JPH036930B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a flexible resin composition for treating the inner surface of a corrugated pipe. Metal corrugated pipes have a corrugated surface that gives them flexibility, and are extremely useful, for example, when installing piping into narrow spaces in existing buildings or structures. . However, such corrugated pipes also have drawbacks such as higher fluid frictional resistance inside the pipe than smooth pipes, and the protrusions inside the pipe are susceptible to corrosion damage, so it is important to reduce fluid frictional resistance and improve long-term durability. Therefore, it is desirable to process or treat the inner surface of the tube by some method. Conventional methods for processing or treating the inner surface of corrugated pipes include (a) inserting a smooth tube into the corrugated pipe to create a double pipe, (b) lining the inner surface of the corrugated pipe with a thermally expandable tube. There are methods such as (c) coating the inner surface of the corrugated pipe with liquid synthetic resin, and (d) painting the inner surface of the corrugated pipe with powder resin paint. However, these methods
Disadvantages include (a) significantly deteriorating the flexibility, which is the most important feature of corrugated pipes, (b) increasing costs, and (c) impracticability when the length of corrugated pipes exceeds a certain level. However, since corrugated pipes have at least one type of restriction, they are currently used in an untreated state in many cases in order to make the most of their characteristics as corrugated pipes. The present inventor has conducted various experiments and research in order to obtain a resin composition for lining that does not substantially impair the flexibility, which is the greatest characteristic of corrugated pipes, and has found that such a resin composition is as follows. We found that it should have the following properties. A: Before lining and immediately after lining (1) It has a viscosity (plastic viscosity = 2 x 10 ⁵ cps or less) that makes it easy to mix and prepare the lining resin and to line (coat) the inner surface of the corrugated pipe, and it can also be used during lining work. maintain a suitable viscosity. (2) There should be no skin irritation, toxicity, or irritating odor due to the volatile components of the resin, and there should be no hygienic problems. (3) From the viewpoint of simplifying work and construction equipment, it should be cured at room temperature. (4) It must have thixotropy to prevent the applied material from dripping until the resin hardens after lining with a spherical pig driven by pressurized air. B After the lining resin hardens (1) The lining adheres closely to the inner surface of the corrugated pipe, smoothing the inside of the pipe, greatly reducing fluid friction resistance, and completely covering the inner surface to prevent corrosion from the inner surface. (2) It must have an elongation rate (500% or more) that can be deformed in response to the expansion, contraction and bending of corrugated pipes, and a mechanical strength that does not cause damage to the lining layer due to expansion, contraction and bending. (3) The lining layer has good resistance to pipe fluids such as city gas and tap water, as well as various components that may be contained in these fluids. (4) Young's modulus (50Kg/
^cm2 or less). (5) Annual temperature change in the construction environment (0 to 35℃)
There is little change in mechanical properties, etc., and there is no low-temperature brittleness. As a result of repeated experiments and research on various resins in order to find a lining material that satisfies the above requirements, the inventor found that epoxy resin satisfies the above requirements better than other resins and is less toxic. It was also found that there were few drawbacks such as flammability. However, conventionally known cured epoxy resins do not exhibit elongation corresponding to the expansion/contraction and bending of corrugated pipes.
It was also found that it could not be put to practical use because it easily breaks and does not maintain low Young's modulus and high elongation at low temperatures. Therefore, as a result of further research in search of a resin composition that satisfies the above requirements, the inventor of the present invention discovered that a combination of a specific base resin and curing agent shown below satisfies the purpose, and finally The present invention has now been completed. Each component constituting the resin composition of the present invention will be described in detail below. A Main resin Epoxy resin The epoxy resin used in the present invention in an amount of 95 to 45 parts by weight based on 100 parts by weight of the main resin is liquid at room temperature, and the main resins are as follows. (1) Glycidyl ether-type epoxy resins of bisphenol A such as bisphenol A diglycidyl ether and bisphenol A diβ-methylglycidyl ether (2) Dimer acid diglycidyl ester, polyalkylene glycol glycidyl ester, diglycidyl hexahydrophthalate Glycidyl ester type epoxy resin such as ester (3) Polyalkylene glycol diglycidyl ether type epoxy resin such as polyethylene glycol diglycidyl ether and pentaerythritol diglycidyl ether (4) Linear aliphatic epoxy resin such as epoxidized polybutadiene In the present invention In this case, one kind of these liquid epoxy resins or a mixture of two or more kinds thereof is used as necessary. For example, the above (1) bisphenol A
Glycidyl ether type epoxy resins have particularly excellent shape retention immediately after coating film formation, whereas (2) glycidyl ester type epoxy resins and (3) polyalkylene glycol glycidyl ether type epoxy resins have excellent shape retention properties immediately after coating film formation. Since it has particularly excellent flexibility, the effect can be further improved by appropriately mixing and using these materials. The amount of epoxy resin is 80 parts by weight in 100 parts by weight of the main resin.
More preferably, the amount is 50 parts by weight. Terminal carboxyl-type butadiene-acrylonitrile copolymer The butadiene-acrylonitrile copolymer having a terminal carboxyl group, which is used in the present invention in an amount of 5 to 55 parts by weight, more preferably 20 to 50 parts by weight, in 100 parts by weight of the main ingredient, can be used at room temperature. It is a liquid, has a structure represented by the general formula (1) below, and has a molecular weight of
It has a viscosity of about 490 to 580 cp and a normal temperature viscosity of about 8000 to 14000 cp. [However, x = 1 to 10, y = 1 to 10, z = 1 to 10
It is. ] Copolymer represented by general formula (1) (hereinafter
If the amount of CTBN (referred to as CTBN) is less than 5% of the weight of the main resin, the resin after curing will not exhibit sufficient flexibility, while if it exceeds 55%, curing will be incomplete. Furthermore, CTBN and the above-mentioned epoxy resin are
It may be used in a state where it has been subjected to an esterification reaction in advance. B Curing agent Polybutadiene oligomer The polybutadiene oligomer used in the present invention at a ratio of 0.15 to 0.8 times the equivalent of the main resin has a structure represented by the following general formula (2), has a molecular weight of about 2000 to 3000, and a viscosity at room temperature of 20000.
~24000cp. [However, m=1-4, n=10-20. ] Since the polybutadiene oligomer represented by general formula (2) contains a large amount of rubber component,
It provides the resin composition of the present invention with excellent rubber physical properties and significantly improves the adhesion of the composition. Furthermore, since the polybutadiene oligomer has acrylonitrile introduced into the main chain, it has excellent compatibility with other materials and produces a uniform cured product with excellent durability. The amount of the above polybutadiene oligomer used is
When the amount is less than 0.15 times, the amount of the other amine curing agent described below to be used together increases, and the flexibility of the cured composition decreases, and the adhesive strength also decreases.
On the other hand, if it exceeds 0.8 times, the amount of other amine curing agents listed below will decrease significantly.
The curing reaction becomes extremely slow, resulting in a cured product that contains uncured parts and has poor properties. Amine Hardening Agent In the present invention, a known amine hardening agent is used in combination with the polybutadiene oligomer of general formula (2) above as a hardening agent in an amount corresponding to the remainder of the base equivalent. Among the known amine curing agents, especially those of general formula (3) Polyamines modified with linear aliphatic polyamines such as diethylenetriamine and triethylenetetramine reduce the viscosity of the entire composition, and reduce the viscosity of the entire composition. It is advantageously used for reasons such as greatly improving toughness. Such an amine curing agent may be used in such a proportion that the total amount with the polybutadiene oligomer of the general formula (2) is equal to the equivalent of the main agent, but an excessive amount may be used. C. Optional Additive Components The following known fillers, non-reactive diluents, etc. can be added to the resin composition of the present invention, if necessary, within a range that does not impede the desired physical properties. (1) A filler can be added in order to maintain a predetermined lining film thickness until the resin hardens after lining and to impart thixotropy to the extent that the coating amount does not sag. As the filler, asbestos powder, which exhibits excellent effects when added in small amounts, is particularly preferred, but powdered materials such as alumina, graphite, and silica can also be used. The amount of filler used is based on the total of 100 parts by weight of the main agent and hardening agent.
It is usually preferable to use about 0.3 to 5 parts by weight. (2) A non-reactive diluent can be added to reduce the viscosity of the resin composition and improve the workability of lining. Examples of the non-reactive diluent include terpene alcohol, benzyl alcohol, dibutyl phthalate, dioctyl phthalate, n-butyl glycidyl ether, and methyl alcohol. The amount of non-reactive diluent used is also not particularly limited, but it is usually 3 to 3 parts by weight per 100 parts by weight of the base agent and curing agent.
It is about 30 parts by weight. (3) A curing accelerator can be added to improve workability by rapidly curing the resin composition after lining treatment.
Examples of the curing accelerator include phenols such as 2,4,6-tris(dimethylaminomethyl)phenol. The amount of curing accelerator used is 100 parts by weight of the base resin and curing agent.
Usually, it is preferably about 0.3 to 3 parts by weight. The flexible resin composition for treating the inner surface of a corrugated pipe according to the present invention has all of the above-mentioned properties before and after curing, and is therefore extremely useful. Examples will be shown below to further clarify the features of the present invention. The meanings of the abbreviations used below are as follows. Epoxy resin...Bisphenol A diglycidyl ether type epoxy resin, trademark "AER331",
Manufactured by Asahi Kasei Corporation. Epoxy resin...dimer acid diglycidyl ester type epoxy resin, trademark "Epicote 871",
Manufactured by Yuka Ciel Co., Ltd. Epoxy resin...Fatty acid diglycidyl ester type epoxy resin, trademark "IPU22G", Okamura Oil Co., Ltd.
Manufactured by Co., Ltd. CTBN copolymer: A copolymer represented by the above general formula (1) modified with an epoxy resin, trademark "EXA992", manufactured by Ube Industries, Ltd. Polybutadiene oligomer...Polybutadiene oligomer represented by the above general formula (2), trademark "Hycar ATBN", manufactured by Ube Industries, Ltd. Modified polyamine: A product obtained by modifying the pisspirocyclic diamine represented by the above general formula (3) with a linear aliphatic polyamine such as diethylenetriamine or triethylenetetramine, trademark "LX-2S", manufactured by Yuka Ciel Co., Ltd. . TAP...2,4,6-tris(dimethylaminomethyl)phenol Example 1 A resin composition of the present invention is made from a main agent and a curing agent obtained by mixing each component in the proportions (parts by weight) shown in Table 1 below. (No. 1) was obtained. The Young's modulus and elongation of the resin composition after curing are also shown in Table 1. Table 1 shows that when the proportion of the polybutadiene oligomer represented by the general formula (2) is less than 0.15 times the equivalent weight on the main resin side (No. 2), the curing agent contains the polybutadiene oligomer represented by the general formula (2). If not included (No.
3) and the case where CTBN in the base agent exceeds 55% by weight (No. 4) are shown for comparison.

[Table] The physical properties in Table 1 were measured as follows. Young's modulus...JIS K6301 "Vulcanized rubber physical test method"
According to
A tensile test was performed at 100 mm/min. Elongation...Same as Young's modulus. Example 2 Resin compositions (Nos. 5 to 8) of the present invention were obtained from a main agent and a curing agent obtained by mixing each component in the proportions (parts by weight and equivalent ratio) shown in Table 2 below. The physical properties of each composition (measurement method is the same as in Example 1) are also shown in Table 2. Table 2 shows cases in which the base agent does not contain CTBN (No. 9), cases in which the curing agent does not contain the polybutadiene oligomer represented by general formula (2) (No. 10), and cases in which the curing agent does not contain CTBN (No. 10), and A case (No. 11) in which the polybutadiene oligomer represented by formula (2) has an equivalent weight of less than 0.15 of the base resin side is also shown.

[Table] Experimental Example 1 Resin composition No. 5 of Example 2 was molded into a plate shape, cured, and then punched into JIS No. 2 dumbbell-shaped test pieces. Next, the obtained dumbbell-shaped test piece was (a) heated from room temperature to 80°C over 1 hour, (b) held at 80°C for 2 hours, (c) cooled from 80°C to -5°C over 2 hours, (d)−
It was subjected to a cold/heat cycle test in which each cycle consisted of holding at 5°C for 2 hours and raising the temperature from (e) -5°C to room temperature over 1 hour. After the specified cycle, the dumbbell-shaped test piece was attached to the Instron universal testing machine.
Distance between chucks 40mm, tensile speed 200mm/min, temperature
A tensile test was conducted at 23°C and a temperature of 60%.
The results are shown in FIG. It is clear that the compositions of the present invention exhibit excellent durability and stability even under extremely severe temperature fluctuation conditions. Experimental Example 2 Resin composition No. 5 of Example 2 was evenly applied to the inner surface of a stainless steel corrugated tube with an outer diameter of 16.3 mm, an inner diameter of 13.8 mm, and a pitch of 3.75 mm to form a smooth cylindrical channel with an inner diameter of 13.4 mm. formed. After the resin composition is cured, the corrugated pipe is cut in the axial direction as shown in FIG. 2, and then stretched in the direction of arrow A-B (axial direction) as shown in FIG. 3 to obtain a cured resin product. caused distortion. The amount of strain in the state before tension shown in Figure 3 is assumed to be 0%, and the amount of strain in the state that becomes a straight pipe due to tension is
The same cold/heat cycling test as in Experimental Example 1 was conducted for each sample at each strain amount when the strain was set to 100%. As a result, the amount of distortion is 0%, 25%, 50%, 75% and
In all 100% samples, no abnormality such as resin peeling or cracking was observed even after 80 cycles. Experimental Example 3 (i) A JIS No. 2 dumbbell-shaped test piece similar to Experimental Example 1 was left for 50 days at a humidity of 90% and a temperature of 23°C, and then subjected to a tensile test in the same manner as Experimental Example 1. The Young's modulus had decreased by approximately 55% compared to the initial value. Further, no volume change occurred in the test piece after being left for 50 days. (ii) When a JIS No. 2 dumbbell-shaped test piece similar to Experimental Example 1 was left in an atmosphere with a benzene concentration of 1% for 50 days, the Young's modulus decreased by about 20% and the volume increased by only 1%. Experimental Example 4 (i) A sample with 100% strain obtained in the same manner as Experimental Example 2 was left under the same conditions as in Experimental Example 3 (i), and the adhesion between the resin and stainless steel was observed. , no abnormality was observed. (ii) A sample with 100% strain obtained in the same manner as Experimental Example 2 was left under the same conditions as in Experimental Example 3 (ii), and the adhesion between the resin and stainless steel was observed, but no abnormality was found. It was not recognized at all.

[Brief explanation of drawings]

FIG. 1 is a graph showing the excellent durability of the resin composition of the present invention under thermal cycle conditions. FIG. 3 is a perspective view showing a test sample.

Claims (1)

[Claims] 1 A. Epoxy resin 45 to 95% by weight and general formula (In the above formula, x = 1 to 10, y = 1 to 10, z = 1 to
10) Butadiene acrylonitrile copolymer with a terminal carboxyl group and a molecular weight of 490 to 580
Main agent consisting of 55 to 5% by weight and B. General formula (In the formula, m = 1 to 4, n = 10 to 20) 15 to 80% (based on the equivalent weight on the main resin side) of a polybutadiene oligomer with a molecular weight of 2000 to 3000 and 85 to 20% of an amine curing agent other than the above A flexible resin composition for treating the inner surface of a corrugated pipe, comprising a curing agent of