Ink jet printing method

Abstract

An ink jet printing method includes printing an image on a printing medium including a transparent substrate and an ink-receiving layer on one side of the transparent substrate by applying a first ink and a second ink onto the surface of the ink-receiving layer of the printing medium in such a manner that the first ink and the second ink are at least partially superposed one on the other. The first ink is an aqueous ink containing silver particles, and the second ink is an aqueous ink containing a dye. The particle size at 50% in the cumulative volume distribution of the silver particles is larger than the average pore size of the ink-receiving layer.

Claims

1. An ink jet printing method comprising: printing an image on a printing medium including a transparent substrate and an ink-receiving layer on one side of the transparent substrate by applying a first ink and a second ink onto the surface of the ink-receiving layer in such a manner that the first ink and the second ink are at least partially superposed one on the other, the first ink being an aqueous ink comprising silver particles, the second ink being an aqueous ink comprising a dye, wherein a particle size at 50% in a cumulative volume distribution of the silver particles is larger than an average pore size of the ink-receiving layer.

2. The ink jet printing method according to claim 1, wherein the ink-receiving layer absorbs ink at a volume of 0.4 mL/m.sup.2 or more.

3. The ink jet printing method according to claim 1, wherein the average pore size of the ink-receiving layer is 40 nm or less.

4. The ink jet printing method according to claim 1, wherein the ink-receiving layer has a thickness of 5.5 μm or more.

5. The ink jet printing method according to claim 1, wherein the ink-receiving layer comprises a binder and inorganic particles, and the proportion of the mass of the binder to the mass of the inorganic particles is 0.50 or less.

6. The ink jet printing method according to claim 1, wherein the dye contained in the second ink is present in the ink-receiving layer.

7. The ink jet printing method according to claim 1, wherein the first ink is applied to the printing medium after the application of the second ink.

8. The ink jet printing method according to claim 1, wherein the image is viewed from an opposite side of the printing medium on which the ink-receiving layer is disposed.

9. The ink jet printing method according to claim 1, wherein the transparent substrate is made of a polyester resin, a polyolefin resin, or a polyvinyl chloride resin.

10. The ink jet printing method according to claim 1, wherein a thickness of the transparent substrate is 1 μm or more to 5,000 μm or less.

11. The ink jet printing method according to claim 1, wherein the ink-receiving layer absorbs ink at a volume of 2.0 mL/m.sup.2 or less.

12. The ink jet printing method according to claim 1, wherein an average pore size of the ink-receiving layer is 10 nm or more to 30 nm or less.

13. The ink jet printing method according to claim 1, wherein the ink-receiving layer has a thickness of 30.0 μm or less.

14. The ink jet printing method according to claim 5, wherein a proportion of the mass of the binder to the mass of the inorganic particles is 0.05 or more.

15. The ink jet printing method according to claim 1, wherein a haze value of the printing medium is 60% or less.

16. The ink jet printing method according to claim 1, wherein a haze value of the printing medium is 30% or less.

17. The ink jet printing method according to claim 1, wherein a content of the silver particles in the first ink is 2.0% by mass or more to 15.0% by mass or less relative to the total mass of the first ink.

18. The ink jet printing method according to claim 1, wherein the particle size at 50% in a cumulative volume distribution of the silver particles is 10 nm or more to 150 nm or less.

19. The ink jet printing method according to claim 1, wherein a particle size at 90% in the cumulative distribution of silver particles is 10 nm or more to 200 nm or less.

20. The ink jet printing method according to claim 1, wherein a content of the dye in the second ink is 1.0% by mass or more to 10.0% by mass or less relative to the total mass of the first ink.

Description

EXAMPLES

(1) The subject matter of the present disclosure will be further described in detail with reference to the following Examples and Comparative Examples. However, it is not limited to the Examples. In the following description, “part(s)” and “%” are on a mass basis unless otherwise specified.

(2) Preparation of Inorganic Particle Dispersion Liquids

(3) Inorganic Particle Dispersion Liquid 1

(4) Into 160.0 g of pure water were added 40.0 g of hydrated alumina powder (DISPERAL HP14, produced by Sasol) and 0.6 g of methanesulfonic acid. These materials were stirred in a mixer for 30 minutes to yield inorganic particle dispersion liquid 1 containing 20.0% of hydrated alumina inorganic particles.

(5) Inorganic Particle Dispersion Liquid 2

(6) Inorganic particle dispersion liquid 2 was prepared in the same manner as inorganic particle dispersion liquid 1 except that the inorganic particles were replaced with hydrated alumina powder (DISPERAL HP22, produced by Sasol).

(7) Inorganic Particle Dispersion Liquid 3

(8) Inorganic particle dispersion liquid 3 was prepared in the same inorganic particle dispersion liquid 1 except that the inorganic particles were replaced with hydrated alumina powder (DISPERAL HP30, produced by Sasol).

(9) Inorganic Particle Dispersion Liquid 4

(10) Into 160.0 g of pure water were added 40.0 g of finned silica powder (AEROSIL 50, produced by EVONIK) and 2.0 g of SHALLOL DC-902 (produced by Dai-ichi Kogyo Seiyaku). These materials were stirred in a mixer for 30 minutes to yield inorganic particle dispersion liquid 4 containing 20.0% of silica inorganic particles.

(11) Preparation of Coating Liquids

(12) Polyvinyl alcohol (PVA 235, produced by Kuraray, polymerization degree: 3500, saponification degree: 88%) was dissolved as the binder in ion-exchanged water to yield a polyvinyl alcohol aqueous solution containing 8.0% of solids. The polyvinyl alcohol aqueous solution was mixed with each of the inorganic particle dispersion liquids shown in Table 1 so that the proportion ((binder)/(inorganic particles)) of the solids in the polyvinyl alcohol solution to the solids in the inorganic particle dispersion liquid would be the value shown in Table 1. The resulting mixture was mixed with 3.0% boric acid aqueous solution so that the boric acid solids would be 1.0% relative to the inorganic particle solids. Each coating liquid was thus prepared.

(13) TABLE-US-00001 TABLE 1 Coating liquid Coating liquid No. 1 2 3 4 5 6 Inorganic 1 2 3 4 1 1 particle dispersion liquid No. (Binder)/ 0.10 0.10 0.10 0.20 0.50 0.60 (Inorganic particles)
Preparation of Printing Media

(14) Each coating liquid was applied onto a 100 μm-thick transparent substrate shown in Table 2 so that the weight (g/m.sup.2) of the coating after drying could be the value shown in Table 2. The coating was then dried with hot air of 90° C. to yield a printing medium. Table 2 shows the haze value, the average pore size of the ink-receiving layer, the ink absorption of the ink-receiving layer, and the thickness of the ink-receiving layer together. These properties were each measured in a manner as described herein later. In Table 2, PET represents polyethylene terephthalate, PE represents polyethylene, and PVC represents polyvinyl chloride.

(15) TABLE-US-00002 TABLE 2 Preparation and Properties of Printing Media Printing medium No. 1 2 3 4 5 6 7 8 9 10 11 12 Substrate material PET PE PVC PET PET PET PET PET PET PET PET PET Coating liquid No. 1 1 1 2 3 4 1 1 1 5 6 1 Weight of coating 20.0 20.0 20.0 20.0 20.0 20.0 5.5 5.2 5.0 20.0 20.0 20.0 after drying (g/m.sup.2) Haze (%) 7 7 7 30 84 99 4 4 3 7 7 30 Average pore size (nm) 21 21 21 36 48 98 21 21 21 21 21 32 of ink-receiving layer Ink absorption (mL/m.sup.2) 1.7 1.7 1.7 1.9 1.5 3.3 0.4 0.3 1.7 1.7 1.7 1.9 of ink-receiving layer Thickness (μm) of ink- 20.0 20.0 20.0 20.0 20.0 20.0 5.5 5.2 5.0 20.0 20.0 20.0 receiving layer
Measurement of Haze

(16) The haze of the printing media was determined in accordance with JIS K 7105 and JIS K 7136 with a haze meter NDH 4000 (manufactured by Nippon Denshoku Industries).

(17) Measurement of Average Pore size

(18) The pore size of the ink-receiving layer was measured with a pore size distribution analyzer using gas permeation (POROMETER 3 Gz, manufactured by Quantachrome Instruments). The pore sizes of randomly selected 100 pores were measured, and the average of the 100 pore sizes was determined as the average pore size of the ink-receiving layer.

(19) Measurement of Ink Absorption

(20) There is known Bristow's Method specified in Standard No. 51 of JAPAN TAPPI, “Test Method for Liquid Absorption of Paper and Paperboard” (in Japanese) as a method for measuring the ink absorbency of printing media. Ink absorption was measured by Bristow's method.

(21) A predetermined amount of an ink (solvent) was introduced into a container having a slit having predetermined dimensions and was brought into contact with a printing medium cut into a rectangular shape and wound around a disk through the slit. Then, the disk was rotated with the container fixed so that the ink being transferred to the printing medium could form a band, and the area (length) of the ink band was measured. The rate (mL/m=′) of ink transferred to the printing medium per unit area was calculated from the area of the ink band. The obtained rate (mL/m.sup.2) represents the volume of the ink absorbed into the printing medium for a predetermined period. The predetermined period here is defined as the transfer period for which the ink was transferred. The transfer period (m.sup.1/2) corresponds to the period for which the slit and the printing medium are in contact with each other and is calculated from the rotational speed of the disk and the width of the slit. In the present disclosure, the ink absorption of a printing medium represents the ink absorption for a transfer period of 10 ms.sup.1/2.

(22) Preparation of Silver Particle Dispersion Liquids

(23) Silver particle dispersion liquids 1 to 3 (containing 20.0% of silver particles and 2.0% of a resin) were prepared according to the preparation method described in Example 2 disclosed in International Publication No. WO 008/049519. The D.sub.50 particle size was varied by varying the stirring speed for the preparation. Furthermore, silver particle dispersion liquid 4 (containing 20.0% of silver particles and 2.0% of a surfactant) was prepared according to the preparation method described in Example 2-2 disclosed in Japanese Patent Laid-Open No. 2004-285106. The D.sub.50 particle size of silver particles for each dispersion liquid was determined by dynamic light scattering and is shown in Table 3.

(24) Preparation of Aluminum Particle Dispersion Liquids

(25) Aluminum particle dispersion liquids 1 and 2 (each containing 20.0% of aluminum particles) were prepared according to the metallic pigment dispersion liquid reparation method described in the Examples disclosed in Japanese Patent Laid-Open No. 2010-18651. The D.sub.50 particle size was varied by varying dispersing conditions. The D.sub.50 particle size of aluminum particles was determined by dynamic light scattering and is shown in Table 3.

(26) D.sub.50 Measurement

(27) The D.sub.50 values of the silver particles and the aluminum particles were measured with a dynamic light scattering particle size distribution analyzer (Nanotrac UPA-EX150, manufactured by Nikkiso) under the conditions, SetZero: 30 s, number of measurement times: 3, measuring period: 180 s, shape: perfect sphere, and refractive index: 1.6.

(28) TABLE-US-00003 TABLE 3 Dispersion liquids D.sub.50 (nm) Silver particle dispersion liquid 1 32 Silver particle dispersion liquid 2 111 Silver particle dispersion liquid 3 150 Silver particle dispersion liquid 4 32 Aluminum particle dispersion liquid 1 1100 Aluminum particle dispersion liquid 2 32
Preparation of First Inks

(29) The constituents shown in Table 4 were mixed. After being sufficiently stirred, the mixture was subjected to pressure filtration through a filter having a pore size of 1.2 μm to yield a first ink. Acetylenol E100 is a nonionic surfactant produced by Kawaken Fine Chemical. The HLB value of Acetylenol E100 determined by the Griffin method is 13, Compound 1 was C.I. Acid blue 9, as shown below.

(30) TABLE-US-00004 TABLE 4 First Ink Composition First ink No. 1 2 3 4 5 6 7 Silver particle dispersion 1 50.0 50.0 Silver particle dispersion 2 50.0 Silver particle dispersion 3 50.0 Silver particle dispersion 4 50.0 Aluminum particle 50.0 dispersion 1 Aluminum particle 50.0 dispersion 2 Compound 1 5.0 Ethylene glycol 20.0 20.0 20.0 20.0 20.0 20.0 20.0 Acetylenol E100 0.2 0.2 0.2 0.2 0.2 0.2 0.2 Ion-exchanged water 29.8 29.8 29.8 29.8 24.8 29.8 29.8
Preparation of Second Inks
Preparation of Dye

(31) The following compounds were prepared, wherein although the structural formula shown below is compound 3 in the form of a free acid, compound 3 actually used was the potassium salt:

(32) Compound 1: C.I. Acid Blue 9

(33) Compound 2: C.I. Acid Red 249

(34) Compound 3: Compound represented by the following formula (2), synthesized according to the procedure disclosed in Japanese Patent Laid-Open No. 2016-108545:

(35) ##STR00001##
Preparation of Pigment Dispersion Liquid

(36) A styrene-acrylic acid copolymer (resin dispersant) having an acid value of 150 mg KOH/g and a weight average molecular weight of 8,000 was prepared. This copolymer (20.0 parts) was neutralized with an amount of potassium hydroxide equivalent to the acid value of the copolymer, and an appropriate amount of pure water was added to yield a resin dispersant aqueous solution containing 20.0% of resin (solids). Subsequently, 20.0 parts of a pigment (Monarch 1100 produced by Cabot), 10.0 parts of a resin dispersant aqueous solution, and 75.0 parts of pure water were mixed. The resulting mixture and 200 parts of zirconia beads of 0.3 mm in diameter were placed into a batch-type vertical sand mill (manufacture by Aimex) and agitated for 5 hours while being cooled with water. Then, after coarse particles were removed by centrifugation, the mixture was subjected to pressure filtration through a cellulose acetate filter having a pore size of 3.0 μm (manufactured by Advantec) to yield a pigment dispersion liquid containing 20.0% of pigment and 2.0% of a resin dispersant.

(37) Second Ink

(38) The constituents shown in Table 5 were mixed. After being sufficiently stirred, the mixture was subjected to pressure filtration through a filter having a pore size of 1.2 μm to yield a second ink Acetylenol E100 is a nonionic surfactant produced by Kawaken Fine Chemical.

(39) TABLE-US-00005 TABLE 5 Second Ink Composition Second ink No. 1 2 3 4 Compound 1 5.0 Compound 2 5.0 Compound 3 5.0 Pigment dispersion liquid 25.0 Glycerin 15.0 15.0 15.0 15.0 Ethylene glycol 10.0 10.0 10.0 10.0 Acetylenol E100 0.5 0.5 0.5 0.5 Ion-exchanged water 69.5 69.5 69.5 49.5
Treatment Agent

(40) A treatment agent was prepared which contains 15 parts of fumed silica powder (CAB-O-SPERSE PG002, produced by Cabot), 5 parts of urethane resin (UCUAT UWS-145, produced by Sanyo Chemical Industries), and 80 parts of ion-exchanged water.

(41) Examination

(42) An ink cartridge was charged with each set of a first ink and a second ink combined as shown in Table 6 and was mounted in an ink jet printing apparatus (PIXUS MG3630, manufactured by Canon) having a print head from which the inks are ejected by thermal energy. In the Examples, when an image is printed with the first ink and the second ink under the conditions where one ink droplet with a volume of about 11.2 pL was applied to a unit region of 1/1200 inch× 1/1200 inch, the printing duty of the resulting image is defined as 100%. In Examples 1 to 7 and 9 to 19 and Comparative Examples 1 to 5, 7, and 8, the second ink was applied onto the printing medium shown in Table 6 at a printing duty of 100% with the ink jet printing apparatus. Then, the first ink was applied at a printing duty of 100% so as to cover at least a portion of the region coated with the second ink. In Example 8 and Comparative Example 6, the first ink was applied onto the printing medium shown in Table 6 at a printing duty of 100% with the ink jet printing apparatus. Then, the second ink was applied at a printing duty of 100% so as to cover at least a portion of the region coated with the first ink. In Reference Example 1, after the treatment agent was applied onto the printing medium with a roller, the second ink was applied at a printing duty of 100%. The treatment agent was applied onto the printing medium at a rate of 1 g/m.sup.2. Then, the first ink was applied at a printing duty of 100% so as to cover at least a portion of the region coated with the second ink. The glossy paper used as the printing medium in Comparative Example 1 was Canon Photo Paper (Gloss Pro Platinum Grade, manufactured by Canon). For evaluation, A and B represent acceptable levels, and C represents unacceptable level. The evaluation results are shown in Table 6.

(43) Gloss of Image

(44) The definition (=L/w) of each printed image was measured with a gonio-spectrophotometer GSP-2 (manufactured by Murakami Color Research Laboratory), wherein L represents the highest of the lightness values measured with the photoreceptor of the gonio-spectrophotometer, and w represents the width of acceptance angles at 2 points at which the lightness is one-half of L (L/2). When the definition is 0.2 or more, the lightness of visually observed images varies depending on the angle of observation. Such images are considered to be glossy.

(45) A: Definition was 4.0 or more.

(46) B: Definition was 3.0 or more to less than 4.0.

(47) C: Definition was less than 3.0.

(48) Coloration of Images

(49) The color of each image was measured with an integrating sphere spectrocolorimeter CM-2600d (manufactured by Konica Minolta) in the specular component included (SCI) mode as described below. a.sub.0* and b.sub.0* were measured for an image printed at a printing duty of 100% only with a first ink containing silver particles, and a.sub.1* and b.sub.1* were measured for an image printed with an ink containing silver particles and an ink containing a dye each at a printing duty of 100%. The color difference ΔE.sub.ab was calculated by substituting the measured values into the equation: color difference ΔE.sub.ab={(a.sub.1*−a*.sub.0).sup.2+(b.sub.1*−b*.sub.0).sup.2}.sup.1/2. a* and b* are each a value specified in the CIE (International Commission on Illumination) L*a*b* color system. When ΔE.sub.ab is 2.0 or more, the image looks like a color derived from the dye used but not silver. When ΔE.sub.ab is high, the image looks like a color satisfactorily derived from the dye used.

(50) A: ΔE.sub.ab was 6.0 or more.

(51) B: ΔE.sub.ab was 2.0 or more to less than 6.0.

(52) C: ΔE.sub.ab was less than 2.0.

(53) Bleeding in Images

(54) A region to which both the first ink and the second ink had been applied was visually Observed.

(55) A: No bleeding was observed.

(56) B: Bleeding was observed.

(57) TABLE-US-00006 TABLE 6 Examination results Combination Evaluation Printing First Second Color- Bleed- medium ink ink Gloss ation ing Example 1 1 1 1 A A A Example 2 2 1 1 A A A Example 3 3 1 1 A A A Example 4 1 2 1 A A A Example 5 1 1 2 A A A Example 6 1 1 3 A A A Example 7 1 3 1 A A A Example 8 1 1 1 A A A Example 9 4 4 1 A A A Example 10 5 4 1 B B A Example 11 6 4 1 B B A Example 12 1 1 1 A A A Example 13 1 1 1 A A A Example 14 1 1 1 B A A Example 15 7 1 1 A A A Example 16 8 1 1 A A B Example 17 9 1 1 A A B Example 18 10 1 1 A A A Example 19 11 1 1 A A B Comparative Example 1 Glossy 1 1 C C A paper Comparative Example 2 1 5 — C A A Comparative Example 3 1 6 1 C A A Comparative Example 4 1 7 1 C A A Comparative Example 5 1 1 4 C A A Comparative Example 6 1 1 4 A C A Comparative Example 7 4 1 1 C A A Comparative Example 8 12 1 1 C A A Reference Example 1 1 1 1 A A C

(58) While the present disclosure has described exemplary embodiments, it is to be understood that the claims are not limited to the disclosed exemplary embodiments. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions.

(59) This application claims priority to Japanese Patent Application No. 2017-210532 filed on Oct. 31, 2017 and No. 2018-173268 filed on Sep. 18, 2018, which are hereby incorporated by reference herein in their entirety.