JP5491754B2 - Pre-coated aluminum plate - Google Patents

Description

  The present invention mainly relates to a precoated aluminum plate made of an aluminum plate, which is used for industrial electronic devices, consumer electronic devices, automobile electrical components and the like.

  Aluminum has various features such as low specific gravity and good thermal conductivity, and is therefore used in various applications. Since this aluminum is excellent in corrosion resistance in a natural environment, there are many cases in which surface treatment for preventing corrosion is not performed, but in recent years, surface treatment for the purpose of imparting functions has been increasingly performed. For example, in applications where lightness is required, such as notebook PCs, flat-screen TVs, and car stereos, the use of precoated aluminum plates made of aluminum plates and pre-coated with functional films (precoat films) is increasing. Yes. When this pre-coated aluminum plate is used, there is an advantage that the productivity and cost are superior to the after-coating method in which an aluminum plate that has not been surface-treated in advance is individually surface-treated after press forming.

  In addition, the cover of slim type optical disk drive devices mounted on notebook PCs, etc. (1) Lubricity (quick-drying press oil that does not require cleaning in order to reduce the manufacturing cost by omitting the step of cleaning the press oil) (2) Scratch resistance and fingerprint resistance (to improve appearance quality), (3) Conductivity (to ensure antistatic and grounding) Aim) is required. As an example of a pre-coated aluminum plate that satisfies these requirements, for example, in Patent Document 1, a predetermined corrosion-resistant film and a predetermined resin film are formed on at least one surface of an aluminum plate having a predetermined arithmetic average roughness Ra, An aluminum plate for electronic equipment that improves the conductivity by defining the surface resistance value and satisfies the other required performances is disclosed.

  In addition, the inner surface of the cover used in the slot-in type optical disk drive is directly rubbed with the disk when the optical disk is loaded and unloaded. Thus, among the optical disk drives, as an invention assuming application to a slot-in type optical disk drive, for example, in Patent Document 2, a soft bead having a predetermined hardness is added to a precoat film, and the film is cushioned. A pre-coated aluminum metal plate that prevents wrinkles on the surface of the optical disc by providing the same is disclosed.

  Incidentally, housings (covers, etc.) of consumer electronic devices such as optical disk drive devices assumed in Patent Document 1 and Patent Document 2 are formed by forming an aluminum plate into a box shape by bending 90 degrees. I came. The technology for producing box-type housings by bending is to use a coiled plate, continuous molding with progressive molds is possible, and continuous molding technology using quick-drying press oil has been established. Therefore, a cleaning process after press molding is unnecessary, and it can be said that the method is excellent in productivity. However, on the other hand, since a case manufactured by bending always has a gap at the corner of the side wall, the following problems arise when the case needs to be sealed.

  Examples of cases in which high sealing performance is required for the housing include, for example, automotive control electrical components installed in harsh environments such as engine rooms (control devices such as ECUs, batteries for hybrid vehicles and electric vehicles, inverters, etc. In these cases, if the airtightness inside the housing cannot be maintained, moisture, oils, dust and the like may enter the housing and cause a failure. Aluminum plate molded products are also used for lithium ion batteries and electrolytic capacitor cases. However, in applications where liquids such as electrolytes are placed inside, as in these cases, in order to prevent liquid leakage, However, the case is required to have high sealing performance. Further, even in consumer electronic devices used in a room such as a home, it is expected that the electromagnetic wave shielding property can be improved by enhancing the sealing property of the cover. As described above, in order to manufacture a case with high hermeticity, a method of forming a box-type case without a gap by drawing rather than bending is advantageous. FIG. 3A is a schematic diagram of a box-shaped housing by bending, and FIG. 3B is a schematic diagram of a box-shaped housing by drawing.

  Note that the inventions described in Patent Document 1 and Patent Document 2 are inventions that assume an optical disk drive as their application, and as described above, are considered to be inventions based on the premise of housing fabrication by bending. Therefore, when used for a drawing process in which a metal plate as a material is greatly deformed, there is a possibility that the film is peeled off or wrinkled.

Here, when applying a pre-coated aluminum plate to these cases, it is required that the pre-coated film not only follows the large deformation accompanying the drawing process, but also the pre-coated film. Examples of Patent Document 3 and Patent Document 4 are listed below as documents related to the invention assuming drawing.
As a pre-coated aluminum plate that assumes a large deformation of the pre-coated film associated with the drawing process, for example, Patent Document 3 discloses the gel fraction of the pre-coated film as the intermolecular cross-linked state of the thermosetting resin formed on the surface of the aluminum plate. When the value is compared before and after the heat treatment at 220 ° C., the gel fraction value after the heat treatment is continuously reduced from the value of the gel fraction before the heat treatment, Disclosed is a precoated aluminum plate that satisfies high drawability by controlling so that the decrease from the value of the gel fraction before the heat treatment when the heat treatment is performed for 10 minutes is less than 10%. Has been.

  As a technique other than the above-mentioned precoated aluminum material, a film laminated aluminum plate obtained by laminating a thermoplastic resin film excellent in workability is used in the case of an electrolytic capacitor. Since the film laminated aluminum plate has no cross-linked resin molecules constituting the film, the film can be greatly deformed and has advantageous properties for drawing. In addition, some of these have improved durability of cleaning chemicals with chlorinated solvents. For example, Patent Document 4 includes a thermoplastic resin film provided on the surface of an aluminum plate and a thermosetting resin coating layer provided on the surface of the thermoplastic resin film, thereby maintaining moldability. However, a resin-coated laminated aluminum plate for an electronic component case that prevents the discoloration of the resin coating layer has been disclosed. Further, it is described that a polyamide resin such as nylon or a saturated polyester resin such as PET is used as the thermoplastic resin film.

JP 2003-313684 A (paragraphs 0020-0050) Japanese Patent No. 4134237 (paragraphs 0024 to 0042) JP 2006-305841 A (paragraphs 0024 to 0051) Japanese Patent No. 4003915 (paragraphs 0017 to 0029)

However, the conventional techniques have the following problems.
The invention described in Patent Document 3 assumes drawing processing, and from the viewpoint of securing processing adhesion and heat discoloration at the time of drawing processing, a polyester system is desirable as a base resin. However, polyester films mainly composed of ester bonds are relatively easy to hydrolyze when compared with other resins, so there is no problem when used at home, but when used for outdoor or in-vehicle applications. Is inferior in durability under a high temperature and humidity atmosphere, and the reliability of the film is not sufficient.
Further, in the drawing process where the deformation amount of the aluminum plate is large, the continuous forming technique using the quick-drying press oil as described in the case of the bending process has not been sufficiently established. Therefore, many methods are still employed in which unnecessary pressing oil and abrasion powder are removed using a cleaning agent after molding using high-viscosity rust preventive oil or emulsion type wax. In such a method, it is not sufficient that the precoat film satisfies the moldability capable of following a large deformation, and problems such as dissolution, peeling, discoloration, and sticking of the film to the chemical used in the cleaning process. The durability of the film in the cleaning process is indispensable. Here, in the cleaning process, when performing a harsh cleaning method such as immersing in a boiling liquid of a chlorinated solvent such as trichlene, the technique described in Patent Document 3 dissolves, peels off the film of the molded article, Discoloration, sticking, etc. may occur, causing appearance defects.

  As described in Patent Document 4, a film laminate material made of a thermoplastic resin as a base resin and laminated on the surface of an aluminum plate uses a thermoplastic resin film. Naturally there is a limit. For example, when a polyamide-based thermoplastic resin typified by nylon is used as a base resin, it has good adhesion to an aluminum plate and excellent moldability, but in a high temperature environment, the base is heated in a relatively short time. There is a problem that the resin is easily yellowed or browned. Furthermore, when using a saturated polyester-based thermoplastic resin such as PET as the base resin, it has good adhesion to the aluminum plate, excellent moldability, and does not easily discolor the base resin even in high-temperature environments. However, since the base resin is easily hydrolyzed, it tends to be inferior in durability under a high-temperature and humid atmosphere.

  In addition, when a polyolefin resin typified by polyethylene or polypropylene is used as a base resin, the base resin is basically composed only of carbon and hydrogen and does not contain nitrogen or oxygen. Therefore, there is no origin of functional groups and chemical bonds such as hydroxyl groups, carboxyl groups, ester bonds, isocyanate groups, urethane bonds, amino groups, and amide bonds, and the adhesiveness to the aluminum plate is poor.

Therefore, it is a pre-coated aluminum plate that uses a thermosetting resin that has higher heat resistance and durability than the film laminate material, has good adhesion to the aluminum plate, exhibits excellent moldability, and can easily be used in high temperature environments. There is a demand for a precoated aluminum plate that does not undergo thermal discoloration and is excellent in durability under a high-temperature and humid atmosphere that is a concern in polyester-based coatings.
Also, in the process of washing and removing press oil and wear powder in the detergent after press molding, the precoat film can be dissolved, peeled off, and discolored even in the case of washing in a boiling chlorine detergent with high washing ability. Development of a pre-coated aluminum plate that can prevent surface abnormalities such as sticking and the like and has excellent durability of the film in the cleaning process is desired. Furthermore, in addition to the excellent durability of the coating film in the cleaning process, a precoated aluminum plate that has excellent formability in drawing and does not impair the beautiful gloss appearance of the aluminum plate is more desired.

  The present invention has been made in view of the above problems, and uses a thermosetting resin mainly composed of an epoxy resin excellent in durability under a high-temperature and humid atmosphere, and achieves both high moldability and heat discoloration, It aims at providing the precoat aluminum plate excellent also in chemical resistance.

A pre-coated aluminum plate according to the present invention (invention 1) is a pre-coated aluminum plate having a pre-coated film formed on the surface of the aluminum plate, and the pre-coated film is an epoxy resin and a non-yellowing type isocyanate-based curing. consists agent and thermosetting resins which are crosslinked between molecules, Ri gel fraction der less 92% 70% of the precoat film, the precoat film is in the thermosetting resin as the base resin include inorganic fine particles or fine particles is crosslinked organic fine particles, and surface roughness, arithmetic average roughness (Ra), characterized in der Rukoto than 0.25 [mu] m.

According to such a configuration, the precoat film is made of a thermosetting resin in which an epoxy resin is cross-linked between molecules, thereby improving durability under a high-temperature and humid atmosphere. The precoat film is composed of a thermosetting resin in which an epoxy resin and a non-yellowing type isocyanate curing agent are cross-linked between molecules, and the gel fraction of the precoat film is 70% or more and 92% or less. The epoxy resin is flexible, has high drawability, is excellent in chemical resistance, and can avoid discoloration in a heat test.
Further, according to such a configuration, by adding fine particles, the surface roughness (arithmetic average roughness (Ra)) of the precoat film is controlled, and the surface roughness Ra is 0.25 μm or more. The surface roughness of the precoat film becomes sufficiently large, and the adhesion between the films in the boiling chlorine-based cleaning agent is suppressed.

The precoated aluminum plate according to claim 2 is characterized in that the gel fraction of the precoated film is 70% or more and 85% or less.
According to such a configuration, the film can follow deep drawing with a larger amount of deformation by setting the gel fraction of the precoat film to 70% or more and 85% or less.

The precoated aluminum plate according to claim 3 is characterized in that the non-yellowing type isocyanate curing agent is a block type isocyanate compound.
According to such a configuration, when the paint (resin solution) is stored at room temperature by using a block-type isocyanate compound as the non-yellowing type isocyanate curing agent, the isocyanate curing agent and the epoxy resin Can be prevented from reacting and curing, and since the curing reaction proceeds quickly in the heating process in the painting line, the paint storage life can be greatly extended while maintaining rapid bake curability. .

The precoated aluminum plate according to claim 4 is characterized in that the fine particles are cross-linked spherical organic fine particles.
According to such a structure, the form of the convex part of a precoat film | membrane becomes smooth and the burden of the metal mold | die for press molding is reduced.

Moreover, the precoated aluminum plate according to claim 5 is characterized in that the surface roughness of the precoated film is an arithmetic average roughness (Ra) of 0.25 to 0.55 μm.
According to such a configuration, the irregular reflection of visible light on the surface of the precoat film is suppressed, and the precoat film is suppressed from being matted. Here, the matte state means that the gloss of the aluminum plate as the material is lost.

According to the invention of claim 1 of the present invention, it has excellent drawability (workability), is excellent in durability under a high temperature and humidity atmosphere, has both chemical resistance, and in a heat resistance test. A precoated aluminum plate that does not cause discoloration can be provided. As a result, it is possible to supply a light and highly airtight casing that is excellent in reliability even in outdoor or in-vehicle environments at low cost and with excellent productivity.
According to the invention of claim 2 of the present invention, it is possible to provide a precoated aluminum plate having a further (further) excellent drawability. As a result, the degree of freedom in designing the shape of the hermetically sealed housing is increased, and various shapes of the housing can be obtained, and the applicable range of the housing is expanded.
According to the invention which concerns on Claim 3 of this invention, the shelf life of the coating material which forms a precoat membrane | film | coat improves. As a result, the risk that the paint will expire and become unusable is reduced, leading to a total cost reduction. In addition, since industrial waste is reduced, it leads to environmental improvement.

According to the invention of claim 4 of the present invention, the film is not dissolved, peeled, discolored, stuck, or the like even when cleaning is performed in a severe boiling chlorine-based cleaning agent. It is possible to provide a precoated aluminum plate having excellent durability. Thereby, since the manufacturing process which can be selected spreads, the application field of a precoat aluminum plate spreads. In addition, since the basic chemical resistance of the coating is improved, not only the durability of the coating is improved in the cleaning process after press molding, but also the chemical resistance in the actual use environment is improved. Furthermore, the surface roughness Ra of the precoat film can be easily controlled, and a precoat film having a stable surface roughness Ra can be obtained.
According to the invention which concerns on Claim 5 of this invention, since the burden of the metal mold | die for press molding can be reduced, the lifetime of the metal mold | die for press molding can be improved.
According to the invention which concerns on Claim 6 of this invention, it becomes possible to provide the molded article of the beautiful gloss appearance which an aluminum plate has.

It is a fragmentary sectional view which shows typically the structure of the precoat aluminum plate which concerns on this invention. In an Example, it is a schematic diagram which shows the process of producing a bottomed cylindrical container by carrying out drawing processing and ironing of a test material. (A) is a schematic diagram which shows the box-type housing | casing by a bending process, (b) is a schematic diagram which shows the box-type housing | casing by a drawing process.

  Hereinafter, the best mode of the precoated aluminum plate according to the present invention will be specifically described with reference to the drawings as appropriate. FIG. 1 is a partial cross-sectional view schematically showing a configuration of a precoated aluminum plate according to the present invention.

≪Pre-coated aluminum plate≫
As shown in FIG. 1, a precoated aluminum plate 1 according to the present invention is a precoated aluminum plate 1 having a precoat film 3 formed on the (outermost) surface of an aluminum plate 2. The resin and the non-yellowing type isocyanate curing agent are composed of a thermosetting resin (base resin) 4 in which intermolecular crosslinking is performed, and the gel fraction is 70% or more and 92% or less. Although the fine particles 5 are not essential components (configuration) of the present invention, they are illustrated because they are preferably included in the precoat film 3. Here, the surface of the aluminum plate 2 means at least one surface of the aluminum plate 2. Each configuration will be described below.

<Aluminum plate>
The aluminum plate 2 referred to in the present invention is made of aluminum or an aluminum alloy, and the aluminum plate (aluminum plate or aluminum alloy plate) 2 used in the present invention is not particularly limited, and may be a product shape or a molding. The method can be selected based on the strength required at the time of use. In general, a non-heat-treatable aluminum plate, that is, a 1000 series industrial pure aluminum plate, a 3000 series Al—Mn alloy plate, and a 5000 series Al—Mg alloy plate can be preferably used. . In particular, when manufacturing (creating) a deep container-shaped casing accompanied by ironing, aluminum plates such as A1050, A1100, A3003, and A3004 defined in JIS H4000 are recommended. Moreover, when producing a comparatively shallow container-shaped housing | casing, aluminum plates, such as A5052 and A5182, prescribed | regulated to JISH4000 are recommended. Various types of tempering and plate thickness can be selected and used according to the purpose. Further, as will be described later, the aluminum plate 2 may be subjected to reactive base treatment, coating type base treatment, anodizing treatment, electrolytic etching treatment, degreasing treatment, and the like.

<Precoat film>
The precoat film 3 (film 3) comprises a thermosetting resin (base resin) 4 in which an epoxy resin (epoxy resin) and a non-yellowing type isocyanate curing agent are intermolecularly crosslinked, and the surface of the aluminum plate 2 Formed. The gel fraction of the precoat film 3 is 70% or more and 92% or less. In the base resin 4, a form containing fine particles 5 described later is desirable.

[Base resin]
The base resin (thermosetting resin) 4 is a main component of the precoat film 3, an epoxy resin (epoxy) as a main agent, and a non-yellowing type isocyanate curing agent (isocyanate (no yellowing) as a curing agent. )), And the intermolecular crosslinking reaction is performed so that the gel fraction is 70% or more and 92% or less. In addition, the mixing (blending) ratio of the epoxy resin and the non-yellowing type isocyanate curing agent is appropriately set depending on the type of the epoxy resin to be used.

  There is a film laminate material that uses a thermoplastic resin as a base resin as a material that does not undergo intermolecular crosslinking by a thermosetting reaction. However, as described in the prior art, a material that uses a thermoplastic resin as a base resin is heat resistant. A problem arises. There is also a pre-coating material that uses a polyester-based thermosetting resin as a thermosetting resin with excellent drawability (processing), but as described in the above-mentioned prior art, it is also durable in a high-temperature and humid atmosphere. There are challenges. However, when a thermosetting resin obtained by using an epoxy resin and a non-yellowing type isocyanate curing agent and having an intermolecular cross-linking reaction at a predetermined gel fraction is selected as the base resin 4, this resin is originally intermolecular. Since it has a functional group for crosslinking, the adhesiveness with the aluminum plate 2 is excellent. Moreover, since the crosslinking reaction is carried out while controlling the gel fraction, chemical resistance and heat resistance are improved while maintaining drawability. Moreover, since it does not have an ester group that is easily hydrolyzed, durability under a high-temperature and humid atmosphere is also improved.

  The epoxy resin (epoxy resin) used for the base resin 4 is a general term for resins having an epoxy group in which two carbon atoms and one oxygen atom are bonded in a triangular shape, and includes bisphenol A and epichlorohydrin. A typical example is a bisphenol A type epoxy resin having a repeating unit. In addition, bisphenol F type epoxy resin with reduced viscosity using bisphenol F instead of bisphenol A, a flame retardant epoxy resin obtained by reacting bisphenol A with bromine, a heat resistant epoxy resin based on a novolac resin, Alicyclic epoxy resins, etc. are known, and any epoxy resin of the present invention, including modified epoxy resins that have been chemically modified, may be used as long as it can be made into a paint. In view of the ease of coating, the balance between paint life and reactivity, price, safety, etc., it is preferable to use an epoxy resin having a basic skeleton of bisphenol A type or bisphenol F type or a modified product thereof.

  The glass transition temperature is one of the transition temperatures of the resin. Generally, a resin at a temperature higher than the glass transition temperature is a soft rubber, and a resin at a temperature lower than the glass transition temperature is a hard glass. Therefore, in order for the film 3 to follow a process with large deformation such as deep drawing or ironing, the glass transition temperature is theoretically required to be equal to or lower than the processing temperature. However, in reality, the macromolecular substances have a wide range of molecular weights, and the primary structure is not uniform, such as the occurrence of a branched structure in the molecule. I can't say that. Accordingly, the glass transition temperature is merely a representative value, and the transition gradually occurs in a temperature range having a certain width. In order to control (control) such a glass transition temperature, the above-described bisphenol A type or bisphenol F type is used as a basic skeleton, and a method of modifying the molecular structure by a chemical reaction is employed. Since the method is not particularly limited, a modified epoxy resin that has been modified can be used freely.

  Epoxy resins have a higher glass transition temperature than polyester resins and the like. This is advantageous for ensuring heat resistance and the like. The glass transition temperature of the epoxy resin has been reported up to about 200 ° C., but if it is used for a precoat material premised on press molding, a glass transition temperature of 120 ° C. or higher is not very realistic ( Processability is reduced, and the shape that can be formed is limited). In the epoxy resin used in the present invention, the glass transition temperature is desirably 80 ° C. or lower. In addition, the glass transition temperature here means what was measured by DSC method.

Since the epoxy resin has an epoxy group, the epoxy group can be thermoset by a chemical reaction. Further, bisphenol A type and bisphenol F type epoxy resins have a hydroxyl group in the molecule in addition to the epoxy group. Therefore, by adding a curing agent that reacts with these functional groups (hydroxyl groups), or by modifying the epoxy resin using a chemical reaction so that a component that acts like a curing agent is generated in the epoxy resin itself. By doing, an epoxy resin can be heat-hardened (thermosetting reaction), and a thermosetting resin can be obtained.
As epoxy resin curing agents, phenolic curing agents, amine (urea, melamine) curing agents including urea (urea) and melamine are generally used. In the present invention, no yellowing type is used. The isocyanate curing agent is used. When a phenolic curing agent is used, the phenolic hydroxyl group of the phenolic compound is known to react with an epoxy group, and it is easy to obtain a soft film having a large network in which the ends of the epoxy resin have reacted. As a result, a film having excellent moldability can be obtained, but there are problems that phenol is easily yellowed and chemical resistance is inferior. When a urea-based curing agent is used, yellowing such as phenol can be avoided, but the obtained film is hard and it is difficult to obtain excellent moldability. Moreover, about melamine type hardening | curing agent, hardening reactivity is very low. As a method of improving the reactivity of this melamine curing agent, it is possible to use an acid catalyst together, but depending on the conditions, the curing reactivity may become too high, or it may turn yellow. difficult.

  As the isocyanate curing agent used in the present invention, a non-yellowing type is used. Isocyanates (compounds) are classified into toluene diisocyanate (TDI), methylene bisphenyl diisocyanate (MDI), xylylene diisocyanate (XDI), isophorone diisocyanate (IPDI), hexamethylene diisocyanate (HDI) depending on the structure. being classified. The TDI system and the MDI system are easily yellowed (standard type), while the XDI system, the IPDI system, and the HDI system are hardly yellowed and are non-yellowing types. Polyisocyanates obtained by modifying these non-yellowing types with polyhydric alcohols are also included in the isocyanate curing agents that can be used in the present invention.

The non-yellowing type isocyanate curing agent is desirably a block type isocyanate compound. The block type here means that the active isocyanate group of the isocyanate compound is stabilized by a blocking agent such as an active hydrogen compound, and the reactivity is low at room temperature. This blocking isocyanate compound has reactivity due to dissociation of the blocking agent due to heating such as baking treatment, and regeneration of the active isocyanate group.
As blocking agents for blocked isocyanate groups, alcohols such as methanol, ethanol, n-propanol and tert-butanol, phenols such as phenol, m-cresol, isooctylphenol and resorcinol, ε-caprolactams, oximes, Examples include active methylene compounds such as acetylacetone, methyl ethyl ketone, and ethylene chlorohydrin, and sodium sulfite.

[Gel fraction of precoat film: 70% or more and 92% or less]
In the present invention, the gel fraction of the precoat film 3 is 70% or more and 92% or less. Here, when the precoat film 3 includes the fine particles 5 in the base resin 4, it is difficult to measure the gel fraction of the base resin 4 in a strict sense. Therefore, in the present invention, the gel fraction of the precoat film 3 is substituted and defined by this gel fraction.
When the gel fraction of the precoat film 3 is 70% or more, the crosslink density of the film 3 is increased, and the film 3 having excellent chemical resistance and heat resistance can be obtained. Moreover, since it can prevent that the film | membrane 3 hardens | cures too much if a gel fraction shall be 92% or less, the film | membrane 3 excellent in the drawability can be obtained. Furthermore, by setting the gel fraction of the film 3 to 85% or less, a further (further) excellent deep drawability can be obtained, which is more desirable. Thus, in order to make the gel fraction 70% or more and 92% or less, it is desirable that the baking temperature when baking the coating film is about 200 to 285 ° C. in terms of the material reaching temperature.

  The gel fraction can be measured by a method based on JIS K6796 (however, the extraction solvent is not xylene but 2-butanone). That is, the sample material of the precoated aluminum plate 1 is immersed in boiling 2-butanone (MEK) for 60 minutes, and the mass change of the precoated aluminum plate 1 before and after immersion is measured. Thereafter, the mass change of only the precoat film 3 is calculated by measuring the mass of the aluminum plate 2 in which only the precoat film 3 is completely dissolved, and it is assumed that the component that has not eluted into the MEK has undergone a crosslinking reaction. The ratio is calculated as a gel fraction.

[Fine particles]
The fine particles 5 are for controlling the surface roughness Ra of the precoat film 3 in a predetermined manner, and are desirably contained in the base resin 4 of the precoat film 3.
As a method of controlling the surface roughness without containing the fine particles 5 in the precoat film 3, a method of physically roughening the surface by blasting or the like after forming the precoat film, or a roll having unevenness A method of transferring the roughness of the roll by pressing the film onto the surface of the film is conceivable. However, the precoat film whose surface roughness Ra is adjusted by these methods has a problem that the unevenness of the film surface becomes smooth in the cleaning solvent, and the predetermined surface roughness in the precoat film cannot be maintained. As a result, the surface of the film becomes smooth, and the surfaces of the film easily adhere to each other in the boiling chlorine-based cleaning agent. However, in the precoat film 3 in which the fine particles 5 are contained in the base resin 4, the uneven shape of the film surface does not change before and after the solvent cleaning, and therefore, even in the cleaning process using the boiling chlorine-based cleaning agent, Sticking can be prevented.

  The type, form, size, amount of addition, etc. of the fine particles 5 are not particularly limited as long as the surface roughness Ra of the precoat film 3 can be controlled within a predetermined range by containing the fine particles 5 in the base resin 4. Good. Thereby, sticking of the films 3 in the boiling chlorine-based cleaning agent can be prevented. However, the type of the fine particles 5 is desirably inorganic fine particles or crosslinked organic fine particles. The other fine particles 5 include thermoplastic fine particles that are not cross-linked. However, when thermoplastic fine particles are used, the fine particles 5 are melted by the heat generated when the base resin 4 is subjected to a cross-linking reaction. Is not stable, and it is likely to be difficult to control the surface roughness Ra of the precoat film 3. In the case of inorganic fine particles or crosslinked organic fine particles, the fine particles 5 are not melted by the heat when the base resin 4 of the precoat film 3 is subjected to a crosslinking reaction, so that the precoat film 3 having a stable (uniform) surface roughness Ra is formed. Can be obtained.

  When inorganic fine particles are used as the fine particles 5, the convex portions of the precoat film 3 become hard. Therefore, in order to improve the lifetime of the press molding die, it is more desirable that the fine particles 5 are crosslinked organic fine particles. Furthermore, it can be said that when the shape of the fine particles 5 is spherical, the shape of the convex portion of the precoat film 3 when viewed microscopically becomes smooth, and therefore the influence on the mold life is small. Therefore, it is more desirable that the fine particles 5 are cross-linked spherical organic fine particles.

  As such crosslinked spherical organic fine particles, for example, crosslinked urethane fine particles, crosslinked acrylic fine particles, silicone fine particles, crosslinked polystyrene fine particles and the like can be suitably used. As an example of the crosslinked urethane fine particles, Daimic Seika Co., Ltd. Dimic beads (registered trademark) (Daiichi Seika), Art Pearl (registered trademark) (Negami Kogyo), etc. can be suitably used. Examples of Tofubo are Tuftic (registered trademark) AR (Toyobo), Riosphere (registered trademark) (Toyo Ink), Art Pearl (registered trademark) (Negami Kogyo), Techpolymer (registered trademark) (Sekisui Chemical Co., Ltd.) As an example of silicone fine particles, silicone powder (Shin-Etsu Chemical), Trefil (registered trademark) (Toray Dow Corning), etc. can be preferably used. Non-spherical organic fine particles include, for example, silicone rubber powder (X-52-875 (Shin-Etsu Silicone)), PTFE powder (KT-300M (Kitamura)), cellulose powder (KC Flock (registered trademark) (Nippon Paper Industries). Chemical)), flat polyethylene particles (Sumitomo Seika) and the like. Examples of the inorganic fine particles include nickel powder and talc powder, and examples of the non-crosslinked organic fine particles include thermoplastic urethane beads and polystyrene latex.

  Although there is no restriction | limiting in particular about the compounding ratio of the microparticles | fine-particles, If the ratio occupied to the precoat film 3 is less than 1 mass%, it is difficult to make surface roughness Ra 0.25 micrometer or more, and the boiling chlorine type | system | group cleaning agent was used. In the cleaning process, the surfaces of the precoat film 3 are easily adhered to each other. On the other hand, when it exceeds 50 mass%, it becomes difficult to fix the fine particles 5 to the base resin 4. Therefore, the blending ratio is desirably 1 to 50% by mass. In addition, it is more desirable that it is 3 to 30% by mass, and it is possible to suppress the appearance of the coating 3 from being matted, and considering that the beautiful gloss appearance of the aluminum plate 2 as a material is not hindered, More desirably, the content is 3 to 10% by mass.

  The particle diameter of the fine particles 5 is not particularly limited, but considering that the film thickness that can be applied with a general roll coater is approximately 1 to 20 μm, the precoat film 3 is less than 1 μm. Even when the target film thickness is relatively thin as 1 μm, it is difficult to make the surface roughness Ra 0.25 μm or more. On the other hand, when the average particle diameter exceeds 50 μm, it is difficult to fix the fine particles 5 to the base resin 4 even when the target film thickness is 20 μm and a relatively thick film thickness. Therefore, the average particle size is desirably 1 to 50 μm. In addition, it is desirable that the average particle diameter is 1 to 30 μm, considering that the appearance of the film 3 is suppressed to a matte state and considering that the beautiful gloss appearance of the aluminum plate 2 as a material is not disturbed. More desirably, the thickness is 2 to 10 μm. Here, the average particle diameter is an integrated volume 50% particle diameter measured with a laser diffraction particle size distribution measuring instrument or the like in a state where the fine particles 5 are dispersed in water.

[Surface roughness of precoat film]
The surface of the precoat film 3 is desirably formed so that the surface roughness is 0.25 μm or more in terms of arithmetic average roughness (Ra). In the cleaning process using the boiling chlorine-based cleaning agent, the surface roughness between the facing coatings 3 greatly affects the adhesion between the precoat coatings 3. That is, when the surface roughness Ra is less than 0.25 μm, the surface of the film 3 becomes smooth. Therefore, when the films 3 face each other and are washed with a boiling chlorine-based cleaning agent, a slight tackiness between the films 3 is slight. Begins to occur. Furthermore, when the surface roughness Ra is less than 0.15 μm, the surface of the precoat film 3 becomes smoother. Therefore, when the films 3 face each other and are washed with a boiling chlorine-based cleaning agent, the films 3 are strongly bonded to each other. It sticks. As described above, the adhesion between the coatings 3 in the cleaning process is greatly related to the smoothness of the surface of the precoat coating 3, and the larger the surface roughness Ra, the more the contact between the coating surfaces when viewed microscopically. Since the area is small, the sticking between the coatings 3 is suppressed.

  From the viewpoint of suppressing the sticking between the coatings 3, it is considered that the larger the surface roughness Ra is, the more desirable it is. Therefore, the upper limit value of the surface roughness Ra does not need to be specified. However, when the surface roughness Ra is increased, visible light is likely to be irregularly reflected on the surface of the coating 3, and the surface of the coating 3 has a matte appearance. The surface roughness Ra of the precoat film 3 is 0.55 μm or less in order to suppress the appearance of the film 3 from being matted and to not disturb the beautiful glossy appearance of the aluminum plate 2 as a material. It is desirable that The surface roughness Ra can be controlled by appropriately adjusting the particle diameter, blending ratio, film thickness and the like of the fine particles 5. The surface roughness of the precoat film 3 is measured using, for example, a surface roughness measuring device (Surfcoder SE-30D manufactured by Kosaka Laboratory Ltd.), and the direction of the probe perpendicular to the rolling direction of each aluminum plate 2. And the arithmetic average roughness (Ra) described in JIS B0601 can be measured.

[Others]
The precoat film 3 can contain colorants and additives that impart various functions without departing from the scope of the present invention.
In order to further improve the moldability, for example, a lubricant such as polyethylene wax, carnauba wax, microcrystalline wax, lanolin, Teflon (registered trademark) wax, silicone wax, graphite lubricant, molybdenum lubricant, etc. 1 type (s) or 2 or more types can be added. In addition, in order to provide conductivity for the purpose of securing the earth required for electronic equipment, etc., as the conductive fine particles, for example, metal fine particles including nickel fine particles, metal oxide fine particles, conductive carbon, graphite Etc. can be added singly or in combination of two or more. Furthermore, when it is desired to improve heat dissipation, one or more heat dissipation additives such as metal oxides such as carbon, graphite, and titanium oxide, and ceramic powder can be added. And when antifouling property is requested | required, you may add a fluorine-type compound and a silicone type compound.
Moreover, as described later, the thickness of the precoat film 3 is preferably 1 to 20 μm from the viewpoint of workability and productivity.

The best (embodiment) of the present invention has been described above, but the present invention is not limited to the above-described embodiment, and can be modified without departing from the scope of the present invention.
For example, a surface treatment film (not shown) may be provided on the surface of the aluminum plate 2 by surface treatment.

<Pretreatment>
The surface of the aluminum plate 2 is preferably subjected to a ground treatment in order to improve the adhesion with the precoat film 3. As a desirable base treatment, a conventionally known reactive type base coat and coating type base coat containing Cr, Zr or Ti can be used. That is, a phosphoric acid chromate film, a chromate chromate film, a zirconium phosphate film, a zirconium oxide film, a titanium phosphate film, a coating type chromate film, a coating type zirconium film, and the like can be used as appropriate. Organic-inorganic hybrid-type ground treatment coatings obtained by combining these coatings with organic components may also be used. In recent years, there has been a tendency to dislike hexavalent chromium from the trend of environmental measures, and phosphate chromate films that do not contain hexavalent chromium, zirconium phosphate films, zirconium oxide films, titanium phosphate films, coated zirconium films, etc. It is desirable to use it.

In the present invention, as the film thickness of the base treatment film, the amount of Cr, Zr or Ti contained in the base treatment film component to the aluminum plate 2 (metal Cr, metal Zr or metal Ti equivalent value) is, for example, Since the conventional fluorescent X-ray method can be used for comparatively simple and quantitative measurement, the quality control of the precoated aluminum plate 1 can be performed without hindering productivity. In addition, as an adhesion amount of a ground-treatment film | membrane, it is desirable that it is 10-50 mg / m < ² > in metal Cr, metal Zr, or metal Ti conversion value. If the adhesion amount is less than 10 mg / m ² , the entire surface of the aluminum plate 2 cannot be uniformly coated, and the corrosion resistance is lowered. Moreover, when it exceeds 50 mg / m < ² >, when the precoat aluminum plate 1 is shape | molded, it will become easy to produce a crack in the membrane | film | coat itself of a surface treatment.

  When productivity is not taken into consideration, a conventionally known process such as an anodizing process or electrolytic etching process can be performed on the surface of the aluminum plate 2. When these treatments are performed, fine irregularities are formed on the surface of the aluminum plate 2, so that the adhesion of the precoat film 3 is greatly improved.

  Furthermore, when the corrosion resistance is not required so much and a simple method is desired, a method in which only the surface of the aluminum plate 2 is degreased may be used. As a method of degreasing, conventionally known methods such as degreasing with an organic drug, degreasing with a surfactant drug, degreasing with an alkaline drug, degreasing with an acid drug, and the like can be used. However, in the case of organic chemicals and surfactant chemicals, the degreasing ability is slightly inferior, and therefore degreasing with an alkaline chemical or an acid chemical improves the productivity. The degreasing capacity of alkaline chemicals can be controlled by the main component, concentration, and processing temperature of the alkali used. However, if the degreasing capacity is strengthened, a lot of smut will be generated, and subsequent washing with water will not be performed sufficiently. On the contrary, the adhesion of the precoat film 3 may be lowered. In addition, when a variety containing a large amount of magnesium as an additive element is used for the aluminum plate 2, magnesium may remain on the surface and the adhesion of the precoat film 3 may be reduced with an alkaline chemical. Therefore, in this case, it is desirable to use or use an acid drug.

≪Pre-coated aluminum sheet manufacturing method≫
Next, an example of the manufacturing method of the precoat aluminum plate 1 is demonstrated.
The manufacturing method of the precoated aluminum plate 1 is not particularly limited, and the resin (epoxy resin) that is the base of the base resin 4, the curing agent (non-yellowing type isocyanate curing agent), and preferably the fine particles 5 are added. The coating material to be contained can be obtained by applying a crosslinking reaction by heating after coating on the aluminum plate 2 by a conventionally known method. In addition, in order to make the gel fraction in the film 3 70% or more and 92% or less, it is desirable that the baking temperature when baking the paint is about 200 to 285 ° C.

  Here, the coating can be applied by any means such as a bar coater, brush, roll coater, curtain flow coater, roller curtain coater, electrostatic coating machine, blade coater, die coater, etc. In particular, it is desirable to use a roll coater in which the coating amount is uniform and the operation is simple. When coating with a roll coater, the film thickness of the precoat film 3 is controlled by appropriately adjusting the conveyance speed of the aluminum plate 2, the rotation direction and rotation speed of the roll, the pressing pressure between the rolls (nip pressure), and the like. In a normal case, the thickness of the coating 3 that can be applied by one application operation is generally 1 to 20 μm. Therefore, the thickness of the precoat film 3 is desirably 1 to 20 μm in consideration of workability and productivity.

  Next, the precoated aluminum plate of the present invention will be specifically described by comparing an example satisfying the requirements of the present invention with a comparative example not satisfying the requirements of the present invention.

[First embodiment]
In the first embodiment, the pre-coated aluminum plate of the present invention has the essential purpose (essential performance) of the present invention, durability in a high-temperature wet environment (high-temperature wet durability), chemical resistance, heat discoloration resistance, aperture The moldability was examined.

In the examination of the pre-coated aluminum plate according to the present invention, the aluminum plate used as a material was a 0.3 mm thick material having an alloy number of A1100-H24. This was degreased with a weak alkaline degreasing agent, and then subjected to a phosphoric acid chromate treatment as a base treatment. The condition for the phosphoric acid chromate treatment was 20 mg / m ^{2 in} terms of chromium adhesion. The mechanical properties of the aluminum plate used were a tensile strength of 130 MPa, a proof stress of 120 MPa, and an elongation of 8%. Next, a coating material in which various main agents (resin system) shown in Table 1 and various curing agents are blended on one side of an aluminum plate subjected to a phosphoric acid chromate treatment is applied to a bar coater ( After coating with a bar coater, a precoat film having a changed gel fraction was formed by baking the paint so that the baking temperature was in the range of 150 to 285 ° C., and used as a test material. Moreover, the glass transition temperature shown in Table 1 is a glass transition temperature in each said resin system.

  About the test material manufactured as mentioned above, the gel fraction of the precoat film was measured.

(Measurement of gel fraction)
A test material (piece) obtained by cutting the test material into 10 cm × 10 cm was used, and the gel fraction of the film was measured. After the test material was dried at 80 ° C. for 60 minutes, the initial mass (a) was measured, and then the test material was immersed in boiled MEK for 60 minutes to elute uncrosslinked components, The remaining MEK in the film was dried at 150 ° C. for 60 minutes, and the mass (b) after extraction was measured. Finally, the film was completely dissolved in fuming nitric acid, and the mass (c) of the aluminum plate alone was measured. Here, (a)-(c) is the mass of the original precoat film only, and (b)-(c) can be regarded as the crosslinked film mass, so the gel fraction expressed by the following formula is It represents the degree of crosslinking.
(Gel fraction) = ((b)-(c) / (a)-(c)) × 100 (unit%)

  Next, each test material was examined for durability (high temperature wet durability), chemical resistance, heat discoloration, and drawability, which are essential objects of the present invention.

(High temperature wet (environmental) durability)
A flat plate test material cut out from the test material was used and left in a constant temperature and humidity chamber set to a temperature of 85 ° C. and a humidity of 85% RH for 1000 hours, and then the appearance of the film was visually confirmed. As a result, a film having no abnormalities was evaluated as good (◯), and a film having abnormal appearance such as discoloration, peeling, swelling, and cracking was defined as an abnormal appearance (×).

(chemical resistance)
A flat plate test material cut out from the test material was used, immersed in cyclic ester γ-butyllactone at room temperature for 10 minutes, and the appearance of the film was visually confirmed. As a result, a film having no abnormalities was evaluated as good (◯), and a film having abnormal appearance such as discoloration, peeling, swelling, and cracking was defined as an abnormal appearance (×).

(Heat-resistant discoloration)
A flat test material cut out from the test material was used and left in a box-type heating tank set at a temperature of 270 ° C. for 1 minute, and then the appearance of the film was visually confirmed. As a result, a film having no abnormalities was evaluated as good (◯), and a film having abnormal appearance such as discoloration, peeling, swelling, and cracking was defined as an abnormal appearance (×).

(Drawing formability)
FIG. 2 is a schematic diagram showing a process for producing a bottomed cylindrical container by drawing and ironing a test material. The drawability of the test material was examined by the process shown in FIG. First, after blanking a cylindrical blank, drawing was performed. Next, a 12 mmφ × 15 mmL cylindrical drawn product (intermediate molded product) was obtained by redrawing. The result of evaluating the film state of the intermediate molded product obtained at this time was defined as shallow drawability in Table 1. Next, the intermediate molded product was ironed so that the reduction rate of the thickness of the cylindrical side wall portion was 20%, trimmed, and processed into a final 10 mmφ × 20 mmL cylindrical container shape to obtain the final molded product. . The result of evaluating the film state of the final molded product obtained at this time was defined as the deep drawability in Table 1. The press oil used was an aqueous emulsion wax mainly composed of a fatty acid ester and a surfactant. The processing was performed at room temperature (35 ° C.).

  For the evaluation of the film state, the shallow drawability, which is an essential performance of the present invention, is that when the precoat film is not peeled off from the aluminum plate, the shallow drawability is good (O), and when the peel is peeled off, the shallow drawability is formed. Judgment was poor (×). In addition, only the specimens that had good shallow drawability (O) were confirmed to have the desired deep drawing formability. As a result, the precoat film was not peeled off from the aluminum plate and the deep drawability was good. In the case where it was present, the moldability was particularly good (◎), and when it was peeled off, it was regarded as defective (Δ).

  Table 1 shows the results of durability (high temperature wet durability), chemical resistance, heat discoloration resistance, and drawability in a high temperature wet environment. In addition, the underline in Table 1 indicates that the requirements defined in the present invention are not satisfied.

(High temperature wet (environmental) durability)
As shown in Table 1, a polyester resin was used as the resin system of the base resin. About 17-22, abnormality, such as whitening, a crack, and a blister, generate | occur | produced in the film | membrane external appearance. Among the test materials using an epoxy resin as the resin system of the base resin, No. 1 using a melamine-based curing agent as the curing agent. In No. 10, the coating melted and the appearance was abnormal. In addition, this No. No. 10 had a gel fraction of 0, and the epoxy resin and the melamine meter curing agent did not react at all. Each of the test materials other than the above seven types had good durability in a high temperature and humid environment.
From the above, in order to ensure durability in a high-temperature and humid environment, the main agent (resin system) used for the base resin needs to be an epoxy resin. Moreover, since it is necessary to react to some extent with a hardening | curing agent, a melamine type hardening | curing agent is not suitable as a hardening | curing agent.

(chemical resistance)
As shown in Table 1, the gel fraction of the base resin was less than 70%, No. As for 5, 7, 10, 11, 13, 15, 17, 19, and 21, all abnormalities such as whitening and dissolution occurred in the appearance of the film. Further, among the test materials having a gel fraction of 70% or more, No. 1 in which an epoxy resin and a phenolic curing agent were reacted. In No. 14, whitening occurred in the appearance of the film. Each of the test materials other than the above 10 types had good chemical resistance.
From the above, in order to ensure chemical resistance, the gel fraction of the film (base resin) needs to satisfy 70% or more. Also, phenolic curing agents are not suitable as curing agents.

(Heat-resistant discoloration)
As shown in Table 1, a phenolic curing agent was used as the curing agent. Nos. 13 and 14 and a standard type isocyanate curing agent that is not a non-yellowing type were used as curing agents. For No. 9, yellowing of the film was observed. Each of the sample materials other than the above three types had good heat discoloration.
From the above, it is important to select a curing agent in order to ensure heat discoloration, and a phenolic curing agent is not suitable, and when the curing agent is an isocyanate curing agent, no yellowing occurs. It is necessary to select the type.

(Drawing formability)
As shown in Table 1, in each test material in which an epoxy resin and an isocyanate-based curing agent (non-yellowing) are combined, the gel fraction exceeds 92%. For 6 and 8, film peeling occurred. In addition, no. For 11 and 12, film peeling occurred. In addition, the acrylic modified self-processed epoxy resin also has a high gel fraction. For 16, peeling of the film occurred. Each of the test materials other than the above five types had good shallow drawability.
From the above, the drawability (shallow drawability) is affected by the type (combination) of the main resin (system) and the curing agent, and the crosslinking reaction between the main agent (resin system) and the curing agent. It turns out that the influence of the gel fraction which shows a grade is also large. In particular, when the main agent (resin type) is an epoxy resin and the curing agent is an isocyanate type curing agent (no yellowing), it is important that the gel fraction is 92% or less. Also, urea curing agents are not suitable as the curing agent.

Next, the deep drawability (working) property was confirmed about each test material with favorable shallow drawability. As shown in Table 1, with respect to each test material in which an epoxy resin and an isocyanate curing agent (non-yellowing) were combined, the gel fraction exceeded 85%. In 2 and 4, the film peeled off during deep drawing (test). Also, acrylic modified self-crosslinking epoxy resin No. 15 and No. 15 using polyester resin. No. 22 was peeled off in the deep drawing test. As a result, it was No. which combined the epoxy resin and the isocyanate curing agent that satisfied the deep drawability. Nos. 1, 3, 5, 7, and 9 were combined with an epoxy resin and a melamine curing agent. No. 10, a combination of epoxy resin and phenolic curing agent. No. 13 and No. 14 using polyester resin. There were a total of 13 types of 5 types of 17-21.
In particular, when the main agent (resin) is an epoxy resin and the curing agent is an isocyanate curing agent (no yellowing), excellent deep drawability is obtained when the gel fraction is 85% or less. I understood it.

(Summary)
As shown in Table 1, those that satisfy all four essential performances of durability under high-temperature and humid environments (high-temperature wet durability), chemical resistance, heat discoloration resistance, and drawability (shallow drawability) , No. There were four types of 1-4.
Therefore, as a constitution of the precoat film of the precoat aluminum plate, the epoxy resin and the non-yellowing type isocyanate curing agent are combined and reacted so that the gel fraction becomes 70% or more and 92% or less. Then it turned out to be essential.
Further, No. 1 which satisfies the deep drawing formability, which is a desirable performance. 1 and No. The composition of the pre-coated aluminum plate is a combination of an epoxy resin and a non-yellowing type isocyanate curing agent, and reacts so that the gel fraction is 70% or more and 85% or less. It has been found desirable in the present invention.

[Second Embodiment]
In the second example, the paint life, which is a desirable object of the present invention, was examined for a paint containing an epoxy resin and a non-yellowing type isocyanate curing agent used when producing the precoated aluminum plate in the present invention. In addition, since the paint life is only a desirable characteristic for the present invention, even if these characteristics are not satisfied, those satisfying the results of the first embodiment can achieve the minimum object of the present invention. It is.

Mixing block type isocyanate curing agent or non-blocking type isocyanate curing agent with commercially available bisphenol A type or bisphenol F type epoxy resin (including modified epoxy resin), diluting solvent for viscosity adjustment As a sample material, a paint was prepared by mixing toluene.
The mixing ratio of the epoxy resin and the isocyanate curing agent was fixed at a ratio of 5: 1 in terms of solid content weight. The viscosity adjusting diluent was adjusted so that the initial viscosity immediately after the bath was # 4 Ford cup viscosity of 100 seconds (within ± 5 seconds).

(Paint life)
The test material paint thus constructed (adjusted) was placed in an airtight container and stored at room temperature for 7 days and 3 months, and then the viscosity was examined again to determine the paint life (paint life). Here, if the paint viscosity (Ford Cup) was within 150 seconds, it was determined that there was a lifetime.

  Table 2 shows the results for paint life. In addition, the underline in Table 2 indicates that the requirements defined in the present invention are not satisfied.

(Paint life)
As shown in Table 2, sample No. using a non-blocking type as the isocyanate curing agent. In 1, 3, 5, 7, and 9, all were solidified so that the viscosity of the paint could not be measured after 7 days, and the paint life was not sufficient. On the other hand, the test material No. using a block type isocyanate curing agent. 2, 4, 6, 8, and 10 all showed a slight increase (in seconds) at the stage after 3 months, and it was found to be reusable.

[Third embodiment]
In the third example, the durability of the precoated aluminum plate was investigated in order to investigate a more desirable form of the precoated aluminum plate in the present invention. The durability of the cleaning process is only a desirable characteristic for the present invention. Therefore, even if these characteristics are not satisfied, those satisfying the results of the first embodiment are the minimum object of the present invention. To reach.

The type, quality, mechanical properties of the aluminum plate used as the material, the pretreatment method and the conditions before coating are the same as in the first embodiment. A coating containing various fine particles (particle type, particle diameter μm) shown in Table 3 on a base resin made of an epoxy resin having a glass transition temperature of 77 ° C. and a non-yellowing type isocyanate curing agent on this aluminum plate was dried. After coating with a bar coater so as to be 6 μm, a precoat film was formed by baking so that the gel fraction was 80 ± 5%, and used as a test material.
In addition, No. 11 and no. No. 13 is a test material not containing fine particles. No. 13, after the bar coater coating and baking were completed, a stainless steel surface plate with a surface roughness Ra of about 0.5 μm was layered on the coated surface, and lightly sandwiched with a hot press heated at 40 ° C. for 10 minutes. The surface roughness of the board was transferred.
In addition, for the fine particles shown in Table 3, crosslinked acrylic (beads) and crosslinked urethane (beads) are crosslinked organic fine particles, nickel powder and talc powder are inorganic fine particles, and thermoplastic urethane (beads) are uncrosslinked organic fine particles. is there. The blending ratio was the mass% of the fine particles in the mass of the dry precoat film including the base resin and the fine particles.

  About the test material manufactured as mentioned above, the gel fraction and surface roughness Ra of the precoat film were measured. The method for measuring the gel fraction was the same as in the first example.

(Measurement of surface roughness Ra)
As for the surface roughness of the precoat film, a surface roughness measuring device (Surfcoder SE-30D manufactured by Kosaka Laboratory Co., Ltd.) was used, and the probe was scanned in a direction perpendicular to the rolling direction of each aluminum plate, and JIS B0601. The arithmetic average roughness (Ra) described in 1 was measured.

  Next, the test material was examined for film durability (cleaning process durability) at the time of boiling trichrane cleaning, which is a desirable object of the present invention, and other appearance properties.

(Washing process durability)
Trichrene was used as a chlorine-based cleaning agent and boiled. The coated surfaces of each test material were sandwiched between clips so as to face each other, immersed in the boiling trichrene for 10 minutes, and then taken out to confirm the appearance. A film having no surface abnormality such as dissolution, peeling, discoloration, and adhesion between films was judged to be defective (x) if it had good cleaning process durability (◯) and surface abnormality (such as adhesion).

(Appearance properties)
The appearance of the precoat film after bar coating and baking was visually observed. When the matte state, unevenness, yellow discoloration, etc. did not occur, the appearance properties were judged as good (◯). Moreover, it was judged that the appearance property was slightly inferior (x) when any of these occurred.

  Table 3 shows the results of cleaning process durability and appearance properties. In addition, the underline in Table 3 indicates that the requirements defined in the present invention are not satisfied.

(Washing process durability)
As shown in Table 3, no. In Nos. 1 to 10, since the surface roughness Ra was set to 0.25 μm or more by adding fine particles to the film, the cleaning process durability was good.
On the other hand, no. No. 11 contained no fine particles, and the surface roughness did not satisfy the scope of the present invention, so that the films were stuck together, and the durability of the cleaning process was poor. No. In No. 12, since the surface roughness did not satisfy the range of the present invention, the films were stuck to each other, and the durability of the cleaning process was poor. No. No. 13, although the surface roughness satisfies the scope of the present invention before immersion in boiling trichrene, since it does not contain fine particles, the unevenness of the coating surface becomes smooth during immersion in boiling trichrene, and the coatings stick to each other. occured.

(Appearance properties)
No. with good washing process durability. Nos. 1 to 10 are organic fine particles in which the fine particles are not crosslinked. No. 8 had a non-uniform appearance (non-uniform appearance) because the fine particles melted in the baking process after bar coater coating. In addition, this No. 8 and no. In the five types 2, 5, 7, and 10, the surface roughness Ra exceeded 0.55 μm, so the matteness of the film was strong (matte) and the luster of the aluminum material was impaired.

  Although no clear data has been obtained at this time, when inorganic fine particles are used as the fine particles, the convex portions of the precoat film become hard, and it is sufficiently expected to reduce the life of the press molding die. Similarly, when the particle shape is spherical, the shape of the convex portion of the precoat film when viewed microscopically becomes smoother, so there is no irrationality in considering that the influence on the mold life is small.

  The precoated aluminum plate according to the present invention has been described in detail with reference to the best mode and examples, but the gist of the present invention is not limited to the above-described contents, and the scope of the right is claimed. Must be interpreted based on the description. Needless to say, the contents of the present invention can be modified and changed based on the above description.

1 Pre-coated aluminum plate 2 Aluminum plate 3 Pre-coated film 4 Base resin (thermosetting resin)
5 Fine particles

Claims (5)

A precoated aluminum plate having a precoated film formed on the surface of the aluminum plate,
The precoat film is composed of a thermosetting resin in which an epoxy resin and a non-yellowing type isocyanate curing agent are intermolecularly crosslinked,
The gel fraction of the precoat film is state, and are less 92% 70%
The precoat film contains inorganic fine particles or fine particles which are crosslinked organic fine particles in the thermosetting resin which is a base resin, and the surface roughness is an arithmetic average roughness (Ra) of 0. precoated aluminum plate, wherein the Ru der least 25 [mu] m.   The precoated aluminum sheet according to claim 1, wherein the gel fraction of the precoat film is 70% or more and 85% or less.   The precoated aluminum plate according to claim 1 or 2, wherein the non-yellowing type isocyanate curing agent is a block type isocyanate compound. The precoated aluminum plate according to any one of claims 1 to 3, wherein the fine particles are cross-linked spherical organic fine particles. 5. The precoated aluminum plate according to claim 1, wherein the surface roughness of the precoat film is an arithmetic average roughness (Ra) of 0.25 to 0.55 μm. .

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