JP3409648B2 - UV curable resin composition - Google Patents

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 polyester film-coated squeezed metal cans, which is excellent in ultraviolet curability, processing adhesion and coating film lubricity. The present invention relates to an ultraviolet curable resin composition for metal cans.

[0002]

2. Description of the Related Art A resin composition which is crosslinked and cured in a short time by irradiation with ultraviolet rays has hitherto been known as a cationic polymerization composition using a cationic photopolymerization initiator and an epoxy resin, and a radical photopolymerization initiator and an unsaturated dicarboxylic acid. A radical polymerization type composition using a resin having a heavy bond was mainly used.

As a cationic polymerization type ultraviolet curable resin composition, in order to improve the physical properties of the cured coating film obtained, it has been studied to use an epoxy resin in combination with other compounds, for example, a silicone composition in the composition. UV-curable epoxy silicone / polyol system (JP-A-3-128975), UV-initiated cationically curable liquid coating composition containing epoxy resin and polysiloxane having hydroxyalkyl group (JP-A-59- Two
No. 02264), but these compositions have insufficient ultraviolet curability, process adhesion and coating film lubricity for metal cans and polyester film-coated drawn metal cans of the present invention. is there.

A coating agent for a metal can or a plastic film-coated squeezed metal can is applied to the surface of the metal can or the plastic film-coated squeezed metal can at a speed of 1500 cans per minute or more, and after coating, it is heated or instantly. It becomes a cured coating film when it is irradiated with ultraviolet rays. After that, it is transported on the guide rails to reach the inner surface coating process and the necker flanger process. At that time, if the curability of the coating film is insufficient or the lubricity of the coating film is insufficient, the coating film may be scratched or canned and the production efficiency may be significantly reduced. In order to improve the curability of the coating film, it is general to use a monomer having a fast curing rate, but if a monomer having a fast curing rate is used, the adhesiveness is lowered and the processability is lowered. In order to impart lubricity to the 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, when using the silicone compound or wax While maintaining the lubricity of the coating film surface, and when it is necessary to provide another coating film or printing layer on the coating film, paint or printing ink is repelled due to the lubricity of the coating film surface. There is a problem that it ends up.

[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 gives a coating film having lubricity, coating film hardness and processability. Particularly, it is a coating film having excellent adhesion, lubricity, retort resistance, coating film hardness, and processability, which is preferably used as a base coat coating composition for metal cans, polyester film, and other plastic film-coated drawn metal cans. In addition, it is an object of the present invention to provide an ultraviolet curable resin composition that provides a coating film that does not hinder the lamination of other coating films and ink layers.

[0006]

That is, the first invention is to provide an epoxy compound (A) which is liquid at room temperature, an epoxy compound (B) represented by the following general formula, polyethylene, polyethylene oxide, polypropylene, polypropylene oxide, poly An ultraviolet curable resin composition comprising at least one kind of resin particles (C) selected from the group consisting of tetrafluoroethylene and a photocationic polymerization initiator (D).

[0007]

[Chemical 2]

A second invention is an epoxy compound (A) which is liquid at room temperature and an epoxy compound (B) represented by the above general formula.
And the total amount of 100 parts by weight of the resin particles (C) is 5
The ultraviolet-curable resin composition according to the first invention is characterized by containing 30 to 30 parts by weight.

A third invention is characterized in that the epoxy compound (A), which is liquid at room temperature, contains at least 50% by weight of an alicyclic epoxy compound, so that the ultraviolet curing as described in the first invention or the second invention. Type 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 aspect of the 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. The 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, characterized in that it contains a white pigment (E).

A seventh invention is the ultraviolet-curable resin composition according to any one of the first to sixth inventions, which is characterized by coating a metal or a metal coated with a plastic film.

An eighth invention is characterized in that a metal can or a polyester film-coated drawn metal can is coated.
The ultraviolet-curable resin composition according to any one of the inventions to 7th inventions.

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 polyester film-coated drawn metal can.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION The epoxy compound (A) which is liquid at room temperature in the present invention is a compound having at least one epoxy group, which is a conventionally known alicyclic epoxy compound,
An aliphatic epoxy compound and an aromatic epoxy compound can be used alone or in combination, if necessary, but at least 50% by weight of an alicyclic epoxy compound is contained because of the rapid curing property by ultraviolet rays. Is preferred.
As the alicyclic epoxy compound, those containing cyclohexene oxide or cyclopentene oxide in its molecular structure are preferably used. Specific examples of the alicyclic epoxy compound are given below.

[0017]

[Chemical 3]

[0018]

[Chemical 4]

[0019]

[Chemical 5]

[0020]

[Chemical 6]

[0021]

[Chemical 7]

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 bisphenol type epoxy compounds.

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 room temperature, is a monomer having a fast curing rate, and a coating film composed only of this has a high hardness, but has poor adhesion, and peeling occurs in the coating film when subjected to neck processing. Although the epoxy compound (B) represented by the general formula has a slightly inferior curability, it has strong adhesion and good neck processability.

[0025]

[Chemical 8]

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

It is said that the epoxy compound (B) is generally inferior in ultraviolet curability to the alicyclic epoxy compound in the epoxy compound (A) which is liquid at room temperature. When used in combination with an epoxy compound (A) that is liquid at room temperature, it exhibits practically sufficient curability, and the cured coating film has stronger adhesion than a coating film that is composed only of the epoxy compound (A) that is liquid at room temperature. Have sex.

Examples of such epoxy resin include phenol novolac epoxy resin manufactured by Asahi Ciba Co., Ltd., Araldite EPN-1179, Araldite EPN-118.
0, Araldite EPN-1182, and cresol novolac epoxy resin, Araldite ECN-1273,
Araldite ECN-1280, Araldite ECN-
1299 and the like. YDC manufactured by Tohto Kasei
N-701, YDCN-702, YDCN-703, Y
Examples thereof include DCN-704 and YDCN-500.
DEN-431, DEN-43 manufactured by Dow Chemical Company
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 setting the melting point within the above range, it is possible to further laminate another coating film or an ink layer on the coating film.

After the coating agent of the present invention is coated on a metal can or a plastic film-coated drawn metal can, it is irradiated with ultraviolet rays to form a cured coating film, which 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 and a top coat layer are provided thereon. At this time, if the lubricity of the coating film is insufficient, the coating film may be scratched or canned, resulting in a marked decrease in productivity. In order to impart lubricity to the 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. When it is necessary to provide another coating film or ink layer on the coating film, there is a problem that the coating material or the 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 of the total resin content.
Even when used at a high concentration of 30 parts by weight, repellency does not occur even if another coating film or ink layer is provided on the coating film.

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

These resin particles (C) should be contained in an amount of 5 to 30 parts by weight per 100 parts by weight of the total amount of the epoxy compound (A) which is liquid at room temperature and the epoxy compound (B) represented by the above general formula. Is preferable, and it is preferable to further contain 5 to 15 parts by weight. If it is 5 parts by weight or less, the density of the particles becomes small and the lubricity becomes insufficient. When the amount is 30 parts by weight or more, 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 scratched.

In the present invention, each of the 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 made of a mixture of polyethylene and polytetrafluoroethylene, or a mixture of polyethylene resin particles and polytetrafluoroethylene resin particles. The melting point is 90 ° C to 40 ° C.
A mixture with other carnauba wax or microcrystalline wax may be used as long as it is within the range of 0 ° C.

Such resin particles include Shamr
S-394N-1, FS-421, FS
-511, S-232MG, FS-731MG, SST
-3H, NEPTUNE 5331, and the like.
PE130, PE190, PE52 manufactured by Hoechst
0, PED121, PED153, PED521, PE
Examples include D522 and PP230. Sanyo Chemical Co., Ltd. includes Viscole 131-P, Viscole 151-P, Viscole 161-P, Viscole 165-P, Viscole 171-P and the like. These resin particles may be powdered and added to the paint as they are, pellets,
Alternatively, the resin particle dispersion formed by dropping the melted liquid while forcibly stirring may be added to the epoxy compound which is liquid at room temperature after heating and melting the granular one. The cationic photopolymerization initiator (D) used in the present invention is
Epoxy compound (A), which is an initiator that releases a substance that initiates cationic polymerization upon irradiation with ultraviolet rays and is liquid at room temperature
And 0.5 to 20% by weight, preferably 2 to 1 based on the total weight of the epoxy compound (B) represented by the above general formula.
It is desirable that the compounding amount be within the range of 0% by weight. By blending in this range, adhesion to metal and plastic films, lubricity, retort resistance, coating hardness,
A cured coating film having excellent workability can be obtained.

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

White pigment (E) used in the present invention
Is mainly used in the case of a base coat, and by providing a printing ink layer on a base coat layer having excellent whiteness, the sharpness of the printing ink layer can be improved. As the white pigment, titanium oxide, zinc oxide, zinc sulfide or the like is used. Generally, these white pigments can be used in any concentration from 20 parts by weight to 150 parts by weight of the resin component.

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

The UV-curable resin composition of the present invention can be used for a substrate such as metal, wood, glass, plastic, etc., but is preferably applied (painted / cured) to a metal or a plastic film-coated metal. It is preferable that the metal or the 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 plastic film-covered drawn metal can. What is a plate shape?
It may be a relatively short sheet, a relatively long roll, or a flat plate. Further, the can-like shape means a shape having a cylindrical curved surface regardless of whether a bottom or a lid is present, or whether it is a two-piece or a three-piece.

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 drawn into a cylindrical shape with a capacity of 200 ml to 500 ml, and mainly contains beverages and drinks such as soft drinks, alcoholic drinks, coffee, tea and soup. Used as a container.

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

The UV-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 photo-curing 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, xenon is used. A lamp, a carbon arc lamp or the like can be used. Further, it is possible to use these light sources in combination with heat from 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 thereto. In the examples, "part" means "part by weight" and "%" means "% by weight".

Example 1 3,4-Epoxycyclohexylmethyl-3,4 epoxy cyclohexyl carboxylate 80 parts ("Cyracure UVR-6110" manufactured by Union Carbide) Phenol novolac epoxy resin 20 parts ("Araldite EPN1180 manufactured by Asahi Ciba") 10 parts of polyethylene resin particles (“S232” manufactured by Shamrock) 5 parts of photocationic polymerization initiator (“Syracure UVI-6990” manufactured by Union Carbide) were mixed and stirred to prepare a coating material 1. This coating material was thick. 3
Base material 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”).
Was coated on a PET film of No. 1 and passed through 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 2 according to the formulations shown in Table-2
5, the ultraviolet curable compositions of Comparative Examples 1 to 4 were obtained, and Example 1
A cured coating film was obtained in the same manner as in.

Table 1 shows the epoxy compounds, resin fine particles and photocationic polymerization initiator used in Examples 1 to 5 and Comparative Examples 1 to 4. The repellency of the coating materials prepared in Examples 1 to 5 and Comparative Examples 1 to 4 and the lubricity, adhesion, and retort resistance of the obtained cured coating films were evaluated by the methods described below. The results are shown in Table-3.

[0049]

【Evaluation methods】

-A coating plate coated with each UV-curable 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 the passage was measured.
A practical level is set to 10 m / min or more.

Lubricity of coating film A coated aluminum plate and "PET / TFS plate" are wound in a cylindrical shape, a coating of 300 gf is rubbed against each other, and the coating surfaces are rubbed until scratches occur on the coating film. The number of rubbing was measured. The practical level is 30 times or more.

・ Aluminum plate with cissing property of coating film, and "PET / TFS plate"
0.25 cc of ink (MDKTUQ94 black ink manufactured by Toyo Ink Mfg. Co., Ltd.) was transferred to the surface of the ink using an RI tester, and a water-based thermosetting top coat was applied to visually evaluate the cissing of the ink and the top coat. . ⊚: Number of repellents 0 ○: Number of repellents 2 or less Δ: Number of repellents 5 or less ×: Number of repellents 6 or more ◎ and ○ are practical levels.

Adhesion Based on JIS K5400, the number of crosses where the coating film did not peel off was displayed by the cellophane tape peeling test out of 100 crosses. 90 or more is set as a practical level.

· Painted aluminum plate and "PET / TFS plate"
The surface of is coated with a water-based thermosetting top coat and thermoset, molded into a cap with a depth of 14 mm, and then subjected to retort processing (130 ° C-30 minutes) to remove 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]

EFFECTS OF THE INVENTION According to the present invention, it has a sufficiently practical ultraviolet curability, and another ink layer or a top coat layer can be laminated on the coating film, which is excellent in lubricity and processability. It has become possible to obtain an ultraviolet-curable resin composition that gives a coating film. In particular, when coating a metal can or a polyester film-coated drawn metal can, a coating film having excellent lubricity, retort resistance, and processability can be provided as an ultraviolet-curable base coat paint.

─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP 62-275172 (JP, A) JP 55-157664 (JP, A) JP 9-40760 (JP, A) JP 7- 179511 (JP, A) JP 58-217516 (JP, A) JP 5-125150 (JP, A) JP 8-143755 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) C08G 59/00-59/72 C09D 163/00-163/10 C08L 63/00-63/10

Claims (9)

(57) [Claims] 1. At least one selected from the group consisting of an epoxy compound (A) which is liquid at room temperature, an epoxy compound (B) represented by the following general formula, polyethylene, polyethylene oxide, polypropylene, polypropylene oxide, and polytetrafluoroethylene. An ultraviolet-curable resin composition containing the resin particles (C) and the cationic photopolymerization initiator (D). [Chemical 1] 2. The total amount of the epoxy compound (A) which is liquid at room temperature and the epoxy compound (B) represented by the above general formula 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 with respect to 00 parts by weight. 3. The epoxy compound (A) which is liquid at room temperature,
The ultraviolet-curable resin composition according to claim 1 or 2, which contains at least 50% by weight of an alicyclic epoxy compound. 4. The melting point of the resin particles (C) is 90 to 400.
4. The ultraviolet curable resin composition according to any one of claims 1 to 3, which is at a temperature of 0 ° C. 5. The resin particles (C) are resin particles made of 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 above. 6. The ultraviolet curable resin composition according to claim 1, which contains a white pigment (E). 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 polyester film-coated drawn metal can is coated.
The ultraviolet curable resin composition according to any one of claims. 9. The ultraviolet curable resin composition according to claim 8, which is a coating composition for a base coat for coating a metal can or a polyester film-coated drawn metal can.