JPH08259704A - Crosslinked tube and heat-shrinkable tube - Google Patents

Abstract

PURPOSE: To obtain a crosslinked tube and a heat-shrinkable tube which are colorless, have excellent transparency, change little in internal diameter with time, and consist mainly of an ionomer resin. CONSTITUTION: This tubes comprise a resin composition consisting of an ionomer resin containing 2-20wt.% plasticizer, the ionomer resin being produced by intermolecularly crosslinking an ethylene/(meth)acrylic acid copolymer with metal ions.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION An object of the present invention is to provide a crosslinked tube and a heat shrinkable tube which are colorless and excellent in transparency. A further object of the present invention is to provide a colorless heat-shrinkable tube having an adhesive layer or a pressure-sensitive adhesive layer on the inner surface and excellent in transparency.

[0002]

2. Description of the Related Art Conventionally, the problems to be solved by the invention
Cross-linked tubes and heat-shrinkable tubes are widely used for insulation of electric wires and cables, protection of terminals and connections from external damage, protection of connections of steel pipes and various pipes, waterproofing, and corrosion prevention. Among these, for applications requiring waterproofing and corrosion protection, a heat-shrinkable tube having a structure in which a pressure-sensitive adhesive layer, more preferably an adhesive layer is provided on the inner surface of the heat-shrinkable tube is used. FIG. 1 is a cross-sectional view of an example of such a heat-shrinkable tube, 1 is a heat-shrinkable tube layer, and 2 is an adhesive layer.

Depending on the application, it may be required that the inside can be visually confirmed after coating the crosslinked tube or the heat shrinkable tube. In such application, transparent polyvinyl chloride or polyethylene terephthalate resin, A crosslinked tube made of an ionomer resin or the like and a heat shrinkable tube are used.

However, in recent years, a heat-shrinkable tube made of a raw material containing no halogen element has been demanded from the viewpoint of environmental problems such that hydrogen chloride is generated when polyvinyl chloride is incinerated. Further, the heat-shrinkable tube using the polyethylene terephthalate resin has a problem that the heat-shrinkable tube greatly shrinks not only in the radial direction but also in the longitudinal direction during the heat-shrinking operation.
Further, a tube made of polyethylene terephthalate resin has a problem that flexibility is insufficient and a thick tube cannot be handled.

Cross-linked tubes and heat-shrinkable tubes using ionomer resins are known to be copolymers of ethylene and acrylic acid or methacrylic acid and having a structure in which the molecules are cross-linked with metal ions such as zinc ions and sodium ions. ing.

As a method for producing a crosslinked tube made of an ionomer resin, a hot melt extruder or the like is used to mold the ionomer resin into a tube shape, and then crosslinked by irradiation with ionizing radiation such as an electron beam, Obtain a crosslinked tube. Further, as a method for producing a heat-shrinkable tube made of an ionomer resin, the ionomer resin is molded into a tube shape using a hot melt extruder or the like, and then crosslinked by a method of irradiating ionizing radiation such as an electron beam, and after crosslinking. Generally, a method of expanding the diameter and cooling and fixing it by a method of sending compressed air into the tubular molded product under heating conditions is common.

A heat-shrinkable tube made of an ionomer resin having an adhesive layer on its inner surface is manufactured by melt-extruding an adhesive resin molded product such as polyamide and an ionomer resin molded product to produce a heat-shrinkable tube of a single ionomer resin. It can be obtained in the same manner as in the case.

The crosslinked tube and the heat-shrinkable tube made of a resin composition mainly composed of an ionomer resin are excellent in transparency and do not generate a toxic gas at the time of combustion because they do not contain halogen, and the heat-shrinkable tube made of polyethylene terephthalate. There is an advantage that there is no problem such as poor handling due to the contraction in the longitudinal direction and lack of flexibility like a tube.

However, in the case of producing a crosslinked tube of an ionomer resin, a heat-shrinkable tube, and a heat-shrinkable tube of an ionomer resin having a structure having an adhesive layer on the inner surface, after extruding the tube and after expanding and expanding the diameter, room temperature is used. Even in the vicinity, the inner diameter shrinks with time over several days to several weeks, and it is difficult to improve the dimensional accuracy of the tube.

Further, by annealing the tube at 50 to 60 ° C. after extrusion, it is possible to reduce the change in the inner diameter of the tube to about several days. In addition, since the heat-shrinkable tube after expansion and expansion starts heat shrinkage by annealing at 50 to 60 ° C., the annealing treatment cannot be performed.

[0011]

Means for Solving the Problems As a result of diligent studies on the above problems, the present inventor has found that even a heat-shrinkable tube having a structure having an ionomer resin-based crosslinked tube, a heat-shrinkable tube, and an adhesive layer on the inner surface The resin composition constituting the crosslinked tube and the heat-shrinkable tube is a copolymer of ethylene and acrylic acid or methacrylic acid, and a plasticizer is added to an ionomer resin having a structure in which intermolecular crosslinking is carried out with a metal ion, from 2 to 20. By using a resin composition containing 1% by weight, the resin composition is extruded at 30 ° C.
It was found that when left for a day, the shrinkage of the inner diameter stopped, and thereafter the dimension did not change with time and became stable, and the present invention was completed based on such findings.

That is, a feature of the present invention is (1) a crosslinked tube and a heat-shrinkable tube made of a resin composition containing an ionomer resin as a main component, wherein the ionomer resin is a copolymer of ethylene and acrylic acid or methacrylic acid. An ionomer resin having a structure in which intermolecular molecules are cross-linked with a metal ion, which is composed of a resin composition containing 2 to 20% by weight of a plasticizer in the ionomer resin. (2) Adhesive layer or adhesive on the inner surface Heat-shrinkable tube on which the agent layer is formed,
It is in.

[0013]

In the ionomer resin of the present invention, zinc ions, sodium ions and potassium ions are particularly preferable as the metal ions for crosslinking the molecules, but the metal ions are not limited thereto.

Examples of the plasticizer include phthalic acid ester, adipic acid ester, azelaic acid ester, orthophosphoric acid ester, sebacic acid ester, trimellitic acid ester, pyromellitic acid ester, paraffin oil,
Examples include aromatic oils and naphthenic oils. A reactive plasticizer is particularly preferable in view of migration of the plasticizer, bloom, and the like, and is selected from bifunctional or trifunctional plasticizers.

As the bifunctional or trifunctional plasticizer, acrylate, cyanurate, isocyanurate or the like can be used. Specifically, trimethylolpropane trimethacrylate, 1,6-hexanediol dimethacrylate, neopentyl glycol can be used. Methacrylate, trimethylolpropane acrylate, 1,6-hexanediol diacrylate, neopentyl glycol diacrylate, triallyl cyanurate, triallyl isocyanurate and the like can be mentioned, and these may be used alone or in combination of two or more. Good.

If the amount of the plasticizer added is less than 2% by weight with respect to the ionomer resin, the effect of suppressing shrinkage is not exerted, and if it exceeds 20% by weight, the inner diameter contraction after expansion and expansion becomes very large, and The agent blooms so much that it is virtually unusable.

The adhesive resin composition used in the adhesive layer of the heat-shrinkable tube of the present invention includes thermoplastic polyamine resins produced by polycondensation reaction of polymerized fatty acid with polyethylene polyamine and various diamines. Thermoplastic saturated copolymerized polyester resin, a resin composition mainly composed of ethylene ethyl acrylate carbon monoxide copolymer, can be preferably used from the viewpoint of adhesion to metals and various substances, but the water absorption of the adhesive resin And transparency,
From the viewpoint of colorability, a resin composition mainly composed of an ethylene ethyl acrylate carbon monoxide copolymer can be particularly preferably used.

If desired, various additives such as antioxidants, light stabilizers, heat stabilizers and lubricants may be added to the ionomer resin of the present invention, and the adhesive resin composition may contain various additives. It is preferable to add various crosslinking inhibitors for the purpose of preventing crosslinking of the adhesive resin composition in the electron beam irradiation step in the manufacturing process of the heat-shrinkable tube.

[0019]

[Examples] Resin compositions shown in Tables 1 and 3 were prepared, and an ionomer resin tube (inner diameter 8 mm) was prepared using a melt extruder.
φ, wall thickness 1.0 mm) was produced. Further, resin compositions and adhesive compositions shown in Tables 2 and 4 were prepared, and an ionomer resin tube (inner diameter 8 mmφ, wall thickness 0.5 mm, having a structure having an adhesive layer on the inner surface) was prepared by using a melt coextruder. Thickness of adhesive layer
1.0 mm) was produced. For these tubes, the shrinkage of the inner diameter and the outer diameter that occurred over time was investigated.

These tubes are irradiated with an electron beam with an accelerating voltage of 1 MV for 100 KGy and then placed in a constant temperature bath set at 150 ° C., and compressed air is fed into the tubes so that the tube outer diameter becomes 20 mmφ. The diameter was expanded, the material was cooled and fixed to form a heat-shrinkable tube, and the shrinkage of the inner diameter and outer diameter that occurred over time was investigated. These heat-shrinkable tubes were colorless and excellent in transparency.

The shrinkage ratio of the inner diameter after extrusion of the tube is expressed by the following formula, which is represented by the ratio of the inner diameter of the tube which has been kept at 30 ° C. for 1 day and the inner diameter of which has been kept for 7 days at 30 ° C. Shrinkage (%) = 100 x {1- (inner diameter after 7 days / inner diameter after 1 day)} Similarly, for inner diameter shrinkage after expansion and expansion, the tube inner diameter after 1 day at 30 ° C after expansion and expansion And the ratio of inner diameter after 7 days at 30 ° C., and calculated by the above formula. Bloom of the plasticizer was visually evaluated.

[0022]

[Table 1]

[0023]

[Table 2]

[0024]

[Table 3]

[0025]

[Table 4]

The resins used in the table are as follows. Ionomer resin (1): Melt flow rate 0.7, melting point 88 ° C, metal ion = zinc ion Plasticizer (2): Dimethylphthalate Plasticizer (3): Neopentyl glycol dimethacrylate (* 1) Per 100 parts by weight of ionomer resin , Irganox 1010 (manufactured by Ciba Geigy, trade name) was commonly mixed in an amount of 1 part by weight. (* 2) Melt flow rate 50 (150 ℃, load 2160g) Ethylene ethyl acrylate-carbon monoxide copolymer 100
3 parts by weight of t-butylhydroxytoluene was added to 3 parts by weight. (* 3) Melt viscosity 30-60 poise (210 ℃), softening point 125
C. 3 parts by weight of t-butylhydroxytoluene was added to 100 parts by weight of the thermoplastic polyamide resin.

The heat shrinkable tubes of Examples 5 to 8 in Table 2 were
Cover the pipe made of polyvinyl chloride with an outer diameter of 10mmφ, 120 ℃
When it was heated for 3 minutes in the constant temperature bath, it was fitted to a polyvinyl chloride pipe well, heat-shrinked, and could not be peeled off by hand.

When the heat-shrinkable tube layer is made of an ionomer resin containing an appropriate amount of a plasticizer as in Examples 1 to 8 in Table 1, the inner diameter shrinkage after extrusion and expansion and diameter expansion is significantly reduced, and the dimensional accuracy is improved. An excellent heat-shrinkable tube was obtained. Example 3 is more preferable because the blooming of the plasticizer is reduced because the reactive plasticizer is used. Example 4 is a mixture of two types of plasticizers, but if the total amount is appropriate, mixing does not adversely affect the properties.

In Examples 5 to 8, a heat shrinkable tube having an adhesive layer on the inner surface can be obtained by using an ionomer resin in which the heat shrinkable tube layer is added with an appropriate amount of a plasticizer. As in Examples 5, 7, and 8, the adhesive layer using the adhesive resin composition mainly composed of the ethylene ethyl acrylate carbon monoxide copolymer has an advantage that there is no coloring.

On the other hand, with the ionomer resin containing no plasticizer as in Comparative Example 1, a tube having excellent dimensional accuracy cannot be obtained because it shrinks with time after extrusion and after expansion and expansion. Further, as in Comparative Example 2, when the amount of the plasticizer added is small, similarly to the case where the plasticizer is not added, it shrinks with time after extrusion and after expansion and expansion, and a tube having excellent dimensional accuracy cannot be obtained. Further, as shown in Comparative Examples 3 and 4, when the amount of the plasticizer added is too large, the shrinkage with time is particularly large after the expansion and expansion.

[0031]

As described above, according to the present invention, a crosslinked tube, a heat-shrinkable tube and a colorless and excellent adhesive layer which are colorless and have excellent transparency and whose inner diameter shrinkage does not change with time are provided. A heat-shrinkable tube having the above structure is obtained. Moreover, there is no problem of migration of the plasticizer, and the utility value of the crosslinked tube and the heat shrinkable tube is extremely large.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a heat-shrinkable tube having a structure having an adhesive layer on the inner surface.

[Explanation of symbols]

 1 heat shrinkable tube layer 2 adhesive layer

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location B32B 27/16 101 B32B 27/16 101 27/28 27/28 C08L 23/26 LDP C08L 23/26 LDP C09J 7/02 JHR C09J 7/02 JHR H01B 7/18 H01B 7/18 // B29K 23:00 105: 02 105: 24

Claims (4)

[Claims] 1. An ionomer resin having a structure in which intermolecular ethylene / acrylic acid or methacrylic acid copolymers are cross-linked with metal ions, and a plasticizer is ionomer resin.
A crosslinked tube comprising a resin composition containing 20 to 20% by weight. 2. A heat-shrinkable tube comprising the resin composition according to claim 1. 3. The heat-shrinkable tube according to claim 2, wherein an adhesive layer or a pressure-sensitive adhesive layer is formed on the inner surface. 4. The heat-shrinkable tube according to claim 3, wherein the adhesive layer is a resin composition mainly composed of an ethylene / ethyl acrylate / carbon monoxide copolymer.