Rust-preventive compositions and automotive parts

Abstract

This invention provides a rust-preventive composition that exhibits excellent rust prevention properties at the joints of vehicle body panels such as doors, provides sufficient corrosion resistance, and prevents liquid dripping from the vehicle body. The rust-preventive composition comprises a rust-preventive additive, a wax, bentonite, a hardened oil, and two or more diluents of different viscosities. The wax is selected from polyethylene-based or polypropylene-based synthetic waxes, or microcrystalline waxes, and has a melting point in the range of 60°C to 130°C. The rust-preventive composition contains the aforementioned rust-preventive additive in an amount ranging from 12% to 39% by mass relative to the total composition, contains the aforementioned bentonite in an amount ranging from 2% to 6% by mass relative to the total composition, and contains the aforementioned wax in an amount ranging from 3% to 13% by mass relative to the total composition.

Description

Technical Field

[0001] This invention relates to rust-preventive compositions. Furthermore, it relates to automotive parts having a rust-preventive coating formed from the rust-preventive composition. Background Technology

[0002] As a rust inhibitor used in the running parts of automobile bodies, bag structures and panel joints such as doors and hoods, wax-based rust inhibitors are currently used as compositions in which wax and various additives are dissolved or dispersed in mineral oil or other organic solvents.

[0003] For example, Patent Document 1 discloses a rust-preventive composition comprising rust-preventive additives, wax, hardening oil and diluent, and also comprising 2 to 6% by mass of bentonite relative to the composition as a whole.

[0004] In addition, Patent Document 2 discloses a rust-preventive composition which is prepared by dissolving or dispersing thermally polymerized drying oils, waxes and / or rust-preventive additives in a specific solvent.

[0005] Existing technical documents

[0006] Patent documents

[0007] Patent Document 1: Japanese Patent Application Publication No. 2014-198864;

[0008] Patent Document 2: Japanese Patent Application Publication No. 2006-16632. Summary of the Invention

[0009] The problem the invention aims to solve

[0010] These conventional rust-preventive compositions offer little improvement in rust prevention, particularly for the aforementioned panel joints. The present invention aims to provide a rust-preventive composition that provides excellent rust prevention for panel joints, exhibits sufficient corrosion resistance, and prevents liquid dripping from the vehicle body.

[0011] Solution for solving the problem

[0012] Through research, the inventors have discovered a rust-preventive composition that, by using two or more diluents of different viscosities, provides excellent rust prevention at panel joints, exhibits sufficient corrosion resistance, and prevents liquid dripping from the vehicle body. In other words, this invention comprises the following:

[0013] (1) A rust-preventive composition comprising a rust-preventive additive, a wax, bentonite, a hardening oil, and two or more diluents with different viscosities, wherein the wax is selected from polyethylene-based or polypropylene-based synthetic waxes or microcrystalline waxes and has a melting point range of 60°C or higher and 130°C or lower, wherein the rust-preventive composition comprises the aforementioned rust-preventive additive in a range of 12% by mass or higher and 39% by mass or lower relative to the total composition, comprises the aforementioned bentonite in a range of 2% by mass or higher and 6% by mass or lower relative to the total composition, and comprises the aforementioned wax in a range of 3% by mass or higher and 13% by mass or lower relative to the total composition.

[0014] (2) The rust-preventive composition according to (1) above, wherein the rust-preventive composition contains the diluent with the lowest viscosity among the two or more diluents with different viscosities, which are in the range of 40% or more and 80% or less of the total amount of diluent.

[0015] (3) The rust-preventive composition according to (1) or (2) above, wherein the kinematic viscosity of the diluent with the lowest viscosity among the two or more diluents with different viscosities is 10 mm at 40°C. 2 / s or higher and 30mm 2 Within the range of / s and below.

[0016] (4) An automotive component having a rust-preventive coating formed from any one of the rust-preventive compositions described in (1) to (3) above.

[0017] Invention Effects

[0018] The rust-preventive composition of the present invention provides excellent rust prevention for joints of vehicle body panels such as doors, exhibits sufficient corrosion resistance, and prevents liquid dripping from the vehicle body. Furthermore, it enables the provision of automotive parts having a rust-preventive coating formed by this composition. Detailed Implementation

[0019] As one embodiment of the present invention, the rust-preventive composition comprises (A) a rust-preventive additive, (B) a synthetic wax selected from polyethylene or polypropylene, or a microcrystalline wax with a melting point of 60°C or higher and 130°C or lower, (C) bentonite, (D) a hardening oil, and (E) two or more diluents with different viscosities.

[0020] <(A) Rust Inhibitor Additive>

[0021] As a rust inhibitor, it is only necessary to impart rust-preventive properties to the rust-preventive composition. Examples of suitable additives include sulfonates (alkylbenzene sulfonates, such as calcium salts), carboxylates (carboxylic acid amine salts, etc.), amine salts, fatty acid esters, oxidized paraffin salts, and oxidized wax salts. Commercially available rust inhibitors can also be used directly. Furthermore, some rust inhibitors are pre-diluted with organic solvents; those with the lowest possible volatile components are preferred. Specific examples include sulfonates, fatty acid esters, and oxidized paraffin salts found in oil fractions. A single rust inhibitor can be used, or two or more can be used in combination.

[0022] The content of the rust-preventive additive is preferably in the range of 12% by mass or more and 39% by mass or less, more preferably in the range of 16% by mass or more and 35% by mass or less, relative to the overall rust-preventive composition.

[0023] <(B) Wax>

[0024] As for the wax, there are no particular restrictions as long as it is a synthetic wax selected from polyethylene or polypropylene, or a microcrystalline wax with a melting point in the range of 60°C or higher and 130°C or lower, and preferably a melting point in the range of 80°C or higher and 120°C or lower.

[0025] As for synthetic waxes, there are no particular restrictions as long as they are polyethylene-based or polypropylene-based. Examples include Fischer-Tropsch wax, polyethylene wax, polypropylene wax, and copolymers of ethylene and propylene. Furthermore, polyethylene-based synthetic waxes refer to waxes with multiple ethylene structures, while polypropylene-based synthetic waxes refer to waxes with multiple propylene structures. A single type of wax can be used, or two or more types can be used in combination.

[0026] In addition to the microcrystalline waxes mentioned above, you can also use plant-based waxes such as candelilla wax, carnauba wax, rice bran wax, Japanese wax, and jojoba oil; animal-based waxes such as beeswax, lanolin, and whale wax; mineral-based waxes such as lignite wax, ceresin wax, and pure ceresin wax; and natural waxes such as paraffin wax, microcrystalline wax, and petroleum jelly.

[0027] The wax content, relative to the overall rust-preventive composition, is preferably in the range of 3% by mass or more and 13% by mass or less, more preferably in the range of 3% by mass or more and 10% by mass or less.

[0028] When using synthetic wax, although it also depends on the properties of the synthetic wax, it is possible to reduce the wax content in the overall rust-preventive composition, for example, to 6% by mass or less, and further to 5% by mass or less, relative to the overall rust-preventive composition.

[0029] <(C) Bentonite>

[0030] Bentonite is a mineral with montmorillonite as its main component, which has a layered structure composed of plate-like crystals made of aluminosilicates. The particle size of bentonite is preferably in the range of 0.1 μm or more and 10 μm or less, and more preferably in the range of 1 μm or more and 5 μm or less.

[0031] The bentonite content, relative to the overall rust-preventive composition, is preferably in the range of 2% by mass or more and 6% by mass or less, and more preferably in the range of 3% by mass or more and 6% by mass or less.

[0032] <(D) Hardened Oil>

[0033] Examples of hardened oils include natural drying oils such as linseed oil, perilla oil, tung oil, hemp seed oil, safflower oil, audie oil, sardine oil, herring oil, and castor oil, as well as synthetic drying oils such as dehydrated castor oil. Furthermore, the iodine value of the hardened oil is preferably 80 or higher. A single hardened oil can be used alone, or in combination with two or more other oils.

[0034] The content of the hardened oil is not particularly limited, but is preferably in the range of 8% by mass or more and 25% by mass or less relative to the overall rust-preventive composition, and more preferably in the range of 9% by mass or more and 15% by mass or less.

[0035] <(E) Diluent>

[0036] As a diluent, there are no particular limitations as long as it is a base oil diluent, and it can be, for example, mineral oil-based lubricants, synthetic lubricants, liquid saturated hydrocarbon mixtures, vegetable oil-based semi-drying oils, and vegetable oil-based non-drying oils. Specific examples include, as mineral oil-based lubricants, paraffinic lubricants and naphthenic lubricants; as synthetic lubricants, esters, polyalphaolefins, polyalkylene glycols, polybutenes, and alkyl diphenyl ethers; as liquid saturated hydrocarbon mixtures, liquid paraffin; as vegetable oil-based semi-drying oils, soybean oil, cottonseed oil, rapeseed oil, rice oil, sesame oil, sunflower oil, and corn oil; and as vegetable oil-based non-drying oils, olive oil, peanut oil, and camellia oil. In this embodiment, two or more diluents with different viscosities are used in combination.

[0037] The content of the diluent is not particularly limited, but is preferably in the range of 33% by mass or more and 60% by mass or less relative to the overall rust-preventive composition, and more preferably in the range of 40% by mass or more and 57% by mass or less.

[0038] There is no particular limitation on the combination of two or more diluents. Relative to the total amount of diluent, it is preferable to contain the diluent with the lowest viscosity among two or more diluents in the range of 40% to 80% by mass, and more preferably the diluent with the lowest viscosity among two or more diluents in the range of 50% to 78% by mass.

[0039] Furthermore, among the two or more diluents with different viscosities mentioned above, the kinematic viscosity of the diluent with the lowest viscosity is preferably 10 mm at 40°C. 2 / s or higher and 30mm 2 In the range below / s, more preferably within 15mm 2 / s or higher and 27mm 2 The range is below / s. Furthermore, the kinematic viscosity of the diluent with the highest viscosity among two or more diluents is 50 mm at 40°C. 2 A speed of 80mm or higher is acceptable, with 80mm being the preferred value. 2 / s or higher, more preferably 100mm 2 / s or more.

[0040] <Other ingredients>

[0041] The rust-preventive composition of this embodiment may also contain fillers. Examples of fillers include calcium carbonate, kaolin, talc, mica, and various other known extender pigments. The content of fillers is not particularly limited, but is preferably in the range of 5% by mass or more and 15% by mass or less relative to the total rust-preventive composition, more preferably 6% by mass or more and 12% by mass or less.

[0042] The rust-preventive composition of this embodiment, applied by spraying onto the underbody, running parts, structural components, and joints of an automobile body, offers excellent operability and rust prevention. It is particularly effective at preventing rust on joints. Furthermore, it exhibits excellent corrosion resistance and prevents liquid dripping from the vehicle body.

[0043] Furthermore, the volatile organic solvent in the rust-preventive composition of this embodiment can be 10% by mass or less. Preferably, it is 5% by mass or less. Organic solvents refer to compounds such as hydrocarbons (e.g., n-hexane), halogenated hydrocarbons (e.g., trihalomethanes, trichloroethylene, tetrachloroethylene), aromatic hydrocarbons (e.g., benzene, toluene, xylene, trimethylbenzene), and polycyclic aromatic hydrocarbons (aromatic compounds having three or more benzene rings, such as benzo[a]pyrene), especially compounds harmful to the natural environment and living organisms. The volatile organic solvent can be determined by measuring the mass of the organic compounds that evaporate when the rust-preventive composition is placed at 110°C for 1 hour, or based on the mass of the non-volatile components. Since the rust-preventive composition may also contain water, the volatile components may sometimes also contain water. The non-volatile components of the rust-preventive composition of this embodiment when placed at 110°C for 1 hour are preferably 95% by mass or more, more preferably 97% by mass or more.

[0044] The rust-preventive composition of this embodiment, even when applied as a thick film, can suppress sagging even at high temperatures above the melting point of the contained wax. According to the rust-preventive composition of this embodiment, a rust-preventive film with a thickness of 200 μm or more, particularly 300 μm or more, and particularly 400 μm or more, can be formed on automotive parts, etc. Furthermore, the thickness of the rust-preventive film formed by the rust-preventive composition is the thickness of the film after a stable film has been formed following the application of the rust-preventive composition. Therefore, the rust-preventive composition of the present invention is particularly suitable for forming a rust-preventive coating with a thickness of 200 μm or more on automotive parts, etc., made of steel, etc. Furthermore, even at plate joints where rust prevention is difficult to impart, high rust prevention can be achieved by using the rust-preventive composition of this embodiment.

[0045] Therefore, automotive parts having a rust-preventive film formed by the above-described rust-preventive composition are also one embodiment of the present invention.

[0046] Example

[0047] The present invention will now be described in more detail with reference to the embodiments, but the scope of the present invention is not limited to these embodiments.

[0048] <Preparation of Rust-Inhibiting Compositions>

[0049] The raw materials (mass %) shown in Table 1 were mixed with commercially available rust inhibitors, heated, and stirred. Afterward, they were allowed to cool naturally to obtain the rust inhibitor compositions of Examples 1-11 and Comparative Examples 1-4. The symbols in Table 1 used to prepare the rust inhibitor compositions represent the following raw materials. Additionally, dehydrated polymerized castor oil was used as the hardening oil, and calcium carbonate was used as the filler.

[0050] (B1) Microcrystalline wax

[0051] (B2) Ethylene-propylene copolymer

[0052] (E1) Mineral oil-based lubricating oil (kinematic viscosity at 40℃ is 20 mm) 2 / s)

[0053] (E2) Mineral oil-based lubricating oil (kinematic viscosity at 40℃ is 10 mm) 2 / s)

[0054] (E3) Mineral oil-based lubricating oil (kinematic viscosity at 40℃ is 30 mm) 2 / s)

[0055] (E4) Mineral oil-based lubricating oil (kinematic viscosity at 40℃ is 100 mmHg) 2 / s)

[0056] (E5) Mineral oil-based lubricating oil (kinematic viscosity at 40℃ is 220 mmHg) 2 / s)

[0057] [Table 1]

[0058]

[0059] <Rust Prevention Evaluation>

[0060] The rust-preventive compositions of Examples 1-11 and Comparative Examples 1-4 were applied using a bar coater to a 50 μm thick coating on 70×150×0.8 mm cold-rolled steel sheet (JIS G 3141SPCC-SD) that had been degreased with solvent (mineral oil concentrate) and dried. After drying at room temperature for 72 hours, a neutral salt spray test was conducted for a maximum of 720 hours to determine the time until rust formation. The rust prevention performance was then evaluated according to the following evaluation criteria. The results are shown in Table 2. "A" or higher is considered acceptable.

[0061] S: No rust after 720 hours

[0062] A: 480 hours or more but less than 720 hours

[0063] B: 240 hours or more but less than 480 hours

[0064] <Evaluation of Internal Rust Resistance of Joint Surfaces>

[0065] Prepare an alloyed hot-dip galvanized steel sheet of 70 (horizontal) × 150 (vertical) × 0.8 mm (hereinafter referred to as A steel sheet) and an alloyed hot-dip galvanized steel sheet of 40 (horizontal) × 70 (vertical) × 0.8 mm (hereinafter referred to as B steel sheet). In a state of overlapping such that it is 60 mm above and 20 mm below the longitudinal direction of the A steel sheet and at the central part in the transverse direction, spot welding is performed at two positions 23 mm and 46 mm above the longitudinal direction at the central part in the transverse direction of the B steel sheet. After adjusting the gap of the joint part to 200 - 300 μm, electro-deposition coating is performed on the test piece in the plate joint state (using electrophoretic coating PN1010 manufactured by Nippon Paint Co., Ltd.) to produce a test piece for the anti-rust test inside the joint.

[0066] Spray the anti-rust compositions of Examples 1 - 11 and Comparative Examples 1 - 4 onto the plate joint surface of the above-mentioned anti-rust test piece so that the film thickness is 100 μm. Use a composite cycle testing machine to repeat the cycle test with a neutral salt spray test for 4 hours, forced drying at 70°C for 5 hours, wetting test for 12 hours, forced drying at 70°C for 2 hours, and natural drying for 1 hour as one cycle. After the test, peel the welding at the joint part and find out the number of cycles until the joint part rusts. Then, evaluate the anti-rust property inside the joint surface according to the following evaluation criteria. The results are shown in Table 2. In addition, being "A" or above is qualified.

[0067] S: No rusting after 90 cycles or more

[0068] A: 60 cycles or more and less than 90 cycles

[0069] B: 30 cycles or more and less than 60 cycles

[0070] C: Less than 30 cycles

[0071] <Film retention evaluation>

[0072] Prepare an electro-deposition coated plate of 70 × 150 × 0.8 mm (manufactured by Baltec Corporation). After removing the oil content with a solvent (mineral spirits) and drying, mask the lower half of the test piece, and use a rod coater to apply the anti-rust composition sample to the upper half. Produce a coated plate with a minimum film thickness of 500 μm, increasing the film thickness by 100 μm each time up to 800 μm. Then, after natural drying for 4 hours in a state horizontal to the ground, peel the mask and heat at 80°C for 30 minutes in a state vertical to the ground, and check the film thickness at which sagging occurs. Then, evaluate the film retention according to the following evaluation criteria. The results are shown in Table 2. In addition, being "A" or above is qualified.

[0073] S: No sagging at 800 μm

[0074] A: 700 μm or more and less than 800 μm

[0075] B: Above 600μm and below 700μm

[0076] C: Less than 600μm

[0077] <Effusion Assessment>

[0078] Two 70×150×0.8mm electrodeposited coating plates (manufactured by Bartek Co., Ltd.), which had been degreased and dried with solvent (mineral oil), were overlapped. A portion (70×30mm) of one electrodeposited coating plate was bent at a 30-degree angle. The plate was then fixed in place with a clamp to prepare a test material for evaluating exudation. With the test material vertically upright relative to the ground (with the unoverlapped portion as the top), 24 μl of the rust-preventive compositions of the respective examples and comparative examples were injected from above into the overlapping portion of the two electrodeposited coating plates using a micro-syringe. The mixture was then left to stand at 20°C for 48 hours. Afterward, the clamp was removed, the exudation length was measured, and the exudation performance was evaluated according to the following evaluation criteria. The results are shown in Table 2. "A" or higher is considered acceptable.

[0079] S: 25mm and above

[0080] A: 20mm or more but less than 25mm

[0081] B: 15mm or more but less than 20mm

[0082] C: Less than 15mm

[0083] [Table 2]

[0084]

[0085] Furthermore, although the present invention has been described in detail with reference to specific embodiments, it will be apparent to those skilled in the art that various modifications and alterations can be made without departing from the spirit and scope of the present invention.

Claims

1. A rust-preventive composition comprising a rust-preventive additive, a wax, bentonite, a hardened oil, and two or more diluents of different viscosities, wherein the wax is selected from polyethylene-based or polypropylene-based synthetic waxes, or microcrystalline waxes, and has a melting point in the range of 60°C or higher and 130°C or lower. The rust-preventive composition comprises the rust-preventive additive in an amount ranging from 12% to 39% by mass relative to the total composition, bentonite in an amount ranging from 2% to 6% by mass relative to the total composition, and wax in an amount ranging from 3% to 13% by mass relative to the total composition. The content of the two or more diluents with different viscosities relative to the total rust-preventive composition is 33% by mass or more and 60% by mass or less. The kinematic viscosity of the diluent with the lowest viscosity among the two or more diluents with different viscosities is 10 mmHg at 40°C. 2 / s or higher and 30mm 2 In the range below / s, Among the two or more diluents with different viscosities, the diluent with the highest viscosity has a kinematic viscosity of 50 mmHg at 40°C. 2 / s or more The rust-preventive composition contains the diluent with the lowest viscosity among two or more diluents of different viscosities, which are in the range of 40% to 80% by mass relative to the total amount of diluent.

2. An automotive component having a rust-preventive coating formed from the rust-preventive composition of claim 1.

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