JPH07228828A - Resin-coated aluminum material or aluminum alloy material excellent in press moldability, corrosion resistance and coatability - Google Patents

Abstract

PURPOSE:To obtain the subject alloy material excellent in lubricity and corrosion resistance, press moldable with severe processing, coated with a composite resin film with polyethylene wax particles dispersed in a resin. CONSTITUTION:This aluminum allay material excellent in press moldability, corrosion resistance (before and after coated) and coatability bears on its surface 0.2-3gem<2> of a resin film consisting mainly of a resin prepared by blending 0.5-20wt.% of an ordinary temperature-crosslinkable epoxy resin in a water-based urethane resin having active hydrogen therein and also containing 0.5-20wt.% of spherical polyethylene wax particles and 1-30wt.%, on a SiO2 basis, of colloidal silica.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resin-coated aluminium material or aluminum alloy material having excellent press formability, corrosion resistance and paintability, which are used in automobiles, household electric appliances, building materials and the like.

[0002]

2. Description of the Related Art Aluminum materials and aluminum alloy materials (hereinafter simply referred to as aluminum materials) are lightweight and
Moreover, since it has excellent corrosion resistance and designability and has a high specific strength, it is widely used in the fields of household electric appliances and building materials. Further, in recent years, in the field of automobiles as well, from the viewpoints of pollution prevention and energy saving, aluminum materials have been increasingly used for panel materials such as fenders and hoods for the purpose of weight reduction and eventually improvement of fuel consumption. ing.

In such a field, forming processing such as press forming is often performed, but the plastic deformation behavior of an aluminum material is considerably different from that of a cold rolled steel sheet or a surface treated steel sheet due to its metallurgical characteristics. It's different. . Therefore, when the aluminum material is pressed, press oil is usually applied to improve the workability. But,
When such a press oil is applied, the press oil is scattered during the press working to deteriorate the working environment or cause pollution problems, and further, a degreasing step is required after the press working, which is extremely difficult to perform. Inferior in sex.

Further, when press working is performed under severe working conditions, a general low-viscosity working oil may increase the deformation resistance and cause cracking due to insufficient strength. However, it is known that the occurrence of such cracks can be avoided by using a solid lubricant having a high viscosity.

On the other hand, the aluminum material may be used as it is after being pressed, or may be used by being coated to improve its design and corrosion resistance. In the case of the former, when it is incorporated into a product with oil adhered to it, the problem of soiling with oil becomes a problem. It is necessary to form it on the surface of the material, but the lubricant on the surface must be completely removed in order to form a chromate film having excellent coating adhesion. However, when the solid lubricant as described above is used, it is very difficult to completely remove the lubricant adhering to the surface of the breath molded product, and it cannot be removed by the usual cleaning method. ,
Careful cleaning using a degreasing agent with a higher degree of cleaning is required.

[0006]

The present invention has been made to solve the above problems, and is a resin comprising a crosslinked urethane resin in which polyethylene wax particles and colloidal silica are dispersed on the surface of an aluminum material. It is an object of the present invention to provide a resin-coated aluminum material which is excellent in lubricity and is excellent in press-forming property for strong working by forming a film, and is also excellent in corrosion resistance after painting.

[0007]

[Means for Solving the Problems] Press molding according to the present invention
Excellent in corrosion resistance, corrosion resistance (bare and after coating) and paintability
Resin-coated aluminum materials that have active hydrogen in the molecule
Room temperature cross-linking type epoxy resin 1.0
Approximately 20% by weight of resin, spherical poly
Ethylene wax particles 0.5-20% by weight and colloidal
Silica is SiO ₂ As a resin coating containing 1 to 30% by weight
Adhesion amount of membrane is 0.2 to 3g / m² At the surface of aluminum material
It is characterized in that it is formed in.

In the resin-coated aluminum material according to the present invention, urethane resin having active hydrogen, such as carboxyl group or hydroxyl group, in the molecule is used as a main component among the resin components forming the resin coating. The urethane-based resin is prepared as an aqueous resin such as an aqueous dispersion or an aqueous solution. Usually, an aqueous urethane-based resin containing water or a water containing a small amount of a water-soluble organic solvent such as alcohol is preferably used.

The urethane resin having active hydrogen in its molecule is not particularly limited, but can be obtained by the following method. For example, a urethane prepolymer having a terminal isocyanate group is reacted with a compound having a sulfonic acid group or a carboxyl group together with an amino group or a hydroxyl group, for example, an aqueous solution of an alkali salt or an ammonium salt of diaminocarboxylic acid to simultaneously emulsify and emulsify the chain. Or a polyhydroxyl compound, a compound having a quaternary ammonium group and a hydroxyl group in the molecule, or a compound having an epoxy group and a hydroxyl group in the molecule is reacted with polyisocyanate and mixed with water. And the like.

Further, polyether, which is a polymerization product of tetrahydrofuran, propylene oxide, ethylene oxide, etc.,
Dehydration condensation reaction of polyhydric alcohols such as ethylene glycol, propylene glycol, butanediol, hexanediol and polyvalent carboxylic acids such as maleic acid, succinic acid, adipic acid and phthalic acid, or ring-opening polymerization reaction of cyclic ester Polyester obtained by, polyacetal, polyesteramide, polyhydroxyl compounds represented by polythioether, naphthalene diisocyanate,
Diphenylmethane diisocyanate, phenylene diisocyanate, aromatic polyisocyanates such as toluene diisocyanate, or hexamethylene diisocyanate, dicyclohexylmethane diisocyanate, polyisocyanates represented by aliphatic diisocyanates such as xylylene diisocyanate, and the above polyhydric alcohols and ethylenediamine, propylene A urethane is obtained by reacting a chain extender represented by low molecular weight diamines such as diamine, diethylenetriamine, hexamethylenediamine and xylylenediamine with an inert organic solvent such as tetrahydrofuran, acetone, methyl ethyl ketone, ethyl acetate and toluene. There may be mentioned a method in which water containing an appropriate amount of an emulsifier is added thereto, and then the above-mentioned inert organic solvent is distilled off.

Furthermore, a urethane prepolymer having a terminal isocyanate group is reacted with a polyalkylene polyamine such as diethylene triamine to obtain a polyurethane urea polyamine, to which an aqueous solution of an acid is added, or the above polyurethane urea polyamine is subjected to epichloropolyamine. A method of adding hydrin and then adding an aqueous solution of an acid thereto can be mentioned.

In addition to the above, a compound having a terminal amino group obtained by reacting a polyhydroxy compound and a urethane prepolymer having a polyisocyanate group with a diamine is emulsified in water using an emulsifier, and then polyisocyanate is added. In addition, a method of polymerizing can be mentioned.

In the present invention, as the urethane resin having active hydrogen in the molecule, especially JIS K-72 is used.
Shore hardness of the coating measured according to 15 is 30 to 7
Those having a pencil hardness of H or higher are preferably used.

As described above, the resin coating in the present invention contains the urethane resin having active hydrogen in the molecule,
As the crosslinking agent, a room temperature epoxy resin is contained.
According to the present invention, as described above, by using the urethane resin as the resin component for forming the resin film and the room temperature cross-linking type epoxy resin as the cross-linking agent, the desired film strength can be obtained. To obtain a resin-coated aluminum material that has excellent corrosion resistance and paintability, and that suppresses scratches and black discoloration due to temperature rise of the mold and extreme pressure of the sliding surface in press molding of strong processing. You can

That is, according to the present invention, when the urethane resin has a group having active hydrogen in the molecule, for example, a carboxyl group, the epoxy group of the epoxy resin reacts with the carboxyl group. The ester group is formed, and by such cross-linking, the resin film produced is made dense and tough, thereby improving press moldability and corrosion resistance.

Examples of the cross-linking agent for urethane type resins having active hydrogen in the molecule include, in addition to epoxy type resins, for example,
Melamine-based resins, isocyanate-based resins, aziridine-based resins and the like are known, but when these are used as a crosslinking agent, sufficient adhesion of the coating film cannot be obtained, which is not preferable. According to the present invention, excellent adhesion of a coating film can be secured when an epoxy resin is used as a crosslinking agent for a urethane resin having active hydrogen in the molecule.

In the present invention, the room temperature cross-linking type epoxy cross-linking agent has a high reactivity with active hydrogen such as a carboxyl group and a good compatibility with the urethane type resin,
Moreover, a cross-linking reaction occurs at a temperature lower than the softening point of the spherical polyethylene wax particles, and those having good liquid stability are preferably used. As such an epoxy resin,
For example, Denacol EX-313, EX-314, EX
-321, EX-421, EX-512, EX-521
(These are products manufactured by Nagase Kasei Co., Ltd.) and the like.

Such a room temperature cross-linking type epoxy resin is
In the resin coating, it is preferably contained in the range of 1.0 to 20% by weight. The content of room temperature crosslinkable epoxy resin is
When the amount is less than 1.0% by weight, the resin coating does not sufficiently undergo the crosslinking reaction of the urethane resin, the hardness of the obtained coating cannot be improved, and as a result, good press moldability cannot be secured. However, when the content is more than 20% by weight, the resulting resin film deteriorates in lubricity and corrosion resistance. This is because the unreacted epoxy resin remains in the resin coating film, and a large amount of polar groups appear in the coating film, resulting in deterioration of the corrosion resistance of the coating film itself. Particularly, in the present invention, the room temperature cross-linking type epoxy resin is preferably contained in the resin coating in the range of 1 to 10% by weight.

Furthermore, the resin-coated aluminum material according to the present invention contains spherical polyethylene wax particles in the resin coating.
5 to 20% by weight, and colloidal silica as SiO _{2 in} a range of 1 to 30% by weight, and such a resin film is deposited in an amount of 0.2 to 5 g /
It is formed on the surface of the aluminum material within the range of m ² .

In the resin-coated aluminum material according to the present invention, the polyethylene wax particles improve the lubricity and press moldability of the resin coating. When the content of the spherical polyethylene wax particles in the resin coating is less than 0.5% by weight, improvement of lubricity and press formability of the obtained resin coating is still insufficient, while when it exceeds 20% by weight. No particular problem is observed in terms of lubrication performance, but the adhesion between the resin coating and the aluminum alloy material obtained deteriorates, the coating peels off during press working, and the corrosion resistance after working becomes poor. Further, the coating property is also deteriorated, and the adhesion between the coating and the coating is deteriorated.

Further, in the present invention, the softening point of the polyethylene wax particles is preferably in the range of 100 to 140 ° C. When the softening point of the polyethylene wax particles is lower than 100 ° C., the polyethylene wax particles are softened and liquefied due to the increase of the mold temperature during the press working, and the polyethylene wax particles are liquified between the aluminum material and the mold. It becomes cut and the workability deteriorates. On the other hand, when the softening point of polyethylene wax exceeds 140 ° C., the resin coating obtained does not have good lubricity.

Further, when degreasing is carried out as a pretreatment for coating the product after press working, the polyethylene wax particles are peeled off from the resin coating surface by the degreasing, and the diameter of the resin surface is reduced. Many pin poles of 0.1 to 3 μm are generated. This pin pole exerts an anchoring effect that remarkably improves the adhesion between the resin coating and the paint during painting. In particular, this pin pole is produced in a large amount due to degreasing using a solvent, and is more effective. Preferred examples of the solvent used for degreasing include trichlene, triethane, and acetone. Even in the case of degreasing with an alkaline aqueous solution, the same effect can be obtained by adjusting the temperature and pH of the degreasing liquid.

The effect of the pin pole described above is more useful when performing electrodeposition coating after press working. That is,
This is because the hydrogen gas generated at the interface between the aluminum material and the coating material during electrodeposition coating efficiently escapes from this pin pole, thereby significantly improving the coating appearance. In the present invention, in order to maximize the effect of pinholes due to the detachment of such polyethylene wax particles, the polyethylene wax should have a spherical shape, and the particle diameter thereof should be in the range of 0.1 to 3 μm. Preferably there is. When the particle size exceeds 3 μm, it cannot be uniformly dispersed in the aqueous urethane resin in the preparation of the coating agent described later, and as a result, the adhesion of the resulting resin coating to the aluminum material and the coating with the coating material Adhesion deteriorates. Further, when the particle size of the polyethylene wax particles is smaller than 0.1 μm, the effect of improving the lubricity of the resin coating by the polyethylene wax cannot be obtained.

In the present invention, examples of the polyethylene wax include Daijet E-17 (manufactured by Mutual Chemical Co., Ltd.), Chemipearl W-100, W-200, W.
-300, W-400, W-500, WF-640, W
-700 (Mitsui Petrochemical Industry Co., Ltd.), Elepon E-
Commercially available products such as 20 (manufactured by Nichika Kagaku Co., Ltd.) can be preferably used.

In the present invention, the colloid in the resin coating film
Dull silica improves the corrosion resistance and paintability of resin coatings.
It The content of colloidal silica in the resin coating is S
iO ₂ Is in the range of 1 to 30% by weight. For resin coating
The content of colloidal silica is less than 1% by weight
In this case, the obtained coating may not have sufficient corrosion resistance and paintability.
On the other hand, if it exceeds 30% by weight, the silica will increase
To act as an agent, increase the friction coefficient of the coating,
By reducing lubricity, corrosion resistance and coating after processing
Not only does it deteriorate the wearability,
Increases die wear and shortens mold life. In particular, the present invention
In order to maximize the effect of colloidal silica
In order to achieve this, the content in the resin coating is 5 to 25% by weight.
It is preferably within the range.

In the present invention, examples of the colloidal silica include Snowtex SS and Snowtex X.
Commercially available products such as S, Snowtex 40, Snowtex O, Snowtex N, and Snowtex C (manufactured by Nissan Kagaku Co., Ltd.) can be preferably used.

In the present invention, the amount of such resin coating adhered to the aluminum material must be in the range of 0.2 to 3 g / m ² . Adhesion amount of resin film is 0.2g / m
If it is less than ² , the required lubrication effect and the corrosion resistance and paintability after processing cannot be obtained in strong processing. However, if the amount of resin coating adhered exceeds 3 g / m ² , the amount of resin film peeling increases during press working of an aluminum material, and for example, in press molding, the peeled resin accumulates in the mold, It interferes with press molding.

The resin-coated aluminum material according to the present invention is
As described above, so that the content in the resin coating is within the predetermined range, the room temperature crosslinkable epoxy resin, spherical polyethylene wax and colloidal silica are blended with the aqueous urethane resin to prepare a coating agent, This is preferably applied to an aluminum alloy material that has been subjected to a base treatment such as chromate treatment on the material and dried,
It can be obtained by forming a resin film.

In the present invention, the material of the aluminum material is not particularly limited, but for example,
An aluminum material that has been subjected to a chemical conversion treatment such as a chromate treatment or a treatment with a coupling agent such as a silane coupling agent is preferably used as a base treatment for enhancing the adhesion between the resin film and the aluminum material. Among the above, the chromate treatment is a treatment method which is already well known, but in the present invention, the surface of the aluminum material which is the base material is inactive as compared with the galvanized steel sheet, so that In the chemical conversion treatment, as is well known, a treatment liquid prepared by adding a surface etching agent such as sodium fluoride or potassium fluoride to a chromate treatment liquid is preferably used. As the chromate treatment method, any method can be used, for example,
A reaction type or coating type method is preferably used.

[0030]

As described above, according to the present invention, a urethane resin containing a room temperature cross-linking type epoxy resin as a main component, a coating agent containing polyethylene wax particles and colloidal silica is applied to an aluminum material and dried. By doing so, it becomes possible to perform press forming of strong processing without applying press oil, and it is possible to form a resin film having excellent corrosion resistance and paintability (bare and paintability after painting) after processing. . Such a resin-coated aluminum material having high lubricity, high corrosion resistance, and high paintability can be directly coated after press working, and can be electrodeposited by degreasing.

[0031]

The present invention will be described below with reference to examples.
The present invention is not limited to these examples.

Example 1 An aluminum alloy (A5182-0) plate which had been subjected to a chromate treatment (amount of chromium deposited: 10 mg / m ² ) was used as a raw material. Aqueous urethane resin with a Shore D hardness of 51 for the resin coating (Daiichi Kogyo Seiyaku Co., Ltd. Superflex)
0.5-25% by weight of room temperature cross-linkable epoxy resin is added to polyethylene wax particles (particle size 1-2 μm).
m, softening point 110 ° C.) 10% by weight and colloidal silica as SiO ₂ and 10% by weight were added and dispersed in a resin to prepare a coating agent.

This coating agent is applied to the surface of the above aluminum alloy material by a squeezing roll so that the dry adhesion amount is 1 g / m ^2, and dried at 80 ° C. to form a resin coating, and the resin coated aluminum alloy material. Got The resin-coated aluminum alloy material thus obtained was subjected to a sliding test, a press test, a salt spray test and a coating test to examine the dynamic friction coefficient, mold galling resistance, corrosion resistance and coating adhesion.

For comparison, the same urethane resin as above was blended with 5% by weight of a melamine, isocyanate or aziridine crosslinking agent to prepare a coating agent, and a resin coated aluminum alloy material was prepared in the same manner as above. Then, they were also evaluated in the same manner as above.

The coefficient of kinetic friction was determined from the load by sliding at a pressure of 150 kg using a sliding tester. The mold galling resistance and blackening resistance were visually examined for mold galling and black discoloration on the sliding surface of the molded product after press molding using a single-shot press tester. Also, the corrosion resistance is JIS Z-2371.
A salt spray test was conducted according to the method described in 1. Regarding the coating film adhesion, after coating with acrylic and melamine alkyd coatings, the coating film adhesion was examined by a cross-cut and Erichsen test. The results are shown in Table 1.

[0036]

[Table 1]

Example 2 5 wt% of a room temperature crosslinkable epoxy resin was mixed with an aqueous urethane resin having a Shore D hardness of 67 (Neotan manufactured by Toagosei Kagaku Co., Ltd.) to form a spherical resin particle having a particle diameter of 0.1 to 3 μm. Polyethylene wax particles (softening point 100 ° C) 10% by weight
And 10% by weight of colloidal silica as SiO ₂ were added and dispersed to prepare a coating agent.

For comparison, 10% by weight of polyethylene wax particles having a particle size of less than 0.1 μm and polyethylene wax particles having a particle size of 4 μm (softening point 110 ° C.) were added to prepare a coating agent in the same manner. These coating agents were applied on the surface of the same aluminum alloy material as described above so that the dry adhesion amount was 1 g / m ^2, and dried to obtain a resin-coated aluminum alloy material. The results are shown in Table 2.

[0039]

[Table 2]

Example 3 As in Example 1, 5% by weight of a room temperature crosslinkable epoxy resin was added to an aqueous urethane resin having a Shore D hardness of 51 (Superflex manufactured by Daiichi Kogyo Seiyaku Co., Ltd.),
Furthermore, polyethylene wax particles (particle size 1-2 μm,
A coating agent was prepared by dispersing 0 to 25% by weight of particles having a softening point of 100 ° C. and 0 to 35% by weight of colloidal silica particles as SiO ₂ . The coating agent thus prepared was applied to the surface of the same aluminum alloy material as described above to obtain a resin-coated aluminum alloy material having a dry adhesion amount of 1 g / m ² . The results are shown in Tables 3 and 4.

[0041]

[Table 3]

[0042]

[Table 4]

Example 4 In the same manner as in Example 1, the Shore D hardness of the resin coating was 51.
5% by weight of a room temperature crosslinkable epoxy resin was added to the water-based urethane resin (Superflex manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.), and polyethylene wax particles (particle diameter 1-2 μ
m, softening point 100 ° C.) 10% by weight of particles and 10% by weight of colloidal silica particles as SiO ₂ were dispersed to prepare a coating agent.

The coating agent thus prepared was applied to the surface of the same aluminum alloy material as described above in a dry adhesion amount of 1 g.
/ M ² and coated at 80 ° C. to obtain a resin-coated aluminum alloy material. The resin-coated aluminum alloy material was subjected to vapor degreasing with trichloroethane and degreasing with a spray method using a weak alkaline aqueous solution, followed by electrodeposition coating. The results are shown in Table 5.

[0045]

[Table 5]

As the electrodeposition coating, a cationic electrodeposition coating (U-600) manufactured by Nippon Paint Co., Ltd. was used. The coating conditions and the evaluation of physical properties after coating are shown below. Coating conditions Bath temperature 30 ° C Cathode / anode ratio 1/30 Energization time 2.5 minutes Coating film thickness 25 μm Baking conditions 170 ° C × 20 minutes Physical property evaluation method Cross-cut test: After coating, cross-cut with a cutter knife at 2 mm intervals Then, the tape peeling test was performed to examine the peeling of the coating film.

Erichsen test: After coating, an Erichsen tester was used to perform 6 mm extrusion, and a tape peeling test was performed to examine the adhesion of the coating film. Salt spray test: The aluminum alloy material after coating was cross-cut with a cutter knife, and the swollen width of the coating film after 240 hours of salt spray was examined.

Claims (4)

[Claims] 1. Spherical polyethylene wax particles 0.5 to 20% by weight, which is mainly composed of an aqueous urethane resin having active hydrogen in the molecule and 1.0 to 20% by weight of a room temperature crosslinkable epoxy resin. And colloidal silica as SiO ₂
The amount of resin coating containing 1 to 30% by weight is 0.2
A resin-coated aluminum material or aluminum alloy material having excellent press formability, paintability and corrosion resistance, which is formed on the surface of an aluminum material or an aluminum alloy material at 3 g / m ² . 2. The particle size of spherical polyethylene wax particles is
The resin-coated aluminum material or aluminum alloy material according to claim 1, which has a thickness of 0.1 to 3 μm. 3. The melting point of spherical polyethylene wax particles is 1.
It is in the range of 00 to 140 ° C.
The resin-coated aluminum material or aluminum alloy material described. 4. A resin coating is formed on an aluminum material or an aluminum alloy material obtained by subjecting the surface of an aluminum material or an aluminum alloy material to an undercoating treatment for increasing the adhesion to the resin coating of the aluminum material or the aluminum alloy material. The resin-coated aluminum material or aluminum alloy material according to any one of claims 1 to 3.