JPH1149985A - Activated energy ray hardening coating agent for released document sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an activated energy ray hardening coating agent for released document sheet which shows no adherence at ordinary temperatures and under an atmospheric pressure but can form a coating layer giving releasable pseudo-adherence by pressing when the coating agent is coated on a sheet substrate and hardened by irradiation of activated energy ray. SOLUTION: An activated energy ray hardening coating agent contains 15-70 weight% of base polymer (A) and 30-85 weight% of a reactive diluent (B) and further contains 0-10 weight% of an additive (C) and 0-20 weight% of a light polymerization initiator (D) based on the total weight of the base polymer (A) and the diluent (B). In this case the base polymer (A) is a (meth)acrylate- based copolymer obtained by polymerizing 20-80 weight% of (meth)acrylate having an alkyl group of 8-22 carbon atoms (a1) and 20-80 weight% of an α,β-unsaturated monomer (a2) copolymerizable with (a1).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an active energy ray-curable coating agent applied to a release form sheet used for a postcard or the like.

[0002]

2. Description of the Related Art In recent years, in order to automate the notification work and reduce the mailing cost, a mail using a bonded postcard in which a notification portion of a postcard is concealed has been provided instead of a sealed postcard. In order to conceal the contents of the notification, the laminated postcard can be folded in two or three or the like and folded and temporarily adhered (pseudo-adhered) by pressure, but can be easily A release form sheet capable of peeling off the contact surface and opening the concealed contents is used. As such a release form sheet,
Since the surface finish is good, a film in which a pseudo-adhesion layer is provided on the surface of a printed material applied to a sheet substrate with an adhesive is widely used.

[0003] However, the above-mentioned exfoliated form sheet is disadvantageous in that the cost is high, and since the film is bonded to the sheet base material, it is difficult to regenerate the paper when paper is used as the sheet base material. . To compensate for this drawback, there has been proposed a method in which a coating material comprising a UV-curable resin and an appropriate amount of a pressure-sensitive adhesive is directly applied to a sheet substrate (Japanese Patent Application Laid-Open No. 8-188724).
Although it exhibits pseudo-adhesion, it has the disadvantage that it adheres to the sheet substrate when it is stacked or wound up, since it has adhesiveness even after irradiation with ultraviolet light. In addition, there is a drawback that the adhesive is sticky even when peeled off after pseudo-adhesion, so that it adheres to other postcards or the like.

[0004]

SUMMARY OF THE INVENTION The present invention is intended to provide a sheet-like base material which has no tackiness under normal conditions of normal temperature and normal pressure when cured by irradiating with active energy rays. It is an object of the present invention to provide an active energy ray-curable coating agent for a release form sheet that can form a coating layer that can be pseudo-adhered releasably.

[0005]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to solve the above-mentioned problems, and as a result, the following specific (meth) acrylate-based copolymer has been used as a base polymer. The present inventors have found that the above object can be achieved by using an active energy ray-curable coating agent, and have completed the present invention.

That is, the present invention relates to (A) base polymer 15
-70% by weight and (B) 30-85% by weight of a reactive diluent, and furthermore (C) no additives based on the total weight of (A) the base polymer and (B) the reactive diluent.
-10% by weight and (D) 0-20% by weight of photopolymerization initiator
An active energy ray-curable coating agent comprising: (A1) 20 to 80% by weight of (a1) a (meth) acrylic acid ester having an alkyl group having 8 to 22 carbon atoms and (A1) a2) Peeling characterized by comprising a (meth) acrylate-based copolymer obtained by copolymerizing 20 to 80% by weight of an α, β-unsaturated monomer copolymerizable with (a1). The present invention relates to an active energy ray-curable coating agent for a form sheet.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION As described above, the (A) base polymer of the active energy ray-curable coating agent of the present invention comprises (a1) a (meth) acrylic acid ester having an alkyl group having 8 to 22 carbon atoms and (A) a2) A (meth) acrylate-based copolymer obtained by copolymerizing an α, β-unsaturated monomer copolymerizable with (a1). still,
(Meth) acrylate means methacrylate and / or acrylate, and (meth) in the present invention has the same meaning.

Examples of the (a1) (meth) acrylate having an alkyl group having 8 to 22 carbon atoms include octyl (meth) acrylate, decyl (meth) acrylate, lauryl (meth) acrylate, and ( Examples include stearyl (meth) acrylate and behenyl (meth) acrylate. Among these (a1) components, stearyl methacrylate is preferred. These (a1) components can be used alone or in combination of two or more. The alkyl group of the component (a1) includes a branched alkyl group in addition to a linear alkyl group. For example, the octyl group includes 2-ethylhexyl and the like.

(A2) As the α, β-unsaturated monomer copolymerizable with the component (a1), for example, styrene,
Styrenes such as α-methylstyrene and vinyltoluene; methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, hexyl (meth) acrylate, (meth) Cyclohexyl acrylate, allyl (meth) acrylate,
(Meth) acrylic acid esters having an alkyl group having 1 to 7 carbon atoms, such as benzyl (meth) acrylate;
Dimethylaminoethyl acrylate, dimethylaminomethyl (meth) acrylate, dimethylaminoethyl (meth)
Nitrogen-containing (meth) acryloyl compounds such as acrylamide, diethylaminoethyl (meth) acrylamide, and acryloylmorpholine; and nitrogen-containing α, β-unsaturated monomers such as N-vinylformamide; in addition, vinyl acetate and (meth) acrylonitrile , Divinylbenzene, maleic acid diester and the like. These (a2)
The components can be used alone or in combination of two or more. In order to enhance the curability of the coating agent of the present invention, it is preferable to include a nitrogen-containing α, β-unsaturated monomer in the component (a2). The type of the component (a2) is determined in consideration of the adhesiveness, curability, appropriate viscosity and the like of the coating agent of the present invention.

The amounts of the components (a1) and (a2) used are 20 to 80% by weight of the component (a1) and 20% by weight of the component (a2).
~ 80% by weight. When the content of the component (a1) is less than 20% by weight, the ratio of the long-chain alkyl group having good releasability is reduced, so that a coating agent is applied.
When a release form sheet irradiated with active energy rays is folded, pressed, and left to stand, blocking occurs, and peeling tends to be impossible. From these points, the component (a1) is preferably at least 30% by weight, and the component (a2) is preferably at least 7% by weight.
It is preferably 0% by weight or less. On the other hand, when the component (a1) exceeds 80% by weight, the glass transition temperature of the base polymer (A) becomes low, so that the adhesiveness of the release form sheet obtained by applying a coating agent and irradiating with active energy rays is reduced. It is expensive, and it will be in close contact only by folding. From these points, the component (a1) is preferably at most 70% by weight,
2) The component is preferably at least 30% by weight. In order to enhance the curability of the coating agent of the present invention, (a2)
The nitrogen-containing α, β-unsaturated monomer used as a component is (a)
5 to 50 based on the total weight of component 1) and component (a2)
% By weight is preferred. That is, when a nitrogen-containing α, β-unsaturated monomer is used as the component (a2), the content of the nitrogen-containing α, β-unsaturated monomer is 5 to 50% by weight (a2).
20-80% by weight of the component is constituted.

The (A) base copolymer (meth) acrylate copolymer can be easily prepared by using the above-mentioned components (a1) and (a2) in predetermined amounts, and subjecting the mixture to radical polymerization. Can be manufactured. The radical polymerization method is not particularly limited, and a known method such as a solution polymerization, a suspension polymerization, or a bulk polymerization method can be appropriately selected, but the solution polymerization method is usually most suitable. In the polymerization, ordinary reaction conditions can be appropriately adopted. For example, when a solution polymerization method is employed, the components may be charged dropwise, charged simultaneously, or dividedly charged, and the polymerization temperature is generally 60 to 14
The reaction time is about 5 ° C. and the reaction time is about 2 to 8 hours. It is sufficient that various known polymerization catalysts and radical polymerization initiators are appropriately selected and used.

The reactive diluent (B) of the present invention is not particularly limited as long as it is a reactive compound having a carbon-carbon double bond. For example, various known diluents such as acrylic oligomers and acrylic monomers can be used. Compounds can be used. Specifically, trimethylolpropane triacrylate,
Trifunctional or more reactive diluents (b) such as (meth) acryloyl compounds such as pentaerythritol triacrylate, ditrimethylolpropane tetraacrylate, dipentaerythritol hexaacrylate, and ethylene oxide-modified trimethylolpropane triacrylate
1), hexanediol diacrylate, nonanediol diacrylate, tripropylene glycol diacrylate, neopentyl glycol diacrylate, bisphenol A tetraethylene glycol diacrylate, (meth) acryloyl compounds such as acryloylmorpholine, N-vinylformamide, etc. And a monofunctional or bifunctional reactive diluent (b2). As these (B) reactive diluents, the release coating sheet obtained by applying the obtained coating agent and irradiating with active energy rays, after pressurization, the adhesive force increases upon standing and is blocked, making it impossible to release. It is preferable to use the component (b1) and the component (b2) in combination so as not to cause the problem. When the component (b1) and the component (b2) are used in combination, the component (b2)
Bifunctional reactive diluents are particularly preferred. The reactive diluent (B) is determined in consideration of the compatibility with the base polymer (A), curability, adhesiveness, appropriate viscosity, and the like, and may be used alone or in an appropriate combination. You can also.

The active energy ray-curable coating agent of the present invention comprises (A) a base polymer comprising the (meth) acrylate-based copolymer and (B) a reactive diluent. Is determined from the coating viscosity of the obtained coating agent and the like. That is, the active energy ray-curable coating agent of the present invention comprises (A) 15 to 70% by weight of the base polymer and (B) 30 to 85% by weight of the reactive diluent. (A) Base polymer is 1
If the content is less than 5% by weight, the good release property of the base polymer (A), that is, the degree of development of the blocking resistance becomes low,
When a coating sheet is coated, and a release form sheet irradiated with active energy rays is folded, left under pressure and left, blocking occurs, and peeling tends to be impossible. From these points, it is preferable that (A) the base polymer is 20% by weight or more, and (B) the reactive diluent component is 80% by weight.
The following is preferred. On the other hand, if the amount of the base polymer (A) exceeds 70% by weight, there is a problem that the obtained coating agent has a high viscosity and the coating workability is reduced, and the glass transition temperature of the cured film is low. And the release form sheet obtained by irradiating with an active energy ray has a high adhesiveness, and is adhered only by folding.
From these points, the base polymer (A) is preferably 65% by weight or less, and the reactive diluent component (B) is preferably 3% by weight or less.
It is preferably at least 5% by weight.

(B) As reactive diluent (b1)
When the component and the component (b2) are used in combination, the amount of each component is about 5 to 40% by weight based on the total weight of the base polymer (A) and the reactive diluent (B). (B2) The component is preferably about 25 to 80% by weight, and the total weight of these components is (B) 30 to 30% by weight of the reactive diluent.
Make up 85% by weight.

The active energy ray-curable coating agent of the present invention can optionally use an additive (C) as an optional component, and the amount of the additive is determined by the amount of the components (A) and (B). 10% by weight or less based on the total weight. Specific examples of the additive (C) include a polymerization inhibitor, a filler, a slip agent, a leveling agent, a thixotropic agent, and an antifoaming agent. Further, the active energy ray-curable coating agent of the present invention usually uses a photopolymerization initiator (D) when it is cured by ultraviolet rays, and is not particularly required when it is cured by an electron beam. As the photopolymerization initiator, various known photopolymerization initiators can be used without any limitation, and the amount of the photopolymerization initiator is 20% by weight or less, preferably 12% by weight, based on the total weight of the components (A) and (B). % Or less. Specific examples of the photopolymerization initiator (D) include Darocure 1173, Irgacure 651, Irgacure 184, and Irgacure 907.
(Registered trademark of Ciba-Geigy), benzophenone,
o-benzoylbenzoic acid methyl ester, p-dimethylaminobenzoic acid ester, p-dimethylacetophenone, thioxanthone, alkylthioxanthone, amylphosphine oxide compound, oligo [2-hydroxy-2-methyl-1--4- (1methyl Vinyl) phenylpropanone] (Ezacure KIP150, manufactured by Lamberti), amines and the like, and can be used alone or in combination as appropriate.

The thus-obtained active energy ray-curable coating agent of the present invention is usually applied to various sheet base materials after printing. The coating method is not particularly limited, for example, a roll coater, a gravure coater, a flexo coater,
Known means such as an offset printing machine and a screen printing machine can be appropriately employed. After the application of the coating agent, curing by irradiation with active energy rays is performed by a usual method to obtain a release form sheet. When irradiating ultraviolet rays as active energy rays, low-pressure or high-pressure mercury lamps, metal halide lamps, xenon lamps,
An electrodeless discharge lamp, a carbon arc lamp, or the like can be used. When irradiating an electron beam, a typical one such as a Cockcroft-Walton type, a Vandegraph type, or a resonance transformer type can be used. The exfoliated form sheet thus obtained is folded in two or three or the like and folded, and the printed information is pseudo-adherently concealed so as to be releasable by pressure, and then sent to the recipient.

[0017]

By using the active energy ray-curable coating agent for a release form sheet of the present invention, a coating layer which has no tackiness in a normal state at normal temperature and normal pressure, but can be pseudo-adhered releasably under pressure. A release form sheet having the same is obtained. The release form sheet thus obtained has a good surface finish, and can be manufactured at a lower cost as compared with a film in which a film is bonded to a sheet substrate. Further, when paper is used as the sheet base material, the paper has a feature that the paper can be recycled.

[0018]

EXAMPLES The present invention will be specifically described below with reference to production examples and examples, but the present invention is not limited to only these examples. In each example, all parts and percentages are by weight unless otherwise specified.

Production Example 1 (Production of (A) Base Polymer) 25 parts of toluene was charged into a reactor equipped with a stirrer, a cooling pipe, a dropping funnel and a nitrogen introducing pipe, and then the stearyl methacrylate was added to the dropping funnel. (Hereinafter referred to as SMA) 50 parts, methyl methacrylate (hereinafter referred to as MMA) 20 parts, dimethylaminoethyl methacrylate (hereinafter referred to as DM) 30 parts, and 2,2'-azobisisobutyronitrile (catalyst) (Hereinafter referred to as AIBN) was charged into the dropping funnel. Next, the mixed solution was added dropwise to the system at 90 ° C. over 4 hours under a nitrogen stream, and the reaction was further continued for 1 hour to complete the polymerization. After completion of the reaction, the temperature was raised to 160 to 170 ° C., and toluene was distilled off under reduced pressure at the same temperature for about 1 hour at 30 mmHg to obtain a target copolymer.

Production Examples 2 to 7 The reaction was carried out in the same manner as in Production Example 1 except that the kind or amount of the monomer used in Production Example 1 was changed as shown in Table 1, to obtain a target copolymer. . In the table, ST means styrene, and EHA means 2-ethylhexyl acrylate.

[0021]

[Table 1]

Example 1 (Preparation of active energy ray-curable coating agent) (A) Copolymer 4 obtained in Production Example 1 as base polymer
0 parts, (B) 40 parts of nonanediol diacrylate (hereinafter referred to as NDDA) as a reactive diluent and ditrimethylolpropanetetraacrylate (hereinafter DTM)
20 parts of PTA), (D) 5 parts of Irgacure 184 (manufactured by Ciba Geigy) as a photopolymerization initiator, and (C) 0.1 part of methquinone as a polymerization inhibitor are weighed in a beaker and heated at 80 ° C. The mixture was stirred and dissolved to prepare an active energy ray-curable coating agent.

Examples 2 to 7 and Comparative Examples 1 to 5 The same procedures as in Example 1 were carried out except that the type or amount of the copolymer or the amount of the reactive diluent used was changed as shown in Table 2. Similarly, an active energy ray-curable coating agent was prepared.

[0024]

[Table 2]

(Preparation of Release Report Sheet) After coating the active energy ray-curable coating agent obtained in Examples or Comparative Examples on a coated paper using a bar coater # 3, a high-pressure mercury air-cooled lamp (120 W / Cm, irradiation distance 1
0 cm) and irradiate ultraviolet rays (belt speed 10 m
/ Min) to obtain a release form sheet. The following performance evaluation was performed on the obtained release form sheet. Table 3 shows the results.

(Adhesion before pressurization) A test substrate obtained by cutting the obtained release form sheet to a width of 10 cm was folded in two so that the coating layer was in contact with each other, and the two were overlaid. Decided.

(Adhesion after pressurization) The test substrate folded in two was pressurized by a table roll press (MSC-29, manufactured by Yuri Roll Machine Co., Ltd.) at a predetermined linear pressure shown below. After that, it was further cut into a width of 2.5 cm and left under the following predetermined conditions. Immediately after pressing, 1 day, 3 days, and 7 days later, the test substrate was peeled off by hand, and the state of the coating layer was visually determined.

Condition A (pressing linear pressure: 100 kg / cm, leaving condition: no load, 25 ° C., 50% RH), condition B (pressing linear pressure: 200 kg / cm, leaving condition: 1 kg load, 3
0 ° C., 65% RH).

[0029]

[Table 3]

In Table 3, "pseudo-adhesion" means that the peeled coating layer is in the same state as before lamination, and "peeling" means that a part of the paper base material has peeled because a part of the coating layer has adhered. This means that non-peelable means that the entire surface of the coating layer is in close contact.

Claims (4)

[Claims] (A) 15 to 70% by weight of a base polymer
And (B) 30 to 85% by weight of a reactive diluent, and (C) 0 to 10% by weight of an additive based on the total weight of (A) the base polymer and (B) the reactive diluent.
And (D) an active energy ray-curable coating agent containing 0 to 20% by weight of a photopolymerization initiator, wherein the (A) base polymer has (a1) an alkyl group having 8 to 22 carbon atoms. (Meth) acrylate 20-
80% by weight and (a2) a (meth) acrylate-based copolymer obtained by copolymerizing 20 to 80% by weight of an α, β-unsaturated monomer copolymerizable with (a1). An active energy ray-curable coating agent for a release form sheet, characterized in that: 2. The active energy ray-curable coating agent for a release form sheet according to claim 1, wherein (a1) the (meth) acrylate having 8 to 22 carbon atoms is stearyl methacrylate. 3. The method according to claim 1, wherein (a2) the α, β-unsaturated monomer copolymerizable with (a1) contains a nitrogen-containing α, β-unsaturated monomer. Active energy ray curable coating agent for release form sheet. 4. The reactive diluent (B) comprises: (b1) a trifunctional or more reactive diluent; and (b2) a monofunctional and / or reactive diluent.
4. The active energy ray-curable coating agent for a release form sheet according to claim 1, which comprises a bifunctional reactive diluent.