JP2002371208A - Intermediate transfer-type recording inkjet ink and inkjet recording method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an intermediate transfer-type inkjet ink and a recording method which can form images on a high quality level having excellent water resistance and light resistance, simultaneously, without bleeding and feathering and, in addition, having a broad color reproduction range on a recording medium. SOLUTION: The intermediate transfer-type inkjet ink comprises at least fine particle pigments having an average particle diameter, measured by the laser dynamic light scattering method, of 10-100 nm, a water-soluble organic solvent, and water. The intermediate transfer-type inkjet recording method uses the ink.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an intermediate transfer type recording ink-jet ink and an ink-jet recording method.

[0002]

2. Description of the Related Art A conventional ink jet recording method of writing a recording image by discharging ink droplets onto a recording medium is described below.
Although it is excellent in that the mechanism is simple and does not generate noise, it has problems in printing quality, such as different printing media due to differences in recording media, for example, differences in paper quality of the receiving paper, and discharge of the receiving paper. In such a case, there is a problem that a recorded image in a dry state is disturbed.

[0003] Accordingly, an intermediate transfer type in which ink droplets are temporarily ejected from an ink jet print head onto an intermediate transfer medium, most of the water content of the ink droplets is evaporated, and a concentrated ink image is transferred onto a recording medium such as paper. An ink jet recording method has been proposed, and this method has a feature that an output image is sharper than a method of performing recording by directly discharging ink onto a recording medium.

As a coloring material used in such an intermediate transfer type ink jet recording system, a pigment is desirable from the viewpoint of weather resistance. For example, in Japanese Patent Application Laid-Open No. 7-150087, water, a pigment, a water-soluble resin and a water-soluble resin are used. An intermediate transfer recording inkjet ink containing an organic solvent is disclosed.

[0005]

However, when a pigment is used as a coloring material, an image formed on a recording medium is more resistant to water, light, bleeding and bleeding than an image using a dye. There was a problem that the feathering property was insufficient and the color reproduction range was narrow. Accordingly, an object of the present invention is to provide an intermediate transfer type recording ink-jet ink capable of forming a high-quality image having a wide range of color reproduction without water, excellent light resistance, bleeding, and feathering on a recording medium. An object of the present invention is to provide an ink jet recording method.

[0006]

The above object is achieved by the present invention described below. That is, the present invention provides an intermediate transfer type recording characterized by comprising at least a fine particle pigment having an average particle size in a range of 10 to 100 nm by a laser dynamic light scattering method, a water-soluble organic solvent, and water. Provided are an inkjet ink (hereinafter simply referred to as “ink”) and an inkjet recording method for intermediate transfer recording using the ink. Further, the ink of the present invention further has a weight average molecular weight having a film forming property (hereinafter, simply referred to as “molecular weight”).
It is preferable to contain 5,000 to 500,000 resin components. Further, in the above method, it is preferable that the intermediate transfer medium has a heating mechanism.

[0007]

Next, the present invention will be described in more detail with reference to preferred embodiments. In a direct recording type ink jet recording method using a pigment as a coloring material, it is difficult to fix the surface of the pigment, particularly when the recording medium is plain paper. For example, when recording is performed using the same weight% of pigment as the dye, the image becomes inevitably light and cloudy.

In order to solve the problem, according to the present invention, in an ink using an intermediate transfer system, the average particle diameter of the pigment is 100%.
When the average particle diameter is less than 10 nm, the color gamut of the image transferred to the recording medium is considerably improved. And the viscosity of the ink may increase, so that the colorant has an average particle diameter of 10 to 100 nm as measured by a laser dynamic light scattering method.
An image is formed by an intermediate transfer method using a fine particle pigment in the range of the above, so that the ink is efficiently fixed to the vicinity of the surface of plain paper while having weather resistance, and there is no problem in the color reproduction range. It is possible to form.

Further, the ink of the present invention may further contain a resin component having a film forming property and a molecular weight of 5,000 to 500,000. By blending such a material, in addition to the above-described effects, not only excellent scratch resistance of the image on the recording medium can be exhibited, but further improvement in the color reproduction range can be expected. The mechanism of abrasion resistance development is based on increasing the binding force between the pigment particles, in which the resin is a coloring material, and further between the coloring material and the paper. This is considered to be due to the effect of preventing the pigment particles from aggregating at the treatment (removal of water) stage.

Here, when the molecular weight of the resin to be added is less than 5,000, the binding power of the resin becomes poor. On the other hand, when the molecular weight exceeds 500,000, the ejection stability of the ink in the ink jet head, clogging, etc. Concerns come out. The viscosity of the ink is desirably 1 to 10 cP, and a resin exceeding the viscosity is not desirable. Even if the molecular weight of the resin is large, in order to suppress the viscosity, it is desirable that the resin has as few water-soluble functional groups as possible, and as a more specific configuration, the resin is dispersed in water as a discontinuous phase. Desirably in form.

The amount of the pigment contained in the ink of the present invention is
In the range of 1 to 20%, preferably 2 to 12% by weight.
Use in box. With carbon black used for black ink
In some cases, furnaces manufactured by the furnace method or channel method
Carbon black with a primary particle size of 15 to 40
Clon), specific surface area by BET method is 50-300m ^Two
/ G, DBP oil absorption 40-150ml / 100g,
The departure has a value of 0.5 to 10% and a pH value of 2 to 9.
Things.

These carbon black pigments (CI.
Pigment Black 7), 2300, N
o. 900, MCF-88, No. 33, no. 40,
No. 45, no. 52, MA7, MA8, MA10
0, No. 2200B (Mitsubishi Kasei), Raven 70
0, 5750, 5250, 5000, 350
0, 1255 (all made in Colombia), Regal400
R, 330R, 1660R, MogulL, Monarch70
0, 800, 880, 900, 1000, 1
100, 1300, 1400 (all made by Cabot), color black FW1, FW2, FW2V,
FW18, FW200, S150, S160,
S170, Printtex 35, U, V, 14
0U, 140V, Special Black 6, 5, 5, 4
A and 4 (all made of Degussa) can be used, but the present invention is not limited thereto.

The pigments used in the yellow ink include C.I. I. Pigment Yellow 1, 2, 3, and 1
2, 13, 14, 14, 16, 17, 73, 7
4, 75, 83, 93, 95, 97, 9
8, 114, 128, 129, 151, 15
4 and the like, but are not limited to these.

The pigment used in the magenta ink includes C.I. I. Pigment Red 5, 7, 12, and 4
8 (Ca), 48 (Mn), 57 (Ca), 5
7: 1, 112, 123, 168, 184, and 202, but are not limited thereto.

[0015] Pigments used in cyan ink include:
C. I. Pigment Blue 1, 2, 3, and 15:
3, 15:34, 16, 16, 22, 60; I.
Butt Blue 4, 60 and the like, but are not limited thereto. Further, the pigment contained in the ink of the present invention can be used even if it is newly produced for the present invention.

In the present invention, the average particle size of the pigment ultrafine particles is determined by a laser dynamic light scattering method.
１００100 nm. These values are values when dispersed in an aqueous system, and specifically, ELS manufactured by Otsuka Electronics Co., Ltd.
It is a value measured using -8000.

In order to stably disperse the pigment used in the present invention in an aqueous system, various known means can be used. For example, means for dispersing in an aqueous system using a so-called dispersant (a water-soluble resin or an acid / alkali-soluble resin), means for using microencapsulation of a pigment by a method such as an interfacial polymerization method or an interfacial sedimentation method, Further, means for introducing an ionic functional group by subjecting the pigment surface to a plasma treatment, or applying a general surface treatment such as a method of performing a diazonium coupling and covalently bonding a functional group to the pigment surface, etc. But not limited thereto.

As the method for producing the ultrafine pigment used in the present invention, for example, the treatment time of the pigment dispersing step in an aqueous system is made longer than before, or the gas phase method described in JP-A-11-57458. However, the method is not limited thereto, and various known means can be used.

The viscosity of the black ink that can be used in the present invention is desirably from 1 to 10 cP. If the viscosity exceeds 10 cP, it is very difficult to eject the ink at a high frequency from the ink jet nozzle. In such a case, the pigment concentration and the solvent to be used are extremely limited, which is not feasible. More preferably 1.5 to
5 cP. The surface tension is preferably in the range of 20 to 60 dyne / cm, more preferably 25.
４５45 dyne / cm.

The resin having a film-forming property that can be used in the present invention preferably has a minimum film-forming temperature at least 5 ° C. lower than the heating temperature of the intermediate transfer medium.
The absolute value of the minimum film formation temperature is preferably 35 ° C. or less,
Above 35 ° C., very large power must be applied to heat the intermediate transfer medium. When the molecular weight is less than 5,000, the binding power of the resin becomes poor, and the molecular weight becomes less than 500.
If it exceeds 000, there are concerns about ink ejection stability and clogging of the ink jet head.
The viscosity of the final ink is 1 to 10
Desirably, it is cP, and a resin exceeding this is not desirable. Even if the molecular weight of the resin is large, in order to suppress the viscosity, it is desirable that the resin has as few water-soluble functional groups as possible, and as a more specific configuration, the resin is dispersed in water as a discontinuous phase. Desirably.
Specific examples of such materials include, but are not limited to, Joncryl450 (manufactured by Johnson Polymer), Movinyl 90000 (manufactured by Hoechst Gosei).

As the water-soluble organic solvent component of the ink, for example, water or a mixture of water and a water-soluble organic solvent is suitably used. Specific examples of the water-soluble organic solvent include, for example, dimethylformamide, dimethylacetamide Amides; ketones such as acetone; ethers such as tetrahydrofuran and dioxane; polyalkylene glycols such as polyethylene glycol and polypropylene glycol; ethylene glycol, propylene glycol, butylene glycol, triethylene glycol, 1,2,6- Alkylene glycols such as hexanetriol, thiodiglycol, hexylene glycol, diethylene glycol; ethylene glycol methyl ether, diethylene glycol monomethyl ether;
Lower alkyl ethers of polyhydric alcohols such as triethylene glycol monomethyl ether; monohydric alcohols such as ethanol, isopropyl alcohol, n-butyl alcohol, and isobutyl alcohol; glycerin; N-methyl-2-pyrrolidone; Dimethyl-
2-imidazolidinone; triethanolamine; sulfolane; dimethyl sulfoxide, and the like, and one or more of these are used. The content of the water-soluble organic solvent in the ink is not particularly limited.
0% by weight, more preferably 2 to 30% by weight is a suitable range.

The ink of the present invention as described above is useful for an ink-jet system for intermediate transfer recording. As the ink-jet system for intermediate transfer recording, any conventionally known system may be used. As an example, as shown in FIGS. 1 and 2, an inkjet head 2 and a backup roller 4 as a transfer unit are sequentially arranged from the upstream side in the rotation direction around a transfer drum 1 as a transfer medium. A heating unit (not shown) is arranged inside the transfer drum 1 to control the surface temperature of the transfer medium 1. The ink is supplied from the ink tank 3 to the head 2, the ink is ejected from the head 2, ink droplets are applied to the surface of the transfer medium 2, and an ink image 5 is formed. The ink image 5 is heated by a heating means incorporated in the transfer medium 1, and a considerable portion of the ink liquid medium is evaporated and removed.
Loses liquidity. While the ink image 5 is not completely dried, it is sent between the transfer drum 1 and the backup roller 4 according to the rotation of the transfer drum 1,
The ink image 5 is transferred to a recording medium 6 such as paper by the pressure of. The above example is one example, and the present invention is not limited to this example.

The ink-jet recording system used in the present invention may be any of the conventionally known systems.
As a preferable method, there is an ink jet recording method in which thermal energy corresponding to a recording signal is applied to ink in a chamber of a recording head and droplets are generated by the energy.

[0024]

EXAMPLES Next, the present invention will be described more specifically with reference to Reference Examples, Examples and Comparative Examples. Reference Example 1 <Preparation of Ink Set 1> Carbon black was used as a black pigment, and Pigment Yellow was used as a yellow pigment.
138, Pigment Red 122 as a magenta pigment and Pigment Blue 15: 3 as a cyan pigment.

30 parts by weight of pigment, styrene / acrylic acid /
6 parts by weight of an ethyl methacrylate copolymer (acid value 150, weight average molecular weight 5000, neutralization with 1.2 equivalents with KOH),
Three components of 267 parts by weight of ion-exchanged water are dispersed in a sand mill using zirconia beads as a grinding media for 30 hours, and then centrifuged (15000 rotations, 30 minutes), followed by a membrane filter having a pore diameter of 1.0 μm. 3 parts by weight of the non-volatile content, 5 parts by weight of glycerin, 5 parts by weight of diethylene glycol, 1 part by weight of acetylenol EH (trade name), and the remaining part of ion-exchanged water were mixed to obtain a dispersion having a pore diameter of 1 μm. The ink set 1 of each color of black, yellow, magenta, and cyan was prepared by filtration through a membrane filter. When the average particle size of the pigments in these inks was measured with a laser dynamic light scattering device manufactured by Otsuka Electronics Co., Ltd. ELS-8000, the black pigment 70 nm, the yellow pigment 67 nm, and the magenta pigment 65
nm, and the cyan pigment was 55 nm.

Reference Example 2 <Preparation of Ink Set 2> The dispersion obtained in the preparation of Ink Set 1 had a nonvolatile content of 3 parts by weight, glycerin 5 parts by weight, diethylene glycol 5 parts by weight, acetylenol E
H1 parts by weight, Joncryl450 (trade name; manufactured by Johnson Polymer Co., Ltd., weight average molecular weight 100,000 to 200,000, minimum film formation temperature 5)
The mixture was mixed with 2 parts by weight of not more than 0 ° C., a particle size of 0.08 μm) and the remaining part of ion-exchanged water, and filtered through a membrane filter having a pore diameter of 1 μm to prepare an ink set 2 of each color of black, yellow, magenta, and cyan.

Reference Example 3 <Preparation of Color Ink Set 3> JP-A-11-0574
The method for producing a surface-treated pigment ink by a gas phase method described in Example 3 of JP-A-58
gment Yellow 138, Pigment R as magenta pigment
ed 122, Pigment Blue 15: 3 as a cyan pigment
And oxygen as a working gas. The pigment obtained was fine particles having a carboxyl group introduced into the surface.

3 parts by weight of these fine particles, 5 parts by weight of glycerin, 5 parts by weight of diethylene glycol, acetylenol E
H1 part by weight and the rest of the ion-exchanged water were mixed, and the pH was adjusted to 7 to 8 with aqueous ammonia, followed by filtration through a membrane filter having a pore diameter of 1 μm to obtain yellow, magenta,
A color ink set 3 for each color of cyan was prepared. The average particle size of the pigments in these inks was measured by ELS-8000, a laser dynamic light scattering device manufactured by Otsuka Electronics Co., Ltd., which showed that the yellow pigment was 65 nm and the magenta pigment was 60 n.
m, the cyan pigment was 55 nm. Further, the black ink prepared in the ink set 1 was used as the black ink in the ink set 3.

[Reference Example 4] <Preparation of Ink Set 4> This is a preparation using a conventional sand mill. Carbon black is used as a black pigment, Pigment Yellow 138 is used as a yellow pigment, Pigment Red 122 is used as a magenta pigment, and cyan is used as a cyan pigment. Is
Pigment Blue 15: 3 was used.

30 parts by weight of pigment, styrene / acrylic acid /
3 parts by weight of an ethyl methacrylate copolymer (acid value 150, weight average molecular weight 7,000, neutralization with 1.2 equivalents with KOH),
The three components of 267 parts by weight of ion-exchanged water were dispersed as a grinding media in a sand mill using zirconia beads for 5 hours, and then subjected to centrifugation (5000 rpm, 30 minutes), followed by a membrane filter having a pore diameter of 2.5 μm. The dispersion obtained was mixed with 3 parts by weight of non-volatile components, 5 parts by weight of glycerin, 5 parts by weight of diethylene glycol, 1 part by weight of acetylenol EH, and the remainder of ion-exchanged water, and filtered through a membrane filter having a pore diameter of 1 μm. , Black, yellow, magenta, and cyan ink sets 4 were prepared.

The average particle size of the pigments in these inks was measured by ELS-80, a laser dynamic light scattering device manufactured by Otsuka Electronics Co., Ltd.
When measured at 00, the black pigment was 120 nm, the yellow pigment was 150 nm, the magenta pigment was 120 nm, and the cyan pigment was 110 nm.

Reference Example 5 <Preparation of Ink Set 5 (Dye Type)> Black Dye Fo
od Black 2, yellow dye Acid Yellow 23, magenta dye Acid Red 52, and cyan dye Acid Blue 9 were used. 3 parts by weight of dye, 5 parts by weight of glycerin,
5 parts by weight of diethylene glycol, acetylenol EH1
Parts by weight and the rest of the ion-exchanged water are mixed and the pore size is 0.2 μm
To prepare color ink sets 5 of black, yellow, magenta, and cyan.

Examples 1 and 3 and Comparative Examples 1 and 2 The ink-jet system for intermediate transfer recording performed in this example and the comparative example uses a transfer medium, as shown in FIGS. An ink jet head 2 and a backup roller 4 as a transfer unit are sequentially arranged from the upstream side in the rotation direction around the drum 1. The ink is supplied from the ink tank 3 to the head 2, and the ink is supplied at a rate of 2 per 600 dpi.
The ink is ejected from the inkjet head 2 having an ejection amount of 0 pl, and ink droplets are applied to the surface of the transfer medium 2 to form an ink image 5. The ink image 5 loses fluidity on the transfer drum by removing a part of the liquid medium of the ink by evaporation. The ink image 5 is sent between the transfer drum 1 and the backup roller 4 according to the rotation of the transfer drum 1 while the ink image 5 is not completely dried, and the pressure of the backup roller 4 transfers the ink image 5 to a recording medium 6 such as paper. did. Table 1 shows the ink sets used and the results obtained.

[Embodiment 2] As shown in FIGS. 1 and 2, the ink-jet system for intermediate transfer recording performed in this embodiment is an ink-jet system which is arranged from the upstream side in the rotation direction around a transfer drum 1 as a transfer medium. A head 2 and a backup roller 4 as a transfer unit are sequentially arranged. Also,
A heating unit (not shown) is disposed inside the transfer drum 1.
The surface temperature of the transfer medium 1 is heated to 40 ° C. The ink is supplied from the ink tank 3 to the head 2, the ink is discharged from the inkjet head 2 having a discharge amount of 20 pl per 600 dpi, and a droplet of the ink is applied to the surface of the transfer medium 2 to form the ink image 5. You. The ink image 5 is heated by a heating means incorporated in the transfer medium 1, and a considerable portion of the ink liquid medium is removed by evaporation, and the ink image 5 loses fluidity. The ink image 5 is sent between the transfer drum 1 and the backup roller 4 according to the rotation of the transfer drum 1 while the ink image 5 is not completely dried, and the pressure of the backup roller 4 transfers the ink image 5 to a recording medium 6 such as paper. did. Table 1 shows the ink sets used and the results obtained.

Comparative Example 3 Using the ink jet heads used in Examples 1, 3 and Comparative Example 1, printing was directly performed on the recording medium 6 without using a transfer drum. Table 1 shows the ink sets used and the results obtained. The evaluation was performed on the following items based on the following criteria.

"Color reproduction range" Y, M, C, R, G, B,
Each solid patch of Bk was printed, and its color development was visually evaluated. ：: Very vivid. Δ: Relatively bright. ×: Not very vivid.

"Image uniformity" Y, M, C, R, G, B,
Each solid patch of Bk was printed, and the uniformity of the solid was evaluated. ：: Very uniform. Δ: Unevenness is generated and uneven.

"Water resistance" Y, M, C, R, G, B, Bk
Each solid patch was printed, and water was dropped on the printed surface with a dropper to evaluate the outflow of ink. ：: No problem. X: The outflow of the ink is severe.

"Light fastness" Y, M, C, R, G, B, Bk
Each solid patch was printed and charged for 100 hours in an ultraviolet irradiation device manufactured by Atlas Co., Ltd., and the degree of fading was evaluated. ：: ΔE is within 10 ×: ΔE is 10 or more.

"Scratch resistance" Y, M, C, R, G, B, B
Each solid patch of k was printed, and the printed surface was touched with a finger to evaluate the degree of stain on the printed surface. ：: No stain at all. Δ: Slightly stained, but not so noticeable. ×: considerable stain is generated.

[0041]

[0042]

According to the present invention as described above, it is possible to form a high-quality image having excellent water resistance and light resistance, free of bleeding and feathering, and having a wide color reproduction range on a recording medium.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating an intermediate transfer method.

FIG. 2 is a diagram illustrating an intermediate transfer method.

[Explanation of symbols]

 1: intermediate transfer medium 2: ink jet head 3: ink tank 4: backup roller 5: ink image 6: recording medium

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Claims (4)

[Claims] 1. An intermediate transfer recording ink jet comprising at least a fine particle pigment having an average particle size in the range of 10 to 100 nm as measured by a laser dynamic light scattering method, a water-soluble organic solvent, and water. ink. 2. A weight-average molecular weight of 5 having a film-forming property.
The intermediate transfer recording ink jet ink according to claim 1, comprising a resin component of 000 to 500,000. 3. An ink jet recording method, comprising: forming a desired image on an intermediate transfer medium using the ink according to claim 1; and transferring the image to a recording medium. 4. The ink jet recording method according to claim 3, wherein the image formed on the intermediate transfer medium is heated and then transferred to a recording medium.