JPH0545631B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to a rust preventive composition. More specifically, the present invention relates to a rust-preventing composition having self-healing ability, which includes pressure-sensitive microcapsules encapsulating a non-volatile oil having rust-preventing ability, and a polymer having film-forming ability that is compatible with the oil. . [Prior art and its problems] Conventionally, one method of preventing rust on metal surfaces has been to apply an organic film to the metal surface to cut off contact with oxygen, water, etc. and prevent rust from forming. There is. These are called anti-rust coatings or anti-rust linings. For example, anti-rust coating is a process in which a rust-preventive paint consisting of an inorganic pigment and an organic vehicle is applied to a metal surface and then baked to form a hard coating film on the metal surface. The organic vehicle used is a thermosetting resin that can form a solvent-insoluble film by baking, such as an alkyd resin, an unsaturated polyester resin, an epoxy resin, or a modified acrylic resin. In addition, anti-rust lining can be achieved by vulcanizing rubber such as natural rubber, neoprene, or SBR, which is called a rubber lining, and lining the metal surface, or by bonding these vulcanized rubbers with an appropriate adhesive and lining the metal surface. There is something to line it with.
In addition, there are plastic linings in which plastics such as polyvinyl chloride, polyethylene, and Teflon are lined with a suitable adhesive or by baking. Furthermore, lining with asphalt is also carried out. However, the above-mentioned anti-corrosion coating or lining is no longer anti-corrosive if the coating or lining is damaged or peeled off due to mechanical impact from the outside or scratches such as scraping, and the metal surface is exposed. Rust ability is lost and rust occurs. Conventionally, when such coating or lining is damaged, the only option is to repaint or reline, which is a complicated and costly process. The reason why the above-mentioned conventional coatings or linings lose their rust-preventing ability is that once the rust-preventive coating on the metal surface has peeled off or fallen off, the coating is not regenerated. Therefore, if the paint or lining film has a so-called self-healing ability, the above-mentioned drawbacks can be overcome. [Means for Solving the Problems] An object of the present invention is to provide a rust preventive composition whose coating film has a self-healing ability, thereby overcoming the above-mentioned drawbacks of conventional coatings or linings. This is what we are trying to solve. That is, the present invention relates to a rust-preventing composition containing a pressure-sensitive microcapsule encapsulating a non-volatile oil having rust-preventing ability and a polymer having coating-forming ability that is compatible with the non-volatile oil. The invention will be further explained below. The oil encapsulated in the microcapsules of the present invention is a non-volatile oil that has anti-rust properties, has an appropriate viscosity, and can form an oil film on the metal surface, and also dissolves the polymer described below. Any oil can be used as long as it does. For example, it is appropriately selected from petroleum-based lubricating oils, synthetic oils, natural oils, and the like. In addition, the oil contained in the microcapsules is destroyed, and the contained oil flows out.
Self-healing of the coating is achieved by forming an oil film on its own and by dissolving the polymer and making it fluid again. Therefore, the above-mentioned encapsulated oil is a high-boiling oil that does not easily volatilize, and specifically, an oil with a boiling point of over 260°C is preferable. The microcapsules of the present invention are pressure-sensitive microcapsules containing the above-mentioned oil therein.
Pressure sensitive means that pressure causes the capsule to rupture, resulting in the release of the encapsulated oil.
The capsules do not break under the slightest pressure during compounding or coating, but have a film strength that is such that the polymer coating formed on the metal surface will break under pressure that exceeds the pressure that would cause it to peel or be scraped off due to impact or scratching. It is something that you have. If the particle size of the capsule is too large, uneven coating may occur, which is undesirable. Microcapsules with an average particle size of about 1μ to 500μ are usually used. The material of the capsule membrane can be arbitrarily selected depending on the capsule manufacturing method, etc., as long as it does not dissolve or swell in the encapsulated oil. For example, gelatin, polyurea,
Polyamide, polyurethane, epoxy resin, polyethylene, polystyrene, etc. are selected depending on the properties of the encapsulated oil. Further, the method for preparing microcapsules can be based on any conventionally known method. For example, microcapsules made of gelatin membrane can be prepared by core cervation. Furthermore, microcapsules made of synthetic resin films such as polyurea, polyamide, polyurethane, etc. are prepared using in situ polymerization or interfacial polymerization. In the antirust composition of the present invention, the polymer that is mixed separately with the above-mentioned microcapsules is a resin or an elastomer that dissolves in the oil contained in the capsules, and has the ability to form a coating film on the metal surface. It is something that you have. Among the above polymers, the resins include petroleum resin,
Examples include natural resins such as polystyrene, xylene resin, rosin, and polyterpene, as well as ethylene/polar monomer copolymers such as ethylene/vinyl acetate copolymer resin (EVA) or ethylene/ethyl acrylate copolymer resin (EEA). Examples include resin. Further, examples of the elastomer include natural rubber, and examples of synthetic rubber include polyisoprene rubber, polychloroprene rubber, nitrile rubber, and styrene/butadiene rubber. These resins,
Elastomers can be used alone or as a mixture of two or more. Once applied to the metal surface, the polymer consisting of the resin or elastomer forms a film that exhibits a rust-preventing effect, and the microcapsules are destroyed by the pressure of an impact or scratch, and the oil contained within them is released. When this occurs, as a result of being dissolved in the encapsulated oil, the film made of the polymer is again given fluidity and has self-healing properties, and the film is regenerated and scratches on the film are repaired. Become. In the present invention, 5 to 2000 parts by weight, preferably 10 parts by weight of encapsulated oil per 100 parts by weight of the above polymer.
Mix microcapsules equivalent to ~500 parts by weight. If the amount exceeds 2,000 parts, the coating film will not be formed completely and the encapsulated oil will drip, which is uneconomical. In order to apply the rust preventive composition of the present invention onto metal, the above-mentioned microcapsules and polymer are mixed in an appropriate solvent and applied. This solvent evaporates after being applied to the metal, but a solvent that does not dissolve or swell the membrane material of the microcapsules is used. The polymer is dissolved in the solvent or emulsified with the aid of an emulsifier, and after the composition has been applied to the metal surface, the solvent evaporates and a film is formed. Examples of solvents usually include aromatic solvents such as toluene and xylene, ester solvents such as ethyl acetate, ether solvents such as diisopropyl ether, ketone solvents such as methyl ethyl ketone and methyl isobutyl ketone, or mixed solvents thereof. General paint solvents can be used. The composition of the present invention can also be applied as an aqueous emulsion. The amount of these solvents or water can be arbitrarily selected depending on the workability during coating. Furthermore, in the composition of the present invention, conventionally known additives can be added to the oil encapsulated in the microcapsules or to the polymer within a range that achieves the effects of the present invention. For example, various rust preventive agents can be added to the encapsulated oil in order to enhance the rust prevention effect. Such rust inhibitors are usually oil-soluble polar compounds, and for example, oil-soluble sulfonates, oil-soluble carboxylates, higher fatty acids, partial esters of polyhydric alcohols, etc. can be added. In addition, fillers, organic or inorganic pigments, dyes, plasticizers, etc. conventionally known for paints may be mixed and added to the polymer constituting the composition of the present invention in arbitrary proportions separately from the microcapsules. I can do it. Further, a conventionally known rust preventive agent can be further added to further improve the rust preventive ability. The rust-preventing composition of the present invention is used for rust-preventing coating of iron, aluminum, and other metals in general. For example, if it is applied as a rust-preventing coating to the fastening parts of fastening parts such as screws, it can be applied before fastening. Not only does it have an excellent rust-preventing effect even after it has been fastened. That is, by applying the anticorrosive composition of the present invention to the fastening portion of the screw before fastening to form a polymer film on the fastening portion of the screw, the polymer film prevents rusting before fastening. Furthermore, since the coating is a dry coating, there is no stickiness on the screw surface, compared to, for example, a rust prevention method in which rust prevention oil is applied. Therefore, the screws and the like that have been rust-proofed according to the present invention are easy to handle. In addition, when screws are fastened, the screw fastened part is subjected to strong shear stress, and the rust-preventive coating on the fastened part will be damaged, but even if it is damaged, it will not be destroyed at the same time as the paint film is damaged. The oil contained in the microcapsules flows out to the outside, forming an oil film that has a rust-preventing function on its own, and also dissolves the polymer around the capsules, repairing the damage to the coating and forming a polymer film on the damaged area again. I will do it. [Effects of the present invention] By applying the rust preventive composition of the present invention to a metal surface, it is obvious that the rust preventive effect due to the polymer can be obtained at the initial stage of application, but the coating film may be damaged by mechanical impact, scratches, etc. Even if the microcapsules are destroyed, the coexisting microcapsules are destroyed by the pressure of the impact and the oil contained in them flows out, and this spilled oil forms an oil film on its own, and the polymers or resins surrounding the destroyed microcapsules. The coating is re-formed by dissolving the elastomer and giving fluidity to the coating again. This re-formed coating maintains and sustains the rust prevention effect together with the oil film. The rust-preventing composition of the present invention is used for coating the external surfaces of metals in general to prevent rust, but compared to the conventional simple application of rust-preventing oil, the composition is not sticky or hot at least at the beginning of application. But there aren't many. Therefore, even if it is applied before the screw is fastened, it is convenient because it can be handled in the same way as a screw without a coating film. Of course, if this screw causes a scratch on the coating when fastened, the coating will self-recover by the above-mentioned mechanism, and the rust prevention effect will be maintained and maintained. [Example] The present invention will be explained in detail below with reference to Examples. Example 1 (Preparation of antirust composition-1) Petroleum resin ^* 10 parts by weight Toluene 60 〃 Oil-encapsulated microcapsule ^** 30 〃 * "Nisseki Neopolymer NP-E-100" manufactured by Nippon Petrochemical Co., Ltd. (Product name) ** Encapsulated oil: diallyl alkane (boiling point 295°C) Microcapsule: polyurea microcapsule (average particle size 4μ) They were mixed in the above proportions to prepare antirust composition-1. Note that the petroleum resin was used after being dissolved in toluene. (Application of composition to steel plate and rusting test)
The above composition was applied to each sheet in an amount of 0.3 g per side, and dried at 80° C. for 15 minutes. Six coated test pieces were prepared; three were left as they were, and three had cuts (5) on the coated surface.
A square grid of mm squares (2.5 mm wide around the perimeter) was made with a knife. The cut was deep enough to reach the surface of the steel plate. Each of the six test pieces was subjected to a salt spray test according to the method specified in 6.2 of JIS Z0236, and the occurrence of rust was observed. The results are shown in Table-1. For reference, Table 1 also shows the results of a salt spray test on test pieces of the same shape that were not coated with any of the above compositions. Comparative Example 1 (Preparation of rust-preventing composition-2) Petroleum resin ^* 40 parts by weight Toluene 60 〃 * "Nisseki Neopolymer NP-E-100" (trade name) (Application of composition to steel plate and rusting Test) Six test pieces were prepared by applying the above composition and drying in the same manner as in Example 1, and three test pieces were left as they were.
The three sheets were cut in the same way as in Example 1 and subjected to a salt spray test, and the results of testing for rust occurrence are also shown in Table 1.

[Table] *The numbers in the table indicate the number of squares where rust was observed.
Example 2 The composition of Example 1 was applied to a tapping screw with a diameter of 5 mmφ.
I applied it to 10 pieces and let it dry. Average amount of application after drying is 47
mg/book. A 4 mm hole was made in a 1.6 mm thick steel plate using the applied tapping screw, and the screw was screwed into each hole until the surface of the steel plate reached the head of the screw. This product was subjected to a salt spray test according to the method specified in 6.2 of JIS Z0236 to examine the occurrence of rust. The results are shown in Table-2. As a reference example, the table below shows the rust occurrence when the same type of tapping screw without coating is screwed in in the same way.
Also listed in 2. Comparative Example 2 The composition of Example 1 was applied to 10 tapping screws of the same type and dried. The average amount applied after drying is 52mg/
It was warm with books. It was screwed into a steel plate in the same manner as in Example 2 and subjected to a salt spray test. Table 2 shows the occurrence of rust.

[Table] Shows the number of the same.
Example 3 (Preparation of rust preventive composition-3) A rust preventive oil having the following composition was prepared and microencapsulated. Rust preventive oil: Mineral oil-based lubricating oil (boiling point 320-390°C) 50 parts by weight diallyl alkane (boiling point 297°C) 40 Oil-soluble calcium sulfonate 3 Barium lanophosphate 7 Microcapsule: Polyurea resin capsule by interfacial polymerization ( Average particle size: 40μ) Rust preventive composition-3 Polystyrene resin 7.5 parts by weight The above microcapsules 22.5 Toluene 70 The above composition was prepared as the rust preventive composition-3. Note that the polystyrene resin was used after being dissolved in toluene. Using the obtained rust preventive composition-3, the rust preventive effect of the paint film and the rust preventive effect when the paint film was damaged were investigated in the same manner as in Example 1. The results are shown in Table-3. Comparative Example 3 (Preparation of antirust composition-4) The following composition was prepared. Polystyrene resin 20 parts by weight Toluene 80 With respect to this product, the rust preventive effect of the coating film and the rust preventive effect after the paint film was damaged were investigated in the same manner as in Comparative Example 1. The results are shown in Table 3 together with the results of Example 3.

[Table] * The numbers in the table indicate the number of squares where rust was observed.

Claims (1)

[Scope of Claims] 1. A rust-preventing composition comprising a pressure-sensitive microcapsule encapsulating a non-volatile oil having rust-preventing ability and a polymer having a film-forming ability that is compatible with the non-volatile oil. 2. The anticorrosive composition according to claim 1, which contains the microcapsules in an amount of 5 to 2000 parts by weight of the non-volatile oil per 100 parts by weight of the polymer.