JP2008120846A - Ultraviolet-curing type overprint varnish composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain an ultraviolet-curing type varnish composition for forming an overprint layer hardly causing cracks by bending processing, etc., although a packaging material is subjected to bending processing to make a box, etc., when the surface of the packaging material such as a box, etc., is coated/printed with an overprint varnish composition, and an ultraviolet-curing type overprint varnish composition for forming a film having little smell since reduction in the smell of the varnish film is required as much as possible when the packaging material is used in the field of food. <P>SOLUTION: The ultraviolet-curing type varnish composition comprises o-methylbenzoyl benzoate as a photopolymerization initiator and an amine compound as a sensitizer. The ultraviolet-curing type varnish composition comprises further a polyester acrylate and a polyethylene glycol diacrylate so as to reduce film cracks. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an ultraviolet curable overprint varnish composition for providing an overprint layer on the entire printing surface printed with ultraviolet curable ink or partially.

Overprint varnish is a coating agent that is applied or printed for the purpose of protecting the surface of printed matter based on paper, plastic, etc., and improving cosmetics by improving gloss and forming a pattern with the overprint varnish. is there.
Examples of printed materials include packaging materials, paper containers, book covers, catalogs, and postcards. The overprint varnish composition is applied to these prints in whole or in part. It may be applied directly to unprinted paper or plastic film.
It may be applied and printed on the entire surface of the printed material, or may be partially applied and printed so as to form a pattern.
The main purpose of application is to increase the gloss of the surface of the printed material to obtain a cosmetic and high-class feeling, and to protect the surface and prevent scratches.

Since the coated layer is formed on the outermost surface of the printed material, it is desired that the odor due to the components in the varnish composition is small.
In addition, when applied to the surface of a paper container (such as a box or a container), it is not preferable that the overprint layer cracks due to the bending process or the like.
Patent documents 1-3 are mentioned as literature in which art about an overprint varnish composition was described. It should be noted that no literature has been found that deals with the odor of the overprint layer and the problem of cracks.

JP-A-8-27398 JP 2000-327709 A JP 2003-55582 A

When the overprint varnish composition is applied and printed on the surface of a packaging material such as a box, and then subjected to gloss processing, the packaging material is bent to make a box or the like. It is not preferable that cracks occur.
It is an object of the present invention to provide an ultraviolet curable varnish composition that forms an overprint layer that hardly generates cracks by bending or the like.

  When the packaging material is used in the food field, it is natural that the odor of the varnish film needs to be reduced as much as possible. Another object of the present invention is to provide an ultraviolet curable overprint varnish composition that forms a film with less odor.

  As a result of extensive research, the inventors have found that by optimizing the types and addition amounts of photopolymerization initiators, oligomers, and monomers, it is possible to achieve both crack prevention and odor reduction, and complete the present invention. did.

  That is, the ultraviolet curable varnish composition of the present invention preferably contains o-methylbenzoylbenzoate as a photopolymerization initiator and preferably contains an amine compound as a sensitizer in order to reduce the odor of the film.

Furthermore, it is preferable to contain polyester acrylate and polyethylene glycol diacrylate in order to reduce cracks in the surface film due to folding or the like.
Formation of the printing layer with ultraviolet curable ink can be performed using lithographic offset printing, flexographic printing, screen printing, or the like.
A roll coater, a chamber coater, a flexo coater, or the like can be used to form the overprint layer using the ultraviolet curable varnish of the present invention.

  A printed matter that has been gloss-processed using the ultraviolet curable overprint varnish composition of the present invention or a printed matter that has a protective layer formed on its surface has little odor, and cracks are unlikely to occur even when subjected to bending.

Hereinafter, embodiments of the present invention will be described in detail. Unless otherwise specified, all percentages and parts in the specification are based on mass.
The ultraviolet curable overprint varnish composition of the present invention is applied to the surface of a printed material in order to impart gloss to the surface of the printed material or to protect the surface.
The overprint varnish composition can be applied partially or entirely to a substrate such as paper, plastic film, or metal foil, in addition to the printed pattern.
In addition, the overprint varnish composition of this invention does not include the use which forms the underprint layer in the printing surface and apply | coats on it.

In order to improve the residual odor, it is preferable to use a combination of a hydrogen abstraction type photopolymerization initiator and a sensitizer which is an amine compound as a photopolymerization initiator.
Examples of the hydrogen abstraction type photopolymerization initiator include benzophenone, methylbenzophenone, o-methylbenzoylbenzoate, and benzyl, and o-methylbenzoylbenzoate is superior in view of residual odor, price and safety.
Examples of the sensitizer include diethanolamine, 4,4-ethylaminobenzophenone, P-dimethylaminobenzoic acid isoamyl ester, amine-modified polyester acrylate oligomer, amine-modified epoxy acrylate oligomer, and amine-modified acrylate monomer.
Among these, amine-modified polyester acrylate oligomers and amine-modified acrylate monomers are excellent in consideration of residual odor, price, safety, coloring of the UV curable varnish itself and coloring of the cured film.

It is preferable to add o-methylbenzoylbenzoate, which is a photopolymerization initiator, within a range of 0.1 to 20% by mass in the total amount of the ultraviolet curable overprint varnish composition.
Moreover, it is preferable to add the amine modified (polyester) acrylate oligomer and / or amine modified acrylate monomer as a sensitizer within a range of 0.1 to 80% by mass of the total amount of varnish.
In consideration of proper viscosity and fluidity when coating an ultraviolet curable overprint varnish, the sensitizer may be added in the range of 0.1 to 70% by mass in the total amount of varnish. More preferred.

  In order to prevent the cured film from being cracked by a bending process or the like in a box or the like in which the overprint layer is formed with the ultraviolet curable varnish composition of the present invention, the tensile strength is high. It is preferable to use an oligomer or a monomer together.

Examples of the oligomer having a high tensile strength include a polyester acrylate oligomer, an epoxy acrylate oligomer, and a urethane acrylate oligomer.
Similarly, the monomers include pentaerythritol triacrylate, trimethylolpropane triacrylate, trimethylolpropane EO-modified triacrylate, bisphenol A / EO-modified diacrylate, bisphenol F / EO-modified diacrylate, isocyanuric acid EO-modified triacrylate, and the like. It is done. Here, EO represents ethylene oxide.

Considering the tensile strength and the effect as the sensitizer among the above oligomers or monomers, amine-modified (polyester) acrylate oligomers and / or amine-modified acrylate monomers are excellent as oligomers or monomers having high tensile strength. ing.
The total amount of the amine-modified (polyester) acrylate oligomer and / or amine-modified acrylate monomer is preferably added within the range of 0.1 to 80% by mass of the total amount of varnish. In view of proper viscosity and fluidity when coating the ultraviolet curable varnish, it is more preferable to add within a range of 0.1 to 70% by mass.

Examples of the oligomer having a high tensile elongation include urethane acrylate oligomer and polyester acrylate oligomer.
Similarly, examples of the monomer include paracumylphenol EO-modified acrylate, nonylphenol EO-modified acrylate, nonylphenol PO-modified acrylate, polyethylene glycol 300 diacrylate, and polyethylene glycol 400 diacrylate. Note that EO represents ethylene oxide, and PO represents propylene oxide.

Among these, considering the tensile elongation, price, safety, etc., polyethylene glycol 400 diacrylate is excellent as a raw material having a large tensile elongation.
Polyethylene glycol 400 diacrylate is preferably added to the ultraviolet curable varnish within a range of 0.1 to 70% by mass, but when considering proper viscosity and fluidity when coating the varnish, It is more preferable to add within the range of 0.1 to 50% by mass.

The laminated body used for the evaluation test of an Example and a comparative example was produced by the procedure shown below.
<Preparation of base material on which printing layer and underprint layer are formed>
(1) Board paper (UF coated paper 270 g / m 2, manufactured by Oji Paper Co., Ltd.) was used as the substrate.
(2) “Dicure Scepter DT Process Ai N” (Dainippon Ink & Chemicals, Inc.), which is an ultraviolet curable offset ink, is developed on this base material. This corresponds to the print layer.
For color development, a color development apparatus described in JIS K5701-1 Annex 3 (simple color development method) was used. A two-segment roller was used as a color developing rubber roll. The amount of the ultraviolet curable ink was developed by applying 0.150 ml of ink to a rubber roller so that the amount of the ultraviolet curable ink was 1 to 2 g / m @ 2 on the substrate.
(4) Next, the substrate A-1 which is a laminate on which a printed layer was formed was obtained by irradiating and curing ultraviolet rays.

<Formation of overprint layer>
A laminate in which an overprint layer was formed by applying five types of ultraviolet curable overprint varnishes prepared in accordance with the formulation shown in Table 1 to the base material A-1 prepared according to the above procedure and curing it by irradiating with ultraviolet rays. Was made.

The ultraviolet curable overprint varnish shown in Table 1 was prepared by weighing each formulation into a polycup and stirring with a homomixer for about 30 minutes.
Then, using the color developing device described in JIS K5701-1 Appendix 3 (simple color developing method), the UV curable varnish 0. 5 ml was attached to a rubber roller to develop a color on each substrate, and cured by irradiation with ultraviolet rays.
The following evaluation was performed using the base materials of Experimental Examples 1 to 5 obtained by the above procedure. The evaluation results are also shown in Table 1.

<Description of Table 1>
The raw materials used are described below.
Amine-modified polyester acrylate oligomer: EBECRYL 3703 manufactured by Daicel Cytec Co., Ltd.
Polyethylene glycol 400 diacrylate: New Frontier PE-400 manufactured by Daiichi Kogyo Seiyaku Co., Ltd.
Acrylate oligomer A: EBECRYL600 manufactured by Daicel Cytec Co., Ltd.
Acrylate monomer A: M-350 manufactured by Toa Gosei Co., Ltd.
Acrylate monomer B: TPGDA manufactured by Daicel Cytec Co., Ltd.

o-Methylbenzoylbenzoate: OBM-100 manufactured by Daicel Cytec Co., Ltd.
Paraffin wax—Accumist 1204 manufactured by Honeywell.
Silicone ... Kyoeisha Chemical Co., Ltd. Polyflow No. 75.
Photopolymerization initiator A: Irgacure 184 manufactured by Ciba Specialty Chemicals Co., Ltd.
Photopolymerization initiator B: Irgacure 651 manufactured by Ciba Specialty Chemicals Co., Ltd.

<Odor>
A small chopped base material was put in a glass bottle and allowed to stand for 1 hour, then the bottle was opened and the odor was evaluated by a sensory test based on the sense of smell. The evaluation criteria were ◯ for those with little odor and no problems, △ for those with a slight odor, and x for odors that seemed to be problematic.

<Flexibility of coating>
The base material is sandwiched between a pair of molds having an uneven part and capable of being fitted together, and bent to make a streak. The corners of the color-developed product with the uneven pattern were observed with a magnifying glass to compare the presence or absence of cracks in the UV clear cured film.
The evaluation criteria were as follows: ◯ when there were almost no cracks or cracks, △ when the cracks were slightly seen, and x when cracks were observed to be quite problematic.
The mold used has a rectangular parallelepiped block (female mold) in which a groove having a width of 2 mm, a depth of 2 mm, and a length of 100 mm is carved, and a convex portion having a width of 1 mm, a depth of 1 mm, and a length of 100 mm. A rectangular parallelepiped block (male) was used in combination. A base material is placed on a female mold, and a male mold is pressed from above to form uneven stripes on the base material.

Experimental Examples 1 to 3 in Table 1 show that the use of o-methylbenzoylbenzoate as a photopolymerization initiator is preferable for reducing odor.
Experimental examples 4 and 5 show that the combined use of an amine-modified polyester acrylate oligomer which is an oligomer having a high tensile strength and polyethylene glycol 400 diacrylate which is an oligomer having a high tensile elongation increases the flexibility of the film.

  The ultraviolet curable overprint varnish composition of the present invention can be used in a method of applying gloss processing to the surface of a printed material. The printed matter obtained by this method has little odor, and cracks are hardly generated even when it is subjected to a bending process.

Claims (3)

  An ultraviolet curable overprint varnish composition containing o-methylbenzoylbenzoate as a photopolymerization initiator and an amine compound as a sensitizer.   The ultraviolet curable overprint varnish composition according to claim 1, comprising polyester acrylate and polyethylene glycol diacrylate.   The printed matter which formed the overprint layer on the printing layer using ultraviolet curable ink using the ultraviolet curable overprint varnish composition in any one of Claim 1 or Claim 2.