JPH0992055A - Method for producing flame-retardant foamed crosslinked polyolefin insulated wire - Google Patents

Abstract

(57) [Abstract] [PROBLEMS] To provide a method for producing a flame-retardant foamed crosslinked polyolefin insulated wire, which has excellent extrusion processability, high hardness, and excellent foaming stability. SOLUTION: The high density polyethylene (HDPE) having a density of 0.960 or more has a density of 0.91 and 75 to 95% by weight.
Ultra low density polyethylene (VLDPE) of 5 or less is 25 to
A silane grafter prepared by reacting 1 to 5 parts by weight of an organic unsaturated silane and 0.01 to 0.5 parts by weight of a free radical generator with respect to 100 parts by weight of a base polymer composed of 5% by weight. , A flame retardant masterbatch prepared by kneading a polyolefin, a halogen-based flame retardant, a flame retardant aid and a silanol condensation catalyst, and a pyrolytic foaming masterbatch and a silicone masterbatch are mixed and coated on a conductor by an extruder. A method for producing a flame-retardant foamed cross-linked polyolefin insulated wire, which comprises foaming and then contacting with water to cross-link.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a flame-retardant foamed crosslinked polyolefin insulated wire which has excellent extrusion processability, high hardness and excellent foaming stability.

[0002]

2. Description of the Related Art Generally, a flame-retardant foamed crosslinked polyolefin insulated wire is manufactured by crosslinking a flame-retardant foamed polyolefin prepared by kneading a flame-decomposable foaming agent into a flame-retardant polyolefin by electron beam irradiation or the like. . However, the crosslinking method by electron beam irradiation is not economical for manufacturing a small amount because the apparatus is very expensive and the running cost is high. As a simple method of crosslinking polyolefin,
A so-called silane cross-linking method in which the polyolefin is graft-reacted with an organic unsaturated silane in the presence of a free radical generator to carry out silane grafting, and then the silane grafter is brought into contact with water to cross-link in the presence of a silanol condensation catalyst is used. Is generally known. For example, it is disclosed in JP-B-48-1711, JP-A-57-49109 and the like. Conventionally, HDPE-based flame-retardant silane cross-linked polyolefin has a low flame-retardant acceptability for HDPE and tends to have a particularly low mechanical property. Further, when it comes to a foam type, HDPE-based is hard and foaming is stable. No, and there was a problem of extrusion processability in long run, and it was not put to practical use.

[0003]

SUMMARY OF THE INVENTION The present invention solves these problems and provides a method for producing a flame-retardant foamed crosslinked polyolefin insulated wire having excellent extrusion processability, high hardness and excellent foaming stability. It is intended for.

[0004]

DISCLOSURE OF THE INVENTION The present invention extrudes a composition containing a silane graftmer, a polyolefin, a halogen-based flame retardant, a flame retardant aid, a silanol condensation catalyst, a thermal decomposition type foaming agent and silicone as a main component. A method for producing a flame-retardant foamed crosslinked polyolefin insulated wire, which comprises foaming while covering on a conductor by a machine, and then contacting with water to crosslink, preferably a silane grafter,
Polyolefin, halogen-based flame retardant, flame retardant auxiliary agent and silanol condensation catalyst are mixed and prepared flame retardant master batch and pyrolysis foam master batch and silicone master batch are mixed, while covering the conductor with an extruder. A method for producing a flame-retardant foamed crosslinked polyolefin insulated wire, which comprises foaming and then contacting with water to crosslink, more preferably a high density polyethylene (HDPE) having a density of 0.960 or more is 75 to 95. Ultra-low density polyethylene (V
LDPE) 25 to 5 wt% base polymer 1
A silane grafter prepared by reacting 1 to 5 parts by weight of an organic unsaturated silane and 0.01 to 0.5 parts by weight of a free radical generator with respect to 00 parts by weight, a polyolefin, and a halogen-based flame retardant. , A flame retardant masterbatch prepared by kneading a flame retardant auxiliary agent and a silanol condensation catalyst, and a pyrolysis-type foaming masterbatch and a silicone masterbatch are mixed, and foamed while being coated on an electric conductor by an extruder, followed by water content. A method for producing a flame-retardant foamed crosslinked polyolefin insulated wire, which comprises contacting with and crosslinking.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below. The HDPE used in the silane graftmer of the present invention is added for the purpose of imparting hardness to the insulated electric wire so that the foamed insulated electric wire is not crushed. The density is 0.96 to obtain the desired hardness
0 or more is necessary, and the addition amount is 75 to 95% by weight, preferably 85 to 95% by weight of the base polymer. If it is less than 75% by weight, the desired hardness as an insulated wire cannot be obtained and the insulated wire is crushed so that the terminal processing cannot be performed. If it exceeds 95% by weight, mechanical properties are deteriorated, which is not practical. VLD used in the silane grafter of the present invention
PE is added for the purpose of maintaining the mechanical properties of the insulated wire. The density should be 0.915 or less in order to improve the acceptability with the flame retardant.
-5% by weight, preferably 15-5% by weight. If it exceeds 25% by weight, the HDPE will eventually fall below 75% by weight, the desired hardness cannot be obtained as described above, the insulated wire will not be crushed, and the terminal processing cannot be performed.
If it is below the range, the receptivity to the flame retardant is poor and the mechanical properties are deteriorated, which is not practical.

The organic unsaturated silane used in the silane grafter of the present invention is one which is grafted to the base resin so as to serve as a cross-linking point between the base resins. Examples of the organic unsaturated silane used in the present invention include those represented by the general formula RR′SiY ₂ (R is a monovalent olefin unsaturated hydrocarbon group, Y is a hydrolyzable organic group, and R ′ is an aliphatic unsaturated hydrocarbon. Other than monovalent hydrocarbon groups or compounds represented by the same as Y) are used. It is desirable to use an organic unsaturated silane in which R'is the same as Y and is represented by the general formula RSiY ₃ , such as vinyltrimethoxysilane, vinyltriethoxysilane, vinyltributoxysilane,
Examples thereof include allyltrimethoxysilane and allyltriethoxysilane. The addition amount of these is 1 to 5 parts by weight, preferably 1.
5 to 2.5 parts by weight. When the amount is less than 1 part by weight, sufficient grafting does not occur, and when the amount is more than 5 parts by weight, molding failure occurs and it is not economical. The free radical generator used in the silane graftmer of the present invention acts as an initiator of the silane grafting reaction. As the free radical generator used in the present invention, various organic peroxides having a strong polymerization initiation action are used. The addition amount of these is 0.01 to 0.5 with respect to 100 parts by weight of the base polymer.
Parts by weight, preferably 0.05 to 0.2 parts by weight.
If it is less than 0.01 part by weight, the silane grafting reaction does not proceed sufficiently, and if it exceeds 0.5 part by weight, the extrusion processability is deteriorated and the molding surface is deteriorated.

The polyolefin used in the flame retardant masterbatch of the present invention is not particularly limited as long as it has acceptability for the flame retardant, and a general ethylene-α-olefin copolymer, Examples of the α-olefin include C _{3 to} C ₁₂ such as propylene, butene-1, pentene-1, octene-1,4-methylpentene-1,4-.
Methylhexene-1,4,4-dimethylpentene-1,
Nonene-1, decene-1, undecene-1, dodecene
1 mag. Alternatively, ethylene-ethyl acrylate copolymer (EEA), ethylene-methyl methacrylate copolymer (EMMA), ethylene-vinyl acetate copolymer (EVA), chlorinated polyethylene (CPE) and mixtures thereof can be mentioned. . The halogen-based flame retardant used in the flame retardant masterbatch of the present invention,
Examples thereof include decabromodiphenyl ether, pentabromoethylbenzene, tetrabromophthalic anhydride, ethylenebistetrabromophthalimide, ethylenebispentabromodiphenyl, tetrabromobisphenol A and its derivatives, and perchlorocyclopentadecane.
Examples of the flame retardant aid used in the flame retardant masterbatch of the present invention include antimony trioxide, antimony pentoxide and the like. It is important to use the halogen-based flame retardant and the flame-retardant auxiliary together, and the mixing ratio of the halogen-based flame retardant: flame-retardant auxiliary is 1 to 5: 1 to 3, preferably 1 to 3: by weight ratio. When it is in the range of 1, a remarkable flame retardant effect is exhibited.

The halogen flame retardant and the flame retardant auxiliary are added in a total amount of 200 to 500 parts by weight based on 100 parts by weight of the polyolefin. 200
If it is less than 5 parts by weight, the desired flame retardancy cannot be obtained, and if it exceeds 500 parts by weight, there is a problem in productivity and it is not practical. The silanol condensation catalyst used in the flame retardant masterbatch of the present invention includes dibutyltin dilaurate, stannous acetate,
Dibutyltin diacetate, dibutyltin dioctoate,
Lead naphthenate, zinc caprylate, cobalt naphthenate,
Organometallic compounds such as tetrabutyl titanate, lead stearate, zinc stearate, cadmium stearate, barium stearate, calcium stearate and the like can be mentioned. The addition amount of these is 0.01 to 3 parts by weight, preferably 0.05 to 1 part by weight, based on 100 parts by weight of the above polyolefin. If the amount is less than 0.01 part by weight, a sufficient crosslinking reaction does not proceed, and if the amount is more than 3 parts by weight, crosslinking is locally promoted in the extruder at the time of extrusion and the appearance is considerably deteriorated. The silane graftmer and flame retardant masterbatch are mixed in a weight ratio of silane grafter: flame retardant masterbatch in the range of 35 to 65:65 to 35. Outside of this range, the desired flame retardancy and the degree of cross-linking cannot be achieved at the same time, or the extrudability is reduced, which is not practical.

The pyrolytic foaming masterbatch of the present invention is
Azodicarbonamide, N, N'-dinitrosopentamethylenetetramine, benzenesulfonyl hydrazide, toluenesulfonyl hydrazide, azobisisobutyronitrile, N, N'-dimethyl-N, which are usually used for foaming polyethylene as a foaming agent. A masterbatch in which a compound such as N, N'dinitroterephthalamide is kneaded in polyethylene is used. The addition amount of these is added according to the intended foaming rate as an insulated wire.

The silicone masterbatch of the present invention is added for the purpose of imparting lubricity during long run extrusion. As the silicone, a masterbatch in which dimethylpolysiloxane having a molecular weight of 100,000 to 1,000,000 is kneaded into polyethylene is preferable. If it is less than 100,000, the silicone will bleed during extrusion, impairing the appearance, and if it exceeds 1 million, the desired lubricity cannot be obtained. The addition amount of these is 1 to 5 parts by weight with respect to 100 parts by weight of the total compounding agent. When the amount is less than 1 part by weight, poor lubricity causes poor appearance during long-run extrusion, and when the amount is more than 5 parts by weight, mechanical properties are deteriorated and it is not economical. Further, as the silicone, a flame retardant masterbatch may be used alone or in the form of a masterbatch added and kneaded at the time of production.

As other additives, if desired, additives usually used, for example, antioxidants, neutralizing agents, ultraviolet absorbers, antistatic agents, pigments, dispersants, thickeners, metal deterioration preventing agents, Antifungal agents, flow regulators, other inorganic fillers, etc., or other synthetic resins may also be contained. The method for producing the flame-retardant foamed cross-linked polyolefin insulated wire of the present invention is as shown below, and first, to obtain predetermined physical properties in the flame-retardant silane-crosslinked polyolefin composed of the silane graftmer and the flame retardant masterbatch, A mixture of the wt% pyrolytic foaming masterbatch and the silicone masterbatch is charged into an extruder hopper. For the cylinder part, crosshead, and die part of the extruder, set the temperature controller at 160 to 180 ° C. Next, the conductor is set in a wire-sending device, and the conductor is heated at a predetermined temperature through a preheater to cover the nipple while being molded by a die and cooled in a cooling water tank. At this time, the linear velocity or temperature controller is set so that the desired capacitance and appearance can be obtained at the set coating diameter while passing the "capacitance measuring instrument" and "outer diameter measuring instrument" installed on the line. The temperature is finely adjusted and extrusion coating is performed.
The coated wire is inspected for external damage by a spark tester, stored in a predetermined container or the like, and then immersed in warm water for several hours to perform a crosslinking promoting treatment.

[0012]

EXAMPLES Examples will be described below. << Production of Silane Grafter >> First, the base polymer was kneaded and granulated using a pressure kneader in accordance with the blending ratio shown in Table 1. This mixture was mixed with an organic unsaturated silane and a free radical generator, kneaded with an extruder at an extrusion temperature of 200 to 250 ° C., strand cut and granulated to obtain a silane graftmer. << Production of Flame Retardant Masterbatch >> Polyolefin, a halogen-based flame retardant, a flame retardant aid and a silanol condensation catalyst were kneaded and granulated using a pressure kneader in accordance with the compounding ratios shown in Table 2. <Pyrolysis-type foam masterbatch> 1031T: High-density polyethylene (HDPE) with azodicarbonamide (AD
Polypan 1031T (DA)
Co., Ltd.] was used. << Production of Silicone Masterbatch >> 50% by weight of low-density polyethylene (LDPE) and 50% by weight of dimethylpolysiloxane of each molecular weight are kneaded using a pressure kneader, and strand cut to granulate the silicone masterbatch S1 to S4. did. S1: using dimethylpolysiloxane having an average molecular weight of about 400,000, S2: using dimethylpolysiloxane having an average molecular weight of about 600,000 S3: using dimethylpolysiloxane having an average molecular weight of about 20,000 S4: about average molecular weight Using 1.4 million dimethyl polysiloxane

* Raw materials used (1) HDPE: High density polyethylene (Density: 0.968g /
cm ³ , MI; 5.2g / 10min) (2) VLDPE: Ultra low density polyethylene (density: 0.90
5g / cm ³ , MI; 0.5g / 10min) (3) LDPE: low density polyethylene (density: 0.925g /
cm ³ , MI; 2.0 g / 10 min) (4) VTMOS: vinyltrimethoxysilane (5) DCP: dicumyl peroxide (6) EPR: ethylene-propylene binary copolymer (7) CPE: chlorinated polyethylene ( 8) B1: ethylenebispentabromodiphenyl (9) B2: decabromodiphenyl ether (10) Sb ₂ O ₃ : antimony trioxide (11) DBTDL: dibutyltin dilaurate (12) antioxidant: phenolic antioxidant / irganox 1010 (13) Lubricant: Low molecular weight polyethylene / sun wax 17
1P

* Evaluation method (14) External appearance of wire extrusion 50 mmφ extruder 120-150-170-180-
170 ° C L / D: 20, compression ratio: 3.5, conductor diameter: 0.45mm
φ, coating thickness: 0.25 mmt Evaluation: ◯>Δ> × in this order, and the level of ◯ was passed. (15) Foaming ratio (%) (1-d / d ₀ ) × 100 d ₀ : Density of material before foaming, d: Density of material after foaming (16) Capacitance Insulation covered by “capacitance monitor” The capacitance of the electric wire was measured and evaluated by comparison with a predetermined value. Evaluation: The order of ◯>△> ×, and the level of ◯ were passed. (17) Flame retardance According to UL-62 standard VW-1 vertical combustion test. (18) Terminal processability The insertability of the insulated insulated wire to the connector using PBT at the time of pressure welding was evaluated. Evaluation: The order of ◯>△> ×, and the level of ◯ were passed. (19) Tensile strength (MPa) and elongation (%) According to JIS K6760. (20) Gel fraction (%) 120 ° C, 20 hours, xylene immersion method

The resulting silane graftmer, flame retardant masterbatch, pyrolytic foaming masterbatch and silicone masterbatch were mixed in the ratios shown in Tables 3 to 5, and the foamed insulated electric wire was extruded using an extruder. Capacitance was measured with a measuring instrument installed on the line, and further cross-linked by immersion in warm water. Using this foam insulated wire, the foaming rate, gel fraction, tensile strength, elongation, flame retardancy and terminal processability were evaluated.

Table 1 Compounding agents G1 G2 G3 G4 G5 G6 G7 HDPE 90 60 100 85 80 95 VLDPE 10 40 15 20 5 LDPE 100 VTMOS 2 2 2 2 0.5 10 2 DCP 0.1 0.1 0.1 0.1 0.1 0.1 0.05

Table 2 Compounding agents N1 N2 N3 N4 N5 N6 N7 N8 EPR 65 60 50 55 65 45 70 40 CPE 35 40 50 45 35 55 30 60 B1 160 50 150 200 200 B2 175 150 200 75 150 Sb ₂ O ₃ 160 175 250 25 150 125 75 350 DBTDL 0.05 0.05 0.05 0.05 0.005 5 0.05 0.05 Antioxidant 5 5 5 5 5 5 5 5 Lubricant 5 5 5 5 5 5 5 5

Table 3 Example Comparative Example 1 2 3 4 4 1 2 3 4 4 << Compounding agent >> G1 45 50 40 60 G2 50 G3 50 G4 50 G5 50 N1 55 60 50 50 N2 50 40 50 50 1031T 5 5 5 5 5 5 5 5 5 S1 3 3 3 3 S2 3 3 3 3 << Evaluation items >> Wire extrusion appearance ○ ○ ○ ○ ○ ○ ○ ○ Foaming ratio (%) 35 35 35 40 40 30 40 40 Capacitance ○ ○ ○ ○ ○ ○ ○ ○ ○ Difficult Flammability ○ ○ ○ ○ ○ ○ ○ ○ Terminal processability ○ ○ ○ ○ × ○ × △ Tensile strength (MPa) 15 14 13 15 12 16 10 12 Elongation (%) 410 400 380 420 430 25 420 380 Gel fraction (%) 61 60 57 63 65 55 63 15 Overall evaluation ○ ○ ○ ○ × × × ×

Table 4 Comparative Example 5 6 7 8 9 10 11 << Compounding agent >> G1 50 50 50 50 50 G6 50 G7 50 N1 50 50 50 50 N2 50 50 50 1031T 5 5 5 5 5 5 5 S1 3 3 0.5 S2 3 10 S3 3 S4 3 << Evaluation items >> Wire extrusion appearance × ○ × × △ △ △ Foaming rate (%) ∧ 35 ∧ ∧ 25 25 20 Capacitance evaluation ○ Evaluation △ △ ○ Flame retardance value ○ Value ○ ○ ○ Terminal processing Poor △ Poor △ △ △ Tensile strength (MPa) Yes 11 Yes Yes Yes 7 9 6 Elongation (%) ∨ 450 ∨ ∨ 200 250 150 Gel fraction (%) 10 57 58 55 Overall evaluation × × × × × × ×

Table 5 Comparative Example 12 13 14 15 16 17 18 19 《Compounding agent》 G1 45 45 45 45 45 45 25 75 N1 75 N2 25 N3 55 N4 55 N5 55 N6 55 N7 55 N8 55 1031T 5 5 5 5 5 5 5 5 S1 3 3 3 3 3 S2 3 3 3 << Evaluation items >> Wire extrusion appearance △ ○ ○ × ○ × × ○ Foaming ratio (%) 20 30 40 ∧ 35 ∧ ∧ 35 Capacitance △ ○ ○ Evaluation ○ Evaluation ○ Flame retardation Property × × ○ Value × Value × Terminal processability × ○ × Impossible ○ Impossible ○ Tensile strength (MPa) 6 16 10 Yes 15 Yes Yes 16 Elongation (%) 200 420 420 ∨ 450 ∨ ∨ 400 Gel fraction ( %) 58 62 20 65 65 Overall evaluation × × × × × × × ×

As is clear from the table, Examples 1, 2,
The materials shown in Nos. 3 and 4 have high hardness, good end workability, excellent foaming stability, and excellent mechanical properties, flame retardancy, and extrudability. On the other hand, in all the comparative examples, the terminal processability, foaming stability, mechanical properties, flame retardancy, and extrusion processability are not balanced.

[0022]

According to the present invention, it is possible to obtain a flame-retardant foamed crosslinked polyolefin insulated wire which has excellent extrusion processability, high hardness and excellent foaming stability.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location C09D 151/06 PGX C09D 151/06 PGX H01B 3/30 H01B 3/30 Z 7/34 7/34 B // B29K 23:00

Claims (4)

[Claims] 1. A silane grafter, a polyolefin,
A halogen-based flame retardant, a flame retardant aid, a silanol condensation catalyst, a thermal decomposition type foaming agent and a composition containing silicone as a main component,
A method for producing a flame-retardant foamed crosslinked polyolefin insulated wire, which comprises covering a conductor with an extruder to foam and then contacting with water to crosslink. 2. A flame retardant masterbatch prepared by kneading a silane grafter, a polyolefin, a halogen-based flame retardant, a flame retardant aid and a silanol condensation catalyst, a pyrolytic foaming masterbatch and a silicone masterbatch are mixed. A method for producing a flame-retardant foamed cross-linked polyolefin insulated wire, which comprises covering a conductor with an extruder to foam, and then contacting with water to cross-link. 3. The silane grafter has a density of 0.96.
75 to 95 high density polyethylene (HDPE) of 0 or more
1 to 5 parts by weight of an organic unsaturated silane and a free radical generator to 100 parts by weight of a base polymer consisting of 25 to 5% by weight of ultra low density polyethylene (VLDPE) having a weight% and a density of 0.915 or less. The method for producing a flame-retardant foamed cross-linked polyolefin insulated wire according to claim 1 or 2, which comprises reacting with 0.01 to 0.5 part by weight. 4. The method for producing a flame-retardant foamed crosslinked polyolefin insulated wire according to claim 1, 2 or 3, wherein the silicone is dimethylpolysiloxane having a molecular weight of 100,000 to 1,000,000.