JP2001219122A - Article with fluororesin coating film and manufacturing method there for - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an article with a fluororesin costing film having an outstanding adhesion by forming a primer layer having a sufficient adhesion to a top cost layer and formed on the surface of a base material such as metal, glass or ceramic. SOLUTION: In the article with the fluorescing coating film comprising the top coat layer formed on the base material through the primer layer, the primer layer is formed of a primer composition obtained by uniformly dispersing at least one kind of florororsin powder (A) having an average particle diameter which is larger than the coating film thickness of the primer layer and at least one kind of fluororesin powder (B) having an average particle diameter below the coating film, thickness in a liquid medium at a weight ratio of (A):(B) of 10-100:90-0, preferably 10-55:90-45. On the surface of the primer layer, irregularities (Fig. 1) are formed of the fluororesin power (A) and the top coat layer is firmly bonded on the primer layer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an article having a fluororesin coating on the surface of a substrate and a method for producing the article. More specifically, the present invention relates to an article having a fluororesin coating film having excellent adhesion, which is obtained by providing a primer layer having sufficient adhesion to a top coat layer, and a method for producing the article.

[0002]

2. Description of the Related Art Fluororesins have excellent non-adhesiveness and are therefore widely used as surface coatings for articles requiring various non-viscosities, such as household frying pans. However, this excellent property of fluororesin that it does not adhere to other substances means, on the other hand, that it is difficult to adhere to other substances, and that it is not easy to form a fluororesin coating film on the substrate. There's a problem.

[0003] Therefore, when a fluororesin is applied to a metal surface, ceramic, glass surface, or the like, a physical unevenness is formed on the surface of the substrate by sandblasting, etching, or the like, and then a primer having an adhesive property is formed. In general, a method of applying a composition to the surface of a base material to form a primer layer, and bonding the base material and a fluororesin serving as a top coat layer via the primer layer has been widely performed. In this method, the adhesion between the substrate surface and the primer layer includes:
An anchor effect (anchor effect) is used in which the adhesion area between the primer layer and the substrate surface is increased due to the unevenness of the substrate surface and the adhesive strength is improved.

Further, the primer layer must adhere to the surface of a base material such as metal, ceramic, glass or the like, and must also adhere to a fluororesin which is a top coat layer. A method has been used in which a primer composition in which a fluororesin powder as a material and a substance having an adhesive property called a binder resin are uniformly dispersed in a liquid medium is applied to the surface of a substrate. As the fluororesin powder used in the primer composition, conventionally, a fluororesin fine powder having an average particle size of less than 1 μm is generally widely used from the viewpoints of dispersibility, adhesion to the fluororesin powder of the top coat layer, and the like. Was.

[0005]

However, a primer layer formed by such a conventional primer composition comprising only a fluororesin having an average particle size of less than 1 μm is required.
Anchor effect (anchor effect)
Despite showing excellent adhesion to the base material surface due to, the surface of the formed primer layer becomes smooth, it is not possible to obtain an anchor effect on the adhesion surface with the top coat layer, the primer layer and There was a problem that it was not possible to obtain a strong adhesive force with the top coat layer.

Further, since the conventional primer composition generally uses a fluororesin powder having an average particle diameter of less than 1 μm, the average particle diameter of the primer composition during firing of the primer layer is 1 μm.
A phenomenon in which the fluororesin powder having a particle size of less than μm and the binder resin are separated into two layers easily occurs, and there has been a problem that delamination occurs between the primer layer and the top coat layer.
In order to prevent the two-layer separation phenomenon, there is also a method of adding an inorganic fine powder such as silica having an average particle diameter smaller than the thickness of the primer layer to the primer composition, but the adhesive force between the top coat layer and the primer layer is also known. Did not improve.

[0007] The present inventors previously added an inorganic powder having an average particle size equal to or larger than the thickness of a primer layer to a conventional primer composition and uniformly dispersed the same to prevent a two-layer separation phenomenon. A primer having excellent adhesion to the top coat layer due to an anchor effect by forming irregularities on the surface of the primer layer was found, but when the thickness of the top coat layer is thin, the inorganic powder is applied to the surface of the top coat layer. In addition to the problem that the topcoat layer is exposed and the surface smoothness of the topcoat layer cannot be obtained, the problem that the non-adhesiveness of the topcoat layer is reduced occurs.

[0008] The present inventors have prevented the two-layer separation phenomenon during firing of the primer layer, have a primer layer having excellent adhesion to the substrate surface and the top coat layer, and have a top coat layer with a thickness of As a result of repeated studies on a method of providing a fluororesin coating film having excellent surface smoothness and non-adhesiveness of the top coat layer even when it is thin, it contains a fluororesin powder having an average particle size equal to or greater than the thickness of the primer layer. By forming a primer layer with the primer composition and forming a top coat layer made of the fluororesin composition through the primer layer, it is found that an article having a fluororesin coating film having excellent adhesive strength can be obtained, The present invention has been completed.

[0009]

That is, the present invention relates to an article having a fluororesin coating film comprising a primer layer formed on a base material and a top coat layer formed on the primer layer. Has at least one type of fluororesin powder (A) having an average particle size not less than its film thickness,
At least one type of fluororesin powder (B) having an average particle size smaller than the film thickness is added to the mixture at a weight ratio of (A) :( B) of 10 to 10;
An article having a fluororesin coating formed by a primer composition uniformly dispersed in a liquid medium at a ratio of 100: 90 to 0, and a method for producing the article.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS (Substrate) The substrate used in the present invention is not particularly limited, and a substrate such as a metal such as aluminum and stainless steel, glass, ceramic, and a clad material of aluminum and stainless steel is used. be able to. Among metals, a substrate made of stainless steel is more difficult to roughen the surface of the substrate than aluminum, and the use of a primer layer formed of a conventional primer composition results in poor adhesion to the substrate surface. Although it is difficult to obtain an excellent fluororesin coating film, the present invention can form a fluororesin coating film with strong adhesion to such a substrate.

(Fluororesin Powder) In the present invention, the fluororesin powder used for forming the primer layer comprises, as an essential component, at least one kind of fluororesin powder (A) having an average particle size not less than the thickness of the primer layer. contains. Preferably, two kinds of fluororesin powders having different average particle diameters from the fluororesin powder (A) and at least one kind of fluororesin powder (B) having an average particle diameter smaller than the thickness of the primer layer are used.

As the fluororesin powder, (A)
(B) In any fluororesin powder, tetrafluoroethylene polymer (hereinafter referred to as PTFE), tetrafluoroethylene / fluoro (alkyl vinyl ether)
Copolymer (hereinafter, referred to as PFA), tetrafluoroethylene / hexafluoropropylene copolymer (hereinafter, referred to as FE)
P), tetrafluoroethylene / ethylene copolymer (hereinafter, referred to as ETFE), polyvinylidene fluoride (hereinafter, referred to as PVDF), polychlorotrifluoroethylene (hereinafter, PCTFE), and a mixture thereof. More preferably, PT having excellent heat resistance
FE, PFA, FEP and mixtures thereof. The fluororesin powders of (A) and (B) may be the same or different.

The fluororesin powder (A) is used for the purpose of forming irregularities on the surface of the primer layer and for preventing the two-layer separation phenomenon of the primer layer. The average particle size is preferably in the range represented by the following formula. Primer layer thickness ≦ Average particle size of fluororesin powder (A) ≦ (Primer layer thickness + Topcoat layer thickness) That is, the average particle size of the fluororesin powder (A) is determined by the phenomenon of two-layer separation. In order to obtain the effect of prevention, it is sufficient that the thickness is not less than の of the thickness of the primer layer to be formed, but in order to form irregularities on the surface of the primer layer, it is not less than the thickness of the primer layer. When the average particle size is less than the film thickness, no irregularities are formed on the surface of the primer layer, and excellent adhesion between the primer layer and the top coat layer due to the anchor effect cannot be obtained. If the average particle size of the fluororesin powder is larger than (the thickness of the primer layer + the thickness of the topcoat layer), it is not preferable because the surface smoothness of the topcoat layer cannot be obtained. Although the actual particle size varies depending on the thickness of the primer layer, it is particularly preferable that the average particle size is 1 μm or more and 50 μm or less.

The shape of the fluororesin powder is not particularly limited, and may be spherical or irregular, but irregular with excellent anchor effect is particularly preferred.

The fluororesin powder (A) having a particle size equal to or larger than the thickness of the primer layer can be used alone.
More preferably, it is used together with a fluororesin powder (B) having a particle size smaller than the thickness of the primer layer.

The actual average particle size of the fluororesin powder (B) having an average particle size smaller than the thickness of the primer layer varies depending on the thickness of the primer layer, but is preferably 1 μm or less.

That is, the fluororesin powder (A) having an average particle size not less than the thickness of the primer layer prevents the two-layer separation phenomenon of the primer layer, forms irregularities on the surface of the primer layer, and causes the primer layer to have an anchor effect. To obtain excellent adhesion between the top coat layer and the top coat layer, and at the time of firing the top coat layer, there is an action of being compatible with the fluororesin powder of the top coat layer and firmly bonding the primer layer and the top coat layer, On the other hand, the fluororesin powder (B) having an average particle diameter smaller than the thickness of the primer layer is required to coagulate the fluororesin powder (A) in the primer composition in which the binder resin (C) is uniformly dispersed or dissolved. In addition, since they have the function of uniformly dispersing, by using both, unevenness due to the fluororesin powder (A) is uniformly formed on the surface of the primer layer. Fluororesin powder used for primer,
A mixture of the fluororesin powder (A) and the fluororesin powder (B) is used. Even if the (A) and (B) are fluororesins having the same melting point and viscosity, the fluororesin powder having a small particle diameter is first used. However, large-sized particles take a long time to melt to the core, and because the melt viscosity of the fluororesin is high and hard to flow, irregularities due to the large particle size are formed even after firing. .

The weight ratio of (A) :( B) of the fluororesin powder constituting the primer composition is from 10 to 100: 90 to 0, preferably from 10 to 55:90 to 45, and more preferably from 15 to 90. 40: 85-60. When the weight ratio of the fluororesin powder (A) is less than 10% by weight, unevenness sufficient to obtain an anchor effect is not formed on the surface of the primer layer, so that the adhesion between the primer layer and the top coat layer is insufficient. In the case of 55% by weight or more, adhesion of the fluororesin powder (A) to the substrate surface becomes insufficient.

(Binder Resin) The binder resin (C) used for forming the primer layer preferably has heat resistance equivalent to that of a fluororesin powder and has adhesiveness to a base material such as metal, glass, and ceramic. Particularly preferred as such a binder resin are a polyimide resin (hereinafter referred to as PI) and a polyamideimide resin (hereinafter referred to as PA).
I), polyphenylene sulfide resin (hereinafter, referred to as
PPS), polyether sulfone resin (hereinafter referred to as P
ES) or a mixture thereof.

The binder resin may be dissolved in the liquid medium or may be uniformly dispersed as fine particles in the liquid medium. Liquid media that can be used include water, polar organic solvents, non-polar organic solvents, and mixtures thereof.

When water is used as the liquid medium, it is preferable to add a surfactant to the liquid medium in order to reduce the surface tension of the liquid medium and improve the dispersibility of the binder resin and the fluororesin powder.

When the binder resin is PI, PAI, or PE
S or the like, when relatively easily dissolved in an organic solvent such as N-methylpyrrolidone or a mixture of N-methylpyrrolidone and diacetone alcohol or xylene, etc.
It is preferable to use the binder resin dissolved in a liquid medium. When the binder resin is difficult to dissolve in an organic solvent such as PPS, use water to which a surfactant is added as a liquid medium and convert the binder resin into a liquid. It is preferable to use the resin dispersed uniformly in the medium.

The weight ratio of the binder resin (C) in the fluororesin composition for forming the primer layer and the fluororesin powder [total of (A) and (B)] is (C):
The weight ratio of [(A) + (B)] is 5-50: 95-50
It is preferred that When the amount of the binder resin is less than 5% by weight, the fluororesin powder is not easily adhered to the surface of the base material, which is not preferable.

(Primer Layer) The primer layer is obtained by applying a primer composition, in which a fluororesin powder and a binder resin are uniformly dispersed, to the surface of a base material, followed by drying or baking. The primer layer is usually formed on the surface of a substrate that has been roughened. As shown in FIG. 1, the surface of the obtained primer layer takes a long time to melt the fluororesin powder (A) having an average particle size equal to or larger than the thickness of the primer layer to the core. Since the resin has a high melt viscosity and is difficult to flow, irregularities are formed and the area of adhesion to the top coat layer is increased. Also,
Since the anchor effect can be obtained by this unevenness,
Can be firmly bonded to the top coat layer.

The thickness of the primer layer is preferably equal to or smaller than the particle size of the fluororesin powder, and the film thickness after firing is particularly preferably 5 to 15 μm.
If the thickness of the primer layer is less than 5 μm, the fluororesin powder (A) having an average particle size greater than or equal to the thickness of the primer layer is detached from the primer layer, and a sufficient anchor effect cannot be obtained. . Further, when the thickness of the primer layer exceeds 15 μm, a two-layer peeling phenomenon easily occurs in the primer layer, which is not preferable because the fluororesin coating film is peeled from the substrate.

(Top Coat Layer) The top coat layer in the present invention is formed by forming an arbitrary fluororesin composition, preferably a fluororesin composition having heat fluidity, on the primer layer having the surface irregularities as described above. It is formed by using. The fluororesin powder used for forming the top coat layer may be the same or different from the fluororesin powder (A) or (B) used for the primer layer, but the fluororesin powder having irregularities on the primer layer surface (A ), The fluororesin powder fuses with each other (chemical effect) when firing the top coat layer, in addition to the anchor effect (physical effect) on the primer layer surface, It is more preferable because the top coat layer is firmly adhered.

(Production Method of Fluororesin Coating Film) The article having the fluororesin coating film of the present invention comprises (A) at least one kind of fluororesin powder having an average particle size not less than the thickness of the primer layer; Preparing a primer composition in which at least one kind of fluororesin powder having an average particle diameter smaller than the thickness of the primer layer and (C) a binder resin are uniformly dispersed in a liquid medium at a weight ratio shown below, A): (B) = 10 to 100: 90 to 0, (C): [(A) + (B)] = 5 to 50:95 to 50 This primer composition is applied to the surface of a substrate by any method. Then, by drying or baking at a temperature of about room temperature to about 400 ° C., irregularities due to the fluororesin powder (A) are formed on the surface of the primer layer.
Electrostatic powder coating, spray coating, spin coating, dip coating,
Paint by any coating method such as roller coating,
It is obtained by baking at 350 ° C. to 400 ° C. for 10 to 40 minutes using a conventional apparatus to form a top coat layer. The thickness of the top coat layer varies depending on the application, but is usually 10 μm to 100 μm.

In preparing the primer composition, a fluororesin powder (A) having an average particle size greater than or equal to the thickness of the primer layer and a fluororesin powder (B) having an average particle size less than the thickness of the primer layer ) Was uniformly dispersed in a liquid medium in advance, and even when the binder resin was added or mixed in the liquid medium in which the binder resin was dissolved or uniformly dispersed, the binder resin was dissolved or uniformly dispersed in a powdery state while the fluororesin powder was in a powdery state. You may add and mix directly in a liquid medium.

The primer layer and the top coat layer of the present invention may be formed of a pigment such as carbon, titanium oxide, chromium oxide, iron oxide, mica, or aluminum flake for coloring, or conductive carbon, graphite, or inorganic flake for imparting conductivity. The conductive fibrous composition or the like may contain an inorganic powder such as silicon carbide or aluminum oxide for improving abrasion resistance and hardness.

[0030]

In the article having the fluororesin coating film of the present invention, the surface of the base material made of metal, glass, ceramic or the like and the top coat layer are firmly bonded via the primer layer. Also, since it is difficult to roughen the surface with the conventional method, it is possible to form a fluororesin coating film with a strong adhesive force on a substrate such as stainless steel, which has been difficult to form a coating film. It is effective for fixing rolls for copying machines and printers, rice cookers, kettle pots, kitchen utensils such as hot plates and frying pans, and various industrial fields requiring non-adhesion.

[0031]

The present invention will be specifically described below with reference to examples and comparative examples. The methods for measuring the physical properties of the coating films of the articles obtained in Examples and Comparative Examples are as follows.

(1) Heat Resistance Adhesion Test
After keeping the temperature for 0 hours, the adhesive strength was measured by a tensile tester.

(2) Salt Water-Resistant Adhesion Test An article having a fluororesin coating film was kept at a constant temperature for 24 hours in a 5% saline solution at 80 ° C., and the adhesive strength was measured with a tensile tester.

[0034]

Examples 1-4 PES was mixed in a mixed solvent of n-methylpyrrolidone and diacetone alcohol (weight ratio 2: 1).
(VICTREX manufactured by ICI), PAI (AMOCO
(TORLON), fluororesin powder (B) (FEP)
Powder; average particle size 0.2 μm), fluororesin powder (A)
(PFA powder; average particle size: 23 μm) and aluminum flake were added and mixed at a ratio shown in Table 1, to prepare a primer composition having a viscosity of 1000 to 1500 cps with a B-type viscometer.

The obtained primer composition was subjected to a sandblast treatment (Al2O3 powder having an average particle size of # 60;
5MPa) SUS430 with 15cm length * 10cm width
Apply to the plate so that the film thickness after drying becomes 10 μm,
It dried at 30 degreeC for 30 minutes, and formed the primer layer. Example 3
1 shows an electron micrograph of the surface of the primer layer. Next, PFA powder (MP-10, manufactured by Du Pont-Mitsui Fluorochemicals Co., Ltd.) is electrostatic powder-coated on the primer layer so that the film thickness after firing becomes 50 μm, and fired at 390 ° C. for 30 minutes to form a top. A heat resistant adhesive strength test and a salt water resistant adhesive strength test were performed on an article having a coating layer formed thereon and having the obtained fluororesin coating film. Table 1 shows the results.

[0036]

Comparative Example 1 PES (IC) was mixed in a mixed solvent of n-methylpyrrolidone and diacetone alcohol (weight ratio 2: 1).
I (VICTREX), PI (AMOCO TO)
RLON), fluororesin powder (B) (FEP powder; average particle size: 0.2 μm), and aluminum flake were added and mixed in the proportions shown in Table 1, and mixed with a B-type viscometer at 1000 to 150.
A primer composition having a viscosity of 0 cps was prepared. Using the obtained primer composition, a heat resistance test and a salt water resistance test were performed in the same manner as in Example 1. Table 1 shows the results. FIG. 2 shows an electron micrograph of the surface of the primer layer.

[0037]

[Table 1]

As is clear from the results shown in Table 1 and FIGS. 1 and 2, the primer layer formed of only the fine fluororesin powder (B) having an average particle diameter of 0.2 μm has few irregularities. Fluororesin coatings of the conventional method, which have been coated by heating, can be easily peeled off by heat treatment or salt water treatment. However, primers formed of a fluororesin powder blended with a fluororesin powder (A) having an average particle size not less than the thickness of the primer layer Since the layer has large irregularities, the fluororesin coating film of the present invention using such a primer layer has a strong adhesive force even under severe conditions.

[Brief description of the drawings]

FIG. 1 is a micrograph of the surface of a primer layer in an article having a fluororesin coating film of the present invention.

FIG. 2 is a micrograph of a primer layer surface of an article having a conventional fluororesin coating film.

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[Procedure amendment]

[Submission date] February 9, 2000 (200.2.9)

[Procedure amendment 1]

[Document name to be amended] Drawing

[Correction target item name] All figures

[Correction method] Change

[Correction contents]

FIG.

FIG. 2

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C09D 179/08 C09D 179/08 CA A 181/04 181/04 181/06 181/06 F-term (reference) 4D075 AE03 CA06 CA13 DB04 DB07 DB13 DB14 DC18 DC38 EA02 EA10 EB14 EB16 EB17 EB18 EB37 EB39 EB56 EB57 4F006 AA18 AA39 AA40 AB19 BA01 DA04 4F100 AB04 AK01B AK04B AK04J AK17B AK17C AK17J AK18B AK18J AK49B AK50B AK55B AK57B AL01B AL05B AS00B AT00A BA03 BA07 BA10A BA10C CA23B DD01 DE01B EH46B EH461 EH462 EJ861 EJ862 JK06 JL11 4J038 CB031 CD091 CD121 CD131 KA20 PA07

Claims (5)

[Claims] 1. An article having a fluororesin coating film comprising a primer layer formed on a base material and a top coat layer formed on the primer layer, wherein the primer layer has an average particle size equal to or greater than the film thickness. At least one type of fluororesin powder (A) having a diameter and at least one type of fluororesin powder (B) having an average particle size smaller than the film thickness thereof;
An article having a fluororesin coating formed by a primer composition uniformly dispersed in a liquid medium at a weight ratio of (A) :( B) of 10 to 100: 90 to 0. 2. The fluororesin powder (A) having an average particle size not less than the thickness of the primer layer is not less than 1 μm and not more than (thickness of the primer layer + thickness of the top coat layer). An article having the fluororesin coating film according to claim 1. 3. At least one of the fluororesin powders (A) and (B) is polytetrafluoroethylene, tetrafluoroethylene / perfluoro (alkyl vinyl ether) copolymer, tetrafluoroethylene / hexafluoropropylene copolymer, The article having a fluororesin coating film according to claim 1 or 2, which is a tetrafluoroethylene / ethylene copolymer, polyvinylidene fluoride, polychlorotrifluoroethylene, or a mixture thereof. 4. A fluororesin powder having an average particle size not less than the thickness of a primer layer formed on a substrate, and
A fluororesin powder having an average particle size less than the thickness of the primer layer, and (C) a binder resin, are mixed in a weight ratio of (A) :( B) of 10 to 100: 90 to 0, (C): [(A) +
(B)], a primer composition uniformly dispersed in a liquid medium at a weight ratio of 5 to 50: 95 to 50 is applied to the surface of the base material, and the surface of the primer layer is coated with the fluororesin powder (A). A method for producing an article having a fluororesin coating, comprising forming a top coat layer made of a fluororesin composition on the primer layer after forming the irregularities. 5. The method according to claim 7, wherein the binder resin (C) is a polyimide resin, a polyamideimide resin, a polyphenylene sulfide resin, a polyether sulfone resin, or a mixture thereof.