JPS6140152A - Heat-shrinkable article - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] - The present invention relates to a heat-transmitting article suitable for corrosion protection of pipelines for transporting fluids such as oil and gas.

[Conventional technology and its parallels]

Pipelines for transporting fluids such as oil and waste are constructed by welding and connecting polyethylene lined steel pipes. Various methods can be used to prevent corrosion of welded joints of steel pipes.
One such method uses a heat-shrinkable tube having a hot-melt adhesive layer provided on the inner peripheral surface of a polyethylene heat-shrinkable base material.

When transporting fluids such as oil and gas, the fluid is heated to approximately 80 to 100°C in order to improve transport efficiency, but in recent years, transportation methods that raise the fluid temperature to approximately 120°C have been introduced to further improve transport efficiency. has been proposed, and a polypropylene-lined steel pipe for pipeline construction that can be used with the scissors method has been developed.

As mentioned above, pipelines made of polypropylene-lined steel pipes are heated up to about 120°C during fluid transport, and the anticorrosive material at the hemorrhoidal joints of the steel pipes also forms a lining layer on the outer surface of the steel pipes. Heat resistance equivalent to or higher than that of polypropylene resin is required, and conventional polyethylene heat-throwing tubes are no longer able to perform this function.

By the way, as a method for manufacturing a heat-shrinkable article provided with a hot melt adhesive layer, a sheet for forming a net melt adhesive layer, such as an ethylene-vinyl acetate copolymer sheet, is completely wrapped around a heat-resistant core, and then a sheet for forming a net melt adhesive layer is further wrapped around the heat-resistant core. A method of obtaining a tube-shaped article by wrapping a heat-shrinkable sheet around the material, then heating it to fuse the two sheets together and forming a tube, and then cooling and removing the core, or hot-melt bonding. A method is known in which a sheet-like article is obtained by overlapping a sheet for forming an agent layer and a heat-shrinkable sheet and applying heat and pressure to fuse the two sheets.

However, when performing the above FA using a polypropylene heat-shrinkable sheet, the heat-shrinkage rate of the resulting heat-shrinkable article is smaller than that of the heat-shrinkable sheet used. .

It is difficult to obtain a practical heat throw rate of 1!1f-j. This is because the heat-shrinkable sheet made of polypropylene reduces or disappears (so-called "heat shrinkage") which is imparted to itself by heating when it is bonded to the sheet for forming the hot-melt adhesive layer. (Forgetting the memory of contraction ") 〇 [A means for the problem TM tips] The present inventions are intentionally considered in the above status, and the polypropyireai layer is the middle layer, and this one side is thermal contract. According to a heat-shrinkable article in which a specific graft copolymer-containing layer is formed on one side of a polypropylene-lined steel pipe on the other side, welding of a polypropylene-lined steel pipe! We have discovered that it is possible to easily form a heat-resistant anti-corrosion coating layer based on a polypropylene resin layer on the ij and liN portions by heat shrinkage, and that it is possible to provide the same adhesive strength to steel pipes at high temperatures, and have developed the present invention. It has been completed.

Namely, 1 the heat-shrinkable article according to the present invention has a layer containing a graft copolymer of a polyolefin polymer and an aliphatic unsaturated carboxylic acid or anhydride thereof on one side of a heat-shrinkable base material via a polypropylene layer. The heat-shrinkable base material in the present invention is made of thermoplastic plastic (excluding polypropylene resin), rubber, or a mixture thereof molded into a tube shape, sheet shape, etc. After that, it is cross-linked if necessary, hot-stretched in a predetermined direction, and then rapidly cooled.Additional additives such as rainbow aging pressure-retarding agents, fillers, colorants, and antistatic agents may be added as desired. A polypropylene resin layer and a graft copolymer-containing layer to be described later are successively formed on one side of this heat-shrinkable base material.

The polypropylene layer softens or melts when the heat-shrinkable article is heated, and behaves to follow the heat-shrinkage of the heat-shrinkable base material. The thickness is usually about 1 to 3 mm. Since this polypropylene layer follows the heat shrinkage of the heat-shrinkable base material, it is preferable to use an uncrosslinked polypropylene layer, but it can also be crosslinked to the extent that the followability is not impaired.

The polypropylene resin used in the present invention may be formed from a block copolymer or a linear random copolymer of ethylene and propylene. In this case, the ethylene content is preferably 30% by weight or less.

In the present invention, a layer containing a kraft copolymer of a polyolefin polymer and an aliphatic unsaturated carbonic acid or anhydride thereof is formed on one side of a heat-shrinkable base material via a polypropylene layer.

9 The graft copolymer-containing layer is polyethylene.

Polyolefin polymers such as polypropylene resin, poly-1-butane, poly-4-methyl-1-pentene, ethylene-propylene copolymer, ethylene-1-butene copolymer, propylene-1-butene copolymer and aliphatic It can be formed by a graft copolymer with unsaturated carboxyl or its anhydride alone or by a mixture of a mineral polyolefin polymer and a wrinkle graft copolymer. When a mixture of a graft copolymer and a polyolefin polymer is used, the content of the graft copolymer in the mixture of these two is 0.
It is preferable to mix it so that it is 5% by weight or more.

The aliphatic unsaturated carboxylic acid or anhydride to be graft copolymerized with the polyolefin polymer is not particularly limited, but from the viewpoint of ease of craft copolymerization, acrylic acid, methacrylic acid, maleic acid, anhydride, etc. Maleic acid, citraconic acid, citraconic anhydride, itaconic acid or itaconic anhydride are preferably used.

The grafting rate of the graft copolymer 11C& may be changed depending on the type of unsaturated carboxylic acid to be graft copolymerized with the polyolefin polymer, but it is usually 0.5% or less. Lll~5
It's %. Note that this craft speed is a value calculated using the following formula (I).

(I) The above-mentioned kraft copolymer-containing layer acts as an adhesive (hot melt adhesive) for adherends such as copper pipes, in addition to heat-shrinking the heat-shrinkable article. However, in order to dissolve the cough-containing layer, two types of wax, such as paraffin wax, micro wax, low-molecular weight polyethylene wax, etc., and aliphatic wax are used. Tackifying resins such as petroleum resins, aromatic petroleum resins, copolymerized resins, coumaron indene resins, aliphatic cyclic saturated petroleum resins, etc. can be blended. 4) Waxes & The tackifying resin is a graft copolymer (if a mixture of graft copolymer M-8 and polyolefin polymer is used, both are used)
Each of them is usually used in a proportion of 100 parts by weight or less per 100 parts by weight.

What is the graft copolymer used in the present invention? Ij
, t is a method of immersing a polyolefin-based polymer in an unsaturated carboxylic acid solution, adding a polymerization initiator and polymerizing it by heating, or irradiating the polyolefin-based polymer with radiation at-m to activate the mosquito polymer, and then It can be obtained by a method such as polymerization with an unsaturated carboxylic acid.

The heat-shrinkable article according to the present invention is produced by sequentially winding a graft copolymer-containing layer-forming sheet, a polypropylene sheet, and a heat-shrinkable sheet around a heat-resistant core, and then fusion-bonding the three by heating with a knife. This can be done by forming a tube, then cooling it and removing the core, or by stacking the above three types of sheets in sequence and heating and pressurizing them to fuse them together, and then releasing the pressure after cooling. The present invention will now be described in detail with reference to the drawings. In FIG. 1, 1 is a tubular heat-shrinkable base material 1, on the inner peripheral surface of which a raft copolymer-containing layer 3 is formed with a polypropylene layer 2t interposed therebetween.

To form an anticorrosive coating layer on the welded joints of polypropylene-lined steel pipes using this tubular heat-shrinkable article, for example, the heat-shrinkable article is inserted over the welded joints of the steel pipes and heated with a gas burner or the like. . Upon heating, the heat-shrinkable base material undergoes heat shrinkage, and the polypropylene layer softens or melts.

Since it follows the heat shrinkage of the heat-shrinkable base material, the heat-throwing article is firmly adhered to the kraft copolymer-containing layer 3 on the welded joint of the copper pipes 4, 4, as shown in FIG. Then, an anticorrosive coating layer mainly composed of the polypropylene layer 2 is formed. 5 is a polypropylene inning layer provided on the outer peripheral surface of the steel pipe 4. In general, the adhesive strength between the polypropylene layer and the heat-shrinkable base material is not very high, and if an equilibrium force is applied after the formation of the anti-corrosion coating, peeling may occur at the interface between the two. Since the polypropylene resin layer is firmly held on the bath welding joint of the steel pipe by the kraft copolymer-containing layer, no problem such as loss of anticorrosion function occurs. Note that in order to increase the adhesive strength between the heat-shrinkable base material and the polypropylene layer, the two may be bonded via an adhesive layer.

〔Effect of the invention〕

The present invention is constructed as described above, and since the heat-shrinkable base material is formed on one side of the polypropylene layer and the graft copolymer-containing layer is formed on the other side, polypropylene is mainly used at the welded joints of copper pipes. An anticorrosive coating layer with excellent heat resistance can be easily formed by heat shrinkage.As also shown in the examples below.

The graft copolymer-containing layer allows the heat-shrinkable article to be firmly adhered to adherends such as sea bream V.

〔Example〕

Hereinafter, the present invention will be explained in more detail with reference to Examples. Na'
&, “Parts” in Examples are “parts by weight”.

Example 1 A graft copolymer layer having a thickness of 0.2 mm was placed on a tubular iron core body with an outer diameter of 150 mm, whose outer circumferential surface was coated with fluororesin T and subjected to mold release treatment, and a sheet for forming a layer was wound in a 3-round shape. do.

This graft copolymer-containing layer forming sheet has a specific gravity of 0.
90. Melt index 4.5. li'/10m1n
5 parts of a graft copolymer of polypropylene resin and maleic anhydride (craft ratio 1%), 95 parts of the above polypropylene, aliphatic fk! Consisting of 20 parts of ll-type saturated petroleum resin (manufactured by Arayo Kagaku Co., Ltd., product name: Flucon, softening point: 125°C) and 5 parts of low molecular weight polyethylene wax (manufactured by Mitsui Petrochemical Co., Ltd., trade name: Hiwax, softening point: 128°C). .

On the above-mentioned graft coelectrical composite V layer forming sheet, a specific gravity of 0
．． A sheet with a thickness of 0.2 cm made of uncrosslinked polypropylene (manufactured by Mitsubishi Yuka Co., Ltd., part name Nobleshi) with a 90% mesh index of 1.0 g/10 m1 was wrapped six times,
Furthermore, a long heat-shrinkable sheet made of cross-linked polyethylene (thickness 0
．． 2wx, 50% of the heat distribution in the longitudinal direction) was wound 6 times so that the longitudinal direction was one inch from the circumferential direction of the core,
Secure the end of the winding with heat-resistant adhesive tape to prevent it from unraveling.

Next, the three types of sheets are heated for 60 minutes in a heating furnace at a temperature of 190°C, and the three types of sheets are heat-sealed and tube-formed. By removing the tape and removing the tape, an uncrosslinked polypropylene layer and a graft copolymer-containing layer were sequentially formed on the inner surface of the heat-shrinkable base material to obtain a tubular heat-shrinkable article with a three-layer structure. . The inner diameter of the article is 150
1JI, wall thickness was 3m, and heat shrinkage rate was 50%.

Example 2 Graft copolymer with specific gravity of 0.9. The same procedure as in Example 1 was carried out except that a graft copolymer of polypropylene resin with a melt index of 4-51710 m1n and acrylic acid (grafting rate: 4%) was used, and a three-layer structure was heated! I
I got tenib.

Example 3 A three-layer structure was obtained by carrying out the same procedure as Example 1 except that the graft copolymer as a component for forming the graft copolymer and the polypropylene O compounding portion were each 50%. A heat-shrinkable tube was obtained.

Example 4 All graft copolymer-containing layers were worked up as in Example 1 except that they consisted of a blend of the graft copolymer 5s used in Example 1 and 95 parts of polypropylene.
A heat-shrinkable tenge having a three-layer structure was obtained.

Example 5 A heat-shrinkable tube with a three-layer structure was obtained in the same manner as in Example 1 except that it was formed using the kraft copolymer c/)+ used in Example 2. .

Example 6 Specific gravity 0.90, melt index 4.577/l
Polypropylene formed from a kraft copolymer of polypropylene and acrylic acid (grafting rate 0.1%) with a thickness of 0 m1.
．． All Example 1 and P! except for using the 2H kraft copolymer-containing layer forming sheet! iJ# to obtain a three-layer heat-shrinkable tube.

Example 7 Specific gravity 0.90. Melt index 4.511/l
Examples with mineral content other than using a sheet for forming a layer containing a kraft copolymer formed from a mixture of 1 part of a graft copolymer (graft ratio 5%) of 0 ml of polypropylene and maleic anhydride and 99 parts of the above polypropylene. A heat-shrinkable tube with a 3Ml structure was obtained by working in the same manner as in 1.

The heat-shrinkable tube obtained in each of the above examples has an outer diameter of 100
Insert the polypropylene lining of A into the welded connection of the pipe (preheated to a temperature of about 150°C) and turn on the gas nozzle ψ-
Heat the tube with a glue to shrink it and bond it over the weld joint. Next, the steel pipe was cut into a width of 25 mm, and then the temperature was 25°C and 120°C, and the tensile speed was 50 w/mi.
The adhesion strength was measured by the 90' peeling method under the conditions of n. The results obtained are shown in Table 1.

For comparison, instead of the kraft copolymer-containing layer-forming sheet, a 0.2-thick hot-melt adhesive layer-forming sheet made of ethylene-vinyl acetate copolymer with a melt index of 59710 ml and a vinyl acetate content of 14% by weight was used. At the same time, data for a heat-shrinkable tape obtained by performing the same procedure as in Example 1 except for using a sheet is shown.

jl! 1 table

[Brief explanation of the drawing]

FIG. 1 is a detailed view showing the performance of the heat-throwing material crystal according to the present invention, and FIG. 2 is a cross-sectional view showing an example of the use of the heat-throwing material. 1... Heat throwable base material 2... Polypropylene resin layer 3
... Graft co-electrical combination tV layer Figure 1 Figure 2

Claims (1)

[Claims] A heat-shrinkable material characterized in that a layer containing a graft copolymer of a polyolefin polymer and an aliphatic unsaturated carboxylic acid or anhydride thereof is formed on one side of a heat-shrinkable base material via a polypropylene layer. Goods.