JP2002136920A - Method for coating outer surface of synthetic resin pipe with hot melt adhesive - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for coating the outer surface of a synthetic resin pipe having thermal diameter expanding properties with a hot melt adhesive, not peeling the adhesive when the synthetic resin pipe is inserted in a steel pipe at the time of lining and used in the steel pipe of which the inner surface is lined with a synthetic resin without using a solvent. SOLUTION: The outer surface of the synthetic resin pipe is heated to a temperature range from 60 deg.C to the softening temperature of the synthetic resin +10 deg.C by near infrared rays and the heated outer surface is coated with the hot melt adhesive in such a state that the temperature of the outer surface is 60 deg.C or higher.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for applying a hot-melt adhesive to an outer surface of a synthetic resin pipe, and more particularly, to a method of applying a hot-expandable synthetic resin pipe used for an inner lining steel pipe of a synthetic resin. The present invention relates to a method suitable for applying a hot-melt adhesive.

[0002]

2. Description of the Related Art Conventionally, as a method of applying a hot-melt adhesive to an outer surface of a heat-expandable synthetic resin pipe used for a synthetic resin inner lining steel pipe, a hot-melt adhesive is usually applied by a crosshead die. It has been practiced to heat and extrude and apply it to the outer surface of a heat-expandable synthetic resin tube.

[0003] However, in this method, at the moment when the hot-melt type adhesive comes into contact with the tube surface, the backing agent cools down, and the adhesive strength between the adhesive and the surface of the synthetic resin tube becomes weak. When inserting the so-called adhesive, the adhesive peels off, making it difficult to insert or creating a place without adhesive after insertion, reducing the lining strength or leaving air between the synthetic resin pipe and the steel pipe, so-called There is a problem that floating occurs.

In order to solve this problem, Japanese Patent Publication No.
No. 4784 discloses a method in which a solvent diluent having an adhesive concentration of 10 to 25% by weight is applied to the surface of a heat-expandable synthetic resin tube, dried, and then a hot-melt adhesive is applied. However, in this method, a solvent drying device is required, and if the solvent remains in the adhesive due to insufficient drying or the like, the residual solvent boils due to heating during lining processing,
In addition to the possibility that foam may cause poor adhesion between the steel pipe and the synthetic resin pipe, it is necessary to prevent the work environment from deteriorating due to the use of solvents, and to increase the cost and equipment by installing equipment, etc. There are problems such as restrictions on space.

[0005]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned conventional problems and provides a coating method in which a hot-melt type adhesive is adhered to the outer surface of a synthetic resin pipe. A method of applying a hot-melt type adhesive to the outer surface of a heat-expandable synthetic resin pipe used for a synthetic resin inner lining steel pipe without using a solvent when the synthetic resin pipe is inserted and without using a solvent. It was made for the purpose of providing.

[0006]

According to a first aspect of the present invention, there is provided a method for applying a hot-melt adhesive to an outer surface of a synthetic resin tube, the method comprising: Heating the synthetic resin from 60 ° C. to the softening temperature of the synthetic resin + 10 ° C., and applying a hot-melt adhesive to the outer surface while the temperature of the outer surface is 60 ° C. or higher. Is a method for applying a hot melt adhesive.

The synthetic resin pipe used in the present invention includes:
A tube made of a thermoplastic synthetic resin such as a vinyl chloride resin, polyethylene, or polypropylene is used. In the case of a heat-expandable synthetic resin tube, it is a synthetic resin tube having a property such that its outer diameter expands when heated. It is obtained by cooling and solidifying while reducing the diameter so as to have a smaller outer diameter than during extrusion. As the material, for example, a thermoplastic synthetic resin such as vinyl chloride resin, polyethylene, and polypropylene can be cited, and in particular, a material which has a heat swelling property and is generally used as an inner pipe for a synthetic resin inner lining steel pipe. , A vinyl chloride resin is preferably used.

The hot-melt type adhesive used in the present invention is not particularly limited as long as it bonds the inner surface of the steel pipe to the outer surface of the synthetic resin pipe. Examples of the hot-melt adhesive include a polyolefin-based adhesive and an ethylene-vinyl acetate resin-based adhesive. And synthetic resin-based hot-melt adhesives such as polyamide-based, polyester-based, and rubber-based adhesives, which may be appropriately selected and used depending on the purpose of use of the tube, the material of the tube, the tube diameter, and the like.

In the present invention, when the hot melt adhesive is applied to the outer surface of the synthetic resin tube, the outer surface is heated to secure the adhesion between the hot melt adhesive and the synthetic resin tube. When the entire tube wall of the synthetic resin tube is heated, the tube itself may be distorted.In the case of a heat-expandable synthetic resin tube, the tube may be expanded and cannot be inserted into the steel tube, or the lining strength may be reduced. To happen. Therefore, only the vicinity of the outer surface of the synthetic resin tube is heated, and the tube wall on the inner surface side must not be heated.

[0010] The heating method using near infrared rays is a heating method used for this purpose. Wavelength range from 0.8 μm
A substance irradiated with light of 25 μm (near-infrared ray) is characterized in that only its surface is heated and the deep part is not heated.

As an apparatus for generating such near infrared rays, for example, there is a lamp using a tungsten filament as a light source, for example. Au, Ag, P
A product that has a near-infrared reflecting mirror coated with t, Al, or the like and that can emit near-infrared light in one direction is commercially available, and can be used. Examples of commercially available products include HYP series and HYL series manufactured by Hivec.

The external shape of the near-infrared ray irradiating device includes a rod shape and an annular shape. In any case, the near infrared ray irradiating device is used if it is arranged so as to uniformly irradiate the entire outer surface of the synthetic resin tube. Well, the arrangement method is not particularly limited. Of course,
When hot-melt adhesive is actually applied, the coating operation is usually performed while the synthetic resin tube is moving in the axial direction. Therefore, the near-infrared ray device is provided over the entire length of the synthetic resin tube. The individual irradiating devices do not need to be provided, and the near infrared rays can irradiate the outer surface of the tube uniformly, and the tube is usually moved to that position.

In the present invention, the outer surface of the synthetic resin tube is heated in a range from 60 ° C. to the softening temperature of the synthetic resin + 10 ° C. If the temperature is lower than 60 ° C., the adhesion between the synthetic resin pipe and the hot melt type adhesive is reduced, and the softening temperature of the synthetic resin is increased.
If the temperature exceeds 10 ° C., deformation of the synthetic resin tube occurs.

The temperature is obtained by near-infrared irradiation by changing the output of the near-infrared irradiation device, the distance to the tube to be irradiated, or the moving speed of the tube. These may be determined by appropriately changing them according to the equipment space, the desired production speed, the dimensions of the target pipe, and the like, and are not particularly determined.

In order to prevent the entire tube wall from being heated beyond the softening temperature of the synthetic resin + 10 ° C., the heating of the outer surface of the synthetic resin tube by near-infrared rays is performed by heating the temperature of the heated outer surface to the inner wall of the tube. It is desirable to stop the heat before the entire wall of the tube is heated to a high temperature. That is, when the outer surface of the tube reaches a predetermined temperature, a hot-melt adhesive is applied at a temperature of 60 ° C. or higher. The irradiation time of the near-infrared ray may be a time in which only the temperature of the outer surface of the synthetic resin pipe is within a predetermined temperature range, and the dimensions of the target synthetic resin pipe, the outside air temperature of the work place, the hot melt What is necessary is just to select and determine suitably according to the application speed of a mold adhesive, etc.

The method for applying the hot-melt adhesive to the outer surface of the synthetic resin tube is not particularly limited. For example, as an example, the hot-melt adhesive is applied to the outer surface of the heat-expandable hard PVC pipe shown in FIG. As shown in a conceptual diagram of an apparatus for applying a hot melt type adhesive, a synthetic resin pipe 1 is guided to a crosshead die 4 having an annular discharge port connected to an extruder (not shown). Before the synthetic resin tube 1 reaches the crosshead die 4, the outer surface thereof is heated by the near-infrared irradiating device 3, and when the outer surface reaches a predetermined temperature, the outer surface is passed through the crosshead die 4, whereby the crosshead die 4 is moved. Hot melt adhesive extruded into cylindrical shape from
Is placed on the outer surface of the synthetic resin tube 1 and closely contacted with a packing 5 or a roller, and then cooled by blowing cooling air with a blower 6 or the like, or a winding roller or the like while extruding a hot melt type adhesive in a belt shape. And a method of closely attaching the outer surface of the synthetic resin tube.

Of course, in any of these methods, the near-infrared irradiating device is disposed immediately before the hot melt type adhesive is bonded to the outer surface of the synthetic resin tube, and the temperature of the outer surface of the synthetic resin tube is set to a predetermined temperature. Needless to say, the hot-melt adhesive is brought into contact at a temperature of 60 ° C. or higher.

The heat-expandable synthetic resin pipe obtained by applying the hot-melt type adhesive on the outer surface obtained by the above method is inserted into a steel pipe for lining, expanded by heating and, if necessary, pressurized. The inner diameter of the steel pipe is brought into close contact with the inner wall of the steel pipe to form a synthetic resin inner lining steel pipe.

(Action) In the present invention, the hot melt type adhesive is prepared in such a manner that the outer surface is preliminarily reduced from 60 ° C. to the softening temperature of the synthetic resin + 10 ° C.
Since it is placed on a heated synthetic resin tube below, the adhesiveness between the synthetic resin tube and the hot melt adhesive is good without using a solvent, and the adhesive does not peel off when inserted into a steel pipe. . In addition, the heating method of the outer surface of the synthetic resin tube is heating by near-infrared light, and since the near-infrared light has a short wavelength, only the outer surface of the synthetic resin tube to which it is irradiated can be concentrated and heated, so that the heating efficiency is good. Further, since only the outer surface of the tube is heated, the tube itself is not deformed even if the surface temperature is heated to the melting point of the synthetic resin or higher.

Further, as soon as the outer surface of the synthetic resin tube reaches a predetermined temperature, a hot-melt type adhesive is applied so that the adhesive and the outer surface of the tube are securely adhered to each other.

[0021]

Next, embodiments of the present invention will be described with reference to Examples and Comparative Examples.

Example 1 A heat-expandable hard vinyl chloride pipe (Ethlon pipe VL20A, softening temperature: 80 ° C., manufactured by Sekisui Chemical Co., Ltd.) was exposed to a near-infrared irradiator (HYD-2).
20D, manufactured by Hybeck Co.) to 85 ° C,
As soon as the temperature reached 85 ° C., a hot-melt type adhesive (Esdine # 9185, rubber type, manufactured by Sekisui Chemical Co., Ltd.) was applied to the outer surface of the above-mentioned vinyl chloride pipe with a crosshead die having an annular discharge port, and then sealed. After being heated and brought into close contact with the tube, the tube was cooled to obtain a heat-expandable hard vinyl chloride tube having an outer surface coated with a hot-melt adhesive.

The obtained heat-expandable hard vinyl chloride tube was
At a speed of 0 m / min, it is inserted into a steel pipe of the corresponding inside diameter,
The pipe was heated and expanded by a conventional method to obtain a hard vinyl chloride resin inner lining steel pipe.

(Example 2) A heat-expandable hard vinyl chloride pipe and a hard vinyl chloride coated with a hot melt type adhesive on the outer surface in the same manner as in Example 1 except that the surface heating temperature was 65 ° C. A resin inner lining steel pipe was obtained.

(Embodiment 3) A heat-expandable hard vinyl chloride pipe is an Ethlon pipe VL40A (softening temperature: 80 ° C., manufactured by Sekisui Chemical Co., Ltd.), and the speed at which it is inserted into a steel pipe is 10
A heat-expandable hard vinyl chloride pipe and a hard vinyl chloride resin inner lining steel pipe coated with a hot-melt type adhesive on the outer surface were obtained in the same manner as in Example 1 except that m / min was used.

Example 4 A heat-expandable hard vinyl chloride pipe was connected to an Ethlon pipe HTVL20A (softening temperature: 120 ° C.,
Sekisui Chemical Co., Ltd.), the outer peripheral surface of the pipe was heated to 120 ° C., and the hot melt type adhesive was PES126E (polyester, manufactured by Toagosei Co., Ltd.). A heat-expandable hard vinyl chloride pipe and a hard vinyl chloride resin inner lining steel pipe coated with the agent on the outer surface were obtained.

Comparative Example 1 A heat-expandable rigid vinyl chloride pipe coated with a hot-melt adhesive on the outer surface and a rigid pipe were prepared in the same manner as in Example 1 except that heating was not performed using a near-infrared irradiation device. A vinyl chloride resin inner lining steel pipe was obtained.

(Comparative Example 2) A hot-air drying furnace (gas fan heater, model X-4-T-
C, manufactured by Takeko Seisakusho) in the same manner as in Example 1 to obtain a heat-expandable hard vinyl chloride pipe and a hard vinyl chloride resin inner lining steel pipe coated with a hot-melt adhesive on the outer surface. Was.

Comparative Example 3 An adhesive solution obtained by dissolving a hot-melt type adhesive (Esdine # 9185, rubber, manufactured by Sekisui Chemical Co., Ltd.) in methylene chloride so as to have an adhesive concentration of 10% by weight was heated and expanded. A hard vinyl chloride pipe is applied to the outer surface of an Ethlon pipe VL20A (softening temperature: 80 ° C., manufactured by Sekisui Chemical Co., Ltd.) and dried at 70 ° C. for 1 minute.
A heat-expandable rigid vinyl chloride tube coated with a hot-melt adhesive (Esdine # 9185, rubber, manufactured by Sekisui Chemical Co., Ltd.) and applied to the outer surface in the same manner as in Example 1. And a hard vinyl chloride resin inner lining steel pipe was obtained.

Comparative Example 4 A heat-expandable rigid vinyl chloride pipe coated with a hot-melt type adhesive on the outer surface and a rigid pipe were prepared in the same manner as in Comparative Example 3 except that heating by near-infrared irradiation was not performed. A vinyl chloride resin inner lining steel pipe was obtained.

Observation was made for any trouble when inserting the obtained hot-melt type adhesive into the steel pipe with the heat-expandable hard PVC pipe coated on the outer surface, and the adhesive performance with the steel pipe was obtained. The determination was made based on the adhesive strength of the hard vinyl chloride resin inner lining steel pipe and the presence or absence of floating of the lined vinyl chloride pipe. Table 1 shows the determination results. The determination or measurement method was as follows. (1) Deformation of resin tube: During the execution of Examples and Comparative Examples, changes in the appearance of the heat-expandable hard vinyl chloride tube were visually observed. (2) Peeling of adhesive at the time of insertion into steel pipe (adhesive peeling): A heat-expandable hard vinyl chloride pipe coated with a hot-melt type adhesive on the outer surface is written in a steel pipe adapted to this. After being inserted at the same speed and pulled out at the same speed, the surface was visually observed. (3) State of the PVC pipe on the inner surface of the steel pipe (inner float): The inner surface of the inner pipe of the hard vinyl chloride resin inner lining was visually observed, and the presence or absence of the float of the PVC pipe was observed. (4) Adhesive strength (peeling strength) between hard vinyl chloride pipe and steel pipe: A hard vinyl chloride resin pipe coated with a hot-melt type adhesive is cut out to a width of 10 mm along the pipe axis direction.
In an atmosphere of 23 ° C., a test was performed by attaching a cloth tape (No. 600, manufactured by Sekisui Chemical Co., Ltd.) to a surface coated with the hot melt adhesive by reciprocating a roller having a diameter of 100 mm and weighing 3 kg twice, and reciprocating twice. Using a tensile tester (Autograph, model AG-10TB, manufactured by Shimadzu Corporation), the obtained test piece was subjected to 180 pulling at a pulling speed of 50 mm / min.
A peeling test in the ° C direction was performed.

[0032]

[Table 1]

[0033]

As described above, the method for applying a hot melt adhesive to the outer surface of a synthetic resin tube according to the present invention is as follows.
In particular, when inserting the heat-expandable synthetic resin pipe into the steel pipe at the time of lining, the adhesive does not peel off, and the outer surface of the heat-expandable synthetic resin pipe used for the synthetic resin inner lining steel pipe without using a solvent This is a suitable method for applying a hot-melt adhesive to the surface.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram of an apparatus for applying a hot-melt adhesive to an outer surface of a heat-expandable rigid vinyl chloride pipe.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Heat-expandable rigid vinyl chloride pipe 2 Hot-melt type adhesive 3 Near-infrared irradiation device 4 Crosshead die 5 Packing 6 Blower

Claims (1)

[Claims] 1. An outer surface of a synthetic resin tube is irradiated with near infrared rays at 60 ° C.
A hot-melt adhesive applied to the outer surface of the synthetic resin tube, wherein the hot-melt adhesive is applied to the outer surface while the temperature of the outer surface is 60 ° C. or higher. How to apply mold adhesive.