AQUEOUS PIGMENTED INK

Abstract

An aqueous pigmented ink for use in a capillary reservoir system comprises at least one pigment, at least one water-dispersible, film-forming component, about 0.5 to about 4.5 wt % of at least one suspension substance and about 0.01 to about 0.5 wt % of a gel former combination in an aqueous vehicle, the gel former combination comprising at least one mineral gel former and at least one organic thickener.

Claims

1. An aqueous pigmented ink, the aqueous pigmented ink comprising: at least one pigment, at least one water-dispersible; film-forming component, at least one suspension substance, and a gel former combination in an aqueous vehicle, the gel former combination comprising at least one mineral gel former and at least one organic thickener.

2. The aqueous pigmented ink of claim 2, wherein the mineral gel former comprises at least one swellable layered silicate, and the organic thickener comprises at least one polysaccharide having thickening properties.

3. The aqueous pigmented ink of claim 2, wherein the at least one swellable layered silicate comprises at least one hectorite or a derivative thereof, and the at least one polysaccharide having thickening properties comprises at least one of xanthan gum, a derivative of xanthan gum, cellulose, and a derivative of cellulose.

4. The aqueous pigmented ink of claim 1, wherein the water-dispersible film-forming component comprises at least one acrylate-based film former.

5. The aqueous pigmented ink of claim 1, wherein the at least one suspension substance is fumed silica.

6. The aqueous pigmented ink of claim 1, wherein the gel former combination comprises hectorite, xanthan gum, and cellulose.

7. The aqueous pigmented ink of claim 1, wherein the at least one pigment comprises at least one effect pigment having a particle size of 5 μm to 100 μm.

8. The aqueous pigmented ink of claim 1, wherein the at least one suspension substance comprises 0.5-4.5 wt % of the aqueous pigmented ink, and the gel former combination comprises 0.01-0.5 wt % of the aqueous pigmented ink.

9. The aqueous pigmented ink of claim 1, wherein the gel former combination consists of hectorite, xanthan gum, and cellulose in a weight ratio of 0.8-1.2:0.8-1.2:0.8-1.2.

10. The aqueous pigmented ink of claim 1, wherein the at least one pigment comprises at least one effect pigment selected from the group consisting of flakes pearl pigment, borosilicate phlogopite, and combinations thereof.

11. A pen comprising a capillary reservoir system and an aqueous pigmented ink, the aqueous pigmented ink comprising: at least one pigment, at least one water-dispersible film-forming component, at least one suspension substance, and a gel former combination in an aqueous vehicle, the gel former combination comprising at least one mineral gel former and at least one organic thickener.

12. A refill container for a pen, the refill container comprising a reservoir and an aqueous pigmented ink, the aqueous pigmented ink comprising: at least one pigment, at least one water-dispersible film-forming component, at least one suspension substance, and a gel former combination in an aqueous vehicle, the gel former combination comprising at least one mineral gel former and at least one organic thickener.

13. The pen of claim 11, wherein the pen is a cosmetic pen.

14. The pen of claim 11, wherein the aqueous pigmented ink is disposed within the capillary reservoir system.

15. The pen of claim 11, wherein the capillary reservoir system comprises a reservoir containing the aqueous pigmented ink and an applicator in fluid connection with the reservoir.

16. The refill container of claim 12, wherein the aqueous pigmented ink is disposed within the reservoir.

17. The refill container of claim 12, wherein the pen comprises an applicator, and wherein the refill container is configured to be in fluid connection with the applicator.

18. The cosmetic pen of claim 13, wherein the aqueous pigmented ink is disposed within the capillary reservoir system.

19. The cosmetic pen of claim 13, wherein the capillary reservoir system comprises a reservoir containing the aqueous pigmented ink and an applicator in fluid connection with the reservoir.

20. The aqueous pigmented ink of claim 1, wherein the at least one suspension substance comprises 1-3 wt % of the aqueous pigmented ink, and the gel former combination comprises 0.01-0.25 wt % of the aqueous pigmented ink.

Description

EXAMPLE 1

[0046] An aqueous ink was produced which contained as gel formers xanthan gum, hectorite and cellulose, as film former an aqueous dispersion of styrene/acrylates/ammonium methacrylate copolymer, as pigment mica 77019 and the iron oxides 77491/77492/77499. The ink also contained commonly used ingredients, such as surfactants, namely poloxamer 407, coco-glucosides and water, and also ethylhexylglycerol and tocopherol, phenoxyethanol and potassium sorbate as a preservative system, and additionally citric acid to establish the pH, which is established suitably in a range from about 5.5 to 6.5, i.e. slightly acidic. The pH of the ink of the invention is not critical; the stabilizer system of the invention, composed of suspension substances and gel formers, is stable from acid to basic. As the skilled person is aware, it may be advantageous when using acrylates to establish a slightly basic or slightly acidic environment and to not allow the environment to become more strongly acidic, in order to prevent any change in the solubility. The skilled person is able to determine the most suitable pH range in each case, by routine experiments. For experiments, this ink was admixed with varying amounts of silica as suspension substance, with the water content being adapted accordingly in each case (ad 100). The formula is shown in Table 1 below.

TABLE-US-00001 TABLE 1 Amount Ingredient (parts by weight) Methylpropanediol 2.375 Butylene glycol 8 Xanthan gum + hectorite + cellulose 1:1:1 0.1 Poloxamer 407 2 Coco-glucosides 1.5 Styrene/acrylates/ammonium methacrylate copolymer 25 (40% aqueous dispersion) Pigment (mica 77019, iron oxides 77491, 77492, 10 77499)* Ethylhexylglycerol + tocopherol 0.1 Phenoxyethanol 0.6 Potassium sorbate 0.475 Citric acid 1.0 Aqua dest. ad 100 *Proportions according to desired shade

[0047] An aqueous ink was produced from the ingredients specified in Table 1. This ink was the base material for a series of test inks, each of which was admixed with different fractions of Aerosil fumed silica. The inks were then tested in a capillary writing system for their stability and fluidity. It was found that in the case of a comparative ink containing no suspension substance, the effect pigments underwent severe settlement and the ink was no longer writable after a short time.

[0048] The surprising effect of the addition of just about one percent by weight of suspension substance was a considerable improvement in both the stability and the fluidity. A fraction below 1 wt % was generally not enough to obtain the stability. A fraction of more than 3 wt %, problems with the fluidity were possible. An ink with 2 wt % of silica gave optimum properties.

EXAMPLE 2

[0049] An aqueous ink was produced which contained as suspension substance silica, as film former an aqueous dispersion of styrene/acrylates/ammonium methacrylate copolymer, as pigment mica 77019 and the iron oxides 77491/77492/77499. The ink also contained commonly used ingredients, such as surfactants, namely poloxamer 407, coco-glucosides and water, and also ethylhexylglycerol and tocopherol, phenoxyethanol and potassium sorbate as a preservative system, and additionally citric acid to establish the pH. For experiments, this ink was admixed with varying amounts of the gel formers xanthan gum, hectorite and cellulose, with the water content being adapted accordingly in each case (ad 100). The formula is shown in Table 2 below.

TABLE-US-00002 TABLE 2 Amount Ingredient (parts by weight) Methylpropanediol 2.375 Butylene glycol 8 Silica 2 Poloxamer 407 2 Coco-glucosides 1.5 Styrene/acrylates/ammonium methacrylate copolymer 25 (40% aqueous dispersion) Pigment (mica CI 77019, iron oxides 77491, 77492, 10 77499)* Ethylhexylglycerol + tocopherol 0.1 Phenoxyethanol 0.6 Potassium sorbate 0.475 Citric acid 1.0 Aqua dest. ad 100 *Proportions according to desired shade

[0050] An aqueous ink was produced from the ingredients specified in Table 2. This ink without gel former was then tested in a capillary writing system for its stability and fluidity. It was found that the pigments underwent severe settlement and the ink after a short time was no longer writable.

[0051] The ink was then admixed with different fractions of gel former combination (hectorite+xanthan gum+cellulose 1:1:1) and the influence thereof on the rheological behaviour of the ink, and the effect on the settlement stability and the ink flow in a capillary system, were investigated. It was found that for an addition of just about 0.05 wt %, an ink was obtained which had good ink flow and no settlement of pigments.

[0052] The results are summarized in Table 3, with the meaning of the symbols being as follows:

[0053] + no or virtually no settlement of pigments, good ink flow

[0054] 0 settlement of pigments and/or inadequate ink flow

[0055] − severe settlement of pigments and/or poor ink flow

[0056] nd not determined

TABLE-US-00003 TABLE 3 Fraction of rheological additives (hectorite + xanthan Fraction of gum + cellulose 1:1:1)** silica** 0 0.05 0.1 0.15 0.2 0 − − − − − 1 − − − − 0 1.5 − − − − 0 2 − − + + + 2.5 − 0 + 0 − 3 − + 0 − nd **in each case in wt %

[0057] The data in Table 3 shows that the amounts of rheological additives and silica added to an ink are very critical. Only if the fraction of suspension substance and the amount of rheological additives are harmonized with one another in accordance with the invention is an ink obtained wherein the pigments show little or no settlement and the ink flow is such as to allow the ink to be used for a capillary reservoir system.

[0058] It was found that the amount of suspension substance must not be higher than 4.5 wt % and that the gel former component is able to furnish the desired results only in very small fractions of about 0.05 to about 0.5 wt %. If suspension substances and/or gel formers are used outside the claimed limits, then in general either the settlement behaviour of the pigments or the fluidity of the ink, or both, is or are adversely affected, as shown by the experiments in Table 3.

EXAMPLE 3

[0059] An investigation looked at whether an acrylate copolymer makes a suitable organic thickener. Accordingly, a comparative ink was produced in accordance with Table 2, and was admixed with an acrylate copolymer as stabilizer, instead of the gel former combination of the invention. It emerged that the ink did indeed have a similar viscosity and a comparable flow behaviour to the inks described in Example 2. Nevertheless, the sample with the acrylate copolymer showed greater sedimentation of the pigments and therefore a much poorer ink flow in the capillary reservoir system. It was further found that the properties, because of the acrylate fraction, were heavily dependent on the pH of the composition.

[0060] In contrast, very good results were obtained when the ink as per the formula in Table 2 was admixed with a mixture of xanthan gum, hectorite and cellulose. In this case both the stability of the pigments and the flow behaviour in the capillary reservoir system were excellent.

[0061] The results are summarized in Table 4 below.

TABLE-US-00004 TABLE 4 Viscosity η Stabilizing component (mPas)*** Observations 1% silica + 1% acrylates 100 Severe settlement of copolymer pigments 1% silica + 2% acrylates 200 Settlement of pigments copolymer 1% silica + 3% acrylates 450 Stable to settling (in bulk), copolymer but virtually no ink flow in the capillary system 1% silica + 0.05% xanthan 180 Slight settlement of gum pigments, limited ink flow in the capillary system 1% silica + 0.1% xanthan 460 Stable to settlement (in gum bulk), no ink flow in the capillary system 1% silica + 0.1% acrylates/ 800 Settlement of pigments C10-30 alkyl acrylate crosspolymer 1% silica + 0.1% 80 Slight settlement of K-carrageenan pigments, good ink flow in the capillary system, not temperature-stable 1% silica + 0.03% xanthan 100 Stable to settling (in bulk), gum + 0.03% hectorite + good ink flow in capillary 0.03% cellulose system ***measured with a Physica MCR 301 rheometer at 25° C. and a shear rate of 1 s.sup.−1

EXAMPLE 4

[0062] A further investigation looked at whether the addition of xanthan gum as sole gel former is sufficient to obtain the desired properties. A comparative ink was produced as per Table 2 with 2% of silica (Aerosil, available commercially from Evonik), to which 0.1% of xanthan gum was added as stabilizer. This ink in fact had the lowest viscosity, and the pigments were also virtually stable to settling in the reservoir vessel. When, however, this ink was used in a capillary reservoir system, it exhibited poor flow behaviour. This ink was therefore not suitable for the intended purpose.

[0063] Further comparative experiments were carried out with inks having an effect agent fraction of 10% and a suspension substance content of 2% of fumed silica. Flow curves were recorded, and are shown in FIG. 1.

[0064] Although the inks have similar viscosities and a comparable flow behaviour in the rheogram, the sample with 0.3% of acrylate copolymer as rheological additive (plot with squares) exhibits poor ink flow in the pen system and significant sedimentation of the pigments in the ink. Ink quality, moreover, is heavily dependent on the pH of the composition. The ink with 0.1% of xanthan gum (plot with circles) shows the lowest viscosity in the rheogram, and the pigments are virtually stable to settling in bulk. In the pen system, nevertheless, this ink exhibits the poorest flow behaviour. Very good results in terms of pigment stability and flow behaviour in the pen are exhibited by inks containing 0.1% and 0.2% of a mixture of xanthan, hectorite and cellulose (plots with triangles and diamonds).