20:1 to about 7:1. Additionally, the ratio of BaSO4 to the total content of ZnS, ZnO, and ZrO2 can be between about 5:1 to about 1:3, more specifically between about 3:1 to about 1:2, and particularly between about 2:1 to about 1:1. The ratio of Ca2SiO4 to CaCO3 can be between about 8:1 to about 1:1, more specifically between about 6:1 to about 1.5:1, and particularly between about 4:1 to about 2:1. The ratio of the total content of ZnS, ZnO, and ZrO2 to Ca2SiO4 can be between about 5:1 to about 1:3, more specifically between about 4:1 to about 1:2, and particularly between about 3:1 to about 1:1. Finally, the ratio of the total content of ZnS, ZnO, and ZrO2 to CaCO3 can be between about 20:1 to about 1:1, more specifically between about 15:1 to about 2:1, and particularly between about 10:1 to about 3:1. The above ratios are weight ratios.

[0068] Generally speaking, the brightness and color of the refill can be defined according to the CIELAB or CIELCh color space. The CIELAB color space (also known as L*a*b*) is a color space defined by the International Commission on Illumination. The color space is designed to approximate human vision. The CIELAB color space defines colors according to three coordinates L * , a*, and b*. L* represents the brightness of the color. L * = 0 produces black, and L * = 100 represents diffused white. Specular white can reach an L * value higher than 100. A * defines the color position between red and green. A negative a * value represents green, while a positive value represents red. B * defines the color position between blue and yellow. A negative b * value represents blue, while a positive value represents yellow.

[0069] The CIELCh color space is based on the CIELAB color space. In the CIELCh color space, the brightness L *Remain unchanged. However, a* and b* are converted into polar coordinates C* for chroma / relative saturation and an angle h° for hue angle / hue in the CIELAB color wheel. The term "chroma" within the present disclosure is well known in the art and is given its common meaning within the relevant technical field. In some embodiments, the term "chroma" may refer to the chromaticity of a region judged to be in proportion to the luminance of a similarly illuminated region that appears white or highly transmissive.

[0070] C* can be derived from a* and b* by Equation I:

[0071]

[0072] h° can be derived from a* and b* by Equation II:

[0073]

[0074] In addition, based on the L * , a*, and b* values, the color difference can be calculated based on ISO / CIE 11664-6:2014 - Colorimetry, Part 6: CIEDE2000 Color Difference Formula. ISO / CIE 11664-6:2014 - Colorimetry, Part 6: CIEDE2000 Color Difference Formula, particularly the color difference formula, is incorporated herein by reference.

[0075] A protocol for measuring the L * , a * and b * values is provided in the experimental section.

[0076] D 50 is a measure for particle size, particularly the mass median diameter and thus the median particle size by volume. In particular, it has been found that the following particle sizes can improve the lighting effect of additional pigments. BaSO4 particles can have a D 50 ranging from about 0.1 μm to about 10 μm, more specifically from about 0.3 μm to about 3 μm, particularly from about 0.5 μm to about 1.5 μm. Additionally, CaCO3 particles can have a D 50Finally, the ZnS, ZnO, and / or ZrO2 particles can have a D that is between about 30 nm and about 1000 nm, more specifically between about 50 nm and about 700 nm, and particularly between about 250 nm and about 450 nm. 50 .

[0077] Without being bound by theory, it is believed that when present, the small particle size of CaCO3 can cause the aforementioned effects. In particular, the CaCO3 particles can act as a "spacer" between the particles of Ca2SiO4 and the optional BaSO4, ZnS, ZnO, and / or ZrO2 particles. CaCO3 can increase the space between the individual particles of Ca2SiO4 and the optional BaSO4, ZnS, ZnO, and / or ZrO2 particles, which can increase the brightening effect of each particle, which in turn can increase the overall brightness of the refill at the same pigment amount. Additionally, CaCO3 can result in a more uniform distribution of the particles of Ca2SiO4 and the optional BaSO4, ZnS, ZnO, and / or ZrO2 particles, which in turn can also increase the overall brightness of the refill at the same pigment amount. Without being bound by theory, it is believed that the CaCO3 particles can be arranged around the particles of at least one pigment while only covering a small portion of the total surface area of the pigment. Thus, the CaCO3 particles can extend from the surface of the particles of at least one pigment, thereby increasing the distance between the particles of at least one pigment. Therefore, the probability that light strikes the particles of at least one pigment can increase in the presence of small CaCO3 particles compared to the amount of at least one pigment without CaCO3 particles.

[0078] Another measure for particle size is D 90 , specifically 90 volume% of the particles exhibit a diameter less than D 90 . In particular, D 90 can be used together with D 50 to estimate the width of the particle size distribution. The particle size distribution, as well as D 50 and D 90 can be measured, for example, according to ISO 13320:2020. The BaSO4 particles can have a D that is between about 0.15 μm and about 15 μm, more specifically between about 0.5 μm and about 5 μm, and particularly between about 1.3 μm and about 2.3 μm. 90 . The Ca2SiO4 particles can have a D that is between about 3 μm and about 150 μm, more specifically between about 7 μm and about 50 μm, and particularly between 10 μm and about 30 μm. 90 . The CaCO3 particles can have a D that is between about 50 nm and about 1500 nm, more specifically between about 150 nm and about 700 nm, and particularly between about 250 nm and about 400 nm. 90。ZnS, ZnO, and ZrO2 particles may have a D between about 50 nm and about 1500 nm, more specifically between about 300 nm and about 1250 nm, and particularly between about 700 nm and about 1000 nm 90 。

[0079] In addition, it has been found that the BET values of other pigments may also affect the degree of brightening provided by the pigments. The BET value is a measure of the specific surface area of the material. BaSO4 particles may have a BET value between about 0.5 m 2 / g and about 20 m 2 / g, more specifically between about 1.5 m 2 / g and about 8 m 2 / g, and particularly about 2 m 2 / g and about 6 m 2 / g, measured according to DIN ISO 9277:2014-01. In addition, CaCO3 particles may have a BET value between about 5 m 2 / g and about 150 m 2 / g, more specifically between about 10 m 2 / g and about 70 m 2 / g, and particularly about 20 m 2 / g and about 40 m 2 / g, measured according to DIN ISO 9277:2014-01. Finally, ZnS, ZnO, and / or ZrO2 particles may have a BET value between about 1 m 2 / g and about 20 m 2 / g, more specifically between about 3 m 2 / g and about 15 m 2 / g, and particularly about 5 m 2 / g and about 11 m 2 / g, measured according to DIN ISO 9277:2014-01.

[0080] In some embodiments, the writing instrument can be a crayon.

[0081] In some embodiments, particularly where the writing instrument is a crayon, the core may have a diameter between about 5 mm and about 35 mm, more specifically between about 6 mm and about 20 mm, and particularly 7 mm and about 12 mm.

[0082] In some embodiments, particularly where the writing instrument is a crayon, the core may comprise one or more waxes in an amount between about 10 wt% and about 95 wt% relative to the total weight of the core.

[0083] In some embodiments, particularly where the writing instrument is a crayon, the core may comprise one or more waxes in an amount between about 50 wt% and about 95 wt%, more specifically between about 60 wt% and about 90 wt%, and particularly between about 70 wt% and about 85 wt% relative to the total weight of the core.

[0084] In some additional alternative embodiments, particularly where the writing instrument is a crayon, the core may comprise one or more waxes in an amount between about 10 wt% and about 45 wt%, more specifically between about 15 wt% and about 40 wt%, and particularly between about 20 wt% and about 30 wt% relative to the total weight of the core.

[0085] The term "wax" in the present disclosure is intended to be used as is recognized in the field of writing instruments, and particularly, means a lipophilic (fatty) compound that is solid at, for example, room temperature (e.g., about 25 °C), and that has a reversible solid / liquid state change. The method for measuring the melting point of the wax is not particularly limited, and a differential scanning calorimeter (DSC), such as the calorimeter sold by Mettler Toledo under the name DSC 3, can be used to measure it.

[0086] Among the foregoing waxes, the present disclosure relates to waxes having a melting point of at least about 40 °C and a water solubility of less than about 1000 mg / L at about 25 °C. These properties can contribute to providing a relatively water-insoluble solid base matrix for a writing instrument, particularly for a crayon, in which pigments are dispersed. In some embodiments, one or more waxes may have a melting point of at least about 35 °C, more specifically at least about 50 °C, and particularly at least about 75 °C. In some embodiments, the wax may have a melting point range between about 35 °C and about 200 °C, more specifically between about 55 °C and about 180 °C, and particularly between about 75 °C and about 150 °C.

[0087] In some embodiments, the wax may have a water solubility of less than about 100 mg / L at about 25 °C, more specifically a solubility of less than about 10 mg / L, and particularly a solubility of less than about 1 mg / L. In some embodiments, the wax may be substantially insoluble or insoluble in water at about 25 °C. The method for determining the solubility of the wax is not particularly limited, and it can be carried out in any suitable manner, such as using USP dissolution apparatus 2 (paddle).

[0088] In some embodiments, one or more waxes may include one or more nonpolar waxes. Examples of such nonpolar waxes include paraffin wax, microcrystalline wax, ozokerite, and Fischer-Tropsch wax. The nonpolar waxes may be hydrocarbon-based and may be substantially free or free of polar groups.

[0089] In some embodiments, particularly where the writing instrument is a crayon, the core may comprise a polymer, more particularly a thermoplastic, even more particularly an olefin, and especially polyethylene or polypropylene, in an amount between about 10 wt% and about 45 wt%, more specifically between about 15 wt% and about 35 wt%, and particularly between about 18.5 wt% and about 27 wt% relative to the total weight of the core. The polymer may increase the fracture resistance of the core. The addition of the polymer may increase the elastic modulus and / or hardness of the core.

[0090] In some embodiments, particularly where the writing instrument is a crayon, the core may comprise a fatty acid or its salt in an amount between about 1 wt% and about 20 wt%, more specifically between about 3 wt% and about 17 wt%, and particularly between about 5 wt% and about 15 wt% relative to the total weight of the core.

[0091] In some embodiments, particularly where the writing instrument is a crayon, the fatty acid or salt may comprise a monovalent straight-chain or branched-chain saturated or unsaturated carboxylate having between about 8 and about 24 carbon atoms, more specifically a monovalent straight-chain saturated carboxylate having between about 16 and about 20 carbon atoms, and particularly stearic acid, calcium stearate, zinc stearate, or a mixture thereof. The fatty acid and / or fatty acid salt may improve the smoothness of writing and / or drawing, particularly by improving slip. In addition, the fatty acid and / or fatty acid salt may increase deposition and thereby improve the quality of the deposit. The fatty acid may migrate to the surface of the core, which may result in the formation of a fatty film, which may be displeasing to the user. In some cases, the fatty acid salt may be advantageous because they have a reduced tendency to migrate to the surface of the core.

[0092] In some embodiments, particularly where the writing instrument is a crayon, the core may comprise a filler. The filler may be, for example, hydrated aluminosilicate and / or alkali metal carbonate and / or alkaline earth metal carbonate.

[0093] In some embodiments, particularly where the writing instrument is a crayon, the core may comprise a filler in an amount between about 10 wt% and about 50 wt%, more specifically between about 17 wt% and about 40 wt%, and particularly between about 23.5 wt% and about 32 wt% relative to the total weight of the core. Some fillers, particularly kaolinite, may comprise a layered structure. Thus, fillers such as kaolinite may improve the deposition of the core by providing surfaces along which shearing may occur. Additionally, the filler may reduce the cost of the core.

[0094] In some embodiments, particularly where the writing instrument is a crayon, the core may comprise between about 5 wt% and about 30 wt%, more specifically between about 10 wt% and about 25 wt%, and particularly between about 15 wt% and about 20 wt% of a hydrated aluminosilicate, more specifically a layered hydrated aluminosilicate, and particularly kaolinite, based on the total weight of the core. In some embodiments, the hydrated aluminosilicate may be at least partially or fully replaced by mica and / or talc.

[0095] In some embodiments, particularly where the writing instrument is a crayon, the core may comprise between about 5 wt% and about 20 wt%, more specifically between about 7 wt% and about 15 wt%, and particularly between about 8.5 wt% and about 12 wt% of an alkali metal carbonate and / or an alkaline earth metal carbonate, more specifically an alkaline earth metal carbonate, based on the total weight of the core.

[0096] In some embodiments, particularly where the writing instrument is a crayon, the core may comprise between about 0.5 wt% and about 5 wt%, more specifically between about 1 wt% and about 3.5 wt%, and particularly between about 1.5 wt% and about 2.5 wt% of a plasticizer, more specifically a phthalate, and particularly an alkyl benzyl phthalate C7-C9. The plasticizer may soften the core and thereby increase the deposition of the core, which in turn may improve the visibility and / or strength of the deposit.

[0097] In some embodiments, particularly where the writing instrument is a crayon, the core may comprise between about 2 wt% and about 20 wt%, more specifically between about 4 wt% and about 15 wt%, and particularly between about 7 wt% and about 11 wt% of a processing aid, more specifically a lubricant, and particularly pentaerythritol tetrastearate. The processing aid may improve the manufacturing efficiency of the core.

[0098] In some embodiments, particularly where the writing instrument is a crayon, the core may include one or more colorants in an amount between about 0.05 wt% and about 10 wt%, more specifically between about 0.05 wt% and about 7 wt%, and particularly between about 0.1 wt% and about 5 wt% based on the total weight of the core. The one or more colorants (such as dyes or pigments (i.e., additional pigments other than ZrO2, ZnS, ZnO, BaSO4, CaCO3, Ca2SiO4 or TiO2)) can adjust the color of the core. For example, the addition of a blue pigment can produce a blue core. The term "colorant" as used within this disclosure is well known in the art. In this disclosure, the proportion attributable to the colorant "shall not apply to ZrO2, ZnS, ZnO, BaSO4, CaCO3, Ca2SiO4 or TiO2. In other words, for the purposes of this disclosure, the term "colorant" does not include ZrO2, ZnS, ZnO, BaSO4, CaCO3, Ca2SiO4 or TiO2.

[0099] In some embodiments, particularly where the writing instrument is a pen agent, the writing instrument may include a housing, and the core may be included within the housing.

[0100] In some embodiments, particularly where the writing instrument is a pen agent, the core may have a diameter between about 2.0 mm and about 4.5 mm, more specifically between about 2.3 mm and about 4.2 mm, and particularly between about 2.8 mm and about 4.0 mm.

[0101] In some embodiments, particularly where the writing instrument is a pen agent, the core may include between about 5 wt% and about 80 wt%, more specifically between about 10 wt% and about 60 wt%, even more specifically between about 15 wt% and about 55 wt%, and particularly between about 15 wt% and about 50 wt% of hydrated aluminosilicate, more specifically layered hydrated aluminosilicate, and particularly kaolinite, based on the total weight of the core. In some embodiments, the hydrated aluminosilicate may be at least partially or completely replaced by mica and / or talc.

[0102] In some embodiments, particularly where the writing instrument is a pen agent, the core may include between about 1 wt% and about 20 wt%, more specifically between about 3 wt% and about 17 wt%, and particularly between about 5 wt% and about 15 wt% of a fatty acid or its salt, based on the total weight of the core.

[0103] In some embodiments, particularly where the writing instrument is a pen agent, the fatty acid or salt may comprise a monovalent straight-chain or branched-chain saturated or unsaturated carboxylate having between about 8 and about 24 carbon atoms, more specifically a monovalent straight-chain saturated carboxylate having between about 16 and about 20 carbon atoms, and particularly stearic acid, calcium stearate, zinc stearate, or a mixture thereof.

[0104] In some embodiments, particularly where the writing instrument is a pen agent, the pen core may comprise one or more colorants in an amount between about 5 wt% and about 30 wt%, more specifically between about 10 wt% and about 25 wt%, and particularly between about 13 wt% and about 17 wt% based on the total weight of the pen core.

[0105] In some embodiments, particularly where the writing instrument is a pen agent, the pen core may comprise a binder in an amount between about 3 wt% and about 50 wt%, more specifically between about 10 wt% and about 50 wt%, even more specifically between about 15 wt% and about 45 wt%, and particularly between about 20 wt% and about 40 wt% based on the total weight of the pen core, more specifically a polymeric binder, and particularly a styrenic polymer such as polystyrene and / or acrylonitrile butadiene styrene.

[0106] In some embodiments, particularly where the writing instrument is a pen agent, the pen core may comprise a plasticizer in an amount between about 0.5 wt% and about 10 wt%, more specifically between about 2 wt% and about 8 wt%, and particularly between about 3.5 wt% and about 6.5 wt% based on the total weight of the pen core, more specifically a benzoate.

[0107] Experimental Section

[0108] The so-called "white pigment blend" hereinafter means a combination of BaSO4, CaCO3, and ZnS.

[0109] Experiments were conducted to determine the effect of the composition (white pigment blend) according to the first aspect on the colorimetric values. The results were also compared with TiO2 and ZrO2 compositions. Crayon compositions were used for the tests. The compositions are provided in Table 1.

[0110] Manufacture of Specimens :

[0111] The following steps were carried out to manufacture specimens having the compositions according to Table 1:

[0112] 1) Mix all components.

[0113] 2) Set the thermostatic bath (e.g., AMETEK Brookfield TC-202) to a temperature of 150 °C and add the mixing container to the thermostatic bath.

[0114] 3) Add the mixture to the mixing container in the thermostatic bath.

[0115] 4) Stir the mixture of neutral base and colorant for 2 hours at 2000 rpm using the butterfly tool attached to the DISPERMAT CV3 Plus of VMA-Getzmann GmbH.

[0116] 5) Remove the butterfly tool and fill the molten mixture into a cubic mold with dimensions of 25 mm × 100 mm ×

[0117] 10 mm.

[0118] 6) Cool the mixture and then remove the completed sample from the mold.

[0119] Table 1 shows the composition of the specimens.

[0120] Table 1 - Exemplary Compositions of Specimens for Testing

[0121]

[0122]

[0123] Colorimetry on Crayon Surfaces - Test Setup :

[0124] To measure the colorimetric data in the CIE L*a*b* color space, such as L * , a * and b * , a KONICA MINOLTA CM-3610A spectrophotometer was used. The following settings were applied to the KONICA MINOLTA CM-3610A spectrophotometer:

[0125] Illuminant: D65,

[0126] Angle: 10°,

[0127] Mirror component: Included.

[0128] The spectrophotometer was used with a measurement aperture of 25.4 mm. For the colorimetric measurement of the surface of the crayon, the surface of the crayon was placed in direct contact with the lens of the spectrophotometer.

[0129] Test Results

[0130] Table 2 Results of Colorimetric Tests for Example A and Comparative Composition A .

[0131]

[0132] Table 3 Results of Colorimetric Tests for Example B and Comparative Composition B 。

[0133]

[0134] As can be seen from the results, Ca2SiO4 having a D between about 5 μm and about 15 μm 50 and a BET value between about 25 m 2 / g and about 55 m 2 / g allows for the provision of a refill with improved brightness. In particular, as can be seen from Tables 2 and 3, the presence of such Ca2SiO4 provides an improved L* value compared to ZrO2.

[0135] The present disclosure also relates to the following embodiments.

[0136] Embodiments

[0137] 1. A writing instrument, the writing instrument comprising a refill, wherein the refill comprises:

[0138] at least about 0.01% by weight of Ca2SiO4 particles relative to the total weight of the refill,

[0139] wherein the Ca2SiO4 particles have a D between about 5 μm and about 15 μm 50 , and

[0140] a BET value between about 25 m 2 / g and about 55 m 2 / g.

[0141] 2. The writing instrument according to embodiment 1, wherein the Ca2SiO4 particles have a D between about 3 μm and about 150 μm, more specifically between about 7 μm and about 50 μm, and particularly between about 10 μm and about 30 μm 90 .

[0142] 3. The writing instrument according to any one of the preceding embodiments, wherein the refill comprises less than about 1% by weight, more specifically less than about 0.5% by weight, more specifically less than about 0.2% by weight of TiO2, and particularly is substantially free or free of TiO2.

[0143] 4. The writing instrument according to any one of the preceding embodiments, wherein the refill comprises less than about 0.5% by weight, more specifically less than about 0.2% by weight of FeS, and particularly is substantially free or free of FeS.

[0144] 5. The writing instrument according to any one of the preceding embodiments, wherein the refill contains at least one additional pigment from the group consisting of BaSO4, CaCO3, ZnS, ZnO, and ZrO2, and in particular wherein the refill contains all of the pigments BaSO4, CaCO3, and ZnS.

[0145] 6. The writing instrument according to embodiment 5, wherein the ratio of BaSO4 to Ca2SiO4 is between about 8:1 and about 1:1, more specifically between about 6:1 and about 1.5:1, and in particular between about 4:1 and about 2:1.

[0146] 7. The writing instrument according to any one of embodiments 5 or 6, wherein the ratio of BaSO4 to CaCO3 is between about 50:1 and about 2:1, more specifically between about 30:1 and about 5:1, and in particular between about 20:1 and about 7:1.

[0147] 8. The writing instrument according to any one of embodiments 5 to 7, wherein the ratio of BaSO4 to the total content of ZnS, ZnO, and ZrO2 is between about 5:1 and about 1:3, more specifically between about 3:1 and about 1:2, and in particular between about 2:1 and about 1:1.

[0148] 9. The writing instrument according to any one of embodiments 5 to 8, wherein the ratio of Ca2SiO4 to CaCO3 is between about 8:1 and about 1:1, more specifically between about 6:1 and about 1.5:1, and in particular between about 4:1 and about 2:1.

[0149] 10. The writing instrument according to any one of embodiments 5 to 9, wherein the ratio of the total content of ZnS, ZnO, and ZrO2 to Ca2SiO4 is between about 5:1 and about 1:3, more specifically between about 4:1 and about 1:2, and in particular between about 3:1 and about 1:1.

[0150] 11. The writing instrument according to any one of embodiments 5 to 10, wherein the ratio of the total content of ZnS, ZnO, and ZrO2 to CaCO3 is between about 20:1 and about 1:1, more specifically between about 15:1 and about 2:1, and in particular between about 10:1 and about 3:1.

[0151] 12. The writing instrument according to any one of embodiments 5 to 11, wherein the BaSO4 particles have a D between about 0.1 μm and about 10 μm, more specifically between about 0.3 μm and about 3 μm, and in particular between about 0.5 μm and about 1.5 μm 50 。

[0152] 13. A writing instrument according to any one of embodiments 5 to 12, wherein the CaCO3 particles have a D that is between about 10 nm and about 300 nm, more specifically between about 30 nm and about 200 nm, and particularly between about 50 nm and about 150 nm. 50 。

[0153] 14. A writing instrument according to any one of embodiments 5 to 13, wherein the ZnS, ZnO, and / or ZrO2 particles have a D50 that is between about 30 nm and about 1000 nm, more specifically between about 50 nm and about 700 nm, and particularly between about 250 nm and about 450 nm.

[0154] 15. A writing instrument according to any one of embodiments 5 to 14, wherein the BaSO4 particles have a D that is between about 0.15 μm and about 15 μm, more specifically between about 0.5 μm and about 5 μm, and particularly between about 1.3 μm and about 2.3 μm. 90 。

[0155] 16. A writing instrument according to any one of embodiments 5 to 15, wherein the CaCO3 particles have a D that is between about 50 nm and about 1500 nm, more specifically between about 150 nm and about 700 nm, and particularly between about 250 nm and about 400 nm. 90 。

[0156] 17. A writing instrument according to any one of embodiments 5 to 16, wherein the ZnS, ZnO, and / or ZrO2 particles have a D that is between about 50 nm and about 1500 nm, more specifically between about 300 nm and about 1250 nm, and particularly between about 700 nm and about 1000 nm. 90 。

[0157] 18. A writing instrument according to any one of embodiments 5 to 17, wherein the BaSO4 particles have a BET value measured according to DIN ISO 9277:2014-01 that is between about 0.5 m 2 / g and about 20 m 2 / g, more specifically between about 1.5 m 2 / g and about 8 m 2 / g, and particularly about 2 m 2 / g and about 6 m 2 / g.

[0158] 19. The writing instrument according to any one of embodiments 5 to 18, wherein the CaCO3 particles have a BET value of between about 5 m 2 / g and about 150 m 2 / g, more specifically between about 10 m 2 / g and about 70 m 2 / g, and particularly about 20 m 2 / g and about 40 m 2 / g, measured according to DIN ISO 9277:2014-01.

[0159] 20. The writing instrument according to any one of embodiments 5 to 19, wherein the ZnS, ZnO and / or ZrO2 particles have a BET value of between about 1 m 2 / g and about 20 m 2 / g, more specifically between about 3 m 2 / g and about 15 m 2 / g, and particularly about 5 m 2 / g and about 11 m 2 / g, measured according to DIN ISO 9277:2014-01.

[0160] 21. The writing instrument according to any one of the preceding embodiments, wherein the refill contains between about 0.1 wt% and about 24 wt%, more specifically between about 1.0 wt% and about 12 wt%, of Ca2SiO4 relative to the total weight of the refill.

[0161] 22. The writing instrument according to any one of the preceding embodiments, wherein the writing instrument is a handheld writing instrument.

[0162] 23. The writing instrument according to any one of the preceding embodiments, wherein the refill has a diameter between about 5 mm and about 35 mm, more specifically between about 6 mm and about 20 mm, and particularly between about 7 mm and about 12 mm.

[0163] 24. The writing instrument according to any one of the preceding embodiments, wherein the writing instrument includes a housing, and the refill is included within the housing.

[0164] 25. The writing instrument according to any one of embodiments 1 to 22 or 24, wherein the refill has a diameter between about 2.0 mm and about 4.5 mm, more specifically between about 2.3 mm and about 4.2 mm, and particularly between about 2.8 mm and about 4.0 mm.

[0165] 26. The writing instrument according to any of the preceding embodiments, wherein the refill comprises one or more waxes in an amount of between about 10% and about 95% by weight relative to the total weight of the refill.

[0166] 27. The writing instrument according to embodiment 26, wherein the refill comprises the one or more waxes in an amount of between about 50% and about 95% by weight, more specifically between about 60% and about 90% by weight, and particularly between about 70% and about 85% by weight relative to the total weight of the refill.

[0167] 28. The writing instrument according to embodiment 26, wherein the refill comprises the one or more waxes in an amount of between about 10% and about 45% by weight, more specifically between about 15% and about 40% by weight, and particularly between about 20% and about 30% by weight relative to the total weight of the refill.

[0168] 29. The writing instrument according to any of the preceding embodiments, wherein the refill comprises a polymer in an amount of between about 10% and about 45% by weight, more specifically between about 15% and about 35% by weight, and particularly between about 18.5% and about 27% by weight relative to the total weight of the refill, more specifically a thermoplastic, even more specifically an olefin, and particularly polyethylene or polypropylene.

[0169] 30. The writing instrument according to any of the preceding embodiments, wherein the refill comprises a fatty acid or a salt thereof in an amount of between about 1% and about 20% by weight, more specifically between about 3% and about 17% by weight, and particularly between about 5% and about 15% by weight relative to the total weight of the refill.

[0170] 31. The writing instrument according to any of the preceding embodiments, wherein the refill comprises a fatty acid salt, wherein the fatty acid or salt comprises a monovalent straight-chain or branched-chain saturated or unsaturated carboxylate having between about 8 and about 24 carbon atoms, more specifically a monovalent straight-chain saturated carboxylate having between about 16 and about 20 carbon atoms, and particularly stearic acid, calcium stearate, zinc stearate, or a mixture thereof.

[0171] 32. The writing instrument according to any of the preceding embodiments, wherein the refill comprises a filler, particularly hydrated aluminosilicate and / or alkali metal carbonate and / or alkaline earth metal carbonate.

[0172] 33. The writing instrument according to embodiment 32, wherein the refill contains a filler in an amount of between about 10% and about 50% by weight, more specifically between about 17% and about 40% by weight, and particularly between about 23.5% and about 32% by weight, based on the total weight of the refill.

[0173] 34. The writing instrument according to embodiment 32, wherein the refill contains a hydrated aluminosilicate, more specifically a layered hydrated aluminosilicate, and particularly kaolinite, in an amount of between about 5% and about 30% by weight, more specifically between about 10% and about 25% by weight, and particularly between about 15% and about 20% by weight, based on the total weight of the refill.

[0174] 35. The writing instrument according to any one of the preceding embodiments, wherein the refill contains an alkali metal carbonate and / or an alkaline earth metal carbonate, more specifically an alkaline earth metal carbonate, in an amount of between about 5% and about 20% by weight, more specifically between about 7% and about 15% by weight, and particularly between about 8.5% and about 12% by weight, based on the total weight of the refill.

[0175] 36. The writing instrument according to any one of the preceding embodiments, wherein the refill contains a processing aid, more specifically a lubricant, and particularly pentaerythritol tetrastearate, in an amount of between about 2% and about 20% by weight, more specifically between about 4% and about 15% by weight, and particularly between about 7% and about 11% by weight, based on the total weight of the refill.

[0176] 37. The writing instrument according to any one of the preceding embodiments, wherein the refill contains a plasticizer, more specifically a phthalate, and particularly an alkyl benzyl phthalate C7-C9, in an amount of between about 0.5% and about 5% by weight, more specifically between about 1% and about 3.5% by weight, and particularly between about 1.5% and about 2.5% by weight, based on the total weight of the refill.

[0177] 38. The writing instrument according to any one of the preceding embodiments, wherein the refill contains one or more colorants in an amount of between about 0.05% and about 10% by weight, more specifically between about 0.05% and about 7% by weight, and particularly between about 0.1% and about 5% by weight, based on the total weight of the refill.

[0178] 39. A writing instrument according to any one of embodiments 1 to 33 or 35 to 38, wherein the refill comprises between about 5 wt% and about 80 wt%, more specifically between about 10 wt% and about 60 wt%, even more specifically between about 15 wt% and about 55 wt%, and particularly between about 15 wt% and about 50 wt% of the total weight of the refill of a hydrated aluminosilicate, more specifically a layered hydrated aluminosilicate, and particularly kaolinite.

[0179] 40. A writing instrument according to any one of embodiments 1 to 37 or 39, wherein the refill comprises between about 5 wt% and about 30 wt%, more specifically between about 10 wt% and about 25 wt%, and particularly between about 13 wt% and about 17 wt% of the total weight of the refill of one or more colorants.

[0180] 41. A writing instrument according to any of the foregoing embodiments, wherein the refill comprises between about 3 wt% and about 50 wt%, more specifically between about 10 wt% and about 50 wt%, more specifically between about 15 wt% and about 45 wt%, and particularly between about 20 wt% and about 40 wt% of the total weight of the refill of a binder, more specifically a polymeric binder, and particularly a styrenic polymer such as polystyrene and / or acrylonitrile butadiene styrene.

Claims

1. A writing instrument, the writing instrument comprising a refill, wherein the refill comprises: Ca2SiO4 particles of at least about 0.01% by weight relative to the total weight of the refill, wherein the Ca2SiO4 particles have a D between about 5 μm and about 15 μm 50 , and a BET value between about 25 m 2 / g and about 55 m 2 / g.

2. The writing instrument according to claim 1, wherein the Ca2SiO4 particles have a D that is between about 3 μm and about 150 μm, more specifically between about 7 μm and about 50 μm, and particularly between about 10 μm and about 30 μm 90 .

3. The writing instrument according to any one of the preceding claims, wherein the refill comprises less than about 1% by weight, more particularly less than about 0.5% by weight, more particularly less than about 0.2% by weight of TiO2, and in particular is substantially free or free of TiO2.

4. The writing instrument according to any one of the preceding claims, wherein the refill comprises less than about 0.5% by weight, more particularly less than about 0.2% by weight of FeS, and in particular is substantially free or free of FeS.

5. The writing instrument according to any one of the preceding claims, wherein the refill comprises at least one additional pigment from the group of BaSO4, CaCO3, ZnS, ZnO and ZrO2, and in particular wherein the refill comprises all of the pigments BaSO4, CaCO3 and ZnS.

6. The writing instrument according to claim 5, wherein the ratio of BaSO4 to Ca2SiO4 is between about 8:1 and about 1:1, more particularly between about 6:1 and about 1.5:1, and in particular between about 4:1 and about 2:

1.

7. The writing instrument according to any one of claims 5 or 6, wherein the ratio of Ca2SiO4 to CaCO3 is between about 8:1 and about 1:1, more particularly between about 6:1 and about 1.5:1, and in particular between about 4:1 and about 2:

1.

8. The writing instrument according to any one of claims 5 to 7, wherein the total content of ZnS, ZnO and ZrO2 relative to Ca2SiO4 is between about 5:1 and about 1:3, more particularly between about 4:1 and about 1:2, and in particular between about 3:1 and about 1:

1.

9. The writing instrument according to any one of claims 5 to 8, wherein the BaSO4 particles have a D between about 0.1 μm and about 10 μm, more specifically between about 0.3 μm and about 3 μm, particularly between about 0.5 μm and about 1.5 μm 50 .

10. A writing instrument according to any one of claims 5 to 9, wherein the CaCO3 particles have a D of between about 10 nm and about 300 nm, more specifically between about 30 nm and about 200 nm, and particularly between about 50 nm and about 150 nm 50 .

11. The writing instrument according to any one of the preceding claims, wherein the refill comprises between about 0.1% by weight and about 24% by weight, more particularly between about 0.5% by weight and about 18% by weight, and in particular between about 1.0% by weight and about 12% by weight of Ca2SiO4 relative to the total weight of the refill.

12. The writing instrument according to any one of the preceding claims, wherein the refill comprises one or more waxes in an amount between about 10% by weight and about 95% by weight relative to the total weight of the refill.

13. The writing instrument according to any one of the preceding claims, wherein the refill comprises between about 10% by weight and about 45% by weight, more particularly between about 15% by weight and about 35% by weight, and in particular between about 18.5% by weight and about 27% by weight of a polymer, more particularly a thermoplastic, even more particularly an olefin, and in particular polyethylene or polypropylene, relative to the total weight of the refill.

14. A writing instrument according to any one of the preceding claims, wherein the refill comprises a fatty acid or a salt thereof in an amount of between about 1 wt% and about 20 wt%, more specifically between about 3 wt% and about 17 wt%, and particularly between about 5 wt% and about 15 wt% relative to the total weight of the refill.

15. A writing instrument according to any one of the preceding claims, wherein the refill comprises a binder in an amount of between about 3 wt% and about 50 wt%, more specifically between about 10 wt% and about 50 wt%, more specifically between about 15 wt% and about 45 wt%, and particularly between about 20 wt% and about 40 wt% relative to the total weight of the refill, more specifically a polymeric binder, and particularly a styrenic polymer such as polystyrene and / or acrylonitrile butadiene styrene.

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