JPH0193479A - Coating method for permeating sealant - Google Patents

Abstract

PURPOSE:To allow a sealing material to soak into the mortar lining layer easily and uniformly with high stability for a long period of time, by utilizing centrifugal force, when the mortar lining layer of a metal tube is coated with organic impregnating sealant using a solvent as a carrier. CONSTITUTION:A metal tube is lined with mortar on its inner surface and dipped in hot water. Then, the mortar-lined metal tube is uniformly coated with an impregnating sealant including a solvent as a carrier. The tube is allowed to rotated so that the sealant is impregnated into the mortar lining layer utilizing centrifugal force. The rotation period of the tube is preferably 3 to 60 seconds. Further, in addition to the rotation, the sealant is dried by blowing an air lower than 80 deg.C at a rate lower than 5m/sec whereby the sealant layer is much more improved in its peeling resistance.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method of coating a permeable sealant, and more particularly to a method of coating a surface of a metal pipe mortar lining layer with a permeable sealant.

[Conventional technology]

Conventionally, mortar-lined pipes, in which a mortar lining layer is provided on the inner surface of the pipe to prevent corrosion, have been widely used as cast iron pipes for waterworks.

By the way, if this mortar lining layer is left as it is, alkaline components will be eluted into water, so the surface of the mortar lining layer is usually coated with, for example, an acrylic resin emulsion or a vinyl chloride resin.

However, when applying the above-mentioned coating to the mortar lining surface, depending on the quality of the water flowing inside the pipe, for example, acidic water with a pH of 7 or less or highly corrosive water containing a large amount of free carbonate, pinholes etc. of the coating may occur. It penetrates into the mortar lining through the defect, and as a result, the alkali of the cement is eluted from the pinhole, which may deteriorate the mortar lining over a long period of time, thereby relatively reducing the adhesion of the coating material. The coating film sometimes peeled off due to physical changes such as changes in the direction of water flow or changes in flow velocity.

Therefore, a permeable sealing material has been proposed and implemented that does not form a surface coating but instead penetrates and is adsorbed onto the surface of the mortar lining layer and reacts with the cement composition to prevent the formation of a film on the surface. It has reached the point where

[Problems with conventional technology]

However, when coating the mortar lining layer with the above-mentioned permeable sealant, it is relatively difficult to control the depth of penetration depending on the concentration and viscosity of the sealant, and it is difficult to infiltrate the sealant in a uniform layer. There was.

[Problems solved by the invention]

In view of the above-mentioned problems, the present invention, when applying a permeable sealant to the surface of a mortar lining layer, allows the sealant to penetrate in an extremely uniform layer and forms a thin sealing layer on the surface, thereby ensuring a long-term lifespan. This was done with the aim of obtaining a coating method for a permeable sealant that exhibits stability.

[Technology to solve problems]

That is, the method of applying a permeable sealant according to the present invention involves immersing a metal pipe with a mortar lining on the inner surface in heated water, and then uniformly applying an organic permeable sealant using a solvent as a carrier onto the mortar lining surface of the metal pipe. Another method is to immerse a metal tube whose inner surface is lined with mortar in heated water, and then apply a carrier to the mortar-lined surface of the metal tube. The method is characterized in that an organic permeable sealing material is uniformly applied, and the metal tube is rotated and dried by air blowing at a temperature of 80° C. or less and a wind speed of 5+*/sec or less.

[Effect]

Organic permeable sealants using a solvent as a carrier used in this invention can be roughly divided into silicone-based and non-silicone-based sealants. Silicone-based sealants include methyl siliconate (aqueous solution monomer type) and modified alkyl siliconate ( There are silicone types such as siliconate type (water/alcohol solution type), organic solvent monomer type silane compound type, methyl silicone (organic solvent type monomer type), modified alkyl silicone (organic abrasion monomer type), and non-silicone type. Silicone types include bucryl resin type (organic solvent monomer type), urethane compound type (organic solvent oligomer type), and other optional compound types (organic solvent monomer type).

After uniformly applying the organic permeable sealant using the above-mentioned solvent as a carrier to the surface of the mortar lining layer of the metal pipe, the metal pipe is rotated in order to allow the applied sealant to penetrate uniformly into the surface of the mortar lining layer. viscosity of,
Due to volatility etc., the time is between 3 seconds and 60 seconds.

Note that if the rotation time is 0 to 2 seconds, the sealant will not penetrate into the mortar lining layer and will remain on the surface, and if the rotation time is too long, the sealant will flow freely depending on the unevenness of the sealant, the tube temperature, and the solvent composition of the penetrant. This is because it penetrates and it is not possible to form a film on the order of several microns on the surface.

In addition, the reason why the metal tube is immersed in heated water is to control the evaporation of the sealant by the residual heat of the metal tube after heating and prevent excessive penetration of the penetrating material, and the residual heat temperature is 40℃ to 70℃. It is preferable to set it as the range of.

As described above, the permeable sealant can uniformly permeate the mortar lining surface and form an extremely thin film on the surface, but if the next step is further added, the impregnating application of the sealant can be ensured.

That is, after applying the sealant through the above process, hot air is blown onto it to dry it.

The air blow drying performed together with this rotation process works in conjunction with the above-mentioned impregnation process, and is performed to actively form a film on the surface and control the timing of penetration.

The reason why the temperature of the blown air is set to 80° C. or less is to prevent the melting point of the resin used from being exceeded and to avoid thermal changes. Note that, considering the boiling point of the solvent, it is desirable that the temperature of the blown air be 40°C to 80°C.

Also, setting the blowing air velocity to 5 m7sec or less is as follows:
This is to effectively form a thin film on the surface of the sealant, and if it is larger than 5 m1sec, the impregnation of the sealant
This is because during the drying process, the part that will become the film is washed away by air pressure and a smooth and uniform film cannot be formed.

Note that if the spraying speed is too slow, drying will not be done sufficiently, which correlates with the penetration during rotation as mentioned above, but roughly the lower limit is 3.
It is assumed to be approximately m/sec.

〔Example〕

Next, the present invention will be explained in detail.

After immersing a metal pipe with a diameter of 100mmφ with mortar lining on the inner surface in heated water at 90℃, apply an acrylic resin-based permeable sealant to the inner surface of the mortar-lined tube while it is still warmed at 20℃ to 70℃. The tube temperature was set as shown in Table 1, and after air spray coating at a coating layer of 125 g/m'', the tubes were rotated for the time shown in the table and dried.

The evaluation is as shown in the right column of the same table.

Table 1 In the table, in the evaluation, (1) Appearance ○・・・Smooth surface, good condition Δ...Partial unevenness occurs ×: Indicates that the coating film surface is wavy.

+21PH (direct ○...within the standard x...with the exception of the standard, P) (The value is measured by storing the test water on the inner surface of a reiniig pipe with a diameter of 100 mm at the end, and soaking it in water for 24 hours at 20℃. In the subsequent evaluation of water quality changes, a PHHI of 36 or less was considered to be within the standard.

(3) Surface film thickness ○・・・Film thickness 3μ or less Δ・・・3μ～5μ ×...Same 5μ or more Show things.

(4) Overall evaluation ○...Good Δ...Slightly good ×...Indicates defective.

Next, during the tube rotation in the process of the above example, the temperature was 70°C.
When air blow drying was added under the conditions of ℃ and wind speed of 4.5 to 5 s/sec, and the air blowing speed and finish state of the coating film were tested, the results shown in Table 2 were obtained.
It has been found that a range of 4 s/sec to 5 m/sec is preferred.

Table 2 ×...Survival of waves. In addition, after impregnating the penetrating sealant by rotating the pipe, we tested the correlation between the air blowing temperature and the PH value test after sealing construction, and the results were as shown in Figure 1. It has been found that an air temperature range of 40°C to 80°C is preferable.

Next, a freeze-thaw test and a free carbonated water test were conducted on the mortar-lined pipe coated with the permeable sealant obtained according to the present invention. In the freeze-thaw test, there was no peeling of the coating after 20 cycles, and free carbonated water In the test, no blisters occurred even after immersion for one month.

By the way, when we conducted the same test on mortar-lined pipes coated with a penetrating sealant using conventional spray painting at room temperature, we found that the former developed flaking after 10 to 12 cycles, while the latter developed blistering after one week. It was seen.

〔effect〕

As explained above, this invention utilizes centrifugal force when applying a permeable sealant, making it possible to achieve extremely uniform penetration. It is possible to control both the surface film formation and the surface film formation to ideal conditions, and it is possible to apply a permeable sealant with extremely excellent peeling resistance.

[Brief explanation of the drawing]

v'1 Sorry for the inconvenience - Procedural amendment stamp button August 12, 1988 1, Relationship with the teaching case Patent applicant address 2-47 Shikitsu Higashi-chome, Naniwa-ku, Osaka Name (1
05) Kubota Iron Works Co., Ltd. Representative Representative Director and President Shigekazu Mino 4, Agent 662 (1) Column 6 of detailed explanation of the invention in the specification, contents of amendment (1) Page 6, line 1 of the specification ~ Correct the "residual heat of the metal tube after heating" listed in the second line to "preheating". (2) Change the "residual heat temperature" listed in the fourth line to "preheat temperature"
I will correct it. (3) As stated in lines 13 to 14 on page 7 of the specification, “after immersion, while there is residual heat of 20°C to 70°C” is replaced with “dipped,”
Preheat to 20°C to 70°C.'' (4) Delete the statement "By the way, blistering was observed." written in lines 8 to 12 on page 11 of the specification.

Claims (2)

[Claims] (1) After immersing a metal tube with mortar lining on the inner surface in heated water, uniformly applying an organic permeable sealant using a solvent as a carrier to the mortar lining surface of the metal tube, and rotating the metal tube. A method of painting a permeable sealant characterized by: (2) After immersing a metal tube with mortar lining on the inner surface in heated water, uniformly apply an organic permeable sealant containing a solvent as a carrier to the mortar lining surface of the metal tube, and rotate the metal tube. A method for coating a permeable sealant, characterized by performing air spray drying at a temperature of 80° C. or less and a wind speed of 5 m/sec or less.