JPH09291132A - Ultraviolet-curing resin composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an ultraviolet-curing resin composition which can give coating films having excellent adhesion to substrates, lubricity, hardness and processability, surface smoothness and transparency by mixing a normally liquid epoxy compound with a specified organopolysiloxane and a cationic photopolymerization initiator. SOLUTION: This composition is prepared by mixing desirably 100 pts.wt. normally liquid epoxy compound (e.g. 3,4-epoxycyclohexylmethyl 3,4- epoxycyclohexylcarboxylate) desirably containing 50wt.% or above alicyclic epoxy compound with desirably 0.05-5 pts.wt. organopolysiloxanes represented by formulas I and/or II (wherein m is 30-90; n is 4-10; x and y are each 10-50; and R is one of OH, OCH3 and OCOCH3 or a combination of two or three of these groups) and desirably 0.5-20wt.%, based on the former two components, cationic polymerization initiator (e.g. arylsulfonium salt).

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a resin composition which is cured by irradiation with ultraviolet rays, and more particularly to an ultraviolet curable resin composition which is preferably used for coating a metal or a plastic film-coated metal. More specifically, as a coating agent for polyester film coated squeezing metal cans,
The present invention relates to an ultraviolet curable resin composition for metal cans, which has excellent adhesion, lubricity, retort resistance, coating film hardness, and workability.

[0002]

2. Description of the Related Art A resin composition capable of being cross-linked and cured in a short time by irradiation with ultraviolet rays is a cationic polymerization composition using a cationic photopolymerization initiator and an epoxy resin, and a radical photopolymerization initiator and an unsaturated dimer. A radical polymerization type composition using a resin having a heavy bond was mainly used.

As a cationic polymerization type ultraviolet curable resin composition, an epoxy resin and another compound have been studied in combination in order to improve physical properties of a cured coating film obtained. UV-curable epoxy silicone / polyol systems (JP-A-3-128975), and UV-initiated cation-curable liquid coating compositions containing an epoxy resin and a polysiloxane having a hydroxyalkyl group (JP-A-59-1984). 2
No. 02264), but when a metal can or a plastic film-coated drawn metal can is coated with these compositions, the surface smoothness, transparency and lubricity of the coating film are insufficient. .

The coating agent for metal cans and plastic film-coated drawn metal cans is applied to the metal can surface or plastic film-coated drawn metal can surface at a speed of 1500 cans or more per minute, and after coating, heated or instantaneously. It becomes a cured coating film by being irradiated with ultraviolet rays. Then, it is conveyed on a guide rail and reaches an inner surface painting process and a Necker flanger process. At this time, if the lubricity of the coating film is insufficient, the coating film is damaged or canned, resulting in a significant decrease in production efficiency. In order to impart lubricity to the coating film, it is common to use a silicone compound in combination with a coating material such as a paint, but in the case of an ultraviolet curable resin composition, there are some problems in using the silicone compound. there were.

That is, in the case of an ultraviolet curable resin composition containing an epoxy compound as a main component which is liquid at room temperature, the elastic modulus of the composition is low, and cissing is likely to occur due to the silicone compound. Further, if the compatibility with the resin is insufficient, the coating film becomes cloudy or the surface of the coating film is not smooth.

When used for a metal can or a plastic film-coated squeezed metal can, the coated metal can is coated with an inner surface paint and baked in the next step, or a necker flanger process is performed in the next step, and then the processed. It may be heat-treated to reduce the distortion of the plastic film. The silicone compound may volatilize due to heat or heat treatment during baking, which may contaminate the inside of the oven.

[0007] Because it cures instantly after being painted,
Convection does not occur in the coating film, and uneven distribution and migration of the silicone compound on the surface hardly occur. Therefore, there is a problem that the lubricity of the coating film surface is difficult to obtain.

[0008]

SUMMARY OF THE INVENTION An object of the present invention is to provide excellent adhesion to a substrate, lubricity, coating film hardness, workability,
Another object of the present invention is to provide an ultraviolet-curable resin composition which gives a transparent coating film having a smooth surface. It has excellent adhesion, lubricity, retort resistance, coating hardness, workability, and is suitable for metal cans and plastic film-coated drawn metal cans such as polyester films, and has a smooth and transparent surface. An object of the present invention is to provide an ultraviolet-curable resin composition that gives a film.

[0009]

That is, the first aspect of the present invention
Of the invention contains an epoxy compound (A) which is liquid at room temperature, an organopolysiloxane (B) represented by the following general formula (1) and / or general formula (2), and a photocationic polymerization initiator (C). The second invention is an epoxy compound (A) which is liquid at room temperature.
Contains at least 50% by weight of an alicyclic epoxy compound, which is the ultraviolet-curable resin composition according to the first invention.

[0010]

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[0011]

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Further, a third invention is based on the general formula (1) with respect to 100 parts by weight of an epoxy compound (A) which is liquid at room temperature.
The organopolysiloxane (B) represented by (2) was added to 0.
05 to 5 parts by weight, the cationic photopolymerization initiator (C) (A)
The ultraviolet curable resin composition according to any one of the first and second inventions, characterized by containing 0.5 to 20% by weight based on the total weight of (B).

A fourth invention is the ultraviolet-curable resin composition according to any one of the first to third inventions, characterized in that a metal or a plastic film-coated metal is coated. It is.

A fifth invention is the ultraviolet-curable resin composition according to the fourth invention, characterized in that the metal is iron or aluminum.

A sixth invention is the ultraviolet-curable resin composition according to the fourth invention or the fifth invention, characterized in that the metal is plate-shaped or can-shaped.

A seventh invention is the ultraviolet curable resin composition according to any one of the fourth to sixth inventions, wherein the plastic film is a polyester film.

The epoxy compound (A) which is liquid at room temperature in the present invention is a compound having at least one epoxy group, and requires a conventionally known alicyclic epoxy compound, aliphatic epoxy compound and aromatic epoxy compound. According to the above, they can be used alone or as a mixture, but it is preferable to contain at least 50% by weight of an alicyclic epoxy compound from the viewpoint of curing speed by ultraviolet rays. As the alicyclic epoxy compound, cyclohexene oxide,
Alternatively, those containing cyclopentene oxide in its molecular structure are preferably used. Specific examples of the alicyclic epoxy compound are given below.

[0018]

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[0019]

[Chemical 6]

[0020]

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[0021]

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Examples of the aliphatic epoxy compound include polyethylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, neopentyl glycol diglycidyl ether, trimethylolpropane triglycidyl ether and the like.

Examples of aromatic epoxy compounds include cresol novolac epoxy resins and bisphenol type epoxy compounds.

The organopolysiloxane (B) used in the present invention is represented by the following general formulas (1) and (2).

[0025]

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[0026]

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In the above general formulas (1) and (2), m is 30.
~ 90. When m is less than 30, when the coating film is heated, the organopolysiloxane is likely to volatilize from the coating film and easily contaminate the inside of the oven. When m is greater than 90, the compatibility with the epoxy compound that is liquid at room temperature becomes insufficient, causing cissing and the coating film becoming cloudy.

In the above general formulas (1) and (2), n is 4 to
It is a number of ten. When n is less than 4, the compatibility becomes insufficient and repelling occurs in the coating film. When n is larger than 10, the coating film has insufficient lubricity.

In the above general formulas (1) and (2), x and y are numbers 10 to 50, respectively. When x and y are smaller than 10, the compatibility becomes insufficient and repelling occurs in the coating film. 5
If it is larger than 0, the lubricity of the coating film will be insufficient.

R in the above general formulas (1) and (2) is O.
It is selected from any one of H, OCH ₃ , and OCOCH ₃ , or a combination of two or three.
When R is OH, compatibility with an epoxy compound that is liquid at room temperature is good and cissing is less likely to occur, but it may be difficult to migrate to the surface of the coating film and lubricity may be poor. It suffices to improve the lubricity by increasing. When R is OCH ₃ or OCOCH ₃ , the organopolysiloxane is unevenly distributed on the surface or near the surface of the coating film immediately after the coating, since the compound has relatively poor compatibility with the epoxy compound which is liquid at normal temperature. Therefore, the lubricity of the coating film is improved. N, x, y when the compatibility with epoxy compounds that are liquid at room temperature is relatively poor and cissing is likely to occur
The repellency may be suppressed by increasing.

Specific examples of the organopolysiloxane (B) represented by the general formulas (1) and (2) include TEGOGLI.
DE410 (manufactured by TEGO Chem Service), DK-Q8
-8598 (50% propylene glycol monomethyl ether solution, manufactured by Dow Corning), DK-Q8-8
550 (50% propylene glycol monomethyl ether solution, Dow Corning) DX-Q8-8169
-4 (manufactured by Dow Corning), DX-Q8-8182
-4 (manufactured by Dow Corning).

The organopolysiloxane (B) represented by the general formulas (1) and (2) is blended in the range of 0.05 to 5 parts by weight with respect to the epoxy compound (A) which is liquid at room temperature. Is desirable. If the amount is less than 0.05 parts by weight,
The coating film has insufficient lubricity, and if it exceeds 5 parts by weight, the compatibility with the epoxy compound becomes poor and cissing may occur.
The coating film may become cloudy.

The photocationic polymerization initiator (C) used in the present invention is an initiator which releases a substance that initiates cationic polymerization upon irradiation with ultraviolet rays, and includes the epoxy compound (A) which is liquid at room temperature and the general formula (1). ) (0) based on the total weight of the organopolysiloxane (B) represented by (2).
It is desirable to be blended in the range of 5 to 20% by weight, preferably 2 to 10% by weight. By blending in this range, adhesion to metal and plastic films,
A cured coating excellent in lubricity, retort resistance, coating hardness, and workability can be obtained.

As the cationic photopolymerization initiator (C), an aryldiazonium salt (for example, P-33 (manufactured by Asahi Denka Co., Ltd.)) and an aryliodonium salt (for example, FC-5) are used.
09 (manufactured by 3M), arylsulfonium salts (Siracure UVI-6974, UVI-6970, UVI-
6990, UVI-6950 (manufactured by Union Carbide), SP-150, SP-170 (manufactured by Asahi Denka Kogyo), allene-ion complex (for example, CG-24-6)
1 (manufactured by Ciba-Geigy) and the like.

The UV-curable resin composition of the present invention may contain other conventional components, if necessary, such as organic or inorganic pigments, extender pigments, dyes, organic solvents, dispersion aids, as long as the purpose is not impaired. Additives for coating such as leveling agents, anti-cratering agents, surfactants, defoaming agents, slip agents, UV sensitizers, reactive or non-reactive diluents can be added.

The ultraviolet-curable resin composition of the present invention can be used as a base material of metal, wood, glass, plastic, etc., but is preferably applied (painted / cured) to metal or plastic film-coated metal. It is preferable that the metal or plastic film-coated metal is a plate-shaped or can-shaped metal or a plate-shaped or can-shaped plastic film-coated metal. In particular, it is preferably applied (painted / cured) to a drawn metal can coated with a plastic film. What is a plate shape?
It may be a relatively short sheet, a relatively long roll, or a flat plate. In addition, the can shape refers to a shape having a cylindrical curved surface regardless of the presence or absence of a bottom and a lid, and irrespective of two pieces or three pieces.

Steel, aluminum, etc. are preferably used as the metal, and polyester film, polyolefin film, etc. are mentioned as the plastic film, and polyester film is preferably used.

The plastic film-covered metal is a metal plate made of aluminum or steel and laminated with a plastic film such as polyethylene terephthalate, polyethylene, polypropylene, nylon, vinyl chloride, vinylidene chloride, or polycarbonate. Is a plastic film coated metal as described above, 200ml ~ 500ml
It is drawn into a cylindrical shape with a capacity of.

In the case of a plastic film-covered drawn metal can, a drawn metal can coated with a polyester film such as polyethylene terephthalate is preferred.

The ultraviolet-curable resin composition of the present invention is preferably used for metal cans and plastic film-coated squeezed metal cans as described above, but in addition to metal cans and plastic film-coated squeezed metal cans, It can also be used on the surfaces of polyethylene terephthalate, plastic films such as polyethylene, polypropylene, nylon, vinyl chloride, vinylidene chloride, and polycarbonate, and plastic molded products.

As the coating method, roll coating, gravure coating, gravure offset coating, curtain flow coating, reverse coating, screen printing, spray coating, dipping and the like are used.

As a light source for photocuring the ultraviolet curable resin composition of the present invention, a light source usually containing light in the range of 200 to 500 nm, for example, a high pressure mercury lamp, an ultrahigh pressure mercury lamp, a metal halide lamp, a gallium lamp, and xenon. A lamp, a carbon arc lamp or the like can be used. It is also possible to use these light sources in combination with heat by infrared rays, far infrared rays, hot air, high-frequency heating, or the like.

[0043]

EXAMPLES The present invention will be described below with reference to examples and comparative examples, but the present invention is not limited to these examples. In the examples, "part" means "part by weight" and "%" means "% by weight". Table 1 shows the average structures of the organopolysiloxanes used in Examples and Comparative Examples.

Example 1 3,4-Epoxycyclohexylmethyl-3,4-epoxycyclohexylcarboxylate 100 parts ("Cyracure UVR-6110" manufactured by Union Carbide) Organopolysiloxane 3 parts (manufactured by Tego Chemiservice) "TEGO.GLIDE410") 5 parts of a cationic photopolymerization initiator ("Cyracure UVI-6990" manufactured by Union Carbide Co., Ltd.) were mixed and stirred to prepare a coating material 1. A material obtained by laminating this coating material on a 300 μm thick aluminum plate and a 300 μm thick tin-free steel plate with a 100 μm PET film (hereinafter abbreviated as “PET / TFS”).
Was coated on a PET film of No. 1 and passed under a high pressure mercury lamp of 80 W / cm at a speed of 10 m / min to obtain a cured coating film.

[0044]

Example 2 Bis- (3,4-epoxycyclohexyl) adipate ("Cyracure UVR-6199" manufactured by Union Carbide) was used as the epoxy compound, and DK-Q8-8598 (manufactured by Dow Corning) was used as the organopolysiloxane. ) Was used to prepare a coating material 2 in the same manner as in Example 1, and a cured coating film was obtained in the same manner as in Example 1.

The epoxy compounds, organopolysiloxanes and photocationic polymerization initiators used in Examples 3 to 5 are shown in Table 2. Table 3 shows the epoxy compounds, organopolysiloxanes, and cationic photopolymerization initiators used in Comparative Examples 1 to 3.

The repellency of the coating materials prepared in Examples 1 to 5 and Comparative Examples 1 to 3 and the lubricity and adhesion of the obtained cured coating films,
The coating film hardness, retort resistance, and volatility of the organopolysiloxane from the cured coating film were evaluated by the methods described below.
The results are shown in Tables 2 and 3.

[0047]

【Evaluation method】

・ Repelling property of the coating film The surface of the coated aluminum plate and PET / TFS plate is visually observed and 100 cm ² (10 cm * 10 cm)
The number of cissing per hit was measured. ◎: Number of cissing 0 ○: Number of cissing 2 or less △: Number of cissing 5 or less ×: Number of cissing 6 or more

Volatility of organopolysiloxane The cured coating film was heated in an oven at 200 ° C. for 10 minutes, and the Si concentration in the coating film before and after heating was measured by a fluorescent X-ray analysis method. Excellent: Si concentration after heating / Si concentration before heating * 10
0 = 100 to 90 Usable: Si concentration after heating / Si concentration before heating * 10
0 = 90-70 Unavailable: Si concentration after heating / Si concentration before heating * 10
0 = 70 or less

Lubricity Surface property measuring device ("HEIDON-14" manufactured by Shinto Scientific Co., Ltd.)
The dynamic friction coefficient was measured at 25 ° C. and 50% RH under the conditions of a load of 200 g, a ball indenter φ of 10 mm, and a moving speed of 100 mm / min.

Adhesion Based on JISK5400, the number of grids where the coating film did not peel off by the cellophane tape peeling test out of 100 grids was displayed.

Coating film hardness Based on JISK5400, the coating film was peeled off at room temperature with a Mitsubishi pencil "Uni", and the maximum hardness that did not reach the base was displayed.

Retort resistance The coated plate was treated in steam at high temperature and high pressure (130 ° C.) for 30 minutes to evaluate whitening and adhesion of the coating film.

[0053]

[Table 1]

[0054]

[Table 2]

[0055]

[Table 3]

[0056]

According to the present invention, the adhesiveness to the substrate is excellent,
It has become possible to obtain an ultraviolet-curable resin composition having lubricity, coating film hardness, workability, and providing a transparent coating film with a smooth surface. Especially when coating metal cans and polyester film coated squeezed metal cans, adhesion,
Not only does it provide a coating with excellent lubricity, retort resistance, coating hardness, workability, surface smoothness, and transparency, but it also reduces the temperature inside the oven due to the volatilization of organopolysiloxane from the coating due to heat in the subsequent process. It has become possible to control and prevent pollution.

Claims (7)

[Claims] 1. An epoxy compound (A) which is liquid at room temperature, an organopolysiloxane (B) represented by the following general formula (1) and / or general formula (2), and a cationic photopolymerization initiator (C). An ultraviolet-curable resin composition for a metal can, which is characterized by: Embedded image Embedded image 2. The epoxy compound (A) which is liquid at room temperature,
2. The ultraviolet-curable resin composition according to claim 1, which contains at least 50% by weight of an alicyclic epoxy compound. 3. An epoxy compound (A) 10 which is liquid at room temperature.
With respect to 0 parts by weight, 0.05 to 5 parts by weight of the organopolysiloxane (B) represented by the general formula (1) and / or the general formula (2), and the photocationic polymerization initiator (C) ( The ultraviolet-curable resin composition according to claim 1 or 2, which contains 0.5 to 20% by weight based on the total weight of A) and (B). 4. The ultraviolet curable resin composition according to claim 1, which is coated with a metal or a metal coated with a plastic film. 5. The ultraviolet curable resin composition according to claim 4, wherein the metal is iron or aluminum. 6. The ultraviolet curable resin composition according to claim 4, wherein the metal is plate-shaped or can-shaped. 7. The ultraviolet curable resin composition according to claim 4, wherein the plastic film is a polyester film.