JP2011042770A - Active energy ray-curable oligomer, active energy ray-curable resin composition, cured coating film, and plastic film - Google Patents

Abstract

An active energy ray-curable oligomer that can form a hard coat layer that is excellent in both surface hardness and flexibility is provided.
A diol compound (a1) having 1 to 5 carbon atoms, a diisocyanate compound (a2), and a general formula (1): CH ₂ ═CX— (CH ₂ ) _n — (CO) _m —O— (formula Wherein X represents H or CH ₃ , n represents 0 or 1, and m represents 0 or 1), and contains a reactant comprising a monohydroxy compound (a3) having a polymerizable functional group represented by: The active energy ray curing is characterized in that the urethane bond concentration is 3.0 × 10 ^{−3 to} 4.5 × 10 ⁻³ eq / g and the weight average molecular weight is 3,000 to 7,000. Type oligomers are used.
[Selection figure] None

Description

The present invention relates to a novel active energy ray-curable oligomer, an active energy ray-curable resin composition, a cured coating, and a plastic film.

Plastic films made from polyethylene terephthalate resin, acrylic resin, polycarbonate resin, acetylated cellulose resin, etc. are used in various industrial applications such as protective films for displays and solar films for automobile windows. Usually, a hard coat layer having high hardness and having various functions such as scratch resistance, solvent resistance, and water resistance is provided. Further, in specific applications, not only such various functions, particularly hardness, but also a contradictory performance such as good flexibility (also called followability and flexibility) may be required.

As a means for obtaining a hard coat layer having surface hardness, it is generally the mainstream to use a resin composition that is cured by an active energy ray such as ultraviolet rays or electron beams, but volume shrinkage occurs during the curing reaction. In general, internal stress tends to remain in the resulting hard coat layer, so that the flexibility is usually poor. Therefore, when a strong force (such as impact) or a large deformation is applied to the hard coat layer from the outside, cracks, cracks, and the like may occur.

  Examples of means for obtaining a hard coat layer having both surface hardness and flexibility include urethane (meth) acrylate oligomers containing 4 or more (meth) acryloyl groups, and 3 or 4 (meth) acryloyl groups. It is known to use an ultraviolet curable resin composition comprising a (meth) acrylate oligomer and a photopolymerization initiator (see Patent Document 1), but the flexibility is as high as 30 mmφ in diameter. It only means that peeling or cracking does not occur when wound on a thick cylinder (see Patent Document 1 (paragraph [0071])), and it is difficult to say that it is sufficient for recent high quality requirements. .

JP 2004-51804 A

  The present invention provides an active energy ray curable oligomer capable of forming a hard coat layer having both surface hardness and flexibility, an active energy ray curable resin composition using the same, a cured coating, and a plastic film. Let it be the main issue.

  As a result of intensive studies, the present inventor has found that the above-mentioned problems can be solved by the specific active energy ray-curable oligomer shown below.

That is, the present invention has a carbon number of 1 to 5 of the diol compound (a1), a diisocyanate compound (a2), and the general formula _{(1): CH 2 = CX-} (CH 2) n - (CO) m - (O A reaction comprising a monohydroxy compound (a3) having a polymerizable functional group represented by _l- (wherein X represents H or CH ₃ , and n, m and l all represent 0 or 1). The urethane bond concentration is 3.0 × 10 ^{−3 to} 4.5 × 10 ⁻³ eq / g, and the weight average molecular weight is 3,000 to 7,000. An active energy ray curable oligomer (A); an active energy ray curable resin composition containing the active energy ray curable oligomer (A) and a polymerization initiator (B); the active energy ray curable oligomer (A) ),polymerization An active energy ray-curable resin composition containing an initiator (B) and a reactive diluent (C); a cured film obtained by curing the active energy ray-curable resin composition; the cured film as a surface layer Related to plastic film.

  According to the active energy ray-curable oligomer of the present invention and the active energy ray-curable resin composition using the oligomer, a cured film having both good surface hardness and high flexibility can be formed. In addition, the cured film has various other functions such as scratch resistance, solvent resistance, and water resistance. Therefore, a plastic film having this cured coating as a surface layer (hard coat layer) is suitable for applications such as protective films for various displays and solar films for automobile windows.

The active energy ray-curable oligomer (A) of the present invention (hereinafter referred to as “component (A)”) is a diol compound (a1) having 1 to 5 carbon atoms (hereinafter referred to as “component (a1)”), diisocyanate compound (a2). (Hereinafter referred to as component (a2)), and general formula (1): CH ₂ = CX— (CH ₂ ) _n — (CO) _m — (O) ₁ — (wherein X represents H or CH ₃ . , N, m and l all represent 0 or 1, and a reaction product comprising a monohydroxy compound (a3) having a polymerizable functional group represented by (hereinafter referred to as component (a3)), and The urethane bond concentration is 3.0 × 10 ^{−3 to} 4.5 × 10 ⁻³ eq / g, and the weight average molecular weight is 3,000 to 7,000.

By using this component (a1), the urethane bond in the reaction product can be made dense, and as a result, the component (A1) having the urethane bond concentration within the range of the weight average molecular weight is obtained. be able to. And it becomes possible by this (A1) component to form the hard-coat layer in which surface hardness and the softness | flexibility were compatible.

As the component (a1), various known compounds can be used without particular limitation as long as they are diol compounds having 1 to 5 carbon atoms. Specifically, for example, a linear diol having 1 to 5 carbon atoms [methanediol, ethylene glycol, propylene glycol, butanediol, pentanediol, etc.] or a branched diol having 1 to 5 carbon atoms [1, 2-propylene glycol, 1,3-butanediol, neopentyl glycol, etc.] and the like. These may be used alone or in combination of two or more. Among these, a linear diol having 1 to 5 carbon atoms (preferably 1 to 3 carbon atoms) is particularly preferable from the viewpoint of achieving both the surface hardness and flexibility of the cured film. A hard coat layer having both surface hardness and flexibility cannot be formed depending on the oligomer obtained using a diol compound having 6 or more carbon atoms in place of the component (a1).

  Examples of the component (a2) include alicyclic diisocyanates [cyclohexane-1,4-diisocyanate, xylylene diisocyanate, isophorone diisocyanate, dicyclohexylmethane-4,4′-diisocyanate, etc.], aliphatic diisocyanates [1,6 -Hexane diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, hexamethylene diisocyanate, lysine diisocyanate, etc.], aromatic diisocyanate [1,5-naphthylene diisocyanate, 4,4'-diphenylmethane diisocyanate, 4,4'- Diphenyldimethylmethane diisocyanate etc.], and the like. These may be used alone or in combinations of two or more. Among these, alicyclic diisocyanates are preferable, and isophorone diisocyanate is particularly preferable from the viewpoint of achieving both the surface hardness and flexibility of the cured film.

(A3) component of the general formula in the molecule _{(1): CH 2 = CX-} (CH 2) n - (CO) m - (O) l - ( wherein, X represents H or CH _3, n , M and l each represents 0 or 1.) Any known compound can be used without particular limitation as long as it is a compound having a polymerizable functional group represented by . Examples of the polymerizable functional group include ethenyl group (CH ₂ ═CH—), vinyl ether group (CH ₂ ═CH—O—), allyl group (CH ₂ ═CH—CH ₂ —), allyl ether group (CH _2). ═CH—CH ₂ —O—), acryloyl group (CH ₂ ═CH—COO—), methacryloyl group (CH ₂ ═CCH ₃ —COO—) and the like.

As a specific example of the component (a3), specifically, as the monohydroxy compound having one polymerizable functional group, for example, monohydroxy mono (meth) acrylate [2-hydroxyethyl (meth) acrylate, 2- Hydroxypropyl (meth) acrylate etc.], monohydroxy monovinyl ether [2- (vinyloxy) ethanol, diethylene glycol monovinyl ether, triethylene glycol monovinyl ether etc.], monohydroxy monoallyl ether [2- (allyloxy) ethanol etc.], etc. It is done.
Examples of the monohydroxy compound having two polymerizable functional groups include monohydroxy di (meth) acrylate [glycerol di (meth) acrylate and the like], monohydroxy divinyl ether [trimethylolpropane divinyl ether, triethanolamine diester. Vinyl ether, etc.], monohydroxy diallyl ether [trimethylolpropane diallyl ether, diallyl glycerol, etc.] and the like.
In addition, as monohydroxy compounds having at least three polymerizable functional groups, monohydroxy poly (meth) acrylate [pentaerythritol monohydroxytri (meth) acrylate, dipentaerythritol monohydroxypenta (meth) acrylate, etc.], monohydroxy Examples include polyallyl ether [pentaerythritol monohydroxytriallyl ether, triallyl citrate, etc.]. And these can be used individually by 1 type or in combination of 2 or more types.

  Among the components (a3), from the viewpoint of coexistence of the surface hardness and flexibility of the cured film, a monohydroxy compound having at least three polymerizable functional groups, specifically, the monohydroxy poly (meth) acrylate, Particularly preferred is pentaerythritol tri (meth) acrylate.

  The component (A) contains a reaction product of the component (a1) -component, the component (a2) and the component (a3), and the reaction product can be produced by various known methods. Specifically, for example, the one-shot method in which the components (a1) to (a3) are reacted at once, or the components (a1) and (a2) are reacted once to form a urethane prepolymer, and then ( a3) A prepolymer method in which the component is reacted may be mentioned, and the prepolymer method is preferred because the structure of the component (A) can be easily controlled.

  The reaction ratio of the components (a1) and (a2) in the prepolymer method is usually such that the ratio of the number of moles of isocyanate groups (NCO) and the number of moles of hydroxyl groups (OH) of the former (NCO / OH) is 2/1. It is about ˜5 / 4, preferably 3/2. The reaction ratio between the urethane prepolymer and the component (a3) is such that the number of moles (NCO ′) of the former terminal isocyanate group and the number of moles of hydroxyl group (OH ′) of the latter are usually 1/1 to 1 / 1.5. The range is preferably 1/1 to 1 / 1.3. Moreover, the reaction temperature in both urethane reactions is about 50-150 degreeC normally.

  In the urethanization reaction, various known catalysts and solvents can be used. Examples of the catalyst include triethylenediamine, 1,8-diazabicyclo- [5,4,0] -undecene-7, stannous octylate, lead dioctylate, and the like. Moreover, as a solvent, methyl ethyl ketone, methyl isobutyl ketone, toluene etc. are mentioned as a thing which does not react easily with an isocyanate group at the time of a urethanation reaction.

The component (A) thus obtained has a urethane bond concentration (solid content conversion) of usually about 3.0 × 10 ^{−3 to} 4.5 × 10 ⁻³ eq / g, preferably 3.0 × 10 ⁻³ to 4. 0.0 × 10 ⁻³ eq / g and the weight average molecular weight is about 3,000 to 7,000, preferably 3,500 to 6,000. If either one or both of the urethane bond concentration and the weight average molecular weight deviate from the respective numerical ranges, it becomes impossible to achieve both surface hardness and flexibility.

  The active energy ray-curable resin composition of the present invention (hereinafter simply referred to as a resin composition) reacts with the component (A) and the polymerization initiator (B) (hereinafter referred to as the component (B)), and as necessary. A functional diluent (C).

  Specific examples of the component (B) include benzophenone-based polymerization initiators [benzophenone, benzoylbenzoic acid, o-benzoylbenzoic acid methyl ester, p-dimethylaminobenzoic acid ester, methyl benzoylbenzoate, phenylbenzophenone, Trimethylbenzophenone, hydroxybenzophenone, etc.), acetophenone polymerization initiator (phenoxydichloroacetophenone, butyldichloroacetophenone, diethoxyacetophenone, hydroxymethylphenylpropaneone, isopropylphenylhydroxymethylpropanone, hydroxycyclohexylphenylketone, hydroxycyclohexylphenylketone, etc.) Thioxanthone polymerization initiator [thioxanthone, chlorothioxanthone, methylthioxanthone, Ropi Lucio xanthone, dichloro thioxanthone, diethyl thioxanthone, diisopropyl thioxanthone, etc.] and the like, which may be combined alone or two or more kinds.

  Specifically, the component (C) means a monomer or oligomer (excluding the component (A)) having at least one polymerizable functional group in the molecule, and various known ones are used without particular limitation. Can do. (See, for example, “UV / EB Curing Handbook (raw material)”, edited by Kobunshi Shuppankai, 1st edition, 1st printing, issued on December 20, 1985).

  As the monomer (C), the component (a3) can be used as it is, and the monomer other than the component (a3) (that is, having the polymerizable functional group in the molecule and not having a hydroxy group). Monomers and monomers having the polymerizable functional group in the molecule and having at least two hydroxy groups can be used.

  As the monomer other than the component (a3), for example, a monofunctional monomer [2-ethylhexyl (meth) acrylate, isodecyl (meth) acrylate, isooctyl (meth) acrylate, benzyl (meth) acrylate, cyclopentanyl (meth) acrylate] Cyclohexyl (meth) acrylate, dicyclopentenyl (meth) acrylate, isobonyl (meth) acrylate, etc.], bifunctional monomer [1,3-butanediol di (meth) acrylate, 1,4-butanediol di (meth) acrylate 1,6-hexanediol di (meth) acrylate, diethylene glycol di (meth) acrylate, neopentyl glycol di (meth) acrylate, tripropylene glycol di (meth) acrylate, glycerol di (meth) acrylate Relate, allyl (meth) acrylate, epichlorohydrin modified 1,6-hexanediol acrylate, triglycerol diacrylate, etc.] Trifunctional or higher (meth) acrylate [trimethylolpropane tri (meth) acrylate, ethylene oxide modified trimethylolpropane tri (Meth) acrylate, propylene oxide modified trimethylolpropane tri (meth) acrylate, dipentaerythritol hexa (meth) acrylate, epichlorohydrin modified trimethylolpropane tri (meth) acrylate, trivinylbenzene, trivinylcyclohexane, ditrimethylolpropane tetra ( Meth) acrylate, glycerol tri (meth) acrylate, etc.], etc., and these are one kind alone or two kinds It is possible to combine the above.

  Examples of the oligomer that is component (C) include various known polyester (meth) acrylates, polyurethane (meth) acrylates, epoxy (meth) acrylates, and the like. ) Acrylate is preferred.

  The content of the component (A) to the component (C) in the resin composition of the present invention is not particularly limited. Usually, the component (B) is 0 with respect to 100 parts by weight (in terms of solid content) of the component (A). About 10 to 10 parts by weight (preferably 3 to 7 parts by weight) and component (C) is usually about 0 to 900 parts by weight (preferably 0 to 500 parts by weight).

In addition, the resin composition of the present invention may contain an antioxidant, an ultraviolet absorber, a light stabilizer, a leveling agent, a pigment, an inorganic filler, an organic filler, an organic solvent, and the like.

The cured coating of the present invention is obtained by applying the resin composition of the present invention to various substrates and curing it with active energy rays (ultraviolet rays, electron beams, etc.).

Examples of the substrate include a plastic film made of polypropylene resin, polyethylene resin, polyethylene terephthalate resin, polyethylene naphthalate resin, polymethyl methacrylate resin, polystyrene resin, and the like, and the shape is not limited. Moreover, when a base material is a film form, the thickness is about 10-200 micrometers normally.

Coating method is not particularly limited, for example, gravure coating method, reverse coating method, die coating method, lip coating method, blade coating method, roll coating method, roll coating method, knife coating method, curtain coating method, slot orifice method, Examples thereof include a spray coating method and an ink jet method.

As the ultraviolet source, for example, an high-pressure mercury lamp or a metal halide lamp or the like, the irradiation energy is usually 100~2,000mJ / cm ² approximately. Further, the electron beam supply source and the irradiation method (scanning electron beam irradiation method, curtain type electron beam irradiation method, etc.) are not particularly limited, and the irradiation energy is usually about 10 to 200 kGy.

Hereinafter, the present invention will be described in more detail through examples, but the scope of the present invention is not limited thereto. “Part” is based on weight.

<Synthesis of component (A)>
Example 1
In a reaction vessel equipped with a stirrer, a cooling tube, a dropping funnel and a nitrogen introduction tube, 273 parts of isophorone diisocyanate (hereinafter referred to as IPDI), 0.1 part of tin octylate, and 300 parts of methyl isobutyl ketone (hereinafter referred to as MIBK) were added. After charging, the temperature in the system was raised to about 100 ° C. over about 1 hour. Next, at the same temperature, 51 parts of ethylene glycol (hereinafter referred to as EG) was dropped from another dropping funnel over about 1 hour, and the temperature was maintained at 70 ° C. for 2 hours. Next, after replacing the nitrogen introduction tube with an air introduction tube, the reaction vessel was charged with 375 parts of pentaerythritol triacrylate (hereinafter referred to as PETA), 0.7 part of methoquinone and 0.1 part of tin octylate and mixed. The temperature in the system was raised to about 90 ° C. under air bubbling. Next, the reaction system was held at the same temperature for 3 hours and then cooled to obtain an active energy ray-curable oligomer (A1) (hereinafter referred to as component (A1)). The urethane bond concentration of the component (A1) was about 3.5 × 10 ⁻³ eq / g, and the weight average molecular weight was about 5,000.

The urethane bond concentration is a value obtained by dividing the number of moles of the urethane bond in the component (A1) by the solid content weight of the component (A1). Specifically, [[weight of IPDI (273 g) / IPDI Molecular weight (222 g / mol)] × number of NCO groups (2)] / [(A1) solid content weight of the reactant (IPDI weight (273 g) + EG weight (51 g) + PETA weight (375 g) ] ≈3.5 × 10 ⁻³ eq / g (hereinafter, the same method is used).

The weight average molecular weight was measured using a commercially available column (manufactured by Tosoh Corporation, trade names “SuperG100H” and “SuperG200H”) using a commercially available gel permeation chromatography apparatus (trade name “HLC-8220”, manufactured by Tosoh Corporation). )) (The same applies hereinafter).

Example 2
After charging 235 parts of IPDI, 0.1 part of tin octylate and 300 parts of MIBK in the same reaction vessel as in Example 1, the temperature in the system was raised to about 100 ° C. over about 1 hour. . Next, at the same temperature, 36 parts of EG was dropped from another dropping funnel over about 1 hour, and the temperature was maintained at 70 ° C. for another 2 hours. Next, the nitrogen inlet tube was replaced with an air inlet tube, 429 parts of PETA, 0.7 part of methoquinone, and 0.1 part of tin octylate were charged and mixed, and then the temperature in the system was reduced to approx. The temperature was raised to 90 ° C. Next, the reaction system was maintained at the same temperature for 3 hours, and then cooled to obtain a solution of an active energy ray-curable oligomer (A2) (hereinafter referred to as component (A2)). The urethane bond concentration of the component (A2) was about 3.0 × 10 ⁻³ eq / g, and the weight average molecular weight was about 4,000.

Example 3
After charging 342 parts of IPDI, 0.1 part of tin octylate and 300 parts of MIBK in the same reaction vessel as in Example 1, the temperature in the system was raised to about 100 ° C. over about 1 hour. . Next, at the same temperature, 76 parts of EG was dropped from another dropping funnel over about 1 hour, and the temperature was maintained at 70 ° C. for another 2 hours. Next, the nitrogen introduction tube was replaced with an air introduction tube, and 281 parts of PETA, 0.7 part of methoquinone and 0.1 part of tin octylate were charged into the reaction vessel and mixed, and then the system was placed under air bubbling. The temperature of was raised to 90 ° C. Subsequently, the mixture was kept at the same temperature for 3 hours and then cooled to obtain a solution of an active energy ray-curable oligomer (A3) (hereinafter referred to as component (A3)). The urethane bond concentration of the component (A3) was about 4.4 × 10 ⁻³ eq / g, and the weight average molecular weight was about 6,000.

Comparative Example 1
After charging 219 parts of IPDI, 0.1 part of tin octylate and 300 parts of MIBK in the same reaction vessel as in Example 1, the temperature in the system was raised to about 100 ° C. over about 1 hour. did. Next, 31 parts of EG was dropped from another dropping funnel over about 1 hour at the same temperature, and the temperature was maintained at 70 ° C. for another 2 hours. Next, the nitrogen introduction tube is replaced with an air introduction tube, 450 parts of PETA, 0.7 part of methoquinone and 0.1 part of tin octylate are charged and mixed, and then the temperature inside the system is adjusted under air bubbling. The temperature was raised to 90 ° C. Next, the reaction system was kept at the same temperature for 3 hours and then cooled to obtain a solution of the active energy ray-curable oligomer (A) (hereinafter referred to as component (A)). The component (a) had a urethane bond concentration of about 2.8 × 10 ⁻³ eq / g and a weight average molecular weight of about 2,800.

Comparative Example 2
In a reaction vessel similar to that in Example 1, 365 parts of IPDI, 0.1 part of tin octylate and 300 parts of MIBK were charged, and then the temperature in the system was raised to about 100 ° C. over about 1 hour. . Next, at the same temperature, 84.9 parts of EG was dropped from another dropping funnel over about 1 hour, and the temperature was maintained at 70 ° C. for another 2 hours. Next, the nitrogen introduction tube was replaced with an air introduction tube, and 250 parts of PETA, 0.7 part of methoquinone and 0.1 part of tin octylate were charged and mixed in the reaction vessel. The temperature was raised to about 90 ° C. Next, the reaction system was held at the same temperature for 3 hours, and then cooled to obtain a solution of an active energy ray-curable oligomer (B) (hereinafter referred to as (B) component). The component (b) had a urethane bond concentration of about 4.7 × 10 ⁻³ eq / g and a weight average molecular weight of about 8,000.

Comparative Example 3
In a reaction vessel similar to Example 1, 257 parts of IPDI, 0.1 part of tin octylate and 300 parts of MIBK were charged, and then the temperature in the system was raised to about 100 ° C. over about 1 hour. Next, at the same temperature, 91 parts of 1,6-hexanediol (hereinafter referred to as 1,6-HD) is dropped over about 1 hour from another dropping funnel, and the temperature is maintained for 2 hours. The temperature was 70 ° C. Next, the nitrogen introduction tube was replaced with an air introduction tube, and 352 parts of PETA, 0.7 part of methoquinone and 0.1 part of tin octylate were charged into the reaction vessel and mixed, and then the system was placed under air bubbling. Was raised to about 90 ° C. Next, the reaction system was held at the same temperature for 3 hours and then cooled to obtain a solution of an active energy ray-curable oligomer (c) (hereinafter referred to as component (c)). Component (c) had a urethane bond concentration of about 3.3 × 10 ⁻³ eq / g and a weight average molecular weight of about 10,000.

Comparative Example 4
In a reaction vessel similar to Example 1, 137 parts of IPDI, 563 parts of PETA, 0.7 part of methoquinone, 0.1 part of tin octylate, and 300 parts of MIBK were charged under air bubbling. The temperature was raised to 90 ° C. Next, the reaction system was kept at the same temperature for 3 hours and then cooled to obtain a solution of an active energy ray-curable oligomer (d) (hereinafter referred to as component (d)). The urethane bond concentration of component (d) was about 1.8 × 10 ⁻³ eq / g, and the weight average molecular weight was about 1,500.

Examples 4-6, Comparative Examples 5-8
<Preparation of resin composition: (C) component non-use>
1-hydroxy-cyclohexyl-phenyl ketone (trade name: Irgacure 184, manufactured by Ciba Japan, hereinafter abbreviated as “Irg184”) as component (A1) and (B), and MIBK as a solvent The resin composition was obtained by mixing at a ratio (weight standard) shown in 2. Resin compositions were obtained in the same manner for components (A2) to (d).

Examples 7-9, Comparative Examples 9-12
<Preparation of resin composition: use of component (C)>
The ratio (weight) of (A1) component and Irg184 as (B) component, and polyester polyacrylate (trade name: Biscote 300, manufactured by Osaka Organic Chemical Industry Co., Ltd.) and MIBK as (C) component Standard) was mixed to obtain a resin composition. Resin compositions were obtained in the same manner for components (A2) to (d).

<Creation of cured film>
The resin composition according to Example 4 was applied onto a polyethylene terephthalate (PET) film having a film thickness of 75 μm with a # 20 bar coater (calculated value: film thickness 10 μm) and dried at 80 ° C. for 1 minute. Subsequently, the obtained film was subjected to an ultraviolet curing device (product name: UBT-080-7A / BM, manufactured by Multiply Co., Ltd.) (high pressure mercury lamp (600 mJ / cm 2)) to obtain a plastic film provided with a cured film. The same applies to the resin compositions of Examples 5 to 9 and Comparative Examples 5 to 12.

<Evaluation of cured film>
(1) Pencil hardness About the plastic film which concerns on Example 4, according to JISK5600-5-4, the hardness of the cured film was evaluated by the pencil scratch test of the load of 500g. The same applies to the plastic films according to Examples 5 to 9 and Comparative Examples 5 to 12. The results are shown in Tables 2 and 3.

(2) Flexibility According to the cylindrical mandrel method (type 1 test apparatus) described in JIS K5600-5-1, a cured film is obtained using a mandrel having a diameter of 8 mm and a diameter of 3 mm for the plastic film according to Example 4. The bending resistance (index of flexibility) was evaluated. The same applies to the plastic films according to Examples 5 to 9 and Comparative Examples 5 to 12. The results are shown in Tables 2 and 3. In addition, (circle) means that a crack and a crack did not arise in a cured film, and x produced.

Claims (9)

Carbon atoms 1 to 5 of the diol compound (a1), a diisocyanate compound (a2), and the general formula _{(1): CH 2 = CX-} (CH 2) n - (CO) m - (O) l - ( wherein , X represents H or CH ₃ , and n, m and l all represent 0 or 1), and a reaction product comprising a monohydroxy compound (a3) having a polymerizable functional group represented by: The active energy ray curing is characterized in that the urethane bond concentration is 3.0 × 10 ^{−3 to} 4.5 × 10 ⁻³ eq / g and the weight average molecular weight is 3,000 to 7,000. Type oligomer (A). The active energy ray-curable oligomer (A) according to claim 1, wherein the component (a1) is a linear diol having 1 to 5 carbon atoms. The active energy ray-curable oligomer (A) according to claim 1 or 2, wherein the component (a2) is an alicyclic diisocyanate. The active energy ray-curable oligomer (A) according to any one of claims 1 to 3, wherein the component (a3) is monohydroxy poly (meth) acrylate. An active energy ray-curable resin composition comprising the active energy ray-curable oligomer (A) according to any one of claims 1 to 4 and a polymerization initiator (B). The active energy ray-curable resin composition according to claim 5, further comprising a reactive diluent (C). The active energy ray-curable resin composition according to claim 6, wherein the component (C) is a polyester poly (meth) acrylate. A cured film obtained by curing the active energy ray-curable resin composition according to claim 5. A plastic film having the cured film according to claim 8 as a surface layer.