JP2000080343A - Electron-beam-curing adhesive and polyester film- laminated metal plate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an adhesive which gives a PET-laminated metal plate which is excellent in long-time usability and blocking resistance of its adhesive layer and is good in adhesiveness, processibility and retort resistance. SOLUTION: This electron beam-curing adhesive contains (a) 100 pts.wt. of a polyester resin which is obtained by adding a polybasic acid to a polyester prepolymer having hydroxyl groups and has a number average molecular weight of 10,000-40,000, the ratio of the weight average molecular weight to the number average molecular weight (Mw/Mn) of 2.5-7.0, a glass transition temperature of 20-55 deg.C, a hydroxyl value of 3-15 KOHmg/g and an acid value of 5-30 KOHmg/g and (b) 3-30 pts.wt. of a polymerizable unsaturated oligomer having polymerizable unsaturated double bonds of 5-15 mol/kg, a number average molecular weight of 200-2,000 and a hydroxyl value of 0-20 KOHmg/g. Another objective polyester film-laminated metal plate is obtained by laminating polyester films, which may have an ink layer, with this adhesive.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electron beam curing method capable of forming an adhesive layer for a metal sheet bonded to a polyester film, which is excellent in appearance, adhesiveness to a metal sheet, blocking resistance, and long-term usability. The present invention relates to a mold adhesive, a polyester film-bonded metal plate using the electron beam-curable adhesive, and a method for producing the bonded metal plate.

[0002]

2. Description of the Related Art
BACKGROUND ART A polyester film-bonded metal plate (hereinafter sometimes referred to as a “PET laminated metal plate”) used for a beverage can or a food can is usually obtained by laminating a polyester film and a metal plate via an adhesive. (For example, Japanese Patent Application Laid-Open No. 3-87249).

[0003] Conventional PET laminated metal plates are, for example, (1) After printing and drying ink as necessary on a polyester film which is a transparent plastic film, an adhesive is applied thereon, and until it becomes tack-free. Drying (typically, about 50 to 150 ° C. for several seconds)
(2) A step of heating (typically at about 160 to 170 ° C. for about 0.5 seconds) and press-bonding the polyester film having the adhesive layer formed thereon and the metal plate to cure the metal sheet.

[0004] However, the above-mentioned conventional manufacturing method has the following problems.

[0005] 1. In order to satisfy the conditions that can be manufactured in a short time on a high-speed production line due to the necessity of mass production of PET laminated metal sheets in recent years, the baking furnace must be lengthened, the equipment becomes large, the equipment cost becomes enormous, and it is wide. Requires factory space.

[0006] 2. In the conventional manufacturing method, when the laminating speed is higher than 150 m / min, or when the laminating temperature is lower than 160 ° C., a portion where sufficient bonding cannot be performed appears, and the appearance tends to be uneven.

[0007] 3. Beverage cans or food cans manufactured from PET-laminated metal sheets obtained by conventional methods have poor processability (neck processing, flange processing, bead processing, etc.) or have welding heat and Heat of baking of side seam paint (weld repair paint) (maximum temperature 230 ~
After retort treatment at 280 ° C. for about 7 to 100 seconds), whitening or blistering occurs, a water spot (water mark) -like pattern is formed on the surface of the polyester film, gloss is reduced, and surface finish is reduced. Cheap.

In order to solve the above-mentioned problems, the present inventors first disclosed in Japanese Patent Application Laid-Open No. Hei 6-192637, using an electron beam-curable adhesive as an adhesive, and using an electron beam-curable adhesive on a metal plate. A method was proposed in which a polyester film having an ink layer was adhered to the film through the polyester film, and then irradiated with an electron beam through the polyester film and cured to obtain a film-laminated metal plate.

The above problem was solved by the method according to this proposal. However, a polyester film obtained by laminating the above ink layer and adhesive layer (hereinafter referred to as “laminated film”)
After drying the adhesive layer), the adhesive layer is usually wound into a coil and stored until use, and the coil is unwrapped and bonded to a metal plate at the time of use. However, the change in the degree of curing of the adhesive layer during storage is large, and this curing weakens the adhesive force between the adhesive layer and the metal plate. Was. In addition, in order to reduce the change in the degree of curing of the adhesive layer and extend the period in which lamination is possible, after laminating the laminated film, within a short period of time, for example, within 5 days, when laminated on a metal plate, wrinkles are formed on the film. Therefore, problems such as poor appearance are likely to occur and the adhesive is likely to protrude from the film surface, so that good lamination cannot be performed unless a aging period of 5 days or more has elapsed after the production of the laminated film. The use time of the laminated film was severely restricted.

[0010] The present inventors have solved the above-mentioned problems, and it has become possible to perform a good lamination about one day after the production of the laminated film, and it is also possible to laminate the laminate at least three months after the production of the laminated film. And a PET-laminated metal plate obtained by laminating the laminated film on a metal plate, having excellent performance as a PET-laminated metal plate such as appearance, workability, adhesion between the polyester film and the metal plate, and retort resistance. We conducted intensive research to obtain an adhesive that can be used.

As a result, it has been found that the above object can be achieved by an electron beam-curable adhesive containing a specific polyester resin modified with a polybasic acid and a polymerizable unsaturated oligomer, and the present invention has been completed.

[0012]

That is, the present invention provides:
(A) A polyester resin obtained by subjecting a hydroxyl group-containing polyester prepolymer to an addition reaction with a polybasic acid, having a number average molecular weight of 10,000 to 40,000, a weight average molecular weight (Mw) and a number average molecular weight (Mn). Ratio (Mw / M
n) is 2.5 to 7.0, and the glass transition temperature is 20 to 55.
° C, hydroxyl value 3-15KOHmg / g, acid value 5-3
Polyester resin 10 in the range of 0 KOHmg / g
(B) 5 to 15 mol / kg amount of polymerizable unsaturated double bond per 0 parts by weight and number average molecular weight of 200 to
The present invention provides an electron beam-curable adhesive characterized by containing 2,000 and 3 to 30 parts by weight of a polymerizable unsaturated oligomer having a hydroxyl value in the range of 0 to 200 KOHmg / g.

The present invention also relates to a polyester film-bonded metal comprising a metal plate and a polyester film optionally having an ink layer laminated on one or both sides of the metal plate via the above-mentioned electron beam-curable adhesive layer. The board is provided.

Further, the present invention provides (1) a step of applying and drying the above-mentioned electron beam-curable adhesive on a polyester film which may have an ink layer, and (2) providing the dried adhesive layer. (3) unwinding the coil of the polyester film having the adhesive layer wound in the coil shape, and contacting the adhesive layer surface of the polyester film with one or both surfaces of the metal plate. And a step of thermocompression bonding so as to face each other.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION First, the electron beam-curable adhesive of the present invention will be described in detail.

The adhesive of the present invention contains a polyester resin (a) and a polymerizable unsaturated oligomer (b) as essential components.

Polyester Resin (a) The polyester resin (a) is obtained by subjecting a polybasic acid to an esterification reaction with a hydroxyl group-containing polyester prepolymer, which is an esterified product containing a polybasic acid component and a polyhydric alcohol component as main raw materials. It is a polyester resin.

The polyester resin (a) has a number average molecular weight of 10,000 to 40,000, preferably 12,000.
0 to 22,000, the ratio (Mw / Mn) of the weight average molecular weight (Mw) to the number average molecular weight (Mn) is 2.5 to 7.0,
Preferably it is 3.0 to 6.2, and the glass transition temperature is 2
0 to 55 ° C, preferably 20 to 40 ° C, and a hydroxyl value of 3 to
25KOHmg / g, preferably 5-15KOHmg / g
g, acid value is 5 to 30 KOHmg / g, preferably 8 to 2 KOHmg / g.
Suitably, it is in the range of 0 KOH mg / g.

In the hydroxyl group-containing polyester prepolymer used for producing the polyester resin (a), the polybasic acid component which is a main raw material component of the prepolymer includes:
For example, phthalic anhydride, isophthalic acid, terephthalic acid, tetrahydrophthalic anhydride, hexahydrophthalic anhydride,
Succinic acid, fumaric acid, adipic acid, azelaic acid, sebacic acid, dodecandioic acid, maleic anhydride, itaconic acid,
One or more dibasic acids selected from dimer acids and the like and lower alkyl esterified products of these acids are mainly used, and if necessary, trivalent or more trimeric such as trimellitic anhydride, methylcyclohexentricarboxylic acid, and pyromellitic anhydride. Are used in combination. These polybasic acid components can be used alone or in combination of two or more. As the acid component, a monobasic acid such as benzoic acid, crotonic acid, or pt-butylbenzoic acid may be added to the above polybasic acid component, if necessary.

Examples of the polyhydric alcohol component which is a main raw material component of the hydroxyl group-containing polyester prepolymer include, for example, ethylene glycol, diethylene glycol, propylene glycol, 1,4-butanediol, neopentyl glycol, 3-methylpentanediol, 1,4 -Hexanediol, 1,6-hexanediol, cyclohexanedimethanol, hydrogenated bisphenol A, ethylene oxide adduct of bisphenol A, bisphenol A
A dihydric alcohol such as a propylene oxide adduct is mainly used, and if necessary, a trihydric or higher polyhydric alcohol such as glycerin, trimethylolethane, trimethylolpropane, and pentaerythritol can be used in combination. These polyhydric alcohols can be used alone or in combination of two or more.

The esterification or transesterification reaction between the acid component and the polyhydric alcohol component can be carried out by a method known per se. For example, the acid component and the polyhydric alcohol component are reacted at a temperature of about 180 to 250 ° C. It can be obtained by polycondensation at a temperature.

The hydroxyl group-containing polyester prepolymer obtained as described above has a number average molecular weight of 9,000 to
39,000, preferably 11,000 to 21,000
It is suitable that the hydroxyl value is within the range of 8 to 45 KOHmg / g.

The hydroxyl group-containing polyester prepolymer obtained as described above is added to maleic acid, maleic anhydride, phthalic anhydride, trimellitic anhydride, adipic acid,
A polyester resin (a) can be produced by subjecting a polybasic acid such as azelaic acid or dimer acid to an addition reaction, half-esterifying a part of the hydroxyl groups in the prepolymer and introducing a carboxyl group. As the polybasic acid used in the half esterification reaction, an acid anhydride is particularly preferable. The half-esterification reaction can be performed by a method known per se, and can be obtained, for example, by reacting the hydroxyl group-containing polyester prepolymer with a polybasic acid anhydride at a temperature of about 170 to 190 ° C. .

In the adhesive of the present invention, the polyester resin (a) can be used alone or in combination of two or more.

Polymerizable unsaturated oligomer (b) The polymerizable unsaturated oligomer (b) has one or more, preferably two to four, polymerizable unsaturated double bonds in one molecule, 5-15 mol / kg, preferably 5-10 mol / k, of the polymerizable unsaturated double bond in the oligomer
g, having a number average molecular weight of 200 to 2,000, preferably 300 to 1,500, and a hydroxyl value of 0 to 200 mg.
KOH / g, preferably 30-80 mg KOH / g.

The resin species of the polymerizable unsaturated oligomer (b) is not particularly limited, and examples thereof include a modified polyester resin, an acrylic resin, a modified urethane resin, and a modified epoxy resin.

The modified polyester resin oligomer is
For example, it can be obtained by introducing a polymerizable double bond by esterifying a polymerizable unsaturated carboxylic acid such as acrylic acid to a hydroxyl group-containing low molecular weight polyester having a number average molecular weight of about 1,900 or less. The hydroxyl group-containing low molecular weight polyester is prepared by using a polybasic acid component and a polyhydric alcohol component as main raw materials used in the production of the hydroxyl group-containing polyester prepolymer for producing the polyester resin (a). Can be obtained by polycondensation so that the molecular weight falls within the above range. Commercially available modified polyester resin oligomers include, for example, Alonix M-7100, M-8100,
9050 (both manufactured by Toa Gosei Chemical Industry Co., Ltd.)
(Product name).

The acrylic resin oligomer is, for example,
Hydroxyl groups having a number average molecular weight of about 1,900 or less, a low molecular weight acrylic resin having a functional group such as a carboxyl group or an epoxy group, a reactive group having a reactivity with a functional group in the acrylic resin and a polymerizable unsaturated group. Can be obtained by reacting the polymerizable unsaturated compound having a reactive group with a polymerizable unsaturated compound under a condition that the polymerizable unsaturated group does not disappear, thereby introducing a polymerizable double bond into the low molecular weight acrylic resin. . Commercial products of the acrylic resin oligomer include, for example, Alonix M-305 and M-450 (all of which are manufactured by Toa Gosei Chemical Industry Co., Ltd., trade names).

The modified urethane resin oligomer is, for example,
Ethylene oxide is reacted with isocyanuric acid to introduce a hydroxyl group, and the hydroxyl group-containing isocyanuric acid has a polymerizable unsaturated group containing a functional group reactive with a hydroxyl group such as a carboxyl group-containing polymerizable unsaturated compound such as acrylic acid. It can be obtained by reacting a saturated compound to introduce a polymerizable unsaturated group. Commercially available modified urethane resin oligomers include, for example, Alonix M-31
And M-215 (all of which are manufactured by Toa Gosei Chemical Industry Co., Ltd., trade names).

The modified epoxy resin oligomer is, for example,
It can be obtained by reacting a carboxyl group-containing polymerizable unsaturated compound such as acrylic acid with an epoxy group-containing compound having one or more, preferably two or more epoxy groups to introduce a polymerizable unsaturated group.

In the adhesive of the present invention, the polymerizable unsaturated oligomer (b) can be used alone or in combination of two or more.

In the adhesive of the present invention, the compounding amount of the polymerizable unsaturated oligomer (b) is in the range of 3 to 30 parts by weight, preferably 5 to 15 parts by weight per 100 parts by weight of the polyester resin (a). Is preferred in terms of curability, adhesion, blocking resistance, and the like.

The adhesive of the present invention contains the polyester resin (a) and the polymerizable unsaturated oligomer (b) as essential components, and comprises the polyester resin (a) and the polymerizable unsaturated oligomer (b). Although it can be, for the purpose of improving the coating workability of the adhesive, an organic solvent is usually added, and further, if necessary, for example, a curing agent, a curing catalyst, an antiblocking agent, a coloring pigment, a lubricating property. An imparting agent, a silane coupling agent, an antifoaming agent, an antistatic agent, and the like can be appropriately compounded.

The organic solvent can dissolve or disperse the adhesive component, for example, toluene, xylene,
Hydrocarbon solvents such as Solvesso # 150 (manufactured by Esso Petroleum Corporation, high boiling hydrocarbon petroleum solvents), ketone solvents such as methyl ethyl ketone, methyl isobutyl ketone and cyclohexanone, ethyl acetate, butyl acetate, ethylene glycol monoethyl ether acetate; Examples include ester solvents such as ethylene glycol monobutyl ether acetate and ethylene glycol monoethyl ether acetate, and one or more of these can be appropriately selected and used.

The above-mentioned curing agent can react with the polyester resin (a) and, if necessary, the polymerizable unsaturated oligomer (b) by heating or the like to cure the adhesive. An isocyanate compound, an amino resin, and the like can be given. Among them, a polyisocyanate compound is preferable from the viewpoint of adhesion to the PET film surface and the like.

The polyisocyanate compound may be a non-blocked polyisocyanate compound in which isocyanate groups are not blocked, or a blocked polyisocyanate compound in which at least one of the isocyanate groups in the molecule is blocked. Or a mixture thereof.

Specific examples of the non-blocked polyisocyanate compound include aliphatic diisocyanates such as hexamethylene diisocyanate and trimethylhexamethylene diisocyanate; cycloaliphatic diisocyanates such as hydrogenated xylylene diisocyanate and isophorone diisocyanate; Aromatic diisocyanates such as isocyanate and 4,4'-diphenylmethane diisocyanate;
4,4 ', 4 "-triisocyanate, 1,3,5-triisocyanatobenzene, 2,4,6-triisocyanatotoluene, 4,4'-dimethyldiphenylmethane
Organic polyisocyanate itself such as a polyisocyanate compound having three or more isocyanate groups such as 2,2 ', 5,5'-tetraisocyanate, or each of these organic polyisocyanates and polyhydric alcohol, low molecular weight polyester Examples thereof include an adduct with a resin or water, a cyclized polymer of the above-mentioned organic polyisocyanates, and an isocyanate / biuret compound. Of these, isocyanurate obtained by cyclopolymerization of hexamethylene diisocyanate is preferably used.

The blocked polyisocyanate compound is
At least one isocyanate group in the molecule of the non-blocked polyisocyanate compound is blocked by a blocking agent, has at least one blocked isocyanate group in the molecule, and has a blocked isocyanate group. It may or may not have.

Examples of the blocking agent include phenols such as phenol, cresol and xylenol; lactams such as ε-caprolactam, δ-valerolactam, γ-butyrolactam and β-propiolactam; methanol, ethanol and n-propyl alcohol Alcohols such as isopropyl alcohol, n-butyl alcohol, isobutyl alcohol, tert-butyl alcohol, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monoethyl ether, propylene glycol monomethyl ether, and benzyl alcohol; formamidoxime, acetoald Kisime, acetoxime, methyl ethyl ketoxime, diacetyl monooxime, benzophenone oxime, cyclohexane Oxime, such as oxime system;
Examples of the blocking agent include active methylene compounds such as dimethyl malonate, diethyl malonate, ethyl acetoacetate, methyl acetoacetate, and acetylacetone. Among them, oxime-based blocking agents are preferably used.

When a curing agent is blended, the amount of the curing agent is preferably within a range of usually 30 parts by weight or less per 100 parts by weight of the total of the components (a) and (b).

When a polyisocyanate compound is used as a curing agent, the total of the components (a) and (b) is 10
The range of 2 to 10 parts by weight of the non-blocked polyisocyanate compound and 0 to 20 parts by weight of the blocked polyisocyanate compound per 0 parts by weight is preferred. By using both a non-blocked polyisocyanate compound and a blocked polyisocyanate compound as a curing agent, curing properties, high-speed lamination properties, PET
This makes it easier to balance, for example, extending the usable life of the film.

The curing catalyst is compounded for the purpose of accelerating the reaction of the curing agent. When the curing agent contains a blocked polyisocyanate compound, for example,
Organics such as tin octylate, dibutyltin di (2-ethylhexanoate), dioctyltin di (2-ethylhexanoate), dibutyltin dilaurate, dibutyltin oxide, dioctyltin oxide, and lead 2-ethylhexanoate A metal catalyst or the like is preferably used. When a curing catalyst is blended, the amount of the curing catalyst depends on the component (a),
Usually, the amount is preferably in the range of 0.01 to 5 parts by weight based on 100 parts by weight of the total of the component (b) and the curing agent.

The anti-blocking agent is formed by adding an adhesive to PE
After unwinding the coil after winding the laminated film for laminating a metal plate applied and dried on a T film into a coil, the adhesive layer and the non-coated surface of the PET film not coated with the adhesive It is compounded as necessary to prevent the adhesive from adhering to the surface of the PET film even if the coil adheres and the coil cannot be unwound due to the adhesion of the gap. It is.

Examples of the antiblocking agent include extenders such as silica fine powder, barium sulfate, calcium carbonate, talc, mica, and clay; polyolefins such as polyethylene fine particles, acid-modified polyethylene fine particles, maleated polypropylene fine particles, and polypropylene fine particles. Fine particles, nylon fine particles, acrylic resin fine particles, silicon rubber fine particles, urethane resin fine particles, phenol resin fine particles, organic resin fine particles such as polytetrafluoroethylene fine particles, and the like can be given. The organic resin fine particles have an average particle diameter of 0.1 to 40 μm, preferably 1 to 1 μm.
It is preferable that the softening point is within the range of 0 μm and the softening point is within the range of 100 to 200 ° C. As the resin type, polyethylene, polypropylene, and nylon are particularly preferable.

When the above antiblocking agent is blended,
The compounding amount is per 100 parts by weight of the total amount of the polyester resin (a) and the polymerizable unsaturated oligomer (b),
Usually, it is in the range of 0.1 to 50 parts by weight, especially when the antiblocking agent is an extender,
The amount is preferably within a range of from 50 to 50 parts by weight, more preferably from 10 to 40 parts by weight.
It is preferred that the amount be in the range of ２０20 parts by weight. When the compounding amount of the antiblocking agent is too large, the thermal softening property of the adhesive layer is reduced, and the adhesive force between the adhesive of the PET film and the metal plate is reduced, so that the lamination cannot be performed, or the laminated PET laminated metal plate or The PET film is easily peeled off from the metal plate when the processed product is subjected to retort treatment.

Examples of the coloring pigment include white pigments such as titanium oxide, other chromatic pigments, and brilliant pigments such as aluminum powder. When a PET laminated metal plate is used on the outer surface of a can, multicolor printing is usually performed, and a colored layer (usually a white coat) is required under a printing ink layer. If an adhesive containing a pigment is used, the adhesive can also serve as a white coat, and one manufacturing step of the can can be omitted, which is very advantageous. The blending amount of the color pigment is not particularly limited as long as the performance of the adhesive layer is not impaired, but the total amount of the polyester resin (a) and the polymerizable unsaturated oligomer (b) is 100 parts by weight. ,Normal,
It is preferable to mix in a quantitative range of 250 parts by weight or less, and in the case of a white pigment, it is usually preferable to be in the range of 50 to 250 parts by weight.

The lubricity-imparting agent is compounded for imparting lubricity to the surface of the adhesive. In order to smoothly wind the laminated film for bonding a metal plate coated with the adhesive into a coil, It is also compounded for the purpose of preventing the surface of the adhesive layer from being damaged when the coil is released. Examples of the lubricity imparting agent include fatty acid ester wax; polyolefin wax such as polyethylene wax; animal wax such as lanolin and beeswax;
Plant waxes such as carnauba wax and water wax; and waxes such as microcrystalline wax, silicon wax, and fluorine wax. When compounding a lubricity imparting agent, the compounding amount is
Usually, the amount is preferably in the range of 0.01 to 10 parts by weight per 100 parts by weight of the total of the components (a) and (b).

The above-mentioned electron beam-curable adhesive of the present invention is particularly suitable as an adhesive for a metal film bonded to a polyester film.

The polyester film-bonded metal plate of the present invention is provided on one or both sides of the metal plate via the adhesive layer.
It is a laminate of polyester films that may have an ink layer. The adhesive layer must be cured with an electron beam at the stage of the final product, but at the stage of a polyester film-bonded metal plate, the adhesive layer is cured with an electron beam even if it has been cured with an electron beam. It may not be.

Next, the method for producing a metal film laminated with a polyester film of the present invention will be described in detail.

The method for producing a metal film laminated with a polyester film of the present invention comprises: (1) applying the above-mentioned electron beam-curable adhesive of the present invention onto a polyester film (A) which may have an ink layer; Drying, (2) winding the polyester film having the dried adhesive layer into a coil, and (3) unwinding the coil of the polyester film having the adhesive layer wound into a coil, and Thermocompression bonding so that the adhesive layer surface of the polyester film is in contact with one or both surfaces of the plate.

The polyester film (A) which may have an ink layer in the above step (1) (hereinafter sometimes abbreviated as “polyester film (A)”) is
The polyester film itself having no ink layer or a polyester film having an ink layer formed thereon may be used.

As the above-mentioned polyester film, a film in which 75 to 100% of the ester repeating units are composed of ethylene terephthalate units is preferred. Examples of the acid component of the ester unit other than the ethylene terephthalate unit include phthalic acid, isophthalic acid, succinic acid, and adipic acid. The polyester film may be subjected to a surface treatment such as a corona discharge treatment on the surface thereof in order to improve the adhesiveness with the ink or the adhesive, and is preferably subjected to a surface treatment. . The thickness of the polyester film is not particularly limited, but usually, a film having a thickness of about 5 to 30 μm is suitably used.

When an ink layer is formed on a polyester film, an ink for forming an ink layer may be an ink for a polyester film, and may be any of a thermosetting ink and an actinic ray curing ink. The ink may be applied in one color or in two or more colors.

The ink layer is formed by printing ink on the polyester film by, for example, a gravure printing method.
If necessary, it can be formed by removing or curing the solvent by heating, irradiation with actinic rays, or the like.

On the polyester film (A) (when the polyester film (A) has an ink layer,
On the ink layer surface), the adhesive of the present invention is applied and dried to form an adhesive layer having no surface tackiness, whereby a laminated film for bonding metal plates can be obtained.

The application of the adhesive of the present invention onto the polyester film (A) is usually performed by a known coating means such as a roll coater method, a die coater method, a gravure method, a gravure offset method, a spray coating method, etc. The drying is performed so that the dry film thickness is about 0.3 to 15 μm.
Dry at a temperature of １８０180 ° C.

In step (2), the polyester film having an adhesive layer obtained in step (1) (laminated film for laminating metal plates) is wound into a coil. This coil is stored until it is used for bonding to a metal plate.

In step (3), the coil of the laminated film for bonding a metal plate obtained in step (2) is unwrapped and bonded to a metal plate.

Examples of the metal sheet used for the above-mentioned bonding include hot-rolled steel sheet, cold-rolled steel sheet, hot-dip galvanized steel sheet, electro-galvanized steel sheet, iron-zinc alloy-plated steel sheet, zinc-aluminum alloy-plated steel sheet, Metal plates such as nickel-zinc alloy-plated steel plate, nickel-tin alloy-plated steel plate, tinplate, chrome-plated steel plate, aluminum-plated steel plate, turn-plated steel plate, nickel-plated steel plate, stainless steel, tin-free steel, aluminum plate, copper plate, and titanium plate Materials; chemical conversion treatments, such as phosphate treatment, chromate treatment, composite oxide film treatment, etc., on these metal plate materials; white coats, etc. on the surfaces of these metal plate materials or the chemical conversion treatment metal plates And a coated metal plate such as a primer-coated metal plate having a primer layer formed thereon. In the present invention, the term “metal sheet” also includes a processed metal sheet obtained by molding a flat metal sheet such as the above-described metal sheet material, a chemical conversion-treated metal sheet or a primer-coated metal sheet into, for example, a can body. It shall be.

The conditions for laminating the metal plate on the surface of the adhesive layer of the laminated film for laminating a metal plate are such that the laminated film for laminating a metal plate does not deteriorate, and the PET film and the metal plate are sufficiently adhered to each other. There is no particular limitation as long as a PET-laminated metal plate having a good appearance is obtained. As an example of the bonding conditions, for example, the temperature of the metal plate at the time of thermocompression bonding is set to about 120 to 200 ° C. by a method using a heating roll, a method of preheating the metal plate, or the like, in a short time (usually about 2 seconds or less). And a method of laminating a metal plate and a laminated film for bonding a metal plate by thermocompression bonding. When a flat metal plate is used, a laminated film for bonding a metal plate can be heat-laminated on one or both surfaces of the flat metal plate.

The adhesive layer of the laminated metal plate obtained as described above is cured by electron beam irradiation, and this electron beam irradiation is carried out before processing a flat or similar PET laminated metal plate. May be performed, or may be performed after processing. Of course, when the PET laminated metal plate has a desired shape, it is not necessary to process the PET laminated metal plate irradiated with the electron beam.

The electron beam source accelerators used for electron beam irradiation include Cockcroft type, Cockcroft-Walton type, Van de Graf type, Resonant transformer type, Transformer type, Insulated core transformer type and Dynamitron type. , A linear filament type, an area beam type, a high frequency type and the like. The electron beam energy required to cure the adhesive layer is suitably in the range of 100 keV to 300 keV, preferably 150 keV to 200 keV. The irradiation dose is preferably from 0.2 Mrad to 15 Mrad, and particularly preferably from 1 Mrad to 5 Mrad from the viewpoint of the curability and mechanical strength of the adhesive layer. The irradiation time of the electron beam is usually
It can be about 1 second or less, and about 1/50 or less of the curing time in the case of heat curing.

The PET laminated metal sheet of the present invention is suitably used for cans such as beverage cans, food cans, miscellaneous cans, 5 gallon cans and metal lids such as caps.
The present invention can also be applied to the exterior of household appliances such as the exterior of a refrigerator.

[0065]

EXAMPLES The present invention will be described more specifically with reference to examples.

Hereinafter, both “parts” and “%” are based on weight.

Production example 1 of polyester resin (a) Production example 1 0.3 mol of terephthalic acid, 0.55 mol of isophthalic acid
Sebacic acid 0.15 mol, ethylene glycol 0.25
Mol, 1,4-butanediol 0.2 mol, neopentyl glycol 0.33 mol, 1,4-dimethylolcyclohexane 0.2 mol, trimethylolpropane 0.0
2 mol and an appropriate amount of a polycondensation catalyst were charged into an autoclave and heated to carry out an esterification reaction, and a theoretical amount of condensed water was removed to obtain a polyester prepolymer. Then, 0.25 mol of maleic anhydride was added to 1 kg of the obtained polyester prepolymer, and the mixture was heated and stirred to carry out an addition reaction. Then, the mixture was cooled and mixed solvent (toluene / methyl ethyl ketone = 50/50 (weight ratio)). ) Was added to obtain a polyester resin (a-1) having a solid content of 40%.

Preparation Examples 2 to 13 The same procedures as in Preparation Example 1 were carried out except that the polybasic acid component, the polyhydric alcohol component and the acid component added later were changed as shown in Table 1 below. A resin was obtained. Production Examples 7 to 13 are comparative polyester resin production methods. In Table 1, the compounding amount of the acid component and the alcohol component is based on the molar amount, and the compounding amount of the acid component added later is based on the molar amount based on 1 kg of a polyester prepolymer obtained by esterifying the acid component and the alcohol component. displayed.

The number average molecular weight (Mn) and the weight average molecular weight (M) of each of the polyester resins obtained in Production Examples 1 to 13 above.
w), Mw / Mn ratio, glass transition temperature (° C.), hydroxyl value (KOH mg / g), and acid value (KOH mg / g) are shown in Table 1 below.

[0070]

[Table 1]

Production Example 1 of Electron Beam Curable Adhesive The polyester resin having a solid content of 40% (a-
1) Titanium white 18 in 100 parts of solution (40 parts in solid content)
0 parts, an extender (clay) 20 parts and an appropriate amount of a mixed solvent (toluene / methyl ethyl ketone = 50/50 (weight ratio)) were added and dispersed. Then, the polyester resin 137 having a solid content of 40% was added to the dispersion. .5 parts (55 parts in solid content), "Aronix M-315" (Toa Gosei Co., Ltd.)
Polyester containing a polymerizable unsaturated group, polymerizable unsaturated double bond concentration of about 7.0 mol / kg, number average molecular weight of about 42
0, having substantially no hydroxyl group) 5 parts, “Duranate TPA-B80X” (manufactured by Asahi Kasei Corporation, hexamethylene diisocyanate-based blocked polyisocyanate compound, solid content 80%) 25 parts (solid content 20) Parts) and 3 parts of "Duranate TPA100" (manufactured by Asahi Kasei Corporation, hexamethylene diisocyanate-based polyisocyanate compound) and methyl ethyl ketone, and the solid content is 50%.
Was obtained.

Examples 2 to 12 and Comparative Examples 1 to 11 Each electron beam-curable adhesive was obtained in the same manner as in Example 1 except that the composition was changed as shown in Table 2 below. In Table 2, the amount of each component is represented by the weight of the solid content. In Table 2, (note) has the following meanings.

(* 1) EB-450: UCB s. a.
Specialty Chemicals, polymerizable unsaturated group-containing polyester oligomer, polymerizable unsaturated double bond concentration about 4
Mol / kg, number average molecular weight about 1500, hydroxyl value 50K
OH mg / g.

(* 2) Alonix M-8100: Toa Gosei Chemical Industry Co., Ltd., polymerizable unsaturated group-containing polyester oligomer, polymerizable unsaturated double bond concentration: about 6.7 mol /
kg, having a number average molecular weight of about 600 and having substantially no hydroxyl groups.

Production of PET Laminated Metal Sheets Examples 1 to 12 and Comparative Examples were applied to the corona-discharge treated surface of an ester film E5100 (a polyester film having a film thickness of 12 μm) [one surface subjected to corona discharge treatment] manufactured by Toyobo Co., Ltd. Each of the electron beam-curable adhesives obtained in 1 to 11 was applied by gravure coating so that the dry film thickness was about 3 μm. Then, the mixture was passed through a drying oven at 100 ° C. for 10 seconds to evaporate the solvent. The obtained adhesive-coated polyester film was tested for tackiness and blocking resistance on the surface of the adhesive layer based on the test method described later. The test results are shown in Table 2 below.

The polyester film coated with the adhesive and a canlite (manufactured by Nippon Steel Corporation) which is a tin plate having a thickness of 0.19 mm were subjected to a roll temperature of 180 ° C. and a roll pressure of 5.0 kg / cm ² . For heat lamination. Next, through the polyester film of the heat-laminated bonded metal plate, using an electron beam accelerator, irradiation was performed at an acceleration voltage of 270 keV and an electron beam current of 4 mA at 4 Mrad, and the adhesive layer was cured to cure each PET-laminated metal plate. Obtained.

With respect to each of the PET laminated metal plates obtained as described above, the appearance of the laminated polyester film surface and the retort adhesion resistance test were performed based on the test methods described later. The test results are shown in Table 2 below.

Test items Tackiness: Two adhesive-coated surfaces of an adhesive-coated polyester film (about 10 seconds after coming out of a drying oven) obtained by evaporating the solvent are overlapped with each other, and are sufficiently hand-operated. After pressure bonding, the two films were peeled off, and the evaluation was made based on the larger peeling area of the adhesive from the polyester film surface among the two adhesive applied surfaces. ◎: No peeling was observed on the two adhesive coated surfaces. ○: Peeling was observed, and the larger peeled area was less than 10%. Δ: The larger peeled area was 10% or more and less than 30%. C: The larger peel area is 30% or more.

Blocking resistance: Another "ester film E5100" was subjected to corona discharge treatment on the surface of the adhesive layer of the adhesive-coated polyester film obtained by evaporating the solvent, and the treated surface was coated with an epoxy-polyester overcoat. The coated surface of the coat was placed so as to face the adhesive surface, and a pressure of 10 kg / cm ² was applied thereto, followed by storage in a room at a temperature of 25 ° C. and a humidity of 60% RH for 3 days.
This storage laminated film was cut into a width of 30 mm, and the above another PET film was pulled from the dried coating surface at a pulling speed of 500 mm.
Peel strength (g / 30m) when peeling 180 ° at mm / min
m width) was measured and evaluated according to the following criteria. ：: Peel strength is less than 10 g / 30 mm width ：: Peel strength is 10 g / 30 mm width or more and 20 g / 30
Less than mm width △: 50 g / 30 when the peel strength is 20 g / 30 mm width or more.
Less than mm width ×: Peel strength is 50 g / 30 mm width or more.

Appearance of film surface: The same laminate as that prepared in the above-described blocking resistance test was applied to the surface of the dried film from the laminate film after two and four days of storage in a room. Of a PET-laminated metal plate obtained by laminating a 0.2-mm-thick tin plate on the surface of the dried coating film that appeared at a lamination temperature of 160 ° C., a linear pressure of 50 kg, and a speed of 200 m / min. The appearance of the laminate surface was evaluated according to the following criteria. ◎: No abnormality was observed on the PET laminated surface. ：: Slight skin was observed on the PET laminated surface. △: Considerable yuzu skin was observed on the PET laminated surface. X: Remarkably worn skin was observed on the PET laminated surface.

Laminating strength: A PET laminated metal plate (lamination storage time: 24 hours) prepared for the above-mentioned film surface appearance test was cut into a 15 mm width, and PET was cut.
A peel test between the film and the tin plate was performed to evaluate the difficulty of peeling according to the following criteria. ：: PET film is not peeled at all ：: Part of PET film is peeled, but peel length is 5 mm
The PET film is cut at a point of less than Δ: Part of the PET film is peeled off, but the peel length is 5 mm
Above, the PET film is cut at less than 20 mm. ×: The PET film is peeled off, and the PET film is cut off or peeled off entirely when the peel length is 20 mm or more.

The retort adhesion resistance of the processed part: The PET laminated metal plate prepared for the above-mentioned film surface appearance test was pressed with a tin plate side up using a 200 end processing machine (can lid processing machine). The peeling state of the PET film when the prepared can lid was retorted at 125 ° C. for 30 minutes in steam was evaluated according to the following criteria. ◎: No peeling of the PET film was observed at all. ○: A part of the PET film in the peripheral area was slightly peeled. Δ: A part of the PET film in the peripheral area was considerably peeled. Peel over.

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[Table 2]

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[Table 3]

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By using the adhesive of the present invention,
An adhesive layer having excellent long-term usability can be formed, and the polyester film formed with the adhesive layer has a good blocking resistance of the adhesive layer and an excellent adhesiveness to a metal plate. is there.

The PET laminated metal plate obtained by laminating the polyester film on which the adhesive layer is formed is excellent in the appearance of the PET film surface, workability, retort resistance and the like.

The PET-laminated metal plate using the adhesive of the present invention can be suitably used for can applications such as can lids and inner and outer surfaces of cans.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Hisao Yuasa 4-171-1, Higashi-Hachiman, Hiratsuka-shi, Kanagawa Prefecture Inside Kansai Paint Co., Ltd. (72) Takako Fukuzawa 4-171-1, Higashi-Hachiman, Hiratsuka-shi, Kanagawa Seki F-term in Nishi Paint Co., Ltd. (Reference) 4F100 AB01A AK41B AK41C AK41G BA02 BA03 BA06 BA10B BA10C BA14 CA13 CA17 CB04 EC182 EH461 EJ083 EJ533 EJ861 HB31B HB31C JJ10 JK06 JL00 4J040 ED031 EF 321 EF 172 EF 172 JB07 KA09 KA35 LA01 LA02 LA05 LA06 LA08 MA02 MA10 MB03 MB05 NA08 NA09 PA30 PA33

Claims (7)

[Claims] 1. A polyester resin obtained by subjecting a hydroxyl group-containing polyester prepolymer to an addition reaction with a polybasic acid, and having a number average molecular weight of 10,000 to 40,000.
0, the ratio (Mw / Mn) of the weight average molecular weight (Mw) to the number average molecular weight (Mn) is 2.5 to 7.0, the glass transition temperature is 20 to 55 ° C., the hydroxyl value is 3 to 15 KOH mg / g,
(B) a polymerizable unsaturated double bond in an amount of 5 to 15 mol / kg and a number average molecular weight of 200 to 2 per 100 parts by weight of the polyester resin having an acid value in the range of 5 to 30 KOH mg / g; An electron beam-curable adhesive comprising: 3,000, 3 to 30 parts by weight of a polymerizable unsaturated oligomer having a hydroxyl value in the range of 0 to 200 KOH mg / g. 2. 2 to 10 parts by weight of a non-blocked polyisocyanate compound and 0 to 20 parts by weight of a blocked polyisocyanate compound per 100 parts by weight of the total of the polyester resin (a) and the polymerizable unsaturated oligomer (b). The electron beam-curable adhesive according to claim 1, comprising: 3. The method according to claim 1, wherein the antiblocking agent is contained in an amount of 1 to 50 parts by weight per 100 parts by weight of the total of the polyester resin (a) and the polymerizable unsaturated oligomer (b). 3. The electron beam-curable adhesive according to 2. 4. A white pigment is contained in an amount of 50 to 250 parts by weight per 100 parts by weight of the total amount of the polyester resin (a) and the polymerizable unsaturated oligomer (b). The electron beam-curable adhesive according to any one of the above. 5. The method according to claim 1, wherein one or both sides of the metal plate are provided.
A polyester film-bonded metal plate comprising a polyester film, which may have an ink layer, laminated via an electron beam-curable adhesive layer as described above. 6. A step of: (1) applying the adhesive according to claim 1 on a polyester film (A) which may have an ink layer and drying; and (2) applying the dried adhesive layer. (3) unwinding the coil of the polyester film having the adhesive layer wound in the coil shape, and contacting the adhesive layer surface of the polyester film with one or both surfaces of the metal plate. A process of thermocompression bonding so as to face each other. 7. The method according to claim 6, further comprising the step of: (4) irradiating the thermocompression-bonded adhesive layer with an electron beam to cure the adhesive layer.