Inkjet printing method

Abstract

The present invention relates to a method for manufacturing an inkjet-printed substrate, wherein a liquid treatment composition comprising at least one acid and an ink are deposited onto a substrate simultaneously or consecutively by inkjet printing, wherein the substrate comprises a coating layer comprising a salifiable alkaline or alkaline earth compound.

Claims

1. A method for manufacturing an inkjet-printed substrate comprising the following steps: a) providing a substrate, wherein the substrate comprises on at least one side a coating layer comprising a salifiable alkaline or alkaline earth compound, b) providing a liquid treatment composition comprising an acid that forms CO.sub.2 when it reacts with a salifiable alkaline or alkaline earth compound, c) providing an ink, d) depositing the liquid treatment composition onto the coating layer by inkjet printing so that the acid in the liquid treatment composition reacts with the salifiable alkaline or alkaline earth compound in the coating layer and forms a first pattern, and e) depositing the ink onto the coating layer by inkjet printing to form a second pattern, wherein the liquid treatment composition and the ink are deposited simultaneously or consecutively and the first pattern and the second pattern overlap at least partially.

2. The method of claim 1, wherein the first pattern and the second pattern overlap by at least 50%.

3. The method of claim 1, wherein the first pattern and the second pattern overlap by at least 90%.

4. The method of claim 1, wherein the first pattern and the second pattern overlap by at least 95%.

5. The method of claim 1, wherein the substrate of step a) is prepared by: i) applying a coating composition comprising a salifiable alkaline or alkaline earth compound on at least one side of the substrate to form a coating layer, and ii) drying the coating layer.

6. The method of claim 1, wherein the substrate is selected from the group consisting of paper, cardboard, containerboard, plastic, non-wovens, cellophane, textile, wood, metal, glass, mica plate, marble, calcite, nitrocellulose, natural stone, composite stone, brick, concrete, laminates, and any composites thereof.

7. The method of claim 1, wherein the substrate is paper, cardboard, containerboard, or plastic.

8. The method of claim 1, wherein the salifiable alkaline or alkaline earth compound is an alkaline or alkaline earth oxide, an alkaline or alkaline earth hydroxide, an alkaline or alkaline earth alkoxide, an alkaline or alkaline earth methylcarbonate, an alkaline or alkaline earth hydroxycarbonate, an alkaline or alkaline earth bicarbonate, an alkaline or alkaline earth carbonate, or any mixture thereof.

9. The method of claim 1, wherein the salifiable alkaline or alkaline earth compound is an alkaline or alkaline earth carbonate.

10. The method of claim 1, wherein the salifiable alkaline or alkaline earth compound is lithium carbonate, sodium carbonate, potassium carbonate, magnesium carbonate, calcium magnesium carbonate, calcium carbonate, or any mixture thereof.

11. The method of claim 1, wherein the salifiable alkaline or alkaline earth compound is a ground calcium carbonate, a precipitated calcium carbonate, a surface-treated calcium carbonate, or any mixture thereof.

12. The method of claim 1, wherein the salifiable alkaline or alkaline earth compound is in form of particles having a weight median particle size d.sub.50 from 15 nm to 200 m.

13. The method of claim 1, wherein the salifiable alkaline or alkaline earth compound is in form of particles having a weight median particle size d.sub.50 from 50 nm to 50 m.

14. The method of claim 1, wherein the salifiable alkaline or alkaline earth compound is in form of particles having a weight median particle size d.sub.50 from 100 nm to 2 m.

15. The method of claim 1, wherein the acid is selected from the group consisting of hydrochloric acid, sulphuric acid, sulphurous acid, phosphoric acid, citric acid, oxalic acid, acetic acid, formic acid, sulphamic acid, tartaric acid, phytic acid, boric acid, succinic acid, suberic acid, benzoic acid, adipic acid, pimelic acid, azelaic acid, sebaic acid, isocitric acid, aconitic acid, propane-1,2,3-tricarboxylic acid, trimesic acid, glycolic acid, lactic acid, mandelic acid, acidic organosulfur compounds, acidic organophosphorus compounds, and any mixture thereof.

16. The method of claim 1, wherein the acid is selected from the group consisting of hydrochloric acid, sulphuric acid, sulphurous acid, phosphoric acid, oxalic acid, boric acid, suberic acid, succinic acid, sulphamic acid, tartaric acid, and any mixture thereof.

17. The method of claim 1, wherein the acid is phosphoric acid, sulphuric acid, or a mixture thereof.

18. The method of claim 1, wherein the liquid treatment composition comprises the acid in an amount from 0.1 to 100 wt.-%, based on the total weight of the liquid treatment composition.

19. The method of claim 1, wherein the liquid treatment composition comprises the acid in an amount from 1 to 80 wt.-%, based on the total weight of the liquid treatment composition.

20. The method of claim 1, wherein the liquid treatment composition comprises the acid in an amount from 10 to 50 wt.-%, based on the total weight of the liquid treatment composition.

21. The method of claim 1, wherein the liquid treatment composition is deposited onto the coating layer in form of a one-dimensional bar code, a two-dimensional bar code, a three-dimensional bar code, a security mark, a number, a letter, an alphanumerical symbol, a text, a logo, an image, a shape, or a design.

22. An inkjet-printed substrate formed by the method according to claim 1.

23. A wall paper, packaging product, a decorative product, an artistic product, a gift wrap paper product, an advertisement paper or poster, a business card, a manual, a warranty sheet or card comprising the substrate according to claim 22.

Description

DESCRIPTION OF THE FIGURES

(1) FIG. 1 shows a text, which was inkjet printed according to the method of the present invention by employing an inkjet formulation comprising a liquid treatment composition and an ink, and a magnified section thereof recorded with an optical microscope.

(2) FIG. 2 shows a text, which was inkjet printed according to a conventional method using a conventional inkjet ink, and a magnified section thereof recorded with an optical microscope.

(3) FIG. 3 shows a two-dimensional bar code, which was inkjet printed according to the method of the present invention (top) and a magnification thereof recorded with an optical microscope (bottom), wherein an inkjet formulation comprising a liquid treatment composition and an ink was used.

(4) FIG. 4 shows a two-dimensional bar code, which was inkjet printed according to a conventional method using a conventional inkjet ink (top) and a magnification thereof recorded with an optical microscope (bottom).

(5) FIG. 5 shows an optical microscope picture of letters, which were inkjet printed according to the method of the present invention by employing an inkjet formulation comprising a liquid treatment composition and an ink.

(6) FIG. 6 shows an optical microscope picture of a grid, wherein the right part of the grid was inkjet printed according to the method of the present invention by depositing a liquid treatment composition and an ink consecutively.

(7) FIG. 7 shows an optical microscope picture of a grid, wherein the left part was inkjet printed according to the method of the present invention by depositing a liquid treatment composition and an ink consecutively.

(8) FIG. 8 shows an optical microscope picture of a grid, which was inkjet printed according to the method of the present invention by depositing a liquid treatment composition and an ink consecutively.

EXAMPLES

1. Optical Microscope Pictures

(9) The prepared inkjet prints were examined by a Leica MZ16A stereomicroscope (Leica Microsystems Ltd., Switzerland).

2. Materials

(10) Salifiable Alkaline Earth Compounds

(11) CC1: ground calcium carbonate (d.sub.50: 0.7 m, d.sub.98: 5 m), pre-dispersed slurry with solids content of 78%, commercially available from Omya AG, Switzerland. CC2: ground calcium carbonate (d.sub.50: 0.6 m, d.sub.98: 4 m), pre-dispersed slurry with solids content of 71.5%, commercially available from Omya AG, Switzerland. CC3: ground calcium carbonate (d.sub.50: 1.5 m, d.sub.98: 10 m), pre-dispersed slurry with solids content of 78%, commercially available from Omya AG, Switzerland. CC4: ground calcium carbonate (d.sub.50: 0.5 m, d.sub.98: 3 m), pre-dispersed slurry with solids content of 78%, commercially available from Omya AG, Switzerland. KA1: pre-dispersed kaolin slurry with solids content of 72%, fineness: residue on a 45 m sieve (ISO 787/7), particles <2 m (Sedigraph 5120), commercially available from Omya AG, Switzerland.
Binders B1: Starch (C*-Film 07311), commercially available from Cargill, USA. B2: Styrene-butadiene latex (Styronal D628), commercially available from BASF, Germany.
Inkjet Formulations and Inks F1: 41 wt.-% phosphoric acid, 23 wt.-% ethanol, 35 wt.-% water, and 1 wt.-% gardenia blue (product number OP0154, commercially available from Omya Hamburg GmbH, Germany) (wt.-% are based on the total weight of the inkjet formulation). F2: 41 wt.-% phosphoric acid, 23 wt.-% ethanol, 35 wt.-% water, and 0.1 wt.-% amaranth red (product code 06409, commercially available from Fluka, Sigma-Aldrich Corp., USA) (wt.-% are based on the total weight of the inkjet formulations). Ink 1: Black dye based ink (Oc KK01-E27 Black, commercially available from Oc Printing Systems GmbH & Co, KG, Germany), Solids content: 6.3 wt.-%, water content: 55.1 wt.-%, solvent content: 38.6 wt.-% (wt.-% are based on the total amount of the ink). The solvent consisted mainly of propylenglycol and butyldiglycol. Ink 2: Black pigment based ink (Oc KK01-E27 Black, commercially available from Oc Printing Systems GmbH & Co. KG, Germany). Solids content: 6.5 wt.-%, water content: 47.7 wt.-%, solvent content: 45.8 wt.-% (wt.-% are based on the total amount of the ink). The solvent consisted mainly of diethylenglycol and butyldiglycol.

3. Examples

Example 1Inkjet Printing of Letters and Two-Dimensional Bar Codes

(12) A double coated baseboard having a basis weight of 300 g/m.sup.2 was used as substrate. The pre-coat of the double coated baseboard had a coat weight of 15 g/m.sup.2 and was composed of 80 pph CC3, 20 pph KA1, and 11 pph B2. The top coat of the double coated baseboard had a coat weight of 10 g/m.sup.2 and was composed of 80 pph CC1, 20 pph KA1, and 12 pph B2.

(13) The liquid treatment composition and the ink were deposited onto the coating layer simultaneously in form of inkjet formulation F1.

(14) A text and a two-dimensional bar-code were created on the coating layer by inkjet printing using a Dimatix Materials Printer (DMP) of Fujifilm Dimatix Inc., USA, with a cartridge-based inkjet printhead having a drop volume of 10 pl. The print direction was from left to right, one row (line) at a time. The inkjet formulation F1 was applied onto the substrates with a drop volume of 10 pl and drop spacing of 25 m. The print resolution was about 1000 dpi.

(15) As a comparative example, the same text and two-dimensional bar code was inkjet printed onto the substrate by using a conventional inkjet ink (HP 364 magenta dye, Hewlett-Packard Company, USA) instead of the inkjet formulation of the present invention.

(16) The results of said prints were inspected microscopically.

(17) FIGS. 1 to 4 show optical microscope images of the substrates that were printed with the inkjet formulation of the present invention and with the prior art inkjet ink. While a high quality print image with a clear and precise imprint is obtained by using the inventive inkjet formulation (FIG. 1), the printed image of the comparative print shown in FIG. 2 is degraded due to bleeding of the inkjet ink, which results in a poor print resolution. The same was observed for the printed two-dimensional bar code. The bar code printed by the inventive method, shown in FIG. 3 is clear, precise and has a high resolution, while the comparative print shown in FIG. 4 is degraded and of poor resolution.

Example 2Inkjet Printing on Offset Paper

(18) A low weight coated (LWC) offset paper (basis weight: 75 g/m.sup.2) comprising a coating layer being composed of 70 pph of CC2, 30 pph KA1, 5 pph B2, and 3 pph B1 was used as substrate.

(19) The liquid treatment composition and the ink were deposited onto the coating layer simultaneously in form of inkjet formulation F2.

(20) A text was created on the coating layer by inkjet printing using a Dimatix Materials Printer (DMP) of Fujifilm Dimatix Inc., USA, with a cartridge-based inkjet printhead having a drop volume of 10 pl. The print direction was from left to right, one row (line) at a time. The inkjet formulation was applied onto the substrate with a drop volume of 10 pl and a drop spacing of 30 m. The print resolution was 850 dpi.

(21) The result of said print was inspected microscopically. As can be gathered from the microscope image shown in FIG. 5, a high quality print image with a clear and precise imprint was obtained with the inventive method.

Example 3Inkjet Printing of Grids onto Square-Shaped Patterns

(22) A double coated paper having a basis weight of 90 g/m.sup.2 was used as substrate. The pre-coat of the double coated baseboard had a coat weight of 10 g/m.sup.2 and was composed of 100 pph CC3, and 6 pph B2. The top coat of the double coated baseboard had a coat weight of 8.5 g/m.sup.2 and was composed of 100 pph CC4, and 8 pph B2.

(23) First and second patterns were created on the coating layer by inkjet printing using a Dimatix Materials Printer (DMP) of Fujifilm Dimatix Inc., USA, with a cartridge-based inkjet printhead having a drop volume of 10 pl. The print direction was from left to right, one row (line) at a time.

(24) Firstly, a liquid treatment composition containing 41 wt.-% phosphoric acid, 23 wt.-% ethanol, and 36 wt.-% water (wt.-% are based on the total weight of the liquid treatment composition) was deposited onto a part of the coating layer in form of a square using a drop spacing of 20 m (sample 1) or 30 m (sample 2) in order to form a first pattern. Subsequently, ink 1 was deposited onto the substrate in form of a grid using a drop spacing of 25 m in order to form a second pattern, wherein the grid was aligned such that it was printed within the square-shaped pattern as well as onto the remaining parts of the substrate, on which the square-shaped pattern was not present.

(25) The results of the inkjet prints were inspected microscopically.

(26) FIG. 6 shows an optical microscope picture of sample 1, wherein the right part of the black second grid was deposited onto the first square-shaped pattern printed with the liquid treatment composition (inventive example). The left part of the black second grid was deposited directly onto the coating layer of the substrate (comparative example). While the right part of the grid is very clear and precise, the left part of the grid is broader and more frayed due to bleeding of the ink.

(27) FIG. 7 shows an optical microscope picture of sample 2, wherein the left part of the black second grid was deposited onto the first square-shaped pattern printed with the liquid treatment composition (inventive example). The right part of the black second grid was deposited directly onto the coating layer of the substrate (comparative example). While the left part of the grid is very clear and precise, the right part of the grid is broader and more frayed due to bleeding of the ink.

(28) FIGS. 6 and 7 confirm that by applying the inventive method high quality inkjet prints with a clear and precise imprint can be formed.

Example 4Inkjet Printing of a Grid onto a Grid

(29) A double coated paper having a basis weight of 90 g/m.sup.2 was used as substrate. The pre-coat of the double coated baseboard had a coat weight of 10 g/m.sup.2 and was composed of 100 pph CC3, and 6 pph B2. The top coat of the double coated baseboard had a coat weight of 8.5 g/m.sup.2 and was composed of 100 pph CC4, and 8 pph B2.

(30) Grids were created on the coating layer by inkjet printing using a Dimatix Materials Printer (DMP) of Fujian Dimatix Inc., USA, with a cartridge-based inkjet printhead having a drop volume of 10 pl. The print direction was from left to right, one row (line) at a time.

(31) Firstly, a liquid treatment composition containing 41 wt.-% phosphoric acid, 23 wt.-% ethanol, and 36 wt.-% water (wt.-% are based on the total weight of the liquid treatment composition was deposited onto a part of the substrate in form of a first grid using a drop spacing of 25 m. Subsequently, ink 2 was deposited onto the substrate in form of a second grid using a drop spacing of 25 mm, wherein the second grid was aligned such that it was printed within the first grid.

(32) The result of the inkjet print was inspected microscopically. It can be gathered from FIG. 8 that due to a slight misalignment of the first and the second grid spreading of the ink downwards and rightwards was observed. No spreading upwards and leftwards was observed since those edges of the second grid are formed on the first grid. Thus, FIG. 8 confirms that by applying the inventive method high quality inkjet prints with a clear and precise imprint can be formed.