JP2019104840A - Ink for printing and printed matter - Google Patents

Abstract

To provide a printing ink and a printed matter which are excellent in temporal stability, leveling property and transferability, and achieve both jet-blackness with high blackness and transparency.SOLUTION: There are provided an ink for printing that contains a carbon nanotube having an average diameter of 5-30 nm and a binder resin, in which the binder resin contains an acrylic resin having an acid value of 1 to 25 mgKOH/g and has a thixotropic index at 25°C of 1.1 to 1.9; and a printed matter printed by the ink for printing.SELECTED DRAWING: None

Description

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

As printing inks, various printing inks such as gravure printing ink, flexographic printing ink, screen printing ink, offset ink, etc. are known, among which black ink (sometimes referred to as black ink / black ink) Carbon black is mainly used as a coloring agent, and depending on the characteristics of carbon black, the color tone and the printability of the printing ink are greatly influenced. Although carbon black needs to be selected according to the required characteristics, it is difficult to maintain good dispersion stability compared to other organic pigments, and when trying to satisfy printability, print density is insufficient In many cases, it has been difficult to satisfy desired characteristics required, such as insufficient ink film characteristics when attempting to increase the printing density (Patent Document 1).

Printed materials printed with black ink using carbon black can obtain black printed materials with high hiding power due to strong coloring power by carbon black, but in recent years, the market for printed materials that are black but easy to transmit light The demand is increasing. However, depending on the carbon black content in the ink, when such a printed matter is to be obtained, if the carbon black content is increased, the desired degree of blackness can be obtained but it becomes difficult to transmit light, conversely carbon black content If the ratio is lowered, light may be easily transmitted, but the blackness may be lowered, and it has been difficult to obtain a print having compatibility between blackness and transparency.

JP, 2015-101688, A

  The problem to be solved by the present invention is to solve the above-mentioned problems, and it is excellent in temporal stability, leveling property, and transferability, and it is a print that can achieve both jet-blackness and transparency with a high degree of blackness. It is to provide ink and printed matter.

  As a result of earnest research, the present inventors have found that the above problems can be solved, and have completed the present invention. That is, the present invention is a printing ink comprising a carbon nanotube having an average diameter of 5 to 30 nm and a binder resin, wherein the binder resin contains an acrylic resin having an acid value of 1 to 25 mg KOH / g, 25 ° C. Printing ink having a thixotropic index of 1.1 to 1.9.

  Moreover, this invention relates to the said printing ink whose glass transition temperature of the said acrylic resin is 60-110 degreeC.

  The present invention further relates to the above-mentioned printing ink comprising 0.1 to 2% by mass of an antifoaming agent.

  Further, the present invention relates to the printing ink, wherein the antifoaming agent is non-silicone.

  Moreover, this invention relates to the said printing ink whose viscosity in 25 degreeC is 2-20 Pa.s.

  The present invention also relates to the above-mentioned printing ink for screen printing.

  The present invention also relates to a printed material having a printing layer printed with the above-mentioned printing ink on a substrate.

  The present invention also relates to the above-mentioned printed matter in which the substrate is a transparent substrate.

Further, the present invention relates to the above-mentioned printed matter, wherein L ^* is 10 or less, a ^* is 0 to 3 and b ^* is 0 to 7 measured from the side opposite to the side having the print layer.
(However, L ^* , a ^* and b ^* represent values in the L ^* a ^* b ^* color system specified in JIS Z8729.)

  Moreover, this invention relates to the said printed matter whose average transmittance | permeability in wavelength 380-780 nm is 5% or more measured from the surface on the opposite side to the surface which has a printing layer.

  According to the present invention, it has become possible to provide a printing ink and a printed matter which are excellent in temporal stability, leveling property, transferability, and can achieve both jet clarity and transparency with high blackness.

Hereinafter, although the present invention is explained in detail, it may be abbreviated as "printing ink" or "ink", but the printing ink is synonymous. Moreover, the thing of the film by which the printing ink is printed may be called a "printing layer", an "ink film", or an "ink layer", but it is synonymous.

  The printing ink of the present invention is a printing ink comprising carbon nanotubes having an average diameter of 5 to 30 nm and a binder resin, and the binder resin contains an acrylic resin having an acid value of 1 to 25 mg KOH / g. Printing ink. The carbon nanotube can be favorably dispersed by the binder resin containing the acrylic resin having the acid value.

The printing ink of the present invention preferably has a viscosity of 2 to 20 Pa · s at 25 ° C. Moreover, as for the thix index (TI) of the printing ink, TI in 25 degreeC is 1.1-1.9, and it is preferable that it is 1.4-1.7. TI is an index of the thixotropic property of the ink, and is represented by the following formula 1 as a ratio of viscosity at two different points of shear rate (rotational speed) of the ink. As the method of measurement, a rotary viscometer can be most simply used, and any type of measuring machine can be obtained. In addition, a viscosity means the measured value in 25 degreeC by JISZ8803.

(Formula 1) Thixotropic index (TI) = Xa / Xb

(In the formula, Xa refers to the viscosity at a low rotational speed with a rotary viscometer, and Xb refers to the viscosity at a higher rotational speed than Xa with a rotational viscometer.)

(carbon nanotube)

The carbon nanotubes used in the present invention are carbon nanotubes having an average diameter of 5 to 30 nm. Here, the average diameter refers to the average diameter of the portion corresponding to the circle in the cylindrical shape, and means the average value of the diameters of each of the ten arbitrary carbon nanotubes observed by a scanning transmission electron microscope. By using such a carbon nanotube, the jet blackness of the ink film and the transparency of the printing layer are improved. In addition, by using an acrylic resin having an acid value of 1 to 25 mg KOH / g, it is presumed that the carbon nanotubes will be in a good dispersed state in the printing ink, and a state close to the nanodispersion will be maintained.

A carbon nanotube is a cylindrically shaped compound in which a six-membered ring network structure (graphite layer) made of carbon is a single layer or a multilayer coaxial tube. The single-layer carbon nanotube (SWCNT) is referred to as a single-layer graphite layer, and the multi-walled carbon nanotube (MWCNT) is referred to as a single-layer carbon nanotube (SWCNT). As the carbon nanotubes used in the present invention, either a single-walled carbon nanotube or a multi-walled carbon nanotube may be selected and used for the control of coloring effect and jet-blackness, or may be used in combination. Among them, it is preferable to contain MWCNT.

The carbon nanotubes are preferably contained in an amount of 1 to 7% by mass, and more preferably 2 to 5% by mass, based on the total mass of the printing ink. By setting it as the said content rate, the printed matter which shows more favorable jet-blackness is obtained. Moreover, it is preferable to contain by 20-40 mass% in the total mass of ink solid content for printing. The solid content refers to the total mass of non-volatile components in the printing ink.

(Binder resin)
In the present specification, the binder resin refers to a resin that can function as a binder in printing ink, and is preferably a thermoplastic resin. Moreover, binder resin contains the acrylic resin of 1-25 mgKOH / g of acid values. The binder resin is preferably contained in an amount of 20 to 40% by mass, and more preferably 25 to 35% by mass, in the total mass of the ink. Moreover, it is preferable that 70-100 mass% of acrylic resin of an acid value 1-25 mgKOH / g is contained in the total mass of binder resin.

As binder resins other than acrylic resin with an acid value of 1 to 25 mg KOH / g, styrene resin, polyurethane resin, polyepoxy resin, polyester resin, rosin resin, styrene-acrylic resin, styrene-maleic resin, acrylic-urethane resin Dammar resin, vinyl chloride-vinyl acetate copolymer resin, polycarbonate resin, rosin modified maleic acid resin, rosin ester resin, terpene resin, acrylic resin having an acid value of 1 to 25 mg KOH / g, and other thermoplastic resins. These binder resins may be used in combination as long as the effects of the present invention are not impaired, and it is preferable to use less than 30% of the total mass of the binder resin.

(Acrylic resin with an acid value of 1 to 25 mg KOH / g)
In the present specification, the "acrylic resin" refers to a resin having an acrylic monomer as a main component in a structural unit. The "acrylic monomer" means a monomer having an acrylic group or a methacryloyl group, and "methacrylic and acrylic" may be collectively referred to as "(meth) acrylic". Also, "methacrylate and acrylate" may be collectively referred to as "(meth) acrylate".

The acrylic resin having an acid value of 1 to 25 mg KOH / g preferably has an acid value of 10 to 25 mg KOH / g, and is 10 to 20 mg KOH / g, from the viewpoint of improving the jet blackness of the ink film and the temporal stability of the printing ink. Is more preferred. As a method of giving an acid value to an acrylic resin, although it is easily obtained by copolymerizing acidic monomers, such as a carboxyl group-containing acrylic monomer, and another monomer, it is not limited to this. Examples of the acidic monomer include (meth) acrylic acid, maleic acid, maleic anhydride, phthalic acid, phthalic anhydride, monohydroxyethyl (meth) acrylate succinate, monohydroxyethyl (meth) acrylate phthalate, and hexahydrophthalic acid mono Hydroxyethyl (meth) acrylate, 2- (meth) acryloyloxyethyl acid phosphate and the like are preferable, and among them, (meth) acrylic acid is preferably used. In addition, an acid value says the measured value in JISK 0070 (1992).

  The glass transition temperature (hereinafter sometimes referred to as “Tg”) of the acrylic resin having an acid value of 1 to 25 mg KOH / g is preferably in the range of 50 to 110 ° C., preferably 60 to 110 ° C. More preferably, the temperature is 70 ° C to 100 ° C. This is because the blocking resistance of the printing layer made of the printing ink is improved. The glass transition temperature is a value measured by a differential scanning calorimeter (DSC).

The weight average molecular weight (Mw) of the acrylic resin having an acid value of 1 to 25 mg KOH / g is preferably 20,000 to 100,000, and more preferably 50,000 to 80,000. This is because the properties of the ink film are improved. In addition, a weight average molecular weight or a number average molecular weight says the converted value with respect to the polystyrene by the gel permeation chromatography (GPC) measurement which used tetrahydrofuran as a solvent.

An acrylic resin contains an acrylic monomer as a structural unit. Although the acrylic monomer which comprises an acrylic resin is listed below, it is not limited to these. In addition, an acrylic monomer may be used independently and may use 2 or more types together. Among the acrylic monomers listed below, the acrylic monomer preferably contains an alkyl methacrylate and / or an alkyl acrylate, and more preferably contains a methyl methacrylate. The content thereof is preferably 5 to 95% by mass in the total mass of the acrylic resin. The acrylic monomer can also contain a hydroxyl group-containing alkyl (meth) acrylate.

Preferably, at least one structural unit selected from the group consisting of methyl methacrylate, alkyl (meth) acrylate and (meth) acrylic acid is contained in an amount of 80 to 100% by mass based on the total mass of the acrylic resin.

  Examples of alkyl (meth) acrylates include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, pentyl (meth) acrylate and hexyl (meth) acrylate , (Meth) acrylic acid cyclohexyl, (meth) acrylic acid cyclopentyl, (meth) acrylic acid methyl cyclohexyl, (meth) acrylic acid bornyl, (meth) acrylic acid isobornyl, (meth) acrylic acid dicyclopentenyl, (meth) acrylic Dicyclopentanyl acid, 2-ethylhexyl (meth) acrylate, isooctyl (meth) acrylate, decyl (meth) acrylate, dodecyl (meth) acrylate, tetradecyl (meth) acrylate, hexadecyl (meth) acrylate, (Meth) acrylic acid octadesi And the like. Among these, the alkyl group preferably has 1 to 6 carbon atoms, and methyl (meth) acrylate is more preferable from the viewpoint of easily obtaining good adhesion to the substrate.

  The acrylic monomer may contain a hydroxyl group-containing alkyl (meth) acrylate, for example, 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, 8-hydroxyoctyl (meth) acrylate, etc. (Meth) acrylic acid hydroxyalkyl ester, glycol mono (meth) acrylate such as polyethylene glycol mono (meth) acrylate, polypropylene glycol mono (meth) acrylate, 1,4-cyclohexanedimethanol mono (meth) acrylate, cap Lactone-modified (meth) acrylate, and hydroxyethyl acrylamide. Among these, 2-hydroxyethyl (meth) acrylate and 4-hydroxybutyl (meth) acrylate are preferable.

(Pigment)
In the printing ink of the present invention, an organic pigment, an inorganic pigment, an extender pigment and the like which are usually used other than the above-mentioned carbon nanotube may be used in combination. As the organic pigment, azo type, phthalocyanine type, anthraquinone type, perylene type, perinone type, perinone type, quinacridone type, thioindigo type, dioxazine type, isoindolinone type, quinophthalone type, azomethine azo type, diketopyrrolopyrrole type, isoindoline type etc. Pigments are preferred but not limited thereto. C. described in Color Index. I pigment can be used suitably. Examples of the inorganic pigment include carbon black, aluminum paste, mica (mica), bronze powder, chromium vermilion, yellow lead, cadmium yellow, cadmium red, ultramarine blue, bitumen, red iron oxide, yellow iron oxide, iron black and the like. As the extender pigment, silica, alumina, talc, calcium carbonate, precipitated barium and the like are preferably used.

(Organic solvent)
The printing ink of the present invention preferably contains an organic solvent. As an organic solvent, it is preferable that a boiling point is 50-250 degreeC, and it is more preferable that it is 100 degreeC-220 degreeC. Examples of the organic solvent include glycol ether type organic solvents, ester type organic solvents, ketone type organic solvents, aliphatic type organic solvents, aromatic type organic solvents, alcohol type organic solvents, ether type organic solvents, if necessary Two or more of these can be mixed and used.

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, propylene glycol monobutyl ether.

Examples of ester 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. Tart, diethylene glycol monobutyl ether acetate, propylene carbonate and the like.

Examples of ketone-based organic solvents include acetone, methyl ethyl ketone, methyl propyl ketone, diethyl ketone, methyl n-butyl ketone, methyl isobutyl ketone, dipropyl ketone, diisobutyl ketone, diisobutyl ketone, methyl amyl ketone, acetonyl acetone, isophorone, cyclohexanone, methyl cyclohexanone, etc. It can be mentioned.

  Examples of the aliphatic organic solvent include normal paraffin solvents, isoparaffin solvents, cycloparaffin solvents and the like.

  As an aromatic organic solvent, for example, toluene, xylene, ethylbenzene, naphthalene, tetralin, solvent naphtha, and as a solvent rich in aromatics, swazole (Cosmo Petroleum Co., Ltd., Maruzen Petrochemical Co., Ltd.) Solvesso (Exxon Mobil Co.) And Cactus Fine (manufactured by Japan Energy).

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

  Examples of ether-based organic solvents include cyclic ethers such as tetrahydrofuran and 1,3-dioxolane. Other liquid media include dimethyl carbonate, ethyl methyl carbonate and di-n-butyl carbonate.

(Defoamer)
The printing ink of the present invention preferably contains an antifoaming agent. The content is preferably 0.1 to 2% by mass in the total mass of the printing ink. As a compound which comprises an antifoamer, an acrylic resin, vinyl ether resin, butadiene resin, a silicone resin, a fluorine resin, and those modified resin are mentioned (however, the said binder resin is not included). The antifoaming agent is preferably a non-silicone resin, and preferably contains at least one resin selected from an acrylic resin, a vinyl ether resin, and a butadiene resin.
For example, as such an antifoamer marketed, BYK series (made by BIC Chemie Japan company) Floren series (made by Kyoeisha Chemical company) etc. are mentioned.

(Leveling agent)
The printing ink of the present invention preferably further contains a leveling agent. The content is preferably 0.1 to 1% by mass in the total mass of the printing ink. As a compound which comprises a leveling agent, it is preferable that they are an acrylic resin and / or a silicone resin (however, the said binder resin is not included). For example, as such a leveling agent marketed, Polyflow series (made by Kyoeisha Chemical Co., Ltd.) etc. are mentioned. These may be used alone or in combination of two or more.

(Other additives)
In addition, additives such as dispersant, wet penetration agent, anti-skinning agent, UV absorber, antioxidant, cross-linking agent, preservative, anti-mold agent, viscosity modifier, pH adjuster, etc. It can mix | blend suitably in the range which does not inhibit the objective of invention. Among these, it is preferable to use a dispersant. This is because the sense of jet blackness of the printed matter is improved. As a dispersing agent, an acidic dispersing agent is preferable.

(Production of printing ink)
The printing ink of the present invention can be appropriately prepared by a known dispersing method. For example, a binder resin, carbon nanotubes, an organic solvent and an additive may be mixed in a necessary amount, stirred well with a stirrer or the like, and then manufactured using a three-roll, disperser such as a paint shaker, attritor or sand mill. is there.

(Base material)
The substrate used to form the printed matter in the present invention is not particularly limited, and inorganic substrates such as glass, polyester substrates such as polyethylene terephthalate, polyethylene, polypropylene, ethylene-vinyl acetate and other polyolefin substrates And nylon substrates such as polyamide, acrylic substrates, polyvinylidene chloride substrates, polycarbonate substrates, polyurethane substrates, and resin substrates such as epoxy substrates. Moreover, the vapor deposition base material which vapor-deposited inorganic compounds, such as a silica, an alumina, and aluminum, on the said base material can also be used, and the vapor deposition process surface may be further coat-treated by polyvinyl alcohol etc. In addition, corona treatment, frame treatment, or stretching treatment may be performed. Among the above, it is preferable that it is a transparent base material.

(Printed matter)
The printed matter of the present invention refers to a printed matter formed of a printing ink on a substrate by an arbitrary printing method. The printing method may, for example, be screen printing, offset printing, gravure printing, flexo printing, etc. Among them, screen printing is preferred.
The printed matter has an L ^* value of 10 or less, an a ^* value of 0 to 3 and a b ^* value of 0 to 7 measured from the side opposite to the side having the printing layer printed on the substrate. Is preferred. L ^* , a ^* and b ^* represent numerical values measured in accordance with JIS Z8729. In L ^* a ^* b ^* , L ^* represents the lightness of the color as a diffuse color in the black direction when the value is 0 and as the white color when the value is 100. a ^* b ^* represents the chromaticity, a ^* is the hue between red and green, and in the case of a negative value is the hue in the green direction, and the positive value represents the hue in the red direction. b ^* is a hue between yellow and blue, with a negative value representing a blue hue and a positive value representing a yellow hue. L ^* a ^* b ^* is expressed as three-dimensional coordinates. In addition, L ^* a ^* b ^* value says the measured value in reflection.
Moreover, with a transmittance | permeability, a transmission spectrum is measured in the range of wavelength 300-1500 nm from the surface on the opposite side of the side which has a printing layer in the said printed matter, The weighted average value of each transmittance | permeability of wavelength 380 nm-780 nm of visible region It is a value calculated by finding, and it refers to the measured value in the transmission spectrum. In addition, a weighted average value means the calculated value by JISR3106 (1998).

  Hereinafter, the present invention will be specifically described as an example, but the present invention is not limited at all by the following example. In the present invention, unless otherwise specified, "part" represents "part by mass", and "%" represents "% by mass", respectively.

(Average diameter of carbon nanotubes)
In an observation photograph by a scanning transmission electron microscope (HD-2700 manufactured by Hitachi High-Technologies Corporation), arbitrary 10 carbon nanotubes are selected, the diameters of the respective carbon nanotubes are measured, and the average value is obtained. did.

(Weight average molecular weight)
The weight average molecular weight was determined by GPC (gel permeation chromatography) method. The molecular weight distribution was measured using “Shodex GPC System 21” manufactured by Showa Denko K. K., and the molecular weight in terms of polystyrene was determined. The measurement conditions are shown below.
Column: The following multiple columns are connected in series and used.
Tosoh Corporation TSKgel Super AW 2500,
Tosoh Corporation TSKgel SuperAW 3000,
Tosoh Corporation TSKgel SuperAW 4000,
Tosoh Corporation TSKgel guardcolumn SuperAWH
Detector: RI (differential refractometer),
Measurement conditions: Column temperature 40 ° C.
Eluent: tetrahydrofuran flow rate: 1.0 mL / min

(Acid number)
It measured according to the method as described in JISK 0070 (1992).

(Glass transition temperature (Tg))
The glass transition temperature (Tg) was determined by DSC (differential scanning calorimetry measurement). The measuring instrument used is DSC8231 manufactured by Rigaku Corporation, measurement temperature range-50 to 250 ° C, temperature rising rate 10 ° C / min, inflection point of baseline change based on glass transition in DSC curve to glass transition temperature And

(Viscosity and Thix index (TI))
Measured according to JIS Z 8803 (2011) at 25 ° C. using a single cylindrical rotational viscometer. The thixotropic index was calculated as the ratio of the viscosity at 6 rpm and 60 rpm by the above (formula 1).

(L ^* a ^* b ^* value)
It measured according to JISZ8781-4 (2013) from the surface on the opposite side of the surface which has a printing layer of printed matter. In addition, the color difference meter (NIPPON DENSHOKU company make, SpectroColorMeterSE2000) was used for the measurement. In addition, a measured value says the measured value by reflection.

(Average transmittance)
Using a UV-visible near-infrared spectrophotometer (manufactured by Hitachi, Ltd., UV-3500), the transmission spectrum of the printed matter is measured in the wavelength range of 300 to 1500 nm from the side opposite to the side having the printing layer. It calculated by calculating | requiring the weighted average value of each transmittance | permeability of wavelength 380nm-780nm.

(Example 1) [Preparation of printing ink S1]
3.5 parts of NC-7000 (Nanosil Co., Ltd., average diameter 9.5 nm, MWCNT) as a carbon nanotube, an acrylic resin having an acid value of 7 mg KOH / g as a binder resin (Dianal BR-116, methyl methacrylate acrylic resin, weight average Molecular weight 45,000, Glass transition temperature 50 ° C Acid value 7.0 mg KOH / g 27.5 parts by Mitsubishi Chemical Co., Ltd., BYK-057 (Butadiene copolymer, manufactured by Byk Chemie-Jappan Co., Ltd.) 1 as a non-silicone antifoaming agent .5 parts, polyflow NO. 7 (acrylic resin, manufactured by Kyoeisha Chemical Co., Ltd.) 0.5 parts, 20 parts of butyl cellosolve as a solvent, and 47 parts of diacetone alcohol are uniformly mixed using a mixer rotary stirrer, and then a 3-roll disperser is subjected to 2 passes Thus, a printing ink (S1) was prepared. The viscosity of the printing ink (S1) was 2.4 Pa · s.

(Examples 2 to 12 and Comparative Examples 1 to 4) [Preparation of Printing Inks S2 to S10, T1 to T4]
Printing inks were prepared in the same manner as in Example 1 except that the materials and proportions described in Table 1 were changed. The abbreviations in the table are shown below. Also, the numerical values in the table indicate "parts" unless otherwise noted, and the blanks indicate that they are not used.

<Carbon nanotube>
Flotube 9000: Carbon nanotubes, manufactured by CNano, average diameter 12.5 nm, MWCNT
SMW 210: carbon nanotubes, manufactured by SouthWest NanoTechnologies, average diameter 10 nm, MWCNT
<Carbon black>
Mitsubishi Carbon MA-100: Carbon black, manufactured by Mitsubishi Chemical Corporation, primary particle size 24 nm

<Acrylic resin>
Dianal BR-77: acid value 18.5 mg KOH / g, methyl methacrylate / butyl methacrylate based acrylic resin weight average molecular weight 65,000, glass transition temperature 80 ° C., manufactured by Mitsubishi Chemical Co., Ltd. dinal BR-87: acid value 10.5 mg KOH / G, methyl methacrylate / alkyl methacrylate acrylic resin weight average molecular weight 25,000, glass transition temperature 105 ° C, Mitsubishi Chemical Co., Ltd. dinal MB-2389: acid value 2.3 mg KOH / g, methyl methacrylate acrylic resin weight average molecular weight 30,000, glass transition temperature 90 ° C., Paraloid B66 manufactured by Mitsubishi Chemical Co., Ltd .: acid value 3 mg KOH / g, methyl methacrylate acrylic resin weight average molecular weight 70,000, glass transition temperature 50 ° C., Dianal manufactured by Rohm and Haas BR-110: acid value 0.0 mg KOH / g, acrylic resin weight average molecular weight 72,000, glass transition temperature 90 ° C.
<Polyester resin>
Byron 200: acid value 2 mg KOH / g, amorphous polyester resin, weight average molecular weight 30,000, glass transition temperature 67 ° C., Toyobo Co., Ltd. <leveling agent>
KF-96-1000CS: Silicone resin, Shin-Etsu Chemical Co., Ltd.

(Example 13) [Printing with printing ink S1]
Using a transparent base material made of polycarbonate resin (Panalite PC2151 made by Teijin Ltd. 300 μm film thickness) as a base material, the printing ink S1 is printed on the base material as a screen printing plate (L-SCREEN manufactured by NBC Meshtec Co., Ltd.) , 140-030 / 355PW) was used to print a pattern to produce a printed matter.

(Examples 13 to 24 and Comparative Examples 5 to 8) [Printing with Printing Inks S2 to S12, T1 to T4]
Printed materials were prepared in the same manner as in Example 1, except that the printing ink described in Table 2 was changed to the printing ink S1 used in Example 1.

(Evaluation of printing ink and its printed matter)
The following evaluation was performed about the printing ink and printed matter obtained by the said Example and comparative example. The evaluation results are shown in Table 2.

(Stability over time)
The printing inks obtained in Examples 1 to 12 and Comparative Examples 1 to 4 were maintained at 40 ° C. for 5 days. The change in viscosity value before and after holding was evaluated. The criteria for the evaluation results were as follows.
A (excellent): The change in viscosity is less than 10%.
B (Good): Viscosity change of 10% or more and less than 20%.
C (Defective): Viscosity change of 20% or more.
Industrially available levels are A and B.

(Evaluation of leveling ability)
Evaluation was performed using the printed matter obtained in Examples 13-24 and Comparative Examples 5-8. The criteria for the evaluation results were as follows. "Print unevenness" means a state in which the shade of color of the print layer is uneven.
A (excellent): Less than 5% of the area in the pattern has uneven printing.
B (Good): The area of 5% or more and less than 20% in the pattern has printing unevenness.
C (defect): 20% or more of the area in the pattern has printing unevenness.
Industrially available levels are A and B.

(Evaluation of metastasis)
Evaluation was performed using the printing ink obtained in Examples 1-12 and Comparative Examples 1-4. In the following evaluation, the transfer rate refers to the calculated weight of the ink mass transferred per unit area in one printing. The criteria for the evaluation results were as follows.
A (excellent): The transfer rate of the printing ink is 90% by mass or more.
B (Good): The transfer ratio of the printing ink is 80% by mass or more and less than 90% by mass.
C (defect): The transfer rate of the printing ink is less than 80% by mass.
Industrially available levels are A and B.

(Evaluation of jet blackness)
Evaluation was performed using the printed matter obtained in Examples 11 to 20 and Comparative Examples 5 to 8. The criteria for the evaluation results were as follows.
A (excellent): L ^* is 8 or less, a ^* is 0 to 3, and b ^* is 0 to 7.
B (good): L ^* is more than 8 and 10 or less, a ^* is 0 to 3 and b ^* is 0 to 7.
C (defect): L ^* is more than 10, a ^* is 4 or more and less than 0 or more, or b ^* is less than 0 or more than 7;
Industrially available levels are A and B.

(Evaluation of permeability)
Evaluation was performed using the printed matter obtained in Examples 13-24 and Comparative Examples 5-8. The criteria for the evaluation results are as follows.
A (excellent): The average transmittance of the printed matter is 10% or more.
B (Good): Average transmittance of printed matter is 5% or more and less than 10%.
C (defective): the average transmittance of the printed matter is less than 5%.
Industrially available levels are A and B.

The present invention has been made to solve the above-mentioned problems, and it has become possible to provide a printing ink and a printed matter which are excellent in jet clarity, leveling property, transferability and transparency.

As a result of earnest research, the present inventors have found that the above problems can be solved, and have completed the present invention. That is, the present invention is a screen printing ink comprising carbon nanotubes having an average diameter of 5 to 30 nm, a binder resin, and an organic solvent, and having an acid value of 1 to 25 mg KOH / g in the total binder resin mass. Screen printing ink having a glass transition temperature of 60 to 110 ° C., 70 to 100% by mass of an acrylic resin having a structural unit consisting of methyl methacrylate, and having a thixotropic index at 25 ° C. of 1.1 to 1.9 About.

Moreover, this invention relates to the said ink for screen printings whose weight average molecular weight of the said acrylic resin is 20,000-100,000 .
Moreover, this invention relates to the said ink for screen printings which the said organic solvent contains the organic solvent whose boiling point is 50-250 degreeC.

The present invention further relates to the above screen printing ink comprising 0.1 to 2% by mass of an antifoaming agent.

Moreover, this invention relates to the said ink for screen printings whose said antifoamer is non-silicone type.

Moreover, this invention relates to the said ink for screen printing whose viscosity in 25 degreeC is 2-20 Pa.s.

The present invention also relates to the printing screen ink for screen printing.

The present invention also relates to a printed material having a printing layer printed with the above screen printing ink on a substrate.

(Examples 2 to 12 and Comparative Examples 1 to 4) [Preparation of Printing Inks S2 to S10, T1 to T4]
Printing inks were prepared in the same manner as in Example 1 except that the materials and proportions described in Table 1 were changed. The abbreviations in the table are shown below. Also, the numerical values in the table indicate "parts" unless otherwise noted, and the blanks indicate that they are not used.
In the present specification, the examples other than the examples 2 to 11 (inks S2 to S11) and the examples 14 to 23 of the printed matter using the same are reference examples.

Claims (10)

A printing ink comprising carbon nanotubes having an average diameter of 5 to 30 nm and a binder resin, wherein the binder resin comprises an acrylic resin having an acid value of 1 to 25 mg KOH / g and has a thixotropic index at 25 ° C of 1. Printing ink which is 1 to 1.9. The printing ink according to claim 1, wherein the glass transition temperature of the acrylic resin is 60 to 110 ° C.   The printing ink according to claim 1, further comprising 0.1 to 2% by mass of an antifoaming agent. The printing ink according to any one of claims 1 to 3, wherein the antifoaming agent is non-silicone. The viscosity at 25 degreeC is 2-20 Pa.s, The ink for printing in any one of Claims 1-4.   The printing ink according to any one of claims 1 to 5, which is for screen printing.   The printed matter which has a printing layer printed by the ink for printing in any one of Claims 1-6 on a base material.   The printed matter according to claim 7, wherein the substrate is a transparent substrate. The printed matter according to claim 7 or 8, wherein L ^* is 10 or less, a ^* is 0 to 3 and b ^* is 0 to 7 measured from the side opposite to the side having the print layer.
(However, L ^* , a ^* and b ^* represent values in the L ^* a ^* b ^* color system specified in JIS Z8729.)   The printed matter according to any one of claims 7 to 9, wherein the average transmittance at a wavelength of 380 to 780 nm is 5% or more, which is measured from the side opposite to the side having the printing layer.