JPS59120275A - Coating method of inner surface of iron pipe - Google Patents

Abstract

PURPOSE:To increase adhesiveness, while improving durability and the efficiency of corrosion prevention, by interposing an aqueous coating layer containing a cement component between the cement mortar and epoxy resin layers for coating the inner surface of an iron pipe, before said cement is cured. CONSTITUTION:The inner surface of an iron pipe is coated with cement mortar. Then, said mortar layer before being cured is coated with the layer of an aqueous coating composition of 5-1,000 poise in viscosity comprising 100pts.wt. a mixture containing a cement component, etc. and 15-300pts.wt. water. Thereafter, this coating layer and said mortar layer are cured at the same time. An epoxy resin coating composition is then applied onto the layer of said aqueous coating composition and dried. Said mixture comprises 2-40% the solid part of copolymerized emulsion resin of acrylic acid or methacrylic ester, or the like, 1-10% the solid part of bisphenol epoxy emulsion resin, 10-80% a filler, 10- 60% cement, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for coating the inner surface of iron pipes such as cast iron pipes.

Conventionally, iron pipes have been used in a wide range of fields such as sewer pipes, water supply pipes, and gas pipes, and the inner surfaces of these iron layers have been coated with epoxy resin paint or cool epoxy resin paint for the purpose of corrosion prevention17. However, iron pipes, especially cast iron pipes, have a very large number of single holes and have a porous surface, so defects such as pinholes are likely to occur in the film, and the iron pipe may corrode from these areas, or the coating may deteriorate. There were some drawbacks such as peeling. Therefore, recently, the inner surface of the iron pipe is coated with cement mortar in advance, and then the above-mentioned process is applied. The mainstream 2 is a method of coating with an epoxy resin coating composition such as an epoxy resin paint or a tar epoxy resin paint. However, even with this method, resistance to hot water is poor, and the epoxy resin coating layer may peel off due to efflorescence of cement mortar, and when applied to sewer pipes, it may cause damage to industrial wastewater.

Waste liquids such as domestic wastewater are often in the acidic or alkaline range, which causes blisters to occur in the epoxy resin coating layer, resulting in poor durability. Furthermore, since the cement mortar layer has a rough surface, pinholes are likely to occur before coating with the epoxy resin coating composition.
It has to be smoothed by sanding, etc., which complicates the process and creates a poor working environment.
)Ta.

As Senshu said, the conventional method of coating the inner surface of iron pipes has two problems in terms of performance.
``There were various shortcomings in the work.

In view of the above-mentioned prior art, the present invention aims to provide a method for measuring values that has excellent durability, anti-corrosion properties, etc. and provides a good work environment for removing forest cover on the inner surface of iron pipes. It is. □ The purpose of this is (■) the process of covering the inner surface of the iron pipe with 1Φ cement mortar,
(■) Next, on the unhardened cement mortar layer (a
) l) Acrylic acid or meccrylic acid ester copolymerized emulsion resin (ester is an alkyl group having 1 to 8 carbon atoms)' or copolymerized emulsion resin solid content of the acrylic acid or methacrylic acid ester and styrene...・2-40 weight ratio (ii) Bisphenol type epoxy emulsion resin solid content...1-10 weight ratio) Filler...10-80 weight ratio Cement: 10-60 weight iφ () Said line of workers? xy emulsion resin in an amount of 0.8 to 12% polyamide resin or aliphatic polyvalent amine curing agent, and further various additives as necessary from small amounts, and [(i) + (ii))
Mixture 1 in which the heavy dilution ratio of v) is in the range of (0,15 to 1)
00 parts by weight and (b) a step of coating an aqueous coating composition with a viscosity of 5 to 1000 poise consisting of 15 to 300 parts by weight of water, and simultaneously curing and curing the cement mortar layer and the aqueous coating composition layer, and (2) This is achieved by a method for coating the inner surface of an iron pipe, which comprises the steps of: next applying an epoxy resin coating composition onto the aqueous coating composition layer and drying it.

In the coating method of the present invention, an aqueous coating layer containing a cement component and an epoxy resin component is interposed between a conventional cement mortar layer and an epoxy resin coating layer, which improves the adhesion between both layers. , resulting in long-term durability,
A coating with excellent corrosion resistance etc. can be obtained, and it is possible to obtain a coating with no coating defects as described above. In addition, since the cement mortar layer is coated with the aqueous coating composition while it is still uncured,
Conventional polishing/processes such as sanding are not required □, creating a good working environment.

C1-8 alkyl ester monomer of acrylic acid and C1-8 alkyl ester of methacrylic acid, which are components of the acrylic acid or methacrylic ester copolymer emulsion resin used in the aqueous coating composition of the present invention. Typical monomer alkyl esters include methyl, ethyl, n-butyl, isobutyl, tert-butyl, 2-ethylhexyl, benzyl, fOpyr, isozorovir, 1lec-butyl, and the like. Esters having 9 or more carbon atoms are unsuitable for the synthesis of emulsion resins for cement admixture because they generate glue during emulsion polymerization and the emulsion particles become highly hydrophobic. Also used are copolymer emulsion resins of these acrylic acid (or methacrylic acid) esters and styrene.

Particularly preferred acrylic acid or ethyl methacrylate are methyl methacrylate, ethyl acrylate, butyl acrylate, and 2-1 methyl acrylate. If necessary, a functional group monomer such as acrylic acid, methacrylic acid, 2-hydroquinethyl methacrylate or acrylonitrile is required.

It is also possible to copolymerize monomers such as vinyl acetate in several weight ratios. Tertiary acrylic acid (or methacrylic acid) ester copolymer emulsion)
Or methacrylic acid) ester copolymerized with 2-styrene Gomarkyon resin is mixed with cement, so it is good to have alkaline properties and to have excellent stability when mixed with cement. Alkyl phenol polyethylene top = thyl, 7 formula] Gin ethylene alkyl ether, polyoxyethylene argyl allyl nial, +12' J r tylene glycol A
Ethers such as ester, sorbitan, argyl, sorbitan, sorbitan, sorbitan fatty acid ester, polyglycol fatty acid ester; polypropylene glycol, polyethylene glycol, rv i
3
1 Active agent Peng Deku Nu has a large amount of nonionic layer surfactant even when used in combination with anionic surfactant J-. (The molecular weight of the acrylic emulsion resin is 50,000 to 300,000, preferably 10 to 300,000.
200,000 is 0 profit. Mana minimum film forming temperature is 5
C
Cracks and cracks become easier to crack. Also, the viscosity of the acrylic emulsion resin when the solid content is 40% is 100c.
ps or less is preferable. If it becomes more than that, it is necessary to increase the I of water to lower the viscosity by 1 mil, which lowers the solids content and causes cracking and cracking due to fading during drying of the film.8.
It gets cheaper.

These acrylic emulsion resins are the above mixture (a)
The solid content is blended in the ratio of 2.-40% by weight. If the amount of resin is less than 2 mm, the initial hardness of the coating will decrease and efflorescence will be more likely to occur. On the other hand, resin is 40
If it exceeds the weight limit, Atsuto painting will not be possible and cracks and cracks will easily occur.

In addition, the bisphenol type used for the aqueous breakage II order's proboscis.し、）Yon ill )j as (
It is made by using an emulsifier to make a water-dispersed type of regular fat with a molecular density of 350 to 1,000. , as the resin solid content, the above mixture (,
) middle school 1. 1 to 10 @ bettor is used. 1 layer of clear resin and 6 layers (if there are 2 flashes, 1 layer of cement mortar and Z)
Adhesion deteriorates, drying is delayed, and the pot life is shortened.

In addition, the pigments used in the water composition are extender pigments and inorganic pigments such as calcium carbonate, barium l+n'-acid, magnesyl carbonate, talc, clay, etc.
The filler is used to improve brittleness, increase the amount, and while the composition still maintains flowability and uI properties after application. It is blended to make the resin component float on the coating surface due to the difference in specific gravity, and the particle size (d) is arbitrarily determined depending on the inner surface of the iron layer, but is usually 50 to 1000 μm.
+ Q filler is 10 to 8 in the above mixture (a)
It is blended in a proportion of 0 weight factor. This is because within this range, even thick films can be obtained without cracking, cracking, or cracking.

Also, in aqueous coating compositions, cement, I
- [Examples include Portland cement, blast furnace cement, silica cement, Clafa, Nyusesont, etc.) Cement is 1 in ζli7 in the above mixture (,)
It is mixed at a ratio of 0-60 FA. 10 cement
If the thickness is lower than the weight ratio, the film will crack, cracks will be more likely to occur, and adhesion will decrease. On the other hand, if the weight exceeds 6 (), the film becomes brittle and efflorescence is likely to occur.

Evoquin tfjt fat hardening agent used in the aqueous liquid composition is preferably Noamine or Normint<, 4
7” obtained by small condensation of a dibasic acid or a -1 basic acid derivative, etc. Suitable are aliphatic polyvalent amines such as arylamide resin, ezalenoamine, dicodylene triamine, triethylene-triamine, or aliphatic polyvalent amines modified with phenol resins, epoxy resins, and the like. The amount of curing agent used is 0% of the epoxy resin's epoxy group.
．． It is necessary to use it in an amount of 8 to 1.2 equivalents. 08
If the amount is less than equivalent or exceeds 12 equivalents, the original properties of the epoxy resin, such as adhesion and flexibility, will be significantly lowered, and other performances such as durability will also be lowered, which is not preferable.

Additives that may be used as necessary in the aqueous coating composition include, for example, dispersants, antifoaming agents, thickeners, preservatives, and anti-mold agents to improve coating workability and storage stability. Examples include a water reducing agent, an anti-freezing agent, a film-forming aid for improving film-forming properties, and other anti-rust pigments.

Furthermore, in the mixture (a), (1) acrylic acid (or
(methacrylic acid) ester copolymer emulsion resin or copolymer emulsion resin of acrylic acid (or methacrylic acid) ester and styrene, the sum of the solid content of (ii) the solid content of the epoxy emulsion resin, and the weight ratio of 4v) cement. is [(i)+(ii))10-0915~1. If this ratio is less than 0.15, effrence will occur due to the initial hardness of the coating, and it will not be possible to form a thick film with good coating performance.On the other hand, if this ratio is greater than 1, When the film is thick, cracks and cracks are more likely to occur.

The aqueous coating composition of the present invention comprises the above mixture <a)],
15 to 300 parts by weight of water are blended to parts by weight of O,.

This is because within this range, cement hardening and painting workability are good. If the amount of water is less than 15 parts by weight, the acryl emulsion will tend to aggregate when mixed with cement, while if it exceeds 300 parts by weight, the solid content will decrease and the emulsion will become dull during drying, causing cracks and cracks.

As for the cement mortar and epoxy resin coating composition used in the present invention, those conventionally used can be used as they are. That is, the cement mortar is made of cement such as Portland cement, blast furnace cement, silica cement, fly ash cement, etc., and aggregates with a particle size of 50 to 1000μ such as silica sand, talc, clay, sulfuric acid (Zlium, carbonate magne, ram, etc.). A mixture prepared by adding an appropriate amount of water to a mixture with a weight mixing ratio (1:1.5 to 30) can be typically used.As for the epoxy resin coating composition, bisphenol type epoxy resin, polyamide resin, etc. , curing agents such as aliphatic polyvalent amines, extender pigments such as Merck, clay, and barium sulfate, organic solvents, coloring pigments as necessary, and various additives. A typical tar-edoxy resin paint can be used.

Next, the coating method will be explained.

Before coating the inner surface of the iron pipe, the inner surface is polished with a sand grinder or the like to remove black rust lumps, etc. Then cover with cement mortar. There are no particular restrictions on the coating method, and conventional methods can be applied, but in general, cement mortar is poured into the iron pipe while slowly rotating it, and then the iron pipe is heated at 400 to 450 R.
A centrifugal coating method in which the coating is rotated at high speeds such as P and M is suitable. The thickness of the cement mortar layer can be arbitrarily determined depending on the inner diameter of the iron pipe and its intended use, but 2 to 12 mm is usually appropriate.

After coating with cement mortar, uncured water-based coating composition No. 111 is applied again. The aqueous coating composition can be coated immediately after coating the cement mortar, but may be coated after being left for 20 minutes to 3 hours. Although there are no particular restrictions on the coating method, a suitable method is to coat the iron pipe with a moving air spray or an air spray while slowly rotating the pipe. The thickness of the aqueous coating composition layer can be arbitrarily determined depending on the use of the iron pipe, etc., but it is usually 0.1
~1.5 columns is appropriate.

After coating with the aqueous coating composition, the cement mortar layer and the aqueous coating composition layer are simultaneously cured and hardened. The most suitable curing method is steam curing at a temperature of 35 to 75° C. for 3 hours or more, but the method is not limited thereto.

After the cement mortar layer and the aqueous coating composition layer are cured and cured, they are preferably left to stand for at least 2 hours, and then coated with a poxy resin coating composition. There are no particular restrictions on the method of coating, but the same method as for the aqueous coating composition described above is suitable. After coating, it is dried by a natural drying method in which it is left in the air for about one week.

In some cases, the iron pipe may be forcibly heated to 40 to 80°C before or after being coated with the epoxy resin coating composition. The thickness of the epoxy resin coating composition layer can be arbitrarily determined depending on the use of the iron pipe, etc., but it is usually 0.2 to 1.
An appropriate amount is between 1 and 2.

By the coating method of the present invention as described above, it is possible to obtain a coating that is free from film defects such as blisters, has excellent durability, and has excellent corrosion resistance.

The present invention will be explained below with reference to Examples. In addition, in the example “
Parts are based on weight.

<Cement mortar composition m><Aqueous coating composition><Epoxy resin coating composition> (parts) Examples 1 to 6 and Comparative Examples 1 to 5 The inner surface of a shot-blasted cast iron pipe with an inner diameter of 1200 m+n was coated with the materials shown in Table 1. The cement mortar composition was coated using a centrifugal coating method (dry film thickness: approximately 10 m + n), and the lid was left at room temperature for 30 minutes.Then, the aqueous coating composition shown in Table 1 was coated with a dry film by fully mobile airless spraying. Approximately 800
After coating it so that it has a thickness of μ and leaving it at room temperature for 2 hours, steam curing (
45°C for 3 hours). Then leave it for 2 hours, 81!1
The epoxy resin coating composition shown in the table was coated with a mobile airless sprayer to a dry film thickness of approximately 400 μm and left at room temperature for one week.

Water resistance, hot water resistance, acid resistance, alkali resistance of the obtained film and coating workability of the aqueous coating composition, □f
Udolife's various tests were conducted and the results are shown in the lower part of the table. As is clear from Table 1, the coating formed by the coating method of the present invention had excellent performance.

- Comparative Example 2 with excess cement as water-based coating composition, Comparative Example 3 without epoxy emulsion resin, Comparative Example 4 with no water-based coating composition layer, Comparative Example 5; In addition, Comparative Example 1, which contained acrylic emulsion noyon fat control as an aqueous wave composition and summer composition, had poor painting workability and a short pot life, making it impractical.

Note 1] Test method: Evaluated by immersion in tap water for 1 year 20 No abnormalities △ Some blisters x blister dog Note 2) Test) Evening method: Evaluation immersed in 60℃ hot water for 1 month 20 No abnormalities at all △ Some blister x blister dog Note 3) Test 1 method: Immersion in 5% sulfuric acid aqueous solution for 1 month Evaluation: ○ No abnormality at all △ Some blister x Large blister note 4) Test method: 5 Coercive force Soaked in soda aqueous solution for 1 month Evaluation: ○No abnormalities △Some blisters × Blisters 5) Test method: During airless coating of aqueous coating composition.
/ turn l] Stability 1'F value: ○ Good △ Slightly poor × Poor quality 6] Rating
Value=02 hours or more △1-2 hours x less than 1 hour

Claims (1)

[Claims] (IHI) A step of coating the inner surface of the iron pipe with cement mortar, (1) Then, on the uncured cement mortar layer (,
) (i) Copolymerization of acrylic acid or methacrylic acid ester with Suzalene 7-alcoholic acid or methacrylate emulsion resin (ester is an alkyl bracket with a prime number of υJ of 1 to 8) Emulsion resin solid content: 2 to 40 layers (11)
Bisphenol heli Epogin Emaruno 1 resin solid content
...1~1oΦ-ψ (iii) Filler
...10-80 heavy throat dV) Seven Me
Point... 1 () ~ 6
0 -tit %) 壬M nil^i coepokishemal 7'yonl! It consists of a polyamide resin or an aliphatic polyvalent amine curing agent of 8 to 12 parts of fat (), and a small amount of additives of each part according to necessity, and c (*
)+ (li) ) The small UY ratio of i<) is (0,],
The mixture 1001i'i, -1j ranging from 5 to l)
j part and (b) a step of coating an aqueous coating composition with a viscosity of 5 to 1000 and r=Is consisting of 15 to 30 Φ parts of water, and simultaneously curing and curing the cement mortar layer and the aqueous coating composition layer; and 011) The aqueous coating composition layer is then coated with +9
A method for coating the inner surface of an iron pipe, which consists of clove culm, which is coated with a ginseng resin-based coating composition and dried.