JPH0732721A - Ink jet recording method - Google Patents

Abstract

PURPOSE:To provide an ink image excellent in fastness on a recording medium by transferring the ink image on a transfer medium to the recording medium under low transfer pressure in a transfer type ink jet printer. CONSTITUTION:An ink jet recording method consists of a process writing ink containing at least water, a colorant and a resin emulsion with an MFT (minimum filming temp.) of 50 deg.C or higher on a transfer drum 1 whose surface temp. is heated to the MFT of the resin emulsion or higher, a process concentrating the ink image 50 on the transfer drum 1 and a process transferring the ink image 50 to recording paper 6.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to recording in a transfer type ink jet printer which ejects ink droplets from a recording head to form an ink image on a transfer medium and then transfers the ink image onto the recording medium to obtain an ink image on the recording medium. Regarding the method.

[0002]

2. Description of the Related Art A conventional ink jet recording method of ejecting ink droplets onto a recording medium to write a recorded image is excellent in that the mechanism is simple and noise is not generated. For example, there is a problem in printing quality that the printing state is different depending on the paper quality of the transferred paper, and there is also a problem that the undried recording image is disturbed when the transferred paper is discharged.

The apparatus proposed by the applicant of the present invention in Japanese Patent Laid-Open No. 62-92849 has been improved on the basis of the transfer type printer disclosed in US Pat. No. 4,538,156, and ink droplets have been improved. Is once ejected onto a transfer medium, where most of the water in the ink droplets is evaporated and the concentrated ink is transferred onto a recording medium such as paper. Further, in U.S. Pat. No. 5,099,256, a similar printer with improved print quality was proposed, which not only solves the above-mentioned problems, but also enables extremely clear image formation.

Further, as conventional examples of inks using a resin emulsion, Japanese Patent Publication No. 62-1426 and Japanese Unexamined Patent Publication No. 4-18462 disclose fixability and fastness of an ink image formed on a recording medium. For the purpose, an ink composition comprising water, a pigment and a water-insoluble synthetic resin emulsion is described.

Further, the applicant of the present invention has filed Japanese Patent Application Laid-Open No. 3-160068.
In addition to the above effects, JP-A No. JP-A No. 2004-242242 contains a resin emulsion for the purpose of improving compatibility with plain paper, preventing nozzle clogging, and ensuring storage reliability.
The above ink composition was proposed.

[0006]

However, the conventional transfer type printer and the conventional transfer type printer using the ink containing the conventional resin emulsion have the following problems.

First, in order to realize good transfer without residual transfer or deformation of the ink image, regardless of the time from ink ejection to transfer or the print pattern, the pressing force of transfer becomes large. It is a point. This problem will be described in detail below.

Regarding the relationship between the concentration state of the ink image using the conventional ink and the transfer pressure, the transfer pressure tends to increase as the ink image is concentrated. That is, when the ink concentration is high, the adhesiveness of the ink image is reduced, and a large transfer pressure is required to transfer the ink image with low adhesiveness. Therefore, in order to transfer at a low pressure, it was necessary to make the degree of concentration as low as possible within a range in which tackiness capable of sufficient transfer was obtained.

On the other hand, in an actual apparatus, it is necessary to obtain a good concentrated state without transfer residue and ink image deformation in a short time. Therefore, the transfer medium is heated by a heater to accelerate evaporation of the solvent component of the ink. Let However, when the amount of heat of the heater that heats the transfer medium is set to an appropriate value and the entire ink image on the transfer medium is to be concentrated in such a manner that good transfer can be performed, scanning is performed with one nozzle head or a multi-nozzle head. However, the time from ink ejection to transfer differs depending on the place, and a difference occurs in the concentrated state. Furthermore, the concentration state of the ink image also varies depending on the print pattern of the ink image, that is, the amount of ink per unit area.

In order to obtain a good transfer regardless of such a difference in the concentration state, it is necessary to set the pressure value in accordance with the maximum concentration state of the ink image, and an excessive pressure is required. It was

Another problem is that it is difficult to ensure both the nozzle clogging of the recording head and the fastness of the printed matter such as abrasion resistance and water resistance.

In a conventional recording method using an ink mainly composed of water, in order to prevent clogging of nozzles, a coloring agent, a resin or the like which is a constituent component of the ink is water-soluble or hydrophilic. Therefore, after the ink image was fixed on the recording medium, the ink image was disturbed by coming into contact with water again, and the water resistance was not obtained.

Further, when the conventional ink containing a resin emulsion having an effect of improving the fastness and the conventional transfer type ink jet recording method are combined, the operating environment temperature of the apparatus is controlled by the heat source held in the printer. Since the temperature rises, it was possible to obtain the water resistance of the recorded image by forming the emulsion film, but then the nozzles of the recording head were clogged. On the other hand, if the emulsion film-forming property is lowered to secure the clogging property, the water resistance of the recorded image will be lost, and the nozzle clogging of the recording head will be secured and the abrasion resistance and water resistance of the print will be robust. It was difficult to achieve both sexes.

The present invention solves the above problems.
The purpose is to transfer the ink image obtained on the transfer medium onto the recording medium at a low pressure without being affected by the time from printing to transfer or the print pattern, and further, it is possible to transfer the ink image to the recording medium. Ensuring nozzle clogging and abrasion resistance of printed matter,
It is an object of the present invention to provide a new inkjet recording method capable of achieving both fastness such as water resistance.

[0015]

According to the ink jet recording method of the present invention, an ink containing at least water, a colorant, and a resin emulsion having an MFT of 50 ° C. or higher is ejected as an ink droplet from a recording head to form the resin emulsion. Minimum film formation temperature (MFT, Minimum Film Format-ion Temp
erature), a step of writing an ink image on a transfer medium heated to a temperature above, a step of evaporating a solvent component of the ink image on the transfer medium, and a step of transferring the ink image on the transfer medium to a recording medium. The method is characterized in that the heating temperature is 50 ° C. to 150 ° C. in the step of evaporating the solvent component of the ink image.

[0016]

In the ink jet recording method of the present invention, when the solvent component of the ink image on the transfer medium is evaporated by the heating means, the surface temperature of the transfer medium is set to be equal to or higher than the MFT of the resin emulsion contained in the ink, The film strength and adhesive strength of the ink image on the transfer medium are improved, and the ink image obtained on the transfer medium is transferred onto the recording medium at low pressure without being affected by the time from printing to transfer or the print pattern. It becomes possible to do.

In order to prevent clogging of the head, it is necessary that the MFT of the resin emulsion is higher than the temperature inside the head, and the temperature of the head is affected by the operating environment temperature of the apparatus. Therefore, the MFT of the resin emulsion is at a sufficiently high temperature (50
(° C or higher), and by setting the drum surface temperature to the MFT temperature or higher to form the ink layer as a heating film, it is possible to achieve both head clogging and robustness, which have been problems in the past.

Therefore, it is necessary that the surface temperature of the transfer medium is 50 ° C. or higher and the temperature of the resin emulsion in the ink is MFT or higher. When the MFT of the resin emulsion contained in the ink is less than 50 ° C., gelation of the ink is predicted to occur depending on the environmental temperature, and storage reliability cannot be ensured. Further, due to heat from the heated transfer medium and ambient environmental temperature, evaporation of ink components from the nozzles causes the resin emulsion to form a film, resulting in ejection failure, and the reliability of the head cannot be ensured.

Further, when the surface temperature of the transfer medium exceeds 150 ° C., the head temperature rises because the head is arranged in the vicinity of the transfer medium, and the viscosity increases due to evaporation of the solvent component in the ink from the nozzle and the ejection due to drying. It causes a defect and cannot secure the reliability of the head.

Therefore, the surface temperature of the transfer medium is 50 ° C. to 15 ° C.
0 ° C is desirable.

[0021]

EXAMPLES First, examples of the ink jet recording method of the present invention will be described in detail.

FIG. 1 is a perspective view showing the construction of a characteristic embodiment of a transfer type ink jet printer of the present invention, and FIG. 2 is a sectional view of FIG. Transfer drum 1 which is a transfer medium
Around the circumference of the ink jet recording head 2, a backup roller 3 which is a transfer unit, and a cleaner 8 for removing adhered matters on the transfer drum from the upstream side in the rotation direction.
Are arranged in sequence. A heating unit 7 is arranged inside the transfer drum 1.

The recording head 2 is an ink jet recording head of the type using a piezoelectric element and has a plurality of nozzles in the axial direction of the transfer drum 1. An ink container 21 is connected to the recording head 2 and ink is supplied as necessary.

The transfer drum 1 is formed by laminating an elastic layer 12 made of silicone rubber around a metal tube 11. A rubber material is suitable for the elastic layer 12, and among them,
It is desirable to use a material having a good mold release property that easily peels off the ink image, and having heat resistance and durability, and silicone rubber, fluororesin, fluorosilicone rubber or the like, or a modified product thereof is preferable. As other materials, chloroprene rubber, nitrile rubber, ethylene propylene rubber, natural rubber, styrene rubber, isoprene rubber, butadiene rubber,
Ethylene / propylene / butadiene polymer, nitrile butadiene rubber and the like can also be used.

Further, the elastic layer 12 may be formed by coating various surface materials (ink layer carrying surfaces) of the various rubber materials with various good release coating materials. As the coating material, a silicone coating or a fluorine coating is preferable.

The backup roller 3 is a metal roller made of aluminum, and is structured so that it can be pressed and released from the transfer drum 1 by a transfer pressure applying device (not shown). During pressing, the recording paper 6 is rotated in the direction of arrow B in the figure at the same speed as the peripheral speed of the transfer drum 1. The transfer load is
In this embodiment, it is about 0.6 kgf / cm.

The cleaner 8 is made of felt,
The transfer drum 1 is contacted with a predetermined pressure by a contact mechanism (not shown).

The heating means 7 is a rod-shaped halogen lamp 15
And a reflector 16 having an elliptical surface on the inner surface, and the halogen lamp 15 is arranged at the first focal point of the reflector 16.

In this embodiment, the surface temperature of the transfer medium was set to the following value.

Example 1: 80 ° C. Example 2: 90 ° C. Example 3: 100 ° C. The ink used in the recording method of the present invention is a resin emulsion having at least water, a coloring material, and MFT of 50 ° C. or higher. It is configured.

The ink composition is specifically shown below.

(Ink composition 1)

[0033]

[Table 1]

The ink was manufactured by the following procedure, but the invention is not limited to this. It is confirmed by microscopic observation that the aqueous dispersion composed of the colorant and the dispersant is in a monodispersed state, the resin emulsion and dipropylene glycol are added thereto, and further mixed and stirred for 30 minutes to completely mix them uniformly. . After adding additives such as preservatives and confirming complete dissolution, the dispersion was filtered through a membrane filter having a pore size of 10 μm to remove dust and coarse particles to obtain a recording ink. Finally, another filtration operation is effective in preventing the mixture of impurities.

Next, the operation will be described.

First, the ink image writing process will be described.
FIG. 3 is a diagram showing how an ink image is written. The recording head 2 used in this embodiment is a line-shaped recording head having nozzles over the entire printing area L, and one rotation of the transfer drum 1 writes an ink image for one page. Ink droplets 5 are selectively ejected from the nozzles of the recording head 2 according to a recording signal to form a desired ink image 50.

Next, the ink image 50 (ink droplet 5) formed on the transfer drum 1 by the recording head 2 is heated by the heating means 7 to a temperature higher than the MFT of the resin emulsion forming the ink. The heating means 7 is controlled by a temperature detector (not shown) so that the surface temperature of the transfer medium falls within a predetermined temperature range. The ink image on the transfer drum 1 is rapidly heated, the solvent component is evaporated, and the emulsion resin forms a film to form a sticky film. Also, in the case of conventional ink, the concentration state differs depending on the time elapsed from printing and the print pattern, and there is a difference in adhesiveness, but in the case of this ink, the ink image itself is not affected by the degree of concentration, and sufficient film strength and adhesiveness Since it has a function of holding the film, it is possible to maintain substantially uniform film strength and adhesiveness regardless of the elapsed time after printing and the printing pattern.

The resin emulsion contained in the ink of this embodiment has an MFT of 67 to 85 ° C., and the heating temperature is preferably MFT + 5 to 30 ° C.

MFT is the temperature at which the emulsion resin forms a continuous film, but in the case of a resin emulsion without a clear MFT, the Tg and softening point of the resin emulsion,
The melting temperature may be used instead. When the MFT is too high, DBP (dibutyl phthalate), DEP (diethyl phthalate), BBP (benzyl butyl phthalate), BPBG (butyl phthalyl butyl glycolate)
Or plasticizer such as butyl carbitol,
An organic solvent such as ethyl carbitol, triethylene glycol, dipropylene glycol or the like may be added as a film formation aid to adjust the MFT to a low level. However, the MFT of the ink composition must be 50 ° C. or higher.

Next, the transfer drum 1 and the backup roller 3
The recording paper 6 is passed through the abutting portion of the recording paper 6 and the applied pressure to transfer the ink image 50 on the transfer drum 1 to the recording paper 6. At this time, since the ink image has uniform adhesiveness, it is not necessary to set the transfer pressure in the maximum concentrated state. Therefore, an image can be obtained on the recording paper 6 with a low pressure.

More specifically, the ink image 50 is
The recording paper 6 is in a film state with ink adhesion due to heating.
The ink is adhered along the unevenness of the fibers by the pressure being applied by the backup roller 3 at the same time when the ink comes into contact with. Further, when the solvent is completely removed, an ink image having excellent fastness can be obtained on the recording paper 6.

Here, the low pressure means 1 kg weight / in order to downsize the apparatus, reduce the cost of components such as the transfer drum 1 and the backup roller 3, and further improve the durability of the elastic layer on the surface of the transfer drum. cm or less, more preferably 0.6 kg weight / cm or less.

After the transfer of the ink image onto the recording paper 6 is completed, the transfer drum 1 moves to a portion in contact with the cleaner 8 as it rotates, and the residual ink on the transfer drum 1 is removed.

In the method of this embodiment described above, an ink having a uniform film strength and an adhesive property is obtained by containing a resin emulsion in the ink and heating the ink on the transfer medium at a temperature higher than the MFT of the resin emulsion. By forming an image and adhering the ink image to the fibers of the recording paper, it is possible to obtain a film having uniform film strength and adhesiveness irrespective of the heating time on the transfer medium or the print pattern. At the same time, there is an effect that the nozzle clogging of the recording head can be secured and an ink image with higher robustness can be obtained.

4 and 5 are views showing another ink image writing process applicable to this embodiment. FIG. 4 shows a format in which the recording head 2 is scanned in the direction of arrow C along a carriage shaft 20 parallel to the rotation axis of the transfer drum 1. The recording head 2 shown in FIG. 5 has a plurality of nozzles along the axial direction of the transfer drum 1, and while moving the recording head 2 in the rotation axis direction of the transfer drum 1 (direction D in the figure), In this method, the transfer drum 1 is rotated a predetermined number of times at a constant speed to form an ink image in a band shape. In these ink image writing methods, there is a difference in the time until heating by the heating means depending on the place where the ink image is formed on the transfer drum 1. However, as described above, by setting the heating amount of the heating means 7 to a temperature equal to or higher than the MFT of the resin emulsion contained in the ink, uniform film strength and adhesiveness are obtained irrespective of where the ink droplets are ejected. Can be obtained.

FIG. 6 is a diagram showing the structure of another transfer drum which can be used in this embodiment. Transfer drum 1
8 is a structure in which a heat insulating layer 13 is provided on the metal base tube 10, a sheet heater layer 19 as a heating means is provided thereon, and an elastic layer 17 made of the above-described material is further provided thereon. This shows a structure in which the heating means is integrally formed on the transfer drum.

In addition to the above-mentioned constitution, in order to improve the fixing strength of the ink image on the recording medium and to accelerate the evaporation of the solvent, heat fixing means such as roll heating and lamp heating can be used.

Next, specific composition examples of the ink applicable to the above-mentioned embodiments of the present invention will be shown.

Conventionally, water is mainly used as the ink solvent because of its low viscosity, excellent safety, easy handling, low cost, and no odor. As the ink material, pure water or ultrapure water that has undergone a purification process such as ion exchange or distillation is desirable.

A hydrophilic high-boiling point low-volatile solvent is added to the present ink in order to impart the effects of nozzle clogging resistance, moisture retention, and dispersion stability. Incidentally, the organic solvent as the film-forming auxiliary may be added for this purpose. Examples of the hydrophilic high-boiling point low-volatility solvent used in this ink include high-boiling point low-volatility solvents such as glycerin, ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, hexylene glycol, polyethylene glycol and polypropylene glycol. Polyhydric alcohols are used, or their monoether compounds, diether compounds, ester compounds,
For example, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether,
Diethylene glycol monobutyl ether and the like are used, and other N-methyl-2-pyrrolidone, 1.3-dimethylimidazolidinone, monoethanolamine, N, N-dimethylethanolamine, N, N-diethylethanolamine, diethanolamine, Nn-butyl A water-soluble organic solvent such as a nitrogen-containing organic solvent such as diethanolamine, triisopropanolamine, or triethanolamine can be added within the range where the flow of printing does not cause bleeding.

For the purpose of improving the drying property and fixing property with respect to water as a main solvent, ethanol, propanol,
Highly volatile monohydric alcohols such as isopropanol and butanol can be added in small amounts.

As the coloring agent, pigments, water-soluble dyes, disperse dyes, and water-insoluble dyes (when kneading and adding with resin emulsion) are used, and those having a good affinity with water as a main solvent or dispersions. Any agent can be used as long as it can be uniformly dispersed by the combined use of agents and the like.

Examples of pigments that can be used in the present ink include organic pigments and inorganic pigments. For black, carbon black (C.I., such as furnace black, lamp black, acetylene black, channel black) can be used. ．Pigment black 7) type or copper,
Examples include metals such as iron (CI Pigment Black 11) and titanium oxide, and organic pigments such as aniline black (CI Pigment Black 1). For color, C.I. I. Pigment Yellow 1 (Fast Yellow G), 3, 1
2 (this as yellow AAA), 13, 14, 17, 24, 3
4, 35, 37, 42 (yellow iron oxide), 53, 55, 8
1, 83 (This As Yellow HR), 95, 97, 98, 10
0, 101, 104, 108, 109, 110, 11
7, 120, 138, 153, C.I. I. Pigment Orange 5, 13, 16, 17, 3
6, 43, 51, C.I. I. Pigment Red 1, 2, 3, 5, 17, 22
(Brilliant First Scarlet), 23, 31, 38, 48: 2
(Permanentlet 2B (Ba)), 48: 2 (Permanentlet 2B (C)
a)), 48: 3 (permanentlet 2B (Sr)), 48: 4 (permanentlet 2B (Mn)), 49: 1, 52: 2, 53: 1, 57: 1
(Brilliant Carmine 6B), 60: 1, 63: 1, 63: 2, 64:
1, 81 (Rotamin 6G rake), 83, 88, 101 (Bengara), 104, 105, 106, 108 (Cadmium let), 112, 114, 122 (Kinacridon magenta), 12
3, 146, 149, 166, 168, 170, 17
2, 177, 178, 179, 185, 190, 19
3, 209, 219, C.I. I. Pigmen Violet 1 (Rotamine Lake), 3,
5: 1, 16, 19 (quinacridlet), 23, 38, C.I. I. Pigment Blue 1, 2, 15 (Phthalocyanine Blue
R), 15: 1, 15: 2, 15: 3 (phthalocyanine blue G), 1
5: 4, 15: 6 (phthalocyanine blue E), 16, 17: 1, 5
6, 60, 63, C.I. I. Pigment Green 1, 4, 7, 8, 10, 1
In addition, processed pigments such as graft carbon having a pigment surface treated with a resin or the like can be used. The addition amount thereof is preferably 0.5 to 30% by weight, more preferably 1.0 to 12% by weight. The particle size can be 25 μm or less, but it is preferable to use a pigment composed of particles having an average particle size of 1 μm or less, and further preferably an average particle size of 0.5 μm or less.

In order to uniformly disperse these coloring agents, if necessary, the dispersing agent is added in an amount of 0.5 to 200 wt.
% Can be added, and more preferably 1 to 50 wt.
%, Particularly preferably 10 to 30% by weight, and it is desirable to carry out dispersion treatment with a ball mill or the like.

As the water-soluble dye used in the present ink, a direct dye, an acid dye, a basic dye, an edible dye and the like are used. I. Direct Black 9, 17, 19, 22, 3
2, 51, 56, 62, 69, 77, 80, 91, 9
4, 97, 108, 112, 113, 114, 117,
118, 121, 122, 125, 132, 146, 1
54, 166, 168, 173, 199, C.I. I. Direct Red 2, 4, 9, 23, 26, 3
1, 39, 62, 63, 72, 75, 76, 79, 8
0, 81, 83, 84, 89, 92, 95, 111, 1
73, 184, 207, 211, 212, 214, 21
8, 221, 223, 224, 225, 226, 22
7, 232, 233, 240, 241, 242, 24
3, 247, C.I. I. Direct violet 7, 9, 47, 48,
51, 66, 90, 93, 94, 95, 98, 100,
101, C.I. I. Direct Yellow 8, 9, 11, 12, 2
7, 28, 29, 33, 35, 39, 41, 44, 5
0, 53, 58, 59, 68, 86, 87, 93, 9
5, 96, 98, 100, 106, 108, 109, 1
10, 130, 132, 142, 144, 161, 16
3, C.I. I. Direct Blue 1, 10, 15, 22, 2
5, 55, 67, 68, 71, 76, 77, 78, 8
0, 84, 86, 87, 90, 98, 106, 108,
109, 151, 156, 158, 159, 160, 1
68, 189, 192, 193, 194, 199, 20
0, 201, 202, 203, 207, 211, 21
3, 214, 218, 225, 229, 236, 23
7, 244, 248, 249, 251, 252, 26
4, 270, 280, 288, 289, 291, C.I. I. Acid Black 7, 24, 29, 48, 5
2: 1, 172, C.I. I. Acid Red 35, 42, 52, 57, 6
2, 80, 82, 111, 114, 118, 119, 1
27, 128, 131, 143, 151, 154, 15
8, 249, 254, 257, 261, 263, 26
6, 289, 299, 301, 305, 336, 33
7, 361, 396, 397, C.I. I. Acid Violet 5, 34, 43, 47,
48, 90, 103, 126, C.I. I. Acid Yellow 17, 19, 23, 25, 3
9, 40, 42, 44, 49, 50, 61, 64, 7
6, 79, 110, 127, 135, 143, 151,
159, 169, 174, 190, 195, 196, 1
97, 199, 218, 219, 222, 227, C.I. I. Acid Blue 9, 25, 40, 41, 62,
72, 76, 78, 80, 82, 92, 106, 11
2, 113, 120, 127: 1, 129, 138, 1
43, 175, 181, 205, 207, 220, 22
1, 230, 232, 247, 258, 260, 26
4, 271, 277, 278, 279, 280, 28
8, 290, 326, C.I. I. Basic Black 8, C.I. I. Basic Red 12, 13, 14, 15, 1
8, 22, 23, 24, 25, 27, 29, 35, 3
6, 38, 39, 45, 46, C.I. I. Basic Violet 1, 2, 3, 7, 1
0, 15, 16, 20, 21, 25, 27, 28, 3
5, 37, 39, 40, 48, C.I. I. Basic Yellow 1, 2, 4, 11, 13,
14, 15, 19, 21, 23, 24, 25, 28, 2
9, 32, 36, 39, 40, C.I. I. Basic Blue 1, 3, 5, 7, 9, 22,
26, 41, 45, 46, 47, 54, 57, 60, 6
2, 65, 66, 69, 71, C.I. I. Disperse Yellow 3, 5, 56, 60, 6
4, 160 C.I. I. Day Super Red 4, 5, 60, 72, 7
3, 91, C.I. I. Desperce Blue 3, 7, 56, 60, 7
9, 198 C.I. I. Desperse Orange 13, 30, C.I. I. Food black and the like are used, but not limited to these.

Examples of the water-insoluble dye which is used by being dispersed in the present ink or being mixed or dissolved in a resin include C.I. I. Solvent Black 3, 5, 22, C.I. I. Solvent Yellow 19, 44, 98, 104,
105, 112, 113, 114 C.I. I. Solvent Red 8, 24, 71, 109, 1
52, 155, 176, 177, 179 C.I. I. Solvent Blue 2, 11, 25, 78, 9
4, 95, C.I. I. Solvent Green 26, C.I. I. Solvent Orange 5, 40, 45, 72, 6
3, 68, 78 C.I. I. Solvent Violet 13, 31, 32, 3
However, the present invention is not limited to these.

The amount of these dyes to be added is determined depending on the type of dye, the type of solvent component, the properties required for the ink, etc., but is generally 0.2 with respect to the total weight of the ink.
The range of 10 to 10% by weight, preferably 0.5 to 5% by weight is good.

As the resin emulsion used in the present ink, one having an MFT of 50 ° C. or higher is used, preferably 60 to 90 ° C. is used.
A mixture of two or more species can be used.

The amount of the resin added in the resin emulsion is preferably 15% or more based on the total solids in the ink in order to obtain the above-mentioned good transferability and fastness. If it is less than 15%, a sufficient resin emulsion film-forming effect cannot be obtained. In order to firmly bind the colorant, the solid content ratio of the colorant to the resin emulsion is preferably in the range of 1: 1 to 1:20. However, since the reliability of the ink decreases as the added amount increases, it is preferable to suppress the added amount to about 30% by weight in terms of solid content with respect to the entire ink.

Examples of the resin emulsion include polyacrylic acid ester, polymethacrylic acid ester, polyethyl acrylic acid ester, styrene-butadiene copolymer, butadiene copolymer, acrylonitrile-butadiene copolymer, chloroprene copolymer, Crosslinked acrylic resin, crosslinked styrene resin, fluororesin, vinylidene fluoride, benzoguanamine resin, phenol resin, polyolefin resin, styrene-acrylic acid ester copolymer,
Styrene-methacrylic acid ester copolymer, polystyrene, styrene-acrylamide copolymer, n-isobutyl acrylate, acrylonitrile, vinyl acetate, acrylamide, silicone resin, polyvinyl acetal, rosin resin, polyethylene, polycarbonate,
Vinylidene chloride resin, epoxy resin, vinyl acetate resin,
Examples thereof include, but are not limited to, ethylene-vinyl acetate copolymer, vinyl acetate-acrylic copolymer, vinyl chloride resin, and polyurethane.

The low molecular weight resin emulsion that can be used in the present ink includes the following. For example, polyethylene wax, montan wax, alcohol wax, synthetic oxidation wax, α-olefin-maleic anhydride copolymer, animal / vegetable wax such as carnauba wax, lanolin, paraffin wax, microcrystalline wax, etc. can be transferred onto the recording medium. It can be used as long as it is excellent in toughness when exposed.

Water-soluble polymers can be mixed in order to increase the tackiness of the ink and improve the transferability.

As the water-soluble polymer which can be used in the present ink, polyalkyl oxide such as polyethylene oxide, polyvinyl pyrrolidone, polyvinyl alcohol, polyvinyl butyral, polyacrylic acid, glue, gelatin, casein, albumin, gum arabic,
Alginic acid, methyl cellulose, carboxymethyl cellulose, hydroxyethyl cellulose, polyvinyl ether, polyvinyl methyl ether, polyethylene glycol, and further monosaccharides such as glucose, xylose, sucrose, maltose, arabinose, α-cyclodextrin, starch, disaccharides, polysaccharides, Examples include glycosides.

If necessary, the surface tension of the ink is reduced to improve the wettability to a transfer medium made of a rubber material having a low surface tension, so that the ink is repelled on the ink image transfer medium.
One or more water-soluble anionic, cationic, amphoteric or nonionic surfactants can be added to prevent flow and fix the ink image.

The amount of addition is 0.05 to 10 wt%, preferably 0.1 to 8 wt% to ensure sufficient wettability.
is necessary.

For example, as the anionic surfactant, higher fatty acid salt, higher alkyl dicarboxylic acid salt, higher alcohol sulfate ester salt, higher alkyl sulfonate, alkylbenzene sulfonate, alkylnaphthalene sulfonate, naphthalene sulfonic acid salt ( Na, K, Li, C
a) Formalin polycondensate, condensate of higher fatty acid and amino acid, dialkylsulfosuccinic acid ester salt, alkylsulfosuccinate, naphthenate, etc., alkyl ether carboxylate, acylated peptide, α-olefin sulfonate, N- Acyl methyl taurine, alkyl ether sulfate, secondary higher alcohol ethoxy sulfate,
Polyoxyethylene alkyl phenyl ether sulfate,
Examples thereof include, but are not limited to, monoglycerate, alkyl ether phosphate ester salt, and alkyl phosphate ester salt.

Examples of the cationic surfactant include, but are not limited to, aliphatic amine salt, quaternary ammonium salt, sulfonium salt and phosphonium salt.

Amphoteric surfactants include, but are not limited to, carboxybetaine type, aminocarboxylic acid salts, lecithin and the like.

Fluorine-based nonionic surfactants,
Silicone type, acrylic acid copolymer, polyoxyethylene alkyl ether, polyoxyethylene alkylphenyl ether, polyoxyethylene secondary alcohol ether, polyoxyethylene sterol ether, polyoxyethylene lanolin derivative, ethylene oxide derivative of alkylphenol formalin condensate , Polyoxyethylene polyoxypropylene block polymer, polyoxyethylene polyoxypropylene alkyl ether, polyoxyethylene compound fatty acid ester type, polyethylene oxide condensation type polyethylene glycol fatty acid ester, fatty acid monoglyceride, polyglycerin fatty acid ester, sorbitan fatty acid ester, propylene glycol Fatty acid ester, sucrose fatty acid ester, fatty acid alkanolamide, Polyoxyethylene fatty acid amides, polyoxyethylene alkyl amines, do not there are alkylamine oxides being limited thereto.

In addition, if necessary, a pH adjusting agent such as potassium dihydrogen phosphate or disodium hydrogen phosphate, an antifungal agent,
Benzoic acid, dichlorophen, hexachlorophene, sorbic acid, p-hydroxybenzoic acid ester, ethylenediaminetetraacetic acid (EDTA), sodium dehydroacetate, 1,2-bezothiazolin-3-one (product name) for the purpose of antiseptic and rust prevention. : Proxel XLII (manufactured by ICI)), 3, 4
-Isothiazolin-3-one and the like can be included. Further, urea, thiourea, ethylene urea and the like can be added for the purpose of preventing nozzle drying.

The physical properties of the ink are 50 in order to ensure stable ejection from the head and stable ink supply to the head.
It is preferably mPa · sec or less, and more preferably 25 mPa · sec or less. Each of the ink composition examples described below was adjusted to have a viscosity within this range.

Table 2 shows examples of ink compositions that can be used in the inkjet recording method of the present invention. The numerical values of the composition ratios are all% by weight. In addition, the resin emulsion shows the addition amount of the resin component.

Further, as shown in Table 2, the ratio of the resin content to the total solid content (excluding the surfactant and the preservative) of the ink of this example is 15% or more.

[0074]

[Table 2]

Table 2 shows the composition of the ink as a comparative example.

Ink Comparative Example 1 is described in US Pat. No. 4,538,815.
It is a composition example produced based on the conventional example described in the specification of No. 6.

In the ink comparative example 2, the resin emulsion of the ink composition 2 was replaced with a resin emulsion having an MFT of less than 50 ° C. The ink was manufactured in the same manner as in Ink Example 1.

As Comparative Example 1 of the present invention, a transfer type ink jet printer having the structure shown in FIG. 1 was used, and a recording method in which the surface temperature of the transfer medium was lower than 50 ° C. was used.

As Comparative Example 2 of the present invention, a transfer type ink jet printer having the structure shown in FIG. 1 was used, and a recording method in which the surface temperature of the transfer medium exceeded 150 ° C. was used.

The results of printing tests using the above inks in the examples and comparative examples of the transfer type ink jet recording method of the present invention are shown below.

The evaluation items are 1. 2. Relationship between transfer pressure and transfer efficiency when transferring an ink image, 2 nozzle clogging, and printed matter robustness. Water resistance was evaluated for three items.

The evaluation conditions and criteria are as follows.

1. Relationship between transfer pressure and transfer efficiency Time from printing to transfer Printing start part: 10 seconds Printing end part: 2 seconds Printing pattern solid 1 dot continuous line, transfer pressure 0.6 kg weight / cm: Equipment miniaturization, parts cost reduction Easy 1.0 kg weight / cm: Device downsizing and cost reduction of parts are possible 1.5 kg weight / cm: Device downsizing and cost reduction of parts are difficult Transfer efficiency ○: Transfer efficiency is 100% and transfer remains without image deformation B: Image transfer occurs due to partial transfer remaining at a transfer efficiency of 95 to 100%. X: Clear density change, white spots at a transfer efficiency of less than 95%.
Image deformation occurs 2. Nozzle clogging property ◯: No clogging after leaving for 5 minutes Δ: 〃 Partial clogging has occurred ×: 〃 All nozzles are clogged Water resistance (1 minute after printing) ◯: The printed matter does not bleed at all even if water drips on the printed matter. Δ: Edges are blurred when water drips on the printed matter. X: Water drips on the printed matter. Based on the above evaluation conditions and judgment criteria, ink composition 1 to
Table 3 shows the results of investigations on the recording methods of Examples and Comparative Examples using No. 3, Ink Comparative Examples 1 and 2.

[0084]

[Table 3]

As shown in the above table, according to the recording method of the present invention, when the solvent component of the ink image on the transfer medium is evaporated by the heating means, the surface temperature of the transfer medium is changed to that of the resin emulsion contained in the ink. By setting the MFT or more, it was possible to transfer the ink image obtained on the transfer medium onto the recording medium without being affected by the time from printing to transfer or the print pattern.

Further, the nozzle clogging of the recording head can be secured under the use environment of less than 50 ° C., the transfer medium surface temperature is 50 ° C. or higher, and the MF of the resin emulsion is MF.
By setting it to be T or more, the robustness of the recorded image was obtained, and it was possible to secure both the clogging property and the robustness.

On the other hand, when the ink comparative example using the water-soluble dye containing no conventional resin emulsion was used, the clogging property was good, but the transfer efficiency and the water resistance were insufficient. Further, when an ink comparative example having an MFT of less than 50 ° C. was used, the water resistance was good, but the transfer efficiency and the clogging property were insufficient.

In Comparative Example 1 of the recording method in which the surface temperature of the transfer medium is less than 50 ° C. as a comparative example of the recording method, the clogging property was good for all inks, but the transfer efficiency and water resistance were poor. Was enough. Furthermore, as a comparative example of the recording method, Comparative Example 2 of the recording method in which the surface temperature of the transfer medium exceeds 150 ° C. had good water resistance, but the transfer efficiency and the clogging property were insufficient regardless of the ink. It was

The above results indicate that the recording method of the present invention contains the resin emulsion having an MFT of 50 ° C. or more in the ink and heats the surface temperature of the transfer medium to the MFT of the resin emulsion contained in the ink or more. Since the water in the ink image is evaporated and a film with uniform strength and adhesiveness is obtained, the ink obtained on the transfer medium at a low pressure regardless of the time from printing to transfer or the print pattern. The image is obtained by a new effect that an image can be transferred to a recording medium, and that the nozzle clogging of the recording head can be prevented and the robustness of the ink image transferred onto the recording medium can be secured at the same time.

The present invention can be applied to a two-color printer, a multi-color printer, and a full-color printer because it is possible to overlay a plurality of inks on a transfer medium.

[0091]

EFFECTS OF THE INVENTION According to the present invention, the ink contained in the ink contains a resin emulsion having an MFT of 50 ° C. or more, and the surface temperature of the transfer medium is heated to the MFT of the resin emulsion contained in the ink or more, whereby the water content in the ink image is increased. The ink image obtained on the transfer medium is transferred to the recording medium at a low pressure regardless of the time from printing to transfer or the print pattern, because a film with uniform strength and adhesiveness is obtained. It has the novel effect of being able to. Further, the surface temperature of the transfer medium is sufficiently higher than the environmental temperature of use, and a temperature range (50 ° C. to 150 ° C.) that can prevent rapid evaporation of the solvent component in the ink
C.) has the novel effect that both the prevention of nozzle clogging of the recording head and the securing of the robustness of the ink image transferred onto the recording medium can be achieved at the same time.

[Brief description of drawings]

FIG. 1 is a perspective view showing a configuration of an inkjet printer according to an embodiment of the present invention.

FIG. 2 is a sectional view showing a configuration of an inkjet printer according to an embodiment of the present invention.

FIG. 3 is a diagram showing how an ink image is written by a recording head used in an example of the present invention.

FIG. 4 is a perspective view showing another ink image writing process applicable to the present invention.

FIG. 5 is a perspective view showing still another ink image writing step applicable to the present invention.

FIG. 6 is a cross-sectional view showing the structure of another transfer medium applicable to the present invention.

[Explanation of symbols]

 1: Transfer drum (transfer medium) 2: Recording head 3: Backup roller (transfer means) 5: Ink image 6: Recording paper (recording medium) 7: Heating means

Claims (2)

[Claims] 1. An ink containing at least water, a colorant, and a resin emulsion having a minimum film-forming temperature of 50 ° C. or higher is ejected as an ink droplet from a recording head, and the surface temperature is made to be the minimum image film temperature of the resin emulsion or higher. It is characterized in that it includes a step of writing an ink image on a heated transfer medium, a step of evaporating a solvent component of the ink image on the transfer medium, and a transfer step of transferring the ink image on the transfer medium to a recording medium. Inkjet recording method. 2. The ink jet recording method according to claim 1, wherein in the step of concentrating the ink image, the surface temperature of the heated transfer medium is 50 ° C. to 150 ° C. or lower.