PROCESS OF PREPARATION OF AN AQUEOUS GEL INK WITH VARIABLE COLOR COMPRISING SILVER NANOPARTICLES

Abstract

The present invention concerns a process for preparing in situ an aqueous gel ink with variable color comprising the following steps: (i) preparing a gel-based matrix of aqueous ink comprising 0.005 to 0.1 mol.Math.L.sup.−1 of ester(s) of retinol represented by formula (I), and (ii) adding a solution of 0.002 to 0.05 mol.Math.L.sup.−1 silver salts (Ag.sup.+) to the gel-based matrix of aqueous ink prepared in step (i), to obtain an aqueous gel ink with variable color with silver nanoparticles dispersed therein. The present invention also relates to an aqueous gel ink with variable color obtained according to the process of the invention, comprising said ester of retinol represented by formula (I) and silver nanoparticles. The invention finally concerns a writing instrument comprising an aqueous gel ink with variable color according to the invention

Claims

1. A process for preparing in situ an aqueous gel ink with variable color comprising the following steps: preparing a gel-based matrix of aqueous ink comprising 0.005 to 0.1 mol.Math.L.sup.−1 of ester(s) of retinol represented by the following formula (I) ##STR00005## wherein R represents a C1-C6 aliphatic group, said aliphatic group being optionally substituted with at least one hydroxy, halogen, amino, C1-C3 alkyl and/or C1-C3 alkoxy group, said aliphatic group being a C1-C6 alkyl group, and (ii) adding a solution of 0.002 to 0.05 mol.Math.L.sup.−1 silver salts (Ag.sup.+) to the gel-based matrix of aqueous ink prepared in step (i), to obtain an aqueous gel ink with variable color with silver nanoparticles dispersed therein.

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

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

4. The aqueous gel ink according to claim 3, wherein the total amount of said ester(s) of retinol (I) ranges from 1 to 10% by weight relative to the total weight of the aqueous gel ink.

5. The aqueous gel ink according to claim 3, wherein the silver nanoparticles have an average particle size ranging from 20 to 150 nm.

6. The aqueous gel ink according to claim 3, wherein the silver nanoparticles are silver nanoparticles with the shape of spheres or polyhedral shape.

7. The aqueous gel ink according to claim 3, wherein the amount of silver nanoparticles ranges from 0.05 to 0.5% by weight relative to the total weight of the aqueous gel ink.

8. The aqueous gel ink according to claim 3, wherein the amount of water ranges from 50 to 95% by weight relative to the total weight of the aqueous gel ink.

9. The aqueous gel ink according to claim 3, further comprising a solvent, in an amount ranging from 5 to 35% by weight relative to the total weight of the aqueous gel ink.

10. The aqueous gel ink according to claim 3, 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.

11. The aqueous gel ink according to claim 3, 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, and/or an antifoam agent, in an amount ranging from 0.05 to 1% by weight relative to the total weight of the aqueous gel ink.

12. The aqueous gel ink according to claim 3, further comprising a rheology modifier, in an amount ranging from 0.08 to 2% by weight relative to the total weight of the aqueous gel ink.

13. A method of writing with an aqueous gel ink of variable color comprising the step of writing onto an absorbing support with an aqueous gel ink with variable color according to claim 3.

14. A writing instrument comprising: an axial barrel containing an aqueous gel ink with variable color according to claim 3, and a pen body which delivers the aqueous gel ink stored in the axial barrel.

15. A writing instrument according to claim 14, chosen in the group consisting of gel pens, felt pens, correction fluid, and markers.

16. The process according to claim 1, wherein the aliphatic group is a C1-C4 alkyl group.

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

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

19. The aqueous gel ink according to claim 3, wherein the silver nanoparticles have an average particle size ranging from 50 to 100 nm.

20. The aqueous gel ink according to claim 3, wherein the silver nanoparticles are silver nanoparticles with the shape of polyhedral shape.

Description

EXAMPLES

Example 1

Preparation of an Aqueous Gel Ink With Variable Color Based on Retinyl Acetate and Silver Nanoparticles, According to the Process of the Present Invention

[0085] 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 zo (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.Math.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.Math.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 2h30. 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.Math.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.

[0086] 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.

[0087] After the addition of the solution of silver nitrate by continuous injection, the color of the aqueous gel ink was dark grey.

[0088] 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 1509001:2015.

[0089] When the obtained aqueous gel ink with variable color was written on cellulosic paper, the color changed from dark grey to brown immediately (<1second) through a dissemination process of the silver nanoparticles on cellulosic paper.

[0090] Thus, the color of the ink is not the same before application on cellulosic paper and after application on cellulosic paper.

Comparative Example 1

Preparation of an Aqueous Gel Ink Based on Retinyl Palmitate and Silver 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.Math.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.Math.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 2h30. 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.Math.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 palmitate (CAS number: 79-81-2, from Sigma-Aldrich). The mixture was homogeneized with a homogeneizer mixer at a speed of 400 rpm during 10 minutes.

[0092] In a second step, 100 μL of a solution of silver nitrate (Carl Roth) (100 mM) was introduced into the mixture at a speed of 400 rpm during 5 to 10 minutes. After the addition of the solution of silver nitrate by continuous injection, the color of the aqueous gel ink was greyish white color.

[0093] The average particle size of the silver nanoparticles present within the aqueous gel ink is of 20 nm by analysis of 2D images (microscope: JEOL ARM 200), according to the standard IS09001:2015.

[0094] When the obtained aqueous gel ink was written on cellulosic paper, the color did not change and remained greyish white color.

[0095] Thus, the color of the ink is the same before application on cellulosic paper and after application on cellulosic paper.

Comparative Example 2

Preparation of an Aqueous Gel Ink with Fixed Color Based on Retinyl Acetate and Gold Nanoparticles

[0096] 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.Math.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.Math.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 2h30. Then, 0.30 g of Moussex S 9092 (antifoam agent) was added. The mixture was homogenized with a homogenizing mixer at a speed of 15 m.Math.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.

[0097] 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.

[0098] After the addition of the solution of gold (III) chloride trihydrate by continuous injection, the color of the aqueous gel ink was dark blue.

[0099] 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 IS09001:2015.

[0100] When the obtained aqueous gel ink was written on cellulosic paper, the color did not change and remained dark blue.

[0101] Thus, the color of the ink is the same before application on cellulosic paper and after application on cellulosic paper.