JPS6220240B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a metal screw element, and particularly to a metal screw element with excellent corrosion resistance. Threaded elements as fasteners, i.e. bolts
Nuts, screws, screws, etc. are jigs that are widely used in everything from daily necessities to industrial equipment, transportation equipment, buildings, etc., and play an important role as fasteners for each equipment, structure, etc. be. Among them, metal screw elements are used the most because of their high strength and are used in important parts that are subject to stress. Metal screw elements have a long track record of high quality, high performance, low cost, and a wide variety of products. When exposed to these conditions, the metal of the material corrodes, causing "rust" that makes it impossible to attach and remove the screw element, and even causes serious defects such as the screw element itself breaking or falling off. In order to suppress such corrosion of threaded elements, various treatments such as those described below have been conventionally performed. In the case of screw elements based on ordinary steel materials, for example, oxide coating treatment, plating with base metals or precious metals, two or more layers of metal plating, chemical treatment with liquid containing metal salts or heavy metal acids, oil coating,
These include coating with thermoplastic resin, coating with thermosetting resin, etc. Of the above, the oxide film treatment cannot essentially provide a long-term corrosion-resistant film, and is generally used by applying it to the surface of oil, grease, etc. Depending on the metal being plated, metal plating has a beautiful appearance and long-term corrosion resistance, but since the plating film is hard, it can crack due to stress, thermal cycles, etc., reducing its corrosion resistance. There is. Furthermore, depending on the fastening location, the corrosion rate may be greatly accelerated due to the partial battery action (galvanic corrosion action) of the metal fastened to the screw element or of the metals fastened together. The same applies to chemical treatments. Zinc chromate treatment, which is most commonly used for metal plating screw elements, is a coating made of chromic acid/dichromate hydrate, etc. applied to the zinc plating, and is used in many fields. However, these chromate coatings are also prone to cracking and deterioration, and are easily destroyed when stress is applied or when exposed to temperatures of 60 to 80 degrees Celsius or higher, greatly reducing their corrosion resistance. It has the following drawbacks. In addition, in the case of resin coating, in order to obtain a coating that exhibits the necessary corrosion resistance, the thickness of the coating must be increased, which reduces the accuracy of the shape of the screw element, so it is necessary to increase the accuracy of the tightening process. There were problems such as difficulties. The present inventors have completed the present invention as a result of intensive studies to solve the above problems. That is, the present invention relates to a metal screw element characterized by having a coating of a reaction product of a silicon compound having an aminoalkyl group and an alkoxy group and a compound having an oxirane ring. The film made of the reaction product used in the present invention is a thin film, and has the great advantage of exhibiting excellent corrosion resistance without requiring any special film-forming treatment.In particular, it prevents deterioration of corrosion resistance due to deterioration or destruction of the chromate film. It has the excellent feature of making a large contribution to the The features of the screw element of the present invention are listed below. (1) It is a screw element with excellent corrosion resistance, so it can be applied to areas exposed to highly corrosive environments. (2) Since the film is transparent, it can maintain the aesthetic appearance and optical properties of metal or metal-plated surfaces. (3) Since the coating is a thin film, it does not reduce the shape accuracy of the screw element and does not cause fastening defects during fastening. (4) Since there is no decrease in corrosion resistance due to heating or stress, it can be applied to areas of high heat and high tension.
Furthermore, heat processing and the like can be performed without sacrificing corrosion resistance. To explain the present invention in detail below, the metal screw elements applicable to the present invention include metal materials such as iron, stainless steel, aluminum, copper, brass, and plated metal, and iron with a plating coating of chromium, nickel, zinc, etc. Thread elements made of metal materials that have been treated with phosphate, Unichrome liquid treatment, alkali boiling treatment, etc. In particular, those that have been subjected to chromate treatment to maximize the effects of the present invention. It is a screw element made of metal. In addition, the threaded element refers to a bolt, as described above.
It is a fastener with a screw threaded thereon, typified by a nut, screw, screw, etc., and also includes a threaded part of an instrument device having a threaded part. Specific examples of silicon compounds having an aminoalkyl group and an alkoxy group used in the present invention include:
For example, aminomethyltriethoxysilane, γ-
Aminoalkyltrialkoxysilane having one aminoalkyl group and three alkoxy groups such as aminopropyltriethoxysilane, γ-aminoisobutyltrimethoxysilane; N-(β-aminoethyl)aminomethyltrimethoxysilane;
N having an N-(aminoalkyl)aminoalkyl group and three alkoxy groups, such as N-(β-aminoethyl)aminomethyltriethoxysilane and N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane. -(Aminoalkyl)aminoalkyltrialkoxysilane; Aminoalkylalkyldialkoxysilane having an aminoalkyl group and two alkoxy groups such as aminomethylmethyldiethoxysilane and γ-aminopropylmethyldiethoxysilane; N-(β -aminoethyl)-γ
-N-(aminoalkyl) having an N-(aminoalkyl)aminoalkyl group and two alkoxy groups, such as aminopropylmethyldimethoxysilane
These include aminoalkylalkyldialkoxysilanes, and those having two or more alkoxy groups are preferred for the present invention in order to improve rust prevention properties. Specific examples of the compound having an oxirane ring, which is another component used in the present invention, include generally known epoxy resins, namely bisphenol A and F type epoxy resins. X:

[Formula] or

[Formula] or H Y: alkyl group or H glycidylamine type epoxy resin, for example, X ₂ N-R ¹ -NX ₂ ,

【formula】 X:

[Formula] R ¹ , R ² : Alkylene group, aralkylene group, cycloalkylene group, etc. Novolak type epoxy resin, e.g. X:

[Formula] R: An alkyl group, an aralkyl group, etc. can be applied. Moreover, compounds having an oxirane ring other than the above-mentioned epoxy resins can also be used. Compounds having an oxirane ring other than epoxy resins include organosilicon compounds having an oxirane ring and an alkoxy group. Examples of such compounds include glycidoxyalkyltrialkoxysilanes such as γ-glycidoxypropyltrimethoxysilane, and glycidoxyalkylalkyldialkoxysilanes such as γ-glycidoxypropylmethyldimethoxysilane. Preferable compounds for use in the present invention are organosilicon compounds having an oxirane ring and an alkoxy group, particularly those having two or more alkoxy groups. In the present invention, the reaction ratio of the silicon compound and the compound having an oxirane ring is preferably 0.05 to 1 molar ratio of the compound having an oxirane ring to 1 part of the silicon compound based on the average molecular weight.
More preferably, the amount of the compound having an oxirane ring is 0.2 to 0.9 per 1 of the silicon compound. Compounds having an oxirane ring per mole of silicon compounds
When the amount is less than 0.05 mol, the coating composition is stable, but the effective reaction between the oxirane ring and the amino group does not substantially occur, the solution viscosity is too low when applied to the threaded element, and the film forming ability is impaired. Due to low corrosion resistance, it is difficult to obtain coating properties and thickness that should exhibit good rust prevention properties. Furthermore, if the amount of the compound having an oxirane ring exceeds 1 mol, the coating composition will not be stable and will tend to thicken or gel, and the reaction product film obtained by coating will have poor toughness. The rust prevention properties become poor due to the lack of corrosion resistance and the fact that the coating is easily damaged by external forces. The effects of the present invention are such that good results can be obtained only with the above-mentioned silicon compounds and compounds having an oxirane ring, but they must have appropriate coating properties and stability to be applied to threaded elements and reacted. Therefore, it is preferable to use a coating composition diluted with a solvent. A wide range of non-polar and polar solvents can be used, such as benzene, toluene, xylene, cyclohexane, acetone, methyl ethyl ketone, methanol, ethanol, isopropanol, ethyl ether, cellosolve, methyl cellosolve, etc. They can be appropriately selected from among them and used alone or in combination. When a solvent is used, the total concentration of the above two components in the coating composition is preferably 1 to 30% by weight. Furthermore, in the present invention, it is also possible to add other components to the coating composition containing the above two components,
For example, amine-based or phosphate-based rust preventives may be used as long as they do not cause gelling or thickening, or a trace amount of water may be added to increase the molecular weight of the reaction product film through siloxane bonding. It is possible to add, etc. When the coating composition used in the present invention is applied to a metal screw element, a film of reaction products is formed due to reactions between oxirane rings and amino groups, and siloxane bonding due to dealcoholization of an alkoxy group-containing organosilicon compound. Since a good film is formed by slight heating or moisture absorption of the paint film, the effects of the present invention can be produced without the need for a process such as heating the metal screw element to a particularly high temperature. Is possible. As described above, the present invention has a major advantage in that it improves the drawbacks of screw elements coated with chromate and exhibits excellent rust prevention performance. That is, chromate coatings are usually widely used as protective plating for most metal materials such as zinc, cadmium, aluminum, copper, etc., and exhibit effective corrosion resistance as well as aesthetic appearance, but as mentioned above, their biggest drawback is When heated, its corrosion resistance decreases significantly. For example, when heated at a temperature of 80°C or higher,
It has been confirmed through numerous experiments that the corrosion resistance obtained with 2371) is virtually the same as without a chromate coating. Reasons for this include the occurrence of cracks due to dehydration of the chromate film due to heating, and the change of soluble chromium to insoluble, and so far, no effective rust prevention treatment has been developed for such cases. Ta.
There are many demands for applying chromate-treated screw elements to heated parts or heat-processing them to create new products, and many efforts have been made to overcome the above-mentioned problems in such cases. Even when the coating according to the present invention is applied to a screw element with a chromate coating that has no thermal history and heated, and when applied to a screw element with a chromate coating that has been destroyed by heating,
It is surprising that the presence of the coating according to the present invention can exhibit rust prevention that is equivalent to or better than that before heating, and is a major feature of the present invention. According to the present invention, the rust prevention properties of screw elements made of copper, copper alloys, various chromate plated metal base materials, etc. can be greatly improved, and the screw elements of the present invention take into account heat deterioration of corrosion resistance performance. The present invention greatly contributes to the industrial world in that it can be applied to various parts without having to do so. Furthermore, the effects of the present invention are more characteristically expressed in a screw element that has a protective coating made of chromate plating and a locking element made of thermoplastic resin. In other words, screw elements with a thermoplastic resin locking feature have excellent locking performance, repeated use, sealability, and workability, but the heating required to weld the thermoplastic resin Usually, the chromate coating was severely damaged by the oxidation process, and its corrosion resistance was poor. Even if a thermoplastic resin is welded by heating to the screw element of the present invention, which is coated with a chromate coat and also has a coat according to the present invention,
The screw element of the present invention, in which a primer is applied on top of the chromate film, a thermoplastic resin is welded by heating, and the coated film according to the present invention is further formed has excellent contact resistance, and is a chromate film that does not require heating. It is surprising that the corrosion resistance is equal to or higher than that of a screw element with a coating, and the present invention is useful in the automobile industry and other industries by improving the corrosion resistance of a locking screw element using a thermoplastic resin. This will make an even greater contribution to various industries. The present invention will be explained below using Examples and Comparative Examples. Examples 1 to 2 and Comparative Examples 1 to 4 11.05 g (0.05 mol) of γ-aminopropyltriethoxysilane (molecular weight 221) as a silicon compound, and bisphenol A type epoxy resin Epicoat 1004 (Yuka Shell) as a compound having an oxirane ring. Manufactured by Epoxy, average molecular weight 1400) 14.00g
(0.01 mol) is diluted in 225.45 g of a 1/1 (weight ratio) mixed solvent of toluene and methyl ethyl ketone, and the concentration of the above components is 10% by weight (A).
It was created. Zinc chromate (yellow) bolt M, which is made of galvanized steel and further treated with yellow chromate.
-10/45 (commercial product) was coated with the coating composition (A) and air-dried for a day and night to obtain bolts of the present invention coated with a coating thickness of 2 to 5 μm (Examples 1 and 2). In addition, epoxy/phenol paint P-105 (manufactured by Toagosei Kagaku Kogyo Co., Ltd.) with a non-volatile content of 10% by weight was applied to the commercially available bolts mentioned above, and baked in an oven at 200°C for 5 minutes to obtain a film thickness of 2 to 30%. Bolts coated with resin at a thickness of 5 μm were obtained (Comparative Examples 1 and 2). Furthermore, a bolt was obtained by simply degreasing the commercially available bolt with methyl ethyl ketone (Comparative Example 3).
~4). These bolts were subjected to a salt spray test (JIS-Z-
Table 1 shows the results of investigating the occurrence of rust over a test period of 360 hours. The threaded elements of the invention clearly exhibit excellent corrosion resistance.

[Table] Examples 3 to 4 and Comparative Examples 5 to 6 N-(β-aminoethyl)- as a silicon compound
Using 0.05 mol of γ-aminopropyltrimethoxysilane and 0.015 mol of γ-glycidoxypropyltrimethoxysilane as a compound having an oxirane ring, the above component concentration was 10% by weight in a mixed solvent of toluene/methyl cellosolve = 1/1 (weight ratio). %, a coating composition (B) was prepared, and bolts similar to those in Example 1 were treated in the same manner as in Example 1 to obtain bolts of the present invention (Examples 3 and 4). In addition, vinyl chloride vinyl acetate maleic acid copolymer resin Esrec M (Sekisui Chemical Co., Ltd.)
) in 1,1,1-trichloroethane (10% by weight)
A resin-coated bolt was obtained by coating the same commercially available bolt with a solution dissolved in
6). Table 2 shows the results of a salt spray test conducted in the same manner as in Example 1.

[Table] Examples 5 to 8, Comparative Examples 7 to 10 Zinc chromate (green) bolt M with galvanized steel and further green chromate treatment
-10/45 (commercial product), zinc chromate (black) bolt M-, which was similarly treated with black chromate
10/45 (commercially available), hyperlead chromate (yellow) bolt M-10/45 similar to Example 1, nickel chrome plated bolt M-10/45 (commercially available), which is made of nickel plated steel and further chrome plated. After being treated with composition (A) in the same manner as in Example 1, heat treatment was performed at 250° C. for 15 minutes (Examples 5 to 8). In addition, the same commercially available bolts that had only been simply degreased (with methyl ethyl ketone) (Comparative Examples 7 to 10) were each heat-treated at 250°C for 15 minutes, and together with the above resin-coated bolts, they were subjected to a salt spray test (JIS-Z). -2371: Test time 240 hours) (number of repetitions: 10) The results are shown in Table 3.

【table】

[Table] Example 9 Ten zinc chromate (yellow) bolts similar to those in Example 1 were coated with epoxyphenol paint P-105 in the same manner as in Comparative Example 1, heated to 250°C, and coated with 11 nylon powder. Sanhuain powder (manufactured by Nippon Rilsan Co., Ltd.) was welded in an amount of 0.025g to 0.030g to prevent loosening. Example 1 after cooling
The composition (A) was applied and air-dried for a day and night to prepare a locking bolt of the present invention. These were subjected to a salt spray test (JIS-Z-2371) for 360 hours, but all showed almost no white rust and no red rust at all.

Claims (1)

[Claims] 1. A metal screw element characterized by having a coating of a reaction product of a silicon compound having an aminoalkyl group and an alkoxy group and a compound having an oxirane ring.