JPS5920077B2 - Anti-corrosion coated metal pipe - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an anti-corrosion coated metal tube with excellent anti-corrosion properties and impact resistance.

More specifically, it is an anti-corrosion coated metal that forms a strong mastic-type coating layer on the outer surface of the metal pipe by automatically spraying and dispersing a specified reinforcing material at the same time as anti-corrosion coating using a rotary coating method etc. It is related to pipes.

Since ancient times, the coating of metal pipes, especially steel pipes, has been carried out with coal tar enamel, asphalt and asphalt enamel, which have low hardening, embrittlement, impact resistance,
Physical properties such as flexibility and adhesion are insufficient, causing trouble.

In addition, this kind of bituminous material has disadvantages such as heating and melting during coating, which requires skill, and the production of an irritating gas odor.

In addition, as a paint type, tar epoxy paints that are used in the past have a slow curing speed and require a long time to dry after painting, which greatly impedes the painting speed and reduces painting efficiency and economics. It has a negative impact on sexuality.

Therefore, the inventors of the present invention decided to eliminate these drawbacks (after various studies), based on a urethane resin that has excellent low-temperature properties and is quick to cure and dry, and blended with petroleum resin,
Furthermore, by coating the outer surface of the metal tube with a corrosion-proofing agent and reinforcing material containing appropriate pigments, fillers, etc., we succeeded in developing a corrosion-proof coated metal tube with excellent properties.

The fast-curing drying type urethane resin referred to in this invention is one in which an amine-based curing agent is blended with an isocyanate prepolymer. The group content is 3 to 10 units.

For example, Orester LP2309 or XQ-2746LP manufactured by Mitsui Toatsu Kagaku (■) is suitable.

Petroleum resins are polymers of C2 to C15 hydrocarbon fractions that are heated and polymerized using petroleum unsaturated hydrocarbons directly as raw materials using suitable catalysts. Suitable are Cainton manufactured by Esso Standard, Picolate Ink manufactured by Esso Standard ■, Turclon manufactured by Yoshida Oil ■, or Shintalon manufactured by Tokyo Jushi ■.

The anticorrosive material has the above-mentioned quick-curing drying urethane resin and petroleum resin as main components, but subcomponents such as pigments and fillers may be added as necessary.

Examples of pigments include carbon, Fe2O3゜TiO
For example, talc, silica, mica, etc. can be used as a filler.

Incyanate prepolymer (hereinafter referred to as the first component), amine curing agent, petroleum resin, and the above-mentioned subcomponents (hereinafter referred to as the second component) are sprayed or painted (for example, airless spray painting). ) is mixed and applied immediately before application.

Almost at the same time, one or more of silica sand, blast furnace slag, or solid particulate synthetic or natural resins as a reinforcing material is sprayed singly or in a mixture to the surface layer of the anticorrosive material consisting of the first component and the second component. After 1 to 2 minutes, the mixed material layer of reinforcing material and anticorrosive material is formed and then dried and hardened to the extent that it can be treated as a film.

As the incyanate prepolymer as the first component in this invention, a commercially available incyanate prepolymer having an isocyanate group content of 3 to IO% is used.

As the amine curing agent in the second component, for example, OLESTAR XQ-2747AD manufactured by Mitsui Toatsu Chemical Company.

Alternatively, XQ-2310AD may be used, and the amount thereof may range from 25 to 38% by weight based on 100 parts by weight of the gin polymer.

In addition, petroleum resin, pigment, filler, etc. are used as described above, but the amounts are generally 25 to 40% by weight of petroleum resin, 1 to 5% by weight of pigment, and 20 to 45% by weight of filler. However, this amount is not particularly limited and further pigments and fillers may not be necessary.

By mixing a petroleum resin with a quick curing drying type urethane resin, the following effects can be achieved.

That is, since the petroleum resin has good compatibility with the curing agent, it is possible to reduce the influence on the properties of the cured resin due to errors in the blending ratio, etc.

Since a large amount of petroleum resin can be used as an extender, it is possible to significantly reduce costs.

Petroleum resins can be used in the same manner as bitumen, such as coal tar, to produce inexpensive colored hardened resins.

It has good workability and extremely low loss on heating, so an excellent cured resin with little change over time can be obtained.

Furthermore, since the anticorrosive coating film has excellent flexibility due to the inclusion of petroleum resin, an anticorrosive coated metal pipe with good impact resistance, water resistance, weather resistance, and cold resistance can be obtained.

The blending amount of this petroleum resin is not particularly limited.

However, if the petroleum resin component is less than 25%, water resistance tends to be poor, and if it is more than 40%, cold resistance and coating flexibility tend to be poor.

The amounts of the first component and the second component to be blended are naturally determined by the isocyanate group content in the first component and the amount of the amine curing agent in the second component.

Next, in order to investigate the characteristics of the urethane resin-based anticorrosive agent used in this invention, a material with the following composition was applied to the material to be coated using a three-way gun, and the amount was 250μ to 300μ.
Apply to a film thickness (dry) of 7.
Let dry for days.

First component 100.0 parts by weight of incyanate prepolymer and JIS tar epoxy paint for the sample.
When the characteristics were investigated according to the K-5664 standard, extremely good results were shown as shown below.

On the other hand, the reinforcing material can be selected as appropriate as long as it improves impact resistance, abrasion resistance, and film strength. Various options are conceivable, taking into account economic efficiency and the like.

Next, we will discuss the case of using blast furnace slag, for example. Blast furnace slag is discharged as slag from a molten blast furnace when making pig iron, and after cooling and solidifying it, it is prepared into a specified particle size using a crusher. use things

The components of blast furnace slag are mostly 5i0225-40, At20
Section 38-18, Ca032-45%, other Fe *
It includes Fe02 Mg Oe TI O2g Mn pP and the like.

Various grain sizes can be used for the blast furnace slag, depending on the desired film thickness, metal tube diameter, etc., but generally 10 to 150
A mesh size range is preferable.

Various types of crushed sand are used depending on the purpose, film thickness, etc., but it is generally considered to be No. 3 to No. 6 silica crushed sand.

In addition, in this invention, for the purpose of protecting the outer surface of the coated metal tube, a polyethylene sheet or tape is wrapped over the coating, or a glass cloth, chute, etc.
There are no restrictions on various types of external protection, such as impregnation with the urethane resin paint used in this invention and adhesion coating.

When applying the coating material, the temperature is determined using a so-called three-gun airless sprayer, in which a first component based on incyanate prepolymer and a second component containing an amine curing agent are mixed together from a separate system during application of L1. ℃ and apply to the desired material.

In addition, when applying to metal pipes such as steel pipes, it is preferable to perform blasting and primer treatment on the surface of the metal pipe in advance to improve adhesion, but primer treatment is not necessarily required.

It should be noted that mixing the first component and the second component in advance prior to coating is a quick curing and drying type that is the gist of the present invention.
Since the anticorrosive compound is set, reaction solidification will begin, so this cannot be used.

The reinforcing material is uniformly spread by a spreading method or the like before the anticorrosive material is dried and solidified as described above.

Therefore, the reinforcing material is uniformly distributed in the urethane-based corrosion protection material, and the corrosion protection material and the reinforcing material are mixed on the surface of the metal tube through the urethane-based corrosion protection layer with individual particles being bonded together by the corrosion protection layer. It exists as a material that forms a mixed material layer.

In actual painting work, a layer of corrosion protection alone is formed on the surface of the metal pipe, and then a mixed material containing a reinforcing material and a corrosion protection material is applied on top of this layer. It is desirable from the viewpoint of improving distribution uniformity, coating workability, film adhesion, and anticorrosion effect.

Next, the anti-corrosion coated metal tube of the present invention will be explained with reference to the embodiment shown in the figures. In FIG. In this case, a layer 4 of a mixed material of and a reinforcing material is applied, and in FIG. On top of this, a layer 4 of a mixed material of anti-corrosion and reinforcing material is applied.

Here, the boundary between the anticorrosive layer 3 and the mixed material layer 4 is as shown in the figure (although it is not clearly shown), the anticorrosion layer is first painted using a three-tube gun airless sprayer, and then the reinforcing material is applied. By spraying and coating, the mixed material layer 4 can be easily formed on the surface layer portion of the anticorrosive layer 30.

In this way, if the anticorrosive layer 3 is not used as the lower layer, the anticorrosive effect will be poor.
It becomes weaker.

Fig. 2 shows an example in which the anticorrosion effect is further improved, in which a corrosion-proofing layer 3 is applied to the outer surface of the metal tube 1 via a primer layer 2, and a layer 4 of a mixed material of corrosion-proofing material and reinforcing material is applied on the outer surface of the metal tube 1. administer,
Furthermore, an anticorrosion layer 3' is applied thereon.

As described above, according to the present invention, a corrosion-resistant coated metal that has excellent characteristics such as corrosion resistance, is inexpensive in terms of material because it uses an inexpensive material as a reinforcing material, and is also easy to work with because it has good dry hardening properties. Tubes can be provided.

Next, this invention will be explained using a specific example.

Example 1 The outer surface of a steel pipe (inner diameter 600 m) was descaled and cleaned by shot blasting, a commercially available urethane wash primer was thinly applied thereon, and the dried product was used as a supply pipe. Apply 500μ (wet film thickness) of a urethane resin anticorrosion compound of the composition shown in Table 1 below using a cylinder gun airless sprayer, and then immediately apply 30μ
Blast furnace slag adjusted to a range of ~100 mesh was uniformly spread and coated.

After that, 100% of the urethane resin-based anticorrosive material was applied again.
It was coated with oμ (wet film thickness) and dried at room temperature to obtain a urethane resin film containing a reinforcing material.

Such a coated steel pipe dries to the touch extremely quickly in 2 minutes, and can be moved and relocated after 15 minutes, making it possible to manufacture coated steel pipes extremely efficiently and rationally.

The coated steel pipe was left to cure at room temperature for 7 days, and an applied voltage of 1
A pinhole test was conducted at 0000V.

This coated steel pipe coating showed good results with no pinholes observed.

Thereafter, an underwater film insulation resistance test was conducted.

As a result, even after one year, extremely good insulation resistance of 10 Qtyn or more was exhibited.

Example 2 A steel pipe (with an inner diameter of 100,100 mm) was descaled and cleaned by shot blasting, a commercially available epoxy primer was applied thinly and dried, and then used as a test tube. A 700 μm (wet film thickness) urethane resin having the composition shown in Table 2 was applied by the method, and then commercially available No. 5 crushed sand or blast furnace slag was uniformly spread and coated.

After that, 800μ (w) of the urethane resin anticorrosion was applied again.
e (thickness)) and dried at room temperature.

The coated steel pipe was left at room temperature for 20 days, and then JI
Table 3 shows the results of the impact test specified in SG-3492.

The same table also lists the performance of steel pipes (4 to 6 in Table 2) coated with conventional asphalt-based or coal tar-based paints.

The numbers indicate the peeled area (c4).

As is clear from Table 3, the coated steel pipe according to the present invention has excellent impact resistance even in the low temperature range.

Test No. 2, which contains a large amount of petroleum resin, shows slightly inferior impact resistance, but is far superior to conventional asphalt-based or coal tar-based paints.

Example 3 The outer surface of a steel pipe (inner diameter 1200rrr!n) was descaled by shot blasting, a commercially available epoxy primer was applied thereon, and the dried product was used as a test pipe.
The outer surface of this steel pipe was first coated with 700 μm (we is film thickness) of urethane resin anticorrosion of Formulation Example 1 and Formulation Example 2 shown in Table 4 using a three-tube gun airless sprayer, and then commercially available No. 5 crushed sand was applied. Sprayed and coated as desired.

After that, apply the urethane resin anticorrosion coating again to 800 μm.
(Wet film thickness) coating and drying at room temperature.

The coated steel pipe was left at room temperature for 20 days, and then immersed in saline solution for 6 months, and the length of water immersion from the end face between the steel surface and the coating was measured.

The length of water infiltration from the end face of the steel pipe coated with the anticorrosive material of Formulation Example 1 was extremely good at 0 to 2 rran.
The length of water intrusion from the end surface of the steel pipe coated with the anticorrosive material of Formulation Example 2 was 7 to 15 rrrIn, and considerable water intrusion was observed.

This result shows that it is not preferable if the blending ratio of petroleum resin is too low.

In addition, when manufacturing the anti-corrosion coated metal tube of the present invention, the metal tube is placed on a turning roller device, and while the rotation speed is adjusted according to the outer diameter dimension, a fast-curing drying type urethane resin base is applied. A mastic coating layer of a desired thickness can be easily formed by spraying the anticorrosion and/or reinforcing material using a three-barrel gun airless sprayer or the like.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention, and FIG. 1 shows a corrosion-proof coated metal pipe in which a corrosion-proofing layer is applied to the outer surface of the metal pipe through a single layer of primer, and a layer of a mixture of corrosion-proofing material and reinforcing material is applied on top of this. FIG. 2 is a partial cross-sectional view of a corrosion-resistant coated metal tube in which an anti-corrosion layer is further applied on the mixed material layer shown in FIG. 1, and FIG. 3 is a partial cross-sectional view of the metal tube shown in FIG. FIG. 2 is a partial cross-sectional view of a corrosion-resistant coated metal tube with one layer of primer omitted. 1...metal tube, 2...primer layer,
3, 3'...Anti-corrosion layer, 4...A mixed material layer of recommended material and reinforcing material.

Claims (1)

[Scope of Claims] 1. A corrosion-proofing layer made of a corrosion-proofing material whose main components are a quick-curing drying urethane resin and a petroleum resin is formed on the outer surface of a metal tube,
It is characterized in that a mixed material layer is formed on the corrosion-proofing layer, which is a mixture of the corrosion-proofing material and a reinforcing material made of one or more of crushed sand, blast furnace slag, or solid particulate synthetic or natural resin. Anti-corrosion coated metal pipe. 2. Forming an anti-corrosion layer on the outer surface of the metal tube, which is made of an anti-corrosion material whose main components are a quick-curing drying urethane resin and a petroleum resin,
A mixed material layer made of a mixture of the corrosion-proofing material and a reinforcing material made of one or more of crushed sand, blast furnace slag, or solid particulate synthetic or natural resin is formed on the corrosion-proofing layer, and further the mixed material is formed on the corrosion-proofing layer. A corrosion-proof coated metal pipe, characterized in that a corrosion-proofing layer made of the corrosion-proofing material described above is formed on the layer.