WO2009125623A1 - Flame-retardant tube and heat-shrinkable tube made by using the same - Google Patents

Abstract

A non-halogen type flame-retardant tube which exhibits satisfactory flame retardance, tensile characteristics under high temperature, and heat deformation resistance; and a heat -shrinkable tube, more specifically, a flame-retardant tube produced by molding a flame-retardant resin composition which comprises 100 parts by mass of a base polymer comprising 5 to 80mass% of polyphenylene ether, 20 to 95mass% of a styrenic thermoplastic elastomer, and 0 to 70mass% of an olefinic polymer, 5 to 100 parts by mass of a phosphorus-containing flame retardant, 3 to 80 parts by mass of a nitrogenous organic compound, and 1 to 20 parts by mass of a polyfunctional monomer into a tube and irradiating the tube with an electron beam; and a heat-shrinkable tube produced by subjecting the tube to diameter expansion under heating and then setting the tube by cooling.

Description

Flame retardant tube and heat shrink tube using the same

The present invention relates to a tube and a heat-shrinkable tube made of a non-halogen flame retardant material and having excellent shape retention at high temperatures and tensile properties.

Various parts used in the fields of electronic equipment, OA equipment, consumer electronic equipment such as audio, video, DVD, vehicles, ships, etc., internal wiring, etc. are fire retardant tube for waterproof, dustproof, insulation, etc. In some cases, it is protected by close-packaging.

Such a flame-retardant tube used for close-packaging is required to have a flame resistance that can pass the UL standard vertical combustion test VW-1 so that it does not ignite even when the temperature of the parts rises. Conventionally, as a flame retardant material, a bromine-based or chlorine-based flame retardant is blended with a soft polyvinyl chloride composition or a vinyl polymer such as polyethylene, ethylene-ethyl acrylate copolymer, or ethylene-vinyl acetate copolymer. Although flame retardant resin compositions have been used, since such flame retardant materials have a problem of generating hydrogen halide gas during incineration, so-called halogen-free flame retardant containing no halogen compound. Alternatives to functional resin materials have been demanded.

On the other hand, tubes used for protecting cables and wirings of the above devices are required to have excellent flexibility and to be able to maintain tensile strength and elongation even at high temperatures. Further, there are cases where processing and deformation are performed in a state where an article to be packaged is inserted into the tube. Therefore, the tube used for these applications must satisfy not only the above-mentioned standards relating to flame retardancy but also the UL standards relating to tensile strength, elongation, and heat distortion resistance at high temperatures.

Non-halogen flame retardant resin material is a material in which metal hydroxide flame retardant such as aluminum hydroxide or magnesium hydroxide is blended with polyethylene, ethylene-ethyl acrylate copolymer, ethylene-vinyl acetate copolymer, etc. Has been put to practical use. However, if a metal hydroxide flame retardant is to pass the UL vertical combustion test VW-1, it must be added in a large amount, whereas if a metal hydroxide flame retardant is blended in a large amount, The mechanical properties are lowered, and it is impossible to achieve both flame retardancy and mechanical properties.

As a tube having both mechanical properties and flame retardancy using a metal hydroxide flame retardant, for example, JP-A-7-145288 (Patent Document 1) discloses an ethylene-vinyl acetate copolymer. There is disclosed a cross-linked tube composed of a flame retardant resin composition containing 150 to 230 parts by mass of a metal hydrate and 0.1 to 20 parts by mass of a foaming agent with respect to 100 parts by mass of the base polymer. .

The flame retardant tube contains a foaming agent, so that a tensile strength of 0.7 kg / mm ² or more and 100% or more can be secured even if a large amount of a metal hydroxide flame retardant is blended. However, Patent Document 1 does not evaluate tensile properties and strength at high temperatures, and such flame retardant materials may satisfy UL standards in terms of heat resistance, heat distortion resistance, and the like. Can not.

Phosphorus flame retardants such as phosphoric acid esters are also known, but the flame retardant effect is not sufficient, and there is a problem that satisfactory flame retardancy cannot be obtained unless a large amount is blended.

In order to reduce the content of the flame retardant, development of a non-halogen flame retardant material using a flame retardant polymer as a base polymer is in progress.
For example, flexible Noryl sold by SABIC Innovative Plastics Japan G.K. (formerly GE Plastics) uses a mixture of polyphenylene ether and styrene resin or styrene thermoplastic elastomer as the base polymer. Contains flame retardant. Based on the fact that polyphenylene ether is more flame retardant than polyolefin resin, it is possible to reduce the amount of flame retardant added, and to suppress the deterioration of tensile properties due to the large amount of flame retardant added. It is used as. However, it is not sufficient in terms of heat resistance, and especially if it is used as a heat shrinkable tube for close-packed packaging, the shape cannot be maintained during the diameter expansion process, or it melts in the heat shrinking process or the processing process of the package. Sometimes

Japanese Patent Application Laid-Open No. 2007-197615 (Patent Document 2) uses substantially no phosphorus flame retardant, uses a nitrogen flame retardant, and uses a polyphenylene ether resin and a thermoplastic elastomer as a base polymer. Furthermore, a non-halogen flame retardant resin composition containing a crosslinking aid has been proposed.

JP 7-145288 A JP 2007-197615 A

However, the non-halogen flame retardant resin composition disclosed in Patent Document 2 is intended for use as a coating material for electric wires and cables, and has not been evaluated as a tube. When applied to a tube, it is difficult to satisfy the UL standard with respect to shape retention after heating, shape retention after heating, tensile properties at high temperatures, and heat distortion resistance, and further improvements are required. .

The present invention has been made in view of such circumstances, and an object of the present invention is to provide a non-halogen flame retardant tube that can satisfy flame retardancy, tensile properties at high temperatures, and heat distortion resistance. There is to do.

The flame-retardant tube of the present invention comprises 5 to 80% by mass of polyphenylene ether, 20 to 95% by mass of styrene-based thermoplastic elastomer, and 0 to 70% by mass of olefin-based polymer. A flame-retardant resin composition containing ˜100 parts by mass, nitrogen-based organic compound 3 to 80 parts by mass, and polyfunctional monomer 1 to 20 parts by mass is formed into a tube shape and then irradiated with an electron beam.

The olefin polymer is preferably a copolymer of an olefin and an ethylenically unsaturated monomer, more preferably a block copolymer containing a polyolefin block and a polymer block of an ethylenically unsaturated monomer, or an olefin and an ethylenically unsaturated monomer. A copolymer with a monomer or a graft copolymer obtained by grafting a side chain of a polyolefin with a vinyl polymer or an ethylene-α-olefin copolymer.
Further, in the base polymer, when the content of the olefin polymer is 0% by mass, it is preferably 5 to 80% by mass of polyphenylene ether and 95 to 20% by mass of styrene thermoplastic elastomer.

The polyfunctional monomer is preferably a monomer having a carbon-carbon double bond, the phosphorus flame retardant is preferably an ester or ammonium salt of condensed phosphoric acid, and the nitrogen organic compound is An amino group and / or imide unit-containing compound is preferred.

The heat-shrinkable tube of the present invention is obtained by expanding the diameter of the above-mentioned tube of the present invention under heating and then cooling and fixing.

The flame retardant tube of the present invention has both tensile properties and flame retardancy, and further has excellent heat resistance and heat distortion resistance due to a crosslinking effect by electron beam irradiation. Since it has such excellent characteristics, the flame-retardant tube of the present invention is also applied to the heat-shrinkable tube of the present invention obtained by expanding the diameter of the flame-retardant tube of the present invention under heating and then fixing by cooling. As well as excellent tensile properties, flame retardancy, heat resistance, and heat distortion resistance.

Embodiments of the present invention will be described below. However, it should be considered that the embodiments disclosed herein are illustrative and non-restrictive in every respect. The scope of the present invention is defined by the terms of the claims, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

<Flame-retardant resin composition>
First, the resin composition used as the material for the flame-retardant tube of the present invention will be described.
The resin composition used as the flame retardant resin tube material of the present invention is a base polymer comprising 5 to 80% by mass of a polyphenylene ether resin, 20 to 95% by mass of a styrene thermoplastic elastomer, and 0 to 70% by mass of an olefin polymer. It contains 5 to 100 parts by mass of a phosphorus-based flame retardant, 3 to 80 parts by mass of a nitrogen-based organic compound, and 1 to 20 parts by mass of a polyfunctional monomer per 100 parts by mass.

(1) Base polymer The base polymer composition of the flame retardant resin composition is 5 to 80% by mass of a polyphenylene ether resin, 20 to 95% by mass of a styrene thermoplastic elastomer, and 0 to 70% by mass of an olefin polymer. When the olefin polymer is not included, the polyphenylene ether resin is preferably 5 to 80% by mass, and the styrene thermoplastic elastomer is preferably 95 to 20% by mass.

Polyphenylene ether is a resin obtained by oxidative polymerization of 2,6-xylenol synthesized using methanol and phenol as raw materials. Examples of the polyphenylene ether resin used in the present invention include not only polyphenylene ether but also modified polyphenylene ether modified with maleic anhydride or the like, or polymer alloy obtained by melt blending these with polystyrene resin, polyamide resin, polyester resin, and polypropylene resin. Can be mentioned. A polymer alloy of a polyphenylene ether resin and polystyrene is preferably used because it is excellent in compatibility with the styrenic thermoplastic elastomer and the extrusion processability is improved.

The styrenic thermoplastic elastomer used in the present invention is a block copolymer of a polystyrene block and a rubber component block. Diblock copolymers and triblock copolymers of rubber component blocks such as polybutadiene and polyisoprene with polystyrene blocks, hydrogenated polymers and partially hydrogenated polymers, maleic anhydride modified elastomers, epoxy modified elastomers, aromatics Vinyl-based thermoplastic elastomers can be used. Specifically, styrene-isobutylene-styrene copolymer, styrene-ethylene copolymer, styrene-ethylenepropylene copolymer, styrene-ethylenebutylene-styrene copolymer, styrene-ethylenepropylene-styrene copolymer, styrene -Isoprene copolymer, styrene-ethylene-isoprene copolymer, styrene-isoprene-styrene copolymer, styrene-butadiene copolymer and the like.

Such a styrenic thermoplastic elastomer is useful for improving the tensile elongation at break. The styrene content in the styrenic thermoplastic elastomer is preferably 10 to 70% by weight from the viewpoints of elongation and compatibility with polyphenylene ether.

The olefin polymer used in the present invention refers to a random copolymer, a block copolymer, or a graft copolymer of an olefin and an ethylenically unsaturated monomer, in addition to a polymer of one or more olefins.

Examples of the block copolymer include a copolymer having a polymer block composed of a polyolefin block and an ethylenically unsaturated monomer. The polyolefin block is not limited to a polymer block of one type of olefin monomer, but is a polymer block of two or more types of olefin monomers. There may be. The polyolefin block may be formed by polymerizing an olefin monomer, or may be formed by hydrogenation after polymerization of a monomer having a plurality of double bonds such as a diene monomer or a triene monomer.

The polymer block of the ethylenically unsaturated monomer is not limited to a polymer block composed of one type of ethylenically unsaturated monomer, and may be a polymer block of two or more types of copolymerizable monomers.

Examples of graft copolymers include polyolefins, random copolymers of olefins and ethylenically unsaturated monomers, and block copolymers as the main chain, and homopolymers, random copolymers, and block copolymers of ethylenically unsaturated monomers on the side chains. Can be mentioned.

As the olefin unit constituting the polyolefin block or polyolefin, ethylene, propylene, 1-butene, isobutene, pentene, hexene and the like can be used.
Examples of the ethylenically unsaturated monomer include unsaturated acids such as acrylic acid, methacrylic acid, methyl methacrylic acid, crotonic acid, (anhydrous) phthalic acid, (anhydrous) maleic acid and (anhydrous) itaconic acid, or carbon atoms of 1 to 8 Monoalkyl esters or esters of glycidyl alcohol; vinyl esters of fatty acids such as vinyl formate, vinyl acetate, vinyl propionate, vinyl valeate; aromatic vinyl compounds such as styrene, allylbenzene; acrylonitrile, acrylonitrile styrene, methacrylonitrile Vinyl cyanides such as can be used.

Accordingly, specific examples of the olefin polymer of the present invention include ultra low density polyethylene, low density polyethylene, medium density polyethylene, linear low density polyethylene, high density polyethylene, and the like, polypropylene, ethylene-α olefin copolymer. Olefin-based thermoplastic elastomer, ethylene-vinyl acetate copolymer, ethylene-ethyl acrylate copolymer, ethylene-methacrylic acid copolymer, ethylene-methyl methacrylate copolymer, ethylene-methyl acrylate copolymer, Styrene-ethylenebutylene-olefin crystal block copolymer, whose main chain is polyolefin (for example, polyethylene or polypropylene) or a copolymer of olefin and ethylenically unsaturated monomer (for example, ethylene-glycidyl methacrylate copolymer, Tylene-ethyl acrylate copolymer, ethylene-vinyl acetate copolymer, ethylene-ethylene acrylate-maleic anhydride copolymer) and vinyl polymer (for example, polystyrene, polymethyl methacrylate, or acrylonitrile) in the side chain Styrene copolymer, polyvinyl acetate, polymethyl acrylate, polyethyl acrylate, polybutyl acrylate, polyacrylic acid neutralized with metal ions, etc.) or ethylene-α olefin copolymer (eg, ethylene-vinyl acetate) Copolymer, ethylene-methyl acrylate copolymer, ethylene-methyl methacrylate copolymer, ethylene-ethyl acrylate copolymer, ethylene-butyl acrylate copolymer, ethylene-propylene rubber, ethylene acrylic rubber, ethylene -Glycidyl methacrylate Grafted polymer, ethylene-methyl acrylate-glycidyl methacrylate copolymer, ethylene-acrylic acid copolymer, ethylene-methacrylic acid copolymer, ethylene ionomer and polymers modified with maleic anhydride, etc.) Examples thereof include graft copolymers. Such an olefin-based polymer can also exhibit flame retardancy in the same manner as the styrene-based thermoplastic elastomer.

The content of each polymer (polyphenylene ether resin, styrene thermoplastic elastomer, olefin polymer) in the base polymer is 5 to 80% by mass of polyphenylene ether resin, 20 to 95% by mass of styrene thermoplastic elastomer, and The olefin polymer is 0 to 70% by mass. When the content of the olefin polymer is 0% by mass, it is preferable that polyphenylene ether resin: styrene thermoplastic elastomer = 5: 95 to 80:20.

If the content of the olefin-based polymer in the base polymer is more than 70% by mass, the content of the styrene-based thermoplastic elastomer having a relatively excellent flame retardancy must be relatively reduced, and the flame retardancy is reduced. It tends to decrease. Further, if the content ratio of the polyphenylene ether resin is too small and the content ratio of the styrene-based thermoplastic elastomer is too large, the flame retardancy tends not to be satisfied. On the other hand, if the content ratio of the polyphenylene ether resin becomes too large and the content ratio of the styrene thermoplastic elastomer and the olefin polymer becomes too small, the tensile properties tend not to be satisfied.

(2) Phosphorus flame retardant As the phosphorus flame retardant used in the present invention, orthophosphoric acid ester; a crosslinked structure having a branched PO ₄ group in a molecule such as pyrophosphoric acid, polyphosphoric acid, metaphosphoric acid, and ultraphosphoric acid, or Examples thereof include organic esters or ammonium salts of condensed phosphoric acid in which a phosphate is bonded linearly or cyclically; phosphonic acid esters; phosphinic acid esters. Of these, organic esters or ammonium salts of condensed phosphoric acid are preferably used, and may have an OH group in the molecule.

Specifically, trimethyl phosphate, triethyl phosphate, triphenyl phosphate, tricresidyl phosphate, trixylenyl phosphate, cresyl phenyl phosphate, cresyl 2,6-xylenyl phosphate, 2-ethylhexyl diphenyl phosphate, 1,3- Phenylene bis (diphenyl phosphate), 1,3-phenylene bis (di2,6-xylenyl phosphate), 1,2-phenylene bis (di-2,6-xylenyl phosphate), bisphenol A bis (diphenyl phosphate) ), Resorcinol bisdiphenyl phosphate, octyl diphenyl phosphate, diethylene ethyl ester phosphate, dihydroxypropylene butyl ester phosphate, ethylene disodium ester phosphate Fate, t-butylphenyl diphenyl phosphate, bis- (t-butylphenyl) phenyl phosphate, tris- (t-butylphenyl) phosphate, isopropylphenyl diphenyl phosphate, bis- (isopropylphenyl) diphenyl phosphate, tris- (isopropylphenyl) Phosphoric acid esters such as diphenyl phosphate, tris- (isopropylphenyl) phosphate, tris (2-ethylhexyl) phosphate, tris (butoxyethyl) phosphate, trisisobutyl phosphate; methylphosphonic acid, dimethyl methylphosphonate, diethyl methylphosphonate, ethylphosphonic acid, Propylphosphonic acid, butylphosphonic acid, 2-methyl-propylphosphonic acid, t-butylphosphonic acid, 2,3-di Phosphonic acid esters such as butylbutylphosphonic acid, octylphosphonic acid, and phenylphosphonic acid; Phosphinic acid esters such as diethylphosphinic acid, methylethylphosphinic acid, phenylphosphinic acid, diethylphenylphosphinic acid, and diphenylphosphinic acid; diisodedecylpenta Cyclic organophosphorus compounds such as erythritol diphosphite, 9,10-dihydro-9oxa-10-phospharenanthrene-10-oxide, Sanko Co., Ltd. HCA-HQ, SANKO-220, M-Ester, BCA, polyphosphorus Ammonium phosphate, melamine phosphate, melamine polyphosphate, melamine pyrophosphate, guanyl urea phosphate, guanidine phosphate, ADK STAB FP2100J or ADK STAB FP2200 commercially available from Adeka Corporation, Examples thereof include phosphorus and nitrogen compounds such as FLMESTAB NOR116FF manufactured by Ciba Specialty Chemicals. These phosphorus flame retardants can be used alone or in combination.
The phosphorus compound as described above may be one that is surfaced with melamine, melamine cyanurate, fatty acid, silane coupling agent or the like. When mixed with the base polymer, the surface treatment may be performed by an integral blend containing a surface treatment agent.

The phosphorus flame retardant is contained in an amount of 5 to 100 parts by mass per 100 parts by mass of the base polymer. If it is less than 5 parts by mass, it is difficult to ensure flame retardancy, and if it exceeds 100 parts by mass, the heat distortion resistance cannot be satisfied.

(3) Nitrogen-based organic compound As the nitrogen-based organic compound, derivatives or adducts such as cyanuric acid, melamine, and triazine are preferably used. Specifically, melamine resin, melamine cyanurate, isocyanuric acid, isocyanurate derivatives, An adduct or the like can be used. Of these, melamine and melamine cyanurate containing an amino group and / or an imide unit in the molecule are preferably used. The mechanism of such a nitrogen-based organic compound is not well understood, but when used in combination with a phosphorus-based flame retardant, the flame retardant is at a level that can pass the UL standard VW-1 test without causing a significant decrease in tensile properties. Can be secured.

Nitrogen-based organic compounds as described above are aminosilane coupling agents, vinyl silane coupling agents, epoxy silane coupling agents, silane coupling agents such as methacryloxy silane coupling agents; higher fatty acids such as stearic acid and oleic acid. It may be processed. The surface treatment may be carried out in advance, or the surface treatment may be carried out by blending the base polymer and other components, and blending the surface treatment agent during mixing.

The nitrogen-based organic compound is contained in an amount of 3 to 80 parts by mass per 100 parts by mass of the base polymer. If the amount is less than 3 parts by mass, the flame retardant effect due to the combined use with the phosphorus compound cannot be obtained, and if the amount is more than 80 parts by mass, the tensile elongation at break decreases and the initial tensile properties cannot be ensured.

(4) Polyfunctional monomer Examples of the polyfunctional monomer include monoacrylate, diacrylate, triacrylate, monomethacrylate, dimethacrylate, trimethacrylate, triallyl isocyanurate, triallyl cyanurate, etc. Monomers having a plurality of carbon-carbon double bonds in the molecule can be preferably used. From the viewpoint of crosslinkability, trimethacrylate monomers such as trimethylolpropane trimethacrylate are preferably used. Such a polyfunctional monomer can undergo a vinyl polymerization reaction with a diene moiety contained in the base polymer by electron beam irradiation, and can be expected to be useful for improving physical properties at high temperatures.

The polyfunctional monomer is contained in an amount of 1 to 20 parts by mass per 100 parts by mass of the base polymer. If the amount is less than 1 part by mass, the crosslinking effect cannot be obtained, the tensile properties at a high temperature are significantly lowered, and the thermal deformation at a high temperature is large. On the other hand, if it exceeds 20 parts by mass, unreacted monomers may remain, which may cause a reduction in flame retardancy.

(5) Other components Metal hydroxides such as aluminum hydroxide, magnesium hydroxide, calcium hydroxide, antimony trioxide, stannic acid as long as flame retardancy, heat distortion resistance, tensile properties, and volume resistivity are not impaired. Flame retardants such as zinc, zinc hydroxystannate, zinc borate and boron phosphate may be added.

The flame retardant resin composition used in the present invention further includes a polyolefin thermoplastic elastomer, a polyester thermoplastic elastomer, and a polyurethane thermoplastic elastomer for the purpose of improving various properties within a range that does not impair flame retardancy and mechanical strength. Other thermoplastic elastomers such as; impact-resistant polystyrene, styrene resin such as acrylonitrile-styrene resin, ABS resin; rubber such as EPDM, ethylene acrylic rubber, acrylic rubber, nitrile rubber; nylon, polybutylene terephthalate, polyethylene terephthalate, Various polymers such as polyethylene aphthalate and polyphenyl sulfide may be blended.

Further, various additives such as an antioxidant, a lubricant, a processing stabilizing aid, a colorant, a foaming agent, a reinforcing agent, a filler, a vulcanizing agent, a metal deactivator, and a silane coupling agent may be blended.

It can be prepared by blending the above components in predetermined amounts and mixing them using a known melt mixer such as a single screw extruder, a pressure kneader, or a Banbury mixer.

<Flame retardant tube>
The flame-retardant tube of the present invention is obtained by irradiating a tube-shaped molded product obtained by extruding a flame-retardant resin composition having the above composition into a tube shape with an electron beam.

It is considered that the base polymer is cross-linked through the multifunctional monomer by electron beam irradiation. And it is thought that the fall of the elastomeric property at the high temperature of a thermoplastic elastomer is suppressed by bridge | crosslinking, and, thereby, the tensile characteristic under a high temperature can be ensured now. Further, the partial network structure by cross-linking suppresses thermal deformation, and the shape can be maintained without being melted even by high-temperature treatment.

The size of the flame retardant tube is not particularly limited, but usually the wall thickness is preferably 1.0 mm or less, more preferably 0.8 mm or less.

In extrusion molding, it is preferable that a flame-retardant resin composition is once prepared, resin pellets having a predetermined composition are manufactured, and then the resin pellets are subjected to an extrusion molding machine.
The type of the extruder is not particularly limited, and any of a screw type and a non-screw type may be used, but a screw type is preferable. The type of screw is not particularly limited, but the ratio of the total length L to the cylinder bore diameter D (L / D) is usually preferably about 24 to 28.

Examples of electron beams used include accelerated electron beams, γ rays, X rays, α rays, and ultraviolet rays. Accelerated electron beams are most preferably used from the viewpoints of industrial use, such as ease of use of the radiation source, transmission thickness of ionizing radiation, and speed of crosslinking treatment.

The acceleration voltage of the accelerating electron beam may be appropriately set depending on the thickness of the tube layer and the composition of the resin composition that is the tube material. For example, in a tube having a thickness of 0.2 mm to 0.4 mm, the acceleration voltage is selected between 300 keV and 3 MeV. The irradiation dose is not particularly limited, but is usually 20 to 500 kGy.

<Heat shrinkable tube>
The heat-shrinkable tube of the present invention is obtained by cooling and fixing the flame-retardant tube of the present invention after expanding the diameter under heating.
In the diameter expansion treatment, the tube-shaped molded product is heated to a temperature equal to or higher than the softening point of the base polymer, and then expanded to a predetermined outer diameter by a method such as introducing compressed air into the tube, and then cooled. It can be obtained by fixing the shape. The expanded diameter is preferably about 2 to 4 times the original inner diameter.
The tube of the present invention is excellent in heat resistance, can be expanded without melting even at high temperatures, and can retain the expanded shape.

Since the heat-shrinkable tube of the present invention has excellent heat resistance, the heat-shrinkable tube can be shrunk to its original shape without melting again by a heat treatment at a softening point, specifically 100 to 250 ° C. Can do. Accordingly, the object to be packaged can be tightly packaged by heat treatment at 100 to 250 ° C. in a state where the object to be packaged such as electronic parts and cables to be protected and packaged is inserted into the tube.

The tube shrunk by the heat shrink treatment has the same tensile properties as the tube before the diameter expansion treatment, and can maintain the tensile properties required by the UL standard even under heating conditions. Therefore, the heat-shrinkable tube of the present invention can be used as a protective wrapping material for the purpose of moisture-proofing, waterproofing, dust-proofing, insulation, etc. of articles to be packaged such as electronic parts and cables.

The best mode for carrying out the present invention will be described with reference to examples. The examples are not intended to limit the scope of the invention.
In the following examples, “part” means “part by mass” unless otherwise specified.

[Measurement evaluation method]
First, the measurement evaluation method performed in the following examples will be described.
(1) Tensile properties The tube is subjected to a tensile test (tensile speed = 500 mm / min, distance between marked lines = 20 mm), and tensile strength (MPa) and tensile elongation at break (%) are measured with three samples each. Their average value was determined. A tensile strength of 10.4 MPa or more and a tensile elongation at break of 150% or more are acceptable levels.

(2) Heat resistance After leaving the tube in a gear oven set at 158 ° C. for 168 hours (7 days), the tensile test of (1) is performed. If the tensile strength after heat treatment is 7.3 MPa or more and the elongation is 100% or more, it is a pass level.

(3) Flame retardancy The VW-1 vertical flame retardancy test described in UL standard 224 was performed on five samples. In the test, when each sample was ignited 15 seconds for 5 times, the fire extinguished within 60 seconds, the absorbent cotton laid on the bottom was not burned by burning fallen objects, the kraft paper attached to the top of the sample burned, Those that did not burn were acceptable levels and were marked “OK”. If one of the 5 points did not reach the pass level, it was judged as “NG”.

(4) Heat deformation resistance It carried out according to JIS C3005. A metal rod having an inner diameter of 7.0 mm was inserted into the tube, placed in a thermostat set at 140 ° C., and preheated for 1 hour. After 1 hour, a jig having a diameter of 9.5 mm was pressed against the tube, and a load of 500 g was applied. The thickness of the tube layer after being allowed to stand for 1 hour in a state where a load was applied was measured, and the remaining ratio relative to the thickness before deformation was calculated. If the remaining rate is 50% or more, it is an acceptable level.
When evaluating a heat-shrinkable tube that has been subjected to diameter expansion and heat-shrinkage treatment, a metal rod having an inner diameter of 7.0 mm is inserted in advance during the heat-shrinkage treatment to form a metal rod insertion tube. The tube was preheated in a thermostatic bath, and the thickness after being allowed to stand for 1 hour under load was measured.

(5) Heat Shock Test After heating the tube for 4 hours in a gear oven set at 250 ° C., the tube was taken out and wrapped around a metal rod having the same diameter as the tube outer diameter, and the appearance of the tube was observed. If there was no particular change in appearance, it was an acceptable level and was set to “OK”.

[Preparation of flame retardant resin composition and preparation of tube]
Example Tube No. 1-15:
As shown in Table 1, polyphenylene ether resin 1 or 2, styrene thermoplastic elastomer 1 or 2, olefin polymer 1 to 4, phosphorus compound 1 to 3, nitrogen compound 1 or 2, polyfunctional monomer 1 Alternatively, 2 was blended in the amounts shown in Table 1. Furthermore, for 100 parts of the base polymer (total of polyphenylene ether resin, styrene thermoplastic elastomer and olefin polymer), 0.5 part of oleic acid amide, pentaerythritol-tetrakis [3- (3,5-di-t -Butyl-4-hydroxyphenyl) propionate] 3 parts and kneaded in a twin-screw mixer set at a die temperature of 280 ° C. 1 to 15 resin pellets were obtained.

Prepared resin composition No. 1 to 15 pellets were used in a melt extruder (45 mmφ, L / D = 24, compression ratio 2.5, full flight type) at an extrusion temperature of 260 ° C., an inner diameter of 7.0 mm, and a wall thickness of 0.3 mm. The tube-shaped molded product was extruded. The obtained tube was irradiated with an electron beam of 250 kGy with an acceleration voltage of 2.0 MeV. For the tubes 7 to 15, the tube No. was subjected to diameter expansion-heat shrink treatment. 1 to 15 were produced. No. Nos. 7 to 15 correspond to heat-shrinkable tubes.

Here, the diameter expansion-heat shrinkage treatment is preheated by standing in a thermostat set at 160 ° C. for 3 minutes, then expanded to 14 mm inner diameter by sending compressed air into the tube, and immediately taken out from the thermostat. Fix the shape by cooling with water. The heat shrinkable tube obtained by the diameter expansion treatment is heated at 160 ° C. for 3 minutes to shrink to the original size (inner diameter 7 mm).
The prepared tube No. For 1 to 15, tensile properties, heat resistance, flame retardancy, heat distortion resistance, and heat shock tests were measured and evaluated based on the above evaluation methods. The results are shown in Table 1.

Comparative tube No. 16-26:
Except having changed the compounding composition of the resin composition as shown in Table 2, each resin composition No. 16 to 26 resin pellets were extruded in the same manner as in the above examples to obtain a tubular molded product having an inner diameter of 7.0 mm and a wall thickness of 0.3 mm. No. Nos. 16 to 21, 23, and 26 were irradiated with an electron beam with an acceleration voltage of 2.0 MeV by the amount shown in Table 2. The tubes 16 to 21, 23, and 26 were subjected to the same diameter expansion-heat shrinkage treatment as in the above example.
Tube No. produced as described above was obtained. With respect to 16 to 26, tensile properties, heat resistance, flame retardancy, heat deformability, and heat shock tests were measured and evaluated based on the above evaluation methods. The measurement results are shown in Table 2.

In addition, the compound in Table 1 and Table 2 is as follows.
* 1: Polyphenylene ether 1: PX-100L manufactured by Mitsubishi Engineering Plastics Co., Ltd.
* 2: Polyphenylene ether 2: Xylon X9102 manufactured by Asahi Kasei Chemicals Corporation
This is a completely compatible polymer alloy of polyphenylene ether resin and polystyrene resin. * 3: Styrenic elastomer 1: Tuftec H1041 manufactured by Asahi Kasei Chemicals Corporation
This is a styrene-ethylenebutene-styrene copolymer having a styrene content of 30% by mass.
* 4: Styrene elastomer 2: SOE-SS9000 manufactured by Asahi Kasei Chemicals Corporation
This is a hydrogenated SBR.
* 5: Phosphorous compound 1: MELAPUR200 manufactured by Ciba
This is melamine polyphosphate having an average particle size of 4 μm, a phosphorus content of 13% by mass and a nitrogen content of 43% by mass.
* 6: Phosphorus compound 2: PX-200 from Daihachi Chemical Industry Co., Ltd.
This is a condensed phosphate ester with a phosphorus content of 9.0% by weight.
* 7: Phosphorus compound 3: BCA manufactured by Sanko Co., Ltd.
This is a cyclic organophosphorus compound.
* 8: Nitrogen-based compound 1: STABIACE MC-5S manufactured by Sakai Chemical Industry Co., Ltd.
This is melamine cyanurate (average particle size 0.5 μm).
* 9: Nitrogen compound 2: Melamine manufactured by Mitsubishi Chemical Corporation * 10: Multifunctional monomer 1: NK ester TMPT manufactured by Shin-Nakamura Chemical Co., Ltd.
Trimethylolpropane trimethacrylate * 11: Multifunctional monomer 2: Nippon Chemical Co., Ltd. Tyco (triallyl isocyanurate)
* 12: Olefin-based polymer 1: Lexpearl A1150 made by Nippon Polyethylene. This is an ethylene-ethyl acrylate copolymer (ethyl acrylate content 15 mass%, MFR 0.8 (190 ° C., load 2.16 kg)).
* 13: Olefin polymer 2: Elvalloy 1125AC manufactured by DuPont. This is an ethylene-methyl acrylate copolymer (methyl acrylate content 27 mass%, MFR 0.6 (190 ° C., load 2.16 kg)).
* 14: Olefin polymer 3: Dynalon 4600P manufactured by JSR Corporation. This is a styrene-ethylenebutylene-olefin crystal block copolymer.
* 15: Olefin polymer 4: MODIPA-A1100 manufactured by NOF Corporation. This is a polymer whose main chain is low density polyethylene and grafted with polystyrene.

Reference tube No. 31, 32:
A flexible Noryl resin compound manufactured by SABIC Innovative Plastics LLC was extruded in the same manner as in the above example to obtain a tubular molded product. The obtained tube was irradiated with an electron beam in the same manner as in Example 1, and further subjected to diameter expansion-heat shrinkage treatment. 31 and 32 were produced. The prepared tube was measured and evaluated for tensile properties, heat resistance, flame retardancy, heat distortion resistance, and heat shock based on the above evaluation methods. The results are shown in Table 3.

No. 1 to 9 are 5 to 100 parts by weight of a phosphorus-based flame retardant and 3 to 3 parts by weight of a nitrogen-based organic compound per 100 parts by weight of a base polymer containing 5 to 80% by weight of polyphenylene ether and 95 to 20% by weight of a styrene thermoplastic elastomer. This is a tube crosslinked by electron beam irradiation using a flame retardant resin composition containing 80 parts by mass and 1 to 20 parts by mass of a polyfunctional monomer as a material, and has tensile properties, flame resistance, heat resistance, and heat distortion resistance. The heat shock test was acceptable. No. 10 to 15 are cases where a blend of 20 to 40% by mass of polyphenylene ether, 20 to 30% by mass of a styrene thermoplastic elastomer, and 40 to 50% by mass of an olefin polymer is used as a base polymer. The tensile properties, flame retardancy, heat resistance, heat distortion resistance, and heat shock test of the tube cross-linked by irradiation were acceptable levels. No. 7, 8, and 9 are No. 1, respectively. The tubes 1, 3, and 6 are the same resin composition as the material. Comparing the evaluation results of the corresponding tubes, it can be seen that the characteristics before the treatment are maintained, with the characteristics hardly deteriorated even by the diameter expansion-heat shrink treatment.

No. 24 is a tube which was not irradiated with an electron beam. Reference numeral 22 denotes a tube made of a resin composition that does not contain a polyfunctional monomer. In either case, the tube was melted in the heat resistance test and heat shock test, and the shape could not be maintained. Since these were not subjected to electron beam irradiation or contained no polyfunctional monomer, the crosslinking effect by electron beam irradiation was not obtained, and they could not withstand high-temperature heat treatment. Therefore, it cannot be used as a heat shrinkable tube premised on high-temperature heat treatment.

The polyfunctional monomer content is too high (No. 23), the polyphenylene ether content in the base polymer is too low (No. 17), or the phosphorus flame retardant content is too low (No. 18). When there was too much polyolefin resin (No. 26), flame retardance could not be satisfied.
On the other hand, the content ratio of polyphenylene ether and styrene-based thermoplastic elastomer in the base polymer is appropriate, contains an appropriate amount of phosphorus-based flame retardant, polyfunctional monomer, and nitrogen compounds are not affected even when cross-linking treatment is performed by electron beam irradiation. When containing 3 parts by mass (No. 6), the flame retardancy could be satisfied, but when containing only 1 part by mass of the nitrogen compound (No. 21), the flame retardancy might be satisfied. could not. This shows that the combined use of a nitrogen compound and a phosphorus flame retardant is useful for ensuring flame retardancy.

By increasing the content of the phosphorus-based flame retardant (No. 19), or by increasing the content ratio of the polyphenylene ether in the base polymer (No. 16), flame retardancy can be achieved without containing a nitrogen compound. Although it can be satisfied, the amount of deformation due to heat treatment increases due to an increase in the content of the phosphorus compound (No. 19), and due to an increase in the content ratio of polyphenylene ether (No. 16), the elongation is increased due to heating at high temperature It was too low to secure the heat resistance and the pass level of the heat shock test.

No. 25, the content ratio of the polyphenylene ether and the styrene-based thermoplastic elastomer in the base polymer is within the scope of the present invention, and a nitrogen compound and a polyfunctional monomer are blended in appropriate amounts to obtain a crosslinking effect. However, although the heat shock test passed, it was inferior in elongation at high temperature and heat distortion resistance. On the other hand, no. No. 21 is obtained by reducing the amount of the nitrogen compound and increasing the content of the phosphorus compound to obtain a crosslinking effect. Although it is a level which cannot satisfy flame retardance in any case, it turns out that a phosphorus compound of 100 parts or less is useful for ensuring elongation under high temperature and heat deformation resistance.

Furthermore, No. 4 and no. 19 shows that when a base polymer that does not contain an olefin-based polymer is used, the content ratio of polyphenylene ether and styrene-based elastomer in the base polymer is required to maintain flame retardancy, heat resistance, and strength at high temperatures. It can be seen that it is effective to control the total amount of flame retardant by using (polyphenylene ether: styrene-based elastomer) in the range of 5:95 to 80:20 and using a nitrogen compound and a phosphorus compound in combination. .

No. 20 and no. From comparison with 5, the elongation tends to decrease as the content of the nitrogen-based compound increases. When the content of the nitrogen-based compound is 90 parts by mass, the initial tensile characteristics cannot be secured. From the point of tensile properties, it is understood that it is necessary to consider the content balance between the phosphorus compound and the nitrogen compound.

In addition, from Table 3, when soft noryl is used, the flame retardancy in the tube cannot be satisfied, and the crosslinking effect cannot be obtained even by electron beam irradiation. It was difficult to maintain the shape, and the deformation after high temperature treatment was large.

The tube of the present invention and the heat shrinkable tube are non-halogen type tubes that can satisfy the flame resistance of the UL standard VW-1 test, and also satisfy the UL standard tensile properties, strength, and heat deformation even at high temperatures. It can be used for electronic equipment, OA equipment, consumer electronic equipment such as audio, video, DVD, Blu-ray, tubes used for protecting internal wiring and parts of vehicles, ships, etc. It can be used as a heat shrinkable tube.

Claims (9)

1. 5-100 parts by mass of a phosphorus-based flame retardant per 100 parts by mass of a base polymer of 5-80% by mass of polyphenylene ether, 20-95% by mass of a styrene thermoplastic elastomer, and 0-70% by mass of an olefin polymer, a nitrogen-based organic compound A flame-retardant tube obtained by forming a flame-retardant resin composition containing 3 to 80 parts by mass and 1 to 20 parts by mass of a polyfunctional monomer into a tube shape and then irradiating it with an electron beam.
2. The flame retardant tube according to claim 1, wherein the base polymer is 5 to 80% by mass of polyphenylene ether and 95 to 20% by mass of a styrene thermoplastic elastomer.
3. The flame retardant tube according to claim 1, wherein the olefin polymer is a copolymer of an olefin and an ethylenically unsaturated monomer.
4. The flame retardant tube according to claim 3, wherein the copolymer is a block copolymer including a polyolefin block and a polymer block of an ethylenically unsaturated monomer.
5. The olefin polymer is a copolymer of an olefin and an ethylenically unsaturated monomer or a graft copolymer obtained by grafting a side chain of a polyolefin with a vinyl polymer or an ethylene-α olefin copolymer. Flame retardant tube.
6. The flame retardant tube according to any one of claims 1 to 5, wherein the polyfunctional monomer is a monomer having a carbon-carbon double bond.
7. The flame retardant tube according to any one of claims 1 to 6, wherein the phosphorus flame retardant is an ester or ammonium salt of condensed phosphoric acid.
8. The flame retardant tube according to any one of claims 1 to 7, wherein the nitrogen-based organic compound is an amino group and / or imide unit-containing compound.
9. A heat-shrinkable tube obtained by expanding the diameter of the tube according to any one of claims 1 to 8 under heating and then fixing by cooling.