JPS5959418A - Lining method of metallic pipe - Google Patents

Abstract

PURPOSE:To improve adhesion to a metallic surface by a method wherein an adhesive layer composed of specific polyolefin is provided on the outer peripheral surface of a thermally expansible synthetic resin pipe through an intermediate layer of a specific composition and this layer is inserted into the metallic pipe and heated. CONSTITUTION:A composite to be prepared is composed of 100pts.wt. of unsaturated fatty group carbonic acid or polyolefin copolymerized by anhydride thereof, 5-100pts.wt. of 1 or more types of tackifier selected from terpene phenol resin or a resin group of 10 or more acid numbers and 30-200pts.wt. of polyolefin elastomer. An adhesive layer of polyolefin where unsaturated fatty carbonic acid or its anhydrate is copolymerized through an intermediate layer of said composition is provided on the external peripheral surface of a thermally expansible synthetic resin pipe. The synthetic resin pipe with said adhesive layer is inserted into a metallic pipe. Then, said resin pipe is enlarged in diameter by heating to line the inside of the metallic pipe.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a method for lining metal pipes using a thermally expandable synthetic resin pipe provided with an adhesive layer on the outer circumferential surface via an intermediate layer that has excellent adhesion to the synthetic resin pipe. It is about the method.

In order to impart chemical resistance and corrosion resistance to the inner surface of metal pipes such as steel pipes, we use metal lining laminated pipes made by pre-coating adhesive on the outer circumferential surface of synthetic resin pipes that have the property of expanding when heated. Insert it into a pipe and heat it to expand and
The method of gluing and lining is well known.

However, conventionally, such methods have used solvent-based adhesives as adhesives, which not only require a drying process due to the solvent they contain, but also pose a risk of explosion due to the presence of solvent vapor. In addition, there were other problems such as deteriorating the sanitary environment. Therefore, in recent years, methods have been developed to use hot-melt adhesives that do not require solvents, but many of them have inferior heat resistance and other properties compared to solvent-based adhesives, making it difficult and difficult to put them into practical use. .

In view of the above-mentioned circumstances, the present invention uses a hot-melt adhesive that is free from the dangers of solvent vapor and deterioration of the sanitary environment, and is superior in quality to conventional methods that use solvent-based adhesives. The purpose of the present invention is to provide a method for lining metal tubes that yields synthetic resin-lined metal tubes that are comparable in any way. The synthetic resin tube is inserted into a metal tube through an intermediate layer, and the diameter of the synthetic resin tube is expanded by heating to form a lining.

The heat-expandable synthetic resin pipe used in the present invention is mainly composed of a synthetic resin, such as polyvinyl chloride, and optionally contains a stabilizer,
The mixture was also mixed with paulownia, a lubricant, etc., and extruded to give it thermal expansion properties.

The adhesive layer having a specific composition to be provided on the outer circumferential surface of the thermally expandable synthetic resin pipe via an intermediate layer may be an unsaturated aliphatic carboxylic acid or polyolefin (7'i7) copolymerized with its anhydride. (hereinafter referred to as "acid-containing polyolefin"), or a mixture of two or more thereof as a main component.

Examples of the 4-unsaturated aliphatic carboxylic acids contained in the acid-containing polyolefin include acrylic acid, methacrylic acid, maleic acid, itaconic acid, and ntraconic acid, and examples of the unsaturated aliphatic carboxylic anhydrides include maleic anhydride and anhydride. Itaconic acid, anthraconic anhydride, etc., used singly or in combination, with a content in the range of θ, 07 to 30 weight ratio, preferably θ, 03 to ko θ weight ratio, for copolymerization 1. Polymerize. In addition, polyolefins include d, polyethylene, polypropylene, ethylene-propylene copolymer,
Ethylene-vinyl acetate copolymer, ethylene-ethyl acrylate copolymer, etc. can be used.

For the above acid-containing polyolefins, for the purpose of improving adhesiveness and adjusting melt viscosity, adhesion agents such as rosins, polyterpene resins, and phenol resins, fillers such as calcilyl carbonate l1, and talc, etc. Other additives such as plasticizers and antioxidants are also added.

The adhesive of the present invention has characteristics such as superior adhesive properties at high temperatures and good affinity with scrap metal surfaces as compared to conventional pot-melt adhesives.

As an intermediate layer to be interposed between the adhesive layer and the synthetic resin pipe, one having the following composition has excellent adhesion to synthetic resins, especially hard vinyl chloride resin, and
It was found that there was little decrease in peel adhesion strength at low temperatures.

+a+ Unsaturated aliphatic carboxylic acid or its anhydride was copolymerized. Polyolefin: 100 parts by weight (bl) 7 or more types of tackifier selected from terpene phenol resins or rosins with an acid value of 10 or more S to 700 parts by weight (C1 polyolefin elastomer...30 to 200 parts) In the composition of the above intermediate layer, the polyolefin copolymerized with (ai) unsaturated aliphatic carboxylic acid or its anhydride is used in the adhesive layer. To explain, since it is of the same type as acid-treated polyolefin, it is strongly bonded integrally with the adhesive layer, and its own cohesive force is almost the same as that of the adhesive layer.

However, with just that, it is not effective against hard vinyl chloride resin, etc.
However, it is difficult to obtain a very low adhesion force.

Therefore, by adding (BL chirchen phenol resin or rosins with an acid value of 70 or higher) to the acid-containing polyolefin, it is possible to increase the affinity for synthetic resins such as vinyl chloride resin and improve adhesion. By adding a type of elastomer, the peel adhesive strength at low temperatures is improved without impairing the shear adhesive strength at room temperature, resulting in an intermediate layer that has excellent adhesive strength at room and low temperatures for synthetic resin pipes. It is.

Here, (bl) terpene phenol'M fat is a copolymer of terpenes and phenol, and examples thereof include α-Bi, -phenol copolymer, rosin-modified phenol resin, and the like.

Similarly, the rosins in (b) include gum rosin, wood rosin, tall oil rosin, hydrogenated rosin, disproportionated rosin,
Examples include polymerized rosins, glycerin esters, pentaerythritol esters, etc. of these rosins.

These rosins need to have an acid value of 70 or higher; if the acid value is lower than 10, they have poor compatibility with acid-containing polyolefins, resulting in reduced adhesive strength at high temperatures. The acid value can be as high as natural rosin (acid value 7, θ~7', Y0), which is the highest class among ordinary rosins.

4k, the terpene phenol resin used in the present invention also contains various softening 7. ', n 10 There is a cure, and you can choose it as needed, but
In order to minimize the decrease in adhesive strength at high temperatures, it is desirable to use a material with a ring and ball softening temperature of 70[theta]C or higher.

A mixture of chirchen phenol resin, etc., 6J, a mixture of chirchen phenol resin or rosin (for historical use, the size is a combination of both, 3 to 700 parts per 700 parts of acid-containing polyolefin, etc.) tishikirj,,p.

~100 copies.

If it is less than 5 parts, it will not be possible to obtain the adhesion force with the synthetic resin pipe that is necessary for practical use, and if it exceeds 700 parts, the adhesive force will drop significantly and the adhesion force will be significantly reduced when the adhesive is too high. Is it different from hot melt adhesive? Become something.

The fcI polyolefin elastomer used in the present invention is typically ethylene and α-olefin A'! This is a thermoplastic elastomer obtained by copolymerizing + and thermoplastic f1:, and ethylene-butene/copolymer elastomer, ethylene-propylene copolymer elastomer, ethylene-propylene-diene copolymer elastomer, etc. can be used. M/l,”
-In addition to elastomers containing ethylene and α-olefin copolymers, elastomers containing ethele/vinyl acetate copolymers, etc.
Q”-a”! *, (d) Can be used in combination with other polyolefin elastomers.

The above polyolefin elastomer exhibits good compatibility with the acid-containing polyolefin, which is the 1: agent, and has a remarkable effect on the peel adhesion strength at low temperatures. Acid-containing polyolefin/30 to θO parts. ! 00 parts, preferably 3θ to ISO parts. If it is less than 30 parts, the improvement in peel adhesive strength at low temperatures will be insufficient, and if it exceeds 200 parts, the shear adhesive strength on split stomach crystals will be impaired. In particular, in terms of torsional rigidity, g
Polyolefin elastomers with flexibility of less than 0 kg/crf are suitable.

In addition to the above, other polymers, rubber components, fillers, waxes, colorants, and antioxidants may be added to the intermediate layer of the present invention, if necessary. If talc is sometimes added, each component can be melt-mixed with excellent dispersion.

Next, to explain the embodiment of the method of the present invention, the adhesive layer described in 1- is applied to the outer circumferential surface of a thermally expandable synthetic resin pipe (for example, d, polyvinyl chloride pipe) via the above-mentioned intermediate layer. To provide this, the intermediate layer and adhesive layer are sequentially extruded while a thermally expandable synthetic resin pipe is inserted through a RAD die into an annular cross, or co-extruded at the same time to cover the outer circumferential surface of the pipe. The method of wrapping a film to wrap the adhesive around the tube with the intermediate layer on top is in accordance with the law.

The adhesive layer thus obtained is applied to the outer circumferential surface through the intermediate layer.Thermal expansion tube (1-synthetic resin/77) is inserted into a metal tube, and hot air from a gas burner is blown from the outside of the metal tube. Expansion and adhesion can be achieved by successively heating from one end to the other or from the center to both ends, or by blowing steam into a thermally expandable synthetic resin pipe. In this case, it is desirable that the heating conditions be such that the metal pipe temperature is /10 to 770C.The metal pipes used in the present invention refer to general pipes such as carbon steel pipes for piping, steel pipes, aluminum pipes, etc. Pipes, etc. can also be used.

Furthermore, in the present invention, when the metal tube used is a metal tube made of zinc or galvanized, the adhesion to the metal surface will be further improved if the adhesive layer has the following composition.

(dl polyolefin copolymerized with unsaturated aliphatic carboxylic acid or its anhydride...100 parts by weight (e) f lupene m fat, terpene phenol resin,
Seven or more types of tackifiers selected from rosins... λ ~ 700 parts by weightffl Thiurams, thiazoles, thioate-based vulcanization accelerators, or sulfur-based vulcanization accelerators Additives of 7 or more types...0.7 to 10 parts by weight fdl, tel are explained in the middle layer.
Corresponding to the contents of t and (1)), the tackifier of (el) is preferably 2 to 700 parts by weight based on the acid-containing polyolefin/θθ part of FDL in order to improve adhesive strength.
5 parts by weight are added. If the amount is less than 2 parts by weight, the effect of addition cannot be obtained, and if it exceeds 700 parts by weight, the cohesive force as an adhesive decreases, and in either case, the adhesive strength becomes weak.

Regarding ingredients), in addition to sulfur, thiurams such as tetrametheltheuram disulfide and tetrabutyltheuram disulfide, -mercabutobenzothiazole,
Select from 7 types or λ or more vulcanization accelerators of thiazole type agents such as dibenzothiazole disulfide and dithioic acid ti type agents such as 1E lead/ether dithiocarbamate and zinc dilobinal dithiocarbamate. It can be used as

The amount of this component fl added is 10% of the acid-containing polyolefin.
0.7 to /θ weight part, preferably O
1, 2 to 9 parts by weight. If it is less than 0.1 parts by weight, the adhesive strength to the zinc surface will be low, and if it exceeds 10 parts by weight, there will be many blisters on the adhesive surface.

In addition to the above three components fd), (el, and ge), other tackifiers, rubbers, fillers, pigments, antioxidants, etc. may be added to the adhesive layer, if necessary.

Next, the present invention will be explained in more detail with reference to Examples.

Example / Thermal expandable polyvinyl chloride pipe (Hishipipe S manufactured by Mitsubishi Plastics Co., Ltd.
θA: Outer diameter 30. qmm) into the annular cross through the RAD die, the annular die has an intermediate layer having the composition shown in Table -/;
Ethylene-acrylic acid copolymer (melt index 2
．． 0, acrylic acid content: 15% by weight) was coated as an adhesive layer on the outer circumferential surface of the tube by coextrusion coating on the outer surface of the intermediate layer. The average thickness of the intermediate layer was SOμ, and the average thickness of the adhesive layer was 2Sμ. Insert this 1-coated thermally expandable polyvinyl chloride pipe into a carbon steel pipe for piping (size SOA: inner diameter 32.qmm) that has been subjected to rust removal and rust prevention treatment, and heat the steel pipe surface temperature to an average of /1I07:: with a gas burner. The lining was heated successively from one end to the other so that the Next, the thus obtained lined metal tube was evaluated using the following method, and the results are shown in Table 1.

Length 1000m from any location of the lining metal pipe
A sample of In was cut out and immersed in goC warm water for 1 hour.
A test was repeated for 60 cycles of 2-hour immersion in C water per cycle. This sample "after durability test"
The inner surface of the sample was visually observed to check for peeling of the adhesive, and the appearance was evaluated. Furthermore, we measured the amount (mm) that the polyvinyl pipe had shrunk by 7 mm from the front end of the metal, and then measured the width of 5 pieces at even intervals. 0 scale adhesion strength measurement test, cut out the test piece, J V/ V/ A
- To/／Press-out strength based on Otsu (Japan Water Works Association standards)
The adhesive strength was measured at 0'c. In addition, the punching strength of the lining pipe before the test was similarly measured and used as the initial adhesive strength. Regarding the evaluation of cold resistance, a sample with a length of 230 mm was cut out from the lining pipe and left in an OC atmosphere for more than 10 hours. The falling weight is 3m.
Dropping the sample from a height of

(al ethylene-acrylic acid copolymer (melt index S, S) (bl 7-lupenphenol resin (softening temperature/5o
C) FC+ ethylene-butene-/copolymer (melt index copolymer, θ) As is clear from the results in Table 1, the intermediate layer contains acid-containing polyolefin (al and sample 7g6/) and acid-containing polyolefin (al and Polyolefin elastomer (
Durability test for sample/f63, which is a combination with C1,
There is no need to evaluate cold resistance, and the initial adhesive strength is extremely weak.
During the cooling process after heating the lining, peeling occurred over the entire surface, making it completely impractical. In addition, acid-containing polyolefin (a)
Sample/f62, which is a combination of and terpene phenol resin (BL), has excellent Fi side durability, but it has poor cold resistance and tends to cause cracks in polyvinyl chloride pipes due to low-temperature impact, etc.
Poor practicality. Sample 4q, which is a combination of (al, fbl, and (el) of the present invention, had excellent durability and cold resistance, and was highly practical.

Example λ Thermally expandable polyvinyl chloride pipe (Hishipipe S manufactured by Mitsubishi Plastics Co., Ltd.
θ, outer diameter Sθ, 9 mm) was inserted into the annular cross through the Rad die, and the annular die was inserted into the /l61I shown in Example/.
The same composition as above was used as an intermediate layer, and an adhesive layer of the composition shown in Table 1 was coated on the outer surface of the intermediate layer by coextrusion coating for a distance of K 1 m above the outer peripheral surface of the tube. The average thickness of the intermediate layer is 0μ,
The average thickness of the adhesive layer (CJ, 23μ) was inserted into a galvanized steel pipe (size 5OA, inner diameter: 2.9rrtm), and the surface temperature of the steel pipe was increased using a gas burner. The sea urchin was heated and lined sequentially from one end to the other.The lining metal quality thus obtained was then evaluated in the same manner as in Example 1, and the results are shown in Table 2.

(di ethylene-acrylic acid copolymer (NrutoIntex 2.0) tel Derpenphenol l1llW (softening temperature IB
-/30C) if) sulfur table - As is clear from the results in Table 1, the adhesive layer was made only of acid-containing polyolefin (di) in Trials 14/165 and (,
)' In sample 46 O which is a combination of Ml-containing polyolefin (d) and terpene phenol resin (e),
Although the initial adhesive strength is good, the adhesive strength is lost after the durability test, and peeling occurs between the galvanized steel pipe and the polyvinyl chloride pipe, making it impractical.

Sample A6g, which is a combination of acid-containing polyolefin (FDL and sulfur), and sample A6g, which is a combination of acid-containing polyolefin (I), terpene phenol tel, and sulfur softener (F), also have good durability. In particular, the sample 16g is excellent as there is little difference between the initial adhesive strength and the adhesive strength after one surface test.

Claims (2)

[Claims] (1) An adhesive layer made of polyolefin copolymerized with an unsaturated aliphatic carboxylic acid or its anhydride is provided on the outer peripheral surface of a heat-expandable synthetic resin pipe with an intermediate layer having the composition shown below. A method for lining a metal tube, which comprises inserting the synthetic resin tube into the tube, expanding the diameter of the synthetic resin tube by heating, and lining the tube. (a) Polyolefin copolymerized with unsaturated aliphatic carboxylic acid or its anhydride...700 parts by weight (bl) selected from terpene phenol resins or rosins with an acid value of 10 or more. Tackifier: 9 to 700 parts by weight (C1 polyolefin elastomer: 30 to 200 parts by weight) (2) Claim 1 in which the adhesive layer has the following composition:
The method described in section. (di polyolefin copolymerized with unsaturated aliphatic carboxylic acid or its anhydride...100 parts by weight tel 7 or 2 or more types of tackifier selected from terpene resins, terpene phenol resins, or rosins) Additives: 7 or more additives selected from λ~ioo additives (fl) General rules for vulcanization of thiurams, thiazoles, ditheoate salts, or sulfur. 0./~/θ heavy view part