Image recording method

Abstract

An image recording method includes the steps of: applying an ink containing water to an impermeable substrate; the non-permeable base material to which the ink is applied is conveyed using a conveying member having a concave-convex shape on the surface. And heating the non-permeable substrate, and when the amount of ink applied per unit area of the non-permeable substrate is V (g / m < 2 >), the thickness of the non-permeable substrate is t ([mu] m), and the width of one of the concave portions and the convex portions of the transport member, which has a smaller surface area, is A ([mu] m), V, t, and A satisfy the following formula (1). 10 < = (V / t) * A < = 4000... (1)

Description

Technical Field

[0001] The present invention relates to an image recording method. Background Art

[0002] Hitherto, various studies have been made on image recording methods.

[0003] For example, Japanese Patent Application Laid-Open No. 2010-208207 discloses an image recording apparatus including: a conveying device including a belt main body that mounts a medium and conveys it, and a functional layer provided on the mounting surface side of the belt main body and having a concavo-convex pattern, the concavo-convex pattern including a plurality of convex portions extending in one direction and arranged substantially parallel to each other and concave portions provided between the plurality of convex portions, a conveyor belt in which the convex portions extend in a direction non-orthogonal to the circumferential direction of the belt main body; and a recording head that ejects ink droplets onto the medium conveyed by the conveying device. Summary of the Invention

[0004] Technical Problem to be Solved by the Invention

[0005] However, when a non-permeable substrate to which ink is applied is conveyed using a conveying member having a concavo-convex surface, unevenness sometimes occurs in the image recorded on the non-permeable substrate. Therefore, it is required to maintain the conveyability when using a conveying member having a concavo-convex surface and suppress the unevenness of the recorded image.

[0006] The present invention has been made in view of such circumstances, and an object of one embodiment of the present invention is to provide an image recording method having excellent conveyability of a non-permeable substrate and capable of suppressing unevenness of a recorded image.

[0007] Means for Solving the Technical Problem

[0008] The present invention includes the following aspects.

[0009] <1>

[0010] An image recording method including the following steps:

[0011] Applying an ink containing water onto a non-permeable substrate;

[0012] Using a conveying member having a concavo-convex shape on the surface to convey the non-permeable substrate to which the ink is applied; and

[0013] Heating the non-permeable substrate,

[0014] When the application amount of the ink per unit area with respect to the non-permeable substrate is set to V (g / m 2) When the thickness of the non-permeable substrate is set to t (μm) and the width of the one with the smaller surface area among the concave and convex portions of the conveying member is set to A (μm), V, t, and A satisfy the following formula (1).

[0015] 10 ≤ (V / t) × A ≤ 4000…(1)

[0016] <2>

[0017] According to the image recording method described in <1>, wherein

[0018] V, t, and A satisfy the following formula (2).

[0019] 10 ≤ (V / t) × A ≤ 2000…(2)

[0020] <3>

[0021] According to the image recording method described in <1>, wherein

[0022] V, t, and A satisfy the following formula (3).

[0023] 10 ≤ (V / t) × A ≤ 1000…(3)

[0024] <4>

[0025] According to the image recording method described in any one of <1> to <3>, wherein

[0026] When the surface free energy of the non-permeable substrate is set to E1 (mN / m), the surface tension of the ink is set to E2 (mN / m), and the value obtained by subtracting E2 from E1 is set to ΔE, the following formula (4) is satisfied.

[0027] △E / E2 ≤ 0.50…(4)

[0028] <5>

[0029] According to the image recording method described in any one of <1> to <4>, wherein

[0030] When the surface free energy of the non-permeable substrate is set to E1 (mN / m), the surface tension of the ink is set to E2 (mN / m), and the value obtained by subtracting E2 from E1 is set to ΔE, the following formula (5) is satisfied.

[0031] 4 ≤ (V / t) × A × (△E / E2) ≤ 1200…(5)

[0032] <6>

[0033] According to the image recording method described in any one of <1> to <5>, wherein

[0034] In the conveying member, when the surface area of the larger one of the surface area of the concave portion and the surface area of the convex portion is set as T A and the surface area of the smaller one is set as T B the following formula (6) is satisfied.

[0035] 0.08 ≤ T B / T A ≤ 0.6…(6)

[0036] <7>

[0037] According to the image recording method according to any one of <1> to <6>, wherein

[0038] the ink contains water and a white pigment.

[0039] <8>

[0040] According to the image recording method according to any one of <1> to <7>, wherein

[0041] the step of applying the ink includes the following steps:

[0042] applying a first ink containing water and a flocculant on a non-permeable substrate; and

[0043] applying a second ink containing water and a pigment on the non-permeable substrate on which the first ink has been applied,

[0044] In the conveying step, a conveying member is used to convey the first ink,

[0045] When the application amount of the first ink per unit area of the non-permeable substrate is set as V, V, t, and A satisfy formula (1).

[0046] Advantageous Effects of the Invention

[0047] According to an embodiment of the present invention, there is provided an image recording method that has excellent transportability of a non-permeable substrate and can suppress unevenness of a recorded image. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Figure 1 is a diagram conceptually showing a first specific example of an image recording apparatus used in the image recording method of the present invention.

[0049] Figure 2 is a diagram conceptually showing a second specific example of an image recording apparatus used in the image recording method of the present invention.

[0050] Figure 3A is a diagram showing an example of a conveying member used in the image recording method of the present invention.

[0051] Figure 3BThis is a diagram showing an example of a conveying member used in the image recording method of the present invention.

[0052] Figure 3C This is a diagram showing an example of a conveying member used in the image recording method of the present invention.

[0053] Figure 4A This is a diagram for explaining a method of calculating the surface areas of the concave and convex portions.

[0054] Figure 4B This is a diagram for explaining a method of calculating the surface areas of the concave and convex portions.

[0055] Figure 4C This is a diagram for explaining a method of calculating the surface areas of the concave and convex portions.

[0056] Figure 4D This is a diagram for explaining a method of calculating the surface areas of the concave and convex portions.

[0057] Figure 4E This is a diagram for explaining a method of calculating the surface areas of the concave and convex portions.

[0058] Figure 4F This is a diagram for explaining a method of calculating the surface areas of the concave and convex portions.

[0059] Figure 4G This is a diagram for explaining a method of calculating the surface areas of the concave and convex portions. Detailed Description of the Invention

[0060] In the present invention, a numerical range represented by "~" means a range including the numerical values described before and after "~" as the minimum value and the maximum value, respectively.

[0061] In the numerical ranges described stepwise in this specification, the upper limit value or the lower limit value described in a certain numerical range can be replaced with the upper limit value or the lower limit value of another numerically described range. Moreover, within the numerical ranges described in this specification, the upper limit value or the lower limit value described in a certain numerical range can also be replaced with the value shown in the examples.

[0062] In the present invention, when there are a plurality of substances corresponding to each component in the composition, unless otherwise specified, the amount of each component in the composition represents the total amount of the plurality of substances present in the composition.

[0063] In the present invention, a combination of two or more preferred modes is a more preferred mode.

[0064] In the present invention, the term "step" includes not only an independent step, but also includes this term even when it cannot be clearly distinguished from other steps as long as the purpose expected by the step can be achieved.

[0065] In the present invention, "ink" refers to a liquid applied to a non-permeable substrate. The concept of "ink" in the present invention includes not only liquids that exhibit specific colors but also colorless and transparent liquids. Generally, a pretreatment liquid applied to a non-permeable substrate before the application of a coloring ink is also a form of ink.

[0066] In the present invention, "image" refers to the ink film itself in the case of using one kind of ink, and refers to a laminated film of multiple ink films in the case of overlapping use of multiple inks.

[0067] In the present invention, "image recording" refers to the formation of an image.

[0068] The concept of "image" in the present invention also includes a solid image.

[0069] In the present invention, unless otherwise specifically stated, "upstream side" refers to the upstream side in the conveyance direction of the non-permeable substrate, and unless otherwise specifically stated, "downstream side" refers to the downstream side in the conveyance direction of the non-permeable substrate.

[0070] [Image Recording Method]

[0071] The image recording method of the present invention includes the following steps: applying an ink containing water to a non-permeable substrate (hereinafter, also referred to as "ink application step"); conveying the non-permeable substrate to which the ink has been applied using a conveying member having an uneven surface (hereinafter, also referred to as "conveying step"); and heating the non-permeable substrate (hereinafter, also referred to as "heating step"). When the application amount of the ink per unit area of the non-permeable substrate is set to V (g / m 2 ), the thickness of the non-permeable substrate is set to t (μm), and the width of the smaller one of the concave and convex portions of the conveying member is set to A (μm), V, t, and A satisfy the following formula (1).

[0072] 10 ≤ (V / t) × A ≤ 4000…(1)

[0073] The image recording method of the present invention may include other steps other than the above-described ink application step, conveying step, and heating step as needed.

[0074] According to the image recording method of the present invention, the conveyance property of the non-permeable substrate is excellent, and unevenness of the recorded image can be suppressed.

[0075] This effect is exerted by the above V, the above t, and the above A satisfying the above formula (1).

[0076] Conventionally, in the case of recording an image on a non-permeable substrate, if a conveying member having a concavo-convex surface is used, it is possible to suppress adverse conditions such as the formation of wrinkles on the non-permeable substrate, the sliding of the non-permeable substrate, and the adhesion of the non-permeable substrate to the conveying member. However, in a conveying member having a concavo-convex surface on the surface, the convex portion contacts the non-permeable substrate, whereas the concave portion does not contact the non-permeable substrate. Therefore, a temperature difference sometimes occurs between a portion where the non-permeable substrate contacts the conveying member and a portion where the non-permeable substrate does not contact the conveying member. This temperature difference sometimes affects the ink film formed on the non-permeable substrate. In particular, in the case of using an aqueous ink containing water, the drying state of the ink film may become uneven by generating a temperature difference in the ink film. The uneven drying state of the ink film is the main cause of uneven image density (also simply referred to as "unevenness").

[0077] The present inventors focused on the amount of ink applied per unit area of the non-permeable substrate, the thickness of the non-permeable substrate, and the width of the smaller one of the concave and convex portions of the conveying member, and found that if these parameters satisfy formula (1), unevenness of the image can be suppressed without impairing the transportability of the conveying member having a concavo-convex surface.

[0078] Japanese Unexamined Patent Application Publication No. 2010-208207 describes a process of conveying a substrate and applying ink using a conveying member having a concavo-convex surface, but there is no description focusing on the above parameters.

[0079] <First Specific Example of Image Recording Apparatus>

[0080] Hereinafter, a first specific example of an image recording apparatus used in the image recording method of the present invention will be described with reference to the accompanying drawings.

[0081] In the drawings and the description thereof in the present invention, for substantially the same elements (for example, components or parts), the same reference numerals are sometimes used and repeated descriptions are omitted.

[0082] Figure 1 It is a diagram conceptually showing a first specific example of an image recording apparatus used in the image recording method of the present invention.

[0083] As Figure 1 shown, an image recording apparatus 100 as a first specific example of an image recording apparatus includes conveying rollers 11 to 16, T1, and T2 of a conveying member for conveying a non-permeable substrate 10.

[0084] The image recording apparatus 100 includes, in order from the upstream side in the conveyance direction of the non-permeable substrate 10 along the conveyance direction: a pretreatment liquid application device 21 for applying a pretreatment liquid onto the non-permeable substrate 10; a pretreatment liquid drying device 31 for drying the pretreatment liquid applied onto the non-permeable substrate 10; an inkjet head 22 for applying ink onto the non-permeable substrate 10 by an inkjet method; and ink drying devices 32 and 33 for drying the ink applied onto the non-permeable substrate 10 to obtain an ink film. In addition, the pretreatment liquid mentioned here corresponds to the first ink described later, and the ink corresponds to the second ink described later. Preferred embodiments of the pretreatment liquid (i.e., the first ink) and the ink (i.e., the second ink) will be described later.

[0085] In the image recording apparatus 100, the non-permeable substrate 10 is conveyed by conveyance rollers 11 to 16, T1, and T2 along Figure 1 the arrow direction in

[0086] The conveyance of the non-permeable substrate 10 is successively subjected to application of the pretreatment liquid by the pretreatment liquid application device 21, drying of the pretreatment liquid by the pretreatment liquid drying device 31, application of the ink by the inkjet head 22, and drying of the ink by the ink drying devices 32 and 33.

[0087] In the present invention, successively performing means that, with respect to a certain point X on the conveyed non-permeable substrate, application of the pretreatment liquid, drying of the pretreatment liquid, application of the ink, and drying of the ink are successively performed.

[0088] The conveyance rollers 11 to 16, which are conveyance members for conveying the non-permeable substrate 10, convey the non-permeable substrate 10 while being in contact with either the application surface (hereinafter, also simply referred to as the "application surface") of the pretreatment liquid and the ink in the non-permeable substrate 10 or the non-application surface (hereinafter, also simply referred to as the "non-application surface") of the pretreatment liquid and the ink.

[0089] Moreover, the conveyance rollers T1 and T2, which are conveyance members for conveying the non-permeable substrate 10, are conveyance rollers having a concavo-convex shape on the surface, and convey the non-permeable substrate 10 while being in contact with the non-application surface of the non-permeable substrate 10. Specifically, the surfaces of the conveyance rollers T1 and T2 are concavo-convex shapes, and the convex portions convey the non-permeable substrate 10 while being in contact with the non-application surface of the non-permeable substrate 10.

[0090] In the image recording apparatus 100 according to the first specific example, first, the non-permeable substrate 10 is conveyed by the conveyance roller 11, and then, the pretreatment liquid is applied onto the non-permeable substrate 10 by the pretreatment liquid application device 21. The pretreatment liquid on the non-permeable substrate 10 is dried by the pretreatment liquid drying device 31, thereby forming a pretreatment liquid film on the non-permeable substrate 10.

[0091] The non-permeable substrate 10 with a pre-treatment liquid film formed thereon is conveyed by the conveying roller 12 in contact with the non-imparting surface, and then, by the conveying roller 13 in contact with the imparting surface, it is conveyed in a configuration where the conveying roller 13 is in contact with the pre-treatment liquid film.

[0092] The non-permeable substrate 10 with a pre-treatment liquid film formed thereon is conveyed by the conveying roller T1 to below the inkjet head 22.

[0093] Ink is imparted from the inkjet head 22 onto the pre-treatment liquid film formed on the non-permeable substrate 10 that has reached below the inkjet head 22.

[0094] The ink imparted onto the pre-treatment liquid film formed on the non-permeable substrate 10 is dried by the ink drying device 32. Drying by the ink drying device 32 is performed under drying conditions weaker than those of the ink drying device 33, thereby forming an ink film on the pre-treatment liquid film.

[0095] The non-permeable substrate 10 with an ink film formed thereon is conveyed by the conveying roller T2 disposed on the downstream side of the ink drying device 32, and then, by the conveying roller 14 in contact with the imparting surface, it is conveyed in a configuration where the conveying roller 14 is in contact with the ink film.

[0096] Furthermore, the non-permeable substrate 10 with an ink film formed thereon is conveyed by the conveying roller 15 in contact with the non-imparting surface, the ink film is dried by the ink drying device 33, and is conveyed by the conveying roller 16 in contact with the non-imparting surface.

[0097] In the image recording apparatus 100, the conveying roller T1, which is a conveying member having an uneven shape on its surface, is disposed on the downstream side of the pre-treatment liquid imparting device 21, and the non-permeable substrate 10 imparted with the pre-treatment liquid can be conveyed by the conveying roller T1. In the image recording apparatus used in the image recording method of the present invention, it is sufficient that the conveying roller having an uneven shape on its surface is disposed on the downstream side of the imparting position of the ink (in the image recording apparatus 100, the pre-treatment liquid) initially imparted onto the non-permeable substrate, and the arrangement positions of the other conveying rollers are not particularly limited.

[0098] In the first specific example, a plurality of inkjet heads may be arranged along the conveying direction at the position of the inkjet head 22. At this time, inks of multiple colors (for example, the first ink and the second ink described later) can be imparted in an overlapping manner.

[0099] At this time, the inks of multiple colors imparted in an overlapping manner can be dried by the ink drying devices 32 and 33, and thus an ink film derived from the inks of multiple colors can be obtained.

[0100] <Second Specific Example of Image Recording Apparatus>

[0101] Hereinafter, a second specific example of an image recording apparatus used in the image recording method of the present invention will be described with reference to the accompanying drawings.

[0102] Figure 2 It is a diagram conceptually showing a second specific example of an image recording apparatus used in the image recording method of the present invention.

[0103] As Figure 2 shown, an image recording apparatus 200 as a first specific example of an image recording apparatus includes conveying rollers 51 and 52 as conveying members for conveying a non-permeable substrate 80, and hot plates T3 and T4 with heaters as a conveying member and a drying device.

[0104] The image recording apparatus 200 sequentially includes, in the conveying direction of the non-permeable substrate 80 from the upstream side in the conveying direction: a pretreatment liquid applying device 61 for applying a pretreatment liquid onto the non-permeable substrate 80; a hot plate T3 with a heater for drying the pretreatment liquid applied onto the non-permeable substrate 80; an inkjet head 62 for applying ink onto the non-permeable substrate 80 by an inkjet method; and a hot plate T4 with a heater for drying the ink applied onto the non-permeable substrate 80 to obtain an ink film.

[0105] In the image recording apparatus 200, the non-permeable substrate 80 is conveyed along Figure 2 the conveying path in which the conveying rollers 51 and 52 and the hot plates T3 and T4 with heaters are arranged in the direction of the arrow.

[0106] The conveyed non-permeable substrate 80 is sequentially subjected to the application of the pretreatment liquid by the pretreatment liquid applying device 61, the drying of the pretreatment liquid by the hot plate T3 with a heater, the application of the ink by the inkjet head 62, and the drying of the ink by the hot plate T4 with a heater.

[0107] The conveying rollers 51 and 52 as conveying members for conveying the non-permeable substrate 80 convey the non-permeable substrate 80 while being in contact with the non-application surface of the non-permeable substrate 80.

[0108] Moreover, the hot plates T3 and T4 with heaters as conveying members for conveying the non-permeable substrate 80 convey the non-permeable substrate 80 while being in contact with the non-application surface of the non-permeable substrate 80. Specifically, the hot plates T3 and T4 with heaters are formed with through holes on the flat surface, and the flat surface conveys the non-permeable substrate 80 while being in contact with the non-application surface of the non-permeable substrate 80.

[0109] In the image recording apparatus 200 according to the second specific example, first, the non-permeable substrate 80 is conveyed by the conveying roller 51, and then, the pretreatment liquid is applied to the non-permeable substrate 80 by the pretreatment liquid applying device 61. The pretreatment liquid on the non-permeable substrate 80 is dried by the platen T3 with a heater, and a pretreatment liquid film is formed on the non-permeable substrate 80.

[0110] The non-permeable substrate 80 formed with the pretreatment liquid film is conveyed by the platen T3 with a heater to below the inkjet head 62.

[0111] Ink is applied from the inkjet head 62 onto the pretreatment liquid film formed on the non-permeable substrate 80 that has reached below the inkjet head 62.

[0112] The ink applied onto the pretreatment liquid film formed on the non-permeable substrate 80 is dried by the platen T4 with a heater.

[0113] Moreover, the non-permeable substrate 80 formed with the ink film is conveyed by the conveying roller 52 that contacts the non-application surface.

[0114] In the image recording apparatus 200, the platen T3 with a heater, which is a conveying member having a concavo-convex shape on its surface, is disposed on the downstream side of the pretreatment liquid applying device 61, and the non-permeable substrate 80 applied with the pretreatment liquid can be conveyed by the platen T3 with a heater. Further, the platen T3 with a heater has a function as a drying device and can dry the pretreatment liquid.

[0115] In the image recording apparatus used in the image recording method of the present invention, the conveying member having a concavo-convex shape on its surface only needs to be disposed on the downstream side of the position where the ink (in the image recording apparatuses 100 and 200, the pretreatment liquid) is initially applied onto the non-permeable substrate, and the arrangement positions of the other conveying members are not particularly limited.

[0116] In the first specific example, a plurality of inkjet heads may be arranged along the conveying direction at the position of the inkjet head 22. In the second specific example, a plurality of inkjet heads may be arranged along the conveying direction at the position of the inkjet head 62. At this time, inks of a plurality of colors (for example, the first ink and the second ink described later) can be applied in an overlapping manner.

[0117] At this time, the inks of a plurality of colors applied in an overlapping manner can be dried by the ink drying devices 32 and 33, and thus an ink film derived from the inks of a plurality of colors can be obtained.

[0118] In the image recording method of the present invention, the pretreatment liquid applying step and the pretreatment liquid drying step may be steps provided as needed.

[0119] Therefore, in the first specific example, without performing the pretreatment liquid application step and the pretreatment liquid drying step, the ink can be directly applied to the non-permeable substrate 10 by the inkjet head 22 without processing by the pretreatment liquid application device 21 and the pretreatment liquid drying device 31.

[0120] That is, the non-permeable substrate 10 can be conveyed so as not to pass through the pretreatment liquid application device 21 and the pretreatment liquid drying device 31.

[0121] In the image recording apparatus 100, a conveying roller having an uneven shape on its surface, that is, the conveying roller T2, is disposed on the downstream side of the inkjet head 22, and the non-permeable substrate 10 to which the ink has been applied can be conveyed by the conveying roller T2.

[0122] In addition, in the first specific example, without performing the pretreatment liquid application step and the pretreatment liquid drying step, the pretreatment liquid application device 21, the pretreatment liquid drying device 31, the conveying rollers 11 to 13, and T1 can also be omitted.

[0123] Moreover, in the second specific example, without performing the pretreatment liquid application step and the pretreatment liquid drying step, the ink can be directly applied to the non-permeable substrate 80 by the inkjet head 62 without processing by the pretreatment liquid application device 61 and the heater-equipped platen T3.

[0124] That is, the non-permeable substrate 80 can be conveyed so as not to pass through the pretreatment liquid application device 61 and the heater-equipped platen T3.

[0125] In the image recording apparatus 200, a heater-equipped platen T4, which is a conveying member having an uneven shape on its surface, is disposed on the downstream side of the inkjet head 62, and the non-permeable substrate 80 to which the ink has been applied can be conveyed by the heater-equipped platen T4.

[0126] The first specific example and the second specific example may include other elements in addition to the above-mentioned elements.

[0127] As other elements, for example, there may be mentioned an unwinding device provided on the most upstream side and used for unwinding a non-permeable substrate wound in a roll shape; a winding device provided on the most downstream side and used for winding the non-permeable substrate provided with an ink film (i.e., an image); a tension applying device for applying tension to the conveyed non-permeable substrate, etc.

[0128] In addition, in the first specific example, the inkjet head is provided only at one location, but an inkjet head and an ink drying device may be further provided on the downstream side of the ink drying device 33. Similarly, in the second specific example, an inkjet head and a heater-equipped platen may be further provided on the downstream side of the heater-equipped platen T4.

[0129] Hereinafter, the image recording method of the present invention will be described in more detail.

[0130] <Conveying member>

[0131] The conveying member used in the image recording method of the present invention is a conveying member having an uneven shape on its surface.

[0132] The form having an uneven shape on the surface may be a form in which protrusions are formed on a flat surface, or a form in which depressions or through-holes are formed on a flat surface.

[0133] In the uneven shape on the surface, the relatively protruding part is called a convex part, and the relatively recessed part is called a concave part.

[0134] For example, when protrusions are formed on a flat surface, the protrusions correspond to the convex parts, and the flat surface corresponds to the concave parts. Also, when depressions or through-holes are formed on a flat surface, the flat surface corresponds to the convex parts, and the depressions or through-holes correspond to the concave parts.

[0135] In the present invention, whether there is a through-hole in the concave part is irrelevant.

[0136] The shapes of the convex part and the concave part are not particularly limited. In the cross-section obtained by cutting in the thickness direction, the cross-sectional view shape may be rectangular, trapezoidal, triangular, semi-circular, or irregular.

[0137] The material of the conveying member is not particularly limited. For example, metals and rubbers can be cited. Surface treatment such as plating can be performed on the surface of the conveying member.

[0138] The shape of the conveying member is not particularly limited and may be cylindrical or flat.

[0139] As the conveying member having an uneven shape on the surface, for example, a suction roller, a grooved roller, a conveyor belt, and a pressure plate can be cited.

[0140] In addition, a heating mechanism may be provided on the conveying member. At this time, heating can be performed while conveying the non-permeable substrate.

[0141] Figures 3A - 3C It is a diagram showing an example of the conveying member used in the image recording method of the present invention.

[0142] Figure 3A The shown conveying member has a plurality of through-holes formed on its surface. Figure 3B The shown conveying member has grooves formed in a direction parallel to the conveying direction of the non-permeable substrate. Figure 3C The shown conveying member has spiral grooves formed symmetrically from the center of the conveying member toward both ends.

[0143] When the larger surface area of the concave part and the convex part is set as T A and the smaller surface area is set as T B , the conveying member preferably satisfies the following formula (6).

[0144] 0.08 ≤ T B / T A ≤ 0.6…(6)

[0145] Compare the surface area of the concave part and the convex part. When the surface area of the concave part is larger, set the surface area of the concave part as T A and set the surface area of the convex part as T B .

[0146] Compare the surface area of the concave part and the convex part. When the surface area of the convex part is larger, set the surface area of the convex part as T A and set the surface area of the concave part as T B .

[0147] If T B / T A is greater than 0.08, wrinkling on the non - permeable substrate can be suppressed and the conveyability is excellent. If T B / T A is less than 0.6, unevenness of the image can be further suppressed.

[0148] The surface areas of the concave part and the convex part in the conveying member are measured by the following method. In addition, when the concave part is a through - hole, the surface area of the concave part refers to the area of the penetrated region.

[0149] Moreover, when there are a plurality of convex parts on the surface of the conveying member, the surface area of the convex part in the conveying member refers to the total surface area obtained by adding up the surface areas of all the convex parts.

[0150] First, calculate the surface area of one of the convex part and the concave part in the conveying member. For example, in the case of a conveying member having a plurality of circular through - holes of the same size formed with respect to a flat surface, the surface area of the concave part can be calculated based on the radius of the through - hole and the number of through - holes.

[0151] And, for example, in the case of a conveying member having a plurality of protrusions of the same size formed with respect to a flat surface, the surface area of the convex part can be calculated based on the shape of the protrusion and the number of protrusions.

[0152] When calculating the surface area of the concave part, the surface area of the convex part can be calculated by subtracting the surface area of the concave part from the surface area of the entire conveying member.

[0153] On the other hand, in the case of calculating the surface area of the convex portion, the surface area of the concave portion can be calculated by subtracting the surface area of the convex portion from the surface area of the entire conveying member.

[0154] Specifically, in the case where a plurality of protrusions of the same size are formed on a flat surface, reference is made to Figures 4A - 4G to describe the calculation method of the surface areas of the concave and convex portions according to the shape of the protrusion.

[0155] As Figure 4A shown, the protrusion of the conveying member 91 is rectangular in cross-section. As Figure 4B shown, the protrusion of the conveying member 92 is rectangular in cross-section, and chamfers are provided at the corners.

[0156] At this time, the surface area of the convex portion is set as the area of the flat portion on the surface of the protrusion.

[0157] In Figure 4A , in the case where the protrusion extends in the direction perpendicular to the paper surface, the surface area of the convex portion is represented by the product of the width a1, the length of the protrusion extending in the direction perpendicular to the paper surface, and the number of protrusions.

[0158] In Figure 4B , in the case where the protrusion extends in the direction perpendicular to the paper surface, the surface area of the convex portion is represented by the product of the width a2, the length of the protrusion extending in the direction perpendicular to the paper surface, and the number of protrusions.

[0159] As Figure 4C shown, the protrusion of the conveying member 93 is trapezoidal in cross-section. As Figure 4D shown, the protrusion of the conveying member 94 is substantially trapezoidal in cross-section.

[0160] At this time, the surface area of the convex portion is set as the area of the flat portion on the surface of the protrusion.

[0161] In Figure 4C , in the case where the protrusion extends in the direction perpendicular to the paper surface, the surface area of the convex portion is represented by the product of the width a3, the length of the protrusion extending in the direction perpendicular to the paper surface, and the number of protrusions.

[0162] In Figure 4D , in the case where the protrusion extends in the direction perpendicular to the paper surface, the surface area of the convex portion is represented by the product of the width a4, the length of the protrusion extending in the direction perpendicular to the paper surface, and the number of protrusions.

[0163] As Figure 4E shown, the protrusion of the conveying member 95 is triangular in cross-section. As Figure 4F shown, the protrusion of the conveying member 96 is substantially triangular in cross-section.

[0164] Thus, in the case where the surface of the protrusion is uneven and the ridge line from the vertex to the bottom of the protrusion is a straight line, the width of the bottom of the protrusion is defined as A5, and the width a5 of the surface of the protrusion is defined as 1 / 10 of A5. Further, in the case where the surface of the protrusion is uneven and the ridge line from the vertex to the bottom of the protrusion is a downward convex curve, the width of the bottom of the protrusion is defined as A6, and the width a6 of the surface of the protrusion is defined as 1 / 10 of A6.

[0165] In Figure 4E when the protrusion is formed by extending in the direction perpendicular to the paper surface, the surface area of the convex portion is represented by the product of the width a5, the length of the protrusion extending in the direction perpendicular to the paper surface, and the number of protrusions.

[0166] In Figure 4F when the protrusion is formed by extending in the direction perpendicular to the paper surface, the surface area of the convex portion is represented by the product of the width a6, the length of the protrusion extending in the direction perpendicular to the paper surface, and the number of protrusions.

[0167] As Figure 4G shown, the protrusion of the conveying member 97 has a semicircular shape in cross-section.

[0168] Thus, in the case where the surface of the protrusion is uneven and the ridge line from the vertex to the bottom of the protrusion is an upward convex curve, the width of the bottom of the protrusion is defined as A7, and the width a7 of the surface of the protrusion is defined as 1 / 3 of A7.

[0169] In Figure 4G when the protrusion is formed by extending in the direction perpendicular to the paper surface, the surface area of the convex portion is represented by the product of the width a7, the length of the protrusion extending in the direction perpendicular to the paper surface, and the number of protrusions.

[0170] <Equations (1), (2), (3)>

[0171] In the present invention, when the amount of ink applied per unit area of the non-permeable substrate is V (g / m 2 ²), the thickness of the non-permeable substrate is t (μm), and the width of the smaller one of the concave and convex portions of the conveying member is A (μm), V, t, and A satisfy the following equation (1).

[0172] 10 ≤ (V / t) × A ≤ 4000…(1)

[0173] If "(V / t) × A" is 10 or more, it is possible to suppress defects such as the formation of wrinkles on the non-permeable substrate, the sliding of the non-permeable substrate, and the adhesion of the non-permeable substrate to the conveying member, and thus the transportability is excellent. On the other hand, if "(V / t) × A" is 4000 or less, it is possible to suppress the temperature difference in the ink film, and thus the image unevenness is suppressed.

[0174] From the viewpoint of maintaining transportability and suppressing unevenness of the image, it is preferable that V, t, and A satisfy the following formula (2).

[0175] 10 ≤ (V / t) × A ≤ 2000…(2)

[0176] From the viewpoint of maintaining transportability and further suppressing unevenness of the image, it is preferable that V, t, and A satisfy the following formula (3).

[0177] 10 ≤ (V / t) × A ≤ 1000…(3)

[0178] Moreover, it is preferable that "(V / t) × A" be 15 or more. If "(V / t) × A" is 15 or more, it is possible to suppress adverse conditions such as formation of wrinkles on the non-permeable substrate, sliding of the non-permeable substrate, and adhesion of the non-permeable substrate to the transport member, and thus the transportability is more excellent.

[0179] 〔V〕

[0180] In the case of applying ink by an inkjet recording apparatus, the amount of ink applied per unit area of the non-permeable substrate can be adjusted by the ejection amount, resolution, drawing pattern, etc.

[0181] The amount of ink applied per unit area of the non-permeable substrate is not particularly limited as long as it satisfies formula (1), and is preferably 1 g / m 2 ~25 g / m 2 and more preferably 2 g / m 2 ~20 g / m 2 .

[0182] If the above-mentioned application amount is 1 g / m 2 or more, water is difficult to evaporate and the transportability is improved.

[0183] On the other hand, if the above-mentioned application amount is 25 g / m 2 or less, the ink is difficult to flow and unevenness of the image is suppressed.

[0184] In the case where the ink is an ink containing water and a flocculant, the above-mentioned application amount is preferably 1 g / m 2 ~10 g / m 2 and more preferably 1 g / m 2 ~5 g / m 2 .

[0185] Moreover, in the case where the ink is an ink containing water and a pigment, the above-mentioned application amount is preferably 1 g / m 2 ~25 g / m 2 and more preferably 2 g / m 2 ~20 g / m 2 .

[0186] 〔t〕

[0187] The thickness of the non-permeable substrate is measured by the following method.

[0188] Measure the thickness at 10 randomly selected positions in the non-permeable substrate using a film thickness gauge. Calculate the arithmetic mean of the measured values and adopt the obtained value.

[0189] The thickness of the non-permeable substrate is not particularly limited as long as it satisfies formula (1), preferably 0.1 μm to 1,000 μm, more preferably 0.1 μm to 800 μm, still more preferably 1 μm to 500 μm, and particularly preferably 10 μm to 100 μm.

[0190] If the thickness of the non-permeable substrate is 0.1 μm or more, it is difficult to transfer heat from the conveying member, thereby suppressing unevenness of the image.

[0191] On the other hand, if the thickness of the non-permeable substrate is 1,000 μm or less, it follows the surface of the conveying member and has excellent transportability.

[0192] 〔A〕

[0193] When measuring the width of the one with a smaller surface area among the concave and convex portions of the conveying member, calculate the surface areas of the concave and convex portions of the conveying member.

[0194] Next, compare the calculated surface area of the concave portion with the surface area of the convex portion to determine the one with the smaller surface area. In the case where the calculated surface areas of the concave portion and the convex portion are the same, adopt the width of the convex portion.

[0195] Compare the surface area of the concave portion with the surface area of the convex portion. When the surface area of the concave portion is smaller, set the width of the concave portion as A.

[0196] Compare the surface area of the concave portion with the surface area of the convex portion. When the surface area of the convex portion is smaller, set the width of the convex portion as A.

[0197] In the present invention, the width of the convex or concave portion means the maximum value among the lengths in the direction perpendicular to and parallel to the conveying direction of the non-permeable substrate. In the case where there are a plurality of concave portions in the conveying member, adopt the average value of the widths of the respective concave portions. Similarly, in the case where there are a plurality of convex portions in the conveying member, adopt the average value of the widths of the respective convex portions.

[0198] As Figure 3A shown in the conveying member, in the case where the concave portions are arranged discontinuously, if the shape of the concave portion is circular, the width of the concave portion means the diameter of the circle.

[0199] As Figure 3BIn the case where grooves are formed in a direction parallel to the conveyance direction of the non-permeable substrate as in the conveyance member shown, the width of the convex portion or the concave portion becomes the maximum value of the length in the direction perpendicular to the conveyance direction of the non-permeable substrate. On the other hand, in the case where grooves are formed in a direction perpendicular to the conveyance direction of the non-permeable substrate, the width of the convex portion or the concave portion becomes the maximum value of the length in the direction parallel to the conveyance direction of the non-permeable substrate.

[0200] As Figure 3C in the case of the conveyance member shown, when spiral grooves are symmetrically formed from the center of the conveyance member toward both end portions in the left-right direction, the lengths in the direction perpendicular to the conveyance direction of the non-permeable substrate and in the parallel direction are measured respectively, and the maximum value is adopted as the width.

[0201] Further, for example, in the case of a conveyance member having a plurality of projections of the same size formed on a flat surface, as described above, the width of the convex portion is Figures 4A - 4G a1 to a7 as shown. The width of the concave portion is the width between adjacent convex portions, and as Figures 4A - 4G shown, is b1 to b7.

[0202] In addition, when there are a plurality of concave portions or convex portions in the conveyance member and the widths of the concave portions or convex portions are not constant, the average value of the measured values of the respective widths is adopted.

[0203] The width of the one with a smaller surface area among the concave portion and the convex portion of the conveyance member is not particularly limited as long as it satisfies Expression (1), and is preferably 10 μm to 10,000 μm, more preferably 20 μm to 5,000 μm.

[0204] If the above width is 10 μm or more, the sliding of the non-permeable substrate is suppressed and the conveyance property is excellent.

[0205] On the other hand, if the above width is 10,000 μm or less, unevenness of the image can be suppressed.

[0206] <Expression (4)>

[0207] In the present invention, when the surface free energy of the non-permeable substrate is set to E1 (mN / m), the surface tension of the ink is set to E2 (mN / m), and the value obtained by subtracting E2 from E1 is set to ΔE, it is preferably to satisfy the following Expression (4).

[0208] △E / E2 ≤ 0.50…(4)

[0209] If ΔE / E2 is 0.50 or less, the ink hardly flows and unevenness of the image is suppressed. From the viewpoint of further suppressing unevenness of the image, ΔE / E2 is more preferably 0.35 or less. The lower limit value of ΔE / E2 is not particularly limited and is, for example, 0.

[0210] The smaller the ΔE, the more difficult it is for the ink to flow, and the more the non-uniformity of the image is suppressed. Therefore, ΔE is preferably 20 mN / m or less, more preferably 15 mN / m or less. The lower limit value of ΔE is not particularly limited, for example, it is 0 mN / m.

[0211] The preferred range of the surface tension of the ink will be described later.

[0212] From the viewpoint of the affinity with the ink, the surface free energy of the non-permeable substrate is preferably 30 mN / m to 70 mN / m, more preferably 30 mN / m to 60 mN / m.

[0213] In the present invention, the surface free energy is calculated by the Owens-Wendt method.

[0214] Using the measured values of the contact angles of water and diiodomethane with respect to the surface of the non-permeable substrate, the dispersion components and polar components of water and diiodomethane, and by the Owens-Wendt method, the surface free energy of the non-permeable substrate is calculated.

[0215] Using a contact angle meter, the contact angles of water and diiodomethane with the surface of the non-permeable substrate are measured. As the contact angle meter, for example, a product named "DM-501" manufactured by Kyowa Interface Science Co., Ltd. can be used.

[0216] The Owens-Wendt method is described in D.K. Owens, and R.C. Wendt, Journal of applied polymer science Vol.13, PP.1741 - 1747, (1969).

[0217] Hereinafter, a specific calculation method will be described. When a liquid is dropped onto a solid surface (here, a non-permeable substrate), the following equation holds for each parameter at the interface between the solid surface and the liquid.

[0218] The following formula 1 is well-known as Young's equation.

[0219] The following formula 2 is well-known as Dupre's equation.

[0220] The following formulas 3, 4 and 5 are well-known as equations based on the Owens-Wendt method.

[0221] γ S =γ L cosθ + γ SL …(1)

[0222] W=γS +γ L -γ SL …(2)

[0223] γ S =γ S d +γ S h …(3)

[0224] γ L =γ L d +γ L h …(4)

[0225] W = 2(γ S d γ L d ) 1 / 2 + 2(γ S h γ L h ) 1 / 2 …(5)

[0226] In Formulas 1 to 5, the detailed content of each symbol is as follows.

[0227] θ... Contact angle of the liquid with the surface of the non - permeable substrate

[0228] γ S … Surface free energy of the non - permeable substrate

[0229] γ L … Surface free energy of the liquid

[0230] γ SL … Interfacial free energy between the non - permeable substrate and the liquid

[0231] W... Adhesion work

[0232] γ S d … Dispersive component of the surface free energy of the non - permeable substrate

[0233] γ S h … Polar component of the surface free energy of the non - permeable substrate

[0234] γ L d … Dispersive component of the surface free energy of the liquid

[0235] γ L h … Polar component of the surface free energy of the liquid

[0236] By using the above formulas (1) to (5), the following formula (6) is obtained.

[0237] (γ S d γ L d ) 1 / 2 +(γ S h γ L h ) 1 / 2 =γ L (1 + cosθ) / 2…(6)

[0238] As the liquid in formula (6), water and diiodomethane are used, and they are set as formula (6A) and formula (6B).

[0239] (γ S d γ L1 d ) 1 / 2 +(γ S h γ L1 h ) 1 / 2 =γ L1 (1 + cosθ1) / 2…(6A)

[0240] (γ S d γ L2 d ) 1 / 2 +(γ S h γ L2 h ) 1 / 2 =γ L2 (1 + cosθ2) / 2…(6B)

[0241] In formulas (6A) and (6B), the detailed content of each symbol is as follows.

[0242] θ1…Contact angle between water and the surface of the non - permeable substrate

[0243] θ2 - Contact angle between the non - permeable substrate and the surface of diiodomethane

[0244] γ L1 …Surface free energy of water (72.8 mN / m)

[0245] γ L1 d …Dispersive component of the surface free energy of water (21.8 mN / m)

[0246] γ L1 h…Polar component of the surface free energy of water (51.0 mN / m)

[0247] γ L2 …Surface free energy of diiodomethane (50.8 mN / m)

[0248] γ L2 d …Dispersion component of the surface free energy of diiodomethane (50.8 mN / m)

[0249] γ L2 h …Polar component of the surface free energy of diiodomethane (0 mN / m)

[0250] In addition, the values in parentheses are the values described in the literature.

[0251] By substituting θ1, θ2, γ L1 , γ L1 d , γ L1 h , γ L2 , γ L2 d and γ L2 h into Equation 6A and Equation 6B, γ S d and γ S h are calculated.

[0252] As θ1 and θ2, the measured values based on the above measurement method are used.

[0253] By substituting the calculated γ S d and γ S h into Equation 3, the surface free energy γ S of the non-permeable substrate is calculated.

[0254] <Equation (5)>

[0255] In the present invention, when the surface free energy of the non-permeable substrate is set to E1 (mN / m), the surface tension of the ink is set to E2 (mN / m), and the value obtained by subtracting E2 from E1 is set to ΔE, it is preferable to satisfy the following Equation (5).

[0256] 4 ≤ (V / t) × A × (ΔE / E2) ≤ 1200…(5)

[0257] If "(V / t) × A × (ΔE / E2)" is 4 or more, the transportability is improved. On the other hand, if "(V / t) × A × (ΔE / E2)" is 1200 or less, unevenness of the image can be further suppressed.

[0258] From the above viewpoints, “(V / t)×A×(△E / E2)” is more preferably from 6 to 450.

[0259] <Ink application step>

[0260] The image recording method of the present invention includes a step of applying an ink containing water onto a non-permeable substrate.

[0261] (Non-permeable substrate)

[0262] In the present invention, the non-permeability of the non-permeable substrate means a property that the water absorption rate at 24 hours measured in accordance with ASTM D570-98(2018) is 2.5% or less. Here, “%” as the unit of the water absorption rate is based on mass. The above water absorption rate is preferably 1.0% or less, and more preferably 0.5% or less.

[0263] As the material of the non-permeable substrate, for example, glass, metals (such as aluminum, zinc, copper, etc.), and resins (such as 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.) can be mentioned.

[0264] The material of the non-permeable substrate is preferably a resin. That is, the non-permeable substrate is preferably a resin substrate.

[0265] Among them, from the viewpoint of versatility, the material of the non-permeable substrate is preferably polypropylene, polyethylene, polyethylene terephthalate, nylon, acrylic resin, or polyvinyl chloride.

[0266] The shape of the non-permeable substrate is preferably sheet-like (film-like) or plate-like. As the non-permeable substrate having such a shape, a glass plate, a metal plate, a resin sheet (resin film), paper laminated with plastic, paper laminated or vapor-deposited with metal, and a plastic sheet (plastic film) laminated or vapor-deposited with metal can be mentioned.

[0267] As the resin-made non-permeable substrate, a resin sheet (resin film) can be mentioned. Specifically, a flexible packaging material for packaging foods, etc., and a floor guide board in a large retail store can be mentioned.

[0268] As the non-permeable substrate, in addition to the sheet-like (film-like) or plate-like non-permeable substrate, textiles (fabrics) and non-woven fabrics formed of non-permeable fibers can also be mentioned.

[0269] For non-permeable substrates, a hydrophilic treatment can be carried out. Examples of the hydrophilic treatment include corona treatment, plasma treatment, flame treatment, heat treatment, abrasion treatment, and light irradiation treatment (such as UV treatment), but are not limited thereto. For example, corona treatment can be performed using a corona master (product name "PS-10S", manufactured by Shinko Electric & Instrumentation Co., Ltd.). The conditions for corona treatment can be appropriately selected according to the type of non-permeable substrate, etc.

[0270] The non-permeable substrate can be a non-permeable substrate having transparency.

[0271] Here, having transparency means that the transmittance of visible light with a wavelength of 400 nm to 700 nm is 80% or more (preferably 90% or more).

[0272] When the non-permeable substrate is a non-permeable substrate having transparency, it is easy to visually recognize an image through the non-permeable substrate from the image non-recording surface side of the non-permeable substrate.

[0273] For example, when the non-permeable substrate is a non-permeable substrate having transparency, and a pretreatment liquid, a coloring ink described later, and a white ink described later are sequentially applied on the non-permeable substrate to record an image, it is easy to visually recognize a colored image (such as a pattern image of characters, graphics, etc.) with a white image (such as a solid image) as the background through the non-permeable substrate from the image non-recording surface side of the non-permeable substrate.

[0274] (Ink)

[0275] Examples of the water-containing ink include an ink containing water and a flocculant, and an ink containing water and a pigment. Examples of the ink containing water and a pigment include a white ink containing water and a white pigment, and a coloring ink containing water and a coloring pigment. Among them, the ink is preferably a white ink containing water and a white pigment.

[0276] Here, the coloring pigment refers to a colored pigment (such as a cyan pigment, a magenta pigment, a yellow pigment, etc.) or a black pigment (hereinafter, also referred to as a black pigment).

[0277] Furthermore, the coloring ink refers to a colored ink (such as a cyan ink, a magenta ink, a yellow ink, etc.) or a black ink (hereinafter, also referred to as a black ink).

[0278] In the ink application step, only one kind of ink containing water and a pigment can be applied on the non-permeable substrate, or two or more kinds can be applied.

[0279] In the ink application step, a white ink and a coloring ink can be sequentially and overlappedly applied on the non-permeable substrate.

[0280] At this time, the white ink and the colored ink can be applied in sequence, or the colored ink and the white ink can be applied in sequence.

[0281] Moreover, in the ink application step, the following steps may be included: applying a first ink containing water and a flocculant to a non-permeable substrate; and applying a second ink (for example, white ink and colored ink) containing water and a pigment to the non-permeable substrate to which the first ink has been applied. Specifically, after applying the first ink, the white ink and the colored ink as the second ink can be applied in sequence, or after applying the first ink, the colored ink and the white ink as the second ink can be applied in sequence.

[0282] Hereinafter, a preferred embodiment of the ink containing water and a pigment (i.e., the second ink) will be described.

[0283] - Water -

[0284] The second ink contains water.

[0285] The content of water is preferably 10% by mass or more, more preferably 20% by mass or more, still more preferably 30% by mass or more, and particularly preferably 50% by mass or more with respect to the total amount of the ink.

[0286] The upper limit of the content of water with respect to the total amount of the second ink can be appropriately determined according to the content of other components, for example, 99% by mass, preferably 95% by mass, and more preferably 90% by mass.

[0287] - Pigment -

[0288] The second ink contains a pigment.

[0289] When the second ink is a colored ink, it contains a coloring pigment as a pigment.

[0290] When the second ink is a white ink, it contains a white pigment as a pigment.

[0291] The coloring pigment can be any of commonly commercially available organic pigments and inorganic pigments.

[0292] Examples of the coloring pigment include the pigments described in Shojiro Ito (editor), "Encyclopedia of Pigments" (published in 2000), W. Herbst, K. Hunger, "Industrial Organic Pigments", Japanese Patent Laid-Open No. 2002-12607, Japanese Patent Laid-Open No. 2002-188025, Japanese Patent Laid-Open No. 2003-26978, and Japanese Patent Laid-Open No. 2003-342503.

[0293] Moreover, the coloring pigment may be a water-insoluble pigment that can be dispersed in water by a dispersant, or a self-dispersible pigment.

[0294] A self-dispersible pigment is a pigment that can be dispersed in water even without using a dispersant.

[0295] Examples of the self-dispersible pigment include compounds in which at least one selected from the group consisting of hydrophilic groups such as a carbonyl group, a hydroxyl group, a carboxyl group, a sulfo group, and a phosphate group and salts thereof is directly or via another group chemically bonded to the pigment surface.

[0296] From the viewpoints of image density and ink ejection property, the content of the coloring pigment in the second ink when the second ink contains the coloring pigment is preferably 1% by mass to 20% by mass, more preferably 1% by mass to 15% by mass, and further preferably 1% by mass to 10% by mass with respect to the total amount of the second ink.

[0297] Examples of the white pigment include inorganic pigments such as titanium dioxide, barium sulfate, calcium carbonate, silicon dioxide, zinc oxide, zinc sulfide, mica, talc, and pearl.

[0298] The white pigment is preferably titanium dioxide, barium sulfate, calcium carbonate, or zinc oxide, and more preferably titanium dioxide.

[0299] 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. Moreover, from the viewpoint of ink ejection property, the average primary particle diameter of the white pigment is preferably 400 nm or less, more preferably 350 nm or less.

[0300] In the present invention, the average primary particle diameter of the white pigment is a value measured using a transmission electron microscope (TEM). Specifically, it is a value obtained by measuring the primary particle diameters of any 50 white pigments present in the field of view observed by TEM and averaging them. As the transmission electron microscope, a transmission electron microscope 1200EX manufactured by JEOL Ltd. can be used.

[0301] From the viewpoints of image density and ejection property, the content of the white pigment in the second ink when the second ink contains the white pigment is preferably 2% by mass to 25% by mass, more preferably 5% by mass to 25% by mass, and further preferably 10% by mass to 20% by mass with respect to the total amount of the second ink.

[0302] -Resin-

[0303] The second ink preferably contains at least one resin.

[0304] The resin in the second ink contributes to the film-forming property of the ink (i.e., the formation property of the ink film).

[0305] The weight-average molecular weight (Mw) of the resin is preferably from 1,000 to 300,000, more preferably from 2,000 to 200,000, and still more preferably from 5,000 to 100,000.

[0306] In the present invention, unless otherwise specified, the weight-average molecular weight (Mw) refers to the value measured by gel permeation chromatography (GPC).

[0307] In the measurement by gel permeation chromatography (GPC), as the measurement apparatus, HLC (registered trademark)-8020GPC (TOSOH CORPORATION) is used, as the column, three TSKgel (registered trademark) Super Multipore HZ-H (4.6 mm ID × 15 cm, TOSOH CORPORATION) are used, and as the eluent, THF (tetrahydrofuran) is used. Further, as the measurement conditions, the sample concentration is set to 0.45 mass%, the flow rate is set to 0.35 ml / min, the sample injection volume is set to 10 μl, and the measurement temperature is set to 40°C, and the measurement is carried out using an RI detector.

[0308] The calibration curve is prepared using eight samples of "Standard Sample TSK standard, polystyrene" of TOSOH Corporation: "F-40", "F-20", "F-4", "F-1", "A-5000", "A-2500", "A-1000", and "n-propylbenzene".

[0309] Examples of the resin include a pigment dispersion resin as a pigment dispersant.

[0310] Examples of the resin also include resin particles.

[0311] The second ink may contain at least one kind of pigment dispersion resin.

[0312] The pigment dispersion resin is a resin having a function of dispersing pigments.

[0313] The pigment dispersion resin may be a random copolymer or a block copolymer.

[0314] The pigment dispersion resin may have a crosslinked structure.

[0315] The second ink can be prepared using a pigment dispersion liquid containing a pigment and a pigment dispersion resin.

[0316] Regarding the pigment dispersion resin, for example, known polymer dispersants such as the polymer dispersant described in paragraphs 0029 to 0106 of International Publication No. 2021 / 221069 can be used.

[0317] In the case where the second ink contains a pigment-dispersing resin, the ratio of the content of the pigment to the content of the pigment-dispersing resin in the second ink is preferably 1:0.04 to 1:3, more preferably 1:0.05 to 1:1, and still more preferably 1:0.05 to 1:0.5, on a mass basis.

[0318] In the case where the second ink contains a pigment-dispersing resin, the content of the pigment-dispersing resin relative to the total amount of the second ink is preferably 0.1% by mass to 10% by mass, more preferably 0.3% by mass to 5% by mass, and still more preferably 0.5% by mass to 2.5% by mass.

[0319] The second ink may contain at least one kind of resin particle.

[0320] The resin constituting the resin particles is preferably a water-insoluble resin. "Water-insoluble" in the water-insoluble resin means a property that the dissolution amount in 100 g of distilled water at 25°C is less than 2 g.

[0321] The volume average particle diameter of the resin particles is preferably 1 nm to 300 nm, more preferably 3 nm to 200 nm, and still more preferably 5 nm to 150 nm.

[0322] In the present invention, the volume average particle diameter means a value measured by a laser diffraction / scattering particle size distribution analyzer.

[0323] As the measuring device, for example, the particle size distribution measuring device "Microtrac MT-3300II" (manufactured by Nikkiso Co., Ltd.) can be cited.

[0324] As the resin particles, 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 is preferred.

[0325] In the present invention, the acrylic resin means a polymer (homopolymer or copolymer) of a raw material monomer containing at least one selected from the group consisting of acrylic acid, derivatives of acrylic acid (such as acrylate, etc.), methacrylic acid, and derivatives of methacrylic acid (such as methacrylate, etc.).

[0326] 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, more preferably 50°C to 150°C.

[0327] Here, the glass transition temperature (Tg) of the resin particles applies the measured Tg obtained by actual measurement. Regarding the measuring method of the measured Tg, reference can be made to paragraph 0111 of Japanese Unexamined Patent Application Publication No. 2015-25076.

[0328] Regarding the resin particles, for example, paragraphs 0038 to 0114 of International Publication No. 2021 / 192720, paragraphs 0109 to 0120 of Japanese Patent Laid-Open No. 2015-25076, etc. can be referred to.

[0329] When the second ink contains resin particles, the content of the resin particles in the second ink is preferably 1% by mass to 20% by mass, more preferably 2% by mass to 15% by mass, and further preferably 2% by mass to 10% by mass with respect to the total amount of the second ink.

[0330] -Water-soluble organic solvent-

[0331] The second ink preferably contains at least one water-soluble organic solvent.

[0332] Thereby, the ejection stability from the inkjet head can be ensured.

[0333] The water-soluble organic solvent contained in the second ink may be one kind or two or more kinds.

[0334] In the present invention, "water-soluble" in "water-soluble organic solvent" means a property of dissolving 1 g or more in 100 g of water at 25°C.

[0335] The types of water-soluble organic solvents that can be contained in the second ink are not limited. For example, the following can be cited:

[0336] Monohydric alcohols having 1 to 4 carbon atoms;

[0337] Diols such as 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, 4-methyl-1,2-pentanediol;

[0338] Triols such as glycerol, 1,2,6-hexanetriol, trimethylolpropane;

[0339] Alkylene diols such as ethylene glycol and propylene glycol;

[0340] Alkylene glycol monoalkyl ethers such as ethylene glycol monoalkyl ether and propylene glycol monoalkyl ether;

[0341] Polyalkylene diols such as diethylene glycol, triethylene glycol, tetraethylene glycol, pentaethylene glycol, dipropylene glycol, polyoxyethylene polyoxypropylene glycol;

[0342] Polyalkylene glycol ethers such as diethylene glycol monoalkyl ether, triethylene glycol monoalkyl ether, tripropylene glycol monoalkyl ether, polyoxypropylene glycerol ether; and

[0343] 2-Pyrrolidone, N-methyl-2-pyrrolidone;

[0344] etc.

[0345] From the viewpoint of ejection stability, the water-soluble organic solvent in the second ink preferably contains at least one selected from the group consisting of alkylene glycols and alkylene glycol monoalkyl ethers.

[0346] The content of the water-soluble organic solvent is preferably 10% by mass to 40% by mass, more preferably 15% by mass to 30% by mass, relative to the total amount of the second ink.

[0347] - Additives -

[0348] If necessary, the second ink may also contain additives such as surfactants, water-soluble resins, co-sensitizers, ultraviolet absorbers, antioxidants, anti-fading agents, conductive salts, and basic compounds.

[0349] - Physical properties -

[0350] From the viewpoint of improving ejection stability, the pH (25 °C) of the second ink is preferably 7 to 10, more preferably 7.5 to 9.5.

[0351] Regarding the pH of the second ink, it is measured at 25 °C using a pH meter. For example, it is measured using a pH meter (product name "WM-50EG") manufactured by DKK-TOA CORPORATION.

[0352] The viscosity (25 °C) of the second ink is preferably 0.5 mPa·s to 30 mPa·s, more preferably 2 mPa·s to 20 mPa·s, further preferably 2 mPa·s to 15 mPa·s, and particularly preferably 3 mPa·s to 10 mPa·s.

[0353] The viscosity of the second ink is measured at 25 °C using a viscometer. For example, it is measured using a TV-22 type viscometer manufactured by Toki Sangyo Co., Ltd.

[0354] The surface tension of the second ink is preferably 60 mN / m or less, more preferably 20 mN / m to 50 mN / m, and further preferably 25 mN / m to 40 mN / m.

[0355] Regarding the surface tension of the second ink, it is measured at 25 °C using a surface tension meter. For example, it is measured using an automatic surface tension meter (product name "CBVP-Z") manufactured by Kyowa Interface Science Co., Ltd. by the plate method.

[0356] Hereinafter, a preferred embodiment of the ink containing water and a flocculant (i.e., the first ink) will be described.

[0357] - Water -

[0358] The first ink contains water.

[0359] The content of water is preferably 50% by mass or more, more preferably 60% by mass or more, based on the total amount of the first ink.

[0360] The upper limit of the content of water depends on the amount of other components, but is preferably 90% by mass or less, more preferably 80% by mass or less, based on the total amount of the first ink.

[0361] - Flocculant -

[0362] The first ink contains at least one flocculant.

[0363] The flocculant in the first ink causes the components in the ink to flocculate on the non - permeable substrate. Thereby, the image quality can be improved.

[0364] The flocculant is preferably at least one selected from the group consisting of organic acids, polyvalent metal compounds, metal complexes, and cationic polymers.

[0365] As the flocculant, the flocculants described in paragraphs 0122 to 0130 of WO 2020 / 195360 can be preferably cited.

[0366] Hereinafter, preferred embodiments of the organic acid, polyvalent metal compound, metal complex, and cationic polymer that can be used as the flocculant will be described.

[0367] -- Organic acid --

[0368] As the organic acid, an organic compound having an acidic group can be cited.

[0369] As the acidic group, a phosphoric acid group, a phosphonic acid group, a hypophosphorous acid group, a sulfuric acid group, a sulfonic acid group, a sulfinic acid group, and a carboxyl group can be cited.

[0370] Among them, from the viewpoint of the flocculation rate of the ink, the acidic group is preferably a phosphoric acid group or a carboxyl group, more preferably a carboxyl group.

[0371] It is preferred that at least a part of the acidic group dissociates in the first ink.

[0372] Examples of the organic compound having a carboxyl 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.

[0373] Among them, from the viewpoint of the aggregation rate of the ink, the organic compound having a carboxyl group is preferably a carboxylic acid having a valence of 2 or more (hereinafter, also referred to as polycarboxylic acid), and more preferably a dicarboxylic acid.

[0374] 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.

[0375] The organic acid preferably has a low pKa (for example, 1.0 to 5.0). Thus, the surface charge of particles such as pigments and resin particles in the ink dispersed and stabilized by weakly acidic functional groups such as carboxyl groups is reduced by contacting with an organic acid having a lower pKa, thereby reducing the dispersion stability.

[0376] The organic acid preferably has a low pKa, high solubility in water, and a valence of 2 or more. Further, the organic acid more preferably has a high buffering capacity in a pH region lower than the pKa of the functional group (for example, carboxyl group, etc.) that disperses and stabilizes the particles in the ink.

[0377] --Polyvalent metal compound--

[0378] Examples of the polyvalent metal compound include polyvalent metal salts.

[0379] Examples of the polyvalent metal salt include organic acid polyvalent metal salts and inorganic acid polyvalent metal salts.

[0380] As the organic acid polyvalent metal salt, polyvalent metal salts of the above-mentioned organic acids (for example, formic acid, acetic acid, benzoic acid, etc.) are preferred.

[0381] As the inorganic acid polyvalent metal salt, polyvalent metal salts of nitric acid, hydrochloric acid, or thiocyanic acid are preferred.

[0382] Examples of the polyvalent metal salt include salts of alkaline earth metals (for example, magnesium, calcium) in Group 2 of the periodic table, salts of transition metals (for example, lanthanum) in Group 3 of the periodic table, salts of metals in Group 13 of the periodic table (for example, aluminum), and salts of lanthanide elements (for example, neodymium).

[0383] As the polyvalent metal salt, a calcium salt, a magnesium salt or an aluminum salt is preferred, and a calcium salt or a magnesium salt is more preferred.

[0384] As the polyvalent metal compound, an organic acid polyvalent metal salt is preferred, and an organic acid calcium salt or an organic acid magnesium salt is more preferred.

[0385] Preferably, at least a part of the polyvalent metal compound dissociates into polyvalent metal ions and counter ions in the first ink.

[0386] --Metal complex--

[0387] The metal complex preferably contains at least one selected from the group consisting of zirconium, aluminum and titanium as a metal element.

[0388] The metal complex preferably contains a metal complex having at least one selected from the group consisting of acetate, acetylacetonate, methyl acetoacetate, ethyl acetoacetate, octanediol, butoxyacetylacetone, lactate, ammonium lactate and triethanolaminate as a ligand.

[0389] The metal complex may be a commercially available product. Various organic ligands, especially various polydentate ligands capable of forming a metal chelate catalyst, are commercially available. Therefore, the metal complex may be a metal complex prepared by combining a commercially available organic ligand and a metal.

[0390] --Cationic polymer--

[0391] The cationic polymer is preferably a homopolymer of a cationic monomer having a primary to tertiary amino group or a quaternary ammonium salt group, a copolymer or a condensate of a cationic monomer and a non-cationic monomer. As the cationic polymer, it can be used in either a water-soluble polymer or a water-insoluble polymer (i.e., latex particles) form.

[0392] Examples of the cationic polymer include polyvinylpyridinium salts, polyalkylaminoethyl acrylates, polyalkylaminoethyl methacrylates, polyvinylimidazoles, polyethyleneimines, polybiguanides, polyguanides, polyallylamines and their derivatives.

[0393] From the viewpoint of the viscosity of the first ink, the weight-average molecular weight of the cationic polymer is preferably small. When the first ink is applied to a resin substrate by an inkjet recording method, it is preferably 1,000 to 500,000, more preferably 1,500 to 200,000, and still more preferably 2,000 to 100,000. If the weight-average molecular weight is 1,000 or more, it is advantageous from the viewpoint of the aggregation rate. When the weight-average molecular weight is 500,000 or less, it is advantageous from the viewpoint of ejection reliability. However, when the first ink is applied to a resin substrate by a method other than the inkjet recording method, it is not limited thereto.

[0394] The content of the aggregating agent in the first ink is preferably 0.1% by mass to 40% by mass, more preferably 0.1% by mass to 30% by mass, still more preferably 1% by mass to 20% by mass, and particularly preferably 1% by mass to 10% by mass with respect to the total amount of the first ink.

[0395] - Resin -

[0396] The first ink contains at least one resin.

[0397] The resin in the first ink contributes to the film-forming property of the first ink (i.e., the film-forming property of the first ink film).

[0398] As the resin in the first ink, the same resin (for example, resin particles) as the resin in the second ink can be used.

[0399] The content of the resin in the first ink is not particularly limited.

[0400] The content of the resin 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 with respect to the total amount of the first ink.

[0401] - Water-soluble organic solvent -

[0402] The first ink may contain at least one water-soluble organic solvent.

[0403] As the water-soluble organic solvent in the first ink, the same solvent as the water-soluble organic solvent that the ink can contain can be used.

[0404] - Additive -

[0405] The ink may contain additives such as a surfactant, a water-soluble resin, a co-sensitizer, an ultraviolet absorber, an antioxidant, an anti-fading agent, a conductive salt, and a basic compound as needed.

[0406] - Physical properties -

[0407] The pH of the first ink is preferably 2.0 to 7.0, more preferably 2.0 to 4.0. The pH of the first ink is measured by the same method as the pH of the second ink.

[0408] From the viewpoint of the coatability of the first ink, the viscosity of the first ink is preferably 0.5 mPa·s to 10 mPa·s, more preferably 1 mPa·s to 5 mPa·s. The viscosity is the value measured at 25°C using a viscometer. The viscosity of the first ink is measured by the same method as the viscosity of the second ink.

[0409] The surface tension of the first ink is preferably 60 mN / m or less, more preferably 20 mN / m to 50 mN / m, and further preferably 30 mN / m to 45 mN / m. The surface tension is the value measured at a temperature of 25°C. The surface tension of the first ink is measured by the same method as the surface tension of the second ink.

[0410] (Method of applying the ink)

[0411] The method of applying the ink is not particularly limited, and known methods such as a coating method, an impregnation method, and an inkjet recording method can be cited.

[0412] As the coating method, known methods such as using a bar coater, an extrusion die coater, an air knife coater, a blade coater, a rod coater, a knife coater, an extrusion coater, and an inverse roll coater can be cited.

[0413] The application of the first ink is preferably carried out by a coating method.

[0414] The application of the second ink (for example, white ink and colored ink) is preferably carried out by an inkjet method.

[0415] There is no particular limitation on the ink ejection method in the inkjet method, and it can be a known method. For example, a charge control method that ejects ink using an electrostatic induction force, a drop-on-demand inkjet method (pressure pulse method) that uses the vibration pressure of a piezoelectric element, an acoustic inkjet method that converts an electrical signal into a sound beam and irradiates the ink and uses the radiation pressure to eject the ink, and a thermal inkjet (Bubble Jet (registered trademark)) method that heats the ink to form bubbles and uses the generated pressure.

[0416] As an inkjet recording method, the method described in Japanese Patent Laid-Open No. 54-59936, i.e., the inkjet recording method, can be particularly effectively used. In this inkjet recording method, the ink under the action of heat energy undergoes a sharp volume change, and the force generated by this state change is used to eject the ink from the nozzle. As an inkjet recording method, the method described in paragraphs 0093 to 0105 of Japanese Patent Laid-Open No. 2003-306623 can also be applied.

[0417] In the inkjet recording method, the ink is applied to the non-permeable substrate by ejecting the ink from the nozzle of the inkjet head.

[0418] As the inkjet head method, there are: a reciprocating method in which a short-length serial head performs recording while scanning in the width direction of the recording medium; and a line type method in which a line head (Line heat) having recording elements arranged corresponding to the entire area of one side of the recording medium is used.

[0419] In the line type method, by scanning the recording medium in a direction intersecting the arrangement direction of the recording elements, image recording can be performed on the entire surface of the recording medium. In the line type method, a conveying system such as a carriage for scanning the short-strip nozzle in the reciprocating method is not required. Also, compared with the reciprocating method, in the line type method, the movement of the carriage and the complex scanning control of the recording medium are not required, and only the recording medium moves. Therefore, according to the line type method, high-speed image recording can be achieved compared with the reciprocating method.

[0420] The application of the ink is preferably performed using an inkjet head having a resolution of 300 dpi or more (more preferably 600 dpi or more, and further preferably 800 dpi or more). Here, dpi is an abbreviation for dot per inch, and 1 inch is 2.54 cm.

[0421] From the viewpoint of obtaining a high-definition image, the ink ejection amount is preferably 1 pL (picoliter) to 10 pL, and more preferably 1.5 pL to 6 pL.

[0422] <Conveying process>

[0423] The image recording method of the present invention includes a process of conveying the non-permeable substrate to which the ink is applied using a conveying member having a concavo-convex surface.

[0424] The details of the conveying member having a concavo-convex surface are as described above.

[0425] In the case of applying an ink containing water and a pigment to the non-permeable substrate, a conveying member having a concavo-convex surface is used to convey the non-permeable substrate to which the ink containing water and a pigment is applied.

[0426] In the case where the ink application process includes a process of applying a first ink onto a non-permeable substrate and a process of applying a second ink onto the non-permeable substrate onto which the first ink has been applied, in the conveying process, it is preferable to use a conveying member having an uneven surface to convey the non-permeable substrate onto which the first ink has been applied. In the conveying process, when using a conveying member having an uneven surface to convey the first ink, in the case where the application amount of the first ink per unit area relative to the non-permeable substrate is set to V, it is preferable that V, t, and A satisfy formula (1).

[0427] In addition, in the case of applying the second ink onto the non-permeable substrate onto which the first ink has been applied, a conveying member having an uneven surface can be used to convey the non-permeable substrate onto which the second ink has been applied, or other conveying members can be used for conveying.

[0428] The main cause of image unevenness is the generation of a temperature difference within the ink film during the conveying process.

[0429] If a temperature difference is generated within the ink film, the components contained in the ink will not cure uniformly, resulting in image unevenness. For example, in an ink containing water and pigments, the pigments do not cure uniformly, generating a concentration difference of pigments within the ink film, thereby causing image unevenness. Also, in an ink containing water and a flocculant (i.e., the first ink), the flocculant does not cure uniformly, generating a concentration difference of the flocculant within the first ink film. If the second ink containing water and pigments is applied onto the first ink film with a concentration difference of the flocculant, a concentration difference of pigments will be generated within the second ink film, thereby causing image unevenness.

[0430] It is considered that: in the case where there is a temperature difference between the convex portion of the conveying member and the non-permeable substrate and in the case where there is a temperature difference between the convex portion and the concave portion of the conveying member, it is easy to generate a temperature difference within the ink film. In the former case, in the non-permeable substrate, the temperature of the contact portion with the convex portion changes, and the temperature change is transmitted from the non-permeable substrate to the ink film, thereby generating a temperature difference within the ink film. In the latter case, in the non-permeable substrate, the temperature of the portion close to the concave portion changes, and the temperature change is transmitted from the non-permeable substrate to the ink film, thereby generating a temperature difference within the ink film.

[0431] From the viewpoint of suppressing image unevenness, before the conveying process is about to be carried out, the temperature difference between the convex portion of the conveying member and the non-permeable substrate is preferably 2°C or less.

[0432] And, from the viewpoint of suppressing image unevenness, before the conveying process is about to be carried out, the temperature difference between the convex portion and the concave portion of the conveying member is preferably 5°C or less.

[0433] Preferably, there is no temperature difference, and thus the lower limit value of the temperature difference is 0°C.

[0434] The temperature of the non-permeable substrate refers to the temperature of the non-permeable substrate on the side where the ink film is formed.

[0435] In addition, when the temperature of the non-permeable substrate on the side where the ink film is formed is different from the temperature of the non-permeable substrate on the side where the ink film is not formed, the average value of the two is set as the temperature of the non-permeable substrate.

[0436] The temperature of the non-permeable substrate can be measured using a non-contact infrared temperature sensor.

[0437] Moreover, the temperature of the convex and concave portions of the conveying member can also be measured using a non-contact infrared temperature sensor. However, in the case where it is difficult to measure with a non-contact infrared temperature sensor, a thermocouple or a thermal imager can be used. And, in the case where it is difficult to measure in a dynamic state immediately before the conveying process, it can be measured in a state where the conveyance is stopped.

[0438] <Heating process>

[0439] The image recording method of the present invention includes a process of heating a non-permeable substrate.

[0440] The heating process is preferably after the ink application process, and can also be before the conveying process, can be simultaneous with the conveying process, or can be after the conveying process.

[0441] In the heating process, the water in the ink applied to the non-permeable substrate evaporates to form an ink film. If the heating process is performed before the conveying process, then at the stage of conveying using a conveying member having an uneven surface, the curing of the ink film progresses to a certain extent, further suppressing image unevenness.

[0442] In addition, the method of performing the heating process simultaneously with the conveying process is, for example, the case of conveying using a conveying member having a heating mechanism.

[0443] The method of heating the non-permeable substrate is not particularly limited, and for example, methods such as irradiating infrared rays (IR), blowing warm air (for example, a hair dryer, etc.), and heating using a heating device (for example, a heater, a hot plate, a heating furnace, etc.) can be cited.

[0444] The method of heating the non-permeable substrate can be a method in which two or more of these are combined.

[0445] The heating of the non-permeable substrate can be performed from at least one of the image recording surface side and the non-image recording surface side of the non-permeable substrate.

[0446] The heating temperature is preferably 35 °C or higher, more preferably 40 °C or higher, further preferably 50 °C or higher, and particularly preferably 60 °C or higher.

[0447] The upper limit value of the heating temperature is not particularly limited, preferably 100 °C, more preferably 90 °C.

[0448] The heating time is not particularly limited, preferably 1 second to 180 seconds, more preferably 1 second to 120 seconds.

[0449] Examples

[0450] Examples of the present invention are shown below, but the present invention is not limited to the following examples.

[0451] <Preparation of the first ink>

[0452] The following components were mixed to prepare the first ink. The surface tension of the first ink was 35 mN / m.

[0453] - Composition of the first ink -

[0454] · Glutaric acid [coagulant]

[0455] …… 6.1% by mass

[0456] · Propylene glycol (PG) [water-soluble organic solvent]

[0457] …… 20% by mass

[0458] · OLFINE E1010 (manufactured by Nissin Chemical co.,ltd.) [surfactant]

[0459] …… 0.5% by mass

[0460] · SUPER FLEX 500M (DKS Co.,Ltd.) [aqueous dispersion of urethane resin particles]

[0461] …… 7.0% by mass

[0462] · Triisopropanolamine [pH adjuster]

[0463] …… 0.2% by mass

[0464] · BYK024 (BYK) [defoamer]

[0465] …… 0.01% by mass

[0466] · Ultrapure water

[0467] …… The balance to make the total of the first ink 100% by mass

[0468] <Preparation of the Second Ink (White Ink W1)>

[0469] (Preparation of White Ink W1)

[0470] The white ink W1 was prepared by mixing the components shown below. The surface tension of the white ink W1 is 35 mN / m.

[0471] - Composition of White Ink W1 -

[0472] · The following white pigment dispersion 1

[0473] …… 17% by mass based on the content of the white pigment

[0474] · Propylene glycol (PG) [Water-soluble organic solvent]

[0475] …… 28%

[0476] · Propylene glycol monomethyl ether (PGmME) [Water-soluble organic solvent]

[0477] …… 5%

[0478] · OLFINE E1010 (manufactured by Nissin Chemical co.,ltd.) [Acetylene glycol-based surfactant]

[0479] …… 0.60%

[0480] · BYK-3450 (BYK) [Silicone-based surfactant]

[0481] …… 0.75%

[0482] · BYK024 (BYK) [Defoamer]

[0483] …… 0.02%

[0484] · SOLSPERSE 43000 (manufactured by The Lubrizol Corporation) [Polymer dispersant]

[0485] …… 0.75%

[0486] · Joncryl JDX-6180 (manufactured by BASF) [Water-soluble polymer]

[0487] …… 1.1%

[0488] · PVP-K15 (Polyvinylpyrrolidone K15)

[0489] …… 0.12%

[0490] · SNOWTEX XS (manufactured by Nissan Chemical Corporation) [colloidal silica dispersion]

[0491] …… 0.1 mass% based on the content of colloidal silica particles

[0492] · Water

[0493] …… The balance to make the whole white ink W1 100 mass%

[0494] (Preparation of white pigment dispersion 1 (containing block polymer dispersant))

[0495] - Synthesis of block polymer dispersant 1 -

[0496] Referring to Synthesis Example 8 of Japanese Patent Laid-Open No. 2015-83688, block polymer dispersant 1 was synthesized as a pigment dispersant for white pigment dispersion 1. The details are shown below.

[0497] In a reaction apparatus of a 1 L separable flask equipped with a stirrer, a reflux condenser, a thermometer, and a nitrogen inlet tube, add

[0498] Diethylene glycol dimethyl ether (266 mass parts; polymerization solvent),

[0499] 2-Iodo-2-cyanopropane (6.2 mass parts; polymerization initiating compound),

[0500] Methyl methacrylate (MMA) (120 mass parts; monomer),

[0501] Acrylic acid (AA) (28.8 mass parts; monomer),

[0502] Cyclohexyl methacrylate (CHMA) (67.2 mass parts; monomer),

[0503] 2,2'-Azobis(2,4-dimethylvaleronitrile) (7.9 mass parts) and

[0504] 2-tert-Butyl-4,6-dimethylphenol (0.7 mass parts; catalyst),

[0505] While flowing nitrogen, stirring was carried out.

[0506] Next, the temperature of the mixture in the reaction apparatus (reaction temperature) was raised to 70 °C and polymerization was carried out for 3 hours to obtain a polymerization solution A containing an MMA / AA / CHMA copolymer.

[0507] After 3 hours, a part of the above polymerization solution A was sampled and the solid content was measured. As a result, it was 42.0 mass%, and it was confirmed that most of the monomers had polymerized.

[0508] Moreover, the molecular weight of the MMA / AA / CHMA copolymer was measured by GPC, and as a result, the weight-average molecular weight (Mn) was 7,500.

[0509] The acid value of the MMA / AA / CHMA copolymer was 101.0 mgKOH / g.

[0510] Next, a mixture of benzyl methacrylate (BzMA) (35.2 parts by mass; monomer) and V-65 (0.3 parts by mass; radical generator) was added to the above polymerization solution A, and polymerization was carried out at 70 °C for 3 hours to obtain a polymerization solution B containing the block polymer dispersant 1.

[0511] Here, the block polymer dispersant 1 is a block polymer containing an MMA / AA / CHMA copolymer as the A block and a BzMA homopolymer as the B block.

[0512] The solid content of the obtained polymerization solution B was measured, and the result was 43.2% by mass, and it was confirmed that most of the monomers were polymerized.

[0513] Moreover, the Mw of the block polymer dispersant 1 was 8,500, and the acid value was 89.3 mgKOH / g.

[0514] - Preparation of white pigment dispersion 1 -

[0515] The above block polymer dispersant 1 (136.4 parts by mass), butyl carbitol (163.6 parts by mass), and C.I. Pigment White 6 (trade name "JR-405", rutile-type titanium dioxide particles, manufactured by TAYCA CORPORATION) (450 parts by mass) as a white pigment were blended and stirred using a disperser. Next, the white pigment was sufficiently dispersed using a horizontal media disperser to obtain an oily pigment dispersion. The average particle diameter of the white pigment dispersed in the oily pigment dispersion was 290 nm. The viscosity of the oily pigment dispersion was 86.3 mPa·s.

[0516] Next, while stirring the above oily pigment dispersion (700 parts by mass) using a disperser, a mixed solution composed of potassium hydroxide (4.0 parts by mass) and water (341 parts by mass) was slowly added thereto and neutralized. Then, the white pigment was sufficiently dispersed using a horizontal media disperser to obtain a pigment dispersion.

[0517] Next, for the obtained pigment dispersion liquid, ultrafiltration was performed by flowing ion-exchanged water at a flow rate of 600 mL per minute using an ultrafiltration device (cross-flow type ultrafilter (UF), manufactured by Sartorius). The liquid temperature was maintained at 25°C, and ultrafiltration was performed 10 times with a volume 1 time that of the prepared liquid as one cycle. Ion-exchanged water was added to obtain white pigment dispersion liquid 1 with a white pigment concentration of 45% by mass and a concentration of block polymer dispersant 1 of 3.7% by mass.

[0518] <Preparation of Image Recording Device>

[0519] As the image recording device, the image recording device shown in Figure 1 was prepared.

[0520] As the pretreatment liquid application device for applying the first ink, a gravure coater was used.

[0521] The drying method in the pretreatment liquid drying device was set to warm air drying. 24 0.8 mm slit nozzles were arranged under the conditions of a temperature of 80°C, a wind speed of 20 m / s, and a width of 830 mm.

[0522] The ejection conditions of the second ink are as follows.

[0523] · Resolution: 1200 dpi (dot per inch (dots per inch), 1 inch is 2.54 cm) × 1200 dpi

[0524] · Ink droplet volume: 3.0 pL

[0525] <Preparation of Non-Permeable Substrate>

[0526] The following non-permeable substrates were prepared.

[0527] · Polyethylene terephthalate (PET) film "Taiko polyester film FE2001 (thickness 12 μm)", manufactured by FUTAMURACHEMICAL CO., LTD.

[0528] · Polyethylene terephthalate (PET) film "Taiko polyester film FE2001 (thickness 50 μm)", manufactured by FUTAMURACHEMICAL CO., LTD.

[0529] · Biaxially oriented polypropylene (OPP) film "Taiko polypropylene film FOR-AQ (thickness 20 μm)", manufactured by FUTAMURACHEMICAL CO., LTD.

[0530] <Preparation of Conveyor Component>

[0531] · Conveyor component H1: Figure 3BA conveying member (longitudinal groove roller) having grooves formed in a direction parallel to the conveying direction of the non-permeable substrate as shown. When the width of the smaller one of the concave and convex portions of the conveying member is set to A, a conveying member with A ranging from 30 μm to 10,000 μm is prepared.

[0532] · Conveying member H2: Figure 3C A conveying member (double spiral roller) having spiral grooves formed symmetrically from the center of the conveying member toward both ends as shown. When the width of the smaller one of the concave and convex portions of the conveying member is set to A, a conveying member with A ranging from 30 μm to 10,000 μm is prepared.

[0533] · Conveying member H3: Figure 3A A conveying member (round hole suction roller) having a plurality of round holes formed on its surface as shown. When the width of the smaller one of the concave and convex portions of the conveying member is set to A, a conveying member with A ranging from 100 μm to 5,200 μm is prepared.

[0534] <Image recording>

[0535] In Examples 1 to 11 and Comparative Examples 1 to 4, the above-described image recording apparatus, the above-described first ink, and the above-described second ink (white ink W1) were used. After applying the first ink on the non-permeable substrate, the second ink (white ink W1) was applied in a solid image shape to obtain an image recording object. The application amount per unit area of the first ink was adjusted to the values described in Table 1.

[0536] In Examples 12 to 71 and Comparative Examples 5 to 11, the above-described image recording apparatus and the above-described white ink W1 were used. The white ink W1 was applied in a solid image shape on the non-permeable substrate to obtain an image recording object. The application amount per unit area of the white ink W1 was adjusted to the values described in Table 1.

[0537] In addition, in Examples 36, 37, 39, 43, 44, and 46, the surface tension was adjusted to the values described in Table 1 by changing the content of the surfactant in the white ink W1.

[0538] In Examples 40 to 42 and 47 to 49, the surface of the biaxially stretched polypropylene (OPP) film was subjected to corona treatment, and the discharge amount was adjusted so that the surface free energy became the values described in Table 1.

[0539] The conveyance property in image recording and image unevenness in the obtained image recording object were evaluated. The evaluation method is as follows.

[0540] <Conveyance property>

[0541] The non-permeable substrate of 2,000 m was conveyed at a speed of 50 m / minute and evaluated according to the following criteria from the viewpoints of bending and conveyance damage. The amount of bending of the substrate was measured as the displacement width of the substrate edge sensor. The conveyance damage was evaluated by visually observing the degree of damage when looking through the non-image recording part of the wound non-permeable substrate. The evaluation criteria are as follows.

[0542] A: The amount of bending is within ±0.2 mm and there is no conveyance damage or the conveyance damage is 10 mm or less.

[0543] B: The amount of bending is within ±0.4 mm, and the conveyance damage exceeds 10 mm and is 20 mm or less, or the conveyance damage can only be visually recognized at a specific angle.

[0544] C: The amount of bending exceeds ±0.4 mm, or the conveyance damage exceeds 20 mm, or the conveyance damage is visually recognized regardless of the angle.

[0545] <Image non-uniformity>

[0546] An intensity gradient map of 3C (CMY) color mixing was output, and it was visually determined whether non-uniformity due to the uneven shape of the conveyance member was visually recognized in the image. The evaluation criteria are as follows.

[0547] AA: No image non-uniformity was visually recognized

[0548] A: Slight image non-uniformity was visually recognized, but it was hardly noticeable

[0549] B: The image non-uniformity was only visually recognized at a specific angle, or it was not visually recognized when the distance from the image was more than 2 m.

[0550] C: The image non-uniformity was visually recognized regardless of the angle, or it was visually recognized even when the distance from the image was more than 2 m.

[0551] The evaluation results are shown in Tables 1 to 3.

[0552] In the table, V refers to the amount applied per unit area of the ink directly applied to the non-permeable substrate. t refers to the thickness of the non-permeable substrate. A refers to the width of the one with the smaller surface area among the concave and convex parts of the conveyance member. T B / T A refers to the ratio when the larger surface area among the concave and convex parts of the conveyance member is set as T A and the smaller surface area is set as T B E1 refers to the surface free energy of the non-permeable substrate. E2 refers to the surface tension of the ink directly applied to the non-permeable substrate.

[0553] [Table 1]

[0554]

[0555] [Table 2]

[0556]

[0557] [Table 3]

[0558]

[0559] As shown in Table 1 and Table 2, it can be seen that in Examples 1 to 71, the following steps are included: applying an ink containing water onto a non-permeable substrate; using a conveying member having an uneven shape on the surface to convey the non-permeable substrate onto which the ink has been applied; and heating the non-permeable substrate. When the amount of ink applied per unit area of the non-permeable substrate is set to V (g / m 2 ), the thickness of the non-permeable substrate is set to t (μm), and the width of the concave or convex portion of the conveying member with the smaller surface area is set to A (μm), V, t, and A satisfy formula (1). Therefore, the transportability of the non-permeable substrate is excellent and unevenness of the recorded image can be suppressed.

[0560] On the other hand, in Comparative Examples 1 to 6 and Comparative Example 8, it can be seen that "(V / t)×A" is 10 or less, and the transportability of the non-permeable substrate is poor.

[0561] In Comparative Examples 7 and 9 to 11, "(V / t)×A" is 4000 or more, and unevenness of the image is visually recognized.

[0562] Next, the white pigment contained in the white ink W1 was changed to a cyan pigment, a black pigment, a magenta pigment, and a yellow pigment, respectively, to prepare a cyan ink, a black ink, a magenta ink, and a yellow ink.

[0563] Details of the cyan pigment, black pigment, magenta pigment, and yellow pigment are as follows.

[0564] · Cyan pigment: C.I.Pigment Blue 15:4, product name "Heliogen (registered trademark) Blue D7110F", manufactured by Sun Chemical (DIC) Corporation · Black pigment: carbon black, product name "MOGUL E", manufactured by CABOT Corporation

[0565] · Magenta pigment: C.I.Pigment RED 122, product name "TRM-33", manufactured by Dainichiseika Color & Chemicals Mfg. Co., Ltd.

[0566] · Yellow pigment: C.I.Pigment Yellow 185, product name "Paliotol Yellow D1155", manufactured by SunChemical (DIC)

[0567] In the above Examples 1 to 71, the white ink W1 was changed to the above cyan ink, black ink, magenta ink, and yellow ink, respectively, and image recording was performed in the same manner as in Examples 1 to 71. As a result, the same evaluation results as those obtained when using the white ink were obtained.

[0568] In addition, the entire disclosure of Japanese Patent Application No. 2022-186647 filed on November 22, 2022 is incorporated herein by reference. And all documents, patent applications, and technical standards described in this specification are incorporated herein by reference to the same extent as if each of the documents, patent applications, and technical standards incorporated by reference were specifically and separately set forth.

Claims

1. An image recording method, comprising the following steps: A step of applying an ink containing water onto a non-permeable substrate; A step of conveying the non-permeable substrate onto which the ink has been applied, using a conveying member having an uneven shape on its surface; and A step of heating the non-permeable substrate, When the amount of ink applied per unit area of the non-permeable substrate is V, the thickness of the non-permeable substrate is t, and the width of the one with a smaller surface area among the concave and convex portions of the conveying member is A, the V, the t, and the A satisfy the following formula (1), the unit of V is g / m 2 , the units of the t and the A are μm, 10 ≤ (V / t) × A ≤ 4000…(1).

2. The image recording method according to claim 1, wherein, The V, the t, and the A satisfy the following formula (2), 10 ≤ (V / t) × A ≤ 2000…(2).

3. The image recording method according to claim 1, wherein, The V, the t, and the A satisfy the following formula (3), 10 ≤ (V / t) × A ≤ 1000…(3).

4. The image recording method according to claim 1, wherein, When the surface free energy of the non-permeable substrate is set as E1, the surface tension of the ink is set as E2, and the value obtained by subtracting E2 from E1 is set as ΔE, the following formula (4) is satisfied. The units of E1 and E2 are mN / m, △E / E2 ≤ 0.50…(4).

5. The image recording method according to claim 1, wherein, When the surface free energy of the non-permeable substrate is set as E1, the surface tension of the ink is set as E2, and the value obtained by subtracting E2 from E1 is set as ΔE, the following formula (5) is satisfied. The units of E1 and E2 are mN / m, 4 ≤ (V / t) × A × (△E / E2) ≤ 1200…(5).

6. The image recording method according to claim 1, wherein, When the conveying member sets the larger surface area of the concave portion and the convex portion as T A and the smaller surface area as T B the following formula (6) is satisfied 0.08 ≤ T B / T A ≤ 0.6…(6).

7. The image recording method according to claim 1, wherein, The ink contains water and a white pigment.

8. The image recording method according to claim 1, wherein, The step of applying the ink includes the following steps: A step of applying a first ink containing water and a flocculant on the non-permeable substrate; and A step of applying a second ink containing water and a pigment on the non-permeable substrate to which the first ink has been applied, In the step of conveying, the first ink is conveyed using the conveying member, When the application amount of the first ink per unit area with respect to the non-permeable substrate is set as the V, the V, the t, and the A satisfy the formula (1).

Images