JP7381938B2 - Coating compositions and coated articles - Google Patents

Description

TECHNICAL FIELD This disclosure relates to coating compositions and coated articles.

Since the surface of a rubber-coated article is covered with a rubber layer, there is a problem in that the rubber layers tend to stick to each other during the manufacturing or storage process. Therefore, in order to prevent the rubber layer from sticking, materials have been proposed in which a non-adhesive layer is provided on the rubber layer.

Patent Document 1 discloses that a non-stick treatment layer is formed on a fluororubber layer from a coating composition for non-stick treatment containing a fluororesin (solid lubricant), fluororubber, an amino group-containing silane coupling agent, and water. It is stated that the following shall be provided.

International Publication No. 2007/135956

SUMMARY OF THE INVENTION The present disclosure is directed to coating compositions that provide coatings that are non-tacky and scratch resistant, as well as coated articles comprising such coatings.

The present disclosure includes a fluororubber, a vulcanizing agent, a solid lubricant, and an organic solvent,
The solid lubricant described above relates to a coating composition characterized by containing a solid lubricant (A) and a solid lubricant (B) different from the solid lubricant (A).

The solid lubricant (A) is preferably a fluororesin.

The solid lubricant (B) is preferably at least one selected from the group consisting of graphite, molybdenum disulfide, tungsten disulfide, graphite fluoride, and boron nitride.

The mass ratio of the fluororubber to the solid lubricant (fluororubber/solid lubricant) is preferably from 20/80 to 80/20.

The mass ratio of the solid lubricant (A) and the solid lubricant (B) (solid lubricant (A)/solid lubricant (B)) is preferably from 50/50 to 90/10.

The coating composition is preferably a coating composition for non-stick treatment.

The coating composition is preferably a coating composition for non-stick treatment of elastomer layers.

The present disclosure provides a metal plate;
An elastomer layer provided on one or both sides of the metal plate,
The present invention also relates to a coated article comprising a coating formed from the coating composition of the present disclosure, provided on the elastomer layer.

The elastomer layer is preferably a fluororubber layer.

The coated article is preferably a fluororubber coated gasket material.

According to the present disclosure, it is possible to provide a coating composition that provides a coating film with excellent non-stick properties and scratch resistance, and a coated article provided with such a coating film.

The present disclosure will be specifically described below.
The present disclosure includes a fluororubber, a vulcanizing agent, a solid lubricant, and an organic solvent, and the solid lubricant includes a solid lubricant (A) and a solid lubricant (B) different from the solid lubricant (A). A coating composition comprising:
Since the coating composition of the present disclosure contains the above-mentioned components, it can provide a coating film with excellent non-stick properties and scratch resistance.
The above-mentioned non-adhesiveness includes, for example, the non-adhesiveness between coating films formed from the coating composition of the present disclosure during manufacture or storage, and the non-adhesion of coating films formed from the coating composition of the present disclosure. Examples include non-adhesion to other materials (press molds, etc.) that come into contact with the surface of the coating during manufacture or use.
The coating composition of the present disclosure also has excellent coating stability.

The above-mentioned fluororubbers 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, and the like. Among them, VdF-based fluororubber is preferred.
The above fluororubbers may be used alone or in combination of two or more.

The above-mentioned VdF-based fluororubbers include VdF/HFP copolymer, VdF/TFE/HFP copolymer, VdF/chlorotrifluoroethylene [CTFE] copolymer, VdF/CTFE/TFE copolymer, VdF/perfluoroethylene (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, VdF/a copolymer of a fluorine-containing monomer represented by formula (1), and the like.
Formula (1):
CH ₂ =CFRf (1)
(In the formula, Rf is a linear or branched fluoroalkyl group having 1 to 12 carbon atoms)

Examples of the vulcanizing agent include amine vulcanizing agents, polyol vulcanizing agents (polyhydroxy aromatic compounds, peroxide vulcanizing agents, etc.), and among these, polyol vulcanizing agents are preferred.

As the polyol vulcanizing agent, a vulcanizing agent commonly used for polyol-vulcanized fluororubbers can be used. Examples of the polyol vulcanizing agent include compounds having at least two hydroxyl groups, particularly phenolic hydroxyl groups, in the molecule and having vulcanizing performance, and this compound may be a polymer compound.

As the polyol vulcanizing agent, among others, phenol derivatives such as bisphenol A, bisphenol AF, and hydroquinone, and salts thereof; polyhydroxy compounds having two or more enol type hydroxyl groups in the molecule, such as phenol resin, and salts thereof; Compounds represented by the formula: R _f ¹ (CH ₂ OH) ₂ (R _f ¹ represents a perfluoroalkyl polyether group) are preferred.
As the polyol vulcanizing agent, in addition to the above, any commercially available polyol vulcanizing agent for fluororubber can be used.
One type or two or more types of the above polyol vulcanizing agents can be used.

In the coating composition of the present disclosure, a vulcanization aid can also be used to promote vulcanization. The above-mentioned vulcanization aids 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; ; Examples include quaternary phosphonium salts.

The amount of the vulcanizing agent and the vulcanizing aid added can be appropriately selected depending on the type and amount of the fluororubber used, and is not particularly limited. Furthermore, two or more of the above-mentioned materials may be used in combination.

The coating composition of the present disclosure includes, as the solid lubricant, a solid lubricant (A) and a solid lubricant (B) different from the solid lubricant (A). By using different solid lubricants in combination in this way, a coating film that is not only non-adhesive but also has excellent scratch resistance can be obtained.

Examples of the solid lubricants (solid lubricants (A) and (B)) include fluororesin, graphite, molybdenum disulfide, tungsten disulfide, graphite fluoride, boron nitride, etc., and two or more of these can be used in combination.

The solid lubricant (A) is preferably a fluororesin.

Examples of the fluororesin include polytetrafluoroethylene [PTFE], tetrafluoroethylene [TFE]/hexafluoropropylene [HFP] copolymer [FEP], and TFE/perfluoro(alkyl vinyl ether) [PAVE] copolymer. [PFA], TFE/HFP/PAVE copolymer [EPA], polychlorotrifluoroethylene [PCTFE], TFE/chlorotrifluoroethylene [CTFE] copolymer, TFE/ethylene [Et] copolymer [ETFE] , polyvinylidene fluoride [PVDF], etc. Among them, PTFE is preferable in terms of heat resistance, abrasion resistance, etc.

The solid lubricant (B) is preferably at least one selected from the group consisting of graphite, molybdenum disulfide, tungsten disulfide, graphite fluoride, and boron nitride, and is preferably at least one selected from the group consisting of graphite and molybdenum disulfide. It is more preferable that it is at least one selected from the group consisting of graphite.

The mass ratio (A/B) of the solid lubricant (A) and the solid lubricant (B) is preferably from 50/50 to 90/10, and preferably from 55/45 to 85/15. The ratio is more preferably 60/40 to 80/20, and particularly preferably 65/45 to 80/20.

The above-mentioned solid lubricant preferably has an average particle size of 0.1 to 10 μm, with a more preferable lower limit of 0.15 μm and a more preferable upper limit of 5 μm, from the viewpoint of stably retaining the solid lubricant in the coating film.
In this specification, the average particle size is a value measured using CAPA700 (centrifugal sedimentation type particle size distribution analyzer) manufactured by Horiba, Ltd.

The mass ratio of the fluororubber to the solid lubricant (fluororubber/solid lubricant) is preferably 20/80 to 80/20, more preferably 25/75 to 75/25, and 30/80 to 80/20, more preferably 25/75 to 75/25. More preferably, the ratio is from /70 to 70/30.

The above-mentioned organic solvent is not particularly limited, and includes, for example, ketones such as methyl ethyl ketone [MEK], methyl isobutyl ketone [MIBK], diisobutyl ketone [DIBK], diacetone alcohol, cyclohexanone, isophorone, and 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 use only one kind of the above organic solvent, or may use two or more kinds of organic solvents. The amount of the organic solvent blended can be adjusted as appropriate depending on the type of fluororubber to be blended into the coating composition.

Since the coating composition of the present disclosure contains the above organic solvent, it can be used as a solvent-based coating. Therefore, unlike water-based paints that use water as a solvent, there is no need to use a surfactant as a dispersant, and it is possible to prevent the physical properties of the paint film from deteriorating due to the surfactant remaining in the paint film. . It also has superior paint stability compared to water-based paints.

The coating composition of the present disclosure may contain a stabilizer in addition to the above-mentioned fluororubber, vulcanizing agent, solid lubricant, and organic solvent. Examples of the stabilizer include orthoformate, orthocarbonate, cyclic orthoester, lactone acetal, trimethyl orthoformate, triethyl orthoformate, trimethyl orthoacetate, triethyl orthoacetate, trimethyl orthocarbonate, and triethyl orthocarbonate. , orthoesters such as orthocarbonate tetramethyl ester, orthocarbonate tetraethyl ester; organic acids such as monocarboxylic acids (formic acid, acetic acid, propionic acid, etc.), dicarboxylic acids (oxalic acid, malonic acid, succinic acid, etc.), etc. be able to. The coating composition of the present disclosure may use only one kind of the above stabilizer, or may use two or more kinds of stabilizers.

In addition to the above components, the coating composition of the present disclosure may contain various additives such as fillers, colorants, antifoaming agents, surface conditioners, and the like.
Examples of the filler include carbon black, white carbon, calcium carbonate, barium sulfate, talc, and calcium silicate. Among them, carbon black is preferred.
Examples of the coloring agent include inorganic pigments and composite oxide pigments.
Examples of the antifoaming agent include silicone antifoaming agents and polymer antifoaming agents.
Examples of the surface conditioner include siloxane compounds, acrylic copolymers, methacrylic copolymers, and the like.

A coating film can be formed by applying the coating composition of the present disclosure to an object to be coated and drying it.

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.

After the above coating and drying, curing may be performed if necessary. The above curing may be performed for each layer or for multiple layers at once. Moreover, the above-mentioned curing may be performed simultaneously with the above-mentioned drying.
Drying and curing conditions can be appropriately set depending on the coating composition of the present disclosure and the type of object to be coated.

Since the coating composition of the present disclosure provides a coating film with excellent non-stick properties and scratch resistance, it can be suitably used as a coating composition for non-stick treatments. When the object to be treated is an elastomer layer, the non-adhesive property and scratch resistance are more markedly exhibited, so it can be particularly suitably used as a coating composition for non-adhesive treatment of the elastomer layer. The elastomer layer is preferably a coating film of a coating composition containing an elastomer.

Examples of elastomers that can be used in the above elastomer layer include fluororubber, nitrile rubber, hydrogenated nitrile rubber, styrene-butadiene rubber (SBR), chloroprene rubber (CR), butadiene rubber (BR), natural rubber (NR), and isoprene rubber. (IR), ethylene-α-olefin rubber, ethylene-α-olefin-nonconjugated diene rubber, chlorinated polyolefin rubber, chlorosulfonated polyolefin rubber, acrylic rubber, ethylene-based acrylic rubber, epichlorohydrin rubber, silicone rubber, butyl rubber (IIR) , ethylene-vinyl ester rubber and ethylene-methacrylate rubber. Among them, fluororubber is preferred.

The above-mentioned fluororubbers 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, and the like. Among them, VdF-based fluororubber is preferred.
The above fluororubbers may be used alone or in combination of two or more.

The above-mentioned VdF-based fluororubbers include VdF/HFP copolymer, VdF/TFE/HFP copolymer, VdF/chlorotrifluoroethylene [CTFE] copolymer, VdF/CTFE/TFE copolymer, VdF/perfluoroethylene (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, VdF/a copolymer of a fluorine-containing monomer represented by formula (1), and the like.
Formula (1):
CH ₂ =CFRf (1)
(In the formula, Rf is a linear or branched fluoroalkyl group having 1 to 12 carbon atoms)

The present disclosure includes a metal plate, an elastomer layer provided on one or both sides of the metal plate, and a coating film formed from the coating composition of the present disclosure, provided on the elastomer layer. The present invention also relates to a coated article characterized by:
Since the coated article of the present disclosure has a coating film formed from the coating composition of the present disclosure, it has excellent non-stick properties and scratch resistance.

Examples of the metal plate include plates made of iron; stainless steel; aluminum; copper; brass; titanium; plated steel plate coated with zinc plating, aluminum plating, and the like. Among these, stainless steel plates and aluminum plates are preferred.

As the elastomer constituting the elastomer layer, the elastomers listed above for the elastomer layer that can be treated with the coating composition of the present disclosure can be used, and among them, fluororubber is preferred.

The elastomer layer is preferably a coating film of a coating composition containing the elastomer.

The thickness of the elastomer layer is preferably 5 to 50 μm, more preferably 10 to 30 μm.

The elastomer layer is provided on one or both sides of the metal plate. The elastomer layer may be provided directly on the metal plate, or may be provided via another layer such as a primer layer.

A coating film formed from the coating composition of the present disclosure is provided on the elastomer layer. The coating film may be provided directly on the elastomer layer or may be provided via another layer; Preferably, it is provided directly on the elastomer layer.

The thickness of the coating film is preferably 0.5 μm or more and less than 10 μm, more preferably 1 to 5 μm.

Although another layer may be provided on the coating film, no other layer is provided on the coating film, since the non-adhesive property and scratch resistance are more prominently exhibited. That is, it is preferable that the coating film is the outermost surface of the coated article.

The coated article of the present disclosure can be obtained, for example, by coating the coating composition containing the elastomer on the metal plate and drying the resulting coating film, and then applying the coating composition of the present disclosure on the resulting coating film and drying the coating composition. It can be manufactured by
After coating and drying the coating composition forming each layer, curing may be performed if necessary. The above curing may be performed for each layer or for multiple layers at once. Moreover, the above-mentioned curing may be performed simultaneously with the above-mentioned drying.
Drying and curing conditions can be appropriately set depending on the coating composition of the present disclosure and the type of elastomer layer.

The coating composition and coated article of the present disclosure can be used in fields where non-stick properties, scratch resistance, etc. are required, such as various seat belts; O-rings, diaphragms, valve seals, chemical Sealing materials for plant gaskets, engine gaskets, etc. Fluid transport members such as chemical liquids, such as chemical-resistant tubes, fuel hoses, and joints; Rolls for OA equipment such as copying machines, printers, and facsimiles (e.g., fixing rolls, pressure rolls) Alternatively, it can be used for conveyor belts, etc., and particularly, it can be suitably used for gaskets. It is one of the preferred embodiments that the coated article of the present disclosure is a fluororubber coated gasket material.

Next, the present disclosure will be described in more detail with reference to Examples, but the present disclosure is not limited to these Examples.

<Preparation of coating composition for non-stick treatment>
Example 1
As a fluororubber, 37.5 parts by mass of graphite, 37.5 parts by mass of graphite, 37.5 parts by mass of fluororesin (polytetrafluoropropylene), A compound was prepared by kneading 112.5 parts by mass of ethylene (PTFE) and 5 parts by mass of an acid acceptor using an open roll. This compound was mixed with 700 parts by mass of methyl ethyl ketone as an organic solvent to obtain a compound solution.
On the other hand, 2 parts by mass of a polyol-based vulcanizing agent and 0.5 parts by mass of a vulcanization aid were dissolved in a mixed solvent consisting of 200 parts by mass of methyl ethyl ketone as an organic solvent and 5 parts by mass of ethanol, and a stabilizer was dissolved therein. Then, 2 parts by mass of an orthoacetic acid ester compound and 2 parts by mass of an organic acid were added. This solution was mixed with the previously prepared compound solution using a disper to obtain a non-stick coating composition.

Examples 2 and 6
A coating composition for non-adhesive treatment was obtained in the same manner as in Example 1, except that the amounts of fluororubber, fluororesin, and graphite were changed as shown in Table 1, and carbon black was added.

Examples 3-5
A coating composition for non-stick treatment was obtained in the same manner as in Example 1, except that the blending amounts of fluororubber, fluororesin, and graphite were changed as shown in Table 1.

Examples 7 to 10
A coating composition for non-stick treatment was obtained in the same manner as in Example 1 except that the graphite was changed as shown in Table 1.

Comparative example 1
A coating composition for non-stick treatment was obtained in the same manner as in Example 1, except that the blending amounts of fluororubber, fluororesin, and graphite were changed as shown in Table 1.

Comparative example 2
100 parts by mass of an aqueous dispersion of fluororubber (vinylidene fluoride/tetrafluoroethylene/hexafluoropropylene copolymer) (fluororubber content 60% by mass), an aqueous dispersion of fluororesin (polytetrafluoroethylene [PTFE]) 100 parts by mass (fluororesin content: 60% by mass), 6 parts by mass of an amino group-containing silane coupling agent, and 3800 parts by mass of water were mixed to obtain a coating composition for non-stick treatment.

<Preparation of test piece (coated article)>
Fluororubber paint (VdF/HFP copolymer diisobutyl ketone solution) was applied using a flow coater to an aluminum plate that had been previously cleaned with acetone, dried at 100°C for 30 minutes, and then baked at 200°C for 30 minutes. A coated plate with a rubber layer thickness of 25 μm was obtained.
The coated board obtained above was coated with the non-adhesive coating composition obtained in the Examples and Comparative Examples by dip coating at room temperature, then dried at 80 to 100°C for 5 minutes, and then heated to 200°C for 5 minutes. A test piece (coated article) having a non-adhesive treated layer with a thickness of 1 μm was obtained by baking for a minute.

Each physical property was evaluated by the following method. The results are shown in Table 1.
<Non-adhesion test (non-adhesion between coating films)>
The above test piece was cut out to a width of 2 cm, and the coated film surfaces of 2 cm x 3 cm were stacked on top of each other and held under conditions of a load of 1 kg and a temperature of 200° C. for 1 hour. For the test pieces stacked under the above conditions, the tensile strength was measured at room temperature using a universal testing machine (manufactured by Shimadzu Corporation) according to the tensile shear adhesive strength test method of JIS K6850, and the tensile strength was measured according to the following criteria. The surface adhesion was evaluated.
○: Tensile strength 0MPa
△: Tensile strength less than 1.0 x 10 ^-2 MPa ×: Tensile strength 1.0 x 10 ^-2 MPa or more

<Mold contamination (non-adhesiveness between paint film and aluminum plate)>
The above test piece was cut out to a width of 2 cm, and a separately prepared aluminum plate (2 cm width) was layered on the 2 cm x 3 cm coating surface, and held under conditions of a load of 1 kg and a temperature of 200° C. for 1 hour. After peeling off the stacked test pieces, the degree of contamination of the aluminum plate was visually evaluated using the following criteria.
○: No contamination △: Slightly contaminated ×: Fully contaminated

<Scratch resistance>
Using a HEIDON tester, the scratch generation load on the coating film of the test piece was measured and evaluated based on the following criteria.
○: 80g or more △: 60-70g
×: 40-50g

<Paint stability>
The non-adhesive coating compositions obtained in Examples and Comparative Examples were stored at 25° C. for 24 hours, then redispersed, filtered through a 100-mesh wire mesh, the concentration of the filtration residue was measured, and evaluated using the following criteria.
○: Less than 1% by mass △: 2-4% by mass
×: 5% by mass or more

Claims (8)

Contains fluororubber, vulcanizing agent, solid lubricant, organic solvent and stabilizer,
The solid lubricant includes a solid lubricant (A) and a solid lubricant (B) different from the solid lubricant (A),
The vulcanizing agent is a polyol vulcanizing agent,
The stabilizer includes orthoesters and organic acids,
The solid lubricant (A) is a fluororesin,
A coating composition characterized in that the solid lubricant (B) is at least one selected from the group consisting of graphite, molybdenum disulfide, tungsten disulfide, graphite fluoride, and boron nitride. The coating composition according to claim 1 , wherein the mass ratio of the fluororubber and the solid lubricant (fluororubber/solid lubricant) is 20/80 to 80/20. 3. The solid lubricant (A) and the solid lubricant (B) have a mass ratio (solid lubricant (A)/solid lubricant (B)) of 50/50 to 90/10. paint composition. The coating composition according to any one of claims 1 to 3 , which is a coating composition for non-stick treatment. The coating composition according to any one of claims 1 to 4 , which is a coating composition for non-stick treatment of an elastomer layer. metal plate and
an elastomer layer provided on one or both sides of the metal plate;
A coated article comprising a coating film formed from the coating composition according to any one of claims 1 to 5 , provided on the elastomer layer. The coated article according to claim 6 , wherein the elastomer layer is a fluororubber layer. The coated article according to claim 6 or 7, which is a fluororubber coated gasket material.