JPH058300A - Material for joining seal material - Google Patents

Abstract

PURPOSE:To enhance the modulus of elasticity at high temp. and to engage and reinforce the joined part of a seal material by a method wherein a crosslinking promoter is added to and mixed with a polyamide type polymer and the resulting mixture is irradiated with electron beam to obtain crosslinked polyamide used as a substrate. CONSTITUTION:After a crosslinking promoter is added to and mixed with a polyamide type polymer, the resulting mixture is irradiated with electron beam to obtain crosslinked polyamide 2 which is, in turn, integrally bonded to a reinforcing material to form the substrate of a material 1 for joining a seal material. An adhesive 4 consisting of a heat-softenable polymer and a self-adhesive is laminated to the substrate to obtain the desired material 1 for joining the seal material. By this method, the heat resistance and modulus of elasticity of the material for joining the seal material are increased.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sealing material in the form of a tape or a sheet, and more particularly to a sealing material-bonding material based on a crosslinked polyamide used for bonding the ends of a heat-shrinkable sealing material.

[0002]

2. Description of the Related Art A tape or sheet-like sealing material (hereinafter simply referred to as a sealing material) made of a polymer material, particularly a heat-shrinkable polymer material, is used for wires, power cables, water and sewage, city gas, It is used for anti-corrosion coating of pipelines such as crude oil transportation, various pipelines of factory plants, connection parts of various marine structures, and various applications such as coating and sealing of their ends. There is. In particular, for large-diameter pipes such as pipelines, a sheet-shaped heat-shrinkable sealing material is used instead of the heat-shrinkable tube that has been used for covering conventional small-diameter pipes such as cables. These sealing materials are usually adhered and held to each other by an adhesive applied to their ends. However, there are various problems in handling workability of the adhesive, and other materials for bonding the sealing material have been proposed. For example, Japanese Examined Patent Publication No. 61-7937 discloses a method of joining the ends of a heat-shrinkable sheet material, and an adhesive product and an adhesive composition used therefor.

In particular, a heat-shrinkable sealing material shrinks due to heating and comes into close contact with an adherend or the like. The joining material used therefor is mainly joined to the sealing material by heating before the sealing material shrinks. It is necessary to bond the sealing materials to each other and to tightly fix and hold the sealing materials even during the subsequent heat shrinkage. Therefore, various polymers that are stable and do not melt at the shrinking heating temperature of the sealing material are used as the base or a part of the bonding material. In the above publication, polyolefins, polyamides, polyvinyl halides, polyarylketones, polyfluorocarbons, crosslinked polyethylene and the like are mentioned as preferable, but conventionally, heat-shrinkable sealing materials and their bonding materials, Conventionally, most of the polymers used for coating the straight portion other than the connecting portion of the pipe are made of polyethylene.
However, in recent years, there has been a tendency for crude oil or the like to be transported at a high temperature of 90 ° C. or higher in a pipeline, or to be transported at a high pressure in the middle of the pipeline to improve transport efficiency, and polyethylene has a problem in heat resistance. Therefore, polypropylene,
A heat-resistant polymer material such as polyamide has been used for the straight portion of the pipeline. In this case, of course, it is necessary to use a sealing material made of a heat-resistant material such as polyamide also in the connection portion, and development of a bonding material for that purpose is desired.

[0004]

DISCLOSURE OF THE INVENTION The present invention aims to provide a joining material for joining the above-mentioned heat-resistant sealing material, in particular, a heat-resistant and heat-shrinkable sealing material. However, it was completed by discovering that the crosslinked polyamide can be more suitably used as a joining material for heat-resistant sealing materials.

[0005]

According to the present invention, a cross-linking polyamide obtained by irradiating an electron beam after adding and mixing a cross-linking accelerator to a polyamide-based polymer is used as a base material, and a sealing material-bonding material. Will be provided.

Furthermore, there is provided a sealing material joining material comprising an adhesive layer composed of a thermosoftening polymer and a pressure-sensitive adhesive, which is laminated on a substrate formed by integrally bonding the crosslinked polyamide with a reinforcing material. It

[0007]

[Operation] The sealant-bonding material of the present invention is constructed as described above, and the base thereof is a crosslinked polyamide obtained by adding and mixing a crosslinking accelerator to a polyamide polymer and crosslinking by electron beam irradiation. The properties are improved, and the elastic modulus is increased at a temperature near the melting point of the resin or higher, so that various sealing materials such as heat-shrinkable sealing materials can be stably bonded and held.

The present invention will be described in more detail below. The present invention is one in which a polyamide-based polymer is cross-linked and used, but generally, the effect of cross-linking of a polymer material is, in the temperature range near the melting point or higher thereof, tensile strength, modulus, etc. Examples include increasing mechanical properties and preventing thermal deformation such as heat shrinkage and high temperature creep. Further, it is generally known that a polymer material containing a polyamide polymer is difficult to be crosslinked by irradiation with radiation or addition of an organic peroxide. However, it is well known that crosslinking is achieved by adding a crosslinking accelerator such as a polyfunctional monomer having two or more double bonds. The physical properties and the like of these crosslinked polyamide-based polymers were considered, and the application of the heat-resistant seal material as a joining material was made by the inventors for the first time.

The polyamide polymer in the present invention is
Representative examples of so-called nylon include nylon 6 of nylon 6, nylon 9, nylon 11 and nylon 66 of nylon 66, nylon 610. Further, in consideration of flexibility after crosslinking, an elastomer may be added to these polyamide-based polymers if necessary. Examples of the elastomer include synthetic rubbers such as ethylene-propylene rubber and butyl rubber, and ionomers. The amount of the elastomer added is preferably about 5 to 30% by weight based on the polyamide polymer.

Various kinds of cross-linking accelerators have been known so far, but as the cross-linking accelerator added to the above-mentioned polyamide polymer, polybasic acid allyl ester is preferable, and further diallyl maleate, N, N. '-Methylenebisacrylamide, triallyl cyanurate (TAC),
Triallyl isocyanurate (TAIC) and triallyl phosphate (TAP) are particularly preferred. When these polybasic acid allyl esters are added to and mixed with the polyamide-based polymer, and electron beam irradiation is performed without adding them, in order to obtain a gel fraction value indicating the degree of crosslinking of 50% or more, 50 Mrad is required.
While the above dose is required, the polyamide polymer can be highly crosslinked by irradiation with a small dose of electron beam. The addition amount of the crosslinking accelerator is preferably about 2% by weight to 5% by weight with respect to the polyamide polymer. The amount to be added can be appropriately selected within the above range in consideration of the predetermined degree of crosslinking and the amount of electron beam irradiation. If the addition amount of the crosslinking accelerator is less than about 2% by weight, a large dose of electron beam irradiation is required, which is not preferable. Further, when it exceeds 5% by weight, the crosslinking degree does not increase any more even if the irradiation amount of the electron beam is increased.

In the present invention, the dose of electron beam irradiation after addition of the crosslinking accelerator may be extremely small as compared with the case where the crosslinking accelerator is not added as described above, about 3 to 20 Mr.
ad is sufficient. If it is less than about 3 Mrad, a sufficient crosslinking effect cannot be obtained, and even if it is irradiated at more than 20 Mrad, an increase in crosslinking cannot be expected. The crosslinked polyamide obtained by adding a crosslinking accelerator to the above polyamide-based polymer and irradiating it with an electron beam has a reduced elongation, but has a significantly high modulus (elastic modulus) at 100% elongation at high temperature, for example, 230 ° C. improves. Therefore, in the present invention, the bonding material based on the crosslinked polyamide having an increased modulus is elastic against temporary expansion during the bonding of the sealing material or, in the case of the heat shrinkable sealing material, the contraction of the sealing material due to heating. It is preferable that the bonding can be maintained.

The above-mentioned crosslinked polyamide can be used as a joining material for a joining portion of a sealing material by applying an adhesive and a pressure-sensitive adhesive to itself to provide an adhesive layer. Further, it is preferable that the reinforcing member is integrally formed with the reinforcing member as described below and used as the reinforcing member for joining the sealing material. A specific example of the sealing material joining material using the above crosslinked polyamide will be described with reference to the drawings. However, the joining material of the present invention is not limited by these drawings. FIG. 1 is a cross-sectional explanatory view of a sealing material joining panel according to an embodiment of the present invention in which a reinforcing material and an adhesive layer are integrally bonded using a crosslinked polyamide as a base. In FIG. 1, a sealing material joining panel 1 is formed by integrally joining and molding a crosslinked polyamide layer 2, a reinforcing material layer 3 and an adhesive layer 4. As the reinforcing material, inorganic fibers such as glass fibers and mineral fibers, single or mixed fibers such as animal fibers, plant fibers or organic fibers such as plastics, or non-woven fabrics or woven fabrics of these fibers can be used. Lamination of the reinforcing material and the crosslinked polyamide can be performed by heating and / or pressing integrally with the adhesive layer.

For the adhesive layer, it is preferable to use a cross-linked hot-melt type adhesive composed of a mixture of an adhesive thermosoftening polymer and a pressure-sensitive adhesive. As the adhesive thermosoftening polymer, a copolymer of ethylene and a polar monomer of unsaturated ester or acid is used. Examples of the unsaturated ester or acid polar monomer include vinyl acetate, vinyl propionate, vinyl butyrate, butyl isobutyrate, vinyl benzoate, and other vinyl esters, methyl acrylate, ethyl acrylate, methyl methacrylate, and methacrylic acid. Examples thereof include unsaturated acid alkyl esters and aryl esters such as ethyl acidate, n-butyl acrylate, phenyl acrylate, methyl crotonate, and ethyl crotonate, and acrylic acid and methacrylic acid. Preferred are a copolymer of ethylene and vinyl acetate, a copolymer of ethylene and ethyl acetate, and a terpolymer of ethylene, vinyl acetate and acrylic acid or methacrylic acid. As the pressure-sensitive adhesive for the adhesive layer, various types of rubber-based, acrylic-based, vinyl-based pressure-sensitive adhesives can be used.

If necessary, an antioxidant or a crosslinking accelerator is added to the above mixture of the adhesive heat-softening polymer and the pressure-sensitive adhesive,
After irradiation and cross-linking with a dose of 5 to 30 Mrad by electron beam irradiation or the like, it can be laminated with the above-mentioned reinforcing material and applied and laminated on one surface of the integrally reinforced and cross-linked polyamide laminate. The sealant-bonded panel configured by laminating as described above may be separately crosslinked with the polyamide resin and the adhesive layer, or after forming a laminate,
It is also possible to crosslink together by electron beam irradiation or the like.

[0015]

EXAMPLES The present invention will be described in detail below with reference to examples. However, the present invention is not limited to the following examples.

Example 1 Nylon 6 (melt flow rate at 235 ° C. (MF), which is a composition of a polyamide resin conventionally used as a sheet for laminated steel sheets, as a raw material for crosslinked polyamide
R) of 15 to 21 and 235 ° C. melt flow rate (MFR) of 12 to 18), ethylene-propylene manufactured by Japan Synthetic Rubber Co., Ltd. as a modifier for imparting flexibility. A composition comprising rubber and an ionomer and the above-mentioned TAC, TAIC or TAP as a crosslinking accelerator was obtained by kneading at a composition ratio shown in Table 1 using a verander mixer.

Next, each of the obtained kneaded compositions was subjected to a 30 mmφ extrusion molding machine (THERMOPLA) having a preset temperature of 230 ° C.
Melt extruded using STICS), cooled with water, and made into 2 mmφ × 3 mm cylindrical pellets by a pelletizer (Chuo Kikai). After drying each of the obtained pellets, a hot press molding machine (manufactured by Shinto Metal Industry Co., Ltd.) was used to obtain a temperature of 230.
By compression molding at ℃, each sheet-shaped test piece of 180 × 180 × 1.0 mm was produced. Each test piece was irradiated with an electron beam in a room temperature at room temperature using a Van de Graaff electron beam accelerator. The irradiation conditions were 3 passes at a speed of 5 m / min, the current was changed to 10, 20, and 30 mA, and the irradiation dose was set to about 5 Mrad, 10 Mrad, and 15 Mrad, and irradiation was performed, and a crosslinked polyamide test piece was used. Manufactured. For each of the obtained test pieces, the test piece was punched out with a tensile test dumbbell of JIS K7113, and 150
Tensile strength tests at ° C and 230 ° C were measured, respectively.
The results are shown in Table 1.

[0018]

[Table 1]

From the above results, compared with the conventional unirradiated sheet material composition for laminated steel sheet of Sample No. 7, the electron beam-irradiated crosslinked polyamide of the present invention has a decrease in elongation at 150 ° C. At a high temperature of 230 ° C., the elongation and the strength at break are also improved, and particularly the 100% modulus is remarkably improved, and it is found that the material is suitable as a bonding material for various sealing materials, particularly as a bonding material for heat-shrinkable sealing materials. On the other hand, when the conventional sheet material composition for laminated steel sheets of Sample No. 6 is simply irradiated, the test piece becomes brittle and the improvement in elastic modulus is low. This is presumed to have less intermolecular crosslinking.

Example 2 A non-woven fabric having a thickness of 0.1 mm was fitted as a reinforcing material to the surface of the crosslinked polyamide of Sample No. 4 obtained in Example 1 above.
It was heated to 230 ° C. and pressurized to obtain a reinforced crosslinked polyamide piece. An adhesive layer made of a mixture of an ethylene / ethyl acrylate copolymer and coumarone resin was formed on the surface of the obtained non-woven fabric of the reinforced cross-linked polyamide piece to prepare a laminated panel having the structure shown in FIG. FIG. 2 is a perspective explanatory view in which the laminated panel obtained above is applied to a joint portion of a seal material covering a pipe weld joint portion. In FIG. 2, the obtained laminated panel 1 is applied on the adhesive layer side of the laminated panel on the joint end portion 6 of the heat-shrinkable sheet 5 whose main component is polyethylene coated on the welded joint portion 8 of the pipe 7. Pressed and joined.
Then, the heat shrinkable sheet 5 part was heated to 80 to 20 ° C. to shrink. As a result, the heat-shrinkable sheet 5 was fastened and fixed around the pipe 7. On the other hand, also in the laminated panel 1, the heat-shrinkable sheet 5 was fastened and fixed without breaking, and cracks and the like did not occur.

[0021]

INDUSTRIAL APPLICABILITY The crosslinked polyamide of the present invention has improved elastic modulus at high temperature and the like, and engages and reinforces the joint portion of the seal material, particularly the heat-shrinkable seal material, so that the seal material can be tightened without breaking or cracking. It can be attached and fixed and is industrially useful.

[Brief description of drawings]

FIG. 1 is a cross-sectional explanatory view of a sealing material joining panel according to an embodiment of the present invention.

FIG. 2 illustrates a sealing material joining panel according to an embodiment of the present invention,
It is isometric view explanatory drawing applied to joining of the sealing material with which the pipe welding joint part was covered.

[Explanation of symbols]

1 Laminated panel 2 Cross-linked polyamide
3 Reinforcement material 4 Adhesive layer 5 Seal material
6 Seal material joint end 7 Pipe 8 Weld

Claims (1)

Claim: What is claimed is: 1. A cross-linking polyamide obtained by irradiating with an electron beam after adding and mixing a cross-linking accelerator to a polyamide-based polymer as a substrate.