WO2008155611A1

WO2008155611A1 - Primer composition

Info

Publication number: WO2008155611A1
Application number: PCT/IB2008/001253
Authority: WO
Inventors: Toshiya Kitamura; Hayato Ishibashi
Original assignee: Basf Coatings Japan Ltd.
Priority date: 2007-06-19
Filing date: 2008-05-15
Publication date: 2008-12-24
Also published as: JP2009001623A

Abstract

The Problem: to provide primer compositions which can form coated primer films with: excellent adhesion to metals such as iron and copper, these metals with plating thereon plated steel sheet, particularly zinc- plated steel sheet; excellent adhesion to topcoat films when polyamide (nylon) resins form topcoat films; and, in particular, excellent properties with regard to gasohol. The Means of Solution : primer compositions containing (A) polyamide-imide resins, (B) solvent- soluble polyamide resins, (C) solvent-insoluble nylon resin beads, (D) epoxy resins and (E) hardeners, characterized in that there are: 10 to 30% by mass of component (A); 5 to 20% by mass of component (B); 59 to 15% by mass of component (C); 10 to 30% by mass of component (D); and 1 to 20% by mass of component (E), per total mass of the solid resin components (A), (B), (C), (D) and (E).

Description

Primer compositions Specification [Technical Field] [0001]

The present invention relates to primer compositions, which can form primer films with: excellent adhesion properties for metals, such as iron and copper or these metals with plating thereon plated steel sheet, particularly for steel sheet plated with zinc; excellent adhesion properties to topcoat films when polyamide (nylon) resins are used as topcoat films; and excellent resistance to solvents, for example, gasoline.

[Background Art]

[0002]

Piping is known (cf., for example, Patent Reference 1) characterized in that it is piping for automobile brake systems, fuel systems, or hydraulic systems, wherein there are layers consisting of external plastic jacket layers, comprising thermoplastic materials, especially polyamide resins, which are extruded onto chromate layers on the internal surfaces of the metal piping. However, there is the drawback with this piping that adhesion is inadequate after immersion in gasohol (denotes gasoline mixed with a low concentration of ethanol, a fuel developed and implemented in the United States and Brazil, with the object of the octane number, reducing the quantities of nitrogen dioxide discharged, and the like) .

[0003]

Surface treatment processes are known for metal piping, as processes for the surface treatment of metal piping (cf. Patent Reference 2), wherein there are formed an intermediate epoxy-based resin layer, comprising epoxy- based resin coatings, whereto anticorrosion pigments have been added, wherein the main ingredients are condensed phosphoric acid salts and magnesium silicate- based compounds, which are formed on chemically treated layers, with the main components of the said chemically treated layers being chromium (III) compounds and phosphoric acid compounds, which are formed on zinc or zinc - nickel plate layers, with the said plated metal layer being formed onto the external skin of metal piping. However, with this process, there is the drawback that, although there is no chromium(VI) during treatment and coating, chromium(III) is contained: they are not chromium-free, which is a safety requirement for marketing; and the drawback that adhesion properties are inadequate after immersion in gasohol .

[0004]

A third process is known (cf., for example Patent Reference 3 ) , wherein a primer coat using a chromium- free surface-treated layer, and/or a commercial polyamide primer is interposed between an aluminum coat and polyamide resin layer, as a connection to a conduit for fluids used in automobiles, especially fuels and hydraulic liquids, comprising a metal internal pipe, an aluminum coat formed on the outer surface of the internal pipe and a polyamide resin layer connected to the aluminum coat. However, there is the drawback that gasohol resistance is inadequate (coated film adhesion test after immersion in gasohol) .

[0005]

A fourth process is known (cf., for example, Patent Reference 4) wherein low temperature hardening and high adhesion may be obtained by adding an epoxy resin to a polyamide-imide resin. However, there is the drawback that the coated films are brittle, so that processing properties with respect to bending are inadequate.

[0006]

Metal object coating processes are known (cf., for example, Patent Reference 5) wherein thermoplastic resin coatings are formed by applying, onto the surfaces of coated metal objects, primer compositions, wherein inorganic corrosion inhibitors are compounded into at least 1 binder component, selected from a group comprising: binder component (A) containing an epoxy resin and an amino resin and/or a phenol resin; binder component (B) containing a polyester resin, epoxy resin and phenol resin; and binder component (C) containing an α-olefin - α, β-ethylenic unsaturated carboxylic acid; and a thermoplastic resin-based coating (any of vinyl fluoride-based coatings, vinylidene fluoride- based coatings or polyamide resin-based coatings) is coated, via the coated primer film layer.

[ 0007 ] [Patent Reference 1] International Patent implication Publication 9-509723

[Patent Reference 2] Japanese Uhexamined Patent implication 2003-194288

[Patent Reference 3] Japanese Uhexamined Patent Application 2003-343767

[Patent Reference 4] Japanese Uhexamined Patent Application 9-302226

[Patent Reference 5] Saikohyσ WO2003-033173 [DISCLOSURE OF THE INVENTION]

[ Problems to be Solved by the Invention] [ 0008 ]

An obj ect of the present invention is to provide primer compositions which can form coated primer films with excellent adhesion to metals such as iron, copper and these metals with plating thereon plated steel sheet , particularly zinc-plated steel sheet , and with excellent adhesion to topcoat films , where polyamide (nylon) resins form topcoat films .

[The Means of Solving the Problems] [0009]

The present inventors, as a result of a series of diligent investigations to solve the above-mentioned problems, achieved the present invention by discovering that the above-mentioned problems are solved by means of primer compositions containing polyamide-imide resins, solvent-soluble polyamide resins, solvent- insoluble nylon resin beads, epoxy resins and hardeners, in specified proportions. That is, the present invention provides primer compositions containing (A) polyamide-imide resins, (B) solvent-soluble polyamide resins, (C) solvent-insoluble nylon resin beads, (D) epoxy resins and (E) hardeners, characterized in that there are the contents: 10 to 30% by mass of component (A) ; 5 to 20% by mass of component

(B) ; 59 to 15% by mass of component (C) ; 10 to 30% by mass of component (D) ; and 1 to 20% by mass of component (E) , per total mass of the solid resin components (A) , (B) , (C) , (D) and (E) . The present invention also provides primer compositions, wherein component (E) in the above-mentioned primer compositions is a phenol resin and/or an amino resin. The present invention further provides primer compositions, wherein the primer compositions are primer compositions which are used as the undercoats for polyamide resin films.

[Effects of the Invention] [0010]

The primer compositions according to the present invention can form coated primer films exhibiting excellent adhesion to metals such as iron, copper and these metals with plating thereon plated steel sheet, particularly to zinc-plated steel sheet and excellent adhesion to topcoat films and, in particular have excellent performance with regard to properties towards gasohol, when polyamides (nylons) form topcoat films.

[Best Mode of Executing the Invention] [0011]

The present invention relates to primer compositions containing polyamide-imide resins, solvent-soluble polyamide resins, solvent-insoluble nylon resin beads, epoxy resins and hardeners.

The resin acid values of the polyamide-imide resin components (A) used according to the present invention are preferably 30 mg KOH/g, more preferably 10 mg

KOH/g. If the acid value exceeds 30 mg KOH/g, the stability when stored at 50⁰C is reduced, which is not preferred.

In addition, the number average molecular weights of the polyamide-imide resin components (A) are preferably

9,000 to 28,000, more preferably 12,000 to 25,000. With number average molecular weights of less than 9,000, the gasohol properties deteriorate and, if 28,000 is exceeded, coating operation properties deteriorate, which is not preferred. It is further preferable that the polyamide-imide resin components (A) are soluble in solvents .

The role of components (A) according to the present invention is to suppress swelling of coated films when immersed in gasohol and to ensure adhesion of coated primer films after gasohol immersion.

[0012]

The processes for the manufacture of the polyamide- imide resins are not especially limited: various manufacturing processes may be cited. The polyamide- imide resins are manufactured by known manufacturing processes, to be specific, by reaction in organic polar solvents of: (a) trivalent or higher polycarboxylic acids, having acid anhydride groups; (b) divalent di- carboxylic acids; (c) aromatic isocyanates or aromatic diamines; and (d) lactams. The proportions of (a) to (d) are, for example, preferably, compounding proportions of (a) and (b) , ratio of equivalent weights, (a) : (b) of 4:6 to 9:1; preferably the proportion of (c) , the ratio of total numbers of carboxyl groups of (a) and (b) and of amine groups is 8 to 16 and preferably the proportion of (d) is 0.1 to 20% by weight versus the total mass of (a) , (b) and (c) . Reactions are carried out by thermal condensation in the temperature range 80° to 150⁰C, in the presence of polar solvents, whilst removing carbon dioxide gas, which is liberated when aromatic diisocyanates are used. Reaction times are appropriately chosen, depending on the scale of the batches and reaction conditions used. [0013]

Examples of the organic polar solvents which may be used are single solvents or combinations of 2 or more of: N-methyl-2-pyrrolidone, N,N-dimethylformamide, N, N- dimethylacetamide, dimethylsulfoxide, γ-butyrolactone, diethylene glycol dimethyl ether and triethylene glycol dimethyl ether; the quantities thereof to use are preferably 1.0 to 5.0 (by mass) times the quantities of polyamide-imide resins formed. After polyamide-imide resin synthesis has been completed, when an aromatic diisocyanate has been used, blocking may be carried out with an agent, such as resin terminal isocyanate groups, and also alcohols, lactams, oximes and the like.

[0014]

Examples of commercial polyamide-imide resins are:

Vylomax HRlINN, Vylomax 13NX, Vylomax 14ET (all manufactured by Toyo Boseki K K); HI-405-30, HPC-5000,

HPC-5010S, HPC-5020, HPC-5030, HPC-6000, HPC-6100, HPC-

7200 and HPC-9000 (all manufactured by Hitachi Kasei

Kogyo K K) .

The polyamide-imide resin components (A) may be used as 1 type individually, or as 2 or more types thereof together.

[0015] The solvent-soluble polyamide resins (B) according to the present invention may be polyamide resins which are soluble in the solvents of the primer compositions; their molecular weights are not especially limited. The role of the solvent-soluble polyamide resin components (B) is to ensure compatibility with the solvent- insoluble nylon resin bead component (C) and to raise coated film strength, by increasing the miscibility of solvent-insoluble nylon resin beads with epoxy resins and hardeners, by ensuring that component (D) and component (E) are miscible.

Examples of the solvent-soluble polyamide resins which may be given are resins which are soluble in solvents from amongst: polyamide 6, from ring-opening polymerization of ε-caprolactam; polyamide 66, from polycondensation of hexamethylenediamine and adipic acid; polyamide 610, from polycondensation of hexamethylenediamine and sebacic acid; polyamide 11, from polycondensation of 11-aminoundecanoic acid; and polyamide 12, from ring-opening polymerization of ω- laurolactam or polycondensation of 12-aminododecanoic acid.

Examples of commercial solvent-soluble polyamide resins which may be used as component (B) are: PA-100, PA- 10OA, PA-102A, PA-200, PA-201, TPAE-12 (all manufactured by Fuji Kasei Kogyo K K) .

The solvent-soluble polyamide resin components (B) may be used as 1 type individually, or as 2 or more types thereof together.

[0016]

The solvent-insoluble nylon resin bead components (C) used according to the present invention may be nylon resin beads which are insoluble in the solvents of the primer compositions. The melting temperatures of the solvent-insoluble nylon resin bead components (C) are preferably 150⁰C or higher, more preferably 170⁰C or higher. With a melting temperature of less than 15O⁰C, there is a tendency for the heat stability of the resins during high temperature baking to be reduced, which is not preferable. In addition, the solvent-insoluble nylon resin bead components (C) are preferably nylon resin beads which are insoluble in solvents such as alcohols, esters and ketones .

The mean particle diameters of the solvent-insoluble nylon resin bead components (C) are preferably 5 to 100 μm, more preferably 10 to 50 μm. With a mean particle diameter of less than 5 μm, there is a tendency for coating viscosities to increase, which is not preferred, and, when 100 μm is exceeded, there is a tendency for storage stability to decrease, which is also not preferred.

The role of the solvent-insoluble nylon resin bead components (C) according to the present invention is to ensure adhesion between coated primer films and topcoat films, particularly coated polyamide resin films.

[0017]

Examples of the solvent-insoluble nylon resin beads which may be given are: polyamide 6, from ring-opening polymerization of ε-caprolactam; polyamide 66, from polycondensation of hexamethylenediamine and adipic acid; polyamide 610, from polycondensation of hexamethylenediamine and sebacic acid; polyamide 11, from polycondensation of 11-aminoundecanoic acid; and polyamide 12, from ring-opening polymerization of ω- laurolactam or polycondensation of 12-aminododecanoic acid. Examples of commercial solvent-insoluble polyamide resins which may be given are: Rilsan Fine Powder D30 Naturell, Rilsan Fine Powder D40 Naturell, Rilsan Fine Powder D50 Naturell, Orgasol 1002DNATl, Orgasol 1002ES4NAT1, Orgasol 2002ES4NAT3, Orgasol 2002ES3NAT3, Orgasol 3501EDXNAD1, Orgasol 3502DNAD1 (all manufactured by Alkema Company), SNP Powder-13, SNP Powder-19 (both manufactured by Metal Color Company) and A1020LP (manufactured by Unichika Company) . The solvent-insoluble nylon resin bead components (C) may be used as 1 type individually, or as 2 or more types thereof together.

[0018] The epoxy values of the resin components (D) used according to the present invention are preferably 30 to 250 mg KOH/g, more preferably 50 to 130 mg KOH/g. If the epoxy value exceeds 250 mg KOH/g, there is a tendency for adhesion to plated steel sheet to deteriorate and, with less than 30 mg KOH/g, there is a tendency for coating operation properties to deteriorate.

The role of the epoxy resin components (D) according to the present invention is to ensure that there is adhesion between coated primer films and plated steel sheet .

[0019]

The epoxy resins used according to the present invention preferably have 2 or more epoxy groups per 1 molecule, and known conventional liquid or solid epoxy resins may be used, without any special limit. In addition, when solid epoxy resins are employed, the said resins are used by dissolving or dispersing them in solvents or dispersion-capable organic solvents.

[0020]

Examples of commercial epoxy resins which may be given are bisphenol A/epichlorohydrin type epoxy resins, such as JERlOOl, JER1002, JER1003, JER1055, JER1004, JER1007

(all manufactured by Japan Epoxy Resins Company) ,

Epotote YD-134, Epotote YD-011, Epotote YD-012, Epotote

YD-013, Epotote YD-014, Epotote YD-017, Epotote YD- 7011R, Epotote YD-907 (all manufactured by Toto Kasei Company), D. E. R662E, D. E. R663UE, D. E. R664U and D. E. R667E (all manufactured by Dow Chemical Company) .

The epoxy resin components (D) may be used as 1 type individually, or as 2 or more types thereof together.

[0021]

The hardener components (E) used according to the present invention are preferably phenol resins and amino resins, which may be used individually or together.

The role of the hardener components (E) according to the present invention is to obtain thermosetting coated films by reaction with the resin components in the compounded resins .

The number average molecular weights of the phenol resins are preferably 300 to 1,500, more preferably 400 to 1,000. With number average molecular weights of less than 300, there is a tendency for the bending properties of hardened coated films to deteriorate and, when 1,500 is exceeded, there is a tendency for the storage stability of coated films at 5O⁰C to deteriorate.

[0022]

Phenol resins are obtained by reactions of phenols and formaldehyde. Examples of the phenols used in order to obtain phenol resins which may be given are: phenols having 1 benzene ring in a molecule, such as phenol, methylphenol, para-ethylphenol, para-n-propylphenol, para-isopropylphenol, para-n-butylphenol, para-ter- tiary-butylphenol, para-tertiary-amylphenol, ortho-cre- sol, /nefca-cresol, para-cresol, para-eyelohexylphenol, para-octylphenol, para-nonylphenol, 3,5-xylenol, resor- cinol and catechol; phenols having 2 benzene rings in a molecule, such as phenyl-ortho-cresol and para-phenyl- phenol; bisphenol A and bisphenol F; these may be used singly or as mixtures of 2 or more thereof. Examples of the formaldehyde forms which may be given are formaldehyde, paraformaldehyde and trioxan.

[0023]

Inorganic acids, organic acids, metal salts of organic acids and the like may be used as catalysts for reactions of the above-mentioned phenols and formaldehyde .

The phenol resins may be resol type phenol resins or novolac type phenol resins. The phenol resins may also, as required, be appropriately modified with natural resins, acrylic resins, polyester resins, or the like. The above-mentioned phenol resins may be used individually or 2 or more thereof may be selected. [ 0024 ]

The weight average molecular weights of the amino resins are preferably 600 to 20,000, more preferably 1,000 to 10,000. With weight average molecular weights of less than 800, there is a tendency for the bending properties of hardened coated films to deteriorate and, when 20,000 is exceeded, there is a tendency for the properties with respect to gasohol to deteriorate, which is not preferred. Examples of amino resins which may be given are methylolated amino resins, such as: melamine resins, urea resins, benzoguanamine resins, acetoguanamine resins, steroguanamine resins, spiroguanamine resins and dicyandiamides; the amino resins may be modified with epoxy resins, acrylic resins, polyester resins, or the like. Melamine resins are preferred from the viewpoint of bending and processing properties. The above-mentioned amino resins may be used singly, or 2 or more thereof may be selected. The hardener components (E) may be used singly, or as 2 or more thereof together.

[0025]

The percentage contents in the primer compositions of component (A) polyamide-imide resins, component (B) solvent-soluble polyamide resins, component (C) solvent-insoluble nylon resin beads, component (D) epoxy resins and component (E) hardeners, are: 10 to 30% by mass of component (A) ; 5 to 20% by mass of component (B) ; 59 to 15% by mass of component (C) ; 10 to 30% by mass of component (D) ; and 1 to 20% by mass of component (E) , per total mass of the solid resin components (A) , (B) , (C) , (D) and (E) .

More preferably, there are: 15 to 22% by mass of component (A) ; 10 to 15% by mass of component (B) ; 50 to 30% by mass of component (C) ; 15 to 25% by mass of component (D) ; and 3 to 13% by mass of component (E) . The total content of components (A) , (B) , (C) , (D) and (E) is made 100%. In addition, solid resin fractions denote the heating residues when measured by the method stated in JIS (Japanese Industrial Standard) K5601-1-2.

[0026]

When there is less than 10% by mass of component (A) , adhesion between coated primer films and topcoats (secondary adhesion) after gasohol immersion deteriorates and, if 30% by mass is exceeded, initial adhesion between coated primer films and topcoats (primary adhesion) deteriorates, which is not preferred.

When there is less than 5% by mass of component (B) , initial adhesion between coated primer films and topcoats (primary adhesion) deteriorates and, if 20% by mass is exceeded, adhesion after gasohol immersion between coated primer films and topcoats (secondary adhesion) deteriorates, which is not preferred. [ 0027 ]

When there is less than 15% by mass of component (C) , primary adhesion between coated primer films and topcoats deteriorates and, if 59% by mass is exceeded, secondary adhesion between coated primer films and topcoats after gasohol immersion deteriorates, which is not preferred. When there is less than 10% by mass of component (D) , adhesion between coated primer films and plated steel sheet deteriorates and, if 30% by mass is exceeded, bending and processing properties deteriorate, which is not preferred. When there is less than 1% by mass of component (E) , adhesion between coated primer films and topcoats after gasohol immersion deteriorates and, if 20% by mass is exceeded, bending and processing properties deteriorate, which is not preferred.

[0028]

Anticorrosion pigments may be compounded into the primer compositions according to the present invention, with the object of increasing corrosion resistance. The corrosion-proofing pigments which may be used are normal corrosion-proofing pigments employed in undercoat materials.

Specific embodiment examples of corrosion-proofing pigments which may be used are chromate pigments, such as zinc chromate and strontium chromate, and any non- polluting corrosion-proofing pigments which do not contain chromium, but from the viewpoint of environmental conservation, it is preferable to use non-polluting corrosion-proofing pigments.

Examples of non-polluting corrosion-proofing pigments which may be given are: condensed phosphate-based corrosion-proofing pigments and surfaces of condensed phosphate salts treated with metal compounds, such as zinc phosphate-based corrosion-proofing pigments, magnesium phosphate-based corrosion-proofing pigments, aluminum phosphate-based corrosion-proofing pigments, calcium phosphate-based corrosion-proofing pigments, zinc phosphite-based corrosion-proofing pigments, magnesium phosphite-based corrosion-proofing pigments, calcium phosphite-based corrosion-proofing pigments and aluminum phosphite-based corrosion-proofing pigments; zinc-based corrosion-proofing pigments, such as zinc molybdate corrosion-proofing pigments, zinc cyanamide- based corrosion-proofing pigments; calcium zinc cyanamide-based corrosion-proofing pigments; and silica. These may be used individually, or as mixtures of 2 or more thereof .

[0029]

In addition to anticorrosion pigments, there may be compounded into the primer compositions according to the present invention, as required, pigments conventionally used for coatings, such as inorganic pigments, organic pigments and processing pigments. Examples of the organic pigments which may be given are: azo lake-based pigments, phthalocyanine-based pigments, indigo-based pigments, perylene-based pigments, quinophthalone-based pigments, dioxazine-based pigments, quinacridone-based pigments, isoindolinone- based pigments and metal complex pigments. Examples of inorganic pigments which may be given are: yellow iron oxide, Bengala, titanium dioxide and carbon black.

There may also be compounded in, as required, lamellar pigments, such as aluminum pigments, or pearl pigments. These pigments are not especially limited and they may be used individually, or as mixtures of 2 or more thereof.

[0030]

The primer compositions according to the present invention are preferably solutions or dispersions in organic solvents of each of the components, component (A) , component (B) , component (D) and component (E) . Examples of the said organic solvents which may be given are: hexane, heptane, isooctane, unsaturated aliphatic hydrocarbons, benzene, toluene, xylenes (ortho-, meta- and para-) , cyclohexane, dioxan, tetra- hydrofurane, Cellosolve, methylcellosolve, butylcello- solve, methylcarbitol, 2-methoxyethanol, 2-butoxyeth- anol, diethylene glycol, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, diethylene glycol monoethyl ether acetate, triethylene glycol monomethyl ether, l-methoxy-2-propanol, l-ethoxy-2- propanol, dipropylene glycol monomethyl ether, acetone, methyl ethyl ketone, isophorone, cyclohexanone, methyl acetate, ethyl acetate, propyl acetate, isobutyl acetate, pentyl acetate, 3-methoxybutyl acetate, 2- ethylhexyl acetate, benzyl acetate, cyclohexyl acetate, ethylene glycol monoacetate, Cellosolve acetate, carbitol acetate, ethyl acetoacetate, pyridine, N- methyl-2-pyrrolidone, formamide, N,N-dimethylformamide and acetamide.

[0031] The materials used according to the present invention whereon the primer compositions are coated are preferably metal plate, such as iron and copper plate, these metals with plating thereon plated steel sheet, but particularly preferably zinc-plated steel sheet. When the primer compositions are coated, it is preferable to carry out pre-coating treatment on the surface of materials; this pre-coating treatment may be chemical treatment used as a pre-treatment for pre- coated metals, examples thereof which may be given are chromate treatment, phosphate treatment and complex oxide film treatment.

[0032] Coating of the primer compositions according to the present invention may be carried out by various processes; examples of coating processes which may be used are coating by means of: roll coaters, flow coaters, dipping or spraying. Of these, coating by means of roll coaters is preferable, from the viewpoint of obtaining film thickness control and uniformity. Baking of the coated films from application of the primer compositions may normally be carried out under the hardening conditions of 100° to 300⁰C, for 5 seconds to 5 minutes, hardening may be carried out under conditions which are normal for hardening in the field of precoating, for example, with a roll coater with a peak material temperature of 120° to 26O⁰C, for 15 to 120 seconds.

The thicknesses of the dried primer films, obtained by coating the primers according to the present invention, are normally preferably in the range 1 to 10 μm, more preferably 3 to 7 μm.

[0033]

A polyamide (nylon) resin coating is preferable as a coating on the coated primer films according to the present invention, from the viewpoint of adhesion. Examples of the polyamide (nylon) resins which may be given are: polyamide 6, from ring-opening polymerization of ε-caprolactam; polyamide 66, from polycondensation of hexamethylenediamine and adipic acid; polyamide 610, from polycondensation of hexamethylenediamine and sebacic acid; polyamide 11, from polycondensation of 11-aminoundecanoic acid; and polyamide 12, from ring-opening polymerization of ω- laurolactam or polycondensation of 12-aminododecanoic acid, which are the same constituents as the solvent- insoluble nylon resin beads used for the primer compositions according to the present invention. An example of a process for the formation of the polyamide resin coatings which may be given is to form a sheet of molten resin by heating to a temperature above the melting point of a polyamide resin, but processes are not limited to this one and various processes may be cited.

The thicknesses of the polyamide resin coatings are preferably 50 to 200 μm, more preferably 80 to 150 μm.

[Examples] [0034]

The present invention will be described more concretely below by means of Manufacturing Examples, Examples of its execution and Comparative Examples. The present invention will not be limited by these Examples . Hereunder, unless specified, "parts" and "%" respectively signify "parts by mass" and "% by mass" . In addition, in Table 1 to Table 3 , the units for the numerical values giving the quantities compounded of each component are parts by mass.

Appraisals of all the properties in the Examples and Comparative Examples were carried out by the undermen- tioned methods .

[0035] <Methods of Appraisal of Coating Operation Properties and Coated Films>

(Coating Operation Properties of Primer Compositions) Primer compositions were diluted with diluting solvent

[N-methylpyrrolidone: isophorone mixture = 50:50 (ratio by mass) ] to a value of 60 seconds with Ford cup Number 4 (25°C) ; the diluted primer compositions were coated with a bar coater onto the surfaces of zinc- electroplated steel sheets (length, 100 mm; width, 67 mm; thickness, 0.3 mm), such that the dried film thicknesses were 4 to 6 μm. The texture of the coated primer films at this point were appraised according to the criteria below, as an appraisal of coating operation properties of the primer compositions. O : no problems

O : no problems with respect to utilization x: round texture: problems with respect to utilization.

[0036]

Primary Adhesive Performance

Primer compositions were diluted with diluting solvent

[N-methylpyrrolidone: isophorone mixture = 50:50 (ratio by mass) ] to a value of 60 seconds with Ford cup Number 4 (25°C) ; the diluted primer compositions were coated with a bar coater onto the surfaces of zinc- electroplated steel sheets (length, 100 mm; width, 67 mm; thickness, 0.3 mm), such that the dried film thicknesses were 4 to 6 μm, after which the films were immediately baked and hardened at 260⁰C for 40 seconds. At this point, an approximately 40 mm length region was created which was not coated with primer composition. Nylon pellets [Trade Name: Rilsan B BMF 0 (manufactured by Alkema Company) ] were melted at 300⁰C and coated with an applicator so that the thickness was 100 to 110 μm. At this point, continuous films were made by simultaneously coating the primed regions and the regions where no primer composition had been coated, so that test pieces were obtained. Ten-millimeter-wide notches were introduced into the coated films in the longitudinal direction of the test pieces and the coated nylon films were tensioned at a set rate from the regions where no primer composition had been coated; the primer compositions were appraised by the state of peeling of the regions where the primer composition had been coated.

[0037]

(i) Adhesion of Plated Steel Sheet and Coated Primer Films O : Nylon film broke at primer-coated sites.

O : Aggregation failure or surface peeling at primer- coated sites, then coated nylon film breakage. x: There was peeling at the interface between a plated steel sheet and a coated primer film, but no breakage of the coated nylon film. [0038]

(ii) Initial Adhesion between Coated Primer Films and Topcoat Films Test plates were prepared in a similar manner to those for adhesion (primary adhesion) of coated primer films to plated steel sheet, and the initial adhesion (primary adhesion) between a coated primer film and a coated nylon film was appraised using the undermentioned criteria.

Θ : Nylon film broke at primer-coated sites. O : Aggregation failure or surface peeling at primer- coated sites, then coated nylon film breakage, x: There was peeling at the interface between a plated steel sheet and a coated primer film, but no breakage of the coated nylon film.

[0039]

(Bending Properties) Test plates were prepared for testing bending properties by diluting primer compositions with diluting solvent [N-methylpyrrolidone: isophorone mixture = 50:50 (ratio by mass) ] to a value of 60 seconds with Ford cup Number 4 (25°C) ; the diluted primer compositions were coated with a bar coater onto the surfaces of zinc- electroplated steel sheets (length, 100 mm; width, 67 mm; thickness, 0.3 mm), such that the dried film thicknesses were 4 to 6 μm, after which the films were immediately baked and hardened at 260⁰C for 40 seconds. With regard to test pieces cut into 5 cm widths at a room temperature of 2O⁰C, as bending test pieces, 180° adhered bending was carried out, making the coated film the outside of the bend: for OT, with nothing inserted in the bend; for IT, 1 sheet thickness of the same coated plate as the test piece was inserted inside the bend; for 2T, 2 sheet thicknesses of the same coated plate as the test piece were inserted inside; 180° adhered bending was also carried out, making the coated film the outside of the bend, for 4T, with 4 sheet thicknesses of the same coated plate as the test piece inserted inside. The bending test results were appraised according to the following criteria: O : no cracking produced with 4T (4 thicknesses) .

O : there was slight cracking with 4T bending, but no problems with respect to utilization. x: cracks produced: problems with respect to utilization.

[0040]

[Adhesion (Secondary Adhesion) between Coated Primer

Films and Topcoat Films after Gasohol Immersion] Primer compositions were diluted with diluting solvent

[N-methylpyrrolidone : isophorone = 50:50 (ratio by mass)] to a value of 60 seconds with Ford cup Number 4

(25⁰C) ; the diluted primer compositions were coated with a bar coater onto the surfaces of zinc- electroplated steel sheets (length, 100 nun; width, 67 mm; thickness, 0.3 mm), such that the dried film thicknesses were 4 to 6 μm, after which the films were immediately baked and hardened at 260⁰C for 40 seconds. At this point, a region was prepared where an approximately 40 mm length was not coated with primer composition.

[0041]

Nylon pellets [Trade Name: Rilsan B BMF 0 (manufactured by Alkema Company) ] were melted at 300⁰C and coated with an applicator so that the thickness was 100 to 110 μm. At this point, a continuous film was made by simultaneously coating the region where no primer composition had been coated, and a test piece was obtained. The test piece obtained was immersed in gasohol at 20⁰C for 120 hours, after which it was kept at room temperature for 1 hour, 10-mm-wide notches were introduced in the longitudinal direction, the coated nylon film was tensioned from the region where no primer composition had been coated and the state of peeling of the region which had not been coated with primer composition was assessed by means of the undermentioned criteria.

O : coated nylon film broke at the primer-coated site. O : aggregation failure or surface peeling at primer- coated site, then coated nylon film breakage. x: There was peeling at the interface between plated steel sheet and a coated primer film, but no coated nylon film breakage.

[0042]

Primer Composition Manufacturing Example P-I Vylomax HRIlNN (Trade Name for polyamide resin, manufactured by Toyo Boseki K K; number average molecular weight 15,000; solid resin fraction, 15%; 381.8 parts), barium sulfate SS-50 [Trade Name for extender pigment, manufactured by Sakai Kagaku K K (Sakai Chemical Company), 9.5 parts]; matting agent HK125 (Trade Name for anticorrosion pigment, manufactured by Degussa Company; 22.3 parts); N-methylpyrrolidone (50 parts); and isophorone (50 parts) were charged to a disperser and dispersed until the particle size was not more than 30 μm. When the target particle size was reached, dispersion was stopped and there were added: Rilsan Fine Powder D30 Naturell (Trade Name for solvent- insoluble nylon resin beads, manufactured by Alkema Company; mean particle diameter, 25 μm; 140 parts) ; a solution comprising PA-100 (Trade Name for solvent- soluble polyamide resin, manufactured by Fuji Kasei Kogyo K K; solid resin fraction, 100%; 38.2 parts) and jERlO01 (Trade Name for epoxy resin, manufactured by Japan Epoxy Resins Company; epoxy value, 118; solid resin fraction, 100%; 57.3 parts) in a solvent which was a mixture of N-methylpyrrolidone (50 parts) and isophorone (50 parts) ; Shonol CKS-704 (phenol resin, manufactured by Showa Kobunshi K K; number average molecular weight, 430; solid resin fraction, 59%; 21.6 parts) ; Yuban 80S [Trade Name for melamine resin manufactured by Mitsui Kagaku K K (Mitsui Chemical Company) ; weight average molecular weight, 3700; solid resin fraction, 50%; 25.5 parts]; N-methylpyrrolidone (51.9 parts); and isophorone (51.9 parts) the dispersion was taken out and thoroughly stirred, when Manufacturing Example P-I of the primer composition given in Table 1 was obtained. In addition, the numerical values of the heating residues listed in the characteristic values columns for the primers given in Tables 1 to 3_ show the percentage contents (% by mass) of the heating residues versus the total mass of the primer compositions and the classification of the heating residues was the percentage content (% by mass) of the heating residues when the numerical values of the percentage contents (% by mass) of the resins and pigments were totalled.

[0043]

Primer Composition Manufacturing Examples P-2 , P-2 , P5 to P23 P-2 , P- 3 , P5 to P23 in Tables 1 to 3_ were obtained in a similar manner to Primer Manufacturing Example P-I .

[ 0044 ]

Primer Composition Manufacturing Example P-4 Vylomax HR13NX (Trade Name for polyamide resin, manufactured by Toyo Boseki K K; number average molecular weight 10,000; solid resin fraction, 30%; 224 parts), Orgasol 2002ES3DNAT3 (solvent-insoluble nylon resin beads, manufactured by Alkema Company; mean particle diameter, 40 μm; 128 parts) , N-methylpyrrolidone (50 parts); and isophorone (50 parts) were charged to an agitator and thoroughly agitated. There were then added a solution comprising PA-100 (Trade Name for solvent-soluble polyamide resin, manufactured by Fuji Kasei Kogyo K K; solid resin fraction, 100%; 35.2 parts) and JERlOOl (Trade Name of epoxy resin, manufactured by Japan Epoxy Resins Company; epoxy value, 118; solid resin fraction, 100%; 64 parts) in a solvent which was a mixture of N-methylpyrrolidone (50 parts) and isophorone (50 parts) ; Shonol CKS-704 (phenol resin, manufactured by Showa Kobunshi K K; number average molecular weight, 430; solid resin fraction, 59%; 21.7 parts); Yuban 20SB (Trade Name for melamine resin manufactured by Mitsui Kagaku K K; weight average molecular weight, 5780; solid resin fraction, 50%; 25.6 parts); N-methylpyrrolidone (150.8 parts); and isophorone (150.7 parts) and thoroughly agitated, when Manufacturing Example P-4 of the primer composition given in Table 1 was obtained. [0045] Example 1

The coating operation properties of primer compositions were appraised by the method stated in (Coating Operation Properties of Primer Compositions) , using the primer composition of Manufacturing Example P-I; the results are given in Table 4.

Bending properties were next appraised by the method stated for (bending properties) ; the results are given in Table 4. Adhesion was assessed by the method stated for [adhesion (primary adhesion) of plated steel sheet and coated primer films] and [initial adhesion (primary adhesion) of coated primer films and topcoat films] ; the results are given in Table 4. In addition, adhesion was evaluated by the method stated in [adhesion of coated primer films and topcoat films after gasohol immersion (secondary adhesion) ] ; the results are given in Table 4.

[0046]

Examples 2 to 14; Comparative Examples 1 to 9 Each of the appraisals were carried out in a similar manner to those for Example 1; the results are given in Table 4 and Table 5. [0047]

[Table 1]

[0048]

[Table 2]

[ 0049 ] [Table 3 ]

[0050]

The figures inside the brackets in the Tables represent the following:

1) Vylomax HRIlNN: Trade Name for polyamide-imide resin, manufactured by Toyo Boseki K K; number average molecular weight, 10,000; solid resin

10 fraction, 15% by mass.

2) Vylomax HR13NX: Trade Name for polyamide-imide resin, manufactured by Toyo Boseki K K; number average molecular weight, 10,000; solid resin fraction, 30% by mass.

3) HI-405-30: Trade Name for polyamide-imide resin, manufactured by Hitachi Kasei Kogyo K K; number average molecular weight, 19,000; solid resin fraction, 30% by mass.

4) PA-100: Trade Name for solvent-soluble polyamide resin, manufactured by Fuji Kasei Kogyo K K; solid resin fraction, 100%.

5) PA-102A: Trade Name for solvent-soluble polyamide resin, manufactured by Fuji Kasei Kogyo K K; solid resin fraction, 100%.

[0051]

6) PA-200: Trade Name for solvent-soluble polyamide resin, manufactured by Fuji Kasei Kogyo K K; solid resin fraction, 100%.

7) PA-200: Trade Name for solvent-soluble polyamide resin, manufactured by Fuji Kasei Kogyo K K; solid resin fraction, 100%.

8) Rilsan Fine Powder D30 Naturell: Trade Name for solvent-insoluble nylon resin beads, manufactured by Alkema Company; mean particle diameter, 25 μm. 9) Orgasol 2002ES4NAT3: Trade Name for solvent- insoluble nylon resin beads, manufactured by Alkema Company; mean particle diameter, 40 μm. 10) Orgasol 2002ES3NAT3: Trade Name for solvent- insoluble nylon resin beads, manufactured by Alkema Company; mean particle diameter, 30 μm. [0052]

11) JERlOOl: Trade Name for epoxy resin, manufactured by Japan Epoxy Resins Company; epoxy value, 118; solid resin fraction, 100%.

12) JER1002: Trade Name for epoxy resin, manufactured by Japan Epoxy Resins Company; epoxy value, 87; solid resin fraction, 100%. 13) JER834: Trade Name for epoxy resin, manufactured by Japan Epoxy Resins Company; epoxy value, 226; solid resin fraction, 100%.

14) YD-907: Trade Name for epoxy resin, manufactured by Tohto Kasei Company; epoxy value, 38; solid resin fraction, 100% by mass.

15) Shonol CKS-704: Trade Name for phenol resin, manufactured by Showa Kobunshi K K; number average molecular weight, 430; solid resin fraction, 59% by mass.

[0053]

16) Shonol CRG-951: Trade Name for phenol resin, manufactured by Showa Kobunshi K K; number average molecular weight, 750; solid resin fraction, 100% by mass.

17) Yuban 80S: Trade Name for melamine resin manufactured by Mitsui Kagaku K K; weight average molecular weight, 3,700; solid resin fraction, 50% by mass .

18) Yuban 20SB: Trade Name for melamine resin manufactured by Mitsui Kagaku K K; weight average molecular weight, 5,780; solid resin fraction, 50% by mass.

19) Yuban 122: Trade Name for melamine resin manufactured by Mitsui Kagaku K K; weight average molecular weight, 1,560; solid resin fraction, 60% by mass. 20) Barium sulfate SS-50: extender pigment, manufactured by Sakai Kagaku K K.

21) Matting agent HK-125: Trade Name for anticorrosion pigment; manufactured by Degussa Company.

22) TiPure R-706: Trade Name for titanium oxide; manufactured by DuPont Company.

23) Carbon black FW200: Trade Name for carbon black; manufactured by Degussa Company.

24) JER828: Trade Name for epoxy resin, manufactured by Japan Epoxy Resins Company; epoxy value, 297; solid resin fraction, 100% by mass.

[0054]

[Table 4]

[0055] [Table 5]

[0056] The primer compositions according to the present invention, as shown in Examples 1 to 1_4 in Table 3 , may^¬ be obtained in all cases with performances at or above the level where there are no problems with regard to practical use, as long as they are within the Scope of the Patent Claims of the present invention.

However, when the contents of the polyamide-imide resins, solvent-soluble polyamide resins or solvent- insoluble nylon resin beads are outside the Scope of the Patent Claims, as shown by Comparative Examples 1 to 5, adhesion between coated primer films and topcoat films, or adhesion between coated primer films and topcoat films after gasohol immersion, is poor. In addition, when the contents of epoxy resins are outside the Scope of the Patent Claims, as shown by Comparative Examples 6 and 7, adhesion between coated primer films and plated steel sheet, and bending properties, are poor. Further, when hardener contents are outside the Scope of the Patent Claims, as shown by Comparative Examples 8 and 9, adhesion between coated primer films and topcoat films after gasohol immersion, or bending properties, are poor.

[0057]

As above-mentioned, if each of the components of the primer compositions are within the Scope of the Patent Claims of the present invention, the coating operation properties of the primer composition are excellent, and primer compositions which are useful as undercoat coating materials for polyamide resin films may be obtained, which can form coated primer films with excellent: initial adhesion of plated steel sheet and coated primer films (primary adhesion) ; initial adhesion of coated primer films and topcoat films (primary adhesion) ; bending properties; and adhesion of coated primer films and topcoat films after gasohol immersion (secondary adhesion) .

Claims

Claims [Claim 1]

Primer compositions containing (A) polyamide-imide resins, (B) solvent-soluble polyamide resins, (C) solvent-insoluble nylon resin beads, (D) epoxy resins and (E) hardeners, characterized in that there are the contents: 10 to 30% by mass of component (A); 5 to 20% by mass of component (B) ; 59 to 15% by mass of component (C) ; 10 to 30% by mass of component (D) ; and

1 to 20% by mass of component (E) , per total mass of the solid resin components (A) , (B) , (C) , (D) and (E) .

[Claim 2] Primer compositions, as claimed in claim 1, characterized in that component (E) is a phenol resin and/or an amino resin.

[Claim 3] Primer compositions, as claimed in claim 1 or claim 2, characterized in that the primer compositions are primer compositions which are used as undercoats for polyamide resin films.