JP5324789B2 - Active energy ray-curable resin composition for plastic film, plastic label, shrink label - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an active energy curable resin composition, which uses substantially no solvent, exhibits good curability in application to gravure printing and the like, forms a resin cured material layer having excellent adhesiveness to a plastic film, toughness, and followability to shrinking process after curing, and to provide a plastic label formed by applying the resin composition to a plastic film and provided with good surface scratch resistance, crumple resistance and the like. <P>SOLUTION: The active energy ray curable resin composition for a plastic film comprises an oxetane compound, an epoxy compound, and titanium oxide treated with alumina on the surface. A presence ratio of the aluminum element on the surface of the titanium oxide to all the elements is 1.0-2.5% by measurement based on the energy dispersive X-ray spectroscopy. <P>COPYRIGHT: (C)2009,JPO&amp;INPIT

Description

  The present invention relates to an active energy ray-curable resin composition used for a plastic film and a plastic label formed by applying the resin composition to a plastic film.

  Currently, plastic bottles such as PET bottles and metal bottles such as bottle cans are widely used as containers for beverages such as tea and soft drinks. In many cases, these containers are coated with a resin composition such as an ink or a coating agent for the purpose of displaying the contents and imparting various functions such as decorativeness, scratch resistance, and slipperiness. A label made of a plastic film (a so-called shrink label or stretch label) is attached.

  These resin compositions are required to have processability suitable for each label processing step, and the cured resin layer (hereinafter sometimes referred to as a resin cured product layer) is rubbed in the distribution process of the product for decoration. Toughness that does not deteriorate the performance and functionality is required. In recent years, in particular, in the beverage field, complicated and highly three-dimensionally molded containers are frequently used, and the required performance related to workability such as conformability to the container shape of a film to be mounted, particularly a shrink film, is Increasingly. In order to achieve both of these high workability and toughness, high adhesion of the cured resin layer to the film substrate is essential.

  By the way, when these resin compositions are applied to a substrate as a printing ink or the like, gravure printing is generally used. However, gravure ink usually contains a large amount of organic solvent. It is necessary to evaporate. In recent years, from the viewpoint of reducing the environmental burden, recovery and decomposition treatment of such a solvent has been made obligatory, and the capital investment and equipment maintenance cost for this have become a new burden on the gravure printing industry. On the other hand, in the case of water-based inks that do not use organic solvents or use a small amount of organic solvents, drying takes longer than solvent-based gravure inks, so printing speed is slow and productivity is unavoidable. It was.

  In light of these circumstances, development of coating agents based on epoxy resins that are substantially solvent-free is underway. Among them, epoxy compounds and oxetane are used as coating agents that impart flexibility to relatively brittle epoxy resins. A resin composition in which a compound is mixed is known (for example, see Patent Document 1).

International Publication No. 2007/007803 Pamphlet

  The present inventors proceeded with studies on the resin composition in which the epoxy compound and the oxetane compound are mixed, and by increasing the monofunctional oxetane content in the oxetane compound, the flexibility of the cured resin layer was improved, The present inventors have found that the followability to shrinkage processing in shrinkage shrink label applications and the like is further improved. However, in such a system in which the monofunctional oxetane content is increased, the curability by irradiation of active energy rays of the resin composition is lowered, and the curing rate is insufficient for use in high-speed gravure printing or flexographic printing. It turned out that the problem of becoming. In addition, in order to solve the above-mentioned curable problem, when light is sufficiently irradiated, there is a problem that the speed is lowered, so that it is not suitable for production, shrinks, or yellows.

  That is, the conventional resin composition has a problem that the formulation is limited to some extent in order to exhibit sufficient curability corresponding to high-speed printing even with low irradiation energy. Furthermore, this problem was particularly noticeable with white ink to which titanium oxide was added.

  The object of the present invention is a resin composition that does not substantially use a solvent, and is high in low irradiation energy even when, for example, an oxetane compound containing a large amount of monofunctional oxetane is used in various compounding formulations. For plastic films that can exhibit curable properties, and form a cured resin layer that has good adhesion to plastic films (also called adhesiveness) after curing, and has excellent toughness and followability to shrink processing, etc. The object is to provide an active energy ray-curable resin composition. It is another object of the present invention to provide a plastic label excellent in surface scratch resistance, resistance to fringing, and the like, which is obtained by coating the resin composition on a plastic film.

  As a result of intensive studies to achieve the above object, the present inventors have found that high curing can be achieved even in a system with a large amount of monofunctional oxetane by blending an oxetane compound, an epoxy compound, and titanium oxide subjected to a specific surface treatment. The present invention has been completed by finding that a resin composition capable of exhibiting properties and a plastic label having the above properties can be obtained.

That is, the present invention is a resin composition containing titanium oxide surface-treated with an oxetane compound, an epoxy compound, and alumina, and is measured on the surface of titanium oxide as measured by energy dispersive X-ray spectroscopy. The abundance ratio of the aluminum element to the element is 1.0 to 2.5%, and the compounding ratio [oxetane compound: epoxy compound] (weight ratio) of the oxetane compound and the epoxy compound is 5: 5 to 8: 2. An active energy ray-curable resin composition for a plastic film , wherein the oxetane compound is composed of 60 to 100% by weight of a monofunctional oxetane compound and 0 to 40% by weight of a bifunctional or higher oxetane compound. provide.

Furthermore, this invention provides the said active energy ray-curable resin composition for plastic films containing a photocationic polymerization initiator.
Furthermore, the present invention provides the active energy ray-curable resin composition for a plastic film, wherein the total amount of the oxetane compound and the epoxy compound is 45 to 65% by weight with respect to the total amount of the resin composition. To do.
Furthermore, the present invention provides the active energy ray-curable resin composition for plastic films, wherein the content of titanium oxide surface-treated with alumina is 25 to 50% by weight based on the total weight of the resin composition. Offer things.

  Furthermore, this invention provides the plastic label which has the resin cured material layer formed by apply | coating and hardening | curing the said active energy ray curable resin composition for plastic films to the at least single side | surface of a plastic film.

  Furthermore, this invention provides the shrink label which has the resin cured material layer formed by apply | coating and hardening | curing the said active energy ray curable resin composition for plastic films to the at least single side | surface of a shrink film.

  The active energy ray-curable resin composition for plastic films of the present invention has low viscosity, good coating properties on plastic films by gravure printing, flexographic printing, etc., and high curing speed, so that the production efficiency of plastic labels is high. improves. Moreover, since it is excellent in adhesiveness with a plastic film, it is excellent in scratch resistance and rub resistance. Moreover, since the mixing | blending which contains many monofunctional oxetanes is attained, the followable | trackability with respect to the deformation | transformation of the base film at the time of shrink processing is favorable. For this reason, the resin composition of the present invention is particularly useful as a printing ink or the like used by being applied to a plastic film. The plastic label formed by applying the resin composition is particularly useful as a label for use in plastic containers such as glass bottles and PET bottles, metal containers such as bottle cans, and the like.

  The active energy ray-curable resin composition for plastic film of the present invention (hereinafter sometimes simply referred to as “resin composition”) will be described in more detail below. The “resin composition” as used in the present invention refers to “a composition for forming a resin”.

  The resin composition of the present invention is an active energy ray-curable composition that can be cured by active energy rays such as visible light, ultraviolet rays, and electron beams. Unlike the case of thermosetting, it is also preferably used for a base material that easily deforms due to heat, such as a shrink film. Among the active energy rays, ultraviolet curable and near ultraviolet curable are particularly preferable. A preferable absorption wavelength is 200 to 460 nm.

  The resin composition of the present invention contains an oxetane compound, an epoxy compound, and titanium oxide surface-treated with alumina as essential components. When the three components are not included, the effect of the present invention cannot be obtained. Note that the oxetane compound and the epoxy compound do not include silicone having an oxetanyl group or an epoxy group.

  In addition to the above components, the resin composition of the present invention includes a cationic polymerizable active energy ray polymerization initiator (hereinafter sometimes referred to as a photocationic polymerization initiator) in order to develop active energy ray curability. It is preferable to contain. Moreover, it is preferable to contain a silicone compound (silicone oil etc.) from a viewpoint of sclerosis | hardenability improvement. Furthermore, for the purpose of imparting other functions, other resin components, sensitizers, dispersants, antioxidants, fragrances, deodorants, stabilizers, lubricants, color separation inhibitors, etc. are impaired. You may add to such an extent that it does not exist.

  The oxetane compound used in the resin composition of the present invention is a compound having at least one oxetanyl group in the molecule, and may be either a monomer or an oligomer. For example, oxetane compounds described in JP-A-8-85775 and JP-A-8-134405 can be used.

  Among the oxetane compounds, a compound having one oxetanyl group per molecule (monofunctional oxetane compound) is not particularly limited, but phenoxy-modified oxetane and ethylcyclohexane ring-containing oxetane are preferable. Specific examples of the monofunctional oxetane compound include 3-ethyl-3-[(phenoxy) methyl] oxetane, 3-ethyl-3- (hexyloxymethyl) oxetane, and 3-ethyl-3- (2- Ethylhexyloxymethyl) oxetane, 3-ethyl-3- (hydroxymethyl) oxetane, 3-ethyl-3- (chloromethyl) oxetane, and the like. Among these, 3-ethyl-3-[(phenoxy) methyl] oxetane is particularly preferable from the viewpoint of coating processability (printability) and the curability of the resin composition layer (coating layer).

  Examples of the compound having two or more oxetanyl groups in one molecule (bifunctional or more oxetane compound) include 1,4-bis [[(3-ethyloxetane-3-yl) methoxy] methyl] benzene, bis [1- Ethyl (3-oxetanyl)] methyl ether (above, bifunctional oxetane compound), oxetanylsilsesquioxane, oxetanyl silicate, phenol novolac oxetane (above, polyfunctional oxetane compound), and the like. Among these, from the viewpoints of curability and printability, the number of functional groups is preferably 2 or 3, particularly preferably 2. From the viewpoint of printability and the viewpoint of curability of the resin composition layer, bis [1-ethyl (3-oxetanyl)] methyl ether is particularly preferable.

  The oxetane compound can be produced according to a known method using oxetane alcohol and a halide (for example, xylene dichloride) produced from trimethylolpropane and dimethyl carbonate. In addition, you may use the existing oxetane compound, for example, "Aron oxetane OXT-101, 211, 212, 213" (above, monofunctional oxetane compound) by Toagosei Co., Ltd., "Aron by Toagosei Co., Ltd." Oxetane OXT-121, 221, 223 "(above, bifunctional oxetane compound)," Aron Oxetane OX-SQ-H, OX-SC, PNOX-1009 "(above, polyfunctional oxetane compound) manufactured by Toagosei Co., Ltd. Is commercially available.

  The oxetane compound is composed of 60 to 100% by weight of a monofunctional oxetane compound and 0 to 40% by weight of a bifunctional or higher oxetane compound (the total of the monofunctional oxetane compound and the bifunctional or higher oxetane compound is 100% by weight). It is preferable. More preferably, the monofunctional oxetane compound is 70 to 100% by weight (bifunctional or higher oxetane compound: 0 to 30% by weight), and still more preferably the monofunctional oxetane compound is 80 to 100% by weight (bifunctional or higher oxetane compound: 0). ˜20 wt%), most preferably the monofunctional oxetane compound is 90-100 wt% (bifunctional or higher oxetane compound: 0-10 wt%). As the blending ratio of the monofunctional oxetane compound in the oxetane compound increases, the followability to shrink processing improves. That is, when the amount of the monofunctional oxetane compound is less than the above blending range, the followability to shrinkage processing is reduced, and particularly when high shrinkage shrinkage processing (shrink processing) is performed, “ink cracking” Etc. may occur. On the other hand, when the ratio of the bifunctional or higher oxetane compound is increased, the curing rate is increased, and thus the productivity tends to be improved.

  As the epoxy compound used in the resin composition of the present invention, a known epoxy compound having at least one epoxy group in the molecule can be used, for example, an aliphatic epoxy compound, an alicyclic epoxy compound or an aromatic epoxy compound. Can be used. Among these, from the viewpoint of high reaction rate, a compound having a glycidyl group or a compound having an epoxycyclohexane ring is preferable, and an epoxy compound having two or more epoxy groups is preferable. For example, examples of the aliphatic epoxy compound include propylene glycol glycidyl ether. Examples of the alicyclic epoxy compound include 3,4-epoxycyclohexylmethyl-3 ', 4'-epoxycyclohexanecarboxylate and bis- (3,4-epoxycyclohexyl) adipate. Examples of the aromatic epoxy compound include bisphenol A glycidyl ether, glycidyl ether condensate of bisphenol A, and epichlorohydrin modified products of novolac resin and cresol resin.

  As the epoxy compound, one synthesized by a general method such as synthesis from epichlorohydrin and bisphenol A, or epoxidation of a cyclohexene compound with peracid can be used. For example, “Celoxide 2021” manufactured by Daicel Chemical Industries, Ltd. can be used. “Celoxide 2021P”, “Celoxide 2080”, “Epolide GT400”, “UVR6110” and “UVR6105” manufactured by Dow Chemical Co., Ltd. are commercially available.

  In the resin composition of the present invention, the mixing ratio of the oxetane compound and the epoxy compound [oxetane compound: epoxy compound] (weight ratio) is preferably 2: 8 to 8: 2, and when coating by gravure and flexographic printing, 5: 5 to 8: 2 are preferable, and 6: 4 to 7: 3 are more preferable. If the amount of the oxetane compound is larger than the above range, the initiation rate of the curing reaction of the resin composition is slowed down, and it takes time to cure, so that the productivity may be lowered or uncured in a normal curing process. is there. In addition, if the amount of the epoxy compound is larger than the above range, the viscosity of the resin composition becomes so large that it is difficult to uniformly apply by a coating method such as gravure printing or flexographic printing, or the curing reaction is stopped. This is likely to occur, resulting in a low molecular weight cured product, and the cured resin cured layer may be fragile.

  In the resin composition of the present invention, the total amount of the oxetane compound and the epoxy compound is preferably from 45 to 70% by weight, more preferably from the viewpoint of coatability, curability, and the like. 50 to 65% by weight.

The titanium oxide used in the resin composition of the present invention is titanium oxide (TiO ₂ ) whose surface is coated with alumina (Al ₂ O ₃ ). As the titanium oxide, any of rutile type (tetragonal high temperature type), anatase type (tetragonal low temperature type), brookite type (orthorhombic type) may be used, and known and conventional production such as sulfuric acid method, chlorine method, etc. What was manufactured by the method can be used. As the surface treatment method of alumina, a known and commonly used surface treatment (coating treatment) method can be used. For example, the surface treatment methods described in JP-A Nos. 2002-372797 and 2004-124077 are used. Can be used. In addition to the surface treatment with alumina, the titanium oxide may be further treated with another inorganic oxide such as silica, or may be treated with an organic compound such as a silane coupling agent or a titanium coupling agent. .

The abundance ratio of aluminum element to all elements on the surface of titanium oxide surface-treated with alumina (hereinafter sometimes referred to as “surface-treated titanium oxide”) is 1.0 to 2.5%, preferably Is 1.0 to 2.0%. The abundance ratio of the aluminum element is an amount corresponding to the surface coating amount (surface treatment amount) with alumina. Alumina surface treatment is thought to be due to the catalytic action of alumina in addition to the effect of preventing the aggregation of titanium oxide and improving the dispersibility in the resin composition, but promotes the cationic polymerization reaction (curing reaction). Presumed to be effective. If the abundance ratio of the aluminum element is less than 1.0%, the titanium oxides are likely to aggregate to cause poor dispersion, and further, the effect of improving the curability is insufficient and the productivity is lowered. On the other hand, when the abundance ratio of the aluminum element exceeds 2.5%, the curability decreases and the cured resin layer becomes brittle.

  The abundance ratio of the aluminum element is the total number of all elements detected within a fixed measurement field (100) when elemental analysis of the titanium oxide surface is performed by energy dispersive X-ray spectroscopy (EDX). %) Of the number of aluminum elements present (%).

  Although the average particle diameter of the said surface treatment titanium oxide is not specifically limited, 0.1-0.5 micrometer is preferable, More preferably, it is 0.2-0.4 micrometer. When the average particle size is less than 0.1 μm, the white density is lowered and the concealability is insufficient. If it exceeds 0.5 μm, so-called “plate fogging” (printing failure due to defective ink scraping of portions other than the image line portion of the plate) occurs during gravure printing.

  The content of the surface-treated titanium oxide is preferably 25 to 50% by weight, more preferably 30 to 45% by weight, based on the total weight of the resin composition, from the viewpoint of concealability and coarse protrusion formation suppression.

  Commercially available products may be used as the surface-treated titanium oxide. For example, trade names “JR-600A”, “JR-707”, “JR-405”, “JR-” manufactured by Teika Co., Ltd. may be used. 708 ”, a product name“ RDI-S ”manufactured by Kemira, and the like.

  The resin composition of the present invention preferably contains a silicone compound (silicone oil) from the viewpoint of improving the curing speed, adhesion to a substrate, slipperiness, and the like. The silicone compound in that case is not particularly limited, but is a polysiloxane having a main chain composed of a siloxane bond, and a straight silicone compound having no substituent other than a methyl group and a phenyl group (dimethylsilicone, methylphenylsilicone, methylhydrogen). Silicone), or a modified silicone compound having a substituent other than a methyl group or a phenyl group at the side chain or terminal.

  Examples of the substituent in the modified silicone include an epoxy group, a fluorine atom, an amino group, a carboxyl group, an aliphatic hydroxyl group (alcoholic hydroxyl group), an aromatic hydroxyl group (phenolic hydroxyl group), and a (meth) acryloyl group. Examples include a substituent and a substituent containing a polyether chain. Examples of the modified silicone having these substituents include epoxy-modified silicone, fluorine-modified silicone, amino-modified silicone, (meth) acryl-modified silicone, polyether-modified silicone, carboxyl-modified silicone, carbinol-modified silicone, phenol-modified silicone, Examples include diol-modified silicone. As these modified silicone compounds, for example, compounds described in International Publication No. 2007/007803 pamphlet can be used.

  The content of the silicone compound is preferably 0.5 to 10% by weight, more preferably 1 to 7% by weight, based on the total weight of the resin composition. If the content of the silicone compound is less than 0.5% by weight, the effect of improving slipperiness and curability cannot be obtained, and if it exceeds 10% by weight, the viscosity may be increased or the curability may be lowered.

  The resin composition of the present invention preferably contains an active energy ray polymerization initiator (hereinafter referred to as a photopolymerization initiator) in order to exhibit active energy ray curability. Although it does not specifically limit as a photoinitiator of this invention, A photocationic polymerization initiator is preferable. Although it does not specifically limit as a photocationic polymerization initiator, For example, a diazonium salt, a diaryl iodonium salt, a triaryl sulfonium salt, a silanol / aluminum complex, a sulfonic acid ester, an imide sulfonate etc. are mentioned. Of these, diaryl iodonium salts and triarylsulfonium salts are particularly preferable from the viewpoint of reactivity. Although content of a photocationic polymerization initiator is not specifically limited, 0.5-7 weight% is preferable with respect to the total weight of a resin composition, More preferably, it is 1-5 weight%.

Moreover, it is preferable that the resin composition of this invention contains a sensitizer as needed from a viewpoint of improving production efficiency. The sensitizer can be selected from existing sensitizers in consideration of the type of active energy ray used. For example, (1) amine sensitizers such as amines containing nitrogen in the ring, such as aliphatic, aromatic amines, piperidine, (2) urea sensitizers such as allyl, o-tolylthiourea, (3) sodium Sulfur compound sensitizers such as diethyldithiophosphate, (4) anthracene sensitizers, (5) nitrile sensitizers such as N, N-disubstituted-p-aminobenzonitrile compounds, (6) tri -Phosphorus compound sensitizers such as -n-butylphosphine, (7) Nitrogen compound sensitizers such as N-nitrosohydroxylamine derivatives and oxazolidine compounds, (8) Chlorine compound sensitizers such as carbon tetrachloride , (9) Sensitizers such as thioxanthone sensitizers may be mentioned. Also in the above, thioxanthone sensitizers and anthracene sensitizers are particularly preferred because of their strong sensitizing action. Of these, diethylthioxanthone, isopropylthioxanthone, 9,10-dibutoxyanthracene and the like are preferably used. Moreover, it is although it does not specifically limit as content of a sensitizer, 0.1 to 5 weight% is preferable with respect to the total weight of a resin composition, Most preferably, it is 0.3 to 3 weight%.

  Moreover, the resin composition of this invention may contain a lubricant as needed. Examples of the lubricant herein include various waxes such as polyolefin wax such as polyethylene wax, fatty acid amide, fatty acid ester, paraffin wax, polytetrafluoroethylene (PTFE) wax and carnauba wax.

  In the resin composition of the present invention, the content of the solvent mainly used as a dispersant without participating in the reaction is preferably 5% by weight or less, more preferably 1% by weight or less, Most preferably, it contains substantially no solvent. The solvent here refers to, for example, organic solvents such as toluene, xylene, methyl ethyl ketone, ethyl acetate, methyl alcohol, ethyl alcohol, and water. In gravure and flexographic printing inks, coating processability and coating agents are used. It is generally used for the purpose of improving the compatibility and dispersibility of each component therein, and does not include a reactive diluent incorporated into the cured resin composition. The resin composition of the present invention can exhibit excellent coating properties and dispersibility between components even without a solvent, and the amount of the solvent can be extremely reduced, eliminating the need for solvent removal, speeding up, and cost reduction. It is possible to reduce the environmental load.

  In general, oxetane compounds have a characteristic of forming a tough cured resin layer having a high molecular weight because the curing reaction is difficult to stop. On the other hand, the initiation reaction is also difficult to proceed, so that the curing process takes time and productivity is increased. There is a drawback that the resin composition is not cured or the toughness of the cured resin layer is insufficient when the curing time is short or short. On the other hand, the epoxy compound has a fast initiation reaction and a high production rate. However, since the reaction is likely to stop, the cured product has a low molecular weight and the toughness of the cured resin layer is insufficient. In the present invention, it is possible to obtain a certain degree of curing rate (productivity) and toughness by mixing both the oxetane compound and the epoxy compound. Furthermore, the curing rate can be improved by adding a silicone compound (particularly a modified silicone compound).

  However, with the above method alone, sufficient curability could not be obtained in all blended compositions of oxetane compound and epoxy compound. In particular, when used for high shrink type shrink label applications, the proportion of monofunctional oxetane compound in the oxetane compound is increased to further improve the followability to shrink processing (shrink processing). Although it is effective to improve the flexibility, if the ratio of the monofunctional oxetane compound increases in this way, the curability of the resin composition decreases, so that sufficient curability to withstand the demands of high-speed printing can be obtained. There was no case. Such a tendency was particularly remarkable in the white ink composition system in which titanium oxide was added as a white pigment.

  In the present invention, the titanium oxide to be added is subjected to a surface treatment with alumina, and the surface treatment amount is set to a specific range, so that it is difficult to obtain curability such as a system in which a large amount of the above monofunctional oxetane compound is blended. We have succeeded in exerting sufficient curability even in the system of the blend composition. Thereby, it became easy to change a compounding composition freely according to a use and the purpose, maintaining high sclerosis | hardenability. The details of the mechanism of action are not clear, but it is considered that the curing reaction (cationic polymerization reaction) is moderately accelerated by the catalytic action of alumina used for the surface treatment of titanium oxide.

  In the present invention, since the resin layer is hardened by irradiation with active energy rays for a short time, the process speed can be increased and the productivity is improved. Moreover, high molecular weight can be achieved in a short time and high toughness can be achieved. Furthermore, the adhesion of the resin composition to the plastic film substrate is dramatically improved. That is, productivity, adhesion, and toughness can be compatible at a high level. Moreover, high concealability is obtained by adding titanium oxide.

  Although the viscosity (23 ± 2 ° C.) of the resin composition of the present invention is not particularly limited, for example, when applied by gravure printing, 10 to 1000 mPa · s is preferable, and 20 to 500 mPa · s is more preferable. It is. When the viscosity exceeds 1000 mPa · s, the gravure printability is deteriorated, and “decrease” or the like is generated, and the decorating property may be deteriorated. On the other hand, when the viscosity is less than 10 mPa · s, the storage stability may be deteriorated, for example, the pigment or the additive may easily settle. The viscosity of the resin composition can be controlled by the blending ratio of each component, a thickener, a thickener, and the like. In the present specification, “viscosity” is JIS Z unless otherwise specified, using an E-type viscometer (conical plate-type rotational viscometer) under the conditions of 23 ± 2 ° C. and cylinder rotation speed of 50 rotations. The value measured according to 8803 is meant.

  The resin composition of the present invention is preferably applied by gravure printing, flexographic printing, or inkjet printing from the viewpoints of cost, productivity, printing decoration, and the like. Among these, a gravure printing method is particularly preferable.

  The resin composition of the present invention can be preferably used as a white printing ink. Since the cured resin layer by the resin composition of the present invention has excellent scratch resistance, the cured resin layer such as surface printing is provided on the outermost layer of the label (the outermost layer opposite to the adherend side such as the container). And may be used as a lower layer in the case of laminating a plurality of ink layers.

  The resin composition of the present invention is applied to a plastic film and used for a plastic label. Specifically, it can be used for stretch labels, shrink labels, stretch shrink labels, in-mold labels, tack labels, roll labels (wrap-type glued labels), heat-sensitive adhesive labels, and the like. Among these, from the viewpoint of adhesion of the resin composition of the present invention and followability during shrink processing, it is particularly preferably used as a shrink label by coating on a shrink film.

  By applying the resin composition of the present invention to at least one surface of a plastic film and curing with an active energy ray, a plastic label having the cured resin layer of the present invention can be obtained. The cured resin layer of the present invention may be provided on the outermost layer (for example, the outermost layer or the innermost layer) of the label, or may be provided as a lower layer of another ink layer. When the cured resin layer of the present invention is used as the outermost layer, an effect of imparting scratch resistance to the label can be obtained. In particular, when used for shrink label applications, the effect of preventing shrinkage peeling and shrinkage cracks (ink cracks) is obtained reflecting the good adhesion and followability to shrink processing. In addition, since the cured resin layer of the present invention has good adhesion to a plastic film, it exerts an excellent effect even when applied directly on the surface of the plastic film, but is not limited to this, the adhesive layer It may be provided through other layers.

  The type of plastic film used for the plastic label of the present invention can be appropriately selected according to the required physical properties, application, cost, etc., and is not particularly limited. For example, polyester, polyolefin, polystyrene, polyvinyl chloride Polyamide, aramid, polyimide, polyphenylene sulfide, acrylic resin and the like can be used. Among these, a polyester film, a polyolefin film, a polystyrene film, and a polyvinyl chloride film are preferable, and a polyester film and a polyolefin film are more preferable. As the polyester, polyethylene terephthalate (PET) or poly (ethylene-2,6-naphthalenedicarboxylate) (PEN) can be used, and as the polyolefin, polypropylene, polyethylene, cyclic olefin, or the like can be used. is there.

  The plastic film may be a single-layer film or a laminated film in which a plurality of film layers are laminated according to required physical properties, applications, and the like. In the case of a laminated film, film layers made of different resins may be laminated. For example, it may be a three-layer laminated film composed of a central layer and a surface layer portion (inner layer, outer layer), a film in which the central layer is composed of a polyolefin resin or a polystyrene resin, and a surface layer is composed of a polyester resin. Moreover, you may use any of an unstretched film, a uniaxially oriented film, and a biaxially oriented film according to a required physical property, a use, etc. In particular, when the plastic label is a shrink label, a uniaxial or biaxially oriented film is often used, and in particular, a film (substantially oriented) in the film width direction (direction that becomes the label circumferential direction). A film uniaxially stretched in the width direction is generally used.

  The plastic film can be produced by a conventional method such as melt film formation or solution film formation. It is also possible to use a commercially available plastic film. The surface of the plastic film may be subjected to conventional surface treatment such as corona discharge treatment or primer treatment, if necessary.

  The heat shrinkage rate (90 ° C., 10 seconds) of the plastic film is not particularly limited. For example, in the case of shrink label use, one direction in the width direction and the longitudinal direction is − 3 to 15% is preferable and the other direction is preferably 20 to 80%.

  Although the thickness of the said plastic film changes with uses and is not specifically limited, 10-200 micrometers is preferable, for example, in the case of a shrink label use, 20-80 micrometers is preferable, More preferably, it is 30-60 micrometers.

  The thickness of the resin layer when applying the resin composition of the present invention varies depending on the application and is not particularly limited, but is preferably 0.1 to 15 μm, more preferably 0.5 to 10 μm, particularly from the viewpoint of concealability. Preferably, it is 1-8 micrometers. It is. When the thickness of the resin layer is less than 0.1 μm, it may be difficult to provide the resin layer uniformly. When used as a printing layer, partial “fading” may occur. , Decorativeness may be impaired, or printing as designed may be difficult. In addition, when the resin layer thickness exceeds 15 μm, it becomes difficult to cure or consumes a large amount of the resin composition, which increases the cost and makes it difficult to apply uniformly. The material layer becomes fragile and can be easily peeled off. In addition, the thickness of the cured resin layer of the present invention hardly changes before and after curing.

  In addition, the plastic label of the present invention may be provided with a printed layer different from the cured resin layer of the present invention. In this case, the other printing layer can be formed by a conventional printing method such as gravure printing or flexographic printing. The printing ink used for forming the printing layer is composed of, for example, a pigment, a binder resin, and a solvent. Examples of the binder resin include acrylic, urethane, polyamide, vinyl chloride-vinyl acetate copolymer, cellulose, and nitro. Common resins such as cellulose can be used. The thickness of the printing layer is not particularly limited and is, for example, about 0.1 to 10 μm.

  In addition, the plastic label of the present invention may be provided with other layers such as an anchor coat layer, a primer coat layer, a nonwoven fabric, and paper, which are different from the cured resin layer of the present invention, as necessary.

  The plastic label of the present invention is generally mounted on a container and used as a labeled container. Such containers include, for example, soft drink bottles such as PET bottles, milk containers for home delivery, food containers such as seasonings, alcohol beverage bottles, pharmaceutical containers, containers for chemical products such as detergents and sprays, cups, etc. This includes noodle containers. Also, the material of the container includes plastic such as PET, glass, metal and the like. In addition, the plastic label of this invention may be used for adherends other than a container.

  Below, an example of the process which mounts the resin composition of this invention, the manufacturing method of a plastic label, and a plastic label to a container is demonstrated. In addition, although the example of the cylindrical shrink label using the shrink film shrink | contracted in the width direction as a plastic film is shown here, a manufacturing method and a processing method are not limited to this.

  In the following description, the original film before providing the cured resin layer is referred to as a “plastic film”, and the one provided with the cured resin layer of the present invention is referred to as a “(long) plastic label”. Furthermore, in the mounting process to the container, the long plastic label that has been processed into a cylindrical shape while being long is referred to as a “long cylindrical plastic label”.

[Preparation of resin composition]
The above-mentioned oxetane compound, epoxy compound, surface-treated titanium oxide, and, if necessary, a silicone compound, a photopolymerization initiator and the like are mixed to produce a resin composition. Furthermore, when using other additives, such as a sensitizer, it mixes simultaneously. For mixing, mixers such as butterfly mixers, planetary mixers, pony mixers, dissolvers, tank mixers, homomixers, homodispers, paint shakers, roll mills, sand mills, ball mills, bead mills, line mills, and kneaders are used. The obtained resin composition may be used after being filtered, if necessary.

[Production of plastic labels]
The resin composition of the present invention is applied to a plastic film (for example, gravure, flexographic printing, etc.) to form a resin layer (before curing). The coating may be provided by an in-line coat that is applied during the plastic film manufacturing process (for example, after unstretched or longitudinally uniaxially stretched), or may be provided by an off-line coat that is applied after film formation, Although not particularly limited, off-line coating is preferable from the viewpoint of productivity and workability including curing treatment.

Next, the resin layer is cured. Curing is preferably performed in a coating step and a series of steps from the viewpoint of productivity. Curing is performed by active energy ray curing using an ultraviolet (UV) lamp, an ultraviolet LED, an ultraviolet laser, or the like, and the active energy ray to be irradiated varies depending on the composition of the resin composition and is not particularly limited, but from the viewpoint of curability. In addition, ultraviolet rays (near ultraviolet rays) having a wavelength of 200 to 460 nm are preferable, and the integrated light amount is preferably 50 to 2000 (mJ / cm ² ).

  The long plastic label obtained as described above is slit into a predetermined width and wound into a roll to form a plurality of rolls.

[Processing of long plastic labels]
Next, while feeding out one of the rolls, the long plastic film is formed into a cylindrical shape so that the width direction is the circumferential direction. Specifically, a long plastic label is formed into a cylindrical shape, and a solvent or adhesive such as tetrahydrofuran (THF) or the like (hereinafter referred to as “THF”) is formed on one side edge of the label in a band shape in the longitudinal direction. Solvent etc.) is applied to the inner surface, rolled up into a cylindrical shape, and the solvent applied portion is overlapped at a position of 5-10 mm from the other side edge and adhered to the outer surface (center seal). To obtain a long cylindrical plastic label. In addition, it is preferable that the resin cured material layer is not provided in the part which apply | coats said solvent etc., and the part to adhere | attach.

  In the case where a perforation for label excision is provided, a perforation having a predetermined length and pitch is formed in the longitudinal direction. The perforation can be applied by a conventional method (for example, a method of pressing a disk-shaped blade having a cut portion and a non-cut portion repeatedly formed around it, a method using a laser, or the like). The process stage for perforating can be appropriately selected after the printing process and before and after the cylindrical processing process.

[Container with label]
Finally, after cutting the long cylindrical plastic label obtained above, it is attached to a predetermined container, and the label is contracted by heat treatment, and a container with a label is prepared by closely contacting the container. The above long cylindrical plastic label is supplied to an automatic label mounting device (shrink labeler), cut to the required length, and then externally fitted into a container filled with the contents, and a hot air tunnel or steam tunnel at a predetermined temperature is attached. Passed or heated with radiant heat such as infrared rays to cause heat shrinkage and adhere to the container to obtain a labeled container. Examples of the heat treatment include treatment with steam at 80 to 100 ° C. (passing through a heating tunnel filled with steam and steam).

[Methods for measuring physical properties and methods for evaluating effects]
(1) Presence ratio of aluminum element to all elements on titanium oxide surface Using energy dispersive X-ray spectroscopy (EDX) using an energy dispersive X-ray analyzer “EMAX ENERGY-210” manufactured by HORIBA, Ltd. Elemental analysis was performed under the following conditions.
Calculate the ratio of the number of aluminum elements present (%) when the total number of elements detected in the field of analysis obtained from elemental analysis is 100%, and aluminum elements relative to all elements on the titanium oxide surface The abundance ratio.
(sample)
Titanium oxide (powder) was placed on a sample stage and measured by gold vapor deposition (20 seconds).
(Measurement condition)
Measurement field of view (analysis field of view): Measurement was performed at a magnification of 100 times and in a field of view where titanium oxide particles could be clearly confirmed.
(Equipment conditions)
High vacuum Signal: Secondary electron Acceleration voltage: 10 keV

(2) Curability (Surface tackiness)
In Examples and Comparative Examples, curing treatment is performed at an ultraviolet irradiation process speed of 70, 100, and 120 m / min. Immediately after the treatment, the surface of the cured resin layer is touched with a finger, and whether or not the finger is inked is visually observed. Judgment was made based on the following criteria.
Ink does not stick at 120m / min. : Excellent curability (◎)
Ink is not applied at 100 m / min, but ink is applied at 120 m / min. : Good curability (○)
Ink is not applied at 70 m / min, but ink is applied at 100 m / min. : Usable level (△)
Ink is applied even at 70 m / min. : Hardening failure (×)

(3) Adhesion (tape peeling test)
The test was conducted in accordance with JIS K 5600, except that the cross cut of the grid was not made. The Nichiban tape (width 18 mm) was applied to the surface of the cured resin layer side of the plastic label obtained in the examples and comparative examples, peeled in the direction of 90 degrees, and in the region of 5 mm × 5 mm, the cured resin layer The remaining area was observed, and the adhesion (adhesiveness) of the base material to the plastic film (PET film) was judged according to the following criteria.
90% or more: Good adhesion (○)
80% or more and less than 90%: Adhesiveness is slightly poor but usable level (△)
Less than 80%: poor adhesion (×)

(4) Shrink process suitability The shrinkage label obtained by Examples 1 and 6 to 9 (cured at an ultraviolet irradiation rate of 70 m / min, resin cured product layer thickness: 2 μm) is placed in a PET bottle with a maximum shrinkage portion. The length in the circumferential direction was adjusted so as to be heat-shrinked by 20%, formed into a cylindrical shape, and welded at both ends to obtain a cylindrical plastic label.
The cylindrical plastic label was attached to a 500 ml PET bottle, and the label was shrunk in a steam tunnel having an atmospheric temperature of 90 ° C. to obtain a labeled container.
The state of the label was visually observed, and the suitability for shrink processing was judged according to the following criteria.
Adhering perfectly to the container shape without any problem in appearance: Good shrink processing suitability (○)
As for the label as a whole, the ink (cured resin layer) follows the shrinkage, but does not follow completely at the high shrinkage part and looks like printing unevenness: Usable level (△)
Ink (resin cured product layer) does not follow the shrinkage as a whole label, and folding, wrinkles, etc. are seen at the edge: Defective shrink processing (×)

(5) Thermal shrinkage (90 ° C., 10 seconds)
A rectangular sample piece having a length of 200 mm (mark interval 150 mm) and a width of 10 mm is formed from a plastic film or a plastic label in the measurement direction (longitudinal direction or width direction).
The sample piece is heat-treated in warm water at 90 ° C. for 10 seconds (under no load), the difference between the marked lines before and after the heat treatment is read, and the thermal contraction rate is calculated by the following formula.
Thermal shrinkage (%) = (L ₀ −L ₁ ) / L ₀ × 100
L ₀ : Mark interval before heat treatment L ₁ : Mark interval after heat treatment

  EXAMPLES Hereinafter, the present invention will be described in more detail based on examples, but the present invention is not limited to these examples.

Example 1
Monofunctional oxetane compound (manufactured by Toagosei Co., Ltd., trade name “Aron Oxetane OXT-211”), epoxy compound (manufactured by Daicel Chemical Industries, Ltd., trade name “Celoxide 2021P”), titanium dioxide subjected to alumina surface treatment (Trade name “JR-600A” manufactured by Teika Co., Ltd.), silicone compound (trade name “TEGO rad 2500” manufactured by Degussa), photopolymerization initiator (trade name “UVI-6992” manufactured by Dow Chemical Co., Ltd.) ), A sensitizer (manufactured by Kawasaki Kasei Kogyo Co., Ltd., trade name “Anthracure UVS-1331”) and wax (manufactured by Sazol Co., Ltd., trade name “SPRAY 105”) are shown in Table 1 The active energy ray-curable resin composition (white ink) was obtained. No solvent was used. The obtained resin composition was free from gelation and yellowing and had good properties as a printing ink.
Polyethylene terephthalate (PET) type shrink using the obtained resin composition using a table gravure printing machine (manufactured by Nissho Gravure Co., Ltd., trade name “GRAVO PROOF MINI”) and a gravure plate with 90 lines and a plate depth of 35 μm. On one side of the film (trade name “S7042”: film thickness 45 μm, manufactured by Toyobo Co., Ltd.), full-surface gravure printing (resin layer thickness: 2 μm) was performed at a process speed of 70 m / min.
Subsequently, on the shrink film coated with the above resin composition, using an ultraviolet irradiation device (Fusion UV Systems Japan Co., Ltd., trade name “LIGHT HAMMER 10”: output 100%, D bulb), 240 W / Light irradiation was performed under conditions of cm, and the curability was evaluated by changing the ultraviolet irradiation process speed (conveyor speed). The irradiation intensity (measured by the trade name “UV Power Pack” manufactured by EIT Co., Ltd.) is 55 mJ / cm ² (UVC), 515 mJ / cm ² (UVB), 1550 mJ when the conveyor speed is 10 m / min. / Cm ² (UVA) and 955 mJ / cm ² (UVV).
Further, a plastic label (shrink label) was produced at an ultraviolet irradiation rate of 70 m / min, and adhesion was evaluated for the obtained plastic label (resin cured product layer thickness: 2 μm).
As shown in Table 1, the obtained resin composition had good curability, and the obtained plastic label had excellent adhesion.

Examples 2-5
As shown in Table 1, the resin composition and the plastic label were obtained in the same manner as in Example 1 by changing the type of titanium oxide (the abundance ratio of the aluminum element on the surface).
As shown in Table 1, the obtained resin composition had good properties as an ink and was excellent in curability. Moreover, the obtained plastic label had excellent adhesiveness.

Comparative Examples 1-3
As shown in Table 1, the resin composition and the plastic label were obtained in the same manner as in Example 1 by changing the type of titanium oxide (the abundance ratio of the aluminum element on the surface).
The obtained resin composition had poor curability, and the obtained plastic label had inferior adhesion to the cured resin layer.

Examples 6-9
As shown in Table 2, as the oxetane compound, a monofunctional oxetane compound (manufactured by Toagosei Co., Ltd., trade name “Aron oxetane OXT-211”) and a bifunctional oxetane compound (manufactured by Toagosei Co., Ltd., trade name “Aron oxetane”). Using OXT-221 "), a resin composition and a plastic label were obtained in the same manner as in Example 1. The obtained resin composition had good properties as an ink and was excellent in curability as shown in Table 2. Moreover, the obtained plastic label had excellent adhesiveness.

About the plastic label obtained in Example 1, 6-9, according to the said evaluation method (4), shrink process suitability was evaluated further.
As a result, the plastic labels of Examples 1, 6, and 7 showed excellent shrinkability, and the plastic label of Example 8 had shrinkability that could be used practically as a shrink label. On the other hand, the plastic label of Example 9 was inadequate for shrink processing as a shrink label.

The components and additives used in Tables 1 and 2 are as follows. The unit of the blending amount in the table is “parts by weight”.
[Oxetane compounds]
Monofunctional oxetane compound: manufactured by Toagosei Co., Ltd., trade name “Aron Oxetane OXT-211” (3-ethyl-3-phenoxymethyloxetane (POX))
Bifunctional oxetane compound: manufactured by Toagosei Co., Ltd., trade name “Aron oxetane OXT-221” (bis [1-ethyl (3-oxetanyl)] methyl ether (DOX))
[Epoxy compound]
Epoxy compound: manufactured by Daicel Chemical Industries, Ltd., trade name “Celoxide 2021P” (3,4-epoxycyclohexylmethyl-3 ′, 4′-epoxycyclohexanecarboxylate)
[Titanium oxide (titanium dioxide)]
Titanium oxide 1: manufactured by Teika Co., Ltd., trade name “JR-600A”
Titanium oxide 2: manufactured by Teika Co., Ltd., trade name “JR-707”
Titanium oxide 3: manufactured by Teika Co., Ltd., trade name “JR-405”
Titanium oxide 4: manufactured by Teika Co., Ltd., trade name “JR-708”
Titanium oxide 5: Product name “RDI-S” manufactured by Kemira
Titanium oxide 6: manufactured by Teika Co., Ltd., trade name “JR-808”
Titanium oxide 7: manufactured by Teika Co., Ltd., trade name “JR-809”
Titanium oxide 8: Product name “JR-600E” manufactured by Teika Co., Ltd.
[Other additives]
Silicone compound: manufactured by Degussa, trade name “TEGO rad 2500” (acrylic modified silicone)
Photopolymerization initiator: Product name “UVI-6992” manufactured by Dow Chemical
Sensitizer: Product name “Anthracure UVS-1331” (9,10-dibutoxyanthracene), manufactured by Kawasaki Kasei Kogyo Co., Ltd.
Wax: Product name “SPRAY 105” (olefin wax), manufactured by Sazol Co., Ltd.

Claims (6)

Presence of aluminum element with respect to all elements on the surface of titanium oxide measured by energy dispersive X-ray spectroscopy, which is a resin composition containing titanium oxide surface-treated with oxetane compound, epoxy compound, and alumina The ratio is 1.0-2.5% ,
The blending ratio [oxetane compound: epoxy compound] (weight ratio) of the oxetane compound and the epoxy compound is 5: 5 to 8: 2.
2. The active energy ray-curable resin composition for plastic film , wherein the oxetane compound is composed of 60 to 100% by weight of a monofunctional oxetane compound and 0 to 40% by weight of a bifunctional or higher oxetane compound . Furthermore, the active energy ray curable resin composition for plastic films of Claim 1 containing a photocationic polymerization initiator. The active energy ray-curable resin composition for a plastic film according to claim 1 or 2, wherein the total amount of the oxetane compound and the epoxy compound is 45 to 65% by weight based on the total amount of the resin composition. The active energy for a plastic film according to any one of claims 1 to 3, wherein the content of the titanium oxide surface-treated with alumina is 25 to 50% by weight based on the total weight of the resin composition. A linear curable resin composition. The plastic label which has the resin cured material layer formed by apply | coating and hardening the active energy ray curable resin composition for plastic films of any one of Claims 1-4 to the at least single side | surface of a plastic film. The shrink label which has a resin hardened | cured material layer formed by apply | coating and hardening the active energy ray curable resin composition for plastic films of any one of Claims 1-4 to the at least single side | surface of a shrink film.