Method for forming a solute film pattern

Abstract

The present application provides a solute film pattern forming method that improves ejection stability and film quality. The solute film pattern forming method includes: a coating step S1 in which a material liquid is coated on a medium by an inkjet method, the material liquid including water, a humectant having a boiling point of 180°C or higher, a solute, and an additive, the content of the humectant being 10% or more and 30% or less by mass with respect to the total amount; a first pressure reduction step S2 in which the atmosphere of the material liquid coated on the medium is reduced to 3000 Pa, which is the vapor pressure of water at room temperature; and a second pressure reduction step S3 in which the atmosphere is reduced to a pressure below the vapor pressure of the humectant at room temperature, and the pressure is maintained for a certain time or more, and as the humectant, one or more of gamma-butyrolactone, propylene carbonate, ethylene glycol, propylene glycol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, dipropylene glycol, and 1,2-pentanediol are included.

Description

Technical Field

[0001] This invention relates to a method for forming a solute film pattern. Background Technology

[0002] It has long been known that methods exist for applying liquids to a medium using inkjet printing, thereby forming film patterns from the solutes in the liquid. For example, Patent Document 1 discloses an image forming method for forming film patterns such as images on fabric. Furthermore, Patent Document 2 discloses a method for manufacturing a color filter, in which ink is applied to an ink receiving layer and openings using inkjet printing to form patterned colored portions.

[0003] Patent Document 1: Japanese Patent Application Publication No. 2003-220701

[0004] Patent Document 2: Japanese Patent Application Publication No. 2002-182028

[0005] However, the methods described in Patent Documents 1 and 2 suffer from technical problems that make it difficult to improve the ejection stability of the inkjet head and the film quality of the formed film pattern. Specifically, in inkjet printing, to stably eject liquids such as ink, a high-boiling-point solvent is sometimes added to the ink to control the drying of the ink within the nozzle. On the other hand, high-boiling-point solvents are difficult to volatilize and may remain in the formed film pattern, potentially reducing film quality such as adhesion to the substrate. Furthermore, excessively promoting the volatilization of high-boiling-point solvents may cause the ink to boil violently during the drying process, impairing film quality such as smoothness. Therefore, a method for forming solute film patterns that improves ejection stability and film quality is needed. Summary of the Invention

[0006] The method for forming a solute film pattern includes the following steps: coating a liquid onto a medium using an inkjet printer; the liquid comprising water, a humectant with a boiling point of 180°C or higher, a solute, and an additive; wherein the content of the humectant is 10% by mass or more and 30% by mass or less relative to the total amount; depressurizing the atmosphere of the liquid coated onto the medium to the vapor pressure of water at room temperature, i.e., 3000 Pa; and depressurizing the atmosphere to a pressure below the vapor pressure of the humectant at room temperature, and maintaining the pressure for a certain period of time or more; wherein the humectant comprises one or more of γ-butyrolactone, propylene carbonate, ethylene glycol, propylene glycol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, dipropylene glycol, and 1,2-pentanediol. Attached Figure Description

[0007] Figure 1 This is a flowchart illustrating the method for forming a solute film pattern in this embodiment.

[0008] Figure 2This is a table showing the composition and evaluation results of the material liquids in the embodiments and comparative examples.

[0009] Figure 3 This is a table showing the set pressure and evaluation results in the second decompression process of the embodiments and comparative examples.

[0010] Figure 4 This is a table showing the composition and evaluation results of the material liquids in the embodiments and comparative examples.

[0011] Figure 5 This is a table showing the composition and evaluation results of the material liquids in the embodiments and comparative examples.

[0012] Figure 6 This is a table showing the composition and evaluation results of the material liquids in the embodiments and comparative examples. Detailed Implementation

[0013] like Figure 1 As shown, the solute film pattern formation method in this embodiment includes a coating step S1 of coating liquid, a first decompression step S2 of performing a first decompression, and a second decompression step S3 of performing a second decompression. The solute film pattern formation method of this embodiment described below is an example, but is not limited thereto.

[0014] As a preliminary stage of coating process S1, a liquid material serving as a solute film pattern is prepared. This liquid contains water, a humectant, a solute, and additives. In the following description, the liquid material serving as the solute film pattern will also be referred to as the material liquid. A solute film pattern refers to a functional film formed into a predetermined shape. Examples of functional films include conductive films, insulating films, protective films, and optical films.

[0015] Water is the primary solvent of the material liquid. That is, the material liquid is aqueous. Water is the component that evaporates after the material liquid adheres to the medium described later. The water used can be pure water or ultrapure water, such as ion-exchanged water, ultrafiltration water, reverse osmosis water, or distilled water, after removing as many ionic impurities as possible. Furthermore, using water sterilized by ultraviolet irradiation or the addition of hydrogen peroxide can inhibit the growth of mold and bacteria during long-term storage of the material liquid. The water content in the material liquid is appropriately adjusted according to the type of solute film pattern formed by the material liquid, the material of the medium, and the characteristics of the inkjet head used in the coating process S1.

[0016] The humectant is an organic solvent with a boiling point above 180°C, which inhibits the drying of the liquid material within the inkjet head nozzle. This improves ejection stability when the liquid material is ejected from the inkjet head during coating step S1. Furthermore, it prevents nozzle clogging when the inkjet head is not used for extended periods. It should be noted that in this specification, boiling point refers to the standard boiling point. Additionally, the room temperature in this specification is approximately 20°C to 25°C.

[0017] Specifically, the humectants are γ-butyrolactone (204℃, 150.0 Pa), propylene carbonate (242℃, 11.3 Pa), ethylene glycol (198℃, 7.0 Pa), propylene glycol (187℃, 10.7 Pa), 1,3-propanediol (214℃, 4.5 Pa), 1,2-butanediol (193℃, 10.0 Pa), 1,3-butanediol (207℃, 8.0 Pa), dipropylene glycol (231℃, 4.0 Pa), and 1,2-pentanediol (206℃, 1.5 Pa). The values ​​in parentheses following the names of the above organic solvents are their boiling points (℃) and vapor pressures (Pa) at room temperature. The material liquid contains one or more of the above organic solvents as humectants.

[0018] The aforementioned organic solvents, with boiling points above 180°C, are effective in suppressing the drying of the material liquid within the nozzle. Furthermore, these organic solvents have high water solubility, thus reducing the likelihood of defects such as humectant separation in the material liquid.

[0019] In existing liquid materials such as inks, high-boiling-point compounds such as glycerin and 1,5-pentanediol are sometimes used as moisturizing ingredients. These high-boiling-point compounds have lower vapor pressures than the aforementioned organic solvents, and therefore tend to be difficult to volatilize and easily remain in functional films. In contrast, the aforementioned organic solvents, with boiling points above 180°C, are suitable as moisturizers and are more easily volatilized than the high-boiling-point compounds.

[0020] The content of the humectant in the liquid material is 10% by mass or more and 30% by mass or less relative to the total amount of the liquid material, preferably 10% by mass or more and 20% by mass or less. This suppresses the drying of the liquid material within the nozzle and also inhibits residue formation in the solute film pattern, thereby improving the film quality of the solute film pattern. Furthermore, it can suppress the increase in viscosity of the liquid material caused by the aforementioned organic solvents.

[0021] The solute is the component responsible for the function and properties of the solute film pattern. There are no particular limitations on the solute; examples include particles such as carbon black and silica, solvent-based resins such as polyvinyl alcohol, and resin emulsions such as polyurethane. The resin is used, for example, as a binder to fix particles such as carbon black within the solute film pattern. This allows the formation of a solute film pattern containing particles. The solute content in the material liquid is appropriately adjusted according to the type and application of the solute film pattern formed by the material liquid, and the characteristics of the inkjet head. For example, from the viewpoint of allowing the particles in the solute film pattern to exhibit their original properties, it is preferable that the resin in the solute film pattern is in a small amount.

[0022] Additives are formulated to improve the properties of liquid materials and the characteristics of solute film patterns. Examples of additives include surfactants, pH adjusters, and chelating agents.

[0023] Surfactants reduce the surface tension of liquid materials, improving the ejection characteristics of the liquid material ejected from the inkjet head and the wettability of the liquid material to the medium. Examples of surfactants include acetylenic glycol surfactants, silicone surfactants, and fluorinated surfactants. Commercially available surfactants can be used.

[0024] When the material liquid contains a surfactant, the content is not particularly limited, but it is preferably 0.01% by mass or more and 2.00% by mass or less relative to the total amount of the material liquid.

[0025] pH adjusters raise the pH of the liquid material, inhibiting the deterioration of components such as the inkjet head. Examples of pH adjusters include inorganic bases and organic amine compounds. Well-known compounds can also be used. When a pH adjuster is included in the liquid material, its concentration is adjusted appropriately based on the pH of the liquid material before the addition of the pH adjuster.

[0026] Chelating agents use their chelating effect to complex metal ions mixed in the liquid material, inhibiting the precipitation of metal salts. This prevents defects such as clogging in the inkjet nozzles.

[0027] Examples of chelating agents include ethylenediaminetetraacetic acid (EDTA), sodium pyridinecarboxylate, potassium quinolineate, tetrasodium 3-hydroxy-2,2'-iminodisuccinate, methylglycine diacetic acid (MGDA), L-glutamic acid diacetic acid (GLDA), L-aspartic acid diacetic acid (ASDA), hydroxyethyliminodisuccinate (HIDA), 3-hydroxy-2,2'-iminodisuccinic acid (HIDS), dicarboxymethylglutamic acid (CMGA), (S,S)-ethylenediaminedisuccinic acid (EDDS), and salts thereof. Examples of salts of the above chelating agents include metal salts such as sodium, potassium, and lithium, as well as salts of ammonium and amines.

[0028] When the liquid material contains a chelating agent, the content is not particularly limited, but it is preferably 0.01% by mass or more and 2.00% by mass or less relative to the total amount of the liquid material.

[0029] In addition to the additives mentioned above, the liquid material may also contain various additives such as preservatives, fungicides, and antioxidants. These additives can be made from known substances.

[0030] The material liquid may contain solvents other than water and humectants as other components, within a range that does not impair the membrane quality and solute pattern. These other solvents alter the drying properties of the material liquid by increasing the solute's solubility and by interacting with the humectant and water. Examples of such solvents include alkanediols, polyols, glycol ethers, and carbonates, in addition to the substances listed as humectants.

[0031] To prepare the liquid material, the above components are mixed in any order. Then, filtration or other methods are performed as needed to remove impurities and foreign matter. As a method for mixing the components, each component is added to a container equipped with a stirring device such as a mechanical stirrer, magnetic stirrer, or ultrasonic stirrer, and then stirred and mixed. As a filtration method, known methods such as centrifugal filtration or filter filtration can be used. Furthermore, a vacuum pump or similar device can be used to degas the liquid material.

[0032] Based on values ​​at 25°C, the surface tension of the material liquid is preferably 10 mN / m or more and 40 mN / m or less, more preferably 20 mN / m or more and 40 mN / m or less. This improves the ejection characteristics from the inkjet head. The surface tension of the material liquid can be measured using the Kyowa Interface Science CBVP-Z automated surface tension meter.

[0033] From the same perspective as surface tension, using values ​​at 20°C, the preferred viscosity of the liquid material is 2 mPa. s (mPa second) or higher and 15 mPa Below s, more preferably 2 mPa s or more and 5mPa Below s. The viscosity of a liquid material can be determined using a Pysica MCR-300 viscoelasticity tester. Specifically, the viscosity of a liquid material at 20°C is obtained by adjusting the temperature of the liquid material to 20°C, increasing the shear rate from 10 to 1000, and reading the viscosity at a shear rate of 200.

[0034] The properties and characteristic values ​​of the material liquid described above are just one example and are not limited to those described above.

[0035] In coating process S1, liquid material is coated onto a medium using inkjet printing. Inkjet printing refers to a method that uses changes in the volume of the liquid collection chamber within the inkjet head to eject droplets of liquid material from a nozzle. By using inkjet printing, relatively high-resolution solute film patterns can be formed. Furthermore, it facilitates the production of multiple varieties in small quantities.

[0036] Inkjet technology can be applied to known devices such as inkjet printers. Specifically, examples of inkjet printers include rack-mount or off-rack serial printers and line-head printers.

[0037] The inkjet head has an actuator that serves as a drive device. Examples of actuators include: piezoelectric elements that utilize the deformation of a piezoelectric body, electromechanical conversion elements that utilize the displacement of a vibrating plate caused by electrostatic adsorption, and electrothermal conversion elements that utilize bubbles generated by heating.

[0038] The medium on which the liquid material is coated is appropriately selected based on the intended use of the solute film pattern. Examples of media include: inorganic substrates such as quartz, silicon, and ceramics; films or plates such as polyvinyl chloride, polyethylene, polypropylene, and polyethylene terephthalate; plates made of metals or alloys such as iron, silver, copper, and aluminum; and fabrics made of natural or chemical fibers.

[0039] The coating process S1 can form any pattern on the surface of the medium by moving the inkjet head relative to the medium. Then, the process proceeds to the first decompression process S2.

[0040] In the first depressurization step S2, the atmosphere of the liquid material coated on the medium is reduced to the vapor pressure of water at room temperature, which is 3000 Pa. As a result, water is mainly removed from the liquid material.

[0041] Specifically, for example, the medium after the material liquid is coated in the coating process S1 is placed into a degassing tank equipped with a suction pump such as a vacuum pump. Then, the suction pump is started to gradually reduce the pressure in the degassing tank, that is, the pressure of the atmosphere mentioned above.

[0042] At this point, it is preferable to keep the valve opening of the pipe connecting the suction pump and the degassing tank relatively small, so that the pressure in the degassing tank decreases slowly. Water is a relatively volatile component in the liquid material. Therefore, by stabilizing the evaporation of this volatile component, water can be reliably removed while suppressing its boiling. By suppressing the boiling of solvents such as water, defects such as pinholes on the solute film pattern are suppressed, thereby improving film quality such as surface smoothness and internal uniformity. When the pressure in the degassing tank reaches 3000 Pa, the second depressurization step S3 begins.

[0043] In the second depressurization step S3, the pressure of the material liquid coated on the medium, i.e., the pressure in the degassing tank, is reduced to below the vapor pressure of the humectant at room temperature. Next, this pressure below the vapor pressure is maintained for a certain period of time or longer. This removes the humectant primarily from the material liquid. It should be noted that when the material liquid contains multiple humectants, the pressure below the vapor pressure refers to the vapor pressure of the humectant with the lowest vapor pressure at room temperature.

[0044] Specifically, in the first depressurization step S2, the medium is placed into the degassing tank, the suction pump is kept running, and the aforementioned valve is fully open to rapidly reduce the pressure inside the degassing tank. Since the humectant is less volatile than water, even with rapid depressurization at a pressure higher than the vapor pressure, it is less prone to violent boiling. Next, when the pressure inside the degassing tank is lower than the aforementioned vapor pressure, the depressurization state below the aforementioned vapor pressure is maintained.

[0045] By maintaining the aforementioned depressurized state for a certain period of time, the humectant can be reliably removed. This certain period of time is appropriately set based on the content and type of humectant in the material liquid, and the amount of material liquid coated onto the medium. Furthermore, this certain period of time can also be set by analyzing the residual components of the humectant in the formed solute film pattern. Examples of methods for analyzing residual components include, for instance, gas chromatography-mass spectrometry (GC-MS) for heating and removing gases from the solute film pattern.

[0046] Preferably, the total time for applying reduced pressure to the material liquid coated on the medium is set to 20 minutes or less. In the solute film pattern formation method of this embodiment, as described above, solvents such as water and humectants suppress the generation of boiling over and are easily removed. Therefore, even if the total time of the material liquid coated on the medium under reduced pressure is shortened to 20 minutes or less in the first reduced pressure step S2 and the second reduced pressure step S3, the film quality can be ensured. As a result, the time required to form the solute film pattern can be shortened.

[0047] Furthermore, it is preferable not to subject the liquid material coated on the medium to heating treatment at 30°C or higher. In the solute film pattern formation method of this embodiment, as described above, solvents such as water and humectants can be easily removed, and heating treatment can be omitted. As a result, in the solute film pattern, deterioration and changes in properties caused by thermal processes can be suppressed.

[0048] After the second depressurization process S3 is completed, atmospheric pressure is restored in the degassing tank through an atmospheric opening valve, etc. As a result, a solute film pattern is formed on the medium.

[0049] According to this embodiment, the following effects can be obtained.

[0050] This improves the ejection stability and film quality of the solute film pattern. Specifically, since the humectant content is 10% by mass or more, the drying of the material liquid inside the inkjet nozzle is suppressed during the coating process S1, thus improving ejection stability. Furthermore, since the humectant content is 30% by mass or less, the humectant is less likely to remain in the solute film pattern, improving the adhesion between the solute film pattern and the substrate, and thus improving film quality.

[0051] After the water evaporates in the first decompression step S2, the pressure is reduced to below the vapor pressure of the humectant in the second decompression step S3 and maintained for a certain period of time, thereby making the humectant more volatile. Furthermore, this process suppresses bumping in the liquid material during the drying process and improves film quality, such as the smoothness of the solute film pattern.

[0052] By using the aforementioned organic solvent as the humectant, the solubility of the humectant in water is improved, making it less prone to separation. Furthermore, since the vapor pressure of the aforementioned organic solvent is sufficiently low compared to the vapor pressure of water, the drying of the material liquid within the nozzle is further suppressed. In summary, a method for forming a solute film pattern that improves ejection stability and film quality can be provided.

[0053] The following examples and comparative examples illustrate the effects of this embodiment in more detail. Figure 2 and Figures 4 to 6 In the material liquid composition column, the "-" indicates that it does not contain [certain substances]. Furthermore, the values ​​in the composition columns for carbon black dispersion and silica dispersion described later are converted values ​​based on solid content.

[0054] according to Figure 2 The composition of Material Liquid 1 is shown below. The components are mixed and stirred. Material Liquid 1 contains 10.0% by mass of 1,3-propanediol as a humectant. Specifically, Aqua-Black (registered trademark) 162 from Tokai Carbon Co., Ltd. is used as the carbon black dispersion. Olefin E series surfactant from Nissin Chemical Industries Co., Ltd. is used as the alkynyl glycol surfactant. Polyvinyl alcohol from Kanto Chemical Co., Ltd. is used as the polyvinyl alcohol. Polyvinyl alcohol requires a certain amount of time to dissolve; therefore, a 10% by mass aqueous solution is prepared beforehand, and the specified amount is added in solution form. Each component is weighed and added to a glass beaker, and the mixture is ultrasonically treated at room temperature for approximately 5 minutes to ensure thorough mixing, thus preparing Material Liquid 1.

[0055] Furthermore, as a comparative example, material liquid 2 was prepared by omitting the humectant 1,3-propanediol from material liquid 1. Material liquid 2 is composed of material liquid 1 in which the 1,3-propanediol is replaced with pure water. Except for the difference in composition mentioned above, comparative example material liquid 2 was prepared in the same manner as material liquid 1.

[0056] Next, intermittent printing was performed to evaluate material liquid 1 and material liquid 2, serving as indicators of the inkjet head's ejection stability. Specifically, material liquid 1 was placed in an ink reservoir and then filled into the Seiko Epson inkjet head S800 via a tubing. Then, a pattern was printed through the inkjet head nozzles to check the pattern, and a nozzle check was performed to confirm that all nozzles were ejecting material liquid 1 normally.

[0057] Next, the placement time between performing the nozzle inspection and reprinting the nozzle inspection pattern was varied, and the ejection status of each nozzle was examined. The ejection stability was evaluated according to the following evaluation criteria.

[0058] Evaluation criteria

[0059] A: Even after being left for 3 minutes, all nozzles sprayed normally.

[0060] B: After 2 minutes of rest, all nozzles sprayed normally, but after 3 minutes of rest, poor spraying occurred.

[0061] C: After 1 minute, all nozzles sprayed normally, but after 2 minutes, poor spraying occurred.

[0062] D: Even if left for 1 minute, poor spraying will still occur.

[0063] For material liquid 2, similarly to material liquid 1, the placement time was changed, the spraying state of each nozzle was examined, and the spraying stability was evaluated according to the above evaluation criteria.

[0064] The results of intermittent printing evaluation show that material liquid 1, within the inkjet head nozzle, suppresses surface drying and improves ejection stability. In contrast, material liquid 2, used as a comparative example, tends to dry out within the nozzle, making it difficult to improve ejection stability.

[0065] like Figure 3 As shown, for material liquid 1, after changing the pressure in the degassing tank in the second depressurization step S3 and forming a solute film pattern, the film quality of the solute film pattern is evaluated. Specifically, firstly, as described above, material liquid 1 is filled into the inkjet head, and it is confirmed that all nozzles are ejecting normally. Then, as the coating step S1, double-layer printing of material liquid 1 is performed on the medium with a solid overlap of 90 mm square on a medium under the conditions of a resolution of 1200 × 1200 dpi (dots per inch) and a droplet volume of 10 pL (picoli). As the medium, a glass substrate and a polyethylene terephthalate film are used.

[0066] Next, as the first depressurization process S2, the printed media are placed into the depressurization drying chamber, and the chamber pressure is reduced from atmospheric pressure to 3000Pa in 5 minutes by a scroll pump.

[0067] Next, as the second decompression step S3, in Example 1-1, the pressure in the chamber is reduced from 3000 Pa to the vapor pressure of 1,3-propanediol at room temperature, i.e., 4.5 Pa, in 6 minutes. The target pressure to which the pressure is reduced from 3000 Pa in the second decompression step S3 is called the set pressure.

[0068] Then, after the chamber reaches the set pressure, the humectant is continuously removed for 6 minutes while the pressure is reduced to below 80% of the set pressure. The pressure inside the chamber is adjusted by adjusting the opening of the exhaust valve of the depressurization drying chamber. Then, the vortex pump is stopped, the exhaust valve is opened, and after the chamber returns to atmospheric pressure, each medium with the solute film pattern of Example 1-1 is removed. The thickness of the solute film pattern of Example 1-1 formed on each medium is approximately 0.9 μm. Furthermore, in Example 1-1, the total time for applying depressurization is approximately 17 minutes, which allows the solute film pattern to be formed in a relatively short time.

[0069] In Comparative Example 1-1, the process was the same as in Example 1-1, except that the set pressure was set to 8.0 Pa, and solute film patterns of Comparative Example 1-1 were formed on each medium in the same manner. In Comparative Example 1-2, the process was the same as in Example 1-1, except that the set pressure was set to 14.0 Pa, and solute film patterns of Comparative Example 1-2 were formed on each medium in the same manner. In Comparative Example 1-3, the process was the same as in Example 1-1, except that the set pressure was set to 65.0 Pa, and solute film patterns of Comparative Example 1-3 were formed on each medium in the same manner. The thickness of each solute film pattern in Comparative Examples 1-1, 1-2, and 1-3 was approximately 0.9 μm.

[0070] Next, as an indicator of membrane quality, the conductivity of the solute membrane pattern at each level was measured. The results showed that there was no difference in conductivity between the examples and the comparative examples.

[0071] Next, as an indicator of membrane quality, the adhesion was evaluated using the cross-cut test for each level of solute membrane pattern. Specifically, the evaluation was conducted according to JIS K 5600-5-6:1999 General Test Methods for Coatings – Mechanical Properties of Coatings – Adhesion (Cross-cut Test). The appearance of the cross-cut areas after peeling off the adhesive tape was observed and classified, and the adhesion was evaluated according to the following evaluation criteria. It should be noted that there were no differences in the evaluation results of adhesion due to differences in the medium among the levels of the examples and comparative examples.

[0072] Evaluation criteria

[0073] A: The test result is classified as 0 (the edges of the grid are smooth, and no grid has peeled off).

[0074] B: The test results are classified as category 1.

[0075] C: The test results are classified as category 2.

[0076] D: The test results are classified into 3 categories.

[0077] C: The test results are categorized into 4 types.

[0078] D: The test results are classified as 5 (not even 4, the degree of peeling is obvious).

[0079] The evaluation results of the seal performance showed that in Examples 1-1, the humectant was reliably removed, improving the seal performance. In contrast, in all comparative examples, humectant residue was observed, making it difficult to improve the seal performance.

[0080] like Figure 4 As shown, material liquids with varying types of humectants were prepared, and intermittent printing evaluations were performed to assess the adhesion of solute film patterns formed by each material liquid. First, material liquids at various levels were prepared.

[0081] Specifically, in the material liquid of Example 2-1, compared with the above-mentioned material liquid 1, the humectant was changed to 1,2-butanediol, the content was set to 15.0% by mass, and the content of pure water was reduced by 5.0% by mass. Otherwise, the material liquid of Example 2-1 was prepared in the same manner as material liquid 1.

[0082] In the material liquid of Example 2-2, the humectant was changed to ethylene glycol, compared to the material liquid of Example 2-1. Otherwise, the same procedure was followed to prepare the material liquid of Example 2-2.

[0083] In the material liquids of Examples 2-3, the humectant was changed to 1,3-butanediol, compared to the material liquid of Example 2-1. Otherwise, the material liquids of Examples 2-3 were prepared in the same manner.

[0084] In the material liquids of Examples 2-4, compared to the material liquid of Example 2-1, the humectant was changed to dipropylene glycol, and the content of dipropylene glycol was set to 12.0% by mass. In addition, the content of pure water was increased by 3.0% by mass. Otherwise, the material liquids of Examples 2-4 were prepared in the same manner as the material liquid of Example 2-1.

[0085] In the material liquids of Examples 2-5, compared to the material liquid of Example 2-1, the humectant was changed to 1,2-pentanediol, and the content of 1,2-pentanediol was set to 10.0% by mass. In addition, the content of pure water was increased by 5.0% by mass. Otherwise, the material liquids of Examples 2-5 were prepared in the same manner as the material liquid of Example 2-1.

[0086] In the material liquid of Comparative Example 2-1, the humectant was omitted and the content of pure water was increased by 15.0% by mass, compared to the material liquid of Example 2-1. Otherwise, the material liquid of Comparative Example 2-1 was prepared in the same manner as the material liquid of Example 2-1.

[0087] Next, intermittent printing evaluation was performed in the same manner as for liquid material 1, and the evaluation results were recorded. Figure 4 The results of intermittent printing evaluation showed that in the material liquids of Examples 2-1 to 2-5, the drying of the liquid surface inside the inkjet nozzle was suppressed, thus improving ejection stability. In contrast, it was found that in the material liquid of Comparative Example 2-1, the liquid surface inside the nozzle dried easily, making it difficult to improve ejection stability.

[0088] Next, solute film patterns at each level were formed in the same manner as in Example 1-1 above, and the adhesion was evaluated. The evaluation results were recorded in [the relevant documentation]. Figure 4 It should be noted that, at each level, the set pressure for forming the solute film pattern was the vapor pressure of the respective humectant at room temperature. Since the material liquid in Comparative Example 2-1 did not contain a humectant, the set pressure was set to 100 Pa. Furthermore, the thickness of the solute film pattern at each level was approximately 0.9 μm.

[0089] The results of the adhesion evaluation showed that in Examples 2-1 to 2-5, the humectant was reliably removed, improving the adhesion. Furthermore, it was found that Comparative Example 2-1, which originally did not contain a humectant, exhibited improved adhesion.

[0090] according to Figure 5 The composition of the material liquids at each level is shown. The components were mixed and stirred. The material liquid of Example 3-1 contained 18.0% by mass of propylene glycol as a humectant. Specifically, as a silica dispersion, Nissan Chemical's Snowtex (registered trademark) C type (particle size 5 nm) was used, with a content of 4.0% by mass. The content of polyvinyl alcohol was changed to 0.4% by mass compared to material liquid 1. As an organosilicon surfactant, Nissin Chemical's SILFACE (registered trademark) SAG503A was used. Subsequently, the amount of change in each content was adjusted by adjusting the amount of pure water. Otherwise, the material liquid of Example 3-1 was prepared in the same manner as material liquid 1 described above.

[0091] The material liquid of Example 3-2 differs from that of Example 3-1 in that two humectants are used. Specifically, the material liquid of Example 3-2 contains 20% by mass of propylene glycol and 10% by mass of γ-butyrolactone as humectants, and the content of pure water is reduced by 12% by mass compared to the material liquid of Example 3-1. Otherwise, the material liquid of Example 3-2 is prepared in the same manner as the material liquid of Example 3-1.

[0092] Even in the material liquid of Example 3-3, the difference from the material liquid of Example 3-1 is that two humectants are used. Specifically, the material liquid of Example 3-3 contains 15% by mass of propylene glycol and 5% by mass of propylene carbonate as humectants, and the content of pure water is reduced by 2% by mass compared to the material liquid of Example 3-1. Otherwise, the material liquid of Example 3-3 is prepared in the same manner as the material liquid of Example 3-1.

[0093] In the material liquid of Comparative Example 3-1, the humectant was omitted and the content of pure water was increased by 18.0% by mass, compared with the material liquid of Example 3-1. Otherwise, the material liquid of Comparative Example 3-1 was prepared in the same manner as the material liquid of Example 3-1.

[0094] Next, for each level of material liquid, intermittent printing evaluation was performed in the same manner as for material liquid 1 described above, and the evaluation results were recorded. Figure 5 The results of intermittent printing evaluation showed that in the material liquids of Examples 3-1, 3-2, and 3-3, the drying of the liquid surface inside the inkjet nozzle was suppressed, improving ejection stability. This demonstrates that a moisturizing effect can be achieved even when using different humectants. In contrast, in the material liquid of Comparative Example 3-1, the liquid surface inside the nozzle dried easily, making it difficult to improve ejection stability.

[0095] Next, solute film patterns were formed for each level of the material liquid, and the film quality was evaluated. Specifically, the set pressure was set to 10.7 Pa, and in the second decompression step S3, the decompression time from 3000 Pa to the set pressure was set to 5 minutes, and the state of decompression to 80% of the next set pressure was maintained for 5 minutes. Otherwise, solute film patterns for each level were formed in the same manner as in Example 1-1. It should be noted that although the material liquid in Comparative Example 3-1 did not contain a humectant, the above conditions were made consistent with those in Example 3-1. The thickness of the solute film patterns formed for each level was approximately 0.7 μm.

[0096] Next, the adhesion of each solute film pattern was evaluated in the same manner as in Examples 1-1, and the results were recorded in [the relevant documentation]. Figure 5The results of the seal evaluation showed that in Examples 3-1, 3-2, and 3-3, the humectant was reliably removed, improving the seal. Furthermore, it was also found that in Comparative Example 3-1, since it originally did not contain a humectant, the seal was improved.

[0097] according to Figure 6 The composition of the material liquid shown in the figure was prepared by mixing and stirring the components. In the material liquid of Example 4-1, the humectant was changed to propylene glycol, compared to the material liquid of Example 2-1. Otherwise, the material liquid of Example 4-1 was prepared by operating in the same manner as the material liquid of Example 2-1.

[0098] The material liquid of Comparative Example 4-1 had the same composition as the material liquid of Example 4-1. In the material liquid of Comparative Example 4-2, the content of propylene glycol was increased to 32% by mass, and the content of pure water was decreased by 17% by mass, compared to the material liquid of Example 4-1. Otherwise, the material liquid of Comparative Example 4-2 was prepared in the same manner as the material liquid of Example 4-1. In the material liquid of Comparative Example 4-3, glycerol was used instead of propylene glycol, the content of glycerol was set to 8% by mass, and the content of pure water was increased by 7% by mass, compared to the material liquid of Example 4-1. Otherwise, the material liquid of Comparative Example 4-3 was prepared in the same manner as the material liquid of Example 4-1.

[0099] Next, for each level of material liquid, intermittent printing evaluation was performed in the same manner as for material liquid 1 described above, and the evaluation results were recorded. Figure 6 The results of intermittent printing evaluation showed that in the material liquids of Examples 4-1 and Comparative Examples 4-1 and 4-3, the drying of the liquid surface within the inkjet nozzle was suppressed, improving ejection stability. In contrast, in the material liquid of Comparative Example 4-2, ejection was unstable from the initial stage, and the nozzle inspection pattern could not be printed. This is presumably because, by increasing propylene glycol to 32% by mass, the viscosity of the material liquid at room temperature increased to approximately 56 mPa. s.

[0100] Next, solute film patterns are formed for each level of material liquid, and the film quality is evaluated. Specifically, in Example 4-1, compared to Example 1-1, the set pressure is set to 10.7 Pa, and in the second decompression step S3, the decompression time from 3000 Pa to the set pressure is set to 5 minutes, and the state of decompression to 80% of the subsequent set pressure is maintained for 5 minutes. Otherwise, the solute film pattern of Example 4-1 is formed in the same manner as in Example 1-1.

[0101] In Comparative Example 4-1, compared to Example 4-1, the first depressurization step S2 was omitted, and the pressure in the depressurization drying chamber was reduced from atmospheric pressure to the set pressure of 10.7 Pa in one go over 6 minutes. Then, the pressure was reduced to 80% of the set pressure and maintained for 5 minutes. Otherwise, the solute film pattern of Comparative Example 4-1 was formed by operating in the same manner as in Example 4-1.

[0102] In Comparative Example 4-2, the formation of the solute film pattern was omitted because the ejection of the liquid material was unstable.

[0103] In Comparative Example 4-3, the set pressure was set to the vapor pressure of glycerol at room temperature, i.e., 0.01 Pa. In the first decompression step S2, the pressure was reduced from atmospheric pressure to 3000 Pa in 5 minutes. In the second decompression step S3, the pressure was reduced from 3000 Pa to 0.01 Pa in 15 minutes, and then the pressure was maintained at 80% of the set pressure for 8 minutes. In Comparative Example 4-3, the total time for the first decompression step S2 and the second decompression step S3, i.e., the total time for applying the decompression, was 28 minutes.

[0104] In addition, the same procedure as in Example 4-1 was followed to form the solute film pattern of Comparative Example 4-3. The thickness of the solute film pattern formed in Comparative Example 4-3 was approximately 0.9 μm. It should be noted that in Comparative Example 4-3, due to the requirement for high decompression, a turbomolecular pump was used in conjunction with the vortex pump.

[0105] The solute film patterns of Examples 4-1 and Comparative Example 4-1 were observed using an optical microscope, and the appearance of the surface as a measure of film quality was evaluated according to the following evaluation criteria.

[0106] Evaluation criteria

[0107] A: No pinholes or significant unevenness were observed, indicating it is a smooth film.

[0108] B: There are localized unevenness in the quality of the film.

[0109] The surface appearance was evaluated, and the results showed that a good solute film pattern was obtained on the surface in Example 4-1. In contrast, it was difficult to improve the surface appearance in Comparative Example 4-1.

[0110] For the solute film patterns of Comparative Examples 4-3, the adhesion was evaluated in the same manner as in Examples 1-1 above, and the evaluation results were recorded. Figure 6 The above evaluation results show that the sealing performance was improved in Comparative Examples 4-3. However, in addition to the long decompression time (up to 28 minutes), a turbomolecular pump was required.

Claims

1. A method for forming a solute film pattern, characterized in that, The method for forming the solute film pattern includes the following steps: A liquid is coated onto a medium using an inkjet printing method. The liquid contains water, a humectant with a boiling point of 180°C or higher, a solute, and additives. The content of the humectant is 10% by mass or more and 30% by mass or less relative to the total amount. The atmosphere of the liquid coated on the medium is reduced to the vapor pressure of water at room temperature, i.e., 3000 Pa; and The atmosphere is reduced to a pressure below the vapor pressure of the humectant at room temperature, and this pressure is maintained for a certain period of time. The humectant comprises one or more of γ-butyrolactone, propylene carbonate, ethylene glycol, propylene glycol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, dipropylene glycol, and 1,2-pentanediol.

2. The method for forming a solute film pattern according to claim 1, characterized in that, The liquid coated on the medium is not subjected to heating treatment above 30°C.

3. The method for forming a solute film pattern according to claim 1, characterized in that, The total time for applying reduced pressure to the liquid coated on the medium is set to less than 20 minutes.

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