JPH0347997A - Surface-treated material having superior coatability and corrosion resistance after coating - Google Patents

Abstract

PURPOSE:To remarkably improve corrosion resistance after coating by applying a silane coupling agent to the surface of a base material with a formed composite plating layer contg. a specified amt. of a polymer. CONSTITUTION:A composite plating layer contg. an org. polymer by >=0.01wt.% (expressed in terms of C) is formed on the surface of a base material and a silane coupling agent is applied to the surface of the plating layer. The org. polymer is stuck to the surface of the base material so that the polymer accounts for >=0.1% of the surface area of the base material. The adhesion of coating material to the surface-treated material is improved.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a surface treatment material that exhibits excellent paint film adhesion and post-painting corrosion resistance. It is useful as the outer panel of a building or as a variety of building materials. The substrates to which the present invention is applied include those whose surface or material is Zn, Zn alloy, Fe or Fa.
In addition to gold alloys, nonferrous metals such as Ti, Ni, Co, Cu, and AI, and their alloys, as well as various ceramics such as silica glass and alumina, are included, and their shapes include plates and corrugated sheets. Although it does not matter whether the material is a pipe material, a bar material, etc., the following explanation will mainly be based on a typical steel plate.

[Prior Art] Steel plates used for the above-mentioned purposes are usually coated for the purpose of improving their appearance and corrosion resistance. Also Zn
Although Zn-based alloy plated steel sheets have excellent corrosion resistance, these plated steel sheets are often ultimately used after being painted.

However, when paints are applied directly to these steel plates, the adhesion of the paint film to the steel plates cannot be sufficiently improved. Therefore, pre-painting treatments such as phosphate treatment and chromate treatment are carried out as measures to improve adhesion, but even then, it cannot be said that the paint film adhesion is necessarily sufficient, and the corrosion resistance after painting does not fully meet the needs of users. This has not yet been achieved.

Furthermore, if a suitable amount of organic polymer is present on the surface of a steel sheet before applying a paint, not only will the paint become more compatible, but the organic materials will also bond with each other, significantly increasing the adhesion of the paint film. However, when considering corrosion resistance after painting, it may not be possible to maintain strong bonding strength especially in severe corrosive environments, and some materials may lose their corrosion resistance within a relatively short period of time.

[Problems to be Solved by the Invention] The present invention has been made in view of the above circumstances, and its purpose is to provide a film with excellent paint film adhesion and excellent corrosion resistance for a long period of time even after painting. The aim is to provide a surface treatment material that can last for a long time.

[Means for Solving the Problems] The structure of the present invention that can solve the above problems is based on the structure of the present invention, in which a composite mating layer containing an organic polymer of 0.01% by weight or more in terms of C content is formed on the surface of a base material. , which is coated with a silane coupling agent and has improved coating properties and post-coating corrosion resistance. Furthermore, in the present invention, an organic polymer is applied to the surface of the base material at an occupied area ratio of 0.
．． The objective can also be achieved by depositing 1% or more and applying a silane coupling agent thereon.

[Function] As described above, in the present invention, a certain amount of organic polymer is present on the surface of the base material, a silane coupling agent is applied thereon, and the action of the organic polymer and the silane coupling agent causes the steel plate to be bonded to the base material. It improves the adhesion of the paint film and also improves the corrosion resistance after painting.

It is known that a silane coupling agent improves the adhesion between a steel plate and a coating film, and the mechanism is thought to be as follows. That is, the silane coupling agent is represented by the general formula %, where R represents an organic reactive group such as a vinyl group, an amino group, or an epoxy group. A hydrolysis reaction occurs as shown in

R5i (OCI(s) s+ 3H20→R51((
IH) 3+ 3CI+30'11 And this hydrolyzed product causes a bond as shown in the following formula, where the hydroxyl group of the coated steel plate is bonded to the steel plate, while the organic reactive group represented by R is the organic substance contained in the paint. Because it reacts with the polymer or bonds with it through hydrogen bonds, etc., the coating film and the steel plate adhere to each other through the silane coupling agent.

However, the adhesion of the coating film provided by the silane coupling agent alone cannot necessarily be said to be sufficient, and further improvement is particularly desired in terms of corrosion resistance after coating.

When we investigated the reason why the coating film adhesion and post-coating corrosion resistance were insufficient when a silane coupling agent was used, the following facts were confirmed. In other words, although the bonding force between the silane coupling agent and the coating film is sufficient, the bonding force between the silane coupling agent and the steel plate is not sufficient, and eventually peeling occurs at the interface between the silane coupling agent and the steel plate. The phenomenon becomes more likely to occur. That is, the bonding force at the interface is, as described above, "-〇-rusted steel plate or r-o-o-steel plate via the oxide layer on the surface of the steel plate" or r-0-H20 via the adsorbed water on the surface of the steel plate. It is thought that this can be enhanced by bonding such as "-(0)-steel plate", but these bonding forces are not strong and it is thought that the bond will be relatively easily broken and the adhesion will be lost in a corrosive environment. .

Therefore, we conducted various studies to increase the bonding strength between the silane coupling agent and the steel plate, and found that by making an organic polymer exist on the surface of the steel plate and bonding the silane coupling agent and the steel plate through the organic polymer, the bond between the silane coupling agent and the steel plate could be improved. It became clear that the bond could be firmly bonded. By the way, the bonding force of the above-mentioned "r-□-steel plate" which brings about the bond between the silane coupling agent and the steel plate is 100 to 200KJ1 mole,
ro-CJ, ro-OJ, ro-NJ, which brings about a bond between a functional group in an organic polymer and a silane coupling agent.
0-H...", 'O-sJ etc. 08 cover 300-6
00 KJ/mol, and it can be confirmed that the binding strength in the latter case is extremely high.

As a result, the steel plates are firmly bonded via the organic polymer and the silane coupling agent, and the adhesion and post-painting corrosion resistance are significantly improved. However, in order to effectively exert the above-mentioned bond strength strengthening effect of the organic polymer, if the organic polymer is present on the surface layer by composite plating as described below, C
At least 0.01% by weight of the organic polymer must be present; if it is less than 0.01% by weight, a satisfactory bond-strengthening effect will not be exhibited. For example, in Figure 1, the base material is a steel plate, the organic polymer is an acrylic polymer,
Zn is used as the composite plating metal (electrodeposition eutectoid method is adopted as the 1st plating method), epoxy-based silane coupling agent is used as the silane coupling agent, and alkyd is used as the paint.
This is a graph showing the relationship between the organic polymer content (C equivalent amount) in the composite plating layer and the coating peeling width (crosscut SST, tape peeling test after 24 hours) using a melamine-based baking paint. By containing 0.01% by weight or more of the organic polymer in the composite surface layer, the effect of increasing the bonding strength is remarkable.

On the other hand, when an organic polymer is attached to the surface of a substrate by spraying or the like, the amount of the organic polymer attached must be adjusted so that the area ratio of the organic polymer to the surface of the substrate is 0.1% or more. For example, Figure 2 shows a case where a Ti plate is used as the base material, an acrylic polymer is attached as an organic polymer by JIB, an epoxy-based silane coupling agent is applied to this, an alkyd-modified melamine resin paint is applied, and then baked. Regarding the occupied area ratio of acrylic polymer deposited by the eruption and the width of paint film peeling (same as before)
This is a graph showing the relationship, and it can be seen that the effect of increasing the bonding force clearly appears by increasing the occupied area ratio of the organic polymer to 0.1% or more.

The organic polymer used in the present invention may be of any type as long as it can firmly bond to the silane coupling agent and the steel plate as described above, but it is preferable that the organic polymer has amino acids in its constituent molecules. It has a functional group having N, S, O, H, such as a group, an amide group, a sulfonic acid group, or a methylol group, and preferably has a molecular weight of 1000 or more.

In addition, methods for applying organic polymer to the surface layer include methods such as applying it to the surface by spraying, composite plating, etc., but the most preferable method is to coexist the plating metal component and organic polymer in the plating bath. Let me,
This is a composite plating method in which a metal and an organic polymer are eutectoided into a plating layer using an electrodeposited eutectoid method or the like. With this method, the organic polymer is mixed into the plating layer and is bonded to the silane coupling agent at the surface exposed portion, thereby further increasing the bonding strength. In this case, the plating metal is Zn or Zn and Fe, Ni, Co, Sn.
When alloys such as , Cr, and Mo are used, they also exhibit their own excellent corrosion resistance, and the corrosion resistance after painting becomes even more excellent.

The silane coupling agent used in the present invention has an organic reactive group and a siloxane bond in the molecule as shown in the general formula above, and various types are commercially available. Any of these can be used, but among them, epoxy-based silane coupling agents and acrylic-based silane coupling agents are prized as the most effective in enhancing bonding strength. These silane coupling agents are preferably selected according to the type of paint and have a strong affinity for it.

There are also no restrictions on the type of paint applied to the surface treatment material of the present invention, and all organic solvent-based and water-based air-drying paints or baking-type paints can be used.Specifically, acrylic Examples include various resin-based resins, vinyl-based resins, melamine-based resins, alkyd resin-based resins, etc., and these may of course be modified with epoxy or the like.

[Example] After applying the organic polymer shown in Table 1 to the surface of the base material shown in Table 1, ・A silane coupling agent was applied, and an alkyd-modified melamine resin paint (trade name "Amilac-1000J" manufactured by Kansai Paint Co., Ltd.) was applied. was applied and dried (dry film thickness: approximately 20 μm).

In Table 1, the methods for applying the organic polymer to the surface are: No. 1.5 to 9 are spray adhesion methods to the surface of the substrate (the amount of organic polymer indicates the area ratio occupied by the adhering portion on the surface of the substrate); For Nos. 2 to 4, 11° and 12, a composite plating method using electrodeposited eutectoid (the amount of organic polymer indicates the content in the composite plating layer) was adopted, respectively.

The details of the organic polymer and silane coupling agent used are as follows.

(Organic polymer) Acrylic type: Seiko Chemical Co., Ltd., product name rS-540J Vinyl type: Seiko Chemical Co., Ltd., product name Company product name rKBM 4
03J Acrylic system: Nippon Unicar Co., Ltd., trade name rA-150J The coating properties and post-coating corrosion resistance of each of the obtained coating base materials were investigated, and the results shown in Table 1 were obtained. However, the performance evaluation method and evaluation criteria were as follows.

(Paintability) Primary paint adhesion: Paint film survival rate determined by tape peeling after the Erichsen test.

○: Paint film residual rate 95% or more △: Paint film residual rate 95-70% 1 , Paint film residual rate after subsequent tape removal O: Paint film residual rate 95% or more △: Paint film residual rate 95-70% ×: Paint film residual rate 70% or less 2 (Corrosion resistance after painting) Cross-cut SST test 24 hours Paint film peeling width due to subsequent tape peeling O: Paint film peeling width 1+m or less Δ: Paint film peeling width 1 to 2 mm ×: Paint film peeling width 2 mm or more 15 From Table 1, the following can be considered.

Experiments Nos. 011 to 9 are examples that satisfy the specified requirements of the present invention, and good results were obtained in both paintability and post-painting corrosion resistance.

Experiment No. 10.12.13 is a comparative example in which organic polymer does not exist or is insufficient on the surface of the base material, and coating 1
The secondary adhesion is good, but the secondary adhesion is poor, and the corrosion resistance after painting is also very poor.

Experiment No. 11 is a comparative example in which no silane coupling agent was applied, and despite the presence of a sufficient amount of organic polymer on the surface of the base material, both the paintability and the corrosion resistance after painting were poor. .

Experiment No. 14 is a comparative example in which neither an organic polymer nor a silane coupling agent was used, and both performances were poor.

[Effects of the Invention] The present invention is configured as described above, and by applying the silane coupling agent to the surface layer of the base material via an organic polymer, the bonding force between the base material and the silane coupling agent is significantly increased. As a result, it has become possible to increase the adhesion of various paints and to significantly improve the corrosion resistance after painting.

[Brief explanation of drawings]

Figure 1 is a graph showing the relationship between the content of organic polymer in the composite plating layer and the width of paint peeling, and Figure 2 is a graph showing the relationship between the area occupied by the organic polymer sprayed onto the surface and the width of paint peeling. It is a graph.

Claims (2)

[Claims] (1) Paintability and post-painting corrosion resistance characterized by applying a silane coupling agent to the surface of a base material on which a composite plating layer containing an organic polymer of 0.01% by weight or more in terms of C content is formed. Excellent surface treatment material. (2) Paintability and coating characterized by applying a silane coupling agent to the surface of a base material to which an organic polymer is attached such that the area occupied by the base material surface is 0.1% or more. Surface treated material with excellent post-corrosion resistance.