JP7139712B2 - gravure or flexo ink - Google Patents

Description

The present invention relates to gravure or flexographic inks and their prints.

More specifically, it relates to a gravure or flexo ink containing a polyurethane resin having a biomass component as a structural unit.

In recent years, biomass-derived materials have been attracting attention as alternative materials against the depletion of petrochemical resources. Among them, sebacic acid and succinic acid, which are derived from biomass, are promising resin raw materials because polyester compounds thereof can be obtained. However, most conventional petroleum-derived polyester compounds are derived from adipic acid, which does not have a significant performance advantage over adipic acid-based polyester resins. becomes higher.

Polyester compounds include, for example, polyester polyols, which are often used as raw materials for producing polyurethane resins. Polyurethane resins are useful as binder resins for gravure or flexographic printing inks, and have been favorably used because of their flexibility and good adhesion (Patent Documents 1 and 2). On the other hand, the gravure or flexographic inks are also required to be environmentally friendly by using biomass.

Gravure or flexo ink is an industrially important printing technology because it has high productivity due to the characteristics of the printing method, high-speed printing and winding method, and can express high-definition patterns. Gravure or flexographic inks have relatively low ink viscosity, and because the printing machine is large, they are greatly affected by the temperature and humidity factors of the printing environment. In addition, there are cases where problems occur due to factors such as the temperature in which the printed matter and laminated laminate are placed.

In particular, when the room temperature is low in the printing environment, problems such as plate fogging in gravure printing and plate entanglement in flexographic printing tend to occur. In addition, in a laminate laminate, since the polyurethane resin becomes hard at low temperatures, the laminate strength tends to decrease, and the amount of residual solvent in the printed matter tends to increase. Therefore, it is regarded as a problem in winter in Japan and in areas where the climate is low.

JP 2016-150941 A JP 2018-44047 A JP 2018-62642 A

An object of the present invention is to provide a gravure or flexographic ink containing a biomass-derived polyurethane resin for a laminate having good low-temperature printability and good low-temperature lamination strength.

As a result of earnest studies, the present inventors have found that the above problems can be solved by using the gravure or flexographic ink described below, and have completed the present invention.

That is, the present invention
A gravure or flexographic ink containing a polyurethane resin (A) as a binder resin and an organic solvent,
The polyurethane resin (A) contains a structural unit derived from a polyester polyol consisting of a dibasic acid containing azelaic acid and a diol, and contains 10% by mass or more of the structural unit derived from azelaic acid in the total mass of the polyurethane resin (A). for gravure or flexographic inks.

The present invention relates to the gravure or flexo ink, wherein the polyurethane resin (A) further contains structural units derived from polyether polyol.

The present invention relates to the above gravure or flexographic ink, wherein the binder resin further contains at least one resin (B) selected from the group consisting of vinyl chloride copolymer resins, cellulose resins and rosin resins.

The present invention relates to the above gravure or flexo ink, wherein the binder resin contains the polyurethane resin (A) and the resin (B) at a mass ratio (A):(B) of 95:5 to 30:70.

The present invention relates to a printed matter having a printing layer made of the gravure or flexo ink on a substrate 1 .

The present invention relates to a laminate having a substrate 2 on the printed layer of the printed matter.
related.

INDUSTRIAL APPLICABILITY According to the present invention, it is possible to provide a gravure or flexographic ink containing a biomass-derived polyurethane resin for a laminate having good low-temperature printability and good low-temperature lamination strength.

Embodiments of the present invention will be described in detail below, but the description of the constituent elements described below is an example (representative example) of embodiments of the present invention, and the present invention does not exceed the gist thereof. Content is not limited.

The gravure or flexo ink of the present invention will be described. Gravure or flexographic ink may be simply abbreviated as "ink" below, but is synonymous with gravure or flexographic ink. Further, the printing layer made of gravure or flexo ink is sometimes referred to as "printing layer", "ink layer" or "ink film", but is synonymous with the printing layer made of gravure or flexo ink.

The present invention is a gravure or flexo ink containing a polyurethane resin (A) as a binder resin and an organic solvent,
The total weight of the polyurethane (A) contains a structural unit derived from a polyester polyol composed of a dibasic acid containing azelaic acid and a diol, and the total weight of the polyurethane resin (A) contains 10% by weight of the structural unit derived from azelaic acid. gravure or flexographic ink containing the above.
Azelaic acid is a dibasic acid obtained from fatty acids derived from vegetable and animal oils and has characteristic properties. Dibasic acids have an even and odd number of carbon atoms between carboxyl groups, which appears in the melting point and the like. For example, the melting point of azelaine, which has 7 carbon atoms between carboxyl groups, is 106° C., while the melting point of suberic acid, which has 6 carbon atoms between carboxyl groups, is 144° C., and zebacine, which has 8 carbon atoms between carboxyl groups. The melting point of the acid is 135°C. Therefore, a polyester polyol composed of azelaic acid and a diol is flexible and tough, and it is possible to obtain a polyurethane resin particularly excellent in low-temperature properties. Furthermore, when used in combination with a resin (B) described later, it exhibits better low-temperature properties as a gravure or flexographic ink. Such characteristics tend to be difficult to obtain when the azelaic acid-derived structure is not contained.

<Binder resin>
As used herein, the binder resin refers to a binder resin in gravure or flexo ink, and contains the following polyurethane resin (A). The binder resin is preferably contained in an amount of 2 to 15% by mass in the total mass of the ink, and the polyurethane resin is preferably contained in an amount of 40% by mass or more in the total mass of the binder resin.

<Polyurethane resin (A)>
The polyurethane resin (A) used in the present invention contains a structural unit derived from a polyester polyol consisting of a dibasic acid containing azelaic acid and a diol, and 10 structural units derived from azelaic acid in the total mass of the polyurethane resin (A). It contains more than mass %. The structural unit is represented by the following chemical formula (1), is a structural unit forming an ester structure, and may be contained in a single polyester polyol, or may be contained in a polyester polyol in which several types are used in combination. can be anything.

化学式（１）で表される構造の含有量としてはポリウレタン樹脂（Ａ）中に１５～４５質量％であることが好ましく２０～４０質量％がより好ましく、２５～４０質量％が更に好ましい。下記樹脂（Ｂ）との組み合わせで低温での印刷適性および低温でのラミネート強度等が向上するためである。なお、化学式（１）で表されるエステル構造の含有量は、合成時の配合量より算出できる。 (Chemical formula (1))

The content of the structure represented by the chemical formula (1) is preferably 15 to 45% by mass, more preferably 20 to 40% by mass, and even more preferably 25 to 40% by mass in the polyurethane resin (A). This is because the combination with the resin (B) described below improves the printability at low temperatures and the laminate strength at low temperatures. The content of the ester structure represented by the chemical formula (1) can be calculated from the compounding amount during synthesis.

Further, the polyurethane resin (A) preferably contains 15 to 75% by mass, more preferably 20 to 75% by mass, of the structural unit derived from the polyester polyol in the total mass of the polyurethane resin (A), and 30 to 75% by mass. It is more preferable to contain 60% by mass. The polyurethane resin (A) preferably further has a hydroxyl value, preferably 1 to 30 mgKOH/g, more preferably 2 to 20 mgKOH/g. This is for producing affinity with the organic solvent and affinity with the resin (B), which will be described later.
Further, it preferably has an amine value, preferably 0.5 to 15 mgKOH/g, more preferably 1 to 10 mgKOH/g.

The polyurethane resin (A) is preferably a polyurethane resin (A) that is a reaction product of a polyisocyanate and a polyol containing a polyester polyol. It is more preferably a polyurethane resin (A) chain-extended.

<Polyester Polyol Consisting of Dibasic Acid Containing Azelaic Acid and Diol>
The polyester polyol preferably has a number average molecular weight of 500 to 5,000. The number average molecular weight is obtained by the following formula (1), and the valence is the average number of hydroxyl groups in one polyol molecule. Refers to mg of potassium hydroxide required for neutralization.
Formula (1) Number average molecular weight = 1000 × 56.1 × valence of hydroxyl group / hydroxyl value ), but preferably contains 50% by mass or more of azelaic acid, more preferably 60% by mass or more, and 70% by mass or more in the total mass of dibasic acids constituting the polyester polyol more preferably. Other dibasic acids are preferably at least one dibasic acid selected from adipic acid, sebacic acid, succinic acid and dimer acid.

(diol)
Examples of diols constituting the polyester polyol include ethylene glycol, triethylene glycol, propylene glycol, 1,3-propanediol, 1,4-butanediol, 1,3-butanediol, 1,6-hexanediol, 1,8 - octanediol, 1,9-nonanediol, neopentyl glycol, 3-methyl-1,5-pentanediol, 2-methyl-1,3-propanediol, 3,3,5-trimethylpentanediol, 1,12 - Octadecanediol, 1,2-alkanediol, 1,3-alkanediol, dimer diol, hydrogenated dimer diol, etc., and physical properties such as printability at low temperature and laminate strength at low temperature are easily obtained, so branched A diol is preferred. A branched diol is a diol in which at least one of the hydrogen atoms of the alkylene group of the alkylene diol is substituted with an alkyl group. Specifically, at least one selected from propylene glycol, 1,3-propanediol, 1,4-butanediol, neopentyl glycol, 3-methyl-1,3-propanediol, and 3-methyl-1,5-pentanediol A kind of diol is preferred.

In the following description, "other polyester polyols" refer to polyester polyols that do not contain polyester structural units composed of azelaic acid and diol.

<Other polyester polyols>
A polyester polyol may be used in combination with a polyester polyol other than the polyester polyol composed of azelaic acid and a diol. Other polyester polyols are preferably condensates of dibasic acids other than azelaic acid and diols, and specific embodiments are shown below.
Other dibasic acids constituting the polyester polyol are preferably at least one or more of adipic acid, sebacic acid, succinic acid, glutaric acid, pimelic acid and suberic acid. Further, examples of the diol include those similar to the diols described above. The number average molecular weight is a value calculated from the above formula (1), and is preferably 500 to 5,000.

<Polyether polyol>
Polyether polyols are preferably used for the polyurethane resin (A), and examples thereof include polyethylene glycol, polypropylene glycol, polytetramethylene glycol, polytrimethylene glycol, and copolymers thereof. The number average molecular weight is preferably 500-5000. The mass ratio of the polyester polyol (including other polyester polyols) and the polyether polyol (polyester polyol:polyether polyol) is preferably 60:40 to 95:5, preferably 70:30 to 95:5. more preferred. It is preferably contained in an amount of 40 to 5% by mass in the total mass of the polyurethane resin. It is more preferable to contain 30 to 10% by mass.

<Other polyols>
Polyurethane resin (A) can use polyol other than the above-mentioned polyol. Preferred embodiments are shown below. The polyol content is preferably 15% by mass or less, more preferably 10% by mass or less, and even more preferably 6% by mass or less, in the total mass of the polyurethane resin. As applicable polyols, diols having a molecular weight of 200 or less are preferable, and ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,6-hexanediol, 1,8-octanediol, 1,9- linear diols such as nonanediol, 1,2-propanediol, neopentyl glycol, 3-methyl-1,5-pentanediol, 2,4-diethyl-1,5-pentanediol, butylethylpropanediol, Examples include branched diols such as methylnonanediol, alicyclic diols such as cyclohexanedimethanol and cyclohexanediol, and a plurality of diols may be used in combination. Among them, an aliphatic diol having an alkyl group having 1 to 6 carbon atoms as a substituent is preferable because it improves the adhesiveness to the substrate and improves the solubility of the polyurethane, thereby improving the printability. More specifically, 3-methyl-1,5-pentanediol, 2,4-diethyl-1,5-pentanediol, butylethylpropanediol, 2-methyl-1,3-propanediol, and neopentyl glycol are preferred. used.

The above polyisocyanate preferably contains at least one diisocyanate selected from aromatic diisocyanates, aliphatic diisocyanates, and alicyclic diisocyanates. Such diisocyanates are, for example, 1,5-naphthylene diisocyanate, 4,4′-diphenylmethane diisocyanate, 4,4′-diphenyldimethylmethane diisocyanate, 4,4′-dibenzyl isocyanate, dialkyldiphenylmethane diisocyanate, tetraalkyldiphenylmethane diisocyanate, 1 ,3-phenylene diisocyanate, 1,4-phenylene diisocyanate, tolylene diisocyanate, butane-1,4-diisocyanate, hexamethylene diisocyanate, isopropylene diisocyanate, methylene diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, 2,4 ,4-trimethylhexamethylene diisocyanate, cyclohexane-1,4-diisocyanate, xylylene diisocyanate, isophorone diisocyanate, lysine diisocyanate, dicyclohexylmethane-4,4'-diisocyanate, 1,3-bis(isocyanatomethyl)cyclohexane, methylcyclohexane Typical examples include diisocyanate, m-tetramethylxylylene diisocyanate, and dimer diisocyanate obtained by converting the carboxyl group of dimer acid to an isocyanate group. These may be trimers to form an isocyanurate ring structure. These polyisocyanate species can be used alone or in combination of two or more.

The polyamines above react with isocyanate groups to form urea bonds, and preferred examples include ethylenediamine, propylenediamine, hexamethylenediamine, isophoronediamine, and dicyclohexylmethane-4,4'-diamine.
In addition, 2-hydroxyethylethylenediamine, 2-hydroxyethylpropylenediamine, di-2-hydroxyethylethylenediamine, di-2-hydroxyethylenediamine, di-2-hydroxyethylpropylenediamine, 2-hydroxypyropyrethylenediamine, di-2- It is also preferable to use amines having a hydroxyl group in the molecule, such as hydroxypypropylethylenediamine and di-2-hydroxypropylethylenediamine. These organic diamines can be used singly or in combination of two or more, and are preferred because they react very quickly with amino groups in the reaction with isocyanate groups, so that hydroxyl groups can be contained in the polyurethane resin (A).
Among them, isophoronediamine and/or 2-hydroxyethylethylenediamine are preferred. In addition, diethylenetriamine, iminobispropylamine: (IBPA, 3,3′-diaminodipropylamine), N-(3-aminopropyl)butane-1,4-diamine: (spermidine), 6,6-iminodihexylamine , 3,7-diazanonane-1,9-diamine, N,N'-bis(3-aminopropyl)ethylenediamine, and other polyfunctional amines having 3 or more amino groups can be used in combination with the above organic diamines.

The production of the polyurethane resin (A) used in the present invention is not particularly limited. Production methods described in publications and the like can be used as appropriate.

<Resin (B)>
In addition to the polyurethane resin (A), it is preferable to contain at least one resin (B) selected from vinyl chloride copolymer resins, cellulose resins and rosin resins. This is because, in addition to the flexibility and low-temperature properties of the polyurethane resin (A), the toughness of the resin (B) provides the strength and cohesion of the ink film, the printability at low temperatures, and the laminate strength. The content of polyurethane resin (A):resin (B) is preferably 95:5 to 30:70. The total content of the polyurethane resin (A) and the resin (B) is preferably 70 to 100% by mass, more preferably 85 to 100% by mass, in the total mass of the binder resin.

<Vinyl chloride copolymer resin>
A vinyl chloride copolymer resin is a resin containing vinyl chloride as a main component (50% by mass or more in the total mass of the resin), and for example, vinyl chloride-vinyl acetate copolymer resin, vinyl chloride-acrylic copolymer resin, etc. are suitable. mentioned.

(vinyl chloride-vinyl acetate copolymer resin)
A vinyl chloride-vinyl acetate copolymer resin is a resin obtained by copolymerizing vinyl chloride and vinyl acetate. Preferred embodiments are shown below.
As for the molecular weight, a weight average molecular weight of 5,000 to 70,000 is preferable, and 5,000 to 50,000 is more preferable. The structure derived from the vinyl acetate monomer in 100% by mass of the solid content of the vinyl chloride-vinyl acetate copolymer resin is preferably 1 to 30% by mass, and the structure derived from the vinyl chloride monomer is preferably 70 to 95% by mass. . In order to obtain low-temperature stability together with the polyurethane resin (A), the vinyl chloride-vinyl acetate copolymer resin preferably has a hydroxyl value of 20 to 200 mgKOH/g. Also, the glass transition temperature is preferably 60°C to 80°C.
The mass ratio of the polyurethane resin (A) to the vinyl chloride-vinyl acetate copolymer resin (polyurethane resin (A): vinyl chloride-vinyl acetate copolymer resin) is preferably 95:5 to 30:70, preferably 90:10. ~40:60 is more preferred. This is because the ink has good stability over time and good printability even under low temperature conditions, and also has good adhesion to the substrate, physical properties of the film, laminate strength, and the like.

<Cellulose resin>
The cellulosic resin refers to a fibrous carbon-based resin that is soluble in organic solvents. Preferred embodiments are shown below.
The cellulose resin preferably has a weight average molecular weight of 5,000 to 100,000, more preferably 10,000 to 70,000. Further, those having a glass transition temperature of 100° C. to 160° C. are preferable. Examples of the cellulose resin include nitrocellulose, cellulose acetate alkylates such as cellulose acetate propionate and cellulose acetate butyrate, and alkyl celluloses such as hydroxyalkyl cellulose and carboxyalkyl cellulose. Examples include methyl group, ethyl group, propyl group, isopropyl group, butyl group, isobutyl group, pentyl group, hexyl group and the like, and the alkyl group may further have a substituent. Among them, cellulose acetate propionate, cellulose acetate butyrate, and nitrocellulose are preferred.
The nitrogen content of nitrocellulose is preferably 10 to 13% by mass. This is because the ink has good stability over time and good printability even under low temperature conditions, and also has good adhesion to the substrate, physical properties of the film, laminate strength, and the like.

<Rosin resin>
The rosin resin used in the present invention is one having a structural unit derived from rosin acid (abietic acid, neoabietic acid, parastric acid, pimaric acid, isopimaric acid, dehydroabietic acid, etc.) as a main component (50% by mass or more). Say. The rosin acid or rosin resin may be hydrogenated. The acid value of the rosin resin is preferably 150 mgKOH/g or less, preferably 100 mgKOH/g or less, more preferably 50 mgKOH/g or less. The softening point is preferably 60-180°C. More preferably, the softening point is 70 to 150°C. Examples of types of rosin resins include rosin-modified phenolic resins, rosin esters, rosin-modified maleic acid resins, polymerized rosin resins, and the like, and at least one rosin resin selected from these is preferred. The softening point is a value measured by the ring and ball method. The softening point can be measured, for example, by the measuring method described in JISK2207. The weight average molecular weight of the rosin ester is preferably 500-3000. 1000 to 2000 is more preferable. Since the rosin resin coats the surface of the pigment and enhances the dispersion stability of the pigment, the combination with the polyurethane resin (A) improves printability at low temperatures.

<Pigment>
Pigments used in the ink of the present invention include organic and inorganic pigments used in general inks, paints, recording materials, and the like. Organic pigments include azo, phthalocyanine, anthraquinone, perylene, perinone, quinacridone, thioindigo, dioxazine, isoindoline, quinophthalone, azomethineazo, ditopyrrolopyrrole, isoindoline, and carbon black. and other pigments. Examples of inorganic pigments include titanium oxide, zinc oxide, zinc sulfide, barium sulfate, calcium carbonate, chromium oxide, silica, red iron oxide, aluminum, and mica (mica). In addition, the C.I. I. Pigments described as pigments can optionally be used. Titanium oxide is preferably titanium oxide whose surface is coated with at least silica or alumina.

These pigments can be used singly or in combination of two or more. The content of the pigment is preferably 2 to 40% by mass, more preferably 5 to 35% by mass, based on the total mass of the ink.

<Organic solvent>
The gravure or flexo ink of the present invention contains an organic solvent to maintain the pigment dispersion state. Preferably, the ink is an organic solvent type ink in which the main component of the liquid medium is an organic solvent. As the organic solvent to be used, a mixed solvent composed of two or more kinds of organic solvents is preferable, and aromatic organic solvents such as toluene and xylene, ketone organic solvents such as methyl ethyl ketone and methyl isobutyl ketone, ethyl acetate, n-propyl acetate, Known organic solvents such as isopropyl acetate, isobutyl acetate, ester-based organic solvents, and alcohol-based organic solvents such as methanol, ethanol, n-propanol, isopropanol, and n-butanol can be used. Among them, organic solvents such as toluene and xylene that do not contain aromatic organic solvents (non-toluene organic solvents) are more preferable. More preferably, the organic solvent does not contain an aromatic organic solvent and/or a ketone organic solvent such as methyl ethyl ketone (hereinafter referred to as "MEK"). Further, a mixed solvent of an ester-based organic solvent and an alcohol-based organic solvent is preferable because printability is improved. A preferred mass ratio of the ester-based organic solvent and the alcohol-based organic solvent (ester-based organic solvent/alcohol-based organic solvent) is 50/50 to 90/10.

<Other additives>
In addition, additives such as leveling agents, antifoaming agents, waxes, plasticizers, light stabilizers, infrared absorbers, ultraviolet absorbers, fragrances, and flame retardants may be added as necessary.

<Other resins>
In the gravure or flexo ink in the present invention, other resins can be used in combination within a range that does not impair the effects of the present invention. Examples of resins used include polyurethane resins other than those described above, chlorinated polypropylene resins, ethylene-vinyl acetate copolymer resins, vinyl acetate resins, polyamide resins, acrylic resins, polyester resins, alkyd resins, polyvinyl chloride resins, Terpene resins, phenol-modified terpene resins, ketone resins, cyclized rubbers, chlorinated rubbers, butyrals, petroleum resins, modified resins thereof, and the like can be mentioned. These resins can be used alone or in combination of two or more.

<Method for producing gravure or flexographic ink>
The gravure or flexographic ink of the present invention is prepared by dispersing a pigment in an organic solvent using a polyurethane resin (A) and, if necessary, a vinyl chloride-vinyl acetate copolymer resin or the like using a disperser, and adding the resulting pigment dispersion. In addition, it can be produced by mixing other resins, various additives, organic solvents, and the like. Commonly used dispersing machines, such as roller mills, ball mills, pebble mills, attritors and sand mills, can be used. The particle size distribution of the pigment in the pigment dispersion is adjusted by appropriately adjusting the size of the grinding media of the disperser, the filling rate of the grinding media, the dispersion processing time, the ejection speed of the pigment dispersion, the viscosity of the pigment dispersion, and the like. be able to. A sand mill is preferably used as the disperser. Further, the gravure or flexographic ink of the present invention preferably has a viscosity of 40 to 600 mPa·s.

<Printing with gravure ink>
(gravure version)
In the present invention, the gravure plate is made of metal and has a cylindrical shape. There are no restrictions on the use of engraving and laser, and settings can be made arbitrarily according to the pattern. A line number of 100 to 300 lines is appropriately used, and the larger the number of lines, the finer the printing is possible.
(Printer)
The printed matter in the present invention is obtained by applying gravure ink using a gravure printing machine, drying it in an oven, and fixing it. The drying temperature is usually about 40-60°C.

<Flexographic ink printing>
(flexographic plate)
Examples of the plate used for flexographic printing in the present invention include a photosensitive resin plate utilizing ultraviolet curing with a UV light source and an elastomer material plate using a direct laser engraving system. Regardless of the method of forming the image area of the flexographic plate, a plate having a screening ruling of 75 lpi or more is used. Any sleeve or cushion tape for attaching the plate can be used.
(Printer)
Flexographic printing machines include CI type multicolor flexographic printing machines, unit type multicolor flexographic printing machines, etc. As for the ink supply system, a chamber system and a two-roll system can be mentioned, and an appropriate printing machine can be used. can.

<Base material 1>
Substrates to which the gravure or flexographic ink of the present invention can be applied include polyethylene, polypropylene and other polyolefin substrates, polycarbonate substrates, polyethylene terephthalate, polylactic acid and other polyester substrates, polystyrene substrates, AS resins, ABS resins, and the like. Polystyrene-based resin, polyamide base material, polyvinyl chloride base material, polyvinylidene chloride base material, cellophane base material, paper base material, aluminum foil base material, etc., or film-like or sheet-like materials made of these composite materials there is something Among them, a polyester base material and a polyamide base material having a high glass transition temperature are preferably used.

The base material may be subjected to vapor deposition coating treatment such as metal oxide on the surface and/or coating treatment such as polyvinyl alcohol. For example, GL- Examples include AE and IB-PET-PXB manufactured by Dai Nippon Printing Co., Ltd. Further, if necessary, those treated with additives such as antistatic agents and ultraviolet inhibitors, and those treated with corona treatment or low-temperature plasma treatment on the surface of the base material can also be used.

<Base material 2>
Substrate 2 may be the same as substrate 1 and may be the same or different. A thermoplastic substrate (sometimes referred to as a sealant) is preferable, and an unstretched polyethylene substrate, an unstretched polypropylene substrate, an unstretched polyester substrate, or the like is preferable.

<Laminate>
A laminate in the present invention refers to a laminate having at least a base material 1, a printed layer, and a base material 2 in this order. It is preferable to use a laminate having at least a base material 1, a printed layer, an adhesive layer, and a base material 2 in this order.
The laminate of the present invention is obtained by providing an adhesive layer on a printed layer of a printed matter printed with gravure or flexographic ink, and bonding (laminating) the base material 2 together. A typical example of lamination processing is a dry lamination method or the like. The dry lamination method is a method in which an adhesive is applied onto a printed layer of a printed material, dried, and laminated by thermocompression bonding with a sealant.

<Adhesive layer>
The adhesive layer is obtained by applying an adhesive and drying it. As the adhesive, a two-liquid type adhesive comprising a mixture of a polyol and an isocyanate curing agent is suitable, and examples of the polyol include polyester-based and polyether-based adhesives. Specific examples include TM-250HV/CAT-RT86L-60, TM-550/CAT-RT37, TM-314/CAT-14B manufactured by Toyo-Morton Co., Ltd.

EXAMPLES The present invention will be described in detail below with reference to Examples, but the present invention is not limited to these Examples. Parts and % in the present invention represent parts by weight and % by weight unless otherwise specified.

(hydroxyl value)
It was obtained according to JIS K0070.
(acid value)
It was obtained according to JIS K0070.
(amine value)
The amine value was obtained in mg of potassium hydroxide equivalent to the equivalent of hydrochloric acid required to neutralize the amino groups contained in 1 g of the resin according to JIS K0070 according to the following method.
0.5 to 2 g of the sample was accurately weighed (sample solid content: Sg). 50 mL of a mixed solution of methanol/methyl ethyl ketone=60/40 (mass ratio) was added to the accurately weighed sample to dissolve the sample. Bromophenol blue was added to the resulting solution as an indicator, and the resulting solution was titrated with a 0.2 mol/L ethanolic hydrochloric acid solution (potency: f). The point at which the color of the solution changed from green to yellow was defined as the end point, and the titration amount (AmL) at this time was used to determine the amine value by the following (formula 2).
(Formula 2) Amine value = (A x f x 0.2 x 56.108) / S [mgKOH/g]

(Weight average molecular weight)
The weight-average molecular weight was obtained by measuring the molecular weight distribution using a GPC (gel permeation chromatography) device (HLC-8220 manufactured by Tosoh Corporation) and obtaining the converted molecular weight using polystyrene as a standard substance. Measurement conditions are shown below.
Column: The following columns were connected in series and used.
TSKgel SuperAW2500 manufactured by Tosoh Corporation
TSKgel SuperAW3000 manufactured by Tosoh Corporation
TSKgel SuperAW4000 manufactured by Tosoh Corporation
TSKgel guard column SuperAWH manufactured by Tosoh Corporation
Detector: RI (differential refractometer)
Measurement conditions: Column temperature 40°C
Eluent: Tetrahydrofuran Flow rate: 1.0 mL/min

(Glass-transition temperature)
The temperature at the inflection point in the baseline shift was determined as the glass transition temperature by differential scanning calorimeter (DSC) measurement, and DSC8231 manufactured by Rigaku Corporation was used as the measuring apparatus. The measurement temperature range was -100 to 200°C.

(softening point)
The softening point of the resin was obtained according to the method described in JISK5902.

(Polyester polyol composed of azelaic acid and diol)
The following polyester polyol composed of azelaic acid and a diol was synthesized according to the method of "Synthesis of polyester polyol" described in JP-A-2016-150941.
MPD/AZ: Polyester polyol having a number average molecular weight of 2000 which is a condensate of methylpentanediol and azelaic acid NPG/AZ: Polyester polyol having a number average molecular weight of 2000 which is a condensate of neopentyl glycol and azelaic acid MPO-BD/AZ: A polyester polyol having a number average molecular weight of 3000, which is a condensate of mixed diol (MPO: BD=9:1) of 3-methyl-1,3-propanediol (MPO) and 1,4-butanediol (BD) and azelaic acid

(Synthesis Example 1) [Polyurethane resin (A) PU1]
100 parts of MPD/AZ (polyol having a number average molecular weight of 2000 which is a condensate of methylpentanediol and azelaic acid), 1 part of 1,4-butanediol (“1,4BD”), isophorone diisocyanate (hereinafter “IPDI” ) was mixed with 32.1 parts of ethyl acetate and allowed to react at 90° C. under a nitrogen atmosphere for 5 hours to obtain a terminal isocyanate urethane prepolymer.
Then 11 parts isophoronediamine (hereinafter "IPDA"), 1.0 part N-(2-aminoethyl)ethanolamine (hereinafter "AEA"), 1.0 part dibutylamine ("DBA") and ethyl acetate and isopropanol ( Mass ratio 60:40) Stir in a mixed solvent, and the obtained terminal isocyanate urethane prepolymer is gradually added at 40°C, then reacted at 80°C for 1 hour to give a solid content of 30% and a hydroxyl value of 3. A polyurethane resin (A) solution PU1 adjusted to 8 mgKOH/g, an amine value of 8.5 mgKOH/g and a weight average molecular weight of 48,000 was obtained.

(Synthesis Examples 2 to 8) [Polyurethane resin (A) PU2 to PU8]
Polyurethane resin (A) solutions PU2 to PU8 were obtained in the same manner as in Synthesis Example 1 using the raw materials shown in Table 1. Abbreviations in Table 1 are as follows.
・MPD/AA: polyester polyol with a number average molecular weight of 2,000 which is a condensate of 3-methyl-1,5-pentanediol and adipic acid ・PEG: polyethylene glycol with a number average molecular weight of 1,000 ・PPG: polypropylene glycol with a number average molecular weight of 1,000

(Comparative Synthesis Examples 1 and 2) [Polyurethane resin (A) PU1C and PU2C]
Polyurethane resin (A) solutions PU1C and PU2C were obtained in the same manner as in Synthesis Example 1 using the raw materials shown in Table 1.

(Example 1)
[Preparation of ink S1]
40 parts of polyurethane resin (A) solution PU1 (solid content 30%), vinyl chloride-vinyl acetate copolymer resin (Solbin TA5R: manufactured by Nissin Chemical Industry Co., Ltd., vinyl chloride: vinyl acetate: vinyl alcohol = 88: 1: 11 glass Transition temperature 78° C., hydroxyl value 90 mgKOH/g (30% solid content ethyl acetate solution)) 10 parts, C.I. I. 10 parts of Pigment Blue (Lionol Blue FG series manufactured by Toyocolor Co., Ltd.) and 40 parts of a mixed solvent of n-propyl acetate (NPAC)/isopropanol (IPA) = 70/30 were mixed with a disper for 10 minutes, and then with a bead mill for 20 minutes. After dispersion, gravure ink S1 was obtained.

<Gravure printing with ink S1>
The ink S1 obtained above was treated with a mixed solvent (methyl ethyl ketone “MEK”: N propyl acetate “NPAC”: isopropanol “IPA” = 30:40:30) to a viscosity of 16 seconds (25°C, Zahn cup No. 3 ), and corona discharge treated surface of a biaxially oriented nylon (NY) base material (N1102, manufactured by Toyobo Co., Ltd., film thickness 15 μm) with Helio 175 line solid plate (plate type compressed, 100% solid pattern) Then, gravure printing was performed at a printing speed of 100 m/min, an oven drying temperature of 50°C, and a room temperature of 5°C to obtain a printed material.
<Dry lamination processing of ink S1 printed matter>
On the upper surface of the printed layer of the printed matter, a polyester urethane laminate adhesive (TM-550/CAT-RT37 manufactured by Toyo-Morton Co., Ltd.) is added with an ethyl acetate solution having a solid content of 30%, and the adhesive layer after drying is 3.0 g / After coating and drying to a thickness of m ² , unstretched polyethylene (PE) having a thickness of 50 μm was adhered to the adhesive layer surface, followed by dry lamination to obtain a laminate. The laminate is composed of NY substrate/ink S1 layer/adhesive layer/polyethylene substrate layer in this order.

(Examples 2 to 24) [Preparation of inks S2 to S24]
Inks S2 to S24 were obtained in the same manner as in Example 1, except that the raw materials shown in Table 2 were used. In addition, printed matter and laminates thereof were obtained.
In addition, the abbreviations in Table 2 represent the following.
・VC-Ac: Vinyl chloride-acrylic copolymer resin Contains 14% by mass of hydroxybutyl acrylate component as a copolymer component Glass transition temperature 65 ° C. Hydroxyl value 60 mg KOH / g Solid content 30% ethyl acetate solution ・NC1: Nitrocellulose nitrogen-containing Amount 11% Solid content 30% by mass isopropanol solution Hariester P: Rosin-modified pentaerythritol ester Weight average molecular weight 1600 Softening point 100°C Acid value 10 mgKOH/g

(Comparative Examples 1 to 7) [Preparation of Inks T1 to T7]
Inks T1 to T6 were obtained in the same manner as in Example 1 above, except that the raw materials shown in Table 3 were used. In addition, printed matter and laminates thereof were obtained.
In addition, the abbreviations in Table 3 represent the following.
・ Z-37: Polyester resin manufactured by Hitachi Chemical Co., Ltd. Glass transition temperature 50 ° C. Weight average molecular weight 40000

(Examples 25-27)
<Flexographic printing of inks S5, S16 and S21>
The above inks S5, S16 and S21 were applied to a flexo printing machine equipped with a flexo plate (photosensitive resin plate, FLEXCEL NXH digital flexo plate manufactured by KODAK, plate thickness: 1.14 mm, plate line number: 150 lpi) and an anilox roll (900 lpi, 3 cc/m ² ). (MIRAFLEX CM), printing was performed on the corona discharge treated surface of a biaxially oriented nylon (NY) substrate (N1102, manufactured by Toyobo Co., Ltd., film thickness 15 μm) at a speed of 150 m/min at 5° C. to obtain a printed matter. . The drying conditions for the printed layer were an intercolor dryer of 100°C and a tunnel dryer of 100°C.
<Dry lamination processing>
On the upper surface of the printed layer of the printed matter printed with the above inks S5, S16 and S21, a polyester urethane lamination adhesive (TM-550/CAT-RT37 manufactured by Toyo-Morton Co., Ltd.) was applied with an ethyl acetate solution having a solid content of 30%. After coating and drying so that the adhesive layer is 3.0 g / m ² , unstretched polyethylene (PE) with a thickness of 50 μm is attached to the adhesive layer surface and dry lamination is performed to form a laminate. Obtained. The laminate is composed of NY substrate/ink S1 layer/adhesive layer/polyethylene substrate layer in this order.

<Evaluation>
The following evaluations were carried out using the inks, prints and laminates of Examples and Comparative Examples. The results are shown in Tables 2-1, 2-2 and 3, respectively.

<Low temperature aging stability>
Each of the inks S1 to S24 and T1 to T7 obtained in Examples and Comparative Examples was stored at 5°C for 7 days, and evaluated by observing the state before and after storage and measuring the viscosity. It was confirmed by the number of seconds of outflow.
[Evaluation criteria]
A. No liquid separation or sedimentation, viscosity change less than 1 second (excellent)
B. There is some liquid separation, but no precipitation, and the viscosity change is 1 second or more and less than 2 seconds (good)
C. Liquid separation and sedimentation are slightly observed, viscosity change is 2 seconds or more and less than 5 seconds (practical use possible)
D. Liquid separation and sedimentation are slightly observed, viscosity change is 5 seconds or more and less than 10 seconds (slightly poor)
E. Severe liquid separation and sedimentation were observed, and the viscosity change was more than 10 seconds (poor).
Note that A, B, and C are ranges that pose no problem in practice.

<Low temperature plate fogging>
The viscosity of the inks S1 to S24 and T1 to T7 obtained in Examples and Comparative Examples was measured using a mixed solvent (n-propyl acetate: methyl ethyl ketone: isopropyl alcohol = 40:40:20). 3 for 15 seconds, and after 90 minutes of idling of the plate in the gravure printing machine (at 5° C.), the area of the plate fogging portion was visually determined and evaluated.
[Evaluation criteria]
AA. No plate fogging area (extremely good)
A. Plate fogging area is less than 2% (excellent)
B. Plate fogging area of 2% or more and less than 5% (good)
C. Plate fogging area of 5% or more and less than 10% (practical use possible)
D. Plate fogging area of 10% or more and less than 25% (slightly poor)
E. Plate fogging area is 25% or more (defective)
Incidentally, AA, A, B and C are within practically non-problematic ranges.

<Low temperature lamination strength>
Laminates obtained using inks S1 to S24 and T1 to T7 obtained in Examples and Comparative Examples were stored at 5° C. for 7 days, and the printed portion was cut to a width of 15 mm for each, and the ink layer and the substrate surface were measured. After peeling at , the peel strength (laminate strength) was measured at 5°C with a 201 universal tensile tester manufactured by Intesco.
[Evaluation criteria]
A. 2.0N or more (excellent)
B. 1.5 N or more and less than 2.0 N (good)
C. 1.0N or more and less than 1.5N (Practical)
D. 0.5 N or more and less than 1.0 N (slightly poor)
E. Less than 0.5N (defective)
Note that A, B, and C are ranges that pose no problem in practice.

<Evaluation of low-temperature plate entanglement>
Inks S5, S16 and S21 were evaluated for plate entanglement in 3% halftone dot areas after 2000 m printing with a flexo printer at a printing speed of 150 m/min.
[Evaluation criteria]
A. The image is clear with no thickening of the 3% halftone dot portion. (excellent)
B. Although the 3% halftone dot portion is slightly thickened, a clear image is formed. (Good)
C. A slight thickening is observed in the 3% halftone dot portion, but the halftone dots are not connected to each other. (Practical)
D. The shape of the 3% halftone dot portion is lost, and the connection of the halftone dots (dot bridge) or staining is observed. (defective)
Note that A, B, and C are ranges that pose no problem in practice.

<Residual solvent>
For each of the prints using the inks S1 to S24 and T1 to T7 obtained in Examples and Comparative Examples, the prints were heated to 80° C. in a closed Erlenmeyer flask to evaporate the solvent and subjected to gas chromatography (manufactured by GL Sciences, GC-4000) to confirm the amount of volatile solvent.
[Evaluation criteria]
A. Less than ² mg/m2 (excellent)
B. ² mg/ ^m2 or more and less than 4 mg/m2 (good)
C. 4 mg/m ² or more and less than 6 mg/m ² (practical)
D. 6 mg/ ^m2 or more and less than 8 mg/ ^m2 (slightly poor)
E. 8 mg/ ^m2 or more (defective)
Note that A, B, and C are ranges that pose no problem in practice.

As a result of the above studies, it was possible to provide a gravure or flexo ink which is excellent in ink stability over time, printability and lamination strength even under low temperature conditions, and which does not increase residual solvent.

The gravure or flexographic inks of the present invention are not limited to the flexible packaging laminate field, but can also be applied for surface printing.

Claims (4)

A gravure or flexo ink containing a polyurethane resin (A) as a binder resin and an organic solvent, wherein the gravure or flexo ink satisfies the following requirements (1) to (4).
(1) Polyurethane resin (A) contains a structural unit derived from polyester polyol consisting of a dibasic acid containing azelaic acid and a diol .
(2) The polyurethane resin (A) contains 10% by mass or more of structural units derived from azelaic acid in the total mass .
(3) The binder resin further contains at least one resin (B) selected from the group consisting of vinyl chloride copolymer resins, cellulose resins and rosin resins.
(4) The binder resin is polyurethane resin (A) and resin (B), and the mass ratio (A):(B) of polyurethane resin (A) and resin (B) is 95:5 to 30:70. contains 2. The gravure or flexo ink according to claim 1, wherein the polyurethane resin (A) further contains structural units derived from polyether polyol. A printed matter comprising a base material 1 and a printed layer comprising the gravure or flexographic ink according to claim 1 or 2 . A laminate having a substrate 2 on the printed layer of the printed matter according to claim 3 .