Treatment liquid for screen-printing plate

Abstract

To provide a treatment liquid for a screen-printing plate that is excellent in storage stability at low temperature.SOLUTION: A treatment liquid for a screen-printing plate has a ratio of storage elastic modulus at 15°C after being left at -20°C to storage elastic modulus at 15°C before being left at -20°C is 10 or less.SELECTED DRAWING: None

Description

[Technical field]

[0001] An embodiment of the present invention relates to a treatment liquid for a screen printing plate. [Background technology]

[0002] A screen printing plate used in stencil printing such as screen printing can be obtained by a method called thermal plate making, in which a thermoplastic resin film of a thermal stencil master containing a thermoplastic resin film and a porous support is selectively heated by a thermal head or the like to melt and perforate the thermoplastic resin film, thereby forming perforations corresponding to an image. As the thermal stencil master, for example, a thermal screen master using a screen gauze as the porous support can be used.

[0003] The thermoplastic resin film used for thermal screen masters is generally thin, and when printing in large quantities, tiny holes (pinholes) can appear in the film, resulting in tiny dots being printed in unintended places on the printed material. Patent Document 1 proposes a method of reinforcing the film by applying a resin solution to a screen printing plate after platemaking, leaving the resin solution only in the unmade areas, and then drying to form a resin film. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 7-89043 Summary of the Invention [Problem to be solved by the invention]

[0005] An object of an embodiment of the present invention is to provide a treatment liquid for a screen printing plate that has excellent storage stability at low temperatures. [Means for solving the problem]

[0006] One embodiment of the present invention relates to a treatment liquid for screen printing plates, in which the ratio of the storage modulus at 15°C after standing at -20°C to the storage modulus at 15°C before standing at -20°C is 10 or less. Effect of the Invention

[0007] According to an embodiment of the present invention, it is possible to provide a treatment liquid for a screen printing plate that has excellent storage stability at low temperatures. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] Hereinafter, the embodiments of the present invention will be described in detail, but it goes without saying that the present invention is not limited to these embodiments and various modifications and changes may be made.

[0009] The treatment liquid for a screen printing plate according to the embodiment (hereinafter, also referred to as the "treatment liquid") is a treatment liquid for a screen printing plate in which the ratio of the storage modulus at 15°C after being left at -20°C to the storage modulus at 15°C before being left at -20°C (hereinafter, also referred to as the "storage modulus ratio X") is 10 or less.

[0010] In order to reinforce a screen printing plate obtained by thermal plate making, there is a method in which a treatment liquid such as a resin-containing liquid described in Patent Document 1 is applied as a reinforcing agent to the screen printing plate after plate making. However, for example, if the treatment liquid containing the resin is left at a low temperature, it may gel. In general, a gelled liquid is difficult to use as a coating liquid. Without being bound by theory, it is thought that the mechanism by which a liquid stored at low temperatures gels is that the thermal motion of molecules decreases at low temperatures, making it easier for the polymer chains of the components contained in the liquid to interact with each other, resulting in the formation of a three-dimensional mesh structure due to contact between the polymer chains, and water is trapped in the gaps in this three-dimensional mesh structure to form a gel.

[0011] The present inventors have found that, in a treatment liquid that gels when left at low temperatures, the storage modulus after being left at low temperatures differs significantly from that before being left at low temperatures, whereas, in a treatment liquid that does not gel when left at low temperatures, the storage modulus after being left at low temperatures does not change significantly from that before being left at low temperatures, and that when the ratio of the storage modulus at 15°C after being left at -20°C to the storage modulus at 15°C before being left at -20°C ("storage modulus ratio X") of a treatment liquid is 10 or less, the treatment liquid has excellent storage stability at low temperatures and is not likely to gel even when left at low temperatures.

[0012] Examples of the method for adjusting the ratio X of the storage modulus of the treatment liquid include a method for suppressing contact between hydroxyl groups in the resin contained in the treatment liquid by reducing the number of hydroxyl groups or by providing a functional group with large steric hindrance in the side chain, and a method for lowering the freezing temperature of the solvent in the treatment liquid. Examples of the method for reducing the number of hydroxyl groups include, for example, lowering the degree of saponification in the case of a compound such as a polyvinyl alcohol resin. Examples of the method for lowering the freezing temperature of the solvent in the treatment liquid include, for example, adding a water-soluble organic solvent with a high boiling point to the treatment liquid. If the freezing temperature of the solvent in the treatment liquid is lowered, the temperature at which a three-dimensional network structure is formed can be lowered. The method for adjusting the storage modulus ratio X of the treatment liquid is not limited to the above-mentioned method. However, the storage modulus ratio X of the treatment liquid may be adjusted, for example, by using only one of the above-mentioned methods or a combination of two or more of them.

[0013] From the viewpoint of storage stability at low temperatures, the ratio X of the storage modulus of the processing liquid is preferably 10 or less, more preferably 8.0 or less, even more preferably 6.0 or less, still more preferably 4.0 or less, and even more preferably 3.0 or less.

[0014] From the viewpoint of good coatability of the treatment liquid on the screen printing plate, the ratio X of the storage modulus of the treatment liquid is preferably 0.1 or more, more preferably 0.5 or more, and even more preferably 1.0 or more. When the ratio X of the storage modulus of the treatment liquid is within this range, the treatment liquid applied to the non-perforated parts is less likely to flow out of the perforated parts, and the treatment liquid tends to remain on the screen printing plate.

[0015] The ratio X of the storage elastic modulus of the treatment liquid is, for example, preferably from 0.1 to 10, more preferably from 0.1 to 8.0, even more preferably from 0.5 to 6.0, still more preferably from 0.5 to 4.0, and even more preferably from 1.0 to 3.0.

[0016] The storage modulus is the component of energy generated by strain due to an external force that is stored inside a substance. In other words, the storage modulus can be an index of the hardness of a substance. The storage modulus of a treatment liquid at 15°C is a value measured at a measurement temperature of 15°C and a frequency of 1 Hz. A rheometer can be used to measure the storage modulus of a treatment liquid.

[0017] The storage modulus of the treatment liquid at 15°C before being left at -20°C and the storage modulus at 15°C after being left at -20°C can be specifically measured, for example, by the method described in the Examples.

[0018] The storage modulus ratio X can be calculated by the following formula using the storage modulus (Pa) at 15°C before standing at -20°C (in the formula below, "storage modulus A (Pa) at 15°C") of the treatment liquid and the storage modulus (Pa) at 15°C after standing at -20°C (in the formula below, "storage modulus B (Pa) at 15°C") of the treatment liquid. Storage modulus ratio X = (storage modulus B at 15°C (Pa)) / (storage modulus A at 15°C (Pa))

[0019] In measuring the storage modulus ratio X, the time for which the treatment liquid is left standing at -20°C is not particularly limited and can be appropriately selected, but is preferably 1 second to 5 minutes, more preferably 5 seconds to 1 minute, and even more preferably 10 seconds to 40 seconds. The rate at which the temperature of the treatment liquid is lowered from 15° C. to −20° C. is not particularly limited and may be appropriately selected, but is preferably 1 to 5° C. / min, and more preferably 2 to 4° C. / min. The rate at which the temperature of the treatment liquid is raised from −20° C. to 15° C. is also not particularly limited and may be appropriately selected, but is preferably 1 to 5° C. / min, and more preferably 2 to 4° C. / min.

[0020] The treatment liquid may contain a resin, which may be, for example, a water-dispersible resin, a water-soluble resin, or a combination thereof.

[0021] Since the water-dispersible resin exhibits water dispersibility, it can be dispersed in water in particulate form without dissolving in water to form an oil-in-water (O / W) type resin emulsion. The water-dispersible resin is preferably contained in the treatment liquid in a dispersed state as resin particles. The water-dispersible resin may be any of anionic resins, cationic resins, amphoteric resins, and nonionic resins. The water-dispersible resin may be a resin in which functional groups are present on the surface of the resin particles, such as a self-emulsifying resin, or a resin that has been subjected to a surface treatment such as attaching a dispersant to the surface of the resin particles.

[0022] Examples of the water-dispersible resin include urethane resin, (meth)acrylic resin, vinyl chloride resin, styrene-maleic anhydride copolymer resin, vinyl acetate-ethylene copolymer resin, etc. The water-dispersible resin is not particularly limited, but may be, for example, one of these resins or a combination of two or more of them. (Meth)acrylic means methacryl, acrylic, or both of them.

[0023] The water-dispersible resin is preferably a water-dispersible urethane resin, a water-dispersible (meth)acrylic resin, a water-dispersible vinyl chloride resin, or a combination thereof.

[0024] The weight average molecular weight (Mw) of the water-dispersible resin is not particularly limited, but is preferably 1000 to 100000. Here, the weight average molecular weight of the resin is a value calculated in terms of polystyrene by a gel permeation chromatography (GPC) method. Hereinafter, the same applies to the weight average molecular weight unless otherwise specified.

[0025] The water-dispersible resin can be blended in the treatment liquid as an oil-in-water (O / W) type resin emulsion that becomes particulate in the treatment liquid, and it is preferable that the resin be in the form of resin particles in the treatment liquid.

[0026] Commercially available emulsions of water-dispersible resins include, for example, "ADEKA BONTITOR HUX840" manufactured by ADEKA CORPORATION, "IMPLANIEL DLC-F" manufactured by Sumitomo Covestro Urethane Co., Ltd., and "SUPERFLEX 300" manufactured by Daiichi Kogyo Seiyaku Co., Ltd. (all trade names).

[0027] Examples of water-soluble resins include polyester resins, polyvinyl alcohol resins, poly(meth)acrylic acid, neutralized poly(meth)acrylic acid, (meth)acrylic acid / maleic acid copolymers, (meth)acrylic acid / sulfonic acid copolymers, and styrene / maleic acid copolymers. These may be used alone or in combination of two or more. (Meth)acrylic acid means methacrylic acid, acrylic acid, or both of these.

[0028] Examples of polyvinyl alcohol resins include polyvinyl alcohol that can generally be obtained by saponifying polyvinyl acetate, and polyvinyl alcohol resins having a 1,2-ethanediol structure, which will be described later.

[0029] From the viewpoint of suppressing contact between hydroxyl groups of the resin and further improving the storage stability of the treatment liquid at low temperatures, it is preferable that the polyvinyl alcohol resin has a functional group with large steric hindrance in the side chain. From the same viewpoint, for example, a polyvinyl alcohol resin having a 1,2-ethanediol structure (hereinafter, sometimes referred to as "polyvinyl alcohol resin A") is preferable. It is preferable that the polyvinyl alcohol resin A has a 1,2-ethanediol structure in the side chain. For example, the polyvinyl alcohol resin A includes a copolymer containing a structural unit having a structure derived from butenediol such as 3-butene-1,2-diol.

[0030] The degree of saponification of the polyvinyl alcohol resin is not particularly limited, and may be appropriately selected in consideration of, for example, the structure of the resin. The degree of saponification of the polyvinyl alcohol resin may be, for example, 99.5 mol% or less, 95 mol% or less, 90 mol% or less, 85 mol% or less, or 80 mol% or less. From the viewpoint of further improving the storage stability of the treatment liquid at low temperatures by reducing the number of hydroxyl groups of the resin and reducing the frequency of contact between hydroxyl groups, it is preferable that the degree of saponification of the polyvinyl alcohol resin is low. From this viewpoint, for example, in the case of polyvinyl alcohol that does not have a side chain having a functional group with large steric hindrance, it is more preferable that the degree of saponification is low, for example, the degree of saponification of polyvinyl alcohol is preferably 95 mol% or less, more preferably 90 mol% or less, even more preferably 85 mol% or less, and even more preferably 80 mol% or less.

[0031] The degree of saponification of the polyvinyl alcohol resin may be, for example, 50 mol % or more, or 60 mol % or more. The degree of saponification of the polyvinyl alcohol resin may be, for example, 50 to 99.5 mol %, 50 to 95 mol %, 50 to 90 mol %, 50 to 85 mol %, or 60 to 80 mol %.

[0032] In this specification, the degree of saponification of the polyvinyl alcohol resin is a value measured by a method in accordance with JIS K6726.

[0033] The degree of polymerization of the polyvinyl alcohol resin is not particularly limited, and may be, for example, 200 or more, 400 or more, or 1000 or more. The degree of polymerization of the polyvinyl alcohol-based resin may be, for example, 5000 or less, 2500 or less, 2000 or less, or 1500 or less. The degree of polymerization of the polyvinyl alcohol-based resin may be, for example, 200 to 5000, 200 to 2500, 200 to 2000, or 400 to 1500.

[0034] The method for producing the polyvinyl alcohol resin is not particularly limited. For example, polyvinyl alcohol can be obtained by saponifying polyvinyl acetate. Also, for example, polyvinyl alcohol resin A can be obtained by polymerizing raw material monomers or saponifying raw material polymers.

[0035] As the water-soluble resin, for example, commercially available products may be used. For example, commercially available polyvinyl alcohol products include "Denka Poval MP-10" manufactured by Denka Co., Ltd., and "Poval JL-05E", "Poval JF-20", and "Poval JF-04" manufactured by Nippon Vinyl Acetate Poval Co., Ltd. Commercially available polyvinyl alcohol resin A products include "Nichigo G Polymer OKS-1009", "Nichigo G Polymer OKS-8077", and "Nichigo G Polymer OKS-8089" manufactured by Mitsubishi Chemical Corporation (all trade names).

[0036] The water-soluble resins may be used alone or in combination of two or more.

[0037] The treatment liquid may contain one type of resin alone or two or more types in combination. The resin is preferably 1% by mass or more, more preferably 5% by mass or more, and even more preferably 10% by mass or more, based on the total amount of the treatment liquid. On the other hand, the resin is preferably 40% by mass or less, more preferably 30% by mass or less, and even more preferably 20% by mass or less, based on the total amount of the treatment liquid. The resin is, for example, preferably 1 to 40% by mass, more preferably 5 to 30% by mass, and even more preferably 10 to 20% by mass, based on the total amount of the treatment liquid.

[0038] The treatment liquid preferably contains water. The water is not particularly limited, but is preferably one that contains as few ionic components as possible. In particular, from the viewpoint of storage stability of the treatment liquid, it is preferable that the content of polyvalent metal ions such as calcium is small. As the water, for example, ion-exchanged water, distilled water, ultrapure water, etc. may be used.

[0039] The content of water is preferably 60% by mass or more, more preferably 70% by mass or more, and even more preferably 80% by mass or more, based on the total amount of the treatment liquid. On the other hand, the content of water is preferably 99% by mass or less, more preferably 95% by mass or less, and even more preferably 90% by mass or less, based on the total amount of the treatment liquid. The content of water is, for example, preferably 60 to 99% by mass, more preferably 70 to 95% by mass, and even more preferably 80 to 90% by mass, based on the total amount of the treatment liquid.

[0040] The total amount of the resin and water is preferably 90% by mass or more, more preferably 95% by mass or more, and even more preferably 97% by mass or more, based on the total amount of the treatment liquid. The total amount of the resin and water may be, for example, 100% by mass or less or 99% by mass or less, based on the total amount of the treatment liquid. The total amount of the resin and water may be, for example, 90 to 100% by mass, 95 to 100% by mass, 97 to 100% by mass, or 99 to 100% by mass, based on the total amount of the treatment liquid.

[0041] The treatment liquid may contain a water-soluble organic solvent. As the water-soluble organic solvent, an organic compound that is liquid at room temperature and dissolves in water can be used, and it is preferable to use a water-soluble organic solvent that is uniformly mixed with the same volume of water at 20°C under 1 atmosphere. For example, lower alcohols such as methanol, ethanol, 1-propanol, isopropanol, 1-butanol, 2-butanol, isobutanol, and 2-methyl-2-propanol; glycols such as ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, and polypropylene glycol; glycerins such as glycerin, diglycerin, triglycerin, and polyglycerin; acetins such as monoacetin and diacetin; ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monopropyl ether, ethylene glycol monobutyl ether, diethyl ether, ethyl ... Examples of the glycol ethers that can be used include: glycol ethers such as ethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monopropyl ether, diethylene glycol monobutyl ether, triethylene glycol monomethyl ether, triethylene glycol monoethyl ether, triethylene glycol monopropyl ether, triethylene glycol monobutyl ether, tetraethylene glycol monomethyl ether, tetraethylene glycol monoethyl ether, tetraethylene glycol dimethyl ether, and tetraethylene glycol diethyl ether; triethanolamine, 1-methyl-2-pyrrolidone, 1,3-dimethyl-2-imidazolidinone, β-thiodiglycol, and sulfolane.

[0042] The boiling point of the water-soluble organic solvent is preferably 100° C. or higher, and more preferably 150° C. or higher.

[0043] These water-soluble organic solvents may be used alone or in combination of two or more kinds as long as they form a single phase with water. The content of the water-soluble organic solvent in the ink may be, for example, 1 to 10 mass %, 1 to 5 mass %, or 2 to 4 mass %.

[0044] From the viewpoint of lowering the freezing temperature of the solvent in the treatment liquid and further improving the storage stability at low temperatures, the treatment liquid may contain a water-soluble organic solvent having a high boiling point. From this viewpoint, the treatment liquid preferably contains a water-soluble organic solvent having a boiling point of 150° C. or higher, and more preferably contains a water-soluble organic solvent having a boiling point of 170° C. or higher.

[0045] On the other hand, when the treatment liquid contains a water-soluble organic solvent having a high boiling point, the drying property of the resin may be reduced. From the viewpoint of the drying property of the treatment liquid, the amount of the water-soluble organic solvent having a boiling point of 150° C. or more in the treatment liquid is preferably 4% by mass or less, more preferably 3% by mass or less, even more preferably less than 1% by mass, even more preferably 0.5% by mass or less, and even more preferably no water-soluble organic solvent having a boiling point of 150° C. or more is contained.

[0046] The treatment liquid may further contain additives such as a surfactant, a pigment, an antifreeze agent, and an antistatic agent, if necessary.

[0047] The method for producing the treatment solution is not particularly limited. For example, the treatment solution can be produced by mixing each material at once or in portions.

[0048] The processing liquid can be preferably used for a screen printing plate obtained by thermal plate making. The screen printing plate is not particularly limited, and may be, for example, one obtained by making a thermal screen master by thermal plate making.

[0049] The thermal screen master preferably comprises a screen gauze and a thermoplastic resin film. The thermal screen master may preferably be a screen mesh and a thermoplastic resin film bonded together using an adhesive. The thermal screen master preferably includes, for example, a screen mesh, an adhesive layer formed using an adhesive, and a thermoplastic resin film in this order.

[0050] The screen gauze may be any material that is not substantially perforated by the heat of the thermal head and allows ink to pass through during printing. For example, gauze made from fibers such as polyester, nylon, rayon, stainless steel, silk, and cotton can be used.

[0051] The thickness of the screen mesh is usually 40 to 270 μm, and preferably 50 to 150 μm. The mesh number of the screen gauze (the number of fibers per inch) is usually 40 to 500, and preferably 50 to 350. The mesh numbers in the vertical and horizontal directions may be the same or different, as long as they are within the above mesh number range.

[0052] Examples of the thermoplastic resin film include polyethylene-based resin film, polypropylene-based resin film, polyester-based resin film, polyamide-based resin film, polyvinyl chloride-based resin film, polyvinylidene chloride-based resin film, etc. Among these, polyester-based resin film can be preferably used. Examples of the polyester-based resin include polyethylene terephthalate, polyethylene-2,6-naphthalate, polybutylene terephthalate, ethylene terephthalate / ethylene isophthalate copolymer, butylene terephthalate / ethylene terephthalate copolymer, butylene terephthalate / hexamethylene terephthalate copolymer, hexamethylene terephthalate / 1,4-cyclohexanedimethylene terephthalate copolymer, ethylene terephthalate / ethylene-2,6-naphthalate copolymer, etc. The thermoplastic resin film may contain various additives such as pigments, viscosity modifiers, dispersants, dyes, lubricants, crosslinking agents, and plasticizers, as necessary.

[0053] The thickness of the thermoplastic resin film may be any thickness that allows thermal digital screen printing, and is usually 0.5 to 10 μm, and preferably 1 to 5 μm.

[0054] The thermoplastic resin film preferably has a shrinkability suitable for easy melt perforation by thermal digital screen making, and may be suitably uniaxially or biaxially stretched.

[0055] The thermal screen master may be, for example, a commercially available product, such as "RISO Digital Screen Master QS120P-113-50" manufactured by Riso Kagaku Corporation. The thermal screen master can be produced, for example, by a method including adhering a screen gauze and a thermoplastic resin film with an adhesive.

[0056] The adhesive is not particularly limited as long as it can bond the two together so as to satisfy the printing resistance required during printing. Examples of the adhesive include water-based types, solvent-based types, solventless types, hot melt types, and photocurable types such as infrared, visible light, ultraviolet, and electron beam types.

[0057] Specific examples of solvent-type adhesives include those in which vinyl acetate, polyester, (meth)acrylic, or other resins are dissolved in the organic solvents listed below. Specific examples of organic solvents include aliphatic hydrocarbons, aromatic hydrocarbons, alcohols, ketones, esters, ethers, aldehydes, carboxylic acids, amines, low-molecular-weight heterocyclic compounds, and oxides, such as hexane, heptane, octane, benzene, toluene, xylene, methyl alcohol, ethyl alcohol, isopropyl alcohol, n-propyl alcohol, butyl alcohol, ethylene glycol, diethylene glycol, propylene glycol, glycerin, acetone, methyl ethyl ketone, ethyl acetate, propyl acetate, ethyl ether, tetrahydrofuran, 1,4-dioxane, formic acid, acetic acid, propionic acid, formaldehyde, acetaldehyde, methylamine, ethylenediamine, dimethylformamide, pyridine, and ethylene oxide. Specific examples of photocurable adhesives include those mainly composed of monomers, oligomers, and photopolymerization initiators, and more specifically, include polyester-based (meth)acrylate, urethane-based (meth)acrylate, epoxy-based (meth)acrylate, and polyol-based (meth)acrylate photocurable adhesives, etc. These adhesives may contain additives such as antistatic agents, lubricants, tackifiers, fillers, and leveling agents, as necessary.

[0058] The method of bonding the screen gauze and the thermoplastic resin film with an adhesive is not particularly limited. For example, the screen gauze and the thermoplastic resin film may be bonded to each other by applying an adhesive using a roll coater or the like.

[0059] The method of applying the adhesive is not particularly limited. For example, the adhesive may be applied to the screen mesh using a roll coater or the like, or the adhesive may be applied to the screen mesh by immersing the screen mesh in the adhesive diluted with a solvent.

[0060] The amount of adhesive applied is usually 0.05 to 10.0 g / m 2From the viewpoint of adhesive strength, the amount of application is in the range of 0.05 g / m 2 From the viewpoint of ink permeability and good perforation, the application amount is preferably 10.0 g / m 2 The following is preferred:

[0061] A release agent may be applied to the outer surface of the thermoplastic resin film of the thermal screen master (i.e., the surface opposite to the side where the screen gauze is arranged) to provide a release layer in order to prevent sticking during perforation. The method of applying the release agent is not particularly limited, but it is preferable to apply it using a roll coater, gravure coater, reverse coater, bar coater, etc. As the release agent, silicone oil, silicone resin, fluorine resin, surfactant, etc. may be used. In addition, various additives such as antistatic agents, heat resistance agents, antioxidants, organic particles, inorganic particles, and pigments may be mixed into the release agent. Furthermore, various additives such as dispersing agents, surfactants, preservatives, and antifoaming agents may be added to the coating solution of the release agent in order to improve dispersibility in water. The thickness of the release layer is preferably 0.005 μm to 0.4 μm, more preferably 0.01 μm to 0.4 μm, from the viewpoints of running property during perforation and contamination resistance of the thermal head (TPH).

[0062] The method for thermally making a thermal screen master is not particularly limited. The thermal screen master can be used as a screen printing plate by making a plate from the thermal screen master using a thermal plate making device or the like that uses a thermal head.

[0063] The method for treating a screen printing plate according to the embodiment is a method for treating a screen printing plate, which includes treating the screen printing plate with the treatment liquid described above. The treatment liquid and the screen printing plate are as described above.

[0064] The method for treating the screen printing plate with the treatment liquid is not particularly limited.

[0065] The treatment liquid is preferably applied to the surface of the screen printing plate on the mesh side.

[0066] The method for applying the treatment liquid is not particularly limited, but it is preferable to drop the treatment liquid onto the surface of the screen printing plate using, for example, a dropper or a dispenser, and then spread the treatment liquid over the area to which it is desired to apply it using a squeegee or the like.

[0067] The amount of the processing solution applied was 10 g / m 2 More than 20 g / m is preferable. 2 The amount of the processing solution applied is preferably 100 g / m2 in total. 2 The amount of the treatment liquid applied is, for example, 10 to 100 g / m 2 is preferable, and 20 to 100 g / m 2 is more preferred.

[0068] From the viewpoint of removing the solvent in the treatment liquid and ensuring the strength of the layer formed from the treatment liquid, it is preferable to dry the treatment liquid on the screen printing plate after applying the treatment liquid to the screen printing plate. The drying method is not particularly limited, and can be appropriately selected from drying with hot air, natural drying, etc. From the viewpoint of strengthening the layer formed from the treatment liquid, drying with hot air is preferable.

[0069] The method of processing a screen printing plate may further include other steps or operations.

[0070] Stencil printing can be performed using a screen printing plate treated with the treatment liquid for screen printing plate of the embodiment. As the ink used for printing, for example, an ink that can be used for stencil printing such as screen printing can be used. Such ink may be, for example, any of water-based ink, oil-based ink, solvent ink, oil-in-water (O / W) type emulsion ink, water-in-oil (W / O) type emulsion ink, and plastisol ink.

[0071] The present disclosure includes the following embodiments. <1> A treatment liquid for a screen printing plate, in which the ratio of the storage modulus at 15°C after being left at -20°C to the storage modulus at 15°C before being left at -20°C is 10 or less. <2> The proportion of water-soluble organic solvents having a boiling point of 150° C. or higher is less than 1% by mass based on the total amount of the screen printing plate treatment liquid. <1> 2. The processing liquid for a screen printing plate according to claim 1 . <3> Contains polyvinyl alcohol resin, <1> or <2> 2. The processing liquid for a screen printing plate according to claim 1 . EXAMPLES

[0072] The present invention will be described in detail below based on examples and comparative examples, but the present invention is not limited to these examples.

[0073] <Production of processing solution> Tables 1 and 2 show the composition of the treatment liquid of each Example and Comparative Example. The materials listed in the tables were mixed to obtain the treatment liquid of each Example and Comparative Example. The contents shown in Tables 1 and 2 are the total amount of the solution or dispersion of materials blended as a solution or dispersion. For example, the resin emulsion is shown as the total amount of the resin emulsion.

[0074] Details of the materials listed in Tables 1 and 2 are given below.

[0075] Resin 1: "Nichigo G Polymer OKS-1009" (product name), manufactured by Mitsubishi Chemical Corporation, butenediol-vinyl alcohol copolymer, saponification degree 99 mol%, polymerization degree 1200 Resin 2: "Nichigo G Polymer OKS-8077" (product name), manufactured by Mitsubishi Chemical Corporation, butenediol vinyl alcohol copolymer, saponification degree 99 mol%, polymerization degree 330 Resin 3: "Nichigo G Polymer OKS-8089" (product name), manufactured by Mitsubishi Chemical Corporation, butenediol vinyl alcohol copolymer, saponification degree 86 mol%, polymerization degree 450 Resin 4: "Poval JL-05E" (product name), manufactured by Nippon Vinyl Acetate & Poval Co., Ltd., polyvinyl alcohol, saponification degree 82 mol%, polymerization degree 500 Resin 5: "Denka Poval MP-10" (product name), manufactured by Denka Co., Ltd., polyvinyl alcohol, saponification degree 72 mol%, polymerization degree 1000 Resin 6: "Poval JF-20" (product name), manufactured by Nippon Vinyl Acetate & Poval Co., Ltd., polyvinyl alcohol, saponification degree 98 mol%, polymerization degree 2000 Resin 7: "Poval JF-04" (product name), manufactured by Nippon Vinyl Acetate & Poval Co., Ltd., polyvinyl alcohol, saponification degree 98 mol%, polymerization degree 400 Resin 8: "ADEKA BONTITOR HUX-80" (product name), manufactured by ADEKA Corporation, resin emulsion (water-dispersible urethane resin), non-volatile content 37% by mass Resin 9: "Impranil DLC-F" (product name), manufactured by Sumitomo Covestro Urethane Co., Ltd., resin emulsion (water-dispersible urethane resin), non-volatile content 40% by mass Resin 10: "Superflex 300" (product name), manufactured by Daiichi Kogyo Seiyaku Co., Ltd., resin emulsion (water-dispersible urethane resin), non-volatile content 30% by mass Water-soluble organic solvent: Ethylene glycol, manufactured by Mitsubishi Chemical Corporation

[0076] <Storage modulus ratio X> The storage modulus ratios X shown in Tables 1 and 2 were obtained as follows. For each treatment liquid, a rheometer ("MCR302" (product name) manufactured by Anton Paar) was used to measure the storage modulus (Pa) at 15°C before leaving at -20°C and the storage modulus (Pa) at 15°C after leaving at -20°C for 20 seconds under the following measurement conditions.

[0077] Temperature: (Start point) 15℃ → -20℃ → (End point) 15℃ Cooling rate: 3℃ / min Heating rate: 3℃ / min Cone: Parallel cone Gap: 1mm Distortion: 0.10% of swing angle Frequency: 1Hz Normal force: 0μN

[0078] The storage modulus ratio X was calculated using the storage modulus (Pa) at 15°C before leaving at -20°C ("storage modulus A [Pa] at 15°C" in the formula below) measured above and the storage modulus (Pa) at 15°C after leaving at -20°C ("storage modulus B [Pa] at 15°C" in the formula below) according to the formula below. Storage modulus ratio X = (storage modulus B at 15°C [Pa]) / (storage modulus A at 15°C [Pa])

[0079] <Evaluation> Using the treatment liquids of each of the Examples and Comparative Examples obtained as described above, the low-temperature storage stability was evaluated as described below. Also, using the treatment liquids of each of the Examples, the drying property was evaluated as described below. The results are shown in Tables 1 and 2.

[0080] (1)Low temperature storage stability 10 ml of the treatment solution was placed in a 20 ml glass bottle and left to stand at -20°C for one week. Immediately after leaving the bottle, the presence or absence of gelation of the treatment solution was visually evaluated.

[0081] For the treatment liquids which showed no gelation immediately after being left at -20°C for one week, the viscosity change rate was calculated from the viscosities before and after being left at -20°C for one week according to the following formula. Viscosity change rate [%] = (Viscosity after leaving for 1 week at -20°C [Pa s] / Viscosity before leaving [Pa s]) x 100

[0082] The viscosity of the treatment liquid was measured at 23° C. using a rheometer ("MCR302" (product name) manufactured by Anton Paar). The measurement conditions were as follows. Cone: Φ25mm / 1° Measurement program: 0 to 500 seconds -1 (60 seconds) *500 seconds -1 Viscosity at time Temperature: 23℃

[0083] For the treatment liquid that had gelled immediately after being left at -20°C for one week, in order to evaluate whether its fluidity had recovered by heating, it was left at 50°C for a further hour, and after being left there, the treatment liquid was visually evaluated for the presence or absence of gelling.

[0084] Based on these results, the low temperature stability was evaluated according to the following evaluation criteria.

[0085] Evaluation criteria (low temperature stability) A: No gelation was observed immediately after leaving it at -20℃ for 1 week, and the viscosity change rate before and after leaving it at -20℃ for 1 week was 5% or less. B: No gelation was observed immediately after leaving the sample at -20°C for 1 week, but the viscosity change rate before and after leaving the sample at -20°C for 1 week was more than 5%. C: Gelation was observed immediately after leaving it at -20°C for one week, but no gelation was observed after leaving it at 50°C for one hour (fluidity can be restored by heating). D: Gelation was observed immediately after leaving it at -20°C for one week, and also after leaving it at 50°C for one hour (fluidity could not be restored by heating).

[0086] (2)Drying property The screen gauze side of the thermal screen master (RISO Digital Screen Master QS120P-113-50 (product name) manufactured by Riso Kagaku Corporation) is coated with 50 g / m 2 The treatment solution was applied with a squeegee so that the amount applied was 200 mm × 100 mm. After applying hot air to the coating film with a dryer, the coating film was rubbed with a crock meter and the time until the coating film no longer adhered to the cloth was measured, and the drying property was evaluated based on the following evaluation criteria.

[0087] Evaluation criteria (drying property) A: It takes less than 1 minute for the coating to disappear. B: The time it takes for the coating to disappear is more than 1 minute and less than 3 minutes. C: The time it takes for the coating to disappear is more than 3 minutes.

[0088] [Table 1]

[0089] [Table 2]

[0090] As shown in the table, the treatment solutions of Examples 1 to 8, in which the storage modulus ratio X was 10 or less, were superior in low-temperature stability to those of Comparative Examples 1 to 3, in which the storage modulus ratio X was more than 10.

Claims

1. A treatment liquid for a screen printing plate, in which the ratio of the storage modulus at 15°C after standing at -20°C to the storage modulus at 15°C before standing at -20°C is 10 or less.

2. 2. The treatment liquid for a screen printing plate according to claim 1, wherein the proportion of the water-soluble organic solvent having a boiling point of 150° C. or higher is less than 1 mass % based on the total amount of the treatment liquid for a screen printing plate.

3. The treatment liquid for a screen printing plate according to claim 1 or 2, which contains a polyvinyl alcohol-based resin.

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