JP2005113102A - Active energy ray-curable resin composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an active energy ray-curable resin composition for a coating material for wood, which is a non-solvent type, is excellent in curability of the coating film surface, and has good adhesiveness to a base material or between layers even after irradiation with excessive active energy rays, whereby a coating film having good cracking resistance even under severely cold or hot conditions can be obtained. <P>SOLUTION: The active energy ray-curable resin composition comprises: a urethan(meth)acrylate resin (A) having a (meth)acryloyl group at its ends, which is obtained by reacting a polyisocyanate compound (a) having 2 or more isocyanate groups per molecule, at least one type of polyol (b) selected from polyester polyol, polycaprolactone polyol, and polytetramethylene ether glycol, and a hydroxy group-containing (meth)acrylate (c) represented by chemical formula (I); and a reactive diluent (B), wherein R is hydrogen or methyl, X is alkylene, and n is an integer of 2 or greater. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention can be used without a solvent, has excellent coating surface curability, has good adhesion to a substrate or between layers, and has excellent crack resistance even under severe cold conditions. The present invention relates to an active energy ray-curable resin composition for woodwork coatings from which a film is obtained.

Active energy ray curing has advantages such as energy saving, space saving, and short-time curing, and its range of use has expanded in recent years. Among these, a solventless active energy ray-curable resin composition containing a reactive diluent has attracted attention. The solvent-free active energy ray-curable resin composition is composed of a polymerizable oligomer, a reactive diluent, a polymerization initiator (not required for electron beam curing), a colorant, other additives, and the like.
As the polymerizable oligomer, unsaturated polyester resin, urethane (meth) acrylate resin, epoxy acrylate resin, and the like are used. Among them, urethane is fast-curing especially in woodwork coating, and has a high degree of freedom in resin design. Many (meth) acrylate resins are used. For example, curable resin compositions containing a urethane (meth) acrylate resin are described in JP-A Nos. 08-25964 and 10-130345. These urethane (meth) acrylate resins are designed without solvent, but when exposed to excessive active energy rays (for example, about twice the general irradiation amount), the adhesiveness is lowered and severe cold heat is applied. There was a drawback that the crack resistance was poor under the conditions.
Japanese Patent Laid-Open No. 08-25964 JP-A-10-130345

  The present invention relates to an active energy ray-curable resin composition that can be used without a solvent. More specifically, it is a solventless type, has excellent curability on the surface of the coating film, and has excellent adhesion to the substrate or between the cured coating layers even when irradiated with excessive active energy rays. An object of the present invention is to provide a urethane (meth) acrylate resin-based active energy ray-curable resin composition excellent in crack resistance even under extremely cold conditions.

Ｒは水素またはメチル基、Ｘはアルキレン基 ｎは整数で２以上
すなわち、本発明は、１分子当り２個以上のイソシアネート基を有するポリイソシアネート化合物（ａ）、ポリエステルポリオール、ポリカプロラクトンポリオール及びポリテトラメチレンエーテルグリコールから選ばれる少なくとも１種のポリオール（ｂ）、化学式（Ｉ）で示される水酸基含有（メタ）アクリレート（ｃ）を反応させて得られる、末端に（メタ）アクリロイル基を有するウレタン（メタ）アクリレート樹脂（Ａ）、並びに反応性希釈剤（Ｂ）からなる活性エネルギー線硬化性樹脂組成物に関する。The inventors of the present invention have intensively studied to solve this problem. As a result, at least one polyol (b) selected from polyisocyanate compound (a) having two or more isocyanate groups per molecule, polyester polyol, polycaprolactone polyol and polytetramethylene ether glycol, An active energy ray comprising a urethane (meth) acrylate resin (A) having a (meth) acryloyl group at the terminal obtained by reacting the hydroxyl group-containing (meth) acrylate (c) shown, and a reactive diluent (B) It has been found that this problem can be achieved by using a curable resin composition.

R represents hydrogen or a methyl group, X represents an alkylene group, n represents an integer of 2 or more. That is, the present invention relates to a polyisocyanate compound (a) having 2 or more isocyanate groups per molecule, a polyester polyol, a polycaprolactone polyol and a polytetra A urethane (meta) having a (meth) acryloyl group at the terminal, obtained by reacting at least one polyol (b) selected from methylene ether glycol and a hydroxyl group-containing (meth) acrylate (c) represented by the chemical formula (I) ) An active energy ray-curable resin composition comprising an acrylate resin (A) and a reactive diluent (B).

  As verified in Examples and Comparative Examples, according to the present invention, it is a solventless type, excellent in curability, and even under conditions of irradiating excessive UV light, between the substrate and the coating film, between the coating film and the coating film. It is clear that both have excellent adhesion and excellent crack resistance even under severe cold conditions.

  In the present invention, the polyisocyanate compound (a) is tolylene diisocyanate, hydrogenated tolylene diisocyanate, diphenylmethane diisocyanate, hydrogenated diphenylmethane diisocyanate, lysine diisocyanate, naphthalene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, xylene diisocyanate, hydrogenated xylylene diisocyanate. A diisocyanate compound such as can be used.

  Furthermore, a burette type polyisocyanate compound obtained by reacting the above various diisocyanate compounds with water, or an adduct type polyisocyanate compound obtained by reacting the above various diisocyanate compounds with a polyhydric alcohol such as trimethylolpropane. Alternatively, a multimer obtained by converting the above-mentioned various diisocyanate compounds into an isocyanurate can be used.

  In the present invention, the component (b) polyester polyol is obtained by esterifying a polyvalent carboxylic acid and a polyhydric alcohol.

  Polycarboxylic acids include adipic acid, sebacic acid, succinic acid, phthalic acid, phthalic anhydride, isophthalic acid, terephthalic acid, tetrahydrophthalic acid, tetrahydrophthalic anhydride, fumaric acid, maleic acid, maleic anhydride, itaconic acid , Known conventional ones such as trimellitic acid, trimellitic anhydride, pyromellitic acid, pyromellitic anhydride.

  Examples of polyhydric alcohols include ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, neopentyl glycol, 1,4-butanediol, 1,6-hexanediol, 3-methyl 1,5-pentanediol, and bisphenol A ethylene. Examples of the known and conventional ones include oxide or propylene oxide adduct, glycerin, trimethylolpropane, trimethylolethane, pentaerythritol, dimethylolpropionic acid, and dimethylolbutanoic acid.

  In the present invention, the component (b) polycaprolactone polyol is ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, neopentyl glycol, 1,4-butanediol, 1,6-hexanediol, ethylene oxide of bisphenol A, or Examples include propylene oxide adducts, glycerin, trimethylolpropane, trimethylolethane, and ε-caprolactone adducts of known and commonly used polyhydric alcohols such as pentaerythritol.

  In the present invention, examples of the polytetramethylene ether glycol as component (b) include known and commonly used ones produced by cationic polymerization of tetrahydrofuran.

  In the present invention, the hydroxyl group-containing (meth) acrylate represented by the chemical formula (I) is polyethylene glycol mono (meth) acrylate, polypropylene glycol mono (meth) acrylate, polyethylene glycol-polypropylene glycol mono (meth) acrylate, poly (ethylene glycol-). Known and commonly used ones such as tetramethylene glycol) mono (meth) acrylate are exemplified.

  In the present invention, a hydroxyl group-containing (meth) acrylate (d) other than the hydroxyl group-containing (meth) acrylate (c) represented by the chemical formula (I) can be used in combination as necessary. At this time, the mass ratio of the hydroxyl group-containing (meth) acrylate (c) represented by the chemical formula (I) and the other hydroxyl group-containing (meth) acrylate (d) is desirably 100: 0 to 20:80, and 80: More preferably, it is 20-30: 70. When the hydroxyl group-containing (meth) acrylate (c) represented by the chemical formula (I) is less than this range (100: 0 to 20:80), the adhesion and crack resistance tend to be inferior.

  Examples of the hydroxyl group-containing (meth) acrylate (d) other than the hydroxyl group-containing (meth) acrylate (c) represented by the chemical formula (I) used in the present invention include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl ( Examples include known and commonly used compounds such as meth) acrylate, butanediol mono (meth) acrylate, 2-hydroxyethyl (meth) acrylate modified with caprolactone, glycidol di (meth) acrylate, pentaerythritol tri (meth) acrylate.

  In the present invention, it is necessary to react the polyisocyanate compound (a), the polyol (b), and the hydroxyl group-containing (meth) acrylate (c) represented by the chemical formula (I). As the method, the hydroxyl group-containing (meth) acrylate (c) represented by the chemical formula (I) can be added to the molecular terminal via the polyisocyanate compound (a) using the hydroxyl group of the polyol (b). At this time, (1) a method of reacting the polyol (b) and the polyisocyanate compound (a) to form a terminal isocyanate oligomer, and adding the hydroxyl group-containing (meth) acrylate (c) represented by the chemical formula (I), (2) (2) Either a method of mixing the polyol (b) and the hydroxyl group-containing (meth) acrylate (c) represented by the chemical formula (I), and adding the polyisocyanate compound (a) to the reaction may be used. Moreover, you may perform by either the method of performing these reaction in a reactive diluent, and the method of melt | dissolving the obtained urethane (meth) acrylate with a reactive diluent.

  In addition, when reacting (a), (b) and (c) component, you may use a bivalent polyol or a bivalent polyamine as a chain extender as needed.

  Examples of divalent polyols include ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, neopentyl glycol, 1,4-butanediol, 1,6-hexanediol, 3-methyl 1,5-pentanediol, and bisphenol A ethylene. Well-known and conventional ones such as lenoxide or propylene oxide adduct may be mentioned.

  Divalent polyamines such as ethylenediamine, hexamethylenediamine, tolylenediamine, hydrogenated tolylenediamine, diphenylmethanediamine hydrogenated diphenylmethanediamine, tolidinediamine, naphthalenediamine, isophoronediamine, xylenediamine, hydrogenated xylenediamine, etc. Is mentioned.

  Examples of the reactive diluent (B) used in the present invention include styrene, vinyl toluene, vinyl acetate, N-vinyl pyrrolidone, N-vinyl formamide, N-vinyl caprolactam, (meth) acryloylmorpholine, cyclohexyl (meth) acrylate. , 2-ethoxyethyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, n-hexyl acrylate, cyclohexyl acrylate, isobornyl acrylate, phenoxyethyl acrylate, diethylene glycol diacrylate, 1,6-hexanediol diacrylate, neopentyl Glycol diacrylate, tripropylene glycol diacrylate, trimethylolpropane triacrylate, pentaerythritol triacrylate, pentaerythritol Tiger acrylate include those conventionally known, such as dipentaerythritol hexaacrylate.

  In the present invention, the mass ratio of the urethane (meth) acrylate resin (A) and the reactive diluent (B) is desirably 95: 5 to 25:75 (preferably 70:30 to 35:65). When the reactive diluent (B) is less than this range, the viscosity of the active energy ray-curable resin composition is high and difficult to apply, and when it is more than this range, the adhesion to the substrate decreases.

  In the present invention, when curing is performed by irradiating with ultraviolet rays, it is necessary to use a photopolymerization initiator in combination. Known photopolymerization initiators include benzyldimethyl ketal, benzoin, benzoin ethyl ether, benzoin isopropyl ether, 1-hydroxycyclohexyl phenyl ketone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, benzophenone, and the like. Conventional ones can be mentioned. These photopolymerization initiators can be used alone or in combination of two or more.

  The use ratio of these photopolymerization initiators is desirably 1 to 10 parts by mass with respect to 100 parts by mass in total of the urethane (meth) acrylate resin (A) and the reactive diluent (B). It is more preferable to use ˜7 parts by mass. When this amount is less than 1 part by mass, the curability is not sufficient, and when it exceeds 10 parts by mass, the physical properties of the obtained coating film are lowered.

  In the present invention, when curing is performed by irradiating an electron beam, a known electron beam irradiation apparatus can be used. The irradiation amount of the electron beam needs to be 1 to 10 Mrad, and more preferably 2 to 5 Mrad. If the irradiation amount is less than 1 Mrad, curing is insufficient, and if it is more than 10 Mrad, the substrate may be damaged.

  Furthermore, various polymerization inhibitors can be added as necessary.

  Examples of the polymerization inhibitor include known ones such as hydroquinone, hydroquinone monomethyl ether, benzoquinone, pt-butylcatechol, 2,6-dibutyl-4-methylphenol.

  In addition, various additives other than those described above, for example, antioxidants, antifoaming agents, leveling agents, ultraviolet absorbers, pigments and the like can be added as necessary.

  Examples will be specifically described below, but the present invention is not limited to these examples. In the following, “parts” and “%” mean “parts by mass” and “% by mass” unless otherwise specified.

[Production Example 1] Synthesis of urethane (meth) acrylate resin A A flask equipped with a stirrer, a thermometer, a reflux condenser and a nitrogen introduction tube was added to “Tesrack 2455” [polyester polyol (1 by Hitachi Chemical Polymer Co., Ltd.). , 6-hexanediol, neopentyl glycol and polyester polyol of adipic acid, number average molecular weight 2000)] 2000 parts. Next, the temperature inside the system was raised to 60 ° C. while blowing nitrogen gas, and after dissolving uniformly, 1282 parts of tolylene diisocyanate was added, the temperature was further raised to 100 ° C., and the temperature was kept for 6 hours. Thereafter, the temperature was lowered to 90 ° C., the blowing of nitrogen gas was stopped, and 2224 parts of polypropylene glycol monoacrylate (Blenmer AP400 manufactured by NOF Corporation), 954 parts of 2-hydroxyethyl acrylate, and 5.2 parts of hydroquinone monomethyl ether were added. In addition, the mixture was kept warm for 7 hours, and as a result of IR measurement, it was confirmed that the isocyanate group had disappeared, and the reaction was terminated. Thus, urethane (meth) acrylate resin A was obtained.

[Production Example 2] Synthesis of urethane (meth) acrylate resin B In a flask equipped with a stirrer, a thermometer, a reflux condenser and a nitrogen introduction tube, “PTMG2000 (trade name)” [Polytetra, manufactured by Mitsubishi Chemical Corporation] Methylene ether glycol, number average molecular weight 2000] 2000 parts were charged. Next, the temperature in the system was raised to 60 ° C. while blowing nitrogen gas, and after uniformly dissolving, 862 parts of isophorone diisocyanate was added, and then the temperature was raised to 100 ° C. and kept warm for 6 hours. Thereafter, the temperature was lowered to 90 ° C., the blowing of nitrogen gas was stopped, 269 parts of polypropylene glycol monomethacrylate (Nippon Yushi Co., Ltd., Bremer PP800), 628 parts of 2-hydroxyethyl acrylate, 3 parts of hydroquinone monomethyl ether were added, and 7 As a result of IR measurement as a result of IR measurement, it was confirmed that the isocyanate group had disappeared, and the reaction was terminated, whereby urethane (meth) acrylate resin B was obtained.

[Production Example] Synthesis of Urethane Acrylate Resin C To a flask equipped with a stirrer, thermometer, reflux condenser and nitrogen introduction tube, add “Teslac 2455” [polyester polyol (1,6-hexane, manufactured by Hitachi Chemical Polymer Co., Ltd.) Diol, neopentyl glycol and polyester polyol of adipic acid, number average molecular weight 2000)] 2000 parts. Next, the temperature inside the system was raised to 60 ° C. while blowing nitrogen gas, and after dissolving uniformly, 1282 parts of tolylene diisocyanate was added, the temperature was further raised to 100 ° C., and the temperature was kept for 6 hours. Thereafter, the temperature was lowered to 90 ° C., the blowing of nitrogen gas was stopped, 1478 parts of 2-hydroxyethyl acrylate and 3.8 parts of hydroquinone monomethyl ether were added, and the temperature was maintained for 7 hours. As a result of IR measurement, the isocyanate group disappeared. The reaction was terminated and urethane acrylate resin C was obtained.

[Production Example 4] Synthesis of urethane (meth) acrylate resin D To a flask equipped with a stirrer, thermometer, reflux condenser and nitrogen introduction tube, “PTMG2000 (trade name)” [Mitsubishi Chemical Co., Ltd. Methylene ether glycol, number average molecular weight 2000] 2000 parts were charged. Next, the temperature in the system was raised to 60 ° C. while blowing nitrogen gas, and after uniformly dissolving, 862 parts of isophorone diisocyanate was added, and then the temperature was raised to 100 ° C. and kept warm for 6 hours. Thereafter, the temperature was lowered to 90 ° C., the blowing of nitrogen gas was stopped, 112 parts of polypropylene glycol monomethacrylate (Nippon Yushi Co., Ltd., Bremer PP1000), 634 parts of 2-hydroxyethyl acrylate, and 2.9 parts of hydroquinone monomethyl ether were added. The mixture was kept warm for 7 hours, and as a result of IR measurement, it was confirmed that the isocyanate group had disappeared, and the reaction was terminated. Thus, urethane (meth) acrylate resin D was obtained.

［実施例１］Table 1 shows the mass ratio between the hydroxyl group-containing (meth) acrylate (c) represented by the chemical formula (I) of Production Examples 1 to 4 and the other hydroxyl group-containing (meth) acrylate (d).

[Example 1]

70% of the urethane (meth) acrylate resin A obtained in Production Example 1, 30 parts of tripropylene glycol diacrylate (Miramar M220 manufactured by Bigen), 3% of a photopolymerization initiator (Ciba Geigy, Irgacure 184) In addition, a test active energy ray-curable resin composition was prepared by mixing uniformly.
[Example 2]

Photopolymerization to 50 parts of urethane (meth) acrylate resin B obtained in Production Example 2, 20 parts of acryloylmorpholine (ACMO manufactured by Kojin Co., Ltd.), and 30 parts of tripropylene glycol diacrylate (Miramar M220 manufactured by Bigensha). An active energy ray-curable resin composition for testing was prepared by adding 3% of an initiator (Ciba Geigy, Irgacure 184) and mixing uniformly.
[Example 3, Comparative Examples 1 to 3]

As shown in Table 2, a test active energy ray-curable resin composition was prepared in the same manner as in Example 1.

[Curability test]
The test active energy ray-curable resin composition is applied to a glass plate with a thickness of 25 μm using an applicator, and cured by UV irradiation under the conditions of one high-pressure mercury lamp (80 W / cm), an irradiation distance of 15 cm, and a conveyor speed of 20 m / min. I checked the number of passes until.

[Adhesion]
The active energy ray-curable resin composition for test was applied to a 15 cm square veneer plywood with a bar coater at 25 g / m ² , one high pressure mercury lamp (80 W / cm), irradiation distance of 15 cm, 250 mJ / cm ² and 500 mJ / cm. ² (500mJ / cm ² over-irradiation test, usually about 250 mJ / cm ²⁾ was irradiated with UV. On the coating film, the same test curable resin composition was applied under the same conditions and UV-irradiated to make a test plate. The test plate was cut with 100 2 mm square grids with a cutter knife, and the adhesiveness between the substrate and the coating film and between the coating film layers was subjected to a cello tape peeling test, and the remaining number was counted.

[Crack resistance]
An active energy ray-curable resin composition for test was applied to a 15 cm square veneer plywood with a bar coater at 25 g / m ² , one high pressure mercury lamp (80 W / cm), an irradiation distance of 15 cm, and 500 mJ / cm ² (over irradiation amount). ) UV irradiation. On the coating film, a test top coat (urethane acrylate (Tesrack 2321, manufactured by Hitachi Chemical Co., Ltd.) / Miramar M220 = 1/1) was applied at 15 g / m ² , and the test plate was irradiated with 500 mJ / cm ² UV. Produced. The test plate was treated twice at 80 ° C. for 2 hours and at −20 ° C. for 2 hours under cold repetition conditions, and the length of cracks generated in the coating film was measured.

Claims (3)

At least one polyol (b) selected from polyisocyanate compound (a) having two or more isocyanate groups per molecule, polyester polyol, polycaprolactone polyol and polytetramethylene ether glycol, and a hydroxyl group represented by chemical formula (I) Active energy ray-curable resin comprising urethane (meth) acrylate resin (A) having a (meth) acryloyl group at the terminal, and reactive diluent (B), obtained by reacting containing (meth) acrylate (c) Composition.

R is hydrogen or a methyl group, X is an alkylene group, n is an integer and is 2 or more   2. The active energy ray-curable resin composition according to claim 1, wherein a mass ratio of the urethane (meth) acrylate resin (A) and the reactive diluent (B) is 95: 5 to 25:75. .   The active energy ray-curable resin composition according to claim 1, wherein the active energy ray is an ultraviolet ray or an electron beam.