JP2018090309A - Printed object - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a printed object which can maintain a low migration property and yellow discoloration inhibition even if common offset ink of ultraviolet curing type is used which is not designed for especially low migration.SOLUTION: A printed object comprises a base sheet, a hydrogenated ink layer for active energy ray which is stiffened on the base sheet after printing, a transparent coating layer which coats the hydrogenated ink layer for active energy ray. The printed object comprises a hardened object of a transparent ultraviolet curable composition which includes polymeric acrylate monomer where the transparent coating layer is 4 senses or more and photoinitiator of α-hydroxy ketone system where number-average molecular weight is 320 or more and 1400 or less. A film thickness of the transparent coating layer is in the range of 0.5-3 μm, and a detective amount which is detected according to the procedure for showing in the following dissolution test, of aromatic compound where number-average molecular weight is 300 or less, is less than 60 ppb.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a printed matter comprising a substrate, an active energy ray-curable ink layer cured after printing on the substrate, and a transparent coating layer covering the active energy ray-curable ink layer.

  Among active energy ray curable inks, UV curable inks are widely used for food packaging applications such as beverage packs, confectionery, and retort packs because of their convenience and high productivity due to their instantaneous drying characteristics. From the viewpoint of food safety and hygiene, mainly in Europe and the United States, there is a growing trend in which the migration (migration) of ink components, particularly photopolymerization initiators, is becoming a problem. There is a strong demand for improvement.

As a measure for suppressing the migration to encapsulated food, it has been proposed to use a photopolymerization initiator having a relatively large molecular weight or a monomer having a high degree of functional group as a component of the ultraviolet curable ink ( For example, see Patent Documents 1 and 2).
However, a photopolymerization initiator having a large molecular weight is expensive in any case, which increases the price of ink using it.

In offset printing, at least four colors of yellow and red ink are used. However, if low-migration inks are used for all four colors, the cost of raw materials for printed materials will increase further, preventing the spread of low-migration printed materials. It is a factor.
Furthermore, in order to realize low migration, it is necessary to make all of UV offset ink (process 4 colors and special colors), overprint varnish (hereinafter abbreviated as OP varnish), clear varnish, and other low migration type inks. There is also a problem that printing work accompanied by switching is complicated and production efficiency does not increase.

JP2015-155499A JP2015-172171

  An object of the present invention is to provide a printed matter that can maintain low migration and yellowing suppression even when a general ultraviolet curable offset ink not specifically designed for low migration is used.

  The inventors of the present invention have a low migration property by covering an active energy ray-cured ink layer cured after printing with a commonly used ultraviolet curable offset ink with a transparent coating layer such as OP varnish. The present inventors have found that a retained printed matter can be obtained, and have reached the present invention.

That is, the present invention is a printed matter comprising a base material, an active energy ray-curable ink layer cured after printing on the base material, and a transparent coating layer covering the active energy ray-curable ink layer, the transparent coating layer Is a cured product of a transparent ultraviolet curable composition containing a tetrafunctional or higher polymerizable acrylate monomer and an α-hydroxyketone photopolymerization initiator having a number average molecular weight of 320 or more and 1400 or less. A printed material having a number average molecular weight of 300 or less of an aromatic compound detected by the procedure shown in the following dissolution test method in the range of 5 to 3 μm and less than 60 ppb. provide.
As a procedure of the dissolution test method,
1. At least two printed materials are superposed so that the printing surface and the printing back surface are in contact with each other, and are pressed using a hydraulic press machine at a pressing pressure of 40 kg / cm ² and a 25 ° C. atmosphere for 10 days.
2. After forming the printed material after pressurization so that the total amount of ink on the printed surface is 60 mg using the printed material in which the printed back surface is in contact with the printed surface, the volume is 1000 cm so that the entire printed back surface is in contact with the liquid surface. ^3, and the total area of the liquid container inner surface in contact with the contents of 1000 cm ³ solution to prepare a liquid container 600 cm ^2, pour 1000 cm ³ (mixed solution of ethanol 50% by weight and pure water 50 wt%) aqueous ethanol solution Seal.
3. A sealed liquid container is allowed to stand in an atmosphere of 40 ° C. for 10 days, and then an aqueous ethanol solution is taken out from the liquid container, and an aromatic compound having a number average molecular weight of 300 or less contained in the aqueous ethanol solution is determined by liquid chromatography mass spectrometry. It is.

  In the present invention, the α-hydroxyketone photopolymerization initiator is 2-hydroxy-1- {4- [4- (2-hydroxy-2-methyl-propionyl) -benzyl] -phenyl} -2-methyl. -Propan-1-one, oligo (2-hydroxy-2-methyl-1- [4- (1-methylvinyl) phenyl] propanone), 2-hydroxy-1- {4- [4- (2-hydroxy- 2-methylpropionyl) phenoxy] phenyl} -2-methylpropanone, which is at least one selected from the group consisting of printed matter.

  Moreover, this invention relates to the printed matter in which the said transparent ultraviolet curable composition contains the thioxanthone type photoinitiator of the number average molecular weight 300-1400 in the range of 0.1-5 mass% of a composition whole quantity.

  Further, in the present invention, the transparent ultraviolet curable composition contains bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide and / or 2,4,6-trimethylbenzoyl-diphenylphosphine oxide in the total amount of the composition. It is related with the printed matter contained in 0.1-10 mass%.

  In the present invention, the transparent ultraviolet curable composition has an aromatic tertiary amine compound having a number average molecular weight of 400 or more and 1500 or less and having a maximum absorption at a wavelength of 250 to 450 nm in the range of 280 to 340 nm. It is related with the printed matter contained in 0.1-8 mass%.

  Moreover, this invention relates to the printed matter which prints the said active energy ray hardening ink layer and a transparent coating layer in-line.

  Furthermore, this invention relates to the transparent ultraviolet curable composition used for printing of the said transparent coating layer.

  The printed matter of the present invention can provide a printed matter that retains low migration and yellowing suppression even when a general ultraviolet curable offset ink not specifically designed for low migration is used.

As an example of the present invention, when a milk carton is employed as a base material, a printed matter comprising an active energy ray-curable ink layer cured after printing on the base material, and a transparent coating layer covering the active energy ray-curable ink layer FIG. It is a figure which superimposes and presses three printed matter of this invention so that the printing surface of a printed matter and the milk carton back surface where the ink is not developed may contact | connect.

The printed matter of the present invention can be easily and inexpensively produced by ordinary operations using conventional printing equipment, even when using ordinary ultraviolet curable ink that is not specifically designed with low migration in mind. Moreover, the printed material using OP varnish which can be printed with the printing cylinder of an offset printing machine is included as a transparent coating layer which covers the active energy ray hardening ink layer hardened after printing on the base material.
Furthermore, it is also important that the transparent coating layer covering the active energy ray-curable ink layer cured after printing on the substrate does not yellow due to the curing reaction.

The printed matter of the present invention is a printed matter comprising a substrate, an active energy ray-curable ink layer cured after printing on the substrate, and a transparent coating layer covering the active energy ray-curable ink layer, the transparent coating The layer is composed of a cured product of a transparent ultraviolet curable composition containing a polymerizable acrylate monomer having 4 or more functionalities and an α-hydroxyketone photopolymerization initiator having a number average molecular weight of 320 or more and 1400 or less. The purpose is that the detected amount of the aromatic compound having a number average molecular weight of 300 or less, which is within the range of 0.5 to 3 μm and detected by the procedure shown in the following dissolution test method, is less than 60 ppb. The effect of the present invention is achieved.
The procedure of the dissolution test method is as follows.
1. At least two printed materials are superposed so that the printing surface and the printing back surface are in contact with each other, and are pressed using a hydraulic press machine at a pressing pressure of 40 kg / cm ² and a 25 ° C. atmosphere for 10 days.
2. After forming the printed material after pressurization so that the total amount of ink on the printed surface is 60 mg using the printed material in which the printed back surface is in contact with the printed surface, the volume is 1000 cm so that the entire printed back surface is in contact with the liquid surface. ^3, and the total area of the liquid container inner surface in contact with the contents of 1000 cm ³ solution to prepare a liquid container 600 cm ^2, pour 1000 cm ³ (mixed solution of ethanol 50% by weight and pure water 50 wt%) aqueous ethanol solution Seal.
3. After the sealed liquid container is allowed to stand in an atmosphere of 40 ° C. for 10 days, the aqueous ethanol solution is taken out from the liquid container, and the aromatic compound having a molecular weight of 300 or less contained in the aqueous ethanol solution is quantified by liquid chromatography mass spectrometry. .

As a printing substrate used in the printed matter of the present invention, in addition to paper mainly used for food packaging such as liquid beverages such as milk carton paper and retort food, various films and the like are used for paper materials for waterproof and oilproof purposes. Can be used widely, such as synthetic paper and synthetic cardboard.
In addition, when forming an active energy ray-cured ink layer that is cured after printing on a substrate, various printing methods such as a gravure printing method, a flexographic printing method, and an ink jet printing method should be adopted in addition to the offset printing method. These may be combined and printed.
Furthermore, in forming a transparent coating layer covering the active energy ray curable ink layer,
An overprint varnish (OP varnish) that can be printed by a printing cylinder of an offset printing press can be used.

And it is essential that the said transparent coating layer is a hardened | cured material of the transparent ultraviolet curable composition containing the polymerizable acrylate monomer more than tetrafunctional.
Specific examples of the tetrafunctional polymerizable acrylate monomer include ditrimethylolpropane tetraacrylate (DTMPTA), ethylene oxide-modified pentaerythritol tetraacrylate (EO-PETA), and propylene oxide-modified pentaerythritol tetraacrylate (PO-PETA). , Etc. Specific examples of the pentafunctional polymerizable acrylate monomer include dipentaerythritol pentaacrylate, and specific examples of the hexafunctional polymerizable acrylate monomer include dipentaerythritol hexaacrylate. These may be used alone or in combination.

Further, in forming the transparent coating layer of the printed matter of the present invention, the tetrafunctional or higher polymerizable acrylate monomer is a mixture of dipentaerythritol pentaacrylate and dipentaerythritol hexaacrylate, and is a transparent ultraviolet curable composition It is preferable to contain 8% by mass or more of the total amount.
Usually, dipentaerythritol pentaacrylate and dipentaerythritol hexaacrylate are manufactured and sold in the form of a simple substance or a mixture, and the product name is “DPHA (manufactured by Sartomer, ratio of hexaacrylate in the product: almost 100% by mass)” “Aronix M-400 (manufactured by Toagosei Co., Ltd., ratio of pentaacrylate in product: 40-50% by mass)” “Aronix M-402 (manufactured by Toagosei Co., Ltd., ratio of pentaacrylate in product: 30-40% by mass) ) “Aronix M-403 (manufactured by Toagosei Co., Ltd., ratio of pentaacrylate in the product: 50-60% by mass)” “Aronix M-404 (manufactured by Toagosei Co., Ltd., ratio of pentaacrylate in the product: 30-40) % By mass) ”“ Aronix M-405 (manufactured by Toagosei Co., Ltd. "Aronix M-406 (manufactured by Toagosei Co., Ltd., ratio of pentaacrylate in the product: 25-35 mass%)""LUMICURE DPA-600T (Zhangjiagang Dong-A Oil Biochemical Co., Ltd.) "Kayarad DPHA (Nippon Kayaku Co., Ltd.)""SR399 (Sartomer, ratio of pentaacrylate in the product: almost 100% by mass)""MIRAMER M600 (MIWON, hexaacrylate in the product) The mixing ratio of pentafunctional and hexafunctional acrylates is different, but both are preferably used by containing 8% by mass or more of the total amount of the transparent ultraviolet curable composition. be able to.

  Further, it is essential that the transparent coating layer is made of a cured product of a transparent ultraviolet curable composition containing an α-hydroxyketone photopolymerization initiator having a number average molecular weight of 320 or more and 1400 or less.

  When the α-hydroxyketone photopolymerization initiator is less than the number average molecular weight 320, the migration amount tends to increase due to the transfer of the photopolymerization initiator component to the inclusion, and when the number average molecular weight exceeds 1300, the varnish itself Decrease in fluidity, decrease in storage stability due to reprecipitation accompanying crystallization of the photopolymerization initiator, and decrease in film drying property after printing. In addition, the initiator component can be made soluble even if the number average molecular weight exceeds 1300 by chemically bonding a component having no conjugated double bond such as polyhydric alcohols and fatty acids by a method such as esterification. Although it is technically possible to provide an excellent compound, these derivatives having a number average molecular weight of more than 1300 lower the effective component concentration of the initiator in the compound (ratio of conjugated double bonds having ultraviolet absorbing ability). Therefore, it is difficult to obtain sufficient drying properties.

  As the α-hydroxyketone photopolymerization initiator having a number average molecular weight of 320 to 1300, 2-hydroxy-1- {4- [4- (2-hydroxy-2-methyl-propionyl) -benzyl]- Phenyl} -2-methyl-propan-1-one (number average molecular weight: 340.4), oligo (2-hydroxy-2-methyl-1- [4- (1-methylvinyl) phenyl] propanone) (number average Molecular weight: 424.57), 2-hydroxy-1- {4- [4- (2-hydroxy-2-methylpropionyl) phenoxy] phenyl} -2-methylpropanone (number average molecular weight: 342.39), etc. These may be used alone or in combination. 1-hydroxy-cyclohexyl-phenyl-ketone (number average molecular weight: 204.3), 2-hydroxy-2-methyl-1-phenyl-propan-1-one (several) which are the same α-hydroxyketone photopolymerization initiator The average molecular weight: 164.2) is not included in these. In addition, 2,2-dimethoxy-1,2-diphenylethane-1-one (number average molecular weight 256.3) is used in a wide range of colorless and transparent inks, but its use is not preferred because of its low migration property.

In addition to the α-hydroxyketone photopolymerization initiator described above, the phenylketone composition group described in Japanese Patent No. 2514804 in which a polymerizable group is introduced into the initiator molecule also imparts ink drying properties and low migration properties. Available for purpose. For example, in this composition group, 4- (2-acryloyloxyethoxy) phenyl- (2-hydroxy-2-propyl) ketone has been named “Darocur ZLI3331” in the past by Merck (currently BASF). And are available in the present invention.
In addition, a composition (number average molecular weight of about 1100) in which a high molecular weight α-hydroxyketone photopolymerization initiator is introduced and a polymerizable group is introduced is sold by BASF under the name of “Irgacure LEX201” and has excellent low migration performance. Similarly, it can be suitably used in the present invention.

  Furthermore, it is essential that the film thickness of the cured film of the transparent film layer covering the active energy ray-curable ink layer of the printed matter of the present invention is in the range of 0.5 to 3 μm.

  When the thickness of the cured coating is less than 0.5 μm, the coating is not sufficient when the repelling of the underlying active energy ray-cured ink layer occurs, and migration tends to occur. Moreover, when the film thickness of the said cured film exceeds 3 micrometers, the shrinkage | contraction after hardening will become large and it exists in the tendency for a film to peel easily. The transparent ultraviolet curable composition for forming the transparent coating layer preferably has an L-type viscosity value at 25 ° C. in the range of 5 to 50 (Pa · s) for convenience of printing using an offset printer. . When the L-type viscosity value is less than 5 (Pa · s), it is easy to cause troubles that the OP varnish splashes during printing, whereas when the L-type viscosity value exceeds 50 (Pa · s), good printability is obtained. It becomes difficult to obtain a uniform coating film. The L-type viscosity is measured according to a measurement method using an L-type viscometer described in JIS K5701-1.

  Furthermore, a printed matter comprising the substrate of the present invention, an active energy ray-curable ink layer cured after printing on the substrate, and a transparent coating layer covering the active energy ray-curable ink layer is a number in the dissolution test method. It is essential that the detected amount of an aromatic compound having an average molecular weight of 300 or less is less than 60 ppb.

As a procedure of the dissolution test method, firstly, the printed surface of at least two prints obtained is overlapped with a blank paper on the printed back surface where the ink is not developed, and a press pressure of 40 kg / The unreacted components in the cured ink layer are migrated to the back surface of the base white paper by applying pressure for 10 days in an atmosphere of cm ² and room temperature of 25 ° C. (see FIGS. 1 and 2).

Next, using the printed material whose printed back surface is in contact with the printed surface, after forming the printed material after pressurization so that the total ink amount on the printed surface is 60 mg, the entire printed back surface is in contact with the liquid surface. A liquid container having a volume of 1000 cm ³ and a total area of 600 cm ^{2 on} the inner surface of the liquid container in contact with the 1000 cm ³ content liquid is prepared, and an ethanol aqueous solution 1000 cm which is a mixed solution of 50% by mass of ethanol and 50% by mass of pure water ³ was poured and sealed, and the ink component transferred to the back of the white paper was extracted into an aqueous ethanol solution.

  Next, after the sealed liquid container is allowed to stand in an atmosphere of 40 ° C. for 10 days, the aqueous ethanol solution is taken out from the liquid container, and the aromatic compound having a molecular weight of 300 or less contained in the aqueous ethanol solution is quantified by liquid chromatography mass spectrometry. The elution concentration (migration concentration) is evaluated based on the detection amount being less than 60 ppb.

  Furthermore, the said transparent ultraviolet curable composition used for the printed matter of this invention adds the thioxanthone type photoinitiator of the number average molecular weight 300-1400 in the range of 0.1-5 mass% of the composition whole quantity. Also good. The thioxanthone photopolymerization initiator tends to increase the migration amount when the number average molecular weight is less than 300. When the number average molecular weight exceeds 1400, the thioxanthone-based photopolymerization initiator decreases the fluidity of the varnish itself and recycles as the photopolymerization initiator crystallizes. This leads to a decrease in storage stability due to precipitation and a decrease in film drying after printing.

  Examples of the thioxanthone photopolymerization initiator having a number average molecular weight of 300 to 1400 include “Omnipol TX (number average molecular weight: 660)” manufactured by IGM as a high molecular weight thioxanthone photopolymerization initiator, and RaHN. “Genopol TX-1 (number average molecular weight: 820)” manufactured by the company can be used, and these may be used alone or in combination. The same thioxanthone photopolymerization initiator 2,4-diethylthioxanthone (number average molecular weight: 268.3), 2-isopropylthioxanthone (number average molecular weight: 254.3) and the like are not included in these.

  The content of the thioxanthone photopolymerization initiator in the transparent ultraviolet curable composition is preferably in the range of 0.1% to 5% by mass with respect to the total amount of the composition. When the addition amount is less than 0.1% by mass, it is difficult to obtain good drying properties. When the addition amount exceeds 5% by mass, the initiator amount becomes excessive, and the varnish fluidity and low migration performance are similarly impaired. In addition, it is not preferable because it easily yellows.

  Furthermore, you may add the bisacyl phosphine oxide type photoinitiator to the said transparent ultraviolet curable composition used for the printed matter of this invention. In particular, bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide and 2,4,6-trimethylbenzoyl-diphenylphosphine oxide are preferable, and the total amount when either or both are used is transparent ultraviolet curing. It is preferable to use it in the range of 0.1 to 10% by mass of the total amount of the composition.

  If the addition amount is less than 0.1% by mass, there is almost no effect on improving drying property. If the addition amount exceeds 10% by mass, the initiator amount becomes excessive, and further improvement in drying property cannot be expected, and transparent UV curing is possible. It is difficult to dissolve in an aqueous composition, which is not preferable because it causes a decrease in varnish fluidity and a deterioration in storage stability due to precipitation.

Furthermore, the said transparent ultraviolet curable composition used for the printed matter of this invention may add an aromatic tertiary amine compound as a sensitizer. As the aromatic tertiary amine compound, among them, the aromatic tertiary amine compound having a number average molecular weight of 400 or more and 1500 or less and having a maximum absorption at a wavelength of 250 to 450 nm in the range of 280 to 340 nm is the total amount of the transparent ultraviolet curable composition. It is preferable to contain in 0.1-8 mass% of range.
Among them, Rann., Which is a high molecular weight aminobenzoate. "Genopol AB-1 (number average molecular weight: 860)" manufactured by AG, "Ominipol ASA (number average molecular weight: 488-532)" manufactured by IGM, or "Esacure A198 (number average molecular weight: 413) manufactured by Lamberti ) "Is preferable because it has a relatively high molecular weight and is difficult to migrate. Aromatic tertiary amines used for UV curable inks include alkylaminobenzoates such as ethyl-4- (dimethylamino) benzoate (number average molecular weight 193.2), 2- (dimethylamino) ethylbenzoate ( Number average molecular weight 193.2), 2-ethylhexyl-4- (dimethylamino) benzoate (number average molecular weight 277.4), and the like can be mentioned, but it is not preferable because of its relatively low molecular weight and easy migration.

  It is preferable that the content rate in the said transparent ultraviolet curable composition of the above-mentioned aromatic tertiary amine compound exists in the range of 0.1-8 mass% with respect to the composition whole quantity. If the addition amount is less than 0.1% by mass, it is not desirable in that a further improvement in the drying rate cannot be obtained, and even if the addition amount exceeds 8% by mass, the effect of use is not recognized, which is not preferable.

In producing the printed matter of the present invention, the step of forming the active energy ray-curable ink layer and the step of forming the transparent coating layer covering the active energy ray-curable ink layer are printed in a continuous inline manner. I can do it. For example, when UV curable offset printing is taken as an example, an offset PS plate or CTP plate mounted on the rear cylinder is overfilled immediately after forming an ink layer using a general UV curable ink in a printing cylinder of an offset printing press. After forming a transparent coating layer by printing varnish (OP varnish), curing drying by ultraviolet irradiation is performed. In this case, the transparent coating layer can be partially provided according to the image line part of the offset PS plate or the CTP plate, or the transparent coating layer can be provided on the entire surface.
In addition, when producing the transparent coating layer of the printed matter of the present invention with an overprint varnish (OP varnish) by the offset printing method, after forming the active energy ray-curable ink layer, the transparent coating layer is formed offline over time. If the transparent coating layer is immediately formed on-line immediately after forming the active energy ray-curable ink layer, migration can be further suppressed. That is, after printing the active energy ray-curable ink for forming the active energy ray-curable ink layer, after irradiating with ultraviolet rays, print the energy ray-curable ink rather than printing the varnish that forms the transparent coating layer offline. Thereafter, after printing the varnish continuously in-line and then irradiating it with ultraviolet rays, a printed matter with more suppressed migration can be obtained.

  Furthermore, in forming the transparent coating layer of the printed matter of the present invention, the α-hydroxyketone photopolymerization initiator is 1 to 15% by mass of the total amount of the transparent ultraviolet curable composition, and the polymerizable acrylate monomer having 4 or more functional groups. Is preferably contained in the range of 15 to 85% by mass of the total amount of the transparent ultraviolet curable composition.

About the α-hydroxyketone photopolymerization initiator, it is difficult to obtain good drying properties with an addition amount of less than 1% by mass of the total amount of the transparent ultraviolet curable composition, and with an addition amount of more than 15% by mass, This is not preferable because the amount of the initiator becomes excessive and the varnish fluidity and low migration performance are impaired. Further, the content of the above-described tetrafunctional or higher polymerizable acrylate monomer in the transparent ultraviolet curable composition is preferably 15% by mass or more with respect to the total amount of the composition, and if less than 15% by mass, the curability is obtained. Decreases and drying and low migration properties deteriorate.
On the other hand, when the addition amount exceeds 85% by mass, a pentafunctional or hexafunctional polymerizable acrylate monomer has a high viscosity, making it difficult to obtain a suitable viscosity.

  In addition, the transparent coating layer which covers the said active energy ray hardening ink layer of the printed matter of this invention may add the resin oligomer which has a polymeric group as needed. Compared with non-reactive resins (inert resins) that do not have a polymerizable group in the molecule, the reactivity is high, and it is possible to impart more excellent low migration properties. Examples of the resin oligomer having a polymerization group include epoxy acrylate, aliphatic acrylate, polyester acrylate, urethane acrylate and the like. Among them, epoxy acrylate and derivatives thereof are more preferable, and examples thereof include bisphenol A diglycidyl ether diacrylate and derivatives thereof, and bisphenol A diglycidyl ether diacrylate is particularly preferable.

In addition, when the printed matter of the present invention is for a milk container based on milk carton paper, the detected amount of an aromatic compound having a number average molecular weight of 300 or less detected by the procedure shown in the dissolution test method is less than 60 ppb. If present, as a photopolymerization initiator other than the above that can be added to the transparent ultraviolet curable composition used for the transparent coating layer covering the active energy ray-curable ink layer of the printed matter, an appropriate amount of the following photopolymerization initiator is added. May be.
Specifically, benzophenone, 4-methylbenzophenone, methyl 2-benzoylbenzoate, ethyl 4-dimethylaminobenzoate, 2-ethylhexane-1-yl = 4- (dimethylamino) benzoate, 4- (2- Hydroxyethoxy) -2-hydroxy-2-methylpropiophenone, 2-benzyl-2- (N, N dimethylamino) -1- (4-morpholinophenyl) butan-1-one, 2- (dimethylamono) 2- (4-methylbenzyl) -1- (4-morpholinophenyl) butan-1-one, 4,4′-bis (diethylamino) benzophenone, 1-hydroxycyclohexyl phenyl ketone, 2-hydroxy-2-methylpro Piophenone, methylbenzoylformate, 2,2-dimethoxy-2-phenylacetophenone, 2-me 4'-methylthio-2-morpholinopropiophenone, 2,4-diethylthioxanthen-9-one, 4- (4-methylphenylthio) benzophenone, isoamyl 4-dimethylaminobenzoate, benzyl, oxy-phenyl -Acetic acid-2- (2-oxo-2-phenyl-acetoxy-ethoxy) ethyl ester, oxy-phenyl-acetic acid-2- (2-hydroxy-ethoxy) ethyl ester, polybutylene glycol-bis (4 -Benzoylphenoxy) acetate, polyethylene glycol-bis (4-benzoylphenoxy) acetate, 1- [4- (4-benzoylphenyl) phenyl] -2-methyl-2-[(4-methylphenyl) sulfonyl] propane-1 -On etc. are mentioned.

In the transparent ultraviolet curable composition used for the transparent coating layer covering the active energy ray curable ink layer of the printed matter of the present invention, viscosity / fluidity adjustment as a varnish, prevention of misting at the time of printing, penetration into a paper substrate An extender can be added for the purpose of improving physical properties such as prevention and imparting functionality.
Examples of the extender pigments include publicly known organic pigments for coloring. Examples of extender pigments include extender pigments for printing inks described in “Pigment Handbook (edited by the Japan Pigment Technical Association)”. Magnesium, kaolin clay, talc, bentonite, mica, barium sulfate, silica, aluminum hydroxide and the like can be used.

The transparent ultraviolet curable composition used for the transparent coating layer covering the active energy ray-curable ink layer of the printed matter of the present invention is produced by the extender pigment and the polymerizable acrylate in the same manner as the conventional ultraviolet curable ink and varnish. Manufactured by blending monomers, photopolymerization initiators, sensitizers, other additives, etc., and stirring and mixing with a mixer, etc., and if necessary, kneading with a disperser such as a three-roll mill or bead mill Manufactured by.

  The present invention will be described more specifically with reference to examples. Hereinafter, both “parts” and “%” are based on mass.

[Preparation of UV curable offset black ink]
In order to produce an active energy ray curable ink layer in the printed matter of the present invention, a general ultraviolet ray curable offset which is not designed especially considering low migration by blending according to Table 1 and kneading with a three-roll mill. A black ink was prepared.

  Rabene 1060 Ultra, which is carbon black as a coloring pigment, is 16% by mass of the total amount of black ink, 3% by mass of phthalocyanine blue and 2% by mass of dioxazine violet as complementary color components, 2% by mass of talc and 2% by mass of magnesium carbonate as viscosity and fluidity modifiers %, 2% by weight of wax as an auxiliary agent and 1% by weight of a stabilizer solution (a mixture of 10% by weight of p-methoxyphenol and 90% by weight of ethylene oxide-modified pentaerythritol tetraacrylate). Note that phthalocyanine blue and dioxazine violet, which are complementary color components, were blended in a small amount for the purpose of canceling the yellowness exhibited by the carbon black itself and further enhancing the jetness of the ink. Furthermore, 4% by mass of Irgacure 907 as a photopolymerization initiator, 1% by mass of Irgacure 369, 2.5% by mass of EAB-SS as a sensitizer, 10% by mass of acrylate monomer: Aronix M-400, and 20% by mass of SR494NS 34.5 mass% of epoxy acrylate UE-8200T which is an acrylate oligomer was added.

Various raw materials and abbreviations shown in Table 1 are shown below.
-Raven 1060 Ultra: carbon black, average primary particle size 30 nm, specific surface area (NSA) 66 m ² / g, manufactured by Birla Carbon-Phthalocyanine blue: copper phthalocyanine, FASTOGEN BLUE TGR-1, DIC-dioxazine violet: dioxin Oxazine violet, Hoster Palm Violet RL 02, manufactured by Clariant Co., talc: hydrous magnesium silicate, high filler # 5000PJ, manufactured by Matsumura Sangyo Co., Ltd. Magnesium carbonate: basic magnesium carbonate, magnesium carbonate TT, manufactured by Naika Shigyo Co., Ltd., wax: Polyolefin wax, S-381-N1, manufactured by Shamrock, stabilizer solution: 10% by mass of p-methoxyphenol (methoquinone, manufactured by Seiko Chemical Co., Ltd.) and ethylene oxide-modified pentaerythritol Mixed solution of 90% by weight of triacrylate (SR494NS, manufactured by Sartomer) Irgacure 907: 2-methyl-1- (4-methylthiophenyl) -2-morpholinopropan-1-one, manufactured by BASF Irgacure 369: 2-benzyl 2-dimethylamino-1- (4-morpholinophenyl) -butanone-1, number average molecular weight 366.5, manufactured by BASF, EAB-SS: 4,4'-bis (diethylamino) benzophenone, Daido Kasei Kogyo Co., Ltd. Manufactured by Aronix M-400: Mixture of dipentaerythritol pentaacrylate and dipentaerythritol hexaacrylate (ratio of pentaacrylate in the product: 40 to 50% by mass), manufactured by Toagosei Co., Ltd. SR494NS: ethylene oxide modified pentaerythritol tetraac Relate, manufactured by Sartomer, DICLITE UE-8200T: bisphenol A diglycidyl ether diacrylate, manufactured by DIC

[Preparation of offset OP varnish]
In order to produce a transparent coating layer covering the active energy ray-curable ink layer of the printed matter of the present invention, blending according to Tables 2 and 3 and kneading in a three-roll mill, production examples A to E, production comparison In Examples F to J, offset OP varnishes (A to J) were prepared.

[Production Example 1]
Magnesium carbonate 8% by mass, talc 2% by mass, auxiliary wax 2% by mass and stabilizer solution (p-methoxyphenol 10% by mass and ethylene oxide modified pentaerythritol tetraacrylate 90% by mass with respect to the total amount of varnish. 1 wt%, photoinitiator Irgacure 127 (2-hydroxy-1- {4- [4- (2-hydroxy-2-methyl-propionyl) -benzyl] -phenyl} -2-methyl-propane-1 -5 mass% of ON (number average molecular weight: 340.4), acrylate monomer: 10 mass% of Aronix M-400, 17 mass% of SR494NS, and 55 mass% of epoxy acrylate UE-8200T which is an acrylate oligomer were added. The finished varnish was designated as OP Varnish A.

  Similarly, according to Table 2, a varnish was prepared by blending Production Examples B to E, and this was designated as OP Varnishes B to E.

  Next, varnishes of Production Comparative Examples F to J were produced in the same procedure as in the production example according to the formulation shown in Table 3. The varnish produced with the composition of Production Comparative Examples F to J was designated as OP varnishes F to J.

The numerical values in Tables 2 and 3 are mass%.
Various raw materials and abbreviations shown in Tables 2 and 3 are shown below.
・ Calcium carbonate: Precipitated calcium carbonate, Neolite SA-300, manufactured by Takehara Chemical Industries ・ Talc: Hydrous magnesium silicate, High filler # 5000PJ, manufactured by Matsumura Sangyo Co., Ltd. ・ Wax: Polyolefin wax, S-381-N1, Shamrock Product / stabilizer solution: mixed solution of 10% by mass of p-methoxyphenol (methoquinone, manufactured by Seiko Chemical Co., Ltd.) and 90% by mass of ethylene oxide-modified pentaerythritol tetraacrylate (SR494NS, manufactured by Sartomer) Irgacure 127: 2-hydroxy-1 -{4- [4- (2-Hydroxy-2-methyl-propionyl) -benzyl] -phenyl} -2-methyl-propan-1-one, manufactured by BASF
ESACURE KIP150: oligo (2-hydroxy-2-methyl-1- [4- (1-methylvinyl) phenyl] propanone), manufactured by Lamberti Ltd. Omnipol TX: polybutylene glycol-bis (9-oxo-9H-thio Xanthenyloxy) acetate, number average molecular weight 660, IGM, Inc., Irgacure 819: bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide, number average molecular weight 418.5, manufactured by BASF, Inc., Irgacure 184: 1-hydroxy -Cyclohexyl-phenyl-ketone,
Number average molecular weight 204.3, manufactured by BASF, Irgacure 651: 2,2-dimethoxy-1,2-diphenylethane-1-one, number average molecular weight 256.3, manufactured by BASF, SPEDCURE DETX: 2,4-diethylthioxanthone , Number average molecular weight: 268.3, manufactured by Lambson
Aronix M-400: a mixture of dipentaerythritol pentaacrylate and dipentaerythritol hexaacrylate (ratio of pentaacrylate in the product: 40 to 50% by mass), manufactured by Toagosei Co., Ltd. SR494NS: ethylene oxide modified pentaerythritol tetraacrylate, Sartomer, MIRAMER M-3130: Ethylene oxide modified trimethylolpropane triacrylate, MIWON, DICLITE UE-8200T: Bisphenol A diglycidyl ether diacrylate, DIC, Genopol AB-1: Poly (ethylene glycol) bis Dimethylaminobenzoate, number average molecular weight 860, manufactured by RAHN AG, Photocure EDB: ethyl-4- (dimethylamino) ben Benzoate, the number average molecular weight 193.24, EUTEC CHEMICAL Co., Ltd.

(Measurement of number average molecular weight)
In addition, the measurement of the number average molecular weight (polystyrene conversion) by GPC in this invention was performed on condition of the following using the HLC8220 system by Tosoh Corporation.
Separation column: 4 TSKgelGMH _HR- N manufactured by Tosoh Corporation are used. Column temperature: 40 ° C. Moving layer: Tetrahydrofuran manufactured by Wako Pure Chemical Industries, Ltd. Flow rate: 1.0 ml / min. Sample concentration: 1.0 mass%. Sample injection volume: 100 microliters. Detector: differential refractometer.

[Printing of UV curable offset black ink]
The UV curable offset black ink obtained in the above procedure was uniformly stretched on the rubber roll and metal roll of the RI tester using a simple color developing machine (RI tester, manufactured by Toyoe Seiko Co., Ltd.), and milk carton paper (polyethylene laminated paper, The color was developed so as to be uniformly applied to the surface of Tetra Rex (manufactured by Tetra Pak Co., Ltd.) to produce a printed matter. The black density was confirmed to be 1.7 with a densitometer SpectroEye manufactured by X-rite. The RI tester is a test machine that develops ink on paper or film, and can adjust the amount of ink transferred and the printing pressure.

[Example 1: OP varnish color]
As Example 1, immediately after the color development of the UV curable offset black ink, OP varnish A was immediately applied to the black ink using a simple color developing machine (RI tester, manufactured by Toyoe Seiko Co., Ltd.) in the same manner as the black ink. Colored.

[Drying method using UV lamp light source]
The printed matter after the application of OP varnish A was irradiated with ultraviolet rays to cure and dry the black ink and the varnish film. Using a UV irradiation device equipped with a water-cooled metal halide lamp (output 80 W / cm1 light) and a belt conveyor (made by Eye Graphics Co., Ltd., with a cold mirror), the printed material is placed on the conveyor and passes directly under the lamp (irradiation distance 11 cm). I let you. The ultraviolet irradiation amount in each condition was measured using an ultraviolet integrated light quantity system (UNIMETER UIT-150-A / receiver UVD-C365 manufactured by Ushio Electric Co., Ltd.) and used as a standard of curability.

[Calculation of film thickness of OP varnish cured film]
The film thickness L (μm) of the cured film of OP varnish was calculated by the following formula.
L = W / T / A · 10000
Here, L is the film thickness (μm) of the cured film, W is the mass (g) of OP varnish on the printed material, T is the density of OP varnish (g / cm ³ ), and A is OP varnish developed. Area (cm ² ). The mass W of the OP varnish on the printed material was determined from the difference between the mass of the printed material before OP varnish color development and the mass of the printed material after the OP varnish color-dried. The density T of the OP varnish was calculated from the mass when the OP varnish was filled in a syringe having a volume of 2 cm ³ . The area A where OP varnish was developed was obtained by actually measuring the area. In Example 1, W = 0.087 g, T = 1.2 g / cm ³ , A = 600 cm ² , and the OP varnish film thickness L was 1.2 μm.

[Migration forced test]
Three printed materials obtained in Example 1 were prepared, and the three printed materials were superposed so that the printed surface of the printed material was in contact with the white paper on the back side of the print that was not developed, and the pressing pressure was 40 kg / cm ² using a hydraulic press. Then, pressurization was performed for 10 days in an atmosphere at room temperature of 25 ° C., and unreacted components in the cured ink layer were migrated to the back surface of the base white paper.

[Examples 2 to 7: OP varnish color rendering / drying / pressing / film thickness calculation]
As shown in Table 4, with respect to Examples 2 to 7, using OP varnishes A to E, the ink varnish was developed from the top of the ink ink immediately after the ink ink was developed in the same manner as in Example 1. The dried printed material was dried with an ultraviolet lamp under the same conditions, and the finished printed matter was similarly pressed with a hydraulic press. Moreover, the film thickness of the OP varnish cured film of the obtained printed matter was calculated in the same procedure as in Example 1. For Examples 6 and 7, the amount of OP varnish used for color development was adjusted, and printed matter having a cured coating film thickness of OP varnish of 0.5 μm and 3.0 μm, respectively, was produced.

[Comparative Examples 1 to 5: OP Varnish Coloring / Drying / Pressing / Film Thickness Calculation]
As Comparative Examples 1 to 5, following the same procedure as in Example 1, immediately after the ink ink was developed, OP varnishes F to J were immediately developed from the top of the ink ink, then dried with an ultraviolet lamp, and finished. The printed matter was pressed in the same manner with a hydraulic press. Moreover, the film thickness of the OP varnish cured film of the obtained printed matter was calculated in the same procedure as in Example 1.

[Comparative Example 6: Calculation of color spreading, drying, pressing, and film thickness of OP varnish assuming offline]
Further, as Comparative Example 6, five sheets of the UV curable offset black ink color product prepared in paragraph [0059] were dried by an ultraviolet lamp in the same procedure as in Example 1, and the printed surface of the printed material was produced. Then, 5 sheets were stacked so that the white paper on the back side of the print that was not developed was in contact, and pressed using a hydraulic press machine at a press pressure of 40 kg / cm ² and a room temperature of 25 ° C. for 24 hours. Next, the middle three of the five color products were taken out, and the OP varnish A was developed on each of the color developed products by an IR tester in the same procedure as in Example 1, and the same conditions were applied. And dried with an ultraviolet lamp, and the finished printed matter was pressed in the same manner with a hydraulic press. Moreover, the film thickness of the OP varnish cured film of the obtained printed matter was calculated in the same procedure as in Example 1.

[Comparative Example 7: Printed product without varnish transparent coating layer]
The color-cured product of UV-curable offset black ink prepared in paragraph [0059] is dried with an UV lamp under the same conditions as in Example 1 without covering with OP varnish, and the finished printed product is printed with a hydraulic press. Pressed in the same way.

[Comparative Examples 8 and 9: OP Varnish Coloring, Drying, Pressing, Calculation of Film Thickness]
As Comparative Examples 8 and 9, following the same procedure as in Example 1, immediately after the ink ink was developed, OP varnish A was immediately developed from above the ink ink, and then dried with an ultraviolet lamp. The amount of OP varnish used for color development was adjusted, and printed materials having a cured film thickness of OP varnish of 0.2 μm and 4.0 μm were produced. In Comparative Example 9, since a crack occurred in the cured film, further evaluation was stopped. In Comparative Example 8, the finished printed material was pressed in the same manner as in Example 1 with a hydraulic press.

[Quantification of aromatic compound having number average molecular weight of 300 or less]
Next, for the middle one of the three sheets stacked in the hydraulic press in Examples 1 to 7 and Comparative Examples 1 to 8, the volume is 1000 cm ³ so that the entire printed back surface is in contact with the liquid level, and A liquid container having a total area of 600 cm ^{2 on} the inner surface of the liquid container that comes into contact with the 1000 cm ³ content liquid is prepared, and 1000 cm ³ of an ethanol aqueous solution, which is a mixed solution of 50% by mass of ethanol and 50% by mass of pure water, is poured and sealed. The ink component transferred to the back surface was extracted into an aqueous ethanol solution.

[Evaluation method for printed matter 1: Migration]
The sealed liquid container prepared using each printed matter was allowed to stand in a 40 ° C. atmosphere for 10 days, and then the ethanol aqueous solution was taken out of the liquid container, and the number average molecular weight contained in the ethanol aqueous solution by liquid chromatography mass spectrometry. An aromatic compound having a molecular weight of 300 or less was quantified, and the evaluation was made according to the following three-stage criteria based on the total amount of the aromatic compound having a number average molecular weight of 300 or less.

○: Less than 30 ppb.
Δ: 30 ppb or more and less than 60 ppb.
X: It is 60 ppb or more.

[Method 2 for evaluating printed matter: curability]
The curability was confirmed by the paper rubbing method immediately after irradiation for scratches on the printed material surface. The printed matter was irradiated with ultraviolet rays while changing the conveyor speed (m / min) of the UV irradiation apparatus, and immediately after irradiation, the surface of the varnish cured coating film was coated on paper (“OK Topcoat Plus 57.5 kg, Oji Paper Co., Ltd., A The fastest conveyor speed with no scratches when the coated paper was rubbed vigorously against the surface of the cured coating was described. Therefore, the faster the conveyor speed, the better the curability of the coating varnish.

[Evaluation Method for Printed Material 3: Yellowing]
The color change resulting from the discoloration (yellowing) of the varnish cured film after the ultraviolet irradiation was visually evaluated in the following three stages.

○: No or almost no color change Δ: Slight yellowing can be confirmed ×: Color change due to yellowing can be clearly confirmed

  Tables 4 and 5 show the evaluation results.

  The printed matter of the present invention had good results that had sufficient curability, suppressed yellowing, and low migration. In addition, as a procedure for producing the printed matter of the present invention, migration of an active energy ray-curable ink layer and a printed matter printed inline with a transparent coating layer can be suppressed more than a printed matter printed off-line.

  The active energy ray-curable offset ink composition of the present invention and printed materials using the same are widely used for sanitary, cosmetics and pharmaceutical packaging and filling applications, in addition to toys and food packaging materials that emphasize safety and hygiene. Can be done.

DESCRIPTION OF SYMBOLS 1 Milk carton base material 2 Active energy ray hardening ink layer 3 Transparent coating layer

Claims (7)

A printed material comprising a base material, an active energy ray-curable ink layer cured after printing on the base material, and a transparent coating layer covering the active energy ray-curable ink layer, wherein the transparent coating layer has a functionality of 4 or more. It consists of a cured product of a transparent ultraviolet curable composition containing a polymerizable acrylate monomer and an α-hydroxyketone photopolymerization initiator having a number average molecular weight of 320 or more and 1400 or less, and the thickness of the cured film is 0.5 to 3 μm. A printed material, wherein the detected amount of an aromatic compound having a number average molecular weight of 300 or less, which is within the range and is detected by the procedure shown in the following dissolution test method, is less than 60 ppb.

1. At least two printed materials are superposed so that the printing surface and the printing back surface are in contact with each other, and are pressed using a hydraulic press machine at a pressing pressure of 40 kg / cm ² and a 25 ° C. atmosphere for 10 days.
2. After forming the printed material after pressurization so that the total amount of ink on the printed surface is 60 mg using the printed material in which the printed back surface is in contact with the printed surface, the volume is 1000 cm so that the entire printed back surface is in contact with the liquid surface. ^3, and the total area of the liquid container inner surface in contact with the contents of 1000 cm ³ solution to prepare a liquid container 600 cm ^2, pouring aqueous ethanol 1000 cm ³ (ethanol 50% by weight mixed solution of pure water 50 wt%) Seal.
3. After the sealed liquid container is allowed to stand in a 40 ° C. atmosphere for 10 days, the aqueous ethanol solution is taken out of the liquid container, and the aromatic compound having a number average molecular weight of 300 or less contained in the aqueous ethanol solution is quantified by liquid chromatography mass spectrometry.
The α-hydroxyketone photopolymerization initiator is 2-hydroxy-1- {4- [4- (2-hydroxy-2-methyl-propionyl) -benzyl] -phenyl} -2-methyl-propane-1- ON, oligo (2-hydroxy-2-methyl-1- [4- (1-methylvinyl) phenyl] propanone), 2-hydroxy-1- {4- [4- (2-hydroxy-2-methylpropionyl) The printed matter according to claim 1, which is at least one selected from the group consisting of phenoxy] phenyl} -2-methylpropanone.
The printed matter according to claim 1 or 2, wherein the transparent ultraviolet curable composition contains a thioxanthone photopolymerization initiator having a number average molecular weight of 300 or more and 1400 or less in a range of 0.1 to 5% by mass of the total amount of the composition.
The transparent ultraviolet curable composition contains bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide and / or 2,4,6-trimethylbenzoyl-diphenylphosphine oxide in a total amount of 0.1 to 10%. The printed matter according to claim 1, which is contained in a mass% range.
The transparent ultraviolet curable composition has a number average molecular weight of 400 or more and 1500 or less, and an aromatic tertiary amine compound having a maximum absorption at a wavelength of 250 to 450 nm in the range of 280 to 340 nm. The printed matter according to any one of claims 1 to 4, which is contained in a mass% range.
The printed matter according to any one of claims 1 to 5, wherein the active energy ray-curable ink layer and the transparent coating layer are printed in-line.
  The transparent ultraviolet curable composition used for printing of the transparent coating layer as described in any one of Claims 1-6.

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