JPS5971370A - Ultraviolet curing coating composition - Google Patents

Abstract

PURPOSE:The titled composition, prepared by adding a specific peroxide curing catalyst and curing accelerator to an acylic modified eppxy resin based ultraviolet curing coating composition, and curable in a short time into thick films having improved adhesive property and impact resistance, etc. CONSTITUTION:A composition prepared by incorporating an ultraviolet curing coating composition consisting of (A) a main agent component consisting of (i) an acylic modified epoxy resin, (ii) a photopolymerizable monomer, (iii) an extender pgiment and (iv) a thixotropic agent, e.g. silica, and (B) a photosensitizer with (C) 0.1-5.0wt%, based on the above-mentioned component (A), organic peroxide, e.g. tert-butylperoxy 2-ethylhexanoate, lauroyl peroxide and/or decanoyl peroxide, as a curing catalyst, and (D) 0.01-2.0wt%, based on the above-mentioned component (A), one or more of metallic soap, e.g. cobalt naphtenate or manganese naphthenate, and tertiary amines.

Description

[Detailed description of the invention] The present invention relates to a coating composition.

Most conventional photocurable compositions are transparent compositions that simply add a photosensitizer to a photopolymerizable prebolimer and a photopolymerizable monomer. , the photosensitizer absorbs light with a specific wavelength of 2900 to 4500X and generates radicals. A three-dimensional crosslinking reaction occurs between these radicals and the prebolimer and monomer in the photocurable composition, resulting in curing and drying, so unless light passes through the interior 1 of the photocurable composition, the curing reaction will not proceed.

Therefore, transparent or translucent coatings can be photocured, but opaque compositions such as extender pigments or colored pigment-containing compositions have almost no light transmission, and even if only the surface is cured, the interior is not cured. The drawback was that it often hardened.

In order to improve the drawbacks of photocurable coating compositions, Japanese Patent Application No. 57-008000 discloses a main ingredient consisting of a photopolymerizable prepolymer (acrylic modified epochino resin), a photopolymerizable monomer, and a colored pigment. An ultraviolet curable coating composition consisting of an ingredient and a photosensitizer, and a curing catalyst selected from the group consisting of t-butyl baorquine 2-ethylhexanoate, lauroyl peroxide, and decanoyl peroxide for the main ingredient. 01 to 50% by weight of at least one selected organic peroxide.

As hardening accelerators, naphthi/cobalt acid which is a metal soap, mankane naphthenate, naphthi/lead acid and diethylaniline which is a tertiary amine.

Discloses a thick film type ultraviolet curable colored coating composition characterized by containing 0.01 to 20% by weight of at least one compound selected from the group consisting of diethylaniline; A coating film thickness of about 250 to 300 μm has been obtained from a coating composition using the above method. but.

Equipment that requires long-term durability requires a thick film as a heavy-duty anti-corrosion measure.
It is difficult to form a film with a thickness of mm or more, and there are also problems such as the film tends to sag if a thick coating is attempted.

The present inventor has conducted intensive research to develop a thick-film UV-curable coating composition that solves the above-mentioned drawbacks, and has found that the addition of extender pigments and thixotropic agents is effective in preventing sagging. By containing a curing catalyst and a curing accelerator in a material, a composition can be obtained that can be cured in a short time, can form a thick film, and the formed thick film has excellent adhesion and impact resistance. Based on this finding, the present invention has been made.

That is, the present invention provides an ultraviolet curable coating composition comprising a photopolymerizable prepolymer (acrylic modified epoxy resin), a photopolymerizable monomer, an extender pigment, and a thixotropic agent, and a photosensitizer. At least one organic peroxide selected from the group consisting of tx:'chillperoxy 2-ethylhexanoate, lauroyl peroxide, and tecanoyl peroxide is added as a curing catalyst to the main component. % by weight, naphthenic acid salt, a metal soap, as a hardening accelerator.

It was selected from the group consisting of mankanate naphthenate, lead naphthenate, and tertiary amines dimethylaniline and diethylaniline. 0.01 to 2 of at least one compound
The present invention provides a thick film type ultraviolet curable coating composition characterized in that it contains 0% by weight. As the photopolymerizable monomer used in the present invention, methacrylates corresponding to acrylates such as trimethylol protonate acrylate, mono- or polyethylene glycol diacrylate, and 2-hydroquinol acrylate are preferred. Further, as the extender pigment, extender pigments used in ordinary paints, such as Kuruk and mica, can be used. This amount varies depending on the hiding power of the pigment, but if it is 50 parts or less per 100 parts of the resin component, it is possible to form a coating film of 1000 μm or more. +d as a thixotropic agent.

For example, silica, aluminum hydroxide, bentonite, etc. can be used, and the amount thereof is 10 parts or less per 100 parts of the resin component. Furthermore, as a photosensitizer,
Any material used in benzoin alkyl ether may be used, and the amount added is about 01 to 10 parts, preferably about 05 to 5 parts, based on 100 parts of the main ingredient. Suitable curing catalysts used in the present invention include organic peroxides such as t-, i'-tylno-ox-72 ethylhexanoate, lauroyl rhenoki oxide, and decanoyl peroxide.
It is preferable to add 01 to 5 parts per part. If the amount added is small.

If the curing/drying time becomes long or the curing is insufficient, or if the amount added is too large, the curing process will quickly dry out, shortening the pot life and impairing workability, which is unwise.

As a curing accelerator, at least one metal soap such as naphthenic acid conolate or naphthenic acid mankane, and a tertiary amine such as dimethylaniline 7 diethylaniline should be used per 100 parts of the main ingredient. It is preferable to add 0.01 to 10 parts. If the amount added is outside the above range,
Similar problems occur with curing catalysts. The coating composition of the present invention may optionally contain various additives such as color pigments,
Additives used in general paints and inks, such as surfactants, desiccants, and color separation inhibitors, can be added.

It is believed that the ultraviolet curable coating composition of the present invention is cured and dried by the following reaction mechanism. Namely.

■ Photosensitizers on and near the surface of the ruptured membrane absorb ultraviolet light and generate radicals.

■ A part of the generated radicals acts on the curing catalyst and curing accelerator near the surface to promote generation of the radicals.

■ Radical generation by the curing catalyst and curing accelerator continues in a chain even after ultraviolet irradiation has stopped, so radicals are also generated inside the coating.

(2) A radical polymerization reaction between these radicals and the polymerizable double bond groups of the acrylic modified Epoquin resin and the photopolymerizable monomer forms a three-dimensional mesh structure over the entire film, which is cured and dried.

■ In addition, radiant heat from ultraviolet rays and polymerization heat from polymerization reactions also have the effect of promoting radical polymerization reactions.

Therefore, rapid curing and drying is possible even for thick pigment coatings through which ultraviolet rays are difficult to pass.

Next, the effects of the present invention will be listed.

(1) What is the curing mechanism of conventional ultraviolet curable compositions?

Radicals and monomers generated from photosensitizers by absorption of ultraviolet rays that pass through the film.

Because it relies on radical polymerization between prepolymers, it is difficult to cure and dry in cases where ultraviolet rays are difficult to pass through, such as colored coatings. Since a curing catalyst and a curing accelerator are added in addition to a photosensitizer as components, it is possible to rapidly cure even thick pigment coatings that are difficult to transmit ultraviolet rays.

(2) In the case of conventional ultraviolet curable coloring compositions.

Although curing and drying was possible when the thickness of the film was 250 to 300 μm, the composition of the present invention allows the inside of the film to be easily hardened and dried, making it possible to form a thick film of 1000 μm or more.

(3) Regardless of the type of extender pigment, a coating film can be formed satisfactorily as long as the amount of extender pigment is 50 parts or less per 100 parts of the resin component.

(4) By adding 10 parts or less of a thixotropic agent to 100 parts of the resin component, it is possible to prevent the paint from sagging.

(5) A hard coating film with excellent adhesion and impact resistance can be formed.

Next, coatings and coating films made of the ultraviolet curable coating composition of the present invention will be explained in more detail with reference to Examples.

Example 1 Extender pigments were added in Table 1 to a mixture of 50 parts of acrylic modified epoxy resin and 30 parts of triphthylpropane triacrylate.
The mixture was added in the proportion shown in , and kneaded in a ball mill for 16 hours.

Thereafter, 1 part of benzoin isopropyl ether as a photosensitizer, a curing catalyst, a curing accelerator, and a thixotropic agent were added to this mixture in the proportions shown in Table 1 and uniformly dissolved. This is J
I 8-G-8141 cold rolled steel plate (150X70X
8.2 mm) to a film thickness of approximately 250μ, and using one 2kW high-pressure mercury lamp, the irradiation distance was 1.
It was cured by irradiating ultraviolet light at 5 cm.

Table 1 "Na-Co Naphthi/Acid Kame Palt" AN/Methylanili 7 In addition, using an adhesion tester, Ic
The adhesion strength was determined by measuring the peel strength of the coating film having a diameter of n1. In addition, the #] impact resistance of the coating film is IIS-K-540
0-6, 18 method, main P) 500 g,
Measurements were made under the condition of a falling height of 1 m. Weather resistance is J I 8-
Irradiation time 50 by the method of K-5400-6,17
(Measured under 1 hour conditions.As shown in Table 1, by simply adding a small amount of curing catalyst and curing accelerator, even if a large amount of extender pigment is included, the sagging prevention property, curing time, coating film properties, etc.
A composition with very excellent performance in various aspects such as thick film could be obtained.

Example 2 To a mixture of 50 parts of acrylic modified epoxy/resin and 30 parts of monoethylene glycol diacrylate were added 20 parts of talc and 10 parts of mica as extender pigments.

The mixture was kneaded in a ball mill for 16 hours. Thereafter, 1 part of xenzoin methyl ether as a photosensitizer, lauroyl peroxide as a curing catalyst, a curing accelerator, and a thixotropic agent were added to this mixture in the proportions shown in Table 2, and the mixture was uniformly dissolved. This composition was applied in the same manner as in Example 1 and irradiated with ultraviolet rays for 30 seconds.

The coating film performance was measured using the same test method as in Example 1.

Table 2 "Na-Co Cobalt Naphthenate 1" AN / Methyl 7 2 7 As seen from Table 2, the addition of a thixotropic agent had a good sagging prevention effect, and the applied film was easily cured and formed. The physical properties of the coating film were also excellent.

Example 3 A mixture of 50 parts of acrylic modified epoxy/resin, 30 parts of 2-hydroquine acrylate, 15 parts of talc as an extender, and 5 parts of mica, 1 part of benzoin isopropyl ether as a photosensitizer, and a curing catalyst. as decanoyl peroxide 005 to
It was added in the same manner as in Example 1, and exposed to ultraviolet rays at 3.
Irradiation was performed for 0 to 60 seconds. The coating film performance was measured using the same test method as in Example 1.

Table 3 “Na Co Cobalt naphthenate * Bed AN
Dimethylanili/As can be seen from Table 3, if the species modifier (glue force) is added in the range of 5 parts, 0.1 to 5 parts as the curing catalyst, and 0.03 to 20 parts as the curing accelerator, the composition will cure for a long time.

It was found that it has very excellent properties in terms of coating film properties and film thickness.

Example 4 Resin component of Example 2 (mixture of 50 parts of acrylic modified epoxy resin and 30 parts of ethylene glycol diacrylate)
20 parts of talc as an extender pigment.

After adding 10 parts of mica and 5 parts of a seed modifier (noriyoku) and thoroughly kneading, add 1! to this mixture as a photosensitizer. / 1 part of ethyl ether, 3 parts of decanoyl peroxide as a curing catalyst, and 0.5 parts of mankat naphthenate and/or lead naphthenate as a curing accelerator were added, and after uniformly dissolving, the same procedure as in Example 1 was carried out. When applied and irradiated with ultraviolet rays for 30 seconds, a composition with a short curing time and excellent coating properties was obtained.

Example 5 50 parts of acrylic modified epoxy resin, 30 parts of polyethylene glycol diacrylate, 1 part of talc as extender pigment, 20 parts of talc
After kneading in a ball mill a mixture of 1 part of mica, 1 part of mica, and 5 parts of thixotropic agent (gluing force), 1 part of indiyne methyl ether as a photosensitizer and 0 part of t-butylperoquine 2-ethylhexanoate as a curing catalyst. A composition prepared by adding cobalt naphthenate and/or diethylaniline as a curing accelerator at a ratio of 0.001 to 10 parts and uniformly dissolving the mixture was applied in the same manner as in Example 1, and exposed to ultraviolet light at 20 parts. ~6
When irradiated for 0 seconds, it was found that the curing time was short and the coating film had excellent properties when the curing catalyst was added in an amount of 0.1 to 5 parts and the curing accelerator was added in an amount of 0.01 to 0.5 parts.

Comparative Example Example 1.2 and Example 3 (Nl 12. Depth 3. Spacing 4)
When coating without adding a seed modifier (gluing force) in the formulation described above, all of the coatings were prone to sagging, resulting in an uneven film thickness of 300 μm or less, and a uniform thick film could not be obtained.

As described above in detail, the ultraviolet curable coating composition of the present invention allows the species modifier to be used even when it contains an extender pigment that is difficult to cure and dry in conventional photocurable coating compositions. When used in combination, it is possible to apply thick coatings without sagging, and the curing is completed in a few seconds to several tens of seconds, and thick films can be formed without containing volatile components.
It has many advantages such as high impact resistance.

As described above, the present invention provides a photocurable coating composition that is industrially very useful.

Claims (1)

[Claims] Acrylic modified epoxy/resin, photopolymerizable monomer. An ultraviolet curable coating composition consisting of a main component consisting of an extender pigment and a thixotropic agent, and a photosensitizer, and t-butyl peroquino 2-ethylhexanoate and lauroyl as a curing catalyst for the nine main components. Cobalt naphthenate, which is a metal soap, contains 01 to 50% by weight of at least one peroxide selected from the group consisting of peroxide and tecanoyl peroxide as a curing accelerator. It was selected from the group consisting of mankanate naphthenate, lead naphthenate, and the tertiary amines dimethylaniline and diethylaniline. At least one compound from 001 to 20
An original model ultraviolet curable coating composition characterized in that it contains an extremely high percentage by weight.