JP2014188766A - Precoated aluminum plate and method for producing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a precoated aluminum plate excellent in flaw resistance and moldability which is to be used for an external plate material such as home electrical appliances and components mounted on an automobile or a structural component.SOLUTION: There is provided a precoated aluminum plate whose surface is coated with a hard film having a film thickness of 0.2 to 10 μm, wherein the hard film is composed of a resin which contains 30 atom% or more and 50 atom% or less of C, 10 atom% or more and less than 30 atom% of each N, Si and O and in the resin, the content (atom%) of Si is 0.8 times or more and 1.2 times or less of the content of O. Such a precoated aluminum plate is produced by coating a coating material containing C, N, Si and O on an aluminum plate, followed by baking treatment at 210 to 280°C to form a hard film.

Description

  The present invention relates to an aluminum plate and an aluminum alloy plate applied to an outer plate material and a structural member such as household electrical appliances and automobile-mounted components, and a coating having excellent scratch resistance and formability is applied to the surface of the aluminum plate. This relates to a precoated aluminum plate provided by

  Aluminum plates and aluminum alloy plates applied to outer plate materials and structural members such as household electrical appliances and automotive parts, etc. have corrosion resistance, favorable appearance and scratch resistance to retain them, and others that correspond to applications In order to impart the above characteristics to the surface, a pre-coated plate having a resin film formed on the surface may be applied.

  As such a pre-coated plate imparted with scratch resistance, a technique is disclosed in which an inorganic material such as silica or resin beads is added to a resin material to form a film imparted with scratch resistance on a metal plate such as aluminum. (For example, Patent Documents 1 to 3). In addition, a coating containing a polymer having a specific bond and functional group and a blocked polyisocyanate is applied to a metal plate, and cured by irradiating with active energy such as ultraviolet rays or γ-rays. A manufacturing technique is disclosed (for example, Patent Document 4).

Japanese Patent No. 3106498 Japanese Patent No. 3818016 Japanese Patent No. 4067368 Japanese Patent Laid-Open No. 6-23319

  However, the resin film described in Patent Documents 1 and 2, to which an inorganic material or an aggregate such as glass is added, has improved hardness, but when it is slid repeatedly, the inorganic material that has been scraped off from the film has abrasion wear. Since it occurs and promotes wrinkling, sufficient wrinkle resistance cannot be obtained. Further, if the amount of the inorganic substance added is large, the inorganic substance in the film and the mold are rubbed by the drawing and the film is peeled off, and sufficient workability cannot be obtained for the pre-coated plate. The resin film to which the resin beads described in Patent Document 3 are added does not improve the hardness of the resin film itself as a binder of the resin beads, so that the scratch resistance is insufficient, and the resin film Depending on the size and type of the beads, the transparency is low and the surface is satin, and it is difficult to use for a member that requires glossiness or transparency that reflects the color tone of the metal plate as the base. The method for producing a coated metal processed product described in Patent Document 4 requires a step of irradiating active energy such as γ-rays, and after forming and processing the coated metal plate irradiated with active energy, it is applied by baking. Since the film is secondarily cured, the production is not easy and the productivity is poor.

  The present invention has been made in view of the above-mentioned problems, and is suitable for outer plate materials and structural members such as household electrical appliances and automobile-mounted parts, particularly those requiring gloss and transparency in appearance. An object of the present invention is to provide a pre-coated aluminum plate that is excellent in scratching and formability and easy to manufacture.

  As a result of intensive studies to solve the above problems, the present inventors have optimized the ratio of the resin component, particularly silicon and oxygen, to improve the hardness of the resin itself, and to improve lubricity Furthermore, the inventors have conceived of improving moldability by improving flexibility.

  That is, the precoated aluminum plate according to the present invention is formed by forming a hard film having a film thickness of 0.2 μm or more and 10 μm or less on one surface or both surfaces of the aluminum plate, and the hard film has a C content of 30 atomic% to 50 atomic%. Hereinafter, it is made of a resin containing N, Si, and O in a range of 10 atomic percent or more and less than 30 atomic percent, and the Si content is 0.8 times or more and 1.2 times or less that of O (atomic percent). It is characterized by being.

  In this way, since it is formed of a resin that regulates the concentration of C, N, Si, O and the ratio of Si and O, it becomes a film having appropriate hardness, flexibility, and lubricity. It is difficult to stick and moldability is obtained.

Furthermore, in the precoated aluminum plate according to the present invention, it is preferable that the hard coating has an absorption peak of an infrared absorption spectrum in a wave number range of 2100 to 2300 cm ⁻¹ . Thus, when the hard film has an absorption peak showing a C, C triple bond or a C, N triple bond, the film is excellent in toughness, and particularly high moldability is obtained.

  Moreover, the manufacturing method of the precoat aluminum plate which concerns on this invention is a method of manufacturing the said precoat aluminum plate, Comprising: The application | coating process of apply | coating the coating material containing C, N, Si, and O on the single side | surface or both surfaces of an aluminum plate, And a baking step of baking the applied paint at 210 ° C. or higher and 280 ° C. or lower to form a hard film.

  In this way, by applying a paint to an aluminum plate and baking it, the paint is dried and cured, and a precoated aluminum plate whose surface is coated with a hard film can be easily produced. Furthermore, the paint contains C, N, Si, and O, and the baking temperature is controlled within a predetermined range, so that it becomes a hard film having lubricity and moderate hardness, and is resistant to scratching and formability. An excellent precoated aluminum plate can be obtained.

  According to the precoated aluminum plate of the present invention, since it has excellent scratch resistance and formability, it can be applied to outer plate materials and structural members such as household electrical appliances and automobile-mounted parts, and in particular, the appearance is glossy and transparent. Suitable for what is required. Moreover, according to the manufacturing method of the precoat aluminum plate which concerns on this invention, it can manufacture with sufficient productivity by application | coating and a baking process.

  The precoated aluminum plate according to the present invention is a plate material that is cut and molded into a desired shape to be used as an outer plate material or a structural member such as a household electric product or a car-mounted component. Hereinafter, the form for implement | achieving the precoat aluminum plate which concerns on this invention is demonstrated.

[Pre-coated aluminum plate]
The precoated aluminum plate according to the present invention is obtained by coating the surface of an aluminum plate made of aluminum or an aluminum alloy with a hard film made of resin. In the precoated aluminum plate of the present invention, the hard coating may be formed on one side or both sides.
Below, each element which comprises the precoat aluminum plate which concerns on this invention is demonstrated.

(Aluminum plate)
The aluminum plate is a base material for the pre-coated aluminum plate, and 1000 series industrial pure aluminum, 3000 series Al—Mn based alloy, 5000 series Al—Mg based alloy can be applied and may be selected depending on the application. In particular, when drawing or ironing is performed, A1050, A1100, A3003, and A3004 defined in JIS H4000 are recommended. Also, A5052 and A5182 are recommended for use in applications requiring high strength. There is no restriction | limiting in particular about tempering and board thickness, It can select according to a use and the objective.

The aluminum plate is preferably subjected to a ground treatment on the surface, and a ground treatment layer is formed between the aluminum plate and the hard coating. By the ground treatment layer, the adhesion between the aluminum plate and the hard coating is improved, and the corrosion resistance of the aluminum plate is improved. As the ground treatment layer, a film containing at least one of conventionally known Cr, Zr, and Ti can be applied. For example, a phosphate 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. Moreover, you may make these films | membranes contain an organic component as needed. From the viewpoint of environmental considerations in recent years, it is desirable to use a phosphate chromate film that does not contain hexavalent chromium, a zirconium phosphate film, a zirconium oxide film, a titanium phosphate film, a coating-type zirconium film, or the like. The thickness of the ground treatment layer is preferably about 10 to 50 mg / m ^{2 in} terms of the amount of Cr, Zr, Ti deposited on the aluminum plate (Cr, Zr, Ti converted value). If the adhesion amount is less than 10 mg / m ² , the entire surface of the aluminum plate cannot be uniformly coated, and the effect cannot be obtained sufficiently. On the other hand, when the adhesion amount exceeds 50 mg / m ² , cracks are likely to occur in the base treatment layer itself. The Cr, Zr, Ti converted value can be measured relatively easily and quantitatively by, for example, the fluorescent X-ray method. Therefore, quality control of the aluminum plate can be performed without hindering productivity.

(Hard coating)
In the precoated aluminum plate, the hard coating is provided for imparting surface scratch resistance by its hardness and for imparting formability by flexibility and lubricity. The hard coating is formed with a film thickness of 0.2 μm or more and 10 μm or less, and is made of a resin containing a predetermined amount of carbon (C), nitrogen (N), silicon (Si), and oxygen (O).

  In the pre-coated aluminum plate according to the present invention, in order to obtain sufficient scratch resistance, the hard film has a pencil hardness measured according to JIS K5600-5-4 of 4H or more by scratch determination. Is desirable. Such hardness of the hard coating can be obtained by controlling the components of the resin forming the hard coating as described later.

(Film thickness: 0.2 μm or more and 10 μm)
The film thickness of the hard coating is 0.2 μm or more and 10 μm or less. When the film thickness is less than 0.2 μm, the effect of scratch resistance cannot be sufficiently obtained in the precoated aluminum plate. On the other hand, even if the film thickness exceeds 10 μm, further improvement in the effect is difficult to obtain, and cracks are likely to occur depending on the hardness of the hard coating. Moreover, since the hard film can be continuously formed on the coiled aluminum plate by using the roll coater by setting the film thickness within the above range, it is excellent in productivity and desirable in terms of cost. When the film thickness exceeds 10 μm, the liftability of the paint by the pick-up roll of the roll coater is insufficient and the variation in film thickness becomes remarkably large. On the contrary, if the film thickness is less than 0.2 μm, it is necessary to increase the pressure between the pickup roll and the applicator roll, and the roll is likely to be worn.

The hard coating contains C in a range of 30 atomic% to 50 atomic%, N, Si, and O in a range of 10 atomic% to less than 30 atomic%, respectively, and Si is 0.8 times to 1.2 times that of O. It consists of resin containing with the following content rate (atomic%). Further, the hard coating preferably has an absorption peak of an infrared absorption spectrum in the range of wave numbers 2100 to 2300 cm ⁻¹ . Such a hard film is formed of a silicone resin, a modified silicone resin, or a silicate resin, and is obtained by applying a resin coating material prepared by mixing resin materials onto an aluminum plate and baking it as described later. It is done.

(C: 30 atomic% to 50 atomic%)
C (carbon) is a main component of a resin that forms a hard film, and when it is contained in a large amount, the resin is softened while elongation is improved. Further, C is a component that imparts lubricity to the resin. When the C content is less than 30 atomic%, the hard film becomes excessively hard, and defects such as peeling or cracking are likely to occur during molding without following the deformation of the aluminum plate. On the other hand, if the C content exceeds 50 atomic%, the hardness of the hard coating is insufficient, and the pre-coated aluminum plate cannot have scratch resistance.

(N: 10 atomic% or more and less than 30 atomic%)
N (nitrogen) is a component that imparts flexibility and lubricity to the resin that forms the hard film. When the N content is less than 10 atomic%, the flexibility of the hard coating is insufficient, and cracking or peeling of the coating occurs at the time of molding, and the lubricity is insufficient, so that the slidability with the mold at the time of molding is reduced. Inferior and formability cannot be obtained. On the other hand, when the N content is 30 atomic% or more, the flexibility of the hard coating becomes excessive and the hardness becomes insufficient, and the scratch resistance cannot be obtained.

(Si, O: 10 atomic% or more and less than 30 atomic% each)
Silicon (Si) and oxygen (O) are components that impart hardness to the resin that forms the hard film. When the Si and O content is less than 10 atomic%, the hardness of the hard coating is insufficient and the scratch resistance cannot be obtained. On the other hand, when the content ratio of Si and O is 30 atomic% or more, the hardness of the hard coating becomes excessive, and the moldability is lowered.

(Si / O ratio: 0.8 to 1.2)
The resin forming the hard film has a Si content (atomic%) of 0.8 times or more and 1.2 times or less of the O content (atomic%). When Si exceeds 1.2 times with respect to O, a hard film will become hard too much and a moldability will fall. On the other hand, if the Si content is less than 0.8 times the O content, the hardness of the hard coating is significantly reduced even if the content (10 atomic% or more) is satisfied. In addition, defects such as tearing of the hard coating may occur during molding.

  In addition to C, N, Si, and O, the resin that forms the hard film of the precoated aluminum plate according to the present invention may contain H (hydrogen). The H content is not particularly limited, but is preferably less than 10 atomic%, that is, the total content of C, N, Si, and O is preferably more than 90 atomic%.

  The content of C, N, Si, O in the hard coating formed on the surface of the pre-coated aluminum plate is determined by, for example, glow discharge emission analysis (GD-OES) method or X-ray photoelectron spectroscopy (XPS or ESCA) method. It is obtained by measuring. When measuring from the surface of the hard coating on the pre-coated aluminum plate to the depth of the hard coating thickness, components of the hard coating such as C, and Al, which is a component of the aluminum plate, or additional elements of the aluminum alloy are detected. The Since the elements detected as components of the hard coating are C, N, Si, and O, these atomic ratios (atomic%) may be measured and managed.

(Absorption peak of infrared absorption spectrum: wave number 2100-2300 cm ⁻¹ )
Since resins having C, C triple bonds or C, N triple bonds, such as nitrile rubber, have high toughness, hard coatings containing such resins are particularly high in pre-coated aluminum plates while having sufficient hardness. It is suitable for a member that imparts moldability and performs molding with a high degree of processing such as drawing. Since these bonds have an absorption peak in the range of wave numbers 2100 to 2300 cm ⁻¹ in the infrared absorption spectrum, it is preferable that the pre-coated aluminum plate according to the present invention has an absorption peak in this range. Such a hard film can be obtained by baking a paint prepared so as to be a resin of the predetermined component at a relatively high temperature or for a long time as will be described in the production method described later. That is, it is presumed that C, C triple bonds and C, N triple bonds are generated in the resin when the curing by heating sufficiently proceeds. In particular, by applying paints such as silicone resins and alkali silicate-containing resins that contain an alkynyl group or nitrile group at the end, a resin having a triple bond in the unit structure is formed by a crosslinking reaction by heating, and has high toughness and high thermal conductivity. It is preferable because a stable hard film can be obtained.

  The resin coating for forming a hard film can be continuously coated with a roll coater from the viewpoint of the productivity and cost of pre-coated aluminum sheets, and is cured by baking for a short time of about 20 to 60 seconds in a baking furnace. The material to be made is desirable. Examples of such a resin coating material include methyl silicone resin, phenyl silicone resin, aminoalkyl silicone resin, epoxy-modified silicone resin, urethane-modified silicone resin, acrylate-containing silicone resin, and alkali silicate-containing resin.

  The hard film is a resin containing C, N, Si, and O, but may contain other components as necessary. For example, one or more lubricants such as palm oil, carnauba wax, polyethylene wax, and microcrystalline wax may be included in order to further improve press moldability. In addition, hard coatings are used for commonly used pigments, pigment dispersants, fluidity modifiers, leveling agents, anti-cracking agents, antiseptics, in order to ensure paintability and general performance as a pre-coated metal plate. An agent, a stabilizer, etc. may be contained.

[Production method of pre-coated aluminum plate]
Next, the manufacturing method of a precoat aluminum plate is demonstrated. The method for producing a precoated aluminum plate according to the present invention includes an application step of applying a paint containing C, N, Si, and O on one or both sides of an aluminum plate, and baking the applied paint at 210 ° C. or higher and 280 ° C. or lower. And a baking step for forming a hard film.

(Coating process)
The coating can be applied by any method such as brush coating, roll coater, curtain flow coater, roller curtain coater, electrostatic coating machine, blade coater, die coater, etc. However, a simple roll coater is preferable. In addition, it is applied in consideration of the conveyance speed of the aluminum plate, the rotation direction and rotation speed of the roll coater, etc., so that a hard film having a desired thickness in the range of 0.2 to 10 μm is formed on the surface of the aluminum plate. Adjust the amount appropriately.

  You may perform the degreasing process which degreases the surface of an aluminum plate before performing an application | coating process. For example, the surface of the aluminum plate is sprayed with an alkaline aqueous solution and then washed with water.

  Furthermore, you may perform the base treatment process which forms a base treatment layer in the surface of an aluminum plate before performing an application | coating process. For example, a phosphate chromate treatment is performed on the aluminum plate after the degreasing step to form a phosphate chromate film.

(Baking process)
The aluminum plate coated with the paint is baked to harden the paint to form a hard film. The baking temperature is preferably 210 ° C. or higher and 280 ° C. or lower, and in such a temperature range, a hard film can be obtained by a short baking process of 20 to 60 seconds. The baking temperature is the maximum temperature reached by the aluminum plate. If the baking time is less than 20 seconds, there is a possibility that baking is insufficient. On the other hand, even if baking is performed for more than 60 seconds at this baking temperature, there is no further curing and productivity per hour is reduced. To do. On the other hand, if the baking temperature is less than 210 ° C., the baking treatment for 20 seconds results in insufficient curing of the paint, and the hardness of the hard coating becomes insufficient. More preferably, the baking temperature is 230 ° C. or higher and the baking time is 20 to 50 seconds. According to such a relatively high temperature baking treatment, a resin having a C, C triple bond or a C, N triple bond is easily formed. However, when the baking temperature exceeds 280 ° C., the paint starts to decompose, so that the hardness of the hard coating decreases. Alternatively, even when the baking temperature is less than 210 ° C., a hard film can be obtained by performing a baking process for a long time. Specifically, if the baking treatment time is 1 hour, the baking temperature can be 130 ° C., and further the baking temperature is 150 ° C., thereby having C, C triple bonds and C, N triple bonds. A resin is formed. The baking treatment can be performed using a hot air furnace, an induction heating furnace, a near infrared furnace, a far infrared furnace, an energy beam curing furnace, or the like.

  As mentioned above, although the form for implementing this invention was described, the Example which confirmed the effect of this invention is demonstrated concretely compared with the comparative example which does not satisfy | fill the requirements of this invention below. In addition, this invention is not limited to this Example.

[Production of test materials]
(Pretreatment of aluminum plate)
As the aluminum plate, a JIS 5182H18 material having a thickness of 0.5 mm was applied. The aluminum plate was degreased with an alkaline aqueous solution and then subjected to a phosphoric acid chromate treatment to form a phosphoric acid chromate film of 20 mg / m ^{2 in} terms of Cr on both sides.

(Hard film formation)
Resin paints having different components were prepared, and applied on one side of the aluminum plate after the base treatment with a roll coater while changing the amount. This aluminum plate was subjected to a baking treatment by heating for 30 seconds (test material No. 14 is 1 hour) with the maximum temperature of the aluminum plate as shown in Table 1 in a continuous furnace. A test material was prepared. The test material No. For 25, as a film according to the invention of Patent Document 1, a silica film was formulated as a (SiO ₂₎ 20 parts by weight was formed in 80 parts by weight of the epoxy resin after curing (solids).

[Measurement of hard coating]
With respect to the obtained coating film of the test material, the film thickness, components, and infrared absorption spectrum were measured and shown in Table 1. However, the test material No. No. 27 is shown in Table 1 as “-” (infrared absorption spectrum is “(−)”) without observing the infrared absorption spectrum and evaluation described later, because an appearance defect was observed in the film.

(Hard film thickness, components)
About the test material, the film thickness of the film was measured using an eddy current film thickness meter. In addition, by GD-OES, the surface from the coating surface of the test material to the depth corresponding to the thickness of the coating is measured to detect all the elements contained in the coating, and C, N, Si, O The average value in the depth direction of the atomic ratio was calculated.

(Infrared absorption spectrum of hard coating)
About the film | membrane of the test material, the infrared absorption spectrum was observed with the Fourier-transform infrared spectrophotometer (FT-IR). Table 1 shows “◯” when absorption peaks are observed in the range of wave numbers 2100 to 2300 cm ⁻¹ and “−” when no absorption peak is observed.

[Evaluation]
(Hardness of hard coating)
About the test material, according to JIS K5600-5-4, the pencil hardness of a film | membrane is measured by flaw determination, and it shows in Table 1. A pencil hardness of 4H or higher is accepted.

(Scratch resistance)
Steel wool was pressed against the surface of the test material at 100 gf and slid 30 times at a distance of 10 cm, and then the surface state of the film was visually observed. Those with no noticeable wrinkles were accepted, those with minute wrinkles remaining were marked with “○”, and those with no wrinkles observed were marked with “◎”, respectively. Those shown in Table 1 as “x” as defective.

(Drawing formability)
As the moldability, the drawability was evaluated. Using an Erichsen tester, the test material was fixed by bringing the surface on which the film was formed into contact with the die, and the drawing height was 20 mm with a φ43 mm cylindrical punch so that this surface would be the outside of the molded product. Then, after drawing the film, the surface state of the film was visually observed. If the film has no abnormalities such as peeling or conspicuous wrinkles, it is accepted, the film is not peeled but minute wrinkles are observed with `` ○ '', those where no wrinkles are observed are `` ◎ '', Those shown in Table 1 are shown as “x” in Table 1 as defective.

  As shown in Table 1, the test material No. Nos. 1 to 14 are C, N, Si, O content of the film, Si / O ratio, and film thickness all satisfying the scope of the present invention, so that a hard film having sufficient hardness and formability is obtained. As a result, scratch resistance and drawability were good. In addition, through the preparation and evaluation of the test materials, the paintability and corrosion resistance have no practical problems. In particular, specimen No. 1 having an absorption peak of an infrared absorption spectrum derived from a C, C triple bond or a C, N triple bond by high temperature baking treatment. No. 13 was excellent in both scratch resistance and drawability.

  On the other hand, the test material No. 15 to 24 are comparative examples in which the components of the film are outside the scope of the present invention. Specimen No. In No. 15, since the C in the film was insufficient, the film became excessively hard and the lubricity decreased, and as a result, drawability was not obtained. Specimen No. In No. 16, since the C in the film was excessive, the hardness of the film was insufficient, and the scratch resistance was not obtained.

  Specimen No. Since N in the film of 17 was insufficient, the flexibility and lubricity were insufficient, and the drawability was not obtained. On the other hand, the test material No. Since N in the film was excessive, No. 18 was not flexible due to excessive flexibility.

  Specimen No. In Nos. 19 and 21, since Si and O in the film were insufficient, the hardness of the film was remarkably reduced, and the scratch resistance and drawability were not obtained. Specimen No. In Nos. 20 and 22, since Si and O in the film were excessive, the film became excessively hard and drawability was not obtained.

  Specimen No. In No. 23, since Si in the film was too small relative to O, the hardness of the film was remarkably lowered, and the scratch resistance and drawability were not obtained. Specimen No. In No. 24, since there was too much Si with respect to O in the film, the film became excessively hard and drawability was not obtained.

  Specimen No. No. 25 is a test material on which a film according to the invention of Patent Document 1 is formed, and hardness is obtained by silica added to the resin material. However, in the evaluation of the scratch resistance, abrasion wear occurs, The stickiness was not obtained.

  Specimen No. Nos. 26 and 27 are comparative examples in which the film components are within the range of the present invention but the film thickness is out of the range. Specimen No. In No. 26, the film thickness of the film was insufficient, and scratch resistance was not obtained. On the other hand, the test material No. In No. 27, an excessively thick film was formed, and the film was cracked, resulting in poor appearance.

Claims (3)

A pre-coated aluminum plate in which a hard film having a film thickness of 0.2 μm or more and 10 μm or less is formed on one side or both sides of an aluminum plate,
The hard coating is made of a resin containing C in a range of 30 atomic% to 50 atomic% and N, Si, and O in a range of 10 atomic% to less than 30 atomic%, and the Si is 0.8 times the O. A precoated aluminum plate characterized by having a content (atomic%) of 1.2 times or more. 2. The precoated aluminum plate according to claim 1, wherein the hard coating has an absorption peak of an infrared absorption spectrum in a wave number range of 2100 to 2300 cm ⁻¹ . It is a manufacturing method of the precoat aluminum plate according to claim 1 or 2,
An application step of applying a paint containing C, N, Si, O to one or both sides of an aluminum plate;
A baking method for baking the applied paint at 210 ° C. or higher and 280 ° C. or lower to form a hard film, and a method for producing a precoated aluminum plate.