JPWO2015072388A1 - UV curable coating varnish composition - Google Patents

Abstract

An object of the present invention is to provide a coater unit provided in an offset printing machine while having good curability even under energy-saving ultraviolet irradiation, low yellowing, and flexibility to overcome cracking of a cured coating film when a substrate is folded. It is providing the ultraviolet curable coating varnish composition characterized by being apply | coated to printed matter by this, and its printed matter. A photopolymerization initiator composition, obtained by reacting a diisocyanate compound having an aromatic ring structure or an alicyclic structure that is 5 to 60% by weight of the total amount and having a weight average molecular weight of 140 to 300 with pentaerythritol triacrylate. An ultraviolet curable coating varnish composition comprising a polymerizable urethane acrylate compound (A) and a polymerizable acrylate monomer (B) other than the above, and coated by a coater unit provided in an offset printing machine .

Description

The present invention is suitable for package ink printing applications such as good curability, low yellowing, flexibility after coating film curing, and paper containers even under energy-saving UV irradiation for reducing power consumption and suppressing CO ₂ emissions. The present invention relates to an ultraviolet curable coating varnish composition that is applied to a printed material by a coater unit provided in an offset printing machine while maintaining productivity.
Furthermore, the present invention relates to a printed material using the composition.

  UV curable coating varnishes that cure under ultraviolet light conditions, among others, are widely used in the field of package printing for toys, paper containers and the like because of the convenience of instantaneous curing characteristics.

  The coating varnish composition, which has a colorless transparent or translucent appearance and substantially does not contain a coloring component, prevents scratches and rubbing of the ink layer by, for example, overprinting on the colored ink. It is also possible to increase the gloss of the printed matter and improve the design. Furthermore, it is possible to change the appearance of varnish gloss, smoothness, texture, etc. by blending colorless inorganic pigments, waxes, resin beads, etc. in the coating varnish, and it is widely used in the applications shown above. ing.

  On the other hand, in recent years, from the viewpoint of environmental protection, energy-saving ultraviolet curable printing that can be cured satisfactorily under a lower irradiation energy condition has attracted attention.

The above-mentioned low irradiation energy conditions refer to general conditions in which the amount of irradiated ultraviolet energy is clearly smaller than before, for example, reducing the power consumption of the UV-emitting lamp or reducing the number of lamps used. In addition to the existing methods of using ultraviolet lamps, including ultraviolet light emitting diode light sources (UV-LEDs) having a peak wavelength at 350 to 420 nm, low power consumption ultraviolet fluorescent lamps, other special ultraviolet lamps, etc. Assuming that an energy-saving type ultraviolet irradiation light source is used, the coating varnish composition of the present invention has the effect of reducing the power consumption required for curing and suppressing CO ₂ emission.

  On the other hand, in energy-saving UV curable printing, for example, irradiation is performed by reducing the UV integrated light amount to 10% to 50% in the conventional UV printing ratio. For example, it is necessary to use a polyfunctional monomer having four or more functionalities.

Furthermore, there are examples in which pentafunctional dipentaerythritol pentaacrylate, hexafunctional pentaerythritol hexaacrylate, or the like is employed as a monomer having higher curability (see, for example, Patent Document 1). However, using polyfunctional acrylates such as pentafunctional and hexafunctional has the advantage of curing with a small amount of accumulated light, but the coating after curing is not flexible enough to be cured when the substrate is folded. There was a problem that the phenomenon of cracks that would cause cracks was likely to occur.
In Patent Document 1, amine-modified acrylate is used as an essential component as a material having both curability and flexibility, and the use of a tertiary amine compound as a means for obtaining better curability is proposed. However, there was an inevitable problem of yellowing with UV curing.

JP2011-1449

  An object of the present invention is to provide a coater unit provided in an offset printing machine while having good curability even under energy-saving ultraviolet irradiation, low yellowing, and flexibility to overcome cracking of a cured coating film when a substrate is bent. It is providing the ultraviolet curable coating varnish composition characterized by being apply | coated to printed matter by this, and its printed matter.

  The present inventors have found that the urethane acrylate concentration of the former can be maintained high by appropriately combining a urethane acrylate having a specific structure that is more excellent in reaction curability and a low-viscosity monomer, and the above-described problems can be achieved. It came to complete.

  That is, the present invention relates to a photopolymerization initiator composition, a diisocyanate compound having an aromatic ring structure or alicyclic structure that is 5 to 60% by weight of the total amount and a weight average molecular weight in the range of 140 to 300 and pentaerythritol tris. An ultraviolet ray containing a polymerizable urethane acrylate compound (A) obtained by reacting an acrylate and a polymerizable acrylate monomer (B) other than the above, and coated by a coater unit provided in an offset printing machine The present invention relates to a curable coating varnish composition.

  The present invention further forms a layer of the described ultraviolet curable coating varnish composition on a substrate or a printing ink layer printed on the substrate, and has a peak wavelength in the range of 350 to 420 nm. The present invention relates to a printed matter obtained by irradiating ultraviolet rays with an ultraviolet light emitting diode light source.

  According to the present invention, in a printing method in which an ultraviolet curable coating varnish composition is applied by an in-line coater unit provided in an offset printing machine, excellent curability, low yellowing, and substrate even under energy-saving ultraviolet irradiation. It is possible to provide an ultraviolet curable coating varnish composition that has flexibility to overcome cracking of a cured coating film when bent.

FIG. 1 is a diagram illustrating coating with an inline coater unit provided in an offset printing machine and curing with an ultraviolet irradiation lamp. FIG. 2 is a view showing a printed matter obtained by irradiating a printed matter developed with the ultraviolet curable coating varnish composition of the present invention with ultraviolet rays to cure the coating varnish layer.

  The ultraviolet curable coating varnish composition of the present invention is a photopolymerization initiator composition, a diisocyanate having a weight average molecular weight of 140 to 300 having an aromatic ring structure or an alicyclic structure that is 5 to 60% by weight of the total amount. It contains a polymerizable urethane acrylate compound (A) obtained by reacting a narate compound and pentaerythritol triacrylate, and a polymerizable acrylate monomer (B) other than the above, and is applied by a coater unit provided in an offset printing machine. Thus, the intended effect of the present invention is achieved.

  As a photopolymerization initiator composition used in the ultraviolet curable coating varnish composition of the present invention, a publicly known compound can be used, but for the purpose of obtaining good curability under the low irradiation energy conditions, It is preferable to use an acylphosphine oxide photopolymerizer.

  Examples of the acylphosphine oxide polymerization initiator include bis- (2,6-dichlorobenzoyl) phenylphosphine oxide, bis- (2,6-dichlorobenzoyl) -2,5-dimethylphenylphosphine oxide, bis- (2,6-dichlorobenzoyl) -4-propylphenylphosphine oxide, bis- (2,6-dichlorobenzoyl) -1-naphthylphosphine oxide, bis- (2,6-dimethoxybenzoyl) phenylphosphine oxide, Bis- (2,6-dimethoxybenzoyl) -2,4,4-trimethylpentylphosphine oxide, bis- (2,6-dimethoxybenzoyl) -2,5-dimethylphenylphosphine oxide, bis- (2,4 , 6-Trimethylbenzoyl) phenyl Bisacylphosphine oxides such as phosphine oxide, 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, 2,6-dimethoxybenzoyl-diphenylphosphine oxide, 2,6-dichlorobenzoyl-diphenylphosphine oxide, Monoacylphosphine oxides such as 2,4,6-trimethylbenzoyl-phenylphosphinic acid methyl ester, 2-methylbenzoyl-diphenylphosphine oxide, pivaloylphenylphosphinic acid isopropyl ester, etc. Among these, 2,4,6-trimethylbenzoyl-diphenylphosphine oxide has a suitable UV curability because it has a UV absorption wavelength that matches the emission wavelength region of the ultraviolet light-emitting diode. It is, and, more preferred from the viewpoint reduced yellowing of the cured coating film.

The content of the acylphosphine oxide photopolymerization initiator in the coating varnish composition is preferably in the range of 5 to 15% by weight with respect to 100% by weight of the nonvolatile content in the coating varnish. If the addition amount is less than 4% by weight, it is difficult to obtain good curability. If the addition amount exceeds 15% by weight, the initiator amount becomes excessive, resulting in a decrease in storage stability due to precipitation of the initiator component. That is not preferable.
The UV curable coating varnish composition of the present invention does not contain volatile components such as water and a low boiling point solvent in principle, and the viscosity of the coating varnish at 25 ° C is No. 4 in the Zahn cup (orifice diameter 4 mm). The outflow time when using is preferably in the range of 10 to 60 seconds, and more preferably in the range of 20 to 50 seconds. When the outflow time is less than 10 seconds, when it exceeds 60 seconds, it is difficult to obtain good varnish coating suitability.

  As an essential component of the ultraviolet curable coating varnish composition of the present invention, a diisocyanate compound having an aromatic ring structure or an alicyclic structure that is 5 to 60% by weight of the total amount of the composition and having a weight average molecular weight of 140 to 300 And a polymerizable urethane acrylate compound (A) obtained by reacting pentaerythritol triacrylate. The content of the polymerizable urethane acrylate compound (A) is preferably in the range of 5 to 60% by weight of the total amount of the composition, and if it is less than 5% by weight, good curability cannot be obtained, and 60% by weight. If it exceeds 50%, it is difficult to keep the viscosity of the coating varnish within the above-mentioned appropriate range. The diisocyanate compound which is a constituent component of the polymerizable urethane acrylate compound (A) preferably has an aromatic ring structure or an alicyclic structure for the purpose of obtaining good curability.

  The weight average molecular weight of the diisocyanate compound having an aromatic ring structure or alicyclic structure is preferably in the range of 140 to 300. When a diisocyanate compound having a molecular weight exceeding 300 is used, it is not preferable because the curability of the polymerizable urethane acrylate compound is lowered. Examples of the diisocyanate compound having an aromatic ring structure constituting the polymerizable urethane acrylate compound (A) and having a weight average molecular weight of 140 to 300 include 2,4-toluene diisocyanate and 2,6-toluene. Diisocyanate, 3,4-toluene diisocyanate (all weight average molecular weight: 174), 4,4′-diphenylmethane diisocyanate, 2,4′-diphenylmethane diisocyanate (all weight average molecular weight: 250) 1,3-xylylene diisocyanate (weight average molecular weight: 188).

  Examples of the diisocyanate compound having an alicyclic structure constituting the polymerizable urethane acrylate compound (A) and having a weight average molecular weight in the range of 140 to 300 include isophorone diisocyanate (weight average molecular weight: 222), 1 , 4-cyclohexylene diisocyanate (weight average molecular weight: 166), 4,4′-methylenebiscyclohexyl diisocyanate (weight average molecular weight: 262), and the like. On the other hand, when an aliphatic diisocyanate compound such as hexamethylene diisocyanate (weight average molecular weight: 168) is used, the cured coating film of the polymerizable urethane acrylate compound becomes too flexible and the curability decreases. It is not preferable.

  Among the diisocyanate compounds having an aromatic ring structure or an alicyclic structure and having a weight average molecular weight of 140 to 300, 2,4-toluene diisocyanate and 2,6-toluene diisocyanate having an aromatic ring structure (Both weight average molecular weights: 174) are more preferable.

  The polymerizable urethane acrylate compound (A) is obtained by subjecting the diisocyanate compound and a polymerizable monomer compound having a hydroxyl group to a urethanization reaction. As the polymerizable monomer compound having a hydroxyl group, pentaerythritol which is a trifunctional acrylate is used. It is preferable to use triacrylate. The methacrylate compound is not preferable in that the curability is inferior, and examples of the polymerizable acrylate having a hydroxyl group other than pentaerythritol triacrylate include compounds such as monofunctional 2-hydroxyethyl acrylate and pentafunctional dipentaerythritol pentaacrylate. However, when 2-hydroxyethyl acrylate is used, the curability of the urethane acrylate compound is inferior, and when dipentaerythritol pentaacrylate is used, the viscosity of the urethane acrylate compound becomes too high. It becomes difficult to keep the viscosity of the product within the above-mentioned preferred range.

  The polymerizable urethane acrylate compound (A) is obtained by reacting a diisocyanate compound having an aromatic ring structure or an alicyclic structure and having a weight average molecular weight in the range of 140 to 300 and pentaerythritol triacrylate, For example, it can be obtained by mixing and reacting at 90 ° C. for about 5 hours. In order to obtain excellent curability, the isocyanate group is preferably urethanated with the hydroxyl group of pentaerythritol triacrylate as much as possible. For example, the ratio of the unreacted isocyanate group is preferably less than 10%.

  The polymerizable urethane acrylate compound (A) can be blended with a thermal polymerization inhibitor in order to prevent thermal polymerization during synthesis and maintain storage stability. Examples of typical thermal polymerization inhibitors include hydroquinone, hydroquinone monomethyl ether, t-butylcatechol, p-benzoquinone, 2,5-t-butylhydroquinone, phenothiazine and the like. It is preferable that the compounding quantity exists in the range of 0.01 to 1 weight% with respect to a urethane acrylate compound (A). Moreover, a publicly known surface smoothing agent, antifoaming agent, viscosity modifier and the like can be added to the ultraviolet curable coating varnish composition of the present invention.

  As a specific example of the polymerizable urethane acrylate compound (A) which is an essential component of the ultraviolet curable coating varnish composition of the present invention, 1 molecule of 2,4-toluene diisocyanate and 2 molecules of pentaerythritol triacrylate were reacted. The chemical structure of the compound is shown in Formula (1), and the chemical structure of the compound obtained by reacting one molecule of 4,4′-diphenylmethane diisocyanate and two molecules of pentaerythritol triacrylate is shown in Formula (2).

  As a means for improving the curability of the ultraviolet curable coating varnish composition, it is effective to increase the concentration of the polymer group (acrylic group) in the composition. For this purpose, 5 to 6 polymer groups are increased in the molecule. Although it is effective to use, for example, dipentaerythritol pentaacrylate or dipentaerythritol hexaacrylate (DPHA) having a density, the cured coating film shrinks tightly due to the effect of reducing the intermolecular distance when the polymer groups react and bond with each other. Tend to be lost and the flexibility is impaired. On the other hand, the polymerizable urethane acrylate compound (A) described in the present invention has six polymer groups in the molecule, and has both a flexible urethane bond and a strong aromatic skeleton or alicyclic skeleton. It is presumed that the balance between flexibility and flexibility is excellent. Furthermore, by using together with a low-viscosity monomer, the compounding concentration of the urethane acrylate compound (A) in the coating varnish can be increased, and the curing performance can be further effectively improved.

  The viscosity of the polymerizable acrylate monomer (B) other than the polymerizable urethane acrylate compound (A) used in the ultraviolet curable coating varnish composition of the present invention is 1 millipascal second (mPa · s) or more and 150 millipascals at 25 ° C. It is less than a second (mPa · s), has a weight average molecular weight in the range of 200 to 600, and contains in the range of 5 to 80% by weight of the total amount. In a composition containing a large amount of a high-viscosity polymerizable acrylate monomer having a viscosity of 150 millipascal seconds (mPa · s) or more, in order to keep the viscosity of the ultraviolet curable coating varnish composition within the above-mentioned appropriate range, It is necessary to relatively reduce the amount of the polymerizable urethane acrylate compound (A) used, and as a result, it becomes difficult to obtain good curability and flexibility. Further, when the weight average molecular weight of the polymerizable acrylate monomer is less than 200, there is a tendency to cause expansion of the rubber roller of the printing press or deterioration of the resin plate, and when it exceeds 600, the reaction curability of the molecule decreases, which is not preferable. .

  Specific examples of the polymerizable acrylate monomer (B) that satisfies the above requirements include PEG200DA (polyethylene glycol diacrylate, viscosity 15 to 35 mPa · s, weight average molecular weight 308), PEG300DA (polyethylene glycol diacrylate, viscosity 20 to 50 mPa · s). , Weight average molecular weight 408), PEG400DA (polyethylene glycol diacrylate, viscosity 45 to 65 mPa · s, weight average molecular weight 508), EO3TMPTA (ethylene oxide average 3 mol modified trimethylolpropane triacrylate, viscosity 50 to 70 mPa · s, weight average Molecular weight 428), DPGDA (dipropylene glycol diacrylate, viscosity 5-30 mPa · s, weight average molecular weight 240), HDDA (hexanediol diacrylate, viscosity) 5 to 15 mPa · s, weight average molecular weight 226), TMPTA (trimethylolpropane triacrylate, viscosity 80 to 120 mPa · s, weight average molecular weight 296), GPTA (propylene oxide average 3 mol modified glycerin triacrylate, viscosity 80 to 120 mPa · s) s, weight average molecular weight 428), PO3TMPTA (propylene oxide average 3 mol modified trimethylolpropane triacrylate, viscosity 70-100 mPa · s, weight average molecular weight 470). Among these, polyethylene glycol diacrylate having a weight average molecular weight in the range of 200 to 600 is preferable in terms of low viscosity and excellent curability. These polymerizable acrylate monomers (B) may be used alone or in combination of two or more.

  Furthermore, the ultraviolet curable coating varnish composition of the present invention may contain a fluorescent brightener (C) having a maximum absorption wavelength in the range of 360 to 400 nm in a range of 0.01 to 1% by weight of the total amount of the composition. I can do it. Examples of the optical brightener include benzoxazal, pyrazoline, stilbene, triazine, thiazole, triazole, oxazole, thiophene, xanthone, and coumarin derivatives. For example, 2,5-thiophenediyl (5-tert-butyl- 1,3-benzoxazole), 4,4′-bis (diphenyltriazinyl) stilbene, stilbenyl-naphthotriazole, 2,2 ′-(thiophendiyl) -bis (tert-butyl-benzoxazole), 2- ( Stilbyl-4)-(naphth-1 ′, 2 ′, 4,5) -1,2,3-triazole-2 ″ -sulfonic acid phenyl ester, 7- (4′-chloro-6 ″ -diethylamino-) 1 ′, 3 ′, 5′-triazin-4′-yl) -amino-3-phenyl-coumarin, 2,5- Bis (6,6′-bis (tert-butyl) -benzoxazol-2-yl) thiophene, 4,4′-bis (benzoxazol-2-yl) stilbene, dibenzoxazolylethylene, and N-methyl- Examples include 5-methoxynaphtholimide, and among these, benzoxazole derivatives are preferable, and 2,5-thiophenediyl (5-tert-butyl-1,3-benzoxazole) is hardened and cured. It is more preferable at the point with little yellowing of a coating film. These fluorescent brighteners (C) may be used alone or in combination of two or more. When the content of the optical brightener (C) is less than 0.01% by weight, good curability and low yellowing cannot be obtained, and when it exceeds 1% by weight, the storage stability is lowered and dissolved. There is a risk that the fluorescent whitening agent component which is not cut off is deposited. The content of the optical brightener (C) is 0.01 to 1% by weight, more preferably 0.1 to 0.7% by weight.

  In addition to the photopolymerization initiator described above, a more suitable curability can be obtained by using a photosensitizer in combination. Examples of the photosensitizer capable of reacting with an ultraviolet light emitting diode of 350 to 420 nm which is an energy saving ultraviolet light source include, for example, thioxanthone, 2,4-diethylthioxanthone, 2-methylthioxanthone, and 2,4-dimethyl among thioxanthone compounds. Examples include thioxanthone, isopropylthioxanthone, 2,4-diisopropylthioxanthone, 2-chlorothioxanthone, 2,4-dichlorothioxanthone, 1-chloro-4-propoxythioxanthone, and the amount used is small in consideration of yellowing expression. Although limited (it is preferably less than 0.5% by weight of the total amount of the ultraviolet curable coating varnish composition), it is possible to suitably improve the curability by using together.

  The printing substrate used in the ultraviolet curable coating varnish composition of the present invention is not particularly limited. For example, catalogs, posters, flyers, CD jackets, direct mails, pamphlets, cosmetics and beverages, pharmaceuticals, toys, equipment, and other packages. Good quality paper, coated paper, art paper, imitation paper, thin paper, cardboard, etc., various synthetic paper, polyester resin, acrylic resin, vinyl chloride resin, vinylidene chloride resin, polyvinyl alcohol, polyethylene, polypropylene, Polyacrylonitrile, ethylene vinyl acetate copolymer, ethylene vinyl alcohol copolymer, ethylene methacrylic acid copolymer, nylon or polylactic acid, polycarbonate film or sheet, cellophane, aluminum foil, etc. It can be mentioned various substrates you are.

  The ultraviolet curable coating varnish composition of the present invention is characterized in that it is applied to a printed material by an inline coater unit provided in an offset printing machine, and is printed on the printing substrate and on the surface of the printing substrate by offset printing. It is possible to obtain good curability and low migration properties regardless of the presence or absence of the underprint offset ink.

  Offset printing machines are manufactured and sold by a large number of printing machine manufacturers. Examples include Heidelberg, Komori Corporation, Mitsubishi Heavy Industries Printing Paper Machine Co., Ltd., Man Roland, Ryobi, and KBA. The present invention can be suitably used in any sheet feeding method, such as a sheet-fed offset printing machine using a printing paper in a form, an offset rotary printing machine using a printing paper in a reel form. More specifically, offset printing machines such as Heidelberg's Speedmaster Series, Komori Corporation's Lislon Series, Mitsubishi Heavy Industries Printing Paper Machinery Co., Ltd.'s Diamond Series, etc. can be mentioned. The product is suitably coated with an in-line coater unit provided in these offset printing machines, and can provide good curability, low yellowing, and flexibility of the cured coating film.

  As the underprint offset ink used in combination with the ultraviolet curable coating varnish composition of the present invention, publicly known and commonly used ultraviolet curable offset ink, oxidation polymerization offset ink, heat drying type (heat set), which are generally manufactured and sold. It is possible to use offset ink, osmotic drying type offset ink, etc., but it is more preferable to select UV curable offset ink in terms of obtaining better curability and gloss, Examples include the Dicure HR ink series (manufactured by DIC Graphics).

  As the varnish coating system using the inline coater unit provided in the offset printing machine, a roll coater system and a chamber coater system are widely used, and the UV curable coating varnish composition of the present invention is suitable for both systems. Although it can be used, a chamber coater is more preferable in that the coating amount of the coating varnish can be more strictly controlled. The chamber coater has a mechanism that can supply coating varnish inside the pores (cells) uniformly carved on the surface of the anilox roll and scrape the anilox roll with a doctor to make the amount of varnish uniform. Is changed, an anilox roll having a different cell volume is used (see FIG. 1).

  The optimum coating thickness of the ultraviolet curable coating varnish composition of the present invention to be applied to a printing substrate and printed matter is preferably in the range of 1 to 8 micrometers in a wet state before ultraviolet irradiation, and is 2 to 6 micrometers. More preferably, it is in the range. When the coating thickness of the varnish is less than 1 micrometer, good gloss cannot be obtained, and when it exceeds 8 micrometers, unevenness (swimming) of the varnish surface is likely to occur, and the UV energy given from the UV irradiation lamp Since a large amount of varnish layer is consumed, it is not preferable to use UV curable offset ink as the base because the ink layer is liable to be hardened.

  The ultraviolet curable coating varnish composition of the present invention is blended with the polymerizable acrylate monomer, polymerizable oligomer, photopolymerization initiator, sensitizer, other additives, etc., as in the conventional ultraviolet curable coating varnish. It is manufactured by stirring and mixing with a mixer or the like.

  Hereinafter, the present invention will be described specifically by way of examples.

[Method for producing coating varnish composition]
According to the composition in Table 1, the ultraviolet curable coating varnishes of Examples 1 and 2 and Comparative Examples 1 to 4 were dispersed and mixed with a mixer.
In addition, BYK-307 (made by Big Kammy Japan Co., Ltd.) which is a polydimethylsiloxane compound as a leveling agent is 0.3% by weight, and 0.2% by weight of Ubitex OB (made by BASF) is used as a fluorescent brightening agent. These were added in common to the Examples and Comparative Examples.

[Method for producing printed matter]
The UV curable coating varnish composition thus obtained was used on a rubber roll and a metal roll of the RI tester by using 0.40 ml of coating varnish using a simple color developing machine (RI tester, manufactured by Toyoe Seiko Co., Ltd.). Then, the color was spread so that it was uniformly applied to the surface area of about 220 cm ^{2 on} the surface of the base material to produce a printed matter. In addition, as the base material, OK Special Art Post + (fixed amount 186 g / m ² , manufactured by Oji Paper Co., Ltd.) was used, and the coating thickness of the coating varnish under these conditions was about 3.5 micrometers. The RI tester is a testing machine that develops ink or coating varnish on paper or film, and can adjust the transfer amount or printing pressure of the ink or coating varnish.

[Curing method using UV lamp light source]
The printed matter after the coating varnish was applied was irradiated with UV to cure the coating varnish. Using a water-cooled metal halide lamp (output 80 W / cm, 1 light) and a UV lamp irradiation device (made by Eye Graphics Co., attached with a cold mirror) equipped with a belt conveyor, the printed matter is placed on the conveyor and directly under the lamp (irradiation distance 11 cm) ). The ultraviolet irradiation amount in each condition was measured using an ultraviolet integrated light meter (UNIMETER UIT-150-A / receiver UVD-C365 manufactured by USHIO INC.).

[Curing method using UV-LED light source]
The coating varnish was cured using a UV-LED irradiation device (ultraviolet light emitting diode irradiation device, manufactured by Panasonic Electric Works Co., Ltd., ANUD8002T01) having an emission wavelength peak of 385 nm on the printed matter after coating varnish application. The printed matter placed on the conveyor was irradiated with ultraviolet rays at an irradiation distance of 1 cm, an output of 100%, and a single lamp so as to pass directly under the UV-LED light source. The ultraviolet irradiation amount in each condition was measured using an ultraviolet integrating light meter (UNIMETER UIT-150-A / light receiver UVD-C365 manufactured by USHIO INC.) In the same manner as the UV lamp light source.

[Evaluation Method of Coating Varnish Composition 1: Curability]
The curability was confirmed by the paper rubbing method immediately after irradiation for scratches on the printed material surface. While changing the conveyor speed (m / min) of the UV lamp irradiation device and the UV-LED irradiation device, the printed matter was irradiated with ultraviolet rays, and immediately after the irradiation, the surface of the varnish-cured coating film was coated with a coated paper (“Oji Paper's“ OK ” The top conveyor plus 57.5 kg, A size ") was repeated, and the fastest conveyor speed (m / min) with no damage when the coated paper was rubbed with force on the cured coating surface was described. Therefore, the faster the conveyor speed, the better the curability of the coating varnish.

[Coating Varnish Composition Evaluation Method 2: Flexibility of Cured Coating Film]
The printed matter was irradiated with ultraviolet rays at a conveyor speed of 40 m / min using a UV lamp irradiation device to cure the coating varnish composition. Thereafter, the back of the printed material was pressed against the corner of the desk (angle 90 °), and both ends of the printed material were gripped by hand and squeezed 10 times. By this evaluation method, a physical load is generated on the cured coating film of the coating varnish composition on the surface of the printed matter, so that the flexibility is evaluated in the following three stages by observing cracks on the cured coating surface after the evaluation. did.
○: Cracks do not occur in the cured coating film, and the flexibility is good.
(Triangle | delta): The micro crack has generate | occur | produced in the cured coating film and a softness | flexibility is medium.
X: A clear crack has occurred in the cured coating film, and the flexibility is poor.

[Coating Varnish Composition Evaluation Method 3: Low Yellowing]
The color change resulting from the discoloration (yellowing) of the cured coating varnish coating immediately after UV irradiation was confirmed and evaluated in the following three stages.
○: No or little color change, and low yellowing is good.
Δ: Some yellowing can be confirmed, and low yellowing is moderate.
X: The color change by yellowing can be confirmed clearly, and low yellowing is inferior.

The numerical values in Table 1 are% by weight.
Various raw materials and abbreviations shown in Table 1 are shown below. The viscosity (mPa · s) is at 25 ° C.

Urethane acrylate 1: reaction product of 2,4-toluene diisocyanate (TDI) and pentaerythritol triacrylate; urethanation reaction of 2 mol of pentaerythritol triacrylate per 1 mol of TDI. Urethane acrylate 2: 4,4'-diphenylmethane Reaction product of diisocyanate (MDI) and pentaerythritol triacrylate; urethanization reaction of 2 mol of pentaerythritol triacrylate per 1 mol of MDI MIRAMER M-600: dipentaerythritol hexaacrylate DPHA (hexafunctional acrylate, 4000 to 7000 mPa · s, weight average molecular weight: 578), manufactured by MIWON, PETA-K: pentaerythritol tetraacrylate PETA (tetrafunctional acrylate, 800 mPa S, weight average molecular weight: 352), manufactured by Daicel-Ornex Co., Ltd. MIRAMER M-410: ditrimethylolpropane tetraacrylate DTMPTTA (tetrafunctional acrylate, 450-750 mPas, weight average molecular weight: 467), manufactured by MIWON, Inc. EBECRYL80 : Amine-modified polyether acrylate (tetrafunctional acrylate, 3000 mPa · s, weight average molecular weight: 1000), MIRAMER M-280 manufactured by Daicel Ornex Co., Ltd. Abbreviated name PEG400DA, (45 to 65 mPa · s, weight average) Molecular weight: 508), manufactured by MIWON, IRGACURE TPO: 2,4,6, -trimethylbenzoyl-diphenyl-phosphine oxide, manufactured by BASF, BYK-307: levelin Agent, polydimethylsiloxane compound, manufactured by Big Chemie Japan, Ubitex OB: fluorescent whitening agent, 2,5-thiophenediyl (5-tert-butyl-1,3-benzoxazole) (benzoxazole derivative), BASF Made by company

(Measurement of weight average molecular weight)
In addition, the measurement of the weight average molecular weight (polystyrene conversion) by GPC in this invention was performed on condition of the following using the Tosoh Corp. HLC8220 system.
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% by weight. Sample injection volume: 100 microliters. Detector: differential refractometer.

  In the UV curable coating varnish composition described in the Examples, good curability was obtained by both UV lamp irradiation and UV-LED lamp irradiation. In addition, by blending each raw material in the range of the above-mentioned weight%, it has good results in low yellowing, which is a necessary characteristic of the present invention, and flexibility to overcome cracks in the cured coating film when the substrate is folded. became.

  In the result of the comparative example, the curability, low yellowing, and flexibility for overcoming the crack of the cured coating film could not be covered.

  The UV coating varnish composition of the present invention and the printed material using the UV coating varnish composition have high design properties such as high gloss, embossed pattern, and hologram pattern transfer in graphic image printing, printed graphics, plastic electronic materials, etc. that require UV curing printing. Can be suitably used in the field of exhibiting.

DESCRIPTION OF SYMBOLS 1 Offset ink printing unit 2 Coater unit 3 Printing base material 4 Chamber 5 Anilox roll 6 Blanket cylinder 7 Pressure cylinder 8 Ultraviolet irradiation device (UV lamp light source or UV-LED light source)
9 Cured coating varnish layer 10 Base materials such as paper and film

Claims (6)

A photopolymerization initiator composition, obtained by reacting a diisocyanate compound having an aromatic ring structure or an alicyclic structure that is 5 to 60% by weight of the total amount and having a weight average molecular weight of 140 to 300 with pentaerythritol triacrylate. An ultraviolet curable coating varnish composition comprising a polymerizable urethane acrylate compound (A) and a polymerizable acrylate monomer (B) other than the above, and coated by a coater unit provided in an offset printing machine . The polymerizable acrylate monomer (B) has a viscosity of less than 150 millipascal seconds (mPa · s) at 25 ° C., a weight average molecular weight of 200 to 600, and a range of 5 to 80% by weight of the total amount. The ultraviolet curable coating varnish composition according to claim 1, which is contained. The ultraviolet curable coating varnish composition according to claim 1 or 2, wherein the diisocyanate compound is toluene diisocyanate and the polymerizable acrylate monomer (A) is polyethylene glycol diacrylate. The ultraviolet curable type according to any one of claims 1 to 3, further comprising an optical brightener (C) having a maximum absorption wavelength in the range of 360 to 400 nm in a range of 0.01 to 1% by weight of the total amount. Coating varnish composition. The ultraviolet curable coating varnish composition according to any one of claims 1 to 4, wherein the optical brightener (C) is a benzoxazole derivative. A layer of the ultraviolet curable coating varnish composition according to any one of claims 1 to 5 is formed on a substrate or a printing ink layer printed on the substrate, and has a thickness of 350 to 420 nm. A printed matter obtained by irradiating ultraviolet rays with an ultraviolet light emitting diode light source having a peak wavelength in a range.

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