Temporary rust-preventive paint composition, aerosol product, and metal rust-preventive coating method

Abstract

To provide a temporarily rust-preventing coating composition which can achieve excellent rust-preventing property, peeling persistence and coating film formability, an aerosol product, and a metal rust-preventing coating method using them.SOLUTION: A temporarily rust-preventing coating composition contains a vinyl chloride-vinyl acetate copolymer resin, a plasticizer, a solvent, a vinyl chloride stabilizer and a weathering stabilizer. A K value of the vinyl chloride-vinyl acetate copolymer resin is 48 or more and 59 or less. The solvent is a mixed solvent containing a ketone-based solvent, an acetate-based solvent and an alcohol-based solvent. In the mixed solvent, a solubility parameter (SP value (δm)[cal / cm3]1 / 2) of the mixed solvent defined by Expression (1): δm=(φ1δ12+φ2δ22...+φnδn2)1 / 2 (In Expression (1), φ1, φ2... and φn represent a mass ratio of each of the solvents in the mixed solvent, and δ1, δ2... and δn represent a solubility parameter (SP value) of each of the solvents.) is 9.0 (cal / cm3)1 / 2 or more and 9.5 (cal / cm3)1 / 2 or less.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a temporary rust-preventive coating composition, an aerosol product, and a metal rust-preventive coating method that can be applied to a metal surface to form a coating film, temporarily suppress rust and protect the substrate surface, and allow the coating film to be easily peeled off at any time. It is particularly suitable for surface protection of weld grooves in steel materials until welding is performed. [Background technology]

[0002] When welding steel materials, the groove is first machined to a predetermined shape before welding. However, if there is a delay before welding, or if welding is performed at a construction site, rust may form on the groove surface. If welding is performed in this state, welding defects such as blowholes and pinholes will occur. Therefore, regrinding or regrinding of the groove surface may be necessary. For this reason, when there is a delay before welding, the application of rust-preventive paint is used. Examples of paints include alkyd resin-based paints. While such rust prevention measures prevent rust formation on the groove, if welding is performed with the paint still on, it may lead to the generation of combustion gases from the paint, the inclusion of non-metallic inclusions and other impurities in the weld metal, resulting in welding defects such as blowholes and pinholes, and a decrease in weld strength. This necessitates paint removal work, such as burning with flame, dissolution with chemicals, or mechanical grinding. To reduce the complicated removal work using chemicals and paint stripping machines, easily removable paints are used. Easy-peel coatings are required to have the following properties: the coating applied to the surface of the substrate adheres to it until it has achieved its purpose and is peeled off, thus preventing rust, protecting, and coloring the substrate surface; the ease of peeling does not decrease over time and can be easily peeled off as a continuous film at any time; the coating has good tensile strength (mechanical strength), elongation, water resistance, and weather resistance; the coating is easy to apply to form the film; and it dries quickly after application and has good film-forming properties. Various easy-peel coatings have been proposed to date.

[0003] Conventionally, a method is known in which a coating formed from a coating composition containing a vinyl chloride / vinyl acetate copolymer with a molecular weight of 300 to 50,000 is irradiated with light or ionizing radiation to reduce the adhesion between the coating and the substrate, thereby making it easy to peel off (see Patent Document 1). Also known is an aqueous primary protective coating composition containing a copolymer emulsion obtained by reacting a monomer mixture comprising a conjugated diene monomer and a polymerizable monomer copolymerizable therewith (see Patent Document 2). Furthermore, easily peelable coating compositions containing polyvinyl acetal resin, plasticizers, mold release agents, and organic solvents are also known (see Patent Document 3). [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 55-80476 [Patent Document 2] Japanese Patent Publication No. 2001-181558 [Patent Document 3] Japanese Patent Application Publication No. 5-112742 [Overview of the project] [Problems that the invention aims to solve]

[0005] However, Patent Document 1 requires a light irradiation device or electron beam irradiation device for peeling the coating, making it difficult to apply to construction sites and other similar environments. Furthermore, the water-based primary protective coating composition described in Patent Document 2 has the problem of long drying times due to its water solvent and the potential for rust formation on metals. Moreover, the organic solvent-based peelable coating composition described in Patent Document 3 has poor weather resistance, with the rust prevention properties of the coating deteriorating after several weeks of outdoor exposure, making peeling difficult. In addition, when applied in high-humidity environments, the coating condenses, causing whitening, reduced rust prevention, and poor appearance, making it impractical.

[0006] The present invention has been made in view of the problems of such prior art, and an object thereof is to provide a temporary rust preventive paint composition, an aerosol product, and a metal rust preventive coating method using these, which can achieve excellent rust prevention properties, peeling durability, and film forming properties.

Means for Solving the Problems

[0007] As a result of intensive studies to achieve the above object, the present inventors have found that in a temporary rust preventive paint composition containing a vinyl chloride-vinyl acetate copolymer resin, a plasticizer, a solvent, a vinyl chloride stabilizer, and a weather stabilizer, by setting the K value of the vinyl chloride-vinyl acetate copolymer resin within a predetermined range, using a mixed solvent containing a ketone solvent, an acetate solvent, and an alcohol solvent, and further setting the solubility parameter of the mixed solvent within a predetermined range, the above object can be achieved, and the present invention has been completed.

[0008] That is, the temporary rust preventive paint composition of the present invention contains a vinyl chloride-vinyl acetate copolymer resin (A), a plasticizer (B), a solvent (C), a vinyl chloride stabilizer (D), and a weather stabilizer (E). The K value determined based on JIS K7367-2 of the vinyl chloride-vinyl acetate copolymer resin (A) is 48 or more and 59 or less. The solvent (C) is a mixed solvent containing a ketone solvent, Glycol ether an acetate solvent, and Glycol ether-based solvents an alcohol solvent. In the mixed solvent, the solubility parameter (SP value (δ m ) [cal / cm 3 ) of the mixed solvent defined by the following formula (1) is 9.0 (cal / cm 1 / 2 ) 3 ) or more and 9.5 (cal / cm 1 / 2 ) 3 ) or less. The temporary rust preventive paint composition is characterized by this. 1 / 2 δ = (φ1δ1 m + φ2δ2 2 ··· + φ 2 δ n n 2 1 / 2 ) 1 / 2 ··· (1) (In formula (1), φ1, φ2..., φ n The terms δ1, δ2, δ1, δ2···, δ1 indicate the mass ratio of each solvent in the mixed solvent. n This shows the solubility parameter (SP value) of each solvent.

[0009] Furthermore, the aerosol product of the present invention is characterized by being prepared by filling a container with the above-mentioned temporary rust-preventive paint composition and a temporary rust-preventive paint composition for aerosols containing a propellant.

[0010] Furthermore, the metal rust-preventive coating method of the present invention is characterized by applying the above-mentioned temporary rust-preventive coating composition or a temporary rust-preventive coating composition for aerosols to a metal surface so that the dry film thickness is 10 to 500 μm. [Effects of the Invention]

[0011] According to the present invention, in a temporary rust-preventive coating composition comprising a vinyl chloride-vinyl acetate copolymer resin, a plasticizer, a solvent, a vinyl chloride stabilizer, and a weather-resistant stabilizer, the K value of the vinyl chloride-vinyl acetate copolymer resin is within the above range, and the solvent is a ketone-based solvent. Glycol ether Acetate-based solvents and Glycol ether-based solvents By using a mixed solvent containing the above-mentioned components, and further setting the solubility parameters of the mixed solvent within the above-mentioned range, it is possible to provide a temporary rust-preventive coating composition, an aerosol product, and a metal rust-preventive coating method using these, which can achieve excellent rust prevention, peel-resistant properties, and film-forming properties. [Modes for carrying out the invention]

[0012] The following describes in detail one embodiment of the present invention: a temporary rust-preventive coating composition, an aerosol product, and a metal rust-preventive coating method using these.

[0013] [Temporary rust-preventive paint composition] The temporary rust-preventive coating composition of this embodiment contains a vinyl chloride / vinyl acetate copolymer resin (A), a plasticizer (B), a solvent (C), a vinyl chloride stabilizer (D), and a weather-resistant stabilizer (E).

[0014] In this embodiment, the K value of the vinyl chloride-vinyl acetate copolymer resin (A), determined according to JIS K7367-2, is 48 or more and 59 or less, preferably 55 or more and 59 or less.

[0015] Furthermore, in this embodiment, solvent (C) is a ketone-based solvent. Glycol ether Acetate-based solvents and Glycol ether-based solvents A mixed solvent containing the following, and in the mixed solvent, the solubility parameter (SP value (δ) of the mixed solvent is defined by the following formula (1) m )[cal / cm 3 ] 1 / 2 ) is 9.0 (cal / cm³). 3 ) 1 / 2 More than 9.5(cal / cm 3 ) 1 / 2 The following applies:

[0016] δ m =(φ1δ1 2 +φ2δ2 2 ···+φ n δ n 2 ) 1 / 2 ... (1) (In formula (1), φ1, φ2..., φ n The terms δ1, δ2, δ1, δ2···, δ1 indicate the mass ratio of each solvent in the mixed solvent. n This shows the solubility parameter (SP value) of each solvent.

[0017] Next, the advantages of this embodiment will be described. According to this embodiment, since the K value of the vinyl chloride / vinyl acetate copolymer resin (A) in the temporary rust-preventive paint composition having the above-described composition is within the above-described range, and the solubility parameter of the above-described mixed solvent is within the above-described range, excellent rust prevention, peel-resistant properties, and film-forming properties can be achieved. Furthermore, if the above-described K value is within the range of 55 to 59, even better rust prevention and peel-resistant properties can be achieved.

[0018] In particular, when the temporary rust-preventive coating composition is applied directly to a metal surface, excellent rust prevention, peelability, and film formation can be achieved. A suitable example of such a metal surface is the welded groove of a steel material. When the welded groove of a steel material part is processed in a factory and then welded at a site separate from the factory, long-term rust prevention of the coating is required. Furthermore, if welding is performed with the coating still in place, it can lead to welding defects such as blowholes, pinholes, and hydrogen cracking, as well as a decrease in weld strength, thus requiring durable peelability of the coating. With the coating formed on the welded groove using the temporary rust-preventive coating composition of this embodiment, the occurrence of rust on the metal surface is suppressed, and the coating can be easily removed without requiring complicated or unsuitable removal work such as incineration with flame, dissolution with chemicals, mechanical polishing, or irradiation with light or ionizing radiation.

[0019] If the K value of vinyl chloride / vinyl acetate copolymer resin (A) is less than 48, the strength of the temporary rust-preventive coating film decreases, its peelability decreases, and it becomes more susceptible to oxidative degradation over time, resulting in reduced peelability. Furthermore, its rust-preventive properties also decrease. If the K value of vinyl chloride / vinyl acetate copolymer resin (A) exceeds 59, its molecular weight exceeds 100,000, reducing its solubility in mixed solvents and making it difficult to apply to paints. In addition, the actual manufacturing of the resin itself becomes difficult.

[0020] Furthermore, the solubility parameter of the mixed solvent (SP value (δ) m )) is 9.0 (cal / cm 3 ) 1 / 2 If the value is less than δ, the solubility of the vinyl chloride / vinyl acetate copolymer resin (A) in the mixed solvent decreases, making it difficult to apply to paints. Furthermore, a problem arises where the suitability for spray painting (paint film texture), which is one aspect of film formation, deteriorates. Additionally, another problem arises where whitening occurs during high-humidity painting, which is another aspect of film formation. Meanwhile, the solubility parameter (SP value (δ) of the mixed solvent... m )) is 9.5 (cal / cm 3 ) 1 / 2If the value exceeds this, the solubility of the vinyl chloride / vinyl acetate copolymer resin (A) in the mixed solvent decreases rapidly, making it difficult to apply to paints.

[0021] Here, we will explain in more detail the material types and specifications of each component.

[0022] (Vinyl chloride / vinyl acetate copolymer resin (A)) The vinyl chloride-vinyl acetate copolymer resin (A) is not particularly limited as long as its constituent units are vinyl chloride and vinyl acetate.

[0023] In vinyl chloride / vinyl acetate copolymer resin (A), the molecular weight is preferably 75,000 to 100,000, and more preferably 90,000 to 95,000, from the viewpoint of exhibiting superior rust prevention and peel-resistant properties.

[0024] Furthermore, the composition ratio of vinyl acetate in the vinyl chloride / vinyl acetate copolymer resin (A) is preferably 5 to 25% by mass, and more preferably 10 to 16% by mass, from the viewpoint of exhibiting better rust prevention and peel-resistant properties.

[0025] Furthermore, the degree of polymerization in the vinyl chloride / vinyl acetate copolymer resin (A) is preferably 400 to 800, and more preferably 600 to 800, from the viewpoint of exhibiting superior rust prevention and peel-resistant properties. Suitable examples of such vinyl chloride / vinyl acetate copolymer resin (A) include KaneVinyl® M series manufactured by Kaneka Corporation and Solvine® C grade manufactured by Nisshin Chemical Industry Co., Ltd.

[0026] (Plasticizer (B)) Suitable examples of plasticizers (B) include phthalate esters and aliphatic dibasic acid esters. These may be used individually or in combination of two or more. Among these, phthalate ester plasticizers are preferred from the viewpoint of exhibiting superior rust prevention and peel-resistant properties.

[0027] (Solvent (C)) As for solvent (C), ketone-based solvents, Glycol ether Acetate-based solvents and Glycol ether-based solvents The mixed solvent is not particularly limited as long as it contains the above-mentioned solubility parameters. Suitable examples of ketone solvents include methyl ethyl ketone and methyl isobutyl ketone. Ketone solvents may be used individually or in combination of two or more. Glycol ether Suitable acetate-based solvents include, for example, propylene glycol monomethyl ether acetate and 3-methyl 3-methoxybutyl acetate. Glycol ether Acetate-based solvents may be used individually or in combination of two or more types. Furthermore, Glycol ether-based solvents Suitable examples include propylene glycol monomethyl ether and 3-methyl 3-methoxybutanol. Glycol ether-based solvents One type may be used alone, or two or more types may be used in combination.

[0028] As a mixed solvent, the content of ketone-based solvents in the total amount of solvent is 50% by mass or more and 80% by mass or less. Glycol ether The content of acetate-based solvents is 10% by mass or more and 45% by mass or less. Glycol ether-based solvents It is preferable to use a mixed solvent having a content of 5% by mass or more and 20% by mass or less.

[0029] If the ketone solvent content is less than 50% by mass, the solubility of vinyl chloride / vinyl acetate copolymer resin (A) in the mixed solvent may decrease. Furthermore, if the ketone solvent content exceeds 80% by mass, whitening of the paint film may occur during painting in high-humidity environments. Additionally, the suitability for spray painting (paint film texture) may also decrease.

[0030] Glycol ether If the acetate-based solvent content is less than 10% by mass, the suitability for spray painting (coating surface) may decrease. Also, Glycol etherIf the acetate solvent content exceeds 45% by mass, the solubility of vinyl chloride / vinyl acetate copolymer resin (A) in the mixed solvent may decrease.

[0031] Glycol ether-based solvents If the content is less than 5% by mass, it may cause whitening of the paint film during painting in high-humidity environments. Also, Glycol ether-based solvents If the content exceeds 20% by mass, the solubility of vinyl chloride / vinyl acetate copolymer resin (A) in the mixed solvent may decrease.

[0032] Furthermore, in the temporary rust-preventive paint composition, it is preferable that the composition contains 10 to 50 parts by mass of plasticizer (B) and 300 to 900 parts by mass of solvent (C) per 100 parts by mass of vinyl chloride / vinyl acetate copolymer resin (A).

[0033] If the proportion of plasticizer (B) per 100 parts by mass of vinyl chloride / vinyl acetate copolymer resin (A) is less than 10 parts by mass, film-forming properties and rust prevention (corrosion resistance) may decrease, and the coating may become more prone to tearing during peeling. Furthermore, if the proportion of plasticizer (B) per 100 parts by mass of vinyl chloride / vinyl acetate copolymer resin (A) exceeds 50 parts by mass, the coating may become softer, and peelability and rust prevention (corrosion resistance) may decrease.

[0034] If the blending ratio of solvent (C) is less than 300 parts by mass per 100 parts by mass of vinyl chloride / vinyl acetate copolymer resin (A), the viscosity may increase when dissolving the vinyl chloride / vinyl acetate copolymer resin (A) in the mixed solvent, making manufacturing difficult. Furthermore, if the blending ratio of solvent (C) exceeds 900 parts by mass per 100 parts by mass of vinyl chloride / vinyl acetate copolymer resin (A), it may become difficult to form a coating film with a dry film thickness of 10 μm or more in a single application.

[0035] (Vinyl chloride stabilizer (D)) As the vinyl chloride stabilizer (D), any conventionally known vinyl chloride stabilizer capable of suppressing the deterioration of vinyl chloride in the coating film can be used. Furthermore, from the viewpoint of exhibiting superior rust prevention and peel-resistant properties, the content of the vinyl chloride stabilizer (D) in the temporary rust-preventive coating composition is preferably, for example, 0.1% by mass or more and 2.0% by mass or less, and more preferably 0.5% by mass or more and 1.0% by mass or less.

[0036] (Weather stabilizer (E)) Suitable examples of weather stabilizers (E) include benzotriazole-based ultraviolet absorbers and triazine-based ultraviolet absorbers that can suppress the deterioration of the coating film due to ultraviolet rays. Among these, benzotriazole-based ultraviolet absorbers are preferred from the viewpoint of exhibiting superior rust prevention and peel-resistant properties. The content of weather stabilizers (E) in the temporary rust-preventive coating composition is preferably, for example, 0.1% by mass or more and 5.0% by mass or less, and more preferably 0.5% by mass or more and 2.0% by mass or less, from the viewpoint of exhibiting superior rust prevention and peel-resistant properties.

[0037] [Aerosol Products] The aerosol product of this embodiment is prepared by filling a container with the above-mentioned temporary rust-preventive paint composition and the aerosol temporary rust-preventive paint composition containing a propellant.

[0038] Suitable propellants for this aerosol product include dimethyl ether and liquefied petroleum gas (LPG). The ratio of the primary rust-preventive coating composition to the propellant is preferably 30-60 / 40-70 (by volume). The internal pressure of the aerosol container is preferably 0.2 MPa or higher at 25°C and 0.8 MPa or lower at 35°C. If the internal pressure of the aerosol container is less than 0.2 MPa at 25°C, painting with the aerosol product may become difficult. Furthermore, if the internal pressure of the aerosol container exceeds 0.8 MPa at 35°C, it is not practical as it does not meet the standards of the General High-Pressure Gas Safety Regulations for Aerosol Manufacturing.

[0039] The advantage of the aerosol product of this embodiment is that a coating film having the advantages of the above-described temporary rust-preventive paint composition can be quickly obtained by spray painting at a metalworking site without the need to prepare painting tools.

[0040] [Method for applying metal rust-preventive coating (Method for applying temporary rust-preventive paint composition)] The temporary rust-preventive coating composition of this embodiment can be applied using conventional painting tools such as brushes, rollers, and air sprayers. Aerosol products can also be applied directly by spraying. In this embodiment, it is preferable to achieve a dry film thickness of 10 to 500 μm after application.

[0041] If the dry film thickness of the coating is less than 10 μm, the rust prevention (corrosion prevention) may decrease, and the peelability, especially the peeling durability, may decrease. Furthermore, if the dry film thickness of the coating exceeds 500 μm, not only does it become difficult to achieve a finish in a single coat, but the material costs also increase. [Examples]

[0042] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

[0043] (Examples 1-7, Comparative Examples 1-9) [Paint manufacturing] Table 1 shows the vinyl chloride / vinyl acetate copolymer resin (A), plasticizer (B), solvent (C), vinyl chloride stabilizer (D), and weather-resistant stabilizer (E) that were prepared. In Table 1, "Kanevinyl" is manufactured by Kaneka Corporation, "Solvine" is manufactured by Nisshin Chemical Industry Co., Ltd., "ADEKA Stab (registered trademark) AO-503" is manufactured by ADEKA Corporation, "jER (registered trademark) 828" is manufactured by Mitsubishi Chemical Corporation, "ADEKA Stab LA-32" is manufactured by ADEKA Corporation, and "Chinubin (registered trademark) 1130" and "Chinubin 400" are manufactured by BASF.

[0044] Solvent (C) was mixed in a stainless steel container, and vinyl chloride / vinyl acetate copolymer resin (A) was added while stirring with a disperser until uniformly dissolved. Then, a plasticizer (B), vinyl chloride stabilizer (D), and weather-resistant stabilizer (E) were added as needed to obtain the temporary rust-preventive coating compositions for each example.

[0045] [Aerosol filling] In Example 5, a propellant (dimethyl ether) was added to the temporary rust-preventive coating composition in a ratio of 45 / 55 of propellant to the temporary rust-preventive coating composition (volume ratio). The mixture was then filled into a container to an internal pressure of approximately 0.4 MPa to obtain the aerosol product of this example.

[0046] [Painting and test specimen preparation] A mild steel plate (thickness: 0.8 mm; width: 70 mm; length: 150 mm) used as a test plate was degreased with toluene, then polished with an abrasive (#320), and degreased again with toluene. The degreased test plate was then coated with the temporary rust-preventive coating composition for each example using an air spray to achieve a predetermined dry film thickness, thereby obtaining the test specimen for each example. In Example 5, the degreased test plate was coated with the aerosol-type temporary rust-preventive coating composition obtained as described above using an aerosol product to achieve a predetermined dry film thickness, thereby obtaining the test specimen for this example.

[0047] [Table 1]

[0048] [Testing and Evaluation] The following tests and evaluations were performed on each test specimen.

[0049] <Rust prevention> The edges and back of the test specimens were coated with commercially available epoxy paint and dried at room temperature for 7 days. Then, a 30mm vertical cut was made in the center of the specimen using a utility knife, and an outdoor exposure test (south-facing, 30°) was conducted. Rust was evaluated after 3 months. The results obtained are shown in Table 1. In Table 1, for this item, "A" indicates that the rust width of the cut section was less than 2 mm on one side and the rust area of ​​the general section was less than 0.1%, "B" indicates that the rust width of the cut section was less than 3 mm on one side and the rust area of ​​the general section was 0.1% or more but less than 1%, "C" indicates that the rust width of the cut section was less than 4 mm on one side and the rust area of ​​the general section was 1% or more but less than 10%, and "D" indicates that the rust width of the cut section was less than 4 mm on one side and the rust area of ​​the general section was 10% or more. Furthermore, ASTM D 610 was used as a reference for evaluating the rust area.

[0050] <Peel-resistant properties> The edges and back surface of the test specimens were coated with commercially available epoxy paint, dried at room temperature for 7 days, and then subjected to an outdoor exposure test (south-facing, 30°). After 3 and 6 months, 20 mm wide cuts were made horizontally across the surface of the test specimens using a utility knife, cellophane tape was applied to one end, and the paint film was slowly peeled off. The results obtained are shown in Table 1. In Table 1, for this item, "A" indicates that after 6 months, the paint film could be easily peeled off in lengths of 30 mm or more; "B" indicates that after 3 months, the paint film could be easily peeled off in lengths of 30 mm or more, but after 6 months, it became difficult; "C" indicates that after 3 months, the paint film could be peeled off, but it broke before reaching 30 mm; and "D" indicates that after 3 months, it was difficult to peel off the paint film.

[0051] <Suitability for spray painting (coating finish)> The surface texture of the coating on the test specimens was visually evaluated. The results are shown in Table 1. In Table 1, for this item, "A" indicates a smooth painted surface with sufficient gloss, "B" indicates a nearly smooth painted surface with slightly less gloss but no practical problems, "C" indicates some residual bubbles due to air entrapment during painting and an unsmooth painted surface, and "D" indicates significant residual bubble marks due to air entrapment during painting.

[0052] <Whitening during painting in high-humidity environments> The test specimens, immediately after painting, were left to stand for 1 hour in a box at 23°C with a relative humidity of 95% or higher. After drying for 2 hours in an environment at 23°C with a relative humidity of 50-70%, the whitening state of the paint film surface was observed. The results obtained are shown in Table 1. In Table 1, for this item, "A" indicates that slight whitening was observed immediately after removal from the high-humidity box, but it became transparent after about 5 minutes; "B" indicates that whitening was observed immediately after removal from the high-humidity box, but it became transparent within 20 minutes; "C" indicates that considerable whitening was observed immediately after removal from the high-humidity box, and some whitening remained even after 2 hours; and "D" indicates that considerable whitening was observed after removal from the high-humidity box, and the whitening remained even after 2 hours.

[0053] As shown in Table 1, Examples 1 to 7, which fall within the scope of the present invention, can achieve superior rust prevention, peel-resistant properties, and coating film formation properties compared to Comparative Examples 1 to 9, which fall outside the scope of the present invention.

[0054] Specifically, the coating obtained by applying the temporary rust-preventive coating compositions of Examples 1 to 7 to a metal surface is strong and has moderate elongation, suppresses rust formation on the metal even when left outdoors for a long period of time, and can be easily peeled off from the metal surface as a continuous film without breaking.

[0055] Among these, Examples 1, 3 to 7, in which the plasticizer (B) is a phthalate ester type, are preferred.

[0056] Furthermore, among these, Examples 1 to 3 and Examples 5 to 7, in which the weather stabilizer (E) is a benzotriazole-based ultraviolet absorber, are preferred.

[0057] Furthermore, among these, Examples 1 to 3 and Examples 5 to 7 are preferred, as their blending ratios in the mixed solvent are within the preferred range described above. Note that in Example 4, Glycol ether The blending ratio of the acetate-based solvent is not within the preferred range described above.

[0058] Furthermore, among these, Examples 1 to 7, in which the blending ratio of plasticizer (B) and solvent (C) is within the above-mentioned preferred range, are preferred.

[0059] Furthermore, among these, Examples 1 to 5 and 7, in which the coating film thickness is within the preferred range described above, are preferred.

[0060] On the other hand, the coating obtained by applying the temporary rust-preventive coating composition of Comparative Example 1 to a metal surface has a K value of 60, which is above 59, for the vinyl chloride / vinyl acetate copolymer resin (A), and is therefore inferior in terms of peel durability and suitability for spray coating. Furthermore, Comparative Example 2 has a K value of 45, which is below 48, and is therefore inferior in terms of rust prevention and peel durability.

[0061] Furthermore, Comparative Example 3 is inferior in terms of rust prevention and peel-resistant properties because the vinyl chloride / vinyl acetate copolymer resin (A) contains vinyl alcohol other than vinyl chloride and vinyl acetate as constituent units of the copolymer resin.

[0062] Furthermore, Comparative Example 4 shows the solubility parameter (SP value (δ) of the mixed solvent. m )) is 8.8 (cal / cm 3 ) 1 / 2 9.0 (cal / cm³) 3 ) 1 / 2 Since it is less than [value], it is inferior in terms of suitability for spray coating (coating surface), which is one aspect of coating film formation, and in terms of whitening during high-humidity coating, which is another aspect. In addition, Comparative Example 5 has a solubility parameter (SP value (δ) of the mixed solvent. m )) is 9.6 (cal / cm 3 ) 1 / 2 9.5 (cal / cm³) 3 ) 1 / 2 Because it is larger, it is inferior in terms of suitability for spray coating (coating surface), which is one aspect of coating film formation. In Comparative Example 5, Glycol ether Acetate-based solvents and Glycol ether-based solvents The proportion of the compound is not within the preferred range described above.

[0063] Furthermore, Comparative Example 6 is inferior in terms of rust prevention and peel durability because it does not contain plasticizer (B). Also, Comparative Example 7 is inferior in terms of rust prevention and peel durability because it does not contain vinyl chloride stabilizer (D). Furthermore, Comparative Example 8 is inferior in terms of rust prevention and peel durability because it does not contain weather-resistant stabilizer (E).

[0064] Furthermore, at present, Examples 1, 5, and 7 yield the best results in terms of rust prevention, peel-off durability, and coating film formation.

Claims

1. A temporary rust-preventive coating composition comprising a vinyl chloride / vinyl acetate copolymer resin (A), a plasticizer (B), a solvent (C), a vinyl chloride stabilizer (D), and a weather-resistant stabilizer (E), The K value of the above vinyl chloride / vinyl acetate copolymer resin (A), determined according to JIS K7367-2, is 48 or more and 59 or less. The above solvent (C) is a mixed solvent containing a ketone solvent, a glycol ether acetate solvent, and a glycol ether solvent. In the above mixed solvent, the solubility parameter (SP value (δ) of the mixed solvent is defined by the following formula (1). ｍ ) [cal / cm ３ ] １／２ ) is 9.0 (cal / cm³). ３ ) １／２ More than 9.5 (cal / cm ３ ) １／２ A temporary rust-preventive coating composition characterized by the following: d ｍ =(φ １ d １ ２ +φ ２ d ２ ２ ・・・+φ ｎ d ｎ ２ ) １／２ ・・・ (1) (In formula (1), φ １ , φ ２ ..., φ ｎ This indicates the mass ratio of each solvent in the mixed solvent, δ １ , δ ２ ..., δ ｎ This shows the solubility parameter (SP value) of each solvent.

2. The temporary rust-preventive coating composition according to claim 1, characterized in that the plasticizer (B) is a phthalate ester type.

3. The temporary rust-preventive coating composition according to claim 1, characterized in that the weather-resistant stabilizer (E) is a benzotriazole-based ultraviolet absorber.

4. The temporary rust-preventive coating composition according to claim 1, characterized in that the above mixed solvent contains 50% by mass or more and 80% by mass or less of the ketone-based solvent, 10% by mass or more and 45% by mass or less of the glycol ether acetate-based solvent, and 5% by mass or more and 20% by mass or less of the glycol ether-based solvent.

5. The temporary rust-preventive coating composition according to claim 1, characterized in that it contains 10 to 50 parts by mass of the plasticizer (B) and 300 to 900 parts by mass of the solvent (C) per 100 parts by mass of the vinyl chloride / vinyl acetate copolymer resin (A).

6. An aerosol product characterized by filling a container with a temporary rust-preventive paint composition for aerosols containing a propellant and a temporary rust-preventive paint composition according to any one of claims 1 to 5.

7. A method for preventing rust on metal, characterized by applying a temporary rust-preventive coating composition according to any one of claims 1 to 5 to a metal surface so that the dry film thickness is 10 to 500 μm.

8. A method for preventing metal rust, characterized by applying the aerosol temporary rust-preventive coating composition described in claim 6 to a metal surface so that the dry film thickness is 10 to 500 μm.

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