PROCESS OF PREPARATION OF AN AQUEOUS GEL INK WITH FIXED COLOR COMPRISING GOLD NANOPARTICLES

Abstract

The present invention concerns a process for preparing in situ an aqueous gel ink with fixed color comprising the following steps: (i) preparing a gel-based matrix of aqueous ink comprising ester(s) of retinol represented by formula (I), and (ii) adding a solution of gold salts (Au3+) to the gel-based matrix of aqueous ink prepared in step (i), to obtain an aqueous gel ink with fixed color with gold nanoparticles dispersed therein. The present invention also relates to an aqueous gel ink with fixed color obtained according to the process of the invention, comprising said ester of retinol represented by formula (I) and gold nanoparticles. The invention finally concerns a writing instrument comprising an aqueous gel ink with fixed color according to the invention.

##STR00001##

Claims

1. A process for preparing in situ an aqueous gel ink with fixed color comprising the following steps: (i) preparing a gel-based matrix of aqueous ink comprising ester(s) of retinol represented by the following formula (I): ##STR00006## Wherein R represents a C.sub.1-C.sub.6 aliphatic group, said aliphatic group being optionally substituted with at least one hydroxy, halogen, amino, C.sub.1-C.sub.3 alkyl and/or C.sub.1-C.sub.3 alkoxy group, said aliphatic group being a C.sub.1-C.sub.6 alkyl group, and (ii) adding a solution of gold salts (Au.sup.3+) to the gel-based matrix of aqueous ink prepared in step (i), to obtain an aqueous gel ink with fixed color with gold nanoparticles dispersed therein.

2. The process according to claim 1, wherein the ester of retinol (I) is retinyl acetate (vitamin A acetate).

3. The process according to claim 1, wherein the concentration of said ester(s) of retinol (I) in the gel-based matrix of aqueous ink of step (i) ranges from 0.10 to 0.50 mol.L.sup.−1.

4. The process according to claim 1, wherein the concentration of gold salts (Au.sup.3+) in the gel-based matrix of aqueous ink of step (ii) ranges from 0.004 to 0.05 mol.L.sup.−1.

5. An aqueous gel ink with fixed color obtained according to the process of claim 1, comprising said ester of retinol (I) and gold nanoparticles.

6. The aqueous gel ink according to claim 5, wherein the amount of said ester of retinol (I) ranges from 3 to 5.5% by weight relative to the total weight of the aqueous gel ink.

7. The aqueous gel ink according to claim 5, wherein the gold nanoparticles have an average particle size ranging from 10 to 250 nm.

8. The aqueous gel ink according to claim 5, wherein the gold nanoparticles are gold nanoparticles with the shape of spheres.

9. The aqueous gel ink according to claim 5, wherein the amount of gold nanoparticles ranges from 0.05 to 3% by weight relative to the total weight of the aqueous gel ink.

10. The aqueous gel ink according to claim 5, wherein the amount of water ranges from 50 to 95% by weight relative to the total weight of the aqueous gel ink.

11. The aqueous gel ink according to claim 5, further comprising a solvent chosen in the group consisting of glycol ethers, in an amount ranging from 5 to 35% by weight relative to the total weight of the aqueous gel ink.

12. The aqueous gel ink according to claim 5, further comprising an antimicrobial agent, in an amount ranging from 0.01 to 0.5% by weight relative to the total weight of the aqueous gel ink.

13. The aqueous gel ink according to claim 5, further comprising a corrosion inhibitor, in an amount ranging from 0.05 to 1% by weight relative to the total weight of the aqueous gel ink.

14. The aqueous gel ink according to claim 5, further comprising an antifoam agent, in an amount ranging from 0.05 to 1% by weight relative to the total weight of the aqueous gel ink and/or a rheology modifier, in an amount ranging from 0.08 to 2% by weight relative to the total weight of the aqueous gel ink.

15. A writing instrument comprising: an axial barrel containing an aqueous gel ink with fixed color according to claim 5, and a pen body which delivers the aqueous gel ink stored in the axial barrel, wherein the writing instrument is chosen in the group consisting of gel pens, felt pens, correction fluid, and markers.

16. The process of claim 1, wherein the aliphatic group is a C.sub.1-C.sub.4 alkyl group.

17. The process of claim 1, wherein the aliphatic group is unsubstituted.

18. The process of claim 1, wherein the aliphatic group is a methyl group.

19. The aqueous gel ink according to claim 5, wherein the gold nanoparticles have an average particle size ranging from 50 to 200 nm.

20. The writing instrument of claim 15, wherein the writing instrument is chosen in the group consisting of gel pens.

Description

EXAMPLES

Example 1

Preparation of an Aqueous Gel Ink with Fixed Color Based on Retinyl Acetate and Gold Nanoparticles, According to the Process of the Present Invention

[0084] In a first step (i), a gel-based matrix of aqueous ink was prepared by mixing 15 g of triethylene glycol (solvent), 4 g of polyethylene glycol (solvent), 0.19 g of Acticide® MBS (antimicrobial agent), and 0.10 g of Additie RC8221 (corrosion inhibitor). The mixture was homogeneized with a homogeneizer mixer at a speed of 15 m.s.sup.−1 during 15 minutes and heated at a temperature of 35° C. Then, 0.40 g of xanthan gum (rheology zo modifier) was added to the mixture. The mixture was homogenized with a homogenizing mixer at a speed of 15 m.s.sup.−1 during 15 minutes at a temperature of 35° C. 80.01 g of deionized water was slowly added to the mixture. The mixture was left to stand for 2 h30. Then, 0.30 g of Moussee S 9092 (antifoam agent) was added. The mixture was homogenized with a homogenizing mixer at a speed of 15 m.s.sup.−1 during 30 minutes at a temperature of 35° C. The gel-based matrix of aqueous ink obtained was cooled at room temperature (25° C.). Then, 1 mL of the obtained gel-based matrix of aqueous ink was mixed with 0.05 g of retinyl acetate (Sigma-Aldrich). The mixture was homogeneized with a homogeneizer mixer at a speed of 400 rpm during 15 minutes.

[0085] In a second step (ii), 100 μL of a solution of gold (III) chloride trihydrate (520918-1G from Sigma-Aldrich) (200 mM) was introduced into the mixture at a speed of 400 rpm during 15 minutes.

[0086] After the addition of the solution of gold (III) chloride trihydrate by continuous injection, the color of the aqueous gel ink was dark blue.

[0087] The average particle size of the gold nanoparticles present within the aqueous gel ink is of 50 nm by analysis of 2D images (microscope: JEOL ARM 200), according to the standard ISO9001:2015.

[0088] When the obtained aqueous gel ink with fixed color was written on cellulosic paper, the color appeared immediately dark blue and did not change after all.

[0089] Thus, the color of the ink is the same before application on cellulosic paper and after application on cellulosic paper. Furthermore, a visual assessment of the color of this aqueous gel ink was realized over time.

[0090] As can be seen from Table 1, the color of the aqueous gel ink did not change over time.

TABLE-US-00001 TABLE 1 Example 1 - Visual assessment of the color of aqueous gel ink over time 1 week (7 calendar Time 0 min 2 min 1 hour 1 day days) Color of the aqueous gel Dark Dark Dark Dark Dark ink before application on blue blue blue blue blue cellulosic paper Color of the aqueous gel Dark Dark Dark Dark Dark ink after application on blue Blue blue blue blue cellulosic paper

Comparative Example 1

Preparation of an Aqueous Gel Ink Based on Retinyl Palmitate and Gold Nanoparticles

[0091] In a first step, a gel-based matrix of aqueous ink was prepared by mixing 15 g of triethylene glycol (solvent), 4 g of polyethylene glycol (solvent), 0.19 g of Acticide® MBS (antimicrobial agent), and 0.10 g of Additie RC8221 (corrosion inhibitor). The mixture was homogeneized with a homogeneizer mixer at a speed of 15 m.s.sup.−1 during 15 minutes and heated at a temperature of 35° C. Then, 0.40 g of xanthan gum (rheology modifier) was added to the mixture. The mixture was homogenized with a homogenizing mixer at a speed of 15 m.s.sup.−1 during 15 minutes at a temperature of 35° C. 80,01 g of deionized water was slowly added to the mixture. The mixture was left to stand for 2 h30. Then, 0.30 g of Moussee S 9092 (antifoam agent) was added. The mixture was homogenized with a homogenizing mixer at a speed of 15 m.s.sup.−1 during 30 minutes at a temperature of 35° C. The gel-based matrix of aqueous ink obtained was cooled at room temperature (25° C.). Then, 1 mL of the obtained gel-based matrix of aqueous ink was mixed with 0.05 g of retinyl palmitate (CAS number: 79-81-2, from Sigma-Aldrich). The mixture was homogeneized with a homogeneizer mixer at a speed of 400 rpm during 15 minutes.

[0092] In a second step, 100 μL of a solution of gold (III) chloride trihydrate (520918-1G from Sigma-Aldrich) (200 mM) was introduced into the mixture at a speed of 400 rpm during 15 minutes. After the addition of the solution of gold (III) chloride trihydrate by continuous injection, the color of the aqueous gel ink was translucent yellow.

[0093] When the obtained aqueous gel ink was written on cellulosic paper, the color did not change and remained translucent yellow.

[0094] Furthermore, a visual assessment of the color of this aqueous gel ink on cellulosic paper was realized over time.

[0095] As can be seen from Table 2, the color of the aqueous gel ink on cellulosic paper appears brown after 1 week.

[0096] Thus, the color of the ink is not the same before application on cellulosic paper and after application on cellulosic paper over time.

TABLE-US-00002 TABLE 2 Comparative example 1 - Visual assessment of the color of aqueous gel ink over time. 1 week (7 calendar Time 0 min 2 min 1 hour 1 day days) Color of the aqueous gel Translucent Translucent Translucent Translucent Translucent ink before application on yellow yellow yellow yellow yellow cellulosic paper Color of the aqueous gel Translucent Translucent Translucent Translucent Brown ink after application on yellow yellow yellow yellow cellulosic paper

Comparative Example 2

Preparation of an Aqueous Gel Ink with Variable Color Based on Retinyl Acetate and Silver Nanoparticles

[0097] In a first step (i), a gel-based matrix of aqueous ink was prepared by mixing 15 g of triethylene glycol (solvent), 4 g of polyethylene glycol (solvent), 0.19 g of Acticide® MBS (antimicrobial agent), and 0.10 g of Additie RC8221 (corrosion inhibitor). The mixture was homogeneized with a homogeneizer mixer at a speed of 15 m.s.sup.−1 during 15 minutes and heated at a temperature of 35° C. Then, 0.40 g of xanthan gum (rheology modifier) was added to the mixture. The mixture was homogenized with a homogenizing mixer at a speed of 15 m.s.sup.−1 during 15 minutes at a temperature of 35° C. 80.01 g of deionized water was slowly added to the mixture. The mixture was left to stand for 2 h30. Then, 0.30 g of Moussee S 9092 (antifoam agent) was added. The mixture was homogenized with a homogenizing mixer at a speed of 15 m.s.sup.−1 during 30 minutes at a temperature of 35° C. The gel-based matrix of aqueous ink obtained was cooled at room temperature (25° C.). Then, 1 mL of the obtained gel-based matrix of aqueous ink was mixed with 0.025 g of retinyl acetate (Sigma-Aldrich). The mixture was homogeneized with a homogeneizer mixer at a speed of 400 rpm during 15 minutes.

[0098] In a second step (ii), 100 μL of a solution of silver nitrate (Carl Roth) (100 mM) was introduced into the mixture at a speed of 400 rpm during 15 minutes.

[0099] After the addition of the solution of silver nitrate by continuous injection, the color of the aqueous gel ink was dark grey.

[0100] The average particle size of the silver nanoparticles present within the aqueous gel ink is of 70 nm by analysis of 2D images (microscope: JEOL ARM 200), according to the standard ISO9001:2015.

[0101] When the obtained aqueous gel ink with variable color was written on cellulosic paper, the color changed immediately from dark grey to brown through a dissemination process of the silver nanoparticles on cellulosic paper (Table 3).

[0102] Thus, the color of the ink is not the same before application on cellulosic paper and after application on cellulosic paper over time.

[0103] Furthermore, a visual assessment of the color of this aqueous gel ink on cellulosic paper was realized over time (Table 3).

TABLE-US-00003 TABLE 3 Comparative example 2 - Visual assessment of the color of aqueous gel ink over time. 1 week (7 calendar Time 0 min 2 min 1 hour 1 day days) Color of the aqueous gel Dark Dark Dark Dark Dark ink before application on Grey grey grey grey grey cellulosic paper Color of the aqueous gel Brown Brown Brown Brown Brown ink after application on cellulosic paper