JP2007169548A - Adhesive composition for plastic film laminated metal plate - Google Patents

Abstract

An object of the present invention is to provide a thermosetting plastic film laminated metal plate adhesive composition which is excellent in blocking resistance, adhesion and storage stability and can be suitably used for heat lamination of a film and a metal plate. .
A polyester resin (A) having a phosphate ester group and a hydroxyl group, for example, a hydroxyl group and a phosphate group in a hydroxyl group-containing polyester resin (a1) obtained by a condensation reaction of a polyvalent carboxylic acid and a polyhydric alcohol. And a polyester resin obtained by condensing a phosphoric acid group in the compound (a2) having a phosphoric ester group, and an isocyanate group of a polyisocyanate (b1) such as a block polyisocyanate (B), for example, an aliphatic diisocyanate compound An adhesive composition for a plastic laminate metal plate, containing a compound obtained by blocking the above with a blocking agent (b2).
[Selection figure] None

Description

  The present invention relates to a thermosetting plastic excellent in blocking resistance, adhesion and stability over time, comprising a polyester resin having a phosphate ester group and a hydroxyl group and a block polyisocyanate on at least one surface of a plastic film. The present invention relates to an adhesive composition for film-laminated metal plates.

  Laminated steel sheets in which a plastic film with a plain or printed surface is bonded to the steel sheet surface can be made cheaper than conventional metal coating, and are used as home appliances, heating equipment, interior building materials, equipment and the like. This type of laminated steel sheet is manufactured by providing an adhesive layer on a metal material or by laminating an adhesive layer on a plastic film so that the printed surface is on the adhesive layer side.

  For example, a hydroxyl group-containing polyester resin having a number average molecular weight of 4,000 to 40,000 and a blocked polyisocyanate compound as an adhesive for bonding a plastic film to a metal material in order to improve adhesion to a can material. Furthermore, a thermosetting adhesive in which a phosphate group-containing resin is further combined is known (for example, see Patent Document 1).

  However, in the thermosetting adhesive described in Patent Document 1, the phosphoric acid group contained in the phosphoric acid group-containing resin serves as a reaction catalyst between the hydroxyl group of the polyester resin and the blocked block polyisocyanate compound. There is a problem of lowering the storage stability of the resin, and adhesion and blocking resistance are not always sufficient, and improvement is desired.

  As the thermosetting adhesive, in order to improve not only adhesion but also blocking resistance, phosphoric acid is added directly to the main component, hydroxyl group-containing polyester resin, instead of adding phosphoric acid-containing resin. However, it is very difficult to obtain a high-molecular-weight phosphoric acid-modified polyester resin because it becomes easy to gel when a phosphoric acid compound is added to the polyester resin. Instead of adding phosphoric acid directly to the hydroxyl group-containing polyester resin, it is considered that a method using the phosphate group-containing resin in combination with the main agent is adopted.

JP 2002-256247 A

  An object of the present invention is to provide a thermosetting plastic film laminated metal plate adhesive composition excellent in blocking resistance, adhesion and storage stability.

  As a result of intensive studies to solve the above-mentioned problems, the present inventor has found that a phosphoric acid ester compound as a hydroxyl group-containing polyester resin in an adhesive composition for a plastic film laminated steel sheet containing a hydroxyl group-containing polyester resin and a block polyisocyanate By using a hydroxyl group-containing polyester resin modified with a thermosetting plastic film laminated metal plate adhesive composition excellent in blocking resistance, adhesion (particularly adhesion during lamination) and storage stability. The present inventors have found that this can be done and have completed the present invention.

  That is, the present invention provides an adhesive composition for a plastic film laminated metal plate, comprising a polyester resin (A) having a phosphate ester group and a hydroxyl group, and a block polyisocyanate (B). is there.

  The adhesive composition for a plastic film laminated metal plate of the present invention (hereinafter abbreviated as an adhesive composition) is excellent in blocking resistance, adhesion and storage stability. It can be suitably used for thermal lamination.

The polyester resin (A) having a phosphate ester group and a hydroxyl group used in the present invention includes, for example, a hydroxyl group in a hydroxyl group-containing polyester resin (a1) obtained by condensation reaction of a polyvalent carboxylic acid and a polyhydric alcohol, and phosphoric acid. It is obtained by condensing a phosphate group in the compound (a2) having a group and a phosphate ester group. As the phosphoric acid ester groups of the polyester resin (A) having a phosphoric acid ester group and a hydroxyl group, for example, the general formula _{[-OPO (OR 1) (OR 2} ), wherein _R 1, _{R 2} are each Independently, it represents a phenyl group or an alkyl group having 1 to 20 carbon atoms. In particular, it is preferable that R ₁ and R ₂ in the general formula are both alkyl groups having 2 to 10 carbon atoms.

  Examples of the polyvalent carboxylic acid include phthalic acid, isophthalic acid, terephthalic acid, succinic acid, maleic acid, itaconic acid, fumaric acid, tetrahydrophthalic acid, hexahydrophthalic acid, methyltetrahydrophthalic acid, adipic acid, and sebacic acid. , Azelaic acid, "hymic anhydride" [manufactured by Hitachi Chemical Co., Ltd .; "hymic anhydride" is a registered trademark of the same company. ], Trimellitic acid, methylcyclohexentricarboxylic acid, pyromellitic acid, and their anhydrides; dimer acids derived from various unsaturated fatty acids, etc. Of course, these polycarboxylic acids are usually It is used individually or in mixture of 2 or more types.

  Examples of the polyhydric alcohol include ethylene glycol, polyethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, polypropylene glycol, 1,3-butanediol, 2,3-butanediol, 1,4-butanediol, 1, 5-pentanediol, 1,6-hexanediol, 1,4-cyclohexanedimethanol, 2,2-dimethyl-1,3-propanediol (neopentyl glycol), 2,2-dialkyl-1,3-propanediol Diols having an alicyclic structure such as 2,4,4-trimethyl-1,3-pentanediol, butylene glycol, hydrogenated bisphenol A; an adduct of bisphenol A with ethylene oxide, an adduct of bisphenol A with propylene oxide What dihydric alcohols; glycerin, trimethylolethane, trimethylolpropane, polyhydric alcohols such as pentaerythritol, and tris isocyanurate.

  In addition, a polyhydric alcohol having a carboxyl group may be used as the polyhydric alcohol, and examples thereof include dimethylolpropionic acid, dimethylolbutanoic acid, and diphenolic acid.

  The condensation reaction of a polyvalent carboxylic acid and a polyhydric alcohol can be obtained according to various synthesis methods. For example, a polyvalent carboxylic acid and a polyhydric alcohol are added together to form a condensation (ester A synthesis method is generally used.

  In addition, in the condensation reaction of polyvalent carboxylic acid and polyhydric alcohol, if a trivalent or higher carboxylic acid or alcohol is used, the resulting condensate has a branched structure. Considering the crosslinking reactivity with the blocked isocyanate (B) and the adhesion performance, a condensate having a branched structure is more preferable than a linear condensate.

  In carrying out such a condensation reaction, an inert solvent azeotropic with water, such as xylene, may be added.

  Examples of preferable compounds (a2) having a phosphate group and a phosphate ester group used in the production of a polyester resin (A) having a phosphate ester group and a hydroxyl group include dimethyl phosphate, diethyl phosphate, diisopropyl phosphate. , Dialkyl phosphates such as dibutyl phosphate, dioctyl phosphate, di-2-ethylhexyl phosphate and diisodecyl phosphate.

  The amount of the compound (a2) having a phosphoric acid group and a phosphoric acid ester group is such that an adhesive composition having excellent water resistance, retort resistance and laminate adhesion can be obtained. (A1) It is preferable that it is 0.2-3 weight part with respect to 100 weight part, and it is more preferable that it is 0.4-2.5 weight part.

  About the solid content hydroxyl value of the polyester resin (A) having a phosphate ester group and a hydroxyl group used in the present invention, a blending ratio of the polyvalent carboxylic acid and the polyhydric alcohol used when obtaining the hydroxyl group-containing polyester resin (a1). In particular, since an adhesive composition excellent in hot water resistance and reactivity with blocked isocyanate is obtained, it is preferably 2.5 to 10 mgKOH / g, more preferably 5 to 8 mgKOH / g. preferable.

  In addition, the number average molecular weight of the polyester resin (A) having a phosphate ester group and a hydroxyl group has an appropriate viscosity, and an adhesive composition excellent in reactivity with blocked isocyanate and blocking resistance can be obtained. Therefore, it is preferably 5,000 to 40,000, and more preferably 8,000 to 25,000.

  Furthermore, the glass transition temperature (hereinafter referred to as Tg) of the phosphate ester-modified polyester resin (A) is determined by the blending ratio of the polyvalent carboxylic acid and the polyhydric alcohol used when obtaining the hydroxyl group-containing polyester resin (a1). In particular, since an adhesive composition that is excellent in blocking resistance and adhesion and relatively easy to reduce the amount of solvent is obtained, it is preferably −10 to 40 ° C., and preferably 0 to 30 ° C. Is more preferable. Tg was measured using a differential scanning calorimeter (DSC).

  The blocked polyisocyanate (B) used in the present invention is a compound obtained by blocking the isocyanate group of the polyisocyanate (b1) with a blocking agent (b2), and the phosphoric acid is formed by blocking the isocyanate group. Since the reaction between the ester group and the polyester resin (A) having a hydroxyl group is suppressed, a stable adhesive composition can be obtained even with one liquid.

  Examples of the polyisocyanate (b1) include aliphatic polyisocyanate compounds such as hexamethylene diisocyanate, isopropylene diisocyanate, methylene diisocyanate, trimethylhexamethylene diisocyanate, xylylene diisocyanate; isophorone diisocyanate, methylcyclohexane diisocyanate, lysine diisocyanate, cyclohexane. Alicyclic polyisocyanate compounds such as -1,4 diisocyanate; tolylene diisocyanate, 1,5-naphthylene diisocyanate, 4,4'-diphenylmethane diisocyanate, 4,4'-diphenyldimethylmethane diisocyanate, 4,4'- Dibenzyl diisocyanate, dialkyldiphenylmethane diisocyanate, 1,3'-Fe Range isocyanate, 1,4'-phenylene diisocyanate, triphenylmethane-4,4 ', 4 "-triisocyanate, 1,3,5-triisocyanatebenzene, 2,4,6-triisocyanate toluene, 4,4' -Aromatic polyisocyanate compounds such as dimethyldiphenylmethane-2,2 ', 5,5'-tetraisocyanate; adducts of the aforementioned polyisocyanate compounds with polyhydric alcohols, low molecular weight polyester resins or water, or the aforementioned Examples thereof include cyclized polymers of polyisocyanate compounds, and further, isocyanate / biuret compounds, etc. Among these polyisocyanates (b1), aliphatic diisocyanate compounds are preferred, hexamethylene diisocyanate, isophorone diisocyanate. Theft is more preferable.

  The blocking agent (b2) can be freely selected from various blocking agents according to the thermosetting conditions of the adhesive composition for plastic film laminated steel sheets of the present invention, but involves a high-temperature baking step. In order to improve stability at room temperature, it is important to set the dissociation temperature to 100 to 200 ° C., for example, phenol blocking agents such as phenol, cresol, xylenol; ε-caprolactam, δ-valero Lactam blocking agents such as lactam, γ-butyrolactam, β-propiolactam; methanol, ethanol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, tert-butyl alcohol, ethylene glycol monoethyl ether, ethylene glycol mono Butyl ether, diethylene Alcohol blocking agents such as coal monoethyl ether and benzyl alcohol; oxime blocking agents such as formamidoxime, acetaldoxime, acetoxime, methyl ethyl ketoxime, diacetyl monooxime, benzophenone oxime, cyclohexanone oxime; dimethyl malonate, malonic acid Examples include active methylene blocking agents such as diethyl, ethyl acetoacetate, methyl acetoacetate, and acetylacetone.

  Among these blocking agents (b2), there is no dissociation of the blocking agent (b2) in the solvent drying step of the adhesive, and an adhesive composition having excellent adhesion during high-temperature baking can be obtained. Particularly preferred are blocking agents having a temperature of 120 to 150 ° C., such as methyl ethyl ketoxime and acetoxime.

  Blocking of the polyisocyanate (b1) with the blocking agent (b2) can be easily performed, for example, by mixing the polyisocyanate (b1) and the blocking agent (b2).

  As content of the polyester resin (A) which has a phosphate ester group and a hydroxyl group in the adhesive composition of this invention, and block polyisocyanate (B), it is phosphate ester modification | denaturation with respect to a total of 100 weight part of these two components. The polyester resin (A) is preferably 80 to 99 parts by weight, and the block polyisocyanate (B) is preferably 1 to 20 parts by weight. Among them, the phosphate ester-modified polyester resin (A) is 85 to 97 parts by weight, and the block poly The isocyanate (B) is more preferably 3 to 15 parts by weight.

  Further, the adhesive composition of the present invention has a white color in order to give a white color in addition to the above-described phosphate ester-modified polyester resin (A) and block polyisocyanate (B) having a phosphate group and a hydroxyl group. Pigments can be added.

  Examples of the white pigment include titanium oxide, zinc oxide, and lead white. In general, titanium oxide is preferable.

  The average particle diameter of the white pigment is preferably 0.2 to 0.4 μm, and more preferably 0.25 to 0.35 μm because of excellent pigment dispersibility and hiding properties.

  The white pigment is used in an amount of usually 30 to 200 parts by weight, preferably 50 to 150 parts by weight, based on a total of 100 parts by weight of the polyester resin (A) having a phosphate ester group and a hydroxyl group and the block polyisocyanate (B). Part.

  The adhesive composition of the present invention is usually blended with an organic solvent for the purpose of further improving the coating workability, and further, for example, a curing catalyst, an epoxy resin, an anti-blocking agent, if necessary to improve various physical properties. , A colorant (excluding the white pigment), a lubricity-imparting agent, a silane coupling agent, an antifoaming agent, an antistatic agent, and the like can be appropriately blended.

  The organic solvent used in the adhesive composition of the present invention is not particularly limited, but is usually methyl acetate, butyl acetate, butyl acetate, ethylene glycol monoethyl ether acetate, which is used in paints or adhesives, Ester solvents such as ethylene glycol monobutyl ether acetate and ethylene glycol monoethyl ether acetate; ketone solvents such as acetone, methyl ketyl ketone, methyl isobutyl ketone, diisobutyl ketone and cyclohexanone; aromatic hydrocarbons such as toluene and xylene One or more of these can be appropriately selected and used.

  The curing catalyst is blended to promote the reaction between the polyester resin (A) having a phosphate ester group and a hydroxyl group and the blocked polyisocyanate (B). For example, tin octylate, dibutyltin di ( Organometallic catalysts such as 2-ethylhexanoate), dioctyltin di (2-ethylhexanoate), dibutyltin dilaurate, dibutyltin oxide, dioctyltin oxide and lead 2-ethylhexanoate are preferably used. . When the curing catalyst is blended, the blending amount is usually 0.01 to 5 with respect to a total of 100 parts by weight of the polyester resin (A) having a phosphate ester group and a hydroxyl group and the block polyisocyanate (B). Within the range of parts by weight is preferred.

  Examples of the epoxy resin include fats such as ethylene glycol, propylene glycol, hexanediol, neopentyl glycol, trimethylol ethane, trimethylol propane, pentaerythritol, glycerin, diglycerin, sorbitol, spiroglycol, hydrogenated bisphenol A and the like. Diglycidyl ether type epoxy resin of aromatic polyol; poly (methyl) glycidyl ether type epoxy resin of aromatic polyhydroxy compound such as catechol, resorcinol, hydroquinone, bisphenol A, bisphenol F, bisphenol S, bisphenol AD; Diglycidyl ether type epoxy resins of polyols such as ethylene oxide or propylene oxide adducts of polyhydroxy compounds;

Polyglycidyl ether type epoxy resin of polyether polyol such as polyethylene glycol, polypropylene glycol, polytetramethylene glycol; bis (3,4-epoxycyclohexylmethyl) adipate, 3,4-epoxycyclohexylmethyl-3 ', 4'-epoxy Cycloaliphatic polyepoxy resin such as cyclohexyl carboxylate; polyglycidyl ester type of aliphatic or aromatic polycarboxylic acid such as propanetricarboxylic acid, butanetetracarboxylic acid, adipic acid, phthalic acid, terephthalic acid, trimellitic acid, etc. Epoxy resin; bisepoxy resin of hydrocarbon diene such as butadiene, hexadiene, octadiene, dodecadiene, cyclooctadiene, α-pinene, vinylcyclohexene, etc .; polybutadiene Diene polymer epoxy resin such as polyisoprene; glycidylamine epoxy resin using glycidylamine such as tetraglycidyldiaminodiphenylmethane, tetraglycidylbisaminomethylcyclohexane, diglycidylaniline, tetraglycidylmetaxylylenediamine; And epoxy resins containing a heterocyclic ring such as hydantoin.

  Furthermore, examples of these epoxy resins that are commercially available include, for example, epoxy resins derived from bisphenol A. Typical examples of these are “Epicron 850, 860, 1050, 1055”. Or 2055 "(Dainippon Ink Chemical Co., Ltd. product)," Epicoat 828, 834, 1001, 1002, 1004 or 1007 "(Japan Epoxy Resin Co., Ltd. product). Of course, these epoxy resins may be used alone or in combination of two or more.

  The number of epoxy groups contained in one molecule of the epoxy resin is determined after the reaction between the polyester resin (A) having a phosphate ester group and a hydroxyl group, the crosslinking reaction, and the polyester resin (A) having a phosphate ester group and a hydroxyl group. Since an adhesive composition having a good cross-linking reaction between the generated hydroxyl group derived from the epoxy group and the blocked isocyanate (B) and excellent in blocking resistance and adhesiveness is obtained, an average of 1.1 to 2 It is preferable that it is 2 and it is more preferable that it is two.

  The number average molecular weight (Mn) of the epoxy resin is excellent in adhesive strength upon contact with hot water, and an adhesive composition having an appropriate viscosity and excellent paintability is obtained. It is preferable that it is, and it is more preferable that it is 500-4,000.

  The anti-blocking agent is blended in order to impart blocking resistance to the coating surface of a plastic film having a coating film of the adhesive composition, and the laminated film for lamination coated with the adhesive composition is coiled. It is added to prevent blocking during smooth winding. Examples of the anti-blocking agent include transparent inorganic pigments such as precipitated barium sulfate and silica, and fine particles having an average particle diameter of 5 μm or less are preferable. The blending amount is 1 to 20 parts by weight in the case of precipitated barium sulfate with respect to a total of 100 parts by weight of the polyester resin (A) having a phosphate ester group and a hydroxyl group and the blocked polyisocyanate (B), in the case of silica. About 0.1 to 2 parts by weight is desirable. The improvement in blocking resistance is manifested by an increase in apparent glass transition temperature due to the dispersion of the antiblocking agent and an increase in coating surface roughness. Examples of other antiblocking agents include polyethylene, Teflon (registered trademark), and various coupling agents.

  The colorant is used for imparting high designability to the film of the adhesive composition, but can also be used in combination with the white pigment. Furthermore, the colorant can also be used as an antiblocking agent. The added amount of the colorant is desirably 50 to 200 parts by weight with respect to 100 parts by weight of the solid content of the adhesive composition. In addition to these, various pigments such as bright pigments such as aluminum powder, dyes, and the like can also be used as the colorant. Any of these colorants can be selected in accordance with the color tone.

  The lubricity-imparting agent is blended to impart lubricity to the film surface of the adhesive composition, and for smoothly winding the plastic film for laminating with the adhesive composition applied in a coil shape. Also, it is blended for the purpose of preventing the adhesive layer surface from being damaged when the coil is unwound. 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 wax such as carnauba wax and water wax; microcrystalline wax, silicon wax, Mention may be made of waxes such as fluorine-based waxes. When a lubricity imparting agent is blended, the blending amount is usually 0.01 with respect to a total of 100 parts by weight of the polyester resin (A) having a phosphate ester group and a hydroxyl group and the block polyisocyanate (B). The range of 10 to 10 parts by weight is preferred.

The dry coating amount of the adhesive composition of the present invention is not particularly limited. However, since the continuous uniform coating property and the solvent detachability after coating are improved and the workability is improved, 0.5 to 20.0 g / m. ² is preferable, and 1.2 to 13.0 g / m ² is more preferable.

  As the metal plate for laminating the plastic film coated with the adhesive composition of the present invention, various steel plates, for example, sheet-shaped or coil-shaped steel plates, steel foil, iron foil, and surface treatment were applied to these metal plates. However, an aluminum plate can be used as the metal plate other than these steel plates. Among the steel sheets, the upper layer is a chromium hydrated oxide, the lower layer is an electrolytic chromic acid-treated steel sheet having a two-layer structure of chromium metal, ultrathin tin plating, nickel plated steel sheet, galvanized steel sheet, chromium hydrated oxide coated steel sheet A steel sheet treated with phosphate-treated chromate is more preferred. Although it does not specifically limit as a plastic film which coats the adhesive composition of this invention, A polyethylene terephthalate (PET) film, a polyethylene-type film, a polyvinyl chloride-type film etc. are mentioned.

  An example of a method of laminating a plastic film coated with the adhesive composition of the present invention on a metal plate is shown. First, the adhesive composition is uniformly applied to a plastic film or a metal plate so that the dry film thickness is about 2 μm, and the organic solvent is evaporated. The plastic film to be used may be one that has been subjected to a printing process in advance. Next, the plastic film and the metal plate are subjected to thermocompression bonding (thermocompression bonding by a heating roll heat transfer system) using a heating roll so as to reach a temperature of 180 to 250 ° C. through the adhesive composition, and then cooled. The cooling may be performed by either rapid cooling or slow cooling. In the adhesive composition of the present invention, adhesive force appears due to heat at the time of lamination, but high performance can be obtained by heat activation treatment such as reheating at 150 to 250 ° C, preferably 180 to 220 ° C. In addition, as a method of heating the metal plate and the plastic film at the time of laminating, there are various hot air heat transfer methods, resistance heating methods, induction heating methods, etc. in addition to the heating roll heat transfer method described above. However, when considering the equipment cost and simplification of the equipment, the heating roll heat transfer system is preferable. The plastic film-laminated steel sheet thus obtained is excellent in design properties, processing corrosion resistance, and processing adhesion, and can be used for various applications.

  Hereinafter, the present invention will be described more specifically with reference to Reference Examples, Examples and Comparative Examples, but the present invention is not limited thereto. The parts and% in the examples are the rate of increase in the viscosity of the adhesive composition (%) in the evaluation of storage stability and the ratio (%) of the peeled area of the film in the evaluation of processability by the DuPont impact test. All are by weight except for the above.

Reference Example 1 [Preparation of Polyester Resin (A) Having Phosphate Ester Group and Hydroxyl Group]
In a reaction kettle equipped with a stirrer, a rectifying column and a thermometer, 88.9 parts of ethylene glycol, 210.3 parts of neopentyl glycol, 121.0 parts of 1,6-hexanediol, 9.0 parts of trimethylolpropane, Blend 345.4 parts of terephthalic acid, 230.5 parts of isophthalic acid and 157.7 parts of adipic acid, add 31 parts of xylene for refluxing, gradually heat to 260 ° C, and hold at 240 ° C for 5 hours. Then, an esterification reaction was carried out while dehydrating until the solid content hydroxyl value reached 5 mgKOH / g to obtain a hydroxyl group-containing polyester resin. Subsequently, “DP-8” (di-2-ethylhexyl phosphate, manufactured by Daihachi Chemical Industry Co., Ltd.), which is a compound having a phosphate group and a phosphate ester group at 220 ° C., to the obtained hydroxyl group-containing polyester resin. 20.0 parts were added, and the addition reaction was carried out until the solid content hydroxyl value reached 3 mgKOH / g. After completion of the addition reaction, 1000 parts of toluene was charged to obtain a solution of a polyester resin (A-1) having a solid content hydroxyl value of 3.6 mgKOH / g and a non-volatile content of 50.1% phosphate group and hydroxyl group. The glass transition temperature (Tg) of this polyester resin (A-1) was 15 ° C. (Tg was measured using DS Instruments Q-100, manufactured by TA Instruments. Subsequent Tg was also measured using the same device), number average. The molecular weight (Mn) was 20,000.

Reference example 2 (same as above)
In the same reaction kettle as in Reference Example 1, 88.5 parts of ethylene glycol, 208.8 parts of neopentyl glycol, 120.6 parts of 3-methyl-1,5-pentanediol, 15.0 parts of trimethylolpropane, terephthalic acid 343.4 parts, 229.9 parts of isophthalic acid and 157.2 parts of adipic acid were added, and 31 parts of xylene for reflux was further added. After gradually heating to 260 ° C., the mixture was held at 240 ° C. for 5 hours, While dehydrating, an esterification reaction was performed until the solid content hydroxyl value reached 5 mgKOH / g to obtain a hydroxyl group-containing polyester resin. Subsequently, “DP-4” (dibutyl phosphate manufactured by Daihachi Chemical Industry Co., Ltd.), 9.0 parts, which is a compound having a phosphate group and a phosphate ester group at 220 ° C. to the obtained hydroxyl group-containing polyester resin. And the addition reaction was carried out until the solid content hydroxyl value reached 3.5 mgKOH / g. After completion of the addition reaction, 1000 parts of toluene was charged to obtain a solution of a polyester resin (A-2) having a solid content hydroxyl value of 3.9 mgKOH / g and a nonvolatile content of 50.2% and having a phosphate group and a hydroxyl group. This polyester resin (A-2) had a glass transition temperature (Tg) of 13 ° C. and a number average molecular weight (Mn) of 12,000.

Reference Example 3 (Preparation of polyester resin having phosphoric acid group and hydroxyl group used as main agent)
In the same reaction kettle as in Reference Example 1, 88.5 parts of ethylene glycol, 208.8 parts of neopentyl glycol, 120.6 parts of 3-methyl-1,5-pentanediol, 15.0 parts of trimethylolpropane, terephthalic acid 343.4 parts, 229.9 parts of isophthalic acid and 157.2 parts of adipic acid were added, and 31 parts of xylene for reflux was further added. After gradually heating to 260 ° C., the mixture was held at 240 ° C. for 5 hours, While dehydrating, an esterification reaction was performed until the solid content hydroxyl value reached 3 mgKOH / g to obtain a hydroxyl group-containing polyester resin. Next, an addition reaction was attempted by adding 0.7 part of 85% phosphoric acid to the obtained hydroxyl group-containing polyester resin at 220 ° C., but gelation was performed to obtain a polyester resin having a target phosphate group and hydroxyl group. I couldn't.

Reference Example 4 (Preparation of a polyester resin having a phosphate group and a hydroxyl group used in combination with the main agent)
In the same reaction kettle as in Reference Example 1, 90.0 parts of ethylene glycol, 212.4 parts of neopentyl glycol, 122.7 parts of 3-methyl-1,5-pentanediol, 15.3 parts of trimethylolpropane, terephthalic acid 338.0 parts, 226.3 parts of isophthalic acid and 154.7 parts of adipic acid were added, and 31 parts of xylene for refluxing was further added. After gradually heating to 260 ° C., the mixture was held at 240 ° C. for 5 hours, While dehydrating, an esterification reaction was performed until the solid content hydroxyl value was 3.5 mgKOH / g to obtain a hydroxyl group-containing polyester resin. Subsequently, 30.0 parts of 85% phosphoric acid was added to the obtained hydroxyl group-containing polyester resin at 220 ° C., and an addition reaction was performed until the solid content hydroxyl value became 30.0 mgKOH / g. After completion of the addition reaction, 1000 parts of toluene was charged to obtain a solution of a polyester resin (a-1) having a solid content hydroxyl value of 30.5 mg KOH / g and a non-volatile content of 50.3% having a phosphate group and a hydroxyl group. The polyester resin (a-1) having a phosphate group and a hydroxyl group had a glass transition temperature (Tg) of 10 ° C. and a number average molecular weight (Mn) of 4,000.

Reference Example 5
In the same reaction kettle as in Reference Example 1, 88.5 parts of ethylene glycol, 208.8 parts of neopentyl glycol, 120.6 parts of 3-methyl-1,5-pentanediol, 15.0 parts of trimethylolpropane, terephthalic acid 343.4 parts, 229.9 parts of isophthalic acid and 157.2 parts of adipic acid were added, and 31 parts of xylene for reflux was further added. After gradually heating to 260 ° C., the mixture was held at 240 ° C. for 5 hours, While dehydrating, an esterification reaction was performed until the solid content hydroxyl value reached 3 mgKOH / g to obtain a hydroxyl group-containing polyester resin. Subsequently, 1000 parts of toluene was added to the obtained hydroxyl group-containing polyester resin, and the polyester had a hydroxyl group with a solid content hydroxyl value of 3.6 mgKOH / g and a nonvolatile content of 50.3% but had neither a phosphate group nor a phosphate ester group. A solution of resin (a-2) was obtained. This polyester resin (a-2) had a glass transition temperature (Tg) of 16 ° C. and a number average molecular weight (Mn) of 17,000.

Example 1
“VESTANAT B1370” which is a blocked isocyanate compound (block isophorone diisocyanate manufactured by Huls Japan, non-volatile content: 60%) with respect to 200 parts of a solution of the polyester resin (A-1) having a phosphate ester group and a hydroxyl group. 3 parts and 0.1 part of “Neostan U-200” (Nitto Kasei Co., Ltd. dibutyltin compound) as a catalyst are mixed and dispersed, and bonded using a diluent of methyl ethyl ketone / toluene (weight ratio) = 1/1. The adhesive composition (Z-1) was prepared so that the agent solid content was 35%.

The adhesive composition (Z-1) was applied to a polyethylene terephthalate film having a thickness of 12 μm with a bar coater so that the dry weight was 2 g / m ² , and dried at 100 ° C. for 30 seconds. The obtained coated film was laminated so that the adhesive composition coated surface was in contact with the tin-free steel plate (TFS plate) and heated to 180 ° C. at a rate of 3.6 m / min, 3 MPa. After thermocompression bonding with pressure, heat treatment was performed at 220 ° C. for 2 minutes in a gas oven to prepare a polyethylene terephthalate film laminated steel sheet. Evaluation of storage stability of adhesive composition (Z-1), blocking resistance of the obtained coating film, and laminate appearance, adhesion, workability and hot water resistance using the obtained laminated steel sheet The evaluation was carried out by the following evaluation methods. The evaluation results are shown in Table 1.

(Storage stability)
The adhesive composition (Z-1) was stored overnight at room temperature, and the change in viscosity was evaluated according to the following evaluation criteria.
Evaluation criteria A: The rate of increase in viscosity is less than 5%.
A: The rate of increase in viscosity is 5% or more and less than 10%.
Δ: Increase rate of viscosity is 10% or more and less than 20%.
X: The rate of increase in viscosity is 20% or more (x).

(Blocking resistance)
The adhesive composition layer surface of the coated film obtained by drying at 100 ° C. for 30 seconds and the untreated surface of another PET film are in contact with each other, and a pressure of 0.4 MPa is applied to the temperature. The film laminate after storage for 3 days in a room at 32 ° C. and a humidity of 60% RH is cut to a width of 80 mm, and peeling between the surface of the adhesive composition layer of the coated film and the untreated surface of another PET film The strength (g / 80 mm) was measured under the conditions of a tensile speed of 1,000 mm / min and 180 °, and evaluated according to the following evaluation criteria.
Evaluation criteria A: Peel strength is less than 10 g / 80 mm.
○: Peel strength is 10 g / 80 mm or more and less than 20 g / 80 mm.
Δ: The peel strength is 20 g / 80 mm or more and less than 50 g / 80 mm.
X: Peel strength is 50 g / 80 mm or more.

(Laminate appearance)
With respect to the laminated portion of the obtained laminated steel sheet, the presence or absence of bubbles, the presence or absence of wrinkles, etc. were visually evaluated according to the following evaluation criteria.
Evaluation criteria A: No generation of bubbles and no wrinkles on the film.
○: Although there is a slight generation of bubbles, there is no film wrinkle.
Δ: There are some wrinkles of the film along with the generation of bubbles.
X: There is a wrinkle of the film along with the generation of bubbles.

(Adhesion): Cross-cut cellophane adhesive tape peeling test The obtained laminated steel sheet was retorted at 125 ° C. for 30 minutes, and the laminated film part of the laminated steel sheet before and after retorting reached the steel sheet surface with a knife, respectively. Create 100 1mm x 1mm squares with cuts, apply cellophane adhesive tape to the surface, and record the number of squares left without peeling when instantly peeled. Evaluated by criteria.
Evaluation criteria A: The number of cells remaining without peeling is 100.
○: The number of cells remaining without peeling is 90 to 99.
(Triangle | delta): The number of the squares which remained without peeling is 70-89 pieces.
X: The number of grids remaining without peeling is 69 or less.

(Processability): DuPont impact test After impact was applied from the back side of the laminated steel plate (steel plate side) under the conditions of 1/2 inch, 300 g load and 30 cm height, high temperature hot water treatment was performed at 125 ° C for 30 minutes. The adhesion state of the laminate film was evaluated according to the following evaluation criteria.
Evaluation criteria A: No peeling of film.
○: The ratio of the peeled area of the film is less than 2%.
(Triangle | delta): The ratio of the peeling area of a film is 2% or more and less than 5%.
X: The ratio of the peeling area of a film is 5% or more.

(Heat resistant water)
The whitening state of the adhesive layer of the laminated steel sheet after high-temperature hot water treatment at 125 ° C. for 30 minutes was visually observed and evaluated in four stages according to the following evaluation criteria.
A: No generation of bubbles, no film wrinkles, no blisters.
○: Although there are some bubbles, there is no film wrinkles or blisters.
(Triangle | delta): There are some wrinkles and blisters of a film with generation | occurrence | production of a bubble.
X: Along with the generation of air bubbles, there are film wrinkles and blisters.

Example 2
"Sumidur BL3175" which is a blocked isocyanate compound (blocked HDI manufactured by Sumika Bayer Urethane Co., Ltd., 75% non-volatile content) with respect to 200 parts of a solution of a polyester resin (A-2) having a phosphate ester group and a hydroxyl group 26.7 parts and 0.1 parts by weight of “Formate TK-1” (Tinda Catalyst Co., Ltd. manufactured by Takeda Pharmaceutical Co., Ltd.) as a catalyst are mixed and dispersed, and a diluent with methyl ethyl ketone / toluene (weight ratio) = 1/1 is added. An adhesive composition (Z-2) was prepared so that the adhesive solid content was 35%.

  A coated film was produced in the same manner as in Example 1 except that the adhesive composition (Z-2) was used instead of the adhesive composition (Z-1), and further a polyethylene terephthalate film laminated steel sheet was produced. . Evaluation of storage stability of adhesive composition (Z-2), blocking resistance of the obtained coating film, and laminate appearance, adhesion, workability and hot water resistance using the obtained laminated steel sheet The evaluation methods similar to those of Example 1 were used for evaluation. The evaluation results are shown in Table 1.

Example 3
33.3 parts of “VESTANAT B1370” as a blocked isocyanate compound and “Neostan U-200” (Nitto Kasei Co., Ltd.) as a catalyst for 200 parts of a polyester resin (A-1) solution having a phosphate ester group and a hydroxyl group 0.1 parts of dibutyltin compound) and 100 parts by weight of “JR301” (titanium oxide manufactured by Teika Co., Ltd.) as a white pigment are mixed and dispersed using a diluent of methyl ethyl ketone / toluene (weight ratio) = 1/1. An adhesive composition (Z-3) was prepared so that the adhesive solid content was 52%.

A coated film in the same manner as in Example 1 except that the adhesive composition (Z-3) was used in place of the adhesive composition (Z-1) and the dry weight was 10 g / m ^2. Further, a polyethylene terephthalate film laminated steel sheet was prepared. Evaluation of storage stability of adhesive composition (Z-3), blocking resistance of the obtained coating film, and laminate appearance, adhesion, workability and hot water resistance using the obtained laminated steel sheet The evaluation methods similar to those of Example 1 were used for evaluation. The evaluation results are shown in Table 1.

Comparative Example 1
For 20 parts of a solution of a polyester resin (a-1) having a phosphoric acid group and a hydroxyl group, and 180 parts of a solution of a polyester resin (a-2) having a hydroxyl group but having neither a phosphate group nor a phosphate ester group, 26.7 parts of “Sumijoule BL3175”, which is a blocked isocyanate compound, and 0.1 part of “Neostan U-200” as a catalyst are mixed and dispersed, using a diluent of methyl ethyl ketone / toluene (weight ratio) = 1/1. An adhesive composition (z-1) was prepared so that the adhesive solid content was 35%.

  A coated film was produced in the same manner as in Example 1 except that the adhesive composition (z-1) was used in place of the adhesive composition (Z-1), and further a polyethylene terephthalate film laminated steel sheet was produced. . Evaluation of storage stability of adhesive composition (z-1), blocking resistance of the obtained coating film, and laminate appearance, adhesion, workability and hot water resistance using the obtained laminated steel sheet The evaluation methods similar to those of Example 1 were used for evaluation. The evaluation results are shown in Table 1.

Comparative Example 2
With respect to 200 parts of the solution of the polyester resin (a-2) having a hydroxyl group but having neither a phosphate group nor a phosphate ester group, 26.7 parts of “Sumidur BL3175” as a blocked isocyanate compound and “Neostan as a catalyst” Adhesive composition (z-2) so that 0.1 part of U-200 is mixed and dispersed, and the solid content of the adhesive is 35% using a diluent of methyl ethyl ketone / toluene (weight ratio) = 1/1. Was prepared.

A coated film in the same manner as in Example 1 except that the adhesive composition (z-2) was used in place of the adhesive composition (Z-1) and the dry weight was 10 g / m ^2. Further, a polyethylene terephthalate film laminated steel sheet was prepared. Evaluation of storage stability of adhesive composition (z-2), blocking resistance of the obtained coating film, and laminate appearance, adhesion, workability and hot water resistance using the obtained laminated steel sheet The evaluation methods similar to those of Example 1 were used for evaluation. The evaluation results are shown in Table 1.

The adhesive composition for plastic film laminated metal plate of the present invention is excellent in blocking resistance, adhesion and storage stability, and can realize high solidification of the adhesive, and is widely applied to laminated steel sheets. It is possible and greatly contributes to productivity improvement.

Claims (6)

An adhesive composition for a plastic laminate metal plate, comprising a polyester resin (A) having a phosphate ester group and a hydroxyl group, and a block polyisocyanate (B). The adhesive composition for laminated metal plates according to claim 1, wherein the polyester resin (A) is a branched polyester resin having a phosphate group and a hydroxyl group. The polyester resin obtained by using 0.2 to 3 parts by weight of the compound (a2) having a phosphate group and a phosphate ester group with respect to 100 parts by weight of the hydroxyl group-containing polyester resin (a1). 2. The adhesive composition for plastic laminate metal plates according to claim 1, which is a branched polyester resin having a solid content hydroxyl acid value of 2.5 to 10.0 mg KOH / g. The polyester resin (A) contains 80 to 99 parts by weight and the block polyisocyanate (B) contains 1 to 20 parts by weight with respect to 100 parts by weight of the total of the polyester resin (A) and the block polyisocyanate (B). Item 4. The adhesive composition for a plastic laminate metal plate according to any one of Items 1 to 3. Furthermore, the plastic laminate of any one of Claims 1-4 which contains a white pigment 30-200 weight part with respect to a total of 100 weight part of the said polyester resin (A) and block polyisocyanate (B). Adhesive composition for metal plates. It is an adhesive composition for plastic laminate steel plates, The adhesive composition for plastic laminate metal plates according to any one of claims 1 to 5.