JP6793485B2 - Photocurable resin composition - Google Patents

Description

The present invention is a resin composition that is applied to an opaque envelope or the like, cured by active energy rays such as ultraviolet rays, and partially or entirely translucently processed so that the underlying printed matter or pattern can be seen through. In particular, the present invention relates to a photocurable resin composition having excellent permeability and less bleeding even when the drying time is long after application to paper.

As a technique for impregnating paper with resin to make it translucent, there is a method of impregnating paper with light-ultraviolet curable ink to make the paper transparent (Patent Document 1). Further, as a composition to be impregnated in the paper, a solvent-free composition containing an ultraviolet polymerization type composition containing a polymerizable vinyl oligomer and a photopolymerizable vinyl monomer and an oxidation polymerization type composition has been proposed (patented). Document 2). However, this formulation is not a fast-curing type, and contains an oxidizing component that does not cure with ultraviolet rays, and the curing progresses gradually, so there are problems such as changes in transparency over time, stains on printed matter during printing, and blocking when loaded after printing. there were.

As a fast-curing composition that can deal with these problems, a photopolymerizable vinyl oligomer and a photopolymerizable vinyl monomer are contained, and the paper surface temperature after varnish application is 100 ° C to 160 ° C when irradiated with far infrared rays for 1 to 3 seconds. Then, a method for producing a transparent processed paper to be irradiated with ultraviolet rays has been proposed (Patent Document 3). If this method is used, problems caused by the curing speed can be solved, but in terms of equipment, a far-infrared irradiation device that raises the paper surface temperature in a short time is required, and in terms of manufacturing conditions, the paper surface temperature is 100 ° C or higher. In some cases, it could not be implemented because there were many restrictions such as the need to raise it to.

Japanese Patent Application Laid-Open No. 61-41397 Patent No. 3282019 Patent No. 3676731

An object of the present invention is a resin composition that is applied to an opaque envelope or the like, cured by active energy rays such as ultraviolet rays, and partially or the entire surface of the paper is translucently processed so that the underlying printed matter or pattern can be seen through. Therefore, it is an object of the present invention to provide a photocurable resin composition having excellent permeability and less bleeding, particularly even when the drying time is long after application to paper.

The invention according to claim 1 is a resin composition for transparent processed paper obtained by permeating it into an absorbent paper and then curing it with active energy rays, and comprises a polyfunctional acrylic-modified oligomer (A) and (A). ), A polyfunctional acrylic monomer (B) other than the above, and a photopolymerization initiator (C). The (A) is a bifunctional EO-modified bisphenol A type diacrylate, and the viscosity of the composition at 25 ° C. , 500 mPa · s and less than 3,000 mPa · s.

The invention according to claim 2 provides the photocurable resin composition according to claim 1, further comprising an acrylic group-containing polyester-modified polydimethylsiloxane .

In the invention according to claim 3, the blending amount of the above (A) with respect to the total solid component is 75% by weight to 90% by weight, and the above (B) is 5% by weight to 10% by weight with respect to the total composition. The photocurable resin composition according to any one of claims 1 or 2 is provided.

The photocurable resin composition of the present invention is applied to an opaque envelope or the like and cured by active energy rays such as ultraviolet rays to make a part or the entire surface of the paper translucent so that the underlying printed matter or pattern can be seen through. It is useful as a fast-curing photocurable resin composition that is processed, has excellent permeability to paper, and has little bleeding after application.

The composition of the composition of the present invention is a polyfunctional acrylic modified oligomer (A), a polyfunctional acrylic monomer (B) other than (A), and a photopolymerization initiator (C). In addition, in this specification, (meth) acrylate includes both acrylate and methacrylate.

The polyfunctional acrylic modified oligomer (A) used in the present invention is a main component having a (meth) acrylate structure and reacting with (B) to form a transparent resin cured film, for example, a bisphenol skeleton or a novolak phenol skeleton. There are epoxy acrylates having an aliphatic skeleton, urethane acrylates having an aliphatic skeleton or an aromatic skeleton, polyester acrylates, polybutadiene acrylates, acrylic acrylates, bisphenol type acrylates, etc., which can be used alone or in combination of two or more. The number of functional groups is preferably 2 to 3 functional from the viewpoint of curing shrinkage.

Of these, bisphenol-type acrylates and polyester acrylates having relatively low viscosities are preferable. In particular, ethylene oxide-modified (hereinafter referred to as "EO-modified") bisphenol A diacrylate is particularly preferable because it has a high curing rate. The molecular weight is preferably 400 to 3,000, more preferably 480 to 2,000. When the molecular weight is 400 or more, it becomes easy to adjust the viscosity appropriately, and when it is 3,000 or less, it becomes easy to control the curing rate. The blending amount of (A) with respect to the total solid composition is preferably 75% by weight to 95% by weight, more preferably 80% by weight to 90% by weight. When it is 75% by weight or more, a viscosity suitable for workability can be secured, and when it is 95% by weight or less, impregnation into paper becomes easy.

The polyfunctional acrylic monomer (B) other than (A) used in the present invention is a main component that reacts with (A) to form a transparent resin cured film, promotes permeability to paper, and at the same time. It also plays a role in adjusting the viscosity of the composition. Since it may be dried in a drying oven after being applied to paper, it is preferably low in volatility from the viewpoint of safety, and the molecular weight is preferably 600 or less. Further, it is preferable that it does not contain a siloxane bond in terms of permeability to paper.

Examples of the bifunctional (meth) acrylate include triethylene glycol diacrylate, neopentyl glycol diacrylate, 3-methyl-1.5 pentadiol diacrylate, and 1.4-butanediol di (meth) acrylate, 4.6. -Hexanediol di (meth) acrylate, 1.9-nonanediol di (meth) acrylate, neopentyl glycol dimethacrylate, 1.10-decanediol diacrylate, ethylene glycol dimethacrylate, polyethylene glycol diacrylate, diethylene glycol dimethacrylate, There are 2-hydroxy-3-acryloyloxypropyl methacrylate, and as trifunctional (meth) acrylates, for example, trimethyl propanetri (meth) acrylate, ethylene oxide-modified trimethylol propanetri (meth) acrylate, propylene oxide-modified trimethylol propane. Tri (meth) acrylate, tris (2-acryloxyethyl) isocyanurate, ε-caprolactone-modified tris (2-acryloxyethyl) isocyanurate, pentaerythritol tri (meth) acrylate, dipentaerythritol tri (meth) acrylate, alkyl There are modified dipentaerythritol tri (meth) acrylates.

Further, examples of the tetrafunctional or higher functional (meth) acrylate include trimethylolpropane tetra (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol tetra (meth) acrylate, and alkyl-modified dipentaerythritol tetra (meth). There are acrylate, dipentaerythritol penta (meth) acrylate, alkyl-modified dipentaerythritol penta (meth) acrylate, dipentaerythritol hexa (meth) acrylate, caprolactone-modified dipentaerythritol hexa (meth) acrylate, etc., alone or in combination of two or more. Can be used in combination.

Among these, polyethylene glycol diacrylate (# 300), trimethylolpropane triacrylate, tripropylene glycol diacrylate, dipentaerythritol hexaacrylate and the like having a molecular weight of 600 or less are suitable. The blending amount of (B) with respect to the total solid composition is preferably 5% by weight to 10% by weight. If it is less than 5% by weight, the impregnation property of the paper is lowered and the transparency becomes difficult to stabilize, and if it exceeds 10% by weight, the amount of volatilization in the drying process becomes remarkable, and after UV curing, it is partially called "white blur". Whitening phenomenon is likely to occur.

The photopolymerization initiator (C) used in the present invention generates radicals by irradiation with ultraviolet rays, electron beams, or the like, and the radicals trigger a polymerization reaction, and a general-purpose photopolymerization initiator may be used. Specifically, 2-hirodoxy-1- {4- [4- (2-hydroxy-2-methyl-propionyl) -benzyl] phenyl} -2-methyl-propan-1-one, 1-hydroxy-cyclohexyl-phenyl -Ketone, bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide, 2-hydroxy-2-methyl-1-phenyl-propane-1-one, 1- [4- (2-hydroxyethoxy)- There are phenyl] -2-hydroxy-2-methyl-1-propane-1-one and the like, and they can be used alone or in combination of two or more. It is preferably blended in an amount of 1 to 10 parts by weight, more preferably 4% by weight to 8% by weight, based on 100 parts by weight of the radically polymerizable component.

The pressure-sensitive adhesive composition of the present invention contains, if necessary, a reactive diluent and leveling agent, a defoaming agent, a wetting agent, an antiblocking agent, an antioxidant, a flame retardant, a polymerization inhibitor, etc., as long as the performance is not impaired. Various additives may be included.

Examples of the leveling agent include acrylic type, vinyl type, and silicone type, but a silicone type having a siloxane bond in the molecule having a high surface tension lowering ability is preferable. By adding the leveling agent, the film thickness after application to the paper becomes uniform, and as a result, the amount of penetration into the paper can be made uniform, so that the transparency after UV curing is stabilized. The blending amount with respect to the total solid composition is preferably 0.05% by weight to 3% by weight, and as commercially available leveling agents, BYK-UV3500, BYK-UV3510 and BYK-UV3570 (trade name: BYK-Chemie, acrylic group). Contains polyester-modified polydimethylsiloxane) and the like.

The viscosity of the photocurable resin composition of the present invention is larger than 500 mPa · s at 25 ° C. and is 3,000 mPa · s or less, and is particularly preferably 600 mPa · s to 1,500 mPa · s. At 500 mPa · s or less, if the drying time after applying the resin composition is long, the viscosity becomes low, the permeability to the substrate becomes too good, and bleeding easily occurs, or conversely, the volatilization amount of the monomer increases. The amount of permeation becomes uneven, and the transparency and appearance become unstable. Further, if it exceeds 3,000 mPa · s, the permeability to the base material decreases, and it becomes difficult to obtain stable transparency.

As a coating method for applying the resin composition of the present invention to a substrate such as paper, known coating methods such as gravure printing, flexographic printing, screen printing, roll coating, bar coating, and blade coating may be used, and the coating amount may be paper. It may be arbitrary depending on the type of paper, but in general, in order for the paper to have sufficient transparency, a wet thickness of about 30 μm to 50 μm is a guideline.

After the application of the resin composition, it is preferable to lower the viscosity by raising the temperature in a drying oven to promote the penetration of the resin into the substrate. Specific examples of the drying conditions include a drying time of about 60 seconds in a warm air drying furnace having a set temperature of 80 ° C. to 100 ° C. Under these conditions, no special equipment such as a far-infrared irradiation device is required, and the temperature of the paper surface is 100 ° C or less, so there is no problem in terms of safety, and a transparent appearance can be obtained stably. Can be done.

When the resin composition of the present invention is cured by ultraviolet rays, a known light source such as a high-pressure mercury lamp, a metal halide lamp, a xenon lamp, or an electrodeless discharge lamp is used, and an integrated light amount of, for example, 50 to 1,000 mJ / cm ² is irradiated. And cure.

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but specific examples are shown, and the present invention is not particularly limited thereto. Unless otherwise specified, the measurement was performed under the conditions of room temperature of 25 ° C. and relative humidity of 65%. Further, Example 4 and Example 8 are described as reference examples.

Example 1
New Frontier BPE-4 (trade name: Daiichi Kogyo Seiyaku Co., Ltd., bifunctional EO-modified bisphenol A type diacrylate) as (A), PE-300 (trade name: Daiichi Kogyo Seiyaku Co., Ltd.) as (B), PEG # 300 diacrylate), Irgacure 907 and 184 (trade name: manufactured by BASF Japan) as (C), and BYK-UV3570 (trade name: manufactured by BYK-Chemie) as a leveling agent, as shown in Table 1. In the formulation, the resin composition of Example 1 was prepared by placing it in a light-shielding bottle and stirring and defoaming it until it was uniformly dissolved.

Examples 2-9
In addition to the materials used in Example 1, New Frontier BPE-20 (trade name: manufactured by Daiichi Kogyo Seiyaku Co., Ltd., bifunctional EO-modified bisphenol A type diacrylate) and PE-44F (trade name: BASF Japan) are used as (A). TMPTA (trade name: trimethylolpropane triacrylate) and DPHA (commodity) using LR8800 (trade name: BASF Japan, trifunctional polyester acrylate) as (B). Name: Dipentaerythritol hexaacrylate manufactured by Nippon Kayaku Co., Ltd.) and TPGDA (trade name: Tripropylene glycol diacrylate manufactured by BASF Japan Co., Ltd.) are used and uniformly dissolved in a light-shielding bottle according to the formulation shown in Table 1. Each resin composition of Examples 2 to 9 was prepared by stirring and defoaming.

Comparative Examples 1 to 4
In addition to the materials used in Examples 1 to 9, ACMO (trade name: KJ Chemicals, acryloyl morpholine) and HOP-A (trade name: Kyoei Kagaku, 2-hydroxypropyl acrylate) were used as monofunctional acrylate monomers. Each resin composition of Comparative Examples 1 to 4 was prepared by placing in a light-shielding bottle and stirring and defoaming until the mixture was uniformly dissolved.

Table 1

The evaluation method was as follows.

Measurement sample A resin composition is applied to an area of 55 mm × 100 mm of envelope paper (60 to 70 g / m2 of paper density) using a # 22 bar coater, and dried in a thermostat at 100 ° C. for 1 minute. After that, using an electrodeless UV irradiation device F300S / LC-6B manufactured by Fusion UV Systems Japan, the H valve was cured by ultraviolet irradiation so that the output was 1,300 mW / cm2 and the integrated light amount was 50 mJ / cm2.

Viscosity: Using a cone plate type viscometer RC-550 manufactured by Toki Sangyo, measured at a cone angle of 3 ° R17.65 at 25 ± 1 ° C and a rotation speed of 10 rpm, and measured over 500 mPa · s and below 3000 mPa · s. Others were marked with x.

Total light transmittance: Based on JISK7361-1, measured using a haze guard manufactured by Toyo Seiki Seisakusho, and the evaluation was evaluated as ◯ for 75% or more and x for the others.

Turbidity: According to JIS K 7136, the measurement was performed using a haze guard manufactured by Toyo Seiki Seisakusho, and the evaluation was evaluated as ◯ for 91% or less and x for the others.

Bleeding: At the time of preparing the measurement sample, the distance of bleeding from the edge of the area coated with the bar coater was measured, and the bleeding amount of less than 5 mm was marked with ◯, and 5 mm or more was marked with x.

The evaluation results are shown in Table 2.
Table 2

The photocurable resin compositions of Examples were all good in each evaluation result.

On the other hand, Comparative Example 1 in which the blending amount of (A) was small had a large bleeding, Comparative Examples 2 and 3 in which a monofunctional acrylic monomer was blended had a large bleeding, and Comparative Examples 1 and 3 had a low viscosity. Further, Comparative Example 4 in which the photocurable monomer was not blended had a high viscosity, and the total light transmittance and the turbidity were also evaluated as ×, neither of which was suitable for the present invention.

The present invention is a photocurable resin composition that is applied to an opaque envelope or the like, cured by active energy rays such as ultraviolet rays, and partially or the entire surface of the paper is translucently processed so that the printed matter or pattern underneath can be seen through. It is useful as a thing.

Claims (3)

A resin composition for transparent processed paper obtained by permeating it into absorbent paper and then curing it with active energy rays. It is a polyfunctional acrylic-modified oligomer (A) and a polyfunctional acrylic monomer other than (A). B) and a photopolymerization initiator (C) are contained, and the (A) is a bifunctional EO-modified bisphenol A type diacrylate, and the viscosity of the composition at 25 ° C. is larger than 500 mPa · s and 3 A photocurable resin composition of 000 mPa · s or less. The photocurable resin composition according to claim 1, further comprising an acrylic group-containing polyester-modified polydimethylsiloxane . The invention according to claim 1 or 2 , wherein the blending amount of the (A) with respect to the total solid components is 75% by weight to 90% by weight, and the (B) is 5% by weight to 10% by weight with respect to the total composition. Photocurable resin composition.