Inkjet recording method

Abstract

An ink jet recording method including: a step of applying a pretreatment liquid, which contains water, a coagulant having a molecular weight of 1000 or less, and a resin, to an impermeable substrate; a pretreatment liquid drying process; a step of applying a first ink containing water and a colorant to the impermeable substrate to which the pretreatment liquid has been applied by an ink jet recording method; a step of drying the first ink under drying conditions of a wind speed of V m / sec, a drying temperature of T DEG C, and a drying time of t sec; and a second ink application step in which V, T, t, M, and P satisfy the following formulae (1) and (2), where M mass% is the content of the coagulant relative to the total amount of the pretreatment liquid, and P mass% is the content of the resin relative to the total amount of the pretreatment liquid. (1) 3500 > = 50V + TtM / P > = 700, and (2) 120 > = T > = 25.

Description

Technical Field

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

[0002] Conventionally, various studies have been conducted on inkjet inks and inkjet recording methods.

[0003] For example, Japanese Patent Gazette No. 2019-177553 discloses a liquid discharging method, which is a liquid discharging method using a line head type, and is characterized in that it includes: a treatment liquid imparting process, in which a treatment liquid is imparted to a non-permeable substrate; a first discharging process, in which a first ink containing an organic solvent is discharged to the non-permeable substrate to which the treatment liquid has been imparted; a first heating process, in which the non-permeable substrate to which the first ink has been discharged is heated with infrared rays; and a second discharging process, in which a second ink containing an organic solvent is discharged to the heated non-permeable substrate, wherein the content ratio of the organic solvent contained in the first ink is greater than the content ratio of the organic solvent contained in the second ink.

[0004] In addition, Japanese Patent Gazette No. 2021-4368 discloses an ink set comprising: a reaction liquid containing a coagulant; a first ink containing a colorant; and a second ink containing a colorant, the ink set being used for recording on a non-absorbent recording medium or a low-absorbent recording medium, and the reaction liquid, the first ink, and the second ink are sequentially overlapped on the recording medium for use. Summary of the invention

[0005] Technical issues to be solved by the invention

[0006] However, conventionally, it has been difficult to achieve both continuous ink ejection properties in an inkjet recording method and blocking resistance of an image in an image recorded by the inkjet recording method.

[0007] The present invention has been made in view of such circumstances, and an object of the embodiments of the present invention is to provide an inkjet recording method capable of recording an image having excellent continuous ink ejection properties and excellent anti-blocking properties.

[0008] Means for solving technical problems

[0009] The present invention includes the following aspects.

[0010] <1>

[0011] An inkjet recording method comprising:

[0012] A step of applying a pretreatment liquid containing water, a coagulant with a molecular weight of 1000 or less, and a resin to an impermeable substrate;

[0013] A process of drying the pretreatment liquid;

[0014] A step of applying a first ink containing water and a colorant to an impermeable substrate to which a pretreatment liquid has been applied by an inkjet recording method;

[0015] A step of drying the first ink under drying conditions of wind speed V m / s, drying temperature T°C, and drying time t seconds; and

[0016] A process of applying a second ink containing water and a colorant to an impermeable substrate to which a pretreatment liquid and a first ink have been applied by an inkjet recording method,

[0017] When the content of the coagulant relative to the total amount of the pretreatment liquid is M mass % and the content of the resin relative to the total amount of the pretreatment liquid is P mass %, V, T, t, M and P satisfy the following formulas (1) and (2).

[0018] 3500≥50V+TtM / P≥700……(1)

[0019] 120≥T≥25……(2)

[0020] <2>

[0021] The inkjet recording method according to <1>, wherein

[0022] V, T, t, M, and P satisfy the following formula (1A).

[0023] 3000≥50V+TtM / P≥1000……(1A)

[0024] <3>

[0025] The inkjet recording method according to <1> or <2>, wherein:

[0026] In the process of drying the pre-treatment liquid, at the wind speed V p m / s, drying temperature T p ℃, drying time t p The pretreatment liquid is dried under the drying conditions of 10 seconds.

[0027] V, T, t, M, P, V p 、T p and t p The following formula (3) is satisfied.

[0028] 3500≥20V p +50V+(Tt+T p t p )M / P≥1500……(3)

[0029] <4>

[0030] The inkjet recording method according to any one of <1> to <3>, wherein when the tension of the non-permeable substrate is defined as S (N / m), V, T, t, M, P, and S satisfy the following formula (4).

[0031] 50≥(50V+TtM / P) / S≥15……(4)

[0032] <5>

[0033] The inkjet recording method according to any one of <1> to <4>, wherein the amount of the coagulant applied to the non-permeable substrate is 0.03 g / m 2 ~0.15g / m 2 .

[0034] <6>

[0035] The inkjet recording method according to any one of <1> to <5>, wherein when the glass transition temperature of the resin contained in the pretreatment liquid is Tg° C., T, t, and Tg satisfy the following formula (5).

[0036] 1500≥(T-Tg)t≥200……(5)

[0037] Effects of the Invention

[0038] According to the present invention, there is provided an inkjet recording method capable of recording an image having excellent continuous ink ejection properties and excellent anti-blocking properties. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 This is a diagram for explaining the details of the evaluation criteria of image quality in the embodiment. DETAILED DESCRIPTION

[0040] In the present invention, a numerical range expressed using "to" indicates a range including the numerical values ​​before and after "to" as the minimum value and the maximum value, respectively.

[0041] In the present invention, when a plurality of substances corresponding to each component are present in the composition, the amount of each component in the composition represents the total amount of the plurality of substances present in the composition unless otherwise specified.

[0042] In the numerical ranges described stepwise in the present invention, the upper limit or lower limit described in a certain numerical range may be replaced by the upper limit or lower limit of another numerical range described stepwise, or may be replaced by the value shown in the Examples.

[0043] In the present invention, the term "process" includes not only independent processes but also processes that cannot be clearly distinguished from other processes as long as the intended purpose of the process can be achieved.

[0044] In the present invention, the concept of "image" includes not only pattern images (eg, characters, symbols, or graphics) but also solid images.

[0045] In the present invention, "(meth)acrylic acid" is a concept including both acrylic acid and methacrylic acid.

[0046] [Inkjet recording method]

[0047] The inkjet recording method of the present invention comprises: a step of applying a pretreatment liquid containing water, a coagulant with a molecular weight of 1000 or less, and a resin to an impermeable substrate (hereinafter, also referred to as a "pretreatment liquid applying step"); a step of drying the pretreatment liquid (hereinafter, also referred to as a "pretreatment liquid drying step"); a step of applying a first ink containing water and a colorant to the impermeable substrate to which the pretreatment liquid has been applied by an inkjet recording method (hereinafter, also referred to as a "first ink applying step"); and a step of drying the pretreatment liquid at a wind speed of V m / s, a drying temperature of T°C, and a drying time of T°C. A process of drying the first ink under a drying condition of t seconds (hereinafter also referred to as "the first ink drying process"); and a process of imparting a second ink containing water and a colorant to an impermeable substrate to which a pretreatment liquid and the first ink have been imparted by an inkjet recording method (hereinafter also referred to as "the second ink imparting process"), when the content of the coagulant relative to the total amount of the pretreatment liquid is set to M mass %, and the content of the resin relative to the total amount of the pretreatment liquid is set to P mass %, V, T, t, M and P satisfy the following formulas (1) and (2).

[0048] 3500≥50V+TtM / P≥700……(1)

[0049] 120≥T≥25……(2)

[0050] According to the inkjet recording method of the present invention, an image having excellent continuous ink ejection properties and excellent anti-blocking properties can be obtained. The reason why such an effect can be exerted is presumed to be as follows.

[0051] In the inkjet recording method of the present invention, a pretreatment liquid, a first ink, and a second ink are sequentially applied to an impermeable substrate. In the past, in the method of applying the pretreatment liquid, the first ink, and the second ink, the continuous discharge property of the second ink in particular tended to decrease. It is believed that the reason is that the coagulant contained in the pretreatment liquid is easily scattered in the process of drying the first ink, and the scattered coagulant adheres to the nozzle for applying the second ink. In particular, it was found that when an impermeable substrate is used, the coagulant tends to be more easily scattered than when a permeable substrate is used.

[0052] Furthermore, in the conventional method of applying the pretreatment liquid, the first ink, and the second ink, if the drying is insufficient, the anti-blocking property of the obtained image tends to be poor. However, if the drying is only enhanced, the coagulant is easy to scatter, so it is difficult to achieve both continuous ejection properties and the anti-blocking property of the obtained image.

[0053] In contrast, the inventors of the present invention paid attention to the wind speed, temperature, drying time, and content of the coagulant relative to the total amount of the pretreatment liquid and the content of the resin relative to the total amount of the pretreatment liquid in the first ink drying step, and found that by satisfying the above-mentioned formulas (1) and (2), both the continuous ejection property and the anti-blocking property of the obtained image can be achieved.

[0054] Japanese Patent Application Publication No. 2019-177553 and Japanese Patent Application Publication No. 2021-4368 do not focus on the specific conditions in the first ink drying step.

[0055] Hereinafter, the formula (1) and the formula (2) in the present invention will be described.

[0056] <Formula (1), Formula (2)>

[0057] In the inkjet recording method of the present invention, when the wind speed in the first ink drying step is set to V m / s, the drying temperature is set to T°C, the drying time is set to t seconds, the content of the coagulant relative to the total amount of the pretreatment liquid is set to M mass%, and the content of the resin relative to the total amount of the pretreatment liquid is set to P mass%, V, T, t, M and P satisfy equations (1) and (2).

[0058] 3500≥50V+TtM / P≥700……(1)

[0059] 120≥T≥25……(2)

[0060] V, T and t in formula (1) are parameters related to the drying process of the first ink. The larger the value, the stronger the drying strength. In addition, "M / P" in formula (1) is the ratio of the content of the resin to the content of the coagulant contained in the pretreatment liquid. The larger the value of "M / P", that is, when the content of the coagulant is large relative to the content of the resin, it means that it is easier to dry. If the value calculated by "50V+TtM / P" is 3500 or less, the scattering of the coagulant is suppressed and the continuous ejection of the second ink is excellent. On the other hand, if the value calculated by "50V+TtM / P" is 700 or more, the pretreatment liquid and the first ink are properly dried and the anti-blocking property is excellent.

[0061] The first drying process may include a plurality of drying processes having at least one of wind speed, drying temperature and drying time that is different from each other. For example, when the first drying process includes n stages of drying processes, the wind speeds in the first to n stages of drying processes are respectively set to V 1 、V 2 ,……,V n , the drying temperatures in the first to nth drying steps are respectively set to T 1 、T 2 ,……,T n , the drying time in the first to nth drying steps is t 1 ,t 2 ,……,t n .

[0062] V, T and t in the formula (1) are calculated by the following formulas: Let i be 1 to n.

[0063] V=Σ(V i t i ) / Σ(t i )

[0064] T=Σ(T i t i ) / Σ(t i )

[0065] t=Σ(t i )

[0066] For example, when the first drying step is a two-stage drying step, V, T, and t in the formula (1) are calculated by the following formula.

[0067] V=(V 1 t 1 +V 2 t 2 ) / (t 1 +t 2 )

[0068] T=(T 1 t 1 +T 2 t 2 ) / (t 1 +t 2 )

[0069] t=t 1 +t 2

[0070] From the viewpoint of further improving the continuous ejection property, the upper limit value of "50V+TtM / P" is preferably 3000. On the other hand, from the viewpoint of further improving the anti-blocking property, the lower limit value of "50V+TtM / P" is preferably 1000.

[0071] Therefore, from the viewpoint of further improving the continuous ejection property and the anti-blocking property, V, T, t, M, and P preferably satisfy the formula (1A).

[0072] 3000≥50V+TtM / P≥1000……(1A)

[0073] V, T, t, M, and P are not particularly limited as long as they satisfy the formula (1) and the formula (2), but preferred ranges are as follows.

[0074] 〔V〕

[0075] The wind speed in the first ink drying step is preferably 5 m / sec to 50 m / sec, and more preferably 10 m / sec to 30 m / sec.

[0076] In the present invention, the wind speed in the first ink drying process is measured at the position of the non-permeable substrate using a high wind speed thermal anemometer (product name "M261-NTS-TA200S", manufactured by Shiro Sangyou Co., Ltd.).

[0077] 〔T〕

[0078] The drying temperature in the first ink drying step is 25°C to 120°C, preferably 40°C to 100°C, and more preferably 60°C to 80°C.

[0079] In the present invention, the drying temperature in the first ink drying process is measured at the position of the non-permeable substrate using a high-speed thermal anemometer (product name "M261-NTS-TA200S", manufactured by Shiro Sangyou Co., Ltd.).

[0080] 〔t〕

[0081] The drying time in the first ink drying step is preferably 5 seconds to 40 seconds, and more preferably 10 seconds to 25 seconds.

[0082] 〔M〕

[0083] The content of the coagulant relative to the total amount of the pretreatment liquid is preferably 2% by mass to 15% by mass, and more preferably 5% by mass to 10% by mass.

[0084] 〔P〕

[0085] The content of the resin relative to the total amount of the pretreatment liquid is preferably 2% by mass to 15% by mass, and more preferably 5% by mass to 10% by mass.

[0086] <Formula (3)>

[0087] In the inkjet recording method of the present invention, it is preferred that in the pre-treatment liquid drying step, the wind speed V p m / s, drying temperature T p ℃, drying time t p The pretreatment liquid is dried under the drying conditions of 1000 s, and V, T, t, M, P, V p 、T p and t p Satisfies formula (3).

[0088] 3500≥20V p +50V+(Tt+T p t p )M / P≥1500……(3)

[0089] V in formula (3) p 、T p and t p It is a parameter related to the drying process of the pretreatment liquid. The larger the value, the stronger the drying intensity. p +50V+(Tt+T p t p )M / P" is 3500 or less, the scattering of the coagulant is suppressed, and the continuous ejection property of the second ink is excellent. On the other hand, if the value calculated by "20V p +50V+(Tt+T p t p )M / P" calculated value is 1500 or more, the pretreatment liquid and the first ink are properly dried and the anti-blocking property is excellent.

[0090] The pretreatment liquid drying process may include a plurality of drying processes with different wind speeds, drying temperatures, and drying times. For example, when the pretreatment liquid drying process includes n stages of drying processes, the wind speeds in the first to nth stages of drying processes are set to V, V, and V, respectively. p 1 、V p 2 ,……,V p n , the drying temperatures in the first to nth drying steps are respectively set to T p 1 、T p 2 ,……,T p n , the drying time in the first to nth drying steps is t p 1 ,t p 2 ,……,t p n .

[0091] V in formula (3) p 、T p and t p It is calculated by the following formula: i is set to 1 to n.

[0092] V p =Σ(V p i t i ) / Σ(t p i )

[0093] T p =Σ(T p i t i ) / Σ(t p i )

[0094] t p =Σ(t p i )

[0095] For example, when the first drying step is a two-stage drying step, V in formula (3) is p 、T p and t p Calculated by the following formula.

[0096] V p =(V p 1 t p 1 +V p 2 t p 2 ) / (t p 1 +t p 2 )

[0097] T p =(T p 1 t p 1 +T p 2 t p 2 ) / (t p 1 +t p 2 )

[0098] t p =t p 1 +t p 2

[0099] V p 、T p and t p There are no particular limitations as long as the formula (3) is satisfied, but the preferred ranges are as follows.

[0100] 〔V p 〕

[0101] The wind speed in the pretreatment liquid drying step is preferably 5 m / sec to 20 m / sec, more preferably 10 m / sec to 20 m / sec.

[0102] In the present invention, the wind speed in the drying process of the pretreatment liquid is measured using a high wind speed thermal anemometer (product name "M261-NTS-TA200S", manufactured by Shiro Sangyou Co., Ltd.) at the position of the non-permeable substrate.

[0103] 〔T p 〕

[0104] The drying temperature in the pretreatment liquid drying step is preferably 25°C to 100°C, more preferably 60°C to 80°C.

[0105] In the present invention, the drying temperature in the pretreatment liquid drying process is measured using a high-speed thermal anemometer (product name "M261-NTS-TA200S", manufactured by Shiro Sangyou Co., Ltd.) at the position of the non-permeable substrate.

[0106] 〔t p 〕

[0107] The drying time in the pretreatment liquid drying step is preferably 0.5 to 5 seconds, more preferably 1 to 3 seconds.

[0108] <Formula (4)>

[0109] In the inkjet recording method of the present invention, when the tension of the non-permeable substrate is defined as S (N / m), it is preferred that V, T, t, M, P, and S satisfy the formula (4).

[0110] 50≥(50V+TtM / P) / S≥15……(4)

[0111] In the present invention, the tension of the impermeable substrate refers to the tension of the impermeable substrate at the time of applying the pretreatment liquid. In addition, from the viewpoint of suppressing the generation of wrinkles and sagging in the impermeable substrate, the tension of the impermeable substrate in the pretreatment liquid applying step, the pretreatment liquid drying step, the first ink applying step, the first ink drying step, and the second ink applying step is preferably constant.

[0112] In the inkjet recording method of the present invention, each step is preferably performed while conveying the long non-permeable substrate.

[0113] When the long impermeable substrate is conveyed, the tension can be adjusted by a tension control mechanism of a conveying device for conveying the impermeable substrate.

[0114] From the viewpoint of suppressing the occurrence of wrinkles, sagging, and the like in the impermeable substrate, the tension of the impermeable substrate is preferably set according to the material, thickness, and the like of the impermeable substrate.

[0115] If the value calculated by "(50V+TtM / P)S" is 15 or more, the pressure on the non-permeable substrate is reduced when the non-permeable substrate is rolled up after image recording, and the anti-blocking property is excellent. On the other hand, if the value calculated by "(50V+TtM / P)S" is 50 or less, the shaking of the non-permeable substrate is suppressed, and the scattering of the coagulant is suppressed accordingly, and the continuous ejection property of the second ink is improved.

[0116] S is not particularly limited as long as it satisfies the formula (4), but a preferred range is as follows.

[0117] 〔S〕

[0118] The tension of the impermeable substrate is preferably 40 N / m to 120 N / m, more preferably 60 N / m to 100 N / m.

[0119] <Formula (5)>

[0120] In the inkjet recording method of the present invention, when the glass transition temperature of the resin contained in the pretreatment liquid is Tg° C., it is preferred that T, t, and Tg satisfy the formula (5).

[0121] 1500≥(T-Tg)t≥200……(5)

[0122] In the present invention, the glass transition temperature of the resin is referred to as an actually measured value.

[0123] Specifically, the glass transition temperature of the resin is a value measured under normal measurement conditions using a differential scanning calorimeter (DSC) EXSTAR6220 manufactured by SII Nanotechnology Inc. However, when measurement is difficult due to decomposition of the resin, etc., a calculated value calculated by the following calculation formula is applied. The calculated value (Tg) is calculated by the following formula (A).

[0124] 1 / Tg=Σ(Xi / Tgi)……(A)

[0125] Here, the resin to be calculated is copolymerized by n monomer components from i=1 to n. Xi is the mass fraction of the i-th monomer (ΣXi=1), and Tgi is the glass transition temperature (absolute temperature) of the homopolymer of the i-th monomer. Here, Σ is the sum of i=1 to n. In addition, the value of the glass transition temperature (Tgi) of the homopolymer of each monomer adopts the value of Polymer Handbook (Polymer Handbook) (3rd edition) (J. Brandrup, EH Immergut (Wiley-Interscience, 1989).

[0126] If the value calculated by "(T-Tg)t" is 200 or more, the scattering of the resin coagulant contained in the pretreatment liquid is suppressed, and the continuous discharge property of the second ink is improved. On the other hand, if the value calculated by "(T-Tg)t" is 1500 or less, the anti-blocking property is improved.

[0127] Hereinafter, each step of the inkjet recording method of the present invention will be described.

[0128] <Pre-treatment liquid application step>

[0129] In the pretreatment liquid application step, a pretreatment liquid containing water, a coagulant having a molecular weight of 1,000 or less, and a resin is applied to the impermeable substrate.

[0130] (Impermeable substrate)

[0131] In the present invention, the impermeability of the impermeable substrate refers to a property in which the water absorption rate within 24 hours measured according to ASTM D570-98 (2018) is 2.5% or less. Here, the "%" as a unit of 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.

[0132] Examples of materials for the non-permeable substrate include glass, metals (e.g., aluminum, zinc, copper, etc.) and resins (e.g., polyvinyl chloride, cellulose diacetate, cellulose triacetate, cellulose propionate, cellulose butyrate, cellulose acetate butyrate, cellulose nitrate, polyethylene terephthalate, polyethylene, polystyrene, polypropylene, polycarbonate, polyvinyl acetal, nylon, acrylic resin, etc.).

[0133] The material of the impermeable substrate is preferably a resin. That is, the impermeable substrate is preferably a resin substrate.

[0134] Among them, from the viewpoint of versatility, the material of the impermeable substrate is preferably polypropylene, polyethylene, polyethylene terephthalate, nylon, acrylic resin or polyvinyl chloride.

[0135] The shape of the impermeable substrate is preferably a sheet (film) or plate. Examples of the impermeable substrate having such a shape include 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.

[0136] Examples of the resin-made impermeable substrate include resin sheets (resin films), and specific examples include flexible packaging materials for packaging food and the like, and floor guides for large retail stores.

[0137] Examples of the impermeable substrate include sheet-shaped (film-shaped) or plate-shaped impermeable substrates and woven fabrics (textiles) and nonwoven fabrics formed of impermeable fibers.

[0138] The thickness of the impermeable substrate is preferably 0.1 μm to 1,000 μm, more preferably 0.1 μm to 800 μm, and further preferably 1 μm to 500 μm.

[0139] For the non-permeable substrate, a hydrophilic treatment can be implemented. As the hydrophilic treatment, corona treatment, plasma treatment, frame treatment, heat treatment, abrasion treatment, light irradiation treatment (such as UV treatment) and flame treatment can be cited, but it is not limited to these. Corona treatment can be carried out using a corona treatment machine (Corona Master) (product name "PS-10S", manufactured by Shinko Electric & Instrumentation Co., Ltd.). The conditions of the corona treatment can be appropriately selected according to the type of the non-permeable substrate.

[0140] The impermeable substrate may be a transparent impermeable substrate.

[0141] 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).

[0142] When the impermeable substrate is a transparent impermeable substrate, the image can be easily visually recognized through the impermeable substrate from the image non-recording surface side of the impermeable substrate.

[0143] For example, when the impermeable substrate is a transparent impermeable substrate, it is preferable to use a color ink as the first ink described below and a white ink as the second ink described below. If an image is recorded by sequentially applying the pretreatment liquid, the first ink, and the second ink to the impermeable substrate, it is easy to visually recognize a color image (e.g., a pattern image such as a character or a graphic) with a white image (e.g., a solid image) as a background through the impermeable substrate from the image non-recording surface side of the impermeable substrate.

[0144] (Pretreatment liquid)

[0145] The pretreatment liquid contains water, a coagulant having a molecular weight of 1000 or less, and a resin.

[0146] -water-

[0147] The pretreatment liquid contains water.

[0148] For example, the content of water can be set to 50% by mass to 90% by mass based on the total amount of the pretreatment liquid.

[0149] 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 pretreatment liquid.

[0150] The upper limit of the water content also depends on the amounts 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 pretreatment liquid.

[0151] - Coagulants -

[0152] The pretreatment liquid contains at least one coagulant having a molecular weight of 1,000 or less.

[0153] The coagulant in the pretreatment liquid aggregates the components of the first ink and the second ink on the non-permeable substrate, thereby improving the image quality.

[0154] The coagulant is not particularly limited as long as it is a compound having a molecular weight of not more than 1000. The molecular weight is calculated based on the types and numbers of atoms constituting the compound.

[0155] The coagulant is preferably at least one selected from the group consisting of organic acids, polyvalent metal compounds, and metal complexes.

[0156] Preferred examples of the coagulant include those described in paragraphs 0122 to 0129 of International Publication No. 2020 / 195360.

[0157] Hereinafter, preferred embodiments of each of the organic acid, the polyvalent metal compound, and the metal complex that can be used as the coagulant will be described.

[0158] --Organic Acids--

[0159] Examples of the organic acid include organic compounds having an acidic group.

[0160] Examples of the acidic group include a phosphoric acid group, a phosphonic acid group, a phosphinic acid group, a sulfuric acid group, a sulfonic acid group, a sulfonic acid group, a sulfinic acid group, and a carboxyl group.

[0161] Among them, from the viewpoint of the aggregation speed of the ink, the acidic group is preferably a phosphoric acid group or a carboxyl group, and more preferably a carboxyl group.

[0162] It is preferred that at least a part of the acidic groups be dissociated in the pretreatment liquid.

[0163] 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, pyranonecarboxylic acid, pyrrolecarboxylic acid, furancarboxylic acid, pyridinecarboxylic acid, coumaric acid, thiophenecarboxylic acid and nicotinic acid.

[0164] Among them, from the viewpoint of the aggregation speed of the ink, the organic compound having a carboxyl group is preferably a divalent or higher-valent carboxylic acid (hereinafter also referred to as a polyvalent carboxylic acid), and more preferably a dicarboxylic acid.

[0165] 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.

[0166] The organic acid preferably has a low pKa (eg, 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 can be reduced by contact with an organic acid with a lower pKa, thereby reducing dispersion stability.

[0167] The organic acid preferably has a low pKa, high solubility in water, and a valence of divalent or more. Furthermore, the organic acid more preferably has a high buffering capacity in a pH region lower than the pKa of the functional group (eg, carboxyl group) for stabilizing particle dispersion in the ink.

[0168] --Multivalent Metal Compounds--

[0169] Examples of the polyvalent metal compound include polyvalent metal salts.

[0170] Examples of the polyvalent metal salt include organic acid polyvalent metal salts and inorganic acid polyvalent metal salts.

[0171] 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.

[0172] As the inorganic acid polyvalent metal salt, a nitrate polyvalent metal salt, a hydrochloride polyvalent metal salt or a thiocyanate polyvalent metal salt is preferred.

[0173] Examples of polyvalent metal salts include salts of alkaline earth metals of Group 2 of the periodic table (e.g., magnesium and calcium), salts of transition metals of Group 3 of the periodic table (e.g., lanthanum), salts of metals of Group 13 of the periodic table (e.g., aluminum), and salts of lanthanides (e.g., neodymium).

[0174] 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.

[0175] 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.

[0176] It is preferred that at least a part of the polyvalent metal compound is dissociated into polyvalent metal ions and counter ions in the pretreatment liquid.

[0177] --Metal Complexes--

[0178] The metal complex preferably contains at least one selected from the group consisting of zirconium, aluminum, and titanium as a metal element.

[0179] The metal complex is preferably a metal complex containing as a ligand at least one selected from the group consisting of acetate, acetylacetonate, methyl acetoacetate, ethyl acetoacetate, octylene glycolate, butoxyacetylacetonate, lactate, lactate ammonium salt and triethanolamineate.

[0180] The metal complex may be a commercially available product. Various organic ligands, in particular various multidentate ligands capable of forming metal chelate catalysts, are available on the market. Therefore, the metal complex may be a metal complex prepared by combining commercially available organic ligands and metals.

[0181] -Resin-

[0182] The pretreatment liquid contains at least one resin.

[0183] The resin in the pretreatment liquid contributes to the film-forming property of the pretreatment liquid (ie, the formability of the pretreatment liquid film).

[0184] The weight average molecular weight (Mw) of the resin is preferably 1,000 to 300,000, more preferably 2,000 to 200,000, and further preferably 5,000 to 100,000.

[0185] In the present invention, unless otherwise specified, the weight average molecular weight (Mw) refers to a value measured by gel permeation chromatography (GPC).

[0186] In the measurement based on gel permeation chromatography (GPC), HLC (registered trademark)-8020GPC (Tosoh Corporation) was used as a measuring device, 3 TSKgel (registered trademark) Super Multipore HZ-H (4.6 mmID×15 cm, Tosoh Corporation) were used as columns, and THF (tetrahydrofuran) was used as an eluent. In addition, as measurement conditions, the sample concentration was set to 0.45 mass%, the flow rate was set to 0.35 ml / min, the sample injection amount was set to 10 μl, and the measurement temperature was set to 40° C., and the measurement was performed using an RI detector.

[0187] The calibration curve was prepared using eight samples of "TSK standard, polystyrene" manufactured by Tosoh Corporation: "F-40", "F-20", "F-4", "F-1", "A-5000", "A-2500", "A-1000" and "n-propylbenzene".

[0188] From the viewpoint of the temporal stability of the pretreatment liquid, the resin in the pretreatment liquid is preferably present in a particle form. That is, the resin in the pretreatment liquid is preferably in the form of resin particles.

[0189] The resin constituting the resin particles is preferably a water-insoluble resin. The "water-insoluble" in the water-insoluble resin refers to a property that the amount of the water-insoluble resin dissolved in 100 g of distilled water at 25°C is less than 2 g.

[0190] The volume average particle size of the resin particles is preferably 1 nm to 300 nm, more preferably 3 nm to 200 nm, and even more preferably 5 nm to 150 nm.

[0191] In the present invention, the volume average particle size refers to a value measured using a laser diffraction / scattering particle size distribution analyzer.

[0192] As a measuring device, for example, a particle size distribution measuring device "Microtrac MT-3300II" (manufactured by Nikkiso Co., Ltd.) can be cited.

[0193] The resin particles are preferably at least one selected from the group consisting of acrylic resin particles, ester resin particles, a mixture of acrylic resin particles and ester resin particles, composite particles containing acrylic resin and ester resin, styrene acrylic resin particles, and polyurethane resin particles.

[0194] In the present invention, acrylic resin refers to a polymer (homopolymer or copolymer) containing at least one raw material monomer selected from the group consisting of acrylic acid, acrylic acid derivatives (eg, acrylic esters), methacrylic acid, and methacrylic acid derivatives (eg, methacrylic esters).

[0195] Regarding the resin particles, for example, paragraphs 0038 to 0114 of International Publication No. 2021 / 192720, paragraphs 0109 to 0120 of Japanese Patent Application Laid-Open No. 2015-25076, and the like can be referred to.

[0196] -Water-soluble organic solvents-

[0197] The pretreatment liquid may contain at least one water-soluble organic solvent.

[0198] In the present invention, the "water-soluble" in the "water-soluble organic solvent" means a property that 1 g or more of the solvent dissolves in 100 g of water at 25°C.

[0199] The type of water-soluble organic solvent is not limited, and examples thereof include monoalcohols having 1 to 4 carbon atoms;

[0200] 1,3-propylene glycol, 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 and other diols;

[0201] Triols such as glycerol, 1,2,6-hexanetriol, and trimethylolpropane;

[0202] Alkylene glycols such as ethylene glycol and propylene glycol;

[0203] Alkylene glycol monoalkyl ethers such as ethylene glycol monoalkyl ether and propylene glycol monoalkyl ether;

[0204] Polyalkylene glycols such as diethylene glycol, triethylene glycol, tetraethylene glycol, pentaethylene glycol, dipropylene glycol, polyoxyethylene polyoxypropylene glycol, etc.;

[0205] Polyalkylene glycol ethers such as diethylene glycol monoalkyl ether, triethylene glycol monoalkyl ether, tripropylene glycol monoalkyl ether, polyoxypropylene glycerol ether, and the like; and

[0206] 2-Pyrrolidone, N-methyl-2-pyrrolidone.

[0207] From the viewpoint of the drying property and temporal stability of the pretreatment liquid, the water-soluble organic solvent in the pretreatment liquid preferably contains at least one selected from the group consisting of alkylene glycols and alkylene glycol monoalkyl ethers.

[0208] The content of the water-soluble organic solvent is preferably 1% by mass to 20% by mass, more preferably 2% by mass to 10% by mass, based on the total amount of the pretreatment liquid.

[0209] -additive-

[0210] The pretreatment liquid 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 an alkaline compound as required.

[0211] -Physical properties-

[0212] The pH of the pretreatment liquid is preferably 2.0 to 7.0, more preferably 2.0 to 4.0.

[0213] The pH is measured at 25° C. using a pH meter, for example, using the product name “WM-50EG” manufactured by DKK-TOA CORPORATION.

[0214] From the viewpoint of coating properties of the pretreatment liquid, the viscosity of the pretreatment liquid is preferably 0.5 mPa·s to 10 mPa·s, and more preferably 1 mPa·s to 5 mPa·s.

[0215] The viscosity is measured at 25° C. using a viscometer, for example, a TV-22 model viscometer manufactured by Toki Sangyo Co., Ltd.

[0216] The surface tension of the pretreatment liquid 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.

[0217] The surface tension is measured at 25° C. using a surface tensiometer, for example, by a flat plate method using an automatic surface tensiometer manufactured by Kyowa Interface Science Co., Ltd. (product name “CBVP-Z”).

[0218] (Method of applying pretreatment liquid)

[0219] The method for applying the pretreatment liquid is not particularly limited, and examples thereof include known methods such as a coating method, a dipping method, and an inkjet recording method.

[0220] Examples of the coating method include known coating methods using a bar coater, an extrusion die coater, an air knife coater, a blade coater, a rod coater, a knife coater, an extrusion coater, a reverse roll coater, and the like.

[0221] In the pretreatment liquid application step, the amount of the coagulant applied to the impermeable substrate is preferably 0.03 g / m 2 ~0.15g / m2 , more preferably 0.06 g / m 2 ~0.12g / m 2 .

[0222] The amount of coagulant applied is per 1m 2 Area mass (g / m 2 ).

[0223] The amount of coagulant applied can be determined by the amount of pretreatment solution applied (g / m 2 ) and the content (mass %) of the coagulant contained in the pretreatment liquid. The amount of the coagulant applied can be adjusted by adjusting at least one of the amount of the pretreatment liquid applied and the content of the coagulant contained in the pretreatment liquid.

[0224] If the amount of coagulant applied is 0.03 g / m 2 If the amount of the coagulant applied is 0.15 g / m 2 Below, the scattering of the coagulant is suppressed, and the continuous discharge property of the second ink is improved.

[0225] <Pre-treatment liquid drying process>

[0226] In the pretreatment liquid drying step, the pretreatment liquid is dried.

[0227] The drying method of the pretreatment liquid is not particularly limited, and examples thereof include infrared (IR) drying, air drying (e.g., a dryer, etc.), and heating drying using a heating device (e.g., a heater, a hot plate, a heating furnace, etc.). Two or more of these drying methods may be combined.

[0228] As described above, it is preferred that in the pretreatment liquid drying step, the wind speed V p m / s, drying temperature T p ℃, drying time t p The pretreatment liquid is dried under the drying conditions of 1000 s, and V, T, t, M, P, V p 、T p and t p Satisfies formula (3).

[0229] The wind speed is preferably greater than 0 m / s, that is, the drying method of the pretreatment liquid is preferably air drying. The air supply to the pretreatment liquid can be performed using, for example, a blower. The air sent from the blower can be cold air or warm air.

[0230] Preferred aspects of the wind speed, drying temperature, and drying time in the pretreatment liquid drying step are as described above.

[0231] <First ink application step>

[0232] In the first ink applying step, a first ink containing water and a colorant is applied by an inkjet recording method onto the non-permeable substrate to which the pre-treatment liquid has been applied.

[0233] -water-

[0234] The first ink contains water.

[0235] For example, the content of water can be set to 10% by mass to 99% by mass relative to the total amount of the first ink.

[0236] The content of water is preferably 10% by mass or more, more preferably 20% by mass or more, further preferably 30% by mass or more, and particularly preferably 50% by mass or more, relative to the total amount of the first ink.

[0237] The upper limit of the water content also depends on the amounts of other components, but is, for example, 99% by mass, preferably 95% by mass, and more preferably 90% by mass, relative to the total amount of the first ink.

[0238] -pigment-

[0239] The first ink contains a colorant.

[0240] Preferably, one of the first ink and the second ink is a white ink showing white, and the other is a colored ink showing a color other than white. In other words, preferably, one of the first ink and the second ink contains a white pigment, and the other contains a pigment other than white pigment.

[0241] The pigment may be any of commercially available organic pigments and inorganic pigments.

[0242] Examples of the pigment include those described in "Encyclopedia of Pigments" edited by Seishiro Ito (2000), "Industrial Organic Pigments" by W. Herbst, K. Hunger, JP-A-2002-12607, JP-A-2002-188025, JP-A-2003-26978, and JP-A-2003-342503.

[0243] 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.

[0244] The white pigment is preferably titanium dioxide, barium sulfate, calcium carbonate or zinc oxide, more preferably titanium dioxide.

[0245] From the viewpoint of concealability, the average primary particle size of the white pigment is preferably 150 nm or more, more preferably 200 nm or more, and from the viewpoint of ink ejection properties, the average primary particle size of the white pigment is preferably 400 nm or less, more preferably 350 nm or less.

[0246] In the present invention, the average primary particle size of the white pigment is a value measured using a transmission electron microscope (TEM). Specifically, it is a value obtained by selecting any 50 white pigments present in the viewing angle observed by TEM, measuring the primary particle sizes of 50 particles, and averaging them. As a transmission electron microscope, a transmission electron microscope 1200EX manufactured by JEOL Ltd. can be used.

[0247] Furthermore, the pigment may be a water-insoluble pigment that can be dispersed in water using a dispersant, or may be a self-dispersible pigment.

[0248] The self-dispersible pigment is a pigment that can be dispersed in water without using a dispersant.

[0249] The self-dispersible pigment refers to a compound in which at least one selected from the group consisting of hydrophilic groups such as carbonyl, hydroxyl, carboxyl, sulfonyl, and phosphoric acid groups and salts thereof is chemically bonded to the surface of the pigment directly or via other groups.

[0250] When the first ink contains a white pigment, the content of the white pigment is preferably 2% to 25% by mass, more preferably 5% to 25% by mass, and even more preferably 10% to 20% by mass relative to the total amount of the first ink from the viewpoint of image density and ejection properties.

[0251] When the first ink contains a pigment other than the white pigment, the content of the 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, relative to the total amount of the first ink, from the viewpoint of image density and ejection properties.

[0252] -Resin-

[0253] The first ink preferably contains at least one type of resin.

[0254] The resin in the first ink contributes to the film-forming property of the ink (ie, the formability of the ink film).

[0255] The weight average molecular weight (Mw) of the resin is preferably 1,000 to 300,000, more preferably 2,000 to 200,000, and further preferably 5,000 to 100,000.

[0256] As the resin, there can be mentioned a pigment dispersion resin which is a pigment dispersant.

[0257] Examples of the resin include resin particles.

[0258] When the first ink contains a pigment as a colorant, the first ink preferably contains at least one pigment dispersion resin.

[0259] The pigment dispersion resin is a resin having a function of dispersing a pigment.

[0260] The pigment dispersing resin may be a random copolymer or a block copolymer.

[0261] The pigment dispersion resin may have a cross-linked structure.

[0262] The first ink can be prepared using a pigment dispersion containing a pigment and a pigment dispersion resin.

[0263] As the pigment dispersion resin, for example, a known polymer dispersant such as the polymer dispersants described in paragraphs 0029 to 0106 of International Publication No. 2021 / 221069 can be used.

[0264] When the first ink contains a pigment dispersion resin, the ratio of the content of the pigment in the first ink to the content of the pigment dispersion resin is preferably 1:0.04 to 1:3, more preferably 1:0.05 to 1:1, and further preferably 1:0.05 to 1:0.5 on a mass basis.

[0265] When the first ink contains a pigment dispersion resin, the content of the pigment dispersion resin is preferably 0.1 to 10% by mass, more preferably 0.3 to 5% by mass, and even more preferably 0.5 to 2.5% by mass, based on the total amount of the first ink.

[0266] From the viewpoint of anti-blocking property, the first ink preferably contains at least one kind of resin particles. Examples of the resin particles that may be contained in the first ink include the same resin particles that may be contained in the pretreatment liquid.

[0267] The content of the resin particles is preferably 1% by mass to 20% by mass, more preferably 2% by mass to 15% by mass, and even more preferably 2% by mass to 10% by mass, relative to the total amount of the first ink.

[0268] -Water-soluble organic solvents-

[0269] The first ink preferably contains at least one water-soluble organic solvent.

[0270] This can further ensure the discharge stability from the inkjet head.

[0271] Examples of the water-soluble organic solvent in the first ink include the same water-soluble organic solvents as those that may be contained in the pretreatment liquid.

[0272] The content of the water-soluble organic solvent is preferably 10% by mass to 40% by mass, and more preferably 15% by mass to 30% by mass, relative to the total amount of the first ink.

[0273] -additive-

[0274] The first 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 required.

[0275] -Physical properties-

[0276] From the viewpoint of improving ejection stability, the pH (25° C.) of the first ink is preferably 7 to 10, and more preferably 7.5 to 9.5. The pH of the first ink can be measured by the same method as the pH of the pretreatment liquid.

[0277] The viscosity (25° C.) of the first 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 further preferably 3 mPa·s to 10 mPa·s.

[0278] The viscosity of the first ink can be measured by the same method as the viscosity of the pretreatment liquid.

[0279] The surface tension (25° C.) of the ink is preferably 60 mN / m or less, more preferably 20 mN / m to 50 mN / m, and even more preferably 25 mN / m to 40 mN / m.

[0280] The surface tension of the first ink can be measured by the same method as the surface tension of the pretreatment liquid.

[0281] (Method of applying ink)

[0282] The first ink is applied by an inkjet recording method.

[0283] There is no particular limitation on the ink ejection method in the inkjet recording method, and it may be a known method, for example, a charge control method that utilizes electrostatic induction force to eject ink, a drop-on-demand inkjet method (pressure pulse method) that utilizes the vibration pressure of a piezoelectric element, an acoustic inkjet method that converts an electrical signal into a sound beam and irradiates the beam onto the ink to eject the ink using radiation pressure, and a thermal inkjet (Bubble Jet (registered trademark)) method that heats the ink to form bubbles and utilizes the generated pressure.

[0284] As the inkjet recording method, in particular, the inkjet recording method described in Japanese Patent Publication No. 54-59936 can be effectively used, in which the ink subjected to thermal energy undergoes a rapid volume change, and the ink is ejected from the nozzle by the force generated by the state change. As the inkjet recording method, the method described in paragraphs 0093 to 0105 of Japanese Patent Publication No. 2003-306623 can also be applied.

[0285] Inkjet recording is performed by applying ink to a non-permeable substrate by ejecting the ink from the nozzles of an inkjet head.

[0286] As inkjet head methods, there are a shuttle method and a linear method. In the shuttle method, a short serial head records while scanning along the width direction of a non-permeable substrate; in the linear method, a line head is used in which recording elements are arranged in the entire area corresponding to one side of the non-permeable substrate.

[0287] In the linear method, the image can be recorded on the entire surface of the impermeable substrate by scanning the impermeable substrate in a direction intersecting the arrangement direction of the recording elements. In the linear method, a transport system such as a carriage for scanning a short strip of inkjet head in the reciprocating method is not required. In addition, in the linear method, compared with the reciprocating method, the movement of the carriage and the complicated scanning control of the recorded medium are not required, and only the impermeable substrate is moved. Therefore, according to the linear method, compared with the reciprocating method, it is possible to achieve high-speed image recording.

[0288] The first ink is preferably applied using an inkjet head having a resolution of 300 dpi or more (more preferably 600 dpi or more, and even more preferably 800 dpi or more). Dpi is an abbreviation for dot per inch, and 1 inch is 2.54 cm.

[0289] From the viewpoint of obtaining a high-definition image, the ejection amount of the first ink is preferably 1 pL (picoliter) to 10 pL, and more preferably 1.5 pL to 6 pL.

[0290] <First ink drying process>

[0291] In the first ink drying step, the first ink is dried under the drying conditions of wind speed V m / sec, drying temperature T° C., and drying time t sec.

[0292] The wind speed is preferably higher than 0 m / s, that is, the drying method of the first ink is preferably air drying. The air supply to the first ink can be performed using, for example, an air blower. The air blown from the air blower can be cold air or warm air.

[0293] Preferred aspects of the wind speed, drying temperature, and drying time in the first ink drying step are as described above.

[0294] <Second ink application step>

[0295] In the second ink applying step, a second ink containing water and a colorant is applied to the non-permeable substrate to which the pre-treatment liquid and the first ink have been applied.

[0296] Preferred aspects of the components contained in the second ink are the same as preferred aspects of the components contained in the first ink.

[0297] The method of applying the second ink is the same as the method of applying the first ink.

[0298] The inkjet recording method of the present invention may include other steps in addition to the pretreatment liquid applying step, the pretreatment drying step, the first ink applying step, the first ink drying step, and the second ink applying step.

[0299] The inkjet recording method of the present invention preferably includes a step of drying the second ink after the second ink application step. The method for drying the second ink is not particularly limited, but is preferably performed under the same conditions as the first ink.

[0300] Example

[0301] Hereinafter, the present invention will be specifically described by way of examples, but the present invention is not limited to the following examples.

[0302] <Preparation of pretreatment solution>

[0303] The components shown in Table 1 were mixed to prepare a pretreatment liquid.

[0304] The details of the components shown in Table 1 are as follows: The contents of resins 1 to 3 in Table 1 refer to the contents of the resins as solid contents in the aqueous dispersion of the product.

[0305] Glutaric acid

[0306] ·Calcium acetate: Calcium acetate

[0307] Resin 1: Aqueous dispersion of acrylic resin (product name: "Mowinyl 6770", manufactured by Japan Coating Resin Co., Ltd.)

[0308] Resin 2: Aqueous dispersion of styrene acrylic resin (product name: "HIROS QE-1042", manufactured by SEIKO PMC CORPORATION)

[0309] Resin 3: Aqueous dispersion of polyurethane resin (product name "SUPERFLEX 500M", manufactured by DKS Co. Ltd.)

[0310] PGmME: Propylene glycol monomethyl ether

[0311] Defoamer: Product name "BYK-024", manufactured by BYK

[0312] ·Dimethylaminoethanol

[0313] · Silicone surfactant: Product name "BYK-347", manufactured by BYK

[0314] [Table 1]

[0315] Pretreatment solution 1 Pretreatment liquid 2 Pretreatment solution 3 Pretreatment liquid 4 Pretreatment liquid 5 Pretreatment liquid 6 Pretreatment liquid 7 Pretreatment liquid 8 Glutaric acid 10 10 5 2 10 10 10 - Calcium acetate - - - - - - - 10 Resin 1 10 5 10 10 2 - - 10 Resin 2 - - - - - 10 - - Resin 3 - - - - - - 10 - PGmME 5 5 5 5 5 5 5 5 Defoaming agent 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 Dimethylaminoethanol 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 Silicone surfactants 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 water 74.79 79.79 79.79 82.79 82.79 74.79 74.79 74.79 total 100 100 100 100 100 100 100 100

[0316] <Preparation of the first ink and the second ink>

[0317] The first ink was prepared by mixing the components shown in Table 2.

[0318] The second ink was prepared by preparing the white pigment dispersion 1 in advance and then mixing the white pigment dispersion 1 with other components (components other than the white pigment and the pigment dispersion resin 1 shown in Table 2).

[0319] The details of the components shown in Table 2 are as follows: The content of the resin 4 in Table 2 refers to the content of the resin as a solid content in the aqueous dispersion of the product.

[0320] The description of the same components as those contained in the pretreatment liquid will be omitted.

[0321] Black pigment dispersion: Product name "Projet Black APD4000", manufactured by FUJIFILM Imaging Colorants Inc., Pigment concentration: 15 mass%

[0322] · White pigment: titanium dioxide pigment (product name "PF-690", manufactured by ISHIHARA SANGYO KAISHA, LTD., average primary particle size: 210 nm)

[0323] Pigment dispersion resin 1: a resin synthesized by the method described later.

[0324] PG: 1,2-propylene glycol

[0325] · Acetylene glycol surfactant: product name "OLFINE E1010", manufactured by Nissin Chemical Co., Ltd. · Silica particles: colloidal silica (product name "SNOWTEX XS", manufactured by Nissan Chemical Corporation)

[0326] Resin 4: Aqueous dispersion of polyurethane resin (product name: "PERMARIN UA-200", manufactured by SANYO CHEMICAL INDUSTRIES, LTD.)

[0327] (Synthesis of Pigment Dispersing Resin 1)

[0328] 100 g of dipropylene glycol was added to a three-necked flask equipped with a stirrer and a cooling tube, and the mixture was heated to 85° C. under a nitrogen atmosphere.

[0329] The following solution 1 and solution 2 were prepared respectively. Solution 1 was prepared by mixing 14.0 g of stearyl methacrylate, 35.3 g of benzyl methacrylate, 20.0 g of hydroxyethyl methacrylate, 30.7 g of methacrylic acid and 0.55 g of 2-mercaptopropionic acid; and solution 2 was prepared by dissolving 1.0 g of tert-butyl peroxy-2-ethylhexanoate (product name "PERBUTYL O", manufactured by NOF CORPORATION) in 20 g of dipropylene glycol.

[0330] Solution 1 was added dropwise to the three-necked flask over 4 hours, and solution 2 was added dropwise over 5 hours.

[0331] After the addition was completed, the mixture was allowed to react for a further 2 hours, and then the temperature was raised to 95°C and heated and stirred for 3 hours to allow all unreacted monomers to react. 1 H-NMR) method confirmed the disappearance of the monomer.

[0332] The obtained reaction solution was heated to 70° C., and after adding 12.0 g of dimethylethanolamine, propylene glycol was added and stirred to obtain a 30 mass % solution of the pigment dispersion resin 1.

[0333] pass 1 H-NMR confirmed the structural unit of the obtained pigment dispersion resin 1. In addition, the weight average molecular weight (Mw) determined by GPC was 28,000.

[0334] The mass ratio of each structural unit in the pigment dispersion resin 1 is structural unit derived from stearyl methacrylate / structural unit derived from benzyl methacrylate / structural unit derived from hydroxyethyl methacrylate / structural unit derived from methacrylic acid = 14 / 35.3 / 20 / 30.7. However, the above mass ratio is a value excluding dimethylaminoethanol.

[0335] The acid value of the pigment dispersion resin 1 was 200 mgKOH / g.

[0336] (Preparation of White Pigment Dispersion Liquid 1)

[0337] Pigment dispersion 1 was prepared using Ready mill model LSG-4U-08 (manufactured by AIMEX. CO., Ltd.).

[0338] 45 parts by mass of titanium dioxide pigment (average primary particle size: 210 nm, trade name "PF-690", manufactured by ISHIHARA SANGYO KAISHA, LTD.) as a white pigment, 15 parts by mass of a 30% solution of the above-mentioned pigment dispersion resin 1, and 40 parts by mass of ultrapure water were added to a zirconia container. Furthermore, 40 parts by mass of 0.5 mm φ zirconia beads (manufactured by TORAYINDUSTRIES, INC., TORAYCERAM beads) were added and gently mixed with a spatula. The zirconia container containing the obtained mixture was placed in a Ready mill and dispersed for 5 hours at a speed of 1000 rpm (revolutions per minute). After the dispersion was completed, the beads were removed by filtering with a filter cloth to obtain a white pigment dispersion 1 having a concentration of 45% by mass of white pigment.

[0339] [Table 2]

[0340] No. 1 ink Second ink Black pigment dispersion 6 - White pigment - 15 Pigment dispersion resin 1 - 1.5 PG 20 15 PGmME 2 5 Acetylene glycol surfactant 0.5 0.5 Silicone surfactants 0.5 0.5 Silica particles 0.05 0.05 Resin 4 4 4 water 67.0 58.5 total 100 100

[0341] <Image Record>

[0342] An inkjet recording device is prepared, which includes: a conveying system for continuously conveying a long strip of substrate; a flexographic printing machine for applying a pretreatment liquid to the substrate; a warm air dryer for drying the pretreatment liquid; a first inkjet head for applying a first ink; a first warm air dryer for drying the first ink; a second inkjet head for applying a second ink; and a second warm air dryer for drying the second ink.

[0343] Furthermore, as a substrate, a polyethylene terephthalate (PET) substrate ("FE2001" manufactured by FUTAMURA CHEMICAL CO., LTD.) (thickness 12 μm, width 780 mm, length 4000 m; hereinafter referred to as "impermeable substrate A") was prepared as an impermeable substrate.

[0344] While the impermeable substrate A was continuously conveyed at 50 m / min using an inkjet recording device, the pretreatment liquid was applied to the impermeable substrate A by a flexographic printing press so that the amount of coagulant applied reached the value described in Table 3 (pretreatment liquid application step). Next, the pretreatment liquid was applied to the impermeable substrate A under the drying conditions described in Table 3 (wind speed V p , Drying temperature T p , Drying time t p ) and dried the pretreatment liquid (pretreatment liquid drying step).

[0345] The first ink was ejected from the first inkjet head and applied to the surface of the non-permeable substrate A coated with the pretreatment liquid in the form of a solid image (first ink applying step). The applied first ink was dried under the drying conditions (wind speed V, drying temperature T, drying time t) described in Table 3 (first ink drying step). Furthermore, the second ink was ejected from the inkjet head and applied to the first ink in the form of a solid image (second ink applying step). The applied second ink was dried for 5 seconds at a drying temperature of 80° C. and a wind speed of 10 m / s to obtain an image record (second ink drying step).

[0346] In the above-mentioned image recording, the continuous ejection property of the second ink was evaluated. Furthermore, the anti-blocking property and image quality of the obtained image recording material were evaluated by the following method.

[0347] [Continuous discharge]

[0348] The above image recording was performed for 10 minutes (equivalent to a length of 500 meters of the non-permeable substrate A), and the number of streaks T0 in the solid image at the start of the ejection of the second ink and the number of streaks T1 in the solid image when ejected 10 minutes later were visually observed. The continuous ejection property was evaluated based on the increase in the number T1 relative to the number T0. The evaluation method is as follows.

[0349] 5: Increase the number of items from 0 to 5.

[0350] 4: Increase the number to 6 to 10.

[0351] 3: The number of additional items is 11 to 20.

[0352] 2: The number of additional items is 21 to 30.

[0353] 1: The number of additional items is 31 or more.

[0354] [Anti-blocking properties]

[0355] After the above image recording, the impermeable substrate A was wound up using a winding device. It was placed for 1 day in the wound state. After 1 day, it was unwound using an unwinding device. Visually confirm whether there is adhesion on the back side of the impermeable substrate A. Specifically, adhesion refers to the phenomenon that the substrates are adhered to each other. On the image recording surface of the impermeable substrate A with a width of 70 cm and a length of 70 cm, the area where adhesion was confirmed was calculated. The evaluation criteria are as follows.

[0356] 5: No adhesion was confirmed.

[0357] 4: Blocking was observed in an area of ​​5% or less of the image recording surface.

[0358] 3: Blocking was observed in an area of ​​more than 5% and less than 20% of the image recording surface.

[0359] 2: Blocking was observed in an area of ​​more than 20% and less than 40% of the image recording surface.

[0360] 1: Blocking was observed in more than 40% of the area of ​​the image recording surface.

[0361] [Image Quality]

[0362] The same method as the above-mentioned image recording was used to obtain an image recording material having a character image recorded on the non-permeable substrate A. As the character image, 4pt, 6pt, 8pt and 10pt were printed. Figure 1 The characters shown are (Unicode: U+9DF9). Here, pt refers to the DTP point indicating the font size, and 1pt is 1 / 72 inch.

[0363] The image quality (character quality) was evaluated by observing each character image on the image record and judging whether it could be reproduced. “Reproducible” means that when checked from a distance of 0.5 m, Figure 1 In the character image shown, Figure 1 The horizontal line marked 11 in Figure 1 The horizontal line indicating 12 in the middle is separated. The evaluation criteria are as follows.

[0364] 5: Capable of reproducing 4pt characters.

[0365] 4: Able to reproduce 6pt characters, but unable to reproduce 4pt characters.

[0366] 3: Can reproduce 8pt characters, but cannot reproduce characters below 6pt.

[0367] 2: Can reproduce 10pt characters, but cannot reproduce characters below 8pt.

[0368] 1: 10pt characters cannot be reproduced.

[0369] The evaluation results are shown in Table 3. In Table 3, "Formula (1)" refers to the calculation formula "50V+TtM / P" related to Formula (1). "Formula (3)" refers to the calculation formula "20V p +50V+(Tt+T p t p )M / P". "Formula (4)" refers to the calculation formula "(50V+TtM / P) / S" related to formula (4). "Formula (5)" refers to the calculation formula "(T-Tg)t" related to formula (4).

[0370] [Table 3]

[0371]

[0372] As shown in Table 3, in Examples 1 to 33, since V, T, t, M, and P satisfy the equations (1) and (2), it is found that an image having excellent continuous ink ejection properties and excellent anti-blocking properties can be recorded.

[0373] On the other hand, in Comparative Examples 1 to 3 and Comparative Example 5, since V, T, t, M, and P do not satisfy Formula (1), it can be seen that the continuous ejection property of the ink is poor. In addition, in Comparative Examples 4 and Comparative Examples 6, since V, T, t, M, and P do not satisfy Formula (1), it can be seen that the anti-blocking property of the image is poor.

[0374] In Example 2, since V, T, t, M, and P satisfy the formula (1A), it can be seen that the continuous ejection property of the ink is superior to that of Example 10. In addition, in Example 3, since V, T, t, M, and P satisfy the formula (1A), it can be seen that the anti-blocking property of the image is superior to that of Example 1.

[0375] In Example 2, due to V, T, t, M, P, V p 、T p and t p Since formula (3) is satisfied, it can be seen that the continuous ejection property of the ink is superior to that of Example 6 and Example 16. p 、T p and t p Since the formula (3) is satisfied, it can be seen that the anti-blocking property of the image is excellent compared with that of Example 3, Example 12, Example 13, Example 23, and Example 32.

[0376] In Example 2, since V, T, t, M, P, and S satisfy the formula (4), it can be seen that the continuous ejection property of the ink is excellent compared with Example 18. In addition, in Example 4, since V, T, t, M, P, and S satisfy the formula (4), it can be seen that the anti-blocking property of the image is excellent compared with Example 17.

[0377] In Example 2, the amount of coagulant applied to the impermeable substrate was 0.03 g / m 2 As described above, it can be seen that the image quality is superior to that of Example 19. In Example 2, the amount of the coagulant applied to the non-permeable substrate is 0.15 g / m 2 It is found that the anti-blocking property of the image is excellent compared with Example 20.

[0378] In Example 2, since T, t and Tg satisfy the formula (5), it can be seen that the continuous ejection property of the ink is superior to that of Example 21. In addition, in Example 7, since T, t and Tg satisfy the formula (5), it can be seen that the anti-blocking property of the image is superior to that of Example 22.

[0379] In addition, the disclosure of Japanese Patent Application No. 2022-148465 filed on September 16, 2022 is incorporated by reference in its entirety into this specification. Furthermore, all documents, patent applications, and technical specifications described in this specification are incorporated by reference into this specification to the same extent as if each document, patent application, and technical specification incorporated by reference was specifically and individually described.

Claims

1. An inkjet recording method comprising the following steps: A step of applying a pretreatment liquid containing water, a coagulant with a molecular weight of 1000 or less, and a resin to an impermeable substrate; The step of drying the pretreatment liquid; A step of applying a first ink containing water and a colorant to the non-permeable substrate to which the pretreatment liquid has been applied by an inkjet recording method; A step of drying the first ink under drying conditions of wind speed V m / s, drying temperature T°C, and drying time t seconds; and The step of applying a second ink containing water and a colorant to the non-permeable substrate to which the pre-treatment liquid and the first ink have been applied by an inkjet recording method, When the content of the coagulant relative to the total amount of the pretreatment liquid is M mass %, and the content of the resin relative to the total amount of the pretreatment liquid is P mass %, V, T, t, M and P satisfy the following formulas (1) and (2): 3500≥50V+TtM / P≥700 (1), 120≥T≥25 (2)。 2. The inkjet recording method according to claim 1, wherein The V, the T, the t, the M, and the P satisfy the following formula (1A), 3000≥50V+TtM / P≥1000(1A).

3. The inkjet recording method according to claim 1 or 2, wherein: In the process of drying the pre-treated liquid, at a wind speed V p m / s, drying temperature T p ℃, drying time t p drying the pretreatment liquid under the drying conditions of 100 s, The V, the T, the t, the M, the P, the V p , the T p And the said p Satisfies the following formula (3), 3500≥20V p +50V+(Tt+T p t p )M / P≥1500 (3)。 4. The inkjet recording method according to claim 1 or 2, wherein: When the tension of the impermeable substrate is set to S, V, T, t, M, P and S satisfy the following formula (4), where the unit of S is N / m: 50≥(50V+TtM / P) / S≥15 (4).

5. The inkjet recording method according to claim 1 or 2, wherein: The amount of the coagulant applied to the impermeable substrate was 0.03 g / m 2 ~0.15g / m 2 .

6. The inkjet recording method according to claim 1 or 2, wherein: When the glass transition temperature of the resin contained in the pretreatment liquid is Tg°C, the T, t and Tg satisfy the following formula (5): 1500≥(T-Tg)t≥200 (5).

Images