JPH111631A - Ultraviolet-curable resin composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a resin composition which, when used as a coating agent for a metallic can coated with a polyester film, can give a coating film excellent in processability, adhesion and lubricity by including a combination of a normally liquid epoxy compound with a phenol/cresol novolac epoxy compound, particles of a resin such as polyethylene and a cationic photopolymerization initiator. SOLUTION: Although the normally liquid epoxy compound may be a known epoxy compound, it is particularly desirably one containing at least 50 wt.% alicyclic epoxy compound by reason of an ultraviolet curing rate. A combination of this with a phenol/cresol novolac epoxy resin of the formula (R is H or CH3 ; and n is 0-6) can improve adhesion in neck processing. The resin particles are ones of a resin (e.g. polyethylene or polytetrafluoroethylene) having a melting point of 90-400 deg.C and are used in an amount of 5-30 pts.wt. per 100 pts.wt. total epoxy compound. The addition of the resin particles can assure the lubricity, overcoatability and printability of a coating film.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resin composition which is cured by irradiation with ultraviolet rays, and particularly as a coating agent for a drawn metal can coated with a polyester film, which has excellent ultraviolet curability, process adhesion and lubricity of a coating film. The present invention relates to an ultraviolet-curable resin composition for a metal can.

[0002]

2. Description of the Related Art Resin compositions which can be cross-linked and cured in a short time by irradiation with ultraviolet light have been used up to now for cationic polymerization compositions using a cationic photopolymerization initiator and an epoxy resin, and for radical photopolymerization initiators and unsaturated A radical polymerization composition using a resin having a heavy bond has been mainly used.

As a cationic polymerization type ultraviolet curable resin composition, studies have been made to use an epoxy resin in combination with other compounds in order to improve the 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
However, these compositions have insufficient UV curability, processing adhesion and lubricity of the coating film for the metal can and the drawn metal can coated with a polyester film of the present invention. is there.

[0004] The coating agent for metal cans and plastic film-coated drawn metal cans is coated on the metal can surface or plastic film-coated drawn metal can surface at a speed of 1500 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 coating process and a Necker flanger process. At this time, if the curability of the coating film is insufficient or the lubricity of the coating film is insufficient, the coating film is damaged or canned, resulting in a significant decrease in production efficiency. In general, to increase the curability of the coating film, it is general to use a monomer having a high curing rate. However, if a monomer having a high curing rate is used, the adhesiveness or workability is reduced. In order to impart lubricity to a coating film, it is generally common to use a silicone compound or wax in combination with a coating material such as a paint. However, in the case of an ultraviolet-curable resin composition, when a silicone compound or wax is used. When it is necessary to provide another coating film or printing layer on the coating film while maintaining the lubricity of the coating film surface, paint or printing ink etc. is repelled due to the lubricity of the coating film surface Problem.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to provide an ultraviolet-curable resin composition which has excellent adhesion to a substrate and provides a coating film having lubricity, coating film hardness and workability. In particular, a coating film having excellent adhesion, lubricity, retort resistance, coating film hardness, and workability, which is suitably used as a coating composition for a base coat of a drawn metal can coated with a plastic film such as a metal can or a polyester film. Another object of the present invention is to provide an ultraviolet-curable resin composition which provides a coating film which does not hinder the lamination of other coating films and ink layers.

[0006]

That is, the first invention is directed to an epoxy compound (A) which is liquid at normal temperature, an epoxy compound (B) represented by the following general formula, polyethylene, polyethylene oxide, polypropylene, polypropylene oxide, polypropylene An ultraviolet curable resin composition comprising at least one resin particle (C) selected from the group consisting of tetrafluoroethylene and a cationic photopolymerization initiator (D).

[0007]

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The second invention is directed to an epoxy compound (A) which is liquid at room temperature and an epoxy compound (B) represented by the above general formula.
And the resin particles (C) in an amount of 5
The ultraviolet-curable resin composition according to the first invention, which is contained in an amount of from 30 to 30 parts by weight.

According to a third aspect of the present invention, there is provided the ultraviolet curable composition according to the first or second aspect, wherein the epoxy compound (A) which is liquid at normal temperature contains at least 50% by weight of an alicyclic epoxy compound. It is a mold resin composition.

A fourth invention is the ultraviolet-curable resin composition according to any one of the first to third inventions, wherein the melting point of the resin particles (C) is 90 to 400 ° C. .

A fifth invention is characterized in that the resin particles (C) are resin particles composed of a mixture of polyethylene and polytetrafluoroethylene, or a mixture of polyethylene resin particles and polytetrafluoroethylene resin particles. An ultraviolet curable resin composition according to any one of the first to fourth inventions.

A sixth invention is the ultraviolet-curable resin composition according to any one of the first to fifth inventions, wherein the composition contains a white pigment (E).

A seventh aspect of the present invention is the ultraviolet curable resin composition according to any one of the first to sixth aspects, wherein the composition is coated with a metal or a metal coated with a plastic film.

An eighth invention is characterized in that a metal can or a drawn metal can coated with a polyester film is coated.
The ultraviolet-curable resin composition according to any one of the inventions to the seventh invention.

A ninth invention is the ultraviolet-curable resin composition according to the eighth invention, which is a coating composition for a base coat for coating a metal can or a drawn metal can coated with a polyester film.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION The epoxy compound (A) which is liquid at ordinary temperature in the present invention is a compound having at least one epoxy group, and a conventionally known alicyclic epoxy compound,
The aliphatic epoxy compound and the aromatic epoxy compound can be used alone or as a mixture, if necessary. However, at least 50% by weight of the alicyclic epoxy compound is contained due to the speed of curing by ultraviolet rays. Is preferred.
As the alicyclic epoxy compound, a compound containing cyclohexene oxide or cyclopentene oxide in its molecular structure is preferably used. Specific examples of the alicyclic epoxy compound are shown below.

[0017]

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[0018]

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[0019]

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[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, and trimethylolpropane triglycidyl ether.

Examples of the aromatic epoxy compound include a bisphenol type epoxy compound.

In the present invention, it is important to use an epoxy compound (B) represented by the following general formula, a so-called phenol / cresol novolac type epoxy resin, in addition to the epoxy compound (A) which is liquid at room temperature. The epoxy compound (A) which is liquid at normal temperature is a monomer having a high curing rate, and a coating film composed of the epoxy compound alone has hardness but has poor adhesion, and the coating film peels off when subjected to neck processing. The epoxy compound (B) represented by the general formula has strong adhesiveness and good neck workability, though the curability is slightly inferior.

[0025]

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In the above general formula, n is a number from 0 to 6. If n is greater than 6, the viscosity of the coating increases, and good coating properties cannot be maintained.

It is generally said that the epoxy compound (B) is inferior in ultraviolet curing property as compared with the alicyclic epoxy compound in the epoxy compound (A) which is liquid at normal temperature. When used together with the epoxy compound (A) which is liquid at room temperature, it shows practically sufficient curability, and the cured coating has stronger adhesion than the coating composed of only the epoxy compound (A) which is liquid at room temperature. It has nature.

As such epoxy resin, phenol novolak epoxy resin manufactured by Asahi Ciba Co., Ltd., Araldite PY307-1, Araldite EPN-117
9, Araldite EPN-1180, Araldite EP
N-1182 and Araldite ECN-1273 and Araldite ECN-
1280 and Araldite ECN-1299. YDPN-638, YDCN
-701, YDCN-702, YDCN-703, YD
CN-704, YDCN-500 and the like. Dow Chemical manufactures DEN-431, DEN-43
8, DEN-439 and the like.

Resin particles (C) used in the present invention
Is at least one selected from the group consisting of polyethylene, polyethylene oxide, polypropylene, polypropylene oxide, and polytetrafluoroethylene, and preferably has a melting point of 90 to 400 ° C. It is considered that by having the melting point in the above range, it is possible to further laminate another coating film or ink layer on the coating film.

After the coating agent of the present invention is coated on a metal can or a drawn metal can coated with a plastic film, it is irradiated with ultraviolet light to form a cured coating film, and is conveyed to the next inner surface coating step or neck processing step. In the case of a base coat, after being irradiated with ultraviolet rays, an ink layer or a top coat layer is provided thereon. 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 productivity. In order to impart lubricity to a coating film, it is common to use a silicone compound or wax in combination with a coating material such as a paint, but in the case of an ultraviolet-curable resin composition, a silicone compound or wax is used. In addition, when it is necessary to provide another coating film or ink layer on the coating film, there is a problem that the paint or ink layer is repelled due to the lubricity of the coating film.

However, the resin particles (C) used in the present invention are 5 to 5 parts by weight based on 100 parts by weight of the total resin.
Even when used at a high concentration of 30 parts by weight, repelling does not occur even if another coating film or ink layer is provided on the coating film.

Although the mechanism has not been elucidated in detail, in the case of a silicone compound or a so-called wax-like lubricant having a low melting point, since it exists on the surface of the coating film as particles or sub-micron particles, It is considered that the space where the ink layer or another coating film is present disappears, and the coating film surface is repelled. The resin particles used in the present invention preferably have a melting point of 90C to 400C. Because the melting point is in the above range, the resin that was present as particles in the coating migrates to the coating film surface when irradiated with ultraviolet light and forms microscopic projections of micron or more to impart lubricity to the coating film. . An ink layer or another paint exists on the surface of the coating film in a place where there are no such microscopic protrusions of microns or more.

The resin particles (C) should be contained in an amount of 5 to 30 parts by weight based on 100 parts by weight of the total of the epoxy compound (A) which is liquid at room temperature and the epoxy compound (B) represented by the above general formula. And more preferably 5 to 15 parts by weight. If the amount is less than 5 parts by weight, the density of the particles becomes small and the lubricity becomes insufficient. If the amount is more than 30 parts by weight, the resin content in the coating film is relatively small, the cohesive force for supporting the particles is reduced, and the coating film is easily damaged.

In the present invention, such resin particles (C) may be used alone, or resin particles composed of a mixture of polyethylene, polyethylene oxide, polypropylene, polypropylene oxide, and polytetrafluoroethylene may be used. Alternatively, a mixture of respective resin particles may be used, and it is preferable to use resin particles composed of a mixture of polyethylene and polytetrafluoroethylene, or a mixture of polyethylene resin particles and polytetrafluoroethylene resin particles. The melting point is 90 ° C-40
As long as the temperature is within the range of 0 ° C., a mixture with other carnauba wax or microcrystalline wax may be used.

As such resin particles, Shamr
Ock's S-394N-1, FS-421, FS
-511, S-232MG, FS-731MG, SST
-3H, NEPTUNE5331, and the like.
PE130, PE190, PE52 by Hoechst
0, PED121, PED153, PED521, PE
D522, PP230 and the like. The products manufactured by Sanyo Kasei Co., Ltd. include Viscol 131-P, Viscol 151-P, Viscol 161-P, Viscol 165-P, and Viscol 171-P. These resin particles may be added to the paint as it is in the form of powder, pellets,
Alternatively, after the granules are heated and melted, a resin particle dispersion formed by dripping the melt into a liquid epoxy compound at room temperature with forced stirring may be added. The cationic photopolymerization initiator (D) used in the present invention includes:
An epoxy compound that releases a substance that initiates cationic polymerization by ultraviolet irradiation, and is a liquid epoxy compound at normal temperature (A)
And 0.5 to 20% by weight, preferably 2 to 1% by weight based on the total weight of the epoxy compound (B) represented by the above general formula.
It is desirable to be compounded within the range of 0% by weight. By blending in this range, adhesion to metal and plastic films, lubricity, retort resistance, coating film hardness,
A cured coating film excellent in processability can be obtained.

As the cationic photopolymerization initiator (D), aryldiazonium salts (for example, P-33 (manufactured by Asahi Denka Kogyo KK)) and aryliodonium salts (for example, FC-5)
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 white pigment (E) used in the present invention
Is mainly used in the case of a base coat, and the sharpness of the printing ink layer can be improved by providing the printing ink layer on the base coat layer having excellent whiteness. As the white pigment, titanium oxide, zinc oxide, zinc sulfide or the like is used. These white pigments can be generally used at any concentration from 20 parts by weight to 150 parts by weight of the resin component.

The ultraviolet-curable resin composition for a metal can of the present invention may contain, if necessary, other conventional components such as organic or inorganic pigments, extender pigments, dyes, organic solvents, and the like, as long as the purpose is not impaired. Coating additives such as auxiliaries, leveling agents, anti-crater agents, surfactants, defoamers, slip agents, UV sensitizers, reactive or non-reactive diluents can be incorporated.

The ultraviolet-curable resin composition of the present invention can be used for substrates such as metal, wood, glass and plastic, but is preferably applied (painted / cured) to metal or plastic film-coated metal. And the metal and the plastic film-coated metal are preferably plate-shaped and can-shaped metal, and plate-shaped and can-shaped plastic film-coated metal. In particular, it is preferably applied (painted / cured) to a drawn metal can coated with a plastic film. The plate shape is
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.

As the metal, steel, aluminum and the like are preferably used, and as the plastic film, a polyester film, a polyolefin film and the like can be mentioned, and a polyester film is preferably used.

The plastic film-coated metal is obtained by laminating a plastic film such as polyethylene terephthalate, polyethylene, polypropylene, nylon, vinyl chloride, vinylidene chloride, or polycarbonate on a metal plate of aluminum or steel. Is a plastic film-coated metal as described above, which is drawn into a cylindrical shape having a capacity of 200 ml to 500 ml, and mainly accommodates food and beverages such as soft drinks, alcoholic beverages, coffee, tea, and soups. Used as a container.

In the case of a drawn metal can coated with a plastic film, it is preferable that the drawn metal can be covered with a polyester film such as polyethylene terephthalate.

The ultraviolet-curable resin composition of the present invention is preferably used for a metal can or a drawn metal can coated with a plastic film as described above. It can also be used on surfaces of plastic films and molded plastics such as polyethylene terephthalate, polyethylene, polypropylene, nylon, vinyl chloride, vinylidene chloride, and polycarbonate.

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

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 ultra-high-pressure mercury lamp, a metal halide lamp, a gallium lamp, xenon Lamps, carbon arc lamps and 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.

[0046]

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, “parts” represents “parts by weight” and “%” represents “% by weight”.

Example 1 80 parts of 3,4-epoxycyclohexylmethyl-3,4 epoxycyclohexylcarboxylate (“Cyracure UVR-6110” manufactured by Union Carbide) 20 parts of phenol novolak epoxy resin (“Araldite EPN1180 manufactured by Asahi Ciba”) 10 parts of polyethylene resin particles ("S232" manufactured by Shamrock) and 5 parts of a cationic photopolymerization initiator ("Siracure UVI-6990" manufactured by Union Carbide) were mixed and stirred to prepare a coating material 1. 3
Substrate obtained by laminating a 100 μm PET film on a 00 μm aluminum plate and a 300 μm thick tin-free steel plate (hereinafter abbreviated as “PET / TFS plate”)
And then passed under a high-pressure mercury lamp of 80 W / cm at a speed of 10 m / min to obtain a cured coating film.

[0047]

[Examples 2 to 5],

Comparative Examples 1 to 4 Examples 2 to 4 were prepared according to the formulation shown in Table 2.
5. The ultraviolet curable compositions of Comparative Examples 1 to 4 were obtained.
A cured coating film was obtained in the same manner as described above.

Table 1 shows the epoxy compounds, resin fine particles, and cationic photopolymerization initiators used in Examples 1 to 5 and Comparative Examples 1 to 4. The repellency of the paints prepared in Examples 1 to 5 and Comparative Examples 1 to 4 and the lubricity, adhesion and retort resistance of the obtained cured coating film were evaluated by the following methods. Table 3 shows the results.

[0049]

【Evaluation methods】

・ Ultraviolet curability The coated plate coated with each coating material was placed on a conveyor whose speed can be changed, passed under a high-pressure mercury lamp of 80 W / cm, and the speed of the conveyor when the tack disappeared after passing was measured.
The practical level is 10 m / min or more.

The lubricating property of the coating film The coated aluminum plate and the “PET / TFS plate” are wound in a cylindrical shape, and the surfaces of the coating film are rubbed under a load of 300 gf until the coating film is damaged. The number of rubs was measured. A practical level is 30 times or more.

-Repellency of coating film Painted aluminum plate and "PET / TFS plate"
0.25 cc of ink (MDKTUQ94 black manufactured by Toyo Ink Mfg. Co., Ltd.) was transferred to the surface of the sample with an RI tester, and a water-based thermosetting type top coat was applied. The ink and the top coat were visually evaluated for cissing. . ：: Number of repelling 0 ○: Number of repelling 2 or less △: Number of repelling 5 or less ×: Number of repelling 6 or more ◎ and ○ are regarded as practical levels.

Adhesion The number of grids where the coating film was not peeled out of 100 grids was measured by a cellophane tape peeling test based on JIS K5400. A level of 90 or more is regarded as a practical level.

-Drawing workability Painted aluminum plate and "PET / TFS plate"
A water-based thermosetting type top coat is applied to the surface of the resin, and a heat-cured coated plate is molded into a cap having a depth of 14 mm, and further subjected to a retort treatment (130 ° C. for 30 minutes) to obtain a peeling height of the coating film. Was measured. The practical level is 10 mm or less.

[0054]

[Table 1]

[0055]

[Table 2]

[0056]

[Table 3]

[0057]

[Table 4]

[0058]

According to the present invention, it is possible to laminate another ink layer or a top coat layer on the coating film, which has a sufficiently practical ultraviolet curing property, and has excellent lubricity and workability. It has become possible to obtain an ultraviolet-curable resin composition that gives a coated film. In particular, when coating a metal can and a drawn metal can coated with a polyester film, a coating film excellent in lubricity, retort resistance and workability can be given as a coating material for an ultraviolet-curable base coat.

Claims (9)

[Claims] 1. At least one selected from the group consisting of an epoxy compound (A) which is liquid at normal temperature, an epoxy compound (B) represented by the following general formula, polyethylene, polyethylene oxide, polypropylene, polypropylene oxide, and polytetrafluoroethylene. An ultraviolet curable resin composition comprising the resin particles (C) and a cationic photopolymerization initiator (D). Embedded image 2. The total amount of the epoxy compound (A) which is liquid at normal temperature and the epoxy compound (B) represented by the above general formula is 1
The ultraviolet-curable resin composition according to claim 1, wherein the resin particles (C) are contained in an amount of 5 to 30 parts by weight based on 00 parts by weight. 3. An epoxy compound (A) which is liquid at normal temperature,
The ultraviolet-curable resin composition according to claim 1, comprising at least 50% by weight of an alicyclic epoxy compound. 4. The resin particles (C) have a melting point of 90 to 400.
The ultraviolet-curable resin composition according to any one of claims 1 to 3, wherein the temperature is ° C. 5. The resin particles according to claim 1, wherein said resin particles (C) are resin particles comprising a mixture of polyethylene and polytetrafluoroethylene, or a mixture of polyethylene resin particles and polytetrafluoroethylene resin particles. 4. The ultraviolet-curable resin composition according to any one of 4. 6. The ultraviolet-curable resin composition according to claim 1, further comprising (E) a white pigment. 7. The ultraviolet-curable resin composition according to claim 1, which is coated with a metal or a metal coated with a plastic film. 8. A metal can or a drawn metal can coated with a polyester film.
The ultraviolet-curable resin composition according to any one of the above. 9. The UV-curable resin composition according to claim 8, which is a coating composition for a base coat for coating a metal can or a drawn metal can coated with a polyester film.