JPH10230212A - Coated structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a coating film from a damage such as peeling by applying a coating material containing resin particulates in a specified wt.% so that a part of the particulates may be embedded in the coating film and remainder may be projected from a surface of the coating film, and curing the coating material by ultraviolet ray. SOLUTION: 2-10wt.% Resin particulates are incorporated in the ultraviolet curing type coating material. Then a part of the particulates is embedded in the coating film and remainder is allowed to protrude from the surface of the coating film and cured by the ultraviolet ray. An average grain size of the resin particulates is kept in 5-15μm, and a smooth part of the cured coating film is kept in 0.5-1 time thickness of the average grain size of the resin particulates. For example, a resin other than resin particulates, reactive diluent, oligomer and monomer are blended and dissolved. Moreover, lubricants, an initiator, sensitizer, titanium oxide and 2-10wt.% resin particulates are added to produce the ultraviolet curing type coating material. The coating film having a coefficient of dynamic friction of about 0.10 is obtained in the case when the coating material is applied and cured by ultraviolet ray and the peeling is prevented and a resistance to scuffing is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coating structure using an ultraviolet-curable paint, and more particularly to a coating structure having improved scratch resistance.

[0002]

2. Description of the Related Art A coating composition containing an ultraviolet-curable resin is:
During drying or baking, there is no problem of evaporation of the solvent,
Since it does not require heating of the painted material, it is actually used for various applications and its use is being studied.

[0003] Conventionally, as an ultraviolet curable resin composition,
A combination of an epoxy resin and a cationic ultraviolet polymerization initiator, a combination of a urethane (meth) acrylate and a (meth) acrylate monomer, and an epoxy (meth) acrylate resin are known.

JP-A-96-7344 discloses a resin comprising an ultraviolet-curable resin composition comprising an aliphatic cyclic epoxy resin, a cationic polymerization initiator and a polydiorganosiloxane-polyoxyalkylene alternating block copolymer. A composition is described.

[0005]

The ultraviolet-curable resin composition has an advantage that a cured coating film can be formed by irradiating ultraviolet rays without the need for heating. There is still a drawback in the scratch resistance, and there is a drawback that the coating film is easily peeled or scratched due to contact or rubbing with another object such as a conveying member.

For example, ultraviolet curable resins have begun to be used as a coating layer or a printing ink layer for packaging containers such as seamless cans. In packaging containers, not only during the manufacturing process but also during the filling process, the containers are used. A smooth transport operation is indispensable, and if the outer coating layer or the printing ink layer has low slipperiness, the coating is easily damaged by contact or collision with another object. Further, in order to improve the preservability of the contents, hot filling, pasteurizer sterilization operation, retort sterilization, and the like are performed, but in these steps, there is a problem that the coating film is damaged.

[0007] As seen from the above-mentioned proposals, the method of blending silicones, animal and plant waxes, etc., with an ultraviolet-curable paint is effective in imparting lubricity, but is not effective when the paint is pressed against other paints. Rubbing on an object causes peeling or cracking of the coating film, and it has not yet been achieved to eliminate the scratch resistance peculiar to the ultraviolet curable coating.

Accordingly, an object of the present invention is to provide a coating structure of an ultraviolet-curable paint having excellent scratch resistance, especially peeling or cracking even when the ultraviolet-cured coating is rubbed against another object in a pressed state. It is an object of the present invention to provide a painted structure, in particular, a painted packaging container, which does not cause the occurrence of cracks. Another object of the present invention is to provide a coating structure of an ultraviolet-curable paint that has excellent scratch resistance and excellent transportability even when the ultraviolet-curable paint is provided with a considerably thin thickness on the substrate surface. To offer.

[0009]

According to the present invention, an ultraviolet-curable paint containing 2 to 10% by weight of resin fine particles is provided.
The coating is applied to a substrate and cured with ultraviolet light so that a part of the resin fine particles is embedded in the coating film and another part protrudes from the smooth surface of the coating film, and is characterized by being scratch-resistant. Thus, a painted structure excellent in quality is provided. In the painted structure of the present invention, 1. The resin fine particles have an average particle size of 5 to 15 μm, and the smooth portion of the cured coating film has a thickness of 0.5 to 1 times the average particle size of the resin fine particles. 2. the resin fine particles have a hardness smaller than the hardness of the coating film matrix; 3. The resin fine particles have a glass transition point (Tg) of room temperature or lower; 4. The ultraviolet-curable paint contains a lubricant that is liquid at a temperature of 50 ° C. or less; 5. The ultraviolet-curable paint contains 30 to 50% by weight of fine particles of titanium oxide; 6. The resin fine particle-containing cured coating film has a dynamic friction coefficient of 0.2 or less; 7. the base is a metal can; Preferably, the substrate is a metal plate for a can.

[0010]

DETAILED DESCRIPTION OF THE INVENTION

[Action] In the present invention, (A) the UV-curable paint contains 2 to 10% by weight of resin fine particles, and (B)
It is characterized in that a part of the resin fine particles is embedded in the coating film, and the other part is applied to the substrate and cured with ultraviolet rays so as to protrude from the smooth surface of the coating film. The scratch resistance of the film can be significantly improved. 2. The coating film obtained by curing the ultraviolet-curable coating material can reduce the kinetic friction coefficient of the coating film to about 0.12 by blending a normal lubricant, but when subjected to the transport scratch resistance test, Scratches occur significantly (see Comparative Example 1 described later). On the other hand, when the resin fine particles are blended in an ultraviolet-curable paint and ultraviolet-cured, the occurrence of scratches is eliminated in the transport scratch resistance test (see Example 1). 3. First, in the UV-curable paint, the resin is cured without heating, so that the resin fine particles can be present in the coating film while maintaining the particle structure.
This is the same even when the resin fine particles have a low softening point. 4. In the present invention, coating and ultraviolet curing are performed so that a part of the resin fine particles protrude from the smooth surface of the coating film. In FIG. 1 for explaining this state, the base 1
Is composed of a laminate of tin-free steel (TFS) 2 and polyethylene terephthalate (PET) film 3, and has an ultraviolet-curable coating 4 on the PET film.
Is given. The UV-curable paint contains resin fine particles 5, which are exposed outside the coating film surface 6. When the coating film is rubbed due to the lubricity of the exposed resin fine particles 5, The scratching property of is eliminated. That is, it is recognized that the resin fine particles 5 act to prevent direct contact between another object and the cured coating film surface 6 and reduce friction with the object due to its own lubricity. . Actually, when the surface of the coating film after ultraviolet curing is observed with an electron microscope, it is confirmed that resin fine particles are distributed in an island shape in the sea of the ultraviolet curing coating film (FIG. 2). 5. In the present invention, it is also important that the resin fine particles are contained in the UV-curable coating at 2 to 10% by weight. When the content of the resin fine particles is less than the above range, a scratch is generated in the transport scratch resistance test (see Comparative Example 4).
On the other hand, when the content of the resin fine particles exceeds the above range, the coatability is reduced, and it becomes difficult to form a coating film having a good appearance, and peeling of the coating film occurs even in the transport scratch resistance test. (See Comparative Example 5). That is, there is an optimum density range of the distribution of the sea-island structure described above for the improvement of the scratch resistance, and the scratch resistance can be improved at the above-mentioned ratio. 6. In addition, it is important that coating and UV curing are performed so that a part of the resin fine particles protrude from the smooth surface of the coating film. It becomes possible by adjusting the thickness of the part. In the present invention, the resin fine particles preferably have an average particle size of 5 to 15 μm, and the smooth portion of the cured coating film preferably has a thickness of 0.5 to 1 times the average particle size of the resin fine particles. 7. If the thickness of the cured coating film is smaller than the above range, the damage in the transport scratch resistance test tends to increase (see Comparative Example 2). This is presumably because if the thickness of the ultraviolet-cured coating film is too small compared to the particle size of the resin fine particles, anchoring of the resin fine particles to the coating film is insufficient, and the resin fine particles fall off. On the other hand, if the thickness of the cured coating film is larger than the above range, the damage in the transport scratch resistance test also tends to increase (see Comparative Example 3). This is thought to be because if the thickness of the ultraviolet-cured coating film is too large compared to the particle size of the resin fine particles, the resin fine particles will be buried in the coating film and the sea-island structure will not be sufficiently developed. 8. Although the resin fine particles used in the present invention have lubricity, the resin fine particles preferably have a hardness smaller than the hardness of the coating film matrix, and have a glass transition point (Tg) of room temperature or lower. It is preferable to have one. If the hardness of the resin fine particles is higher than that of the coating film matrix, peeling of the coating film tends to occur at the time of the transport scratch resistance test (see Comparative Example 7). Is improved. In other words, it is believed that when the resin fine particles satisfy the above conditions, the impact when contacting the object is absorbed by the resin fine particles, thereby preventing damage to the coating film. 9. In the coating structure of the present invention, the resin fine particle-containing cured coating film preferably has a dynamic friction coefficient of 0.2 or less. For this reason, the ultraviolet curable coating material is a lubricant which is liquid at a temperature of 50 ° C. or less. It is desirable to contain
That is, the lubricant which is a liquid at a temperature of 50 ° C. or lower becomes a liquid state due to an increase in the temperature of the coating film at the time of ultraviolet curing, and spreads evenly on the coating film, so that the effect of improving lubricity is great. When the kinetic friction coefficient of the cured coating film is out of the above range, there is a tendency that the coating film is damaged during the transport scratch resistance test (see Comparative Example 6). 10. The effect of improving the scratch resistance of the coating structure of the present invention is particularly remarkable when the filling amount of the pigment is high, particularly when the UV-curable coating contains 30 to 50% by weight of titanium oxide fine particles. . Since pigments such as titanium dioxide absorb short-wavelength ultraviolet rays, ultraviolet curing may be insufficient in some cases. However, according to the present invention, scratch resistance can be improved also in this case.

[Resin Fine Particles] In the present invention, the resin fine particles to be blended with the ultraviolet-curable paint have lubricity, and include olefin-based resins, acrylic resins, and fluorine-based resins.

Particularly preferred resin fine particles are olefin resin particles, such as low-, medium- or high-density polyethylene, isotactic polypropylene, syndiotactic polypropylene, linear low-density polyethylene, and ethylene-propylene. Polymer, polybutene-1,
Ethylene-butene-1 copolymer, propylene-butene-
Fine particles such as 1 copolymer, ethylene-propylene-butene-1 copolymer, ethylene-vinyl acetate copolymer, ion-crosslinked olefin copolymer (ionomer), and ethylene-acrylate copolymer are used.

These olefin resins have a glass transition point lower than room temperature, and are particularly excellent in scratch resistance of the ultraviolet-cured coating film. The molecular weight of the olefin-based resin is not particularly limited, but those having relatively low molecular weights generally called polyethylene wax and polypropylene wax give excellent effects. Oxidized polyethylene wax,
Modified olefin resins such as acid-modified polyethylene wax are also suitably used for the purpose of the present invention.

Another preferable example of the resin fine particles is acrylic resin fine particles having a glass transition point lower than room temperature. Examples of the acrylic monomer constituting the acrylic resin include methyl (meth) acrylate, ethyl (meth) acrylate, isopropyl (meth) acrylate, n-butyl (meth) acrylate, and (meth) acrylate.
Isobutyl acrylate, n-amyl (meth) acrylate, isoamyl (meth) acrylate, n-hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, n-octyl (meth) acrylate, etc. Can be. However, the above (meth) acrylic acid means acrylic acid or methacrylic acid. These acrylic monomers may optionally contain other comonomers, such as styrene,
It may be copolymerized with acrylic acid, methacrylic acid, maleic anhydride, divinylbenzene, ethylene glycol dimethacrylate, and the like.

In order to keep the glass transition point of the acrylic resin low, the content of methyl (meth) acrylate in the acrylic resin is preferably not more than 50% by weight, and in order to give flexibility to the acrylic resin, It is also effective to copolymerize (meth) acrylate having a long-chain alkyl group having 4 or more carbon atoms in an amount of 20 to 70% by weight.

It is also effective to introduce a crosslinked structure into the acrylic resin particles in order to prevent the acrylic resin from dissolving in the ultraviolet-curable paint. The monomers are copolymerized.

Other examples of the resin fine particles include fluorine resins such as polytetrafluoroethylene, tetrafluoroethylene / hexafluoropropylene copolymer, polyvinyl fluoride, and polyvinylidene fluoride. Although these fluororesins have a glass transition point higher than room temperature, their excellent slip properties contribute to scratch resistance.

These resin fine particles are generally 4 to 15
The average particle diameter (volume-based median diameter) of μm, especially 5 to 14 μm is preferred. The particle shape of the resin fine particles is preferably spherical, but is not necessarily limited to this.
Irregular particles obtained by a pulverization method or the like, or other irregular particles may be used.

The density of the fine resin particles is generally preferably in the range of 0.8 to 2.5 g / cm ³ , the particle size of the fine resin particles is relatively small even in the above range, and the resin is cured by ultraviolet light. When the thickness of the mold paint is in a relatively large range, it is recommended to use relatively light resin fine particles having a density of 0.8 to 1.0 g / cm ³ .

[Ultraviolet curable paint] In the present invention, an ultraviolet curable paint is used as the paint. In this paint,
It contains an ultraviolet curable resin and a catalyst, and is roughly classified into a cationic curable type and a radical polymerizable type.
The present invention shows excellent effects on any of these paint systems.

(1) Cation-Curable Coating A combination of an ultraviolet-curing epoxy resin and a photo-cationic polymerization catalyst is used as the UV-cationic polymerization coating.

The UV-curable epoxy resin includes an epoxy resin component having an alicyclic group in the molecule and an adjacent carbon atom of the alicyclic group forming an oxirane ring. For example, an epoxy compound having at least one epoxycycloalkane group, for example, an epoxycyclohexane ring, an epoxycyclopentane ring, or the like is used alone or in combination.

Suitable examples include, but are not limited to,
Vinylcyclohexene diepoxide, vinylcyclohexene monoepoxide, 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexane carboxylate, 2- (3,4-epoxycyclohexyl-5,
5-spiro-3,4-epoxy) cyclohexane-m-
Dioxane, bis (3,4-epoxycyclohexyl)
Adipate, limonenedoxide, and the like.

The cationic ultraviolet polymerization initiator used in combination with the above epoxy resin is one which is decomposed by ultraviolet rays to release a Lewis acid, and this Lewis acid has an action of polymerizing an epoxy group. An aromatic iodonium salt, an aromatic sulfonium salt, an aromatic selenium salt, an aromatic diazonium salt and the like can be mentioned.

The diallyliodonium salts include, for example, diphenyliodonium hexafluoroantimonate, diphenyliodonium hexaolophosphate, 4-chlorophenyliodonium tetrafluoroborate, di (4-methoxyphenyl) iodonium chloride, (4-methoxyphenyl) phenyl And iodonium.

Examples of the triarylsulfonium salt include, for example, triphenylsulfonium tetrafluoroborate, triphenylsulfonium hexafluorophosphate, p- (phenylthio) phenyldiphenylsulfonium hexafluoroantimonate, triphenylsulfonium hexafluoroantimonate, and 4-chloroamine Phenyldiphenylsulfonium hexafluorophosphate and the like.

Examples of the triarylselenium salt include triphenylselenium hexafluorophosphate, triphenylselenium hexafluoroantimonate and the like.

As other cationic polymerization initiators,
(2,4-cyclopentagen-1-yl) [(1-methoxythiethyl) -benzene] -iron-hexafluorophosphate, diphenylsulfonium hexafluoroantimonate, dialkylphenylsulfonium hexafluoroantimonate, dialkylphenylsulfonium Hexafluorophosphate, 4,4'-bis [di (β-hydroxyethoxy) phenylsulfonio]
Phenylsulfide-bis-hexafluoroantimonate, 4,4-bis [di (β-hydroxyethoxy) phenylsulfonio] phenylsulfide-bis-hexafluorophosphate and the like can be mentioned.

The cationically curable coating composition may contain a known diluent, another epoxy resin, a sensitizer, a crosslinking agent, and the like.

As the diluent, phenyl glycidyl ether, methylphenyl glycidyl ether, n-butyl glycidyl ether, 1,2-epoxyhexadecane,
Examples thereof include vinyl ethers, oxetane compounds, and polyhydric alcohol derivatives containing one hydroxyl group.

As another epoxy resin for modification, a bisphenol-type epoxy resin derived from bisphenols such as bisphenol A and bisphenol F and epichlorohydrin is used.

As sensitizers, thioxanthone derivatives,
Examples include 2,4-diethylthioxanthone and 2,4-diisopropylthioxanthone.

Examples of the crosslinking agent include various polyols such as ε-caprolactone triol.

A suitable example of a cationically curable paint formulation is:
Although not limited thereto, 1 to 10 parts by weight of the cationic ultraviolet initiator per 100 parts by weight of the alicyclic epoxy resin,
Particularly 2 to 8 parts by weight, diluent 1 to 10 parts by weight, especially 1
To 5 parts by weight, 1 to 20 parts by weight of another epoxy resin, especially 2 to 10 parts by weight, 0.1 to 2 parts by weight of a sensitizer, especially 0.2 to 1.5 parts by weight, and 1 to 20 parts by weight of a crosslinking agent Department,
In particular, it is composed of 2 to 10 parts by weight.

(2) Ultraviolet Radical Curable Paint As the ultraviolet radical polymerizable paint, a combination of an ultraviolet curable monomer or prepolymer and a photopolymerization catalyst is used.

As the UV-curable monomer or prepolymer, a monomer or prepolymer having a plurality of ethylenically unsaturated groups in a molecule or a mixture thereof is used. Suitable examples include epoxy acrylate resin, urethane acrylate resin, thermosetting acrylic resin, thermosetting polyester resin and the like.

As the epoxy acrylate resin, an adduct of a bisphenol-type epoxy resin with an ethylenically unsaturated carboxylic acid, for example, acrylic acid or methacrylic acid, or an adduct of this with an ethylenically unsaturated polycarboxylic acid anhydride, for example, A reaction product with maleic anhydride, itaconic anhydride or the like is used.

As the urethane acrylate resin, a urethane acrylate resin obtained by reacting an isocyanate-terminated polyester or an isocyanate-terminated polyol with a functional group-containing acrylic monomer such as acrylic acid, methacrylic acid, hydroxyethyl (meth) acrylate, etc. Is used.

Examples of the thermosetting acrylic resin include 1,6-hexanediol diacrylate (HDDA), 1,6-hexanediol dimethacrylate (HDDMA), neopentyl glycol diacrylate, neopentyl glycol dimethacrylate, and ethylene glycol diacrylate. Acrylate (EGD
A), ethylene glycol dimethacrylate (EGDMA), polyethylene glycol diacrylate (PEGMA-A), polyethylene glycol diacrylate (PEGMA), polypropylene glycol diacrylate, polypropylene glycol dimethacrylate, butylene glycol diacrylate, butylene glycol dimethacrylate, pentane Erythritol diacrylate, 1,4-butanediol diacrylate, trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, pentaerythritol triacrylate, dipentaerythritol hexaacrylate, tetramethylolmethanetetraacrylate, N, N, N ', N '-Tetrakis (β-
An acrylate of hydroxyethyl) ethylenediamine, 2,2-bis [4- (3-methacryloyloxy-2-hydroxypropoxy) phenyl) propane and the like are used.

Examples of the thermosetting polyester resin include polyesters containing an ethylenically unsaturated bond in the molecule, for example, ethylenically unsaturated polycarboxylic acids such as maleic acid, fumaric acid, itaconic acid and tetrahydrophthalic acid. , Isophthalic acid, trimellitic acid, pyromellitic acid, adipic acid, sebacic acid, combinations with other acid components such as polymerized fatty acids, and ethylene glycol, diethylene glycol, propylene glycol, glycerin, neopentyl glycol, trimethylolpropane, pentane Polyester resins obtained by condensation with polyhydric alcohols such as erythritol and bisphenols are used.

The above-mentioned polyfunctional monomers or prepolymers are usually used in combination with monofunctional monomers. Examples of such monomers include acryloyl morpholine, glycidyl acrylate (GA), glycidyl methacrylate (GMA). ), Carbitol acrylate,
Tetrahydrofurfuryl acrylate, tetrahydrofurfuryl methacrylate, dicyclopentadienyl acrylate, dihydrodicyclopentadienyl methacrylate, isobornyl acrylate, acrylamide (AA
m), methacrylamide (MAm), N-methylolacrylamide (N-MAM), N-diacetoneacrylamide (DAA
M), N-vinylpyrrolidone, maleic acid, itaconic acid,
Methyl methacrylate (MMA), ethyl acrylate (E
A), styrene (ST), acrylonitrile (AN), vinyl acetate
(VAc), vinyl toluene (VT), etc.

Further, divinylbenzene, diallyl phthalate (DAP), diallyl isophthalate, diallyl adipate, diallyl glycolate, diallyl maleate, diallyl sebacate, triallyl phosphate,
Other polyfunctional monomers such as triallyl aconitate, allyl trimellitate, allyl pyromellitic acid and the like may also be used.

Representative examples of the photoradical initiator include benzoin such as benzoin, benzoin methyl ether, benzoin ethyl ether and benzoin isopropyl ether and alkyl ethers thereof; acetophenone, 2,2-dimethoxy-2-phenylacetophenone, 2,2-diethoxy-2-phenylacetophenone, 1,1-dichloroacetophenone, 1-hydroxycyclohexylphenyl ketone, 2-hydroxycyclohexylphenyl ketone, 2-methyl-1- [4- (methylthio) phenyl] -2-morpholino -Propane-
Acetophenones such as 1-one; anthraquinones such as 2-methylanthraquinone and 2-amylanthraquinone; 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, 2-chlorothioxanthone, and 2,4
Thioxanthones such as diisopropylthioxanthone, ketals such as acetophenone dimethyl ketal and benzyl dimethyl ketal; benzophenones such as benzophenone or xanthones; bis (2,6-dimethoxybenzoyl) -2,4,4-trimethylpentylphosphine oxide And phosphine oxides such as 2,4,6-trimethylbenzoyldiphenylphosphine oxide.

Such a photo-radical initiator can be used in combination with one or more known and known photo-polymerization accelerators such as benzoic acid or tertiary amine.

In the radical-curing coating, the photo-radical initiator is used in an amount of 0.1 to 30 parts by weight per 100 parts by weight of the ultraviolet-curable resin.
It is preferably used in a proportion of 1 part by weight, preferably 1 to 25 parts by weight.

(3) Pigment The ultraviolet-curable coating material used in the present invention contains a coloring pigment or an extender. Suitable examples of pigments are as follows. Black pigments Carbon black, acetylene black, run black, aniline black. Yellow pigment Yellow lead, zinc yellow, cadmium yellow, yellow iron oxide, mineral fast yellow, nickel titanium yellow, navels yellow, naphthol yellow S, Hanza yellow G, Hanza yellow 10G, benzidine yellow G,
Benzidine Yellow GR, Quinoline Yellow Lake, Permanent Yellow NCG, Tartrazine Lake. Orange pigments Red mouth lead, molybdenum orange, permanent orange GTR, pyrazolone orange, Vulcan orange, induslen brilliant orange RK, benzidine orange G, induslen brilliant orange GK. Red pigment Bengala, cadmium red, lead red, cadmium mercury sulfide, permanent red 4R, lithol red, pyrazolone red, watching red calcium salt, lake red D, brilliant carmine 6B, eosin lake, rhodamine lake B, alizarin lake, brilliant carmine 3B. Purple pigment Manganese purple, fast violet B, methyl violet lake. Blue pigment Navy blue, cobalt blue, alkali blue lake, Victoria blue lake, phthalocyanine blue, metal-free phthalocyanine blue, partially chlorinated phthalocyanine blue, first sky blue, indaslen blue B
C. Green pigment chrome green, chromium oxide, pigment green B,
Malachite Green Lake, Fanal Yellow Green G. White pigments zinc white, titanium dioxide, antimony white, zinc sulfide. Extender barite powder, barium carbonate, clay, silica, white carbon, talc, alumina white.

These pigments are generally used in an amount of from 10 to 55% by weight per paint.

For use as a white coating of a packaging container or a lid, it is preferable to contain titanium dioxide in the above amount. Titanium dioxide absorbs ultraviolet light having a shorter wavelength, so that ultraviolet curing may be insufficient in some cases. However, according to the present invention, scratch resistance can be improved also in this case.

(4) Lubricants It is preferable that the cured coating film containing fine resin particles has a dynamic friction coefficient of 0.2 or less. For this reason, lubricants which are liquid at a temperature of 50 ° C. or less for ultraviolet-curable paints are preferred. Is contained. Examples of the lubricant include animal and vegetable fats and oils such as palm oil, coconut oil and camellia oil, lanolins, and silicone resins. The lubricant is used in an amount of 0.1 g per UV-curable paint.
It may be used in an amount of 2 to 4% by weight.

The UV-curable paint may contain other compounding agents, for example, silicone oil or the like as an antifoaming agent, a fluorine-based surfactant, a silicone-based surfactant, or an acrylic copolymer as a leveling agent. For example, a thickener, a thickener, and the like can be used.

Further, the ultraviolet-curable resin composition includes:
A plasticizer for imparting flexibility or flexibility to the film can be contained. Examples of the plasticizer include phthalate ester plasticizers, adipate ester plasticizers, ester plasticizers such as succinate ester plasticizers, polyester plasticizers, phosphate ester plasticizers, and chlorine plasticizers. Can be These plasticizers are preferably used in an amount of 15 parts by weight or less, particularly 1 to 10 parts by weight, per 100 parts by weight of the resin composition.

Since the ultraviolet-curable resin composition used in the present invention exhibits remarkable non-Newtonian behavior, it is difficult to define its viscosity. However, in general, the apparent viscosity at a shear rate of 1 sec ^{-1 has} an apparent viscosity of 1 to 5000 poise (p, p). (20 ° C.).

[Substrate of Coating Structure] The substrate on which the ultraviolet-curable coating material is provided can be any material, for example, any molded product such as metal, plastic, ceramic, glass, and wood. Among these molded articles, the present invention is useful for coating various packaging containers, particularly packaging containers formed of metal, plastic, or a laminate thereof. For example, the container may be a can made of a metal material or a coated metal material, a bottle made of a thermoplastic resin, a cup, a pouch, a tube made of a thermoplastic resin laminate or a thermoplastic resin metal foil laminate. In particular, it is useful as a finishing varnish for cans, cups, bottles, pouches, tubes, etc., which can be subjected to heat sterilization such as retort sterilization, printing ink, undercoat, topcoat layer and the like. Hereinafter, an example thereof will be described.

(1) Cans for Cans Examples of cans for cans include seamless cans formed by drawing / deep drawing or drawing / ironing of a metal material or a resin-coated metal material. A laminate obtained by laminating a thermoplastic resin film such as polyester on the surface of a metal substrate and subjecting the laminate to deep drawing or draw-ironing has attracted attention as having excellent corrosion resistance and workability. Although this polyester coating layer is excellent in mechanical properties and barrier properties against corrosive components, it has poor adhesion to white coats, printing inks or finishing varnishes, and cans after applying these coats, inks or varnishes When the body is subjected to neck-in processing, bead processing, or the like, there has been a problem that the coat, ink and varnish are easily peeled off.

On the other hand, when the coating material of the present invention is applied in the form of a white coat or the like on the polyester coating layer of the above-mentioned can body and is subjected to ultraviolet curing, good transportability during processing is maintained. Needless to say, even after severe neck-in processing and bead processing, there is no damage such as peeling, and even if retort sterilization is performed after filling and sealing the contents, excellent adhesion state is maintained It is possible to increase the commercial value.

As the metal plate constituting the can, various surface-treated steel plates and light metal plates such as aluminum are used. As a surface-treated steel sheet, cold-rolled steel sheet is subjected to secondary cold rolling after annealing,
One or more kinds of surface treatments such as zinc plating, tin plating, nickel plating, electrolytic chromic acid treatment, and chromic acid treatment can be used. An example of a suitable surface-treated steel sheet is an electrolytic chromic acid-treated steel sheet, particularly a metal chromium layer of 10 to 200 mg / m ² and 1 to 50 mg / m 2.
² (in terms of metal chromium) and a chromium oxide layer, which is excellent in combination of coating film adhesion and corrosion resistance. Other examples of surface-treated steel sheets are 0.5 to 1
It is a hard tin plate having a tin plating amount of 1.2 g / m ² . This tin plate has a chromium content of 1 in terms of metal chrome.
It is desirable that chromic acid treatment or chromic acid / phosphoric acid treatment be performed so as to be 30 to 30 mg / m ² . As still another example, an aluminum-coated steel sheet subjected to aluminum plating, aluminum pressure welding, or the like is used. Among these, the effect is particularly large when applied to the above-mentioned electrolytic chromic acid-treated steel sheet.

On the other hand, as the light metal plate, an aluminum alloy plate is used in addition to a so-called pure aluminum plate. Aluminum alloy plate which is excellent in terms of corrosion resistance and workability is Mn:
0.2 to 1.5% by weight, Mg: 0.8 to 5% by weight,
Zn: 0.25 to 0.3% by weight, and Cu: 0.15
To 0.25% by weight, with the balance being Al. It is desirable that these light metal plates have also been subjected to a chromic acid treatment or a chromic / phosphoric acid treatment such that the chromium amount becomes 20 to 300 mg / m ^{2 in} terms of chromium metal.

Thickness of metal plate, ie thickness of can bottom (tB)
Although it varies depending on the type of metal, the use or size of the container, it is generally good to have a thickness of 0.10 to 0.50 mm. Among them, in the case of a surface-treated steel sheet,
It is preferable to have a thickness of 0.10 to 0.30 mm, and in the case of a light metal plate, a thickness of 0.15 to 0.40 mm.

As the thermoplastic resin coated on the metal plate, a crystalline thermoplastic resin is preferable. Examples of the thermoplastic resin include polyethylene, polypropylene, ethylene-propylene copolymer, ethylene-vinyl acetate copolymer and ethylene. Olefin resin films such as acrylic ester copolymers and ionomers; polyethylene terephthalate;
Polyesters such as polybutylene terephthalate and ethylene terephthalate / isophthalate copolymer; polyamides such as nylon 6, nylon 6,6, nylon 11 and nylon 12; polyvinyl chloride; polyvinylidene chloride;

The coating of the coated thermoplastic resin on the metal plate is carried out by a heat fusion method, dry lamination, extrusion coating method or the like, and the adhesiveness between the coated resin and the metal plate (heat fusion property).
When the content is insufficient, for example, a urethane-based adhesive, an epoxy-based adhesive, an acid-modified olefin resin-based adhesive, a copolyamide-based adhesive, a copolyester-based adhesive, or the like can be interposed.

The thickness of the thermoplastic resin is generally 3 to 50.
μm, especially in the range of 5 to 40 μm. In the case of heat fusion using a film, it may be unstretched or stretched.

As a particularly suitable film, a polyester mainly composed of ethylene terephthalate units is formed into a film by a T-die method or an inflation film forming method, and the film is biaxially stretched sequentially or simultaneously at a stretching temperature. A film produced by heat-setting the subsequent film can be mentioned.

As a raw material polyester, polyethylene terephthalate itself can be used under the conditions of stretching, heat setting and laminating, which are extremely limited. However, lowering the maximum crystallinity that can be achieved by the film requires impact resistance and workability. For this purpose, it is preferable to introduce a copolymer ester unit other than ethylene terephthalate into the polyester for this purpose. It is particularly preferable to use a biaxially stretched film of a copolymerized polyester mainly composed of ethylene terephthalate units and containing a small amount of other ester units and having a melting point of 210 to 252 ° C. The melting point of homopolyethylene terephthalate is generally from 255 to 265 ° C.

The copolyester used should have a molecular weight sufficient to form a film, for which the intrinsic viscosity (IV) is between 0.55 and 1.9 dl / g, in particular between 0.65 and 1.4 dl / g. Those in the range of g are desirable.

The adhesive primer optionally provided between the polyester film and the metal material exhibits excellent adhesiveness to both the metal material and the film. A typical primer paint excellent in adhesion and corrosion resistance is a phenol epoxy paint composed of a resol type phenol aldehyde resin derived from various phenols and formaldehyde, and a bisphenol type epoxy resin, Particularly, a phenol resin and an epoxy resin are mixed in a ratio of 50: 5
0 to 5:95 weight ratio, especially 40:60 to 10:90
Is a paint contained in a weight ratio of

The adhesive primer layer generally has a thickness of 0.3 to 5
The thickness is preferably set to μm. The adhesive primer layer may be provided in advance on a metal material or may be provided in advance on a polyester film.

Forming into a metal cup-shaped container is carried out by means known per se so as to reduce the thickness of the side wall, such as drawing redrawing and ironing, drawing bending and redrawing, drawing bending and redrawing and redrawing and ironing. Done in

For example, according to the deep drawing bending and elongation forming (drawing-bending and elongation redrawing), a front drawing cup formed from a coated metal plate is placed on an annular holding member inserted into the cup and underneath. Hold with the redrawing die located. A redrawing punch is arranged coaxially with the holding member and the redrawing die so as to be able to enter and exit the holding member. The redrawing punch and the redrawing die are relatively moved so as to mesh with each other.

As a result, the side wall of the front drawing cup extends from the outer peripheral surface of the annular holding member through its curvature corner,
The front drawing cup is bent vertically inward, passes through a portion defined by the annular bottom surface of the annular holding member and the upper surface of the redrawing die, and is bent almost vertically in the axial direction by the working corner of the redrawing die. It can be formed into a deep drawing cup having a smaller diameter than that of the deep drawing cup.

At this time, the radius of curvature (Rd) of the working corner of the redrawing die is set to 1 to 2.9 times, particularly 1.5 to 2.9 times the thickness (tB) of the metal plate. This makes it possible to effectively reduce the thickness of the side wall portion by bending and tension. In addition, the variation in the thickness between the lower portion and the upper portion of the side wall portion is eliminated, and uniform thickness reduction can be achieved over the whole. Generally, the side wall of the can body is In the formula, tB is the thickness of the base plate, and tW is the thickness of the side wall portion. The thinning rate can be reduced to 5 to 45%, particularly 5 to 40%.

For a deep drawn can, the following formula In the formula, D is the diameter of the sheared laminate material, and d is the punch diameter.
To 3.0, and preferably 1.5 to 5.0 in total.

Further, an ironing die is arranged at the rear of the redrawing or bending and redrawing, and the thinning rate including the ironing is 5 to 70%, particularly 10 to 60% with respect to the side wall.
And can be thinned by ironing.

(2) Plastic Packaging Containers Examples of suitable plastic packaging containers include bottles, cups, tubes, plastic cans, pouches, caps, and the like.

The molding of the plastic into a container can be performed using an extruder or an injection machine. As the extruder, an extruder provided with an arbitrary screw is suitably used. As the die, a flat die or a ring die can be used. For example, a T-die method or an inflation film forming method is used for forming a film. Also, by hollow-forming the extruded parison, a hollow-molded container such as a bottle, a tube, and a tank is formed.

As the injection machine, a known injection machine having an injection plunger or a screw is used, and the plastic is injected into an injection mold through a nozzle, a sprue, and a gate. As a result, the resin flows into the injection mold cavity and is cooled and solidified to form a molding container or a preform for stretch blow molding.

As the plastic constituting the container, olefin resin, polyester resin, polyamide resin, polycarbonate and the like are preferably used. .

As the olefin resin, low-, medium- or high-density polyethylene (LDPE, MDPE, HD
PE), isotactic polypropylene (PP),
Linear low density polyethylene (LLDPE), ethylene-propylene copolymer, polybutene-1, ethylene-butene-1 copolymer, propylene-butene-1 copolymer, ethylene-propylene-butene-1 copolymer, ethylene -Vinyl acetate copolymers, ionically crosslinked olefin copolymers (ionomers), ethylene-acrylate copolymers, and blends thereof. The coating can be applied to a resin having a low melting point such as linear low-density polyethylene.

As the polyester, polyethylene terephthalate (PET), polybutylene terephthalate,
Polyethylene naphthalate, ethylene terephthalate /
Examples thereof include polyesters such as isophthalate copolymers and blends thereof.

On the other hand, polyamides such as nylon 6
(N6), nylon 6,6 (N6,6) nylon 11,
Examples thereof include polyamides such as nylon 12, copolymer polyamides such as nylon 6/6, and a blend of two or more of these.

Further, as the polycarbonate (PC), polycarbonate from bisphenols such as bisphenol A or F, polycarbonate Z and the like are used.

The plastic container or pouch-forming web used in the present invention may be a single-layer plastic container or web, or a multi-layer plastic container or web. For example, a laminate of the same type of resin in which the outer surface layer is made of linear low-density polyethylene and the inner layer is made of high-density polyethylene or isotactic polypropylene, or a heterogeneous material such as a laminate of olefin resin and polyester or polyamide. May be used as the resin laminate. Needless to say, the molded body or the web is not limited to the two-layer structure described above, and may have a multilayer structure of three layers or four or more layers.

The plastic molded container or web may contain other plastics or metal foils. For example, a gas barrier resin, aluminum foil, steel foil, or the like can be incorporated in the multilayer structure in order to impart gas permeability resistance to oxygen and the like to the formed container.

As the gas barrier resin, generally, oxygen
Transmission coefficient (PO_Two) Is 5.5 × 10 ^-12cccm / cm^Two・ Sec
・ Cm Hg or less, especially 4.5 × 10^-12 cccm / cm^Two・ Sec ・ cmH
g or less, especially when the ethylene content is 20 to 50 mol%.
And the content of unsaponified vinyl ester residue is 5 mol% or less.
The following ethylene-vinyl alcohol copolymer,
The number of amide groups per 00 is 3 to 30, especially 4 to
Homopolyamide, copolyamide contained in the range of 25
Or a blend thereof is preferably used. Of course, on
Ethylene-vinyl alcohol copolymer and polyamide
Can be used in the form of a blend,
Within a range that does not impair the essence of the product, for example, 20% by weight or less
Within the scope of other thermoplastics, such as polyolefins
Resin or other material that provides adhesion to
It can be used by rendering. These gas barriers
Resin should be provided very thin compared to the overall thickness
it can.

An oxygen absorbent-containing resin layer, a desiccant-containing resin layer, or the like can be provided as an intermediate layer in place of or together with the above-mentioned intermediate layer. Scrap resin) may be used as an intermediate layer for reuse.

The coating on the plastic molded container is performed directly on the molded body, but the coating on the pouch is performed on the web before the bag making, and then the bag is formed by heat sealing or the like.

[Application and Curing] In the present invention, the application of an ultraviolet curable paint, for example, an undercoat such as a white coat, or a top coat such as a finishing varnish can be performed using a gravure roll, a normal coating roll, or the like. it can. Generally, the coating thickness of the white coat or finishing varnish is preferably in the range of 2 to 20 μm.

On the other hand, when ultraviolet curable ink is printed on the white coat, wet-on-wet printing is performed by a known can-making printing method such as offset printing, planographic printing, gravure printing, or screen printing. It can be done in a manner.

When providing three layers of a white coat, a printing ink layer and a finishing varnish layer, a white coat layer is first formed and cured, and then the printing ink layer and the finishing varnish layer are wet-on-wet. Established in a relationship,
It is preferable that these are irradiated with ultraviolet rays to be cured at once.

As the ultraviolet light used for curing the paint, etc.,
Generally, the wavelength is 200 to 440n including the near ultraviolet region.
m, in particular from 240 to 420 nm. As an ultraviolet light source, a halide lamp, a high-pressure mercury lamp, a low-pressure mercury lamp, or the like is used. Since the thickness of the paint is quite small,
It is advantageous that the energy required for curing is considerably small, and an energy such as 500 to 5000 joules / m ² is generally sufficient.

The coating layer after the irradiation with the ultraviolet rays can be heated to a temperature of 30 to 80 ° C. to remove the distortion and post-curing, if desired. Of course, this operation is optional.

[0091]

The present invention will be described in more detail with reference to the following examples.

[Production of paint] Table 1 shows the composition of paint.
According to the composition of Table 1, a paint was produced in the following procedure. After mixing the resin, the reactive diluent, the oligomer, and the monomer excluding the resin fine particles and sufficiently stirring and dissolving, the lubricants were further added as necessary, and the lubricant was stirred and mixed. Next, an initiator, a sensitizer, and the like were added to the paint, and after dissolving, titanium oxide was added, and the mixture was sufficiently dispersed with a three-roll mill. If necessary, resin fine particles were added to this paint, and the mixture was stirred at a high speed to disperse the fine particles to produce a target paint.

[Comparison of hardness between coating film matrix and fine particles]
A composition having the coating composition shown in Table 1 except for resin fine particles and waxes was applied to a chromate-treated aluminum plate having a base plate thickness of 0.3 mm so as to have a coating thickness of 4 μm, 8 μm, and / or 12 μm. / Cm ² using a gallium lamp of 500 mJ / cm ² (illuminometer: UIT-10
2. Sensor: UVD-436PD used, all of which are manufactured by Ushio Inc.
A test piece for hardness comparison was obtained. A double-sided tape having a width of 10 mm was applied to an aluminum block having a thickness of 10 mm and the surface of which was polished, fine powder was sprinkled on the double-sided tape, and excess fine powder on the tape was blown off to form a fine particle layer on the double-sided tape. The test piece for hardness comparison is pressed on the fine particle layer so that the painted surface faces the fine particle layer, and a 300 g weight is placed thereon, and the aluminum block is fixed so as not to move. After the loaded test piece was reciprocated 10 times, the coated surface of the test piece was observed, and the magnitude of the hardness of the coating film matrix and the fine particles was determined by the presence or absence of scratches on the coating film surface. The above test was completed within 2 minutes after the coating of the hardness comparison test piece was cured. Table 2 shows the hardness comparison results between the coating matrix and the fine particles.

[Measurement of lubricity] Tribo gear HEIDON2
2-H (Shinto Chemical Co., Ltd., using cemented carbide balls, load 285)
g, a relative speed of 500 mm / min, and a measurement temperature of 20 ° C.), and the coated metal can or the coated metal plate described in Examples and Comparative Examples was fixed with a specific jig to measure the dynamic friction coefficient.

[0095] both sides of the first embodiment MotobanAtsu 0.18 mm, temper DR-9 in (metallic chromium amount 120 mg / m ² as a surface treatment coating amount was chromium oxide content 15 mg / m ^2), thickness 20 μm 2
An axially stretched polyethylene terephthalate / isophthalate copolymer film was simultaneously heat-bonded on both sides at the melting point of the film, and immediately cooled with water to obtain an organic-coated metal plate.
After the grammar wax was uniformly applied to the organic coated metal plate, it was punched into a circular plate having a diameter of 160 mm to form a shallow drawn cup according to a conventional method. The drawing ratio in this drawing step is 1.59. Next, primary and secondary redrawing processes were performed to obtain a thinned deep drawing cup. The molding conditions in the redrawing process and various characteristics of the redrawn deep drawn cup are shown below. Primary redrawing ratio 1.23 Secondary redrawing ratio 1.24 Redrawing die action corner radius of curvature 0.30 mm Redrawing die holding corner radius of curvature 1.0 mm Cup diameter 66 mm Cup height 130 mm Side wall thickness change Rate: -40% Then, after performing doming molding according to a conventional method, the deep drawing cup was heat-treated at 215 ° C. for 1 minute to remove processing distortion of the film and volatilize the lubricant. Next, the opening end was trimmed to obtain a resin-coated thinned deep drawn can having a height of 123 mm. The coating A is applied to the outer surface of the thinned deep-drawing can by a conventional method so that the coating thickness becomes 10 μm, and the coating is irradiated with ultraviolet rays of an integrated light amount of 500 mJ / cm ² by a gallium lamp having an output of 240 W / cm. Was cured. At this time, the dynamic friction coefficient of the coating film was 0.10.
This thin-painted deep-drawing can was conveyed on a normal line until the next printing process, but there was no scratching or peeling of the coating film due to rubbing between the cans or contact with the guide, and the coating can was excellent in scratch resistance Could be obtained.

Example 2 The procedure of Example 1 was repeated except that the thickness of the coating film was changed to 8 μm, and a thinned deep drawn can was prepared, the outer surface was coated, and transported to the next step. There was no peeling, and a coated can with excellent scratch resistance was obtained. The dynamic friction coefficient of this painted can is 0.
It was 10.

Example 3 The same procedure as in Example 1 was carried out except that the paint E was used and the thickness of the coating film was changed to 4 μm. There was no scratching or peeling of the coating film, and a coated can with excellent scratch resistance was obtained. The dynamic friction coefficient of this paint can was 0.09.

Example 4 The procedure of Example 1 was repeated except that the paint H was used. A thinned deep-drawn can was prepared, the outer surface was coated, and transported to the next step. Thus, a coated can having excellent scratch resistance was obtained. The dynamic friction coefficient of this paint can is 0.09
Met.

Example 5 A thin-walled deep-drawn can was prepared, coated on the outer surface, and transported to the next step in the same manner as in Example 1 except that the paint I was used. Thus, a coated can having excellent scratch resistance was obtained. The dynamic friction coefficient of this paint can is 0.12
Met.

Example 6 The procedure of Example 1 was repeated, except that the paint K was used. A thinned deep-drawn can was prepared, the outer surface was coated, and transported to the next step. Thus, a coated can having excellent scratch resistance was obtained. The dynamic friction coefficient of this paint can is 0.11
Met.

Example 7 The procedure of Example 1 was repeated, except that the paint L was used. A thinned deep drawn can was produced, the outer surface was coated, and the next step was carried out. Thus, a coated can having excellent scratch resistance was obtained. The dynamic friction coefficient of this paint can is 0.14
Met.

Example 8 An aluminum alloy material (3004-
H39), a disc having a diameter of 140 mm was punched out, cup-formed with a drawing ratio of 1.6, redrawn (with a drawing ratio of 1.3) and ironed (3 steps, total thinning rate 65%), and an inner diameter 66
mm drawn ironing cups were molded. After the drawn and ironed cup is subjected to doming molding according to a conventional method, the height is reduced to 12 mm.
The opening end was trimmed so as to have a thickness of 3 mm, washed, treated and dried according to a conventional method to obtain an aluminum squeezed and ironed can. Paint A was applied on the outer surface side of this aluminum drawn ironing can by a conventional method so that the film thickness became 10 μm, and the output was 24
500mJ integrated light quantity by gallium lamp of 0W / cm
/ Cm ² of UV light was applied to cure the coating. At this time, the dynamic friction coefficient of the coating film was 0.10. This aluminum drawn and ironed can was conveyed on a normal line until the next printing process, but there was no scratching or peeling of the coating film due to rubbing between the cans or contact with the guide, and a coated can with excellent scratch resistance was obtained. I was able to.

Example 9 The procedure of Example 8 was repeated, except that the paint J was used, to prepare an aluminum drawn ironing can, to coat the outer surface, and to transport the product to the next step. A coated can with excellent scratch resistance was obtained. The dynamic friction coefficient of this painted can is 0.
It was 11.

Example 10 Raw plate thickness 0.245 mm, temper 4, E2.8 / 2.8
A disk with a diameter of 142 mm was punched out of the tinplate, cup-formed at a drawing ratio of 1.6, redrawn (drawing ratio of 1.3) and ironed (3 steps, 67% total reduction), and drawn and drawn with an inner diameter of 66 mm. A cup was molded. This squeezing and ironing cup is trimmed at the opening end so that the height becomes 123 mm, and washed, treated and dried according to a conventional method.
A steel drawn iron can was obtained. Paint B was applied to the outer surface side of this steel drawn ironing can by a conventional method so that the coating thickness became 10 μm, and irradiated with ultraviolet rays of an integrated light amount of 500 mJ / cm ² by a gallium lamp having an output of 240 W / cm,
The coating was cured. The dynamic friction coefficient of the coating film at this time was 0.08
Met. The steel drawn and ironed can was conveyed on a normal line until the next printing step, but there was no scratching or peeling of the coating film due to rubbing between the cans or contact with the guide, and a coated can with excellent scratch resistance was obtained. I was able to.

[0105] Example 11 MotobanAtsu 0.22 mm, tone Shitsudo T4CA (metallic chromium amount 120 mg / m ² as a surface treatment coating amount was chromium oxide content 15 mg / m ²⁾ on one side of the tin-free steel, heat After applying a curable paint for the inner surface of the can and baking it by a conventional method, paint A was applied to the other surface of the tin-free steel so that the film thickness became 10 μm, and the output was 240.
500mJ / integrated light quantity by gallium lamp of W / cm
The coating film was cured by irradiating with ultraviolet rays of cm ² . At this time, the dynamic friction coefficient of the coating film was 0.10. Next, the coated plates were stacked, transported to a printing line, and then conveyed to a printing machine in a normal process. As a result, a coated plate for cans having no scratches or peeling of the coating film and having excellent scratch resistance was obtained.

Comparative Example 1 The procedure of Example 1 was repeated, except that the paint G was used, to produce a thin-walled deep drawn can, to coat the outer surface, and to carry out the next step. Although the dynamic friction coefficient of this paint can was 0.12, since it did not contain fine resin particles, a large number of scratches and peeling of the coating film occurred at the lower portion of the can body during transportation, and the scratch resistance of the paint can was poor.

Comparative Example 2 The procedure of Example 1 was repeated, except that the thickness of the coating film was changed to 4 μm, a thinned deep drawn can was prepared, the outer surface was coated, and transported to the next step. Although the dynamic friction coefficient of this coated can was 0.11, the thickness of the coated film was 0.31 times the average particle size of the resin fine particles and was outside the range of the present invention. Scratches and fine peeling occurred, and the scratch resistance of the painted can was poor.

Comparative Example 3 The procedure of Example 3 was repeated except that the thickness of the coating film was changed to 8 μm. Although the dynamic friction coefficient of this coated can was 0.11, the thickness of the coating was 1.6 times as large as the average particle size of the fine resin particles, so that the coating caused damage and fine peeling at the bottom of the can body due to transport. The scratch resistance of the painted can was poor.

Comparative Example 4 The procedure of Example 1 was repeated, except that the coating material D was used, to produce a thin-walled deep-drawn can, to perform outer surface coating, and to carry it to the next step. Although the dynamic friction coefficient of this coated can was 0.11, the content of the fine resin particles was 1%, which was less than the range of the present invention. The scratch resistance of the painted can was poor.

Comparative Example 5 The procedure of Example 1 was repeated, except that the paint F was used, to produce a thin-walled deep-drawn can, to coat the outer surface, and to carry it to the next step. Excessive resin fine particles resulted in poor coating properties, resulting in a can with poor coating appearance, and fine peeling of the coating film occurred even during transportation.
The dynamic friction coefficient of this paint can was 0.10.

Comparative Example 6 The procedure of Example 1 was repeated, except that the paint C was used, to produce a thin-walled deep-drawn can, to coat the outer surface, and to carry it to the next step. The coefficient of kinetic friction of this painted can is 0.24, and the lubricity is out of the range of the present invention. Was bad.

Comparative Example 7 The procedure of Example 1 was repeated, except that the coating material M was used, to produce a thin-walled deep drawn can, to coat the outer surface, and to carry out the next step. Although the dynamic friction coefficient of this coated can was 0.15, the fine resin particles were harder than the coating matrix, so that the coating resulted in damage to the coated film at the bottom of the can and fine peeling, resulting in poor scratch resistance of the coated can. . Table 3 summarizes the results obtained in the above Examples and Comparative Examples.

[0113]

[Table 1] (5) Trade name Hitachil 1140 Hitachi Chemical Co., Ltd. (20) Trade name S-395 N5 Shamrock Technologie
s Inc. (21) Product name S-395 N2 Shamrock Technologie
s Inc. (22) Trade name SST-2 Shamrock Technologie
s Inc. (23) Trade name ARX-15 Sekisui Chemical Co., Ltd. (24) Trade name MBX-12 Sekisui Chemical Co., Ltd.

[0114]

[Table 2]

[0115]

[Table 3]

[0116]

According to the present invention, the UV-curable paint contains 2 to 10% by weight of resin fine particles, and a part of the resin fine particles is embedded in the coating film and the other part is coated with the coating film. Paint on the substrate to protrude beyond the smooth surface of
By UV curing, the scratch resistance of the cured coating film can be significantly improved.

First, in the UV-curable coating, the resin is cured without heating, so that fine resin particles can be present in the coating film while maintaining the particle structure. This is the same even when the resin particles have a low softening point.

In the present invention, coating and ultraviolet curing are performed so that a part of the resin fine particles is embedded in the coating film and another part protrudes from the smooth surface of the coating film. Due to the lubricity of the fine resin particles, the scratch resistance when the coating film is rubbed is eliminated. That is, the resin fine particles act to prevent direct contact between another object and the surface of the cured coating film, and reduce friction with the object due to its own lubricity. Actually, when the surface of the coating film after ultraviolet curing is observed with an electron microscope, it is confirmed that the resin fine particles are distributed in the form of islands in the sea of the ultraviolet curing coating film. FIG.
1 is a schematic diagram of a sea-island distribution created by tracing an electron micrograph image.

Further, by making the fine resin particles have a hardness smaller than the hardness of the coating film matrix, the fine particles absorb the impact when the fine resin particles come into contact with an object, thereby preventing damage to the coating film. .

[Brief description of the drawings]

FIG. 1 is an explanatory diagram for explaining a state of a coating film of a coating structure in the present invention.

FIG. 2 is a schematic diagram of a sea-island distribution created by tracing an electron micrograph image.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Substrate 2 Tin-free steel (TFS) 3 Polyethylene terephthalate (PET) film 4 UV curable coating film 5 Lubricant resin particles 6 Coating film surface

────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission date] August 21, 1997

[Procedure amendment 1]

[Document name to be amended] Drawing

[Correction target item name] Figure 2

[Correction method] Change

[Correction contents]

FIG. 2

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Shinya Otsuka 1950-49, Esthe City 4th Building 301, Rokuura-cho, Kanazawa-ku, Yokohama-shi, Kanagawa 301

Claims (9)

[Claims] 1. An ultraviolet-curable paint containing 2 to 10% by weight of resin fine particles so that a part of the resin fine particles is embedded in a coating film and another part protrudes from a smooth surface of the coating film. And a coating structure having excellent scratch resistance, which is obtained by coating a substrate and curing it with ultraviolet rays. 2. The resin fine particles have an average particle size of 5 to 15 μm, and the smooth portion of the cured coating film has a thickness of 0.5 to 1 times the average particle size of the resin fine particles. Item 6. The painted structure according to Item 1. 3. The coated structure according to claim 1, wherein the resin fine particles have a hardness smaller than the hardness of the coating film matrix. 4. The coated structure according to claim 1, wherein the resin fine particles have a glass transition point (Tg) of room temperature or lower. 5. The coated structure according to claim 1, wherein the UV-curable paint contains a lubricant which is liquid at a temperature of 50 ° C. or lower. 6. The coating structure according to claim 1, wherein the ultraviolet-curable coating contains 30 to 50% by weight of fine particles of titanium oxide. 7. The coated structure according to claim 1, wherein the resin fine particle-containing cured coating film has a dynamic friction coefficient of 0.2 or less. 8. The coated structure according to claim 1, wherein the substrate is a metal can. 9. The coated structure according to claim 1, wherein the substrate is a metal plate for a can.