JP7467859B2 - Image forming device - Google Patents

Description

The present invention relates to an image forming device.

Inkjet printers have the advantages of being quiet, having low running costs, and being easy to print in color, and are widely used in ordinary households as digital signal output devices.

In recent years, an inkjet recording method has been disclosed that is capable of printing not only on household items, but also on fabrics such as woven fabrics and knitted fabrics (Patent Document 1).

In the so-called DTG (Direct to Garment) field, where printing is done directly on clothing such as T-shirts, there has been a rapid increase in demand for sportswear in addition to the conventional cotton and cotton-polyester blend media, and compatibility with polyester media is required. This trend is not only seen in the DTG field, but in the entire textile printing field, and even in inkjet printing machines equipped with a winding/unwinding mechanism, there is an ever-increasing demand for inkjet recording systems that can form images with excellent color development and various fastness properties on fabrics of various materials including cotton and polyester.

For example, there is disclosed a method in which a pretreatment liquid is applied to the fabric before printing the ink onto the fabric, thereby causing the ink to remain on the surface of the fabric (Patent Document 2), and a method in which the ink viscosity and the fabric transport speed are controlled according to the thickness of the fabric, thereby causing the ink to remain on the surface of the fabric (Patent Document 3).

However, while the conventional inkjet recording method disclosed in Patent Document 1 achieves color development in natural fibers at a level acceptable to the market, there is a problem in that the ink penetrates into the interior of fabrics containing synthetic fibers, resulting in a significant deterioration in color development.
Furthermore, when either of the means disclosed in Patent Document 1 or Patent Document 2 is used, there is a problem in that when the ink lands on a fabric whose main component is a synthetic fiber such as polyester or nylon, the ink does not easily wet and spread over the fiber, resulting in uneven image density.

Therefore, there is a need to develop a printing method that achieves both high image density and suppression of image density unevenness for fabrics made from different fiber types, namely natural and synthetic fibers.

In view of the above situation, the present invention aims to provide an image forming device that can produce images with high color development and minimal unevenness in image density for both fabrics whose main components are natural fibers and fabrics whose main components are synthetic fibers.

The above problem is solved by the following configuration 1).
1) A printing apparatus comprising: an ink having a dynamic surface tension of 30 mN/m or more and 50 mN/m or less with a life time of 15 ms at 25° C.; and a head for ejecting the ink onto a fabric;
the head includes a nozzle surface on which nozzles for ejecting the ink are formed and which faces the fabric;
An image forming apparatus characterized in that, when the ink is ejected from the nozzle onto a fabric primarily composed of natural fibers, the distance between the nozzle surface and the fabric is shorter than the distance between the nozzle surface and the fabric primarily composed of natural fibers and to which a pretreatment liquid containing a coagulant is applied and when the ink is ejected from the nozzle onto the fabric primarily composed of synthetic fibers.

The present invention provides an image forming device that can produce images with high color development and minimal unevenness in image density for both fabrics whose main components are natural fibers and fabrics whose main components are synthetic fibers.

1 is a schematic cross-sectional view of an embodiment of an image forming apparatus according to the present invention, taken along a direction perpendicular to a transport direction. 1 is a schematic plan view of an embodiment of an image forming apparatus of the present invention. FIG. 4 is a schematic plan view of another embodiment of the image forming apparatus of the present invention. 1 is a schematic side view of an embodiment of an image forming apparatus of the present invention. FIG. 4 is a schematic side view of the image forming apparatus according to another embodiment of the present invention. FIG. 4 is a schematic plan view of another embodiment of the image forming apparatus of the present invention. 1 is a schematic diagram of a main portion of an image forming apparatus according to an embodiment of the present invention; FIG. 4 is a schematic diagram of another main part of the image forming apparatus according to the embodiment of the present invention. FIG. 2 is a flow diagram of image formation according to an embodiment of the present invention.

The following describes the embodiments of the present invention in more detail.

In fabrics made primarily of synthetic fibers, the gaps between the fibers are larger than in fabrics made primarily of natural fibers due to the characteristics of the fibers, making it easier for ink to penetrate into the fabric, and the ink that lands on the fibers does not wet easily. Therefore, in fabrics made primarily of synthetic fibers, the fibers on the surface of the fabric cannot be covered with pigment, and if ink is applied using the same recording mode as for fabrics made primarily of natural fibers, the image density will decrease or become uneven.

In this invention, the distance between the head and the fabric in a fabric mainly made of synthetic fibers is made shorter than the distance between the head and the fabric in a fabric mainly made of natural fibers. This improves the accuracy of the landing position on the fabric, even in a fabric mainly made of synthetic fibers, and allows the ink to land more densely, accurately and evenly, thereby suppressing uneven image density. The larger the distance (gap) between the head and the fabric, the lower the landing accuracy, and the ink may not land at the target position. Synthetic fibers have high ink permeability and are prone to density loss and uneven density, so image quality cannot be achieved unless the droplets land densely and evenly.

Furthermore, by using ink with a dynamic surface tension of 50 mN/m or less with a life time of 15 ms at 25°C, it is possible to promote the wetting and spreading of the ink on the fibers, even in fabrics whose main component is synthetic fiber, and to suppress unevenness in image density even on recording media such as fabrics, which have large irregularities and are prone to variations in the ink landing position. Also, by setting the dynamic surface tension to 30 mN/m or more with a life time of 15 ms at 25°C, it is possible to suppress the ink from penetrating into the interior of fabrics, even in fabrics whose main component is natural fiber, and to maintain high image density.

In this embodiment, the distance between the nozzle surface and the fabric when the ink is ejected onto a fabric mainly made of synthetic fibers is shorter than the distance between the nozzle surface and the fabric when the ink is ejected onto a fabric mainly made of natural fibers. To achieve this, appropriate modifications can be made, but for example, a first recording mode for recording onto a fabric mainly made of natural fibers and a second recording mode for recording onto a fabric mainly made of synthetic fibers are provided.

Below, an example configuration having a first recording mode and a second recording mode will be described. In the first recording mode, ink is ejected onto a fabric whose main component is natural fibers, and in the second recording mode, ink is ejected onto a fabric whose main component is synthetic fibers. In this embodiment, the distance between the head and the fabric in the second recording mode is shorter than the distance between the head and the fabric in the first recording mode. Note that, unless otherwise specified, "distance between the head and the fabric" means the distance between the nozzle surface of the head and the fabric, and the nozzle surface is the surface of the head on which the nozzles are formed.

When the distance between the head and the fabric in the second recording mode is 1 mm or more shorter than the distance between the head and the fabric in the first recording mode, it is more suitable for suppressing uneven image density.

When the distance between the head and the fabric in the first and second recording modes is 0.5 mm or more and 5 mm or less, this is favorable for improving ejection reliability and suppressing uneven image density.

When the landing distance between droplets successively ejected from the head in the second recording mode is shorter than the landing distance between droplets successively ejected from the head in the first recording mode, the ink lands more easily on the fibers of the surface layer of the fabric in a fabric primarily composed of synthetic fibers than in a fabric primarily composed of natural fibers, improving image density. In addition, by shortening the interval between droplets, the ink is less susceptible to the effects of variations in the landing position of the ink, even in fabric primarily composed of synthetic fibers, which are less susceptible to ink spreading, making it suitable for suppressing uneven image density.

When the landing distance between droplets successively ejected from the head in the second recording mode is 10 μm or more shorter than the landing distance between droplets successively ejected from the head in the first recording mode, it is more suitable for suppressing uneven image density.

When the landing distance between ink droplets successively ejected from the head in the first recording mode and the second recording mode is 10 μm or more and 100 μm or less, sufficient image sharpness can be obtained even for fabrics with different unevenness due to the weaving or knitting method, which is preferable.

By making the size of ink droplets ejected from the head on a fabric primarily composed of synthetic fibers larger than the size of ink droplets ejected from the head on a fabric primarily composed of natural fibers, the ejected ink droplets are more likely to catch on the fibers on the surface of the fabric, even on fabric primarily composed of synthetic fibers, improving image density. Therefore, when the size of ink droplets ejected in the second recording mode is larger than the size of ink droplets ejected in the first recording mode, it is more suitable for suppressing uneven image density.

When the droplet size of the ink ejected in the second recording mode is at least 3 pL larger per droplet than the droplet size of the ink ejected in the first recording mode, it is more suitable for improving image density.

When the droplet size of the ink ejected in the first recording mode and the second recording mode is 5 pL or more and 30 pL or less in volume per droplet, sufficient image density and sharpness can be obtained even on fabrics with high ink absorbency, which is preferable.

When the ink has a dynamic surface tension of 32 mN/m or more and 45 mN/m or less at 25°C with a life time of 15 ms, it is suitable not only for improving the image density of fabrics whose main component is natural fibers, but also for suppressing uneven image density of fabrics whose main component is synthetic fibers.

<Fabrics made primarily from natural fibers>
In the present invention, the fabric mainly composed of natural fibers refers to a fabric containing natural fibers in a mass ratio of 50% or more. The types of natural fibers include, but are not limited to, cotton, linen, silk, wool, etc.

<Fabrics made primarily of synthetic fibers>
In the present invention, the fabric mainly composed of synthetic fibers refers to a fabric containing synthetic fibers in a mass ratio of more than 50%. The types of synthetic fibers include, but are not limited to, polyester, nylon, rayon, etc.

The fabric mainly composed of natural fibers has a basis weight of, for example, 80 to 250 g/ ^m2 , and preferably 100 to 220 g/ ^m2 .
The fabric mainly composed of synthetic fibers has a basis weight of, for example, 60 to 230 g/ ^m2 , and preferably 80 to 200 g/ ^m2 .

A first embodiment of the present invention will be described.
The recording modes of the image forming apparatus of this embodiment include at least a first recording mode for recording on a fabric mainly composed of natural fibers, and a second recording mode for recording on a fabric mainly composed of synthetic fibers. The image forming apparatus is capable of switching between the first recording mode and the second recording mode.

A default value for the recording mode is set in the image forming device, and the default setting value may be set to either the first recording mode or the second recording mode, but the following explanation uses an example in which the first recording mode is set as the default value.

The first recording mode and the second recording mode are switched according to the composition (type, ingredients, etc.) of the recording medium (fabric) to be printed. The composition of the fabric may be detected by a detection means for detecting the composition of the fabric within the image forming device, or the composition of the fabric to be used may be input by a person or input using a recording medium type selection button that is set in the device beforehand. Also, instead of inputting the composition of the fabric, the first recording mode or the second recording mode may be directly selected. The image forming device may be equipped with an input unit such as a touch panel, and the type of fabric, ingredients of the fabric, etc. may be input by the input unit.

In this embodiment, when the second recording mode is selected on the recording mode selection screen, the distance between the head and the fabric, which is the recording medium, is shortened. In this case, a known method can be used to change the distance between the head and the recording medium. Means such as raising the platen that holds the recording medium or lowering the carriage equipped with the head can be used.

The distance between the head and the recording medium is found by measuring the distance between the nozzle face of the head and the surface of the recording medium on the nozzle face side. Alternatively, an initial value for the distance between the head and the platen may be stored and found based on the thickness of the recording medium, the distance the platen is raised, the distance the carriage is lowered, etc. In this embodiment, the distance between the nozzle face and the recording medium is linked to the distance between the nozzle face and the platen, and if the distance between the nozzle face and the recording medium is shortened, the distance between the nozzle face and the platen also becomes shorter. Also, if the distance between the nozzle face and the recording medium is longer, the distance between the nozzle face and the platen also becomes longer.

Next, a second embodiment of the present invention will be described.
In the second embodiment, when the second recording mode is selected, the landing distance between successive ink droplets ejected from the head onto the fabric is changed so as to become closer.
The inter-drop landing distance is the distance between the centers of adjacent ink dots.
Making the landing distance between the droplets closer means, in other words, changing the settings so as to shorten the distance between the positions of adjacent ink dots. In this case, the landing distance can be changed using a known method, such as changing the drive frequency of the head, slowing down the scanning speed of the carriage equipped with the head, or reducing the feed amount of the recording medium.

Next, a third embodiment of the present invention will be described.
In the third embodiment, when the second recording mode is selected, the setting is changed so that the ejection speed of the ink ejected from the head onto the fabric is slowed down. In this case, the ejection speed can be changed by a known method, such as changing the drive frequency of the head or changing the voltage applied to the piezoelectric body.
According to the third embodiment, an image with high color development and little unevenness in image density can be obtained even for fabrics whose main component is synthetic fiber.

Next, a fourth embodiment of the present invention will be described.
In the fourth embodiment, when the second recording mode is selected, the size of the ink droplets ejected from the head onto the fabric is changed to be larger than the size of the ink droplets in the first recording mode. In this case, a known method can be used to change the droplet size. For example, when the head is a piezo type, the voltage applied to the piezo can be increased, the amount of retraction of the piezo can be increased, the ink can be merged, etc. Even when a thermal type head is used, a known method can be used.

The size of ink droplets is measured by taking pictures of the droplets from multiple directions just before they hit the fabric and calculating the volume. For ink droplets that coalesce, the droplets are photographed after coalescence and then measured.
The following method can also be used to measure the size of ink droplets. First, an image is printed onto a non-permeable medium such as film or onto silicone oil, and the change in weight is measured before and after printing the image. Then, the weight is divided by the number of droplets ejected to convert to the weight per droplet. The ink density is then measured, and the ink droplets are treated as spheres, and the diameter of each droplet is estimated using the formula for the volume of a sphere, thereby obtaining the droplet size.

Next, a specific example of the image forming apparatus of the present invention is shown in FIG. 1. In FIG. 1, the recording medium is transported in the depth direction (or forward direction) of the paper surface, and FIG. 1 is a schematic cross-sectional view in a direction perpendicular to the transport direction of the recording medium.

In FIG. 1, the carriage 10, the first head 11, the second head 12, the carriage scanning rail 13, the exhaust section 14, the platen 15 (fabric holding member), the support member 16, the platen moving table 17, and the maintenance unit 18 are shown.

The platen 15 is a member that holds the recording medium, and the size, etc. can be changed as appropriate. The platen 15 is supported by a support member 16. In this embodiment, the platen 15 has a lifting function and can be raised and lowered in the direction (B) in the figure. This makes it possible to change the distance between the nozzle surface and the platen and the distance between the nozzle surface and the recording medium.

The platen moving platform 17 is a mechanism for moving the platen 15, and can move the platen 15 vertically (in the direction of the arrow (B) in the figure), and can also move it in the direction in which the recording medium is transported.

The maintenance unit 18 is a mechanism for maintaining the head, and is made up of a cap, a suction pump, an empty discharge receiver, etc.

The carriage 10 is a housing that has a first head 11 and a second head 12, and in addition to the heads, also includes an encoder sensor, a moving belt, a lifting mechanism, etc. The lifting mechanism allows the carriage 10 to rise and fall in the direction (B) in the figure, which makes it possible to change the distance between the nozzle surface and the platen and the distance between the nozzle surface and the recording medium.
The carriage scanning rail 13 is a rail for moving the carriage 10 in a direction perpendicular to the conveying direction of the recording medium.

The direction perpendicular to the transport direction of the recording medium is sometimes called the main scanning direction, and the main scanning direction is indicated by the arrow (A) in the figure. The transport direction of the recording medium is sometimes called the sub-scanning direction, and the main scanning direction and the sub-scanning direction are perpendicular to each other.

The first head 11 is a head that ejects a pretreatment liquid, and is provided as necessary. The second head is a head that ejects the ink used in the present invention. The first head 11 is provided upstream of the second head in the transport direction of the recording medium. Note that when the first head 11 and the second head 12 are described without distinction, they may be simply referred to as heads.

The exhaust unit 14 is a mechanism for exhausting gas from the device body 22 to the outside of the device body 22. For example, it may have a fan, such as a fan connected to a motor.

FIG. 2 is a schematic plan view of the image forming apparatus of this embodiment, showing the carriage 10 and the platen 15 before they move.
As shown in the figure, a carriage 10 includes a first head 11 and a second head 12. Note that the carriage scanning rail 13 is omitted in FIG.
In addition, the platen 15 moves along a platen movement rail 19 .

FIG. 3 is another schematic plan view of the image forming apparatus of this embodiment, showing a state when the carriage 10 and the platen 15 in FIG. 2 have moved.
As shown in the figure, the platen 15 moves along a platen movement rail 19 in the direction of the arrow indicated by (C) in the figure. Since the recording medium is held on the platen 15 and moves, the movement direction of the platen 15 and the transport direction of the recording medium coincide with each other.
As shown in the figure, the second head 12 is disposed downstream of the first head 11 in the transport direction of the recording medium.

When the platen 15 moves in the direction of the arrow indicated by (C) in the figure and approaches the carriage 10, liquid is ejected from the head while the carriage 10 scans in the main scanning direction (direction (A) in the figure). At this time, pretreatment liquid is ejected first from the first head 11 toward the recording medium, and then ink is ejected from the second head 12 toward the recording medium.

FIG. 4 is a schematic side view of the image forming apparatus of this embodiment, and FIG. 5 is an enlarged schematic view of a main portion of FIG.
The exhaust unit 14 in this embodiment is preferably disposed so that the gas between the first head 11 and the platen 15 (or the recording medium) flows upstream in the conveying direction of the recording medium. Also, as shown by the arrow (D) in Fig. 4, the gas inside the device body 22 is exhausted to the outside.

As a result, as shown in FIG. 5, the flow direction in the space between the platen 15 and each head is from the second head 12 toward the first head 11 (the direction of the arrow indicated by (D) in FIG. 5). In other words, the gas between the first head 11 and the platen 15 (or the recording medium) flows upstream in the transport direction of the recording medium.

As a result, the pretreatment liquid mist generated near the first head 11 is less likely to reach the second head 12, and the pretreatment liquid mist can be prevented from adhering to the nozzle formation surface of the second head 12 and causing the ink to aggregate. Furthermore, by preventing the ink from aggregation, ejection reliability is improved.

As shown in FIG. 5, the flow in the space between the second head 12 and the platen 15 (or the recording medium) may also flow upstream in the recording medium transport direction.

Another schematic plan view of this embodiment is shown in Fig. 6. Fig. 6 illustrates the gas flow (D) in the plan view of Fig. 3.
As shown in the drawing, the liquid ejecting device of this embodiment is provided with a plurality of exhaust units 14. In this embodiment, the plurality of exhaust units 14 are all disposed upstream of the first head 11 in the conveying direction of the recording medium ((C) in the drawing).
This causes the gas to be exhausted upstream in the conveying direction of the recording medium, thereby achieving the above-mentioned effects.

The position of the recording medium may be fixed, and the carriage may be transported upstream and downstream. In this case, "upstream and downstream in the transport direction of the recording medium" in this embodiment may be considered as the transport direction relative to the head. In other words, the upstream side in the transport direction of the recording medium corresponds to the downstream side in the transport direction of the head, and the downstream side in the transport direction of the recording medium corresponds to the upstream side in the transport direction of the head.

Next, FIG. 7 shows a schematic diagram of the main parts of the image forming apparatus in this embodiment. FIG. 7 shows a first head 11 that ejects pretreatment liquid from a nozzle, a second head 12 that ejects ink from a nozzle, a platen 15 (fabric holding member) that holds the recording medium 30, and a heating means 40 that heats the recording medium 30.

The nozzle surface 11a of the first head 11 and the nozzle surface 12a of the second head 12 are also shown, with (a) indicating the distance between the nozzle surface 12a and the recording medium 30. Furthermore, (b) indicates the distance between the nozzle surface 12a and the platen 15. (a) in the figure may be referred to as the first gap distance, and (b) in the figure may be referred to as the second gap distance. The gap distance can be changed by the lifting and lowering functions of the platen and carriage, etc.

Figure 8 shows another schematic diagram of the main parts of the image forming apparatus in this embodiment. Figure 8 is a diagram similar to Figure 7. As shown in the figure, the fabric, which is the recording medium, may be wavy due to the characteristics of the fabric and material. In this case, the distance ((a) in the figure) between the highest part on the nozzle face 12a side and the nozzle face 12a is measured to obtain the first gap distance. Furthermore, the distance (a) is measured excluding the fuzzy parts. For example, the surface is smoothed with a pressing member or the like before measurement, and then measurement is performed.

It is preferable that the thickness of the recording medium is 3.5 mm or less. This prevents the effects of nap in the fabric, which can reduce the accuracy of impact, and the heated parts of the recording medium rising up and coming close to the nozzle, which can cause heat conduction to the nozzle and result in non-ejection.

As an example of the configuration of the image forming apparatus of this embodiment, the apparatus may have a head that ejects ink having a dynamic surface tension of 30 mN/m or more and 50 mN/m or less with a life time of 15 ms at 25°C. In this case, as in the above, the head has a nozzle surface, and the distance between the nozzle surface and the fabric when the ink is ejected onto a fabric mainly composed of synthetic fibers is shorter than the distance between the nozzle surface and the fabric when the ink is ejected onto a fabric mainly composed of natural fibers.

FIG. 9 is a flow diagram of image formation in this embodiment.
FIG. 9 shows an embodiment in which the type of fabric is determined based on fabric information inputted to an input unit of the image forming apparatus.
First, the fabric is set in the image forming apparatus (S100).
Next, it is determined whether the fabric is mainly composed of natural fibers or synthetic fibers based on the fabric information inputted to the input section (S101).
If the fabric is made of natural fibers, a first recording mode is selected (S102), the ink droplet size, landing distance and/or head-to-fabric distance are adjusted (S103), and ink is ejected onto the fabric to form an image (S104).
On the other hand, if the fabric is made of synthetic fibers, a second recording mode is selected (S105), the ink droplet size, landing distance and/or head-to-fabric distance are adjusted (S106), and ink is ejected onto the fabric to form an image (S107).

In the above example, the type of fabric is determined based on the fabric information input to the input unit of the image forming device, and the distance between the head and the fabric is changed, but this is not limited to the above, and the components of the fabric may be detected by a detection means. The composition of the fabric may be detected by a detection means provided in the image forming device, and the distance between the head and the fabric may be changed based on this. Such detection means are well known, and a person skilled in the art would be able to select an appropriate one.

Next, we will explain the ink used in the present invention.

<Ink>
The organic solvent, water, coloring material, resin, additives, etc. used in the ink will be described below.

<Organic Solvent>
The organic solvent used in the present invention is not particularly limited, and any water-soluble organic solvent can be used. Examples of the organic solvent include polyhydric alcohols, ethers such as polyhydric alcohol alkyl ethers and polyhydric alcohol aryl ethers, nitrogen-containing heterocyclic compounds, amides, amines, and sulfur-containing compounds.
Specific examples of the water-soluble organic solvent include ethylene glycol, diethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, 3-methyl-1,3-butanediol, triethylene glycol, polyethylene glycol, polypropylene glycol, 1,2-pentanediol, 1,3-pentanediol, 1,4-pentanediol, 2,4-pentanediol, 1,5-pentanediol, and the like. polyhydric alcohols such as pentanediol, 1,2-hexanediol, 1,6-hexanediol, 1,3-hexanediol, 2,5-hexanediol, 1,5-hexanediol, glycerin, 1,2,6-hexanetriol, 2-ethyl-1,3-hexanediol, ethyl-1,2,4-butanetriol, 1,2,3-butanetriol, 2,2,4-trimethyl-1,3-pentanediol, and petriol; ethylene glycol monoethyl ether; and ethylene glycol monobutyl ether. polyhydric alcohol alkyl ethers such as diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, tetraethylene glycol monomethyl ether, and propylene glycol monoethyl ether; polyhydric alcohol aryl ethers such as ethylene glycol monophenyl ether and ethylene glycol monobenzyl ether; nitrogen-containing heterocyclic compounds such as 2-pyrrolidone, N-methyl-2-pyrrolidone, N-hydroxyethyl-2-pyrrolidone, 1,3-dimethyl-2-imidazolidinone, ε-caprolactam, and γ-butyrolactone; amides such as formamide, N-methylformamide, N,N-dimethylformamide, 3-methoxy-N,N-dimethylpropionamide, and 3-butoxy-N,N-dimethylpropionamide; amines such as monoethanolamine, diethanolamine, and triethylamine; sulfur-containing compounds such as dimethyl sulfoxide, sulfolane, and thiodiethanol; propylene carbonate, and ethylene carbonate.
It is preferable to use an organic solvent having a boiling point of 250° C. or less, since this not only functions as a wetting agent but also provides good drying properties.

Polyol compounds having 8 or more carbon atoms and glycol ether compounds are also suitably used. Specific examples of polyol compounds having 8 or more carbon atoms include 2-ethyl-1,3-hexanediol and 2,2,4-trimethyl-1,3-pentanediol.
Specific examples of the glycol ether compound include polyhydric alcohol alkyl ethers such as ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, tetraethylene glycol monomethyl ether, and propylene glycol monoethyl ether; and polyhydric alcohol aryl ethers such as ethylene glycol monophenyl ether and ethylene glycol monobenzyl ether.

The content of the organic solvent in the ink is not particularly limited and can be selected appropriately depending on the purpose, but from the viewpoint of the drying property and ejection reliability of the ink, it is preferably 10% by mass or more and 60% by mass or less, and more preferably 20% by mass or more and 60% by mass or less.

<Water>
The water content in the ink is not particularly limited and can be appropriately selected depending on the purpose. From the viewpoints of the drying property and ejection reliability of the ink, however, the water content is preferably from 10% by mass to 90% by mass, and more preferably from 20% by mass to 60% by mass.

<Coloring material>
The coloring material is not particularly limited, and pigments and dyes can be used.
As the pigment, inorganic pigments or organic pigments can be used. These pigments can be used alone or in combination of two or more. Mixed crystals can also be used.
Examples of pigments that can be used include black pigments, yellow pigments, magenta pigments, cyan pigments, white pigments, green pigments, orange pigments, glossy pigments such as gold and silver pigments, and metallic pigments.
As inorganic pigments, titanium oxide, iron oxide, calcium carbonate, barium sulfate, aluminum hydroxide, barium yellow, cadmium red, chrome yellow, as well as carbon black produced by known methods such as the contact method, furnace method, and thermal method can be used.
As organic pigments, azo pigments, polycyclic pigments (e.g., phthalocyanine pigments, perylene pigments, perinone pigments, anthraquinone pigments, quinacridone pigments, dioxazine pigments, indigo pigments, thioindigo pigments, isoindolinone pigments, quinophthalone pigments, etc.), dye chelates (e.g., basic dye type chelates, acid dye type chelates, etc.), nitro pigments, nitroso pigments, aniline black, etc. can be used. Among these pigments, those having good affinity with the solvent are preferably used. In addition, resin hollow particles and inorganic hollow particles can also be used.
Specific examples of pigments for black colors include carbon blacks (C.I. Pigment Black 7) such as furnace black, lamp black, acetylene black, and channel black; metals such as copper, iron (C.I. Pigment Black 11), and titanium oxide; and organic pigments such as aniline black (C.I. Pigment Black 1).
Further, for color, C.I. Pigment Yellow 1, 3, 12, 13, 14, 17, 24, 34, 35, 37, 42 (yellow iron oxide), 53, 55, 74, 81, 83, 95, 97, 98, 100, 101, 104, 108, 109, 110, 117, 120, 138, 150, 153, 155, 180, 185, 213, C.I. Pigment Orange 5, 13, 16, 17, 36, 43, 51, C.I. Pigment Red 1, 2, 3, 5, 17, 22, 23, 31, 38, 48:2, 48:2 (Permanent Red 2B (Ca)), 48:3, 48:4, 49:1, 52:2, 53:1, 57:1 (Brilliant Carmine 6B), 60:1, 63:1, 63:2, 64:1, 81, 83, 88, 101 (Red ochre), 1 04, 105, 106, 108 (Cadmium Red), 112, 114, 122 (Quinacridone Magenta), 123, 146, 149, 166, 168, 170, 172, 177, 178, 179, 184, 185, 190, 193, 202, 207, 208, 209, 213, 219, 224, 254, 264, C.I. Pigment Violet 1 (Rhodamine Lake), 3, 5:1, 16, 19, 23, 38, C.I. Pigment Blue 1, 2, 15 (Phthalocyanine Blue), 15:1, 15:2, 15:3, 15:4 (Phthalocyanine Blue), 16, 17:1, 56, 60, 63, C.I. Pigment Green 1, 4, 7, 8, 10, 17, 18, 36, etc.
The dye is not particularly limited, and acid dyes, direct dyes, reactive dyes, and basic dyes can be used. One type of dye may be used alone, or two or more types may be used in combination.
Examples of the dyes include C.I. Acid Yellow 17,23,42,44,79,142, C.I. Acid Red 52,80,82,249,254,289, C.I. Acid Blue 9,45,249, C.I. Acid Black 1,2,24,94, C.I. Food Black 1,2, C.I. Direct Yellow 1,12,24,33,50,55,58,86,132,142,144,173, C.I. Direct Red 1,4,9,80,81,225,227, C.I. Direct Blue 1,2,15,71,86,87,98,165,199,202, C.I. Directed Black 19, 38, 51, 71, 154, 168, 171, 195, C.I. Reactive Red 14, 32, 55, 79, 249, C.I. Reactive Black 3, 4, 35.

The content of colorant in the ink is preferably 0.1% by mass or more and 15% by mass or less, and more preferably 1% by mass or more and 10% by mass or less, from the viewpoints of improving image density, good fixation property and ejection stability.

Methods for dispersing a pigment to obtain an ink include a method of introducing a hydrophilic functional group into the pigment to make it a self-dispersing pigment, a method of dispersing the pigment by coating the surface of the pigment with a resin, and a method of dispersing the pigment using a dispersant.
As a method for making a pigment self-dispersible by introducing a hydrophilic functional group into the pigment, for example, a method for making the pigment dispersible in water by adding a functional group such as a sulfone group or a carboxyl group to the pigment (e.g., carbon) can be mentioned.
A method for dispersing a pigment by coating its surface with a resin includes a method for encapsulating the pigment in a microcapsule to make it dispersible in water. This can be called a resin-coated pigment. In this case, it is not necessary for all of the pigments blended in the ink to be coated with a resin, and uncoated or partially coated pigments may be dispersed in the ink as long as the effects of the present invention are not impaired.
Examples of the method for dispersing using a dispersant include a method for dispersing using a known low molecular weight dispersant or a polymeric dispersant, typified by a surfactant.
As the dispersant, for example, anionic surfactants, cationic surfactants, amphoteric surfactants, nonionic surfactants, etc. can be used depending on the pigment.
RT-100 (nonionic surfactant) manufactured by Takemoto Oil Co., Ltd. and sodium naphthalenesulfonate formalin condensate can also be suitably used as dispersants.
The dispersants may be used alone or in combination of two or more.

<Pigment Dispersion>
It is possible to obtain ink by mixing a pigment with materials such as water or an organic solvent, or it is also possible to manufacture ink by mixing a pigment with other materials such as water and a dispersant to prepare a pigment dispersion, and then mixing the resulting mixture with materials such as water or an organic solvent.
The pigment dispersion is obtained by mixing and dispersing water, a pigment, a pigment dispersant, and other components as required, and adjusting the particle size. Dispersion is preferably performed using a dispersing machine.
The particle size of the pigment in the pigment dispersion is not particularly limited, but in terms of improving the dispersion stability of the pigment and improving the image quality such as ejection stability and image density, the maximum frequency in terms of the maximum number is preferably 20 nm or more and 500 nm or less, and more preferably 20 nm or more and 150 nm or less. The particle size of the pigment can be measured using a particle size analyzer (Nanotrac Wave-UT151, manufactured by Microtrac Bell Co., Ltd.).
The content of the pigment in the pigment dispersion is not particularly limited and can be appropriately selected depending on the purpose. From the viewpoints of obtaining good ejection stability and increasing image density, the content of the pigment is preferably from 0.1% by mass to 50% by mass, and more preferably from 0.1% by mass to 30% by mass.
It is preferable that the pigment dispersion is degassed, if necessary, by filtering coarse particles using a filter, a centrifugal separator, or the like.

<Resin>
The type of resin contained in the ink is not particularly limited and can be appropriately selected depending on the purpose. Examples of the resin include urethane resin, polyester resin, acrylic resin, vinyl acetate resin, styrene resin, butadiene resin, styrene-butadiene resin, vinyl chloride resin, acrylic styrene resin, and acrylic silicone resin.
Resin particles made of these resins may be used. The resin particles may be dispersed in water as a dispersion medium to form a resin emulsion, and the resin particles may be mixed with materials such as coloring materials and organic solvents to obtain an ink. The resin particles may be appropriately synthesized or may be commercially available. These may be used alone or in combination of two or more types of resin particles.

The volume average particle size of the resin particles is not particularly limited and can be appropriately selected depending on the purpose. From the viewpoint of obtaining good fixing property and high image hardness, the volume average particle size is preferably 10 nm or more and 1,000 nm or less, more preferably 10 nm or more and 200 nm or less, and particularly preferably 10 nm or more and 100 nm or less.
The volume average particle size can be measured, for example, by using a particle size analyzer (Nanotrac Wave-UT151, manufactured by Microtrac Bell Co., Ltd.).

There are no particular limitations on the resin content, and it can be selected appropriately depending on the purpose, but from the standpoint of fixation and ink storage stability, it is preferably 1% by mass or more and 30% by mass or less, and more preferably 5% by mass or more and 20% by mass or less, based on the total amount of ink.

There are no particular restrictions on the particle size of the solids in the ink, and they can be selected appropriately depending on the purpose, but in terms of improving image quality such as ejection stability and image density, the maximum frequency in terms of maximum number is preferably 20 nm or more and 1000 nm or less, and more preferably 20 nm or more and 150 nm or less. The solids include resin particles, pigment particles, etc. The particle size can be measured using a particle size analyzer (Nanotrac Wave-UT151, manufactured by Microtrac Bell Co., Ltd.).

<Additives>
If necessary, surfactants, antifoaming agents, antiseptic and antifungal agents, rust inhibitors, pH adjusters, and the like may be added to the ink.

<Surfactant>
As the surfactant, any of silicone-based surfactants, fluorine-based surfactants, amphoteric surfactants, nonionic surfactants, and anionic surfactants can be used.
Silicone surfactants are not particularly limited and can be appropriately selected according to purpose. Among them, those that do not decompose even at high pH are preferred, such as side chain modified polydimethylsiloxane, both end modified polydimethylsiloxane, one end modified polydimethylsiloxane, side chain both end modified polydimethylsiloxane, etc., and those having polyoxyethylene group or polyoxyethylene polyoxypropylene group as modified group are particularly preferred because they show good properties as aqueous surfactants. In addition, polyether modified silicone surfactants can also be used as the silicone surfactant, such as a compound in which a polyalkylene oxide structure is introduced into the Si part side chain of dimethylsiloxane.
As the fluorine-based surfactant, for example, perfluoroalkyl sulfonic acid compound, perfluoroalkyl carboxylic acid compound, perfluoroalkyl phosphate compound, perfluoroalkyl ethylene oxide adduct, and polyoxyalkylene ether polymer compound having perfluoroalkyl ether group in the side chain are particularly preferred because they have low foaming properties.As the perfluoroalkyl sulfonic acid compound, for example, perfluoroalkyl sulfonic acid, perfluoroalkyl sulfonate, etc. can be mentioned.As the perfluoroalkyl carboxylic acid compound, for example, perfluoroalkyl carboxylic acid, perfluoroalkyl carboxylate, etc. can be mentioned.As the polyoxyalkylene ether polymer compound having perfluoroalkyl ether group in the side chain, for example, sulfate ester salt of polyoxyalkylene ether polymer having perfluoroalkyl ether group in the side chain, salt of polyoxyalkylene ether polymer having perfluoroalkyl ether group in the side chain, etc. can be mentioned. Examples _of counter ions _of the salts in these fluorosurfactants include Li, Na, K _{, NH4} , _NH3CH2CH2OH , _{NH2 ( CH2CH2OH} ) ₂ , and NH( _CH2CH2OH ) ₃ .
Examples of amphoteric surfactants include lauryl aminopropionate, lauryl dimethyl betaine, stearyl dimethyl betaine, and lauryl dihydroxyethyl betaine.
Examples of nonionic surfactants include polyoxyethylene alkylphenyl ethers, polyoxyethylene alkyl esters, polyoxyethylene alkylamines, polyoxyethylene alkylamides, polyoxyethylene propylene block polymers, sorbitan fatty acid esters, polyoxyethylene sorbitan fatty acid esters, and ethylene oxide adducts of acetylene alcohol.
Examples of the anionic surfactant include polyoxyethylene alkyl ether acetates, dodecylbenzene sulfonates, laurates, and polyoxyethylene alkyl ether sulfates.
These may be used alone or in combination of two or more.

The silicone surfactant is not particularly limited and can be appropriately selected depending on the purpose. Examples of the silicone surfactant include side-chain modified polydimethylsiloxane, both-end modified polydimethylsiloxane, one-end modified polydimethylsiloxane, and both-end side-chain modified polydimethylsiloxane. Polyether-modified silicone surfactants having a polyoxyethylene group or a polyoxyethylene polyoxypropylene group as a modifying group are particularly preferred because they exhibit good properties as an aqueous surfactant.
Such surfactants may be synthesized appropriately or may be commercially available products, such as those available from BYK-Chemie Co., Ltd., Shin-Etsu Chemical Co., Ltd., Dow Corning Toray Silicone Co., Ltd., Nippon Emulsion Co., Ltd., and Kyoeisha Chemical Co., Ltd.
The polyether-modified silicone surfactant is not particularly limited and can be appropriately selected depending on the purpose. For example, it can be a surfactant represented by the general formula (S-1) in which a polyalkylene oxide structure is introduced into the Si part side chain of dimethylpolysiloxane.

(In the general formula (S-1), m, n, a, and b each independently represent an integer, R represents an alkylene group, and R′ represents an alkyl group.)
As the polyether-modified silicone surfactant, commercially available products can be used, for example, KF-618, KF-642, KF-643 (Shin-Etsu Chemical Co., Ltd.), EMALEX-SS-5602, SS-1906EX (Nihon Emulsion Co., Ltd.), FZ-2105, FZ-2118, FZ-2154, FZ-2161, FZ-2162, FZ-2163, FZ-2164 (Dow Corning Toray Silicone Co., Ltd.), BYK-33, BYK-387 (BYK-Chemie Co., Ltd.), TSF4440, TSF4452, TSF4453 (Toshiba Silicon Co., Ltd.), and the like.

The fluorine-based surfactant is preferably a compound having 2 to 16 fluorine-substituted carbon atoms, and more preferably a compound having 4 to 16 fluorine-substituted carbon atoms.
Examples of fluorine-based surfactants include perfluoroalkyl phosphate compounds, perfluoroalkyl ethylene oxide adducts, and polyoxyalkylene ether polymer compounds having perfluoroalkyl ether groups in side chains, etc. Among these, polyoxyalkylene ether polymer compounds having perfluoroalkyl ether groups in side chains are preferred because they have low foaming properties, and the fluorine-based surfactants represented by general formula (F-1) and general formula (F-2) are particularly preferred.

In the compound represented by the above general formula (F-1), m is preferably an integer of 0 to 10, and n is preferably an integer of 0 to 40 in order to impart water solubility.
General formula (F-2)
C _n F _2n+1- CH ₂ CH(OH)CH ₂ -O-(CH ₂ CH ₂ O) _a -Y
In the compound represented by the above general formula (F-2), Y is H, or CmF _2m+1 where m is an integer from 1 to 6, or CH ₂ CH(OH)CH ₂ -CmF _2m+1 where m is an integer from 4 to 6, or CpH _2p+1 where p is an integer from 1 to 19. n is an integer from 1 to 6. a is an integer from 4 to 14.
As the fluorine-based surfactant, commercially available products may be used. Examples of the commercially available products include Surflon S-111, S-112, S-113, S-121, S-131, S-132, S-141, and S-145 (all manufactured by Asahi Glass Co., Ltd.); Fullard FC-93, FC-95, FC-98, FC-129, FC-135, FC-170C, FC-430, and FC-431 (all manufactured by Sumitomo 3M Limited); Megafa F-470, F-1405, F-474 (all manufactured by Dainippon Ink & Chemicals, Inc.); Zonyl TBS, FSP, FSA, FSN-100, FSN, FSO-100, FSO, FS-300, UR, Capstone FS-30, FS-31, FS-3100, FS-34, FS-35 (all manufactured by Chemours); FT-110, FT- 250, FT-251, FT-400S, FT-150, FT-400SW (all manufactured by Neos Co., Ltd.), Polyfox PF-136A, PF-156A, PF-151N, PF-154, PF-159 (manufactured by Omnova), Unidyne DSN-403N (manufactured by Daikin Industries, Ltd.), and the like. Among these, preferred are those which have good print quality, particularly color development and paper adhesion. From the viewpoint of significantly improving the permeability, wettability and uniform dyeing property, FS-3100, FS-34 and FS-300 manufactured by Chemours Corporation, FT-110, FT-250, FT-251, FT-400S, FT-150 and FT-400SW manufactured by Neos Co., Ltd., Polyfox PF-151N manufactured by Omnova Co., Ltd. and Unidyne DSN-403N manufactured by Daikin Industries, Ltd. are particularly preferred.

The content of the surfactant in the ink is not particularly limited and can be selected appropriately depending on the purpose, but from the viewpoint of excellent wettability, ejection stability, and improved image quality, it is preferably 0.001% by mass or more and 5% by mass or less, and more preferably 0.05% by mass or more and 5% by mass or less.

<Antifoaming agent>
The defoaming agent is not particularly limited, and examples thereof include silicone-based defoaming agents, polyether-based defoaming agents, and fatty acid ester-based defoaming agents. These may be used alone or in combination of two or more. Among these, silicone-based defoaming agents are preferred because of their excellent foam breaking effect.

<Anti-septic and anti-fungal agents>
The antiseptic and antifungal agent is not particularly limited, and examples thereof include 1,2-benzisothiazolin-3-one.

<Rust inhibitor>
The rust inhibitor is not particularly limited, and examples thereof include acid sulfite and sodium thiosulfate.

<pH Adjuster>
There are no particular limitations on the pH adjuster, so long as it is capable of adjusting the pH to 7 or higher, and examples of the pH adjuster include amines such as diethanolamine and triethanolamine.

The physical properties of the ink are not particularly limited and can be appropriately selected depending on the purpose. For example, it is preferable that the viscosity, surface tension, pH, etc. are within the following ranges.
The viscosity of the ink at 25°C is preferably 5 mPa·s or more and 30 mPa·s or less, and more preferably 5 mPa·s or more and 25 mPa·s or less, in terms of improving the print density and character quality and obtaining good ejection properties. Here, the viscosity can be measured using, for example, a rotational viscometer (RE-80L manufactured by Toki Sangyo Co., Ltd.). The measurement conditions are 25°C, a standard cone rotor (1°34'×R24), a sample liquid volume of 1.2 mL, a rotation speed of 50 rpm, and 3 minutes.
The surface tension of the ink is preferably 35 mN/m or less, and more preferably 32 mN/m or less at 25° C., in order to ensure that the ink is appropriately leveled on the recording medium and the drying time of the ink is shortened.
The pH of the ink is preferably from 7 to 12, and more preferably from 8 to 11, from the viewpoint of preventing corrosion of metal members that come into contact with the ink.

<Pretreatment solution>
The pretreatment liquid contains a flocculant, an organic solvent, and water, and may contain, as necessary, a surfactant, an antifoaming agent, a pH adjuster, an antiseptic/fungal agent, an antirust agent, and the like.
The organic solvent, surfactant, defoamer, pH adjuster, antiseptic/fungal agent, and rust inhibitor may be the same as those used in ink, and other materials used in known treatment liquids may be used.
The type of the flocculant is not particularly limited, and examples thereof include water-soluble cationic polymers, acids, and polyvalent metal salts.

<Post-processing solution>
The post-treatment liquid is not particularly limited as long as it can form a transparent layer. The post-treatment liquid is obtained by selecting and mixing organic solvents, water, resins, surfactants, defoamers, pH adjusters, antiseptics, antifungals, rust inhibitors, etc. as necessary. The post-treatment liquid may be applied to the entire recording area formed on the recording medium, or may be applied only to the area where the ink image is formed.

In the present invention, the ink must be designed so that its dynamic surface tension at 25°C and with a life time of 15 ms is 30 mN/m or more and 50 mN/m or less. The dynamic surface tension can be controlled by the type and amount of surfactant added.

The dynamic surface tension can be measured by a known method, but in the present invention, it is preferable to measure by the maximum bubble pressure method. A dynamic surface tension measuring device using the maximum bubble pressure method is commercially available, for example, DynoTeter (manufactured by SITA).
The maximum bubble pressure method is a method in which bubbles are released from the tip of a probe immersed in the liquid to be measured, and the surface tension is calculated from the maximum pressure required to release the bubbles.
When the radius of the bubble is equal to the radius of the probe tip, the maximum pressure is reached, and the dynamic surface tension σ of the ink at this time is expressed by the following equation:

σ=(ΔP·r)/2
(where r is the radius of the probe tip, and ΔP is the difference between the maximum and minimum pressures on the bubble)

In addition, the lifetime in this invention refers to the time from when a bubble leaves the probe and a new surface is formed until the next maximum bubble pressure in the maximum bubble pressure method.

In the above embodiment, the focus is on the distance between the nozzle surface and the fabric, but the present invention is not limited to this, and the focus may be on the distance between the nozzle surface and the fabric holding member. Below, other embodiments of the image forming device according to the present invention are described.

The image forming device of this embodiment has ink having a dynamic surface tension of 30 mN/m to 50 mN/m with a life time of 15 ms at 25°C, a head for ejecting the ink, and a fabric holding member for holding the fabric, the head having a nozzle surface, and characterized in that the distance between the nozzle surface and the fabric holding member when the ink is ejected onto a fabric mainly composed of synthetic fibers is shorter than the distance between the nozzle surface and the fabric holding member when the ink is ejected onto a fabric mainly composed of natural fibers.

By changing the distance between the nozzle surface and the fabric holding member (e.g., platen 15), the distance between the head and the fabric for fabrics primarily composed of synthetic fibers can be made shorter than the distance between the head and the fabric for fabrics primarily composed of natural fibers. As a result, similar to the above embodiment, images with high color development and little unevenness in image density can be obtained for both fabrics primarily composed of natural fibers and fabrics primarily composed of synthetic fibers. Note that the configurations and preferred configurations of the above embodiment can also be applied to this embodiment, and so a description thereof will be omitted.

In the above embodiment, the fabric mainly made of natural fibers and the fabric mainly made of synthetic fibers are described, but the following embodiments are also possible in the present invention.
That is, the image forming apparatus of this embodiment has ink having a dynamic surface tension of 30 mN/m or more and 50 mN/m or less and a lifetime of 15 ms at 25°C, and a head for ejecting the ink, the head having a nozzle surface, and characterized in that the distance between the nozzle surface and the fabric when the ink is ejected onto a fabric containing synthetic fibers is shorter than the distance between the nozzle surface and the fabric when the ink is ejected onto the fabric made of natural fibers.

In this embodiment, "fabric made of natural fibers" refers to fabric containing 100% natural fibers by mass. This embodiment may also have a first recording mode and a second recording mode, and the first recording mode ejects ink onto fabric made of natural fibers, and the second recording mode ejects ink onto fabric containing synthetic fibers. This embodiment also provides images with high color development and little unevenness in image density for both fabric made of natural fibers and fabric containing synthetic fibers. The configurations and preferred configurations of the above embodiments are also applicable to this embodiment, and explanations will be omitted.

The present invention will be explained in more detail below with reference to examples, but the present invention is not limited to these examples. Parts indicate parts by weight.

<Preparation of Black Pigment Dispersion>
The following mixture was premixed and then circulated and dispersed for 7 hours in a disk-type bead mill (KDL type, manufactured by Shinmaru Enterprises Co., Ltd., media: zirconia balls with a diameter of 0.3 mm) to obtain a black pigment dispersion (pigment concentration: 15% by mass).
Carbon black pigment (product name: Monarch 800, manufactured by Cabot Corporation) 15 parts Anionic surfactant (product name: Paionin A-51-B, manufactured by Takemoto Oil Co., Ltd.) 2 parts Ion-exchanged water 83 parts

[Production of Resin Particle Dispersion]
A resin particle dispersion was obtained by the following procedure.
First, 50 parts of T5651 (polycarbonate diol, manufactured by Asahi Kasei) were charged into a 500 mL separable flask equipped with a stirrer, a thermometer, and a reflux tube, 3 parts of dimethylolpropionic acid, 24 parts of isophorone diisocyanate, and 42 parts of acetone dehydrated with a molecular sieve. The temperature was raised to 70 ° C. under a nitrogen stream, and then 200 ppm of tin 2-ethylhexanoate was added. The reaction was carried out at 70 ° C. for 3 to 10 hours while measuring the isocyanate concentration in the system. Next, the temperature in the system was lowered to 40 ° C., and after adding triethylamine as necessary, 140 parts of ion-exchanged water was added while stirring at a speed of 300 rpm, and after stirring for 1 hour, 2 parts of isophorone diamine was added and stirred for 3 to 6 hours. Thereafter, the mixture was cooled to room temperature, the solvent was distilled off with an evaporator, and the solid content was adjusted to 30% with ion-exchanged water to obtain a resin particle dispersion.

[Preparation of pretreatment solution]
The materials were mixed according to the following formulation, stirred for one hour, and then pressure filtered through a 1.2 μm cellulose acetate membrane filter to obtain a pretreatment liquid.
Propylene glycol 25 parts Triethylene glycol 5 parts Wet 270 (Evonik) 0.5 parts BYK348 (BYK-Chemie) 0.5 parts Envirogem AD01 (AIR PRODUCT) 0.5 parts Proxel LV: Benzisothiazolin-3-one solution (Lonza Japan) 0.3 parts Magnesium chloride hexahydrate 5 parts Ion-exchanged water Remainder (total 100 parts)

[Preparation of black ink]
Black inks 1 to 7 were prepared by mixing the components according to the formulations (mass %) in Table 1 below.

Inks 1 to 7 were obtained by mixing the components in the ratios (mass %) shown in Table 1 above, stirring for one hour, and then filtering under pressure through a 1.2 μm cellulose acetate membrane filter.
The materials in the table are as follows:
Surfynol 420: acetylene-based surfactant (manufactured by Nissin Chemical Industry Co., Ltd.)
BYK348: Silicone surfactant (manufactured by BYK-Chemie)
AD01: Envirogem AD01 (manufactured by AIR PRODUCT)
Proxel LV: Benzisothiazolin-3-one solution (manufactured by Lonza Japan)
The dynamic surface tensions of the resulting inks 1 to 7 at 25° C. with a life time of 15 ms are shown in Table 1.

The image forming apparatus shown in FIGS. 1 to 7 was used to create evaluation images of fabrics mainly composed of natural fibers.
The image forming apparatus was filled with the pretreatment liquid and the black ink, and the black ink was applied to a cotton T-shirt manufactured by Tom's Co., Ltd. (Printstar 085-CVT, white) at a deposition amount of 1.5 mg/ ^cm2 to form a solid image. The image was then dried for 1 minute using a heat press set at 160°C to obtain each evaluation image.

The image forming apparatus shown in FIGS. 1 to 7 was used to create evaluation images of fabrics mainly made of synthetic fibers.
The image forming apparatus was filled with a pretreatment liquid and a black ink, and the pretreatment liquid was uniformly applied to a polyester T-shirt (glimmer 00300-ACT, white) manufactured by Tom's Co., Ltd. in an amount of 0.5 mg/ ^cm2 . Then, while the T-shirt was still wet, black ink was applied to the T-shirt in an amount of 1.5 mg/ ^cm2 to form a solid image. The T-shirt was then dried for 1 minute in a heat press set at 160°C, thereby obtaining images for evaluation.

The ink drop size was adjusted by controlling the driving voltage.
The landing distance between droplets successively ejected from the head was adjusted by controlling the drive frequency.
In addition, the distance (gap) between the head and the fabric was adjusted as shown in Table 2 by controlling the lifting and lowering function of the platen.
The distance (gap) between the head and the fabric was measured after removing any fuzz from the fabric, and the fabric was smoothed with a pressing member before the measurement.

[Evaluation of image density]
Each of the obtained evaluation images was color-measured using X-rite exact, and the image OD was evaluated.
〔Evaluation criteria〕
A: OD is 1.3 or more B: OD is 1.25 or more and less than 1.3 C: OD is 1.20 or more and less than 1.25 D: OD is less than 1.20

[Evaluation of image density unevenness]
The obtained evaluation images were each evaluated according to the following criteria.
〔Evaluation criteria〕
A: No unevenness in image density is observed and it is clear. B: Almost no unevenness in image density is observed. C: Some unevenness in image density is observed but it is at a level that is practically usable. D: Unevenness in image density is clearly observed and it is at a level that is not suitable for practical use.

The results are shown in Table 2. Comparative Example 1 is an example in which the second recording mode was not selected and an image was formed on polyester fiber using the first recording mode.

The results in Table 2 show that the image forming apparatus of each embodiment can provide images with high color development and little unevenness in image density for both fabrics whose main component is natural fibers and fabrics whose main component is synthetic fibers.

REFERENCE SIGNS LIST 10 Carriage 11 First head 12 Second head 13 Carriage scanning rail 14 Exhaust section 15 Platen 16 Support member 17 Platen moving base 18 Maintenance unit 19 Platen moving rail 22 Apparatus main body 30 Recording medium 40 Heating means

JP 2017-51952 A JP 2011-246856 A JP 2015-150829 A

Claims (12)

The ink has a dynamic surface tension of 30 mN/m or more and 50 mN/m or less with a life time of 15 ms at 25° C., and a head that ejects the ink onto a fabric,
the head includes a nozzle surface on which nozzles for ejecting the ink are formed and which faces the fabric;
An image forming apparatus characterized in that, when the ink is ejected from the nozzle onto a fabric primarily composed of natural fibers, the distance between the nozzle surface and the fabric is shorter than the distance between the nozzle surface and the fabric primarily composed of natural fibers and to which a pretreatment liquid containing a coagulant is applied and when the ink is ejected from the nozzle onto the fabric primarily composed of synthetic fibers. The image forming device according to claim 1, characterized in that the distance between the nozzle surface and the fabric when the ink is ejected onto the fabric mainly made of synthetic fibers is shorter by 1 mm or more than the distance between the nozzle surface and the fabric when the ink is ejected onto the fabric mainly made of natural fibers. The image forming device according to claim 1 or 2, wherein the distance between the nozzle surface and the fabric when the ink is ejected onto the fabric mainly composed of natural fibers and the fabric mainly composed of synthetic fibers is 0.5 mm or more and 5 mm or less. The pretreatment liquid and a head that ejects the pretreatment liquid,
4. The image forming apparatus according to claim 1, wherein the head for ejecting the pretreatment liquid ejects the pretreatment liquid onto the fabric containing synthetic fibers as a main component. A fabric holding member is provided to hold and transport the fabric,
5. The image forming apparatus according to claim 4, wherein the head that ejects the pretreatment liquid is located upstream of the head that ejects the ink in the transport direction of the fabric. The image forming apparatus according to any one of claims 1 to 5, characterized in that the ink has a dynamic surface tension of 32 mN/m or more and 45 mN/m or less at 25°C and a life time of 15 ms. An image forming apparatus according to any one of claims 1 to 6, comprising a detection means for detecting the components of the fabric. An image forming device according to any one of claims 1 to 7, comprising an input unit for inputting the type of fabric and/or the components of the fabric. The image forming apparatus according to claim 7 or 8, wherein the distance between the nozzle surface and the fabric when the ink is ejected from the nozzle is changed based on the information about the fabric obtained by the detection means or the input unit. The ink ejection apparatus includes an ink having a dynamic surface tension of 30 mN/m or more and 50 mN/m or less at a life time of 15 ms at 25° C., a head for ejecting the ink onto a fabric, and a fabric holding member for holding the fabric,
the head includes a nozzle surface on which nozzles for ejecting the ink are formed and which faces the fabric;
An image forming apparatus characterized in that the distance between the nozzle surface and the fabric holding member when the ink is ejected from the nozzle onto a fabric primarily composed of synthetic fibers and to which a pretreatment liquid containing a coagulant has been applied is shorter than the distance between the nozzle surface and the fabric holding member when the ink is ejected from the nozzle onto a fabric primarily composed of natural fibers. The ink has a dynamic surface tension of 30 mN/m or more and 50 mN/m or less with a life time of 15 ms at 25° C., and a head that ejects the ink onto a fabric,
the head includes a nozzle surface on which nozzles for ejecting the ink are formed and which faces the fabric;
An image forming apparatus characterized in that, when the ink is ejected from the nozzle onto a fabric made of natural fibers, the distance between the nozzle surface and the fabric is shorter than the distance between the nozzle surface and the fabric when the ink is ejected from the nozzle onto the fabric made of synthetic fibers and to which a pretreatment liquid containing a coagulant has been applied . The ink jet head has a dynamic surface tension of 30 mN/m or more and 50 mN/m or less and has a life time of 15 ms at 25° C., and ejects the ink onto a fabric.
the head includes a nozzle surface on which nozzles for ejecting the ink are formed and which faces the fabric;
An image forming apparatus characterized in that, when the ink is ejected from the nozzle onto a fabric primarily composed of natural fibers, the distance between the nozzle surface and the fabric is shorter than the distance between the nozzle surface and the fabric primarily composed of natural fibers and to which a pretreatment liquid containing a coagulant is applied and when the ink is ejected from the nozzle onto the fabric primarily composed of synthetic fibers.

Images