JP2009001623A - Primer composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a primer composition which is excellent in the adhesiveness to a metal such as iron or copper and to a plated steel plate prepared by plating a metal, especially a galvanized steel plate, which is excellent in the adhesiveness with a top coating film, when polyamide (nylon) resins are used for the top coating film, and which can especially form a primer coating films excellent in a gasohol properties. <P>SOLUTION: The primer composition comprises (A) a polyamide-imide resin, (B) a solvent-soluble polyamide resin, (C) solvent-insoluble nylon resin beads, (D) an epoxy resin, and (E) a curing agent, in amounts of 10 to 30 mass%, 5 to 20 mass%, 59 to 15 mass%, 10 to 30 mass% and 1 to 20 mass%, respectively, based on the total resin content mass of the components (A), (B), (C), (D) and (E). <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

Excellent adhesion to metals such as iron and copper, or plated steel sheets plated on these, especially galvanized steel sheets, and excellent adhesion to top coats when polyamide (nylon) resin is used as a top coat. It is related with the primer composition which can form the primer coating film excellent also in solvent resistance, such as.

As piping for automobile brake system, fuel system or hydraulic system, the outer plastic jacket layer is a layer made of thermoplastic material, especially polyamide resin, extruded on the chromate layer on the outer peripheral surface of the inner metal tube Piping characterized by this is known (see, for example, Patent Document 1). However, in this piping, gasohol (low-concentration ethanol mixed gasoline; fuel developed and put to practical use in the United States and Brazil for the purpose of reducing octane number and nitrogen dioxide emissions, etc.) is not adhered after immersion. There was a drawback of sufficient.

As a surface treatment method for a metal tube, a zinc or zinc-nickel plating layer formed on the outer peripheral surface of the metal tube, and a chemical conversion treatment layer mainly composed of a trivalent chromium compound and a phosphate compound formed on the plating layer; An epoxy resin intermediate layer made of an epoxy resin paint to which a rust preventive pigment mainly composed of a condensed phosphate and a magnesium silicate compound formed on the chemical conversion treatment layer is added, and the epoxy resin intermediate layer There is known a surface treatment method for a metal tube that forms a resin layer (a layer made of a polyvinyl fluoride resin, a polyvinylidene fluoride resin, or a polyamide resin) formed on the surface (for example, see Patent Document 2). However, this method does not contain hexavalent chromium in the treatment and coating, but it contains trivalent chromium and is not completely chromium-free as required by the market. Adhesion after immersion of gasohole is insufficient. There was a drawback.

Also related to a conduit comprising a metal inner pipe, an aluminum coat formed on the outer surface of the inner pipe, and a polyamide layer connected to the aluminum coat for liquids used in automobiles, particularly fuel and pressure fluid As a method, a surface treatment layer not containing chromium and / or a primer coat using a commercially available polyamide primer is known between an aluminum coat and a polyamide resin layer (see, for example, Patent Document 3). . However, there is a drawback that the gasohol resistance (coating adhesion test after gasohol immersion) is insufficient.

It is also known that low temperature curability and high adhesion can be obtained by adding an epoxy resin to a polyamideimide resin (see, for example, Patent Document 4). However, there has been a drawback that the coating film is brittle and bending workability is insufficient.

In addition, a binder component (A) containing an epoxy resin and an amino resin and / or a phenol resin on the surface to be coated with a metal object; a binder component (B) containing a polyester resin, an epoxy resin and a phenol resin, and an α-olefin · α, A primer composition obtained by blending an inorganic rust inhibitor with at least one binder component selected from the group consisting of a binder component (C) containing a β-ethylenically unsaturated carboxylic acid copolymer resin is obtained. A thermoplastic resin coating (any of a vinyl fluoride resin coating, a vinylidene fluoride resin coating, or a polyamide resin coating) is coated through the primer coating layer formed to form a thermoplastic resin coating. A characteristic metal object coating method is known (see, for example, Patent Document 5). However, this method has a drawback that the multi-layer coating film coated with the polyamide resin-based paint has insufficient gasohol resistance.

JP-T 9-509723 JP 2003-194288 A JP 2003-343767 A JP-A-9-302226 Republished WO2003-033173

The present invention is excellent in adhesion to metals such as iron and copper, or plated steel plates plated thereon, in particular, galvanized steel plates, and to adherence to a top coat when a polyamide (nylon) resin is used as a top coat. An object of the present invention is to provide a primer composition that can form a primer coating film excellent in gasohol property.

As a result of intensive studies to solve the above problems, the present inventor has obtained a primer composition containing a polyamideimide resin, a solvent-soluble polyamide resin, a solvent-insoluble nylon resin bead, an epoxy resin and a curing agent in a specific ratio. Thus, the present inventors have found that the above-mentioned problems can be solved, and have completed the present invention.
That is, the present invention contains (A) a polyamideimide resin, (B) a solvent-soluble polyamide resin, (C) a solvent-insoluble nylon resin bead, (D) an epoxy resin, and (E) a curing agent. The content ratio of the component (A) is 10 to 30% by mass with respect to the total mass of the resin solids of the component A), the component B, the component C, the component D, and the component E. ) The content ratio of the component is 5 to 20 mass%, the content ratio of the (C) component is 59 to 15 mass%, the content ratio of the (D) component is 10 to 30 mass%, and the content ratio of the (E) component is 1 to 1 mass%. The primer composition is characterized by being 20% by mass.
Moreover, this invention provides the primer composition whose (E) component is a phenol resin and / or an amino resin in the said primer composition.
The present invention also provides a primer composition, wherein the primer composition is a primer composition used as an undercoat paint for a polyamide resin coating.

  The primer composition of the present invention is excellent in adhesion to metals such as iron and copper, or plated steel plates plated thereon, in particular, galvanized steel plates, and a top coat film when a polyamide (nylon) resin is used as a top coat film. In addition, it is possible to form a primer coating film that exhibits excellent performance and particularly gasohol performance.

The present invention is a primer composition containing a polyamideimide resin, a solvent-soluble polyamide resin, a solvent-insoluble nylon resin bead, an epoxy resin, and a curing agent.
The resin acid value of the polyamide-imide resin (A) used in the present invention is preferably 30 mgKOH / g or less, more preferably 10 mgKOH / g or less. When the acid value exceeds 30 mgKOH / g, the storage stability at 50 ° C. may decrease, which is not preferable.
Moreover, 9,000-28,000 are preferable and, as for the number average molecular weight of the polyamideimide resin of (A) component, More preferably, it is 12,000-25,000. If the number average molecular weight is less than 9,000, the gasohol property may be deteriorated, and if it exceeds 28,000, the coating workability may be deteriorated. Further, the polyamide-imide resin as the component (A) is preferably a solvent-soluble one.
The role of the component (A) in the present invention is to suppress the swelling of the coating film during gasohol immersion and to ensure the adhesion of the primer coating film after gasohol immersion.

There is no restriction | limiting in particular about the manufacturing method of a polyamidoimide resin, A various manufacturing method is mentioned. Polyamideimide resin is produced by a known production method, specifically, a trivalent or higher polycarboxylic acid (a) having an acid anhydride group (a), a divalent dicarboxylic acid (b), an aromatic isocyanate or an aromatic. It is obtained by reacting diamine (c) and lactam (d) in an organic polar solvent. As a ratio of (a) to (d), for example, the mixing ratio (a) / (b) of (a) and (b) is preferably 4/6 to 9/1 in terms of equivalent ratio, and the ratio of (c) Is preferably a ratio of the total number of carboxyl groups and amino groups of (a) and (b) of 8 to 16, and the ratio of (d) is 0. 0 to the total mass of (a), (b) and (c). 1-20 mass% is preferable. When the aromatic diisocyanate is used in the presence of an organic polar solvent in the temperature range of 80 to 150 ° C., the reaction is carried out by heat condensation while removing free generated carbon dioxide from the reaction system. The reaction time is appropriately selected depending on the scale of the batch and the reaction conditions employed.

Examples of the organic polar solvent include N-methyl-2-pyrrolidone, N, N-dimethylformamide, N, N-dimethylacetamide, dimethyl sulfoxide, γ-butyrolactone, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether and the like alone or 2 It can be used in combination of two or more species, and the amount used is preferably 1.0 to 5.0 times (mass) of the polyamideimide resin to be produced. When an aromatic diisocyanate is used after the synthesis of the polyamideimide resin, the isocyanate group at the end of the resin can be further blocked with a blocking agent such as alcohols, lactams or oximes.

Commercially available polyamide-imide resins include Viromax HR11NN, Viromax 13NX, Viromax 14ET (all manufactured by Toyobo Co., Ltd.), HI-405-30, HPC-5000, HPC-5010S, HPC-5020. , HPC-5030, HPC-6000, HPC-6100, HPC-7200, HPC-9000 (all manufactured by Hitachi Chemical Co., Ltd.).
The polyamideimide resin of component (A) may be used alone or in combination of two or more.

The solvent-soluble polyamide resin of the component (B) of the present invention is not particularly limited as long as it is a polyamide resin soluble in the solvent in the primer composition. The role of the (B) component solvent-soluble polyamide resin ensures compatibility with the (C) component solvent-insoluble nylon resin beads, and ensures compatibility with the (D) component and (E) component. Thus, the compatibility between the solvent-insoluble nylon resin beads, the epoxy resin, and the curing agent is enhanced, and the strength of the coating film is enhanced.
Solventable polyamide resins include polyamide 6 by ring-opening polymerization of ε-caprolactam, polyamide 66 by condensation polymerization of hexamethylenediamine and adipic acid, polyamide 610 by condensation polymerization of hexamethylenediamine and sebacic acid, and 11-aminoundecanoic acid. Among the polyamide 11 by condensation polymerization, ring-opening polymerization of ω-laurolactam or polyamide 12 by condensation polymerization of 12-aminododecanoic acid, and the like, resins soluble in a solvent can be mentioned.
Solvent-soluble polyamide resins that can be used as the commercially available component (B) include PA-100, PA-100A, PA-102A, PA-200, PA-201, and TPAE-12 (all of which are Fuji Chemical Industries). Etc.).
The solvent-soluble polyamide resin (B) may be used alone or in combination of two or more.

The solvent-insoluble nylon resin beads (C) used in the present invention may be nylon resin beads that are insoluble in the solvent in the primer composition. The melting temperature of the component (C) solvent-insoluble nylon resin beads is preferably 150 ° C. or higher, more preferably 170 ° C. or higher. If the melting temperature is less than 150 ° C., the thermal stability of the resin during high-temperature baking tends to decrease, which is not preferable.
The solvent-insoluble nylon resin beads of component (C) are preferably nylon resin beads insoluble in solvents such as alcohols, esters and ketones.
The average particle size of the solvent-insoluble nylon resin beads of component (C) is preferably 5 to 100 μm, more preferably 10 to 50 μm. If the average particle size is less than 5 μm, the viscosity of the coating tends to be high, which is not preferred.
The role of the solvent-insoluble nylon resin beads of the component (C) in the present invention is to ensure adhesion between the primer coating and the top coating, particularly the polyamide resin coating.

Solvent-insoluble nylon resin beads include polyamide 6 by ring-opening polymerization of ε-caprolactam, polyamide 66 by condensation polymerization of hexamethylenediamine and adipic acid, polyamide 610, 11-aminoundecane by condensation polymerization of hexamethylenediamine and sebacic acid. Examples thereof include polyamide 11 by acid condensation polymerization, polyamide 12 by ring-opening polymerization of ω-laurolactam or condensation polymerization of 12-aminododecanoic acid.
Examples of commercially available solvent-insoluble nylon resin beads include Rilsan Fine Powder D30 NATUREL, Rilsan Fine Powder D40 NATUREELL, Rilsan Fine Powder Powder D50 NATURE1N13501, Olgasol 1002 , Arkema Co., Ltd.), SNP powder 13, SNP powder 19 (all manufactured by Metal Color Co., Ltd.), A1020LP (manufactured by Unitika Co., Ltd.), and the like.
The solvent-insoluble nylon resin beads (C) may be used singly or in combination of two or more.

30-250 mgKOH / g is preferable and, as for the epoxy group value of the epoxy resin of (D) component used for this invention, More preferably, it is 50-130 mgKOH / g. When the epoxy group value exceeds 250 mgKOH / g, the adhesion to the plated steel sheet tends to decrease, and when it is less than 30 mgKOH / g, the coating workability tends to decrease.
The role of the epoxy resin of component (D) in the present invention is to ensure the adhesion between the primer coating and the plated steel sheet.

As an epoxy resin used for this invention, what has 2 or more of epoxy groups in 1 molecule is preferable, and conventionally well-known things, such as a liquid epoxy and a solid epoxy resin, can be especially used without a restriction | limiting. When a solid epoxy resin is used, the resin is dissolved or dispersed in an organic solvent that can be dissolved or dispersed.

As commercially available epoxy resins, jER1001, jER1002, jER1003, jER1055, jER1004, jER1007 (all manufactured by Japan Epoxy Resins Co., Ltd.), Epotot YD-134, Epotot YD-011, Epotot YD-012, Epotot YD-013, Epototo YD-014, Epototo YD-017, Epototo YD-7011R, Epototo YD-907 (all manufactured by Toto Kasei Co., Ltd.), E. R662E, D.R. E. R663UE, D.E. E. R664U, D.R. E. Examples thereof include bisphenol / epichlorohydrin type epoxy resins such as R667E (both manufactured by Dow Chemical Co.).
(D) The epoxy resin of a component may be used individually by 1 type, and may use 2 or more types together.

As the curing agent of the component (E) used in the present invention, a phenol resin and an amino resin are preferable, and each may be used alone or in combination.
The role of the curing agent of the component (E) in the present invention is to react with the resin component in the compounded resin to obtain a thermosetting coating film.
As a number average molecular weight of a phenol resin, 300-1,500 are preferable, More preferably, it is 400-1,000. When the number average molecular weight is less than 300, the bendability of the cured coating film tends to decrease, and when it exceeds 1,500, the storage stability of the paint at 50 ° C. tends to decrease, which is not preferable.

The phenol resin is obtained by reacting phenols with formaldehydes. Examples of the phenols used for obtaining the phenol resin include phenol, methylphenol, p-ethylphenol, pn-propylphenol, p-isopropylphenol, pn-butylphenol, p-tert-butylphenol, p. One benzene ring in one molecule such as -tert-amylphenol, o-cresol, m-cresol, p-cresol, p-cyclohexylphenol, p-octylphenol, p-nonylphenol, 3,5-xylenol, resorcinol, catechol Phenols having one; Phenols having two benzene rings in one molecule such as phenyl o-cresol and p-phenylphenol; bisphenol A, bisphenol F and the like can be mentioned. It can also be used combined. Examples of formaldehydes include formaldehyde, paraformaldehyde, and trioxane.

In the reaction between the phenols and formaldehydes, inorganic acids, organic acids, organic acid metal salts, and the like can be used as catalysts.
The phenol may be a resol type phenol resin or a novolac type phenol resin. Among them, a resol type phenol resin is preferable. Moreover, the phenol resin modified | denatured suitably with the natural resin, the acrylic resin, the polyester resin, etc. may be sufficient as needed. The above phenol resins may be used alone or in combination of two or more.

Moreover, as a weight average molecular weight of an amino resin, 600-20,000 are preferable, More preferably, it is 1,000-10,000. When the weight average molecular weight is less than 800, the bending property of the cured coating film tends to be lowered, and when it exceeds 20,000, the gasohol property tends to be lowered, which is not preferable.
Examples of amino resins include melamine resins, urea resins, benzoguanamine resins, acetoguanamine resins, steroguanamine resins, spiroguanamine resins, methylolated amino resins obtained by reaction of aldehydes with amino components such as dicyandiamide. May be modified with epoxy resin, acrylic resin, polyester resin or the like. From the viewpoint of bending workability, melamine resin is preferable. The amino resins may be used alone or in combination of two or more.
(E) The hardening | curing agent of a component may be used individually by 1 type, and may use 2 or more types together.

Component (A) Polyamideimide resin, Component (B) Solvent-soluble polyamide resin, Component (C) Solvent-insoluble nylon resin beads, Component (D) Epoxy resin, Component (E) Curing agent primer The content ratio in the composition is (A) component, (B) component, (C) component, (D) component, and (E) component based on the total mass of resin solids of (A) component is 10 to 10. 30 mass%, (B) component is 5-20 mass%, (C) component is 59-15 mass%, (D) component is 10-30 mass%, and (E) component is 1-20 mass%.
More preferably, (A) component is 15-22 mass%, (B) component is 10-15 mass% (C) component is 50-30 mass%, (D) component is 15-25 mass%, (E) A component is 3-13 mass%. The sum of the content ratios of component (A), component (B), component (C), component (D) and component (E) is 100% by mass. In addition, resin solid content says the heating residue measured by the method described in JISK5601-1-2.

When the component (A) is less than 10% by mass, the adhesion (secondary adhesion) between the primer coating and the top coating after dipping into gasohol is reduced, and when it exceeds 30% by mass, the primer coating and the top coating This is not preferable because the initial adhesion (primary adhesion) is reduced.
In addition, when the component (B) is less than 5% by mass, the initial adhesion (primary adhesion) between the primer coating and the top coat decreases, and when it exceeds 20% by mass, the primer coating and the top coat after immersion in gasohol Adhesiveness (secondary adhesion) with the coating is unfavorable.

When the component (C) is less than 15% by mass, the primary adhesion between the primer coating and the top coating decreases, and when it exceeds 59% by mass, the secondary adhesion between the primer coating and the top coating after dipping in gasohol decreases. It is not preferable.
When the component (D) is less than 10% by mass, the adhesion between the primer coating film and the plated steel sheet is lowered, and when it exceeds 30% by mass, the bending workability is undesirably lowered.
When the component (E) is less than 1% by mass, the adhesion between the primer coating and the top coat after dipping into gasohol is lowered, and when it exceeds 20% by mass, the bending workability is undesirably lowered.

A rust preventive pigment can be blended with the primer composition of the present invention for the purpose of improving the corrosion resistance. As the rust preventive pigment, a rust preventive pigment usually used for an undercoat paint can be used.
Specific examples of rust preventive pigments include chromium-based pigments such as zinc chromate and strontium chromate, and non-polluting rust-preventing pigments that do not contain chromium. The use of rust pigments is preferred.
Examples of pollution-free rust preventive pigments include zinc phosphate rust preventive pigments, magnesium phosphate rust preventive pigments, aluminum phosphate rust preventive pigments, calcium phosphate rust preventive pigments, zinc phosphite rust preventive pigments, and magnesium phosphite Anti-corrosion pigments, calcium phosphite anti-corrosion pigments, aluminum phosphite anti-corrosion pigments, etc. Condensate phosphate anti-corrosion pigments, pigments whose surfaces are treated with metal compounds; zinc molybdate anti-corrosion pigments Zinc rust preventive pigments such as cyanamide zinc rust preventive pigments and cyanamide zinc calcium rust preventive pigments; silica and the like. These can be used alone or in admixture of two or more.

In the primer composition of the present invention, pigments conventionally used for paints, such as inorganic pigments other than rust preventive pigments, organic pigments and processed pigments, can be blended as necessary. Examples of the organic pigment include azo lake pigments, phthalocyanine pigments, indigo pigments, perylene pigments, quinophthalone pigments, dioxazine pigments, quinacridone pigments, isoindolinone pigments, metal complex pigments, and the like. Examples of inorganic pigments include yellow iron oxide, red pepper, titanium dioxide, and carbon black.
If necessary, scaly pigments such as aluminum pigments and pearl pigments can also be blended. These pigments are not particularly limited, and can be used alone or in admixture of two or more.

The primer composition of the present invention is preferably used by dissolving or dispersing the components (A), (B), (D) and (E) in an organic solvent. Examples of the organic solvent include hexane, heptane, isooctane, unsaturated aliphatic hydrocarbon, benzene, toluene, xylene, (o-, m-, p-) cyclohexane, dioxane, tetrahydrofuran, cellosolve, methyl cellosolve, butyl cellosolve, and methyl carbitol. 2-methoxyethanol 2-butoxyethanol diethylene glycol, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, diethylene glycol monoethyl ether acetate, triethylene glycol monomethyl ether, 1-methoxy-2-propanol, 1-ethoxy-2-propanol, dipropylene Glycol monomethyl 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 monoacetate, cellosolve acetate, carbitol acetate, ethyl acetoacetate, pyridine, N-methyl -2-pyrrolidone, formamide, N, N-dimethylformamide, acetamide and the like.

  As a material to which the primer composition of the present invention is applied, a metal plate such as iron or copper or a plated steel plate plated thereon is preferably used, and a galvanized steel plate is particularly preferable. When applying the primer composition, it is preferable to perform a pre-coating treatment on the surface of the material, and as this pre-coating treatment, any chemical conversion treatment used as a pre-coating metal pretreatment may be used, for example, chromate chemical conversion treatment, Examples include phosphate chemical conversion treatment and composite oxide film treatment.

The primer composition of the present invention can be applied by various coating methods, for example, a roll coater, a flow coater, dipping, spraying or the like. Of these, coating with a roll coater is preferable in terms of film thickness control and uniformity. The coating film to which the primer composition is applied is usually baked at 100 to 300 ° C. under a curing condition of 5 seconds to 5 minutes. May be cured at 120 to 260 ° C. under curing conditions of 15 to 120 seconds.
The dry coating thickness of the primer coating obtained by applying the primer composition of the present invention is usually preferably in the range of 1 to 10 μm, more preferably 3 to 7 μm.

As the film to be coated on the primer film of the present invention, a polyamide (nylon) resin film is preferable in terms of adhesion. The polyamide (nylon) resin includes polyamide 6 by ring-opening polymerization of ε-caprolactam having the same composition as the solvent-insoluble nylon resin beads used in the primer composition of the present invention, and polyamide 66 by condensation polymerization of hexamethylenediamine and adipic acid. And polyamide 610 by condensation polymerization of hexamethylenediamine and sebacic acid, polyamide 11 by condensation polymerization of 11-aminoundecanoic acid, polyamide 12 by ring-opening polymerization of ω-laurolactam or condensation polymerization of 12-aminododecanoic acid, and the like. Can be mentioned. Examples of the method for forming a polyamide resin film include a method of forming a film by heating and melting at a temperature equal to or higher than the melting point of the polyamide resin to form a film. The method is mentioned.
The film thickness of the polyamide resin coating is preferably 50 to 200 μm, more preferably 80 to 150 μm.

Hereinafter, the present invention will be described more specifically with reference to production examples, examples and comparative examples. The present invention is not limited to these examples. Hereinafter, unless otherwise specified, “part” and “%” mean “part by mass” and “% by mass”, respectively. In Tables 1 to 3, the unit of the numerical value indicating the blending amount of each component is part by mass.
In the examples and comparative examples, each item was evaluated by the following method.

<Coating workability and coating film evaluation method>
(Primer composition painting workability)
The primer composition was diluted with a diluting solvent (mixed solvent of N-methylpyrrolidone / isophorone = 50/50 (mass ratio)). 4 (25 ° C.) for 60 seconds, and the diluted primer composition has a dry coating thickness of 4 to 6 μm on the surface of an electrogalvanized steel sheet (length 100 mm, width 67 mm, thickness 0.3 mm). Paint the bar coater. The skin of the primer coating film at this time was evaluated according to the following criteria, and the coating workability of the primer composition was evaluated.
A: No problem.
○: No problem in practical use.
X: It becomes round skin and has a problem in practical use.

The primer composition was diluted with a primary adhesion performance dilution solvent (mixed solvent of N-methylpyrrolidone / isophorone = 50/50 (mass ratio)). 4 (25 ° C.) is diluted to 60 seconds, and the diluted primer composition has a dry coating thickness of 4 to 6 μm on the surface of an electrogalvanized steel sheet (length 100 mm, width 67 mm, thickness 0.3 mm). After coating with a bar coater as described above, it is immediately baked and cured at 260 ° C. for 40 seconds. At this time, a portion where the primer composition is not coated is prepared in a length of about 40 mm.
Next, nylon pellets (trade name: Rilsan B BMF O (manufactured by Arkema)) are melted at 300 ° C. and coated with an applicator so as to be 100 to 110 μm. At this time, a portion not coated with the primer composition was also coated at the same time to obtain a test plate as a continuous film. Cut the coating film with a width of 10 mm in the longitudinal direction of the test plate obtained, pull the nylon coating film from the part where the primer composition is not coated at a constant speed, and peel the part where the primer composition is coated Was evaluated according to the following criteria.

(I) Adhesion between the plated steel sheet and the primer coating film A: The nylon coating film breaks at the primer coating film site.
○: After the cohesive failure or interfacial peeling at the primer coating portion, the nylon coating breaks.
X: Although there is interfacial peeling between the plated steel sheet and the primer coating, the nylon coating does not break.

(Ii) Initial adhesion between the primer coating and the top coating The test plate was prepared in the same manner as the adhesion (primary adhesion) between the plated steel plate and the primer coating, and the initial adhesion between the primer coating and the nylon coating. The property (primary adhesion) was evaluated according to the following criteria.
A: The nylon coating breaks at the primer coating.
○: Nylon paint film breaks after cohesive failure or interfacial peeling at the primer paint film site.
X: Although there is interfacial peeling between the primer coating and the nylon coating, the nylon coating does not break.

(Bendability)
The primer composition was diluted with a diluting solvent (mixed solvent of N-methylpyrrolidone / isophorone = 50/50 (mass ratio)). 4 (at 25 ° C.) for 60 seconds, and the diluted primer composition is formed on the surface of an electrogalvanized steel sheet (length 100 mm, width 67 mm, thickness 0.3 mm) so that the dry coating thickness becomes 4 to 6 μm. After coating with a bar coater, it was immediately baked and cured at 260 ° C. for 40 seconds to obtain a test plate for bendability.
As a bendability test, a test piece cut to a width of 5 cm at a room temperature of 20 ° C. does not sandwich anything at 0T, and at 1T, a single coated plate is the same as the test piece, and at 2T, a coated plate is the same as the test piece. In the 4T, a test was conducted in which the same coated plate was placed on the inner side of the four sheets with the scissor coating on the outside and the 180 degree contact bending was performed. The bendability was evaluated based on the results of the bending test according to the following criteria.
(Double-circle): There is no crack generation in 4T.
○: There is a slight crack at the time of 4T bending, but there is no practical problem.
X: Cracks are generated and there are practical problems.

(Adhesion between primer coating and top coating after gasohol immersion (secondary adhesion))
The primer composition was diluted with a diluting solvent (mixed solvent of N-methylpyrrolidone / isophorone = 50/50 (mass ratio)). 4 (25 ° C.) is diluted to 60 seconds, and the diluted primer composition has a dry coating thickness of 4 to 6 μm on the surface of an electrogalvanized steel sheet (length 100 mm, width 67 mm, thickness 0.3 mm). After coating with a bar coater as described above, it is immediately baked and cured at 260 ° C. for 40 seconds. At this time, a portion where the primer composition is not coated is prepared in a length of about 40 mm.

Next, nylon pellets (trade name: Rilsan B BMF O (manufactured by Arkema)) are melted at 300 ° C. and coated with an applicator so as to be 100 to 110 μm. At this time, a portion not coated with the primer composition was also coated at the same time to obtain a test plate as a continuous film. The obtained test plate was immersed in gasohol at 20 ° C. for 120 hours, then left at room temperature for 1 hour, cut into the coating film with a width of 10 mm in the longitudinal direction, and nylon from the part where the primer composition was not coated. The coating film was pulled at a constant speed, and the peeled state of the portion where the primer composition was applied was evaluated according to the following criteria.
A: The nylon coating breaks at the primer coating.
○: Nylon paint film breaks after cohesive failure or interfacial peeling at the primer paint film site.
X: There is interfacial peeling or cohesive failure at the primer coating, but the nylon coating does not break.

Production Example of Primer Composition P-1
In the disperser, 381.8 parts of Bilomax HR11NN (polyamideimide resin, trade name, manufactured by Toyobo Co., Ltd., number average molecular weight 15,000, resin solid content 15%), barium sulfate SS-50 (extreme pigment, trade name) 9.5 parts, manufactured by Sakai Chemical Co., Ltd., matting agent HK125 (rust preventive pigment, trade name, manufactured by Degussa) 22.3 parts, N-methylpyrrolidone 50 parts, and isophorone 50 parts, particle size Disperse until 30 μm or less. When the desired particle size is reached, stop the dispersion and Rilsan
Fine Powder D30 NATUREL (Nylon resin beads insoluble in solvent, trade name, manufactured by Arkema Corp., average particle size 25 μm) 140 parts, N-methylpyrrolidone 50 parts, isophorone 50 parts in a solvent mixed with PA-100 38.2 parts of soluble polyamide resin, trade name, manufactured by Fuji Kasei Kogyo Co., Ltd., resin solid content 100%) and jER1001 (epoxy resin, trade name, manufactured by Japan Epoxy Resins Co., Ltd., epoxy value 118, resin solid content) 100%) solution obtained by dissolving 57.3 parts, Shonorol CKS-704 (phenol resin, Showa High Polymer Co., Ltd., number average molecular weight 430, resin solid content 59%) 21.6 parts, Uban 80S ( Melamine resin, trade name, manufactured by Mitsui Chemicals, Inc., weight average molecular weight 3700, resin solid content 50%) 25.5 parts, N-methylpi Pyrrolidone 51.9 parts, take out the addition of isophorone 51.9 parts, thoroughly stirred to obtain P-1 of the production example of the primer composition shown in Table 1. In addition, the numerical value of the heating residue described in the column of the characteristic value of the primer composition shown in Tables 1-3 shows the content rate (mass%) of the heating residue with respect to the total mass of the primer composition. The breakdown of the heating residue is resin and pigment, and the total content of the resin and pigment content (mass%) gives the heating residue content (mass%).

Production Examples of Primer Composition P-2 to P-3, P-5 to P-23
In the same manner as Primer Production Example P-1, P-2 to P-3 and P-5 to P-23 shown in Tables 1 to 3 were obtained.

Production Example of Primer Composition P-4
224 parts of Viromax HR13NX (polyamideimide resin, trade name, manufactured by Toyobo Co., Ltd., number average molecular weight 10000, resin solid content 30%), Olgasol 2002 ES3 NAT3 (nylon resin beads insoluble in solvent, manufactured by Arkema, 128 parts of an average particle diameter of 40 μm), 50 parts of N-methylpyrrolidone and 50 parts of isophorone are charged and stirred sufficiently. Next, PA-100 (polyamide resin soluble in a solvent, trade name, manufactured by Fuji Kasei Kogyo Co., Ltd., resin solid content 100%) in a solvent obtained by mixing 50 parts of N-methylpyrrolidone and 50 parts of isophorone 35. 2 parts, jER1001 (epoxy resin, trade name, manufactured by Japan Epoxy Resin Co., Ltd., epoxy value 118, resin solid content 100%), a solution prepared by dissolving 64 parts, Shonor CKS-704 (phenol resin, Showa Polymer Co., Ltd.) ), Number average molecular weight 430, resin solid content 59%) 21.7 parts, Uban 20SB (melamine resin, manufactured by Mitsui Chemicals, Inc., weight average molecular weight 5780, resin solid content 50%) 25.6 parts, N- 150.8 parts of methylpyrrolidone and 150.7 parts of isophorone were added and stirred sufficiently to obtain P-4 as a primer composition production example shown in Table 1.

Example 1
Using the primer composition production example P-1, the workability of the primer composition was evaluated by the method described in (Coating workability of primer composition), and the results are shown in Table 4.
Next, the bendability was evaluated by the method described in (Bendability), and the results are shown in Table 4. Next, the adhesion was evaluated by the method described in (Adhesion between the plated steel sheet and the primer coating (primary adhesion)) and (Initial adhesion between the primer coating and the top coat (primary adhesion)). The results are shown in Table 4. Furthermore, the adhesion was evaluated by the method described in (Adhesion between primer coating and top coating after immersion in gasohol (secondary adhesion)), and the results are shown in Table 4.

Examples 2-14, Comparative Examples 1-9
Each item was evaluated in the same manner as in Example 1, and the results are summarized in Tables 4 and 5.

The numbers in parentheses in the table are shown below.
1): Viromax HR11NN: Polyamideimide resin, trade name, manufactured by Toyobo Co., Ltd., number average molecular weight 10,000, resin solid content 15% by mass
2): Viromax HR13NX: Polyamideimide resin, trade name, manufactured by Toyobo Co., Ltd., number average molecular weight 10,000, resin solid content 30% by mass
3): HI-405-30: Polyamideimide resin, trade name, manufactured by Hitachi Chemical Co., Ltd., number average molecular weight 19,000, resin solid content 30% by mass
4): PA-100: Solvent-soluble polyamide resin, trade name, manufactured by Fuji Kasei Kogyo Co., Ltd., resin solid content 100%
5): PA-102A: Solvent-soluble polyamide resin, trade name, manufactured by Fuji Kasei Kogyo Co., Ltd., resin solid content 100%

6): PA-200: Solvent-soluble polyamide resin, trade name, manufactured by Fuji Kasei Kogyo Co., Ltd., resin solid content 100%
7): PA-200: Solvent-soluble polyamide resin, trade name, manufactured by Fuji Kasei Kogyo Co., Ltd., resin solid content 100%
8): Rilsan Fine Powder D30 NATURER: Solvent-insoluble nylon resin beads, trade name, manufactured by Arkema, average particle size 25 μm
9): Orgasol 2002ES4NAT3: Nylon resin beads insoluble in solvent, trade name, manufactured by Arkema, average particle size of 40 μm
10): Orgasol 2002ES3NAT3: Nylon resin beads insoluble in solvent, trade name, manufactured by Arkema, average particle size of 30 μm

11): jER1001: Epoxy resin, trade name, manufactured by Japan Epoxy Resin Co., Ltd., epoxy value 118, resin solid content 100% by mass
12): jER1002: Epoxy resin, trade name, manufactured by Japan Epoxy Resin Co., Ltd., epoxy value 87, resin solid content mass 100%
13): jER834: Epoxy resin, trade name, manufactured by Japan Epoxy Resin Co., Ltd., epoxy value 226, resin solid content mass 100%
14): YD-907: Epoxy resin, trade name, manufactured by Tohto Kasei Co., Ltd., epoxy value 38, resin solid content mass 100%
15): Shounol CKS-704: phenol resin, Showa High Polymer Co., Ltd., number average molecular weight 430, resin solid content 59% by mass

16): Shounol CRG-951: phenol resin, manufactured by Showa Polymer Co., Ltd., number average molecular weight 750, resin solid content 100% by mass
17): Uban 80S: Melamine resin, trade name, manufactured by Mitsui Chemicals, Inc., weight average molecular weight 3,700, resin solid content 50% by mass
18): Yuban 20SB: Melamine resin, trade name, manufactured by Mitsui Chemicals, Inc., weight average molecular weight 5,780, resin solid content 50% by mass
19): Uban 122: Melamine resin, trade name, manufactured by Mitsui Chemicals, Inc., weight average molecular weight 1560, resin solid content 60% by mass
20): Barium sulfate SS-50: extender pigment, trade name, manufactured by Sakai Chemical Co., Ltd.
21): matting agent HK-125: rust preventive pigment, trade name, manufactured by Degussa 22): Taipure R-706: titanium oxide, trade name, manufactured by DuPont,
23): Carbine black FW200: Carbon black, trade name, manufactured by Degussa 24): jER828: Epoxy resin, trade name, manufactured by Japan Epoxy Resin Co., Ltd., epoxy value 297, resin solid content 100% by mass

As shown in Examples 1 to 14 in Table 3, the primer composition of the present invention has a performance of a level that is practically satisfactory in any case within the scope of the present invention.
However, when the content ratio of the polyamideimide resin, the solvent-soluble polyamide resin, and the solvent-insoluble nylon resin beads is outside the range of claims, the initial adhesion between the primer coating and the top coating as shown in Comparative Examples 1 to 5 Alternatively, the adhesion between the primer coating and the top coating after immersion in gasohol becomes poor. Further, when the content ratio of the epoxy resin is outside the range of claims, as shown in Comparative Examples 6 and 7, the adhesion between the primer coating film and the plated steel sheet becomes poor or the bendability becomes poor. Furthermore, when the content ratio of the curing agent component is outside the range of claims, as shown in Comparative Examples 8 and 9, the adhesion or bendability between the primer coating and the top coating after immersion in gasohol becomes poor.

  As described above, if each component of the primer composition is within the scope of the claims of the present invention, the primer composition is excellent in coating workability, adhesion between the plated steel sheet and the primer coating (primary adhesion), primer coating, Undercoat paint for polyamide resin coating that can form a primer coating excellent in initial adhesion (primary adhesion), bendability, and adhesion between the primer coating and the overcoat coating (secondary adhesion) with the top coating. A useful primer composition is obtained.

Claims (3)

(A) Polyamideimide resin, (B) Solvent-soluble polyamide resin, (C) Solvent-insoluble nylon resin beads, (D) Epoxy resin, and (E) Curing agent, (A) component, (B ) Component, (C) component, (D) component, and (E) component based on the total mass of resin solids, the content ratio of (A) component is 10 to 30% by mass, and the content ratio of (B) component is 5 to 20 mass%, the content ratio of component (C) is 59 to 15 mass%, the content ratio of component (D) is 10 to 30 mass%, and the content ratio of component (E) is 1 to 20 mass%. A primer composition. The primer composition according to claim 1, wherein the component (E) is a phenol resin and / or an amino resin. The primer composition according to claim 1 or 2, wherein the primer composition is a primer composition used as an undercoat paint for a polyamide resin film.