Title of invention: Ink composition for laser marking and packaging material
Technical field
[0001]
　The present invention relates to an ink composition for laser marking and a packaging material.
Background technology
[0002]
　For various packaging containers that contain foods, beverages, pharmaceuticals, non-pharmaceutical products, cosmetics, etc., and packaging materials such as various packaging materials such as films and paper, the product name, lot number, date of manufacture, etc. Various information such as the expiration date, the expiration date, and the manufacturer's name are recorded. As a method for performing such recording, a laser marking method for recording (so-called laser printing) by irradiating an object with laser light has become widespread.
[0003]
　Since the laser marking method is a so-called non-contact type, it has advantages such as high-precision recording, high-speed recording, and recording on various surface shapes of an object. is there. Further, the laser marking method has an advantage that it enables recording that is hard to erase as compared with the recording by the hot stamp method or the inkjet method.
[0004]
　In the laser marking method, marking is performed by forming a laser marking layer with ink on an object to be laser marked and irradiating the laser marking layer with laser light. In such a laser marking method, various studies have been made to date to enable highly visible laser printing.
[0005]
　For example, in Patent Document 1, in order to enable clear laser printing, a colored ink layer to be laser-printed and a silver ink layer (reflection layer) for reflecting laser light on the colored ink layer are provided on a base material. Packaging materials have been proposed. Further, for example, in Patent Document 2, an ammonium octamolybdate is used to enhance visibility, and an ink composition for laser marking containing the same, a predetermined polyurethane resin, a vinyl chloride vinyl acetate copolymer resin, and an organic solvent. Has been proposed.
Prior art literature
Patent documents
[0006]
Patent Document 1: Japanese Patent Application Laid-Open No. 2011-148197
Patent Document 2: Japanese Patent Application Laid-Open No. 2016-222822
Outline of the invention
Problems to be solved by the invention
[0007]
　Laser printing with high visibility can be performed in the laser marking layer without resorting to means such as providing a layer other than the laser marking layer, such as the reflective layer disclosed in Patent Document 1, described above. It is beneficial to make it possible. For that purpose, it is considered necessary to use a special color-developing pigment in the ink composition forming the laser marking layer, such as the ammonium octamolybdate disclosed in Patent Document 2 described above.
[0008]
　However, in the laser marking method, it is desired to form a laser marking layer that enables recording with good visibility by using an inexpensive ink composition without using a special coloring pigment.
[0009]
　Therefore, the present invention provides an ink composition for laser marking capable of forming a laser marking layer capable of recording with good visibility without using a special coloring pigment such as ammonium octamolybdate. It is something to try.
Means to solve problems
[0010]
　The present invention is an ink composition used for forming a laser marking layer, which contains a binder resin (A) and titanium oxide (B) that causes color development in the laser marking layer by irradiation with laser light. The titanium oxide (B) includes titanium oxide (b 1 ) surface-treated with alumina, titanium oxide (b 2 ) surface-treated with alumina and silica, and titanium oxide (b ) coated with antimony-doped tin oxide. A laser marking ink composition containing at least one surface-treated titanium oxide ( BI ) selected from the group consisting of 3 ) and satisfying at least one of the following conditions 1 and 2 is provided.
　Condition 1: with respect to the content of the binder resin (A), the said surface-treated titanium oxide (B I ratio of the content of) (B I / A) is, on a solids weight ratio, in 2.5 to 6.5 is there.
　Condition 2: The titanium oxide (B) contains at least the titanium oxide (b 3 ), and the ratio of the content of the titanium oxide (b 3 ) to the content of the binder resin (A) (b 3 / A). ) Is 1.0 to 6.5 in terms of solid content mass ratio.
[0011]
　Further, the present invention is an ink composition used for forming a laser marking layer, and contains a binder resin (A) and titanium oxide (B) that causes color development in the laser marking layer by irradiation with laser light. and the titanium oxide (B) is antimony-doped tin oxide which was coating-treated titanium oxide (b 3 and), the titanium oxide (b 3 ) than titanium oxide oil absorption amount is 19 g / 100 g or more (b 4 The ratio of the total content of the titanium oxide (b 3 ) and the titanium oxide (b 4 ) to the content of the binder resin (A) [(b 3 + b 4 ) / A]. Provided is an ink composition for laser marking having a solid content mass ratio of 1.0 to 6.5.
Effect of the invention
[0012]
　According to the present invention, there is provided an ink composition for laser marking capable of forming a laser marking layer capable of recording with good visibility without using a special coloring pigment such as ammonium octamolybdate. can do.
Mode for carrying out the invention
[0013]
　Hereinafter, embodiments of the present invention will be described, but the present invention is not limited to the following embodiments.
[0014]

　The laser marking ink composition of the embodiment of the present invention (hereinafter, may be simply referred to as "ink composition") is used for forming a laser marking layer. is there. This ink composition contains a binder resin (A) and titanium oxide (B) that causes color development in the laser marking layer by irradiation with laser light.
[0015]
　The present inventors have made extensive studies on an ink composition capable of forming a laser marking layer that enables recording with good visibility without using a special coloring pigment such as ammonium octamolybdate. As a result, by using an ink composition in which titanium oxide subjected to a specific surface treatment is contained in a binder resin in a specific amount, the laser color development property is specifically enhanced and the recording with good visibility is performed. It has been found that a laser marking layer that enables the above can be obtained.
[0016]
　That is, the ink composition of the first aspect contains titanium oxide (B) as titanium oxide (b 1 ) surface-treated with alumina, titanium oxide (b 2 ) surface-treated with alumina and silica, and antimony-doped. coating treated titanium oxide with tin oxide (b 3 at least one surface-treated titanium oxide selected from the group consisting of) (B I containing). Then, this ink composition satisfies at least one of the following conditions 1 and 2.
　Condition 1: with respect to the content of the binder resin (A), the surface-treated titanium oxide (B I ratio of the content of) (B I / A) is in solid mass ratio, from 2.5 to 6.5.
　Condition 2: Titanium oxide (B) contains at least titanium oxide (b 3 ), and the ratio of the content of titanium oxide (b 3 ) to the content of the binder resin (A) (b 3 / A) is solid. The fractional mass ratio is 1.0 to 6.5.
[0017]
　Further, as a result of diligent studies, the present inventors have made an ink composition in which a combination of titanium oxide subjected to a specific surface treatment and titanium oxide having a specific oil absorption amount is contained in a binder resin in a specific amount. It was found that by using the above, the laser color development property is specifically enhanced, and a laser marking layer capable of recording with good visibility can be obtained.
[0018]
　That is, in the ink composition of the second aspect, as titanium oxide (B), titanium oxide (b 3 ) coated with antimony-doped tin oxide and oil absorption other than the titanium oxide (b 3 ) are 19 g / g /. It contains 100 g or more of titanium oxide (b 4 ). Then, in this ink composition, the ratio of the total content of titanium oxide (b 3 ) and titanium oxide (b 4 ) to the content of the binder resin (A) [(b 3 + b 4 ) / A] is determined. The solid content mass ratio is 1.0 to 6.5.
[0019]
　By printing the ink composition of one embodiment of the present invention on a substrate to be provided with a laser marking layer, a laser marking layer containing a binder resin and a specific titanium oxide in a specific ratio is used as a base. Can be formed on wood. By irradiating the laser marking layer with a laser beam, it is possible to perform recording with good visibility (laser marking). Further, the above ink composition can be prepared at a low cost because it is possible to form a laser marking layer that enables recording with good visibility without containing a special coloring pigment such as ammonium octamolybdate. obtain. Next, each component of the ink composition will be described.
[0020]
　The binder resin (A) is not particularly limited as long as it is a resin that can be used as an ink composition. Suitable binder resin (A) includes, for example, acrylic resin, urethane-modified acrylic resin, styrene-acrylic copolymer resin, ethylene-acrylic copolymer resin, polyurethane resin, polyester resin, polystyrene resin, and rosin-modified malein. Examples thereof include acid resins, vinyl chloride-vinyl acetate copolymer resins, ethylene-vinyl acetate copolymer resins, polyvinyl acetal resins, and polyamide resins, and cellulose-based resins such as hydroxyethyl cellulose, hydroxypropyl cellulose, and nitrocellulose. .. One of these can be used alone or in combination of two or more. In the present specification, the acrylic resin is 50 mol% or more (preferably) of the structural units derived from the monomer having an acryloyl group and / or the methacryloyl group with respect to all the structural units derived from the monomers constituting the acrylic resin. A resin containing 60 mol% or more).
[0021]
　The binder resin to be used can be appropriately selected depending on the material of the base material to which the ink composition (laser marking layer) is provided, the application in which the base material is used, and the like. For example, when an amorphous PET (A-PET) film used for a food packaging container (food tray, etc.) is used as a base material, the binder resin (A) in the ink composition provided on the base material may be used. It is preferable to use one or more of polyurethane resin, acrylic resin, and cellulose resin. Among them, it is more preferable to use either one or both of the acrylic resin and the cellulosic resin, and it is further preferable to use the acrylic resin and the cellulosic resin together.
[0022]
　When a plastic film such as a PET film used for a laminated packaging material is used as a base material, a polyurethane resin is used as the binder resin (A) in the ink composition provided on the base material from the viewpoint of laminating suitability. It is preferable to use it. Since the binder resin (A) contains the polyurethane resin, the laser marking layer formed by the ink composition can be suitably used for the laminated packaging material. Further, when a PET shrink film used for a shrink packaging label used for, for example, a PET bottle is used as a base material, the binder resin (A) in the ink composition provided on the base material is a polyurethane resin or cellulose. It is preferable to use either one or both of the based resins, and it is more preferable to use the polyurethane resin and the cellulose based resin together.
[0023]
　The above-mentioned polyurethane resin is obtained, for example, by synthesizing a urethane prepolymer by reacting a diisocyanate compound with a polyol compound, and reacting the urethane prepolymer with a chain extender and a reaction terminator as necessary. As the diisocyanate compound, the polyol compound, the chain extender, and the reaction terminator, known ones that have been conventionally used can be used.
[0024]
　Examples of the diisocyanate compound include aromatic diisocyanates, aliphatic diisocyanates, and alicyclic diisocyanates. Specific examples of aromatic diisocyanis include 2,4-tolylene diisocyanis, 2,6-tolylene diisocyanate, xylene-1,4-diisocyanis, xylene-1,3-diisocyanate, 4,4-diphenylmethane diisocyanate, 2, 4-diphenylmethane diisocyanate, 4,4-diphenyl ether diisocyanate, 2-nitrodiphenyl-4,4-diisocyanate, 2,2-diphenylpropane-4,4-diisocyanate, 3,3-dimethyldiphenylmethane-4,4-diisocyanate, 4 , 4-Diphenylpropane diisocyanate, m-phenylenediisocyanis, p-phenylenediisocyanate, naphthylene-1,4-diisocyanate, naphthylene-1,5-diisocyanate, and 3,3-dimethoxydiphenyl-4,4-diisocyanate. Can be done. Specific examples of the aliphatic diisocyanate include tetramethylene diisocyanate, hexamethylene diisocyanate, and lysine diisocyanate. Specific examples of the alicyclic diisocyanate include isophorone diisocyanate, norbornane diisocyanate, hydrogenated tolylene diisocyanate, hydrogenated xylene diisocyanate, and hydrogenated diphenylmethane diisocyanate. These diisocyanate compounds may be used alone or in combination of two or more.
[0025]
　ポリオール化合物としては、例えば、ポリエステルポリオール、ポリカーボネートポリオール、及びポリエーテルポリオール等を挙げることができる。ポリオール化合物は、１種単独で又は２種以上を組み合わせて用いることができる。ポリエステルポリオールとしては、例えば、多価カルボン酸類と、多価アルコール類又は第２～３級アミン類との脱水重縮合反応で得られる、ポリエステルポリオール又はポリエステルアミドポリオールが挙げられる。多価カルボン酸類の具体例としては、コハク酸、アジピン酸、セバシン酸、アゼライン酸、テレフタル酸、イソフタル酸、オルソフタル酸、ヘキサヒドロテレフタル酸、ヘキサヒドロイソフタル酸、ヘキサヒドロオルソフタル酸、及びナフタレンジカルボン酸；並びにトリメリット酸等のポリカルボン酸；並びにそれらの酸エステル；並びにそれらの酸無水物等が挙げられ、これらのうちの１種以上を用いることができる。多価アルコール類の具体例としては、エチレングリコール、１，２－プロパンジオール、１，３－プロパンジオール、１，２－ブタンジオール、１，３－ブタンジオール、１，４－ブタンジオール、１，５－ペンタンジオール、１，６－ヘキサンジオール、３－メチル－１，５－ペンタンジオール、ネオペンチルグリコール、１，８－オクタンジオール、１，９－ノナンジオール、ジエチレングリコール、ジプロピレングリコール、１，４－シクロヘキサンジメタノール、ビスフェノールＡのエチレンオキシド又はプロピレンオキシド付加物、トリメチロールプロパン、グリセリン、及びペンタエリスリトール等の低分子アルコール化合物；並びにモノエタノールアミン及びジエタノールアミン等の低分子アミノアルコール化合物；等が挙げられ、これらのうちの１種以上を用いることができる。第２～３級アミン類の具体例としては、ヘキサメチレンジアミン、キシリレンジアミン、及びイソホロンジアミン等の低分子アミン化合物等が挙げられ、これらのうちの１種以上を用いることができる。また、ポリエステルポリオールとしては、例えば、低分子アルコール化合物及び低分子アミノアルコール化合物等を開始剤として、ε－カプロラクトン及びγ－バレロラクトン等の環状エステル（ラクトン）モノマーを開環重合して得られるラクトン系ポリエステルポリオールを用いることもできる。
[0026]
　Examples of the polycarbonate polyol include those obtained by dehydrochloric acid reaction between a low molecular weight alcohol compound used for synthesizing a polyester polyol and phosgene, the low molecular weight alcohol compound, diethylene carbonate, dimethyl carbonate, diethyl carbonate, diphenyl carbonate and the like. Examples thereof are those obtained by the transesterification reaction with.
[0027]
　Examples of the polyether polyol include low molecular weight alcohol compounds, low molecular weight amine compounds, and low molecular weight amino alcohol compounds used for the synthesis of polyester polyols, and ethylene oxide, propylene oxide, butylene oxide, etc., using phenols and the like as initiators. Examples thereof include alkylene oxide, polyoxyethylene polyol obtained by ring-opening polymerization of tetrahydrofuran and the like, polyoxypropylene polyol, polytetramethylene ether polyol, polyoxyethylene polyoxypropylene polyol and the like. Further, the above-mentioned polyester polyol and polyester ether polyol using a polycarbonate polyol as an initiator can be mentioned.
[0028]
　Examples of the chain extender include aliphatic diamines such as ethylenediamine, propylenediamine, tetramethylenediamine, and hexamethylenediamine; alicyclic diamines such as isophoronediamine and 4,4′-dicyclohexylmethanediamine; and toluylene diamines. Aromatic diamines; Aromatic aliphatic diamines such as xylenediamine; N- (2-hydroxyethyl) ethylenediamine, N- (2-hydroxyethyl) propylenediamine, and N, N'-di (2-hydroxyethyl) ethylenediamine Diamines having hydroxyl groups such as; and diol compounds such as ethylene glycol, propylene glycol, 1,4-butanediol, neopentyl glycol, diethylene glycol, and triethylene glycol; and the like can be mentioned. Further, polyamines such as diethylenetriamine and triethylenetetramine can be used in combination as long as the polyurethane resin does not gel.
[0029]
　Reaction terminators include monoalkylamines such as n-propylamine and n-butylamine; dialkylamines such as di-n-butylamine; alkanolamines such as monoethanolamine and diethanolamine; and monoalcohols such as ethanol. Etc. can be exemplified.
[0030]
　The weight average molecular weight (Mw) of the polyurethane resin is preferably 5,000 to 100,000, more preferably 10,000 to 60,000. When the Mw of the polyurethane resin is 5,000 or more, it is easy to increase the film cohesive force of the laser marking layer, and it is easy to obtain adhesion to the base material and laminating resistance. On the other hand, when the Mw of the polyurethane resin is 100,000 or less, it is easily dissolved in a solvent, the fluidity of the ink (ink composition) becomes good, and good printing becomes possible. From this viewpoint, the Mw of the polyurethane resin is more preferably 80,000 or less, still more preferably 60,000 or less. If the molecular weight, chemical structure, and equivalent ratio of each component are different, the hardness of the obtained polyurethane resin will also be different. Therefore, by appropriately combining these components, the adhesion and blocking resistance of the laser marking layer to the substrate can be improved. It is possible to adjust. In the present specification, the weight average molecular weight of the polyurethane resin is a polystyrene-equivalent value measured by gel permeation chromatography (GPC).
[0031]
　When the laminating suitability when applying the ink composition to the base material used for the above-mentioned laminated packaging material is more required, the binder resin (A) is a vinyl chloride vinyl acetate copolymer resin together with the above-mentioned polyurethane resin. It may be included. Further, from the viewpoint of adhesion when the ink composition is applied to the PET shrink film used for the shrink packaging label described above, the binder resin (A) is copolymerized with vinyl chloride acetate with the polyurethane resin described above. It may contain a resin. In these cases, as the binder resin (A), a mixture of a polyurethane resin and a vinyl chloride vinyl acetate copolymer resin may be used. The vinyl chloride vinyl acetate copolymer resin is obtained by copolymerizing a monomer component containing vinyl chloride and vinyl acetate.
[0032]
　The content of the binder resin (A) is 5 based on the total mass of the solid content of the ink composition from the viewpoints of the cohesive force of the laser marking layer, the adhesion to the substrate, and the color development property by irradiation with laser light. It is preferably ~ 50% by mass. From the viewpoint of obtaining a laser marking layer having an appropriate cohesive force and adhesion, the content of the binder resin (A) in the total solid content of the ink composition is preferably 5% by mass or more, preferably 10% by mass. It is more preferably 12% by mass or more, and further preferably 12% by mass or more. On the other hand, from the viewpoint of obtaining a laser marking layer showing good color development by irradiation with laser light, the content of the binder resin (A) in the total solid content of the ink composition is preferably 50% by mass or less. , 30% by mass or less, and even more preferably 25% by mass or less.
[0033]
　Titanium oxide (B) is essential for developing the color of the laser marking layer by laser light. In the ink composition of the first aspect, the titanium oxide (B) is titanium oxide (b 1 ) surface-treated with alumina, titanium oxide (b 2 ) surface-treated with alumina and silica, and antimony-doped tin oxide. in coating treated titanium oxide (b 3 including at least one selected from the group consisting of). Hereinafter, titanium oxide (b 1 ) is treated with alumina (b 1 ), titanium oxide (b 2 ) is treated with an alumina-silica composite treated titanium oxide (b 2 ), and titanium oxide (b 3 ) is treated with ATO treated titanium oxide (b 3 ). It may be described as 3 ). In addition, these titanium oxides (b 1 , b 2 , b 3 ) may be collectively referred to as surface-treated titanium oxide ( BI ).
[0034]
　The ink composition of the first embodiment, in the ink composition, to the content of the binder resin (A), the surface-treated titanium oxide (B I ratio of the content of) (B I a / A), the solid content mass ratio Then, the range is set to 2.5 to 6.5 (condition 1). The content of surface-treated titanium oxide ( BI ) in the ink composition is the sum of alumina-treated titanium oxide (b 1 ), alumina-silica composite-treated titanium oxide (b 2 ), and ATO-treated titanium oxide (b 3 ). Content.
[0035]
　In the ink composition of the first aspect, by using the surface-treated titanium oxide ( BI ) under the above condition 1, it is possible to form a laser marking layer capable of recording with good visibility. From the viewpoint of enabling better visibility recording, the above ratio ( BI / A) is preferably 2.7 or more, more preferably 3.0 or more, and further preferably 3.0 or more in terms of solid content mass ratio. It is preferably 3.5 or more, and preferably 6.0 or less.
[0036]
　Among the surface-treated titanium oxide ( BI ), alumina-treated titanium oxide (b 1 ) and ATO-treated titanium oxide (b 3 ) are preferable. ATO-treated titanium oxide (b 3 With), since the laser marking layer is easily obtained to enable a better recording of visibility, more preferably. Therefore, when the ink composition contains ATO-treated titanium oxide (b 3 ), the ratio of the content of ATO-treated titanium oxide (b 3 ) to the content of the binder resin (A) (b 3 / A) is calculated. By setting the solid content mass ratio to 1.0 to 6.5 (condition 2), it is possible to form a laser marking layer that enables recording with good visibility. From the viewpoint of enabling better visibility recording, the above ratio (b 3 / A) is preferably 1.2 or more, more preferably 1.5 or more, and further , in terms of solid content mass ratio. It is preferably 2.0 or more, and preferably 6.0 or less.
[0037]
　In the ink composition of the first aspect, at least one of the above conditions 1 and 2 may be satisfied. For example, the ink composition does not contain ATO-treated titanium oxide (b 3 ), but contains either or both of alumina-treated titanium oxide (b 1 ) and alumina-silica composite-treated titanium oxide (b 2 ). In this case, the above condition 1 may be satisfied. Further, the ink composition, surface-treated titanium oxide (B I of), ATO titanium oxide (b 3 if it contains)
[0038]
　Further, when the ink composition contains ATO-treated titanium oxide (b 3 ) and / or both of alumina-treated titanium oxide (b 1 ) and alumina-silica composite-treated titanium oxide (b 2 ). , Only the above condition 1 may be satisfied, only the above condition 2 may be satisfied, or both the above conditions 1 and 2 may be satisfied. When the ink composition contains ATO-treated titanium oxide (b 3 ) and other surface-treated titanium oxide (b 1 and / or b 2 ), ATO-treated titanium oxide (b) so as to satisfy only condition 1. It is preferable to keep the amount of 3 ) used to a small amount because the ink composition can be made cheaper and the laser marking layer which enables recording with good visibility can be formed at a lower cost. For example, in this case, the ratio (b 3 / A) of the content of the ATO-treated titanium oxide (b 3 ) to the content of the binder resin (A) is preferably 0.01 to 0.5, and is 0. It is more preferably 0.01 to 0.3, and further preferably 0.02 to 0.1.
[0039]
The oil absorption of the 　alumina-treated titanium oxide (b 1 ) and the alumina-silica composite-treated titanium oxide (b 2 ) is preferably 15 g / 100 g or more, more preferably 17 g / 100 g or more, and 55 g / 100 g / It is preferably 100 g or less. In the present specification, the oil absorption amount of titanium oxide means the oil absorption amount (g) of the boiled sardine per 100 g of the titanium oxide sample. This oil absorption amount can be measured according to the method specified in JIS K5101-132: 2004.
[0040]
　Further, the ink composition of the second aspect, the titanium oxide (B) is antimony-doped tin oxide which was coating-treated titanium oxide (b 3 and), titanium oxide (b 3 oil absorption of not) 4 ). Then, in the ink composition, to the content of the binder resin (A), ATO titanium oxide (b 3 ) and an oil absorption of 19 g / 100 g or more of titanium oxide (b 4 ratio of the sum of the content of) [(b 3 + B 4 ) / A] is set in the range of 1.0 to 6.5 in terms of solid content mass ratio (Condition 3). With this configuration (condition 3), it is possible to form a laser marking layer that enables recording with good visibility. From the viewpoint of enabling better visibility recording, the above ratio [(b 3 + b 4 ) / A] is preferably 1.5 or more in terms of solid content mass ratio, and more preferably 2. It is 0 or more, more preferably 3.0 or more, and preferably 6.0 or less.
[0041]
　In the ink composition of the second aspect, ATO-treated titanium oxide (b 3 ) and titanium oxide (b 4 ) having an oil absorption of 19 g / 100 g or more are used in combination to be used in combination with ATO-treated titanium oxide (b 4 ). Even if the amount of 3 ) used is suppressed to a small amount, it is possible to form a laser marking layer that enables recording with good visibility. Therefore, it is possible to obtain an ink composition and a target laser marking layer at a lower cost. In this case, the ratio (b 3 / A) of the content of the ATO-treated titanium oxide (b 3 ) to the content of the binder resin (A) is preferably 0.01 to 0.5, preferably 0.01. It is more preferably to 0.3, and further preferably 0.02 to 0.1. Further, titanium oxide (b 4 to the content of), ATO titanium oxide (b 3 ratio of the content of) (b 3 / b 4 a), preferably 0.01 to 0.2 0. It is more preferably 01 to 0.1, and even more preferably 0.01 to 0.05.
[0042]
　The titanium oxide (b 4 ) that can be used in the ink composition of the second aspect is not particularly limited as long as the oil absorption amount is 19 g / 100 g or more, and the titanium oxide that has been subjected to a predetermined surface treatment is used. In addition, titanium oxide that has not been surface-treated (hereinafter, may be referred to as "non-surface-treated titanium oxide") can also be used. The oil absorption of titanium oxide (b 4 ) is preferably 20 g / 100 g or more, and preferably 55 g / 100 g or less.
[0043]
Examples of titanium oxide that has been subjected to a predetermined surface treatment and can be used as 　titanium oxide (b 4 ) having an oil absorption of 19 g / 100 g or more include alumina treatment, silica treatment, zinc treatment, alumina-silica composite treatment, and alumina. -Titanium oxide that has been subjected to surface treatment such as silica-zinc composite treatment and organic treatment can be mentioned. As titanium oxide (b 4 ) , the above-mentioned alumina-treated titanium oxide (b 1 ) having an oil absorption of 19 g / 100 g or more, and the above-mentioned alumina-treated titanium oxide (b 1 ), from the viewpoint of enhancing the effect in combination with ATO-treated titanium oxide (b 3 ), and It is more preferable to use either or both of the above-mentioned alumina-silica composite treated titanium oxide (b 2 ).
[0044]
　As described above, in the ink composition of one embodiment of the present invention, a specific titanium oxide (B) is used in a specific amount within a range satisfying at least one of the above conditions 1 to 3. When all of the above conditions 1 to 3 are not satisfied due to the content of titanium oxide (B) in the ink composition being too small, the non-colored portion when color is generated by irradiation with laser light It may be difficult to obtain a contrast difference between the two, and it may be difficult to record with good visibility. On the other hand, if any of the above conditions 1 to 3 is not satisfied due to the excessive content of titanium oxide (B) in the ink composition, the fluidity of the ink composition is impaired, and the ink composition is used. It may be difficult to apply and it may be difficult to form a laser marking layer.
[0045]
　The crystal structure of titanium oxide (B) used in the ink composition of one embodiment of the present invention may be a rutile type or an anatase type, and a rutile type is more preferable. Further, as the titanium oxide (B), one produced by the sulfuric acid method may be used, or one produced by the chlorine method may be used. The average particle size of titanium oxide (B) is preferably 0.15 to 0.50 μm, more preferably 0.18 to 0.40 μm, and further preferably 0.20 to 0.30 μm. preferable. In the present specification, the average particle size is the particle size at a volume-based integrated value of 50% in the particle size distribution obtained by a particle size distribution measuring machine by a laser diffraction / scattering method.
[0046]
Commercially available products may be used as the 　above-mentioned titanium oxides (b 1 to b 4 ). As the alumina-treated titanium oxide (b 1 ), for example, "JR-600A" (oil absorption amount 19 g / 100 g), "JR-600E" (oil absorption amount 21 g / 100 g), "JR-301" manufactured by Teika Co., Ltd. (Oil absorption amount 18g / 100g), "WP0364" (oil absorption amount 19g / 100g), etc., and "R-630" (oil absorption amount 19g / 100g) and "R-680" under the trade name manufactured by Ishihara Sangyo Co., Ltd. (Oil absorption amount 19 g / 100 g) and the like can be mentioned.
[0047]
Examples of the 　alumina-silica composite treated titanium oxide (b 2 ) include "JR-707" (oil absorption 22 g / 100 g), "JR-708D" (oil absorption 21 g / 100 g), and "JR-708D" (oil absorption 21 g / 100 g), which are trade names manufactured by Teika. "JR-800" (oil absorption 29g / 100g), "JR-806" (oil absorption 21g / 100g), etc., and "R-550" (oil absorption 23g / 100g), "R-550" (oil absorption 23g / 100g), "R-550" (oil absorption 23g / 100g) Examples thereof include "CR-80" (oil absorption amount 20 g / 100 g), "CR-90" (oil absorption amount 21 g / 100 g), and "CR-93" (oil absorption amount 20 g / 100 g).
[0048]
Examples of the 　ATO-treated titanium oxide (b 3 ) include the trade name "Iriotec 8850" (oil absorption amount 50 g / 100 g) manufactured by Merck & Co., Inc. An oil absorption of not less than 19 g / 100 g of titanium oxide (b 4 The), for example, oil absorption listed above surface-treated titanium oxide is 19 g / 100 g or more (B I other products), manufactured by Tayca Corporation The product name is "JA-1" (oil absorption 23g / 100g) and "JA-3" (oil absorption 23g / 100g), and the product name manufactured by Ishihara Sangyo Co., Ltd. is "A-100" (oil absorption 22g / 100g). Examples of non-surface-treated titanium oxide products such as.
[0049]
　The content of titanium oxide (B) is 50 based on the total mass of the solid content of the ink composition from the viewpoint of the cohesive force of the laser marking layer, the adhesion to the substrate, and the color development property by irradiation with laser light. It is preferably ~ 95% by mass. From the viewpoint of obtaining a laser marking layer having appropriate cohesive force and adhesion, the content of titanium oxide (B) in the total solid content of the ink composition is preferably 95% by mass or less, preferably 90% by mass. The following is more preferable. On the other hand, from the viewpoint of obtaining a laser marking layer showing good color development by irradiation with laser light, the content of titanium oxide (B) in the total solid content of the ink composition is preferably 50% by mass or more. , 60% by mass or more, and even more preferably 70% by mass or more.
[0050]
　The ink composition of one embodiment of the present invention can usually contain a solvent (C). Suitable solvents include, for example, ketone solvents, hydrocarbon solvents, ester solvents, alcohol solvents, glycol ether solvents and the like. The solvent to be used can be appropriately selected depending on the material of the base material to which the ink composition is provided, the application in which the base material is used, and the like. The content of the solvent (C) in the ink composition is not particularly limited, and the solvent is contained so as to have an appropriate viscosity according to a method such as printing when forming a laser marking layer using the ink composition. The amount can be adjusted.
[0051]
　Specific examples of the ketone solvent include acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, methylcyclohexanone, diacetone alcohol and the like. Specific examples of the hydrocarbon solvent include toluene, cyclohexane, methylcyclohexane, ethylcyclohexane, dimethylcyclohexane, cyclopentane, methylcyclopentane, ethylcyclopentane and the like. Specific examples of the ester solvent include ethyl acetate, propyl acetate, butyl acetate and the like. Specific examples of the alcohol solvent include methyl alcohol, ethyl alcohol, propyl alcohol, isopropyl alcohol, butyl alcohol and the like. Specific examples of glycol ether solvents include ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, and propylene glycol monomethyl ether acetate. , And propylene glycol monoethyl ether acetate and the like. One of the above solvents may be contained in the ink composition alone or in combination of two or more.
[0052]
　The ink composition may contain various additives. Additives include, for example, dispersants, defoamers, leveling agents, silica, waxes, polyisocyanate-based curing agents, coupling agents, antioxidants, UV absorbers, light stabilizers, surfactants, preservatives, etc. Examples thereof include rust preventives, plasticizers, flame retardants, and color formers.
[0053]
　The ink composition is preferably prepared as a printing ink from the viewpoint that the ink composition is easily provided on the base material to form a laser marking layer. Among them, from the viewpoint of high quality and productivity, it is more preferably prepared as a gravure printing ink, an offset printing ink, a flexographic printing ink, or a screen printing ink, and is prepared as a gravure printing ink. Is even more preferable.
[0054]
　The base material on which the ink composition (laser marking layer) is provided is not particularly limited, and examples of the material thereof include plastic, rubber, ceramics, metal, wood, and paper. In addition, as applications in which the base material is used, for example, various packaging containers containing foods, beverages, pharmaceuticals, quasi-drugs, cosmetics, detergents, chemicals, etc., and various types of films, papers, etc. Examples include packaging materials such as packaging materials. Applications in which the base material is used also include electronic parts, electric parts, electric products, automobile parts, various sheets and cards, and labels and tags provided on the products. The ink composition is preferably used for forming a laser marking layer provided on a packaging material. Suitable substrates for that application include art paper, coated paper, high-quality paper, gravure paper, Japanese paper, paperboard, and synthetic paper and other paper; metal foil such as aluminum foil; plastic film; and one of these. Alternatively, two or more types of laminated bodies and the like can be mentioned. As the base material, it is more preferable to use a base material through which the laser light to be used is transmitted, such as a plastic film.
[0055]
　Examples of the plastic film include polyester films such as polyethylene terephthalate (PET), amorphous polyethylene terephthalate (A-PET), polybutylene terephthalate (PBT), polyethylene naphthalate (PEN), and polylactic acid; low density polyethylene ( LDPE), linear low density polyethylene (LLDPE), high density polyethylene (HDPE), polypropylene (PP) and other polyolefin films; cellophane and other cellulose films; polystyrene (PS) films; ethylene-vinyl acetate copolymer resin films Ethylene-vinyl alcohol copolymer resin film; polyamide film; polycarbonate film; polyimide film; polyvinyl chloride film and the like can be mentioned. For example, both stretched and unstretched plastic films can be used, such as biaxially stretched PP film and non-stretched PP film. Further, a plastic film provided with a metal vapor deposition layer such as aluminum vapor deposition, a plastic film provided with a transparent vapor deposition layer such as alumina and silica can also be used. Further, even if the surface of the plastic film is subjected to various surface treatments such as corona discharge treatment, plasma treatment, frame treatment, solvent treatment, and coating treatment, and various decorations such as printing using colored ink. Good.
[0056]
　As the laser light irradiating the laser marking layer formed from the ink composition, one that can be used for so-called laser printing can be used. Suitable laser light includes YAG laser (wavelength: 1064 nm), YVO 4 laser (wavelength: 1064 nm), fiber laser (wavelength: 1050 to 1090 nm), green laser (wavelength: 532 nm), and UV laser (wavelength: 355 nm). Etc. can be mentioned. Ink composition, it is for laser marking using either laser light of these Preferably, YVO 4 more be a laser, and a laser marking using one or both of the fiber laser preferable.
[0057]

　The packaging material according to the embodiment of the present invention includes a base material and a laser marking layer provided on the base material. The laser marking layer in the packaging material is formed from the above-mentioned laser marking ink composition. The packaging material may include any layer other than the base material and the laser marking layer. Examples of the arbitrary layer include, but are not limited to, a pattern layer, a colored layer, a protective layer, a thin-film deposition layer, and an adhesive layer. Further, the laser marking layer in the packaging material may be provided directly on the surface of the base material, or may be provided via an arbitrary layer such as a pattern layer or a colored layer.
[0058]
　The laser marking layer in the packaging material is formed from the above-mentioned laser marking ink composition. Therefore, the laser marking layer contains the binder resin (A) and the specific titanium oxide (B) under conditions that satisfy at least one of the above-mentioned conditions 1 to 3. The thickness of the laser marking layer is preferably 0.1 to 100 μm, more preferably 0.5 to 20 μm, and even more preferably 1 to 5 μm.
[0059]
　The laser marking layer is preferably formed on a white background having a white hue by containing titanium oxide (B), and the laser light irradiation causes the development of a black hue on the white background. Is preferable. By performing laser marking on such a laser marking layer, the contrast becomes clearer, and it is possible to obtain a record with better visibility.
[0060]
　As the base material in the packaging material, as described above, paper, metal foil, and plastic film, and one or more laminates thereof are preferable, and the above-mentioned various plastic films are more preferable. The thickness of the base material is preferably 5 to 500 μm, more preferably 10 to 100 μm, and even more preferably 10 to 60 μm.
[0061]
　Specific aspects of the wrapping material include, for example, a paper box, a wrapping paper, a wrapping film, a wrapping label, a wrapping bag, and a plastic container such as a plastic case and a plastic bottle. In addition, suitable uses of the packaging material include, for example, food packaging materials, beverage packaging materials, pharmaceutical packaging materials, non-pharmaceutical packaging materials, cosmetic packaging materials, and the like. Of these, food packaging materials and beverage packaging materials are more preferable. More specifically, laminated packaging materials and food trays used for food packaging materials, and shrink packaging labels and the like used for food packaging materials and beverage packaging materials are more preferable.
[0062]
　In the case of a laminated packaging material, it is preferable that a protective layer (sealant film) is provided on the side of the laser marking layer opposite to the base material side. Such a laminated packaging material has a laminated structure including at least a base material, a laser marking layer, and a protective layer in this order. The protective layer makes it possible to prevent peeling and wear of the laser marking layer when the packaging material is laser-marked, when the packaging material is manufactured, and when the packaging material is used. For the protective layer, for example, the same resin material as that described in the above description of the binder resin, the same resin material as that described in the above description of the plastic film can be used, and the above-mentioned group can be used. The material itself can also be used. The protective layer may be provided directly on the laser marking layer, or may be provided via an anchor coating agent, an adhesive, or the like. The thickness of the protective layer is preferably 1 to 300 μm, more preferably 5 to 200 μm, and even more preferably 10 to 100 μm.
[0063]
　The method for producing a packaging material includes a step of providing the above-mentioned ink composition on a base material to form a laser marking layer. This manufacturing method preferably includes a step of preparing an ink composition before the step of forming the laser marking layer.
[0064]
　In the step of preparing the ink composition, a step of kneading the binder resin (A), titanium oxide (B), a solvent (C), and an additive used as needed (meat kneading step) and kneading were performed. It is more preferable to include a step of diluting the ink composition with a solvent to obtain a diluted ink. In the step of preparing the ink composition, for example, a paint shaker, a roll mill (three rolls), a ball mill, a sand mill, an attritor, and other stirrers and dispersers can be used.
[0065]
　Examples of the method of providing the ink composition on the base material in the step of forming the laser marking layer on the base material include methods such as printing, dipping, and spin coating. It is preferable to print the ink composition on the base material from the viewpoint that the ink composition is easily provided on the base material to form the laser marking layer. The formation of the laser marking layer by printing is more preferably performed by gravure printing, offset printing, flexographic printing, or screen printing, and further preferably by gravure printing, from the viewpoint of high quality and productivity. The laser marking layer may be provided on the entire surface of the base material, or may be provided on a part including a desired position for laser marking. In the step of forming the laser marking layer on the base material, a step of printing the ink composition on the base material and then drying it, a step of curing the binder resin (A) in the ink layer, and the like can be performed.
[0066]
　When the above-mentioned laminated packaging material is manufactured, it is preferable that the manufacturing method further includes a step of providing a protective layer on the side of the laser marking layer opposite to the base material side. As a method of providing the protective layer, for example, a liquid composition containing the above-mentioned resin material for forming the protective layer is applied to the side of the laser marking layer opposite to the base material side and cured to form the protective layer. There are ways to do this. Examples of the curing form of the liquid composition include drying, curing by heat, and curing by irradiation with active energy rays such as ultraviolet rays. Further, for example, an anchor coating agent is applied to the side of the laser marking layer opposite to the base material side, dried, and then the above-mentioned resin materials (for example, LDPE, HDPE, PP, etc.) are provided by melt extrusion lamination. It is also possible to form a protective layer. Further, the protective layer is formed by dry lamination on the side of the laser marking layer opposite to the base material side, for example, by applying an adhesive, drying the laser marking layer, and then laminating the above-mentioned paper, metal foil, plastic film, or the like. It can also be provided.
[0067]
　By irradiating the laser marking layer in the packaging material with laser light, color is generated in the laser marking layer, and laser marking can be performed. Suitable laser light, YAG laser, YVO 4 can be cited laser, fiber laser, green laser, and a UV laser. It is preferable to use at least one of the laser beams of these, YVO 4 it is more preferable to use a laser beam that combines one or both lasers and fiber lasers.
[0068]
　Further, YVO 4 when using a laser beam that combines one or both of the lasers and fiber lasers, as is the condition, the scan speed 500 ~ 4000 mm / sec (more preferably 800 ~ 3000 mm / sec), the average output Is more preferably 1 to 30 W (more preferably 1 to 10 W), and the pulse frequency is more preferably 5 to 150 kHz (more preferably 10 to 50 kHz).
[0069]
　Examples of the symbol type applied by laser marking include characters, figures, patterns, barcodes, and two-dimensional codes. Information represented by these symbols includes, for example, product name, manufacturer name, date of manufacture, expiration date, expiration date, expiration date, quality assurance date, lot number, serial number, raw material, ingredient, trademark, and Patterns and the like can be mentioned.
[0070]
　As described in detail above, the laser marking ink composition and packaging material according to the embodiment of the present invention can have the following configurations.
　[1] An ink composition used for forming a laser marking layer, which contains a binder resin (A) and titanium oxide (B) that causes color development in the laser marking layer by irradiation with laser light. titanium oxide (B) is surface-treated titanium oxide with alumina (b 1 ), the surface-treated titanium oxide with alumina and silica (b 2 ), and antimony-doped tin oxide which was coating-treated titanium oxide (b 3 A laser marking ink composition containing at least one surface-treated titanium oxide ( BI ) selected from the group consisting of) and satisfying at least one of the following conditions 1 and 2.
　Condition 1: with respect to the content of the binder resin (A), the said surface-treated titanium oxide (B I ratio of the content of) (B I / A) is, on a solids weight ratio, in 2.5 to 6.5 is there.
　Condition 2: the titanium oxide (B) is at least the titanium oxide (b 3 comprises a) to the content of the binder resin (A), the said titanium oxide (b 3 ratio of the content of) (b 3/ A) is 1.0 to 6.5 in terms of solid content mass ratio.
　[2] The oil absorption of the titanium oxide (b 1 ) surface-treated with the alumina and the titanium oxide (b 2 ) surface-treated with the alumina and silica is 15 to 55 g / 100 g in the above [1]. The described ink composition for laser marking.
　[3] An ink composition used for forming a laser marking layer, which contains a binder resin (A) and titanium oxide (B) that causes color development in the laser marking layer by irradiation with laser light. The titanium oxide (B) is composed of titanium oxide (b 3 ) coated with antimony-doped tin oxide and titanium oxide (b 4 ) having an oil absorption amount of 19 g / 100 g or more other than the titanium oxide (b 3 ). The ratio of the total content of the titanium oxide (b 3 ) and the titanium oxide (b 4 ) to the content of the binder resin (A) [(b 3 + b 4 ) / A] is the solid content mass. An ink composition for laser marking having a ratio of 1.0 to 6.5. 　[4] Titanium oxide (b 4) having an oil absorption of 19 g / 100 g or more.
) Contains one or both of titanium oxide (b 1 ) surface-treated with alumina and titanium oxide (b 2 ) surface-treated with alumina and silica, the laser marking ink according to the above [3]. Composition.
　[5] The ink composition for laser marking according to any one of the above [1] to [4], wherein the binder resin (A) contains either one or both of a polyurethane resin and an acrylic resin.
　[6] A base material and a laser marking layer provided on the base material are provided, and the laser marking layer is formed of the laser marking ink composition according to any one of [1] to [5]. Packaging material.
Example
[0071]
　Hereinafter, the ink composition of one embodiment of the present invention will be described in more detail with reference to Examples and Comparative Examples, but the ink composition is not limited to the following Examples. In the following sentences, the descriptions "part" and "%" are based on mass ("parts by mass" and "% by mass", respectively) unless otherwise specified.
[0072]
In
　Test Example A, an ink composition is prepared assuming application to a laminated packaging material, a laminated printed matter is prepared using the prepared ink composition, and the obtained laminated printed matter is laser-marked. Was performed to evaluate its visibility.
[0073]
[Preparation of binder resin] As
　a binder resin to be contained in the ink composition, a polyurethane resin solution having a solid content of 30% (manufactured by Hitachi Kasei Co., Ltd., trade name "TA24-241L", viscosity: 1,000 mPa · s, contained solvent : Ethyl acetate and isopropyl alcohol, glass transition point: -51 ° C., weight average molecular weight: 40,000) were used.
[0074]
[Preparation of Ink Composition]
(Example A1)
　Alumina-silica composite treated titanium oxide (manufactured by TAYCA, trade name "JR-707", crystal: rutile type, oil absorption: 22 g / 100 g; "titanium oxide 1" 50.0 parts, 30.0 parts of the above polyurethane resin solution (9.0 parts as solid content), and 20.0 parts of a mixed solvent having a volume ratio of ethyl acetate / isopropyl alcohol of 4/1 are mixed. The mixture was kneaded with a paint shaker to obtain an ink composition A1.
[0075]
(Example A2)
　Titanium oxide 1 used in the ink composition A1 is subjected to another alumina-silica composite treated titanium oxide (manufactured by TAYCA Corporation, trade name "JR-708D", crystal: rutile type, oil absorption: 21 g / 100 g). The ink composition A2 was obtained in the same manner as in the preparation of the ink composition A1 except that it was changed to "titanium oxide 2").
[0076]
(Example A3)
　Titanium oxide 1 used in the ink composition A1 is subjected to another alumina-silica composite treated titanium oxide (manufactured by TAYCA Corporation, trade name "JR-800", crystal: rutile type, oil absorption: 29 g / 100 g). The ink composition A3 was obtained in the same manner as in the preparation of the ink composition A1 except that the change was made to "titanium oxide 3").
[0077]
(Example A4)
　Titanium oxide 1 used in the ink composition A1 is subjected to another alumina-silica composite treated titanium oxide (manufactured by TAYCA Corporation, trade name "JR-806", crystal: rutile type, oil absorption: 21 g / 100 g). An ink composition A4 was obtained in the same manner as in the preparation of the ink composition A1 except that it was changed to "titanium oxide 4").
[0078]
(Example A5)
　Titanium oxide 1 used in the ink composition A1 is subjected to alumina-treated titanium oxide (manufactured by TAYCA Corporation, trade name "JR-600A", crystal: rutile type, oil absorption: 19 g / 100 g; "titanium oxide 5". The ink composition A5 was obtained in the same manner as in the preparation of the ink composition A1 except that the change was made to ().
[0079]
(Example A6)
　Titanium oxide 1 used in the ink composition A1 is subjected to alumina-treated titanium oxide (manufactured by TAYCA Corporation, trade name "JR-600E", crystal: rutile type, oil absorption: 21 g / 100 g; "titanium oxide 6". The ink composition A6 was obtained in the same manner as in the preparation of the ink composition A1 except that the change was made to ().
[0080]
(Example A7)
　Titanium oxide 1 used in the ink composition A1 was used as alumina-treated titanium oxide (manufactured by TAYCA Corporation, trade name "WP0364", crystal: rutile type, oil absorption: 19 g / 100 g; "titanium oxide 7". The ink composition A7 was obtained in the same manner as in the preparation of the ink composition A1 except that it was changed to (described).
[0081]
(Example A8)
　Titanium oxide 1 used in the ink composition A1 is subjected to alumina-treated titanium oxide (manufactured by TAYCA Corporation, trade name "JR-301", crystal: rutile type, oil absorption: 18 g / 100 g; "titanium oxide 8". The ink composition A8 was obtained in the same manner as in the preparation of the ink composition A1 except that the change was made to ().
[0082]
(Example A9)
　Titanium oxide 1 used in the ink composition A1 is referred to as ATO-treated titanium oxide (manufactured by Merck, trade name "Iriotec8850", crystal: rutile type, oil absorption: 50 g / 100 g; "titanium oxide 9". The ink composition A9 was obtained in the same manner as in the preparation of the ink composition A1 except that it was changed to (described).
[0083]
(Example A10) The
　amounts of titanium oxide 1 and the mixed solvent used in the ink composition A1 (50.0 parts and 20.0 parts, respectively) were changed to 27.0 parts and 43.0 parts, respectively. An ink composition A10 was obtained in the same manner as in the preparation of the ink composition A1 except for the above.
[0084]
(Example A11) The
　amounts of titanium oxide 1 and the mixed solvent used in the ink composition A1 (50.0 parts and 20.0 parts, respectively) were changed to 54.0 parts and 16.0 parts, respectively. An ink composition A11 was obtained in the same manner as in the preparation of the ink composition A1 except for the above.
[0085]
(Example A12) The
　amounts of titanium oxide 1 and the mixed solvent used in the ink composition A1 (50.0 parts and 20.0 parts, respectively) were changed to 35.0 parts and 35.0 parts, respectively. An ink composition A12 was obtained in the same manner as in the preparation of the ink composition A1 except for the above.
[0086]
(Example A13)
　The titanium oxide 1 was 35.0 parts, the titanium oxide 9 was 0.4 parts, the polyurethane resin solution was 30.0 parts (9.0 parts as a solid content), and the mixed solvent 34. Six parts were mixed, and the mixture was kneaded with a paint shaker to obtain an ink composition A13.
[0087]
(Example A14)
　15.0 parts of the titanium oxide 1, 0.2 parts of the titanium oxide 9, 30.0 parts of the polyurethane resin solution (9.0 parts as a solid content), and 54. Eight parts were mixed, and the mixture was kneaded with a paint shaker to obtain an ink composition A14.
[0088]
(Example A15)
　0.5 part of the above titanium oxide 9, non-surface treated titanium oxide (manufactured by TAYCA, trade name "JA-1", crystal: anatase type, oil absorption: 23 g / 100 g; "titanium oxide 10" (), 30.0 parts of the polyurethane resin solution (9.0 parts as solid content), and 19.5 parts of the mixed solvent are mixed, and the mixture is kneaded with a paint shaker. The ink composition A15 was obtained.
[0089]
(Example A16)
　9.0 parts of the titanium oxide 9, 30.0 parts of the polyurethane resin solution (9.0 parts as a solid content), and 61.0 parts of the mixed solvent are mixed, and the mixture is painted. The meat was kneaded with a shaker to obtain an ink composition A16.
[0090]
(Comparative Example A17) The
　amounts of titanium oxide 1 and the mixed solvent used in the ink composition A1 (50.0 parts and 20.0 parts, respectively) were changed to 15.0 parts and 55.0 parts, respectively. An ink composition A17 was obtained in the same manner as in the preparation of the ink composition A1 except for the above.
[0091]
(Comparative Example A18) The
　amounts of titanium oxide 1 and the mixed solvent used in the ink composition A1 (50.0 parts and 20.0 parts, respectively) were changed to 22.0 parts and 48.0 parts, respectively. An ink composition A18 was obtained in the same manner as in the preparation of the ink composition A1 except for the above.
[0092]
(Comparative Example A19) The
　amounts of titanium oxide 1 and the mixed solvent used in the ink composition A1 (50.0 parts and 20.0 parts, respectively) were changed to 60.0 parts and 10.0 parts, respectively. The ink composition A19 was obtained in the same manner as in the preparation of the ink composition A1 except for the above.
[0093]
(Comparative Example A20) An
　ink composition A20 was obtained in the same manner as in the preparation of the ink composition A1 except that the titanium oxide 1 used in the ink composition A1 was changed to the titanium oxide 10.
[0094]
(Comparative Example A21)
　Titanium oxide 1 used in the ink composition A1 is treated with non-surface treated titanium oxide (manufactured by TAYCA Corporation, trade name "JR", crystal: rutile type, oil absorption: 18 g / 100 g; "titanium oxide 11". The ink composition A21 was obtained in the same manner as in the preparation of the ink composition A1 except that the change was made to ().
[0095]
(Comparative Example A22)
　60.0 parts of the titanium oxide 1, 0.6 parts of the titanium oxide 9, 30.0 parts of the polyurethane resin solution (9.0 parts as a solid content), and the mixed solvent 9. Four parts were mixed, and the mixture was kneaded with a paint shaker to obtain an ink composition A22.
[0096]
(Comparative Example A23)
　50.0 parts of the titanium oxide 11, 0.5 part of the titanium oxide 9, 30.0 parts of the polyurethane resin solution (9.0 parts as a solid content), and the mixed solvent 19. Five parts were mixed, and the mixture was kneaded with a paint shaker to obtain an ink composition A23.
[0097]
(Comparative Example A24)
　8.0 parts of the titanium oxide 9, 30.0 parts of the polyurethane resin solution (9.0 parts as a solid content), and 61 parts of the mixed solvent are mixed, and the mixture is mixed with a paint shaker. The meat was kneaded to obtain an ink composition A24.
[0098]

　For each of the ink compositions obtained in Test Example A, as described below, a diluted ink is prepared, a laminated printed matter is prepared, and the laminated printed matter is laser-marked. The visibility of the laser marking was evaluated.
[0099]
[Preparation of Diluted Inks A1 to 24]
　Each of the obtained ink compositions A1 to 24 is further diluted with a diluting solvent of ethyl acetate (60%) / propyl acetate (20%) / isopropyl alcohol (20%). At 25 ° C, Zahn Cup No. The viscosity was adjusted to 18 seconds in 3 (manufactured by Rigosha) to obtain diluted inks A1 to 24.
[0100]
[Preparation of Laminated Prints A1 to 24]
　For each of the obtained diluted inks A1 to 24, a printed matter was prepared, and then laminated printed matter A1 to 24 was prepared. Specifically, a diluted ink is used on the treated surface side of a corona discharge-treated PET film (trade name "ester E5102", manufactured by Toyobo Co., Ltd., thickness 25 μm) as a base film, and a gravure plate having a plate depth of 35 μm is used. Gravure printed. In this way, a printed matter in which an ink layer (100 mm × 150 mm solid layer, thickness 3 μm) made of diluted ink was formed on the base film was obtained. Then, a polyethyleneimine-based anchor coating agent (“Seikadyne 4100”, manufactured by Dainichiseika Kogyo Co., Ltd.) was applied to the ink layer side of the printed matter and dried to form an anchor coating layer (thickness 0.03 μm). Then, LDPE (trade name "Novatec LC600A", manufactured by Japan Polyethylene Corporation) is melt-extruded into the anchor coat layer as an intermediate layer to melt and extrude an LLDPE film (trade name "TUX FC-D", Mitsui Chemicals Tohcello Co., Ltd.). Made) was laminated. In this way, the laminated printed matter in which the LDPE layer (thickness about 30 μm) and the protective layer (thickness total about 60 μm) of the LDPE layer (thickness about 30 μm) is laminated on the ink layer provided on the base film in the printed matter. Obtained.
[0101]
[Implementation of laser marking]
　Laser marking was performed on each of the obtained laminated printed materials A1 to 24 to obtain recorded materials A1 to 24. Specifically, with respect to the region where the ink layer is provided in the laminated printed matter , the wavelength 1060 is used from the PET film side of the laminated printed matter with a YVO 4 / fiber hybrid laser marker (manufactured by KEYENCE, trade name “MD-X1000”). A recorded material was obtained by irradiating with a laser beam of about 1070 nm. The irradiation pattern of the laser marker was recorded in fine and bold letters of "2017.09.01" (character height: 5 mm). As for the irradiation conditions of the laser marker, the scan speed is set to 1000 mm / sec and the pulse frequency is set to 20 kHz for each pattern, the average output of the fine-character irradiation pattern is 2.6 W, and the average output of the bold-type irradiation pattern is set. It was set to 1.3W. With respect to the obtained recorded materials A1 to 24, the visibility of the recorded characters (numbers) was evaluated as described below.
[0102]
(Visibility)
　The characters (numbers) of "2017.09.01" in the recorded materials A1 to 24 are visually confirmed, and the evaluation criteria (AA to E) shown below are taken into consideration in consideration of the degree of faintness and darkness of the characters. The sharpness of the characters was evaluated accordingly. In the evaluation criteria shown below, "AA", "A", and "B" were set as practically usable levels, and "C", "D", and "E" were set as unusable levels.
AA: There was no noticeable blurring, the letters were dark, and the numbers could be recognized very clearly.
　A: There was no noticeable blurring, the letters were not too thin, and the numbers could be clearly recognized.
　B: The characters were faint and there were thin parts, but the characters could be recognized.
　C: Most of the characters were faint and very thin, so it was difficult to recognize the characters.
　D: The characters were hardly recorded and the characters could not be recognized.
　E: The ink print itself was faint and the characters could not be recognized.
[0103]
　Table 1-1 and Table 1-2 show specific titanium oxide (B) with respect to the amount of solid component used in the ink composition prepared in each example in Test Example A and the content of the binder resin (A) described above. Ratio of content of ATO-treated titanium oxide (b 3 ) to content of titanium oxide (b 4 ) , ratio of content of ( BI / A, b 3 / A, and (b 3 + b 4 ) / A) (B 3 / b 4 ) and the evaluation result of visibility are shown. In the following table, the ratio (B I / A, b 3 for the / A), the ink composition is titanium oxide which is a calculation target of the ratio (respectively B I, b 3 when containing no), " -"Was written. Further, in the table below, for the above ratios ((b 3 + b 4 ) / A, b 3 / b 4 ), the ink composition is the target for calculating the ratio of titanium oxide (b). When the combination of 3 ) and (b 4 ) is not contained, it is written as "-". Further, in the upper part of the table below, the numbers common to the inks (ink composition and diluted ink), printed matter (including laminated printed matter), and recorded matter prepared and used in each example are also shown.
[0104]

[0105]

[0106]
　From the comparison between Examples A1 to 13 and Comparative Examples A17 to 21, the content of the surface-treated titanium oxide ( BI ) is contained and the content of the surface-treated titanium oxide ( BI ) is relative to the content of the binder resin (A). A laser marking layer capable of recording with good visibility can be formed by an ink composition in which the ratio ( BI / A) of is in the range of 2.5 to 6.5 in terms of solid content mass ratio. Was confirmed.
[0107]
　Further, from the results of Examples A9, surface-treated titanium oxide (B I as), ATO titanium oxide (b 3 With), can form a laser marking layer to allow better recording visibility It was confirmed that. Based on this result, as a result of further confirmation experiments by the present inventors, the ratio (b 3 / A) of the content of ATO-treated titanium oxide (b 3 ) to the content of the binder resin ( A) is the solid content mass. It was found that an ink composition having a ratio in the range of 1.0 to 6.5 can form a laser marking layer that enables recording with good visibility (Examples A9 and A16, as well as Comparative Example A24).
[0108]
　Further, from the comparison between Examples A13 to 15 and Comparative Examples A22 to 23, ATO-treated titanium oxide (b 3 ) and titanium oxide (b 4 ) having an oil absorption of 19 g / 100 g or more are contained and the binder resin ( b 4 ) is contained. The ratio of the total content of titanium oxide (b 3 ) and titanium oxide (b 4 ) to the content of A) [(b 3 + b 4 ) / A] is 1.0 to 6.5 in terms of solid content mass ratio. It was confirmed that the laser marking layer capable of recording with good visibility can be formed by the ink composition within the range of. ATO-treated titanium oxide (b 3 ) and an oil absorption of 19 g / 100 g or more of titanium oxide (b 4 By using a combination of), ATO titanium oxide (b 3 be suppressed to a small amount the amount of) good It can be expected that the effect can be obtained and the ink composition and the target laser marking layer can be obtained at a lower cost.
[0109]
In
　Test Example B, an ink composition is prepared assuming application to a shrink packaging label used for PET bottles and the like, and the prepared ink composition is printed on a shrink film as a base material. The obtained printed matter was laser-marked and its visibility was evaluated.
[0110]
[Preparation of Binder Resin] As the binder resin
　to be contained in the ink composition, the polyurethane resin solution having a solid content of 30% and the nitrocellulose resin solution having a solid content of 20% used in Example A above were used. .. In the nitrocellulose resin solution, 20.0 parts of nitrocellulose resin (trade name "DLX30-50", manufactured by Inabata Sangyo Co., Ltd.) is added to 80.0 parts of a solvent in which isopropyl alcohol and ethyl acetate are mixed in equal amounts on a volume basis. The dissolved one was used.
[0111]
[Preparation of Ink Composition]
(Example B1)
　50.0 parts of the titanium oxide 1 which is an alumina-silica composite treated titanium oxide, and 7.5 parts of the polyurethane resin solution in terms of solid content (25.0 in the solution). Part), 2.5 parts of the above nitrocellulose resin solution in terms of solid content (12.5 parts of the solution), and 12.5 parts of a mixed solvent with a volume ratio of methyl ethyl ketone / ethyl acetate / isopropyl alcohol 5/3/2. Then, the mixture was kneaded with a paint shaker to obtain an ink composition B1.
[0112]
(Example B2) The
　amounts of titanium oxide 1 and the mixed solvent used in the ink composition B1 (50.0 parts and 12.5 parts, respectively) were changed to 40.0 parts and 22.5 parts, respectively. The ink composition B2 was obtained in the same manner as in the preparation of the ink composition B1 except for the above.
[0113]
(Example B3) The
　amounts of titanium oxide 1 and the mixed solvent used in the ink composition B1 (50.0 parts and 12.5 parts, respectively) were changed to 60.0 parts and 2.5 parts, respectively. The ink composition B3 was obtained in the same manner as in the preparation of the ink composition B1 except for the above.
[0114]
(Example B4)
　Titanium oxide 1 used in the ink composition B1 was changed to the titanium oxide 2 which is another alumina-silica composite treated titanium oxide, except that the titanium oxide 2 was changed in the same manner as in the preparation of the ink composition B1. An ink composition B4 was obtained.
[0115]
(Example B5) The
　ink composition B5 was prepared in the same manner as in the preparation of the ink composition B1 except that the titanium oxide 1 used in the ink composition B1 was changed to the titanium oxide 5 which is an alumina-treated titanium oxide. Obtained.
[0116]
(Example B6) The
　ink composition B6 was prepared in the same manner as in the preparation of the ink composition B1 except that the titanium oxide 1 used in the ink composition B1 was changed to the titanium oxide 6 which is an alumina-treated titanium oxide. Obtained.
[0117]
(Example B7) The
　ink composition B7 was prepared in the same manner as in the preparation of the ink composition B1 except that the titanium oxide 1 used in the ink composition B1 was changed to the titanium oxide 9 which is the ATO-treated titanium oxide. Obtained.
[0118]
(Example B8)
　50.0 parts of the titanium oxide 1, 2.5 parts of the titanium oxide 9, 7.5 parts of the polyurethane resin solution in terms of solid content (25.0 parts of the solution), and the nitrocellulose. Mix 2.5 parts of the resin solution in terms of solid content (12.5 parts of the solution) and 10.0 parts of a mixed solvent of methyl ethyl ketone / ethyl acetate / isopropyl alcohol in a volume ratio of 5/3/2, and paint the mixture. The meat was kneaded with a shaker to obtain an ink composition B8.
[0119]
(Example B9) The
　amounts of titanium oxide 9 and the mixed solvent used in the ink composition B8 (2.5 parts and 10.0 parts, respectively) were changed to 1.0 part and 11.5 parts, respectively. An ink composition B9 was obtained in the same manner as in the preparation of the ink composition B8 except for the above.
[0120]
(Example B10) The
　amounts of titanium oxide 9 and the mixed solvent used in the ink composition B8 (2.5 parts and 10.0 parts, respectively) were changed to 0.5 parts and 12.0 parts, respectively. The ink composition B10 was obtained in the same manner as in the preparation of the ink composition B8 except for the above.
[0121]
(Example B11) The
　amounts of titanium oxide 9 and the mixed solvent used in the ink composition B8 (2.5 parts and 10.0 parts, respectively) were changed to 0.2 parts and 12.3 parts, respectively. The ink composition B11 was obtained in the same manner as in the preparation of the ink composition B8 except for the above.
[0122]
(Example B12)
　40.0 parts of the titanium oxide 1, 0.5 parts of the titanium oxide 9, 7.5 parts of the polyurethane resin solution in terms of solid content (25.0 parts of the solution), and the nitrocellulose. Mix 2.5 parts of the resin solution in terms of solid content (12.5 parts of the solution) and 22.0 parts of a mixed solvent with a volume ratio of methyl ethyl ketone / ethyl acetate / isopropyl alcohol 5/3/2, and paint the mixture. The meat was kneaded with a shaker to obtain an ink composition B12.
[0123]
(Example B13) The
　amounts of titanium oxide 1 and the mixed solvent used in the ink composition B12 (40.0 parts and 22.0 parts, respectively) were changed to 30.0 parts and 32.0 parts, respectively. The ink composition B13 was obtained in the same manner as in the preparation of the ink composition B12 except for the above.
[0124]
(Example B14) The
　amounts of titanium oxide 1 and the mixed solvent used in the ink composition B12 (40.0 parts and 22.0 parts, respectively) were changed to 20.0 parts and 42.0 parts, respectively. An ink composition B14 was obtained in the same manner as in the preparation of the ink composition B12 except for the above.
[0125]
(Comparative Example B15) The
　amounts of titanium oxide 1 and the mixed solvent used in the ink composition B1 (50.0 parts and 12.5 parts, respectively) were changed to 20.0 parts and 42.5 parts, respectively. Ink composition B15 was obtained in the same manner as in the preparation of ink composition B1 except for the above.
[0126]
(Comparative Example B16) The
　ink composition B16 is the same as the preparation of the ink composition B1 except that the titanium oxide 1 used in the ink composition B1 is changed to the titanium oxide 10 which is a non-surface treated titanium oxide. Got
[0127]
(Comparative Example B17) The
　ink composition B17 is the same as the preparation of the ink composition B1 except that the titanium oxide 1 used in the ink composition B1 is changed to the titanium oxide 11 which is a non-surface treated titanium oxide. Got
[0128]

　For each of the ink compositions obtained in Test Example B, as described below, a diluted ink is prepared, a printed matter is prepared, and the printed matter is laser-marked to perform laser marking. Visibility was evaluated.
[0129]
[Preparation
　of Diluted Inks B1 to 17] Each of the obtained ink compositions B1 to 17 is further diluted with a diluting solvent having a volume ratio of methyl ethyl ketone / ethyl acetate / isopropyl alcohol of 5/3/2 at 25 ° C. Zahn Cup No. The viscosity was adjusted to 18 seconds in 3 (manufactured by Rigosha) to obtain diluted inks B1 to 17.
[0130]
[Preparation of Printed Materials B1 to 17]
　Printed matter B1 to 17 were prepared for each of the obtained diluted inks B1 to 17. Specifically, as a base film, a polyester (PET) -based shrink film (trade name "Space Clean S7042", manufactured by Toyobo Co., Ltd.) having a thickness of 45 μm is gravure with diluted ink and a gravure plate with a plate depth of 40 μm. I printed it. In this way, a printed matter (shrink film printed matter) in which an ink layer (100 mm × 150 mm solid layer, thickness 3 μm) formed by the diluted ink was formed on the base film was obtained.
[0131]
[Implementation of laser marking]
　Laser marking was performed on each of the obtained printed matter B1 to 17 to obtain recorded matter (shrink wrapping label) B1 to 17. Specifically, a laser beam having a wavelength of 1060 to 1070 nm is emitted from the ink layer side with a YVO 4 / fiber hybrid laser marker (manufactured by KEYENCE, trade name “MD-X1000”) to the region where the ink layer is provided. Irradiation was performed to obtain a recorded material. The irradiation pattern of the laser marker was a fine character of "2017.09.01" (character height: 5 mm). As the irradiation conditions of the laser marker, the scan speed was set to 1000 mm / sec, the pulse frequency was set to 20 kHz, and the average output of the irradiation pattern was set to 2.6 W. The visibility (sharpness) of the recorded characters (numbers) of the obtained recorded materials B1 to 17 was evaluated according to the evaluation criteria described in Example A.
[0132]
　Tables 2-1 and 2-2 show specific titanium oxide (B) with respect to the amount of solid component used in the ink composition prepared in each example of Test Example B and the content of the binder resin (A) described above. Ratio of content of ATO-treated titanium oxide (b 3 ) to content of titanium oxide (b 4 ) , ratio of content of ( BI / A, b 3 / A, and (b 3 + b 4 ) / A) (B 3 / b 4 ) and the evaluation result of visibility are shown.
[0133]

[0134]

[0135]
In
　Test Example C, an ink composition was prepared assuming application to a food tray, and the prepared ink composition was printed on a plastic film for a tray as a base material, and the obtained printed matter was obtained. , Laser marking was performed and the visibility was evaluated.
[0136]
[Preparation of binder resin] As
　a binder resin to be contained in the ink composition, an acrylic resin solution having a solid content of 40% (trade name "1LO-449", manufactured by Taisei Fine Chemicals Co., Ltd., solvent: ethyl acetate and isopropyl alcohol) , And a cellulose acetate butyrate (CAB) resin solution having a solid content of 20% was used. The CAB resin solution contains 80.0 parts of a solvent in which isopropyl alcohol and ethyl acetate are mixed in equal amounts on a volume basis, and CAB resin (trade name "CAB381-0.5", manufactured by Eastman Chemical Japan Co., Ltd.) 20.0. The one in which the part was dissolved was used.
[0137]
[Preparation of Ink Composition]
(Example C1)
　40.0 parts of the titanium oxide 1 which is an alumina-silica composite treated titanium oxide, and 9.0 parts of the acrylic resin solution in terms of solid content (22. 5 parts), 1.0 part of CAB resin solution in terms of solid content (5.0 parts of solution), 32.5 parts of mixed solvent with a volume ratio of ethyl acetate / isopropyl alcohol 4/6, and mix the mixture. The ink composition C1 was obtained by kneading with a paint shaker.
[0138]
(Example C2)
　30.0 parts of the titanium oxide 1, 1.0 part of the titanium oxide 9 which is ATO-treated titanium oxide, and 9.0 parts of the acrylic resin solution in terms of solid content (22. 5 parts), 1.0 part of the CAB resin solution in terms of solid content (5.0 parts of the solution), and 41.5 parts of a mixed solvent with a volume ratio of ethyl acetate / isopropyl alcohol of 4/6 are mixed, and the mixture thereof. Was kneaded with a paint shaker to obtain an ink composition C2.
[0139]
(Example C3) The
　amounts of titanium oxide 9 and the mixed solvent used in the ink composition C2 (1.0 part and 41.5 part, respectively) were changed to 2.0 part and 40.5 part, respectively. The ink composition C3 was obtained in the same manner as in the preparation of the ink composition C2 except for the above.
[0140]
(Example C4) The
　amounts of titanium oxide 9 and the mixed solvent used in the ink composition C2 (1.0 part and 41.5 parts, respectively) were changed to 3.0 parts and 39.5 parts, respectively. The ink composition C4 was obtained in the same manner as in the preparation of the ink composition C2 except for the above.
[0141]
(Example C5) The
　amounts of titanium oxide 9 and the mixed solvent used in the ink composition C2 (1.0 part and 41.5 parts, respectively) were changed to 5.0 parts and 37.5 parts, respectively. The ink composition C5 was obtained in the same manner as in the preparation of the ink composition C2 except for the above.
[0142]
(Comparative Example C6) The
　amounts of titanium oxide 1 and the mixed solvent used in the ink composition C1 (40.0 parts and 32.5 parts, respectively) were changed to 10.0 parts and 62.5 parts, respectively. An ink composition C6 was obtained in the same manner as in the preparation of the ink composition C1 except for the above.
[0143]
(Comparative Example C7) The
　amounts of titanium oxide 1 and the mixed solvent used in the ink composition C1 (40.0 parts and 32.5 parts, respectively) were changed to 20.0 parts and 52.5 parts, respectively. An ink composition C7 was obtained in the same manner as in the preparation of the ink composition C1 except for the above.
[0144]

　For each of the ink compositions obtained in Test Example C, as described below, a diluted ink is prepared, a printed matter is prepared, and the printed matter is laser-marked to perform laser marking. Visibility was evaluated.
[0145]
[Preparation of Diluted Inks C1 to 7]
　Each of the obtained ink compositions C1 to 7 was further diluted with a diluting solvent having a volume ratio of ethyl acetate / isopropyl alcohol of 4/6, and the Zahn Cup No. The viscosity was adjusted to 18 seconds in 3 (manufactured by Rigosha) to obtain diluted inks C1 to 7.
[0146]
[Preparation of Printed Materials C1 to 7]
　Printed matter C1 to 7 were prepared for each of the obtained diluted inks C1 to 7. Specifically, a diluted ink is applied to an amorphous polyethylene terephthalate (A-PET) film (trade name "P 0.30 x 640", manufactured by Mineron Kasei Kogyo Co., Ltd.) having a thickness of 300 μm as a base film. Gravure printing was performed using a 40 μm gravure plate. In this way, a printed matter in which an ink layer (100 mm × 150 mm solid layer, thickness 3 μm) made of diluted ink was formed on the base film was obtained.
[0147]
[Implementation of laser marking]
　Laser marking was performed on each of the obtained printed matter C1 to 7 to obtain recorded matter (tray film) C1 to 7. Specifically, a laser beam having a wavelength of 1060 to 1070 nm is emitted from the ink layer side with a YVO 4 / fiber hybrid laser marker (manufactured by KEYENCE, trade name “MD-X1000”) to the region where the ink layer is provided. Irradiation was performed to obtain a recorded material. The irradiation pattern of the laser marker was a fine character of "2017.09.01" (character height: 5 mm). As the irradiation conditions of the laser marker, the scan speed was set to 1000 mm / sec, the pulse frequency was set to 20 kHz, and the average output of the irradiation pattern was set to 2.6 W. The visibility (sharpness) of the recorded characters (numbers) of the obtained recorded materials C1 to 7 was evaluated according to the evaluation criteria described in Example A.
[0148]
　Table 3 shows the amount of the solid component used in the ink composition prepared in each example in Test Example C, and the ratio of the content of the specific titanium oxide (B) to the content of the binder resin (A) described above (B). The ratio of the content of ATO-treated titanium oxide (b 3 ) to the content of I / A, b 3 / A, and (b 3 + b 4 ) / A), titanium oxide (b 4 ) (b 3 / b 4 ) , And the evaluation result of visibility are shown.
[0149]

The scope of the claims
[Claim 1]
　A ink composition used to form the laser marking layer,
　a binder resin (A), the containing titanium oxide to produce a color in the laser marking layer by laser light irradiation (B),
　the titanium oxide ( B) is composed of titanium oxide (b 1 ) surface-treated with alumina, titanium oxide (b 2 ) surface-treated with alumina and silica, and titanium oxide (b 3 ) coated with antimony-doped tin oxide. A 　laser marking ink composition containing at least one surface-treated titanium oxide ( BI ) selected from the group
and satisfying at least one of the following conditions 1 and 2.
　Condition 1: with respect to the content of the binder resin (A), the said surface-treated titanium oxide (B I ratio of the content of) (B I / A) is, on a solids weight ratio, in 2.5 to 6.5 is there.
　Condition 2: The titanium oxide (B) contains at least the titanium oxide (b 3 ), and the ratio of the content of the titanium oxide (b 3 ) to the content of the binder resin (A) (b 3 / A). ) Is 1.0 to 6.5 in terms of solid content mass ratio.
[Claim 2]
The laser marking according to claim 1, wherein the amount of oil absorption of the 　titanium oxide (b 1 ) surface-treated with alumina and the titanium oxide (b 2 ) surface-treated with alumina and silica is 15 to 55 g / 100 g. Ink composition for.
[Claim 3]
　A ink composition used to form the laser marking layer,
　a binder resin (A), the containing titanium oxide to produce a color in the laser marking layer by laser light irradiation (B),
　the titanium oxide ( B) is antimony-doped tin oxide which was coating-treated titanium oxide (b 3 and), the titanium oxide (b 3 titanium oxide (b is oil absorption of not) is 19 g / 100 g or more 4 and a),
　the The ratio of the total content of the titanium oxide (b 3 ) and the titanium oxide (b 4 ) to the content of the binder resin (A) [(b 3 + b 4 ) / A] is the solid content mass ratio. An ink composition for laser marking of 1.0 to 6.5.
[Claim 4]
　Titanium oxide (b 4 ) having an oil absorption of 19 g / 100 g or more is either titanium oxide (b 1 ) surface-treated with alumina or titanium oxide (b 2 ) surface-treated with alumina and silica. The ink composition for laser marking according to claim 3, which comprises both or both.
[Claim 5]
　The laser marking ink composition according to any one of claims 1 to 4, wherein the binder resin (A) contains either one or both of a polyurethane resin and an acrylic resin.
[Claim 6]

　A packaging material 　comprising a base material and a laser marking layer provided on the base material, wherein the laser marking layer is formed of the laser marking ink composition according to any one of claims 1 to 5. ..