Image recording method and image recording device

Abstract

An image recording method including: a recording step in which a white ink containing water and a white pigment is applied on one of the surfaces of a non-permeable substrate by the inkjet method and a white image is recorded; and a winding step in which the non-permeable substrate having the white image recorded thereon is wound while tension is applied thereto, wherein when the front surface energy difference between the other surface of the non-permeable substrate and the front surface of the white image in units of mJ / m2 is denoted by ΔE and the tension in units of N / m is denoted by P, the value of the ratio ΔE / P obtained by dividing ΔE by P is 0.06-0.60.

Description

Image recording method and image recording device

[0001] The present disclosure relates to an image recording method and an image recording device.

[0002]

[0003] Conventionally, various studies have been conducted on image recording methods. For example, Patent Document 1 discloses a water-based inkjet ink composition that can provide recorded matter excellent in abrasion resistance and sticking resistance while ensuring ejection stability during recording, the water-based inkjet ink composition comprising resin fine particles, a nonionic surfactant, a resin-dissolving solvent, and water, wherein the total acid value of the resin fine particles and, if the water-based inkjet ink composition contains a dispersant resin, the acid value of the dispersant resin is 200 (mg KOH / 100 g ink) or less.

[0003] Patent Document 1: JP 2018-165314 A

[0004] In image recording, a white image is recorded on a non-permeable substrate by applying a white ink by an inkjet method, and the non-permeable substrate with the recorded white image is then wound up. It may be necessary to suppress blocking of the white image. However, the inventors have found through their studies that attempts to suppress blocking of the white image in the image recording process tend to result in misalignment of the non-permeable substrate during winding. Therefore, it may be necessary to suppress blocking of the white image and misalignment of the non-permeable substrate during image recording. Here, "blocking of the white image" refers to the phenomenon in which, after the non-permeable substrate with a recorded white image is wound up, the white image adheres to the backside of the non-permeable substrate that is in contact with the front side of the white image. Furthermore, "misalignment of the non-permeable substrate during winding" refers to the phenomenon in which, as the non-permeable substrate with a recorded white image is wound up, the position of the non-permeable substrate gradually shifts in the axial direction of the winding.

[0005] The present disclosure has been made in consideration of these circumstances, and aims to provide an image recording method and an image recording device that can record a white image on a non-permeable substrate and suppress blocking of the white image and misalignment of the non-permeable substrate when the non-permeable substrate on which the white image has been recorded is wound up.

[0006] The present disclosure includes the following aspects: <1> A method for recording a white image by applying a white ink containing water and a white pigment onto one surface of a non-permeable substrate by an inkjet method, and a winding step of winding up the non-permeable substrate on which the white image has been recorded while applying tension, wherein the difference in the amount of tension between the other surface of the non-permeable substrate and the surface of the white image is mJ / m ２An image recording method, wherein a ΔE / P ratio, which is the value obtained by dividing ΔE by P, where ΔE is a difference in surface energy in units of 100 kJ / cm and P is a tension in units of N / m, is 0.06 to 0.60. <2> The image recording method according to <1>, wherein the recording step further includes applying a colored ink containing water and a color pigment onto one side of the non-permeable substrate by an inkjet method to record a colored image. <3> The image recording method according to <2>, wherein the colored image is recorded before the white image and is disposed between the one side of the non-permeable substrate and the white image. <4> The image recording method according to any one of <1> to <3>, wherein ΔE is 5.0 to 25.0. <5> The image recording method according to any one of <1> to <4>, wherein P is 30 to 150. <6> The image recording method according to any one of <1> to <5>, wherein the ΔE / P ratio is 0.10 to 0.50. <7> The image recording method according to any one of <1> to <6>, further comprising, before the recording step, a step of applying a pretreatment liquid containing water and a flocculant onto one surface of the non-permeable substrate, wherein the recording step involves applying a white ink to the area on the one surface to which the pretreatment liquid has been applied, to record a white image. <8> An image recording apparatus for use in the image recording method according to any one of <1> to <7>, comprising: a recording unit including an inkjet head for applying the white ink onto one surface of the non-permeable substrate, and performing the recording step of recording the white image on one surface of the non-permeable substrate; and a winding unit including a winding device for winding up the non-permeable substrate on which the white image has been recorded, under tension, and performing the winding step, wherein the ΔE / P ratio is 0.06 to 0.60.

[0007] According to one embodiment of the present disclosure, there is provided an image recording method and an image recording device that can record a white image on a non-permeable substrate and suppress blocking of the white image and misalignment of the non-permeable substrate when the non-permeable substrate on which the white image has been recorded is wound up.

[0008] FIG. 1 is a diagram conceptually illustrating an example of an image recording device used to implement an image recording method of the present disclosure.

[0009] In the present disclosure, a numerical range indicated using "to" means a range that includes the numerical values ​​before and after "to" as the minimum and maximum values, respectively. In the numerical ranges described in stages in this specification, the upper or lower limit value described in a certain numerical range may be replaced with the upper or lower limit value of another numerical range described in stages. Furthermore, in the numerical ranges described in this specification, the upper or lower limit value described in a certain numerical range may be replaced with a value shown in the examples.

[0010] In the present disclosure, the amount of each component in a composition means the total amount of the components in the composition unless otherwise specified, when the composition contains multiple substances corresponding to each component. In the present disclosure, a combination of two or more preferred aspects is a more preferred aspect. In the present disclosure, the term "process" includes not only an independent process, but also a process that cannot be clearly distinguished from other processes, as long as the intended purpose of the process is achieved.

[0011] In this disclosure, the term "image" refers to the ink film itself when no pretreatment liquid is used, and refers to a laminated film of the pretreatment liquid film and the ink film when a pretreatment liquid is used. In this disclosure, the term "image recording" refers to the formation of an image. The concept of "image" in this disclosure also includes solid images.

[0012] In the present disclosure, the expression "applying ink onto a substrate" encompasses an embodiment in which ink is directly applied to the surface of a substrate, and an embodiment in which, when, for example, layer A is formed on the substrate, ink is directly applied to the surface of layer A. In the present disclosure, unless otherwise specified, the "upstream side" means the upstream side of the non-permeable substrate in the transport direction, and the "downstream side" means the downstream side of the non-permeable substrate in the transport direction, unless otherwise specified.

[0013] [Image Recording Method] The image recording method (hereinafter also referred to as "recording method") of the present disclosure includes: a recording step of applying a white ink containing water and a white pigment onto one surface (hereinafter also referred to as "front surface") of a non-permeable substrate by an inkjet method to record a white image; and a winding step of winding up the non-permeable substrate on which the white image has been recorded, while applying tension, and the difference in the amount of the ink jetting between the other surface (hereinafter also referred to as "back surface") of the non-permeable substrate and the surface of the white image is mJ / m ２ In this image recording method, when the surface energy difference in units of tensile strength is ΔE and the tension in units of N / m is P, the ΔE / P ratio, which is the value obtained by dividing ΔE by P, is 0.06 to 0.60.

[0014] According to the recording method of the present disclosure, a white image is recorded on a non-permeable substrate, and when the non-permeable substrate on which the white image is recorded is wound up, blocking of the white image and misalignment of the non-permeable substrate can be suppressed. The reason for this effect is presumed to be as follows.

[0015] The reason why blocking of the white image can be suppressed is presumed to be as follows: ２The larger the value of ΔE, which is the surface energy difference in units of N / m (hereinafter also referred to as "surface energy difference ΔE"), the more advantageous it is for suppressing white image blocking. This is because the larger the surface energy difference ΔE, the lower the affinity between the back surface of the impermeable substrate and the white image that comes into contact with this back surface after winding. On the other hand, the smaller the value of the tension (i.e., P (hereinafter also referred to as "tension P")) in units of N / m that is applied to the impermeable substrate when winding up the impermeable substrate on which a white image has been recorded, the more advantageous it is for suppressing white image blocking. This is because the smaller the tension P, the weaker the winding of the impermeable substrate, and as a result, the weaker the pressing force between the back surface of the impermeable substrate and the white image that comes into contact with this back surface in the wound impermeable substrate. For these reasons, the larger the ΔE / P ratio, which is the value obtained by dividing ΔE by P, the more advantageous it is for suppressing white image blocking. Specifically, in the recording method of the present disclosure, the ΔE / P ratio is 0.06 or more, so that blocking of the white image is suppressed.

[0016] The reason why winding slippage of the non-permeable substrate can be suppressed is presumed to be as follows. The smaller the surface energy difference ΔE, the more advantageous it is for preventing winding slippage of the non-permeable substrate. This is because the smaller the surface energy difference ΔE, the higher the affinity between the back surface of the non-permeable substrate and the white image that comes into contact with this back surface after winding, making it less likely for the two to slip. On the other hand, the larger the tension P, the more advantageous it is for preventing winding slippage of the non-permeable substrate. This is because the greater the tension P, the stronger the winding tightness of the non-permeable substrate, and as a result, the stronger the pressing force between the back surface of the non-permeable substrate and the white image that comes into contact with this back surface after winding. For these reasons, the larger the ΔE / P ratio, which is the value obtained by dividing ΔE by P, the more advantageous it is for preventing winding slippage of the non-permeable substrate. Specifically, in the recording method of the present disclosure, a ΔE / P ratio of 0.60 or less suppresses winding slippage of the non-permeable substrate.

[0017] <ΔE / P ratio> As described above, the ΔE / P ratio in the present disclosure is 0.06 to 0.60. The ΔE / P ratio is preferably 0.10 to 0.50. When the ΔE / P ratio is 0.10 or more, blocking of the white image is further suppressed. When the ΔE / P ratio is 0.50 or less, winding slippage of the non-permeable substrate is further suppressed.

[0018] <Surface Energy Difference ΔE> The surface energy difference ΔE is the difference in surface energy between the back surface of the impermeable substrate and the front surface of the white image. Here, the surface energy difference ΔE is the dispersion component γ of the surface energy of the back surface of the impermeable substrate. Ｓ ｄ (1) and the hydrogen bond component γ of the surface energy of the back surface of the impermeable substrate. Ｓ ｈ (1) and the dispersion component γ of the surface energy of the white image Ｓ ｄ (2) and the hydrogen bond component γ of the surface energy of the white image. Ｓ ｈ Based on (2) and the following formula, ΔE=((γ Ｓ ｄ (2)-γ Ｓ ｄ (1) ２ + (γ Ｓ ｈ (2)-γ Ｓ ｈ (1) ２ ) １／２

[0019] The surface energy difference ΔE is not particularly limited as long as the ΔE / P ratio falls within the above-mentioned range. The surface energy difference ΔE is, for example, 35.0 or less, preferably 1.0 to 30.0, more preferably 5.0 to 25.0, and even more preferably 7.0 to 24.0.

[0020] <Method for Measuring Surface Energy (Hydrogen Bond Component and Dispersion Component)> In the present disclosure, the surface energy (hydrogen bond component and dispersion component) of a solid surface (i.e., each of the back surface of the impermeable substrate and the surface of the white image) refers to a value calculated by the Owens-Wendt method.

[0021] The surface energy of a white image is measured by recording a white image on a non-permeable substrate using the same white ink as used in the recording process under the same conditions as those in the recording process, and using the non-permeable substrate on which the white image has been recorded (hereinafter also referred to as an "image sample"). The contact angles of water and diiodomethane described below are measured within 30 minutes after the image sample is prepared (i.e., after the ink has dried). The surface energy of the back surface of the non-permeable substrate is measured using the back surface of the non-permeable substrate itself used in the recording process.

[0022] The contact angles of water and diiodomethane with respect to a solid surface (i.e., the surface of a white image in an image sample, or the back surface of a non-permeable substrate) are measured using a contact angle meter. For example, a contact angle meter with the product name "DM-501" manufactured by Kyowa Interface Science Co., Ltd. can be used. The surface energy of the solid surface is calculated by the Owens-Wendt method using the measured contact angles of water and diiodomethane with respect to the solid surface and the dispersion and hydrogen bond components of water and diiodomethane. The Owens-Wendt method is described in DK Owens and R.C. Wendt, Journal of Applied Polymer Science, Vol. 13, pp. 1741-1747, (1969).

[0023] A specific calculation method will be described below. When a liquid is dropped onto a solid surface, the following equations hold for each parameter at the interface between the solid surface and the liquid. Equation 1 below is known as Young's equation. Equation 2 below is known as Dupre's equation. Equations 3, 4, and 5 below are known as equations based on the Owens-Wendt method.

[0024] gamma Ｓ = γ Ｌ cosθ+γ ＳＬ ... (1) W = γ Ｓ +γ Ｌ -γ ＳＬ …(2) γ Ｓ = γ Ｓ ｄ +γ Ｓ ｈ …(3) γＬ = γ Ｌ ｄ +γ Ｌ ｈ ...(4) W = 2(γ Ｓ ｄ gamma Ｌ ｄ ) １／２ +2 (γ Ｓ ｈ gamma Ｌ ｈ ) １／２ …(5)

[0025] In Equations 1 to 5, the details of each symbol are as follows: θ: contact angle of the liquid with the solid surface γ: Ｓ ...Surface energy of solid surface γ Ｌ ...surface energy of liquid γ ＳＬ …Interfacial energy between solid surface and liquid W…Work of adhesion γ Ｓ ｄ ...dispersion component of the surface energy of a solid surface γ Ｓ ｈ ...Hydrogen bond component of the surface energy of a solid surface γ Ｌ ｄ ...dispersion component of the liquid surface energy γ Ｌ ｈ ...hydrogen bond component of the liquid surface energy

[0026] From the above formulas 1 to 5, the following formula 6 is obtained: (γ Ｓ ｄ gamma Ｌ ｄ ) １／２ + (γ Ｓ ｈ gamma Ｌ ｈ ) １／２ = γ Ｌ (1+cosθ) / 2...(6)

[0027] As the liquid in Formula 6, water and diiodomethane are used, resulting in Formula 6A and Formula 6B. (γ Ｓ ｄ gamma Ｌ１ ｄ ) １／２ + (γ Ｓ ｈ gamma Ｌ１ ｈ ) １／２ = γＬ１ (1+cosθ1) / 2...(6A) (γ Ｓ ｄ gamma Ｌ２ ｄ ) １／２ + (γ Ｓ ｈ gamma Ｌ２ ｈ ) １／２ = γ Ｌ２ (1+cosθ2) / 2...(6B)

[0028] In Formula 6A and Formula 6B, the details of each symbol are as follows: θ1: contact angle of water on the solid surface θ2: contact angle of diiodomethane on the solid surface γ Ｌ１ ...surface energy of water (72.8 mN / m) γ Ｌ１ ｄ ...dispersion component of water surface energy (21.8 mN / m) γ Ｌ１ ｈ ...Hydrogen bond component of water surface energy (51.0 mN / m) γ Ｌ２ ...Surface energy of diiodomethane (50.8 mN / m) γ Ｌ２ ｄ ...dispersion component of surface energy of diiodomethane (50.8 mN / m) γ Ｌ２ ｈ ...Hydrogen bond component of surface energy of diiodomethane (0 mN / m) The values ​​in parentheses are values ​​given in the literature.

[0029] In Equation 6A and Equation 6B, θ1, θ2, γ Ｌ１ , γ Ｌ１ ｄ , γ Ｌ１ ｈ , γ Ｌ２ , γ Ｌ２ ｄ , and γ Ｌ２ ｈ By substituting γ Ｓ ｄ and γ Ｓ ｈ The values ​​measured by the above measurement method are used as θ1 and θ2.

[0030] In Equation 3, the calculated γ Ｓ ｄ and γ Ｓ ｈBy substituting, the surface energy of the solid surface γ Ｓ can be calculated.

[0031] The surface energy of the back surface of the impermeable substrate and the surface energy of the front surface of the white image are not particularly limited as long as they satisfy the above-mentioned range of the ΔE / P ratio. Ｓ is, for example, 30.0 mJ / m ２ ~50.0 mJ / m ２ The dispersion component of the surface energy of the back surface of the impermeable substrate, γ Ｓ ｄ is, for example, 30.0 mJ / m ２ ~50.0 mJ / m ２ The hydrogen bonding component of the surface energy of the backside of the impermeable substrate, γ Ｓ ｈ is, for example, 0 mJ / m ２ ~3.0 mJ / m ２ The surface energy of the white image γ Ｓ is, for example, 35.0 mJ / m ２ ~80.0 mJ / m ２ The dispersion component of the surface energy of the white image γ Ｓ ｄ is, for example, 30.0 mJ / m ２ ~50.0 mJ / m ２ The hydrogen bond component γ of the surface energy of the white image Ｓ ｈ is, for example, 5.0 mJ / m ２ ~30.0 mJ / m ２ is.

[0032] <Tension P> In the present disclosure, tension P (i.e., tension expressed in units of N / m when the impermeable substrate is wound up) refers to the tension of the impermeable substrate immediately before the winding device that winds up the impermeable substrate on which a white image has been recorded (specifically, in an area within 1 m from the winding device) (hereinafter also referred to as "tension P at the winding section"). In the present disclosure, tension P (unit: N / m) refers to a value measured with a tension meter.

[0033] The tension P is not particularly limited as long as the ΔE / P ratio falls within the above-mentioned range. The tension P is, for example, 20 to 160, preferably 30 to 150, more preferably 35 to 100, and even more preferably 40 to 80.

[0034] In the recording method of the present disclosure, tension may also be applied to a region of the non-permeable substrate that is more than 1 m upstream from the winding section (for example, a region where ink is applied). In this case, the tension P and the tension in the upstream region may be the same or different.

[0035] <Recording Step> The recording method of the present disclosure includes a recording step of applying a white ink containing water and a white pigment onto the front surface of an impermeable substrate by an inkjet method to record a white image.

[0036] (Impermeable substrate) In the present disclosure, the impermeability of an impermeable substrate refers to a property in which the water absorption rate over 24 hours measured in accordance with ASTM D570-98 (2018) is 2.5% or less. Here, the unit of water absorption rate, "%", is based on mass. The water absorption rate is preferably 1.0% or less, and more preferably 0.5% or less.

[0037] Examples of materials for the impermeable substrate include glass, metals (e.g., aluminum, zinc, copper, etc.), and resins (e.g., polyvinyl chloride, cellulose diacetate, cellulose triacetate, cellulose propionate, cellulose butyrate, cellulose acetate butyrate, cellulose nitrate, polyethylene terephthalate, polyethylene, polystyrene, polypropylene, polycarbonate, polyvinyl acetal, nylon, acrylic resin, etc.).

[0038] The material of the impermeable substrate is preferably a resin, that is, the impermeable substrate is preferably a resin substrate.

[0039] Among these, from the viewpoint of versatility, the material of the impermeable substrate is preferably polypropylene, polyethylene, polyethylene terephthalate, nylon, acrylic resin, or polyvinyl chloride.

[0040] The shape of the impermeable substrate is preferably a sheet (film) or plate, and examples of such a shape of the impermeable substrate include a glass plate, a metal plate, a resin sheet (resin film), a plastic-laminated paper, a metal-laminated or metal-deposited paper, and a metal-laminated or metal-deposited plastic sheet (plastic film).

[0041] Examples of impermeable resin substrates include resin sheets (resin films), and specific examples include flexible packaging materials for packaging foods and the like, and floor guide panels in mass retailers.

[0042] Examples of impermeable substrates include not only sheet-shaped (film-shaped) or plate-shaped impermeable substrates, but also textiles (woven fabrics) and nonwoven fabrics formed from impermeable fibers.

[0043] The thickness of the impermeable substrate is preferably 0.1 μm to 1,000 μm, more preferably 0.1 μm to 800 μm, and even more preferably 1 μm to 500 μm.

[0044] At least one of the front and back surfaces of the impermeable substrate may be subjected to a surface treatment. Examples of surface treatments include, but are not limited to, corona treatment, plasma treatment, flame treatment, heat treatment, abrasion treatment, light irradiation treatment (e.g., UV treatment), and flame treatment. Corona treatment can be performed using, for example, a Corona Master (product name "PS-10S", manufactured by Shinko Electric Meter Co., Ltd.). The conditions for the surface treatment may be appropriately selected depending on the type of impermeable substrate, etc. In addition, the surface energy of the back surface of the impermeable substrate may be adjusted depending on whether or not the back surface of the impermeable substrate is surface treated, and, if so, the conditions for the surface treatment, thereby adjusting the ΔE and ΔE / P ratios.

[0045] The non-permeable substrate may be a transparent non-permeable substrate. Here, "transparent" means that the transmittance of visible light having a wavelength of 400 nm to 700 nm is 80% or more (preferably 90% or more). When the non-permeable substrate is a transparent non-permeable substrate, the image is easily visible through the non-permeable substrate from the back side of the image of the non-permeable substrate. For example, when the non-permeable substrate is a transparent non-permeable substrate, when a colored image, which is a pattern image such as letters or figures, and a white image (e.g., a solid image) as a background image are recorded on the non-permeable substrate in this order as viewed from the non-permeable substrate side, the colored image (e.g., a pattern image such as letters or figures) against the white image (e.g., a solid image) is easily visible through the non-permeable substrate from the back side of the image of the non-permeable substrate.

[0046] In this disclosure, the term "colored" in colored ink and colored pigment means a chromatic color (for example, cyan, magenta, yellow, etc.) or black (hereinafter also referred to as black).

[0047] (White Ink) In the recording process, a white ink is applied to the front surface of the non-permeable substrate by an inkjet method to record a white image.

[0048] The white ink contains water and a white pigment. The white ink will be described below.

[0049] -Water- The white ink contains water. The water content is preferably 10% by mass or more, more preferably 20% by mass or more, even more preferably 30% by mass or more, and particularly preferably 50% by mass or more, relative to the total amount of the white ink. The upper limit of the water content relative to the total amount of the white ink is determined appropriately depending on the contents of other components, but is, for example, 99% by mass, preferably 95% by mass, and more preferably 90% by mass.

[0050] White Pigment The white ink contains a white pigment, such as titanium dioxide, barium sulfate, calcium carbonate, silica, zinc oxide, zinc sulfide, mica, talc, and pearl.

[0051] The white pigment is preferably titanium dioxide, barium sulfate, calcium carbonate, or zinc oxide, more preferably titanium dioxide.

[0052] From the viewpoint of hiding power, the average primary particle diameter of the white pigment is preferably 150 nm or more, more preferably 200 nm or more. From the viewpoint of ink ejection properties, the average primary particle diameter of the white pigment is preferably 400 nm or less, more preferably 350 nm or less. Here, hiding power refers to the ability of the white image to cover and conceal the base on which the white image is formed (for example, the front surface of a non-permeable substrate, or a colored image recorded on the front surface prior to the white image).

[0053] In the present disclosure, the average primary particle diameter of the white pigment is a value measured using a transmission electron microscope (TEM). Specifically, 50 particles of the white pigment are randomly selected within the field of view observed with the TEM, and the primary particle diameters of the 50 particles are measured and averaged. As the transmission electron microscope, a 1200EX transmission electron microscope manufactured by JEOL Ltd. can be used.

[0054] When the ink contains a white pigment, the content of the white pigment is preferably 2% by mass to 25% by mass, more preferably 5% by mass to 25% by mass, and even more preferably 10% by mass to 20% by mass, relative to the total amount of the ink, from the viewpoints of image density and ejection performance.

[0055] Resin The white ink may contain at least one resin. The resin in the white ink contributes to the film-forming properties of the white ink (i.e., the formability of a white ink film).

[0056] The weight average molecular weight (Mw) of the resin is preferably 1,000 to 300,000, more preferably 2,000 to 200,000, and even more preferably 5,000 to 100,000.

[0057] In this disclosure, unless otherwise specified, the weight average molecular weight (Mw) refers to a value measured by gel permeation chromatography (GPC). Measurement by gel permeation chromatography (GPC) is performed using an HLC (registered trademark)-8020GPC (Tosoh Corporation) as a measuring device, three TSKgel (registered trademark) Super Multipore HZ-H columns (4.6 mm ID x 15 cm, Tosoh Corporation), and THF (tetrahydrofuran) as an eluent. The measurement conditions are a sample concentration of 0.45% by mass, a flow rate of 0.35 ml / min, a sample injection amount of 10 μl, and a measurement temperature of 40°C, and the measurement is performed using an RI detector. The calibration curve is prepared from eight samples of "Standard Sample TSK Standard, Polystyrene" from Tosoh Corporation: "F-40", "F-20", "F-4", "F-1", "A-5000", "A-2500", "A-1000", and "n-propylbenzene".

[0058] The resin may be a pigment dispersing resin as a pigment dispersant, or may be resin particles.

[0059] The white ink may contain at least one pigment dispersing resin. The pigment dispersing resin is a resin that has the function of dispersing a pigment. The pigment dispersing resin may be a random copolymer or a block copolymer. The pigment dispersing resin may have a crosslinked structure. The ink may be prepared using a pigment dispersion containing a pigment and a pigment dispersing resin. As the pigment dispersing resin, a known polymer dispersant can be used, such as the polymer dispersants described in paragraphs 0029 to 0106 of WO 2021 / 221069.

[0060] When the white ink contains a pigment dispersion resin, the ratio of the pigment content to the pigment dispersion resin content in the ink, on a mass basis, is preferably from 1:0.04 to 1:3, more preferably from 1:0.05 to 1:1, and even more preferably from 1:0.05 to 1:0.5.

[0061] When the white ink contains a pigment dispersion resin, the content of the pigment dispersion resin relative to the total amount of the ink is preferably 0.1% by mass to 10% by mass, more preferably 0.3% by mass to 5% by mass, and even more preferably 0.5% by mass to 2.5% by mass.

[0062] The white ink may contain at least one type of resin particles.

[0063] The resin constituting the resin particles is preferably a water-insoluble resin. The term "water-insoluble" in the context of a water-insoluble resin means that the amount of the resin that dissolves in 100 g of distilled water at 25°C is less than 2 g.

[0064] The volume average particle size of the resin particles is preferably 1 nm to 300 nm, more preferably 3 nm to 200 nm, and even more preferably 5 nm to 150 nm.

[0065] In the present disclosure, the volume average particle size refers to a value measured using a laser diffraction / scattering particle size distribution analyzer. Examples of the measuring device include a particle size distribution analyzer "Microtrac MT-3300II" (manufactured by Nikkiso Co., Ltd.).

[0066] The resin particles are preferably at least one selected from the group consisting of acrylic resin particles, ester resin particles, a mixture of acrylic resin particles and ester resin particles, composite particles containing an acrylic resin and an ester resin, styrene-acrylic resin particles, and polyurethane resin particles.

[0067] In the present disclosure, acrylic resin refers to a polymer (homopolymer or copolymer) of raw material monomers containing at least one selected from the group consisting of acrylic acid, derivatives of acrylic acid (e.g., acrylic acid esters), methacrylic acid, and derivatives of methacrylic acid (e.g., methacrylic acid esters).

[0068] From the viewpoint of further improving the abrasion resistance of the image, the glass transition temperature (Tg) of the resin particles is preferably 50°C to 250°C, and more preferably 50°C to 150°C. Here, the glass transition temperature (Tg) of the resin particles is a measured Tg obtained by actual measurement. For the method of measuring the measured Tg, see paragraph 0111 of JP2015-25076A.

[0069] For the resin particles, reference may be made to, for example, paragraphs 0038 to 0114 of International Publication No. 2021 / 192720 and paragraphs 0109 to 0120 of JP-A-2015-25076.

[0070] When the white ink contains resin particles, the content of the resin particles in the white ink is preferably 1% by mass to 20% by mass, more preferably 2% by mass to 15% by mass, and even more preferably 2% by mass to 10% by mass, relative to the total amount of the white ink.

[0071] -Water-soluble organic solvent- The white ink preferably contains at least one water-soluble organic solvent. This ensures stable ejection from the inkjet head. The water-soluble organic solvent contained in the white ink may be one type, or two or more types.

[0072] In the present disclosure, the term "water-soluble" in "water-soluble organic solvent" means that 1 g or more of the solvent dissolves in 100 g of water at 25°C.

[0073] The type of water-soluble organic solvent that can be contained in the white ink is not limited, and examples thereof include: monoalcohols having 1 to 4 carbon atoms; diols such as 1,2-ethanediol (also known as ethylene glycol), 1,3-propanediol (also known as propylene glycol), 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, 2-butene-1,4-diol, 2-ethyl-1,3-hexanediol, 2-methyl-2,4-pentanediol, 1,2-octanediol, 1,2-hexanediol, 1,2-pentanediol, and 4-methyl-1,2-pentanediol; triols such as glycerin, 1,2,6-hexanetriol, and trimethylolpropane; alkylene glycol monoalkyl ethers such as ethylene glycol monoalkyl ether and propylene glycol monoalkyl ether; Polyalkylene glycols such as diethylene glycol, triethylene glycol, tetraethylene glycol, pentaethylene glycol, dipropylene glycol, and polyoxyethylene polyoxypropylene glycol; polyalkylene glycol ethers such as diethylene glycol monoalkyl ether, triethylene glycol monoalkyl ether, tripropylene glycol monoalkyl ether, and polyoxypropylene glyceryl ether; 2-pyrrolidone, N-methyl-2-pyrrolidone; and the like.

[0074] From the viewpoint of ejection stability, the water-soluble organic solvent in the white ink preferably contains at least one selected from the group consisting of diols and alkylene glycol monoalkyl ethers.

[0075] The content of the water-soluble organic solvent is preferably 10% by mass to 40% by mass, and more preferably 15% by mass to 30% by mass, relative to the total amount of the white ink.

[0076] -Surfactant- The white ink may contain at least one surfactant, such as a nonionic surfactant, a cationic surfactant, an anionic surfactant, or a betaine surfactant.

[0077] Preferred surfactants include acetylene glycol surfactants, which are a type of nonionic surfactant. Examples of acetylene glycol surfactants that can be used include those described in paragraphs 0070 to 0080 of WO 2017 / 149917. Examples of acetylene glycol surfactants include polyalkylene oxide adducts (preferably polyethylene oxide adducts) of 2,4,7,9-tetramethyl-5-decyne-4,7-diol, polyalkylene oxide adducts (preferably polyethylene oxide adducts) of 3,6-dimethyl-4-octyne-3,6-diol, polyalkylene oxide adducts (preferably polyethylene oxide adducts) of 2,5,8,11-tetramethyl-6-dodecyne-5,8-diol, and polyalkylene oxide adducts (preferably polyethylene oxide adducts) of 2,5-dimethyl-3-hexyne-2,5-diol. Commercially available acetylene glycol surfactants include the Surfynol series (e.g., Surfynol 420, Surfynol 440, Surfynol 465, and Surfynol 485), the Olfin series (e.g., Olfin E1010 and Olfin E1020), and the Dynol series (e.g., Dynol 604) manufactured by Air Products Co., Ltd. or Nissin Chemical Industry Co., Ltd.; and Acetylenol manufactured by Kawaken Fine Chemicals Co., Ltd. Commercially available acetylene glycol surfactants are also provided by The Dow Chemical Company, General Aniline Company, and the like.

[0078] Examples of the surfactant include the compounds listed as surfactants on pages 37 to 38 of JP-A-59-157636 and Research Disclosure No. 308119 (1989).Further examples include fluorine (alkyl fluoride) surfactants and silicone surfactants described in JP-A-2003-322926, JP-A-2004-325707, and JP-A-2004-309806.

[0079] When the white ink contains a surfactant, the content of the surfactant in the white ink is appropriately adjusted in consideration of the surface energy of the white image to be recorded. The content of the surfactant in the white ink is preferably 0.01% by mass to 5% by mass, more preferably 0.05% by mass to 3% by mass, and even more preferably 0.1% by mass to 2% by mass, relative to the total amount of the white ink.

[0080] Other Components The white ink may contain components other than those described above. Examples of other components include known additives such as silicic acid compounds (e.g., the silicic acid compounds described in paragraphs

[0058] to

[0075] of Japanese Patent No. 5,430,316), urea, urea derivatives, wax, anti-fading agents, emulsion stabilizers, penetration enhancers, UV absorbers, preservatives, antifungal agents, pH adjusters, antifoaming agents, viscosity adjusters, dispersion stabilizers, and chelating agents.

[0081] -Physical Properties- From the viewpoint of improving ejection stability, the pH (25°C) of the white ink is preferably 7 to 10, and more preferably 7.5 to 9.5. The pH of the ink can be measured in the same manner as the pH of the pretreatment liquid.

[0082] The viscosity (25°C) of the white ink is preferably 0.5 mPa·s to 30 mPa·s, more preferably 2 mPa·s to 20 mPa·s, preferably 2 mPa·s to 15 mPa·s, and even more preferably 3 mPa·s to 10 mPa·s. The viscosity of the white ink is measured at 25°C using a viscometer, for example, a TV-22 viscometer manufactured by Toki Sangyo Co., Ltd.

[0083] The surface tension (25°C) of the white ink is preferably 60 mN / m or less, more preferably 20 mN / m to 50 mN / m, and even more preferably 25 mN / m to 40 mN / m. The surface tension is measured at 25°C using a surface tensiometer, for example, an automatic surface tensiometer (product name "CBVP-Z" manufactured by Kyowa Interface Science Co., Ltd.) by the plate method.

[0084] (Application of White Ink) In the recording process, a white ink is applied to the front surface of the non-permeable substrate by an inkjet method to record a white image. The method of ejecting the white ink by the inkjet method is not particularly limited, and may be any of known methods, such as a charge control method that uses electrostatic attraction to eject ink, a drop-on-demand method (pressure pulse method) that uses the vibration pressure of a piezoelectric element, an acoustic inkjet method that converts an electric signal into an acoustic beam and irradiates the ink with it to eject the ink by using radiation pressure, and a thermal inkjet (Bubble Jet (registered trademark)) method that heats the ink to form bubbles and uses the resulting pressure.

[0085] As an inkjet recording method, in particular, the method described in JP-A-54-59936 can be effectively used, in which ink subjected to the action of thermal energy undergoes a sudden change in volume, and the ink is ejected from the nozzles by the force caused by this state change. As an inkjet recording method, the method described in paragraphs 0093 to 0105 of JP-A-2003-306623 can also be applied.

[0086] The application of the white ink onto the non-permeable substrate by the inkjet recording method is carried out by ejecting the white ink from the nozzles of an inkjet head.

[0087] Inkjet head methods include the shuttle method, in which a short serial head is scanned across the width of the recording medium to perform recording, and the line method, which uses a line head in which recording elements are arranged to cover the entire area of ​​one side of the recording medium.

[0088] The line method allows for image recording over the entire surface of a recording medium by scanning the recording medium in a direction intersecting the arrangement direction of the recording elements. The line method eliminates the need for a transport system, such as a carriage that scans a short head, as in the shuttle method. Furthermore, compared to the shuttle method, the line method does not require complex scanning control of the carriage movement and the recording medium, and only the recording medium moves. Therefore, the line method achieves faster image recording speeds than the shuttle method.

[0089] The white ink is preferably applied using an inkjet head having a resolution of 300 dpi or more (more preferably 600 dpi or more, and even more preferably 800 dpi or more), where dpi stands for dots per inch, and 1 inch is 2.54 cm.

[0090] From the viewpoint of obtaining a high-definition image, the droplet volume of the white ink is preferably 1 pL (picoliter) to 10 pL, and more preferably 1.5 pL to 6 pL.

[0091] (Drying of White Ink) In the recording step, a white image may be obtained by drying the white ink applied to the front surface of the non-permeable substrate.

[0092] The method for drying the white ink is not particularly limited, and examples thereof include infrared (IR) drying, hot air drying (e.g., a hairdryer), and heat drying using a heating device (e.g., a heater, a hot plate, a heating furnace), etc. The heat drying method may be a combination of two or more of these methods. Heat drying can be performed by heating the white ink from at least one of the front and back sides of the non-permeable substrate.

[0093] The heating temperature for drying the white ink by heating is preferably 35° C. or higher, more preferably 40° C. or higher, even more preferably 50° C. or higher, and even more preferably 60° C. or higher. There is no particular upper limit to the heating temperature, but 100° C. is preferred, and 90° C. is more preferred.

[0094] The heating time for heating and drying the white ink is not particularly limited, but is preferably 1 second to 180 seconds, more preferably 1 second to 120 seconds, and even more preferably 1 second to 60 seconds.

[0095] (Recording of Colored Images) The recording step may further include applying colored inks containing water and color pigments to the front surface of the non-permeable substrate by an inkjet method to record a colored image. According to this embodiment, a multi-color image including a white image and a colored image can be recorded on the front surface of the non-permeable substrate. In this embodiment, only one type of colored ink may be used to record only one type of colored image (e.g., one type of cyan image, magenta image, yellow image, or black image), or two or more types of colored inks may be used to record two or more types of colored images (e.g., two or more types of cyan image, magenta image, yellow image, and black image).

[0096] The colored image may be recorded before or after the white image. An example of a mode in which the colored image is recorded before the white image is a mode in which the colored image (e.g., a pattern image such as letters or graphics) is disposed between the front surface of the non-permeable substrate and the white image (e.g., a solid image). This mode is a mode in which the colored image (e.g., a pattern image such as letters or graphics) is viewed through the non-permeable substrate from the back surface side of the non-permeable substrate against the background of the white image (e.g., a solid image). An example of a mode in which the colored image is recorded after the white image is a mode in which the colored image (e.g., a pattern image such as letters or graphics) is disposed on the white image (e.g., a solid image). This mode is a mode in which the colored image (e.g., a pattern image such as letters or graphics) on the upper layer is viewed against the background of the white image (e.g., a solid image) on the lower layer from the front surface side of the non-permeable substrate.

[0097] From the viewpoint of more effectively suppressing blocking of a multi-color image including a white image and a colored image, a preferred embodiment is one in which the colored image is recorded before the white image and disposed between the front surface of the non-permeable substrate and the white image. In this embodiment, the contact area between the white image and the back surface of the non-permeable substrate is larger than in an embodiment in which the colored image is recorded after the white image and disposed on the white image, and therefore blocking of the multi-color image is more effectively suppressed.

[0098] Color inks used to record color images contain water and color pigments (i.e., chromatic or black pigments). Preferred aspects of the color inks are the same as the preferred aspects of the white ink described above, except for the type of pigment.

[0099] The color pigment may be either an organic pigment or an inorganic pigment that is normally commercially available. Examples of the color pigment include those described in "Pigment Dictionary" edited by Seijiro Ito (published in 2000), "Industrial Organic Pigments" by W. Herbst and K. Hunger, and JP-A Nos. 2002-12607, 2002-188025, 2003-26978, and 2003-342503.

[0100] The color pigment may be a water-insoluble pigment that can be dispersed in water with the aid of a dispersant, or may be a self-dispersing pigment. A self-dispersing pigment is a pigment that can be dispersed in water without the aid of a dispersant. A self-dispersing pigment is a compound in which at least one hydrophilic group selected from the group consisting of a carbonyl group, a hydroxyl group, a carboxyl group, a sulfo group, a phosphate group, and salts thereof is chemically bonded to the surface of the pigment directly or via another group.

[0101] From the viewpoints of the density of the colored image and the ejection properties of the colored ink, the content of the color pigment in the colored ink is preferably 1% by mass to 20% by mass, more preferably 1% by mass to 15% by mass, and even more preferably 1% by mass to 10% by mass, relative to the total amount of the ink.

[0102] <Pretreatment Liquid Application Step> The recording method of the present disclosure may further include, prior to the recording step, a step of applying a pretreatment liquid containing water and a flocculant onto the front surface of the non-permeable substrate (hereinafter also referred to as a "pretreatment liquid application step"). In this case, the recording step involves applying the white ink described above onto the area on the front surface to which the pretreatment liquid has been applied, thereby recording the white image described above. According to an embodiment that includes the pretreatment liquid application step, the components of the white ink are flocculated by the action of the flocculant that has been applied in advance to the front surface, which is advantageous in terms of the image quality of the white image, etc.

[0103] Even in an embodiment that includes a pretreatment liquid application step, the colored image described above may be recorded in addition to the white image. In this case, the colored ink described above is applied to the area on the front surface to which the pretreatment liquid has been applied, to record the colored image. This is advantageous in terms of the image quality of the colored image, as the components of the colored ink are aggregated by the action of the aggregating agent. As described above, the colored image may be recorded on the upper layer side of the white image (the side farther from the non-permeable substrate) or on the lower layer side of the white image (the side closer to the non-permeable substrate; i.e., between the front surface of the non-permeable substrate and the white image).

[0104] (Pretreatment Liquid) The pretreatment liquid contains water and a flocculant.

[0105] -Water- The pretreatment liquid contains water. The water content is preferably 50% by mass or more, and more preferably 60% by mass or more, based on the total amount of the pretreatment liquid. The upper limit of the water content, although it depends on the amounts of other components, is preferably 90% by mass or less, and more preferably 80% by mass or less, based on the total amount of the pretreatment liquid.

[0106] -Aggregating Agent- The pretreatment liquid contains at least one aggregating agent. The aggregating agent in the pretreatment liquid aggregates the components in the ink on the non-permeable substrate. This can improve the image quality. The aggregating agent is preferably at least one selected from the group consisting of organic acids, polyvalent metal compounds, metal complexes, and cationic polymers.

[0107] Preferred examples of the flocculant include the flocculants described in paragraphs 0122 to 0130 of WO 2020 / 195360. Preferred aspects of organic acids, polyvalent metal compounds, metal complexes, and cationic polymers that can be used as flocculants will be described below.

[0108] --Organic Acid-- The organic acid includes an organic compound having an acidic group.

[0109] Acidic groups include phosphate groups, phosphonate groups, phosphinate groups, sulfate groups, sulfonate groups, sulfinate groups, and carboxy groups.

[0110] Among these, from the viewpoint of the aggregation speed of the ink, the acidic group is preferably a phosphate group or a carboxy group, and more preferably a carboxy group.

[0111] It is preferable that at least a portion of the acidic groups is dissociated in the pretreatment liquid.

[0112] Examples of organic compounds having a carboxy group include (meth)acrylic acid, poly(meth)acrylic acid, acetic acid, formic acid, benzoic acid, glycolic acid, malonic acid, malic acid (preferably DL-malic acid), maleic acid, succinic acid, glutaric acid, pimelic acid, adipic acid, fumaric acid, citric acid, tartaric acid, phthalic acid, 4-methylphthalic acid, lactic acid, pyrrolidonecarboxylic acid, pyronecarboxylic acid, pyrrolecarboxylic acid, furancarboxylic acid, pyridinecarboxylic acid, coumaric acid, thiophenecarboxylic acid, and nicotinic acid.

[0113] Among these, from the viewpoint of the aggregation speed of the ink, the organic compound having a carboxy group is preferably a divalent or higher carboxylic acid (hereinafter also referred to as a polycarboxylic acid), and more preferably a dicarboxylic acid.

[0114] Specifically, the polycarboxylic acid is preferably malonic acid, malic acid, maleic acid, succinic acid, glutaric acid, pimelic acid, adipic acid, fumaric acid, tartaric acid, 4-methylphthalic acid, or citric acid, and more preferably malonic acid, malic acid, tartaric acid, succinic acid, glutaric acid, pimelic acid, adipic acid, or citric acid.

[0115] The organic acid preferably has a low pKa (for example, 1.0 to 5.0), which reduces the surface charge of particles such as pigments and resin particles in the ink, which are stabilized by weakly acidic functional groups such as carboxyl groups, by contacting them with an organic acid having an even lower pKa, thereby lowering dispersion stability.

[0116] The organic acid preferably has a low pKa, high solubility in water, and a valence of at least 2. Furthermore, the organic acid more preferably has a high buffering capacity in a pH range lower than the pKa of the functional group (e.g., carboxy group) that stabilizes the dispersion of the particles in the ink.

[0117] --Polyvalent Metal Compound-- Examples of polyvalent metal compounds include polyvalent metal salts. Examples of polyvalent metal salts include organic acid polyvalent metal salts and inorganic acid polyvalent metal salts. Preferred organic acid polyvalent metal salts are polyvalent metal salts of the above-mentioned organic acids (e.g., formic acid, acetic acid, benzoic acid, etc.). Preferred inorganic acid polyvalent metal salts are polyvalent metal nitrates, polyvalent metal hydrochlorides, or polyvalent metal thiocyanates.

[0118] Examples of polyvalent metal salts include salts of alkaline earth metals (e.g., magnesium, calcium) of Group 2 of the periodic table, salts of transition metals (e.g., lanthanum) of Group 3 of the periodic table, salts of metals (e.g., aluminum) of Group 13 of the periodic table, and salts of lanthanides (e.g., neodymium). As the polyvalent metal salt, calcium salts, magnesium salts, or aluminum salts are preferred, and calcium salts or magnesium salts are more preferred.

[0119] The polyvalent metal compound is preferably an organic acid polyvalent metal salt, more preferably an organic acid calcium salt or an organic acid magnesium salt.

[0120] It is preferable that the polyvalent metal compound is at least partially dissociated into polyvalent metal ions and counter ions in the pretreatment liquid.

[0121] --Metal Complex-- The metal complex preferably contains, as a metal element, at least one selected from the group consisting of zirconium, aluminum, and titanium.

[0122] The metal complex is preferably a metal complex containing, as a ligand, at least one selected from the group consisting of acetate, acetylacetonate, methylacetoacetate, ethylacetoacetate, octylene glycolate, butoxyacetylacetonate, lactate, lactate ammonium salt, and triethanolamine.

[0123] The metal complex may be a commercially available product. Various organic ligands, particularly various polydentate ligands capable of forming metal chelate catalysts, are commercially available. Therefore, the metal complex may be a metal complex prepared by combining a commercially available organic ligand with a metal.

[0124] --Cationic Polymer-- The cationic polymer is preferably a homopolymer of a cationic monomer having a primary, secondary, or tertiary amino group or a quaternary ammonium salt group, or a copolymer or condensation polymer of a cationic monomer and a non-cationic monomer. The cationic polymer may be used in the form of either a water-soluble polymer or a water-insoluble polymer (i.e., latex particles). Examples of the cationic polymer include polyvinylpyridine salt, polyalkylaminoethyl acrylate, polyalkylaminoethyl methacrylate, polyvinylimidazole, polyethyleneimine, polybiguanide, polyguanide, polyallylamine, and derivatives thereof.

[0125] The weight-average molecular weight of the cationic polymer is preferably small from the viewpoint of the viscosity of the pretreatment liquid. When the pretreatment liquid is applied to a resin substrate by an inkjet recording method, the weight-average molecular weight is preferably 1,000 to 500,000, more preferably 1,500 to 200,000, and even more preferably 2,000 to 100,000. A weight-average molecular weight of 1,000 or more is advantageous from the viewpoint of aggregation speed. A weight-average molecular weight of 500,000 or less is advantageous from the viewpoint of ejection reliability. However, this does not apply when the pretreatment liquid is applied to a resin substrate by a method other than inkjet recording.

[0126] The content of the flocculant in the pretreatment liquid is preferably 0.1% by mass to 40% by mass, more preferably 0.1% by mass to 30% by mass, even more preferably 1% by mass to 20% by mass, and still more preferably 1% by mass to 10% by mass, relative to the total amount of the pretreatment liquid.

[0127] Resin The pretreatment liquid may contain at least one resin. The resin in the pretreatment liquid contributes to the film-forming properties of the pretreatment liquid (i.e., the film-forming properties of the pretreatment liquid). The resin in the pretreatment liquid may be the same as the resin in the ink (for example, resin particles).

[0128] There are no particular restrictions on the resin content in the pretreatment liquid. The resin content relative to the total amount of the pretreatment liquid is preferably 0.5% by mass to 30% by mass, more preferably 1% by mass to 20% by mass, and particularly preferably 1% by mass to 15% by mass.

[0129] Water-soluble organic solvent The pretreatment liquid may contain at least one water-soluble organic solvent. The water-soluble organic solvent in the pretreatment liquid may be the same as the water-soluble organic solvent that can be contained in the ink.

[0130] -Additives- The ink may contain additives such as surfactants, water-soluble resins, co-sensitizers, ultraviolet absorbers, antioxidants, anti-fading agents, conductive salts, and basic compounds, as needed.

[0131] -Physical Properties- The pH of the pretreatment liquid is preferably 2.0 to 7.0, and more preferably 2.0 to 4.0. The pH of the pretreatment liquid is measured by the same method as that for the pH of the ink.

[0132] From the viewpoint of the coatability of the pretreatment liquid, the viscosity of the pretreatment liquid is preferably 0.5 mPa·s to 10 mPa·s, and more preferably 1 mPa·s to 5 mPa·s. The viscosity is a value measured at 25°C using a viscometer. The viscosity of the pretreatment liquid is measured by the same method as that for the viscosity of the ink.

[0133] The surface tension of the pretreatment liquid is preferably 60 mN / m or less, more preferably 20 mN / m to 50 mN / m, and even more preferably 30 mN / m to 45 mN / m. The surface tension is a value measured at a temperature of 25° C. The surface tension of the pretreatment liquid is measured by the same method as that for measuring the surface tension of the ink.

[0134] (Method of Applying Pretreatment Liquid) The method of applying the pretreatment liquid is not particularly limited, and examples thereof include known methods such as a coating method, a dipping method, and an inkjet recording method.

[0135] Examples of the coating method include known coating methods using a bar coater, extrusion die coater, air doctor coater, blade coater, rod coater, knife coater, squeeze coater, reverse roll coater, and the like.

[0136] (Drying of Pretreatment Liquid) The pretreatment liquid application step may include drying the pretreatment liquid applied to the non-permeable substrate.

[0137] The method for drying the pretreatment liquid is not particularly limited, and for example, the same method as the method exemplified as the method for drying the white ink can be applied. The preferred ranges of the drying conditions (e.g., heating temperature and heating time) for the pretreatment liquid are the same as the preferred ranges of the drying conditions for the white ink.

[0138] <Winding Step> The recording method of the present disclosure includes a winding step of winding up the non-permeable substrate on which a white image has been recorded while applying tension P. The winding step is not particularly limited, and can be carried out using a known winding device including a winding core.

[0139] The recording method of the present disclosure may include other steps in addition to the steps described above.

[0140] <Image Recording Apparatus> The image recording apparatus used in the image recording method of the present disclosure includes: a recording unit that includes an inkjet head for applying the white ink onto one side of the non-permeable substrate and performs a recording step of recording the white image on one side of the non-permeable substrate; and a winding unit that includes a winding device that winds up the non-permeable substrate on which the white image has been recorded while applying tension, and performs the winding step, wherein the ΔE / P ratio is 0.06 to 0.60. The image recording apparatus achieves the same effects as the image recording method of the present disclosure described above.

[0141] 1 is a conceptual diagram illustrating an example of an image recording apparatus used in the image recording method of the present disclosure. As illustrated in Fig. 1, the inkjet recording apparatus according to this example is an example of an inkjet recording apparatus equipped with a transport mechanism for transporting a resin substrate by a roll-to-roll system, in which an unwinding device R1 unwinds a long film-shaped non-permeable substrate A1 wound into a roll, transports the unwound non-permeable substrate A1 in the direction of the block arrow while tension is applied, passes the pretreatment liquid application device P1, the pretreatment liquid drying zone DP1, the first inkjet head IJ1, the first drying zone D1, the second inkjet head IJ2, and the drying zone D2 in this order, and finally, winds the non-permeable substrate A1 by a winding device R2 including a winding core while tension P is applied.

[0142] The impermeable substrate A1 is transported with tension applied and wound up with tension P applied. The tension during transport may be the same as or different from the tension P during winding. Furthermore, the tension may vary depending on the position in the transport direction, or may be uniform. The image recording device according to this example may be equipped with a tension adjusting means for adjusting the tension of the impermeable substrate. Examples of the tension adjusting means include a powder brake provided in the unwinding device R1 and / or the winding device R2, a dancer roll provided along the transport path, and a control device (e.g., a tension controller) that controls each tension by adjusting each condition of the image recording device. The image recording device according to this example may also be equipped with a tension measuring means (e.g., a tension meter) for measuring the tension of the impermeable substrate.

[0143] 1 is a conceptual diagram, the conveyance path of the impermeable substrate A1 is simplified and is shown as if the impermeable substrate A1 is conveyed in one direction, but it goes without saying that in reality the conveyance path of the impermeable substrate A1 may be meandering. As the conveyance method for the impermeable substrate A1, various web conveyance methods such as a cylinder or a roll can be appropriately selected.

[0144] A pretreatment liquid application device P1, a pretreatment liquid drying zone DP1, a first inkjet head IJ1, a first drying zone D1, a second inkjet head IJ2, and a drying zone D2 are arranged downstream in the conveyance direction of the non-permeable substrate A1 relative to an unwinding device R1 that unwinds the non-permeable substrate A1. The pretreatment liquid application device P1, the first inkjet head IJ1, and the second inkjet head IJ2 apply the pretreatment liquid, the first ink, and the second ink, respectively. At this time, at least one of the following may be performed: heat drying of the pretreatment liquid in the pretreatment liquid drying zone DP1, heat drying of the first ink in the first drying zone D1, and heat drying of the second ink in the second drying zone D2. In the first drying zone D1, in addition to heat drying of the first ink, heat drying of the pretreatment liquid may also be performed. In the second drying zone D2, in addition to the heating and drying of the second ink, the pretreatment liquid and / or the first ink may be substantially heated and dried. Furthermore, if the resin substrate passes through each drying zone while the temperature of each drying zone is kept at room temperature, the heating and drying can be omitted.

[0145] In this example, the first ink is either a colored ink containing water and a colored pigment for recording a colored image, or a white ink containing water and a white pigment for recording a white image, and the second ink is the other of the colored ink and the white ink.

[0146] A surface treatment section (not shown) for performing surface treatment (preferably corona treatment) on at least one of the front surface and the back surface of the non-permeable substrate A1 may be provided upstream of the pretreatment liquid application device P1. In addition, a cooling zone for cooling the recorded multi-color image (i.e., the multi-color image including the white image and the colored image) may be provided downstream of the second drying zone D2.

[0147] The first inkjet head IJ1 and the second inkjet head IJ2 may be shuttle heads, but from the viewpoint of increasing the image recording speed, line heads in which a large number of ejection openings (nozzles) are arranged across the width of the non-permeable substrate A1 in the form of a long film are preferred. The first inkjet head IJ1 and the second inkjet head IJ2 may each be a single head or multiple heads. An example of a combination of the first inkjet head IJ1 and the second inkjet head IJ2 is a combination in which the first inkjet head IJ1 is four inkjet heads corresponding to four colors, cyan, magenta, yellow, and black (note: these four inkjet heads are arranged in the transport direction of the resin substrate), and the second inkjet head IJ2 is one inkjet head corresponding to white (i.e., white). Another example of a combination of the first inkjet head IJ1 and the second inkjet head IJ2 is a combination in which the first inkjet head IJ1 is one inkjet head corresponding to white (i.e., white), and the second inkjet head IJ2 is four inkjet heads corresponding to four colors, cyan, magenta, yellow, and black (note: these four inkjet heads are arranged in the transport direction of the resin substrate).

[0148] Inkjet recording using the image recording apparatus according to this example involves: first, unwinding a long film-shaped non-permeable substrate A1 wound into a roll by an unwinding device R1; transporting the unwound non-permeable substrate A1 in the direction of the block arrow while tension is applied; applying a pretreatment liquid to the transported non-permeable substrate A1 by a pretreatment liquid application device P1; drying the pretreatment liquid in a pretreatment liquid drying zone DP1 as needed; applying a first ink (i.e., either a colored ink or a white ink) by a first inkjet head IJ1; drying the first ink as needed in a first drying zone D1; applying a second ink (i.e., the other of the colored ink and the white ink) by a second inkjet head IJ2; drying the second ink as needed in a second drying zone D2. This results in a multi-color image including a first image derived from the first ink (i.e., either a colored image or a white image) and a second image derived from the second ink (i.e., the other of the colored image and the white image). Next, if necessary, the obtained multi-color image is cooled, and finally, the non-permeable substrate A1 with the multi-color image thereon is wound up by a winding device R2 including a winding core, with tension P applied thereto.

[0149] In this example, the surface energy difference ΔE (mJ / m) between the back surface of the non-permeable substrate A1 and the front surface of the white image is ２ ) divided by the tension P (N / m), which is the tension just before the winding device R2, is adjusted so that the ΔE / P ratio is 0.06 to 0.60. This suppresses winding slippage and white image blocking in the non-permeable substrate A1 after winding. In this case, in an embodiment where the first image is a colored image and the second image is a white image (i.e., the colored image is recorded before the white image) and the colored image is disposed between the non-permeable substrate and the white image, the white image is on the upper layer side, so the entire surface of the white image contacts the back surface of the non-permeable substrate. This increases the contact area between the white image and the back surface of the non-permeable substrate, resulting in a more effective suppression of multi-color image blocking compared to when the colored image is on the upper layer side.

[0150] In this example, the application and drying of the pretreatment liquid may be omitted. Also, in this example, a white image alone may be recorded without recording a colored image.

[0151] Examples of the present disclosure will be described below, but the present disclosure is not limited to the following examples.

[0152] <Preparation of Pretreatment Liquid> The components shown below were mixed to prepare a pretreatment liquid.

[0153] - Composition of pretreatment liquid - Glutaric acid (flocculant) ... 6.1 mass % Propylene glycol (PG) [water-soluble organic solvent] ... 20 mass % Olfine E1010 (manufactured by Nissin Chemical Co., Ltd.) [surfactant] ... 0.5 mass % Superflex 500M (Dai-ichi Kogyo Seiyaku) [aqueous dispersion of urethane resin particles] ... 7.0 mass % Triisopropanolamine (pH adjuster) ... 0.2 mass % BYK024 (BYK Corporation) [defoaming agent] ... 0.01 mass % Ultrapure water ... the balance to make the total pretreatment liquid 100 mass %

[0154] <Preparation of White Ink W1> The components shown below were mixed to prepare White Ink W1.

[0155] -Composition of White Ink W1- -White pigment dispersion as follows: ... 12% by mass as white pigment content -Propylene glycol (PG) [water-soluble organic solvent] ... 28% by mass -Propylene glycol monomethyl ether (PGmME) [water-soluble organic solvent] ... 2% by mass -Olfine E1010 (manufactured by Nissin Chemical Industry Co., Ltd.) [acetylene glycol-based surfactant] ... 0.60% by mass -Solsperse 43000 (manufactured by The Lubrizol Corporation Japan) [water-soluble polymer] ... 1% by mass -PVP-K15 (polyvinylpyrrolidone K15) ... 0.12% by mass -Urea ... 0.50% by mass -Snowtex XS (manufactured by Nissan Chemical Industries, Ltd.) [colloidal silica dispersion] ... 0.1% by mass as colloidal silica particle content -Neocryl A1091 (manufactured by Covestro Coating Resins) [aqueous dispersion of styrene acrylic resin particles] Styrene acrylic resin particle content: 5.0% by mass Water: The remaining amount that makes the entire white ink 100% by mass

[0156] (Preparation of White Pigment Dispersion) - Synthesis of Pigment Dispersant P1 - 965 g of dipropylene glycol was added to a 5000 mL three-neck flask equipped with a stirrer and a condenser, and the mixture was heated to 85°C under a nitrogen atmosphere. Solution I was obtained by dissolving 640 g of benzyl methacrylate, 340 g of methacrylic acid, and 19.94 g of 2-mercaptopropionic acid in 370.28 g of dipropylene glycol, and Solution II was obtained by dissolving 17.69 g of t-butylperoxy-2-ethylhexanoate (product name "Perbutyl O", manufactured by NOF Chemical Industries, Ltd.) in 221.17 g of dipropylene glycol, to prepare the following solutions. Solution I was added dropwise to the three-neck flask over 4 hours, and Solution II was added dropwise over 5 hours. After the completion of the dropwise addition, the mixture was allowed to react for an additional 2 hours. The disappearance of the monomer was １ The reaction mixture was heated to 70°C, and 248.02 g of a 50% by mass aqueous solution of potassium hydroxide was added thereto. Then, 107.48 g of dipropylene glycol and 75.52 g of pure water were added thereto and stirred to obtain a 37% by mass solution of a random polymer. This random polymer was designated as pigment dispersant P1. The structural units constituting the obtained random polymer were １ The polymer was confirmed by H-NMR. The weight average molecular weight (Mw) was determined by GPC. The weight average molecular weight (Mw) of the obtained pigment dispersant P1 was 8,400, and the acid value was 221.7 mgKOH / g.

[0157] - Preparation of White Pigment Dispersion - Pigment dispersant P1 (150 parts by mass) was dissolved in water to prepare a polymer solution with a pigment dispersant P1 concentration of 25% by mass. 96 parts by mass of the above polymer solution, 300 parts by mass of a white pigment, C.I. Pigment White 6 (trade name "JR-405", titanium dioxide particles, manufactured by Teica Corporation), and 270 parts by mass of water were mixed to obtain a mixed solution. A potassium hydroxide aqueous solution was added to the obtained mixed solution, and the pH after neutralization was adjusted to 8.7. Next, the neutralized mixed solution was subjected to a dispersion treatment for 3 hours using a bead mill (bead diameter: 0.1 mmφ, zirconia beads). This resulted in a white pigment dispersion (uncrosslinked dispersion) PD1 in which the white pigment was dispersed using pigment dispersant P1. Next, the obtained white pigment dispersion (uncrosslinked dispersion) PD1 was subjected to ultrafiltration using an ultrafiltration device (crossflow type ultrafilter (UF), manufactured by Sartorius) by flowing ion-exchanged water at a flow rate of 600 mL per minute. The liquid temperature was maintained at 25 ° C., and ultrafiltration was performed three times, with one run being 1 times the volume of the charged liquid. Ion-exchanged water was added to the liquid after ultrafiltration to obtain a post-ultrafiltration dispersion having a white pigment concentration of 45% by mass and a pigment dispersant P1 concentration of 3.6% by mass. To 136 parts by mass of the above post-ultrafiltration dispersion, 1.35 parts by mass of trimethylolpropane polyglycidyl ether (product name "Denacol EX-321", manufactured by Nagase ChemteX Corporation) as a crosslinking agent, and 14.5 parts by mass of an aqueous boric acid solution (boric acid concentration: 4% by mass) were added, and the mixture was reacted at 70 ° C. for 6 hours, and then cooled to 25 ° C. This crosslinked the pigment dispersant P1 in the dispersion to form a pigment dispersant P1a, a crosslinked polymer dispersant, and obtained a white pigment dispersion (crosslinked dispersion) in which the white pigment was dispersed by the pigment dispersant P1a. Ion-exchanged water was added to the resulting crosslinked dispersion so that the pigment concentration was 15% by mass. The crosslinked dispersion to which ion-exchanged water had been added was passed through an ultrafiltration device (crossflow ultrafilter (UF), manufactured by Sartorius) equipped with a polyethersulfone (PESU) membrane (micropore size: 0.1 μm) at a flow rate of 600 mL per minute to perform ultrafiltration. The liquid temperature was adjusted to 25°C, and ultrafiltration was performed three times, with each run being 1x the volumetric ratio of the liquid charged.Next, ion-exchanged water was added to the white pigment dispersion to adjust the white pigment concentration to 45% by mass. This resulted in a white pigment dispersion. The acid value of the pigment dispersant P1a contained in the white pigment dispersion was 144 mg KOH / g. The concentration of the pigment dispersant P1a was 3.6% by mass.

[0158] <White Inks W2 to W7> White inks W2 to W7 were each prepared in the same manner as white ink W1, except that the ink composition was changed as shown in Table 1 below. In preparing white inks W2 to W7, the same white pigment dispersion liquid as used in preparing white ink W1 was used. Note that blank cells in Table 1 indicate that the corresponding component was not contained.

[0159] <Preparation of Cyan Ink C1> Cyan ink C1 was prepared in the same manner as for the preparation of white ink W1, except that the ink composition was changed as shown in the following Table 1. In preparing cyan ink C1, APD4000 Cyan (manufactured by Fujifilm Imaging Colorants Ltd.) was used as the cyan pigment dispersion instead of the white pigment dispersion.

[0160]

[0161] -Details of the components in Table 1- White pigment: the white pigment in the white pigment dispersion described above Cyan pigment: the cyan pigment in APD4000 Cyan (manufactured by Fujifilm Imaging Colorants Ltd.), which is a cyan pigment dispersion PG: propylene glycol (water-soluble organic solvent) PGmME: propylene glycol monomethyl ether (water-soluble organic solvent) DEGmBE: diethylene glycol monobutyl ether (water-soluble organic solvent) Olfine E1010: an acetylene glycol-based surfactant manufactured by Nissin Chemical Industry Co., Ltd. Surfynol 104P: an acetylene glycol-based surfactant manufactured by Nissin Chemical Industry Co., Ltd. BYK-347: a silicone-based surfactant manufactured by BYK Corporation Solsperse 43000: a water-soluble polymer manufactured by The Lubrizol Corporation Japan PVP-K15: polyvinylpyrrolidone K15. Snowtex XS: Colloidal silica dispersion manufactured by Nissan Chemical Industries, Ltd. The contents in Table 1 are the contents as solids (colloidal silica particles). Superflex: Superflex 460: Aqueous dispersion of urethane resin particles manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd. The contents in Table 1 are the contents as solids (resin particles). Neocryl A1091: Aqueous dispersion of styrene acrylic resin particles manufactured by Covestro Coating Resins. The contents in Table 1 are the contents as solids (resin particles).

[0162] <Preparation of Image Recording Apparatus> The image recording apparatus used for evaluation was the one shown in Fig. 1 according to the above-described example. A gravure coater was used as the pretreatment liquid application device P1. Hot air drying was used as the drying method in the pretreatment liquid drying zone DP1.

[0163] An inkjet head for cyan was arranged as the first inkjet head IJ1. An inkjet head for white was arranged as the second inkjet head IJ2. The inkjet heads and ink ejection conditions were as follows: Inkjet head: A 1200 dpi (dots per inch, 1 inch is 2.54 cm) / 20 inch wide piezo full line head (total number of nozzles: 2048) was used. Ink droplet volume: 2.0 pL. Driving frequency: 30 kHz.

[0164] The drying method in both the first drying zone D1 and the second drying zone D2 was hot air drying. An air cooling zone (not shown) was provided between the second drying zone D2 and the winding device R2.

[0165] A tension controller ("LE-40MTA" manufactured by Mitsubishi Electric Corporation) was installed in the inkjet recording apparatus, and this was used to control the tension applied to the non-permeable substrate (particularly the tension P in the winding section described later) during inkjet recording described later.

[0166] <Preparation of Impermeable Substrates> The following impermeable substrates were prepared as the impermeable substrates used for evaluation. In each of the examples and comparative examples described below, one of the following impermeable substrates was used (see Table 2 for details). P2161: OPP film "Pylen Film-OT" manufactured by Toyobo Co., Ltd., 25 μm or 40 μm thick. PET: PET film "Taiko Polyester Film FE2001" manufactured by Futamura Chemical Co., Ltd., 12 μm, 25 μm, or 50 μm thick. Backside-treated PET: PET film "Taiko Polyester Film FE2001" (12 μm thick) manufactured by Futamura Chemical Co., Ltd., with the backside corona-treated. The corona treatment was performed using a corona treatment device "Corona Master PS-10S" manufactured by Shinko Electric Meter Co., Ltd., at a treatment voltage of 15 kV and a treatment speed of 100 mm / s.・FOR-AQ... OPP film "Taiko Polypropylene Film" manufactured by Futamura Chemical Co., Ltd. Thickness: 25 μm. ・Nylon... Nylon film "ON-25" manufactured by Unitika Ltd. Thickness: 25 μm.

[0167] [Example 1] <Image Recording> Using the above image recording device, a non-permeable substrate (P2161, thickness 25 μm), the above pretreatment liquid, and the above white ink W1, inkjet recording was carried out as follows to obtain an imaged substrate. In Example 1, cyan ink was not used, and treatment with the first inkjet head IJ1 and the first drying zone D1 was not carried out.

[0168] First, the non-permeable substrate was unwound by the unwinding device R1. The unwound non-permeable substrate was transported under tension. A pretreatment liquid was applied to the transported non-permeable substrate by a gravure coater serving as a pretreatment liquid application device P1. The pretreatment liquid was then dried in the pretreatment liquid drying zone DP1. The non-permeable substrate then passed through the first inkjet head IJ1 and the first drying zone D1. Next, a white ink W1 was applied in the form of a solid image by the second inkjet head IJ2 to the area of ​​the non-permeable substrate to which the pretreatment liquid had been applied. The white ink W1 was then dried in the second drying zone D2. Through these operations, a white image (solid image) derived from the white ink W1 was recorded on the transported non-permeable substrate, thereby obtaining an imaged substrate. The obtained imaged substrate was then air-cooled and then wound up by a winding device R2 including a winding core, obtaining a roll of the imaged substrate.

[0169] In the image recording, the conveying speed of the non-permeable substrate was adjusted to 70 m / min, and the tension P of the non-permeable substrate within a distance of 1 m from the winding device R2 (hereinafter also referred to as "tension P at the winding section") was adjusted to the value shown in Table 2. The tension P (N / m) at the winding section was measured using a tension meter. The amount of pretreatment liquid applied was 1.7 g / m. ２ The amount of white ink applied was 3.8 g / m ２ The drying conditions for the pretreatment liquid were 40° C. and 3 seconds, and the drying conditions for the white ink were 70° C. and 20 seconds (hereinafter, these drying conditions are referred to as “control”).

[0170] <Measurement of Surface Energy and Calculation of Surface Energy Difference ΔE> Immediately before the start of the image recording (specifically, at least one hour before the start of the image recording), the surface energy (i.e., the dispersion component γ Ｓ ｄ , hydrogen bond component γ Ｓ ｈ , and the surface energy γ Ｓ After the image recording (specifically, within one hour after winding), the roll of the image-bearing substrate was unwound, and the surface energy (i.e., the dispersion component γ Ｓ ｄ , hydrogen bond component γ Ｓ ｈ , and the surface energy γ Ｓ ) was measured by the method described above. Based on the above measurement results, the surface energy difference ΔE (mJ / m ２ The results are shown in Table 2.

[0171] <Calculation of ΔE / P ratio> The ΔE / P ratio was calculated based on the surface energy difference ΔE and the tension P of the winding portion. The results are shown in Table 2.

[0172] <Evaluation> An image was recorded on a 1000 m long non-permeable substrate by the above image recording method, to obtain a roll of the non-permeable substrate having an image thereon. The obtained roll of the non-permeable substrate was used to perform the following evaluations. The results are shown in Table 2.

[0173] (Blocking of White Image) The roll of the image-bearing substrate was unwound, and the blocking of the white image was evaluated at a position approximately 100 m from the end of the winding according to the following evaluation criteria: In the following evaluation criteria, the rank AA indicates that the blocking of the white image is most suppressed.

[0174] -Evaluation criteria for white image blocking- AA: At a position approximately 100 m from the end of winding, no peeling sound due to unwinding was heard and no transferred material was found on the back surface of the non-permeable substrate. A: At a position approximately 100 m from the end of winding, peeling sound due to unwinding was sometimes heard, but no transferred material was found on the back surface of the non-permeable substrate. B: At a position approximately 100 m from the end of winding, peeling sound due to unwinding was heard continuously, but no transferred material was found on the back surface of the non-permeable substrate. C: At a position approximately 100 m from the end of winding, a colorless and transparent transferred material was found on the back surface of the non-permeable substrate. D: At a position approximately 100 m from the end of winding, a transferred white image was found on the back surface of the non-permeable substrate.

[0175] (Wound slippage of non-permeable substrate) The roll of image-bearing substrate used in the evaluation of white image blocking was observed, and the maximum distance (amount of slippage) between the axial end of the winding core and the widthwise end of the non-permeable substrate was measured, and the measurement result was taken as the amount of winding slippage of the non-permeable substrate. Based on the amount of winding slippage of the non-permeable substrate, the winding slippage of the non-permeable substrate was evaluated according to the following evaluation criteria. In the following evaluation criteria, the rank AA represents the most suppressed winding slippage of the non-permeable substrate.

[0176] - Evaluation criteria for winding slippage of impermeable substrate - AA: The amount of winding slippage of the impermeable substrate was less than 0.5 mm. A: The amount of winding slippage of the impermeable substrate was 0.5 mm or more and less than 1.0 mm. B: The amount of winding slippage of the impermeable substrate was 1.0 mm or more and less than 2.0 mm. C: The amount of winding slippage of the impermeable substrate was 2.0 mm or more and less than 3.0 mm. D: The amount of winding slippage of the impermeable substrate was 3.0 mm or more.

[0177] Examples 2 to 7, 9 to 12 The same operation as in Example 1 was carried out, except that at least one of the type of white ink, the drying conditions for the white ink, the type of non-permeable substrate, the thickness of the non-permeable substrate, and the tension P of the winding section was changed as shown in Table 2. The results are shown in Table 2.

[0178] Regarding the drying conditions for the white ink, "strong drying" means drying conditions of 75°C for 20 seconds, and "weak drying" means drying conditions of 65°C for 20 seconds.

[0179] The same operations as in Example 2 were carried out, except that, between the drying of the pretreatment liquid and the application of the white ink, the application of the cyan ink C1 by the first inkjet head IJ1 and the drying of the cyan ink C1 in the first drying zone D1 were added. The results are shown in Table 2.

[0180] In Example 8, the cyan ink C1 was applied in a solid image on the area of ​​the non-permeable substrate where the pretreatment liquid had been applied, and the white ink W1 was applied in a solid image on top of the cyan ink C1 applied to the above area (i.e., on top of the cyan solid image). The drying conditions for the cyan ink C1 were 70°C and 20 seconds (i.e., "control").

[0181] Comparative Examples 1 to 5 The same operations as in Example 1 were carried out, except that at least one of the type of white ink, the drying conditions for the white ink, the type of non-permeable substrate, the thickness of the non-permeable substrate, and the tension P of the winding section was changed as shown in Table 2. The results are shown in Table 2.

[0182]

[0183] As shown in Table 2, in Examples 1 to 12, in which the ΔE / P ratio was 0.06 to 0.60, blocking of the white image and winding slippage of the non-permeable substrate were suppressed. In contrast, in Comparative Examples 2 to 4, in which the ΔE / P ratio was less than 0.06, blocking of the white image could not be suppressed. Furthermore, in Comparative Examples 1 and 5, in which the ΔE / P ratio was greater than 0.60, blocking of the white image could be suppressed, but winding slippage of the non-permeable substrate could not be suppressed.

[0184] The results of Examples 1, 5, 11, and 12 show that when ΔE is 5.0 to 25.0 (Examples 1 and 5), the winding slippage of the impermeable substrate is further suppressed.

[0185] The results of Examples 1, 6, 7, and 10 show that when P is 30 to 150 (Examples 1, 6, and 10), winding slippage of the impermeable substrate is further suppressed.

[0186] The results of Examples 1 to 12 show that when the ΔE / P ratio is 0.10 or more (Examples 2 to 9, 11, and 12), blocking of the white image is further suppressed.The results of Examples 1 to 12 show that when the ΔE / P ratio is 0.50 or less (Examples 1 to 6 and 8 to 11), winding slippage of the non-permeable substrate is further suppressed.

[0187] [Modification of Example 8] The same procedure as in Example 8 was carried out, except that the cyan ink C1 in Example 8 was replaced with magenta ink M1 prepared as follows (modification of Example 8). As a result, evaluation results similar to those in Example 8 were obtained in this modification.

[0188] <Preparation of Magenta Ink M1> Magenta ink M1 was prepared in the same manner as for the preparation of cyan ink C1, except that the cyan pigment dispersion (APD4000 Cyan; manufactured by Fujifilm Imaging Colorants Ltd.) used in the preparation of cyan ink C1 was changed to APD4000 Magenta (manufactured by Fujifilm Imaging Colorants Ltd.) and APD1000 Red (manufactured by Fujifilm Imaging Colorants Ltd.) as magenta pigment dispersions. In this case, the amounts of APD4000 Magenta and APD1000 Red used were adjusted so that the pigment content in APD4000 Magenta relative to the total amount of magenta ink M1 was 4.9 mass %, and the pigment content in APD1000 Red relative to the total amount of magenta ink M1 was 1.6 mass %.

[0189] Although the examples described above show the application of a pretreatment liquid before the application of a white ink, the application of the pretreatment liquid may be omitted. Even when the application of the pretreatment liquid is omitted and a white image is recorded on the non-permeable substrate directly or via a colored image, the effects of suppressing blocking of the white image and suppressing misalignment of the non-permeable substrate when wound are obtained, similar to the examples described above.

[0190] The disclosure of Japanese Patent Application No. 2022-122181, filed on July 29, 2022, is incorporated herein by reference in its entirety. All documents, patent applications, and technical standards described herein are incorporated herein by reference to the same extent as if each individual document, patent application, and technical standard was specifically and individually indicated to be incorporated by reference.

Claims

1. a recording step of applying a white ink containing water and a white pigment onto one surface of a non-permeable substrate by an inkjet method to record a white image; a winding step of winding up the non-permeable substrate on which the white image is recorded while applying tension; Including, a ΔE / P ratio, which is a value obtained by dividing ΔE by P, is 0.06 to 0.60, where ΔE is a surface energy difference in mJ / m2 between the other surface of the non-permeable substrate and the surface of the white image, and P is the tension in N / m; Image recording method.

2. the recording step further includes applying a color ink containing water and a color pigment onto the one surface of the non-permeable substrate by an inkjet method to record a color image; The image recording method according to claim 1 .

3. the colored image is recorded before the white image and is disposed between the one side of the non-permeable substrate and the white image; The image recording method according to claim 2 .

4. 4. The image recording method according to claim 1, wherein the ΔE is from 5.0 to 25.

0.

5. The image recording method according to any one of claims 1 to 3, wherein P is 30 to 150.

6. 4. The image recording method according to claim 1, wherein the ΔE / P ratio is from 0.10 to 0.

50.

7. The method further includes, before the recording step, a step of applying a pretreatment liquid containing water and a coagulant onto the one surface of the non-permeable substrate, the recording step includes applying the white ink onto the area on the one surface to which the pretreatment liquid has been applied, thereby recording the white image; The image recording method according to any one of claims 1 to 3.

8. The image recording method according to any one of claims 1 to 3, a recording unit including an inkjet head for applying the white ink onto one surface of the non-permeable substrate, the recording unit performing a recording step of recording the white image on the one surface of the non-permeable substrate; a winding section that performs the winding step, the winding section including a winding device that winds up the non-permeable base material on which the white image is recorded in a state where tension is applied; Including, The ΔE / P ratio is 0.06 to 0.60; Image recording device.