JP7700469B2 - Screen printing inks and prints - Google Patents

Description

The present invention relates to a screen printing ink and a printed matter produced using the same.

Conventionally, screen printing inks have been used in a variety of applications, such as stickers, cards, automobile meters, and nameplates, and environmental suitability, such as humidity resistance, is required. After printing the screen printing ink on a substrate, it is common for the ink to be used in a form in which the surface is protected by applying an overcoat agent or the like.

For example, screen printing inks that use polyester resin as a binder resin are used for inks on polyester substrates (polyethylene terephthalate substrates). On the other hand, many different substrates are used for screen printing, and polyester-based inks, for example, can lack adhesion and pigment dispersibility on vinyl chloride substrates.

For example, Patent Document 1 discloses a printing ink that uses a vinyl chloride-vinyl acetate copolymer and an acrylic resin as the binder resin, but the ink described in this invention only uses organic solvents with low boiling points, which raises concerns about poor printability when screen printing is performed. In addition, the amount of binder resin in the ink is insufficient, raising concerns about adhesion to the substrate.

For example, Patent Document 2 discloses a screen printing ink that uses a vinyl chloride-vinyl acetate copolymer and an acrylic resin as the binder resin, but the molecular weight of the acrylic resin is large, which may affect the ink's stability over time, particularly at low temperatures, and the leveling and transfer properties during screen printing.

Therefore, no screen printing ink has been reported that satisfies printability such as low-temperature stability over time, leveling properties, and transferability, as well as moisture-resistant adhesion properties.

WO2016/121141 Brochure JP 2004-231805 A

The object of the present invention is to provide a screen printing ink and printed matter that have excellent low-temperature stability, leveling properties, moisture-resistant adhesion, and transferability.

As a result of extensive research, the inventors discovered that the above problems could be solved, and thus completed the present invention.

That is, the present invention provides a screen printing ink comprising a binder resin and an organic solvent,
The binder resin contains a vinyl chloride copolymer resin and an acrylic resin (except when the binder resin is a vinyl chloride copolymer resin),
The acrylic resin contains an acrylic resin (a) having a weight average molecular weight of 10,000 to 80,000 and including a structural unit derived from methyl methacrylate;
The present invention relates to a screen printing ink, wherein the organic solvent contains a cyclic ketone organic solvent (A).

The present invention also relates to the above screen printing ink, which contains 25 to 45% by mass of the binder resin based on the total combined mass of the binder resin and the organic solvent.

The present invention also relates to the above screen printing ink, which contains 20 to 80 mass% of a cyclic ketone organic solvent (A) based on the total mass of the organic solvents.

In the present invention, the organic solvent further contains an organic solvent (B) having a boiling point of 120 to 250° C.,
The present invention relates to the above screen printing ink, wherein the organic solvent (B) contains at least one selected from the group consisting of glycol ether-based organic solvents, ester-based organic solvents, aliphatic organic solvents, aromatic organic solvents, and alcohol-based organic solvents.

The present invention also relates to the above screen printing ink, in which the vinyl chloride copolymer resin contains 2 to 10 mass % of vinyl alcohol units relative to the total mass of the vinyl chloride copolymer resin.

The present invention also relates to the above screen printing ink, which further contains a defoamer that is a non-silicone compound.

The present invention also relates to a printed matter having a printed layer made of the above-mentioned screen printing ink on a substrate.

The present invention also relates to the above printed matter in which the substrate is a label film having a polyvinyl chloride layer.

The present invention makes it possible to provide screen printing inks and printed matter that have excellent low-temperature stability, leveling properties, moisture-resistant adhesion, and transferability.

The present invention will be described in detail below, but screen printing ink may be abbreviated simply as "printing ink" or "ink", but these terms have the same meaning. In addition, the film formed by printing screen printing ink may be called a "printed layer", "ink film" or "ink layer", but these terms have the same meaning.

The screen printing ink of the present invention is a screen printing ink containing a binder resin and an organic solvent,
The binder resin contains a vinyl chloride copolymer resin and an acrylic resin (except when the binder resin is a vinyl chloride copolymer resin),
The acrylic resin includes an acrylic resin (a) having a weight average molecular weight of 10,000 to 80,000 and including a structural unit derived from methyl methacrylate;
The present invention relates to a screen printing ink, wherein the organic solvent contains a cyclic ketone organic solvent (A).

<Binder resin>
In the present invention, the binder resin refers to a resin that can function as a binding agent in the screen printing ink, and is preferably a thermoplastic resin. The binder resin includes vinyl chloride copolymer resins such as vinyl chloride-vinyl acetate copolymer resins, and acrylic resins.
The screen printing ink preferably contains 25 to 45% by mass of the binder resin based on the total amount of the binder resin and the organic solvent contained in the ink, more preferably 28 to 43% by mass, and even more preferably 30 to 40% by mass, in order to improve the low-temperature stability over time.

The vinyl chloride copolymer resin and acrylic resin preferably account for 50% or more by weight of the binder resin, and more preferably 80% or more by weight. The mass ratio of the vinyl chloride copolymer resin to the acrylic resin is preferably 95:5 to 40:60, and more preferably 90:10 to 50:50.

The binder resin may include a resin other than vinyl chloride-vinyl acetate copolymer resin and acrylic resin, such as a styrene-based resin, a polyurethane resin, a polyepoxy resin, a polyester resin, a rosin-based resin, a styrene-maleic acid resin, a dammar resin, a polycarbonate resin, a rosin-modified maleic acid resin, a rosin ester resin, a terpene resin, and other thermoplastic resins. These binder resins may be used in combination as long as the effects of the present invention are not impaired.

<Vinyl chloride copolymer resin>
The vinyl chloride copolymer resin is not particularly limited as long as it contains a vinyl chloride-derived structural unit and a structural unit derived from another monomer. Among them, a copolymer resin containing a vinyl alcohol unit is preferable. The vinyl chloride copolymer resin preferably contains 2 to 10% by mass of vinyl alcohol units relative to the entire vinyl chloride copolymer resin. The content of the vinyl alcohol units is more preferably 3 to 9% by mass, and even more preferably 4 to 8% by mass. This is because the pigment dispersibility is improved. In the present invention, the vinyl alcohol unit or vinyl alcohol-derived unit refers to a structural unit that appears to be derived from a vinyl alcohol monomer regardless of the manufacturing process (mainly saponification of a vinyl acetate-derived structural unit) when distinguishing the structural units of the copolymer derived from a vinyl monomer.
The vinyl chloride copolymer resin is preferably a vinyl chloride-vinyl acetate copolymer resin and/or a vinyl chloride-acrylic copolymer resin. It is more preferable that the vinyl chloride-vinyl acetate copolymer resin and/or the vinyl chloride-acrylic copolymer resin have a vinyl alcohol unit.

<Vinyl chloride-vinyl acetate copolymer resin>
The vinyl chloride-vinyl acetate copolymer resin is a copolymer of vinyl chloride and vinyl acetate, and the molecular weight is preferably 5,000 to 100,000, more preferably 20,000 to 70,000 in weight average molecular weight. The structural unit derived from vinyl acetate monomer in 100% by mass of the solid content of the vinyl chloride-vinyl acetate copolymer resin is preferably 1 to 10% by mass, more preferably 1 to 7% by mass, and even more preferably 1 to 5% by mass. The structural unit derived from vinyl chloride monomer is preferably 75 to 95% by mass. In this case, the solubility in organic solvents is improved, and further, the adhesion to the substrate, the film properties, the pigment dispersibility (including stability over time), etc. are improved.
In order to improve the solubility in organic solvents, it is more preferable that the polyvinyl alcohol contains a hydroxyl group derived from a saponification reaction or copolymerization, and the hydroxyl value is preferably 20 to 200 mgKOH/g. The glass transition temperature is preferably 50°C to 90°C, and more preferably 60 to 85°C.

<Vinyl chloride-acrylic copolymer resin>
The vinyl chloride-acrylic copolymer resin is mainly composed of a copolymer resin of vinyl chloride monomer and acrylic monomer. The acrylic monomer may be the same as the acrylic monomer described below, but it is preferable to include a (meth)acrylic acid hydroxyalkyl ester as a constituent unit in order to improve adhesion to the substrate and solubility in organic solvents. The acrylic monomer may be incorporated in the main chain of polyvinyl chloride in a block or random manner, or may be graft-polymerized to the side chain of polyvinyl chloride. The vinyl chloride-acrylic copolymer resin preferably has a weight average molecular weight of 10,000 to 100,000, more preferably 30,000 to 70,000. In addition, the hydroxyl value is preferably 20 to 200 mgKOH/g, and the glass transition temperature is preferably 50°C to 90°C, and even more preferably 60 to 85°C.

<Acrylic resin>
The acrylic resin used in the present invention includes an acrylic resin (a) having a structural unit derived from methyl methacrylate and having a weight average molecular weight of 10,000 to 80,000. The acrylic resin does not include the vinyl chloride copolymer resin. In the present invention, the "acrylic resin" refers to a resin having an acrylic monomer as a structural unit but not containing a structural unit derived from vinyl chloride. It is preferable that the acrylic resin contains 50% by mass or more of the structural unit derived from the acrylic monomer as a whole of the acrylic resin.
The acrylic resin (a) having a structural unit derived from methyl methacrylate and having a weight average molecular weight of 10,000 to 80,000 is preferably 50 to 100% by mass, more preferably 70 to 100% by mass, and even more preferably 90 to 100% by mass, based on the total mass of the acrylic resin.
The acrylic resin (a) has a structural unit derived from methyl methacrylate, which strengthens the film of the ink layer, and the printability can be improved by the weight average molecular weight of the acrylic resin (a) being 10,000 to 80,000. Furthermore, the organic solvent contains a cyclic ketone organic solvent (A), which improves the solubility of the vinyl chloride copolymer resin and the acrylic resin (a), and the combination of these requirements improves the pigment dispersibility and improves the characteristics.
The content of the structural unit derived from methyl methacrylate is more preferably 1 to 70% by mass, and even more preferably 5 to 60% by mass, of the total mass of the acrylic resin (a). This is because good adhesion to the substrate is improved. In addition, the weight average molecular weight must be 10,000 to 80,000, and the weight average molecular weight is preferably 20,000 to 75,000.
The glass transition temperature of the acrylic resin (a) is preferably 60 to 120° C., and more preferably 70 to 110° C. This is because the blocking resistance of the printed layer made of the printing ink is improved.
The acid value of the acrylic resin (a) is preferably 25 mgKOH/g or less, and more preferably 20 mgKOH/g or less, in order to improve stability over time.
The term "acrylic monomer" refers to a monomer having an acrylic group or a methacryloyl group, and "methacrylic and/or acrylic" may be collectively abbreviated as "(meth)acrylic." Additionally, "methacrylate and/or acrylate" may be collectively abbreviated as "(meth)acrylate."

The acrylic resin or the acrylic monomer constituting the acrylic resin (a) will be listed below, but is not limited thereto. Suitable acrylic monomers include alkyl (meth)acrylates and hydroxyl group-containing alkyl (meth)acrylates.
The acrylic monomer may be used alone or in combination of two or more kinds. Of the acrylic monomers listed below, it is more preferable that the acrylic monomer contains methyl methacrylate. It is also preferable that the acrylic monomer further contains a structural unit derived from an alkyl methacrylate (an alkyl group having two or more carbon atoms) and/or a hydroxyalkyl methacrylate. It is even more preferable that the acrylic monomer contains butyl (meth)acrylate and/or 2-hydroxyethyl (meth)acrylate.

Examples of alkyl (meth)acrylates include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, pentyl (meth)acrylate, hexyl (meth)acrylate, cyclohexyl (meth)acrylate, cyclopentyl (meth)acrylate, methylcyclohexyl (meth)acrylate, bornyl (meth)acrylate, isobornyl (meth)acrylate, dicyclopentenyl (meth)acrylate, dicyclopentanyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isooctyl (meth)acrylate, decyl (meth)acrylate, dodecyl (meth)acrylate, tetradecyl (meth)acrylate, hexadecyl (meth)acrylate, and octadecyl (meth)acrylate. Among these, the alkyl group preferably has 2 to 8 carbon atoms, and butyl (meth)acrylate is more preferred because it is easier to obtain good adhesion to the substrate.

The acrylic monomer may contain a hydroxyl group-containing alkyl (meth)acrylate, for example, hydroxyalkyl (meth)acrylate esters such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 3-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, and 8-hydroxyoctyl (meth)acrylate; glycol mono(meth)acrylates such as polyethylene glycol mono(meth)acrylate, polypropylene glycol mono(meth)acrylate, and 1,4-cyclohexanedimethanol mono(meth)acrylate; caprolactone-modified (meth)acrylate; and hydroxyethylacrylamide. Of these, 2-hydroxyethyl (meth)acrylate and 4-hydroxybutyl (meth)acrylate are preferred.

<Cyclic Ketone Organic Solvent (A)>
The cyclic ketone organic solvent (A) is preferably a solvent containing a 5- to 7-membered cyclic ketone structure in the molecule.
Examples of the 5-membered cyclic ketone solvent include cyclopentanone, 2-methyl-2-cyclopenten-1-one, 2-methylcyclopentanone, 3-methylcyclopentanone, 2-ethylcyclopentanone, 3-ethylcyclopentanone, 2,2-dimethylcyclopentanone, and 2,4,4-trimethylcyclopentanone.
Examples of the 6-membered cyclic ketone solvent include cyclohexanone, isophorone, 2-cyclohexen-1-one, 2-methylcyclohexanone, 3-methylcyclohexanone, 4-methylcyclohexanone, 4-ethylcyclohexanone, 2,6-dimethylcyclohexanone, and 2,2-dimethylcyclohexanone.
Examples of the seven-membered cyclic ketone solvent include cycloheptanone and 2-cycloheptan-1-one.
The cyclic ketone organic solvent (A) is preferably contained in an amount of 20 to 80% by mass, more preferably 30 to 70% by mass, and even more preferably 40 to 60% by mass, based on the total mass of the organic solvents, in order to improve the solubility in the resin.
The boiling point of the cyclic ketone organic solvent (A) is preferably from 120 to 250°C, and more preferably from 130 to 230°C.

<Organic Solvent (B) Having a Boiling Point of 120 to 250° C.>
In one embodiment, the screen printing ink preferably contains an organic solvent (B) having a boiling point of 120 to 250° C. Specifically, the organic solvent (B) contains at least one selected from the group consisting of glycol ether-based organic solvents, ester-based organic solvents, aliphatic organic solvents, aromatic organic solvents, and alcohol-based organic solvents (the organic solvent (B) does not include the above-mentioned cyclic ketone-based organic solvent (A)).
The organic solvent (B) is preferably contained in an amount of 30 to 70% by mass, and more preferably 40 to 60% by mass, based on the total amount of organic solvents constituting the liquid medium of the screen printing ink, in order to improve the solubility of the resin.

Examples of glycol ether organic solvents include ethylene glycol dibutyl ether, ethylene glycol monobutyl ether, ethylene glycol monohexyl ether, ethylene glycol monomethoxymethyl ether, diethylene glycol ethyl methyl ether, diethylene glycol dimethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, diethylene glycol monomethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol monobutyl ether, dipropylene glycol monomethyl ether, triethylene glycol dimethyl ether, triethylene glycol monomethyl ether, tripropylene glycol monomethyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, and propylene glycol monobutyl ether.

Examples of ester-based organic solvents include gamma-butyrolactone, cellosolve acetate, propylene glycol monomethyl ether acetate, ethylene glycol diacetate, ethylene glycol monoacetate, ethylene glycol monobutyl ether acetate, diethylene glycol diacetate, diethylene glycol monoethyl ether acetate, diethylene glycol monobutyl ether acetate, and propylene carbonate.

Aliphatic organic solvents include normal paraffin solvents, isoparaffin solvents, and cycloparaffin solvents.

Examples of aromatic organic solvents include toluene, xylene, ethylbenzene, naphthalene, tetralin, and solvent naphtha, as well as aromatic-rich solvents such as Swazol (Cosmo Oil Co., Ltd. and Maruzen Petrochemical Co., Ltd.), Solvesso (Exxon Mobil Corp.), and Cactus Fine (Japan Energy Corp.).

Examples of alcohol-based organic solvents include diacetone alcohol, N-amyl alcohol, methyl isobutyl carbinol, n-butanol, 3-methoxy-3-methyl-1-butanol, ethylene glycol, propylene glycol, 1,3-octylene glycol, diethylene glycol, dipropylene glycol, trimethylene glycol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, hexylene glycol, and 1,5-pentanediol.

Among the above, the boiling points of representative substances are shown below.
Isophorone: boiling point 215.2°C
3-Methylcyclopentanone: boiling point 145°C
Ethylene glycol monobutyl ether: boiling point 168.4°C
Gamma-butyrolactone: boiling point 204°C
A Solvent: Aliphatic organic solvent (mineral spirits), boiling point 160-200°C
Diacetone alcohol: boiling point 166°C
These may be used in mixture and in any ratio.

<Pigments>
The screen printing ink of the present invention may be used in combination with organic pigments, inorganic pigments, and extender pigments that are commonly used. As organic pigments, azo-based, phthalocyanine-based, anthraquinone-based, perylene-based, perinone-based, quinacridone-based, thioindigo-based, dioxazine-based, isoindolinone-based, quinophthalone-based, azomethine azo-based, diketopyrrolopyrrole-based, isoindoline-based pigments are suitable, but are not limited to these. C.I pigments listed in the Color Index can be used as appropriate. As inorganic pigments, titanium oxide, carbon black, aluminum paste, mica, bronze powder, chrome vermilion, yellow lead, cadmium yellow, cadmium red, ultramarine, Prussian blue, red iron oxide, yellow iron oxide, iron black, and the like are listed. As extender pigments, silica, alumina, talc, calcium carbonate, precipitated barium, and the like are preferably used. The pigment is contained in an amount of preferably 0.1 to 50% by mass, and more preferably 5 to 45% by mass, based on the total mass of the screen printing ink.

<Antifoaming agent>
The screen printing ink of the present invention preferably contains a defoaming agent. The content of the defoaming agent is preferably 0.1 to 5% by mass, and more preferably 0.3 to 4% by mass, based on the total mass of the screen printing ink. Compounds constituting the defoaming agent include acrylic resins, vinyl ether resins, butadiene resins, silicone resins, fluorine-based resins, and modified resins thereof (excluding the above-mentioned binder resins). The defoaming agent is preferably a non-silicone resin, and preferably contains at least one resin selected from acrylic resins, vinyl ether resins, and butadiene resins.
For example, commercially available defoaming agents include the BYK series (manufactured by BYK Japan KK) and the FLORAN series (manufactured by Kyoeisha Chemical Co., Ltd.).

<Leveling Agent>
The screen printing ink of the present invention preferably further contains a leveling agent. The content is preferably 0.1 to 1% by mass based on the total amount of the screen printing ink. The compound constituting the leveling agent is preferably an acrylic resin and/or a silicone resin (but does not include the above-mentioned binder resin). For example, commercially available leveling agents include the Polyflow series (manufactured by Kyoeisha Chemical Co., Ltd.). These may be used alone or in combination of two or more types.

<Other additives>
In addition, additives such as dispersants, wetting penetrants, antiskinning agents, UV absorbers, antioxidants, crosslinking agents, preservatives, antifungal agents, viscosity adjusters, and pH adjusters can be appropriately blended as needed within the range that does not impair the object of the present invention. Among them, it is preferable to use a dispersant, because this improves the jet black feeling of the printed matter. As the dispersant, an acidic dispersant is preferable.

<Production of screen printing ink>
The screen printing ink of the present invention can be prepared by any known dispersion method, for example, by mixing the required amounts of binder resin, pigment, organic solvent and additives, thoroughly stirring the mixture with a stirrer or the like, and then dispersing the mixture with a three-roll mill, paint shaker, attritor, sand mill or other dispersing machine.

<Base material>
The substrate used to form the printed matter in the present invention is not particularly limited, and examples thereof include inorganic substrates such as glass, polyester substrates such as polyethylene terephthalate, polyolefin substrates such as polyethylene, polypropylene, ethylene-vinyl acetate, and other polyolefin substrates, nylon substrates such as polyamide, acrylic substrates, polyvinyl chloride substrates, polycarbonate substrates, polyurethane substrates, and resin substrates such as epoxy substrates. Laminates of these may also be used. Vapor deposition substrates in which inorganic compounds such as silica, alumina, and aluminum are vapor-deposited on the substrate may also be used, and the vapor deposition surface may be further subjected to a coating treatment with polyvinyl alcohol or the like. Corona treatment, frame treatment, and stretching treatment may also be performed. Of the above, a polyvinyl chloride substrate consisting of only a polyvinyl chloride layer, or a film substrate having a polyvinyl chloride layer, which is a laminate having a polyvinyl chloride layer as the outermost layer, is preferable.

<Printed matter>
The printed matter of the present invention refers to a printed layer made of a screen printing ink formed on a substrate by any printing method. The printing method is preferably screen printing, and the printing conditions are preferably a cylinder press printing machine or a semi-automatic printing machine, and a printing plate made of a resin material such as nylon or polyester, or a resin material such as stainless steel.

<Label>
A label, which is one embodiment of the present invention, will now be described.
For example, if a film substrate having a polyvinyl chloride layer is used as the substrate, and screen printing is performed on the polyvinyl chloride layer, the substrate can be suitably used as a label. The label (printed matter) may be in a form in which a pressure-sensitive adhesive is applied to the printed matter and the printed matter is attached to an article, or in a form in which the printed matter is held on an article by heat shrinkage without using a pressure-sensitive adhesive, as in a shrink label, or in a form in which only the end of the printed matter is applied with an adhesive or heat seal and then wrapped around an article, as in a body-wrapped label. Either form is preferred.

The present invention will be specifically described below using examples, but the present invention is not limited to the following examples. In the present invention, unless otherwise specified, "parts" and "%" represent "parts by mass" and "% by mass", respectively.

<Measurements of various values>
(Acid value)
The measurement was performed according to the method described in JIS K0070.
(Molecular Weight and Molecular Weight Distribution)
The weight average molecular weight (Mw), number average molecular weight (Mn) and molecular weight distribution (Mw/Mn) were measured by GPC (gel permeation chromatography) and calculated as molecular weights using polystyrene as a standard substance.
GPC device: Showa Denko Shodex GPC-104
Columns: The following columns were used in series connection:
Showa Denko Shodex LF-404 x 2 Showa Denko Shodex LF-G x 2
Detector: RI (differential refractometer)
Measurement conditions: column temperature 40°C
Eluent: tetrahydrofuran Flow rate: 0.3 mL/min (glass transition temperature)
The glass transition temperature (Tg) was determined by DSC (differential scanning calorimetry). The measurement was performed using a Rigaku Corporation DSC8231 instrument, with a measurement temperature range of −70 to 250° C., a heating rate of 10° C./min, and the midpoint between the endothermic start and end temperatures due to the glass transition in the DSC curve was taken as the glass transition temperature.

<Example 1> [Preparation of screen printing ink S1]
As the binder resin, 25 parts of vinyl chloride-vinyl acetate copolymer resin (Solvine C, vinyl alcohol 0%, vinyl chloride 87% by mass, vinyl acetate 13% by mass, glass transition temperature 70°C, manufactured by Nissin Chemical Industry Co., Ltd.), 5 parts of Dianall BR-77 (acrylic resin manufactured by Mitsubishi Chemical Corporation, structural unit is 20 to 50% by mass of structural units derived from methyl methacrylate, weight average molecular weight 60,000, acid value 18 mg KOH/g, glass transition temperature 80°C), manufactured by Mitsubishi Chemical Corporation), 29 parts of cyclic ketone organic solvent cyclohexanone (boiling point 155.6°C) as organic solvent, and aromatic organic solvent Swazol 1000 (component C9 aromatic hydrocarbon, manufactured by Maruzen Petrochemical Co., Ltd.) A screen printing ink (S1) was prepared by uniformly mixing 29 parts of butyl rubber (boiling point 167° C.), 2 parts of BYK-057 (butadiene copolymer, manufactured by BYK-Chemie Japan) as a non-silicone antifoaming agent, and 10 parts of pigment (C.I. Pigment Blue 15:4) using a mixer rotary stirrer, and then passing the mixture through a three-roll disperser twice.

<Examples 2 to 22, Comparative Examples 1 to 6> [Preparation of screen printing inks S2 to S22, T1 to T6]
Screen printing inks were prepared in the same manner as in Example 1. The abbreviations in Tables 1 and 2 are shown below. The numerical values in the tables represent "parts" unless otherwise specified, and blanks indicate that no values were used.
Dianal BR-87: manufactured by Mitsubishi Chemical Corporation. Acrylic resin having a structural unit derived from methyl methacrylate as a structural unit, weight average molecular weight 25,000, acid value 10 mg KOH/g, glass transition temperature 105° C.
Paraloid B66: manufactured by The Dow Chemical Company. An acrylic resin having a structural unit derived from methyl methacrylate as a structural unit, weight average molecular weight of 70,000, acid value of 3.5 mg KOH/g, glass transition temperature of 50° C.
Solbin TA3: Vinyl chloride-acrylic copolymer resin manufactured by Nissin Chemical Industry Co., Ltd. Vinyl chloride unit 83% by mass Glass transition temperature 65°C
Solbin A: Vinyl chloride-vinyl acetate copolymer resin manufactured by Nissin Chemical Industry Co., Ltd. Vinyl chloride unit 92% by mass Vinyl alcohol unit 3% by mass Glass transition temperature 76°C
Solbin TAO: Vinyl chloride-vinyl acetate copolymer resin manufactured by Nissin Chemical Industry Co., Ltd. Vinyl chloride unit: 91% by mass Vinyl alcohol unit: 7% by mass Glass transition temperature: 77°C
Solbin TA5R: Vinyl chloride-vinyl acetate copolymer resin manufactured by Nissin Chemical Industry Co., Ltd. Vinyl chloride unit: 88% by mass Vinyl alcohol unit: 11% by mass Glass transition temperature: 78°C
The weight average molecular weight of each of the above vinyl chloride copolymer resins is in the range of 30,000 to 70,000.
Shin-Etsu Silicon KF-96-1000CS: Silicone-based defoamer (manufactured by Shin-Etsu Chemical Co., Ltd.)
Dianaru BR-80: Acrylic resin manufactured by Mitsubishi Chemical Corporation, weight average molecular weight 100,000
Acrylic resin A: an acrylic resin having a weight average molecular weight of 8,000 and a glass transition temperature of 70° C., which has a structural unit derived from methyl methacrylate. Isophorone: a boiling point of 215.2° C.
3-Methylcyclopentanone: boiling point 145°C
Ethylene glycol monobutyl ether: boiling point 168.4°C
Gamma-butyrolactone: boiling point 204°C
A Solvent: Aliphatic organic solvent (mineral spirits), boiling point 160-200°C
Diacetone alcohol: boiling point 166°C
Vylon 200: Amorphous polyester resin manufactured by Toyobo Co., Ltd.

<Printing with Screen Printing Ink S1>
A label film having a polyvinyl chloride layer (Oji Tack Co., Ltd., PVCW80/F93/YW16, 80 μm) was used as a substrate, and the above-mentioned screen printing ink S1 was screen-printed onto the substrate using a screen printing plate (NBC Meshtec Co., Ltd., L-SCREEN, 100-035/255PW) to form a pattern, thereby producing a screen print.

<Examples 1 to 22, Comparative Examples 1 to 6> [Printing with screen printing inks S1 to S22, T1 to T6]
Prints were prepared in the same manner as in Example 1, except that the screen printing ink S1 used in Example 1 was changed to the screen printing inks shown in Table 2.

<Evaluation of Screen Printing Inks and Prints>
The screen printing inks and printed matter obtained in the above Examples and Comparative Examples were evaluated as follows. The evaluation results are shown in Tables 1 and 2.

<Low temperature stability>
The screen printing inks obtained in Examples 1 to 22 and Comparative Examples 1 to 6 were each stored at -5°C for 5 days. The change in viscosity before and after storage was evaluated. The evaluation results were based on the following criteria:
A (Excellent): Viscosity change is less than 10%.
B (good): Viscosity change is 10% or more and less than 20%.
C (poor): Viscosity change is 20% or more.
The industrially applicable levels are A and B.

<Evaluation of Leveling Property>
Evaluations were carried out using the prints obtained in Examples 1 to 22 and Comparative Examples 1 to 6. The evaluation results were based on the following criteria: "Print unevenness" refers to a state in which the color shading of the print layer is non-uniform.
A (Excellent): Less than 5% of the area in the pattern is unevenly printed.
B (good): Print unevenness is present in an area of 5% or more and less than 20% of the pattern.
C (bad): 20% or more of the area in the pattern has printing unevenness.
The industrially applicable levels are A and B.

<Moisture resistance and adhesion>
Evaluations were carried out using the prints obtained in Examples 1 to 22 and Comparative Examples 1 to 6. After exposing the prints to an atmosphere at a temperature of 40° and a humidity of 80% for 24 hours, a 12 mm wide adhesive tape (cellophane tape manufactured by Nichiban Co., Ltd.) was applied to the printed surface, which was then quickly peeled off and the appearance of the printed surface was visually evaluated. The evaluation results were judged based on the following criteria.
A (Excellent): The ink film on the printed surface does not peel off at all.
B (Good): The peeled area of the ink film is 5% or more and less than 20%.
C (bad): The peeled area of the ink film is 20% or more.
The industrially applicable levels are A and B.

<Evaluation of metastatic potential>
Evaluations were carried out using the screen printing inks obtained in Examples 1 to 22 and Comparative Examples 1 to 6. In the following evaluations, the transfer rate refers to the weighted calculated value of the mass of ink transferred per unit area in one printing run. The evaluation results were based on the following criteria:
A (Excellent): The transfer rate of printing ink is 90% by mass or more.
B (good): The transfer rate of the printing ink is 80% by mass or more and less than 90% by mass.
C (poor): The transfer rate of the printing ink is less than 80% by mass.
The industrially applicable levels are A and B.

The present invention has been made to solve the above problems, and makes it possible to provide a screen printing ink and a printed matter that are excellent in low-temperature stability over time, leveling properties, moisture-resistant adhesion, and printability.
In Comparative Example 1 using the cyclic ketone organic solvent (A), the low-temperature stability over time, the leveling property, and the transferability were poor. In Comparative Example 3 using a different type of binder resin, the low-temperature stability over time, the leveling property, and the moisture-resistant adhesion were poor. In Comparative Example 6 using an acrylic resin with a high weight-average molecular weight, the low-temperature stability over time, the leveling property, and the transferability were poor. In Comparative Example 5 using an acrylic resin with a low weight-average molecular weight, the low-temperature stability over time and the moisture-resistant adhesion were poor.

Claims (6)

A screen printing ink comprising a binder resin and an organic solvent,
The binder resin contains a vinyl chloride copolymer resin and an acrylic resin (except when the binder resin is a vinyl chloride copolymer resin),
The acrylic resin contains an acrylic resin (a) having a weight average molecular weight of 10,000 to 80,000 and including a structural unit derived from methyl methacrylate;
The binder resin is contained in an amount of 23.5 to 45% by mass based on the total combined mass of the binder resin and the organic solvent,
The organic solvent contains a cyclic ketone organic solvent (A) ,
The cyclic ketone organic solvent (A) is contained in an amount of 17.9 to 85% by mass based on the total mass of the organic solvent,
The organic solvent further contains an organic solvent (B) having a boiling point of 120 to 250° C.,
The organic solvent (B) contains at least one selected from the group consisting of glycol ether-based organic solvents, ester-based organic solvents, aliphatic organic solvents, aromatic organic solvents, and alcohol-based organic solvents.
Screen printing inks (excluding ink compositions used for thermal transfer) . 2. The screen printing ink according to claim 1 , wherein the vinyl chloride copolymer resin contains 2 to 10% by mass of vinyl alcohol units based on the total mass of the vinyl chloride copolymer resin. 3. The screen printing ink according to claim 1, further comprising a defoaming agent which is a non-silicone compound. A printed matter having a printed layer comprising the screen printing ink according to claim 1 on a substrate. 5. The printed matter according to claim 4 , wherein the substrate is a film substrate having a polyvinyl chloride layer. A method for producing a printed matter having a printing layer made of a screen printing ink, comprising the steps of:
The method includes a step of screen printing the screen printing ink on a substrate to form a printed layer,
The screen printing ink comprises a binder resin and an organic solvent,
The binder resin contains a vinyl chloride copolymer resin and an acrylic resin (except when the binder resin is a vinyl chloride copolymer resin),
The acrylic resin contains an acrylic resin (a) having a weight average molecular weight of 10,000 to 80,000 and including a structural unit derived from methyl methacrylate;
The binder resin is contained in an amount of 23.5 to 45% by mass based on the total combined mass of the binder resin and the organic solvent,
The organic solvent contains a cyclic ketone organic solvent (A),
The cyclic ketone organic solvent (A) is contained in an amount of 17.9 to 85% by mass based on the total mass of the organic solvent,
The organic solvent further contains an organic solvent (B) having a boiling point of 120 to 250° C.,
The organic solvent (B) contains at least one selected from the group consisting of glycol ether-based organic solvents, ester-based organic solvents, aliphatic organic solvents, aromatic organic solvents, and alcohol-based organic solvents.
A method for producing printed matter.