JPS62236867A - Method for curing photo-curable resin paint composition - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a method for curing a photocurable resin coating composition with excellent adhesion and processability. The present invention relates to an effective method for curing a coating composition comprising a photocurable resin composition and a photocurable resin composition.

(Prior Art and its Problems) A large number of printing inks and coating compositions that are cured by light, particularly ultraviolet light, are known, and their usefulness is already well known.

However, there are still many unresolved problems, one of which is the problem of processability.

The photocurable resin composition has a high ability to form a crosslinkable film, and therefore provides a film having desirable properties such as high hardness, excellent solvent resistance, and stain resistance. However, on the other hand, it tends to become a brittle film, In particular, adhesion and workability to metals are often poor.

To improve processability, long-chain oligomers are often used to reduce the degree of crosslinking of the effect film and increase its flexibility, but in this case, surface hardness, solvent resistance, etc. It is difficult to obtain sufficient adhesion and processability even at the expense of physical properties.

As a result of intensive research to solve the above-mentioned problems, the inventors of Wooden et al. discovered that a coating composition in which a thermosetting resin composition and a thermosetting resin composition were mixed in a specific ratio was cured using a specific curing method.
That is, in the first step, primary curing is performed using thermal energy such as infrared irradiation or a hot air oven, and in the second step, curing is performed by light irradiation such as ultraviolet rays, which improves adhesion and processability to various metal substrates. The present invention was completed based on the finding that a film with excellent hardness, solvent resistance, and flexibility can be obtained.

(Means for solving the problem) That is, the present invention provides a thermosetting resin composition (A) and a photocurable resin composition (B) in which the solid content weight ratio of A:B is 95=
5 to 20: A method for curing a photocurable resin coating composition, which comprises applying a coating composition obtained by blending the coating composition to 80 on a substrate, heating it, and then irradiating it with light. be.

To explain the present invention in detail, the thermosetting resin composition (A) used in the present invention includes amino-alkyd resin clear paint, maleated rosin-modified alkyd resin paint, phenolic resin-modified alkyd resin paint, and epoxy-modified alkyd resin. There are paints and the like, and particularly preferred are amino-oil-free alkyd clear paints in which oil-free alkyd is blended with butyl etherified melamine, butyl etherified benzoguanamine, etc.

These paints are preferably transparent paints, which are crosslinked and cured by heating with thermal energy such as infrared rays or hot air ovens, and desirably have no reactivity with the photocurable resin coexisting therein.

Further, the photocurable resin composition (B) to be blended into the thermosetting resin composition is a known material, and is composed of a photocurable resin and a photopolymerization initiator as main components. It consists of additives, pigments, dyes, solvents, etc. added as necessary.

Typical examples of photocurable resins include relatively low molecular weight polyester resins that have radically polymerizable unsaturated double bonds in their molecular structures, polyether resins, acrylic resins, epoxy resins, urethane resins, and alkyd resins. , oligomers such as acrylates and methacrylates of polyfunctional compounds such as polyhydric alcohols, and monofunctional monomers such as ethyl acrylate, ethylhexyl acrylate, styrene, methylstyrene, and N-vinylpyrrolidone as reactive diluents; Contains functional monomers such as trimethylolpropane triacrylate, hexanediol diacrylate, diethylene glycol diacrylate, dipentaerythritol hexaacrylate, neopentyl glycol diacrylate, etc., and these components may be used alone or in mixtures. used as.

In the present invention, it is desirable to use the above-mentioned polyfunctional oligomer so that it accounts for 70% (weight) or more of the photocurable resin.

The photopolymerization initiator is a compound that generates free radicals from the energy of light, especially ultraviolet light, and includes benzoin, benzophenone, acetophenone, derivatives such as esters thereof, and thioxanthone derivatives. Can be used in combination.

However, organic peroxides such as benzoyl peroxide, and those that easily generate radicals due to heat, such as azobisisobutyronitrile, are not preferred. Note that when an electron beam is used as light energy, a photopolymerization initiator is not necessary.

Furthermore, various additives such as silicones, waxes, paint suitability regulators, dyes, pigments, etc. can be used in the photocurable resin as necessary.

The blending ratio of the thermosetting resin composition (A) and the photocurable resin composition (B) in the present invention is 95=5 to 2 by weight.
If the B component is less than 5, the effect of improving the physical properties of the film by the photocurable resin is small, and the surface hardness and solvent resistance are poor.

In addition, if the B component exceeds 80, it is not preferable because processability decreases due to poor adhesion and decreased flexibility.

In the present invention, heat treatment is performed before ultraviolet irradiation, but any heat treatment may be used as such heat treatment, and a preferred method is a method of irradiating infrared rays. It is preferable to generate infrared rays having a wavelength of 2 to 20 gm. The amount of infrared rays irradiated is sufficient to make the coating tack-free to the touch. Although it depends on the output of far infrared rays, irradiation for about 10 seconds to 2 minutes is sufficient. Also,
When using a hot air stove instead of infrared rays, the temperature and humidity should be 140 to 2.
00° C., and the heating time is about 2 minutes to 20 minutes.

In addition, light irradiation performed after the heat treatment, for example, ultraviolet irradiation, can be performed using a high-pressure mercury lamp with an output of 80 to 160 W/cm or a high-pressure mercury lamp with an output of 8
It is desirable to use a high output lamp such as a metal halide lamp with a power output of about 0 to 160 W/cm. The irradiation time depends on the conditions, but about 1 to 30 seconds is sufficient.

The present invention will be specifically explained below with reference to Reference Examples and Examples. In the text, parts and percentages are based on weight unless otherwise specified.

Reference Example 1 Preparation of Thermosetting Resin Composition (A) Oil-free alkyd resin 125 parts (60% solution of Kijilor butyl cellosolve) 33 parts of butyl etherified benzoguanamine resin (60% solution of Kijilor butanol) Epoxy resin (trade name Epon 1001, Shell product) 30
part (MIBK/Kijirol 30% solution) Silicone 0.1 part P-1 Luenesulfonic acid 0.2 part Each component was stirred with a disilver to obtain a thermosetting resin composition (A).

Reference Example 2 Preparation of photocurable resin composition (B) Polyester acrylate 40 parts Urethane acrylate 40 parts Epoxy acrylate 20 parts Phosphoric acid acrylate
4 part benzophenone
2 parts 2.2'-dimethoxy-2-phenylacetophenone 2 parts silicon
0.1 part solvent (30 parts toluene,
A mixture consisting of 20 parts of butyl acetate, 20 parts of ethyl cellosolve and 30 parts of isopropyl alcohol)
50 parts of the above components were stirred and dissolved in a disilver to obtain a photocurable resin composition (B).

Example 1 Thermosetting resin composition (A) of Reference Example 1 100 parts urethane acrylate 20 parts dipentaerythritol hexaacrylate 10 parts jetoxyacetophenone 0.7 parts 2-hydroxy-2-methyl-1-phenonylpropane -1-one 0.7 parts The above components were uniformly mixed and dissolved to obtain a coating composition with a viscosity of 40 seconds (Iwata Cup, 20°C).

The above coating composition was coated on a printed aluminum plate using a bar coater so that the dry film thickness was 8 to 10 ILm, dried with hot air at 60°C for 1 minute, and then heated with a far infrared heater (2KW/30cm x 30cm, Distance! 20cm
) for 60 seconds. Furthermore, a high pressure mercury lamp (160W/c
m, height 15 cm) and passed once at a conveyor speed of 3 W/min to obtain a cured film. The physical properties of the obtained film are shown in Table 1.

Example 2 90 parts of the thermosetting resin composition (A) of Reference Example 1; 90 parts of the photocurable resin composition (B) of Reference Example 2;
20° C.) was obtained.

This coating composition was applied to a printed steel plate using a bar coater to form a film in the same manner as in Example 1.

The physical properties of the obtained film are shown in Table 1.

Comparative Example 1 For comparison, the thermosetting resin composition prepared in Reference Example 1 (
A) was applied to a printed aluminum plate and cured under heat to form a film in the same manner as in Example 1.

The physical properties of the obtained film are shown in Table 1.

Comparative Example 2 The photocurable resin composition (B) prepared in Reference Example 2 was applied to a printing steel plate and cured to form a film in the same manner as in Example 1.

The physical properties of the obtained film are shown in Table 1.

``LJ kesa example'' LJ kesa example'' Length aim ヱ control lid 5 (removal of cellophane tape, 1mm x 100)
1 month late 10pm 1107p starvation hardening 3H3H mc methyl ethyl ketone rubbing 50 times) No abnormality
No abnormality ball f 7 mm 7 mm Comparative example 1
Le Comparison Weekly Supervision 5 (Peeling cellophane tape, 1mm x 100)
w 10ILm 10pm red! Violet! F 4H Salmonosis Tongo (Methyl Ethyl Ketone Rubbing 50 times) Defective Elution 10 times without abnormality) 34 7!1111 7mm crack (Function/Effect) In the curing method of the present invention, the first stage of curing is thermal curing using thermal energy. By separating the curing of the thermosetting resin and the second stage of photocuring, a film is formed that shares the adhesion and workability of the thermosetting resin and the hardness and solvent resistance of the photocuring resin.

Therefore, as is clear from the results in Table 1, according to the method of the present invention, a coating with good hardness, adhesion, workability, and solvent resistance can be provided on a substrate such as a printed steel plate. .

1 construction Procedural amendment (voluntary) December 24, 1986

Claims (1)

[Claims] (1) The thermosetting resin composition (A) and the photocurable resin composition (B) have a solid content weight ratio of A:B of 95:5 to 20:
A method for curing a photocurable resin coating composition, which comprises applying a coating composition obtained by blending the coating composition to a coating composition of 80% and 80% on a substrate, heating the coating composition, and then irradiating the coating composition with light.