JP2001200024A - Photocurable resin composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a urethane (meth)acrylate resin-based, photocurable resin composition for a woodwork coating which is solvent-free, good in coating stability and excellent in workability as well as in curability, adhesion and crack resistance. SOLUTION: This photocurable resin composition comprises a urethane (meth) acrylate resin (A) bearing a (meth)acryloyl group at its end obtained by reacting a polyisocyanate compound bearing at least two isocyanate groups in one molecule with a poly-ε-caprolactone polyol and a hydroxyl group-containing (meth) acrylate, an acryloylmorpholine (B) and a photopolymerization initiator (C).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD [0001] The present invention can be used without solvent, has good paint stability and excellent workability, has little change over time of a cured coating film, and has good adhesion to a substrate. The present invention relates to a photocurable resin composition for woodwork paints, which has excellent curability on the surface of a coating film and provides a coating film having excellent crack resistance even under severe cold conditions.

[0002]

2. Description of the Related Art Conventionally, resin compositions that are cured by irradiation with light such as ultraviolet rays have been put to practical use for paints such as plastics, paper, and woodwork, adhesives, and printing inks.

Curing by light such as ultraviolet light involves designing a photocurable resin composition which is (1) fast-curing, has high productivity, and (2) contains no solvent and is almost 100% cured. And (3) there is no need to heat and cure, so that there is little influence of heat on the base material. As the photocurable resin composition, unsaturated polyester resin, urethane acrylate resin, epoxy acrylate resin, etc. are used. Among them, urethane is used because of its quick curing property, especially in woodwork coating, and a high degree of freedom in resin design. Acrylate resins are often used.

In recent years, wood-based plywood made of inexpensive imported wood of poor quality has been increasing in the field of woodwork coating. Urethane (meth) acrylate resin-based photocurable resin compositions have been developed as being applicable to such wood-based plywood. However, most urethane (meth) acrylate-based photocurable resin compositions contain an organic solvent, and it has been strongly desired to eliminate the solvent. Attempts have been made to develop a non-solvent type photocurable resin composition, but those with good paint stability and excellent workability, and excellent in curability, adhesion to substrates, crack resistance, etc. have been obtained. It was not done at the moment.

[0005]

SUMMARY OF THE INVENTION The present invention eliminates the above-mentioned disadvantages of the prior art, and is a solvent-free urethane (meth) acrylate resin-based light having excellent curability, adhesion to a substrate, and crack resistance. An object is to provide a curable resin composition.

[0006]

Means for Solving the Problems The present inventors have intensively studied to solve this problem. As a result, a polyisocyanate compound (a) having two or more isocyanate groups per molecule, a poly-ε having a melting point of 40 ° C or less and a number average molecular weight of 500 to 3500.
Urethane (meth) having a (meth) acryloyl group at a terminal obtained by reacting a caprolactone polyol (b) and a hydroxyl group-containing (meth) acrylate (c)
It has been found that this problem can be achieved by using a photocurable resin composition containing an acrylate resin (A), acryloylmorpholine (B), and a photopolymerization initiator (C), thereby completing the present invention. Was.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, a polyisocyanate compound (a) is selected from tolylene diisocyanate, hydrogenated tolylene diisocyanate, diphenylmethane diisocyanate, hydrogenated diphenylmethane diisocyanate, tolidine diisocyanate, naphthalene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, Diisocyanate compounds such as diisocyanate and hydrogenated xylylene diisocyanate can be used.

Further, a buret type polyisocyanate compound obtained by reacting the above various diisocyanate compounds with water, or an adduct type obtained by reacting the above various diisocyanate compounds with a polyhydric alcohol such as trimethylolpropane. A polyisocyanate compound or a polymer obtained by isocyanurating the above various diisocyanate compounds can be used.

The poly-ε-caprolactone polyol (b) used in the present invention needs to have a melting point of 40 ° C. or lower, and is more preferably liquid at room temperature.
If the melting point of the poly-ε-caprolactone polyol exceeds 40 ° C., the resulting photocurable resin composition tends to crystallize, so that the paint stability and workability deteriorate, and the physical properties of the cured coating film deteriorate.

In the present invention, the poly-ε-caprolactone polyol (b) has a number average molecular weight of 1500 to 350.
It must be 0, and more preferably 2000 to 3000. When the number average molecular weight is less than 1500, the cured coating film becomes brittle, and when it exceeds 3500, the curability and the strength of the cured coating film are insufficient, and the crack resistance decreases.

Examples of the poly-ε-caprolactone polyol used in the present invention include Praxel L220AL, Praxel L220PL, Praxel L220PM, Praxel L230AL, Praxel L320AL, Praxel L330AL, Praxel 220NP1 manufactured by Daicel Chemical Industries, Ltd. .

In the present invention, the hydroxyl group-containing (meth) acrylate (c) is 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, butanediol mono (meth) acrylate, 2-hydroxyethyl (meth) Known examples include a caprolactone-modified acrylate, glycidol di (meth) acrylate, and pentaerythritol tri (meth) acrylate.

In the present invention, it is necessary to react the polyisocyanate compound (a), the poly-ε-caprolactone polyol (b), and the hydroxyl group-containing (meth) acrylate (c). As the method, poly-ε-
Utilizing the hydroxyl group of the caprolactone polyol (b), the hydroxyl group-containing (meth) acrylate (c) can be added to the molecular terminal via the polyisocyanate compound (a). At this time, (I) a method of reacting the poly-ε-caprolactone polyol (b) with the polyisocyanate compound (a) to form a terminal isocyanate oligomer and adding a hydroxyl group-containing (meth) acrylate (c);
I) The method may be carried out by either mixing the poly-ε-caprolactone polyol (b) and the hydroxyl group-containing (meth) acrylate (c), adding the polyisocyanate compound (a), and reacting the mixture. These reactions may be performed in either acryloyl morpholine (B) or by dissolving the (meth) acrylate obtained with acryloyl morpholine (B).

In the present invention, the polyisocyanate (a)
And the equivalent ratio (p) :( q) of the isocyanate group equivalent number (p) of the poly-ε-caprolactone polyol (b) to the hydroxyl equivalent number (q) is 1.50 to 3.00: 1.00. And more preferably 1.80 to 2.70: 1.00. If the polyisocyanate (a) component has an isocyanate group equivalent number of more than 3.00 with respect to 1 equivalent of the hydroxyl group of the poly-ε-caprolactone polyol (b) component, physical properties of the cured coating film such as crack resistance are reduced, and less than 1.50. If so, the curability will be poor. In addition, hydroxyl group containing (meta)
The hydroxyl equivalent (r) of the acrylate (c) component is 0.95
* ((P)-(q)) to 1.05 * ((p)-(q))
0.98 * ((p)-(q)) ~
1.02 * ((p)-(q)) is more preferable. If (r) exceeds 1.05 * ((p)-(q)), the crack resistance will decrease, and if it is less than 0.95 * ((p)-(q)), the curability will deteriorate.

In the present invention, the mass ratio of the urethane (meth) acrylate resin (A) to the acryloylmorpholine (B) is desirably 90 to 40:10 to 60.
0 to 60: 20 to 40 is more preferable. If this mass ratio is less than 40/60, the properties of the cured coating film such as curability, adhesion, and cracking resistance are reduced.
If it exceeds 10, the viscosity of the photocurable resin composition obtained will increase, and workability will decrease.

The acryloylmorpholine (B) used in the present invention can be used alone or in combination with other photopolymerizable monomers. At that time, the mass ratio of acryloyl morpholine to other photopolymerizable monomer was 1
00 to 40: 0 to 60, 100 to 8
0: 0 is more preferable. If the mass ratio is less than 40/60, the properties of the cured coating film such as curability, adhesion, and crack resistance are reduced.

Other photopolymerizable monomers used in the present invention include styrene, vinyl toluene, vinyl acetate, N
-Vinylpyrrolidone, N-vinylformamide, N-vinylcaprolactam, (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 tetra Acrylates, known and commonly used such as dipentaerythritol hexaacrylate It is.

In the present invention, the photopolymerization initiator (C) is
Benzyl dimethyl ketal, benzoin, benzoin ethyl ether, benzoin isopropyl ether, 1-
Hydroxycyclohexyl phenyl ketone, 2-hydroxy-2-methyl-1-phenylpropan-1-one,
Known examples such as benzophenone can be used. These photopolymerization initiators can be used alone or in combination of two or more.

The proportion of the photopolymerization initiator (C) used is 1 to 10 parts by mass based on 100 parts by mass of the urethane (meth) acrylate resin (A) and the acryloylmorpholine (B) in total. Preferably 2-7
It is more desirable to use parts by weight. If the amount is less than 1 part by mass, the curability is not sufficient, and if it exceeds 10 parts by mass, the physical properties of the obtained coating film deteriorate.

Further, various polymerization inhibitors can be added as required.

Examples of the polymerization inhibitor include hydroquinone, hydroquinone monomethyl ether, benzoquinone, p-
Known ones such as t-butylcatechol and 2,6-dibutyl-4-methylphenol are exemplified.

Further, if necessary, various additives other than those described above, for example, an antioxidant, an antifoaming agent, a leveling agent,
Known and commonly used substances such as ultraviolet absorbers and pigments can also be added.

[0023]

EXAMPLES Hereinafter, the present invention will be described specifically with reference to Examples, but the present invention is not limited to these Examples. Hereinafter, “parts” and “%” are “parts by mass” and “% by mass”, respectively, unless otherwise specified.

Production Example 1 (Urethane acrylate resin A
In a flask equipped with a stirrer, a thermometer, a reflux condenser, and a nitrogen inlet tube, “Placcel 220AL (trade name)” [poly-ε-caprolactone polyol manufactured by Daicel Chemical Industries, Ltd., number average molecular weight 2000 , Liquid at room temperature)] 200
0 parts were charged. Next, the temperature inside the system was raised to 60 ° C. while blowing nitrogen gas, and after uniformly dissolving, 400 parts of isophorone diisocyanate was added, and then the temperature was raised to 100 ° C. and kept for 6 hours. Thereafter, the temperature was lowered to 90 ° C., the blowing of nitrogen gas was stopped, and 186 parts of 2-hydroxyethyl acrylate and hydroquinone monomethyl ether were used.
Two parts were added, and the mixture was kept warm for 7 hours. As a result of IR measurement, it was confirmed that the isocyanate group had disappeared, and the reaction was terminated. Thus, a urethane acrylate resin A having a number average molecular weight of 3,000 was obtained.

Production Example 2 (Urethane acrylate resin B
Synthesis of “Placcel L220AL” in the same synthesis apparatus as in Example 1.
(Trade name)] [Poly-ε- manufactured by Daicel Chemical Industries, Ltd.
(Caprolactone polyol, liquid at room temperature)]. Next, while blowing in nitrogen gas, the inside of the system is
After the mixture was uniformly dissolved, 300 parts of tolylene diisocyanate was added. Then, the mixture was heated to 100 ° C. and kept for 4 hours. Thereafter, the temperature was lowered to 90 ° C., the blowing of nitrogen gas was stopped, and 2-hydroxyethyl acrylate 168 was removed.
And 2.2 parts of hydroquinone monomethyl ether, and the mixture was kept warm for 7 hours. As a result of IR measurement, it was confirmed that the isocyanate group had disappeared and the reaction was terminated to obtain a urethane acrylate resin B having a number average molecular weight of 2,800. .

Production Example 3 (Urethane acrylate resin C
2,000 parts of “Placcel 220N (trade name)” (poly-ε-caprolactone polyol manufactured by Daicel Chemical Industries, Ltd., number average molecular weight 2,000, liquid at room temperature)] were charged into the same synthesis apparatus as in Example 1. . Next, while blowing nitrogen gas, the inside of the system was heated to 60 ° C. and uniformly dissolved, and then 450 parts of isophorone diisocyanate was added.
The temperature was raised to 0 ° C and kept for 4 hours. Thereafter, the temperature was lowered to 90 ° C., the blowing of nitrogen gas was stopped, 238 parts of 2-hydroxyethyl acrylate and 2.2 parts of hydroquinone monomethyl ether were added, and the mixture was kept warm for 7 hours. As a result of IR measurement, it was confirmed that the isocyanate groups had disappeared. After the confirmation, the reaction was completed, and a urethane acrylate resin C having a number average molecular weight of 2500 was obtained.

Production Example 4 (Urethane acrylate resin D
Synthesis of “Placcel 220 (trade name)” [poly-ε-caprolactone polyol manufactured by Daicel Chemical Industries, Ltd., number average molecular weight 2000, melting point 50] in the same synthesis apparatus as in Example 1.
° C)] 2000 parts. Next, while blowing nitrogen gas, the inside of the system was heated to 60 ° C. and uniformly dissolved, and then 480 parts of isophorone diisocyanate was added.
The temperature was raised to 0 ° C and kept for 4 hours. Thereafter, the temperature was lowered to 90 ° C., the blowing of nitrogen gas was stopped, 270 parts of 2-hydroxyethyl acrylate and 2.3 parts of hydroquinone monomethyl ether were added, and the mixture was reacted for 8 hours. As a result of IR measurement, the disappearance of the isocyanate group was confirmed. After the confirmation, the reaction was completed, and a urethane acrylate resin D having a number average molecular weight of 3000 was obtained.

Table 1 shows the composition (equivalent number) in Production Examples 1 to 4.

[Table 1]

Example 1 The urethane acrylate resin A obtained in Production Example 1 was mixed with 70
Parts, acryloyl morpholine (B) and 30 parts of a photopolymerization initiator (Irgacure 651 manufactured by Ciba Geigy)
% And uniformly mixed to prepare a test photocurable resin composition.

Examples 2 to 3 and Comparative Examples 1 to 3 As shown in Table 2, in Examples and Comparative Examples, photocurable resin compositions for testing were prepared in the same manner as in Example 1.

[Table 2]

(1) Stability of Paint The photocurable resin composition for test in Table 2 was allowed to stand at 5 ° C. for 7 days.

(2) Curability Test The photocurable resin composition for test was applied to a glass plate with a thickness of 25 μm using an applicator, and a high-pressure mercury lamp (80 W / cm) was used.
1 light, irradiation distance 15cm, conveyor speed 20m /
UV irradiation was performed under the conditions of minutes, and the number of passes until curing was performed was examined.

(3) Adhesion A test photocurable resin composition was applied to a 15 cm square veneer plywood with a bar coater at a rate of 25 g / m ² , and a high-pressure mercury lamp (80
(W / cm) One lamp, irradiation distance of 15 cm, and conveyor speed of 20 m / min were irradiated with UV as many times as the number of passes obtained in the above curability test to obtain a test plate. This test plate was cut into 100 2 mm square grids with a cutter knife and subjected to a cellophane tape peeling test to examine the adhesion.

(4) Crack Resistance A test plate produced in the same manner as in the adhesion test was treated twice at 80 ° C. for 2 hours and at −20 ° C. for 2 hours under repeated cold / hot conditions, and then cracks generated in the coating film Was measured for length.

[Table 3]

EFFECT OF THE INVENTION The photocurable resin composition of the present invention has good paint stability and excellent workability while being solventless as shown in the examples, and has good photocurability, adhesion and crack resistance. Also excellent.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4J027 AG03 BA13 CB10 CC03 CD08 4J038 FA171 FA172 FA281 FA282 KA03 MA14 NA11 NA12 NA23 NA26 PA17 PC06 PC08 PC10 4J100 AL08P AM21Q BA04Q BA21P BA39P CA04 DA01 DA24 JA37

Claims (3)

[Claims] 1. A polyisocyanate compound (a) having two or more isocyanate groups per molecule, having a melting point of 40
(Meth) acryloyl at the terminal obtained by reacting poly-ε-caprolactone polyol (b) with a hydroxyl group-containing (meth) acrylate (c), wherein the number average molecular weight is 500 to 3500 at ℃ or less. A photocurable resin composition comprising a urethane (meth) acrylate resin having a group (A), acryloylmorpholine (B), and a photopolymerization initiator (C). 2. The isocyanate group equivalent number (p) of the polyisocyanate compound (a), the hydroxyl equivalent number (q) of the poly-ε-caprolactone polyol (b), and the hydroxyl equivalent of the hydroxyl group-containing (meth) acrylate (c). The relationship with the number (r) is (p) :( q) is 1.50 to 3.00: 1.
0, and 0.95 * ((p)-(q)) ≦ (r) ≦ 1.05 *
The photocurable resin composition according to claim 1, wherein ((p)-(q)) (* is a symbol representing multiplication). 3. The mass ratio of said urethane (meth) acrylate resin (A) to acryloylmorpholine (B) is 9
The photocurable resin composition according to claim 1, comprising 0 to 40:10 to 60.