JP2001107015A - Thermosetting adhesive - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide thermosetting adhesives for polyester film laminated metal plates which have good coating workability with reduced viscosity lowering on heating and do not much change the cured state of an adhesive layer by aging. SOLUTION: A thermosetting adhesive for polyester film laminated metal plates contains (A) a urethane modified polyester resin having a number average molecular weight of 20,000-100,000 and a weight average molecular weight of 80,000-200,000 which is obtained by reacting a polyisocyanate compound with a hydroxyl group-containing polyester resin having a number average molecular weight of 4,000-40,000 in such a manner that the equivalent ratio (OH/NCO) of the hydroxyl groups (OH) in the polyester resin to the isocyanate groups (NCO) in the polyisocyanate compound comes to 1.0-10 and (B) a blocked polyisocyanate compound.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a thermosetting adhesive for a polyester film-laminated metal plate and a method for producing a polyester film-laminated metal plate using the adhesive.

[0002]

2. Description of the Related Art Conventionally, a laminated metal plate has been applied, for example, by applying an adhesive to a bonding surface of a plastic film such as a polyester (PET) film with a roll coater, and then bonding this to a metal plate such as a steel plate. Manufactured by a combination method.

As an adhesive for a laminated metal plate, an epoxy resin-based or polyester resin-based adhesive is known.

However, the epoxy resin-based adhesive has a problem that a low molecular weight curing agent component is volatilized when the adhesive is baked and cured, and a large amount of oven fume is generated.

[0005] In addition, polyester resin adhesives generally have low viscosity, and when coated with a coating machine and laminated with a plastic film on a metal plate, the film is more likely to wrinkle. When the plate comes in contact with the wicket having a high temperature, the viscosity of the portion becomes low and the portion moves and becomes uneven, so that there is a problem that wicket abrasion occurs. Further, in the polyester resin-based adhesive, when the molecular weight of the polyester resin is increased to increase the viscosity, there is a problem that the compatibility with the crosslinking agent is reduced.

[0006] The polyester film-laminated metal plate is usually prepared by applying an adhesive to a polyester film in advance, evaporating a solvent in the adhesive by heating or the like, and drying the adhesive so as not to cure the adhesive layer. A polyester film having an adhesive layer wound in a shape,
It can be obtained by bonding to a metal plate and curing by heating. A polyester film having an adhesive layer wound in a coil shape can be bonded to a metal plate when the adhesive layer is aged and in a moderately cured state. It is preferable because the adhesive does not protrude due to the flow of the layer, and there is no difficulty in uncoiling the coil due to blocking of the wound coil. There was a problem that it was extremely limited.

[0007] An object of the present invention is to provide a coating workability without generation of oven fume, a large decrease in viscosity upon heating, no wicket abrasion, and a coiled adhesive layer. An object of the present invention is to provide a thermosetting adhesive for a polyester film-laminated metal plate, in which a cured state of an adhesive layer in a polyester film does not largely change due to aging, and a coil showing good laminating properties can be formed immediately after winding. .

[0008]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to achieve the above object, and as a result, have found that a thermosetting adhesive containing a specific urethane-containing polyester resin and a blocked polyisocyanate compound has been used. Have been achieved, and the present invention has been completed.

That is, the present invention provides (A) a hydroxyl group-containing polyester resin having a number average molecular weight in the range of 4,000 to 40,000, a polyisocyanate compound, and a hydroxyl group (OH) in the polyester resin and a polyisocyanate. (OH / N) with the isocyanato group (NCO) in the compound
CO) The number-average molecular weight obtained by the reaction so that the equivalent ratio becomes 1.0 to 10 is 20,000 to 100,000.
And a urethane-modified polyester resin having a weight average molecular weight in the range of 80,000 to 200,000, and (B)
An object of the present invention is to provide a thermosetting adhesive for a polyester film-laminated metal plate, which comprises a blocked polyisocyanate compound.

[0010] Further, the present invention provides the thermosetting adhesive,
An object of the present invention is to provide a method for manufacturing a polyester film-laminated metal plate, which is sandwiched between a polyester film and a metal plate and then heated to cure the adhesive.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.

First, the adhesive of the present invention will be described in detail.

The adhesive of the present invention is a thermosetting adhesive for a laminated metal plate containing the following urethane-modified polyester resin (A) and the following blocked polyisocyanate compound (B).

Urethane-modified polyester resin (A) The urethane-modified polyester resin as the component (A) in the adhesive of the present invention is obtained by reacting a hydroxyl group-containing polyester resin with a polyisocyanate compound.

The above-mentioned hydroxyl group-containing polyester resin comprises an esterified product of a polybasic acid component and a polyhydric alcohol component. Examples of the polybasic acid component include one or more selected from phthalic anhydride, isophthalic acid, terephthalic acid, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, succinic acid, fumaric acid, adipic acid, sebacic acid, maleic anhydride, and the like. Dibasic acids and lower alkyl esterified products of these acids are mainly used, and if necessary, monobasic acids such as benzoic acid, crotonic acid, pt-butylbenzoic acid, trimellitic anhydride, methylcyclohexenetricarboxylic acid And tribasic or higher polybasic acids such as pyromellitic anhydride. Examples of the polyhydric alcohol component include ethylene glycol, diethylene glycol, propylene glycol, 1,4-butanediol,
Dihydric alcohols such as neopentyl glycol, 3-methylpentanediol, 1,4-hexanediol, and 1,6-hexanediol are mainly used, and if necessary, glycerin, trimethylolethane, trimethylolpropane, and pentane. A trihydric or higher polyhydric alcohol such as erythritol can be used in combination. These polyhydric alcohols can be used alone or in combination of two or more. The esterification or transesterification of both components can be carried out by a method known per se.

The hydroxyl group-containing polyester resin has a number average molecular weight in the range of 4,000 to 40,000,
It is preferable that the hydroxyl value is in the range of 3 to 50 mgKOH / g.

Examples of the polyisocyanate compound to be reacted with the above-mentioned hydroxyl group-containing polyester resin include aliphatic diisocyanates such as lysine diisocyanate, hexamethylene diisocyanate and trimethylhexane diisocyanate; hydrogenated xylylene diisocyanate, isophorone diisocyanate, methylcyclohexane-2, 4 (or 2,6) -diisocyanate,
Cycloaliphatic diisocyanates such as 4,4'-methylenebis (cyclohexyl isocyanate) and 1,3- (isocyanatomethyl) cyclohexane; aromatic diisocyanates such as tolylene diisocyanate, xylylene diisocyanate and diphenylmethane diisocyanate; lysine Organic polyisocyanate itself such as tri- or higher polyisocyanate such as triisocyanate, or an adduct of each of these organic polyisocyanates with polyhydric alcohol, low molecular weight polyester resin or water, or as described above A cyclized polymer of each organic diisocyanate (for example, isocyanurate), a biuret-type adduct, and the like can be given. These can be used alone or in combination of two or more.

The reaction ratio between the hydroxyl group-containing polyester resin and the polyisocyanate compound is such that the (OH / NCO) equivalent ratio between the hydroxyl group (OH) in the polyester resin and the polyisocyanate group (NCO) in the polyisocyanate compound is as follows: It is preferable to be within the range of 1.0 to 10.

The urethane-modified polyester resin (A) is
The number average molecular weight is in the range of 20,000 to 100,000, the weight average molecular weight is in the range of 80,000 to 200,000, and the hydroxyl value is in the range of 0 to 20 mgKOH / g, preferably 2 to 15 mgKOH / g. It is preferred that there be.

Blocked polyisocyanate compound
(B) The blocked polyisocyanate compound as the component (B) in the adhesive of the present invention is obtained by blocking the isocyanate group of the polyisocyanate compound used for producing the urethane-modified polyester resin (A) with a blocking agent. It becomes. Examples of the blocking agent include phenols such as phenol, cresol and xylenol; ε-caprolactam; δ-valerolactam, γ
-Lactams such as butyrolactam and β-propiolactam; methanol, ethanol, n- or i-propyl alcohol, n-, i- or t-butyl alcohol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether , Diethylene glycol monomethyl ether,
Alcohols such as diethylene glycol monoethyl ether, propylene glycol monomethyl ether and benzyl alcohol; oximes such as formamidoxime, acetoaldoxime, acetoxime, methyl ethyl ketoxime, diacetyl monooxime, benzophenone oxime, cyclohexane oxime; dimethyl malonate,
Active methylene blocking agents such as diethyl malonate, ethyl acetoacetate, methyl acetoacetate, and acetylacetone can be suitably used. By mixing the polyisocyanate compound with the blocking agent, the isocyanate group of the polyisocyanate can be easily blocked.

In the adhesive of the present invention, the proportion of the blocked polyisocyanate compound (B) is 5 to 1 based on 100 parts by weight of the urethane-modified polyester resin (A).
It is suitably in the range of 00 parts by weight, preferably 10 to 50 parts by weight.

The adhesive of the present invention comprises the above-mentioned urethane-modified polyester resin (A) and the blocked polyisocyanate compound (B) as essential components. For the purpose of improving workability, an organic solvent is usually blended, and if necessary, for example, a curing catalyst, an antiblocking agent, a coloring pigment, a lubricity imparting agent, a silane coupling agent, an antifoaming agent, An antistatic agent or 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 curing catalyst is compounded for the purpose of accelerating the reaction between the urethane-modified polyester resin (A) and the blocked polyisocyanate compound (B).
For example, tin octylate, dibutyltin di (2-ethylhexanoate), dioctyltin di (2-ethylhexanoate), dibutyltin dilaurate, dibutyltin oxide, dioctyltin oxide, lead 2-ethylhexanoate, etc. Are preferably used. When a curing catalyst is blended, the amount of the curing catalyst is usually 0.1 part with respect to 100 parts by weight of the total of the components (A) and (B).
A range of from 0.01 to 5 parts by weight is preferred.

[0025] 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 preferably within a range of 0 μm and a softening point of 100 ° C. or higher, and polyethylene, polypropylene, and nylon are particularly preferred as resin types.

When the above antiblocking agent is blended,
The compounding amount is a total of 1 (A) and (B) components.
Per 100 parts by weight, it is usually in the range of 0.1 to 50 parts by weight, especially when the antiblocking agent is an extender, 10 to 50 parts by weight, more preferably 10 to 40 parts by weight.
It is preferably within the range of parts by weight, and when the antiblocking agent is organic resin fine particles, it is 0.1 to 30 parts by weight.
It is preferred that the amount be in the range of 1 part by weight, more preferably 1 to 20 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, 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 of the components (A) and (B) is 100%.
It can be blended in a quantitative range of usually 300 parts by weight or less per part by weight, and in the case of a white pigment, usually 50 to 3 parts by weight.
It is suitable that the amount is in the range of 00 parts by weight, preferably 100 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 to which the adhesive has been applied into a coil shape, 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 adhesive of the present invention is particularly suitable as an adhesive for producing a polyester film-laminated metal plate.

The above-mentioned laminated polyester film laminated metal plate is obtained by laminating a polyester film which may have an ink layer on one or both sides of the metal plate via the adhesive layer. The adhesive layer needs to be cured at the stage of the final product, but at the stage of the polyester film-bonded metal plate, the adhesive layer may or may not be thermally cured.

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 according to the present invention comprises: (1) a step of applying and drying the thermosetting adhesive of the present invention on a polyester film which may have an ink layer; (2) a step of winding the dried polyester film having the adhesive layer into a coil; and (3) unwinding the coil of the polyester film having the adhesive layer which has been wound into a coil to form one side of a metal plate or Thermocompression bonding so that the adhesive layer surface of the polyester film is in contact with both surfaces.

The polyester film optionally having an ink layer in the above step (1) may be a polyester film itself having no ink layer or a polyester film having an ink layer formed on a polyester film. .

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 the ink layer is formed on the polyester film, the ink for forming the ink layer may be a polyester film ink, 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.

The adhesive of the present invention is applied onto a polyester film (when the polyester film has an ink layer, usually on the surface of the ink layer) and dried to form an adhesive layer having no surface tackiness. A laminated film for plate lamination can be obtained.

The adhesive of the present invention is applied onto a polyester film by a coating method known per se such as a roll coater method, a die coater method, a gravure method, a gravure offset method, and a spray coating method. Is usually performed at a temperature of, for example, 50 to 180 ° C. in order to volatilize and remove the solvent of the adhesive layer.

In step (2), the polyester film (laminated film for bonding metal plates) having the adhesive layer obtained in step (1) 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 laminating 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 the metal plate are such that the laminated film for laminating the metal plate is not deteriorated, the polyester film and the metal plate are sufficiently bonded, There is no particular limitation as long as a polyester film laminated metal plate having a good appearance (hereinafter sometimes abbreviated as “laminated metal plate”) 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 further thermoset if necessary, but may be carried out before processing the laminated metal plate such as a flat plate. It may be done later. Of course, when the laminated metal plate has a desired shape, it is not necessary to process the laminated metal plate.

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.

[0046]

The present invention will be described more specifically with reference to the following examples. Hereinafter, “parts” and “%” are based on weight, respectively.

Synthesis Example 1 A reactor equipped with a thermometer, a stirrer, a heating device and a rectification column was charged with 45.5 mol of ethylene glycol, 58.5 mol of neopentyl glycol, 1,4-butanediol 1
9.5 mol, terephthalic acid 30 mol, isophthalic acid 55
Mol, 15 mol of adipic acid, further add a small amount of xylene for reflux, gradually heat to 250 ° C., hold at the same temperature for 5 hours, carry out esterification reaction while dehydrating,
Number average molecular weight about 20,000, weight average molecular weight about 40,
Polyester resin (a) having a hydroxyl value of about 4 mgKOH / g was obtained.

SYNTHESIS EXAMPLE 2 The procedure of Synthesis Example 1 was repeated except that 58.5 mol of neopentyl glycol was changed to a mixture of 55.9 mol of neopentyl glycol and 2.6 mol of trimethylolpropane. , Number average molecular weight about 20,000,
Weight average molecular weight about 60,000, hydroxyl value about 9 mg KO
An H / g polyester resin (b) was obtained.

Production Example 1 100 parts of the polyester resin (a) obtained in Synthesis Example 1 and 67.3 parts of toluene were mixed to form a uniform solution, and 1 part of hexamethylene diisocyanate was added with stirring to carry out a urethanization reaction. Thus, a urethane-modified polyester resin solution (1) having a solid content of 60% was obtained. The obtained resin had a number average molecular weight of about 40,000 and a weight average molecular weight of about 100,00.
0, had a hydroxyl value of about 2 mgKOH / g.

Production Example 2 The same procedure as in Production Example 1 was carried out except that the amount of toluene was changed to 67.0 parts and the amount of hexamethylene diisocyanate was changed from 1 part to 0.5 part. 60% urethane-modified polyester resin solution (2)
I got The obtained resin had a number average molecular weight of about 25,000.
0, weight average molecular weight about 80,000, hydroxyl value about 3 mg
KOH / g.

Production Example 3 In Production Example 1, the polyester resin (b) 10 obtained in Synthesis Example 2 was replaced with 100 parts of the polyester resin (a).
Except that 0 part was used, the same procedure as in Production Example 1 was carried out to obtain a urethane-modified polyester resin solution (3) having a solid content of 60%. The obtained resin had a number average molecular weight of about 60,000, a weight average molecular weight of about 170,000, and a hydroxyl value of about 2 mg KO.
H / g.

Example 1 133.3 parts of a urethane-modified polyester resin solution (1) having a solid content of 60% obtained in Production Example 1 (80 parts in terms of solid content)
, 200 parts of titanium white, hexamethylene diisocyanate solution blocked with methyl ethyl ketoxime 2
6.7 parts (20 parts in terms of the active ingredient), 0.5 parts of dibutyltin dilaurate, 30 parts of toluene and 30 parts of methyl ethyl ketone were blended and sufficiently mixed to obtain an adhesive.

Examples 2 to 11 and Comparative Examples 1 to 8 Each adhesive was obtained in the same manner as in Example 1 except that the composition was as shown in Table 1 below.

Each of the adhesives obtained in Examples 1 to 11 and Comparative Examples 1 to 8 was applied on a corona discharge treated surface of a PET film having a thickness of 12 μm and a width of 100 mm to a dry coating weight of 1.5 g /
m ^2, and the solvent was evaporated to dryness. Then, the adhesive layer surface of the PET film was overlaid on a tin-free steel plate preheated to 190 ° C., and a pressure of 4 ° C. was applied using a 190 ° C. hot roll.
Thermocompression bonding was performed at 0 kg / cm ^{2 at} a speed of 100 m / min. Thereafter, baking was performed at 190 ° C. for 10 minutes to obtain each PET laminated metal plate. Various tests were performed on the obtained PET laminated metal plates according to the following test methods. The test results are shown in Table 1 below.

Test Method Appearance: The appearance (bubbles, wrinkles, etc.) of the PET film side of the PET laminated metal plate was visually evaluated according to the following criteria. ：: Good appearance without generation of bubbles and wrinkles. Δ: Slight generation of bubbles and wrinkles is observed, and somewhat poor. ×: Generation of many bubbles and wrinkles is observed and defective.

Adhesive run-out resistance: The presence or absence of the run-out of the adhesive from the left and right ends of the PET laminated metal plate was visually evaluated. ：: Adhesive does not protrude and is good ×: Adhesive protrudes and is poor.

Wicket abrasion resistance: 100 × 200 m on a conveyor wicket having many conical iron protrusions toward the top in a conveyor oven.
PET of PET laminated metal sheet cut to size of m
The film was placed so that the film surface side was in contact with the six tips of the iron projections, and baked in the conveyor oven for 120 seconds so that the maximum temperature (PMT) of the metal plate reached 200 ° C. PE of baked PET laminated metal plate
The T film surface was visually observed and evaluated according to the following criteria. ：: no change was observed and Δ was good, but traces of protrusions were seen, but metal base was not seen. ×: traces of protrusions were seen and metal base was visible.

Adhesion: PET laminated metal plate
JIS K before and after retort treatment at 5 ° C for 30 minutes
-5400 8.5.2 (1990).
Make a cut to reach the metal surface with a knife on the PET film surface of the T-laminated metal plate, make 100 squares of 1 mm x 1 mm, attach a cellophane adhesive tape to the surface, and peel off instantly Record the number of squares left without doing so.

Processability: PET of PET laminated metal plate
A cross cut reaching the metal surface was made on the film surface with a knife, and the intersection of the cuts was extruded from the back side by 6 mm using an Erichsen tester, and the state of adhesion of the PET film at the extruded portion was evaluated according to the following criteria. ：: PET film does not peel off ×: PET film peels from the intersection of cross cut

Retort resistance after processing: The test piece subjected to the above-described processing test was retorted at 125 ° C. for 30 minutes.
The state of adhesion of the PET film was evaluated. ○: PET film does not peel off △: PET film peels off from intersection of cross cut, but peeling is not observed except at the extruded part ×: PET film peels off from intersection of cross cut,
Peeling is also observed at places other than the extruded part.

Storage stability: The adhesive of each example was stored at room temperature for 24 hours, and the change in viscosity was examined and evaluated according to the following criteria. ：: Little increase in viscosity was observed. ×: Remarkable increase in viscosity was observed.

[0062]

[Table 1]

[0063]

[Table 2]

[0064]

The adhesive of the present invention has no problem of generation of oven fume, has good coating workability, does not cause a large decrease in viscosity upon heating, so that wicket abrasion does not occur, and the adhesive is wound into a coil. The cured state of the adhesive layer in a polyester film having an adhesive layer does not change significantly due to aging, and a coil showing good laminating properties can be produced immediately after winding, and is a thermosetting adhesive for a polyester film-laminated metal plate. It is suitable as an agent.

Claims (3)

[Claims] (A) a number average molecular weight of 4,000 to 4
A hydroxyl group-containing polyester resin having a polyisocyanate compound having a hydroxyl group (OH) in the polyester resin and an isocyanate group (NCO) in the polyisocyanate compound having an (OH / NCO) equivalent ratio of
A urethane-modified polyester resin having a number average molecular weight of 20,000 to 100,000 and a weight average molecular weight in the range of 80,000 to 200,000, and (B) A) a thermosetting adhesive for a polyester film-laminated metal plate, which comprises a blocked polyisocyanate compound. 2. A white pigment is further added in an amount of 50 to 30 parts by weight based on 100 parts by weight of the total amount of the urethane-modified polyester resin (A) and the blocked polyisocyanate compound (B).
The adhesive according to claim 1, wherein the adhesive is contained in an amount of 0 part by weight. 3. The thermosetting adhesive according to claim 1,
A method for producing a polyester film-laminated metal plate, comprising sandwiching between a polyester film and a metal plate, and then heating to cure the adhesive.