Fluororubber paint composition and coated articles

Abstract

The present invention provides a coating composition that provides a coating film that is resistant to peeling from a substrate and has small compression set. The fluororubber coating composition comprises a fluororubber, a polyol-based vulcanizing agent, an amino group-containing metal compound, and an organic solvent, and is characterized in that 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.

Description

Technical Field

[0001] The present disclosure relates to a fluororubber paint composition and a painted article.

Background Art

[0002] Fluororubber is used not only for molded products but also for coating, taking advantage of its excellent heat resistance, oil resistance, solvent resistance, and chemical resistance. As the latter, for example, it is widely used as an industrial material by coating or impregnating various substrates such as fabrics, fibers, metals, plastics, rubbers, and others.

[0003] Patent Document 1 describes a paint containing fluororubber, a polyol-based vulcanizing agent, an amino group-containing metal compound in an amount of 15 parts by weight per 100 parts by weight of fluororubber, methyl isobutyl ketone, and the like.

[0004] Patent Document 2 describes a paint 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

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0006] An object of the present disclosure is to provide a paint composition that gives a coating film that is difficult to fall off from a substrate and has a small compression set, and a painted article provided with such a coating film.

Means for Solving the Problems

[0007] This disclosure includes fluororubber, polyol-based vulcanizing agents, amino group-containing metal compounds, and organic solvents. This invention relates to a fluororubber coating composition characterized by containing a total of 0.1 to 4.99 parts by mass of the polyol-based vulcanizing agent and the amino group-containing metal compound per 100 parts by mass of the above-mentioned fluororubber.

[0008] It is preferable that the mass ratio of the polyol-based vulcanizing agent to the amino group-containing metal compound is 1.0:0.1 to 1.0:1.2.

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

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

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

[0012] The above-mentioned stabilizer is preferably an orthoester compound.

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

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

[0015] This disclosure relates to a metal plate and A coating film formed from the fluororubber coating composition is provided on one or both sides of the above metal plate. The present invention also relates to painted articles characterized by having [a certain feature].

[0016] The above-mentioned painted 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 gives a coating film that is difficult to fall off from a substrate and has a small compression set, and a coated article provided with such a coating film.

Mode for Carrying Out the Invention

[0018] Hereinafter, the present disclosure will be specifically described. The present disclosure relates to a fluororubber coating composition containing a fluororubber, a polyol-based vulcanizing agent, an amino group-containing metal compound, and an organic solvent, and containing a total of 0.1 to 4.99 parts by mass of the polyol-based vulcanizing agent and the amino group-containing metal compound with respect to 100 parts by mass of the fluororubber. Since the fluororubber coating composition of the present disclosure contains the above components, it is difficult to fall off from the substrate (the coating film is difficult to sag), and a coating film with a small compression set can be provided. Therefore, when the above coating composition is applied to a sealing material, excellent sealing performance can be obtained. The coating composition of the present disclosure is also excellent in coating stability.

[0019] Examples of the fluororubber include vinylidene fluoride [VdF]-based fluororubbers, tetrafluoroethylene [TFE] / propylene [Pr]-based fluororubbers, TFE / Pr / VdF-based fluororubbers, ethylene [Et] / hexafluoropropylene [HFP]-based fluororubbers, Et / HFP / VdF-based fluororubbers, Et / HFP / TFE-based fluororubbers, fluorosilicone-based fluororubbers, fluorophosphazene-based fluororubbers, and the like. Among them, VdF-based fluororubbers are preferred. One or more of the above fluororubbers can be used.

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

[0021] As the above polyol-based vulcanizing agent, vulcanizing agents commonly used in polyol-vulcanized fluororubbers can be used. Examples of the above polyol-based vulcanizing agent include compounds having at least two hydroxyl groups, particularly phenolic hydroxyl groups, in the molecule and having vulcanization performance, and this compound may be a high molecular compound

[0022] Among them, as the above polyol-based vulcanizing agent, phenolic derivatives such as bisphenol A, bisphenol AF, hydroquinone and their salts; polyhydroxy compounds having two or more enol-type hydroxyl groups in the molecule such as phenolic resins and their salts; formula: R f 1 (CH2OH)2(R f 1 represents a perfluoroalkyl polyether group.) and the like are preferred. In addition to the above, any commercially available polyol-based vulcanizing agents for fluororubbers can be used as the above polyol-based vulcanizing agent. One or more of the above polyol-based vulcanizing agents can be used.

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

[0024] In the coating compositions of this disclosure, vulcanization aids may be used to promote vulcanization. Examples of such vulcanization aids include alkyl and aralkyl quaternary ammonium salts; quaternary ammonium salts such as quaternary 1,8-diaza-bicyclo[5.4.0]-7-undecenium salt; tertiary amines; and quaternary phosphonium salts.

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

[0026] The above 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 above amino group-containing metal compound may be used individually or in combination of two or more types.

[0027] The above 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 above fluororubber. A more preferable lower limit is 0.5 parts by mass, and a more preferable upper limit is 1.5 parts by mass.

[0028] The paint composition disclosed herein contains a total of 0.1 to 4.99 parts by mass of the polyol-based vulcanizing agent and the amino group-containing metal compound per 100 parts by mass of the fluororubber. Because the total amount of the polyol-based vulcanizing agent and the amino group-containing metal compound is within this range, a coating film that is less likely to peel off the substrate and has low compression set is obtained. Furthermore, it exhibits excellent paint stability. The total amount of the polyol-based 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. Furthermore, it is preferably 4.5 parts by mass or less, and more preferably 4 parts by mass or less.

[0029] The mass ratio of the polyol-based vulcanizing agent to the amino group-containing metal compound (polyol-based vulcanizing agent:amino group-containing metal compound) is preferably 1.0:0.1 to 1.0:1.2. When the mass ratio is within the above range, a coating film is obtained that is less likely to peel off from the substrate and has a smaller compression set. 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 paint compositions disclosed herein contain organic solvents. The paint compositions disclosed herein may be solvent-based paints. The above-mentioned organic solvent is not particularly limited, and for example, ketones such as methyl ethyl ketone [MEK], methyl isobutyl ketone [MIBK], diisobutyl ketone [DIBK], diacetone alcohol, cyclohexanone, and isophorone can be used, 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 can be used. The paint composition of this disclosure may use only one of the above-mentioned organic solvents, or it may use two or more of the above-mentioned organic solvents. The amount of the above-mentioned organic solvent can be appropriately adjusted depending on the type of fluororubber incorporated into the paint composition.

[0031] The paint composition of this disclosure preferably further contains a stabilizer. This results in even greater paint stability. Examples of the above-mentioned stabilizers include orthoester compounds such as orthoformate esters, orthocarbonates, cyclic orthoesters, lactone acetals, orthoformate trimethyl ester, orthoformate triethyl ester, orthoacetate trimethyl ester, orthoacetate triethyl ester, orthocarbonate trimethyl ester, orthocarbonate triethyl ester, orthocarbonate tetramethyl ester, and orthocarbonate 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.). Among these, orthoester compounds are preferred, and orthoacetate compounds are more preferred. The paint composition of this disclosure may use only one of the above-mentioned stabilizers, or it may use two or more of the above-mentioned stabilizers.

[0032] The stabilizer is preferably used in amounts of 1 to 8 parts by mass per 100 parts by mass of the fluororubber. A more preferable lower limit is 2 parts by mass, and a more preferable upper limit is 6 parts by mass.

[0033] The coating composition of this disclosure preferably further includes a surface modifier. Examples of the surface modifiers mentioned above include siloxane compounds, acrylic copolymers, and methacrylic copolymers. Among these, acrylic copolymers are preferred.

[0034] The above surface modifier is preferably used in an amount of 0.01 to 1 part by mass per 100 parts by mass of the fluororubber. A more preferable lower limit is 0.02 parts by mass, and a more preferable upper limit is 0.5 parts by mass.

[0035] The paint composition of this disclosure preferably further contains an antifoaming agent. Examples of the above-mentioned defoaming agents include silicone-based defoaming agents and polymer-based defoaming agents. Among these, polymer-based defoaming agents are preferred.

[0036] The above-mentioned defoaming agent is preferably used in amounts of 0.05 to 4 parts by mass per 100 parts by mass of the above-mentioned fluororubber. A more preferable lower limit is 0.1 parts by mass, a more preferable upper limit is 3 parts by mass, and an even more preferable upper limit is 2 parts by mass.

[0037] The paint composition of this disclosure preferably contains both the surface modifier and the defoamer described above. This makes it possible to achieve excellent defoaming properties even with small amounts of these components added. Furthermore, it is possible to obtain a coating film with excellent interlayer adhesion (especially adhesion to the upper layer). The mass ratio (surface modifier / defoaming agent) of the above surface modifier and the above defoaming agent is preferably 1 / 20 to 1 / 50, and more preferably 1 / 30 to 1 / 40.

[0038] In addition to the above components, the paint composition of this disclosure may contain various additives, such as fillers and colorants. Examples of the above-mentioned fillers include carbon black, white carbon, calcium carbonate, barium sulfate, talc, and calcium silicate. Examples of the above-mentioned colorants include inorganic pigments and composite oxide pigments.

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

[0040] The above-mentioned coating composition can be applied by known application methods such as brush application, spray coating, dipping, flow coating, dispenser coating, and screen coating.

[0041] After the above coating and drying process, curing may be performed as needed. If other layers are to be applied, the curing may be performed for each layer individually or for multiple layers at once. Furthermore, the curing may be performed simultaneously with the drying process. The drying and curing conditions can be appropriately set depending on the type of coating composition of this disclosure.

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

[0043] Examples of the above metals include iron, stainless steel, aluminum, copper, brass, titanium, and plated steel sheets with zinc plating, aluminum plating, etc. Among these, stainless steel is preferred.

[0044] The present disclosure also relates to a painted article characterized by having a metal plate and a coating film formed from the fluororubber coating composition of the present disclosure provided on one or both sides of the metal plate. Since the painted articles of this disclosure have a coating film formed from the paint composition of this disclosure, the coating film is less likely to peel off from the substrate (the coating film is less likely to deteriorate), and the compression set is small. Therefore, when the above painted articles are applied to a sealing material, excellent sealing performance can be obtained.

[0045] As the above-mentioned metal plate, a plate made of the metal exemplified as a substrate to which the coating composition of this disclosure can be applied can be used.

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

[0047] The above coating film is preferably 5 to 50 μm thick, and more preferably 10 to 30 μm thick.

[0048] Further layers may be provided on top of the above coating.

[0049] The painted articles of this disclosure can be manufactured, for example, by applying the paint composition of this disclosure onto the metal plate and drying it. After applying and drying the above-mentioned paint composition, curing may be performed as needed. If other layers are to be applied, the curing may be performed for each layer or for multiple layers at once. Alternatively, the curing may be performed simultaneously with the drying. The drying and curing conditions can be appropriately set depending on the type of coating composition of this disclosure.

[0050] The coating compositions and coated articles of this disclosure can be used in fields where coatings that are less likely to peel off from the substrate and have low compression set are required, for example, various types of sheets and belts; sealing materials such as O-rings, diaphragms, valve seals, chemical plant gaskets, and engine gaskets; fluid transport components such as chemicals, such as chemical-resistant tubes, fuel hoses, and fittings; and rolls (e.g., fixing rolls, crimping rolls) or conveyor belts for office automation equipment such as photocopiers, printers, and facsimile machines. In particular, they can be used suitably for gaskets. One preferred embodiment is that the coated articles of this disclosure are fluororubber coated gasket materials. [Examples]

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

[0052] <Preparation of fluororubber coating composition> Example 1 A compound was prepared by kneading 100 parts by mass of solids of an elastomer made of vinylidene fluoride / hexafluoropropylene copolymer (molar ratio of vinylidene fluoride:hexafluoropropylene = 78:22) as a fluororubber with 5 parts by mass of carbon black and 5 parts by mass of an acid acceptor using an open roll. This compound was then mixed with a mixed solvent consisting of 240 parts by mass of diisobutyl ketone and 70 parts by mass of isophorone as organic solvents to obtain a compound solution. Meanwhile, 2 parts by mass of a polyol-based vulcanizing agent and 0.5 parts by mass of a vulcanizing aid were dissolved in 10 parts by mass of ethanol, and 2 parts by mass of an orthoacetic acid compound and 2 parts by mass of an organic acid were added as stabilizers. This solution was mixed with the compound solution prepared earlier using a disperser, and then 0.05 parts by mass of an acrylic copolymer as a surface modifier, 1.8 parts by mass of a polymer-based defoaming 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 2-6 A fluororubber coating composition was obtained in the same manner as in Example 1, except that the amounts of the surface modifier and the defoaming agent (or defoaming 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 an orthoacetic acid ester compound was not included as a stabilizer.

[0055] Examples 8 and 9 A fluororubber coating composition was obtained in the same manner as in Example 1, except that the amount of 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 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 the orthoacetic acid ester compound was not included as a stabilizer.

[0058] Comparative Example 4 A fluororubber coating composition was obtained in the same manner as in Comparative Example 1, except that an orthoacetic acid ester compound was not included as a stabilizer.

[0059] <Preparation of coating film> 25g of the above coating composition was placed in a fluorine-coated, pocket-sized tray, spread evenly, and 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] <Manufacturing of painted boards (painted items)> The above paint composition was applied to a SUS301 plate that had been pre-cleaned with acetone using a 16 mil applicator. After pre-drying, it was dried at 80-100°C for 30 minutes, and then baked at 200°C for 30 minutes.

[0061] <Paint film deterioration (missing)> The above-mentioned painted boards were placed in a compression set measurement jig without using spacers and held at 200°C for 5 hours. After that, the presence or absence of paint film chipping at the edges was visually observed and evaluated. ○ indicated that there was no paint film overflow or chipping at all, △ indicated that there was no paint film chipping but some overflow, and × indicated that there was paint film chipping. The results are shown in Table 1.

[0062] <Sealing properties (compression set): Complies with JIS K6262-5> The above coating films were stacked to a thickness of approximately 10 mm, and the thickness was measured with a dial gauge. Next, the sample was placed in a furnace at 175°C for 72 hours under 25% compression and pressure. After removing it from the furnace and allowing it to cool at room temperature for 30 minutes, the thickness was measured with a dial gauge and calculated according to the following formula. The results are shown in Table 1.

[0063] Compression set (rate) = 100 × (t0 - t1) / (t0 - t2) however t0: Thickness before compression (mm) t1: Thickness after compression (mm) t2: Spacer thickness (mm) We rated the compression set as follows: ○ for sets with a set set of 50% or less, △ for sets between 51% and 89%, and × for sets with a set set of 90% or more.

[0064] <Defoaming property (paintability)> The above fluororubber coating composition was thoroughly stirred and then applied to a SUS301 plate that had been pre-cleaned with acetone, using a screen printing method, so that the coating film thickness after firing would be 25 μm. Since many bubbles formed when air in the screen mesh moved into the coating film during the first application, the application was performed five times. For each of the subsequent four applications, a stopwatch was started immediately after the application was completed, and the time until the bubbles completely disappeared from the coating film was measured. The average of the four measurements was taken as the defoaming time. The screen printing machine used for application was a commercially available manual printing type, and a commercially available 70-mesh ring-shaped pattern screen was used. The results are shown in Table 2.

[0065] <Interlayer adhesion (to the topcoat layer)> On the painted board obtained above, a fluororubber paint (methyl ethyl ketone [MEK] solution of VdF / HFP copolymer) was dipped 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. In accordance with JIS K5400, the cellophane tape peeling process on the coated surface of the above test specimen was repeated 10 times, and the number of squares (out of 100 squares) where the coated film remained without peeling was determined. The results are shown in Table 2.

[0066] <Paint stability (pot life, physical properties of the paint film 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 viscosity was measured using a B-type viscometer. A fluororubber coating composition stored at 25°C for 24 hours was used to prepare a coated board in the same manner as described above, and the coating film properties (coating film degradation, sealing properties) were evaluated. The results are shown in Table 3.

[0067] [Table 1]

[0068] [Table 2]

[0069] [Table 3]

Claims

1. It contains fluororubber, polyol-based vulcanizing agent, amino group-containing metal compound, stabilizer, and organic solvent. The fluororubber comprises 100 parts by mass of the polyol-based vulcanizing agent and the amino group-containing metal compound in total, 0.1 to 4.99 parts by mass. The aforementioned stabilizer comprises an orthoester compound and an organic acid. The polyol-based vulcanizing agent includes phenol derivatives and their salts, polyhydroxy compounds having two or more enol-type hydroxyl groups in the molecule and their salts, and formula: R ｆ １ (CH ２ OH) ２ (R ｆ １ This represents a perfluoroalkyl polyether group. It is at least one compound selected from the group consisting of compounds represented by ). The amino group-containing metal compound is at least one selected from the group consisting of 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. The orthoester compound is at least one selected from the group consisting of orthoformate ester, orthocarbonate ester, cyclic orthoester, lactone acetal, orthoformate trimethyl ester, orthoformate triethyl ester, orthoacetate trimethyl ester, orthoacetate triethyl ester, orthocarbonate trimethyl ester, orthocarbonate triethyl ester, orthocarbonate tetramethyl ester, and orthocarbonate tetraethyl ester. The organic acid is at least one selected from the group consisting of formic acid, acetic acid, propionic acid, oxalic acid, malonic acid, and succinic acid. The mass ratio of the polyol-based vulcanizing agent to the amino group-containing metal compound is 1.0:0.6 to 1.0:1.

2. A fluororubber coating composition characterized by the following features.

2. The fluororubber coating composition according to claim 1, wherein the metal of the amino group-containing metal compound is at least one selected from the group consisting of Si, Al, Ti, and Zr.

3. The fluororubber coating composition according to claim 1 or 2, wherein the polyol-based vulcanizing agent is 0.1 to 3 parts by mass and the amino group-containing metal compound is 0.1 to 2 parts by mass per 100 parts by mass of the fluororubber.

4. A metal plate and A coating film formed from the fluororubber coating composition according to any one of claims 1 to 3 is provided on one or both sides of the metal plate. A painted article characterized by having the following features.

5. The painted article according to claim 4, which is a fluororubber coated gasket material.

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