JPH07103328B2 - Active energy ray curable coating composition - Google Patents

Description

TECHNICAL FIELD The present invention relates to an active energy ray-curable coating composition, and more specifically, it is applied for a very short time by applying a low viscosity and irradiating with an ultraviolet ray or an electron beam. The present invention relates to an active energy ray-curable coating composition which is cured to a good temperature, has excellent workability such as adhesion to a substrate and bendability and has good gloss.

(Prior Art) In recent years, active energy ray curable coating compositions have been extensively researched, and among them, practical application is progressing in the fields of printing inks, clear varnishes, paints, coating agents, photoresists and the like. Has been. These are composed of a monomer and a prepolymer having radical polymerizability and, if necessary, a photopolymerization initiator, an organic solvent, a pigment and the like.

(Problems to be Solved by the Invention) Generally, an active energy ray-curable monomer and a prepolymer are instantly cured by irradiation with an active energy ray, so that an internal stress is generated in a cured film. For this reason, when the curable coating composition is applied and cured, cracks are likely to occur when bent, and the adhesion is poor. In addition, high-speed curing requires high-speed coating, but these monomers and prepolymers generally have high viscosities, and the low viscosity required for high-speed coating such as spray coating and gravure / flexo printing. Is required.

(Means for Solving the Problems) As a result of earnest research to improve these drawbacks, the present invention can be applied with a low viscosity, has a fast curing speed, and has excellent workability such as adhesion to a substrate and bendability. The inventors have invented an active energy ray-curable coating composition which is excellent and has good gloss.

That is, the invention relates to A. 20-80 parts of a compound of structural formula I (In the formula, the average value of n is 1 to 3.) B. Compound of structural formula II 5 to 50 parts (In the formula, the average value of m is 1 to 3, the average value of a is 0 to 6, c
The average value of is 0 to 3, and a + b + c = 6. C. Compounds of structural formula III 0-40 parts, preferably 5-30 parts D. Monomers or prepolymers copolymerizable with A, B, C 0
-40 parts A + B + C + D = 100 parts, on the other hand, E. photopolymerization initiator 0-10 parts F. organic solvent 0-150 parts, which is an active energy ray-curable coating composition.

As the resin corresponding to the component A, polyester acrylate, urethane-modified acrylate, alkyd acrylate, epoxy acrylate, etc. can be considered, but bisphenol A has a high curing speed, good adhesion, good gloss and little coloring. An acrylated compound of an epichlorohydrin-based epoxy resin having a small molecular weight and a comparatively low viscosity is preferable. Where n is 3
If it exceeds, the viscosity will be high and the curing speed will be slow.

As the component B, the compound of structural formula II has a fast curing rate, good gloss, and no coloring. When b of Structural Formula II is large, the curing rate is high, but the bending workability is somewhat poor because it is hard. Increasing a or c in Structural Formula II improves flexibility. If softness is required, flexibility can be increased by increasing the amount of the compound of structural formula III.

By adding other monomers or prepolymers of D, it is possible to impart the performance which is not slippery only by A, B and C. For example, it is possible to mix a low-viscosity monomer in order to reduce the viscosity at the time of coating without an organic solvent, or to add a prepolymer or a monomer having good adhesion to further improve the adhesion.

Examples of the monomer include methyl acrylate, ethyl acrylate, butyl acrylate, cyclohexyl acrylate, 2-ethylhexyl acrylate, dodecyl acrylate, stearyl acrylate, dicyclopentenyl acrylate, dicyclopentenyloxyethyl acrylate, isobornyl acrylate, adamantyl acrylate, 2- Hydroxyethyl acrylate, 2-hydroxypropyl acrylate, tetrahydrofurfuryl acrylate and corresponding monofunctional monomers such as methacrylate and ethylene glycol, propylene glycol, 1,4-butanediol, diethylene glycol, triethylene glycol, polyethylene glycol, 1, 6-hexanediol, neopentyl glycol, trisic Decanol dimethylol, cyclohexane dimethanol, bisphenol A ethylene oxide adducts and other dialcohols, diesters of these ethylene oxide, propylene oxide and lactone modified products with α, β-unsaturated carboxylic acids, trimethylol propane, pentaerythritol , Tris (2-
Examples thereof include hydroxyethyl) isocyanurate, polyol compounds such as melamine polymethylol compounds, diesters of ethylene oxide, propylene oxide, lactone-modified products thereof with α, β-unsaturated carboxylic acids, and polyfunctional monomers such as polyesters. .

Examples of the prepolymer include a compound obtained by adding α, β-unsaturated carboxylic acid to a polyepoxy compound such as a novolac type epoxy resin (so-called epoxy acrylate), a polyisocyanate compound such as tolylene diisocyanate, hexamethylene diisocyanate, and α, β.
A compound to which a hydroxylalkyl ester of an unsaturated carboxylic acid has been added (so-called urethane acrylate),
A condensate of polyester and α, β-unsaturated carboxylic acid,
Other examples include epoxy modified resins, polyurethanes, polyesters, silicone resins, polybutadienes, alkyd resins, phenol resins, petroleum resins, and other acrylate-modified and methacrylate-modified products other than those mentioned above.

A, B, C, D are all 100 parts, and the compound of structural formula I is 20-80
Parts, 5 to 50 parts of the compound of structural formula II, 0 to 40 parts of the compound of structural formula III, and 0 to 40 parts of other copolymerizable monomers and prepolymers.
The inventor has invented that the resin has good properties such as adhesion, bending workability (hardness), and gloss.

The present invention relates to a coating composition which is cured by irradiating with active energy rays, but in the case of curing by irradiating with ultraviolet rays, a photopolymerization initiator must be added. The amount is 10 parts or less, preferably 2 to 5 parts, based on 100 parts of A, B, C and D in total. It is not necessary to add it when it is cured by irradiation with an electron beam.

The photopolymerization initiator may be any known photopolymerization initiator.

For example, benzoin alkyl ethers such as benzoin ethyl ether and benzoin isobutyl ether, 2,
2-diethoxyacetophenone, 4'-phenoxy-2,2
-Acetophenone series such as dichloroacetophenone, 2
-Hydroxy-2-methylpropiophenone, propiophenone such as 4'-isopropyl-2-hydroxy-2-methylpropiophenone, benzyldimethylketal, 1-hydroxycyclohexylphenyl ketone and 2-ethylanthraquinone, 2 Examples thereof include anthraquinone-based photopolymerization initiators such as chloranthraquinone and thioxanthone-based photopolymerization initiators such as 2-chlorothioxanthone and 2,4-diethylthioxanthone.

The composition of the present invention may or may not be added with an organic solvent, but the organic solvent is used to adjust the viscosity and improve the adhesion depending on the application. When an organic solvent is added, it is desirable to remove it with a hot air dryer after coating. For that purpose, it is better to add a small amount. Depending on the coating method, it may be diluted with a large amount of solvent. 150 parts or less of an organic solvent is mixed with 100 parts of the total resin content of A, B, C and D. It is preferably 80 parts or less. The type of the organic solvent is not particularly limited, but it is desirable that the solvent has a boiling point of 70 to 150 ° C. and is as harmless and safe as possible in consideration of removal by hot air drying after coating. For example, esters such as ethyl acetate and butyl acetate,
Aromatic hydrocarbons such as toluene and xylene, and ketones such as methyl ethyl ketone and methyl isobutyl ketone are often used. It is often used as a mixed solvent including other solvents.

The composition of the present invention may contain additives such as pigments, dyes, defoaming agents, leveling agents, slip agents and matting agents, if necessary.

(Example) Reaction product 1. Reaction product of Shell Co. product Epicoat # 828 and acrylic acid, and acrylic acid and epoxy group reacted in equal amounts. Corresponds to = 1 in the compound of structural formula I.

Reaction product 2. Reaction product of Epicoat # 834 manufactured by Shell Co. and acrylic acid, which is obtained by reacting acrylic acid and epoxy group in the same amount. Corresponds to = 2 in compounds of structural formula I.

Reaction product 3. Reaction product of Shell Co.'s Epicoat # 1004 and acrylic acid, and equivalent reaction of acrylic acid and epoxy group. This corresponds to ≈5 for the compound of structural formula I.

As the component B, the following was used.

1. Dipentaerythritol hexaacrylate (using Kayarad DPHA manufactured by Nippon Kayaku Co., Ltd. corresponding to = 0, = 6, and = 0 of Structural Formula II) 2. Caprolactone-modified dipentaerythritol hexaacrylate (of Structural Formula II = 1, = 3, = 3,
KAYARAD DPCA-30 manufactured by Nippon Kayaku Co., Ltd. corresponding to = 0 was used.) 3. Caprolactone-modified dipentaerythritol hexaacrylate (= 1, = 6, = 0 in the structural formula II,
Kayarad DPCA-60 manufactured by Nippon Kayaku Co., Ltd. corresponding to = 0 was used. 4. Caprolactone-modified dipentaerythritol hexaacrylate (= 2, = 6, = 0 in the structural formula II,
Kayarad DPCA120 manufactured by Nippon Kayaku Co., Ltd. corresponding to = 0 was used. ) 5. Alkyl-modified dipentaerythritol hexaacrylate (Kayarad D-310 manufactured by Nippon Kayaku Co., Ltd. corresponding to = 0, = 5, = 1 in Structural Formula II was used.) 6. Alkyl-modified dipentaerythritol triacrylate Acrylate (Kayarad D-330 manufactured by Nippon Kayaku Co., Ltd. corresponding to = 0, = 3, and = 3 in Structural Formula II was used.) The following C components were used.

7. Hydropivalylaldehyde-modified trimethylolpropane diacrylate (compound of structural formula III, Kayarad R-604 manufactured by Nippon Kayaku Co., Ltd. was used) The following monomers were used.

8. Trimethylolpropane triacrylate (Kayarad TMPTA manufactured by Nippon Kayaku Co., Ltd. was used.

The photopolymerization initiator is 1-hydroxycyclohexyl phenyl ketone (Irgacure 184 manufactured by Ciba-Geigy Co., Ltd.) The solvent is methyl ethyl ketone (abbreviated as MEK) as a typical example.
It was used.

Evaluation method The composition of Table 1 is applied to a paper coated with a water-based ink by a gravure printing machine and dried for 10 seconds by a hot air dryer at 80 ° C. This was cured with a metal halide 80W light bulb of an ultraviolet irradiator, a distance of 10 cm, and a speed of 15 m / min.

Only Experiment No. 12 in Table 1 was cured with an electron beam of 3 Mrad.

The viscosity was judged by the ease of application with a gravure printing machine. The curing speed was determined by the presence or absence of tack on the surface after curing under the above conditions.

The gloss was visually determined after curing.

The hardness was judged by cracking the paper after bending after curing the paper.

Adhesion is rated as ◯ when peeled off with a cellophane tape on the surface after curing and peeled from the underlying paper, and as x when only the coated resin is peeled off, and Δ is in the middle.

The evaluation results are shown in Table-1.

○ is good × is bad △ is between ○ and × (Effect of the invention) By using the active energy ray-curable coating composition of the present invention, it is possible to lower the viscosity and perform high-speed coating, and to cure at a high speed by irradiating ultraviolet rays or electron beams to improve workability Greatly improved. Further, the obtained coating had good adhesion and flexibility, and a product having particularly excellent gloss was obtained.

Claims (1)

[Claims] 1. A. 20-80 parts of a compound of structural formula I (In the formula, the average value of n is 1 to 3.) B. Compound of structural formula II 5 to 50 parts (In the formula, the average value of m is 1 to 3, the average value of a is 0 to 6, the average value of c is 0 to 3, a + b + c = 6.) C. Compound of structural formula III 0 to 40 parts D. Monomers or prepolymers copolymerizable with A, B, C 0
˜40 parts A + B + C + D = 100 parts, on the contrary, E. photopolymerization initiator 0 to 10 parts F. organic solvent 0 to 150 parts, active energy ray-curable coating composition.