Ink composition for ultraviolet laser marking, printed material using the same, and method for recycling printed material

Abstract

To provide an ultraviolet laser marking composition with reduced chlorine-based resin content that achieves a packaging material having superior printability by ultraviolet laser and superior transparency, and also exhibits superior adhesion to a substrate, a printed material using the same, and a method for recycling the printed material.SOLUTION: An ink composition for ultraviolet laser marking comprises at least zinc oxide particles, a urethane resin, and a chlorinated polyolefin resin. The chlorine content in the total resin solids in the ink composition is 1.5 mass% or less.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to an ultraviolet laser marking ink composition used for a flexible packaging film packaging material used for various foods, daily necessities, pharmaceuticals, etc., a printed matter using the composition, and a recycling method of the printed matter.

Background Art

[0002] When printing expiration dates, lot numbers, etc. displayed on packaging packages for foods, daily necessities, pharmaceuticals, etc., inkjet, thermal printing, etc. are mainly used as printers. However, in these methods, there are problems such as ink clogging and consumption of ink ribbons, so there is a problem of the necessity of maintenance and high cost.

[0003] As a new printing method, a method of irradiating laser light for marking is spreading. Since printing by laser does not use ink, ink clogging is eliminated. In addition, consumables such as ink ribbons are not required, and since the printing remains semi-permanently, there is no longer a concern that the printing will disappear due to peeling or the like.

[0004] As types of laser light, infrared lasers and carbon dioxide lasers are known, but these are easily absorbed by transparent base films and the films are easily damaged. In recent years, printing by irradiating laser light in the ultraviolet region with a shorter wavelength than infrared lasers and carbon dioxide lasers has spread, and packaging materials that can be used in the ultraviolet region are required.

[0005] Packaging materials used for ultraviolet laser marking are mainly printed on the coated surface of white ink (see, for example, Patent Document 1). However, in recent years, the diversification of packaging materials has advanced, and there is a demand for a packaging material that has excellent transparency that allows the contents to be confirmed at a glance and can be laser marked.

[0006] Furthermore, in response to the trend of the times, such as the construction of a circular society that reduces substances that can have an adverse impact on the human body or the environment, as represented by the Sustainable Development Goals, regulations regarding packaging materials that use plastic have been becoming stricter globally. In particular, in recent years, there has been a demand for stricter regulations on the components used in packaging materials and their migration into food. Additionally, the movement towards plastic reduction has been accelerating, and the demand for recyclability of packaging materials has been increasing. Therefore, in the development of products related to packaging materials, including inks, it has become necessary to design packaging material constituent materials using materials that ensure safety to the human body or the environment.

[0007] Among them, vinyl chloride-vinyl acetate copolymer is a substance that is a concern as an inhibitor of the recycling of packaging materials for the following reasons (a) and (b).

[0008] (a) Chlorine-based resins such as vinyl chloride can cause corrosion of equipment or piping due to the elimination of hydrogen chloride and the generation of hydrochloric acid in the thermal decomposition process of recycling.

[0009] (b) In thermal recycling, which reuses the energy generated when waste is incinerated, when chlorine-based resins are incinerated, environmental hormones such as dioxins can be emitted.

[0010] Therefore, in the future, the development of environmentally friendly materials, such as chlorine-free chlorine-based resin-free materials, is required. However, in such environmentally friendly materials, it is difficult to satisfy various physical properties such as the dispersibility of the ink composition and the adhesion to the film.

Prior Art Documents

Patent Documents

[0011]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0012] The present invention aims to provide an ultraviolet laser marking composition that can achieve excellent printability and transparency with an ultraviolet laser in a composition with reduced chlorine-based resin, and has excellent adhesion to a substrate, a printed matter using the same, and a recycling method for the printed matter. Further, since the present invention is a composition with reduced chlorine-based resin, it aims to provide an ultraviolet laser marking composition capable of improving the recyclability of a packaging material using the laser marking composition, a printed matter using the same, and a recycling method for the printed matter.

Means for Solving the Problems

[0013] As a result of intensive studies to solve the above-described problems, the present inventors have found that by using a specific metal oxide and a resin, it is possible to achieve printability, film transparency, and excellent adhesion to a substrate in a material with reduced chlorine-based resin.

[0014] That is, the present invention relates to an ultraviolet laser marking ink composition containing at least zinc oxide particles, a urethane resin, and a chlorinated polyolefin resin, and having a chlorine content in the total resin solid content in the ink composition of 1.5% by mass or less.

[0015] The present invention also relates to a printed matter or laminate obtained by printing the above ultraviolet laser marking composition on a substrate.

[0016] Furthermore, the present invention relates to a recycling method for melting and reusing the above printed matter or laminate, and a recycled material using the printed matter.

Effects of the Invention

[0017] Conventionally, when maintaining high ultraviolet shielding properties, the transparency of visible light decreases. In contrast, the present invention provides an ultraviolet shielding film that maintains high blocking properties against ultraviolet rays and has higher transparency to visible light, and a laminate using the film.

Best Mode for Carrying Out the Invention

[0018] The present invention will be described in detail. In the following description, all of the "composition" and "ink composition" refer to the "ink composition for ultraviolet laser marking". Also, all of the "parts" refer to "parts by mass".

[0019] (Ink composition) The laser marking composition of the present invention contains at least zinc oxide particles, a urethane resin, and a chlorinated polyolefin resin. (Zinc oxide particles) As the zinc oxide, those having an average particle diameter of 5 to 200 nm, preferably 10 to 150 nm, and more preferably 15 to 100 nm can be used. In order to enhance the transparency of the substrate (film substrate), a smaller particle diameter is preferred.

[0020] The zinc oxide used in the present invention is preferably 5 to 30% by mass based on the total mass of the ink composition finally adjusted with solvents. In order to enhance the printability by ultraviolet rays and the ultraviolet shielding effect, it is preferable to increase the content ratio of zinc oxide.

[0021] The binder resin used in the composition is not particularly limited, and a binder resin commonly used in liquid inks applied to printing methods using printing plates, such as gravure inks or flexographic inks, can be used. Examples of the resin include, for example, polyurethane resin, ethylene-vinyl acetate copolymer resin, vinyl acetate resin, polyamide resin, acrylic resin, polyester resin, alkyd resin, polyvinyl chloride resin, rosin-based resin, rosin-modified maleic acid resin, ketone resin, cyclized rubber, chlorinated rubber, polyvinyl butyral resin, petroleum resin, and the like. These resins can be used alone or in combination of two or more. Among them, since it is excellent in adhesiveness to the film substrate, blocking resistance, laminating suitability, etc., it is preferable to use a polyurethane resin as the main binder resin. When using a urethane resin as the main binder, the proportion of the urethane resin is preferably 50% by mass or more, preferably 60% by mass or more, preferably 70% by mass or more, preferably 80% or more, and preferably 90% or more based on the total amount of the resin in the ink.

[0022] The polyurethane resin is not particularly limited as long as it is a polyurethane resin obtained by reacting a polyol and a polyisocyanate. As the polyol, a polyurethane resin based on a polyether polyol as a raw material is preferably used, and the content ratio of the polyether polyol is preferably in the range of 1 to 30 parts by mass of a polyether polyol having a number average molecular weight of 100 to 3500 with respect to 100 parts by mass of the polyurethane resin. Details will be described later, but examples of the polyether polyol resin include polyether polyols that are polymers or copolymers of ethylene oxide, propylene oxide, tetrahydrofuran, and the like. Specifically, known and general-purpose ones such as polyethylene glycol resin, polypropylene glycol resin, and polytetramethylene glycol resin may be used. By containing the polyether resin within the above range, the adhesion to the film is significantly improved, and as a result, the blocking resistance and laminating strength are excellent.

[0023] When the number average molecular weight of the polyether polyol resin, which is a constituent component of the polyurethane resin used in the composition, is less than 100, the film of the polyurethane resin tends to become hard, and in particular, the adhesiveness to the polyester film deteriorates. When the number average molecular weight is greater than 3500, the film of the polyurethane resin tends to become fragile and the blocking resistance of the film deteriorates. When the ratio of the polyether polyol is less than 1 part by mass with respect to 100 parts by mass of the polyurethane resin, the solubility of the urethane resin in ketone, ester, and alcohol solvents deteriorates. Also, the redissolvability of the film in the solvent deteriorates, and the tone reproducibility of the printed matter is poor. Also, when it exceeds 30 parts by mass, the blocking resistance tends to be inferior.

[0024] As the combined polyol optionally used in the polyurethane resin used in the composition, various known polyols generally used in the production of polyurethane resins can be used, and one or more of them may be used in combination.For example, polyether polyols of polymers or copolymers such as methylene oxide, ethylene oxide, tetrahydrofuran (1); saturated or unsaturated low molecular weight polyols such as ethylene glycol, 1,2-propanediol, 1,3-propanediol, 2-methyl-1,3-propanediol, 2-ethyl-2-butyl-1,3-propanediol, 1,3-butanediol, 1,4-butanediol, neopentyl glycol, pentanediol, 3-methyl-1,5-pentanediol, hexanediol, octanediol, 1,4-butynediol, 1,4-butylene diol, diethylene glycol, triethylene glycol, dipropylene glycol, glycerin, trimethylolpropane, trimethylolethane, 1,2,6-hexanetriol, 1,2,4-butanetriol, sorbitol, pentaerythritol (2); polyester polyols (3) obtained by dehydration condensation or polymerization of these low molecular weight polyols (2) with polycarboxylic acids such as adipic acid, phthalic acid, isophthalic acid, terephthalic acid, maleic acid, fumaric acid, succinic acid, oxalic acid, malonic acid, glutaric acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, trimellitic acid, pyromellitic acid or their anhydrides; polyester polyols (4) obtained by ring-opening polymerization of cyclic ester compounds such as lactones such as polycaprolactone, polyvalerolactone, poly(β-methyl-γ-valerolactone); polycarbonate polyols (5) obtained by reaction of the above low molecular weight polyols (2) etc. with, for example, dimethyl carbonate, diphenyl carbonate, ethylene carbonate, phosgene etc.; polybutadiene glycols (6); glycols (7) obtained by adding ethylene oxide or propylene oxide to bisphenol A; acrylic polyols (8) obtained by copolymerizing one or more hydroxyethyl, hydroxypropyl acrylate, hydroxybutyl acrylate etc. in one molecule, or their corresponding methacrylic acid derivatives etc. with, for example, acrylic acid, methacrylic acid or their esters, and the like.

[0025] Among the polyester polyols (3), the polymeric diol obtained from diols (glycols) and dibasic acids can have up to 5 mol% of the diols replaced with the low molecular weight polyols (2) having three or more hydroxyl groups.

[0026] Examples of the diisocyanate compound used for the polyurethane resin in the composition include various known aromatic diisocyanates, aliphatic diisocyanates, alicyclic diisocyanates, etc. generally used in the production of polyurethane resins. 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, lysine diisocyanate, cyclohexane-1,4-diisocyanate, xylylene diisocyanate, isophorone diisocyanate, dimer diisocyanate, dicyclohexylmethane-4,4'-diisocyanate, 1,3-bis(isocyanatomethyl)cyclohexane, methylcyclohexane diisocyanate, norbornane diisocyanate, m-tetramethylxylylene diisocyanate, 4,4-diphenylmethane diisocyanate, tolylene diisocyanate, bis-chloromethyl-diphenylmethane-diisocyanate, 2,6-diisocyanate-benzyl chloride, and dimer diisocyanate obtained by converting the carboxyl group of dimer acid into an isocyanate group, etc. These diisocyanate compounds can be used alone or in admixture of two or more.

[0027] As the chain extender used in the polyurethane resin in the composition, in addition to ethylenediamine, propylenediamine, hexamethylenediamine, diethylenetriamine, triethylenetetramine, isophoronediamine, dicyclohexylmethane-4,4'-diamine, etc., amines having a hydroxyl group in the molecule such as 2-hydroxyethylethylenediamine, 2-hydroxyethylpropyldiamine, 2-hydroxyethylpropylenediamine, di-2-hydroxyethylethylenediamine, di-2-hydroxyethylenediamine, di-2-hydroxyethylpropylenediamine, 2-hydroxypyrropylethylenediamine, di-2-hydroxypyrropylethylenediamine, di-2-hydroxypropylethylenediamine can also be used. These chain extenders can be used alone or in combination of two or more.

[0028] Also, as a terminal blocking agent for the purpose of terminating the reaction, a monohydric active hydrogen compound can be used. Examples of such compounds include dialkylamines such as di-n-butylamine and alcohols such as ethanol and isopropyl alcohol. Furthermore, especially when it is desired to introduce a carboxyl group into the polyurethane resin, amino acids such as glycine and L-alanine can be used as the reaction terminator. These terminal blocking agents can be used alone or in combination of two or more.

[0029] The polyurethane resin used in the composition is obtained, for example, by reacting polypropylene glycol and a combined polyol with a diisocyanate compound at a ratio where the isocyanate groups are in excess to obtain a prepolymer with terminal isocyanate groups, and then reacting the resulting prepolymer in a suitable solvent, i.e., ester solvents such as ethyl acetate, propyl acetate, butyl acetate, etc., which are commonly used as solvents for non-toluene-based gravure inks; ketone solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone, etc.; alcohol solvents such as methanol, ethanol, isopropyl alcohol, n-butanol, etc.; hydrocarbon solvents such as methyl cyclohexane, ethyl cyclohexane, etc.; or a mixed solvent of these, by a two-step method of reacting with a chain extender and / or a terminal blocker, or by a one-step method of reacting polypropylene glycol, a combined polyol, a diisocyanate compound, a chain extender and / or a terminal blocker all at once in a suitable solvent among the above. Among these methods, to obtain a uniform polyurethane resin, it is preferably produced by the two-step method. Also, when producing the polyurethane resin by the two-step method, it is preferable to react so that the total (equivalent ratio) of the amino groups of the chain extender and / or the terminal blocker is in the ratio of 1 / 0.9 to 1.3. When the equivalent ratio of the isocyanate group to the amino group is less than 1 / 1.3, the chain extender and / or the terminal blocker may remain unreacted, and the polyurethane resin may turn yellow or an odor may occur after printing.

[0030] The weight average molecular weight of the polyurethane resin thus obtained is preferably in the range of 15,000 to 100,000 and has a glass transition point (Tg) of -45 to -10 °C from the viewpoint of obtaining adhesion to the film substrate of the laminate ink composition and scratch resistance. More preferably, it is in the range of a weight average molecular weight of 20,000 to 60,000. When the weight average molecular weight of the polyurethane resin is less than 15,000, the blocking resistance of the resulting ink composition, the strength of the printed film, and the oil resistance tend to be low. When it exceeds 100,000, the viscosity of the resulting ink composition tends to be high, the smoothness of the surface of the printed film decreases, and the gloss tends to be low.

[0031] From the perspective of ensuring sufficient adhesion of the composition to the printing substrate, the content of the polyurethane resin used in the composition is preferably 4% by mass or more, and preferably 25% by mass or less, more preferably in the range of 6 - 15% by mass, based on the total mass of the composition finally adjusted with solvents, from the viewpoints of appropriate composition viscosity and work efficiency during composition production and printing.

[0032] The polyurethane resin used in the composition can be used without particular limitation as long as it has the aforementioned composition. Among these, those containing an active hydrogen-containing functional group, such as a hydroxyl group, a primary or secondary amino group, etc., in the urethane resin are preferred because the cross-linking between the urethane resin and the blocked isocyanate proceeds smoothly and the resulting film (printing ink layer) becomes strong. Even if the urethane resin does not contain an active hydrogen-containing functional group, heating the ink layer at a high temperature can obtain the same results as when using a urethane resin containing active hydrogen.

[0033] (Chlorinated polyolefin resin) The composition of the present invention contains a chlorinated polyolefin resin. By containing a chlorinated polyolefin resin, the adhesion of the ink composition to treated and untreated substrate films can be improved. Among them, excellent adhesion can be obtained even for polyolefin-based films that are prone to poor adhesion, so excellent adhesion can be achieved regardless of the type of film.

[0034] As the chlorinated polyolefin resin, various known chlorinated polyolefin resins can be used, and those that dissolve in organic solvents are preferred. The structure of the polyolefin resin in the chlorinated polyolefin resin is not particularly limited. For example, resins containing homopolymers or copolymers of α-olefin-based unsaturated hydrocarbons such as polypropylene, poly-1-butene, and poly-4-methyl-1-pentene are preferred. Among them, those containing a polypropylene structure (i.e., a chlorinated polypropylene structure) are particularly preferred.

[0035] The chlorinated polyolefin resin may be a modified product. The modified product is not particularly limited. For example, the modified product of the chlorinated polyolefin is one obtained by graft-polymerizing a polymerizable acrylic compound (such as acrylic acid, methacrylic acid or their alkyl esters) or an unsaturated polycarboxylic acid (such as maleic acid, maleic anhydride, itaconic acid, itaconic anhydride, etc.) to the chlorinated polyolefin, or one obtained by chlorinating a polyolefin graft-polymerized with the above unsaturated polycarboxylic acid, etc.

[0036] The chlorination degree of the chlorinated polyolefin resin is preferably 10% or more and 60% or less, more preferably 20% or more and 55% or less, and still more preferably 30% or more and 50% or less. When the chlorination degree is less than 10%, the chlorinated polypropylene resin tends to have a reduced solubility in solvents. On the other hand, when the chlorination degree exceeds 60%, the ink composition tends to have a reduced adhesion to substrate films such as polyethylene and polypropylene. By having the chlorination degree within the above range, the ink composition can exhibit excellent adhesion to various films.

[0037] The weight average molecular weight of the chlorinated polyolefin resin is preferably 10,000 to 60,000, preferably 11,000 to 50,000, and still more preferably 12,000 to 30,000. It is preferable that the weight average molecular weight is 60,000 or less because the compatibility can be improved.

[0038] The chlorinated polyolefin is used at a content such that the chlorine content contained in the total resin solids in the ink composition is 1.5 mass%.

[0039] Specifically, the content of the chlorinated polypropylene resin is preferably 0.01 mass% or more and 10 mass% or less, preferably 0.05 mass% or more and 8 mass% or less, and still more preferably 0.1 mass% or more and 5 mass% or less of the total amount of the ink composition.

[0040] (Chlorine content) The composition of the present invention has a chlorine content of 1.5% by mass or less based on the total resin solids in the ink composition. Preferably, the chlorine content based on the total resin solids in the ink composition is 1.0% by mass or less, more preferably 0.5% by mass or less, and even more preferably 0.4% by mass or less. Thereby, an environmentally friendly ink with a further reduced chlorine content can be provided.

[0041] Many of the inks currently commonly used are combinations of a polyurethane resin and a chlorine-based resin such as a vinyl chloride-vinyl acetate copolymer resin as a combination of binder resins that can achieve both excellent dispersibility and high film physical properties. In particular, the combination of a chlorine-based resin and a polyurethane resin is very effective for achieving good printability and various physical properties required for laminating inks (adhesion to a substrate, lamination strength, and boil-in-bag suitability). However, when emphasizing the provision of environmentally friendly inks, it is necessary to exclude chlorine-based resins such as vinyl chloride-vinyl acetate copolymer resins. However, when the amount of a chlorine-based resin such as a vinyl chloride-vinyl acetate copolymer resin used is less than a predetermined amount or substantially not used, a problem arises that the suitability as an ink composition deteriorates. However, in the present disclosure, it has been confirmed that by using a urethane resin and a chlorinated polyolefin resin as essential components and defining the ratio of the chlorine content contained in the total resin solids in the ink composition, sufficient ink properties can be imparted even with a composition having a reduced amount of chlorine-based resin.

[0042] The chlorine content is determined by the following formula from the chlorine content in the total resin solids in the ink composition. (Chlorine content contained in the total resin solids in the ink composition) = (Chlorine contained in the total resin solids in the ink composition) / (Mass of the total resin solids in the ink composition) <Other chlorine-based resins> The composition of the present invention may contain a chlorine-based resin (or chlorine-containing resin) other than the chlorinated polyolefin resin, for example, a vinyl chloride-vinyl acetate copolymer resin (solid content), as long as the chlorine content contained in the total resin solids in the ink composition is within a content that results in 1.5% by mass.

[0043] The content of these chlorine-based resins is preferably less than 4.5% by mass, more preferably less than 2.5% by mass, still more preferably less than 1.2% by mass, and even more preferably less than 0.5% by mass based on the total amount of the liquid ink composition (solid content).

[0044] Similarly, the content of the vinyl chloride-vinyl acetate copolymer resin having a hydroxyl group (solid content) is preferably less than 4.5% by mass, more preferably less than 2.5% by mass, still more preferably less than 1.2% by mass, and even more preferably less than 0.5% by mass based on the total amount of the liquid ink composition (solid content).

[0045] However, in order to provide an environmentally friendly ink with a lower chlorine content, it is preferable not to contain these chlorine-based resins.

[0046] The vinyl chloride-vinyl acetate copolymer resin is a copolymer of a vinyl chloride monomer and a vinyl acetate monomer. Therefore, the vinyl chloride-vinyl acetate copolymer resin contains vinyl chloride monomer units and vinyl acetate monomer units. Further, the vinyl chloride-vinyl acetate copolymer resin may contain monomer units of monomers other than vinyl chloride monomer units and vinyl acetate monomer units (other monomers) as necessary. The other monomers are not particularly limited as long as they are copolymerizable with vinyl chloride and vinyl acetate.

[0047] Also, considering the construction of a sustainable recycling-based society (sustainability), it is preferable to use a binder resin made from plant-derived raw materials. Examples of plant-derived raw materials include cellulose-based resins such as cellulose acetate propionate resin and nitrocellulose, polyamide resins using dimer acid or polymerized fatty acid derived from natural oils such as soybean oil, palm oil, and rice bran oil, polycarboxylic acids such as succinic acid, succinic anhydride, adipic acid, azelaic acid, sebacic acid, dimer acid, glutaric acid, malic acid, etc., polyols such as ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, neopentyl glycol, pentylene glycol, 1,10-dodecanediol, dimer diol, isosorbide, etc., polyisocyanates such as 1,5-pentamethylene diisocyanate, dimer diisocyanate, etc., biomass polyurethanes synthesized from plant-derived raw materials, rosin resins, and the like.

[0048] When containing other resins other than urethane resin and chlorinated polyolefin resin, it is preferable to contain 0.1 to 5% by mass of other resins based on the total resin solid content of the ink composition.

[0049] The ink composition may contain various additives such as a pigment dispersant, a leveling agent, an antifoaming agent, a wax, a plasticizer, a fragrance, and a flame retardant.

[0050] As the organic solvent used in the ink composition, various organic solvents can be used, but it is preferable to use organic solvents excluding aromatic organic solvents. For example, ketone solvents such as acetone, methyl ethyl ketone, and methyl isobutyl ketone; ester solvents such as methyl acetate, ethyl acetate, isopropyl acetate, n-propyl acetate, butyl acetate, amyl acetate, ethyl formate, butyl propionate, and propylene glycol monomethyl ether acetate; alcohol solvents such as methanol, ethanol, isopropyl alcohol, n-propanol, inopropanol, n-butanol, and propylene glycol monomethyl ether; glycol ether solvents such as ethylene glycol (mono, di) methyl ether, ethylene glycol (mono, di) ethyl ether, ethylene glycol monopropyl ether, ethylene glycol monoisopropyl ether, monobutyl ether, diethylene glycol (mono, di) methyl ether, diethylene glycol (mono, di) ethyl ether, diethylene glycol monoisopropyl ether, diethylene glycol monobutyl ether, triethylene glycol (mono, di) methyl ether, propylene glycol (mono, di) methyl ether, propylene glycol monopropyl ether, propylene glycol monobutyl ether, and dipropylene glycol (mono, di) methyl ether. These can be used alone or as a mixture of two or more. In recent years, from the perspective of the working environment, it is desirable not to use aromatic solvents such as toluene, xylene, Solvesso #100, and Solvesso #150, or ketone solvents. Among them, from the perspective of solubility in polyurethane resin, a mixed solution containing ethyl acetate, isopropyl alcohol, and normal propyl acetate is more preferable.

[0051] The ink composition can be produced by dissolving and / or dispersing a resin, zinc oxide, etc. in an organic solvent. Specifically, an ink can be produced by manufacturing a dispersion in which zinc oxide is dispersed in an organic solvent with a polyurethane resin, and blending other compounds, etc. as necessary into the obtained dispersion. As the disperser, generally used ones such as a roller mill, ball mill, pebble mill, attritor, sand mill, etc. can be used.

[0052] (Substrate) As the substrate, it is preferable to use a film substrate. The film substrate is, for example, a polyester resin such as polyethylene terephthalate (hereinafter may be referred to as PET), polyethylene naphthalate, polytrimethylene terephthalate, polytrimethylene naphthalate, polybutylene terephthalate, polybutylene naphthalate, etc., a polyamide such as nylon 6, nylon 66, nylon 46, etc., a polyhydroxycarboxylic acid such as polylactic acid, a biodegradable resin such as an aliphatic polyester resin such as poly(ethylene succinate), poly(butylene succinate), etc., a polyolefin such as polypropylene (CPP: unstretched polypropylene film, OPP: biaxially stretched polypropylene film), polyethylene (LLDPE: low density polyethylene film, HDPE: high density polyethylene film), etc., a film made of a thermoplastic resin such as polyimide, polyarylate, polystyrene, polyacrylonitrile, polyvinyl alcohol, ethylene-vinyl alcohol copolymer, etc. or a laminate thereof. Among them, films made of polyethylene terephthalate, polyethylene, and polypropylene can be preferably used.

[0053] Also, as the film substrate, it is also preferable to use a film formed of a material containing a biomass-derived component. Biomass films are sold by various companies, and for example, sheets such as those listed in the list of biomass-certified products described by the Japan Organic Resources Association, a general incorporated foundation, can be used.

[0054] Specifically well-known films are made from ethylene glycol derived from biomass. Ethylene glycol derived from biomass is made from ethanol (biomass ethanol) produced from biomass as a raw material. For example, biomass-derived ethylene glycol can be obtained by a method of producing ethylene glycol via ethylene oxide from biomass ethanol by a conventionally known method or the like. Also, commercially available biomass ethylene glycol may be used. For example, biomass ethylene glycol commercially available from Indiaglycol Co., Ltd. can be preferably used.

[0055] Alternatively, those using biomass raw materials distinguished by the biomass plastic degree defined in ISO 16620 or ASTM D6866 are also on the market. In the atmosphere, radioactive carbon 14C exists at a ratio of 1 in 1012, and this ratio does not change even in carbon dioxide in the atmosphere. Therefore, this ratio does not change even in plants that have fixed this carbon dioxide by photosynthesis. For this reason, the carbon of plant-derived resins contains radioactive carbon 14C. In contrast, the carbon of fossil fuel-derived resins contains almost no radioactive carbon 14C. Therefore, by measuring the concentration of radioactive carbon 14C in the resin with an accelerator mass spectrometer, the content ratio of plant-derived resins in the resin, that is, the biomass plastic degree can be determined. As plant-derived low-density polyethylene, which is a biomass plastic with a biomass plastic degree of 80% or more, preferably 90% or more, defined in ISO 16620 or ASTM D6866, for example, products named "SBC818", "SPB608", "SBF0323HC", "STN7006", "SEB853", "SPB681", etc. manufactured by Braskem can be mentioned, and films using these as raw materials can be preferably used.

[0056] For example, as an alternative to polyethylene terephthalate films using conventional petroleum-based raw materials, films containing biomass polyesters such as biomass polyesters using ethylene glycol derived from biomass as the diol unit and dicarboxylic acids derived from fossil fuels as the dicarboxylic acid unit, and biomass polyethylene terephthalate are known. The dicarboxylic acid unit of the biomass polyester uses dicarboxylic acids derived from fossil fuels. As the dicarboxylic acid, aromatic dicarboxylic acids, aliphatic dicarboxylic acids, and their derivatives can be used without limitation.

[0057] In addition to the above diol component and dicarboxylic acid component, a copolymer polyester obtained by adding a copolymer component as a third component such as at least one polyfunctional compound selected from the group consisting of bifunctional oxycarboxylic acids, polyhydric alcohols having three or more functional groups, polyvalent carboxylic acids having three or more functional groups and / or their anhydrides, and oxycarboxylic acids having three or more functional groups for forming a crosslinked structure may also be used.

[0058] Also, for example, as an alternative to polyolefin-based films using conventional petroleum-based raw materials, biomass polyolefin-based films such as biomass polyethylene-based films containing polyethylene-based resins using ethylene glycol derived from biomass as a raw material, and biomass polyethylene-polypropylene-based films are known.

[0059] The polyethylene-based resin is not particularly limited except that a part of the raw material uses the ethylene glycol derived from biomass, and examples include homopolymers of ethylene, copolymers of ethylene and α-olefins with ethylene as the main component (ethylene-α-olefin copolymers containing 90% by mass or more of ethylene units), etc. These can be used alone or in combination of two or more.

[0060] The biomass film may be a laminate in which a plurality of biomass films are laminated, or a laminate of a conventional petroleum-based film and a biomass film.

[0061] In addition, these films may be either unstretched films or films that have been subjected to stretching treatment, and their manufacturing methods are not limited either. As a stretching treatment method, it is common to melt-extrude a resin by an extrusion film-forming method or the like to form a sheet, and then perform simultaneous biaxial stretching or sequential biaxial stretching. In the case of sequential biaxial stretching, it is common to first perform longitudinal stretching treatment and then perform transverse stretching. Specifically, a method that combines longitudinal stretching using the speed difference between rolls and transverse stretching using a tenter is often used.

[0062] In addition, the thickness of the base film is not particularly limited, but usually it may be in the range of 1 to 500 μm. If necessary, various surface treatments such as flame treatment or corona discharge treatment may be performed on the film surface so that an adhesive layer without defects such as film breakage or repulsion is formed.

[0063] (Printed matter) The printed matter of the present invention is provided with a laser printing layer by applying an ink composition on the above-described film base material. The laser printing layer preferably has a film thickness of 0.5 to 5 μm, and more preferably 1 to 3 μm. Within this range, both printability and transparency can be achieved.

[0064] In addition, the laser printing layer is preferably a coating layer with a coating amount of 2.0 g / m 2 or more. By setting the coating amount to 2.0 g / m 2 or more, the printability and the shielding effect in the ultraviolet region can be improved. The coating amount is preferably 2.5 g / m 2 or more, and more preferably 3.0 g / m 2 or more.

[0065] On the other hand, the upper limit of the coating amount is not particularly limited, but from the viewpoint of the adhesion of the shielding layer, it is preferably 10.0 g / m 2 or less, and preferably 8 g / m 2 or less.

[0066] Since the printed matter of the present invention has a laser printing layer, it can be printed on a transparent base film by the ultraviolet laser marking method described later.

[0067] The wavelength of the ultraviolet laser is mainly absorbed and printed at a wavelength near 355 nm. Generally, compared with the fundamental wavelength laser (IR / 1,064 nm) and the green laser (SHG / 532 nm), the ultraviolet laser has a significantly higher absorption rate to the material, and the irradiated light is efficiently absorbed by the printed surface. Usually, it is printed on a packaging material with ultraviolet absorption near 355 nm such as a white film.

[0068] Therefore, in the measured transmittance value at 355 nm, if the transmittance is 3% or less, even a transparent film can be printed.

[0069] Since the printed matter of the present invention or the laminate described later has a component composed of a base film and a laser printing layer, it has ultraviolet shielding properties. Specifically, the transmittance of the printed matter composed of the film / laser printing layer or the laminate composed of the film / laser printing layer / adhesive layer / film at a wavelength of 300 - 360 nm is 3% or less.

[0070] More specifically, in the printed matter of the present invention, when a polyolefin film with a transmittance of 92% or less at a wavelength of 300 - 360 nm is used, the transmittance of the component composed of the film and the laser printing layer in the printed matter can be 3% or less at a wavelength of 300 - 360 nm. By adjusting the film thickness of the laser printing layer, it can also be 2% or less, 1% or less, and even 0.5% or less.

[0071] The ultraviolet shielding film of the present invention preferably has a transparency (haze) of 20 or less.

[0072] Specifically, when using a polyolefin film with a haze of 2.8 as the film, the haze of the component composed of the film and the laser printing layer in the printed matter using the film can be 20 or less, more preferably 15 or less, still more preferably 10 or less, even more preferably 8.5 or less, and still even more preferably 7 or less.

[0073] The ultraviolet ray shielding film of the present invention can be manufactured by applying an ultraviolet ray shielding ink on the film. Specifically, it can be obtained by printing an ultraviolet ray shielding ink on at least one side of the film. As the printing method, it can be printed by known printing methods such as gravure printing and flexographic printing, but it is particularly preferable to print by the gravure printing method. Also, it may be formed by known coating methods such as spray method, spin coating method, dip method, roll coating method, blade coating method, doctor roll method, doctor blade method, curtain coating method, slit coating method, screen printing method, inkjet method, dispensing method, die coat (die coating) method, direct gravure method, reverse gravure method, flexo method, knife coating method, dot coat method, etc. After applying the ultraviolet ray shielding ink on the film by these methods, the ultraviolet ray shielding film can be obtained by drying or curing by an oven and fixing it as necessary.

[0074] The printed matter of the present invention may have other coating layers and / or vapor deposition layers such as a colored ink layer, a heat-resistant coating layer, a resin layer having barrier properties, a heat-sealing layer, a metal vapor deposition layer, etc. in addition to the laser marking layer on the film.

[0075] For example, by having a colored ink layer, the product name can be displayed, the design property can be enhanced, and the ultraviolet ray shielding effect can be enhanced by the ultraviolet ray absorption effect of the colorant.

[0076] Moreover, by applying other functional coating agents, various functions can be enhanced. As a specific configuration, an example is the structure of a resin layer / film / colored printing layer / ultraviolet ray shielding layer / heat-resistant coating layer having layer / barrier properties by a heat-sealing agent or a cold-sealing agent. However, the lamination order and the types of coating layers are not limited to this.

[0077] (Colored printing layer) The colored printing layer is formed by colored printing ink. The printing ink is used as gravure printing ink or flexographic printing ink, and is roughly classified into organic solvent-based liquid printing ink having an organic solvent as the main solvent and aqueous liquid printing ink having water as the main solvent. In the present invention, either one can be used. Also, there are so-called surface printing ink and back printing ink assuming lamination. In the present invention, either one can be used.

[0078] The mainstream organic solvent-based liquid printing ink has a binder resin, a colorant, an organic solvent, and other additives as required.

[0079] The binder resin and the organic solvent can be the same as those used in the ultraviolet ray shielding ink described above.

[0080] The colorants can include inorganic pigments, organic pigments, and dyes used in general inks, paints, recording agents, etc., and pigments are preferred. Examples of organic pigments include soluble azo-based, insoluble azo-based, azo-based, phthalocyanine-based, halogenated phthalocyanine-based, anthraquinone-based, ansanthrone-based, dianthraquinonyl-based, anthrapyrimidine-based, perylene-based, perinone-based, quinacridone-based, thioindigo-based, dioxazine-based, isoindolinone-based, quinophthalone-based, azomethine azo-based, flavanthrone-based, diketopyrrolopyrrole-based, isoindoline-based, indanthrone-based, carbon black-based pigments, etc. Further, for example, Carmine 6B, Lake Red C, Permanent Red 2B, Disazo Yellow, Pyrazolone Orange, Carmine FB, Chromophthal Yellow, Chromophthal Red, Phthalocyanine Blue, Phthalocyanine Green, Dioxazine Violet, Quinacridone Magenta, Quinacridone Red, Indanthrone Blue, Pyrimidine Yellow, Thioindigo Bordeaux, Thioindigo Magenta, Perylene Red, Perinone Orange, Isoindolinone Yellow, Aniline Black, Diketopyrrolopyrrole Red, daylight fluorescent pigments, etc. can be mentioned. Also, either unacid-treated pigments or acid-treated pigments can be used.

[0081] Examples of inorganic pigments include white inorganic pigments such as titanium oxide, zinc oxide, zinc sulfide, barium sulfate, calcium carbonate, chromium oxide, silica, lithopone, antimony white, gypsum, etc. Among the inorganic pigments, the use of titanium oxide is particularly preferred. Titanium oxide exhibits white color and is preferable in terms of coloring power, hiding power, chemical resistance, and weather resistance. From the viewpoint of printing performance, the titanium oxide preferably has been treated with silica and / or alumina. Examples of inorganic pigments other than white include, for example, aluminum particles, mica, bronze powder, chrome vermilion, lead yellow, cadmium yellow, cadmium red, ultramarine, navy blue, red iron oxide, yellow iron oxide, iron black, zircon. Aluminum is in powder or paste form, but it is preferably used in paste form from the viewpoints of handleability and safety. Whether to use leafing or non-leafing is appropriately selected from the viewpoints of brightness and density.

[0082] The above pigments are preferably contained in an amount sufficient to ensure the density and coloring power of the liquid printing ink, that is, in a proportion of 1 to 60% by mass based on the total mass of the liquid printing ink, and 10 to 90% by mass in terms of the solid content weight ratio in the liquid printing ink. These pigments can be used alone or in combination of two or more.

[0083] In the case of organic solvent-based liquid printing ink, wax, chelate crosslinking agent, extender pigment, leveling agent, defoaming agent, plasticizer, infrared absorber, ultraviolet absorber, fragrance, flame retardant, etc. can also be included as required.

[0084] In the liquid printing ink used for the colored printing layer, considering the construction of a sustainable recycling-oriented society (sustainability) that should continue to develop, it is preferable to use a liquid printing ink made from plant-derived raw materials. Commercially available products can also be used as biomass liquid printing ink. As commercially available products, inks described in the Japan Organic Resources Association can be used.

[0085] (Resin layer with barrier properties) Examples of the resin layer with barrier properties include the method of laminating a film with barrier properties and the method of applying a barrier coating agent to form a coating film layer. However, the method of applying a barrier coating agent to form a coating film layer is simple and preferable.

[0086] Examples of barrier coating agents include coating agents containing polymers such as polyvinyl alcohol (PVOH), ethylene vinyl alcohol (EVOH), polysaccharides, acrylic acid- or methacrylic acid-based polymers, starch or starch derivatives, cellulose nanofibers (CNF), nanocrystalline cellulose (NCC), chitosan, or other cellulose derivatives, hemicellulose, polyvinylidene chloride (PVDC), or coating agents containing inorganic fine particles in these polymers, such as silica, alumina, aluminum flakes, glass flakes, hydrous silicates (such as phyllosilicate minerals), kaolinite-serpentine group clay minerals (such as halloysite, kaolinite, endellite, dickite, nacrite, etc., antigorite, chrysotile, etc.), pyrophyllite-talc group (such as pyrophyllite, talc, kerolite, etc.), smectite group clay minerals (such as montmorillonite, beidellite, nontronite, saponite, hectorite, sauconite, stibnite, etc.), vermiculite group clay minerals (such as vermiculite, etc.), mica or mica group clay minerals (such as mica such as muscovite, phlogopite, etc., margarite, tetrasilicic mica, teniolite, etc.), chlorite group (such as cookeite, sudorite, clinochlore, chamosite, nimite, etc.), hydrotalcite, plate-like barium sulfate, boehmite, polyaluminum phosphate, and other plate-like inorganic compounds are known.

[0087] In the present invention, known barrier coating agents can be used without particular limitation. As known barrier coating agents, those of the "Sunbar" series manufactured by Sankyo Chemical Co., Ltd. and polyester-based barrier coating agents described in Patent No. 5617831 can be used.

[0088] (Heat-resistant coating layer) The heat-resistant coating layer is a coating film layer of a heat-resistant coating agent. As the heat-resistant coating agent, materials having a cellulose skeleton, a benzene ring, an isocyanuric skeleton, and an alicyclic skeleton are effective. Specifically, cellulose derivatives such as nitrocellulose, cellulose acetate, cellulose propionate, and cellulose butyrate, benzene rings such as phthalic acid, naphthalenedicarboxylic acid, and EO adducts of bisphenol A, and / or polyester resins having an alicyclic skeleton such as cyclopentanediol and dimethyloltricyclodecane, or aromatic isocyanates such as diphenylmethane diisocyanate, toluene diisocyanate, xylene diisocyanate, and naphthalene diisocyanate, alicyclic isocyanates such as isophorone diisocyanate and norbornene diisocyanate, and / or urethane resins obtained by bonding isocyanuric triisocyanate with polyol and / or tris(2-hydroxyethyl)isocyanurate can be mentioned. Also, polyisocyanates using the aforementioned isocyanates may be used as curing agents. On the other hand, compounds having a benzene ring and an unsaturated double bond such as styrene and phenoxydiethylene glycol acrylate, and / or compounds having an alicyclic structure and an unsaturated double bond such as isobornyl acrylate and dicyclopentanyl acrylate, and radical copolymers such as (meth)acrylate can be mentioned.

[0089] In addition, the heat-resistant coating agent may be colored. The coloring agent is not particularly limited. For example, the liquid printing ink used in the present invention contains a coloring agent and can be used as a liquid printing ink containing a coloring agent used for design printing or the like for the purpose of imparting cosmetic properties or the like. Examples of the coloring agent include inorganic pigments, organic pigments, and dyes used in general inks, paints, and recording agents, and pigments are preferred. Examples of the organic pigment include soluble azo-based, insoluble azo-based, azo-based, phthalocyanine-based, halogenated phthalocyanine-based, anthraquinone-based, anthraquinone-based, dianthraquinonyl-based, anthrapyrimidine-based, perylene-based, perinone-based, quinacridone-based, thioindigo-based, dioxazine-based, isoindolinone-based, quinophthalone-based, azomethine azo-based, flavanthrone-based, diketopyrrolopyrrole-based, isoindoline-based, indanthrone-based, carbon black-based pigments, and the like. Further, for example, carmine 6B, lake red C, permanent red 2B, disazo yellow, pyrazolone orange, carmine FB, chromophthal yellow, chromophthal red, phthalocyanine blue, phthalocyanine green, dioxazine violet, quinacridone magenta, quinacridone red, indanthrone blue, pyrimidine yellow, thioindigo Bordeaux, thioindigo magenta, perylene red, perinone orange, isoindolinone yellow, aniline black, diketopyrrolopyrrole red, daylight fluorescent pigments, and the like can be mentioned. Also, either unacid-treated pigments or acid-treated pigments can be used.

[0090] There is no particular limitation on the inorganic pigment, and it is appropriately selected from the same ones as the inorganic pigments used in the colored printing layer described above.

[0091] (Layer by heat-sealing agent or cold-sealing agent) The layer by the heat-sealing agent or cold-sealing agent is provided by coating a solution of a thermoplastic elastomer such as polyester, vinyl chloride acetate resin, EVOH, acrylic resin, polyolefin resin, or rubber resin. The coating can be applied to the entire surface or partially, and the film thickness of the solid content is 1 μm to 5 μm.

[0092] (Vapor deposition layer) The vapor deposition layer is provided by vapor-depositing a metal such as aluminum on the film.

[0093] (Laminated laminate using the above printing) The laminate of the present invention is a laminate obtained by laminating a plurality of base materials, and at least one of the base materials has the printed matter of the present invention. The base materials can be laminated via an adhesive layer or by extrusion lamination.

[0094] As a more specific configuration of the laminate, (1) Substrate film 1 / Laser printing layer / Adhesive layer 1 / Sealant film (2) Substrate film 1 / Laser printing layer / Adhesive layer 1 / Substrate film 2 (3) Substrate film 1 / Laser printing layer / Adhesive layer 1 / Unstretched metal vapor deposition film (4) Substrate film 1 / Laser printing layer / Adhesive layer 1 / Stretched metal vapor deposition film (5) Transparent stretched vapor deposition film / Laser printing layer / Adhesive layer 1 / Sealant film (6) Substrate film 1 / Laser printing layer / Adhesive layer 1 / Substrate film 2 / Adhesive layer 2 / Sealant film (7) Substrate film 1 / Laser printing layer / Adhesive layer 1 / Stretched metal vapor deposition film / Adhesive layer 2 / Sealant film (8) Substrate film 1 / Laser printing layer / Adhesive layer 1 / Transparent stretched vapor deposition film / Adhesive layer 2 / Sealant film (9) Substrate film 1 / Laser printing layer / Adhesive layer 1 / Metal layer / Adhesive layer 2 / Sealant film (10) Substrate film 1 / Laser printing layer / Adhesive layer 1 / Substrate film 2 / Adhesive layer 2 / Metal layer / Adhesive layer 3 / Sealant film (11) Substrate film 1 / Laser printing layer / Adhesive layer 1 / Metal layer / Adhesive layer 2 / Substrate film 2 / Adhesive layer 3 / Sealant film Examples include, but are not limited to, the above. Note that the above "base film 1 / laser printing layer" corresponds to the above "printed matter". For example, a configuration in which an ultraviolet shielding layer is provided on the base film 2 may also be used.

[0095] In addition, the laminate may further have other coating layers and / or vapor deposition layers such as a colored ink layer, a heat-resistant coating layer, a resin layer having barrier properties, a heat-seal layer, and a metal vapor deposition layer.

[0096] (Adhesive layer) As the adhesive layer, a known adhesive for film lamination can be appropriately used. When laminating by extrusion lamination, a known anchor coating agent for extrusion lamination can be appropriately used as an adhesion aid. When using a material having gas barrier properties as these adhesives or anchor coating agents, a laminate having particularly excellent barrier properties can be obtained.

[0097] Particularly preferably, as an adhesive having excellent gas barrier properties, it refers to one that satisfies at least one of the conditions that the oxygen barrier property of the cured coating film of the adhesive applied at 3 g / m2 (solid content) is 300 cc / m2 / day / atm or less, or the water vapor barrier property is 120 g / m2 / day or less. Commercially available products include the "PASLIM" series such as PASLIM VM001 and PASLIM J350X manufactured by DIC Corporation, and "Maxieve" manufactured by Mitsubishi Gas Chemical Company.

[0098] The adhesive layer can be made of a known material without particular limitation, but preferably contains a cured product of a polyol and an isocyanate compound. When these polyols and / or isocyanate compounds contain biomass-derived components, a laminate with a high biomass content can be obtained, and the environmental load can be reduced.

[0099] In addition, it may contain an adhesion promoter, an acid anhydride, a compound having an oxygen scavenging function, a tackifier, a gas barrier adhesive, stabilizers (such as antioxidants, heat stabilizers, ultraviolet absorbers, etc.), plasticizers, antistatic agents, lubricants, antiblocking agents, colorants, crystal nucleating agents, etc. These various additives may be added in advance to either one or both of the polyol composition (A) and the polyisocyanate composition (B), or may be added when the polyol composition (A) and the polyisocyanate composition (B) are mixed.

[0100] Also, the gas barrier adhesive to be used may be in either a solvent-based or solvent-free form. When the gas barrier adhesive to be used is solvent-based, the adhesive of the present invention is applied onto the printed layer surface printed on the first substrate using a roll such as a gravure roll, and after volatilizing the organic solvent by heating in an oven or the like, the other substrate is laminated to obtain the laminate of the present invention. It is preferable to perform an aging treatment after lamination. The aging temperature is preferably from room temperature to 80°C, and the aging time is preferably from 12 to 240 hours.

[0101] When the gas barrier adhesive to be used is solvent-free, the adhesive of the present invention preheated to about 40°C to 100°C is applied onto the printed layer surface printed on the first substrate using a roll such as a gravure roll, and then the other substrate is immediately laminated to obtain the laminate of the present invention. It is preferable to perform an aging treatment after lamination. The aging temperature is preferably from room temperature to 70°C, and the aging time is preferably from 6 to 240 hours.

[0102] When the gas barrier adhesive to be used is used as an adhesion assistant, the adhesion assistant of the present invention is applied onto the printed layer surface printed on the first substrate using a roll such as a gravure roll, and after volatilizing the organic solvent by heating in an oven or the like, the polymer material melted by an extruder is laminated to obtain the laminate of the present invention. As the polymer material to be melted, polyolefin resins such as low-density polyethylene resin, linear low-density polyethylene resin, and ethylene-vinyl acetate copolymer resin are preferable. The aging temperature is preferably from room temperature to 70°C, and the aging time is preferably from 6 to 240 hours.

[0103] The coating amount of the gas barrier adhesive to be used is adjusted as appropriate. In the case of a solvent-based adhesive, for example, the solid content is 1 g / m 2 or more and 10 g / m 2 or less, preferably 2 g / m 2 or more and 5 g / m 2 or less for adjustment. In the case of a solventless adhesive, the coating amount of the adhesive is, for example, 1 g / m 2 or more and 5 g / m 2 or less, preferably 1 g / m 2 or more and 3 g / m 2 or less.

[0104] When the adhesive is used as an adhesion aid, the coating amount is adjusted as appropriate, but is, for example, 0.03 g / m 2 or more and 2 g / m 2 or less (solid content).

[0105] In addition, in the laminate structure, each film constituting the laminate is preferably composed of as single a main raw material as possible in order to improve the quality of recycled plastic when the laminate is recycled. For example, it is preferable to use a laminated film (sometimes referred to as a monomaterial film) composed only of polyolefin films such as polyethylene films and polypropylene films, and laminate a plurality of these layers as a packaging material.

[0106] For example, when the laminate is composed only of a polyolefin film, it is preferable to provide a heat-resistant coating layer in order to improve heat resistance during heat sealing or the like. In addition, in order to enhance the barrier property, it is preferable to use an adhesive or a coating agent having a barrier property.

[0107] <Packaging material> The printed matter and laminate of the present invention can be used as a multilayer packaging material for protecting foods, pharmaceuticals, and the like. When used as a multilayer packaging material, the layer structure can vary depending on the contents, the use environment, and the use form.

[0108] The packaging material of the present invention is obtained, for example, by using the laminate of the present invention, overlapping the surfaces of the sealant films of the laminate facing each other, and then heat-sealing the peripheral ends thereof. As a bag-making method, the laminate of the present invention is bent or overlapped so that the inner layer surfaces (the surfaces of the sealant films) face each other, and the peripheral ends thereof are heat-sealed, for example, in the form of a side seal type, a two-side seal type, a three-side seal type, a four-side seal type, an envelope pasting seal type, a palm pasting seal type, a pleat-attached seal type, a flat-bottom seal type, a corner-bottom seal type, a gusset type, or other heat-seal types. The packaging material of the present invention can take various forms according to the contents, the use environment, and the use form. A self-standing packaging material (standing pouch) or the like is also possible. As a heat-sealing method, it can be carried out by known methods such as bar sealing, rotary roll sealing, belt sealing, impulse sealing, high-frequency sealing, and ultrasonic sealing.

[0109] After filling the contents into the packaging material of the present invention through its opening, the opening is heat-sealed to produce a product using the packaging material of the present invention. The use of the packaging material is not particularly limited, but the packaging material using the printed matter or laminate of the present invention has high transparency to visible light and also exhibits high blocking properties to ultraviolet rays, and can be suitably used for film packaging applications such as foods, pharmaceuticals, cosmetics, electronic components, infusion packs, and vacuum insulation materials. (Recycled plastic) The printed matter, laminate, and packaging material of the present invention can also be processed by various known recycled plastic processing methods as they are to produce recycled plastic. Since the printed matter, laminate, and packaging material of the present invention have a configuration with a reduced chlorine content in the laser printing layer, they are optimal for recycling as recycled plastic. As an example of a specific embodiment, a production method having a step of separating the laminate of the present invention into the respective base materials or crushing the laminate and packaging material of the present invention, a step of melt-kneading the crushed film pieces, and a step of pelletizing the melt-kneaded kneaded product can be used to obtain recycled plastic.

[0110] For the crusher used during crushing (pulverization), any known crusher may be used, and there is no particular limitation.

[0111] After pulverization, the film pieces are physically blended by melt-kneading, solvent casting blend, latex blend, polymer complex, etc. In particular, the melt-kneading method is common. Examples of the apparatus for kneading include a tumbler, Henschel mixer, rotary mixer, super mixer, ribbon tumbler, V blender, etc. After melt-kneading with such a kneading apparatus, pelletization is performed. For melt-kneading pelletization, it is common to use a single-screw or multi-screw extruder. It may be fed as it is in the form of film pieces, or may be fed after compression and volume reduction treatment with or without heating. Further, in addition to these extruders, a Banbury mixer, roller, co-kneader, blast mill, Brabender Plastograph, etc. can also be used, and these are operated batchwise or continuously. Also, instead of melt-kneading, a method may be used where it is used as a molding resin and melt-kneaded in the heating cylinder of a molding machine.

[0112] <Ultraviolet Laser Marking Method> The ultraviolet laser marking method performs printing by irradiating with a laser in the ultraviolet region, preferably 10 to 380 nm. As the ultraviolet laser, known ones can be used and there is no particular limitation. For example, as those capable of laser irradiation with a wavelength of 355 nm, a third harmonic YAG laser, a third harmonic YVO4 laser, etc. can be mentioned. Printing with an ultraviolet laser can produce highly visible printing because it causes the laser printing layer itself to develop color, and has the advantage that the substrate is not thermally damaged by ultraviolet irradiation.

Examples

[0113] The present invention will be described more specifically by way of examples. Hereinafter, both "parts" and "%" are based on mass. In addition, the measurement of the number average molecular weight (polystyrene conversion) by GPC (gel permeation chromatography) in the present invention was performed under the following conditions using an HLC8220 system manufactured by Tosoh Corporation.

[0114] Separation column: 4 TSKgel GMHHR-N columns manufactured by Tosoh Corporation. Column temperature: 40°C. Mobile phase: Tetrahydrofuran manufactured by Wako Pure Chemical Industries, Ltd. Flow rate: 1.0 ml / min. Sample concentration: 1.0 mass%. Sample injection volume: 100 microliters. Detector: Differential refractometer. Also, the glass transition temperature (Tg) was measured by scanning under differential atmosphere conditions using a cooling device in the temperature range of -80 to 450°C at a heating rate of 10°C / min.

[0115] (Preparation of polyurethane resin solution P) Into a four-necked flask equipped with a stirrer, thermometer, reflux condenser, and nitrogen gas inlet tube, 84.5 parts of neopentyl glycol adipate diol (hydroxyl value: 56.6 mg KOH / g), 15.5 parts of polyethylene glycol (hydroxyl value: 278 mg KOH / g), and 27.55 parts of isophorone diisocyanate were charged and reacted at 90°C for 10 hours under a nitrogen stream to produce a urethane prepolymer with an isocyanate group content of 2.84% by weight. Then, 68.7 parts of ethyl acetate was added thereto to form a uniform solution of the urethane prepolymer. Next, the urethane prepolymer solution was added to a mixture consisting of 7.83 parts of isophoronediamine, 0.11 part of di-n-butylamine, 136.8 parts of ethyl acetate, and 110.7 parts of isopropyl alcohol, and the mixture was stirred and reacted at 45°C for 5 hours to obtain polyurethane resin solution P.

[0116] The obtained polyurethane resin solution P had a resin solid content concentration of 30.4% by weight and an Mw of the resin solid of 54,000. It contains 11.4% by mass of polyethylene glycol (15.5 parts) as a polyether polyol in the polyurethane resin (total 137.76 parts).

[0117] (Example 1) The adjusted polyurethane resin P (solid content 30%), rosin resin solution (solid content 50%), chlorinated polyolefin resin solution (solid content 60%, chlorine content 31%), zinc oxide with an average particle diameter of 20 nm, and the balance as a solvent (a mixed solvent of ethyl acetate, normal propyl acetate, and isopropyl alcohol) were mixed in the proportions shown in the table and kneaded to prepare an ink composition for laser marking.

[0118] The ink composition after finishing contains 20% by mass of zinc oxide in the total amount. Also, the chlorine content in the total resin solid content in the ink composition is (Chlorine content contained in the total resin solid content in the ink composition) = (Chlorine contained in the total resin solid content in the ink composition) / (Mass of the total resin solid content in the ink composition) was determined by this method and was 0.3.

[0119] The viscosity of the obtained ink composition was diluted with a mixed solution of methyl ethyl ketone, ethyl acetate, and isopropyl alcohol (weight ratio 40:40:20), adjusted to 16 seconds (25 °C) with a Zahn cup #3 (manufactured by Rika Shakai), and printed solidly on a biaxially stretched polypropylene OPP film (P2161, thickness 20 μm, manufactured by Toyobo Co., Ltd.) using a gravure proofing machine equipped with a Helio 175 solid plate, and dried at 45 °C to obtain the printed matter of Example 1. The coating amount of the laser printing layer was 2.2 g / m 2 , and the film thickness was 1.0 μm.

[0120] Also, to the printed matter of Example 1, a dry laminate was performed using a urethane-based dry laminate adhesive Dick Dry LX-500 / KW-75 (manufactured by DIC) with a dry laminator (manufactured by DIC Engineering Co., Ltd.) to laminate an unstretched polypropylene film (hereinafter, CPP film: thickness 30 μm, manufactured by Toyobo Co., Ltd.), and aging was performed at 40 °C for 3 days to obtain a laminate.

[0121] (Examples 2, 3) In Example 1, the composition of the ink composition shown in the table and the coating amount and film thickness of the laser printing layer were used as Examples 2 and 3.

[0122] (Comparative Examples 1-9) In Example 1, the compositions of the ink compositions shown in the table and the coating amount and film thickness of the laser printing layer were used as Comparative Examples 1-9.

[0123] For titanium oxide, one with an average particle size of 0.27 μm was used. For precipitated barium sulfate, one with an average particle size of 0.3 μm was used.

[0124] Also, a salt vinyl resin solution adjusted as follows was used.

[0125] (Method for preparing the salt vinyl solution) A salt vinyl resin having a hydroxyl group (Solvaine A) manufactured by Nissin Chemical Industry Co., Ltd. was dissolved in methyl ethyl ketone so that the solid content was 15% by mass to obtain a salt vinyl resin solution. The chlorine content of the salt vinyl resin solution was 52.8%.

[0126] The following evaluations were performed on the printed matter or laminate of the examples and comparative examples.

[0127] 1) UV transmittance (%) Using a Shimadzu UV-3600 (integrating sphere type), the UV transmittance of the printed part of the laminate was measured. The measurement wavelength was 355 nm.

[0128] 2) Transparency (haze) Using a turbidity meter (NDH5000) manufactured by Nippon Denshoku Industries Co., Ltd., the transparency of the printed part of the printed matter was measured. The smaller the value, the higher the transparency.

[0129] 3) Adhesion After leaving the prepared printed matter for one day, a cellophane tape (12 mm wide, manufactured by Nichiban) was attached to the printed surface, and the appearance state of the printed film when this was rapidly peeled off was visually judged according to the following 5 grades.

[0130] 5: The printed film did not peel off at all. 4: 80% or more of the printed film remained on the film. 3: 50% or more and less than 80% of the printed film remained on the film. 2: More than 30% and less than 50% of the printed film remained on the film. 1: Less than 30% of the printed film remained on the film.

[0131] 4) Printability Regarding the prepared laminate, using an ultraviolet laser "FP-1000C" (manufactured by Keyence Corporation), printing with the ultraviolet laser was performed under the following conditions. All printing was performed from the side of the OPP film coated with the ink composition. 1) Laser power 50% 2) Scanning speed 2000 mm / second 3) Q-switch frequency 40 kHz 〇: Printing was possible. ×: Printing was not possible. Also, for those for which printing was possible, the color of the printing was confirmed.

[0132]

Table 1

[0133]

Table 2

[0134]

Table 3

Claims

1. An ink composition containing at least zinc oxide particles, a urethane resin, and a chlorinated polyolefin resin, wherein the chlorine content in the total resin solids of the ink composition is 1.5% by mass or less. An ink composition for ultraviolet laser marking.

2. Furthermore, containing a rosin resin The ink composition according to Claim 1.

3. The ink composition according to Claim 1 or 2, containing 50 to 90% by mass of a urethane resin and 5 to 10% by mass of a chlorinated polyolefin resin with respect to the total resin solids of the ink composition.

4. The ink composition according to Claim 1, wherein the ultraviolet region is 380 nm or less.

5. A printed matter obtained by printing the ink composition according to Claim 1 or 2 on a substrate.

6. The printed matter according to Claim 5, wherein the substrate is a polyolefin resin.

7. A laminate having the printed matter and another substrate.

8. A recycling method for reusing the printed matter according to Claim 6 or the laminate according to Claim 7 after melting.

9. A recycled material using the printed matter according to Claim 6 or the laminate according to Claim 7.

10. A recycled material using the printed matter according to Claim 6 or the laminate according to Claim 7.

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