JP2006291014A - Anticorrosive coating, plastic article, method for producing anticorrosive silver mirror film, and method for producing plastic article - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an anticorrosive coating capable of maintaining metallic luster of a mirror film and having high adhesion to a plastic material, and to provide a plastic article in which metallic luster by a silver mirror film is maintained, a method for producing an anticorrosive silver mirror film in which metallic luster is maintained, and a method for producing a plastic article. <P>SOLUTION: The anticorrosive coating comprises metal oxide particles having a particle size of 20-50 nm, an acrylic resin, and a silane coupling agent. The method for producing an anticorrosive silver mirror film comprises the steps of forming a silver mirror film by silver mirror reaction on an article to be coated and applying the anticorrosive coating on top of the silver mirror film. The method for producing a plastic article comprises the steps of forming a plastic material into an article having a specific shape and producing an anticorrosive silver mirror film by the method for producing an anticorrosive silver mirror film on the surface of the article. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

   The present invention relates to a rust-proof paint, a plastic article, a method for producing a rust-proof silver mirror film, and a method for producing a plastic article. In particular, a rust preventive paint suitable for preventing a silver mirror film from being coated on a silver mirror film, a plastic article coated with the anticorrosive paint, and a rust preventive silver mirror film coated with the rust preventive paint. The present invention relates to a manufacturing method and a manufacturing method of a plastic article in which a silver mirror film is formed by the manufacturing method of the rust-proof silver mirror film.

  In order to reduce the weight of products, plastic has been used for parts that previously used metals. In such plastic parts, it seems that it seems that it is made of metal, and it may suit consumers' preference, and there is a great demand for plastic coated with metallic luster. Therefore, coating using pulverized coal of aluminum has been conventionally performed. However, the cost of aluminum pulverized coal is high, and its use is limited.

  On the other hand, painting using silver mirror processing on the surface of plastic has attracted attention. In this coating, silver is deposited by a silver mirror reaction of a special primer applied to the surface of a plastic material to form a silver mirror film, thereby giving a metallic luster to the plastic product. Formation of this silver mirror film is easier to manufacture and less expensive than coating using aluminum pulverized coal.

  However, since the silver mirror film is the deposited silver itself, it is easily corroded by chlorine and the like and easily discolored. For this purpose, clear coating is applied to prevent corrosion of the silver mirror film, but it has been difficult to maintain the metallic luster of the silver mirror film and enjoy the design permanently. Therefore, the present invention aims to provide a rust preventive paint that can maintain the metallic luster of the silver mirror film and has high adhesion to the plastic material. It is an object of the present invention to provide an article, a method for producing a rust-proof silver mirror film that maintains a metallic luster, and a method for producing a plastic article.

  In order to achieve the above object, the rust preventive paint according to the invention of claim 1 has metal oxide particles having a particle diameter of 20 nm or more and 50 nm or less, an acrylic resin, and a silane coupling agent.

  If comprised in this way, since a rust preventive paint has a metal oxide particle, it has a high rust preventive effect, and since the metal oxide particle is 20 nm or more and 50 nm, it does not impair the transparency of a rust preventive paint. In addition, since the anticorrosive paint has an acrylic resin and a silane coupling agent, when used as a plastic material, the paint adherence increases together with the transparency of the paint, and the adhesion to the silver mirror film is excellent. In addition, since it has a rust prevention effect as described above, it is referred to as “rust preventive paint”, but it is not necessarily used for rust prevention.

  Moreover, like the rust preventive paint according to the invention described in claim 2, in the rust preventive paint according to claim 1, the metal oxide particles may include aluminum oxide particles or zinc oxide particles.

  If comprised in this way, since a metal oxide particle contains an aluminum oxide particle or a zinc oxide particle, and these metal oxide particles have especially a high rust prevention effect, it becomes a rust prevention paint with a higher rust prevention effect.

  In order to achieve the above-mentioned object, a plastic article according to a third aspect of the present invention includes, as shown in FIG. 1, for example, an article 12 made of a plastic material; and a silver mirror film formed on the surface of the article 12 14; and a film 16 of the anticorrosive paint according to claim 1 or 2 formed on the silver mirror film 14.

  If comprised in this way, the film | membrane of the antirust paint of Claim 1 or Claim 2 formed by overlapping the article | item formed with the plastic material, the silver mirror film formed on the surface of the article | item, and the silver mirror film | membrane. Thus, the metallic mirror has a metallic luster, and the anti-corrosive paint prevents the silver mirror film from being oxidized, so that the metallic luster is maintained.

  Moreover, in order to achieve the said objective, the manufacturing method of the antirust silver mirror film which concerns on invention of Claim 4 is shown, for example, as shown in FIG. 3, Process St12 which forms a silver mirror film by silver mirror reaction to to-be-coated article And a step St13 of applying the anticorrosive paint according to claim 1 over the silver mirror film.

  If comprised in this way, since it comprises the process of forming a silver mirror film in a to-be-coated article, and the process of apply | coating the anticorrosion paint of Claim 1 or Claim 2 over a silver mirror film, metallic luster of a silver mirror film Thus, a method for producing a rust-proof silver mirror film in which the silver mirror film is prevented from being oxidized by the rust-proof paint and the metallic luster is maintained.

  Moreover, in the manufacturing method of the antirust silver mirror film which concerns on invention of Claim 4, like the manufacturing method of the antirust silver mirror film which concerns on invention of Claim 5, as shown, for example in FIG. A step St15 of applying a top coating may be provided so as to overlap the antirust coating film applied in the step of applying coating St13.

  If comprised in this way, since it has the process of apply | coating top coat on the film | membrane of a rust preventive paint, the film of a rust preventive paint is protected and it becomes a manufacturing method of the rust preventive silver mirror film which is hard to receive damage.

  Furthermore, the manufacturing method of the plastic article according to the invention of claim 6 includes the step St11 of forming a plastic material into an article having a predetermined shape, as shown in FIG. 3, for example; The process St12-St13 which manufactures an antirust silver mirror film with the manufacturing method of an antirust silver mirror film of claim | item 5. are provided.

  If comprised in this way, the process of forming a plastic raw material in the article | item of a predetermined shape, and the process of manufacturing a rust prevention silver mirror film on the surface of an article with the manufacturing method of the rust prevention silver mirror film of Claim 4 or Claim 5, Therefore, it becomes the manufacturing method of the plastic article which has the metallic luster of the silver mirror film, prevents oxidation of the silver mirror film by the anticorrosive paint, and maintains the metallic luster.

  According to the present invention, since it has metal oxide particles having a particle diameter of 20 nm or more and 50 nm or less, an acrylic resin, and a silane coupling agent, it has a high antirust effect and impairs the transparency of the anticorrosion paint. There is provided a rust preventive paint having high adhesion to a plastic material and excellent adhesion to a silver mirror film. Moreover, by providing the film of the anticorrosive paint, a plastic article having the metallic luster of the silver mirror film and preventing the oxidation of the silver mirror film by the antirust paint and maintaining the metallic luster is provided. By having a step of forming a silver mirror film and a step of applying the above anticorrosion paint on the silver mirror film, the silver mirror film has a metallic luster, and the antirust coating prevents oxidation of the silver mirror film and a metallic luster. A method for producing a maintained antirust silver mirror film is provided, comprising the steps of forming a plastic material into an article having a predetermined shape, and producing the antirust silver mirror film on the surface of the article by the method for producing an antirust silver mirror film. By providing, the manufacturing method of the plastic article which has the metallic luster of a silver mirror film, the oxidation of a silver mirror film is prevented by a rust preventive paint, and a metallic luster is maintained is provided.

  Embodiments of the present invention will be described below with reference to the drawings. In the drawings, the same or equivalent devices are denoted by the same reference numerals, and redundant description is omitted.

  In FIG. 1, a silver mirror film 14 is formed on an article 12 made of plastic as an article to be coated (hereinafter simply referred to as “plastic 12”), and a rust-proof coating film 16 and an overcoat are formed thereon. The fragmentary sectional view of the plastic article 10 in which the film | membrane 18 was formed is shown. The plastic of the plastic article 10 is typically an acrylic resin such as ABS (acrylonitrile butadiene styrene) resin, AS (acrylonitrile styrene) resin, PMMA (polymethyl methacrylate), etc. Often, the resin is used mainly for applications that replace metal materials. The plastic article 10 is, for example, an automobile part, and is a home appliance part.

  The silver mirror film 14 is a film in which silver deposited by the silver mirror reaction is adhered to the surface of the plastic 12. In principle, ammonia water is added to an aqueous silver nitrate solution to produce diammine silver, aldehyde is added to reduce diammine silver, and a silver mirror film is formed from the deposited silver using a silver mirror reaction that deposits silver. It is. Since the silver mirror film is an almost pure silver film, it has a metallic luster.

  Here, a specific method of forming the silver mirror film 14 will be described with reference to the flowchart of FIG. Specially modified acrylic two-component clear coating for silver mirror reaction (for example, Origin Electric Co., Ltd., Origin Tsuk # 100 with a predetermined composition (main agent: 4 parts by mass / curing agent: 1 part by mass / solvent: 2 parts by mass)) Adjust and stir well (St1). After stirring, spray coating is applied to the surface of the plastic 12 (St2). Then, it is made to dry (St3). After drying, a sensitization treatment for promoting silver deposition is performed (St4). As the sensitization treatment, for example, it is immersed in a stannous chloride solution. Thereafter, a silver nitrate ammonia solution and a solution containing a reducing organic compound are simultaneously coated (St5) to deposit silver (St6). After silver deposition, the surface of the silver mirror film is washed away with sufficient pure water (St7) and dried (St8).

  Returning to FIG. 1, the description of the plastic article 10 will be continued. A rust preventive paint is applied on the silver mirror film 14 to form a rust preventive paint film 16. The antirust paint is a paint in which metal oxide particles having a particle diameter of 20 nm to 50 nm, an acrylic resin, and a silane coupling agent are dissolved in a solvent so as to have a predetermined solid content concentration. Examples of the solvent include ketone solvents such as acetone, methyl ethyl ketone, and dimethyl ethyl ketone, ester solvents such as ethyl acetate and butyl acetate, hydrocarbon solvents such as toluene, xylene, and naphtha, and alcohol solvents such as 2-butoxyethanol. A generally used solvent may be used.

  Examples of the metal oxide include aluminum oxide, silicon oxide, titanium oxide, zinc oxide, and tin oxide. As is generally known, metal oxide has an antirust effect. Among these, aluminum oxide and zinc oxide are preferable because they have a particularly strong antirust effect. The metal oxide particles may be composite metal oxide particles having two or more of aluminum oxide, silicon oxide, titanium oxide, zinc oxide, and tin oxide. Metal oxides are generally strong pigments, as are commonly used as pigments. However, by forming fine particles (so-called nanoparticles) having a particle diameter of 20 nm or more and 50 nm or less, a color does not appear on the coating film and it becomes colorless and transparent. Here, the particle diameter is an average particle diameter, and is obtained by simple average (average by number) of particle diameters measured with a transmission electron microscope (TEM), a scanning electron microscope (SEM), or the like. When the particle diameter is smaller than 20 nm, it becomes difficult to obtain an antirust effect. On the other hand, when the thickness is larger than 50 nm, the transparency decreases, it becomes difficult to obtain a colorless and transparent coating film, and the rust prevention effect is reduced. The particle diameter is preferably 30 nm or more and 40 nm or less because the transparency is higher and the rust prevention action is stronger.

An acrylic resin is a polymer obtained by polymerizing an acrylic monomer using a polymerization initiator. Examples of acrylic monomers include methyl acrylate, ethyl acrylate, propyl acrylate, isopropyl acrylate, butyl acrylate, hexyl acrylate, octyl acrylate, lauryl acrylate, methyl methacrylate, ethyl methacrylate, Acrylic acid or alkyl ester of methacrylic acid such as propyl methacrylate, isopropyl methacrylate, butyl methacrylate, hexyl methacrylate, octyl methacrylate, lauryl methacrylate; methoxybutyl acrylate, methoxybutyl methacrylate, methoxyethyl acrylate, methacryl Acrylic acid or methacrylic acid alkoxyalkyl ester such as methoxyethyl acid, ethoxybutyl acrylate, ethoxybutyl methacrylate; An alkenyl ester of acrylic acid or methacrylic acid such as acrylate; A hydroxyalkyl ester of acrylic acid or methacrylic acid such as hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxybutyl acrylate, hydroxybutyl methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate; Examples include alkenyloxyalkyl esters of acrylic acid or methacrylic acid such as acrylate and allyloxyethyl methacrylate; acrylamide, acrylonitrile, methacrylonitrile, acrylic acid, methacrylic acid, and the like. These may be used alone or in combination of two or more. In addition, these vinyl monomers may be used in combination with acrylic monomers. Other vinyl monomers include vinyl aromatic compounds such as styrene, α-methylstyrene, vinyltoluene and p-chlorostyrene; olefinic compounds such as butadiene, isoprene and chloroprene; vinyl acetate, allyl alcohol and maleic acid Is mentioned.
Examples of the polymerization initiator include peroxides such as benzoyl peroxide and t-butylperoxy-2-ethylhexanoate, and azo compounds such as azobisisobutyronitrile and azobisdimethylvaleronitrile. . In general, the plastic 12 contains an acrylic resin, and the rust preventive paint has an acrylic resin, whereby adhesion to the plastic 12 is enhanced and peeling is prevented.
The mass average molecular weight of the acrylic resin is preferably 30,000 to 45,000. If the mass average molecular weight of the acrylic resin is less than 30,000, the strength and water resistance of the resulting coating film may be lowered. If the mass average molecular weight of the acrylic resin exceeds 45,000, the viscosity of the paint increases and the coating workability may decrease. Here, the mass average molecular weight is a value in terms of styrene measured by gel permeation chromatography (GPC).

The silane coupling agent enables a cross-linking reaction with an acrylic resin and improves adhesion to the silver mirror film 14 and the top coat film 18.
The silane coupling agent may be any commonly used silane coupling agent, such as N- (2-aminoethyl) -3-aminopropyltrimethoxysilane, γ- (2-aminoethyl) aminopropyl. Trimethoxysilane, γ- (2-aminoethyl) aminopropylmethylmethoxysilane, γ-methacryloxypropyltrimethoxysilane, N-β- (N-vinylbenzylaminoethyl) -γ-aminopropylmethyldimethoxysilane hydrochloride, γ-glycidoxypropyltrimethoxysilane, γ-mercaptopropyltrimethoxysilane, methyltrimethoxysilane, methyltriethoxysilane, vinyltriacetoxysilane, γ-chloropropyltrimethoxysilane, hexamethyldisilazane, γ-anilino Propyltrimethoxy Emissions, vinyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane and the like. Among these, N- (2-aminoethyl) -3-aminopropyltrimethoxysilane is preferably used because of its high effect of improving the adhesion of the coating film to the silver mirror film.

  An overcoat film 18 is formed on the anticorrosive paint film 16 to protect the anticorrosive paint film 16. This is because the coating film 16 of the moisture-proof paint does not have a very large strength and is easily damaged. The top coat film 18 does not impair the metallic luster of the silver mirror film 14 and therefore needs to be a clear paint film, but may be a normal clear paint film. For example, a coating film such as a silicon acrylic paint may be used.

  As described above, by forming the silver mirror film 14, the anticorrosive paint film 16, and the top coat film 18 on the surface of the plastic 12, a metallic luster is obtained by the silver mirror film 14. The colorless and transparent anticorrosive coating film 16 prevents corrosion and discoloration of the silver mirror film 14 without impairing the metallic luster of the silver mirror film 14. Further, the metallic luster of the silver mirror film 14 is not impaired due to the clear coating while the coating 16 of the anticorrosive coating is protected by the top coating 18. Therefore, the metallic luster of the surface of the plastic 12 is maintained.

  Next, a method for manufacturing a plastic article having a metallic luster as described above will be described with reference to the flowchart of FIG. First, an article is manufactured from plastic by injection molding or the like (St11). Next, as described in FIG. 2, a silver mirror film is formed on the surface of the article made of plastic (St12). If the silver mirror film is formed, a rust preventive paint is applied on the silver mirror film (St13). The application of the rust preventive paint may be performed by a generally performed method such as spraying, flow coating, dipping, brushing, roll coating, or the like. Then, the rust preventive paint is dried (St14). Drying may be performed at room temperature or by heating. After the rust preventive paint is dried, the top coat paint is applied to the rust preventive paint film (St15) and dried to form a top coat film (St16). The top coating and drying may be performed by a generally performed method. With the above, a plastic article having a metallic luster is manufactured. The plastic article thus manufactured has a metallic luster on the surface, and the metallic luster is maintained. Moreover, the coating method is the same as the conventional method, and the coating can be easily performed only by changing the paint.

Hereinafter, the present invention will be described in more detail with reference to examples. First, transparency when the metal oxide particles are changed to aluminum oxide (Al ₂ O ₃ ), silicon oxide (SiO ₂ ), titanium oxide (TiO ₂ ), zinc oxide (ZnO), and tin oxide (SnO ₂ ). The haze, adhesion, water resistance and corrosion resistance were confirmed by the examples. For comparison, measurements were also performed for the case where no metal oxide particles were included and the case where no silane coupling agent was included.

[Test pieces]
A special modified acrylic two-component paint (made by Origin Electric Co., Ltd.) as a special primer for silver mirror reaction is prepared on the ABS plastic plastic material with the specified composition (main agent / curing agent / solvent), stirred well, and sprayed Painted. Thereafter, drying was performed at 80 ° C. for 60 minutes, and the film was immersed in a stannous chloride solution as a sensitization treatment for promoting silver deposition. Further, a silver nitrate ammonia solution and a solution containing a reducing organic compound were simultaneously applied to deposit silver on the surface of the special primer. After silver precipitation, it was washed with sufficient pure water and dried at 70 ° C. for 30 minutes to form a silver mirror film.

[Anti-rust paint]
Various metal oxide particles having an average particle size of 30 to 40 nm (a mixture of an acrylic resin containing amino groups (4.5% by weight) and a silane coupling agent having an epoxy group (1.0% by weight)) ( Al ₂ O ₃ , SiO ₂ , TiO ₂ , ZnO, SnO ₂ ) (0.5 to 16.5% by weight) was dispersed in an ester organic solvent to obtain a rust preventive paint. The anticorrosive paint was further diluted 5-fold with an alcoholic organic solvent (2-butoxyethanol) and spray-coated on the silver mirror film of the test piece. After coating, drying was performed at 70 ° C. for 30 minutes. The thickness of the coating film of the anticorrosive paint after drying was 70 to 700 nm. The predetermined solid content concentration of the rust preventive paint is 45% by weight of metal oxide particles, 45% by weight of acrylic resin, and 10% by weight of silane coupling agent. The weight of metal oxide particles contained in the coating film is calculated by pwc (%) = weight of metal oxide particles / (weight of metal oxide particles + weight of acrylic resin + weight of silane coupling agent) (pwc) %).

[Top coat film]
For the top coat film, a silicon acrylic two-component clear paint (manufactured by Origin Electric Co., Ltd.) was prepared with a specified formulation (main agent / curing agent / solvent), sufficiently stirred, and then spray-coated. After coating, it was cured and dried at 80 ° C. for 30 minutes, and then allowed to stand at 25 ° C. and 55% relative humidity for 7 days. The thickness of the top coat film was 25 ± 2 μm. Hereinafter, a plastic material including a silver mirror film, a rust-proof paint film and a top coat film is referred to as a plastic test piece. In addition, a test piece (hereinafter referred to as a magnesium alloy plate test piece) coated on a magnesium alloy plate at the same time as the previous coating was created, and a test piece in which only a coating film of anticorrosive paint was formed on an acrylic plate. (Hereinafter referred to as an acrylic plate test piece). The thickness of the anticorrosive paint film was also observed.

[Evaluation methods]
1) Transparency between the anticorrosion coating film and the top coating film was visually inspected using a magnesium alloy plate test piece.
2) About the cloudiness of the coating film of the anticorrosive coating, the light transmittance was measured with DEGRAL HAZE COMPUTER manufactured by Suga Test Instruments Co., Ltd. using an acrylic plate test piece.
3) About adhesiveness, it measured by the cross-cut method based on JISK5400 using the plastic test piece. Specifically, the coating film was cut into a grid pattern with a cutter (1 mm interval, 100 squares), the cellophane tape was brought into close contact, and then peeled off, and the coating mass peeled off from the article surface was counted. .
4) For water resistance, the plastic test piece was immersed in warm water at 40 ° C. for 240 hours, taken out from the warm water, removed the moisture on the surface of the coating, and allowed to stand until the surface temperature reached room temperature. Measurements similar to visual inspection and adhesion measurements were made.
5) As for corrosion resistance, a salt spray test for 240 hours in accordance with JIS Z 2371 was performed, the corrosion state of the silver mirror film surface was visually observed, and the degree of corrosion was expressed by the rating number (RN) described in JIS H 8679. . When the corrosion area ratio is 0.5% or less, it is obtained from the rating number standard chart. When it exceeds 0.5%, the relational expression RN between the corrosion area ratio (A%) and the rating number (RN). = 3 × (2-log ₁₀ A).
6) The thickness of the coating film of the anticorrosive paint was measured by observing the cross section of the acrylic plate test piece with a microtome and observing the cross section with a scanning electron microscope (SEM). When the coating film had irregularities, the thickness of the concave portion was taken as the thickness of the coating film.

[Visual inspection]
In FIG. 4, the measurement result of the visual inspection about the composition of a rust preventive coating material, transparency, and water resistance is shown collectively, changing a metal oxide particle variously. In any case, the thickness of the anticorrosive coating film was about 200 nm and the pwc was 45%.

According to visual inspection, the coating film was colorless and transparent except in the case of titanium oxide particles (TiO ₂ ). In the case of titanium oxide particles, the coating film of the rust preventive paint is cloudy, and the light transmittance measurement using an acrylic plate test piece is 80.3%, which is compared with the case of other metal oxide particles. The metal luster is somewhat impaired. In the case of tin oxide (SnO ₂ ), metallic luster was confirmed by visual inspection, but the light transmittance was 83.8%, which was slightly lower than in the case of other metal oxide particles. In the case of other metal oxide particles, that is, aluminum oxide (Al ₂ O ₃ ), silicon oxide (SiO ₂ ), and zinc oxide (ZnO), the light transmittance is the same value as when no metal oxide particles are included, 85 It was found that there was no effect on transparency. In addition, since the light transmittance of the used acrylic plate itself was 85.2%, in this example, in the case of aluminum oxide, silicon oxide, and zinc oxide, the coating film of the anticorrosive paint affects the appearance. It turned out not to give. Moreover, the result of the visual inspection after being immersed in warm water of 40 ° C. for 240 hours was not different from the initial stage. That is, it was confirmed to have water resistance.

[Adhesion, water resistance, corrosion resistance]
FIG. 5 shows the composition of the anti-corrosion paint, the adhesion of the anti-corrosion paint film, and the warm water at 40 ° C. when the metal oxide particles are variously changed as used in the appearance inspection shown in FIG. The measurement results for the adhesion (water resistance) of the anti-corrosion paint on the coating film after immersion for 240 hours and the visual observation (corrosion resistance) of the corrosion state of the silver mirror film surface after the salt spray test for 240 hours are shown. . In addition to the test piece used in the appearance inspection shown in FIG. 4, 4.5% by weight of aluminum oxide, 4.5% by weight of acrylic resin, and no silane coupling agent (that is, 0.0% by weight) In some cases, the measurement was also performed on a test piece in which the top coat was not acrylic-silicon (SA) but acrylic-urethane (SU).

  As a result of measurement of adhesion, the peel number was 0 out of 100 in any metal oxide particle, and the peel number was 0 out of 100 even without a silane coupling agent. However, when the top coat was made of acrylic-urethane rather than silicon-acrylic, peeling was observed at 45 out of 100 and the adhesion was significantly reduced. This is because the silicon-acrylic top coat contains a silane coupling agent as a curing agent, and this silane coupling agent diffuses from the anticorrosive paint film to the silver mirror film, and the anticorrosive paint becomes the silane coupling agent. On the other hand, it is considered that the acrylic-urethane top coating does not contain a silane coupling agent. That is, it was confirmed that the adhesion force was increased by the silane coupling agent, and sufficient adhesion force was obtained in any metal oxide particles.

  Also, the adhesion of the anticorrosive coating film after being immersed in warm water at 40 ° C. for 240 hours, that is, the measurement result of the water resistance is the same as the measurement result of the adhesion in any metal oxide particles. Even when no silane coupling agent was used, the number of peels was 0 out of 100, and when the top coat was made of acrylic-urethane, peeling was observed at 100 out of 100. That is, if it does not contain a silane coupling agent, the adhesive strength is weakened by moisture, but if it contains a silane coupling agent, the adhesive strength is not affected by moisture and it has sufficient water resistance. Was confirmed.

  In addition, in the visual observation of the corrosion state of the silver mirror film surface after the salt spray test for 240 hours, that is, the measurement result of the corrosion resistance, a difference in the rating number range of 6 to 0.9 and the type of metal oxide particles was observed. . A rating number of 6 means a corrosion area ratio of about 1%, a rating number of 0.9 means a corrosion area ratio of about 50%, and a rating number of 3 means a corrosion area ratio of 10%. %. That is, aluminum oxide particles had the highest corrosion resistance, followed by zinc oxide particles, and in the case of silicon oxide particles, titanium oxide particles, and tin oxide particles, the corrosion resistance was comparable. The rating number is equivalent to the case of silicon oxide particles, titanium oxide particles and tin oxide particles, and the case of not containing metal oxide particles (0.9), but does not contain metal oxide particles in appearance. In some cases, the metallic luster was lost due to fading of the silver mirror film, and the appearance discoloration such as darkening was remarkably observed. The antirust effect was confirmed.

FIG. 6 is a graph showing the rating number obtained by the above measurement in relation to the isoelectric point of the metal oxide. The “isoelectric point” is the pH when the acidic and basic charges are zero in the aqueous solution, that is, when the positive charge and the negative charge are balanced. The metal oxide is positively charged at a pH lower than the isoelectric point and negatively charged at a pH higher than the isoelectric point. Therefore, in the case of aluminum oxide particles and zinc oxide particles, the isoelectric point is 8 or more, and the surface of the metal oxide is −MOH ₂ ⁺ in a neutral aqueous solution (where M is a metal element) ). Therefore, when salt water (neutral aqueous solution) is sprayed on a coating film containing such a metal oxide, the surface of the metal oxide becomes -MOH ₂ ⁺ due to the water soaked in the coating film, and this soaks into the coating film together with water. It is considered that chlorine ions Cl ⁻ are trapped in the state of −MOH ₂ ⁺ + Cl ⁻ , preventing chlorine ions from reaching the surface of the silver mirror film, and preventing corrosion of the silver mirror film. On the other hand, silicon oxide, titanium oxide, and tin oxide, and the isoelectric point of 7 or less, the surface of the metal oxide in a neutral aqueous solution -MO ^- has become. Therefore, chlorine ions are unlikely to be captured on the surface of the metal oxide, and it is considered that the rust prevention effect is inferior to aluminum oxide and zinc oxide having an isoelectric point of 8 or more.

[Influence of coating thickness of rust preventive paint]
In the case of the aluminum oxide particles having the best corrosion resistance in FIG. 7, the light transmittance, adhesion, and warm water at 40 ° C. when the coating thickness of the anticorrosive paint is changed from 70 nm to 700 nm. The measurement results for the adhesion (water resistance) of the anti-corrosion paint on the coating film after immersion for 240 hours and the visual observation (corrosion resistance) of the corrosion state of the silver mirror film surface after the salt spray test for 240 hours are shown. . As is apparent from FIG. 7, even when the coating thickness of the anticorrosive paint was increased from 70 nm to 300 nm, no change was observed in the light transmittance. When the thickness was 700 nm, there was a slight decrease in the light transmittance. It can be seen. That is, it was confirmed that the light transmittance in the coating film of the anticorrosion paint using the aluminum oxide particles was sufficiently high. Regarding the adhesion and the adhesion in the water resistance test, even if the thickness of the coating film of the rust preventive paint was increased from 70 nm to 300 nm, neither the adhesion nor the adhesion in the water resistance test was observed, and 700 nm As a result, a decrease was observed in any of the adhesion properties. However, for the visual observation of the corrosion state of the silver mirror film surface after the salt spray test, that is, the corrosion resistance, if the coating thickness of the anticorrosive paint is increased, the rating number increases and the corrosion resistance is improved. confirmed.

[Influence of metal oxide particle content]
Subsequently, FIG. 8 shows the light transmittance, adhesion, and adhesion of the anticorrosive paint on the coating film after being immersed in warm water at 40 ° C. for 240 hours when the aluminum oxide content, ie, pwc is changed ( The measurement results for the visual observation (corrosion resistance) of the corrosion state of the silver mirror film surface after the salt spray test for 240 hours are shown together. As apparent from FIG. 8, in any case, there is almost no change in the light transmittance. When aluminum oxide particles having an average particle diameter of 30 to 40 nm are used, the amount of the aluminum oxide particles is determined by the light transmittance. It was confirmed that it does not affect Moreover, the adhesiveness accompanying the change of pwc and the change about the adhesiveness in a water resistance test were not seen, but it was confirmed that favorable adhesiveness is obtained also in any pwc. In addition, regarding the visual observation of the corrosion state of the silver mirror film surface after the salt spray test, that is, the corrosion resistance, it was found that when the amount of aluminum oxide particles was increased, the rating number also increased, that is, the corrosion resistance was improved.

  As described above, as confirmed in Examples, in the case of titanium oxide particles, although some white turbidity is observed, in the anticorrosive paint according to the present invention, the metal oxide particles having a particle diameter of 20 nm to 50 nm and Since it has an acrylic resin and a silane coupling agent, it was confirmed that it was excellent in transparency, adhesion and water resistance. Regarding corrosion resistance, it was confirmed that aluminum oxide particles were excellent and zinc oxide particles were next excellent. Moreover, unless the thickness of the coating film of the anticorrosive paint is extremely increased, the transparency, adhesion and water resistance are hardly affected, and it is confirmed that the corrosion resistance is improved when the thickness is increased. Furthermore, it was confirmed that the content of the metal oxide particles hardly affects the transparency, adhesion, and water resistance, and that the corrosion resistance is improved when the content is increased.

FIG. 2 is a partial cross-sectional view of a plastic article in which a silver mirror film is formed on an article made of plastic, and a rust-proof coating film and a top coating film are formed thereon. It is a flowchart explaining the formation method of a silver mirror film. It is a flowchart explaining the manufacturing method of the plastic articles which have metallic luster. It is a figure which summarizes the measurement result of the visual inspection about the composition of a rust preventive coating material, transparency, and water resistance, changing various metal oxide particles. The composition of the rust preventive paint, the adhesion of the rust preventive paint film, and the adhesion of the rust preventive paint after immersion in warm water at 40 ° C. for 240 hours when the metal oxide particles are changed variously (water resistance ) And the measurement results of visual observation (corrosion resistance) of the corrosion state of the silver mirror film surface after a 240 hour salt spray test. It is a graph showing the relationship between the isoelectric point of a metal oxide and a rating number. In the case of aluminum oxide particles, the light transmittance, adhesion, and adhesion of the anticorrosive coating on the coating after being immersed in warm water at 40 ° C. for 240 hours when the thickness of the anticorrosive coating is changed. It is a figure which shows collectively the measurement result about the visual observation (corrosion resistance) of the corrosion state of the silver mirror film surface after the salt spray test for 240 hours (water resistance). Light transmittance, adhesion, and adhesion of rust-preventive coating film after being immersed in warm water at 40 ° C. for 240 hours when water content (pwc) of aluminum oxide is changed, and 240 It is a figure which shows collectively the measurement result about the visual observation (corrosion resistance) of the corrosion state of the silver mirror film surface after the salt spray test of time.

Explanation of symbols

10 Plastic articles 12 Articles made of plastic (Coated articles)
14 Silver mirror film 16 Anticorrosive paint film 18 Top coat film

Claims (6)

Metal oxide particles having a particle size of 20 nm to 50 nm;
Acrylic resin;
A silane coupling agent;
Anti-rust paint. The metal oxide particles comprise aluminum oxide particles or zinc oxide particles;
The rust preventive paint according to claim 1. Articles made of plastic material;
A silver mirror film formed on the surface of the article;
A rust preventive paint film according to claim 1 or 2 formed on the silver mirror film;
Plastic article. Forming a silver mirror film on the article to be coated by silver mirror reaction;
And a step of applying the anticorrosive paint according to claim 1 over the silver mirror film;
A method for producing a rust-proof silver mirror film. And a step of applying a top coating on the film of the anticorrosion coating applied by the step of applying the anticorrosion coating;
A method for producing a rust-proof silver mirror film according to claim 4. Forming a plastic material into an article having a predetermined shape;
And a step of producing a rust-proof silver mirror film by the method for producing a rust-proof silver mirror film according to claim 4 or 5 on the surface of the article;
A method for producing plastic articles.

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