Gravure inks and printed materials for paper substrates

Abstract

The present invention aims to provide a gravure ink for paper substrates that has special effects in terms of adhesion, abrasion resistance, water abrasion resistance, heat resistance, ink stability, crack resistance, and printability. [Solution] A gravure ink for paper substrates comprising a vinyl chloride resin and a rosin resin, wherein the vinyl chloride resin comprises a vinyl chloride resin (A) having an acid value, and the rosin resin has an acid value, or the gravure ink for paper substrates further comprising a vinyl chloride resin (B) that does not have an acid value.

Description

Technical Field

[0001] The present invention relates to gravure ink for paper substrates and printed matter.

Background Art

[0002] Conventionally, the gravure method has been used for printing on paper substrates such as tobacco, paper cups, and snack boxes, and the ink used at that time is gravure ink for paper substrates. Details of this gravure ink for paper substrates are described in Patent Document 1, in which it is disclosed that it contains a polymerized rosin composed of nitrocellulose and a biomass component. By using these components, it is possible to maintain printing suitability for paper substrates while reducing the environmental load, and this method is evaluated as effective.

[0003] Furthermore, Patent Document 2 discloses a gravure ink for paper substrates for forming a printing layer in a laminate for containers having at least a protective layer or a thermoplastic synthetic film, paper, and a printing layer, and laminated in that order, which contains a binder resin, a pigment, a wax, and an organic solvent that does not contain an aromatic solvent, the binder resin contains a vinyl chloride vinyl acetate copolymer resin and rosin or a rosin derivative, and the particle diameter of the wax is 30 μm or less.

[0004] However, the gravure inks described in Patent Document 1 or 2 had room for improvement in various physical properties such as heat resistance and abrasion resistance.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Summary of the Invention

[0006] This invention has been made in view of the above-mentioned conventional problems, and aims to provide a gravure ink for paper substrates and printed materials that have excellent physical properties such as adhesion, abrasion resistance, water abrasion resistance, heat resistance, ink stability, crack resistance, and printability. [Means for solving the problem]

[0007] The present invention relates to a gravure ink for paper substrates comprising a vinyl chloride resin and a rosin resin, This invention relates to a gravure ink for paper substrates, wherein the vinyl chloride resin contains a vinyl chloride resin (A) having an acid value, and the rosin resin also has an acid value.

[0008] The present invention relates to a gravure ink for paper substrates, wherein the vinyl chloride resin further comprises a vinyl chloride resin (B) that does not have an acid value.

[0009] The present invention relates to a gravure ink for paper substrates, wherein the acid value of the rosin-based resin is 30 mg KOH / g or less.

[0010] The present invention relates to a gravure ink for paper substrates, wherein the mass ratio of the total mass of a vinyl chloride resin (A) having an acid value and a vinyl chloride resin (B) not having an acid value to a rosin resin is 51:49 to 99:1.

[0011] The present invention further relates to a gravure ink for a paper substrate, comprising a resin-type dispersant.

[0012] The present invention further relates to a gravure ink for a paper substrate, comprising a plasticizer.

[0013] The present invention relates to a gravure ink for a paper substrate, wherein the rosin-based resin includes a rosin ester resin.

[0014] The present invention further relates to a gravure ink for a paper substrate, comprising paraffin wax.

[0015] The present invention relates to a printed material having a printed layer formed on a paper substrate using gravure ink for paper substrates. [Effects of the Invention]

[0016] The present invention makes it possible to provide gravure inks and printed materials for paper substrates that have excellent physical properties such as adhesion, abrasion resistance, water abrasion resistance, heat resistance, ink stability, crack resistance, and printability. [Modes for carrying out the invention]

[0017] The embodiments of the present invention will be described in detail below, but the description of the constituent elements described below is just one example (representative example) of an embodiment of the present invention, and the present invention is not limited to these contents unless it exceeds the gist of the invention.

[0018] In the following, gravure inks for paper substrates may be abbreviated as simply "gravure ink" or "ink," but these are synonymous.

[0019] The gravure ink for paper substrates in the present invention comprises a vinyl chloride resin and a rosin resin as binder resins. Furthermore, the vinyl chloride resin contains a vinyl chloride resin (A) having an acid value, and the rosin resin also has an acid value. The presence of an acid value in the vinyl chloride resin (A) improves abrasion resistance. In addition, the presence of an acid value in the rosin resin improves adhesion and crack resistance. In particular, the presence of an acid value of 35 mgKOH / g or less in the rosin resin improves abrasion resistance and crack resistance. It is presumed that combining a vinyl chloride resin having an acid value and a rosin resin having an acid value will significantly improve the physical properties of the printed film, such as adhesion, abrasion resistance, and crack resistance, and contribute to solving the problem of the present invention.

[0020] In one embodiment, the inclusion of a rosin ester resin as the rosin-based resin is expected to improve ink stability and crack resistance. Also, in one embodiment, the gravure ink for paper substrates contains a vinyl chloride-based resin (B) having no acid value, thereby maintaining water rub resistance, ink stability, and printing suitability.

[0021] Also, in one embodiment, a resin-type dispersant is contained, thereby enhancing the dispersibility of the pigment and enabling a uniform printing result. Furthermore, since a plasticizer such as dibutyl sebacate is blended, the flexibility of the ink film increases, improving the adhesion to paper and durability. Also, by adding paraffin wax, a smooth printing surface is achieved and the effect of reducing the frictional resistance is obtained. Due to these characteristics, the ink of the present invention can produce printed matter of excellent quality when applied to gravure printing. This ink has a wide range of characteristics and is expected to be widely applied to commercial printing, packaging materials, etc. Such a combination of characteristics enables the gravure ink for paper substrates of the present invention to play an important role in the printing industry. Note that this consideration is based on speculation and does not limit the invention in any way.

[0022] (Binder resin) The gravure ink for paper substrates of the present invention contains a vinyl chloride-based resin and a rosin-based resin as the binder resin. In particular, the vinyl chloride-based resin has a vinyl chloride-based resin (A) having an acid value, and the rosin-based resin has an acid value. By combining these resins, flexibility is imparted to the resin and the adhesion to the substrate is improved, so it is presumed that the adhesion, friction resistance, and crack resistance are significantly improved. The gravure ink for paper substrates of the present invention preferably contains a total of 5 to 40% by mass of the vinyl chloride-based resin and the rosin-based resin in the total mass of the ink, and more preferably 10 to 30% by mass. When the total amount of the vinyl chloride-based resin and the rosin-based resin contained in the total mass of the ink is within the above range, the ink stability tends to improve.

[0023] (Vinyl chloride-based resin (A)) The gravure ink for paper substrates of the present invention contains a vinyl chloride resin (A) having an acid value. The acid value of the vinyl chloride resin (A) improves the chemical properties of the binder resin, and tends to improve the abrasion resistance of the ink. Suitable examples of vinyl chloride resin (A) include vinyl chloride-vinyl acetate copolymer resins and vinyl chloride acrylic copolymer resins having an acid value. The gravure ink for paper substrates of the present invention preferably contains 1 to 20% by mass of vinyl chloride resin (A) in the total mass of the ink, and more preferably contains 2 to 15% by mass.

[0024] (Vinyl chloride resin (B)) The gravure ink for paper substrates of the present invention preferably uses a vinyl chloride resin (B) that does not have an acid value in addition to the vinyl chloride resin (A) described above. Suitable examples of the vinyl chloride resin (B) that does not have an acid value include vinyl chloride-vinyl acetate copolymer resin and vinyl chloride acrylic copolymer resin that do not have an acid value. Using a vinyl chloride resin (B) that does not have an acid value tends to improve water abrasion resistance, ink stability, and printability. The gravure ink for paper substrates of the present invention preferably contains 1 to 20% by mass of vinyl chloride resin (B) in the total mass of the ink, and more preferably contains 2 to 15% by mass.

[0025] The mass ratio of the vinyl chloride resin (A) having an acid value to the vinyl chloride resin (B) not having an acid value is preferably 10:90 to 90:10, more preferably 15:85 to 60:40, and even more preferably 20:80 to 50:50.

[0026] (Vinyl chloride-vinyl acetate copolymer resin) From the viewpoint of abrasion resistance and heat resistance, the vinyl chloride resin preferably contains a vinyl chloride-vinyl acetate copolymer resin. This copolymer resin is formed by copolymerizing vinyl chloride and vinyl acetate and other monomers. Specifically, it can be synthesized by adding vinyl chloride monomer and vinyl acetate monomer to a flask and, if necessary, adding other monomers, initiators and chain transfer agents to carry out a copolymerization reaction. As other monomers, it is preferable to include constituent units derived from acidic monomers such as acrylic acid and itaconic acid. Furthermore, of 100% by mass of the solid content of the vinyl chloride-vinyl acetate copolymer resin, vinyl chloride units are preferably 65 to 99% by mass, and more preferably 70 to 95% by mass. Vinyl acetate units are preferably 1 to 35% by mass, and more preferably 5 to 30% by mass. If other monomers are included, the other monomer units are preferably 0.1 to 15% by mass, and more preferably 0.1 to 10% by mass. The vinyl chloride-vinyl acetate copolymer resin is preferably contained in the total mass of the ink in an amount of 1 to 50% by mass, and more preferably 5 to 30% by mass.

[0027] When the vinyl chloride-vinyl acetate copolymer resin has an acid value, it is preferably 1 to 30 KOH mg / g, more preferably 3 to 20 KOH mg / g, and even more preferably 5 to 15 KOH mg / g. When the acid value is within the above range, adhesion, abrasion resistance, and crack resistance tend to improve. The weight-average molecular weight of the vinyl chloride-vinyl acetate copolymer resin is preferably 5,000 to 100,000, and even more preferably 20,000 to 80,000. Furthermore, the glass transition temperature is preferably 65 to 85°C. When the weight-average molecular weight of the vinyl chloride-vinyl acetate copolymer resin is within the above range, the adhesion to the aluminum substrate is further improved in combination with the above acid value. In this specification, the glass transition temperature represents the midpoint between the glass transition start temperature and end temperature, determined by DSC (Differential Scanning Calorimetry).

[0028] (Vinyl chloride acrylic copolymer resin) The vinyl chloride resin may also preferably contain a vinyl chloride acrylic copolymer resin. The vinyl chloride acrylic copolymer resin is preferably present in an amount of 1 to 50% by mass, and more preferably in an amount of 5 to 30% by mass, in the total mass of the ink. If the vinyl chloride acrylic copolymer resin has an acid value, the acid value is preferably 1 to 30 KOH mg / g, more preferably 3 to 20 KOH mg / g, and even more preferably 5 to 15 KOH mg / g. This tends to improve abrasion resistance.

[0029] The "acid value" of vinyl chloride resin (A) and rosin resin (described later) is an index indicating the number of milligrams of potassium hydroxide required to neutralize the acid groups contained in the resin. This value is measured by an alkaline titration method in accordance with JIS K0070. Specifically, a certain amount of potassium hydroxide solution is added dropwise to the resin sample, and the amount of potassium hydroxide consumed until the acid groups are completely neutralized is calculated. From this amount of potassium hydroxide consumed, the total amount of acid groups in the resin is determined, and this amount expressed in milligrams is the acid value.

[0030] In the gravure ink for paper substrates of the present invention, the mass ratio of the total mass of the vinyl chloride resin (A) having an acid value and the vinyl chloride resin (B) not having an acid value to the rosin resin is preferably 51:49 to 99:1, more preferably 60:40 to 95:5, and even more preferably 65:35 to 90:10. By using the vinyl chloride resin (A) having an acid value and the vinyl chloride resin (B) not having an acid value in combination with the rosin resin within the above mass range, ink stability is improved, and ease of handling during the printing process, as well as abrasion resistance and crack resistance tend to improve.

[0031] (Rosin-based resin) The gravure ink for paper substrates of the present invention contains a rosin-based resin, and in particular contains a rosin-based resin having an acid value. The acid value of the rosin-based resin causes interaction with the substrate surface, which tends to improve adhesion and crack resistance. The rosin-based resin contained in the gravure ink for paper substrates of the present invention contains a rosin-modified resin, and for example, rosin-modified maleic acid resin, rosin ester resin, rosin phenol resin, polymerized rosin resin, etc. are preferred, and rosin-modified maleic acid resin and rosin ester resin are particularly preferred. The inclusion of rosin-modified maleic acid resin and rosin ester resin improves adhesion and crack resistance.

[0032] It is known that many rosin-based resins used in general gravure inks have an acid value of 0.1 mg KOH / g or higher. In particular, the acid value of the rosin-based resin used in the gravure ink for paper substrates of the present invention is preferably 1 to 30 mg KOH / g, more preferably 3 to 25 mg KOH / g, and even more preferably 4 to 15 mg KOH / g. Setting the acid value within this range tends to improve adhesion and crack resistance, making it potentially very useful as a printing ink. Furthermore, the softening point of the rosin-based resin used in the gravure ink for paper substrates of the present invention is preferably 50 to 180°C, more preferably 60 to 150°C, and even more preferably 70 to 100°C. In the gravure ink for paper substrates of the present invention, the rosin-based resin is preferably contained in an amount of 0.1 to 20% by mass, and more preferably in an amount of 0.5 to 15% by mass, of the total mass of the ink.

[0033] (Rosin ester resin) The rosin-based resin used in the gravure ink for paper substrates of the present invention is preferably a rosin ester resin, which is an ester condensation resin of a low molecular weight polyol with a molecular weight of less than 1000 and rosin acid. The low molecular weight polyol preferably has 2 to 4 hydroxyl groups (sometimes abbreviated as 2 to 4 functionalities). Furthermore, the low molecular weight polyol is more preferably 50 to 500. Examples of rosin acid include abietic acid, neoabietic acid, palastic acid, pimaric acid, isopimaric acid, and dehydroabietic acid. Suitable low molecular weight polyols include bifunctional low molecular weight polyols such as ethylene glycol, 1,3-propanediol, 1,4-butanediol, and 1,10-decanediol; trifunctional low molecular weight polyols such as glycerin and trimethylolpropane; and tetrafunctional low molecular weight polyols such as erythritol and pentaerythritol. Among these, trifunctional low molecular weight polyols are preferred. When the gravure ink for paper substrates of the present invention contains a rosin ester resin, it is preferable that it contains 0.1 to 20% by mass, and more preferably 0.5 to 15% by mass, of the total mass of the ink.

[0034] The acid value of the rosin ester resin used in the gravure ink for paper substrates of the present invention is preferably 1 to 30 mg KOH / g, more preferably 3 to 25 mg KOH / g, and even more preferably 4 to 15 mg KOH / g. Furthermore, the softening point of the rosin ester resin is preferably 50 to 180°C, more preferably 60 to 150°C, and even more preferably 70 to 100°C. Specifically, examples include "Harima-c" R-80, "Haritac" FK-100, FK-125, F-85, SE-10, "Hariester" DS-70L, DS-130 from Harima Chemicals Group Co., Ltd., and "Ester Gum" AA-G, AA-L, H, HP, and "Pensel" GA-100, AZ, D-125 from Arakawa Chemical Industries, Ltd.

[0035] (Rosin-modified maleic acid resin) The rosin-based resin used in the gravure ink for paper substrates of the present invention is preferably a rosin-modified maleic acid resin. When the gravure ink for paper substrates of the present invention contains a rosin-modified maleic acid resin, it is preferably present in an amount of 0.1 to 20% by mass, and more preferably 0.5 to 15% by mass, in the total mass of the ink. The acid value of the rosin-modified maleic acid resin of the present invention is preferably 1 to 30 mgKOH / g, more preferably 3 to 25 mgKOH / g, and even more preferably 4 to 15 mgKOH / g. Furthermore, the oil softening point of the rosin-modified maleic acid resin is preferably 50 to 180°C, more preferably 60 to 150°C, and even more preferably 70 to 100°C. Specifically, examples include "Harima-c" T-80, R-100, and M-453 manufactured by Harima Chemicals Group Co., Ltd., and "Marquid" No. 1, 2, 5, 6, 8, 31, 32, and 33 manufactured by Arakawa Chemical Industries, Ltd.

[0036] (Organic solvents) The gravure ink for paper substrates of the present invention preferably contains an organic solvent. Preferably, the organic solvent includes ethyl acetate, propyl acetate and other ester-based organic solvents; acetone, methyl ethyl ketone (MEK), methyl isobutyl ketone and other ketone-based organic solvents; and ethanol, n-propanol, isopropanol, butanol and other alcohol-based organic solvents. In particular, it is preferable that the ester-based organic solvent and the ketone-based organic solvent are present in a mass ratio of 95:5 to 30:70, and even more preferably 80:20 to 50:50. From an environmental perspective, it is preferable that the gravure ink for paper substrates does not contain toluene and other aromatic organic solvents; however, from the standpoint of solving the problem, this does not particularly hinder its use. Preferably, the organic solvent is present in an amount of 50 to 90% by mass of the total mass of the gravure ink for paper substrates.

[0037] (Coloring agent) The gravure ink for paper substrates of the present invention may also preferably contain a colorant. The content of the colorant is preferably 1 to 60% by mass, and more preferably 5 to 50% by mass, of the total mass of the printed layer. Pigments are preferred as the colorant, and either organic pigments or inorganic pigments can be used. These may be used alone or in combination of two or more.

[0038] (Organic pigments) Specific examples of organic pigments are shown using their CI numbers from the Colour Index International (CI). Preferably, CI Pigment Red 57:1, CI Pigment Red 48:1, CI Pigment Red 48:2, CI Pigment Red 48:3, CI Pigment Red 146, CI Pigment Red 242, CI Pigment Yellow 83, CI Pigment Yellow 14, CI Pigment Orange 64, CI Pigment Orange 38, CI Pigment Orange 34, CI Pigment Orange 13, CI Pigment Yellow 180, CI Pigment Yellow 139, CI Pigment Red 185, CI Pigment Red 122, C These include I Pigment Red 178, CI Pigment Red 149, CI Pigment Red 144, CI Pigment Red 166, CI Pigment Violet 23, CI Pigment Violet 37, CI Pigment Blue 15, CI Pigment Blue 15:1, CI Pigment Blue 15:2, CI Pigment Blue 15:3, CI Pigment Blue 15:4, CI Pigment Blue 15:6, CI Pigment Green 7, CI Pigment Black 7, etc. These may be used individually or in combination of two or more types.

[0039] (Inorganic pigments) Examples of inorganic pigments include titanium dioxide, zinc oxide, zinc sulfide, barium sulfate, calcium carbonate, chromium oxide, aluminum hydroxide, silica, kaolin, clay, talc, aluminum particles, mica, bronze powder, chrome vermilion, lead yellow, cadmium yellow, cadmium red, ultramarine, Prussian blue, red iron oxide, yellow iron oxide, iron black, titanium dioxide, zinc oxide, etc. Aluminum can be of the leafing or non-leafing type, but the non-leafing type is preferred.

[0040] (Additives) The gravure ink for paper substrates of this embodiment may contain additives such as plasticizers, waxes, resin-type dispersants, tackifiers, crosslinking agents, lubricants, antiblocking agents, antistatic agents, and surfactants as optional components. Preferably, the total amount of additives in the ink is 0.01 to 15% by mass, and more preferably 0.1 to 10% by mass. These are used selectively to improve the performance of the gravure ink for paper substrates. Plasticizers increase the flexibility of the ink coating, tackifiers ensure that the ink is securely fixed to the printing surface, crosslinking agents improve the durability of the ink layer, and lubricants reduce friction during printing. Antiblocking agents prevent the printed materials from sticking together when they overlap, and antistatic agents prevent problems caused by static electricity. Surfactants adjust the surface tension of the ink and help it spread uniformly on the printing surface. Furthermore, the gravure ink for paper substrates of this embodiment may also contain additional waxes such as polyolefin wax and paraffin wax, and leveling agents, to the extent that it does not degrade performance. This enables improved print quality and adaptation to specific applications, providing gravure inks for paper substrates that can meet a wider range of needs.

[0041] (Plasticizer) The gravure ink for paper substrates of the present invention may also preferably contain a plasticizer. The inclusion of a plasticizer in the gravure ink for paper substrates is done to improve printability and post-processing properties, and is appropriately blended with the expectation of reducing residual solvents. In the present invention, improvement in abrasion resistance and crack resistance can be expected by selecting an appropriate plasticizer and adjusting its content. Specific compounds of plasticizers include fatty acid esters such as 2-ethylhexyl stearate, 2-ethylhexyl palmitate, dibutyl sebacate, and dioctyl sebacate, epoxidized soybean oil, fatty acid triglycerides, sulfonamide derivatives such as ethyltoluenesulfonamide, and citric acid derivatives such as tributyl acetylcitrate and tributyl citrate. Among these, fatty acid esters are preferred plasticizers because they have a particularly low odor. In the present invention, it is preferable to include 0.1 to 20% by mass of plasticizer relative to the total solid content of the ink, and more preferably 1 to 10% by mass.

[0042] (Resin-type dispersant) The gravure ink for paper substrates of the present invention may also preferably contain a resin-type dispersant. The resin-type dispersant has an affinity site for the pigment composition that has the property of adsorbing to the pigment composition, and a site that is compatible with the pigment composition carrier, and functions to stabilize the dispersion on the pigment composition carrier by adsorbing to the pigment composition. Specifically, resin-type dispersants include polyurethane, polyacrylates and other polycarboxylic acid esters, unsaturated polyamides, polycarboxylic acids, polycarboxylic acid (partial)amine salts, polycarboxylic acid ammonium salts, polycarboxylic acid alkylamine salts, polysiloxanes, long-chain polyaminoamide phosphates, hydroxyl group-containing polycarboxylic acid esters, modified products thereof, oily dispersants such as amides and their salts formed by the reaction of poly(lower alkyleneimines) with polyesters having free carboxyl groups, (meth)acrylic acid-styrene copolymer resins, (meth)acrylic acid-(meth)acrylic acid ester copolymer resins, styrene-maleic acid copolymer resins, water-soluble resins and water-soluble polymer compounds such as polyvinyl alcohol and polyvinylpyrrolidone, polyester-based, acrylic-based, modified polyacrylate-based, ethylene oxide / propylene oxide adduct compounds, phosphate ester-based, etc. These can be used individually or in combination of two or more, but are not necessarily limited to these.

[0043] The resin-type dispersant has the ability to effectively disperse pigment particles, and as a result, by including the resin-type dispersant, the pigment can be uniformly distributed in the gravure ink for paper substrates of the present invention. This uniform distribution of pigment improves the quality of the gravure ink for paper substrates of the present invention, particularly improving ink stability, crack resistance, and printability. The content of the resin-type dispersant is preferably 0.01 to 20% by mass, and more preferably 0.1 to 10% by mass, based on the total mass of the ink. The resin-type dispersant may also have an acid value, which is preferably 1 to 200 mg KOH / g, more preferably 20 to 150 mg KOH / g, and even more preferably 40 to 100 mg KOH / g.

[0044] (wax) The gravure ink for paper substrates of the present invention may also preferably contain wax. Specifically, examples include amide waxes and hydrocarbon waxes, with hydrocarbon wax being more preferable. Examples of hydrocarbon waxes include polyethylene wax, Fischer-Tropsch wax, paraffin wax, microstarin wax, and polypropylene wax. Among these, paraffin wax and polyethylene wax are preferred, with paraffin wax being more preferable. The amount of wax is preferably 0.01 to 10% by mass, and more preferably 0.1 to 5% by mass, of the total mass of the ink.

[0045] (Paraffin wax) Paraffin wax is a type of hydrocarbon with a high number of carbon atoms and a high degree of saturation. Including paraffin wax is expected to improve friction resistance and water friction resistance. The paraffin wax content is preferably 0.01 to 10% by mass, and more preferably 0.1 to 5% by mass, relative to the total solids mass of the ink. Using this range tends to improve the drying properties of the ink and the smoothness of the printed layer surface, stabilize the ink's behavior during printing, and result in high-quality printed materials.

[0046] The gravure ink for paper substrates in the present invention may also contain resins other than those listed above. Examples include, but are not limited to, chlorinated polypropylene resin, ethylene-vinyl acetate copolymer resin, vinyl acetate resin, alkyd resin, terpene resin, phenol-modified terpene resin, ketone resin, cyclized rubber, chlorinated rubber, butyral, petroleum resin, dimer acid-based resin, maleic acid-based resin, dammar resin, copal resin, and oxidized polypropylene. These resins may be contained in the total mass of the ink at a solid content of 30% by mass or less.

[0047] The method for manufacturing the gravure ink for paper substrates according to the present invention will now be described. First, an initial mixing step is performed using vinyl chloride resins (A) and (B), rosin resin, an organic solvent, and additives as needed. In this step, the ingredients are mixed using a stirring mixer. Next, the resulting mixture is moved to a pigment dispersion step. In this step, the pigment is effectively dispersed using a disperser such as a bead mill. To the dispersion liquid after dispersion, vinyl chloride resins (A) and (B), rosin resin, an organic solvent, and additives as needed are further added to adjust the final properties of the ink. Through this series of processes, the gravure ink for paper substrates according to the present invention is manufactured. This method requires appropriate formulation and process control while considering the characteristics of each component, making it possible to manufacture high-quality ink.

[0048] (Printing method) The preferred printing method for gravure inks for paper substrates is gravure printing. In gravure printing, an intaglio plate for gravure printing is used to form an image using multi-color printing. Specifically, the type of plate used is engraved, laser, or etching, and the printing speed is preferably in the range of 10 to 300 m / min. The printing press is also equipped with an oven to volatilize volatile components such as organic solvents to obtain the printed layer, and as the printed material passes through the oven, the volatilization (also called drying) occurs and the printed layer is fixed to the substrate. The temperature of the oven is preferably 30 to 150°C. By using gravure printing technology, gravure inks for paper substrates can be uniformly and reliably fixed to a wide variety of paper substrates, and as a result, high-quality printed materials can be produced.

[0049] (Paper base material) The gravure ink for paper substrates of the present invention is mainly applicable to a wide range of paper substrates, including paper substrates, fine paper, art paper, coated paper, and polyethylene coated paper. These paper substrates are printed using a gravure printing press. The printed materials obtained by this printing process are used as packaging materials for products such as containers and food. Particular preference is for use as packaging for containers. Thus, the gravure ink for paper substrates of the present invention can be used on a wide range of paper substrates, with or without a coating layer, and can provide printed materials suitable for various packaging applications.

[0050] In the case of paper substrates, it is desirable that the paper substrates usable for printed materials of the present invention possess specific physical and chemical properties. This is important for improving print quality and durability. For example, paper thickness, texture, and water absorption affect the printing results, so these properties must be appropriately selected according to the intended use of the printed material. Compatibility with the inks used in the printing process must also be considered. The drying speed of the ink and the color fixation are influenced by the surface properties of the paper substrate, so the selection of paper substrates that take these factors into consideration is required. Furthermore, from the perspective of reducing environmental impact, it is important to use recyclable materials and to select harmless materials that prioritize safety. Based on these points, the present invention recommends selecting the optimal paper substrate according to the intended use and function of the final printed material. [Examples]

[0051] The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples. In the present invention, parts and % refer to parts by mass and mass %, respectively, unless otherwise noted.

[0052] (Acid value) The calculation was performed according to JIS K0070.

[0053] (Weight average molecular weight) The weight-average molecular weight was determined by measuring the molecular weight distribution using a GPC (gel permeation chromatography) instrument (HLC-8220, manufactured by Tosoh Corporation) and calculating the converted molecular weight using polystyrene as a standard substance. The measurement conditions are shown below. Columns: The following columns were used, connected in series. Tosoh Corporation Guard Column HXL-H TSKgel G5000HXL manufactured by Tosoh Corporation TSKgel G4000HXL manufactured by Tosoh Corporation TSKgel G3000HXL manufactured by Tosoh Corporation TSKgel G2000HXL manufactured by Tosoh Corporation Detector: RI (Differential Refractometer) Measurement conditions: Column temperature 40°C Eluent: Tetrahydrofuran Flow rate: 1.0mL / min

[0054] (Calculation of the content ratio in 100% by mass of solids of vinyl chloride-vinyl acetate copolymer resin) Vinyl chloride units: Determined by burning the sample in oxygen using a platinum catalyst, absorbing the resulting hydrochloric acid in water, and titrating with silver nitrate solution. Vinyl acetate units were calculated using the ratio of vinyl chloride units to vinyl acetate units, which was quantified from the area ratio of the absorption intensity of C-Cl bonds to the absorption intensity of C=O bonds using Fourier transform infrared absorption spectroscopy (FT-IR), and the content of the vinyl chloride units mentioned above. Acid monomer units: The weight ratio was determined from the molar amount calculated from the above acid value.

[0055] (Glass transition temperature) The glass transition temperature was determined by DSC (Differential Scanning Calorimetry). A Rigaku DSC8231 was used, with a measurement temperature range of 25 to 180°C, a heating rate of 10°C / min, and the midpoint between the glass transition start and end temperatures defined as the glass transition temperature.

[0056] (Synthesis Example 1) (Synthesis of vinyl chloride-vinyl acetate copolymer resin (A2)) In a 6L stainless steel pressure polymerization vessel equipped with a stirrer, thermometer, and nitrogen gas inlet, after purging with nitrogen, 900 parts of deionized water, 1100 parts of methanol, 300 parts of vinyl chloride, 100 parts of vinyl acetate, 3 parts of acrylic acid, 1 part of azobisisobutyronitrile, and 10 parts of n-dodecyl mercaptan (chain transfer agent) were charged, and the reaction was started by heating to 70°C while stirring. Subsequently, 400 parts of vinyl chloride, 200 parts of vinyl acetate, and 3 parts of acrylic acid were continuously added over 8 hours to carry out the polymerization reaction. The vinyl chloride used was solidified at -30°C. When the pressure inside the polymerization vessel reached 0.5 kg / cm² (gauge pressure) after 12 hours of reaction, the remaining pressure was released and the mixture was cooled, washed three times with 1500 parts of deionized water, filtered, and dried at 50°C for 24 hours to obtain vinyl chloride-vinyl acetate copolymer resin (A2). The obtained vinyl chloride-vinyl acetate copolymer resin (A2) contained 70% by mass of vinyl chloride units, 29.6% by mass of vinyl acetate units, and 0.4% by mass of acrylic acid units. Its weight-average molecular weight was 40,000, its glass transition temperature was 69°C, and its acid value was 3 mg KOH / g.

[0057] (Synthesis Example 2) (Synthesis of vinyl chloride-vinyl acetate copolymer resin (A3)) In a 6L stainless steel pressure polymerization vessel equipped with a stirrer, thermometer, and nitrogen gas inlet, after purging with nitrogen, 900 parts of deionized water, 1100 parts of methanol, 300 parts of vinyl chloride, 20 parts of vinyl acetate, 10 parts of acrylic acid, 1 part of azobisisobutyronitrile, and 10 parts of n-dodecyl mercaptan (chain transfer agent) were charged, and the reaction was started by heating to 70°C while stirring. Subsequently, 660 parts of vinyl chloride, 20 parts of vinyl acetate, and 10 parts of acrylic acid were continuously added over 8 hours to carry out the polymerization reaction. The vinyl chloride used was solidified at -30°C. The internal pressure of the polymerization vessel was 0.5 kg / cm³ after 12 hours of reaction. 2When the pressure reached (gauge pressure), the remaining pressure was released and the mixture was cooled. It was then washed three times with 1500 parts of deionized water, filtered, and dried at 50°C for 24 hours to obtain vinyl chloride-vinyl acetate copolymer resin (A3). The obtained vinyl chloride-vinyl acetate copolymer resin (A3) consisted of 96% by mass of vinyl chloride, 2% by mass of vinyl acetate, 2% by mass of acrylic acid, a weight-average molecular weight of 42000, a glass transition temperature of 86°C, and an acid value of 16 mgKOH / g.

[0058] (Synthesis Example 3) (Synthesis of vinyl chloride-vinyl acetate copolymer resin (A4)) In a 6L stainless steel pressure polymerization vessel equipped with a stirrer, thermometer, and nitrogen gas inlet, after purging with nitrogen, 900 parts of deionized water, 1100 parts of methanol, 300 parts of vinyl chloride, 100 parts of vinyl acetate, 10 parts of acrylic acid, 1 part of azobisisobutyronitrile, and 10 parts of n-dodecyl mercaptan (chain transfer agent) were charged, and the reaction was started by heating to 70°C while stirring. Subsequently, 360 parts of vinyl chloride, 240 parts of vinyl acetate, and 20 parts of acrylic acid were continuously added over 8 hours to carry out the polymerization reaction. The vinyl chloride used was solidified at -30°C. The internal pressure of the polymerization vessel was 0.5 kg / cm³ after 12 hours of reaction. 2 When the pressure reached (gauge pressure), the remaining pressure was released and the mixture was cooled. It was then washed three times with 1500 parts of deionized water, filtered, and dried at 50°C for 24 hours to obtain vinyl chloride-vinyl acetate copolymer resin (A4). The obtained vinyl chloride-vinyl acetate copolymer resin (A4) had a composition of 67% by mass of vinyl chloride, 30% by mass of vinyl acetate, 3% by mass of acrylic acid, a weight-average molecular weight of 38000, a glass transition temperature of 69°C, and an acid value of 23 mgKOH / g.

[0059] [Example 1] Phthalocyanine-based blue pigment (9 parts of Lionol Blue FG-7400G (CI Pigment Blue 15:4) manufactured by Toyo Color Co., Ltd.), vinyl chloride-vinyl acetate copolymer resin (A1) ("E15 / 45M" manufactured by Wacker Chemie AG, 84% vinyl chloride units, 15% vinyl acetate units, 1% dicarboxylic acid units, weight-average molecular weight 55000, glass transition temperature 73℃, acid value 3mgKOH / g), vinyl chloride-vinyl acetate copolymer resin (B1) ("Solvine TAO" manufactured by Nisshin Chemical Industry Co., Ltd., 91% by mass vinyl chloride units, 2% by mass vinyl acetate units, 7% by mass vinyl alcohol units, weight-average molecular weight 69000, glass transition temperature 76℃), resin-type dispersant (acid value: 52mgKOH / g) 0.5 parts of the solution, along with 15 parts of ethyl acetate, 20 parts of propyl acetate, and 8 parts of methyl ethyl ketone as solvents, were placed in a 225cc mayonnaise bottle. 100g of 5mmφ glass beads were added, and the mixture was shaken with paint conditioner for 60 minutes to disperse it and prepare a dispersion. Next, 2 parts of vinyl chloride-vinyl acetate copolymer resin (A1), 2 parts of vinyl chloride-vinyl acetate copolymer resin (B1), 3 parts of rosin ester resin (C1) (Harima Chemicals Group Co., Ltd. "Haritack F-85", acid value: 4~12mgKOH / g, softening point: 80~90℃), 1 part of the plasticizer dibutyl sebacate (Taoka Chemical Industry Co., Ltd. "DBS"), 1.5 parts of paraffin wax (Sasol Co., Ltd.), and 10 parts of ethyl acetate, 15 parts of propyl acetate, and 5 parts of methyl ethyl ketone as solvents were added and mixed to obtain ink W1.

[0060] [Examples 2-19, Comparative Examples 1-3] Inks W2-19 (Examples) and X1-X3 (Comparative Examples) were obtained using the same method as in Example 1, except that the raw materials and mixing ratios listed in Table 1 were used. The properties of the raw materials used are as follows. • Vinyl chloride acrylic copolymer resin (B2) (Wacker Chemie AG "E15 / 40A": 84% vinyl chloride units, 16% acrylic acid ester units, weight-average molecular weight 45,000, glass transition temperature 69°C) • Rosin ester resin (C2) (Harima Chemicals Group Co., Ltd.'s "Harima R-80", acid value: 20 mg KOH / g or higher, softening point: 80~90°C), • Rosin ester resin (C3) (Arakawa Chemical Industries, Ltd. "Pensel AZ", acid value: 35-50 mg KOH / g, softening point: 95-105°C), • Rosin ester resin (C4) (Arakawa Chemical Industries, Ltd. "Ester Gum AA-G", acid value: 0.1~7.0 mgKOH / g, softening point: 82~88℃), • Rosin-modified maleic acid resin (C5) (Arakawa Chemical Industries, Ltd. "Marquid No. 5", acid value: 15-25 mg KOH / g, softening point: 140-150°C) • Polyethylene wax (manufactured by BASF) • Plasticizer: Tributyl acetylcitrate (manufactured by Taoka Chemical Industries, Ltd., "ATBC")

[0061] (Characteristic evaluation) The obtained inks W1-19 (Examples) and X1-X3 (Comparative Examples) were evaluated for ink stability, adhesion, abrasion resistance, heat resistance, water abrasion resistance, crack resistance, and printability. The results are shown in Table 1.

[0062] <Ink Stability> For the obtained inks W1-19 (Examples) and X1-X3 (Comparative Examples), the viscosity stability over time was evaluated based on the change in viscosity values ​​before and after 7 days at 40°C (ink viscosity measurement data using a Zahn cup #4 manufactured by Rigosha at an ink liquid temperature of 25°C), and evaluated according to the following evaluation criteria. The practical level is A to C. (Evaluation Criteria) A: The change in viscosity before and after the time period was less than 5 seconds. B: The viscosity change before and after the time period was between 5 seconds and 10 seconds. C: The viscosity change before and after the time period was between 10 seconds and 20 seconds. D: The change in viscosity before and after the time period was 20 seconds or more.

[0063] (Printing with inks W1-19 (example) and X1-X3 (comparative example)) Inks W1-19 (Examples) and X1-X3 (Comparative Examples) were each diluted in a propyl acetate / methyl ethyl ketone = 50 / 50 mixed solvent at an ink temperature of 25°C using a Zaan Cup #3 manufactured by Rigosha for 15 seconds. Then, each was printed on an uncoated paper substrate (basis weight 300 g / m²) using gravure printing. 2 After printing (175 LPI, 25 μm plate depth, laser plate making method, solid plate, printing speed 100 m / min), volatile components were removed in an in-line oven at 60°C to form the printed layer and obtain the printed material relating to the present invention.

[0064] The following physical property tests were performed on the obtained printed materials.

[0065] <Adhesiveness> The surface of the printed layer of the obtained printed material was covered with 15mm wide x 200mm cellophane tape, and the condition of the printed layer after rapidly peeling it off was evaluated according to the following criteria. A, B, and C represent a range that is practically acceptable. Evaluation Criteria A: A 100% area print layer remained on the paper substrate. B: A printed layer covering 80% or more but less than 100% of the paper substrate remained. C: A printed layer covering 50% or more but less than 80% of the paper substrate remained. D: Less than 50% of the printed layer remained on the paper substrate.

[0066] <Abrasion resistance> The obtained printed materials were evaluated using a JSPS-type friction fastness tester manufactured by Tester Industries Co., Ltd. The test conditions were: specimen width: 25 mm, specimen length: 170 mm, load: 500 g, number of reciprocations: 50, and high-quality paper was used as the test paper. A, B, and C represent ranges that are acceptable for practical use. (Evaluation Criteria) A: The ink did not adhere to the rubbed high-quality paper. B: Ink adhered to 30% of the rubbed high-quality paper. C: Ink adhered to 50% of the rubbed surface area of ​​the high-quality paper. D: Ink adhered to the entire surface of the rubbed high-quality paper.

[0067] <Water friction resistance> The obtained printed materials were evaluated using a friction fastness tester of the Japan Society for the Promotion of Science (JSPS) type, manufactured by Tester Sangyo Co., Ltd. The test conditions were: specimen width: 25 mm, specimen length: 170 mm, load: 200 g, number of reciprocations: 5, and cotton cloth with 5 drops of water was used as the backing paper. A, B, and C represent ranges that are acceptable for practical use. (Evaluation Criteria) A: No ink adhered to the cotton cloth that was rubbed. B: Ink adhered to 30% of the surface area of ​​the rubbed cotton cloth. C: Ink adhered to 50% of the surface area of ​​the rubbed cotton cloth. D: Ink adhered to the entire surface of the cotton cloth that was rubbed.

[0068] <Heat resistance> For the obtained printed materials, a heat seal tester was used to measure the thickness of the printed surface against the aluminum foil at a rate of 2.0 kg / cm². 2 The material was pressed with this pressure for 1 second. Afterwards, the adhesion of the ink coating to the aluminum foil was visually evaluated. Note that A, B, and C are within a range that is acceptable for practical use. (Evaluation Criteria) A: The coating on the printed surface did not adhere to the aluminum foil. B: 30% of the coating on the printed surface adhered to the aluminum foil. C: 50% of the coating on the printed surface adhered to the aluminum foil. D: The entire coating on the printed surface was removed from the aluminum foil.

[0069] <Crack resistance (under normal conditions)> The resulting printed material was cut into 100mm squares, and then the laminate was folded at a 90° angle so that the printed layer formed a mountain fold. The appearance of the printed layer at the folded portion was then visually evaluated. A, B, and C represent acceptable levels for practical use. A: No cracks are visible in the printed layer. B: Some cracks are visible in the printed layer, but no peeling of the printed layer is observed. C: Cracks are visible in the printed layer, but no peeling of the printed layer is observed. D: Cracks and peeling of the printed layer are visible.

[0070] <Crack resistance (excessive conditions)> The resulting printed material was cut into 100mm squares, and the laminate was folded 180° so that the printed layer formed a mountain fold. The appearance of the printed layer at the folded portion was then visually evaluated. A, B, and C represent acceptable levels for practical use. A: No cracks are visible in the printed layer. B: Some cracks are visible in the printed layer, but no peeling of the printed layer is observed. C: Cracks are visible in the printed layer, but no peeling of the printed layer is observed. D: Cracks and peeling of the printed layer are visible.

[0071] <Printability (Plate Coverage)> For inks W1-19 (examples) and X1-X3 (comparative examples), the area of ​​plate cover in non-image areas on the plate after 60 minutes of idle operation was evaluated. A, B, and C represent ranges that are practically acceptable. A: The area of ​​image overlap is 0% or more but less than 5% of the non-image area. B: The area of ​​image overlap is 5% or more but less than 10% of the non-image area. C: The area of ​​image overlap is 10% or more but less than 20% of the non-image area. D: The area of ​​image bleed is 20% or more but less than 50% of the non-image area.

[0072] [Table 1-1]

[0073] [Table 1-2]

[0074] Comparative Example 1, Comparative Example 2, and Comparative Example 3, which do not contain a vinyl chloride resin (A) having an acid value, were unable to achieve any of the following properties: adhesion, abrasion resistance, water abrasion resistance, heat resistance, ink stability, crack resistance, and printability. In contrast, Examples 1 to 19, which are gravure inks for paper substrates containing a vinyl chloride resin and a rosin resin, characterized in that the vinyl chloride resin contains a vinyl chloride resin (A) having an acid value, and the rosin resin is a gravure ink for paper substrates having an acid value, all exhibited performance at or above a level that poses no practical problems in terms of adhesion, abrasion resistance, water abrasion resistance, heat resistance, ink stability, crack resistance, and printability. In other words, the present invention demonstrates that it is possible to provide a gravure ink for paper substrates that solves all the problems.

Claims

1. A gravure ink for paper substrates, comprising a vinyl chloride resin and a rosin resin, A gravure ink for paper substrates, wherein the vinyl chloride resin contains a vinyl chloride resin (A) having an acid value, and the rosin resin also has an acid value.

2. The gravure ink for paper substrates according to claim 1, wherein the vinyl chloride resin further comprises a vinyl chloride resin (B) that does not have an acid value.

3. The gravure ink for paper substrates according to claim 1 or 2, wherein the acid value of the rosin-based resin is 30 mg KOH / g or less.

4. A gravure ink for paper substrates according to claim 1 or 2, wherein the mass ratio of the total mass of a vinyl chloride resin (A) having an acid value and a vinyl chloride resin (B) not having an acid value to the mass ratio of the rosin resin is 51:49 to 99:

1.

5. Furthermore, the gravure ink for paper substrates according to claim 1 or 2, further comprising a resin-type dispersant.

6. Furthermore, the gravure ink for paper substrates according to claim 1 or 2, further comprising a plasticizer.

7. The gravure ink for paper substrates according to claim 1 or 2, wherein the rosin-based resin includes a rosin ester resin.

8. Furthermore, the gravure ink for paper substrates according to claim 1 or 2, further comprising paraffin wax.

9. A printed article having a printed layer formed on a paper substrate using the gravure ink for paper substrates described in claim 1 or 2.

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