JP2702164B2 - Corrosion resistant composite pipe - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a composite provided with anticorrosion measures for use in corrosive atmospheres such as urban sewer pipes, industrial sewer roads, hot spring drain pipes, and the like. About pipes.

[Conventional technology and its problems]

It is a well-known fact that concrete pipes, fume pipes, and asbestos pipes (hereinafter referred to as concrete pipes and the like) which are generally widely used in sewer pipes and the like have poor acid resistance and corrosion resistance. As a countermeasure against such a problem, an inner surface layer of a concrete pipe or the like is covered with a reinforced plastic (hereinafter, referred to as FRP) lining material.

However, the FRP lining material is difficult to eliminate through air bubbles, lacks the impregnation property of the matrix resin into the fiber reinforcement, and has a large chemical solution permeability, etc.
It is necessary to increase the thickness of the lining material more than necessary, which is economically disadvantageous.

In addition, since the impregnation operation cannot be performed, the content of the fiber reinforcing material must be suppressed to a low level. As a result, the strength of the lining material layer is insufficient, and there is a defect that a failure phenomenon such as a crack or a crack is likely to occur due to an external force such as an impact.

That is, when the FRP lining material is applied to concrete pipes, etc., the thickness of the FRP lining material is 3 mm (about 4200 g /
m ² ) or higher.

On the other hand, the flare lining material of the present invention has an extremely low chemical solution penetration rate as compared with the FRP lining material (for example, the water vapor permeability of the glass flare lining material is about 1/10 or less of the FRP material). In principle, it is possible to reduce the thickness of.

However, pin holes, cissing,
Due to poor construction or the like, a lining portion thinner than the designed thickness is easily formed, and it is difficult to find the lining portion.

An object of the present invention is to solve the above-mentioned problems of a corrosion-resistant composite pipe using a concrete pipe or the like as a base material, and to provide a high-quality corrosion-resistant composite pipe that can be manufactured at low cost.

[Means for solving the problem]

The inventor of the present invention has intensively studied to solve the above-mentioned problems, and as a result, it has been found that the lining of the flaking lining material, which has a substantially low penetration rate of the chemical solution, is thinned, and the defect of the flaking lining layer is caused by a commercially available pinhole tester (for example, It is effective to have a conductive primer layer having a volume resistivity of 10 ⁸ Ωcm or less, preferably 10 ⁶ Ωcm or less, which can be easily detected by a pinhole detector manufactured by Sanko Electronic Laboratory Co., Ltd. Heading, the present invention has been reached. The detected defective portion can be easily corrected by a conventional method such as a brush or a spatula.

That is, the present invention relates to a corrosion-resistant composite pipe in which a flaking material is lined on the inner surface of a concrete pipe, a fume pipe, or an asbestos pipe, and a volume resistivity of 10 ⁸ Ωcm or less between the inner face of the pipe and the flaking material layer. Is a corrosion-resistant composite pipe having a conductive primer layer interposed therebetween.

The primer layer in the present invention is made of a thermosetting resin of an unsaturated polyester resin, an epoxy resin, a vinyl ester resin or a urethane resin containing a conductive filler.

As the conductive filler, for example, graphite (graphite) powder, carbon powder, carbon whisker, carbon fiber, gold,
Examples include powder whiskers, fibers, flakes, cloths, and nonwoven fabrics of a single metal or alloy such as silver, copper, and aluminum, and one or more of these can be used.

The amount of the conductive filler in the primer is preferably in the range of not more than 10 ⁸ Ωcm, more preferably not more than 10 ⁶ Ωcm, and is empirically in the range of 3 to 40% by weight.

If the volume resistivity of the primer is 10 ⁸ Ωcm or less, it is difficult to detect a pinhole, cissing, poor construction, etc. of the flaking layer with a commercially available pinhole tester, which is below the design thickness.

As the thermosetting resin, an unsaturated polyester resin, an epoxy resin, a vinyl ester resin, and a urethane resin are used.

The unsaturated polyester resin is, for example, maleic acid, fumaric acid, itaconic acid, αβ unsaturated dibasic acid such as citraconic acid, or phthalic acid, isophthalic acid, terephthalic acid, succinic acid, and adipic acid if necessary and anhydrides thereof. Condensation reaction of esterification of dibasic acids such as Zebatic acid, Azelaic acid, Tetrahydrophthalic acid, Chlorendegic acid and glycols such as ethylene glycol, propylene glycol, propylene oxide, diethylene glycol, triethylene glycol and neopentyl glycol at room temperature The product is obtained by diluting and mixing a vinyl compound such as styrene, vinyltoluene, divinylbenzene, methyl methacrylate, and diallyl phthalate by about 20 to 50% by weight.

Epoxy resin is an epoxy compound having two or more epoxy groups in a molecule.
828, 1004, DEN431, 438 manufactured by Dow Chemical Company, and the like.

The epoxy resin may optionally contain a curing agent, for example, an amine compound having two or more amine groups, or a curing agent such as a polybasic acid anhydride.

As the amine compound, for example, Ciba-Geigy hardener HY951, 956, 974, etc., as polybasic acid anhydride,
For example, Ciba Geigy hardeners HT901, 903, 905 and the like can be mentioned.

The vinyl ester resin is, for example, 1.0 to 0.9 mol of acrylic acid per 1 mol of epoxy group of the epoxy resin,
An unsaturated monobasic acid such as methacrylic acid is subjected to an addition reaction by a conventional method, and a vinyl compound such as styrene, vinyltoluene, divinylbenzene, methyl methacrylate, or diallyl phthalate is diluted and mixed by about 20 to 50% by weight. .

The urethane resin is obtained by reacting a compound having two or more NCO groups in one molecule, for example, tolylene diisocyanate, hexamethylene diisocyanate, etc. with a polyester polyol having an OH group at the terminal and having a number average molecular weight of 500 to 10,000. Refers to the compound obtained.

Further, the conductive primer may contain a reinforcing material such as glass fiber, vinylon fiber and aramid fiber, a filler such as glass flake, mica, talc and clay, and a thixotropic additive such as ultrafine silica and asbestos powder. . The coating amount of the conductive primer layer is not particularly affect the present invention but is generally 10 to 500 g / m ^2, preferably 50 to 300 g /
m ² is good.

4 Also, epoxy resin,
An unsaturated polyester resin, a mixture of one or more vinyl ester resins, and a matrix component,
The main component is a flaky filler (a so-called flake agent) such as glass, mica, metal, or a mixture of two or more. In addition, known fillers such as calcium carbonate, silica, talc, clay, and aluminum hydroxide may be included.

Generally, the content of the flake agent is 5 to 60% by weight, preferably 10 to 40% by weight. The coating amount of the flaking material is 100 to 3000 g / m ² , preferably 500 to 2000 g / m ² .
No sufficient corrosion effect is less than the amount applied is 100g / m ^2, 3000g
If it exceeds / m ² , it is excessive and meaningless as a lining material for the purpose of corrosion resistance, and is expensive and disadvantageous in terms of price.

In order to manufacture the corrosion-resistant composite pipe of the present invention, the following method is typically given. That is, the conductive primer of the present invention is applied to the inner surface of a concrete pipe or the like with a sprayer, a brush, a roller, a spatula, or the like, and dried by heating with hot air, an infrared heater, or the like to the extent of dryness to the touch. Then, a flaking material may be similarly applied thereon by using a spray brush or the like, and then completely cured with hot air, an infrared heater, or the like.

〔Example〕

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples.

Examples 1 to 3 and Comparative Examples 1 and 2 Five fume tubes having an inner diameter of 1000 mm, an outer diameter of 1120 mm, a length of 1600 mm, a material age of 28 days, and a surface moisture content of 4% by weight were prepared and set on rotatable mounts. I do.

While rotating these fume tubes at 200 rpm,
Separately prepared primers shown in Table 2 were each 100 g
/ m ² was applied, after the primer is gelled, flake lining material by a spray coating machine (Mitsui Toatsu Chemicals Co. Esta flakes 300B), 1200 g / m ² was coated, dried cured.

After curing, using a commercially available pinhole tester (Pinhole Detector manufactured by Sanko Electronics Research Laboratories Co., Ltd.), inspect the pinholes and defective thickness portions of the flaking material,
For the detected defective parts, the flaking layer was corrected.

 Next, a corrosion resistance test was performed as follows.

Both ends of the sample tube are fixed in a semicircular shape with a corrosion-resistant material and sealed, and the shaft is allowed to stand horizontally, with a maximum depth of 50 mm.
After each chemical solution at 60 ° C. is added and kept in an atmosphere at the same temperature for 5 hours, the chemical solution is removed, and the inner surface of the flaking layer and the cross section of the flaking layer + primer layer and the fume tube are visually observed.

Table 1 shows the primer composition and conductivity, and Table 2 shows the characteristics of the primer and the flaking material.

[Effects of the Invention] The primer composition of the present invention (Examples A, B and C) has a conductivity (volume resistivity) of 10 ⁸ Ωcm or less, and can detect a defective portion by a pinhole tester. The primer composition of the products (Comparative Examples D and E) has a conductivity of 10 ⁸ Ωc
It is evident from Tables 1 and 2 that the difference is not less than m and that a defective portion cannot be detected.

Further, it is clear from Table 2 that the composite pipe of the present invention has better corrosion resistance than the conventional pipe.

Claims (1)

(57) [Claims] 1. A corrosion-resistant composite pipe in which a flaking material is lined on the inner surface of a concrete pipe, a fume pipe or an asbestos pipe, wherein an unsaturated polyester resin, an epoxy resin, a vinyl ester is provided between the inner face of the pipe and the flaking material layer. A corrosion-resistant composite pipe comprising a conductive primer layer having a volume resistivity of 10 ⁸ Ωcm or less, wherein the matrix is a resin or a thermosetting resin such as a urethane resin.