JP2007320205A - Aluminum coated material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an aluminum coated material excellent in dragging resistance and build-up resistance by coating the surface of a resin coating film containing a predetermined type of wax with a predetermined molten mixed wax composition. <P>SOLUTION: The aluminum coated material is equipped with an aluminum base material comprising aluminum or an aluminum alloy, the resin coating film formed to at least one side of the aluminum base material and containing 0.2-5 wt.% of polyethylene wax with respect to a resin solid component as the lubricant and a wax composition coated on a molten mixed wax composition consisting of 10-80 wt.% of lanoline wax and 20-90 wt.% of paraffin wax and being applied to the surface of the resin coated film in an amount of 5-below 100 mg/m<SP>2</SP>. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an aluminum coating material, and in particular, an aluminum coating in which a resin coating film containing a predetermined type of wax is provided on at least one surface of an aluminum base and a wax composition having a predetermined composition is applied thereon. The present invention relates to an aluminum coating material in which the galling phenomenon of a resin coating film due to insufficient lubricity in molding processing is reduced, and the build-up of a wax component to a mold is reduced.

  Aluminum or aluminum alloy (hereinafter referred to as “aluminum substrate”) is lightweight, has appropriate mechanical properties, and has excellent characteristics such as aesthetics, moldability, and corrosion resistance. It is widely used for various types.

  In particular, a molding process in which a coiled aluminum base plate is continuously supplied to a press machine is excellent in productivity, and thus is widely used in the above applications. In order to further improve the corrosion resistance and anti-elution properties of the aluminum base material for such applications, the surface of the aluminum base material may be coated with a resin paint in order to prevent scratches, etc. Many. At this time, the aluminum substrate is usually subjected to some surface treatment (for example, phosphate chromate, chromate chromate, zinc phosphate or zirconium phosphate).

  The relationship between the resin coating of aluminum substrate and press processing is similar to the pre-coating method in which the resin coating is applied after pressing, such as aluminum can lids and some heat exchanger fins, and the aluminum can body and automobile panels. It is divided into the post-coating method in which coating is performed after pressing.

  In the pre-coating method, a lubricant layer is generally formed on the surface of the coating film in order to improve the press formability of the coated aluminum base material (hereinafter referred to as “aluminum coating material”). Yes. Specifically, plant wax, animal wax, mineral wax or petroleum wax is added as an inner wax to the coating film coating component, and the wax component is deposited on the coating film surface by painting and baking. And a method of applying petroleum wax or the like as an outer wax on the surface of the coating film after coating. According to these methods, lubricity is imparted to the aluminum coating material, so there is a certain effect in improving the press formability. As a result, it contributes to the stability of product quality, the extension of the press die life, etc. To do.

Various proposals have been made regarding the formation of such a lubricant layer. In Patent Document 1, 0.2% by weight or more of lanolin is added as an inner wax to the resin solid content of the resin coating film, and paraffin wax or microcrystalline wax is used as an outer wax in an amount of 10 to 100 mg / m ^2. The method of apply | coating by the quantity of is described. Patent Document 2 describes that 70% or more of paraffin wax used as outer wax is orthorhombic paraffin.
: JP 2002-28396 A : JP-A-6-254490

However, the above-described prior art has the following problems.
That is, in recent years, the press mold design has become more sophisticated in response to the increasing press speed and the demands for machining accuracy. However, if an aluminum coating material based on the prior art is applied to such a press machine, the lubricity is insufficient. Therefore, in parts that receive a strong force during processing, such as the end face of the aluminum can lid, the score part, the rivet part, etc. A so-called galling phenomenon such as seizure of the resin coating film on the mold or peeling of the resin coating film may occur. Such a galling phenomenon seriously impairs the commercial value of a press-formed product, and measures to prevent it have been demanded.

  Also, as a countermeasure against galling, a method of applying a processing lubricant to the surface of an aluminum coating material can be considered, but a cleaning step is required after processing, and the lubricant itself may damage the resin coating film. It is not always an effective means.

  In addition to the galling phenomenon, a so-called build-up phenomenon may occur in which the wax component adheres to and accumulates on the mold. Since the mold does not function as designed due to the wax component deposited on the mold and causes processing accuracy of the molded product and damage to the molded product, countermeasures are strongly demanded.

  The build-up phenomenon is a characteristic that conflicts with the galling phenomenon, and as a countermeasure for build-up, it is easiest to reduce the total amount of wax components on the surface of the aluminum coating material, and this is effective to some extent. However, in a highly designed press die, reducing the amount of the wax component directly leads to insufficient lubricity and often leads to molding defects such as galling of the resin coating film. Therefore, simply reducing the total amount of wax components is not sufficient to solve the problem.

Furthermore, Patent Document 3 discloses a method of limiting the amount of aluminum powder adhering to the surface of an aluminum coated plate to 0.05 mg / m ² or less. In this method, it is possible to prevent a hard material made of aluminum powder and a lubricant component from being deposited on the metal coating plate contact surface as a deposit. However, maintaining the cleanliness of the production equipment for aluminum coated plates is a factor in increasing costs, and if an edge-cutting process (trimming) or a dividing process (slit) is performed after painting the aluminum painted plate, it is clean. There is also a problem that it is difficult to maintain the degree.
: JP 2003-275679 A

  As a result of intensive studies, the inventors have found that an aluminum coating material excellent in galling resistance and build-up resistance can be obtained by satisfying the conditions described in the claims. It came to solve.

The present invention according to claim 1 is formed on at least one surface of an aluminum substrate made of aluminum or an aluminum alloy and at least one surface of the aluminum substrate, and polyethylene wax as a lubricant is 0.2 to 5 wt. % Of a resin coating film, and a wax composition coated on the surface of the resin coating film in an amount of 5 mg / m ² or more and less than 100 mg / m ² , comprising 10 to 80% by weight of lanolin wax and 20% An aluminum coating material comprising a melt-mixed wax composition with ˜90 wt% paraffin wax.

  In the present invention, the paraffin wax has a melting point of 70 ° C. or lower. According to a third aspect of the present invention, a base film is provided between the aluminum base material and the resin coating film.

  According to the present invention, an aluminum coating material excellent in galling resistance and build-up resistance can be obtained by applying a predetermined wax composition on the surface of a resin coating film containing a predetermined type of wax.

Hereinafter, embodiments of the present invention will be described in detail.
The aluminum coating material according to the present invention is obtained by applying a molten mixed wax composition having a predetermined composition on the surface of a resin coating film containing a predetermined type of wax formed on the surface of an aluminum base.

A. Aluminum Base As the aluminum base used in the present invention, (pure) aluminum or an aluminum alloy is used. As the aluminum alloy, 3000 series and 5000 series are suitably used. In addition to the aluminum material, galvanized steel, aluminum plated steel, zinc-aluminum alloy plated steel, stainless steel, and the like can also be used. These substrates are preferably used in the form of plates.

B. Resin Coating Film In the present invention, a resin coating film is formed on at least one surface of the aluminum substrate. The resin coating film is formed by applying a base resin and polyethylene wax dissolved or dispersed in an organic solvent, water, or the like as a solvent to the surface of the aluminum substrate and baking it after drying. A roll coating method is used for applying the paint, and the baking temperature is usually 200 to 300 ° C.

  In addition, before coating | coated resin to an aluminum base material, the surface treatment is given to the surface, and a base film is formed, The adhesiveness of a resin coating film becomes favorable and contributes to the improvement of a moldability. Examples of the base film include non-chromate films such as zirconium phosphate films and titanium phosphate films, and chromate films such as phosphate chromate films. Furthermore, it is preferable to pre-treat the aluminum base material by alkali degreasing or the like before the base treatment.

  As the base resin of the resin coating film, an epoxy resin, an epoxy / acrylic resin, a polyester resin, a vinyl chloride resin, an epoxy / urea resin, an epoxy / phenol resin, or the like is used.

  In order to develop build-up resistance, it is necessary to contain polyethylene wax in the resin coating film, and preferably disperse it. This is because the abrasion resistance of the resin coating film is improved by the polyethylene wax. When polyethylene wax is dispersed inside the resin coating film and polyethylene wax is used as the inner wax, since the polyethylene wax hardly precipitates on the surface of the resin coating film, the melt-mixed wax composition applied to the resin coating film surface The effect of is not impaired. Thus, by including polyethylene wax in the resin coating film, it is excellent in galling resistance and excellent build-up resistance even if the amount of the wax component applied to the surface of the resin coating film is small. A coating material is obtained.

  The polyethylene wax content in the resin coating film needs to be 0.2 to 5% by weight based on the resin solid content. If it is less than 0.2% by weight, the effect of galling resistance is not manifested. If it exceeds 5%, the influence of precipitation on the surface of the resin coating film cannot be ignored, and the molten mixed wax composition applied to the surface of the resin coating film And build-up resistance decreases. In addition, when a wax other than polyethylene wax is also contained in the resin coating film, other wax precipitates on the surface of the resin coating film, and the repellency resistance effect of the melt-mixed wax composition applied to the resin coating film surface is improved. This is also undesirable from the standpoint of reducing the amount and complicating the design of the coating material for the resin coating film.

C. Wax lanolin wax and paraffin wax are both known substances, and have been used for aluminum coating materials in conventional methods. Specifically, lanolin wax has been utilized mainly as an inner wax and paraffin wax as an outer wax. In addition, a method for producing a coating material in which a resin paint containing lanolin wax as an inner wax is applied and baked and paraffin wax is applied as an outer wax is also widely used. However, in these conventional examples, it is difficult to properly distribute the inner wax in the resin coating film and on the surface thereof, and each wax component exists independently on the resin coating film surface, It did not have a special function for prevention of galling.

  The present inventors previously mixed lanolin wax and paraffin wax in a solid state with a predetermined blending ratio, and heated and melted the wax composition on the surface of the resin coating film, thereby applying It has been found that an aluminum coated plate excellent in preventing the phenomenon can be obtained.

  In the present invention, not only simply mixing lanolin wax and paraffin wax, but also heating both waxes at temperatures above their melting points and below 200 ° C., and stirring and mixing both waxes in a molten state. The use of a wax composition in which both waxes are melt mixed is characterized.

  If the heating temperature does not reach the melting point of lanolin wax and paraffin wax, it is a matter of course that a molten mixture of both waxes cannot be obtained. The melting point of lanolin wax is about 35 to 50 ° C., and the melting point of paraffin wax is about 40 to 75 ° C. On the other hand, if the heating temperature exceeds 200 ° C., the flash point of paraffin wax is about 210 ° C. or higher, which is not preferable because there is a risk of explosion in production and both waxes are susceptible to oxidative alteration. Furthermore, from the viewpoint of energy cost, it is preferable to set the heating temperature to 100 ° C. or less.

  As for the mixing ratio of the lanolin wax and the paraffin wax, it is necessary that the weight ratio of the lanolin wax in the entire mixed wax is 10 to 80% and the weight ratio of the paraffin wax is 20 to 90%. That is, according to the experimental findings of the present inventors, the wax composition melt-mixed by compatibilizing lanolin wax and paraffin wax at the above-mentioned weight ratio is suitable for lanolin wax and moderate paraffin wax. It has excellent properties combined with a high viscosity.

  If the weight ratio of lanolin wax is less than 10%, that is, if the weight ratio of paraffin wax exceeds 90%, the melt-mixing effect of both does not appear, and its lubricity is almost the same as that of paraffin wax alone, and a galling phenomenon Cannot be prevented. Specifically, when the mold and the resin coating film slide by processing, the effect of spreading the wax is not exhibited, so that a sufficient lubricating action cannot be obtained. On the other hand, if the weight ratio of the lanolin wax exceeds 80%, that is, if the weight ratio of the paraffin wax is less than 20%, the melt-mixed wax becomes too soft and the film strength becomes insufficient when sliding. This also reduces the lubrication action.

  As lanolin wax, liquid lanolin (cloud point: about 15 ° C.), purified lanolin (melting point: about 40 ° C.) and hard lanolin (melting point: 43-50 ° C.) are commercially available, and any lanolin wax can be used. In the present invention, purified lanolin having a melting point of about 40 ° C. is preferably used. On the other hand, the paraffin wax is not particularly limited as long as it is commercially available as paraffin wax, but by using a paraffin wax having a melting point of 70 ° C. or less, the galling phenomenon is remarkably prevented. This is presumably because the melting point of paraffin wax has a correlation with its molecular weight, and in the paraffin wax having a molecular weight of melting point of 70 ° C. or less, the compatibility with lanolin wax molecules occurs remarkably. In the case of paraffin wax having a melting point higher than 70 ° C., the compatibility with lanolin wax molecules does not sufficiently occur, and the hardness of the mixed wax composition may increase and it may be difficult to apply.

  The melt mixed wax composition is prepared as follows. Using a stirrer at room temperature, the solid lanolin wax and paraffin wax are mixed at the above blending ratio. Next, the solid mixed wax is mixed with stirring at the heating temperature using a stirring member such as a stirring bar. The mixing is appropriately selected depending on the heating temperature, the stirring means, the stirring speed, and the like, but usually 1 minute or more, and may always be stirred during the heating.

The melt-mixed wax composition thus prepared is applied to the surface of the resin coating film by a normal outer wax method. As the coating method, an electrostatic coating method, a roll coating method or the like is used. The outer wax method is advantageous in that the wax component can be reliably applied uniformly to the surface of the resin coating film. The coating amount of the molten mixture the wax composition, 5 mg / ^{m 2} or more is less than 100 mg / ^{m 2,} preferably good moldability at 5 to 50 mg / ^{m 2} is obtained.

  Although it became possible to prevent the repellency phenomenon as described above, further studies were made to prevent the build-up phenomenon.

  In addition, you may add components other than wax components, such as antiseptic | preservative, a rust preventive agent, a leveling agent, a coloring agent, and surfactant, to a wax composition as needed.

  The preferred embodiments of the present invention will be specifically described below based on examples and comparative examples, but the present invention is not limited to these examples.

Examples 1-10 and Comparative Examples 1-8
A plate-like JIS 5182-H19 alloy (plate thickness 0.26 mm) was used as the aluminum substrate. Both surfaces of this aluminum alloy plate were subjected to alkali etching with an etching amount of 100 mg / m ² using an alkali degreasing agent as a pretreatment. Next, a phosphoric acid chromate treatment (formation amount 20 mg / m ^{2 in} terms of Cr) was performed on both etched surfaces using a phosphoric acid chromate agent. Furthermore, an aqueous acrylic-modified epoxy paint (using water as a solvent) containing polyethylene wax at a ratio shown in Table 2 with respect to the acrylic-modified epoxy resin solid content so that the resin solid content is 5 g / m ^2. It applied to both the phosphoric acid chromate treatment surfaces. Next, the aluminum alloy plate to which the resin paint was applied was baked at an ambient temperature of 270 ° C. for 30 seconds (the plate arrival temperature was 250 ° C.) to form a resin coating film.

A melt-mixed wax composition was prepared using the lanolin wax and paraffin wax having the properties shown in Table 1 under the conditions shown in Table 2. This melt-mixed wax composition was applied to the surface of the resin coating film by the electrostatic coating method in the application amounts shown in Table 2. In Comparative Examples 6 and 7, since the wax component is one component, melt mixing is not performed. In Comparative Example 8, since both wax components were mixed at 20 ° C. below both melting temperatures, melt mixing was not performed.
As shown in Table 1, two types of paraffin wax having different melting points were used for one type of lanolin wax.

  The aluminum coating material sample thus produced was subjected to a slidability test, a formability test, and a comprehensive evaluation as follows. The results are shown in Table 3.

Sliding test The dynamic friction coefficient at the 100th reciprocation was measured with a Bowden testing machine (test load 500 g, sliding speed 0.6 mm / second, steel ball diameter 3/16 inch) (Examples 1 to 10 and Comparative Example). 4, 5). In Comparative Examples 1 to 3 and 6 to 8 in which the galling phenomenon occurred before reaching 100 reciprocations, Table 3 shows the number of reciprocations instead of the dynamic friction coefficient. In the evaluation of Table 3, the coefficient of dynamic friction is less than 0.10, 0.10 or more and less than 0.20 is ◯, 0.20 or more and less than 0.30 is △, and ◎, ◯, ◯ △ All passed. Moreover, the case where the galling phenomenon occurred before reaching 100 reciprocations was judged as x.

Moldability test The moldability of the can lid was tested. In a general aluminum can lid press-molding step, that is, after shell processing with a shell press, a step of forming into a can lid shape with a conversion press, 20,000 samples were continuously processed. From this, 50 samples were randomly extracted, and the occurrence of galling phenomenon at the end face, the score part and the rivet part was observed. In the evaluation of Table 3, the case where no galling phenomenon occurs in any of the end face, the score part and the rivet part is ◎, and the case where the number of galling phenomena generated in the end face, the score part and the rivet part is 10 or less. The case where the number of galling phenomenon occurring in any of Δ, the end face, the score part, and the rivet part exceeds 10 is indicated as x. ◎ and △ were accepted and x was rejected.

  Further, with respect to the last 50 sheets that were continuously formed, the number of occurrences of shape defects with respect to the remaining score and the panel shape due to wax build-up on the mold was measured. In the evaluation of Table 3, the case where no shape defect occurred in any of the score remaining thickness and the panel shape was marked as ◎, and the case where a shape defect occurred in at least one of the cases was marked as x. ◎ was accepted and x was rejected.

Comprehensive evaluation In the evaluation of the galling resistance in the sliding test, the moldability test, and the build-up resistance in the moldability test, the lowest evaluation was set as the comprehensive evaluation. At least one of them was x, and the overall evaluation was x and rejected. Other than that, it passed.

  As is clear from Table 3, in Examples 1 to 10 that satisfy the conditions of the present invention, both slidability and galling resistance and buildup resistance in formability are excellent, and the overall evaluation is acceptable, and is good. As a result, it was possible to effectively prevent galling and build-up. In Examples 1, 3, 6, and 7, although the dynamic friction coefficient was slightly high, the moldability test showed a good result, and the overall evaluation was acceptable, and it was confirmed that there was no problem in practical use.

In Comparative Example 1, the amount of lanolin wax in the wax composition was too large, and in Comparative Example 6, only the lanolin wax was contained, so that both galling phenomena occurred. This is considered to be a malfunction caused by the wax composition being too soft.
In Comparative Example 2, the amount of paraffin wax in the wax composition was too large, and in Comparative Example 7, only the paraffin wax was contained. This is presumably because the wax composition did not spread sufficiently on the surface of the resin coating film and the lubricity was insufficient.
In Comparative Example 3, a galling phenomenon occurred because polyethylene wax was not contained in the resin coating film.
In Comparative Example 4, since the content of polyethylene wax in the resin coating film was too much, a build-up phenomenon occurred. In Comparative Example 5, a build-up phenomenon occurred because the amount of the melt-mixed wax composition applied was too large. In Comparative Examples 4 and 5, no galling phenomenon occurred in the sliding test and the moldability test.
In Comparative Example 8, the content of the polyethylene wax and the mixing ratio of the lanolin wax and the paraffin wax are both within a predetermined range, but the melt mixing temperature is 20 ° C., which is lower than the melting point of the lanolin wax and the paraffin wax, and the melt mixing is performed. As it was not done, a galling phenomenon occurred.

  As described above, in the present invention, lanolin wax and paraffin wax are mixed at a predetermined weight ratio on the surface of a resin coating film containing polyethylene wax and melted at a temperature of, for example, 200 ° C. By applying the wax composition obtained by mixing, an aluminum coating material for molding process excellent in galling resistance and build-up resistance can be obtained.

Claims (3)

An aluminum substrate made of aluminum or an aluminum alloy, and a resin coating film formed on at least one surface of the aluminum substrate and containing polyethylene wax as a lubricant in an amount of 0.2 to 5% by weight based on the solid content of the resin; A wax composition applied to the surface of the resin coating film in an amount of 5 mg / m ² or more and less than 100 mg / m ² , comprising 10 to 80% by weight of lanolin wax and 20 to 90% by weight of paraffin wax. An aluminum coating material comprising: a molten mixed wax composition.   The aluminum coating material according to claim 1, wherein the paraffin wax has a melting point of 70 ° C. or less. The aluminum coating material of Claim 1 or 2 which provided the base film between the said aluminum base material and the resin coating film.