WO2008152461A1

WO2008152461A1 - Primer composition

Info

Publication number: WO2008152461A1
Application number: PCT/IB2008/001256
Authority: WO
Inventors: Toshiya Kitamura; Hayato Ishibashi
Original assignee: Basf Coatings Japan Ltd.
Priority date: 2007-06-15
Filing date: 2008-05-15
Publication date: 2008-12-18
Also published as: JP2008308623A

Abstract

To provide primer compositions with which it is possible to form primer paint films with which the adhesion on metals such as iron, copper and the like, plated steel ' sheets on which these have been plated, and especially zinc plated steel sheets, is excellent, with which the adhesion with the topcoat film when a polyamide (nylon) resin forms the topcoat film is also excellent and which has excellent gasohol properties in particular. [Means of Resolution] A primer composition which contains (A) poly- amide imide resin, (B) nylon resin beads, (C) epoxy resin and (D) hardening agent wherein the proportions with respect to the total mass of resin solid fractions of the (A), (B), (C) and (D) components included are from 10 to 30 mass% of the (A) component, from 79 to 20 mass% of the (B) component, from 10 to 30 mass% of the (C) component and from 1 to 20 mass% of the (D) component.

Description

Primer compositions

Specification [Technical Field] [0001]

This concerns primer compositions with which it is possible to form primer paint films which have excellent adhesion on metals such as iron and copper, plated steel sheets on which these have been plated, and especially zinc plated steel sheets, with which the adhesion of the topcoat film when a polyamide (nylon) resin is used for the topcoat film is also excellent and of which the resistance to solvents such as gasoline and the like is also excellent. [Technical Background] [0002]

Pipes which are characterized by the fact that the external plastic jacket layer is a layer comprising thermoplastic resin, and especially polyamide resin, which has been extruded over a chromate layer on the outer peripheral surface of an inner metal pipe are known for the pipes of automobile brake systems, fuel systems and hydraulic systems (for example, see Patent Citation 1) . However, there is a problem in that with these pipes the adhesion is inadequate after immersion in gasohol (gasoline mixed with a low concentration of ethanol; a fuel which has been put into practical use after development from the viewpoints of reducing the amount of nitrogen dioxide in the exhaust and the octane value in the United States and Brazil) . [0003] The method for the surface treatment of metal pipes on which there are formed a zinc or zinc/nickel plated metal layer which is formed on the outer peripheral surface of the metal pipe, a chemical forming treatment layer which has a trivalent chromium compound or a phosphoric acid compound as the main component which is formed on said plated metal layer, an epoxy resin intermediate layer comprising epoxy resin paint to which anti-rust pigment which has condensed phosphate and magnesium silicate based compounds as the main components which is formed on said chemical forming treatment layer and a resin layer

(a resin layer comprising poly (vinyl fluoride) resin, poly (vinylidene fluoride) resin or polyamide resin) which is formed on the aforementioned epoxy resin intermediate layer is known as a method for the surface treatment of metal pipes (for example, see Patent Citation 2). However, although hexavalent chromium is not included in the treatment or paint with this method, trivalent chromium is included and there is a problem in that it is not completely chromium-free as is being demanded by the market and there is a further problem in that the adhesion after immersion in gasohol is inadequate. [0004]

Furthermore, the method in which a surface treatment layer which does not contain chromium and/or a primer coat for which a commercial polyamide primer is used are inserted between an alumicoat and a polyamide resin layer of pipes comprising a metal inner pipe, an alumicoat which has been formed on the outer surface of the inner pipe and a polyamide layer which is linked to the alumicoat is known for liquids, and especially fuel and hydraulic fluids, in automobiles (for example, see Patent Citation 3). However, there is a problem in that the gasohol resistance (paint film adhesion test after immersion in gasohol) is inadequate. [0005]

Furthermore, the provision of low temperature hardenability and good adhesion by adding epoxy resin to a polyamide resin is known (for example, see Patent Citation 4) . However, there is a problem in that the paint film is brittle and the flex workability is inadequate . [0006]

Furthermore, a method of coating metal objects is known which is characterized in that a primer composition in which an inorganic anti-rusting agent has been compounded in at least one type of binder selected from among the group comprising binder component (A) which contains epoxy resin and amino resin and/or phenol resin, binder component (B) which contains polyester resin, epoxy resin and phenol resin and binder component (C) which contains α-olefin/α, β- ethylenic unsaturated carboxylic acid copolymer resin is coated on the surface of a metal object which is to be painted, a thermoplastic resin based paint (vinyl fluoride resin based paint, vinylidene fluoride resin based paint or a polyamide resin based paint) is coated via the primer paint film obtained and a thermoplastic resin film is formed (for example see Patent Citation 5) . However, with this method there is a problem in that the gasohol resistance of the composite layer paint film where a polyamide resin based paint has been coated is inadequate. [0007]

[Patent Citation 1] Japanese publication H9-509723 [Patent Citation 2]

Japanese unexamined patent application laid open

2003-194288

[Patent Citation 3]

Japanese unexamined patent application laid open 2003-343767

[Patent Citation 4]

Japanese unexamined patent application laid open H9 -302226

[Patent Citation 5] Publication WO2003-033173 [Disclosure of the Invention] [Problems to be Resolved by the Invention] [0008]

The present invention is intended to provide primer compositions with which it is possible to form primer paint films which have excellent adhesion on metals such as iron and copper, plated steel sheets on which these have been plated, and especially zinc plated steel sheets, with which the adhesion of the top coat film when a polyamide (nylon) resin is used for the topcoat film is excellent and of which the gasohol properties are also excellent.

[Means of Resolving These Problems] [0009]

As a result of thorough research carried out with a view to resolving the abovementioned problems, the inventors have discovered that the abovementioned problems can be resolved by means of a primer composition which contains polyamideimide resin, nylon resin beads, epoxy resin and hardening agent in specified proportions, and the invention is based upon this discovery.

That is to say, the invention provides a primer composition which contains (A) polyamideimide resin, (B) nylon resin beads, (C) epoxy resin and (D) hardening agent wherein the proportions with respect to the total mass of resin solid fractions of the (A) , (B) , (C) and (D) components included are from 10 to 30 mass% of the (A) component, from 79 to 20 mass% of the (B) component, from 10 to 30 mass% of the (C) component and from 1 to 20 mass% of the (D) component.

Furthermore, the invention provides a primer composition claim in which the (D) component in the abovementioned primer composition is a phenol resin and/or amino resin.

Furthermore, the invention provides a primer composition in which the primer composition in the abovementioned primer composition is a primer composition which is used as an undercoat paint for a polyamide resin film. [Effect of the Invention] [0010]

The primer compositions of this invention can form primer paint films which have excellent adhesion on metals such as iron and copper, plated steel sheets on which these have been plated, and especially zinc plated steel sheets, with which the adhesion of the top coat film when a polyamide (nylon) resin is used for the topcoat film is also excellent and which exhibits excellent performance in respect of its gasohol properties . [Embodiment of the Invention] [0011]

The present invention is a primer composition which contains polyamideimide resin, nylon resin beads, epoxy resin and hardening agent.

The resin acid value of the (A) component polyamideimide resin which is used in the invention is preferably not more than 30 mgKOH/g, and most desirably not more than 10 mgKOH/g. If the acid value exceeds 30 mgKOH/g then the storage stability at 50⁰C is reduced and this is undesirable.

Furthermore, the number average molecular weight of the (A) component polyamideimide resin is preferably from 9,000 to 28,000, and most desirably from 12,000 to 25,000. If the number average molecular weight is less than 9,000 the gasohol properties decline, and if it exceeds 28,000 then the painting operability is reduced and this is undesirable.

The role of the (A) component in this invention is to suppress swelling of the paint film on immersion in gasohol and to ensure adhesion of the primer paint film after immersion in gasohol. [0012]

No particular limitation is imposed upon the method used to produce the polyamideimide resin and various methods of production can be used. The polyamideimide resin can be produced by means of a known method of production and, in more practical terms, it can be obtained by reacting (a) a polycarboxylic acid with three or more functional groups which has a acid anhydride group, (b) dicarboxylic acid with two functional groups, (c) an aromatic isocyanate or aromatic diamine and (d) a lactam in a polar organic solvent. In terms of the proportions of (a) to (d) , the compounding proportions of (a) and (b) as the equivalent ratio is preferably from 4/6 to 9/1 and the proportion of (c) as a ratio with the total number of carboxyl groups and amino groups of (a) and (b) is preferably from 8 to 16, and the proportion of (d) with respect to the total mass of

(a), (b) and (c) is preferably from 0.1 to 20 mass%. The reaction is carried out in the presence of a polar organic solvent in the temperature range from 80 to 150⁰C by heating and condensing while removing the carbon dioxide gas which is eliminated and produced when an aromatic diisocyanate is being used from the reaction system. The reaction time can be selected appropriately in accordance with the batch size and the reaction conditions which are being used. [0013]

N-Methyl-2-pyrrolidone, N, N-dimethylformamide, N,N-dimethylacetamide, dimethylsulfoxide, γ-butyro- lactone, diethylene glycol dimethyl ether, triethylene glycol ether and the like, for example, can be used individually, or in combinations of two or more types, for the polar organic solvent, and the amount used is preferably from 1.0 to 5.0 times (by mass) the amount of polyamideimide resin which is being produced. After completing the synthesis of the polyamideimide resin in those cases where an aromatic diisocyanate has been used the terminal isocyanate groups of the resin can also be blocked with a blocking agent such as an alcohol, a lactam, an oxime or the like. [0014]

Examples of commercially available polyamideimide resins include Vylomax HRIlNN, Vylomax 13NX, Vylomax 14ET (all produced by the Toyo Boseki Co.), HI-405-30, HPC-5000, HPC-5010S, HPC5020, HPC-5030, HPC-6000, HPC-6100, HPC-7200 and HPC-9000 (all produced by the Hitachi Kasei Kogyo Co.). [0015]

The fusion temperature of the (B) component nylon resin beads which are used in the invention is preferably at least 150⁰C and most desirably at least

170⁰C. If the fusion temperature is less than 150⁰C then the thermal stability of the resin on baking at a high temperature tends to fall and this is undesirable.

Furthermore, the (B) component nylon resin beads are preferably nylon resin beads which are insoluble in solvents such as alcohols, esters, ketones and the like. Furthermore, the average diameter of the (B) component nylon resin beads is preferably from 5 to 100 μm, and most desirably from 10 to 50 μm. If the average particle diameter is less than 5 μm then the paint viscosity tends to be high and this is undesirable, and in those cases where it exceeds 100 μm the storage stability tends to fall and this is undesirable.

The role of the (B) component nylon resin beads in this invention is to ensure adhesion between the primer pain film and the polyamide resin film which forms the topcoat film. [0016]

Polyamide 6 obtained by the ring-opening polymerization of ε-caprolactam, polyamide 66 obtained by the polycondensation of hexamethylenediamine and adipic acid, polyamide 610 obtained by the polycondensation of hexamethylenediamine and sebacic acid, polyamide 11 obtained by the polycondensation of 11-aminoundecanoic acid, and polyamide 12 obtained by the ring-opening polymerization of ω-laurolactam or the polycondensation of 12-aminodecanoic acid and the like can be cited for the nylon resin beads . [0017] Commercially available nylon resin beads include Rilsan Fine Powder D30 NATURELL, Rilsan Fine Powder D40 NATURELL, Rilsan Fine Powder D50 NATURELL, Orgasol 1002DNAT1, Orgasol 1002ES4NAT1, Orgasol 2002ES4NAT3, Orgasol 2002ES3NAT3, Orgasol 3501EDXNADl, 3502DNADl (all produced by the Alchema Co.), SNP Powder 13, SNP Powder 19 (both produced by the Metalcolor Co.) and A1020LP (produced by the Unichica Co.) . [0018]

The epoxy group value of the (C) component epoxy resin which is used in the invention is preferably from 30 to 250 mgKOH/g, and most desirably from 50 to 130 mgKOH/g. If the epoxy group value exceeds 250 mgKOH/g then the adhesion on plated steel sheets tends to fall, and if it is less than 30 mgKOH/g then the painting operability tends to decline.

The role of the (C) component epoxy resin in this invention is to ensure adhesion between the primer paint film and a plated steel sheet. [0019]

The epoxy resins which have at least two epoxy groups in one molecule are preferred for the epoxy resin which is used in this invention, and the known liquids epoxy and solid epoxy resins known in the past can be used without limitation. Furthermore, in those cases where a solid epoxy resin is used said resin is used as a solution or dispersion in an organic solvent in which it can be dissolved or dispersed. [0020]

Examples of commercially available epoxy resins include the bisphenol/epichlorhydrin type epoxy resins such as JERlOOl, JER1002, JER1003, JER1055, JER1004, JER1007 (all produced by the Japan Epoxy Resin Co.), Epototo YD-134 EpotOto YD-OIl, Epototo YS-012, Epototo YD-013, Epototo YD-014, Epototo YD-017, Epototo YD-7011R, Epototo YD-907 (all produced by the Toto Kasei Co.) and D. E. R662E, D. E. R663UE, D. E. R664U, D. E. R667E (all produced by the Dow Chemical Co.). [0021] Phenol resins and amino resins are preferred for the (D) component hardener which is used in this invention, and these may be used individually or conjointly.

The number average molecular weight of a phenol resin is preferably from 300 to 1,500, and most desirably from 400 to 1,000. If the number average molecular weight is less than 300 then the flexibility of the hardened paint film tends to decline, and in those cases where it exceeds 1,500 the storage stability of the paint at 50⁰C tends to fall and this is undesirable. [0022]

Phenol resins can be obtained by reacting phenols with a formaldehyde. Examples of the phenols which can be used for obtaining a phenol resin include the phenols which have one benzene ring per molecule such as phenol, p-ethylphenol, p-n-propylphenol , p-iso- propylphenol , p-n-butylphenol, p-tert-butylphenol, p-tert-ainylphenol , o-cresol, m-cresol, p-cresol, p-cyclohexylphenol , p-octylphenol, p-nonylphenol , 3,5- xylenol, resorcinol, catechol and the like; phenols which have two benzene rings per molecule such as phenyl-o-cresol and p-phenylphenol ; and bisphenol A, bisphenol F and the like, and these can be used individually or in the form of mixtures of two or more types. Furthermore examples of formaldehyde include formaldehyde, paraformaldehyde, trioxane and the like. [0023]

Inorganic acids, organic acids and organic acid metal salts, for example, can be used as catalysts in the reaction of the abovementioned phenols and formaldehydes.

The phenols may be resol-type phenol resins or novolac type phenol resins. From among these the resol type phenol resins are ideal. Furthermore, they may be phenol resins which have been appropriately modified with natural resins, acrylic resins, polyester resins or the like as required. The abovementioned phenol resins may be used individually or two or more types can be selected and used. [0024] Furthermore, the weight average molecular weight of the phenolic resin is preferably from 600 to 20,000, and most desirably from 1,000 to 10,000. If the weight average molecular weight is less than 800 then the flexibility of the hardened paint film tends to fall, and in those cases where it exceeds 20,000 the gasohol properties tend to decline and this is undesirable. Methylolated amino resins which have been obtained by means of the reaction of an aldehyde with an amino component such as melamine resins, urea resins, benzoguanidine resins, acetoguanidine resins, stero- guanidine resins, spiroguanidine resins, dicyandiamide and the like can be cited as examples of the amino resins, and the amino resins may have been modified with epoxy resins, acrylic resins, polyester resins and the like. From the viewpoint of the flexible workability the melamine resins are preferred. The abovementioned amino resins may be used individually, or two or more types may be selected and used. [0025]

The proportions of the (A) component polyamideimide resin, the (B) component nylon resin beads, the (C) component epoxy resin and the (D) component hardening agent included in the primer composition are with respect to the total mass of the resin solid fractions of the (A) , (B) , (C) and (D) components, from 10 to 30 mass% of the (A) component, from 79 to 20 mass% of the (B) component, from 10 to 30 mass% of the (C) component and from 1 to 20 mass% of the (D) component. More desirably, there is from 15 to 22 mass% of the (A) component, from 65 to 40 mass% of the (B) component, from 15 to 25 mass% of the (C) component and from 3 to 15 mass% of the (D) component. The total of the fractional contents of the (A) , (B) , (C) and (D) components is 100 mass%. Moreover, the resin solid fraction signifies the residue on heating measured using the method described in JIS K5601-1-2. [0026] In those cases where the (A) component content is less than 10 mass% the adhesion of topcoat film with the primer paint film after gasohol immersion (the secondary adhesion) falls, and if it exceeds 30 mass% then the initial adhesion of topcoat film with the primer paint film (the primary adhesion) falls and this is undesirable.

In those cases where the (B) component content is less than 20 mass% the primary adhesion of the primer paint film and the topcoat film falls and if it exceeds 79 mass% then the secondary adhesion of the primer paint film and the topcoat film after gasohol immersion falls and this is undesirable.

In those cases where the (C) component content is less than 10 mass% the adhesion between the primer paint film and the plated steel sheet is reduced, and if it exceeds 30 mass% then the flexible workability is reduced and this is undesirable. In those cases where the (D) component content is less than 1 mass% the adhesion between the primer paint film and the topcoat film after gasohol immersion falls and if it exceeds 20 mass% then the flexible workability is reduced and this is undesirable. [0027]

Anti-rust pigments can be compounded in a primer composition of this invention with a view to improving corrosion resistance. The anti-rust pigments which are generally used in undercoat paints can be used for the anti-rust pigment.

The chromium based pigments such as zinc chromate, strontium chromate and the like and the non-polluting type of anti-rust pigment which do not contain chromium, for example, can all be used as actual anti- rust pigments, but the use of the non-polluting type anti-rust pigments is preferred from the viewpoint of environmental protection. [0028] Examples of the non-polluting type anti-rust agents include condensed phosphate based anti-rust agents such as the zinc phosphate based anti-rust pigments, magnesium phosphate based anti-rust pigments, aluminum phosphate based anti-rust pigments, calcium phosphate based anti-rust pigments, zinc phosphite based anti-rust pigments, magnesium phosphite based anti-rust pigments, calcium phosphite based anti-rust pigments, aluminum phosphite based anti-rust pigments and the like and pigments were the surface of condensed phosphates have been treated with a metal compound; zinc based anti-rust pigments such as the zinc molybdate based anti-rust pigments, zinc cyanamide based anti-rust pigments, zinc/calcium cyanamide based anti-rust pigments and the like,- and silica and the like. These can be used individually, or a mixture of two or more types can be used. [0029]

The pigments which have been used in paints in the past, such as inorganic pigments, organic pigments and processed pigments for example, can be compounded as required in addition to the anti-rust pigments in a primer composition of this invention. Examples of the organic pigments include azo-lake based pigments, phthalocyanine based pigments, indigo based pigments, perilene based pigments, quinophthalone based pigments, dioxazine based pigments, quinacridone based pigments, isoindolinone based pigments, metal complex pigments and the like. Furthermore, examples of the inorganic pigments include yellow iron oxide, red iron oxide, titanium dioxide, carbon black and the like.

Furthermore, if required, glitter-pigments such as aluminum pigments and pearl pigments for example can also be compounded. No particular limitation is imposed upon these pigments and they can be used individually or a mixture of two or more types can be used.

[0030]

The primer compositions of this invention are preferably used in a form where each of the (A) , (C) and (D) components have been dissolved or dispersed in an organic solvent. Examples of said organic solvents include hexane, heptane, iso-octane, unsaturated aliphatic hydrocarbons, benzene, toluene, xylene, (o-, m- and p-) cyclohexane, dioxane, tetrahydrofuran, cellosolve, methylcellosolve, butylcellosolve, nethylcarbitol , 2-methoxyethanol , 2-butoxyethanol , diethylene glycol, diethylene glycol mono-ethyl ether, diethylene glycol mono-butyl ether, diethylene glycol mono-ethyl ether acetate, triethylene glycol mono- methyl ether, l-methoxy-2-propanol, l-ethoxy-2- propanol, dipropylene glycol mono-methyl ether, acetone methyl ethyl ketone, isophorone, cyclohexanone, methyl acetate, ethyl acetate, propyl acetate, butyl acetate, isobutyl acetate, pentyl acetate 3-methoxybutyl acetate, 2-ethylhexyl acetate, benzyl acetate, cyclohexyl acetate, ethylene glycol mono-acetate, cellosolve acetate, carbitol acetate, ethyl acetoacetate, pyridine, N-methyl-2-pyrrolidone, formamide, N,N-dimethylformamide, acetamide and the like. [ 0031 ]

Sheets of metal such as iron and copper, or plated steel sheets on which these have been plated, are preferably used as the base material which is painted with a primer composition of this invention, and zinc plated steel sheets are especially desirable. When applying the primer composition the surface of the base material is preferably subjected to a painting pre- treatment, and any of the chemical forming treatments which have been used as pre-treatments for pre-coated metal purposes can be used for this painting pre- treatment, and examples include chromate forming treatments, phosphate forming treatments, composite oxide film treatments and the like. [0032]

Various methods of painting can be used with the primer compositions of this invention and, for example, painting methods with a roll coater, flow coater, dipping coater or sprayer, for example, can be used. The paint film where the primer film has been coated on should generally be baked under hardening conditions of from 100 to 300⁰C for from 5 seconds to 5 minutes, and in the pre-coat painting field with painting with a roll coater for example the hardening should be carried out under hardening conditions of from 15 to 120 seconds where the maximum temperature reached by the base material is from 120 to 260⁰C. Generally, the dry film thickness of the primer paint film obtained by applying a primer composition of this invention is preferably within the range from 1 to 10 μm, and most desirably within the range from 3 to 7 μm. [0033]

From the viewpoint of adhesion a polyamide (nylon) resin film is preferred for the film which is applied over primer paint film of this invention. Examples of the polyamide (nylon) resin include polyamide 6 obtained by the ring-opening polymerization of ε- caprolactam, polyamide 66 obtained by the polycondensation of hexamethylenediamine and adipic acid, polyamide 610 obtained by the polycondensation of hexamethylenediamine and sebacic acid, polyamide 11 obtained by the polycondensation of 11-aminoundecanoic acid and polyamide 12 obtained by the ring-opening polymerization of ω-laurolactam or the polycondensation of 12-aminodecanoic acid which are of the same composition as cited for the nylon resin beads which are used in a primer composition of this invention. The method where polyamide resin which has been heated to a temperature above its fusion point and formed into a sheet and a film is formed, for example, can be cited as a method of forming the film of polyamide resin, but the method is not limited to this method and various methods can be cited. The film thickness of the film of polyamide resin is preferably from 50 to 200 μm, and most desirably from 80 to 150 μm. [Illustrative Examples] [0034]

The invention is described in more practical terms below by means of examples of production, examples and comparative examples. Moreover, the invention is not limited by these examples. In the absence of any indication to the contrary, the terms "parts" and "%" signify "parts by mass" and "mass%". Furthermore, in Tables 1 to 3 the units of the numerical values which indicate the amount of each component compounded are parts by mass. Moreover, in the examples and comparative examples the evaluation of each item was carried out using the method described below. [0035] <Painting Operability and Method of Evaluating the Paint Film>

(Painting Operability of a Primer Composition)

The primer composition was diluted with a diluting solvent (an N-methylpyrrolidone/isophorone = 50/50 (mass ratio) mixed solvent) to Ford cup No.4 (25°C) 60 seconds and the diluted primer composition was painted with a bar coater on the surface of a zinc electroplated steel sheet (length 100 mm, width 67 mm, thickness 0.3 mm) in such a way that the dry paint film thickness was from 4 to 6 μm. The skin of the primer paint film at this time was evaluated in accordance with the criteria indicated below as an evaluation of the painting operability of the primer composition. ® : No problem

O: No problem in practical terms

X: The skin became rounded, a problem in practical terms . [0036]

Primary Adhesion Performance

The primer composition was diluted with a diluting solvent (an N-methylpyrrolidone/isophorone = 50/50 (mass ratio) mixed solvent) to Ford cup No.4 (25°C) 60 seconds and the diluted primer composition was painted with a bar coater on the surface of a zinc electroplated steel sheet (length 100 mm, width 67 mm, thickness 0.3 mm) in such a way that the dry paint film thickness was from 4 to 6 μm and then it was immediately baked and hardened for 40 seconds at 260⁰C. A part on which the primer composition had not been painted of length about 40 mm was produced at this time.

Next nylon pellets (trade name Rilsan B BMF 0 (produced by the Alchema Co.) were fused at 300⁰C and coated with an applicator in such a way as to become from 100 to 110 μm. At this time the part on which the primer composition had not been painted was coated at the same time to form a continuous film and a test sheet was obtained. A cut was made into the paint film with a width of 10 mm in the length direction of the test plate obtained and the nylon paint film was pulled at a constant rate from the part where the primer composition had not been painted and the state of peeling of the part where the primer composition had been painted was evaluated on the basis of the criteria indicated below. [0037]

(i) Adhesion Between the Plated Steel Sheet and the Primer Paint Film ®: The nylon paint film failed at the primer paint film part

O: The nylon paint film failed after cohesive failure or interfacial peeling in the primer paint film part X: There was interfacial peeling between the plated steel sheet and the primer paint film and the nylon paint film did not fail [0038]

(ii) Initial Adhesion Between the Primer Paint Film and the Top Coat Paint Film

A test plate was prepared in the same way as for the adhesion (primary adhesion) between the plated steel sheet and the primer paint film and the initial adhesion (primary adhesion) between the primer paint film and the nylon paint film was evaluated on the basis of the criteria indicated below.

®: The nylon paint film failed at the primer paint film part O: The nylon paint film failed after cohesive failure or interfacial peeling in the primer paint film part X: There was interfacial peeling between the plated steel sheet and the primer paint film and the nylon paint film did not fail [0039]

(Flexibility)

The primer composition was diluted with a diluting solvent (an N-methylpyrrolidone/isophorone = 50/50 (mass ratio) mixed solvent) to Ford cup No .4 (25°C) 60 seconds and the diluted primer composition was painted with a bar coater on the surface of a zinc electroplated steel sheet (length 100 mm, width 67 mm, thickness 0.3 mm) in such a way that the dry paint film thickness was from 4 to 6 μm and then it was immediately baked and hardened for 40 seconds at 26O⁰C to form a flexibility test sheet.

For the flexibility test the test piece was cut to a width of 5 cm and, at a room temperature of 20⁰C, flexed through 180° with nothing on the inside as OT, with one sheet the same as the test piece on the inside as IT or with two sheets the same as the test piece on the inside as 2T with the paint film on the outside, and flexing was carried out through 180° with four sheets the same as the test piece on the inside as 4T with the paint film on the outside. The flexibility was evaluated with the results of the flexing tests on the basis of the criteria indicated below. ® : No cracks produced at 4T

O: Slight cracking on flexing at 4T but not a problem in practice. X: Cracks produced and a problem in practice [0040]

(Adhesion Between the Primer Paint Film and the Topcoat Paint Film After Gasohol Immersion (Secondary- Adhesion) )

The primer composition was diluted with a diluting solvent (an N-methylpyrrolidone/isophorone = 50/50

(mass ratio) mixed solvent) to Ford cup No.4 (25⁰C)

60 seconds and the diluted primer composition was painted with a bar coater on the surface of a zinc electroplated steel sheet (length 100 mm, width 67 mm, thickness 0.3 mm) in such a way that the dry paint film thickness was from 4 to 6 μm and then it was immediately baked and hardened for 40 seconds at 260⁰C. A part on which the primer composition had not been painted of length about 40 mm was produced at this time. [0041]

Next nylon pellets (trade name Rilsan B BMF 0 (produced by the Alchema Co.) were fused at 300⁰C and coated with an applicator in such a way as to become from 100 to 110 μm. At this time the part on which the primer composition had not been painted was coated at the same time to form a continuous film and a test sheet was obtained. The test sheet was immersed in gasohol at 2O⁰C for 120 hours and then left to stand at room temperature for 1 hour and then a cut was made into the paint film with a width of 10 mm in the length direction of the test plate obtained and the nylon paint film was pulled at a constant rate from the parts where the primer composition had not been painted and the state of peeling of the part where the primer composition had been painted was evaluated on the basis of the criteria indicated below.

®: The nylon paint film failed at the primer paint film part

O: The nylon paint film failed after cohesive failure or interfacial peeling in the primer paint film part X: There was interfacial peeling between the plated steel sheet and the primer paint film and the nylon paint film did not fail [0042] Example of Primer Composition Production P-I Vylomax HRlINN (polyamideimide resin, trade name, produced by the Toyo Boseki Co., number average molecular weight 15,000, resin solid fraction 15%) (424 parts), 9.5 parts of Barium Sulfate SS-50 (true pigment, trade name, produced by the Sakai Kagaku Co.), 22.5 parts of matting agent HK125 (anti-rust pigment, trade name, produced by the Degussa Co.), 50 parts of N-methylpyrrolidone and 50 parts of isophorone were introduced into a disperser and dispersed until the particle size was less than 30 μm. On reaching the intended particle size the dispersion was stopped and 159 parts of Rilsan Fine Powder D30 NATURELL (nylon resin beads, trade name, produced by the Alchema Co., average particle size 25 μm) , a solution of solvent for which 50 parts of N-methylpyrrolidone and 50 parts of isophorone were mixed together and in which 64 parts of jERl001 (epoxy resin, trade name, produced by the Japan Epoxy Resin Co., epoxy value 118, resin solid fraction 100 mass%) had been dissolved, 27 parts of Shonox CKS-704 (phenol resin, produced by the Showa Kobunshi Co., number average molecular weight 430, resin solid fraction 59 mass%) 32 parts of Yuban 80S (melamine resin, trade name, produced by the Mitsui Kagaku Co., weight average molecular weight 3,700, resin solid fraction 50 mass%) , 31 parts of N-methylpyrrolidone and 31 parts of isophorone were added and the mixture was taken out and stirred thoroughly and Example of Primer Composition Production P-I shown in Table 1 was obtained. [ 0043 ]

Examples of Primer Composition Production P-2, P-3 and

P-5 to P22

P-2, P-3 and P-5 to P-22 shown in Tables 1 to 3 were obtained on the same way as the example of primer composition production P-I. [0044] Example of Primer Composition Production P-4

Vylomax HR13NX (polyamideimide resin, trade name, produced by the Toyo Boseki Co., number average molecular weight 10,000, resin solid fraction 30%)

(213 parts), 141 parts of Orgasol 2002ES3NAT3 (nylon resin beads, produced by the Alchema Co., average particle size 40 μm) , a solution of solvent for which 50 parts of N-methylpyrrolidone and 50 parts of isophorone were mixed together and in which 77 parts of jERl001 (epoxy resin, trade name, produced by the Japan Epoxy Resin Co., epoxy value 118, resin solid fraction 100 mass%) had been dissolved, 33 parts of Shonox CKS 704 (phenol resin, produced by the Showa Kobunshi Co., number average molecular weight 430, resin solid fraction 59 mass%) , 38 parts of Yuban 20SB (melamine resin, produced by the Mitsui Kagaku Co., weight average molecular weight 5,780, resin solid fraction 50 mass%) , 199 parts of N-methylpyrrolidone and 199 parts of isophorone were added and the mixture was stirred thoroughly and the Example of Primer Composition Production P-4 shown in Table 1 was obtained. [0045] Example 1 Using the Example of Primer Composition Production P-I, the operability of the primer composition was evaluated with the method described under Painting Operability of a Primer Composition and the result is shown in Table 4. Then the flexibility was evaluated with the method described under Flexibility and the result is shown in Table 4. Then the adhesion was evaluated with the methods described in Adhesion (Primary Adhesion) Between the Plated Steel Sheet and the Primer Paint Film and Initial Adhesion (Primary Adhesion) Between the Primer Paint Film and a Topcoat Film and the results are shown in Table 4. Moreover, adhesion was evaluated with the method described in Adhesion Between the Primer Paint Film and the Topcoat Film After Gasohol Immersion (Secondary Adhesion) and the result is shown in Table 4. [0046] Examples 2 to 14 and Comparative Examples 1 to 8

The items were evaluated in the same way as in Example 1 and the results are shown in Table 4 and Table 5. [ 0047 ] Table 1

Example of Primer Composition Production

P-I P-2 P-3 P-4 P-5 P-6 P-7

Vylomax HRlINN 1) 42.4

A Vylomax HRl3NX 2) 18.5 21. 3 13.7 26.4 20.3

HI-405-30 3) 21.3

Rilsan Fine Powder D30 NATURELL 4) 15.9

B Orgasol2002ES4NAT3 5) 16.9

Orgasol2002ES3NAT3 6) 13.7 14. 1 19.0 14.3 18.0 jER 1001 7) 6.4 7.0 7. 7 4.9 5.2 3.3

JER 1002 8) 4.7

C jER 834 9)

YD-907 10)

N-Methylpyrrolidone 5.0 5.0 5.0 5. 0 5.0 5.0 5.0

Isophorone 5.0 5.0 5.0 5. 0 5.0 5.0 5.0

Dl Shonol CKS-704 11) 2.7 3. 3 2.1 2.6 2.6

Shonol CRG-951 12) 2.0

Yuban 80S 13) 3.2

D2 Yuban 20SB 14) 3. 8 2.4 3.0 3.0 o

Yuban 122 15) 5.6

Barium Sulfate SS-50 16) 0.95 0.90 0.90 0.90 0.90 0.90

Pigment Matting Agent HK125 17) 2.25 2.05 2.15 2.15 2.15 2.15

Typure R-706 18) 2.90 1.55 1.55 1.55 1.55

Carbon Black FW200 19) 0.05

Solvent N-Pyrrolidone 8.1 21.0 18.9 19. .9 21.7 17.0 19.1

Isophorone 8.1 21.0 18.9 19. .9 21.6 16.9 19.1

TOTAL 100.0 100.0 100.0 100 .0 100.0 100.0 100.0

Resin Solid Fraction Proportions (A) 20.0 19.0 21.0 20, .0 13.5 26.0 20.0

(B) 50.0 58.0 45.0 44, .0 62.5 47.0 59.0

(C) 20.0 16.0 23.0 24, .0 16.0 17.0 11.0

(D) 10.0 7.0 11.0 12, .0 8.0 10.0 10.0

Total of Resin Solid Fraction Proportions (A)+(B)+(C)+(D) 100.0 100.0 100.0 100 .0 100.0 100.0 100.0

[ 0048 ] Table 2

Example of Primer Composition Production

P-8 P-9 P-10 P-Il P-12 P-13 P-14

Vylomax HRIlNN 1)

A Vylomax HR13NX 2) 16.2 20.3 16.2 28.4 12.2 11.2 28.4

HI-405-30 3)

Rilsan Fine Powder D30 NATURELL 4)

B Orgasol2002ES4NAT3 5)

Orgasol2002ES3NAT3 6) 13.1 17.7 14.0 10.3 20.4 23.0 7.6 jER 1001 7) 8.8 6.1 6.1 7.9 5.8

JER 1002 8)

C jER 834 9) 3.7

YD-907 10) 8.8

N-Methylpyrrolidone 5.0 5.0 5.0 5.0 5.0 5.0 5.0

Isophorone 5.0 5.0 5.0 5.0 5.0 5.0 5.0

Dl Shonol CKS-704 11) 3.1 1.0 4.6 3.1 0.8 4.6

Shonol CRG-951 12)

Yuban 80S 13) W

D2 Yuban 20SB 14) 3.7 5.5 3.7 1.2 5.5

Yuban 122 15)

Barium Sulfate SS-50 16) 0.90 0.90 0.90 0.90 0.90 0.90 0.90

Pigment Matting Agent HK125 17) 2.15 2.15 2.15 2.15 2.15 2.15 2.15

Typure R-706 18) 1.55 1.55 1.55 1.55 1.55 1.55 1.55

Carbon Black FW200 19)

Solvent N-Pyrrolidone 20.3 20.2 19.5 16.0 22.9 23.4 15.3

Isophorone 20.2 20.1 19.5 16.0 22.9 23.3 15.2

TOTAL 100.0 100.0 100.0 100.0 100.0 100.0 99.9

Resin Solid Fraction Proportions (A) 16.0 20.0 16.0 28.0 12.0 11.0 28.0

(B) 43.0 58.0 46.0 34.0 67.0 75.5 25.0

(C) 29.0 20.0 20.0 26.0 19.0 12.0 29.0

(D) 12.0 2.0 18.0 12.0 2.0 1.5 18.0

Total of Resin Solid Fraction Proportions (A) +(B)+(C)+(D) 100.0 100.0 100.0 100.0 100.0 100.0 100.0

[0049] Table 3

Example of Primer Composition Production

P-15 P-16 P-17 P-18 P-19 P-20 P-21 P-22

Vylomax HRlINN 1) 12.2

A Vylomax HR13NX 2)

HI-405-30 3) 36.5 48.7 3.0 21.3 21.3 17.8 21.3

Rilsan Fine Powder D30 NATURELL 4) 19.5

B Orgasol2002ES4NAT3 5) 10.3 5.2 24.7 21.5 9.7 18.9 11.0

Orgasol2002ES3NAT3 6)

JER 1001 7) 6.1 6.1 7.0 4.3 10.7 6.1 6.1

JER 1002 8)

C JER 828 20) 2.1

N-Methylpyrrolidone 5.0 5.0 5.0 5.0 5.0 5.0 5.0 5.0

Isophorone 5.0 5.0 5.0 5.0 5.0 5.0 5.0 5.0

Dl Shonol CKS-704 11) 2.6 2.6 3.1 1.0 3.1 0.3 5.9

Shonol CRG-951 12)

Yuban 80S 13)

D2 Yuban 20SB 14) 3.0 3.0 3.7 0.9 3.7 7.0

Yuban 122 15) κ>

Barium Sulfate SS-50 16) 0.90 0.90 0.90 0.90 0.90 0.90 0.90 0.90

Pigment Matting Agent HK125 17) 2.15 2.15 2.15 2.15 2.15 2.15 2.15 2.15

Typure R-706 18) 1.55 1.55 1.55 1.55 1.55 1.55 1.55 1.55

Carbon Black FW200 19)

Solvent N-Pyrrolidone 21.0 13.5 8.9 26.6 19.4 18.5 21.5 17.1

Isophorone 21.0 13.4 8.8 26.5 19.3 18.4 21.5 17.0

TOTAL 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0

Resin Solid Fraction Proportions (A) 6.0 36.0 48.0 3.0 21.0 21.0 17.5 21.0

(B) 64.0 34.0 17.0 81.0 70.5 32.0 62.0 36.0

(C) 20.0 20.0 23.0 14.0 7.0 35.0 20.0 20.0

(D) 10.0 10.0 12.0 2.0 1.5 12.0 0.5 23.0

Total of Resin Solid Fraction Proportions (A) + (B) + (D) 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0

[ 0050 ]

The numbers followed by a bracket in the tables are indicated below.

1) Vylomax HRIlNN: Polyamideimide resin, trade name, produced by the Toyo Boseki Co., number average molecular weight 10,000, resin solid fraction 15 mass%, solvent: N-methyl-2-pyrrolidone

2) Vylomax HR13NX: Polyamideimide resin, trade name, produced by the Toyo Boseki Co., number average molecular weight 10,000, resin solid fraction 30 mass%, solvent: mixture of N-methyl-2- pyrrolidone and xylene

3) HI-405-30: Polyamideimide resin, trade name, produced by the Hitachi Kasei Co., number average molecular weight 19,000, resin solid fraction 30 mass%, solvent: mixture of N-methyl-2- pyrrolidone and xylene

4) Rilsan Fine Powder D30 NATURELL: Solvent insoluble nylon resin beads, trade name, produced by the Alchema Co., average particle size 25 μm

5) Orgasol 2002ES4NAT3: Solvent insoluble nylon resin beads, trade name, produced by the Alchema Co., average particle size 40 μm.

[0051] 6) Orgasol 2002ES3NAT3: Solvent insoluble nylon resin beads, trade name, produced by the Alchema Co., average particle size 30 μm. 7) jER 1001: Epoxy resin, trade name, produced by f~~ Japan Epoxy Resin Co., epoxy value 118 mgKOH/g, resin solid fraction 100 mass%

8) jER 1002: Epoxy resin, trade name, produced by the Japan Epoxy Resin Co., epoxy value 87 mgKOH/g, resin solid fraction 100 mass%

9) jER 834: Epoxy resin, trade name, produced by the Japan Epoxy Resin Co., epoxy value 226 mgKOH/g, resin solid fraction 100 mass%

10) YD-907: Epoxy resin, trade name, Produced by the Toto Kasei Co.. epoxy value 38 mgKOH/g, resin solid fraction 100% [0052]

11) Shonol CKS-704: Phenol resin, produced by the Showa Kagaku Co., number average molecular weight 430, resin solid fraction 59%

12) Shonol CRG-951: Phenol resin, produced by the Showa Kagaku Co., number average molecular weight 750, resin solid fraction 100%

13) Yuban 80S: Melamine resin, trade name, produced by the Mitsui Kagaku Co., weight average molecular weight 3,700, resin solid fraction 50 mass%

14) Yuban 20SB: Melamine resin, trade name, produced by the Mitsui Kagaku Co., weight average molecular weight 5,780, resin solid fraction 50 mass% 15) Yuban 122: Melamine resin, trade name, produced by the Mitsui Kagaku Co., weight average molecular weight 1,560, resin solid fraction 60 mass% [ 0053 ]

16) Barium Sulfate SS-50: True pigment, trade name, produced by the Sakai Kagaku Co.

17) Matting Agent HK-125: Anti-rust pigment, trade name, produced by the Degussa Co.

18) Typure R-706: Titanium oxide, trade name, Produced by the DuPont Co.

19) Carbon Black FW200: Carbon black, trade name, produced by the Degussa Co. 20) jER 828: Epoxy resin, trade name, produced by the Japan Epoxy Resin Co., epoxy value 297, resin solid fraction 100 mass%

[0054]

Table 4

Example

1 2 3 4 5 6 7 8 9 10 11 12 13

Primer Composition Number P-I P-2 P-3 P-4 P-5 P-6 P-7 P-8 P-9 P-IO P-Il P-12 P-13 Painting operability of the ® ® @ ® ® ® ® ® @ ® ® ® ® Primer Composition

Adhesion Between the Plated @ ® ® ® ® ® O ® @ ® ® ® O ® Steel Sheet and the Primer σ

\

Paint Film (Primary adhesion)

Initial Adhesion Between the ® ® ® ® ® O ® ® @ ® O ® ® O Primer Paint Film and the Topcoat Film (Primary Adhesion)

Flexibility @ ® ® ® @ ® ® O ® O O O O O

Adhesion Between the Primer ® ® ® ® O ® @ ® O ® O O O ® Composition and the Topcoat Film After Gasohol Immersion (Secondary Adhesion)

[0055]

Table 5

Comparative Example

1 2 3 4 5 6 7 8

Primer Composition Number P-15 P-16 P-17 P-18 P-19 P-20 P-21 P-22

Painting operability of the Primer ® ® ® ® ® ® ® ® Composition

Adhesion Between the Plated Steel Sheet ® @ ® O x ® @ ® _w and the Primer Paint Film (Primary adhesion)

Initial Adhesion Between the Primer ® X X ® @ O ® O Paint Film and the Topcoat Film (Primary Adhesion)

Flexibility ® @ ® @ ® x ® χ

Adhesion Between the Primer Composition X ® @ X θ ® X ® and the Topcoat Film After Gasohol Immersion (Secondary Adhesion)

[ 0056 ]

Provided that the primer compositions of this invention are within the scope of the patent claims, as shown by Examples 1 to 14 in Table 4, it is possible to obtain performance which is above the level where there is no problem in practice in all cases.

However, in those cases where the proportion of polyamideimide resin and/or the nylon resin beads included is outside the scope of the patent claims, as shown in Comparative Examples 1 to 4, the initial adhesion between the primer paint film and the topcoat film or the adhesion between the primer paint film and the topcoat film after gasohol immersion is poor. Furthermore, in those cases where the proportion of epoxy resin included is outside the scope of the patent claims, as shown in Comparative Examples 5 and 6, the adhesion between the primer paint film and the plated steel sheet is poor and the flexibility is poor. Moreover, in those cases where proportion of the hardening agent component included is outside the scope of the patent claim, as shown in Comparative Examples 7 and 8, the adhesion of the primer paint film and the topcoat film after gasohol immersion or the flexibility is poor. [0057]

As indicated above, provided that each component of the primer composition is within the scope of the patent claims of the present invention it is possible to obtain a primer composition which is useful as an undercoat paint for polyamide resin films with which the painting operability of the primer composition is excellent and with which it is possible to form a primer paint film of which the adhesion (primary adhesion) between the plated steel sheet and the primer paint film, the initial adhesion (primary adhesion) between the primer paint film and the topcoat film, the flexibility, and the adhesion (secondary adhesion) between the primer paint film and the topcoat film after gasohol immersion are excellent.

Claims

[Claim 1]

A primer composition which contains (A) poly- amideimide resin, (B) nylon resin beads, (C) epoxy resin and (D) hardening agent wherein the proportions with respect to the total mass of resin solid fractions of the (A) , (B) , (C) and (D) components included are from 10 to 30 mass% of the (A) component, from 79 to 20 mass% of the (B) component, from 10 to 30 mass% of the (C) component and from 1 to 20 mass% of the

(D) component.

[Claim 2]

The primer composition claimed in claim 1 wherein the (D) component is a phenol resins and/or amino resin. [Claim 3]

The primer composition claimed in claim 1 or claim 2 in which the primer composition is a primer composition which is used as an undercoat paint for a polyamide resin film.