JPH0381012B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to fasteners, and more particularly to fasteners such as bolts, nuts, and washers provided with an elastic fluororubber coating. Fasteners such as bolts, nuts, and washers are basic parts used in a wide range of fields, so products that meet various requirements depending on the application are desired. For example, particularly corrosion-resistant fasteners are required in chemical plants and offshore or subsea structures. In addition, high-speed workability is required for high structures and offshore structures. In order to impart corrosion resistance to fasteners, it has been proposed to coat their surfaces with fluorine resin (Japanese Unexamined Patent Publication No. 15872/1983). When coated with fluororesin, sufficient corrosion resistance can be obtained, but due to the excellent lubricity of the fluororesin surface, it is difficult to adjust the tightening torque. It has the disadvantage that it is easily damaged, and is also susceptible to scratches due to sand damage and impact during work, and scratches promote corrosion. In view of this situation, the inventors of the present invention conducted repeated research to develop a fastening tool with excellent corrosion resistance and sliding properties. By providing an elastic coating layer on the surface of the fastener, it is possible to impart corrosion resistance to the fastener.
In addition, the torque required for tightening can be reduced due to its moderate non-adhesiveness and lubricity, but unlike fluorocarbon resin, the torque required for tightening can be reduced, making it easy to adjust the torque during tightening, and there is no fear of loosening after tightening. The present invention was completed based on the discovery that the abrasion resistance provides resistance to the sand damage and scratches mentioned above. That is, the gist of the present invention resides in a fastener characterized by providing an elastic coating layer formed by applying and curing a fluorocarbon paint containing fluorocarbon rubber, fluorocarbon resin, a coupling agent, and water. . In the present invention, the term "fastener" is used to broadly include parts used for fastening structural base materials, such as bolts, nuts, and washers. In the present invention, the coating layer can be provided on the entire fastener, or in the case of bolts and nuts, it may be provided only on the threaded portion, or conversely only on the parts other than the threaded portion. In the present invention, the fluororubber coating film obtained by blending a specific amount of fluororesin imparts excellent non-adhesive properties to the surface of the fastener without substantially impairing its adhesion to the base material and mechanical properties. This is possible because the fluororesin, which itself has non-adhesive properties, unexpectedly gathers on the surface of the fluorocarbon rubber coating, allowing it to adhere to the surface of the fluorocarbon rubber without adversely affecting its adhesion to the substrate or the mechanical properties of the coating. It is believed that the above-mentioned performance of the base resin is effectively exhibited on the surface of the fluororubber coating film. According to our research, when we measure the fluorine content on the surface of a 50μ thick coating film cured at 300℃ for 30 minutes and on the adhesive surface with the substrate using fluorescent X-ray analysis, we find that It has been confirmed that the former shows about 1.5 times the amount, and the higher the curing temperature, the more the ratio of the former to the latter tends to increase. The fluororubber contained in the fluororubber paint used in the present invention is a highly fluorinated elastic copolymer, and a particularly preferred fluororubber is usually 40 to 85 mol% of vinylidene fluoride. Examples include elastomeric copolymers of Ride and at least one other fluorine-containing ethylenically unsaturated monomer that can be copolymerized therewith. Further, as the fluororubber, fluororubber containing iodine in the polymer chain can also be preferably used. This iodine-containing fluororubber has, for example, 0.001 to 10% by weight, preferably 0.001 to 5% by weight of iodine bonded to the end of the polymer chain, and copolymerized with the same 40 to 85 mol% of vinylidene fluoride as described above. It is a fluororubber whose main composition is an elastic copolymer consisting of at least one other fluorine-containing ethylenically unsaturated monomer (see JP-A-52-40543). Other fluorine-containing ethylenically unsaturated monomers that can be copolymerized with vinylidene fluoride to give elastic copolymers include hexafluoropropylene, pentafluoropropylene, trifluoroethylene, trifluorochloroethylene, and tetrafluoroethylene. Representative examples include ethylene, vinyl fluoride, perfluoro(methyl vinyl ether), perfluoro(ethyl vinyl ether), and perfluoro(propyl vinyl ether). Particularly desirable fluororubbers are vinylidene fluoride/hexafluoropropylene dielastic copolymers and vinylidene fluoride/tetrafluoroethylene/hexafluoropropylene terelastic copolymers. The fluororesins contained in the fluororubber paint used in the present invention include polytetrafluoroethylene, tetrafluoroethylene, and at least one other ethylenically unsaturated monomer copolymerizable with the same (e.g., ethylene, propylene). Olefins such as
Copolymers with halogenated olefins such as hexafluoropropylene, vinylidene fluoride, chlorotrifluoroethylene, vinylifluoride, perfluoroalkyl vinyl ethers, etc.), polychlorotrifluoroethylene, polyvinylidene fluoride, etc. It will be done. In particular,
Preferred fluororesins include polytetrafluoroethylene, tetrafluoroethylene and hexafluoropropylene, perfluoromethyl vinyl ether,
It is a copolymer with at least one of perfluoroethyl vinyl ether and perfluoropropyl vinyl ether (usually contained in an amount of 40 mol% or less based on tetrafluoroethylene). In the present invention, the coupling agent refers to a compound that acts on the interface between an organic material and an inorganic material and forms a strong bridge between the two materials through chemical or physical bonding, and is typically silicon, titanium, zirconium, hafnium, It is a compound of thorium, tin, aluminum, or magnesium, and has a group capable of bonding an organic material and an inorganic material. Among these coupling agents, preferred are silane coupling agents and orthoacid esters of Group transition elements of the periodic table (such as titanium or zirconium) and derivatives thereof, with aminosilane compounds being most preferred. Examples of the silane coupling agent include the general formula: R ¹・Si ・R ² _3-a・R ³ _a [wherein R ¹ is a chlorine atom, an amino group, an aminoalkyl group, a ureido group, a glycidoxy group, an epoxycyclohexyl group] , acryloyloxy group,
An alkyl group having 1 to 10 carbon atoms or a vinyl group having at least one functional atom or group selected from a methacryloyloxy group, a mercapto group, and a vinyl group, R ² and R ³ are each a chlorine atom, a hydroxyl group, and a carbon number 1-10 alkoxy group, carbon number 2-15
alkoxy-substituted alkoxy group, hydroxyalkyloxy group having 2 to 4 carbon atoms, and 2 to 15 carbon atoms
an atom or group selected from the acyloxy groups of a
represents 0, 1 or 2. ] Examples include silane compounds represented by the following. R ¹ is an alkyl group having a functional substituent, and preferable examples include β-aminoethyl group, γ-aminopropyl group, N-(β-aminoethyl)-γ-aminopropyl group. , γ-ureidopropyl group, γ-glycidoxypropyl group, β-
(3,4-epoxycyclohexyl)ethyl group,
Examples include γ-acryloyloxypropyl group, γ-methacryloyloxypropyl group, γ-mercaptopropyl group, β-chloroethyl group, γ-chloropropyl group, and γ-vinylpropyl group.
Further, R ¹ may be a vinyl group. Specific examples of the above-mentioned silane compounds that are preferably used include γ-aminopropyltriethoxysilane, N-β-aminoethyl-γ-aminopropyltrimethoxysilane, γ-ureidopropyltriethoxysilane, and γ-glycidoxypropyl. Trimethoxysilane, β-(3,4-epoxycyclohexyl)ethyltrimethylsilane, γ-methacryloxypropyltrimethoxysilane, γ-mercaptopropyltrimethoxysilane, γ-chloropropyltrimethoxysilane, vinyltris(β-methoxyethoxy) Silane, vinyltriethoxysilane, vinyltrichlorosilane, vinyltriacetoxysilane, N-(trimethoxysilylpropyl)ethylenediamine, N-β-aminoethyl-γ-aminopropylmethyldimethoxysilane, β-aminoethyl-β-aminoethyl −γ
-aminopropyltrimethoxysilane and the like. Among these silane coupling agents, aminosilane compounds such as γ-aminopropyltriethoxysilane (hereinafter referred to as A-1100), N-β-aminoethyl-γ-aminopropyltrimethoxysilane, N-(trimethoxysilylpropyl) Ethylenediamine, N-β-aminoethyl-γ-aminopropylmethyldimethoxysilane, γ-ureidopropyltriethoxysilane, β-aminoethyl-β-aminoethyl-γ-
Compounds such as aminopropyltrimethoxysilane not only function as vulcanizing agents for fluorocarbon rubber, but also greatly contribute to improving adhesion to substrates, and are also safe to use with liquid carriers, so they are especially useful. preferable. Examples of compounds of titanium, zirconium, hafnium and thorium include the general formula: T(OR) ₄ [wherein T represents titanium, zirconium, hafnium or thorium, and R represents an alkyl group, a cycloalkyl group or an aryl group. ] Examples include derivatives obtained by reacting an orthoacid ester represented by the following and one or more compounds having at least one functional group therewith. Examples of the above-mentioned compounds having at least one functional group include glycerin, ethylene glycol, 1,
3-butanediol, 2,3-butanediol,
Polyhydric alcohols such as hexylene glycol and octylene glycol, oxyaldehydes such as salicylaldehyde and glucose, oxyketones such as diacetone alcohol and fructose, glycolic acid, lactic acid, dioxymaleic acid,
Oxycarboxylic acids such as citric acid, diketones such as diacetylacetone, ketonic acids such as acetoacetic acid, esters of ketonic acids such as ethyl acetoacetate, oxyamines such as triethanolamine and diethanolamine, oxyphenols such as catechol and pyrogallol. Compounds etc. can be used. Examples of specific compounds when T is titanium include tetraalkyl titanate (e.g., tetraethyl titanate, tetraisopropyl titanate, tetrabutyl titanate), tetraethylene glycol titanate, triethanolamine titanate, titanium acetylacetonate. , isopropyl trioctanoyl titanate, isopropyl trimethacryl titanate, isopropyl triacryl titanate, isopropyl tri(butyl, methyl pyrophosphate) titanate, tetraisopropyl di(dilauryl phosphite) titanate,
Examples include dimethacryloxyacetate titanate, diacryloxyacetate titanate, di(dioctyl phosphate) ethylene titanate, and the like. As the zirconium compound, a compound similar to the above titanium compound can be used. Specific examples include tetraalkyl zirconates such as tetraethyl zirconate and tetrabutyl zirconate, n-propyl zirconate, isopropyl zirconate, n-butyl zirconate, isobutyl zirconate, zirconium acetylacetonate, and the like. As the hafnium and thorium compounds, compounds similar to titanium and zirconium can be used. As the tin compound, an organic or inorganic compound such as SnCl ₄ can be used. Examples of aluminum compounds include aluminum isopropylate, monosec-butoxyaluminum diisopropylate, aluminum sec-butyrate, ethyl acetoacetate aluminum diisopropylate, and aluminum tris (ethylacetoacetate). Examples of the magnesium compound include magnesium alcoholates such as magnesium methylate and magnesium ethylate. Inorganic fibrous substances as other substances contained in the fluoro rubber coating used in the present invention are used to improve the compression recovery properties of the fluoro rubber coating, and typical examples include glass fiber, carbon fiber, Examples include asbestos fibers and potassium titanate fibers. This inorganic fibrous material has an average length of at least 1μ,
The thickness is preferably 1 to 100μ. The amine compound optionally added to the fluororubber paint used in the present invention primarily functions as a vulcanizing agent for the fluororubber, and together with the coupling agent, improves mechanical properties. Examples of compounds include ethylamine, propylamine, butylamine, benzylamine,
Monoamines such as allylamine, n-amylamine, ethanolamine, ethylenediamine, trimethylenediamine, tetramethylenediamine,
Diamines such as hexamethylene diamine, 3,9-bis(3-aminopropyl)-2,4,8,10-tetraoxaspiro[5,5]undecane (hereinafter referred to as V-11), diethylenetriamine,
Examples include polyamines such as triethylenetetramine, tetraethylenepentamine, and pentaethylenehexamine, among which amine compounds having two or more terminal amino groups are preferred. To prepare the fluororubber paint used in the present invention, pigments, acid acceptors, fillers, etc. are usually blended into a mixture of fluororubber, fluororesin, and liquid carrier (if necessary, a surfactant is further added). ), a coupling agent and, if necessary, an amine compound are added to the resulting dispersion (additives such as the pigments, acid acceptors, fillers, etc. may be added as necessary), and the conventional method is carried out. By thoroughly mixing the ingredients, a uniform fluororubber paint can be obtained. The ratio of fluoro rubber and fluoro resin is 95:5 by weight.
It is desirable that the ratio is ~35:65. If the ratio of fluororesin is less than the above lower limit, the desired improvement in non-adhesiveness and lubricity will not be achieved sufficiently; on the other hand, if it is greater than the above upper limit, the desired thickness will not be achieved. A coating film of
Cracks and pinholes are likely to occur in the paint film. The amount of coupling agent added is usually fluoro rubber.
1 to 50 parts by weight per 100 parts by weight, preferably 1 to 50 parts by weight
It is 20 parts by weight. When an amine compound is added as desired, it is blended so that the total sum of the coupling agent and the amine compound takes the above value. in this case,
The molar ratio of the coupling agent to the amine compound is selected from the range of 1:99 to 99:1. As the acid acceptor, those commonly used in the vulcanization of fluororubber can be similarly used, such as one or more divalent metal oxides or hydroxides. Specific examples include oxides or hydroxides of magnesium, calcium, zinc, lead, and the like. Further, as the filler, silica, clay, diatomaceous earth, talc, carbon, etc. are used. The fluororubber paint used in the present invention is applied or impregnated onto the fastener base material by a conventional paint coating method, and cured for an appropriate period of time at a temperature of room temperature to 400°C, preferably 100 to 400°C. The desired fluororubber coating film can be obtained by this method. In the present invention, the film thickness of the fluoro rubber paint is 5 μm.
It is preferable that it is above. If the film thickness is less than 5 μm, there is a risk that unevenness will occur over the entire surface of the base material and that some areas will not be coated. The fluororubber coating film of the present invention thus obtained has properties inherent to fluororubber, such as heat resistance, weather resistance, abrasion resistance, oil resistance,
It has solvent resistance and chemical resistance, as well as excellent adhesion to substrates and its own mechanical properties, and further imparts non-adhesion and lubricity to its surface. Therefore, the fastener of the present invention has sufficient corrosion resistance, a low enough friction coefficient to satisfy high-speed workability, and an appropriate coefficient of friction to prevent loosening after tightening. Furthermore, because of its abrasion resistance, it is resistant to sand damage and scratches. Next, examples and comparative examples will be shown to specifically explain the present invention. Example 1 and Comparative Examples 1 to 3 The following liquid A and the following liquid B were uniformly mixed in a ratio of 100 parts of liquid A and 5 parts of liquid B, and then purified separately using a 200-mesh wire mesh to obtain a fluoro rubber water-based paint. Prepared. Liquid A fluoro rubber ¹⁾ Aqueous dispersion 166 parts (Fluoro rubber content 60% by weight, including nonionic HS-208) Fluoroplastic ²⁾ Aqueous dispersion 150 parts (Fluorocarbon resin content 50 weight) %, including Nonion HS-208) Magnesium oxide 3 parts Medium thermal carbon 20 parts Nonion HS-210 2 parts Water 50 parts B liquid A-1100 40 parts V-11 20 parts Water 40 parts Note 1 Vinylidene fluoride/tetra Fluoroethylene/hexafluoropropylene elastomeric copolymer. (Molar ratio 64.5:18:17.5) Note 2 Tetrafluoroethylene/hexafluoropropylene copolymer. On the other hand, an aluminum plate having a length of 100 mm, a width of 50 mm, and a thickness of 1 mm was degreased by washing with acetone. The above paint was spray-painted on the degreased aluminum plate surface, and then dried at 50 to 70°C for 10 minutes.
A coating film with a thickness of 30μ was formed, and the coating film was cured at 300°C for 10 minutes. The friction coefficient of the surface of the resulting coating film was measured using a Bauden-Leben type friction coefficient measuring device under the following conditions. Indenter shape and material: Steel ball Travel speed: 0.24cm/sec Load: 250g For comparison, Polyflon Enamel EK-1900 (primer manufactured by Daikin Industries, Ltd.) was sprayed as a fluoroplastic paint onto an aluminum plate of the same shape at a pressure.
After applying at 2.0Kg/ ^cm2 and drying at 80℃ for 15 minutes,
ES-5109 (top coat manufactured by Daikin Industries, Ltd.) was applied at a spray pressure of 2.0 kg/cm ² , dried at 80°C for 10 minutes, and then baked at 380°C for 15 minutes to form a coating film with a thickness of approximately 28μ. A test piece was created (Comparative Example 1).
In addition, Toughcoat Enamel TC-7193 (manufactured by Daikin Industries, Ltd.) was applied as a modified fluoroplastic paint to the same base material at a spray pressure of 2.0 kg/ ^cm2 , and
After drying for a minute, it is baked at 280℃ for 30 minutes to a thickness of approx.
A test piece with a coating film of 28 μm was prepared (Comparative Example 2). The coefficient of friction was similarly measured for these two types of test pieces and the unpainted iron plate. The results are shown in Table 1.

[Table] Example 2 and Comparative Examples 4 to 5 The fluoro rubber paint prepared in Example 1 and the fluoro resin paint used in Comparative Examples 1 and 2 were applied to an iron plate (SS-41, 2.5 cm 2.5cm) and cured to form a coating film approximately 28μ thick. Apply Tosa Emery #100 to this coating film at an air pressure of 1.5
Kg/cm ² was sprayed from a distance of 15 cm, and the time to start exposing the base and the time to complete peeling of the coating was measured. The results are shown in Table 2.

[Table] Comparative Example 6 A paint was prepared in the same manner as in Example 1, except for using the following liquid A' and liquid B' below, which contain the same fluororubber and fluororesin as used in Example 1.
A coating film was formed by spray painting on the surface of an aluminum plate, drying, and curing. A' liquid fluororubber solution 166 parts (Solvent: methyl ethyl ketone/methyl isobutyl ketone equivalent mixture. Fluororubber content 60% by weight) Fluoroplastic organic solvent dispersion 150 parts (solvent: methyl ethyl ketone/methyl isobutyl ketone equivalent) Mixture. Fluororesin content: 30% by weight) Magnesium oxide 3 parts Medium thermal carbon 20 parts B'liquid A-1100 40 parts V-11 20 parts Ethanol 40 parts The coating film formed in Comparative Example 6 and Example 1 When the fluorine content ratio between the surface layer and the lower layer in the coating film formed in Comparative Example 6 was calculated from the results of fluorescent X-ray analysis, it was 1.0 in Example 1.
It was 1.5. In Comparative Example 6, the fluororesin/
While the fluorine rubber composition ratio and the fluorine resin/fluorine rubber composition ratio in the lower layer are equal, in Example 1, the fluorine content in the molecule (including vinylidene fluoride, which is a hydrogen-containing monomer) is This shows that the proportion of fluororesin, which is higher than that of base rubber, is greater in the surface layer than in the lower layer.

Claims (1)

[Scope of Claims] 1. A fastening device characterized by being provided with an elastic coating layer formed by applying and curing a fluororubber paint containing fluororubber, fluororesin, a coupling agent, and water. 2 The weight ratio of fluorocarbon rubber and fluorocarbon resin is 95:5 or more
35:65. 3. The fastening tool according to claim 1, wherein the coupling agent is blended in a ratio of 1 to 50 parts by weight based on 100 parts by weight of fluororubber. 4. The fastener according to any one of claims 1 to 3, wherein the fluororubber paint further contains an amine compound. 5. The fastener according to claim 4, wherein the amine compound has at least one terminal amino group directly connected to an aliphatic hydrocarbon group. 6. The fastener according to claim 5, wherein the amine compound has at least two terminal amino groups. 7. The fastener according to any one of claims 1 to 6, wherein the fluororubber paint further contains an inorganic fibrous substance.