JP7392225B2 - Electron beam curable composition, food packaging material and manufacturing method thereof - Google Patents

Description

Embodiments of the present invention relate to an electron beam curable composition, and more particularly to an electron beam curable composition that can be suitably used as an electron beam curable overcoat varnish. Other embodiments of the present invention relate to a food packaging material having a cured coating film of an electron beam curable composition on the surface layer, and a method for producing the food packaging material.

In recent years, active energy has been used in the printing industry from the viewpoints of shortening process time through instant drying, reducing environmental impact by not containing volatile components (Non-VOC), and achieving strong coating film properties through crosslinking reactions. The use of line curing technology is expanding. For example, inks and varnishes that utilize ultraviolet curing or electron beam curing have been put into practical use for various purposes. However, with regard to inks or varnishes intended for use as food packaging materials, migration of low molecular weight components such as polymerization initiators into encapsulated foods (hereinafter referred to as migration) has been seen as a problem, and improvements are being sought.

The ultraviolet curing type reaction type requires a polymerization initiator, but the electron beam curing type reaction type uses a high-energy electron beam and therefore does not require a photopolymerization initiator. Therefore, from the viewpoint of improving the problem of migration, electron beam curable compositions can be preferably used as inks or varnishes used in applications such as food packaging materials. However, typical electron beam curable compositions, like ultraviolet ray curable compositions, contain (meth)acrylate monomers as a main component, and are likely to suffer from migration problems due to low molecular weight (meth)acrylate monomers. Therefore, further studies are required to improve migration.

Generally, in food packaging materials, the printed surface printed with ink or varnish does not come into direct contact with food (non-food contact). The main migration mechanisms in the structure of the food packaging material described above are penetration, in which the components in the coating film permeate the substrate, and set-off, which occurs when the coating surface comes into contact with the non-printing surface (back surface) of the substrate. The influence of both factors must be evaluated comprehensively. When an electron beam curable composition is used as an ink or varnish, the surface of the coating film has good curability, so penetration of the former is the main factor.

Effective methods for suppressing migration due to penetration include increasing the film thickness of the base material itself, applying a base material with high barrier properties, and introducing a complete barrier layer such as aluminum foil, silica, and alumina vapor deposition. However, these methods are not practical from the viewpoint of reducing the amount of plastic used as an environmental measure in recent years and from the viewpoint of recyclability. In particular, highly recyclable polyolefin films (such as polyethylene or polypropylene) have a relatively low glass transition temperature, and therefore have low barrier properties and low migration suppression effects.
For this reason, it is desired to develop an electron beam curable composition itself to be used as an ink or varnish as a technique for suppressing migration from a printed surface with ink or varnish.

Regarding migration in food packaging materials, various regulations are known that have been established to ensure the safety of food packaging. Among these, the Swiss Ordinance RS817.023.21 Annex 10 establishes a positive list (regulations of usable raw materials) for packaging materials including non-food contact inks and varnishes, and further specifies the permissible raw materials for each raw material. The amount of migration (SML) is regulated. The regulatory standards in the Swiss Federal Ordinance are extremely strict, but in recent years, these regulatory standards have become an important indicator as a global standard for food packaging materials due to the increasing safety consciousness of consumers.

On the other hand, in the field of food packaging materials, consideration is being given to replacing the back-print lamination structure with a front-print structure. Packaging materials with a back-printed lamination structure exhibit the protective function required by the contents by laminating a plurality of films together with an adhesive to form a film layer. In such a configuration, the printed surface is sandwiched between film layers and the film is the outermost surface, so the ink coating is not required to have physical properties such as strength. On the other hand, in front-printed packaging materials, the ink coating is the outermost surface of the packaging material, so an overcoat varnish is generally applied to protect the ink coating.

As overcoat varnishes used for food packaging materials, solvent or water-based heat-drying overcoat varnishes are the mainstream. However, when using the above-described heat-drying overcoat varnish, it is difficult to obtain sufficient coating strength to be applicable to various printing systems in-line or offline.
On the other hand, when an active energy ray-curable composition is used as an overcoat varnish, a desired coating film strength can be easily obtained. However, as mentioned above, improvement in migration is desired in conventional active energy ray-curable overcoat varnishes. In addition, front-print packaging materials having a conventional overcoat varnish coating on the outermost surface tend to be inferior in gloss than back-print packaging materials whose outermost surface is a film. Therefore, from the viewpoint of improving the appearance and design of packaging materials, there is a need for an overcoat varnish that is resistant to flickering and can form a coating film with excellent gloss. Furthermore, from the viewpoint of suitability for post-processing and suitability for filling contents, packaging materials with excellent slip properties are required.

On the other hand, Patent Document 1 discloses a technique for promoting electron beam curing and suppressing migration of low molecular weight acrylate monomers by adding a polyol. Additionally, Patent Document 2 discloses a technique for improving coating film properties such as curability, adhesion, and scratch resistance by adding dimethylpolysiloxane to an electron beam-curable overcoat varnish.

International Publication No. 2020/012157 Japanese Patent Application Publication No. 2020-147730

However, none of these techniques is at a fully satisfactory level in terms of migration, repellency, and gloss, and further study is desired.
Therefore, in view of the above-mentioned situation, one embodiment of the present invention provides an electron beam curable composition that improves migration, is resistant to repelling, and can form a coating film with excellent gloss. Another embodiment of the present invention provides a food packaging material with excellent slip properties and a method for producing the same, using the electron beam curable composition.

As a result of extensive studies, the present inventors have found that the above problems can be solved by constructing the electron beam curable composition described below, and have completed the present invention. That is, embodiments of the present invention relate to the following. However, the present invention is not limited to the following description, and includes various embodiments.

One embodiment includes one or more (meth)acrylate compounds (A) containing a propylene oxide (PO)-modified (meth)acrylate (A1) having three or more functional groups, and satisfies the following (1) and (2). The present invention relates to an electron beam curable composition.
(1) In each of the one or more (meth)acrylate compounds (A), the content of the (meth)acrylate compound having a molecular weight of less than 500 is less than 25% by mass based on the total mass of the composition.
(2) The content of the propylene oxide (PO) modified (meth)acrylate (A1) having three or more functional groups is 15% by mass or more based on the total mass of the composition.
In one embodiment, the electron beam curable composition preferably has a viscosity at 25°C of 700 mPa ·s or less.

The electron beam curable composition of the above embodiment preferably further contains resin beads (B) having an average particle diameter of 0.5 to 6.0 μm. The content of the resin beads (B) is preferably less than 5.0% by mass based on the total mass of the electron beam curable composition.

The propylene oxide (PO) modified (meth)acrylate (A1) having a functional group number of 3 or more includes PO modified trimethylolpropane triacrylate, PO modified glyceryl triacrylate, PO modified pentaerythritol tri(meth)acrylate, and PO modified isocyanuric acid triacrylate. Consisting of (meth)acrylate, PO-modified pentaerythritol tetra(meth)acrylate, PO-modified ditrimethylolpropane tetra(meth)acrylate, PO-modified dipentaerythritol penta(meth)acrylate, and PO-modified dipentaerythritol hexa(meth)acrylate. It is preferable that at least one kind selected from the group is included.

In the electron beam curable composition of the above embodiment, the (meth)acrylate compound (A) preferably further contains ethylene oxide (EO) modified (meth)acrylate having 3 or more functional groups.

It is preferable that the electron beam curable composition of the above embodiment further contains an acrylic leveling agent.

It is preferable that the electron beam curable composition of the above embodiment further contains synthetic amorphous silica.

It is preferable that the electron beam curable composition of the above embodiment does not substantially contain a photopolymerization initiator.

The electron beam curable composition of the above embodiment is preferably used as an electron beam curable overcoat varnish.

The electron beam curable composition of the above embodiment is preferably used to form a surface layer of a food packaging material.

One embodiment relates to a food packaging material that includes a base material and a surface layer provided on the base material, where the surface layer is made of a cured coating film of the electron beam curable composition of the above embodiment.

In the food packaging material of the above embodiment, the surface layer is made of a cured coating film of the electron beam curable composition of the above embodiment containing one or more (meth)acrylate compounds (A) and resin beads (B). A food packaging material,
The ratio (b/t) of the average particle diameter b of the resin beads (B) in the cured coating film to the coating amount t of the electron beam curable composition forming the cured coating film is 0.5 to 2. .0 is preferable.

In one embodiment, the electron beam curable composition of the above embodiment containing one or more (meth)acrylate compounds (A) and resin beads (B) is applied onto a substrate to form a coating film. curing the coating film with an electron beam to form a surface layer consisting of a cured coating film,
In forming the surface layer, the ratio (b/t) of the average particle diameter b of the resin beads (B) in the cured coating film to the coating amount t of the electron beam curable composition forming the cured coating film. is 0.5 to 2.0, and relates to a method for producing food packaging materials.

According to one embodiment of the present invention, it is possible to provide an electron beam curable composition that improves migration, is less prone to repelling, and can form a coating film with excellent gloss. Another embodiment of the present invention can provide a food packaging material with excellent slip properties and a method for producing the same using the electron beam curable composition.

Embodiments of the present invention will be described in detail below. However, the constituent elements, conditions, etc. described below are examples of embodiments of the present invention. Therefore, the present invention is not limited to these contents as long as it does not go beyond the gist of the following description and the effects of the invention can be obtained. Further, unless otherwise specified, "parts" means "parts by mass" and "%" means "% by mass."

1. Electron Beam Curable Composition One embodiment of the present invention includes one or more (meth)acrylate compounds (A) containing a propylene oxide-modified (meth)acrylate (A1) having three or more functional groups, and the following (1) The present invention relates to an electron beam curable composition that satisfies (2) and (2).
(1) In each of the one or more (meth)acrylate compounds (A), the content of the (meth)acrylate compound having a molecular weight of less than 500 is less than 25% by mass based on the total mass of the composition.
(2) The content of the propylene oxide-modified (meth)acrylate having three or more functional groups is 15% by mass or more based on the total mass of the composition.

The constituent components of the electron beam curable composition will be explained below.
<(meth)acrylate compound (A)>
An electron beam curable composition that is an embodiment of the present invention has a (meth)acrylate compound (A) as a main component. In one embodiment, the content of the (meth)acrylate compound (A) is preferably 80% by mass or more, and preferably 90% by mass or more, based on the total mass of the electron beam curable composition. More preferably, it is 95% by mass or more.

In this specification, the (meth)acrylate compound (A) is a compound having one or more (meth)acryloyl groups (sometimes referred to as functional groups) that are polymerizable groups in one molecule. “(Meth)acrylate” refers to both “acrylate” and “methacrylate”. In the electron beam curable composition, the (meth)acrylate compound (A) contains at least a propylene oxide-modified (meth)acrylate (A1) having 3 or more functional groups.

The above (meth)acrylate compound (A) includes a polyfunctional (meth)acrylate monomer other than propylene oxide-modified (meth)acrylate (A1) having a functional group number of 3 or more, a monofunctional (meth)acrylate monomer, a (meth)acrylate oligomer, and (meth)acrylate polymer. In the present invention, the term "monomer" refers to a compound that is the minimum structural unit for constituting an oligomer or polymer, and may be referred to as (meth)acrylate in the following description. Hereinafter, the (meth)acrylate compound constituting the electron beam curable composition will be explained in more detail.

The (meth)acrylate compound (A) constituting the electron beam curable composition contains at least a PO-modified (meth)acrylate (A1) having 3 or more functional groups. Since PO-modified (meth)acrylate has a low surface tension, it suppresses repellency during coating and contributes to improving gloss. From the viewpoint of suppressing repellency and easily obtaining a coating film with excellent gloss, the content of PO-modified (meth)acrylate (A1) having 3 or more functional groups is based on the total mass of the electron beam curable composition. It is preferably 15% by mass or more. The content is more preferably 18% by mass or more, even more preferably 24% by mass or more, and even more preferably 35% by mass or more. On the other hand, in one embodiment, the content of the PO-modified (meth)acrylate (A1) having 3 or more functional groups is preferably 97% by mass or less, based on the total mass of the electron beam curable composition, and 85% by mass or less, based on the total mass of the electron beam curable composition. It is more preferably at most 70% by mass, even more preferably at most 70% by mass.

The PO-modified (meth)acrylate (A1) having 3 or more functional groups preferably has 3 to 6 (meth)acrylate functional groups. The number of functional groups is more preferably 3 or 4, and even more preferably 4.
Specific examples of PO-modified (meth)acrylate (A1) having a functional group number of 3 or more include PO-modified trimethylolpropane tri(meth)acrylate, PO-modified glyceryl tri(meth)acrylate, PO-modified pentaerythritol tri(meth)acrylate, PO Modified isocyanuric acid tri(meth)acrylate, PO modified pentaerythritol tetra(meth)acrylate, PO modified ditrimethylolpropane tetra(meth)acrylate, PO modified dipentaerythritol penta(meth)acrylate, and PO modified dipentaerythritol hexa(meth)acrylate. ) acrylates. These can be used alone or in combination of two or more.

The PO-modified (meth)acrylate (A1) having 3 or more functional groups may have 2 to 20 propylene oxide groups. The number of propylene oxide groups added is preferably 3 to 15, more preferably 3 to 10, and even more preferably 4 to 6.
For example, the PO-modified trimethylolpropane tri(meth)acrylate compound may be PO (3 moles) modified trimethylolpropane tri(meth)acrylate, PO (6 moles) modified trimethylolpropane tri(meth)acrylate. PO-modified glyceryl tri(meth)acrylate compounds include PO (3 mol) modified glyceryl tri(meth)acrylate, PO (6 mol) modified glyceryl tri(meth)acrylate, and PO (9 mol) modified glyceryl tri(meth)acrylate. It's good. The PO-modified isocyanuric acid tri(meth)acrylate compound may be PO (3 moles)-modified isocyanuric acid tri(meth)acrylate. PO-modified pentaerythritol tetra(meth)acrylate compounds include PO (4 mol) modified pentaerythritol tetra(meth)acrylate, PO (8 mol) modified pentaerythritol tetra(meth)acrylate, PO (10 mol) modified pentaerythritol tetra( It may be a meth)acrylate. The PO-modified ditrimethylolpropane tetra(meth)acrylate compound may be a PO-modified (4 mole) ditrimethylolpropane tetra(meth)acrylate. Furthermore, the PO-modified dipentaerythritol hexa(meth)acrylate compound may be a PO-modified (6 mole) dipentaerythritol hexa(meth)acrylate.

In one embodiment, the PO-modified (meth)acrylate (A1) having 3 or more functional groups is PO-modified trimethylolpropane triacrylate, PO-modified pentaerythritol tetra(meth)acrylate, PO-modified ditrimethylolpropane tetra(meth)acrylate, and PO-modified dipentaerythritol hexa(meth)acrylate. Among these, from the viewpoint of curability and gloss, it is preferable to use PO-modified trimethylolpropane triacrylate or PO-modified pentaerythritol tetra(meth)acrylate.

PO-modified (meth)acrylate (A1) having three or more functional groups is available as a commercial product. For example, "ATM-4P" (PO (4 mol) modified pentaerythritol tetraacrylate) and "A-DPA-6PA" (PO (6 mol) modified dipentaerythritol hexaacrylate) manufactured by Shin Nakamura Chemical Industry Co., Ltd. are preferably used. can be used.

In one embodiment, the (meth)acrylate compounds constituting the electron beam curable composition include PO-modified (meth)acrylate (A1) having 3 or more functional groups and other polyfunctional (meth)acrylates having 3 or more functional groups. acrylate monomers.
As a specific example of a (meth)acrylate monomer having three or more functional groups,
Trimethylolpropane tri(meth)acrylate, ε-caprolactone modified tris-(2-acryloxyethyl)isocyanurate, ethoxylated isocyanuric acid tri(meth)acrylate, tris(2-hydroxyethyl)isocyanurate tri(meth)acrylate, and trifunctional (meth)acrylates such as pentaerythritol tri(meth)acrylate,
Tetrafunctional (meth)acrylates such as pentaerythritol tetra(meth)acrylate and ditrimethylolpropane tetra(meth)acrylate,
Examples include pentafunctional (meth)acrylates such as dipentaerythritol penta(meth)acrylate, and hexafunctional (meth)acrylates such as dipentaerythritol hexa(meth)acrylate.

In one embodiment, the polyfunctional (meth)acrylate used in combination with the PO-modified (meth)acrylate (A1) having a functional group number of 3 or more is an alkylene oxide-modified (meth)acrylate having a functional group number of 3 or more (however, a PO-modified (excluding (meth)acrylate). The alkylene oxide-modified (meth)acrylate having 3 or more functional groups may have 2 to 20 alkylene oxide groups and 3 to 6 (meth)acrylate functional groups.

Specific examples of alkylene oxide-modified (meth)acrylates having three or more functional groups include alkylene oxide-modified glyceryl tri(meth)acrylate, alkylene oxide-modified trimethylolpropane tri(meth)acrylate, and alkylene oxide-modified pentaerythritol tri(meth)acrylate. , alkylene oxide-modified trifunctional (meth)acrylates such as alkylene oxide-modified isocyanuric acid tri(meth)acrylates,
alkylene oxide-modified tetrafunctional (meth)acrylates, such as alkylene oxide-modified pentaerythritol tetra(meth)acrylate, and alkylene oxide-modified ditrimethylolpropane tetra(meth)acrylate;
Alkylene oxide modified pentafunctional (meth)acrylates such as alkylene oxide modified dipentaerythritol penta(meth)acrylate, and alkylene oxide modified hexafunctional (meth)acrylates such as alkylene oxide modified dipentaerythritol hexa(meth)acrylate. can be mentioned.

In the above-mentioned (meth)acrylates illustrated, the alkylene oxide group may be at least one selected from the group consisting of ethylene oxide group, butylene oxide group, pentylene oxide group, and hexylene oxide group. Among these, an ethylene oxide group is preferred from the viewpoint of easy availability and suppression of migration. Therefore, in one embodiment, among alkylene oxide-modified (meth)acrylates having three or more functional groups, ethylene oxide (EO)-modified (meth)acrylates having three or more functional groups can be preferably used.

In one embodiment, the (meth)acrylate compound constituting the electron beam curable composition includes a PO-modified (meth)acrylate (A1) having 3 or more functional groups and an EO-modified (meth)acrylate having 3 or more functional groups. It is preferable to include.
Specific examples of EO-modified (meth)acrylates having 3 or more functional groups include EO-modified trimethylolpropane triacrylate, EO-modified glyceryl triacrylate, EO-modified pentaerythritol tri(meth)acrylate, EO-modified pentaerythritol tetra(meth)acrylate, Examples include EO-modified ditrimethylolpropane tetra(meth)acrylate, EO-modified dipentaerythritol penta(meth)acrylate, and EO-modified dipentaerythritol hexa(meth)acrylate. These can be used alone or in combination of two or more.

In one embodiment, among the alkylene oxide-modified (meth)acrylates having three or more functional groups, alkylene oxide-modified trimethylolpropane triacrylate represented by the following general formula (I) can be preferably used.

In general formula (I), R represents an alkylene oxide group. The alkylene oxide group may be one or more groups selected from the group consisting of ethylene oxide, butylene oxide, pentylene oxide, and hexylene oxide. Preferably, R is ethylene oxide.
l+m+n represents the average number of alkylene oxide groups added. The average number of alkylene oxides added is preferably 2 to 20 moles per molecule.

The coating film properties of alkylene oxide-modified trimethylolpropane triacrylate can be easily adjusted by adjusting the type and number of alkylene oxide groups added. For example, by increasing the number of additions, migration due to penetration can be easily suppressed. Furthermore, since it has three reactive acryloyl groups in one molecule, it has high reactivity and can form a strong coating film. By adjusting the content and modification number of the alkylene oxide-modified trimethylolpropane triacrylate compound, a good balance between the strength of the cured coating film and migration suppression can be obtained. Among the alkylene oxide-modified trimethylolpropane triacrylates, EO-modified trimethylolpropane triacrylate can be preferably used.

Commercially available EO-modified trimethylolpropane triacrylates include EO (3 moles) modified trimethylolpropane tri(meth)acrylate, EO (6 moles) modified trimethylolpropane tri(meth)acrylate, and EO (9 moles). Examples include modified trimethylolpropane tri(meth)acrylate, EO (15 mol) modified trimethylolpropane tri(meth)acrylate, and EO (20 mol) modified trimethylolpropane tri(meth)acrylate.

In another embodiment, the (meth)acrylate compound constituting the electron beam curable composition includes a PO-modified (meth)acrylate (A1) having 3 or more functional groups, a (meth)acrylate oligomer, or a (meth)acrylate polymer. It may also include. (Meth)acrylate oligomer or (meth)acrylate polymer means an oligomer or polymer derived from a monomer having at least a (meth)acryloyl group in the molecule. In the present invention, an "oligomer" is a polymer having a relatively low degree of polymerization and having structural units based on 2 to 100 monomers. Since (meth)acrylate oligomers have a higher molecular weight than (meth)acrylate monomers, the risk of migration can be greatly reduced.

In one embodiment, the (meth)acrylate compound preferably contains a PO-modified (meth)acrylate (A1) having three or more functional groups and a (meth)acrylate oligomer. Examples of the (meth)acrylate oligomer include urethane (meth)acrylate, polyester (meth)acrylate, and epoxy (meth)acrylate. The oligomers may be used alone or in combination of two or more. In one embodiment, polyester (meth)acrylate can be suitably used.

Polyester (meth)acrylate may be a compound obtained by polycondensing a polybasic acid and a polyhydric alcohol by a known method, and the molecular weight, hydroxyl group, carboxyl group, etc. The amount of end groups can be adjusted. For example, when the amount of carboxyl groups contained in the polybasic acid is greater than the amount of hydroxyl groups contained in the polyhydric alcohol, the terminal functional group becomes a carboxyl group. By subjecting this carboxyl group to a condensation reaction with the hydroxyl group of the hydroxyl group-containing (meth)acrylate, the desired polyester (meth)acrylate can be obtained.

When polyester (meth)acrylate is used, a strong cured film can be easily obtained. In addition, it has good compatibility with PO-modified (meth)acrylate (A1) having a functional group number of 3 or more, and has a low viscosity, so it is easy to increase the viscosity when using the electron beam curable composition as an ink or varnish. It can be suppressed. In one embodiment, the content of polyester (meth)acrylate in the electron beam curable composition is preferably 25 to 85% by mass, and preferably 45 to 65% by mass, based on the total mass of the composition. is more preferable.

Polyester (meth)acrylates can also be obtained as commercial products. Examples include EBECRYL820, 824, 837, and 450 manufactured by Daicel Allnex, and these can be preferably used.

In one embodiment, the (meth)acrylate compound constituting the electron beam curable composition is optionally at least one selected from the group consisting of monofunctional (meth)acrylate monomers and bifunctional (meth)acrylate monomers. It may further contain seeds.
Specific examples of monofunctional (meth)acrylate monomers include 2-ethylhexyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, β-carboxylethyl (meth)acrylate, and 4-tert. -Butylcyclohexynol (meth)acrylate, tetrahydrofurfuryl acrylate, alkoxylated tetrahydrofurfuryl acrylate, caprolactone (meth)acrylate, lauryl (meth)acrylate, stearyl (meth)acrylate, isoamyl (meth)acrylate, phenoxyethyl (meth)acrylate Acrylate, isodecyl (meth)acrylate, 3,3,5-trimethylcyclohexanol (meth)acrylate, cyclohexyl (meth)acrylate, isobornyl (meth)acrylate, norbornyl (meth)acrylate, dicyclopentanyl (meth)acrylate, Cyclopentenyl (oxyethyl) (meth)acrylate, 1,4-cyclohexanedimethanol (meth)acrylate, cyclic trimethylolpropane formal (meth)acrylate, benzyl (meth)acrylate, EO-modified nonylphenol acrylate, 2-methyl-2- Examples include ethyl-1,3-dioxolan-4-yl)methyl acrylate and acryloylmorpholine.

Specific examples of difunctional (meth)acrylate monomers include 1,3-butylene glycol di(meth)acrylate, 1,4-butanediol di(meth)acrylate, and 3-methyl-1,5-pentanediol di(meth)acrylate. Acrylate, 1,6-hexanediol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, 1,10-decanediol di(meth)acrylate, 1,2-dodecanediol di(meth)acrylate, Neopentyl glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, hydroxypivalic acid neopentyl glycol di(meth)acrylate, dipropylene glycol di(meth)acrylate, tripropylene glycol di(meth)acrylate (meth)acrylate, EO-modified 1,6-hexanediol di(meth)acrylate, PO-modified neopentyl glycol di(meth)acrylate, (neopentyl glycol-modified) trimethylolpropane di(meth)acrylate, dimethylol tricyclode Kandi(meth)acrylate, EO-modified bisphenol A di(meth)acrylate, PO-modified bisphenol A di(meth)acrylate, cyclohexanedimethanol di(meth)acrylate, dimethylol-tricyclodecane di(meth)acrylate, and dicyclopenta Examples include nyldi(meth)acrylate.

As mentioned above, the electron beam curable composition improves repellency during coating by containing 15% by mass or more of PO-modified (meth)acrylate (A1) having 3 or more functional groups based on the total mass of the composition. It is possible to easily obtain a coating film that suppresses generation and has excellent gloss. In one embodiment, the content of the PO-modified (meth)acrylate (A1) having 3 or more functional groups may be 100% by mass based on the total mass of the (meth)acrylate compound (A). In such an embodiment, the content of the PO-modified (meth)acrylate (A1) having 3 or more functional groups is preferably 80% by mass or more, and 90% by mass or more based on the total mass of the electron beam curable composition. It is more preferably at least 95% by mass, and even more preferably at least 95% by mass.

Furthermore, by using the PO-modified (meth)acrylate (A1) having three or more functional groups in combination with another (meth)acrylate compound, it becomes easy to improve migration and coating film properties. For example, when PO-modified (meth)acrylate (A1) with a functional group number of 3 or more and an EO-modified (meth)acrylate with a functional group number of 3 or more are used together, migration, repellency, and gloss can be improved in a well-balanced manner. . In such an embodiment, the total amount of the PO-modified (meth)acrylate (A1) having 3 or more functional groups and the EO-modified (meth)acrylate having 3 or more functional groups, based on the total mass of the (meth)acrylate compound. may be 100% by mass. In the above embodiment, the content of the PO-modified (meth)acrylate (A1) having 3 or more functional groups may preferably be in the range of 15 to 70% by mass based on the total mass of the electron beam curable composition. , more preferably in the range of 24 to 65% by weight, and still more preferably in the range of 40 to 60% by weight.

PO-modified or EO-modified (meth)acrylates having three or more functional groups are available as commercial products, and each manufacturer specifies the number of PO or EO additions. However, in reality, there is a distribution in the number of additions, and only the main number of additions is clearly specified, and there are variations in molecular weight. Therefore, in order to understand the net number of additions, it is necessary to measure the molecular weight distribution by GPC (gel permeation chromatography) or the like.

From this point of view, in the present invention, the molecular weight distribution of each (meth)acrylate compound constituting the electron beam curable composition is measured by GPC, and the content of the compound having a molecular weight in a specific range is determined from the graph. do. For example, in the GPC graph, if the component amount in the molecular weight range of less than 500 is The content of is calculated as A×X (%). Since oligomers and polymers also have molecular weight distributions, molecular weights are generally defined as weight average molecular weights or number average molecular weights. However, in the present invention, the content of the compound is calculated from the content of the compound having a molecular weight in a specific range obtained from the GPC graph as described above.

Among the (meth)acrylate compounds constituting the electron beam curable composition, a (meth)acrylate compound having a molecular weight of less than 500 has good curability and can form a strong coating film. However, since the molecular weight is low, migration due to penetration of unreacted components is likely to occur. Therefore, in the electron beam curable composition, it is preferable to reduce the content of (meth)acrylate compounds having a molecular weight of less than 500 as much as possible. Therefore, in one embodiment, from the viewpoint of suppressing migration, the content of the (meth)acrylate compound having a molecular weight of less than 500 is preferably less than 25% by mass based on the total mass of the composition. It is preferable that the (meth)acrylate compound contains two or more types of (meth)acrylate compounds. For example, the (meth)acrylate compound may include a PO-modified (meth)acrylate having three or more functional groups and an EO-modified (meth)acrylate or polyester (meth)acrylate having three or more functional groups. In this case, it is preferable that the content of components having a molecular weight of less than 500 in each compound is less than 25% by mass.

As mentioned above, when the content of components having a molecular weight of less than 500 is less than 25% by mass, the level of migration can be easily suppressed within an acceptable range. The content of the (meth)acrylate compound having a molecular weight of less than 500 in the (meth)acrylate compound is more preferably less than 21% by mass, and even more preferably less than 16% by mass, based on the total mass of the composition. It's fine. In one embodiment, the content may be 0% by mass.

From the viewpoint of suppressing migration, the (meth)acrylate compound preferably contains one or more (meth)acrylate compounds having a molecular weight of 500 or more. In one embodiment, it may include a PO-modified (meth)acrylate having three or more functional groups and an EO-modified (meth)acrylate or polyester (meth)acrylate having three or more functional groups, each having a molecular weight of 500 or more. is preferred.

In one embodiment, the viscosity of the electron beam curable composition is preferably less than 700 mPa·s. When the viscosity is less than 700 mPa·s, it becomes easy to suppress a decrease in leveling properties and to obtain excellent gloss as a coating film property. However, even if the viscosity is 700 mPa·s or more, a cured coating film with excellent gloss can be obtained by using a printing device equipped with heating equipment. The viscosity is preferably less than 600 mPa·s, more preferably less than 500 mPa·s, and even more preferably less than 400 mPa·s. This viscosity refers to a value measured according to JIS Z8803:2011, and is a value measured using an E-type viscometer at 25°C. When PO-modified (meth)acrylate (A1) having 3 or more functional groups is used in combination with other (meth)acrylate compounds as the (meth)acrylate compound constituting the electron beam curable composition, the viscosity can be easily adjusted. can do. Therefore, for example, an electron beam curable composition having a viscosity of less than 700 mPa·s can be easily obtained.

(Resin beads (B))
In one embodiment, the electron beam curable composition may further include resin beads (B). The use of resin beads can improve the slip properties of the coating film. The resin beads may be in the form of particles made of various resins or particles whose surfaces are coated with various resins. The resin serving as the raw material may be, for example, at least one selected from the group consisting of silicone resin, acrylic resin, polyethylene resin, polypropylene resin, amide resin, polytetrafluoroethylene resin, and urethane resin. Although not particularly limited, when polytetrafluoroethylene (PTFE) beads are used, slip properties can be easily improved.
Resin beads can be obtained as commercial products. For example, the Tosle Pearl series (silicone beads) manufactured by Momentive Co., Ltd. and the Art Pearl series (acrylic beads) manufactured by Negami Kogyo Co., Ltd. can be suitably used.

The content of the resin beads may be less than 5.0% by mass based on the total mass of the electron beam curable composition. In one embodiment, the content of the resin beads may be preferably 4.5% by mass or less, more preferably 4.2% by mass or less, still more preferably 4.0% by mass or less. It's fine. By adjusting the content of resin beads to less than 5.0% by mass, reduction in glossiness can be easily suppressed. In one embodiment, the content of resin beads may be 0% by mass.
In one embodiment, from the viewpoint of slip properties and gloss, the content of resin beads may preferably be 0.15 to 3.5% by mass. The content may be more preferably 0.25 to 3.0% by mass, still more preferably 0.5 to 2.0% by mass, even more preferably 0.5 to 1.5% by mass. It may be mass %.

In one embodiment, from the viewpoint of glossiness, the average particle diameter of the resin beads may be preferably 0.5 to 6.0 μm, more preferably 0.5 to 5.0 μm, and still more preferably It may be 0.7 to 4.0 μm. In one embodiment, from the viewpoint of slip properties, the average particle diameter of the resin beads may be preferably 1.3 to 6.0 μm, more preferably 1.5 to 5.0 μm, and even more preferably may be 2.0 to 4.0 μm. When the average particle diameter of the resin beads is adjusted within the above range, the cured coating film has a good balance between slip properties and gloss. The above average particle size is a value obtained by measuring the particle size (volume basis) where the integrated value corresponds to 50% in the particle size distribution curve using a laser diffraction particle size distribution analyzer SALD-2200 manufactured by Shimadzu Corporation. be.

(Leveling agent)
In one embodiment, the electron beam curable composition may further include a leveling agent. By using a leveling agent, leveling properties are improved, and coating film properties such as repellency, pinhole properties, and gloss can be easily improved. The leveling agent that can be used is not particularly limited, and may be a known compound. Although not particularly limited, in one embodiment, an acrylic leveling agent can be suitably used. Generally, when a leveling agent that significantly reduces the surface tension of a cured coating film is used, the ink printed on the cured coating film becomes more repellent, resulting in a decrease in printing suitability. On the other hand, when an acrylic leveling agent is used, an overprint ink can be applied to the cured coating film to easily print an expiration date or a bar code. In this way, when an acrylic leveling agent is used, it is easy to obtain better optical properties without reducing printing suitability.

As the acrylic leveling agent, known compounds having a poly(meth)acrylate skeleton can be used. The carboxyl group in the side chain of the poly(meth)acrylate skeleton may be esterified, such as an alkyl ester, or may form an organic salt such as an amine salt. Acrylic leveling agents are also available as commercial products. Specific examples include BYK series acrylic leveling agents manufactured by BYK Chemie Japan Co., Ltd., such as BYK-350, BYK-352, BYK-354, BYK-355/356, BYK-358N/361N, BYK-381. , BYK-392, BYK-394, BYK-3440, and BYK-3441. Although not particularly limited, BYK-361N can be suitably used.

(synthetic amorphous silica)
In one embodiment, the electron beam curable composition may further include synthetic amorphous silica. Synthetic amorphous silica is broadly classified into wet process silica and dry process silica, but it may be either of them. The wet process silica may be either precipitation (precipitation) process silica or gel process silica. These silicas can generally be synthesized by a neutralization reaction between sodium silicate and a mineral acid (usually sulfuric acid).
On the other hand, dry process silica uses silicon tetrachloride as a raw material and is obtained by hydrolyzing it in a flame of oxygen and hydrogen. Hydrophilic silanol groups and hydrophobic siloxane are present on the surface of the obtained silica. Silanol groups are chemically active and can undergo chemical reactions with other substances. For example, hydrophilic silica can be made hydrophobic by reacting a silanol group with an organic treatment agent. In addition, various functions can be imparted to silica depending on the type of functional group (surface modification group) of the treatment agent. Main surface modification groups include dimethylsilyl group, trimethylsilyl group, octylsilyl group, alkylsilyl group, dimethylpolysiloxane group, aminoalkylsilyl group, methacrylsilyl group, and the like.

Although not particularly limited, dry process silica is preferred from the viewpoint of gloss and transparency. Furthermore, from the viewpoint of compatibility and dispersion stability, silica whose surface has been modified with a treatment agent containing a dimethylsilyl group is preferred. In one embodiment, the synthetic amorphous silica may have the same composition as the resin beads, but can be differentiated by true specific gravity and specific surface area in terms of required functionality. For example, it is preferable that the synthetic amorphous silica has a true specific gravity of 1.60 or more at 25° C. and a specific surface area of 50 m ² /g or more by the BET method.
In one embodiment, the specific surface area of the synthetic amorphous silica determined by the BET method may be preferably 50 to 380 m ² /g, more preferably 70 to 330 m ² /g, and even more preferably 90 to 230 m ² /g. It may be. Furthermore, the average primary particle diameter of the synthetic amorphous silica may be preferably 7 to 40 nm, more preferably 10 to 35 nm, and even more preferably 12 to 30 nm. Such synthetic amorphous silica can also be obtained as a commercial item. For example, AEROSIL R972 manufactured by Nippon Aerosil Co., Ltd. (average primary particle diameter 16 nm, specific surface area 110 m ² /g, dry method silica) can be suitably used.

(Polymerization inhibitor)
The electron beam curable composition that is one embodiment of the present invention may further contain a polymerization inhibitor to improve storage stability. Specific examples of polymerization inhibitors include (alkyl)phenol, hydroquinone, catechol, resorcinol, p-methoxyphenol, t-butylcatechol, t-butylhydroquinone, pyrogallol, 1,1-picrylhydrazyl, phenothiazine, and p-benzoquinone. , nitrosobenzene, 2,5-di-tert-butyl-p-benzoquinone, dithiobenzoyl disulfide, picric acid, cuperone, aluminum N-nitrosophenylhydroxylamine, tri-p-nitrophenylmethyl, N-(3-oxyanilino- Examples include 1,3-dimethylbutylidene)aniline oxide, dibutylcresol, cyclohexanoneoximcresol, guaiacol, o-isopropylphenol, butyraldoxime, methylethylketoxime, and cyclohexanoneoxime. If a polymerization inhibitor is used, its content may range from 0.01 to 1% by weight, based on the total weight of the composition.

(Other ingredients)
The electron beam curable composition that is an embodiment of the present invention may further contain components known in the art, such as an inert resin, as necessary. In one embodiment, the electron beam curable composition may further contain known additives, if necessary. As additives, for example, curing agents, plasticizers, wetting agents, adhesion aids, antifoaming agents, antistatic agents, trapping agents, antiblocking agents, silica particles, preservatives, etc. can be used. Additionally, oils, flame retardants, fillers, stabilizers, reinforcing agents, matting agents, abrasives, etc. may be used.

In order to constitute the electron beam curable composition of the above embodiment, biomass-derived raw materials using renewable resources such as plants can be preferably used as various raw materials from the viewpoint of carbon neutrality.

The electron beam curable composition of the above embodiment does not substantially contain a photopolymerization initiator. Here, "substantially not containing" means that it is not intentionally added to the composition and that the content due to unintentional addition is less than 1%. Unintentional addition includes cases where the substance is contained in trace amounts in each raw material, contamination during the composition manufacturing process, and the printed matter manufacturing process. Since the electron beam curable composition does not substantially contain a photopolymerization initiator, it is possible to solve the problem of migration of the photopolymerization initiator or its decomposed product that occurs when a photopolymerization initiator is used.

<Method for producing electron beam curable composition>
As a method for producing the electron beam curable composition of the present invention, the (meth)acrylate compound (A) and resin beads, a leveling agent, a polymerization inhibitor, etc. used as necessary are mixed using a mixer or the like. It can be produced by mixing and stirring for about 30 minutes to 3 hours. In addition, two or more types of (meth)acrylate compounds (A) are mixed and stirred in advance, and then resin beads (B), a leveling agent, synthetic amorphous silica, a polymerization inhibitor, etc. are further added. You may.

<Printing method>
The method for printing the electron beam curable composition of the above embodiment is not particularly limited, and any known method can be used. Specific examples include a roll coater, rod coater, blade, wire bar, doctor knife, spin coater, screen coater, gravure coater, offset gravure coater, and flexo coater. In addition, in-line printing and offline printing, UV curing type, electron beam curing type, heat drying type, evaporation drying type, oxidation polymerization type, penetrating drying type, thermal polymerization type, two-component curing type, liquid toner type, and powder It is also possible to use a combination of toner-type inks and the like as necessary.

In one embodiment, the coating amount of the composition after electron beam curing is preferably 0.5 to 10 g/m ² , more preferably 1.0 to 5.0 g/m ² . After the printed layer is formed by the above printing method, the printed layer is immediately passed through an electron beam irradiation machine to form an electron beam cured printed layer. Note that the irradiation dose of the electron beam may be 10 to 150 kGy at an accelerating voltage of 110 kV. In one embodiment, the electron beam irradiation can be carried out at an irradiation dose of 15 to 100 kGy, preferably at an accelerating voltage of 110 kV, more preferably from 20 to 45 kGy at an accelerating voltage of 110 kV. After irradiation with the electron beam, heating may be performed as necessary to accelerate curing.

<Electron beam curing overcoat varnish>
The electron beam curable composition of the above embodiment can be suitably used as an electron beam curable overcoat varnish. Electron beam-curable overcoat varnish is applied to the printed and non-printed surfaces of the substrate, and is irradiated with electron beams to form a cured coating film that is used to coat the printed and non-printed surfaces of the substrate. This is an electron beam curable composition intended to provide surface properties.

Electron beam curable compositions used as overcoat varnishes often do not contain pigments, dyes, or other coloring components. The surface properties required for overcoat varnish applications vary depending on the final use of the printed material. For example, the purpose of gloss coat varnish is basically to protect the surface and provide gloss. In addition, overcoat varnish has matte properties, slip properties, non-slip properties, soft feel properties, heat resistance, solvent resistance, pseudo adhesion, printing suitability, piercing properties, repellency, peelability, barrier properties, etc. Sometimes required. The electron beam curable composition that is an embodiment of the present invention has excellent properties such as gloss required for gloss coat varnish. Further, the electron beam curable composition of the above embodiment can exhibit slip properties in addition to gloss.

There are two methods for applying electron beam-curable overcoat varnish: a wet method, in which the overcoat varnish is immediately applied before the first printing surface dries, and the other is the wet method, in which the overcoat varnish is applied immediately after the first printing surface dries. It can be divided into a dry method in which a coat varnish is applied, and either method may be used. In one embodiment, the electron beam curable composition can be suitably used as an overcoat varnish used for forming a surface layer of a food packaging material.

<Food packaging materials>
One embodiment of the present invention relates to a food packaging material that includes a base material and a surface layer provided on the base material, the surface layer being a cured layer of the electron beam curable composition of the above embodiment.
(Base material)
The base material is preferably a film-like base material. In one embodiment, for example, a polyolefin base material such as polyethylene or polypropylene, a polyester base material such as polyethylene terephthalate or polylactic acid, a polycarbonate base material, a polystyrene base material such as polystyrene, AS resin, or ABS resin, a nylon base material, or a polyamide base material. Examples include a base material such as a polyvinyl chloride base material, a polyvinylidene chloride base material, a cellophane base material, a paper base material, an aluminum base material, or a film-like base material made of a composite material thereof.
Alternatively, a vapor deposition base material in which an inorganic compound such as silica, alumina, or aluminum is vapor-deposited onto a film base material can also be used. Further, the vapor-deposited surface may be coated with polyvinyl alcohol or the like. The surface of the base material to be printed (the surface in contact with the printing layer) is preferably treated to facilitate adhesion. Specific examples of the adhesion-facilitating treatment include corona discharge treatment, ultraviolet/ozone treatment, plasma treatment, oxygen plasma treatment, primer treatment, and the like. Furthermore, if sufficient adhesion cannot be obtained with the polyethylene terephthalate base material, surface treatments such as acrylic coating treatment, polyester treatment, and polyvinylidene chloride treatment may be performed.

A paper base material may be used as the base material. The paper base material may be ordinary paper or cardboard, and the film thickness is not particularly specified. The thickness of the paper base material may be, for example, 0.2 mm to 1.0 mm and 20 to 150 g/m ² , and the printing surface may be treated to facilitate adhesion. The surface of the paper base material may be vapor-deposited with a metal such as aluminum for the purpose of imparting design properties. Further, the paper base material may be surface-coated with acrylic resin, urethane resin, polyester resin, polyolefin resin, or other resin, and may also be subjected to surface treatment such as corona treatment. . For example, specific examples of surface-treated paper base materials include coated paper and art paper.

The above-described base material (first base material) can also be used in a structure in which a second base material is further laminated on the surface opposite to the surface to be printed. In this case, the second base material to be laminated may be the same as the film-like base material described above. The second base material may be the same as or different from the first base material. Among these, as the second base material, unstretched polyethylene, unstretched polypropylene, nylon base material, aluminum foil base material, aluminum vapor-deposited base material, etc. are preferable. In this case, the second base material is preferably bonded to the first base material using an adhesive layer.

Examples of the adhesive layer include a layer made of an anchor coating agent, a urethane laminating adhesive, a molten resin, and the like. Examples of anchor coating agents (AC agents) include imine-based AC agents, isocyanate-based AC agents, polybutadiene-based AC agents, and titanium-based AC agents. Examples of urethane-based laminate adhesives include polyether urethane-based laminate adhesives and polyester-based laminate adhesives. Examples include laminating adhesives. These adhesives include those containing organic solvents and those without solvents. Furthermore, examples of the molten resin include molten polyethylene.

(barrier property)
In one embodiment, the second base material can also be provided with barrier properties against gases (oxygen, water vapor, nitrogen, carbon dioxide, etc.). Methods for imparting barrier properties include a method of introducing a barrier substrate as a laminate and a method of forming a barrier layer by coating. Barrier materials that can be introduced include silica, alumina, aluminum, vinylidene chloride-methyl acrylate copolymer, ethylene-vinyl alcohol copolymer, polyvinylidene chloride, polyvinyl alcohol, polyvinyl alcohol-vinyl acetate copolymer, metaxylylene. Examples include adipamide, MXD6 nylon, and the like. Furthermore, a coextruded film that is a combination of the above-mentioned barrier material and a base material can also be used. On the other hand, unlike this technique, active packaging, which is a type of technique that actively removes oxygen that enters the inside of the container, can also be applied. Active barrier materials used in active packaging include materials in which resins are blended with substances that react with oxygen, such as reduced iron/sodium chloride, sodium sulfite, and ascorbic acid. In addition, cobalt salts such as MXD6 nylon/cobalt salt, double bond polymer/cobalt salt, and cyclohexene side chain-containing polymer/cobalt salt are blended into the resin as an oxidation catalyst, and this acid value catalyst oxidizes the resin to release oxygen. Examples include absorbent materials.

(Surface layer)
The surface layer is composed of a cured coating film of the electron beam curable composition of the above embodiment. It can be formed by applying an electron beam curable composition onto a base material and curing it by irradiating it with an electron beam. The amount of the electron beam curable composition to be applied to obtain a cured coating film is not particularly limited, but it is preferably adjusted in consideration of the average particle size of the resin beads in the electron beam curable composition.
In one embodiment, it is preferable to adjust the ratio (b/t) between the average particle diameter b of the resin beads (B) in the cured coating film and the coating amount t. If the ratio (b/t) is too small, high gloss/low slip properties tend to occur; if it is too large, low gloss/high slip properties tend to occur.
In one embodiment, the ratio (b/t) is preferably 0.5 to 2.0, more preferably 0.6 to 1.5, and more preferably 0.8 to 1.2. is even more preferable. When the ratio (b/t) is adjusted to fall within the above range, it becomes easy to achieve both slip properties and gloss.

(Production method)
One embodiment of the present invention relates to a method of manufacturing food packaging materials. The above manufacturing method includes applying an electron beam curable composition on a base material to form a coating film, and curing the coating film with an electron beam to form a surface layer consisting of a cured coating film. . In forming the surface layer, the ratio (b/t) of the average particle diameter b of the resin beads (B) in the cured coating film to the coating amount t of the electron beam curable composition is 0.5 to 2.0. The method includes applying the electron beam curable composition of the above embodiment so that the composition becomes as follows. According to such an embodiment, it is possible to provide a food packaging material that has excellent slip properties in addition to improved migration, repellency, and gloss.

EXAMPLES Hereinafter, the present invention will be specifically described as examples, but the present invention is not limited to the following examples. In the present invention, "parts" and "%" respectively represent "parts by mass" and "% by mass" unless otherwise specified.

(Raw materials used)
Details of each raw material listed in Tables 1 and 2 are as follows.
<(meth)acrylate compound (A)>
A-TMPT-6PO: Manufactured by Shin Nakamura Chemical Co., Ltd., TMP(PO)6TA (PO (6 mol) modified trimethylolpropane triacrylate)
Miramer M3190: manufactured by MIWON, TMP (EO) 9TA (EO (9 mol) modified trimethylolpropane triacrylate)
OTA-480: manufactured by Daicel Allnex, Gly(PO)3TA (PO (3 mol) modified glyceryl triacrylate)
EBECRYL50: manufactured by Daicel Allnex, PETTA (EO) 5 (EO (5 mol) modified pentaerythritol tetraacrylate)
ATM-4P: Manufactured by Shin Nakamura Chemical Industry Co., Ltd., PETTA (PO) 4 (PO (4 mol) modified pentaerythritol tetraacrylate)
EBECRYL1142: Manufactured by Daicel Allnex, DiTMPTA (ditrimethylolpropane tetraacrylate)
AD-TMP-4P: Manufactured by Shin Nakamura Chemical Industry Co., Ltd., DiTMPTA (PO) 4 (PO (4 mol) modified ditrimethylolpropane tetraacrylate)
Miramer M600: manufactured by MIWON, DPHA (dipentaerythritol hexaacrylate)
A-DPH-6PA: Shin Nakamura Chemical Industry Co., Ltd., DPHA (PO) 6 (PO (6 mol) modified dipentaerythritol hexaacrylate)
EBECRYL820: Manufactured by Daicel Allnex, polyester acrylate

TPGDA: Manufactured by Daicel Allnex, TPGDA (tripropylene glycol diacrylate)
Miramer M300: manufactured by MIWON, TMPTA (trimethylpropane triacrylate)
Miramer M3130: manufactured by MIWON, TMP(EO)3TA (EO (3 mol) modified trimethylolpropane triacrylate)
Etermer 2381: manufactured by Choko Materials Co., Ltd., TMP(PO)3TA (PO (3 mol) modified trimethylolpropane triacrylate)
Miramer M3160: manufactured by MIWON, TMP(EO)6TA (EO (6 mol) modified trimethylolpropane triacrylate)

<Resin beads (B)>
X-52-85: Manufactured by Shin-Etsu Chemical Co., Ltd., average particle size 0.7 μm, silicone beads SST-1 MG-RC: Manufactured by Shamrock Co., Ltd., average particle size 1.0 μm, PTEF beads Art Pearl J3PY: Manufactured by Negami Kogyo Co., Ltd. , average particle size 1.2 μm, acrylic beads Tospearl 120: manufactured by Momentive Co., Ltd., average particle size 2.0 μm, silicone beads Art Pearl J4PY: manufactured by Negami Kogyo Co., Ltd., average particle size 2.2 μm, acrylic beads Tospearl 130: manufactured by Momentive Co., Ltd. , average particle size 2.7 μm, silicone beads SST 3H-RC: manufactured by Shamrock, average particle size 4.0 μm, PTEF beads Tospearl 240 ^* : manufactured by Momentive, average particle size 4.0 μm, silicone beads Ceraflore991: BYK Chemie manufactured by Momentive, average particle size 5.0 μm, polyethylene beads Tospear 2000B: manufactured by Momentive, average particle size 6.0 μm, silicone beads

<Leveling agent (C)>
BYK-361N: Manufactured by BYK Chemie, acrylic leveling agent <synthetic amorphous silica (D)>
AEROSIL R972: Nippon Aerosil Co., Ltd., average primary particle diameter 16 nm, specific surface area 110 m ² /g, dry process silica)
<Polymerization inhibitor (E)>
Genorad24: manufactured by LAHN, di-t-butyl-7-phenylquinone methide

(molecular weight distribution)
The molecular weight distribution of the compound used as the (meth)acrylate component (A) in the following Examples and Comparative Examples was measured using gel permeation chromatography (HLC-8320) manufactured by Tosoh Corporation. A calibration curve was created using standard polystyrene samples. Tetrahydrofuran was used as the eluent, and three TSK gel Super HM-M (manufactured by Tosoh Corporation) were used as the columns. The measurement was performed under conditions of a flow rate of 0.6 ml/min, an injection volume of 10 μl, and a column temperature of 40°C.
Based on the graph of the gel permeation chromatography (GPC) measurement conducted under the above conditions, the proportion of each area in which the molecular weight was less than 500 was determined, and the weight average molecular weight was also measured. These results are shown in Tables 1 and 2 as the percentage (%) of (I) molecular weight less than 500.

<1> Preparation of electron beam curable composition (Example 1)
78.3 parts of A-TMPT-6PO (propane oxide modified trimethylolpropane triacrylate) manufactured by Shin Nakamura Chemical Industries, Ltd., and ATM-4P ((PO (4 mol) modified pentaerythritol tetraacrylate) manufactured by Shin Nakamura Chemical 18.0 parts of CREATE), 1.0 part of silicone beads with an average particle diameter of 2.0 μm (Tospearl 120 manufactured by Momentive), 0.5 parts of an acrylic leveling agent (BTY-361N manufactured by BIC Chemie), Example 1 was prepared by mixing 2.0 parts of synthetic amorphous silica (AEROSIL R972 manufactured by Nippon Aerosil Co., Ltd.) and 0.2 parts of a polymerization inhibitor (Genorad 24 manufactured by LAHN) and stirring using a butterfly mixer. An electron beam curable composition was prepared.

(Examples 2 to 34)
Electron beam curable compositions of Examples 2 to 34 were prepared in the same manner as in Example 1, except that the materials and ratios listed in Table 1 were used.

(Comparative Examples 1 to 17)
Electron beam curable compositions of Comparative Examples 1 to 17 were prepared in the same manner as in Example 1, except that the materials and ratios listed in Table 2 were used.

<2> Evaluation of electron beam curable overcoat varnish Printed matter was produced using each of the electron beam curable compositions prepared in Examples 1 to 34 and Comparative Examples 1 to 17, and the electron beam curable overcoat varnish was It was evaluated as follows.

<2-1> Method for producing printed matter (method for producing printed matter in Example 1)
Using the electron beam curable composition obtained in Example 1, printing was performed on a substrate by a flexographic printing method. A cured coating was formed by immediately irradiating the printed coating with an electron beam to produce a printed matter (a substrate with a cured coating on the surface). More details are as follows.
In the above printing, Flexiproof 100 manufactured by RK was used as a printing machine. The printing conditions were a printing speed of 70 m/min, an anilox roll line number of 100 to 500 lines/inch, and an anilox roll cell capacity of 8 to 20 cm ³ /m ² . The engraving pattern on the anilox roll was hexagonal. A Flexcel NXH digital flexo plate manufactured by Kodak was used as the printing plate, and the area of the printing plate was 157.5 cm ² .
The coating amount of the electron beam curable composition was printed so that the coating amount after curing was 2 to 3 g/m ² .
The electron beam irradiation was performed using an electron beam irradiation machine EC250/15/180L manufactured by Iwasaki Electric Co., Ltd. under conditions of an acceleration voltage of 110 kV and an electron beam dose of 30 kGy.
As the base material, a laminate of a biaxially stretched polypropylene film and an unstretched polypropylene film was used. An electron beam curable composition was printed on the biaxially stretched polypropylene film side of the laminate. The laminate was produced as follows. (Method for producing laminate laminate)
A diluted adhesive solution was applied to a biaxially stretched polypropylene film manufactured by Innovia Film (product name: RGN-30, thickness 30 μm), and the solvent was evaporated. An adhesive diluted solution was prepared by diluting an adhesive (TM-321A/TM-321B=2/1, manufactured by Toyo Morton Co., Ltd.) with ethyl acetate so that the active ingredient content was 30%. The diluted adhesive solution was applied at room temperature using a bar coater, with the amount of solid content applied after solvent volatilization adjusted to 2.0 to 2.5 g/m ² .
Next, the surface of the film coated with the diluted adhesive was bonded to an unstretched polypropylene film (manufactured by Futamura Chemical Co., Ltd., FHK2, 30 μm). Next, it was left to stand for 24 hours in an environment of 35° C. and humidity of 60% RT to 80% RT to obtain a laminate.

(Method for producing printed matter of Examples 2 to 34)
In the same manner as the printed matter of Example 1, printed matter was produced using the electron beam curable compositions obtained in Examples 2 to 34, respectively.

(Method for producing printed matter of Comparative Examples 1 to 17)
In the same manner as the printed matter of Example 1, printed matter was produced using the electron beam curable compositions obtained in Comparative Examples 1 to 17, respectively.

<2-2> Various evaluations Using the printed matter obtained above, various evaluations were performed according to the following. The evaluation results are shown in Table 1.
(Migration resistance evaluation)
Migration was evaluated for printed matter produced using the electron beam curable compositions of Examples and Comparative Examples according to the method described below.
First, three sheets of 9cm x 9cm were cut out from the printed matter, and the three sheets were stacked so that the printed and non-printed surfaces were in contact with each other, and the sheets were heated at 25°C under a 50% environmental condition under a load of 1kg/ ^dm2 . It was kept for 10 days under the condition. Thereafter, the central printed matter among the three was taken out and set in a migration cell so that 50 ml of 95% ethanol came into contact with the area of 0.5 dm ² of its non-printed surface.
Thereafter, residual monomers were extracted at 60° C. for 10 days while stirring. The migration cell is completely sealed by a device, and loss of the contents and contamination of the contents (extract) with other components can be completely suppressed in the above steps. Next, the above extract was analyzed using a quadrupole-time-of-flight mass spectrometer manufactured by Bruker Daltonics and an LC30A series liquid chromatograph manufactured by Shimadzu Corporation. Furthermore, the migration resistance of the (meth)acrylate compound (A) present in ethanol was evaluated according to the evaluation criteria based on the detected concentration described below.
The evaluation criteria are as follows.
Pass: The amount of migration is 50 ppb or less for all components in the composition.
Fail: The amount of migration exceeds 50 ppb for one or more components in the composition.

(Playing evaluation)
Images of repellency on the surfaces of printed matter produced using the electron beam curable compositions of Examples and Comparative Examples were observed using a laser microscope (product name "VK-X100" manufactured by Keyence Corporation). Next, image processing was performed using an application (observation application "VX-H1XV"), and the area of the flicked area on the film was calculated. The repellency was evaluated based on the area ratio of the repellent area to the surface of the printed matter.
The evaluation criteria are as follows.
Pass: The area ratio of the repelled area to the surface of the printed matter is less than 5%.
Fail: The area ratio of the repelled area to the surface of the printed matter is 5% or more.

(Evaluation of glossiness)
The gloss values (JISZ 8741 ) was measured. The gloss of the printed matter was evaluated based on the gloss value according to the following criteria. It should be noted that printed matter that failed the evaluation of playability was not evaluated and was written as "NA". Ratings of 3 to 5 are within the industrially practical range.
(Evaluation criteria)
5: Gloss value is 125 or more 4: Gloss value is 120 or more and less than 125 3: Gloss value is 115 or more and less than 120 2: Gloss value is 110 or more and less than 115 1: Gloss value is less than 110 be

(Resin bead average particle diameter/coating amount ratio)
The average particle diameter of the resin beads represents the volume-based average particle diameter (D50) measured by the Coulter counter method using a product named "Multicizer" manufactured by Beckman Coulter.
The coating amount (g/m ² ) of the electron beam curable composition is a value calculated by dividing the weight (g) of the cured coating film by the coating area (m ² ). Since the specific gravity of the electron beam curable compositions (varnishes) prepared in Examples and Comparative Examples is approximately 1.0, the coating amount and coating film thickness are approximately equal. Therefore, in the present invention, instead of the ratio of resin bead average particle diameter/coating film thickness, the ratio of resin bead average particle diameter/coating amount was calculated. The results are shown in Tables 1 and 2.
Generally, if the average particle diameter of the resin beads is too small than the coating film thickness, the particles will be hidden within the coating film, making it difficult to develop slip properties. On the other hand, if the average particle diameter of the resin beads is too large than the coating thickness, the glossiness will be greatly reduced. From this point of view, in one embodiment of the present invention, the ratio (b/t) of the average particle diameter b of the resin beads (B) in the cured coating film to the coating amount t is 0.5 to 2.0. It is preferably from 0.6 to 1.5, even more preferably from 0.8 to 1.2.

(Slip property)
For the printed matter obtained using the electron beam curable compositions of Examples and Comparative Examples, the coefficient of dynamic friction between coating films was determined according to JIS K7125 (Plastic films and sheets - Friction coefficient test method). Ta.
From the obtained values, slip properties were evaluated according to the following criteria. The results are shown in the table. It should be noted that printed matter that failed the evaluation of playability was not evaluated and was written as "NA".
5: Dynamic friction coefficient is less than 0.45.
4: Dynamic friction coefficient is 0.45 or more and less than 0.55.
3: Dynamic friction coefficient is 0.55 or more and less than 0.65.
2: Dynamic friction coefficient is 0.65 or more and less than 0.75.
1: Dynamic friction coefficient is 0.75 or more.

As described above, it can be seen that the electron beam curable composition (Example), which is an embodiment of the present invention, can realize excellent migration resistance. In addition, by adjusting the type and amount of the (meth)acrylate compound that makes up the electron beam curable composition, it is possible to suppress the occurrence of repellency and obtain good results in terms of coating properties such as gloss. I understand that. Therefore, by using the electron beam curable composition that is an embodiment of the present invention, it is possible to suppress external migration of unreacted components remaining in the cured coating film and provide printed matter with excellent repellency and gloss. becomes possible. Further, according to one embodiment, the printed surface (coated film surface) has excellent slip properties, so that it is possible to efficiently proceed with the filling and conveying process of contents when using the food packaging material.

Claims (12)

Contains one or more (meth)acrylate compounds (A) containing propylene oxide (PO) modified (meth)acrylate (A1) having a functional group number of 3 or more, satisfies the following (1) and (2), and initiates photopolymerization. An electron beam curable composition that is substantially free of agents .
(1) In each of the one or more (meth)acrylate compounds (A), the content of the (meth)acrylate compound having a molecular weight of less than 500 is less than 25% by mass based on the total mass of the composition.
(2) The content of the propylene oxide (PO) modified (meth)acrylate (A1) having three or more functional groups is 15% by mass or more based on the total mass of the composition. Furthermore, it contains resin beads (B) having an average particle diameter of 0.5 to 6.0 μm, and the content of the resin beads (B) is 5.0 μm based on the total mass of the electron beam curable composition. The electron beam curable composition according to claim 1, which is less than % by mass. The propylene oxide (PO)-modified (meth)acrylate (A1) having a functional group number of 3 or more is PO-modified trimethylolpropane triacrylate, PO-modified glyceryl triacrylate, PO-modified pentaerythritol tetra(meth)acrylate, PO-modified ditrimethylolpropane. The electron beam according to claim 1 or 2, comprising at least one selected from the group consisting of tetra(meth)acrylate, PO-modified dipentaerythritol penta(meth)acrylate, and PO-modified dipentaerythritol hexa(meth)acrylate. Curable composition. The electron beam curable composition according to any one of claims 1 to 3, wherein the (meth)acrylate compound (A) further contains an ethylene oxide (EO) modified (meth)acrylate having a functional group number of 3 or more. . The electron beam curable composition according to any one of claims 1 to 4, further comprising an acrylic leveling agent. The electron beam curable composition according to any one of claims 1 to 5, further comprising synthetic amorphous silica. The electron beam curable composition according to any one of claims 1 to 6, which has a viscosity at 25° C. of 700 mPa·s or less. The electron beam curable composition according to any one of claims 1 to 7 , which is used as an electron beam curable overcoat varnish. The electron beam curable composition according to claim 8 , which is used for forming a surface layer of a food packaging material. A food packaging material comprising a base material and a surface layer provided on the base material, the surface layer comprising a cured coating film of the electron beam curable composition according to any one of claims 1 to 9 . The surface layer consists of a cured coating film of the electron beam curable composition according to any one of claims 2 to 9 , comprising one or more (meth)acrylate compounds (A) and resin beads (B). A food packaging material,
The ratio (b/t) of the average particle diameter b of the resin beads (B) in the cured coating film to the coating amount t of the electron beam curable composition forming the cured coating film is 0.5 to 2. 11. The food packaging material according to claim 10 , wherein the food packaging material is .0. The electron beam curable composition according to any one of claims 2 to 9 , which contains one or more (meth)acrylate compounds (A) and resin beads (B), is applied onto a base material. Forming a film includes curing the coating film with an electron beam to form a surface layer consisting of a cured coating film,
In forming the surface layer, the ratio (b/t) of the average particle diameter b of the resin beads (B) in the cured coating film and the coating amount t of the electron beam curable composition forming the cured coating film. is 0.5 to 2.0, a method for producing a food packaging material.