JPH0427938B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a heat-shrinkable coating material having a specific adhesive layer suitable for coating the outer peripheral surface of various shaped tubes.

Conventionally, in heavy chemical factory plants, piping for urban central heating, or piping around pump stations for crude oil and natural gas transportation pipelines, the shapes of the piping have been elbows, resistors, valves, and T-shaped pipes.
There are a wide variety of shapes, such as shaped pipes and flange parts, but when conventional heat-shrinkable sheathing materials are applied as they are to these irregular-shaped pipes, the heat-shrinkable sheathing materials
In addition to contraction in the circumferential direction of the tube, for example, displacement in the width direction of the coating material, which is perpendicular to the direction of heat contraction (circumferential direction of the tube), is due to dimensional changes during heat contraction. As a result, the coating material may shift and come off or peel off from the surface of the portion of the irregularly shaped pipe that is to be coated.
This resulted in the creation of voids. In particular, if the irregularly shaped pipe to be coated is a retractor type in which the outer circumferential length (or outer diameter) of the pipe gradually decreases in one direction, a heat shrinkable coating with a large heat shrinkage rate is required. When the material is wrapped around the resistor to form a cylindrical body and subjected to heat shrinkage, during the heat shrinkage,
The coating material that adheres to the periphery of the reducer due to heat shrinkage in the circumferential direction also causes a large contraction in the width direction of the coating material, causing it to shift toward the shorter outer circumference of the tube, causing the tube to be coated to deteriorate. It is removed from that part.

As a result of intensive research into solving the problems that the heat-shrinkable (corrosion-proof) coating material had on the aforementioned irregularly shaped pipes, the inventors discovered that the adhesive layer could be used as an adhesive layer even at high temperatures when heat-shrinking. By adopting a heat-adhesive adhesive layer mainly composed of an elastomer material that can maintain a high value of shear strength related to adhesive force, the heat-shrinkable coating material is able to reduce the amount of damage caused by heat shrinkage. He discovered that problems such as misalignment could be solved and completed this invention.

This invention relates to a heat-shrinkable sheathing material for a deformed pipe in which a heat-shrinkable crosslinked plastic layer and a heat-adhesive adhesive are laminated. At high temperatures, the adhesive layer in some areas exhibits the greatest thermal shrinkage force of its covering material, approximately 0.005
Shear strength within the range of ~0.05Kg/ ^cm2 (ASTM D
The present invention relates to a heat-shrinkable coating material characterized in that it is made of an adhesive whose main component is an elastomer material, and which exhibits an adhesive force expressed by 1002).

The heat-shrinkable coating material of the present invention is placed around various irregularly shaped tubes to form a cylindrical shape, and when heat-shrinked, the adhesive layer has high shear strength at the heat-shrinkage temperature of the coating material. As a result, the coating material, which has been heat-shrinked and tightly adhered to the surface of the irregularly shaped tube, is unlikely to shift in the width direction or partially peel off at high temperatures.

Hereinafter, regarding the heat-shrinkable coating material of this invention,
A more detailed explanation will be given with reference to the drawings.

FIG. 1 is a side view and a plan view showing an example of the heat-shrinkable coating material of the present invention.

FIG. 2 is a perspective view showing an example of a situation in which the heat-shrinkable coating material of the present invention is wound around a deformed tube to be coated, and both ends of the tube are joined to form a cylindrical body.

FIG. 3 is a perspective view showing an example of a situation in which a deformed pipe similar to that shown in FIG. 2 is coated using the heat-shrinkable coating material of the present invention.

The heat-shrinkable coating material in this invention is roughly:
For example, as shown in FIG. 1, heat-shrinkable coating materials (sheets or (Tube) 1.

The crosslinked plastic layer may be formed from a conventionally known heat-shrinkable crosslinked plastic film or sheet, or a laminated sheet thereof.

In this invention, the crosslinked plastic film or sheet has a heat shrinkage temperature of about 80 to 200°C,
In particular, the temperature is about 90 to 180℃, and the heat shrinkage rate is about 20 to 80.
%, especially about 30 to 70%, and furthermore, the degree of crosslinking of the polymer forming the film or sheet, expressed as the gel fraction described below, is about 20%.
~90%, particularly 25-80% is preferred.

The above gel fraction is the weight of the sample (crosslinked plastic film or sheet) that is not dissolved in xylene when it is dissolved in xylene under reflux at a temperature of about 130°C for about 10 hours. (Ag) divided by the weight of all samples used (Bg) times 100.

Gel fraction = (A/B) x 100 (%) The crosslinked plastic layer is made of, for example, polyethylene, polypropylene, ethylene-vinyl acetate copolymer, ethylene-propylene copolymer, polyvinyl chloride, polyester, polyamide (nylon-
6. Thermoplastic resin such as nylon-6,6),
After being formed into a film or sheet by extrusion molding, etc., it is irradiated with radiation such as electron beams, sheet and then the film or sheet about 80 ~
It is suitable if it is formed from a crosslinked plastic film or sheet having heat shrinkability obtained by stretching at a high temperature of 200°C and cooling in the stretched state.

In this invention, the adhesive layer is formed in a high temperature region (for example, a high temperature in the range of about 80 to 200°C) where the heat-shrinkable coating material (or heat-shrinkable cross-linked plastic layer) exhibits the greatest heat-shrinkage force. In, about
Within the range of 0.005~0.05Kg/ ^cm2 , preferably 0.007~
Shear strength within the range of 0.04Kg/ ^cm2 (ASTM D
It consists of an adhesive layer mainly composed of an elastomer material that can exhibit an adhesive force expressed as 1002).

As mentioned above, the adhesive layer maintains adhesive strength (shear strength) at high temperatures, and also has a shear strength of approximately 0.8 to 30 kg/kg at room temperature (around 20°C).
cm ² , particularly about 1.0 to 30 Kg/cm ² is appropriate.

The adhesive layer may be made of, for example, polyisobutene rubber (IIR; butyl rubber), ethylene-propylene copolymer rubber (EPR), ethylene-propylene-
Olefin elastomers such as non-conjugated diene copolymer rubber (EPDM), polybutadiene rubber,
Conjugated diene elastomers such as polyisoprene rubber, styrene-butadiene copolymer rubber, acrylonitrile-butadiene copolymer rubber, chloroprene rubber, chlorosulfonated polyethylene rubber, acrylic rubber, epichlorohydrin rubber,
It is preferable to contain an elastomer component such as other non-conjugated diene elastomer such as chlorinated polyethylene rubber or fluorinated rubber in an amount of about 30 to 75% by weight, particularly 35 to 70% by weight.

The elastomer component of the adhesive layer is as follows:
An elastomer component containing the above-mentioned olefin elastomer as a main component or a mixture of an olefin elastomer and other non-conjugated diene elastomer and/or conjugated diene elastomer is optimal.

In addition to the elastomer component, the adhesive layer also contains
Other polymers for modification that are generally contained in adhesives (modifying polymers), tackifiers, corrosion inhibitors,
Furthermore, an inorganic filler or the like may be added.
Examples of the modifying polymer include polyethylene,
Olefin polymers such as ethylene-vinyl acetate copolymer, ethylene-propylene copolymer, acrylate-ethylene copolymer, polypropylene, polybutene, thermoplastic resins such as polyvinyl chloride, polyamide, styrene polymer, etc. Examples of tackifiers include rosin and rosin derivatives, pinene resins, aliphatic hydrocarbon resins (C ₅
Distillates, pentene, isoprene, 1,3-pentadiene, etc. alone or copolymers), aromatic hydrocarbon resins ( _C9 fraction, styrenes, indenes, etc. alone or copolymers), alicyclic carbonization hydrogen resin,
Examples include coumaron resin, coumaron-indene resin, phenolic resin, naphthenic oil, and modified terpene. In addition, as a corrosion inhibitor,
For example, inorganic corrosion inhibitors such as metal chromates, metal phosphates, metal phosphites, metal borates, molybdates, metal nitrites, metal salts of aromatic carboxylic acids, Organic corrosion inhibitors such as aliphatic or aromatic compounds having a group and tannic acid can be mentioned, and further examples of inorganic fillers include talc, charcoal, silica, alumina, mica, and carbon black. can.

In this invention, the adhesive layer includes approximately 30 to 65% by weight of the aforementioned olefin elastomer, approximately 1 to 20% by weight of the modifying polymer, approximately 10 to 30% by weight of the tackifier, and approximately 0 to 65% by weight of the inorganic filler. A composition consisting of a heat-adhesive adhesive composition of 20% by weight has an adhesive strength (shear strength) of approximately 1.0 Kg/cm ² or more at room temperature and an adhesive strength (shear strength) at high temperatures.
Approximately 0.01Kg/cm ² or more at 80℃, approximately 0.01Kg/cm ² at 100℃
It is optimal because it is as high as above and does not drop rapidly as the temperature rises above it.

In the coating material of this invention, if the elastomer component in the adhesive layer becomes too small, the adhesive will shear due to the heat shrinkage temperature of the heat-shrinkable coating material being about 80°C or higher, similar to general hot-melt adhesives. This is not appropriate because the strength becomes extremely low or rapidly decreases, and if the elastomer component is too large, the adhesive force after cooling to room temperature becomes low, which is not appropriate.

The tackifier is used to impart fluidity to the adhesive,
It is blended mainly for the purpose of imparting toughness, and if too little is used, these properties will be lost, which is undesirable.

In the present invention, the heat-shrinkable coating material may be any material as long as the adhesive layer having high shear strength at high temperatures is provided on the entire surface area of one side of the heat-shrinkable cross-linked plastic sheet. If so, some areas of the cross-linked plastic sheet (e.g., for pipes with gradually decreasing outer diameters, the inner surface of the sheathing material that contacts the larger diameter side, for T-shaped pipes, the inner surface of the sheathing material that contacts the neck of the branch pipe) areas such as)
The above-mentioned first adhesive layer having high shear strength at high temperatures is provided, and the other part following this first adhesive layer is provided with a normal hot melt type adhesive layer having high adhesive strength at room temperature. Two adhesive layers may be provided.

As the second adhesive layer, for example, 30 to 80% by weight of a thermoplastic resin such as polyethylene, polypropylene, ethylene-vinyl acetate copolymer, acrylonitrile-ethylene copolymer, polyvinyl chloride, polyester, polyamide, etc. Asphalt (bitiumen) 0~50% by weight, tackifier 10~
A hot melt type adhesive containing 20% by weight and 0 to 20% by weight of an inorganic filler, etc.
It is suitable because it has excellent adhesive strength (shear strength of about 5 to 30 Kg/cm ² ) at room temperature and can flow and cope with small irregularities on the surface to be coated.

As the tackifier, inorganic filler, other additives, etc. in the second adhesive layer, those already mentioned can be used.

In the construction of the heat-shrinkable coating material of the present invention, for example, first, as shown in FIG. A cylindrical covering material (sheet) 1 is wrapped around the covering material (sheet) 1, and the overlapping portions of both ends of the covering material (sheet) 1 are connected with heat seal tape to form a cylindrical shape, and then the cylindrical covering material 1 is Heat it with the flame of a gas burner and heat it to shrink, making it adhere tightly to the surface of the irregularly shaped tube.
This is carried out by further heating and bonding and covering the coating material 1 with a heat-adhesive adhesive layer 3. In this construction, with conventionally known heat-shrinkable coating materials, the coating material would come off from the plastic resin coating layer 5' on the side with the larger outer diameter of the deformed tube during heat shrinkage, whereas this With the heat-shrinkable coating material of the invention, the adhesive layer having high shear strength at high temperatures during heat shrinkage causes the coating material to separate from the plastic resin coating layer 5' on the side with the larger outer diameter of the irregular-shaped tube. has disappeared.

Note that the heat-shrinkable coating material of the present invention does not necessarily have to be a rectangular sheet as shown in FIG. 1, but may have any shape that adapts to the deformed surface of the irregularly shaped pipe, such as trapezoidal, trapezoidal, etc. It may be fan-shaped or other shapes.

Examples and comparative examples are shown below.

In addition, in the examples and comparative examples, the shear strength of the adhesive is
were overlapped by 12 mm, adhesive was interposed between the overlapped portions, heated to a joining temperature of 130°C for approximately 5 minutes, the steel plates were joined, and the steel plates were simultaneously pulled in the direction of both ends using a universal testing machine. ASTM D 1002 Measured according to the measurement method.

Example 1 After kneading an adhesive having the composition shown below using a kneader at a temperature of 150°C for 5 minutes, a roll of 1.5 mm
The thickness of the adhesive sheet was as follows.

Butyl rubber 30% by weight Ethylene-propylene-nonconjugated diene copolymer rubber 25% by weight Polybutene 5% by weight Coumarone-indene resin 20% by weight Talc 10% by weight This adhesive sheet was measured using the shear strength measurement method described above. 0.029Kg/ ^cm2 at 80℃, 105~110
The shear strength is 0.014Kg/ ^cm2 at 110 to 120℃, and even at 110 to 120℃, the shear strength is 0.014Kg/cm2.
At ℃ it was 1.15Kg/cm ² .

This adhesive sheet was bonded to the entire surface of one side of a cross-linked plastic sheet (thickness 1.0 mm, gel fraction 60%, heat shrinkage rate in the length direction 45%, heat shrinkage temperature 105°C), and a heat shrinkable coating was applied. Material (thickness: 2.5mm, width: 1000
mm, length: 2800 mm sheet) was formed.

As shown in Figure 2, the heat-shrinkable covering sheet was coated with a resinous type deformed tube (outside diameter of large diameter part: 32 inches, outside diameter of small diameter part: 24 inches, length;
610mm) and join both ends with heat-sealing tape to form a cylinder.The cylinder-shaped coating material is heated to approximately 105-110℃ with the flame of a gas burner to heat shrink it. The coating material was brought into close contact with the periphery of the irregularly shaped tube, and heating was continued to bond the coating material to the periphery of the irregularly shaped tube with the adhesive layer.

During the coating, the coating material did not cause any large deviations, especially on the larger diameter side of the irregularly shaped tube, and formed a good coating layer.

Comparative Example 1 An adhesive sheet was formed in the same manner as in Example 1, except that the composition of the adhesive was changed as follows.

Ethylene-propylene-nonconjugated diene copolymer
20% by weight ethylene-ethyl acrylate copolymer
25% by weight Coumaron-indene resin 45% by weight Microwax 10% by weight This adhesive sheet was measured using the above-mentioned shear strength measurement method, and the shear strength was 0.124Kg/cm ² at 80℃, 105~
The shear strength was 0.001 Kg/cm ² at 110°C, and the shear strength decreased more rapidly at higher temperatures than 110°C, and was 24.2 Kg/cm ² at 20°C.

Using this adhesive sheet, a heat-shrinkable covering sheet was formed in the same manner as in Example 1, and in the same manner as in Example 1, the periphery of a resinous type irregularly shaped tube was covered.

This coating uses a cylindrical heat-shrinkable coating sheet of approx.
When heated to 90°C or higher, the coating sheet shifted abnormally on the larger diameter side of the irregularly shaped tube, exposing a wide area of the surface of the tube.

Example 2 A first adhesive layer having the same adhesive composition as in Example 1 was provided in a band shape of about 150 mm in width parallel to one edge in the longitudinal direction of the heat-shrinkable covering sheet, and further, The remaining surface of the covering sheet (width: approximately 850 mm strip surface) was heated in the same manner as in Example 1, except that it had a second adhesive layer with the same adhesive composition as in Comparative Example 1. A shrinkable cover sheet was formed.

Using the heat-shrinkable covering sheet,
The adhesive layer was made to overlap the coating layer of the large diameter part of the resin tube.
The periphery of the irregularly shaped tube was coated in the same manner as in Example 1.

In the coating, the coating material did not cause any large displacement, especially on the large diameter side of the irregularly shaped tube, and showed strong adhesive strength at room temperature in the portion where the tube diameter changed, forming a good coating layer.

[Brief explanation of drawings]

FIG. 1 is a side view and a plan view showing an example of the heat-shrinkable coating material of the present invention. FIG. 2 is a perspective view showing an example of a situation in which the heat-shrinkable coating material of the present invention is wound around a deformed tube to be coated, and both ends of the tube are joined to form a cylindrical body.
FIG. 3 is a perspective view showing an example of a situation in which a deformed pipe similar to that shown in FIG. 2 is coated using the heat-shrinkable coating material of the present invention. 1; Heat-shrinkable coating material, 2; Cross-linked plastic layer, 3; Adhesive layer, 4; Deformed tube (resiuser),
5; coating layer; 6; heat seal tape.

Claims (1)

[Scope of Claims] 1. In a heat-shrinkable coating material for a deformed pipe in which a heat-shrinkable cross-linked plastic layer and a heat-adhesive adhesive are laminated, the entire area on one side of the coating material or its covering The adhesive layer in some areas on one side of the material exhibits the greatest thermal shrinkage force of the coating material at high temperatures of approximately 0.005
Shear strength within the range of ~0.05Kg/ ^cm2 (ASTM D
1002) A heat-shrinkable coating material characterized in that it is formed of an adhesive mainly composed of an elastomer material and capable of exhibiting an adhesive force expressed as: 2 The shear strength of the adhesive layer is about 0.007 to
The heat-shrinkable coating material according to claim 1, which is within the range of 0.04 Kg/cm ² . 3. The heat-shrinkable coating material according to claim 1, wherein the elastomer material that is the main component of the adhesive layer is an olefin elastomer.