JP2007320204A - Aluminum paint - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an aluminum coated material excellent in press moldability such as dragging resistance or the like and not causing the damage of a coating film by coating the surface of a resin coating film with a predetermined wax composition. <P>SOLUTION: The aluminum coated material is equipped with the aluminum base material comprising aluminum or an aluminum alloy, the resin coating film formed on at least one side of the aluminum base material and a molten mixed wax composition composed of 10-80 wt.% of the lanolin wax applied to the surface of the resin coating film and 20-90 wt.% of paraffin wax. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an aluminum coating material, and in particular, an aluminum coating material in which a resin coating film is provided on at least one surface of an aluminum base material, and a wax composition having a predetermined composition is applied thereon, and is molded. The present invention relates to an aluminum coating material excellent in lubricity.

  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 working 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. 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.

  As a measure for preventing the galling phenomenon, a method of increasing the amount of wax on the surface of the aluminum coating material can be considered, and it is actually effective to some extent. However, in the press mold with advanced design, the effect of the existing wax is limited, and galling phenomenon often occurs even when a large amount is applied.

  In addition, although a method of applying a processing lubricant to the surface of an aluminum coating material is also conceivable, there are problems such as the need for a cleaning process after processing and the lubricant itself may damage the resin coating film. However, it was not always an effective means.

  As a result of intensive investigations, the present inventors have found a wax composition excellent in press formability, particularly galling resistance, and have solved the above problem by applying it to the surface of an aluminum coating material. .

  That is, the present invention according to claim 1, wherein the aluminum base material made of aluminum or an aluminum alloy, the resin coating film formed on at least one surface of the aluminum base material, and 10 to 10 coated on the surface of the resin coating film An aluminum coating material characterized by comprising a melt-mixed wax composition of 80% by weight lanolin wax and 20 to 90% by weight paraffin wax. According to the second aspect of the present invention, the melting point of the paraffin wax is 70 ° C. or less. Further, in the present invention according to claim 3, an undercoat is provided between the aluminum substrate and the resin coating film.

  In the present invention, by applying a predetermined wax composition to the surface of the resin coating film, an aluminum coating material having excellent press moldability such as galling resistance and no damage to the resin coating film can be obtained.

Hereinafter, embodiments of the present invention will be described in detail.
The aluminum coating material which concerns on this invention is obtained by apply | coating the melt mixing wax composition which has a predetermined composition to the resin coating film surface formed in the aluminum base-material surface.

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 paint in which a base resin is dissolved or dispersed in an organic solvent that is a solvent, water, or the like to the surface of an aluminum base, 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.

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 the appropriate flexibility of lanolin wax and the appropriate 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 the 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 occur sufficiently, and the hardness of the mixed wax composition may increase, making it 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 a wax component can be reliably applied uniformly on the surface of the resin coating film, and it is not necessary to add a wax composition to the resin coating film. Further, the coating amount of the melt-mixed wax composition is not particularly limited, but good moldability can be obtained at 5 to 150 mg / m ² , preferably 10 to 100 mg / m ² .

  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 1-8 and Comparative Examples 1-5
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. Further, an aqueous acrylic-modified epoxy paint containing no inner wax (water was used as a solvent) was applied to both phosphoric acid chromate-treated surfaces so that the resin solid content was 5 g / m ² . 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 3 and 4, since the wax component is one component, melt mixing is not performed. Moreover, in Comparative Example 5, 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 8). In Comparative Examples 1 to 5 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 dynamic friction coefficient is less than 0.10, 0.10 or more and less than 0.20, ◯, 0.20 or more and less than 0.30, ◯, 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 phenomenon which occurs 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.

Comprehensive evaluation In the evaluation of the sliding test and the moldability test, the lowest evaluation was taken 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, Examples 1 to 8 satisfying the conditions of the present invention were excellent in slidability and moldability and passed the comprehensive evaluation, and the galling phenomenon could be effectively prevented. In Examples 1, 4 and 5, although the coefficient of friction was slightly high, the moldability test showed good results, 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 the lanolin wax in the wax composition was too large, and in Comparative Example 3, only the lanolin wax was contained. 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 4 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 5, the mixing ratio of the lanolin wax and the paraffin wax was within a predetermined range.

  As described above, in the present invention, lanolin wax and paraffin wax are mixed on the surface of the resin coating film at a predetermined weight ratio and, for example, obtained by melting and mixing at a temperature not lower than the melting point of both waxes and not higher than 200 ° C. By applying the wax composition, an aluminum coating material for molding process having excellent galling resistance can be obtained.

Claims (3)

  An aluminum substrate made of aluminum or an aluminum alloy, a resin coating film formed on at least one surface of the aluminum substrate, 10 to 80% by weight of lanolin wax applied to the surface of the resin coating film, and 20 to 90 An aluminum coating material comprising: a melt-mixed wax composition with a weight percent paraffin wax.   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.