JPS61255835A - Method for corrosion-proof surface coating of metal material - Google Patents

Abstract

PURPOSE:To provide a method for corrosion-proof surface coating of a metal material requiring no heating, by providing a reactive curable resin layer to the surface of the metal material and laminating a polyolefin cover sheet having an epoxy resin cured layer to said resin layer so that the epoxy resin cured layer is opposed to the reactive curable resin layer before adhering both layers by curing. CONSTITUTION:A reactive curable resin layer 12 is provided to the surface of a metal material 1 and a polyolefin cover sheet 14 having an epoxy resin cured layer 13 is separately prepared to laminate the polyolefin cover sheet 14 to the metal material 11 under pressure so that the epoxy resin cured layer 13 is opposed to the reactive curable resin layer 12 and the curing reaction of the reactive curable resin layer 12 held to an uncured state is completed to perform the adhesion of said resin layer 12 to the surface of the polyolefin cover sheet 14. Because no heating is required, there is no thermal deterioration of the polyolefin cover sheet and effective corrosion-proof coating can be applied even to the surface of the metal material difficult to sufficiently heat.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of the Invention] The present invention relates to a method for anticorrosion coating the surface of metal materials including steel materials such as steel sheet piles, steel pipe piles, and steel pipes.

[Background of the Invention] For the purpose of preventing corrosion on the surface of metal materials such as steel or aluminum pipes or plate-shaped molded bodies, adhesive coating of a plastic coating sheet such as a polyolefin coating sheet on the surface has already been practiced.

In particular, steel sheet piles or steel pipe piles are often used in contact with seawater for purposes such as seawalls, and are required to have long-term durability under such harsh conditions. It is used with anti-corrosion coating with polyolefin layer.

Generally, a sheet or film made of polyolefin resin or the like is used for such anti-corrosion coating. However, since polyolefins do not have polar groups and have poor adhesion to metal materials, adhesives containing polar groups such as maleated modified polyolefins that develop adhesion to metal materials when heated Polyolefin coated sheets are commonly used as coating materials, with layers pre-disposed on one side of the polyolefin sheet and laminated. Such a polyolefin coated sheet is attached to the surface to be coated with anticorrosion by heating and fusing it. Attaching the polyolefin coated sheet as described above is generally done in a factory because it requires heating during attachment.
・ However, depending on the shape of the object to be coated with anti-corrosion, there are some cases where it is not possible to apply effective anti-corrosion coating in advance in the factory, and welding parts, including exposed steel pipe surfaces near the welded parts, may not be coated after welding at the work site. Anti-corrosion coated. Furthermore, as a matter of course, it is common to repair damaged portions of the anticorrosion coating layer at the location where the damage occurred.

[Prior art and its problems] The anticorrosive coating method for metal materials using the polyolefin coated sheet as described above is, for example, a polyolefin coated sheet formed by laminating and fusing a heat-melting adhesive layer on one side of a polyolefin sheet. The adhesive layer is placed in contact with the surface to be coated with anti-corrosion coating such as steel, and the polyolefin surface of this polyolefin-coated sheet is heated directly using the flame of a gas burner or hot air to form an adhesive layer that is in contact with the surface to be coated with anti-corrosion coating. This is carried out by methods such as softening the agent layer and heat-pressing it.

The above anti-corrosion coating method requires almost no other tools as long as you have a gas burner or a heat source that generates hot air, and the work is extremely simple. This method is widely used because it can be easily performed on-site.

However, the method described above directly heats the surface of the polyolefin-coated sheet to soften the heat-melting adhesive layer on the backside to a bondable state, so this heating may cause thermal deterioration of the surface of the polyolefin-coated sheet. There's a problem.

Furthermore, if the above method is applied to covering steel pipe piles or steel sheet piles driven on the coast, for example, even if heated, the adhesive layer will be cooled by seawater and softened to a point where it can be bonded. There is also the problem that it is often not possible to install the device effectively.

On the other hand, various improvements have been proposed regarding the adhesive component of polyolefin-coated sheets.

For example, the main feature of JP-A-56-143223 and JP-A-56-117642 is that an epoxy resin is applied to the surface of a metal material in advance and a modified polyolefin or polyolefin layer is heat-adhered thereto. An invention is disclosed. These methods do not require direct heating of the surface of the polyolefin layer, so the problem of thermal deterioration of the polyolefin is solved, but the metal material must be heated to about 150°C in advance, and therefore Even with these methods, the problem of not being able to effectively apply the anti-corrosion coating material still remains unsolved under conditions where sufficient heating cannot be performed as described above.

[Object of the Invention] The present invention is characterized in that it provides a method for anti-corrosion coating on the surface of metal materials that does not particularly require heating. It is an object of the present invention to provide a method for attaching a sheet without particularly requiring heating.

[Summary of the Invention] The present invention provides a reaction-curable resin layer attached to the surface of a metal material, and a polyolefin-coated sheet having an epoxy resin cured layer on the reaction-curable resin layer. Provided is a method for anticorrosive coating on the surface of a metal material, characterized in that after laminating the curable resin layer so as to face it, curing of the reaction curable resin layer is completed and a polyolefin coating sheet is adhered.

Adhesion between the cured epoxy resin layer provided on the polyolefin-covered sheet and the reaction-curable resin layer attached to the surface of the metal material can also be achieved by interposing a reaction-curable resin intermediate layer therebetween.

[Effects of the Invention] By utilizing the present invention, an effective anticorrosion coating can be applied even to the surface of a metal material that is difficult to heat sufficiently.

Furthermore, since no particular heating is required when applying the anticorrosion coating, there is no thermal deterioration of the polyolefin coated sheet due to heating, and the anticorrosion property is good.

[Detailed Description of the Invention] The attached FIG. 1 is a diagram showing an example of an embodiment in which the surface of a metal material is coated with an anticorrosion coating according to the anticorrosion coating method of the present invention.

Basically, the present invention first attaches a reaction-curing resin layer 12 to the surface of a metal material 11 (surface to be coated with anti-corrosion), and separately prepares a polyolefin coating sheet 14 having a cured epoxy resin layer 13. After laminating the polyolefin-coated sheet 14 under pressure so that the epoxy resin cured layer 13 faces the reaction-curable resin layer 12, the curing reaction of the uncured reaction-curable resin 12 is completed, and the polyolefin-coated sheet ) 14 is an anticorrosive coating method that adheres to the surface.

The metal material to which the anti-corrosion coating is applied is not particularly limited as long as it requires an anti-corrosion coating during use; examples of such metal materials include:

Mention may be made of metal products made of iron, aluminum or zinc. In particular, the present invention is suitable for anticorrosive coating of iron steel pipe piles, steel sheet piles, and steel pipes. As mentioned above, parts of steel pipe piles and sheet piles used for seawalls, etc. that come into contact with seawater are cooled by seawater, so conventional methods that include heating operations do not effectively heat them. cannot be done, so in this case,
The anticorrosion coating method of the present invention is particularly useful.

Other anti-corrosion coatings, such as polyolefin anti-corrosion coatings, may be applied in advance around the area to be anti-corrosion coated.

The polyolefin-coated sheet used has an epoxy resin cured layer.

Epoxy resin is an adhesive with good weather resistance and exhibits excellent adhesion to metal materials, so it can be advantageously used as an anticorrosion coating. It does not show sufficient adhesion to sheets at room temperature. Therefore, when trying to take advantage of the excellent weather resistance of epoxy resin,
In the conventional method, it was necessary to apply an epoxy resin to the surface of a metal material, place an anti-corrosion coating sheet on the applied layer, and then heat and bond them together. However, in this method, sufficient adhesion cannot be achieved under conditions where sufficient heating cannot be performed, and the objective of providing excellent corrosion resistance over a long period of time cannot be achieved.

In contrast, the present invention is a method of using a polyolefin-coated sheet, which is an integrated polyolefin-coated sheet on which a cured epoxy resin layer is laminated in advance, as an anti-corrosion coating material, and the polyolefin-coated sheet is coated with polyolefin without the need for heating for adhesion of the epoxy resin. This is a method in which a sheet is attached to the surface of a metal material to be protected against corrosion.

Although a molded modified polyolefin sheet may be used as the polyolefin-coated sheet, generally a modified polyolefin layer 16 is laminated on the surface of an unmodified polyolefin sheet 15. In the latter case, a cured epoxy resin layer 13 is laminated on the modified polyolefin layer.

As the unmodified polyolefin sheet, those used as ordinary anticorrosion coating materials can be used. Examples of materials include low density polyethylene, medium density polyethylene, high density polyethylene, polypropylene, poly-1-
Olefin homopolymers such as butene and poly-4-methyl-1-butene, ethylene-propylene copolymers, ethylene + 11-butene copolymers, propylene-l
- Olefin copolymers such as butene copolymers, ethylene/vinyl acetate copolymers, and ethylene/acrylic acid ester copolymers, as well as olefin homopolymers or olefin copolymers obtained by crosslinking these olefin homopolymers or olefin copolymers by known methods. Examples include polymeric substances that can be used.

Sheets formed from unmodified polyolefins such as those described above are known to have high weather resistance. In particular, polyolefin sheets containing polyethylene as a main component are advantageous because they have good weather resistance and are inexpensive.

Examples of polymers forming the modified polyolefin layer include polyolefins grafted with unsaturated carboxylic acids (e.g., maleic acid, itaconic acid) or their anhydrides, and polyolefins grafted with unsaturated bonds and epoxy groups. Examples include polymers graft-modified with monomers contained in the molecule (eg, vinyl glycidyl ether, acrylic glycidyl ether, vinyl glycidyl thioether, glycidyl acrylate, glycidyl methacrylate, p-glycidyl styrene). In particular, it is preferable to use polyethylene graft-modified using maleic acid or its anhydride.

Examples of epoxy resins that form the epoxy resin cured layer include bisphenol A with an epoxy equivalent of 170 to 280.
Examples include epoxy resins formed from a base resin and an organic polyamine curing agent having an amine value of 200 to 500. Examples of the above-mentioned organic polyamine curing agents include modified aliphatic polyamines, modified aromatic polyamines, and heterocyclic modified polyamines. These can be used alone or in combination. For example, in consideration of weather resistance, it is preferable to use a heterocyclic modified polyamine. However, in consideration of the balance between adhesion to modified polyolefins and reaction-curing resins described later and the above-mentioned weather resistance, it is preferable to use modified aliphatic polyamines. is often preferred, therefore modified aliphatic polyamines are generally used.

Examples of modified aliphatic polyamines include: can be mentioned.

The ratio of the amount of the bisphenol A base agent to the organic polyamine curing agent used can be determined according to a conventional method.

When forming a polyolefin-coated sheet with a modified polyolefin layer on an unmodified polyolefin sheet, the thickness of the unmodified polyolefin sheet is generally 0.2 to 1.
0 mm, preferably in the range of 1 to 4 mm, and the thickness of the modified polyolefin layer is in the range of 0.05 to 5 mm, preferably 0.
．． It ranges from 1 to 3-5 mm.

When the polyolefin coated sheet is made of a molded product of modified polyolefin, its thickness is generally 0.3 to 10
mm, preferably in the range of 1 to 4 mm (F).

The thickness of the epoxy resin cured layer is in the range of 3 to 100 ILm, preferably 10 to 50ILm.

The production of such a polyolefin-coated sheet and the attachment of a cured epoxy resin layer are generally carried out by the following method.

For example, first, a modified polyolefin layer is attached to the surface of an unmodified polyolefin sheet such as a polyethylene sheet by a known method.

In addition, when using a crosslinked unmodified polyolefin sheet, it is also possible to laminate a modified polyolefin on a polyolefin sheet that has been crosslinked in advance, or a crosslinking operation may be performed after lamination.

Brush coating on the modified polyolefin layer of the laminated sheet (polyolefin coated sheet) obtained as above.
After applying an uncured epoxy resin using spray coating or a bar coater, the laminate sheet is heated to a temperature higher than the melting point of the modified polyolefin in the modified polyolefin layer of the laminate sheet to harden the epoxy resin while softening the modified polyolefin layer. Alternatively, an epoxy resin is applied by the above method to a laminated sheet heated to a temperature below the melting point, and while the epoxy resin is cured, the modified polyolefin layer and the epoxy resin are integrated to form a polyolefin-coated sheet having a cured epoxy resin layer. do.

The above-mentioned heating can be carried out according to the prior art. For example, it is also possible to use an infrared heater, etc., but in order to more firmly adhere and integrate the laminated layers, it is necessary to use, for example, a heating roll or It is preferable to heat the sheet under pressure using a hot press or the like. When using a hot roll or a hot press, it is preferable to use Teflon or the like on the contact surface with the sheet to impart releasability.

Even when using a sheet made only of modified polyolefin, it can be produced according to the above method.

It goes without saying that the polyolefin (modified or unmodified) sheet may contain additives that are normally contained (eg, antioxidants, pigments, and other additives).

The polyolefin coated sheet produced in this manner is placed on the reaction-curable resin layer 12 formed on the surface of the metal material 11 to be coated with anti-corrosion, so that the epoxy resin cured layer 13 and the reaction-curable resin layer 12 are facing each other. Laminating and bonding are carried out in such a manner that the bonding is normally carried out under pressure.

The reaction-curing resin layer can be applied in accordance with the usual method of coating on the metal material to be coated with corrosion protection using methods such as brushing or spray coating.The thickness of the reaction-curing resin layer is as follows: , generally 3 to 1100 IL, preferably 10 to 501 Lm.

As the resin forming the reaction-curable resin layer, a resin having adhesive properties with the epoxy resin cured layer is used. Further, as a matter of course, the resin has adhesive properties with metal materials.

Therefore, it is preferable to use an epoxy resin as the reaction-curable resin, and it is particularly preferable to use the same epoxy resin as that used in forming the above-mentioned epoxy resin cured layer. When a modified aliphatic polyamine curing agent is used as a curing agent, the adhesion to the cured epoxy resin layer of the polyolefin-coated sheet is often particularly good.

When a bisphenol A-based main agent and an organic polyamine curing agent are used, the ratio of the amounts used can be determined in accordance with the prior art in the same manner as described above.

Note that a polyurethane resin can also be used as the reaction-curable resin. However, in this case, it is not necessary to interpose a reaction-curing resin intermediate layer, which will be described later.

The above-mentioned reaction-curing resin layer must be uncured at the time of the lamination operation, or at least the curing reaction must not be completed. Loses adhesive ability at room temperature.

There are no particular restrictions on the method of laminating the polyolefin-coated sheet onto the reaction-curable resin layer, and a normal method may be used, such as using an elastic member to press and adhere the polyolefin-coated sheet to the surface to be coated with anti-corrosion coating. I can do it.

Although the present invention does not require heating, the surface of the polyolefin-coated sheet may be heated to, for example, about 50 to 60°C in order to accelerate curing.

The polyolefin-covered sheet having the epoxy resin cured layer laminated in contact with the reaction-curable resin layer is thus integrated with strong adhesion upon completion of curing of the reaction-curable resin.

In this manner, the present invention allows the polyolefin-coated sheet to be attached without any particular heating.

Not only does it have good corrosion resistance, but it also has particularly good adhesion by interposing a reaction-curing resin intermediate layer between the cured epoxy resin layer and the reaction-curable resin layer of the above-mentioned polyolefin-coated sheet and laminating them under pressure. , corrosion resistance is further improved.

FIG. 2 is a diagram schematically showing an example in which a polyolefin coating sheet is attached via a reaction-curable resin intermediate layer.

In FIG. 2, the metal material is indicated by 21, and the reactive hardening resin layer is indicated by 22. In addition, the epoxy resin cured layer is 23
The polyolefin-coated sheet is designated by 24.

The unmodified polyolefin sheet constituting the polyolefin coated sheet is indicated by 25, and the modified polyolefin layer is indicated by 2.
6.

That is, in the configuration shown in FIG. 2, a reaction curable resin intermediate layer 27 is interposed between the reaction curable resin layer 22 and the epoxy resin cured layer 23.

Also in the method of interposing a reaction-curable resin intermediate layer, the polyolefin-covered sheet described above can be used. However, as an organic polyamine curing agent for the epoxy resin curing layer attached to the polyolefin coated sheet,
In particular, it is preferable to use a heterocyclic modified polyamine described below.

The resin forming the reaction-curable resin layer attached to the surface of the metal material can be substantially the same as the above-mentioned epoxy resin. However, since the reaction-curing resin intermediate layer is interposed between the reaction-curing resin layer and the cured epoxy resin layer, the adhesion of one reaction-curing resin layer to the resin forming the reaction-curing resin intermediate layer must be considered. For example, there is no need to particularly consider adhesion with the cured epoxy resin layer.Therefore, heterocyclic modified polyamines or aromatic modified polyamines that produce epoxy resins with excellent weather resistance can be used as raw organic polyamines. It has the advantage of

Examples of heterocyclic modified polyamines include:

Examples of aromatic modified polyamines include can be mentioned.

As the resin forming the reaction-curable resin intermediate layer, a resin having substantial adhesion to both the epoxy resin cured layer and the reaction-curable resin layer is used.

Examples of resins used include epoxy resins and polyurethane resins. In particular, it is preferable to use polyurethane resin. Ordinary polyurethane resins can be used.

When using an epoxy resin as the material for the intermediate layer, it is necessary to select and use a resin that has good adhesion to both the epoxy resin cured layer and the reaction-curable resin layer.

A method for interposing the reaction-curable resin intermediate layer between the epoxy resin cured layer and the reaction-curable resin cured layer is to apply it onto the reaction-curable resin layer attached to the surface of the metal material before the curing reaction is completed. It is also possible to use the method,
Generally, a method of coating on the cured epoxy resin layer on the coating sheet side is used.

Note that the reaction-curable resin intermediate layer coated on the polyolefin-coated sheet is usually laminated and adhered onto the reaction-curable resin layer in an uncured state. However, it does not always need to be uncured; the reaction-curing resin layer is in an uncured state, so even if the reaction-curing resin intermediate layer is cured, it will adhere firmly and have good weather resistance. That is, instead of the reaction-curable resin intermediate layer described above, a cured resin intermediate layer, such as a cured polyurethane resin, can also be used.

However, when using the method of coating on the reaction-curing resin layer, the polyolefin is Laminate and adhere the covering sheets.

The thickness of the reaction-curable resin intermediate layer ranges from 3 to 200 m, preferably from lO to 1100 JL.

Next, examples of the present invention will be shown.

[Example 1] Low density polyethylene with a thickness of 2 mm (MI: 0.1g71
Maleated polyethylene (MI: 1, 5 g/l 0 min, density: 0.92) was coated on the surface of a sheet (carbon concentration: 2.5 wt%) of
2 g/cm'', maleation equivalent: IXI O-% mol/
A modified polyolefin layer made of (gPE) was attached by T-die molding to a layer thickness of 0.5 mm.

On this maleated polyethylene layer, an epoxy resin consisting of bisphenol A type (epoxy equivalent, 190) and aliphatic modified polyamine (manufactured by Yuka Shell Epoxy ■, Epocure-3012) is uniformly applied to a thickness of about 30 pm using an airless gun. After coating, using a large press machine with a Teflon sheet for mold release pasted on the surface of an 80 x 500 cm hot plate, the temperature was 160°C, the pressure was 0, and the pressure was 1 kg/crn'c7).
After pressurizing for 3 minutes under these conditions, it was cooled and then heated to 80×16
A polyethylene sheet (polyolefin-coated sheet) having an epoxy resin cured layer was produced by cutting into 0 cm pieces.

Steel pipe piles (diameter 508 m) attached to imitate the foundation piles of the pier
After sandblasting the surface of the part corresponding to the tidal zone splash zone (wall thickness: 9 mm), apply the same epoxy resin as above to a thickness of about 40 mm, and immediately apply the above The anticorrosive coating sheets were laminated so that the cured epoxy resin layer and the uncured epoxy resin layer faced each other, and were temporarily fixed with a rubber belt.

Note that a gap of about 2H was created at the abutting portion of the anticorrosive coating sheet, but the joint was sealed using a polysulfide elastic sealant.

The maximum temperature on the day of construction was about 30°C, and the epoxy resin, which is a reactive hardening resin, hardened and began to develop adhesive strength in about 24 hours.

After 48 hours, the beer strength of the anticorrosive coating sheet was measured. When the beer strength reached approximately 15 kg/cm, interfacial peeling occurred between the cured epoxy resin layer and the maleated polyethylene layer.

Steel pipe piles with anti-corrosion coating were left exposed to splash zone and tidal zone for two years.

Two years later, when observed, there was almost no change in the appearance, and when the beer strength was measured under the same conditions as above, it was about 14 kg/cm.

No rust was observed on the surface of the steel pipe pile that was removed to measure beer strength.

[Example 2] In Example 1, a heterocyclic modified amine (manufactured by Yuka Shell Epoxy ■, Epomate B-001, amine value: :280), and then apply a polyurethane prepolymer (manufactured by Dai-ichi Kogyo Yakuhin ■, trade name: MacFlew 350u) to a thickness of about 30 JLm on the epoxy resin cured layer of the polyethylene sheet, and combine this polyurethane prepolymer with A steel pipe pile was coated with anti-corrosion in the same manner except that the epoxy uncured resin layer (reactive hardening resin layer) was placed facing each other.

The highest temperature on day a of construction was about 30° C., and the epoxy resin, which is a reaction-curable resin, hardened and began to develop adhesive strength in about 24 hours.

After 48 hours, the beer strength (beer strength) of one sheet of anticorrosion coating material was measured and was found to be approximately 7 kg/cm.

The steel pipe pile provided with the anti-corrosion coating was left for two years under the same conditions as in Example 1.

Two years later, when observed, there was almost no change in the appearance, and when beer strength was measured under the same conditions as above,
It was about 6 kg/cm.

No rust was observed on the surface of the steel pipe pile that was removed to measure beer strength.

[Brief explanation of drawings]

FIG. 1 is a diagram schematically showing an example of an embodiment in which an anticorrosive coating sheet is attached to the surface of a metal material. FIG. 2 is a diagram schematically showing another embodiment in which an anticorrosive coating sheet is attached to the surface of a metal material. ll: Metal material, 12: Reaction curable resin layer, 13: Epoxy resin cured layer, 14: Polyolefin coating sheet), 1
5: Unmodified polyolefin sheet, 16: Modified polyolefin layer 21: Metal material, 22: Reactive curable resin layer, 23: Epoxy resin cured layer, 24: Polyolefin coated sheet, 2
5: Unmodified polyolefin sheet, 26: Modified polyolefin layer, 27: Reactive hardening, oxidizing resin intermediate layer

Claims (1)

[Claims] 1. A reaction-curable resin layer is attached to the surface of the metal material, and a polyolefin-covered sheet having an epoxy resin cured layer is placed on the reaction-curable resin layer, and the epoxy resin cured layer is reaction-cured. 1. A method for anticorrosive coating on the surface of a metal material, which comprises laminating the reaction-curable resin layer so as to face it, and then completing the curing of the reaction-curable resin layer and adhering a polyolefin coating sheet. 2. A patent characterized in that the epoxy resin cured layer provided on the polyolefin coated sheet and the reaction curable resin layer attached to the surface of the metal material are bonded by interposing a reaction curable resin intermediate layer therebetween. A method for anticorrosive coating on the surface of a metal material according to claim 1. 3. Claim 1, characterized in that the polyolefin coated sheet is composed of an unmodified polyolefin layer and a modified polyolefin layer, and the epoxy resin cured layer is laminated on the modified polyolefin layer. Alternatively, the method for anticorrosion coating on the surface of a metal material according to item 2. 4. The method for anticorrosive coating of a surface of a metal material according to claim 1 or 2, wherein the polyolefin coating sheet is a molded product of modified polyolefin. 5. The method for anti-corrosion coating on the surface of a metal material according to claim 3 or 4, wherein the modified polyolefin is a maleic acid-modified polyolefin. 6. The method for anti-corrosion coating on the surface of a metal material according to claim 1 or 2, wherein the epoxy resin cured layer is formed of a cured product of bisphenol A and modified aliphatic polyamine. 7. The method for anti-corrosion coating on the surface of a metal material according to claim 1 or 2, wherein the resin forming the reaction-curable resin layer is a two-component curable epoxy resin.