Fluorine rubber coating composition and coated article

Abstract

To provide a coating composition which enables the achievement of a coating film that is not susceptible to falling off from a base material, while having a low compression set.SOLUTION: A fluorine rubber coating composition comprising a fluorine rubber, a polyol-based vulcanizing agent, an amino group-containing metal compound, and an organic solvent, wherein the total amount of the polyol-based vulcanizing agent and the amino group-containing metal compound is 0.1-4.99 pts.mass relative to 100 pts.mass of the fluorine rubber.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present disclosure relates to fluororubber coating compositions and coated articles. [Background technology]

[0002] Fluororubber, taking advantage of its excellent heat resistance, oil resistance, solvent resistance and chemical resistance, is used not only for moldings but also for coatings. In the latter case, for example, fluororubber is used to paint or impregnate various substrates such as textiles, fibers, metals, plastics, rubber and the like, and is widely used as an industrial material.

[0003] Patent Document 1 describes a coating material containing fluororubber, a polyol-based vulcanizing agent, 15 parts by weight of an amino group-containing metal compound, methyl isobutyl ketone, etc., per 100 parts by weight of fluororubber.

[0004] Patent Document 2 describes a coating material containing fluororubber, a polyol-based vulcanizing agent, propylene glycol diacetate (thickener), methyl isobutyl ketone (good solvent), isoparaffin-based solvent (antifoaming organic liquid), and the like. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2002-338872 [Patent Document 2] Japanese Patent Application Laid-Open No. 2006-070132 Summary of the Invention [Problem to be solved by the invention]

[0006] An object of the present disclosure is to provide a coating composition that provides a coating film that is less likely to chip off a substrate and has a small compression set, as well as a coated article provided with such a coating film. [Means for solving the problem]

[0007] The present disclosure provides a composition comprising a fluororubber, a polyol-based vulcanizing agent, an amino group-containing metal compound, and an organic solvent, The present invention relates to a fluororubber coating composition comprising the polyol-based vulcanizing agent and the amino group-containing metal compound in a total amount of 0.1 to 4.99 parts by mass per 100 parts by mass of the fluororubber.

[0008] The mass ratio of the polyol vulcanizing agent to the amino group-containing metal compound is preferably 1.0:0.1 to 1.0:1.2.

[0009] The metal in the amino group-containing metal compound is preferably at least one selected from the group consisting of Si, Al, Ti and Zr.

[0010] It is preferable that the amount of the polyol-based vulcanizing agent is 0.1 to 3 parts by mass and the amount of the amino group-containing metal compound is 0.1 to 2 parts by mass relative to 100 parts by mass of the fluororubber.

[0011] The fluororubber coating composition preferably further contains a stabilizer.

[0012] The stabilizer is preferably an orthoester compound.

[0013] The fluororubber coating composition preferably further contains a surface conditioner.

[0014] The fluororubber coating composition preferably further contains an antifoaming agent.

[0015] The present disclosure provides a metal plate; a coating film formed from the fluororubber coating composition on one or both sides of the metal plate; The present invention also relates to a coated article characterized in that it has

[0016] The coated article is preferably a fluororubber coated gasket material. [Effects of the Invention]

[0017] According to the present disclosure, it is possible to provide a coating composition that provides a coating film that is less likely to chip off a substrate and has small compression set, as well as a coated article having such a coating film. DETAILED DESCRIPTION OF THE INVENTION

[0018] The present disclosure will be specifically described below. The present disclosure relates to a fluororubber coating composition comprising a fluororubber, a polyol-based vulcanizing agent, an amino group-containing metal compound, and an organic solvent, wherein the polyol-based vulcanizing agent and the amino group-containing metal compound are contained in a total amount of 0.1 to 4.99 parts by mass per 100 parts by mass of the fluororubber. The fluororubber coating composition of the present disclosure contains the above components, and therefore can provide a coating film that is less likely to peel off from the substrate (the coating film is less likely to wear out) and has a small compression set. Therefore, when the coating composition is applied to a sealing material, excellent sealing properties can be obtained. The coating composition of the present disclosure also has excellent coating stability.

[0019] Examples of the fluororubber include vinylidene fluoride [VdF]-based fluororubber, tetrafluoroethylene [TFE] / propylene [Pr]-based fluororubber, TFE / Pr / VdF-based fluororubber, ethylene [Et] / hexafluoropropylene [HFP]-based fluororubber, Et / HFP / VdF-based fluororubber, Et / HFP / TFE-based fluororubber, fluorosilicone-based fluororubber, fluorophosphazene-based fluororubber, etc. Of these, VdF-based fluororubber is preferred. The above fluororubbers can be used alone or in combination of two or more.

[0020] Examples of the VdF-based fluororubbers include VdF / HFP copolymer, VdF / TFE / HFP copolymer, VdF / chlorotrifluoroethylene [CTFE] copolymer, VdF / CTFE / TFE copolymer, VdF / perfluoro(alkyl vinyl ether) [PAVE] copolymer, VdF / TFE / PAVE copolymer, VdF / HFP / PAVE copolymer, VdF / HFP / TFE / PAVE copolymer, VdF / TFE / Pr copolymer, VdF / Et / HFP copolymer, and VdF / copolymer of a fluorine-containing monomer represented by formula (1). Formula (1): CH2=CFRf (1) (wherein Rf is a linear or branched fluoroalkyl group having 1 to 12 carbon atoms)

[0021] The polyol-based vulcanizing agent may be a vulcanizing agent that is commonly used in polyol-vulcanized fluororubbers. Examples of the polyol-based vulcanizing agent include compounds having at least two hydroxyl groups, particularly phenolic hydroxyl groups, in the molecule and having vulcanization properties, and these compounds may be polymer compounds.

[0022] The polyol-based vulcanizing agent may, among others, be a phenol derivative such as bisphenol A, bisphenol AF, or hydroquinone, or a salt thereof; a polyhydroxy compound having two or more enolic hydroxyl groups in the molecule, such as a phenolic resin, or a salt thereof; f 1 (CH2OH)2(R f 1 represents a perfluoroalkyl polyether group. Compounds represented by the following formula: are preferred. As the polyol-based vulcanizing agent, in addition to the above, any commercially available polyol-based vulcanizing agent for fluororubber can be used. The polyol vulcanizing agent can be used alone or in combination of two or more.

[0023] The polyol vulcanizing agent is preferably used in an amount of 0.1 to 3 parts by mass relative to 100 parts by mass of the fluororubber, with a more preferred lower limit of 0.5 parts by mass and a more preferred upper limit of 2.5 parts by mass.

[0024] In the coating composition of the present disclosure, a vulcanization aid may be used to accelerate vulcanization. Examples of the vulcanization aid include alkyl and aralkyl quaternary ammonium salts, quaternary ammonium salts such as quaternary 1,8-diaza-bicyclo[5.4.0]-7-undecenium salts, tertiary amines, and quaternary phosphonium salts.

[0025] When the vulcanization aid is used, the amount used is, for example, 0 to 10 parts by mass relative to 100 parts by mass of the fluororubber. The lower limit is preferably 0.1 part by mass, more preferably 0.3 part by mass, and the upper limit is preferably 5 parts by mass.

[0026] The amino group-containing metal compound is preferably an amino group-containing metal compound containing at least one metal selected from the group consisting of Si, Al, Ti, and Zr. Preferred amino group-containing metal compounds include amino group-containing silane coupling agents, amino group-containing aluminum coupling agents, amino group-containing titanium coupling agents, and amino group-containing zirconium coupling agents. Preferred amino group-containing silane coupling agents include γ-aminopropyltriethoxysilane, N-β-aminoethyl-γ-aminopropyltrimethoxysilane, N-(trimethoxysilylpropyl)ethylenediamine, N-β-aminoethyl-γ-aminopropylmethyldimethoxysilane, γ-ureidopropyltriethoxysilane, and β-aminoethyl-β-aminoethyl-γ-aminopropyltrimethoxysilane. The amino group-containing metal compounds may be used alone or in combination of two or more.

[0027] The amino group-containing metal compound is preferably used in an amount of 0.1 to 2 parts by mass per 100 parts by mass of the fluororubber, with a more preferred lower limit of 0.5 parts by mass and a more preferred upper limit of 1.5 parts by mass.

[0028] The coating composition of the present disclosure contains 0.1 to 4.99 parts by mass of the polyol vulcanizing agent and the amino group-containing metal compound in total per 100 parts by mass of the fluororubber. When the total amount of the polyol vulcanizing agent and the amino group-containing metal compound is within the above range, a coating film that is less likely to peel off from the substrate and has small compression set can be obtained. In addition, the coating stability is excellent. The total amount of the polyol vulcanizing agent and the amino group-containing metal compound is preferably 1 part by mass or more, more preferably 2 parts by mass or more, and even more preferably 2.2 parts by mass or more, per 100 parts by mass of the fluororubber, and is preferably 4.5 parts by mass or less, more preferably 4 parts by mass or less.

[0029] The mass ratio of the polyol vulcanizing agent to the amino group-containing metal compound (polyol vulcanizing agent:amino group-containing metal compound) is preferably 1.0:0.1 to 1.0:1.2. When the mass ratio is within this range, a coating film that is less likely to peel off from the substrate and has a smaller compression set can be obtained. The above mass ratio is more preferably 1.0:0.2 to 1.0:1.0, and even more preferably 1.0:0.5 to 1.0:0.9.

[0030] The coating composition of the present disclosure contains an organic solvent. The coating composition of the present disclosure may be a solvent-based coating. The organic solvent is not particularly limited, and examples thereof include ketones such as methyl ethyl ketone (MEK), methyl isobutyl ketone (MIBK), diisobutyl ketone (DIBK), diacetone alcohol, cyclohexanone, and isophorone; esters such as butyl acetate and isopentyl acetate; ethers such as diethylene glycol dimethyl ether; hydrocarbons such as toluene and xylene; and amides such as N,N-dimethylacetamide and N-methyl-2-pyrrolidone. The coating composition of the present disclosure may contain only one of the organic solvents, or may contain two or more organic solvents. The amount of the organic solvent can be adjusted appropriately depending on the type of fluororubber to be added to the coating composition.

[0031] The coating composition of the present disclosure preferably further contains a stabilizer, which provides even better coating stability. Examples of the stabilizer include orthoester compounds such as orthoformates, orthocarbonates, cyclic orthoesters, lactone acetals, orthoformic acid trimethyl ester, orthoformic acid triethyl ester, orthoacetic acid trimethyl ester, orthoacetic acid triethyl ester, orthocarbonic acid trimethyl ester, orthocarbonic acid triethyl ester, orthocarbonic acid tetramethyl ester, and orthocarbonic acid tetraethyl ester; and organic acids such as monocarboxylic acids (formic acid, acetic acid, propionic acid, etc.) and dicarboxylic acids (oxalic acid, malonic acid, succinic acid, etc.). Of these, orthoester compounds are preferred, and orthoacetic acid ester compounds are more preferred. The coating composition of the present disclosure may use only one of the stabilizers, or may use two or more of the stabilizers.

[0032] The stabilizer is preferably used in an amount of 1 to 8 parts by mass relative to 100 parts by mass of the fluororubber, with a more preferred lower limit being 2 parts by mass and a more preferred upper limit being 6 parts by mass.

[0033] The coating composition of the present disclosure preferably further contains a surface conditioner. Examples of the surface conditioner include siloxane compounds, acrylic copolymers, methacrylic copolymers, etc. Among these, acrylic copolymers are preferred.

[0034] The surface conditioner is preferably used in an amount of 0.01 to 1 part by mass relative to 100 parts by mass of the fluororubber, with a more preferred lower limit of 0.02 part by mass and a more preferred upper limit of 0.5 part by mass.

[0035] The coating composition of the present disclosure preferably further contains an antifoaming agent. Examples of the antifoaming agent include silicon-based antifoaming agents, polymer-based antifoaming agents, etc. Among these, polymer-based antifoaming agents are preferred.

[0036] The antifoaming agent is preferably used in an amount of 0.05 to 4 parts by mass per 100 parts by mass of the fluororubber, with a more preferred lower limit of 0.1 part by mass, a more preferred upper limit of 3 parts by mass, and an even more preferred upper limit of 2 parts by mass.

[0037] The coating composition of the present disclosure preferably contains both the surface conditioner and the defoaming agent. This allows for excellent defoaming properties to be achieved even with small amounts of these components added. Furthermore, a coating film with excellent interlayer adhesion (particularly adhesion to the upper layer) can be obtained. The mass ratio of the surface conditioner to the antifoaming agent (surface conditioner / antifoaming agent) is preferably 1 / 20 to 1 / 50, and more preferably 1 / 30 to 1 / 40.

[0038] In addition to the above components, various additives such as fillers and colorants can be blended into the coating composition of the present disclosure. Examples of the filler include carbon black, white carbon, calcium carbonate, barium sulfate, talc, and calcium silicate. Examples of the colorant include inorganic pigments and composite oxide pigments.

[0039] A coating film can be formed by applying the coating composition of the present disclosure to a substrate and drying it. The coating composition of the present disclosure may be applied directly to the substrate, or may be applied via another layer such as a primer.

[0040] The coating composition can be applied by a known coating method such as brush coating, spray coating, dip coating, flow coating, dispenser coating, or screen coating.

[0041] After the coating and drying, curing may be carried out as needed. When other layers are provided, the curing may be carried out for each layer or for multiple layers at once. The curing may also be carried out simultaneously with the drying. The drying and curing conditions can be set appropriately depending on the type of coating composition of the present disclosure.

[0042] Substrates to which the coating composition of the present disclosure can be applied include substrates made of metal, concrete, plastic, stone, wood, paper, etc. Of these, substrates made of metal are preferred.

[0043] Examples of the metal include iron, stainless steel, aluminum, copper, brass, titanium, and plated steel plates such as zinc-plated and aluminum-plated steel plates, with stainless steel being particularly preferred.

[0044] The present disclosure also relates to a coated article comprising a metal plate and a coating film formed from the above-described fluororubber coating composition of the present disclosure provided on one or both sides of the metal plate. The coated article of the present disclosure has a coating film formed from the coating composition of the present disclosure, and therefore the coating film is less likely to peel off from the substrate (the coating film is less likely to wear out) and has a small compression set, so when the coated article is used as a sealant, excellent sealing properties can be obtained.

[0045] As the metal plate, a plate made of any of the metals exemplified as substrates to which the coating composition of the present disclosure can be applied can be used.

[0046] The coating film formed from the coating composition of the present disclosure is provided on one or both sides of the metal plate. The coating film may be provided directly on the metal plate or may be provided via another layer such as a primer layer.

[0047] The coating film preferably has a thickness of 5 to 50 μm, more preferably 10 to 30 μm.

[0048] On the coating film, other layers may be further provided.

[0049] The coated article of the present disclosure can be produced, for example, by applying the coating composition of the present disclosure to the above-mentioned metal plate and drying it. After the coating composition is applied and dried, it may be cured as needed. When other layers are provided, the curing may be carried out for each layer or for multiple layers at once. The curing may also be carried out simultaneously with the drying. The drying and curing conditions can be set appropriately depending on the type of coating composition of the present disclosure.

[0050] The coating composition and coated article of the present disclosure can be used in fields requiring coatings that are resistant to peeling from substrates and have low compression set, such as various seat belts; sealing materials such as O-rings, diaphragms, valve seals, gaskets for chemical plants, and engine gaskets; fluid transport components such as chemical-resistant tubes, fuel hoses, and joints; rolls (e.g., fuser rolls and pressure rolls) or conveyor belts for office automation equipment such as copiers, printers, and facsimiles; and are particularly suitable for use in gaskets. In one preferred embodiment, the coated article of the present disclosure is a fluororubber-coated gasket material. [Example]

[0051] The present disclosure will now be described in more detail with reference to examples, but the present disclosure is not limited to these examples.

[0052] <Preparation of Fluororubber Coating Composition> Example 1 100 parts by mass of the solid content of elastomer made of vinylidene fluoride / hexafluoropropylene copolymer (vinylidene fluoride:hexafluoropropylene = 78:22 by molar ratio) as fluororubber was mixed with 5 parts by mass of carbon black and 5 parts by mass of acid acceptor using an open roll to prepare a compound. This compound was mixed with a mixed solvent made of 240 parts by mass of diisobutyl ketone and 70 parts by mass of isophorone as an organic solvent to obtain a compound solution. Separately, 2 parts by mass of a polyol-based vulcanizing agent and 0.5 parts by mass of a vulcanization aid were dissolved in 10 parts by mass of ethanol, to which 2 parts by mass of an orthoacetic ester-based compound and 2 parts by mass of an organic acid were added as stabilizers. This solution was mixed with the previously prepared compound solution using a disper, and then 0.05 parts by mass of an acrylic copolymer as a surface conditioner, 1.8 parts by mass of a polymer-based antifoaming agent as an antifoaming agent, and 1.2 parts by mass of an amino group-containing metal compound were added to obtain a fluororubber coating composition.

[0053] Examples 2 to 6 A fluororubber coating composition was obtained in the same manner as in Example 1, except that the blending amounts of the surface conditioner and antifoaming agent (or antifoaming organic liquid) were changed as shown in Table 2. The above-mentioned defoaming organic liquid has a surface tension of 0.026 N m -1 The following isoparaffinic solvents were used:

[0054] Example 7 A fluororubber coating composition was obtained in the same manner as in Example 1, except that no orthoacetic ester compound was added as a stabilizer.

[0055] Examples 8 and 9 Fluororubber coating compositions were obtained in the same manner as in Example 1, except that the amount of the amino group-containing metal compound was changed as shown in Table 1.

[0056] Comparative Examples 1 and 2 A fluororubber coating composition was obtained in the same manner as in Example 1, except that the blending amounts of the polyol-based vulcanizing agent and the amino group-containing metal compound were changed as shown in Table 1.

[0057] Comparative Example 3 A fluororubber coating composition was obtained in the same manner as in Example 1, except that the amounts of the polyol-based vulcanizing agent and the amino group-containing metal compound were changed as shown in Table 1 and no orthoacetic acid ester-based compound was added as a stabilizer.

[0058] Comparative Example 4 A fluororubber coating composition was obtained in the same manner as in Comparative Example 1, except that no orthoacetic ester compound was added as a stabilizer.

[0059] <Preparation of coating film> 25 g of the above coating composition was placed in a fluorine-coated hand-sized tray, spread over the entire surface, and then left to stand at room temperature for 3 days. Next, it was dried at 100°C for 24 hours and then baked at 200°C for 60 minutes. After baking, the film was removed and the film thickness was measured to be approximately 300 μm.

[0060] <Preparation of painted boards (painted articles)> The coating composition was applied to a SUS301 plate that had been pre-washed with acetone using a 16-mil applicator. After pre-drying, the plate was dried at 80-100°C for 30 minutes and then baked at 200°C for 30 minutes.

[0061] <Paint film wear (missing parts)> The coated plate was clamped without spacers in a compression set measurement jig and held at 200°C for 5 hours, after which the presence or absence of chipping at the edges of the coating was visually inspected and evaluated. A rating of ◯ was given for no coating film spillage or chipping, △ for no coating film spillage but some, and × for coating film chipping. The results are shown in Table 1.

[0062] <Sealability (compression set): Complies with JIS K6262-5> The coatings were stacked to a thickness of approximately 10 mm, and the thickness was measured with a dial gauge. The sample was then placed in an oven at 175°C for 72 hours under 25% compression, then removed from the oven and allowed to cool at room temperature for 30 minutes. The thickness was then measured with a dial gauge and calculated according to the following formula. The results are shown in Table 1.

[0063] Compression set (rate) = 100 x (t0-t1) / (t0-t2) however t0: Thickness before compression (mm) t1: Thickness after compression (mm) t2: Spacer thickness (mm) Compression permanent set of 50% or less was rated as ◯, 51% to 89% as △, and 90% or more as ×.

[0064] <Defoaming property (paintability)> The fluoroelastomer coating composition was thoroughly mixed onto a SUS301 plate that had been pre-washed with acetone and then screen-printed to a thickness of 25 μm after baking. Because the first application produced many bubbles caused by air migrated from the mesh of the screen into the coating, five applications were performed. After the second and subsequent applications, a stopwatch was started immediately after each application to measure the time until the bubbles completely disappeared from the coating. The average of the four measurements was used as the defoaming time. A commercially available manual screen printer was used, with a commercially available 70-mesh ring-pattern screen. The results are shown in Table 2.

[0065] <Interlayer adhesion (to topcoat layer)> A fluororubber coating (a solution of VdF / HFP copolymer in methyl ethyl ketone (MEK)) was dip-coated onto the coating film of the coated plate obtained above as a topcoat layer, dried at 100°C for 30 minutes, and then baked at 200°C for 30 minutes to obtain a test specimen. According to JIS K5400, the coating surface of the test piece was peeled off with cellophane tape 10 times, and the number of squares of the coating remaining without peeling off (out of 100 squares) was counted. The results are shown in Table 2.

[0066] <Paint stability (pot life, coating film properties after storage)> The fluororubber coating compositions obtained in the examples and comparative examples were stored at 25°C for the times shown in Table 3, and then the coating viscosities were measured using a B-type viscometer. The fluororubber coating composition stored at 25°C for 24 hours was used to prepare coated panels in the same manner as above, and the coating film properties (coating film settling, sealing properties) were evaluated. The results are shown in Table 3.

[0067] [Table 1]

[0068] [Table 2]

[0069] [Table 3]

Claims

[Claim 1] It contains fluororubber, a polyol-based vulcanizing agent, an amino group-containing metal compound, and an organic solvent. A fluororubber coating composition comprising 0.1 to 4.99 parts by mass in total of the polyol-based vulcanizing agent and the amino group-containing metal compound per 100 parts by mass of the fluororubber.

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