JP2008097918A - Non-halogen flame-resistant wire excelling in terminal workability - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a non-halogen flame-resistant wire excelling in terminal workability by improving mechanical strength. <P>SOLUTION: This non-halogen flame-resistant wire excelling in terminal workability is composed by forming a covering layer with a resin composition prepared by mixing 40-300 pts.wt. of metal hydroxide and 0.5-10 pts.wt. of wax formed of polypropylene, in 100 pts.wt. of a mixture of a polyolefin-based polymer comprising 20-40% of polyethylene, 20-40% of polypropylene and 10-30% of a propylene-butene copolymer resin. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a non-halogen flame retardant electric wire excellent in terminal processability.

  Conventionally, polyvinyl chloride (hereinafter referred to as PVC), which is inexpensive and highly flame retardant, has been widely used as an electric wire / cable coating material. However, since PVC contains a halogen element, it has been pointed out that dioxins are generated during incineration of waste electric wires, and non-halogenation has been strongly desired.

  Non-halogen flame retardant wires and cables include olefin polymers that do not contain halogen elements and flame retardants containing either or both of magnesium hydroxide and aluminum hydroxide, as well as melamine cyanurate, zinc borate, and metal borate salts. What is comprised from the flame-retardant adjuvant is known (patent documents 1, 2).

  As an olefin polymer that does not contain a halogen element by the above-mentioned technology, in addition to polyethylene (hereinafter referred to as PE), an ethylene / ethyl acrylate copolymer (hereinafter referred to as PE) that forms a carbonized film having an oxygen barrier effect that is advantageous for flame retardancy during combustion EEA) or ethylene / vinyl acetate copolymer (hereinafter referred to as EVA) alone or blends are mainly used. Furthermore, it is known that the flame retardant and the flame retardant aid are used in combination in order to enhance the flame retardancy.

  In the case of electric wires for equipment, the pressure contact connector shown in FIG. 1 is attached to the end of the electric wire made of these resin compositions.

  That is, the connector 10 includes a strain relief 12 that holds the electric wire 11 and a metal fitting 13 having a grooved blade that comes into contact with the core wire 11a of the electric wire 11, and the terminal of the electric wire 11 is driven and held between the strain reliefs 12. The coating layer 11b is broken by a groove blade formed on the metal fitting 14, and the core wire 11a and the metal fitting 13 are brought into electrical contact.

JP-A-5-194802 JP 2003-160698 A

However, a resin composition made of an olefin polymer is softer and more easily deformed than a conventional PVC electric wire. When the deformation occurs, the electric wire 11 is easily pulled out from the connector 10, and in the worst case, a conduction failure occurs, which is a problem to be improved. Further, there are cases where scratches occur when the edges are rubbed during wiring work or the core wire 11a is exposed.
Then, the objective of this invention is providing the non-halogen flame-retardant electric wire which solved the said subject, improved mechanical strength, and was excellent in terminal workability.

  In order to achieve the above object, the present invention of claim 1 is characterized in that 100 parts by weight of a polyolefin polymer composed of polyethylene, polypropylene, propylene / butene copolymer resin, 40 to 300 parts by weight of metal hydroxide, and polypropylene. A non-halogen flame-retardant electric wire excellent in terminal processability, characterized in that a coating layer is formed with a resin composition in which 0.5 to 10 parts by weight of a wax is mixed.

  The invention according to claim 2 is characterized in that the polyolefin polymer mixture comprises 20 to 40% by weight of polyethylene, 20 to 40% by weight of polypropylene, and 10 to 30% by weight of propylene / butene copolymer resin. It is a non-halogen flame retardant wire with excellent resistance.

  The invention according to claim 3 is the non-halogen flame-retardant electric wire excellent in terminal processability according to claim 1 or 2, wherein maleic anhydride copolymer is added in an amount of 10 to 30 parts by weight per 100 parts by weight of the polyolefin polymer mixture. .

  According to a fourth aspect of the present invention, the maleic anhydride copolymer is one of ethylene / vinyl acetate copolymer, ethylene / ethyl acrylate, ethylene butene copolymer, and ethylene / propylene rubber grafted with maleic anhydride. The non-halogen flame-retardant electric wire excellent in terminal processability according to claim 3, comprising the mixture of

  The invention according to claim 5 is the non-halogen flame-retardant electric wire excellent in terminal processability according to any one of claims 1 to 4, wherein the yield strength of the resin composition is 30 MPa or more.

  The invention of claim 6 is the non-halogen flame-retardant electric wire excellent in terminal processability according to any one of claims 1 to 5, wherein the resin composition is subjected to a crosslinking treatment with ionizing radiation.

  According to the present invention, it is possible to obtain a non-halogen flame retardant electric wire having excellent mechanical strength and good terminal processability.

  Hereinafter, a preferred embodiment of the present invention will be described in detail.

  In the present invention, 40 to 300 parts by weight of a flame retardant made of a metal hydroxide and 0.5 to 10 parts by weight of a wax made of polypropylene are added to 100 parts by weight of an olefin polymer made of polyethylene, polypropylene, and propylene / ethylene copolymer resin. By mixing, a non-halogen flame-retardant electric wire having low viscosity and excellent flame retardancy is supplied.

  Furthermore, the mechanical properties can be improved by including 10 to 30 parts by weight of maleic anhydride copolymer in the olefin polymer.

  These resin compositions can sufficiently satisfy the function of the electric wire, but if the yield strength is 30 MPa or more, the deformation of the electric wire when the electric wire is attached to the connector can be eliminated.

  Further, although the dose is not particularly defined, the mechanical properties can be further improved by crosslinking treatment with ionizing radiation.

  Examples of the polyethylene used in the present invention include high, medium and low density polyethylene, linear low density polyethylene, ultra-low density polyethylene, ethylene hexene copolymer, and ethylene octene copolymer.

  Examples of polypropylene include homo, block, and random types. Since this polypropylene has a high melting point (150-170 ° C.) and high mechanical strength, deformation of the resin composition can be suppressed.

  The propylene / butene copolymer resin is a novel polymer obtained by copolymerizing butene with a propylene main chain, has the same strength as polypropylene, has a low melting point of 75 ° C., and is highly compatible with polypropylene.

  The ratio of these three kinds of polymers is not particularly limited, but is preferably in the range of 20 to 40% by weight of polyethylene, 20 to 40% by weight of polypropylene, and 10 to 30% by weight of propylene / butene copolymer resin.

  The wax made of polypropylene to be added to the blend polymer is a polypropylene wax obtained by homopolymerizing propylene, or a wax having a number average molecular weight of 1000 to 20000 formed by copolymerizing propylene and other monomers such as ethylene. It has a higher melting point than ordinary fatty acid wax and improves the processability and elongation of polypropylene.

  The amount of the wax made of polypropylene is specified to be 0.5 to 10 parts by weight. If the amount is less than 0.5 parts by weight, the processability is poor, and if it exceeds 10 parts by weight, the elongation and cold resistance of the resin composition are low. It is because it falls.

  The reason why the wax is limited to polypropylene is that so-called fatty acid waxes such as stearic acid amide and oleic acid amide reduce the yield strength, and further reduce the flame retardancy due to the occurrence of bleeding.

  Examples of maleic anhydride copolymers include ethylene / vinyl acetate copolymers (EVA), ethylene / ethyl acrylate copolymers (EEA), ethylene / butene copolymers, and polymers obtained by grafting maleic anhydride onto ethylene / propylene rubber. It is done.

  The reason why 10 to 30 parts by weight of the maleic anhydride copolymer is added is that adhesion with a metal hydroxide such as magnesium hydroxide or aluminum hydroxide can be improved and yield strength can be improved. This is because if it is less than 10 parts by weight, there is no effect, and if it exceeds 30 parts by weight, the elongation decreases.

  The amount of addition of the metal hydroxide is defined as 40 to 300 parts by weight. If the amount is less than 40 parts by weight, the flame retardancy is insufficient. This is because the properties and elongation decrease. As the metal hydroxide to be used, magnesium hydroxide or aluminum hydroxide may be used alone or in combination. The surface is preferably used after silane treatment.

  As a result of intensive studies, we have found that there is a correlation between the yield strength of the material and the deformation at the time of connector pressure welding. The reason why the yield strength of this resin composition is specified to be 30 MPa or more is that deformation at the time of press contact does not occur if it is 30 MPa or more.

  By performing a crosslinking treatment with ionizing radiation on the resin breakage, the bonding strength between the polymers is increased, and the mechanical strength such as the yield strength can be further improved.

  In addition, a flame retardant aid, a colorant, carbon black, a crosslinking aid, a filler, a lubricant, and the like may be appropriately added to the above formulation.

  Table 1 below shows Examples 1 to 12, and Table 2 shows Comparative Examples 1 to 11.

  Samples used in Examples and Comparative Examples are shown below.

Propylene / Butene Copolymer Resin Polyethylene A (Density: 0.90 g / cm ³ MI: 0.8 g / 10 min)
Polyethylene B (density: 0.93 g / cm ³ , MI: 1.0 g / 10 min)
Polypropylene (melting point: 157 ° C, MI: 2g / 10min)
EVA (vinyl acetate amount: 42%, MI: 0.2 g / 10 min)
EEA (ethyl acrylate amount: 15%, MI: 0.8 g / 10 min)
Magnesium hydroxide (average particle size 1.0μm, silane coupling agent treatment)
Aluminum hydroxide (average particle size 0.8μm, silane coupling agent treatment)
Maleic anhydride copolymer (maleic anhydride copolymerized EEA, maleic anhydride modified amount: 2%)
Flame retardant aid (melamine cyanurate)
Antioxidant (Tetrakis- (methylene-3- (3 ′, 5′-di-tert-butyl-4′-hydroxyphenyl) propionate) methane)
The above samples were blended in the blending amounts shown in Tables 1 and 2, and the blended composition was kneaded with a pressure kneader set at 150 ° C. to prepare a compound.

  Using a 40 mm extruder maintained at 240 ° C., this compound was extrusion coated to an outer diameter of 0.88 mm on a core wire consisting of seven stranded wires having an outer diameter of 0.48 mm. Furthermore, a 1 Mrad electron beam was irradiated with the electron beam bridge | crosslinking equipment, and the crosslinked process electric wire sample was produced.

  The characteristics in Tables 1 and 2 were measured by the following method.

  Measurements of tensile strength, elongation, and yield strength were in accordance with JIS C-3005. That is, it pulled at a speed of 500 mm / min using a tube in which the core wire was removed from the electric wire. The target was tensile strength of 10 MPa or more and elongation of 150% or more.

  The moldability was measured by measuring the viscosity at 240 ° C. using a Capillograph (manufactured by Toyo Seiki), and the excellence in extrudability was expressed as 5000 Pa · s or less as pass (◯), and the more as failure (×).

  The terminal processability was implemented using an automatic pressure welding machine (DN · J: manufactured by AMP) and a connector with 15 poles (MiniCT).

  The deformation was determined based on FIG. That is, if the electric wire 11 is driven between the strain reliefs 12 and 12 and there is a deformation 14 which protrudes the auxiliary line 1 of the strain relief (connector hook) 12 in one of the 15 poles of the covering layer 11b, ×, all the strain reliefs Those within 12 auxiliary lines l were marked with ◯, and among those marked with ○, those with particularly small deformation were marked with ◎.

  Cold resistance was observed by observing the condition of the surface of the coating layer when the wire was held in a low temperature bath at −20 ° C. for 4 hours and then wrapped around a metal rod having the same diameter (φ0.88) as the wire. When observed with a magnifying glass, the case with cracks and pinholes was marked with ×, and the case without cracks was marked with ○.

  For flame retardancy, a vertical combustion test (VW-1) based on UL subject 785 was conducted, and flame extinguishing within 60 seconds was regarded as acceptable.

  As can be seen from Table 1, Examples 1 to 12 according to the present invention have good tensile strength, elongation, end workability, and flame retardancy.

  On the other hand, as in Comparative Examples 1 and 2, two types of polymer blends such as polyethylene A, polypropylene, ethylene / butene copolymer resin, and propylene are stretched and cannot satisfy end processability and cold resistance.

  Moreover, the polymer which does not mix | blend polypropylene like the comparative examples 3 and 4 cannot satisfy terminal processability.

  All flame retardants added with 40 to 300 parts by weight satisfy flame retardancy, but Comparative Example 5 less than 40 parts by weight does not satisfy flame retardancy, and Comparative Example 6 exceeds 300 parts by weight flame retardancy. I am satisfied with the properties but not the elongation.

  Tensile parts of maleic anhydride copolymer was added to 100 parts by weight of blend polymer, and the tensile strength was improved. On the other hand, if it is less than 10 parts by weight shown in Example 2, the tensile strength is not effective, and if it is 40 parts by weight exceeding 30 parts by weight shown in Comparative Examples 7 and 8, the tensile strength is improved but the elongation is not satisfied. .

  In the case of adding polypropylene wax in an amount of 0.5 to 10 parts by weight, the processability is satisfied, but in Comparative Example 5 in which the addition amount of polypropylene wax is 0, the processability is not satisfied and 15 parts by weight exceeding 10 parts by weight was added. Comparative Example 8 does not satisfy cold resistance.

  Further, in Comparative Examples 9 to 11 using fatty acid amide as the wax, the terminal processability was not satisfied due to the decrease in yield strength, and the flame retardancy was also decreased at the addition amount of 5 parts by weight.

  The terminal processability is satisfactory in the present invention, but the terminal processability is poor at 30 MPa or less as in Comparative Examples 1 to 4 and Comparative Examples 9 to 11, whereby the terminal processability has a yield strength of 30 MPa or more. It was discovered that it would not be deformed.

  Examples 9 and 10 subjected to ionizing radiation cross-linking have better tensile strength than Examples 1 and 6 which were not performed.

It is a fragmentary perspective view which shows the structure of a press-contact connector. It is explanatory drawing for determining the deformation | transformation of an insulating layer when an electric wire is driven into a pressure welding connector.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Pressure welding connector 11 Electric wire l1a Core wire 11b Insulating layer 12 Strain relief 13 Metal fittings

Claims (6)

  Resin composition obtained by mixing 40 to 300 parts by weight of a metal hydroxide and 0.5 to 10 parts by weight of a wax made of polypropylene into 100 parts by weight of a polyolefin polymer mixture made of polyethylene, polypropylene and propylene / butene copolymer resin. A non-halogen flame retardant electric wire excellent in terminal processability, characterized by having a coating layer formed of   2. The non-halogen flame retardant electric wire excellent in terminal processability according to claim 1, wherein the polyolefin polymer mixture comprises 20 to 40% by weight of polyethylene, 20 to 40% by weight of polypropylene, and 10 to 30% by weight of propylene / butene copolymer resin. .   The non-halogen flame-retardant electric wire excellent in terminal processability according to claim 1 or 2, wherein 10 to 30 parts by weight of maleic anhydride copolymer is added to 100 parts by weight of the polyolefin polymer mixture.   4. The maleic anhydride copolymer comprises one or a mixture of ethylene / vinyl acetate copolymer, ethylene / ethyl acrylate, ethylene butene copolymer, ethylene / propylene rubber grafted with maleic anhydride. Non-halogen flame retardant wire with excellent terminal processability.   The non-halogen flame-retardant electric wire excellent in terminal processability according to any one of claims 1 to 4, wherein the yield strength of the resin composition is 30 MPa or more.   The non-halogen flame-retardant electric wire excellent in terminal processability according to any one of claims 1 to 5, wherein the resin composition is crosslinked by ionizing radiation.

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