KR20180131048A - The middle liquid paint composition for coating of Diamond Cutting Wheel - Google Patents

Abstract

The present invention relates to a middle liquid glossy transparent coating composition for improving the corrosiveness of aluminum alloy D/C wheels. The present invention aims to enhance running safety with effects of extending the life of the wheels by reinforcing the problem of corrosion caused by relatively weak corner parts and coating film damage which may occur during driving while maintaining basic properties of the D/C wheels as a conventional coating method. The present invention relates to the middle liquid glossy transparent coating composition for improving the corrosiveness of aluminum alloy D/C wheels, which includes a polyester resin, a melamine resin, and an epoxy resin as basic skeletons, and additives such as a leveling agent, a curing accelerator, a corrosion-preventing pigment and the like.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a clear, high-corrosion, clear coating composition for improving the corrosion resistance of an aluminum alloy-

[0001] The present invention relates to a clear and high-gloss liquid transparent clear coating composition for improving the corrosion resistance of an aluminum alloy cutting wheel.

Generally, the process of manufacturing the outer appearance of the wheel to which the aluminum alloy cutting (D / C process) is applied is as follows.

Pretreatment → Primer Coating (Powder) → Drying → Basecoat Coating (Liquid) → Drying → D / C → Pretreatment → Topcoat Clear Coating (Powder) → Drying

D / C process differs depending on shape and design, but it is generally applied to Spoke horizontal plane to remove the dry film of Primer and Basecoat. It is used to expose the material, and one of D / C Basecoat color coated surface It is an automobile wheel manufacturing process to realize different color feeling on a wheel.

Through the following pre-treatment and Topcoat clear coating (powder) coating / drying process, it is possible to secure a certain level of physical properties and to produce wheels with a beautiful appearance.

However, since the D / C surface and the basecoat surface are both present in the pretreatment process after the D / C process, it is difficult to proceed with the coating process on the basis of the D / C surface and the non-uniformity of properties such as corrosion resistance due to the difference in the film thickness after the topcoat Lt; / RTI >

Particularly, there is a limit to obtain a dry film of a certain level of paint due to the difference in surface tension at the structural boundary between the D / C horizontal surface coated with Topcoat alone and the 3-degree painted vertical surface without D / C. / C Causes the frequency and probability of corrosion to occur at the edge of the surface.

The present invention relates to a composition of a high-corrosion-resistant liquid opaque clear coating composition for improving the corrosiveness vulnerability which occurs in the manufacturing process of an aluminum alloy-processed wheel as described above.

The objective is to reduce the unevenness of corrosion by adding a high corrosion-resistant paint layer to the material passed through the pretreatment process after the D / C, and to secure the stability of the physical property by suppressing diffusion when corrosion occurs.

With the global competition intensifying in the automobile market, it is focusing on the development of automobile design that is more sophisticated based on the performance and that meets the sensitivity of each generation.

The automobile wheels are recognized not only for safety but also for the appearance of the car body as well as for the overall feeling of the automobile, thereby stimulating the purchasing mind of the customer.

The previous automobile wheel is basically made of 3Coating based Powder Primer, Color Basecoat, Liquid Topcoat. It is made up of transparency and the spoke area is enlarged to focus on safety. In recent years, special and high quality In order to realize the feeling, safety is secured while reducing the area of the spokes.

In terms of color, not only simply applying paint but also deposition processing such as PVD (physical vapor deposition), removal of painted paint surface by D / C process, exposure of materials, and so on, The number of attempts to mass-produce is increasing.

Structural complexity means that there are more narrow parts of the wheel and more vertical parts where the face and face meet. This is due to the increase of the area to which the paint is applied, the uniformity of the coating agent due to the vortex at the narrow area and the working radius of the coating robot, and the coating film of the D / C wheel is partially thinned Thus causing issues with functionality.

The present invention aims to maximize the production efficiency of the wheel manufacturing company by securing stability against corrosion and extending the life of the parts in mass production of the D / C wheel that realizes a sophisticated design in accordance with the demands of the wheel market described above.

Under these goals, I have noted the following points.

① In developing the paint which improves the corrosion resistance, it should be a paint which does not affect the color of the basecoat color dry film as well as the color retention of the metal material exposed after the D / C. In order to do this, It should be transparent with high gloss to maintain unique color and pattern.

② Adhesion between basecoated dry film and D / C treated wheel material should be maintained.

③ In the existing 3Coat 3Bake, as one layer is added by 4Coat 4Bake method, it is necessary to keep the thin film coating possible considering the impact resistance due to the back coat, and the dry film should maintain a certain level of flexibility.

④ The coating should be uniformly applied to the surface of the substrate, taking into consideration the roughness of the patterned surface of the D / C surface.

⑤ Drying conditions should be applicable to the existing production facilities considering the line composition of the coating company and economical efficiency, and the mixing design should be based on the drying conditions of existing Basecoat at 140 ~ 150 ℃ for 10 ~ 15 minutes.

The present invention having the above object is directed to a transparent intermediate coating composition for improving the corrosion resistance of an aluminum alloy D / C wheel,

30 to 70% by weight of a polyester resin (molecular weight: 10,000 to 20,000)

5 to 20% by weight of a melamine resin,

Epoxy resin (equivalent: 450 to 500 g / eq) 0 to 5% by weight or less,

As a rust-inhibitive pigment containing at least one of an organic pigment and an organic pigment-containing hybrid pigment, the total amount of the pigment components is 0.5 to 5% by weight,

0.1 to 1.0% by weight of an adhesion promoter,

0.1 to 2.0% by weight of a leveling agent,

0.1 to 1.0% by weight of a curing accelerator,

And 30 to 50% by weight of an organic solvent.

(In addition to adhesion promoters and curing accelerators, additives such as wetting agents may be added according to the needs of those skilled in the art.)

Here, the melamine resin is characterized by comprising formaldehyde, melamine, and methanol.

The epoxy resin is obtained by dissolving a solid epoxy resin (base resin of a non-modified Bisphenol-A type)

The leveling agent is at least one selected from the group consisting of Acrylate type and Fluorocarbon type,

The curing accelerator is characterized in that it is at least one selected from the acid catalyst group.

The polyester resin has a molecular weight of 10,000 to 20,000 and an OH value of 9 to 15.

The configuration of the present invention as described above will be further described.

Corrosion of a car wheel is caused by corrosion when a hard object such as a stone strikes the wheel when the wheel is hit and the material is exposed.

In the present invention, the selection of the main resin is linear, and the resin having a small molecular weight and a small reactor is used to induce the reaction to be minimized during the formation of the coating film, thereby realizing a flexible coating film. .

Generally, in an air spray painted coating using a polyester resin as a main resin, a resin having a high molecular weight (generally 10,000 or less) is often applied due to the appearance problems such as leveling, but in the case of a sugar coating, OH value (reactor) was applied to lower the flexibility of the dry film. The larger the molecular weight and the more linear the resin, the better the flexibility of the dry film, but it is difficult to achieve a good appearance and the painting workability such as cracking can be significantly reduced.

Also, the melamine resin is characterized by being composed of formaldehyde, melamine and N-butanol. In selecting the melamine resin, flexibility of the dried film can be improved by applying the melamine having a high reaction start temperature while considering compatibility with the main resin And maximized the utilization of catalysts for drying.

The epoxy resin is characterized by dissolving solid epoxy resin (base resin of unmodified Bisphenol-A type) and liquefying it.

The additives include leveling stabilizers, flow inhibitors, curing accelerators, rust inhibitors and the like.

The present invention is characterized in that the above liquid coating composition is an aluminum alloy D / C wheel painted with an intermediate coating.

The evaluation of the rustproofing property of the present invention was carried out through the CASS test, and the test method is as follows.

① The CASS solution was prepared with sodium chloride, CuCl ₂ 2H ₂ O and pure water (Conductivity: 25 ± 2 ° C: 20us / cm or less) to produce PH 3.1-3.3 at 25 ° C and 4.5-5.5% concentration.

(2) The temperature of the chamber was maintained at 49 ± 1 ° C and the air pressure at 0.1 ± 0.02 MPa to maintain the specimen at 15 ± 2 ° relative to the vertical plane.

③ A nick of 6cm length was drawn on the test specimen, and 240 hours were left in the chamber, and the length of one side of the rust most severe part was measured.

In the present invention, the existing coating equipment is applied and designed in accordance with the heat treatment (drying) condition of the existing paint. According to the present invention, by improving the corrosion resistance of the D / C surface of the aluminum alloy D / C wheel, the spark face having weak corrosion resistance, and the corner portion, the D / C wheel of a complicated structure meeting the design requirement is more stable Physical properties can be realized.

An implementation process of the present invention will be described.

<Production process of aluminum alloy D / C wheel>

First, the process of applying the intermediate liquid transparent coating material of the present invention will be described.

The application process is to degrease the surface of an automotive aluminum alloy wheel with an alkaline degreasing agent, to form a zirconium-based coating on the surface thereof, to thermally coat the surface with a thermosetting powder coating and then to heat treatment at 180 ± 10 ° C. for 10 minutes 1 process;

A second step of applying a basecoat color paint (acrylic or polyester) on the surface of the aluminum alloy wheel that has undergone the first step and then heat-treating the aluminum alloy wheel at 140 占 10 占 폚 for 10 minutes;

A third step of diamond-cutting the front face portion of the spoke so as to conform to the design of the aluminum alloy wheel having been subjected to the second step, followed by alkali degreasing and coating and drying;

A fourth step of coating the aluminum alloy wheel having undergone the third step with the highly corrosion-resistant liquid opaque transparent of the present invention, followed by heat treatment at 140 占 5 占 폚 for 10 minutes;

And a fifth step of coating the surface of the aluminum alloy wheel subjected to the fourth step with an acrylic powder transparent coating material and then performing heat treatment at 160 占 폚 10 占 폚 for 10 minutes.

Each step will be described in detail as follows.

[First Step]

The surface of the aluminum alloy wheel for automobiles is degreased with an alkaline degreasing agent, the surface is coated with a zirconium-based pretreatment agent, the surface is coated with a thermosetting powder coating, and then heat treated at 180 ± 10 ° C. for 10 minutes.

The above-mentioned thermosetting powder coating (for example, polyester-based) has a first purpose of protecting the aluminum alloy wheel, and has a high coating film thickness of 70 to 120 μm with excellent adhesion to the material. It is also excellent in corrosion resistance and resistance to various chemical agents and has good durability.

[Second Step]

The surface of the aluminum alloy wheel which has undergone the first step is coated with Basecoat color paint and dried.

Generally, the wheel that has undergone the first process maintains the temperature of 60 ~ 80 ℃ when applying the second process basecoat color, which can be adjusted to some extent by the company or artificially due to the difference in structure and equipment of production line.

At this time, if the viscosity of the diluted paint is too high, or if the evaporation rate of the solvent composition of the diluted paint is too high or if the temperature of the coated object is high, the paint may be dusted and painted, , Staining occurs.

[Third Step]

The dry coat layer of the Basecoat color coating and the primer coat are removed by the D / C process only on the spoke front face of the wheel on the coated color coated surface to be implemented through the second process. It is a process for alkali degreasing, washing and re-coating treatment to remove used cutting oil, peeled foreign substances and to protect aluminum alloy material on the front of spoke revealed by D / C.

In general, since the basecoat surface and the D / C material surface are present at the same time, the process proceeds in consideration of the coating film of the basecoat surface, and the process of pure water degassing is performed at the final stage and the water drying process is performed to remove moisture.

[Fourth Step]

And the paint of the present invention is applied to the aluminum alloy wheel which has been subjected to the D / C process through the third process, in the same manner as the second process.

The temperature of the spin drying line is generally lower than that of the second step, and the temperature of the wheel is somewhat lower than the material temperature in the second step. However, since the diluting viscosity and the diluent are appropriately selected, Should be.

In order to achieve a good leveling coating, a setting interval and time for transparent coatings to spread can be set.

[Step 5]

 The wheel having undergone the fourth step is painted with an acrylic powder transparent paint, and then subjected to heat treatment at 160 占 10 占 폚 for 10 minutes.

Acrylic powder transparent paint is a product mainly composed of acrylic resin which is excellent in weather resistance and chemical resistance, and has excellent workability and excellent appearance in smoothness.

In general, the powdery acrylic clear paint is painted over 70 ~ 120 ㎛ and the dry paint on the narrow part of the wheel structure is not too low.

Next, the liquid coating material for the present invention will be described.

<Medium Liquid Coating>

Generally, polyester resin is superior in workability and adhesion to non-ferrous metals than acryl resin, and is widely used for coating and PCM steel sheet coatings.

The larger the molecular weight, the more linear the resin is, the better the workability, and the better the impact and interlayer adhesion, the lower the dilution solid content of spray application and the lowering of the leveling and the increase of the weight.

Application of the spray method to the coating of resin with a molecular weight of 20,000 or more has limitations in workability such as leveling and sealing. Therefore, the appearance comparison work through the experiment is considered and based on the result of CASS test of resin alone, Resin.

Since melamine resin affects the drying properties and processability of the paint, it should be focused on the possible flexibility in order to secure the adhesion from paint film shrinkage due to the chipping test and the coating film on the top coat. do.

The hardness of the melamine resin was determined by controlling the content of the melamine resin, the hardening condition, and the hardening accelerator.

Epoxy resins are excellent in adhesion to metals, corrosion resistance and chemical resistance, but they are limited in their use due to yellowing and chalking problems, and the kind and amount of additives and the amounts of additives such as HALS stabilizers should be considered when applying paints.

In general, rust preventives are effective in the case of inorganic materials, but when applied to paints, they have inherent colors of the pigments themselves, causing gloss retention and hazing.

But the object of the present invention is limited in its kind and amount of use when applied to a clear transparent coating material.

It should be noted that in selecting the solvent, the solubility of the resin and the temperature of the coating at the time of application of the coating are taken into account and the proper evaporation rate is maintained.

Hereinafter, the process for producing the liquid coating material of the present invention will be described.

[First Step]

In a step of weighing each composition, the solution of polyester & melamine & epoxy resin is weighed in a tank while stirring using a balance so as to have the composition ratio as described above.

[Second Step]

Solvent (solvent, ester, ketone, alcohol, etc.) that dissolves the resin and mixes well is weighed into the tank using a balance while stirring.

[Third Step]

The weighed composition is stirred and mixed at 500 to 2000 rpm at high speed for about 30 minutes.

[Fourth Step]

Various additives are appropriately diluted with an ester-based solvent and metered in. (In the present invention, additives and a solvent are diluted 1: 1 and applied.)

[Step 5]

The mixed composition is stirred at 500 to 2000 rpm at high speed for about 30 minutes.

[Step 6]

And filtering the mixed composition by a filtration step to remove dust or foreign matter which may be incorporated into the production process, the manufacture of the liquid paint is completed.

The liquid coating composition thus prepared was diluted with a work-only thinner (diluted with Ford cup # 4, 12 to 15 seconds) and sprayed with a powder primer (for example, polyester-based, film thickness: 70 to 130 탆) Liquid Basecoat (eg acrylic or polyester based, film thickness: 15 ~ 20㎛) is coated on the coated material to be 10 ~ 15㎛ on the basis of dry film thickness. The above coating method is the same as the coating method of the conventional liquid paint, and the coated substrate is heated and cured in the indirect heat drying type drying furnace in a proper amount of heat. The thermosetting acrylic powder coating is transparent (70 to 120 μm) on the cured liquid coating film and is then dried and completed.

Hereinafter, the present invention will be described in more detail by way of examples. However, this is for the purpose of helping understanding of the present invention, and the scope of the present invention is not limited by the examples.

[Experiment 1]

A liquid coating composition was prepared using the compositions shown in Table 1 below, and resin sorting and adhesion / appearance comparison tests were conducted.

1) Polyester resin 1

A polyester resin having Mn of 10,000 to 14,000, OH Value of 9 to 15, and NV of 48 to 52

2) Polyester resin 2

A polyester resin having Mn of 18,000 to 25,000, OH Value of 10 to 12, and NV of 48 to 52

3) Polyester resin 3

A polyester resin having Mn of 14,000 to 18,000, OH Value of 9 to 15, and NV of 48 to 52

4) Acrylic resin

An acrylic resin having Mn of 2,000 to 5,000, OH Value of 3 to 4 and NV of 48 to 52

5) Melamine resin 1

Vis (G #, 25 ° C): J to M, NV: 58 to 62, Butoxy Melamine

6) Melamine resin 2

Vis (G #, 25 ℃): Z ~ Z1, NV: 78 ~ 82, Metoxy Melamine (Formaldehyde, Melamine, Methanol)

7) Epoxy resin

1001 GRADE, NV: 63-67 [Equivalent amount: 450-500 g / eq] obtained by dissolving solid epoxy resin (base resin of unmodified Bisphenol-A type)

8) Leveling agent

The silicone additive was excluded in consideration of the top coat and adhesion, and the leveling additive of the fluorocarbon type was applied in the above example.

9) Solvent

The solvent was composed of a diluting agent in consideration of wettability and volatility rate of the material, and Cyclohexanone, Kocosol # 100 and Kocosol # 150 were used as main agents.

10) Other preparations

The same amount of the adhesion promoter, the curing accelerator, and the wetting agent were added in the same ratio.

(Acrylic / melamine type and polyester / melamine type) were painted / dried, and the above blended transparent was painted and dried at 140 ° C. for 10 minutes, and then the upper powdery body was transparently finished, and each appearance state and adhesion test ASTM-D3359, 2 mm spacing).

The diluent used in the spraying process was mainly hydrocarbon and polyhydric alcohol. The viscosity was measured by Ford Cup # 2 and diluted to 12 ~ 13 seconds.

The experimental results were evaluated as follows.

In the case of Examples 1, 3 and 5, in the case of Example 4 where the main resin and melamine were poorly mixed so that the sample became hazy or gelated and the main resin molecular weight was relatively large, 6 and compared with the relative comparison was visually insignificant.

[Experiment 2] - Experiment of rustproof pigment addition

Examples 2 and 6, Comparative Examples 1 and 2, and Examples 6 and 6 were each subjected to a comparative test according to a wheel physical property standard to which a rust preventive pigment was added.

1) The physical properties test was performed based on the D / C surface of the wheel.

The painting process was wheel D / C, pretreatment (zirconium type), clear coating for test, and acrylic powder transparent. The test clear coatings were dried at 140 ° C for 10 minutes and then dried at 10 to 15 microns. The acrylic powders were dried at 160 ° C for 10 minutes and dried to a dry film thickness of 80 to 100 microns.

2) The test was conducted with acid, alkali, adhesion, salt spray, CASS, and chipping resistance test.

(1) Tests were carried out on the corrosion resistance, appearance and adhesion of each resin according to the resin selected in the above test.

The viscosity of the same diluting solvent as in [Experiment 1] was maintained and the same experimental specimen work was performed.

The film leveling property shows a sensitive difference depending on the molecular weight of the main resin, the type of each resin, the shrinkage force depending on the degree of resin reactivity, and the dissolution power of the diluting solvent.

In [Experiment 1], polyester resin was able to achieve satisfactory leveling even when a resin having a molecular weight of about 10,000 to 18,000 was applied, considering the workability in solvent selection, and using a large amount of the propellant.

(2) Other compositions affecting the reactivity were added in the same ratio as in Experiment 1.

③ Leveling additives were added to acrylate or fluorocarbon system proportionally to the resin solids, except for silicone series, considering the adhesion to the powder transparent top coat.

Silicone leveling additive is excellent in its effect, but it has a high possibility of adhesion failure with the upper layer coating film because it forms a film on the upper layer of the dry film.

④ Appearance (leveling) and adhesion (ASTM-D3359, 2 mm spacing), re-stiffness (ASTM-D3359, 2 mm spacing) and relative corrosion resistance were compared.

⑤ As a result of the above test, it was confirmed that there is a consistent positive effect on the improvement of corrosion resistance according to the presence or absence of the anticorrosive pigment.

It was confirmed that the corrosion length was shortened in Example 2 in which the anticorrosive pigment was not added and in the salt spray test and the CASS test in Example 2-1 in which the anticorrosive pigment was added and in Example 6 And the test results of Example 6-1 in which the anticorrosive pigment was not added, a consistent test result in which the corrosion length is reduced by adding the anticorrosive pigment can be confirmed.

Claims (4)

30 to 70% by weight of a polyester resin,
5 to 20% by weight of a melamine resin,
Epoxy resin (equivalent: 450 to 500 g / eq) 0 to 5% by weight or less,
As a rust-inhibitive pigment containing at least one of an organic pigment and an organic pigment-containing hybrid pigment, the total amount of the pigment components is 0.5 to 5% by weight,
0.1 to 1.0% by weight of an adhesion promoter,
0.1 to 2.0% by weight of a leveling agent,
0.1 to 1.0% by weight of a curing accelerator,
And 30 to 50% by weight of an organic solvent.
A high modulus corrosion resistant liquid transparent clear coating composition for improving the corrosion resistance of an aluminum alloy wheel. The method according to claim 1,
Wherein the melamine resin is composed of Formaldehyde, Melamine, and Methanol. The composition of claim 1, wherein the melamine resin is formaldehyde, melamine, and methanol. 3. The method of claim 2,
The epoxy resin is obtained by dissolving and solidifying a solid epoxy resin (a base resin of a non-modified Bisphenol-A type)
The leveling agent is at least one selected from the group consisting of Acrylate type and Fluorocarbon type,
Wherein the curing accelerator is at least one selected from the acid catalyst group.
A high modulus corrosion resistant liquid transparent clear coating composition for improving the corrosion resistance of an aluminum alloy wheel. 4. The method according to any one of claims 1 to 3,
Wherein the polyester resin has a molecular weight of 10,000 to 20,000 and an OH Value of 9 to 15. [
A high modulus corrosion resistant liquid transparent clear coating composition for improving the corrosion resistance of an aluminum alloy wheel.